Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 05/20/13
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1133 AM MDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 418 AM MDT SAT MAY 18 2013
FIRE WEATHER CONDITIONS ARE THE MAIN CONCERN FOR TODAY. AN UPR TROF
WL BE OVR THE GREAT BASIN TODAY AND WL MOVE INTO WRN CO BY EVENING
AND THEN WL BE MOVING ACRS THE STATE OVERNIGHT. AHEAD OF THE UPR
TROF...W TO SW WINDS SFC WINDS WL INCREASE TODAY WITH MOST AREAS
BEING BREEZY TO WINDY. DEW POINT FORECAST IS A BIT DIFFICULT...BUT
WL LEAN TOWARD THE HRRR FORECAST WHICH IS DRIER THAN THE NAM12 AND
THE RAP13. HIGH TEMPS TODAY SHOULD BE A LITTLE COOLER THAN
YESTERDAY...BUT STILL ABOVE NORMAL OVER THE ERN AREAS AND AROUND
NORMAL FOR THE SAN LUIS VALLEY. THE RED FLAG WARNING FOR BACA AND
EASTERN LAS ANIMAS COUNTIES STILL LOOKS GOOD...BUT IT NOW LOOKS LIKE
MIN RH VALUES AND WINDS MAY MEET RED FLAG CRITERIA FOR A LONG
ENOUGH PERIOD OVER MUCH OF THE SAN LUIS VALLEY AND OVER SRN EL PASO
COUNTY WHERE THE FUELS ARE DRY...AND THUS WL ADD THESE AREAS TO THE
RED FLAG WARNING.
BY LATE MORNING THERE WL PROBABLY BE SOME ISOLD SHOWERS/TSTMS OVR
THE MTS...WITH BEST CHANCES BEING ALONG THE CONTDVD. PCPN CHANCES
SHOULD THEN INCREASE OVR THE MTS AND HIGH VALLEYS IN THE AFTERNOON.
THE DRY LINE IS EXPECTED TO PUSH EAST INTO KS WITH THE SERN PLAINS
REMAINING DRY. THE NAM12 HAS SOME PCPN DEVELOPING OVR THE FAR SERN
PLAINS THIS AFTERNOON...BUT BELIEVE THAT THE DEW POINTS IN THE NAM
ARE TOO HIGH. HOWEVER THERE IS A CHANCE THAT WE COULD SEE SOME TSTM
DEVELOPMENT OVR ERN PORTIONS OF KIOWA COUNTY WHERE THE HIGHEST DEW
POINTS WL LIKELY BE...SO WL KEEP SOME ISOLD POPS IN THAT AREA. SPC
HAS THE FAR ERN PORTIONS OF KIOWA COUNTY IN THE SLIGHT RISK AREA FOR
TODAY. CHANCES FOR SHOWERS/TSTMS CONTINUE OVR AND NR THE HIGH
COUNTRY THIS EVENING...WITH LITTLE CHANCE FOR PCPN OVR THE SERN
PLAINS. SFC WINDS THIS EVENING WL BE WESTERLY AND BREEZY MOST AREAS
AND THEN WL BECOME MORE NWRLY BY LATE NIGHT. MOST AREAS SHOULD BE
DRY BY LATE NIGHT...BUT THE CENTRAL MTS WL PROBABLY CONTINUE TO SEE
A FEW SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 418 AM MDT SAT MAY 18 2013
SUNDAY-MONDAY NIGHT...MODELS CONTINUE TO INDICATE A COOL AND
GENERALLY UNSETTLED WEATHER PATTERN ACROSS THE AREA WITH A BROAD
UPPER TROUGH IN PLACE ACROSS THE INTERMOUNTAIN WEST THROUGH THE HIGH
PLAINS...ALONG WITH SEVERAL EMBEDDED SHORT WAVES TRANSLATING ACROSS
THE ROCKIES THROUGH THE PERIOD. FIRST WAVE ACROSS SOUTH CENTRAL
COLORADO EARLY SUNDAY MORNING CONTINUES TO TRANSLATE OUT ACROSS THE
SOUTHEAST PLAINS AND INTO WESTERN KANSAS SUNDAY AFTERNOON KEEPS THE
CHANCE FOR ISOLATED TO SCATTERED SHOWERS ACROSS THE AREA SUNDAY
MORNING AND AFTERNOON. MODELS CONTINUE TO INDICATE MAINLY HIGH BASED
STORMS WITH CONTINUED INVERTED V PROFILES...SAVE THE FAR SE PLAINS
WHERE LOW LEVEL MOISTURE FILTERS BACK INTO THE AREA FROM WESTERN
KANSAS WITH NORTHERLY FLOW BEHIND A BACKDOOR COLD FRONT MOVING
ACROSS EASTERN COLORADO.
NEXT SHORT WAVE DIGGING INTO NORTHWESTERN COLORADO LATE SUNDAY NIGHT
CONTINUES TO SLOWLY LIFT OUT ACROSS THE STATE THROUGH MONDAY NIGHT.
THIS PERIOD STILL LOOKS TO BRING THE BEST CHANCES OF WETTING
RAINFALL ALONG WITH ANOTHER LATE SEASON SHOT OF HIGHER ELEVATION
SNOWFALL...AS H7 TEMPS PROGGED TO DROP TO BETWEEN 0C AND 4C. WITH
THAT SAID...MONDAY STILL LOOKS TO BE THE COOLEST DAY OF THE UPCOMING
WEEK WITH POTENTIAL FOR SUB FREEZING OVERNIGHT LOWS ACROSS THE HIGH
MT VALLEYS SUNDAY NIGHT AND MONDAY NIGHT.
TUESDAY-WEDNESDAY...SLOW WARMING TREND ON TAP WITH BRISK NORTHWEST
FLOW ALOFT ACROSS THE AREA TUESDAY MODERATING THROUGH WEDNESDAY AS
UPPER LEVEL RIDGING BUILDS INTO WESTERN COLORADO. MODELS CONTINUE TO
INDICATE SHOWERS ACROSS THE HIGHER TERRAIN...MOST NUMEROUS ACROSS
THE EASTERN MTS TUESDAY AFTERNOON WITH DEVELOPING LOW LEVEL UPSLOPE
FLOW. MORE ISOLATED HIGH BASED STORMS REMAIN POSSIBLE WEDNESDAY
AFTERNOON.
THURSDAY-FRIDAY...UPPER RIDGE AMPLIFIES INTO THE HIGH PLAINS AS A
BROAD UPPER TROUGH CARVES OUT ACROSS THE PAC NORTHWEST. WARMING
ALOFT WILL ALLOW TEMPS TO WARM BACK TO AT AND SLIGHTLY ABOVE
SEASONAL AVERAGES INTO THE UPCOMING WEEKEND. ISOLATED HIGH BASED
STORMS REMAIN POSSIBLE OVER THE HIGHER TERRAIN WITH INCREASING
SOUTHERLY FLOW LEADING TO THE POTENTIAL FOR LATE AFTERNOON AND
EARLY EVENING THUNDERSTORMS ACROSS THE EASTERN PLAINS...AS LOW
LEVEL MOISTURE STREAMS BACK INTO EASTERN COLORADO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1130 AM MDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED DURING THE NEXT 24H AT ALL 3 TAF
SITES...KPUB...KALS AND KCOS.
GUSTY WINDS FROM THE WEST-SOUTHWEST (15G25KT) WILL BE POSSIBLE
THROUGH MID AFTERNOON. WINDS WILL SHIFT TO MORE NORTHWESTERLY BY
LATER IN THE AFTERNOON.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ224-227-233-
237.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...HODANISH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
419 AM MDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 418 AM MDT SAT MAY 18 2013
FIRE WEATHER CONDITIONS ARE THE MAIN CONCERN FOR TODAY. AN UPR TROF
WL BE OVR THE GREAT BASIN TODAY AND WL MOVE INTO WRN CO BY EVENING
AND THEN WL BE MOVING ACRS THE STATE OVERNIGHT. AHEAD OF THE UPR
TROF...W TO SW WINDS SFC WINDS WL INCREASE TODAY WITH MOST AREAS
BEING BREEZY TO WINDY. DEW POINT FORECAST IS A BIT DIFFICULT...BUT
WL LEAN TOWARD THE HRRR FORECAST WHICH IS DRIER THAN THE NAM12 AND
THE RAP13. HIGH TEMPS TODAY SHOULD BE A LITTLE COOLER THAN
YESTERDAY...BUT STILL ABOVE NORMAL OVER THE ERN AREAS AND AROUND
NORMAL FOR THE SAN LUIS VALLEY. THE RED FLAG WARNING FOR BACA AND
EASTERN LAS ANIMAS COUNTIES STILL LOOKS GOOD...BUT IT NOW LOOKS LIKE
MIN RH VALUES AND WINDS MAY MEET RED FLAG CRITERIA FOR A LONG
ENOUGH PERIOD OVER MUCH OF THE SAN LUIS VALLEY AND OVER SRN EL PASO
COUNTY WHERE THE FUELS ARE DRY...AND THUS WL ADD THESE AREAS TO THE
RED FLAG WARNING.
BY LATE MORNING THERE WL PROBABLY BE SOME ISOLD SHOWERS/TSTMS OVR
THE MTS...WITH BEST CHANCES BEING ALONG THE CONTDVD. PCPN CHANCES
SHOULD THEN INCREASE OVR THE MTS AND HIGH VALLEYS IN THE AFTERNOON.
THE DRY LINE IS EXPECTED TO PUSH EAST INTO KS WITH THE SERN PLAINS
REMAINING DRY. THE NAM12 HAS SOME PCPN DEVELOPING OVR THE FAR SERN
PLAINS THIS AFTERNOON...BUT BELIEVE THAT THE DEW POINTS IN THE NAM
ARE TOO HIGH. HOWEVER THERE IS A CHANCE THAT WE COULD SEE SOME TSTM
DEVELOPMENT OVR ERN PORTIONS OF KIOWA COUNTY WHERE THE HIGHEST DEW
POINTS WL LIKELY BE...SO WL KEEP SOME ISOLD POPS IN THAT AREA. SPC
HAS THE FAR ERN PORTIONS OF KIOWA COUNTY IN THE SLIGHT RISK AREA FOR
TODAY. CHANCES FOR SHOWERS/TSTMS CONTINUE OVR AND NR THE HIGH
COUNTRY THIS EVENING...WITH LITTLE CHANCE FOR PCPN OVR THE SERN
PLAINS. SFC WINDS THIS EVENING WL BE WESTERLY AND BREEZY MOST AREAS
AND THEN WL BECOME MORE NWRLY BY LATE NIGHT. MOST AREAS SHOULD BE
DRY BY LATE NIGHT...BUT THE CENTRAL MTS WL PROBABLY CONTINUE TO SEE
A FEW SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 418 AM MDT SAT MAY 18 2013
SUNDAY-MONDAY NIGHT...MODELS CONTINUE TO INDICATE A COOL AND
GENERALLY UNSETTLED WEATHER PATTERN ACROSS THE AREA WITH A BROAD
UPPER TROUGH IN PLACE ACROSS THE INTERMOUNTAIN WEST THROUGH THE HIGH
PLAINS...ALONG WITH SEVERAL EMBEDDED SHORT WAVES TRANSLATING ACROSS
THE ROCKIES THROUGH THE PERIOD. FIRST WAVE ACROSS SOUTH CENTRAL
COLORADO EARLY SUNDAY MORNING CONTINUES TO TRANSLATE OUT ACROSS THE
SOUTHEAST PLAINS AND INTO WESTERN KANSAS SUNDAY AFTERNOON KEEPS THE
CHANCE FOR ISOLATED TO SCATTERED SHOWERS ACROSS THE AREA SUNDAY
MORNING AND AFTERNOON. MODELS CONTINUE TO INDICATE MAINLY HIGH BASED
STORMS WITH CONTINUED INVERTED V PROFILES...SAVE THE FAR SE PLAINS
WHERE LOW LEVEL MOISTURE FILTERS BACK INTO THE AREA FROM WESTERN
KANSAS WITH NORTHERLY FLOW BEHIND A BACKDOOR COLD FRONT MOVING
ACROSS EASTERN COLORADO.
NEXT SHORT WAVE DIGGING INTO NORTHWESTERN COLORADO LATE SUNDAY NIGHT
CONTINUES TO SLOWLY LIFT OUT ACROSS THE STATE THROUGH MONDAY NIGHT.
THIS PERIOD STILL LOOKS TO BRING THE BEST CHANCES OF WETTING
RAINFALL ALONG WITH ANOTHER LATE SEASON SHOT OF HIGHER ELEVATION
SNOWFALL...AS H7 TEMPS PROGGED TO DROP TO BETWEEN 0C AND 4C. WITH
THAT SAID...MONDAY STILL LOOKS TO BE THE COOLEST DAY OF THE UPCOMING
WEEK WITH POTENTIAL FOR SUB FREEZING OVERNIGHT LOWS ACROSS THE HIGH
MT VALLEYS SUNDAY NIGHT AND MONDAY NIGHT.
TUESDAY-WEDNESDAY...SLOW WARMING TREND ON TAP WITH BRISK NORTHWEST
FLOW ALOFT ACROSS THE AREA TUESDAY MODERATING THROUGH WEDNESDAY AS
UPPER LEVEL RIDGING BUILDS INTO WESTERN COLORADO. MODELS CONTINUE TO
INDICATE SHOWERS ACROSS THE HIGHER TERRAIN...MOST NUMEROUS ACROSS
THE EASTERN MTS TUESDAY AFTERNOON WITH DEVELOPING LOW LEVEL UPSLOPE
FLOW. MORE ISOLATED HIGH BASED STORMS REMAIN POSSIBLE WEDNESDAY
AFTERNOON.
THURSDAY-FRIDAY...UPPER RIDGE AMPLIFIES INTO THE HIGH PLAINS AS A
BROAD UPPER TROUGH CARVES OUT ACROSS THE PAC NORTHWEST. WARMING
ALOFT WILL ALLOW TEMPS TO WARM BACK TO AT AND SLIGHTLY ABOVE
SEASONAL AVERAGES INTO THE UPCOMING WEEKEND. ISOLATED HIGH BASED
STORMS REMAIN POSSIBLE OVER THE HIGHER TERRAIN WITH INCREASING
SOUTHERLY FLOW LEADING TO THE POTENTIAL FOR LATE AFTERNOON AND
EARLY EVENING THUNDERSTORMS ACROSS THE EASTERN PLAINS...AS LOW
LEVEL MOISTURE STREAMS BACK INTO EASTERN COLORADO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 418 AM MDT SAT MAY 18 2013
VFR CONDITIONS ARE EXPECTED TO NEXT 24 HOURS AT KCOS...KPUB AND
KALS TAF SITES. SOME GUSTY SOUTHWEST WINDS ARE EXPECTED THIS
AFTERNOON AT THE TAF SITES...THEN BECOMING WESTERLY BY EVENING.
THIS AFTERNOON THERE COULD BE SOME SHOWERS/TSTMS IN THE VCNTY OF
KALS AND POSSIBLY NR KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 8 PM MDT THIS EVENING FOR
COZ224-227-233-237.
&&
$$
SHORT TERM...28
LONG TERM...MW
AVIATION...28
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
653 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A FRONTAL BOUNDARY EXTENDED FROM THE NORTH CENTRAL STATES, ACROSS
THE OHIO RIVER VALLEY TO THE WATERS OFF NORTH CAROLINA EARLY THIS
MORNING. THE BOUNDARY IS EXPECTED TO WEAKEN AND DISSIPATE AS IT
MEANDERS OVER THE SAME GENERAL AREA THROUGH MONDAY. MEANWHILE,
HIGH PRESSURE SHOULD REMAIN TO OUR NORTHEAST AND EAST. ANOTHER
FRONTAL BOUNDARY FROM THE NORTH IS FORECAST TO DROP INTO OUR
REGION ON TUESDAY NIGHT AND WEDNESDAY. THE FRONT MAY BEGIN TO LIFT
BACK TO THE NORTH LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A 09Z SURFACE ANALYSIS PLACED HIGH PRESSURE ACROSS THE NORTHEAST
INTO SOUTHEASTERN CANADA. A STATIONARY FRONT WAS DRAPED FROM THE
NORTHERN PLAINS TO THE UPPER OHIO VALLEY, THEN DOWN ACROSS
VIRGINIA AND EASTERN NORTH CAROLINA. AN UPPER AIR ANALYSIS SHOWED
A TROUGH IN THE WEST AND A RIDGE FROM THE MIDWEST INTO THE GREAT
LAKES. A TROUGH WAS IN NORTHERN NEW ENGLAND. THERE WERE SEVERAL
AREAS OF FOCUSED 850 MB WAA FROM THE MIDWEST DOWN THROUGH THE
PLAINS.
SOME LIGHT RETURNS SHOWING UP ON RADAR FROM OUR CENTRAL ZONES ON
SOUTHWARD. THIS APPEARS TO BE IN RESPONSE TO THE GRADUAL LOW-LEVEL
WAA AND AN UPPER-LEVEL JET ZIPPING BY. THE LATEST HRRR HAS THIS IDEA,
ALTHOUGH ITS AREAL COVERAGE IS OVERDONE SO FAR. ANY SHOWER SHOULD
BE LIGHT AND BRIEF THIS MORNING, THEREFORE JUST ADDED SOME
SPRINKLES FOR AWHILE FARTHER NORTH BEFORE SWITCHING TO A SHOWER
MENTION. THE HOURLY GRIDS WERE TWEAKED BASED ON THE 10Z
OBSERVATIONS, WHICH INCLUDED AN UPWARD ADJUSTMENT FOR MANY LOCALES.
OTHERWISE, OUR SENSIBLE WEATHER IS ANTICIPATED TO BE IN A
TRANSITIONING STATE TODAY. THIS IS COURTESY OF A MID LEVEL LOW
THAT IS GENERALLY WEAKENING AS IT SLIDES EASTWARD FROM THE OHIO
VALLEY. GIVEN THE NORTHWESTERLY FLOW ALOFT HOWEVER, THIS FEATURE
IS ANTICIPATED TO BE GENERALLY DIRECTED TOWARD OUR SOUTH TODAY.
THIS FEATURE IS EMBEDDED IN A BUILDING MID LEVEL RIDGE FROM THE
LOWER MISSISSIPPI VALLEY AND INTO THE GREAT LAKES. THE MAIN
FORECAST CHALLENGE FOR TODAY /AND EVEN THROUGH TONIGHT/ IS THE
TIMING AND AREAL COVERAGE OF SHOWERS ARRIVING FROM THE SOUTHWEST.
HIGH PRESSURE OVER SOUTHEASTERN CANADA IS FORECAST TO BUILD SOUTH-
SOUTHEAST, AND THIS MAY HELP HOLD THE NORTHEASTWARD ADVANCEMENT OF
THE SHOWERS.
THE MID LEVEL LOW IS PRODUCING SOME LOW-LEVEL WAA ALONG WITH SOME
THETA-E ADVECTION. THIS IS THE MOST PRONOUNCED ACROSS THE DELMARVA
AND THEN EVENTUALLY ACROSS SOUTHERN NEW JERSEY. THIS WILL RESULT
IN ISENTROPIC LIFT, HOWEVER THIS IS GENERALLY ON THE WEAKER SIDE.
THE OVERALL LIFT FARTHER NORTH IS EVEN WEAKER, HOWEVER THERE IS A
THERMAL GRADIENT FORECAST TO BE IN PLACE ALONG WITH A THETA-E
GRADIENT. AT THE SURFACE, A SOUTHEASTERLY FLOW IS EXPECTED WHICH
WILL GRADUALLY HELP TO INCREASE THE LOW-LEVEL MOISTURE. ALL OF
THIS IS FORECAST TO BE ON THE WEAKER SIDE, THEREFORE MOSTLY AN
INCREASE IN CLOUDS IS ANTICIPATED THROUGH THE DAY WITH SOME
SHOWERS MAINLY ACROSS THE DELMARVA. SOME ONGOING CONVECTION ACROSS
VIRGINIA EARLY THIS MORNING APPEARS TO BE FOCUSED NEAR THE STALLED
FRONT AND WITHIN AN AREA OF DEEPER MOISTURE. THIS ACTIVITY APPEARS
TO STAY JUST SOUTH OF DELAWARE EARLY THIS MORNING. THE FORECAST
SOUNDINGS ALSO INDICATE THE MOISTENING IS GRADUAL, THEREFORE WE
ARE NOT ANTICIPATING LOW CLOUDS DEVELOPING DESPITE THE
SOUTHEASTERLY FLOW. THE AIR MASS ACROSS OUR CWA TODAY LOOKS STABLE
ENOUGH, THEREFORE WE CONTINUED TO NOT INCLUDE A THUNDER MENTION.
AS FOR HIGH TEMPERATURES, THE AMOUNT OF CLOUD COVER ALONG WITH A
SOUTHEASTERLY FLOW WILL HELP TO KEEP THEM COOLER THAN YESTERDAY
FOR MANY AREAS. THIS WILL ALSO RESULT IN COOL CONDITIONS CLOSER TO
THE COAST. WE USED AN EVEN BLEND OF THE GFS/NAM MOS WITH SOME
MAINLY MINOR ADJUSTMENTS. THE WARMEST TEMPERATURES ARE MAINLY
ACROSS THE NORTHERN ZONES WHERE MORE FILTERED SUNSHINE MAY HOLD
THE LONGEST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
THE WEAK MID LEVEL LOW WILL CONTINUE TO TRACK EASTWARD INTO THE
DELMARVA. MEANWHILE, THE CENTER OF HIGH PRESSURE IS FORECAST TO
SLIDE SOUTHWARD OFF THE NEW ENGLAND COAST. THIS WILL RESULT IN A
CONTINUATION OF A SOUTHEASTERLY FLOW AT THE SURFACE, WHICH VEERS
TO MORE SOUTHERLY AT 850 MB. AS THIS OCCURS, THE LOW-LEVEL WAA IS
MAINTAINED WITH EVEN SOME INCREASE IN THE WINDS ACROSS THE
SOUTHERN ZONES TOWARD MORNING. THIS ALONG WITH CONTINUED THETA-E
ADVECTION IS EXPECTED TO RESULT IN ENOUGH ISENTROPIC LIFT TO
PRODUCE AN EXPANDING AREA OF SHOWERS FROM NORTH TO SOUTH. THE
AREAL COVERAGE OF THE SHOWERS IS SOMEWHAT IN QUESTION THOUGH,
THEREFORE WE OPTED TO HOLD THE POPS UNDER LIKELY. IT MAY TAKE ALL
NIGHT FOR ANY SHOWERS TO REACH THE FAR NORTHERN ZONES AS SOME
DRIER AIR MAY HOLD ON WITH THE MAIN THETA-E ADVECTION AND WAA
FOCUSED FARTHER SOUTH. THEREFORE, WE SLOWED THE INCREASE IN THE
POPS SOME FROM SOUTH TO NORTH. THE AIR MASS ACROSS OUR CWA LOOKS
STABLE ENOUGH, THEREFORE WE CONTINUED TO NOT INCLUDE A THUNDER
MENTION.
THE COMBINATION OF LOW-LEVEL WAA AND MOISTURE ADVECTION WILL
RESULT IN A RATHER CLOUDY NIGHT. THE CLOUDS ARE EXPECTED TO LOWER
THROUGH THE NIGHT AS THE BOUNDARY LAYER MOISTENS UP. THE FORECAST
SOUNDINGS GENERALLY SHOW THIS PROCESS NOT BEING RUSHED, THEREFORE
WE DID NOT INCLUDE DRIZZLE. THIS IS ALSO SUPPORTED BY JUST ENOUGH
DRY AIR IN THE BOUNDARY LAYER REMAINING A BIT LONGER. AN ONSHORE
FLOW CAN BE TRICKY SOMETIMES, THEREFORE WE WILL SEE HOW QUICK THE
MOISTURE MOVES IN AND DEEPENS. THIS SHOULD ALSO LIMIT ANY FOG
OVERNIGHT, ESPECIALLY AS THE DEW POINTS ARE NOT FORECAST TO
RAPIDLY INCREASE.
AS FOR LOW TEMPERATURES, WE WENT WITH AN EVEN GFS/NAM MOS BLEND.
THE TEMPERATURES ONCE THEY FALL BACK DURING THE EVENING MAY TEND
TO HOLD NEARLY STEADY AS CLOUDS LOWER.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
THE MID LEVEL PATTERN IS EXPECTED TO FEATURE THE POLAR VORTEX
WELL TO OUR NORTHEAST WITH A TROUGH SETTLING OVER THE WESTERN HALF
OF THE COUNTRY ON SUNDAY. THERE SHOULD BE A RIDGE OVER THE EAST
WITH ITS AXIS EXTENDING FROM THE WATERS OFF THE SOUTHEAST COAST TO
THE GREAT LAKES. THE POLAR VORTEX WILL REMAIN THE DOMINANT FEATURE
OVER EASTERN CANADA DURING THE NEW WEEK. MEANWHILE, THE TROUGH TO
OUR WEST WILL PROGRESS EASTWARD, GRADUALLY SQUEEZING THE RIDGE AND
PUSHING IT OUT OVER THE ATLANTIC. AS THE TROUGH BEGINS TO MOVE
TOWARD THE EASTERN STATES LATE IN THE WEEK, IT SHOULD BEGIN TO
INTERACT WITH THE POLAR VORTEX. ALL IN ALL, WE ARE ANTICIPATING A
RATHER UNSETTLED PERIOD.
SURFACE HIGH PRESSURE TO OUR NORTHEAST AND EAST WILL RESULT IN A
PREVAILING SURFACE FLOW FROM THE EAST TO SOUTH QUADRANT FOR SUNDAY
AND SUNDAY NIGHT. THE MOIST FLOW OFF THE OCEAN WILL LIKELY RESULT
IN A PERIOD OF LOW CLOUDS ALONG WITH A CHANCE FOR RAIN SHOWERS.
THE SURFACE FLOW IS FORECAST TO VEER TO THE SOUTH AND SOUTHWEST
FOR MONDAY AND MONDAY NIGHT CAUSING THE CLOUDS TO LIFT AND
TEMPERATURES TO WARM, RESULTING IN THE DEVELOPMENT OF UNSTABLE
CONDITIONS, ESPECIALLY AWAY FROM THE OCEAN. A FAIR AMOUNT OF LOW
LEVEL MOISTURE WILL REMAIN IN OUR REGION. AS A RESULT, WE WILL
CONTINUE TO MENTION A CHANCE OF SHOWERS AND WE WILL ALSO INCLUDE A
CHANCE OF THUNDERSTORMS FOR THE AFTERNOON AND INTO THE NIGHTTIME
HOURS ROUGHLY ALONG THE INTERSTATE 95 CORRIDOR AND AT LOCATIONS TO
THE WEST.
THE SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON TUESDAY AND
TEMPERATURES ARE EXPECTED TO RISE INTO THE LOWER AND MIDDLE 80S IN
MUCH OF OUR FORECAST AREA. LINGERING LOW LEVEL MOISTURE WILL HELP
ENHANCE THE INSTABILITY AND WE ARE ANTICIPATING SCATTERED SHOWERS
AND THUNDERSTORMS, ESPECIALLY IN THE AFTERNOON AND EVENING.
A FRONTAL BOUNDARY IS FORECAST TO DROP INTO OUR REGION FROM THE
NORTH FOR TUESDAY NIGHT AND WEDNESDAY. THERE IS A FAIR AMOUNT OF
UNCERTAINTY AS TO WHETHER THE FRONT WILL REMAIN OVER OR NEAR OUR
REGION THROUGH THE BALANCE OF THE WEEK OR IF IT WILL TRY TO LIFT
BACK TO THE NORTH. REGARDLESS, UNSETTLED CONDITIONS WILL LIKELY
CONTINUE.
WHILE THERE WILL BE A CHANCE OF PRECIPITATION IN THE FORECAST FOR
EACH DAY FROM SUNDAY THROUGH FRIDAY, THE WEEK SHOULD NOT BE A
TOTAL WASHOUT. ACTUALLY, MOST OF THE TIME PRECIPITATION WILL NOT
BE FALLING. OVERALL, TEMPERATURES FOR THE WEEK SHOULD AVERAGE
ABOVE NORMAL FOR THIS TIME OF THE YEAR.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
TODAY...VFR WITH CEILINGS MAINLY 8,000 TO 10,000 FEET LOWERING
SOME THROUGH THE AFTERNOON. LIGHT AND VARIABLE WINDS, BECOMING
SOUTHEASTERLY NEAR 10 KNOTS. AN ISOLATED LIGHT SHOWER AROUND THIS
MORNING, THEN ADDITIONAL SHOWERS ARE ANTICIPATED TO BE MOSTLY
SOUTH OF KPHL.
TONIGHT...VFR CEILINGS TO START, THEN THESE SHOULD LOWER TO MVFR
BY ABOUT 04Z. THERE IS A CHANCE SOME IFR CEILINGS DEVELOP, HOWEVER
CONFIDENCE IS LOW THEREFORE HELD CEILINGS JUST ABOVE FOR NOW.
SCATTERED SHOWERS DEVELOPING FROM SOUTH TO NORTH, WITH THE
GREATEST CHANCE MAINLY FROM THE KPHL METRO ON SOUTHWARD. ANY
SHOWERS WILL LOWER THE LOCAL VISIBILITY AT TIMES. ANY FOG SHOULD
BE LIMITED AS THE MOISTURE GOES INTO A LOWERING CLOUD DECK.
EAST-SOUTHEAST WINDS 5-8 KNOTS.
OUTLOOK...
SUNDAY AND SUNDAY NIGHT...MAINLY MVFR CEILINGS WITH POSSIBLE IFR
CONDITIONS AT TIMES. A CHANCE OF SHOWERS.
MONDAY THROUGH WEDNESDAY...MAINLY VFR. HOWEVER, MVFR AND IFR
CONDITIONS ARE POSSIBLE ESPECIALLY DURING THE LATE NIGHT AND EARLY
MORNING HOURS EACH DAY. ALSO, THERE WILL BE A CHANCE OF SHOWERS
AND THUNDERSTORMS WHICH COULD LOWER CEILINGS AND REDUCE THE
VISIBILITY.
&&
.MARINE...
HIGH PRESSURE CENTERED TO OUR NORTH WILL SETTLE SOUTHWARD SOME
THROUGH TONIGHT. MEANWHILE, A FRONTAL BOUNDARY REMAINS STALLED TO
OUR SOUTH. AS A RESULT, AN EAST TO SOUTHEAST FLOW WILL BECOME
DOMINANT THROUGH TONIGHT. THE PRESSURE GRADIENT IS FORECAST TO
TIGHTEN UP SOME THIS AFTERNOON AND TONIGHT, HOWEVER THE OVERALL
WIND IS FORECAST TO NOT BE ROBUST BELOW AN INVERSION. WE ARE
ANTICIPATING SOME INCREASE AS WE GO THROUGH TONIGHT ESPECIALLY
ACROSS THE SOUTHERN WATERS AND UP DELAWARE BAY /GUSTS TO 20
KNOTS/, HOWEVER WE CONTINUE TO KEEP THE WINDS BELOW ADVISORY
CRITERIA. THE SEAS WILL GRADUALLY RESPOND TO THE WINDS, HOWEVER
PERHAPS A LITTLE SLOWER THAN WHAT WAVEWATCH GUIDANCE SUGGESTS.
THEREFORE, CONDITIONS ARE FORECAST TO REMAIN BELOW ADVISORY
CRITERIA THROUGH TONIGHT.
OUTLOOK...
HIGH PRESSURE TO OUR NORTHEAST AND EAST WILL CONTINUE TO
INFLUENCE THE COASTAL WATERS OF NEW JERSEY AND DELAWARE INTO
TUESDAY. A FRONTAL BOUNDARY FROM THE NORTH IS FORECAST TO DROP
INTO OUR REGION FOR TUESDAY NIGHT AND WEDNESDAY.
WIND SPEEDS ARE FORECAST TO REMAIN LESS THAN 25 KNOTS FROM SUNDAY
THROUGH WEDNESDAY. WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO
AROUND 5 FEET ON SUNDAY AND SUNDAY NIGHT AND THEY COULD REMAIN AT
THAT LEVEL THROUGH AT LEAST WEDNESDAY AS A PERSISTENT SOUTHERLY
FLOW DEVELOPS.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...IOVINO
NEAR TERM...GORSE
SHORT TERM...GORSE
LONG TERM...IOVINO
AVIATION...GORSE/IOVINO
MARINE...GORSE/IOVINO
AREA FORECAST DISCUSSION
NWS MIAMI FL
905 AM EDT SAT MAY 18 2013
.UPDATE...
MORNING SOUNDING DATA INDICATES A MOISTENING TREND OF THE LOCAL
AIR MASS. THIS IS CONFIRMED BY RADAR THIS MORNING SHOWING
SCATTERED SHOWERS ALONG THE EAST COAST AND ATLANTIC, WITH EARLIER
SHOWERS OVER THE GULF OF MEXICO AS WELL. THIS ALL POINTS TO A
GENERAL INCREASE IN SHOWERS AND THUNDERSTORMS THIS AFTERNOON,
ESPECIALLY INTERIOR AND LAKE OKEECHOBEE AREAS WHERE SOUTHEAST TO
SOUTH LOW-LEVEL FLOW WILL FOCUS CONVERGENCE. MINOR MID-LEVEL SHORTWAVE
MOVING ACROSS SOUTH FLORIDA FROM THE GULF THIS AFTERNOON WILL COOL
THE MID-LEVELS A BIT THIS AFTERNOON, ACTING TO ERODE MID-LEVEL
CAPPING AND HELPING IN THE DEVELOPMENT OF A FEW STRONG STORMS
ACROSS THE INTERIOR/LAKE AREAS. LIGHTNING, GUSTY WINDS AND SMALL
HAIL ARE THE PRIMARY IMPACTS.
SHOWERS/STORMS THIS AFTERNOON WILL LIKELY MOVE LITTLE OR DRIFT
EAST, WHICH SHOULD RESULT IN METRO/COASTAL AREAS ALONG BOTH COASTS
REMAINING MOSTLY DRY THIS AFTERNOON. IN ALL, NO CHANGES OF NOTE TO
THE PREVIOUS FORECAST PACKAGE.
MOLLEDA
&&
.PREV DISCUSSION... /ISSUED 740 AM EDT SAT MAY 18 2013/
AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS AND POSSIBLY A THUNDERSTORM OR
TWO WILL CONTINUE ACROSS THE COASTAL ATLANTIC WATERS THROUGH THE
MORNING HOURS. STILL EXPECT A FEW OF THESE SHOWERS TO PUSH INLAND
THROUGH THE LATE MORNING HOURS. THEREFORE...KEPT VCSH MENTION AT ALL
EAST COAST SITES. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
PREV DISCUSSION... /ISSUED 300 AM EDT SAT MAY 18 2013/
SHORT TERM (TODAY-MONDAY)...
ANOTHER WARM AND PLEASANT WEEKEND IS ANTICIPATED ACROSS SOUTH
FLORIDA WITH TEMPERATURES REMAINING AROUND TO SLIGHTLY ABOVE NORMAL
EACH DAY. THE LATEST NUMERICAL GUIDANCE REMAINS PERSISTENT AND IN
GOOD AGREEMENT DEPICTING AN UPPER RIDGE BUILDING EASTWARD OVER THE
MS VALLEY TRAILING A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW ALOFT. AS THIS SHORTWAVE ADVANCES E-SEWD OVER THE
STATE...UPPER HEIGHTS WILL SLIGHTLY FALL OVER THE STATE BY THE END
OF THE DAY. MODEL SOUNDINGS ACROSS THE NORTHERN AND INTERIOR
LOCATIONS OF THE LOCAL AREA REFLECT THIS AND INDICATE SOME MID-
LEVEL COOLING BY 00Z (H5 TEMPS AROUND -11C) WITH MID-LEVEL LAPSE
RATES STEEPENING (-6 TO -7 C/KM). THIS COMBINED WITH LIGHT
SOUTHEAST LOW-LEVEL FLOW...A SUFFICIENT AMOUNT OF LOW-LEVEL
MOISTURE AND DAYTIME HEATING WILL SUPPORT A FEW STORMS LATER TODAY
THROUGH THE LATE AFTERNOON/EARLY EVENING TIME FRAME. THE BEST
CHANCE FOR THIS ACTIVITY WILL BE ACROSS THE INTERIOR AND NORTHERN
LOCATIONS. THE FSU GRIDDED LIGHTNING PROBABILITY DATABASE AND THE
LATEST GRIDDED MOS THUNDERSTORM PROBABILITIES ARE GENERALLY
OUTPUTTING 20-40 PERCENT CHANCES OVER THESE INTERIOR LOCATIONS
THROUGH THIS TIME. THE MAIN LIMITING FACTORS FOR WIDESPREAD DEEP
MOIST CONVECTION WILL BE A PERSISTENT MID-LEVEL CAP BETWEEN 650 MB
AND 700 MB ALONG WITH PLENTY OF MID-LEVEL DRY AIR EN-TRAINING INTO
ANY DEVELOPING CELLS. ANY STORM THAT DOES DEVELOP COULD BECOME
STRONG WITH THE MAIN IMPACTS BEING SMALL HAIL AND DAMAGING
STRAIGHT-LINE WINDS (40-55 MPH). THE LATEST HI-RES MODEL
REFLECTIVITIES BETWEEN THE WRF AND NAM GENERALLY LINE UP WELL AND
DEPICT SOME ACTIVITY INITIATING INLAND AND TOWARD THE NORTH AROUND
LAKE OKEECHOBEE THROUGH THE LATE AFTERNOON AND EARLY EVENING
PERIODS. SIMILAR CONDITIONS WILL PERSIST WITH THE EASTERLY LOW-
LEVEL FAVORING INTERIOR AFTERNOON ACTIVITY AGAIN ON SUNDAY AND
MONDAY. OVERNIGHT AND THROUGH THE EARLY MORNING HOURS EACH
DAY...SHOWERS AND A FEW STORMS ACROSS THE ATLANTIC WATERS AND THE
EAST COAST LOCATIONS WILL REMAIN POSSIBLE DUE TO THE CONFLUENT
BOUNDARIES SETTING UP DOWNSTREAM OF THE BAHAMAS AND RADIATIONAL
CLOUD-TOP COOLING.
LONG TERM (MONDAY NIGHT-FRIDAY)...
THE GFS/ENSEMBLE MEAN AND ECMWF GENERALLY REMAIN IN GOOD AGREEMENT
THROUGH THE EXTENDED PERIOD AND INDICATE A PERSISTENT UPPER TROUGH
CONTINUING TO INFLUENCE THE LOCAL AREA. ADDITIONALLY...A SURGE OF
DEEP LAYER MOISTURE LATER IN THE WEEK ASSOCIATED WITH A WEAK SURFACE
TROUGH EMBEDDED IN THE EASTERLY FLOW COMBINED WITH THE UPPER TROUGH
COULD LEAD TO MORE WIDESPREAD RAINFALL ACTIVITY EACH DAY WEDNESDAY
THROUGH FRIDAY. HOWEVER...WE WILL CONTINUE TO MONITOR LATER MODEL
TRENDS FOR CONSISTENCY OVER THE WEEKEND BEFORE INCREASING THE
RAINFALL CHANCES. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL EACH DAY.
AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS WILL CONTINUE ACROSS THE COASTAL
ATLANTIC WATERS THROUGH THE EARLY MORNING HOURS. LATEST HRRR AND
LOCAL MODELS INCREASE COVERAGE OF SHOWERS THROUGH THE MORNING AND
PUSH THEM INLAND ACROSS THE EAST COAST METRO AREAS UNDER WEAK
EASTERLY FLOW. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
MARINE...
LIGHT TO MODERATE EAST AND SOUTHEAST WINDS WILL CONTINUE THROUGH
MUCH OF THE FORECAST PERIOD AS HIGH PRESSURE REMAINS IN CONTROL
NORTHEAST OF THE MARINE AREA. ISOLATED OVERNIGHT AND EARLY MORNING
SHOWERS WILL REMAIN POSSIBLE EACH DAY ACROSS THE ATLANTIC WATERS.
FIRE WEATHER...
SOUTHEAST LOW-LEVEL WINDS ALONG WITH PLENTY OF LOW-LEVEL MOISTURE
WILL PERSIST THROUGH THE WEEKEND. MOST OF THE SHOWERS AND STORMS
THAT DEVELOP WILL BE FOCUSED ALONG THE EAST COAST THROUGH THE EARLY
MORNING HOURS AND ACROSS THE INTERIOR LOCATIONS THROUGH THE
AFTERNOON/EVENING PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 85 74 / 20 20 20 20
FORT LAUDERDALE 85 76 86 76 / 20 20 20 20
MIAMI 87 75 87 75 / 20 20 20 20
NAPLES 89 71 89 71 / 20 20 30 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE...59/MOLLEDA
AVIATION/RADAR/FIRE...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
740 AM EDT SAT MAY 18 2013
.AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS AND POSSIBLY A THUNDERSTORM OR
TWO WILL CONTINUE ACROSS THE COASTAL ATLANTIC WATERS THROUGH THE
MORNING HOURS. STILL EXPECT A FEW OF THESE SHOWERS TO PUSH INLAND
THROUGH THE LATE MORNING HOURS. THEREFORE...KEPT VCSH MENTION AT ALL
EAST COAST SITES. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
&&
.PREV DISCUSSION... /ISSUED 300 AM EDT SAT MAY 18 2013/
SHORT TERM (TODAY-MONDAY)...
ANOTHER WARM AND PLEASANT WEEKEND IS ANTICIPATED ACROSS SOUTH
FLORIDA WITH TEMPERATURES REMAINING AROUND TO SLIGHTLY ABOVE NORMAL
EACH DAY. THE LATEST NUMERICAL GUIDANCE REMAINS PERSISTENT AND IN
GOOD AGREEMENT DEPICTING AN UPPER RIDGE BUILDING EASTWARD OVER THE
MS VALLEY TRAILING A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW ALOFT. AS THIS SHORTWAVE ADVANCES E-SEWD OVER THE
STATE...UPPER HEIGHTS WILL SLIGHTLY FALL OVER THE STATE BY THE END
OF THE DAY. MODEL SOUNDINGS ACROSS THE NORTHERN AND INTERIOR
LOCATIONS OF THE LOCAL AREA REFLECT THIS AND INDICATE SOME MID-
LEVEL COOLING BY 00Z (H5 TEMPS AROUND -11C) WITH MID-LEVEL LAPSE
RATES STEEPENING (-6 TO -7 C/KM). THIS COMBINED WITH LIGHT
SOUTHEAST LOW-LEVEL FLOW...A SUFFICIENT AMOUNT OF LOW-LEVEL
MOISTURE AND DAYTIME HEATING WILL SUPPORT A FEW STORMS LATER TODAY
THROUGH THE LATE AFTERNOON/EARLY EVENING TIME FRAME. THE BEST
CHANCE FOR THIS ACTIVITY WILL BE ACROSS THE INTERIOR AND NORTHERN
LOCATIONS. THE FSU GRIDDED LIGHTNING PROBABILITY DATABASE AND THE
LATEST GRIDDED MOS THUNDERSTORM PROBABILITIES ARE GENERALLY
OUTPUTTING 20-40 PERCENT CHANCES OVER THESE INTERIOR LOCATIONS
THROUGH THIS TIME. THE MAIN LIMITING FACTORS FOR WIDESPREAD DEEP
MOIST CONVECTION WILL BE A PERSISTENT MID-LEVEL CAP BETWEEN 650 MB
AND 700 MB ALONG WITH PLENTY OF MID-LEVEL DRY AIR ENTRAINING INTO
ANY DEVELOPING CELLS. ANY STORM THAT DOES DEVELOP COULD BECOME
STRONG WITH THE MAIN IMPACTS BEING SMALL HAIL AND DAMAGING
STRAIGHT-LINE WINDS (40-55 MPH). THE LATEST HI-RES MODEL
REFLECTIVITIES BETWEEN THE WRF AND NAM GENERALLY LINE UP WELL AND
DEPICT SOME ACTIVITY INITIATING INLAND AND TOWARD THE NORTH AROUND
LAKE OKEECHOBEE THROUGH THE LATE AFTERNOON AND EARLY EVENING
PERIODS. SIMILAR CONDITIONS WILL PERSIST WITH THE EASTERLY LOW-
LEVEL FAVORING INTERIOR AFTERNOON ACTIVITY AGAIN ON SUNDAY AND
MONDAY. OVERNIGHT AND THROUGH THE EARLY MORNING HOURS EACH
DAY...SHOWERS AND A FEW STORMS ACROSS THE ATLANTIC WATERS AND THE
EAST COAST LOCATIONS WILL REMAIN POSSIBLE DUE TO THE CONFLUENT
BOUNDARIES SETTING UP DOWNSTREAM OF THE BAHAMAS AND RADIATIONAL
CLOUD-TOP COOLING.
LONG TERM (MONDAY NIGHT-FRIDAY)...
THE GFS/ENSEMBLE MEAN AND ECMWF GENERALLY REMAIN IN GOOD AGREEMENT
THROUGH THE EXTENDED PERIOD AND INDICATE A PERSISTENT UPPER TROUGH
CONTINUING TO INFLUENCE THE LOCAL AREA. ADDITIONALLY...A SURGE OF
DEEP LAYER MOISTURE LATER IN THE WEEK ASSOCIATED WITH A WEAK SURFACE
TROUGH EMBEDDED IN THE EASTERLY FLOW COMBINED WITH THE UPPER TROUGH
COULD LEAD TO MORE WIDESPREAD RAINFALL ACTIVITY EACH DAY WEDNESDAY
THROUGH FRIDAY. HOWEVER...WE WILL CONTINUE TO MONITOR LATER MODEL
TRENDS FOR CONSISTENCY OVER THE WEEKEND BEFORE INCREASING THE
RAINFALL CHANCES. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL EACH DAY.
AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS WILL CONTINUE ACROSS THE COASTAL
ATLANTIC WATERS THROUGH THE EARLY MORNING HOURS. LATEST HRRR AND
LOCAL MODELS INCREASE COVERAGE OF SHOWERS THROUGH THE MORNING AND
PUSH THEM INLAND ACROSS THE EAST COAST METRO AREAS UNDER WEAK
EASTERLY FLOW. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
MARINE...
LIGHT TO MODERATE EAST AND SOUTHEAST WINDS WILL CONTINUE THROUGH
MUCH OF THE FORECAST PERIOD AS HIGH PRESSURE REMAINS IN CONTROL
NORTHEAST OF THE MARINE AREA. ISOLATED OVERNIGHT AND EARLY MORNING
SHOWERS WILL REMAIN POSSIBLE EACH DAY ACROSS THE ATLANTIC WATERS.
FIRE WEATHER...
SOUTHEAST LOW-LEVEL WINDS ALONG WITH PLENTY OF LOW-LEVEL MOISTURE
WILL PERSIST THROUGH THE WEEKEND. MOST OF THE SHOWERS AND STORMS
THAT DEVELOP WILL BE FOCUSED ALONG THE EAST COAST THROUGH THE EARLY
MORNING HOURS AND ACROSS THE INTERIOR LOCATIONS THROUGH THE
AFTERNOON/EVENING PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 85 74 / 20 20 20 20
FORT LAUDERDALE 85 76 86 76 / 20 20 20 20
MIAMI 87 75 87 75 / 20 20 20 20
NAPLES 89 71 89 71 / 20 20 30 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...59/RM
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
300 AM EDT SAT MAY 18 2013
.SHORT TERM (TODAY-MONDAY)...
ANOTHER WARM AND PLEASANT WEEKEND IS ANTICIPATED ACROSS SOUTH
FLORIDA WITH TEMPERATURES REMAINING AROUND TO SLIGHTLY ABOVE NORMAL
EACH DAY. THE LATEST NUMERICAL GUIDANCE REMAINS PERSISTENT AND IN
GOOD AGREEMENT DEPICTING AN UPPER RIDGE BUILDING EASTWARD OVER THE
MS VALLEY TRAILING A SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHWEST
FLOW ALOFT. AS THIS SHORTWAVE ADVANCES E-SEWD OVER THE
STATE...UPPER HEIGHTS WILL SLIGHTLY FALL OVER THE STATE BY THE END
OF THE DAY. MODEL SOUNDINGS ACROSS THE NORTHERN AND INTERIOR
LOCATIONS OF THE LOCAL AREA REFLECT THIS AND INDICATE SOME MID-
LEVEL COOLING BY 00Z (H5 TEMPS AROUND -11C) WITH MID-LEVEL LAPSE
RATES STEEPENING (-6 TO -7 C/KM). THIS COMBINED WITH LIGHT
SOUTHEAST LOW-LEVEL FLOW...A SUFFICIENT AMOUNT OF LOW-LEVEL
MOISTURE AND DAYTIME HEATING WILL SUPPORT A FEW STORMS LATER TODAY
THROUGH THE LATE AFTERNOON/EARLY EVENING TIME FRAME. THE BEST
CHANCE FOR THIS ACTIVITY WILL BE ACROSS THE INTERIOR AND NORTHERN
LOCATIONS. THE FSU GRIDDED LIGHTNING PROBABILITY DATABASE AND THE
LATEST GRIDDED MOS THUNDERSTORM PROBABILITIES ARE GENERALLY
OUTPUTTING 20-40 PERCENT CHANCES OVER THESE INTERIOR LOCATIONS
THROUGH THIS TIME. THE MAIN LIMITING FACTORS FOR WIDESPREAD DEEP
MOIST CONVECTION WILL BE A PERSISTENT MID-LEVEL CAP BETWEEN 650 MB
AND 700 MB ALONG WITH PLENTY OF MID-LEVEL DRY AIR ENTRAINING INTO
ANY DEVELOPING CELLS. ANY STORM THAT DOES DEVELOP COULD BECOME
STRONG WITH THE MAIN IMPACTS BEING SMALL HAIL AND DAMAGING
STRAIGHT-LINE WINDS (40-55 MPH). THE LATEST HI-RES MODEL
REFLECTIVITIES BETWEEN THE WRF AND NAM GENERALLY LINE UP WELL AND
DEPICT SOME ACTIVITY INITIATING INLAND AND TOWARD THE NORTH AROUND
LAKE OKEECHOBEE THROUGH THE LATE AFTERNOON AND EARLY EVENING
PERIODS. SIMILAR CONDITIONS WILL PERSIST WITH THE EASTERLY LOW-
LEVEL FAVORING INTERIOR AFTERNOON ACTIVITY AGAIN ON SUNDAY AND
MONDAY. OVERNIGHT AND THROUGH THE EARLY MORNING HOURS EACH
DAY...SHOWERS AND A FEW STORMS ACROSS THE ATLANTIC WATERS AND THE
EAST COAST LOCATIONS WILL REMAIN POSSIBLE DUE TO THE CONFLUENT
BOUNDARIES SETTING UP DOWNSTREAM OF THE BAHAMAS AND RADIATIONAL
CLOUD-TOP COOLING.
.LONG TERM (MONDAY NIGHT-FRIDAY)...
THE GFS/ENSEMBLE MEAN AND ECMWF GENERALLY REMAIN IN GOOD AGREEMENT
THROUGH THE EXTENDED PERIOD AND INDICATE A PERSISTENT UPPER TROUGH
CONTINUING TO INFLUENCE THE LOCAL AREA. ADDITIONALLY...A SURGE OF
DEEP LAYER MOISTURE LATER IN THE WEEK ASSOCIATED WITH A WEAK SURFACE
TROUGH EMBEDDED IN THE EASTERLY FLOW COMBINED WITH THE UPPER TROUGH
COULD LEAD TO MORE WIDESPREAD RAINFALL ACTIVITY EACH DAY WEDNESDAY
THROUGH FRIDAY. HOWEVER...WE WILL CONTINUE TO MONITOR LATER MODEL
TRENDS FOR CONSISTENCY OVER THE WEEKEND BEFORE INCREASING THE
RAINFALL CHANCES. TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY ABOVE
NORMAL EACH DAY.
&&
.AVIATION...
ISOLATED LIGHT TO MODERATE SHOWERS WILL CONTINUE ACROSS THE COASTAL
ATLANTIC WATERS THROUGH THE EARLY MORNING HOURS. LATEST HRRR AND
LOCAL MODELS INCREASE COVERAGE OF SHOWERS THROUGH THE MORNING AND
PUSH THEM INLAND ACROSS THE EAST COAST METRO AREAS UNDER WEAK
EASTERLY FLOW. BEST CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH
THE PEAK HEATING HOURS OF THE DAY WILL BE ACROSS INTERIOR AND
WESTERN AREAS WITH A DEVELOPED GULF BREEZE. HOWEVER...CANNOT RULE
OUT AN ISOLATED THUNDERSTORM TO AFFECT THE EAST COAST TERMINALS THIS
AFTERNOON...BUT LEFT ANY THUNDER MENTION OUT OF TAFS FOR NOW.
&&
.MARINE...
LIGHT TO MODERATE EAST AND SOUTHEAST WINDS WILL CONTINUE THROUGH
MUCH OF THE FORECAST PERIOD AS HIGH PRESSURE REMAINS IN CONTROL
NORTHEAST OF THE MARINE AREA. ISOLATED OVERNIGHT AND EARLY MORNING
SHOWERS WILL REMAIN POSSIBLE EACH DAY ACROSS THE ATLANTIC WATERS.
&&
.FIRE WEATHER...
SOUTHEAST LOW-LEVEL WINDS ALONG WITH PLENTY OF LOW-LEVEL MOISTURE
WILL PERSIST THROUGH THE WEEKEND. MOST OF THE SHOWERS AND STORMS
THAT DEVELOP WILL BE FOCUSED ALONG THE EAST COAST THROUGH THE EARLY
MORNING HOURS AND ACROSS THE INTERIOR LOCATIONS THROUGH THE
AFTERNOON/EVENING PERIODS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 85 74 / 20 20 20 20
FORT LAUDERDALE 85 76 86 76 / 20 20 20 20
MIAMI 87 75 87 75 / 20 20 20 20
NAPLES 89 71 89 71 / 20 20 30 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1114 PM EDT SUN MAY 19 2013
.UPDATE...CONVECTION HAS FINALLY PUSHED SOUTH OF THE AREA BRINGING
PRECIP TO AN END AS WELL AS THE THREAT FOR ANY ADDITIONAL STRONG
OR SEVERE STORMS. HOWEVER...FLOODING CONTINUES WITH AREAL FLOOD
AND RIVER WARNINGS REPLACING FLASH FLOOD WARNINGS FROM EARLIER.
THERE COULD BE SOME ADDITIONAL RIVERS TO GO INTO FLOOD BUT NOTHING
TO WARRANT CONTINUATION OF FLOOD WATCH AND HAVE LET IT EXPIRE.
UPDATE WILL INCLUDE TRIMMING POPS FURTHER BUT REMAINING ELEMENTS
LOOK ON TRACK.
DEESE
&&
.PREV DISCUSSION... /ISSUED 750 PM EDT SUN MAY 19 2013/
PREV DISCUSSION... /ISSUED 312 PM EDT SUN MAY 19 2013/
SHORT TERM /TONIGHT THROUGH MONDAY/...
A RATHER MESSY UPPER LEVEL SYSTEM CONTINUES TO KEEP THE RISK OF
THUNDERSTORMS WITH HEAVY RAIN OVER MUCH OF THE CWA LATE THIS
AFTERNOON. REDEVELOPMENT OF THUNDERSTORMS ACROSS EASTERN TN/NORTH
GA IS REINFORCING THE FORECAST BY THE HRRR WHICH BRINGS ANOTHER
ROUND OT THUNDERSTORMS DOWN THE WEST SIDE OF GA THROUGH 00Z. THIS
WILL ALSO KEEP THE RISK OF FLASH FLOODING OVER THE WATCH AREA
THROUGH 00Z. THE PRECIP WILL SLOWLY EXIT FROM THE WEST TONIGHT
ALTHOUGH SOUTHEAST/EAST GA WILL STILL SEE SCATTERED
SHOWERS/TSTORMS INTO MONDAY. BY MONDAY AFTERNOON HIGH PRESSURE
WILL BE BUILDING OVER AL/GA WHICH SHOULD ALSO STABILIZE THE
ATMOSPHERE ENDING THE PRECIP BY MONDAY NIGHT/TUESDAY. MAV/MET
TEMPS LOOKING ALRIGHT...PERHAPS ON THE COOL SIDE TONIGHT AND HAVE
RAISE THEM A DEGREE OR TWO. WITH MORE SUNSHINE MONDAY
AFTERNOON...EXPECT TEMPS TO RISE WELL INTO THE 80S MOST AREAS.
17
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
VERY FEW CHANGES TO THE EXTENDED. MADE SOME ADJUSTMENTS TO TEMPS
ON SATURDAY TO ACCOUNT FOR DRY CAD PROGGED TO DEVELOP. 12Z RUNS OF
GFS AND ECMWF STILL SIMILAR FOR THE SYSTEM AT THE END OF THE WEEK WITH
VERY LITTLE PRECIP EXPECTED AND THE FRONT MOVING THROUGH SOMETIME
EARLY FRIDAY. ALSO INCREASED CLOUD COVER A LITTLE FOR THE
WEDNESDAY SYSTEM AND ADJUSTED TEMPS ACCORDINGLY THERE AS
WELL...OTHERWISE NO SIGNIFICANT CHANGES.
TDP
PREV DISCUSSION... /ISSUED 357 AM EDT SUN MAY 19 2013/
PRECIP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE
TROUGH SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS
DURING THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
NLISTEMAA
AVIATION...
00Z UPDATE...
FIRST WAVE OF CONVECTION PUSHED SOUTH OF THE TERMINALS AND NEXT
WAVE HAS NOW DISSIPATED PRIOR TO ARRIVAL. THIS SHOULD LEAVE ALL
THE TERMINALS EXCEPT CSG AND MCN WITH JUST RESIDUAL -RA. CSG COULD
STILL SEE UPSTREAM CONVECTION OVER AL IMPACT THE TERMINAL THROUGH
06Z WITH MUCH LESSER CHANCES OVER MCN. OTHERWISE...REMAINS A
CHALLENGING FORECAST WITH CIGS THE BIG QUESTION AND UNCERTAINTY IS
GREAT WITH THE GUIDANCE. WITH THE AMOUNT OF RAIN MOST AREAS HAVE
SEEN...LEANING TOWARD THE MORE PESSIMISTIC PROJECTIONS OF IFR
DEVELOPMENT AT THE TERMINALS TONIGHT. WINDS WILL CONTINUE TO BE
TROUBLESOME AT ATL WITH MOST ACTIVITY OUTFLOW DRIVEN ALLOWING FOR
RAPID FLUCTUATIONS IN DIRECTIONS. WILL MAINTAIN LIGHT NORTHEAST
INITIALLY FOLLOWED BY LIGHT AND VARIABLE OVERNIGHT TONIGHT.
//ATL CONFIDENCE...00Z UPDATE...
LOW TO MEDIUM ON CIGS AND WINDS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 63 86 65 86 / 80 20 10 30
ATLANTA 66 86 67 85 / 70 10 10 30
BLAIRSVILLE 60 83 60 82 / 70 10 10 40
CARTERSVILLE 63 87 65 87 / 80 10 10 20
COLUMBUS 66 89 67 89 / 80 10 10 10
GAINESVILLE 63 83 65 83 / 80 10 10 40
MACON 66 87 65 88 / 40 20 20 20
ROME 63 88 64 87 / 80 10 10 20
PEACHTREE CITY 64 86 65 86 / 70 10 10 20
VIDALIA 68 88 67 87 / 40 50 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....11
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
750 PM EDT SUN MAY 19 2013
.PREV DISCUSSION... /ISSUED 312 PM EDT SUN MAY 19 2013/
SHORT TERM /TONIGHT THROUGH MONDAY/...
A RATHER MESSY UPPER LEVEL SYSTEM CONTINUES TO KEEP THE RISK OF
THUNDERSTORMS WITH HEAVY RAIN OVER MUCH OF THE CWA LATE THIS
AFTERNOON. REDEVELOPMENT OF THUNDERSTORMS ACROSS EASTERN TN/NORTH
GA IS REINFORCING THE FORECAST BY THE HRRR WHICH BRINGS ANOTHER
ROUND OT THUNDERSTORMS DOWN THE WEST SIDE OF GA THROUGH 00Z. THIS
WILL ALSO KEEP THE RISK OF FLASH FLOODING OVER THE WATCH AREA
THROUGH 00Z. THE PRECIP WILL SLOWLY EXIT FROM THE WEST TONIGHT
ALTHOUGH SOUTHEAST/EAST GA WILL STILL SEE SCATTERED
SHOWERS/TSTORMS INTO MONDAY. BY MONDAY AFTERNOON HIGH PRESSURE
WILL BE BUILDING OVER AL/GA WHICH SHOULD ALSO STABILIZE THE
ATMOSPHERE ENDING THE PRECIP BY MONDAY NIGHT/TUESDAY. MAV/MET
TEMPS LOOKING ALRIGHT...PERHAPS ON THE COOL SIDE TONIGHT AND HAVE
RAISE THEM A DEGREE OR TWO. WITH MORE SUNSHINE MONDAY
AFTERNOON...EXPECT TEMPS TO RISE WELL INTO THE 80S MOST AREAS.
17
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
VERY FEW CHANGES TO THE EXTENDED. MADE SOME ADJUSTMENTS TO TEMPS
ON SATURDAY TO ACCOUNT FOR DRY CAD PROGGED TO DEVELOP. 12Z RUNS OF
GFS AND ECMWF STILL SIMILAR FOR THE SYSTEM AT THE END OF THE WEEK WITH
VERY LITTLE PRECIP EXPECTED AND THE FRONT MOVING THROUGH SOMETIME
EARLY FRIDAY. ALSO INCREASED CLOUD COVER A LITTLE FOR THE
WEDNESDAY SYSTEM AND ADJUSTED TEMPS ACCORDINGLY THERE AS
WELL...OTHERWISE NO SIGNIFICANT CHANGES.
TDP
PREV DISCUSSION... /ISSUED 357 AM EDT SUN MAY 19 2013/
PRECIP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE
TROUGH SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS
DURING THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
NLISTEMAA
&&
.AVIATION...
00Z UPDATE...
FIRST WAVE OF CONVECTION PUSHED SOUTH OF THE TERMINALS AND NEXT
WAVE HAS NOW DISSIPATED PRIOR TO ARRIVAL. THIS SHOULD LEAVE ALL
THE TERMINALS EXCEPT CSG AND MCN WITH JUST RESIDUAL -RA. CSG COULD
STILL SEE UPSTREAM CONVECTION OVER AL IMPACT THE TERMINAL THROUGH
06Z WITH MUCH LESSER CHANCES OVER MCN. OTHERWISE...REMAINS A
CHALLENGING FORECAST WITH CIGS THE BIG QUESTION AND UNCERTAINTY IS
GREAT WITH THE GUIDANCE. WITH THE AMOUNT OF RAIN MOST AREAS HAVE
SEEN...LEANING TOWARD THE MORE PESSIMISTIC PROJECTIONS OF IFR
DEVELOPMENT AT THE TERMINALS TONIGHT. WINDS WILL CONTINUE TO BE
TROUBLESOME AT ATL WITH MOST ACTIVITY OUTFLOW DRIVEN ALLOWING FOR
RAPID FLUCTUATIONS IN DIRECTIONS. WILL MAINTAIN LIGHT NORTHEAST
INITIALLY FOLLOWED BY LIGHT AND VARIABLE OVERNIGHT TONIGHT.
//ATL CONFIDENCE...00Z UPDATE...
LOW TO MEDIUM ON CIGS AND WINDS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 63 86 65 86 / 80 20 10 30
ATLANTA 66 86 67 85 / 50 10 10 30
BLAIRSVILLE 60 83 60 82 / 80 10 10 40
CARTERSVILLE 63 87 65 87 / 80 10 10 20
COLUMBUS 66 89 67 89 / 30 10 10 10
GAINESVILLE 63 83 65 83 / 80 10 10 40
MACON 66 87 65 88 / 50 20 20 20
ROME 63 88 64 87 / 80 10 10 20
PEACHTREE CITY 64 86 65 86 / 40 10 10 20
VIDALIA 68 88 67 87 / 50 50 40 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES:
BALDWIN...BANKS...BARROW...BARTOW...BIBB...BUTTS...CARROLL...
CATOOSA...CHATTOOGA...CHEROKEE...CLARKE...CLAYTON...COBB...
COWETA...CRAWFORD...DADE...DAWSON...DEKALB...DOUGLAS...FANNIN...
FAYETTE...FLOYD...FORSYTH...GILMER...GLASCOCK...GORDON...
GREENE...GWINNETT...HALL...HANCOCK...HARALSON...HEARD...HENRY...
JACKSON...JASPER...JEFFERSON...JONES...LAMAR...LUMPKIN...
MADISON...MERIWETHER...MONROE...MORGAN...MURRAY...NEWTON...NORTH
FULTON...OCONEE...OGLETHORPE...PAULDING...PICKENS...PIKE...
POLK...PUTNAM...ROCKDALE...SOUTH FULTON...SPALDING...
TALIAFERRO...TOWNS...TROUP...UNION...UPSON...WALKER...WALTON...
WARREN...WASHINGTON...WHITE...WHITFIELD...WILKES...WILKINSON.
&&
$$
SHORT TERM...DEESE
LONG TERM....11
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
535 PM EDT SAT MAY 18 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL GRADUALLY MOVE INTO THE AREA SUNDAY
INTO TUESDAY...THEN WILL STALL AND DISSIPATE AS ATLANTIC HIGH PRESSURE
BECOMES THE DOMINANT FEATURE THROUGH MUCH OF NEXT WEEK. A COLD FRONT
WILL APPROACH THE REGION BY NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
LATE THIS AFTERNOON...CONVECTION HAS DRIFTED SLOWLY TO THE EAST
OVER THE PAST HOUR OR TWO AND HAS NOTICEABLY WEAKENED. MUCH OF THIS
IS DUE TO DWINDLING MLCAPE AND THE HIGH CLOUDS SPAWNED BY THESE
THUNDERSTORMS WILL CONTINUE TO INHIBIT DESTABILIZATION DOWNSTREAM.
THE UPDATED POPS FAVOR THE 18/19Z HRRR WHICH SHOWS THE CURRENT
CONVECTION DISSIPATING IN PLACE. ALSO UPDATED HOURLY TEMPS WHICH
SHOW SIGNIFICANT SPATIAL VARIABILITY THANKS TO RAIN COOLED AIR AND
THUNDERSTORM OUTFLOW.
TONIGHT...WITH THE LOSS OF AFTERNOON HEATING ANY REMAINING
SHOWER/STORM ACTIVITY WILL DECREASE THIS EVENING. THROUGH THE
OVERNIGHT...THE BAGGY UPPER TROUGH ALOFT WILL CONTINUE TO MEANDER
AROUND JUST TO THE NORTH AND NORTHWEST OF THE FORECAST AREA. A
PERUSAL OF MODEL SOUNDINGS SHOWS CONTINUED MOISTENING AND THE
PRESENCE OF ELEVATED INSTABILITY THROUGH DAYBREAK. IN
FACT...SHOWALTERS GO TO AROUND -1 OR -2. MANY OF THE SUITE OF
MODELS DEPICTS SHOWER/STORM COVERAGE INCREASING LATE ACROSS MUCH
OF THE AREA AND STREAMING IN FROM OFFSHORE. POPS SHOW A DECREASING
TREND THROUGH THE EVENING AND THEN RAMP BACK UP TO CHANCE TOWARDS
SUNRISE. PLENTIFUL CLOUD COVER AND WARM SOUTHERLY FLOW WILL KEEP
LOWS IN THE MID/UPPER 60S IN MOST AREAS.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
THE UPSTREAM SHORTWAVE TROUGH WILL SETTLE INTO THE REGION SUNDAY
THROUGH MONDAY...THEN WILL STALL AND SLOWLY UNRAVEL/WEAKEN OVER THE
REGION BY THE END OF THE FORECAST PERIOD. THE OVERALL REGIME WILL
FAVOR SCATTERED TO NUMEROUS SHOWERS/THUNDERSTORMS...SIGNIFICANT
CLOUD COVER AND TEMPERATURES NOT EXCEEDING THE LOWER TO MID 80S AT
MOST LOCALES. OF GREATEST INTEREST...LOCALLY HEAVY RAINFALL IS
POSSIBLE GIVEN PWATS INCREASING TO BETWEEN 1.5 AND 1.8 INCHES/
1 TO 3 STANDARD DEVIATIONS ABOVE NORMAL FOR MID-MAY AND MULTICELL
CONVECTION WITHIN A RELATIVELY WEAK STEERING FLOW REGIME/MODULATED
BY MESOSCALE BOUNDARIES.
GIVEN THE COMPLEX CONVECTIVE SCENARIO...FORECAST DETAILS WILL REMAIN
VERY DIFFICULT TO PIN DOWN BEYOND THE NEAR TERM FORECAST PERIOD. IN
GENERAL...PRECIPITATION COVERAGE SHOULD GENERALLY INCREASE PER
DIURNAL WARMING/DESTABILIZATION EACH AFTERNOON/EVENING. THE GREATEST
POTENTIAL COVERAGE WILL SUNDAY AND MONDAY PM...THEN DIURNAL
PRECIPITATION COVERAGE SHOULD BE RELATIVELY MORE SPARSE TUESDAY PM
DUE TO BUILDING HEIGHTS ALOFT AND AN ASSOCIATED WEAKENING OF THE
MID/UPPER VORTICITY MAXIMUM. HOWEVER...THE DEGREE OF DIURNAL
WARMING/DESTABILIZATION WILL DEPEND ON CLOUD COVER/ANTECEDENT
PRECIPITATION. INDEED...UPSTREAM/CLOSER TO THE UPPER LOW SATURDAY
AFTERNOON EARLIER PRECIPITATION AND LINGERING CLOUD COVER HELD
TEMPERATURES IN THE 70S AND HAD LIMITED COVERAGE/INTENSITY OF
PRECIPITATION...AND THIS SCENARIO CANNOT BE RULED OUT IN OUR AREA
SUNDAY/MONDAY.
OTHERWISE...CANNOT RULE OUT SHOWERS/THUNDERSTORMS AT ANY TIME
THROUGH THE PERIOD. FOR EXAMPLE...18/12Z GUIDANCE GENERALLY
INDICATES AN INCREASE IN DEEP LAYER MOISTURE AND AN ASSOCIATED
INCREASE IN SHOWER COVERAGE OVERNIGHT SUNDAY NIGHT/EARLY
MONDAY...ESPECIALLY ACROSS NORTHERN/EASTERN COUNTIES. WHILE
CONFIDENCE IN THIS SCENARIO IS NOT NECESSARILY HIGH...MODEL TRENDS
JUSTIFY AN INCREASE IN POPS OVERNIGHT SUNDAY NIGHT INTO EARLY
MONDAY. FURTHER...OTHERWISE...HIGHEST POPS ARE CAPPED IN THE HIGH
CHANCE/LOW LIKELY CATEGORY INLAND DURING THE SUNDAY/MONDAY PM
PERIOD...BUT SIGNIFICANT REFINEMENTS WILL BE REQUIRED WITHIN
SUBSEQUENT FORECAST PACKAGES.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A RATHER WARM PATTERN PERSISTS IN THE LONG TERM AS THE AREA SITS ON
THE WESTERN SIDE OF AN UPPER RIDGE WITH ATLANTIC HIGH PRESSURE
OFFSHORE. RAIN CHANCES WILL INCREASE A BIT LATE IN THE WEEK AS AN
UPPER TROUGH APPROACHES FROM THE WEST AND A COLD FRONT DROPS INTO
THE AREA FRIDAY NIGHT OR SATURDAY.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
AT KSAV...THE AIRFIELD DID RECEIVE A GLANCING BLOW FROM A
WEAKENING THUNDERSTORM WHICH BRIEFLY CAUSED VISIBILITY REDUCTIONS.
BASED ON CURRENT RADAR IT APPEARS THAT THUNDERSTORMS WILL REMAIN
IN THE VICINITY OF THE AIRFIELD THROUGH ABOUT 23Z BEFORE
COMPLETELY DISSIPATING. THEN OVERNIGHT...MODEL GUIDANCE SHOWS THE
POTENTIAL FOR DEVELOPING MVFR CEILINGS LATE WHICH THEN CONTINUES
THROUGH MUCH OF THE MORNING. STILL NOT CONFIDENT ENOUGH TO
ADVERTISE PREVAILING MVFR CONDITIONS SO I HAVE JUST ADDED A
MENTION OF SCATTERED MVFR LEVEL CLOUDS.
AT KCHS...AFTERNOON THUNDERSTORMS ARE EXPECTED TO REMAIN WEST OF
THE AREA. THE MAIN THING TO KEEP AN EYE ON IS THE OVERNIGHT PERIOD
WHEN MUCH OF THE MODEL GUIDANCE SHOWS ISOLATED/SCATTERED SHOWERS
DEVELOPING ALONG THE SC COASTLINE WITHIN SOME WEAK CONVERGENCE. I
HAVE INTRODUCED VCSH STARTING AT 09Z AND WITH ANY SHOWERS THAT DO
DEVELOP MVFR CEILINGS ARE POSSIBLE.
EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. DIRECT/TRANSIENT IMPACTS
INCLUDING FLIGHT RESTRICTIONS FROM ISOLATED TO SCATTERED
SHOWERS/THUNDERSTORMS WILL LIKELY OCCUR THROUGH EARLY NEXT WEEK.
&&
.MARINE...
TONIGHT...NO CHANGE TO THE SETUP WITH ATLANTIC HIGH PRESSURE DRIVING
PERSISTENT S TO SE FLOW. WIND SPEEDS WILL REMAIN AT OR BELOW 15 KTS
WITH SEAS 2-4 FT.
PERSISTENT ATLANTIC HIGH PRESSURE WILL PRODUCE SOUTH TO SOUTHEAST
WINDS RANGING FROM 10 TO 15 KNOTS...WITH LOCALLY/BRIEFLY STRONGER
ONSHORE WINDS AS HIGH AS 20 KT DUE TO THE DIURNAL SEA BREEZE
CIRCULATION EACH DAY. SEAS WILL AVERAGE 2 TO 4 FEET MUCH OF THE
TIME...ALTHOUGH SEAS AS HIGH AS 5-6 FT COULD BEGIN TO IMPINGE UPON
WATERS BEYOND 20 NM BY MID TO LATE WEEK.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...BSH
SHORT TERM...SPR
LONG TERM...JRL
AVIATION...BSH
MARINE...BSH/SPR
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
138 PM EDT SAT MAY 18 2013
.PREV DISCUSSION... /ISSUED 438 AM EDT SAT MAY 18 2013/
SHORT TERM /TODAY THROUGH SUNDAY/...
COMPLEX AND DIFFICULT FORECAST THE NEXT 24 TO 36 HOURS. SLOW MOVING
AND WEAK UPPER LEVEL LOW NOTED IN WATER VAPOR OVER CENTRAL TN
RESPONSIBLE FOR SHOWERS AND A FEW STORMS MOVING INTO WESTERN GA NOW
THROUGH SAT AM. MODELS CONTINUE TO KEEP THE REGION IN A GENERAL
NORTHWEST FLOW PATTERN THROUGH SUNDAY WITH WEAK DISTURBANCES MOVING
SOUTHEAST ON THE SOUTHWEST SIDE OF THE WEAK UPPER LOW. ALL OF THE
MODELS AGREE ON CHANCE TO LIKELY POPS FOR A PORTION OF THE AREA BUT
DISAGREE ON EXACT LOCATION AND TIMING...MOST LIKELY DUE TO
DIFFICULTIES RESOLVING THESE FEATURES. FOR TODAY...BIG QUESTION
WITH THIS ONGOING ACTIVITY IS HOW MUCH CLOUD DEBRIS WILL REMAIN AND
HINDER OR DELAY ANY DAYTIME HEATING ACROSS GA AND THE ONSET OF
THUNDERSTORM DEVELOPMENT. HRRR AND HIGH RES WRF CONTINUE TO SHOW
SHOWERS THROUGH MORNING WITH MORE SCATTERED CONVECTION DEVELOPING
THIS AFTERNOON. AS A RESULT...HAVE OPTED TO MAINTAIN SOME
CONSISTENCY WITH THE PREVIOUS FORECAST WHICH SHOWS HIGHEST POPS
ACROSS NORTHERN GA THROUGH SAT AND LESSER POPS ACROSS THE SOUTHERN
TIER. WILL HAVE TO WATCH THE SOUTHERN TIER OF COUNTIES AS
DIFFERENTIAL HEATING MAY HAVE A BIGGER THAN CURRENT MODELS
FORECASTING GIVEN THE LOCATION OF THE CURRENT ACTIVITY.
WILL HAVE TO WATCH AREA SAT NIGHT INTO SUNDAY AS SEVERAL MODELS ARE
HINTING AT SOME TYPE OF MCS DEVELOPMENT IN NORTHERN AL AND TN.
GIVEN THE NORTHWEST FLOW AND THESE DISTURBANCES...CANT RULE IT OUT.
GFS INSTABILITY FORECAST FOR SUNDAY IS IMPRESSIVE WITH 500 TO 700 MB
LAPSE RATES OVER 8 DEG C/KM FOR NORTHWEST GA. ALONG WITH CAPE
VALUES 2000 TO AS MUCH AS 4000 J/KG ... THERE WILL BE SOME SEVERE
POTENTIAL...HOWEVER SHEAR VALUES ARE LESS THAN MARGINAL SO
CONFIDENCE ON A MORE WIDESPREAD SEVERE EVENT IS LESS. MAIN IMPACTS
WILL BE DAMAGING WINDS AND HAIL. TIMING OF STORMS ON SUNDAY IS A
CRAP SHOOT AT THIS POINT AND MODEL TIMING IS ALL OVER THE PLACE
GIVEN THE POTENTIAL MCS DEVELOPMENT EARLY ON SUN. NEEDLESS TO
SAY...WILL NEED TO WATCH THE FORECAST CLOSELY THROUGH THE WEEKEND AS
IT COULD CHANGE SIGNIFICANTLY FOR BETTER OR WORSE.
HIGH PW VALUES AND THE SLOW MOVING NATURE OF THESE DISTURBANCES HAVE
THE POTENTIAL TO PRODUCE SOME ISOLATED FLASH FLOODING...PARTICULARLY
ACROSS NORTH GA BOTH SAT AND SUN. WILL NEED TO ALSO MONITOR THIS AS
WELL AS THE SEVERE THREAT.
30
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA. MODELS
ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND AFFECTING
THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP LAPSE RATES WILL
HELP SUSTAIN CONVECTION AND CONTINUE THE POSSIBILITY OF SEVERE
STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
&&
.AVIATION...
18Z UPDATE...
MVFR CIGS ACROSS ATL/AHN AREAS SHOULD CONTINUE TO LIFT WITH AREAS
GOING VFR BY 21Z AND REMAINING VFR UNTIL LATE TONIGHT. SCATTERED
CONVECTION WILL BE POSSIBLE THROUGH THE AFTERNOON. ANY CONVECTION
THAT DOES DEVELOP SHOULD DIMINISH TO SHOWERS LATE THIS EVENING. A
SECOND SHORT WAVE WILL MOVE INTO NORTH GA LATE TONIGHT AND SPREAD
INTO CENTRAL GA SUNDAY BRINGING AN INCREASING CHANCE OF CONVECTION
THROUGH THE DAY. WINDS WILL REMAIN SOUTHWEST LESS THAN 10KTS THROUGH
THE FORECAST.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS ON CIGS/VSBYS.
LOW TO MEDIUM ON TIMING OF CONVECTION.
17
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 80 63 79 65 / 60 60 60 60
ATLANTA 78 65 79 66 / 70 70 60 60
BLAIRSVILLE 73 60 76 60 / 70 70 70 70
CARTERSVILLE 78 63 79 65 / 70 70 60 50
COLUMBUS 83 67 85 67 / 90 50 40 50
GAINESVILLE 76 63 76 63 / 70 70 70 60
MACON 85 64 84 66 / 50 50 60 60
ROME 79 63 81 65 / 70 70 60 40
PEACHTREE CITY 79 64 79 65 / 60 60 60 60
VIDALIA 88 69 87 68 / 40 40 60 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
747 AM EDT SAT MAY 18 2013
.PREV DISCUSSION... /ISSUED 438 AM EDT SAT MAY 18 2013/
SHORT TERM /TODAY THROUGH SUNDAY/...
COMPLEX AND DIFFICULT FORECAST THE NEXT 24 TO 36 HOURS. SLOW MOVING
AND WEAK UPPER LEVEL LOW NOTED IN WATER VAPOR OVER CENTRAL TN
RESPONSIBLE FOR SHOWERS AND A FEW STORMS MOVING INTO WESTERN GA NOW
THROUGH SAT AM. MODELS CONTINUE TO KEEP THE REGION IN A GENERAL
NORTHWEST FLOW PATTERN THROUGH SUNDAY WITH WEAK DISTURBANCES MOVING
SOUTHEAST ON THE SOUTHWEST SIDE OF THE WEAK UPPER LOW. ALL OF THE
MODELS AGREE ON CHANCE TO LIKELY POPS FOR A PORTION OF THE AREA BUT
DISAGREE ON EXACT LOCATION AND TIMING...MOST LIKELY DUE TO
DIFFICULTIES RESOLVING THESE FEATURES. FOR TODAY...BIG QUESTION
WITH THIS ONGOING ACTIVITY IS HOW MUCH CLOUD DEBRIS WILL REMAIN AND
HINDER OR DELAY ANY DAYTIME HEATING ACROSS GA AND THE ONSET OF
THUNDERSTORM DEVELOPMENT. HRRR AND HIGH RES WRF CONTINUE TO SHOW
SHOWERS THROUGH MORNING WITH MORE SCATTERED CONVECTION DEVELOPING
THIS AFTERNOON. AS A RESULT...HAVE OPTED TO MAINTAIN SOME
CONSISTENCY WITH THE PREVIOUS FORECAST WHICH SHOWS HIGHEST POPS
ACROSS NORTHERN GA THROUGH SAT AND LESSER POPS ACROSS THE SOUTHERN TIER.
WILL HAVE TO WATCH THE SOUTHERN TIER OF COUNTIES AS DIFFERENTIAL
HEATING MAY HAVE A BIGGER THAN CURRENT MODELS FORECASTING GIVEN THE
LOCATION OF THE CURRENT ACTIVITY.
WILL HAVE TO WATCH AREA SAT NIGHT INTO SUNDAY AS SEVERAL MODELS ARE
HINTING AT SOME TYPE OF MCS DEVELOPMENT IN NORTHERN AL AND TN. GIVEN
THE NORTHWEST FLOW AND THESE DISTURBANCES...CANT RULE IT OUT. GFS
INSTABILITY FORECAST FOR SUNDAY IS IMPRESSIVE WITH 500 TO 700 MB
LAPSE RATES OVER 8 DEG C/KM FOR NORTHWEST GA. ALONG WITH CAPE
VALUES 2000 TO AS MUCH AS 4000 J/KG ... THERE WILL BE SOME SEVERE
POTENTIAL...HOWEVER SHEAR VALUES ARE LESS THAN MARGINAL SO
CONFIDENCE ON A MORE WIDESPREAD SEVERE EVENT IS LESS. MAIN IMPACTS
WILL BE DAMAGING WINDS AND HAIL. TIMING OF STORMS ON SUNDAY IS A
CRAP SHOOT AT THIS POINT AND MODEL TIMING IS ALL OVER THE PLACE
GIVEN THE POTENTIAL MCS DEVELOPMENT EARLY ON SUN. NEEDLESS TO
SAY...WILL NEED TO WATCH THE FORECAST CLOSELY THROUGH THE WEEKEND AS
IT COULD CHANGE SIGNIFICANTLY FOR BETTER OR WORSE.
HIGH PW VALUES AND THE SLOW MOVING NATURE OF THESE DISTURBANCES HAVE
THE POTENTIAL TO PRODUCE SOME ISOLATED FLASH FLOODING...PARTICULARLY
ACROSS NORTH GA BOTH SAT AND SUN. WILL NEED TO ALSO MONITOR THIS AS
WELL AS THE SEVERE THREAT.
30
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA. MODELS
ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND AFFECTING
THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP LAPSE RATES WILL
HELP SUSTAIN CONVECTION AND CONTINUE THE POSSIBILITY OF SEVERE
STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
AVIATION...
06Z UPDATE...
SHOWERS AND A FEW EMBEDDED TSTORMS WORKING EAST OUT OF AL INTO GA
TONIGHT. TIME OF ARRIVAL ON MAIN CELLS FOR ATLANTA AREA SITES
BETWEEN 07Z AND 08Z BUT AM NOT CONFIDENT THEY WILL HOLD TOGETHER
AS AIRMASS IS A LITTLE MORE STABLE ACROSS GA. THIS IS EVIDENT IN THE
LARGER CELL WEST OF CSG WHICH HAS BEEN WEAKENING AS IT MOVES EAST.
DID INCLUDE TSRA IN A TEMPO GROUP AT ATL OVERNIGHT FOR SOME OF THE
STRONGER CELLS. HRRR AND HIGH RES MODELS CONTINUE TO SHOW THE EAST WEST
BANDING OF STORMS THROUGH MID MORNING BUT PRIMARILY OVER AL AND
EXTREME WESTERN GA. WILL NEED TO MONITOR THIS FOR ANY SLIGHT
EASTWARD EXTENSION AND THE NEED TO AMD WITH THUNDER.
OTHERWISE...BELIEVE CLOUD DEBRIS WILL HAMPER EARLY TS DEVELOPMENT
ON SAT BUT STILL THINK TSTORMS WILL DEVELOP IN THE AFTERNOON
PARTICULARLY ACROSS NORTH GA. MVFR CIGS AND VSBYS ARE POSSIBLE
OVERNIGHT PARTICULARLY IN SHOWERS MAINLY BETWEEN 08Z AND 12Z AND
WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT OUT OF THE SOUTHWEST
BUT INCREASING TO AROUND 10KTS AFTER 16Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS
30
&&
.AVIATION...
12Z UPDATE...
MADE SOME CHANGES IN THE TAF BASED ON THE SHORT TERM TRENDS TO
OPEN UP A MORE RAIN FREE WINDOW FROM AROUND 15Z THROUGH EARLY
AFTERNOON. EXPECT THE RAIN COOLED AIR TO STABILIZE THE ATMSPHERE
FOR A FEW HOURS BEFORE STORMS BEGIN TO REDEVELOP THIS AFTERNOON.
HRRR AND WRF SUPPORT NEW DEVELOPMENT AROUND 20Z ACROSS NORTH GA
HOWEVER COVERAGE IS IN QUESTION AT THIS POINT. WINDS AND CIGS
CONSISTENT WITH PREVIOUS DISCUSSION.
//ATL CONFIDENCE...12Z UPDATE...
CONFIDENCE MEDIUM ON CIGS...VSBY.
CONFIDENCE LOW ON PRECIP TIMING.
30
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 80 63 79 65 / 60 60 60 60
ATLANTA 78 65 79 66 / 70 70 60 60
BLAIRSVILLE 73 60 76 60 / 70 70 70 70
CARTERSVILLE 78 63 79 65 / 70 70 60 50
COLUMBUS 83 67 85 67 / 90 50 40 50
GAINESVILLE 76 63 76 63 / 70 70 70 60
MACON 85 64 84 66 / 50 50 60 60
ROME 79 63 81 65 / 70 70 60 40
PEACHTREE CITY 79 64 79 65 / 60 60 60 60
VIDALIA 88 69 87 68 / 40 40 60 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
438 AM EDT SAT MAY 18 2013
.SHORT TERM /TODAY THROUGH SUNDAY/...
COMPLEX AND DIFFICULT FORECAST THE NEXT 24 TO 36 HOURS. SLOW MOVING
AND WEAK UPPER LEVEL LOW NOTED IN WATER VAPOR OVER CENTRAL TN
RESPONSIBLE FOR SHOWERS AND A FEW STORMS MOVING INTO WESTERN GA NOW
THROUGH SAT AM. MODELS CONTINUE TO KEEP THE REGION IN A GENERAL
NORTHWEST FLOW PATTERN THROUGH SUNDAY WITH WEAK DISTURBANCES MOVING
SOUTHEAST ON THE SOUTHWEST SIDE OF THE WEAK UPPER LOW. ALL OF THE
MODELS AGREE ON CHANCE TO LIKELY POPS FOR A PORTION OF THE AREA BUT
DISAGREE ON EXACT LOCATION AND TIMING...MOST LIKELY DUE TO
DIFFICULTIES RESOLVING THESE FEATURES. FOR TODAY...BIG QUESTION
WITH THIS ONGOING ACTIVITY IS HOW MUCH CLOUD DEBRIS WILL REMAIN AND
HINDER OR DELAY ANY DAYTIME HEATING ACROSS GA AND THE ONSET OF
THUNDERSTORM DEVELOPMENT. HRRR AND HIGH RES WRF CONTINUE TO SHOW
SHOWERS THROUGH MORNING WITH MORE SCATTERED CONVECTION DEVELOPING
THIS AFTERNOON. AS A RESULT...HAVE OPTED TO MAINTAIN SOME
CONSISTENCY WITH THE PREVIOUS FORECAST WHICH SHOWS HIGHEST POPS
ACROSS NORTHERN GA THROUGH SAT AND LESSER POPS ACROSS THE SOUTHERN TIER.
WILL HAVE TO WATCH THE SOUTHERN TIER OF COUNTIES AS DIFFERENTIAL
HEATING MAY HAVE A BIGGER THAN CURRENT MODELS FORECASTING GIVEN THE
LOCATION OF THE CURRENT ACTIVITY.
WILL HAVE TO WATCH AREA SAT NIGHT INTO SUNDAY AS SEVERAL MODELS ARE
HINTING AT SOME TYPE OF MCS DEVELOPMENT IN NORTHERN AL AND TN. GIVEN
THE NORTHWEST FLOW AND THESE DISTURBANCES...CANT RULE IT OUT. GFS
INSTABILITY FORECAST FOR SUNDAY IS IMPRESSIVE WITH 500 TO 700 MB
LAPSE RATES OVER 8 DEG C/KM FOR NORTHWEST GA. ALONG WITH CAPE
VALUES 2000 TO AS MUCH AS 4000 J/KG ... THERE WILL BE SOME SEVERE
POTENTIAL...HOWEVER SHEAR VALUES ARE LESS THAN MARGINAL SO
CONFIDENCE ON A MORE WIDESPREAD SEVERE EVENT IS LESS. MAIN IMPACTS
WILL BE DAMAGING WINDS AND HAIL. TIMING OF STORMS ON SUNDAY IS A
CRAP SHOOT AT THIS POINT AND MODEL TIMING IS ALL OVER THE PLACE
GIVEN THE POTENTIAL MCS DEVELOPMENT EARLY ON SUN. NEEDLESS TO
SAY...WILL NEED TO WATCH THE FORECAST CLOSELY THROUGH THE WEEKEND AS
IT COULD CHANGE SIGNIFICANTLY FOR BETTER OR WORSE.
HIGH PW VALUES AND THE SLOW MOVING NATURE OF THESE DISTURBANCES HAVE
THE POTENTIAL TO PRODUCE SOME ISOLATED FLASH FLOODING...PARTICULARLY
ACROSS NORTH GA BOTH SAT AND SUN. WILL NEED TO ALSO MONITOR THIS AS
WELL AS THE SEVERE THREAT.
30
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
HAVE ADJUSTED POPS UPWARD FOR SUNDAY NIGHT ACROSS THE CWFA. MODELS
ARE SHOWING SIGNS OF AN MCS DEVELOPING IN THE NW FLOW AND AFFECTING
THE CWFA. STRONG SURFACE INSTABILITY AND VERY STEEP LAPSE RATES WILL
HELP SUSTAIN CONVECTION AND CONTINUE THE POSSIBILITY OF SEVERE
STORMS AT LEAST THROUGH MIDNIGHT.
FOR MONDAY...A 500MB TROUGH/SHEAR AXIS SETS UP RIGHT ALONG THE SE
COAST. THIS FEATURE SHOULD SERVE TO FOCUS ANY CONVECTIVE ACTIVITY
FOR MONDAY AND MONDAY EVENING. DO THINK SHRA/TSRA WILL BE MORE
DIURNAL IN NATURE. KEPT THE TREND OF HIGHEST POPS IN THE EAST...WITH
ONLY ISOLATED ACTIVITY TO THE WEST.
WEAK SHEAR AXIS/500MB TROUGH MOVES OFF THE COAST ON TUESDAY WITH
RIDGING BUILDING ALOFT ACROSS THE CWFA. ANY CONVECTION SHOULD BE
ISOLATED IN NATURE...SURFACE INSTABILITY WILL BE PRESENT BUT NO
DISCERNIBLE SURFACE MECHANISM TO FOCUS PRECIP IS NOTED. PRECIP
SHOULD BE DIURNAL.
UNCERTAINTY BEGINS TO CREEP INTO THE FORECAST BY WEDNESDAY. EARLIER
MODEL RUNS PROGGED A COLD FRONT TO MOVE THROUGH THE CWFA DURING THE
LATTER HALF OF THE WEEK. THE ECMWF NOW KEEPS THE FRONT TO THE
NORTH...WHILE THE GFS DOES MOVE THE BOUNDARY THROUGH SLOWLY FRIDAY
THROUGH SATURDAY. HAVE OPTED TO GO PERSISTENCE FOR THIS PERIOD DUE
TO LOW CONFIDENCE.
NLISTEMAA
&&
AVIATION...
06Z UPDATE...
SHOWERS AND A FEW EMBEDDED TSTORMS WORKING EAST OUT OF AL INTO GA
TONIGHT. TIME OF ARRIVAL ON MAIN CELLS FOR ATLANTA AREA SITES
BETWEEN 07Z AND 08Z BUT AM NOT CONFIDENT THEY WILL HOLD TOGETHER
AS AIRMASS IS A LITTLE MORE STABLE ACROSS GA. THIS IS EVIDENT IN THE
LARGER CELL WEST OF CSG WHICH HAS BEEN WEAKENING AS IT MOVES EAST.
DID INCLUDE TSRA IN A TEMPO GROUP AT ATL OVERNIGHT FOR SOME OF THE
STRONGER CELLS. HRRR AND HIGH RES MODELS CONTINUE TO SHOW THE EAST WEST
BANDING OF STORMS THROUGH MID MORNING BUT PRIMARILY OVER AL AND
EXTREME WESTERN GA. WILL NEED TO MONITOR THIS FOR ANY SLIGHT
EASTWARD EXTENSION AND THE NEED TO AMD WITH THUNDER.
OTHERWISE...BELIEVE CLOUD DEBRIS WILL HAMPER EARLY TS DEVELOPMENT
ON SAT BUT STILL THINK TSTORMS WILL DEVELOP IN THE AFTERNOON
PARTICULARLY ACROSS NORTH GA. MVFR CIGS AND VSBYS ARE POSSIBLE
OVERNIGHT PARTICULARLY IN SHOWERS MAINLY BETWEEN 08Z AND 12Z AND
WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT OUT OF THE SOUTHWEST
BUT INCREASING TO AROUND 10KTS AFTER 16Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS
30
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 80 63 79 65 / 60 60 60 60
ATLANTA 78 65 79 66 / 70 70 60 60
BLAIRSVILLE 73 60 76 60 / 70 70 70 70
CARTERSVILLE 78 63 79 65 / 70 70 60 50
COLUMBUS 83 67 85 67 / 50 50 40 50
GAINESVILLE 76 63 76 63 / 70 70 70 60
MACON 85 64 84 66 / 50 50 60 60
ROME 79 63 81 65 / 70 70 60 40
PEACHTREE CITY 79 64 79 65 / 60 60 60 60
VIDALIA 88 69 87 68 / 40 40 60 60
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...30
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
214 AM EDT SAT MAY 18 2013
.PREV DISCUSSION... /ISSUED 920 PM EDT FRI MAY 17 2013/
UPDATE...
RE-ADJUSTED POPS AND WEATHER GRIDS TO ACCOUNT FOR CURRENT TRENDS...
BETTER CONVECTION IS SHIFTING SOUTH ACROSS ALABAMA ALONG THE BETTER
THETA-E AXIS. PLENTY OF LIGHT TO MODERATE SHOWERS STILL MOVING INTO
WESTERN PORTIONS OF THE FORECAST AREA...AND CANNOT RULE OUT SOME
THUNDER THROUGH THE OVERNIGHT WITH THE UPPER LOW SPINNING IN THE
VICINITY. THE REMAINDER OF THE FORECAST LOOKS OK FOR NOW SO LITTLE OR
NO CHANGES MADE AT THIS TIME.
20
PREV DISCUSSION... /ISSUED 805 PM EDT FRI MAY 17 2013/
SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
SCATTERED TO BROKEN CLOUD COVER PREVAILED OVER NORTH AND CENTRAL GA
AT THIS TIME WITH A FEW LIGHT SHOWERS. THE UPPER LEVEL TROUGH OVER
THE MS RIVER VALLEY HAS ASSOCIATED SHORT WAVES ROTATING THROUGH
NORTH AL AND CENTRAL TN WITH NUMEROUS SHOWERS AND SCATTERED TSTMS.
MOST MODELS ARE IN AGREEMENT THE TROUGH WILL GRADUALLY MOVE EAST
THROUGH SATURDAY NIGHT. THE UPPER LEVEL DISTURBANCES WILL COMBINE
WITH ADEQUATE GULF MOISTURE...PWS AROUND 1.5 INCHES...TO SPREAD
NUMEROUS SHOWERS AND SCATTERED TSTMS OVER THE NORTH HALF OF GA. WILL
LEAN TOWARD THE NAM...HRRR AND LOCAL WRF MODEL SOLUTIONS WHICH
EXPECT THE SHOWERS AND A FEW TSTMS TO ENTER NORTHWEST GA TONIGHT AND
OVER MOST OF NORTH GA BY MIDNIGHT. THE TSTM POTENTIAL SHOULD
DIMINISH TO ISOLATED LATER TONIGHT AS THE RAIN COOLED AIR STABILIZES
THE AIRMASS OVER THE STATE. DIURNAL HEATING ON SATURDAY WILL TRIGGER
ADDITIONAL TSTMS IN THE AFTERNOON AND EVENING WITH MUCAPES IN THE
1500-2000 J/KG RANGE. A SLIGHT RISK OF SEVERE TSTMS WILL BE
POSSIBLE...MAINLY OVER NORTHWEST GA DUE TO THE CLOSE PROXIMITY OF
THE UPPER LEVEL TROUGH. QPF AMOUNTS OF 1 TO 1.5 INCHES ARE EXPECTED
OVER NORTH GA WITH 0.75 INCH OR LESS OVER CENTRAL GA. TEMPORARY
STREET FLOODING WILL BE POSSIBLE WITH PERIODS OF HEAVY
RAIN...HOWEVER CREEK OR RIVER FLOODING SHOULD BE LIMITED UNLESS MORE
QPF DEVELOPS IN A MUCH SHORTER PERIOD OF TIME. A MET/MAV MOS BLEND
WAS USED FOR MIN AND MAX TEMPS.
16
LONG TERM /SUNDAY THROUGH FRIDAY/...
SHORTWAVE IS IN THE PROCESS OF SHIFTING EAST OF THE CWA ON
SUNDAY...SO THIS...IN ADDITION TO PLENTY OF MOISTURE ACROSS THE
CWA AND FORECAST MUCAPE AROUND 3000 J/KG WILL ALLOW FOR THE TREND
OF SHOWERS AND THUNDERSTORMS TO CONTINUE INTO SUNDAY. HAVE
EXTENDED LIKELY POPS FURTHER WEST THAN PREVIOUS FORECAST FOR
SUNDAY. WITH UPPER RIDGE BUILDING IN FOR MONDAY AND
TUESDAY...POPS DECREASE...BUT THERE IS ENOUGH MOISTURE AROUND TO
KEEP SLIGHT CHANCE TO CHANCE POPS. GFS AND ECMWF STILL DIFFER
WITH MID-WEEK FRONTAL BOUNDARY WITH THE ECMWF FASTER THAN THE GFS
IN THE 12Z RUN. GIVEN DIFFERENCES...HAVE CONTINUED THE TRENDS
ADVERTISED IN THE PREVIOUS FORECAST. THE PREVIOUS DISCUSSION FOLLOWS.
11
LONG TERM /SATURDAY THROUGH THURSDAY/...
MODELS IN GENERAL AGREEMENT FOR SATURDAY TARGETING THE AREA WITH
SCATTERED TO NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. THIS
DUE TO THE INFLUENCE OF UPPER LOW PRESSURE MOVING TO THE OH/TN
VALLEY AREAS AND THE MAIN UPPER TROUGH AFFECTING GA. WHILE N GA IS
TARGETED WITH THE HIGHEST POPS...INSTABILITY ACROSS THE AREA WILL
ALLOW FOR SCATTERED SHOWERS/STORMS ACROSS CENTRAL GA AS WELL. EVEN
WITH CLOUDS AND PRECIP CHANCES...A WARM AIRMASS IN PLACE WILL
ALLOW FOR HIGH TEMPERATURES NEAR NORMAL.
UPPER SYSTEM IN THE PROCESS OF PASSING THE AREA FOR SUNDAY BUT STILL
PLENTY OF MOISTURE AND INSTABILITY IN PLACE FOR SCATTERED TO
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. MODELS IN SOME
DISAGREEMENT FOR MONDAY WITH THE GFS WETTER THAN THE EUROPEAN AS THE
EUROPEAN HAS A STRONGER DRIER UPPER RIDGE MOVING OVER THE AREA THAN
THE GFS. GFS CONTINUES TO BE WETTER ON TUESDAY THAN THE EUROPEAN
WITH THE INFLUENCE OF AN UPPER RIDGE OVER THE AREA. STILL PLENTY OF
MOISTURE AND INSTABILITY FOR SOME AFTERNOON/EVENING CONVECTION.
INFLUENCE OF THE UPPER RIDGE DIMINISHES ON WEDNESDAY AS A COLD FRONT
MOVES ACROSS THE MID U.S. THIS WILL ALLOW FOR THE CHANCES OF SHOWERS
AND STORMS ACROSS THE AREA WITH CHANCES A LITTLE HIGHER ACROSS THE
N. GFS/EUROPEAN IN DISAGREEMENT WITH THE FRONT ON THURSDAY WITH THE
GFS MOVING THE FRONT INTO THE AREA AND THE EUROPEAN KEEPING THE
FRONT WELL TO THE NW. MOISTURE AND INSTABILITY WILL AGAIN COMBINE
FOR A CHANCE OF SHOWERS AND STORMS. A WEAK FRONT WILL LIKELY BE IN
THE AREA ON FRIDAY WITH AT LEAST SMALL CHANCES FOR SHOWERS AND
STORMS. TEMPERATURES GENERALLY RUNNING NEAR TO ABOVE NORMAL.
BDL
AVIATION...
00Z UPDATE...
VFR CONDITIONS WILL PREDOMINATE ACROSS THE FORECAST AREA THROUGH THE
MAJORITY OF THIS FORECAST PERIOD...OUTSIDE OF AREAS OF CONVECTION.
THERE IS A CHANCE FOR SOME SCATTERED AREAS OF MVFR CEILINGS AND
VISIBILITIES BETWEEN 02Z AND 14Z...MAINLY IN AREAS THAT SEE BETTER
RAINFALL. BEST CHANCES FOR MAINLY SHOWERS TONIGHT AT THE TAF SITES
WILL BE BETWEEN 02Z AND 09Z AS A LARGE...WEAKENING...AREA OF
CONVECTION MOVES EAST OUT OF ALABAMA. ISOLATED THUNDERSTORMS ARE
POSSIBLE WITH THIS AREA. BETTER CHANCES FOR THUNDER WILL BE AFTER
16Z SATURDAY. WINDS WILL BE FAIRLY LIGHT AND VARIABLE THROUGH 14Z...
BUT WILL FAVOR SOUTHWEST TO SOUTHEAST. SOUTHWEST WINDS WILL INCREASE
TO 6-10KT AFTER 16Z.
//ATL CONFIDENCE...00Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS.
20
&&
.AVIATION...
06Z UPDATE...
SHOWERS AND A FEW EMBEDDED TSTORMS WORKING EAST OUT OF AL INTO GA
TONIGHT. TIME OF ARRIVAL ON MAIN CELLS FOR ATLANTA AREA SITES
BETWEEN 07Z AND 08Z BUT AM NOT CONFIDENT THEY WILL HOLD TOGETHER
AS AIRMASS IS A LITTLE MORE STABLE ACROSS GA. THIS IS EVIDENT IN THE
LARGER CELL WEST OF CSG WHICH HAS BEEN WEAKENING AS IT MOVES EAST.
DID INCLUDE TSRA IN A TEMPO GROUP AT ATL OVERNIGHT FOR SOME OF THE
STRONGER CELLS. HRRR AND HIGH RES MODELS CONTINUE TO SHOW THE EAST WEST
BANDING OF STORMS THROUGH MID MORNING BUT PRIMARILY OVER AL AND
EXTREME WESTERN GA. WILL NEED TO MONITOR THIS FOR ANY SLIGHT
EASTWARD EXTENSION AND THE NEED TO AMD WITH THUNDER.
OTHERWISE...BELIEVE CLOUD DEBRIS WILL HAMPER EARLY TS DEVELOPMENT
ON SAT BUT STILL THINK TSTORMS WILL DEVELOP IN THE AFTERNOON
PARTICULARLY ACROSS NORTH GA. MVFR CIGS AND VSBYS ARE POSSIBLE
OVERNIGHT PARTICULARLY IN SHOWERS MAINLY BETWEEN 08Z AND 12Z AND
WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT OUT OF THE SOUTHWEST
BUT INCREASING TO AROUND 10KTS AFTER 16Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS
30
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 82 64 82 66 / 60 60 60 40
ATLANTA 81 65 82 68 / 70 70 60 30
BLAIRSVILLE 73 57 78 60 / 70 70 70 50
CARTERSVILLE 80 64 82 66 / 70 70 60 20
COLUMBUS 85 67 86 67 / 50 50 30 20
GAINESVILLE 79 64 80 66 / 70 70 60 40
MACON 84 64 85 66 / 50 50 50 30
ROME 80 64 83 66 / 70 70 60 20
PEACHTREE CITY 80 63 84 64 / 60 60 50 20
VIDALIA 87 67 86 68 / 40 40 50 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...30
LONG TERM....NLISTEMAA
AVIATION...NLISTEMAA
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1024 PM CDT SUN MAY 19 2013
.MESOSCALE DISCUSSION...
1015 PM CDT
CLUSTER OF STORMS THAT PRODUCED SCATTERED DAMAGING WINDS FROM
NORTHWEST INTO NORTH CENTRAL IL HAS DISSIPATED QUICKLY AS THE LOW-
LEVELS HAVE STABILIZED AND THE BETTER MID-LEVEL FORCING TRANSLATES
MORE NORTHWARD THAN EASTWARD. OUTFLOW FROM THIS HAS ALSO LOST
STEAM. THIS WILL LIKELY MAKE IT TO THE LAKEFRONT IN LAKE AND
NORTHERN COOK COUNTIES...BUT WIND GUSTS WILL CONTINUE TO DIMINISH
WITH IT.
AS FOR THE ONGOING CONVECTION MOVING INTO EASTERN IA AND MO...THE
MOST ROBUST PORTIONS OF THIS ARE ALSO MOVING MORE N/NE THAN ENE.
STEERING FLOW AND PROPOGATION VECTORS FROM THE RAP WOULD INDICATE
THIS TO PRIMARILY CONTINUE. THE LOW-LEVEL JET NOSE WILL VEER
SLIGHTLY MORE NORTHEAST...SO REMNANT CONVECTIVE ACTIVITY/SHOWERS
WILL LIKELY APPROACH OR MAKE IT INTO THE NORTHWEST AND NORTHERN
FORECAST AREA AND POTENTIALLY ACROSS A LARGE PART OF IT DURING THE
POST DAYBREAK HOURS.
IN BETWEEN...FROM NOW THROUGH 3 AM...THERE IS A SMALL CHANCE FOR
CONVECTION TO DEVELOP WITHIN THE GRADUALLY INCREASING WARM AIR
ADVECTION/MOISTURE TRANSPORT...AND POTENTIALLY ON LINGERING
BOUNDARIES /MAINLY ELEVATED/. ANY CONVECTION ITSELF WOULD VERY
LIKELY BE ELEVATED...UNLESS ANYTHING WERE TO CONGEAL...SO TORNADO
THREAT HAS DIMINISHED CONSIDERABLY.
MTF
&&
.DISCUSSION...
308 PM...CONVECTIVE/PRECIP POTENTIAL REMAINS THE MAIN FORECAST
CONCERN/CHALLENGE...THROUGH MID WEEK.
THUNDERSTORMS THAT DEVELOPED ACROSS WESTERN IL LATE THIS MORNING
DISSIPATED AS THEY MOVED NORTHEAST INTO A VERY CAPPED ATMOSPHERE
WHILE THUNDERSTORMS THAT DEVELOPED A BIT FURTHER NORTH AND ARE NOW
MOVING ACROSS FAR SOUTHERN WI APPEAR TO BE ASSOCIATED WITH A WAVE
MOVING ACROSS IOWA. THIS ACTIVITY HAS ALSO STRUGGLED TO SHIFT EAST
DUE TO THE CAPPED ENVIRONMENT. THIS WAVE LIFTS NORTH THIS EVENING
AND IT APPEARS ANY ADDITIONAL THUNDERSTORMS WILL SPREAD ACROSS THE
AREA LATER THIS EVENING AND MORE LIKELY OVERNIGHT FROM CONVECTION
FIRING ACROSS THE PLAINS. SHORT TERM GUIDANCE CONTINUES TO SUGGEST
ADDITIONAL DEVELOPMENT ACROSS NORTHERN MISSOURI LATE THIS
AFTERNOON WHICH WOULD ARRIVE IN THE WESTERN CWA BY SUNSET BUT ITS
DIFFICULT TO SEE WHAT WAVE WOULD HELP KICK OFF THIS ACTIVITY BUT
HAVE MAINTAINED LOW CHANCE POPS THROUGH MID EVENING ACROSS THE
WESTERN CWA.
WITH THE EXPECTATION THAT OVERNIGHT CONVECTION WILL BE SPREADING
NORTHEAST AND DISSIPATING MONDAY MORNING...THIS SHOULD ALLOW FOR A
PERIOD OF DRY CONDITIONS INTO EARLY MONDAY AFTERNOON. CAP MONDAY
AFTERNOON IS MUCH WEAKER THAN TODAY AND EVEN APPEARS TO BE GONE
ACROSS WESTERN AREAS BY MID/LATE AFTERNOON. LITTLE CHANGE TO THE
AIRMASS OVER THE NEXT 24 HRS...PERHAPS DEWPOINTS SLIGHTLY HIGHER
THUS WHILE THUNDERSTORM COVERAGE/TIMING REMAINS UNCERTAIN...
ANYTHING THAT DEVELOPS WILL HAVE THE POTENTIAL TO BECOME SEVERE
WITH DAMAGING WINDS THE MAIN THREAT AND LARGE HAIL THE SECONDARY
THREAT.
FROM MONDAY NIGHT THROUGH WEDNESDAY MORNING...THERE AGAIN APPEARS
TO BE SOME CONSENSUS...ESPECIALLY WITH THE ECMWF/GEM FOR A SERIES
OF WAVES TO MOVE ACROSS THE WESTERN/SOUTHERN LAKES REGION AS THE
UPPER LOW SLOWLY SHIFTS EAST THROUGH MIDWEEK AND EVENTUALLY OPENS
INTO A TROUGH WITH A PERIOD OF THUNDERSTORMS/HEAVY RAIN MONDAY
NIGHT INTO TUESDAY MORNING AND THE AGAIN TUESDAY NIGHT INTO
WEDNESDAY MORNING. WITH PRECIPITABLE WATER VALUES APPROACHING 1.5
INCHES AND PLENTY OF LEVEL MOISTURE...LOCALLY HEAVY...PERHAPS EVEN
TORRENTIAL RAINFALL WILL BE POSSIBLE. STORM TOTAL MODEL QPF
AMOUNTS ARE STILL SOMEWHAT LOW RANGING IN THE 1 TO 2 INCHES BUT
SHOULD CONVECTION TRAIN OVER THE SAME AREAS...LOCALLY HIGHER
AMOUNTS ARE CERTAINLY POSSIBLE. THE MAIN SURFACE LOW MOVES EAST
ACROSS THE SOUTHERN LAKES WEDNESDAY INTO WEDNESDAY NIGHT WITH A
TRAILING COLD FRONT PUSHING SOUTH ACROSS THE AREA. THIS WILL USHER
IN MUCH COOLER AND DRIER CONDITIONS FOR END OF THE WEEK.
HIGHS TODAY HAVE REACHED IN THE MID/UPPER 80S MOST LOCATIONS WITH
SEVERAL LOCATIONS TAGGING 90 ACROSS THE WESTERN CWA. DEPENDING ON
CLOUDS AND CONVECTIVE TRENDS...UPPER 80S/LOWER 90S LOOK REASONABLE
AGAIN FOR MONDAY. SOUTHERLY WINDS SHOULD BE STRONG ENOUGH TO
PREVENT ANY LAKE COOLING BUT OUTFLOW FROM ANY THUNDERSTORMS COULD
TURN WINDS ONSHORE WITH MUCH COOLER TEMPERATURES. HIGHS ON TUESDAY
STILL POTENTIALLY INTO THE 80S BUT AGAIN DEPENDENT ON CLOUD COVER/
PRECIP TRENDS. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* CONVECTIVE OUTFLOW SHIFTING WINDS TO THE WEST AT LEAST NEARING
ORD.
* CHANCE OF TSRA LATE TONIGHT AND THROUGH ALL OF MONDAY...WITH THE
MOST FAVORED TIMES HIGHLIGHTED IN THE TAFS.
* GUSTY SOUTH WINDS THROUGH MONDAY.
//DISCUSSION...UPDATED 00Z...
A COMPLEX AVIATION FORECAST WITH CHANCES OF THUNDERSTORMS FOR MUCH
OF MONDAY AND TUESDAY. INITIALLY...A LAKE BREEZE WHICH DEVELOPED
EARLIER HAD RETREATED DUE TO A WARM FRONT INFLUENCE...BUT NOW HAS
PUSHED BACK. PER COORDINATION WITH ORD TOWER THIS IS BASICALLY
SITTING OVER THE AIRFIELD AND SHOULD THROUGH 01Z OR SO. WIND GUSTS
AT TIMES WILL BE BETWEEN 10 TO 15 KT WITH SPEEDS FLUCTUATING
BETWEEN 100 AND 170 DEGREES. THIS FEATURE SHOULD REMAIN JUST EAST
OF MDW. THE ONLY OTHER WIND NOTE FOR TONIGHT IS THAT ALOFT A LOW-
LEVEL JET WILL ORIENT ITSELF OVER THE AREA WITH SW WINDS OF 35-40
KT ABOVE 1500 FT. THIS DOES NOT LOOK TO PRESENT TRUE LLWS...BUT
MAY BE CLOSE...NAMELY AT RFD.
AS FOR CONVECTION...ONGOING STORMS IN WESTERN IL HAVE A FAVORABLE
ENVIRONMENT AND RADAR TRENDS TO EVOLVE NORTHEAST INTO PART OF THE
FAR WESTERN TRACON AREA AND NEAR RFD. SOME OF THESE COULD HAVE
SOME GUSTY WINDS NEAR RFD. THE BETTER CHANCE FOR STORMS AT
CHICAGOLAND TAF SITES ARRIVES ON MONDAY AND MONDAY
NIGHT...ALTHOUGH IT IS TOUGH TO TIME THE BEST WINDOW. IT IS
EXPECTED THAT THE NUMEROUS STORM COMPLEXS OVER THE PLAINS/MO/IA
WILL FADE LATE TONIGHT INTO THE MORNING AS THEY HAD EAST...BUT THE
REMNANTS COULD BRING SCT SHRA/TSRA TO THE AREA IN THE MORNING.
MONDAY WILL PRESENT LESS OF A CAP IN THE ATMOSPHERE SO AT LEAST
SCATTERED CONVECTION WILL PROBABLY BE SEEN IN NORTHERN IL BY LATE
AFTERNOON/EVE.
WITH A TIGHTER PRESSURE GRADIENT AND CONTINUED PRESSURE FALLS
ACROSS THE AREA ON MONDAY...SOUTHERLY WINDS SHOULD SEE GUSTS TO
THE 25 KT BALLPARK DURING THE LATE MORNING AND AFTERNOON ACROSS
ALL TAF SITES.
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* LOW CONFIDENCE ON OUTFLOW REACHING ORD.
* MEDIUM CONFIDENCE ON MORNING SHRA CHANCES.
* MEDIUM CONFIDENCE IN AT LEAST HAVING CONVECTION IN THE REGION ON
MONDAY AFTERNOON AND EVE BUT LOW CONFIDENCE ON SPECIFIC TIMING.
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY...PERIODS OF TSRA. GUSTY SW WINDS.
WEDNESDAY...LIKELY TSRA DURING THE DAY. CHC DURING THE NIGHT.
POTENTIAL FOR MVFR CIGS.
THURSDAY...CHANCE OF SHRA.
FRIDAY...VFR LIKELY. GUSTY NE WINDS.
SATURDAY...CHC OF TSRA DURING THE NIGHT.
MTF
&&
.MARINE...
159 PM CDT
THE MAIN WEATHER MAKER FOR THE NEXT FEW DAYS WILL BE THE SURFACE
LOW...CURRENTLY ACROSS THE PLAINS. THIS STORM SYSTEM IS EXPECTED TO
MOVE EAST-NORTHEASTWARD TOWARDS THE MID MISSOURI VALLEY TONIGHT INTO
MONDAY MORNING. AS IT DOES SO...AN ASSOCIATED SURFACE WARM
FRONT...EXTENDING EASTWARD ACROSS NORTHERN ILLINOIS AND
INDIANA...WILL MOVE NORTHWARD ACROSS AT THE SOUTHERN HALF TO TWO
THIRDS OF THE LAKE LATER TONIGHT AND ON MONDAY. IN THE WAKE OF THIS
FRONT...THE WINDS WILL SHIFT MORE SOUTHERLY AND SHOULD INCREASE UP
TO 15 TO 25 KT BY MONDAY. HOWEVER...TO THE NORTH OF THIS
FRONT...WINDS WILL PRIMARILY REMAIN EASTERLY AT AROUND THE SAME
MAGNITUDE.
THE OTHER CONCERN WILL BE THE THREAT FOR PERIODS OF DENSE MARINE FOG
LATER TONIGHT AND INTO AT LEAST THE FIRST PART OF THE WEEK. AS
THIS WARM FRONT LIFTS OVER THE LAKE...MUCH HIGHER DEW POINTS WILL
MOVE OVER THE RELATIVELY COLD WATER...POSSIBLY RESULTING IN SOME FOG
DEVELOPMENT.
IT APPEARS THAT THE SURFACE LOW WILL SLOWLY MOVE EASTWARD ACROSS THE
MID MISSISSIPPI VALLEY AND TO NEAR SOUTHERN LAKE MICHIGAN BY MID
WEEK AND THEN CONTINUE EASTWARD ACROSS THE LOWER GREAT LAKES REGION
LATER IN THE WEEK. THIS SHOULD ALLOW WARM FRONT TO SHIFT BACK
SOUTHWARD WITH TIME DURING THE WEEK. DURING THIS TIME...THE WIND
DIRECTIONS WILL PRIMARILY BECOME EAST NORTHEASTWARD 15 TO 25 KT
NORTH OF THE FRONT. LATER IN THE WEEK...AS THE SURFACE
LOW PASSES EAST OF LAKE MICHIGAN...THE WINDS STILL LOOK TO BE RATHER
STOUT UP TO 30 KT OUT OF THE NORTH FOR A PERIOD AS A GOOD AREA OF
HIGH PRESSURE BUILDS EASTWARD ACROSS ONTARIO AND THE UPPER GREAT
LAKES REGION.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS LINCOLN IL
1137 PM CDT FRI MAY 17 2013
.DISCUSSION...
ISSUED 830 PM CDT FRI MAY 17 2013
01Z/8PM RADAR IMAGERY SHOWS ISOLATED SHOWERS ALONG/NORTHWEST OF A
PETERSBURG TO BLOOMINGTON-NORMAL LINE. THESE SHOWERS WILL CONTINUE
TO DRIFT SLOWLY NORTHWARD BEFORE DISSIPATING BY AROUND 10PM. AFTER
THAT...DRY WEATHER IS ANTICIPATED OVERNIGHT. WITH MOIST DEWPOINTS
IN THE LOWER TO MIDDLE 60S AND VERY LIGHT WINDS...EXPECT FOG TO
DEVELOP AFTER MIDNIGHT. HRRR SUGGESTS VISBYS MAY DROP TO 1SM OR
LESS TOWARD DAWN...HOWEVER THINK THIS MAY BE A BIT TOO AGGRESSIVE
GIVEN THE AMOUNT OF CLOUD COVER THAT SHOULD BE STICKING AROUND. AT
THIS POINT...WILL JUST CARRY PATCHY FOG OVERNIGHT. ZONE UPDATE HAS
ALREADY BEEN ISSUED.
&&
.AVIATION...
ISSUED 1137 PM CDT FRI MAY 17 2013
PERSISTENT CLUSTER OF SHOWERS NEAR KPIA WILL GRADUALLY DISSIPATE
BY 06Z...HOWEVER WILL MAINTAIN VCSH THROUGH 08Z IN CASE A FEW
SHOWERS LINGER. WITH LIGHT WINDS AND PLENTY OF LOW-LEVEL MOISTURE IN
PLACE...PARTIAL CLEARING OVERNIGHT WILL LEAD TO THE DEVELOPMENT OF
PATCHY FOG. BIG QUESTION WILL BE WHETHER OR NOT A LOW OVERCAST
WILL FORM AS WELL. NAM FORECAST SOUNDINGS ARE SUGGESTING CEILINGS
OF AROUND 1000FT OVERNIGHT INTO EARLY SATURDAY MORNING. THINK THIS
IS OVERDONE AND WILL ONLY INCLUDE SCT CLOUD COVER AROUND 1500FT
ALONG WITH 2-4SM FOG OVERNIGHT. ONCE THE MORNING FOG/CLOUDS
LIFT...NEGATIVE CU-RULE POINTS TO A PARTLY SUNNY DAY WITH CLOUD
BASES AROUND 5000FT. WILL INCLUDE VCSH AT KCMI IN CLOSER PROXIMITY
TO UPPER LOW SPINNING OVER THE OHIO RIVER VALLEY. WINDS WILL BE
E/SE AT 10KT OR LESS THROUGH THE ENTIRE 06Z TAF PERIOD.
BARNES
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT FRI MAY 17 2013
AN EXTENDED PERIOD OF RAIN CHANCES WILL CONTINUE INTO THE WEEKEND
AND MOST OF NEXT WEEK. THE MAIN WEATHER FEATURES WILL BE A
STATIONARY FRONT AND UPPER LOW THE REST OF TODAY AND
SATURDAY...THEN A WARM FRONT ACROSS IL AND DEEPENING LOW PRESSURE
IN THE PLAINS ON SUNDAY AND MONDAY...THEN A SLOW MOVING OCCLUDED
LOW MONDAY NIGHT THROUGH TUESDAY NIGHT...BEFORE A COLD FRONT
FINALLY PUSHES ACROSS ILLINOIS ON WEDNESDAY.
THE BEST WINDOW OF OPPORTUNITY FOR ANY LONGER BREAKS IN THE RAIN
MAY BE SATURDAY AND SUNDAY...BUT STRONG INSTABILITY AS THE CAP
ERODES LATE SUNDAY AFTERNOON INTO SUNDAY EVENING MAY ALLOW FOR
STRONG TO SEVERE STORMS SUNDAY NIGHT NORTHWEST OF THE IL RIVER.
SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.
SHOWERS AND THUNDERSTORMS ERUPTED THIS AFTERNOON AS THE CAP
DISSIPATED...BUT COVERAGE WAS ISOLATED FOR THE MOST PART. THE
PRIMARY AREA OF ACTIVITY IN OUR AREA WAS FROM GALESBURG TO
HOOPESTON...CLOSER TO THE STATIONARY FRONT THAT EXTENDED ACROSS
NORTHERN IL. ADDITIONAL SHOWERS DEVELOPED FARTHER SOUTH FROM
JACKSONVILLE TO LAWRENCEVILLE ASSOCIATED WITH THE UPPER LOW MOVING
EAST INTO KENTUCKY. THE FRONT AND LOW WILL CONTINUE TO TRIGGER
SHOWERS AND STORMS INTO THE EVENING...BUT PROGRESSIVELY EAST WITH
TIME. BY MIDNIGHT...WE EXPECT PRECIP TO COME TO AN END IN CENTRAL
IL.
MOST OF THE DAY ON SATURDAY SHOULD BE DRY...BUT WE CAN NOT RULE
OUT SOME DIURNAL SHOWERS AND ISOLATED STORMS EAST OF I-57 AS THE
UPPER LOW LINGERS NEARBY TO THE EAST OF IL. A LULL IN THE RAIN
LOOKS LIKELY SATURDAY NIGHT AND MUCH OF SUNDAY...AS WARM AIR
SURGES INTO THE AREA. DEWPOINTS ON SUNDAY WILL CLIMB INTO THE
LOWER 70S AS HIGH TEMPS REACH THE UPPER 80S. A LOW LEVEL INVERSION
WILL PROVIDE A CAP UNTIL LATE IN THE DAY ON SUNDAY. ELEVATED
INSTABILITY WILL INCREASE DRAMATICALLY BY LATE AFTERNOON...WITH ML
CAPE VALUES AROUND 4K J/KG AND LI`S OF -10C. THE CAP WILL ERODE
FROM WEST TO EAST...REACHING PEORIA TO SPI BY 6-7 PM. SO OUR
WESTERN COUNTIES WILL HAVE THE BEST CHANCES FOR STRONG TO SEVERE
STORMS SUNDAY EVENING. TONED DOWN STORMS ARE EXPECTED TO ADVANCE
EAST TOWARD I-57 AFTER MIDNIGHT SUNDAY NIGHT.
MONDAY LOOKS TO BE LESS LIKELY FOR STORMS THAN PREVIOUS FORECAST
MODEL SOLUTIONS INDICATED. CLOUD COVER WILL KEEP HIGH TEMPS IN THE
LOWER 80S...BUT WE WILL REMAIN IN THE WARM SECTOR. WE REMOVED ANY
LIKELY POPS FROM MONDAY AND KEPT CHANCE POPS ACROSS THE AREA.
INSTABILITY PARAMS BECOME FAVORABLE AGAIN FOR STRONG STORMS MONDAY
EVENING...AS WE BREAK THE INVERSION AGAIN...BUT WE ARE NOT IN THE
SPC DAY 4 OUTLOOK FOR MON-MON NIGHT LIKE WE WERE IN THE DAY 5
OUTLOOK YESTERDAY. LACK OF A SOLID FOCUSING MECHANISM IS ONE OF
THE REASONS WHY. THE WARM FRONT WILL BE NORTH OF OUR AREA...AND
THE OCCLUDED LOW AND ITS ENERGY WILL BE MAINLY IN THE NORTHERN
PLAINS.
LONG TERM...TUESDAY THROUGH FRIDAY.
AS THE OCCLUDED LOW MOVES TOWARD IL ON TUESDAY...AND SETTLES OVER
N-NW IL TUESDAY NIGHT COVERAGE OF SHOWERS AND STORMS WILL BECOME
MORE WIDESPREAD. LIKELY POPS WERE INCLUDED EVERYWHERE BUT THE FAR
WESTERN COUNTIES TUESDAY AND TUESDAY NIGHT...WITH LOCALLY HEAVY
RAINFALL POSSIBLE AS STORM MOTIONS REMAIN SLOW.
THE COLD FRONT WILL EVENTUALLY MOVE ACROSS OUR AREA ON WEDNESDAY
AS THE LOW PRESSURE SYSTEM FINALLY PULLS AWAY TO THE NORTHEAST.
DRIER CONDITIONS WILL BEGIN TO RETURN WED NIGHT...BUT THE COLD
POOL ALOFT WILL KEEP CHANCES OF INSTABILITY SHOWERS IN PLACE FOR
THURSDAY.
THE COLDEST AIR OF THE WEEK WILL COME THURSDAY THROUGH FRIDAY...AS
HIGHS ONLY REACH THE LOW TO MID 70S...AND LOWS DIP INTO THE 50S.
SUNSHINE AND DRY CONDITIONS RETURN FOR FRIDAY...FINALLY.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
826 PM EDT SUN MAY 19 2013
.SYNOPSIS...
ISSUED AT 504 PM EDT SUN MAY 19 2013
SKIES WILL REMAIN MOSTLY CLEAR TO PARTLY CLOUDY TONIGHT...WITH LOW
TEMPERATURES MAINLY IN THE MID 60S. A LOW PRESSURE SYSTEM WILL MAKE
ITS WAY ACROSS THE REGION EARLY THIS WEEK...BRINGING CHANCES FOR
SHOWERS AND THUNDERSTORMS THROUGHOUT THE WEEK. TEMPERATURES ARE
EXPECTED TO BE FAIRLY WARM MONDAY AND TUESDAY BEFORE DROPPING DOWN
TO MORE SEASONABLE LEVELS BY THE END OF THE WEEK.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013
TIGHT DEWPOINT GRADIENT WHICH HAD BEEN EVER PERSISTENT ACROSS OUR
AREA HAS FINALLY BEEN ERRADICATED AS LOW TO MID 60S DEWPOINTS HAVE
NOW OVERSPREAD THE ENTIRE CWA. THIS INCREASE IN SURFACE DEWPOINTS
HAS YIELDED SBCAPE VALUES BETWEEN 1500 AND 2000 J/KG. WITH A LACK OF
ANY SIGNIFICANT FORCING...NOTHING MORE THAN A SCATTERED TO BROKEN CU
DECK HAS BEEN ABLE TO DEVELOP. THIS CU FIELD WILL DISSIPATE BY
LATE AFTERNOON AS A DEEP EML/CAPPING INVERSION OVERSPREADS THE CWA
FROM THE WEST.
PRECIP POTENTIAL FOR TONIGHT REMAINS COMPLICATED AS SIGNIFICANT
MODEL SPREAD EXISTS REGARDING THE LOCATION AND PERSISTENCE OF
REMNANT CONVECTION FROM IOWA/MISSOURI SEVERE WEATHER TODAY. GLOBAL
MODELS KEEP CONVECTION NORTHWEST OF OUR CWA...WHILE HI
RESOLUTION/CONVECTION ALLOWING MODELS BRING PRECIP INTO AT LEAST THE
WESTERN HALF OF THE CWA AFTER 05Z BEFORE COMPLETELY DISSIPATING.
KEPT SLIGHT CHANCE POPS IN THE NORTHWEST OVERNIGHT WITH THE ONLY
CHANGE BEING A SLIGHTLY EARLIER ARRIVAL TIME AS HRRR GUIDANCE IS
CONSISTENTLY BRINGING CONVECTION INTO WESTERN AREAS BETWEEN 03-04Z.
TEMPS WILL WARM INTO THE UPPER 80S ON MONDAY WITH A FEW LOCATIONS
LIKELY REACHING 90 DEGREES. THESE ABOVE NORMAL TEMPS COUPLED WITH
UPPER 60S TO NEAR 70 DEWPOINTS WILL MAKE THE MONDAY AIRMASS QUITE
UNSTABLE. KEPT POPS IN THE LOW CHANCE RANGE AS UNCERTAINTIES
REGARDING THE STRENGTH OF THE CAP AND ANY CONVECTIVE DEBRIS WHICH
MAY OVERSPREAD THE AREA LIMIT CONFIDENCE. IF CONVECTION CAN
DEVELOP...SEVERE POTENTIAL WILL INCREASE THROUGH TIME AS A 50-60 KT
MID-LEVEL JET STREAK CLIPS THE NORTHWEST PORTION OF OUR FORECAST
AREA NEAR 21Z AND IMPROVES THE SHEAR PROFILE.
&&
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 320 PM EDT SUN MAY 19 2013
FCST PERIOD TO BEGIN WITH SFC LOW AND VERTICALLY STACKED CLOSED
UPPER LOW OVER THE NORTHERN PLAINS/UPPER MIDWEST. BEST FOCUS AND
FORCING FOR CONVECTIVE INITIATION HEADING INTO MONDAY EVENING WILL
BE TO THE WEST OF OUR AREA DESPITE BEING IN A VERY UNSTABLE WARM
SECTOR WITH CAPES AOA 3000J/KG OVER MUCH OF THE CWA. 500MB RIDGE
SHIFTS EAST OF THE AREA MON NITE AND BREAKDOWN OF THICKNESS RIDGE
WILL PROVIDE AN OPPORTUNITY FOR CONVECTION TO WORK INTO THE WESTERN
CWA 06-12Z TUE. GOOD MOISTURE ADVECTION ON A 40-50KT LLJ ALONG WITH
A 50-60KT MID LEVEL SPEED MAX WILL ACCOMPANY SFC PRE-FRONTAL TROF ON
TUE BRINGING GOOD CONVECTIVE POTENTIAL INTO THE AREA. UNCERTAINTY
WILL BE IN ABILITY FOR DESTABILIZATION...PUTTING SEVERE POTENTIAL IN
QUESTION. MAIN SFC FRONT TO FOLLOW ON WED WHICH WILL KEEP LIKELY
POPS FOR SH/TSRA GOING DURING THE DAY. SECONDARY FRONT THEN SET TO
MOVE THRU ON THURSDAY BEFORE ENTIRE SYSTEM FINALLY KICKS EAST OF OUR
AREA AND SETS THE STAGE FOR A COOLER BUT PLEASANT START TO THE
MEMORIAL DAY WEEKEND AS CANADIAN HIGH PRESSURE BUILDS INTO THE GREAT
LAKES REGION ON FRI/SAT. GFS AND ECMWF TRENDING TOWARD A MUCH
DIFFERENT SOLN COMPARED TO EARLIER RUNS FOR THE REST OF THE HOLIDAY
WEEKEND. WHAT WAS ONCE AN AMPLIFIED NW FLOW PATTERN WITH A
RE-ENFORCING DRY CANADIAN AIRMASS IS NOW BEING OFFERED AS A
TRANSITION TO A MORE ZONAL PATTERN AND KICKING SHORTWAVE DISTURBANCE
INTO THE REGION AND A CHANCE FOR PRECIP SUNDAY. NOT EAGER TO BUY
INTO THIS SOLN JUST YET...ESPECIALLY GIVEN THAT EVEN THE HIGHER END
OF THE ENSEMBLE MEMBERS HAVE POPS BELOW CLIMO. THAT AND GIVEN ITS IN
DAY 7 WILL OPT TO CONTINUE WITH DRY FCST FOR NOW AND WAIT TO SEE IF
TREND CONTINUES AND STRONGER SIGNAL IN MODEL GUIDANCE PRESENTS
ITSELF.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 825 PM EDT SUN MAY 19 2013
VFR MET CONDITIONS CONTINUE ODDS ON FAVORITE THROUGH THE FORECAST
PERIOD. INTENSE CONVECTIVE UPSTREAM TIED TO PLAINS DRYLINE/PVU
ANOMALY PUNCHING THROUGH EASTERN KS. WITH NORTHERN INDIANA WELL
REMOVED FROM BELT OF STRONGEST SOUTHWESTERLIES AND SECURELY CAPPED
AT THIS TIME...THE PRIME FOCUS AREA FOR COLLOCATED INSTABILITY AND
FORCED ASCENT WILL REMAIN WELL SOUTHWEST-WEST-NORTHWEST OF
NORTHERN INDIANA TERMINAL SITES. A GRADUAL UPTICK IN CONDITIONAL
PROBABILITIES FOR TSRA SEEN LATE IN FORECAST PERIOD...ESPECIALLY
INTO NORTHWEST INDIANA/KSBN VCNTY AS UPPER LOW COALESCES ACROSS
ND/SD/MN BORDER REGION BY 00 UTC TUE. STILL...CONVECTION MORE
LIKELY THAN NOT TO REMAIN UPSTREAM. WITH INITIATION FOCUSED ALONG
WARM FRONT EXTENSION ACROSS WISCONSIN...AND A SECONDARY AREA WELL
TO THE SOUTHWEST...WITHIN MAXIMUM LATE AFTERNOON DESTABILIZATION
ACROSS WEST CENTRAL ILLINOIS SOUTHWEST INTO OZARKS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...KG
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION...MURPHY
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS TOPEKA KS
354 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 315 AM CDT SAT MAY 18 2013
SHORT WAVE RIDGING IS RATHER EVIDENT ON THE 08Z WATER VAPOR IMAGERY
CENTERED OVER THE SOUTHERN AND CENTRAL PLAINS WITH THE RIDGE AXIS
LOCATED ROUGHLY OVER CENTRAL AND EASTERN KANSAS. SURFACE
OBSERVATIONS AT MICROWAVE IMAGERY SHOWS A DECENT STRATUS LAYER
ACROSS CENTRAL AND SOUTHERN KANSAS. EXPECT THIS AREA OF STRATUS TO
MOVE NORTH AND OVER THE FAR WESTERN ZONES THROUGH THE MORNING HOURS
BEFORE EVENTUALLY CLEARING OUT LATER TODAY. WITH THE RIDGE OVERHEAD
AND STRONG LOW/MID LEVEL CAPPING EXPECT A CUMULUS FIELD TO FORM WITH
DIURNAL HEATING...BUT STORMS ARE EXCEEDINGLY UNLIKELY TO FORM DUE TO
THE VERY WARM 700-800 MB TEMPERATURES. EXPECT RATHER WARM
TEMPERATURES TODAY...AS STRONG SUBSIDENCE WILL BE ONGOING DUE TO THE
RIDGE IN PLACE...AS WELL AS MIXING TO AROUND 850 MB. AS A RESULT THE
DAYTIME HIGHS WILL LIKELY REACH THE MIDDLE TO UPPER 80S TODAY.
FURTHER TO THE WEST A WELL PRONOUNCED DRY LINE WILL FORM IN SW/SC
KANSAS AND WILL LIKELY BE THE FOCUS FOR AFTERNOON THUNDERSTORMS ON
SATURDAY AFTERNOON. THESE STORMS WILL BE WELL WEST OF THE FORECAST
AREA IN THEIR STRONGEST FORM...BUT THEY WILL LIKELY ADVECT NORTH AND
EAST THROUGH THE EVENING AND OVERNIGHT HOURS...PERHAPS FORMING AN
OVERNIGHT MCS WHICH WOULD SLIDE EAST-NORTHEAST THROUGH THE FORECAST
AREA SATURDAY NIGHT INTO SUNDAY MORNING. WITH THE AFOREMENTIONED CAP
SOLIDLY IN PLACE ANY STORMS MOVING INTO NORTH CENTRAL AND NORTHEAST
KANSAS WILL HAVE A FORMIDABLE CHALLENGE TO OVERCOME ESPECIALLY THE
FURTHER EAST YOU GO...BUT IT WILL BE POSSIBLE FOR THE
WESTERN/CENTRAL KANSAS CONVECTION TO LEAK INTO THE AREA THIS EVENING
AND OVERNIGHT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 315 AM CDT SAT MAY 18 2013
SUNDAY...SEVERAL MODELS STILL SHOWING CONVECTION THAT DEVELOPS
OVER CENTRAL AND SW KANSAS MOVING NORTHEASTWARD INTO THE FORECAST
AREA THROUGH THE EARLY MORNING HOURS. WITH A CAP IN PLACE OVER
MUCH OF THE FORECAST AREA AM NOT HIGHLY CONFIDENT THAT A
THUNDERSTORM CLUSTER WILL BE ABLE TO ERODE THE CAP ON ITS OWN
ENOUGH FOR LASTING OVERNIGHT STORMS. THIS WILL HAVE SOME IMPACT
ON THE SEVERE WEATHER CHANCES FOR SUNDAY AFTERNOON...ALTHOUGH JUST
ABOUT ALL COMPUTER DEPICTIONS LIFT PRECIP OFF TO THE NORTH AS THE
CAP ALOFT REDEVELOPS IN THE AFTERNOON. COULD ALSO SEE SOME
ISOLD/SCT STORMS NORTH NEAR THE NEBRASKA BORDER ON THE EDGE OF THE
STRONGER CAPPING INVERSION.
SUNDAY AFTERNOON AND EVENING ARE STILL SHAPING UP TO BRING THE
CHANCE FOR SIGNIFICANT SEVERE WEATHER TO THE REGION. BY 18Z THE
UPPER TROF IS APPROACHING EASTERN KS WITH A NEGATIVE
TILT...SURFACE LOW HAS SHIFTED TO CENTRAL KANSAS AND INSTABILITY
INCREASES INTO 2500-3500J/KG...WITH THE NAM AS HIGH AS 4500 OUT
WEST OF MANHATTAN. 0-6KM BULK SHEAR RISES FROM 35KTS TO NEAR 50KTS
AROUND 0Z IN THE EASTERN COUNTIES...WITH THE GFS SHOWING 35KTS
FROM 0-1KM. LAPSE RATES ALOFT ARE 9C OR GREATER FOR A GOOD PORTION
OF THE SOUNDING...WITH AN UPPER JET MOVING PERPENDICULAR ACROSS
THE SURFACE TROF ALONG THE KS/OK BORDER THROUGH THE EVENING HOURS.
WITH SUCH STRONG INSTABILITY AND LAPSE RATES...AND GIVEN LACK OF
STRONG TURNING WITH HEIGHT IN THE WIND PROFILE...INITIAL THINKING
IS THAT LARGE HAIL...BASEBALL SIZE OR LARGER...IS A POSSIBILITY
WHERE STORMS CAN FORM LATER SUNDAY AFTERNOON. CANNOT RULE OUT
ISOLATED TORNADOES GIVEN STRONG INSTABILITY AND AVAILABLE SHEAR IN
THE COLUMN...AND WILL ALSO NEED TO KEEP WIND THREAT IN MIND FROM
NOT ONLY STRONG DISCRETE CELLS BUT ALSO POTENTIAL FOR LINE OF
STORMS TO FORM AND MOVE EASTWARD. MUCH OF THE EAST AND SOUTHEAST
PORTIONS OF OUR FORECAST AREA HAVE BEEN PUT IN A MODERATE DAY 2
RISK FOR THIS POTENTIAL. CHANCES FOR OVERNIGHT ACTIVITY MAY ALSO
HAVE AN INFLUENCE ON TIMING AND ONSET OF SEVERE WEATHER ON SUNDAY.
AT THIS TIME THINK BEST CHANCES ARE IN THE AFTERNOON INTO THE
EVENING HOURS...WITH LARGE HAIL...WIND GUSTS AND ISOLATED
TORNADOES A POSSIBILITY...WITH THE GREATER THREAT IN AREAS EAST OF
ABILENE. 67
FOR SUNDAY NIGHT...EC WANTS TO MOVE THE SECONDARY MAIN LOW OVER THE
AREA GOING INTO TUESDAY MORNING WHICH MAY TRIGGER YET ANOTHER LINE
OF SHOWERS AND STORMS FOR THE CENTRAL DN SC PARTS OF THE STATE. KEPT
HIGHER POPS ACROSS THE SE FOR POSSIBLY BOUNDARY HANGING UP OVER
THAT AREA.
TUESDAY AND WEDNESDAY UPPER LOW CONTINUES TO SLOWLY SIT AND SPIN
OVER THE NORTHERN PLAINS THROUGH THURSDAY BEFORE IT STARTS TO
SHIFT EASTWARD. COOLER THAN NORMAL TEMPERATURES MAKE A BRIEF
RETURN THROUGH FRIDAY AS COOLER HIGH PRESSURE SETTLES SOUTHWARD
FROM THE NORTHERN PLAINS. 67
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM CDT FRI MAY 17 2013
CONFIDENCE IN IFR VSBY IS IS DIMINISHING AS OBJECTIVE GUIDANCE HAS
COME IN AND BACKED OFF ON VSBY RESTRICTIONS AND WINDS HAVE NOT
BEEN AS LIGHT AS EXPECTED. STILL THINK THERE WILL BE ENOUGH
RADIATIONAL COOLING FOR SOME MVFR VSBY TO OCCUR...BUT WILL REMOVE
THE MENTION OF IFR VSBY. DO NOT HAVE ANY CONFIDENCE IN THE NAM
GENERATING MID DAY CONVECTION IN SOUTHEASTERN KS. THERE IS NO GOOD
EXPLANATION FOR THE NAMS DISJOINTED COOLING OF MID LEVEL TEMPS
WHICH WEAKENS THE CAP. THE RAP ON THE OTHER HAND SHOWS THE CAP
HOLDING THROUGH THE LATE AFTERNOON WITH SFC TEMPS WARMING TO
AROUND 90. THEREFORE WILL KEEP THE TERMINALS DRY THROUGH THE
FORECAST.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LEIGHTON
LONG TERM...CRAVEN
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1142 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 725 PM CDT FRI MAY 17 2013
WITH THE LATEST RAP AND NAM MODELS SHOWING THE STRATUS REMAINING
MAINLY TO THE SOUTHWEST OF THE FORECAST AREA LATE TONIGHT...AM A
LITTLE CONCERNED FOR SOME GROUND FOG FORMATION BETWEEN 08 AND 10Z
THINKING WINDS WILL BE LESS THAN 5 KTS AND SKIES MOSTLY CLEAR.
DEWPOINT TEMPS ACROSS SOUTHERN MO IN THE LOWER 60S AND A
PERSISTENT SOUTHEAST WIND SUGGEST DEWPOINTS ARE MOT LIKELY TO DROP
OFF MUCH TONIGHT. BECAUSE OF THIS HAVE INSERTED A MENTION OF
PATCHY FOG FOR LATE TONIGHT AND EARLY SATURDAY MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 342 PM CDT FRI MAY 17 2013
SCATTERED TO BROKEN STRATOCU DECK ACROSS THE EASTERN 2/3 OF THE
COUNTY WARNING AREA WILL GRADUALLY DECREASE AFT PEAK
HEATING...BEFORE REDEVELOPING/THICKENING AGAIN LATER TONIGHT AS
MOIST AXIS LIFTS NORTHWARD TOWARDS THE CWA. WILL KEEP THE FCST DRY
THROUGH TONIGHT...BUT INCREASE CLOUDS LATER AGAIN SOUTHWEST TO
NORTHEAST. ALTHOUGH NOT AS DENSE AS LAST NIGHT...STILL THINK SOME
FOG MAY FORM WITH THE STRATUS LATE...BUT NOT DENSE ENOUGH TO INSERT
INTO GRIDS AT THIS POINT. LOWS SHOULD BE IN THE LOW TO MIDDLE 60S.
EXPECT THIS STRATUS DECK SHOULD THIN AGAIN BY MIDDAY/AFTERNOON
SATURDAY ALLOWING FOR HIGH TEMPS TO WARM INTO THE MIDDLE 80S. MODELS
DIFFER ON WHETHER CAPPING INVERSION BY MIDDAY/AFTERNOON CAN BE
OVERCOME ENOUGH FOR SOME SCT CONVECTION TO DEVELOP AS A WEAK WAVE
APPROACHES FROM THE SOUTHWEST. HOWEVER...WITH A STRENGTHENING
ELEVATED MIXED LAYER WITH LITTLE IN THE WAY OF FORCING IN THAT
LAYER...FEEL THE MODELS MAY BE UNDER DOING CINH AND HAVE DECIDED TO
CONTINUE WITH A DRY FCST...OR MORE IN LINE WITH THE EC MODEL.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 342 PM CDT FRI MAY 17 2013
MODELS CONTINUE TO SIGNAL FOR SOME CONVECTION TO DEVELOP ABOVE THE
CAPPING INVERSION SATURDAY NIGHT AS THE LOW LEVEL JET INCREASES AS
WELL AS ISENTROPIC LIFT. WITH NOT HIGH CONFIDENCE WILL CONTINUE TO
KEEP POPS AROUND 20 PERCENT.
BY 12Z SUNDAY THE UPPER TROUGH AXIS WILL MOVE TO NEAR THE WESTERN
KANSAS BORDER. THE SURFACE LOW WILL CONTINUE TO DEEPEN IN WESTERN
KANSAS. SOME ELEVATED STORMS ARE POSSIBLE SUNDAY MORNING FROM ANY
OVERNIGHT DEVELOPMENT. THE UPPER TROUGH WILL MOVE OUT INTO THE
PLAINS SUNDAY TAKING ON A NEGATIVE TILT. THE TROUGH AXIS LOOKS TO
PASS TO THE EAST OF THE CWA SUNDAY NIGHT. ZERO TO 6 KM SHEAR OF 30
TO 40 KTS...1500-2500 J/KG OF ML CAPE ALONG WITH ABUNDANT MOISTURE
IN THE WARM SECTOR. LAPSE RATES STEEPEN AS THE UPPER TROUGH PIVOTS
NORTHEAST AND ERODES THE CAPPING INVERSION. WILL CONTINUE WITH
LIKELY CHANCES OF THUNDERSTORMS IN THE EASTERN 2/3RDS OF THE CWA ON
SUNDAY AFTERNOON WITH THE HIGHER POPS OVER EAST CENTRAL KANSAS
SUNDAY EVENING. GIVEN SHEAR AND INSTABILITY WITH ABUNDANT MOISTURE
STRONG TO SEVERE STORMS ARE POSSIBLE WITH LARGE HAIL AND DAMAGING
WINDS THE MAIN THREAT. THE TORNADO THREAT REMAINS SUNDAY AND SUNDAY
EVENING...ALTHOUGH NOT MUCH CURVATURE TO THE HODOGRAPHS AND TURNING
IN THE FORECAST HODOGRAPHS CANNOT RULE OUT ANY WITH SUPERCELLS.
MONDAY IS STILL A LITTLE BIT OF A QUESTION MARK AS TO HOW FAR
SOUTHEAST THE BOUNDARY WILL SET UP ACROSS EAST CENTRAL KANSAS SO
WILL CONTINUE TO KEEP THE HIGHER THUNDERSTORM CHANCES IN THE
SOUTHEAST CWA. STRONG TO SEVERE STORMS WILL AGAIN BE POSSIBLE MONDAY
AFTERNOON AND EVENING. THE UPPER LOW CONTINUE TO SPIN OVER THE
CENTRAL PLAINS THROUGH WEDNESDAY. THIS WILL KEEP SMALL CHANCES OF
SHOWERS AND THUNDERSTORMS TUESDAY THROUGH EARLY THURSDAY. A RIDGE
BUILDS OVER THE PLAINS LATE THURSDAY AND FRIDAY BRINGING AN END TO
THE PRECIPITATION CHANCES. FROM MONDAY THROUGH FRIDAY TEMPERATURES
WILL BE IN THE 70S FOR HIGHS AND 50S FOR LOWS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1142 PM CDT FRI MAY 17 2013
CONFIDENCE IN IFR VSBY IS IS DIMINISHING AS OBJECTIVE GUIDANCE HAS
COME IN AND BACKED OFF ON VSBY RESTRICTIONS AND WINDS HAVE NOT
BEEN AS LIGHT AS EXPECTED. STILL THINK THERE WILL BE ENOUGH
RADIATIONAL COOLING FOR SOME MVFR VSBY TO OCCUR...BUT WILL REMOVE
THE MENTION OF IFR VSBY. DO NOT HAVE ANY CONFIDENCE IN THE NAM
GENERATING MID DAY CONVECTION IN SOUTHEASTERN KS. THERE IS NO GOOD
EXPLANATION FOR THE NAMS DISJOINTED COOLING OF MID LEVEL TEMPS
WHICH WEAKENS THE CAP. THE RAP ON THE OTHER HAND SHOWS THE CAP
HOLDING THROUGH THE LATE AFTERNOON WITH SFC TEMPS WARMING TO
AROUND 90. THEREFORE WILL KEEP THE TERMINALS DRY THROUGH THE
FORECAST.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...WOLTERS
SHORT TERM...63
LONG TERM...53
AVIATION...WOLTERS
AREA FORECAST DISCUSSION
NWS JACKSON KY
1029 PM EDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 1029 PM EDT SUN MAY 19 2013
SHOWER ACTIVITY DISSIPATED ABOUT 2 HOURS AGO WITH NO MORE ACTIVITY
EXPECTED TONIGHT DESPITE THE HI RES MODELS TRYING TO SHOW MORE
DEVELOPMENT OVERNIGHT. NO REAL TRIGGERS WITH HIGH PRESSURE BUILDING
IN...SO NO REASON TO GO WITH ANY POPS OVERNIGHT. SKIES ARE BEGINNING
TO CLEAR OFF...AND I IMAGINE SOME FOG IS ALREADY DEVELOPING IN THE
VALLEYS. LOCALLY DENSE FOG IS EXPECTED GIVEN THE CLEARING SKIES.
FORECAST IS HANDLED WELL...SO NO UPDATE PLANNED RIGHT NOW.
UPDATE ISSUED AT 740 PM EDT SUN MAY 19 2013
THINGS HAVE QUIETED DOWN FOR MUCH OF THE AREA. HOWEVER...VERY
UNSTABLE AIRMASS CONTINUES TO HOLD ITS GROUND ALONG AND NORTH OF
I-64...WITH MANY LOCATIONS STILL AROUND 80 DEGREES AT THE MOMENT.
UPDATED EARLIER TO INCLUDE A MENTION OF HAIL AND WINDS AS WE HAVE
SEEN SOME PRETTY GOOD STORMS ACROSS CENTRAL KENTUCKY AND CAN`T RULE
OUT SOME STRONG STORMS ACROSS THE NORTHERN PORTION OF THE AREA
OVER THE NEXT FEW HOURS. AFTER SUNSET...STUFF SHOULD REALLY DROP
OFF...WITH A QUIET NIGHT ANTICIPATED. STILL SOME QUESTION AS TO HOW
EXTENSIVE THE FOG WILL BE TONIGHT. WITH DEWPOINTS RUNNING WELL ABOVE
THEIR READINGS FROM YESTERDAY AT THIS TIME...IF WE CAN CLEAR OUT
TONIGHT...THE POTENTIAL FOR DENSE FOG WOULD CERTAINLY INCREASE. WILL
CONTINUE TO EVALUATE THE NEED FOR ANY STATEMENTS FOR ADVISORIES OVER
THE NEXT FEW HOURS TO SEE HOW THE CLOUDS EVOLVE OR DISSIPATE.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 310 PM EDT SUN MAY 19 2013
MID/UPPER LOW OVER NORTHEAST KY WILL CONTINUE TO PULL AWAY WITH UPPER
RIDGING BUILDING INTO THE AREA FOR MONDAY. AN UPPER LEVEL LOCAL SPEED
MAXIMUM ON THE SOUTHERN SIDE OF THE LOW HAS HELPED SUPPORT THE
DEVELOPMENT OF NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE
SOUTHERN PART OF THE FORECAST AREA TODAY. SPEED MAX IS FORECAST TO WEAKEN
AND MOVE AWAY FROM THE AREA. THIS COMBINED WITH LOSS OF DAYTIME
HEATING SHOULD RESULT IN A QUICK DECREASE IN CONVECTION THIS EVENING.
THIS IS SUPPORTED BY THE 12Z NAM AND LATEST HRRR. THE HRRR DOES HAVE
SOME CONVECTION LINGERING TO AT LEAST MIDNIGHT...AND WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE SOUTHEAST THROUGH
THIS TIME. FOG WILL DEVELOP AGAIN TONIGHT...WITH LOCALLY DENSE FOG
ESPECIALLY IN AREAS WHERE RAIN FELL TODAY.
WITH UPPER RIDGING OVER THE AREA ON MONDAY EXPECT CONVECTION TO BE
LESS ORGANIZED...EVEN THOUGH LOW LEVEL LAPSE RATES AND SURFACE BASED
INSTABILITY WILL BE GREATER THAN TODAY. WHILE THERE WILL NOT BE ANY
UPPER FORCING LIKE TODAY THERE WILL BE NUMEROUS BOUNDARIES LEFT FROM
TODAYS CONVECTION...SO WILL GO WITH SLIGHT CHANCE TO CHANCE
PROBABILITIES OVER ALL BUT THE FAR WESTERN TIER OF COUNTIES FOR
MONDAY. EXPECT ANY CONVECTION ON MONDAY TO AGAIN QUICKLY DISSIPATE
DURING THE EVENING.
WITH SHORT RANGE SOIL MOISTURE AND DROUGHT INDICES
SHOWING WETTER THAN NORMAL CONDITIONS IN THE FORECAST AREA WILL
CONTINUE TO DISREGARD THE GFS MOS HIGH TEMPERATURES OF 90 DEGREES FOR
MONDAY. WILL GO MOSTLY WITH MIDDLE 80S. RECORD HIGHS FOR MONDAY ARE
85 IN 1987 AT JKL AND 88 IN 1962 AT LOZ. WILL ALSO LEAN TOWARDS THE
NAM MOS PROBABILITY OF RAIN CHANCE GUIDANCE WHICH KEEPS LOW CHANCES
FOR TONIGHT AND MONDAY NIGHT...WITH BEST CHANCE FOR MONDAY. THIS IS
THE COMPLETE OPPOSITE OF THE GFS MOS GUIDANCE WHICH PLACES LOW
PROBABILITIES ON MONDAY WITH THE BEST CHANCES TONIGHT AND MONDAY
NIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 310 PM EDT SUN MAY 19 2013
THE EXTENDED FORECAST BEGINS WITH A RIDGE OVER THE EAST COAST AND A
SERIES OF MID LEVEL DISTURBANCES PRESSING EAST ALONG THE NRN CONUS
BORDER. A WAVE IN THE ERN PLAINS HAS SOUTHERLY FLOW AT THE SFC
WHICH WILL BRING GULF MOISTURE INTO ERN KY. SCATTERED TO NUMEROUS
SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR WITHOUT MUCH ORGANIZATION
AS THE SFC LOW TAKES FORM AND MOVES INTO THE WRN GREAT LAKES. BY WED
THE COLD FRONT WILL MOVE INTO WRN KY AS THE MID LEVEL OPENS INTO A
WAVE AS IT PUSHES OVER THE ERN RIDGE. WED NIGHT WILL SEE A SERIES OF
WAVES CYCLE AROUND THE SRN EDGE OF THE 50H DISTURBANCE WITH
SCATTERED AREAS OF PCPN REFLECTED AT THE SFC. BY EARLY FRI MORNING
THE UPPER PATTERN HAS CHANGED TO A PLAINS RIDGE AND COASTAL TROFS.
SFC HIGH PRESSURE WILL DROP FROM THE NRN PLAINS AND BRING A PERIOD
OF DRY WEATHER. THAT WILL LAST THRU THE WEEKEND AS THE SFC HIGH
DRIFTS TOWARD THE EAST COAST WITH THE UPPER PATTERN BECOMING MORE
PROGRESSIVE.
FOR SENSIBLE WEATHER THE SOUTHERLY FLOW FROM THE GULF ON TUE WILL
BRING SCATTERED PCPN ALONG WITH TEMPS INTO THE MID 80S. THIS PATTERN
WILL CONTINUE THRU WED WITH OVERNIGHT LOWS RESTRICTED TO THE MID 60S
DUE TO HIGH DWPTS AND CLOUDS. THEN ON THU THE FIRST COLD FRONT WILL
CROSS ERN KY WITH SCATTERED STORMS AND COOLER TEMPS AS HIGHS ONLY
REACH THE UPPER 70S AND LOWS THU NIGHT DROP TO AROUND 60. WITH THE
SECOND SURGE OF COLD AIR FOLLOWING ON FRI LOOK FOR HIGHS IN THE MID
70S AND CLEARING LATE FRI WILL ALLOW OVERNIGHT LOWS TO DROP TO THE
MID 50S. THE COOL AIR WILL KEEP SAT HIGHS IN THE LOWER 70S IN SPITE
OF A REDUCTION IN CLOUDS EARLY AS THE DAYTIME MIXING WILL HELP
INCREASE CLOUD COVER TO COMPLEMENT THE COOLER NORTH WINDS. AS THE
DRIER AIR MOVES INTO ERN KY ON SUN THE WINDS WILL DIMINISH WITH THE
HIGH PRESSURE CROSSING TO OUR NORTH AND THE SUN WILL BEGIN THE
HEATING TO PUSH HIGHS BACK INTO THE MID 70S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 740 PM EDT SUN MAY 19 2013
VFR CONDITIONS SHOULD HOLD AT THE TAF SITES THROUGH THIS EVENING.
PLENTY OF QUESTIONS STILL ABOUND ABOUT HOW MUCH FOG WE WILL SEE
TONIGHT. MODELS DO NOT SEEM TO HAVE A GOOD HANDLE ON THE FOG
POTENTIAL TONIGHT. IF WE CAN CLEAR OUT...AREAS TO WIDESPREAD DENSE
FOG COULD DEVELOP WITH DEWPOINTS RUNNING FAIRLY HIGH AT THE MOMENT.
FOR NOW...GOING TO DROP AIRPORTS UNDER MINIMUMS LATE TONIGHT AS A
COMBINATION OF STRATUS OR FOG SHOULD GET THE JOB DONE. ADJUSTMENTS
MAY NEED TO BE MADE AT LATER TIMES AS WE SEE HOW CLOUD COVER EVOLVES
OVER THE NEXT FEW HOURS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...SBH
LONG TERM...DUSTY
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
740 PM EDT SUN MAY 19 2013
.UPDATE...
ISSUED AT 740 PM EDT SUN MAY 19 2013
THINGS HAVE QUIETED DOWN FOR MUCH OF THE AREA. HOWEVER...VERY
UNSTABLE AIRMASS CONTINUES TO HOLD ITS GROUND ALONG AND NORTH OF
I-64...WITH MANY LOCATIONS STILL AROUND 80 DEGREES AT THE MOMENT.
UPDATED EARLIER TO INCLUDE A MENTION OF HAIL AND WINDS AS WE HAVE
SEEN SOME PRETTY GOOD STORMS ACROSS CENTRAL KENTUCKY AND CAN`T RULE
OUT SOME STRONG STORMS ACROSS THE NORTHERN PORTION OF THE AREA
OVER THE NEXT FEW HOURS. AFTER SUNSET...STUFF SHOULD REALLY DROP
OFF...WITH A QUIET NIGHT ANTICIPATED. STILL SOME QUESTION AS TO HOW
EXTENSIVE THE FOG WILL BE TONIGHT. WITH DEWPOINTS RUNNING WELL ABOVE
THEIR READINGS FROM YESTERDAY AT THIS TIME...IF WE CAN CLEAR OUT
TONIGHT...THE POTENTIAL FOR DENSE FOG WOULD CERTAINLY INCREASE. WILL
CONTINUE TO EVALUATE THE NEED FOR ANY STATEMENTS FOR ADVISORIES OVER
THE NEXT FEW HOURS TO SEE HOW THE CLOUDS EVOLVE OR DISSIPATE.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 310 PM EDT SUN MAY 19 2013
MID/UPPER LOW OVER NORTHEAST KY WILL CONTINUE TO PULL AWAY WITH UPPER
RIDGING BUILDING INTO THE AREA FOR MONDAY. AN UPPER LEVEL LOCAL SPEED
MAXIMUM ON THE SOUTHERN SIDE OF THE LOW HAS HELPED SUPPORT THE
DEVELOPMENT OF NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE
SOUTHERN PART OF THE FORECAST AREA TODAY. SPEED MAX IS FORECAST TO WEAKEN
AND MOVE AWAY FROM THE AREA. THIS COMBINED WITH LOSS OF DAYTIME
HEATING SHOULD RESULT IN A QUICK DECREASE IN CONVECTION THIS EVENING.
THIS IS SUPPORTED BY THE 12Z NAM AND LATEST HRRR. THE HRRR DOES HAVE
SOME CONVECTION LINGERING TO AT LEAST MIDNIGHT...AND WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE SOUTHEAST THROUGH
THIS TIME. FOG WILL DEVELOP AGAIN TONIGHT...WITH LOCALLY DENSE FOG
ESPECIALLY IN AREAS WHERE RAIN FELL TODAY.
WITH UPPER RIDGING OVER THE AREA ON MONDAY EXPECT CONVECTION TO BE
LESS ORGANIZED...EVEN THOUGH LOW LEVEL LAPSE RATES AND SURFACE BASED
INSTABILITY WILL BE GREATER THAN TODAY. WHILE THERE WILL NOT BE ANY
UPPER FORCING LIKE TODAY THERE WILL BE NUMEROUS BOUNDARIES LEFT FROM
TODAYS CONVECTION...SO WILL GO WITH SLIGHT CHANCE TO CHANCE
PROBABILITIES OVER ALL BUT THE FAR WESTERN TIER OF COUNTIES FOR
MONDAY. EXPECT ANY CONVECTION ON MONDAY TO AGAIN QUICKLY DISSIPATE
DURING THE EVENING.
WITH SHORT RANGE SOIL MOISTURE AND DROUGHT INDICES
SHOWING WETTER THAN NORMAL CONDITIONS IN THE FORECAST AREA WILL
CONTINUE TO DISREGARD THE GFS MOS HIGH TEMPERATURES OF 90 DEGREES FOR
MONDAY. WILL GO MOSTLY WITH MIDDLE 80S. RECORD HIGHS FOR MONDAY ARE
85 IN 1987 AT JKL AND 88 IN 1962 AT LOZ. WILL ALSO LEAN TOWARDS THE
NAM MOS PROBABILITY OF RAIN CHANCE GUIDANCE WHICH KEEPS LOW CHANCES
FOR TONIGHT AND MONDAY NIGHT...WITH BEST CHANCE FOR MONDAY. THIS IS
THE COMPLETE OPPOSITE OF THE GFS MOS GUIDANCE WHICH PLACES LOW
PROBABILITIES ON MONDAY WITH THE BEST CHANCES TONIGHT AND MONDAY
NIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 310 PM EDT SUN MAY 19 2013
THE EXTENDED FORECAST BEGINS WITH A RIDGE OVER THE EAST COAST AND A
SERIES OF MID LEVEL DISTURBANCES PRESSING EAST ALONG THE NRN CONUS
BORDER. A WAVE IN THE ERN PLAINS HAS SOUTHERLY FLOW AT THE SFC
WHICH WILL BRING GULF MOISTURE INTO ERN KY. SCATTERED TO NUMEROUS
SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR WITHOUT MUCH ORGANIZATION
AS THE SFC LOW TAKES FORM AND MOVES INTO THE WRN GREAT LAKES. BY WED
THE COLD FRONT WILL MOVE INTO WRN KY AS THE MID LEVEL OPENS INTO A
WAVE AS IT PUSHES OVER THE ERN RIDGE. WED NIGHT WILL SEE A SERIES OF
WAVES CYCLE AROUND THE SRN EDGE OF THE 50H DISTURBANCE WITH
SCATTERED AREAS OF PCPN REFLECTED AT THE SFC. BY EARLY FRI MORNING
THE UPPER PATTERN HAS CHANGED TO A PLAINS RIDGE AND COASTAL TROFS.
SFC HIGH PRESSURE WILL DROP FROM THE NRN PLAINS AND BRING A PERIOD
OF DRY WEATHER. THAT WILL LAST THRU THE WEEKEND AS THE SFC HIGH
DRIFTS TOWARD THE EAST COAST WITH THE UPPER PATTERN BECOMING MORE
PROGRESSIVE.
FOR SENSIBLE WEATHER THE SOUTHERLY FLOW FROM THE GULF ON TUE WILL
BRING SCATTERED PCPN ALONG WITH TEMPS INTO THE MID 80S. THIS PATTERN
WILL CONTINUE THRU WED WITH OVERNIGHT LOWS RESTRICTED TO THE MID 60S
DUE TO HIGH DWPTS AND CLOUDS. THEN ON THU THE FIRST COLD FRONT WILL
CROSS ERN KY WITH SCATTERED STORMS AND COOLER TEMPS AS HIGHS ONLY
REACH THE UPPER 70S AND LOWS THU NIGHT DROP TO AROUND 60. WITH THE
SECOND SURGE OF COLD AIR FOLLOWING ON FRI LOOK FOR HIGHS IN THE MID
70S AND CLEARING LATE FRI WILL ALLOW OVERNIGHT LOWS TO DROP TO THE
MID 50S. THE COOL AIR WILL KEEP SAT HIGHS IN THE LOWER 70S IN SPITE
OF A REDUCTION IN CLOUDS EARLY AS THE DAYTIME MIXING WILL HELP
INCREASE CLOUD COVER TO COMPLEMENT THE COOLER NORTH WINDS. AS THE
DRIER AIR MOVES INTO ERN KY ON SUN THE WINDS WILL DIMINISH WITH THE
HIGH PRESSURE CROSSING TO OUR NORTH AND THE SUN WILL BEGIN THE
HEATING TO PUSH HIGHS BACK INTO THE MID 70S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 740 PM EDT SUN MAY 19 2013
VFR CONDITIONS SHOULD HOLD AT THE TAF SITES THROUGH THIS EVENING.
PLENTY OF QUESTIONS STILL ABOUND ABOUT HOW MUCH FOG WE WILL SEE
TONIGHT. MODELS DO NOT SEEM TO HAVE A GOOD HANDLE ON THE FOG
POTENTIAL TONIGHT. IF WE CAN CLEAR OUT...AREAS TO WIDESPREAD DENSE
FOG COULD DEVELOP WITH DEWPOINTS RUNNING FAIRLY HIGH AT THE MOMENT.
FOR NOW...GOING TO DROP AIRPORTS UNDER MINIMUMS LATE TONIGHT AS A
COMBINATION OF STRATUS OR FOG SHOULD GET THE JOB DONE. ADJUSTMENTS
MAY NEED TO BE MADE AT LATER TIMES AS WE SEE HOW CLOUD COVER EVOLVES
OVER THE NEXT FEW HOURS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...SBH
LONG TERM...DUSTY
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
359 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A FRONTAL BOUNDARY WILL STALL SOUTH OF THE AREA THIS WEEKEND OVER
THE CENTRAL APPALACHIANS AND SOUTHERN MID-ATLANTIC STATES WHILE
ONSHORE FLOW KEEPS THE FORECAST AREA SEASONABLY COOL. THE FRONTAL
BOUNDARY WILL LIFT NORTH OF THE AREA EARLY IN THE WEEK FOLLOWED BY
HIGH PRESSURE BUILDING OVER THE EASTERN STATES THROUGH MIDWEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
FRONTAL BOUNDARY HAS BECOME NEARLY STATIONARY...LOCATED ALONG THE
COASTAL VIRGINIA/NORTH CAROLINA BORDER AND SNAKING ITS WAY BACK
THROUGH/UP THE CENTRAL APPALACHIANS. MEANWHILE...HIGH PRESSURE WAS
LOCATED ALONG THE NEW ENGLAND COAST.
RADAR IMAGERY SHOWED SHOWERS WITH EMBEDDED THUNDERSTORMS ACROSS
CENTRAL AND SOUTHERN VIRGINIA...TO NORTH OF THE BOUNDARY IN A ZONE
OF ISENTROPIC LIFT/ELEVATED INSTABILITY ENHANCED BY PVA FROM A VORT
MAX AT 500 MB. SHOWERS HAVE SNEAKED UP INTO THE CENTRAL VIRGINIA
FOOTHILLS AREA OF THE CWA EARLY THIS MORNING.
THIS FORECAST CYCLE...WHAT IS CERTAIN OVER THE NEXT 24 HOURS IS THAT
EAST-SOUTHEAST FLOW IN THE LOW LEVELS WILL PREVAIL
TODAY/TONIGHT...RESULTING IN CLOUDY SKIES. THIS WILL LEAD TO COOLER
TEMPERATURES TODAY AND GUIDANCE IS IN SOMEWHAT BETTER AGREEMENT THAN
24 HOURS AGO FAVORING THE PREVIOUS COOLER SOLUTION FOR BELOW NORMAL
MAXIMA. BLENDED BIAS CORRECTED MAV/MET WHICH FAVORS UPPER 60S TO
LOWER 70S MAXIMA TODAY...AND THEN MINIMA ABOVE NORMAL TONIGHT IN THE
UPPER 50S TO LOWER 60S.
WHAT IS UNCERTAIN ARE THE DETAILS REGARDING PRECIPITATION. PLENTY OF
DIVERGENCE AMONG THE MODELS IS ALREADY APPARENT WITH THE SHOWERS ON
RADAR NOW...AND WHAT THEIR FATE WILL BE LATER THIS MORNING AND
BEYOND. 03Z HRRR MOVES/FURTHER DEVELOPS THESE SHOWERS TO THE NORTH
THROUGH MORNING...TAKING THEM ALL THE WAY TO THE MASON DIXON LINE BY
LATE MORNING. WRF-ARW/GFS SOLUTIONS GENERALLY KEEP SHOWERS ACROSS
THE SOUTHERN THIRD TO HALF OF THE CWA DURING THE DAY TODAY. THE NAM
AND SREFS ARE SOMEWHERE IN BETWEEN.
INITIALLY...FORECAST IS HEAVILY WEIGHTED TOWARD THE WRF-ARW/GFS
SOLUTIONS /AND RADAR TRENDS/ THIS MORNING THEN BLENDS WITH THE
NAM/SREFS SOLUTIONS FOR THE AFTERNOON AND INTO TONIGHT WITH THE
THINKING THAT LIFT AND THUS SHOWERS EXPAND TO THE NORTH WITH TIME
WITH LIKELY POPS ACROSS THE ENTIRE CWA OVERNIGHT. OBVIOUSLY IF THE
HRRR IS CORRECT THERE WILL BE RAINFALL FURTHER NORTH AND SOONER
THAN WHAT THE FORECAST REFLECTS...AND WILL CONTINUE TO MONITOR
THROUGH THE MORNING BUT FOR NOW THIS HAS BEEN LARGELY DISCOUNTED.
COOL WEDGE WILL BE PRESENT ACROSS MUCH OF THE CWA TO PRECLUDE
THUNDER. HOWEVER GUIDANCE SUGGESTS SOME INSTABILITY ACROSS THE
SOUTHWEST CWA THIS AFTERNOON/EARLY EVENING CLOSER TO THE SNAKING
FRONTAL BOUNDARY. THEREFORE...CONTINUE TO INCLUDE CHANCE OF THUNDER
IN THIS AREA AND ANY CONVECTION MAY BE EFFICIENT RAINFALL PRODUCERS
FOR LOCALLY HEAVY RAINFALL.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
FRONTAL BOUNDARY WILL REMAIN STALLED ACROSS SRN VA ON SUN WHILE SFC
RIDGE FROM HIPRES OFF THE NEW ENGLAND COAST WILL EXTEND WWD INTO NJ
AND PA. SFC PATTERN WILL YIELD A CONTINUED ONSHORE FLOW ACROSS THE
CWA ON SUN. REMNANT MID-LVL SHORTWAVE TROUGH WILL MEANDER OVER THE
CENTRAL APPALACHIANS AS IT REMAINS EMBEDDED WITHIN WEAK STEERING
PATTERN OF THE ERN CONUS RIDGE. FLOW VEERS WITH HEIGHT WITH SLY FLOW
AT H8-7 PROMOTING ISENTROPIC LIFT. CLOUDS AND PERIODS OF SHOWERS
EXPECTED ON SUN. THE HEAVIEST QPF AND CAT POPS RESIDE OVER CENTRAL
VA AND LWR SRN MD...WHERE LIFT MAY BECOME ENHANCED NEAR THE BOUNDARY
AND NORTH OF THE MID-LVL TROUGH. MOST OF THE CWA WILL BE WEDGED IN
STABLE MARINE AIRMASS ALTHOUGH LOCATIONS IN CENTRAL VA MAY TAP INTO
SOME INSTABILITY CLOSER TO THE BOUNDARY. WILL NEED TO MONITOR THE
CONDITIONAL RISK FOR FLOODING OVER THESE AREAS IF CONVECTION
DEVELOPS. WPC HAS HIGHLIGHTED CENTRAL VA WITH A SLIGHT RISK FOR
EXCESSIVE RAINFALL ON SUN.
CLOUDS AND ONSHORE FLOW WILL LIMIT DIURNAL HEATING/COOLING SUN-SUN
NGT. HIGHS NEAR 70F ON SUN AND LOWS IN THE 60S SUN NGT WILL BE
COMMON.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
THE MID-ATLANTIC REGION WILL BE SITUATED ALONG WRN PERIPHERY OF AN
UPPER RIDGE THROUGH MIDWEEK. PERSISTENT AND DEEP RETURN FLOW AROUND
THE RIDGE WILL CONTINUE TO SUPPLY WARM/MOIST AIR FOR OUR AREA. WITH
THE PREVIOUSLY STALLED FRONTAL BOUNDARY LIFTING NORTH OF THE AREA ON
MON...INSTABILITY AND MOISTURE WILL BE GREATER IN WARM SECTOR. DAILY
CHANCES FOR SHOWERS AND TSTMS WILL BE HIGHEST DURING THE PEAK
HEATING HRS. DURING THE FIRST HALF OF THE WORK WEEK...MON EXPECTED
TO HAVE THE BEST COVERAGE OF PRECIP WITH THE LINGERING MID-LVL
SHORTWAVE TROUGH NEARBY. POPS TUE AND WED WERE CONFINED TO THE
HIGHER TERRAIN WITH OROGRAPHIC LIFT THE PRIMARY DRIVING MECHANISM
FOR DIURNAL CONVECTION. MAX TEMPS NEAR 80F ON MON AND MU80S TUE/WED.
CHANCES FOR SHOWERS AND STORMS INCREASE LATE WEEK WITH THE APPROACH
OF A MIDWEST TROUGH. WARM/HUMID AIRMASS REMAINS IN PLACE DURING THIS
TIME.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS MENTIONED IN THE NEAR TERM DISCUSSION...THERE IS SOME UNCERTAINTY
REGARDING ONSET OF PRECIPITATION. HAVE DISCOUNTED RECENT RUNS OF THE
HRRR AND BLENDED OTHER MODELS FOR ONSET TIMING. THERE ALSO IS SOME
UNCERTAINTY REGARDING THE ONSET OF FLIGHT RESTRICTIONS. WITH
EAST-SOUTHEAST FLOW...EXPECT CIGS TO FALL TODAY/TONIGHT. CLOSELY
FOLLOWED A GFS LAMP SOLUTION...WHICH BRINGS IFR CONDITIONS MAINLY
AFTER DARK AND THEN LIFR CONDITIONS AFTER MIDNIGHT. IF PRECIPITATION
DEVELOPS SOONER THAN CURRENTLY FORECAST...THEN LOWER FLIGHT
CONDITIONS MAY ALSO DEVELOP SOONER. IN COOL WEDGE...AM NOT EXPECTING
A CHANCE OF THUNDER THIS AFTERNOON AT MOST TAF SITES EXCEPT FOR CHO
WHERE THERE WILL BE SOME INSTABILITY HOWEVER CONFIDENCE IS TOO LOW
TO MENTION AT CHO AT THIS POINT.
MVFR CIGS SUN WITH ONSHORE FLOW CONTINUING. CIGS LIKELY RETURN TO
IFR SUN NGT. WARM FRONT EVENTUALLY LIFTS NORTH OF THE REGION ON MON.
FLIGHT RULES RETURN TO VFR ERY NEXT WEEK...ALTHOUGH BRIEF
RESTRICTIONS POSSIBLE IN SHRA/TSRA.
&&
.MARINE...
WITH HIGH PRESSURE MOVING OFF THE NEW ENGLAND COAST AND A FRONTAL
BOUNDARY STALLED TO THE SOUTH OF THE WATERS...EAST-SOUTHEAST WINDS
WILL SET UP TODAY/TONIGHT. WHILE WE EXPECT WINDS TO PREVAIL 10 TO 15
KT...SOME LOCAL ENHANCEMENT IS EXPECTED ALONG THE LOWER TIDAL
POTOMAC RIVER/LOWER MD CHESAPEAKE BAY WHERE A SCA IS IN EFFECT
TODAY. THIS COULD NEED TO BE EXTENDED INTO TONIGHT. IN
ADDITION...SOMETIMES THIS FLOW IS UNDER-FORECAST BY THE MODELS AND
WILL HAVE TO MONITOR THE NEED FOR NORTHERN EXPANSION UP THE CHANNEL
OF THE BAY.
ELY FLOW 10-15 KT ON SUN. WINDS BECOME SLY ONCE A WARM FRONT PASSES
THRU ON MON. SCA MAY BE NEEDED MON FOR THE MARINE ZONES THAT ARE
SUSCEPTIBLE TO SLY-CHANNELING.
&&
.TIDES/COASTAL FLOODING...
POSITIVE TIDAL ANOMALIES WILL GRADUALLY INCREASE THRUOUT THE
WEEKEND AS ONSHORE FLOW PERSISTS. SLY WINDS DEVELOP ON MON WHEN A
WARM FRONT LIFTS NORTH OF THE AREA. WILL NEED TO MONITOR TIDAL
LVLS THOUGH THE THREAT OF COASTAL FLOODING WILL BE RELATIVELY LOW
JUST PAST THE FIRST QUARTER MOON.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR ANZ534-537-543.
&&
$$
SYNOPSIS...JRK
NEAR TERM...BPP
SHORT TERM...JRK
LONG TERM...JRK
AVIATION...BPP/JRK
MARINE...BPP/JRK
TIDES/COASTAL FLOODING...JRK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
147 PM EDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT SAT MAY 18 2013
IN THE LARGE SCALE...TROUGH OVER THE ROCKIES WILL SLIDE ONTO THE
HIGH PLAINS BY SUNDAY MORNING ALLOWING RIDGING TO SLIGHTLY BUILD
OVER THE WESTERN GREAT LAKES. ALTHOUGH SFC-H85 TROUGHING OVER THE
DAKOTAS DOES NOT MOVE MUCH TO THE EAST...IT IS ENOUGH TO INCREASE
LOW-LEVEL SOUTHERLY FLOW ACROSS THE UPPER GREAT LAKES. PATTERN IS
SERVING TO INCREASE MOISTURE /PWATS 1.15 OF 1.31 INCHES AT GRB AND
MPX OR AROUND 200 PCT OF NORMAL/ IN WAKE OF DRY SFC HIGH THAT HAS
BEEN ESTABLISHED OVER THE AREA FOR MOST OF THIS WEEK. REGIONAL RADAR
SHOWS DECAYING ECHOES OVER NORTHERN WISCONSIN. MUCH MORE ORGANIZED
AREA OF SHRA/TSRA HAVE DEVELOPED SINCE 03Z FROM CENTRAL MINNESOTA
INTO WEST CENTRAL WISCONSIN ALONG H85 WARM FRONT/GRADIENT OF H85
THETA-E. ADDITIONAL AREA OF SHRA/TSRA SPREADING ACROSS NORTHEAST
SOUTH DAKOTA INTO SOUTHEAST NORTH DAKOTA NEAR CONVECTIVE INDUCED
SHORTAVE/H7-H3 DIFFERENTIAL PVA AND CLOSE TO H7 MOISTURE TRANSPORT.
JUST RECENTLY ANOTHER LARGE CLUSTER OF SHRA/TSRA HAVE FORMED IN THE
WARM AIR ADVECTION REGIME BTWN THESE TWO INITIAL AREAS OF PRECIP.
GIVEN EXTENT OF SHRA/TSRA UPSTREAM OF CWA THIS MORNING AND SINCE
H85-H7 MOISTURE ADVECTION IS FORECAST WEST TO EAST ACROSS CWA
THROUGH THE DAY...INCREASED POPS FOR MOST OF THE WEST AND NORTHERN
CWA AS AT LEAST MULTIPLE REMNANTS OF THIS CONVECTION SHOULD MAKE IT
INTO UPR MICHIGAN. LEANED ON THE NCEP WRF MODELS AND RECENT HRRR AND
EXTRAPOLATION OF LATEST HRRR TO CREATE POPS. RESULT IS LIKELY POPS
MOST OF THE DAY OVER THE WEST HALF...WITH SMALLER CHANCES FARTHER
EAST AS THE RAIN RUNS INTO THE VERY DRY AIRMASS ASSOCIATED WITH SFC
HIGH TO THE EAST. MAJORITY OF TSRA THUS FAR STAYING OVER NORTHERN
MINNESOTA ON GRADIENT OF 1-6KM MUCAPE RESERVOIR. HINT IN MODELS
THAT EASTERN EDGE OF INSTABILITY GRADIENT SLIDES TOWARD WESTERN UPR
MICHIGAN SO HAVE INCLUDED SLIGHT CHANCES FOR TSRA. CONVECTION IS
ELEVATED AND MID-LEVEL LAPSE RATES BARELY GET ABOVE 6C/KM. MAIN
ISSUE WILL BE HEAVY DOWNPOURS AND LIGHTNING STRIKES. TEMPS TODAY
A BIT TOUGH TO FIGURE OUT. EAST GRADIENT WINDS SHOULD KEEP KEWEENAW
CHILLY WITH READINGS STAYING BLO 50 DEGREES. MIXING TO H9 IS PROBABLY
IT WHERE CLOUDS/RAIN PERSIST MOST OF THE DAY. THIS SUPPORTS MAJORITY
OF CWA SEEING HIGHS IN THE 60S...EVENTUALLY...ONCE THE STEADIER RAIN
TAPERS OFF THIS AFTN. SFC WARM FRONT MAY TRY TO POKE INTO FAR SW CWA
LATE IN THE DAY. IF THIS OCCURS AND PRECIP TAPERS OFF/ENDS...THEN
THERE IS POTENTIAL FOR HIGHS TO PUSH WELL INTO THE 70S FROM IWD TO
IMT.
H85 FRONT LIFTS NORTH OF MOST CWA THIS EVENING. KEWEENAW STILL CLOSE
ENOUGH TO FRONT AND WITHIN THE RIBBON OF PERSISTENT MOISTURE
ADVECTION SO KEPT SHRA/ISOLD TSRA THERE THROUGH THE EVENING. DRYING
TREND TAKES HOLD OVERNIGHT AS THE FOCUS FOR SHRA/TSRA...H85 WARM
FRONT AND THETA-E GRADIENT...LIFTS WELL TO NORTH OF UPR MICHIGAN.
KEPT SMALL POPS IN AT ISLE ROYALE LATE TONIGHT THOUGH. TEMPS MOSTLY
IN THE 40S EAST WITH FLOW OFF LK MICHIGAN. LESS MODIFIED AIR FARTHER
WEST ALLOWS MINS TO ONLY FALL INTO THE LOW-MID 50S ALONG LK SUPERIOR
AROUND IWD TO ONTONAGON AND EAST TO BARAGA/L`ANSE AND MARQUETTE
AREAS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 510 AM EDT SAT MAY 18 2013
NAM SHOWS THE 500 MB RIDGE OVER THE EASTERN U.S. 12Z SUN WITH
TROUGHING IN THE ROCKIES. THE TROUGH MOVES EAST ON SUNDAY AND PUSHES
THE RIDGE INTO THE LOWER GREAT LAKES 12Z MON WHERE THE MOVEMENT
EASTWARD STOPS THROUGH 12Z TUE. NAM HAS SOME DEEPER MOISTURE AND
850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA 12Z SUN ONWARD. GFS
SHOWS ABOUT THE SAME THING AS WELL.
THIS PERIOD LOOKS PRETTY WET STARTING WITH SUN AFTERNOON THROUGH MON
NIGHT. WITH SLOW MOVEMENT OF SYSTEM INTO AND THROUGH THE AREA AND
ALSO A WARM FRONT NEAR AND TO THE SOUTH OF THE AREA...THIS SETS UP
THE CWA FOR A WIDESPREAD AND LONG LIVED RAIN EVENT WITH SOME HEAVY
RAIN POSSIBLE. AM FORECASTING ANYWHERE FROM .67 INCH OF QPF OVER THE
SOUTH...TO 1.15 INCHES OVER THE EAST TO OVER 2 INCHES OF RAIN IN THE
FAR WEST NEAR IRONWOOD FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT
AND THIS DOES NOT SEEM UNREASONABLE WITH PLENTY OF MOISTURE TO THE
SOUTH OF THE AREA AND SLOW SYSTEM MOVEMENT. FOR THIS REASON...BUMPED
POPS UP A BIT TO LIKELY TO CATEGORICAL FOR MOST OF THE CWA THROUGH
THEN. SHOULD SEE SOME SUNSHINE ON SUNDAY. MADE A FEW ADJUSTMENTS TO
TEMPERATURES BASED ON LAKE BREEZES AND WIND DIRECTIONS AND LOWERED
THEM A BIT NEAR THE GREAT LAKES SHORELINES. OTHER THAN THAT...NO
REAL BIG CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW AND TROUGH
IN THE NORTHERN AND CENTRAL PLAINS 12Z TUE WHICH MOVE LITTLE INTO
12Z WED. BY 12Z THU...THE TROUGH AND LOW GET PUSHED A BIT FURTHER
EAST TO THE UPPER GREAT LAKES REGION. THE TROUGH AND LOW MOVE
THROUGH BY 12Z FRI WITH RIDGING BUILDING INTO THE PLAINS LATE ON
FRI. SYSTEM WILL BE SLOW TO MOVE THROUGH THE AREA...SO A COUPLE OF
DAYS OF WIDESPREAD RAIN ARE NOT OUT OF THE QUESTION ALONG WITH
COOLER TEMPERATURES WITH GRADUAL SOUTHWARD MOVEMENT OF THE SYSTEM
AWAY FROM THE AREA. THU INTO FRI...THINGS START TO DRY OUT WITH A
COLD FRONT WELL SOUTH OF THE AREA. TEMPERATURES SLIP TO SLIGHTLY
BELOW NORMAL THIS PERIOD. POPS WILL BE HIGHEST IN THE SOUTH CLOSER
TO A WARM FRONT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 146 PM EDT SAT MAY 18 2013
A WARM FNT MOVING IN FM THE SOUTH WILL BRING SOME -SHRA/MVFR CIGS
/LIFR CIGS AT CMX WITH UPSLOPE FLOW/...MAINLY AT IWD/CMX WHERE LLVL
WARM/MOIST ADVCTN WL BE MOST PRONOUNCED. MOIST UPSLOPE FLOW OFF LK
SUPERIOR MAY RESULT IN IFR CONDITIONS INTO THIS EVENING. FOLLOWING
THE WARM FROPA TONIGHT...EXPECT WSHFT TO THE S WITH RETURN TO
PREDOMINANT VFR WX. THE ONLY EXCEPTION WL BE AT CMX...WHERE
PERSISTENT UPSLOPE ESE WIND AND MOISTER LLVL AIR WL RESULT IN
LINGERING MVFR CONDITIONS THROUGH MUCH OF THE NIGHT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT SAT MAY 18 2013
HEADING THRU EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE UPPER
LAKES WILL SLOWLY TIGHTEN BETWEEN LOW PRESSURE SLOWLY MOVING FROM
THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRESSURE
BUILDING IN THE VICINITY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING TO ALMOST 30 KNOTS BY MON AND
MON NIGHT...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...07
AVIATION...TITUS
MARINE...07
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
749 AM EDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT SAT MAY 18 2013
IN THE LARGE SCALE...TROUGH OVER THE ROCKIES WILL SLIDE ONTO THE
HIGH PLAINS BY SUNDAY MORNING ALLOWING RIDGING TO SLIGHTLY BUILD
OVER THE WESTERN GREAT LAKES. ALTHOUGH SFC-H85 TROUGHING OVER THE
DAKOTAS DOES NOT MOVE MUCH TO THE EAST...IT IS ENOUGH TO INCREASE
LOW-LEVEL SOUTHERLY FLOW ACROSS THE UPPER GREAT LAKES. PATTERN IS
SERVING TO INCREASE MOISTURE /PWATS 1.15 OF 1.31 INCHES AT GRB AND
MPX OR AROUND 200 PCT OF NORMAL/ IN WAKE OF DRY SFC HIGH THAT HAS
BEEN ESTABLISHED OVER THE AREA FOR MOST OF THIS WEEK. REGIONAL RADAR
SHOWS DECAYING ECHOES OVER NORTHERN WISCONSIN. MUCH MORE ORGANIZED
AREA OF SHRA/TSRA HAVE DEVELOPED SINCE 03Z FROM CENTRAL MINNESOTA
INTO WEST CENTRAL WISCONSIN ALONG H85 WARM FRONT/GRADIENT OF H85
THETA-E. ADDITIONAL AREA OF SHRA/TSRA SPREADING ACROSS NORTHEAST
SOUTH DAKOTA INTO SOUTHEAST NORTH DAKOTA NEAR CONVECTIVE INDUCED
SHORTAVE/H7-H3 DIFFERENTIAL PVA AND CLOSE TO H7 MOISTURE TRANSPORT.
JUST RECENTLY ANOTHER LARGE CLUSTER OF SHRA/TSRA HAVE FORMED IN THE
WARM AIR ADVECTION REGIME BTWN THESE TWO INITIAL AREAS OF PRECIP.
GIVEN EXTENT OF SHRA/TSRA UPSTREAM OF CWA THIS MORNING AND SINCE
H85-H7 MOISTURE ADVECTION IS FORECAST WEST TO EAST ACROSS CWA
THROUGH THE DAY...INCREASED POPS FOR MOST OF THE WEST AND NORTHERN
CWA AS AT LEAST MULTIPLE REMNANTS OF THIS CONVECTION SHOULD MAKE IT
INTO UPR MICHIGAN. LEANED ON THE NCEP WRF MODELS AND RECENT HRRR AND
EXTRAPOLATION OF LATEST HRRR TO CREATE POPS. RESULT IS LIKELY POPS
MOST OF THE DAY OVER THE WEST HALF...WITH SMALLER CHANCES FARTHER
EAST AS THE RAIN RUNS INTO THE VERY DRY AIRMASS ASSOCIATED WITH SFC
HIGH TO THE EAST. MAJORITY OF TSRA THUS FAR STAYING OVER NORTHERN
MINNESOTA ON GRADIENT OF 1-6KM MUCAPE RESERVOIR. HINT IN MODELS
THAT EASTERN EDGE OF INSTABILITY GRADIENT SLIDES TOWARD WESTERN UPR
MICHIGAN SO HAVE INCLUDED SLIGHT CHANCES FOR TSRA. CONVECTION IS
ELEVATED AND MID-LEVEL LAPSE RATES BARELY GET ABOVE 6C/KM. MAIN
ISSUE WILL BE HEAVY DOWNPOURS AND LIGHTNING STRIKES. TEMPS TODAY
A BIT TOUGH TO FIGURE OUT. EAST GRADIENT WINDS SHOULD KEEP KEWEENAW
CHILLY WITH READINGS STAYING BLO 50 DEGREES. MIXING TO H9 IS PROBABLY
IT WHERE CLOUDS/RAIN PERSIST MOST OF THE DAY. THIS SUPPORTS MAJORITY
OF CWA SEEING HIGHS IN THE 60S...EVENTUALLY...ONCE THE STEADIER RAIN
TAPERS OFF THIS AFTN. SFC WARM FRONT MAY TRY TO POKE INTO FAR SW CWA
LATE IN THE DAY. IF THIS OCCURS AND PRECIP TAPERS OFF/ENDS...THEN
THERE IS POTENTIAL FOR HIGHS TO PUSH WELL INTO THE 70S FROM IWD TO
IMT.
H85 FRONT LIFTS NORTH OF MOST CWA THIS EVENING. KEWEENAW STILL CLOSE
ENOUGH TO FRONT AND WITHIN THE RIBBON OF PERSISTENT MOISTURE
ADVECTION SO KEPT SHRA/ISOLD TSRA THERE THROUGH THE EVENING. DRYING
TREND TAKES HOLD OVERNIGHT AS THE FOCUS FOR SHRA/TSRA...H85 WARM
FRONT AND THETA-E GRADIENT...LIFTS WELL TO NORTH OF UPR MICHIGAN.
KEPT SMALL POPS IN AT ISLE ROYALE LATE TONIGHT THOUGH. TEMPS MOSTLY
IN THE 40S EAST WITH FLOW OFF LK MICHIGAN. LESS MODIFIED AIR FARTHER
WEST ALLOWS MINS TO ONLY FALL INTO THE LOW-MID 50S ALONG LK SUPERIOR
AROUND IWD TO ONTONAGON AND EAST TO BARAGA/L`ANSE AND MARQUETTE
AREAS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 510 AM EDT SAT MAY 18 2013
NAM SHOWS THE 500 MB RIDGE OVER THE EASTERN U.S. 12Z SUN WITH
TROUGHING IN THE ROCKIES. THE TROUGH MOVES EAST ON SUNDAY AND PUSHES
THE RIDGE INTO THE LOWER GREAT LAKES 12Z MON WHERE THE MOVEMENT
EASTWARD STOPS THROUGH 12Z TUE. NAM HAS SOME DEEPER MOISTURE AND
850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA 12Z SUN ONWARD. GFS
SHOWS ABOUT THE SAME THING AS WELL.
THIS PERIOD LOOKS PRETTY WET STARTING WITH SUN AFTERNOON THROUGH MON
NIGHT. WITH SLOW MOVEMENT OF SYSTEM INTO AND THROUGH THE AREA AND
ALSO A WARM FRONT NEAR AND TO THE SOUTH OF THE AREA...THIS SETS UP
THE CWA FOR A WIDESPREAD AND LONG LIVED RAIN EVENT WITH SOME HEAVY
RAIN POSSIBLE. AM FORECASTING ANYWHERE FROM .67 INCH OF QPF OVER THE
SOUTH...TO 1.15 INCHES OVER THE EAST TO OVER 2 INCHES OF RAIN IN THE
FAR WEST NEAR IRONWOOD FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT
AND THIS DOES NOT SEEM UNREASONABLE WITH PLENTY OF MOISTURE TO THE
SOUTH OF THE AREA AND SLOW SYSTEM MOVEMENT. FOR THIS REASON...BUMPED
POPS UP A BIT TO LIKELY TO CATEGORICAL FOR MOST OF THE CWA THROUGH
THEN. SHOULD SEE SOME SUNSHINE ON SUNDAY. MADE A FEW ADJUSTMENTS TO
TEMPERATURES BASED ON LAKE BREEZES AND WIND DIRECTIONS AND LOWERED
THEM A BIT NEAR THE GREAT LAKES SHORELINES. OTHER THAN THAT...NO
REAL BIG CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW AND TROUGH
IN THE NORTHERN AND CENTRAL PLAINS 12Z TUE WHICH MOVE LITTLE INTO
12Z WED. BY 12Z THU...THE TROUGH AND LOW GET PUSHED A BIT FURTHER
EAST TO THE UPPER GREAT LAKES REGION. THE TROUGH AND LOW MOVE
THROUGH BY 12Z FRI WITH RIDGING BUILDING INTO THE PLAINS LATE ON
FRI. SYSTEM WILL BE SLOW TO MOVE THROUGH THE AREA...SO A COUPLE OF
DAYS OF WIDESPREAD RAIN ARE NOT OUT OF THE QUESTION ALONG WITH
COOLER TEMPERATURES WITH GRADUAL SOUTHWARD MOVEMENT OF THE SYSTEM
AWAY FROM THE AREA. THU INTO FRI...THINGS START TO DRY OUT WITH A
COLD FRONT WELL SOUTH OF THE AREA. TEMPERATURES SLIP TO SLIGHTLY
BELOW NORMAL THIS PERIOD. POPS WILL BE HIGHEST IN THE SOUTH CLOSER
TO A WARM FRONT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 747 AM EDT SAT MAY 18 2013
A WARM FNT MOVING IN FM THE SOUTH WILL BRING SOME -SHRA/MVFR
CIGS...MAINLY AT IWD/CMX WHERE LLVL WARM/MOIST ADVCTN WL BE MOST
PRONOUNCED. MOIST UPSLOPE FLOW OFF LK SUPERIOR MAY RESULT IN IFR
CONDITIONS AT CMX THIS AFTN AND EVENING. FOLLOWING THE WARM FROPA
TONIGHT...EXPECT WSHFT TO THE S WITH RETURN TO PREDOMINANT VFR WX.
THE ONLY EXCEPTION WL BE AT CMX...WHERE PERSISTENT UPSLOPE ESE WIND
AND MOISTER LLVL AIR WL RESULT IN LINGERING MVFR CONDITIONS THROUGH
MUCH OF THE NIGHT. &&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT SAT MAY 18 2013
HEADING THRU EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE UPPER
LAKES WILL SLOWLY TIGHTEN BETWEEN LOW PRESSURE SLOWLY MOVING FROM
THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRESSURE
BUILDING IN THE VICINITY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING TO ALMOST 30 KNOTS BY MON AND
MON NIGHT...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...07
AVIATION...JLA
MARINE...07
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
511 AM EDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM EDT SAT MAY 18 2013
IN THE LARGE SCALE...TROUGH OVER THE ROCKIES WILL SLIDE ONTO THE
HIGH PLAINS BY SUNDAY MORNING ALLOWING RIDGING TO SLIGHTLY BUILD
OVER THE WESTERN GREAT LAKES. ALTHOUGH SFC-H85 TROUGHING OVER THE
DAKOTAS DOES NOT MOVE MUCH TO THE EAST...IT IS ENOUGH TO INCREASE
LOW-LEVEL SOUTHERLY FLOW ACROSS THE UPPER GREAT LAKES. PATTERN IS
SERVING TO INCREASE MOISTURE /PWATS 1.15 OF 1.31 INCHES AT GRB AND
MPX OR AROUND 200 PCT OF NORMAL/ IN WAKE OF DRY SFC HIGH THAT HAS
BEEN ESTABLISHED OVER THE AREA FOR MOST OF THIS WEEK. REGIONAL RADAR
SHOWS DECAYING ECHOES OVER NORTHERN WISCONSIN. MUCH MORE ORGANIZED
AREA OF SHRA/TSRA HAVE DEVELOPED SINCE 03Z FROM CENTRAL MINNESOTA
INTO WEST CENTRAL WISCONSIN ALONG H85 WARM FRONT/GRADIENT OF H85
THETA-E. ADDITIONAL AREA OF SHRA/TSRA SPREADING ACROSS NORTHEAST
SOUTH DAKOTA INTO SOUTHEAST NORTH DAKOTA NEAR CONVECTIVE INDUCED
SHORTAVE/H7-H3 DIFFERENTIAL PVA AND CLOSE TO H7 MOISTURE TRANSPORT.
JUST RECENTLY ANOTHER LARGE CLUSTER OF SHRA/TSRA HAVE FORMED IN THE
WARM AIR ADVECTION REGIME BTWN THESE TWO INITIAL AREAS OF PRECIP.
GIVEN EXTENT OF SHRA/TSRA UPSTREAM OF CWA THIS MORNING AND SINCE
H85-H7 MOISTURE ADVECTION IS FORECAST WEST TO EAST ACROSS CWA
THROUGH THE DAY...INCREASED POPS FOR MOST OF THE WEST AND NORTHERN
CWA AS AT LEAST MULTIPLE REMNANTS OF THIS CONVECTION SHOULD MAKE IT
INTO UPR MICHIGAN. LEANED ON THE NCEP WRF MODELS AND RECENT HRRR AND
EXTRAPOLATION OF LATEST HRRR TO CREATE POPS. RESULT IS LIKELY POPS
MOST OF THE DAY OVER THE WEST HALF...WITH SMALLER CHANCES FARTHER
EAST AS THE RAIN RUNS INTO THE VERY DRY AIRMASS ASSOCIATED WITH SFC
HIGH TO THE EAST. MAJORITY OF TSRA THUS FAR STAYING OVER NORTHERN
MINNESOTA ON GRADIENT OF 1-6KM MUCAPE RESERVOIR. HINT IN MODELS
THAT EASTERN EDGE OF INSTABILITY GRADIENT SLIDES TOWARD WESTERN UPR
MICHIGAN SO HAVE INCLUDED SLIGHT CHANCES FOR TSRA. CONVECTION IS
ELEVATED AND MID-LEVEL LAPSE RATES BARELY GET ABOVE 6C/KM. MAIN
ISSUE WILL BE HEAVY DOWNPOURS AND LIGHTNING STRIKES. TEMPS TODAY
A BIT TOUGH TO FIGURE OUT. EAST GRADIENT WINDS SHOULD KEEP KEWEENAW
CHILLY WITH READINGS STAYING BLO 50 DEGREES. MIXING TO H9 IS PROBABLY
IT WHERE CLOUDS/RAIN PERSIST MOST OF THE DAY. THIS SUPPORTS MAJORITY
OF CWA SEEING HIGHS IN THE 60S...EVENTUALLY...ONCE THE STEADIER RAIN
TAPERS OFF THIS AFTN. SFC WARM FRONT MAY TRY TO POKE INTO FAR SW CWA
LATE IN THE DAY. IF THIS OCCURS AND PRECIP TAPERS OFF/ENDS...THEN
THERE IS POTENTIAL FOR HIGHS TO PUSH WELL INTO THE 70S FROM IWD TO
IMT.
H85 FRONT LIFTS NORTH OF MOST CWA THIS EVENING. KEWEENAW STILL CLOSE
ENOUGH TO FRONT AND WITHIN THE RIBBON OF PERSISTENT MOISTURE
ADVECTION SO KEPT SHRA/ISOLD TSRA THERE THROUGH THE EVENING. DRYING
TREND TAKES HOLD OVERNIGHT AS THE FOCUS FOR SHRA/TSRA...H85 WARM
FRONT AND THETA-E GRADIENT...LIFTS WELL TO NORTH OF UPR MICHIGAN.
KEPT SMALL POPS IN AT ISLE ROYALE LATE TONIGHT THOUGH. TEMPS MOSTLY
IN THE 40S EAST WITH FLOW OFF LK MICHIGAN. LESS MODIFIED AIR FARTHER
WEST ALLOWS MINS TO ONLY FALL INTO THE LOW-MID 50S ALONG LK SUPERIOR
AROUND IWD TO ONTONAGON AND EAST TO BARAGA/L`ANSE AND MARQUETTE
AREAS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 510 AM EDT SAT MAY 18 2013
NAM SHOWS THE 500 MB RIDGE OVER THE EASTERN U.S. 12Z SUN WITH
TROUGHING IN THE ROCKIES. THE TROUGH MOVES EAST ON SUNDAY AND PUSHES
THE RIDGE INTO THE LOWER GREAT LAKES 12Z MON WHERE THE MOVEMENT
EASTWARD STOPS THROUGH 12Z TUE. NAM HAS SOME DEEPER MOISTURE AND
850-500 MB Q-VECTOR CONVERGENCE OVER THE AREA 12Z SUN ONWARD. GFS
SHOWS ABOUT THE SAME THING AS WELL.
THIS PERIOD LOOKS PRETTY WET STARTING WITH SUN AFTERNOON THROUGH MON
NIGHT. WITH SLOW MOVEMENT OF SYSTEM INTO AND THROUGH THE AREA AND
ALSO A WARM FRONT NEAR AND TO THE SOUTH OF THE AREA...THIS SETS UP
THE CWA FOR A WIDESPREAD AND LONG LIVED RAIN EVENT WITH SOME HEAVY
RAIN POSSIBLE. AM FORECASTING ANYWHERE FROM .67 INCH OF QPF OVER THE
SOUTH...TO 1.15 INCHES OVER THE EAST TO OVER 2 INCHES OF RAIN IN THE
FAR WEST NEAR IRONWOOD FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT
AND THIS DOES NOT SEEM UNREASONABLE WITH PLENTY OF MOISTURE TO THE
SOUTH OF THE AREA AND SLOW SYSTEM MOVEMENT. FOR THIS REASON...BUMPED
POPS UP A BIT TO LIKELY TO CATEGORICAL FOR MOST OF THE CWA THROUGH
THEN. SHOULD SEE SOME SUNSHINE ON SUNDAY. MADE A FEW ADJUSTMENTS TO
TEMPERATURES BASED ON LAKE BREEZES AND WIND DIRECTIONS AND LOWERED
THEM A BIT NEAR THE GREAT LAKES SHORELINES. OTHER THAN THAT...NO
REAL BIG CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER.
IN THE EXTENDED...GFS AND ECMWF SHOW A 500 MB CLOSED LOW AND TROUGH
IN THE NORTHERN AND CENTRAL PLAINS 12Z TUE WHICH MOVE LITTLE INTO
12Z WED. BY 12Z THU...THE TROUGH AND LOW GET PUSHED A BIT FURTHER
EAST TO THE UPPER GREAT LAKES REGION. THE TROUGH AND LOW MOVE
THROUGH BY 12Z FRI WITH RIDGING BUILDING INTO THE PLAINS LATE ON
FRI. SYSTEM WILL BE SLOW TO MOVE THROUGH THE AREA...SO A COUPLE OF
DAYS OF WIDESPREAD RAIN ARE NOT OUT OF THE QUESTION ALONG WITH
COOLER TEMPERATURES WITH GRADUAL SOUTHWARD MOVEMENT OF THE SYSTEM
AWAY FROM THE AREA. THU INTO FRI...THINGS START TO DRY OUT WITH A
COLD FRONT WELL SOUTH OF THE AREA. TEMPERATURES SLIP TO SLIGHTLY
BELOW NORMAL THIS PERIOD. POPS WILL BE HIGHEST IN THE SOUTH CLOSER
TO A WARM FRONT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 141 AM EDT SAT MAY 18 2013
EXPECT VFR CONDITIONS/DRY WX TO PERSIST EARLY IN THE TAF PERIOD. BUT
AS A WARM FNT MOVES IN FM THE S...SOME -SHRA/MVFR CIGS WL BE PSBL...
MAINLY AT CMX/IWD WHERE LLVL WARM/MOIST ADVCTN WL BE MOST
PRONOUNCED. FOLLOWING THE WARM FROPA BY THIS AFTN...EXPECT WSHFT TO
THE S AND A RETURN TO PREDOMINANT VFR WX WITH DAYTIME HEATING/
MIXING. THE ONLY EXCEPTION WL BE AT CMX...WHERE A PERSISTENT UPSLOPE
ESE WIND AND MOISTER LLVL AIR WL RESULT IN LINGERING MVFR CONDITIONS.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 510 AM EDT SAT MAY 18 2013
HEADING THRU EARLY NEXT WEEK...THE PRESSURE GRADIENT OVER THE UPPER
LAKES WILL SLOWLY TIGHTEN BETWEEN LOW PRESSURE SLOWLY MOVING FROM
THE WRN PLAINS TOWARD THE UPPER MISSISSIPPI VALLEY AND HIGH PRESSURE
BUILDING IN THE VICINITY OF WRN HUDSON BAY. THIS WILL LEAD TO
EASTERLY WINDS GRADUALLY INCREASING TO ALMOST 30 KNOTS BY MON AND
MON NIGHT...ESPECIALLY OVER WRN LAKE SUPERIOR WHERE
FUNNELING/CHANNELING WILL ENHANCE THE WINDS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLA
LONG TERM...07
AVIATION...KC
MARINE...07
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1041 PM CDT SUN MAY 19 2013
.UPDATE...
FOR 06Z AVIATION DISCUSSION BELOW
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013
NARROW AREA OF MODERATE TO STRONG THUNDERSTORMS NOTED ON RADAR
FROM TWIN CITIES SOUTH INTO EASTERN FREEBORN COUNTY. HRRR HANDLED
INTIATION OF THIS ACTIVITY OVER FAR NORTHERN IOWA AND FAR SOUTH
CENTRAL MN VERY WELL EARLIER THIS AFTERNOON...SO USED SAME TO
HELP PROJECT CONVECTION INTO TONIGHT ACROSS MUCH OF THE CWA.
USED GFS40 THETA E ADVECTION TO SORT OUT TIMING AND INTENSITY
OF PCPN INTO MONDAY AFTERNOON. THROTTLED BACK SOMEWHAT ON
QPF VALUES OVER PORTION OF THE FA DUE TO SLACKENING POP CHANCES
LATER TONIGHT AND AGAIN ON MONDAY. LOCAL WRF MODEL STILL INDICATING
VERY IMPRESSIVE 850MB TRANSPORT VECTOR CONVERGENCE OVER MUCH OF
THE FA LATE THIS AFTN INTO THIS EVENING...WITH SLACKENING VALUES
NOTED OVER SW PORTION OF CWA BY 06Z. WITH THAT SAID ANTICIPATE
BEST CHANCES FOR ANY FLOOD POTENTIAL FOR REMAINDER OF FLASH
FLOOD WATCH REGION WILL BE EAST OF A LINE...FROM ST CLOUD TO
HUTCHINSON...TO WINNEBAGO. 50H LOW OVER WESTERN DAKOTAS WILL
BECOME VERTICALLY STACKED WITH SFC CYCLONE BY MON/12Z TIME FRAME
ABOVE SE SODAK. SYSTEM WILL RETROGRADE INTO SE NODAK BY EARLY
MONDAY EVENING. BEST CHANCES FOR POPS CLEARLY INDICATED OVER
NORTHERN HALF OF FA MONDAY AFTN...IN ASSOCIATION WITH BEST
THETA E ADVECTION COUPLED WITH POSITION OF RIGHT REAR QUAD RELATED
TO 130KT JET CORE ABOVE NORTHERN ONTARIO.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 355 PM CDT SUN MAY 19 2013
BRIEF DISCUSSION DUE TO ONGOING STORMS. STUBBORN LOW PRESSURE SYSTEM
IN SOUTH DAKOTA LOOKS LIKE IT WILL DRIFT EAST...STILL OVER MN ON
WEDNESDAY. TROUGH AXIS SWINGS BY TO THE SOUTH EARLY WEDNESDAY...AND
HAVE THUS ENDED MENTION OF STORMS TUESDAY NIGHT. WILL KEEP MENTION
OF SHOWERS WEDNESDAY AND WED NIGHT. MOSTLY CLOUDY AND COOL WEATHER
EXPECTED AND HAVE LOWERED MAX TEMPS. UPPER LOW STILL CLOSE ENOUGH TO
MERIT KEEPING A CHANCE OF SHOWERS INTO THURSDAY IN THE EAST. THEN
UPPER RIDGE APPROACHES. CANADIAN SURFACE HIGH MAKES A GLANCING BLOW
AND WINDS MAY BE LIGHT ENOUGH THURSDAY NIGHT TO ALLOW TEMPS TO DROP
INTO THE UPPER 30S FROM MILLE LACS LAKE TO RICE LAKE AND LADYSMITH.
SOME VARIATION IN MODELS AS TO HOW LONG THE UPPER RIDGE WILL REMAIN
OVER THE AREA LATE THIS WEEK. SOME GUIDANCE SUGGESTS IT MOVING EAST
QUICKLY ENOUGH TO BRING IN ANOTHER CHANCE OF STORMS SATURDAY AND
SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1042 PM CDT SUN MAY 19 2013
THE AREA OF SHOWERS AND THUNDERSTORMS OVER SOUTHEASTERN MN AND
WEST CENTRAL WI WILL GRADUALLY FILL BACK IN TO THE NORTH AND WEST
ACROSS CENTRAL MN OVERNIGHT...WHICH IS ILLUSTRATED BY THE HRRR
MODEL. MVFR CIGS/VSBYS IN THE SHRA ARE EXPECTED...ALONG WITH IFR
CIGS FROM KSTC-KAXN. AFTER 15Z MONDAY...EXPECT A LULL IN
CONVECTION UNTIL DAYTIME HEATING CAUSES THE NEXT ROUND OF
POTENTIALLY STRONG TO SEVERE THUNDERSTORMS TO DEVELOP. WINDS WILL
BE SOUTHEASTERLY AOB 10 KTS OVERNIGHT...THEN BECOME GUSTY BY LATE
MORNING MONDAY AND VEER SLIGHTLY TO MORE SOUTH/SOUTHWESTERLY IN
DIRECTION.
KMSP...
EXPECT THE SHOWERS OVER SOUTHEASTERN MN TO GRADUALLY EXPAND BACK
WEST/NORTHWEST AT THE START OF THE PERIOD...THEN TAPER OFF BY 14Z
MONDAY WHEN WINDS BECOME GUSTY. CIGS MAY DIP TO 1500 FT OVERNIGHT
WITH THE SHOWER ACTIVITY...BUT THE PREVALENT CIG SHOULD BE
2500-3500FT. SOUTHEAST WINDS AROUND 150 DEGREES BEGIN GUSTING TO
25 KTS BY 15Z...THEN VEER TO AROUND 200 DEGREES BY 18Z WITH GUSTS
CONTINUING.
/OUTLOOK FOR KMSP/
TUE...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S-SW WIND 5 KTS.
WED...VFR/MVFR CIGS. SHRA LIKELY. NE WIND 5-10 KTS.
THU...VFR. NE WINDS 10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ041>045-047>053-
057>063-066>070-075>078-084-085-093.
WI...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR WIZ014>016-023>028.
&&
$$
SHORT TERM...AJZ
LONG TERM...TDK
AVIATION...LS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
654 PM CDT SUN MAY 19 2013
.UPDATE...
FOR 00Z AVIATION DISCUSSION BELOW
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013
NARROW AREA OF MODERATE TO STRONG THUNDERSTORMS NOTED ON RADAR
FROM TWIN CITIES SOUTH INTO EASTERN FREEBORN COUNTY. HRRR HANDLED
INTIATION OF THIS ACTIVITY OVER FAR NORTHERN IOWA AND FAR SOUTH
CENTRAL MN VERY WELL EARLIER THIS AFTERNOON...SO USED SAME TO
HELP PROJECT CONVECTION INTO TONIGHT ACROSS MUCH OF THE CWA.
USED GFS40 THETA E ADVECTION TO SORT OUT TIMING AND INTENSITY
OF PCPN INTO MONDAY AFTERNOON. THROTTLED BACK SOMEWHAT ON
QPF VALUES OVER PORTION OF THE FA DUE TO SLACKENING POP CHANCES
LATER TONIGHT AND AGAIN ON MONDAY. LOCAL WRF MODEL STILL INDICATING
VERY IMPRESSIVE 850MB TRANSPORT VECTOR CONVERGENCE OVER MUCH OF
THE FA LATE THIS AFTN INTO THIS EVENING...WITH SLACKENING VALUES
NOTED OVER SW PORTION OF CWA BY 06Z. WITH THAT SAID ANTICIPATE
BEST CHANCES FOR ANY FLOOD POTENTIAL FOR REMAINDER OF FLASH
FLOOD WATCH REGION WILL BE EAST OF A LINE...FROM ST CLOUD TO
HUTCHINSON...TO WINNEBAGO. 50H LOW OVER WESTERN DAKOTAS WILL
BECOME VERTICALLY STACKED WITH SFC CYCLONE BY MON/12Z TIME FRAME
ABOVE SE SODAK. SYSTEM WILL RETROGRADE INTO SE NODAK BY EARLY
MONDAY EVENING. BEST CHANCES FOR POPS CLEARLY INDICATED OVER
NORTHERN HALF OF FA MONDAY AFTN...IN ASSOCIATION WITH BEST
THETA E ADVECTION COUPLED WITH POSITION OF RIGHT REAR QUAD RELATED
TO 130KT JET CORE ABOVE NORTHERN ONTARIO.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 355 PM CDT SUN MAY 19 2013
BRIEF DISCUSSION DUE TO ONGOING STORMS. STUBBORN LOW PRESSURE SYSTEM
IN SOUTH DAKOTA LOOKS LIKE IT WILL DRIFT EAST...STILL OVER MN ON
WEDNESDAY. TROUGH AXIS SWINGS BY TO THE SOUTH EARLY WEDNESDAY...AND
HAVE THUS ENDED MENTION OF STORMS TUESDAY NIGHT. WILL KEEP MENTION
OF SHOWERS WEDNESDAY AND WED NIGHT. MOSTLY CLOUDY AND COOL WEATHER
EXPECTED AND HAVE LOWERED MAX TEMPS. UPPER LOW STILL CLOSE ENOUGH TO
MERIT KEEPING A CHANCE OF SHOWERS INTO THURSDAY IN THE EAST. THEN
UPPER RIDGE APPROACHES. CANADIAN SURFACE HIGH MAKES A GLANCING BLOW
AND WINDS MAY BE LIGHT ENOUGH THURSDAY NIGHT TO ALLOW TEMPS TO DROP
INTO THE UPPER 30S FROM MILLE LACS LAKE TO RICE LAKE AND LADYSMITH.
SOME VARIATION IN MODELS AS TO HOW LONG THE UPPER RIDGE WILL REMAIN
OVER THE AREA LATE THIS WEEK. SOME GUIDANCE SUGGESTS IT MOVING EAST
QUICKLY ENOUGH TO BRING IN ANOTHER CHANCE OF STORMS SATURDAY AND
SUNDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 653 PM CDT SUN MAY 19 2013
CONVECTIVE COMPLEX OF SHOWERS AND THUNDERSTORMS WILL MAINLY AFFECT
NORTHERN/EASTERN TAF SITES THIS EVENING /KAXN-KSTC-KEAU/...WITH
COVERAGE BECOMING MORE WORTHY ONLY OF A VICINITY MENTION AFTER
02Z. COULD BE SCATTERED SHOWERS AND THUNDERSTORMS AROUND THROUGH
TONIGHT AS THE UPPER LOW ROTATES INTO THE AREA. AFTER SUNSET THIS
EVENING HOWEVER...THE STRONG STORMS SHOULD HOLD OFF UNTIL DIURNAL
DESTABILIZATION OCCURS AFTER 17Z MONDAY. LOOKING LIKE ANOTHER
AFTERNOON WITH A DECENT RISK OF SEVERE THUNDERSTORMS. WINDS WILL
PRIMARILY BE SOUTHEASTERLY THROUGH MONDAY MORNING...WITH GUSTS TO
BETWEEN 20 AND 25 KTS DEVELOPING BY 17Z MONDAY. THE DIRECTIONAL
COMPONENT WILL BECOME MORE SOUTH-SOUTHWESTERLY MONDAY AFTERNOON
AS THE SURFACE LOW APPROACHES.
KMSP...
THERE WILL BE A SHORT BREAK IN THE SHOWER/THUNDERSTORM ACTIVITY
THROUGH SUNSET...AND THEN WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE FROM AROUND 02Z THROUGH 09Z. AFTER
THE NOCTURNAL ACTIVITY...THERE SHOULD BE A BREAK UNTIL DIURNAL
HEATING AIDS IN THUNDERSTORM DEVELOPMENT ON MONDAY AFTERNOON. CIGS
SHOULD BE MOSTLY VFR WITH THE EXCEPTION OF MVFR IN SHRA.
/OUTLOOK FOR KMSP/
MON...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S-SSE WIND 10-15 G 25 KTS.
TUE...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S-SW WIND 5 KTS.
WED...VFR/MVFR CIGS. SHRA LIKELY. NE WIND 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ041>045-047>053-
057>063-066>070-075>078-084-085-093.
WI...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR WIZ014>016-023>028.
&&
$$
SHORT TERM...AJZ
LONG TERM...TDK
AVIATION...LS
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
314 PM CDT SAT MAY 18 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 312 PM CDT SAT MAY 18 2013
(TONIGHT)
THE PRIMARY CONCERN TONIGHT IS POTENTIAL THUNDERSTORM DEVELOPMENT
NORTH OF A NW-SE ORIENTED WARM FRONT THAT WILL LIFT ACROSS THE CWA
OVERNIGHT. GIVEN THE UNSTABLE AIRMASS IN PLACE OVER THE REGION
/MUCAPES ON THE ORDER OF 2500-3000J/KG AS PER THE RUC...GFS...AND
LOCAL WRF MODELS FOR TONIGHT/ ADDITIONAL WAA AND A VEERING LLJ COULD
CERTAINLY PROVIDE ENOUGH LIFT TO FIRE SOME STORMS DURING THE LATE
OVERNIGHT AND EARLY MORNING HOURS. THE 4KM WRF-NNM AND HRRR DEVELOP
SCATTERED STORMS TONIGHT NORTH OF THE FRONT...PARTICULARLY THROUGH
THE 09Z-12Z TIME FRAME. THUS...HAVE MAINTAINED TRENDS IN TONIGHT`S
FORECAST...INTRODUCING SCHC POPS AFTER MIDNIGHT WITH A FOCUSED AREA
OF CHC POPS MARCHING NORTHWARD THROUGH THE LATE OVERNIGHT HOURS AND
TOWARD DAYBREAK.
OTHERWISE...ANOTHER WARM NIGHT IS AHEAD FOR THE AREA...WITH LOW
TEMPERATURES EXPECTED TO DROP INTO THE MIDDLE 60S FOR SOUTHWEST
ILLINOIS TO UPPER 60S OVER MID MISSOURI AND FOR THE STL METRO AREA.
JP
.LONG TERM...(SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
ON SUNDAY...WARM FRONT TO LIFT NORTH OF FORECAST AREA BY
MIDDAY...SO JUST HAVE SLIGHT CHANCE POPS DURING THE MORNING
HOURS...THEN BEST CHANCES OF STORMS IN CENTRAL/NORTHEAST MO...WEST
CENTRAL IL DURING THE AFTERNOON HOURS CLOSER TO THE MAIN WEATHER
SYSTEM. THE ACTIVITY RAMPS UP DURING SUNDAY EVENING AND THE
OVERNIGHT HOURS AS A SHORTWAVE ROTATES AROUND THE UPPER SYSTEM
THROUGH THE FORECAST AREA...THOUGH BEST CHANCES REMAIN OVER
CENTRAL/NORTHEAST MO...WEST CENTRAL IL ON NOSE OF LOW LEVEL JET.
WITH DECENT SHEAR AND INSTABILITY...AS WELL AS LOW LEVEL
MOISTURE...SEVERE STORMS ARE POSSIBLE OVER THIS AREA...WITH THE
MAIN THREAT BEING LARGE HAIL. OTHERWISE...WITH WARM FRONT LIFTING
NORTH OF FORECAST AREA AND 850 TEMPS APPROACHING 20C...WILL SEE
TEMPS WARM UP INTO THE MID TO UPPER 80S. LOWS SUNDAY NIGHT TO
REMAIN MILD...IN THE MID TO UPPER 60S.
ON MONDAY...ACTIVITY TO TAPER OFF A BIT...BEFORE RAMPING BACK UP
LATE MONDAY AFTERNOON AND THROUGH THE OVERNIGHT HOURS WITH NEXT
SIGNIFICANT SHORTWAVE AND ANOTHER ROUND OF SEVERE WEATHER POSSIBLE.
WITH MODELS CONTINUING TO SLOW DOWN THIS SYSTEM...WILL SEE THE
STORMS PERSIST THROUGH WEDNESDAY BEFORE TAPERING OFF AS FRONTAL
BOUNDARY FINALLY MOVES THROUGH. TEMPERATURES TO REMAIN ABOVE NORMAL
THROUGH THE FIRST PART OF THE WORK WEEK...BEFORE COOLING OFF TO NEAR
NORMAL TEMPS IN THE 70S FOR THE LAST HALF OF THE WORK WEEK.
WITH SLOW EXIT OF SYSTEM AND FRONTAL BOUNDARY STALLED OUT JUST SOUTH
OF FORECAST AREA ON THURSDAY...CHANCE POPS OVER SOUTHEAST HALF OF
FORECAST AREA STILL LOOKS GOOD. OTHERWISE...DRY WEATHER EXPECTED
FRIDAY AND SATURDAY.
BYRD
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1243 PM CDT SAT MAY 18 2013
FOG HAS DISSIPATED ACROSS THE REGION...THOUGH CIGS HAVE BEEN A BIT
SLOW TO RECOVER...PARTICULARLY ACROSS NORTHEAST MO AND OVER THE
OZARKS. LATEST VISIBLE SATELLITE IMAGERY SHOWS AN EXTENSIVE
CUMULUS FIELD DEVELOPING OVER THE MISSISSIPPI VALLEY...THOUGH
EXPECT THE GRADUAL IMPROVEMENT IN CIGS TO CONTINUE THIS
AFTERNOON...WITH JUST SOME SCT VFR CLOUDS EXPECTED.
A NW-SE ORIENTED WARM FRONT WILL SHIFT NORTHWARD ACROSS THE REGION
OVERNIGHT TONIGHT...AND MODELS CONTINUE TO INDICATE THE
DEVELOPMENT OF SOME SHRA/TSRA ALONG AND AHEAD OF THE ADVANCING
WARM FRONT. FOR NOW...HAVE INCLUDED MENTION OF VCSH FOR AREA TAF
SITES DURING THE EARLY MORNING HOURS...AND WILL DEFER TO LATER TAF
ISSUANCES TO FURTHER PIN DOWN TIMING AND/OR MENTION OF TSRA.
OTHERWISE...WINDS WILL REMAIN SOUTHEASTERLY TODAY AND VEER TO
THE SOUTH ON SUNDAY...INCREASING TO ABOUT 10-12KT WITH SOME GUSTS
AS RETURN FLOW SETS IN.
SPECIFICS FOR KSTL...
CIGS ARE EXPECTED TO CONTINUE TO IMPROVE TO SCT VFR THIS
AFTERNOON...WITH LIGHT SOUTHEAST WINDS. OVERNIGHT TONIGHT A WARM
FRONT WILL DRIFT NORTH ACROSS THE AREA...AND MODELS CONTINUE TO
INDICATE SOME SHRA/TSRA DEVELOPMENT ACCOMPANYING THE FRONT. HAVE
CURRENTLY INCLUDED VCSH MENTION FOR KSTL FROM 10-13Z...THOUGH
TIMING WILL LIKELY NEED REFINED IN LATER TAF ISSUANCES...ALONG
WITH POTENTIAL THUNDER MENTION WHEN COVERAGE/INTENSITY BECOMES
MORE CLEAR. WINDS WILL VEER TO THE SOUTH TOMORROW BEHIND THE
ADVANCING WARM FRONT...INCREASING TO 10-12KT AND GUSTING TO
20-22KT BY THE AFTERNOON.
JP
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS GLASGOW MT
911 PM MDT SUN MAY 19 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
UPDATE...
CONVECTIVE SHOWER ACTIVITY IS BEGINNING TO FADE AS IT PUSHES OUT
OF PHILLIPS AND PETROLEUM COUNTIES. WILL GO AHEAD AND REDUCE POPS
A BIT TO ACCOUNT FOR THIS. A SURFACE LOW PRESSURE IS SENDING A
RETROGRADING SHIELD OF STRATIFORM RAIN INTO THE CWA FROM EAST TO
WEST AS IT BECOMES VERTICALLY STACKED OVER THE DAKOTAS. MAIN
FORECAST CHALLENGE WILL BE FINAL RAINFALL AMOUNTS...AND THE FINAL
WESTERN EXTENT OF THE RAIN AS IT PUSHES INTO THE FORECAST REGION.
THE LATEST NAM AND ECMWF APPEARS TO BE TOO SLOW WITH THE
RETROGRADING RAIN SHIELD. THE HRRR SOLUTION SEEMS TO BE A BIT TOO
BULLISH WITH PRECIPITATION IN SOME OF THE CENTRAL ZONES. THE GFS
IS FAIRLY CLOSE IN LINE WITH THE INITIAL LOCATION OF THE WESTERN
EDGE OF THE STRATIFORM RAIN AND THEREFORE HAVE PLACED A LITTLE
MORE WEIGHT ON THAT SOLUTION. BELIEVE THAT OVERNIGHT THE BACK
EXTENT OF THE RAIN WILL REACH A LINE EXTENDING FROM ABOUT JUST
EAST OF OPHEIM...THROUGH GLASGOW...AND INTO WESTERN GARFIELD
COUNTY. WILL TAKE A LOOK AT THE OOZ MODEL SUITE AS IT CONTINUES TO
COME IN AND MAKE ANY NEEDED ADJUSTMENTS FOR THE MORNING PACKAGE.
THE OTHER CONSIDERATION WILL BE SURFACE WIND SPEEDS TOMORROW WITH
THE PRESENCE OF A PRETTY TIGHT PRESSURE GRADIENT OVER ESPECIALLY
THE EASTERN HALF OF THE CWA. NOT SURE IF A LAKE WIND ADVISORY WILL
BE NECESSARY AS IT LOOKS FAIRLY MARGINAL. MALIAWCO
PREVIOUS SHORT TERM DISCUSSION...
THE LOW PRESSURE CENTERS ARE CLOSING OFF AND BEGINNING TO STACK
OVER THE DAKOTAS. THE FOCUS OF PRECIPITATION IS WHERE THE INVERTED
SURFACE TROUGH NUDGES INTO THE WESTERN DAKOTAS AND EASTERN
COUNTIES OF NORTHEAST MONTANA. A BIT OF DRY SLOTTING INITIALLY
THROUGH THE CENTRAL COUNTIES OF NORTHEAST MONTANA...THEN THE
WESTERN COUNTIES AFTER MIDNIGHT WILL DIMINISH CHANCES THERE OF ANY
MEANINGFUL PRECIPITATION. EXPECT WIND TO PICK UP...MAINLY IN THE
EAST...AS THE SURFACE LOW RETROGRADES BACK TOWARDS OUR CWA.
MONDAY...THE WRAP-AROUND PRECIPITATION CONTINUES ON THE HEAVY
SIDE IN THE MORNING...BUT FINALLY AS THE LOW MOVES FARTHER EAST
THE INVERTED SURFACE TROUGH IS PULLED AWAY AND RAIN INTENSITY
DIMINISHES DURING THE AFTERNOON...BUT SHOULD CONTINUE MONDAY
NIGHT IN THE EAST. THE LOW MOVING AWAY WILL ALSO LIGHTEN THE WIND
IN THE WEST. BUT WIND IN THE EAST WILL BECOME STRONG FROM THE
NORTH DUE TO THE NEARNESS OF THE SURFACE LOW AND WIND ALOFT THAT
LINES UP. THIS WIND COULD EDGE FAR ENOUGH WEST FOR THE NEED OF A
WIND ADVISORY FOR THE EASTERN END OF FORT PECK LAKE. WILL TURN
THAT OVER TO THE OVERNIGHT SHIFT FOR ANOTHER LOOK. THERE COULD BE
SOME CLEARING IN THE NORTHWEST LATE THIS AFTERNOON AND EVENING.
TUESDAY...THE INFLUENCE OF THE LOW WILL BE TENACIOUS IN ITS REACH
INTO THE EASTERN COUNTIES OF NORTHEAST MONTANA QPF WILL LIGHT BUT
LOW OVERCAST CONTINUES. FOR THE WESTERN COUNTIES CONDITIONS WILL
BE INFLUENCED BY WEAK RIDGING BETWEEN THE DEPARTING LOW AND THE
NEXT STRONG LOW BUMPING UP AGAINST THE WASHINGTON/OREGON COAST.
TEMPERATURE DURING THE SHORT TERM WILL BE MILD AND VERY NEAR
NORMAL FOR THIS TIME OF YEAR. TEMPERATURES WILL TEND TO PUT A LID
ON THUNDERSTORM ACTIVITY...BUT WILL LEAVE ISOLATED TS IN DURING
THIS EVENINGS IN THE WEST WHERE THERE ARE A FEW GENERAL
THUNDERSTORMS. SCT
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
UPPER LOW OVER THE NORTHERN PLAINS EXPECTED TO SLIDE EAST BY THE
BEGINNING OF THE EXTENDED PERIOD...TO BE REPLACED BY A NARROW
UPPER RIDGE AS ANOTHER CLOSED LOW SETTLES INTO THE PACIFIC
NORTHWEST. NORTHEAST MONTANA WILL BE IN THE BOUNDARY AREA WHERE
THE SOUTHWEST FLOW AROUND THE BASE OF THE LOW MEETS THE UPPER
RIDGE. MAIN CHANCE OF RAIN WILL BE ACROSS THE WESTERN ZONES
THROUGH MIDWEEK THEN SPREAD EAST INTO THE WEEKEND AS THE MODELS
BEGIN TO OPEN UP THE LOW. EBERT
PREVIOUS LONG TERM DISCUSSION...THE EXTENDED PERIOD CONTINUES WITH
UPPER LOWS TO OUR WEST AND EAST AND CONFUSED FLOW OVER NORTHEAST
MONTANA. THIS WILL CONTINUE UNTIL FRIDAY WHEN THE UPPER LOW IN THE
PACIFIC NORTHWEST SHIFTS CLOSER TO NORTHEAST MONTANA. THIS WILL
ENHANCE THE POSSIBILITY OF THUNDERSTORMS OVER THE WEEKEND.
TEMPERATURES WILL CONTINUE AROUND NORMAL WITH HIGHS HOVERING
AROUND 70 AND LOWS IN THE UPPER 40S TO LOWER 50S THROUGH THE PERIOD.
MODEL TRENDS SHOW A FAIRLY SMOOTH RUN TO RUN PERFORMANCE WHICH
ASSISTS WITH A HIGH CONFIDENCE. DID NOT GO TOO HIGH FOR POPS OVER
THE UPCOMING WEEKEND SINCE THERE IS A HINT OF RETROGRESSION
STARTING TO SHOW UP WITH FALLING HEIGHTS IN MOST ENSEMBLES OVER
THE NORTHEAST PACIFIC. THIS COULD LEAD TO THE UPPER LOW SINKING
FURTHER SOUTH AND WEST KEEPING NORTHEAST MONTANA DRIER. OVERALL
ENSEMBLES ARE FAIRLY GOOD SINCE WE ARE IN A CLIMATOLOGICAL NORMAL
PATTERN. RMOP ARE FAIRLY GOOD WITH THE LARGE SCALE FEATURES FOR
THE EXTENDED PERIOD. THEREFORE MODERATE TO GOOD CONFIDENCE IN THE
PERIOD FROM TUESDAY NIGHT THROUGH FRIDAY WITH SOME LOWER
CONFIDENCE IN THE WEEKEND PATTERN. PROTON
&&
.AVIATION...
VFR BECOMING MVFR OVERNIGHT AS RAIN RETURNS TO THE REGION FROM THE
EAST...SLIGHTLY WORSE CONDITIONS AT KSDY WITH HEAVIER RAIN
EXPECTED. CIGS WILL BE CLOSE TO IFR AT TIMES LATE TONIGHT/EARLY
MONDAY AT ESPECIALLY KSDY AND KGDV. GUSTY NORTH WINDS ALSO
EXPECTED TO PERSIST THROUGH MONDAY MORNING. JAMBA
&&
.HYDROLOGY...
THE NEXT COUPLE OF DAYS WILL BE RATHER WET AS AN UPPER-LEVEL
TROUGH AFFECTS THE REGION. SEVERAL DISTURBANCES ASSOCIATED WITH THIS
TROUGH WILL PASS THROUGH WHICH WILL KEEP CHANCES FOR RAIN THROUGH
TUESDAY. MODEL GUIDANCE DEPICTS HIGH AMOUNTS OF MOISTURE WITH THIS
SYSTEM. AT THIS POINT THE ENVIRONMENT LOOKS FAVORABLE FOR SLOW-
MOVING STORMS WITH HIGHER PRECIPITATION IN LOCALIZED AREAS.
MOST OF THE BASINS IN NORTHEAST MONTANA WILL BE ABLE TO
ACCOMMODATE THIS AMOUNT OF MOISTURE. HOWEVER THERE IS SOME
CONCERN FOR RAPIDLY RISING STREAMS...FIELD FLOODING AND LOCALIZED
FLOODING IN TOWNS AS THE EVENT PERSISTS. SOME MINOR FLOODING MAY
BECOME AN ISSUE...ESPECIALLY FOR THE AREAS FROM WOLF POINT TO
CIRCLE AND EASTWARD INTO NORTH DAKOTA WHERE THE POTENTIAL FOR RAIN
IS HIGHER.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BILLINGS MT
919 AM MDT SAT MAY 18 2013
.UPDATE...
HAVE MADE SOME CHANGES TO THE MORNING FORECAST. GFS/ECMWF/NAM12
ARE IN GOOD AGREEMENT IN LIFTING ANOTHER WAVE ACROSS THE AREA THIS
MORNING. RADAR RETURNS HAVE BEEN INCREASING OVER SOUTH CENTRAL
MONTANA THIS MORNING WITH UPPER JET BRINGING A SHORT WAVE INTO THE
AREA ALONG WITH INCREASING QG FORCING. A FEW EMBEDDED
THUNDERSHOWERS ALSO POSSIBLE WITH WEAK LOW LEVEL INSTABILITY. HAVE
RAISED POPS TO LIKELY FROM BILLINGS WEST FOR THIS MORNING. LOWERED
POPS IN THE EAST FOR THIS MORNING AS FORCING FROM THE UPPER LEVEL
TROUGH WILL NOT IMPACT SOUTHEAST MONTANA UNTIL AFTER 18Z TODAY.
PATCHY FOG ACROSS THE AREA IS QUICKLY LIFTING AND WILL REMOVE IT
FROM THE FORECAST. NO CHANGES TO TEMPERATURE FORECAST THEY LINE UP
WELL WITH CURRENT GUIDANCE. RICHMOND
&&
.SHORT TERM...VALID FOR TDY AND SUN...
RAINFALL TOTALING AN INCH OR MORE STILL LOOKS LIKE A GOOD BET OVER
THE NEXT FEW DAYS IN MANY AREAS. HOWEVER...THE 500-HPA TROUGH THAT
IS SET TO DRIVE ONE OF THE BETTER PRECIPITATION EVENTS WE HAVE HAD
IN A LONG TIME IS SURPRISING COMPLEX...SO SOME UNCERTAINTY EXISTS.
TODAY...THE MID-LEVEL SHORT WAVE TROUGH CENTERED NEAR 700 HPA THAT
IS SEEN ENTERING WESTERN WY ON 09 UTC MOISTURE CHANNEL IMAGES WILL
MOVE INTO SOUTHERN MT. THE ECMWF HAS BEEN THE MOST CONSISTENT WITH
BRINGING THIS BATCH OF FORCING INTO THE AREA IN THE LAST FEW DAYS.
ITS 00 UTC RUN CONTINUES THIS THEME...GENERATING CONVECTION ACROSS
MUCH OF THE AREA AFTER 18 UTC...WITH QPF AMOUNTS OF A QUARTER TO A
HALF INCH. THE 00 UTC GFS HAS FINALLY PICKED UP ON THIS SHORT WAVE
TOO...SO OUR CONFIDENCE IN PRECIPITATION HAS INCREASED ENOUGH THAT
WE HAVE CHOSEN TO ADVERTISE 90 TO 100 PERCENT POPS AFTER 18 UTC IN
THE BILLINGS...SHERIDAN...MILES CITY...AND BROADUS AREAS. THE 700-
500 HPA LAPSE RATES ARE MODEST AROUND 6 C/KM...BUT THERE IS ENOUGH
INSTABILITY /POCKETS OF MUCAPE UP TO 500 J/KG/ TO GENERATE THUNDER
AS WELL. CALIBRATED THUNDERSTORM PROBABILITIES OFF THE 03 UTC SREF
JUMP UP INTO THE 40 AND 50 PERCENT RANGE AFTER 18 UTC AS WELL. THE
SEVERE RISK IS NEGLIGIBLE THOUGH GIVEN THE EXPECTED INSTABILITY. A
CAUTIONARY NOTE ABOUT THE POP FORECAST IS THAT MANY WRF-BASED HIGH
RESOLUTION MODELS FROM 00 UTC CLUSTER CONVECTION FURTHER SOUTHEAST
FROM SHERIDAN TOWARD BROADUS...WHICH MAY ACTUALLY SUPPRESS SOME OF
THE PRECIPITATION FURTHER NORTH IN PLACES LIKE BILLINGS. NOTE THAT
WE ALSO DECIDED TO CARRY ONLY CHANCE POPS IN MANY PLACES BEFORE 18
UTC BASED ON UPSTREAM TRENDS AND RECENT RAP AND HRRR OUTPUT.
TONIGHT...WE CONTINUED LEANING ON THE 00 UTC ECMWF SOLUTION DURING
THE EVENING...WITH A CONCENTRATED AREA OF CATEGORICAL POPS FOR THE
PLAINS OF SOUTH CENTRAL AND SOUTHEASTERN MT BEFORE 06 UTC. WE THEN
LET POPS FALL BACK A BIT AFTER MIDNIGHT IN MANY AREAS SINCE 1/ THE
DIURNALLY-DRIVEN CONVECTION SHOULD DIMINISH WITH SUNSET...AND 2/ A
BREAK IN FORCING SHOULD TAKE PLACE AS THE 700-HPA SHORT WAVE MOVES
OUT AND/OR WEAKENS. IF THE ECMWF IS CORRECT...WE MAY ACTUALLY HAVE
A RELATIVELY DRY PERIOD AFTER 06 UTC. HOWEVER...THE 00 UTC GFS AND
EVEN THE 03 UTC SREF KEEP MORE STRATIFORM-BASED PRECIPITATION OVER
SOUTH CENTRAL MT AND NORTH CENTRAL WY RIGHT THROUGH THE NIGHT...SO
WE WERE CAUTIOUS ABOUT LOWERING POPS BELOW THE LIKELY THRESHOLD AT
THIS POINT. WE ALSO KEPT IN ISOLATED THUNDERSTORMS FOR MOST OF THE
AREA AFTER 06 UTC...BUT WE MIGHT BE ABLE TO DROP THAT MENTION WITH
LATER FORECASTS SINCE MUCAPE AND THE SREF THUNDERSTORM PROBABILITY
VALUES BOTH DWINDLE NOCTURNALLY.
ON SUN...A 500-HPA TROUGH IS EXPECTED TO CLOSE OFF...LIKELY ACROSS
WY...AND THAT SHOULD DRIVE A MORE STEADY RAIN EVENT ACROSS PART OR
EVEN ALL OF THE AREA. THIS IS THE POINT WHERE COMPLEX INTERACTIONS
OF SHORT WAVES AND CONVECTION WITHIN THE LARGER-SCALE TROUGH COULD
ULTIMATELY DICTATE WHERE AND HOW MUCH RAIN FALLS. WE INCREASED THE
POPS ONE MORE TIME THOUGH SO THAT THEY ARE CATEGORICAL FOR MUCH OF
THE AREA SINCE THERE IS FAIR AGREEMENT AMONG 00 UTC MODELS. LIKELY
AND CATEGORICAL POPS CONTINUE INTO SUN NIGHT.
HYDROLOGY-WISE...WE DECIDED TO LET GO OF THE FLASH FLOOD WATCH FOR
THE BURN SCAR AREAS WITH THIS FORECAST RELEASE. THE RAINFALL RATES
OVER THE NEXT FEW DAYS ARE NOT EXPECTED TO BE LARGE ENOUGH TO NEED
AN EXTENSION OF THE WATCH...THOUGH WE WILL CERTAINLY BE KEEPING AN
EYE ON THOSE BURN SCAR AREAS REGARDLESS. OTHERWISE...THERE WILL BE
AT LEAST MINOR RISES ON AREA RIVERS AND STREAMS IN THE COMING DAYS
IF THE FORECAST PRECIPITATION AMOUNTS COME TO FRUITION. HOWEVER...
NO FLOODING IS EXPECTED BECAUSE OUR VERY DRY SOILS WILL BE ABLE TO
EASILY ABSORB MUCH OF THE MOISTURE. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED PERIOD STARTS ON MONDAY AND MODEL DIFFERENCES MUDDY
THE WATERS ON TIMING OF PRECIPITATION TAPERING OFF OVER THE AREA.
BOTH MODELS MOVE THE UPPER LOW THAT WILL IMPACT THE AREA THIS
WEEKEND INTO EASTERN SOUTH DAKOTA BY 00Z TUESDAY. THE GFS BUILDS
THE RIDGE IN MUCH MORE AGGRESSIVELY AND SENDS WRAP AROUND ENERGY
AND MOISTURE SOUTH INTO WYOMING. THE ECMWF...HOWEVER...WAS SLOWER
WITH BUILDING HEIGHTS AND THIS ALLOWS ENERGY TO WRAP BACK INTO
EASTERN AND CENTRAL ZONES MONDAY. WILL SIDE WITH THE ECMWF AS THIS
WAS THE CONSENSUS OF SURROUNDING OFFICES AS OFTEN TIMES THESE
SLOW MOVING UPPER LOWS ARE SLOWER TO DRY OUT THAN MODELS EXPECT.
SHOULD GET DRYING CONDITIONS FOR TUESDAY AS THE RIDGE BUILDS IN
EARNEST. THE NEXT UPPER LOW...WHICH IS PROGGED TO BE QUITE A BIT
DEEPER THAN ITS PREDECESSOR...MOVES INLAND WEDNESDAY. ENERGY DOES
SWING AROUND THE UPPER LOW AND DRIVES ACROSS WESTERN AND CENTRAL
ZONES WEDNESDAY AND THURSDAY. LOW LEVEL WINDS WILL BE EASTERLY AND
THIS SHOULD ALLOW DEWPOINTS TO BE ON THE RISE. DRIER AIR WILL GET
PULLED INTO THE SYSTEM BUT THE GFS HAS BACKED OFF ON THIS FROM
YESTERDAY. CAPES SHOULD INCREASE WITH EASTERLY WINDS INCREASING
LOW LEVEL DEWPOINTS. RAISED POPS OVER WESTERN AND CENTRAL ZONES
FOR AFTERNOON AND EVENING CONVECTION WEDNESDAY AND THURSDAY. WILL
HAVE TO WATCH FOR A POTENTIAL DRY SLOT TO LIMIT CONVECTION...BUT
AS LONG AS THE MODELS KEEP THE WINDS EAST...NEED TO HAVE POPS IN
THERE. TEMPERATURES WILL MODERATE FROM THE LOWER 60S MONDAY TO THE
LOWER 70S TUESDAY AND HOLD AROUND THAT LEVEL THROUGH THE REST OF
THE WEEK. TWH
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS THIS MORNING...MAINLY SOUTH
OF A KBIL TO KLVM LINE...CONTINUE TO EXPAND AND MOVE
NORTHEAST...AND WILL BECOME MORE WIDESPREAD THROUGH THE DAY. THE
PRECIP WILL CONTINUE TO MOVE SLOWLY NORTHEAST AND SHIFT OUT OF THE
AREA OVERNIGHT. SOME OF THE STORMS WILL CONTAIN MODERATE TO
BRIEFLY HEAVY RAINFALL AND COULD LOWER CONDITIONS TO MVFR. PATCHY
FOG REPORTED EAST OF A KBIL TO KSHR LINE IS LIFTING...AND SHOULD
CLEAR OUT BY LATE MORNING. MOUNTAINS WILL BE OBSCURED IN SHOWERS
AND CLOUDS THROUGHOUT THE DAY. AAG/TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 062 048/058 048/062 045/071 047/071 049/071 049/076
+/T 88/T 86/W 31/B 13/T 42/T 22/T
LVM 060 041/057 040/059 037/066 041/071 040/067 041/071
8/T 77/T 85/W 31/B 14/T 43/T 33/T
HDN 064 048/062 047/062 044/071 045/073 049/074 048/078
+/T 98/T 86/W 31/E 12/T 32/T 22/T
MLS 068 051/063 049/062 046/068 046/071 050/071 048/075
+/T +8/T 86/W 53/W 22/T 22/T 22/T
4BQ 069 048/059 047/060 043/063 044/071 048/071 047/075
+/T +8/T 87/W 53/W 11/B 22/T 21/B
BHK 068 048/060 047/060 043/061 043/067 048/067 048/070
8/T +8/T 86/W 53/W 21/B 22/T 22/T
SHR 065 047/056 043/057 040/064 040/073 046/072 045/076
9/T 67/T 86/W 42/W 12/T 32/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
335 AM MDT SAT MAY 18 2013
.SHORT TERM...VALID FOR TDY AND SUN...
RAINFALL TOTALING AN INCH OR MORE STILL LOOKS LIKE A GOOD BET OVER
THE NEXT FEW DAYS IN MANY AREAS. HOWEVER...THE 500-HPA TROUGH THAT
IS SET TO DRIVE ONE OF THE BETTER PRECIPITATION EVENTS WE HAVE HAD
IN A LONG TIME IS SURPRISING COMPLEX...SO SOME UNCERTAINTY EXISTS.
TODAY...THE MID-LEVEL SHORT WAVE TROUGH CENTERED NEAR 700 HPA THAT
IS SEEN ENTERING WESTERN WY ON 09 UTC MOISTURE CHANNEL IMAGES WILL
MOVE INTO SOUTHERN MT. THE ECMWF HAS BEEN THE MOST CONSISTENT WITH
BRINGING THIS BATCH OF FORCING INTO THE AREA IN THE LAST FEW DAYS.
ITS 00 UTC RUN CONTINUES THIS THEME...GENERATING CONVECTION ACROSS
MUCH OF THE AREA AFTER 18 UTC...WITH QPF AMOUNTS OF A QUARTER TO A
HALF INCH. THE 00 UTC GFS HAS FINALLY PICKED UP ON THIS SHORT WAVE
TOO...SO OUR CONFIDENCE IN PRECIPITATION HAS INCREASED ENOUGH THAT
WE HAVE CHOSEN TO ADVERTISE 90 TO 100 PERCENT POPS AFTER 18 UTC IN
THE BILLINGS...SHERIDAN...MILES CITY...AND BROADUS AREAS. THE 700-
500 HPA LAPSE RATES ARE MODEST AROUND 6 C/KM...BUT THERE IS ENOUGH
INSTABILITY /POCKETS OF MUCAPE UP TO 500 J/KG/ TO GENERATE THUNDER
AS WELL. CALIBRATED THUNDERSTORM PROBABILITIES OFF THE 03 UTC SREF
JUMP UP INTO THE 40 AND 50 PERCENT RANGE AFTER 18 UTC AS WELL. THE
SEVERE RISK IS NEGLIGIBLE THOUGH GIVEN THE EXPECTED INSTABILITY. A
CAUTIONARY NOTE ABOUT THE POP FORECAST IS THAT MANY WRF-BASED HIGH
RESOLUTION MODELS FROM 00 UTC CLUSTER CONVECTION FURTHER SOUTHEAST
FROM SHERIDAN TOWARD BROADUS...WHICH MAY ACTUALLY SUPPRESS SOME OF
THE PRECIPITATION FURTHER NORTH IN PLACES LIKE BILLINGS. NOTE THAT
WE ALSO DECIDED TO CARRY ONLY CHANCE POPS IN MANY PLACES BEFORE 18
UTC BASED ON UPSTREAM TRENDS AND RECENT RAP AND HRRR OUTPUT.
TONIGHT...WE CONTINUED LEANING ON THE 00 UTC ECMWF SOLUTION DURING
THE EVENING...WITH A CONCENTRATED AREA OF CATEGORICAL POPS FOR THE
PLAINS OF SOUTH CENTRAL AND SOUTHEASTERN MT BEFORE 06 UTC. WE THEN
LET POPS FALL BACK A BIT AFTER MIDNIGHT IN MANY AREAS SINCE 1/ THE
DIURNALLY-DRIVEN CONVECTION SHOULD DIMINISH WITH SUNSET...AND 2/ A
BREAK IN FORCING SHOULD TAKE PLACE AS THE 700-HPA SHORT WAVE MOVES
OUT AND/OR WEAKENS. IF THE ECMWF IS CORRECT...WE MAY ACTUALLY HAVE
A RELATIVELY DRY PERIOD AFTER 06 UTC. HOWEVER...THE 00 UTC GFS AND
EVEN THE 03 UTC SREF KEEP MORE STRATIFORM-BASED PRECIPITATION OVER
SOUTH CENTRAL MT AND NORTH CENTRAL WY RIGHT THROUGH THE NIGHT...SO
WE WERE CAUTIOUS ABOUT LOWERING POPS BELOW THE LIKELY THRESHOLD AT
THIS POINT. WE ALSO KEPT IN ISOLATED THUNDERSTORMS FOR MOST OF THE
AREA AFTER 06 UTC...BUT WE MIGHT BE ABLE TO DROP THAT MENTION WITH
LATER FORECASTS SINCE MUCAPE AND THE SREF THUNDERSTORM PROBABILITY
VALUES BOTH DWINDLE NOCTURNALLY.
ON SUN...A 500-HPA TROUGH IS EXPECTED TO CLOSE OFF...LIKELY ACROSS
WY...AND THAT SHOULD DRIVE A MORE STEADY RAIN EVENT ACROSS PART OR
EVEN ALL OF THE AREA. THIS IS THE POINT WHERE COMPLEX INTERACTIONS
OF SHORT WAVES AND CONVECTION WITHIN THE LARGER-SCALE TROUGH COULD
ULTIMATELY DICTATE WHERE AND HOW MUCH RAIN FALLS. WE INCREASED THE
POPS ONE MORE TIME THOUGH SO THAT THEY ARE CATEGORICAL FOR MUCH OF
THE AREA SINCE THERE IS FAIR AGREEMENT AMONG 00 UTC MODELS. LIKELY
AND CATEGORICAL POPS CONTINUE INTO SUN NIGHT.
HYDROLOGY-WISE...WE DECIDED TO LET GO OF THE FLASH FLOOD WATCH FOR
THE BURN SCAR AREAS WITH THIS FORECAST RELEASE. THE RAINFALL RATES
OVER THE NEXT FEW DAYS ARE NOT EXPECTED TO BE LARGE ENOUGH TO NEED
AN EXTENSION OF THE WATCH...THOUGH WE WILL CERTAINLY BE KEEPING AN
EYE ON THOSE BURN SCAR AREAS REGARDLESS. OTHERWISE...THERE WILL BE
AT LEAST MINOR RISES ON AREA RIVERS AND STREAMS IN THE COMING DAYS
IF THE FORECAST PRECIPITATION AMOUNTS COME TO FRUITION. HOWEVER...
NO FLOODING IS EXPECTED BECAUSE OUR VERY DRY SOILS WILL BE ABLE TO
EASILY ABSORB MUCH OF THE MOISTURE. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE EXTENDED PERIOD STARTS ON MONDAY AND MODEL DIFFERENCES MUDDY
THE WATERS ON TIMING OF PRECIPITATION TAPERING OFF OVER THE AREA.
BOTH MODELS MOVE THE UPPER LOW THAT WILL IMPACT THE AREA THIS
WEEKEND INTO EASTERN SOUTH DAKOTA BY 00Z TUESDAY. THE GFS BUILDS
THE RIDGE IN MUCH MORE AGGRESSIVELY AND SENDS WRAP AROUND ENERGY
AND MOISTURE SOUTH INTO WYOMING. THE ECMWF...HOWEVER...WAS SLOWER
WITH BUILDING HEIGHTS AND THIS ALLOWS ENERGY TO WRAP BACK INTO
EASTERN AND CENTRAL ZONES MONDAY. WILL SIDE WITH THE ECMWF AS THIS
WAS THE CONSENSUS OF SURROUNDING OFFICES AS OFTEN TIMES THESE
SLOW MOVING UPPER LOWS ARE SLOWER TO DRY OUT THAN MODELS EXPECT.
SHOULD GET DRYING CONDITIONS FOR TUESDAY AS THE RIDGE BUILDS IN
EARNEST. THE NEXT UPPER LOW...WHICH IS PROGGED TO BE QUITE A BIT
DEEPER THAN ITS PREDECESSOR...MOVES INLAND WEDNESDAY. ENERGY DOES
SWING AROUND THE UPPER LOW AND DRIVES ACROSS WESTERN AND CENTRAL
ZONES WEDNESDAY AND THURSDAY. LOW LEVEL WINDS WILL BE EASTERLY AND
THIS SHOULD ALLOW DEWPOINTS TO BE ON THE RISE. DRIER AIR WILL GET
PULLED INTO THE SYSTEM BUT THE GFS HAS BACKED OFF ON THIS FROM
YESTERDAY. CAPES SHOULD INCREASE WITH EASTERLY WINDS INCREASING
LOW LEVEL DEWPOINTS. RAISED POPS OVER WESTERN AND CENTRAL ZONES
FOR AFTERNOON AND EVENING CONVECTION WEDNESDAY AND THURSDAY. WILL
HAVE TO WATCH FOR A POTENTIAL DRY SLOT TO LIMIT CONVECTION...BUT
AS LONG AS THE MODELS KEEP THE WINDS EAST...NEED TO HAVE POPS IN
THERE. TEMPERATURES WILL MODERATE FROM THE LOWER 60S MONDAY TO THE
LOWER 70S TUESDAY AND HOLD AROUND THAT LEVEL THROUGH THE REST OF
THE WEEK. TWH
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS THIS MORNING WILL BECOME MORE
WIDESPREAD BY EARLY AFTERNOON. THE PRECIPITATION WILL MOVE SLOWLY
NORTHEAST AND SHIFT OUT OF THE AREA OVERNIGHT. SOME OF THE STORMS
WILL CONTAIN MODERATE TO BRIEFLY HEAVY RAINFALL AND COULD LOWER
CONDITIONS TO MVFR. PATCHY FOG WILL BE POSSIBLE THIS MORNING EAST
OF A BILLINGS TO SHERIDAN LINE...WITH CONDITIONS DROPPING TO MVFR
LOCALLY. THE FOG WILL LIFT BY LATE MORNING. MOUNTAINS WILL BE
OBSCURED IN SHOWERS AND CLOUDS. TWH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 062 048/058 048/062 045/071 047/071 049/071 049/076
+/T 88/T 86/W 31/B 13/T 42/T 22/T
LVM 060 041/057 040/059 037/066 041/071 040/067 041/071
8/T 77/T 85/W 31/B 14/T 43/T 33/T
HDN 064 048/062 047/062 044/071 045/073 049/074 048/078
+/T 98/T 86/W 31/E 12/T 32/T 22/T
MLS 068 051/063 049/062 046/068 046/071 050/071 048/075
+/T +8/T 86/W 53/W 22/T 22/T 22/T
4BQ 069 048/059 047/060 043/063 044/071 048/071 047/075
+/T +8/T 87/W 53/W 11/B 22/T 21/B
BHK 068 048/060 047/060 043/061 043/067 048/067 048/070
8/T +8/T 86/W 53/W 21/B 22/T 22/T
SHR 065 047/056 043/057 040/064 040/073 046/072 045/076
9/T 67/T 86/W 42/W 12/T 32/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
116 PM CDT SAT MAY 18 2013
.MESOSCALE DISCUSSION...
ISSUED AT 1251 PM CDT SAT MAY 18 2013
SEVERE THUNDERSTORM POTENTIAL STILL ON TRACK THIS AFTERNOON AND
EVENING. LATEST SFC ANALYSIS HAS A SFC LOW PRESSURE CENTER LOCATED
IN EASTERN COLORADO...WITH A DRY LINE EXTENDING SOUTH FROM THE
LOW CENTER THROUGH THE TX PANHANDLE AND WARM FRONT EAST NORTHEAST
ACROSS NORTHERN KS. SFC LOW SHOULD CONTINUE TO LIFT SLOWLY
NORTHWARD TO NEAR GOODLAND BY LATE AFTERNOON A WARM FRONT WILL
ARC NORTHEAST INTO SOUTHWEST NEBRASKA FROM THE LOW CENTER.
THUNDERSTORMS SHOULD INITIATE AROUND IMPERIAL AND HAYES CENTER
AROUND 400 PM CDT ON THE NOSE OF VERY STEEP LOW LEVEL LAPSE
RATES/DRY LINE WHICH WILL BE PUNCHING INTO FAR SOUTHWEST NEBRASKA.
STORMS LIKELY TO BECOME SUPERCELLS QUICKLY AS THEY MOVE NORTHEAST
INTO A VERY TO EXTREMELY UNSTABLE AND FAVORABLE SHEARED
ATMOSPHERE. BACKED SFC WINDS TO THE SOUTHEAST ARE EXPECTED ACROSS
MOST OF SOUTHWEST NEBRASKA...WITH SPEEDS INCREASING JUST OFF THE
SFC EARLY THIS EVENING. THE TIME FRAME FROM 600 PM CDT TO 900 PM
CDT LOOKS TO BE THE MOST FAVORABLE FOR TORNADO DEVELOPMENT ACROSS
SOUTHWEST NEBRASKA. IN ADDITION TO THE TORNADO THREAT...VERY LARGE
HAIL...POSSIBLE BASEBALL SIZE OR LARGER...IS EXPECTED. STORMS WILL
LIKELY MERGE EARLY THIS EVENING INTO A COMPLEX AS THEY ADVANCE
NORTHEAST TOWARD CENTRAL AND NORTH CENTRAL NEBRASKA. LARGE HAIL
AND DAMAGING WINDS WILL BE THE MAIN THREATS FROM THE COMPLEX.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1251 PM CDT SAT MAY 18 2013
MVFR CONDITIONS WILL CONTINUE TO BE POSSIBLE ACROSS PORTIONS OF
WESTERN AND NORTH CENTRAL NEBRASKA THIS AFTERNOON IN AREAS OF
LOWER STRATUS CLOUDS.
TSTMS...SOME SEVERE...WILL DEVELOP ACROSS SOUTHWEST NEB LATE THIS
AFTERNOON...AND SPREAD NORTHEAST ACROSS THE ENTIRE AREA THROUGH
THE EVENING. WINDS WILL BE SOUTHEAST...BUT VARIABLE AND GUSTY NEAR
ANY STORM.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...TAYLOR
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1038 AM CDT SAT MAY 18 2013
.MESOSCALE DISCUSSION...
ISSUED AT 1019 AM CDT SAT MAY 18 2013
SEVERE THUNDERSTORM POTENTIAL STILL ON TRACK THIS AFTERNOON AND
EVENING. LATEST HAND SFC ANALYSIS HAS A 1004 MB SFC LOW PRESSURE
CENTER TO THE EAST OF LA JUNTA COLORADO...WITH A DRY LINE
EXTENDING SOUTH FROM THE LOW CENTER THROUGH THE TX PANHANDLE AND
WARM FRONT EAST NORTHEAST ACROSS NORTHERN KS. SFC LOW SHOULD LIFT
NORTH TO NEAR GOODLAND BY LATE AFTERNOON...WITH A WARM FRONT
ARCING NORTHEAST INTO SOUTHWEST NEBRASKA. THUNDERSTORMS SHOULD
INITIATE AROUND IMPERIAL AND HAYES CENTER BY MID TO LATE AFTERNOON
ON NOSE OF VERY STEEP LOW LEVEL LAPSE RATES/DRY LINE WHICH WILL BE
PUNCHING INTO FAR SOUTHWEST NEBRASKA. STORMS LIKELY TO BECOME
SUPERCELLS QUICKLY AS THEY MOVE NORTHEAST INTO A VERY TO EXTREMELY
UNSTABLE AND FAVORABLE SHEARED ATMOSPHERE. BACKED WINDS TO THE
SOUTHEAST ARE EXPECTED ACROSS MOST OF SOUTHWEST
NEBRASKA...ENHANCING THE THREAT FOR TORNADO DEVELOPMENT. IN
ADDITION TO THE TORNADO THREAT...VERY LARGE HAIL...POSSIBLE BASEBALL
SIZE OR LARGER...IS EXPECTED. STORMS WILL LIKELY MERGE EARLY THIS
EVENING INTO A COMPLEX AS THEY ADVANCE NORTHEAST TOWARD CENTRAL
AND NORTH CENTRAL NEBRASKA. LARGE HAIL AND DAMAGING WINDS WILL BE
THE MAIN THREATS FROM THE COMPLEX.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 616 AM CDT SAT MAY 18 2013
MVFR CIGS SHOULD ERODE WITH VFR DEVELOPING BETWEEN 17Z-19Z. SEVERE
STORMS COULD BEGIN DEVELOPING ACROSS SWRN NEB VCNTY KIML AROUND
20Z-22Z. STORM ACTIVITY WILL LIFT NORTH AND EAST THROUGH THE
EVENING HOURS. VFR COULD DEVELOP FROM WEST TO EAST BEGINNING
AROUND 03Z IN THE NEB PANHANDLE TO 09Z IN THE EAST SIDE OF THE
FCST AREA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
MESOSCALE...TAYLOR
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
619 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 616 AM CDT SAT MAY 18 2013
MVFR CIGS SHOULD ERODE WITH VFR DEVELOPING BETWEEN 17Z-19Z. SEVERE
STORMS COULD BEGIN DEVELOPING ACROSS SWRN NEB VCNTY KIML AROUND
20Z-22Z. STORM ACTIVITY WILL LIFT NORTH AND EAST THROUGH THE
EVENING HOURS. VFR COULD DEVELOP FROM WEST TO EAST BEGINNING
AROUND 03Z IN THE NEB PANHANDLE TO 09Z IN THE EAST SIDE OF THE
FCST AREA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
305 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE RAP13 SEEMS TO HAVE THE BEST HANDLE ON THE STRATUS LIFTING NORTH
INTO THE FCST AREA THIS MORNING. IT WAS ALSO THE PREFERRED MODEL FOR
THE SEVERE WEATHER EVENT EXPECTED TO UNFOLD LATE THIS AFTERNOON AND
TONIGHT. THE STRATUS SHOULD BUILD THROUGH THE FCST AREA ALONG AND
WEST OF HIGHWAY 83 THIS AM AND THEN MIX OUT LATE MORNING/EARLY
AFTERNOON.
THE ONGOING TSTMS AND ISOLD SEVERE STORMS SHOULD CONTINUE TO LIFT
NORTH AND EXIT THE FCST AREA BY SUNRISE. THEREAFTER THE RUC PUSHES
MOISTURE AND INSTABILITY FARTHER WEST THAN THE NAM AND SHARPENS UP
THE DRY LINE ACROSS WRN NEB THIS AFTERNOON. ALL THE WHILE
MAINTAINING A STRONG CAP WHICH SHOULD BREAK AROUND 22Z ON THE
DRYLINE. SPC PROVIDED USEFUL INSIGHT INTO THE EVOLUTION OF THIS
EVENT SUGGESTING LARGE/VERY LARGE HAIL AND WIND DAMAGE LATE THIS
AFTERNOON ALONG THE DRY LINE. THE CONVECTIVE COMPLEX MOVES EAST
TOWARD HIGHWAY 83 THIS EVENING. AT THE SAME TIME...LOW LEVEL WINDS
ARE EXPECTED TO BACK AND INCREASE IN SPEED TOWARD SUNSET OR SHORTLY
THEREAFTER ENHANCING THE TORNADO THREAT FOR A FEW HOURS...ROUGHLY
01Z-04Z.
THE ENTIRE SYSTEM OF STORMS WILL CONTINUE TO MOVE NORTHEAST
OVERNIGHT AND EXIT THE FCST AREA BY SUNDAY MORNING.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 AM CDT SAT MAY 18 2013
THE MODELS ARE IN RELATIVELY GOOD AGREEMENT REGARDING UPPER
TROUGH APPROACHING THE REGION ON SUNDAY. THE GFS AND ECMWF BOTH
HAVE THE TROUGH CLOSING OFF AND WRAPPING UP OVER SIOUX FALLS AREA
MONDAY THROUGH WEDNESDAY. THIS WILL MEAN COOLER CONDITIONS AND A
BROAD SCALE AREA OF PRECIPITATION POTENTIALLY ON THE BACK SIDE OF
THE LOW. LOOKING CLOSER AT SUNDAY...SEVERE THUNDERSTORMS WILL BE
POSSIBLE DURING THE AFTERNOON IN THE FAR EASTERN FORECAST AREA IN
VICINITY OF THE COLD FRONT ASSOCIATED WITH THE APPROACHING SYSTEM.
ON MONDAY AND TUESDAY...MODELS ARE INDICATING MOISTURE-RICH AIR
WRAPPING AROUND THE LOW PRESSURE SYSTEM INTO PARTS OF CENTRAL AND
WESTERN NEBRASKA. IT APPEARS THAT THE BEST CHANCE FOR
PRECIPITATION WITH THIS SYSTEM WILL BE IN NORTH-CENTRAL NEBRASKA.
HIGHS WILL DIP INTO THE MID 50S TO MID 60S ON MONDAY AND
TUESDAY...BEFORE REBOUNDING TO THE MID 60S TO MID 70S THURSDAY AND
FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1224 AM CDT SAT MAY 18 2013
MVFR CIGS WILL SPREAD NORTH ALONG HIGHWAYS 83 AND 61 OVERNIGHT.
THESE CIGS SHOULD ERODE TO VFR BY ROUGHLY 17Z-19Z. SCATTERED TO
NUMEROUS THUNDERSTORMS...SOME SEVERE...ARE EXPECTED TO DEVELOP
21Z-23Z AND CONTINUE THROUGH 06Z. STORM DEVELOPMENT WILL COMMENCE
IN THE SOUTH AND SPREAD NORTH.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...CDC
LONG TERM...KNUTSVIG
AVIATION...CDC
BELOW. LITTLE IF ANY CHANGE FROM THE PREVIOUS FORECAST DISCUSSION
IN THIS UPDATE.
THE WIND ADVISORY AND FLOOD WATCH WILL CONTINUE AS PREVIOUSLY
FORECAST...WITH A CLOSE METWATCH ON EVENING CONVECTIVE TRENDS IN
THE SOUTHERN JAMES RIVER VALLEY. LOCAL RIVERS/STREAMS WILL ALSO BE
MONITORED THROUGH THE NIGHT FOR ADDITIONAL UPDATES.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 330 PM CDT SUN MAY 19 2013
THE HIGHLIGHT OF THE SHORT TERM IS THE CONTINUED HEAVY RAINFALL
AND FLOODING THREAT ACROSS WESTERN AND CENTRAL NORTH DAKOTA
THROUGH MONDAY NIGHT AND A FLOOD WATCH REMAINS IN EFFECT.
OVERALL...THE DETERMINISTIC GUIDANCE IS IN GOOD AGREEMENT ON
RETROGRADING THE DEEP SURFACE LOW CURRENTLY ACROSS NORTHEAST SOUTH
DAKOTA WEST THROUGH TONIGHT...BEFORE PROPAGATING AGAIN EAST ON
MONDAY. GIVEN THE GOOD AGREEMENT...FOLLOWED A BLEND OF THE 12 UTC
GFS/GEM/ECMWF AND 15 UTC SREF FOR ALL FIELDS. THIS PLACES THE
LOW LEVEL DEFORMATION ZONE AND ASSOCIATED MODERATE TO HEAVY
RAINFALL GENERALLY ACROSS THE HIGHWAY 85 CORRIDOR AND INTO THE
NORTH CENTRAL THROUGH TONIGHT. WILL CONTINUE TO MONITOR THE JAMES
RIVER VALLEY LATE THIS AFTERNOON THROUGH EARLY EVENING AS BREAKS
IN THE CLOUD COVER IS ALLOWING SOME SURFACE BASED DESTABILIZATION
TO OCCUR. BEING SO CLOSE TO THE SURFACE LOW...DEEP LAYER SHEAR IS
MARGINAL FOR THIS PART OF THE CWA...HOWEVER...IT WOULD BE FAVORED
FOR A POSSIBLE WEAK SPIN- UP TORNADO/LAND SPOUT WITH THE LOW LEVEL
VORTICITY SHOULD SUFFICIENT NEAR SURFACE DESTABILIZATION OCCUR.
ALSO FOR TONIGHT...DID ISSUE WIND ADVISORY FOR WESTERN AND NORTH
CENTRAL NORTH DAKOTA FROM 00 UTC TO 15 UTC MONDAY. NAM/GFS BUFR
SOUNDINGS INDICATE 40-45 KTS TO MIX IN THE 900-875 MB LAYER AS THE
PRESSURE GRADIENT STRENGTHS WITH THE RETROGRADING SURFACE LOW.
FOR TOMORROW...AS ENERGY CURRENTLY ACROSS NEBRASKA PIVOTS AROUND
THE MAIN UPPER LEVEL LOW INTO NORTH DAKOTA...MODERATE TO HEAVY
RAIN WILL ONCE AGAIN BECOME WIDESPREAD ACROSS ALL OF WESTERN AND
CENTRAL NORTH DAKOTA. BY TUESDAY MORNING...AN ADDITIONAL TWO TO
THREE INCHES OF RAINFALL IS POSSIBLE FOR MUCH OF THE AREA. SEE THE
HYDROLOGY DISCUSSION BELOW FOR DETAILS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 PM CDT SUN MAY 19 2013
THE MAIN FORECAST ISSUE THROUGH THE LONG TERM PERIOD IS CONTINUED
HEAVY RAIN AND POTENTIAL FOR FLOODING. THE LATEST SUITE OF 19/12Z
MODELS IS IN VERY GOOD AGREEMENT REGARDING THE TRACK OF THE CLOSED
UPPER LOW THROUGH THE REGION. THE UPPER LOW MONDAY NIGHT IS FORECAST
TO BE OVER THE EASTERN DAKOTAS/WESTERN MINNESOTA BORDER...AND MOVE
SOUTHEASTWARD GRADUALLY TO SOUTHERN MINNESOTA BY DAYBREAK WEDNESDAY
MORNING...THEN MOVE EASTWARD INTO THE OHIO VALLEY AS ANOTHER UPPER
LEVEL LOW MAKES ITS WAY INTO THE WEST COAST. THIS CONSENSUS
INDICATES A PROLONGED PERIOD OF MODERATE TO HEAVY RAIN CONTINUING
MONDAY NIGHT INTO TUESDAY...IMPACTING MOST IF NOT ALL OF WESTERN AND
CENTRAL NORTH DAKOTA. SHOWERS ARE EXPECTED TO BECOME MORE SCATTERED
TUESDAY NIGHT INTO WEDNESDAY. RAINFALL AMOUNTS IN THE 24-HOUR PERIOD
FROM MONDAY NIGHT THROUGH TUESDAY NIGHT ARE EXPECTED TO RANGE FROM
AROUND 1/3 TO 2/3 OF AN INCH OVER A LARGE AREA OF WESTERN AND
CENTRAL NORTH DAKOTA. THIS IN ADDITION TO WHAT HAS ALREADY BEEN
RECEIVED THROUGH THIS WEEKEND...AND WHAT IS FORECAST FOR SUNDAY
NIGHT AND MONDAY...WILL KEEP FLOODING ISSUES THE MAIN THREAT ACROSS
THE REGION. IN ADDITION TO FLOODING CONCERNS ALONG SMALL
STREAMS...AND LOW LYING AREAS...WILL BE MONITORING RIVERS CLOSELY
THIS WEEK...ESPECIALLY THE FASTER RESPONDING POINTS SUCH AS APPLE
CREEK NEAR MENOKEN.
IN ADDITION TO THE RAINS...GUSTY WINDS ARE EXPECTED TO CONTINUE
MONDAY NIGHT THROUGH TUESDAY NIGHT...AS THE INTENSE UPPER LEVEL LOW
IS STACKED OVER THE SURFACE LOW...AND NORTHERLY WINDS FROM THE
SURFACE THROUGH H700 REMAIN UNIDIRECTIONAL FROM THE NORTH. EXPECTING
20 TO 30 MPH SUSTAINED WINDS WITH GUSTS TO NEAR 35 MPH AT TIMES.
UPPER LEVEL RIDGING WILL BECOME ESTABLISHED OVER THE REGION
BEGINNING WEDNESDAY AFTERNOON...AHEAD OF THE NEXT LARGE LOW PRESSURE
SYSTEM OVER THE WEST COAST/ROCKIES. THIS SYSTEM IS EXPECTED TO
REMAIN OVER THE ROCKIES AND BEGIN TO SET UP A SOUTHWESTERLY FLOW
ALOFT OVER THE NORTHERN PLAINS BY FRIDAY.
THE NEXT BEST CHANCE OF RAIN SHOWERS AND THUNDERSTORMS IS
FRIDAY...AND CONTINUING THROUGH THE WEEKEND.
EXPECT COOL WEATHER CONDITIONS TUESDAY WITH HIGHS IN THE
50S...WARMING GRADUALLY TO THE UPPER 60S AND 70S BY SATURDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 545 PM CDT SUN MAY 19 2013
MODERATE TO HEAVY RAINFALL WILL CONTINUE THROUGH THE TAF PERIOD
WITH MVFR/IFR CIGS/VSBYS. KISN/KDIK/KMOT AERODROMES WILL
EXPERIENCE THE CONDITIONS MENTIONED ABOVE THROUGH MONDAY.
KBIS/KJMS WILL SEE A RESPITE IN THE PRECIPITATION SUNDAY EVENING
WITH ONLY ISOLATED SHOWERS OR VCSH THROUGH 06Z. MORE RAIN WILL
DEVELOP AFTER 06Z AT KJMS AND THEN SPREAD WEST TO KBIS BY 10Z
MONDAY. THEREAFTER...MODERATE TO HEAVY RAINFALL WILL COMMENCE AT
KBIS AND KJMS.
&&
.HYDROLOGY...
ISSUED AT 842 PM CDT SUN MAY 19 2013
TWO MAIN CONCERNS THIS EVENING...HAVE COORDINATED WITH THE
MISSOURI BASIN RIVER FORECAST CENTER/MBRFC THIS EVENING...AND WILL
DO THE FOLLOWING...
1) APPLE CREEK AT MENOKEN HAS NOT RESPONDED TO THE RAPID RISE
THAT WAS FORECAST TO OCCUR ALREADY. THIS HAS BEEN DELAYED UNTIL
LATER TONIGHT. WITH THE RIVER FORECAST TO REMAIN JUST A HARE BELOW
MINOR FLOOD STAGE...WILL ISSUE AN RVS THIS EVENING WITH LATER
SHIFTS RE-EVALUATING...ESPECIALLY WITH MONDAYS RAINFALL.
2) WILL ISSUE A FLOOD WARNING FOR THE LITTLE MUDDY CREEK NEAR
WILLISTON. BELIEVE WE CAN ADD SOME VALUE/LEAD TIME HERE WITH
PROJECTIONS MAINTAINING A STEADY RISE WELL INTO MINOR FLOOD STAGE
BY LATE MONDAY NIGHT AND TUESDAY. WITH ADDITIONAL RAINS COMING
MONDAY...HAVE A HIGH DEGREE OF CONFIDENCE THAT CURRENT RISING
TRENDS WILL CONTINUE.
3) A FEW MORE RIVER FORECAST POINTS ARE FORECAST TO REACH MINOR
FLOOD STAGE IN THE COMING DAYS...BUT ENOUGH TIME REMAINS TO
MONITOR RAINFALL AMOUNTS MONDAY AND TUESDAY. WILL HOLD OFF ON
ISSUING ANY OTHER PRODUCTS PER COORDINATION WITH MBRFC...AND WILL
BRIEF THE ONCOMING SHIFT OF THESE DECISIONS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH TUESDAY MORNING FOR NDZ001>005-009>013-
017>023-025-031>037-040>048-050-051.
WIND ADVISORY UNTIL 10 AM CDT /9 AM MDT/ MONDAY FOR NDZ001>005-
009>013-017-018-031>033-040-043.
&&
$$
UPDATE...KS
SHORT TERM...AYD
LONG TERM...JV
AVIATION...KS
HYDROLOGY...KS/AYD
AREA FORECAST DISCUSSION
NWS BISMARCK ND
124 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 105 PM CDT SAT MAY 18 2013
THE DISCUSSION FROM THE PREVIOUS UPDATE REMAINS VALID AS THE MAIN
FOCUS IS STILL LOCATION AND TIMING OF CONVECTIVE INITIATION THIS
AFTERNOON.
THE ONLY NEW INFORMATION TO ADD IS THE PRESENCE OF LOW LEVEL
CONVERGENCE STRETCHING FROM DICKINSON TO BUFFALO SD. VISIBLE
SATELLITE INDICATES SOME AGITATED CUMULUS THERE...AND 18 UTC SPC
MESOANALYSIS INDICATES A MARKED INCREASE IN MIXED LAYER CAPE OVER
THE PAST HOUR. SHOULD THIS TREND CONTINUE...STRONGER STORMS MAY BE
REALIZED BY 4 PM CDT.
UPDATE ISSUED AT 1024 AM CDT SAT MAY 18 2013
THE TIMING AND LOCATION OF CONVECTIVE INITIATION IN THIS COMPLEX
SCENARIO IS THE MAIN FOCUS TODAY. PRECIPITATION CHANCES ALONG THE
MISSOURI RIVER HAVE GENERALLY BEEN LOWERED FOR THIS MORNING AND
EARLY AFTERNOON AS LOW LEVEL STRATUS WILL HELP TO STABILIZE THE
ATMOSPHERE UNTIL THE NEXT MID LEVEL SHORTWAVE ARRIVES THIS
AFTERNOON.
THE 12 AND 13 UTC HRRR HAVE PICKED UP ON THE CLEARING OVER
NORTHWESTERN SOUTH DAKOTA THIS MORNING...AND NOW INITIATES
CONVECTION THERE AND IN SOUTHWESTERN NORTH DAKOTA BY 21 UTC. 12
UTC GFS THERMODYNAMIC PROFILES SUPPORT THIS IDEA ALONG WITH THE 00
UTC ECMWF AS CAPE IS FORECAST TO EXCEED 1000 J/KG THERE.
THE CURRENT THINKING IS THAT CONVECTION WILL SPREAD GENERALLY
EAST-NORTHEASTWARD UNTIL MID/LATE AFTERNOON DESTABILIZATION AND
MIDDLE LEVEL HEIGHT FALLS FINALLY INITIATE ADDITIONAL CONVECTION
BETWEEN THE MISSOURI AND JAMES RIVERS ALONG THE DAKOTA BORDER.
UPDATE ISSUED AT 644 AM CDT SAT MAY 18 2013
UPDATE MAINLY FOR POP TRENDS TODAY. SHOWERS AND ISOLATED STORMS
HAVE PUSHED INTO THE FAR NORTHEAST EARLY THIS MORNING. RECENT RUNS
OF THE RAP HAVE A GOOD HANDLE ON NEAR TERM TRENDS...AND HAVE
REDUCED POPS THROUGH THE MORNING INTO EARLY AFTERNOON. STILL
EXPECTING THE FOCUS OF AFTERNOON CONVECTION ALONG A BOUNDARY TO
THE SOUTHEAST...WITH POTENTIAL FOR SOME SEVERE STORMS TO DEVELOP
BY MID AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 105 PM CDT SAT MAY 18 2013
LOW STRATUS HAS BEEN VERY DIFFICULT TO FORECAST TODAY...BUT
SHOULD LIFT AT ALL SITES BY 20 UTC. SHOWERS AND THUNDERSTORMS WILL
CAUSE MVFR CONDITIONS AT MOST TAF SITES TODAY...WITH BRIEF PERIODS
OF IFR POSSIBLE IN STRONGER STORMS. IFR/LIFR FOG AND LOW STRATUS
WILL LIKELY RETURN AFTER MIDNIGHT TONIGHT IN THE WAKE OF
PRECIPITATION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...SCHECK
SHORT TERM/LONG TERM...RP KINNEY
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
119 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 107 PM CDT SAT MAY 18 2013
AREA OF RAIN CONTINUES TO LIFT SLOWLY NORTH AND IS NOW ALONG THE
CANADIAN BORDER. NO MODEL REALLY HINTED AT THIS MUCH FROM 00Z AND
12Z RUNS. REST OF AREA DRY SOUTH OF HIGHWAY 2. SOME CLEARING IN SE
ND WORKING NORTH A BIT...AND IN THIS CLEAR AREA TEMPS IN THE 77 TO
80 DEGREE RANGE FROM TENNEY-WAHPETON TO FARGO-VALLEY CITY. DEW PTS
RANGE FROM UPPER 50S TO MID 60S IN THIS AREA. IT IS THIS AREA
WHICH WILL SEE CAPES 1500-2000 J/KG LATE TODAY...AND COULD SEE
STORM DEVELOPMENT. 12Z SPC WRF SHOWS SOME DEVELOPMENT FAR-DTL 22Z-
00Z WHEREAS HRRR SHOWS IT MORE AXN-BRD REGION. UPDATED POPS TO
SHOW THIS INCREASE IN POPS IN THE FAR SOUTH-SOUTHEAST AFTER 22Z.
DISC WITH WFO DLH/MPX WILL HOLD OFF ANY FFA FOR NOW HAS HEAVIEST
CONVECTION EARLIER THIS MORNING-LAST NIGHT WAS AXN-STC-BRD REGION
JUST TO OUR SOUTH.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 326 AM CDT SAT MAY 18 2013
FORECAST CHALLENGE THROUGH THE SHORT TERM WILL CONTINUE TO BE PCPN
CHANCES AS WELL AS SEVERE STORM AND HEAVY RAIN POTENTIAL. MODELS
IN FAIR AGREEMENT WITH MAIN FEATURES HOWEVER SUBTLE DIFFERENCES
EXIST WITH SURFACE LOW/BOUNDARY POSITIONS TODAY.
ARC OF WEAKENING CONVECTION LIFTING NE THROUGH FA AT 30KTS WILL
CONTINUE TO PROPAGATE NE THROUGH THE MORNING AND INTO EARLY
AFTERNOON. WILL ATTEMPT TO ADJUST/TIME POPS ACCORDINGLY.
TEMPERATURES WILL BE TRICKY AND DEPENDENT ON DEGREE OF CLOUD COVER
AND HOW FAR NORTH WARM FRONT GETS. WITH WARM COLUMN ANY BREAKS
WILL REALLY BOOST TEMPERATURES.
LATER TODAY AND INTO TONIGHT. SURFACE INVERTED TROUGH TO SHARPEN
ACROSS FA PROVIDING GOOD SOURCE OF LOW LEVEL CONVERGENCE. TOUGH TO
DETERMINE ANY SPECIFIC SHORT WAVE HOWEVER REGION COMES UNDER
ENTRANCE REGION OF MODEST JET STREAK WHICH WILL AID IN UPPER
SUPPORT. MODELS DIFFER ON LOCATION OF SURFACE LOW WHICH WILL RIDE
NORTHWARD ALONG TROUGH AS WELL AS POSITION OF WARM FRONTAL
BOUNDARY. MODELS INDICATING GOOD SURFACE MOISTURE FLUX WITH 60
DEWPOINTS SPREADING NORTHWARD THROUGH MOST OF FA. PRECIPITABLE H2O
VALUES INCREASE TO AROUND 1.5 BY EVENING. GREATEST INSTABILITY AND
CAPE ACROSS SOUTH HALF OF FA AND LOOKS TO BE THE FAVORED LOCATION
FOR SEVERE POTENTIAL. SOME CAPPING MAY INITIALLY DELAY CONVECTIVE
INITIATION DURING THE AFTERNOON. HEAVY RAIN POTENTIAL THERE BUT WITH
DIFFERENCES IN SURFACE LOW POSITION TO ENHANCE LOW LEVEL
CONVERGENCE NOT AS CLEAR CUT.
INVERTED TROUGH TO DRIFT EAST SUNDAY WHICH WILL PUT HEAVIER RAIN
THREAT INTO MN. TEMPERATURES TO BE QUITE A BIT COOLER ON BACK SIDE
OF INVERTED TROUGH.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 326 AM CDT SAT MAY 18 2013
CUT OFF LOW TAKES OVER AND DRIFTS ACROSS E SD INTO S MN TO START WORK
WEEK FOR CONTINUED MODERATE RAIN POTENTIAL AND COOLER TEMPERATURES.
TUESDAY-FRIDAY...THE UPPER LOW WILL SLOWLY SHIFT EASTWARD FROM THE
CENTRAL/NORTHERN PLAINS INTO THE GREAT LAKES DURING THIS PERIOD. THE
00Z GFS/12Z ECMWF BEGIN TO SHIFT SHOWER ACTIVITY SOUTH AND EAST ON
WEDNESDAY...WITH THE GEM SLOWER IN ENDING THE PRECIP. WILL CONTINUE
TO MENTION POPS ACROSS THE SOUTHEAST THROUGH WEDNESDAY NIGHT. SFC
HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE AREA TOWARDS THE END
OF THE WEEK AS MID/UPPER LEVEL RIDGING DEVELOPS ACROSS THE PLAINS.
BELOW NORMAL TEMPS WILL MODERATE BACK TO NEAR NORMAL BY LATE NEXT
WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 107 PM CDT SAT MAY 18 2013
ACROSS NERN ND AND NRWN MN...AREAS OF IFR TO LIFR CIGS AND VSBYS
ALG AND NORTH OF U.S. HWY 2 WILL SLOWLY LIFT AND SHIFT NORTHWARD
THIS AFTERNOON...WITH SCT MVFR CIGS LIKELY TO PERSIST INTO THE
EVENING. SCT TSTMS ARE EXPECTED TO DEVELOP FROM LATE AFTERNOON
INTO THE EARLY EVENING...BECOMING MORE NUMEROUS INTO THE LATE
EVENING. ACROSS SERN ND INTO WCNTRL MN...AREAS OF LIFR TO IFR CIGS
AND VSBYS ALG AND EAST OF AN AXN-BJI LINE WILL SLOWLY LIFT AND
SHIFT NORTHEASTWARD THROUGH THIS AFTERNOON...WITH SCT MVFR CIGS
LIKELY TO PERSIST INTO THE EVENING. OTHERWISE...FAIR SKIES OVER
THE SOUTHERN RRV WILL ALLOW FOR INCREASED SFC HEATING AND THE
DEVELOPMENT OF SCT TSTMS /WITH ISOLD LARGE HAIL/ FROM MID
AFTERNOON INTO THE EARLY EVENING...BECOMING MORE NUMEROUS INTO
MIDNIGHT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...RIDDLE
SHORT TERM...VOELKER
LONG TERM...MAKOWSKI/VOELKER
AVIATION...GUST
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1046 AM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1024 AM CDT SAT MAY 18 2013
THE TIMING AND LOCATION OF CONVECTIVE INITIATION IN THIS COMPLEX
SCENARIO IS THE MAIN FOCUS TODAY. PRECIPITATION CHANCES ALONG THE
MISSOURI RIVER HAVE GENERALLY BEEN LOWERED FOR THIS MORNING AND
EARLY AFTERNOON AS LOW LEVEL STRATUS WILL HELP TO STABILIZE THE
ATMOSPHERE UNTIL THE NEXT MID LEVEL SHORTWAVE ARRIVES THIS
AFTERNOON.
THE 12 AND 13 UTC HRRR HAVE PICKED UP ON THE CLEARING OVER
NORTHWESTERN SOUTH DAKOTA THIS MORNING...AND NOW INITIATES
CONVECTION THERE AND IN SOUTHWESTERN NORTH DAKOTA BY 21 UTC. 12
UTC GFS THERMODYNAMIC PROFILES SUPPORT THIS IDEA ALONG WITH THE 00
UTC ECMWF AS CAPE IS FORECAST TO EXCEED 1000 J/KG THERE.
THE CURRENT THINKING IS THAT CONVECTION WILL SPREAD GENERALLY
EAST-NORTHEASTWARD UNTIL MID/LATE AFTERNOON DESTABILIZATION AND
MIDDLE LEVEL HEIGHT FALLS FINALLY INITIATE ADDITIONAL CONVECTION
BETWEEN THE MISSOURI AND JAMES RIVERS ALONG THE DAKOTA BORDER.
UPDATE ISSUED AT 644 AM CDT SAT MAY 18 2013
UPDATE MAINLY FOR POP TRENDS TODAY. SHOWERS AND ISOLATED STORMS
HAVE PUSHED INTO THE FAR NORTHEAST EARLY THIS MORNING. RECENT RUNS
OF THE RAP HAVE A GOOD HANDLE ON NEAR TERM TRENDS...AND HAVE
REDUCED POPS THROUGH THE MORNING INTO EARLY AFTERNOON. STILL
EXPECTING THE FOCUS OF AFTERNOON CONVECTION ALONG A BOUNDARY TO
THE SOUTHEAST...WITH POTENTIAL FOR SOME SEVERE STORMS TO DEVELOP
BY MID AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1024 AM CDT SAT MAY 18 2013
LOW STRATUS HAS BEEN VERY DIFFICULT TO FORECAST THIS MORNING...BUT
SHOULD IMPROVE BY 18 UTC. SHOWERS AND THUNDERSTORMS WILL CAUSE
MVFR CONDITIONS AT MOST TAF SITES TODAY...WITH BRIEF PERIODS OF
IFR POSSIBLE IN STRONGER STORMS. FOG AND LOW STRATUS WILL LIKELY
RETURN AFTER MIDNIGHT TONIGHT IN THE WAKE OF PRECIPITATION.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...SCHECK
SHORT TERM/LONG TERM...RP KINNEY
AREA FORECAST DISCUSSION
NWS BISMARCK ND
644 AM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 644 AM CDT SAT MAY 18 2013
UPDATE MAINLY FOR POP TRENDS TODAY. SHOWERS AND ISOLATED STORMS
HAVE PUSHED INTO THE FAR NORTHEAST EARLY THIS MORNING. RECENT RUNS
OF THE RAP HAVE A GOOD HANDLE ON NEAR TERM TRENDS...AND HAVE
REDUCED POPS THROUGH THE MORNING INTO EARLY AFTERNOON. STILL
EXPECTING THE FOCUS OF AFTERNOON CONVECTION ALONG A BOUNDARY TO
THE SOUTHEAST...WITH POTENTIAL FOR SOME SEVERE STORMS TO DEVELOP
BY MID AFTERNOON.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 430 AM CDT SAT MAY 18 2013
AREA OF SHOWERS AND SCATTERED THUNDERSTORMS CONTINUE TO PUSH
NORTH AND EAST AS A MID LEVEL DISTURBANCE LIFTS NORTHEAST ACROSS
CENTRAL NORTH DAKOTA EARLY THIS MORNING. PRECIPITATION HAS ENDED
AT KBIS-KDIK-KISN...AND WILL END BY 15Z FOR KMOT-KJMS. HIGH LOW
LEVEL MOISTURE WILL RESULT IN AREAS OF FOG AND POSSIBLE VLIFR
STRATUS THIS MORNING AT MOST IF NOT ALL TERMINALS. WHILE THE
STRATUS AND FOG SHOULD LIFT BY MID MORNING...IT MAY LINGER AT KMOT
INTO SATURDAY AFTERNOON...THEN DEVELOP OVER ALL TERMINALS ONCE
AGAIN SATURDAY NIGHT.
SHOWERS AND THUNDERSTORMS WILL REDEVELOP AFTER 18Z SATURDAY
AFTERNOON...DEVELOPING NORTH AND EAST INTO SATURDAY NIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/SHORT TERM/LONG TERM...RP KINNEY
AVIATION...NH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
430 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
THE MAIN FOCUS IN THE SHORT TERM IS CONVECTIVE TRENDS AND
POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON AND TONIGHT. IN THE
NEAR TERM...THE 18/07Z RAP MODEL HAS A GOOD HANDLE ON THE LOCATION
OF THE CURRENT STORMS ACROSS THE NORTHEAST HALF OF THE FORECAST
AREA. STORMS SHOULD CONTINUE TO LIFT NORTH THROUGH THE MORNING
HOURS. AFTERNOON REDEVELOPMENT IS EXPECTED TO FOCUS ON THE TROUGH
EXTENDING ACROSS THE SOUTHEAST COUNTIES. ML CAPES AROUND 1500 TO
2000 J/KG ARE EXPECTED ALONG WITH DEEP LAYER SHEAR AT OR ABOVE 40
KTS...SUFFICIENT FOR SUPERCELL DEVELOPMENT WITH LARGE
HAIL/DAMAGING WIND THREAT. IN THE EXTREME SOUTHEAST...LOW
LCL`S...DECENT LOW LEVEL CAPE...AND A NARROW AREA OF FAVORABLE
0-1KM SHEAR SUGGEST THERE MAY ALSO BE A SEVERAL HOUR WINDOW OF
TORNADO THREAT THROUGH EARLY EVENING.
THE SOUTHEAST HALF OF THE FORECAST AREA LOOKS FAVORED FOR THE
HEAVIER RAINFALL AMOUNTS THROUGH TONIGHT. SIGNIFICANT RISES ON
MAINSTEM RIVERS ARE NOT EXPECTED...BUT WILL BE MONITORING FOR
LOCALIZED HEAVY RUNOFF AND ISOLATED SHORT TERM FLOODING DUE TO
EXTREME RAINFALL RATES OR MULTIPLE ROUNDS OF STORMS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 430 AM CDT SAT MAY 18 2013
A LARGE CLOSED H5 LOW IS FORECAST TO DRIFT THROUGH THE REGION
SUNDAY THROUGH TUESDAY. THE THREAT FOR SEVERE WEATHER WILL
DIMINISH DURING THIS PERIOD...BUT MODERATE TO LOCALLY HEAVY RAINFALL
WILL PERSIST. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 3 INCHES ARE
POSSIBLE OVER THE WEEKEND THROUGH TUESDAY...WITH THE HIGHER TOTALS
TOWARD THE JAMES RIVER VALLEY. AGAIN...SIGNIFICANT RESPONSES ARE
NOT EXPECTED ON AREA RIVERS...BUT WILL BE WATCHING SMALLER CREEKS
AND STREAMS...AS WELL AS THE POTENTIAL FOR URBAN FLOODING. CLOUDS
AND RAIN WILL KEEP TEMPS DOWN IN THE 50S/LOWER 60S MONDAY AND
TUESDAY...BEFORE A WARMING TREND FROM MID TO LATE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 430 AM CDT SAT MAY 18 2013
AREA OF SHOWERS AND SCATTERED THUNDERSTORMS CONTINUE TO PUSH
NORTH AND EAST AS A MID LEVEL DISTURBANCE LIFTS NORTHEAST ACROSS
CENTRAL NORTH DAKOTA EARLY THIS MORNING. PRECIPITATION HAS ENDED
AT KBIS-KDIK-KISN...AND WILL END BY 15Z FOR KMOT-KJMS. HIGH LOW
LEVEL MOISTURE WILL RESULT IN AREAS OF FOG AND POSSIBLE VLIFR
STRATUS THIS MORNING AT MOST IF NOT ALL TERMINALS. WHILE THE
STRATUS AND FOG SHOULD LIFT BY MID MORNING...IT MAY LINGER AT KMOT
INTO SATURDAY AFTERNOON...THEN DEVELOP OVER ALL TERMINALS ONCE
AGAIN SATURDAY NIGHT.
SHOWERS AND THUNDERSTORMS WILL REDEVELOP AFTER 18Z SATURDAY
AFTERNOON...DEVELOPING NORTH AND EAST INTO SATURDAY NIGHT.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM/LONG TERM...RP KINNEY
AVIATION...NH
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1141 PM CDT FRI MAY 17 2013
.UPDATE...
ISSUED AT 1141 PM CDT FRI MAY 17 2013
LOWERED TEMPS A BIT IN THE NORTHWESTERN CWA WHERE READINGS HAVE
ALREADY FALLEN INTO THE MID 50S. THINK THAT TEMPS WILL LEVEL OFF
AROUND 50 AS CLOUDS CONTINUE TO INCREASE BUT TEMPS ALREADY AT
FORECAST LOWS. RADAR SHOWS THAT STORMS CONTINUE TO BE ON TRACK TO
ENTER THE SOUTHWESTERN CWA AFTER MIDNIGHT AND CONTINUE
NORTHEASTWARD. SEE LITTLE REASON TO MAKE MORE ADJUSTMENTS TO THE
TIMING OF POPS AT THIS POINT.
UPDATE ISSUED AT 927 PM CDT FRI MAY 17 2013
ADJUSTED POPS/WX BASED ON CURRENT RADAR TIMING. STORMS FIRING
ALONG THE 850MB WARM AIR ADVECTION IN CENTRAL MN WILL CLIP OUR
SOUTHEASTERN COUNTIES...SO INCLUDED A SCATTERED MENTION FOR THE
REST OF THE EVENING. STORMS FIRING OVER WESTERN ND AND SD WILL
MOVE NORTHEASTWARD INTO THE SOUTHERN RED RIVER VALLEY LATER
TONIGHT. IF CURRENT MOTION HOLDS...THE ACTIVITY SHOULD ARRIVE AT
OUR SOUTHERN BORDER AROUND MIDNIGHT AND MOVE NORTHEASTWARD
THROUGHOUT THE EARLY MORNING HOURS. TWEAKED TIMING OF POPS MOVING
INTO THE AREA WITH LIKELY WORDING TRANSITIONING FROM THE SOUTH
JUST AFTER MIDNIGHT TO THE NORTH BY TOMORROW MORNING. ELEVATED CAP
VALUES ARE AROUND 1000 J/KG ACCORDING TO THE SPC MESOANALYSIS.
THINK THAT THE BEST LLJ WILL STAY TO OUR SOUTH BUT SOME ISOLATED
SEVERE HAIL OR WIND IS NOT OUT OF THE QUESTION AROUND THE 06-12Z
TIME FRAME. HOWEVER...CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE IN
THE GRIDS AT THIS POINT SO WILL JUST KEEP GENERAL THUNDER GOING.
UPDATE ISSUED AT 652 PM CDT FRI MAY 17 2013
ADJUSTED POPS ALONG THE CANADIAN BORDER FOR THE NEXT FEW HOURS TO
ACCOUNT FOR THE WEAK SHOWERS/SPRINKLES DEVELOPING IN THAT AREA.
HOWEVER...THE MAIN PRECIP IS WELL TO OUR SOUTH...SO KEPT THE HIGH
POPS RESERVED FOR AFTER MIDNIGHT AS THE GOING FORECAST HAS.
TWEAKED CLOUDS TO INCLUDE CLEARING IN OUR SOUTHWESTERN COUNTIES
BUT THAT WILL NOT LAST LONG AS BLOW OFF FROM CONVECTION FROM OUR
SOUTHWEST BEGINS TO MOVE IN. SHOULD BE TOTALLY CLOUDY AFTER
MIDNIGHT.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 330 PM CDT FRI MAY 17 2013
THE MAIN CONCERNS WILL BE HEAVY RAIN AND SEVERE POTENTIAL. 12Z
MODELS IN DECENT AGREEMENT WITH SYNOPTIC FEATURES...BUT STILL
ENOUGH DIFFERENCES THAT CONFIDENCE IS LOW WITH DETAILS.
WEST COAST TROUGH WILL GRADUALLY PROPAGATE EAST WITH MULTIPLE
SHORTWAVES EJECTING INTO THE REGION. HARD TO PINPOINT EXACTLY WHEN
AND WHERE THE BEST THUNDER CHANCES WILL BE...BUT THE MODELS DO
OFFER A COUPLE STRONGER SIGNALS. THE FIRST BEST CHANCE IS TONIGHT
INTO SATURDAY MORNING AS MENTIONED IN THE PREVIOUS AFD (1243PM).
18Z HRRR DOES INDICATE A THUNDERSTORM COMPLEX MOVING INTO THE
SOUTHERN FA AFTER 06Z...ALONG WITH WITH ISOLATED STRONGER STORMS.
THIS COMPLEX SHOULD MOVE THROUGH FAIRLY QUICKLY...WITH UP TO 0.5
INCH AREAL QPF POSSIBLE.
THINKING THERE WILL BE A BRIEF BREAK IN ACTIVITY ON SATURDAY.
SEVERE POTENTIAL WILL DEPEND ON HOW FAR NORTH THE SURFACE WARM
FRONT WILL MAKE IT BY SATURDAY AFTERNOON. THE GEM/GFS BRING THIS
FEATURE MUCH FURTHER NORTH THAN OTHER MODELS (LIKELY BECAUSE THEY
ARE STRONGER WITH A SHORTWAVE INTO SOUTHERN CANADA). AT ANY
RATE...GIVEN THIS TIME OF YEAR WITHOUT EVAPOTRANSPIRATION...THE
NAM SEEMS TO HAVE THE CORRECT IDEA INDICATING MLCAPE 1000-1500
J/KG WITHIN THE WARM SECTOR. THIS INSTABILITY ALONG WITH DEEP
LAYER SHEAR 30-35 KNOTS SHOULD BE ENOUGH FOR LIMITED SEVERE
POTENTIAL WITHIN THE WARM SECTOR AS THE COLD FRONT SLOWLY
PROPAGATES EAST INTO THE EVENING HOURS.
THE BEST CHANCE FOR FLASH FLOODING POTENTIAL WOULD BE SATURDAY
EVENING AND OVERNIGHT ALONG THE SLOW MOVING BOUNDARY. THE BIGGEST
QUESTIONS AT THIS POINT WILL BE THE EXACT LOCATION OF THIS
FEATURE...AND HOW QUICKLY IT WILL MOVE TO THE EAST. NOT ENOUGH
CONFIDENCE FOR A FLASH FLOOD WATCH AT THIS POINT...BUT THERE IS A
SLIGHT RISK FOR FLASH FLOODING ALONG AND EAST OF THE VALLEY.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 330 PM CDT FRI MAY 17 2013
SUNDAY-MONDAY...UPPER LOW WILL CLOSE OFF JUST SOUTH OF THE FA AND
BRING PERIODIC SHOWERS AND THUNDERSTORMS TO THE REGION.
INSTABILITY IS MUCH WEAKER BY THIS TIME...BUT GIVEN HIGH PWATS AN
ADDITIONAL 1-2 INCHES OF RAINFALL IS POSSIBLE (ESPECIALLY THE
SOUTHERN HALF OF THE FA). THIS RAINFALL WOULD OVER A COUPLE DAYS
AND ANY FLOOD THREAT IS DEPENDENT ON WHAT OCCURS SATURDAY/SATURDAY
NIGHT.
MONDAY NIGHT-FRIDAY...12Z GFS/12Z ECMWF IN PRETTY GOOD AGREEMENT
IN SHOWING THE 500 MB LOW OVER EASTERN SD/MN REGION TUESDAY THEN
DRIFTING A BIT SOUTH AND EAST WEDNESDAY AND THEN EAST OF THE AREA
THURSDAY. LOOK FOR A CONTINUED HIGH THREAT FOR SHOWERS
TUESDAY...DIMINISHING ON WEDNESDAY. A 500 MB RIDGE WILL BUILD IN
BEHIND THE LOW FOR THE END OF THE WEEK WITH DRY WEATHER RETURNING.
LOOK FOR TEMPS TO BIT A BIT BELOW NORMAL WITH THE CLOUDS/RAIN TUE-
WED THEN RETURN TO CLOSE TO NORMAL LEVELS BY LATE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1141 PM CDT FRI MAY 17 2013
CEILINGS HAVE GONE DOWN TO MVFR AT KFAR AND THE LOWER CONDITIONS
WILL CONTINUE TO SPREAD NORTHWARD THROUGH MUCH OF THE NIGHT.
WEAKENING STORMS WILL ENTER THE FORECAST AREA AFTER
MIDNIGHT...MOVING INTO KFAR AREA AROUND 07-08Z WITH SOME THUNDER
REMAINING AND CONTINUING NORTH AS MOSTLY SHOWERS LATER ON THIS
MORNING. THINK THERE SHOULD BE SOME IMPROVEMENT TO VFR CONDITIONS
ACROSS MOST AREAS DURING THE AFTERNOON ALTHOUGH WILL HAVE TO WATCH
THE NORTHERN SITES WHICH MAY BE ON THE NORTH SIDE OF A WARM FRONT
AND STAY SOCKED IN. KFAR HAS THE BEST CHANCE OF SEEING SOME
CONVECTIVE REDEVELOPENT TOWARDS THE END OF THE PERIOD.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JR
SHORT TERM...TG
LONG TERM...TG/RIDDLE
AVIATION...JR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
619 PM EDT SAT MAY 18 2013
.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND WILL MAINTAIN A RIDGE OVER THE
EASTERN GREAT LAKES INTO SUNDAY BEFORE SHIFTING OFF THE COAST. MEANWHILE
A NEARLY STATIONARY FRONT ACROSS SOUTHERN OHIO WILL LIFT BACK NORTH
LATE SUNDAY. SOUTHERLY FLOW WILL BRING MORE HUMID AIR EARLY IN THE
WEEK AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. THE FRONT
SHOULD ARRIVE LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
NO SIGNIFICANT CHANGES TO FORECAST FOR THE UPDATE.
PREVIOUS...LIGHT SHOWERS CONTINUE TO DIMINISH ACROSS NORTH
CENTRAL OHIO AND SPC RUC ANALYSIS SHOWS INSTABILITY LIMITED TO
SOUTHERN OHIO. SATELLITE AND RADAR IMAGERY SUPPORT THAT WITH
SHOWERS DEVELOPING CLOSER TO THE OHIO RIVER. THE FORECAST THROUGH
THE REMAINDER OF THE EVENING WILL ONLY CARRY A CHANCE OF SPRINKLES
SOUTH OF A FDY-MFD-CAK LINE. OTHERWISE EXPECT CLOUD COVER TO
GRADUALLY DIMINISH THROUGH LATE EVENING...WITH SOME INCREASE
POSSIBLE FROM THE SOUTH LATE TONIGHT. TEMPERATURES WILL BOTTOM OUT
IN THE UPPER 50S TO NEAR 60 DEGREES.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
WEAK UPPER LEVEL DISTURBANCE SLOWLY SHIFTS TO THE EAST COAST THROUGH
SUNDAY NIGHT. MODELS SHOW THE STALLED FRONTAL BOUNDARY OVER THE OHIO
VALLEY SHIFTING BACK NORTH LATE SUNDAY WHICH WILL ALLOW LOW LEVEL
MOISTURE TO INCREASE. STILL NO OBVIOUS FORCING MECHANISM ON SUNDAY
AFTERNOON TO KICK OFF SHOWERS AND THUNDERSTORMS BENEATH THE BUILDING
RIDGE ALOFT SO WILL CONTINUE TO HOLD ONTO FAIRLY LOW POPS...WITH
BEST CHANCES FOCUSED SOUTH OF A FDY-YNG LINE. EXPECTING A LITTLE
LESS CLOUD COVER...ESPECIALLY IN NW OHIO WITH HIGHS RANGING FROM THE
UPPER 70S TO LOW 80S. ALTHOUGH MODELS ARE DRY ON SUNDAY NIGHT...HAVE
ADDED IN A LOW POP TO NW OHIO AS THETA E RIDGE LIFTS NORTH INTO THE
AREA. MODELS OFTEN STRUGGLE WITH DETECTING NOCTURNAL SHOWERS IN THIS
PATTERN AND NAM SOUNDINGS SHOW A FAIR AMOUNT OF ELEVATED INSTABILITY
TO WORK WITH. WILL CONTINUE THIS SLIGHT CHANCE EASTWARD ACROSS THE
AREA THROUGH MONDAY MORNING.
UPPER LEVEL LOW WILL DEVELOP OVER THE PLAINS ON SUNDAY AND SLOWLY
PUSH EASTWARD DURING THE EARLY PART OF NEXT WEEK. DEEP SOUTHERLY
FLOW WILL RESULT IN A MOISTENING AIRMASS WITH INCREASING CHANCES OF
SHOWERS AND THUNDERSTORMS. WITH THE RIDGE OVERHEAD...SLOWLY SHIFTING
EAST OF THE AREA...THE BETTER CHANCES OF SHOWERS AND THUNDERSTORMS
WILL BE ACROSS NORTHERN PORTIONS OF THE FORECAST AREA AS ENERGY
EJECTS OUT OF THE TROUGH AND TRIES TO MOVE AROUND THE RIDGE. MONDAY
WILL LIKELY BE CAPPED FOR MOST AREAS WITH CHANCES INCREASING ON
TUESDAY. TEMPERATURES WARM INTO THE MID 70S ON MONDAY...THEN DROP
BACK INTO THE LOW 80S ON TUESDAY AS CLOUDS AND THUNDERSTORMS
INCREASE. LOWS WILL BE MILD AS DEWPOINTS CREEP UP...DROPPING INTO
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
COMPLEX WEATHER PATTERN CONTINUES FOR THE EXTENDED PERIOD. THE
MODELS CONTINUE TO SHOW A SLOW MOVING STORM SYSTEM JUST TO THE WEST
OF THE FORECAST AREA. IT APPEARS MUCH OF THE FORECAST AREA WILL BE
IN THE WARM SECTOR IN ADVANCE OF THE STORM AS IT MOVES EAST. THE
UPPER LEVEL SHORT WAVE WILL MOVE ACROSS THE REGION WEDNESDAY NIGHT
INTO THURSDAY. THE 12Z RUN OF THE GFS IS SLOWER WITH THE
PROGRESSION OF THIS STORM THAN IT WAS YESTERDAY. THE BEST LIFT FROM
THE SURFACE FRONT AND UPPER LEVEL LOW APPEARED TO BE MORE ON
WEDNESDAY YESTERDAY AND IT LOOKS MORE LIKE WEDNESDAY NIGHT AND
THURSDAY WITH THIS RUN. IN EITHER CASE...THE MIDDLE PART OF NEXT
WEEK WILL BE UNSETTLED WITH SCATTERED STORMS THROUGHOUT. THE SLOWER
PROGRESSION OF THIS MODEL RUN WILL FORCE ME TO PUT SHOWERS IN THE
FORECAST THROUGH THE END OF NEXT WEEK.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS OVER THE TAF LOCATIONS WITH BKN/OVC MID TO HIGH
CLOUDS OVER MOST SITES. DEW POINT GRADIENT OVER THE CENTRAL
SECTIONS OF OHIO HAS MOVED A LITTLE FURTHER NORTH TODAY. I EXPECT
THE SHOWERS AND THUNDERSTORMS THAT FORMED ALONG THIS BOUNDARY TO
BE A LITTLE FURTHER NORTH THIS AFTERNOON. I WILL PLACE VCTS IN THE
SOUTHERN AND WESTERN TAF SITES INCLUDING TOL...FDY...MFD AND CAK.
VFR CONDITIONS SHOULD PERSIST OVERNIGHT. WITH THE HIGHER DEW
POINTS CREEPING NORTH IT IS POSSIBLE THAT SOME MVFR VSBYS COULD
FORM. WINDS WILL CONTINUE FROM A GENERAL EAST DIRECTION. TAF
LOCATIONS ALONG THE LAKE INCLUDING CLE AND ERI WILL SEE AN
AFTERNOON LAKE BREEZE THAT WILL SHIFT WINDS TO THE A NORTH TO
NORTHEAST DIRECTION.
.OUTLOOK...NON VFR POSSIBLE IN SHOWERS/THUNDERSTORMS THAT DEVELOP THROUGH
WEDNESDAY AND IN FOG THAT MAY OCCUR AROUND DAYBREAK.
&&
.MARINE...
EAST TO NORTHEAST WINDS CONTINUE OVER THE LAKE THIS AFTERNOON. A
FEW LOCATIONS REPORTING WIND SPEEDS IN THE 15 TO 20 KNOT RANGE.
THESE CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE EARLY EVENING
HOURS. THE 12Z BUFKIT RUN SHOWS A POCKET OF 20 TO 30 KNOT WINDS
WITHIN 1KFT OF THE SURFACE OVER THE WESTERN BASIN THROUGH 00Z. WITH
THE EAST TO NORTHEAST FETCH WAVE HEIGHTS COULD REACH 3 TO 5 FEET
OVER THE WEST. EVEN THOUGH THE CONDITIONS ARE MARGINAL...I WILL
CONTINUE THE SMALL CRAFT ADVISORY THROUGH THE EVENING. WINDS WILL
DECREASE OVERNIGHT TO 10 TO 15 KNOTS. A SIMILAR PATTERN WILL SETUP
ON SUNDAY BUT THE PRESSURE GRADIENT SHOULD BE WEAKER AND THEREFORE
THE WINDS NOT AS STRONG. I DO NOT ANTICIPATE SMALL CRAFT CRITERIA
FOR SUNDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LEZ142>145.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/TK
SHORT TERM...KEC
LONG TERM...GARNET
AVIATION...GARNET
MARINE...GARNET
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
600 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT ACROSS CENTRAL OHIO WILL DISSIPATE BY
MONDAY AS HIGH PRESSURE WILL HOLDS ALONG THE NEW ENGLAND COAST.
OUR FLOW WILL BECOME MORE SOUTHERLY AND MORE HUMID EARLY IN THE
WEEK AHEAD OF A COLD FRONT FROM THE WEST. THE FRONT SHOULD ARRIVE
LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY MORNING UPDATE...ADJUSTED SOME OF THE HOURLY TEMPERATURES
EARLY THIS MORNING THAT WERE RUNNING A COUPLE OF DEGREES WARMER
THAN FORECAST NEAR THE LAKE ERIE LAKESHORE. WILL HAVE TO WATCH A
FEW SHOWERS COMING NORTH FROM CENTRAL AND SOUTHWEST OHIO THAT
COULD SNEAK INTO THE AREA FROM AROUND MARION TO MOUNT VERNON EARLY
THIS MORNING.
EARLY MORNING ISSUANCE...MOSTLY BETWEEN SYSTEMS THIS
MORNING...WITH THE OVER RUNNING SYNOPTIC CLOUDS AND A FEW
SPRINKLES CLIPPING EASTERN LAKE ERIE AND AREAS EAST OF
PAINESVILLE. TO THE SOUTH THE OLD FRONTAL BOUNDARY IS NEAR
COLUMBUS.
THE ALTOCUMULUS ACROSS PARTS OF THE FORECAST AREA AND THE SPRINKLES
NEAR ERIE WILL THIN AND DISSIPATE EARLY THIS MORNING. THE OLD UPPER
LOW WELL TO OUR SOUTH WILL BEGIN TO LIFT OUT TO THE EAST-NORTHEAST
AND THE OLD FRONTAL BOUNDARY WILL SLOWLY BEGIN TO LIFT NORTH INTO
THE FORECAST AREA TODAY. NOT SURE HOW ACTIVE THE OLD FRONTAL
BOUNDARY WILL BECOME TODAY. THERE SHOULD BE WEAK SUBSIDENCE UNDER
THE BUILDING RIDGE ALOFT AND HIGH CLOUDS WILL SPREAD IN FROM THE
NORTHWEST LATE THIS MORNING. THIS COULD SUPPRESS CONVECTION. WILL
FORECAST RELATIVELY LOW POP...GENERALLY 10-35 PERCENT WITH THE
HIGHEST POP ACROSS THE SOUTH AND DRY (POP LESS THAN 15 PERCENT)
ALONG THE LAKE ERIE SHORE WHERE THE NORTHEAST FLOW OFF THE LAKE
SHOULD KEEP THINGS STABLE.
HIGH TEMPERATURES WILL BE SIMILAR TO YESTERDAY...PERHAPS A DEGREE
OR TWO COOLER AT INLAND LOCATIONS DUE TO THE INCREASE IN CLOUDS. A
COUPLE OF DEGREES WARMER NEAR LAKE ERIE WHERE THE WIND IS NOT OFF
THE WATER THIS MORNING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
AS THE DRY EAST-NORTHEAST FLOW BECOMES SOUTHERLY EARLY IN THE WEEK
WE WILL SEE INCREASINGLY HUMID CONDITIONS. THE OLD FRONTAL BOUNDARY
WILL LIFT NORTH OF THE AREA OR DISSIPATE ON MONDAY. INSTABILITY WILL
INCREASE BUT THERE IS NOT MUCH OF A TRIGGER FOR THUNDERSTORMS UNTIL
TUESDAY INTO WEDNESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE
WEST. WILL CONTINUE WITH A SMALL CHANCE OF SHOWERS/THUNDERSTORMS ON
MONDAY THEN A BETTER CHANCE OF SHOWERS/STORMS TUESDAY INTO
WEDNESDAY. FORECAST HIGHS WILL GENERALLY BE IN THE LOWER AND MID
80S. WITH ENOUGH SUN AND LACK OF SHOWERS COULD EVEN SEE UPPER 80S IN
A FEW LOCATIONS MONDAY OR TUESDAY. NOT AS WARM WEDNESDAY AS
SHOWERS/STORMS SHOULD BE MORE NUMEROUS BY THAT TIME.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
SOME ACTIVE WEATHER FOR THE PERIOD. THE MODELS ARE IN GENERAL
AGREEMENT WITH AN UPPER LOW MOVING ACROSS THE REGION THROUGH THE
PERIOD AND WITH A FRONT MOVING THROUGH THURSDAY AND THURSDAY NIGHT.
THE GFS KEEPS THE UPPER LOW ACROSS THE AREA FRIDAY WHILE THE GFS
MOVES THE LOW OUT. AT THIS TIME CONTINUING A GENERALLY DRY TREND
FRIDAY...EXCEPT KEPT 30 POPS OVER NW PA. USED A BLEND OF THE
GUIDANCE FOR THE TEMPERATURE FORECAST.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
AN IMPULSE ALOFT WAS CAUSE SOME VIRGA OR LIGHT SHOWERS OVER NW PA
AND EASTERN LAKE ERIE EARLY THIS AM...THIS SHOULD DECREASE BY
DAYBREAK. A FRONTAL BOUNDARY WAS STILL WEST TO EAST ACROSS CENTRAL
OHIO. AT THIS TIME THE TEMPERATURE AND DEW POINT SPREAD IS FAIRLY
HIGH AND WITH SOME MID CLOUDS NOT EXPECTING AS MUCH FOG AS LAST
NIGHT. SOME 3SM IS POSSIBLE AT FAVORED LOCATIONS...WITH QUICK DISSIPATION.
OTHERWISE FOR TODAY THE BOUNDARY WILL SLOWLY SHIFT NE TODAY. THE
AIR MASS IS MOIST AT MID LEVELS AND THE LOW LEVEL MOISTURE WILL
INCREASE. THE FLOW WILL REMAIN EASTERLY TODAY AND THAT WILL HELP
KEEP THE THREAT OF SHOWERS AND THUNDERSTORMS REACHING THE
LAKESHORE...WILL KEEP TOL, CLE AND ERI DRY. SOME QUESTION AS TO
THE TIMING OF THE SHOWERS AND THUNDERSTORMS...THE HRRR HAS SOME
SHOWERS AT 14Z NEAR FDY...THIS SEEMS TOO HIGH. THE THREAT OF
SHOWERS AND THUNDERSTORMS SHOULD DECREASE AROUND DARK.
.OUTLOOK...NON VFR POSSIBLE IN PRECIPITATION THROUGH WEDNESDAY.
&&
.MARINE...
A TRICKY LAKE FORECAST WITH THE BOUNDARY OVER CENTRAL OHIO AND HIGH
PRESSURE OVER LAKE ONTARIO. ALL THE MODELS AGREE THE WINDS WILL PICK
UP ON THE LAKE THIS AFTERNOON AND CONTINUE INTO THE EVENING. EARLY
THIS MORNING THE WINDS AND WAVES ARE CLOSE TO SMALL CRAFT ADVISORY
CONDITIONS ON THE WEST END OF THE LAKE. WILL GO WITH A SMALL CRAFT
ADVISORY ON THE WEST END FROM NOON TO MIDNIGHT. THE REST OF THE LAKE
WILL HAVE TO BE WATCHED.
THE WINDS WILL BE MAINLY SOUTHEAST SUNDAY AND BECOME SOUTHWEST FOR
MONDAY THROUGH THURSDAY. THE NEXT THREAT FOR A SMALL CRAFT ADVISORY
WILL BE LATE IN THE WORK WEEK AFTER A COLD FRONT MOVES THROUGH.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO MIDNIGHT EDT TONIGHT
FOR LEZ142>145.
&&
$$
SYNOPSIS...KOSARIK
NEAR TERM...KOSARIK
SHORT TERM...KOSARIK
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
404 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT ACROSS CENTRAL OHIO WILL DISSIPATE BY
MONDAY AS HIGH PRESSURE WILL HOLDS ALONG THE NEW ENGLAND COAST.
OUR FLOW WILL BECOME MORE SOUTHERLY AND MORE HUMID EARLY IN THE
WEEK AHEAD OF A COLD FRONT FROM THE WEST. THE FRONT SHOULD ARRIVE
LATER WEDNESDAY OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MOSTLY BETWEEN SYSTEMS THIS MORNING...WITH THE OVER RUNNING SYNOPTIC
CLOUDS AND A FEW SPRINKLES CLIPPING EASTERN LAKE ERIE AND AREAS EAST
OF PAINESVILLE. TO THE SOUTH THE OLD FRONTAL BOUNDARY IS NEAR
COLUMBUS.
THE ALTOCUMULUS ACROSS PARTS OF THE FORECAST AREA AND THE SPRINKLES
NEAR ERIE WILL THIN AND DISSIPATE EARLY THIS MORNING. THE OLD UPPER
LOW WELL TO OUR SOUTH WILL BEGIN TO LIFT OUT TO THE EAST-NORTHEAST
AND THE OLD FRONTAL BOUNDARY WILL SLOWLY BEGIN TO LIFT NORTH INTO
THE FORECAST AREA TODAY. NOT SURE HOW ACTIVE THE OLD FRONTAL
BOUNDARY WILL BECOME TODAY. THERE SHOULD BE WEAK SUBSIDENCE UNDER
THE BUILDING RIDGE ALOFT AND HIGH CLOUDS WILL SPREAD IN FROM THE
NORTHWEST LATE THIS MORNING. THIS COULD SUPPRESS CONVECTION. WILL
FORECAST RELATIVELY LOW POP...GENERALLY 10-35 PERCENT WITH THE
HIGHEST POP ACROSS THE SOUTH AND DRY (POP LESS THAN 15 PERCENT)
ALONG THE LAKE ERIE SHORE WHERE THE NORTHEAST FLOW OFF THE LAKE
SHOULD KEEP THINGS STABLE.
HIGH TEMPERATURES WILL BE SIMILAR TO YESTERDAY...PERHAPS A DEGREE
OR TWO COOLER AT INLAND LOCATIONS DUE TO THE INCREASE IN CLOUDS. A
COUPLE OF DEGREES WARMER NEAR LAKE ERIE WHERE THE WIND IS NOT OFF
THE WATER THIS MORNING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
AS THE DRY EAST-NORTHEAST FLOW BECOMES SOUTHERLY EARLY IN THE WEEK
WE WILL SEE INCREASINGLY HUMID CONDITIONS. THE OLD FRONTAL BOUNDARY
WILL LIFT NORTH OF THE AREA OR DISSIPATE ON MONDAY. INSTABILITY WILL
INCREASE BUT THERE IS NOT MUCH OF A TRIGGER FOR THUNDERSTORMS UNTIL
TUESDAY INTO WEDNESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE
WEST. WILL CONTINUE WITH A SMALL CHANCE OF SHOWERS/THUNDERSTORMS ON
MONDAY THEN A BETTER CHANCE OF SHOWERS/STORMS TUESDAY INTO
WEDNESDAY. FORECAST HIGHS WILL GENERALLY BE IN THE LOWER AND MID
80S. WITH ENOUGH SUN AND LACK OF SHOWERS COULD EVEN SEE UPPER 80S IN
A FEW LOCATIONS MONDAY OR TUESDAY. NOT AS WARM WEDNESDAY AS
SHOWERS/STORMS SHOULD BE MORE NUMEROUS BY THAT TIME.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
SOME ACTIVE WEATHER FOR THE PERIOD. THE MODELS ARE IN GENERAL
AGREEMENT WITH AN UPPER LOW MOVING ACROSS THE REGION THROUGH THE
PERIOD AND WITH A FRONT MOVING THROUGH THURSDAY AND THURSDAY NIGHT.
THE GFS KEEPS THE UPPER LOW ACROSS THE AREA FRIDAY WHILE THE GFS
MOVES THE LOW OUT. AT THIS TIME CONTINUING A GENERALLY DRY TREND
FRIDAY...EXCEPT KEPT 30 POPS OVER NW PA. USED A BLEND OF THE
GUIDANCE FOR THE TEMPERATURE FORECAST.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AN IMPULSE ALOFT WAS CAUSE SOME VIRGA OR LIGHT SHOWERS OVER NW PA
AND EASTERN LAKE ERIE EARLY THIS AM...THIS SHOULD DECREASE BY
DAYBREAK. A FRONTAL BOUNDARY WAS STILL WEST TO EAST ACROSS CENTRAL
OHIO. AT THIS TIME THE TEMPERATURE AND DEW POINT SPREAD IS FAIRLY
HIGH AND WITH SOME MID CLOUDS NOT EXPECTING AS MUCH FOG AS LAST
NIGHT. SOME 3SM IS POSSIBLE AT FAVORED LOCATIONS...WITH QUICK DISSIPATION.
OTHERWISE FOR TODAY THE BOUNDARY WILL SLOWLY SHIFT NE TODAY. THE
AIR MASS IS MOIST AT MID LEVELS AND THE LOW LEVEL MOISTURE WILL
INCREASE. THE FLOW WILL REMAIN EASTERLY TODAY AND THAT WILL HELP
KEEP THE THREAT OF SHOWERS AND THUNDERSTORMS REACHING THE
LAKESHORE...WILL KEEP TOL, CLE AND ERI DRY. SOME QUESTION AS TO
THE TIMING OF THE SHOWERS AND THUNDERSTORMS...THE HRRR HAS SOME
SHOWERS AT 14Z NEAR FDY...THIS SEEMS TOO HIGH. THE THREAT OF
SHOWERS AND THUNDERSTORMS SHOULD DECREASE AROUND DARK.
.OUTLOOK...NON VFR POSSIBLE IN PRECIPITATION THROUGH WEDNESDAY.
&&
.MARINE...
A TRICKY LAKE FORECAST WITH THE BOUNDARY OVER CENTRAL OHIO AND HIGH
PRESSURE OVER LAKE ONTARIO. ALL THE MODELS AGREE THE WINDS WILL PICK
UP ON THE LAKE THIS AFTERNOON AND CONTINUE INTO THE EVENING. EARLY
THIS MORNING THE WINDS AND WAVES ARE CLOSE TO SMALL CRAFT ADVISORY
CONDITIONS ON THE WEST END OF THE LAKE. WILL GO WITH A SMALL CRAFT
ADVISORY ON THE WEST END FROM NOON TO MIDNIGHT. THE REST OF THE LAKE
WILL HAVE TO BE WATCHED.
THE WINDS WILL BE MAINLY SOUTHEAST SUNDAY AND BECOME SOUTHWEST FOR
MONDAY THROUGH THURSDAY. THE NEXT THREAT FOR A SMALL CRAFT ADVISORY
WILL BE LATE IN THE WORK WEEK AFTER A COLD FRONT MOVES THROUGH.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO MIDNIGHT EDT TONIGHT
FOR LEZ142>145.
&&
$$
SYNOPSIS...KOSARIK
NEAR TERM...KOSARIK
SHORT TERM...KOSARIK
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
205 AM EDT SAT MAY 18 2013
.SYNOPSIS...
A FRONT ACROSS THE STATE OF OHIO FROM WEST TO EAST WILL REMAIN
NEARLY STATIONARY INTO SATURDAY AND THEN LIFT NORTH AS A WARM
FRONT AND BECOME QUITE DIFFUSE. HIGH PRESSURE WILL REMAIN OFF THE
EAST COAST OVER THE WEEKEND AND PRODUCE A SOUTHERLY FLOW ACROSS
THE REGION INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATED TO REMOVE THE MENTION OF SHOWERS OVER ALL BUT SW OF A MT
VERNON TO FINDLAY LINE. SHOWERS ACROSS CENTRAL OHIO COULD CREEP
INTO THE AREA FOR A BRIEF SHOWER OR TWO. REST OF THE FORECAST FOR
TONIGHT LOOKS REASONABLE.
ORIGINAL DISCUSSION...
A LONE SHOWER HAS DEVELOPED ALONG THE DEWPOINT GRADIENT THIS
AFTERNOON OVER RICHLAND COUNTY AND OTHER ENHANCED CU ARE ALIGNED
FARTHER WEST NEAR FDY. THERE IS SOME WEAK INSTABILITY ALONG AND
SOUTH OF THIS LINE SO WILL INCLUDE A SLIGHT CHANCE OF SHOWERS THIS
EVENING. HAVE USED THE MAV GUIDANCE FOR MIN TEMPERATURES WITH
MINOR CHANGES.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
A WARMER AND INCREASINGLY HUMID WEEKEND IS IN STORE FOR THE FORECAST
AREA AS THE FRONTAL BOUNDARY LIFTS NORTHWARD AND BECOMES DIFFUSE.
HIGHER HUMID WILL MOVE INTO THE REGION ESPECIALLY ON SUNDAY. A
WEAK SHORT WAVE WILL MOVE EAST ACROSS THE LOWER OHIO AND
TENNESSEE VALLEYS AND MAY SPREAD A FEW SHOWERS/STORMS INTO MAINLY
THE SOUTHERN COUNTIES ON SATURDAY AND SATURDAY EVENING BUT
CONFIDENCE AND TIMING IS RATHER UNCERTAIN.
WILL CONTINUE WITH A SLIGHT CHANCE OF SHOWERS/STORMS SUNDAY
AFTERNOON MAINLY OVER THE SOUTHEAST COUNTIES BUT FORCING FOR
ASCENT IS DIFFICULT TO DETERMINE AT THIS TIME SO WILL JUST
INCLUDE A SMALL TO SLIGHT CHANCE OF PCPN.
DRY CONDITIONS ARE EXPECTED SUNDAY NIGHT AND EARLY MONDAY. HAVE
CONTINUED WITH A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS FOR
MONDAY AFTERNOON BUT CONFIDENCE IS LOW.
HAVE USED THE MAV GUIDANCE FOR TEMPERATURES WITH MINOR CHANGES.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
THE EXTENDED PERIOD WILL BE DOMINATED BY A SURFACE LOW PRESSURE
CENTER JUST TO THE WEST OF THE FORECAST AREA. THIS SYSTEM WILL MOVE
SLOWLY TOWARDS THE REGION THROUGH THE WEEK. INITIALLY ON TUESDAY IT
APPEARS THAT MOST OF THE FORECAST AREA WILL BE IN THE WARM SECTOR AS
THE WARM FRONT WILL BE NORTH OF THE AREA. SHOWERS AND THUNDERSTORMS
ARE NOT OUT OF THE QUESTION IN THIS ENVIRONMENT BUT WITH A LACK OF A
KICKER...THE ACTIVITY SHOULD REMAIN SCATTERED. THE GFS SUGGESTS A
SHORT WAVE SHOULD ROTATE THROUGH THE AREA TUESDAY NIGHT BEFORE THE
ACTUAL COLD FRONT ON WEDNESDAY. WHILE ALL THE PERIODS NEXT WEEK
APPEAR TO BE UNSETTLED WEDNESDAY INTO WEDNESDAY NIGHT APPEAR TO BE
THE TWO PERIODS WITH THE BEST DYNAMICS AND THE GREATEST CHANCE OF
SHOWERS AND THUNDERSTORMS. SHOWERS WILL REMAIN ON THURSDAY AND
THURSDAY NIGHT AS THE LOW PRESSURE SYSTEM PULLS OUT OF THE AREA.
HIGH PRESSURE SHOULD BEGIN TO BUILD OVER THE REGION FRIDAY MORNING
AND SHOULD BRING AN END TO THE PRECIPITATION THREAT.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
AN IMPULSE ALOFT WAS CAUSE SOME VIRGA OR LIGHT SHOWERS OVER NW PA
AND EASTERN LAKE ERIE EARLY THIS AM...THIS SHOULD DECREASE BY
DAYBREAK. A FRONTAL BOUNDARY WAS STILL WEST TO EAST ACROSS CENTRAL
OHIO. AT THIS TIME THE TEMPERATURE AND DEW POINT SPREAD IS FAIRLY
HIGH AND WITH SOME MID CLOUDS NOT EXPECTING AS MUCH FOG AS LAST
NIGHT. SOME 3SM IS POSSIBLE AT FAVORED LOCATIONS...WITH QUICK DISSIPATION.
OTHERWISE FOR TODAY THE BOUNDARY WILL SLOWLY SHIFT NE TODAY. THE
AIRMASS IS MOIST AT MID LEVELS AND THE LOW LEVEL MOISTURE WILL
INCREASE. THE FLOW WILL REMAIN EASTERLY TODAY AND THAT WILL HELP
KEEP THE THREAT OF SHOWERS AND THUNDERSTORMS REACHING THE
LAKESHORE...WILL KEEP TOL, CLE AND ERI DRY. SOME QUESTION AS TO
THE TIMING OF THE SHOWERS AND THUNDERSTORMS...THE HRRR HAS SOME
SHOWERS AT 14Z NEAR FDY...THIS SEEMS TOO HIGH. THE THREAT OF
SHOWERS AND THUNDERSTORMS SHOULD DECREASE AROUND DARK.
.OUTLOOK...NON VFR POSSIBLE IN PRECIPITATION THROUGH WEDNESDAY.
&&
.MARINE...
A STALLED FRONTAL BOUNDARY REMAINS LOCKED INLAND KEEPING AN EAST TO
NORTHEAST WIND ACROSS LAKE ERIE TONIGHT. AN AREA OF LOW PRESSURE
MOVING INTO THE OHIO VALLEY SATURDAY AND AN AREA OF HIGH PRESSURE
OVER QUEBEC WILL KEEP AN EASTERLY DOMINANT FLOW OVER THE LAKE. THE
PRESSURE GRADIENT LOOKS UNIMPRESSIVE SO SPEEDS WILL LINGER AROUND
15KT. THE LOW PRESSURE SYSTEM WILL TURN THE WINDS TO THE SOUTHEAST
SATURDAY NIGHT AND INTO SUNDAY WITH SPEEDS UNDER 15 KT ON THE COOLER
WATER. THE FLOW WILL BECOME SOUTHWEST BY TUESDAY. SOME ISOLATED 4 FT
WAVES POSSIBLE IN THE WESTERN BASIN THROUGH SATURDAY...THEN WAVES
1-3 FT THROUGH THE REST OF THE FORECAST.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...LAPLANTE
NEAR TERM...DJB/LAPLANTE
SHORT TERM...LAPLANTE
LONG TERM...GARNET
AVIATION...KIELTYKA
MARINE...JAMISON
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1241 PM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1104 AM CDT SAT MAY 18 2013
GOING FORECAST IS IN GOOD SHAPE. INCREASED THE SKY COVER A BIT IN
OUR WESTERN AND NORTHERN ZONES THROUGH EARLY AFTERNOON AS VERY
LIGHT CONVECTION CONTINUES TO DIE IN THOSE AREAS. THIS MAY IMPACT
HIGH TEMPERATURES A LITTLE BIT. FOR NOW...SHAVED DOWN HIGHS AROUND
A CATEGORY THROUGHOUT THE NORTHWEST HALF OF OUR AREA AS
TEMPERATURES ARE STILL IN THE 60S TO AROUND 70 UNDERNEATH THE
CLOUD COVER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1236 PM CDT SAT MAY 18 2013
LOW PRESSURE WILL BE MEANDERING AROUND NORTH CENTRAL NEBRASKA AND
CENTRAL SOUTH DAKOTA THROUGH THE TAF PERIOD. THUNDERSTORM
DEVELOPMENT WILL BE LIKELY...WITH SEVERE WEATHER A THREAT...AS THE
EVENING PROGRESSES AND LASTING INTO LATE TONIGHT AND EARLY SUNDAY.
HOWEVER CONFIDENCE IS VERY LOW ON EXACT DETAILS AND TIMING ON HOW
THE CONVECTION WILL EVOLVE OVER TIME. FOR THE TAFS...TOOK A MODEL
BLEND OF THE NAM12...GEM REGIONAL AND GFS MODELS TO COME UP WITH
SOME TIMING OF THE CONVECTION IMPACTING THE AIRPORT SITES. BUT
AGAIN THIS WILL HAVE TO MONITORED CLOSELY. THE THUNDERSTORMS WILL
HAVE THE STRONG POTENTIAL TO SEND CONDITIONS DOWN INTO THE MVFR
RANGE...AND PROBABLY EVEN SOME SHORTER TERM IFR CONDITIONS WHERE
THE HEAVIER RAIN CELLS ARE. FURTHERMORE...THERE MAY EVEN BE SOME
IFR TO MVFR STRATUS SUNDAY MORNING IN THE RAIN COOLED AIR MASS...
ESPECIALLY EAST OF THE JAMES RIVER VALLEY. THE NAM HUMIDITY TIME
SECTIONS ARE STRONGLY HINTING AT THIS SCENARIO. BACKING UP CLOSER
TO THE NEAR TERM...WOULD NOT BE SURPRISED TO SEE SOME SHOWERS AND
ISOLATED THUNDERSTORMS IN NORTHWEST IOWA LATE THIS AFTERNOON AND
EARLY EVENING UNDER CUMULUS DEVELOPMENT.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJF
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...MJF
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1104 AM CDT SAT MAY 18 2013
.UPDATE...
ISSUED AT 1104 AM CDT SAT MAY 18 2013
GOING FORECAST IS IN GOOD SHAPE. INCREASED THE SKY COVER A BIT IN
OUR WESTERN AND NORTHERN ZONES THROUGH EARLY AFTERNOON AS VERY
LIGHT CONVECTION CONTINUES TO DIE IN THOSE AREAS. THIS MAY IMPACT
HIGH TEMPERATURES A LITTLE BIT. FOR NOW...SHAVED DOWN HIGHS AROUND
A CATEGORY THROUGHOUT THE NORTHWEST HALF OF OUR AREA AS
TEMPERATURES ARE STILL IN THE 60S TO AROUND 70 UNDERNEATH THE
CLOUD COVER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 627 AM CDT SAT MAY 18 2013
SHOWERS AND THUNDERSTORMS IN SOUTH CENTRAL SD EXPECTED TO DIMINISH BY
AROUND 15Z. COULD SEE A FEW GUSTS TO AROUND 35KT WITH THUNDERSTORMS
IN THE KHON AREA THIS MORNING. ALSO WATCHING A BAND OF MVFR STRATUS
ACROSS WESTERN AND CENTRAL NEBRASKA WHICH IS SPREADING NORTHEAST THIS
MORNING. EXPECT THIS BAND TO LARGELY DISSIPATE THROUGH MID/LATE
MORNING AS IT APPROACHES IT MISSOURI VALLEY...WITH LITTLE TO NO IMPACT
IN OUR FORECAST AREA. OTHERWISE...EXPECT SHOWERS AND STORMS TO PUSH
IN SOUTH CENTRAL SD AFTER 00Z AND BECOME MORE WIDESPREAD AND THEY
TRACK EAST INTO THE I29 CORRIDOR AROUND 06Z. STRONG TO SEVERE STORMS
WILL BE POSSIBLE THIS EVENING AND OVERNIGHT WITH LARGE HAIL...GUSTS
TO 70 MPH POSSIBLE. BEST THREAT FOR LARGE HAIL WILL OCCUR FROM 00Z TO
06Z AND MAY TRANSITION TO MORE A DAMAGING WIND THREAT LATE EVENING
AND OVERNIGHT. MVFR/IFR CEILINGS POSSIBLE IN STRONGER STORMS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...MJF
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
639 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 627 AM CDT SAT MAY 18 2013
SHOWERS AND THUNDERSTORMS IN SOUTH CENTRAL SD EXPECTED TO DIMINISH BY
AROUND 15Z. COULD SEE A FEW GUSTS TO AROUND 35KT WITH THUNDERSTORMS
IN THE KHON AREA THIS MORNING. ALSO WATCHING A BAND OF MVFR STRATUS
ACROSS WESTERN AND CENTRAL NEBRASKA WHICH IS SPREADING NORTHEAST THIS
MORNING. EXPECT THIS BAND TO LARGELY DISSIPATE THROUGH MID/LATE
MORNING AS IT APPROACHES IT MISSOURI VALLEY...WITH LITTLE TO NO IMPACT
IN OUR FORECAST AREA. OTHERWISE...EXPECT SHOWERS AND STORMS TO PUSH
IN SOUTH CENTRAL SD AFTER 00Z AND BECOME MORE WIDESPREAD AND THEY
TRACK EAST INTO THE I29 CORRIDOR AROUND 06Z. STRONG TO SEVERE STORMS
WILL BE POSSIBLE THIS EVENING AND OVERNIGHT WITH LARGE HAIL...GUSTS
TO 70 MPH POSSIBLE. BEST THREAT FOR LARGE HAIL WILL OCCUR FROM 00Z TO
06Z AND MAY TRANSITION TO MORE A DAMAGING WIND THREAT LATE EVENING
AND OVERNIGHT. MVFR/IFR CEILINGS POSSIBLE IN STRONGER STORMS.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
442 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 338 AM CDT SAT MAY 18 2013
UNSTABLE CONDITIONS AGAIN ON TAP TODAY FOR THE REGION. BREEZY
SOUTHERLY LATE MORNING AND AFTERNOON WILL CONTINUE TAPPING INTO
PLENTY OF MOISTURE AND SHOULD HOLD DEWPOINTS AROUND THE 60 DEGREE
MARK THROUGHOUT THE FORECAST AREA. ALTHOUGH WE SHOULD SEE SOME
RESIDUAL CLOUDS FROM OVERNIGHT CONVECTION LINGER THIS MORNING...WE
SHOULD SEE ENOUGH AFTERNOON SUNSHINE FOR TEMPERATURES TO EASILY
WARM INTO THE 80S. SHEAR LOOKS PRETTY MODEST INTO THE
AFTERNOON...HOWEVER LAPSE RATES AND CAPE VALUES INCREASE
SIGNIFICANTLY THROUGH THE DAY. WITH THE TROUGH JUST BEGINNING TO
MOVE OUT OF THE ROCKIES TODAY AND SURFACE CONVERGENCE LIKELY REMAIN
OUTSIDE OF THE FORECAST AREA...CONVECTION SEEMS UNLIKELY FOR OUR
FORECAST AREA WITH STRONG CAPPING IN PLACE. HAVE REMOVED
PRECIPITATION CHANCES FOR TODAY WITH THE EXCEPTION OF A SLIGHT
CHANCE IN OUR EXTREME WESTERN COUNTIES LATE AFTERNOON. /
HEADING INTO THE EVENING HOURS...LIKELY THAT THE WARMER TEMPS
ALOFT WILL PROVIDE JUST ENOUGH CAPPING FOR MOST OF THE WARM SECTOR
TO RELEGATE THE CONVECTIVE THREAT FOR THE EARLY EVENING TO
GENERALLY THE JAMES VALLEY AND WEST...CLOSER TO LOCATION OF THE
LOW LEVEL BOUNDARY AND ANY RESIDUAL OUTFLOWS FROM EARLIER DAY
ACTIVITY. RAP AND TO LESSER DEGREE GFS INDICATE THAT MAY BE AS
MUCH AS 100-150 J/KG LID OVER THE FAIRLY MOIST SURFACE MIXED
LAYER. ABOVE...A VERY UNSTABLE ELEVATED MIXED LAYER...WHICH WILL
SET UP AN ATMOSPHERE WITH 1250-1750 J/KG INSTABILITY IN RESERVE.
LIKELY THAT COVERAGE OF STORMS MAY BE SOMEWHAT LESSER UNTIL LATE
EVENING AND EARLY IN THE OVERNIGHT...WHEN SHOULD FINALLY START TO
FEEL IMPACT OF WAVE CURRENTLY SWINGING THROUGH THE DESERT
SOUTHWEST. ANY MORE SCATTERED DEVELOPMENT JAMES VALLEY AND WEST IN
THE EVENING...EVEN SOMEWHAT ELEVATED...WOULD CERTAINLY HAVE ENOUGH
EFFECTIVE SHEAR OF 25 TO 35 KNOTS IN ORDER TO ORGANIZE AND PRESENT
A THREAT FOR ISOLATED SEVERE STORMS WITH HAIL UP TO TWO INCHES...
DAMAGING WIND GUSTS...AND A TORNADIC THREAT NEAR DISCERNIBLE
BOUNDARIES...ESPECIALLY AS SHEAR INCREASES WITH STRENGTHENING LOW
LEVEL JET EARLY THIS EVENING. THE INCREASE IN LOW LEVEL 0-3KM
SHEAR STRONGLY SUGGESTING THAT WILL GET SOME UPSCALE ORGANIZATION
AND DEVELOPMENT OF BOWING SEGMENTS IN THE OVERNIGHT HOURS...
PERHAPS A FAIRLY WIDESPREAD DAMAGING WIND EVENT WITH GRADUALLY
LESSER HAIL POTENTIAL THROUGH 08-09Z AS DEVELOPMENT IN NEBRASKA
STREAMS NORTHEASTWARD IN TANDEM WITH UPPER FORCING PULSE. MUCH
MORE COHERENT BAND OF THUNDERSTORMS WILL SWING EASTWARD OVERNIGHT...
WITH SEVERE WEATHER THREAT DIMINISHING AFTER 08-09Z. SOME AREAS
OF HEAVY RAINFALL OVER THE PAST COUPLE OF DAYS WILL HEIGHTEN
CONCERNS SOMEWHAT OF FLASH FLOODING...WITH SOME AREAS OF 1 TO 1.5
INCH PER HOUR /1.5 TO 2 INCHES PER 3 HOUR/ THRESHOLDS ALONG AND
EAST OF I29.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 338 AM CDT SAT MAY 18 2013
EXPECT TO SEE AN EXIT EARLY IN THE DAY OF THE MAIN CONVECTIVE BAND...
WITH LEADING WAVE ALONG BOUNDARY LIFTING NORTHWARD...AND SYNOPTIC
NORTH/SOUTH BOUNDARY DRIFTING THROUGH AREAS BETWEEN THE JAMES
VALLEY AND I29 THROUGH THE DAY. DEEP TROUGH WILL START TO SWING
NEGATIVE TILT ENERGY AROUND THE BASE AND INTO THE REGION IN THE
18Z-21Z TIME FRAME. NOT NEARLY AS CAPPED FOR THIS TIME AROUND...
AND SHOULD INITIATE STORMS ALONG ANY BOUNDARIES QUITE A BIT
EARLIER IN THE DAY...PERHAPS AS EARLY AS 18Z-20Z ACROSS EASTERN
NEBRASKA WHERE IT SOMEWHAT MORE UNSTABLE AND WILL FIND THE LIFT
APPROACHING SOONER. MODEL BASED DEEP BULK SHEAR OF 30 TO 35 KNOTS
IN PLACE...AND 0-3KM SHEAR OF 20 TO 25 KNOTS IS VERY INDICATIVE OF
ORGANIZATION AND SUPERCELL POTENTIAL. THERE ARE A LOT OF QUESTIONS
REGARDING THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT TONIGHT TO
REDISTRIBUTE THE THREAT AREA. HOWEVER...AT THIS TIME...WOULD
APPEAR THAT LOCATIONS FROM JUST WEST OF I 29 EASTWARD WOULD HAVE
THE GREATEST THREAT FOR SEVERE STORMS...INCLUDING THE RISK OF LARGE
HAIL AND ISOLATED TORNADOES...ESPECIALLY THE LOWER MISSOURI VALLEY
EASTWARD INTO NORTHWEST IOWA...TRANSITIONING TOWARD A GRADUALLY LESSER
HAIL AND GREATER WIND THREAT FARTHER EASTWARD THROUGH NORTHWEST
IOWA...WITH THE THREAT LASTING THROUGH EARLY EVENING.
ON SUNDAY NIGHT...NEGATIVE TILT ENERGY SWINGING NORTHWARD WILL
START TO CLOSE OFF THE MID LEVEL TROUGH OVER NEBRASKA AND SOUTH
DAKOTA...AND IT WILL BE A LONG AND DRAWN OUT PROCESS TO FINALLY
RID OURSELVES OF THIS FEATURE THROUGH MIDWEEK. THIS SPELLS OUT
AN UNSETTLED PERIOD WITH WAVES OF SCATTERED TO FAIRLY WIDESPREAD
SHOWERS AND A FEW THUNDERSTORMS. FAIRLY MOIST NEUTRAL BY TUESDAY...
AND GRADUALLY LIMITED THE ISOLATED THUNDER MENTION TOWARD THE EAST.
WILL HAVE TO MONITOR THE THREAT FOR SPIN UP GIVEN THE PROXIMITY OF
THE CLOSED LOW ON MONDAY...AND EVEN IN THE EAST ON TUESDAY...BUT
MUCH WILL DEPEND ON BEING ABLE TO BREAK OUT OF THE CLOUDS AND MORE
WIDESPREAD PRECIPITATION...AND GENERATE A DECENT SURFACE BASED
LAPSE RATE DURING EACH DIURNAL CYCLE.
GRADUALLY...WILL SEE A DECREASING AND MORE DIURNAL THREAT OF
SHOWERS BY WEDNESDAY... STILL WITH THE AREA UNDER INFLUENCE OF
CYCLONIC FLOW AS UPPER LOW WOBBLES AWAY THROUGH IOWA. END OF THE
WEEK DID FINALLY OPEN UP THE DIURNAL RANGES A BIT MORE WITH IMPACT
OF DRIER EASTERLY FLOW FROM KEEWATIN HIGH.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1112 PM CDT FRI MAY 17 2013
VFR EXPECTED THROUGH THE MAJORITY OF THE TAF PD. THUNDERSTORM
CHANCES RETURN IN THE FINAL FEW HOURS OF THE TAF PD.
LINE OF TSRA WAS OVER HON WITH -RA LINGERING FOR A WHILE AFTER WITH
NO SIGNIFICANT RESTRICTION TO VISIBILITY IN -RA. AFTER THE RAIN
CLEARS NSW THROUGH MOST OF THE REST OF THE HON TAF PD.
SOUTH/SOUTHEAST WIND WILL REMAIN AOA 10KTS AT FSD/SUX THROUGH THE
NIGHT SO HAVE REMOVED PREVIOUS MENTION OF FOG. WIND WONT SHIFT MUCH
IN DIRECTION THRU THE DAY ON SATURDAY BUT SPEED WILL INCREASE WITH
AFTERNOON GUSTS EXPECTED.
IN THE LATTER PART OF THE TAF PD IN THE 02-06Z TIME FRAME...SEVERE
THUNDERSTORMS WILL BE POSSIBLE MOSTLY INVOF FSD/SUX WITH DAMAGING
HAIL AND WIND THE MAIN THREATS. WILL ADD SOME TSRA AT THAT TIME BUT
CONFIDENCE IS ONLY MEDIUM AS FAR AS TIMING AND LOCATION.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...CHAPMAN/
LONG TERM...CHAPMAN
AVIATION...SALLY
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1222 AM CDT SAT MAY 18 2013
.UPDATE...
AVIATION DISCUSSION HAS BEEN UPDATED.
NOT MUCH CHANGE IN THE FORECAST FOR THE TIME BEING. THUNDERSTORMS
HAVE FORMED OVER THE CENTRAL PORTION OF THE STATE AND ARE MOVING
NORTHEAST. STILL EXPECT SOME INCREASE IN COVERAGE AS THE LLJ GETS
CRANKED UP A BIT LATER TNT. HOWEVER QUESTIONABLE WHETHER THERE
WILL BE MUCH IN THE WAY OF SVR THE REST OF THE NIGHT. PERHAPS AN
ELEVATED HAILER OR TWO.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT
THE MODELS ALL AGREE WELL AND CONTINUE TO BE VERY CONSISTENT AT
BRINGING THE UPPER LEVEL LOW PRESSURE TROUGH OUT OF THE SOUTHWEST
US THROUGH SUNDAY NIGHT AND CLOSING IT OFF. THUNDERSTORMS ARE
BEGINNING TO DEVELOP IN WESTERN SOUTH DAKOTA LATE THIS AFTERNOON
AND WILL CONTINUE TO DEVELOP AND MOVE EAST INTO CENTRAL AND NORTH
CENTRAL SOUTH DAKOTA THROUGH THE EVENING. THE HRRR MODEL SHOWS
THIS DEVELOPMENT VERY WELL. AS THE LLJ INCREASES INTO THE EVENING
HOURS...EXPECT THIS TREND TO CONTINUE. WITH INSTABILITY INCREASING
ALONG WITH DEEP LAYER SHEAR...SOME SEVERE STORMS ARE POSSIBLE
MAINLY WEST OF THE JAMES VALLEY TONIGHT. THIS FIRST WAVE WILL MOVE
THROUGH WITH MORE DEVELOPMENT EXPECTED SATURDAY AFTERNOON AND
EVENING ACROSS THE CWA. HIGH INSTABILITY WILL BUILD UP AGAIN
SATURDAY AFTERNOON AND EVENING ACROSS THE CWA WHILE ANOTHER SHORT
WAVE TROUGH KICKS OUT OF THE SOUTHWEST UPPER TROUGH. THIS
INTERACTION ALONG A GOOD LOW LEVEL SURFACE BOUNDARY/WARM FRONT ON
SATURDAY AFTERNOON AND EVENING WILL RESULT IN NUMEROUS SHOWERS AND
THUNDERSTORMS AGAIN. SEVERE STORMS LOOK LIKE A GOOD POSSIBILITY
ON SATURDAY AFTERNOON AND EVENING. AS THE MAIN UPPER LEVEL TROUGH
LIFTS INTO THE REGION SUNDAY AND SUNDAY NIGHT AND CLOSES
OFF...SHOWER AND THUNDERSTORM POSSIBILITIES WILL CONTINUE TO BE
VERY GOOD ACROSS ALL OF THE CWA. HEAVY RAIN WILL ALSO BE A THREAT
ACROSS THE CWA AS HIGH PRECIPITABLE WATERS WILL BE AVAILABLE FOR
STORMS.
.LONG TERM...MONDAY THROUGH FRIDAY
DECENT AGREEMENT EXISTS BETWEEN DETERMINISTIC GUIDANCE TO START
THINGS OFF WITH A NEARLY STATIONARY UPPER LOW OVER THE EASTERN
DAKOTAS/MINNESOTA. THIS FEATURE WILL DRIFT SLOWLY TO THE
EAST...WITH WRAP AROUND MOISTURE AND WEAK INSTABILITY LEADING TO
CONSTANT WIDESPREAD SHOWER ACTIVITY...WHICH WILL ALSO RESULT IN
TEMPERATURES BELOW NORMAL FOR MUCH OF THE EXTENDED. ONCE THE UPPER
LOW PUSHES EAST...A COL AREA FORMS OVERHEAD...WITH WEAK
SOUTHEASTERLY LOW LEVEL RETURN FLOW DEVELOPING FOR THE END OF THE
PERIOD...WITH MILDER TEMPERATURES AND LIKELY DRY CONDITIONS.
&&
.AVIATION...
06Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
A LINE OF STORMS IS IMPACTING KABR/KATY. ANOTHER AREA OF STORMS TO
THE WEST MAY AFFECT KMBG TONIGHT AS WELL. WINDS WILL ALSO BE
GUSTY IN AND AROUND THUNDERSTORMS. CONDITIONS ARE EXPECTED TO BE
MAINLY VFR...WITH PERHAPS SOME MVFR CIGS DEVELOPING IN THE MORNING
BEHIND THE STORMS. ANOTHER ROUND OF TSTORMS IS EXPECTED SAT
EVENING.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...TDK
SHORT TERM...MOHR
LONG TERM...CONNELLY
AVIATION...SD
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
152 PM CDT SAT MAY 18 2013
.UPDATE...FOR 18Z TAFS.
&&
.AVIATION...
LOW-LEVEL MOISTURE AND A SFC/LOW-LEVEL BOUNDARY EXPECTED TO
REMAIN IN THE IMMEDIATE VICINITY THE NEXT 24HRS. THAT WILL
CONTINUE TREND OF PERIODIC SHOWERS/STORMS. ADDITIONALLY...
CEILINGS/VSBYS EXPECTED TO DROP INTO MVFR/IFR RANGE TONIGHT
...ESPECIALLY CSV WHERE MOISTURE DEEPER AND CONVECTION EXPECTED
TO BE MORE NUMEROUS. IMPROVEMENT WILL OCCUR LATE SUN MORNING.
&&
.PREV DISCUSSION... /ISSUED 1131 AM CDT SAT MAY 18 2013/
MESOSCALE UPDATE...CELLS ARE NOW STARTING TO DEVELOP MAINLY EAST
OF I-65, WHERE LOW-LEVEL MOISTURE IS A LITTLE MORE PLENTIFUL. LAPS
SOUNDING FOR BNA VALID AT 15Z ALREADY SHOWS A LIFTED INDEX OF -3.6
AND A CONVECTIVE AVAILABLE POTENTIAL ENERGY OF 1896 J/KG. K-INDEX
IS A LITTLE LOW AT JUST 23, OWING MAINLY TO DRY AIR ABOVE ABOUT
850 MB. NAM SHOWS THE UPPER TROUGH SITUATED JUST EAST OF MIDDLE
TENNESSEE, WITH A RIDGE OF HIGH PRESSURE WEST OF THE MISSISSIPPI,
PLACING THE MID STATE UNDER A NW FLOW ALOFT, WHICH SHOULD HELP
FURTHER STEEPEN OUR MID-LEVEL LAPSE RATES. RUC MODEL SOUNDINGS FOR
THIS AFTERNOON SHOW THE LI DROPPING TO BETWEEN -5 AND -6, WITH
CAPES EXCEEDING 2500 J/KG DURING THE MOST UNSTABLE PARTS OF THE
DAY. FULLY EXPECT CONVECTION TO CONTINUE DEVELOPING. CURRENT
FORECAST OF LIKELY POP`S ALONG AND JUST WEST OF THE PLATEAU, WITH
SCATTERED POP`S ELSEWHERE, APPEARS TO BE JUSTIFIED. SPC IS KEEPING
MIDDLE TENNESSEE UNDER GENERAL THUNDERSTORMS. BELIEVE MOST
AFTERNOON STORMS WILL BE STRONG AT MOST, ALTHOUGH ISOLATED SEVERE
STORMS CERTAINLY CAN`T BE RULED OUT.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
07
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1131 AM CDT SAT MAY 18 2013
.MESOSCALE UPDATE...CELLS ARE NOW STARTING TO DEVELOP MAINLY EAST
OF I-65, WHERE LOW-LEVEL MOISTURE IS A LITTLE MORE PLENTIFUL. LAPS
SOUNDING FOR BNA VALID AT 15Z ALREADY SHOWS A LIFTED INDEX OF -3.6
AND A CONVECTIVE AVAILABLE POTENTIAL ENERGY OF 1896 J/KG. K-INDEX
IS A LITTLE LOW AT JUST 23, OWING MAINLY TO DRY AIR ABOVE ABOUT
850 MB. NAM SHOWS THE UPPER TROUGH SITUATED JUST EAST OF MIDDLE
TENNESSEE, WITH A RIDGE OF HIGH PRESSURE WEST OF THE MISSISSIPPI,
PLACING THE MID STATE UNDER A NW FLOW ALOFT, WHICH SHOULD HELP
FURTHER STEEPEN OUR MID-LEVEL LAPSE RATES. RUC MODEL SOUNDINGS FOR
THIS AFTERNOON SHOW THE LI DROPPING TO BETWEEN -5 AND -6, WITH
CAPES EXCEEDING 2500 J/KG DURING THE MOST UNSTABLE PARTS OF THE
DAY. FULLY EXPECT CONVECTION TO CONTINUE DEVELOPING. CURRENT
FORECAST OF LIKELY POP`S ALONG AND JUST WEST OF THE PLATEAU, WITH
SCATTERED POP`S ELSEWHERE, APPEARS TO BE JUSTIFIED. SPC IS KEEPING
MIDDLE TENNESSEE UNDER GENERAL THUNDERSTORMS. BELIEVE MOST
AFTERNOON STORMS WILL BE STRONG AT MOST, ALTHOUGH ISOLATED SEVERE
STORMS CERTAINLY CAN`T BE RULED OUT.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
718 PM CDT SUN MAY 19 2013
.AVIATION...
FOR THE 00Z TAFS...THUNDERSTORM CHANCES AND TIMING THE ONSET OF
MVFR STRATUS ARE THE PRIMARY FORECAST CONCERNS THROUGH THE VALID
FORECAST PERIOD.
THUNDERSTORM CHANCES...WENT AHEAD AND LEFT THUNDERSTORMS OUT OF
THE METROPLEX AREA TAFS FOR THIS EVENING BASED LARGELY ON
SATELLITE OBSERVATIONS. THE LATEST RAP FORECAST SOUNDINGS
INDICATED THAT THE CAP OVER THE DFW AREA WOULD ERODE BY 02Z
POSSIBLY RESULTING IN THUNDERSTORMS NEAR AREA TAF SITES. VISIBLE
SATELLITE IMAGERY INDICATES FLAT CUMULUS CLOUDS WHILE IR SATELLITE
IMAGES SHOW CLOUD TOP TEMPERATURES HOLDING STEADY AT THE TIME OF
THIS DISCUSSION. EARLY RESULTS FROM THE 00Z FWD RAOB INDICATE A
SUBSTANTIAL CAP REMAINS IN PLACE OVER THE METROPLEX...HOWEVER AN
AIRCRAFT SOUNDING TAKING OFF FROM KDAL DID INDICATE A WEAKER CAP.
EITHER WAY...A CAP REMAINS IN PLACE AND IN THE ABSENCE OF STRONG
LIFT...DO NOT SEE A REASON FOR STORMS TO INITIATE NEAR AREA TAF
SITES THIS EVENING OR OVERNIGHT.
FOR TOMORROW...AN UPPER LEVEL DISTURBANCE OVER UTAH IS EXPECTED TO
MOVE TOWARDS THE REGION OVER THE NEXT 24 TO 36 HRS. THIS WILL
RESULT IN BETTER UPPER LEVEL SUPPORT AND LIFT ALONG THE DRYLINE BY
LATE TOMORROW AFTERNOON RESULTING IN A HIGHER CONFIDENCE FORECAST
FOR THUNDERSTORMS. STORMS THAT DEVELOP ALONG THE DRYLINE WOULD
LIKELY NOT REACH THE METROPLEX UNTIL AFTER 23Z OR 6 PM CDT. WENT
AHEAD WITH A MENTION OF VCTS IN ALL METROPLEX AREA TAFS AFTER THIS
TIME DUE TO THE HIGHER CONFIDENCE IN THE CLOSE PROXIMITY OF
STORMS. A CAPPING INVERSION IS EXPECTED TO REMAIN IN PLACE OVER
THE METROPLEX TOMORROW AFTERNOON...SO ITS DIFFICULT TO KNOW
WHETHER STORMS WILL BE ABLE TO OVERCOME THIS CAP OR NOT TO MOVE
DIRECTLY OVER AREA TAF SITES. EITHER WAY...THE STORMS ARE EXPECTED
TO BE CLOSE ENOUGH TO CAUSE TRAFFIC HEADACHES AT AREA AIRPORTS SO
THE VCTS IS IN THE FORECAST FOR PLANNING PURPOSES MORE THAN
ANYTHING ELSE AT THIS POINT.
MVFR STRATUS...NO CHANGES MADE TO THE PREVIOUS FORECAST. WE WILL
ONCE AGAIN HAVE A STRONG LOW-LEVEL JET OF 50 KTS OR GREATER OVER
NORTH TX TONIGHT. THIS SHOULD RESULT IN A SIMILAR STRATUS TIMING
TO THIS MORNING WHERE STRATUS BUILT OVER METROPLEX TAF SITES AFTER
11Z. STRATUS SHOULD SCATTER OUT OR LIFT TO VFR LEVELS QUICKLY WITH
DRIER AIR ABOVE THE STRATUS DECK ABOVE THE CAP.
CAVANAUGH
&&
.PREV DISCUSSION... /ISSUED 328 PM CDT SUN MAY 19 2013/
THE DRYLINE HAS REACHED A LINE FROM WICHITA FALLS TO GRAHAM TO
BROWNWOOD WHERE IT WILL LIKELY STALL BEFORE RETREATING WEST THIS
EVENING. THE MAIN FORECAST CONCERN THROUGH THIS EVENING IS
WHETHER STORMS WILL INITIATE ALONG THE DRYLINE AND THE AMOUNT OF
COVERAGE. AS DISCUSSED IN THE MORNING UPDATE...MOST OF THE MODEL
GUIDANCE IS NOT INITIATING ANY CONVECTION IN OUR REGION THIS
EVENING DESPITE CIN BECOMING ALMOST NEGLIGIBLE ACROSS THE WESTERN
ZONES. HOWEVER THE RUC/HRRR/GFS HAVE NOT WAVERED AND ONE OF THE
HI-RES WRFS AT 12Z HAS NOW JOINED THE INITIATION CAMP. THE ISSUE
AT HAND IS LIKELY THAT TODAY/S STRONG WINDS AND DRY AIR ALOFT WILL
MAKE IT TOUGH FOR AN INFANT UPDRAFT TO BECOME ESTABLISHED AND
GROW INTO A SUPERCELL WITHOUT A SHORTWAVE TO AID IN LIFT. RIGHT
NOW THE BEST GUESS IS THAT 1 TO 3 STORMS WILL MANAGE TO DEVELOP
OVER THE WESTERN CWA BY EARLY EVENING...AND WILL CONTINUE THE
FORECAST OF 20-30 POPS WEST OF A LINE FROM SHERMAN TO DFW TO
LAMPASAS. LOCAL OBJECTIVE ANALYSIS INDICATES CAPE VALUES ARE FROM
2000-3000 J/KG OVER THE CWA AND AMPLE DEEP LAYER SHEAR EXISTS TO
SUPPORT VERY LARGE HAIL AND DAMAGING WINDS. AN ISOLATED TORNADO
WILL BE POSSIBLE BETWEEN 6 AND 8 PM WHEN LOW LEVEL WIND SHEAR
RAMPS UP JUST BEFORE THE SURFACE AIRMASS BECOMES TOO NEGATIVELY
BUOYANT WITH LOSS OF HEATING. STORMS MAY HOLD TOGETHER LONG ENOUGH
TO AFFECT LOCATIONS FARTHER TO THE EAST BY MID-LATE
EVENING...ESPECIALLY NORTH OF I-20...BUT SEVERE WEATHER POTENTIAL
WILL BE DIMINISHING. OTHERWISE A BREEZY AND MUGGY NIGHT IS IN
STORE FOR THE REGION.
THE STORM THREAT FOR MONDAY IS LOOKING GREATER ACROSS A LARGER
PART OF NORTH TEXAS. THE CIN WILL BE EVEN WEAKER THAN TODAY AND
ALMOST ALL OF THE MODELS ARE INDICATING STORM INITIATION IN THE
CWA. THE DRYLINE WILL BE ROUGHLY IN THE SAME LOCATION AS IT IS
TODAY. THE GFS AND NAM ARE MOST AGGRESSIVE WITH HEIGHT FALLS AND
CONVECTION ACROSS THE NW CWA...WHICH RAISES CONFIDENCE THAT THIS
AREA WILL LIKELY SEE SUPERCELL STORMS AND SEVERE WEATHER. EXPECT
SEVERAL SUPERCELLS TO DEVELOP ACROSS THE WESTERN ZONES...INCLUDING
SOME ISOLATED CELLS ACROSS THE SW ZONES. VERY HIGH INSTABILITY
AND AMPLE DEEP LAYER SHEAR WILL SUPPORT A THREAT OF SIGNIFICANT
SEVERE WEATHER INCLUDING GIANT HAIL...DAMAGING WINDS AND A FEW
TORNADOES. LOW LEVEL WIND SHEAR GETS STRONGER AFTER 7PM WITH 0-3KM
SRH VALUES ABOVE 300 M2/S2. SINCE THERE IS LESS CIN THERE IS MORE
TIME FOR EVENING SUPERCELLS TO TAP INTO THIS INSTABILITY AFTER
DARK WHICH IS WHAT IS RAISING OUR CONCERN FOR TORNADOES. HAVE
BUMPED UP POPS TO 30-50 PERCENT IN THE WESTERN ZONES...AND
RAISED THEM FOR THE CENTRAL AND NORTHEAST ZONES AS WELL...AS
SUPERCELLS WILL HEAD EASTWARD AND HOLD TOGETHER LONGER.
ON TUESDAY A WEAK COLD FRONT WILL BECOME DRAPED ACROSS THE CWA
FROM ROUGHLY PARIS TO DFW TO EASTLAND. HIGH TEMPS WILL BE A LITTLE
COOLER THIS DAY...BUT INSTABILITY WILL STILL BE VERY HIGH
ESPECIALLY ACROSS THE SOUTHERN ZONES. ALL MODEL GUIDANCE SHOWS
STRONG UPPER LEVEL FORCING OVER NORTH TEXAS TUESDAY AFTERNOON AS
THE TROUGH AXIS SWINGS THROUGH THE AREA. THIS WILL SET THE STAGE
FOR SCATTERED TO NUMEROUS SHOWERS AND STORMS THAT WILL LIKELY
DEVELOP ALONG THE FRONT TUESDAY AFTERNOON AND MOVE EAST AND
SOUTHEAST INTO THE NIGHTTIME HOURS. SINCE LOW LEVEL WIND FIELDS
RELAX A BIT...THESE STORMS MAY TEND TO ORGANIZE INTO A MCS/SQUALL
LINE OVER THE CENTRAL ZONES. OBVIOUSLY A SEVERE WEATHER THREAT
WILL EXIST WITH THIS CONVECTIVE EPISODE AS WELL. RAINFALL WILL
RANGE FROM A TRACE IN THE NW TO 1.5 INCHES IN THE SOUTHEAST ZONES.
EXPECT THIS CONVECTIVE EPISODE TO FINALLY EXHAUST THE ATMOSPHERE
AND PUSH THE BEST MOISTURE AND INSTABILITY SOUTHEAST OF THE AREA
BY WEDNESDAY MORNING. WILL KEEP WEDNESDAY DRY.
WEAK RIDGING SETS UP OVER THE AREA WEDNESDAY AND INTO NEXT
WEEKEND. SOUTHEAST WINDS WILL CONTINUE WHICH WILL KEEP LOW TEMPS
IN THE MID 60S TO NEAR 70...AND HIGHS IN THE MID 80S TO NEAR 90
EACH DAY. CONVECTION IS EXPECTED TO OCCUR OVER THE HIGH PLAINS
THURSDAY AND FRIDAY...AND WITH A SOUTHEASTERLY FLOW IN THE LOWEST
800MB WE WILL NEED TO KEEP AN EYE ON SOME OF THIS ACTIVITY MAKING
A RUN AT THE CWA DURING THE OVERNIGHT HOURS. SINCE THERE IS A LACK
OF STRONG NORTHWEST FLOW ALOFT IN THE MID LEVELS...BELIEVE
CONVECTION WILL DISSIPATE BEFORE REACHING MOST OF THE AREA...BUT
HAVE INSERTED A SLIGHT CHANCE IN THE NW ZONES THURSDAY AND FRIDAY
NIGHTS. WILL KEEP THE REMAINDER OF THE FORECAST DRY.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 90 71 88 67 / 10 20 40 50 50
WACO, TX 72 90 72 91 68 / 5 10 20 40 60
PARIS, TX 70 87 69 83 65 / 10 10 60 50 50
DENTON, TX 70 89 69 86 64 / 10 30 40 40 40
MCKINNEY, TX 70 89 70 85 65 / 10 20 40 50 50
DALLAS, TX 73 91 73 89 69 / 10 20 40 50 50
TERRELL, TX 70 89 71 87 68 / 10 10 30 50 60
CORSICANA, TX 71 89 72 88 69 / 5 10 20 40 60
TEMPLE, TX 71 90 72 92 69 / 5 10 20 40 60
MINERAL WELLS, TX 70 94 68 88 65 / 20 30 30 40 40
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1237 PM CDT SAT MAY 18 2013
.DISCUSSION...
SEE AVIATION DISCUSSION BELOW.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS MUCH OF THE AREA. JUNCTION
MAINTAINS MVFR VISIBILITY...THOUGH AS WINDS HAVE PICKED UP ACROSS
WEST CENTRAL TEXAS DUE TO A TIGHT SURFACE PRESSURE GRADIENT...THE
HAZE WILL MIX OUT. WINDS WILL DROP OFF EARLY THIS EVENING AS THE
PRESSURE GRADIENT RELAXES. ISOLATED THUNDERSTORMS ARE POSSIBLE
THIS AFTERNOON...HOWEVER GIVEN THE ISOLATED NATURE NOT MENTIONING
IN TAFS RATHER WILL AMEND AS NEEDED. JUNCTION WILL SEE SOME
MOISTURE RETURN OVERNIGHT PRODUCING MVFR CONDITIONS AGAIN.
&&
.PREV DISCUSSION... /ISSUED 606 AM CDT SAT MAY 18 2013/
DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.
AVIATION...
MID LEVEL CLOUD COVER WILL PERSIST THROUGH MID MORNING BEFORE
BEING REPLACED BY A HIGH BASED CU FIELD THAT WILL CONTINUE THROUGH
EARLY EVENING. WINDS WILL BE PREDOMINANTLY FROM THE SOUTH /170-200
DEGREES/ AND WILL INCREASE TO 15-20 KTS BY 14-15Z. I EXPECT WIND
SPEEDS TO STAY THROUGHOUT THE DAY. WINDS WILL STAY UP THIS EVENING
AT KABI/KSJT AS THE LOW LEVEL JET REDEVELOPS. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS WILL BE POSSIBLE ALONG AND EAST OF THE
DRYLINE. HOWEVER...COVERAGE SHOULD BE LIMITED SO NO THUNDER WAS
INCLUDED AT ANY PARTICULAR TAF SITE. HOWEVER...KABI AND KBBD STAND
THE BEST CHANCE OF SEEING THIS ACTIVITY /ALBEIT STILL A LOW
CHANCE/. WILL WAIT FOR THE DETAILS TO EMERGE BEFORE INCLUDING
RESTRICTIONS IN THE TAFS.
JOHNSON
PREV DISCUSSION... /ISSUED 417 AM CDT SAT MAY 18 2013/
SHORT TERM...
NEAR RECORD TEMPERATURES AND POTENTIAL SEVERE CONVECTION HIGHLIGHT
THE SHORT TERM PORTION OF THE FORECAST.
PRONOUNCED SOUTHWEST FLOW ALOFT IS EVIDENT PER 00Z UPPER AIR
ANALYSIS. SHORTWAVE RIDGING OVER THE PLAINS THAT HAS SHARED SOME
RESPONSIBILITY FOR OUR OPPRESSIVE HEAT WILL SHIFT SLOWLY EAST AS A
TROUGH MOVES ACROSS THE ROCKIES. THIS TROUGH IS TAKING ON
SOMEWHAT OF A NEGATIVE TILT BUT THE STRONGEST WINDS ALOFT REMAIN
ON ITS WESTERN FLANK. A SUBTROPICAL JET STREAK IS PROPAGATING
NORTHEAST ACROSS MEXICO THIS MORNING AND SHOULD ARRIVE THIS
EVENING. IN THE LOWER TROPOSPHERE...STRONG LEE CYCLOGENESIS HAS
ENHANCED THE NOCTURNAL LOW LEVEL JET WHICH IS CONTINUING TO PUMP
GULF MOISTURE NORTH INTO THE SOUTHERN PLAINS. DEWPOINTS ARE IN THE
60S TO LOWER 70S ACROSS THE CWA. THE DRYLINE IS CURRENTLY FOUND TO
OUR WEST AND WILL MOVE A BIT TO THE EAST TODAY. THE QUESTION
REMAINS HOW FAR EAST. MOST OF THE 00Z GUIDANCE MIXES THE DRYLINE
AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO OZONA LINE.
HOWEVER...SEVERAL OF THE HIRES CAMS HOLD THE DRYLINE FARTHER WEST
ALONG THE WESTERN BORDER OF THE CWA. GIVEN THE LACK OF A STRONG
MID LEVEL JET ROUNDING THE BASE OF THE TROUGH THROUGH EARLY
AFTERNOON /AND COLLABORATION WITH NEIGHBORING OFFICES/ I HAVE
OPTED FOR THE WESTERN PLACEMENT OF THE DRYLINE...KEEPING MOST OF
THE AREA WITHIN THE MOIST SECTOR.
THE 00Z GUIDANCE SUGGESTS TEMPS WILL BE 5-7 DEGREES COOLER THAN
YESTERDAY. HOWEVER...THE RAP WARMS SURFACE TEMPS UP TO NEAR 105
DEGREES AGAIN. WHILE THE INCREASE IN MID LEVEL CLOUDS AND
ADDITIONAL MOISTURE ON THE EAST SIDE OF THE DRYLINE WILL LIMIT
HEATING...I STILL DO NOT THINK WE WILL COOL OFF BY THAT MUCH. I
WENT WITH A COMPROMISE BETWEEN THE NAM AND RAP...WITH FORECAST
HIGHS GENERALLY 97 TO 101 DEGREES. INSTABILITY PARAMETERS ACROSS
THE AREA ARE IMPRESSIVE WITH MLCAPE VALUES OF 2000-3000 J/KG THIS
AFTERNOON. DEEP LAYER SHEAR LOOKS JUST SUFFICIENT FOR
SUPERCELLULAR ACTIVITY WITH AN ANTICIPATED 25-30 KTS OF 0-6KM
SHEAR. WITH THE INTENSE SURFACE HEATING...WE SHOULD SEE SEVERAL
UPDRAFTS PENETRATE THE CAP AND MATURE QUICKLY INTO POTENTIALLY
SEVERE THUNDERSTORMS. STEEP MID LEVEL LAPSE RATES WILL LEND TOWARD
A LARGE HAIL THREAT WITH ADIABATIC LAPSE RATES AND A DEEP...DRY
SUB CLOUD LAYER PROVIDING A WIND THREAT. THE EXTREMELY HIGH CLOUD
BASES WILL LIMIT THE TORNADO POTENTIAL THIS FAR SOUTH...BUT WILL
NOT RULE OUT THE THREAT ALTOGETHER. THE GREATEST POTENTIAL FOR
SEVERE WEATHER WILL BE ACROSS THE BIG COUNTRY WHERE THE CAP WILL
BE A BIT WEAKER BUT THE THREAT WILL EXIST AREAWIDE.
TONIGHT...ANY ONGOING CONVECTION WILL MOVE IN A GENERAL
NORTHEASTERLY DIRECTION AND MAY HANG ON FOR SEVERAL HOURS AFTER
SUNSET GIVEN THE ANTICIPATED INTERACTION OF THE LOW LEVEL
JET...DRYLINE AND INCREASING SYNOPTIC SCALE ASCENT. THE SEVERE
THREAT WILL CONTINUE AS WELL BUT WILL DECREASE ONCE WE LOSE
SURFACE HEATING. EXPECT OVERNIGHT TEMPERATURES TO FALL INTO THE
LOWER 70S FOR THE MOST PART WITH SOUTH WINDS OF 5 TO 15 MPH.
THANKS LUB FOR THE COORDINATION.
JOHNSON
LONG TERM...
NOT A LOT OF CHANGE NEXT WEEK. KEPT TEMPERATURES ABOVE GUIDANCE
ON SUNDAY...WITH SUBSIDENCE AS THE UPPER TROUGH MOVES EAST. A
LARGE...SLOW MOVING UPPER LOW IS EXPECTED TO DEVELOP OVER THE
CENTRAL AND UPPER MIDWEST EARLY NEXT WEEK. WEST CENTRAL TEXAS
WILL BE SOMEWHAT DRY SLOTTED BEING SOUTH SIDE OF THE UPPER LOW.
HOWEVER...THERE MAY STILL BE ENOUGH LOW LEVEL MOISTURE AROUND TO
GENERATE A FEW THUNDERSTORMS. THE BEST CHANCE OF STORMS IS ON
TUESDAY AS A WEAK COLD FRONT AND UPPER SHORTWAVE MOVE ACROSS THE
REGION. CAN NOT RULE OUT A FEW DRYLINE THUNDERSTORMS ON
MONDAY...AND ON THURSDAY INTO FRIDAY. WILL HOLD OFF MENTION OF
STORMS ON THESE DAYS HOWEVER ...AS RAINFALL POTENTIAL IS FAIRLY
LOW. I AM ALSO CONCERNED WITH UPPER RIDGING TAKING PLACE IN THE
SECOND HALF OF NEXT WEEK...WHICH WOULD ACT TO INHIBIT CONVECTION.
04
FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS ARE ANTICIPATED TODAY ACROSS MOST
OF WEST CENTRAL TEXAS AS TEMPERATURES WARM TO NEAR 100 DEGREES...
MINIMUM RELATIVE HUMIDITIES FALL TO 20-30 PERCENT AND SOUTH 20 FT
WINDS INCREASE TO AROUND 15-20 MPH. IN ADDITION...ISOLATED AFTERNOON
THUNDERSTORMS WILL BE POSSIBLE WHICH MAY RESULT IN OCCASIONAL CLOUD
TO GROUND LIGHTNING. RELATIVE HUMIDITIES WILL RECOVER TO 70-80
PERCENT OVERNIGHT BUT WILL TANK AGAIN ON SUNDAY AS TEMPERATURES SOAR
TO NEAR OR ABOVE 100 DEGREES YET AGAIN. ON SUNDAY AFTERNOON...THE
DRYLINE WILL MOVE A BIT FARTHER EAST...SPREADING SUB 20 PERCENT
RELATIVE HUMIDITIES AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO
OZONA LINE. SOUTHWEST 20 FT WINDS WILL BE AROUND 15 MPH...RESULTING
IN ELEVATED FIRE WEATHER CONDITIONS. EXPECT CONDITIONS TO IMPROVE
ONLY SLIGHTLY ON MONDAY BUT COOLER TEMPERATURES ARE ANTICIPATED BY
TUESDAY WHICH SHOULD ALLEVIATE FIRE WEATHER CONCERNS TEMPORARILY.
JOHNSON
CLIMATE...
THE MAX TEMP YESTERDAY IN SAN ANGELO OF 106 DEGREES SMASHED THE
PREVIOUS RECORD OF 100. LIKEWISE...ABILENE SET A NEW RECORD AS
WELL...TOPPING OUT AT 104 AND BESTING THE PREVIOUS MARK OF 101
DEGREES. WE MAY BE IN LINE FOR RECORD HIGH MINIMUM TEMPS THIS
MORNING. THE RECORDS OF 73 DEGREES AT BOTH ABILENE AND SAN ANGELO
MAY FALL AS 2 AM TEMPS ARE STILL IN THE 80S.
THIS AFTERNOON...MAX TEMPS ARE FORECAST TO WARM TO NEAR OR JUST
ABOVE 100 DEGREES. MAX TEMPS RECORDS ARE IN JEOPARDY AT BOTH
SITES. ABILENE HAS A RECORD HIGH TODAY OF 99 DEGREES WHILE SAN
ANGELO/S RECORD IS 102.
JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 100 71 97 69 94 / 20 20 5 10 10
SAN ANGELO 101 72 102 70 96 / 20 10 5 5 5
JUNCTION 97 70 99 71 91 / 10 10 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
REIMER
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1227 PM CDT SAT MAY 18 2013
.AVIATION...
THE NORTH/CENTRAL TEXAS TAF SITES WILL BE BREEZY AND
VFR THIS AFTERNOON THROUGH LATE TONIGHT. THEN...MVFR CIGS ARE
EXPECTED TO ADVECT ACROSS THE SITES...AROUND 09Z AT KACT AND BY 11Z
ACROSS THE METROPLEX. THIS IS DUE TO A STRENGTHENING LLJ TONIGHT
THAT WILL BE IN THE 40-45 KNOT RANGE LATE TONIGHT THROUGH SUNDAY MORNING.
WINDS ARE EXPECTED TO BE AROUND 18KTS WITH HIGHER GUSTS THIS
AFTERNOON...SLIGHTLY WEAKER THIS EVENING THEN INCREASING BY 06Z TO
17G27KT. WINDS ON SUNDAY SHOULD BE 20G30KTS OR JUST A BIT HIGHER
MIDDAY THROUGH LATE AFTERNOON.
A SHORTWAVE MAY DEVELOP SOME ELEVATED CONVECTION NORTH OF I-20
LATE TONIGHT. DUE TO FORECAST SOUNDING PROFILES...WE HAVE A
CONCERN ABOUT THE POTENTIAL OF HEAT BURSTS RESULTING FROM ANY
ACTIVITY THAT PASSES FAIRLY CLOSE TO THE NORTHERN MOST TAF
SITES...KAFW/KDFW/KDAL. 75
&&
.UPDATE...
12Z FWD SOUNDING SHOWS MOISTURE DEPTH HAS BEEN REDUCED AS COMPARED
TO YESTERDAY...WHICH SHOULD CAUSE DEWPOINTS TO MIX OUT INTO THE
LOW 60S WEST TO MID 60S CENTRAL AND EAST. IN ADDITION...THE LOW
LEVEL THERMAL PROFILE HAS WARMED A FEW DEGREES OVER YESTERDAY
WHICH MEANS HIGH TEMPS WILL BE A COUPLE DEGREES WARMER TODAY FOR
MOST AREAS. LIGHT ECHOES IN THE SOUTHWEST CWA THIS MORNING ARE
ASSOCIATED WITH WEAK MID LEVEL CONVECTION AND PRECIP IS LIKELY NOT
REACHING THE GROUND. PREVIOUS FORECAST WAS GENERALLY ON TRACK AND
A JUST A FEW CHANGES TO HOURLY GRIDS WERE MADE FOR TRENDS.
CONCERNING THE CONVECTIVE POTENTIAL FOR THIS AFTERNOON AND
EVENING...IT STILL APPEARS THE WESTERN AND NORTHWESTERN COUNTIES
HAVE SOME THREAT OF SEVERE STORMS BUT THERE ARE SOME MIXED
SIGNALS IN THE DATA TODAY. THE STRONG CAP WILL CONTINUE TO BE THE
PRIMARY IMPEDANCE FOR CONVECTIVE ACTIVITY. A LOWER MOISTURE DEPTH
MAY RESULT IN DEWPOINTS MIXING OUT MORE THAN FORECAST WHICH WOULD
KEEP CIN VALUES TOO HIGH. THE DRYLINE WILL ALSO BE POSITIONED
FARTHER WEST TODAY AND ALONG A LINE FROM VERNON TO SAN ANGELO.
HOWEVER...THE MODEL DATA IS IN AGREEMENT THAT A WEAK SHORTWAVE
WILL MOVE ACROSS THE NORTHWEST ZONES THIS EVENING AND RESULT IN
HEIGHT FALLS. THIS BIT OF FORCING WOULD HELP TO ERODE THE CAP AND
WOULD FAVOR CONVECTIVE INITIATION OCCURRING TO THE WEST OF THE CWA
LATE THIS AFTERNOON. MID LEVEL WESTERLY WIND FIELDS ARE SLIGHTLY
STRONGER TODAY AND STORMS WOULD HAVE THE POTENTIAL TO MOVE MORE
EASTERLY AND INTO THE WESTERN CWA BY EARLY THIS EVENING. THE RUC
KEEPS ALL ACTIVITY TO OUR WEST...BUT THE HRRR AND 12Z NAM ARE
BRINGING IT INTO THE WESTERN ZONES. SOME OF THE OTHER HI-RES
MODELS ARE NOT EVEN INITIATING...SO AGAIN POPS WILL BE GENERALLY
JUST 20 PERCENT WEST OF A GAINESVILLE TO MINERAL WELLS TO
GOLDTHWAITE DUE TO INITIATION AND STORM MOTION UNCERTAINTIES. DUE
TO STEEP LAPSE RATES...INSTABILITY WILL BE HIGH WITH CAPES LIKELY
OVER 3000 J/KG AT PEAK HEATING...AND THE MAIN SEVERE THREAT IN OUR
CWA WILL BE LARGE HAIL. ACROSS THE CENTRAL AND EASTERN ZONES THE
CAP WILL REMAIN TOO STRONG FOR SURFACE BASED CONVECTION...BUT
THESE AREAS MAY EXPERIENCE SPRINKLES AND GUSTY WINDS FROM STORM
ANVILS LATER THIS EVENING.
TR.92
&&
.SHORT TERM...
A SHORTWAVE DISTURBANCE WAS SEEN VIA WATER VAPOR SATELLITE IMAGERY
EARLY THIS MORNING ROTATING THROUGH CENTRAL/EASTERN NEW MEXICO.
THIS FEATURE WILL EJECT WITHIN INCREASING SOUTHWEST FLOW ALOFT
ACROSS WEST TX/OK BY AFTERNOON. THIS WILL DEEPEN AND MOVE THE
SURFACE DRYLINE INTO THE SOUTH PLAINS BY EARLY EVENING. LIFT FROM
BOTH OF THESE FEATURES WILL COMBINE WITH HIGH TEMPERATURES AROUND
100 DEGREES AND THE RESULTING VERY HIGH INSTABILITY FOR THE
DEVELOPMENT OF A FEW SUPERCELLS LATE IN THE DAY. THIS IS TYPICALLY
THE TIME OF THE YEAR/MID MAY-LATE JUNE/ THAT THE DRYLINE OUT WEST IS
THE MOST ACTIVE...USUALLY PRODUCING DIURNAL SEVERE WEATHER IN THE
LATE AFTERNOONS AND EARLY EVENINGS. EXPECT MORE DISCRETE SUPERCELLS
LATE TODAY AND THIS EVENING IN AND NEAR OUR FAR WESTERN COUNTIES.
CURRENT SHEAR AND BUNKERS METHOD INDICATE THERE WILL BE MORE
STEERING CURRENTS TO THE NORTHEAST VERSUS YESTERDAY WITH UPPER
TROUGH APPROACHING. HOWEVER...AS WITH ANY SUPERCELL DEVIANT
MOTIONS CANNOT BE RULED OUT ONCE ANY MESOCYCLONES DEVELOP WITHIN
THE STORMS THEMSELVES. DESPITE RELATIVELY HIGH LCLS WITH THE HOT
AND UNSTABLE AIRMASS...JUST ABOUT ALL TYPES OF SEVERE WEATHER WILL
BE POSSIBLE WITH THIS ACTIVITY. EXPECT ABOUT 20-30 PERCENT COVERAGE
OF SEVERE STORMS ACROSS THE NORTHWEST COUNTIES. THE INVERSION
STRENGTHENS ONCE AGAIN BY LATE EVENING AND EXPECT THE MAJORITY OF
ACTIVITY TO DIMINISH QUICKLY.
THE NEXT ROUND OF SEVERE WEATHER LATE SUNDAY WILL LIKELY BE MORE
ACROSS THE NORTHERN TIER COUNTIES VERSUS JUST THE WEST...AS A
NEGATIVE TILT SHORTWAVE DISTURBANCE ROTATES ACROSS THE TX/OK
PANHANDLES INTO WESTERN OK/KS. THE SURFACE DRYLINE WILL HAVE A
BETTER PUSH TO EAST ACROSS THOSE AREAS NORTH OF I-20 IN RESPONSE
TO THIS SHORTWAVE. THE HIGHER COVERAGE OF SEVERE WEATHER AND RISK
WILL BE OVER EASTERN OK INTO THE OZARKS...BUT SHOULD ZIPPER A FEW
STORMS SOUTH-SOUTHWEST ACROSS THE RED RIVER BY EVENING. ALL THREATS
WILL BE POSSIBLE ONCE AGAIN.
&&
.CLIMATE...
YESTERDAY (MAY 17) WAS THE FIRST 90-DEGREE DAY AT DFW AIRPORT THIS
YEAR. IT WAS ALSO THE FIRST TIME NORTH TEXAS HAS SEEN 100 DEGREES
IN 2013. GRAHAM HIT 101...AND BRECKENRIDGE PEAKED AT 104.
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 93 73 92 72 91 / 5 5 10 20 10
WACO, TX 92 71 91 73 90 / 5 5 10 10 10
PARIS, TX 88 70 87 68 87 / 5 5 5 20 10
DENTON, TX 93 72 90 72 90 / 5 10 10 20 10
MCKINNEY, TX 90 72 89 71 88 / 5 5 5 20 10
DALLAS, TX 93 73 91 74 91 / 5 5 10 20 10
TERRELL, TX 90 71 90 71 89 / 5 5 5 10 10
CORSICANA, TX 91 71 89 73 90 / 5 5 5 10 10
TEMPLE, TX 92 71 91 72 90 / 5 5 10 10 10
MINERAL WELLS, TX 96 70 94 69 95 / 5 20 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
75/
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1056 AM CDT SAT MAY 18 2013
.UPDATE...
12Z FWD SOUNDING SHOWS MOISTURE DEPTH HAS BEEN REDUCED AS COMPARED
TO YESTERDAY...WHICH SHOULD CAUSE DEWPOINTS TO MIX OUT INTO THE
LOW 60S WEST TO MID 60S CENTRAL AND EAST. IN ADDITION...THE LOW
LEVEL THERMAL PROFILE HAS WARMED A FEW DEGREES OVER YESTERDAY
WHICH MEANS HIGH TEMPS WILL BE A COUPLE DEGREES WARMER TODAY FOR
MOST AREAS. LIGHT ECHOES IN THE SOUTHWEST CWA THIS MORNING ARE
ASSOCIATED WITH WEAK MID LEVEL CONVECTION AND PRECIP IS LIKELY NOT
REACHING THE GROUND. PREVIOUS FORECAST WAS GENERALLY ON TRACK AND
A JUST A FEW CHANGES TO HOURLY GRIDS WERE MADE FOR TRENDS.
CONCERNING THE CONVECTIVE POTENTIAL FOR THIS AFTERNOON AND
EVENING...IT STILL APPEARS THE WESTERN AND NORTHWESTERN COUNTIES
HAVE SOME THREAT OF SEVERE STORMS BUT THERE ARE SOME MIXED
SIGNALS IN THE DATA TODAY. THE STRONG CAP WILL CONTINUE TO BE THE
PRIMARY IMPEDANCE FOR CONVECTIVE ACTIVITY. A LOWER MOISTURE DEPTH
MAY RESULT IN DEWPOINTS MIXING OUT MORE THAN FORECAST WHICH WOULD
KEEP CIN VALUES TOO HIGH. THE DRYLINE WILL ALSO BE POSITIONED
FARTHER WEST TODAY AND ALONG A LINE FROM VERNON TO SAN ANGELO.
HOWEVER...THE MODEL DATA IS IN AGREEMENT THAT A WEAK SHORTWAVE
WILL MOVE ACROSS THE NORTHWEST ZONES THIS EVENING AND RESULT IN
HEIGHT FALLS. THIS BIT OF FORCING WOULD HELP TO ERODE THE CAP AND
WOULD FAVOR CONVECTIVE INITIATION OCCURRING TO THE WEST OF THE CWA
LATE THIS AFTERNOON. MID LEVEL WESTERLY WIND FIELDS ARE SLIGHTLY
STRONGER TODAY AND STORMS WOULD HAVE THE POTENTIAL TO MOVE MORE
EASTERLY AND INTO THE WESTERN CWA BY EARLY THIS EVENING. THE RUC
KEEPS ALL ACTIVITY TO OUR WEST...BUT THE HRRR AND 12Z NAM ARE
BRINGING IT INTO THE WESTERN ZONES. SOME OF THE OTHER HI-RES
MODELS ARE NOT EVEN INITIATING...SO AGAIN POPS WILL BE GENERALLY
JUST 20 PERCENT WEST OF A GAINESVILLE TO MINERAL WELLS TO
GOLDTHWAITE DUE TO INITIATION AND STORM MOTION UNCERTAINTIES. DUE
TO STEEP LAPSE RATES...INSTABILITY WILL BE HIGH WITH CAPES LIKELY
OVER 3000 J/KG AT PEAK HEATING...AND THE MAIN SEVERE THREAT IN OUR
CWA WILL BE LARGE HAIL. ACROSS THE CENTRAL AND EASTERN ZONES THE
CAP WILL REMAIN TOO STRONG FOR SURFACE BASED CONVECTION...BUT
THESE AREAS MAY EXPERIENCE SPRINKLES AND GUSTY WINDS FROM STORM
ANVILS LATER THIS EVENING.
TR.92
&&
.AVIATION...
/12Z TAFS/
CONCERNS...NOCTURNAL STRATUS AND THUNDERSTORMS TO THE WEST.
STRATUS HAS SLOWLY MADE ITS WAY UP THE I-35 CORRIDOR OVERNIGHT. A
SIGNIFICANT WESTERLY COMPONENT ABOVE THE STRATUS IS REDUCING THE
DEPTH OF THE LAYER AND SHOULD KEEP THE DECK SOUTH AND EAST OF
METROPLEX TAF SITES.
ISOLATED THUNDERSTORMS MAY DEVELOP ACROSS WESTERN PORTIONS OF
NORTH TEXAS LATE THIS AFTERNOON. SOME OF THE ACTIVITY MAY APPROACH
THE I-35 CORRIDOR THIS EVENING. MAY IMPACT WEST DEPARTURES AND
NORTHWEST ARRIVALS...BUT DO NOT ANTICIPATE ANY ISSUES AT TAF
SITES.
A MORE VIGOROUS LLJ SUNDAY MORNING SHOULD IMPROVE THE PROBABILITY
OF MORNING STRATUS.
25
&&
.SHORT TERM...
A SHORTWAVE DISTURBANCE WAS SEEN VIA WATER VAPOR SATELLITE IMAGERY
EARLY THIS MORNING ROTATING THROUGH CENTRAL/EASTERN NEW MEXICO.
THIS FEATURE WILL EJECT WITHIN INCREASING SOUTHWEST FLOW ALOFT
ACROSS WEST TX/OK BY AFTERNOON. THIS WILL DEEPEN AND MOVE THE
SURFACE DRYLINE INTO THE SOUTH PLAINS BY EARLY EVENING. LIFT FROM
BOTH OF THESE FEATURES WILL COMBINE WITH HIGH TEMPERATURES AROUND
100 DEGREES AND THE RESULTING VERY HIGH INSTABILITY FOR THE
DEVELOPMENT OF A FEW SUPERCELLS LATE IN THE DAY. THIS IS TYPICALLY
THE TIME OF THE YEAR/MID MAY-LATE JUNE/ THAT THE DRYLINE OUT WEST IS
THE MOST ACTIVE...USUALLY PRODUCING DIURNAL SEVERE WEATHER IN THE
LATE AFTERNOONS AND EARLY EVENINGS. EXPECT MORE DISCRETE SUPERCELLS
LATE TODAY AND THIS EVENING IN AND NEAR OUR FAR WESTERN COUNTIES.
CURRENT SHEAR AND BUNKERS METHOD INDICATE THERE WILL BE MORE
STEERING CURRENTS TO THE NORTHEAST VERSUS YESTERDAY WITH UPPER
TROUGH APPROACHING. HOWEVER...AS WITH ANY SUPERCELL DEVIANT
MOTIONS CANNOT BE RULED OUT ONCE ANY MESOCYCLONES DEVELOP WITHIN
THE STORMS THEMSELVES. DESPITE RELATIVELY HIGH LCLS WITH THE HOT
AND UNSTABLE AIRMASS...JUST ABOUT ALL TYPES OF SEVERE WEATHER WILL
BE POSSIBLE WITH THIS ACTIVITY. EXPECT ABOUT 20-30 PERCENT COVERAGE
OF SEVERE STORMS ACROSS THE NORTHWEST COUNTIES. THE INVERSION
STRENGTHENS ONCE AGAIN BY LATE EVENING AND EXPECT THE MAJORITY OF
ACTIVITY TO DIMINISH QUICKLY.
THE NEXT ROUND OF SEVERE WEATHER LATE SUNDAY WILL LIKELY BE MORE
ACROSS THE NORTHERN TIER COUNTIES VERSUS JUST THE WEST...AS A
NEGATIVE TILT SHORTWAVE DISTURBANCE ROTATES ACROSS THE TX/OK
PANHANDLES INTO WESTERN OK/KS. THE SURFACE DRYLINE WILL HAVE A
BETTER PUSH TO EAST ACROSS THOSE AREAS NORTH OF I-20 IN RESPONSE
TO THIS SHORTWAVE. THE HIGHER COVERAGE OF SEVERE WEATHER AND RISK
WILL BE OVER EASTERN OK INTO THE OZARKS...BUT SHOULD ZIPPER A FEW
STORMS SOUTH-SOUTHWEST ACROSS THE RED RIVER BY EVENING. ALL THREATS
WILL BE POSSIBLE ONCE AGAIN.
&&
.CLIMATE...
YESTERDAY (MAY 17) WAS THE FIRST 90-DEGREE DAY AT DFW AIRPORT THIS
YEAR. IT WAS ALSO THE FIRST TIME NORTH TEXAS HAS SEEN 100 DEGREES
IN 2013. GRAHAM HIT 101...AND BRECKENRIDGE PEAKED AT 104.
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 93 73 92 72 91 / 5 5 10 20 10
WACO, TX 92 71 91 73 90 / 5 5 10 10 10
PARIS, TX 88 70 87 68 87 / 5 5 5 20 10
DENTON, TX 93 72 90 72 90 / 5 10 10 20 10
MCKINNEY, TX 90 72 89 71 88 / 5 5 5 20 10
DALLAS, TX 93 73 91 74 91 / 5 5 10 20 10
TERRELL, TX 90 71 90 71 89 / 5 5 5 10 10
CORSICANA, TX 91 71 89 73 90 / 5 5 5 10 10
TEMPLE, TX 92 71 91 72 90 / 5 5 10 10 10
MINERAL WELLS, TX 96 70 94 69 95 / 5 20 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
606 AM CDT SAT MAY 18 2013
.DISCUSSION...
SEE THE 12Z AVIATION DISCUSSION BELOW.
&&
.AVIATION...
MID LEVEL CLOUD COVER WILL PERSIST THROUGH MID MORNING BEFORE
BEING REPLACED BY A HIGH BASED CU FIELD THAT WILL CONTINUE THROUGH
EARLY EVENING. WINDS WILL BE PREDOMINANTLY FROM THE SOUTH /170-200
DEGREES/ AND WILL INCREASE TO 15-20 KTS BY 14-15Z. I EXPECT WIND
SPEEDS TO STAY THROUGHOUT THE DAY. WINDS WILL STAY UP THIS EVENING
AT KABI/KSJT AS THE LOW LEVEL JET REDEVELOPS. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS WILL BE POSSIBLE ALONG AND EAST OF THE
DRYLINE. HOWEVER...COVERAGE SHOULD BE LIMITED SO NO THUNDER WAS
INCLUDED AT ANY PARTICULAR TAF SITE. HOWEVER...KABI AND KBBD STAND
THE BEST CHANCE OF SEEING THIS ACTIVITY /ALBEIT STILL A LOW
CHANCE/. WILL WAIT FOR THE DETAILS TO EMERGE BEFORE INCLUDING
RESTRICTIONS IN THE TAFS.
JOHNSON
&&
.PREV DISCUSSION... /ISSUED 417 AM CDT SAT MAY 18 2013/
SHORT TERM...
NEAR RECORD TEMPERATURES AND POTENTIAL SEVERE CONVECTION HIGHLIGHT
THE SHORT TERM PORTION OF THE FORECAST.
PRONOUNCED SOUTHWEST FLOW ALOFT IS EVIDENT PER 00Z UPPER AIR
ANALYSIS. SHORTWAVE RIDGING OVER THE PLAINS THAT HAS SHARED SOME
RESPONSIBILITY FOR OUR OPPRESSIVE HEAT WILL SHIFT SLOWLY EAST AS A
TROUGH MOVES ACROSS THE ROCKIES. THIS TROUGH IS TAKING ON
SOMEWHAT OF A NEGATIVE TILT BUT THE STRONGEST WINDS ALOFT REMAIN
ON ITS WESTERN FLANK. A SUBTROPICAL JET STREAK IS PROPAGATING
NORTHEAST ACROSS MEXICO THIS MORNING AND SHOULD ARRIVE THIS
EVENING. IN THE LOWER TROPOSPHERE...STRONG LEE CYCLOGENESIS HAS
ENHANCED THE NOCTURNAL LOW LEVEL JET WHICH IS CONTINUING TO PUMP
GULF MOISTURE NORTH INTO THE SOUTHERN PLAINS. DEWPOINTS ARE IN THE
60S TO LOWER 70S ACROSS THE CWA. THE DRYLINE IS CURRENTLY FOUND TO
OUR WEST AND WILL MOVE A BIT TO THE EAST TODAY. THE QUESTION
REMAINS HOW FAR EAST. MOST OF THE 00Z GUIDANCE MIXES THE DRYLINE
AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO OZONA LINE.
HOWEVER...SEVERAL OF THE HIRES CAMS HOLD THE DRYLINE FARTHER WEST
ALONG THE WESTERN BORDER OF THE CWA. GIVEN THE LACK OF A STRONG
MID LEVEL JET ROUNDING THE BASE OF THE TROUGH THROUGH EARLY
AFTERNOON /AND COLLABORATION WITH NEIGHBORING OFFICES/ I HAVE
OPTED FOR THE WESTERN PLACEMENT OF THE DRYLINE...KEEPING MOST OF
THE AREA WITHIN THE MOIST SECTOR.
THE 00Z GUIDANCE SUGGESTS TEMPS WILL BE 5-7 DEGREES COOLER THAN
YESTERDAY. HOWEVER...THE RAP WARMS SURFACE TEMPS UP TO NEAR 105
DEGREES AGAIN. WHILE THE INCREASE IN MID LEVEL CLOUDS AND
ADDITIONAL MOISTURE ON THE EAST SIDE OF THE DRYLINE WILL LIMIT
HEATING...I STILL DO NOT THINK WE WILL COOL OFF BY THAT MUCH. I
WENT WITH A COMPROMISE BETWEEN THE NAM AND RAP...WITH FORECAST
HIGHS GENERALLY 97 TO 101 DEGREES. INSTABILITY PARAMETERS ACROSS
THE AREA ARE IMPRESSIVE WITH MLCAPE VALUES OF 2000-3000 J/KG THIS
AFTERNOON. DEEP LAYER SHEAR LOOKS JUST SUFFICIENT FOR
SUPERCELLULAR ACTIVITY WITH AN ANTICIPATED 25-30 KTS OF 0-6KM
SHEAR. WITH THE INTENSE SURFACE HEATING...WE SHOULD SEE SEVERAL
UPDRAFTS PENETRATE THE CAP AND MATURE QUICKLY INTO POTENTIALLY
SEVERE THUNDERSTORMS. STEEP MID LEVEL LAPSE RATES WILL LEND TOWARD
A LARGE HAIL THREAT WITH ADIABATIC LAPSE RATES AND A DEEP...DRY
SUB CLOUD LAYER PROVIDING A WIND THREAT. THE EXTREMELY HIGH CLOUD
BASES WILL LIMIT THE TORNADO POTENTIAL THIS FAR SOUTH...BUT WILL
NOT RULE OUT THE THREAT ALTOGETHER. THE GREATEST POTENTIAL FOR
SEVERE WEATHER WILL BE ACROSS THE BIG COUNTRY WHERE THE CAP WILL
BE A BIT WEAKER BUT THE THREAT WILL EXIST AREAWIDE.
TONIGHT...ANY ONGOING CONVECTION WILL MOVE IN A GENERAL
NORTHEASTERLY DIRECTION AND MAY HANG ON FOR SEVERAL HOURS AFTER
SUNSET GIVEN THE ANTICIPATED INTERACTION OF THE LOW LEVEL
JET...DRYLINE AND INCREASING SYNOPTIC SCALE ASCENT. THE SEVERE
THREAT WILL CONTINUE AS WELL BUT WILL DECREASE ONCE WE LOSE
SURFACE HEATING. EXPECT OVERNIGHT TEMPERATURES TO FALL INTO THE
LOWER 70S FOR THE MOST PART WITH SOUTH WINDS OF 5 TO 15 MPH.
THANKS LUB FOR THE COORDINATION.
JOHNSON
LONG TERM...
NOT A LOT OF CHANGE NEXT WEEK. KEPT TEMPERATURES ABOVE GUIDANCE
ON SUNDAY...WITH SUBSIDENCE AS THE UPPER TROUGH MOVES EAST. A
LARGE...SLOW MOVING UPPER LOW IS EXPECTED TO DEVELOP OVER THE
CENTRAL AND UPPER MIDWEST EARLY NEXT WEEK. WEST CENTRAL TEXAS
WILL BE SOMEWHAT DRY SLOTTED BEING SOUTH SIDE OF THE UPPER LOW.
HOWEVER...THERE MAY STILL BE ENOUGH LOW LEVEL MOISTURE AROUND TO
GENERATE A FEW THUNDERSTORMS. THE BEST CHANCE OF STORMS IS ON
TUESDAY AS A WEAK COLD FRONT AND UPPER SHORTWAVE MOVE ACROSS THE
REGION. CAN NOT RULE OUT A FEW DRYLINE THUNDERSTORMS ON
MONDAY...AND ON THURSDAY INTO FRIDAY. WILL HOLD OFF MENTION OF
STORMS ON THESE DAYS HOWEVER ...AS RAINFALL POTENTIAL IS FAIRLY
LOW. I AM ALSO CONCERNED WITH UPPER RIDGING TAKING PLACE IN THE
SECOND HALF OF NEXT WEEK...WHICH WOULD ACT TO INHIBIT CONVECTION.
04
FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS ARE ANTICIPATED TODAY ACROSS MOST
OF WEST CENTRAL TEXAS AS TEMPERATURES WARM TO NEAR 100 DEGREES...
MINIMUM RELATIVE HUMIDITIES FALL TO 20-30 PERCENT AND SOUTH 20 FT
WINDS INCREASE TO AROUND 15-20 MPH. IN ADDITION...ISOLATED AFTERNOON
THUNDERSTORMS WILL BE POSSIBLE WHICH MAY RESULT IN OCCASIONAL CLOUD
TO GROUND LIGHTNING. RELATIVE HUMIDITIES WILL RECOVER TO 70-80
PERCENT OVERNIGHT BUT WILL TANK AGAIN ON SUNDAY AS TEMPERATURES SOAR
TO NEAR OR ABOVE 100 DEGREES YET AGAIN. ON SUNDAY AFTERNOON...THE
DRYLINE WILL MOVE A BIT FARTHER EAST...SPREADING SUB 20 PERCENT
RELATIVE HUMIDITIES AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO
OZONA LINE. SOUTHWEST 20 FT WINDS WILL BE AROUND 15 MPH...RESULTING
IN ELEVATED FIRE WEATHER CONDITIONS. EXPECT CONDITIONS TO IMPROVE
ONLY SLIGHTLY ON MONDAY BUT COOLER TEMPERATURES ARE ANTICIPATED BY
TUESDAY WHICH SHOULD ALLEVIATE FIRE WEATHER CONCERNS TEMPORARILY.
JOHNSON
CLIMATE...
THE MAX TEMP YESTERDAY IN SAN ANGELO OF 106 DEGREES SMASHED THE
PREVIOUS RECORD OF 100. LIKEWISE...ABILENE SET A NEW RECORD AS
WELL...TOPPING OUT AT 104 AND BESTING THE PREVIOUS MARK OF 101
DEGREES. WE MAY BE IN LINE FOR RECORD HIGH MINIMUM TEMPS THIS
MORNING. THE RECORDS OF 73 DEGREES AT BOTH ABILENE AND SAN ANGELO
MAY FALL AS 2 AM TEMPS ARE STILL IN THE 80S.
THIS AFTERNOON...MAX TEMPS ARE FORECAST TO WARM TO NEAR OR JUST
ABOVE 100 DEGREES. MAX TEMPS RECORDS ARE IN JEOPARDY AT BOTH
SITES. ABILENE HAS A RECORD HIGH TODAY OF 99 DEGREES WHILE SAN
ANGELO/S RECORD IS 102.
JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 100 71 97 69 94 / 20 20 5 10 10
SAN ANGELO 101 72 102 70 96 / 20 10 5 5 5
JUNCTION 97 70 99 71 91 / 10 10 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
417 AM CDT SAT MAY 18 2013
.SHORT TERM...
NEAR RECORD TEMPERATURES AND POTENTIAL SEVERE CONVECTION HIGHLIGHT
THE SHORT TERM PORTION OF THE FORECAST.
PRONOUNCED SOUTHWEST FLOW ALOFT IS EVIDENT PER 00Z UPPER AIR
ANALYSIS. SHORTWAVE RIDGING OVER THE PLAINS THAT HAS SHARED SOME
RESPONSIBILITY FOR OUR OPPRESSIVE HEAT WILL SHIFT SLOWLY EAST AS A
TROUGH MOVES ACROSS THE ROCKIES. THIS TROUGH IS TAKING ON SOMEWHAT
OF A NEGATIVE TILT BUT THE STRONGEST WINDS ALOFT REMAIN ON ITS
WESTERN FLANK. A SUBTROPICAL JET STREAK IS PROPAGATING NORTHEAST
ACROSS MEXICO THIS MORNING AND SHOULD ARRIVE THIS EVENING. IN THE
LOWER TROPOSPHERE...STRONG LEE CYCLOGENESIS HAS ENHANCED THE
NOCTURNAL LOW LEVEL JET WHICH IS CONTINUING TO PUMP GULF MOISTURE
NORTH INTO THE SOUTHERN PLAINS. DEWPOINTS ARE IN THE 60S TO LOWER
70S ACROSS THE CWA. THE DRYLINE IS CURRENTLY FOUND TO OUR WEST AND
WILL MOVE A BIT TO THE EAST TODAY. THE QUESTION REMAINS HOW FAR
EAST. MOST OF THE 00Z GUIDANCE MIXES THE DRYLINE AS FAR EAST AS A
HASKELL...TO SAN ANGELO...TO OZONA LINE. HOWEVER...SEVERAL OF THE
HIRES CAMS HOLD THE DRYLINE FARTHER WEST ALONG THE WESTERN BORDER OF
THE CWA. GIVEN THE LACK OF A STRONG MID LEVEL JET ROUNDING THE BASE
OF THE TROUGH THROUGH EARLY AFTERNOON /AND COLLABORATION WITH
NEIGHBORING OFFICES/ I HAVE OPTED FOR THE WESTERN PLACEMENT OF THE
DRYLINE...KEEPING MOST OF THE AREA WITHIN THE MOIST SECTOR.
THE 00Z GUIDANCE SUGGESTS TEMPS WILL BE 5-7 DEGREES COOLER THAN
YESTERDAY. HOWEVER...THE RAP WARMS SURFACE TEMPS UP TO NEAR 105
DEGREES AGAIN. WHILE THE INCREASE IN MID LEVEL CLOUDS AND ADDITIONAL
MOISTURE ON THE EAST SIDE OF THE DRYLINE WILL LIMIT HEATING...I
STILL DO NOT THINK WE WILL COOL OFF BY THAT MUCH. I WENT WITH A
COMPROMISE BETWEEN THE NAM AND RAP...WITH FORECAST HIGHS GENERALLY
97 TO 101 DEGREES. INSTABILITY PARAMETERS ACROSS THE AREA ARE
IMPRESSIVE WITH MLCAPE VALUES OF 2000-3000 J/KG THIS AFTERNOON. DEEP
LAYER SHEAR LOOKS JUST SUFFICIENT FOR SUPERCELLULAR ACTIVITY WITH AN
ANTICIPATED 25-30 KTS OF 0-6KM SHEAR. WITH THE INTENSE SURFACE
HEATING...WE SHOULD SEE SEVERAL UPDRAFTS PENETRATE THE CAP AND
MATURE QUICKLY INTO POTENTIALLY SEVERE THUNDERSTORMS. STEEP MID
LEVEL LAPSE RATES WILL LEND TOWARD A LARGE HAIL THREAT WITH
ADIABATIC LAPSE RATES AND A DEEP...DRY SUB CLOUD LAYER PROVIDING A
WIND THREAT. THE EXTREMELY HIGH CLOUD BASES WILL LIMIT THE TORNADO
POTENTIAL THIS FAR SOUTH...BUT WILL NOT RULE OUT THE THREAT
ALTOGETHER. THE GREATEST POTENTIAL FOR SEVERE WEATHER WILL BE ACROSS
THE BIG COUNTRY WHERE THE CAP WILL BE A BIT WEAKER BUT THE THREAT
WILL EXIST AREAWIDE.
TONIGHT...ANY ONGOING CONVECTION WILL MOVE IN A GENERAL
NORTHEASTERLY DIRECTION AND MAY HANG ON FOR SEVERAL HOURS AFTER
SUNSET GIVEN THE ANTICIPATED INTERACTION OF THE LOW LEVEL
JET...DRYLINE AND INCREASING SYNOPTIC SCALE ASCENT. THE SEVERE
THREAT WILL CONTINUE AS WELL BUT WILL DECREASE ONCE WE LOSE SURFACE
HEATING. EXPECT OVERNIGHT TEMPERATURES TO FALL INTO THE LOWER 70S
FOR THE MOST PART WITH SOUTH WINDS OF 5 TO 15 MPH.
THANKS LUB FOR THE COORDINATION.
JOHNSON
.LONG TERM...
NOT A LOT OF CHANGE NEXT WEEK. KEPT TEMPERATURES ABOVE GUIDANCE
ON SUNDAY...WITH SUBSIDENCE AS THE UPPER TROUGH MOVES EAST. A
LARGE...SLOW MOVING UPPER LOW IS EXPECTED TO DEVELOP OVER THE
CENTRAL AND UPPER MIDWEST EARLY NEXT WEEK. WEST CENTRAL TEXAS
WILL BE SOMEWHAT DRYSLOTTED BEING SOUTH SIDE OF THE UPPER LOW.
HOWEVER...THERE MAY STILL BE ENOUGH LOW LEVEL MOISTURE AROUND TO
GENERATE A FEW THUNDERSTORMS. THE BEST CHANCE OF STORMS IS ON
TUESDAY AS A WEAK COLD FRONT AND UPPER SHORTWAVE MOVE ACROSS THE
REGION. CAN NOT RULE OUT A FEW DRYLINE THUNDERSTORMS ON
MONDAY...AND ON THURSDAY INTO FRIDAY. WILL HOLD OFF MENTION OF
STORMS ON THESE DAYS HOWEVER ...AS RAINFALL POTENTIAL IS FAIRLY
LOW. I AM ALSO CONCERNED WITH UPPER RIDGING TAKING PLACE IN THE
SECOND HALF OF NEXT WEEK...WHICH WOULD ACT TO INHIBIT CONVECTION.
04
&&
.FIRE WEATHER...
ELEVATED FIRE WEATHER CONDITIONS ARE ANTICIPATED TODAY ACROSS MOST
OF WEST CENTRAL TEXAS AS TEMPERATURES WARM TO NEAR 100 DEGREES...
MINIMUM RELATIVE HUMIDITIES FALL TO 20-30 PERCENT AND SOUTH 20 FT
WINDS INCREASE TO AROUND 15-20 MPH. IN ADDITION...ISOLATED AFTERNOON
THUNDERSTORMS WILL BE POSSIBLE WHICH MAY RESULT IN OCCASIONAL CLOUD
TO GROUND LIGHTNING. RELATIVE HUMIDITIES WILL RECOVER TO 70-80
PERCENT OVERNIGHT BUT WILL TANK AGAIN ON SUNDAY AS TEMPERATURES SOAR
TO NEAR OR ABOVE 100 DEGREES YET AGAIN. ON SUNDAY AFTERNOON...THE
DRYLINE WILL MOVE A BIT FARTHER EAST...SPREADING SUB 20 PERCENT
RELATIVE HUMIDITIES AS FAR EAST AS A HASKELL...TO SAN ANGELO...TO
OZONA LINE. SOUTHWEST 20 FT WINDS WILL BE AROUND 15 MPH...RESULTING
IN ELEVATED FIRE WEATHER CONDITIONS. EXPECT CONDITIONS TO IMPROVE
ONLY SLIGHTLY ON MONDAY BUT COOLER TEMPERATURES ARE ANTICIPATED BY
TUESDAY WHICH SHOULD ALLEVIATE FIRE WEATHER CONCERNS TEMPORARILY.
JOHNSON
&&
.CLIMATE...
THE MAX TEMP YESTERDAY IN SAN ANGELO OF 106 DEGREES SMASHED THE
PREVIOUS RECORD OF 100. LIKEWISE...ABILENE SET A NEW RECORD AS
WELL...TOPPING OUT AT 104 AND BESTING THE PREVIOUS MARK OF 101
DEGREES. WE MAY BE IN LINE FOR RECORD HIGH MINIMUM TEMPS THIS
MORNING. THE RECORDS OF 73 DEGREES AT BOTH ABILENE AND SAN ANGELO
MAY FALL AS 2 AM TEMPS ARE STILL IN THE 80S.
THIS AFTERNOON...MAX TEMPS ARE FORECAST TO WARM TO NEAR OR JUST
ABOVE 100 DEGREES. MAX TEMPS RECORDS ARE IN JEOPARDY AT BOTH SITES.
ABILENE HAS A RECORD HIGH TODAY OF 99 DEGREES WHILE SAN ANGELO/S
RECORD IS 102.
JOHNSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 100 71 97 69 94 / 20 20 5 10 10
SAN ANGELO 101 72 102 70 96 / 20 10 5 5 5
JUNCTION 97 70 99 71 91 / 10 10 10 10 5
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/04
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1148 PM CDT FRI MAY 17 2013
.UPDATE...
SENT OUT A QUICK FORECAST UPDATE TO BUMP UP POPS A BIT FOR AREAS
ALONG AND WEST OF A LINE FROM BOWIE TO LAMPASAS. THE PRIMARY
REASON FOR THIS IS THAT AFTERNOON HIGH RESOLUTION MODEL GUIDANCE
IS MORE AGGRESSIVE WITH ISOLATED THUNDERSTORM INITIATION EAST OF
THE DRYLINE NEAR OUR FAR WESTERN CWA LATE TOMORROW AFTERNOON. THIS
ISOLATED CONVECTION IS INITIATED IN A MODELED ENVIRONMENT
CHARACTERIZED BY 3000 TO 3500 J/KG OF CAPE AND WEAK TO MODERATE
VALUES OF DEEP LAYER BULK SHEAR. THE COMBINATION OF POTENTIAL
ENERGY FOR CONVECTION AND DEEP LAYER SHEAR SHOULD SUPPORT
SUPERCELL THUNDERSTORMS ASSUMING CONVECTION INITIATES AS HIGH
RESOLUTION MODELS ADVERTISE. THERE WILL BE A CAP IN PLACE OVER
MUCH OF NORTH TEXAS...SO ONCE AGAIN THINK THUNDERSTORMS WILL
STRUGGLE TO MOVE EAST OF THIS LINE FROM BOWIE TO LAMPASAS TOMORROW
AFTERNOON OR EVENING. LARGE HAIL AND DAMAGING WINDS WOULD BE THE
PRIMARY HAZARDS...HOWEVER A TORNADO THREAT CANNOT BE RULED OUT.
BACK TO THE CAP...THE 00Z FWD SOUNDING THIS EVENING SHOWED A STOUT
CAP WITH A DEEP DRY ADIABATIC LAYER EXTENDING ABOVE THE CAP FROM
850 MB UP PAST 600 MB. THIS LAYER HAS LAPSE RATES AS STEEP AS OUR
ATMOSPHERE WILL ALLOW AWAY FROM GROUND LEVEL. ANY PRECIPITATION
INTO THIS LAYER OF STEEP LAPSE RATES AND LOW RELATIVE HUMIDITY
WILL ACCELERATE AIR DOWNWARD QUICKLY AS THIS REPRESENTS THE IDEAL
ENVIRONMENT FOR RAIN DROPS TO EVAPORATE...ADDING NEGATIVE
BUOYANCY TO AIR THAT IS ALREADY HEADED TOWARDS THE EARTH. THIS
WILL LIKELY SUPPORT HEAT BURSTS THROUGHOUT THE OVERNIGHT HOURS
WHICH IS WHAT WAS HAPPENED IN COMANCHE EARLIER THIS EVENING. A
LIGHT TO MODERATE ELEVATED RAIN SHOWER MOVED OVER COMANCHE AND
CAUSE THE TEMPERATURE TO CLIMB 4 DEGREES WHILE THE DEW POINT
DROPPED 24 DEGREES AND WINDS GUSTED TO 57 MPH. GRANTED...WE DO NOT
EXPECT MUCH IN THE WAY OF RAIN SHOWER ACTIVITY ACROSS NORTH TX
TONIGHT...BUT THERE IS A WEAK SHORTWAVE TROUGH UPSTREAM...AND IT
WOULD NOT TAKE MUCH OF A RAIN SHOWER TO INITIATE A HEAT BURST. THIS
IS SOMETHING WE WILL BE KEEPING A CLOSE EYE ON THROUGHOUT THE
OVERNIGHT HOURS. NO OTHER SIGNIFICANT CHANGES WERE MADE TO THE
FORECAST.
CAVANAUGH
&&
.AVIATION...
AN UPDATE FROM THE 00Z TAFS...LIGHT RAIN...MOSTLY EVAPORATING
BEFORE REACHING THE GROUND. THIS LIGHT RAIN WAS CAUSING WINDS TO
GUST UP TO 35 TO 40 MPH TO THE NORTHWEST OF THE METROPLEX...AND
WAS PRODUCING ISOLATED CLOUD TO GROUND LIGHTNING STRIKES OVER THE
SAME AREAS. AT THIS TIME IT LOOKS LIKE THE CORE OF THIS LIGHT
ANVIL CLOUD PRECIP WILL REMAIN NORTHWEST OF DFW AIRPORT...BUT WILL
BE WATCHING LOCAL AREA OBS CLOSELY FOR ANY DEVIATION FROM THIS
THINKING. WENT AHEAD AND AMENDED KAFW FOR VCTS AND GUSTY WINDS
FROM 02 TO 03Z DUE TO A RECORDED LIGHTNING STRIKE AROUND HASLET.
THE STORMS OUT WEST ARE BEGINNING TO DISSIPATE...SO THE THREAT FOR
GUSTY WINDS AND ANVIL CLOUD LIGHTNING STRIKES IS EXPECTED TO
DIMINISH THROUGH 04Z AS WELL.
CAVANAUGH
.../PREVIOUS AVIATION DISCUSSION/...
FOR THE 00Z TAFS...TIMING THE ONSET OF MVFR CIGS AND WATCHING FOR
ANY IMPACT TO TAF SITES FROM STORMS OUT WEST ARE THE PRIMARY
FORECAST CONCERNS.
AT THIS TIME...THE CAP ALOFT OVER AREA TAF SITES LOOKS TOO STRONG
TO ALLOW STORMS ONGOING NEAR SAN SABA AND GRAHAM TO MOVE EAST AND
DIRECTLY IMPACT THE INTERSTATE 35 CORRIDOR. STORMS WOULD LIKELY
DISSIPATE BEFORE MINERAL WELLS IF THEY STARTED TO MOVE EAST THIS
EVENING. WILL CONTINUE TO MONITOR THE IMPACT OF THESE STORMS ON
AREA TAF SITES HOWEVER AS ANVIL CLOUDS ARE THICK AND HAVE PRODUCED
LIGHTNING STRIKES AS FAR EAST AS DECATUR THIS EVENING. IF
LIGHTNING LOOKS TO IMPACT LOCAL AREA TAFS THIS EVENING MAY HAVE TO
ISSUE AN AIRPORT WEATHER WARNING FOR DFW AND AMEND TAFS TO MENTION
A THUNDERSTORM WITH NO RAIN. AT THIS TIME...THE PRESENCE OF SOME
HIGHER MID-LEVEL RH PRECLUDES A LARGER THREAT FOR HEAT BURSTS
ASSOCIATED WITH ANVIL CLOUD LIGHT PRECIPITATION.
DID NOT CHANGE THE TIMING OF THE ONSET OF MVFR STRATUS OVER AREA
TAF SITES AT THIS TIME. THE LAMP GUIDANCE IS THE MOST AGGRESSIVE
WITH THIS WITH LESS SUPPORT FROM RAP AND NAM FORECAST SOUNDINGS.
WILL MONITOR UPSTREAM STRATUS DEVELOPMENT TONIGHT AND MAY PULL
STRATUS FROM THE FORECAST BY 06Z IF THERE IS LITTLE UPSTREAM
DEVELOPMENT.
CAVANAUGH
&&
.SHORT TERM...
DRYLINE IS SHARPENING AND IS LOCATED FROM OLNEY TO BRECKENRIDGE
TO BRADY. THE DRYLINE HAS LIKELY REACHED ITS EASTERN MOST
LOCATION...AS A SURFACE LOW INDUCED BY VERY HOT TEMPERATURES IS
DEEPENING NORTH OF ABILENE. THIS HAS CAUSED SURFACE WINDS TO BEGIN
TO BACK TO THE SOUTHEAST ACROSS THE NW CWA...WHICH WILL PULL RICH
LOW LEVEL MOISTURE CHARACTERIZED BY DEWPOINTS NEAR 70 DEGREES BACK
TO THE WEST. THE COMBINATION OF TEMPS NEAR 100 WITH THESE DEWPOINTS
AND NEARLY DRY ADIABATIC LAPSE RATES FROM 500MB TO 850MB HAS
PRODUCED AN EXTREMELY UNSTABLE AIRMASS ACROSS OUR WESTERN ZONES
THIS AFTERNOON. LOCAL OBJECTIVE ANALYSIS IS DEPICTING SBCAPE
AROUND 3500 J/KG...AND POCKETS OF CAPE OVER 4000 J/KG WILL BE
POSSIBLE THROUGH EARLY EVENING. THE STRONG CAP THAT WAS EVIDENT ON
THE MORNING SOUNDING IS CLOSE TO BEING ERODED OVER THE WESTERN
ZONES...OR THE WESTERN 2 COLUMNS OF COUNTIES OF THE CWA. ALONG AND
EAST OF A BOWIE TO GRANBURY TO TEMPLE LINE...OBJECTIVE ANALYSIS
SHOWS CIN WELL ABOVE 200 J/KG AND VIS SATELLITE CONFIRMS THE
PRESENCE OF STRONG CAPPING IN CUMULUS FIELD. WITHOUT UPPER LEVEL
FORCING THIS CAP SHOULD REMAIN...WITH HEATING NOT SUFFICIENT ALONE
TO WEAKEN IT.
CONVECTIVE INITIATION IS NOW OCCURRING SOUTHWEST OF BROWNWOOD AND
CUMULUS IS ORGANIZING TO THE WEST OF BRECKENRIDGE. THIS IS TO
THE WEST OF THE DRY LINE...BUT THIS IS ACTUALLY THE FAVORED
LOCATION FOR UPWARD MESOSCALE FORCING ASSOCIATED WITH DRYLINES.
OFTEN THE LOW MOISTURE CONTENT BEHIND THE DRY LINE IS NOT
SUFFICIENT TO PRODUCE CUMULUS OR PRECIPITATION SO WE CANT SEE THE
LIFT...BUT THIS DRY LINE SEEMS TO HAVE MORE MOISTURE TO WORK WITH.
ONCE THE INFANT UPDRAFTS ARE ADVECTED TO THE MOIST SIDE OF THE DRY
LINE...THEY TAP INTO RICHER MOISTURE AND OFTEN GROW INTO CELLS
THAT RADAR CAN SEE. NEEDLESS TO SAY...CONVECTIVE INITIATION IS A
CERTAINTY AT THIS POINT...BUT COVERAGE OF STORMS WILL BE FAIRLY
LOW DUE TO WEAK UPPER LEVEL FORCING AND THE STRONG CAP. POPS WILL
RANGE FROM 20-40 PERCENT ACROSS THE WESTERN THIRD OF THE CWA.
DEEP LAYER SHEAR IS ON THE LOW SIDE OF WHAT IS TYPICALLY FOUND IN
SUPERCELL ENVIRONMENTS...BUT EXTREME INSTABILITY WILL LIKELY
COMPENSATE. STORM MOTION WILL START OUT EAST BUT AS SUPERCELLS
ORGANIZE AND MATURE THEY WILL LIKELY TURN TO THE SOUTH. THIS
SOUTHWARD MOVEMENT WILL ENHANCE LOW LEVEL STORM RELATIVE
HELICITY...WHICH MAY REACH 150-200 MS/S2 ACROSS THE NW ZONES WHERE
AN ISOLATED TORNADO THREAT IS GREATEST. HOWEVER THE MAIN THREAT
WILL BE GIANT HAIL AND DAMAGING WINDS GIVEN THE EXTREME INSTABILITY
AND LARGE DEWPOINT SPREADS. SPC HAS JUST ISSUED A SEVERE WATCH FOR
THE WESTERN ZONES...AND AGAIN DUE TO THE STRONG CAP AND SOUTHERLY
STORM MOTION BELIEVE ALL SEVERE ACTIVITY WILL REMAIN WEST OF THE
I-35 CORRIDOR. SOME LINGERING AND ELEVATED ACTIVITY MAY IMPACT THE
CENTRAL ZONES LATE TONIGHT...BUT THIS REMAINS A LOW PROBABILITY
AND KEPT POPS OUT OF THE FORECAST.
TR.92
&&
.LONG TERM...
A STRONG CAP WILL REMAIN IN PLACE ACROSS NORTH TEXAS THROUGH
MONDAY...SO THE CONVECTIVE FORECAST WILL HINGE ON WHETHER FORCING
FROM THE DRY LINE OR UPPER LEVEL SHORTWAVES WILL BE PRESENT. THE
DRYLINE WILL HEAD FARTHER WEST SATURDAY...AND ALTHOUGH A WELL
DEFINED SHORTWAVE MOVES ACROSS THE REGION...BELIEVE STORM
INITIATION WILL BE WELL NW OF THE CWA. A FEW OF THESE CELLS MAY
TRACK INTO THE NORTHWESTERN PARTS OF THE CWA SATURDAY
EVENING...BUT WILL KEEP POPS LOW AND AT 20 PERCENT. ON SUNDAY THE
DRY LINE WILL MIX EAST AGAIN AND FLIRT WITH THE NW CWA...AND HAVE
POPS A LITTLE HIGHER...BUT STILL PRIMARILY OVER THE NW ZONES IN
THE AFTERNOON. SINCE THE TAIL END OF THE PLAINS TROUGH WILL PASS
THROUGH THE NORTHERN ZONES SUNDAY NIGHT...CONVECTION MAY SURVIVE
PAST SUNSET AND TRACK ACROSS THE AREA NORTH OF I-20. EXPECT THE
SAME PATTERN ON MONDAY AND POPS ARE SIMILAR TO SUNDAYS. GIVEN THE
INSTABILITY AND SHEAR PROFILES SEVERE STORMS ARE POSSIBLE WITH ANY
ACTIVITY SATURDAY THROUGH MONDAY. FOR TEMPERATURES...SATURDAY WILL
BE THE WARMEST DAY WITH HIGHS IN THE 90S MOST AREAS...BUT WINDS
WILL INCREASE A BIT SUNDAY AND MONDAY WHICH SHOULD SHAVE A COUPLE
DEGREES...WITH HIGHS IN THE UPPER 80S EAST TO MID 90S WEST. LOWS
WILL REMAIN MUGGY AND IN THE LOW-MID 70S...WITH TONIGHT THE
COOLEST DUE TO FEWER CLOUDS AND LIGHTER WINDS.
ON TUESDAY ANOTHER LOBE OF ENERGY WILL ROTATE AROUND THE PLAINS
TROUGH AND HELP PROPEL A WEAK COLD FRONT SOUTH INTO THE AREA. THE
FRONT/DRYLINE COMBINATION WILL REACH THE NW CWA AND BECOME A FOCUS
FOR CONVECTION BY TUESDAY AFTERNOON. STRONG FORCING ASSOCIATED
WITH THE UPPER SHORTWAVE TROUGH WILL ENHANCE LIFT...AND EXPECT
SCATTERED CONVECTION TO OCCUR TUESDAY AFTERNOON AND WORK
SOUTHEAST ACROSS THE AREA. HAVE BUMPED POPS UP TO CHANCE AS THIS
WILL BE THE BEST DAY FOR RAIN CHANCES. AGAIN...THERE IS A SEVERE
WEATHER THREAT WITH THIS CONVECTION AS WELL.
THE FRONT WILL NOT BE VERY STRONG...AND WINDS MAY NOT SPEND MUCH
OR ANY TIME FROM THE NORTH...BUT THE AXIS OF BEST MOISTURE AND
INSTABILITY SHOULD GET PUSHED SOUTHEAST OF THE AREA. WILL KEEP A
SLIGHT CHANCE OF CONVECTION WEDNESDAY...BUT THIS ACTIVITY IS NOT
EXPECTED TO BE VERY SIGNIFICANT. TEMPS WILL BE A LITTLE COOLER AS
HEIGHTS LOWER...AND THE SLIGHTLY DRIER AIR WILL HELP LOWS FALL TO
NEAR NORMAL. HAVE KEPT THE REMAINDER OF THE FORECAST DRY AS UPPER
LEVEL RIDGING BUILDS INTO THE AREA...WHICH IS WELL AGREED UPON BY
EXTENDED GUIDANCE.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 92 72 90 72 / 10 5 5 10 20
WACO, TX 70 92 72 91 73 / 10 5 5 10 10
PARIS, TX 69 88 70 87 68 / 10 10 5 5 20
DENTON, TX 70 93 72 90 72 / 10 10 10 10 30
MCKINNEY, TX 69 90 71 89 71 / 10 5 5 5 20
DALLAS, TX 73 93 74 91 74 / 10 5 5 10 20
TERRELL, TX 69 90 70 91 71 / 10 5 5 5 10
CORSICANA, TX 70 90 70 89 73 / 10 5 5 5 10
TEMPLE, TX 69 92 71 91 72 / 20 10 5 10 10
MINERAL WELLS, TX 71 96 69 94 70 / 20 10 20 20 20
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
800 PM CDT SUN MAY 19 2013
.MESOSCALE DISCUSSION...
ISSUED AT 800 PM CDT SUN MAY 19 2013
WITH AMPLE MUCAPE /2000 J-KG/ IN NORTHEAST IOWA AND THE STORMS
HEADING INTO THAT AREA FROM CENTRAL IOWA...CURRENT THINKING IS THE
STORMS WILL COLD POOL TOGETHER AND FORM A SQUALL LINE THAT WILL
MOVE ACROSS NORTHEAST IOWA AND INTO WISCONSIN. DEEP SHEAR IS
PRETTY GOOD...OVER 40 KTS FOR SUPERCELLS....BUT ISOLATED
CONVECTION WILL ONLY BE FOUND AHEAD OF THE LINE. OTHERWISE...THE
0-3KM SHEAR IS AROUND 20 KTS WHICH IS NOT THAT STRONG. SO...A
MODERATELY STRONG SQUALL LINE WITH BROKEN SEVERE SEGMENTS MOVING
ACROSS THE FORECAST AREA THROUGH ABOUT 12-1 AM IS THE LATEST PLAN.
THIS LINE SHOULD DISRUPT THE BOUNDARY PINNED OVER MITCHELL COUNTY
AND END THE RAINFALL EVENT THIS EVENING...PROBABLY BY 10 PM.
&&
.SHORT TERM...(TONIGHT AND MONDAY)
ISSUED AT 220 PM CDT SUN MAY 19 2013
UPPER LEVEL SHORTWAVE TROUGH SERVING AS ONE FOCUS FOR STORM
DEVELOPMENT EARLY THIS AFTERNOON. SKIES HAVE CLEARED AHEAD OF THE
SHORTWAVE...MOVING NORTH/NORTHEAST ACROSS IOWA...ALLOWING FOR RAPID
DESTABILIZATION OF THE ATMOSPHERE. MUCAPES PER LATEST RAP ANALYSIS
HAVE RISEN INTO THE 2-3 K J/KG RANGE...WITH 30-40 KTS OF EFFECTIVE
SHEAR. SUPERCELL DEVELOPMENT IS SUPPORTED. SEE A POTENTIAL FOR ALL
SEVERE WEATHER TYPES...WITH SUPERCELLS MORPHING INTO BOWING
SEGMENTS. THINK DAMAGING WINDS MIGHT BECOME THE GREATER THREAT LATER
THIS AFTERNOON AND EVENING.
HRRR SUGGESTS THERE WILL BE ANOTHER ROUND OF STRONG/SEVERE STORMS
COMING IN TOWARD 06S AS A SHORTWAVE PUSHES NORTHWARD ACROSS IOWA.
INSTABILITY WOULD DECREASE WITH THE LOSS OF DAYTIME HEATING...BUT
GFS/NAM STILL SUGGEST 1000+ J/KG OF MUCAPE AT 06Z...WITH 40+ KTS OF
0-6 KM SHEAR. PLENTY TO CONTINUE A SEVERE THREAT.
FOR MONDAY...ATMOSPHERE PROGGED TO RELOAD FOR THE AFTERNOON/EVENING
WITH MUCAPES UPWARDS OF 2500 J/KG AND MLCAPES UP TO 2000 J/KG. 0-6KM
WIND SHEAR CLIMBS TO 40-50 KTS BY 00Z TUE...SUPPORTIVE OF SUPERCELL
DEVELOPMENT. 0-1KM SHEAR IS 15-20 KTS. IF ALL THIS COMES TO
PASS...ATMOSPHERE WOULD BE RIPE FOR SEVERE WEATHER...WITH ROTATING
SUPERCELLS AND THE GAMBIT OF SEVERE THREATS. THE KEY IS THE
KICKER...AND THAT IS WHERE THE FORECAST CHALLENGE LIES. GFS/NAM
SUGGEST A SHORTWAVE TROUGH COULD LIFT OUT OF THE BASE OF THE UPPER
LEVEL TROUGH FOR THE AFTERNOON/EVENING...BUT ALSO POINT TO POSSIBLE
MCVS SPINNING INTO THE REGION. MEANWHILE...THERE WILL LIKELY BE LEFT
OVER SFC BOUNDARIES FROM CONVECTION TODAY/TONIGHT. WHERE THESE LIE
IS UNKNOWN. CONFIDENCE IS NOT HIGH IN WHERE/WHEN CONVECTION WILL
FIRE...BUT BELIEVE THE LATE AFTERNOON/EVENING WOULD BE THE FAVORED
TIME FOR A SEVERE THREAT...AND GENERALLY FROM CENTRAL WI INTO
NORTHEAST IA.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 220 PM CDT SUN MAY 19 2013
THE VIRTUALLY STATIONARY UPPER LEVEL LOW FINALLY STARTS TO MAKE ITS
WAY EAST OUT OF THE NORTHERN PLAINS TUE...PER LATEST GFS/NAM/EC. THE
LOW WEAKENS SOME AS IT SLIDES OVER THE UPPER MISSISSIPPI RIVER
VALLEY TUE NIGHT/WED. MAIN COLD FRONT WITH THIS SYSTEM LOOKS LIKE IT
WILL SLIP THROUGH WITH THE LOW AROUND WED...BUT MODELS KEEP
CONVECTION AT A MINIMUM AROUND IT. RATHER...THE PCPN FOCUS IS
WITH THE LOW LEVEL MOISTURE TRANSPORT...WHICH IS WELL EAST OF THE
COLD FRONT...WRAPPING NORTH/WEST OF THE LOW. SOME MODEL DISAGREEMENT
WITH HOW FAR SOUTH THE AREAS OF SHOWERS/ISOLD STORMS WOULD REACH
WED...WITH THE GFS MORE SOUTH THAN THE EC. IT REMAINS A MESSY
SCENARIO WITH CLARITY LACKING...BUT TRENDS FAVOR THE GREATER PCPN
CHANCES OVER THE NORTHERN 1/2 OF THE FORECAST AREA. WILL LEAN ON
MODEL CONSENSUS FOR THE CHANCES.
TURNING BACK TO TUE...MUCAPES BUILD TO 1500+ J/KG OVER THE EASTERN
1/2 OF THE FORECAST DURING THE AFTERNOON...WITH 0-6 KM SHEAR OF
30-40 KTS. SOME SUGGESTIONS IN THE GFS/NAM OF A PIECE OF UPPER LEVEL
ENERGY ROTATING AROUND THE LOW...WHICH COULD SERVE AS A FOCUS FOR
SHOWER/STORM DEVELOPMENT. ATMOSPHERE LOOKS GOOD FOR STORM PRODUCTION
IF A SPARK FOR CONVECTION IS THERE...WITH A SEVERE THREAT IN THE
EAST TUE AFTERNOON/EARLY EVENING. AGAIN...KEY HERE IS WHERE THE PCPN
FOCUSES WILL BE...INCLUDING ANY MESO SCALE BOUNDARIES AND/OR MCVS
LEFT FROM PREVIOUS CONVECTION.
BETTER AGREEMENT BETWEEN THE GFS AND ECMWF WITH PUSHING THAT
LINGERING LOW EAST/SOUTHEAST ON THU...ALLOWING AN UPPER LEVEL SFC
RIDGE/HIGH PRESSURE SYSTEM TO BUILD INTO THE REGION. SHOULD GET A
COUPLE DRIER DAYS AS A RESULT. HOWEVER...WARM/MOIST AIR ON THE
BACKSIDE OF THE HIGH COUPLED WITH A BIT OF UPPER LEVEL ENERGY COULD
RETURN SOME SHOWERS/STORMS TO THE REGION SAT-SUN.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 800 PM CDT SUN MAY 19 2013
PERIODS OF THUNDERSTORMS ARE EXPECTED THROUGH AT LEAST 06Z. THESE
WILL HAVE HEAVY RAIN AND MAY HAVE DAMAGING WINDS.
&&
.HYDROLOGY...
ISSUED AT 800 PM CDT SUN MAY 19 2013
CONSIDERED AN EXPANSION TO THE FLASH FLOOD WATCH BUT BELIEVE THE
AREA IS WELL PLACED. WITH THE THUNDERSTORMS MOVING IN FROM
IOWA...THERE SHOULD BE A SCOURING EASTWARD AND END TO THE RAIN IN
NERN IA.
EXPECTING THE CEDAR RIVER TO RISE DOWNSTREAM OF OSAGE...CHALRES
CITY WILL SEE A LARGE JUMP IN THE NEXT 12 HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR MNZ079-086-087-094-
095.
IA...FLASH FLOOD WATCH THROUGH MONDAY EVENING FOR IAZ008.
&&
$$
MESOSCALE...BAUMGARDT
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...BAUMGARDT
HYDROLOGY....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1256 PM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT MAY 18 2013
UPPER LEVEL RIDGING TAKING PLACE ACROSS THE UPPER MIDWEST TODAY AS
THE WESTERN CONUS TROUGH DEEPENS. PLENTY OF CONVECTION FIRING UP OFF
THE 850 MB LLJ IN CONJUNCTION WITH A PASSING SHORTWAVE ACROSS
CENTRAL MINNESOTA BACK INTO THE DAKOTAS. THIS ACTIVITY WILL MOSTLY
REMAIN NORTH/NORTHWEST OF THE FORECAST AREA...HOWEVER COULD CLIP
PORTIONS OF NORTH CENTRAL WISCONSIN BY MID TO LATE MORNING. LATEST
RUNS OF THE HRRR AND RAP SHOW CONVECTION WANING BUT POSSIBLY
IMPACTING TAYLOR AND CLARK COUNTIES IN WISCONSIN SO HAVE MAINTAINED
SHOWER/STORM CHANCES THERE. MOIST EASTERLY FLOW AND DECAYING
CIRRUS WILL KEEP SKIES MOSTLY CLOUDY TO OVERCAST THIS
MORNING...BUT AS THE MCS LIFTS NORTH...IT WILL PULL THE WARM FRONT
THROUGH THE AREA. PARTLY TO MOSTLY SUNNY SKIES WILL MOST LIKELY BE
SEEN ACROSS NORTHEAST IOWA WHERE THE FRONT IS ABLE TO CLEAR
THROUGH THE MOST.
DECENT INSTABILITY EXPECTED TODAY IN THE WARM SECTOR...AND MUCAPE
VALUES RANGE FROM 1000 TO 2000 J/KG IN A WEAKLY CAPPED ENVIRONMENT.
LACK OF SURFACE CONVERGENCE HOWEVER PRECLUDES HIGHER PRECIPITATION
CHANCES BUT MOST OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
HINTS THAT CENTRAL WISCONSIN COULD SEE A STRAY SHOWER OR
THUNDERSTORM THIS AFTERNOON. HAVE MAINTAINED PRECIPITATION CHANCES
THERE. OTHERWISE...A WARM DAY ON TAP WITH LOWER TO MID 80S EXPECTED
SOUTH OF I-94.
RELATIVELY QUIET CONDITIONS TONIGHT AS CONVECTION IS EXPECTED TO
REMAIN WELL TO THE WEST AND NORTH. MILD NIGHT WITH SOUTHERLY
FLOW...AND OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013
FOCUS IS ON SEVERE WEATHER CHANCES SUNDAY AND MONDAY AS ACTIVE
WEATHER PATTERN SETS UP ACROSS MUCH OF THE CENTRAL PLAINS.
UPPER LEVEL NEGATIVE TILTED SHORTWAVE TROUGH EJECTS INTO THE CENTRAL
PLAINS ON SUNDAY...MEANWHILE AT THE SURFACE A FEW WAVES OF LOW PRESSURE
SHOULD BE DEVELOPING ACROSS OKLAHOMA INTO NEBRASKA. THIS WILL PULL
NORTH AMPLE GULF OF MEXICO MOISTURE...WITH PWATS INCREASING FROM
AROUND 1 INCH...TO NEARLY 1.75 INCHES...OR 175 PERCENT OF NORMAL.
SURFACE DEWPOINTS WILL RISE INTO THE LOW TO MIDDLE 60S. THERE SHOULD
BE CONVECTION ACROSS WESTERN IOWA INTO SOUTHWEST MINNESOTA EARLY
SUNDAY MORNING...WHICH WILL BE FEEDING OFF THE 850 MB LLJ. THIS
SHOULD WEAKEN AS IT APPROACHES THE WESTERN FORECAST AREA BUT GOOD
CONSENSUS THAT SHOWERS AND THUNDERSTORMS WILL BE AROUND IN THE
MORNING HOURS. THEN...THE BIG QUESTION BECOMES HOW MUCH CLEARING
WE WOULD SEE TO AID IN DESTABILIZATION. ASSUMING WE CLEAR
OUT...0-3KM MUCAPE IS EXPECTED TO INCREASE TO 1500-2000
J/KG...HIGHEST TO THE SOUTH AND WEST. OVERALL THE SHEAR PROFILES
ARE LESS IMPRESSIVE...BUT STILL SHOW 0-3KM BULK SHEAR OF NEARLY 30
KTS. THE ATMOSPHERE DOES REMAIN UNCAPPED SO EXPECTING GOOD CHANCES
OF CONVECTIVE INITIATION WITH ORGANIZED STORMS IN THE FORM OF
SUPERCELLS OR POSSIBLY BOWING SEGMENTS. STRONG TO SEVERE STORMS
WOULD DEVELOP ACROSS WESTERN INTO CENTRAL IOWA...AND TRACK
EAST/NORTHEAST THROUGH THE EVENING HOURS. THE PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WINDS. THE ENVIRONMENT STILL SUPPORTS AN
ISOLATED TORNADO...HOWEVER DEPENDING WHERE A WARM FRONT LAYS IS
MORE UNCERTAIN. 18.00Z GFS HAS THIS BOUNDARY ACROSS CENTRAL
IOWA...BUT 18.00Z ECMWF/NAM HINT THIS COULD BE FURTHER SOUTH.
THE WHOLE SYSTEM EDGES EASTWARD MONDAY...WITH THE BOTH THE
SURFACE AND UPPER LEVEL LOW BECOMING STACKED NEAR SIOUX FALLS SD
BY 12Z MONDAY. PIECES OF ENERGY WILL BE ROTATING THROUGH SOUTHERN
BEND OF THIS TROUGH...LIFTING THROUGH THE AREA DURING THE DAY. THE
SYNOPTIC SETUP IS SLIGHTLY MORE FAVORABLE FOR SEVERE WEATHER FOR
PARTS OF THE AREA. THE SHEAR PROFILES ARE MORE IMPRESSIVE WITH
0-6KM BULK SHEAR VALUES 40 TO 50 KTS ACROSS EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MORE LIMITING FACTOR THIS DAY IS HOW MUCH
DESTABILIZATION WILL OCCUR. THERE COULD BE SCATTERED SHOWERS AND
PLENTY OF CLOUDS AROUND TO LIMIT INSTABILITY. IF WE CAN BREAK OUT
AND FULLY DESTABILIZE...THEN 0-3KM MUCAPE MAY REACH 1500 TO 2000
J/KG. THE ENVIRONMENT SHOULD SUPPORT DISCRETE STORM CELLS...WITH
THE THREATS AGAIN LARGE HAIL AND DAMAGING WINDS.
TUESDAY AND BEYOND...THE UPPER LOW REMAINS NEARLY STATIONARY ACROSS
THE UPPER MIDWEST. THIS GIVES PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE ENTIRE AREA TUESDAY-THURSDAY. MODEL
CONSENSUS PAINTS 30 TO 60 PERCENT CHANCES WHICH IS APPROPRIATE AT
THIS TIME. FEEL THAT MUCH OF NEXT WEEK COULD BE UNSETTLED BUT SEE
LITTLE OPPORTUNITY TO PROVIDE MORE DETAILS IN WHAT PERIODS WOULD BE
MORE ACTIVE...SINCE TIMING PIECES OF ROTATING AROUND THE UPPER LOW
IS DIFFICULT THIS FAR OUT. THE BIGGER STORY WOULD BE THE HEIGHTENED
RISK FOR EXCESSIVE RAINFALL AND LOCALIZED FLOODING IF REPEATED
ROUNDS OF CONVECTION DO IMPACT THE AREA. BY MID-WEEK...SOILS WOULD
BECOME EVEN MORE SATURATED...AND FLASH GUIDANCE FURTHER REDUCED. SEE
HYDROLOGY SECTION BELOW FOR MORE DETAILS ON THAT RISK.
TEMPERATURE-WISE...WARMEST DAYS LOOK TO BE SUNDAY AND MONDAY BEFORE
A GRADUAL COOL DOWN TUESDAY...THEN TO BELOW NORMAL READINGS
WEDNESDAY THROUGH THURSDAY AS THE UPPER LOW DRIFTS OVERHEAD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1256 PM CDT SAT MAY 18 2013
A MOIST AIRMASS FLOWING INTO THE REGION THIS AFTERNOON WILL
PRODUCE SCATTERED TO BROKEN CUMULUS CLOUDS WITH BASES IN THE 2500
TO 3500 FT RANGE. SOUTH WINDS WILL INCREASE THIS AFTERNOON TO
AROUND 10 KTS AT KLSE AND TO AROUND 14 KTS AT KRST. CANNOT RULE
OUT AN ISOLATED SHOWER OR THUNDERSTORM THIS AFTERNOON...BUT THIS
LOOKS UNLIKELY GIVEN THE LACK OF FORCING. CHANCES FOR SHOWERS AND
STORMS INCREASE ACROSS THE REGION ON SUNDAY AS A LOW PRESSURE
SYSTEM DEEPENS OVER THE NORTHERN PLAINS. AT THIS TIME...THE
HIGHEST CHANCES FOR SHOWERS AND POSSIBLY A THUNDERSTORM APPEARS TO
BE AT KRST IN THE 10 TO 14Z TIMEFRAME...THEN ACROSS MUCH OF THE
AREA LATE SUNDAY AFTERNOON INTO SUNDAY EVENING. THE STORMS COULD
PRODUCE PERIODS OF HEAVY RAIN...GUSTY WINDS AND HAIL...ESPECIALLY
DURING THE LATE AFTERNOON AND EVENING ON SUNDAY.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 400 AM CDT SAT MAY 18 2013
HEAVY RAINFALL /2 TO 2.5 INCHES/ FELL FRIDAY ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND COMBINED WITH A RECORD
WET METEOROLOGICAL SPRING...RESULTS IN AN INCREASED RISK FOR
LOCALIZED FLASH FLOODING AS WE HEAD INTO THE LATTER PART OF THE
WEEKEND AND MUCH OF NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS
LOOK TO IMPACT MUCH OF SOUTHEAST MINNESOTA AND NORTHEAST BEGINNING
SUNDAY AFTERNOON. AN ADDITIONAL 1 TO 3 INCHES IS POSSIBLE...AND IF
THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING WOULD OCCUR.
THE 1 AND 3 HOUR FLASH GUIDANCE REMAINS WELL BELOW NORMAL...AND IS
GENERALLY LESS THAN 1 AND 2 INCHES...RESPECTIVELY. WPC CONTINUES THE
SLIGHT RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING EARLY NEXT WEEK
ACROSS MUCH OF CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. A FLASH
FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF THE AREA.
STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...WETENKAMP
HYDROLOGY...ZT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1148 AM CDT SAT MAY 18 2013
UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
MORE AMPLIFIED PATTERN THIS PERIOD AS WESTERN TROF DIGS SOUTHEAST
AND CUTS OFF OVER THE CENTRAL PLAINS. BUILDING HEIGHTS OVER STATE
TODAY AS RIDGE MOVES EAST ACROSS STATE THIS PERIOD WILL LEAD TO
LESSENING CHANCE OF PCPN TODAY. LOCAL RADARS CURRENTLY SHOWING
ISOLD TO SCATTERED SHOWERS OVER NORTHERN WI. TO THE WEST...AREA OF
THUNDERSTORMS MOVING THROUGH MN AND FAR WESTERN WI NORTH OF
STATIONARY/WARM FRONT AND AHEAD OF VORT EJECTING OUT OF UPPER
TROF. MOST TEMPERATURES REMAIN IN THE LOWER 50S AT THIS TIME GIVEN
CLOUDS AND EAST FLOW.
AGAIN...FOCUS OF FORECAST ON PCPN CHANCES AND TEMPS. SHOWERS OVER
NORTHERN WI NORTH OF 850H BAROCLINC ZONE...AREA OF SIG WAA. HAVE
TRENDED TOWARDS A BLEND OF NAM AND EC...AND MESO HRRR MODELS. ALL
SUGGEST PCPN TO SHIFT NORTH THIS MORNING...LEAVING MUCH OF CWA DRY
THIS AFTERNOON. HAVE KEPT A BUFFER OF CHANCE POPS OVER WEST.
RIDGE AXIS PASSES OVERHEAD TONIGHT. HAVE STAYED WITH DRY FORECAST.
ON SUNDAY...PCPN CHANCES INCREASE THROUGH THE DAY AS RIDGE TO BE
EAST OF STATE AND DYNAMICS WITH UPPER TROF COME IN TO PLAY.
STRENGTHENING LLVL FLOW (30 TO 35 KTS AT 850) STRAIGHT OUT OF GULF
TO BRING PW VALUES TO 1.5 INCHES OR GREATER. INSTABILITY INCREASES
WITH MID LEVEL LAPSE RATES AT 7. EC SUGGESTS CAPE VALUES AROUND
1K...NAM SHOWING NORMAL HIGH BIAS. THOUGH MODEL SOUNDINGS SHOW
STRONG CIN OVER EAST THROUGH DAY. HAVE STAYED DRY EAST THROUGH THE AFTN.
TEMPS TO BE A HEADACHE AGAIN TODAY WITH CLOUDS...ONGOING PCPN AND
EAST FLOW OFF LAKE. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST.
WENT A BIT HIGHER ON CLOUDS GIVEN PLENTY OF CIRRUS FLOWING THIS
WAY FROM UPSTREAM CONVECTION. STAYED WITH TEMPS HITTING 80 ON SUN
AS BEST PERFORMING GUIDANCE SUGGESTS...THOUGH UNCERTAINTY SIG
GIVEN POSSIBLE CONVECTION.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
PRECIPITATION CHANCES FOR MUCH OF THE UPCOMING WEEK ARE THE MAIN
CONCERNS DURING THIS PART OF THE FORECAST.
THUNDERSTORMS LOOK LIKE A PRETTY GOOD BET ACROSS THE AREA ON
SUNDAY NIGHT WITH SHORT WAVE ENERGY PASSING THROUGH...AN
APPROACHING SURFACE LOW AND A FRONTAL BOUNDARY MOVING NORTHEAST
ACROSS THE AREA. THOUGH EASTERLY COMPONENT OF SURFACE FLOW OFF
LAKE MICHIGAN MAY LESSEN THE CHANCES FOR STORMS IN THE EAST.
HAVE LIKELY POPS FOR MONDAY AND MONDAY NIGHT. SPC DAY 3 OUTLOOK
HAD CENTRAL AND EAST CENTRAL WISCONSIN IN SLIGHT RISK AS A SURFACE
LOW APPROACHES AND A CLOSED 500MB CYCLONE MAKES ITS WAY TOWARD THE
STATE. STILL QUITE A BIT OF UNCERTAINTY REGARDING THIS SEVERE
THREAT.
THE SURFACE LOW SHOULD MAKE ITS WAY INTO WESTERN WISCONSIN ON
TUESDAY AS BOTH THE SURFACE AND UPPER LEVEL SYSTEMS MAKE THEIR WAY
ACROSS THE WESTERN GREAT LAKES REGION. THUNDER CHANCES SHOULD
DIMINISH AS THE SYSTEMS PASS EAST OF THE FORECAST AREA AND THE
CHANCE OF SHOWERS SHOULD FINALLY COME TO AN END BY THE END OF THE
WORK WEEK.
TEMPERATURES AT THE START OF THE PERIOD ARE EXPECTED TO BE ABOVE
NORMAL BUT COOLER TEMPERATURES ARE FORECAST FOR THE REST OF THE
WEEK...WITH HIGHS MAINLY IN THE 60S EACH DAY.
&&
.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1148 AM CDT SAT MAY 18 2013
WEAKENING BAND OF LIGHT SHOWERS CONTS TO LINGER FROM
NORTH-CENTRAL TO WEST-CENTRAL WI THRU THE AFTERNOON. WHILE MOST
CIGS/VSBYS WL REMAIN VFR...THERE ARE SCATTERED POCKETS OF MVFR CIGS
AS LOW-LEVEL MOISTURE STEADILY INCREASES OVER THE REGION. A NEW
ROUND OF SHWRS/TSTMS ARE EXPECTED TO FIRE OVER THE CNTRL CONUS
THIS EVENING...BUT REMAIN TO OUR WEST DURING THE OVRNGT HOURS.
HOWEVER...SOUTH WINDS ALOFT WL CONT TO PUMP WARM/MOIST AIR INTO WI
WITH DEW PTS CLIMBING INTO THE MID 50S. AS WINDS GO LIGHT TNGT...
ANTICIPATE FOG TO DEVELOP WHICH WOULD SEND VSBYS DOWN INTO THE MVFR
CATEGORY. CANNOT RULE OUT A BRIEF IFR CIG AS WELL OVER THE RHI TAF
SITE WHERE MORE RAIN HAS FALLEN OVER THE PAST 12 HOURS. VFR
CONDITIONS SHOULD RETURN AROUND 15Z SUNDAY AS THE MORNING FOG
BURNS OFF. PCPN CHCS TO INCREASE OVER CNTRL WI BY SUNDAY AFTERNOON
AS A WRMFNT STARTS TO LIFT NWD INTO SW WI.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......AK
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1130 AM CDT SAT MAY 18 2013
.UPDATE...
IT IS DIFFICULT TO TRACK THE LOW CLOUDS ON SATELLITE IMAGERY TODAY
DUE TO THE HIGH CLOUDS STREAMING OVER THEM. HOWEVER...THERE IS A
DISCERNIBLE AREA OF LOW CLOUDS...CONFIRMED BY ASOS/AWOS
OBSERVATIONS...FROM MADISON UP TO JUNEAU AND OVER TO WEST BEND THAT
IS SHIFTING NORTH WITH TIME. CUMULUS CLOUDS HAVE RECENTLY DEVELOPED
OVER SOUTH CENTRAL WI IN AREAS WHERE THE DEWPOINTS ARE ABOUT 59F AND
HIGHER.
THIS HELPS TO DISTINGUISH THE BOUNDARY BETWEEN LAKE-INFLUENCED DRIER
AIR WITH EASTERLY WINDS AND THE STREAM OF MOISTURE FEEDING INTO
SOUTH CENTRAL WI ON SOUTHERLY WINDS. EXPECTING THIS MOIST AIR TO
SPREAD NORTH AND WEST OF MADISON UP TO THE DELLS...BUT NOT SURE
EXACTLY HOW FAR EAST IT WILL GET. IN THE AREA OF CUMULUS
CLOUDS...RAP SOUNDINGS SHOW A SMALL AMOUNT OF CAPE...BUT THE DEPTH
OF THE MOIST LAYER LOOKS VERY SHALLOW. THE 14Z HRRR MODEL NOW BRINGS
LIGHT SHOWERS/TSTORMS BACK INTO AREAS OF SOUTH CENTRAL AND CENTRAL
WI THIS AFTERNOON...SO NOT GIVING UP ON THE SMALL POPS IN OUR
FORECAST.
&&
.AVIATION/18Z TAFS/...
FUEL ALTERNATE CLOUDS...WEAKLY DISCERNIBLE ON VISIBLE SATELLITE
IMAGERY AND CONFIRMED BY ASOS/AWOS OBSERVATIONS FROM MADISON UP TO
JUNEAU AND OVER TO WEST BEND...WILL SHIFT NORTH WITH TIME TODAY.
MVFR CUMULUS CLOUDS HAVE RECENTLY DEVELOPED OVER SOUTH CENTRAL WI IN
AREAS WHERE THE DEWPOINTS ARE ABOUT 59F AND HIGHER.
THIS HELPS TO DISTINGUISH THE BOUNDARY BETWEEN LAKE-INFLUENCED DRIER
AIR WITH EASTERLY WINDS AND THE STREAM OF MOISTURE FEEDING INTO
SOUTH CENTRAL WI ON SOUTHERLY WINDS. EXPECTING THIS MOIST AIR TO
SPREAD NORTH AND WEST OF MADISON UP TO THE DELLS...BUT NOT SURE
EXACTLY HOW FAR EAST IT WILL GET. IN THE AREA OF CUMULUS CLOUDS...
RAP SOUNDINGS SHOW A SMALL AMOUNT OF CAPE...BUT THE DEPTH OF THE
MOIST LAYER LOOKS VERY SHALLOW. THE 14Z HRRR MODEL NOW BRINGS
LIGHT SHOWERS AND ISOLATED TSTORMS BACK INTO AREAS OF SOUTH CENTRAL
AND CENTRAL WI THIS AFTERNOON...SO NOT GIVING UP ON THE SMALL POPS
IN OUR FORECAST. WILL ADD MENTION OF -SHRA BACK INTO MSN TAF.
FOG MAY BE MORE PREVALENT TONIGHT DUE TO LIGHT BOUNDARY LAYER MIXING
BUT TOO MUCH UNCERTAINTY REGARDING CLOUD COVER TO INCLUDE MORE THAN
MVFR VSBYS AT THIS POINT.
&&
.PREV DISCUSSION... /ISSUED 320 AM CDT SAT MAY 18 2013/
AVIATION/12Z TAFS/...BOUNDARY LAYER MIXING AND MOIST LOW TO MID LEVELS
HAS ALLOWED PATCHY LOW CLOUDS TO DEVELOP BY LAKE MI LAST HOUR. WL
LIKELY CONTINUE FOR SEVERAL MORE HOURS AND MAY EXPAND FARTHER
WEST...BUT LOW LEVEL CONVERGENCE WL DIMINISH AS WINDS BEGIN TO
VEER THROUGH THE EARLY MRNG. HENCE WL RETURN TO VFR CONDITIONS BY
MID-MORNING. SOME LIGHT FOG MAY ACCOMPANY LOW CLOUDS BUT BOUNDARY
LAYER MIXING SHOULD PREVENT MORE SIGNIFICANT FOG. FOG MAY BE MORE
PREVALENT TONIGHT DUE TO LIGHT BOUNDARY LAYER MIXING BUT TOO MUCH
UNCERTAINTY REGARDING CLOUD COVER TO INCLUDE MORE THAN MVFR VSBYS
AT THIS POINT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...COLLAR
SUNDAY THROUGH FRIDAY...MBK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
645 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT MAY 18 2013
UPPER LEVEL RIDGING TAKING PLACE ACROSS THE UPPER MIDWEST TODAY AS
THE WESTERN CONUS TROUGH DEEPENS. PLENTY OF CONVECTION FIRING UP OFF
THE 850 MB LLJ IN CONJUNCTION WITH A PASSING SHORTWAVE ACROSS
CENTRAL MINNESOTA BACK INTO THE DAKOTAS. THIS ACTIVITY WILL MOSTLY
REMAIN NORTH/NORTHWEST OF THE FORECAST AREA...HOWEVER COULD CLIP
PORTIONS OF NORTH CENTRAL WISCONSIN BY MID TO LATE MORNING. LATEST
RUNS OF THE HRRR AND RAP SHOW CONVECTION WANING BUT POSSIBLY
IMPACTING TAYLOR AND CLARK COUNTIES IN WISCONSIN SO HAVE MAINTAINED
SHOWER/STORM CHANCES THERE. MOIST EASTERLY FLOW AND DECAYING
CIRRUS WILL KEEP SKIES MOSTLY CLOUDY TO OVERCAST THIS
MORNING...BUT AS THE MCS LIFTS NORTH...IT WILL PULL THE WARM FRONT
THROUGH THE AREA. PARTLY TO MOSTLY SUNNY SKIES WILL MOST LIKELY BE
SEEN ACROSS NORTHEAST IOWA WHERE THE FRONT IS ABLE TO CLEAR
THROUGH THE MOST.
DECENT INSTABILITY EXPECTED TODAY IN THE WARM SECTOR...AND MUCAPE
VALUES RANGE FROM 1000 TO 2000 J/KG IN A WEAKLY CAPPED ENVIRONMENT.
LACK OF SURFACE CONVERGENCE HOWEVER PRECLUDES HIGHER PRECIPITATION
CHANCES BUT MOST OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
HINTS THAT CENTRAL WISCONSIN COULD SEE A STRAY SHOWER OR
THUNDERSTORM THIS AFTERNOON. HAVE MAINTAINED PRECIPITATION CHANCES
THERE. OTHERWISE...A WARM DAY ON TAP WITH LOWER TO MID 80S EXPECTED
SOUTH OF I-94.
RELATIVELY QUIET CONDITIONS TONIGHT AS CONVECTION IS EXPECTED TO
REMAIN WELL TO THE WEST AND NORTH. MILD NIGHT WITH SOUTHERLY
FLOW...AND OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013
FOCUS IS ON SEVERE WEATHER CHANCES SUNDAY AND MONDAY AS ACTIVE
WEATHER PATTERN SETS UP ACROSS MUCH OF THE CENTRAL PLAINS.
UPPER LEVEL NEGATIVE TILTED SHORTWAVE TROUGH EJECTS INTO THE CENTRAL
PLAINS ON SUNDAY...MEANWHILE AT THE SURFACE A FEW WAVES OF LOW PRESSURE
SHOULD BE DEVELOPING ACROSS OKLAHOMA INTO NEBRASKA. THIS WILL PULL
NORTH AMPLE GULF OF MEXICO MOISTURE...WITH PWATS INCREASING FROM
AROUND 1 INCH...TO NEARLY 1.75 INCHES...OR 175 PERCENT OF NORMAL.
SURFACE DEWPOINTS WILL RISE INTO THE LOW TO MIDDLE 60S. THERE SHOULD
BE CONVECTION ACROSS WESTERN IOWA INTO SOUTHWEST MINNESOTA EARLY
SUNDAY MORNING...WHICH WILL BE FEEDING OFF THE 850 MB LLJ. THIS
SHOULD WEAKEN AS IT APPROACHES THE WESTERN FORECAST AREA BUT GOOD
CONSENSUS THAT SHOWERS AND THUNDERSTORMS WILL BE AROUND IN THE
MORNING HOURS. THEN...THE BIG QUESTION BECOMES HOW MUCH CLEARING
WE WOULD SEE TO AID IN DESTABILIZATION. ASSUMING WE CLEAR
OUT...0-3KM MUCAPE IS EXPECTED TO INCREASE TO 1500-2000
J/KG...HIGHEST TO THE SOUTH AND WEST. OVERALL THE SHEAR PROFILES
ARE LESS IMPRESSIVE...BUT STILL SHOW 0-3KM BULK SHEAR OF NEARLY 30
KTS. THE ATMOSPHERE DOES REMAIN UNCAPPED SO EXPECTING GOOD CHANCES
OF CONVECTIVE INITIATION WITH ORGANIZED STORMS IN THE FORM OF
SUPERCELLS OR POSSIBLY BOWING SEGMENTS. STRONG TO SEVERE STORMS
WOULD DEVELOP ACROSS WESTERN INTO CENTRAL IOWA...AND TRACK
EAST/NORTHEAST THROUGH THE EVENING HOURS. THE PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WINDS. THE ENVIRONMENT STILL SUPPORTS AN
ISOLATED TORNADO...HOWEVER DEPENDING WHERE A WARM FRONT LAYS IS
MORE UNCERTAIN. 18.00Z GFS HAS THIS BOUNDARY ACROSS CENTRAL
IOWA...BUT 18.00Z ECMWF/NAM HINT THIS COULD BE FURTHER SOUTH.
THE WHOLE SYSTEM EDGES EASTWARD MONDAY...WITH THE BOTH THE
SURFACE AND UPPER LEVEL LOW BECOMING STACKED NEAR SIOUX FALLS SD
BY 12Z MONDAY. PIECES OF ENERGY WILL BE ROTATING THROUGH SOUTHERN
BEND OF THIS TROUGH...LIFTING THROUGH THE AREA DURING THE DAY. THE
SYNOPTIC SETUP IS SLIGHTLY MORE FAVORABLE FOR SEVERE WEATHER FOR
PARTS OF THE AREA. THE SHEAR PROFILES ARE MORE IMPRESSIVE WITH
0-6KM BULK SHEAR VALUES 40 TO 50 KTS ACROSS EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MORE LIMITING FACTOR THIS DAY IS HOW MUCH
DESTABILIZATION WILL OCCUR. THERE COULD BE SCATTERED SHOWERS AND
PLENTY OF CLOUDS AROUND TO LIMIT INSTABILITY. IF WE CAN BREAK OUT
AND FULLY DESTABILIZE...THEN 0-3KM MUCAPE MAY REACH 1500 TO 2000
J/KG. THE ENVIRONMENT SHOULD SUPPORT DISCRETE STORM CELLS...WITH
THE THREATS AGAIN LARGE HAIL AND DAMAGING WINDS.
TUESDAY AND BEYOND...THE UPPER LOW REMAINS NEARLY STATIONARY ACROSS
THE UPPER MIDWEST. THIS GIVES PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE ENTIRE AREA TUESDAY-THURSDAY. MODEL
CONSENSUS PAINTS 30 TO 60 PERCENT CHANCES WHICH IS APPROPRIATE AT
THIS TIME. FEEL THAT MUCH OF NEXT WEEK COULD BE UNSETTLED BUT SEE
LITTLE OPPORTUNITY TO PROVIDE MORE DETAILS IN WHAT PERIODS WOULD BE
MORE ACTIVE...SINCE TIMING PIECES OF ROTATING AROUND THE UPPER LOW
IS DIFFICULT THIS FAR OUT. THE BIGGER STORY WOULD BE THE HEIGHTENED
RISK FOR EXCESSIVE RAINFALL AND LOCALIZED FLOODING IF REPEATED
ROUNDS OF CONVECTION DO IMPACT THE AREA. BY MID-WEEK...SOILS WOULD
BECOME EVEN MORE SATURATED...AND FLASH GUIDANCE FURTHER REDUCED. SEE
HYDROLOGY SECTION BELOW FOR MORE DETAILS ON THAT RISK.
TEMPERATURE-WISE...WARMEST DAYS LOOK TO BE SUNDAY AND MONDAY BEFORE
A GRADUAL COOL DOWN TUESDAY...THEN TO BELOW NORMAL READINGS
WEDNESDAY THROUGH THURSDAY AS THE UPPER LOW DRIFTS OVERHEAD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 644 AM CDT SAT MAY 18 2013
WITH THE BEST FORCING REMAINING NORTH AND WEST OF THE FORECAST
AREA THROUGH THIS EVENING...KEPT THE TAF SITES DRY WITH CEILINGS
ABOVE 12K FEET. THE MESO MODELS ARE IN GOOD AGREEMENT THAT A SHORT
WAVE TROUGH WILL MOVE NORTHEAST THROUGH THE AREA. THIS WILL BRING
SHOWERS AND THUNDERSTORMS TO NORTHEAST IOWA AND SOUTHEAST
MINNESOTA AFTER 19.09Z. DESPITE THIS PRECIPITATION...SOUNDINGS
SUGGEST THAT THE CEILINGS WILL REMAIN VFR. WHILE THERE MAY BE
SOME BRIEF VISIBILITIES IN THE IFR/MVFR RANGE...TIMING IS VERY
UNCERTAIN...SO LEFT THEM VFR.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 400 AM CDT SAT MAY 18 2013
HEAVY RAINFALL /2 TO 2.5 INCHES/ FELL FRIDAY ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND COMBINED WITH A RECORD
WET METEOROLOGICAL SPRING...RESULTS IN AN INCREASED RISK FOR
LOCALIZED FLASH FLOODING AS WE HEAD INTO THE LATTER PART OF THE
WEEKEND AND MUCH OF NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS
LOOK TO IMPACT MUCH OF SOUTHEAST MINNESOTA AND NORTHEAST BEGINNING
SUNDAY AFTERNOON. AN ADDITIONAL 1 TO 3 INCHES IS POSSIBLE...AND IF
THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING WOULD OCCUR.
THE 1 AND 3 HOUR FLASH GUIDANCE REMAINS WELL BELOW NORMAL...AND IS
GENERALLY LESS THAN 1 AND 2 INCHES...RESPECTIVELY. WPC CONTINUES THE
SLIGHT RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING EARLY NEXT WEEK
ACROSS MUCH OF CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. A FLASH
FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF THE AREA.
STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...BOYNE
HYDROLOGY...ZT
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
642 AM CDT SAT MAY 18 2013
UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
MORE AMPLIFIED PATTERN THIS PERIOD AS WESTERN TROF DIGS SOUTHEAST
AND CUTS OFF OVER THE CENTRAL PLAINS. BUILDING HEIGHTS OVER STATE
TODAY AS RIDGE MOVES EAST ACROSS STATE THIS PERIOD WILL LEAD TO
LESSENING CHANCE OF PCPN TODAY. LOCAL RADARS CURRENTLY SHOWING
ISOLD TO SCATTERED SHOWERS OVER NORTHERN WI. TO THE WEST...AREA OF
THUNDERSTORMS MOVING THROUGH MN AND FAR WESTERN WI NORTH OF
STATIONARY/WARM FRONT AND AHEAD OF VORT EJECTING OUT OF UPPER
TROF. MOST TEMPERATURES REMAIN IN THE LOWER 50S AT THIS TIME GIVEN
CLOUDS AND EAST FLOW.
AGAIN...FOCUS OF FORECAST ON PCPN CHANCES AND TEMPS. SHOWERS OVER
NORTHERN WI NORTH OF 850H BAROCLINC ZONE...AREA OF SIG WAA. HAVE
TRENDED TOWARDS A BLEND OF NAM AND EC...AND MESO HRRR MODELS. ALL
SUGGEST PCPN TO SHIFT NORTH THIS MORNING...LEAVING MUCH OF CWA DRY
THIS AFTERNOON. HAVE KEPT A BUFFER OF CHANCE POPS OVER WEST.
RIDGE AXIS PASSES OVERHEAD TONIGHT. HAVE STAYED WITH DRY FORECAST.
ON SUNDAY...PCPN CHANCES INCREASE THROUGH THE DAY AS RIDGE TO BE
EAST OF STATE AND DYNAMICS WITH UPPER TROF COME IN TO PLAY.
STRENGTHENING LLVL FLOW (30 TO 35 KTS AT 850) STRAIGHT OUT OF GULF
TO BRING PW VALUES TO 1.5 INCHES OR GREATER. INSTABILITY INCREASES
WITH MID LEVEL LAPSE RATES AT 7. EC SUGGESTS CAPE VALUES AROUND
1K...NAM SHOWING NORMAL HIGH BIAS. THOUGH MODEL SOUNDINGS SHOW
STRONG CIN OVER EAST THROUGH DAY. HAVE STAYED DRY EAST THROUGH THE AFTN.
TEMPS TO BE A HEADACHE AGAIN TODAY WITH CLOUDS...ONGOING PCPN AND
EAST FLOW OFF LAKE. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST.
WENT A BIT HIGHER ON CLOUDS GIVEN PLENTY OF CIRRUS FLOWING THIS
WAY FROM UPSTREAM CONVECTION. STAYED WITH TEMPS HITTING 80 ON SUN
AS BEST PERFORMING GUIDANCE SUGGESTS...THOUGH UNCERTAINTY SIG
GIVEN POSSIBLE CONVECTION.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
PRECIPITATION CHANCES FOR MUCH OF THE UPCOMING WEEK ARE THE MAIN
CONCERNS DURING THIS PART OF THE FORECAST.
THUNDERSTORMS LOOK LIKE A PRETTY GOOD BET ACROSS THE AREA ON
SUNDAY NIGHT WITH SHORT WAVE ENERGY PASSING THROUGH...AN
APPROACHING SURFACE LOW AND A FRONTAL BOUNDARY MOVING NORTHEAST
ACROSS THE AREA. THOUGH EASTERLY COMPONENT OF SURFACE FLOW OFF
LAKE MICHIGAN MAY LESSEN THE CHANCES FOR STORMS IN THE EAST.
HAVE LIKELY POPS FOR MONDAY AND MONDAY NIGHT. SPC DAY 3 OUTLOOK
HAD CENTRAL AND EAST CENTRAL WISCONSIN IN SLIGHT RISK AS A SURFACE
LOW APPROACHES AND A CLOSED 500MB CYCLONE MAKES ITS WAY TOWARD THE
STATE. STILL QUITE A BIT OF UNCERTAINTY REGARDING THIS SEVERE
THREAT.
THE SURFACE LOW SHOULD MAKE ITS WAY INTO WESTERN WISCONSIN ON
TUESDAY AS BOTH THE SURFACE AND UPPER LEVEL SYSTEMS MAKE THEIR WAY
ACROSS THE WESTERN GREAT LAKES REGION. THUNDER CHANCES SHOULD
DIMINISH AS THE SYSTEMS PASS EAST OF THE FORECAST AREA AND THE
CHANCE OF SHOWERS SHOULD FINALLY COME TO AN END BY THE END OF THE
WORK WEEK.
TEMPERATURES AT THE START OF THE PERIOD ARE EXPECTED TO BE ABOVE
NORMAL BUT COOLER TEMPERATURES ARE FORECAST FOR THE REST OF THE
WEEK...WITH HIGHS MAINLY IN THE 60S EACH DAY.
&&
.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 632 AM CDT SAT MAY 18 2013
SOME UNCERTAINTY WESTERN SITES WITH PATH/LONGEVITY OF STORMS
ONGOING OVER MN. STORMS TRENDING TO TURN RIGHT THIS
MORNING...THOUGH WEAKEN AS THEY MOVE EAST. BASIC TREND OF THE FORECAST
IS DRY AS RIDGE BUILDS IN. LIGHT WINDS AND AVAILABLE MOISTURE...TO
LEAD TO MVFR FOG OVERNIGHT. INCREASING CHANCE OF STORMS LATE SUN
INTO MON.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......TE
FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE
.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
MORE AMPLIFIED PATTERN THIS PERIOD AS WESTERN TROF DIGS SOUTHEAST
AND CUTS OFF OVER THE CENTRAL PLAINS. BUILDING HEIGHTS OVER STATE
TODAY AS RIDGE MOVES EAST ACROSS STATE THIS PERIOD WILL LEAD TO
LESSENING CHANCE OF PCPN TODAY. LOCAL RADARS CURRENTLY SHOWING
ISOLD TO SCATTERED SHOWERS OVER NORTHERN WI. TO THE WEST...AREA OF
THUNDERSTORMS MOVING THROUGH MN AND FAR WESTERN WI NORTH OF
STATIONARY/WARM FRONT AND AHEAD OF VORT EJECTING OUT OF UPPER
TROF. MOST TEMPERATURES REMAIN IN THE LOWER 50S AT THIS TIME GIVEN
CLOUDS AND EAST FLOW.
AGAIN...FOCUS OF FORECAST ON PCPN CHANCES AND TEMPS. SHOWERS OVER
NORTHERN WI NORTH OF 850H BAROCLINC ZONE...AREA OF SIG WAA. HAVE
TRENDED TOWARDS A BLEND OF NAM AND EC...AND MESO HRRR MODELS. ALL
SUGGEST PCPN TO SHIFT NORTH THIS MORNING...LEAVING MUCH OF CWA DRY
THIS AFTERNOON. HAVE KEPT A BUFFER OF CHANCE POPS OVER WEST.
RIDGE AXIS PASSES OVERHEAD TONIGHT. HAVE STAYED WITH DRY FORECAST.
ON SUNDAY...PCPN CHANCES INCREASE THROUGH THE DAY AS RIDGE TO BE
EAST OF STATE AND DYNAMICS WITH UPPER TROF COME IN TO PLAY.
STRENGTHENING LLVL FLOW (30 TO 35 KTS AT 850) STRAIGHT OUT OF GULF
TO BRING PW VALUES TO 1.5 INCHES OR GREATER. INSTABILITY INCREASES
WITH MID LEVEL LAPSE RATES AT 7. EC SUGGESTS CAPE VALUES AROUND
1K...NAM SHOWING NORMAL HIGH BIAS. THOUGH MODEL SOUNDINGS SHOW
STRONG CIN OVER EAST THROUGH DAY. HAVE STAYED DRY EAST THROUGH THE AFTN.
TEMPS TO BE A HEADACHE AGAIN TODAY WITH CLOUDS...ONGOING PCPN AND
EAST FLOW OFF LAKE. DID NOT STRAY TOO FAR FROM PREVIOUS FORECAST.
WENT A BIT HIGHER ON CLOUDS GIVEN PLENTY OF CIRRUS FLOWING THIS
WAY FROM UPSTREAM CONVECTION. STAYED WITH TEMPS HITTING 80 ON SUN
AS BEST PERFORMING GUIDANCE SUGGESTS...THOUGH UNCERTAINTY SIG
GIVEN POSSIBLE CONVECTION.
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 426 AM CDT SAT MAY 18 2013
PRECIPITATION CHANCES FOR MUCH OF THE UPCOMING WEEK ARE THE MAIN
CONCERNS DURING THIS PART OF THE FORECAST.
THUNDERSTORMS LOOK LIKE A PRETTY GOOD BET ACROSS THE AREA ON
SUNDAY NIGHT WITH SHORT WAVE ENERGY PASSING THROUGH...AN
APPROACHING SURFACE LOW AND A FRONTAL BOUNDARY MOVING NORTHEAST
ACROSS THE AREA. THOUGH EASTERLY COMPONENT OF SURFACE FLOW OFF
LAKE MICHIGAN MAY LESSEN THE CHANCES FOR STORMS IN THE EAST.
HAVE LIKELY POPS FOR MONDAY AND MONDAY NIGHT. SPC DAY 3 OUTLOOK
HAD CENTRAL AND EAST CENTRAL WISCONSIN IN SLIGHT RISK AS A SURFACE
LOW APPROACHES AND A CLOSED 500MB CYCLONE MAKES ITS WAY TOWARD THE
STATE. STILL QUITE A BIT OF UNCERTAINTY REGARDING THIS SEVERE
THREAT.
THE SURFACE LOW SHOULD MAKE ITS WAY INTO WESTERN WISCONSIN ON
TUESDAY AS BOTH THE SURFACE AND UPPER LEVEL SYSTEMS MAKE THEIR WAY
ACROSS THE WESTERN GREAT LAKES REGION. THUNDER CHANCES SHOULD
DIMINISH AS THE SYSTEMS PASS EAST OF THE FORECAST AREA AND THE
CHANCE OF SHOWERS SHOULD FINALLY COME TO AN END BY THE END OF THE
WORK WEEK.
TEMPERATURES AT THE START OF THE PERIOD ARE EXPECTED TO BE ABOVE
NORMAL BUT COOLER TEMPERATURES ARE FORECAST FOR THE REST OF THE
WEEK...WITH HIGHS MAINLY IN THE 60S EACH DAY.
&&
.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1025 PM CDT FRI MAY 17 2013
MVFR CIGS OVERNIGHT ACROSS CENTRAL AND NORTH...WITH OCNL IFR IN
CENTRAL WI. IN ADDITION...AREAS OF FOG MAY DEVELOP WHICH COULD DROP
VSBYS BLO 3 MILES FROM TIME TO TIME BETWEEN 07Z AND 12Z. ISOLATED
STORM NOT OUT OF THE QUESTION...BUT BEST CHANCE WILL BE WEST.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....TE
LONG TERM......MG
AVIATION.......JKL
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
400 AM CDT SAT MAY 18 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT SAT MAY 18 2013
UPPER LEVEL RIDGING TAKING PLACE ACROSS THE UPPER MIDWEST TODAY AS
THE WESTERN CONUS TROUGH DEEPENS. PLENTY OF CONVECTION FIRING UP OFF
THE 850 MB LLJ IN CONJUNCTION WITH A PASSING SHORTWAVE ACROSS
CENTRAL MINNESOTA BACK INTO THE DAKOTAS. THIS ACTIVITY WILL MOSTLY
REMAIN NORTH/NORTHWEST OF THE FORECAST AREA...HOWEVER COULD CLIP
PORTIONS OF NORTH CENTRAL WISCONSIN BY MID TO LATE MORNING. LATEST
RUNS OF THE HRRR AND RAP SHOW CONVECTION WANING BUT POSSIBLY
IMPACTING TAYLOR AND CLARK COUNTIES IN WISCONSIN SO HAVE MAINTAINED
SHOWER/STORM CHANCES THERE. MOIST EASTERLY FLOW AND DECAYING
CIRRUS WILL KEEP SKIES MOSTLY CLOUDY TO OVERCAST THIS
MORNING...BUT AS THE MCS LIFTS NORTH...IT WILL PULL THE WARM FRONT
THROUGH THE AREA. PARTLY TO MOSTLY SUNNY SKIES WILL MOST LIKELY BE
SEEN ACROSS NORTHEAST IOWA WHERE THE FRONT IS ABLE TO CLEAR
THROUGH THE MOST.
DECENT INSTABILITY EXPECTED TODAY IN THE WARM SECTOR...AND MUCAPE
VALUES RANGE FROM 1000 TO 2000 J/KG IN A WEAKLY CAPPED ENVIRONMENT.
LACK OF SURFACE CONVERGENCE HOWEVER PRECLUDES HIGHER PRECIPITATION
CHANCES BUT MOST OF THE DETERMINISTIC AND PROBABILISTIC GUIDANCE
HINTS THAT CENTRAL WISCONSIN COULD SEE A STRAY SHOWER OR
THUNDERSTORM THIS AFTERNOON. HAVE MAINTAINED PRECIPITATION CHANCES
THERE. OTHERWISE...A WARM DAY ON TAP WITH LOWER TO MID 80S EXPECTED
SOUTH OF I-94.
RELATIVELY QUIET CONDITIONS TONIGHT AS CONVECTION IS EXPECTED TO
REMAIN WELL TO THE WEST AND NORTH. MILD NIGHT WITH SOUTHERLY
FLOW...AND OVERNIGHT LOWS IN THE UPPER 50S TO LOWER 60S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 400 AM CDT SAT MAY 18 2013
FOCUS IS ON SEVERE WEATHER CHANCES SUNDAY AND MONDAY AS ACTIVE
WEATHER PATTERN SETS UP ACROSS MUCH OF THE CENTRAL PLAINS.
UPPER LEVEL NEGATIVE TILTED SHORTWAVE TROUGH EJECTS INTO THE CENTRAL
PLAINS ON SUNDAY...MEANWHILE AT THE SURFACE A FEW WAVES OF LOW PRESSURE
SHOULD BE DEVELOPING ACROSS OKLAHOMA INTO NEBRASKA. THIS WILL PULL
NORTH AMPLE GULF OF MEXICO MOISTURE...WITH PWATS INCREASING FROM
AROUND 1 INCH...TO NEARLY 1.75 INCHES...OR 175 PERCENT OF NORMAL.
SURFACE DEWPOINTS WILL RISE INTO THE LOW TO MIDDLE 60S. THERE SHOULD
BE CONVECTION ACROSS WESTERN IOWA INTO SOUTHWEST MINNESOTA EARLY
SUNDAY MORNING...WHICH WILL BE FEEDING OFF THE 850 MB LLJ. THIS
SHOULD WEAKEN AS IT APPROACHES THE WESTERN FORECAST AREA BUT GOOD
CONSENSUS THAT SHOWERS AND THUNDERSTORMS WILL BE AROUND IN THE
MORNING HOURS. THEN...THE BIG QUESTION BECOMES HOW MUCH CLEARING
WE WOULD SEE TO AID IN DESTABILIZATION. ASSUMING WE CLEAR
OUT...0-3KM MUCAPE IS EXPECTED TO INCREASE TO 1500-2000
J/KG...HIGHEST TO THE SOUTH AND WEST. OVERALL THE SHEAR PROFILES
ARE LESS IMPRESSIVE...BUT STILL SHOW 0-3KM BULK SHEAR OF NEARLY 30
KTS. THE ATMOSPHERE DOES REMAIN UNCAPPED SO EXPECTING GOOD CHANCES
OF CONVECTIVE INITIATION WITH ORGANIZED STORMS IN THE FORM OF
SUPERCELLS OR POSSIBLY BOWING SEGMENTS. STRONG TO SEVERE STORMS
WOULD DEVELOP ACROSS WESTERN INTO CENTRAL IOWA...AND TRACK
EAST/NORTHEAST THROUGH THE EVENING HOURS. THE PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WINDS. THE ENVIRONMENT STILL SUPPORTS AN
ISOLATED TORNADO...HOWEVER DEPENDING WHERE A WARM FRONT LAYS IS
MORE UNCERTAIN. 18.00Z GFS HAS THIS BOUNDARY ACROSS CENTRAL
IOWA...BUT 18.00Z ECMWF/NAM HINT THIS COULD BE FURTHER SOUTH.
THE WHOLE SYSTEM EDGES EASTWARD MONDAY...WITH THE BOTH THE
SURFACE AND UPPER LEVEL LOW BECOMING STACKED NEAR SIOUX FALLS SD
BY 12Z MONDAY. PIECES OF ENERGY WILL BE ROTATING THROUGH SOUTHERN
BEND OF THIS TROUGH...LIFTING THROUGH THE AREA DURING THE DAY. THE
SYNOPTIC SETUP IS SLIGHTLY MORE FAVORABLE FOR SEVERE WEATHER FOR
PARTS OF THE AREA. THE SHEAR PROFILES ARE MORE IMPRESSIVE WITH
0-6KM BULK SHEAR VALUES 40 TO 50 KTS ACROSS EASTERN IOWA INTO
SOUTHERN WISCONSIN. THE MORE LIMITING FACTOR THIS DAY IS HOW MUCH
DESTABILIZATION WILL OCCUR. THERE COULD BE SCATTERED SHOWERS AND
PLENTY OF CLOUDS AROUND TO LIMIT INSTABILITY. IF WE CAN BREAK OUT
AND FULLY DESTABILIZE...THEN 0-3KM MUCAPE MAY REACH 1500 TO 2000
J/KG. THE ENVIRONMENT SHOULD SUPPORT DISCRETE STORM CELLS...WITH
THE THREATS AGAIN LARGE HAIL AND DAMAGING WINDS.
TUESDAY AND BEYOND...THE UPPER LOW REMAINS NEARLY STATIONARY ACROSS
THE UPPER MIDWEST. THIS GIVES PERIODIC CHANCES FOR SHOWERS AND
THUNDERSTORMS ACROSS THE ENTIRE AREA TUESDAY-THURSDAY. MODEL
CONSENSUS PAINTS 30 TO 60 PERCENT CHANCES WHICH IS APPROPRIATE AT
THIS TIME. FEEL THAT MUCH OF NEXT WEEK COULD BE UNSETTLED BUT SEE
LITTLE OPPORTUNITY TO PROVIDE MORE DETAILS IN WHAT PERIODS WOULD BE
MORE ACTIVE...SINCE TIMING PIECES OF ROTATING AROUND THE UPPER LOW
IS DIFFICULT THIS FAR OUT. THE BIGGER STORY WOULD BE THE HEIGHTENED
RISK FOR EXCESSIVE RAINFALL AND LOCALIZED FLOODING IF REPEATED
ROUNDS OF CONVECTION DO IMPACT THE AREA. BY MID-WEEK...SOILS WOULD
BECOME EVEN MORE SATURATED...AND FLASH GUIDANCE FURTHER REDUCED. SEE
HYDROLOGY SECTION BELOW FOR MORE DETAILS ON THAT RISK.
TEMPERATURE-WISE...WARMEST DAYS LOOK TO BE SUNDAY AND MONDAY BEFORE
A GRADUAL COOL DOWN TUESDAY...THEN TO BELOW NORMAL READINGS
WEDNESDAY THROUGH THURSDAY AS THE UPPER LOW DRIFTS OVERHEAD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1203 AM CDT SAT MAY 17 2013
GOES SATELLITE IMAGERY SHOWING A LARGE CONVECTIVE COMPLEX WITH
MASSIVE CIRRUS SHIELD HEADING OVER THE TAF SITES AFTER 06Z.
OBSERVATIONS OF CEILINGS ARE SHOWING INCREASING MIDLEVEL CLOUD
COVER NORTH OF THE TAF SITES WITH ERODING LOW-LEVEL IFR CIGS
NORTHWESTWARD. THIS IS THE OPPOSITE OF THE CURRENT TRENDS AT THE
TAF SITES WHICH HAVE IFR BUILDING IN OVERNIGHT.
THE HI RES RAPID REFRESH GUIDANCE CEILING FORECAST...WHICH SEEMS
TO HANDLE THE CURRENT SITUATION AND TREND VERY WELL...CONTINUES TO
ERODE THE IFR CIGS NORTHWEST AND AWAY FROM THE TAF SITES. HOWEVER...THE
TEMP/DEW POINT SPREADS ARE ONLY A FEW DEGREES...ESPECIALLY AT
KRST...THUS ANY COOLING MAY SATURATE THAT CLOUD LAYER.
A SLOW APPROACH TO AN IMPROVEMENT IN THE FORECAST SEEMS PRUDENT.
THUS...HAVE DELAYED ONSET OF IFR FOR THE 06Z TAFS. WILL CONTINUE TO
MONITOR THE TRENDS...BUT IFR MAY BE REMOVED FROM THE FORECAST IN
THE NEXT SEVERAL HOURS.
&&
.HYDROLOGY...SUNDAY AND INTO NEXT WEEK
ISSUED AT 400 AM CDT SAT MAY 18 2013
HEAVY RAINFALL /2 TO 2.5 INCHES/ FELL FRIDAY ACROSS PORTIONS OF
SOUTHEAST MINNESOTA AND NORTHEAST IOWA...AND COMBINED WITH A RECORD
WET METEOROLOGICAL SPRING...RESULTS IN AN INCREASED RISK FOR
LOCALIZED FLASH FLOODING AS WE HEAD INTO THE LATTER PART OF THE
WEEKEND AND MUCH OF NEXT WEEK. PERIODS OF SHOWERS AND THUNDERSTORMS
LOOK TO IMPACT MUCH OF SOUTHEAST MINNESOTA AND NORTHEAST BEGINNING
SUNDAY AFTERNOON. AN ADDITIONAL 1 TO 3 INCHES IS POSSIBLE...AND IF
THIS FALLS IN A SHORT PERIOD...LOCALIZED FLASH FLOODING WOULD OCCUR.
THE 1 AND 3 HOUR FLASH GUIDANCE REMAINS WELL BELOW NORMAL...AND IS
GENERALLY LESS THAN 1 AND 2 INCHES...RESPECTIVELY. WPC CONTINUES THE
SLIGHT RISK OF EXCESSIVE RAINFALL AND FLASH FLOODING EARLY NEXT WEEK
ACROSS MUCH OF CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN. A FLASH
FLOOD WATCH MAY BE NECESSARY FOR PORTIONS OF THE AREA.
STREAMS...CREEKS...AND RIVERS HAVE RESPONDED TO THE RECENT
RAINFALL...MOSTLY WITHIN BANK RISES. HOWEVER...REPEATED ROUNDS OF
HEAVY RAIN COULD PUSH SOME OF THE MORE FLASHY BASINS ACROSS
SOUTHEAST MINNESOTA AND NORTHEAST IOWA TO NEAR FLOOD STAGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...ZT
LONG TERM...ZT
AVIATION...BAUMGARDT
HYDROLOGY...ZT
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
410 AM CDT MON MAY 20 2013
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
STORMS FORMED OVER NORTHEAST OKLAHOMA LATE SUNDAY EVENING...AND
MOVED NORTHEAST INTO SOUTHERN MISSOURI OVERNIGHT. HOWEVER...SHOWERS
HAVE RECENTLY DEVELOPED ALONG THE SOUTHERN EDGE AND ARE MOVING INTO
NORTHERN ARKANSAS. HAVE KEPT SMALL RAIN CHANCES ACROSS THE NORTH
THROUGH THE MORNING HOURS...AS MUCH OF THIS ACTIVITY WILL DISSIPATE
BEFORE NOON.
QUESTION FOR THIS AFTERNOON WILL BE IF ANY DEVELOPMENT OCCURS ON ANY
LINGERING BOUNDARIES LEFT OVER FROM THE OVERNIGHT ACTIVITY. THE NAM
AND NOW THE HRRR IS PICKING UP ON THIS...AHEAD OF ACTIVITY
DEVELOPING OFF LOW LEVEL JET AROUND SUNSET. THIS WILL HAVE TO BE
MONITORED CLOSELY...BECAUSE IF ANY CELL IS DISCRETE...SEVERE WEATHER
WILL BE MAXIMIZED.
THIS EVENING...STORMS WILL FORM ACROSS EASTERN OKLAHOMA INTO
SOUTHERN MISSOURI...AS FRONT INTERACTS WITH LOW LEVEL JET. THE
STORMS WILL SLOWLY MOVE EAST DURING THE LATE EVENING INTO THE
OVERNIGHT HOURS...WITH STRONG TO SEVERE STORMS POSSIBLE. ALSO...WITH
THE SLOW MOTION AND COPIOUS AMOUNTS OF MOISTURE...HEAVY RAINFALL IS
POSSIBLE...ESPECIALLY ACROSS THE NORTHWEST HALF OF THE STATE TONIGHT.
THE FRONT WILL PROGRESS INTO THE STATE TUESDAY...WITH SEVERE
POTENTIAL CONTINUING. HOWEVER...TORNADIC POTENTIAL WILL NOT BE AS
GREAT DUE TO LESSENING SHEAR. FLOODING REMAINS A CONCERN FOR
TUESDAY...AS SEVERAL ROUNDS OF THUNDERSTORMS WILL MOVE ACROSS THE
AREA.
THE RAINFALL WILL BEGIN TO MOVE SOUTHEAST LATE TUESDAY INTO TUESDAY
NIGHT...WITH MUCH OF THE ACTIVITY CONFINED TO THE SOUTHEAST HALF OF
THE STATE WEDNESDAY. HOWEVER...THE FRONT WILL MEANDER AROUND THE
AREA THROUGH THE END OF THE SHORT TERM...WITH SMALL RAIN CHANCES
CONTINUING.
&&
.LONG TERM...FRIDAY THROUGH SUNDAY
COLD FRONT WILL HAVE PUSHED INTO THE STATE FROM THE NE AT THE START
OF THE LONG TERM PERIOD...STALLING ACROSS THE STATE FROM NW TO SE.
MENTION SLIGHT CHANCE POPS WITH THIS FRONT OVER THE STATE FOR
FRI...BUT AN UPPER RIDGE TO THE WEST WILL BEGIN TO SHIFT EAST OVER
THE SRN PLAINS AND SRN MS RIVER VALLEY REGION INTO THIS WEEKEND. AS
A RESULT OF THE RIDGING ALOFT...DECREASE POPS INTO THE WEEKEND...AS
WELL AS INCREASING TEMPS ABOVE NORMAL BY LATE IN THE FORECAST.
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...58 / LONG TERM...62
AREA FORECAST DISCUSSION
NWS TAUNTON MA
339 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WARM FRONT LIFTING THROUGH THE REGION WILL BRING A FEW SHOWERS
OR THUNDERSTORMS TODAY AS IT HEADS INTO CENTRAL NEW ENGLAND. THE
FRONT WILL DROP BACK SOUTH ON TUESDAY RESULTING IN BRIEFLY COOLER
WEATHER...BEFORE WARM AND HUMID CONDITIONS RETURN WEDNESDAY AND
THURSDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS. IT WILL TURN
COOLER AND LESS HUMID NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
315 AM UPDATE...
LAST OF SHOWERS WERE EXITING CAPE COD AND ISLANDS EARLY THIS
MORNING. CLOUDS REMAIN LOCKED IN WITH PATCHY FOG AND DRIZZLE...
WHICH WILL PERSIST THROUGH MID MORNING. THEREAFTER MODEL CROSS
SECTIONS SHOW SOME DRYING THROUGH COLUMN AS WEAK WARM FRONT LIFTS
TO OUR N. THIS SHOULD ALLOW FOR BREAKS OF SUNSHINE TO DEVELOP
LATER THIS MORNING AND THIS AFTERNOON FOR MUCH OF SOUTHERN NEW
ENGLAND. EXCEPTION WILL BE NEAR S COAST...CAPE COD AND ISLANDS
WHERE MARINE LAYER SHOULD HOLD STRONG GIVEN SW FLOW.
POTENTIAL FOR CONVECTION THIS AFTERNOON IS LIMITED BY LACK OF
INSTABILITY AS SB CAPES ONLY FORECAST TO BE AS HIGH AS 500
J/KG...WEAK MID LEVEL LAPSE RATES OF LESS THAN 5C/KM...AND
MARGINAL 0-6KM SHEAR OF 30KT. THAT SAID WE DO EXPECT TO SEE AT
LEAST WIDELY SCATTERED SHOWERS/STORMS DEVELOP ACROSS INTERIOR.
MAINTAINED CHANCE POPS AWAY FROM S COAST...ALTHOUGH BEST CHANCE
LOOKS TO BE ACROSS SW NH AND NW MA. HRRR SHOWS SCATTERED ACTIVITY
DEVELOPING IN THOSE AREAS AFTER 18Z.
CERTAINLY LOOKS LIKE A WARMER AND SOMEWHAT MORE HUMID DAY WITH
HIGHS RANGING FROM 60S ALONG S COAST TO 70S AND LOWER 80S
ELSEWHERE. USED A BLEND OF NAM/GFS MOS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
WARM FRONT STALLS ACROSS CENTRAL NEW ENGLAND TONIGHT. THIS WILL
MAINTAIN LIGHT S/SW FLOW ACROSS REGION AND WITH PLENTY OF LOW
LEVEL MOISTURE...CONFIDENCE IS HIGH ON SEEING LOW CLOUDS/FOG AND
POSSIBLY DRIZZLE SPREAD INLAND FROM COAST. POTENTIAL IS THERE FOR
AREAS OF DENSE FOG...ESPECIALLY AROUND CAPE COD AND ISLANDS.
OTHERWISE NO SIGNIFICANT RAINFALL IS EXPECTED AS BEST DYNAMICS
STAY TO OUR N AND W. RELATIVELY MILD NIGHT WITH LOWS HOLDING IN
50S/LOWER 60S...WHICH IS CLOSER TO NAM MOS.
WEAK UPPER RIDGE BUILDING ACROSS NEW YORK STATE WILL FORCE FRONT
BACK SOUTHWARD TUE AS A BACKDOOR COLD FRONT. MODELS IN GOOD
AGREEMENT IN DROPPING FRONT THROUGH TUE AFTERNOON...BUT GFS SEEMS
TO OVERDO CONVECTION RIDING E ALONG BOUNDARY FROM GREAT LAKES. NAM
SEEMS MUCH MORE REASONABLE IN STABILIZING AIRMASS OVER SOUTHERN
NEW ENGLAND AS FLOW TURNS MORE E/SE AND FOCUSES ANY CONVECTION TO
OUR W/N WHERE IT BECOMES MORE UNSTABLE. WE ARE NOT THINKING WE
WILL SEE MUCH IN WAY OF SHOWERS/STORMS DEVELOP...ALTHOUGH IT IS
POSSIBLE A FEW SHOWERS MAKE IT INTO WESTERN NEW ENGLAND BY END OF
DAY.
SHOULD BE WIDE RANGE IN TEMPERATURES TUE DUE TO ONSHORE FLOW...
FROM LOWER 60S ALONG E MA COASTLINE INCLUDING CAPE COD TO UPPER
70S ACROSS CT RIVER VALLEY. LEANED MORE TOWARD NAM MOS WHICH
CAPTURES THIS WELL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGHLIGHTS...
* WARM AND MUGGY WED/THU THEN TURNING COOLER AND LESS HUMID FRI
* SCATTERED SHOWERS AND THUNDERSTORMS WED AND THU
* DRY BUT COOLER THAN NORMAL FOR MEMORIAL DAY WEEKEND
GOOD OVERALL AGREEMENT ON THE LARGE SCALE FLOW INCLUDING FRONTAL
POSITIONS FROM THE 12Z/19 GEFS AND ECENS. BOTH OF THESE ENSEMBLE
DATA SETS HAVE A BACKDOOR FRONT SAGGING SOUTHWARD THROUGH THE
SOUTHERN NEW ENGLAND TUE NIGHT THEN LIFTING NORTH OF THE REGION WED
AND THU WITH TRUE WARM SECTOR OVERSPREADING THE AREA. BOTH ENSEMBLES
OFFER +16C AIRMASS AT 850 MB AND +20C AT 925 MB OVER THE REGION
WED. THUS POTENTIAL FOR TEMPS TO SOAR INTO THE 80S BOTH DAYS IF
SUNSHINE DEVELOPS. IT WILL BE MUGGY AS WELL WITH DEW PTS IN THE 60S.
THIS WILL RESULT IN WARM NIGHTS /WED AND THU/ ALONG WITH PATCHY FOG.
SCATTERED SHOWERS AND THUNDERSTORMS LIKELY BOTH WED AND THU GIVEN
WARM SECTOR OVER THE AREA BOTH DAYS. ALSO MODELS IN GOOD AGREEMENT
ON CONVECTION ALONG OR NEAR THE WARM FRONT TUE EVENING/NIGHT.
CONVECTION WILL BE MORE WIDESPREAD DURING PEAK HEATING HOURS OF THE
AFTERNOON AND LINGERING INTO THE EARLY EVENING BOTH DAYS. ENSEMBLES
SUGGEST INSTABILITY GREATER WED (MEAN CAPE ABOUT 1000J/KG) THAN THU.
HOWEVER APPROACHING COLD FRONT WILL YIELD GREATER FRONTAL
CONVERGENCE THU ALONG WITH STRONGER JET DYNAMICS /0-6KM DEEP LAYER
SHEAR/...SO CONVECTION MAY BE MORE ORGANIZED/NUMEROUS THU THAN WED.
IN ADDITION GEFS SUGGEST INSTABILITY RIDGE ACROSS NY/PA AND NJ.
THEREFORE WESTERN NEW ENGLAND HAS GREATEST RISK FOR STRONG TO
PERHAPS SEVERE TSTMS WED AND THU. GIVEN INSTABILITY AND PWATS OF +1
TO +2 STD HEAVY DOWNPOURS ARE POSSIBLE WITH ANY CONVECTION.
GOOD MODEL AGREEMENT THAT FRONTAL PASSAGE WILL OCCUR SOMETIME LATE
THU OR FRI. 00Z GFS SLOWER WITH FROPA AS IT DEVELOPS A WAVE ALONG
THE FRONT. AT THIS TIME RANGE PREFER NOT TO CHASE A SINGLE
DETERMINISTIC SOLUTION SO WILL FOLLOW PRES PATTERN FROM GEFS AND
ECENS. THIS SUGGEST FRI WILL BE OUR TRANSITION DAY FROM WARM AND
MUGGY TO A DRY...MUCH COOLER AND LESS HUMID AIRMASS FOR MEMORIAL DAY
WEEKEND. IN FACT BY SAT BOTH GEFS AND ECENS HAVE A 1030MB HIGH
SETTLING OVER THE GREAT LAKES WITH CORE OF THIS ANOMALOUS COOL
AIRMASS /850 TEMPS 0C TO +2C/ ACROSS NORTHERN MA/SOUTHWEST NH...THEN
SLOWLY MODERATING BY MON. HENCE MILD DAYS BUT COOL NIGHTS. IN FACT
THERE COULD BE SOME PATCHY FROST ACROSS NORTHWEST MA INTO SOUTHWEST
NH WITH TEMPS DIPPING INTO THE MU30S SAT AND SUN MORNING!
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
MODERATE CONFIDENCE THROUGH TUE.
WIDESPREAD IFR/LIFR THROUGH 12Z IN LOW CLOUDS/FOG/DRIZZLE. GRADUAL
IMPROVEMENT TO MVFR EXPECTED 12Z-15Z AND EVENTUALLY VFR BY 18Z
EXCEPT AROUND CAPE COD AND ISLANDS WHERE IFR LIKELY TO PERSIST ALL
DAY. SCT SHOWERS WILL REFORM ACROSS INTERIOR AFTER 18Z WITH
ISOLATED THUNDER ALSO POSSIBLE.
SHOULD SEE RAPID DETERIORATION THIS EVENING TO IFR/LIFR 23Z-03Z
AS LOW CLOUDS/FOG/DRIZZLE RETURN IN LIGHT ONSHORE FLOW. WILL BE
HARDER FOR IFR TO ERODE TUE WITH PERSISTENT E/SE WIND...BUT EXPECT
ALL BUT CAPE/ISLANDS TO IMPROVE TO MVFR CIGS BY 18Z.
KBOS TERMINAL...MODERATE CONFIDENCE. CONFIDENT ON TIMING OF
IMPROVEMENT THIS MORNING...BUT CIGS MAY ONLY LIFT TO 025 THROUGH
18Z.
KBDL TERMINAL...MODERATE CONFIDENCE. MAY BE 2-3 HOURS TOO FAST ON
IMPROVEMENT TO MVFR CIGS THIS MORNING.
OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...
TUESDAY THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. VERY
UNSETTLED PATTERN WITH VARIABILITY BETWEEN VFR CONDITIONS AND
MVFR/IFR CONDITIONS IN SHRA/TSRA/FOG. A FEW STRONG TO SEVERE TSTMS
POSSIBLE WED AND THU.
FRIDAY...MODERATE CONFIDENCE. CONDITIONS SHOULD IMPROVE ALONG WITH
A WIND SHIFT FROM WEST TO EAST AS COLD FRONT MOVES THROUGH REGION.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH TUE.
WARM FRONT LIFTS N OF COASTAL WATERS TODAY AND STALLS OVER CENTRAL
NEW ENGLAND. LIGHT S/SW FLOW DEVELOPS ACROSS WATERS BUT SEAS
SLOWLY BUILD IN SOUTHERLY SWELL...MOST NOTABLY ACROSS S COASTAL
WATERS WHERE SCA REMAINS POSTED. ALTHOUGH SW FLOW IS MODEST AT
BEST IT SHOULD STILL CREATE STEEP WAVES ON BUZZARDS BAY AND
VINEYARD SOUND DURING OUTGOING TIDE THIS AFTERNOON...SO MAINTAINED
SCA FOR THOSE AREAS AS WELL.
EXPECT AREAS OF DENSE FOG TONIGHT INTO TUE WITH PERSISTENT SW
FLOW...ESPECIALLY AROUND CAPE COD AND ISLANDS. FRONT DROPS BACK S
TUE AND SHIFTS WINDS TO E/SE...SO VSBYS SHOULD IMPROVE TUE
AFTERNOON. SEAS SHOULD BEGIN TO SUBSIDE AS WELL DUE TO DECAYING
SOUTHERLY SWELL.
OUTLOOK...TUESDAY THROUGH FRIDAY...
TUESDAY NIGHT... BACKDOOR FRONT SLIPS ACROSS THE AREA WITH NE WINDS
LIKELY OVER THE NORTHERN WATERS AND SW WINDS ACROSS SOUTHERN WATERS.
RAIN AND FOG WILL REDUCE VSBY. MODEST WIND AT BEST WITH MARGINAL
SWELL.
WED AND THU... WARM FRONT LIFTS NORTH OF THE AREA WITH MODEST SSW
WINDS DEVELOPING ACROSS THE WATERS. SSW WINDS MAY INCREASE TO 20-25
KT FROM LATE WED INTO THU AHEAD OF APPROACHING COLD FRONT. SHOWERS
AND TSTMS SHOULD BE MOST NUMEROUS THU WITH APPROACHING COLD FRONT.
FRIDAY...COLD FRONT ALONG WITH WIND SHIFT FROM SSW TO WNW SHOULD
COMMENCE. VSBY WILL IMPROVE WITH THE WIND.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 AM EDT TUESDAY
FOR ANZ233>235-237.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT TUESDAY
FOR ANZ254-255.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT TUESDAY
FOR ANZ256.
&&
$$
SYNOPSIS...NOCERA/JWD
NEAR TERM...JWD
SHORT TERM...JWD
LONG TERM...NOCERA
AVIATION...NOCERA/JWD
MARINE...NOCERA/JWD
AREA FORECAST DISCUSSION
NWS TAUNTON MA
317 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WARM FRONT LIFTING THROUGH THE REGION WILL BRING A FEW SHOWERS
OR THUNDERSTORMS TODAY AS IT HEADS INTO CENTRAL NEW ENGLAND. THE
FRONT WILL DROP BACK SOUTH ON TUESDAY RESULTING IN BRIEFLY COOLER
WEATHER...BEFORE WARM AND HUMID CONDITIONS RETURN WEDNESDAY AND
THURSDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS. IT WILL TURN
COOLER AND LESS HUMID NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
315 AM UPDATE...
LAST OF SHOWERS WERE EXITING CAPE COD AND ISLANDS EARLY THIS
MORNING. CLOUDS REMAIN LOCKED IN WITH PATCHY FOG AND DRIZZLE...
WHICH WILL PERSIST THROUGH MID MORNING. THEREAFTER MODEL CROSS
SECTIONS SHOW SOME DRYING THROUGH COLUMN AS WEAK WARM FRONT LIFTS
TO OUR N. THIS SHOULD ALLOW FOR BREAKS OF SUNSHINE TO DEVELOP
LATER THIS MORNING AND THIS AFTERNOON FOR MUCH OF SOUTHERN NEW
ENGLAND. EXCEPTION WILL BE NEAR S COAST...CAPE COD AND ISLANDS
WHERE MARINE LAYER SHOULD HOLD STRONG GIVEN SW FLOW.
POTENTIAL FOR CONVECTION THIS AFTERNOON IS LIMITED BY LACK OF
INSTABILITY AS SB CAPES ONLY FORECAST TO BE AS HIGH AS 500
J/KG...WEAK MID LEVEL LAPSE RATES OF LESS THAN 5C/KM...AND
MARGINAL 0-6KM SHEAR OF 30KT. THAT SAID WE DO EXPECT TO SEE AT
LEAST WIDELY SCATTERED SHOWERS/STORMS DEVELOP ACROSS INTERIOR.
MAINTAINED CHANCE POPS AWAY FROM S COAST...ALTHOUGH BEST CHANCE
LOOKS TO BE ACROSS SW NH AND NW MA. HRRR SHOWS SCATTERED ACTIVITY
DEVELOPING IN THOSE AREAS AFTER 18Z.
CERTAINLY LOOKS LIKE A WARMER AND SOMEWHAT MORE HUMID DAY WITH
HIGHS RANGING FROM 60S ALONG S COAST TO 70S AND LOWER 80S
ELSEWHERE. USED A BLEND OF NAM/GFS MOS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
WARM FRONT STALLS ACROSS CENTRAL NEW ENGLAND TONIGHT. THIS WILL
MAINTAIN LIGHT S/SW FLOW ACROSS REGION AND WITH PLENTY OF LOW
LEVEL MOISTURE...CONFIDENCE IS HIGH ON SEEING LOW CLOUDS/FOG AND
POSSIBLY DRIZZLE SPREAD INLAND FROM COAST. POTENTIAL IS THERE FOR
AREAS OF DENSE FOG...ESPECIALLY AROUND CAPE COD AND ISLANDS.
OTHERWISE NO SIGNIFICANT RAINFALL IS EXPECTED AS BEST DYNAMICS
STAY TO OUR N AND W. RELATIVELY MILD NIGHT WITH LOWS HOLDING IN
50S/LOWER 60S...WHICH IS CLOSER TO NAM MOS.
WEAK UPPER RIDGE BUILDING ACROSS NEW YORK STATE WILL FORCE FRONT
BACK SOUTHWARD TUE AS A BACKDOOR COLD FRONT. MODELS IN GOOD
AGREEMENT IN DROPPING FRONT THROUGH TUE AFTERNOON...BUT GFS SEEMS
TO OVERDO CONVECTION RIDING E ALONG BOUNDARY FROM GREAT LAKES. NAM
SEEMS MUCH MORE REASONABLE IN STABILIZING AIRMASS OVER SOUTHERN
NEW ENGLAND AS FLOW TURNS MORE E/SE AND FOCUSES ANY CONVECTION TO
OUR W/N WHERE IT BECOMES MORE UNSTABLE. WE ARE NOT THINKING WE
WILL SEE MUCH IN WAY OF SHOWERS/STORMS DEVELOP...ALTHOUGH IT IS
POSSIBLE A FEW SHOWERS MAKE IT INTO WESTERN NEW ENGLAND BY END OF
DAY.
SHOULD BE WIDE RANGE IN TEMPERATURES TUE DUE TO ONSHORE FLOW...
FROM LOWER 60S ALONG E MA COASTLINE INCLUDING CAPE COD TO UPPER
70S ACROSS CT RIVER VALLEY. LEANED MORE TOWARD NAM MOS WHICH
CAPTURES THIS WELL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGHLIGHTS...
* SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE WED-THU
* COOLER...LESS HUMID FOR THE WEEKEND
MODELS ARE IN DECENT AGREEMENT THROUGH MUCH OF THE LONG TERM. THERE
ARE SOME TIMING DISCREPANCIES THROUGHOUT THE LONG TERM BETWEEN THE
ECMWF AND THE GFS...AS WELL AS THE NAM TUE. THE NAM IS QUICKER THAN
EITHER THE ECMWF OR GFS WITH A WARM FRONT MOVING NORTH THROUGH THE
REGION TUES. THE GFS THEN WHISKS ALONG AND BRINGS LOW PRESSURE
THROUGH QUEBEC MORE QUICKLY WED WITH A COLD FRONT MOVING THROUGH
SOUTHERN NEW ENGLAND SOONER ON THU THAN THE ECMWF. HOWEVER...THE
OVERALL SYNOPTIC PATTERN IS FAIRLY WELL IN LINE THROUGHOUT THE
PERIOD. GENERALLY EXPECTING A MORE UNSETTLED BUT WARMER PATTERN
THROUGH THE WORK WEEK...WITH QUIETER BUT COOLER WEATHER FRIDAY AND
INTO THE WEEKEND.
WEDNESDAY AND THURSDAY...THERE ARE SOME TIMING QUESTIONS HERE
REGARDING THE LOW PRESSURE SYSTEM MOVING THROUGH SOUTHERN CANADA
AND THE ACCOMPANYING COLD FRONT THAT WILL MOVE THROUGH SOUTHERN
NEW ENGLAND. NEITHER THE GFS NOR THE ECMWF HAVE THE COLD FRONT
MOVING THROUGH SOUTHERN NEW ENGLAND UNTIL AFTER MIDNIGHT THURSDAY
NIGHT. HOWEVER...THE DIFFERENCES IN THE POSITION AND PATH OF THE
LOW PRESSURE COULD IMPACT THE AMOUNT OF CLOUDS AS WELL AS THE BEST
PLACE FOR SHOWERS AND THUNDERSTORMS ACROSS THE REGION. FOR NOW
HAVE OPTED FOR HIGH END CHANCE POPS WITH SLIGHT CHANCE TO CHANCE
THUNDER PRETTY MUCH ACROSS THE BOARD. INSTABILITY PARAMETERS ARE
SUCH THAT EXPECT THUNDER TO BE FAIRLY WIDESPREAD.
FRIDAY...AS MENTIONED ABOVE...THE COLD FRONT WILL MOVE THROUGH
SOUTHERN NEW ENGLAND SOMETIME ON FRIDAY...WITH THE GFS BRINGING IT
THROUGH THE AREA BETWEEN MIDNIGHT AND 6 AM AND THE ECMWF BRINGING IT
THROUGH ABOUT MIDDAY. THE TIMING OF THIS FRONT WILL HAVE A LARGE
IMPACT ON THE WEATHER AS MOSTLY CLOUDY SKIES AND WARMER...MORE HUMID
AIR CAN BE FOUND AHEAD OF THE FRONT WHILE CLEARING SKIES AND
COOLER...LESS HUMID AIR WILL MOVE IN BEHIND THE FRONT. IF THIS
OCCURS DURING THE EARLY MORNING...HIGH TEMPERATURES WILL BE LOWER
BUT THE AREA WILL SEE MORE SUN...WHILE IF IT DOESN/T OCCUR UNTIL
MIDDAY COULD SEE WARMER HIGHS BUT LESS SUN.
SATURDAY AND SUNDAY...WITH HIGH PRESSURE DOMINANT OVER SOUTHERN NEW
ENGLAND...EXPECT A PLEASANT WEEKEND WITH HIGH TEMPERATURES A FEW
DEGREES BELOW NORMAL AND SUNNY SKIES.
&&
.AVIATION /07Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
MODERATE CONFIDENCE THROUGH TUE.
WIDESPREAD IFR/LIFR THROUGH 12Z IN LOW CLOUDS/FOG/DRIZZLE. GRADUAL
IMPROVEMENT TO MVFR EXPECTED 12Z-15Z AND EVENTUALLY VFR BY 18Z
EXCEPT AROUND CAPE COD AND ISLANDS WHERE IFR LIKELY TO PERSIST ALL
DAY. SCT SHOWERS WILL REFORM ACROSS INTERIOR AFTER 18Z WITH
ISOLATED THUNDER ALSO POSSIBLE.
SHOULD SEE RAPID DETERIORATION THIS EVENING TO IFR/LIFR 23Z-03Z
AS LOW CLOUDS/FOG/DRIZZLE RETURN IN LIGHT ONSHORE FLOW. WILL BE
HARDER FOR IFR TO ERODE TUE WITH PERSISTENT E/SE WIND...BUT EXPECT
ALL BUT CAPE/ISLANDS TO IMPROVE TO MVFR CIGS BY 18Z.
KBOS TERMINAL...MODERATE CONFIDENCE. CONFIDENT ON TIMING OF
IMPROVEMENT THIS MORNING...BUT CIGS MAY ONLY LIFT TO 025 THROUGH
18Z.
KBDL TERMINAL...MODERATE CONFIDENCE. MAY BE 2-3 HOURS TOO FAST ON
IMPROVEMENT TO MVFR CIGS THIS MORNING.
OUTLOOK...WEDNESDAY THROUGH FRIDAY...
WEDNESDAY THROUGH THURSDAY NIGHT...LOW TO MODERATE CONFIDENCE.
VERY UNSETTLED PATTERN WITH VARIABILITY BETWEEN VFR CONDITIONS AND
MVFR/IFR CONDITIONS IN SHRA/TSRA/FOG.
FRIDAY...MODERATE CONFIDENCE. CONDITIONS SHOULD IMPROVE TO VFR FROM
WEST TO EAST AS COLD FRONT MOVES THROUGH REGION.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH TUE.
WARM FRONT LIFTS N OF COASTAL WATERS TODAY AND STALLS OVER CENTRAL
NEW ENGLAND. LIGHT S/SW FLOW DEVELOPS ACROSS WATERS BUT SEAS
SLOWLY BUILD IN SOUTHERLY SWELL...MOST NOTABLY ACROSS S COASTAL
WATERS WHERE SCA REMAINS POSTED. ALTHOUGH SW FLOW IS MODEST AT
BEST IT SHOULD STILL CREATE STEEP WAVES ON BUZZARDS BAY AND
VINEYARD SOUND DURING OUTGOING TIDE THIS AFTERNOON...SO MAINTAINED
SCA FOR THOSE AREAS AS WELL.
EXPECT AREAS OF DENSE FOG TONIGHT INTO TUE WITH PERSISTENT SW
FLOW...ESPECIALLY AROUND CAPE COD AND ISLANDS. FRONT DROPS BACK S
TUE AND SHIFTS WINDS TO E/SE...SO VSBYS SHOULD IMPROVE TUE
AFTERNOON. SEAS SHOULD BEGIN TO SUBSIDE AS WELL DUE TO DECAYING
SOUTHERLY SWELL.
OUTLOOK...WEDNESDAY THROUGH FRIDAY...
WEDNESDAY...SEAS INCREASE AS HIGH PRESSURE MOVES AWAY FROM THE
WATERS. SOUTHERLY WINDS GUST TO NEAR 25 KTS. SCA WILL BE NECESSARY
FOR SEAS IF NOT WINDS AS WELL. VISIBILITY MAY BE LIMITED AT TIMES
IN SCATTERED SHOWERS AND THUNDERSTORMS.
THURSDAY...SEAS REMAIN ABOVE 5 FEET AS LOW PRESSURE MOVES INTO THE
MARITIMES AND A COLD FRONT APPROACHES THE WATERS. SOUTHERLY WINDS
GUST TO NEAR 25 KTS. SCA WILL BE NECESSARY FOR SEAS IF NOT WINDS AS
WELL. VISIBILITY MAY BE LIMITED AT TIMES IN SCATTERED SHOWERS AND
THUNDERSTORMS. WINDS INCREASE OVERNIGHT WITH APPROACHING COLD FRONT.
FRIDAY...SEAS BEGIN TO DIMINISH AS HIGH PRESSURE BUILDS OVER THE
WATERS. WINDS INCREASE TO 25 TO 30KTS WITH COLD FRONTAL PASSAGE.
WINDS SHOULD BE OUT OF THE SOUTH AHEAD OF THE FRONT...SHIFTING TO
THE NORTHWEST BEHIND THE FRONT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 6 AM THIS MORNING
TO 2 AM EDT TUESDAY FOR ANZ233>235-237.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT TUESDAY
FOR ANZ254-255.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT TUESDAY
FOR ANZ256.
&&
$$
SYNOPSIS...NOCERA/JWD
NEAR TERM...JWD
SHORT TERM...JWD
LONG TERM...RLG
AVIATION...NOCERA/JWD
MARINE...NOCERA/JWD
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
328 AM EDT MON MAY 20 2013
.SHORT TERM /TODAY THROUGH TUESDAY NIGHT/...
THE IMMEDIATE SHORT TERM WILL BE SPENT DEALING WITH RESULTS OF A
NEARLY 24 HOUR LONG RAINFALL EVENT WHICH INCLUDES THE DEVELOPMENT
OF LOW CLOUDS AND FOG. GENESIS REGION FOR THIS IS THE CAROLINAS
AND OVER THE LAST SEVERAL HOURS HAS SPREAD WEST INTO THE NORTHEAST
MOUNTAINS AND JUST NOW ENTERING INTO THE REMAINDER OF NORTH
GEORGIA. NAM12 VERY BULLISH ON FOG DEVELOPMENT THROUGH THIS
MORNING WITH WIDESPREAD CONDENSATION PRESSURE DEFICIT VALUES RIGHT
AROUND ZERO. GFS NOT NEARLY THIS AGGRESSIVE BUT BASED ON
OBS...LOOKS LIKE NAM12 IS INITIALIZING BETTER AT THIS POINT AND
WILL FAVOR ITS SOLUTION.
FOG AND LOW CLOUDS TO SLOWLY LIFT DURING THE MORNING HOURS BUT
ENOUGH LOW LEVEL MOISTURE REMAINS TO MAINTAIN A CIG DECK FOR MUCH
OF THE DAY. AS FAR AS POPS AREA CONCERNED...MODELS IN AGREEMENT
THAT UPPER RIDGE AXIS WILL SHIFT EASTWARD...GETTING US OUT OF THE
BELT OF NW FLOW AND LIMITING EFFECTS FROM ANY IMPULSES TO OUR
EXTREME EASTERN SECTIONS. AM A LITTLE CONCERNED THAT WEAK SYNOPTIC
WINS WILL ALLOW SEA BREEZE AND DEVELOPING OUTFLOWS PROPAGATE WEST
AND BRING SHOWERS AND THUNDERSTORMS WITH THEM SO HAVE GONE ABOVE
GUIDANCE FORM MY SOUTHEAST ZONES TODAY. HRRR SHOWS SEPARATE
SECTION DEVELOPING DURING THE AFTERNOON. ALTHOUGH THIS REGION IS
CLOSER TO UPPER RIDGE...STRENGTH OF THIS FEATURE IS LIMITED AND
WILL NEED TO CARRY AT LEAST SLIGHT CHANCE POPS ALL ZONES.
LOW CLODS AND FOG NOT QUITE AS PROMINENT IN THE MODELS TUESDAY
MORNING BUT SATELLITE LOOKS LIKE DECENT DEVELOPMENT OVER THE EASTERN
THIRD OF THE REGION...ESPECIALLY THE NORTHEAST MOUNTAINS. THIS
WILL GIVE WAY ONCE AGAIN TO IMPROVING SKY CONDITIONS BY AFTERNOON
BUT POPS LOOK TO BE ON THE INCREASE AGAIN. UPPER RIDGE AXIS
WEAKENS SLIGHTLY IN RESPONSE TO APPROACHING TROUGH.
MEANWHILE...LOW LEVEL INSTABILITY AND LAPSE RATES WILL BE ON THE
INCREASE WITH CAPE VALUES OF NEAR 3000 J/KG PROJECTED LATE
TUESDAY. GIVEN FLOW PATTERN...WOULD EXPECT DEVELOPMENT OVER THE NE
MOUNTAINS FIRST AND THEN PROPAGATING SW TOWARD THE ATLANTA METRO.
HAVE GONE A CONSIDERABLE AMOUNT ABOVE GUIDANCE FOR THESE AREAS.
DEESE
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
UPPER LEVEL TROUGH APPROACHING ON WEDNESDAY AND COMBINED WITH
ASSOCIATED MOIST AND INSTABILITY WILL GIVE POTENTIAL FOR NUMEROUS
SHOWERS AND SCATTERED THUNDERSTORMS ACROSS MAINLY N GA AND MAINLY
SCATTERED SHOWERS AND STORMS FOR CENTRAL GA. A WEAK COLD FRONT GETS
INTO THE AREA LATE THURSDAY...POSSIBILITY ASSOCIATED WITH SOME UPPER
LEVEL SUPPORT...WILL GIVE THE CHANCE FOR SHOWERS AND STORMS. BEST
MOISTURE AND UPPER SUPPORT DRIFTING EAST ON FRIDAY ALLOWING FOR ONLY
A SLIGHT CHANCE OF SHOWERS AND STORMS. OVERALL MOISTURE AND
INSTABILITY APPEAR LACKING SATURDAY INTO MONDAY AND WHILE PRECIP
POTENTIAL IS NOT ZERO IT LOOKS TO BE LESS THAN 20 PERCENT AT THIS
TIME. TEMPERATURES RUNNING WITHIN 5 DEGREES OF NORMAL THROUGH THE
PERIOD.
BDL
&&
.AVIATION...
06Z UPDATE...REMAINS A CHALLENGING FORECAST WITH CIGS THE BIG
QUESTION AND UNCERTAINTY IS GREAT WITH THE GUIDANCE. WITH THE
AMOUNT OF RAIN MOST AREAS HAVE SEEN...LEANING TOWARD THE MORE
PESSIMISTIC PROJECTIONS OF IFR DEVELOPMENT AT THE TERMINALS
TONIGHT. VSBY SHOULD REMAIN MVFR AT ATL BUT AGAIN CONFIDENCE IS
LOW. BETTER CHANCE OF LOWER VSBY AND LIFR CONDITIONS AT AHN AND
MCN WHERE LOW LEVEL MOISTURE BECOMES MORE PREVALENT TOWARD
DAYBREAK. SHOULD SEE CIGS LIFT TO VFR BY LATE MORNING TO EARLY
AFTERNOON WITH DECK SCATTERING OUT BY MID AFTERNOON.
//ATL
CONFIDENCE...06Z UPDATE...
LOW ON CIGS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 65 86 64 / 20 5 40 40
ATLANTA 85 68 86 67 / 20 5 30 30
BLAIRSVILLE 82 58 83 63 / 20 5 30 30
CARTERSVILLE 86 65 87 66 / 20 5 20 20
COLUMBUS 88 67 89 67 / 20 10 20 20
GAINESVILLE 83 65 85 66 / 20 5 40 40
MACON 86 64 88 64 / 30 5 30 30
ROME 87 65 88 66 / 20 5 20 20
PEACHTREE CITY 86 62 87 63 / 20 5 30 30
VIDALIA 85 66 87 69 / 40 20 30 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
148 AM EDT MON MAY 20 2013
.PREV DISCUSSION... /ISSUED 1114 PM EDT SUN MAY 19 2013/
UPDATE...CONVECTION HAS FINALLY PUSHED SOUTH OF THE AREA BRINGING
PRECIP TO AN END AS WELL AS THE THREAT FOR ANY ADDITIONAL STRONG
OR SEVERE STORMS. HOWEVER...FLOODING CONTINUES WITH AREAL FLOOD
AND RIVER WARNINGS REPLACING FLASH FLOOD WARNINGS FROM EARLIER.
THERE COULD BE SOME ADDITIONAL RIVERS TO GO INTO FLOOD BUT NOTHING
TO WARRANT CONTINUATION OF FLOOD WATCH AND HAVE LET IT EXPIRE.
UPDATE WILL INCLUDE TRIMMING POPS FURTHER BUT REMAINING ELEMENTS
LOOK ON TRACK.
DEESE
PREV DISCUSSION... /ISSUED 750 PM EDT SUN MAY 19 2013/
PREV DISCUSSION... /ISSUED 312 PM EDT SUN MAY 19 2013/
SHORT TERM /TONIGHT THROUGH MONDAY/...
A RATHER MESSY UPPER LEVEL SYSTEM CONTINUES TO KEEP THE RISK OF
THUNDERSTORMS WITH HEAVY RAIN OVER MUCH OF THE CWA LATE THIS
AFTERNOON. REDEVELOPMENT OF THUNDERSTORMS ACROSS EASTERN TN/NORTH
GA IS REINFORCING THE FORECAST BY THE HRRR WHICH BRINGS ANOTHER
ROUND OT THUNDERSTORMS DOWN THE WEST SIDE OF GA THROUGH 00Z. THIS
WILL ALSO KEEP THE RISK OF FLASH FLOODING OVER THE WATCH AREA
THROUGH 00Z. THE PRECIP WILL SLOWLY EXIT FROM THE WEST TONIGHT
ALTHOUGH SOUTHEAST/EAST GA WILL STILL SEE SCATTERED
SHOWERS/TSTORMS INTO MONDAY. BY MONDAY AFTERNOON HIGH PRESSURE
WILL BE BUILDING OVER AL/GA WHICH SHOULD ALSO STABILIZE THE
ATMOSPHERE ENDING THE PRECIP BY MONDAY NIGHT/TUESDAY. MAV/MET
TEMPS LOOKING ALRIGHT...PERHAPS ON THE COOL SIDE TONIGHT AND HAVE
RAISE THEM A DEGREE OR TWO. WITH MORE SUNSHINE MONDAY
AFTERNOON...EXPECT TEMPS TO RISE WELL INTO THE 80S MOST AREAS.
17
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
VERY FEW CHANGES TO THE EXTENDED. MADE SOME ADJUSTMENTS TO TEMPS
ON SATURDAY TO ACCOUNT FOR DRY CAD PROGGED TO DEVELOP. 12Z RUNS OF
GFS AND ECMWF STILL SIMILAR FOR THE SYSTEM AT THE END OF THE WEEK WITH
VERY LITTLE PRECIP EXPECTED AND THE FRONT MOVING THROUGH SOMETIME
EARLY FRIDAY. ALSO INCREASED CLOUD COVER A LITTLE FOR THE
WEDNESDAY SYSTEM AND ADJUSTED TEMPS ACCORDINGLY THERE AS
WELL...OTHERWISE NO SIGNIFICANT CHANGES.
TDP
PREV DISCUSSION... /ISSUED 357 AM EDT SUN MAY 19 2013/
PRECIP SHOULD END FROM WEST TO EAST TONIGHT AS THE SHORTWAVE
TROUGH SETS UP ALONG THE EASTERN SEABOARD. HAVE ONLY TWEAKED POPS
DURING THIS PERIOD.
FOR THE FIRST PART OF THE WEEK...THE 500MB TROUGH/SHEAR AXIS REMAINS
ACROSS THE SE COAST. THIS FEATURE WILL HELP FOCUS SCT DIURNAL
CONVECTION EACH DAY. PREVIOUS RUNS PUSHED THE FEATURE OFF THE COAST
ON TUESDAY...BUT IT SHOULD REMAIN IN PLACE UNTIL EARLY WEDNESDAY.
FOR THE LATTER PART OF THE WEEK...A COLD FRONT IS EXPECTED TO MOVE
INTO THE SOUTHEAST STATES. MODEL RUN TO RUN CONSISTENCY FOR THIS
FEATURE HAS BEEN LOW FOR THE PAST FEW DAYS. THE ECMWF NOW HAS THE
BOUNDARY APPROACHING NORTHERN GA ON FRIDAY...AND MOVING THROUGH THE
CWFA DURING THE DAY. THE GFS HAS CONTINUES TO BRING THE BOUNDARY
SOUTHWARD. NEITHER MODEL IS PRODUCING MUCH PRECIP WITH THIS FEATURE
FOR NOW...SO WILL LEAVE POPS IN THE SCT RANGE.
HIGH PRESSURE RETURNS FOR NEXT WEEKEND.
MAIN CHANGES TO THE EXTENDED WERE TO UP POPS SLIGHTLY IN THE EAST
FOR WEDNESDAY. MAINLY PERSISTENCE FOR THE LATTER HALF OF WEEK.
NLISTEMAA
&&
.AVIATION...
06Z UPDATE... REMAINS A CHALLENGING FORECAST WITH CIGS THE BIG
QUESTION AND UNCERTAINTY IS GREAT WITH THE GUIDANCE. WITH THE
AMOUNT OF RAIN MOST AREAS HAVE SEEN...LEANING TOWARD THE MORE
PESSIMISTIC PROJECTIONS OF IFR DEVELOPMENT AT THE TERMINALS
TONIGHT. VSBY SHOULD REMAIN MVFR AT ATL BUT AGAIN CONFIDENCE IS
LOW. BETTER CHANCE OF LOWER VSBY AND LIFR CONDITIONS AT AHN AND
MCN WHERE LOW LEVEL MOISTURE BECOMES MORE PREVALENT TOWARD
DAYBREAK. SHOULD SEE CIGS LIFT TO VFR BY LATE MORNING TO EARLY
AFTERNOON WITH DECK SCATTERING OUT BY MID AFTERNOON.
//ATL
CONFIDENCE...06Z UPDATE...
LOW ON CIGS.
HIGH ON REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 86 65 86 67 / 10 10 30 20
ATLANTA 86 67 85 69 / 10 10 30 10
BLAIRSVILLE 83 60 82 64 / 10 10 40 20
CARTERSVILLE 87 65 87 67 / 10 10 20 20
COLUMBUS 89 67 89 71 / 10 10 10 10
GAINESVILLE 83 65 83 67 / 10 10 40 20
MACON 87 65 88 68 / 20 20 20 10
ROME 88 64 87 68 / 10 10 20 10
PEACHTREE CITY 86 65 86 66 / 10 10 20 10
VIDALIA 88 67 87 70 / 50 40 40 10
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
343 PM CDT SAT MAY 18 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 330 PM CDT SAT MAY 18 2013
MAIN CONCERNS TONIGHT WILL BE EXTENT OF CONVECTION ACROSS THE
FORECAST AREA LATE NIGHT AND INTO EARLY MORNING. MODELS SIMILAR IN
TIMING BUT VERY LITTLE AGREEMENT IN AREAL COVERAGE/PLACEMENT OF
RAINFALL OVERNIGHT SO CONFIDENCE LOW AT THIS TIME. SYNOPTIC SETUP
SHOWS APPROACHING H700 SHORTWAVE OVER PANHANDLE AREA OF TEXAS/OK
NOW AND SIMPLE TIME OF ARRIVAL TOOL SHOWS AT CURRENT SPEED WILL
ARRIVE INTO SW COUNTIES AFT 07Z AND INTO CENTRAL IOWA BY ABOUT
10Z...FAVORED TIME FOR NOCTURNAL CONVECTION. THIS CORRELATES
PRETTY WELL WITH INCREASING WIND FIELDS FROM THE GFS OVERNIGHT
WITH H850 40KT JET ENTERING AREA AND SUFFICIENT SPEED SHEAR FROM
H700/H500 OF 40-60KTS RESPECTIVELY FROM 08-12Z. SFC BOUNDARY LOOKS
TO MAKE IT AS FAR NORTH AS IA/MO BORDER BY 12Z AS WELL. MOISTURE
IS QUITE HIGH FOR THIS EVENT WITH PWATS BY 12Z APPROACHING +90-95%
LEVEL OF CLIMATOLOGICAL MAX AND NEAR 2 STANDARD DEVIATIONS FROM
NORMAL. WARM CLOUD DEPTHS LOOK FAIRLY IMPRESSIVE WITH 10-11KFT
EXPECTED LATE TONIGHT AND A GOOD SHARE OF SUNDAY AS WELL. WITH
EXPECTED SHORT WAVE AND FORECAST CONDITIONS...HAVE SOME CONCERNS
ABOUT LOCALLY HEAVY RAINFALL AND POTENTIAL FOR ISOLATED FLASH
FLOODING OVER THE WEST/SOUTHWEST AREAS SHOULD MCS HOLD TOGETHER AS
IT TRACKS NORTHEAST. CURRENT 3 HR GRIDDED FLASH FLOOD GUIDANCE OF
+2-3 INCHES REMAINS PRETTY HIGH OVER MUCH OF SOUTHERN 2 TIER
COUNTIES...BUT WEST OF I35 AND AREAS NORTH OF THERE HAVE LOWER
VALUES OF 1.75 TO 2 INCHES IN GENERAL. WITH HIGH PWATS AND
SIGNIFICANT WARM CLOUD DEPTHS COMBINED WITH SHORT WAVE WE CLOUD
SEE ISOLATED RAINFALL AMOUNTS OF 1 TO 2+ INCHES OVER THE SOUTHWEST
TO CENTRAL COUNTIES BY 12Z...WITHIN TRACK OF MCS. THE CHALLENGE
REMAINS HOWEVER...IN THAT THE 4 KM WRF AND HRRR WILL NEED TO WATCH
THIS THROUGH EVENING TO SEE HOW SITUATION EVOLVES. LOWS OVERNIGHT
WILL BE QUITE MILD AGAIN WITH INCREASING MOISTURE PUTTING A CAP ON
MINS IN THE LOWER TO MID 60S. SOME CONCERN REMAINS ABOUT POTENTIAL
FOR SEVERE OVERNIGHT...BUT IF ANY OCCURS WILL BE MAINLY FOR LARGE
HAIL OVER THE WEST.
.LONG TERM.../SUNDAY THROUGH SATURDAY/...
ISSUED AT 330 PM CDT SAT MAY 18 2013
MAIN FORECAST CONCERN REMAINS FOCUSED ON ACTIVE WEATHER PATTERN
DEVELOPING OVER THE NEXT SEVERAL DAYS. MODELS IN GOOD AGREEMENT
THROUGH EARLY IN THE WEEK WITH CUTOFF LOW LINGERING THROUGH
THURSDAY. LEANED A BLEND OF THE NAM12 AND ARW-WRF FOR TIMING AND
TRENDS TOMORROW INTO TOMORROW NIGHT...THEN A GFS/ECMWF THROUGH
MIDWEEK.
.SUNDAY INTO MONDAY...STRONG 500MB TROUGH DIGS INTO THE CENTRAL
PLAINS TONIGHT AND SLOWLY MAKE ITS WAS INTO THE MIDWEST BY TOMORROW.
FIRST SHORTWAVE THAT MAY SPAWN THUNDERSTORMS OVERNIGHT TONIGHT
LINGERS INTO NORTHERN IOWA THROUGH SUNDAY MORNING AND DIMINISH AS
THE LLJ DECREASES. DECREASED POPS ACROSS THE SOUTH CONSIDERABLY
UNTIL THE LATE AFTERNOON BEFORE REDEVELOPMENT BY THE AFTERNOON
BEFORE NEXT SHORTWAVE EJECTS ACROSS THE CENTRAL PLAINS AND INTO
MO/IA BY 00Z MONDAY.
DESTABILIZATION OCCURS LATE SUNDAY MORNING AND INTO THE AFTERNOON
AS THE 0-3KM ML CAPE INCREASES TO 800 TO NEAR 2000 J/KG OVER
CENTRAL AND SOUTHERN IOWA BY 00Z MONDAY WITH BREAK BETWEEN
SHORTWAVES. SURFACE BASED CAPE INCREASES TO OVER 2500 J/KG BY THE
SAME TIME AND LOCATION. LOW LEVEL SHEAR MORE FAVORABLE FOR
TORNADIC DEVELOPMENT ACROSS FAR SOUTHWEST IOWA WHERE 0-1KM SHEAR
INCREASE TO 20-25 KNOTS...MORE IN THE 10 TO 15 KNOTS RANGE FURTHER
NORTH. DEEP LAYER SHEAR FAVORABLE FOR LONG LIVED STORMS LATE
TOMORROW AFTERNOON INTO THE EVENING HOURS. KEPT MENTION OF SEVERE
WX FOR SOUTHERN PORTIONS OF THE FORECAST AREA SUNDAY LATE
AFTERNOON AND INTO THE EVENING. IN ADDITION TO SEVERE
POTENTIAL...HEAVY RAIN LOOKS IMMINENT AS WELL WITH WARM LAYER
CLOUD DEPTHS RANGING AROUND 11000 FEET AND PRECIPITABLE WATER
VALUES IN THE 1.5 TO 1.75 INCH RANGE. CORFIDI VECTORS INDICATING
TRAINING STORMS TOMORROW NIGHT LEADING TO FLASH FLOODING
POTENTIAL. STORMS LOOK TO PUSH INTO NORTHERN IOWA EARLY MONDAY
MORNING AND LOWERED POPS IN CENTRAL AND SOUTHERN IOWA.
.TUESDAY THROUGH SATURDAY...UPPER LOW BECOMES CUTOFF AND LINGERS
OVER THE REGION BEFORE FINALLY MOVES EAST BY THURSDAY MORNING.
SEVERE WEATHER CHANCES LOOK MINIMAL...BUT ADDITIONAL PERIODS OF RAIN
ARE LIKELY INTO THURSDAY. TEMPERATURES LOOK TO BE NEAR OR SLIGHTLY
BELOW NORMAL BY WEDNESDAY AND THROUGH LATE IN THE WEEK.
&&
.AVIATION...18/18Z
ISSUED AT 1246 PM CDT SAT MAY 18 2013
OVERNIGHT CONCERNS REGARDING CONVECTION AND OVERALL COVERAGE.
MODELS SUGGESTING MCS DEVELOPMENT NEAR/IN AREA BY 10-15Z SUNDAY
BUT PLACEMENT SOMEWHAT CHALLENGING FOR NOW. HAVE CONSIDERED WARM
AIR ADVECTION AND NOSE OF INCREASING SOUTHERLY JET WITH WARM
FRONTAL PLACEMENT...ALL POINTING TO DEVELOPMENT AFFECTING EITHER
KDSM OR KFOD GREATER THAN AREAS EAST/NORTH. THUS...FOR NOW HAVE
INCREASED LIKELIHOOD OF TSRA AT THOSE TWO SITES FOR EARLY MORNING
HOURS. WINDS WILL LIKELY REMAIN JUST UNDER 12KT OVERNIGHT WITH
INCREASING SOUTHERLY FLOW AFT 04Z. WITH OVERNIGHT CONVECTION...
BEGIN TO EXPECT THE MCS TO DIMINISH TOWARD THE END OF PERIOD AS
JET WEAKENS AFTER 12Z. NEXT ROUND OF CONVECTION MORE LIKELY LATE
AFTERNOON OR AFT 20/00Z AS SHORTWAVE APPROACHES FROM WEST.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...REV
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
146 AM EDT MON MAY 20 2013
.UPDATE...
ISSUED AT 146 AM EDT MON MAY 20 2013
MADE A FEW TWEAKS TO THE LOW TEMPERATURES BASED ON THE LATEST TRENDS
IN OBSERVATIONS...OTHERWISE THE FORECAST IS ON TRACK.
UPDATE ISSUED AT 1029 PM EDT SUN MAY 19 2013
SHOWER ACTIVITY DISSIPATED ABOUT 2 HOURS AGO WITH NO MORE ACTIVITY
EXPECTED TONIGHT DESPITE THE HI RES MODELS TRYING TO SHOW MORE
DEVELOPMENT OVERNIGHT. NO REAL TRIGGERS WITH HIGH PRESSURE BUILDING
IN...SO NO REASON TO GO WITH ANY POPS OVERNIGHT. SKIES ARE BEGINNING
TO CLEAR OFF...AND I IMAGINE SOME FOG IS ALREADY DEVELOPING IN THE
VALLEYS. LOCALLY DENSE FOG IS EXPECTED GIVEN THE CLEARING SKIES.
FORECAST IS HANDLED WELL...SO NO UPDATE PLANNED RIGHT NOW.
UPDATE ISSUED AT 740 PM EDT SUN MAY 19 2013
THINGS HAVE QUIETED DOWN FOR MUCH OF THE AREA. HOWEVER...VERY
UNSTABLE AIRMASS CONTINUES TO HOLD ITS GROUND ALONG AND NORTH OF
I-64...WITH MANY LOCATIONS STILL AROUND 80 DEGREES AT THE MOMENT.
UPDATED EARLIER TO INCLUDE A MENTION OF HAIL AND WINDS AS WE HAVE
SEEN SOME PRETTY GOOD STORMS ACROSS CENTRAL KENTUCKY AND CAN`T RULE
OUT SOME STRONG STORMS ACROSS THE NORTHERN PORTION OF THE AREA
OVER THE NEXT FEW HOURS. AFTER SUNSET...STUFF SHOULD REALLY DROP
OFF...WITH A QUIET NIGHT ANTICIPATED. STILL SOME QUESTION AS TO HOW
EXTENSIVE THE FOG WILL BE TONIGHT. WITH DEWPOINTS RUNNING WELL ABOVE
THEIR READINGS FROM YESTERDAY AT THIS TIME...IF WE CAN CLEAR OUT
TONIGHT...THE POTENTIAL FOR DENSE FOG WOULD CERTAINLY INCREASE. WILL
CONTINUE TO EVALUATE THE NEED FOR ANY STATEMENTS FOR ADVISORIES OVER
THE NEXT FEW HOURS TO SEE HOW THE CLOUDS EVOLVE OR DISSIPATE.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 310 PM EDT SUN MAY 19 2013
MID/UPPER LOW OVER NORTHEAST KY WILL CONTINUE TO PULL AWAY WITH UPPER
RIDGING BUILDING INTO THE AREA FOR MONDAY. AN UPPER LEVEL LOCAL SPEED
MAXIMUM ON THE SOUTHERN SIDE OF THE LOW HAS HELPED SUPPORT THE
DEVELOPMENT OF NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS THE
SOUTHERN PART OF THE FORECAST AREA TODAY. SPEED MAX IS FORECAST TO WEAKEN
AND MOVE AWAY FROM THE AREA. THIS COMBINED WITH LOSS OF DAYTIME
HEATING SHOULD RESULT IN A QUICK DECREASE IN CONVECTION THIS EVENING.
THIS IS SUPPORTED BY THE 12Z NAM AND LATEST HRRR. THE HRRR DOES HAVE
SOME CONVECTION LINGERING TO AT LEAST MIDNIGHT...AND WILL KEEP A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN THE SOUTHEAST THROUGH
THIS TIME. FOG WILL DEVELOP AGAIN TONIGHT...WITH LOCALLY DENSE FOG
ESPECIALLY IN AREAS WHERE RAIN FELL TODAY.
WITH UPPER RIDGING OVER THE AREA ON MONDAY EXPECT CONVECTION TO BE
LESS ORGANIZED...EVEN THOUGH LOW LEVEL LAPSE RATES AND SURFACE BASED
INSTABILITY WILL BE GREATER THAN TODAY. WHILE THERE WILL NOT BE ANY
UPPER FORCING LIKE TODAY THERE WILL BE NUMEROUS BOUNDARIES LEFT FROM
TODAYS CONVECTION...SO WILL GO WITH SLIGHT CHANCE TO CHANCE
PROBABILITIES OVER ALL BUT THE FAR WESTERN TIER OF COUNTIES FOR
MONDAY. EXPECT ANY CONVECTION ON MONDAY TO AGAIN QUICKLY DISSIPATE
DURING THE EVENING.
WITH SHORT RANGE SOIL MOISTURE AND DROUGHT INDICES
SHOWING WETTER THAN NORMAL CONDITIONS IN THE FORECAST AREA WILL
CONTINUE TO DISREGARD THE GFS MOS HIGH TEMPERATURES OF 90 DEGREES FOR
MONDAY. WILL GO MOSTLY WITH MIDDLE 80S. RECORD HIGHS FOR MONDAY ARE
85 IN 1987 AT JKL AND 88 IN 1962 AT LOZ. WILL ALSO LEAN TOWARDS THE
NAM MOS PROBABILITY OF RAIN CHANCE GUIDANCE WHICH KEEPS LOW CHANCES
FOR TONIGHT AND MONDAY NIGHT...WITH BEST CHANCE FOR MONDAY. THIS IS
THE COMPLETE OPPOSITE OF THE GFS MOS GUIDANCE WHICH PLACES LOW
PROBABILITIES ON MONDAY WITH THE BEST CHANCES TONIGHT AND MONDAY
NIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 310 PM EDT SUN MAY 19 2013
THE EXTENDED FORECAST BEGINS WITH A RIDGE OVER THE EAST COAST AND A
SERIES OF MID LEVEL DISTURBANCES PRESSING EAST ALONG THE NRN CONUS
BORDER. A WAVE IN THE ERN PLAINS HAS SOUTHERLY FLOW AT THE SFC
WHICH WILL BRING GULF MOISTURE INTO ERN KY. SCATTERED TO NUMEROUS
SHOWERS AND A FEW THUNDERSTORMS WILL OCCUR WITHOUT MUCH ORGANIZATION
AS THE SFC LOW TAKES FORM AND MOVES INTO THE WRN GREAT LAKES. BY WED
THE COLD FRONT WILL MOVE INTO WRN KY AS THE MID LEVEL OPENS INTO A
WAVE AS IT PUSHES OVER THE ERN RIDGE. WED NIGHT WILL SEE A SERIES OF
WAVES CYCLE AROUND THE SRN EDGE OF THE 50H DISTURBANCE WITH
SCATTERED AREAS OF PCPN REFLECTED AT THE SFC. BY EARLY FRI MORNING
THE UPPER PATTERN HAS CHANGED TO A PLAINS RIDGE AND COASTAL TROFS.
SFC HIGH PRESSURE WILL DROP FROM THE NRN PLAINS AND BRING A PERIOD
OF DRY WEATHER. THAT WILL LAST THRU THE WEEKEND AS THE SFC HIGH
DRIFTS TOWARD THE EAST COAST WITH THE UPPER PATTERN BECOMING MORE
PROGRESSIVE.
FOR SENSIBLE WEATHER THE SOUTHERLY FLOW FROM THE GULF ON TUE WILL
BRING SCATTERED PCPN ALONG WITH TEMPS INTO THE MID 80S. THIS PATTERN
WILL CONTINUE THRU WED WITH OVERNIGHT LOWS RESTRICTED TO THE MID 60S
DUE TO HIGH DWPTS AND CLOUDS. THEN ON THU THE FIRST COLD FRONT WILL
CROSS ERN KY WITH SCATTERED STORMS AND COOLER TEMPS AS HIGHS ONLY
REACH THE UPPER 70S AND LOWS THU NIGHT DROP TO AROUND 60. WITH THE
SECOND SURGE OF COLD AIR FOLLOWING ON FRI LOOK FOR HIGHS IN THE MID
70S AND CLEARING LATE FRI WILL ALLOW OVERNIGHT LOWS TO DROP TO THE
MID 50S. THE COOL AIR WILL KEEP SAT HIGHS IN THE LOWER 70S IN SPITE
OF A REDUCTION IN CLOUDS EARLY AS THE DAYTIME MIXING WILL HELP
INCREASE CLOUD COVER TO COMPLEMENT THE COOLER NORTH WINDS. AS THE
DRIER AIR MOVES INTO ERN KY ON SUN THE WINDS WILL DIMINISH WITH THE
HIGH PRESSURE CROSSING TO OUR NORTH AND THE SUN WILL BEGIN THE
HEATING TO PUSH HIGHS BACK INTO THE MID 70S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 146 AM EDT MON MAY 20 2013
FOG WILL AGAIN BE A CONCERN OVERNIGHT...WITH BETTER PRECIPITATION
COVERAGE FROM YESTERDAY AFTERNOON. HAVE HIT THE FOG MORE SO AT JKL
AND LOZ SINCE BOTH LOCATIONS SAW DECENT RAINFALL. THERE IS SOME
LINGERING CU...SO CONDITIONS MAY NOT DETERIORATE UNTIL THE 09 TO 12Z
RANGE. ONCE THE FOG BURNS OFF...A RETURN TO VFR IS EXPECTED TO HOLD
THROUGH THE REST OF THE PERIOD. A FEW SHOWERS OR THUNDERSTORMS WILL
BE POSSIBLE DURING PEAK HEATING...HOWEVER THESE SHOULD BE ISOLATED
ENOUGH TO LEAVE OUT THE MENTION AT THE TAF SITES.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...SBH
LONG TERM...DUSTY
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
519 AM EDT MON MAY 20 2013
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 330 AM EDT MON MAY 20 2013
A SLOW MOVING LOW PRESSURE SYSTEM WILL BRING SHOWERS AND
THUNDERSTORMS TO SOUTHERN LOWER MICHIGAN TODAY THROUGH WEDNESDAY. A
FEW STRONG TO SEVERE STORMS ARE POSSIBLE DAILY. COOLER AIR WILL MOVE
IN LATE THIS WEEK.
&&
.UPDATE...
ISSUED AT 518 AM EDT MON MAY 20 2013
A FEW SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO DEVELOP ON
THE WARM FRONT FROM BIG SABLE POINT TO NORTHEAST KENT COUNTY AS OF
515 AM THIS MORNING. THE STORMS ARE MOVING NORTHEAST AROUND 40 MPH.
WHILE RAP SOUNDINGS DO SHOW OVER AROUND 100 J/KG OF CIN THERE IS
NEARLY 1000 J/KG OF CAPE ONCE THE CIN IS OVERCOME. I EXPECT THE
STORMS TO CONTINUE TO LIFT NORTH AND EAST OUT OF THE CWA BY 9 AM
THIS MORNING. BASED ON THIS I UPDATED THE GRIDS AND ZONES TO
INDICATE POSSIBLE THUNDERSTORMS FROM I-96 NORTH INTO MID MORNING.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY AFTERNOON)
ISSUED AT 330 AM EDT MON MAY 20 2013
PRIMARY SHORT TERM FCST CONCERNS INVOLVE EVALUATION OF
CONVECTIVE/SVR WX POTENTIAL TODAY THROUGH WEDNESDAY.
A WARM FRONT LIFTING NORTH ACROSS OUR AREA LATER TODAY AND
INCREASING INSTABILITY WILL LEAD TO THE DEVELOPMENT OF SHOWERS AND
STORMS. SOME STRONG TO SEVERE STORMS ARE POSSIBLE PARTICULARLY THIS
AFTERNOON AND EVENING AS SB CAPE VALUES POTENTIALLY REACH AROUND
2000-3000 J/KG NEAR TO SOUTH OF I-96 ALONG WITH STRONGLY NEGATIVE
LI/S AND TOTAL TOTALS INDICES INTO THE MID TO UPPER 50S.
SOME 00Z GUIDANCE FCST SOUNDINGS HAVE AN INVERTED V LOOK BY LATER
THIS AFTN/EVENING SO THERE IS POTENTIAL FOR STRONG TO SEVERE STORMS
TO PRODUCE DAMAGING WIND GUSTS. IN ADDITION LARGE HAIL IS ALSO
POSSIBLE BOTH WITH SFC BASED STORMS AND WITH ELEVATED CONVECTION
NORTH OF THE WARM FRONT. CANNOT RULE OUT AN ISOLATED TORNADO NEAR TO
SOUTH OF THE WARM FRONT THIS AFTERNOON AND EVENING ALTHOUGH THIS
POTENTIAL IS MITIGATED SOMEWHAT BY FAIRLY HIGH LCL HEIGHTS.
SCATTERED STRONG TO POTENTIALLY SVR STORMS ARE POSSIBLE AGAIN
TUESDAY ALTHOUGH WE STILL FEEL THAT POTENTIAL TOMORROW IS NOT AS
GREAT AS LATER TODAY WITH A CONSENSUS OF LATEST 00Z GUIDANCE SHOWING
LESS INSTABILITY/MUCH MORE CLOUD COVER AROUND. THE SVR WX THREAT
TUESDAY WILL BE LARGELY CONTINGENT ON HOW CONVECTIVE EVOLUTION
OCCURS TONIGHT AND ON EXTENT ON CLOUD COVER.
THE SEVERE WX THREAT CONTINUES WEDNESDAY AS THE SFC LOW FINALLY
MOVES EAST INTO MICHIGAN AND AS THE UPPER LEVEL SUPPORT/UPPER TROF
AND ASSOCIATED COLD POOL OF AIR ALOFT MOVE IN. THE 12Z ECMWF/00Z GFS
IN PARTICULAR SUGGEST DECENT SVR WX POTENTIAL WEDNESDAY GIVEN THE
TIMING OF THE SFC LOW AND FRONTAL POSITIONS THROUGH OUR REGION. ALL
THINGS CONSIDERED AT THIS TIME WE BELIEVE THE BEST CHC FOR ORGANIZED
SVR WX WILL BE WEDNESDAY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON MAY 20 2013
THE RAIN SHOWERS SHOULD COME TO AN END BY LATE IN THE DAY THURSDAY.
BY THEN THE THREAT FOR THUNDERSTORMS WILL BE SOUTH OF MICHIGAN. A
CANADIAN HIGH WILL MOVE IN FOR THE FRIDAY INTO SATURDAY TIME FRAME.
THIS BRINGS CANADIAN POLAR AIR SOUTH WITH IT SO THERE IS A THE
THREAT OF FROST OVER THE NORTHERN TWO ROWS OF COUNTIES EARLY
SATURDAY MORNING. ANOTHER PACIFIC STORM WILL LIKELY TO TRACK SOUTH
OF THE AREA BUT WILL BRING THE TREAT OF A LIGHT RAIN SHOWERS SUNDAY.
CONFIDENCE IN THIS FORECAST IS ABOUT AVERAGE. THE MODELS ALL AGREE
ON THE OVERALL PATTERN INTO NEXT WEEK. THERE ARE MINOR ISSUES IN THE
DETAILS BUT LITTLE QUESTION THE SYSTEM OVER US NOW WILL BE SHEARED
OUT TO THE EAST BY FRIDAY MORNING. THE LONGWAVE RIDGE WILL SURELY
BUILD TO OUR WEST BEHIND THE DEPARTING SYSTEM. THAT WILL BRING IN
COOLER AIR FRIDAY INTO SATURDAY. THE UPPER RIDGE TO OUR WEST WILL
THEN SLOWLY BUILD EAST OVER TIME PUSHING THE COLD AIR OUT ONCE AGAIN
(EARLY NEXT WEEK). THERE IS SOME QUESTION AS TO WHAT HAPPENS THE
SOME OF THAT PACIFIC SHORTWAVE ENERGY OVER THE WEEKEND AS THE WARM
AIR PUSHES TOWARD US. THE ECMWF KEEPS THE PRECIPITATION SOUTH OF
MICHIGAN THROUGH THE WEEKEND AND THE GFS BRINGS IT IN SUNDAY. I HAVE
LOW CHANCE POPS FOR THAT BUT I AM CURRENTLY THINKING THIS WILL
ACTUALLY MISS US TO THE SOUTH JUST LIKE THE ECMWF SUGGEST.
THE RAIN ON THURSDAY IS DEFORMATION ZONE RELATED AS THE SYSTEM
SHEARS OUT TO THE EAST BUT THERE IS LITTLE OF ANY INSTABILITY WITH
THIS... JUST SHOWERS. THE CONVECTIVE THREAT IS LARGELY OVER BY MID
EVENING WEDNESDAY.
AS FOR THE FROST THREAT... WITH THE CANADIAN HIGH BUILDING IN FRIDAY
INTO SATURDAY... WINDS WILL BECOME LIGHT AND VARIABLE EARLY SATURDAY
MORNING AND SKIES WILL BE CLEAR. DEW POINTS LIKELY WILL FALL INTO
THE LOWER TO MID 30S SO A GOOD SET UP FOR FROST OVER THE NORTHEAST
COUNTIES. AREAS SOUTH OF ROUTE 10 SHOULD STAY WARM ENOUGH FOR THIS
NOT TO BE AN ISSUE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1208 AM EDT MON MAY 20 2013
EXPECT VFR CONDITIONS THROUGH MUCH OF THE NIGHT. THERE IS STILL A
CHANCE OF SOME SHOWERS WITH MVFR CONDITIONS AFTER MIDNIGHT...BUT
THIS MAY BE IN THE FORM OF DISSIPATING SHOWERS AND SO COVERAGE MAY
BE SPARSE UNTIL MORE MOISTURE ARRIVES LATER ON MONDAY AFTERNOON.
THE COVERAGE AND TIMING OF THUNDERSTORMS ON MONDAY AFTERNOON IS
HARD TO PIN DOWN BUT MVFR AND LOCAL IFR IS POSSIBLE AFTER 18Z
MONDAY.
&&
.MARINE...
ISSUED AT 330 AM EDT MON MAY 20 2013
MINIMAL WAVE ACTION IS EXPECTED EARLY THIS WEEK BUT THUNDERSTORMS
WILL POSE A HAZARD TO MARINERS TODAY THROUGH WEDNESDAY. FOG IS ALSO
A POTENTIAL HAZARD EARLY THIS WEEK AS A MUCH MORE HUMID AIRMASS
OVERRUNS COLD LAKE WATERS.
&&
.FIRE WEATHER...
ISSUED AT 330 AM EDT MON MAY 20 2013
WARM AND FAIRLY HUMID WEATHER IS EXPECTED TODAY THROUGH WEDNESDAY.
THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES TODAY
THROUGH WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT MON MAY 20 2013
SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED TODAY THROUGH
WEDNESDAY BUT SIGNIFICANT FLOODING IS NOT ANTICIPATED SINCE
CUMULATIVE RAINFALL AMOUNTS ON AVERAGE OF ONLY AROUND AN INCH OR TWO
ARE ANTICIPATED THROUGH WEDNESDAY NIGHT. HOWEVER LOCALIZED FLOODING
ISSUES MAY OCCUR WITH HEAVIEST STORMS OR WHERE STORMS TRACK ACROSS
THE SAME LOCATION.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...WDM
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...OSTUNO
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS GLASGOW MT
402 AM MDT MON MAY 20 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH WEDNESDAY...
TODAY AND TONIGHT...A VERTICALLY STACKED LOW PRESSURE SYSTEM
SITUATED OVER THE DAKOTAS WILL CONTINUE TO SIT AND SPIN. AS IT
DOES...A SHIELD OF STRATIFORM RAIN WILL CONTINUE TO RETROGRADE
FROM EAST TO WEST THOUGH THE DAY...BEFORE CRASHING BACK TO THE
SOUTHEAST THIS AFTERNOON AND EVENING AS THE LOW BEGINS TO
TRANSLATE EASTWARD. DETERMINING THE MAXIMUM EXTENT OF THE BACK
EDGE OF THE RAINFALL SHIELD WILL CONTINUE TO BE THE MAIN FORECAST
CHALLENGE.
THE LATEST NAM HAD THE PRECIPITATION INITIALIZED A BIT FURTHER TO
THE EAST THAN RADAR OBSERVATIONS SHOWED. THUS...FEEL THE
PRECIPITATION SHIELD SHOULD MAKE IT A BIT FURTHER THAN THIS
SOLUTION IS SUGGESTING. THE 00Z ECMWF AND GFS HAVE A LITTLE BETTER
HANDLE ON IT. WILL ADMIT THAT THE HRRR HAS BEEN AN IMPRESSIVE
INFORMER AS IT CAUGHT ONTO THE IDEA THAT THE SHIELD WOULD STOP
RETROGRADING FOR A FEW HOURS OVERNIGHT BEFORE AGAIN PROCEEDING ITS
MARCH FURTHER WEST TOWARD MORNING AND THIS IS WHAT IS OCCURRING.
LENDING FURTHER SUPPORT TO THE GUIDANCE IS THE OBSERVATION OF
RECENT PRESSURE FALLS ACROSS THE CWA. PRESSURES ARE GENERALLY
FALLING BETWEEN 0.5 AND 1 MB PER HOUR FOR THE LAST FEW HOURS.
THEREFORE...WILL FEEL COMFORTABLE WITH A BLEND OF THE
ECMWF/GFS/HRRR MODEL SOLUTIONS FOR DETERMINING A BEST GUESS AS TO
WHERE THE BACK EDGE WILL REACH BEFORE IT BEGINS TO PUSH BACK TO
THE SOUTHEAST. THIS BRINGS IT TO A LINE FROM ABOUT OPHEIM...EXTENDING
SOUTH THROUGH JUST WEST OF GLASGOW...TO THE JORDAN AREA. TO THE
EAST OF THIS LINE...THERE IS A DECENT CHANCE AT A NICE WETTING
RAIN THROUGH TONIGHT. IN FACT...WOULD NOT BE SURPRISED IF SOME
AREAS SEE ONE TO TWO INCHES OF RAINFALL ACCUMULATION BY THE END OF
TONIGHT AND INCLUDED A MENTION OF HEAVY RAIN IN SOME OF THE
EASTERN ZONES THROUGH THE MORNING. TO THE WEST OF THIS LINE...RAIN
CHANCES WILL ONLY BE SHOWERY IN NATURE WITH A FEW HUNDREDTHS OF AN
INCH OF ACCUMULATION THE ABSOLUTE MOST THAT WOULD OCCUR. PRECISE
RAINFALL AMOUNTS WILL DEPEND UPON THE PRECISE LOCATION OF WHERE
THE BACK EDGE OF THIS RAIN SHIELD WINDS UP...AS WELL AS SOME FINER
MESOSCALE DETAILS THAT ARE DIFFICULT TO DETERMINE WITH MUCH
CONFIDENCE. TEMPERATURES ARE KEPT AROUND OR JUST BELOW SEASONAL
NORMALS DUE TO THE PRESENCE OF THE LINGERING UPPER TROUGH.
THE OTHER CONCERN TODAY WILL BE STRONG GUSTY WINDS DUE TO A SHARP
PRESSURE GRADIENT IN ASSOCIATION WITH THE SURFACE LOW ACROSS THE
DAKOTAS. AM EXPECTING THAT THE TIGHT PACKING OF THE ISOBARS COULD
SUPPORT NORTHERLY WINDS ON THE ORDER OF 20 TO 30 MPH WITH SOME
GUSTS EXCEEDING 40 MPH THIS AFTERNOON AND EVENING. WILL HOIST A
LAKE WIND ADVISORY FROM NOON UNTIL 9PM DUE TO THIS CONCERN. THIS
MAY ALSO LEAD TO WIND DRIVEN RAINS IN SOME LOCATIONS WHICH COULD
POSE AS HAZARDS TO TRAVELERS AND PEDESTRIANS ALIKE.
TONIGHT THROUGH WEDNESDAY...THE LOW PRESSURE SYSTEM OVER THE
DAKOTAS VERY GRADUALLY TRANSLATES EASTWARD...SO CONTINUED TO TREND
POPS DOWN AND HAVE PRECIPITATION SHUTTING OFF FROM WEST TO EAST.
WILL LEAVE ONLY A SLIGHT CHANCE OF RAIN SHOWERS IN THE EXTREME SE
ZONES BY LATE TUESDAY NIGHT. ON WEDNESDAY...ANOTHER UPPER TROUGH
WITH CLOSED LOW MOVES INTO THE PACIFIC NORTHWEST AS IT DOES
SO...DIFFLUENT SOUTHWEST FLOW ALOFT IS EXPECTED TO DEVELOP ACROSS
THE CWA. THIS MAY LEAD TO CONVECTIVE SHOWERS ON WEDNESDAY...MAINLY
ACROSS THE SW ZONES. SOME OF THE SOUNDINGS IN THE NAM BUFKIT JUST
WEST OF THE CWA ARE SHOWING TOTAL TOTALS APPROACHING 50 AND LI
BECOMING NEGATIVE. DID NOT INSERT A MENTION OF THUNDER JUST YET DUE TO THE
FACT THAT THE PRIMARY FOCUS WAS ON THE CURRENT RAINFALL SITUATION
AND LAKE WIND POTENTIAL. HOWEVER...FUTURE SHIFTS MAY WANT TO
EVALUATE THE POTENTIAL FOR ANY CONVECTIVE INITIATION TOWARD THE
MIDDLE OF THE WEEK. MALIAWCO
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
THE EXTENDED FEATURES MORE SOUTHWEST FLOW THROUGH THE PERIOD. MOST
DAYS SLIGHT CHANCES OF THUNDERSTORMS SLIDING OFF THE CENTRAL
MONTANA MOUNTAINS INTO THE PLAINS FOR HIGHER POPS WEST AND LOW
POPS EAST. FOR THE WEEKEND THE UPPER LOW BREAKS A GOOD WAVE OFF
AND DRIVES IT THROUGH NORTHEAST MONTANA FOR A BETTER CHANCE OF
THUNDERSTORMS THEREFORE BUMPED UP POPS A TAD FOR THOSE PERIODS.
TEMPERATURES WILL HOLD IN NEAR NORMAL THROUGH THE PERIOD.
MODEL TRENDS ARE SHOWING LOWERING HEIGHTS ON THE GFS FOR NORTHEAST
MONTANA WHICH LEADS TO THE UPPER LOW MOVING TOWARDS THE EAST. IF
THE TREND CONTINUES THEN LIKELY POPS ARE A GOOD BET FOR THE
WEEKEND WITH ELEVATED CONFIDENCE. RMOP/ENSEMBLES ARE SHOWING THAT
ITS A GOOD BET THAT AT SOME POINT THIS UPCOMING WEEKEND FOR A
STRONG THUNDERSTORM EVENT ACROSS EASTERN MONTANA. PROTON
&&
.AVIATION...
MVFR FOR THE EASTERN AREAS INCLUDING KSDY AND KGDV THROUGH THE
PERIOD AS THEY ARE CLOSER TO THE LOW OVER SOUTHEASTERN NORTH
DAKOTA WHICH IS WRAPPING AROUND MOISTURE INTO THE LOWER YELLOWSTONE
RIVER VALLEY. THIS TREND LOOKS TO CONTINUE THROUGH THE PERIOD.
VFR FOR WESTERN AREAS INCLUDING KGGW AND KOLF THROUGH THE PERIOD
AS THE MVFR CEILING SHIELD LOOKS TO STAY JUST OFF TO THE EAST. FOR
NOW WILL STAY WITH VFR CEILINGS.
WIND WILL BE MORE OF AN ISSUE FOR THE EASTERN SITES WITH THE WINDS
STAYING UP ABOVE 20 KNOTS THROUGH THE END OF THE TAF PERIOD. PROTON
&&
.HYDROLOGY...
THE NEXT COUPLE OF DAYS WILL CONTINUE TO BE VERY WET AS NORTHEAST
MONTANA REMAINS UNDER THE INFLUENCE OF A LARGE UPPER TROUGH AND
VERTICALLY STACKED LOW PRESSURE SYSTEM SITUATED ACROSS THE
DAKOTAS. A LARGE AREA OF STRATIFORM RAIN WILL AFFECT ESPECIALLY EASTERN
AREAS OF THE FORECAST AREA. SOME LOCATIONS COULD PICK UP BETWEEN
ONE AND TWO INCHES OF RAINFALL BY TUESDAY MORNING...ESPECIALLY IN
EASTERN ROOSEVELT AND RICHLAND COUNTIES WHERE THE STEADIEST RAIN
IS EXPECTED.
MOST OF THE BASINS IN NORTHEAST MONTANA WILL BE ABLE TO
ACCOMMODATE THIS AMOUNT OF MOISTURE. HOWEVER THERE IS SOME
CONCERN FOR RAPIDLY RISING STREAMS...FIELD FLOODING AND LOCALIZED
FLOODING IN TOWNS AS THE EVENT PERSISTS. SOME MINOR FLOODING MAY
BECOME AN ISSUE...ESPECIALLY FOR THE AREAS FROM WOLF POINT TO
CIRCLE AND EASTWARD INTO NORTH DAKOTA WHERE THE POTENTIAL FOR RAIN
IS THE HIGHEST.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TODAY TO 9 PM MDT THIS EVENING FOR
CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...
GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
328 AM CDT MON MAY 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CDT MON MAY 20 2013
TODAY AND TONIGHT...
THE BAND OF SHOWERS AND RAIN ACROSS THE SOUTHWESTERN AND NORTHEAST
PORTIONS OF THE FCST AREA SHOULD EXIT SOUTH AND EAST BY
DAYLIGHT...MID MORNING AT THE LATEST. THE RAP...HRRR AND NAM THEN
DROP A SECOND BATCH OF RAIN AND SHOWERS SOUTH OUT OF WRN SD THIS
MORNING AND THIS AFTN. THIS AREA OF RAIN SHOULD PRESUMABLY CONTINUE
MOVING SOUTH THIS EVENING WITH A WEAKENING TREND.
THUNDERSTORM CHANCES ARE VERY LOW IF THE RAP AND NAM ARE CORRECT.
NEITHER INDICATE ANY ELEVATED INSTABILITY FROM 750 MB ON UP AND THE
SFC BASED NAM THUNDERSTORM PROBABILITY CHART IS 10 PERCENT OR LESS.
WINDS INCREASE TO WIND ADVISORY CRITERIA TODAY ACROSS PARTS OF THE
WEST WITH H850 WINDS INCREASING TO 45 KT. THE MET AND MAV GUIDANCE
WERE THE BASIS FOR THE FORECAST WIND SPEEDS WHICH INCREASE TO AROUND
30 MPH. WINDS SHOULD SLACKEN THIS EVENING AS LOW PRESSURE ACROSS THE
NRN PLAINS BEGINS TO FILL.
TEMPERATURES ARE A BLEND OF NAM...GEMREG AND ECM PLUS BIAS
CORRECTION FOR HIGHS AND THE 50S AND 60S TODAY WITH LOWS IN THE 40S
AND 50S TONIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 326 AM CDT MON MAY 20 2013
ON TUESDAY...
THE UPPER LOW IS FORECAST TO MOVE FROM CENTRAL INTO FAR SOUTHEAST
SOUTH DAKOTA. A LOBE ON THE WESTERN PERIPHERY OF THE LOW WILL
ROTATE THROUGH WESTERN NEBRASKA WITH A CHANCE FOR SHOWERS MAINLY
ACROSS NORTH CENTRAL NEBRASKA. DESPITE A MOIST PROFILE...LIFT WILL
BE VERY WEAK...MAINLY IN THE H850-H7 LAYER. HAVE LOWERED POPS TO
NEAR 50 PERCENT FOR SHERIDAN AND WRN CHERRY AND FROM 30-40 PERCENT
ACROSS THE REMAINDER OF NCTRL WITH SLIGHT CHANCE POPS IN SWRN NEBR
IN THE MORNING. REGARDING WINDS...STRONGEST WINDS FORECAST FROM
THE EASTERN PANHANDLE INTO SOUTHWEST NEBR...WHERE SUSTAINED WIND
WILL REACH NEAR 25KT AND GUST NEAR 35KT THROUGH THE DAY. THIS IS
DUE TO DEEP MIX DOWN POTENTIAL WHERE UNIDIRECTIONAL NORTHWEST
WINDS EXTEND FROM THE SFC TO ABOVE 400 MB. THEREFORE A WIND
ADVISORY MAY BE NEEDED IF FORECAST WINDS CONTINUE TO LOOK SIMILAR.
HIGHS WILL BE AFFECTED MOST BY CLOUD COVER/SHOWERS FROM 55-60
NCTRL TO NEAR 70 FAR SW.
TUESDAY NIGHT AND WEDNESDAY...
AS UPPER LOW MOVES SLOWLY EAST ACROSS NRN IOWA...STILL SUPPORTIVE
OF A FEW SHOWERS TUES NIGHT NORTH CENTRAL AND NORTHEAST WEDNESDAY
AS WRAPAROUND MOISTURE STILL PRESENT. AN UPPER RIDGE WILL ALSO
BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. CLEARING SKIES IN
THE WEST AND WEAK HIGH PRESSURE BUILDING IN TO BRING COOLER LOWS
FROM THE UPPER 30S TO LOWER 40S WEST TO NEAR 45 EAST. ONLY A MINOR
CHANGE TO HIGHS WEDNESDAY FROM 62-66 NCTRL TO 67-73 SOUTH.
THURSDAY THROUGH SUNDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. THE PRESENCE
OF A NOCTURNAL LOW LEVEL JET WILL ALSO ALLOW FOR THUNDERSTORMS TO
POSSIBLY DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS
FROM THE UPPER 60S TO LOWER 70S THU-FRI WILL WARM TO THE UPPER 70S
TO LOWER 80S SAT-SUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1222 AM CDT MON MAY 20 2013
A FRONT PUSHING THROUGH NEBRASKA TONIGHT WILL EVENTUALLY PUSH
SHOWERS AND THUNDERSTORMS OUT OF CENTRAL AND WESTERN NEBRASKA.
STORMS ARE EXPECTED TO CLEAR ONL-BBW-LBF BY 11Z.
AFTER 15Z...RAIN IS LIKELY TO DIP INTO NORTH CENTRAL NEBRASKA TO
NEAR MHN...TIF AND ONL AS A STORM SYSTEM MAKES ITS WAY ACROSS THE
NORTHERN PLAINS. ISOLATED THUNDERSTORMS COULD BE EMBEDDED IN THE
RAIN AREA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM THIS MORNING TO 6 PM MDT THIS EVENING
FOR NEZ004-022-023-035-056>058.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
202 AM CDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 335 PM CDT SUN MAY 19 2013
AT H5 CLOSED LOW OVER THE NORTHERN PLAINS WITH DEEP TROUGH OVER THE
WESTERN CONUS. H5 RIDGE INTO THE GREAT LAKES. H5 WAVE UNDERNEATH
RIDGE OVER THE SOUTHEAST WITH ASSOCIATED SHOWERS.
&&
.UPDATE...
ISSUED AT 154 AM CDT MON MAY 20 2013
A WIND ADVISORY IS IN PLACE ACROSS PARTS OF WESTERN NEBRASKA
TODAY. THE RAP AND OTHER MODELS SHOW H850 MB WINDS INCREASING TO
AROUND 45 KT AND THE MET AND MAV GUIDANCE HAVE BEEN FOLLOWED FOR
THIS ADVISORY. THIS IN LINE WITH KUDX VAD WIND PROFILER SHOWING 40
TO 50 KT AT 07Z. MERRIMAN PROFILER IS OUT OF SERVICE.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 335 PM CDT SUN MAY 19 2013
LARGE UPPER LEVEL LOW WILL TRACK FROM NEBRASKA TONIGHT TO SOUTH
DAKOTA MONDAY. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED TONIGHT...WITH SHOWERY WEATHER TO CONTINUE ACROSS NORTHERN
NEBRASKA MONDAY. A SEVERE STORM OR TWO CANNOT BE RULED OUT ACROSS
CENTRAL INTO EASTERN PORTIONS OF NORTH CENTRAL NEBRASKA THIS
EVENING...WHERE STRONGER FLOW ALOFT RESIDES. H85 WIND SPEEDS
INCREASE CONSIDERABLE ON THE SOUTH SIDE OF THE UPPER LEVEL LOW
MONDAY...WITH SPEEDS AT THE SFC NEARING ADVISORY CRITERIA ACROSS FAR
WESTERN NEBRASKA AND THE PANHANDLE.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 335 PM CDT SUN MAY 19 2013
MODELS IN GOOD AGREEMENT WITH SLOW EXIT OF UPPER LOW FROM THE
NORTHERN PLAINS. RAINSHOWERS WILL AFFECT NORTHERN PORTIONS OF
WESTERN NEBRASKA THROUGH WEDNESDAY. TEMPERATURES WILL BE SOME WHAT
COOLER WITH CLOUD COVER AND SCATTERED RAIN SHOWER. HYDROLOGY WILL
CONTINUE TO BE A CONCERN AND WILL HAVE TO WATCHED. LOWS IN THE 40S
AND HIGHS IN THE 60S NORTH TO LOW 70S SOUTHWEST. SHARP RIDGE
DEVELOPS OVER NORTHERN PLAINS WEDNESDAY THROUGH THURSDAY AS NEXT
SYSTEM DROPS SOUTHEAST OUT OF THE PACIFIC NORTHWEST. SOUTHWEST
FLOW AND DIVERGENCE ALOFT WITH GULF MOISTURE AVAILABLE EXPECT
THUNDERSTORM DEVELOPMENT THURSDAY NIGHT THROUGH SUNDAY MAINLY LATE
AFTERNOON AND EARLY EVENING. TEMPERATURES RISING INTO THE 70S AND
80S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1222 AM CDT MON MAY 20 2013
A FRONT PUSHING THROUGH NEBRASKA TONIGHT WILL EVENTUALLY PUSH
SHOWERS AND THUNDERSTORMS OUT OF CENTRAL AND WESTERN NEBRASKA.
STORMS ARE EXPECTED TO CLEAR ONL-BBW-LBF BY 11Z.
AFTER 15Z...RAIN IS LIKELY TO DIP INTO NORTH CENTRAL NEBRASKA TO
NEAR MHN...TIF AND ONL AS A STORM SYSTEM MAKES ITS WAY ACROSS THE
NORTHERN PLAINS. ISOLATED THUNDERSTORMS COULD BE EMBEDDED IN THE
RAIN AREA.
&&
.HYDROLOGY...
ISSUED AT 335 PM CDT SUN MAY 19 2013
ISSUED SMALL STREAM FLOOD ADVISORY FOR KEITH AND SOUTHERN GARDEN
COUNTIES AS UPPER LOW KEEPS A NARROW BAND OF RAIN OVER THE
COUNTIES WITH ALREADY SATURATED GROUND FROM THUNDERSTORMS LAST
NIGHT. THE UPPER LOW IS PULLING SLOWLY EAST. SECONDARY ROADS ARE
MUDDY AND SOME HAVE WATER CROSSING THE ROAD.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM THIS MORNING TO 6 PM MDT THIS EVENING
FOR NEZ004-022-023-035-056>058.
&&
$$
UPDATE...CDC
SYNOPSIS...POWER
SHORT TERM...TAYLOR
LONG TERM...POWER
AVIATION...CDC
HYDROLOGY...POWER
AREA FORECAST DISCUSSION
NWS RALEIGH NC
257 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON TUESDAY
REDUCING THE THREAT OF LOCALLY HEAVY RAIN.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 230 AM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
THE SLOW MOVING... ALMOST STUCK MID/UPPER LEVEL TROUGH... LOCATED
OVER WESTERN NC/SC IS EXPECTED TO ONLY SLOWLY BUDGE EASTWARD TODAY
AND TONIGHT. THIS IS A BIT SLOWER THAN HAD BEEN ADVERTISED BY
PREVIOUS MODELS... AND PUTS MUCH OF CENTRAL NORTH CAROLINA IN THE
REGION OF A LOCALLY HEAVY RAIN THREAT TODAY INTO TONIGHT. THE LATEST
MODEL FORECASTS INCLUDING THE HI-RES HRRR GUIDANCE WERE DEPICTING
MUCH OF THE EASTERN PIEDMONT... SANDHILLS AND PORTIONS OF THE
COASTAL PLAIN IN A REGION OF SIGNIFICANT LIFT OUT AHEAD OF THE TROUGH
THROUGH TONIGHT. THE HI-RES HRRR HAD A DECENT HANDLE ON THE CURRENT
AREAS OF SHOWERS. WE WILL GENERALLY FOLLOW THE FORECAST OUTPUT OF
CONVECTION THROUGH THE NEXT 6 HOURS... OR UNTIL SURFACE HEATING
TAKES OVER. THE AREA OF SHOWERS OVER THE SOUTHERN PIEDMONT
AND SANDHILLS SHOULD MOVE SLOWLY NNE INTO THE FAYETTEVILLE AND
RALEIGH AREAS THROUGH DAYBREAK... THEN WEAKEN OUT OVER THE
CENTRAL/NORTHERN COASTAL PLAIN THEREAFTER.
CONVECTION SHOULD AGAIN BLOSSOM THIS AFTERNOON WITH DIFFERENTIAL
HEATING WITH BREAKS IN THE CLOUDS AIDED BY THE SLUG OF COLDER AIR
ALOFT INCREASING LOW LEVEL INSTABILITY. THE INCREASINGLY WEAK
STEERING FLOW SHOULD ALLOW FOR SLOWER MOVING CONVECTION THIS
AFTERNOON AND EVENING... THAN OBSERVED SUNDAY. IN ADDITION... THE
PROLONGED SE FLOW FROM OFF THE GULF STREAM AND WESTERN ATLANTIC WILL
INCREASE DEW POINTS TO NEAR 70 THIS AFTERNOON. THIS POOLING OF DEEP
MOISTURE WITH PRECIPITABLE WATER VALUE FORECASTS ON THE ORDER OF
1.75 INCHES OVER THE EASTERN PIEDMONT AND WESTERN COASTAL PLAIN
SUGGEST A HEAVY RAIN THREAT. THE LACK OF A SIGNIFICANT LOW LEVEL
BOUNDARY AT THE CURRENT TIME SUGGESTS FLOODING WOULD PROBABLY BE
MORE LOCALIZED. THE HAZARDOUS WEATHER OUTLOOK WILL CONTINUE TO
HIGHLIGHT MAINLY URBAN AND SMALL STREAM FLOODING POTENTIAL WITH THE
LOCALLY HEAVY RAIN. HIGHS TODAY SHOULD INCH A BIT HIGHER THAN SUNDAY
WITH A FEW MORE BREAKS IN THE CLOUDS IN THE MORNING. HIGHS GENERALLY
78 TO 83.
SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 250 AM MONDAY...
A CONTINUED WEAKENING TREND WITH THE TROUGH AND A GRADUAL SHIFT
EASTWARD WILL MEAN MORE SCATTERED AND LESS CONCENTRATED CONVECTIVE
RAINFALL ON TUESDAY AFTERNOON AND EVENING. SEVERAL MODEL SOLUTIONS
INDICATE THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM THE WESTERN
ATLANTIC OVER PORTIONS OF NC. AFTER A START TO THE DAY WITH LOW
STRATUS AND AREAS OF FOG... PARTLY SUNNY SKIES ARE EXPECTED. HIGHS
SHOULD REBOUND INTO THE LOWER TO MID 80S. HOWEVER... DEW POINTS WILL
STILL BE IN THE MID TO UPPER 60S. THE COOLER MET/NAM GUIDANCE LOOKS
MORE IN LINE WITH THE CURRENT EXPECTATIONS WITH THE SSW FLOW AND
PLENTY OF LOW LEVEL MOISTURE AND BROKEN AFTERNOON CLOUDINESS. WIDELY
SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED. THIS
ACTIVITY WILL DIMINISH TUESDAY EVENING WITH LOSS OF HEATING. PARTLY
CLOUDY SKIES WITH AREAS OF FOG AGAIN EXPECTED LATE AT NIGHT. LOWS IN
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 AM MONDAY...
UPPER LEVEL RIDGE BUILDS BRIEFLY OVER THE AREA ON WEDNESDAY... WHICH
SHOULD DIMINISH THE COVERAGE OF CONVECTION... ALTHOUGH DIURNALLY
DRIVEN THUNDERSTORMS CONTINUE TO BE POSSIBLE WITH THE MOIST AIRMASS
OVER THE AREA. PWATS WILL REMAIN NEAR 1.5... 2 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR. WITH WEAK SHEAR... EXPECTING
PULSE TYPE STORMS. HIGHS IN THE MID 80S... LOWS MID 60S.
UPPER LEVEL RIDGE SHIFTS OFFSHORE THURSDAY. AFTERNOON THUNDERSTORMS
CONTINUE TO BE POSSIBLE IN THE AFTERNOON THURSDAY AS PWATS REMAIN
ABOVE NORMAL. BULK SHEAR INCREASES TO 25 TO 30 KTS... WHICH MAY
SUPPORT SOME MULTICELL ORGANIZATION. THICKNESSES REMAIN NEAR TO
SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY... FAVORING TEMPERATURES
CONTINUING TO A BE A FEW DEGREES ABOVE NORMAL... WITH HIGHS IN THE
80S AND LOWS IN THE UPPER 60S. THE TROUGH OVER THE MIDWEST MOVES
EASTWARD ON THURSDAY... AND THE ATTENDANT COLD FRONT PUSHES ACROSS
THE REGION FRIDAY. TIMING HAS TRENDED FASTER DURING TODAYS MODEL
RUNS... WITH THE FRONT MAKING IT THROUGH THE AREA EARLY FRIDAY...
AND TO THE CAROLINA COAST FRIDAY MORNING. STRONGEST DYNAMIC FORCING
REMAINS NORTH OVER NEW ENGLAND... AND WITH THE TIMING NOW LOOKING
MORE DIURNALLY UNFAVORABLE... DO NOT EXPECT A THREAT OF SEVERE
WEATHER.
&&
.AVIATION /06Z MONDAY THROUGH THURSDAY/...
AS OF 236 AM MONDAY...
LIFR TO IFR CIGS ALONG WITH MVFR VSBYS EXPECTED THROUGH 15Z/MON.
SCATTERED TO NUMEROUS SHOWERS ARE EXPECTED ESPECIALLY FROM KFAY TO
KRDU THROUGH 12Z/MON. IFR TO MVFR CIGS ARE EXPECTED THROUGH THE DAY
WITH NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS... ESPECIALLY EAST
OF KINT/KGSO.... WHERE THE SHOWERS SHOULD BE MORE SCATTERED.
IFR TO LIFR CIGS AND VSBYS SHOULD DEVELOP TONIGHT AND PERSIST INTO
EARLY TUESDAY (13Z-15Z)... THE SCATTERED OUT TO VFR. A FEW SHOWERS
AND THUNDERSTORMS MAY DEVELOP TUESDAY AFTERNOON.
LOW STRATUS AND FOG WILL AGAIN BE PROBLEMATIC TUESDAY NIGHT INTO
EARLY WED... THEN GENERALLY VFR CONDITIONS WED THROUGH THU.
HOWEVER... SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
AGAIN LATE WED AFTERNOON AND ESPECIALLY THURSDAY AS ANOTHER TROUGH
APPROACHES FROM THE WEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON TUESDAY
REDUCING THE THREAT OF LOCALLY HEAVY RAIN.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 230 AM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
THE SLOW MOVING... ALMOST STUCK MID/UPPER LEVEL TROUGH... LOCATED
OVER WESTERN NC/SC IS EXPECTED TO ONLY SLOWLY BUDGE EASTWARD TODAY
AND TONIGHT. THIS IS A BIT SLOWER THAN HAD BEEN ADVERTISED BY
PREVIOUS MODELS... AND PUTS MUCH OF CENTRAL NORTH CAROLINA IN THE
REGION OF A LOCALLY HEAVY RAIN THREAT TODAY INTO TONIGHT. THE LATEST
MODEL FORECASTS INCLUDING THE HI-RES HRRR GUIDANCE WERE DEPICTING
MUCH OF THE EASTERN PIEDMONT... SANDHILLS AND PORTIONS OF THE
COASTAL PLAIN IN A REGION OF SIGNIFICANT LIFT OUT AHEAD OF THE TROUGH
THROUGH TONIGHT. THE HI-RES HRRR HAD A DECENT HANDLE ON THE CURRENT
AREAS OF SHOWERS. WE WILL GENERALLY FOLLOW THE FORECAST OUTPUT OF
CONVECTION THROUGH THE NEXT 6 HOURS... OR UNTIL SURFACE HEATING
TAKES OVER. THE AREA OF SHOWERS OVER THE SOUTHERN PIEDMONT
AND SANDHILLS SHOULD MOVE SLOWLY NNE INTO THE FAYETTEVILLE AND
RALEIGH AREAS THROUGH DAYBREAK... THEN WEAKEN OUT OVER THE
CENTRAL/NORTHERN COASTAL PLAIN THEREAFTER.
CONVECTION SHOULD AGAIN BLOSSOM THIS AFTERNOON WITH DIFFERENTIAL
HEATING WITH BREAKS IN THE CLOUDS AIDED BY THE SLUG OF COLDER AIR
ALOFT INCREASING LOW LEVEL INSTABILITY. THE INCREASINGLY WEAK
STEERING FLOW SHOULD ALLOW FOR SLOWER MOVING CONVECTION THIS
AFTERNOON AND EVENING... THAN OBSERVED SUNDAY. IN ADDITION... THE
PROLONGED SE FLOW FROM OFF THE GULF STREAM AND WESTERN ATLANTIC WILL
INCREASE DEW POINTS TO NEAR 70 THIS AFTERNOON. THIS POOLING OF DEEP
MOISTURE WITH PRECIPITABLE WATER VALUE FORECASTS ON THE ORDER OF
1.75 INCHES OVER THE EASTERN PIEDMONT AND WESTERN COASTAL PLAIN
SUGGEST A HEAVY RAIN THREAT. THE LACK OF A SIGNIFICANT LOW LEVEL
BOUNDARY AT THE CURRENT TIME SUGGESTS FLOODING WOULD PROBABLY BE
MORE LOCALIZED. THE HAZARDOUS WEATHER OUTLOOK WILL CONTINUE TO
HIGHLIGHT MAINLY URBAN AND SMALL STREAM FLOODING POTENTIAL WITH THE
LOCALLY HEAVY RAIN. HIGHS TODAY SHOULD INCH A BIT HIGHER THAN SUNDAY
WITH A FEW MORE BREAKS IN THE CLOUDS IN THE MORNING. HIGHS GENERALLY
78 TO 83.
SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 250 AM MONDAY...
A CONTINUED WEAKENING TREND WITH THE TROUGH AND A GRADUAL SHIFT
EASTWARD WILL MEAN MORE SCATTERED AND LESS CONCENTRATED CONVECTIVE
RAINFALL ON TUESDAY AFTERNOON AND EVENING. SEVERAL MODEL SOLUTIONS
INDICATE THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM THE WESTERN
ATLANTIC OVER PORTIONS OF NC. AFTER A START TO THE DAY WITH LOW
STRATUS AND AREAS OF FOG... PARTLY SUNNY SKIES ARE EXPECTED. HIGHS
SHOULD REBOUND INTO THE LOWER TO MID 80S. HOWEVER... DEW POINTS WILL
STILL BE IN THE MID TO UPPER 60S. THE COOLER MET/NAM GUIDANCE LOOKS
MORE IN LINE WITH THE CURRENT EXPECTATIONS WITH THE SSW FLOW AND
PLENTY OF LOW LEVEL MOISTURE AND BROKEN AFTERNOON CLOUDINESS. WIDELY
SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED. THIS
ACTIVITY WILL DIMINISH TUESDAY EVENING WITH LOSS OF HEATING. PARTLY
CLOUDY SKIES WITH AREAS OF FOG AGAIN EXPECTED LATE AT NIGHT. LOWS IN
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 245 PM SUNDAY...
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WEEK WITH THE APPROACH OF OUR NEXT MID/UPPER LEVEL
TROUGH AND ASSOCIATED COLD FRONT. THERE IS STILL SOME UNCERTAINTY
(MAINLY DUE TO RUN TO RUN INCONSISTENCIES) WITH THE TIMING OF THE
COLD FRONTAL PASSAGE...BUT OVERALL THE TREND HAS BEEN WITH A QUICKER
PASSAGE. IN FACT...THE MODELS ARE IN GENERAL AGREEMENT WITH BRINGING
THE FRONT THROUGH THE FORECAST AREA EARLY FRIDAY...ALMOST 12-18
HOURS EARLIER THAN WHAT MODELS INDICATED 24 HOURS AGO.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. AS OF NOW...IT NOW APPEARS THE WEEKEND
WILL BE DRY AS HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT.
WITH INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND FRIDAY...TEMPS
WILL MOSTLY BE IN THE LOW/MID 80S...WITH SLIGHTLY COOLER TEMPS
EXPECTED FOR THE WEEKEND (GENERALLY IN THE 70S).
&&
.AVIATION /06Z MONDAY THROUGH THURSDAY/...
AS OF 236 AM MONDAY...
LIFR TO IFR CIGS ALONG WITH MVFR VSBYS EXPECTED THROUGH 15Z/MON.
SCATTERED TO NUMEROUS SHOWERS ARE EXPECTED ESPECIALLY FROM KFAY TO
KRDU THROUGH 12Z/MON. IFR TO MVFR CIGS ARE EXPECTED THROUGH THE DAY
WITH NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS... ESPECIALLY EAST
OF KINT/KGSO.... WHERE THE SHOWERS SHOULD BE MORE SCATTERED.
IFR TO LIFR CIGS AND VSBYS SHOULD DEVELOP TONIGHT AND PERSIST INTO
EARLY TUESDAY (13Z-15Z)... THE SCATTERED OUT TO VFR. A FEW SHOWERS
AND THUNDERSTORMS MAY DEVELOP TUESDAY AFTERNOON.
LOW STRATUS AND FOG WILL AGAIN BE PROBLEMATIC TUESDAY NIGHT INTO
EARLY WED... THEN GENERALLY VFR CONDITIONS WED THROUGH THU.
HOWEVER... SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
AGAIN LATE WED AFTERNOON AND ESPECIALLY THURSDAY AS ANOTHER TROUGH
APPROACHES FROM THE WEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BADGETT
SHORT TERM...BADGETT
LONG TERM...KRR
AVIATION...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
236 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON TUESDAY
REDUCING THE THREAT OF LOCALLY HEAVY RAIN.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 230 AM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
THE SLOW MOVING... ALMOST STUCK MID/UPPER LEVEL TROUGH... LOCATED
OVER WESTERN NC/SC IS EXPECTED TO ONLY SLOWLY BUDGE EASTWARD TODAY
AND TONIGHT. THIS IS A BIT SLOWER THAN HAD BEEN ADVERTISED BY
PREVIOUS MODELS... AND PUTS MUCH OF CENTRAL NORTH CAROLINA IN THE
REGION OF A LOCALLY HEAVY RAIN THREAT TODAY INTO TONIGHT. THE LATEST
MODEL FORECASTS INCLUDING THE HI-RES HRRR GUIDANCE WERE DEPICTING
MUCH OF THE EASTERN PIEDMONT... SANDHILLS AND PORTIONS OF THE
COASTAL PLAIN IN A REGION OF SIGNIFICANT LIFT OUT AHEAD OF THE TROUGH
THROUGH TONIGHT. THE HI-RES HRRR HAD A DECENT HANDLE ON THE CURRENT
AREAS OF SHOWERS. WE WILL GENERALLY FOLLOW THE FORECAST OUTPUT OF
CONVECTION THROUGH THE NEXT 6 HOURS... OR UNTIL SURFACE HEATING
TAKES OVER. THE AREA OF SHOWERS OVER THE SOUTHERN PIEDMONT
AND SANDHILLS SHOULD MOVE SLOWLY NNE INTO THE FAYETTEVILLE AND
RALEIGH AREAS THROUGH DAYBREAK... THEN WEAKEN OUT OVER THE
CENTRAL/NORTHERN COASTAL PLAIN THEREAFTER.
CONVECTION SHOULD AGAIN BLOSSOM THIS AFTERNOON WITH DIFFERENTIAL
HEATING WITH BREAKS IN THE CLOUDS AIDED BY THE SLUG OF COLDER AIR
ALOFT INCREASING LOW LEVEL INSTABILITY. THE INCREASINGLY WEAK
STEERING FLOW SHOULD ALLOW FOR SLOWER MOVING CONVECTION THIS
AFTERNOON AND EVENING... THAN OBSERVED SUNDAY. IN ADDITION... THE
PROLONGED SE FLOW FROM OFF THE GULF STREAM AND WESTERN ATLANTIC WILL
INCREASE DEW POINTS TO NEAR 70 THIS AFTERNOON. THIS POOLING OF DEEP
MOISTURE WITH PRECIPITABLE WATER VALUE FORECASTS ON THE ORDER OF
1.75 INCHES OVER THE EASTERN PIEDMONT AND WESTERN COASTAL PLAIN
SUGGEST A HEAVY RAIN THREAT. THE LACK OF A SIGNIFICANT LOW LEVEL
BOUNDARY AT THE CURRENT TIME SUGGESTS FLOODING WOULD PROBABLY BE
MORE LOCALIZED. THE HAZARDOUS WEATHER OUTLOOK WILL CONTINUE TO
HIGHLIGHT MAINLY URBAN AND SMALL STREAM FLOODING POTENTIAL WITH THE
LOCALLY HEAVY RAIN. HIGHS TODAY SHOULD INCH A BIT HIGHER THAN SUNDAY
WITH A FEW MORE BREAKS IN THE CLOUDS IN THE MORNING. HIGHS GENERALLY
78 TO 83.
SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 245 PM SUNDAY...
THE MID/UPPER LEVEL WAVE (CAUSING ALL OF THE RAIN TODAY AND MONDAY)
WILL STILL BE LINGERING ACROSS THE EASTERN PORTIONS OF THE FORECAST
AREA ON TUESDAY...BEFORE FINALLY SHIFTING OFFSHORE TUESDAY NIGHT.
THEREFORE...SHOWER AND THUNDERSTORM CHANCES WILL REMAIN ELEVATED...
ALTHOUGH COVERAGE SHOULD BE LESS THAN PREVIOUS DAYS. THE HIGHEST
POPS ARE EXPECTED ACROSS THE EAST...AS THE WESTERN PORTIONS OF THE
FORECAST AREA MAY HAVE CONVECTIVE ACTIVITY MORE SUPPRESSED DUE TO
INCREASING SUBSIDENCE OF THE BACKSIDE OF TROUGH AXIS. HIGHS SHOULD
BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS GENERALLY IN THE MID
60S.
SOME WEAK SHORTWAVE RIDGING WILL START TO BUILD OVER THE AREA BY
WEDNESDAY...WHILE AT THE SURFACE...THE BERMUDA HIGH WILL START TO
RIDGE WESTWARD INTO THE CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN
EVEN FURTHER DECREASE IN PRECIP COVERAGE ON WEDNESDAY. HOWEVER...
SUFFICIENT MOISTURE WILL STILL BE IN PLACE OVER THE REGION...WITH
PWAT VALUES HOVERING NEAR 1.5 INCHES OR SO. THEREFORE...AM STILL
EXPECTING TO SEE WIDELY SCATTERED TO SCATTERED DIURNALLY DRIVEN
CONVECTION. HIGHS ONCE AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH
OVERNIGHT LOWS IN THE MID/UPPER 60S.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 245 PM SUNDAY...
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WEEK WITH THE APPROACH OF OUR NEXT MID/UPPER LEVEL
TROUGH AND ASSOCIATED COLD FRONT. THERE IS STILL SOME UNCERTAINTY
(MAINLY DUE TO RUN TO RUN INCONSISTENCIES) WITH THE TIMING OF THE
COLD FRONTAL PASSAGE...BUT OVERALL THE TREND HAS BEEN WITH A QUICKER
PASSAGE. IN FACT...THE MODELS ARE IN GENERAL AGREEMENT WITH BRINGING
THE FRONT THROUGH THE FORECAST AREA EARLY FRIDAY...ALMOST 12-18
HOURS EARLIER THAN WHAT MODELS INDICATED 24 HOURS AGO.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. AS OF NOW...IT NOW APPEARS THE WEEKEND
WILL BE DRY AS HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT.
WITH INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND FRIDAY...TEMPS
WILL MOSTLY BE IN THE LOW/MID 80S...WITH SLIGHTLY COOLER TEMPS
EXPECTED FOR THE WEEKEND (GENERALLY IN THE 70S).
&&
.AVIATION /06Z MONDAY THROUGH THURSDAY/...
AS OF 236 AM MONDAY...
LIFR TO IFR CIGS ALONG WITH MVFR VSBYS EXPECTED THROUGH 15Z/MON.
SCATTERED TO NUMEROUS SHOWERS ARE EXPECTED ESPECIALLY FROM KFAY TO
KRDU THROUGH 12Z/MON. IFR TO MVFR CIGS ARE EXPECTED THROUGH THE DAY
WITH NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS... ESPECIALLY EAST
OF KINT/KGSO.... WHERE THE SHOWERS SHOULD BE MORE SCATTERED.
IFR TO LIFR CIGS AND VSBYS SHOULD DEVELOP TONIGHT AND PERSIST INTO
EARLY TUESDAY (13Z-15Z)... THE SCATTERED OUT TO VFR. A FEW SHOWERS
AND THUNDERSTORMS MAY DEVELOP TUESDAY AFTERNOON.
LOW STRATUS AND FOG WILL AGAIN BE PROBLEMATIC TUESDAY NIGHT INTO
EARLY WED... THEN GENERALLY VFR CONDITIONS WED THROUGH THU.
HOWEVER... SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
AGAIN LATE WED AFTERNOON AND ESPECIALLY THURSDAY AS ANOTHER TROUGH
APPROACHES FROM THE WEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...BADGETT
SHORT TERM...KRR
LONG TERM...KRR
AVIATION...BADGETT
AREA FORECAST DISCUSSION...CORRECTED
NWS CLEVELAND OH
359 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TODAY IS A TOUGH FORECAST. THE HRRR AND RUC/RAP MODELS HAVE BEEN
FORECASTING A NARROW BAND OF SHOWERS/THUNDERSTORMS TO DEVELOP OVER
EASTERN INDIANA EARLY THIS MORNING AND THEN MOVE EAST. AT 3 AM EDT
THE ILN 88D WAS INDICATING A FINE LINE OVER SE INDIANA. AS EACH HOUR
HAS GONE ON THE MODELS ARE DELAYING THE DEVELOPMENT AND INTENSITY OF
THE PRECIPITATION. NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING
ON THIS LINE UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH.
SOME OF THE RADAR FORECAST OUTPUT FROM SPC STORM-SCALE
ENSEMBLE OF OPPORTUNITY MODELS ARE ALL OVER THE PLACE FOR
TODAY...SOME WITH NO SHOWER OR THUNDERSTORM DEVELOPMENT IN THE
FORECAST AREA AND SOME WITH A LITTLE DEVELOPMENT. THE 4KM WRF NMM
MODEL HAS SOME ISOLATED SHOWERS DEVELOPING. CONFIDENCE IS LOW IN
THIS BECAUSE OF SO MUCH RIDGING ALOFT...BUT WILL FORECAST A CHANCE
OF SPRINKLES MAINLY THIS AM AS THIS LINE MOVES THROUGH. WILL
MONITOR THIS AND UPDATE AS NEEDED.
ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.
NOT MUCH IN THE WAY OF CLOUDS ACROSS THE FORECAST AREA AT 4
AM...HOWEVER...THEY ARE EXPECTED TO DEVELOP THROUGH DAYBREAK.
PARTLY CLOUDY SHOULD HANDLE MOST OF TODAY.
OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT
EXPECTING MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO
STRONG. ERIE MAY GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT
ON THE WARMER SIDE OF GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING
SOUTHWEST FLOW AND WARMER AIR ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.
FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.
FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.
USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.
RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.
THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED. BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
WITH DEW POINTS CREEPING INTO THE 60S DO EXPECT MORE MVFR BR THIS
MORNING...BUT WIND SHOULD HELP IT FROM BEING TOO WIDESPREAD. SHORT
TERM MODELS NOT IN AGREEMENT ON THE TSRA IN ILLINOIS...LATEST HRR
MOVE TSRA INTO NW OH BY 12Z. FOR NOW WILL ONLY ADD VCTS TO TOL AND
FDY SINCE CONFIDENCE IS LOW AT THIS TIME.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS MONDAY
EVENING THROUGH THURSDAY.
&&
.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS. EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM. MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY. WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
357 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TODAY IS A TOUGH FORECAST. THE HRRR AND RUC/RAP MODELS HAVE BEEN
FORECASTING A NARROW BAND OF SHOWERS/THUNDERSTORMS TO DEVELOP OVER
EASTERN INDIANA EARLY THIS MORNING AND THEN MOVE EAST. AT 3 AM EDT
THE ILN 88D WAS INDICATING A FINE LINE OVER SE INDIANA. AS EACH HOUR
HAS GONE ON THE MODELS ARE DELAYING THE DEVELOPMENT AND INTENSITY OF
THE PRECIPITATION. NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING
ON THIS LINE UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH.
SOME OF THE RADAR FORECAST OUTPUT FROM SPC STORM-SCALE
ENSEMBLE OF OPPORTUNITY MODELS ARE ALL OVER THE PLACE FOR
TODAY...SOME WITH NO SHOWER OR THUNDERSTORM DEVELOPMENT IN THE
FORECAST AREA AND SOME WITH A LITTLE DEVELOPMENT. THE 4KM WRF NMM
MODEL HAS SOME ISOLATED SHOWERS DEVELOPING. CONFIDENCE IS LOW IN
THIS BECAUSE OF SO MUCH RIDGING ALOFT...BUT WILL FORECAST A CHANCE
OF SPRINKLES MAINLY THIS AM AS THIS LINE MOVES THROUGH. WILL
MONITOR THIS AND UPDATE AS NEEDED.
ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.
OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT EXPECTING
MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO STRONG. ERIE MAY
GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT ON THE WARMER SIDE OF
GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING SOUTHWEST FLOW AND
WARMER AIR ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.
FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.
FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.
USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.
RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.
THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED. BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
WITH DEW POINTS CREEPING INTO THE 60S DO EXPECT MORE MVFR BR THIS
MORNING...BUT WIND SHOULD HELP IT FROM BEING TOO WIDESPREAD. SHORT
TERM MODELS NOT IN AGREEMENT ON THE TSRA IN ILLINOIS...LATEST HRR
MOVE TSRA INTO NW OH BY 12Z. FOR NOW WILL ONLY ADD VCTS TO TOL AND
FDY SINCE CONFIDENCE IS LOW AT THIS TIME.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS MONDAY
EVENING THROUGH THURSDAY.
&&
.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS. EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM. MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY. WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1203 AM CDT MON MAY 20 2013
.AVIATION...
FOR THE 06Z TAFS...NO SIGNIFICANT CHANGES IN THINKING FROM
PREVIOUS FORECAST...SO LEFT PREVIOUS DISCUSSION INCLUDED BELOW.
BUMPED UP THE TIMING OF STRATUS BASED ON IR SATELLITE IMAGERY OF
STRATUS SURGING NORTH ON THE 50 KT LOW LEVEL JET LATE THIS
EVENING.
THE DFW CWSU INDICATED THAT SEVERAL PILOTS AROUND DFW AIRSPACE
TODAY MENTIONED REDUCED VISIBILITIES WHILE IN FLIGHT/LANDING DUE
TO SMOKE TRAPPED UNDER THE STRONG CAPPING INVERSION OVER NORTH TX
TODAY. THE SMOKE CAME FROM FIRES IN NORTHERN MEXICO. THIS CAP IS
LIKELY TO REMAIN IN PLACE TOMORROW...SO THIS THIN LAYER OF SMOKE
WILL LIKELY CONTINUE TO REDUCE VISIBILITIES FOR PILOTS LANDING
AROUND NORTH TX AIRPORTS ON MONDAY. THERE IS NOT REALLY ANY WAY TO
ACCOUNT FOR THIS IN THE TAFS...THE SMOKE IS NOT THICK ENOUGH TO
RESULT IN A CLOUD LAYER...AND THE REDUCED VISIBILITIES OCCUR 4-6
THOUSAND FEET ALOFT AND NOT AT THE SURFACE. THEREFORE MENTIONED
THE ELEVATED SMOKE LAYER HERE AS SOME SORT OF HEADS UP TO PILOTS
THAT THIS THIN SMOKE LAYER IS LIKELY TO PERSIST THROUGH MONDAY.
CAVANAUGH
.../PREVIOUS AVIATION DISCUSSION/...
FOR THE 00Z TAFS...THUNDERSTORM CHANCES AND TIMING THE ONSET OF
MVFR STRATUS ARE THE PRIMARY FORECAST CONCERNS THROUGH THE VALID
FORECAST PERIOD.
THUNDERSTORM CHANCES...WENT AHEAD AND LEFT THUNDERSTORMS OUT OF
THE METROPLEX AREA TAFS FOR THIS EVENING BASED LARGELY ON
SATELLITE OBSERVATIONS. THE LATEST RAP FORECAST SOUNDINGS
INDICATED THAT THE CAP OVER THE DFW AREA WOULD ERODE BY 02Z
POSSIBLY RESULTING IN THUNDERSTORMS NEAR AREA TAF SITES. VISIBLE
SATELLITE IMAGERY INDICATES FLAT CUMULUS CLOUDS WHILE IR SATELLITE
IMAGES SHOW CLOUD TOP TEMPERATURES HOLDING STEADY AT THE TIME OF
THIS DISCUSSION. EARLY RESULTS FROM THE 00Z FWD RAOB INDICATE A
SUBSTANTIAL CAP REMAINS IN PLACE OVER THE METROPLEX...HOWEVER AN
AIRCRAFT SOUNDING TAKING OFF FROM KDAL DID INDICATE A WEAKER CAP.
EITHER WAY...A CAP REMAINS IN PLACE AND IN THE ABSENCE OF STRONG
LIFT...DO NOT SEE A REASON FOR STORMS TO INITIATE NEAR AREA TAF
SITES THIS EVENING OR OVERNIGHT.
FOR TOMORROW...AN UPPER LEVEL DISTURBANCE OVER UTAH IS EXPECTED TO
MOVE TOWARDS THE REGION OVER THE NEXT 24 TO 36 HRS. THIS WILL
RESULT IN BETTER UPPER LEVEL SUPPORT AND LIFT ALONG THE DRYLINE BY
LATE TOMORROW AFTERNOON RESULTING IN A HIGHER CONFIDENCE FORECAST
FOR THUNDERSTORMS. STORMS THAT DEVELOP ALONG THE DRYLINE WOULD
LIKELY NOT REACH THE METROPLEX UNTIL AFTER 23Z OR 6 PM CDT. WENT
AHEAD WITH A MENTION OF VCTS IN ALL METROPLEX AREA TAFS AFTER THIS
TIME DUE TO THE HIGHER CONFIDENCE IN THE CLOSE PROXIMITY OF
STORMS. A CAPPING INVERSION IS EXPECTED TO REMAIN IN PLACE OVER
THE METROPLEX TOMORROW AFTERNOON...SO ITS DIFFICULT TO KNOW
WHETHER STORMS WILL BE ABLE TO OVERCOME THIS CAP OR NOT TO MOVE
DIRECTLY OVER AREA TAF SITES. EITHER WAY...THE STORMS ARE EXPECTED
TO BE CLOSE ENOUGH TO CAUSE TRAFFIC HEADACHES AT AREA AIRPORTS SO
THE VCTS IS IN THE FORECAST FOR PLANNING PURPOSES MORE THAN
ANYTHING ELSE AT THIS POINT.
MVFR STRATUS...NO CHANGES MADE TO THE PREVIOUS FORECAST. WE WILL
ONCE AGAIN HAVE A STRONG LOW-LEVEL JET OF 50 KTS OR GREATER OVER
NORTH TX TONIGHT. THIS SHOULD RESULT IN A SIMILAR STRATUS TIMING
TO THIS MORNING WHERE STRATUS BUILT OVER METROPLEX TAF SITES AFTER
11Z. STRATUS SHOULD SCATTER OUT OR LIFT TO VFR LEVELS QUICKLY WITH
DRIER AIR ABOVE THE STRATUS DECK ABOVE THE CAP.
CAVANAUGH
&&
.PREV DISCUSSION... /ISSUED 328 PM CDT SUN MAY 19 2013/
THE DRYLINE HAS REACHED A LINE FROM WICHITA FALLS TO GRAHAM TO
BROWNWOOD WHERE IT WILL LIKELY STALL BEFORE RETREATING WEST THIS
EVENING. THE MAIN FORECAST CONCERN THROUGH THIS EVENING IS
WHETHER STORMS WILL INITIATE ALONG THE DRYLINE AND THE AMOUNT OF
COVERAGE. AS DISCUSSED IN THE MORNING UPDATE...MOST OF THE MODEL
GUIDANCE IS NOT INITIATING ANY CONVECTION IN OUR REGION THIS
EVENING DESPITE CIN BECOMING ALMOST NEGLIGIBLE ACROSS THE WESTERN
ZONES. HOWEVER THE RUC/HRRR/GFS HAVE NOT WAVERED AND ONE OF THE
HI-RES WRFS AT 12Z HAS NOW JOINED THE INITIATION CAMP. THE ISSUE
AT HAND IS LIKELY THAT TODAY/S STRONG WINDS AND DRY AIR ALOFT WILL
MAKE IT TOUGH FOR AN INFANT UPDRAFT TO BECOME ESTABLISHED AND
GROW INTO A SUPERCELL WITHOUT A SHORTWAVE TO AID IN LIFT. RIGHT
NOW THE BEST GUESS IS THAT 1 TO 3 STORMS WILL MANAGE TO DEVELOP
OVER THE WESTERN CWA BY EARLY EVENING...AND WILL CONTINUE THE
FORECAST OF 20-30 POPS WEST OF A LINE FROM SHERMAN TO DFW TO
LAMPASAS. LOCAL OBJECTIVE ANALYSIS INDICATES CAPE VALUES ARE FROM
2000-3000 J/KG OVER THE CWA AND AMPLE DEEP LAYER SHEAR EXISTS TO
SUPPORT VERY LARGE HAIL AND DAMAGING WINDS. AN ISOLATED TORNADO
WILL BE POSSIBLE BETWEEN 6 AND 8 PM WHEN LOW LEVEL WIND SHEAR
RAMPS UP JUST BEFORE THE SURFACE AIRMASS BECOMES TOO NEGATIVELY
BUOYANT WITH LOSS OF HEATING. STORMS MAY HOLD TOGETHER LONG ENOUGH
TO AFFECT LOCATIONS FARTHER TO THE EAST BY MID-LATE
EVENING...ESPECIALLY NORTH OF I-20...BUT SEVERE WEATHER POTENTIAL
WILL BE DIMINISHING. OTHERWISE A BREEZY AND MUGGY NIGHT IS IN
STORE FOR THE REGION.
THE STORM THREAT FOR MONDAY IS LOOKING GREATER ACROSS A LARGER
PART OF NORTH TEXAS. THE CIN WILL BE EVEN WEAKER THAN TODAY AND
ALMOST ALL OF THE MODELS ARE INDICATING STORM INITIATION IN THE
CWA. THE DRYLINE WILL BE ROUGHLY IN THE SAME LOCATION AS IT IS
TODAY. THE GFS AND NAM ARE MOST AGGRESSIVE WITH HEIGHT FALLS AND
CONVECTION ACROSS THE NW CWA...WHICH RAISES CONFIDENCE THAT THIS
AREA WILL LIKELY SEE SUPERCELL STORMS AND SEVERE WEATHER. EXPECT
SEVERAL SUPERCELLS TO DEVELOP ACROSS THE WESTERN ZONES...INCLUDING
SOME ISOLATED CELLS ACROSS THE SW ZONES. VERY HIGH INSTABILITY
AND AMPLE DEEP LAYER SHEAR WILL SUPPORT A THREAT OF SIGNIFICANT
SEVERE WEATHER INCLUDING GIANT HAIL...DAMAGING WINDS AND A FEW
TORNADOES. LOW LEVEL WIND SHEAR GETS STRONGER AFTER 7PM WITH 0-3KM
SRH VALUES ABOVE 300 M2/S2. SINCE THERE IS LESS CIN THERE IS MORE
TIME FOR EVENING SUPERCELLS TO TAP INTO THIS INSTABILITY AFTER
DARK WHICH IS WHAT IS RAISING OUR CONCERN FOR TORNADOES. HAVE
BUMPED UP POPS TO 30-50 PERCENT IN THE WESTERN ZONES...AND
RAISED THEM FOR THE CENTRAL AND NORTHEAST ZONES AS WELL...AS
SUPERCELLS WILL HEAD EASTWARD AND HOLD TOGETHER LONGER.
ON TUESDAY A WEAK COLD FRONT WILL BECOME DRAPED ACROSS THE CWA
FROM ROUGHLY PARIS TO DFW TO EASTLAND. HIGH TEMPS WILL BE A LITTLE
COOLER THIS DAY...BUT INSTABILITY WILL STILL BE VERY HIGH
ESPECIALLY ACROSS THE SOUTHERN ZONES. ALL MODEL GUIDANCE SHOWS
STRONG UPPER LEVEL FORCING OVER NORTH TEXAS TUESDAY AFTERNOON AS
THE TROUGH AXIS SWINGS THROUGH THE AREA. THIS WILL SET THE STAGE
FOR SCATTERED TO NUMEROUS SHOWERS AND STORMS THAT WILL LIKELY
DEVELOP ALONG THE FRONT TUESDAY AFTERNOON AND MOVE EAST AND
SOUTHEAST INTO THE NIGHTTIME HOURS. SINCE LOW LEVEL WIND FIELDS
RELAX A BIT...THESE STORMS MAY TEND TO ORGANIZE INTO A MCS/SQUALL
LINE OVER THE CENTRAL ZONES. OBVIOUSLY A SEVERE WEATHER THREAT
WILL EXIST WITH THIS CONVECTIVE EPISODE AS WELL. RAINFALL WILL
RANGE FROM A TRACE IN THE NW TO 1.5 INCHES IN THE SOUTHEAST ZONES.
EXPECT THIS CONVECTIVE EPISODE TO FINALLY EXHAUST THE ATMOSPHERE
AND PUSH THE BEST MOISTURE AND INSTABILITY SOUTHEAST OF THE AREA
BY WEDNESDAY MORNING. WILL KEEP WEDNESDAY DRY.
WEAK RIDGING SETS UP OVER THE AREA WEDNESDAY AND INTO NEXT
WEEKEND. SOUTHEAST WINDS WILL CONTINUE WHICH WILL KEEP LOW TEMPS
IN THE MID 60S TO NEAR 70...AND HIGHS IN THE MID 80S TO NEAR 90
EACH DAY. CONVECTION IS EXPECTED TO OCCUR OVER THE HIGH PLAINS
THURSDAY AND FRIDAY...AND WITH A SOUTHEASTERLY FLOW IN THE LOWEST
800MB WE WILL NEED TO KEEP AN EYE ON SOME OF THIS ACTIVITY MAKING
A RUN AT THE CWA DURING THE OVERNIGHT HOURS. SINCE THERE IS A LACK
OF STRONG NORTHWEST FLOW ALOFT IN THE MID LEVELS...BELIEVE
CONVECTION WILL DISSIPATE BEFORE REACHING MOST OF THE AREA...BUT
HAVE INSERTED A SLIGHT CHANCE IN THE NW ZONES THURSDAY AND FRIDAY
NIGHTS. WILL KEEP THE REMAINDER OF THE FORECAST DRY.
TR.92
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 90 71 88 67 / 5 20 40 50 50
WACO, TX 72 90 72 91 68 / 5 10 20 40 60
PARIS, TX 70 87 69 83 65 / 5 10 60 50 50
DENTON, TX 70 89 69 86 64 / 5 30 40 40 40
MCKINNEY, TX 70 89 70 85 65 / 5 20 40 50 50
DALLAS, TX 73 91 73 89 69 / 5 20 40 50 50
TERRELL, TX 70 89 71 87 68 / 5 10 30 50 60
CORSICANA, TX 71 89 72 88 69 / 5 10 20 40 60
TEMPLE, TX 71 90 72 92 69 / 5 10 20 40 60
MINERAL WELLS, TX 70 94 68 88 65 / 5 30 30 40 40
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
341 AM CDT MON MAY 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT MON MAY 20 2013
MAIN FORECAST CONCERN IS ON SEVERE WEATHER AND FLOODING POTENTIAL
TODAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED AN UPPER LOW OVER SOUTH DAKOTA AND NEBRASKA WITH RIDGING
AHEAD OF IT OVER MICHIGAN. THE UPPER LOW WAS MOSTLY CUT OFF WITH
RIDGING TO ITS NORTH OVER SOUTH CENTRAL CANADA. 500MB STANDARD
DEVIATIONS WERE 1-1.5 BELOW NORMAL WITH THE UPPER LOW. NUMEROUS
SHORTWAVES WERE EJECTING IN SOUTHWEST FLOW AHEAD OF THE UPPER
LOW...SOME OF WHICH ARE CONVECTIVELY PRODUCED. ONE FOR EXAMPLE WAS
LIFTING THROUGH NORTHWEST WISCONSIN WHICH BROUGHT RAIN TO MUCH OF
THE AREA DURING THE NIGHTTIME HOURS. RAP DATA ALSO SHOWED A LOW
LEVEL MOISTURE TRANSPORT ZONE WITH THIS MCV. FARTHER SOUTH...ANOTHER
LOW LEVEL MOISTURE TRANSPORT ZONE WAS NOTED IN SOUTHERN MISSOURI...
POINTING INTO SOUTHERN ILLINOIS. COMBINATION OF SUBSIDENCE IN THE
WAKE OF THE MCV AND SPLIT IN MOISTURE TRANSPORT HAS ALLOWED THE
PRECIPITATION TO DIMINISH SOUTH OF HWY 29. PLENTIFUL MOISTURE COMING
UP AHEAD OF THE UPPER LOW WITH PRECIPITABLE WATER VALUES OF 1.2-1.5
INCHES FROM EASTERN OK INTO SOUTEHRN WI. THERE WAS A MINIMA OF
PRECIPITABLE WATER FROM WESTERN KS INTO MUCH OF IA...THOUGH....
ASSOCIATED WITH A DRY SLOT SOUTH OF THE UPPER LOW. AT THE
SURFACE...LOW PRESSURE WAS SITUATED UNDER THE UPPER LOW WITH A WARM
FRONT EXTENDING EAST TO EAU CLAIRE WI. RAP 850MB TEMPS WERE IN THE
14-18C RANGE SOUTH OF THE FRONT IN THE FORECAST AREA.
MODELS ARE IN GOOD AGREEMENT OF KEEPING THE UPPER LOW NEARLY
STATIONARY OVER SOUTH DAKOTA. DESPITE ITS STATIONARY MOVEMENT...THE
WEATHER WILL BE QUITE A BIT DIFFERENT COMPARED TO YESTERDAY.
PRIMARILY THIS IS DUE TO THE UPPER FLOW AHEAD OF THE UPPER LOW
PROGGED MORE SOUTHWESTERLY VERSUS SOUTHERLY. ADDITIONALLY...THE
PLUME OF HIGHER PRECIPITABLE WATER IS PROGGED TO SLOWLY SHIFT EAST
THANKS TO THE UPPER LOW.
MOST OF THE FORECAST AREA IS INDICATED TO STAY IN THE WARM SECTOR
THROUGH TONIGHT...ALONG WITH EXISTING IN THAT SOUTHWEST FLOW FOR
SHORTWAVES TO COME THROUGH...BOTH FAVORABLE FOR THUNDERSTORM
DEVELOPMENT. HOWEVER...ONE QUESTION MARK IS MOISTURE. BASED ON A
AMDAR SOUNDING OUT OF OMAHA AT 04Z...THE 850MB DEWPOINTS FROM THE
20.00Z NAM WERE 6-7C TOO HIGH...THUS THE NAM BUILDS A LOT OF CAPE
QUICKLY THIS MORNING. THE RAP IS MUCH MORE SUBDUED HAVING THE AREA
ENCOMPASSED BY THE DRY AIR...ESPECIALLY WHEN LOOKING AT MLCAPE.
THINKING THE RAP IDEA IS MUCH MORE REPRESENTATIVE AND HAVE KEPT THE
AREA DRY THROUGH EARLY AFTERNOON. EVENTUALLY...THE RAP DOES CATCH UP
WITH THE CAPE LATE IN THE AFTERNOON THANKS TO EVAPOTRANSPORATION OF
MOIST SOILS. IN FACT...THE RAP SHOWS A DEFINITIVE DRY LINE IN THE
WARM SECTOR FORMING NEAR I-35 IN THE AFTERNOON. THIS DRY LINE SHOULD
SERVE AS A TRIGGER FOR CONVECTIVE DEVELOPMENT...ESPECIALLY IN
SOUTHEAST MN AND NORTHEAST IA. MAJORITY OF MODELS...INCLUDING HI
RESOLUTION ONES...SHOW THIS SCENARIO...WITH THE THUNDERSTORMS THEN
PROPAGATING NORTHEAST THROUGH THE EVENING. THE BEST 0-6KM SHEAR OF
GREATER THAN 35 KTS IS PROGGED OVER THE SOUTHEAST HALF OF THE
FORECAST AREA...OPPOSITE OF WHERE MOST OF THE CONVECTION WILL BE. ON
THE OTHER HAND...FREEZING LEVEL HEIGHTS ARE LOWER ON THE ORDER OF
10500 FT WHERE THE CONVECTION IS EXPECTED...THUS THERE COULD END UP
BEING MARGINALLY SEVERE HAIL. STORMS SHOULD GRADUALLY WEAKEN AS
INSTABILITY WANES LATE IN THE EVENING INTO THE OVERNIGHT HOURS. IT
SHOULD BE NOTED...IF FOR SOME REASON A STORM FIRES IN THE HIGHER
0-6KM SHEAR AREA THIS AFTERNOON...IT WOULD LIKELY BECOME
SUPERCELLULAR. AGAIN...THOUGH...THINK THIS IS A LOW PROBABILITY WITH
THAT AREA PERHAPS EVEN BEING CAPPED. SEE THE HYDROLOGY SECTION BELOW
FOR FLOODING CONCERNS.
CERTAINTLY THE ADDITIONAL RAIN FROM STORMS THIS AFTERNOON AND EARLY
EVENING WILL NOT HELP THE FLOODING MATTERS IN PORTIONS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA. HAVE KEPT THE FLASH FLOOD WATCH GOING
TO 00Z THIS EVENING...WHICH WORKS OUT WELL IN TERMS OF TIME BECAUSE
THE CONVECTION SHOULD MOSTLY BE EAST OF THERE BY THE EXPIRATION.
SHOULD SEE QUITE A BIT OF SUN TODAY AND WITH 850MB TEMPS HOVERING IN
THAT 14-18C RANGE...TEMPERATURES SHOULD EASILY CLIMB INTO THE UPPER
70S TO MID 80S. ANOTHER MILD NIGHT LIKELY TONIGHT WITH PLENTY OF
CLOUDS AND DEWPOINTS REMAINING UP IN THE 50S TO LOW 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 341 AM CDT MON MAY 20 2013
TUESDAY THROUGH THURSDAY...
MAIN FOCUS HERE IS ON THE EVOLUTION OF THE UPPER LOW. 20.00Z
ECMWF/GFS/CANADIAN/NAM ARE ALL IN PRETTY GOOD AGREEMENT HOLDING THE
UPPER LOW NEARLY STATIONARY ON TUESDAY...THEN GRADUALLY SHIFTING
EASTWARD TUESDAY NIGHT AND WEDNESDAY BEFORE IT GETS MORE OF A KICK
EAST WEDNESDAY NIGHT. THE KICK EAST IS IN RESPONSE TO A POTENT
TROUGH DROPPING SOUTH THROUGH MUCH OF EASTERN CANADA.
FOR TUESDAY...MUCH OF THE FORECAST AREA WEST OF THE MISSISSIPPI
RIVER LOOKS TO BE DRY-SLOTTED...THUS HAVE LOWERED PRECIPITATION
CHANCES. TO THE EAST...THERE ARE INDICATIONS THAT SOME DIURNAL
CONVECTION COULD FORM ALONG A COLD FRONT MARCHING EAST. INSTABILITY
IS PRETTY MEAGER IN THIS CASE COMPARED TO WHAT WE HAVE BEEN DEALING
WITH...THUS ANY CONVECTION SHOULD NOT GO SEVERE. BETTER SHOT FOR
SEVERE WEATHER WILL BE WELL SOUTH AND EAST OF THE FORECAST AREA.
HIGHEST PRECIPITATION CHANCES OVERALL ARE EXPECTED NORTH OF HWY 29
IN A LOW TO MID LEVEL FRONTOGENESIS ZONE.
AS THE UPPER LOW BEGINS TO PUSH EAST TOWARDS THE FORECAST AREA
TUESDAY NIGHT AND WEDNESDAY...DPVA INCREASES WHILE SIMULTANEOUSLY
THE LOW TO MID LEVEL FRONTOGENESIS ZONE DROPS SOUTH. THEREFORE...
INCREASING PRECIPITATION CHANCES SEEM REASONABLE... ESPECIALLY ON
WEDNESDAY WHEN THE TWO FORCING MECHANISMS ARE JUXTAPOSTED.
ADDITIONALLY...THERE COULD BE SOME DIURNAL ENHANCEMENT ON WEDNESDAY
BEING CLOSE TO OR UNDER THE COLD CORE OF THE UPPER LOW.
MODELS APPEAR TO BE TRENDING FASTER IN KICKING OUT THE UPPER LOW FOR
WEDNESDAY NIGHT AND THURSDAY...ENOUGH SO THAT THURSDAY MAY NOW END
UP DRY. WEDNESDAY NIGHT STILL LOOKS FAVORABLE FOR PRECIPITATION...
ESPECIALLY EAST OF THE MISSISSIPPI RIVER WHICH IS IN THAT
AFOREMENTIONED JUXTAPOSITION OF FORCING MECHANISMS.
DEFINITELY A COOLING TREND WILL TAKE PLACE FOR TUESDAY THROUGH
THURSDAY WITH THAT UPPER LOW COMING IN...AND THEN COME THURSDAY A
NORTHERLY FLOW ADVECTING AIR FROM CANADIAN HIGH PRESSURE TRYING TO
BUILD SOUTH INTO THE UPPER GREAT LAKES. 850MB TEMPS FALL FROM 11-13C
AT 12Z TUE TO 4-6C BY 12Z THU. WENT WITH A BLEND OF GUIDANCE FOR
HIGHS AND LOWS FOR NOW GIVEN NO SIGNAL TO LEAN TOWARDS WARMER OR
COLDER SCENARIO GIVEN THE FORECAST PATTERN.
THURSDAY NIGHT INTO NEXT WEEKEND...
20.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES CONTINUE TO ADVERTISE A
BLOCKED UP UPPER LEVEL FLOW PATTERN ACROSS NORTH AMERICA DURING THE
EXTENDED PORTION OF THE FORECAST. THE FLOW FEATURES DEEP TROUGHING
ALONG THE WEST COAST...RIDGING FROM THE PLAINS INTO THE NORTHWEST
TERRITORIES...AND MEAN TROUGHING FROM EASTERN CANADA INTO THE
MID-ATLANTIC REGION. WHAT THIS PATTERN MEANS FOR THE FORECAST AREA
IS A BATTLE BETWEEN DRY...CANADIAN HIGH PRESSURE AND A MORE HUMID
AIRMASS ADVECTING NORTH OUT OF THE GULF OF MEXICO UNDER THE UPPER
RIDGE. IT APPEARS DRY CONDITIONS SHOULD PREVAIL FOR THURSDAY NIGHT
AND FRIDAY...RESULTING FROM SUBSIDENCE IN THE WAKE OF THE EARLY TO
MID WEEK UPPER LOW. FROM FRIDAY NIGHT AND BEYOND...HAVE FOLLOWED A
CONSENSUS APPROACH AND SPREAD PRECIPITATION CHANCES ACROSS THE
FORECAST AREA...HIGHEST WEST OF THE MISSISSIPPI RIVER. THESE CHANCES
ARE A RESULT OF SURGES OF WARM ADVECTION. THE PRECIPITATION COULD
BECOME ENHANCED TOO AT TIMES AS JET STREAKS PROPAGATE BETWEEN THE
EASTERN CANADA TROUGH AND PLAINS RIDGING.
SOMETHING TO WATCH DURING THE EXTENDED IS POTENTIAL FOR FROST...
ESPECIALLY IN CENTRAL WISCONSIN. THURSDAY NIGHT ACCORDING TO 20.00Z
MODELS WOULD BE THE HIGHEST CHANCE...THOUGH CONFIDENCE IS NOT HIGH
ENOUGH TO EITHER MENTION FROST IN THE FORECAST OR DROP LOWS BELOW
40. OTHERWISE...TEMPERATURES SHOULD STAY MOSTLY BELOW NORMAL BEING
UNDER THE INFLUENCE OF THE CANADIAN HIGH AND A NORTHEAST FLOW.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 115 AM CDT MON MAY 20 2013
IT APPEARS THE LAST SURGE OF RAIN AND THUNDERSTORMS ARE MOVING
NORTH THROUGH THE TAF SITES AT THIS TIME AND FOR THE NEXT FEW
HOURS. MODERATE RAIN AND MVFR CIGS/VSBYS WILL CLEAR AS THE RAIN
MOVES OFF TO THE NORTH. A CLEARING TREND IS EXPECTED WITH VFR
EXPECTED FOR THE DAYLIGHT HOURS.
INSTABILITY WILL AGAIN BUILD OVER THE TAF SITES AND SET THE STAGE
FOR LATE AFTERNOON AND EVENING TSRA CHANCES. FOR NOW HAVE INCLUDED
A VCTS AND FUTURE FORECASTS CAN REFINE THE TIMING AT THE TAF
SITES. MONDAY AFTERNOON AND EVENING TSRA COVERAGE IS NOT EXPECTED
TO BE AS WIDESPREAD OR AFFECT THE TAF SITES AS LONG AS THE
ACTIVITY SUNDAY NIGHT.
&&
.HYDROLOGY...
ISSUED AT 341 AM CDT MON MAY 20 2013
MULTIPLE DAYS OF HEAVY RAIN ACROSS PORTIONS OF SOUTHEAST MINNESOTA
AND NORTHEAST IOWA HAS REALLY LOWERED THE THRESHOLD FOR FLOODING. A
STRIPE FROM MITCHELL COUNTY IA THROUGH MOWER...WESTERN FILLMORE AND
OLMSTED COUNTIES WERE ESPECIALLY HARD HIT FROM YESTERDAYS RAIN.
REPORT FROM MITCHELL COUNTY IA EMERGENCY MANAGER AT 330 AM WAS THAT
MOST MAIN ROADS ARE CLOSED DUE TO HIGH WATER AND MANY SIDE ROADS ARE
WASHED OUT. THUS...THE AREA THAT WAS PUT IN A FLASH FLOOD WATCH
YESTERDAY CANNOT HANDLE ANY MORE RAIN. SEE LATEST AREAL AND RIVER
FLOOD STATEMENTS FOR MORE INFORMATION.
ON A POSITIVE NOTE...THE DEEP MOISTURE THAT WAS PRESENT TO ALLOW THE
STORMS TO PRODUCE SUCH HEAVY RAIN IS SHIFTING OFF TO THE EAST.
ADDITIONALLY...EVEN THOUGH SOME THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON...THERE LOOKS TO BE ENOUGH UPPER LEVEL FLOW TO KEEP THEM
MOVING TO THE EAST. THUS...NOT ANTICIPATING ANY WIDESPREAD FLOODING.
WILL NEED TO KEEP THE FLASH FLOOD WATCH GOING...THOUGH...BECAUSE AS
MENTIONED EARLIER THE AREA HAS BEEN SO HARD HIT ANY RAIN WILL CAUSE
A PROBLEM.
ADDITIONAL RAINFALL IS POSSIBLE TUESDAY THROUGH WEDNESDAY
NIGHT...THOUGH TUESDAY IS TRENDING DRIER FOR SOUTHEAST MINNESOTA AND
NORTHEAST IOWA. HOPEFULLY THE DRIER PERIOD FROM TONIGHT THROUGH
TUESDAY WILL ALLOW THE FLOOD THREAT TO DIMINISH...THOUGH RIVER
FLOODING MAY TAKE A LITTLE LONGER TO END.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH THIS EVENING FOR MNZ079-086-087-094-
095.
IA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR IAZ008.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BAUMGARDT
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
111 AM CDT MON MAY 20 2013
.SHORT TERM...(TONIGHT AND MONDAY)
ISSUED AT 220 PM CDT SUN MAY 19 2013
UPPER LEVEL SHORTWAVE TROUGH SERVING AS ONE FOCUS FOR STORM
DEVELOPMENT EARLY THIS AFTERNOON. SKIES HAVE CLEARED AHEAD OF THE
SHORTWAVE...MOVING NORTH/NORTHEAST ACROSS IOWA...ALLOWING FOR RAPID
DESTABILIZATION OF THE ATMOSPHERE. MUCAPES PER LATEST RAP ANALYSIS
HAVE RISEN INTO THE 2-3 K J/KG RANGE...WITH 30-40 KTS OF EFFECTIVE
SHEAR. SUPERCELL DEVELOPMENT IS SUPPORTED. SEE A POTENTIAL FOR ALL
SEVERE WEATHER TYPES...WITH SUPERCELLS MORPHING INTO BOWING
SEGMENTS. THINK DAMAGING WINDS MIGHT BECOME THE GREATER THREAT LATER
THIS AFTERNOON AND EVENING.
HRRR SUGGESTS THERE WILL BE ANOTHER ROUND OF STRONG/SEVERE STORMS
COMING IN TOWARD 06S AS A SHORTWAVE PUSHES NORTHWARD ACROSS IOWA.
INSTABILITY WOULD DECREASE WITH THE LOSS OF DAYTIME HEATING...BUT
GFS/NAM STILL SUGGEST 1000+ J/KG OF MUCAPE AT 06Z...WITH 40+ KTS OF
0-6 KM SHEAR. PLENTY TO CONTINUE A SEVERE THREAT.
FOR MONDAY...ATMOSPHERE PROGGED TO RELOAD FOR THE AFTERNOON/EVENING
WITH MUCAPES UPWARDS OF 2500 J/KG AND MLCAPES UP TO 2000 J/KG. 0-6KM
WIND SHEAR CLIMBS TO 40-50 KTS BY 00Z TUE...SUPPORTIVE OF SUPERCELL
DEVELOPMENT. 0-1KM SHEAR IS 15-20 KTS. IF ALL THIS COMES TO
PASS...ATMOSPHERE WOULD BE RIPE FOR SEVERE WEATHER...WITH ROTATING
SUPERCELLS AND THE GAMBIT OF SEVERE THREATS. THE KEY IS THE
KICKER...AND THAT IS WHERE THE FORECAST CHALLENGE LIES. GFS/NAM
SUGGEST A SHORTWAVE TROUGH COULD LIFT OUT OF THE BASE OF THE UPPER
LEVEL TROUGH FOR THE AFTERNOON/EVENING...BUT ALSO POINT TO POSSIBLE
MCVS SPINNING INTO THE REGION. MEANWHILE...THERE WILL LIKELY BE LEFT
OVER SFC BOUNDARIES FROM CONVECTION TODAY/TONIGHT. WHERE THESE LIE
IS UNKNOWN. CONFIDENCE IS NOT HIGH IN WHERE/WHEN CONVECTION WILL
FIRE...BUT BELIEVE THE LATE AFTERNOON/EVENING WOULD BE THE FAVORED
TIME FOR A SEVERE THREAT...AND GENERALLY FROM CENTRAL WI INTO
NORTHEAST IA.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 220 PM CDT SUN MAY 19 2013
THE VIRTUALLY STATIONARY UPPER LEVEL LOW FINALLY STARTS TO MAKE ITS
WAY EAST OUT OF THE NORTHERN PLAINS TUE...PER LATEST GFS/NAM/EC. THE
LOW WEAKENS SOME AS IT SLIDES OVER THE UPPER MISSISSIPPI RIVER
VALLEY TUE NIGHT/WED. MAIN COLD FRONT WITH THIS SYSTEM LOOKS LIKE IT
WILL SLIP THROUGH WITH THE LOW AROUND WED...BUT MODELS KEEP
CONVECTION AT A MINIMUM AROUND IT. RATHER...THE PCPN FOCUS IS
WITH THE LOW LEVEL MOISTURE TRANSPORT...WHICH IS WELL EAST OF THE
COLD FRONT...WRAPPING NORTH/WEST OF THE LOW. SOME MODEL DISAGREEMENT
WITH HOW FAR SOUTH THE AREAS OF SHOWERS/ISOLD STORMS WOULD REACH
WED...WITH THE GFS MORE SOUTH THAN THE EC. IT REMAINS A MESSY
SCENARIO WITH CLARITY LACKING...BUT TRENDS FAVOR THE GREATER PCPN
CHANCES OVER THE NORTHERN 1/2 OF THE FORECAST AREA. WILL LEAN ON
MODEL CONSENSUS FOR THE CHANCES.
TURNING BACK TO TUE...MUCAPES BUILD TO 1500+ J/KG OVER THE EASTERN
1/2 OF THE FORECAST DURING THE AFTERNOON...WITH 0-6 KM SHEAR OF
30-40 KTS. SOME SUGGESTIONS IN THE GFS/NAM OF A PIECE OF UPPER LEVEL
ENERGY ROTATING AROUND THE LOW...WHICH COULD SERVE AS A FOCUS FOR
SHOWER/STORM DEVELOPMENT. ATMOSPHERE LOOKS GOOD FOR STORM PRODUCTION
IF A SPARK FOR CONVECTION IS THERE...WITH A SEVERE THREAT IN THE
EAST TUE AFTERNOON/EARLY EVENING. AGAIN...KEY HERE IS WHERE THE PCPN
FOCUSES WILL BE...INCLUDING ANY MESO SCALE BOUNDARIES AND/OR MCVS
LEFT FROM PREVIOUS CONVECTION.
BETTER AGREEMENT BETWEEN THE GFS AND ECMWF WITH PUSHING THAT
LINGERING LOW EAST/SOUTHEAST ON THU...ALLOWING AN UPPER LEVEL SFC
RIDGE/HIGH PRESSURE SYSTEM TO BUILD INTO THE REGION. SHOULD GET A
COUPLE DRIER DAYS AS A RESULT. HOWEVER...WARM/MOIST AIR ON THE
BACKSIDE OF THE HIGH COUPLED WITH A BIT OF UPPER LEVEL ENERGY COULD
RETURN SOME SHOWERS/STORMS TO THE REGION SAT-SUN.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 115 AM CDT MON MAY 20 2013
IT APPEARS THE LAST SURGE OF RAIN AND THUNDERSTORMS ARE MOVING
NORTH THROUGH THE TAF SITES AT THIS TIME AND FOR THE NEXT FEW
HOURS. MODERATE RAIN AND MVFR CIGS/VSBYS WILL CLEAR AS THE RAIN
MOVES OFF TO THE NORTH. A CLEARING TREND IS EXPECTED WITH VFR
EXPECTED FOR THE DAYLIGHT HOURS.
INSTABILITY WILL AGAIN BUILD OVER THE TAF SITES AND SET THE STAGE
FOR LATE AFTERNOON AND EVENING TSRA CHANCES. FOR NOW HAVE INCLUDED
A VCTS AND FUTURE FORECASTS CAN REFINE THE TIMING AT THE TAF
SITES. MONDAY AFTERNOON AND EVENING TSRA COVERAGE IS NOT EXPECTED
TO BE AS WIDESPREAD OR AFFECT THE TAF SITES AS LONG AS THE
ACTIVITY SUNDAY NIGHT.
&&
.HYDROLOGY...
ISSUED AT 800 PM CDT SUN MAY 19 2013
CONSIDERED AN EXPANSION TO THE FLASH FLOOD WATCH BUT BELIEVE THE
AREA IS WELL PLACED. WITH THE THUNDERSTORMS MOVING IN FROM
IOWA...THERE SHOULD BE A SCOURING EASTWARD AND END TO THE RAIN IN
NERN IA.
EXPECTING THE CEDAR RIVER TO RISE DOWNSTREAM OF OSAGE...CHARLES
CITY WILL SEE A LARGE JUMP IN THE NEXT 12 HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH THIS EVENING FOR MNZ079-086-087-094-
095.
IA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR IAZ008.
&&
$$
SHORT TERM...RIECK
LONG TERM....RIECK
AVIATION...BAUMGARDT
HYDROLOGY....RIECK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1126 PM CDT SUN MAY 19 2013
.UPDATE...
SEVERE SQUALL LINE AND TRAILING STRATIFORM REGION OVER ERN IA TO
MOVE ACROSS THE CWA BETWEEN 05Z-10Z. BOUNDARY LAYER WILL ONLY
STABILIZE IN THE LOWEST 1 KFT WITH ELEVATED CAPES OF 1000-2000
J/KG AVAILABLE FOR THE SQUALL LINE. THUS SVR WIND GUSTS WILL BE
CAPABLE AT GROUND LEVEL. AFTER CONVECTION ENDS AROUND
SUNRISE...THERE IS NO OBVIOUS TRIGGER FOR MON AND MON NT AS THE
LOW PRESSURE AREA WILL REMAIN OVER MN. THE WARM FRONT WILL LIFT
INTO CENTRAL WI WITH GOOD AMOUNTS OF CAPE AND VERY STRONG DEEP
LAYER SHEAR IN PLACE. 500 MB HEIGHTS WILL SLOWLY FALL THROUGH THIS
PERIOD WITH ONLY WEAK CAPPING. THUS EXPECT MORE STRONG TO SEVERE
THUNDERSTORMS BUT TIMING IS DIFFICULT...LATE MON AFTERNOON AND
NIGHT ARE BEST ESTIMATES. ALL MODES OF SEVERE WX ARE POSSIBLE.
&&
.AVIATION/06Z TAFS/...A STRONG TO SEVERE SQUALL LINE WILL AFFECT
SRN WI DURING THE OVERNIGHT. A BREAK IN CONVECTION WILL THEN LIKELY
OCCUR WITH MORE POSSIBLE LATE MON AFTERNOON AND NIGHT. CIGS AND
VSBYS WILL BE GREATLY REDUCED IN THE TSTORMS WITH SOME MVFR CIGS
AND VSBYS POSSIBLE IN THE STRATIFORM REGION OF THE SQUALL LINE
DURING THE OVERNIGHT. OTHERWISE...SCT-BKN040 CUMULUS TO CUMULUS
CONGESTUS WILL PREVAIL MON AND MON NT.
&&
.PREV DISCUSSION... /ISSUED 348 PM CDT SUN MAY 19 2013/
VERY SHORT TERM...TONIGHT AND MONDAY...FORECAST CONFIDENCE MEDIUM.
WATER VAPOR IMAGERY IS SHOWING A SERIES OF SHORT WAVES/VORT
MAXES/PERTURBATIONS LINING UP FROM THE PACIFIC NW TO NORTHERN NEW
MEXICO/PANHANDLE REGION OF TX/OK THAT WILL BE DIVING INTO AND AROUND
THE BASE OF A DEEPENING TROUGH OVER THE DAKOTAS. THESE WILL PROVIDE
THE TRIGGERING MECHANISM FOR SUCCESSIVE ROUNDS OF SHOWERS AND STORMS
OVER THE NEXT 24 TO 36 HOURS.
A CLUSTER OF THUNDERSTORMS OVER SOUTH CENTRAL WI PRODUCING WINDS OF
50 TO 60 MPH IS WEAKENING AS IT MOVES FURTHER EAST INTO THE MORE
CAPPED ENVIRONMENT. A COUPLE OF SITES HAVE REPORTED GUSTS OF 35 TO
45 MPH IN THE WAKE OF THIS SMALL TSTORM COMPLEX.
NOW KEEPING AN EYE ON CONVECTION IN CENTRAL IOWA THAT IS ASSOCIATED
WITH ANOTHER SHORTWAVE TROUGH EXTENDING SE FROM THE MCV NOW OVER SW
MN. HRRR AND WRF-ARW MODELS BRING THIS AREA OF CONVECTION INTO SOUTH
CENTRAL WI AROUND 23Z. SLIGHT STRENGTHENING OF THE LLJ OVER IL
DURING THIS TIME ALONG WITH 850MB WARM AIR ADVECTION AND THIS
SHORTWAVE TROUGH...ALONG WITH MIXED LAYER CAPE 1000-1300 J/KG AND
SHEAR PARAMETERS /0-3KM SHEAR AROUND 20 KNOTS WILL BE FAVORABLE TO
SUPPORT ONGOING SURFACE-BASED CONVECTION LATE THIS AFTERNOON...AND
MORE ELEVATED CONVECTION AS IT MOVES TOWARD SOUTHEAST WI. THE SEVERE
POTENTIAL IS THERE FOR HAIL AND STRONG WINDS.
THERE IS ANOTHER SHORTWAVE ON THE HEELS OF THIS ONE...CURRENTLY OVER
SOUTHWEST IOWA. MESOSCALE MODELS SHOW THIS ONE TO BE THE SOURCE OF
AN OVERNIGHT CONVECTIVE COMPLEX...LIKELY HITTING SOUTHERN WI BETWEEN
06Z TO 12Z MONDAY...BUT EXACT TIMING IS DEBATABLE. CORFIDI VECTORS
WEAKEN OVER SOUTHERN WI DURING THIS TIME...SUGGESTING SLOW-MOVING
THUNDERSTORMS AND THE HEAVY RAIN/LOCALIZED FLOODING POTENTIAL.
SEVERE HAIL AND WINDS WILL ALSO BE POSSIBLE WITH THIS ROUND.
THEN IT WILL BE A MATTER OF HOW QUICKLY THE CONVECTIVE DEBRIS CAN
CLEAR IN ORDER FOR THE ATMOSPHERE TO RE-DESTABILIZE IN SOUTHERN WI.
IT WILL ALSO DEPEND ON WHERE THE EFFECTIVE WARM FRONT SETS
UP...WHICH WILL BE BASED ON OVERNIGHT CONVECTION. MODELS ARE
SUGGESTING THE WARM FRONT WILL BE UP IN NORTHERN WI BY MONDAY
AFTERNOON...BUT SOMETIMES MODELS TEND TO MOVE IT TOO FAR TO THE
NORTH. WILL NEED TO MONITOR THIS TREND.
THE CRAVEN-WIEDENFELD AGGREGATE SEVERE PARAMETER /CWASP/ IS
BASICALLY A SCORING/RATING SYSTEM FOR SEVERE WEATHER PARAMETERS. A
VALUE OVER 80 CORRESPONDS WITH A GOOD CHANCE FOR SEVERE WEATHER IN
THAT AREA. WE CONTINUE TO SEE VALUES IN THE 80S OVER SOUTHERN WI 18Z
MONDAY TO 06Z TUESDAY. IF THE ATMOSPHERE CAN RECOVER FROM ANY
OVERNIGHT CONVECTION IN TIME...THEN SURFACE-BASED SEVERE STORMS WILL
BE LIKELY. LARGE HAIL...STRONG WINDS AND TORNADOES WOULD ALL BE
POSSIBLE. STAY TUNED TO THE FORECAST.
SHORT TERM...MONDAY NIGHT THROUGH WEDNESDAY.
MONDAY NIGHT AND TUESDAY...FORECAST CONFIDENCE MEDIUM.
TIMING CONTINUES TO BE EVERYTHING WITH THE SERIES OF SHORT
WAVES/VORT MAXES/PERTURBATIONS...ROUNDING THE BASE OF THE CLOSED LOW
CENTERED NEAR THE DAKOTAS/MINNESOTA BORDER AND LIFTING NORTH
THROUGH THE REGION...THAT WILL BE THE TRIGGERING MECHANISMS FOR
SHOWERS AND THUNDERSTORMS.
ONGOING CONVECTION WILL BE TAPERING OFF...WITH INCREASING
CONVERGENCE AHEAD OF NEXT 850 MB SPEED MAX ASSOCIATED WITH ANOTHER
SHORT WAVE APPROACHING BETWEEN 06Z AND 12Z TUESDAY. WHILE BETTER
POTENTIAL FOR SEVERE APPEARS TIED TO STRONGER FORCING FOCUSING TO
THE SOUTHWEST...STILL LIKELY TO SEE THUNDER...WITH ELEVATED CAPE
BETWEEN 600 AND 1000 J/KG.
CWASP FOR ALL MODELS SHIFTS HIGHER PERCENTAGES TO THE SOUTH FOR
TUESDAY...BUT GFS/GEM AND TO SOME EXTENT THE ECMWF STILL HAVE HIGH
ENOUGH VALUES TO CONTINUE PROBABILITY OF SEVERE INTO TUESDAY.
TUESDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE MEDIUM.
THREAT FOR WIDESPREAD THUNDERSTORMS TAPERS OFF OVERNIGHT INTO
WEDNESDAY AS FOCUS OF LOW-LEVEL JET SHIFTS SOUTHEAST AS CLOSED
SYSTEM SHIFTS TO THE EAST TOWARD WISCONSIN...AND CONVECTIVE
PARAMETERS DIMINISH. A BLENDED SOLUTION TO BALANCE TIMING
DIFFERENCES KEEPS LIKELY THUNDER IN THE EASTERN CWA...MAINLY IN THE
MORNING...WITH CHANCES FOR SHOWERS IN THE WEST.
LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY. FORECAST CONFIDENCE
ALL THE MODELS SHIFT THE SURFACE LOW FAR ENOUGH EAST BY WEDNESDAY
NIGHT FOR COOL NORTHERLY WINDS TO PUSH IN. WILL HAVE TO KEEP CHANCES
OF SHOWERS IN THE FORECAST UNTIL 500 MB TROUGH CLEARS SOUTHERN
WISCONSIN THURSDAY EVENING. RIDGING BUILDS IN WITH OMEGA BLOCK
SETTING UP BRINGING DRY WEATHER AND BELOW NORMAL TEMPERATURES INTO
SATURDAY. THE CHANCE FOR SHOWERS AND THUNDERSTORMS RETURNS FOR
SATURDAY NIGHT AND SUNDAY WITH WARM AIR TRYING TO PUSH INTO THE
WESTERN GREAT LAKES AS EASTERN LOW SHIFTS AWAY AND SHORT WAVE
ENERGY EJECTING FROM WESTERN TROUGH BREAKS DOWN RIDGE.
AVIATION/00Z TAFS/...
THUNDERSTORMS IN SOUTH CENTRAL WI WILL DRIFT NORTHEAST AND
DISSIPATE LATE THIS AFTERNOON. ANOTHER BROKEN LINE OF
THUNDERSTORMS OVER NORTHEAST IOWA ARE EXPECTED TO TRACK INTO SOUTH
CENTRAL WI AROUND 23Z PER MESOSCALE MODELS. THEN ANOTHER ROUND OF
CONVECTION IS LOOKING MORE LIKELY FOR AFTER MIDNIGHT
TONIGHT...WHICH WOULD PROBABLY CLEAR SOUTHEAST WI EARLY MONDAY
MORNING. THUNDERSTORMS WILL HAVE THE POTENTIAL FOR STRONG WINDS
AND HAIL TONIGHT.
BEST CHANCE FOR SEVERE THUNDERSTORMS WITH A WIND/HAIL/TORNADO THREAT
IS LOOKING LIKE MONDAY AFTERNOON. SEE THE DISCUSSION ABOVE FOR
DETAILS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...GEHRING
TONIGHT/MONDAY AND AVIATION/MARINE...MRC
MONDAY NIGHT THROUGH SUNDAY...REM
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
1039 AM CDT MON MAY 20 2013
.UPDATE...
MADE SOME CHANGES TO THE FORECAST FOR TODAY. A LOOK AT THE MORNING
SOUNDING REVEALS A VERY UNSTABLE ATMOSPHERE WITH A RATHER
SIGNIFICANT CAP AROUND 850 MB. IN SPITE OF THAT THERE IS ABUNDANT
MOISTURE PRESENT AND I FELT IT WOULD BE PRUDENT TO INTRODUCE SOME
RELATIVELY LOW POPS FURTHER TO THE SOUTH ACROSS THE CWA TODAY. IN
ADDITION...CLOUD COVER IS A BIT MORE EXTENSIVE THAN PREVIOUSLY
FORECAST AND IT LOOKS LIKE WE WILL CONTINUE TO HAVE MORE THAN
FORECAST FOR THE REST OF THE DAY...SO I UPPED THOSE VALUES AS WELL.
GETTING BACK TO THE ISSUE OF THE UNSTABLE SOUNDING...THE MODELS
ARE HAVING SOME DIFFICULTIES WITH HOW TO HANDLE THE TIMING OF
STORMS THIS AFTERNOON AND TONIGHT. THE ATMOSPHERE IS QUITE
UNSTABLE...SFC BASED CAPE VALUES ARE ABOVE 3000 J/KG IN CENTRAL
ARKANSAS THIS MORNING AND THE HODOGRAPH IS A BIT OMINOUS. I AM
CONCERNED ABOUT THE POTENTIAL FOR THE DEVELOPMENT OF DISCRETE
SUPERCELLS LATER THIS AFTERNOON AND EVENING ACROSS THE NWRN
PORTIONS OF THE FORECAST AREA. WE WILL BE CONDUCTING A SPECIAL
SOUNDING AT 18Z TODAY TO ASSESS HOW THINGS HAVE CHANGED BY MIDDAY.
CONVECTION THAT WAS OCCURRING ACROSS THE NORTHERN PART OF THE
STATE EARLIER THIS MORNING HAS FIZZLED OUT AND WITH THE EXCEPTION
OF CONVECTION ACROSS WESTERN MO...NOT MUCH ELSE IS HAPPENING THIS
MORNING. I CANT HELP BUT WONDER IF UPPER LEVEL JET DYNAMICS ARE
PLAYING A SUPRESSING ROLE THIS MORNING AS SOME MODELS ARE IMPLYING
A JET MAX EXITING OVER NW MO THIS MORNING WITH ANOTHER SPEED MAX
OVER NRN OK THIS MORNING SWINGING AROUND. IF THAT HOLDS UP THE LID
COULD START TO COME OFF THE CONVECTION BY EARLY TO MID AFTERNOON
ACROSS THE NW. 53
&&
.PREV DISCUSSION... /ISSUED 620 AM CDT MON MAY 20 2013/
DISCUSSION...
UPDATED TO INCLUDE THE 12Z AVIATION DISCUSSION BELOW...
AVIATION...
A LINE OF SHRA/TSRA IS EXTENDING FROM MO INTO NORTH CENTRAL AR
THIS MORNING...WITH VCTS CONTINUING IN THE TAF FOR THE NRN SITES
THIS MORNING. OTHERWISE...SOME SITES WERE SEEING SOME MVFR
CIGS...WHICH SHOULD IMPROVE TO VFR LEVELS OUTSIDE ANY PRECIP
ACTIVITY LATER THIS MORNING. ALSO...SOME AREAS EARLY IN THE PERIOD
COULD SEE A BIT OF LOW END LLWS...BUT SHOULD IMPROVE AS SFC WINDS
INCREASE LATER THIS MORNING. BREEZY SRLY WINDS WILL BE SEEN TROUGH
THIS AFTERNOON AND EARLY EVENING AS SFC PRESSURE GRADIENT REMAINS
FAIRLY TIGHT ACROSS THE REGION. HAVE MENTIONED VCTS ACROSS THE NRN
SITES THROUGH THIS AFTERNOON AS ADDITIONAL TSRA COULD DEVELOP THIS
AFTERNOON. THIS EVENING AND INTO TUE MORNING...THE POTENTIAL FOR
SHRA/TSRA WILL SPREAD FURTHER SOUTH AND EAST...WITH PROB30 OR VCTS
MENTIONED FOR TSRA POTENTIAL DURING THIS PERIOD OF THE TAF. SOME
MVFR OR LOWER CONDITIONS COULD BE SEEN UNDER THE PRECIP ACTIVITY.
PREV DISCUSSION... /ISSUED 410 AM CDT MON MAY 20 2013/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
STORMS FORMED OVER NORTHEAST OKLAHOMA LATE SUNDAY EVENING...AND
MOVED NORTHEAST INTO SOUTHERN MISSOURI OVERNIGHT. HOWEVER...SHOWERS
HAVE RECENTLY DEVELOPED ALONG THE SOUTHERN EDGE AND ARE MOVING INTO
NORTHERN ARKANSAS. HAVE KEPT SMALL RAIN CHANCES ACROSS THE NORTH
THROUGH THE MORNING HOURS...AS MUCH OF THIS ACTIVITY WILL DISSIPATE
BEFORE NOON.
QUESTION FOR THIS AFTERNOON WILL BE IF ANY DEVELOPMENT OCCURS ON ANY
LINGERING BOUNDARIES LEFT OVER FROM THE OVERNIGHT ACTIVITY. THE NAM
AND NOW THE HRRR IS PICKING UP ON THIS...AHEAD OF ACTIVITY
DEVELOPING OFF LOW LEVEL JET AROUND SUNSET. THIS WILL HAVE TO BE
MONITORED CLOSELY...BECAUSE IF ANY CELL IS DISCRETE...SEVERE WEATHER
WILL BE MAXIMIZED.
THIS EVENING...STORMS WILL FORM ACROSS EASTERN OKLAHOMA INTO
SOUTHERN MISSOURI...AS FRONT INTERACTS WITH LOW LEVEL JET. THE
STORMS WILL SLOWLY MOVE EAST DURING THE LATE EVENING INTO THE
OVERNIGHT HOURS...WITH STRONG TO SEVERE STORMS POSSIBLE. ALSO...WITH
THE SLOW MOTION AND COPIOUS AMOUNTS OF MOISTURE...HEAVY RAINFALL IS
POSSIBLE...ESPECIALLY ACROSS THE NORTHWEST HALF OF THE STATE TONIGHT.
THE FRONT WILL PROGRESS INTO THE STATE TUESDAY...WITH SEVERE
POTENTIAL CONTINUING. HOWEVER...TORNADIC POTENTIAL WILL NOT BE AS
GREAT DUE TO LESSENING SHEAR. FLOODING REMAINS A CONCERN FOR
TUESDAY...AS SEVERAL ROUNDS OF THUNDERSTORMS WILL MOVE ACROSS THE
AREA.
THE RAINFALL WILL BEGIN TO MOVE SOUTHEAST LATE TUESDAY INTO TUESDAY
NIGHT...WITH MUCH OF THE ACTIVITY CONFINED TO THE SOUTHEAST HALF OF
THE STATE WEDNESDAY. HOWEVER...THE FRONT WILL MEANDER AROUND THE
AREA THROUGH THE END OF THE SHORT TERM...WITH SMALL RAIN CHANCES
CONTINUING.
LONG TERM...FRIDAY THROUGH SUNDAY
COLD FRONT WILL HAVE PUSHED INTO THE STATE FROM THE NE AT THE START
OF THE LONG TERM PERIOD...STALLING ACROSS THE STATE FROM NW TO SE.
MENTION SLIGHT CHANCE POPS WITH THIS FRONT OVER THE STATE FOR
FRI...BUT AN UPPER RIDGE TO THE WEST WILL BEGIN TO SHIFT EAST OVER
THE SRN PLAINS AND SRN MS RIVER VALLEY REGION INTO THIS WEEKEND. AS
A RESULT OF THE RIDGING ALOFT...DECREASE POPS INTO THE WEEKEND...AS
WELL AS INCREASING TEMPS ABOVE NORMAL BY LATE IN THE FORECAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 85 69 80 65 / 20 50 60 80
CAMDEN AR 89 70 87 67 / 10 20 50 70
HARRISON AR 82 66 78 60 / 40 80 70 60
HOT SPRINGS AR 88 71 84 67 / 20 40 60 70
LITTLE ROCK AR 88 70 84 68 / 20 40 60 70
MONTICELLO AR 90 72 88 69 / 10 20 40 60
MOUNT IDA AR 87 70 83 64 / 20 50 60 70
MOUNTAIN HOME AR 83 67 77 61 / 30 80 60 70
NEWPORT AR 87 70 82 67 / 20 40 60 80
PINE BLUFF AR 89 71 86 69 / 10 20 50 70
RUSSELLVILLE AR 85 68 80 63 / 20 60 60 70
SEARCY AR 87 69 82 66 / 20 40 60 70
STUTTGART AR 89 71 85 68 / 10 30 50 70
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...99
AREA FORECAST DISCUSSION...UPDATED
NWS LITTLE ROCK AR
620 AM CDT MON MAY 20 2013
.DISCUSSION...
UPDATED TO INCLUDE THE 12Z AVIATION DISCUSSION BELOW...
&&
.AVIATION...
A LINE OF SHRA/TSRA IS EXTENDING FROM MO INTO NORTH CENTRAL AR
THIS MORNING...WITH VCTS CONTINUING IN THE TAF FOR THE NRN SITES
THIS MORNING. OTHERWISE...SOME SITES WERE SEEING SOME MVFR
CIGS...WHICH SHOULD IMPROVE TO VFR LEVELS OUTSIDE ANY PRECIP
ACTIVITY LATER THIS MORNING. ALSO...SOME AREAS EARLY IN THE PERIOD
COULD SEE A BIT OF LOW END LLWS...BUT SHOULD IMPROVE AS SFC WINDS
INCREASE LATER THIS MORNING. BREEZY SRLY WINDS WILL BE SEEN TROUGH
THIS AFTERNOON AND EARLY EVENING AS SFC PRESSURE GRADIENT REMAINS
FAIRLY TIGHT ACROSS THE REGION. HAVE MENTIONED VCTS ACROSS THE NRN
SITES THROUGH THIS AFTERNOON AS ADDITIONAL TSRA COULD DEVELOP THIS
AFTERNOON. THIS EVENING AND INTO TUE MORNING...THE POTENTIAL FOR
SHRA/TSRA WILL SPREAD FURTHER SOUTH AND EAST...WITH PROB30 OR VCTS
MENTIONED FOR TSRA POTENTIAL DURING THIS PERIOD OF THE TAF. SOME
MVFR OR LOWER CONDITIONS COULD BE SEEN UNDER THE PRECIP ACTIVITY.
&&
.PREV DISCUSSION... /ISSUED 410 AM CDT MON MAY 20 2013/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
STORMS FORMED OVER NORTHEAST OKLAHOMA LATE SUNDAY EVENING...AND
MOVED NORTHEAST INTO SOUTHERN MISSOURI OVERNIGHT. HOWEVER...SHOWERS
HAVE RECENTLY DEVELOPED ALONG THE SOUTHERN EDGE AND ARE MOVING INTO
NORTHERN ARKANSAS. HAVE KEPT SMALL RAIN CHANCES ACROSS THE NORTH
THROUGH THE MORNING HOURS...AS MUCH OF THIS ACTIVITY WILL DISSIPATE
BEFORE NOON.
QUESTION FOR THIS AFTERNOON WILL BE IF ANY DEVELOPMENT OCCURS ON ANY
LINGERING BOUNDARIES LEFT OVER FROM THE OVERNIGHT ACTIVITY. THE NAM
AND NOW THE HRRR IS PICKING UP ON THIS...AHEAD OF ACTIVITY
DEVELOPING OFF LOW LEVEL JET AROUND SUNSET. THIS WILL HAVE TO BE
MONITORED CLOSELY...BECAUSE IF ANY CELL IS DISCRETE...SEVERE WEATHER
WILL BE MAXIMIZED.
THIS EVENING...STORMS WILL FORM ACROSS EASTERN OKLAHOMA INTO
SOUTHERN MISSOURI...AS FRONT INTERACTS WITH LOW LEVEL JET. THE
STORMS WILL SLOWLY MOVE EAST DURING THE LATE EVENING INTO THE
OVERNIGHT HOURS...WITH STRONG TO SEVERE STORMS POSSIBLE. ALSO...WITH
THE SLOW MOTION AND COPIOUS AMOUNTS OF MOISTURE...HEAVY RAINFALL IS
POSSIBLE...ESPECIALLY ACROSS THE NORTHWEST HALF OF THE STATE TONIGHT.
THE FRONT WILL PROGRESS INTO THE STATE TUESDAY...WITH SEVERE
POTENTIAL CONTINUING. HOWEVER...TORNADIC POTENTIAL WILL NOT BE AS
GREAT DUE TO LESSENING SHEAR. FLOODING REMAINS A CONCERN FOR
TUESDAY...AS SEVERAL ROUNDS OF THUNDERSTORMS WILL MOVE ACROSS THE
AREA.
THE RAINFALL WILL BEGIN TO MOVE SOUTHEAST LATE TUESDAY INTO TUESDAY
NIGHT...WITH MUCH OF THE ACTIVITY CONFINED TO THE SOUTHEAST HALF OF
THE STATE WEDNESDAY. HOWEVER...THE FRONT WILL MEANDER AROUND THE
AREA THROUGH THE END OF THE SHORT TERM...WITH SMALL RAIN CHANCES
CONTINUING.
LONG TERM...FRIDAY THROUGH SUNDAY
COLD FRONT WILL HAVE PUSHED INTO THE STATE FROM THE NE AT THE START
OF THE LONG TERM PERIOD...STALLING ACROSS THE STATE FROM NW TO SE.
MENTION SLIGHT CHANCE POPS WITH THIS FRONT OVER THE STATE FOR
FRI...BUT AN UPPER RIDGE TO THE WEST WILL BEGIN TO SHIFT EAST OVER
THE SRN PLAINS AND SRN MS RIVER VALLEY REGION INTO THIS WEEKEND. AS
A RESULT OF THE RIDGING ALOFT...DECREASE POPS INTO THE WEEKEND...AS
WELL AS INCREASING TEMPS ABOVE NORMAL BY LATE IN THE FORECAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 85 69 80 65 / 20 50 70 70
CAMDEN AR 89 70 87 67 / 10 20 40 70
HARRISON AR 81 66 78 60 / 30 80 70 60
HOT SPRINGS AR 88 71 84 67 / 10 30 60 70
LITTLE ROCK AR 88 70 84 68 / 10 30 60 70
MONTICELLO AR 90 72 88 69 / 10 10 40 70
MOUNT IDA AR 87 70 83 64 / 20 40 60 70
MOUNTAIN HOME AR 82 67 77 61 / 30 80 70 70
NEWPORT AR 86 70 82 67 / 10 40 60 80
PINE BLUFF AR 89 71 86 69 / 10 20 50 70
RUSSELLVILLE AR 85 68 80 63 / 20 50 70 70
SEARCY AR 87 69 82 66 / 10 30 60 70
STUTTGART AR 88 71 85 68 / 10 20 50 70
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...62
AREA FORECAST DISCUSSION
NWS TAUNTON MA
701 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WARM FRONT LIFTING THROUGH THE REGION WILL BRING A FEW SHOWERS
OR THUNDERSTORMS TODAY AS IT HEADS INTO CENTRAL NEW ENGLAND. THE
FRONT WILL DROP BACK SOUTH ON TUESDAY RESULTING IN BRIEFLY COOLER
WEATHER...BEFORE WARM AND HUMID CONDITIONS RETURN WEDNESDAY AND
THURSDAY WITH SCATTERED SHOWERS AND THUNDERSTORMS. IT WILL TURN
COOLER AND LESS HUMID NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
7 AM UPDATE...
WARM FRONT PROGRESSING NORTHWARD AND WILL MOVE THROUGH THE REGION
BY LATE MORNING OR MIDDAY AT THE LATEST. TEMPS ALREADY OFF TO A
MILD START WITH READINGS IN THE U50S AND L60S AT 7 AM. TEMPS WILL
SOAR THROUGHT THE 70S TO AROUND 80 THIS AFTERNOON AWAY FROM THE
SHORE. ONCE BOUNDARY LIFTS NORTH OF THE AREA NOT MUCH OF A FOCUS
FOR CONVECTION. IN ADDITION 0-6KM WIND FIELD DROPS BELOW 30 KT
THIS AFTERNOON. THUS ANY CONVECTION WOULD NOT BE ORGANIZED OR
WIDESPREAD. PREVIOUS FORECAST CAPTURES THIS WELL SO NO MAJOR
CHANGES WITH THIS UPDATE.
===================================================================
LAST OF SHOWERS WERE EXITING CAPE COD AND ISLANDS EARLY THIS
MORNING. CLOUDS REMAIN LOCKED IN WITH PATCHY FOG AND DRIZZLE...
WHICH WILL PERSIST THROUGH MID MORNING. THEREAFTER MODEL CROSS
SECTIONS SHOW SOME DRYING THROUGH COLUMN AS WEAK WARM FRONT LIFTS
TO OUR N. THIS SHOULD ALLOW FOR BREAKS OF SUNSHINE TO DEVELOP
LATER THIS MORNING AND THIS AFTERNOON FOR MUCH OF SOUTHERN NEW
ENGLAND. EXCEPTION WILL BE NEAR S COAST...CAPE COD AND ISLANDS
WHERE MARINE LAYER SHOULD HOLD STRONG GIVEN SW FLOW.
POTENTIAL FOR CONVECTION THIS AFTERNOON IS LIMITED BY LACK OF
INSTABILITY AS SB CAPES ONLY FORECAST TO BE AS HIGH AS 500
J/KG...WEAK MID LEVEL LAPSE RATES OF LESS THAN 5C/KM...AND
MARGINAL 0-6KM SHEAR OF 30KT. THAT SAID WE DO EXPECT TO SEE AT
LEAST WIDELY SCATTERED SHOWERS/STORMS DEVELOP ACROSS INTERIOR.
MAINTAINED CHANCE POPS AWAY FROM S COAST...ALTHOUGH BEST CHANCE
LOOKS TO BE ACROSS SW NH AND NW MA. HRRR SHOWS SCATTERED ACTIVITY
DEVELOPING IN THOSE AREAS AFTER 18Z.
CERTAINLY LOOKS LIKE A WARMER AND SOMEWHAT MORE HUMID DAY WITH
HIGHS RANGING FROM 60S ALONG S COAST TO 70S AND LOWER 80S
ELSEWHERE. USED A BLEND OF NAM/GFS MOS.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM TUESDAY/...
WARM FRONT STALLS ACROSS CENTRAL NEW ENGLAND TONIGHT. THIS WILL
MAINTAIN LIGHT S/SW FLOW ACROSS REGION AND WITH PLENTY OF LOW
LEVEL MOISTURE...CONFIDENCE IS HIGH ON SEEING LOW CLOUDS/FOG AND
POSSIBLY DRIZZLE SPREAD INLAND FROM COAST. POTENTIAL IS THERE FOR
AREAS OF DENSE FOG...ESPECIALLY AROUND CAPE COD AND ISLANDS.
OTHERWISE NO SIGNIFICANT RAINFALL IS EXPECTED AS BEST DYNAMICS
STAY TO OUR N AND W. RELATIVELY MILD NIGHT WITH LOWS HOLDING IN
50S/LOWER 60S...WHICH IS CLOSER TO NAM MOS.
WEAK UPPER RIDGE BUILDING ACROSS NEW YORK STATE WILL FORCE FRONT
BACK SOUTHWARD TUE AS A BACKDOOR COLD FRONT. MODELS IN GOOD
AGREEMENT IN DROPPING FRONT THROUGH TUE AFTERNOON...BUT GFS SEEMS
TO OVERDO CONVECTION RIDING E ALONG BOUNDARY FROM GREAT LAKES. NAM
SEEMS MUCH MORE REASONABLE IN STABILIZING AIRMASS OVER SOUTHERN
NEW ENGLAND AS FLOW TURNS MORE E/SE AND FOCUSES ANY CONVECTION TO
OUR W/N WHERE IT BECOMES MORE UNSTABLE. WE ARE NOT THINKING WE
WILL SEE MUCH IN WAY OF SHOWERS/STORMS DEVELOP...ALTHOUGH IT IS
POSSIBLE A FEW SHOWERS MAKE IT INTO WESTERN NEW ENGLAND BY END OF
DAY.
SHOULD BE WIDE RANGE IN TEMPERATURES TUE DUE TO ONSHORE FLOW...
FROM LOWER 60S ALONG E MA COASTLINE INCLUDING CAPE COD TO UPPER
70S ACROSS CT RIVER VALLEY. LEANED MORE TOWARD NAM MOS WHICH
CAPTURES THIS WELL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGHLIGHTS...
* WARM AND MUGGY WED/THU THEN TURNING COOLER AND LESS HUMID FRI
* SCATTERED SHOWERS AND THUNDERSTORMS WED AND THU
* DRY BUT COOLER THAN NORMAL FOR MEMORIAL DAY WEEKEND
GOOD OVERALL AGREEMENT ON THE LARGE SCALE FLOW INCLUDING FRONTAL
POSITIONS FROM THE 12Z/19 GEFS AND ECENS. BOTH OF THESE ENSEMBLE
DATA SETS HAVE A BACKDOOR FRONT SAGGING SOUTHWARD THROUGH THE
SOUTHERN NEW ENGLAND TUE NIGHT THEN LIFTING NORTH OF THE REGION WED
AND THU WITH TRUE WARM SECTOR OVERSPREADING THE AREA. BOTH ENSEMBLES
OFFER +16C AIRMASS AT 850 MB AND +20C AT 925 MB OVER THE REGION
WED. THUS POTENTIAL FOR TEMPS TO SOAR INTO THE 80S BOTH DAYS IF
SUNSHINE DEVELOPS. IT WILL BE MUGGY AS WELL WITH DEW PTS IN THE 60S.
THIS WILL RESULT IN WARM NIGHTS /WED AND THU/ ALONG WITH PATCHY FOG.
SCATTERED SHOWERS AND THUNDERSTORMS LIKELY BOTH WED AND THU GIVEN
WARM SECTOR OVER THE AREA BOTH DAYS. ALSO MODELS IN GOOD AGREEMENT
ON CONVECTION ALONG OR NEAR THE WARM FRONT TUE EVENING/NIGHT.
CONVECTION WILL BE MORE WIDESPREAD DURING PEAK HEATING HOURS OF THE
AFTERNOON AND LINGERING INTO THE EARLY EVENING BOTH DAYS. ENSEMBLES
SUGGEST INSTABILITY GREATER WED (MEAN CAPE ABOUT 1000J/KG) THAN THU.
HOWEVER APPROACHING COLD FRONT WILL YIELD GREATER FRONTAL
CONVERGENCE THU ALONG WITH STRONGER JET DYNAMICS /0-6KM DEEP LAYER
SHEAR/...SO CONVECTION MAY BE MORE ORGANIZED/NUMEROUS THU THAN WED.
IN ADDITION GEFS SUGGEST INSTABILITY RIDGE ACROSS NY/PA AND NJ.
THEREFORE WESTERN NEW ENGLAND HAS GREATEST RISK FOR STRONG TO
PERHAPS SEVERE TSTMS WED AND THU. GIVEN INSTABILITY AND PWATS OF +1
TO +2 STD HEAVY DOWNPOURS ARE POSSIBLE WITH ANY CONVECTION.
GOOD MODEL AGREEMENT THAT FRONTAL PASSAGE WILL OCCUR SOMETIME LATE
THU OR FRI. 00Z GFS SLOWER WITH FROPA AS IT DEVELOPS A WAVE ALONG
THE FRONT. AT THIS TIME RANGE PREFER NOT TO CHASE A SINGLE
DETERMINISTIC SOLUTION SO WILL FOLLOW PRES PATTERN FROM GEFS AND
ECENS. THIS SUGGEST FRI WILL BE OUR TRANSITION DAY FROM WARM AND
MUGGY TO A DRY...MUCH COOLER AND LESS HUMID AIRMASS FOR MEMORIAL DAY
WEEKEND. IN FACT BY SAT BOTH GEFS AND ECENS HAVE A 1030MB HIGH
SETTLING OVER THE GREAT LAKES WITH CORE OF THIS ANOMALOUS COOL
AIRMASS /850 TEMPS 0C TO +2C/ ACROSS NORTHERN MA/SOUTHWEST NH...THEN
SLOWLY MODERATING BY MON. HENCE MILD DAYS BUT COOL NIGHTS. IN FACT
THERE COULD BE SOME PATCHY FROST ACROSS NORTHWEST MA INTO SOUTHWEST
NH WITH TEMPS DIPPING INTO THE MU30S SAT AND SUN MORNING!
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
7 AM UPDATE...
NO CHANGE TO PREVIOUS FORECAST. FORECAST REMAINS ON TRACK.
MODERATE CONFIDENCE THROUGH TUE.
WIDESPREAD IFR/LIFR THROUGH 12Z IN LOW CLOUDS/FOG/DRIZZLE. GRADUAL
IMPROVEMENT TO MVFR EXPECTED 12Z-15Z AND EVENTUALLY VFR BY 18Z
EXCEPT AROUND CAPE COD AND ISLANDS WHERE IFR LIKELY TO PERSIST ALL
DAY. SCT SHOWERS WILL REFORM ACROSS INTERIOR AFTER 18Z WITH
ISOLATED THUNDER ALSO POSSIBLE.
SHOULD SEE RAPID DETERIORATION THIS EVENING TO IFR/LIFR 23Z-03Z
AS LOW CLOUDS/FOG/DRIZZLE RETURN IN LIGHT ONSHORE FLOW. WILL BE
HARDER FOR IFR TO ERODE TUE WITH PERSISTENT E/SE WIND...BUT EXPECT
ALL BUT CAPE/ISLANDS TO IMPROVE TO MVFR CIGS BY 18Z.
KBOS TERMINAL...MODERATE CONFIDENCE. CONFIDENT ON TIMING OF
IMPROVEMENT THIS MORNING...BUT CIGS MAY ONLY LIFT TO 025 THROUGH
18Z.
KBDL TERMINAL...MODERATE CONFIDENCE. MAY BE 2-3 HOURS TOO FAST ON
IMPROVEMENT TO MVFR CIGS THIS MORNING.
OUTLOOK...TUESDAY NIGHT THROUGH FRIDAY...
TUESDAY THROUGH THURSDAY NIGHT...MODERATE CONFIDENCE. VERY
UNSETTLED PATTERN WITH VARIABILITY BETWEEN VFR CONDITIONS AND
MVFR/IFR CONDITIONS IN SHRA/TSRA/FOG. A FEW STRONG TO SEVERE TSTMS
POSSIBLE WED AND THU.
FRIDAY...MODERATE CONFIDENCE. CONDITIONS SHOULD IMPROVE ALONG WITH
A WIND SHIFT FROM WEST TO EAST AS COLD FRONT MOVES THROUGH REGION.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
HIGH CONFIDENCE THROUGH TUE.
WARM FRONT LIFTS N OF COASTAL WATERS TODAY AND STALLS OVER CENTRAL
NEW ENGLAND. LIGHT S/SW FLOW DEVELOPS ACROSS WATERS BUT SEAS
SLOWLY BUILD IN SOUTHERLY SWELL...MOST NOTABLY ACROSS S COASTAL
WATERS WHERE SCA REMAINS POSTED. ALTHOUGH SW FLOW IS MODEST AT
BEST IT SHOULD STILL CREATE STEEP WAVES ON BUZZARDS BAY AND
VINEYARD SOUND DURING OUTGOING TIDE THIS AFTERNOON...SO MAINTAINED
SCA FOR THOSE AREAS AS WELL.
EXPECT AREAS OF DENSE FOG TONIGHT INTO TUE WITH PERSISTENT SW
FLOW...ESPECIALLY AROUND CAPE COD AND ISLANDS. FRONT DROPS BACK S
TUE AND SHIFTS WINDS TO E/SE...SO VSBYS SHOULD IMPROVE TUE
AFTERNOON. SEAS SHOULD BEGIN TO SUBSIDE AS WELL DUE TO DECAYING
SOUTHERLY SWELL.
OUTLOOK...TUESDAY THROUGH FRIDAY...
TUESDAY NIGHT... BACKDOOR FRONT SLIPS ACROSS THE AREA WITH NE WINDS
LIKELY OVER THE NORTHERN WATERS AND SW WINDS ACROSS SOUTHERN WATERS.
RAIN AND FOG WILL REDUCE VSBY. MODEST WIND AT BEST WITH MARGINAL
SWELL.
WED AND THU... WARM FRONT LIFTS NORTH OF THE AREA WITH MODEST SSW
WINDS DEVELOPING ACROSS THE WATERS. SSW WINDS MAY INCREASE TO 20-25
KT FROM LATE WED INTO THU AHEAD OF APPROACHING COLD FRONT. SHOWERS
AND TSTMS SHOULD BE MOST NUMEROUS THU WITH APPROACHING COLD FRONT.
FRIDAY...COLD FRONT ALONG WITH WIND SHIFT FROM SSW TO WNW SHOULD
COMMENCE. VSBY WILL IMPROVE WITH THE WIND.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 2 AM EDT TUESDAY
FOR ANZ233>235-237.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT TUESDAY
FOR ANZ254>256.
&&
$$
SYNOPSIS...NOCERA/JWD
NEAR TERM...NOCERA/JWD
SHORT TERM...JWD
LONG TERM...NOCERA
AVIATION...NOCERA/JWD
MARINE...NOCERA/JWD
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1114 AM EDT Mon May 20 2013
.DISCUSSION...
The 12 UTC regional surface analysis showed the western periphery
of the West Atlantic ridge across the Southeast. There appeared to
be an outflow boundary, leftover from Sunday`s thunderstorms in
GA, off the FL Panhandle coast. Visible satellite imagery showed a
well-defined MCV, again leftover from yesterday`s convective
complex, centered over Tallahassee. Vapor imagery and upper air
data showed a ridge axis from Mobile to Ohio, with a weak trough
over the Piedmont. Local radars were quiet so far. Assuming a
surface air parcel of about 90 deg with a dewpoint in the lower to
mid 60s, the SBCAPE at Tallahassee this afternoon would be about
1000 J/Kg.
The large scale environment suggests that the best combination of
deep layer moisture and Q-G forcing will be over our eastern
zones, which is where the statistical guidance consensus has our
highest PoP (30-40% PoP). The 00/06 UTC Convection Allowing Model
(CAM) consensus is on board with this scenario as well. However,
the latest HRRR and 11 UTC local WRF runs indicate more
widespread convection than this, mainly late this afternoon. To
account for this possibility we spread out the PoP more broadly
across our forecast area, with the highest PoP (40%) still being
across South Central GA and North FL.
Mid tropospheric lapse rates were rather high, and most of the
CAPE will be in within the hail growth zone. This suggests the
potential for pulse strong to marginally severe storms later
today, with dime to quarter size hail and microburst wind gusts
of 50 to 60 MPH possible. The weak winds throughout the lower to
mid troposphere will tend to inhibit significant storm
organization and/or updraft rotation, so the coverage and impacts
will be low...about a 5% probability of a severe storm within 25
miles of a point.
&&
.AVIATION [through 18 UTC Tuesday]...
Isolated to scattered TSRA will develop this afternoon, mainly
from 19 UTC through 24 UTC, and mainly around KABY and KVLD where
the probability is 40%. A few storms could produce strong to
severe wind gusts and/or marginally severe hail. The probability
of TSRA elsewhere is 30% or less. Outside of TSRA, VFR vis and
cigs are expected. Patchy fog and/or low clouds are possible for a
brief time Tuesday morning, though confidence is not high enough
to explicitly mention in this TAF package.
&&
.HYDROLOGY...
Only scattered showers and thunderstorms are anticipated over the
next couple of afternoons, and will primarily be confined to areas
east of a line from Tallahassee north to Albany. With weak
steering flow, any storms that do form will have the potential to
meander very slowly or propagate along boundaries. For that
reason, there will remain the potential for isolated nuisance
flooding, but this will have little to no impact on area rivers
and streams.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 90 65 90 66 / 30 30 20 20
Panama City 83 68 84 70 / 20 20 20 10
Dothan 91 67 92 68 / 30 30 20 20
Albany 90 67 91 67 / 40 30 20 20
Valdosta 91 65 88 65 / 40 30 30 20
Cross City 88 65 88 65 / 30 30 40 20
Apalachicola 82 66 82 68 / 20 20 20 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
GA...NONE.
FL...NONE.
GM...NONE.
&&
$$
HYDROLOGY...Harrigan
REST OF DISCUSSION...Fournier
AREA FORECAST DISCUSSION
NWS MIAMI FL
912 AM EDT MON MAY 20 2013
.UPDATE...
HAVE UPDATED GRIDS TO REFLECT CURRENT SHOWER ACTIVITY OVER PALM
BEACH COUNTY, AS WELL AS TWEAKS TO OTHER ELEMENTS. THIS MORNINGS
SOUNDING DOES SHOW THE 500MB TEMP UP TO AROUND -8, WITH A WEAK
CAP. THIS SHOULD ERODE EARLY THIS AFTERNOON, ALLOWING BETTER
DEVELOPMENT OF CONVECTIVE CELLS. SO, MAINLY RAIN SHOWERS THIS
MORNING, WITH POSSIBLY A FEW STRIKES OF LIGHTNING, ALTHOUGH HAVE
YET TO PICK UP ANY THIS MORNING. BUT, THEY CAN NOT BE RULED OUT.
COVERAGE WILL INCREASE LATER TODAY AND SPREAD WESTWARD. THE HRRR IS
SHOWING THAT THE ACTIVITY MAY ACTUALLY BE IN THE WESTERN HALF OF
SOUTH FLORIDA, SO ANOTHER UPDATE MAY BE FORTH COMING LATER THIS
MORNING, IF THE MESOSCALE MODELS CONTINUE TO SHOW THIS TREND OF
CONVECTION OCCURRING TO THE WEST, RATHER THAN THE EAST COAST.
&&
.PREV DISCUSSION... /ISSUED 738 AM EDT MON MAY 20 2013/
AVIATION...
A SHORTWAVE TROUGH COMBINED WITH PLENTY OF MOISTURE...DAYTIME
HEATING AND LIGHT AND VARIABLE LOW-LEVEL FLOW WILL KEEP THE RAINFALL
CHANCES UP TODAY ACROSS SOUTH FLORIDA...ESPECIALLY THROUGH THE
AFTERNOON AND EVENING PERIODS. ADDITIONALLY...A FEW SHOWERS THAT ARE
CURRENTLY DEVELOPING OVER THE OFFSHORE ATLANTIC WATERS WILL CONTINUE
TO TRACK WEST AND MAY BEGIN TO SPREAD ASHORE THROUGH THE MORNING
HOURS. INCLUDED VCSH FOR THE EAST COAST TERMINALS THROUGH THE
MORNING PERIOD AND VCTS THROUGH THE AFTERNOON/EVENING PERIODS FOR
ALL SITES. PERIODS WITH SUB-VFR CONDITIONS WILL REMAIN POSSIBLE IN
AND AROUND THIS ACTIVITY TODAY.
PREV DISCUSSION... /ISSUED 357 AM EDT MON MAY 20 2013/
DISCUSSION...
MAIN FOCUS FOR THIS FORECAST PACKAGE IS THE POSSIBILITY FOR STRONG
TO SEVERE THUNDERSTORMS ACROSS THE AREA THIS AFTERNOON.
DEEPER MOISTURE OVER THE ATLANTIC WATERS CONTINUES TO PRODUCE
ISOLATED SHOWERS EARLY THIS MORNING. THESE SHOWERS SHOULD CONTINUE
TO SLOWLY PUSH TOWARD THE EAST COASTAL AREAS UNDER WEAK EASTERLY
FLOW. HEADING INTO THE PEAK HEATING HOURS OF THE DAY THE FOCUS WILL
SHIFT TO POSSIBLE STRONG TO SEVERE THUNDERSTORM DEVELOPMENT ACROSS
MUCH OF THE AREA. DEEP MOISTURE ADVECTION INTO THE SOUTH FLORIDA
PENINSULA WILL CONTINUE THROUGH THE LATE MORNING AND EARLY AFTERNOON
HOURS. AS A RESULT...MODEL SOUNDINGS DEPICT PWAT VALUES AS HIGH AS
1.75 INCHES. THIS COMBINED WITH WEAK OVERALL STEERING FLOW WILL
ALLOW FOR VERY HEAVY RAINFALL AND THE POSSIBILITY OF LOCALIZED
FLOODING ASSOCIATED WITH ANY STORMS THAT DEVELOP.
THERMODYNAMIC PARAMETERS ARE ALSO EXPECTED TO BE FAVORABLE WITH CAPE
VALUES APPROACHING 3000 J/KG AND LIFTED INDICES RANGING FROM -6C TO
-8C WITH LITTLE IF ANY CAPPING. NORMALLY THIS WOULD BE ENOUGH TO
SPARK A FEW STRONG STORMS...BUT A FAIRLY BROAD H5 SHORTWAVE IS ALSO
EXPECTED TO SLIDE ACROSS THE FLORIDA PENINSULA THIS AFTERNOON WHICH
WILL ACT TO ENHANCE THUNDERSTORM DEVELOPMENT. THIS SHORTWAVE WILL
PROVIDE EXTRA COOLING ALOFT NEEDED FOR STRONG TO SEVERE
THUNDERSTORMS. POINT SOUNDINGS ACROSS THE AREA DEPICT 500 MB
TEMPERATURES AROUND -12C WHICH IS SEVERAL DEGREES COLDER THAN THE
AVERAGE 500 MB TEMPERATURE FOR THIS DATE. ALL OF THESE PARAMETERS
COMBINED WILL AIDE IN THE DEVELOPMENT OF ISOLATED SEVERE
THUNDERSTORMS WITH THE MAIN IMPACTS BEING GUSTY WINDS...LARGE
HAIL...AND LOCALIZED FLOODING. CURRENT THINKING IS THAT
THUNDERSTORMS WILL INITIATE ACROSS THE NORTHERN INTERIOR AND WITH
SUCH WEAK STEERING FLOW...SHOULD BE MAINLY OUTFLOW DRIVEN AND DRIFT
SLOWLY TOWARD THE EAST COAST METRO AREAS.
KEPT CHANCES FOR THUNDERSTORMS OVERNIGHT TONIGHT AND INTO TUESDAY
MORNING AS MID LEVEL DYNAMICS SHOULD PERSIST WITH THE LINGERING
SHORTWAVE. ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL BE LIKELY
TUESDAY AFTERNOON BUT 500 MB TEMPERATURES ARE EXPECTED TO BE A BIT
WARMER WITH SLIGHTLY BETTER LOW LEVEL CAPPING. STILL COULD NOT RULE
OUT AN ISOLATED STRONG STORM WITH DIURNAL HEATING AND DEEP MOISTURE
STILL IN PLACE.
AFTERNOON SHOWER AND THUNDERSTORM CHANCES WILL PERSIST THROUGH THE
REMAINDER OF THE WEEK AND INTO THE WEEKEND AS THE H5 SHORTWAVE
LINGERS ACROSS THE FLORIDA PENINSULA. IT IS EXPECTED TO SLOWLY
RETREAT EACH DAY ALLOWING HIGHER H5 HEIGHTS TO SLOWLY BUILD INTO THE
AREA WHILE STILL REMAINING IN A FAIRLY WET PATTERN.
MARINE...
NO MARINE ISSUES ARE EXPECTED OUTSIDE OF ANY THUNDERSTORMS THAT
AFFECT THE LOCAL WATERS. LIGHT TO MODERATE EAST AND SOUTHEAST
WINDS WILL CONTINUE THROUGH AT LEAST THE EARLY HALF OF THE WEEK
ACROSS THE ATLANTIC WATERS WHILE REMAINING MORE LIGHT AND VARIABLE
ACROSS THE GULF WATERS. THROUGH THE LATTER HALF OF THE WEEK WINDS
ARE EXPECTED TO BECOME LIGHT ACROSS ALL LOCAL WATERS.
FIRE WEATHER...
DEEP MOISTURE WILL REMAIN IN PLACE ACROSS THE SOUTH FLORIDA
PENINSULA THROUGH THE PERIOD KEEPING MINIMUM RELATIVE HUMIDITY
LEVELS WELL ABOVE CRITICAL THRESHOLDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 73 86 73 / 60 40 60 40
FORT LAUDERDALE 85 75 86 76 / 60 40 50 40
MIAMI 86 74 87 75 / 50 40 50 30
NAPLES 88 71 88 71 / 30 30 40 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...13/SI
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
745 AM EDT MON MAY 20 2013
.SHORT TERM /TODAY THROUGH TUESDAY NIGHT/...
THE IMMEDIATE SHORT TERM WILL BE SPENT DEALING WITH RESULTS OF A
NEARLY 24 HOUR LONG RAINFALL EVENT WHICH INCLUDES THE DEVELOPMENT
OF LOW CLOUDS AND FOG. GENESIS REGION FOR THIS IS THE CAROLINAS
AND OVER THE LAST SEVERAL HOURS HAS SPREAD WEST INTO THE NORTHEAST
MOUNTAINS AND JUST NOW ENTERING INTO THE REMAINDER OF NORTH
GEORGIA. NAM12 VERY BULLISH ON FOG DEVELOPMENT THROUGH THIS
MORNING WITH WIDESPREAD CONDENSATION PRESSURE DEFICIT VALUES RIGHT
AROUND ZERO. GFS NOT NEARLY THIS AGGRESSIVE BUT BASED ON
OBS...LOOKS LIKE NAM12 IS INITIALIZING BETTER AT THIS POINT AND
WILL FAVOR ITS SOLUTION.
FOG AND LOW CLOUDS TO SLOWLY LIFT DURING THE MORNING HOURS BUT
ENOUGH LOW LEVEL MOISTURE REMAINS TO MAINTAIN A CIG DECK FOR MUCH
OF THE DAY. AS FAR AS POPS AREA CONCERNED...MODELS IN AGREEMENT
THAT UPPER RIDGE AXIS WILL SHIFT EASTWARD...GETTING US OUT OF THE
BELT OF NW FLOW AND LIMITING EFFECTS FROM ANY IMPULSES TO OUR
EXTREME EASTERN SECTIONS. AM A LITTLE CONCERNED THAT WEAK SYNOPTIC
WINS WILL ALLOW SEA BREEZE AND DEVELOPING OUTFLOWS PROPAGATE WEST
AND BRING SHOWERS AND THUNDERSTORMS WITH THEM SO HAVE GONE ABOVE
GUIDANCE FORM MY SOUTHEAST ZONES TODAY. HRRR SHOWS SEPARATE
SECTION DEVELOPING DURING THE AFTERNOON. ALTHOUGH THIS REGION IS
CLOSER TO UPPER RIDGE...STRENGTH OF THIS FEATURE IS LIMITED AND
WILL NEED TO CARRY AT LEAST SLIGHT CHANCE POPS ALL ZONES.
LOW CLODS AND FOG NOT QUITE AS PROMINENT IN THE MODELS TUESDAY
MORNING BUT SATELLITE LOOKS LIKE DECENT DEVELOPMENT OVER THE EASTERN
THIRD OF THE REGION...ESPECIALLY THE NORTHEAST MOUNTAINS. THIS
WILL GIVE WAY ONCE AGAIN TO IMPROVING SKY CONDITIONS BY AFTERNOON
BUT POPS LOOK TO BE ON THE INCREASE AGAIN. UPPER RIDGE AXIS
WEAKENS SLIGHTLY IN RESPONSE TO APPROACHING TROUGH.
MEANWHILE...LOW LEVEL INSTABILITY AND LAPSE RATES WILL BE ON THE
INCREASE WITH CAPE VALUES OF NEAR 3000 J/KG PROJECTED LATE
TUESDAY. GIVEN FLOW PATTERN...WOULD EXPECT DEVELOPMENT OVER THE NE
MOUNTAINS FIRST AND THEN PROPAGATING SW TOWARD THE ATLANTA METRO.
HAVE GONE A CONSIDERABLE AMOUNT ABOVE GUIDANCE FOR THESE AREAS.
DEESE
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
UPPER LEVEL TROUGH APPROACHING ON WEDNESDAY AND COMBINED WITH
ASSOCIATED MOIST AND INSTABILITY WILL GIVE POTENTIAL FOR NUMEROUS
SHOWERS AND SCATTERED THUNDERSTORMS ACROSS MAINLY N GA AND MAINLY
SCATTERED SHOWERS AND STORMS FOR CENTRAL GA. A WEAK COLD FRONT GETS
INTO THE AREA LATE THURSDAY...POSSIBILITY ASSOCIATED WITH SOME UPPER
LEVEL SUPPORT...WILL GIVE THE CHANCE FOR SHOWERS AND STORMS. BEST
MOISTURE AND UPPER SUPPORT DRIFTING EAST ON FRIDAY ALLOWING FOR ONLY
A SLIGHT CHANCE OF SHOWERS AND STORMS. OVERALL MOISTURE AND
INSTABILITY APPEAR LACKING SATURDAY INTO MONDAY AND WHILE PRECIP
POTENTIAL IS NOT ZERO IT LOOKS TO BE LESS THAN 20 PERCENT AT THIS
TIME. TEMPERATURES RUNNING WITHIN 5 DEGREES OF NORMAL THROUGH THE
PERIOD.
BDL
&&
.AVIATION...12Z UPDATE...
IFR/LIFR THIS MORNING SHOULD PREVAIL AT THE TERMINAL SITES UNTIL AT
LEAST 14Z...WITH IMPROVEMENT TO VFR BY 17Z. WINDS ARE TRICKY WITH
LIGHT EASTERLY FLOW EXPECTED TO LAST MUCH OF THE MORNING THEN SWITCH
TO SOUTHWEST 5 TO 8 KT BY AFTERNOON. CONVECTION SHOULD REDEVELOP
THIS AFTERNOON BUT WILL BE WIDELY SCATTERED...SO HAVE NOT PUT IN THE
TAFS AT THIS TIME.
//ATL
CONFIDENCE...12Z UPDATE...
MEDIUM ON CIGS AND WINDS.
HIGH ON REMAINING ELEMENTS.
41
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 65 86 64 / 20 5 40 40
ATLANTA 85 68 86 67 / 20 5 30 30
BLAIRSVILLE 82 58 83 63 / 20 5 30 30
CARTERSVILLE 86 65 87 66 / 20 5 20 20
COLUMBUS 88 67 89 67 / 20 10 20 20
GAINESVILLE 83 65 85 66 / 20 5 40 40
MACON 86 64 88 64 / 30 5 30 30
ROME 87 65 88 66 / 20 5 20 20
PEACHTREE CITY 86 62 87 63 / 20 5 30 30
VIDALIA 85 66 87 69 / 40 20 30 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
746 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE OVER THE AREA WILL DISSIPATE THROUGH
MID WEEK WHILE ATLANTIC HIGH PRESSURE PREVAILS UNTIL LATE WEEK. A
COLD FRONT WILL DROP THROUGH THE AREA LATE FRIDAY INTO SATURDAY...
FOLLOWED BY HIGH PRESSURE THROUGH NEXT WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SHORTWAVE TROUGH ALOFT OVER THE REGION TODAY IS COMPLEX PER
LOOPS OF OVERNIGHT WATER VAPOR SATELLITE IMAGERY. THE MAIN UPPER
WAVE WAS DRIFTING E ALONG THE VA/NC BORDER WHILE A WEAK VORTICITY
AXIS EXTENDED S OVER COASTAL GEORGIA IN NE FLORIDA. AN INTERESTING
FEATURE IS THE IMPULSE OVER THE FLORIDA PANHANDLE...OUR ANALYSIS
DID NOT DETECT THIS FEATURE AT 500 MB...IT MAY BE PART MCV AND IS
FORECAST TO VERTICALLY STRETCH THE MID LEVEL TROUGH TODAY.
THE MAIN FORECAST PROBLEMS OF THE DAY ARE TWOFOLD. THERE APPEARS TO
BE HEAVY RAIN POTENTIAL UNTIL MID AFTERNOON ALONG COASTAL SOUTH
CAROLINA AND THEN AN ISOLATED SEVERE WEATHER RISK W OF I-95 IN SE
GEORGIA AND FAR SOUTHERN SOUTH CAROLINA THIS AFTERNOON.
ADDRESSING THE MORNING POTENTIAL FOR DEVELOPING CONVECTIVE RAINS
ALONG THE SOUTH CAROLINA COAST...VERY DEEP MOISTURE IS IN PLAY.
LATEST ANALYSIS INDICATES MOISTURE TRANSPORT CONVERGENCE AND A
INSTABILITY GRADIENT HAS SETUP ALONG THE COAST. MOST OF THE 00Z
HIGH RESOLUTION MODELS HAVE PERFORMED POORLY THROUGH 12 HOURS BUT
SHORT LINES OF HEAVY SHOWERS WERE DEVELOPING E OF I-95 IN SOUTH
CAROLINA AND IT LOOKS LIKE SOME POTENTIAL FOR TRAINING CELLS. THE
TRENDS ARE WORTH WATCHING GIVEN THE 1.8 INCH PWATS LURKING ON THE
LATEST RUC ANALYSIS. WE CONTINUED LIKELY POPS IN PARTS OF THE
CHARLESTON TRI-COUNTY AREA.
THE SECOND ISSUE OF THE DAY WILL TURN TO DIURNAL CONVECTIVE
DEVELOPMENT DURING THE AFTERNOON ONCE AGAIN. MODELS INDICATE A 35 KT
700 MB WIND MAX DEVELOPING OVER THE INLAND CAROLINAS AROUND MIDDAY
AND PUNCHING DUE S INTO GEORGIA W OF I-95 LATER TODAY. 300 MB FLOW
ACROSS SE GEORGIA RAPIDLY BACKS FROM SW TO SE TODAY AND A POCKET OF
UPPER DIFLUENCE IS PROGGED...EVEN THOUGH THE FLOW IS WEAK AT JET
LEVEL. MORNING LOW CLOUDS ARE LIKELY TO DISSIPATE LEAVING A
POTENTIAL FOR SOME INSOLATION LATE MORNING AND EARLY AFTERNOON.
MODEL INSTABILITY PROGS SHOW PARAMETERS A BIT MORE UNSTABLE THAN
ON SUNDAY BACK OVER OUR INLAND ZONES. MUCH OF THIS SCENARIO WILL
DEPEND ONCE AGAIN ON MESOSCALE BOUNDARIES AND SURFACE HEATING.
CANNOT RULE OUT ISOLATED SEVERE THUNDERSTORMS WITH DAMAGING WIND
MARGINALLY SEVERE HAIL OR SOME VERY SMALL SCALE CONVECTIVE
ORGANIZATION. MANY OF THESE STORMS WILL ALSO PRODUCE VERY HEAVY
DOWNPOURS.
THE CONFIDENCE OF EITHER OF THESE SCENARIOS BECOMING REALITY IN
SPACE AND TIME IS NOT GREAT...THUS WE OPTED TO NOT ADD ANY MENTIONS
IN OUR HAZARDOUS WEATHER OUTLOOK UNTIL RADAR TRENDS BECOME MORE
DEFINITIVE AND A 12Z ANALYSIS IS PERFORMED.
HIGH TEMPS TODAY 80 TO 85 DEGREES MOST AREAS WITH LIGHT SOUTH TO
SOUTHEAST WINDS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
UPPER LEVEL TROUGHING OVER THE AREA IS NOT GOING ANYWHERE TONIGHT
BUT WE DO EXPECT CONVECTION TO DECREASE IN COVERAGE AND INTENSITY
DURING THE EVENING. LOW LEVEL COASTAL MOISTURE CONVERGENCE WILL
INCREASE TOWARD DAYBREAK ON TUE ALONG COASTAL SOUTH CAROLINA AND
CONVECTIVE RAINS MAY BREAK OUT ONCE AGAIN THERE. WILL ALSO NEED TO
WATCH TRENDS FOR FOG DEVELOPMENT TONIGHT IF CLOUDS BREAK. WITH
WIDESPREAD CONVECTIVE RAINS EXPECTED TODAY...THERE SEEMS TO BE
INCREASING CHANCES FOR FOG...ESPECIALLY INLAND.
A MOIST AIRMASS WILL PERSIST DURING THE PERIOD ALTHOUGH WE SHOULD
SEE A SLIGHT DECREASE IN PW VALUES BY THURSDAY. THE UPPER
SHORTWAVE WILL SLOWLY DISSOLVE OVERHEAD ON TUESDAY BUT ANOTHER
WAVE WILL APPROACH LATE WEDNESDAY THROUGH THURSDAY. AT THE SURFACE
ATLANTIC HIGH PRESSURE WILL MAINTAIN ITS CONTROL...KEEPING
SOUTHERLY FLOW IN LOW-LEVELS AND ALLOWING DAILY SEABREEZE
CIRCULATIONS TO DEVELOP. CONVECTIVE COVERAGE WILL VARY SOMEWHAT
BETWEEN THE THREE DAYS WITH WEDNESDAY CURRENTLY LOOKING LIKE THE
LEAST ACTIVE DAY DUE TO A LACK OF APPRECIABLE UPPER ENERGY TO WORK
WITH. HIGH TEMPS WILL CLIMB INTO THE MID TO UPPER 80S WITH LOWS IN
THE MIDDLE 60S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
FAIRLY GOOD MODEL CONSISTENCY REGARDING AN UPPER TROUGH SHIFTING
SOUTHEAST AND A COLD FRONTAL PASSAGE FRIDAY OR FRIDAY NIGHT. DRY AND
SLIGHTLY COOLER CANADIAN HIGH PRESSURE LOOKS TO BUILD IN FOR THE
WEEKEND BEFORE SHIFTING OFFSHORE EARLY NEXT WEEK.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
KCHS...A BAND OF SHOWERS WAS DRIFTING TOWARD THE KCHS TERMINAL
THIS MORNING. MODELS CONTINUE TO INDICATE SHOWERS AND ISOLATED
TSTMS INCREASING IN COVERAGE THROUGH MID AFTERNOON WITH THE
SEA BREEZE BECOMING A FOCUS FOR CONVECTION. WE PREVAILED
CONVECTIVE RAINS DURING THE PRIME SEA BREEZE TIME THIS AFTERNOON
WITH VCSH OR TEMPO SHRA UNTIL THEN. TONIGHT...LIKELY VFR BUT
CANNOT RULE OUT MVFR VSBYS LATE IF GROUNDS BECOME WET TODAY.
KSAV...BRIEF MVFR CIGS THIS MORNING BUT CONDITIONS AT DAYBREAK
WERE VFR. THERE COULD BE ADDITIONAL PERIODS OF MVFR CIGS THIS
MORNING OTHERWISE THE MAIN PROBLEM OF THE DAY IS TIMING ANOTHER
BOUT OF DIURNAL CONVECTIVE RAINS. WE MAINTAINED 17Z TO 21Z FROM
PREVIOUS TAFS AS LATEST MODELS ALSO REMAIN CONSISTENT. THERE
COULD BE SOME LOW CLOUDS AND/OR MVFR VSBYS LATE TONIGHT BUT OUR
CONFIDENCE IS LOW AT THIS TIME.
EITHER TERMINAL COULD REPORT THUNDER TODAY AS THE ATMOSPHERE
REMAINS UNSTABLE. WE OPTED TO LEAVE TSRA OUT OF THE PICTURE UNTIL
RADAR TRENDS BECOME BETTER DEFINED.
EXTENDED AVIATION...THE MAIN CONCERN WILL BE SPORADIC REDUCTIONS
IN CEILINGS AND VISIBILITIES...MAINLY ASSOCIATED WITH SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. THE GREATEST CHANCES
WILL BE IN THE AFTERNOON HOURS TUE THROUGH THU...ALTHOUGH EARLY
MORNING FLIGHT RESTRICTIONS CANNOT BE RULED OUT EACH DAY.
&&
.MARINE...
THROUGH TONIGHT...A STRONG RIDGE OF HIGH PRESSURE CENTERED OVER
THE ATLANTIC WILL EXTEND W ACROSS THE COASTAL WATERS...GENERATING
SE AND S WINDS OF 10-15 KT OR LESS AND SEAS IN THE 2-4 FOOT RANGE.
HIGH PRESSURE WILL REMAIN OVER THE WESTERN ATLANTIC THROUGH THURSDAY
NIGHT WITH SEABREEZE CIRCULATIONS DEVELOPING EACH AFTERNOON. A COLD
FRONT WILL DROP THROUGH FRIDAY EVENING OR SATURDAY MORNING WITH A
NORTHEAST FLOW DEVELOPING AS CANADIAN HIGH PRESSURE BUILDS IN. WINDS
AND SEAS WILL LIKELY INCREASE OVER THE WEEKEND IN RESPONSE.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1041 AM CDT MON MAY 20 2013
.DISCUSSION...
ISSUED 1041 AM CDT MON MAY 20 2013
AIRMASS HAS TEMPORARILY STABILIZED ACROSS CENTRAL ILLINOIS THIS
MORNING...THANKS TO OVERNIGHT CONVECTION THAT HAS PUSHED THE MAIN
OUTFLOW BOUNDARY TO A LAFAYETTE INDIANA TO FLORA ILLINOIS LINE.
15Z/10AM LAPS DATA SHOWS SBCAPE VALUES OF LESS THAN 500J/KG
BEHIND THE BOUNDARY...WITH VALUES IN EXCESS OF 2000J/KG AHEAD OF
THE BOUNDARY ACROSS THE FAR SE KILX CWA. FORECAST SOUNDINGS SHOW
AIRMASS GRADUALLY DESTABILIZING BY THIS AFTERNOON...HOWEVER
HIGHEST DEWPOINTS AND SUBSEQUENT CAPE VALUES WILL BE FOCUSED
FURTHER SOUTHEAST OVER THE OHIO RIVER VALLEY. NEVERTHELESS...CAPES
OF 1500 TO 2500J/KG SHOULD BE REALIZED ACROSS MUCH OF THE AREA
LATER TODAY. IN ADDITION...STRONG LOW-LEVEL SHEAR WILL BE IN
PLACE ACROSS THE WESTERN HALF OF THE CWA...WITH 0-6KM BULK SHEAR
VALUES RANGING FROM 45 TO 55KT. COMBINATION OF MODEST INSTABILITY
AND STRONG SHEAR WILL BE ENOUGH TO SUPPORT THE DEVELOPMENT OF
STRONG TO SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO THE
EVENING. HIGH-RES MODELS SUCH AS THE NAM12 AND 4KM HRRR SUGGEST
CONVECTION WILL FIRE ALONG ANOTHER BOUNDARY STRETCHING FROM
EASTERN KANSAS INTO WEST-CENTRAL ILLINOIS AFTER 19Z/2PM. INITIAL
CONVECTIVE MODE WILL BE SUPPORTIVE OF SUPERCELLS THIS AFTERNOON/EARLY
EVENING...BEFORE STORMS BECOME MORE LINEAR BY MID EVENING AS THEY
TRACK FROM SW TO NE ACROSS THE AREA. HAVE MODIFIED POPS/TEMPS JUST
A BIT FOR THE REMAINDER OF THE DAY...BUT CHANGES DO NOT
SIGNIFICANTLY IMPACT GOING FORECAST. CHANCE SHOWERS/STORMS THIS
MORNING...WITH LIKELY POPS ARRIVING ALONG/WEST OF I-55 BY MID TO
LATE AFTERNOON.
BARNES
&&
.AVIATION...
ISSUED 652 AM CDT MON MAY 20 2013
VFR CONDITIONS WILL CONTINUE AT ALL SITES THIS MORNING AND INTO
THIS EVENING. BASED ON RADAR TRENDS NARROW BAND OF RAIN IS NOT
MOVING EAST AND IS REMAINING JUST WEST OF SPI AND OVER PIA. SO NEW
TAFS FOR DEC/CMI/BMI WILL ALL BE DRY...WHILE PIA WILL HAVE -RA FOR
A FEW HOURS AND SPI WILL JUST BE VCTS TIL 15Z. BEYOND THIS...ALL
SITES WILL BE DRY UNTIL THE NEXT ROUND OF THUNDERSTORMS MOVES INTO
THE AREA. ROUGH GUESS IS STORMS WILL DEVELOP WEST OF THE AREA THIS
AFTERNOON AND THEN MOVE INTO THE STATE EARLY THIS EVENING. WILL
HAVE VCTS TO START AT ALL SITES AND THEN PICKED A 4HR BLOCK FOR A
TEMPO GROUP FOR WHEN THINKING BEST CHANCE OF THUNDERSTORMS
IS...THEN DRY COUPLE HOURS AFTER THAT. WINDS WILL BE SOUTHERLY
TO SOUTHWESTERLY THROUGH THE PERIOD...WITH STRONGEST WIND SPEEDS
BEING DURING THE DAY.
AUTEN
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT MON MAY 20 2013
SHORT TERM...TODAY THROUGH THURSDAY
UNSETTLED WEATHER PATTERN EXPECTED THROUGH MID WEEK AS LARGE UPPER
LEVEL LOW OVER NE/SD GRADUALLY WEAKENS AS IT MOVES EASTWARD INTO
THE GREAT LAKES. SPC CONTINUES A SLIGHT RISK OF SEVERE STORMS
ACROSS MUCH OF IL FROM THIS AFTERNOON INTO TUE NIGHT. MODELS HAVE
TRENDED A BIT FASTER WITH WX SYSTEM AND SPC RISK OF SEVERE STORMS
ON WED IS EAST OF IL.
LEADING EDGE OF SHOWERS AND A FEW THUNDERSTORMS AS FAR EAST AS
PEORIA AND JACKSONVILLE WHILE STRONG TO SEVERE STORMS HEADING
TOWARD ST LOUIS METRO AREA EARLY THIS MORNING. MORE NUMEROUS
THUNDERSTORMS WERE OVER CENTRAL AND SW MO INTO SE KS WITH MCS
COMPLEX. ANOTHER AREA OF CONVECTION WAS OVER NE WI WITH ANOTHER
WEAKENING MCS. SURFACE MAP SHOWS DEEPENING 998 MB LOW PRESSURE
OVER CENTRAL SD WITH ITS WARM FRONT OVER NORTHERN WI WHILE ITS
COLD FRONT WAS OVER EASTERN NEBRASKA INTO CENTRAL KS/OK. IL WAS IN
WARM SECTOR WITH MOIST DEWPOINTS IN THE 60S AND EVEN 70F AT OLNEY
AND FAIRFIELD IN SE IL. TEMPS AT 3 AM WERE IN THE LOWER TO MIDDLE
70S EXCEPT RAIN COOLED MID 60S OVER WEST CENTRAL IL.
559 DM 500 MB LOW TO SLOWLY MOVE EAST INTO EASTERN SD BY SUNSET
WITH 998 MB SURFACE LOW MOVING INTO WEST CENTRAL MN. ANOTHER ROUND
OF SEVERE STORMS EXPECTED TO FIRE UP DURING MID/LATE AFTERNOON AND
CONTINUE INTO TONIGHT OVER THE CENTRAL PLAINS AND BE FURTHER EAST
INTO IL LATE THIS AFTERNOON AND TONIGHT. VERY UNSTABLE AIR MASS
WITH CAPES OF 2500-3500 J/KG AND GOOD WIND SHEAR TO AID IN THE
DEVELOPMENT OF SEVERE STORMS INCLUDING SOME SUPERCELLS. SPC HAS
15% RISK OF LARGE HAIL AND DAMAGING WIND GUSTS OVER IL WITH 30%
RISK OF LARGE HAIL FROM I-55 WEST AND 30% RISK OF DAMAGING WINDS
GUSTS FROM I-57 WEST. ALSO HAVE AT LEAST A 5% RISK OF TORNADOS
OVER MUCH OF IL EXCEPT FAR SE IL. HIGHS THIS AFTERNOON AGAIN IN
THE UPPER 80S TO NEAR 90F WITH DEWPOINTS IN THE UPPER 60S AND
LOWER 70S SO WILL FEEL LIKE A MID SUMMER DAY IN JULY.
UPPER LEVEL LOW STAYS IN PLACE NEAR SE SD TUE AND THEN WEAKENS A
BIT TO 562 DM AS IT TRACKS EASTWARD INTO EASTERN IA BY SUNSET WED
WHILE SURFACE LOW MOVES INTO SOUTHERN LAKE MI. ANOTHER SLIGHT RISK
OF SEVERE STORMS OVER MUCH OF IL TUE AFTERNOON/EVENING THOUGH NOT
QUITE AS UNSTABLE AS THIS AFTERNOON...AND SYSTEM IS STARTING TO
WEAKEN SO COVERAGE OF SEVERE STORMS APPEARS LESS. SPC HAS AT LEAST
15% RISK OF DAMAGING WINDS AND LARGE HAIL WITH THE 30% RISK SW IL SW
OF CLAY COUNTY. HIGHS TUE IN THE LOW TO MID 80S. SHOWERS STILL
LIKELY WED WITH A FEW THUNDERSTORMS ESPECIALLY OVER EASTERN IL.
RAINFALL AMOUNTS OF 1 TO 2 INCHES POSSIBLE TODAY THROUGH WED.
WEAKENING UPPER LEVEL TROF MOVES INTO IL THU KEEPING A CHANCE OF
SHOWERS AND ISOLATED THUNDERSTORMS ALONG WITH COOLER TEMPS WITH
HIGHS AROUND 70F FROM I-74 NORTH AND MID 70S IN SE IL.
LONG TERM...THURSDAY NIGHT THROUGH SUNDAY NIGHT
DRY WEATHER FINALLY RETURNS TO CENTRAL/SE IL THU NIGHT THROUGH FRI
NIGHT AS HIGHS PRESSURE SETTLES INTO THE GREAT LAKES REGIONS.
CARRIED 20-40% CHANCE OF SHOWERS AND THUNDERSTORMS FROM SAT
AFTERNOON THROUGH SUNDAY NIGHT OVER CENTRAL AND SE IL WITH SOME
MODELS SHOWING SHORT WAVE RIDGING OVER TOP OF UPPER LEVEL RIDGE INTO
PARTS OF IL THIS WEEKEND. THOUGH CONFIDENCE OF THIS HAPPENING IS LOW.
TEMPS SHOULD MODIFY EARLY NEXT WEEK WITH SOME UPPER LEVEL RIDGING
INTO IL.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS JACKSON KY
1036 AM EDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1036 AM EDT MON MAY 20 2013
PERSISTENT CONVECTION CONTINUES TO AFFECT FAR EASTERN PIKE COUNTY. IN
FACT CONVECTION CONTINUES TO DEVELOP UPSTREAM ALL THE WAY TO EAST OF
COLUMBUS OH. THE GOOD NEWS IS THAT THE BOUNDARY FOCUSING THIS
CONVECTION IS GRADUALLY SHIFTING EAST...AND WILL BE EAST OF PIKE
COUNTY BY EARLY AFTERNOON. THE RAINFALL RATES HAVE ALSO BEEN LESS THE
PAST COUPLE OF HOURS. FOR EXAMPLE THE PHELPS IFLOWS GAGE IS REPORTING
0.71 SINCE THE EVENT BEGAN...WITH 0.51 OF THIS FALLING BETWEEN 09Z
AND 10Z.
ONCE THE BAND OF CONVECTION IN THE FAR EAST MOVES OUT OF THE
STATE...THE 12Z HRRR AND 12Z NAM SHOW NO RAIN OVER OUR AREA FOR THE
REST OF THE DAY. HOWEVER HAVE ELECTED TO LEAVE THE LOW CHANCE
PROBABILITIES OF RAIN FOR THE EAST AND CENTRAL PART OF THE FORECAST
AREA. MORNING SOUNDINGS ARE QUITE UNSTABLE WITH LI OF -8 AT ILN AND -6
AT OHX. AM CONCERNED THAT BOUNDARIES LEFT FROM THIS MORNINGS
CONVECTION COULD FOCUS SOME ADDITIONAL CONVECTION LATER THIS
AFTERNOON.
HAVE UPDATED NDFD FOR LATEST HOURLY TRENDS BUT ZFP DOES NOT NEED AN
UPDATE AT THIS TIME.
UPDATE ISSUED AT 727 AM EDT MON MAY 20 2013
CONVECTION HAS BEEN PERSISTENT ACROSS FAR SOUTHEASTERN KENTUCKY EARLY
THIS MORNING. THE LATEST NAM AND SREF CONTINUE TO SHOW SOME ACTIVITY
LINGERING INTO THE MID-MORNING HOURS. AS SUCH...WILL ALLOW FOR HIGHER
POPS IN THE FAR EAST. THE FOG HAS ALSO BEEN MORE SPOTTY THIS
MORNING...SO WILL DOWNPLAY THIS INTO THE MID-MORNING HOURS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 351 AM EDT MON MAY 20 2013
A LEFTOVER OUTFLOW BOUNDARY MOVING THROUGH SOUTHEASTERN KENTUCKY HAS
SPARKED A BROKEN LINE OF SHOWERS AND THUNDERSTORMS...WITH EVEN A
STRAY SHOWER CURRENTLY AFFECTING THE JKL OFFICE. WILL INCLUDE SOME
ISOLATED POPS EARLY THIS MORNING GIVEN THESE TRENDS...ALTHOUGH THE
MAIN LINE LOOKS TO EXIT THE SOUTHEAST BETWEEN 4 AND 4:30 AM.
OTHERWISE...UPPER LEVEL RIDGING WILL BE BUILDING IN THROUGH THE DAY
TODAY ACROSS THE COMMONWEALTH IN RESPONSE TO A DEEP TROUGH SLOWLY
NUDGING EAST ACROSS THE PLAINS. THIS WILL RESULT IN MORE ISOLATED
CONVECTIVE COVERAGE. DESPITE A LACK OF DEEPER MOISTURE...THE LATEST
FORECAST SOUNDINGS SHOW QUITE A BIT OF INSTABILITY...SO ANYTHING THAT
DOES INITIATE COULD BE STRONG. WILL HIGHLIGHT THIS IN THE HWO. HIGHS
WILL TOP OUT IN THE MID 80S FOR MOST.
SKIES WILL CLEAR OUT TONIGHT...ALLOWING FOR SOME FOG ONCE AGAIN. LOWS
WILL BOTTOM OUT IN THE LOW TO MID 60S. ON TUESDAY...THE PLAINS TROUGH
WILL BE GETTING A LITTLE CLOSER AND ANY CAPPING WILL BE WEAK. WILL
ALLOW FOR SCATTERED CONVECTION DURING THE AFTERNOON HOURS...WITH SOME
OF THIS POSSIBLY BECOMING STRONG ONCE AGAIN...ESPECIALLY NEAR THE
BLUEGRASS COUNTIES. HIGHS WILL SOAR INTO THE UPPER 80S...THREATENING
RECORD HIGHS FOR THE DATE AT JKL AND LOZ.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 425 AM EDT MON MAY 20 2013
THE PERIOD SHOULD BEGIN RATHER ACTIVE AS AN UPPER LEVEL LOW INITIALLY
OVER THE PLAINS/MO VALLEY REGION AND A SHORTWAVE TROUGH EXTENDING TO
ITS SOUTH APPROACHES THE MS VALLEY AND LOWER OH VALLEY REGION TUE
NIGHT INTO EARLY ON WED. THE ASSOCIATED SFC LOW SHOULD DEEPEN A BIT
AS IT TRACKS TOWARD THE WESTERN GREAT LAKES REGION TUE NIGHT INTO
WED. A LOW LEVEL JET SHOULD TRANSPORT RATHER ABUNDANT MOISTURE INTO
THE REGION WITH PW FORECAST TO INCREASE TO AROUND 1.4 TO 1.5 INCHES.
THE UPPER LEVEL LOW WILL GRADUALLY OPEN UP WITH A SHORTWAVE TROUGH
WORKING ACROSS EASTERN KY LATER ON WED INTO WED NIGHT. MODELS BRING
SOME INCREASING WINDS ALOFT INTO THE AREA AT THAT POINT...THOUGH THE
STRONGER SHEAR SHOULD REMAIN TO OUR NORTH. THE UPPER LEVEL LOW SHOULD
WORK SLOWLY EAST SOUTHEAST REACHING THE UPPER OH VALLEY REGION AND
MID ATLANTIC STATES THU NIGHT INTO FRIDAY. AT THE SFC...THE LOW WILL
TRACK INTO THE EASTERN GREAT LAKES WED NIGHT AND THEN NORTHEAST
ACROSS THE ST LAWRENCE VALLEY WITH THE TRAILING COLD FRONT CROSSING
EASTERN KY ON THU.
THERE WILL PROBABLY BE A LULL IN CONVECTION FOR A TIME ON TUE NIGHT
BETWEEN RATHER DIURNALLY DRIVEN CONFECTION FROM TUE AND RESURGENCE
LIKELY TO OUR WEST AND SOUTHWEST WITH STRENGTHENING LOW LEVEL JET AND
APPROACHING UPPER LEVEL SHORTWAVE LATE TUE NIGHT. MODEL FORECAST
INSTABILITY AND SHEAR ALONG WITH TIMING OF MODELS BRINGING PREFRONTAL
CONVECTION INTO EASTERN KY POINT TOWARD THE POSSIBILITY OF STRONG TO
LOCALLY SEVERE STORMS POSSIBLE ANYWHERE IN THE CWA THOUGH THE NORTH
WILL BE CLOSER TO THE STRONGER LOW LEVEL JET CORE AS HIGHLIGHTED BY
SPC DAY 3 OUTLOOK. THE POTENTIAL FOR LOCALLY HEAVY RAIN AND SOME OF
THE STORMS TO BECOME STRONG WILL BE HIGHLIGHTED FOR WED IN THE HWO.
LIKELY POPS WERE USED FOR WED IN LINE WITH THE MODEL CONSENSUS AND
MOS GUIDANCE. THE MAV NUMBERS CONTINUE TO APPEAR TOO WARM UNLESS
THERE ENDS UP BEING LITTLE CLOUD COVER ON WED AND HIGH TEMPS WERE
TRENDED LOWER TOWARD MODEL CONSENSUS/MET GUIDANCE.
POPS WERE CONTINUED BEHIND THE BOUNDARY INTO FRI AS THE UPPER LEVEL
SYSTEM GRADUALLY WORKS ACROSS THE REGION. THE EXTENDED MODELS
APPEAR TO BE A IN A BIT BETTER AGREEMENT WITH THE UPPER LEVEL
LOW/SHORTWAVE TROUGH TO MOVE ACROSS THE AREA THU INTO FRI.
HOWEVER...LATER IN THE PERIOD THE GFS MAY BE SUFFERING FROM SOME
CONVECTIVE FEEDBACK ISSUES ACROSS THE PLAINS TO WESTERN GREAT LAKES
REGION SAT INTO SUN WHILE THE ECMWF CONTINUES TO DEVELOP CONVECTION
WITH DISTURBANCES IN NW FLOW INTERACTING WITH A WARM FRONT ADVANCING
TOWARD THE LOWER OH VALLEY REGION LATE IN THE PERIOD. THE EXTENDED
GRID LOAD MODEL CONSENSUS HAD SLIGHT CHANCE TO CHANCE POPS FOR SUN
AND THIS WAS GENERALLY FOLLOWED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 727 AM EDT MON MAY 20 2013
PATCHY IFR OR WORSE FOG WILL MIX OUT OF THE DEEPER RIVER VALLEYS
THROUGH THE MID-MORNING HOURS. A FEW SHOWERS OR THUNDERSTORMS WILL
BE POSSIBLE DURING PEAK HEATING...HOWEVER THESE SHOULD BE ISOLATED
ENOUGH TO LEAVE OUT THE MENTION AT THE TAF SITES. MVFR FOG WILL
THREATEN LATE TONIGHT ONCE AGAIN.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...GEOGERIAN
LONG TERM...JP
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1124 AM EDT MON MAY 20 2013
LATEST UPDATE...
UPDATE
.SYNOPSIS...
ISSUED AT 330 AM EDT MON MAY 20 2013
A SLOW MOVING LOW PRESSURE SYSTEM WILL BRING SHOWERS AND
THUNDERSTORMS TO SOUTHERN LOWER MICHIGAN TODAY THROUGH WEDNESDAY. A
FEW STRONG TO SEVERE STORMS ARE POSSIBLE DAILY. COOLER AIR WILL MOVE
IN LATE THIS WEEK.
&&
.UPDATE...
ISSUED AT 1120 AM EDT MON MAY 20 2013
LOW CONFIDENCE SEVERE WEATHER WILL DEVELOP THIS AFTERNOON. SOME
STORMS STILL LOOK LIKE THEY WILL FIRE AT SOME POINT TODAY...THOUGH
EXPECTATIONS ARE THAT A WIDESPREAD SEVERE EVENT WILL NOT OCCUR
THIS AFTERNOON. SOME ADJUSTMENTS TO PRECIPITATION CHANCES THIS
MORNING...OTHERWISE REMAINING FORECAST LEFT ALONE WITH THIS
UPDATE.
SLIGHTLY MORE FAVORABLE SET UP SEEMS TO OCCUR THIS EVENING AND
EARLY TONIGHT AND TUESDAY.
UPDATE ISSUED AT 744 AM EDT MON MAY 20 2013
THAT BAND OF SHOWERS AND ISOLATED THUNDERSTORMS HAS NOW MOVED OUT
OF THE AREA SO I LOWERED POPS THROUGH THE MID MORNING HOURS OVER
THE NORTHERN CWA. THAT WAS ASSOCIATED WITH THE 850 MB WARM FRONT...
WHICH IS NOW NORTH OF THE CWA. IT STILL LOOKS LIKE THE ENERGY FROM
THE CONVECTION SOUTHWEST OF CHICAGO SHOULD REACH OUR CWA EARLY
THIS AFTERNOON TOUCHING OFF A SERIES OF STORMS EARLY TO MID
AFTERNOON.
OVERNIGHT TONIGHT THE LOW LEVEL JET IS AIMED AT SOUTHWEST MICHIGAN
SO I EXPECT ANOTHER PERIOD OF THUNDERSTORMS AFTER MIDNIGHT.
UPDATE ISSUED AT 518 AM EDT MON MAY 20 2013
A FEW SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO DEVELOP ON
THE WARM FRONT FROM BIG SABLE POINT TO NORTHEAST KENT COUNTY AS OF
515 AM THIS MORNING. THE STORMS ARE MOVING NORTHEAST AROUND 40 MPH.
WHILE RAP SOUNDINGS DO SHOW OVER AROUND 100 J/KG OF CIN THERE IS
NEARLY 1000 J/KG OF CAPE ONCE THE CIN IS OVERCOME. I EXPECT THE
STORMS TO CONTINUE TO LIFT NORTH AND EAST OUT OF THE CWA BY 9 AM
THIS MORNING. BASED ON THIS I UPDATED THE GRIDS AND ZONES TO
INDICATE POSSIBLE THUNDERSTORMS FROM I-96 NORTH INTO MID MORNING.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY AFTERNOON)
ISSUED AT 330 AM EDT MON MAY 20 2013
PRIMARY SHORT TERM FCST CONCERNS INVOLVE EVALUATION OF
CONVECTIVE/SVR WX POTENTIAL TODAY THROUGH WEDNESDAY.
A WARM FRONT LIFTING NORTH ACROSS OUR AREA LATER TODAY AND
INCREASING INSTABILITY WILL LEAD TO THE DEVELOPMENT OF SHOWERS AND
STORMS. SOME STRONG TO SEVERE STORMS ARE POSSIBLE PARTICULARLY THIS
AFTERNOON AND EVENING AS SB CAPE VALUES POTENTIALLY REACH AROUND
2000-3000 J/KG NEAR TO SOUTH OF I-96 ALONG WITH STRONGLY NEGATIVE
LI/S AND TOTAL TOTALS INDICES INTO THE MID TO UPPER 50S.
SOME 00Z GUIDANCE FCST SOUNDINGS HAVE AN INVERTED V LOOK BY LATER
THIS AFTN/EVENING SO THERE IS POTENTIAL FOR STRONG TO SEVERE STORMS
TO PRODUCE DAMAGING WIND GUSTS. IN ADDITION LARGE HAIL IS ALSO
POSSIBLE BOTH WITH SFC BASED STORMS AND WITH ELEVATED CONVECTION
NORTH OF THE WARM FRONT. CANNOT RULE OUT AN ISOLATED TORNADO NEAR TO
SOUTH OF THE WARM FRONT THIS AFTERNOON AND EVENING ALTHOUGH THIS
POTENTIAL IS MITIGATED SOMEWHAT BY FAIRLY HIGH LCL HEIGHTS.
SCATTERED STRONG TO POTENTIALLY SVR STORMS ARE POSSIBLE AGAIN
TUESDAY ALTHOUGH WE STILL FEEL THAT POTENTIAL TOMORROW IS NOT AS
GREAT AS LATER TODAY WITH A CONSENSUS OF LATEST 00Z GUIDANCE SHOWING
LESS INSTABILITY/MUCH MORE CLOUD COVER AROUND. THE SVR WX THREAT
TUESDAY WILL BE LARGELY CONTINGENT ON HOW CONVECTIVE EVOLUTION
OCCURS TONIGHT AND ON EXTENT ON CLOUD COVER.
THE SEVERE WX THREAT CONTINUES WEDNESDAY AS THE SFC LOW FINALLY
MOVES EAST INTO MICHIGAN AND AS THE UPPER LEVEL SUPPORT/UPPER TROF
AND ASSOCIATED COLD POOL OF AIR ALOFT MOVE IN. THE 12Z ECMWF/00Z GFS
IN PARTICULAR SUGGEST DECENT SVR WX POTENTIAL WEDNESDAY GIVEN THE
TIMING OF THE SFC LOW AND FRONTAL POSITIONS THROUGH OUR REGION. ALL
THINGS CONSIDERED AT THIS TIME WE BELIEVE THE BEST CHC FOR ORGANIZED
SVR WX WILL BE WEDNESDAY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON MAY 20 2013
THE RAIN SHOWERS SHOULD COME TO AN END BY LATE IN THE DAY THURSDAY.
BY THEN THE THREAT FOR THUNDERSTORMS WILL BE SOUTH OF MICHIGAN. A
CANADIAN HIGH WILL MOVE IN FOR THE FRIDAY INTO SATURDAY TIME FRAME.
THIS BRINGS CANADIAN POLAR AIR SOUTH WITH IT SO THERE IS A THE
THREAT OF FROST OVER THE NORTHERN TWO ROWS OF COUNTIES EARLY
SATURDAY MORNING. ANOTHER PACIFIC STORM WILL LIKELY TO TRACK SOUTH
OF THE AREA BUT WILL BRING THE TREAT OF A LIGHT RAIN SHOWERS SUNDAY.
CONFIDENCE IN THIS FORECAST IS ABOUT AVERAGE. THE MODELS ALL AGREE
ON THE OVERALL PATTERN INTO NEXT WEEK. THERE ARE MINOR ISSUES IN THE
DETAILS BUT LITTLE QUESTION THE SYSTEM OVER US NOW WILL BE SHEARED
OUT TO THE EAST BY FRIDAY MORNING. THE LONGWAVE RIDGE WILL SURELY
BUILD TO OUR WEST BEHIND THE DEPARTING SYSTEM. THAT WILL BRING IN
COOLER AIR FRIDAY INTO SATURDAY. THE UPPER RIDGE TO OUR WEST WILL
THEN SLOWLY BUILD EAST OVER TIME PUSHING THE COLD AIR OUT ONCE AGAIN
(EARLY NEXT WEEK). THERE IS SOME QUESTION AS TO WHAT HAPPENS THE
SOME OF THAT PACIFIC SHORTWAVE ENERGY OVER THE WEEKEND AS THE WARM
AIR PUSHES TOWARD US. THE ECMWF KEEPS THE PRECIPITATION SOUTH OF
MICHIGAN THROUGH THE WEEKEND AND THE GFS BRINGS IT IN SUNDAY. I HAVE
LOW CHANCE POPS FOR THAT BUT I AM CURRENTLY THINKING THIS WILL
ACTUALLY MISS US TO THE SOUTH JUST LIKE THE ECMWF SUGGEST.
THE RAIN ON THURSDAY IS DEFORMATION ZONE RELATED AS THE SYSTEM
SHEARS OUT TO THE EAST BUT THERE IS LITTLE OF ANY INSTABILITY WITH
THIS... JUST SHOWERS. THE CONVECTIVE THREAT IS LARGELY OVER BY MID
EVENING WEDNESDAY.
AS FOR THE FROST THREAT... WITH THE CANADIAN HIGH BUILDING IN FRIDAY
INTO SATURDAY... WINDS WILL BECOME LIGHT AND VARIABLE EARLY SATURDAY
MORNING AND SKIES WILL BE CLEAR. DEW POINTS LIKELY WILL FALL INTO
THE LOWER TO MID 30S SO A GOOD SET UP FOR FROST OVER THE NORTHEAST
COUNTIES. AREAS SOUTH OF ROUTE 10 SHOULD STAY WARM ENOUGH FOR THIS
NOT TO BE AN ISSUE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 744 AM EDT MON MAY 20 2013
MOSTLY VFR TODAY INTO TONIGHT. WHILE THERE IS A THREAT OF SEVERE
STORMS IT IS TO NONE SPECIFIC TO TIME IN THE TAFS. SEEMS THE
CONVECTIVE SYSTEM SOUTHWEST OF CHICAGO WILL BE OUR THREAT FOR
THIS AFTERNOON. THE ISSUE THROUGH IS THE WARM FRONT SEEMS TO BE
OVER NORTH CENTRAL LOWER MICHIGAN SO IT MAY BE THE BEST STORMS
WILL BE NORTH OF ROUTE 10...NORTH OF THE WARM FRONT. THE LOW LEVEL
JET DOES NOT IMPACT THE GRR CWA UNTIL AFTER MIDNIGHT. MOST OF THE
MODEL SOUNDING INTO THIS EVENING NEAR THE TAF SITES ARE VERY DRY
THROUGH 300 MB. THAT IS NOT REAL CONDUCIVE FOR CONVECTION. EVEN
THROUGH SURFACE BASED CAPS ARE NEAR 2000 J/KG.
OVERNIGHT ONCE THE LOW LEVEL JET STARTS BEING AIMED AT LOWER
MICHIGAN AFTER MIDNIGHT... I WOULD EXPECT SHOWERS AND
THUNDERSTORMS TO OVERSPREAD THE TAF SITES SO I DO HAVE SHOWERS IN
THAT TAFS AFTER 09Z.
&&
.MARINE...
ISSUED AT 744 AM EDT MON MAY 20 2013
DUE TO THE WATER TEMPERATURES OFF SHORE OF LAKE MICHIGAN ARE IN
THE MID 40S... AND SURFACE DEW POINTS ARE IN THE 60S TODAY PLUS
WINDS ARE NOT ALL THAT STRONG... I EXPECT EXTENSIVE FOG IN THE
NEAR SHORE TO DEVELOP. SO EXPANDED THE FOG INTO THIS AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 330 AM EDT MON MAY 20 2013
WARM AND FAIRLY HUMID WEATHER IS EXPECTED TODAY THROUGH WEDNESDAY.
THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES TODAY
THROUGH WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT MON MAY 20 2013
SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED TODAY THROUGH
WEDNESDAY BUT SIGNIFICANT FLOODING IS NOT ANTICIPATED SINCE
CUMULATIVE RAINFALL AMOUNTS ON AVERAGE OF ONLY AROUND AN INCH OR TWO
ARE ANTICIPATED THROUGH WEDNESDAY NIGHT. HOWEVER LOCALIZED FLOODING
ISSUES MAY OCCUR WITH HEAVIEST STORMS OR WHERE STORMS TRACK ACROSS
THE SAME LOCATION.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...MACZKO
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...WDM
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...WDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1001 AM EDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1000 AM EDT MON MAY 20 2013
BASED ON DRYNESS ARND H85 AS SHOWN ON THE 12Z GRB RAOB...WHERE THE
H85 DEWPT DEPRESSION WAS 11C...TENDED TO TRIM POPS A BIT FOR TODAY.
LATEST RUC MODEL SHOWS THIS DRY AIR OVERSPREADING THE CWA THRU THE
AFTN. MAINTAINED THE HIER CHC POPS OVER THE E HALF OF THE CWA...
WHERE HIER H85 DEWPTS ARE PROGGED TO LINGER LONGER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 449 AM EDT MON MAY 20 2013
UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER SD WITH A
DEEP TROUGH ACROSS THE PLAINS STATES AND A 500 MB RIDGE IN THE UPPER
GREAT LAKES. THE RIDGE GETS PUSHED FURTHER TO THE EAST OVER THE
LOWER GREAT LAKES THIS FORECAST PERIOD WHILE THE TROUGH HEADS SLOWLY
EAST WITH THE 500 MB LOW NOT MOVING VERY MUCH AT ALL.
850-500 MB Q-VECTOR CONVERGENCE AND DEEP MOISTURE REMAIN FOR THIS
FORECAST PERIOD AND THE NAM...ECMWF AND GFS SHOW THIS. TRICKY
FORECAST COMING UP WITH AMOUNT OF CLOUD COVER DUE TO CONVECTION
BEING HARD TO DETERMINE AND THIS OF COURSE WILL HAVE AN EFFECT ON
TEMPERATURES. THE MORE SUN THAT WE SEE...THE WARMER THE TEMPERATURES
WILL BE AND THE GREATER THE INSTABILITY FOR THE THUNDERSTORMS TO
WORK WITH. TEMPERATURES HAVE A BIG BUST POTENTIAL FOR TODAY WITH
CLOUD COVER BEING THE BIG QUESTION. THOUGHT THERE WOULD BE SOME
LIMITED SUNSHINE AND ENDED UP WARMING HIGH TEMPERATURES A FEW
DEGREES...ESPECIALLY OVER THE EAST WHERE THAT AREA IS FURTHER FROM
THE STRONG FORCING AND HAS SOME DRIER AIR AWAY FROM THE SFC WARM
FRONT. DID GRADUALLY BRING HIGH POPS OVER THE CWA TODAY AS SYSTEM
DRAWS CLOSER AND KEPT LIKELY POPS IN FOR TONIGHT AS THERE WILL
PROBABLY BE AN MCS/MCC IN THE AREA BRINGING WIDESPREAD RAINFALL TO
THE AREA. DID NOT HAVE ANY TIME TO LOOK AT SEVERE WEATHER
POTENTIAL...BUT THINKING IS THERE COULD BE A FEW STORMS WITH STRONG
WINDS AND LARGE HAIL AND THE SLIGHT RISK ACROSS THE SOUTHERN CWA
LOOKED REASONABLE. ALL DEPENDS ON AMOUNT OF SUNSHINE SEEN TO THE
SOUTH OF THE AREA AND THAT IS THE QUESTION THAT CANNOT BE ANSWERED
AT THIS TIME.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 515 AM EDT MON MAY 20 2013
THE NEARLY STEADY STATE 500MB LOW TO OUR WEST WILL CONTINUE TO SPIN
ACROSS THE EASTERN DAKOTAS AND WESTERN MN AT 12Z TUESDAY. EXPECT THE
LOW TO SLIDE EASTWARD ON WEDNESDAY...MERGING WITH THE STRONGER LOW
SPINNING OVER EASTERN HUDSON BAY/NORTHERN QUEBEC. THE BEST CHANCE
FOR CONVECTION WILL LINGER ACROSS THE WI BORDER TUESDAY INTO TUESDAY
EVENING...BEFORE SLOWLY COMING TO AN END. FOG OVER LAKE SUPERIOR
WILL SLOWLY BEGIN TO PUSH TO FAR SOUTHERN PORTIONS OF THE
LAKE...WITH LAKE MICHIGAN FOG LIKELY REMAINING STRONG THROUGH MUCH
OF WEDNESDAY WHEN THE DEEPER MOISTURE EXITS THE REGION.
EXPECT COOL NORTHERLY FLOW TO BE THE RULE FROM THURSDAY ON...AS THE
REINFORCING 500MB TROUGH PUSHES IN FROM THE NW. THE LAST OF THE RAIN
SHOULD BE EXITING EASTERN UPPER MI THURSDAY MORNING. DRY WEATHER
SHOULD BE THE RULE FROM THURSDAY AFTERNOON THROUGH AT LEAST THE END
OF THE FORECAST PERIOD /SUNDAY/...AS HIGH PRESSURE DOMINATES THE
REGION.
850MB TEMPS OFF THE 19/12Z ECMWF FALL TO A RATHER COOL 0 TO -3C
THURSDAY NIGHT INTO EARLY FRIDAY...AS COOL HIGH PRESSURE SINKS IN
FROM THE NNW. THE 20/00Z RUN WARMED UP SLIGHTLY AND LINED UP A BIT
BETTER WITH THE GFS...AROUND 0 TO 2C FRIDAY THROUGH SATURDAY. THE
NORMAL HIGH TEMPS FOR THIS TIME OF YEAR ARE IN THE MID 60S FOR MUCH
OF THE CWA...TO NEAR 70F SOUTH CENTRAL AND NEAR THE WI BORDER. WE
SHOULD BE WELL BELOW NORMAL FOR HIGH TEMPS...IN THE 50S ON THURSDAY.
FRIDAY WILL NOT BE MUCH WARMER...WITH A FEW READINGS IN THE LOW TO
MID 60S NEAR THE WI BORDER.
A HIGH AMPLITUDE RIDGE ACROSS THE CENTRAL U.S. UP THROUGH CENTRAL
CANADA WILL CONTINUE TO BUILD...THANKS THE THE BOOKEND 500MB LOWS
OVER THE PACIFIC NORTHWEST AND ACROSS QUEBEC. LOOK FOR THIS RIDGE TO
SLOWLY EDGE EASTWARD...AND RIGHT ACROSS WI/MN/WESTERN UPPER MI AND
LAKE SUPERIOR BY DAYBREAK MONDAY. WARMER AIR WILL SLOWLY CREEP BACK
IN...BUT WITH NO GREAT SOUTHERLY RETURN FLOW...TEMPERATURES WILL
ONLY MODERATE SLIGHTLY EACH DAY...WITH BELOW NORMAL READINGS AND
RELATIVELY LIGHT WINDS STILL BY SUNDAY AS THE LARGE/STRONG HIGH
PRESSURE SYSTEM CENTERED OVER MUCH OF ONTARIO SINKS CLOSER TO THE
AREA. WHILE BOTH THE GFS AND ECMWF HINT AT A COUPLE OF SHORTWAVES
SINKING IN ON THE NW FLOW ALOFT OVER THE UPCOMING WEEKEND. AT THIS
POINT THERE DOESN/T LOOK TO BE ENOUGH MOISTURE AROUND TO RESULT IN
ANYTHING MORE THAN A FEW CLOUDS. IF ANY SHOWERS OR TS DEVELOP...THEY
WILL LIKELY REMAIN NORTH AND EAST...CLOSER TO THE 500MB AND SFC LOW
ACROSS QUEBEC.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 722 AM EDT MON MAY 20 2013
CHALLENGING FCST WILL CONTINUE OVER THE NEXT DAY OR SO.
REDEVELOPMENT OF PCPN IS LIKELY TODAY...BUT NOT SURE EXACTLY HOW
MUCH OR WHEN IT WILL DEVELOP. WILL HAVE VFR CONDITIONS AT IWD UNTIL
PCPN DEVELOPS BY THIS EVENING AND THEN LOW IFR CIGS WILL MOVE IN
WITH HELP FROM MOISTURE OFF THE LAKE. WHILE THERE MAY BE SHRA/TSRA
AT TIMES...DIFFICULT TO PIN DOWN BEST TIME FRAME. AT KCMX...UPSLOPE
E FLOW THRU THE FCST PERIOD SUGGESTS PREVAILING LIFR CONDITIONS. AT
KSAW...MVFR CONDITIONS WILL LIKELY PREVAIL THRU MUCH OF THE FCST
PERIOD UNTIL THIS EVENING WHEN IFR CONDITIONS MOVE IN.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 449 AM EDT MON MAY 20 2013
THE MAIN THREATS FOR THIS PERIOD WILL BE A FEW HIGHER GUSTS AT THE
HIGHEST OBSERVING PLATFORMS...AND THE POTENTIAL FOR FOG. A FEW GUSTS
OF 30-35KTS POSSIBLE THROUGH MONDAY...WITH MOST SITES ABOUT 10KTS
LOWER THANKS TO THE MARINE LAYER. HAVE ALREADY HAD REPORTS OF AROUND
2-5SM VIS OVER W LAKE SUPERIOR...WHICH WILL LIKELY CONTINUE AND
SLOWLY SPREAD E WITH THE BETTER CHANCE OF SHOWERS TODAY. EXPECT FOG
TO LINGER THROUGH TUESDAY /FOR MAINLY S LAKE SUPERIOR/.
EXPECT A RIDGE OVER N MANITOBA TO SLIDE ACROSS JAMES BAY
TONIGHT...AND EXIT E ACROSS QUEBEC TUESDAY NIGHT. IN THE
MEANTIME...A LOW OVER THE EASTERN DAKOTAS AND WESTERN MINNESOTA
TODAY AND TONIGHT SHOULD FILL SLIGHTLY ACROSS SOUTHERN MINNESOTA AND
CENTRAL WISCONSIN ON TUESDAY...AND SLOWLY OVER STRETCHING FROM
SOUTHERN WISCONSIN TO LOWER MICHIGAN DURING THE DAY WEDNESDAY. THE
LOW WILL FINALLY EXIT E ACROSS THE LOWER GREAT LAKES WEDNESDAY
NIGHT. BEHIND THE LOW...STRONG AND COOL HIGH PRESSURE ACROSS N
CENTRAL CANADA WILL EXTEND A RIDGE ACROSS LAKE SUPERIOR LATE
THURSDAY AFTERNOON THROUGH AT LEAST FRIDAY...AND MOST LIKELY THROUGH
THE WEEKEND.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...07
LONG TERM...KF
AVIATION...07
MARINE...KF
AREA FORECAST DISCUSSION
NWS GLASGOW MT
915 AM MDT MON MAY 20 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH WEDNESDAY...
RAINFALL CONTINUES OVER THE EASTERN HALF OF THE CWA THIS MORNING.
MADE A FEW FURTHER ADJUSTMENTS TO THE WESTERN EDGE OF HIGH POPS
WITH EXPECTATION THAT RAIN WILL STAY TO THE EAST OF GLASGOW AND
JORDAN. SIMILAR ADJUSTMENTS ALSO MADE FOR TONIGHT WITH THE UPPER
LOW BEGINNING TO SHIFT EASTWARD. EBERT
6AM UPDATE...THE WESTERN PUSH OF RAIN LOOKS TO FALL SHORT OF
GLASGOW THEREFORE BACKED DOWN THE 100 POPS. PROTON
PREVIOUS SHORT TERM DISCUSSION...TODAY AND TONIGHT...A VERTICALLY
STACKED LOW PRESSURE SYSTEM SITUATED OVER THE DAKOTAS WILL
CONTINUE TO SIT AND SPIN. AS IT DOES...A SHIELD OF STRATIFORM RAIN
WILL CONTINUE TO RETROGRADE FROM EAST TO WEST THOUGH THE
DAY...BEFORE CRASHING BACK TO THE SOUTHEAST THIS AFTERNOON AND
EVENING AS THE LOW BEGINS TO TRANSLATE EASTWARD. DETERMINING THE
MAXIMUM EXTENT OF THE BACK EDGE OF THE RAINFALL SHIELD WILL
CONTINUE TO BE THE MAIN FORECAST CHALLENGE.
THE LATEST NAM HAD THE PRECIPITATION INITIALIZED A BIT FURTHER TO
THE EAST THAN RADAR OBSERVATIONS SHOWED. THUS...FEEL THE
PRECIPITATION SHIELD SHOULD MAKE IT A BIT FURTHER THAN THIS
SOLUTION IS SUGGESTING. THE 00Z ECMWF AND GFS HAVE A LITTLE BETTER
HANDLE ON IT. WILL ADMIT THAT THE HRRR HAS BEEN AN IMPRESSIVE
INFORMER AS IT CAUGHT ONTO THE IDEA THAT THE SHIELD WOULD STOP
RETROGRADING FOR A FEW HOURS OVERNIGHT BEFORE AGAIN PROCEEDING ITS
MARCH FURTHER WEST TOWARD MORNING AND THIS IS WHAT IS OCCURRING.
LENDING FURTHER SUPPORT TO THE GUIDANCE IS THE OBSERVATION OF
RECENT PRESSURE FALLS ACROSS THE CWA. PRESSURES ARE GENERALLY
FALLING BETWEEN 0.5 AND 1 MB PER HOUR FOR THE LAST FEW HOURS.
THEREFORE...WILL FEEL COMFORTABLE WITH A BLEND OF THE
ECMWF/GFS/HRRR MODEL SOLUTIONS FOR DETERMINING A BEST GUESS AS TO
WHERE THE BACK EDGE WILL REACH BEFORE IT BEGINS TO PUSH BACK TO
THE SOUTHEAST. THIS BRINGS IT TO A LINE FROM ABOUT OPHEIM...EXTENDING
SOUTH THROUGH JUST WEST OF GLASGOW...TO THE JORDAN AREA. TO THE
EAST OF THIS LINE...THERE IS A DECENT CHANCE AT A NICE WETTING
RAIN THROUGH TONIGHT. IN FACT...WOULD NOT BE SURPRISED IF SOME
AREAS SEE ONE TO TWO INCHES OF RAINFALL ACCUMULATION BY THE END OF
TONIGHT AND INCLUDED A MENTION OF HEAVY RAIN IN SOME OF THE
EASTERN ZONES THROUGH THE MORNING. TO THE WEST OF THIS LINE...RAIN
CHANCES WILL ONLY BE SHOWERY IN NATURE WITH A FEW HUNDREDTHS OF AN
INCH OF ACCUMULATION THE ABSOLUTE MOST THAT WOULD OCCUR. PRECISE
RAINFALL AMOUNTS WILL DEPEND UPON THE PRECISE LOCATION OF WHERE
THE BACK EDGE OF THIS RAIN SHIELD WINDS UP...AS WELL AS SOME FINER
MESOSCALE DETAILS THAT ARE DIFFICULT TO DETERMINE WITH MUCH
CONFIDENCE. TEMPERATURES ARE KEPT AROUND OR JUST BELOW SEASONAL
NORMALS DUE TO THE PRESENCE OF THE LINGERING UPPER TROUGH.
THE OTHER CONCERN TODAY WILL BE STRONG GUSTY WINDS DUE TO A SHARP
PRESSURE GRADIENT IN ASSOCIATION WITH THE SURFACE LOW ACROSS THE
DAKOTAS. AM EXPECTING THAT THE TIGHT PACKING OF THE ISOBARS COULD
SUPPORT NORTHERLY WINDS ON THE ORDER OF 20 TO 30 MPH WITH SOME
GUSTS EXCEEDING 40 MPH THIS AFTERNOON AND EVENING. WILL HOIST A
LAKE WIND ADVISORY FROM NOON UNTIL 9PM DUE TO THIS CONCERN. THIS
MAY ALSO LEAD TO WIND DRIVEN RAINS IN SOME LOCATIONS WHICH COULD
POSE AS HAZARDS TO TRAVELERS AND PEDESTRIANS ALIKE.
TONIGHT THROUGH WEDNESDAY...THE LOW PRESSURE SYSTEM OVER THE
DAKOTAS VERY GRADUALLY TRANSLATES EASTWARD...SO CONTINUED TO TREND
POPS DOWN AND HAVE PRECIPITATION SHUTTING OFF FROM WEST TO EAST.
WILL LEAVE ONLY A SLIGHT CHANCE OF RAIN SHOWERS IN THE EXTREME SE
ZONES BY LATE TUESDAY NIGHT. ON WEDNESDAY...ANOTHER UPPER TROUGH
WITH CLOSED LOW MOVES INTO THE PACIFIC NORTHWEST AS IT DOES
SO...DIFFLUENT SOUTHWEST FLOW ALOFT IS EXPECTED TO DEVELOP ACROSS
THE CWA. THIS MAY LEAD TO CONVECTIVE SHOWERS ON WEDNESDAY...MAINLY
ACROSS THE SW ZONES. SOME OF THE SOUNDINGS IN THE NAM BUFKIT JUST
WEST OF THE CWA ARE SHOWING TOTAL TOTALS APPROACHING 50 AND LI
BECOMING NEGATIVE. DID NOT INSERT A MENTION OF THUNDER JUST YET DUE TO THE
FACT THAT THE PRIMARY FOCUS WAS ON THE CURRENT RAINFALL SITUATION
AND LAKE WIND POTENTIAL. HOWEVER...FUTURE SHIFTS MAY WANT TO
EVALUATE THE POTENTIAL FOR ANY CONVECTIVE INITIATION TOWARD THE
MIDDLE OF THE WEEK. MALIAWCO
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
THE EXTENDED FEATURES MORE SOUTHWEST FLOW THROUGH THE PERIOD. MOST
DAYS SLIGHT CHANCES OF THUNDERSTORMS SLIDING OFF THE CENTRAL
MONTANA MOUNTAINS INTO THE PLAINS FOR HIGHER POPS WEST AND LOW
POPS EAST. FOR THE WEEKEND THE UPPER LOW BREAKS A GOOD WAVE OFF
AND DRIVES IT THROUGH NORTHEAST MONTANA FOR A BETTER CHANCE OF
THUNDERSTORMS THEREFORE BUMPED UP POPS A TAD FOR THOSE PERIODS.
TEMPERATURES WILL HOLD IN NEAR NORMAL THROUGH THE PERIOD.
MODEL TRENDS ARE SHOWING LOWERING HEIGHTS ON THE GFS FOR NORTHEAST
MONTANA WHICH LEADS TO THE UPPER LOW MOVING TOWARDS THE EAST. IF
THE TREND CONTINUES THEN LIKELY POPS ARE A GOOD BET FOR THE
WEEKEND WITH ELEVATED CONFIDENCE. RMOP/ENSEMBLES ARE SHOWING THAT
ITS A GOOD BET THAT AT SOME POINT THIS UPCOMING WEEKEND FOR A
STRONG THUNDERSTORM EVENT ACROSS EASTERN MONTANA. PROTON
&&
.AVIATION...
MVFR VISIBILITY FROM RAIN WITH MVFR/IFR CEILINGS FOR THE EASTERN
AREAS INCLUDING KSDY AND KGDV THROUGH THE PERIOD AS THEY ARE
CLOSER TO THE LOW OVER SOUTHEASTERN NORTH DAKOTA WHICH IS WRAPPING
AROUND MOISTURE INTO THE LOWER YELLOWSTONE RIVER VALLEY. THIS
TREND LOOKS TO CONTINUE THROUGH THE PERIOD.
VFR FOR WESTERN AREAS INCLUDING KGGW AND KOLF THROUGH THE PERIOD
THE MVFR/IFR CEILING SHIELD LOOKS TO STAY JUST OFF TO THE EAST.
FOR NOW WILL STAY WITH VFR CEILINGS.
WIND WILL BE MORE OF AN ISSUE FOR THE EASTERN SITES WITH THE WINDS
STAYING UP ABOVE 20 KNOTS THROUGH THE END OF THE TAF PERIOD.
PROTON/SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 9 PM MDT THIS EVENING FOR FORT PECK
LAKE FOR CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN
VALLEY...GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS GLASGOW MT
553 AM MDT MON MAY 20 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH WEDNESDAY...
6AM UPDATE...THE WESTERN PUSH OF RAIN LOOKS TO FALL SHORT OF
GLASGOW THEREFORE BACKED DOWN THE 100 POPS. PROTON
TODAY AND TONIGHT...A VERTICALLY STACKED LOW PRESSURE SYSTEM
SITUATED OVER THE DAKOTAS WILL CONTINUE TO SIT AND SPIN. AS IT
DOES...A SHIELD OF STRATIFORM RAIN WILL CONTINUE TO RETROGRADE
FROM EAST TO WEST THOUGH THE DAY...BEFORE CRASHING BACK TO THE
SOUTHEAST THIS AFTERNOON AND EVENING AS THE LOW BEGINS TO
TRANSLATE EASTWARD. DETERMINING THE MAXIMUM EXTENT OF THE BACK
EDGE OF THE RAINFALL SHIELD WILL CONTINUE TO BE THE MAIN FORECAST
CHALLENGE.
THE LATEST NAM HAD THE PRECIPITATION INITIALIZED A BIT FURTHER TO
THE EAST THAN RADAR OBSERVATIONS SHOWED. THUS...FEEL THE
PRECIPITATION SHIELD SHOULD MAKE IT A BIT FURTHER THAN THIS
SOLUTION IS SUGGESTING. THE 00Z ECMWF AND GFS HAVE A LITTLE BETTER
HANDLE ON IT. WILL ADMIT THAT THE HRRR HAS BEEN AN IMPRESSIVE
INFORMER AS IT CAUGHT ONTO THE IDEA THAT THE SHIELD WOULD STOP
RETROGRADING FOR A FEW HOURS OVERNIGHT BEFORE AGAIN PROCEEDING ITS
MARCH FURTHER WEST TOWARD MORNING AND THIS IS WHAT IS OCCURRING.
LENDING FURTHER SUPPORT TO THE GUIDANCE IS THE OBSERVATION OF
RECENT PRESSURE FALLS ACROSS THE CWA. PRESSURES ARE GENERALLY
FALLING BETWEEN 0.5 AND 1 MB PER HOUR FOR THE LAST FEW HOURS.
THEREFORE...WILL FEEL COMFORTABLE WITH A BLEND OF THE
ECMWF/GFS/HRRR MODEL SOLUTIONS FOR DETERMINING A BEST GUESS AS TO
WHERE THE BACK EDGE WILL REACH BEFORE IT BEGINS TO PUSH BACK TO
THE SOUTHEAST. THIS BRINGS IT TO A LINE FROM ABOUT OPHEIM...EXTENDING
SOUTH THROUGH JUST WEST OF GLASGOW...TO THE JORDAN AREA. TO THE
EAST OF THIS LINE...THERE IS A DECENT CHANCE AT A NICE WETTING
RAIN THROUGH TONIGHT. IN FACT...WOULD NOT BE SURPRISED IF SOME
AREAS SEE ONE TO TWO INCHES OF RAINFALL ACCUMULATION BY THE END OF
TONIGHT AND INCLUDED A MENTION OF HEAVY RAIN IN SOME OF THE
EASTERN ZONES THROUGH THE MORNING. TO THE WEST OF THIS LINE...RAIN
CHANCES WILL ONLY BE SHOWERY IN NATURE WITH A FEW HUNDREDTHS OF AN
INCH OF ACCUMULATION THE ABSOLUTE MOST THAT WOULD OCCUR. PRECISE
RAINFALL AMOUNTS WILL DEPEND UPON THE PRECISE LOCATION OF WHERE
THE BACK EDGE OF THIS RAIN SHIELD WINDS UP...AS WELL AS SOME FINER
MESOSCALE DETAILS THAT ARE DIFFICULT TO DETERMINE WITH MUCH
CONFIDENCE. TEMPERATURES ARE KEPT AROUND OR JUST BELOW SEASONAL
NORMALS DUE TO THE PRESENCE OF THE LINGERING UPPER TROUGH.
THE OTHER CONCERN TODAY WILL BE STRONG GUSTY WINDS DUE TO A SHARP
PRESSURE GRADIENT IN ASSOCIATION WITH THE SURFACE LOW ACROSS THE
DAKOTAS. AM EXPECTING THAT THE TIGHT PACKING OF THE ISOBARS COULD
SUPPORT NORTHERLY WINDS ON THE ORDER OF 20 TO 30 MPH WITH SOME
GUSTS EXCEEDING 40 MPH THIS AFTERNOON AND EVENING. WILL HOIST A
LAKE WIND ADVISORY FROM NOON UNTIL 9PM DUE TO THIS CONCERN. THIS
MAY ALSO LEAD TO WIND DRIVEN RAINS IN SOME LOCATIONS WHICH COULD
POSE AS HAZARDS TO TRAVELERS AND PEDESTRIANS ALIKE.
TONIGHT THROUGH WEDNESDAY...THE LOW PRESSURE SYSTEM OVER THE
DAKOTAS VERY GRADUALLY TRANSLATES EASTWARD...SO CONTINUED TO TREND
POPS DOWN AND HAVE PRECIPITATION SHUTTING OFF FROM WEST TO EAST.
WILL LEAVE ONLY A SLIGHT CHANCE OF RAIN SHOWERS IN THE EXTREME SE
ZONES BY LATE TUESDAY NIGHT. ON WEDNESDAY...ANOTHER UPPER TROUGH
WITH CLOSED LOW MOVES INTO THE PACIFIC NORTHWEST AS IT DOES
SO...DIFFLUENT SOUTHWEST FLOW ALOFT IS EXPECTED TO DEVELOP ACROSS
THE CWA. THIS MAY LEAD TO CONVECTIVE SHOWERS ON WEDNESDAY...MAINLY
ACROSS THE SW ZONES. SOME OF THE SOUNDINGS IN THE NAM BUFKIT JUST
WEST OF THE CWA ARE SHOWING TOTAL TOTALS APPROACHING 50 AND LI
BECOMING NEGATIVE. DID NOT INSERT A MENTION OF THUNDER JUST YET DUE TO THE
FACT THAT THE PRIMARY FOCUS WAS ON THE CURRENT RAINFALL SITUATION
AND LAKE WIND POTENTIAL. HOWEVER...FUTURE SHIFTS MAY WANT TO
EVALUATE THE POTENTIAL FOR ANY CONVECTIVE INITIATION TOWARD THE
MIDDLE OF THE WEEK. MALIAWCO
.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
THE EXTENDED FEATURES MORE SOUTHWEST FLOW THROUGH THE PERIOD. MOST
DAYS SLIGHT CHANCES OF THUNDERSTORMS SLIDING OFF THE CENTRAL
MONTANA MOUNTAINS INTO THE PLAINS FOR HIGHER POPS WEST AND LOW
POPS EAST. FOR THE WEEKEND THE UPPER LOW BREAKS A GOOD WAVE OFF
AND DRIVES IT THROUGH NORTHEAST MONTANA FOR A BETTER CHANCE OF
THUNDERSTORMS THEREFORE BUMPED UP POPS A TAD FOR THOSE PERIODS.
TEMPERATURES WILL HOLD IN NEAR NORMAL THROUGH THE PERIOD.
MODEL TRENDS ARE SHOWING LOWERING HEIGHTS ON THE GFS FOR NORTHEAST
MONTANA WHICH LEADS TO THE UPPER LOW MOVING TOWARDS THE EAST. IF
THE TREND CONTINUES THEN LIKELY POPS ARE A GOOD BET FOR THE
WEEKEND WITH ELEVATED CONFIDENCE. RMOP/ENSEMBLES ARE SHOWING THAT
ITS A GOOD BET THAT AT SOME POINT THIS UPCOMING WEEKEND FOR A
STRONG THUNDERSTORM EVENT ACROSS EASTERN MONTANA. PROTON
&&
.AVIATION...
MVFR FOR THE EASTERN AREAS INCLUDING KSDY AND KGDV THROUGH THE
PERIOD AS THEY ARE CLOSER TO THE LOW OVER SOUTHEASTERN NORTH
DAKOTA WHICH IS WRAPPING AROUND MOISTURE INTO THE LOWER YELLOWSTONE
RIVER VALLEY. THIS TREND LOOKS TO CONTINUE THROUGH THE PERIOD.
VFR FOR WESTERN AREAS INCLUDING KGGW AND KOLF THROUGH THE PERIOD
AS THE MVFR CEILING SHIELD LOOKS TO STAY JUST OFF TO THE EAST. FOR
NOW WILL STAY WITH VFR CEILINGS.
WIND WILL BE MORE OF AN ISSUE FOR THE EASTERN SITES WITH THE WINDS
STAYING UP ABOVE 20 KNOTS THROUGH THE END OF THE TAF PERIOD. PROTON
&&
.HYDROLOGY...
THE NEXT COUPLE OF DAYS WILL CONTINUE TO BE VERY WET AS NORTHEAST
MONTANA REMAINS UNDER THE INFLUENCE OF A LARGE UPPER TROUGH AND
VERTICALLY STACKED LOW PRESSURE SYSTEM SITUATED ACROSS THE
DAKOTAS. A LARGE AREA OF STRATIFORM RAIN WILL AFFECT ESPECIALLY EASTERN
AREAS OF THE FORECAST AREA. SOME LOCATIONS COULD PICK UP BETWEEN
ONE AND TWO INCHES OF RAINFALL BY TUESDAY MORNING...ESPECIALLY IN
EASTERN ROOSEVELT AND RICHLAND COUNTIES WHERE THE STEADIEST RAIN
IS EXPECTED.
MOST OF THE BASINS IN NORTHEAST MONTANA WILL BE ABLE TO
ACCOMMODATE THIS AMOUNT OF MOISTURE. HOWEVER THERE IS SOME
CONCERN FOR RAPIDLY RISING STREAMS...FIELD FLOODING AND LOCALIZED
FLOODING IN TOWNS AS THE EVENT PERSISTS. SOME MINOR FLOODING MAY
BECOME AN ISSUE...ESPECIALLY FOR THE AREAS FROM WOLF POINT TO
CIRCLE AND EASTWARD INTO NORTH DAKOTA WHERE THE POTENTIAL FOR RAIN
IS THE HIGHEST.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM NOON TODAY TO 9 PM MDT THIS EVENING FOR
CENTRAL AND SOUTHEAST PHILLIPS...CENTRAL AND SOUTHERN VALLEY...
GARFIELD...MCCONE...PETROLEUM.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
622 AM CDT MON MAY 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CDT MON MAY 20 2013
TODAY AND TONIGHT...
THE BAND OF SHOWERS AND RAIN ACROSS THE SOUTHWESTERN AND NORTHEAST
PORTIONS OF THE FCST AREA SHOULD EXIT SOUTH AND EAST BY
DAYLIGHT...MID MORNING AT THE LATEST. THE RAP...HRRR AND NAM THEN
DROP A SECOND BATCH OF RAIN AND SHOWERS SOUTH OUT OF WRN SD THIS
MORNING AND THIS AFTN. THIS AREA OF RAIN SHOULD PRESUMABLY CONTINUE
MOVING SOUTH THIS EVENING WITH A WEAKENING TREND.
THUNDERSTORM CHANCES ARE VERY LOW IF THE RAP AND NAM ARE CORRECT.
NEITHER INDICATE ANY ELEVATED INSTABILITY FROM 750 MB ON UP AND THE
SFC BASED NAM THUNDERSTORM PROBABILITY CHART IS 10 PERCENT OR LESS.
WINDS INCREASE TO WIND ADVISORY CRITERIA TODAY ACROSS PARTS OF THE
WEST WITH H850 WINDS INCREASING TO 45 KT. THE MET AND MAV GUIDANCE
WERE THE BASIS FOR THE FORECAST WIND SPEEDS WHICH INCREASE TO AROUND
30 MPH. WINDS SHOULD SLACKEN THIS EVENING AS LOW PRESSURE ACROSS THE
NRN PLAINS BEGINS TO FILL.
TEMPERATURES ARE A BLEND OF NAM...GEMREG AND ECM PLUS BIAS
CORRECTION FOR HIGHS AND THE 50S AND 60S TODAY WITH LOWS IN THE 40S
AND 50S TONIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 326 AM CDT MON MAY 20 2013
ON TUESDAY...
THE UPPER LOW IS FORECAST TO MOVE FROM CENTRAL INTO FAR SOUTHEAST
SOUTH DAKOTA. A LOBE ON THE WESTERN PERIPHERY OF THE LOW WILL
ROTATE THROUGH WESTERN NEBRASKA WITH A CHANCE FOR SHOWERS MAINLY
ACROSS NORTH CENTRAL NEBRASKA. DESPITE A MOIST PROFILE...LIFT WILL
BE VERY WEAK...MAINLY IN THE H850-H7 LAYER. HAVE LOWERED POPS TO
NEAR 50 PERCENT FOR SHERIDAN AND WRN CHERRY AND FROM 30-40 PERCENT
ACROSS THE REMAINDER OF NCTRL WITH SLIGHT CHANCE POPS IN SWRN NEBR
IN THE MORNING. REGARDING WINDS...STRONGEST WINDS FORECAST FROM
THE EASTERN PANHANDLE INTO SOUTHWEST NEBR...WHERE SUSTAINED WIND
WILL REACH NEAR 25KT AND GUST NEAR 35KT THROUGH THE DAY. THIS IS
DUE TO DEEP MIX DOWN POTENTIAL WHERE UNIDIRECTIONAL NORTHWEST
WINDS EXTEND FROM THE SFC TO ABOVE 400 MB. THEREFORE A WIND
ADVISORY MAY BE NEEDED IF FORECAST WINDS CONTINUE TO LOOK SIMILAR.
HIGHS WILL BE AFFECTED MOST BY CLOUD COVER/SHOWERS FROM 55-60
NCTRL TO NEAR 70 FAR SW.
TUESDAY NIGHT AND WEDNESDAY...
AS UPPER LOW MOVES SLOWLY EAST ACROSS NRN IOWA...STILL SUPPORTIVE
OF A FEW SHOWERS TUES NIGHT NORTH CENTRAL AND NORTHEAST WEDNESDAY
AS WRAPAROUND MOISTURE STILL PRESENT. AN UPPER RIDGE WILL ALSO
BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. CLEARING SKIES IN
THE WEST AND WEAK HIGH PRESSURE BUILDING IN TO BRING COOLER LOWS
FROM THE UPPER 30S TO LOWER 40S WEST TO NEAR 45 EAST. ONLY A MINOR
CHANGE TO HIGHS WEDNESDAY FROM 62-66 NCTRL TO 67-73 SOUTH.
THURSDAY THROUGH SUNDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. THE PRESENCE
OF A NOCTURNAL LOW LEVEL JET WILL ALSO ALLOW FOR THUNDERSTORMS TO
POSSIBLY DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS
FROM THE UPPER 60S TO LOWER 70S THU-FRI WILL WARM TO THE UPPER 70S
TO LOWER 80S SAT-SUN.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 616 AM CDT MON MAY 20 2013
MIXED VFR/MVFR FLIGHT CONDITIONS TODAY WITH MVFR IN SCATTERED
SHOWERS AND AREAS OF RAIN...MAINLY ACROSS NORTHWEST NEB. THE NAM
SUGGESTS THE RAIN WILL EXIT THE FORECAST AREA AROUND 03Z THIS
EVENING. THEREAFTER...MVFR CIGS MAY PERSIST ACROSS NRN NEB. BEST
APPROACH WOULD BE TO MONITOR CONDITIONS TO AS CONDITIONS ARE
MOSTLY VFR AND LOOK SIGNS OF DETERIORATION BEFORE ASSIGNING MVFR
TO THE KVTN TAF.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 9 AM THIS MORNING TO 6 PM MDT THIS EVENING
FOR NEZ004-022-023-035-056>058.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1015 AM EDT MON MAY 20 2013
.SYNOPSIS...
A FEW SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE TODAY AS A FRONTAL
BOUNDARY REMAINS NEAR OUR AREA. A BETTER THREAT FOR SHOWERS AND
THUNDERSTORMS WILL COME TUESDAY AND BEYOND AS A MORE SIGNIFICANT
FRONT AND LOW PRESSURE SYSTEM MOVE CLOSE TO OUR AREA. THE BIGGER
STORY WILL BE WARMER WEATHER WITH HIGH TEMPERATURES IN THE 70S TO
NEAR 80 THROUGH THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
1000 AM UPDATE...MADE MINOR CHANGES TO SHOW MORE OF A DRY FORECAST
ACROSS OUR AREA NOW AND FOR THE NEXT FEW HOURS AS THE CLOSEST AREA
OF SHOWERS OVER NNY WILL SAFELY PASS TO OUR NORTHEAST. STILL NOT
SEEING ANY BIG TRIGGERS FOR SHOWERS OR CONVECTION THIS AFTERNOON
SO SLIGHT CHANCE POPS SEEMS GREAT. THE HRRR DOES SHOW SOMETHING
CROSSING LAKE ERIE LATE IN THE DAY AND IT DOES MATCH UP NOW WITH A
DEVELOPING LINE OF CONVECTION OVER LOWER MICHIGAN SO WE WILL WATCH
THIS CLOSELY. IN ADDITION WHILE DRY NOW...VIS SATELLITE DOES SHOW
SOME MORE LUMPY OR CONVECTIVE LOOKING CUMULUS OVER THE FAR
NORTHEAST END OF LAKE ONTARIO SO THIS MAY TURN INTO SOMETHING IN
THE NEXT FEW HOURS. AGAIN NOT MUCH EXPECTED BUT ENOUGH AROUND TO
WARRANT AT LEAST A MENTION THIS PM. UNLIKE YESTERDAY SUNSHINE OVER
IS ALREADY OVER THE NORTHERN PART OF THE CWA AND WILL CONTINUE TO
PUSH SOUTH THROUGH MIDDAY. TEMPS LOOK ON TRACK TO REACH THE 70S.
THE PREVIOUS AFD IS BELOW...
4 AM UPDATE...
WK SFC LOW LOCATED ACRS SRN QUEBEC WL SLIDE OFF TO THE EAST TDA AS
UL WV PULLS EAST. AS IT DOES SO A WK SFC TROF WL APPCH NRN ZONES
THIS AFTN BFR IT WASHES OUT. AT THE SAME TIME A STRONG CLOSED LOW
ALOFT WL PINWHEEL ACRS THE NRN PLAINS FOR THE NEXT DAY OR TWO. THIS
LOW WHICH WAS RESPONSIBLE FOR YDA`S TORNADO OUTBREAK ACRS THE SRN
PLAINS IS ESSENTIALLY BLOCKED IN PLACE BY RIDGING TO THE EAST AND
WEST. LOW PROGGED TO BE STACKED THRU TUESDAY SWINGING A WMFNT THRU
THE AREA ON MON NGT.
FOR TDA, PATCHY FOG AND DRIZZLE CAN BE EXPECTED ACRS SRN ZONES AS
MARINE LYR RMNS THRU AT LEAST 12Z. AFT THIS TIME, WINDS BCM MORE
SWRLY LEADING TO SOME IMPROVEMENT IN LOW CLDS. WHILE LOW-LVL
MOISTURE WL RMN IN PLACE THIS AFTN, VRY LITTLE FRCG WL BE AVAILABLE
FOR ANY NOTICEABLE PCPN TDA AND WITH MODELS CONTG TO INDICATE
WIDESPREAD QPF ACRS THE AREA AND GIVEN THEIR PERFORMANCES THE LAST 2
DAYS, HV LWRD POPS OVR ENTIRE CWA TO ISOLD AT BEST. IS THE POTENTIAL
FOR AN ISOLD RUMBLE OR TWO OF THUNDER AND HV INCLUDED MENTION TWD
NOON UP NR BNDRY SLIPPING THRU AND OVRSPRDNG ENTIRE AREA THRU ABOUT
21Z. OF COURSE, LIMITATIONS EXIST STRICTLY FM EXTENSIVE CLD CVR
ALONG WITH WK FRCG BUT FEEL CHCS ARE NOT COMPLETELY NIL SO HV CONTD
ISOLD SHRA/TSRA CHC FOR THE AFTN.
FOR TONIGHT, WMFNT LIFTS THRU WITH OVRNGT LOWS EXPECTED TO RMN ARND
60F. DWPTS WL ONLY DROP INTO THE U50S. SKIES WL RANGE FM
PRTLY-MOCLDY DRG THE NIGHTTIME HRS WITH BNDRY IN VICINITY. SLGT CHC
POPS THRU MOST OF THE OVRNGT HRS THEN SLOWLY INCRSNG TWD DAWN FM THE
WEST AS ISENTROPIC LIFT INCREASES.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
4 AM UPDATE...
SW FLOW CONTS ON TUESDAY PER 00Z NAM AND ECMWF. MODELS PLACE CWA
SQUARELY IN THE WARM SECTOR DRG THE DAY. H5 RIDGE BEGINS TO WEAKEN
DRG THE AFTN AS PLAINS LOW BEGINS TO EJECT TO THE EAST. THIS WL
ALLOW WK S/WV TO IMPACT AREA DRG THE DAY, LEADING TO LKLY POPS AFT
18Z. AIRMASS WL LKLY DESTABILIZE IN WM SECTOR LEADING TO CAPES ARND
1000 J/KG BASED ON TEMPS IN THE LWR 80S AND DWPTS RISING INTO THE
MID-60S.
CHC FOR SHOWERS AND TSTMS CONTINUES THRU THE DAY ON WED AS WMFNT
RMNS TO OUR NORTH AND INSTABILITY GRADUALLY INCREASES. DUE TO
PROXIMITY OF BNDRY, SHOWERS APPEAR TO BE LKLY AT TIMES DRG THE DAY
ACRS CNTRL NY CNTYS WHILE ONLY SCTD THUNDER CAN BE EXPECTED, THUS HV
WORDED GRIDS AS LKLY SHOWERS AND CHANCE THUNDER.
MAV NUMBERS LOOK WAY TOO WARM FOR HIGHS ON WEDNESDAY DUE TO THE
GFS/S LACK OF CLD CVR. THINKING IS THAT MET NUMBERS WILL BE CLOSER
TO REALITY AND VLY LOCALES MAY HIT 80F BUT HILLTOPS WL RMN IN THE
U70S.
HV CONTD LKLY POPS WED NGT AS CD FNT APPCHS WRN NY AND H5 LOW EJECTS
INTO GREAT LKS, FLINGING WVS AT TIMES THRU THE PD. HV MADE VRY FEW
CHGS TO PRVS GRIDS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
445 AM UPDATE...
VERY LITTLE CHANGE FROM INHERITED FCST WITH STRONG COLD FRONT
STILL EXPECTED TO PASS THROUGH THE REGION ON THURSDAY. MODELS
CONTINUE TO ADVERTISE A FAIRLY DECENT COOL DOWN FOR THE UPCOMING
WEEKEND WITH THE LATEST ARRIVING 00Z ECMWF NOT AS COOL AS PREVIOUS
RUNS...WHICH IS NOW MORE IN LINE WITH THE GFS AND CANADIAN-CMC.
THAT SAID...STILL LOOKING FOR OVERNIGHT LOWS TO DIP DOWN INTO THE
MIDDLE TO UPPER 30S ACROSS FAVORED VALLEY LOCATIONS NEXT WEEKEND
WHICH WILL LIKELY LEAD TO FROST CONCERNS. UPCOMING WEEKEND STILL
LOOKING DRY AS STRONG HIGH PRESSURE NOSES SOUTH FROM SOUTHERN
CANADA.
PREVIOUS LONG TERM DISCUSSION... THE EXTENDED FORECAST WILL
FEATURE A DEEP UPPER LEVEL TROF OVER THE NORTHEAST KEEPING TEMPS
WELL BELOW NORMAL THROUGH THE PERIOD AFTER A COLD FRONTAL PASSAGE
ON THURSDAY.
AT THE SFC, A COLD FRONT WILL APPROACH THE REGION WEDNESDAY NIGHT
WITH FROPA ON THURSDAY. WILL CONTINUE WITH HIGH CHC/LIKELY POPS
THROUGH THIS PERIOD ALONG WITH THE CHC FOR THUNDERSTORMS. BUILDING
UPPER LEVEL TROF AND LINGERING POST FRONTAL MOISTURE WILL KEEP THE
THREAT FOR SHOWERS INTO FRIDAY. THE REMAINDER OF THE PERIOD WILL
BE DRY WITH PARTLY TO MAINLY CLEAR SKIES AS SFC HIGH PRES DROPS
SOUTH OVER THE AREA FROM CENTRAL CANADA. LOWS BOTH FRIDAY AND
SATURDAY NIGHT MAY BE COLD ENOUGH FOR FROST.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
FAINT HINTS THROUGH OVERLYING CIRRUS THAT LINGERING MARINE LAYER
IS BEGINNING TO RETREAT AS WINDS BECOME MORE SOUTHERLY WITH TIME
THIS MORNING. IN FACT...SYR HAS ACTUALLY CLEARED OUT AND IS NOW
REPORTING VFR CONDITIONS. IN ANY EVENT...EXPECT THIS TREND TO
CONTINUE THIS MORNING AS WINDS CONTINUE TO VEER AND DAYTIME
HEATING COMMENCES. FOR NOW WE EXPECT IFR CONDITIONS TO LINGER AT
BGM FOR A FEW MORE HRS THROUGH ROUGHLY 14Z WITH IMPROVEMENTS
ANTICIPATED SHORTLY THEREAFTER. AT ELM AND ITH...IF IFR WERE TO
OCCUR THIS MORNING...IT WILL LIKELY ONLY BE BRIEF BEFORE THINGS
IMPROVE. BY LATE MORNING...ALL SITES SHOULD BE VFR WITH WEAK
SOUTHERLY WINDS OF 4-8 KTS PREVAILING REGION WIDE.
AS FOR SHWRS/STORMS...WEAK FRONTAL BOUNDARY NORTH OF THE FCST AREA
MAY SERVE AS A TRIGGER FOR DEVELOPING ACTIVITY. FOR NOW...BEST
POTENTIAL WILL BE FOR SYR AND RME HOWEVER WEAK WIND FIELD ALOFT
AND NO HINT OF ANY APPROACHING UPPER SUPPORT LEADS TO A FAIR AMOUNT
OF UNCERTAINTY AND THUS NO MENTION IN THE FCST AS OF NOW.
FOR TONIGHT...EXPECT POSSIBLE IFR CONDITIONS AFTER 06Z AT AVP IN
MOIST SOUTHWEST FLOW. FOR NOW...OVERALL CONFIDENCE OF RESTRICTIONS
AT REMAINING SITES REMAINS TOO LOW TO INCLUDE IN THE FCST DUE TO
MODEL/S SUGGESTION OF DRIER AIR OVER CENTRAL NY.
OUTLOOK...
TUESDAY/WEDNESDAY/THURSDAY...MVFR POSSIBLE IN SHOWERS/THUNDERSTORMS.
FRIDAY...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...PVN
NEAR TERM...PVN
SHORT TERM...HEDEN/PVN
LONG TERM...CMG
AVIATION...CMG
AREA FORECAST DISCUSSION
NWS RALEIGH NC
937 AM EDT MON MAY 20 2013
.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON
TUESDAY REDUCING THE THREAT OF LOCALLY HEAVY RAIN.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 930 AM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
AN UPPER LEVEL MESO-LOW AND ASSOCIATED 500 MB TROUGH WILL LINGER
OVER THE SOUTHEASTERN COASTAL STATES TODAY...WHILE AT THE
SURFACE...RETURN FLOW AROUND A HIGH OF THE MID-ATLANTIC COAST WILL
KEEP LIGHT GRADUAL UPSLOPE FLOW OVER CENTRAL NORTH CAROLINA. CURRENT
RUN OF THE NAM SHOWS GOOD MOISTURE TRANSPORT AND CONVERGENCE OVER
THE CENTRAL AND EASTERN PORTIONS OF THE STATE. CURRENT SPC
MESO-ANALYSIS SHOWS PW VALUES BETWEEN 1.6 AND 1.8 INCHES ACROSS THE
CWA. THIS PATTERN SHOULD HOLD FOR MUCH OF THE DAY AS CURRENT AXIS OF
PRECIPITATION OVER THE CENTRAL PORTION OF THE CWA GRADUALLY MOVES
EASTWARD INTO THE I-95 CORRIDOR. FURTHER TO THE WEST A SHORTWAVE
TROUGH IS EXPECTED TO SWING THROUGH THE WESTERN HALF OF THE STATE
PROVIDING A LITTLE MORE FORCING FOR AFTERNOON SHOWERS AND
THUNDERSTORMS. HRRR MODEL INDICATES THAT SOME HEAVIER SHOWERS WILL
DEVELOP AND MOVE INTO SOUTHWESTERN COUNTIES THIS AFTERNOON. MUCH OF
THE CENTRAL PORTION OF THE CWA HAS RECEIVED SIGNIFICANT RAINFALL
OVER THE PAST 24 HOURS BUT RAINFALL RATES HAVE BEEN LOW ENOUGH THAT
ANY FLOODING PROBLEMS HAVE BEEN NON-EXISTENT AT THIS TIME. WE WILL
CONTINUE TO MONITOR URBAN AREAS AND SMALL STREAMS FOR FLOODING
ACTIVITY WITH CONTINUED RAINFALL THIS AFTERNOON.
AT THIS HOUR MUCH OF THE AREA IS OVERCAST...BUT SOME BREAKS IN THE
CLOUDS COULD PROVIDE SOME DIFFERENTIAL HEATING BOUNDARIES THIS
AFTERNOON. WHILE SHOWERS AND THE OCCASIONAL THUNDERSTORM WILL BE
PROBABLE THIS AFTERNOON...THE LIKELIHOOD THAT ANY OF THESE STORMS
BECOMES SEVERE IS RELATIVELY LOW. WHILE THERE IS SOME
INSTABILITY...EFFECTIVE SHEAR IS VIRTUALLY NON-EXISTENT AND LAPSE
RATES ARE MODEST AT BEST. NO DCAPE TO WORK WITH MAKES SEVERE WINDS
VERY UNLIKELY. EXPECT LOWER CEILINGS TO CONTINUE TO PREVAIL THROUGH
THE MORNING AND INTO THE AFTERNOON ALSO HINDERING INSTABILITY.
DESPITE THIS...HIGHS SHOULD STILL REACH NEAR THE 80 DEGREE MARK THIS
AFTERNOON AS SOUTHWESTERLY FLOW AND WARM AIR ADVECTION HELP ELEVATE
HIGHS TODAY. -ELLIS
SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE. -BADGETT
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 250 AM MONDAY...
A CONTINUED WEAKENING TREND WITH THE TROUGH AND A GRADUAL SHIFT
EASTWARD WILL MEAN MORE SCATTERED AND LESS CONCENTRATED CONVECTIVE
RAINFALL ON TUESDAY AFTERNOON AND EVENING. SEVERAL MODEL SOLUTIONS
INDICATE THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM THE WESTERN
ATLANTIC OVER PORTIONS OF NC. AFTER A START TO THE DAY WITH LOW
STRATUS AND AREAS OF FOG... PARTLY SUNNY SKIES ARE EXPECTED. HIGHS
SHOULD REBOUND INTO THE LOWER TO MID 80S. HOWEVER... DEW POINTS WILL
STILL BE IN THE MID TO UPPER 60S. THE COOLER MET/NAM GUIDANCE LOOKS
MORE IN LINE WITH THE CURRENT EXPECTATIONS WITH THE SSW FLOW AND
PLENTY OF LOW LEVEL MOISTURE AND BROKEN AFTERNOON CLOUDINESS. WIDELY
SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED. THIS
ACTIVITY WILL DIMINISH TUESDAY EVENING WITH LOSS OF HEATING. PARTLY
CLOUDY SKIES WITH AREAS OF FOG AGAIN EXPECTED LATE AT NIGHT. LOWS IN
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 AM MONDAY...
UPPER LEVEL RIDGE BUILDS BRIEFLY OVER THE AREA ON WEDNESDAY... WHICH
SHOULD DIMINISH THE COVERAGE OF CONVECTION... ALTHOUGH DIURNALLY
DRIVEN THUNDERSTORMS CONTINUE TO BE POSSIBLE WITH THE MOIST AIRMASS
OVER THE AREA. PWATS WILL REMAIN NEAR 1.5... 2 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR. WITH WEAK SHEAR... EXPECTING
PULSE TYPE STORMS. HIGHS IN THE MID 80S... LOWS MID 60S.
UPPER LEVEL RIDGE SHIFTS OFFSHORE THURSDAY. AFTERNOON THUNDERSTORMS
CONTINUE TO BE POSSIBLE IN THE AFTERNOON THURSDAY AS PWATS REMAIN
ABOVE NORMAL. BULK SHEAR INCREASES TO 25 TO 30 KTS... WHICH MAY
SUPPORT SOME MULTICELL ORGANIZATION. THICKNESSES REMAIN NEAR TO
SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY... FAVORING TEMPERATURES
CONTINUING TO A BE A FEW DEGREES ABOVE NORMAL... WITH HIGHS IN THE
80S AND LOWS IN THE UPPER 60S. THE TROUGH OVER THE MIDWEST MOVES
EASTWARD ON THURSDAY... AND THE ATTENDANT COLD FRONT PUSHES ACROSS
THE REGION FRIDAY. TIMING HAS TRENDED FASTER DURING TODAYS MODEL
RUNS... WITH THE FRONT MAKING IT THROUGH THE AREA EARLY FRIDAY...
AND TO THE CAROLINA COAST FRIDAY MORNING. STRONGEST DYNAMIC FORCING
REMAINS NORTH OVER NEW ENGLAND... AND WITH THE TIMING NOW LOOKING
MORE DIURNALLY UNFAVORABLE... DO NOT EXPECT A THREAT OF SEVERE
WEATHER.
&&
.AVIATION /12Z MONDAY THROUGH THURSDAY/...
AS OF 736 AM MONDAY...
MOSTLY MVFR CEILINGS WILL PREVAIL FOR THE NEXT SEVERAL HOURS WITH
SOME HEAVIER SHOWERS EXPECTED...ESPECIALLY AT CENTRAL AND EASTERN
TERMINALS WITH SOME IFR/LIFR CEILINGS POSSIBLE IN HEAVIER SHOWERS.
HEAVY SHOWERS AND THE OCCASIONAL THUNDERSTORM WILL MOVE THROUGH
KRDU...KFAY AND IN A COUPLE OF HOURS...KRWI. FOR NOW TRIAD SITES
KINT AND KGSO SHOULD REMAIN DRY FOR THE NEXT SEVERAL HOURS ALTHOUGH
SOME SHOWERS AND THUNDERSTORMS ARE POSSIBLE AS THE NEXT SHORTWAVE
PULSE MOVES THROUGH THE WESTERN PART OF THE STATE. AS THE AFTERNOON
PROGRESSES...CONDITIONS SHOULD BEGIN TO IMPROVE AS FAR AS CEILINGS
TO AS LOWER LEVELS OF THE ATMOSPHERE GRADUALLY DRY OUT. STILL PLENTY
OF MOISTURE TO MAINTAIN SHOWERS AND THUNDERSTORMS WELL INTO THE
AFTERNOON AND EVENING HOURS. WINDS TODAY SHOULD REMAIN LIGHT AND
FROM A SOUTHWESTERLY OR SOUTH SOUTHWESTERLY DIRECTION -ELLIS
IFR TO LIFR CIGS AND VSBYS SHOULD DEVELOP TONIGHT AND PERSIST INTO
EARLY TUESDAY (13Z-15Z)... THE SCATTERED OUT TO VFR. A FEW SHOWERS
AND THUNDERSTORMS MAY DEVELOP TUESDAY AFTERNOON.
LOW STRATUS AND FOG WILL AGAIN BE PROBLEMATIC TUESDAY NIGHT INTO
EARLY WED... THEN GENERALLY VFR CONDITIONS WED THROUGH THU.
HOWEVER... SCATTERED SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
AGAIN LATE WED AFTERNOON AND ESPECIALLY THURSDAY AS ANOTHER TROUGH
APPROACHES FROM THE WEST.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...ELLIS/BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...ELLIS/BADGETT
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
740 AM EDT MON MAY 20 2013
.SYNOPSIS...
WESTERN ATLANTIC HIGH PRESSURE WILL RIDGE ACROSS THE FORECAST AREA
FOR THE MAJORITY OF THIS WEEK. A DISTURBANCE ALOFT MOVING ACROSS THE
AREA EARLY IN THE WEEK...WILL MAINTAIN THE THREAT FOR SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER EXPECTED
FOR MID WEEK BEFORE A COLD FRONT PUSHES ACROSS THE AREA
FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...SLOW-MOVING SHOWERS AND T-STORMS WITH HEAVY
RAINFALL MAY HAVE LED TO FLOODING ACROSS PORTIONS OF DARLINGTON AND
MARLBORO COUNTIES WHERE FLOOD ADVISORIES AND WARNINGS HAVE BEEN
ISSUED THIS MORNING. FLASH FLOOD GUIDANCE FROM THE ATLANTA RFC WAS
EXCEEDED BY RADAR-ESTIMATED RAINFALL TOTALS ACROSS SEVERAL DRAINAGE
BASINS NEAR THE PEE DEE RIVER...MAINLY ALONG A LINE FROM MONT CLARE
NORTH-NORTHEAST TOWARD BENNETTSVILLE. NO REPORTS OF FLOODING HAVE
YET BEEN RECEIVED...ALTHOUGH RADAR-ESTIMATED STORM-TOTAL RAINFALL
OVER 5.5 INCHES IS INDICATED NEAR THE PEE DEE RIVER EAST OF
SOCIETY HILL.
THE LATEST SEVERAL HRRR RUNS (06-08Z) FOCUS ADDITIONAL HEAVY
RAINFALL THROUGH THE MORNING HOURS ACROSS LUMBERTON...MARION...
CONWAY...WHITEVILLE AND ELIZABETHTOWN...WHERE UPWARD OF 3 INCHES OF
RAIN IS DEPICTED IN THE MODEL ACROSS A LARGE AREA. FORTUNATELY THESE
LOCATIONS RECEIVED FAIRLY LIGHT RAINFALL AMOUNTS YESTERDAY WHICH
MEANS A GOOD PORTION OF ANY NEW RAINFALL SHOULD BE ABSORBED BY SOIL
RATHER THAN CONVERTING IMMEDIATELY TO RUNOFF. HIGH POPS (60-80
PERCENT) WILL BE MAINTAINED IN THE FORECAST THROUGH AFTERNOON.
AT THE COAST SHOWERS HAVE SO BEEN GENERALLY LIGHTER WITH NO FLOODING
CONCERNS. ALTHOUGH THE LATEST FEW HRRR RUNS SHOW AT LEAST SOME
POTENTIAL FOR HEAVY RAIN DURING THE MORNING HOURS AT THE COAST...
THE DEVELOPMENT OF A SEABREEZE SHOULD HELP CLEAR THE BULK OF THESE
SHOWERS OUT WITHIN 5-10 MILES OF THE BEACHES THIS AFTERNOON.
A WEAK UPPER LEVEL DISTURBANCE WILL ELONGATE NORTH-TO-SOUTH TODAY
ACROSS THE CENTRAL CAROLINAS...EVENTUALLY CLEAVING INTO TWO
INDIVIDUAL PIECES TONIGHT. CYCLONIC FLOW SURROUNDING THIS FEATURE
ALOFT IS VERY WEAK AND STORM CELL MOTION IS ANTICIPATED TO BE SLOW
TODAY. WITH PRECIPITABLE WATER VALUES NOW IN THE SUMMER/TROPICAL
RANGE OF 1.6 TO 1.8 INCHES AND MODEL FORECAST SOUNDINGS SHOWING
ALMOST 10000 FEET OF WARM CONVECTIVE CLOUD DEPTH (LCL AROUND 2500 FT
VERSUS AN ENVIRONMENTAL FREEZING LEVEL OF 12500 FT) THERE IS A
GROWING POTENTIAL FOR HEAVY RAINFALL...PERHAPS EVEN EXCESSIVE
RAINFALL AND FLOODING LATER TODAY. I DO NOT PLAN TO ISSUE A FLOOD
WATCH...BUT WILL INCLUDE HEAVY RAIN MENTION IN THE FORECAST GRIDS
AND HAZARDOUS WX OUTLOOK.
A STABILIZING BOUNDARY LAYER AND A WEAKENING UPPER LEVEL DISTURBANCE
TONIGHT SHOULD PRODUCE A RAPID DECREASE IN COVERAGE OF SHOWERS.
SOUTH WINDS MAY STILL ADVECT NOCTURNAL MARINE CONVECTION ONSHORE SO
THE HIGHEST POPS (30-40 PERCENT) WILL REMAIN OVERNIGHT NEAR THE
BEACHES...WITH LESSER CHANCES INLAND. LOWS SHOULD FALL TO 66-69 FOR
MOST AREAS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...HIGH PRESSURE OFFSHORE WILL CONTINUE ITS
INFLUENCE ACROSS THE CAROLINAS...BUT A DECREASING TREND IN
CONVECTION WITH WARMING TEMPS IS EXPECTED THROUGH THE SHORT TERM.
BUILDING 1000-500MB THICKNESSES AND SOME WEAK NVA BEHIND A DEPARTING
SHORTWAVE WILL CREATE SUBSIDENCE WITH INCREASED DRYING THROUGH THE
COLUMN. FORECAST PROFILES SUGGEST SIGNIFICANT DRY AIR ABOVE
800MB...AND THIS IS ECHOED IN PWATS FALLING TO 1.25 INCHES BY
WEDNESDAY. THIS WILL TEND TO INHIBIT MUCH IN THE WAY OF
CONVECTION...BUT WITH TEMPS RISING WELL INTO THE 80S...ISOLATED
CONVECTION WILL REMAIN POSSIBLE...ESPECIALLY TUESDAY. WILL CONTINUE
LOW-CHC POP TUESDAY AND SCHC WEDNESDAY...BUT WOULD NOT BE SURPRISED
IF WED ENDS UP BEING DRY ACROSS THE CWA.
TEMPS WILL RESPOND TO BULGING HEIGHTS...RISING FROM THE LOW/MID 80S
TUESDAY INTO THE MID/UPR 80S WEDNESDAY. LOWS WILL REMAIN WELL ABOVE
NORMAL FOR MID-MAY THANKS TO CONTINUED SOUTHERLY WINDS...FALLING
ONLY INTO THE UPPER 60S BOTH NIGHTS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...PATTERN CHANGE TO OCCUR DURING THE EXTENDED AS
COLD FRONT CROSSES THE AREA FRIDAY...USHERING IN A MUCH DRIER
AIRMASS TO THE CAROLINAS.
BERMUDA HIGH AND MID LEVEL RIDGING WILL PERSIST AT THE START OF THE
PERIOD...BUT FULL LATITUDE TROUGH WILL BEGIN TO DISPLACE THE RIDGE
CAUSING INCREASED CONVECTIVE CHANCES AND SLIGHTLY COOLER TEMPS. GFS
HAS SPED UP TIMING OF FRONT CONSIDERABLY...WHICH DOESN`T MAKE A LOT
OF SENSE BASED OFF RESTRICTIVE ANTECEDENT FLOW OF THE UPPER
PATTERN...AND FAVOR THE SLOWER CMC/ECMWF WHICH HAS THE FROPA
OCCURRING FRIDAY AFTN. THIS WILL SUPPORT ANOTHER DAY OF CONVECTION
AHEAD OF THE FRONT...BUT DRYING WILL OCCUR RAPIDLY BEHIND IT AS HIGH
PRESSURE BUILDS IN FROM THE NW. WHILE OVERALL TEMPERATURE CHANGE
WILL BE MINIMAL...WITH TEMPS ONLY A FEW DEGREES COOLER DURING THE
WKND...IT WILL BE MUCH DRIER...AND A BEAUTIFUL WKND APPEARS TO BE IN
STORE FOR THE AREA WITH TEMPS SLIGHTLY BELOW CLIMO.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 12Z...CURRENTLY VFR/MVFR ALONG THE COAST AND MVFR/IFR INLAND
WITH SOUTH WINDS 5-10 KTS. RADAR IMAGERY SHOWS A BAND OF SHRA
APPROACHING KLBT...AND HEAVIER PCPN COULD PRODUCE TEMPO IFR HERE
WITHIN THE NEXT HOUR OR TWO. -SHRA IS ONGOING NEAR THE COAST AS
WELL...BUT EXPECT VFR/MVFR TO PREVAIL.
MORE SHOWERS/TSTMS ARE POSSIBLE TODAY WITH PWAT VALUES > 1.5 INCHES
AND AN UPPER DISTURBANCE OVER THE CAROLINAS. WILL CARRY VCSH AT ALL
TERMS THROUGH THE AFTN HOURS...WITH BETTER PCPN CHANCES INLAND LATER
TODAY. EXPECT MAINLY VFR THROUGH THE DAY WITH MVFR/TEMPO IFR IN
HEAVIER SHOWERS. S-SW WINDS AOB 10 KTS THIS MORNING WILL INCREASE
TO 10-15 KTS THIS AFTN. RAIN CHANCES DIMINISH AFTER 00Z TUESDAY.
MODEL SOUNDINGS SUGGEST FOG COULD BE AN ISSUE TONIGHT AT KLBT/KFLO
WHERE PLENTY OF RAIN HAS ALREADY FALLEN.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR/IFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
MARINE FORECAST THIS MORNING. PREVIOUS DISCUSSION FROM 300 AM
FOLLOWS...
THE OVERALL PATTERN WILL BE LITTLE CHANGED FROM YESTERDAY WITH
SURFACE HIGH PRESSURE REMAINING ANCHORED ALMOST 1000 MILES EAST OF
CAPE HATTERAS AND LOW PRESSURE MOVING SLOWLY ACROSS THE NORTHERN
PLAINS STATES. THIS WILL ENSURE A LIGHT TO MODERATE SOUTH WIND
ACROSS THE CAROLINA COASTAL WATERS TODAY AND TONIGHT.
SHOWERS AND EMBEDDED THUNDERSTORMS THIS MORNING SHOULD DECREASE IN
COVERAGE THIS AFTERNOON AS THE SEABREEZE CIRCULATION DEVELOPS...BUT
ANOTHER ROUND OF SCATTERED SHOWER ACTIVITY MAY DEVELOP TONIGHT. HIGH
MOISTURE CONTENT OF THE ATMOSPHERE MEANS HEAVY RAINFALL AND MARINE
VISIBILITY RESTRICTIONS ARE THE LARGEST THREATS.
SEAS CURRENTLY RANGE FROM 3-4 FT AT THE CAPE FEAR AREA BUOYS IN A
COMBINATION OF SOUTHEAST SWELL AND SOUTH WIND WAVES.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...RETURN FLOW AROUND BERMUDA HIGH PRESSURE
OFFSHORE CONTINUES THROUGH THE SHORT TERM...WITH SOUTHERLY WINDS OF
10-15 KTS COMMON EACH DAY. SEAS OF 2-3 FT TUESDAY WILL RISE TO 2-4
FT WEDNESDAY THANKS TO SLIGHTLY HIGHER WINDS. WHILE A DEAMPLIYFING
SE SWELL WILL BE PRESENT WITHIN THE WAVE SPECTRUM...SEAS WILL BE
PRIMARILY DERIVED FROM A SOUTHERLY 5-6 SEC WIND WAVE.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...SOUTHERLY WINDS AROUND 15 KTS TO START THE
PERIOD WILL VEER THROUGH THURSDAY TO THE W/SW AS A COLD FRONT
APPROACHES FROM THE NW. THIS FRONT WILL CROSS THE WATERS DURING
FRIDAY...TURNING WINDS QUICKLY TO THE WEST FRIDAY EVE WITH DECREASED
SPEEDS BEFORE WINDS INCREASE FROM THE NORTH FRIDAY NIGHT. SEAS WILL
RISE TO 3-5 FT THURSDAY NIGHT AHEAD OF THE COLD FRONT BEFORE FALLING
BACK TO 2-4 FT LATE FRIDAY THANKS TO THE OFFSHORE COMPONENT OF THE
WIND.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
641 AM EDT MON MAY 20 2013
.SYNOPSIS...
WESTERN ATLANTIC HIGH PRESSURE WILL RIDGE ACROSS THE FORECAST AREA
FOR THE MAJORITY OF THIS WEEK. A DISTURBANCE ALOFT MOVING ACROSS THE
AREA EARLY IN THE WEEK...WILL MAINTAIN THE THREAT FOR SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER EXPECTED
FOR MID WEEK BEFORE A COLD FRONT PUSHES ACROSS THE AREA
FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER FOR THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...SLOW-MOVING SHOWERS AND T-STORMS WITH HEAVY
RAINFALL MAY HAVE LED TO FLOODING ACROSS PORTIONS OF DARLINGTON AND
MARLBORO COUNTIES WHERE FLOOD ADVISORIES AND WARNINGS HAVE BEEN
ISSUED THIS MORNING. FLASH FLOOD GUIDANCE FROM THE ATLANTA RFC WAS
EXCEEDED BY RADAR-ESTIMATED RAINFALL TOTALS ACROSS SEVERAL DRAINAGE
BASINS NEAR THE PEE DEE RIVER...MAINLY ALONG A LINE FROM MONT CLARE
NORTH-NORTHEAST TOWARD BENNETTSVILLE. NO REPORTS OF FLOODING HAVE
YET BEEN RECEIVED...ALTHOUGH RADAR-ESTIMATED STORM-TOTAL RAINFALL
OVER 5.5 INCHES IS INDICATED NEAR THE PEE DEE RIVER EAST OF
SOCIETY HILL.
THE LATEST SEVERAL HRRR RUNS (06-08Z) FOCUS ADDITIONAL HEAVY
RAINFALL THROUGH THE MORNING HOURS ACROSS LUMBERTON...MARION...
CONWAY...WHITEVILLE AND ELIZABETHTOWN...WHERE UPWARD OF 3 INCHES OF
RAIN IS DEPICTED IN THE MODEL ACROSS A LARGE AREA. FORTUNATELY THESE
LOCATIONS RECEIVED FAIRLY LIGHT RAINFALL AMOUNTS YESTERDAY WHICH
MEANS A GOOD PORTION OF ANY NEW RAINFALL SHOULD BE ABSORBED BY SOIL
RATHER THAN CONVERTING IMMEDIATELY TO RUNOFF. HIGH POPS (60-80
PERCENT) WILL BE MAINTAINED IN THE FORECAST THROUGH AFTERNOON.
AT THE COAST SHOWERS HAVE SO BEEN GENERALLY LIGHTER WITH NO FLOODING
CONCERNS. ALTHOUGH THE LATEST FEW HRRR RUNS SHOW AT LEAST SOME
POTENTIAL FOR HEAVY RAIN DURING THE MORNING HOURS AT THE COAST...
THE DEVELOPMENT OF A SEABREEZE SHOULD HELP CLEAR THE BULK OF THESE
SHOWERS OUT WITHIN 5-10 MILES OF THE BEACHES THIS AFTERNOON.
A WEAK UPPER LEVEL DISTURBANCE WILL ELONGATE NORTH-TO-SOUTH TODAY
ACROSS THE CENTRAL CAROLINAS...EVENTUALLY CLEAVING INTO TWO
INDIVIDUAL PIECES TONIGHT. CYCLONIC FLOW SURROUNDING THIS FEATURE
ALOFT IS VERY WEAK AND STORM CELL MOTION IS ANTICIPATED TO BE SLOW
TODAY. WITH PRECIPITABLE WATER VALUES NOW IN THE SUMMER/TROPICAL
RANGE OF 1.6 TO 1.8 INCHES AND MODEL FORECAST SOUNDINGS SHOWING
ALMOST 10000 FEET OF WARM CONVECTIVE CLOUD DEPTH (LCL AROUND 2500 FT
VERSUS AN ENVIRONMENTAL FREEZING LEVEL OF 12500 FT) THERE IS A
GROWING POTENTIAL FOR HEAVY RAINFALL...PERHAPS EVEN EXCESSIVE
RAINFALL AND FLOODING LATER TODAY. I DO NOT PLAN TO ISSUE A FLOOD
WATCH...BUT WILL INCLUDE HEAVY RAIN MENTION IN THE FORECAST GRIDS
AND HAZARDOUS WX OUTLOOK.
A STABILIZING BOUNDARY LAYER AND A WEAKENING UPPER LEVEL DISTURBANCE
TONIGHT SHOULD PRODUCE A RAPID DECREASE IN COVERAGE OF SHOWERS.
SOUTH WINDS MAY STILL ADVECT NOCTURNAL MARINE CONVECTION ONSHORE SO
THE HIGHEST POPS (30-40 PERCENT) WILL REMAIN OVERNIGHT NEAR THE
BEACHES...WITH LESSER CHANCES INLAND. LOWS SHOULD FALL TO 66-69 FOR
MOST AREAS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...HIGH PRESSURE OFFSHORE WILL CONTINUE ITS
INFLUENCE ACROSS THE CAROLINAS...BUT A DECREASING TREND IN
CONVECTION WITH WARMING TEMPS IS EXPECTED THROUGH THE SHORT TERM.
BUILDING 1000-500MB THICKNESSES AND SOME WEAK NVA BEHIND A DEPARTING
SHORTWAVE WILL CREATE SUBSIDENCE WITH INCREASED DRYING THROUGH THE
COLUMN. FORECAST PROFILES SUGGEST SIGNIFICANT DRY AIR ABOVE
800MB...AND THIS IS ECHOED IN PWATS FALLING TO 1.25 INCHES BY
WEDNESDAY. THIS WILL TEND TO INHIBIT MUCH IN THE WAY OF
CONVECTION...BUT WITH TEMPS RISING WELL INTO THE 80S...ISOLATED
CONVECTION WILL REMAIN POSSIBLE...ESPECIALLY TUESDAY. WILL CONTINUE
LOW-CHC POP TUESDAY AND SCHC WEDNESDAY...BUT WOULD NOT BE SURPRISED
IF WED ENDS UP BEING DRY ACROSS THE CWA.
TEMPS WILL RESPOND TO BULGING HEIGHTS...RISING FROM THE LOW/MID 80S
TUESDAY INTO THE MID/UPR 80S WEDNESDAY. LOWS WILL REMAIN WELL ABOVE
NORMAL FOR MID-MAY THANKS TO CONTINUED SOUTHERLY WINDS...FALLING
ONLY INTO THE UPPER 60S BOTH NIGHTS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...PATTERN CHANGE TO OCCUR DURING THE EXTENDED AS
COLD FRONT CROSSES THE AREA FRIDAY...USHERING IN A MUCH DRIER
AIRMASS TO THE CAROLINAS.
BERMUDA HIGH AND MID LEVEL RIDGING WILL PERSIST AT THE START OF THE
PERIOD...BUT FULL LATITUDE TROUGH WILL BEGIN TO DISPLACE THE RIDGE
CAUSING INCREASED CONVECTIVE CHANCES AND SLIGHTLY COOLER TEMPS. GFS
HAS SPED UP TIMING OF FRONT CONSIDERABLY...WHICH DOESN`T MAKE A LOT
OF SENSE BASED OFF RESTRICTIVE ANTECEDENT FLOW OF THE UPPER
PATTERN...AND FAVOR THE SLOWER CMC/ECMWF WHICH HAS THE FROPA
OCCURRING FRIDAY AFTN. THIS WILL SUPPORT ANOTHER DAY OF CONVECTION
AHEAD OF THE FRONT...BUT DRYING WILL OCCUR RAPIDLY BEHIND IT AS HIGH
PRESSURE BUILDS IN FROM THE NW. WHILE OVERALL TEMPERATURE CHANGE
WILL BE MINIMAL...WITH TEMPS ONLY A FEW DEGREES COOLER DURING THE
WKND...IT WILL BE MUCH DRIER...AND A BEAUTIFUL WKND APPEARS TO BE IN
STORE FOR THE AREA WITH TEMPS SLIGHTLY BELOW CLIMO.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...NIGHTTIME SHOWERS ARE INCREASING IN COVERAGE OVER THE
EASTERN CAROLINAS AHEAD OF A WEAK UPPER LEVEL DISTURBANCE OVER THE
WESTERN CAROLINAS. MOISTURE FROM THESE SHOWERS SHOULD CREATE IFR
STRATUS IN FLO/LBT AFTER 08Z. ALONG THE COAST WARMER TEMPERATURES
DUE TO ONSHORE FLOW OFF THE ATLANTIC SHOULD MAINTAIN MVFR CIGS...
ALTHOUGH IT IS NOT IMPOSSIBLE THAT ISOLATED IFR CONDITIONS COULD
DEVELOP NEAR HEAVIER SHOWER ACTIVITY. AFTER DAYBREAK...CIGS WILL
GRADUALLY LIFT TO MVFR/VFR. SOUTHWEST WINDS WILL PREVAIL AOB 10 KTS
WITH GUSTS UP TO 18 KTS ALONG THE COAST LATER IN THE DAY. INCREASED
CHANCES FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
THROUGHOUT THE DAY...SLOWLY TAPERING OFF INTO THE EVENING HOURS.
FOR CURRENT FCST HAVE KEPT IN VCSH GIVEN UNCERTAINTY OF
TIMING/OCCURRENCE OF ANY CONVECTIVE ACTIVITY.
EXTENDED OUTLOOK...AFTN SHOWERS/TSTMS POSSIBLE MONDAY AND
TUESDAY. OTHERWISE PREVAILING VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM MONDAY...NO SIGNIFICANT CHANGES ARE NEEDED TO THE
MARINE FORECAST THIS MORNING. PREVIOUS DISCUSSION FROM 300 AM
FOLLOWS...
THE OVERALL PATTERN WILL BE LITTLE CHANGED FROM YESTERDAY WITH
SURFACE HIGH PRESSURE REMAINING ANCHORED ALMOST 1000 MILES EAST OF
CAPE HATTERAS AND LOW PRESSURE MOVING SLOWLY ACROSS THE NORTHERN
PLAINS STATES. THIS WILL ENSURE A LIGHT TO MODERATE SOUTH WIND
ACROSS THE CAROLINA COASTAL WATERS TODAY AND TONIGHT.
SHOWERS AND EMBEDDED THUNDERSTORMS THIS MORNING SHOULD DECREASE IN
COVERAGE THIS AFTERNOON AS THE SEABREEZE CIRCULATION DEVELOPS...BUT
ANOTHER ROUND OF SCATTERED SHOWER ACTIVITY MAY DEVELOP TONIGHT. HIGH
MOISTURE CONTENT OF THE ATMOSPHERE MEANS HEAVY RAINFALL AND MARINE
VISIBILITY RESTRICTIONS ARE THE LARGEST THREATS.
SEAS CURRENTLY RANGE FROM 3-4 FT AT THE CAPE FEAR AREA BUOYS IN A
COMBINATION OF SOUTHEAST SWELL AND SOUTH WIND WAVES.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...RETURN FLOW AROUND BERMUDA HIGH PRESSURE
OFFSHORE CONTINUES THROUGH THE SHORT TERM...WITH SOUTHERLY WINDS OF
10-15 KTS COMMON EACH DAY. SEAS OF 2-3 FT TUESDAY WILL RISE TO 2-4
FT WEDNESDAY THANKS TO SLIGHTLY HIGHER WINDS. WHILE A DEAMPLIYFING
SE SWELL WILL BE PRESENT WITHIN THE WAVE SPECTRUM...SEAS WILL BE
PRIMARILY DERIVED FROM A SOUTHERLY 5-6 SEC WIND WAVE.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...SOUTHERLY WINDS AROUND 15 KTS TO START THE
PERIOD WILL VEER THROUGH THURSDAY TO THE W/SW AS A COLD FRONT
APPROACHES FROM THE NW. THIS FRONT WILL CROSS THE WATERS DURING
FRIDAY...TURNING WINDS QUICKLY TO THE WEST FRIDAY EVE WITH DECREASED
SPEEDS BEFORE WINDS INCREASE FROM THE NORTH FRIDAY NIGHT. SEAS WILL
RISE TO 3-5 FT THURSDAY NIGHT AHEAD OF THE COLD FRONT BEFORE FALLING
BACK TO 2-4 FT LATE FRIDAY THANKS TO THE OFFSHORE COMPONENT OF THE
WIND.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
956 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A BROKEN LINE OF SHOWERS IS STARTING TO DEVELOP EXTENDING FROM
NORTH CENTRAL MICHIGAN TO WESTERN VIRGINIA. THE CU FIELD CONTINUES
TO DEVELOP ACROSS OUR WESTERN COUNTIES ALONG A NARROW CORRIDOR OF
THETA-E ADVECTION NEAR 850MB AND EXPECT AT LEAST SCATTERED
SHOWERS TO DEVELOP AND MOVE EAST. MU CAPES ARE NEAR 2000 J/KG WITH
STEEPENING MID-LEVEL LAPSE RATES APPROACHING 7 C/KM SO THUNDER
WILL ALSO BE POSSIBLE. EXPECT THE TREND THROUGH EARLY AFTERNOON TO BE FOR
THIS THETA-E RIDGE TO LIFT NORTH ACROSS LAKE ERIE SO ONLY CARRIED
THE CHANCE OF SHOWERS AND THUNDERSTORMS EAST TO ABOUT
CLEVELAND...WITH DECREASING CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH THE AFTERNOON. LEANING TOWARDS THE GFS SOUNDING WHICH ARE
WARMER ALOFT THOUGH 700MB TODAY AND MORE IN LINE WITH THE 12Z ILN
SOUNDING...SUGGESTING WE WILL BE CAPPED FOR THE AFTERNOON. WE WILL
HAVE TO KEEP AN EYE ON THE RADAR THOUGH AS DEWPOINTS ARE ALREADY
IN THE UPPER 60S IN SOME AREAS.
PREVIOUS DISCUSSION...TODAY IS A TOUGH FORECAST. THE HRRR AND
RUC/RAP MODELS HAVE BEEN FORECASTING A NARROW BAND OF
SHOWERS/THUNDERSTORMS TO DEVELOP OVER EASTERN INDIANA EARLY THIS
MORNING AND THEN MOVE EAST. AT 3 AM EDT THE ILN 88D WAS INDICATING
A FINE LINE OVER SE INDIANA. AS EACH HOUR HAS GONE ON THE MODELS
ARE DELAYING THE DEVELOPMENT AND INTENSITY OF THE PRECIPITATION.
NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING ON THIS LINE
UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH. SOME OF THE RADAR
FORECAST OUTPUT FROM SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY
MODELS ARE ALL OVER THE PLACE FOR TODAY...SOME WITH NO SHOWER OR
THUNDERSTORM DEVELOPMENT IN THE FORECAST AREA AND SOME WITH A
LITTLE DEVELOPMENT. THE 4KM WRF NMM MODEL HAS SOME ISOLATED
SHOWERS DEVELOPING. CONFIDENCE IS LOW IN THIS BECAUSE OF SO MUCH
RIDGING ALOFT...BUT WILL FORECAST A CHANCE OF SPRINKLES MAINLY
THIS AM AS THIS LINE MOVES THROUGH. WILL MONITOR THIS AND UPDATE
AS NEEDED.
ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.
NOT MUCH IN THE WAY OF CLOUDS ACROSS THE FORECAST AREA AT 4
AM...HOWEVER...THEY ARE EXPECTED TO DEVELOP THROUGH DAYBREAK.
PARTLY CLOUDY SHOULD HANDLE MOST OF TODAY.
OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT
EXPECTING MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO
STRONG. ERIE MAY GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT
ON THE WARMER SIDE OF GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING
SOUTHWEST FLOW AND WARMER AIR ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.
FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.
FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.
USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.
RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.
THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED. BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
PATCHY MVFR BR WILL BURNOFF QUICKLY THIS MORNING. POTENTIAL EXISTS
FOR SCATTERED TSRA NW OH LATE THIS AFTERNOON AS CAPES APPROACH
3000 J/KG. CONFIDENCE IS STILL LOW AS TO EXACTLY WHERE AND WHEN
SCATTERED TSRA WILL DEVELOP AS STRONG RIDGE REMAINS OVERHEAD AND
SEE NO TRIGGER. MUCH BETTER CHANCE OF TSRA OVERNIGHT TONIGHT.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS OVERNIGHT THROUGH
THURSDAY.
&&
.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS. EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM. MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY. WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KEC/KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
716 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS ARE ON THE INCREASE AS PER THE MODELS. THE THREAT FOR
SPRINKLES STILL SEEMS OK WITH LOW CLOUDS DEVELOPING...SO CONTINUED IT.
THE THREAT FOR SHOWERS AND THUNDERSTORMS THIS AM SEEMED TO HAVE
ENDED ACCORDING TO THE MODELS AND LOOKING AT SATELLITE PICTURES...RADAR
ETC. ADDED PATCHY DENSE FOG TO A FEW AREAS SOUTH OF CLEVELAND.
PREVIOUS DISCUSSION...TODAY IS A TOUGH FORECAST. THE HRRR AND
RUC/RAP MODELS HAVE BEEN FORECASTING A NARROW BAND OF
SHOWERS/THUNDERSTORMS TO DEVELOP OVER EASTERN INDIANA EARLY THIS
MORNING AND THEN MOVE EAST. AT 3 AM EDT THE ILN 88D WAS INDICATING
A FINE LINE OVER SE INDIANA. AS EACH HOUR HAS GONE ON THE MODELS
ARE DELAYING THE DEVELOPMENT AND INTENSITY OF THE PRECIPITATION.
NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING ON THIS LINE
UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH. SOME OF THE RADAR
FORECAST OUTPUT FROM SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY
MODELS ARE ALL OVER THE PLACE FOR TODAY...SOME WITH NO SHOWER OR
THUNDERSTORM DEVELOPMENT IN THE FORECAST AREA AND SOME WITH A
LITTLE DEVELOPMENT. THE 4KM WRF NMM MODEL HAS SOME ISOLATED
SHOWERS DEVELOPING. CONFIDENCE IS LOW IN THIS BECAUSE OF SO MUCH
RIDGING ALOFT...BUT WILL FORECAST A CHANCE OF SPRINKLES MAINLY
THIS AM AS THIS LINE MOVES THROUGH. WILL MONITOR THIS AND UPDATE
AS NEEDED.
ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.
NOT MUCH IN THE WAY OF CLOUDS ACROSS THE FORECAST AREA AT 4
AM...HOWEVER...THEY ARE EXPECTED TO DEVELOP THROUGH DAYBREAK.
PARTLY CLOUDY SHOULD HANDLE MOST OF TODAY.
OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT
EXPECTING MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO
STRONG. ERIE MAY GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT
ON THE WARMER SIDE OF GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING
SOUTHWEST FLOW AND WARMER AIR ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.
FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.
FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.
USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.
RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.
THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED. BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.
&&
.AVIATION /11Z MONDAY THROUGH FRIDAY/...
PATCHY MVFR BR WILL BURNOFF QUICKLY THIS MORNING. POTENTIAL EXISTS
FOR SCATTERED TSRA NW OH LATE THIS AFTERNOON AS CAPES APPROACH
3000 J/KG. CONFIDENCE IS STILL LOW AS TO EXACTLY WHERE AND WHEN
SCATTERED TSRA WILL DEVELOP AS STRONG RIDGE REMAINS OVERHEAD AND
SEE NO TRIGGER. MUCH BETTER CHANCE OF TSRA OVERNIGHT TONIGHT.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS OVERNIGHT THROUGH
THURSDAY.
&&
.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS. EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM. MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY. WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
624 AM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS ARE ON THE INCREASE AS PER THE MODELS. THE THREAT FOR
SPRINKLES STILL SEEMS OK WITH LOW CLOUDS DEVELOPING...SO CONTINUED IT.
THE THREAT FOR SHOWERS AND THUNDERSTORMS THIS AM SEEMED TO HAVE
ENDED ACCORDING TO THE MODELS AND LOOKING AT SATELLITE PICTURES...RADAR
ETC. ADDED PATCHY DENSE FOG TO A FEW AREAS SOUTH OF CLEVELAND.
PREVIOUS DISCUSSION...TODAY IS A TOUGH FORECAST. THE HRRR AND
RUC/RAP MODELS HAVE BEEN FORECASTING A NARROW BAND OF
SHOWERS/THUNDERSTORMS TO DEVELOP OVER EASTERN INDIANA EARLY THIS
MORNING AND THEN MOVE EAST. AT 3 AM EDT THE ILN 88D WAS INDICATING
A FINE LINE OVER SE INDIANA. AS EACH HOUR HAS GONE ON THE MODELS
ARE DELAYING THE DEVELOPMENT AND INTENSITY OF THE PRECIPITATION.
NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING ON THIS LINE
UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH. SOME OF THE RADAR
FORECAST OUTPUT FROM SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY
MODELS ARE ALL OVER THE PLACE FOR TODAY...SOME WITH NO SHOWER OR
THUNDERSTORM DEVELOPMENT IN THE FORECAST AREA AND SOME WITH A
LITTLE DEVELOPMENT. THE 4KM WRF NMM MODEL HAS SOME ISOLATED
SHOWERS DEVELOPING. CONFIDENCE IS LOW IN THIS BECAUSE OF SO MUCH
RIDGING ALOFT...BUT WILL FORECAST A CHANCE OF SPRINKLES MAINLY
THIS AM AS THIS LINE MOVES THROUGH. WILL MONITOR THIS AND UPDATE
AS NEEDED.
ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.
NOT MUCH IN THE WAY OF CLOUDS ACROSS THE FORECAST AREA AT 4
AM...HOWEVER...THEY ARE EXPECTED TO DEVELOP THROUGH DAYBREAK.
PARTLY CLOUDY SHOULD HANDLE MOST OF TODAY.
OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT
EXPECTING MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO
STRONG. ERIE MAY GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT
ON THE WARMER SIDE OF GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING
SOUTHWEST FLOW AND WARMER AIR ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.
FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.
FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.
USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.
RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.
THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED. BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.
&&
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
WITH DEW POINTS CREEPING INTO THE 60S DO EXPECT MORE MVFR BR THIS
MORNING...BUT WIND SHOULD HELP IT FROM BEING TOO WIDESPREAD. SHORT
TERM MODELS NOT IN AGREEMENT ON THE TSRA IN ILLINOIS...LATEST HRRR
MOVE TSRA INTO NW OH BY 12Z. FOR NOW WILL ONLY ADD VCTS TO TOL AND
FDY SINCE CONFIDENCE IS LOW AT THIS TIME.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS MONDAY
EVENING THROUGH THURSDAY.
&&
.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS. EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM. MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY. WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...DJB
MARINE...DJB
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1019 AM CDT MON MAY 20 2013
.UPDATE...MAIN BAND OF CLOUDINESS IS SHIFTING EASTWARD THIS
MORNING...WHICH SHOULD ALLOW FOR A GOOD AMOUNT OF SUNSHINE INTO
THIS AFTERNOON. HIGH TEMPS WERE BUMPED UP A BIT OVERNIGHT AND
STILL SEEM REASONABLE.
BIGGEST CONCERN TODAY INTO TONIGHT IS TIMING AND STRENGTH OF
EXPECTED THUNDERSTORMS. SPC IS MAINTAINING A SLIGHT RISK FOR
SEVERE STORMS ACROSS THE FORECAST AREA FOR TODAY. LATEST NAM AND
RAP SOUNDINGS AGREE THAT THE ENVIRONMENT STILL LOOKS FAVORABLE FOR
STRONG TO SEVERE STORMS. WITH THE EXPECTED SUNSHINE...SHOULD SEE
SFC BASED CAPE GET IN THE 1000-1500 J/KG RANGE BY THIS AFTERNOON.
ADDITIONALLY...PLENTY OF 0-6 KM BULK SHEAR...GENERALLY 35-45 KT.
PLENTY OF MOISTURE AS WELL...WITH PRECIPITABLE WATER VALUES AROUND
1.25 INCHES...ABOVE CLIMATOLOGICAL NORMALS.
WITH A DECENT ENVIRONMENTAL SETUP...WILL JUST BE WAITING FOR THE
TRIGGER. LATEST WATER VAPOR INDICATING A SHORTWAVE TO THE
SOUTHWEST...WITH SOME ASSOCIATED CONVECTION OVER EASTERN KANSAS
AND WESTERN MISSOURI. TIMING OF THIS ACTIVITY TO THE SOUTHWEST
ALONG WITH LATEST HRRR AND LOCAL WRF4L MODEL INDICATE THE BEST
CHANCE FOR STORMS TO MOVE IN TODAY WILL BE IN THE DURING THE LATE
AFTERNOON AND EARLY EVENING HOURS.
&&
.AVIATION/18Z TAFS/...VFR CONDITIONS ARE EXPECTED TO CONTINUE
THROUGH TUESDAY...THOUGH LOWER CIGS/VSBYS POSSIBLE IN ANY
THUNDERSTORMS. BIG ISSUE THROUGH TOMORROW WILL BE TIMING ROUNDS OF
THUNDERSTORMS. LOOKS QUIET THIS MORNING...BUT WILL LIKELY SEE
STORMS DEVELOP THIS AFTERNOON OR EVENING...WITH STORMS THEN LIKELY
AT TIMES THROUGH TUESDAY.
&&
.PREV DISCUSSION... /ISSUED 329 AM CDT MON MAY 20 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.
ATMOSPHERE HAS BEEN STABILIZED SOMEWHAT BY OVERNIGHT CONVECTION BUT
LIKELY TO TURN UNSTABLE ONCE AGAIN LATER THIS MORNING AND AFTERNOON
DUE TO RETURNING SUNSHINE AND LINGERING HIGHER RELATIVE HUMIDITY.
PRECIPITABLE WATER VALUES CONTINUE AROUND 1.5 INCHES. UPPER JET
CONTINUES TO PIVOT SLOWLY EWD INTO WI TODAY RESULTING IN SOME
ENHANCED UPWARD VERTICAL MOTION. DIFFICULT TO DISCERN INDIVIDUAL
SHORT WAVES ROTATING AROUND UPPER LOW OVER THE PLAINS BUT ALL SHORT
TERM GUIDANCE CONTINUES TO INDICATE WEAK WAVES ROTATING AROUND
PARENT LOW INTO THE REGION THROUGH TONIGHT. LOW LEVEL JET WEAKENS
THIS MRNG BUT STRENGTHENS AGAIN THIS AFTERNOON AND EVENING. HENCE
WL CONTINUE CHANCE/SCATTERED LEVEL POPS THROUGH TODAY...AND BEEF UP TO
LIKELY WORDING FOR TONIGHT. AGGREGATE SEVERE PARAMETER INDEX REMAINS
HIGH FOR POTENTIAL SEVERE WEATHER LATE THIS AFTERNOON AND EVENING.
TUESDAY - CONFIDENCE...MEDIUM
UPPER LOW CONTINUES TO SPIN TO OUR WEST ACRS SE SD/NE NEB/SW MN/NW
IA. SRN WI WILL REMAIN SITUATED IN A SOUTHWEST UPPER FLOW WITH
SHORTWAVES MOVING THROUGH. 850 THERMAL RIDGE SHIFTS EAST. SYSTEM
OCCLUDES...BUT ENOUGH COLD AIR UPSTAIRS AND LINGERING LOW LEVEL
INSTABILITY TO KEEP THUNDERSTORM POTENTIAL HIGH. GFS AND NAM
SOUNDINGS ARE NOT SHOWING TREMENDOUS CAPE. 850 JET AXIS PLACES SE WI
IN FAVORABLE LEFT FRONT QUAD REGION AND 250 MILLIBAR JET ACROSS WI.
SLIGHT RISK STILL LOOKS OK AT THIS POINT.
WEDNESDAY - CONFIDENCE...MEDIUM
500 MILLIBAR FINALLY PLODS ACROSS THE AREA. NAM AND GFS REALLY CRANK
OUT THE QPF WITH SECONDARY SURFACE LOW THAT STRENGTHENS A BIT FROM
NRN IL INTO LOWER MI. ALL MODELS SUGGEST ENHANCED LOWER LEVEL
CONVERGENCE WITH 850 LOW/TROUGH. 00Z CAME IN WITH HIGHER QPF AMOUNTS
IN SRN WI...AGREEING WITH THE 00Z OUTPUT FROM THE NAM AND GFS. 12Z
ECMWF HAD THE BETTER QPF ACRS NRN WI. MODELS SUGGEST A BIT OF
LINGERING UPPER JET ACTION ACRS ERN WI MAINLY IN THE MORNING.
THURSDAY - CONFIDENCE...MEDIUM
LINGERING LOW LEVEL TROUGH KEEPS SHRA CHANCES AROUND...THOUGH HIGH
GRADUALLY BUILDS IN WITH TIME. NNE 850 FLOW DEVELOPS WITH COOL POOL
SETTLING IN.
FRIDAY - CONFIDENCE...MEDIUM
HIGH PRESSURE WILL DOMINATE. 12Z ECMWF SHOWS 3C AT 850 WHILE 00Z GFS
SHOWING 10C. EITHER WAY...LOOKING AT A QUIET DAY.
SATURDAY AND SUNDAY - CONFIDENCE...LOW
MODELS DIVERGING WITH TIMING/EVOLUTION OF WARM AIR ADVECTION/RIDGE
RIDER REGIME. BAROCLINIC ZONE POSITION IS IN QUESTION TOO. WILL LET
THE ALLBLEND POPS/TEMPS HANDLE THIS FOR NOW UNTIL MODELS COME INTO
BETTER AGREEMENT.
AVIATION/12Z TAFS/...POTENTIAL PERIOD OF LOW STRATUS IN WRN AREAS EARLY
THIS MRNG DUE TO BOUNDARY LAYER MIXING AND OVERNIGHT RAINFALL. OTHERWISE
EXPECT MOSTLY VFR CONDITIONS INTERRUPTED BY PASSING THUNDERSTORMS WITH
THE BEST CHANCE THIS AFTERNOON AND TONIGHT.
MARINE...WITH DEWPOINTS IN THE 60S LIKELY TO MOVE ACROSS THE NEARSHORE
WATERS...SOME PATCHY FOG AND HAZE LIKELY TO DEVELOP. COOLER WATERS
REMAIN TOWARD THE OPEN WATERS WITH SHALLOWER NEAR SHORE WATERS MORE
IN THE MIDDLE 50S TO AROUND 60. HENCE WL HOLD OFF ON INTRODUCING
DENSE FOG AT THIS TIME...BUT IS A CONCERN FARTHER AWAY FROM SHORE.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...DDV
TODAY/TONIGHT AND AVIATION/MARINE...MBK
TUESDAY THROUGH SUNDAY...COLLAR
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
659 AM CDT MON MAY 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT MON MAY 20 2013
MAIN FORECAST CONCERN IS ON SEVERE WEATHER AND FLOODING POTENTIAL
TODAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED AN UPPER LOW OVER SOUTH DAKOTA AND NEBRASKA WITH RIDGING
AHEAD OF IT OVER MICHIGAN. THE UPPER LOW WAS MOSTLY CUT OFF WITH
RIDGING TO ITS NORTH OVER SOUTH CENTRAL CANADA. 500MB STANDARD
DEVIATIONS WERE 1-1.5 BELOW NORMAL WITH THE UPPER LOW. NUMEROUS
SHORTWAVES WERE EJECTING IN SOUTHWEST FLOW AHEAD OF THE UPPER
LOW...SOME OF WHICH ARE CONVECTIVELY PRODUCED. ONE FOR EXAMPLE WAS
LIFTING THROUGH NORTHWEST WISCONSIN WHICH BROUGHT RAIN TO MUCH OF
THE AREA DURING THE NIGHTTIME HOURS. RAP DATA ALSO SHOWED A LOW
LEVEL MOISTURE TRANSPORT ZONE WITH THIS MCV. FARTHER SOUTH...ANOTHER
LOW LEVEL MOISTURE TRANSPORT ZONE WAS NOTED IN SOUTHERN MISSOURI...
POINTING INTO SOUTHERN ILLINOIS. COMBINATION OF SUBSIDENCE IN THE
WAKE OF THE MCV AND SPLIT IN MOISTURE TRANSPORT HAS ALLOWED THE
PRECIPITATION TO DIMINISH SOUTH OF HWY 29. PLENTIFUL MOISTURE COMING
UP AHEAD OF THE UPPER LOW WITH PRECIPITABLE WATER VALUES OF 1.2-1.5
INCHES FROM EASTERN OK INTO SOUTEHRN WI. THERE WAS A MINIMA OF
PRECIPITABLE WATER FROM WESTERN KS INTO MUCH OF IA...THOUGH....
ASSOCIATED WITH A DRY SLOT SOUTH OF THE UPPER LOW. AT THE
SURFACE...LOW PRESSURE WAS SITUATED UNDER THE UPPER LOW WITH A WARM
FRONT EXTENDING EAST TO EAU CLAIRE WI. RAP 850MB TEMPS WERE IN THE
14-18C RANGE SOUTH OF THE FRONT IN THE FORECAST AREA.
MODELS ARE IN GOOD AGREEMENT OF KEEPING THE UPPER LOW NEARLY
STATIONARY OVER SOUTH DAKOTA. DESPITE ITS STATIONARY MOVEMENT...THE
WEATHER WILL BE QUITE A BIT DIFFERENT COMPARED TO YESTERDAY.
PRIMARILY THIS IS DUE TO THE UPPER FLOW AHEAD OF THE UPPER LOW
PROGGED MORE SOUTHWESTERLY VERSUS SOUTHERLY. ADDITIONALLY...THE
PLUME OF HIGHER PRECIPITABLE WATER IS PROGGED TO SLOWLY SHIFT EAST
THANKS TO THE UPPER LOW.
MOST OF THE FORECAST AREA IS INDICATED TO STAY IN THE WARM SECTOR
THROUGH TONIGHT...ALONG WITH EXISTING IN THAT SOUTHWEST FLOW FOR
SHORTWAVES TO COME THROUGH...BOTH FAVORABLE FOR THUNDERSTORM
DEVELOPMENT. HOWEVER...ONE QUESTION MARK IS MOISTURE. BASED ON A
AMDAR SOUNDING OUT OF OMAHA AT 04Z...THE 850MB DEWPOINTS FROM THE
20.00Z NAM WERE 6-7C TOO HIGH...THUS THE NAM BUILDS A LOT OF CAPE
QUICKLY THIS MORNING. THE RAP IS MUCH MORE SUBDUED HAVING THE AREA
ENCOMPASSED BY THE DRY AIR...ESPECIALLY WHEN LOOKING AT MLCAPE.
THINKING THE RAP IDEA IS MUCH MORE REPRESENTATIVE AND HAVE KEPT THE
AREA DRY THROUGH EARLY AFTERNOON. EVENTUALLY...THE RAP DOES CATCH UP
WITH THE CAPE LATE IN THE AFTERNOON THANKS TO EVAPOTRANSPORATION OF
MOIST SOILS. IN FACT...THE RAP SHOWS A DEFINITIVE DRY LINE IN THE
WARM SECTOR FORMING NEAR I-35 IN THE AFTERNOON. THIS DRY LINE SHOULD
SERVE AS A TRIGGER FOR CONVECTIVE DEVELOPMENT...ESPECIALLY IN
SOUTHEAST MN AND NORTHEAST IA. MAJORITY OF MODELS...INCLUDING HI
RESOLUTION ONES...SHOW THIS SCENARIO...WITH THE THUNDERSTORMS THEN
PROPAGATING NORTHEAST THROUGH THE EVENING. THE BEST 0-6KM SHEAR OF
GREATER THAN 35 KTS IS PROGGED OVER THE SOUTHEAST HALF OF THE
FORECAST AREA...OPPOSITE OF WHERE MOST OF THE CONVECTION WILL BE. ON
THE OTHER HAND...FREEZING LEVEL HEIGHTS ARE LOWER ON THE ORDER OF
10500 FT WHERE THE CONVECTION IS EXPECTED...THUS THERE COULD END UP
BEING MARGINALLY SEVERE HAIL. STORMS SHOULD GRADUALLY WEAKEN AS
INSTABILITY WANES LATE IN THE EVENING INTO THE OVERNIGHT HOURS. IT
SHOULD BE NOTED...IF FOR SOME REASON A STORM FIRES IN THE HIGHER
0-6KM SHEAR AREA THIS AFTERNOON...IT WOULD LIKELY BECOME
SUPERCELLULAR. AGAIN...THOUGH...THINK THIS IS A LOW PROBABILITY WITH
THAT AREA PERHAPS EVEN BEING CAPPED. SEE THE HYDROLOGY SECTION BELOW
FOR FLOODING CONCERNS.
CERTAINTLY THE ADDITIONAL RAIN FROM STORMS THIS AFTERNOON AND EARLY
EVENING WILL NOT HELP THE FLOODING MATTERS IN PORTIONS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA. HAVE KEPT THE FLASH FLOOD WATCH GOING
TO 00Z THIS EVENING...WHICH WORKS OUT WELL IN TERMS OF TIME BECAUSE
THE CONVECTION SHOULD MOSTLY BE EAST OF THERE BY THE EXPIRATION.
SHOULD SEE QUITE A BIT OF SUN TODAY AND WITH 850MB TEMPS HOVERING IN
THAT 14-18C RANGE...TEMPERATURES SHOULD EASILY CLIMB INTO THE UPPER
70S TO MID 80S. ANOTHER MILD NIGHT LIKELY TONIGHT WITH PLENTY OF
CLOUDS AND DEWPOINTS REMAINING UP IN THE 50S TO LOW 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 341 AM CDT MON MAY 20 2013
TUESDAY THROUGH THURSDAY...
MAIN FOCUS HERE IS ON THE EVOLUTION OF THE UPPER LOW. 20.00Z
ECMWF/GFS/CANADIAN/NAM ARE ALL IN PRETTY GOOD AGREEMENT HOLDING THE
UPPER LOW NEARLY STATIONARY ON TUESDAY...THEN GRADUALLY SHIFTING
EASTWARD TUESDAY NIGHT AND WEDNESDAY BEFORE IT GETS MORE OF A KICK
EAST WEDNESDAY NIGHT. THE KICK EAST IS IN RESPONSE TO A POTENT
TROUGH DROPPING SOUTH THROUGH MUCH OF EASTERN CANADA.
FOR TUESDAY...MUCH OF THE FORECAST AREA WEST OF THE MISSISSIPPI
RIVER LOOKS TO BE DRY-SLOTTED...THUS HAVE LOWERED PRECIPITATION
CHANCES. TO THE EAST...THERE ARE INDICATIONS THAT SOME DIURNAL
CONVECTION COULD FORM ALONG A COLD FRONT MARCHING EAST. INSTABILITY
IS PRETTY MEAGER IN THIS CASE COMPARED TO WHAT WE HAVE BEEN DEALING
WITH...THUS ANY CONVECTION SHOULD NOT GO SEVERE. BETTER SHOT FOR
SEVERE WEATHER WILL BE WELL SOUTH AND EAST OF THE FORECAST AREA.
HIGHEST PRECIPITATION CHANCES OVERALL ARE EXPECTED NORTH OF HWY 29
IN A LOW TO MID LEVEL FRONTOGENESIS ZONE.
AS THE UPPER LOW BEGINS TO PUSH EAST TOWARDS THE FORECAST AREA
TUESDAY NIGHT AND WEDNESDAY...DPVA INCREASES WHILE SIMULTANEOUSLY
THE LOW TO MID LEVEL FRONTOGENESIS ZONE DROPS SOUTH. THEREFORE...
INCREASING PRECIPITATION CHANCES SEEM REASONABLE... ESPECIALLY ON
WEDNESDAY WHEN THE TWO FORCING MECHANISMS ARE JUXTAPOSTED.
ADDITIONALLY...THERE COULD BE SOME DIURNAL ENHANCEMENT ON WEDNESDAY
BEING CLOSE TO OR UNDER THE COLD CORE OF THE UPPER LOW.
MODELS APPEAR TO BE TRENDING FASTER IN KICKING OUT THE UPPER LOW FOR
WEDNESDAY NIGHT AND THURSDAY...ENOUGH SO THAT THURSDAY MAY NOW END
UP DRY. WEDNESDAY NIGHT STILL LOOKS FAVORABLE FOR PRECIPITATION...
ESPECIALLY EAST OF THE MISSISSIPPI RIVER WHICH IS IN THAT
AFOREMENTIONED JUXTAPOSITION OF FORCING MECHANISMS.
DEFINITELY A COOLING TREND WILL TAKE PLACE FOR TUESDAY THROUGH
THURSDAY WITH THAT UPPER LOW COMING IN...AND THEN COME THURSDAY A
NORTHERLY FLOW ADVECTING AIR FROM CANADIAN HIGH PRESSURE TRYING TO
BUILD SOUTH INTO THE UPPER GREAT LAKES. 850MB TEMPS FALL FROM 11-13C
AT 12Z TUE TO 4-6C BY 12Z THU. WENT WITH A BLEND OF GUIDANCE FOR
HIGHS AND LOWS FOR NOW GIVEN NO SIGNAL TO LEAN TOWARDS WARMER OR
COLDER SCENARIO GIVEN THE FORECAST PATTERN.
THURSDAY NIGHT INTO NEXT WEEKEND...
20.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES CONTINUE TO ADVERTISE A
BLOCKED UP UPPER LEVEL FLOW PATTERN ACROSS NORTH AMERICA DURING THE
EXTENDED PORTION OF THE FORECAST. THE FLOW FEATURES DEEP TROUGHING
ALONG THE WEST COAST...RIDGING FROM THE PLAINS INTO THE NORTHWEST
TERRITORIES...AND MEAN TROUGHING FROM EASTERN CANADA INTO THE
MID-ATLANTIC REGION. WHAT THIS PATTERN MEANS FOR THE FORECAST AREA
IS A BATTLE BETWEEN DRY...CANADIAN HIGH PRESSURE AND A MORE HUMID
AIRMASS ADVECTING NORTH OUT OF THE GULF OF MEXICO UNDER THE UPPER
RIDGE. IT APPEARS DRY CONDITIONS SHOULD PREVAIL FOR THURSDAY NIGHT
AND FRIDAY...RESULTING FROM SUBSIDENCE IN THE WAKE OF THE EARLY TO
MID WEEK UPPER LOW. FROM FRIDAY NIGHT AND BEYOND...HAVE FOLLOWED A
CONSENSUS APPROACH AND SPREAD PRECIPITATION CHANCES ACROSS THE
FORECAST AREA...HIGHEST WEST OF THE MISSISSIPPI RIVER. THESE CHANCES
ARE A RESULT OF SURGES OF WARM ADVECTION. THE PRECIPITATION COULD
BECOME ENHANCED TOO AT TIMES AS JET STREAKS PROPAGATE BETWEEN THE
EASTERN CANADA TROUGH AND PLAINS RIDGING.
SOMETHING TO WATCH DURING THE EXTENDED IS POTENTIAL FOR FROST...
ESPECIALLY IN CENTRAL WISCONSIN. THURSDAY NIGHT ACCORDING TO 20.00Z
MODELS WOULD BE THE HIGHEST CHANCE...THOUGH CONFIDENCE IS NOT HIGH
ENOUGH TO EITHER MENTION FROST IN THE FORECAST OR DROP LOWS BELOW
40. OTHERWISE...TEMPERATURES SHOULD STAY MOSTLY BELOW NORMAL BEING
UNDER THE INFLUENCE OF THE CANADIAN HIGH AND A NORTHEAST FLOW.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 658 AM CDT MON MAY 20 2013
THE MVFR CEILINGS ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA WILL
GRADUALLY MIX OUT THIS MORNING. THIS SHOULD OCCUR AT KRST AROUND
20.15Z.
STEEP LOW LEVEL LAPSE RATES WILL KEEP WIND GUSTS IN THE 20 TO 30
KNOT RANGE THROUGHOUT THE DAY.
FOR THIS AFTERNOON AND EVENING...A TROUGH...LOCATED OVER KANSAS...WILL
MOVE NORTHEAST THROUGH THE AREA. AS THIS OCCURS...EXPECTY RAPID
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS THE AREA BETWEEN
20.21Z AND 21.00Z. THE 0-3KM WINDS ARE FAVORABLE FOR THE THUNDERSTORMS
TO PRODUCE DAMAGING WINDS. IN ADDITION...THERE WILL BE ENOUGH
INSTABILITY FOR LARGE HAIL.
AS THE TROUGH MOVES NORTHEAST OF THE AREA AFTER 21.06Z...EXPECT A
BROKEN DECK OF 8-10K CEILING TO LINGER ACROSS THE AREA THROUGH THE
REMAINDER OF THE NIGHT.
&&
.HYDROLOGY...
ISSUED AT 341 AM CDT MON MAY 20 2013
MULTIPLE DAYS OF HEAVY RAIN ACROSS PORTIONS OF SOUTHEAST MINNESOTA
AND NORTHEAST IOWA HAS REALLY LOWERED THE THRESHOLD FOR FLOODING. A
STRIPE FROM MITCHELL COUNTY IA THROUGH MOWER...WESTERN FILLMORE AND
OLMSTED COUNTIES WERE ESPECIALLY HARD HIT FROM YESTERDAYS RAIN.
REPORT FROM MITCHELL COUNTY IA EMERGENCY MANAGER AT 330 AM WAS THAT
MOST MAIN ROADS ARE CLOSED DUE TO HIGH WATER AND MANY SIDE ROADS ARE
WASHED OUT. THUS...THE AREA THAT WAS PUT IN A FLASH FLOOD WATCH
YESTERDAY CANNOT HANDLE ANY MORE RAIN. SEE LATEST AREAL AND RIVER
FLOOD STATEMENTS FOR MORE INFORMATION.
ON A POSITIVE NOTE...THE DEEP MOISTURE THAT WAS PRESENT TO ALLOW THE
STORMS TO PRODUCE SUCH HEAVY RAIN IS SHIFTING OFF TO THE EAST.
ADDITIONALLY...EVEN THOUGH SOME THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON...THERE LOOKS TO BE ENOUGH UPPER LEVEL FLOW TO KEEP THEM
MOVING TO THE EAST. THUS...NOT ANTICIPATING ANY WIDESPREAD FLOODING.
WILL NEED TO KEEP THE FLASH FLOOD WATCH GOING...THOUGH...BECAUSE AS
MENTIONED EARLIER THE AREA HAS BEEN SO HARD HIT ANY RAIN WILL CAUSE
A PROBLEM.
ADDITIONAL RAINFALL IS POSSIBLE TUESDAY THROUGH WEDNESDAY
NIGHT...THOUGH TUESDAY IS TRENDING DRIER FOR SOUTHEAST MINNESOTA AND
NORTHEAST IOWA. HOPEFULLY THE DRIER PERIOD FROM TONIGHT THROUGH
TUESDAY WILL ALLOW THE FLOOD THREAT TO DIMINISH...THOUGH RIVER
FLOODING MAY TAKE A LITTLE LONGER TO END.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH THIS EVENING FOR MNZ079-086-087-094-
095.
IA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR IAZ008.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...BOYNE
HYDROLOGY...AJ
AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
1157 AM CDT MON MAY 20 2013
.AVIATION...
SCATTERED HIGH END MVFR CIGS ACROSS CENTRAL AND WEST SECTIONS
SHOULD CLIMB ABOVE THE MVFR THRESHOLD BY 21Z. TSRA CHANCES WILL
INCREASE FROM WEST TO EAST THROUGH THE PERIOD.
55
&&
.PREV DISCUSSION... /ISSUED 1039 AM CDT MON MAY 20 2013/
UPDATE...
MADE SOME CHANGES TO THE FORECAST FOR TODAY. A LOOK AT THE MORNING
SOUNDING REVEALS A VERY UNSTABLE ATMOSPHERE WITH A RATHER
SIGNIFICANT CAP AROUND 850 MB. IN SPITE OF THAT THERE IS ABUNDANT
MOISTURE PRESENT AND I FELT IT WOULD BE PRUDENT TO INTRODUCE SOME
RELATIVELY LOW POPS FURTHER TO THE SOUTH ACROSS THE CWA TODAY. IN
ADDITION...CLOUD COVER IS A BIT MORE EXTENSIVE THAN PREVIOUSLY
FORECAST AND IT LOOKS LIKE WE WILL CONTINUE TO HAVE MORE THAN
FORECAST FOR THE REST OF THE DAY...SO I UPPED THOSE VALUES AS WELL.
GETTING BACK TO THE ISSUE OF THE UNSTABLE SOUNDING...THE MODELS
ARE HAVING SOME DIFFICULTIES WITH HOW TO HANDLE THE TIMING OF
STORMS THIS AFTERNOON AND TONIGHT. THE ATMOSPHERE IS QUITE
UNSTABLE...SFC BASED CAPE VALUES ARE ABOVE 3000 J/KG IN CENTRAL
ARKANSAS THIS MORNING AND THE HODOGRAPH IS A BIT OMINOUS. I AM
CONCERNED ABOUT THE POTENTIAL FOR THE DEVELOPMENT OF DISCRETE
SUPERCELLS LATER THIS AFTERNOON AND EVENING ACROSS THE NWRN
PORTIONS OF THE FORECAST AREA. WE WILL BE CONDUCTING A SPECIAL
SOUNDING AT 18Z TODAY TO ASSESS HOW THINGS HAVE CHANGED BY MIDDAY.
CONVECTION THAT WAS OCCURRING ACROSS THE NORTHERN PART OF THE
STATE EARLIER THIS MORNING HAS FIZZLED OUT AND WITH THE EXCEPTION
OF CONVECTION ACROSS WESTERN MO...NOT MUCH ELSE IS HAPPENING THIS
MORNING. I CANT HELP BUT WONDER IF UPPER LEVEL JET DYNAMICS ARE
PLAYING A SUPRESSING ROLE THIS MORNING AS SOME MODELS ARE IMPLYING
A JET MAX EXITING OVER NW MO THIS MORNING WITH ANOTHER SPEED MAX
OVER NRN OK THIS MORNING SWINGING AROUND. IF THAT HOLDS UP THE LID
COULD START TO COME OFF THE CONVECTION BY EARLY TO MID AFTERNOON
ACROSS THE NW. 53
PREV DISCUSSION... /ISSUED 620 AM CDT MON MAY 20 2013/
DISCUSSION...
UPDATED TO INCLUDE THE 12Z AVIATION DISCUSSION BELOW...
AVIATION...
A LINE OF SHRA/TSRA IS EXTENDING FROM MO INTO NORTH CENTRAL AR
THIS MORNING...WITH VCTS CONTINUING IN THE TAF FOR THE NRN SITES
THIS MORNING. OTHERWISE...SOME SITES WERE SEEING SOME MVFR
CIGS...WHICH SHOULD IMPROVE TO VFR LEVELS OUTSIDE ANY PRECIP
ACTIVITY LATER THIS MORNING. ALSO...SOME AREAS EARLY IN THE PERIOD
COULD SEE A BIT OF LOW END LLWS...BUT SHOULD IMPROVE AS SFC WINDS
INCREASE LATER THIS MORNING. BREEZY SRLY WINDS WILL BE SEEN TROUGH
THIS AFTERNOON AND EARLY EVENING AS SFC PRESSURE GRADIENT REMAINS
FAIRLY TIGHT ACROSS THE REGION. HAVE MENTIONED VCTS ACROSS THE NRN
SITES THROUGH THIS AFTERNOON AS ADDITIONAL TSRA COULD DEVELOP THIS
AFTERNOON. THIS EVENING AND INTO TUE MORNING...THE POTENTIAL FOR
SHRA/TSRA WILL SPREAD FURTHER SOUTH AND EAST...WITH PROB30 OR VCTS
MENTIONED FOR TSRA POTENTIAL DURING THIS PERIOD OF THE TAF. SOME
MVFR OR LOWER CONDITIONS COULD BE SEEN UNDER THE PRECIP ACTIVITY.
PREV DISCUSSION... /ISSUED 410 AM CDT MON MAY 20 2013/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
STORMS FORMED OVER NORTHEAST OKLAHOMA LATE SUNDAY EVENING...AND
MOVED NORTHEAST INTO SOUTHERN MISSOURI OVERNIGHT. HOWEVER...SHOWERS
HAVE RECENTLY DEVELOPED ALONG THE SOUTHERN EDGE AND ARE MOVING INTO
NORTHERN ARKANSAS. HAVE KEPT SMALL RAIN CHANCES ACROSS THE NORTH
THROUGH THE MORNING HOURS...AS MUCH OF THIS ACTIVITY WILL DISSIPATE
BEFORE NOON.
QUESTION FOR THIS AFTERNOON WILL BE IF ANY DEVELOPMENT OCCURS ON ANY
LINGERING BOUNDARIES LEFT OVER FROM THE OVERNIGHT ACTIVITY. THE NAM
AND NOW THE HRRR IS PICKING UP ON THIS...AHEAD OF ACTIVITY
DEVELOPING OFF LOW LEVEL JET AROUND SUNSET. THIS WILL HAVE TO BE
MONITORED CLOSELY...BECAUSE IF ANY CELL IS DISCRETE...SEVERE WEATHER
WILL BE MAXIMIZED.
THIS EVENING...STORMS WILL FORM ACROSS EASTERN OKLAHOMA INTO
SOUTHERN MISSOURI...AS FRONT INTERACTS WITH LOW LEVEL JET. THE
STORMS WILL SLOWLY MOVE EAST DURING THE LATE EVENING INTO THE
OVERNIGHT HOURS...WITH STRONG TO SEVERE STORMS POSSIBLE. ALSO...WITH
THE SLOW MOTION AND COPIOUS AMOUNTS OF MOISTURE...HEAVY RAINFALL IS
POSSIBLE...ESPECIALLY ACROSS THE NORTHWEST HALF OF THE STATE TONIGHT.
THE FRONT WILL PROGRESS INTO THE STATE TUESDAY...WITH SEVERE
POTENTIAL CONTINUING. HOWEVER...TORNADIC POTENTIAL WILL NOT BE AS
GREAT DUE TO LESSENING SHEAR. FLOODING REMAINS A CONCERN FOR
TUESDAY...AS SEVERAL ROUNDS OF THUNDERSTORMS WILL MOVE ACROSS THE
AREA.
THE RAINFALL WILL BEGIN TO MOVE SOUTHEAST LATE TUESDAY INTO TUESDAY
NIGHT...WITH MUCH OF THE ACTIVITY CONFINED TO THE SOUTHEAST HALF OF
THE STATE WEDNESDAY. HOWEVER...THE FRONT WILL MEANDER AROUND THE
AREA THROUGH THE END OF THE SHORT TERM...WITH SMALL RAIN CHANCES
CONTINUING.
LONG TERM...FRIDAY THROUGH SUNDAY
COLD FRONT WILL HAVE PUSHED INTO THE STATE FROM THE NE AT THE START
OF THE LONG TERM PERIOD...STALLING ACROSS THE STATE FROM NW TO SE.
MENTION SLIGHT CHANCE POPS WITH THIS FRONT OVER THE STATE FOR
FRI...BUT AN UPPER RIDGE TO THE WEST WILL BEGIN TO SHIFT EAST OVER
THE SRN PLAINS AND SRN MS RIVER VALLEY REGION INTO THIS WEEKEND. AS
A RESULT OF THE RIDGING ALOFT...DECREASE POPS INTO THE WEEKEND...AS
WELL AS INCREASING TEMPS ABOVE NORMAL BY LATE IN THE FORECAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
BATESVILLE AR 85 69 80 65 / 20 50 60 80
CAMDEN AR 89 70 87 67 / 10 20 50 70
HARRISON AR 82 66 78 60 / 40 80 70 60
HOT SPRINGS AR 88 71 84 67 / 20 40 60 70
LITTLE ROCK AR 88 70 84 68 / 20 40 60 70
MONTICELLO AR 90 72 88 69 / 10 20 40 60
MOUNT IDA AR 87 70 83 64 / 20 50 60 70
MOUNTAIN HOME AR 83 67 77 61 / 30 80 60 70
NEWPORT AR 87 70 82 67 / 20 40 60 80
PINE BLUFF AR 89 71 86 69 / 10 20 50 70
RUSSELLVILLE AR 85 68 80 63 / 20 60 60 70
SEARCY AR 87 69 82 66 / 20 40 60 70
STUTTGART AR 89 71 85 68 / 10 30 50 70
&&
.LZK WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AVIATION...99
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
308 PM EDT Mon May 20 2013
.NEAR TERM [through tonight]...
The 16 UTC mesoanalysis showed a very weak pressure/wind field
across our forecast area, much like a typical day in the middle of
summer. There were no obvious mesoscale boundaries, but visible
satellite imagery continued to show a cyclonic "twist" near
Tallahassee- probably associated with an MCV from Sunday`s
thunderstorm complex. Vapor imagery and upper air data showed a weak
trough from VA through North FL, with much of our forecast area
under northerly flow aloft on the backside of this trough.
The large scale environment, GFS MOS PoP, and some of the Convection
Allowing Model (CAM) runs suggest that the highest rain chances will
be over our eastern zones, while some of the CAM (like the HRRR and
11 UTC & 12 UTC local WRF runs) continue to forecast scattered
storms across a large portion of our forecast late this afternoon
and evening. The answer is assumed to be somewhere in between,
except that the CAM guidance often has a tendency to be a few hours
late in developing convective cells. Our PoP is 30-40% for most of
our forecast area for the remainder of this afternoon and early
evening. The spatial distribution matches well with the best
thermodynamics, which are most favorable in GA. Although the wind
field is very weak (from the surface to 500 mb), there could be a
few pulse strong to severe storms this afternoon due to the steep
lapse rates. The main threat...though small...will be dime to
quarter size hail and/or microbursts of 50-60 MPH.
&&
.SHORT TERM [Tuesday Through Thursday]...
Slow moving mid level low pressure area will transition into a low
amplitude trough as it shifts slowly ewd across the southeastern
U.S. over the next several days. This will keep unsettled weather
around into at least Thursday with a chance of afternoon showers
and thunderstorms. Rain chances will be a bit greater over our
eastern counties where moisture will be more plentiful. Clouds
and residual outflow boundaries may make afternoon highs a bit
tricky to forecast, however in general expect similar temperatures from
today with highs in the upper 80s to lower 90s and overnight lows
in the 60s. A few stronger storms can not be ruled out each
afternoon, although overall severe threat will remain fairly low.
&&
.LONG TERM [Thursday Night through Monday]...
Unsettled weather pattern will continue into the late part of the
week, but will replaced by drier weather for the weekend as a
slow moving trough finally shifts away from the area. A mid/upper
level ridge of high pressure will begin to establish itself over
the area for the holiday weekend into next week which should
preclude more than isolated afternoon showers/tstms. Temperatures
are expected to remain seasonal with highs in the upper 80s/lower
90s and overnight lows in the 60s.
&&
.AVIATION [through 18Z UTC Tuesday]...
Isolated to scattered TSRA will develop this afternoon, mainly
from 19 UTC through 01 UTC, and mainly around KABY and KVLD where
the probability of rain is 40%. A few storms could produce strong
to severe wind gusts and/or marginally severe hail. The
probability of TSRA elsewhere is 30% or less. Outside of TSRA, VFR
vis and cigs are expected. Patchy fog and/or low clouds are
possible for a brief time Tuesday morning, though confidence is
not high enough to explicitly mention in this TAF package.
&&
.FIRE WEATHER...
Red Flag conditions are not expected for the next several days, as
minimum RH values will likely remain above locally critical levels.
&&
.MARINE...
Pleasant weather and seas will remain the norm through the weekend
with light winds.
&&
.HYDROLOGY...
Unsettled weather pattern will continue into the late week and
support scattered, slow moving thunderstorms each afternoon.
Although some localized flooding could occur with the heavier
storms, overall impacts should remain minor and no meaningful rise
is expected along area rivers.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 67 90 66 89 67 / 30 20 10 40 20
Panama City 70 84 69 83 70 / 20 20 10 20 20
Dothan 68 92 68 92 68 / 30 20 10 30 20
Albany 69 91 69 90 68 / 30 20 30 40 20
Valdosta 66 88 66 87 66 / 30 30 30 50 20
Cross City 66 89 65 87 64 / 30 40 30 40 20
Apalachicola 69 82 68 82 69 / 20 20 10 20 20
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
SHORT TERM/LONG TERM/MARINE/HYDROLOGY...Evans
REST OF DISCUSSION...Fournier
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
132 PM EDT MON MAY 20 2013
.SHORT TERM /TODAY THROUGH TUESDAY NIGHT/...
/ISSUED AT 328 AM EDT MON MAY 20 2013/
THE IMMEDIATE SHORT TERM WILL BE SPENT DEALING WITH RESULTS OF A
NEARLY 24 HOUR LONG RAINFALL EVENT WHICH INCLUDES THE DEVELOPMENT
OF LOW CLOUDS AND FOG. GENESIS REGION FOR THIS IS THE CAROLINAS
AND OVER THE LAST SEVERAL HOURS HAS SPREAD WEST INTO THE NORTHEAST
MOUNTAINS AND JUST NOW ENTERING INTO THE REMAINDER OF NORTH
GEORGIA. NAM12 VERY BULLISH ON FOG DEVELOPMENT THROUGH THIS
MORNING WITH WIDESPREAD CONDENSATION PRESSURE DEFICIT VALUES RIGHT
AROUND ZERO. GFS NOT NEARLY THIS AGGRESSIVE BUT BASED ON
OBS...LOOKS LIKE NAM12 IS INITIALIZING BETTER AT THIS POINT AND
WILL FAVOR ITS SOLUTION.
FOG AND LOW CLOUDS TO SLOWLY LIFT DURING THE MORNING HOURS BUT
ENOUGH LOW LEVEL MOISTURE REMAINS TO MAINTAIN A CIG DECK FOR MUCH
OF THE DAY. AS FAR AS POPS AREA CONCERNED...MODELS IN AGREEMENT
THAT UPPER RIDGE AXIS WILL SHIFT EASTWARD...GETTING US OUT OF THE
BELT OF NW FLOW AND LIMITING EFFECTS FROM ANY IMPULSES TO OUR
EXTREME EASTERN SECTIONS. AM A LITTLE CONCERNED THAT WEAK SYNOPTIC
WINS WILL ALLOW SEA BREEZE AND DEVELOPING OUTFLOWS PROPAGATE WEST
AND BRING SHOWERS AND THUNDERSTORMS WITH THEM SO HAVE GONE ABOVE
GUIDANCE FORM MY SOUTHEAST ZONES TODAY. HRRR SHOWS SEPARATE
SECTION DEVELOPING DURING THE AFTERNOON. ALTHOUGH THIS REGION IS
CLOSER TO UPPER RIDGE...STRENGTH OF THIS FEATURE IS LIMITED AND
WILL NEED TO CARRY AT LEAST SLIGHT CHANCE POPS ALL ZONES.
LOW CLODS AND FOG NOT QUITE AS PROMINENT IN THE MODELS TUESDAY
MORNING BUT SATELLITE LOOKS LIKE DECENT DEVELOPMENT OVER THE EASTERN
THIRD OF THE REGION...ESPECIALLY THE NORTHEAST MOUNTAINS. THIS
WILL GIVE WAY ONCE AGAIN TO IMPROVING SKY CONDITIONS BY AFTERNOON
BUT POPS LOOK TO BE ON THE INCREASE AGAIN. UPPER RIDGE AXIS
WEAKENS SLIGHTLY IN RESPONSE TO APPROACHING TROUGH.
MEANWHILE...LOW LEVEL INSTABILITY AND LAPSE RATES WILL BE ON THE
INCREASE WITH CAPE VALUES OF NEAR 3000 J/KG PROJECTED LATE
TUESDAY. GIVEN FLOW PATTERN...WOULD EXPECT DEVELOPMENT OVER THE NE
MOUNTAINS FIRST AND THEN PROPAGATING SW TOWARD THE ATLANTA METRO.
HAVE GONE A CONSIDERABLE AMOUNT ABOVE GUIDANCE FOR THESE AREAS.
DEESE
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
/ISSUED AT 328 AM EDT MON MAY 20 2013/
UPPER LEVEL TROUGH APPROACHING ON WEDNESDAY AND COMBINED WITH
ASSOCIATED MOIST AND INSTABILITY WILL GIVE POTENTIAL FOR NUMEROUS
SHOWERS AND SCATTERED THUNDERSTORMS ACROSS MAINLY N GA AND MAINLY
SCATTERED SHOWERS AND STORMS FOR CENTRAL GA. A WEAK COLD FRONT GETS
INTO THE AREA LATE THURSDAY...POSSIBILITY ASSOCIATED WITH SOME UPPER
LEVEL SUPPORT...WILL GIVE THE CHANCE FOR SHOWERS AND STORMS. BEST
MOISTURE AND UPPER SUPPORT DRIFTING EAST ON FRIDAY ALLOWING FOR ONLY
A SLIGHT CHANCE OF SHOWERS AND STORMS. OVERALL MOISTURE AND
INSTABILITY APPEAR LACKING SATURDAY INTO MONDAY AND WHILE PRECIP
POTENTIAL IS NOT ZERO IT LOOKS TO BE LESS THAN 20 PERCENT AT THIS
TIME. TEMPERATURES RUNNING WITHIN 5 DEGREES OF NORMAL THROUGH THE
PERIOD.
BDL
&&
.AVIATION...18Z UPDATE...
MOST CIGS HAVE GONE VFR. A BROKEN DECK MOVING INTO THE ATL AREA
SHOULD RISE ABOVE 3000 BY 18Z AND REMAIN VFR THROUGH THE AFTERNOON.
EXPECT SCATTERED CONVECTION SOUTH OF THE FALL LINE THIS AFTERNOON
BUT THIS SHOULD DISSIPATE AFTER SUNSET. IFR/MVFR CIGS TO REDEVELOP
LATE TONIGHT ACROSS MUCH OF THE AREA WITH 2-5SM WITH FOG. THIS
SHOULD DISSIPATE DURING THE MORNING. WINDS WILL REMAIN LIGHT WITH A
SOUTHWEST COMPONENT FROM CSG-ATL-AHN WHILE MCN HOLDS ON TO A SOUTH
TO SOUTH SOUTH EAST WIND. ALL AREAS GOING NEAR CALM TONIGHT AND THEN
SOUTHWEST AGAIN ON TUESDAY.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM ON CIGS THIS AFTERNOON AND AFTER 09Z TUE.
HIGH ON REMAINING ELEMENTS.
17
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 84 65 86 64 / 20 5 40 40
ATLANTA 85 68 86 67 / 20 5 30 30
BLAIRSVILLE 82 58 83 63 / 20 5 30 30
CARTERSVILLE 86 65 87 66 / 20 5 20 20
COLUMBUS 88 67 89 67 / 20 10 20 20
GAINESVILLE 83 65 85 66 / 20 5 40 40
MACON 86 64 88 64 / 30 5 30 30
ROME 87 65 88 66 / 20 5 20 20
PEACHTREE CITY 86 62 87 63 / 20 5 30 30
VIDALIA 85 66 87 69 / 40 20 30 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...DEESE
LONG TERM....BDL
AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS LINCOLN IL
222 PM CDT MON MAY 20 2013
.DISCUSSION...
ISSUED 222 PM CDT MON MAY 20 2013
SEVERE WEATHER CHANCES CONTINUE TO BE THE MAIN FOCUS...WITH RAIN
CHANCES LINGERING THROUGH THURSDAY. A COOLING TREND WILL DEVELOP
MID WEEK WITH BELOW NORMAL TEMPS FOR LATE WEEK AND INTO THE
WEEKEND.
SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT.
THE ATMOSPHERE STARTED OUT THE AFTERNOON A BIT MORE STABLE THAN
MODEL GUIDANCE HAD INDICATED. MUCAPE VALUES ARE IN AROUND 500 J/KG
WITH SOME CONVECTIVE INHIBITION OF 150-200 J/KG. SFC DEWPOINTS AND TEMPS
ARE ON THE RISE AND INCREASING MID LEVEL JET WINDS TO THE
SOUTHWEST SHOULD STILL TO NOSE INTO CENTRAL ILLINOIS BY EVENING.
THE ONSET OF SEVERE STORMS MAY BE SLIGHTLY DELAYED DUE TO THE TIME
IT WILL TAKE FOR THE INGREDIENTS FOR STORMS TO DEVELOP. THE
EVOLUTION SHOULD BE FOR DISCREET SUPERCELLS FORMING IN MISSOURI
AND ADVANCING EAST ALONG THE AXIS OF INSTABILITY FROM SW TO NE.
THE DIRECTIONAL SHEAR IN THE PLAINS WILL EVOLVE TO MORE
UNIDIRECTIONAL SHEAR ACROSS CENTRAL IL. THAT WILL HELP THE
SUPERCELLS TO EVOLVE INTO MORE OF A LINEAR SETUP, WITH STRAIGHT-
LINE AND DOWNBURST WINDS MORE LIKELY. EMBEDDED SUPERCELLS WILL
STILL BE POSSIBLE DUE TO AMBIENT VORTICITY NEAR PRE-EXISTING
CONVECTIVE BOUNDARIES ALL OVER CENTRAL ILLINOIS.
THE EVENING HOURS LOOK TO BE OUR PRIMARY SEVERE WINDOW...WITH A
DOWNWARD TREND IN SEVERE AFTER MIDNIGHT AS THE STORMS HEAD INTO
OUR EASTERN COUNTIES. THE 4KM HRRR IS DEPICTING THE NW HALF OF OUR
AREA TO HAVE THE BEST CHANCES FOR STORMS...WITH LINEAR STORM
SEGMENTS DEVELOPING AFTER MIDNIGHT IN THE SOUTHEAST HALF...AND A
MORE ISOLATED SEVERE THREAT BUT STILL PRESENT.
THE SEVERE POTENTIAL ON TUESDAY WILL BE TIED TO THE ADVANCEMENT OF
A 500 MB SHORTWAVE AND RESULTANT SURFACE CYCLOGENESIS FROM THE
SOUTHERN PLAINS ACROSS CENTRAL IL. THE PRIMARY FORCING FOR STORMS
LOOKS TO HOLD OFF UNTIL TUESDAY EVENING...WHEN THE WAVE WILL MOVES
INTO WESTERN IL. STORMS ARE EXPECTED TO ERUPT ACROSS EASTERN MO
AND SW IL IN THE EVENING AND PROGRESS TO THE E-NE OVERNIGHT. WE
SEVERE POTENTIAL SHOULD BE HIGHER SOUTHEAST OF I-55...BASED ON THE
TRACK OF THE SURFACE LOW AND LOCATION OF THE 850 MB LLJ.
STORMS SHOULD BE PRIMARY EAST OF OUR AREA BY SUNRISE
WEDNESDAY...BUT ADDITIONAL SHOWERS AND A FEW STORMS WILL BE
POSSIBLE AS COLD AIR ADVANCES INTO IL. VARIOUS SHORTWAVES WILL BE
ROTATING ACROSS ILLINOIS AS THE UPPER TROUGH AXIS MOVES INTO
WESTERN IL.
LONG TERM...THURSDAY THROUGH MONDAY.
ON THURSDAY...THE SLOW MOVEMENT OF THE UPPER LEVEL AND SURFACE
LOWS FROM THE NORTHERN PLAINS ACROSS THE GREAT LAKES WILL CAUSE
SHOWERS TO LINGER ACROSS CENTRAL IL. THE AXIS OF THE ELEVATED COLD
POOL ALOFT WILL PASS ACROSS IL AROUND MID-DAY THURSDAY. LAPSE
RATES APPEAR FAVORABLE FOR SOME INSTABILITY SHOWERS TO DEVELOP IN
THE HEAT OF THE DAY...WITH A LITTLE HELP FROM CHANNELED VORTICITY
IN THE LEE SIDE OF THE UPPER TROUGH.
CLEARING SKIES THURSDAY NIGHT WILL ALLOW LOWS TO DIP INTO THE
UPPER 40S NORTH OF A LINE FROM RUSHVILLE TO LINCOLN TO CHAMPAIGN.
DESPITE SUNSHINE ON FRIDAY...HIGH TEMPS WILL STRUGGLE TO REACH
AROUND 70 IN MOST OF THE AREA.
THE 00Z/20 ECMWF HAD A WET HOLIDAY WEEKEND FORECAST...WITH A DRY
FORECAST FROM THE 00Z/GFS. THEY APPEAR TO HAVE FLIP-FLOPPED THE
FORECAST WITH THE 12Z VERSIONS. THE 12Z GFS NOW SHOWING RAIN
CHANCES LATE SATURDAY THROUGH MEMORIAL DAY. THE ECMWF STILL HAS
SOME RAIN LATE FRI NIGHT INTO SATURDAY...BUT DRY CONDITIONS FOR
SUNDAY AND MEMORIAL DAY. THE ALLBLEND HAS BASICALLY KEPT SOME
MENTION OF RAIN DUE TO THE PRESENT SIGNAL FROM AT LEAST ONE MODEL
EACH DAY OF THE WEEKEND. THE MAIN THEME REMAINS THAT A WAVE OF
ENERGY IS FORECAST TO EXIT THE PLAINS EARLY IN THE WEEKEND BUT
WHERE THE FRONT STALLS OUT FOR LINGERING RAIN REMAINS TO BE SEEN.
SHIMON
&&
.AVIATION...
ISSUED 1246 PM CDT MON MAY 20 2013
CLUSTER OF THUNDERSTORMS CURRENTLY CROSSING THE MISSISSIPPI RIVER
JUST SOUTH OF QUINCY WILL TRACK E/NE INTO THE AREA EARLY THIS
AFTERNOON. AIRMASS IS BEGINNING TO DESTABILIZE IN ADVANCE OF THIS
CONVECTION...SO CONFIDENCE IS GROWING THAT IT WILL HOLD TOGETHER
AND ARRIVE AT KSPI BETWEEN 19Z AND 21Z. ITS EVOLUTION BEYOND THAT
STILL REMAINS IN QUESTION...SO WILL ONLY CARRY VCTS AFTER 21Z AT
THE REMAINING TERMINALS. OUTSIDE OF ANY CONVECTION THAT DEVELOPS
THIS AFTERNOON...STRONG SOUTHERLY WINDS WILL GUST TO BETWEEN 25
AND 30KT. MODELS DISAGREE ABOUT THE TIMING/PLACEMENT OF ADDITIONAL
CONVECTION LATER TODAY AND TONIGHT...HOWEVER THE HRRR CONTINUES TO
FOCUS THE MOST WIDESPREAD STORMS DURING THE EVENING INTO THE
OVERNIGHT HOURS. WILL THEREFORE KEEP TEMPO GROUPS FOR THUNDER
BETWEEN 02Z AND 06Z AT KPIA AND BETWEEN 04Z AND 08Z FURTHER EAST
AT KCMI. AFTER THAT...MID-LEVEL DRYING IN THE WAKE OF THE
OVERNIGHT CONVECTION WILL LEAD TO A DRY TUESDAY MORNING.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1246 PM CDT MON MAY 20 2013
.DISCUSSION...
ISSUED 1041 AM CDT MON MAY 20 2013
AIRMASS HAS TEMPORARILY STABILIZED ACROSS CENTRAL ILLINOIS THIS
MORNING...THANKS TO OVERNIGHT CONVECTION THAT HAS PUSHED THE MAIN
OUTFLOW BOUNDARY TO A LAFAYETTE INDIANA TO FLORA ILLINOIS LINE.
15Z/10AM LAPS DATA SHOWS SBCAPE VALUES OF LESS THAN 500J/KG
BEHIND THE BOUNDARY...WITH VALUES IN EXCESS OF 2000J/KG AHEAD OF
THE BOUNDARY ACROSS THE FAR SE KILX CWA. FORECAST SOUNDINGS SHOW
AIRMASS GRADUALLY DESTABILIZING BY THIS AFTERNOON...HOWEVER
HIGHEST DEWPOINTS AND SUBSEQUENT CAPE VALUES WILL BE FOCUSED
FURTHER SOUTHEAST OVER THE OHIO RIVER VALLEY. NEVERTHELESS...CAPES
OF 1500 TO 2500J/KG SHOULD BE REALIZED ACROSS MUCH OF THE AREA
LATER TODAY. IN ADDITION...STRONG LOW-LEVEL SHEAR WILL BE IN
PLACE ACROSS THE WESTERN HALF OF THE CWA...WITH 0-6KM BULK SHEAR
VALUES RANGING FROM 45 TO 55KT. COMBINATION OF MODEST INSTABILITY
AND STRONG SHEAR WILL BE ENOUGH TO SUPPORT THE DEVELOPMENT OF
STRONG TO SEVERE THUNDERSTORMS LATE THIS AFTERNOON INTO THE
EVENING. HIGH-RES MODELS SUCH AS THE NAM12 AND 4KM HRRR SUGGEST
CONVECTION WILL FIRE ALONG ANOTHER BOUNDARY STRETCHING FROM
EASTERN KANSAS INTO WEST-CENTRAL ILLINOIS AFTER 19Z/2PM. INITIAL
CONVECTIVE MODE WILL BE SUPPORTIVE OF SUPERCELLS THIS AFTERNOON/EARLY
EVENING...BEFORE STORMS BECOME MORE LINEAR BY MID EVENING AS THEY
TRACK FROM SW TO NE ACROSS THE AREA. HAVE MODIFIED POPS/TEMPS JUST
A BIT FOR THE REMAINDER OF THE DAY...BUT CHANGES DO NOT
SIGNIFICANTLY IMPACT GOING FORECAST. CHANCE SHOWERS/STORMS THIS
MORNING...WITH LIKELY POPS ARRIVING ALONG/WEST OF I-55 BY MID TO
LATE AFTERNOON.
&&
.AVIATION...
ISSUED 1246 PM CDT MON MAY 20 2013
CLUSTER OF THUNDERSTORMS CURRENTLY CROSSING THE MISSISSIPPI RIVER
JUST SOUTH OF QUINCY WILL TRACK E/NE INTO THE AREA EARLY THIS
AFTERNOON. AIRMASS IS BEGINNING TO DESTABILIZE IN ADVANCE OF THIS
CONVECTION...SO CONFIDENCE IS GROWING THAT IT WILL HOLD TOGETHER
AND ARRIVE AT KSPI BETWEEN 19Z AND 21Z. ITS EVOLUTION BEYOND THAT
STILL REMAINS IN QUESTION...SO WILL ONLY CARRY VCTS AFTER 21Z AT
THE REMAINING TERMINALS. OUTSIDE OF ANY CONVECTION THAT DEVELOPS
THIS AFTERNOON...STRONG SOUTHERLY WINDS WILL GUST TO BETWEEN 25
AND 30KT. MODELS DISAGREE ABOUT THE TIMING/PLACEMENT OF ADDITIONAL
CONVECTION LATER TODAY AND TONIGHT...HOWEVER THE HRRR CONTINUES TO
FOCUS THE MOST WIDESPREAD STORMS DURING THE EVENING INTO THE
OVERNIGHT HOURS. WILL THEREFORE KEEP TEMPO GROUPS FOR THUNDER
BETWEEN 02Z AND 06Z AT KPIA AND BETWEEN 04Z AND 08Z FURTHER EAST
AT KCMI. AFTER THAT...MID-LEVEL DRYING IN THE WAKE OF THE
OVERNIGHT CONVECTION WILL LEAD TO A DRY TUESDAY MORNING.
BARNES
&&
.PREV DISCUSSION...
ISSUED 330 AM CDT MON MAY 20 2013
SHORT TERM...TODAY THROUGH THURSDAY
UNSETTLED WEATHER PATTERN EXPECTED THROUGH MID WEEK AS LARGE UPPER
LEVEL LOW OVER NE/SD GRADUALLY WEAKENS AS IT MOVES EASTWARD INTO
THE GREAT LAKES. SPC CONTINUES A SLIGHT RISK OF SEVERE STORMS
ACROSS MUCH OF IL FROM THIS AFTERNOON INTO TUE NIGHT. MODELS HAVE
TRENDED A BIT FASTER WITH WX SYSTEM AND SPC RISK OF SEVERE STORMS
ON WED IS EAST OF IL.
LEADING EDGE OF SHOWERS AND A FEW THUNDERSTORMS AS FAR EAST AS
PEORIA AND JACKSONVILLE WHILE STRONG TO SEVERE STORMS HEADING
TOWARD ST LOUIS METRO AREA EARLY THIS MORNING. MORE NUMEROUS
THUNDERSTORMS WERE OVER CENTRAL AND SW MO INTO SE KS WITH MCS
COMPLEX. ANOTHER AREA OF CONVECTION WAS OVER NE WI WITH ANOTHER
WEAKENING MCS. SURFACE MAP SHOWS DEEPENING 998 MB LOW PRESSURE
OVER CENTRAL SD WITH ITS WARM FRONT OVER NORTHERN WI WHILE ITS
COLD FRONT WAS OVER EASTERN NEBRASKA INTO CENTRAL KS/OK. IL WAS IN
WARM SECTOR WITH MOIST DEWPOINTS IN THE 60S AND EVEN 70F AT OLNEY
AND FAIRFIELD IN SE IL. TEMPS AT 3 AM WERE IN THE LOWER TO MIDDLE
70S EXCEPT RAIN COOLED MID 60S OVER WEST CENTRAL IL.
559 DM 500 MB LOW TO SLOWLY MOVE EAST INTO EASTERN SD BY SUNSET
WITH 998 MB SURFACE LOW MOVING INTO WEST CENTRAL MN. ANOTHER ROUND
OF SEVERE STORMS EXPECTED TO FIRE UP DURING MID/LATE AFTERNOON AND
CONTINUE INTO TONIGHT OVER THE CENTRAL PLAINS AND BE FURTHER EAST
INTO IL LATE THIS AFTERNOON AND TONIGHT. VERY UNSTABLE AIR MASS
WITH CAPES OF 2500-3500 J/KG AND GOOD WIND SHEAR TO AID IN THE
DEVELOPMENT OF SEVERE STORMS INCLUDING SOME SUPERCELLS. SPC HAS
15% RISK OF LARGE HAIL AND DAMAGING WIND GUSTS OVER IL WITH 30%
RISK OF LARGE HAIL FROM I-55 WEST AND 30% RISK OF DAMAGING WINDS
GUSTS FROM I-57 WEST. ALSO HAVE AT LEAST A 5% RISK OF TORNADOS
OVER MUCH OF IL EXCEPT FAR SE IL. HIGHS THIS AFTERNOON AGAIN IN
THE UPPER 80S TO NEAR 90F WITH DEWPOINTS IN THE UPPER 60S AND
LOWER 70S SO WILL FEEL LIKE A MID SUMMER DAY IN JULY.
UPPER LEVEL LOW STAYS IN PLACE NEAR SE SD TUE AND THEN WEAKENS A
BIT TO 562 DM AS IT TRACKS EASTWARD INTO EASTERN IA BY SUNSET WED
WHILE SURFACE LOW MOVES INTO SOUTHERN LAKE MI. ANOTHER SLIGHT RISK
OF SEVERE STORMS OVER MUCH OF IL TUE AFTERNOON/EVENING THOUGH NOT
QUITE AS UNSTABLE AS THIS AFTERNOON...AND SYSTEM IS STARTING TO
WEAKEN SO COVERAGE OF SEVERE STORMS APPEARS LESS. SPC HAS AT LEAST
15% RISK OF DAMAGING WINDS AND LARGE HAIL WITH THE 30% RISK SW IL SW
OF CLAY COUNTY. HIGHS TUE IN THE LOW TO MID 80S. SHOWERS STILL
LIKELY WED WITH A FEW THUNDERSTORMS ESPECIALLY OVER EASTERN IL.
RAINFALL AMOUNTS OF 1 TO 2 INCHES POSSIBLE TODAY THROUGH WED.
WEAKENING UPPER LEVEL TROF MOVES INTO IL THU KEEPING A CHANCE OF
SHOWERS AND ISOLATED THUNDERSTORMS ALONG WITH COOLER TEMPS WITH
HIGHS AROUND 70F FROM I-74 NORTH AND MID 70S IN SE IL.
LONG TERM...THURSDAY NIGHT THROUGH SUNDAY NIGHT
DRY WEATHER FINALLY RETURNS TO CENTRAL/SE IL THU NIGHT THROUGH FRI
NIGHT AS HIGHS PRESSURE SETTLES INTO THE GREAT LAKES REGIONS.
CARRIED 20-40% CHANCE OF SHOWERS AND THUNDERSTORMS FROM SAT
AFTERNOON THROUGH SUNDAY NIGHT OVER CENTRAL AND SE IL WITH SOME
MODELS SHOWING SHORT WAVE RIDGING OVER TOP OF UPPER LEVEL RIDGE INTO
PARTS OF IL THIS WEEKEND. THOUGH CONFIDENCE OF THIS HAPPENING IS LOW.
TEMPS SHOULD MODIFY EARLY NEXT WEEK WITH SOME UPPER LEVEL RIDGING
INTO IL.
07
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
534 PM EDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 532 PM EDT MON MAY 20 2013
SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE TO INCREASE TONIGHT THROUGH
WEDNESDAY...WITH A FEW SHOWERS POSSIBLY LINGERING INTO THURSDAY.
THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS EVENING
THROUGH TUESDAY NIGHT. DRIER AND COOLER WEATHER IS ANTICIPATED
LATE THIS WEEK INTO NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
REMNANT GRAVITY WAVE FROM OVERNIGHT CONVECTION AND
ASSOCIATED WITH A ~10F DEGREE DEWPOINT DROP IN ITS WAKE HAS WASHED
OUT AS IT MOVED INTO OUR FORECAST AREA. THIS HAS KEPT MODERATELY
UNSTABLE AIRMASS ACROSS THE EASTERN TWO-THIRDS OF OUR FORECAST AREA.
ADDED SLIGHT CHANCE POPS FOR THE EAST THIS EVENING AS CONVECTION
COULD FIRE ALONG OR IN FRONT OF THIS BOUNDARY WHERE THE AIRMASS IS
CHARACTERIZED BY SBCAPE VALUES IN EXCESS OF 3000 J/KG. THE GREATEST
LIMITING FACTOR IS THE LACK OF SIGNIFICANT FORCING...ALTHOUGH
CONVECTION ACROSS MICHIGAN AND ADDITIONAL CONVECTION FIRING ALONG
THE BOUNDARY ACROSS EASTERN ILLINOIS AT 1830Z INDICATES THIS
BOUNDARY MAY PROVIDE JUST ENOUGH FORCED ASCENT FOR ISOLATED STORM
DEVELOPMENT.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE EVOLUTION AND IMPACTS
ACROSS OUR AREA TONIGHT. DECAYING STORM CLUSTER ACROSS WESTERN
ILLINOIS SHOULD CONTINUE ITS WEAKENING TREND AS IT MOVES INTO A
MOISTURE VOID AREA ACROSS ILLINOIS WITH SURFACE DEWPOINTS IN THE
UPPER 50S. WITH THAT BEING SAID...SOME SHORT TERM MODEL GUIDANCE IS
INDICATING A QUICK RECOVERY OF THE MOISTURE PROFILE IN THAT AREA AS
850 MOISTURE TRANSPORT INCREASES THIS AFTERNOON. IF THE AIRMASS
AHEAD OF THESE STORMS CAN DESTABILIZE OVER THE NEXT FEW HOURS...AS
THE HRRR SUGGESTS...UPSCALE GROWTH OF THAT CLUSTER AS WELL AS
ADDITIONAL STORM DEVELOPMENT MAY TRACK ACROSS THE NORTHWEST PORTION
OF OUR FORECAST AREA DURING THE LATE EVENING. IF STORMS CAN
DEVELOP...SEVERE POTENTIAL DOES EXIST AS 0-6 KM SHEAR OF 35-45 KNOTS
OVERSPREADS THE NORTHWEST PORTION OF OUR FORECAST AREA WITH THE MAIN
THREATS BEING SEVERE HAIL AND WIND.
REMAIN MORE CONFIDENT IN PRECIPITATION CHANCES AFTER 06Z WHEN
REMNANT CONVECTION FROM MISSOURI TRACKS TOWARDS THE AREA. SEVERE
THREAT WILL BE MINIMAL WITH THIS CONVECTION DUE TO ITS TIMING DURING
THE EARLY MORNING HOURS.
TUESDAY LOOKS TO BE COOLER THAN TODAY AS LITTLE SUN WILL BE SEEN
ACROSS OUR FORECAST AREA DUE TO CLOUD DEBRIS FROM FROM OVERNIGHT
CONVECTION AS WELL AS ADDITIONAL DYNAMIC LIFT FROM 40-50 KT LLJ.
SEVERE THREAT DOES EXIST IF A FEW BREAKS IN THE CLOUDS CAN PROVIDE
SIGNIFICANT SURFACE HEATING FOR EVEN MARGINAL SURFACE BASED
INSTABILITY. THE MAIN THREAT WILL BE LARGE HAIL AND DAMAGING WINDS
AS UNIDIRECTIONAL 35-40 KNOT SHEAR OVERSPREADS THE AREA.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
ONE OR TWO MORE ROUNDS OF CONVECTION TO BEGIN THE FORECAST PERIOD.
MODELS IN PRETTY GOOD AGREEMENT IN SHORT WAVE COMING OUT OF BASE OF
CLOSED LOW AND IMPACTING THE AREA TUE NIGHT. GOOD SUPPORT WILL
ACCOMPANY THIS FEATURE AND 50-60KT MID LEVEL SPEED MAX WILL COMBINE
WITH INFLUX OF LOW LEVEL MOISTURE WITH AT LEAST SUFFICIENT
INSTABILITY TO INITIATE OR MAINTAIN CONVECTION. UNIDIRECTIONAL WIND
PROFILE WITH AROUND 30KT OF SPEED SHEAR WILL HAVE DAMAGING WINDS AS
THE MAIN SEVERE THREAT. CLOSED LOW FINALLY OPENS UP AND WILL MOVE
EASTWARD INTO THE GREAT LAKES REGION WEDNESDAY NIGHT...BRINGING SFC
LOW AND MAIN COLD FRONT WITH IT. MODELS OFFERING VARYING
TIMING/PLACEMENT OF THESE FEATURES BUT ONE MORE ROUND OF CONVECTION
POSSIBLE WEDNESDAY...MAINLY FOR THE EASTERN HALF OF THE CWA. UPPER
TROF AXIS ROTATES THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY
KEEPING CHANCE FOR A FEW SHOWERS BEFORE COOLER DRIER CANADIAN HIGH
PRESSURE BEGINS TO BUILD INTO THE GREAT LAKES REGION ON FRIDAY. THIS
WILL PROVIDE A NICE START TO THE HOLIDAY WEEKEND...QUESTIONS REMAIN
AS TO WHETHER IT WILL LAST THROUGH MONDAY. SFC RIDGE AXIS WILL
PROGRESS EASTWARD SUNDAY AND MONDAY...PLACING OUR AREA ON THE
WESTERN PERIPHERY OF THE HIGH WHILE MEDIUM RANGE MODELS ATTEMPTING
TO BRING SHORT WAVE ENERGY DOWN IN NW FLOW. GETTING BETTER MODEL
AGREEMENT WITH THIS SOLN BUT LOTS OF VARIATION IN TIMING AND
PLACEMENT. ENSEMBLE GUIDANCE NEAR OR MOSTLY BELOW CLIMO FOR POPS AS
WELL SO WILL STILL HOLD OUT FOR DRY FORECAST FOR AT LEAST ONE MORE
ISSUANCE. TEMPS TRENDING SEASONABLY COOLER WITH AOB NORMAL FOR MOST
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 128 PM EDT MON MAY 20 2013
VFR CONDITIONS EXPECTED FOR THE REST OF TODAY AND INTO
THE OVERNIGHT HOURS. SLIGHT CHANCE THAT A STRAY SHOWER OR ISOLATED
STORM COULD POP UP NEAR KFWA...BUT CONFIDENCE WAS TOO LOW FOR
INCLUSION IN 18Z TAF ISSUANCE. STORMS WILL FIRE ACROSS MISSOURI
TODAY AND WILL LIKELY TRACK INTO NORTHERN INDIANA DURING THE EARLY
MORNING HOURS. THIS THREAT IS GREATEST AT KSBN. WILL WAIT FOR LATER
TAF ISSUANCES BEFORE INCLUDING THESE STORMS AS SUBTLE TIMING
DIFFERENCES AND EXACT LOCATION WILL NOT BE KNOWN UNTIL THE
CONVECTION HAS FIRED AND BEGINS TRACKING TOWARDS THE AREA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL/KG
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION...BENTLEY
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
307 PM EDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 1052 AM EDT MON MAY 20 2013
A SLOW MOVING LOW PRESSURE SYSTEM WILL BRING INCREASING CHANCES
FOR SHOWERS AND THUNDERSTORMS LATER TODAY THROUGH WEDNESDAY...WITH
A FEW SHOWERS POSSIBLY LINGERING INTO THURSDAY. THERE IS A SLIGHT
RISK FOR SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH TUESDAY
NIGHT. DRIER AND COOLER WEATHER IS ANTICIPATED LATE THIS WEEK
INTO NEXT WEEKEND.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
REMNANT GRAVITY WAVE FROM OVERNIGHT CONVECTION AND
ASSOCIATED WITH A ~10F DEGREE DEWPOINT DROP IN ITS WAKE HAS WASHED
OUT AS IT MOVED INTO OUR FORECAST AREA. THIS HAS KEPT MODERATELY
UNSTABLE AIRMASS ACROSS THE EASTERN TWO-THIRDS OF OUR FORECAST AREA.
ADDED SLIGHT CHANCE POPS FOR THE EAST THIS EVENING AS CONVECTION
COULD FIRE ALONG OR IN FRONT OF THIS BOUNDARY WHERE THE AIRMASS IS
CHARACTERIZED BY SBCAPE VALUES IN EXCESS OF 3000 J/KG. THE GREATEST
LIMITING FACTOR IS THE LACK OF SIGNIFICANT FORCING...ALTHOUGH
CONVECTION ACROSS MICHIGAN AND ADDITIONAL CONVECTION FIRING ALONG
THE BOUNDARY ACROSS EASTERN ILLINOIS AT 1830Z INDICATES THIS
BOUNDARY MAY PROVIDE JUST ENOUGH FORCED ASCENT FOR ISOLATED STORM
DEVELOPMENT.
STILL SOME UNCERTAINTY REGARDING CONVECTIVE EVOLUTION AND IMPACTS
ACROSS OUR AREA TONIGHT. DECAYING STORM CLUSTER ACROSS WESTERN
ILLINOIS SHOULD CONTINUE ITS WEAKENING TREND AS IT MOVES INTO A
MOISTURE VOID AREA ACROSS ILLINOIS WITH SURFACE DEWPOINTS IN THE
UPPER 50S. WITH THAT BEING SAID...SOME SHORT TERM MODEL GUIDANCE IS
INDICATING A QUICK RECOVERY OF THE MOISTURE PROFILE IN THAT AREA AS
850 MOISTURE TRANSPORT INCREASES THIS AFTERNOON. IF THE AIRMASS
AHEAD OF THESE STORMS CAN DESTABILIZE OVER THE NEXT FEW HOURS...AS
THE HRRR SUGGESTS...UPSCALE GROWTH OF THAT CLUSTER AS WELL AS
ADDITIONAL STORM DEVELOPMENT MAY TRACK ACROSS THE NORTHWEST PORTION
OF OUR FORECAST AREA DURING THE LATE EVENING. IF STORMS CAN
DEVELOP...SEVERE POTENTIAL DOES EXIST AS 0-6 KM SHEAR OF 35-45 KNOTS
OVERSPREADS THE NORTHWEST PORTION OF OUR FORECAST AREA WITH THE MAIN
THREATS BEING SEVERE HAIL AND WIND.
REMAIN MORE CONFIDENT IN PRECIPITATION CHANCES AFTER 06Z WHEN
REMNANT CONVECTION FROM MISSOURI TRACKS TOWARDS THE AREA. SEVERE
THREAT WILL BE MINIMAL WITH THIS CONVECTION DUE TO ITS TIMING DURING
THE EARLY MORNING HOURS.
TUESDAY LOOKS TO BE COOLER THAN TODAY AS LITTLE SUN WILL BE SEEN
ACROSS OUR FORECAST AREA DUE TO CLOUD DEBRIS FROM FROM OVERNIGHT
CONVECTION AS WELL AS ADDITIONAL DYNAMIC LIFT FROM 40-50 KT LLJ.
SEVERE THREAT DOES EXIST IF A FEW BREAKS IN THE CLOUDS CAN PROVIDE
SIGNIFICANT SURFACE HEATING FOR EVEN MARGINAL SURFACE BASED
INSTABILITY. THE MAIN THREAT WILL BE LARGE HAIL AND DAMAGING WINDS
AS UNIDIRECTIONAL 35-40 KNOT SHEAR OVERSPREADS THE AREA.
&&
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 305 PM EDT MON MAY 20 2013
ONE OR TWO MORE ROUNDS OF CONVECTION TO BEGIN THE FORECAST PERIOD.
MODELS IN PRETTY GOOD AGREEMENT IN SHORT WAVE COMING OUT OF BASE OF
CLOSED LOW AND IMPACTING THE AREA TUE NIGHT. GOOD SUPPORT WILL
ACCOMPANY THIS FEATURE AND 50-60KT MID LEVEL SPEED MAX WILL COMBINE
WITH INFLUX OF LOW LEVEL MOISTURE WITH AT LEAST SUFFICIENT
INSTABILITY TO INITIATE OR MAINTAIN CONVECTION. UNIDIRECTIONAL WIND
PROFILE WITH AROUND 30KT OF SPEED SHEAR WILL HAVE DAMAGING WINDS AS
THE MAIN SEVERE THREAT. CLOSED LOW FINALLY OPENS UP AND WILL MOVE
EASTWARD INTO THE GREAT LAKES REGION WEDNESDAY NIGHT...BRINGING SFC
LOW AND MAIN COLD FRONT WITH IT. MODELS OFFERING VARYING
TIMING/PLACEMENT OF THESE FEATURES BUT ONE MORE ROUND OF CONVECTION
POSSIBLE WEDNESDAY...MAINLY FOR THE EASTERN HALF OF THE CWA. UPPER
TROF AXIS ROTATES THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY
KEEPING CHANCE FOR A FEW SHOWERS BEFORE COOLER DRIER CANADIAN HIGH
PRESSURE BEGINS TO BUILD INTO THE GREAT LAKES REGION ON FRIDAY. THIS
WILL PROVIDE A NICE START TO THE HOLIDAY WEEKEND...QUESTIONS REMAIN
AS TO WHETHER IT WILL LAST THROUGH MONDAY. SFC RIDGE AXIS WILL
PROGRESS EASTWARD SUNDAY AND MONDAY...PLACING OUR AREA ON THE
WESTERN PERIPHERY OF THE HIGH WHILE MEDIUM RANGE MODELS ATTEMPTING
TO BRING SHORT WAVE ENERGY DOWN IN NW FLOW. GETTING BETTER MODEL
AGREEMENT WITH THIS SOLN BUT LOTS OF VARIATION IN TIMING AND
PLACEMENT. ENSEMBLE GUIDANCE NEAR OR MOSTLY BELOW CLIMO FOR POPS AS
WELL SO WILL STILL HOLD OUT FOR DRY FORECAST FOR AT LEAST ONE MORE
ISSUANCE. TEMPS TRENDING SEASONABLY COOLER WITH AOB NORMAL FOR MOST
OF THE FCST PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 128 PM EDT MON MAY 20 2013
VFR CONDITIONS EXPECTED FOR THE REST OF TODAY AND INTO
THE OVERNIGHT HOURS. SLIGHT CHANCE THAT A STRAY SHOWER OR ISOLATED
STORM COULD POP UP NEAR KFWA...BUT CONFIDENCE WAS TOO LOW FOR
INCLUSION IN 18Z TAF ISSUANCE. STORMS WILL FIRE ACROSS MISSOURI
TODAY AND WILL LIKELY TRACK INTO NORTHERN INDIANA DURING THE EARLY
MORNING HOURS. THIS THREAT IS GREATEST AT KSBN. WILL WAIT FOR LATER
TAF ISSUANCES BEFORE INCLUDING THESE STORMS AS SUBTLE TIMING
DIFFERENCES AND EXACT LOCATION WILL NOT BE KNOWN UNTIL THE
CONVECTION HAS FIRED AND BEGINS TRACKING TOWARDS THE AREA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SYNOPSIS...STEINWEDEL
SHORT TERM...BENTLEY
LONG TERM...JAL
AVIATION...BENTLEY
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.NORTHERNIN.GOV
WWW.TWITTER.COM/NWSIWX
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS TOPEKA KS
353 PM CDT MON MAY 20 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 350 PM CDT MON MAY 20 2013
LATEST MESO ANALYSIS AT 19Z SHOWS A COUPLE OF FRONTS IN AND NEAR OUR
CWA. FIRST IS OFF TO THE WEST ACROSS CENTRAL KANSAS WITH THE OTHER
EXTENDING FROM NORTH CENTRAL OKLAHOMA INTO FAR SOUTHERN EAST CENTRAL
KANSAS SOUTH OF I-35. MOISTURE CONVERGENCE WAS NOTED ALONG BOTH OF
THE BOUNDARIES WITH THE STRONGEST ALONG THE SOUTHERN COUNTIES. BULK
SHEAR VALUES ARE STRONG ACROSS MUCH OF THE AREA WITH HIGHEST
INSTABILITY ACROSS SOUTHEAST KANSAS INTO EAST CENTRAL KANSAS.
0-1 KM STORM RELATIVE HELICITY AROUND 100 TO 120 M2/S2 ACROSS
SOUTHEAST AND EAST CENTRAL KANSAS. WINDS ARE BACKED SLIGHTLY IN THE
LOW LEVELS ALONG AND SOUTH OF I-35. ISOLATED TORNADO THREAT WILL
CONTINUE ALONG AND SOUTHEAST OF I-35 THROUGH MID EVENING.
HRRR AND RAP DEVELOP SCATTERED CONVECTION ACROSS NORTH CENTRAL AND
NORTHEAST KANSAS LATE THIS AFTERNOON AND EVENING. ALSO WATER VAPOR
SHOWS A MID LEVEL WAVE MOVING ACROSS SOUTHWEST KANSAS THIS WILL BE
COUPLED WITH ENERGY ROTATING AROUND THE NORTHERN PLAINS UPPER LOW
ACROSS NEBRASKA AND NORTH CENTRAL NEBRASKA THIS EVENING. WILL
CONTINUE WITH EVENING CHANCES OF THUNDERSTORMS ACROSS NORTH CENTRAL
AND NORTHEAST KANSAS. HIGHEST CHANCES WILL BE ALONG AND SOUTH OF
I-35. PRECIPITATION SHOULD MOVE OFF TO THE SOUTHEAST LATER TONIGHT
AS THE COOL FRONT MOVES EASTWARD. LOWS TONIGHT WILL BE IN THE 50S.
TUESDAY SHOULD BE RELATIVELY DRY ACROSS MUCH OF THE FORECAST AREA
SAVE THE FAR SOUTHEAST COUNTIES OF EAST CENTRAL KANSAS. BEST FORCING
WILL BE FOCUSED FURTHER SOUTH TUESDAY FROM OKLAHOMA INTO SOUTHERN
MISSOURI. HIGHS WILL BE IN THE MID 70S TUESDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 350 PM CDT MON MAY 20 2013
LAST SHORTWAVE LOBE ON THE SOUTHERN PORTIONS OF THE UPPER LOW WILL
ROTATE SOUTHEAST OF THE COUNTY WARNING AREA TUESDAY NIGHT...SO
WILL CONTINUE WITH A DRY FCST TUESDAY NIGHT ON INTO THURSDAY AS
THE UPPER LOW SETTLES INTO THE EASTERN CONUS. BY THURSDAY NIGHT
INTO FRIDAY...INCREASING MOISTURE AND WARM AIR ADVECTION WILL TAKE
PLACE ON THE EASTERN SIDE OF BUILDING UPPER LEVEL RIDGE. WILL
INTRODUCE POPS AGAIN AT THAT TIME AND PERSIST THROUGH THE WEEKEND
AS WEAK SHORTWAVES MOVE THROUGH THE FLOW AND INTO THE RIDGE AXIS
NEAR THE COUNTY WARNING AREA. THIS WARRANTS KEEPING CONVECTIVE
POTENTIAL GOING THROUGH THE PERIOD...ALTHOUGH MODELS TRENDS ARE
HINTING THAT AN AMPLIFICATION OF THE UPPER RIDGE INTO EARLY NEXT
WEEK MAY FORCE THE STRONGER FLOW ALOFT AND HIGHER PRECIP CHANCES A
LITTLE FURTHER NORTH WITH IT. EITHER WAY...A GRADUAL WARMING TREND
STILL LOOKS ON TRACK AS WELL WITH HIGHS WARMING FROM MAINLY THE
70S WEDNESDAY INTO FRIDAY...THEN INTO THE LOW TO MIDDLE 80S FOR
THE WEEKEND INTO EARLY NEXT WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 350 PM CDT MON MAY 20 2013
VFR EXPECTED THROUGH THE PERIOD OUTSIDE OF CONVECTION LATE THIS
AFTERNOON AND EVENING. ADDED VCTS TO THE TERMINALS THIS AFTERNOON
FOR POSSIBLE CONVECTIVE DEVELOPMENT. EXPECT THE MAIN CONVECTION TO
REMAIN SOUTH OF THE TERMINALS. WINDS SOUTHWEST AROUND 10 KTS OR
LESS BECOMING MORE WESTERLY UNDER 10 KTS AFTER 04Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...53
LONG TERM...63
AVIATION...53
AREA FORECAST DISCUSSION
NWS JACKSON KY
106 PM EDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1223 PM EDT MON MAY 20 2013
WHILE A FEW MORE SHOWERS MAY CLIP THE EXTREME EASTERN END OF PIKE
COUNTY...THE MAIN BAND OF CONVECTION HAS FINALLY SHIFTED EAST. AM
STILL RELUCTANT TO REMOVE ALL CHANCES OF RAIN FOR THIS AFTERNOON AND
WILL LEAVE THE CURRENT LOW PROBABILITIES IN PLACE FOR THE EAST AND
CENTRAL AREAS. THE 14Z HRRR HAS TRENDED TOWARDS SOME ISOLATED
CONVECTION FOR THIS AFTERNOON. IT SHOULD ALSO BE NOTED THE HRRR WAS
MUCH TOO QUICK TO MOVE THE CONVECTIVE BAND OVER ERN KY AND WV EAST
THIS MORNING. HAVE UPDATED NDFD FOR LATEST TRENDS AND WILL UPDATE ZFP
SHORTLY.
UPDATE ISSUED AT 1036 AM EDT MON MAY 20 2013
PERSISTENT CONVECTION CONTINUES TO AFFECT FAR EASTERN PIKE COUNTY. IN
FACT CONVECTION CONTINUES TO DEVELOP UPSTREAM ALL THE WAY TO EAST OF
COLUMBUS OH. THE GOOD NEWS IS THAT THE BOUNDARY FOCUSING THIS
CONVECTION IS GRADUALLY SHIFTING EAST...AND WILL BE EAST OF PIKE
COUNTY BY EARLY AFTERNOON. THE RAINFALL RATES HAVE ALSO BEEN LESS THE
PAST COUPLE OF HOURS. FOR EXAMPLE THE PHELPS IFLOWS GAGE IS REPORTING
0.71 SINCE THE EVENT BEGAN...WITH 0.51 OF THIS FALLING BETWEEN 09Z
AND 10Z.
ONCE THE BAND OF CONVECTION IN THE FAR EAST MOVES OUT OF THE
STATE...THE 12Z HRRR AND 12Z NAM SHOW NO RAIN OVER OUR AREA FOR THE
REST OF THE DAY. HOWEVER HAVE ELECTED TO LEAVE THE LOW CHANCE
PROBABILITIES OF RAIN FOR THE EAST AND CENTRAL PART OF THE FORECAST
AREA. MORNING SOUNDINGS ARE QUITE UNSTABLE WITH LI OF -8 AT ILN AND -6
AT OHX. AM CONCERNED THAT BOUNDARIES LEFT FROM THIS MORNINGS
CONVECTION COULD FOCUS SOME ADDITIONAL CONVECTION LATER THIS
AFTERNOON.
HAVE UPDATED NDFD FOR LATEST HOURLY TRENDS BUT ZFP DOES NOT NEED AN
UPDATE AT THIS TIME.
UPDATE ISSUED AT 727 AM EDT MON MAY 20 2013
CONVECTION HAS BEEN PERSISTENT ACROSS FAR SOUTHEASTERN KENTUCKY EARLY
THIS MORNING. THE LATEST NAM AND SREF CONTINUE TO SHOW SOME ACTIVITY
LINGERING INTO THE MID-MORNING HOURS. AS SUCH...WILL ALLOW FOR HIGHER
POPS IN THE FAR EAST. THE FOG HAS ALSO BEEN MORE SPOTTY THIS
MORNING...SO WILL DOWNPLAY THIS INTO THE MID-MORNING HOURS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 351 AM EDT MON MAY 20 2013
A LEFTOVER OUTFLOW BOUNDARY MOVING THROUGH SOUTHEASTERN KENTUCKY HAS
SPARKED A BROKEN LINE OF SHOWERS AND THUNDERSTORMS...WITH EVEN A
STRAY SHOWER CURRENTLY AFFECTING THE JKL OFFICE. WILL INCLUDE SOME
ISOLATED POPS EARLY THIS MORNING GIVEN THESE TRENDS...ALTHOUGH THE
MAIN LINE LOOKS TO EXIT THE SOUTHEAST BETWEEN 4 AND 4:30 AM.
OTHERWISE...UPPER LEVEL RIDGING WILL BE BUILDING IN THROUGH THE DAY
TODAY ACROSS THE COMMONWEALTH IN RESPONSE TO A DEEP TROUGH SLOWLY
NUDGING EAST ACROSS THE PLAINS. THIS WILL RESULT IN MORE ISOLATED
CONVECTIVE COVERAGE. DESPITE A LACK OF DEEPER MOISTURE...THE LATEST
FORECAST SOUNDINGS SHOW QUITE A BIT OF INSTABILITY...SO ANYTHING THAT
DOES INITIATE COULD BE STRONG. WILL HIGHLIGHT THIS IN THE HWO. HIGHS
WILL TOP OUT IN THE MID 80S FOR MOST.
SKIES WILL CLEAR OUT TONIGHT...ALLOWING FOR SOME FOG ONCE AGAIN. LOWS
WILL BOTTOM OUT IN THE LOW TO MID 60S. ON TUESDAY...THE PLAINS TROUGH
WILL BE GETTING A LITTLE CLOSER AND ANY CAPPING WILL BE WEAK. WILL
ALLOW FOR SCATTERED CONVECTION DURING THE AFTERNOON HOURS...WITH SOME
OF THIS POSSIBLY BECOMING STRONG ONCE AGAIN...ESPECIALLY NEAR THE
BLUEGRASS COUNTIES. HIGHS WILL SOAR INTO THE UPPER 80S...THREATENING
RECORD HIGHS FOR THE DATE AT JKL AND LOZ.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 425 AM EDT MON MAY 20 2013
THE PERIOD SHOULD BEGIN RATHER ACTIVE AS AN UPPER LEVEL LOW INITIALLY
OVER THE PLAINS/MO VALLEY REGION AND A SHORTWAVE TROUGH EXTENDING TO
ITS SOUTH APPROACHES THE MS VALLEY AND LOWER OH VALLEY REGION TUE
NIGHT INTO EARLY ON WED. THE ASSOCIATED SFC LOW SHOULD DEEPEN A BIT
AS IT TRACKS TOWARD THE WESTERN GREAT LAKES REGION TUE NIGHT INTO
WED. A LOW LEVEL JET SHOULD TRANSPORT RATHER ABUNDANT MOISTURE INTO
THE REGION WITH PW FORECAST TO INCREASE TO AROUND 1.4 TO 1.5 INCHES.
THE UPPER LEVEL LOW WILL GRADUALLY OPEN UP WITH A SHORTWAVE TROUGH
WORKING ACROSS EASTERN KY LATER ON WED INTO WED NIGHT. MODELS BRING
SOME INCREASING WINDS ALOFT INTO THE AREA AT THAT POINT...THOUGH THE
STRONGER SHEAR SHOULD REMAIN TO OUR NORTH. THE UPPER LEVEL LOW SHOULD
WORK SLOWLY EAST SOUTHEAST REACHING THE UPPER OH VALLEY REGION AND
MID ATLANTIC STATES THU NIGHT INTO FRIDAY. AT THE SFC...THE LOW WILL
TRACK INTO THE EASTERN GREAT LAKES WED NIGHT AND THEN NORTHEAST
ACROSS THE ST LAWRENCE VALLEY WITH THE TRAILING COLD FRONT CROSSING
EASTERN KY ON THU.
THERE WILL PROBABLY BE A LULL IN CONVECTION FOR A TIME ON TUE NIGHT
BETWEEN RATHER DIURNALLY DRIVEN CONFECTION FROM TUE AND RESURGENCE
LIKELY TO OUR WEST AND SOUTHWEST WITH STRENGTHENING LOW LEVEL JET AND
APPROACHING UPPER LEVEL SHORTWAVE LATE TUE NIGHT. MODEL FORECAST
INSTABILITY AND SHEAR ALONG WITH TIMING OF MODELS BRINGING PREFRONTAL
CONVECTION INTO EASTERN KY POINT TOWARD THE POSSIBILITY OF STRONG TO
LOCALLY SEVERE STORMS POSSIBLE ANYWHERE IN THE CWA THOUGH THE NORTH
WILL BE CLOSER TO THE STRONGER LOW LEVEL JET CORE AS HIGHLIGHTED BY
SPC DAY 3 OUTLOOK. THE POTENTIAL FOR LOCALLY HEAVY RAIN AND SOME OF
THE STORMS TO BECOME STRONG WILL BE HIGHLIGHTED FOR WED IN THE HWO.
LIKELY POPS WERE USED FOR WED IN LINE WITH THE MODEL CONSENSUS AND
MOS GUIDANCE. THE MAV NUMBERS CONTINUE TO APPEAR TOO WARM UNLESS
THERE ENDS UP BEING LITTLE CLOUD COVER ON WED AND HIGH TEMPS WERE
TRENDED LOWER TOWARD MODEL CONSENSUS/MET GUIDANCE.
POPS WERE CONTINUED BEHIND THE BOUNDARY INTO FRI AS THE UPPER LEVEL
SYSTEM GRADUALLY WORKS ACROSS THE REGION. THE EXTENDED MODELS
APPEAR TO BE A IN A BIT BETTER AGREEMENT WITH THE UPPER LEVEL
LOW/SHORTWAVE TROUGH TO MOVE ACROSS THE AREA THU INTO FRI.
HOWEVER...LATER IN THE PERIOD THE GFS MAY BE SUFFERING FROM SOME
CONVECTIVE FEEDBACK ISSUES ACROSS THE PLAINS TO WESTERN GREAT LAKES
REGION SAT INTO SUN WHILE THE ECMWF CONTINUES TO DEVELOP CONVECTION
WITH DISTURBANCES IN NW FLOW INTERACTING WITH A WARM FRONT ADVANCING
TOWARD THE LOWER OH VALLEY REGION LATE IN THE PERIOD. THE EXTENDED
GRID LOAD MODEL CONSENSUS HAD SLIGHT CHANCE TO CHANCE POPS FOR SUN
AND THIS WAS GENERALLY FOLLOWED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 106 PM EDT MON MAY 20 2013
EXTENSIVE FIELD OF CU AND SC IS ACROSS THE AREA. SKY CONDITIONS ARE
QUITE VARIABLE RANGING FROM SCT TO OVC...WITH CEILINGS RANGING FROM
LESS THAN 3K FEET TO AROUND 5K FEET. CEILINGS WILL BE LIFTING
THROUGH THE REMAINDER OF THE AFTERNOON...WITH CLOUDS ALSO SCATTERING
OUT LATE. AS SUCH VFR CONDITIONS WILL PREVAIL INTO THE NIGHT. WITH UPPER
LEVEL HIGH PRESSURE BUILDING INTO THE AREA THUNDERSTORMS WILL BE MUCH
LESS LIKELY FOR THE REMAINDER OF THE DAY...ALTHOUGH AN ISOLATED
SHOWER OR THUNDERSTORM CANNOT BE RULED OUT IN THE CENTRAL AND EASTERN
PART OF THE FORECAST AREA. MVFR FOG CAN BE EXPECTED TOWARDS DAWN ON
TUESDAY...BUT THIS WILL BE VERY SHORT LIVED.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...GEOGERIAN
LONG TERM...JP
AVIATION...SBH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1223 PM EDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1223 PM EDT MON MAY 20 2013
WHILE A FEW MORE SHOWERS MAY CLIP THE EXTREME EASTERN END OF PIKE
COUNTY...THE MAIN BAND OF CONVECTION HAS FINALLY SHIFTED EAST. AM
STILL RELUCTANT TO REMOVE ALL CHANCES OF RAIN FOR THIS AFTERNOON AND
WILL LEAVE THE CURRENT LOW PROBABILITIES IN PLACE FOR THE EAST AND
CENTRAL AREAS. THE 14Z HRRR HAS TRENDED TOWARDS SOME ISOLATED
CONVECTION FOR THIS AFTERNOON. IT SHOULD ALSO BE NOTED THE HRRR WAS
MUCH TOO QUICK TO MOVE THE CONVECTIVE BAND OVER ERN KY AND WV EAST
THIS MORNING. HAVE UPDATED NDFD FOR LATEST TRENDS AND WILL UPDATE ZFP
SHORTLY.
UPDATE ISSUED AT 1036 AM EDT MON MAY 20 2013
PERSISTENT CONVECTION CONTINUES TO AFFECT FAR EASTERN PIKE COUNTY. IN
FACT CONVECTION CONTINUES TO DEVELOP UPSTREAM ALL THE WAY TO EAST OF
COLUMBUS OH. THE GOOD NEWS IS THAT THE BOUNDARY FOCUSING THIS
CONVECTION IS GRADUALLY SHIFTING EAST...AND WILL BE EAST OF PIKE
COUNTY BY EARLY AFTERNOON. THE RAINFALL RATES HAVE ALSO BEEN LESS THE
PAST COUPLE OF HOURS. FOR EXAMPLE THE PHELPS IFLOWS GAGE IS REPORTING
0.71 SINCE THE EVENT BEGAN...WITH 0.51 OF THIS FALLING BETWEEN 09Z
AND 10Z.
ONCE THE BAND OF CONVECTION IN THE FAR EAST MOVES OUT OF THE
STATE...THE 12Z HRRR AND 12Z NAM SHOW NO RAIN OVER OUR AREA FOR THE
REST OF THE DAY. HOWEVER HAVE ELECTED TO LEAVE THE LOW CHANCE
PROBABILITIES OF RAIN FOR THE EAST AND CENTRAL PART OF THE FORECAST
AREA. MORNING SOUNDINGS ARE QUITE UNSTABLE WITH LI OF -8 AT ILN AND -6
AT OHX. AM CONCERNED THAT BOUNDARIES LEFT FROM THIS MORNINGS
CONVECTION COULD FOCUS SOME ADDITIONAL CONVECTION LATER THIS
AFTERNOON.
HAVE UPDATED NDFD FOR LATEST HOURLY TRENDS BUT ZFP DOES NOT NEED AN
UPDATE AT THIS TIME.
UPDATE ISSUED AT 727 AM EDT MON MAY 20 2013
CONVECTION HAS BEEN PERSISTENT ACROSS FAR SOUTHEASTERN KENTUCKY EARLY
THIS MORNING. THE LATEST NAM AND SREF CONTINUE TO SHOW SOME ACTIVITY
LINGERING INTO THE MID-MORNING HOURS. AS SUCH...WILL ALLOW FOR HIGHER
POPS IN THE FAR EAST. THE FOG HAS ALSO BEEN MORE SPOTTY THIS
MORNING...SO WILL DOWNPLAY THIS INTO THE MID-MORNING HOURS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 351 AM EDT MON MAY 20 2013
A LEFTOVER OUTFLOW BOUNDARY MOVING THROUGH SOUTHEASTERN KENTUCKY HAS
SPARKED A BROKEN LINE OF SHOWERS AND THUNDERSTORMS...WITH EVEN A
STRAY SHOWER CURRENTLY AFFECTING THE JKL OFFICE. WILL INCLUDE SOME
ISOLATED POPS EARLY THIS MORNING GIVEN THESE TRENDS...ALTHOUGH THE
MAIN LINE LOOKS TO EXIT THE SOUTHEAST BETWEEN 4 AND 4:30 AM.
OTHERWISE...UPPER LEVEL RIDGING WILL BE BUILDING IN THROUGH THE DAY
TODAY ACROSS THE COMMONWEALTH IN RESPONSE TO A DEEP TROUGH SLOWLY
NUDGING EAST ACROSS THE PLAINS. THIS WILL RESULT IN MORE ISOLATED
CONVECTIVE COVERAGE. DESPITE A LACK OF DEEPER MOISTURE...THE LATEST
FORECAST SOUNDINGS SHOW QUITE A BIT OF INSTABILITY...SO ANYTHING THAT
DOES INITIATE COULD BE STRONG. WILL HIGHLIGHT THIS IN THE HWO. HIGHS
WILL TOP OUT IN THE MID 80S FOR MOST.
SKIES WILL CLEAR OUT TONIGHT...ALLOWING FOR SOME FOG ONCE AGAIN. LOWS
WILL BOTTOM OUT IN THE LOW TO MID 60S. ON TUESDAY...THE PLAINS TROUGH
WILL BE GETTING A LITTLE CLOSER AND ANY CAPPING WILL BE WEAK. WILL
ALLOW FOR SCATTERED CONVECTION DURING THE AFTERNOON HOURS...WITH SOME
OF THIS POSSIBLY BECOMING STRONG ONCE AGAIN...ESPECIALLY NEAR THE
BLUEGRASS COUNTIES. HIGHS WILL SOAR INTO THE UPPER 80S...THREATENING
RECORD HIGHS FOR THE DATE AT JKL AND LOZ.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 425 AM EDT MON MAY 20 2013
THE PERIOD SHOULD BEGIN RATHER ACTIVE AS AN UPPER LEVEL LOW INITIALLY
OVER THE PLAINS/MO VALLEY REGION AND A SHORTWAVE TROUGH EXTENDING TO
ITS SOUTH APPROACHES THE MS VALLEY AND LOWER OH VALLEY REGION TUE
NIGHT INTO EARLY ON WED. THE ASSOCIATED SFC LOW SHOULD DEEPEN A BIT
AS IT TRACKS TOWARD THE WESTERN GREAT LAKES REGION TUE NIGHT INTO
WED. A LOW LEVEL JET SHOULD TRANSPORT RATHER ABUNDANT MOISTURE INTO
THE REGION WITH PW FORECAST TO INCREASE TO AROUND 1.4 TO 1.5 INCHES.
THE UPPER LEVEL LOW WILL GRADUALLY OPEN UP WITH A SHORTWAVE TROUGH
WORKING ACROSS EASTERN KY LATER ON WED INTO WED NIGHT. MODELS BRING
SOME INCREASING WINDS ALOFT INTO THE AREA AT THAT POINT...THOUGH THE
STRONGER SHEAR SHOULD REMAIN TO OUR NORTH. THE UPPER LEVEL LOW SHOULD
WORK SLOWLY EAST SOUTHEAST REACHING THE UPPER OH VALLEY REGION AND
MID ATLANTIC STATES THU NIGHT INTO FRIDAY. AT THE SFC...THE LOW WILL
TRACK INTO THE EASTERN GREAT LAKES WED NIGHT AND THEN NORTHEAST
ACROSS THE ST LAWRENCE VALLEY WITH THE TRAILING COLD FRONT CROSSING
EASTERN KY ON THU.
THERE WILL PROBABLY BE A LULL IN CONVECTION FOR A TIME ON TUE NIGHT
BETWEEN RATHER DIURNALLY DRIVEN CONFECTION FROM TUE AND RESURGENCE
LIKELY TO OUR WEST AND SOUTHWEST WITH STRENGTHENING LOW LEVEL JET AND
APPROACHING UPPER LEVEL SHORTWAVE LATE TUE NIGHT. MODEL FORECAST
INSTABILITY AND SHEAR ALONG WITH TIMING OF MODELS BRINGING PREFRONTAL
CONVECTION INTO EASTERN KY POINT TOWARD THE POSSIBILITY OF STRONG TO
LOCALLY SEVERE STORMS POSSIBLE ANYWHERE IN THE CWA THOUGH THE NORTH
WILL BE CLOSER TO THE STRONGER LOW LEVEL JET CORE AS HIGHLIGHTED BY
SPC DAY 3 OUTLOOK. THE POTENTIAL FOR LOCALLY HEAVY RAIN AND SOME OF
THE STORMS TO BECOME STRONG WILL BE HIGHLIGHTED FOR WED IN THE HWO.
LIKELY POPS WERE USED FOR WED IN LINE WITH THE MODEL CONSENSUS AND
MOS GUIDANCE. THE MAV NUMBERS CONTINUE TO APPEAR TOO WARM UNLESS
THERE ENDS UP BEING LITTLE CLOUD COVER ON WED AND HIGH TEMPS WERE
TRENDED LOWER TOWARD MODEL CONSENSUS/MET GUIDANCE.
POPS WERE CONTINUED BEHIND THE BOUNDARY INTO FRI AS THE UPPER LEVEL
SYSTEM GRADUALLY WORKS ACROSS THE REGION. THE EXTENDED MODELS
APPEAR TO BE A IN A BIT BETTER AGREEMENT WITH THE UPPER LEVEL
LOW/SHORTWAVE TROUGH TO MOVE ACROSS THE AREA THU INTO FRI.
HOWEVER...LATER IN THE PERIOD THE GFS MAY BE SUFFERING FROM SOME
CONVECTIVE FEEDBACK ISSUES ACROSS THE PLAINS TO WESTERN GREAT LAKES
REGION SAT INTO SUN WHILE THE ECMWF CONTINUES TO DEVELOP CONVECTION
WITH DISTURBANCES IN NW FLOW INTERACTING WITH A WARM FRONT ADVANCING
TOWARD THE LOWER OH VALLEY REGION LATE IN THE PERIOD. THE EXTENDED
GRID LOAD MODEL CONSENSUS HAD SLIGHT CHANCE TO CHANCE POPS FOR SUN
AND THIS WAS GENERALLY FOLLOWED.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 727 AM EDT MON MAY 20 2013
PATCHY IFR OR WORSE FOG WILL MIX OUT OF THE DEEPER RIVER VALLEYS
THROUGH THE MID-MORNING HOURS. A FEW SHOWERS OR THUNDERSTORMS WILL
BE POSSIBLE DURING PEAK HEATING...HOWEVER THESE SHOULD BE ISOLATED
ENOUGH TO LEAVE OUT THE MENTION AT THE TAF SITES. MVFR FOG WILL
THREATEN LATE TONIGHT ONCE AGAIN.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SBH
SHORT TERM...GEOGERIAN
LONG TERM...JP
AVIATION...GEOGERIAN
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
412 PM EDT MON MAY 20 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 409 PM EDT MON MAY 20 2013
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CLOSED UPR LO OVER
THE NRN PLAINS UPSTREAM OF UPR RDG EXTENDING FM THE CENTRAL GRT LKS
INTO THE SE CONUS. DRY SLOTTING ALF TO THE E OF THIS FEATURE AS
SHOWN BY HIER 12Z H85 AND H7 DEWPT DEPRESSIONS AT GRB/DAVENPORT IA
HAS TENDED TO STUNT SHRA DVLPMENT OVER THE W HALF OF THE CWA...BUT
MORE PERSISTENT AXIS OF GREATER MSTR/HIER KINX OVER THE ERN CWA AND
SHRTWV MOVING NE FM WI HAS LED TO MORE SHRA/ELEVATED TS IN THAT
AREA. LO CLDS HAVE LINGERED N OF SFC WARM FNT AS WELL EXCEPT OVER
THE W...WHERE SOME LLVL DRYING/DAYTIME HEATING HAVE TENDED TO MIX
OUT THE LO CLDS AND BOOST TEMPS INTO THE 70S. TO THE W...12Z MPX
RAOB SHOWS A MUCH MOISTER AIRMASS. SOME SHRA ARE DVLPG IN WRN WI
WITH DAYTIME HEATING/DESTABILIZATION ON THE ERN EDGE OF THIS DEEPER
MSTR. FARTHER TO THE SW...ANOTHER SHRTWV IS ROTATING ARND THE CLOSED
LO AND THRU THE SCENTRAL PLAINS.
CHALLENGING FCST THRU THE SHORT TERM. BUT WITH CUTOFF LO SWIRLING TO
THE W...TENDED TO FOLLOW THE LEAST PROGRESSIVE MODELS FOR FCST
PREPARATION.
TNGT...EXPECT UPR DRY SLOT TO BRING A RELATIVELY QUIET LATE AFTN/
EARLY EVNG TIME TO THE CWA PER MOST OF RECENT HI RES GUIDANCE.
EXPECT LINGERING SHRA/TS OVER THE E TO END LATE THIS AFTN WITH
DRYING AT H85-7 SLOWLY PUSHING AXIS OF HIER MSTR TO THE E. SHRA NOW
DVLPG IN WRN WI E OF MOISTER AIRMASS SHOWN ON THE 12Z MPX RAOB AND
NEAR THE WRN EDGE OF THE DRY SLOT MAY IMPACT THE WRN ZNS THIS EVNG
AS THEY DRIFT NWD IN THE SLY FLOW ALF E OF THE UPR LO...SO CARRIED
CHC POPS IN THIS AREA THRU THE EVNG. LATER TNGT...PREFERRED 12Z
GFS/REG CNDN MODELS SHOW MORE SHRA/TS ARRIVING OVER THE SCENTRAL
COUNTIES AS SHRTWV NOW MOVING THRU THE SCENTRAL PLAINS ACCOMPANIED
BY JET MAX/UPR DVGC CORE ROTATES NEWD AHEAD OF THE NEARLY STNRY
CLOSED LO TO THE W. FCST LIKELY POPS ARRIVING LATE IN THIS AREA.
OTRW..TENDED TOWARD THE HIER END OF GUIDANCE FOR MIN TEMPS EXCEPT
NEAR THE GREAT LKS.
TUE...SHRA/SOME TS ASSOCIATED WITH DISTURBANCE LIFTING NEWD E OF THE
MAIN CLOSED LO WL IMPACT MAINLY THE CENTRAL/ERN ZNS IN THE MRNG
BEFORE GIVING WAY TO MID LVL DRYING. APRCH OF ANOTHER DISTURBANCE FM
THE SSW ROTATING ARND THE CLOSED LO MAY BRING ANOTHER BATCH OF
SHRA/TS NEAR THE WI BORDER LATER IN THE DAY. HI TEMPS FCST WL BE
TRICKY. THE CNDN MODEL HINTS AT MORE OF A SFC WAVE RIDING THRU THE
ECENTRAL AND HINTS THERE COULD BE MORE SUNSHINE IN THIS AREA IN THE
AFTN. RIGHT NOW...PLAYED THE FCST FOR MORE CLDS/A LLVL NE FLOW OFF
THE COOL WATERS OF LK SUP TO THE N OF STNRY FNT JUST TO THE W.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 409 PM EDT MON MAY 20 2013
THE FOCUS OF THE LONG TERM FORECAST THIS WEEK WILL BE THE PASSING OF
A LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES REGION. CLOSED 500MB
LOW OVER THE NORTHERN PLAINS THIS AFTERNOON WILL MAKE ITS WAY JUST
SOUTH OF UPPER MICHIGAN ON WEDNESDAY...GRADUALLY FILLING AS IT
REACHES THE EASTERN SEABOARD BY FRIDAY AFTERNOON. THIS LOW EXTENDS
FROM A TROUGH ASSOCIATED WITH STRONGER LOW PRESSURE SITUATED OVER
NORTHERN QUEBEC. AT THE 300MB LEVEL LEFT EXIT REGION DIVERGENCE HAS
HELPED WITH THE DEVELOPMENT OF THE LOW PRESSURE SYSTEM OVER THE
PLAINS. THIS JET WILL SHIFT NORTHWARD AND BY WEDNESDAY UPPER
MICHIGAN WILL BE SLIGHTLY NORTH OF THE BEST UPPER LEVEL SUPPORT...IN
THE RIGHT ENTRANCE REGION. 850-500MB QVECTOR CONVERGENCE SHOWS BEST
LIFT GENERALLY ALONG SOUTHWESTERN-SOUTHERN UPPER MI/LOWER
MI/WISCONSIN ACCORDINGLY. MEANWHILE...A WEAK SURFACE LOW DEVELOPING
IN THE PLAINS MOVES NORTHWARD ALONG THE TROUGH...PASSING THROUGH
LOWER MI AND THE LOWER GREAT LAKES WEDNESDAY AFTERNOON INTO
WEDNESDAY NIGHT. MODEL SOUNDINGS SHOW ABUNDANT MOISTURE REMAINS
THROUGH ALL OF WEDNESDAY FOR CENTRAL/EASTERN UPPER MI BEFORE THE
VERY DRY AIRMASS/HIGH PRESSURE ARRIVES WEDNESDAY NIGHT/THURSDAY.
PWATS DURING THIS TIME STILL REMAIN AS HIGH AS 150 PERCENT OF
NORMAL. HAVE A DIMINISHING TREND FOR POPS FROM WEDNESDAY AFTERNOON
ONWARD AS DRY AIR INFILTRATES THE AREA AND THE SFC LOW EXITS THE
REGION. ADDITIONALLY...WITH ABUNDANT MOISTURE IN PLACE EXPECTING FOG
ACROSS LAKE SUPERIOR AND LAKE MICHIGAN FOR TUESDAY NIGHT/EARLY
WEDNESDAY AFTERNOON. ONCE THE DRIER AIR MOVES IN THE FOG WILL
DISSIPATE.
UPPER LEVEL HIGH OVER THE CANADIAN PRAIRIE WILL SINK SOUTHWARD AND
MERGE WITH THE BUILDING RIDGE OVER THE CENTRAL UNITED STATES ON
THURSDAY MORNING...BRINGING AN END TO PRECIPITATION FOR UPPER MI.
WITH DRY AIR SCOURING OUT THE CLOUDS...NORTHERLY WINDS...AND 850MB
TEMPS AROUND 2-4C...THURSDAY AFTERNOON LOOKS TO BE MOSTLY SUNNY WITH
TEMPS IN THE MID-UPPER 50S AND MAYBE EVEN LOW 60S....BELOW NORMAL BY
LATE MAY STANDARDS. MIXED LAYER DEWPOINTS BRING DEWPOINTS INTO THE
UPPER 20S/30S WHICH BRINGS MINIMUM RH FIELDS TO 30-40 PERCENT FOR
MID AFTERNOON ON THURSDAY.
A SHORTWAVE ROTATING AROUND THE 500MB LOW IN QUEBEC WILL PASS
OVERHEAD FRIDAY AFTERNOON BUT WITH DRY AIR FIRMLY IN PLACE NOTHING
WILL COME OF IT BEYOND SOME SCATTERED CLOUDS. AFTER FRIDAY THE UPPER
LEVEL RIDGE WILL SPRAWL ACROSS MUCH OF THE CENTRAL AND EASTERN
UNITED STATES. THIS WILL KEEP A DRIER AIRMASS IN PLACE AND KEEP
CONDITIONS QUIET THROUGH SATURDAY AFTERNOON. A LOW PRESSURE
TROUGH/SHORTWAVE WILL MOVE INTO THE GREAT LAKES AREA SATURDAY
EVENING INTO MONDAY...BRINGING A CHANCE FOR RAIN SHOWERS INTO THE
CWA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 134 PM EDT MON MAY 20 2013
CHALLENING AVIATION FCST TODAY. BUT WITH CWA N OF SFC WARM FNT AND
STEADY UPSLOPE E-SE WIND...EXPECT PREDOMINANT IFR CONDITIONS TO
PERSIST THRU THE FCST PERIOD AT SAW AND ESPECIALLY CMX...WHERE
LIFR/VLIFR CONDITIONS WL PREVAIL INTO THIS EVNG. DOWNSLOPING FLOW
AND DAYTIME HEATING/MIXING SHOULD MAINTAIN VFR CONDITIONS AT IWD
THRU THE AFTN...BUT EXPECTED WSHFT TO THE NE OFF COOL/MOIST LK SUP
THIS EVNG/TUE SHOULD BRING IFR CONDITIONS OVER THAT SITE.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 409 PM EDT MON MAY 20 2013
NE GALES OVER FAR WESTERN LAKE SUP WITH FAVORABLE TERRAIN FUNNELING
OF THAT FLOW WILL TEND TO DIMINISH TO 20 TO 25 KT THIS EVENING WITH
WEAKENING PRES GRADIENT. WILL LET GALE WARNING EXPIRE AT 03Z.
OTHERWISE...EXPECT PATCHY FOG TO SLOWLY DISSIPATE FROM THE N BY
LATER TUE WITH GRADUAL ARRIVAL OF DRIER AIR IN PERSISTENT NE FLOW TO
THE S OF HI PRES OVER ONTARIO.
A LOW PRESSURE SYSTEM WILL PASS JUST SOUTH OF LAKE SUPERIOR
WEDNESDAY. WINDS WILL BECOME MORE NORTHERLY AS THE LOW MOVES EASTWARD
ON THURSDAY BUT ARE EXPECTED TO REMAIN LESS THAN 25 KNOTS. HIGH
PRESSURE WILL FILTER IN BEHIND THE LOW THURSDAY EVENING AND REMAIN
THROUGH THE WEEKEND...KEEPING WINDS GENERALLY LESS THAN 20 KNOTS. &&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 11 PM EDT /10 PM CDT/ THIS EVENING FOR LSZ162.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MCD
AVIATION...KC
MARINE...MCD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
136 PM EDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1000 AM EDT MON MAY 20 2013
BASED ON DRYNESS ARND H85 AS SHOWN ON THE 12Z GRB RAOB...WHERE THE
H85 DEWPT DEPRESSION WAS 11C...TENDED TO TRIM POPS A BIT FOR TODAY.
LATEST RUC MODEL SHOWS THIS DRY AIR OVERSPREADING THE CWA THRU THE
AFTN. MAINTAINED THE HIER CHC POPS OVER THE E HALF OF THE CWA...
WHERE HIER H85 DEWPTS ARE PROGGED TO LINGER LONGER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 449 AM EDT MON MAY 20 2013
UPPER AIR PATTERN CONSISTS OF A CLOSED 500 MB LOW OVER SD WITH A
DEEP TROUGH ACROSS THE PLAINS STATES AND A 500 MB RIDGE IN THE UPPER
GREAT LAKES. THE RIDGE GETS PUSHED FURTHER TO THE EAST OVER THE
LOWER GREAT LAKES THIS FORECAST PERIOD WHILE THE TROUGH HEADS SLOWLY
EAST WITH THE 500 MB LOW NOT MOVING VERY MUCH AT ALL.
850-500 MB Q-VECTOR CONVERGENCE AND DEEP MOISTURE REMAIN FOR THIS
FORECAST PERIOD AND THE NAM...ECMWF AND GFS SHOW THIS. TRICKY
FORECAST COMING UP WITH AMOUNT OF CLOUD COVER DUE TO CONVECTION
BEING HARD TO DETERMINE AND THIS OF COURSE WILL HAVE AN EFFECT ON
TEMPERATURES. THE MORE SUN THAT WE SEE...THE WARMER THE TEMPERATURES
WILL BE AND THE GREATER THE INSTABILITY FOR THE THUNDERSTORMS TO
WORK WITH. TEMPERATURES HAVE A BIG BUST POTENTIAL FOR TODAY WITH
CLOUD COVER BEING THE BIG QUESTION. THOUGHT THERE WOULD BE SOME
LIMITED SUNSHINE AND ENDED UP WARMING HIGH TEMPERATURES A FEW
DEGREES...ESPECIALLY OVER THE EAST WHERE THAT AREA IS FURTHER FROM
THE STRONG FORCING AND HAS SOME DRIER AIR AWAY FROM THE SFC WARM
FRONT. DID GRADUALLY BRING HIGH POPS OVER THE CWA TODAY AS SYSTEM
DRAWS CLOSER AND KEPT LIKELY POPS IN FOR TONIGHT AS THERE WILL
PROBABLY BE AN MCS/MCC IN THE AREA BRINGING WIDESPREAD RAINFALL TO
THE AREA. DID NOT HAVE ANY TIME TO LOOK AT SEVERE WEATHER
POTENTIAL...BUT THINKING IS THERE COULD BE A FEW STORMS WITH STRONG
WINDS AND LARGE HAIL AND THE SLIGHT RISK ACROSS THE SOUTHERN CWA
LOOKED REASONABLE. ALL DEPENDS ON AMOUNT OF SUNSHINE SEEN TO THE
SOUTH OF THE AREA AND THAT IS THE QUESTION THAT CANNOT BE ANSWERED
AT THIS TIME.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 515 AM EDT MON MAY 20 2013
THE NEARLY STEADY STATE 500MB LOW TO OUR WEST WILL CONTINUE TO SPIN
ACROSS THE EASTERN DAKOTAS AND WESTERN MN AT 12Z TUESDAY. EXPECT THE
LOW TO SLIDE EASTWARD ON WEDNESDAY...MERGING WITH THE STRONGER LOW
SPINNING OVER EASTERN HUDSON BAY/NORTHERN QUEBEC. THE BEST CHANCE
FOR CONVECTION WILL LINGER ACROSS THE WI BORDER TUESDAY INTO TUESDAY
EVENING...BEFORE SLOWLY COMING TO AN END. FOG OVER LAKE SUPERIOR
WILL SLOWLY BEGIN TO PUSH TO FAR SOUTHERN PORTIONS OF THE
LAKE...WITH LAKE MICHIGAN FOG LIKELY REMAINING STRONG THROUGH MUCH
OF WEDNESDAY WHEN THE DEEPER MOISTURE EXITS THE REGION.
EXPECT COOL NORTHERLY FLOW TO BE THE RULE FROM THURSDAY ON...AS THE
REINFORCING 500MB TROUGH PUSHES IN FROM THE NW. THE LAST OF THE RAIN
SHOULD BE EXITING EASTERN UPPER MI THURSDAY MORNING. DRY WEATHER
SHOULD BE THE RULE FROM THURSDAY AFTERNOON THROUGH AT LEAST THE END
OF THE FORECAST PERIOD /SUNDAY/...AS HIGH PRESSURE DOMINATES THE
REGION.
850MB TEMPS OFF THE 19/12Z ECMWF FALL TO A RATHER COOL 0 TO -3C
THURSDAY NIGHT INTO EARLY FRIDAY...AS COOL HIGH PRESSURE SINKS IN
FROM THE NNW. THE 20/00Z RUN WARMED UP SLIGHTLY AND LINED UP A BIT
BETTER WITH THE GFS...AROUND 0 TO 2C FRIDAY THROUGH SATURDAY. THE
NORMAL HIGH TEMPS FOR THIS TIME OF YEAR ARE IN THE MID 60S FOR MUCH
OF THE CWA...TO NEAR 70F SOUTH CENTRAL AND NEAR THE WI BORDER. WE
SHOULD BE WELL BELOW NORMAL FOR HIGH TEMPS...IN THE 50S ON THURSDAY.
FRIDAY WILL NOT BE MUCH WARMER...WITH A FEW READINGS IN THE LOW TO
MID 60S NEAR THE WI BORDER.
A HIGH AMPLITUDE RIDGE ACROSS THE CENTRAL U.S. UP THROUGH CENTRAL
CANADA WILL CONTINUE TO BUILD...THANKS THE THE BOOKEND 500MB LOWS
OVER THE PACIFIC NORTHWEST AND ACROSS QUEBEC. LOOK FOR THIS RIDGE TO
SLOWLY EDGE EASTWARD...AND RIGHT ACROSS WI/MN/WESTERN UPPER MI AND
LAKE SUPERIOR BY DAYBREAK MONDAY. WARMER AIR WILL SLOWLY CREEP BACK
IN...BUT WITH NO GREAT SOUTHERLY RETURN FLOW...TEMPERATURES WILL
ONLY MODERATE SLIGHTLY EACH DAY...WITH BELOW NORMAL READINGS AND
RELATIVELY LIGHT WINDS STILL BY SUNDAY AS THE LARGE/STRONG HIGH
PRESSURE SYSTEM CENTERED OVER MUCH OF ONTARIO SINKS CLOSER TO THE
AREA. WHILE BOTH THE GFS AND ECMWF HINT AT A COUPLE OF SHORTWAVES
SINKING IN ON THE NW FLOW ALOFT OVER THE UPCOMING WEEKEND. AT THIS
POINT THERE DOESN/T LOOK TO BE ENOUGH MOISTURE AROUND TO RESULT IN
ANYTHING MORE THAN A FEW CLOUDS. IF ANY SHOWERS OR TS DEVELOP...THEY
WILL LIKELY REMAIN NORTH AND EAST...CLOSER TO THE 500MB AND SFC LOW
ACROSS QUEBEC.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 134 PM EDT MON MAY 20 2013
CHALLENING AVIATION FCST TODAY. BUT WITH CWA N OF SFC WARM FNT AND
STEADY UPSLOPE E-SE WIND...EXPECT PREDOMINANT IFR CONDITIONS TO
PERSIST THRU THE FCST PERIOD AT SAW AND ESPECIALLY CMX...WHERE
LIFR/VLIFR CONDITIONS WL PREVAIL INTO THIS EVNG. DOWNSLOPING FLOW
AND DAYTIME HEATING/MIXING SHOULD MAINTAIN VFR CONDITIONS AT IWD
THRU THE AFTN...BUT EXPECTED WSHFT TO THE NE OFF COOL/MOIST LK SUP
THIS EVNG/TUE SHOULD BRING IFR CONDITIONS OVER THAT SITE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 449 AM EDT MON MAY 20 2013
THE MAIN THREATS FOR THIS PERIOD WILL BE A FEW HIGHER GUSTS AT THE
HIGHEST OBSERVING PLATFORMS...AND THE POTENTIAL FOR FOG. A FEW GUSTS
OF 30-35KTS POSSIBLE THROUGH MONDAY...WITH MOST SITES ABOUT 10KTS
LOWER THANKS TO THE MARINE LAYER. HAVE ALREADY HAD REPORTS OF AROUND
2-5SM VIS OVER W LAKE SUPERIOR...WHICH WILL LIKELY CONTINUE AND
SLOWLY SPREAD E WITH THE BETTER CHANCE OF SHOWERS TODAY. EXPECT FOG
TO LINGER THROUGH TUESDAY /FOR MAINLY S LAKE SUPERIOR/.
EXPECT A RIDGE OVER N MANITOBA TO SLIDE ACROSS JAMES BAY
TONIGHT...AND EXIT E ACROSS QUEBEC TUESDAY NIGHT. IN THE
MEANTIME...A LOW OVER THE EASTERN DAKOTAS AND WESTERN MINNESOTA
TODAY AND TONIGHT SHOULD FILL SLIGHTLY ACROSS SOUTHERN MINNESOTA AND
CENTRAL WISCONSIN ON TUESDAY...AND SLOWLY OVER STRETCHING FROM
SOUTHERN WISCONSIN TO LOWER MICHIGAN DURING THE DAY WEDNESDAY. THE
LOW WILL FINALLY EXIT E ACROSS THE LOWER GREAT LAKES WEDNESDAY
NIGHT. BEHIND THE LOW...STRONG AND COOL HIGH PRESSURE ACROSS N
CENTRAL CANADA WILL EXTEND A RIDGE ACROSS LAKE SUPERIOR LATE
THURSDAY AFTERNOON THROUGH AT LEAST FRIDAY...AND MOST LIKELY THROUGH
THE WEEKEND.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 11 PM EDT /10 PM CDT/ THIS EVENING FOR LSZ162.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...KC
SHORT TERM...07
LONG TERM...KF
AVIATION...KC
MARINE...KF
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
116 PM EDT MON MAY 20 2013
LATEST UPDATE...
AVIATION
.SYNOPSIS...
ISSUED AT 330 AM EDT MON MAY 20 2013
A SLOW MOVING LOW PRESSURE SYSTEM WILL BRING SHOWERS AND
THUNDERSTORMS TO SOUTHERN LOWER MICHIGAN TODAY THROUGH WEDNESDAY. A
FEW STRONG TO SEVERE STORMS ARE POSSIBLE DAILY. COOLER AIR WILL MOVE
IN LATE THIS WEEK.
&&
.UPDATE...
ISSUED AT 1120 AM EDT MON MAY 20 2013
LOW CONFIDENCE SEVERE WEATHER WILL DEVELOP THIS AFTERNOON. SOME
STORMS STILL LOOK LIKE THEY WILL FIRE AT SOME POINT TODAY...THOUGH
EXPECTATIONS ARE THAT A WIDESPREAD SEVERE EVENT WILL NOT OCCUR
THIS AFTERNOON. SOME ADJUSTMENTS TO PRECIPITATION CHANCES THIS
MORNING...OTHERWISE REMAINING FORECAST LEFT ALONE WITH THIS
UPDATE.
SLIGHTLY MORE FAVORABLE SET UP SEEMS TO OCCUR THIS EVENING AND
EARLY TONIGHT AND TUESDAY.
UPDATE ISSUED AT 744 AM EDT MON MAY 20 2013
THAT BAND OF SHOWERS AND ISOLATED THUNDERSTORMS HAS NOW MOVED OUT
OF THE AREA SO I LOWERED POPS THROUGH THE MID MORNING HOURS OVER
THE NORTHERN CWA. THAT WAS ASSOCIATED WITH THE 850 MB WARM FRONT...
WHICH IS NOW NORTH OF THE CWA. IT STILL LOOKS LIKE THE ENERGY FROM
THE CONVECTION SOUTHWEST OF CHICAGO SHOULD REACH OUR CWA EARLY
THIS AFTERNOON TOUCHING OFF A SERIES OF STORMS EARLY TO MID
AFTERNOON.
OVERNIGHT TONIGHT THE LOW LEVEL JET IS AIMED AT SOUTHWEST MICHIGAN
SO I EXPECT ANOTHER PERIOD OF THUNDERSTORMS AFTER MIDNIGHT.
UPDATE ISSUED AT 518 AM EDT MON MAY 20 2013
A FEW SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO DEVELOP ON
THE WARM FRONT FROM BIG SABLE POINT TO NORTHEAST KENT COUNTY AS OF
515 AM THIS MORNING. THE STORMS ARE MOVING NORTHEAST AROUND 40 MPH.
WHILE RAP SOUNDINGS DO SHOW OVER AROUND 100 J/KG OF CIN THERE IS
NEARLY 1000 J/KG OF CAPE ONCE THE CIN IS OVERCOME. I EXPECT THE
STORMS TO CONTINUE TO LIFT NORTH AND EAST OUT OF THE CWA BY 9 AM
THIS MORNING. BASED ON THIS I UPDATED THE GRIDS AND ZONES TO
INDICATE POSSIBLE THUNDERSTORMS FROM I-96 NORTH INTO MID MORNING.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY AFTERNOON)
ISSUED AT 330 AM EDT MON MAY 20 2013
PRIMARY SHORT TERM FCST CONCERNS INVOLVE EVALUATION OF
CONVECTIVE/SVR WX POTENTIAL TODAY THROUGH WEDNESDAY.
A WARM FRONT LIFTING NORTH ACROSS OUR AREA LATER TODAY AND
INCREASING INSTABILITY WILL LEAD TO THE DEVELOPMENT OF SHOWERS AND
STORMS. SOME STRONG TO SEVERE STORMS ARE POSSIBLE PARTICULARLY THIS
AFTERNOON AND EVENING AS SB CAPE VALUES POTENTIALLY REACH AROUND
2000-3000 J/KG NEAR TO SOUTH OF I-96 ALONG WITH STRONGLY NEGATIVE
LI/S AND TOTAL TOTALS INDICES INTO THE MID TO UPPER 50S.
SOME 00Z GUIDANCE FCST SOUNDINGS HAVE AN INVERTED V LOOK BY LATER
THIS AFTN/EVENING SO THERE IS POTENTIAL FOR STRONG TO SEVERE STORMS
TO PRODUCE DAMAGING WIND GUSTS. IN ADDITION LARGE HAIL IS ALSO
POSSIBLE BOTH WITH SFC BASED STORMS AND WITH ELEVATED CONVECTION
NORTH OF THE WARM FRONT. CANNOT RULE OUT AN ISOLATED TORNADO NEAR TO
SOUTH OF THE WARM FRONT THIS AFTERNOON AND EVENING ALTHOUGH THIS
POTENTIAL IS MITIGATED SOMEWHAT BY FAIRLY HIGH LCL HEIGHTS.
SCATTERED STRONG TO POTENTIALLY SVR STORMS ARE POSSIBLE AGAIN
TUESDAY ALTHOUGH WE STILL FEEL THAT POTENTIAL TOMORROW IS NOT AS
GREAT AS LATER TODAY WITH A CONSENSUS OF LATEST 00Z GUIDANCE SHOWING
LESS INSTABILITY/MUCH MORE CLOUD COVER AROUND. THE SVR WX THREAT
TUESDAY WILL BE LARGELY CONTINGENT ON HOW CONVECTIVE EVOLUTION
OCCURS TONIGHT AND ON EXTENT ON CLOUD COVER.
THE SEVERE WX THREAT CONTINUES WEDNESDAY AS THE SFC LOW FINALLY
MOVES EAST INTO MICHIGAN AND AS THE UPPER LEVEL SUPPORT/UPPER TROF
AND ASSOCIATED COLD POOL OF AIR ALOFT MOVE IN. THE 12Z ECMWF/00Z GFS
IN PARTICULAR SUGGEST DECENT SVR WX POTENTIAL WEDNESDAY GIVEN THE
TIMING OF THE SFC LOW AND FRONTAL POSITIONS THROUGH OUR REGION. ALL
THINGS CONSIDERED AT THIS TIME WE BELIEVE THE BEST CHC FOR ORGANIZED
SVR WX WILL BE WEDNESDAY.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 330 AM EDT MON MAY 20 2013
THE RAIN SHOWERS SHOULD COME TO AN END BY LATE IN THE DAY THURSDAY.
BY THEN THE THREAT FOR THUNDERSTORMS WILL BE SOUTH OF MICHIGAN. A
CANADIAN HIGH WILL MOVE IN FOR THE FRIDAY INTO SATURDAY TIME FRAME.
THIS BRINGS CANADIAN POLAR AIR SOUTH WITH IT SO THERE IS A THE
THREAT OF FROST OVER THE NORTHERN TWO ROWS OF COUNTIES EARLY
SATURDAY MORNING. ANOTHER PACIFIC STORM WILL LIKELY TO TRACK SOUTH
OF THE AREA BUT WILL BRING THE TREAT OF A LIGHT RAIN SHOWERS SUNDAY.
CONFIDENCE IN THIS FORECAST IS ABOUT AVERAGE. THE MODELS ALL AGREE
ON THE OVERALL PATTERN INTO NEXT WEEK. THERE ARE MINOR ISSUES IN THE
DETAILS BUT LITTLE QUESTION THE SYSTEM OVER US NOW WILL BE SHEARED
OUT TO THE EAST BY FRIDAY MORNING. THE LONGWAVE RIDGE WILL SURELY
BUILD TO OUR WEST BEHIND THE DEPARTING SYSTEM. THAT WILL BRING IN
COOLER AIR FRIDAY INTO SATURDAY. THE UPPER RIDGE TO OUR WEST WILL
THEN SLOWLY BUILD EAST OVER TIME PUSHING THE COLD AIR OUT ONCE AGAIN
(EARLY NEXT WEEK). THERE IS SOME QUESTION AS TO WHAT HAPPENS THE
SOME OF THAT PACIFIC SHORTWAVE ENERGY OVER THE WEEKEND AS THE WARM
AIR PUSHES TOWARD US. THE ECMWF KEEPS THE PRECIPITATION SOUTH OF
MICHIGAN THROUGH THE WEEKEND AND THE GFS BRINGS IT IN SUNDAY. I HAVE
LOW CHANCE POPS FOR THAT BUT I AM CURRENTLY THINKING THIS WILL
ACTUALLY MISS US TO THE SOUTH JUST LIKE THE ECMWF SUGGEST.
THE RAIN ON THURSDAY IS DEFORMATION ZONE RELATED AS THE SYSTEM
SHEARS OUT TO THE EAST BUT THERE IS LITTLE OF ANY INSTABILITY WITH
THIS... JUST SHOWERS. THE CONVECTIVE THREAT IS LARGELY OVER BY MID
EVENING WEDNESDAY.
AS FOR THE FROST THREAT... WITH THE CANADIAN HIGH BUILDING IN FRIDAY
INTO SATURDAY... WINDS WILL BECOME LIGHT AND VARIABLE EARLY SATURDAY
MORNING AND SKIES WILL BE CLEAR. DEW POINTS LIKELY WILL FALL INTO
THE LOWER TO MID 30S SO A GOOD SET UP FOR FROST OVER THE NORTHEAST
COUNTIES. AREAS SOUTH OF ROUTE 10 SHOULD STAY WARM ENOUGH FOR THIS
NOT TO BE AN ISSUE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 116 PM EDT MON MAY 20 2013
THE MAIN FOCUS OF THE 18Z SET OF FCSTS IS CONVECTION TRENDS
THROUGH THE PERIOD.
A FEW ISOLATED STORMS ARE GOING UP AS OF 1715Z THIS AFTERNOON.
THESE FORMED JUST EAST OF KMKG AND ARE MOVING NORTHEAST AND
STAYING NORTH OF THE REMAINDER OF THE TERMINALS. THERE COULD BE
MORE STORMS THAT FORM NEAR THE LAKESHORE AND MOVE INLAND...BUT
CONFIDENCE IS STILL LIMITED AS TO WHERE ADDITIONAL STORMS...IF ANY
WILL FIRE THIS AFTERNOON. WE HAVE VCTS TO ADDRESS THE CONVECTION
CHCS AND UNCERTAINTY. WE WILL UPDATE THE FCSTS AS NECESSARY IF
CONVECTION IS HEADING TOWARD A SITE. MVFR CONDITIONS CAN BE
EXPECTED UNDER ANY STORMS WITH SOME BRIEF BOUTS OF IFR POSSIBLE.
THE NEXT ROUND OF STORMS SHOULD COME IN AS EARLY AS LATER THIS
EVENING...AND MORE SO OVERNIGHT. THESE STORMS LOOK LIKE THEY WILL
BE MORE WIDESPREAD AND AFFECT ALL OF THE SITES. AGAIN MVFR SHOULD
BE EXPECTED UNDER ANY STORMS WITH BRIEF PERIODS OF IFR ALSO
LIKELY. WE WILL CONTINUE TO FINE TUNE THE CONVECTION OVERNIGHT.
&&
.MARINE...
ISSUED AT 744 AM EDT MON MAY 20 2013
DUE TO THE WATER TEMPERATURES OFF SHORE OF LAKE MICHIGAN ARE IN
THE MID 40S... AND SURFACE DEW POINTS ARE IN THE 60S TODAY PLUS
WINDS ARE NOT ALL THAT STRONG... I EXPECT EXTENSIVE FOG IN THE
NEAR SHORE TO DEVELOP. SO EXPANDED THE FOG INTO THIS AFTERNOON.
&&
.FIRE WEATHER...
ISSUED AT 330 AM EDT MON MAY 20 2013
WARM AND FAIRLY HUMID WEATHER IS EXPECTED TODAY THROUGH WEDNESDAY.
THUNDERSTORMS WILL BRING LIGHTNING AND GUSTY WINDS AT TIMES TODAY
THROUGH WEDNESDAY.
&&
.HYDROLOGY...
ISSUED AT 330 AM EDT MON MAY 20 2013
SEVERAL ROUNDS OF RAIN AND THUNDERSTORMS ARE EXPECTED TODAY THROUGH
WEDNESDAY BUT SIGNIFICANT FLOODING IS NOT ANTICIPATED SINCE
CUMULATIVE RAINFALL AMOUNTS ON AVERAGE OF ONLY AROUND AN INCH OR TWO
ARE ANTICIPATED THROUGH WEDNESDAY NIGHT. HOWEVER LOCALIZED FLOODING
ISSUES MAY OCCUR WITH HEAVIEST STORMS OR WHERE STORMS TRACK ACROSS
THE SAME LOCATION.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.
&&
$$
UPDATE...MACZKO
SYNOPSIS...LAURENS
SHORT TERM...LAURENS
LONG TERM...WDM
AVIATION...NJJ
FIRE WEATHER...LAURENS
HYDROLOGY...LAURENS
MARINE...WDM
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
352 PM CDT MON MAY 20 2013
.SHORT TERM...(THROUGH LATE TONIGHT)
ISSUED AT 323 PM CDT MON MAY 20 2013
ALL SYSTEMS APPEAR GO FOR AN ACTIVE NIGHT OF THUNDERSTORMS WITH
SEVERE POTENTIAL AS THE ENVIRONMENT WILL HAVE PLENTY OF INSTABILITY
AND DEEP LAYER SHEAR AROUND 50 KTS. THE AIR MASS OVER THE SOUTHERN
HALF OF MISSOURI HAS RECOVERED FROM EARLIER CONVECTION WITH SBCAPE
AOA 3000 J/KG AND THIS RECOVERY SHOULD CONTINUE TO SPREAD
NORTHWARD THROUGH THE LATE AFTERNOON. SCATTERED THUNDERSTORMS HAVE
DEVELOPED IN SEVERAL CONFLUENT ZONES ACROSS SW MO AND SE KS AND
ARE MOVING TO THE NORTHEAST. ADDITIONAL DEVELOPMENT IS EXPECTED
WITH DISCRETE STORMS POSSIBLE THROUGH EARLY EVENING AND THEN AN
OVERALL TREND FOR RAPID UPSCALE GROWTH INTO A FORWARD PROPAGATING
QLCS FEATURING A MIX MODE OF BOWING SEGMENTS AND EMBEDDED
SUPERCELLS. THIS QLCS IS EXPECTED TO IMPACT A GOOD PORTION OF THE
CWA AS IT MOVES E/NW TONIGHT. SOME LOCALLY HEAVY RAINFALL MAY
OCCUR WHERE TRAINING OCCURS...BUT THE SYSTEM IS NOT EXPECTED TO
PRODUCE A WIDESPREAD HEAVY RAIN/FLASH FLOOD THREAT.
GLASS
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY)
ISSUED AT 323 PM CDT MON MAY 20 2013
THE IMPACTS OF THE OVERNIGHT CONVECTION ARE HARD TO GAGE AND WILL
HAVE LARGE RAMIFICATIONS ON THE THUNDERSTORM AND SEVERE THREAT
TUESDAY. ANY ONGOING SHOWERS/THUNDERSTORMS REMNANT FROM OVERNIGHT
ARE LIKELY TO BE LOCATED ACROSS SE MO INTO SW IL DURING THE FIRST
PART OF THE MORNING AND THEN WEAKEN. MODEL GUIDANCE SUGGESTS IT
WILL THEN REMAIN RELATIVELY VOID OF PRECIPITATION WELL INTO MID
AFTERNOON AND THIS SHOULD ALLOW FOR SOME AIR MASS RECOVERY AS
CLOUDS THIN. MID LEVEL LAPSE RATES ARE NOT AS STEEP SO OVERALL
INSTABILITY SHOULD BE LESS THAN THE LAST FEW DAYS...HOWEVER IT SHOULD
BE SUFFICIENT WITH AMPLE DEEP LAYER SHEAR FOR SCATTERED ORGANIZED
THUNDERSTORMS DEVELOPING DURING THE LATER PART OF THE AFTERNOON...RAMPING
UP IN COVERAGE DURING THE EARLY EVENING AS LARGE SCALE ASCENT INCREASES
IN ASSOCIATION WITH A SHORT WAVE ROTATING NEWD FROM EASTERN OK
REGION. ANY RESIDUAL BOUNDARIES WILL PROVIDE FURTHER FOCUS AND
ENHANCE THE SEVERE THREAT. THE LARGE SCALE TROF AND ATTENDANT COLD
FRONT WILL FINALLY MOVE ACROSS THE AREA TUESDAY NIGHT...PASSING
EAST OF THE CWA BY EARLY WEDNESDAY MORNING. DRIER AIR AND COOLER
AIR WILL OVERSPREAD THE AREA ON WEDNESDAY IN THE WAKE OF THE FRONT
AND A SECONDARY COLD FRONT ON WEDNESDAY NIGHT WILL USHER EVEN
COOLER AIR AND HIGH PRESSURE INTO THE AREA.
THE PATTERN WILL BE DOMINATED BY WEAK NW FLOW ON THE BACKSIDE OF
THE UPPER TROF AND LOOKS DRY THURSDAY NIGHT-FRIDAY...THEREAFTER
RETURN FLOW AND WEAK DISTURBANCES PASSING THRU THE PLAINS UPPER
RIDGE AND INTO THE MID/UPPER MS VALLEY WILL BRING A RE-NEWED
CHANCE OF THUNDERSTORMS....ESPECIALLY THE NRN HALF OF THE CWA.
WARMER TEMPERATURES WILL ALSO ACCOMPANY THE RETURN FLOW.
GLASS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 112 PM CDT MON MAY 20 2013
STILL HARD TO PIN DOWN EXACT COVERAGE AND TIMING OF STORMS...SO
KEPT VCTS MENTION AT KCOU THROUGH 03Z TUESDAY AND THROUGH 04Z
TUESDAY AT KUIN. FURTHER EAST OVER STL METRO AREA...HRRR MODEL
INDICATING STORMS TO NOT MOVE IN TIL AFTER 01Z TUESDAY...MAYBE
EVEN LATER...BUT KEPT VCTS MENTION AFTER 01Z TUESDAY FOR
NOW...TAPERING OFF AFTER 07Z TUESDAY. OTHERWISE...EXPECT VFR CIGS AND
GUSTY SOUTH WINDS FOR THIS AFTERNOON...BEFORE DIMINISHING AFTER
SUNSET.
SPECIFICS FOR KSTL...STILL HARD TO PIN DOWN EXACT COVERAGE AND
TIMING OF STORMS...LATEST HRRR MODEL INDICATING STORMS TO NOT MOVE
IN TIL AFTER 04Z TUESDAY...MAYBE EVEN LATER...BUT KEPT VCTS
MENTION AFTER 01Z TUESDAY FOR NOW AS WE COULD SEE STUFF FIRE UP
AHEAD OF MAIN ACTIVITY. STORMS TO TAPER OFF AFTER 07Z TUESDAY.
OTHERWISE...EXPECT VFR CIGS AND GUSTY SOUTH WINDS FOR THIS
AFTERNOON...BEFORE DIMINISHING AFTER SUNSET. ANOTHER ROUND OF
STORMS POSSIBLE AFTER 21Z TUESDAY...SO ADDED VCTS MENTION DURING
THIS PERIOD.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
112 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 112 PM CDT MON MAY 20 2013
TORNADO WATCH ISSUED FOR PORTIONS OF CENTRAL MO...SO UPDATED
ZONES/GRIDS FOR THIS. MORNING ACTIVITY FINALLY EXITING FAR
NORTHEAST PORTIONS OF FORECAST AREA. TIMING OF NEXT ROUND TO BE
LATER THIS AFTERNOON OVER CENTRAL MO AND CONTINUE INTO THIS
EVENING. WITH CLOUDS CLEARING OUT...TEMPERATURES ARE FINALLY
RECOVERING WITH HIGHS IN THE 80S...THOUGH UPPER 70S EXPECTED FAR
NORTH DUE TO EXITING STORMS/CLOUDS.
BYRD
&&
.SHORT TERM...(THROUGH TONIGHT)
ISSUED AT 358 AM CDT MON MAY 20 2013
MORNING CONVECTION WILL CONTINUE TO MOVE EWD THRU THE CWA EARLY
THIS MORNING. CURRENTLY DO NOT ANTICIPATE OUTFLOW FROM THIS
CONVECTION IMPACTING THE CWA LATER TODAY AS IT SHUD CONTINUE WELL
OUTSIDE OF THE CWA.
THE CDFNT CURRENTLY OVER ERN KS WILL MOVE EWD TODAY AND SHUD BE
JUST W OF THE CWA AROUND NOON. WITH THE ENTIRE AREA IN THE WARM
SECTOR...EXPECT AREA TO RECOVER WELL WITH AMPLE INSOLATION.
MDL SOLNS DIFFER REGARDING EXACTLY HOW TSRA WILL UNFOLD TODAY.
CONVECTION ALLOWING MDLS SUGGEST FOCUS WILL BE SW OF THE CWA THIS
AFTERNOON/EVE WITH THIS LINE MOVING NEWD INTO THE AREA LATE
TONIGHT. THE OPR MDLS SUGGEST TSRA WILL DEVELOP JUST AHEAD OF THE
CWA LATE THIS MORNING OR EARLY AFTERNOON. INTERESTINGLY...THE
LOCAL 4KM WRF PROVIDES A MERGER OF THESE TWO SOLNS...WHICH SEEMS
THE MOST LIKELY. WHILE TIMING REMAINS A QUESTION...WHAT DOES FORM
SHUD EVOLVE UPSCALE INTO A LINEAR MODE AS IT MOVES ACROSS THE
AREA. TSRA SHUD BE ON THE ERN EDGE OF THE CWA BY SUNRISE TUES.
LITTLE CHANGE WAS MADE TO TEMPS...KEEPING THE FORECAST AOA THE
WARMEST MOS.
TILLY
.LONG TERM...(MONDAY THROUGH NEXT SUNDAY)
ISSUED AT 331 PM CDT SUN MAY 19 2013
CURRENT INDICATIONS BASED ON THE DETERMINISTIC MODELS AND CONVECTION
ALLOWING MODELS IS THAT ANY THUNDERSTORMS REMAINING FROM THE OVERNIGHT
MCS SHOULD BE IN A DRASTICALLY WEAKENED STATE AT DAYBREAK. GIVEN THAT THE
PRIMARY SHORT WAVE TROF WILL HAVE ALREADY ROTATED NEWD INTO IOWA
AND A VEERED WSWLY LLJ...ANY REMAINING SHOWERS AND THUNDERSTORMS
WILL MOST LIKELY BE LOCATED FROM SOUTHWEST/SOUTH CENTRAL IL ACROSS
SE MO. THESE SHOULD DIMINISH BY MID MORNING AS LARGE SCALE SUBSIDENCE
OVERSPREADS THE REGION. IN THE WAKE OF THIS ACTIVITY AND GIVEN THE
TENDENCY TOWARDS CUMULIFORM CLOUDS...GOOD HEATING WILL COMMENCE.
THIS HEATING COMBINED WITH A MOIST BOUNDARY LAYER AND STEEP MID
LEVEL LAPSE RATES WILL CONTRIBUTE TO MODERATE-STRONG INSTABILITY
AND WEAK CONVECTIVE INHIBITION ACROSS THE ENTIRE AREA BY MID
AFTERNOON. SOUTHWESTERLY DEEP LAYER SHEAR AOA 40 KTS WOULD FAVOR
DISCRETE TO SEMI-DISCRETE SUPERCELLS AS THE DOMINATE STORM MODE
INITIALLY. AT THIS WE ARE EXPECTING A FAVORED WSW-ENE CORRIDOR
FOR STORM DEVELOPMENT AFTER 21Z FROM AROUND JEFFERSON CITY TO
BOWLING GREEN...ALTHO THIS AXIS COULD BE A BIT FURTHER SOUTH
DEPENDING ON ANY RESIDUAL BOUNDARIES. MERGERS AND ADDITIONAL
DEVELOPMENT WITHIN THIS ZONE AND UPSTREAM SHOULD RESULT IN A MIX
OF STORM MODES BY LATE AFTERNOON AND EVENING WITH POTENTIAL FOR
SUPERCELLS AND BOWING LINEAR SEGMENTS. THE OVERALL COVERAGE OF
STORMS SHOULD INCREASE DURING THE EVENING AS THE NEXT UPSTREAM
SHORT WAVE SPREADS LARGE SCALE ASCENT INTO THE REGION...ALSO
CONTRIBUTING TO UPSCALE STORM GROWTH. THERE EVENTUALLY COULD BE A
HEAVY RAIN THREAT FROM CENTRAL THROUGH EAST CENTRAL MO DUE TO
PERSISTENT AND TRAINING CONVECTION...BUT THE EXACT LOCATION IS TOO
DIFFICULT TO PINPOINT AT THIS POINT.
THE CONVECTIVE DETAILS BECOME LESS DEFINED ON TUESDAY DUE TO THE
POTENTIAL FOR RESIDUAL SHOWERS/STORMS FROM MONDAY NIGHT AND THE
PRESENCE OF MESOSCALE BOUNDARIES. THE OVERALL SYNOPTIC PATTERN
FEATURING THE UPPER TROF PROGRESSING EASTWARD WITH THE ATTENDANT
COLD FRONT MOVING THRU THE CWA DURING THE LATE AFTERNOON/EVENING
WOULD FAVOR HIGH THUNDERSTORM CHANCES...ESPECIALLY THE SE HALF OF
THE CWA. DEEP LAYER SHEAR OF 30-40 KTS AND WEAK-MODERATE INSTABILITY
WOULD CONTINUE TO FAVOR ORGANIZED-MIXED MODE SEVERE STORMS.
THE BOUNDARY FINALLY LOOKS TO PASS SOUTH OF THE AREA BY LATE
WEDNESDAY WITH ANOTHER REINFORCING BOUNDARY ON THURSDAY. THE PATTERN
THEN IS DOMINATED BY WEAK NW FLOW ON THE BACKSIDE OF THE UPPER TROF
AND LOOKS DRY THURSDAY NIGHT-SAT MORNING. THEREAFTER RETURN FLOW AND
WEAK DISTURBANCES PASSING THRU THE PLAINS UPPER RIDGE AND INTO THE
MID/UPPER MS VALLEY WILL BRING A RE-NEWED CHANCE OF
THUNDERSTORMS....ESPECIALLY THE NRN HALF OF THE CWA.
GLASS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 112 PM CDT MON MAY 20 2013
STILL HARD TO PIN DOWN EXACT COVERAGE AND TIMING OF STORMS...SO
KEPT VCTS MENTION AT KCOU THROUGH 03Z TUESDAY AND THROUGH 04Z
TUESDAY AT KUIN. FURTHER EAST OVER STL METRO AREA...HRRR MODEL
INDICATING STORMS TO NOT MOVE IN TIL AFTER 01Z TUESDAY...MAYBE
EVEN LATER...BUT KEPT VCTS MENTION AFTER 01Z TUESDAY FOR
NOW...TAPERING OFF AFTER 07Z TUESDAY. OTHERWISE...EXPECT VFR CIGS AND
GUSTY SOUTH WINDS FOR THIS AFTERNOON...BEFORE DIMINISHING AFTER
SUNSET.
SPECIFICS FOR KSTL...STILL HARD TO PIN DOWN EXACT COVERAGE AND
TIMING OF STORMS...LATEST HRRR MODEL INDICATING STORMS TO NOT MOVE
IN TIL AFTER 04Z TUESDAY...MAYBE EVEN LATER...BUT KEPT VCTS
MENTION AFTER 01Z TUESDAY FOR NOW AS WE COULD SEE STUFF FIRE UP
AHEAD OF MAIN ACTIVITY. STORMS TO TAPER OFF AFTER 07Z TUESDAY.
OTHERWISE...EXPECT VFR CIGS AND GUSTY SOUTH WINDS FOR THIS
AFTERNOON...BEFORE DIMINISHING AFTER SUNSET. ANOTHER ROUND OF
STORMS POSSIBLE AFTER 21Z TUESDAY...SO ADDED VCTS MENTION DURING
THIS PERIOD.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1227 PM CDT MON MAY 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 326 AM CDT MON MAY 20 2013
TODAY AND TONIGHT...
THE BAND OF SHOWERS AND RAIN ACROSS THE SOUTHWESTERN AND NORTHEAST
PORTIONS OF THE FCST AREA SHOULD EXIT SOUTH AND EAST BY
DAYLIGHT...MID MORNING AT THE LATEST. THE RAP...HRRR AND NAM THEN
DROP A SECOND BATCH OF RAIN AND SHOWERS SOUTH OUT OF WRN SD THIS
MORNING AND THIS AFTN. THIS AREA OF RAIN SHOULD PRESUMABLY CONTINUE
MOVING SOUTH THIS EVENING WITH A WEAKENING TREND.
THUNDERSTORM CHANCES ARE VERY LOW IF THE RAP AND NAM ARE CORRECT.
NEITHER INDICATE ANY ELEVATED INSTABILITY FROM 750 MB ON UP AND THE
SFC BASED NAM THUNDERSTORM PROBABILITY CHART IS 10 PERCENT OR LESS.
WINDS INCREASE TO WIND ADVISORY CRITERIA TODAY ACROSS PARTS OF THE
WEST WITH H850 WINDS INCREASING TO 45 KT. THE MET AND MAV GUIDANCE
WERE THE BASIS FOR THE FORECAST WIND SPEEDS WHICH INCREASE TO AROUND
30 MPH. WINDS SHOULD SLACKEN THIS EVENING AS LOW PRESSURE ACROSS THE
NRN PLAINS BEGINS TO FILL.
TEMPERATURES ARE A BLEND OF NAM...GEMREG AND ECM PLUS BIAS
CORRECTION FOR HIGHS AND THE 50S AND 60S TODAY WITH LOWS IN THE 40S
AND 50S TONIGHT.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 326 AM CDT MON MAY 20 2013
ON TUESDAY...
THE UPPER LOW IS FORECAST TO MOVE FROM CENTRAL INTO FAR SOUTHEAST
SOUTH DAKOTA. A LOBE ON THE WESTERN PERIPHERY OF THE LOW WILL
ROTATE THROUGH WESTERN NEBRASKA WITH A CHANCE FOR SHOWERS MAINLY
ACROSS NORTH CENTRAL NEBRASKA. DESPITE A MOIST PROFILE...LIFT WILL
BE VERY WEAK...MAINLY IN THE H850-H7 LAYER. HAVE LOWERED POPS TO
NEAR 50 PERCENT FOR SHERIDAN AND WRN CHERRY AND FROM 30-40 PERCENT
ACROSS THE REMAINDER OF NCTRL WITH SLIGHT CHANCE POPS IN SWRN NEBR
IN THE MORNING. REGARDING WINDS...STRONGEST WINDS FORECAST FROM
THE EASTERN PANHANDLE INTO SOUTHWEST NEBR...WHERE SUSTAINED WIND
WILL REACH NEAR 25KT AND GUST NEAR 35KT THROUGH THE DAY. THIS IS
DUE TO DEEP MIX DOWN POTENTIAL WHERE UNIDIRECTIONAL NORTHWEST
WINDS EXTEND FROM THE SFC TO ABOVE 400 MB. THEREFORE A WIND
ADVISORY MAY BE NEEDED IF FORECAST WINDS CONTINUE TO LOOK SIMILAR.
HIGHS WILL BE AFFECTED MOST BY CLOUD COVER/SHOWERS FROM 55-60
NCTRL TO NEAR 70 FAR SW.
TUESDAY NIGHT AND WEDNESDAY...
AS UPPER LOW MOVES SLOWLY EAST ACROSS NRN IOWA...STILL SUPPORTIVE
OF A FEW SHOWERS TUES NIGHT NORTH CENTRAL AND NORTHEAST WEDNESDAY
AS WRAPAROUND MOISTURE STILL PRESENT. AN UPPER RIDGE WILL ALSO
BUILD INTO THE CNTRL ROCKIES WEDNESDAY IN RESPONSE TO A
SUBSTANTIAL CLOSED LOW DIGGING INTO THE PAC NW. CLEARING SKIES IN
THE WEST AND WEAK HIGH PRESSURE BUILDING IN TO BRING COOLER LOWS
FROM THE UPPER 30S TO LOWER 40S WEST TO NEAR 45 EAST. ONLY A MINOR
CHANGE TO HIGHS WEDNESDAY FROM 62-66 NCTRL TO 67-73 SOUTH.
THURSDAY THROUGH SUNDAY...
AN UNSETTLED WEATHER PATTERN WILL SET UP AS AN UPPER TROUGH
REMAINS ACROSS THE WESTERN U.S AND A RIDGE ACROSS THE CENTRAL
CONUS. ABUNDANT LOW LEVEL MOISTURE WILL INCREASE WITH H85
DEWPOINTS FROM 12-15C AT TIMES FRIDAY THROUGH SUNDAY. THE PRESENCE
OF A NOCTURNAL LOW LEVEL JET WILL ALSO ALLOW FOR THUNDERSTORMS TO
POSSIBLY DEVELOP INTO AN MCS ACROSS THE REGION EACH NIGHT. HIGHS
FROM THE UPPER 60S TO LOWER 70S THU-FRI WILL WARM TO THE UPPER 70S
TO LOWER 80S SAT-SUN.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1227 PM CDT MON MAY 20 2013
AN UPPER LEVEL LOW WILL REMAIN NEARLY STATIONARY ACROSS SOUTH
DAKOTA... KEEPING LOW CEILINGS... SHOWERS... AND WIDESPREAD MVFR
CONDITIONS ACROSS NORTH CENTRAL NEBRASKA. FARTHER SOUTH... DRIER
AIR WILL KEEP CEILINGS ABOVE MVFR FOR THE MOST PART WITH SCATTERED
SHOWERS POSSIBLE. CONDITIONS SHOULD REMAIN SIMILAR THROUGH THE
NIGHT WITH PERHAPS CEILINGS LIFTING TO JUST ABOVE MVFR CRITERIA
ACROSS NORTH CENTRAL NEBRASKA... AS SOMEWHAT DRIER AIR BEGINS TO
FILTER INTO THE LOWER LEVELS OF THE ATMOSPHERE. SURFACE WINDS WILL
BE GUSTY THROUGH THE AFTERNOON AND DIMINISH SOMEWHAT TONIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 PM MDT THIS EVENING FOR NEZ004-022-023-035-
056>058.
&&
$$
SHORT TERM...CDC
LONG TERM...ROBERG
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1216 PM CDT MON MAY 20 2013
.UPDATE...
FORECAST IS GENERALLY ON TRACK FOR THIS AFTERNOON. SURFACE-BASED
CAPE VALUES ARE STILL EXPECTED INTO THE 500-1000 J/KG RANGE LATE
TODAY IN THE SOUTHEAST HALF OF THE CWA...ALONG WITH MODERATE
EFFECTIVE BULK SHEAR AROUND 40KT. A SURFACE TROUGH WAS NOTED IN
CENTRAL NEBRASKA...AND RAP FORECAST SUGGEST THIS WILL BE SWEEPING
ACROSS EASTERN NEBRASKA BEFORE 00Z. SO THE COMBINATION OF WEAK
INSTABILITY WITH MODERATE SHEAR AND A FOCUSING MECHANISM SHOULD
RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS DRIVEN BY AFTERNOON
HEATING. SMALL HAIL AND GUSTY WINDS ARE POSSIBLE GIVEN LAPSE RATES
APPROACHING 8C IN OUR FAR SOUTHEAST AND MODEST TEMP-DEW POINT
DEPRESSIONS.
DERGAN
&&
.AVIATION...18Z TAFS FOR KOFK...KLNK AND KOMA.
GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH TUESDAY MORNING.
SCATTERED TO BROKEN CUMULUS NEAR FL050 IS FORECAST THROUGH THE
AFTERNOON. A FEW SHOWERS OR ISOLATED THUNDERSTORMS COULD DEVELOP
BRINGING MVFR CONDITIONS TO SOME AREAS. HOWEVER CHANCES AT TAF
SITES ARE RATHER SLIM. PRECIPITATION SHOULD DISSIPATE WITH THE
SETTING SUN...THEN CIGS NEAR FL040 WILL OVERSPREAD EASTERN
NEBRASKA FROM THE NORTH. SOME MVFR CIGS ARE POSSIBLE IN NORTHEAST
NEBRASKA NEAR KOFK AFTER 06Z...BUT HAVE LEFT OUT OF TAF FORECAST
AT THE MOMENT.
DERGAN
&&
.PREV DISCUSSION... /ISSUED 323 AM CDT MON MAY 20 2013/
DISCUSSION...
THE UPPER LEVEL LOW CURRENTLY CENTERED OVER NE NEB AND ERN SD WILL
CONTINUE TO BE THE MAIN FORECAST ISSUE THROUGH THE SHORT TERM.
BROAD Q-G FORCING FOR ASCENT UNDER THE UPPER LEVEL LOW WAS
LEADING TO SCATTERED SHOWERS OVER CENTRAL AND NE NEB EARLY THIS
MORNING. THIS SHOULD CONT IN NE NEB WITH MOST OF THE CENTRAL AND
SOUTHERN CWA DRY THIS MORNING. SOME SUN IS EXPECTED TODAY OVER
THIS AREA OF THE CWA /SW IA AND SE NEB/ THAT WILL STEEPEN LOW
LEVEL LAPSE RATES. GIVEN THE RESIDUAL LOW LEVEL MOISTURE IN PLACE
ACROSS THIS AREA AND THE COLD MID LEVEL TEMPERATURES UNDER THE
UPPER LEVEL LOW...THE ATMOSPHERE SHOULD BECOME WEAKLY UNSTABLE
THIS AFTERNOON WITH AROUND 400-600 J/KG OF SBCAPE OVER THE CNTRL
AND SRN CWA. THIS SHOULD LEAD TO SCATTERED AFTERNOON SHOWERS AND
ISO THUNDERSTORMS ACROSS THE FA. SEVERE WEATHER GENERALLY SEEMS
UNLIKELY...BUT WITH THE STEEP MID LEVEL LAPSE RATES AND MODERATE
SHEAR SOME HAIL SEEMS POSSIBLE IF SUFFICIENT HEATING CAN TAKE
PLACE THROUGH THE MORNING. OTHERWISE THE SHOWERS AND ISO TSRA
SHOULD DIMINISH QUICKLY THIS EVENING WITH THE LOSS OF DAYTIME
HEATING. THE SETUP FOR TUESDAY ISN`T AS FAVORABLE FOR AFTERNOON
TSRA AS THE LOW LEVEL RESIDUAL MOISTURE GETS DISPLACED TO THE EAST
AS CAA MOVES THROUGH THE FA BEHIND A SFC CDFNT ON MON NIGHT. THIS
WILL LEAD TO SEASONABLY COOL TEMPERATURES FOR TUE/WED. WE MAY SEE
AN ISO SHOWER IN THE NRN FA UNDER THE UPPER LEVEL LOW...BUT THESE
WILL BE PRETTY ISOLATED.
THE LOW FINALLY STARTS TO SHIFT EAST ON THU WITH DRY WEATHER
RETURNING...BUT THIS WILL ONLY BE FOR A SHORT TIME AS LONGER RANGE
MODELS ARE FAIRLY CONSISTENT IN BRINGING IN A TROUGH TO THE
WESTERN US WITH WAA TYPE PRECIP DEVELOPING STARTING ON FRI AND
INTO NEXT WEEKEND. WITH THE RETURN FLOW TEMPERATURES WILL ALSO BE
RETURNING TO NEAR NORMAL AS WELL.
BOUSTEAD
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
232 PM EDT MON MAY 20 2013
.SYNOPSIS...
A FEW SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE TODAY AS A FRONTAL
BOUNDARY REMAINS NEAR OUR AREA. A BETTER THREAT FOR SHOWERS AND
THUNDERSTORMS WILL COME TUESDAY AND BEYOND AS A MORE SIGNIFICANT
FRONT AND LOW PRESSURE SYSTEM MOVE CLOSE TO OUR AREA. THE BIGGER
STORY WILL BE WARMER WEATHER WITH HIGH TEMPERATURES IN THE 70S TO
NEAR 80 THROUGH THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
UPDATED AT 1 PM... WEAK FRONTAL BOUNDARY IS CURRENTLY LOCATED
ACROSS FAR NORTHERN NEW YORK. SKIES HAVE BECOME PARTLY CLOUDY
SOUTH OF THE BOUNDARY ACROSS OUR AREA WITH SOME CONVECTIVE CLOUDS
DEVELOPING BUT NO INDICATIONS OF ANY DEEP CONVECTIVE DEVELOPMENT
THROUGH EARLY THIS AFTERNOON. LATEST RAP FORECASTS FOR THIS AFTERNOON
INDICATE INCREASING IN INSTABILITY WITH CAPE VALUES CLIMBING TO
800-1000 J/KG. HOWEVER SYNOPTIC-SCALE FORCING LOOKS WEAK WITH THE
FRONTAL BOUNDARY EXPECTED TO REMAIN TO THE NORTH. SOME HIGH
RESOLUTION MODELS SHOWING ISOLATED CONVECTIVE SHOWERS DEVELOPING
OVER CENTRAL NY LATER THIS AFTERNOON WITH COVERAGE LESS THAN 30
PERCENT. WEAK WIND FIELDS WOULD MEAN THAT ANY STORMS THAT DEVELOP
WILL BE OF THE PULSE VARIETY WITH ANY SEVERE THREAT LOW. WITH
CLEARING TEMPERATURES HAVE CLIMBED INTO THE 70S AND MANY PLACES
WILL REACH NEAR 80 THIS AFTERNOON.
1000 AM UPDATE...MADE MINOR CHANGES TO SHOW MORE OF A DRY FORECAST
ACROSS OUR AREA NOW AND FOR THE NEXT FEW HOURS AS THE CLOSEST AREA
OF SHOWERS OVER NNY WILL SAFELY PASS TO OUR NORTHEAST. STILL NOT
SEEING ANY BIG TRIGGERS FOR SHOWERS OR CONVECTION THIS AFTERNOON
SO SLIGHT CHANCE POPS SEEMS GREAT. THE HRRR DOES SHOW SOMETHING
CROSSING LAKE ERIE LATE IN THE DAY AND IT DOES MATCH UP NOW WITH A
DEVELOPING LINE OF CONVECTION OVER LOWER MICHIGAN SO WE WILL WATCH
THIS CLOSELY. IN ADDITION WHILE DRY NOW...VIS SATELLITE DOES SHOW
SOME MORE LUMPY OR CONVECTIVE LOOKING CUMULUS OVER THE FAR
NORTHEAST END OF LAKE ONTARIO SO THIS MAY TURN INTO SOMETHING IN
THE NEXT FEW HOURS. AGAIN NOT MUCH EXPECTED BUT ENOUGH AROUND TO
WARRANT AT LEAST A MENTION THIS PM. UNLIKE YESTERDAY SUNSHINE OVER
IS ALREADY OVER THE NORTHERN PART OF THE CWA AND WILL CONTINUE TO
PUSH SOUTH THROUGH MIDDAY. TEMPS LOOK ON TRACK TO REACH THE 70S.
THE PREVIOUS AFD IS BELOW...
4 AM UPDATE...
WK SFC LOW LOCATED ACRS SRN QUEBEC WL SLIDE OFF TO THE EAST TDA AS
UL WV PULLS EAST. AS IT DOES SO A WK SFC TROF WL APPCH NRN ZONES
THIS AFTN BFR IT WASHES OUT. AT THE SAME TIME A STRONG CLOSED LOW
ALOFT WL PINWHEEL ACRS THE NRN PLAINS FOR THE NEXT DAY OR TWO. THIS
LOW WHICH WAS RESPONSIBLE FOR YDA`S TORNADO OUTBREAK ACRS THE SRN
PLAINS IS ESSENTIALLY BLOCKED IN PLACE BY RIDGING TO THE EAST AND
WEST. LOW PROGGED TO BE STACKED THRU TUESDAY SWINGING A WMFNT THRU
THE AREA ON MON NGT.
FOR TDA, PATCHY FOG AND DRIZZLE CAN BE EXPECTED ACRS SRN ZONES AS
MARINE LYR RMNS THRU AT LEAST 12Z. AFT THIS TIME, WINDS BCM MORE
SWRLY LEADING TO SOME IMPROVEMENT IN LOW CLDS. WHILE LOW-LVL
MOISTURE WL RMN IN PLACE THIS AFTN, VRY LITTLE FRCG WL BE AVAILABLE
FOR ANY NOTICEABLE PCPN TDA AND WITH MODELS CONTG TO INDICATE
WIDESPREAD QPF ACRS THE AREA AND GIVEN THEIR PERFORMANCES THE LAST 2
DAYS, HV LWRD POPS OVR ENTIRE CWA TO ISOLD AT BEST. IS THE POTENTIAL
FOR AN ISOLD RUMBLE OR TWO OF THUNDER AND HV INCLUDED MENTION TWD
NOON UP NR BNDRY SLIPPING THRU AND OVRSPRDNG ENTIRE AREA THRU ABOUT
21Z. OF COURSE, LIMITATIONS EXIST STRICTLY FM EXTENSIVE CLD CVR
ALONG WITH WK FRCG BUT FEEL CHCS ARE NOT COMPLETELY NIL SO HV CONTD
ISOLD SHRA/TSRA CHC FOR THE AFTN.
FOR TONIGHT, WMFNT LIFTS THRU WITH OVRNGT LOWS EXPECTED TO RMN ARND
60F. DWPTS WL ONLY DROP INTO THE U50S. SKIES WL RANGE FM
PRTLY-MOCLDY DRG THE NIGHTTIME HRS WITH BNDRY IN VICINITY. SLGT CHC
POPS THRU MOST OF THE OVRNGT HRS THEN SLOWLY INCRSNG TWD DAWN FM THE
WEST AS ISENTROPIC LIFT INCREASES.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
4 AM UPDATE...
SW FLOW CONTS ON TUESDAY PER 00Z NAM AND ECMWF. MODELS PLACE CWA
SQUARELY IN THE WARM SECTOR DRG THE DAY. H5 RIDGE BEGINS TO WEAKEN
DRG THE AFTN AS PLAINS LOW BEGINS TO EJECT TO THE EAST. THIS WL
ALLOW WK S/WV TO IMPACT AREA DRG THE DAY, LEADING TO LKLY POPS AFT
18Z. AIRMASS WL LKLY DESTABILIZE IN WM SECTOR LEADING TO CAPES ARND
1000 J/KG BASED ON TEMPS IN THE LWR 80S AND DWPTS RISING INTO THE
MID-60S.
CHC FOR SHOWERS AND TSTMS CONTINUES THRU THE DAY ON WED AS WMFNT
RMNS TO OUR NORTH AND INSTABILITY GRADUALLY INCREASES. DUE TO
PROXIMITY OF BNDRY, SHOWERS APPEAR TO BE LKLY AT TIMES DRG THE DAY
ACRS CNTRL NY CNTYS WHILE ONLY SCTD THUNDER CAN BE EXPECTED, THUS HV
WORDED GRIDS AS LKLY SHOWERS AND CHANCE THUNDER.
MAV NUMBERS LOOK WAY TOO WARM FOR HIGHS ON WEDNESDAY DUE TO THE
GFS/S LACK OF CLD CVR. THINKING IS THAT MET NUMBERS WILL BE CLOSER
TO REALITY AND VLY LOCALES MAY HIT 80F BUT HILLTOPS WL RMN IN THE
U70S.
HV CONTD LKLY POPS WED NGT AS CD FNT APPCHS WRN NY AND H5 LOW EJECTS
INTO GREAT LKS, FLINGING WVS AT TIMES THRU THE PD. HV MADE VRY FEW
CHGS TO PRVS GRIDS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MEDIUM RANGE MODELS CONTINUE TO SHOW A DEEP UPPER LEVEL TROF OVER
THE NORTHEAST THROUGH MOST OF THE PERIOD WITH HEIGHTS GRADUALLY
BUILDING LATE AS THIS TROF LIFTS EAST. THIS WILL KEEP TEMPERATURES
5-10 DEGREES BELOW NORMAL WITH MIN TEMPS COLD ENOUGH FOR POSSIBLE
FROST BOTH FRIDAY/SATURDAY NIGHTS AND MAYBE EVEN SUNDAY NIGHT.
AT THE SFC, POST COLD FRONT SHOWERS/THUNDERSTORMS WILL LINGER
THROUGH THE OVERNIGHT PERIOD WITH BEST CHC FOR THUNDER DURING THE
EARLY EVENING. AS THE UPPER LEVEL TROF BUILDS IN ON FRIDAY THE CHC
FOR SHOWERS WILL CONTINUE WITH THE HIGHEST POPS IN THE SOUTHERN
CATSKILLS AND NE PA. REMAINDER OF PERIOD WILL BE DRY WITH PARTLY
TO MAINLY CLEAR CONDITIONS AS SFC HIGH PRES FROM CENTRAL CANADA
DROPS SOUTH ACROSS THE GREAT LAKES REGION TO OUR VCNTY BY MONDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
CONDITIONS ARE VFR ACROSS THE TERMINALS THIS AFTERNOON AND IN
GENERAL WILL REMAIN VFR THROUGH THIS TAF PERIOD. LATE TONIGHT, MVFR
CONDITIONS ARE POSSIBLE AT KELM DUE TO VALLEY FOG AND KAVP WITH
POSSIBLE MARINE LAYER.
THERE IS THE POTENTIAL FOR CONVECTION PRIMARILY TUESDAY AFTERNOON AS
WEAK BOUNDARY OVER NORTHERN NY MAY BECOME ACTIVE WITH DIURNAL
INSTABILITY. SHOWERS/THUNDERSTORMS ARE NOT INCLUDED IN THE TAFS
ATTM AS THE BEST CHANCE LOOKS AFTER 18Z BUT OVERALL A LOW
CONFIDENCE CONVECTIVE EVENT UNFOLDING TOMORROW AFTERNOON.
LIGHT AND VARIABLE WITH THROUGH TONIGHT BECOMING SOUTHWEST AT
5-10 KNOTS TUESDAY MORNING.
OUTLOOK...
WEDNESDAY/THURSDAY...MVFR POSSIBLE IN SHOWERS/THUNDERSTORMS.
FRIDAY/SATURDAY...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...PVN
NEAR TERM...MSE/PVN
SHORT TERM...HEDEN/PVN
LONG TERM...RRM
AVIATION...RRM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
125 PM EDT MON MAY 20 2013
.SYNOPSIS...
A FEW SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE TODAY AS A FRONTAL
BOUNDARY REMAINS NEAR OUR AREA. A BETTER THREAT FOR SHOWERS AND
THUNDERSTORMS WILL COME TUESDAY AND BEYOND AS A MORE SIGNIFICANT
FRONT AND LOW PRESSURE SYSTEM MOVE CLOSE TO OUR AREA. THE BIGGER
STORY WILL BE WARMER WEATHER WITH HIGH TEMPERATURES IN THE 70S TO
NEAR 80 THROUGH THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
UPDATED AT 1 PM... WEAK FRONTAL BOUNDARY IS CURRENTLY LOCATED
ACROSS FAR NORTHERN NEW YORK. SKIES HAVE BECOME PARTLY CLOUDY
SOUTH OF THE BOUNDARY ACROSS OUR AREA WITH SOME CONVECTIVE CLOUDS
DEVELOPING BUT NO INDICATIONS OF ANY DEEP CONVECTIVE DEVELOPMENT
THROUGH EARLY THIS AFTERNOON. LATEST RAP FORECASTS FOR THIS AFTERNOON
INDICATE INCREASING IN INSTABILITY WITH CAPE VALUES CLIMBING TO
800-1000 J/KG. HOWEVER SYNOPTIC-SCALE FORCING LOOKS WEAK WITH THE
FRONTAL BOUNDARY EXPECTED TO REMAIN TO THE NORTH. SOME HIGH
RESOLUTION MODELS SHOWING ISOLATED CONVECTIVE SHOWERS DEVELOPING
OVER CENTRAL NY LATER THIS AFTERNOON WITH COVERAGE LESS THAN 30
PERCENT. WEAK WIND FIELDS WOULD MEAN THAT ANY STORMS THAT DEVELOP
WILL BE OF THE PULSE VARIETY WITH ANY SEVERE THREAT LOW. WITH
CLEARING TEMPERATURES HAVE CLIMBED INTO THE 70S AND MANY PLACES
WILL REACH NEAR 80 THIS AFTERNOON.
1000 AM UPDATE...MADE MINOR CHANGES TO SHOW MORE OF A DRY FORECAST
ACROSS OUR AREA NOW AND FOR THE NEXT FEW HOURS AS THE CLOSEST AREA
OF SHOWERS OVER NNY WILL SAFELY PASS TO OUR NORTHEAST. STILL NOT
SEEING ANY BIG TRIGGERS FOR SHOWERS OR CONVECTION THIS AFTERNOON
SO SLIGHT CHANCE POPS SEEMS GREAT. THE HRRR DOES SHOW SOMETHING
CROSSING LAKE ERIE LATE IN THE DAY AND IT DOES MATCH UP NOW WITH A
DEVELOPING LINE OF CONVECTION OVER LOWER MICHIGAN SO WE WILL WATCH
THIS CLOSELY. IN ADDITION WHILE DRY NOW...VIS SATELLITE DOES SHOW
SOME MORE LUMPY OR CONVECTIVE LOOKING CUMULUS OVER THE FAR
NORTHEAST END OF LAKE ONTARIO SO THIS MAY TURN INTO SOMETHING IN
THE NEXT FEW HOURS. AGAIN NOT MUCH EXPECTED BUT ENOUGH AROUND TO
WARRANT AT LEAST A MENTION THIS PM. UNLIKE YESTERDAY SUNSHINE OVER
IS ALREADY OVER THE NORTHERN PART OF THE CWA AND WILL CONTINUE TO
PUSH SOUTH THROUGH MIDDAY. TEMPS LOOK ON TRACK TO REACH THE 70S.
THE PREVIOUS AFD IS BELOW...
4 AM UPDATE...
WK SFC LOW LOCATED ACRS SRN QUEBEC WL SLIDE OFF TO THE EAST TDA AS
UL WV PULLS EAST. AS IT DOES SO A WK SFC TROF WL APPCH NRN ZONES
THIS AFTN BFR IT WASHES OUT. AT THE SAME TIME A STRONG CLOSED LOW
ALOFT WL PINWHEEL ACRS THE NRN PLAINS FOR THE NEXT DAY OR TWO. THIS
LOW WHICH WAS RESPONSIBLE FOR YDA`S TORNADO OUTBREAK ACRS THE SRN
PLAINS IS ESSENTIALLY BLOCKED IN PLACE BY RIDGING TO THE EAST AND
WEST. LOW PROGGED TO BE STACKED THRU TUESDAY SWINGING A WMFNT THRU
THE AREA ON MON NGT.
FOR TDA, PATCHY FOG AND DRIZZLE CAN BE EXPECTED ACRS SRN ZONES AS
MARINE LYR RMNS THRU AT LEAST 12Z. AFT THIS TIME, WINDS BCM MORE
SWRLY LEADING TO SOME IMPROVEMENT IN LOW CLDS. WHILE LOW-LVL
MOISTURE WL RMN IN PLACE THIS AFTN, VRY LITTLE FRCG WL BE AVAILABLE
FOR ANY NOTICEABLE PCPN TDA AND WITH MODELS CONTG TO INDICATE
WIDESPREAD QPF ACRS THE AREA AND GIVEN THEIR PERFORMANCES THE LAST 2
DAYS, HV LWRD POPS OVR ENTIRE CWA TO ISOLD AT BEST. IS THE POTENTIAL
FOR AN ISOLD RUMBLE OR TWO OF THUNDER AND HV INCLUDED MENTION TWD
NOON UP NR BNDRY SLIPPING THRU AND OVRSPRDNG ENTIRE AREA THRU ABOUT
21Z. OF COURSE, LIMITATIONS EXIST STRICTLY FM EXTENSIVE CLD CVR
ALONG WITH WK FRCG BUT FEEL CHCS ARE NOT COMPLETELY NIL SO HV CONTD
ISOLD SHRA/TSRA CHC FOR THE AFTN.
FOR TONIGHT, WMFNT LIFTS THRU WITH OVRNGT LOWS EXPECTED TO RMN ARND
60F. DWPTS WL ONLY DROP INTO THE U50S. SKIES WL RANGE FM
PRTLY-MOCLDY DRG THE NIGHTTIME HRS WITH BNDRY IN VICINITY. SLGT CHC
POPS THRU MOST OF THE OVRNGT HRS THEN SLOWLY INCRSNG TWD DAWN FM THE
WEST AS ISENTROPIC LIFT INCREASES.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
4 AM UPDATE...
SW FLOW CONTS ON TUESDAY PER 00Z NAM AND ECMWF. MODELS PLACE CWA
SQUARELY IN THE WARM SECTOR DRG THE DAY. H5 RIDGE BEGINS TO WEAKEN
DRG THE AFTN AS PLAINS LOW BEGINS TO EJECT TO THE EAST. THIS WL
ALLOW WK S/WV TO IMPACT AREA DRG THE DAY, LEADING TO LKLY POPS AFT
18Z. AIRMASS WL LKLY DESTABILIZE IN WM SECTOR LEADING TO CAPES ARND
1000 J/KG BASED ON TEMPS IN THE LWR 80S AND DWPTS RISING INTO THE
MID-60S.
CHC FOR SHOWERS AND TSTMS CONTINUES THRU THE DAY ON WED AS WMFNT
RMNS TO OUR NORTH AND INSTABILITY GRADUALLY INCREASES. DUE TO
PROXIMITY OF BNDRY, SHOWERS APPEAR TO BE LKLY AT TIMES DRG THE DAY
ACRS CNTRL NY CNTYS WHILE ONLY SCTD THUNDER CAN BE EXPECTED, THUS HV
WORDED GRIDS AS LKLY SHOWERS AND CHANCE THUNDER.
MAV NUMBERS LOOK WAY TOO WARM FOR HIGHS ON WEDNESDAY DUE TO THE
GFS/S LACK OF CLD CVR. THINKING IS THAT MET NUMBERS WILL BE CLOSER
TO REALITY AND VLY LOCALES MAY HIT 80F BUT HILLTOPS WL RMN IN THE
U70S.
HV CONTD LKLY POPS WED NGT AS CD FNT APPCHS WRN NY AND H5 LOW EJECTS
INTO GREAT LKS, FLINGING WVS AT TIMES THRU THE PD. HV MADE VRY FEW
CHGS TO PRVS GRIDS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
445 AM UPDATE...
VERY LITTLE CHANGE FROM INHERITED FCST WITH STRONG COLD FRONT
STILL EXPECTED TO PASS THROUGH THE REGION ON THURSDAY. MODELS
CONTINUE TO ADVERTISE A FAIRLY DECENT COOL DOWN FOR THE UPCOMING
WEEKEND WITH THE LATEST ARRIVING 00Z ECMWF NOT AS COOL AS PREVIOUS
RUNS...WHICH IS NOW MORE IN LINE WITH THE GFS AND CANADIAN-CMC.
THAT SAID...STILL LOOKING FOR OVERNIGHT LOWS TO DIP DOWN INTO THE
MIDDLE TO UPPER 30S ACROSS FAVORED VALLEY LOCATIONS NEXT WEEKEND
WHICH WILL LIKELY LEAD TO FROST CONCERNS. UPCOMING WEEKEND STILL
LOOKING DRY AS STRONG HIGH PRESSURE NOSES SOUTH FROM SOUTHERN
CANADA.
PREVIOUS LONG TERM DISCUSSION... THE EXTENDED FORECAST WILL
FEATURE A DEEP UPPER LEVEL TROF OVER THE NORTHEAST KEEPING TEMPS
WELL BELOW NORMAL THROUGH THE PERIOD AFTER A COLD FRONTAL PASSAGE
ON THURSDAY.
AT THE SFC, A COLD FRONT WILL APPROACH THE REGION WEDNESDAY NIGHT
WITH FROPA ON THURSDAY. WILL CONTINUE WITH HIGH CHC/LIKELY POPS
THROUGH THIS PERIOD ALONG WITH THE CHC FOR THUNDERSTORMS. BUILDING
UPPER LEVEL TROF AND LINGERING POST FRONTAL MOISTURE WILL KEEP THE
THREAT FOR SHOWERS INTO FRIDAY. THE REMAINDER OF THE PERIOD WILL
BE DRY WITH PARTLY TO MAINLY CLEAR SKIES AS SFC HIGH PRES DROPS
SOUTH OVER THE AREA FROM CENTRAL CANADA. LOWS BOTH FRIDAY AND
SATURDAY NIGHT MAY BE COLD ENOUGH FOR FROST.
&&
.AVIATION /17Z MONDAY THROUGH FRIDAY/...
FAINT HINTS THROUGH OVERLYING CIRRUS THAT LINGERING MARINE LAYER
IS BEGINNING TO RETREAT AS WINDS BECOME MORE SOUTHERLY WITH TIME
THIS MORNING. IN FACT...SYR HAS ACTUALLY CLEARED OUT AND IS NOW
REPORTING VFR CONDITIONS. IN ANY EVENT...EXPECT THIS TREND TO
CONTINUE THIS MORNING AS WINDS CONTINUE TO VEER AND DAYTIME
HEATING COMMENCES. FOR NOW WE EXPECT IFR CONDITIONS TO LINGER AT
BGM FOR A FEW MORE HRS THROUGH ROUGHLY 14Z WITH IMPROVEMENTS
ANTICIPATED SHORTLY THEREAFTER. AT ELM AND ITH...IF IFR WERE TO
OCCUR THIS MORNING...IT WILL LIKELY ONLY BE BRIEF BEFORE THINGS
IMPROVE. BY LATE MORNING...ALL SITES SHOULD BE VFR WITH WEAK
SOUTHERLY WINDS OF 4-8 KTS PREVAILING REGION WIDE.
AS FOR SHWRS/STORMS...WEAK FRONTAL BOUNDARY NORTH OF THE FCST AREA
MAY SERVE AS A TRIGGER FOR DEVELOPING ACTIVITY. FOR NOW...BEST
POTENTIAL WILL BE FOR SYR AND RME HOWEVER WEAK WIND FIELD ALOFT
AND NO HINT OF ANY APPROACHING UPPER SUPPORT LEADS TO A FAIR AMOUNT
OF UNCERTAINTY AND THUS NO MENTION IN THE FCST AS OF NOW.
FOR TONIGHT...EXPECT POSSIBLE IFR CONDITIONS AFTER 06Z AT AVP IN
MOIST SOUTHWEST FLOW. FOR NOW...OVERALL CONFIDENCE OF RESTRICTIONS
AT REMAINING SITES REMAINS TOO LOW TO INCLUDE IN THE FCST DUE TO
MODEL/S SUGGESTION OF DRIER AIR OVER CENTRAL NY.
OUTLOOK...
TUESDAY/WEDNESDAY/THURSDAY...MVFR POSSIBLE IN SHOWERS/THUNDERSTORMS.
FRIDAY...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...PVN
NEAR TERM...MSE/PVN
SHORT TERM...HEDEN/PVN
LONG TERM...CMG
AVIATION...CMG
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
331 PM EDT MON MAY 20 2013
.SYNOPSIS...
A DISTURBANCE ALOFT MOVING ACROSS THE AREA WILL MAINTAIN SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER IS EXPECTED
MID WEEK. A COLD FRONT IS EXPECTED TO APPROACH AND CROSS THE REGION
ON FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER INTO THE NEXT
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 300 PM MONDAY...SPC MESOANALYSIS PAGE SHOWS THE HEAVIEST
CONVECTIVE RAINFALL IN ENCOMPASSED WITHIN A DEEP POCKET OF MOISTURE
STREWN ACROSS THE CENTRAL AND EASTERN CAROLINAS...WHERE PRECIPITABLE
WATERS WERE ESTIMATED AROUND 1.8 INCHES THIS AFTERNOON. WATER VAPOR
ANIMATIONS DEPICT A COMPLEX SET OF SWIRLS EMBEDDED WITHIN A WEAK
UPPER TROUGH FROM VIRGINIA TO NORTHERN FLORIDA. DIURNAL COOLING
INTO EVENING SHOULD REMOVE SOME INTENSITY OF CONVECTION...BUT GOOD
UPPER SUPPORT AND A MOISTURE RICH ENVIRONMENT SHOULD ALLOW FOR A
FEW BIG RAIN-MAKERS TO PERSIST THROUGH EVENING. THE OVERNIGHT
PERIOD WILL LIKELY SEE RE-DEVELOPMENT OVER THE WATERS AS LOW-LEVEL
BUOYANCY INCREASES. CIRCULATION AROUND BERMUDA HIGH PRESSURE WILL
HELP GUIDE OCEAN ACTIVITY ONTO THE COAST...AND THIS PROCESS MAY
LEAD TO NOTABLE RAIN AMOUNTS OF 1/2-1 INCH FOR THE COASTAL ZONES
OVERNIGHT. WITH THIS IN MIND WILL KEEP HIGH SCATTERED TO LIKELY
POP VALUES IN PLACE OVERNIGHT INTO DAYBREAK MONDAY...GRADUALLY
SHIFTING FOCUS INLAND...TO THE COAST IN THE NEAR TERM PERIOD.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...FORECAST MODELS ARE CONSISTENT IN SHOWING
THE MID LEVEL PATTERN TRANSITIONING FROM WHAT SEEMS LIKE A NEVER
ENDING TROUGH/WEAKNESS TO MORE OF A SOUTHWESTERLY FLOW. THIS IN
RESPONSE TO THE MASSIVE MID LEVEL LOW FINALLY OPENING UP ACROSS
THE NORTHERN PLAINS AND GETTING KICKED OUT.
AT THE SURFACE...BERMUDA HIGH PRESSURE WILL REMAIN THE MAIN PLAYER
ALTHOUGH THIS HAS LITTLE IMPACT OR CHANGE ON PREVAILING CONDITIONS
AS THIS HAS BEEN SECONDARY THE PAST FEW DAYS. POPS REMAIN ON A
DIURNAL CYCLE ALTHOUGH LOWER THROUGH THE PERIOD AS THE MID LEVEL
CATALYST IS ALL BUT REMOVED. HAVE OPTED FOR THE WARMER MAV NUMBERS
FOR TEMPERATURES THROUGH THE PERIOD.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 300 PM MONDAY...ONE LAST DAY OF WARM AND HUMID CONDITIONS ON
THURSDAY AS UPPER TROUGH AND SURFACE COLD FRONT BEAR DOWN ON THE
REGION FROM THE NW. SOMEWHAT SURPRISINGLY MODELS ARE GRAVITATING
TOWARDS A QUICKER SOLUTION AND THE FRONT MAY PUSH THROUGH TUESDAY
NIGHT. AHEAD OF IT SW FLOW AND HEIGHT FALLS SHOULD YIELD BETTER THAN
AVERAGE COVERAGE OF CONVECTION AND WITH A LARGELY PINNED SEABREEZE
THERE MAY BE NO PREFERRED LOCATION FOR MEASURABLE RAINFALL ESP THIS
FAR OUT IN TIME. SYSTEM WILL MOVE A LITTLE BIT SLOWLY OWING TO THE
STRENGTH OF THE DOWNSTREAM RIDGING AND RAIN CHANCES MAY LINGER INTO
FRIDAY ESPECIALLY ALONG THE COAST. MODEST COOLING AND STRONG DRYING
WILL THEN FOLLOW FOR THE WEEKEND AND SOME VERY COMFORTABLE AND
PLEASANT WEATHER APPEARS TO BE ON TAP. DAYTIME DEVIATIONS FROM CLIMO
TEMPS SHOULD BE RATHER SMALL BUT THE NIGHTS MAY TURN COOLISH DUE TO
THE DRYING. THE POST-FRONTAL HIGH MAY MOVE OFF THE COAST ON MONDAY
ALLOWING FOR AN UPTICK IN THE DEWPOINTS.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
AS OF 18Z...MORE SHOWERS/T-STORMS ARE EXPECTED THIS AFTN WITH
MVFR/TEMPO IFR CONDITIONS IN HEAVIER DOWNPOURS. HAVE INCLUDED
VCSH/VCTS AT ALL TERMS WITH TEMPO GROUPS ATTEMPTING TO CAPTURE THE
TIMING OF PCPN BASED ON RADAR TRENDS AND HRRR OUTPUT. VFR/MVFR
LIKELY WILL PREVAIL WITH SHORT PERIODS OF IFR VSBYS IN +SHRA. MOST
PCPN SHOULD BE NEARING THE COASTAL TERMS BY MID-AFTN...THOUGH MORE
SCT SHOWERS INLAND ARE POSSIBLE AS WELL. RAIN CHANCES RAPIDLY
DIMINISH AFTER 00Z TUESDAY. FOG/STRATUS COULD BE AN ISSUE OVERNIGHT
WITH TODAYS PERSISTENT RAINFALL...HIGHEST CONFIDENCE AT KLBT/KFLO.
EXPECT MOSTLY CLOUDY SKIES AGAIN ON TUESDAY WITH S-SW WINDS 6-10
KTS. HAVE INCLUDED VCSH ALONG THE COAST TMRW TO ACCOUNT FOR SLIGHT
PCPN CHANCES AS THE UPPER DISTURBANCE NEARS THE COAST.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 PM MONDAY...SUB-ADVISORY BUT LESS THAN IDEAL CONDITIONS
ON THE WATERS WITH SEAS MAINLY RUNNING 3-4 FT MOST AREAS EXCEPT
UP TO 5 FT VERY OUR WATERS OF NC. SEAS THROUGH DAYBREAK TUESDAY
WILL BE COMPRISED OF 3 FOOT SSE WAVES EVERY 6-7 SECONDS AND 1-2
FOOT ESE WAVES EVERY 10-11 SECONDS. MARINERS ARE ENCOURAGED TO
OBTAIN A RADAR BRIEFING BEFORE HEADING OUT AS SEVERAL TSTMS WILL
IMPACT THE 0-20NM COASTAL WATERS TONIGHT INTO TUESDAY MORNING.
AS FAR AS WINDS...WE CAN COUNT ON PERSISTENT SOUTHERLY FLOW OF
10-15 KT AS HIGH PRESSURE REMAINS ANCHORED OVER THE OFFSHORE
WATERS.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...BERMUDA HIGH PRESSURE REMAINS THE MAIN FEATURE
FOR THE COASTAL WATERS WITH A SOUTHERLY FLOW EXPECTED TO CONTINUE
THROUGH THE PERIOD. SPEEDS WILL CONTINUE IN A 10-15 KNOT RANGE
WITH A SLIGHT INCREASE CLOSER TO THE COAST EACH LATE MORNING AND
AFTERNOON WITH THE SEA BREEZE. THE LATEST RUN OF SWAN REMAINS
CONSISTENT WITH 2-4 FOOT SEAS.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 PM MONDAY...COAST WILL LIE BETWEEN STRONG HIGH PRESSURE
ACROSS THE WEST-CENTRAL ATLANTIC AND APPROACHING COLD FRONT TO THE
NW. THE LATTER WILL BE DISPLACED EASTWARD OF THE MORE TYPICAL
BERMUDA HIGH POSITION WHICH WILL ACT TO EASE THE GRADIENT OTHERWISE
EXPECTED GIVEN SUCH A LARGE ANTICYCLONE. THE RESULTING SWELL ENERGY
COULD BRING SOME SCEC-WORTHY 5 FT SEAS TO PART OF THE AREA MAINLY
NORTHERN ZONES. COLD FRONT NOW APPEARS FASTER THAN PREVIOUSLY
THOUGHT AND SHOULD YIELD VEERING WINDS BY FRIDAY MORNING WITH A TURN
TO OFFSHORE. THE OFFSHORE FETCH AND SWELL DISRUPTION WILL LEAD TO
LOWER SEAS ON FRIDAY BUT THEN THE ENSUING PUSH OF DRY HIGH PRESSURE
COULD TIGHTEN THE GRADIENT AGAIN TO WHERE HEADLINES TOUGH TO RULE
OUT.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...MJC
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
243 PM EDT MON MAY 20 2013
.SYNOPSIS...
A SHORTWAVE TROUGH WILL CONTINUE TO WORK THROUGH THE AREA THIS
AFTERNOON BRINGING UNSETTLED WEATHER THROUGH THIS EVENING. THE
TROUGH WILL MEANDER NORTHEASTWARD TUESDAY BEFORE MORE SETTLED
WEATHER RETURNS FOR WEDNESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 215 PM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
TODAY: WIDESPREAD SHOWERS AND THUNDERSTORMS HAVE BROKEN OUT IN A
SERIES OF LINES ACROSS THE CWA THIS AFTERNOON IN ASSOCIATION WITH A
SHORTWAVE IMPULSE PASSING THROUGH SOUTHERN VA. FOR THE MOST
PART...THUNDER HAS BEEN LIMITED TO A SELECT FEW CELLS WITH HEAVY
SHOWERS BEING THE PRIMARY MODE OF CONVECTION. THERE ARE SEVERAL WEAK
BOUNDARIES THAT HAVE SET UP THIS AFTERNOON. THE FIRST HAS LIFTED
NORTHEAST OF THE CWA...A SECOND ALONG THE HIGHWAY 1 CORRIDOR AND A
THIRD THROUGH THE TRIAD JUST EAST OF THE I-85 CORRIDOR. THESE TWO
LINES WILL GRADUALLY PUSH EASTWARD THIS AFTERNOON BRINGING MORE
HEAVY RAIN TO AN AREA ALREADY RECEIVING 2-3 INCHES OF RAIN IN SOME
LOCATIONS. THAT BEING SAID...RAIN RATES HAVE BEEN LOW ENOUGH AND
ENOUGH TIME HAS PASSED SINCE THE LAST RAINFALL THAT FLOODING SHOULD
NOT BE A WIDESPREAD PROBLEM THIS AFTERNOON. MORE LOCALIZED FLOODING
IS POSSIBLE WITH HEAVIER SHOWERS ESPECIALLY IN URBAN AREAS AND IN
THE NORMALLY FLASHY SMALLER CREEKS. RAINFALL TOTALS THIS AFTERNOON
WILL RANGE FROM A TENTH TO A QUARTER OF AN INCH OR SO WITH LOCALLY
HEAVIER AMOUNTS IN STRONGER STORMS. TRAINING OF STORMS SHOULD NOT BE
AS BIG OF A PROBLEM THIS AFTERNOON AND EVENING AS IT WAS EARLIER
THIS MORNING.
DESPITE THE SHORTWAVE ENERGY SEVERE POTENTIAL THIS AFTERNOON STILL
LOOKS EXTREMELY LIMITED. BOTH LOW AND MID-LEVEL LAPSE RATES ARE VERY
WEAK...AS IS THE EFFECTIVE SHEAR WHICH IS LESS THAN 15 KNOTS IN ALL
LOCATIONS. ML CAPE VALUES REMAIN BETWEEN 500-1000...LIMITED BY THE
CONTINUED BROKEN TO OVERCAST SKIES THIS AFTERNOON. THAT BEING SAID A
FEW CELL MERGERS HAVE ALLOWED SOME SHOWERS TO GROW TO A LEVEL
SUPPORTIVE OF VERY SMALL HAIL AND LIGHTNING. OTHERWISE HEAVY RAIN
AND MINOR FLOODING WILL CONTINUE TO BE THE MAIN THREAT OF THE DAY.
EXPECT WINDS THIS AFTERNOON TO GENERALLY BE SOUTHWESTERLY AT 5-10
KNOTS WITH THE OCCASIONAL GUST TO 15-20 KNOTS IN SHOWERS. HIGH
TEMPERATURES TODAY WILL MOST LIKELY VARY DEPENDING ON LOCATION WITH
A FEW BREAKS IN THE CLOUDS SUPPORTIVE OF HIGHS NEAR 80 WITH THOSE
LOCATIONS MAINTAINING OVERCAST SKIES TO TOP OUT IN THE MID TO UPPER
70S.
TONIGHT: HIGH RESOLUTION CONVECTIVE ALLOWING MODELS SUPPORT SHOWER
AND THUNDERSTORM ACTIVITY ENDING IN THE WEST AFTER 00Z AND
CONTINUING THROUGH 3Z IN THE EAST. THE ACCURACY OF THESE
MODELS...ESPECIALLY THE HRRR WAS BETTER EARLIER IN THE DAY THAN IT
IS NOW BUT THE SOLUTION STILL SEEMS REASONABLE GIVEN THE LOCATION OF
THE SHORTWAVE TO THE NORTH. AFTER CONVECTION ENDS EXPECT ISSUES WITH
FOG/LOW CEILINGS AND SUB-VFR VISIBILITIES AT ALL SITES OVERNIGHT.
THIS WILL CONTINUE THROUGH SUNRISE TUESDAY. LOWS WILL BE IN THE
LOWER TO MID 60S NW TO SE.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
AS OF 240 PM MONDAY...
FOR WEDNESDAY...WEAK SHORTWAVE RIDGING WILL BUILD OVER THE AREA...
WHILE AT THE SURFACE...THE BERMUDA HIGH WILL RIDGE WESTWARD INTO THE
CAROLINAS. ALL OF THIS WILL TRANSLATE TO AN EVEN FURTHER DECREASE IN
PRECIP COVERAGE. HOWEVER...SUFFICIENT MOISTURE WILL STILL BE IN
PLACE OVER THE REGION...WITH PWAT VALUES HOVERING NEAR 1.5 INCHES OR
SO. THEREFORE...AM STILL EXPECTING TO SEE WIDELY SCATTERED TO
SCATTERED DIURNALLY DRIVEN CONVECTION...WITH THE HIGHEST CHANCES
BEING ACROSS THE WESTERN PORTIONS OF THE FORECAST AREA. HIGHS ONCE
AGAIN SHOULD BE IN THE MID/UPPER 80S...WITH OVERNIGHT LOWS IN THE
MID/UPPER 60S.
SHOWER AND THUNDERSTORM COVERAGE SHOULD BEGIN TO INCREASE ONCE AGAIN
BY THE END OF THE WORK WEEK AS THE MID/UPPER LEVEL RIDGE SHIFTS
OFFSHORE AHEAD OF OUR NEXT MID/UPPER LEVEL TROUGH AND ASSOCIATED
COLD FRONT. MODELS REMAIN IN GENERAL AGREEMENT WITH BRINGING THE
FRONT THROUGH THE FORECAST AREA LATE THURSDAY NIGHT/EARLY FRIDAY.
THEREFORE...WILL SHOW POPS HIGHEST POPS CONCENTRATED DURING THE
THURSDAY/EARLY FRIDAY TIME FRAME...THEN DECREASING FROM WEST TO EAST
THROUGHOUT THE DAY ON FRIDAY. BULK SHEAR VALUES WILL INCREASE TO
AROUND 25 KNOTS OR SO...THEREFORE BETTER STORM ORGANIZATION IS
EXPECTED...HOWEVER THE BEST UPPER LEVEL FORCING WILL PASS WELL TO
OUR NORTH. THEREFORE...EVEN THOUGH AN ISOLATED SEVERE STORM CANNOT
BE COMPLETELY RULED OUT...THE OVERALL THREAT REMAINS LOW AT THIS
TIME. WITH THE INCREASED PRECIP CHANCES/CLOUDS ON THURSDAY AND
FRIDAY...TEMPS WILL MOSTLY BE IN THE LOW/MID 80S.
IT STILL APPEARS THE WEEKEND AND INTO EARLY NEXT WEEK WILL BE DRY AS
HIGH PRESSURE BUILDS IN BEHIND THE DEPARTING FRONT. SLIGHTLY COOLER
TEMPS ARE EXPECTED DURING THIS TIME FRAME...GENERALLY THE UPPER 70S
TO LOWER 80S...WITH OVERNIGHT LOWS IN THE 50S.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 115 PM MONDAY...
24 HOUR TAF PERIOD:
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL PREVAIL THIS
AFTERNOON ACROSS THE CWA AT ALL TERMINALS. CURRENTLY RADAR SHOWS
SHORTWAVE CURRENTLY MOVING ACROSS THE TRIAD WITH STRONGER CELLS ON
THE EASTERN SIDE WITH LINGERING SHOWERS TO THE WEST. FOR THE TRIAD
STRONGEST SHOWERS AND THUNDERSTORMS MOST LIKELY MOVING THROUGH NOW
THROUGH THE NEXT COUPLE OF HOURS AND DOWN TRENDING TO MOSTLY LIGHT
SHOWERS THEREAFTER. FURTHER TO THE EAST CONDITIONS SHOULD REMAIN
MORE FAVORABLE FOR HEAVIER SHOWERS AND THUNDERSTORMS THROUGH EARLY
EVENING. EXPECT CEILINGS TO BOUNCE BETWEEN VFR AND MVFR AND SINKING
OCCASIONALLY TO IFR IN THE STRONGER CELLS. WILL COVER THIS WITH A
TEMPO GROUP IN THE TAFS WITH VFR/MVFR PREVAILING. WINDS WILL REMAIN
GENERALLY SOUTHWESTERLY AT 5-10 KNOTS WITH OCCASIONAL GUSTS OF 15-20
IN HEAVY SHOWERS.
AFTER PRECIPITATION WINDS DOWN TONIGHT EXPECT SOME LOW
CEILINGS/VISIBILITIES...GENERALLY AFTER 3Z. EXPECT SOME FOG IN THE
WEST WITH MORE OF A LOW STRATUS SITUATION FURTHER TO THE EAST.
CONDITIONS SHOULD REMAIN SUB VFR EVERYWHERE UNTIL 15Z WHEN VFR
CEILINGS AND VISIBILITIES SHOULD RETURN. ALTHOUGH CONDITIONS WILL BE
IMPROVING AND GENERALLY DRYING...THE MESO-LOW WILL LINGER OVERHEAD
KEEPING THE CHANCE FOR SHOWERS ALIVE THROUGH THE END OF THE TAF
PERIOD.
LONG TERM:
LOW STRATUS AND FOG ARE EXPECTED TO RETURN TUESDAY NIGHT INTO
WEDNESDAY. WEDNESDAY WILL BE THE DRIEST DAY BUT WILL STILL HAVE THE
CHANCE FOR DIURNAL SHOWERS AND STORMS. THURSDAY AND THURSDAY NIGHT
WILL FEATURE THE PASSAGE OF A COLD FRONT AND A RETURN TO SUB-VFR
CONDITIONS. VFR CONDITIONS WILL GRADUALLY RETURN TO THE AREA ON
FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...ELLIS
SHORT TERM...ELLIS
LONG TERM...KRR
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
221 PM EDT MON MAY 20 2013
.SYNOPSIS...
A SHORTWAVE TROUGH WILL CONTINUE TO WORK THROUGH THE AREA THIS
AFTERNOON BRINGING UNSETTLED WEATHER THROUGH THIS EVENING. THE
TROUGH WILL MEANDER NORTHEASTWARD TUESDAY BEFORE MORE SETTLED
WEATHER RETURNS FOR WEDNESDAY.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 215 PM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
TODAY: WIDESPREAD SHOWERS AND THUNDERSTORMS HAVE BROKEN OUT IN A
SERIES OF LINES ACROSS THE CWA THIS AFTERNOON IN ASSOCIATION WITH A
SHORTWAVE IMPULSE PASSING THROUGH SOUTHERN VA. FOR THE MOST
PART...THUNDER HAS BEEN LIMITED TO A SELECT FEW CELLS WITH HEAVY
SHOWERS BEING THE PRIMARY MODE OF CONVECTION. THERE ARE SEVERAL WEAK
BOUNDARIES THAT HAVE SET UP THIS AFTERNOON. THE FIRST HAS LIFTED
NORTHEAST OF THE CWA...A SECOND ALONG THE HIGHWAY 1 CORRIDOR AND A
THIRD THROUGH THE TRIAD JUST EAST OF THE I-85 CORRIDOR. THESE TWO
LINES WILL GRADUALLY PUSH EASTWARD THIS AFTERNOON BRINGING MORE
HEAVY RAIN TO AN AREA ALREADY RECEIVING 2-3 INCHES OF RAIN IN SOME
LOCATIONS. THAT BEING SAID...RAIN RATES HAVE BEEN LOW ENOUGH AND
ENOUGH TIME HAS PASSED SINCE THE LAST RAINFALL THAT FLOODING SHOULD
NOT BE A WIDESPREAD PROBLEM THIS AFTERNOON. MORE LOCALIZED FLOODING
IS POSSIBLE WITH HEAVIER SHOWERS ESPECIALLY IN URBAN AREAS AND IN
THE NORMALLY FLASHY SMALLER CREEKS. RAINFALL TOTALS THIS AFTERNOON
WILL RANGE FROM A TENTH TO A QUARTER OF AN INCH OR SO WITH LOCALLY
HEAVIER AMOUNTS IN STRONGER STORMS. TRAINING OF STORMS SHOULD NOT BE
AS BIG OF A PROBLEM THIS AFTERNOON AND EVENING AS IT WAS EARLIER
THIS MORNING.
DESPITE THE SHORTWAVE ENERGY SEVERE POTENTIAL THIS AFTERNOON STILL
LOOKS EXTREMELY LIMITED. BOTH LOW AND MID-LEVEL LAPSE RATES ARE VERY
WEAK...AS IS THE EFFECTIVE SHEAR WHICH IS LESS THAN 15 KNOTS IN ALL
LOCATIONS. ML CAPE VALUES REMAIN BETWEEN 500-1000...LIMITED BY THE
CONTINUED BROKEN TO OVERCAST SKIES THIS AFTERNOON. THAT BEING SAID A
FEW CELL MERGERS HAVE ALLOWED SOME SHOWERS TO GROW TO A LEVEL
SUPPORTIVE OF VERY SMALL HAIL AND LIGHTNING. OTHERWISE HEAVY RAIN
AND MINOR FLOODING WILL CONTINUE TO BE THE MAIN THREAT OF THE DAY.
EXPECT WINDS THIS AFTERNOON TO GENERALLY BE SOUTHWESTERLY AT 5-10
KNOTS WITH THE OCCASIONAL GUST TO 15-20 KNOTS IN SHOWERS. HIGH
TEMPERATURES TODAY WILL MOST LIKELY VARY DEPENDING ON LOCATION WITH
A FEW BREAKS IN THE CLOUDS SUPPORTIVE OF HIGHS NEAR 80 WITH THOSE
LOCATIONS MAINTAINING OVERCAST SKIES TO TOP OUT IN THE MID TO UPPER
70S.
TONIGHT: HIGH RESOLUTION CONVECTIVE ALLOWING MODELS SUPPORT SHOWER
AND THUNDERSTORM ACTIVITY ENDING IN THE WEST AFTER 00Z AND
CONTINUING THROUGH 3Z IN THE EAST. THE ACCURACY OF THESE
MODELS...ESPECIALLY THE HRRR WAS BETTER EARLIER IN THE DAY THAN IT
IS NOW BUT THE SOLUTION STILL SEEMS REASONABLE GIVEN THE LOCATION OF
THE SHORTWAVE TO THE NORTH. AFTER CONVECTION ENDS EXPECT ISSUES WITH
FOG/LOW CEILINGS AND SUB-VFR VISIBILITIES AT ALL SITES OVERNIGHT.
THIS WILL CONTINUE THROUGH SUNRISE TUESDAY. LOWS WILL BE IN THE
LOWER TO MID 60S NW TO SE.
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 215 PM MONDAY...
TUESDAY STILL SHOWS THE UPPER LEVEL TROUGH LINGERING AT LEAST OVER
THE NORTHEASTERN PART OF THE STATE WITH A SURFACE HIGH OVER THE
SOUTHWESTERN ATLANTIC. THE BEST MOISTURE TRANSPORT AND PRECIPITABLE
WATER VALUES WILL SHIFT TO THE EASTERN HALF OF THE STATE TOMORROW
BUT WILL STILL HAVE THE CHANCE FOR SHOWERS AND THUNDERSTORMS TO
DEVELOP WITH DIURNAL HEATING. ONCE AGAIN THE SEVERE THREAT WILL BE
SEVERELY HINDERED BY LACK OF GOOD LAPSE RATES...SHEAR...AND
INSTABILITY IN THE MOISTURE CONVERGENCE ZONE. THE BEST INSTABILITY
WILL BE ACROSS THE TRIAD...WHERE CLOUD COVER SHOULD BE
DECREASED...BUT ALSO WHERE THE LOW LEVELS WILL BE A BIT DRIER. IF WE
CAN GET A STORM TO FORM...THE BEST CHANCE FOR SEVERE STORMS WOULD BE
BACK ACROSS THE NORTHWEST LATE TOMORROW AFTERNOON WITH DAMAGING
WINDS THE PRIMARY THREAT...BUT ONCE AGAIN THIS IS A VERY SMALL
THREAT AND NOT EXPECTING THIS TO HAPPEN AT THIS TIME.
MODELS HAVE COME INTO A BIT BETTER AGREEMENT ON TEMPERATURES FOR
TOMORROW WITH HIGHS IN THE MID 80S EXPECTED ACROSS THE CWA AND
PERHAPS A FEW DEGREES WARMER IN THE TRIAD WHERE THERE WILL BE
GREATER INSOLATION.
TUESDAY NIGHT THINGS WILL BEGIN TO DRY OUT AS THE MESO LOW PUSHES
OFF TO THE NORTHEAST AND WEAK UPPER LEVEL RIDGING TAKES OVER.
SURFACE DEWPOINTS WILL REMAIN IN THE LOWER TO MID 60S AND LOW FOG
AND/OR STRATUS COULD ONCE AGAIN BE A PROBLEM TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT LOWS IN THE MIDDLE 60S TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 AM MONDAY...
UPPER LEVEL RIDGE BUILDS BRIEFLY OVER THE AREA ON WEDNESDAY... WHICH
SHOULD DIMINISH THE COVERAGE OF CONVECTION... ALTHOUGH DIURNALLY
DRIVEN THUNDERSTORMS CONTINUE TO BE POSSIBLE WITH THE MOIST AIRMASS
OVER THE AREA. PWATS WILL REMAIN NEAR 1.5... 2 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR. WITH WEAK SHEAR... EXPECTING
PULSE TYPE STORMS. HIGHS IN THE MID 80S... LOWS MID 60S.
UPPER LEVEL RIDGE SHIFTS OFFSHORE THURSDAY. AFTERNOON THUNDERSTORMS
CONTINUE TO BE POSSIBLE IN THE AFTERNOON THURSDAY AS PWATS REMAIN
ABOVE NORMAL. BULK SHEAR INCREASES TO 25 TO 30 KTS... WHICH MAY
SUPPORT SOME MULTICELL ORGANIZATION. THICKNESSES REMAIN NEAR TO
SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY... FAVORING TEMPERATURES
CONTINUING TO A BE A FEW DEGREES ABOVE NORMAL... WITH HIGHS IN THE
80S AND LOWS IN THE UPPER 60S. THE TROUGH OVER THE MIDWEST MOVES
EASTWARD ON THURSDAY... AND THE ATTENDANT COLD FRONT PUSHES ACROSS
THE REGION FRIDAY. TIMING HAS TRENDED FASTER DURING TODAYS MODEL
RUNS... WITH THE FRONT MAKING IT THROUGH THE AREA EARLY FRIDAY...
AND TO THE CAROLINA COAST FRIDAY MORNING. STRONGEST DYNAMIC FORCING
REMAINS NORTH OVER NEW ENGLAND... AND WITH THE TIMING NOW LOOKING
MORE DIURNALLY UNFAVORABLE... DO NOT EXPECT A THREAT OF SEVERE
WEATHER.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 115 PM MONDAY...
24 HOUR TAF PERIOD:
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL PREVAIL THIS
AFTERNOON ACROSS THE CWA AT ALL TERMINALS. CURRENTLY RADAR SHOWS
SHORTWAVE CURRENTLY MOVING ACROSS THE TRIAD WITH STRONGER CELLS ON
THE EASTERN SIDE WITH LINGERING SHOWERS TO THE WEST. FOR THE TRIAD
STRONGEST SHOWERS AND THUNDERSTORMS MOST LIKELY MOVING THROUGH NOW
THROUGH THE NEXT COUPLE OF HOURS AND DOWN TRENDING TO MOSTLY LIGHT
SHOWERS THEREAFTER. FURTHER TO THE EAST CONDITIONS SHOULD REMAIN
MORE FAVORABLE FOR HEAVIER SHOWERS AND THUNDERSTORMS THROUGH EARLY
EVENING. EXPECT CEILINGS TO BOUNCE BETWEEN VFR AND MVFR AND SINKING
OCCASIONALLY TO IFR IN THE STRONGER CELLS. WILL COVER THIS WITH A
TEMPO GROUP IN THE TAFS WITH VFR/MVFR PREVAILING. WINDS WILL REMAIN
GENERALLY SOUTHWESTERLY AT 5-10 KNOTS WITH OCCASIONAL GUSTS OF 15-20
IN HEAVY SHOWERS.
AFTER PRECIPITATION WINDS DOWN TONIGHT EXPECT SOME LOW
CEILINGS/VISIBILITIES...GENERALLY AFTER 3Z. EXPECT SOME FOG IN THE
WEST WITH MORE OF A LOW STRATUS SITUATION FURTHER TO THE EAST.
CONDITIONS SHOULD REMAIN SUB VFR EVERYWHERE UNTIL 15Z WHEN VFR
CEILINGS AND VISIBILITIES SHOULD RETURN. ALTHOUGH CONDITIONS WILL BE
IMPROVING AND GENERALLY DRYING...THE MESO-LOW WILL LINGER OVERHEAD
KEEPING THE CHANCE FOR SHOWERS ALIVE THROUGH THE END OF THE TAF
PERIOD.
LONG TERM:
LOW STRATUS AND FOG ARE EXPECTED TO RETURN TUESDAY NIGHT INTO
WEDNESDAY. WEDNESDAY WILL BE THE DRIEST DAY BUT WILL STILL HAVE THE
CHANCE FOR DIURNAL SHOWERS AND STORMS. THURSDAY AND THURSDAY NIGHT
WILL FEATURE THE PASSAGE OF A COLD FRONT AND A RETURN TO SUB-VFR
CONDITIONS. VFR CONDITIONS WILL GRADUALLY RETURN TO THE AREA ON
FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ELLIS
NEAR TERM...ELLIS
SHORT TERM...ELLIS
LONG TERM...SEC
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
122 PM EDT MON MAY 20 2013
.SYNOPSIS...
A DISTURBANCE ALOFT MOVING ACROSS THE AREA WILL MAINTAIN SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. DRIER AND WARMER WEATHER IS EXPECTED
MID WEEK. A COLD FRONT IS EXPECTED TO APPROACH AND CROSS THE REGION
ON FRIDAY...BRINGING DRIER AND SLIGHTLY COOLER WEATHER INTO THE NEXT
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1037 AM MONDAY...LATEST RADAR TRENDS SHOW THE AXIS OF HEAVIEST
RAINFALL INLAND IS SHIFTING EAST AND AWAY FROM AREAS THAT HAVE
RECEIVED PLENTIFUL TO EXCESSIVE RAINFALL. THIS EASTWARD PROGRESS WILL
HELP ALLEVIATE THE NEAR TERM FLOODING POTENTIAL...AND CURRENTLY NO
FLOOD WARNING OR ADVISORY PRODUCTS ARE IN EFFECT. THE FLOOD WARNING
FOR MARLBORO COUNTY LAST NIGHT AND THIS MORNING HAD VERIFICATION
WITH FLOODING OF MAIN ST IN BENNETTSVILLE WHERE EARLIER...WATER HAD
RISEN UPON THE ADJACENT SIDEWALKS. CURRENT ACTIVITY WILL WANE OVER
THE WATERS AS LOW-LEVEL BUOYANCY WEAKENS. THE AFTERNOON FOCUS WILL
BE IN FOLLOWING THE TRENDS OF THE MAIN AXIS OF RAINFALL INLAND
EDGING SLOWLY TOWARD THE COAST. OUR CENTRAL AND EVENTUALLY THE
EASTERN ZONES STAND TO RECEIVE AN INCH OR MORE OF RAIN AS THE SLOW
EAST COMPONENT OF THE STEERING FLOW PREVAILS. PORTIONS OF THE
PREVIOUS DISCUSSION FOLLOWS.
A WEAK UPPER LEVEL DISTURBANCE WILL ELONGATE NORTH-TO-SOUTH TODAY
ACROSS THE CENTRAL CAROLINAS...EVENTUALLY CLEAVING INTO TWO
INDIVIDUAL PIECES TONIGHT. CYCLONIC FLOW SURROUNDING THIS FEATURE
ALOFT IS VERY WEAK AND STORM CELL MOTION IS ANTICIPATED TO BE SLOW
TODAY. WITH PRECIPITABLE WATER VALUES NOW IN THE SUMMER/TROPICAL
RANGE OF 1.6 TO 1.8 INCHES AND MODEL FORECAST SOUNDINGS SHOWING
ALMOST 10000 FEET OF WARM CONVECTIVE CLOUD DEPTH (LCL AROUND 2500 FT
VERSUS AN ENVIRONMENTAL FREEZING LEVEL OF 12500 FT) THERE IS A
GROWING POTENTIAL FOR HEAVY RAINFALL...PERHAPS EVEN EXCESSIVE
RAINFALL AND FLOODING LATER TODAY. I DO NOT PLAN TO ISSUE A FLOOD
WATCH...BUT WILL INCLUDE HEAVY RAIN MENTION IN THE FORECAST GRIDS
AND HAZARDOUS WX OUTLOOK.
A STABILIZING BOUNDARY LAYER AND A WEAKENING UPPER LEVEL DISTURBANCE
TONIGHT SHOULD PRODUCE A RAPID DECREASE IN COVERAGE OF SHOWERS.
SOUTH WINDS MAY STILL ADVECT NOCTURNAL MARINE CONVECTION ONSHORE SO
THE HIGHEST POPS (30-40 PERCENT) WILL REMAIN OVERNIGHT NEAR THE
BEACHES...WITH LESSER CHANCES INLAND. LOWS SHOULD FALL TO 66-69 FOR
MOST AREAS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...HIGH PRESSURE OFFSHORE WILL CONTINUE ITS
INFLUENCE ACROSS THE CAROLINAS...BUT A DECREASING TREND IN
CONVECTION WITH WARMING TEMPS IS EXPECTED THROUGH THE SHORT TERM.
BUILDING 1000-500MB THICKNESSES AND SOME WEAK NVA BEHIND A DEPARTING
SHORTWAVE WILL CREATE SUBSIDENCE WITH INCREASED DRYING THROUGH THE
COLUMN. FORECAST PROFILES SUGGEST SIGNIFICANT DRY AIR ABOVE
800MB...AND THIS IS ECHOED IN PWATS FALLING TO 1.25 INCHES BY
WEDNESDAY. THIS WILL TEND TO INHIBIT MUCH IN THE WAY OF
CONVECTION...BUT WITH TEMPS RISING WELL INTO THE 80S...ISOLATED
CONVECTION WILL REMAIN POSSIBLE...ESPECIALLY TUESDAY. WILL CONTINUE
LOW-CHC POP TUESDAY AND SCHC WEDNESDAY...BUT WOULD NOT BE SURPRISED
IF WED ENDS UP BEING DRY ACROSS THE CWA.
TEMPS WILL RESPOND TO BULGING HEIGHTS...RISING FROM THE LOW/MID 80S
TUESDAY INTO THE MID/UPR 80S WEDNESDAY. LOWS WILL REMAIN WELL ABOVE
NORMAL FOR MID-MAY THANKS TO CONTINUED SOUTHERLY WINDS...FALLING
ONLY INTO THE UPPER 60S BOTH NIGHTS.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...PATTERN CHANGE TO OCCUR DURING THE EXTENDED AS
COLD FRONT CROSSES THE AREA FRIDAY...USHERING IN A MUCH DRIER
AIRMASS TO THE CAROLINAS.
BERMUDA HIGH AND MID LEVEL RIDGING WILL PERSIST AT THE START OF THE
PERIOD...BUT FULL LATITUDE TROUGH WILL BEGIN TO DISPLACE THE RIDGE
CAUSING INCREASED CONVECTIVE CHANCES AND SLIGHTLY COOLER TEMPS. GFS
HAS SPED UP TIMING OF FRONT CONSIDERABLY...WHICH DOESN`T MAKE A LOT
OF SENSE BASED OFF RESTRICTIVE ANTECEDENT FLOW OF THE UPPER
PATTERN...AND FAVOR THE SLOWER CMC/ECMWF WHICH HAS THE FROPA
OCCURRING FRIDAY AFTN. THIS WILL SUPPORT ANOTHER DAY OF CONVECTION
AHEAD OF THE FRONT...BUT DRYING WILL OCCUR RAPIDLY BEHIND IT AS HIGH
PRESSURE BUILDS IN FROM THE NW. WHILE OVERALL TEMPERATURE CHANGE
WILL BE MINIMAL...WITH TEMPS ONLY A FEW DEGREES COOLER DURING THE
WKND...IT WILL BE MUCH DRIER...AND A BEAUTIFUL WKND APPEARS TO BE IN
STORE FOR THE AREA WITH TEMPS SLIGHTLY BELOW CLIMO.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AS OF 18Z...MORE SHOWERS/T-STORMS ARE EXPECTED THIS AFTN WITH
MVFR/TEMPO IFR CONDITIONS IN HEAVIER DOWNPOURS. HAVE INCLUDED
VCSH/VCTS AT ALL TERMS WITH TEMPO GROUPS ATTEMPTING TO CAPTURE THE
TIMING OF PCPN BASED ON RADAR TRENDS AND HRRR OUTPUT. VFR/MVFR
LIKELY WILL PREVAIL WITH SHORT PERIODS OF IFR VSBYS IN +SHRA. MOST
PCPN SHOULD BE NEARING THE COASTAL TERMS BY MID-AFTN...THOUGH MORE
SCT SHOWERS INLAND ARE POSSIBLE AS WELL. RAIN CHANCES RAPIDLY
DIMINISH AFTER 00Z TUESDAY. FOG/STRATUS COULD BE AN ISSUE OVERNIGHT
WITH TODAYS PERSISTENT RAINFALL...HIGHEST CONFIDENCE AT KLBT/KFLO.
EXPECT MOSTLY CLOUDY SKIES AGAIN ON TUESDAY WITH S-SW WINDS 6-10
KTS. HAVE INCLUDED VCSH ALONG THE COAST TMRW TO ACCOUNT FOR SLIGHT
PCPN CHANCES AS THE UPPER DISTURBANCE NEARS THE COAST.
EXTENDED OUTLOOK...SCATTERED SHOWERS/TSTMS WITH TEMPO MVFR ON
TUESDAY. CHANCE OF SHOWERS THURSDAY THROUGH EARLY FRIDAY. OTHERWISE
VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1037 AM MONDAY...THE OVERALL PATTERN WILL BE LITTLE CHANGED
FROM YESTERDAY WITH SURFACE HIGH PRESSURE REMAINING ANCHORED ALMOST
1000 MILES EAST OF CAPE HATTERAS AND LOW PRESSURE MOVING SLOWLY
ACROSS THE NORTHERN PLAINS STATES. THIS WILL ENSURE A LIGHT TO
MODERATE SOUTH WIND ACROSS THE CAROLINA COASTAL WATERS TODAY AND
TONIGHT.
SHOWERS AND EMBEDDED THUNDERSTORMS THIS MORNING SHOULD DECREASE IN
COVERAGE THIS AFTERNOON AS THE SEABREEZE CIRCULATION DEVELOPS...BUT
ANOTHER ROUND OF SCATTERED SHOWER ACTIVITY MAY DEVELOP TONIGHT. HIGH
MOISTURE CONTENT OF THE ATMOSPHERE MEANS HEAVY RAINFALL AND MARINE
VISIBILITY RESTRICTIONS ARE THE LARGEST THREATS.
SEAS CURRENTLY RANGE FROM 3-4 FT AT THE CAPE FEAR AREA BUOYS IN A
COMBINATION OF SOUTHEAST SWELL AND SOUTH WIND WAVES.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...RETURN FLOW AROUND BERMUDA HIGH PRESSURE
OFFSHORE CONTINUES THROUGH THE SHORT TERM...WITH SOUTHERLY WINDS OF
10-15 KTS COMMON EACH DAY. SEAS OF 2-3 FT TUESDAY WILL RISE TO 2-4
FT WEDNESDAY THANKS TO SLIGHTLY HIGHER WINDS. WHILE A DEAMPLIYFING
SE SWELL WILL BE PRESENT WITHIN THE WAVE SPECTRUM...SEAS WILL BE
PRIMARILY DERIVED FROM A SOUTHERLY 5-6 SEC WIND WAVE.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...SOUTHERLY WINDS AROUND 15 KTS TO START THE
PERIOD WILL VEER THROUGH THURSDAY TO THE W/SW AS A COLD FRONT
APPROACHES FROM THE NW. THIS FRONT WILL CROSS THE WATERS DURING
FRIDAY...TURNING WINDS QUICKLY TO THE WEST FRIDAY EVE WITH DECREASED
SPEEDS BEFORE WINDS INCREASE FROM THE NORTH FRIDAY NIGHT. SEAS WILL
RISE TO 3-5 FT THURSDAY NIGHT AHEAD OF THE COLD FRONT BEFORE FALLING
BACK TO 2-4 FT LATE FRIDAY THANKS TO THE OFFSHORE COMPONENT OF THE
WIND.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
NEAR TERM...TRA/MJC
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...BJR/MJC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
115 PM EDT MON MAY 20 2013
.SYNOPSIS...
A WEAKENING MID AND UPPER LEVEL TROUGH WILL SETTLE OVER CENTRAL
NORTH CAROLINA TODAY BRINGING MORE UNSETTLED CONDITIONS WITH LOCALLY
HEAVY RAIN. THE TROUGH WILL GRADUALLY MOVE TO NEAR THE COAST ON
TUESDAY REDUCING THE THREAT OF LOCALLY HEAVY RAIN.
&&
.NEAR TERM /TODAY AND TONIGHT/...
AS OF 930 AM MONDAY...
...LOCALLY HEAVY RAIN TODAY INTO THE EVENING...
AN UPPER LEVEL MESO-LOW AND ASSOCIATED 500 MB TROUGH WILL LINGER
OVER THE SOUTHEASTERN COASTAL STATES TODAY...WHILE AT THE
SURFACE...RETURN FLOW AROUND A HIGH OF THE MID-ATLANTIC COAST WILL
KEEP LIGHT GRADUAL UPSLOPE FLOW OVER CENTRAL NORTH CAROLINA. CURRENT
RUN OF THE NAM SHOWS GOOD MOISTURE TRANSPORT AND CONVERGENCE OVER
THE CENTRAL AND EASTERN PORTIONS OF THE STATE. CURRENT SPC
MESO-ANALYSIS SHOWS PW VALUES BETWEEN 1.6 AND 1.8 INCHES ACROSS THE
CWA. THIS PATTERN SHOULD HOLD FOR MUCH OF THE DAY AS CURRENT AXIS OF
PRECIPITATION OVER THE CENTRAL PORTION OF THE CWA GRADUALLY MOVES
EASTWARD INTO THE I-95 CORRIDOR. FURTHER TO THE WEST A SHORTWAVE
TROUGH IS EXPECTED TO SWING THROUGH THE WESTERN HALF OF THE STATE
PROVIDING A LITTLE MORE FORCING FOR AFTERNOON SHOWERS AND
THUNDERSTORMS. HRRR MODEL INDICATES THAT SOME HEAVIER SHOWERS WILL
DEVELOP AND MOVE INTO SOUTHWESTERN COUNTIES THIS AFTERNOON. MUCH OF
THE CENTRAL PORTION OF THE CWA HAS RECEIVED SIGNIFICANT RAINFALL
OVER THE PAST 24 HOURS BUT RAINFALL RATES HAVE BEEN LOW ENOUGH THAT
ANY FLOODING PROBLEMS HAVE BEEN NON-EXISTENT AT THIS TIME. WE WILL
CONTINUE TO MONITOR URBAN AREAS AND SMALL STREAMS FOR FLOODING
ACTIVITY WITH CONTINUED RAINFALL THIS AFTERNOON.
AT THIS HOUR MUCH OF THE AREA IS OVERCAST...BUT SOME BREAKS IN THE
CLOUDS COULD PROVIDE SOME DIFFERENTIAL HEATING BOUNDARIES THIS
AFTERNOON. WHILE SHOWERS AND THE OCCASIONAL THUNDERSTORM WILL BE
PROBABLE THIS AFTERNOON...THE LIKELIHOOD THAT ANY OF THESE STORMS
BECOMES SEVERE IS RELATIVELY LOW. WHILE THERE IS SOME
INSTABILITY...EFFECTIVE SHEAR IS VIRTUALLY NON-EXISTENT AND LAPSE
RATES ARE MODEST AT BEST. NO DCAPE TO WORK WITH MAKES SEVERE WINDS
VERY UNLIKELY. EXPECT LOWER CEILINGS TO CONTINUE TO PREVAIL THROUGH
THE MORNING AND INTO THE AFTERNOON ALSO HINDERING INSTABILITY.
DESPITE THIS...HIGHS SHOULD STILL REACH NEAR THE 80 DEGREE MARK THIS
AFTERNOON AS SOUTHWESTERLY FLOW AND WARM AIR ADVECTION HELP ELEVATE
HIGHS TODAY. -ELLIS
SHOWERS AND SCATTERED THUNDERSTORMS SHOULD DIMINISH WITH LOSS OF
HEATING THIS EVENING. WITH THE BASE OF THE TROUGH STILL OVER THE
REGION... WE WILL CONTINUE TO CARRY LOW END POPS AND QPF UNDER 0.25.
LOWS 65-70. STRATUS AND FOG WILL AGAIN BE PROBLEMATIC ESPECIALLY
09Z-13Z/TUE. -BADGETT
&&
.SHORT TERM /TUESDAY AND TUESDAY NIGHT/...
AS OF 250 AM MONDAY...
A CONTINUED WEAKENING TREND WITH THE TROUGH AND A GRADUAL SHIFT
EASTWARD WILL MEAN MORE SCATTERED AND LESS CONCENTRATED CONVECTIVE
RAINFALL ON TUESDAY AFTERNOON AND EVENING. SEVERAL MODEL SOLUTIONS
INDICATE THE SUBTROPICAL RIDGE EXTENDING WESTWARD FROM THE WESTERN
ATLANTIC OVER PORTIONS OF NC. AFTER A START TO THE DAY WITH LOW
STRATUS AND AREAS OF FOG... PARTLY SUNNY SKIES ARE EXPECTED. HIGHS
SHOULD REBOUND INTO THE LOWER TO MID 80S. HOWEVER... DEW POINTS WILL
STILL BE IN THE MID TO UPPER 60S. THE COOLER MET/NAM GUIDANCE LOOKS
MORE IN LINE WITH THE CURRENT EXPECTATIONS WITH THE SSW FLOW AND
PLENTY OF LOW LEVEL MOISTURE AND BROKEN AFTERNOON CLOUDINESS. WIDELY
SCATTERED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED. THIS
ACTIVITY WILL DIMINISH TUESDAY EVENING WITH LOSS OF HEATING. PARTLY
CLOUDY SKIES WITH AREAS OF FOG AGAIN EXPECTED LATE AT NIGHT. LOWS IN
THE MID 60S.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 255 AM MONDAY...
UPPER LEVEL RIDGE BUILDS BRIEFLY OVER THE AREA ON WEDNESDAY... WHICH
SHOULD DIMINISH THE COVERAGE OF CONVECTION... ALTHOUGH DIURNALLY
DRIVEN THUNDERSTORMS CONTINUE TO BE POSSIBLE WITH THE MOIST AIRMASS
OVER THE AREA. PWATS WILL REMAIN NEAR 1.5... 2 STANDARD DEVIATIONS
ABOVE NORMAL FOR THIS TIME OF YEAR. WITH WEAK SHEAR... EXPECTING
PULSE TYPE STORMS. HIGHS IN THE MID 80S... LOWS MID 60S.
UPPER LEVEL RIDGE SHIFTS OFFSHORE THURSDAY. AFTERNOON THUNDERSTORMS
CONTINUE TO BE POSSIBLE IN THE AFTERNOON THURSDAY AS PWATS REMAIN
ABOVE NORMAL. BULK SHEAR INCREASES TO 25 TO 30 KTS... WHICH MAY
SUPPORT SOME MULTICELL ORGANIZATION. THICKNESSES REMAIN NEAR TO
SLIGHTLY ABOVE AVERAGE THURSDAY AND FRIDAY... FAVORING TEMPERATURES
CONTINUING TO A BE A FEW DEGREES ABOVE NORMAL... WITH HIGHS IN THE
80S AND LOWS IN THE UPPER 60S. THE TROUGH OVER THE MIDWEST MOVES
EASTWARD ON THURSDAY... AND THE ATTENDANT COLD FRONT PUSHES ACROSS
THE REGION FRIDAY. TIMING HAS TRENDED FASTER DURING TODAYS MODEL
RUNS... WITH THE FRONT MAKING IT THROUGH THE AREA EARLY FRIDAY...
AND TO THE CAROLINA COAST FRIDAY MORNING. STRONGEST DYNAMIC FORCING
REMAINS NORTH OVER NEW ENGLAND... AND WITH THE TIMING NOW LOOKING
MORE DIURNALLY UNFAVORABLE... DO NOT EXPECT A THREAT OF SEVERE
WEATHER.
&&
.AVIATION /18Z MONDAY THROUGH FRIDAY/...
AS OF 115 PM MONDAY...
24 HOUR TAF PERIOD:
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL PREVAIL THIS
AFTERNOON ACROSS THE CWA AT ALL TERMINALS. CURRENTLY RADAR SHOWS
SHORTWAVE CURRENTLY MOVING ACROSS THE TRIAD WITH STRONGER CELLS ON
THE EASTERN SIDE WITH LINGERING SHOWERS TO THE WEST. FOR THE TRIAD
STRONGEST SHOWERS AND THUNDERSTORMS MOST LIKELY MOVING THROUGH NOW
THROUGH THE NEXT COUPLE OF HOURS AND DOWN TRENDING TO MOSTLY LIGHT
SHOWERS THEREAFTER. FURTHER TO THE EAST CONDITIONS SHOULD REMAIN
MORE FAVORABLE FOR HEAVIER SHOWERS AND THUNDERSTORMS THROUGH EARLY
EVENING. EXPECT CEILINGS TO BOUNCE BETWEEN VFR AND MVFR AND SINKING
OCCASIONALLY TO IFR IN THE STRONGER CELLS. WILL COVER THIS WITH A
TEMPO GROUP IN THE TAFS WITH VFR/MVFR PREVAILING. WINDS WILL REMAIN
GENERALLY SOUTHWESTERLY AT 5-10 KNOTS WITH OCCASIONAL GUSTS OF 15-20
IN HEAVY SHOWERS.
AFTER PRECIPITATION WINDS DOWN TONIGHT EXPECT SOME LOW
CEILINGS/VISIBILITIES...GENERALLY AFTER 3Z. EXPECT SOME FOG IN THE
WEST WITH MORE OF A LOW STRATUS SITUATION FURTHER TO THE EAST.
CONDITIONS SHOULD REMAIN SUB VFR EVERYWHERE UNTIL 15Z WHEN VFR
CEILINGS AND VISIBILITIES SHOULD RETURN. ALTHOUGH CONDITIONS WILL BE
IMPROVING AND GENERALLY DRYING...THE MESO-LOW WILL LINGER OVERHEAD
KEEPING THE CHANCE FOR SHOWERS ALIVE THROUGH THE END OF THE TAF
PERIOD.
LONG TERM:
LOW STRATUS AND FOG ARE EXPECTED TO RETURN TUESDAY NIGHT INTO
WEDNESDAY. WEDNESDAY WILL BE THE DRIEST DAY BUT WILL STILL HAVE THE
CHANCE FOR DIURNAL SHOWERS AND STORMS. THURSDAY AND THURSDAY NIGHT
WILL FEATURE THE PASSAGE OF A COLD FRONT AND A RETURN TO SUB-VFR
CONDITIONS. VFR CONDITIONS WILL GRADUALLY RETURN TO THE AREA ON
FRIDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BADGETT
NEAR TERM...ELLIS/BADGETT
SHORT TERM...BADGETT
LONG TERM...SEC
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
539 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 540 PM CDT MON MAY 20 2013
UPDATE LATE THIS AFTERNOON DUE TO STRONG WINDS. WILL EXTEND THE
WIND ADVISORY FARTHER SOUTH TO INCLUDE AREAS ALONG AND NORTH OF
INTERSTATE 94.
VERY STRONG WINDS ACROSS FAR NORTH CENTRAL NORTH DAKOTA LATE THIS
AFTERNOON WITH WIND GUST TO 48KTS RECORDED AT ROLLA. CURRENT GUSTS
HAVE SUBSIDED BACK TO AROUND 40-42 KNOTS. WILL CONTINUE TO MONITOR
FOR POSSIBLE HIGH WIND WARNING THIS EVENING.
LATEST RAP ANALYSIS SHOWS AROUND 40-45 KNOTS OF WIND AT 925 MB
THROUGH MID EVENING...MAINLY ALONG AND EAST OF THE HIGHWAY 83
CORRIDOR AND ALONG AND NORTH OF INTERSTATE 94. ALSO 850 KNOT WINDS
INCREASE EARLY THIS EVENING ACROSS MUCH OF CENTRAL NORTH DAKOTA.
AFTER COORDINATION WITH FGF...WILL EXTEND THE CURRENT WIND
ADVISORY FARTHER SOUTH TO ALONG AND NORTH OF INTERSTATE 94...AND
KEEP AN EYE ON WINDS ACROSS THE FAR NORTH CENTRAL...HOLDING OFF ON
A HIGH WIND WARNING AT THIS TIME.
OTHERWISE NO SIGNIFICANT CHANGES TO THE FORECAST.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE HIGHLIGHT OF THE SHORT TERM CONTINUES TO BE THE IMPACTS OF THE
ONGOING RAINFALL EVENT.
OVERALL THE GUIDANCE IS IN GOOD AGREEMENT...AND FOLLOWED A BLEND
OF THE 12 UTC GFS/GEM/ECMWF AND 15 UTC SREF FOR ALL FIELDS.
CURRENTLY THE STACKED LOW ACROSS FAR NORTHEAST SOUTH DAKOTA IS
EXPECTED TO SLOWLY PROPAGATE INTO CENTRAL MINNESOTA THROUGH
TUESDAY. WRAP AROUND RAINFALL IS EXPECTED TO SLOWLY DOWNTREND
THROUGH THE NIGHT AND INTO TUESDAY WITH AN ADDITIONAL ONE HALF TO
THREE QUARTERS OF AN INCH OF RAINFALL EXPECTED. SEE THE HYDROLOGY
DISCUSSION BELOW FOR DETAILS.
FOR THIS EVENING AND TONIGHT...DID MAINTAIN THE WIND ADVISORY FOR
THE WEST AND NORTH. THE WIND FIELD ACROSS THESE AREAS CONTINUES TO
STRENGTHEN WITH 40-45 KTS AT THE TOP OF A SHALLOW MIXED LAYER AS
DEPICTED BY THE 12 UTC NAM/GFS BUFR SOUNDINGS. THE STRONGEST WINDS
ARE EXPECTED ACROSS THE TURTLE MOUNTAINS WHERE GUSTS TO NEAR 50
MPH ARE POSSIBLE THROUGH EARLY EVENING.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON MAY 20 2013
THE MAIN FORECAST ISSUE THROUGH THE LONG TERM PERIOD WILL BE ONGOING
RIVER AND OVERLAND FLOODING CONCERNS. SEE HYDROLOGY DISCUSSION BELOW
FOR DETAILS. THEN ATTENTION TURNS TO THE UPCOMING WEEKEND AND THE
POSSIBILITY FOR SCATTERED THUNDERSTORMS AND POSSIBLE SEVERE WEATHER.
THERE IS FAIRLY GOOD MODEL AGREEMENT REGARDING THE POSITION AND
MOVEMENT OF THE CLOSED UPPER LEVEL LOW...ASSOCIATED WITH THE
PERSISTENT RAINS FOR THE PAST SEVERAL DAYS. THE UPPER LOW IS
FORECAST TO BE OVER THE SD/MN BORDER TUESDAY EVENING...THEN BECOME
MORE OF AN OPEN WAVE BY WEDNESDAY EVENING OVER IA/WI/IL AND THE
WESTERN GREAT LAKES. THIS SCENARIO WILL MEAN THE VERY HIGH/LIKELY
CHANCES OF RAIN TUESDAY NIGHT IN THE JAMES RIVER BASIN WILL LESSEN
TO SCATTERED IN NATURE BY WEDNESDAY. THE REST OF WESTERN AND CENTRAL
NORTH DAKOTA SHOULD SEE A DECREASE IN COVERAGE OF THE SHOWERS
TUESDAY NIGHT. SLIGHT CHANCES TO SCATTERED SHOWERS WEDNESDAY AS THE
SYSTEM MOVES EAST OF THE REGION.
BY WEDNESDAY EVENING AS THE UPPER LEVEL LOW/TROUGH MOVES EAST...A
WEAK UPPER LEVEL RIDGE WILL BUILD ACROSS THE NORTHERN PLAINS. THIS
WILL BE SHORT-LIVED AS ANOTHER LARGE UPPER LEVEL LOW/TROUGH SYSTEM
MOVES INTO THE PACIFIC NORTHWEST AND ROCKIES. THUS NO PRECIPITATION
MENTION FOR WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
FRIDAY THROUGH THE WEEKEND AND INTO MONDAY...THE UPPER LEVEL LOW
OVER THE ROCKIES IS FORECAST TO REMAIN IN PLACE...SETTING UP A
PROLONGED PERIOD OF SOUTHWESTERLY FLOW ALOFT FOR NORTH DAKOTA. THIS
WILL MEAN PERIODIC UPPER LEVEL SHORTWAVE ENERGY MOVING NORTHEASTWARD
THROUGH THE MEAN FLOW. AT THE SURFACE...THIS WILL RESULT IN BROAD
LOW PRESSURE ACROSS THE PLAINS...ALLOWING PLENTY OF GULF OF MEXICO
MOISTURE TO STREAM NORTHWARD. A PROLONGED LOW LEVEL JET AT H925-H850
WILL HELP TRANSPORT MOISTURE AND ENERGY NORTHWARD UP THE PLAINS.
THUS PERIODIC EPISODES OF SCATTERED THUNDERSTORMS WILL BE IN THE
FORECAST FRIDAY THROUGH THE MEMORIAL DAY WEEKEND.
WHILE TOO FAR OUT FOR MUCH CERTAINTY IN NARROWING DOWN SPECIFIC
AREAS OF CONCERN...SURFACE DEWPOINTS RISING INTO THE 50S BY FRIDAY
AND FORECAST CAPE DEVELOPING FROM THE SOUTHERN...CENTRAL...TO THE
NORTHERN PLAINS WOULD SUGGEST SOME SEVERE THUNDERSTORM ACTIVITY OVER
A BROAD AREA OF THE PLAINS FRIDAY AND SATURDAY. STAY TUNED FOR LATER
FORECASTS AND STORM PREDICTION CENTER OUTLOOKS FOR THE POTENTIAL FOR
SEVERE THUNDERSTORMS THIS COMING WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 540 PM CDT MON MAY 20 2013
LIGHT TO MODERATE RAINFALL WILL CONTINUE OVER ALL TERMINALS
THROUGH THE TAF PERIOD WITH MVFR/IFR CIGS/VSBYS. WIND GUSTS OF
30-40 KTS ARE POSSIBLE AT ALL TAF SITES LATE THIS AFTERNOON AND
THIS EVENING.
&&
.HYDROLOGY...
ISSUED AT 330 PM CDT MON MAY 20 2013
DID MAINTAIN THE FLOOD WATCH FOR ALL OF WESTERN AND CENTRAL NORTH
DAKOTA THROUGH TONIGHT. CALLS TO AREA EMERGENCY MANAGERS REVEAL THAT
FOR THE MOST PART...COUNTY AND TOWNSHIP ROAD IMPACTS ARE LIMITED.
HOWEVER...AS SOILS CONTINUE TO SATURATE...OVERLAND FLOOD CONCERNS
COULD INCREASE THROUGH THE NIGHT. FURTHERMORE...REPORTS HAVE BEEN
COMING IN OF WATER ENTERING BASEMENTS ACROSS THE AREA WITH THE
SATURATED GROUND. ADDITIONAL RIVER AND STREAM RISES ARE EXPECTED
OVER THE COMING DAYS. FOR THE MOST PART WITHIN BANK RISES ARE
ANTICIPATED. HOWEVER...THE SOURIS RIVER AT TOWNER IS EXPECTED TO
RISE ABOVE FLOOD STAGE AGAIN...THE PIPESTEM CREEK NEAR PINGREE IS
FORECAST TO RISE ABOVE MINOR FLOOD STAGE TOMORROW AFTERNOON WITH
THE WILLOW CREEK NEAR WILLOW CITY POSSIBLY APPROACHING FLOOD STAGE
BY WEDNESDAY EVENING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH TUESDAY MORNING FOR NDZ001>005-009>013-
017>023-025-031>037-040>048-050-051.
WIND ADVISORY UNTIL 1 AM CDT /MIDNIGHT MDT/ TUESDAY FOR
NDZ001>005-009>013-017>023-025-031>037-040-041-043-044.
&&
$$
UPDATE...TWH
SHORT TERM...AYD
LONG TERM...JV
AVIATION...TWH
HYDROLOGY...AYD
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
533 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 533 PM CDT MON MAY 20 2013
WATCHING WINDS ACROSS THE NW FA VERY CLOSELY THIS EVENING. THERE
IS AN AREA FROM ROLLA TO LANGDON WHERE THE AWOS SITES HAVE BEEN
FLIRTING WITH HIGH WIND WARNING CRITERIA (BOTH SUSTAINED AND
GUSTS). THE RAP INDICATES THE ADIABATIC LAYER WILL DEEPEN OVER
THE NEXT SEVERAL HOURS...AND 925MB WINDS WILL INCREASE. THE LAV
GUIDANCE APPEARS TO HAVE A DECENT HANDLE ON THE CURRENT
WINDS...AND INDICATES 40 MPH WITH GUSTS TO 60 MPH ACROSS THIS AREA
AT 00Z. CONFIDENCE IS NOT EXTREMELY HIGH THAT THIS WILL
OCCUR...BUT WILL MONITOR IT CLOSELY. THE RAP AND LAV GUIDANCE ALSO
INDICATE WIND ADVISORY CRITERIA WILL BE A BIT FURTHER SOUTH THAN
ANTICIPATED AS THE SURFACE LOW SLOWLY WARBLES SOUTHWARD...AND WILL
EXPAND THE WIND ADVISORY INTO THE COOPERSTOWN AND VALLEY CITY
AREA.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 339 AM CDT MON MAY 20 2013
VERY SEVERE FLOODING SITUATION OVER PARTS OF NORTHEASTERN NORTH
DAKOTA. KMVX 88D STORM PRECIP TOTALS EITHER VIA LEGACY STP OR THE
NEW DUAL POL ARE WOEFULLY UNDERDONE ESPECIALLY IN NORTHEASTERN
NORTH DAKOTA. SENT OUT A LONG LIST OF RAINFALL REPORTS SO FAR
WIDESPREAD 1-3 INCHES WITH POCKET OF 4-6 INCHES OR MORE FROM HOMME
DAM NEAR PARK RIVER ND UP THROUGH CRYSTAL TO MOUNTAIN ND TO
WALHALLA. LOTS OF CREEK FLOODING AND OVERLAND FLOODING THERE AND
UPDATED AREAL FLOOD WARNING FOR THIS AREA.
FOR TONIGHT EXPECT CONTINUED RAIN...THOUGH A BIT DRIER AIR ALOFT
SHOULD MEAN RAIN WILL BECOME MORE SCATTERED AND LIGHTER AS THE
NIGHT GOES ALONG. SOME THUNDER IN DRY SLOT FROM LITTLE FALLS TO ST
CLOUD AND SOME ISOLD THUNDER MAY MAKE IT INTO SOUTHEASTERN ZONES
THIS EVE. OTHERWISE JUST RAIN. ANOTHER HALF INCH OR A BIT MORE
THRU TONIGHT ISOLD 1 INCH MORE IN THE SOUTH TONIGHT. THE SOUTHERN
AREAS HAVE HAD THE LEAST AND CAN TAKE IT. WILL MAINTAIN AREAL
FLOOD WATCH AS ISSUED EARLIER.
FOR WINDS EXPANDED WIND ADV TO ROSEAU COUNTY AS ROX AWOS CONTINUES
TO SEE WIND GUSTS OVER 40 KTS AND SUSTAINED WINDS 25-30 KTS.
EXPECT TO SEE WINDY CONDITIONS THRU 03Z BEFORE THEY DIMINISH.
WATER VAPOR SHOWS UPR LOW AND SFC LOW STACKED SOUTH OF SISSETON
AND THIS LOW WILL BE STATIONARY AND BEGIN TO DRIFT SOUTH AND EAST
LATE TONIGHT INTO TUESDAY. WILL SEE LIGHTER RAINFALL ON
TUESDAY....BUT FOCUS MORE ON THE SOUTH.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 339 AM CDT MON MAY 20 2013
SYSTEM WILL DROP SOUTH ON WEDNESDAY WITH CLEARING AND DRYING
MOVING SOUTH. MAINLY DRY WED NIGH INTO THURSDAY WITH HIGH PRESSURE
COMING IN. FOR THU NIGHT INTO EARLY FRI MOST OF THE FA SHOULD
REMAIN DRY WITH THE 500MB RIDGE AXIS STILL OVER THE AREA. HOWEVER
THIS IS FAIRLY SHORT LIVED AS THE FLOW QUICKLY BEGINS TO BECOME
MORE SOUTHWEST. THIS SWITCH TO SOUTHWEST FLOW WILL BRING ACTIVE
WEATHER BACK INTO THE FA FOR BASICALLY THE REMAINDER OF THE LONG
TERM PERIOD. OPERATIONAL MODEL RUNS TODAY ARE SHOWING THE
POSSIBILITY OF NORTHEAST FLOW ERODING SOME OF THIS PCPN
POTENTIAL...ESPECIALLY IN THE NORTHEAST FA. THEREFORE THE BEST
CHANCES FOR PCPN SHOULD PROBABLY BE OVER THE WESTERN FA WITH
LESSER CHANCES TO THE EAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 104 PM CDT MON MAY 20 2013
THE HIGHEST WIND SPEEDS SHOULD BE AT KDVL BUT KGFK/KTVF WILL STILL
SEE SOME PRETTY GUSTY EAST-NE WINDS. KBJI AND KFAR WILL BE QUITE A
BIT LOWER FOR WIND SPEEDS DUE TO THEIR CLOSER PROXIMITY TO THE SFC
LOW. EXACT VSBYS AND CEILINGS TOUGH TO CALL BUT IT DEFINITELY LOOKS
WET. WILL STICK WITH STEADY RAIN AT ALL TAF SITES EVEN THOUGH THERE
MAY BE SOME TEMPORARY BREAKS. CLOUD HEIGHTS SEEM TO BE INCREASING A
LITTLE THIS AFTERNOON BUT THEY SHOULD GO DOWN AGAIN TONIGHT.
&&
.HYDROLOGY...
ISSUED AT 339 AM CDT MON MAY 20 2013
RIVER FLOOD WATCHES HAVE BEEN CANCELLED FOR THE RED RIVER AT
WAHPETON AND ITS SOUTHERN VALLEY MINNESOTA TRIBUTARIES.
RAINFALL AMOUNTS ARE EITHER INSUFFICIENT OR RUNOFF DUBIOUS TO
FORCE THESE POINTS TO FLOOD STAGE DURING THIS EVENT.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...FLOOD WATCH THROUGH TUESDAY EVENING FOR NDZ006>008-014>016-024-
026>030-038-039-049-052>054.
WIND ADVISORY UNTIL 1 AM CDT TUESDAY FOR NDZ006>008-014>016-024-
026-028-038-054.
MN...FLOOD WATCH THROUGH TUESDAY EVENING FOR MNZ001>009-013>017-
022>024-027>032-040.
WIND ADVISORY UNTIL 1 AM CDT TUESDAY FOR MNZ004-005-007.
&&
$$
UPDATE...TG
SHORT TERM...RIDDLE
LONG TERM...RIDDLE/GODON
AVIATION...GODON
HYDROLOGY...WJB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
359 PM EDT MON MAY 20 2013
.SYNOPSIS...
THE AIRMASS WILL BECOME INCREASINGLY MOIST AND UNSTABLE THROUGH MID
WEEK AS AN AREA OF LOW PRESSURE OVER THE UPPER MIDWEST SLOWLY
APPROACHES THE REGION. THIS LOW PRESSURE SYSTEM WILL TRACK THROUGH
THE EASTERN GREAT LAKES LATE WEDNESDAY AND PUSH A COLD FRONT SOUTH
ACROSS THE AREA. HIGH PRESSURE WILL RETURN FOR THE END OF THE
WEEK.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A HOT AND HUMID AIRMASS IS IN PLACE OVER THE REGION THIS AFTERNOON
AS WE REMAIN BENEATH THE UPPER LEVEL RIDGE. DEWPOINTS ARE IN THE MID
AND UPPER 60S ACROSS MOST OF THE AREA AND THE SPC RUC ANALYSIS
INDICATES OVER 2000 J/KG OF ML CAPE. DESPITE THIS...SPECIAL 18Z
SOUNDING OUT OF DTX INDICATES A STRONG CAP IS IN PLACE BETWEEN
875-650MB WHICH IS REPRESENTATIVE OF THE AIRMASS ACROSS NRN OHIO.
THE CU FIELD HAS ACTUALLY BEEN CLEARING ACROSS NW OHIO WHERE
DEWPOINTS HAVE MIXED DOWN INTO THE MID 60S. A LINE OF THUNDERSTORMS
IS DEVELOPING ACROSS WESTERN LOWER MICHIGAN AS A SPOKE OF ENERGY
EJECTS OUT OF THE UPPER TROUGH. HI-RES MODELS INDICATE THIS BAND
WILL CONTINUE TO FILL IN TO THE SOUTH ALONG THE ENHANCED CU FIELD TO
THE WEST AND CLIP THE TOLEDO AREA BEFORE MOVING EAST ACROSS LAKE
ERIE BETWEEN 00-03Z. IF THIS OCCURS...THERE IS THE POTENTIAL FOR
SOME THUNDERSTORMS TO BE SEVERE ALTHOUGH INSTABILITY WILL BE
DECREASING AND WIND FIELD IN NW OHIO IS NOT AS FAVORABLE. WILL CARRY
POPS ACROSS MAINLY THE NORTHERN CWA TONIGHT TO ACCOUNT FOR THIS
ACTIVITY WITH POPS INCREASING ACROSS WESTERN AREAS TOWARDS DAWN AS A
LOW LEVEL JET APPROACHES. TEMPERATURES WILL BE MILD OVERNIGHT WITH
LOWS ONLY DROPPING INTO THE UPPER 60S/NEAR 70 DEGREES.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/...
UPPER LEVEL RIDGE AXIS WILL SHIFT EAST OF THE AREA ON TUESDAY AS THE
APPROACHING LOW PRESSURE SYSTEM MOVES INTO THE WESTERN LAKES REGION.
SHORTWAVE ENERGY IS EXPECTED TO EJECT OUT OF THE TROUGH TOWARDS THE
AREA AND HELP TO INITIATE CONVECTION. MODELS ALSO INDICATE A LOW
LEVEL JET WILL CLIP NW OHIO ON TUESDAY MORNING AND CONVECTION COULD
MOVE INTO THE AREA FROM THE WEST DURING THE MORNING. THERE IS SOME
UNCERTAINTY AS TO HOW ACTIVITY WILL EVOLVE...IF IT WILL CONTINUE
EASTWARD DOWN WIND OF THE LLJ OR IF WAIT UNTIL WE DESTABILIZE TO
INITIATE. CLOUD COVER COULD BE A LIMITING FACTOR FOR DESTABILIZATION
BUT EXPECT WE WILL STILL SEE STRONG WITH TEMPERATURES IN THE LOW 80S
AND DEWPOINTS IN THE 60S. A SPEED MAX AT 500MB WILL ALSO MOVE ACROSS
NW OHIO AND HELP TO SUPPORT CONVECTION. GIVEN THE FAVORABLE SHEAR
AND MODERATE INSTABILITY THE WESTERN HALF OF THE FORECAST AREA IS IN
A SLIGHT RISK FOR SEVERE WEATHER. EXPECTING THE PRIMARY THREAT TO BE
WIND GIVEN THE STRONG FLOW ALOFT. FREEZING LEVELS ARE HIGH NEAR
13.5KFT SO ONLY THE STRONGEST STORMS WILL BE ABLE TO PRODUCE HAIL
AND THE SURFACE FRONT REMAINS TO OUR WEST SO LOW LEVEL SHEAR WILL
NOT BE VERY FAVORABLE FOR TORNADOGENESIS. WITH THAT SAID...A LOW
CHANCE DOES STILL REMAIN FOR BOTH HAIL AND TORNADOES. SHEAR IS
CONSIDERABLY LOWER ACROSS THE EASTERN CWA AND STORM MOTION WILL BE
TO THE NORTHEAST AT ABOUT 35 MPH SO THE SEVERE THREAT WILL BE
LOWER...MAINLY EAST OF I-71.
EXPECTING A LULL IN SHOWERS AND THUNDERSTORMS ON TUESDAY NIGHT SO
WILL JUST HOLD ONTO A CHANCE POP. AN UPPER LEVEL JET WILL ROUND THE
BASE OF THE TROUGH TUESDAY NIGHT WITH THE TROUGH AXIS SWINGING
NORTHEAST TOWARDS THE OHIO VALLEY ON WEDNESDAY. CLOUD COVER IS AGAIN
IN QUESTION BUT LARGE SCALE ASCENT WILL BE STRONGER ON WEDNESDAY AND
EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS DURING THE DAY. THERE IS
AGAIN A SLIGHT RISK OF SEVERE STORMS ACROSS NEARLY THE ENTIRE
FORECAST AREA WITH BETTER INSTABILITY FOCUSED ACROSS THE EAST.
THE LOW PRESSURE SYSTEM WILL MOVE NORTHEAST THROUGH THE CENTRAL
GREAT LAKES ON WEDNESDAY AND FINALLY PUSH A COLD FRONT SOUTH ACROSS
THE AREA WEDNESDAY NIGHT AND THURSDAY. INSTABILITY AXIS WILL BE TO
OUR EAST FINALLY BY THURSDAY SO ONLY CARRIED THUNDERSTORMS IN THE
SOUTHERN COUNTIES WITH HIGHS NEAR TO JUST SLIGHTLY BELOW NORMAL.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
BY THE START OF THE LONG TERM PERIOD...HIGH PRESSURE IS EXPECTED TO
BE SITUATED OVER THE CENTRAL GREAT LAKES. THIS WILL RESULT IN DRY
NORTHERLY FLOW FOR THE AREA FOR THE ENTIRE WEEKEND. THE ENTIRE FOUR
DAY LONG TERM PERIOD SHOULD BE DRY. TEMPS WILL STRUGGLE TO GET OUT
OF THE MIDDLE 60S ON FRIDAY AND OUT OF THE UPPER 60S BOTH SATURDAY
AND SUNDAY. READINGS SHOULD RETURN TO CLOSE TO NORMAL ON MONDAY AS
A WARM FRONT APPROACHES FROM THE SOUTH.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
AREA OF STRATUS OVER N-CENTRAL HAS LIFTED TO MVFR AND CONTINUES
TO ERODE FROM THE EDGES. EXPECT ALL AREAS TO BE VFR IN AN HOUR OR
TWO. STILL A LOT OF QUESTIONS ABOUT THUNDERSTORM ACTIVITY DURING
THE PERIOD. BEST GUESS RIGHT NOW IS THAT NW OH COULD SEE SOME
STORMS TOWARD EVENING. WILL GO WITH A MENTION OVER ABOUT THE WEST
HALF OF THE AREA. EASTERN AREAS SHOULD BE CAPPED AND WILL REMAIN
DRY THROUGH 18Z TUESDAY. ANOTHER ROUND OF STORMS COULD AFFECT
WESTERN AREAS BY MIDDAY TUESDAY. S TO SW FLOW WILL CONTINUE.
SPEEDS SHOULD BE 5 KNOTS OR LESS LATER TONIGHT WHICH SHOULD ALLOW
SOME PATCHY MVFR FOG TO DEVELOP BEFORE DAYBREAK. SPEEDS WILL
INCREASE ON TUESDAY MORNING WITH GUSTS TO 20 KNOTS LIKELY. KERI
ALREADLY HAS A LAKE BREEZE. DO NOT THINK IT WILL REACH KCLE TODAY.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS OVERNIGHT THROUGH
THURSDAY.
&&
.MARINE...
SOUTH TO SOUTHWEST FLOW WILL CONTINUE ON THE LAKE TILL A COLD FRONT
CROSSES THE LAKE SOMETIME EARLY THURSDAY. SPEEDS SHOULD MAINLY BE
UNDER 15 KNOTS TILL THE FRONT ARRIVES. ONSHORE FLOW COULD DEVELOP ON
THE NEARSHORE WATERS BOTH TUESDAY AND WEDNESDAY. STRONG TO SEVERE
STORMS APPEAR POSSIBLE BOTH TUESDAY AND WEDNESDAY. BOATERS WILL
NEED TO REMAIN ALERT. SMALL CRAFT ADVISORIES APPEAR LIKELY FOR
THURSDAY AND FRIDAY WITH STRONG NORTHWEST FLOW BEHIND THE FRONT.
SOME SHOWERS ARE LIKELY ON THURSDAY. FRIDAY AND SATURDAY WILL BE
DRY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC
SHORT TERM...KEC
LONG TERM...KUBINA
AVIATION...KUBINA
MARINE...KUBINA
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
309 PM EDT MON MAY 20 2013
.SYNOPSIS...
A WARM AND HUMID AIRMASS WILL REMAIN IN PLACE BEFORE A COLD FRONT
ARRIVES ON THURSDAY. MID LEVEL RIDGING WILL SLIDE EAST OF OUR AREA
TONIGHT AS LOW PRESSURE SLOWLY MOVES SOUTH AND EAST ACROSS THE
NORTHERN PLAINS. CHANCES FOR PRECIPITATION WILL INCREASE AS THIS
LOW APPROACHES OUR AREA OVER THE NEXT COUPLE OF DAYS.
&&
.NEAR TERM /THROUGH TONIGHT/...
MID LEVEL RIDGE EXTENDING ACROSS THE SOUTHEASTERN CONUS AND INTO
OUR FORECAST AREA IS KEEPING CONVECTION OUT OF OUR AREA THIS
AFTERNOON DESPITE AN UNSTABLE AIRMASS. A CU DECK WILL THIN LATE
THIS AFTERNOON AND EVENING AS WE BEGIN TO LOSE THE PEAK HEATING OF
THE DAY. TONIGHT...MOST CONVECTIVE MODELS ARE INDICATING
DEVELOPMENT OF THUNDERSTORMS WELL WEST OF OUR AREA ASSOCIATED WITH
A DISTURBANCE ROUNDING THE BASE OF A TROUGH EXTENDING SOUTH OF LOW
PRESSURE ACROSS THE NORTHERN PLAINS. THIS CONVECTION IS EXPECTED
TO HEAD EAST TO NORTHEAST THROUGHOUT THE NIGHT AS PLENTY OF
ELEVATED INSTABILITY WILL BE IN PLACE. WHATEVER IS LEFT OF THIS
CONVECTION LATE TONIGHT MAY MAKE IT INTO OUR WESTERN ZONES AFTER
MIDNIGHT. WAS FAIRLY AGGRESSIVE IN THE FORECAST ON BRINGING
SHOWERS AND THUNDERSTORMS INTO THE WESTERN ZONES LATE TONIGHT
WHILE GRADUALLY WEAKENING THEM AS THEY SHIFT EASTWARD ACROSS OUR
AREA TUESDAY MORNING.
ANOTHER MILD NIGHT IS FORECAST FOR TONIGHT WITH OVERNIGHT LOWS
IN THE MID TO UPPER 60S.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
OVERALL PATTERN FOR THE SHORT TERM TIME PERIOD IS FOR A LOW OVER
THE NORTHERN PLAINS TO SLOWLY SHEAR EASTWARD TUESDAY THROUGH
TUESDAY NIGHT...BEFORE GETTING ABSORBED INTO A DEEPENING TROUGH
ACROSS THE GREAT LAKES. AS THIS SYSTEM BEGINS TO GET SHEARED INTO
SOUTHWESTERLY FLOW ACROSS OUR REGION...TIMING OF INDIVIDUAL PIECES
OF ENERGY AND ASSOCIATED CONVECTION BECOMES UNCERTAIN.
BASED ON THE NEAR TERM FORECAST DECAYING CONVECTION ACROSS OUR
ZONES TUESDAY MORNING...THERE WOULD BE A PORTION OF THE DAY
TUESDAY WHERE THE BOUNDARY LAYER WILL BE WORKED OVER. THEREFORE
THERE MAY BE SEVERAL HOURS DURING THE FIRST PART OF THE DAY
TUESDAY WHERE LITTLE TO NO CONVECTION IS OCCURRING IN OUR FORECAST
AREA. THIS SOLUTION IS BEING INDICATED BY THE MAJORITY OF COMPUTER
MODELS. BY LATE TUESDAY AFTERNOON INSTABILITY WOULD HAVE INCREASED
AND SUFFICIENT RECOVERY OF THE BOUNDARY LAYER IS EXPECTED TO HAVE
OCCURRED. FORCING ASSOCIATED WITH ANY SHORTWAVE ENERGY EJECTING
EAST FROM THE LOW OVER THE PLAINS WILL HELP TO TRIGGER CONVECTIVE
DEVELOP LATE TUESDAY AFTERNOON. ALTHOUGH EXACT TIMING AND
PLACEMENT OF THE CONVECTION IS HIGHLY UNCERTAIN AT THIS TIME...UP
TO 45 KT OF 0-6 KM SHEAR MAY BE PRESENT ACROSS THE NORTHWESTERN
HALF OF OUR FORECAST AREA. THEREFORE...IF CONVECTION DOES GET GOING
TUESDAY AFTERNOON AND EVENING ACROSS OUR NORTHWEST...THERE WILL
BE THE POTENTIAL FOR SOME OF THESE STORMS TO BECOME SEVERE. THE
MAIN THREAT FROM THESE STORMS WOULD BE DAMAGING WIND AND ISOLATED
LARGE HAIL. THIS THREAT IS BEING HIGHLIGHTED IN THE HWO.
CHANCES FOR SHOWER AND THUNDERSTORMS WILL CONTINUE INTO TUESDAY
NIGHT AND INTO THE DAY ON WEDNESDAY AS THE LOW PROGRESSES NEARER
TO OUR AREA. SHEAR AND INSTABILITY WILL DECREASE ON TUESDAY NIGHT
AND WEDNESDAY....WHICH SHOULD LESSEN THE OVERALL SEVERE THREAT.
HOWEVER...ON WEDNESDAY THERE MAY STILL BE SUFFICIENT INSTABILITY
TO COMBINE WITH ABOUT 35 KT OF 0-6 KM SHEAR TO PRODUCE ISOLATED
CHANCES FOR DAMAGING WINDS AND LARGE HAIL SHOULD STORMS GET
ORGANIZED.
BY WEDNESDAY EVENING THE BEST CHANCES FOR PRECIPITATION WILL SHIFT
EAST OF OUR AREA ALONG WITH THE BEST FORCING.
TEMPERATURES WILL BE ON A DOWNWARD TREND THROUGHOUT THE SHORT TERM
TIME PERIOD. ON TUESDAY EXPECT UPPER 80S ACROSS THE EAST TO LOWER
80S ACROSS THE WEST. BY WEDNESDAY...CLOUD COVER AND PRECIPITATION
WILL KEEP TEMPERATURES LOWER THAN TUESDAY. OVERNIGHT LOWS WILL
CONTINUE TO BE MILD BOTH TUESDAY AND WEDNESDAY NIGHT AS WE REMAIN
IN THIS WARM AND HUMID AIRMASS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE UPPER LEVEL TROUGH WILL PIVOT EAST ACROSS OUR AREA THROUGH THE
DAY ON THURSDAY. THIS COMBINED WITH SOME LINGERING
INSTABILITIES...WILL KEEP THE THREAT OF SHOWERS AND A FEW
THUNDERSTORMS GOING THROUGH THE AFTERNOON. AS THE TROUGH BEGINS TO
SHIFT EAST AND WE LOSE THE INSTABILITY...PCPN SHOULD TAPER OFF TO A
FEW SHOWERS THURSDAY NIGHT. COOLER AIR WILL BEGIN FILTERING INTO THE
AREA THROUGH THE DAY ON THURSDAY WITH HIGHS RANGING FROM THE UPPER
60S NORTHWEST TO LOW TO MID 70S SOUTHEAST.
SURFACE HIGH PRESSURE WILL BUILD DOWN FROM THE NORTH AND INTO OUR
AREA FRIDAY INTO SATURDAY...KEEPING A SEASONABLY COOL AIRMASS IN
PLACE THROUGH THE START OF THE WEEKEND. HIGHS ON FRIDAY WILL BE IN
THE MID TO UPPER 60S AND WITH THE SURFACE HIGH OVERHEAD...LOWS
SATURDAY MORNING WILL DIP INTO THE LOW TO MID 40S. THE SURFACE HIGH
WILL BEGIN TO SHIFT OFF TO THE EAST THROUGH THE REMAINDER OF THE
WEEKEND AS MID LEVEL RIDGING BEGINS TO ESTABLISH ITSELF ALOFT. THIS
WILL RESULT IN A GRADUAL RETURN TO WARMER TEMPERATURES THROUGH THE
REST OF THE HOLIDAY WEEKEND. MODELS ARE STILL TRYING TO SUGGEST THE
POSSIBILITY OF SOME ENERGY DROPPING DOWN FROM THE NORTHWEST LATE IN
THE WEEKEND. HOWEVER...TIMING AND PLACEMENT ARE HIGHLY VARIABLE SO
WILL MAINTAIN A DRY FORECAST AT THIS POINT.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
MVFR CEILINGS WILL PERSIST FOR A FEW MORE HOURS UNTIL MIXING
RAISES CLOUD HEIGHTS AND VISIBILITIES LATER THIS AFTERNOON. WINDS
WILL GUST CLOSE TO 20 KNOTS DURING THIS TIME AS WELL. BR MAY FORM
AGAIN TONIGHT AT LUK AND ILN UNDER LIGHT WINDS AND A HUMID AIRMASS.
DAY MAY SEE A FEW SHOWERS TONIGHT IF ACTIVITY TO THE WEST HOLDS
TOGETHER AS INDICATED ON THE NAM AND RAP MODELS. CONVECTION MAY
DEVELOP AT ALL SITES ON TUESDAY AS FORCING INCREASES AHEAD OF A
FRONTAL ZONE...WITH WIND GUSTS OVER 20 KNOTS EXPECTED.
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM TUESDAY NIGHT THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...LATTO
NEAR TERM...LATTO
SHORT TERM...LATTO
LONG TERM...JGL
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
249 PM EDT MON MAY 20 2013
.SYNOPSIS...
UPPER TROUGH AXIS SLOWLY EXITS EAST TONIGHT. COLD FRONT APPROACHES
WEDNESDAY AND MOVES ACROSS THURSDAY. COOLER HIGH PRESSURE FRIDAY
AND THE WEEKEND.
&&
.NEAR TERM /THROUGH TUESDAY/...
RADAR IMAGERY AT 18Z SHOWING SHOWERS WITH A FEW EMBEDDED
THUNDERSTORMS MAINLY CONFINED TO THE EASTERN HIGHER TERRAIN AT THIS
POINT. EXPECT THIS PRECIP TO CONTINUE EASTWARD AS THE S/W TROUGH AND
ASSOC VORT MAX RESPONSIBLE FOR TODAY/S PRECIP CONTINUES EAST AS
WELL. LATEST SFC OBS AND RUC13 CONTINUE TO DEPICT SOME SFC
CONVERGENCE WITH WEAK TROUGH ACROSS THE FAR WESTERN ZONES THIS
AFTERNOON. BEST LLVL MOISTURE HAS PUSHED EASTWARD AND NEAR-TERM
CONVECTIVE MODELS DO NOT SHOW ANY REDEVELOPMENT ACROSS THE WEST.
WILL HOWEVER GO AHEAD AND CONTINUE A SLIGHT CHANCE FOR CONVECTION
OUT HERE WITH JUST A PINCH OF LLVL MOISTURE STILL NOTED ON POINT
SOUNDINGS AND PWATS UP AROUND 1.2-1.4 INCHES.
DURING THE OVERNIGHT HOURS TODAY/S S/W TROUGH AND VORT MAX CONTINUE
EASTWARD. PRECIP WILL HAVE ENDED FOR MOST IF NOT ALL LOCATIONS BTWN
00Z-03Z TUE. MOST LOCATIONS WILL REMAIN PRECIP-FREE OVERNIGHT BUT
LATEST NWP GUIDANCE DEPICTING A 2-3KFT LAYER OF CONVECTIVE MOISTURE
PUSHING INTO THE NORTHERN ZONES CENTERED AROUND 850MB AND AROUND 12Z
TUE. SIMULTANEOUSLY 850MB CONVERGENCE NOTED ACROSS THE I-79 CORRIDOR
AS WELL AND THUS WILL BRING IN SLIGHT CHANCE POPS WITH THUNDER WITH
THIS FEATURE. INHERITED MINS IN THE LOW/MID 60S MOST LOWLAND
LOCATIONS LOOK GOOD. WILL CONTINUE TO CARRY AT LEAST A SLIGHT CHANCE
OF SHOWERS/THUNDER MOST LOCATION DURING THE DAY...BUT THE BETTER
CHANCE OF THUNDERSTORMS ARRIVES SE OHIO ZONES BY AND AFTER 21Z AS
BETTER LLVL MOISTURE ARRIVES WITH DECENT SFC CONVERGENCE NOTED SAME
AREA. SHEAR IS WEAK AND THUS ORGANIZATION WILL BE AS WELL WITH
REGARD TO SEVERE POTENTIAL. BUT HEAVY DOWNPOURS WILL BE POSSIBLE AND
WITH SOME STRONG WINDS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
MAIN WEATHER MAKER THROUGH THE SHORT TERM WILL BE THE SURFACE COLD
FRONT PASSING WEDNESDAY...AND THEN THE LINGER UPPER LEVEL TROUGH.
FOR TUESDAY NIGHT...MAIN FOCUS IS TO THE WEST...SO DECREASED POPS
SOME...HOWEVER WITH LOTS OF MOISTURE STILL HANGING AROUND COULD NOT
GO DRY SO HAVE SLIGHT CHANCE TO CHANCE POPS FOR MUCH OF THE AREA
OVERNIGHT. COLD FRONT APPROACHES FROM THE WEST WEDNESDAY...WILL
LIKELY BE ONGOING CONVECTION/OUTFLOW BOUNDARIES TO OUR WEST
WEDNESDAY MORNING. WE SHOULD HAVE PLENTY OF INSTABILITY IN THE
WARM SECTOR AHEAD OF THE FRONT...NAM IS SHOWING 2000+ J/KG CAPE
ALONG THE OHIO RIVER AROUND NOON...WITH 30-40KTS BULK SHEER AND
PWATS AROUND 1.5 INCHES. SHOULD SEE A ROUND OF ORGANIZED
CONVECTION OUT AHEAD OF THE COLD FRONT MOVING FROM WEST TO EAST
ACROSS THE CWA. THE MOST LIKELY AREA OF CONCERN FOR STRONG TO
SEVERE STORMS CONTINUES TO BE ALONG AND EITHER SIDE OF THE OHIO
RIVER FROM SE OHIO INTO NORTH CENTRAL WEST VIRGINIA. WILL CONTINUE
HWO MENTION FOR DAMAGING WINDS AND HAIL POTENTIAL. THE ACTUAL COLD
FRONT WILL NOT PASS UNTIL THURSDAY...SO POPS CONTINUE THROUGH THE
SHORT TERM PERIOD.
WEDNESDAY WILL BE A WARM DAY...BUT WITH PLENTY OF CLOUDS SHOULD NOT
BE AS WARM AS TUESDAY. THURSDAY WILL BE ABOUT 10 DEGREES COOLER.
OVERNIGHT LOWS WILL BE MILD WITH LOTS OF CLOUDS AND MOISTURE.
BASED ON RECENT VERIFICATION STATS...BLENDED IN BIAS- CORRECTED
CONSENSUS GUIDANCE FOR BOTH HIGHS AND LOWS.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HAVE GENERALLY FOLLOWED WPC THINKING FOR THIS PORTION OF THE FORECAST.
COLD FRONT SHOULD BE LOCATED SOUTHEAST OF THE REGION AT THE
BEGINNING OF THE PERIOD...WITH HIGH PRESSURE BUILDING IN. CHANCE
OF SHOWERS AND STORMS WILL END FROM THE NORTHWEST THURSDAY NIGHT
INTO FRIDAY. HOWEVER...A MID-LEVEL DISTURBANCE MOVING SOUTHEAST
WILL INCREASE THE CHANCES FOR PRECIPITATION ON FRIDAY....MAINLY IN
THE MOUNTAINS AND ADJACENT COUNTIES.
HIGH PRESSURE WILL THEN BE IN CONTROL OF THE AREA INTO MONDAY.
HOWEVER...A WEAK MID-LEVEL DISTURBANCE WILL SLIDE SOUTHEAST SATURDAY
NIGHT INTO SUNDAY.
A WARM FRONT WILL DEVELOP AND APPROACH THE REGION ON MONDAY. ECMWF
SUGGESTS THERE WILL BE A CHANCE OF SHOWERS AND STORMS MONDAY
AFTERNOON...ESPECIALLY ACROSS THE SOUTH. BECAUSE OF UNCERTAINTY...HAVE
LEFT THESE CHANCES OUT OF THE FORECAST FOR NOW.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
MVFR TO LOW VFR CIGS ACROSS MUCH OF THE AREA CURRENTLY SHOULD
SCATTER WEST TO EAST AS THE AFTERNOON PROGRESSES AS THE LAST OF
THE PRECIP CONTINUES TO PUSH EASTWARD. VIS MAY ONCE AGAIN BECOME AN
ISSUE OVERNIGHT AND TOWARDS DAWN...PARTICULARLY AT LOCATIONS WHICH
RECEIVED RAINFALL TODAY SUCH AS CRW AND EKN. EARLY MORNING REDUCED
VIS/LOW STRATUS SHOULD ONCE AGAIN GIVE WAY TO VFR CONDITIONS BY
MID-MORNING. WINDS GENERALLY REMAIN LIGHT OUT OF THE S/SW THROUGH
THE VALID PERIOD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z TUESDAY...
FORECAST CONFIDENCE...MEDIUM.
ALTERNATE SCENARIOS: SOME UNCERTAINTY ON FOG DENSITY...LOW STRATUS...AND
AREAL COVERAGE OVERNIGHT AND EARLY MORNING TUESDAY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01
CRW CONSISTENCY M H H H H H H H H H H H
HTS CONSISTENCY M H H H H H H H H H H H
BKW CONSISTENCY M H H H H H H H H H H H
EKN CONSISTENCY H H H M H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY M M M H H H H H H H H H
AFTER 18Z TUESDAY...
IFR CONDITIONS POSSIBLE WEDNESDAY WITH SHOWERS AND THUNDERSTORMS.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...JSH/MZ/50
NEAR TERM...50
SHORT TERM...MZ
LONG TERM...JSH
AVIATION...50
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
142 PM EDT MON MAY 20 2013
.SYNOPSIS...
AN UPPER RIDGE ACROSS THE AREA TODAY WILL MOVE EAST TONIGHT. A
WEAK WARM FRONT WILL MOVE ACROSS THE REGION TODAY. AN AREA OF LOW
PRESSURE OVER THE NORTHERN PLAINS WILL SLOWLY PROGRESS EASTWARD
ACROSS THE GREAT LAKES REGION THROUGH MID WEEK. THE AIRMASS WILL
BECOME INCREASINGLY MOIST AND UNSTABLE AS THIS FEATURE APPROACHES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SCATTERED MORNING SHOWERS HAVE ALL ENDED AFTER ONE ROBUST
THUNDERSTORM DEVELOPED OVER NORTHERN LORAIN COUNTY/LAKE ERIE. SPC
RUC ANALSYS SHOWS 2000-2500 J/KG OF ML CAPE OVER NORTHERN OHIO
BUT GFS SOUNDINGS STILL REFLECT A CAP IN PLACE BETWEEN 850-700MB.
A SEVERE THUNDERSTORM WATCH HAS RECENTLY BEEN ISSUED ACROSS MOST
OF MICHIGAN WHERE SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FILL
IN DOWNWIND OF LAKE MICHIGAN WHERE BETTER LARGE SCALE FORCING IS
LOCATED. WE ARE CLOSER TO THE UPPER RIDGE AXIS AND HAVE AN
OVERALL LACK OF FORCING FOR ASCENT. IT WILL BE CLOSER TO EVENING
BEFORE THIS CONVECTION APPROACHES TOLEDO FROM THE NORTH. THE OTHER
AREA TO WATCH WILL BE NEAR THE LINGERING STRATUS WHERE
DIFFERENTIAL HEATING BOUNDARIES ARE DEVELOPING WITH TEMPERATURES
BENEATH THE CLOUD FIELD RUNNING AS MUCH AS 10 DEGREES COOLER. AT
THIS TIME NOT EXPECTING MUCH IN THE WAY OF THUNDERSTORMS FOR THE
AFTERNOON BUT WILL CONTINUE TO MONITOR. IF ANY THUNDERSTORMS
DEVELOP THEY WOULD HAVE THE POTENTIAL TO BE STRONG GIVEN THE
AVAILABLE INSTABILITY BUT HEAVY RAIN WOULD BE THE GREATEST THREAT
GIVEN THE SLOW MOVEMENT.
PREVIOUS DISCUSSION...TODAY IS A TOUGH FORECAST. THE HRRR AND
RUC/RAP MODELS HAVE BEEN FORECASTING A NARROW BAND OF
SHOWERS/THUNDERSTORMS TO DEVELOP OVER EASTERN INDIANA EARLY THIS
MORNING AND THEN MOVE EAST. AT 3 AM EDT THE ILN 88D WAS INDICATING
A FINE LINE OVER SE INDIANA. AS EACH HOUR HAS GONE ON THE MODELS
ARE DELAYING THE DEVELOPMENT AND INTENSITY OF THE PRECIPITATION.
NOW THEY DON`T HAVE ANY PRECIPITATION DEVELOPING ON THIS LINE
UNTIL AROUND 8 OR 9 AM MAINLY FROM CLE SOUTH. SOME OF THE RADAR
FORECAST OUTPUT FROM SPC STORM-SCALE ENSEMBLE OF OPPORTUNITY
MODELS ARE ALL OVER THE PLACE FOR TODAY...SOME WITH NO SHOWER OR
THUNDERSTORM DEVELOPMENT IN THE FORECAST AREA AND SOME WITH A
LITTLE DEVELOPMENT. THE 4KM WRF NMM MODEL HAS SOME ISOLATED
SHOWERS DEVELOPING. CONFIDENCE IS LOW IN THIS BECAUSE OF SO MUCH
RIDGING ALOFT...BUT WILL FORECAST A CHANCE OF SPRINKLES MAINLY
THIS AM AS THIS LINE MOVES THROUGH. WILL MONITOR THIS AND UPDATE
AS NEEDED.
ANY FOG THAT DEVELOPS THROUGH DAYBREAK SHOULD NOT BE SIGNIFICANT
ENOUGH TO BE MENTIONED IN THE ZONES/GRIDS.
NOT MUCH IN THE WAY OF CLOUDS ACROSS THE FORECAST AREA AT 4
AM...HOWEVER...THEY ARE EXPECTED TO DEVELOP THROUGH DAYBREAK.
PARTLY CLOUDY SHOULD HANDLE MOST OF TODAY.
OTHER THEN THIS NOT EXPECTING ANY SHOWERS AND THUNDERSTORMS TO
DEVELOP TODAY...THEY SHOULD HOLD OFF UNTIL AFTER 6 PM. NOT
EXPECTING MUCH OF A LAKE BREEZE AS THE GRADIENT WILL BE TOO
STRONG. ERIE MAY GET A LAKE BREEZE FOR A TIME THIS AFTERNOON. WENT
ON THE WARMER SIDE OF GUIDANCE FOR HIGHS BECAUSE OF AN INCREASING
SOUTHWEST FLOW AND WARMER AIR ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
THE UPPER LOW AND SURFACE LOW NOW OVER THE NORTHERN PLAINS WILL
MOVE SLOWLY EAST AND BE OVER THE FORECAST AREA THURSDAY AND
THURSDAY NIGHT. IN THE MEANTIME THE CHALLENGE IS FIGURING OUT THE
SHOWER AND THUNDERSTORM CHANCES.
FOR TONIGHT THE UPPER RIDGE MOVES EAST AND WITH SOME MOISTURE AND A
WEAK IMPULSE MOVING THROUGH KEPT CHANCE POPS MAINLY OVER THE
NORTHERN PORTION OF THE FORECAST AREA. THE RADAR FORECAST FROM THE
4KM WRF NMM 00Z MODEL SEEMS REASONABLE WITH SOME THUNDERSTORMS
BRUSHING THE NORTHERN PORTION OF THE FORECAST AREA.
FOR TUESDAY CHANCE POPS MOST AREAS BUT DID CONTINUE LIKELY POPS
EXTREME NORTHWEST OHIO. ON THE EDGE ABOUT THAT BASED ON THE LACK
OF MOISTURE ALOFT. THE AIRMASS IS UNSTABLE. FOR TUESDAY NIGHT
AGAIN...CHANCE POPS AS THE AIRMASS IS BECOMING MORE MOIST AND
CONTINUED UNSTABLE. FOR WEDNESDAY INTO THURSDAY WITH THE FRONT
GETTING CLOSE WEDNESDAY AND THEN SAGGING THROUGH ON THURSDAY
LIKELY POPS AT TIMES LOOKS VERY GOOD. AS WE GET CLOSER WE WILL BE
ABLE TO PUT MORE RESOLUTION INTO THE FORECAST.
USED A BLEND OF GUIDANCE AND THE PREVIOUS FORECAST FOR THE HIGHS AND
LOWS. THE HIGHS TUESDAY AND WEDNESDAY ARE TRICKY IF WE GET TOO MUCH
CONVECTION AND CLOUDS THIS WILL HAVE A TREMENDOUS IMPACT ON THE
TEMPERATURES.
RAINFALL AMOUNTS ARE EXPECTED TO BE LESS THAN INCH FOR THIS
WEEK...EXCEPT LOCALLY HIGHER AMOUNTS IN SOME THUNDERSTORMS.
THE AIRMASS FOR TONIGHT WILL BE SOMEWHAT DRY ALOFT AND THIS WILL
LEAD TO POSSIBLE SIGNIFICANT DOWNDRAFTS AS PER THE DELTA THETA E...WILL
MENTION THAT IN THE HAZARDOUS WEATHER OUTLOOK. WILL ALSO MENTION
RISK OF SEVERE TUESDAY THROUGH WEDNESDAY NIGHT ESPECIALLY.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
LITTLE CHANGE IN THE EXTENDED. BOTH GFS AND ECMWF MOVE HIGH
PRESSURE OVER THE AREA FRIDAY...WHICH LINGERS THROUGH THE WEEKEND.
EXTENDED LOOKS DRY WITH MORE SEASONAL TEMPS THROUGH THE WEEKEND.
&&
.AVIATION /17Z MONDAY THROUGH FRIDAY/...
AREA OF STRATUS OVER N-CENTRAL HAS LIFTED TO MVFR AND CONTINUES
TO ERODE FROM THE EDGES. EXPECT ALL AREAS TO BE VFR IN AN HOUR OR
TWO. STILL A LOT OF QUESTIONS ABOUT THUNDERSTORM ACTIVITY DURING
THE PERIOD. BEST GUESS RIGHT NOW IS THAT NW OH COULD SEE SOME
STORMS TOWARD EVENING. WILL GO WITH A MENTION OVER ABOUT THE WEST
HALF OF THE AREA. EASTERN AREAS SHOULD BE CAPPED AND WILL REMAIN
DRY THROUGH 18Z TUESDAY. ANOTHER ROUND OF STORMS COULD AFFECT
WESTERN AREAS BY MIDDAY TUESDAY. S TO SW FLOW WILL CONTINUE.
SPEEDS SHOULD BE 5 KNOTS OR LESS LATER TONIGHT WHICH SHOULD ALLOW
SOME PATCHY MVFR FOG TO DEVELOP BEFORE DAYBREAK. SPEEDS WILL
INCREASE ON TUESDAY MORNING WITH GUSTS TO 20 KNOTS LIKELY. KERI
ALREADLY HAS A LAKE BREEZE. DO NOT THINK IT WILL REACH KCLE TODAY.
.OUTLOOK...NON VFR PROBABLE IN SHOWERS/THUNDERSTORMS OVERNIGHT THROUGH
THURSDAY.
&&
.MARINE...
PREDOMINATELY A SOUTH TO SOUTHEAST FLOW TODAY ALTHOUGH COULD SEE A
WEAK LAKE BREEZE EAST HALF FOR A FEW HOURS. EXPECT SOUTHWEST FLOW
TO DEVELOP TOMORROW AHEAD OF NEXT SYSTEM. MODELS IN GOOD AGREEMENT
PUSHING THE NEXT FRONT THROUGH ON THURSDAY. WITH NORTH TO NORTHEAST
FLOW DEVELOPING BEHIND THE SYSTEM WILL APPROACH SMALL CRAFT ADVISORY
CRITERIA.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KIELTYKA
NEAR TERM...KEC/KIELTYKA
SHORT TERM...KIELTYKA
LONG TERM...DJB
AVIATION...KUBINA
MARINE...DJB
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
141 PM EDT MON MAY 20 2013
.SYNOPSIS...
A MID LEVEL RIDGE WILL BUILD ACROSS THE REGION TODAY. THE RIDGE
WILL MOVE EAST TONIGHT AS A LARGE UPPER LEVEL LOW OVER THE
NORTHERN PLAINS BEGINS TO MAKE A SLOW PROGRESSION TO THE EAST.
THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL INCREASE TUESDAY
INTO WEDNESDAY AS THE LOW CONTINUES TOWARD THE GREAT LAKES. A COLD
FRONT WILL EVENTUALLY PUSH THROUGH OUR AREA WEDNESDAY INTO WEDNESDAY
NIGHT. ABOVE NORMAL TEMPERATURES ALONG WITH A HUMID AIRMASS WILL
REMAIN IN PLACE UNTIL AFTER FRONTAL PASSAGE.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HAVE UPDATED POPS TO LIKELY EAST OF COLUMBUS WHERE LINE OF
THUNDERSTORMS DEVELOPED ALONG A WEAK NORTH-SOUTH ORIENTED
BOUNDARY.
FOR THIS AFTERNOON...A VERY WARM AND HUMID AIRMASS WILL PREVAIL.
WITH THE RIDGE IN PLACE...CONVECTION SHOULD BE HELD AT BAY.
HOWEVER...WITH MODERATE TO STRONG INSTABILITY ALONG WITH A VERY
WEAK CAP...IT IS NOT OUT OF THE QUESTION THAT AN ISOLATED SHOWER
OR STORM COULD POP. GIVEN THAT THIS CHANCE IS ABOUT 10
PERCENT...HAVE LEFT THE FORECAST DRY FOR THE AFTERNOON HOURS.
HIGHS TODAY WILL WARM INTO THE UPPER 80S WITH A FEW SPOTS POSSIBLY
REACHING 90 DEGREES BEFORE THE AFTERNOON IS THROUGH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
HAVE USED A BLEND OF THE GFS...CMC AND ECMWF FOR THE SHORT TERM
FORECAST.
MID LVL RIDGE WILL MOVE EAST TONIGHT AS A LARGE UPR LVL LOW OVER
THE NORTHERN PLAINS PUSHES SLOWLY EAST TOWARD THE GREAT LAKES.
CHANCES OF SHOWERS AND THUNDERSTORMS WILL ENCROACH THE WESTERN
ZONES AS MODELS SUGGEST THAT A WEAKENING COMPLEX APPROACHES THE
REGION.
ON TUESDAY...VERY WARM AND HUMID CONDITIONS WILL CONTINUE. TIMING
AND COVERAGE OF CONVECTION WILL BE DEPENDENT ON PREVIOUS FEATURE
MOVING INTO THE AREA WHICH IS STILL SKETCHY AT THIS TIME. AS A
RESULT...HAVE GONE WITH CHANCE POPS. GIVEN INCREASING SHEAR AND
MODERATE TO STRONG INSTABILITY...A FEW SEVERE STORMS WILL BE
POSSIBLE.
FOR TUESDAY NIGHT...THE THREAT FOR SHOWERS/STORMS WILL
CONTINUE...BUT MODELS SUGGEST THAT WE MAY BE IN A RELATIVE LULL
BEFORE A MORE BONAFIDE S/WV AND ASSOCIATED COLD FRONT AFFECT THE
REGION ON WEDNESDAY.
FOR WEDNESDAY INTO WEDNESDAY NIGHT...UPR LVL LOW WILL DROP
SOUTHEAST INTO THE GREAT LAKES. AS MENTIONED...A MORE BONAFIDE
S/WV IS EXPECTED TO ROTATE NE ACROSS THE AREA ALONG WITH A SFC
COLD FRONT. ALTHOUGH SHEAR WILL BE MODERATE...INSTABILITY WILL BE
A LITTLE LESS THAN TUESDAY GIVEN CLOUDS AND SLIGHTLY COOLER
TEMPERATURES. EVEN SO...CAN NOT RULE OUT A FEW SEVERE STORMS
DURING THE AFTERNOON INTO THE EVENING HOURS.
ON THURSDAY...UPR LVL LOW WILL DROP SE INTO OUR AREA. MODELS
SUGGEST THAT A SECONDARY COLD FRONT/TROUGH AXIS WILL APPROACH THE
REGION FROM THE NORTHWEST...KEEPING THE THREAT FOR SHOWERS AND
ISOLATED STORMS. TEMPERATURES WILL BE COOLER GIVEN CLOUDS AND CAA
WITH HIGHS RANGING FROM THE UPPER 60S NW TO THE MID 70S SOUTHEAST.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS THE SECONDARY FRONT/TROUGH AXIS SHIFTS SOUTH THURSDAY NIGHT...
PCPN SHOULD TAPER OFF FROM NORTH TO SOUTH.
HIGH PRESSURE AND A COOLER AIRMASS WILL BUILD DOWN FROM THE NORTH
THROUGH THE DAY ON FRIDAY. THIS WILL LEAD TO SLIGHTLY BELOW NORMAL
TEMPERATURES WITH HIGHS ON FRIDAY IN THE UPPER 60S TO LOWER 70S. THE
AIRMASS WILL THEN SLOWLY MODERATE THROUGH THE WEEKEND AS MID LEVEL
RIDGING BEGINS TO WORK IN FROM THE WEST. BY SUNDAY...TEMPERATURES
WILL BE BACK TO NEAR NORMAL WITH HIGHS PUSHING BACK TOWARD THE MID
70S. WILL MAINTAIN A DRY FORECAST THROUGH THE WEEKEND AT THIS POINT
BUT THE 12Z ECMWF AND TO A LESSER EXTENT THE 12Z GFS ARE HINTING AT
THE POSSIBILITY OF SOME SHORT WAVE ENERGY DROPPING DOWN IN NORTHWEST
FLOW LATE IN THE PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
MVFR CEILINGS WILL PERSIST FOR A FEW MORE HOURS UNTIL MIXING
RAISES CLOUD HEIGHTS AND VISIBILITIES LATER THIS AFTERNOON. WINDS
WILL GUST CLOSE TO 20 KNOTS DURING THIS TIME AS WELL. BR MAY FORM
AGAIN TONIGHT AT LUK AND ILN UNDER LIGHT WINDS AND A HUMID AIRMASS.
DAY MAY SEE A FEW SHOWERS TONIGHT IF ACTIVITY TO THE WEST HOLDS
TOGETHER AS INDICATED ON THE NAM AND RAP MODELS. CONVECTION MAY
DEVELOP AT ALL SITES ON TUESDAY AS FORCING INCREASES AHEAD OF A
FRONTAL ZONE...WITH WIND GUSTS OVER 20 KNOTS EXPECTED.
OUTLOOK...THUNDERSTORMS WILL BE POSSIBLE FROM TUESDAY NIGHT THROUGH
THURSDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...CONIGLIO/HICKMAN
SHORT TERM...HICKMAN
LONG TERM...HICKMAN/JGL
AVIATION...CONIGLIO
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
309 PM CDT MON MAY 20 2013
.SHORT TERM...THROUGH TUESDAY
AXIS OF SHOWERS HAS SHIFTED INTO THE EASTERN CWA THIS
AFTERNOON...WITH A BREAK FOR COUNTIES WEST OF ABERDEEN. THIS
BREAK WILL BE SHORT LIVED AS RADARS UPSTREAM IN NORTH DAKOTA ARE
QUITE ACTIVE...WITH WIDESPREAD LIGHT/MODERATE RAINFALL. HRRR AND
RUC GUIDANCE PIVOTS THIS MOISTURE BACK OVER THE CWA THIS EVENING
AND PERSISTS WELL INTO TUESDAY. MOST OF THE AREA HAS BEEN ABLE TO
HANDLE THE MOISTURE THUS FAR...WITH A FEW SPOTS REPORTING RISING
WATER IN DITCHES/CREEKS BUT NOT MUCH IMPACT OTHERWISE. SREF
PROBABILITIES FOR GREATER THEN A QUARTER INCH ARE HIGHEST ACROSS
OUR NORTHER MISSOURI COUNTIES...AN AREA THAT HAS NOT RECEIVED MUCH
DROUGHT RELIEF THIS SPRING...AND THUS THINK AREA CAN HANDLE THE
ADDITIONAL 1/2 INCH RAIN. SOILS FARTHER SOUTH AND EAST MAY BE LESS
FORGIVING AND WILL NEED TO BE MONITORED THIS EVENING/OVERNIGHT FOR
WATER ISSUES.
AS THE STACKED LOW CONTINUES TO DRIFT EAST TUESDAY...LIFT WEAKENS
WITH SOME DRIER AIR ENTRAINMENT RESULTING IN LOWER PROBABILITY FOR
PRECIPITATION AND QPF. TEMPERATURES THIS PERIOD WILL REMAIN BELOW
NORMAL AND CHANGE LITTLE THANKS TO CLOUD COVER.
.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
AS THE PERIOD OPENS...A DECAYING UPPER LOW CIRCULATION OVER THE
REGION WILL BE SLOWLY DRIFTING SOUTHEAST OUT OF THE AREA.
CONTINUED WRAP-AROUND MOISTURE COMBINED WITH SOME WEAK TROWALESQUE
FORCING/LIFT WILL KEEP POPS/RAIN SHOWERS MENTION GOING TUESDAY
NIGHT INTO WEDNESDAY AS THIS LOW PULLS AWAY FROM THE REGION.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT SHOULD BE DRY FORECAST
PERIODS WHILE A TRANSIENT HIGH-AMPLITUDE LONGWAVE HIGH PRESSURE
RIDGE WORKS THROUGH THE REGION.
BY FRIDAY...LOW LEVEL RETURN FLOW IS IN FULL SWING AND POPS FOR
SHOWERS AND THUNDERSTORMS MAKE THEIR RETURN TO THE FORECAST AS MID
AND UPPER LEVEL FLOW TAKES ON A RATHER PROLONGED PERIOD OF SWRLY
FLOW...THAT IS CURRENTLY PROGGED BY THE GFS AND ECMWF TO LAST
RIGHT INTO MONDAY.
THE COOLEST TEMPS DURING THE PERIOD LOOK TO BE TUESDAY NIGHT AND
WEDNESDAY BEFORE THE WARMING TREND ENSUES. BY THE
WEEKEND...TEMPERATURES SHOULD BE MUCH CLOSER TO CLIMO NORMAL.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
AREA OF RAIN PIVOTING THROUGH KABR AND KPIR...EXITING KMBG...WITH
A SECOND AREA OF SHOWERS OVER/NORTH OF KATY. MOST OF THE RAIN IS
LIGHT WITH VFR VISBY AND MVFR CIGS...THOUGH HEAVIER POCKETS ARE
RESULTING IN IFR CIGS. THIS LINE IS CLEARING KMBG SO EXPECT
IMPROVING CONDITIONS...HOWEVER ANOTHER BAND OF MODERATE RAIN IS
SET TO PIVOT DOWN OUT OF NORTH DAKOTA THIS EVENING. FOR
KATY...BEING IN A WARMER/UNSTABLE AIRMASS...A FEW WEAK
THUNDERSTORMS COULD POP FOR A FEW HOURS THIS AFTERNOON.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
SHORT TERM...CONNELLY
LONG TERM...DORN
AVIATION...CONNELLY
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
603 PM CDT MON MAY 20 2013
.UPDATE...FOR AVIATION.
&&
.AVIATION...
00Z TAFS...UPPER LEVEL RIDGE WILL CONTINUE TO BE THE MAIN
INFLUENCE WITH FAIR WX THROUGH THIS EVENING. SOME MVFR BR OR
PERHAPS PATCHY STRATUS IS POSSIBLE TOWARD DAYBREAK. S WINDS WILL
BECOME SOMEWHAT GUSTY ON TUESDAY...TO 20KT AT TIMES...ESPECIALLY
FOR CKV. THE RIDGE WILL BEGIN TO MOVE EAST WITH AN APPROACHING
DISTURBANCE BRINGING A CHANCE FOR TSRA BY THE END OF THE PERIOD.
COVERAGE WILL BE GENERALLY ISOLD...BUT COVERAGE WILL BE INCREASING
FROM THE WEST...SO INCLUDING A VCTS FOR CKV AFTER 21Z.
13
&&
.PREV DISCUSSION... /ISSUED 324 PM CDT MON MAY 20 2013/
AFTERNOON CU DEVELOPMENT IS WIDESPREAD ACROSS THE MID STATE THIS
AFTERNOON AS DEWPOINTS HAVE CONTINUED TO RISE. MID LEVEL CAP IS
RATHER STRONG ACCORDING TO THE 12Z SOUNDING FROM THIS MORNING. THE
HIGHER DEWPOINTS HAVE ACTED TO LOWER CONVECTIVE TEMPS BUT CURRENT
TEMPS ARE STRUGGLING TO RISE GIVEN THE EXTRA CLOUD COVER.
FOR TONIGHT`S FORECAST...WILL INCLUDE A 20 POP BUT ONLY FOR THE
NW. THIS IS IN LINE WITH THE HRRR REFLECTIVITY FCST WHICH SHOWS
LITTLE IF ANY DEVELOPMENT. OVERALL...IT JUST APPEARS THAT THERE IS
TOO MUCH VERTICAL DRYNESS IN PLACE.
A SLIGHT CHANCE OF SHOWERS AND TSTMS WILL BE IN THE FCST AGAIN FOR
TUESDAY. MOISTURE LEVELS SHOULD BE HIGHER AND WE DO SEE MORE 18Z CAP
EROSION WITH THE GFS MODEL. THE INCREASE IN MOISTURE WILL BE AIDED
BY AN APPROACHING FRONTAL BOUNDARY WHICH WILL IMPACT THE AREA LATE
TUESDAY NIGHT AND INTO WEDNESDAY. AT THAT TIME...A SLIGHT RISK OF
SEVERE WEATHER IS IN THE FCST FOR OUR NW COUNTIES. BEST OMEGA
FORCING APPEARS TO BE AROUND 06Z WEDNESDAY ACROSS WESTERN TN.
BUT...THERE COULD BE A FEW STRONGER CELLS OVER THAT SAME AREA
EARLIER ON TUES AFTERNOON. STORM MOTION SHOULD RUN FROM SW TO NE.
SHOWERS AND TSTMS TO PERSIST INTO WEDNESDAY. ITS IMPORTANT TO NOTE
HOWEVER THAT OVERALL POPS WITH THIS SYSTEM ARE NOT DRASTICALLY HIGH.
IN FACT...MODELS NOT LEANING TOWARD DEEP MOISTURE WITH A WIDESPREAD
AREA OF RAIN OCCURRING. NEVERTHELESS...POPS IN THE 40-60 PERCENT
RANGE WILL BE INCLUDED FOR TUESDAY NT INTO WEDNESDAY. AFTER A FEW
LINGERING SHOWERS ON THURSDAY ACROSS THE PLATEAU...CLEARING WILL
OCCUR WITH DRIER AIR MOVING IN.
FOR THE NEAR TERM TEMPS...WILL AGAIN UNDERCUT THE HIGH TEMPS FOR
TUESDAY AND WEDNESDAY. OVERNIGHT LOWS FROM THE GUIDANCE APPEARS
REASONABLE.
IN THE EXT FCST...NICE LATE MAY CONDITIONS ARE ON TAP FOLLOWING THE
FROPA WHICH WAS MENTIONED IN THE SHORT TERM TIME FRAME.
THUS...SUNSHINE TO RETURN IN EARNEST FOR FRIDAY AND INTO THE
WEEKEND. THERMAL TROUGHING WILL BE SLOW TO GIVE WAY AND
THUS...MOSTLY SUNNY SKIES WITH BELOW NORMAL TEMPS AND LOWER
HUMIDITY LEVELS WILL PREVAIL THU THROUGH SAT. SUNDAY AND MONDAY...UPPER
RIDGING AND HEIGHT RISES WILL BE ON TAP. THIS WILL EQUATE TO HIGH
TEMPS BACK UP INTO THE 80S. BUT...STILL NOT SEEING ANY APPRECIABLE
PRECIP CHANCES THROUGH MONDAY.
21
&&
.OHX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
324 PM CDT MON MAY 20 2013
DISCUSSION...
AFTERNOON CU DEVELOPMENT IS WIDESPREAD ACROSS THE MID STATE THIS
AFTERNOON AS DEWPOINTS HAVE CONTINUED TO RISE. MID LEVEL CAP IS
RATHER STRONG ACCORDING TO THE 12Z SOUNDING FROM THIS MORNING. THE
HIGHER DEWPOINTS HAVE ACTED TO LOWER CONVECTIVE TEMPS BUT CURRENT
TEMPS ARE STRUGGLING TO RISE GIVEN THE EXTRA CLOUD COVER.
FOR TONIGHT`S FORECAST...WILL INCLUDE A 20 POP BUT ONLY FOR THE
NW. THIS IS IN LINE WITH THE HRRR REFLECTIVITY FCST WHICH SHOWS
LITTLE IF ANY DEVELOPMENT. OVERALL...IT JUST APPEARS THAT THERE IS
TOO MUCH VERTICAL DRYNESS IN PLACE.
A SLIGHT CHANCE OF SHOWERS AND TSTMS WILL BE IN THE FCST AGAIN FOR
TUESDAY. MOISTURE LEVELS SHOULD BE HIGHER AND WE DO SEE MORE 18Z CAP
EROSION WITH THE GFS MODEL. THE INCREASE IN MOISTURE WILL BE AIDED
BY AN APPROACHING FRONTAL BOUNDARY WHICH WILL IMPACT THE AREA LATE
TUESDAY NIGHT AND INTO WEDNESDAY. AT THAT TIME...A SLIGHT RISK OF
SEVERE WEATHER IS IN THE FCST FOR OUR NW COUNTIES. BEST OMEGA
FORCING APPEARS TO BE AROUND 06Z WEDNESDAY ACROSS WESTERN TN.
BUT...THERE COULD BE A FEW STRONGER CELLS OVER THAT SAME AREA
EARLIER ON TUES AFTERNOON. STORM MOTION SHOULD RUN FROM SW TO NE.
SHOWERS AND TSTMS TO PERSIST INTO WEDNESDAY. ITS IMPORTANT TO NOTE
HOWEVER THAT OVERALL POPS WITH THIS SYSTEM ARE NOT DRASTICALLY HIGH.
IN FACT...MODELS NOT LEANING TOWARD DEEP MOISTURE WITH A WIDESPREAD
AREA OF RAIN OCCURRING. NEVERTHELESS...POPS IN THE 40-60 PERCENT
RANGE WILL BE INCLUDED FOR TUESDAY NT INTO WEDNESDAY. AFTER A FEW
LINGERING SHOWERS ON THURSDAY ACROSS THE PLATEAU...CLEARING WILL
OCCUR WITH DRIER AIR MOVING IN.
FOR THE NEAR TERM TEMPS...WILL AGAIN UNDERCUT THE HIGH TEMPS FOR
TUESDAY AND WEDNESDAY. OVERNIGHT LOWS FROM THE GUIDANCE APPEARS
REASONABLE.
IN THE EXT FCST...NICE LATE MAY CONDITIONS ARE ON TAP FOLLOWING THE
FROPA WHICH WAS MENTIONED IN THE SHORT TERM TIME FRAME.
THUS...SUNSHINE TO RETURN IN EARNEST FOR FRIDAY AND INTO THE
WEEKEND. THERMAL TROUGHING WILL BE SLOW TO GIVE WAY AND
THUS...MOSTLY SUNNY SKIES WITH BELOW NORMAL TEMPS AND LOWER
HUMIDITY LEVELS WILL PREVAIL THU THROUGH SAT. SUNDAY AND MONDAY...UPPER
RIDGING AND HEIGHT RISES WILL BE ON TAP. THIS WILL EQUATE TO HIGH
TEMPS BACK UP INTO THE 80S. BUT...STILL NOT SEEING ANY APPRECIABLE
PRECIP CHANCES THROUGH MONDAY.
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 68 89 67 82 / 05 20 50 70
CLARKSVILLE 68 87 65 82 / 10 30 60 50
CROSSVILLE 64 85 65 77 / 10 30 40 70
COLUMBIA 68 89 67 82 / 05 20 40 60
LAWRENCEBURG 66 88 67 82 / 05 20 40 60
WAVERLY 68 87 66 82 / 10 30 60 50
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
21
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
331 PM CDT MON MAY 20 2013
.VERY SHORT TERM...TONIGHT AND TUESDAY. FORECAST CONFIDENCE...LOW
TO MEDIUM.
BIGGEST CONCERN INTO TONIGHT IS TIMING AND STRENGTH OF EXPECTED
THUNDERSTORMS. SPC IS MAINTAINING A SLIGHT RISK FOR SEVERE STORMS
ACROSS THE FORECAST AREA. LATEST NAM AND RAP SOUNDINGS AGREE THAT
THE ENVIRONMENT STILL LOOKS FAVORABLE FOR STRONG TO SEVERE STORMS.
WITH THE CONTINUED SUNSHINE...SHOULD SEE SFC BASED CAPE VALUES GET
IN THE 1000-1500 J/KG RANGE BY LATE AFTERNOON OR EARLY EVENING.
ADDITIONALLY...PLENTY OF 0-6 KM BULK SHEAR...GENERALLY 35-45 KT.
PLENTY OF MOISTURE AS WELL...WITH PRECIPITABLE WATER VALUES
INCREASING TO AROUND 1.25 INCHES THIS EVENING...ABOVE CLIMATOLOGICAL
NORMALS.
WITH A DECENT ENVIRONMENTAL SETUP...WILL JUST BE WAITING FOR THE
TRIGGER. TIMING OF UPSTREAM SHORTWAVE ALONG WITH LATEST HRRR AND
LOCAL WRF4L MODEL INDICATE THAT CONVECTION MAY HOLD OFF ACROSS
SOUTHERN WISCONSIN UNTIL THE MID-EVENING HOURS. ONE THING TO NOTE IS
THAT THE LAST FEW RUNS OF MESOSCALE MODELS HAVE BEEN ALL OVER THE
PLACE WITH CONVECTIVE SOLUTIONS FOR THIS EVENING...SO NOT A TON OF
CERTAINTY AT THIS POINT.
LOW PRESSURE REMAINING TO THE WEST WILL KEEP SOUTHERN WISCONSIN IN A
WARM AN UNSTABLE ENVIRONMENT THROUGH TUESDAY...THUS CHANCE FOR
THUNDERSTORMS WILL CONTINUE. SIMILAR TO TODAY...NOT A LOT OF
CERTAINTY IN TIMING AND PLACEMENT OF DEVELOPMENT. ANY STORMS THAT DO
DEVELOP TOMORROW WILL HAVE THE CHANCE TO BECOME STRONG TO
SEVERE...WITH SPC MAINTAINING A SLIGHT RISK FOR SEVERE STORMS.
.SHORT TERM...TUESDAY NIGHT THROUGH THURSDAY. FORECAST CONFIDENCE
MEDIUM.
CLOSED LOW FINALLY BEGINS TO MOVE AS IT OPENS AND BECOMES PHASED
WITH TROUGH DROPPING TOWARD THE NORTHERN GREAT LAKES AS IT ROTATES
AROUND POLAR VORTEX JUST EAST OF HUDSON BAY.
ONE MORE ROUND OF CONVECTION EXPECTED WITH 500 MB SHORT WAVE TUE
NGT/WED AM WITH LAYER Q-VECTOR MAXIMA AND FRONTOGENETIC FORCING
INDICATING BEST CHANCES MAINLY AFTER 06Z WED...WITH MAX
FRONTOGENETIC FORCING OVER THE CWA AT 12Z WED. FORCING LIFTS
THRU...STALLS AND THEN DROPS BACK ACROSS REGION AS SYSTEM OPENS AND
MOVES RIGHT ACROSS THE STATE...WITH MID-LEVEL TROF AXIS SOUTH OF CWA
AROUND 18Z THURSDAY. THE SLIGHTLY DIFFERING SOLUTIONS TO TIMING AND
STRUCTURE AMONG THE MODELS LEADS TO VARIOUS AMOUNTS OF QPF. WENT
WITH BLENDED QPF AMOUNTS WITH A LEAN TOWARD THE HIGHER NUMBERS...BUT
IF CONVERGENCE BAND SETS UP RIGHT OVER THE REGION...THEN AMOUNTS
COULD GO EVEN HIGHER AND AREAL/RIVER FLOODING COULD COME INTO PLAY.
NOT ENOUGH CONFIDENCE TO RE-ISSUE AN EFS AT THIS TIME BUT WILL NEED
TO BE WATCHED.
TEMPERATURES DO NOT FALL MUCH TUESDAY NIGHT WITH CLOUDS AND THE AREA
STAYING ROUGHLY TO THE WARM SIDE OF THE LOW AS IT MOVES THROUGH SO
FOLLOWED LOWS CLOSER TO THE WARMER GUIDANCE NUMBERS. HIGHS WEDNESDAY
WILL BE AROUND MID DAY...THEN COOL WITH WINDS TURNING NORTHERLY AS
SURFACE LOW/TROUGH SLIDES BY...THOUGH LINGERING TROUGHINESS WILL
PREVENT MUCH OF A GRADIENT UNTIL CLOSER TO THURSDAY MORNING. HIGHS
THURSDAY WILL ONLY GET TO THE MID 60S WELL INLAND...WITH 50S ALONG
THE LAKE.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY. FORECAST CONFIDENCE
AMOUNT OF COOLING VARIES WITH DEPTH OF EVOLVING 500 MB TROUGH OVER
EASTERN CANADA. OMEGA BLOCK SETS UP WITH AN AMPLIFYING RIDGE OVER
THE PLAINS BETWEEN EASTERN CANADA VORTEX AND CLOSED LOW OVER THE
PACIFIC NW...WITH THE FORECAST AREA REMAINING UNDER THE NW FLOW OF
THE EASTERN TROUGH THROUGH SATURDAY. LESS AMPLIFIED ECMWF ALLOWS
WARM AIR ADVECTION PRECIPITATION AHEAD OF SHORT WAVE UNDERCUTTING
THE RIDGE AND ASSOCIATED INVERTED SURFACE TROUGH CROSSING THE REGION
FRIDAY NIGHT AND SATURDAY. MORE DOMINANT SURFACE HIGH PRESSURE WITH
MORE AMPLIFIED GFS/GEM HOLDS PCPN CHANCES OFF UNTIL SATURDAY
AFTERNOON/SATURDAY NIGHT ON THE GEM...AND NOT UNTIL SUNDAY WITH THE
GFS. WHILE THE CONSENSUS BLEND HAS PRECIPITATION CHANCES THROUGH THE
HOLIDAY WEEKEND DUE TO THE TIMING SPREAD IN THE MODELS...THERE WILL
BE DRY PERIODS. TEMPERATURES WILL BE BELOW NORMAL...WITH HIGHS
TRYING TO GET BACK INTO THE LOWER 70S MONDAY AWAY FROM THE LAKE.
&&
.AVIATION/00Z TAFS/...
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH TUESDAY...THOUGH
LOWER CIGS/VSBYS POSSIBLE IN ANY THUNDERSTORMS. BIG ISSUE THROUGH
TOMORROW REMAINS TIMING ROUNDS OF THUNDERSTORMS. LOOKS QUIET THROUGH
LATE AFTERNOON...WITH LATEST MESOSCALE MODELS SUGGESTING DEVELOPMENT
POSSIBLE THIS EVENING AND INTO THE NIGHT. TOOK A STAB AT BEST CHANCE
FOR STORMS IN THE TAFS...THOUGH STILL HAD TO KEEP IT FAIRLY GENERAL
DUE TO A GOOD AMOUNT OF UNCERTAINTY. CHANCE FOR STORMS WILL CONTINUE
TUESDAY.
&&
.MARINE...
WILL LIKELY SEE GUSTS TO 25 KNOTS FROM NORTH POINT LIGHT SOUTHWARD
INTO EARLY EVENING...UNTIL DAYTIME HEATING/MIXING DECREASES. WILL
THUS KEEP THE SMALL CRAFT ADVISORY GOING UNTIL 01Z. FARTHER
NORTH...COULD SEE A FEW GUSTS TO 25 KNOTS...BUT OVERALL GRADIENT IS
A BIT WEAKER. PLUS...WINDS CONTINUE TO HAVE AN ONSHORE COMPONENT AT
TIMES ACROSS THE NORTH...WHICH SHOULD LIMIT GUST POTENTIAL DUE TO
THE STABLE AIRMASS OVER THE LAKE.
WINDS WILL MAINLY BE SOUTH TO SOUTHWEST THROUGH TUESDAY...SO OVERALL
FOG POTENTIAL WILL BE LIMITED. COULD SEE SOME FOG FOR A TIME IF
WINDS ARE SOUTHEAST LONGER THAN EXPECTED.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR LMZ645-646.
&&
$$
TONIGHT/TUESDAY AND AVIATION/MARINE...DDV
TUESDAY NIGHT THROUGH MONDAY...REM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1235 PM CDT MON MAY 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT MON MAY 20 2013
MAIN FORECAST CONCERN IS ON SEVERE WEATHER AND FLOODING POTENTIAL
TODAY.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED AN UPPER LOW OVER SOUTH DAKOTA AND NEBRASKA WITH RIDGING
AHEAD OF IT OVER MICHIGAN. THE UPPER LOW WAS MOSTLY CUT OFF WITH
RIDGING TO ITS NORTH OVER SOUTH CENTRAL CANADA. 500MB STANDARD
DEVIATIONS WERE 1-1.5 BELOW NORMAL WITH THE UPPER LOW. NUMEROUS
SHORTWAVES WERE EJECTING IN SOUTHWEST FLOW AHEAD OF THE UPPER
LOW...SOME OF WHICH ARE CONVECTIVELY PRODUCED. ONE FOR EXAMPLE WAS
LIFTING THROUGH NORTHWEST WISCONSIN WHICH BROUGHT RAIN TO MUCH OF
THE AREA DURING THE NIGHTTIME HOURS. RAP DATA ALSO SHOWED A LOW
LEVEL MOISTURE TRANSPORT ZONE WITH THIS MCV. FARTHER SOUTH...ANOTHER
LOW LEVEL MOISTURE TRANSPORT ZONE WAS NOTED IN SOUTHERN MISSOURI...
POINTING INTO SOUTHERN ILLINOIS. COMBINATION OF SUBSIDENCE IN THE
WAKE OF THE MCV AND SPLIT IN MOISTURE TRANSPORT HAS ALLOWED THE
PRECIPITATION TO DIMINISH SOUTH OF HWY 29. PLENTIFUL MOISTURE COMING
UP AHEAD OF THE UPPER LOW WITH PRECIPITABLE WATER VALUES OF 1.2-1.5
INCHES FROM EASTERN OK INTO SOUTEHRN WI. THERE WAS A MINIMA OF
PRECIPITABLE WATER FROM WESTERN KS INTO MUCH OF IA...THOUGH....
ASSOCIATED WITH A DRY SLOT SOUTH OF THE UPPER LOW. AT THE
SURFACE...LOW PRESSURE WAS SITUATED UNDER THE UPPER LOW WITH A WARM
FRONT EXTENDING EAST TO EAU CLAIRE WI. RAP 850MB TEMPS WERE IN THE
14-18C RANGE SOUTH OF THE FRONT IN THE FORECAST AREA.
MODELS ARE IN GOOD AGREEMENT OF KEEPING THE UPPER LOW NEARLY
STATIONARY OVER SOUTH DAKOTA. DESPITE ITS STATIONARY MOVEMENT...THE
WEATHER WILL BE QUITE A BIT DIFFERENT COMPARED TO YESTERDAY.
PRIMARILY THIS IS DUE TO THE UPPER FLOW AHEAD OF THE UPPER LOW
PROGGED MORE SOUTHWESTERLY VERSUS SOUTHERLY. ADDITIONALLY...THE
PLUME OF HIGHER PRECIPITABLE WATER IS PROGGED TO SLOWLY SHIFT EAST
THANKS TO THE UPPER LOW.
MOST OF THE FORECAST AREA IS INDICATED TO STAY IN THE WARM SECTOR
THROUGH TONIGHT...ALONG WITH EXISTING IN THAT SOUTHWEST FLOW FOR
SHORTWAVES TO COME THROUGH...BOTH FAVORABLE FOR THUNDERSTORM
DEVELOPMENT. HOWEVER...ONE QUESTION MARK IS MOISTURE. BASED ON A
AMDAR SOUNDING OUT OF OMAHA AT 04Z...THE 850MB DEWPOINTS FROM THE
20.00Z NAM WERE 6-7C TOO HIGH...THUS THE NAM BUILDS A LOT OF CAPE
QUICKLY THIS MORNING. THE RAP IS MUCH MORE SUBDUED HAVING THE AREA
ENCOMPASSED BY THE DRY AIR...ESPECIALLY WHEN LOOKING AT MLCAPE.
THINKING THE RAP IDEA IS MUCH MORE REPRESENTATIVE AND HAVE KEPT THE
AREA DRY THROUGH EARLY AFTERNOON. EVENTUALLY...THE RAP DOES CATCH UP
WITH THE CAPE LATE IN THE AFTERNOON THANKS TO EVAPOTRANSPORATION OF
MOIST SOILS. IN FACT...THE RAP SHOWS A DEFINITIVE DRY LINE IN THE
WARM SECTOR FORMING NEAR I-35 IN THE AFTERNOON. THIS DRY LINE SHOULD
SERVE AS A TRIGGER FOR CONVECTIVE DEVELOPMENT...ESPECIALLY IN
SOUTHEAST MN AND NORTHEAST IA. MAJORITY OF MODELS...INCLUDING HI
RESOLUTION ONES...SHOW THIS SCENARIO...WITH THE THUNDERSTORMS THEN
PROPAGATING NORTHEAST THROUGH THE EVENING. THE BEST 0-6KM SHEAR OF
GREATER THAN 35 KTS IS PROGGED OVER THE SOUTHEAST HALF OF THE
FORECAST AREA...OPPOSITE OF WHERE MOST OF THE CONVECTION WILL BE. ON
THE OTHER HAND...FREEZING LEVEL HEIGHTS ARE LOWER ON THE ORDER OF
10500 FT WHERE THE CONVECTION IS EXPECTED...THUS THERE COULD END UP
BEING MARGINALLY SEVERE HAIL. STORMS SHOULD GRADUALLY WEAKEN AS
INSTABILITY WANES LATE IN THE EVENING INTO THE OVERNIGHT HOURS. IT
SHOULD BE NOTED...IF FOR SOME REASON A STORM FIRES IN THE HIGHER
0-6KM SHEAR AREA THIS AFTERNOON...IT WOULD LIKELY BECOME
SUPERCELLULAR. AGAIN...THOUGH...THINK THIS IS A LOW PROBABILITY WITH
THAT AREA PERHAPS EVEN BEING CAPPED. SEE THE HYDROLOGY SECTION BELOW
FOR FLOODING CONCERNS.
CERTAINTLY THE ADDITIONAL RAIN FROM STORMS THIS AFTERNOON AND EARLY
EVENING WILL NOT HELP THE FLOODING MATTERS IN PORTIONS OF SOUTHEAST
MINNESOTA AND NORTHEAST IOWA. HAVE KEPT THE FLASH FLOOD WATCH GOING
TO 00Z THIS EVENING...WHICH WORKS OUT WELL IN TERMS OF TIME BECAUSE
THE CONVECTION SHOULD MOSTLY BE EAST OF THERE BY THE EXPIRATION.
SHOULD SEE QUITE A BIT OF SUN TODAY AND WITH 850MB TEMPS HOVERING IN
THAT 14-18C RANGE...TEMPERATURES SHOULD EASILY CLIMB INTO THE UPPER
70S TO MID 80S. ANOTHER MILD NIGHT LIKELY TONIGHT WITH PLENTY OF
CLOUDS AND DEWPOINTS REMAINING UP IN THE 50S TO LOW 60S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 341 AM CDT MON MAY 20 2013
TUESDAY THROUGH THURSDAY...
MAIN FOCUS HERE IS ON THE EVOLUTION OF THE UPPER LOW. 20.00Z
ECMWF/GFS/CANADIAN/NAM ARE ALL IN PRETTY GOOD AGREEMENT HOLDING THE
UPPER LOW NEARLY STATIONARY ON TUESDAY...THEN GRADUALLY SHIFTING
EASTWARD TUESDAY NIGHT AND WEDNESDAY BEFORE IT GETS MORE OF A KICK
EAST WEDNESDAY NIGHT. THE KICK EAST IS IN RESPONSE TO A POTENT
TROUGH DROPPING SOUTH THROUGH MUCH OF EASTERN CANADA.
FOR TUESDAY...MUCH OF THE FORECAST AREA WEST OF THE MISSISSIPPI
RIVER LOOKS TO BE DRY-SLOTTED...THUS HAVE LOWERED PRECIPITATION
CHANCES. TO THE EAST...THERE ARE INDICATIONS THAT SOME DIURNAL
CONVECTION COULD FORM ALONG A COLD FRONT MARCHING EAST. INSTABILITY
IS PRETTY MEAGER IN THIS CASE COMPARED TO WHAT WE HAVE BEEN DEALING
WITH...THUS ANY CONVECTION SHOULD NOT GO SEVERE. BETTER SHOT FOR
SEVERE WEATHER WILL BE WELL SOUTH AND EAST OF THE FORECAST AREA.
HIGHEST PRECIPITATION CHANCES OVERALL ARE EXPECTED NORTH OF HWY 29
IN A LOW TO MID LEVEL FRONTOGENESIS ZONE.
AS THE UPPER LOW BEGINS TO PUSH EAST TOWARDS THE FORECAST AREA
TUESDAY NIGHT AND WEDNESDAY...DPVA INCREASES WHILE SIMULTANEOUSLY
THE LOW TO MID LEVEL FRONTOGENESIS ZONE DROPS SOUTH. THEREFORE...
INCREASING PRECIPITATION CHANCES SEEM REASONABLE... ESPECIALLY ON
WEDNESDAY WHEN THE TWO FORCING MECHANISMS ARE JUXTAPOSTED.
ADDITIONALLY...THERE COULD BE SOME DIURNAL ENHANCEMENT ON WEDNESDAY
BEING CLOSE TO OR UNDER THE COLD CORE OF THE UPPER LOW.
MODELS APPEAR TO BE TRENDING FASTER IN KICKING OUT THE UPPER LOW FOR
WEDNESDAY NIGHT AND THURSDAY...ENOUGH SO THAT THURSDAY MAY NOW END
UP DRY. WEDNESDAY NIGHT STILL LOOKS FAVORABLE FOR PRECIPITATION...
ESPECIALLY EAST OF THE MISSISSIPPI RIVER WHICH IS IN THAT
AFOREMENTIONED JUXTAPOSITION OF FORCING MECHANISMS.
DEFINITELY A COOLING TREND WILL TAKE PLACE FOR TUESDAY THROUGH
THURSDAY WITH THAT UPPER LOW COMING IN...AND THEN COME THURSDAY A
NORTHERLY FLOW ADVECTING AIR FROM CANADIAN HIGH PRESSURE TRYING TO
BUILD SOUTH INTO THE UPPER GREAT LAKES. 850MB TEMPS FALL FROM 11-13C
AT 12Z TUE TO 4-6C BY 12Z THU. WENT WITH A BLEND OF GUIDANCE FOR
HIGHS AND LOWS FOR NOW GIVEN NO SIGNAL TO LEAN TOWARDS WARMER OR
COLDER SCENARIO GIVEN THE FORECAST PATTERN.
THURSDAY NIGHT INTO NEXT WEEKEND...
20.00Z ECMWF/GFS/CANADIAN AND GFS ENSEMBLES CONTINUE TO ADVERTISE A
BLOCKED UP UPPER LEVEL FLOW PATTERN ACROSS NORTH AMERICA DURING THE
EXTENDED PORTION OF THE FORECAST. THE FLOW FEATURES DEEP TROUGHING
ALONG THE WEST COAST...RIDGING FROM THE PLAINS INTO THE NORTHWEST
TERRITORIES...AND MEAN TROUGHING FROM EASTERN CANADA INTO THE
MID-ATLANTIC REGION. WHAT THIS PATTERN MEANS FOR THE FORECAST AREA
IS A BATTLE BETWEEN DRY...CANADIAN HIGH PRESSURE AND A MORE HUMID
AIRMASS ADVECTING NORTH OUT OF THE GULF OF MEXICO UNDER THE UPPER
RIDGE. IT APPEARS DRY CONDITIONS SHOULD PREVAIL FOR THURSDAY NIGHT
AND FRIDAY...RESULTING FROM SUBSIDENCE IN THE WAKE OF THE EARLY TO
MID WEEK UPPER LOW. FROM FRIDAY NIGHT AND BEYOND...HAVE FOLLOWED A
CONSENSUS APPROACH AND SPREAD PRECIPITATION CHANCES ACROSS THE
FORECAST AREA...HIGHEST WEST OF THE MISSISSIPPI RIVER. THESE CHANCES
ARE A RESULT OF SURGES OF WARM ADVECTION. THE PRECIPITATION COULD
BECOME ENHANCED TOO AT TIMES AS JET STREAKS PROPAGATE BETWEEN THE
EASTERN CANADA TROUGH AND PLAINS RIDGING.
SOMETHING TO WATCH DURING THE EXTENDED IS POTENTIAL FOR FROST...
ESPECIALLY IN CENTRAL WISCONSIN. THURSDAY NIGHT ACCORDING TO 20.00Z
MODELS WOULD BE THE HIGHEST CHANCE...THOUGH CONFIDENCE IS NOT HIGH
ENOUGH TO EITHER MENTION FROST IN THE FORECAST OR DROP LOWS BELOW
40. OTHERWISE...TEMPERATURES SHOULD STAY MOSTLY BELOW NORMAL BEING
UNDER THE INFLUENCE OF THE CANADIAN HIGH AND A NORTHEAST FLOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1235 PM CDT MON MAY 20 2013
AS UPPER LOW GETS CLOSER TO THE AREA...SOME STRATUS AND CUMULUS
FIELD WRAPING BACK INTO THE AREA FROM BRIEF CLEARING...BUT MOST
CEILINGS VFR. WATCHING FOR ADDITIONAL CONVECTION THIS AFTERNOON BUT
STORM OCCULUSION AND SLIGHTLY DRIER AIR IN THE FORM OF LOWER CAPE
VALUES MAY KEEP STORMS SLIGHTLY WEAKER THAN YESTERDAY...IN ADDITION
TO A BIT MORE SOUTH AND EAST. WILL KEEP STORMS IN A VICINITY MODE
UNTIL MORE DETAIL CAN BE WORKED IN BUT THREAT SHOULD END BY
OVERNIGHT HOURS AS ANY CAPE DIMINISHES.
GENERALLY A VFR CEILING EXPECTED AS UPPER LOW SPINS AROUND THE AREA
FOR ANOTHER DAY OR TWO BUT SOME MVFR TIME IS POSSIBLE WITH LOWER
STRATUS FIELDS OR ROUNDS OF SHOWERS.
&&
.HYDROLOGY...
ISSUED AT 1235 PM CDT MON MAY 20 2013
AS HEAVIEST RAIN FOCUS SHIFTS A BIT SOUTH AND EAST OF HARDEST HIT
AREAS...CONFIDENCE IN ADDITIONAL FLOODING PROBLEMS HAD DROPPED
ENOUGH TO CLEAR SOME OF THE WATCH. BUT REMAINING HIGH WATER AND
RISING RIVERS PROMPTED KEEPING REST OF COUNTIES GOING IN WATCH AT
LEAST INTO LATE AFTERNOON.
SEEMS LIKE BEST MOISTURE TRANSPORT IS FOCUSING ON AREAS OF EASTERN
IOWA INTO SOUTHERN WISCONSIN...WHICH CAN HANDLE A BIT MORE RAIN. NO
CURRENT PLANS TO EXPAND ANY WATCHES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...FLASH FLOOD WATCH THROUGH THIS EVENING FOR MNZ086-087-094-095.
IA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR IAZ008.
&&
$$
SHORT TERM...AJ
LONG TERM....AJ
AVIATION.....SHEA
HYDROLOGY....AJ