Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/12/13
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
428 PM PDT SUN AUG 11 2013
.DISCUSSION...AS OF 1:36 PM PDT SUNDAY...AN UPPER TROUGH OFF THE
CA COASTLINE CONTINUED TO DOMINATE THE WEATHER PATTERN...WITH
MODERATE ONSHORE FLOW AND ABUNDANT STRATUS OFFSHORE. IN FACT...THE
ONSHORE GRADIENT ACTUALLY STRENGTHENED THIS AFTERNOON COMPARED TO
YESTERDAY AFTERNOON...RESULTING IN COOLER TEMPERATURES ALONG THE
COAST. AT THE SAME TIME...A VERY SUBTLE WARMING TREND OCCURRED
INLAND...WITH TEMPERATURES RANGING FROM THE 70S TO MID 80S
INLAND. THESE TEMPERATURES ARE STILL ABOUT 5 TO 10 DEGREES BELOW
NORMAL FOR THE MIDDLE OF AUGUST.
ANOTHER TYPICAL EVENING IS IN STORE FOR THE REGION...AS THE MARINE
LAYER REMAINS AROUND 1500 FEET...WITH PATCHY COASTAL DRIZZLE
POSSIBLE AGAIN LATE TONIGHT/EARLY MONDAY MORNING. BOTH THE NAM AND
HRRR INDICATE ISOLATED AREAS OF 0.01" TO 0.02" UP AND DOWN THE
COASTLINE. THE NAM AND HRRR CONTINUE TO VERIFY WELL WITH REGARDS
TO DRIZZLE...SO IT WAS ADDED TO THE ENTIRE COASTLINE.
A WARMING TREND WILL CONTINUE MONDAY INTO THE MIDDLE OF NEXT WEEK
AS AN UPPER LEVEL RIDGE SETS UP OVER THE FOUR CORNERS REGION WITH
HIGH PRESSURE NUDGING WEST INTO CA. 850 MB TEMPERATURES ARE
FORECAST TO RISE FROM THE 17 DEGREES C RANGE MONDAY AFTERNOON...TO
BETWEEN 21 AND 23 DEGREES C BY WEDNESDAY AFTERNOON. THIS WILL
RESULT IN DAYTIME HIGH TEMPERATURES CLIMBING INTO THE 80S TO MID
90S INLAND...NEAR NORMAL FOR THE MIDDLE OF AUGUST. TEMPERATURES
ALONG THE COAST WILL REMAIN MILD...AS COASTAL LOW CLOUDS WILL BE
PRESENT EACH NIGHT INTO THE MORNING HOURS...WITH TEMPERATURES
MAINLY IN THE 60S.
BY THURSDAY...A SIGNIFICANT UPPER LEVEL LOW WILL MOVE EAST TOWARD
THE PAC NW COASTLINE...WITH AN UPPER TROUGH DIGGING SOUTH AND
IMPACTING THE CA COAST. THIS WILL RESULT IN A DEEPENING MARINE
LAYER...STRONGER ONSHORE FLOW...AND A COOLING TREND INTO AT LEAST
FRIDAY.
OTHERWISE...NO MAJOR CHANGES TO THE FORECAST...WITH A PERSISTENT
DRY WEATHER PATTERN AND SUBTLE VARIATIONS WITH REGARDS TO THE
MARINE LAYER AND TEMPERATURE FORECAST.
&&
.AVIATION...AS OF 4:30 PM PDT SUNDAY...UPPER LEVEL TROUGH OFF THE
COAST HAS KEPT STRATUS ALONG THE COAST ALL DAY. THERE IS MORE OF
A NORTHWEST FLOW TODAY AS OPPOSED TO A MORE WESTERLY FLOW
YESTERDAY. AS A RESULT CIGS SHOULD GET INTO SFO SLIGHTLY LATER
THAN YESTERDAY BUT WILL STILL COME IN EARLY TENOUGH TO IMPACT THE
AIRPORT EVENING RUSH.
VICINITY OF KSFO...MVFR BY 03Z BECOMING IFR BY 12Z WITH BASES
NEAR 800 FEET. WEST WINDS GUSTING TO 20-22 KNOTS THROUGH 04Z.
KSFO BRIDGE APPROACH...SAME AS KSFO.
MONTEREY BAY AREA TERMINALS...IFR CIGS.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...NONE.
$$
PUBLIC FORECAST: RILEY
AVIATION/MARINE: W PI
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AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
207 PM PDT SAT AUG 10 2013
.DISCUSSION...AS OF 2:06 PM PDT SATURDAY...AN UPPER LOW OFF THE
NORTHERN CA COASTLINE CONTINUES TO DOMINATE THE WEATHER
PATTERN...WITH MODERATE ONSHORE FLOW AND BELOW SEASONABLE NORMAL
TEMPERATURES. THIS AFTERNOON...TEMPERATURES ROSE INTO THE 60S
ALONG THE COAST...TO THE 70S INLAND. ONE OF THE WARMEST SPOTS OF
THE DAY WAS PINNACLES NATIONAL PARK...AT 87 DEGREES. TEMPERATURES
ARE FORECAST TO RISE ANOTHER FEW DEGREES BEFORE SUNSET. THESE
TEMPERATURES ARE BETWEEN 5 AND 10 DEGREES BELOW NORMAL FOR THE
MIDDLE OF AUGUST.
THE MARINE LAYER...CURRENTLY AROUND 1500 FEET...IS FORECAST TO
DEEPEN TO AROUND 2000 FEET AGAIN OVERNIGHT...WITH ABUNDANT STRATUS
INLAND. PATCHY COASTAL DRIZZLE IS ALSO POSSIBLE AGAIN
OVERNIGHT...AS BOTH THE NAM AND HRRR INDICATE MANY AREAS OF 0.01"
OF ACCUMULATION LATE TONIGHT/EARLY SUNDAY MORNING. TEMPERATURES
ARE FORECAST TO FALL INTO THE 50S OVERNIGHT...SIMILAR TO THOSE
OBSERVED LAST NIGHT.
A SUBTLE WARMING TREND IS FORECAST TO TAKE PLACE TOMORROW THROUGH
AT LEAST THE MIDDLE OF NEXT WEEK...AS THE UPPER LOW SHIFTS SLOWLY
NORTH WITH UPPER LEVEL HIGH PRESSURE OVER THE SOUTHWEST US NUDGING
NORTHWEST INTO THE AREA. 850 MB TEMPERATURES ARE FORECAST TO RISE
BETWEEN 1 AND 2 DEGREES C BETWEEN THIS AFTERNOON AND SUNDAY
AFTERNOON...RESULTING IN INLAND TEMPERATURES WARMING INTO THE MID
70S TO MID 80S. IN FACT...SOUTHERN MONTEREY AND SAN BENITO
COUNTIES ARE FORECAST TO REACH THE MID 90S.
THE MARINE LAYER WILL ALSO COMPRESS BEGINNING SUNDAY NIGHT AND
CONTINUING OVER THE NEXT FEW DAYS...AIDING IN THE WARMING TREND.
BY WEDNESDAY...TEMPERATURES INLAND WILL RISE INTO THE UPPER 70S TO
UPPER 80S...NEAR NORMAL FOR THE MIDDLE OF AUGUST.
ON A SIDE NOTE...THE CLIMATE PREDICTION CENTER 8 TO 14 DAY OUTLOOK
(VALID FROM AUGUST 18TH THROUGH AUGUST 24TH) CALL FOR SLIGHTLY
ABOVE NORMAL TEMPERATURES...MAINLY FOR THE INLAND LOCATIONS.
&&
.AVIATION...AS OF 11:21 AM PDT SATURDAY...AN UPPER LEVEL LOW
PRESSURE SYSTEM THAT HAS AFFECTED OUR REGION OVER THE LAST FEW
DAYS HAS SHIFTED TO OUR NORTH AS A RIDGE OF HIGH PRESSURE
ORIGINATED IN THE DESERT SOUTHWEST BEGINS TO BUILD INTO
CALIFORNIA. STRATUS IS EXPECTED TO CLEAR BY EARLY THIS AFTERNOON
FOR ALL TERMINALS. GENERALLY LIGHT WINDS ARE EXPECTED FOR THE
MAJORITY OF THE FORECAST REGION THROUGHOUT THE DAY. STRATUS IS
EXPECTED TO RETURN BY THIS EVENING. ALL TERMINALS ARE EXPECTED TO
HAVE LOW CEILINGS BY LATE THIS EVENING AND INTO THE MORNING HOURS.
PATCHY DRIZZLE IS LIKELY. CLEARING TIMES TOMORROW WILL BE SIMILAR
TO TODAY.
VICINITY OF KSFO...MVFR CONDITIONS ARE EXPECTED TO IMPROVE TO VFR
CONDITIONS BY MID-DAY. WIND SPEEDS WILL INCREASE TO 15KT
AND GUSTS TO 20KT BY THIS AFTERNOON. CONDITIONS ARE FORECAST TO
DIMINISH TO MVFR BY LATE THIS EVENING AS THE STRATUS RETURNS.
CONDITIONS ARE EXPECTED TO IMPROVE TO VFR TOMORROW AT AROUND THE
SAME TIME AS TODAY...IF NOT SLIGHTLY EARLIER.
KSFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY AREA TERMINALS...MVFR CONDITIONS AT THE MONTEREY
TERMINAL ARE EXPECTED TO IMPROVE TO VFR BY MID-DAY. BOTH
TERMINALS ARE FORECAST TO HAVE LIGHT WINDS AND VFR CONDITIONS THROUGH
THE DAY THAT WILL LAST INTO THE EARLY EVENING WHEN CONDITIONS ARE
EXPECTED TO DIMINISH TO MVFR. CONDITIONS WILL FURTHER DEGRADE TO
VFR OVERNIGHT IN THE EARLY MORNING HOURS WITH DRIZZLE LIKELY NEAR
THE COAST.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...NONE.
$$
PUBLIC FORECAST: RILEY
AVIATION/MARINE: SIERRA/SIMS
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AREA FORECAST DISCUSSION
NWS PUEBLO CO
1126 AM MDT SAT AUG 10 2013
.UPDATE...
ISSUED AT 1052 AM MDT SAT AUG 10 2013
STILL A THREAT FOR SOME LOCALLY HEAVY RAIN THIS AFTERNOON AND
EVENING. LOW CLOUDS ALONG PORTIONS OF THE INTERSTATE 25 CORRIDOR
HAVE DELAYED SURFACE HEATING. MESONET OBSERVATIONS SUGGEST SOME
DRIER MID LEVEL AIR IS OVER THE EASTERN MOUNTAINS OF
COLORADO...BUT BELIEVE SOME MOISTURE MAY ADVECT INTO THE REGION
FROM THE SOUTH THIS AFTERNOON. SHORTWAVE APPEARS TO BE MOVING INTO
SOUTHWEST COLORADO AND IS CONTINUING TO MOVE NORTHEAST. WITH THE
LESS HEATING AND SHORTWAVE OVER EXTREME SOUTHWEST
COLORADO...BELIEVE CONVECTION OVER EASTERN MOUNTAINS WILL BE
DELAYED. HRRR AND LOCAL WRF SUGGEST CONVECTION WILL DEVELOP OVER
THE EASTERN MOUNTAINS...INCLUDING WALDO CANYON REGION...AROUND 3
TO 4 PM TODAY. GIVEN VERY MOIST SOIL CONDITIONS AND POTENTIAL FOR
LOCALLY HEAVY DOWNPOURS...WILL CONTINUE FLASH FLOOD WATCH. WATCH
MAY START TOO EARLY...BUT WILL LEAVE IT ALONE TO AVOID ANY
CONFUSION. SHORTWAVE MOVING INTO WESTERN COLORADO WILL DEVELOP
CONVECTION AROUND WEST FORK COMPLEX AROUND 2 PM.
.UPDATE ISSUED AT 737 AM MDT SAT AUG 10 2013
UPDATED SHORT TERM FORECASTS TO REFLECT CURRENT CONDITIONS. LW
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 555 AM MDT SAT AUG 10 2013
...ANOTHER ROUND OF STORMS TODAY WITH HEAVY RAIN POTENTIAL...
PATTERN TODAY SHAPING UP VERY SIMILAR TO YESTERDAY. AN ACTIVE
DISTURBANCE VISIBLE IN SATELLITE PICTURES OVER NEW MEXICO THIS
MORNING IS POISED TO WORK ITS WAY NORTHWARD INTO WESTERN COLORADO
LATER THIS MORNING...AND THEN EASTWARD ACROSS THE PIKES PEAK REGION
IN THE AFTERNOON. HI RES MODELS SHOW ANOTHER ROUND OF CONVECTION
DEVELOPING OVER TELLER AND EL PASO COUNTIES BETWEEN APPROXIMATELY 3
AND 6 PM. GIVEN THIS INFORMATION...AND THE FACT THAT THE SOILS ON
THE WALDO ARE CURRENTLY SATURATED AND UNSTABLE FROM THE HEAVY RAIN
THAT FELL YESTERDAY...WE WILL POST A FLASH FLOOD WATCH FOR THE WALDO
CANYON BURN SCAR AREA FROM NOON UNTIL 9 PM MDT TODAY.
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER MOST OF THE
AREA AGAIN THIS AFTERNOON AND EVENING. AGAIN...THE MONSOON REMAINS
ACTIVE WITH THE PLUME SENDING DISTURBANCES OUR WAY. IN ADDITION...
THE LOWER LEVELS OF THE ATMOSPHERE CONTAIN PLENTY OF MOISTURE TO
WORK WITH...WITH SURFACE DEWPOINTS AROUND THE AREA WIDESPREAD IN THE
50S ACROSS THE PLAINS...AND MOSTLY IN THE 40S IN THE HIGH COUNTRY.
SO...ONCE AGAIN TODAY...THE PRIMARY WEATHER CONCERN WILL BE LOCALLY
HEAVY RAIN...WITH THE POTENTIAL FOR FLASH FLOODING...ESPECIALLY IN
AND NEAR AREA BURN SCARS...MOST NOTABLY INCLUDING THE WALDO CANYON
BURN SCAR WHERE IT RAINED SO HARD YESTERDAY AND THE SOILS ARE
ALREADY SATURATED AND UNSTABLE.
HIGH WATER LEVELS ARE OCCURRING IN MANY PARTS OF SOUTHERN COLORADO
AT THIS TIME. MANY EPHEMERAL STREAMS...OR STREAMS THAT TYPICALLY
ONLY FLOW BRIEFLY DURING AND FOLLOWING A PERIOD OF RAINFALL...ARE
CURRENTLY RUNNING FULL. MANY SMALL STREAMS AND ARROYOS HAVE SEEN
HIGH WATER OR FLOODING IN RECENT DAYS. A NUMBER OF SMALLER EARTHEN
DAMS AND AGRICULTURAL DIVERSIONS ARE SEEING STRESS THAT THEY HAVEN`T
SEEN FOR A WHILE. THE PAST SEVERAL DAYS OF THE MONSOON HAVE BEEN
RATHER EXCEPTIONAL BY SOUTHERN COLORADO STANDARDS...WITH NUMEROUS
REPORTS OF FLOODING COMING IN FROM ALL AREAS...BOTH URBAN AND RURAL.
ADDITIONAL RAINS COMING IN THE DAYS AHEAD WILL ONLY EXACERBATE THE
SITUATION. IF YOU HAVEN`T ALREADY DONE SO...NOW IS A GOOD TIME TO
MAKE PREPARATIONS FOR HIGH WATER AND FLOODING. WHAT WOULD YOU DO
IF WATER WAS SUDDENLY SURROUNDING YOUR HOUSE OR VEHICLE? THINK
ABOUT IT NOW...SO YOU KNOW WHAT TO DO THEN.
OTHER POTENTIAL WEATHER HAZARDS WITH STORMS TODAY WILL INCLUDE
LIGHTNING...STRONG GUSTY WINDS TO AROUND 50 MPH...AND SMALL
HAIL. LW
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 555 AM MDT SAT AUG 10 2013
LONGER TERM METEOROLOGICAL CONDITIONS CONTINUE TO BE IMPACT
ADDITIONAL PRECIPITATION WILL HAVE ON AREA BURN SCARS(ESPECIALLY
THE WALDO CANYON BURN AND BLACK FOREST BURN SCARS)...TEMPERATURES
AND POPS.
WARMER AND SOMEWHAT DRIER CONDITIONS ARE STILL EXPECTED TO
DEVELOP OVER THE FORECAST DISTRICT FROM SUNDAY INTO EARLY MONDAY
WITH MODEL SOUNDING PRECIPITABLE WATER VALUES EXPECTED TO REMAIN
UNDER ONE INCH OVER AREAS SUCH AS THE I-25 CORRIDOR DURING THIS
TIME-FRAME.
AS MENTIONED IN PREVIOUS DISCUSSIONS...ALTHOUGH A SOMEWHAT DRIER
AIRMASS WILL BE LOCATED OVER SOUTHERN COLORADO...STILL ANTICIPATE
THAT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS IN
COMBINATION WITH WARMER TEMPERATURES WILL BE NOTED OVER THE CWFA
FROM THIS WEEKEND INTO EARLY MONDAY AFTERNOON. PLEASE REMEMBER
THAT SOME OF THE STRONGER THUNDERSTORMS WILL BE CAPABLE OF
PRODUCING LOCALIZED HEAVY RAINFALL AS WELL AS POTENTIAL BURN SCAR
FLOODING ISSUES DURING THE PERIOD.
RECENT FORECAST MODEL SOUNDINGS AND COMPUTER SIMULATIONS CONTINUE
TO INDICATE THAT INCREASINGLY MOIST EASTERLY FLOW WILL ALLOW
PRECIPITABLE WATER VALUES TO EXCEED ONE INCH AT TIMES AGAIN OVER
PORTIONS OF THE EASTERN MOUNTAINS AND THE I-25 CORRIDOR(INCLUDING
THE WALDO CANYON AND NEARBY BURN SCARS)...ESPECIALLY DURING THE
AFTERNOON AND EVENING HOURS.
THIS WILL ALLOW FOR INCREASED POPS IN COMBINATION WITH NEAR
SEASONAL MID-AUGUST TEMPERATURES FROM LATER MONDAY INTO AT LEAST
WEDNESDAY. LOCALLY HEAVY RAINFALL WILL AGAIN BE POSSIBLE DURING
THIS TIME-FRAME AND ANOTHER ROUND OF BURN SCAR FLOODING ISSUES
WILL BE POSSIBLE DURING THIS PERIOD. WFO PUEBLO WILL CONTINUE TO
MONITOR CLOSELY.
LATEST LONGER TERM DATA STILL SUGGESTS THAT THE HIGHEST POTENTIAL
FOR LOCALIZED HEAVY RAIN NEXT WEEK SHOULD BE NOTED FROM LATER
MONDAY INTO WEDNESDAY BEFORE SOMEWHAT DRIER AND WARMER CONDITIONS
ATTEMPT TO DEVELOP OVER THE MAJORITY OF THE FORECAST DISTRICT FROM
THURSDAY INTO EARLY FRIDAY AFTERNOON IN ADVANCE OF NEXT RELATIVELY
MOIST NORTH-NORTHEASTERLY SURGE BY LATER FRIDAY/FRIDAY NIGHT.
FINALLY...LOW-GRADE GRADIENT WINDS ARE ANTICIPATED OVER THE
MAJORITY OF THE FORECAST DISTRICT FROM SUNDAY INTO NEXT FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1052 AM MDT SAT AUG 10 2013
ANOTHER DAY WITH THE MONSOON PLUME OVER THE REGION AND SOME LOW
LEVEL MOISTURE ON THE PLAINS. THUNDERSTORMS WILL DEVELOP OVER THE
MOUNTAINS AND HIGH VALLEYS AROUND 19Z TO 20Z. CONVECTION IS
EXPECTED TO DEVELOP OVER PORTIONS OF THE EASTERN MOUNTAINS AROUND
21Z AND MOVE TO THE EAST. CONVECTION SHOULD END BY MID EVENING AS
A SHORTWAVE PASSES THROUGH THE REGION. LOWER LEVELS SHOULD BE DRIER
TONIGHT ON THE PLAINS AND DO NOT ANTICIPATE ANY LOW CLOUDS OR FOG
AT KCOS AND KPUB.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
FLASH FLOOD WATCH UNTIL 9 PM MDT THIS EVENING FOR COZ081-084-085.
&&
$$
UPDATE...PGW
AVIATION...PGW
AREA FORECAST DISCUSSION
NWS TAUNTON MA
721 PM EDT SUN AUG 11 2013
.SYNOPSIS...
MOISTURE BEGINS TO BUILD BACK INTO THE REGION LATE THIS EVENING
WITH ACCOMPANYING LIGHT SHOWERY WEATHER AS HIGH PRESSURE EXITS
EAST AND OFFSHORE. MUGGY CONDITIONS INCREASE MONDAY NIGHT AND INTO
TUESDAY AHEAD OF AN APPROACHING COLD FRONT WHICH WILL BRING
SCATTERED SHOWERS AND THUNDERSTORMS INTO TUESDAY NIGHT. DRY AND
SEASONABLE WEATHER RETURNS FOR THE REST OF THE WEEK AND INTO NEXT
WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
715 PM UPDATE...
NO REAL CHANGES TO FORECAST WHICH IS ON TRACK. NOTING INCREASE IN
CLOUD COVER IN NORTHERN PA. RAP MODEL INDICATES HIGHER 925 MB RH
OVERSPREADING CT AND RI LATE TONIGHT THEN EXITING SE MA IN THE
MORNING. SOME SHOWERS IN SOUTHERN PA. WILL KEEP OUR EYES ON THESE
TO SEE IF THERE IS ANY NORTHWARD PROGRESSION OVERNIGHT.
PREVIOUS DISCUSSION...
REMAINING DRY AND SEASONABLE INTO THE EVENING HOURS. WILL SEE THE
INCREASE OF CLOUDS OUT OF THE SOUTH AND WEST AS FORECAST GUIDANCE
INDICATES A CONTINUED SIGNAL OF RAIN CHANCES ALONG THE SOUTH COAST
OVERNIGHT... A CONSEQUENCE OF THE SURFACE FRONTAL BOUNDARY OVER
THE OHIO RIVER VALLEY AND MID- ATLANTIC LIFTING NORTH AS A WARM
FRONT. THE RETURN SOUTHERLY FLOW AND RETURN OF MORE TROPICAL AIR
IS COLLOCATED ALONG THE H85 THERMAL GRADIENT AND A WEAK AREA OF
LOW PRESSURE SLIDING ALONG THE LIFTING WARM FRONT. THIS PROMOTES
THE OPPORTUNITY FOR LOW- LEVEL LOCALIZED CONVERGENCE AND RAIN
CHANCES.
WITH LITTLE IN THE WAY OF STRONG DYNAMICS AND UPPER-LEVEL SUPPORT...
FEEL VERY LIGHT SHOWERS WILL BE THE OUTCOME...THE NORTHERN EXTENT OF
WHICH /ALONG THE MASSACHUSETTS TURNPIKE/ WILL BE SUPPRESSED BY LOW-
LEVEL DRY AIR AND DEPARTING HIGH PRESSURE. WITH THE RETURN OF HIGHER
DEWPOINTS...LOWS WILL BE RESTRICTED TO AROUND THE MID- TO UPPER-
50S.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
MONDAY...
WARM FRONT CONTINUES TO SLOWLY LIFT NORTHWARD AGAINST DRIER AIR AND
HIGH PRESSURE. IT REMAINS DIFFICULT TO PINPOINT EXACTLY WHERE AND
WHEN SHOWER ACTIVITY...IF ANY...WILL EVOLVE. MAIN FOCUS WILL BE UPON
LOCALIZED CONVERGENCE AHEAD OF THE NOSE OF TROPICAL AIR FROM THE
SOUTH COLLOCATED WITH THE BEST THERMAL AXIS. SOME HINT OF SUPPORT
ALOFT AS INITIAL MID-LEVEL ENERGY FLOWS THROUGH THE LONGWAVE FLOW IN
A REGION OF INCREASING DIFFLUENCE AHEAD OF AN APPROACHING TROUGH
AXIS FOR MONDAY NIGHT INTO TUESDAY.
WILL GO WITH CHANCE POPS WITH THE EXPECTATION OF LIGHT SPOTTY
ACTIVITY...POTENTIALLY INVIGORATED BY BOUNDARY LAYER DESTABILIZATION
AS SUNSHINE BETWEEN THE SCATTERED TO BROKEN CLOUD DECK IS EXPECTED.
INSTABILITY IS MEAGER ADMIST MODEST SHEAR...SO WILL MENTION ISOLATED
THUNDER. HIGHS AROUND THE UPPER 70S TO LOW 80S WITH DOMINANT
SOUTHERLY FLOW.
MONDAY NIGHT...
SURFACE WARM FRONT MOVES QUICKLY NORTH WITH AMPLIFICATION OF
SOUTHERLY FLOW AT THE SURFACE IN RESPONSE TO THE APPROACHING MID-
LEVEL TROUGH AXIS AND ACCOMPANYING SURFACE COLD FRONT INTO THE
EASTERN GREAT LAKES.
SHOULD SEE CONTINUED SHOWERY WEATHER AS THE BETTER DYNAMICS CONTINUE
TO LAG WEST. CHANCE POPS ACCORDINGLY WITH LIKELY POPS FOR THE
WESTERN ZONES AS BETTER DYNAMICS AND DEEP-LAYER LIFT APPROACH.
CONTINUED MENTION OF ISOLATED THUNDER. SUSTAINED SURFACE DEWPOINTS
AROUND THE MID TO UPPER 60S WILL MAKE FOR A MILD EVENING WITH LOWS
OF SIMILAR RANGE.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
BIG PICTURE/PREFERENCES...
MAIN WEATHER FEATURE FOR THE WEEK IS A SHORTWAVE TROUGH MOVING
THROUGH NEW ENGLAND ON TUE NIGHT AND ITS ASSOCIATED SURFACE COLD
FRONT SWINGING THROUGH THE REGION. A DEEPER TROUGH IS FORECAST TO
DEVELOP OVER THE MIDWEST/OHIO VALLEY BY THE END OF THE WEEK WHICH
LEADS TO SURFACE LOW PRESSURE DEVELOPMENT OVER THE SOUTHEAST
STATES. HOWEVER...CONFLUENT UPPER FLOW OVER NORTHERN NEW ENGLAND
IS ASSOCIATED WITH A STRONG SURFACE HIGH PRESSURE RIDGE WHICH
WILL PROTECT OUR REGION FROM PRECIPITATION THAT ADVANCES FROM THE
SOUTH...AT LEAST THROUGH THE FIRST HALF OF NEXT WEEKEND.
THE GFS MODEL GENERATES A TROPICAL TYPE OF SYSTEM OVER THE GULF
COAST AND ITS MOISTURE ADVANCES UP THE APPALACHIANS NEXT WEEKEND.
THE ECMWF ALSO HAS MOIST LOW PRESSURE ALONG THE GULF COAST BUT IT
IS NOT CLEAR IF IT HAD TROPICAL ORIGINS. IN ANY CASE...IT LOOKS
LIKE OUR NEXT CHANCE OF SHOWERS...AFTER TUESDAY NIGHT...WILL HOLD
OFF UNTIL NEXT SUNDAY.
GFS AND ECMWF ARE SIMILAR UNTIL LATE IN THE WEEK REGARDING
TEMPERATURES. BUT THEN THE ECMWF IS MORE MOIST WHICH HOLDS MAX
TEMPS TO 70S. GFS HAS PROTECTIVE SURFACE RIDGE AND MORE SUNSHINE
WHICH ALLOWS FOR MAXES IN THE LOWER 80S. PREFERRED THIS SOLUTION
BASED ON STRENGTH OF UPPER CONFLUENCE.
THE DAILIES...
TUESDAY AND TUESDAY NIGHT...
SHOWERS AND THUNDERSTORMS ARE LIKELY AS A COLD FRONT MOVES THROUGH
THE REGION...ACCOMPANIED BY THE PASSAGE OF AN UPPER LEVEL
SHORTWAVE TROUGH. PRECIPITABLE WATER VALUES INCREASE TO 1.5 INCHES
IN THE SOUTHEASTERN HALF OF THE REGION AND SURFACE DEWPOINTS REACH
65 TO 70...SO LOCALLY HEAVY RAIN IS A POSSIBILITY. THE NAM SHOWS A
SURFACE LOW SPINNING UP ALONG THE FRONT IN CENTRAL MA WHICH
ENHANCES THE RAINFALL POTENTIAL AND ALSO INCREASES HELICITY
VALUES. THE GFS AND ECMWF DO NOT HAVE THIS FEATURE. NEVERTHELESS
WILL NEED TO WATCH FOR THE POTENTIAL FOR WIND GUSTS APPROACHING
SEVERE THRESHOLDS. 850 MB WINDS REACH 20-25 KT IN THE LATE
AFTERNOON WITH 700 MB WINDS NEAR 30 KT...GUSTY BUT PROBABLY BELOW
SEVERE LIMITS. WHILE THE UPPER LEVEL 300 MB JET WILL BE
STRENGTHENING TO 105 KT TOWARD EVENING...SOUTHERN NEW ENGLAND
WILL BE IN THE CONVECTIVELY UNFAVORABLE RIGHT FRONT QUADRANT OF
THE JET.
MODELS ARE IN GOOD AGREEMENT ON THE TIMING OF THE ENDING OF THE
PRECIPITATION...BY MIDNIGHT TOWARD THE COAST AS THE FRONT MOVES
OFFSHORE. A SHOT OF COLD ADVECTION ON GUSTY NW WINDS WILL TAKE
PLACE LATE TUE NIGHT.
WEDNESDAY...
DRY AND COOLER WEATHER WITH HIGHS IN THE 70S TO NEAR 80 ON THE
SOUTH COAST. NW WINDS COULD GUST TO 20 MPH ESPECIALLY IN THE
MORNING NEAR THE COAST AS THE COLD AIR ADVECTION CONTINUES. WINDS
WILL DIMINISH IN THE AFTERNOON AS THE GRADIENT RELAXES AND HIGH
PRESSURE BEGINS TO SETTLE OVER THE AREA.
WEDNESDAY NIGHT THROUGH SATURDAY...
SURFACE HIGH PRESSURE IS PARKED OVER THE REGION PROVIDING MOSTLY
SUNNY DAYS AND MOSTLY CLEAR NIGHT. IT WILL BE ON THE CHILLY SIDE
LATE WED AND THU NIGHTS WITH LOWS IN THE MID AND UPPER 40S IN
OUTLYING AREAS OF NW MA AND SW NH. THERE WILL BE A WARMING TREND
LATER IN THE WEEK WITH HIGHS REACHING THE LOWER 80S BOTH THU AND
FRI...AND 80 TO 85 ON SAT. CLOUDINESS WILL BE TRYING TO ADVANCE
FROM THE SOUTH. WILL NEED TO KEEP AN EYE ON THIS BUT THINK IT WILL
STAY FAR ENOUGH SOUTH FOR SAT.
SUNDAY...CLOUDS SHOULD INCREASE FROM SOUTH TO NORTH BUT THINK IT
WILL REMAIN DRY. AM FORECASTING HIGHS IN THE UPPER 70S TO LOWER
80S.
&&
.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW THROUGH MONDAY NIGHT...HIGH CONFIDENCE.
VFR. WILL SEE WESTERLY FLOW VEER MORE SOUTHERLY GRADUALLY WITH
TIME ALONG WITH INCREASING -RA CHANCES /VERY ISOLATED TSRA MAINLY
LATE IN THE PERIOD/ AND LOWERING CIGS DOWN TO LOW-END VFR. THERE
IS ALSO SOME CONCERN OF PATCHY DENSE FOG TO WHICH CONFIDENCE IS
WAIVERING. AS FOR IFR-MVFR WITH FOG...BEST CHANCES APPEAR FOR
MON NIGHT INTO TUE MORNING ALONG THE SOUTH COAST.
KBOS TERMINAL...HIGH CONFIDENCE IN TAF. WILL BE ON THE NORTHERN EDGE
OF SOME BKN050 CLOUDINESS TOWARD DAYBREAK AND DURING THE MORNING
MON.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF. SHOULD SEE INCREASE IN
BKN050 CLOUD COVER LATE TONIGHT INTO MON.
OUTLOOK...TUESDAY THROUGH FRIDAY...
TUESDAY/TUESDAY NIGHT...MODERATE CONFIDENCE. MVFR CIGS WITH LOCAL
IFR VSBYS IN SHOWERS/LOCALLY HEAVY THUNDERSTORMS. SW WINDS MAY
GUST TO 30 KT IN STORMS. WINDS SHIFTING TO THE NW BEHIND THE COLD
FRONT TUE NIGHT AND MAY GUST TO 20-25 KT TOWARD DAYBREAK.
WEDNESDAY THROUGH FRI...HIGH CONFIDENCE VFR WITH LIGHT WINDS.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW THROUGH MONDAY NIGHT...HIGH CONFIDENCE.
WINDS GRADUALLY BACKING TOWARD THE SOUTH-SOUTHEAST THIS EVENING
INTO MONDAY. WILL SEE ENHANCEMENT INTO MONDAY NIGHT WITH WINDS
TURNING OUT OF THE SOUTHWEST WITH GUSTS UP TO 20 KTS POSSIBLE.
WILL SEE AN INCREASE IN RAIN CHANCES WITH ISOLATED THUNDERSTORMS
THROUGH THE PERIOD...WITH THE LOW POTENTIAL PRESENTLY OF
VISIBILITY RESTRICTIONS WITH ANY WET WEATHER. OVERALL
THEME...WINDS AND SEAS TO REMAIN BELOW SMALL CRAFT CRITERIA.
OUTLOOK...TUESDAY THROUGH FRIDAY...
HIGH CONFIDENCE. WINDS AND SEAS EXPECTED TO REMAIN BELOW SCA
THROUGH PERIOD.
TUESDAY...A COLD FRONT APPROACHES THE WATERS DURING THE DAY AND
MOVES ACROSS THE WATERS TUE NIGHT. SHOWERS AND TSTMS ARE LIKELY.
SEAS MAY BUILD TO 4 FT...BUT LOCALLY HIGHER IN TSTMS. A PERIOD OF
GUSTY NW WINDS...TO 20 TO 25 KT IS POSSIBLE BEHIND THE FRONT
TOWARD DAYBREAK WED.
WEDNESDAY...NORTHWEST TO NORTHEAST WINDS BEHIND THE FRONT COULD
REACH 20 TO 25 KT...AND SEAS ON THE OUTER WATERS COULD BRIEFLY
REACH 5 FT MAINLY IN THE MORNING. WINDS WILL DIMINISH AS HIGH
PRESSURE BUILDS IN LATER IN THE DAY.
THURSDAY AND FRIDAY...QUIET WEATHER WITH AFTERNOON SEA BREEZES.
LIGHT WINDS AND SEAS GENERALLY 2 FT OR LESS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SIPPRELL/FIELD
NEAR TERM...SIPPRELL/FIELD
SHORT TERM...SIPPRELL
LONG TERM...FIELD
AVIATION...SIPPRELL/FIELD
MARINE...SIPPRELL/FIELD
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
936 AM EDT SAT AUG 10 2013
.SYNOPSIS...
A FRONT JUST SOUTH OF THE REGION THIS MORNING WILL MOVE LITTLE OVER
THE NEXT FEW DAYS. A FEW WEAK AREAS OF LOW PRESSURE WILL RIDE ALONG
THE FRONT SUNDAY THROUGH TUESDAY. A COLD FRONT WILL CROSS THE AREA
LATER TUESDAY. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT AND
REMAIN INTO LATE NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH THIS ESTF UPDATE, WE ARE GOING TO ADD A CHANCE OF SPRINKLES
SOUTH IN LINE CLOSEST WITH LATEST HRRR AND COSPA AS THEY ARE
FOLLOWING THE RADAR REFLECTIVITIES WELL. AS TO WHERE PCPN IS
REACHING THE GROUND, AOO FIRST NORTH OF MASON DIXON STATION TO
OBSERVE IT. MEASURABLE RAIN IS AS FAR EAST AS EASTERN WEST
VIRGINIA. THIS IS FARTHER EAST THAN THE LATEST RAP. THE IAD
SOUNDING IS DRY BLO 600MB AND WAL IS MOISTER BUT THAT AIR MASS IS
HEADING OUT TO SEA. IAD IN PARTICULAR CORROBORATES THE 06Z GFS
IDEA THAT OUR CWA WILL NOT BEING CONVECTIVELY ABLE TODAY. SO THE
QUESTION THEN BECOMES HOW MUCH OF THIS PCPN REACHES THE GROUND
FROM THE MID LEVEL CLOUD DECK. WE WILL FOLLOW IT THE REST OF THIS
MORNING, BUT FOR NOW FIGURE THERE WILL BE SOME "DROPS ON THE
WINDSHIELD SOUTH" AND NOT EXPECTING MORE THAN THAT. GIVEN THE
THICKER CLOUD COVER SOUTH, WE EDGED THE MAX TEMPS LOWER. OUR MAX
TEMPS ACROSS OUR CWA ARE FAIRLY UNIFORM OUTSIDE OF THE HIGHER
TERRAIN. WAL AND IAD FULL SUN SUPPORT MID 90S, BUT THE AIR MASS IS
CHILLING AND THE CLOUDS SHOULD PUT A FURTHER DAMPER ON MAX TEMPS.
THE ECHOES ARE ASSOCIATED WITH THE FIRST SHORT WAVE, THE SECOND
SHORT WAVE FARTHER WEST IN THE OHIO VALLEY IS NOT GENERATING ANY,
SO WE DID CUT OFF OUR SPRINKLE CHANCES EARLY IN THE AFTERNOON WITH
THE FIRST SHORT WAVE.
A CDFNT CLEARED THE REGION AND WILL STALL TO THE SOUTH. HIGH
PRESSURE WILL BUILD IN BEHIND THE FRONT. DRIER AIR WILL MAKE ITS
WAY IN BY AFTN AND DEW POINTS WILL DROP FROM WHERE THEY CURRENTLY
HAVE BEEN, THROUGH THE 60S AND WILL END UP AROUND 60 IN MANY
LOCATIONS BY EVENING, WITH LOWER 60S ACROSS THE S CLOSER TO THE
FRONT. THIS WILL MAKE TODAY A MUCH MORE COMFORTABLE DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
NOT MUCH DIFFERENT TONIGHT. A GENLY DRY NIGHT WITH HIGH PRESSURE IN
CONTROL. AGAIN, A SHOWER CAN NOT BE RULED OUT OVER THE LWR
DELMARVA, BUT IT WILL BE MUCH MORE COMFORTABLE.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
A RATHER AMPLIFIED UPPER PATTERN FOR SUMMER CONTINUES WITH A DEEP
LOW PRESSURE SYSTEM ACROSS CANADA AND HIGH PRESSURE BANKED ACROSS
THE SOUTH. THE FRONT THE AFFECTED THE AREA FRIDAY WILL REMAIN TO THE
SOUTH AND A WAVE OF LOW PRESSURE WILL DEVELOP ALONG IT AND MOVE OFF
THE EAST COAST LATER SUNDAY INTO EARLY MONDAY. THIS WILL LEAD TO
SOME SLGT CHC OR LOW CHC POPS ACROSS SRN NJ AND THE DELMARVA FOR SUN
INTO SUN NIGHT. A WEAK S/W MOVING THRU MONDAY WILL LEAD TO A
CONTINUATION OF SLGT CHC POPS FOR THAT PERIOD. TEMPERATURES FOR THE
SUN-TUE PERIOD WILL MOSTLY BE NEAR NORMAL WITH HIGHS IN THE LOW TO
MID 80S AND LOWS MOSTLY IN THE 60S.
HIGH PRESSURE WILL BUILD OUT OF CANADA AND CAUSE A COLD FRONT TO
STRENGTHEN AND PUSH THROUGH THE AREA TUESDAY. THIS WILL PROLONG THE
CHCS FOR SHOWERS/SCT TSTMS FOR TUE AND INTO EARLY WED (SOUTH/EAST).
AS THIS HIGH BUILDS IN WED-FRI...A PERIOD OF DRY WEATHER AND BELOW
NORMAL TEMPERATURES IS EXPECTED. HIGHS FOR WED-FRI WILL BE MOSTLY IN
THE 70S ACROSS THE AREA WITH OVERNIGHT LOWS MID 50S TO LOW 60S.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
VFR CONDS ARE EXPECTED FOR THE TAF PD. DRIER AIR WILL BE MOVG IN
BEHIND A CFP. A GENL W TO NW FLOW IS EXPECTED WITH WIND 10 KTS OR
LESS DURG THE DAY AND DROPPING TO 5 KTS OR LESS AFTER SUNSET.
OUTLOOK...
SUN THRU MON NIGHT...MOSTLY VFR WITH SCT SHOWERS/TSTMS.
TUE AND TUE NIGHT...MOSTLY VFR BUT RESTRICTIONS POSSIBLE IN
SHOWERS/TSTMS.
WED...MOSTLY VFR.
&&
.MARINE...
RELATIVELY QUIET CONDS ON THE AREA WATERS WITH W TO NW FLOW AROUND
10 KTS AND SEAS DECREASING. SEAS WILL END UP IN THE 2 TO 3 FT RANGE
AFTER BEING AS HIGH AS 4 FT THIS MRNG. A CDFNT WILL CROSS THE AREA
WATERS LATER THIS MRNG AND THE WIND WILL SHIFT TO W THEN NW. NO
HEADLINES ARE ANTICIPATED THRU THE NR AND SHORT TERM PDS.
OUTLOOK...
SUB-SCA CONDITIONS ARE EXPECTED THROUGH THE LONGER TERM PART OF
THE FCST. A FEW SHOWERS/TSTMS ARE POSSIBLE SUN-TUE NIGHT.
&&
.CLIMATE...
A PHLRERGED WAS ISSUED EARLIER FOR A RECORD PCPN AT GEORGETOWN,
DE. MOUNT POCONO, PA ALSO SET A PCPN RECORD FRIDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...O`HARA
NEAR TERM...GIGI/NIERENBERG
SHORT TERM...NIERENBERG
LONG TERM...O`HARA
AVIATION...NIERENBERG/O`HARA
MARINE...NIERENBERG/O`HARA
CLIMATE...O`O`HARA
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
930 PM EDT SUN AUG 11 2013
.DISCUSSION...
HIGH PRES RIDGE EXTENDING FROM THE FL BIG BEND OUT TO BERMUDA WILL
GENERATE A LIGHT BUT DEEP SERLY BREEZE ACRS CENTRAL FL OVERNIGHT.
AIRMASS REMAINS UNSEASONABLY DRY WITH LATEST RUC ANALYSIS SHOWING
H100-H70 MEAN RH VALUES AOB 50PCT OVER MOST OF THE CWA...H85-H50
MEAN RH AOB 35PCT. NO SIG MOISTURE...NO PRECIP...`NUFF SAID.
OTHER THAN A FEW SCRAPS OF CI N OF THE CAPE...SKIES WILL BE CLEAR
OVERNIGHT. GOOD RADIATIONAL COOLING CONDITIONS WILL ALLOW WINDS TO
BECOME LIGHT AFT MIDNIGHT. THIS...IN TURN...WILL ALLOW MIN TEMPS TO
FALL TO WITHIN A DEG OR TWO OF THE SFC DEWPOINTS...WHICH LATEST OBS
SHOW ARE IN THE L/M70S AREAWIDE.
NO UPDATES NECESSARY THIS EVNG.
&&
.AVIATION...
THRU 12/18Z...VFR ALL SITES.
&&
.MARINE...
ATLC RIDGE AXIS DRAPED OVER THE NORTH FL PENINSULA WILL GENERATE A
LIGHT TO GENTLE SERLY BREEZE ACRS THE LCL ATLC OVERNIGHT. SEAS
2-3FT...MAINLY IN A LONG PD ERLY SWELL. NO SIG CHANGES WITH THE EVNG
UPDATE.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
BRAGAW
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
920 PM EDT SUN AUG 11 2013
.UPDATE...
01Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A LARGE EAST-WEST ORIENTED
UPPER LEVEL RIDGE IN PLACE OVER THE FLORIDA PENINSULA. THIS RIDGE
AND THE RESULTING DRY AIR/SYNOPTIC SUPPRESSION RESULTED IN JUST
ABOUT AS QUIET A DAY IN TERMS OF CONVECTION ACROSS THE FLORIDA
PENINSULA AS WE WILL SEE IN MID-AUGUST. THE LACK OF STORMS AND LARGE
SCALE SUBSIDENCE ALLOWED TEMPS AWAY FROM THE "COOLING" INFLUENCE OF
THE SEA-BREEZE TO REACH THE MIDDLE 90S. THE INFLUENCE OF THE UPPER
RIDGE CAN BE CLEARLY SEEN IN THE EVENING 00Z KTBW SOUNDING PROFILE
WHICH IS HIGHLIGHTED BY A WELL-DEFINED SUBSIDENCE INVERSION ABOVE
800MB.
REST OF TONIGHT...EAST COAST AND WEST COAST SEA-BREEZE BOUNDARIES
ARE COLLIDING (AS OF 915 PM EDT) ALONG THE I-75 CORRIDOR. JUST THE
OUTSIDE CHANCE OF A VERY ISOLATED SHOWER OR STORM THROUGH 11 PM
RESULTING FROM THIS COLLISION...BUT OTHERWISE DRY CONDITIONS WILL
CONTINUE FOR THE REMAINDER OF THE OVERNIGHT.
ON MONDAY...OVERALL SYNOPTIC PATTERN WILL STILL BE
SIMILAR...ALTHOUGH THE UPPER RIDGE WILL HAVE WEAKENED SLIGHTLY.
RAINFALL CHANCES FOR MOST SPOTS WILL REMAIN BELOW SEASONAL NORMALS
FOR THE FIRST DAY OF THE NEW WORK WEEK...HOWEVER THINK...UNLIKE
TODAY...WE WILL SEE A FEW STORMS BECOME ESTABLISHED LATE
AFTERNOON/EARLY EVENING. BEST CHANCES FOR ANY ISOLATED CONVECTION
SHOULD BE NORTH OF I-4 WHERE MODELS AGREE THERE WILL BE A TOUCH MORE
COLUMN MOISTURE TO WORK WITH.
THE UPPER RIDGE WILL CONTINUE TO WEAKEN/BREAK DOWN INTO THE MIDDLE
OF THE WEEK WITH MORE SEASONAL COVERAGES OF AFTERNOON/EVENING
STORMS RETURNING TO THE FORECAST.
&&
.AVIATION...
CONTINUED ANOMALOUS WEATHER OVER THE PENINSULA WITH NO SIGNIFICANT
TSTM ACTIVITY TONIGHT AND MONDAY.
&&
.MARINE...
HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE
UPCOMING WORK WEEK...WITH WINDS AND SEAS REMAINING BELOW HEADLINE
THRESHOLDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 78 94 78 93 / 20 20 20 30
FMY 76 95 76 93 / 20 20 20 30
GIF 75 95 75 95 / 10 20 10 30
SRQ 76 92 77 90 / 20 20 20 30
BKV 72 95 73 95 / 20 30 20 30
SPG 80 92 81 93 / 20 20 20 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...PAXTON
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
731 PM EDT SUN AUG 11 2013
.UPDATE...
HIGH PRESSURE IS SITUATED ACROSS THE FLORIDA PANHANDLE THIS
EVENING. A LEE TROUGH IS DEVELOPED ALONG THE TAIL END OF THE
APPALACHIANS. CONVECTION REMAINS ACROSS THE NORTHERN CWFA THIS
EVENING. ADDITIONAL ACTIVITY HAS FORMED ACROSS CENTRAL/SOUTHERN TN
ALONG AN OLD OUTFLOW BOUNDARY.
LATEST RUNS OF THE HRRR SHOW THE ACTIVITY OVER TN DIMINISHING WITH
THE LOSS OF HEATING. IN ADDITION...THE STORMS OVER NORTHERN GA
SHOULD BEGIN TO DIMINISH WITH SUNSET. HAVE RE-ADJUSTED POPS TO
REFLECT THE LATEST TRENDS. ALSO MADE SOME TWEAKS TO THE HOURLY
TEMP/DEW GRIDS.
NLISTEMAA
&&
.PREV DISCUSSION... /ISSUED 350 PM EDT SUN AUG 11 2013/
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
SHORT RANGE MODELS SHOW LITTLE CHANGE IN THE OVERALL PATTERN THROUGH
THE SHORT TERM... WITH AN ACTIVE WESTERLY FLOW ALOFT PERSISTING.
THIS WILL HELP HOLD A WEAK FRONTAL BOUNDARY NORTH OF THE STATE AND
ACROSS THE TN VALLEY... ALL SUGGESTING THE GREATEST RAIN CHANCES
WILL REMAIN ACROSS NORTH GA AND AREAS NORTHWARD THIS AFTERNOON...
EVENING AND AGAIN ON MONDAY.
REGIONAL RADARS SHOW SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
ONGOING ACROSS FAR NORTH GA THIS AFTERNOON... AND THIS ACTIVITY WILL
PERSIST THROUGH MID EVENING BEFORE DISSIPATING WITH LOSS OF DAYTIME
HEATING. REDEVELOPMENT ALONG OUTFLOWS COULD ALLOW A FEW STORMS TO
PUSH DOWN INTO THE ATLANTA METRO AREA LATER THIS AFTERNOON OR
EVENING... BUT OVERALL TRENDS SUGGEST MOST CONVECTIVE ACTIVITY WILL
REMAIN JUST NORTH OF ATLANTA THROUGH THE EVENING. THIS COULD CHANGE
SLIGHTLY ON MONDAY AS INCREASING UPPER SUPPORT SHOULD HELP SPREAD
CONVECTION FURTHER SOUTH MONDAY AFTERNOON/EVENING. WILL CONTINUE TO
SHOW THE GREATER RAIN CHANCES ACROSS NORTH GA ON MONDAY... BUT AMPLE
MOISTURE /1.8+PW`S/ AND MODERATE INSTABILITIES /2500-3000 CAPE/ WITH
GREATER UPPER SUPPORT SUGGEST SCATTERED STORMS COULD DEVELOP JUST
ABOUT ANYWHERE MONDAY AFTERNOON. ALTHOUGH CANNOT RULE OUT AN
ISOLATED PULSE SEVERE STORM DURING MAX HEATING EACH DAY... THE MAIN
STORM THREAT CONTINUES TO BE LOCALLY HEAVY RAIN AND BRIEF FLOODING
AS STORMS WILL BE SLOW MOVING WITH A TENDENCY TO TRAIN FROM WEST TO
EAST ACROSS THE SAME AREAS. WIDESPREAD RAINFALL TOTALS FROM THIS
AFTERNOON THROUGH MONDAY AFTERNOON SHOULD BE GENERALLY AN INCH OR
LESS ACROSS NORTH GA...WITH SOME ISOLATED HIGHER AMOUNTS OF 2-3
INCHES LIKELY. EXPECT GENERALLY A QUARTER INCH OR LESS ELSEWHERE.
AS FOR TEMPS... LEANED TOWARD A BLEND BETWEEN PERSISTENCE AND THE
SLIGHTLY WARMER MAV THROUGH THE SHORT TERM.
39
LONG TERM /TUESDAY THROUGH SUNDAY/...
LITTLE CHANGE IN LONG TERM PATTERN. ZONAL FLOW CONTINUES INTO THE
BEGINNING OF THE EXTENDED FORECAST BUT GRADUALLY TRANSITIONS TO AN
UPPER TROUGH BY WED/THU. THE CWA REMAINS IN A MOIST AIR MASS WITH
WEAK IMPULSES IN THE UPPER FLOW. MODELS PERSISTENT IN SHOWING
A LITTLE DRIER AIR PUSHING INTO NORTH GA TOWARD THE END OF THE
WEEK WITH A WEDGE LIKE PATTERN SETTING UP. THIS WILL DEPEND UPON HOW
FAR SOUTH THE SURFACE BOUNDARY SINKS THOROUGH THE STATE. WILL CONTINUE
WITH PERSISTENCE AND KEEP POPS MENTIONED THROUGH DAY 7...WITH SOME
LOWERING OF POPS ACROSS THE NORTH BY THE END OF THE FORECAST. IF
SURFACE BOUNDARY PUSHES INTO CENTRAL GA AND THE EASTERLY FLOW SETS
UP...TEMPERATURES BY LATE WEEK SHOULD BE SEVERAL DEGREES COOLER
THAN SEASONAL NORMS.
01
&&
.AVIATION...
00Z UPDATE...
CONVECTION REMAINS JUST NORTH OF THE ATL TERMINAL THIS EVENING.
ACTIVITY SHOULD DIMINISH WITH THE LOSS OF HEATING AS IN PREVIOUS
NIGHTS. DIURNAL CU/CONVECTION EXPECTED AGAIN TOMORROW. WINDS WILL
REMAIN LIGHT AND WESTERLY.
//ATL CONFIDENCE...00Z UPDATE...
HIGH CONFIDENCE ALL ELEMENTS.
NLISTEMAA
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 70 92 72 90 / 20 50 40 60
ATLANTA 72 89 73 88 / 30 50 40 60
BLAIRSVILLE 67 81 68 82 / 30 60 40 60
CARTERSVILLE 69 89 70 87 / 30 60 40 60
COLUMBUS 73 93 73 91 / 20 50 30 60
GAINESVILLE 71 88 71 87 / 30 50 30 60
MACON 72 94 71 93 / 20 40 30 60
ROME 71 90 70 88 / 30 60 40 60
PEACHTREE CITY 70 89 70 88 / 30 50 40 60
VIDALIA 74 95 74 94 / 20 40 30 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ATWELL
LONG TERM....ATWELL
AVIATION...ATWELL
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1024 PM CDT SUN AUG 11 2013
.DISCUSSION...
837 PM CDT
SHOWERS WHICH HAVE PERSISTED NEAR THE I-88/I-90 CORRIDORS FOR MUCH
OF THE EVENING HAVE BEGUN TO SHOW A WEAKENING TREND...AND SHOULD
CONTINUE TO DISSIPATE AS THE SURFACE COOLS AND WHAT MEAGER
INSTABILITY THAT WAS THERE WEAKENS. THIS WILL ALLOW FOR A SHORT
BREAK IN PRECIPITATION TONIGHT BEFORE STRONGER SHOWERS AND
THUNDERSTORMS ARRIVE LATER. NO MAJOR CHANGES IN THINKING FOR THE
OVERNIGHT HOURS AS AN AREA OF THUNDERSTORMS CURRENTLY OVER IOWA IS
EXPECTED TO CONTINUE TO DEVELOP EASTWARD. THUNDERSTORMS SHOULD
MOVE OVER MAINLY THE NORTHERN TIER OR TWO OF COUNTIES ON THE NOSE
OF A VERY MODEST 25-30KT LOW/MID LEVEL WIND MAX THAT WILL INCREASE
MOISTURE CONVERGENCE WITHIN A NARROW CORRIDOR OF MUCAPE OF AROUND
700 J/KG. IT APPEARS THE BEST TIMING WILL BE FOR STORMS TO
INCREASE IN COVERAGE OVER THE WESTERN CWA AROUND OR JUST BEFORE
MIDNIGHT TONIGHT...THEN THE HEAVIEST PRECIP SHOULD BEGIN TO SHIFT
EAST OF THE CWA IN THE PREDAWN HOURS MONDAY.
DEUBELBEISS
//PREV DISCUSSION...
310 PM CDT
MAIN FORECAST CONCERNS FOCUS ON SHOWER/THUNDERSTORM POTENTIAL
THROUGH THE FIRST 24-36 HOURS OF THE PACKAGE...WITH THE APPROACH AND
PASSAGE OF SLOW MOVING COLD FRONT AND WEAK FRONTAL WAVE TONIGHT
THROUGH MONDAY. SURFACE HIGH PRESSURE WILL THEN SPREAD ACROSS THE
REGION MID-LATE WEEK...MAKING FOR A RELATIVELY QUIET PERIOD OF
AUGUST WEATHER...WITH TEMPERATURES AVERAGING COOLER THAN NORMAL.
THE MAIN FEATURES ON THE LOCAL WEATHER MAP THIS AFTERNOON CONSIST OF
AN AREA OF HIGH PRESSURE OVER CENTRAL ILLINOIS...WHICH CONTINUES TO
WEAKEN AND DRIFT SOUTHEAST OF THE LOCAL CWA. OF MORE INTEREST IS A
WEST-EAST SURFACE FRONTAL BOUNDARY...WHICH STRETCHES FROM THE HIGH
PLAINS OF EASTERN WYOMING...ACROSS NEBRASKA AND NORTHERN IOWA INTO
FAR NORTHWEST ILLINOIS PER 19Z ANALYSIS. WEAKENING AREAS OF
PRECIPITATION HAVE CONTINUED TO WORK EAST ACROSS SOUTHERN
MN/NORTHERN IA AND SOUTHERN WI DURING THE DAY...IN RESPONSE TO WEAK
BUT PERSISTENT WEST-SOUTHWEST LOW LEVEL FLOW INDUCED BY SHORT WAVE
PROPAGATING ACROSS THE UPPER MISSISSIPPI VALLEY...AND ASSOCIATED
WARM/MOIST ADVECTION ACROSS THE LOW LEVEL BAROCLINIC ZONE. WHILE
PRECIP IN THE WFO LOT CWA HAS BEEN LIMITED TO MAINLY A FEW SPRINKLES
ALONG THE IL/WI BORDER...SPC RAP MESOANALYSIS AND RAP/WRF FORECAST
SOUNDINGS CONTINUE TO DEPICT SOME WEAK INSTABILITY DEVELOPING OVER
NORTHWEST/NORTH CENTRAL IL NEAR THE SURFACE FRONT DURING THE LATE
AFTERNOON HOURS. 250-500 J/KG MUCAPE ADMITTEDLY WEAK...THOUGH
PRESENCE OF PERSISTENT WEAK CONVERGENCE/ASCENT ALONG THE BAROCLINIC
BOUNDARY DOES PRESENT SOME POTENTIAL FOR ADDITIONAL SHRA/ISOLATED
TSRA DEVELOPMENT...WITH SOME INCREASE IN CU DEVELOPMENT NOTED IN
RECENT GOES VIS IMAGERY. HAVE MAINTAINED AN ISOLATES SHRA/TSRA
MENTION AFTER 4-5 PM ACROSS PARTS OF NORTH CENTRAL ILLINOIS ROUGHLY
NORTH OF THE ROCK AND WEST OF THE FOX RIVERS.
THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THEN APPEARS TO INCREASE
FROM MID/LATE-EVENING INTO THE OVERNIGHT HOURS FROM NORTHEAST IOWA
INTO SOUTHERN WISCONSIN...AND ADJACENT PORTIONS OF NORTHERN
ILLINOIS. THIS INCREASE IS IN RESPONSE TO WEAK LARGE SCALE HEIGHT
FALLS INDICATIVE OF ASCENT WITH ADDITIONAL SHORT WAVE ENERGY
APPROACHING FROM UPSTREAM...AND INCREASING MOISTURE TRANSPORT ALONG
LOW LEVEL BAROCLINIC ZONE WITH 925-850MB WEST-SOUTHWEST 20-25 KT
FLOW AS INDICATED BY COMPLEMENTARY RAP/WRF-NAM PROGS. UPPER LEVEL
DIVERGENCE IN RIGHT ENTRANCE REGION TO UPPER LEVEL JET STREAK MAY
ALSO AID IN DEVELOPMENT FROM NORTHEAST IA INTO SOUTHWEST WI EARLIER
IN THE NIGHT...BEFORE IT TRANSLATES FARTHER EAST ACROSS MICHIGAN
LATE. WEAK SURFACE WAVE ALONG FRONT CURRENTLY OVER NORTHEAST
NEBRASKA IS PROGGED TO MOVE ACROSS SOUTHERN WI IN THE PROCESS.
WITH THE LOW LEVEL JET GRADUALLY VEERING FROM WEST-SOUTHWEST TO WEST
THROUGH THE NIGHT...THIS SHOULD HELP FOCUS FOR PRECIP SHIFT FROM
NORTHEAST IA/SOUTHWEST WI EARLY...TO SOUTHWESTERN MICHIGAN BY
SUNRISE. ALL GUIDANCE POINTS TO A FAIRLY LIMITED PORTION OF NORTHERN
IL BEING AFFECTED...PRIMARILY NORTH OF THE INTERSTATE 88 CORRIDOR.
WHILE INSTABILITY IS NOT PARTICULARLY IMPRESSIVE...UPSTREAM PWAT
VALUES ARE ROUGHLY 1.25-1.50 INCHES AND WESTERLY LOW LEVEL FLOW
MAY SUPPORT SLOW EASTWARD TRANSLATION OF RESULTING CELLS. THIS COULD
PRODUCE SOME LOCALLY HEAVY RAINFALL IF TRAINING WERE TO OCCUR.
THE TRAILING COLD FRONT IT THEN PROGGED TO PUSH SLOWLY SOUTHEAST
ACROSS THE FORECAST AREA ON MONDAY...AS THE WEAK LOW PULLS AWAY
ACROSS LOWER MICHIGAN AND DEEPER FLOW OVER THE UPPER MIDWEST BECOMES
NORTHWESTERLY WITH DIGGING UPPER TROUGH. ADDITIONAL SCATTERED SHOWER
AND THUNDERSTORM DEVELOPMENT IS POSSIBLE ALONG/AHEAD OF THE FRONT...
WITH THE GREATEST POTENTIAL ACROSS THE SOUTHEAST HALF OF THE CWA
WHERE THE FRONT WILL BE DURING THE BETTER DIURNAL INSTABILITY.
INCREASE IN MID-LEVEL FLOW ACROSS THE REGION ON MONDAY WILL LIKELY
SUPPORT A GREATER CONDITIONAL MARGINAL SEVERE WIND/HAIL THREAT
ACROSS THE SOUTHEAST COUNTIES AND AREAS EAST BY AFTERNOON.
UPPER TROUGH CONTINUES TO DIG ACROSS THE NORTHEAST CONUS INTO MONDAY
NIGHT...WITH A SECONDARY PUSH OF COOLER DRIER AIR FROM THE NORTH
HELPING TO SHOVE THE COLD FRONT OUT OF THE CWA OVERNIGHT...AND COOL
HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE AREA TUESDAY-WEDNESDAY.
WITH THE MAIN UPPER TROUGH AXIS REMAINING OFF TO THE EAST OF THE
AREA...AND UPPER RIDGE TO THE WEST ACROSS ROCKIES...A PERIOD OF
FAIRLY QUIET AND COOLER THAN AVERAGE WEATHER IS ANTICIPATED. LOW
LEVEL THERMAL GUIDANCE SUGGESTS AFTERNOON HIGHS IN THE MID-UPPER 70S
DURING THE MID-WEEK PERIOD...GRADUALLY MODERATING TO THE UPPER 70S
AND LOWER 80S LATE WEEK AND NEXT WEEKEND. SOME INDICATION IN THE
LONGER RANGE GUIDANCE THAT AN UPPER LOW WILL DEVELOP ACROSS THE
LOWER OHIO OR TENNESSEE VALLEYS LATE IN THE WEEKEND...WITH BOTH THE
ECMWF AND GFS RUNS SUGGESTING THE POTENTIAL TO WRAP A LITTLE
MOISTURE INTO THE AREA FROM THE SOUTHEAST. OTHERWISE...APPEARS
MAINLY DRY THROUGH THE PERIOD BEYOND TOMORROW.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* ISOLATED LIGHT SHOWERS...MAINLY NORTH OF ORD/MDW THRU ABOUT 09Z
* MORE WIDESPREAD SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS FAR
NORTHERN IL AFTER 06-09Z.
* COLD FRONT PASSAGE AROUND 18Z MONDAY WITH WINDS BECOMING NNW THEN
NNE.
ALLSOPP
//DISCUSSION...UPDATED 00Z...
RADAR INDICATING A GENERAL WEAKENING TREND IN THE SCATTERED
SHOWERS OVER NORTHERN IL EARLY THIS EVENING. KEPT A VCSH IN NORTHERN
IL TAFS FOR A COUPLE HOURS BUT SHOWERS MAY BE ABOUT DONE BY 00Z OR
SHORTLY AFTER. GENERALLY WSW WINDS AROUND 5-8 KTS EXPECTED OVERNIGHT
BUT WINDS MAY BE VARIABLE AROUND ANY SHOWERS.
THE MAIN FORECAST CONCERN FOR OVERNIGHT IS A BAND OF SHOWERS AND
THUNDERSTORMS CURRENTLY FROM NEBRASKA TO NORTHEAST IOWA. VARIOUS
SHORT TERM MODEL GUIDANCE SEEM TO BE TAKING THIS ACROSS NORTHERN
IL LATER THIS EVENING INTO MONDAY MORNING...THOUGH SOME GUIDANCE
KEEPS THE BULK OF IT NORTH OF CHICAGO INTO SOUTHERN WI AND FAR
NORTHERN IL. FOR THIS FORECAST CYCLE KEPT A PERIOD OF SHOWERS IN
THE TAFS BUT ONLY ENOUGH CONFIDENCE TO CARRY A VCTS FOR THUNDER.
SHOWERS AND ISOLATED THUNDER MAY BE ON A DIURNAL DIMINISHING
TREND MONDAY MORNING BEFORE REDEVELOPING SOUTH OF THE TERMINALS
MONDAY AFTERNOON. STILL A LOT OF UNCERTAINTY ON THE SHOWERS AND
HOW MUCH THUNDER WILL OCCUR TONIGHT AND MONDAY MORNING.
COLD FRONT SHOULD PASS THROUGH NORTHERN IL LATE MONDAY MORNING
INTO EARLY AFTERNOON. THIS WILL INITIALLY TURN WINDS NW BUT EXPECT
LAKE BREEZE WILL TURN WINDS NE AT ORD AND MDW BY MID TO LATE
AFTERNOON.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* HIGH CONFIDENCE IN WINDS REMAINING LESS THAN 10 KTS OVERNIGHT
BUT SOME VARIABILITY IN DIRECTION EXPECTED
* MEDIUM TO HIGH CONFIDENCE IN TIMING OF COLD FRONT/WIND SHIFT
MONDAY AND LAKE BREEZE DEVELOPING LATE MONDAY.
* MEDIUM CONFIDENCE IN TIMING COVERAGE OF SHOWERS AT RFD AND ORD.
LOW CONFIDENCE IN OCCURRENCE OF THUNDER.
* LOW CONFIDENCE IN SHOWERS REACHING AS FAR SOUTH AS DPA AND MDW.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...VFR. NO SIG WX.
ALLSOPP
&&
.MARINE...
330 PM CDT
AS HIGH PRESSURE CENTERED OVER THE CENTRAL GREAT LAKES SHIFTS
SOUTHEAST TOWARDS THE OHIO VALLEY TONIGHT...A GENERAL SOUTHERLY
DIRECTION CAN BE EXPECTED ACROSS THE LAKE. ALTHOUGH...A WEAK
TROUGH OF LOW PRESSURE WILL MOVE EAST THROUGH ONTARIO AND THE
NORTHERN GREAT LAKES WITH WINDS THEN EXPECTED TO BEGIN SHIFTING TO
THE WEST LATE TONIGHT. AS THIS TROUGH EXITS TO THE EAST AND HIGH
PRESSURE BUILDS SOUTH OUT OF CANADA INTO THE NORTHERN PLAINS
MONDAY AND MONDAY NIGHT...WINDS WILL TURN MORE NORTHERLY ON MONDAY
WHILE INCREASING. NORTHERLY WINDS AND WAVES WILL CONTINUE TO
INCREASE/BUILD MONDAY NIGHT INTO TUESDAY...WITH WAVES HAZARDOUS TO
SMALL CRAFT POSSIBLE ACROSS BOTH THE ILLINOIS AND INDIANA
NEARSHORE WATERS TUESDAY/TUESDAY NIGHT. WINDS AND WAVES WILL BEGIN
TO DIMINISH LATER TUESDAY NIGHT INTO WEDNESDAY...AS HIGH PRESSURE
SETTLES BACK IN.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
841 PM CDT SUN AUG 11 2013
.DISCUSSION...
837 PM CDT
SHOWERS WHICH HAVE PERSISTED NEAR THE I-88/I-90 CORRIDORS FOR MUCH
OF THE EVENING HAVE BEGUN TO SHOW A WEAKENING TREND...AND SHOULD
CONTINUE TO DISSIPATE AS THE SURFACE COOLS AND WHAT MEAGER
INSTABILITY THAT WAS THERE WEAKENS. THIS WILL ALLOW FOR A SHORT
BREAK IN PRECIPITATION TONIGHT BEFORE STRONGER SHOWERS AND
THUNDERSTORMS ARRIVE LATER. NO MAJOR CHANGES IN THINKING FOR THE
OVERNIGHT HOURS AS AN AREA OF THUNDERSTORMS CURRENTLY OVER IOWA IS
EXPECTED TO CONTINUE TO DEVELOP EASTWARD. THUNDERSTORMS SHOULD
MOVE OVER MAINLY THE NORTHERN TIER OR TWO OF COUNTIES ON THE NOSE
OF A VERY MODEST 25-30KT LOW/MID LEVEL WIND MAX THAT WILL INCREASE
MOISTURE CONVERGENCE WITHIN A NARROW CORRIDOR OF MUCAPE OF AROUND
700 J/KG. IT APPEARS THE BEST TIMING WILL BE FOR STORMS TO
INCREASE IN COVERAGE OVER THE WESTERN CWA AROUND OR JUST BEFORE
MIDNIGHT TONIGHT...THEN THE HEAVIEST PRECIP SHOULD BEGIN TO SHIFT
EAST OF THE CWA IN THE PREDAWN HOURS MONDAY.
DEUBELBEISS
&&
.PREV DISCUSSION...
310 PM CDT
MAIN FORECAST CONCERNS FOCUS ON SHOWER/THUNDERSTORM POTENTIAL
THROUGH THE FIRST 24-36 HOURS OF THE PACKAGE...WITH THE APPROACH AND
PASSAGE OF SLOW MOVING COLD FRONT AND WEAK FRONTAL WAVE TONIGHT
THROUGH MONDAY. SURFACE HIGH PRESSURE WILL THEN SPREAD ACROSS THE
REGION MID-LATE WEEK...MAKING FOR A RELATIVELY QUIET PERIOD OF
AUGUST WEATHER...WITH TEMPERATURES AVERAGING COOLER THAN NORMAL.
THE MAIN FEATURES ON THE LOCAL WEATHER MAP THIS AFTERNOON CONSIST OF
AN AREA OF HIGH PRESSURE OVER CENTRAL ILLINOIS...WHICH CONTINUES TO
WEAKEN AND DRIFT SOUTHEAST OF THE LOCAL CWA. OF MORE INTEREST IS A
WEST-EAST SURFACE FRONTAL BOUNDARY...WHICH STRETCHES FROM THE HIGH
PLAINS OF EASTERN WYOMING...ACROSS NEBRASKA AND NORTHERN IOWA INTO
FAR NORTHWEST ILLINOIS PER 19Z ANALYSIS. WEAKENING AREAS OF
PRECIPITATION HAVE CONTINUED TO WORK EAST ACROSS SOUTHERN
MN/NORTHERN IA AND SOUTHERN WI DURING THE DAY...IN RESPONSE TO WEAK
BUT PERSISTENT WEST-SOUTHWEST LOW LEVEL FLOW INDUCED BY SHORT WAVE
PROPAGATING ACROSS THE UPPER MISSISSIPPI VALLEY...AND ASSOCIATED
WARM/MOIST ADVECTION ACROSS THE LOW LEVEL BAROCLINIC ZONE. WHILE
PRECIP IN THE WFO LOT CWA HAS BEEN LIMITED TO MAINLY A FEW SPRINKLES
ALONG THE IL/WI BORDER...SPC RAP MESOANALYSIS AND RAP/WRF FORECAST
SOUNDINGS CONTINUE TO DEPICT SOME WEAK INSTABILITY DEVELOPING OVER
NORTHWEST/NORTH CENTRAL IL NEAR THE SURFACE FRONT DURING THE LATE
AFTERNOON HOURS. 250-500 J/KG MUCAPE ADMITTEDLY WEAK...THOUGH
PRESENCE OF PERSISTENT WEAK CONVERGENCE/ASCENT ALONG THE BAROCLINIC
BOUNDARY DOES PRESENT SOME POTENTIAL FOR ADDITIONAL SHRA/ISOLATED
TSRA DEVELOPMENT...WITH SOME INCREASE IN CU DEVELOPMENT NOTED IN
RECENT GOES VIS IMAGERY. HAVE MAINTAINED AN ISOLATES SHRA/TSRA
MENTION AFTER 4-5 PM ACROSS PARTS OF NORTH CENTRAL ILLINOIS ROUGHLY
NORTH OF THE ROCK AND WEST OF THE FOX RIVERS.
THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THEN APPEARS TO INCREASE
FROM MID/LATE-EVENING INTO THE OVERNIGHT HOURS FROM NORTHEAST IOWA
INTO SOUTHERN WISCONSIN...AND ADJACENT PORTIONS OF NORTHERN
ILLINOIS. THIS INCREASE IS IN RESPONSE TO WEAK LARGE SCALE HEIGHT
FALLS INDICATIVE OF ASCENT WITH ADDITIONAL SHORT WAVE ENERGY
APPROACHING FROM UPSTREAM...AND INCREASING MOISTURE TRANSPORT ALONG
LOW LEVEL BAROCLINIC ZONE WITH 925-850MB WEST-SOUTHWEST 20-25 KT
FLOW AS INDICATED BY COMPLEMENTARY RAP/WRF-NAM PROGS. UPPER LEVEL
DIVERGENCE IN RIGHT ENTRANCE REGION TO UPPER LEVEL JET STREAK MAY
ALSO AID IN DEVELOPMENT FROM NORTHEAST IA INTO SOUTHWEST WI EARLIER
IN THE NIGHT...BEFORE IT TRANSLATES FARTHER EAST ACROSS MICHIGAN
LATE. WEAK SURFACE WAVE ALONG FRONT CURRENTLY OVER NORTHEAST
NEBRASKA IS PROGGED TO MOVE ACROSS SOUTHERN WI IN THE PROCESS.
WITH THE LOW LEVEL JET GRADUALLY VEERING FROM WEST-SOUTHWEST TO WEST
THROUGH THE NIGHT...THIS SHOULD HELP FOCUS FOR PRECIP SHIFT FROM
NORTHEAST IA/SOUTHWEST WI EARLY...TO SOUTHWESTERN MICHIGAN BY
SUNRISE. ALL GUIDANCE POINTS TO A FAIRLY LIMITED PORTION OF NORTHERN
IL BEING AFFECTED...PRIMARILY NORTH OF THE INTERSTATE 88 CORRIDOR.
WHILE INSTABILITY IS NOT PARTICULARLY IMPRESSIVE...UPSTREAM PWAT
VALUES ARE ROUGHLY 1.25-1.50 INCHES AND WESTERLY LOW LEVEL FLOW
MAY SUPPORT SLOW EASTWARD TRANSLATION OF RESULTING CELLS. THIS COULD
PRODUCE SOME LOCALLY HEAVY RAINFALL IF TRAINING WERE TO OCCUR.
THE TRAILING COLD FRONT IT THEN PROGGED TO PUSH SLOWLY SOUTHEAST
ACROSS THE FORECAST AREA ON MONDAY...AS THE WEAK LOW PULLS AWAY
ACROSS LOWER MICHIGAN AND DEEPER FLOW OVER THE UPPER MIDWEST BECOMES
NORTHWESTERLY WITH DIGGING UPPER TROUGH. ADDITIONAL SCATTERED SHOWER
AND THUNDERSTORM DEVELOPMENT IS POSSIBLE ALONG/AHEAD OF THE FRONT...
WITH THE GREATEST POTENTIAL ACROSS THE SOUTHEAST HALF OF THE CWA
WHERE THE FRONT WILL BE DURING THE BETTER DIURNAL INSTABILITY.
INCREASE IN MID-LEVEL FLOW ACROSS THE REGION ON MONDAY WILL LIKELY
SUPPORT A GREATER CONDITIONAL MARGINAL SEVERE WIND/HAIL THREAT
ACROSS THE SOUTHEAST COUNTIES AND AREAS EAST BY AFTERNOON.
UPPER TROUGH CONTINUES TO DIG ACROSS THE NORTHEAST CONUS INTO MONDAY
NIGHT...WITH A SECONDARY PUSH OF COOLER DRIER AIR FROM THE NORTH
HELPING TO SHOVE THE COLD FRONT OUT OF THE CWA OVERNIGHT...AND COOL
HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE AREA TUESDAY-WEDNESDAY.
WITH THE MAIN UPPER TROUGH AXIS REMAINING OFF TO THE EAST OF THE
AREA...AND UPPER RIDGE TO THE WEST ACROSS ROCKIES...A PERIOD OF
FAIRLY QUIET AND COOLER THAN AVERAGE WEATHER IS ANTICIPATED. LOW
LEVEL THERMAL GUIDANCE SUGGESTS AFTERNOON HIGHS IN THE MID-UPPER 70S
DURING THE MID-WEEK PERIOD...GRADUALLY MODERATING TO THE UPPER 70S
AND LOWER 80S LATE WEEK AND NEXT WEEKEND. SOME INDICATION IN THE
LONGER RANGE GUIDANCE THAT AN UPPER LOW WILL DEVELOP ACROSS THE
LOWER OHIO OR TENNESSEE VALLEYS LATE IN THE WEEKEND...WITH BOTH THE
ECMWF AND GFS RUNS SUGGESTING THE POTENTIAL TO WRAP A LITTLE
MOISTURE INTO THE AREA FROM THE SOUTHEAST. OTHERWISE...APPEARS
MAINLY DRY THROUGH THE PERIOD BEYOND TOMORROW.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* SHOWERS AND ISOLATED THUNDERSTORMS EXPECTED TO OVERSPREAD
NORTHERN IL LATER TONIGHT INTO MONDAY MORNING.
* SLOW MOVING COLD FRONT WILL TURN WINDS NW MONDAY AFTERNOON.
* LAKE BREEZE LIKELY BY LATE AFTERNOON MONDAY.
ALLSOPP
//DISCUSSION...UPDATED 00Z...
RADAR INDICATING A GENERAL WEAKENING TREND IN THE SCATTERED
SHOWERS OVER NORTHERN IL EARLY THIS EVENING. KEPT A VCSH IN NORTHERN
IL TAFS FOR A COUPLE HOURS BUT SHOWERS MAY BE ABOUT DONE BY 00Z OR
SHORTLY AFTER. GENERALLY WSW WINDS AROUND 5-8 KTS EXPECTED OVERNIGHT
BUT WINDS MAY BE VARIABLE AROUND ANY SHOWERS.
THE MAIN FORECAST CONCERN FOR OVERNIGHT IS A BAND OF SHOWERS AND
THUNDERSTORMS CURRENTLY FROM NEBRASKA TO NORTHEAST IOWA. VARIOUS
SHORT TERM MODEL GUIDANCE SEEM TO BE TAKING THIS ACROSS NORTHERN
IL LATER THIS EVENING INTO MONDAY MORNING...THOUGH SOME GUIDANCE
KEEPS THE BULK OF IT NORTH OF CHICAGO INTO SOUTHERN WI AND FAR
NORTHERN IL. FOR THIS FORECAST CYCLE KEPT A PERIOD OF SHOWERS IN
THE TAFS BUT ONLY ENOUGH CONFIDENCE TO CARRY A VCTS FOR THUNDER.
SHOWERS AND ISOLATED THUNDER MAY BE ON A DIURNAL DIMINISHING
TREND MONDAY MORNING BEFORE REDEVELOPING SOUTH OF THE TERMINALS
MONDAY AFTERNOON. STILL A LOT OF UNCERTAINTY ON THE SHOWERS AND
HOW MUCH THUNDER WILL OCCUR TONIGHT AND MONDAY MORNING.
COLD FRONT SHOULD PASS THROUGH NORTHERN IL LATE MONDAY MORNING
INTO EARLY AFTERNOON. THIS WILL INITIALLY TURN WINDS NW BUT EXPECT
LAKE BREEZE WILL TURN WINDS NE AT ORD AND MDW BY MID TO LATE
AFTERNOON.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW TO MEDIUM CONFIDENCE ON TIMING AND COVERAGE OF SHOWERS AND
THUNDERSTORMS LATE TONIGHT INTO MONDAY MORNING.
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST AND TIMING OF COLD FRONT
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...VFR. NO SIG WX.
ALLSOPP
&&
.MARINE...
330 PM CDT
AS HIGH PRESSURE CENTERED OVER THE CENTRAL GREAT LAKES SHIFTS
SOUTHEAST TOWARDS THE OHIO VALLEY TONIGHT...A GENERAL SOUTHERLY
DIRECTION CAN BE EXPECTED ACROSS THE LAKE. ALTHOUGH...A WEAK
TROUGH OF LOW PRESSURE WILL MOVE EAST THROUGH ONTARIO AND THE
NORTHERN GREAT LAKES WITH WINDS THEN EXPECTED TO BEGIN SHIFTING TO
THE WEST LATE TONIGHT. AS THIS TROUGH EXITS TO THE EAST AND HIGH
PRESSURE BUILDS SOUTH OUT OF CANADA INTO THE NORTHERN PLAINS
MONDAY AND MONDAY NIGHT...WINDS WILL TURN MORE NORTHERLY ON MONDAY
WHILE INCREASING. NORTHERLY WINDS AND WAVES WILL CONTINUE TO
INCREASE/BUILD MONDAY NIGHT INTO TUESDAY...WITH WAVES HAZARDOUS TO
SMALL CRAFT POSSIBLE ACROSS BOTH THE ILLINOIS AND INDIANA
NEARSHORE WATERS TUESDAY/TUESDAY NIGHT. WINDS AND WAVES WILL BEGIN
TO DIMINISH LATER TUESDAY NIGHT INTO WEDNESDAY...AS HIGH PRESSURE
SETTLES BACK IN.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
636 PM CDT SUN AUG 11 2013
.DISCUSSION...
310 PM CDT
MAIN FORECAST CONCERNS FOCUS ON SHOWER/THUNDERSTORM POTENTIAL
THROUGH THE FIRST 24-36 HOURS OF THE PACKAGE...WITH THE APPROACH AND
PASSAGE OF SLOW MOVING COLD FRONT AND WEAK FRONTAL WAVE TONIGHT
THROUGH MONDAY. SURFACE HIGH PRESSURE WILL THEN SPREAD ACROSS THE
REGION MID-LATE WEEK...MAKING FOR A RELATIVELY QUIET PERIOD OF
AUGUST WEATHER...WITH TEMPERATURES AVERAGING COOLER THAN NORMAL.
THE MAIN FEATURES ON THE LOCAL WEATHER MAP THIS AFTERNOON CONSIST OF
AN AREA OF HIGH PRESSURE OVER CENTRAL ILLINOIS...WHICH CONTINUES TO
WEAKEN AND DRIFT SOUTHEAST OF THE LOCAL CWA. OF MORE INTEREST IS A
WEST-EAST SURFACE FRONTAL BOUNDARY...WHICH STRETCHES FROM THE HIGH
PLAINS OF EASTERN WYOMING...ACROSS NEBRASKA AND NORTHERN IOWA INTO
FAR NORTHWEST ILLINOIS PER 19Z ANALYSIS. WEAKENING AREAS OF
PRECIPITATION HAVE CONTINUED TO WORK EAST ACROSS SOUTHERN
MN/NORTHERN IA AND SOUTHERN WI DURING THE DAY...IN RESPONSE TO WEAK
BUT PERSISTENT WEST-SOUTHWEST LOW LEVEL FLOW INDUCED BY SHORT WAVE
PROPAGATING ACROSS THE UPPER MISSISSIPPI VALLEY...AND ASSOCIATED
WARM/MOIST ADVECTION ACROSS THE LOW LEVEL BAROCLINIC ZONE. WHILE
PRECIP IN THE WFO LOT CWA HAS BEEN LIMITED TO MAINLY A FEW SPRINKLES
ALONG THE IL/WI BORDER...SPC RAP MESOANALYSIS AND RAP/WRF FORECAST
SOUNDINGS CONTINUE TO DEPICT SOME WEAK INSTABILITY DEVELOPING OVER
NORTHWEST/NORTH CENTRAL IL NEAR THE SURFACE FRONT DURING THE LATE
AFTERNOON HOURS. 250-500 J/KG MUCAPE ADMITTEDLY WEAK...THOUGH
PRESENCE OF PERSISTENT WEAK CONVERGENCE/ASCENT ALONG THE BAROCLINIC
BOUNDARY DOES PRESENT SOME POTENTIAL FOR ADDITIONAL SHRA/ISOLATED
TSRA DEVELOPMENT...WITH SOME INCREASE IN CU DEVELOPMENT NOTED IN
RECENT GOES VIS IMAGERY. HAVE MAINTAINED AN ISOLATES SHRA/TSRA
MENTION AFTER 4-5 PM ACROSS PARTS OF NORTH CENTRAL ILLINOIS ROUGHLY
NORTH OF THE ROCK AND WEST OF THE FOX RIVERS.
THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THEN APPEARS TO INCREASE
FROM MID/LATE-EVENING INTO THE OVERNIGHT HOURS FROM NORTHEAST IOWA
INTO SOUTHERN WISCONSIN...AND ADJACENT PORTIONS OF NORTHERN
ILLINOIS. THIS INCREASE IS IN RESPONSE TO WEAK LARGE SCALE HEIGHT
FALLS INDICATIVE OF ASCENT WITH ADDITIONAL SHORT WAVE ENERGY
APPROACHING FROM UPSTREAM...AND INCREASING MOISTURE TRANSPORT ALONG
LOW LEVEL BAROCLINIC ZONE WITH 925-850MB WEST-SOUTHWEST 20-25 KT
FLOW AS INDICATED BY COMPLEMENTARY RAP/WRF-NAM PROGS. UPPER LEVEL
DIVERGENCE IN RIGHT ENTRANCE REGION TO UPPER LEVEL JET STREAK MAY
ALSO AID IN DEVELOPMENT FROM NORTHEAST IA INTO SOUTHWEST WI EARLIER
IN THE NIGHT...BEFORE IT TRANSLATES FARTHER EAST ACROSS MICHIGAN
LATE. WEAK SURFACE WAVE ALONG FRONT CURRENTLY OVER NORTHEAST
NEBRASKA IS PROGGED TO MOVE ACROSS SOUTHERN WI IN THE PROCESS.
WITH THE LOW LEVEL JET GRADUALLY VEERING FROM WEST-SOUTHWEST TO WEST
THROUGH THE NIGHT...THIS SHOULD HELP FOCUS FOR PRECIP SHIFT FROM
NORTHEAST IA/SOUTHWEST WI EARLY...TO SOUTHWESTERN MICHIGAN BY
SUNRISE. ALL GUIDANCE POINTS TO A FAIRLY LIMITED PORTION OF NORTHERN
IL BEING AFFECTED...PRIMARILY NORTH OF THE INTERSTATE 88 CORRIDOR.
WHILE INSTABILITY IS NOT PARTICULARLY IMPRESSIVE...UPSTREAM PWAT
VALUES ARE ROUGHLY 1.25-1.50 INCHES AND WESTERLY LOW LEVEL FLOW
MAY SUPPORT SLOW EASTWARD TRANSLATION OF RESULTING CELLS. THIS COULD
PRODUCE SOME LOCALLY HEAVY RAINFALL IF TRAINING WERE TO OCCUR.
THE TRAILING COLD FRONT IT THEN PROGGED TO PUSH SLOWLY SOUTHEAST
ACROSS THE FORECAST AREA ON MONDAY...AS THE WEAK LOW PULLS AWAY
ACROSS LOWER MICHIGAN AND DEEPER FLOW OVER THE UPPER MIDWEST BECOMES
NORTHWESTERLY WITH DIGGING UPPER TROUGH. ADDITIONAL SCATTERED SHOWER
AND THUNDERSTORM DEVELOPMENT IS POSSIBLE ALONG/AHEAD OF THE FRONT...
WITH THE GREATEST POTENTIAL ACROSS THE SOUTHEAST HALF OF THE CWA
WHERE THE FRONT WILL BE DURING THE BETTER DIURNAL INSTABILITY.
INCREASE IN MID-LEVEL FLOW ACROSS THE REGION ON MONDAY WILL LIKELY
SUPPORT A GREATER CONDITIONAL MARGINAL SEVERE WIND/HAIL THREAT
ACROSS THE SOUTHEAST COUNTIES AND AREAS EAST BY AFTERNOON.
UPPER TROUGH CONTINUES TO DIG ACROSS THE NORTHEAST CONUS INTO MONDAY
NIGHT...WITH A SECONDARY PUSH OF COOLER DRIER AIR FROM THE NORTH
HELPING TO SHOVE THE COLD FRONT OUT OF THE CWA OVERNIGHT...AND COOL
HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE AREA TUESDAY-WEDNESDAY.
WITH THE MAIN UPPER TROUGH AXIS REMAINING OFF TO THE EAST OF THE
AREA...AND UPPER RIDGE TO THE WEST ACROSS ROCKIES...A PERIOD OF
FAIRLY QUIET AND COOLER THAN AVERAGE WEATHER IS ANTICIPATED. LOW
LEVEL THERMAL GUIDANCE SUGGESTS AFTERNOON HIGHS IN THE MID-UPPER 70S
DURING THE MID-WEEK PERIOD...GRADUALLY MODERATING TO THE UPPER 70S
AND LOWER 80S LATE WEEK AND NEXT WEEKEND. SOME INDICATION IN THE
LONGER RANGE GUIDANCE THAT AN UPPER LOW WILL DEVELOP ACROSS THE
LOWER OHIO OR TENNESSEE VALLEYS LATE IN THE WEEKEND...WITH BOTH THE
ECMWF AND GFS RUNS SUGGESTING THE POTENTIAL TO WRAP A LITTLE
MOISTURE INTO THE AREA FROM THE SOUTHEAST. OTHERWISE...APPEARS
MAINLY DRY THROUGH THE PERIOD BEYOND TOMORROW.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* SHOWERS AND ISOLATED THUNDERSTORMS EXPECTED TO OVERSPREAD
NORTHERN IL LATER TONIGHT INTO MONDAY MORNING.
* SLOW MOVING COLD FRONT WILL TURN WINDS NW MONDAY AFTERNOON.
* LAKE BREEZE LIKELY BY LATE AFTERNOON MONDAY.
ALLSOPP
//DISCUSSION...UPDATED 00Z...
RADAR INDICATING A GENERAL WEAKENING TREND IN THE SCATTERED
SHOWERS OVER NORTHERN IL EARLY THIS EVENING. KEPT A VCSH IN NORTHERN
IL TAFS FOR A COUPLE HOURS BUT SHOWERS MAY BE ABOUT DONE BY 00Z OR
SHORTLY AFTER. GENERALLY WSW WINDS AROUND 5-8 KTS EXPECTED OVERNIGHT
BUT WINDS MAY BE VARIABLE AROUND ANY SHOWERS.
THE MAIN FORECAST CONCERN FOR OVERNIGHT IS A BAND OF SHOWERS AND
THUNDERSTORMS CURRENTLY FROM NEBRASKA TO NORTHEAST IOWA. VARIOUS
SHORT TERM MODEL GUIDANCE SEEM TO BE TAKING THIS ACROSS NORTHERN
IL LATER THIS EVENING INTO MONDAY MORNING...THOUGH SOME GUIDANCE
KEEPS THE BULK OF IT NORTH OF CHICAGO INTO SOUTHERN WI AND FAR
NORTHERN IL. FOR THIS FORECAST CYCLE KEPT A PERIOD OF SHOWERS IN
THE TAFS BUT ONLY ENOUGH CONFIDENCE TO CARRY A VCTS FOR THUNDER.
SHOWERS AND ISOLATED THUNDER MAY BE ON A DIURNAL DIMINISHING
TREND MONDAY MORNING BEFORE REDEVELOPING SOUTH OF THE TERMINALS
MONDAY AFTERNOON. STILL A LOT OF UNCERTAINTY ON THE SHOWERS AND
HOW MUCH THUNDER WILL OCCUR TONIGHT AND MONDAY MORNING.
COLD FRONT SHOULD PASS THROUGH NORTHERN IL LATE MONDAY MORNING
INTO EARLY AFTERNOON. THIS WILL INITIALLY TURN WINDS NW BUT EXPECT
LAKE BREEZE WILL TURN WINDS NE AT ORD AND MDW BY MID TO LATE
AFTERNOON.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* LOW TO MEDIUM CONFIDENCE ON TIMING AND COVERAGE OF SHOWERS AND
THUNDERSTORMS LATE TONIGHT INTO MONDAY MORNING.
* MEDIUM TO HIGH CONFIDENCE IN WIND FORECAST AND TIMING OF COLD FRONT
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...VFR. NO SIG WX.
ALLSOPP
&&
.MARINE...
330 PM CDT
AS HIGH PRESSURE CENTERED OVER THE CENTRAL GREAT LAKES SHIFTS
SOUTHEAST TOWARDS THE OHIO VALLEY TONIGHT...A GENERAL SOUTHERLY
DIRECTION CAN BE EXPECTED ACROSS THE LAKE. ALTHOUGH...A WEAK
TROUGH OF LOW PRESSURE WILL MOVE EAST THROUGH ONTARIO AND THE
NORTHERN GREAT LAKES WITH WINDS THEN EXPECTED TO BEGIN SHIFTING TO
THE WEST LATE TONIGHT. AS THIS TROUGH EXITS TO THE EAST AND HIGH
PRESSURE BUILDS SOUTH OUT OF CANADA INTO THE NORTHERN PLAINS
MONDAY AND MONDAY NIGHT...WINDS WILL TURN MORE NORTHERLY ON MONDAY
WHILE INCREASING. NORTHERLY WINDS AND WAVES WILL CONTINUE TO
INCREASE/BUILD MONDAY NIGHT INTO TUESDAY...WITH WAVES HAZARDOUS TO
SMALL CRAFT POSSIBLE ACROSS BOTH THE ILLINOIS AND INDIANA
NEARSHORE WATERS TUESDAY/TUESDAY NIGHT. WINDS AND WAVES WILL BEGIN
TO DIMINISH LATER TUESDAY NIGHT INTO WEDNESDAY...AS HIGH PRESSURE
SETTLES BACK IN.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
254 PM CDT SAT AUG 10 2013
.DISCUSSION...
341 AM CDT
MAIN FORECAST CONCERN IS SHRA/TSRA CHANCES SUNDAY THROUGH MONDAY
EVENING. EARLY MORNING W/V IMAGERY SHOWS BROAD TROUGHING FROM
EASTERN INTO CENTRAL CANADA AND THE NORTHERN LAKES WITH RIDGING
OVER THE WESTERN CONUS AND SEVERAL WAVES CRESTING THE RIDGE OVER
THE NORTHERN ROCKIES THAT WILL PLAY A ROLE IN OUR SENSIBLE WEATHER
ON SUNDAY AND SUNDAY NIGHT AS THEY TRAVERSE DISTURBED WEST-
NORTHWEST FLOW ALOFT. AT THE SURFACE...HIGH PRESSURE WILL CENTER
OVER THE REGION TODAY...BEFORE SLOWLY SLIDING EAST SUNDAY. A COLD
FRONT WILL MOVE THROUGH THE AREA ON MONDAY.
COOLER AIR MASS WILL FILTER INTO AREA TODAY...NOTED WITH +10 AND +11
RESPECTIVELY AT 850 MB AT KMPX AND KGRB ON THE 00Z RAOBS. THE BACK
EDGE OF CIRRUS SHIELD OVER THE AREA WILL CLEAR OFF TO THE EAST OF
BY DAYBREAK OR SO...YIELDING EARLY MORNING CLEAR SKIES...BUT
GUIDANCE SHOWS MOISTURE FROM H9-H8 SEEPING IN FROM NORTH DURING
DAY...WHICH SHOULD ALLOW FOR SCATTERED TO POSSIBLY BROKEN CUMULUS BY
THE AFTERNOON AS LOW LEVEL LAPSE RATES STEEPEN. PROGGED H8 AND H9
TEMPS SUPPORTS HIGHS IN THE UPPER 70S TO POSSIBLY AROUND 80 NORTH OF
I-80 AND LOWER 80S SOUTH...WITH A FEW MID 80S READINGS. THE
EXCEPTION WILL BE THE LAKEFRONT WITH SYNOPTIC ONSHORE FLOW AND HIGHS
ONLY IN THE LOWER AND MID 70S. ALL IN ALL...IT WILL BE A SPECTACULAR
START TO THE WEEKEND. HIGH PRESSURE OVERHEAD TONIGHT AND MAINLY
CLEAR SKIES WILL RESULT IN COOL CONDITIONS IN THE LOWER AND MID 50S
OUTSIDE OF THE CHICAGO HEAT ISLAND.
THE INITIAL LEAD WAVE CURRENTLY OVER WYOMING LOOKS TO BE APPROACHING
THE REGION BUT LIKELY FOCUS NEAR OR NORTH OF THE WISCONSIN BORDER.
BY EARLY SUNDAY...A CLUSTER OF SHRA/TSRA COULD TRAVERSE THE UPPER
MISSISSIPPI VALLEY BUT IT SHOULD WEAKEN FARTHER EAST DUE TO THE
INFLUENCE OF THE HIGH PRESSURE RIDGE...LIMITED ELEVATED INSTABILITY
AND VERY WEAK LAPSE RATES ALOFT. DESPITE SOME CONSENSUS IN THE
GUIDANCE ON TRACKING THIS FEATURE TOWARD SOUTHERN WISCONSIN...HAVE
GENERALLY MAINTAINED CHANCE POPS ALONG THE BORDER. THE EXTENT OF
CLOUD COVER WITH THIS WAVE COULD LIMIT TEMPERATURES A BIT MORE THAN
CURRENTLY DEPICTED TO THE NORTH...BUT TO THE SOUTH...WHERE LESS
CLOUD COVER IS ANTICIPATED....850/925 TEMPS WILL SUPPORT HIGHS
APPROACHING THE MID 80S. GIVEN THE FACTORS THAT WILL LIKELY LEAD TO
WEAKENING OF THE PRECIP SHIELD ASSOCIATED WITH THE MID-LEVEL
WAVE...IT STILL REMAINS POSSIBLE THAT MOST OF THE AREA COULD HAVE A
DRY SUNDAY.
STRENGTHENING LOW LEVEL FLOW WILL RESULT IN DECENT MOISTURE
TRANSPORT AND CONVERGENCE FOCUSED INTO THE NORTHERN THIRD OF CWA
SUNDAY NIGHT WITH ANOTHER MID-LEVEL FEATURE WELL AHEAD OF SURFACE
COLD FRONT THAT WILL BE APPROACHING SLOWLY FROM THE NORTHWEST. EXACT
TRACK OF MIDLEVEL WAVE AND STRENGTH OF 850-925 FLOW WILL NEED TO BE
RESOLVED...BUT HAVE BUMPED UP POPS TO HIGH CHANCE RANGE ALONG THE
WISCONSIN BORDER...TAPERING TO A DRY FORECAST IN THE FAR SOUTHERN
FORECAST SOUNDINGS SHOWING SOME ELEVATED INSTABILITY AND WARM
ADVECTION PATTERN MEANS THERE WILL LIKELY BE AT LEAST EMBEDDED
THUNDER. CLOUD COVER AND WARM ADVECTION WILL RESULT IN MILDER LOW
TEMPS.
THE CONVECTIVE EVOLUTION ON SUNDAY NIGHT INTO EARLY MONDAY WILL
DICTATE TO A LARGE EXTENT WHAT HAPPENS WITH CONVECTIVE CHANCES ON
MONDAY AHEAD OF A COLD FRONT. FAVOR A SLOWER FRONTAL PASSAGE DURING
THE AFTERNOON...BUT NOT QUITE AS SLOW AS LATEST NAM. ASSUMING CLOUD
COVER DOES NOT HINDER WARMING TOO MUCH...H85 TEMPS AROUND +15 WILL
YIELD HIGHS IN THE LOWER 80S NORTH AND MID 80S SOUTH...WITH
DEWPOINTS RETURNING TO THE MID TO UPPER 60S. THIS COULD YIELD ~1500
J/KG OF CAPE PER FORECAST SOUNDINGS...WITH DECENT CONVERGENCE FROM
THE SURFACE TO 850 MB FAVORING AT LEAST SCATTERED COVERAGE OF
THUNDERSTORMS...BUT DID NOT GO HIGHER THAN MID CHANCE POPS DUE TO
UNCERTAINTY OVER CONVECTIVE EVOLUTION. IF ENOUGH INSTABILITY
DEVELOPS...WILL NEED TO WATCH FOR A SEVERE THREAT PRIMARILY IN THE
FORM OF DAMAGING WINDS...AS NORTHWESTERLY FLOW ALOFT WILL INCREASE
TO 40 KT DURING THE DAY AND STEEP LOW LEVEL LAPSE RATES WILL DEVELOP
AS WELL. HIGH FREEZING LEVELS AND MEAGER LAPSE RATES ABOVE 600 MB
WOULD LIKELY LIMIT THE HAIL THREAT.
ANY REMAINING SHRA/TSRA SHOULD CLEAR THE SOUTHERN CWA DURING THE
EVENING...WITH HIGH PRESSURE BUILDING FROM UPPER MIDWEST BEHIND COLD
FRONT. COOL NORTHERLY FLOW FROM THE SURFACE UP TO THE MID LEVELS
THANKS TO UPPER TROUGHING OVER EASTERN CANADA WILL SET UP A BELOW
NORMAL...BUT PLEASANT TUESDAY THROUGH FRIDAY PERIOD. AFTER HIGHS
LIKELY ONLY IN THE MID 70S AWAY FROM THE LAKE TUES AND
WEDS...READINGS WILL WARM SOME BY FRIDAY AS HEIGHTS BEGIN TO RISE
AND THERMAL PROFILES SLOWLY WARM. THE LAKEFRONT WILL BE KEPT COOLER
EACH DAY BY PERSISTENT ONSHORE FLOW.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* WIND REMAINING PRIMARILY NORTHEAST THIS AFTERNOON...THOUGH WITH
SOME MINOR VARIABILITY FROM NNE TO ENE AT TIMES.
* VARIABILITY IN WIND DIRECTION ALSO POSSIBLE SUNDAY...THOUGH
SHOULD GO FROM LIGHT WEST TO A LIGHT EAST-SOUTHEAST LAKE BREEZE
BY LATE AFTERNOON.
* SOME POTENTIAL FOR -RA/SHRA SUNDAY AFTERNOON...THOUGH
PROBABILITY HIGHER WEST/NORTH OF ORD/MDW TERMINALS.
RATZER
//DISCUSSION...UPDATED 18Z...
SURFACE HIGH PRESSURE WAS CENTERED NEAR KDSM AT 17Z...AND WILL
CONTINUE TO SLOWLY DRIFT SOUTHEAST ACROSS THE MIDWEST THROUGH
SUNDAY. EAST OF THE HIGH CENTER ACROSS NORTHERN IL...WINDS WERE
GENERALLY LIGHT NORTHERLY...WITH A NORTHEAST COMPONENT OFF OF THE
LAKE ACROSS THE CHICAGO METRO TERMINALS. WIND DIRECTION HAS
BECOME SOMEWHAT VARIABLE ACROSS ORD/MDW AREAS AT MIDDAY...BUT
EXPECT LAKE BREEZE PUSH THIS AFTERNOON WILL REESTABLISH A MORE
SOLID EAST-SOUTHEAST SFC WIND. WEAK PRESSURE GRADIENT TONIGHT AS
SURFACE RIDGE MOVES ACROSS THE AREA WILL ALLOW LIGHT/VARIABLE OR
CALM WINDS TO DEVELOP BY LATE EVENING AND CONTINUE INTO EARLY
SUNDAY MORNING. THE HIGH CENTER SHOULD MOVE JUST OFF TO THE SOUTH
OF THE TERMINALS SUNDAY...WHICH SHOULD RESULT IN A WEST-NORTHWEST
WIND INITIALLY...THOUGH THE WEAK GRADIENT WILL LIKELY ALLOW FOR
SOME VARIABILITY ONCE AGAIN AND AN EAST-SOUTHEAST LAKE BREEZE IN
THE MID/LATE AFTERNOON HOURS.
SCATTERED TO BROKEN DECK OF DIURNAL CU OVER AREA WILL FADE WITH
SUNSET. FOCUS FOR ADDITIONAL CLOUD AND PRECIP DEVELOPMENT WILL
THEN FOCUS TO OUR NORTHWEST TONIGHT WITH A MID-LEVEL DISTURBANCE
MOVING INTO MINNESOTA AND NORTHERN IA. SHRA/TSRA ARE EXPECTED TO
DEVELOP ACROSS SOUTHERN MN AND MOVE SLOWLY EAST TOWARD THE IL/WI
BORDER REGION SUNDAY. AT THIS TIME IT APPEARS RFD WILL HAVE THE
BEST POTENTIAL FOR SOME SHRA BY MID-LATE MORNING. GRADUAL
WEAKENING IS EXPECTED FARTHER TO THE EAST DURING THE DAY...SO
HAVE HELD OFF FROM INTRODUCING PRECIP INTO ORD 24-30 HOUR SECTION
OF TAF WITH OVERALL LOW CONFIDENCE AT THIS TIME. HOWEVER WOULD
EXPECT THERE COULD BE SOME SHRA MAINLY NORTH/WEST OF ORD AT SOME
POINT SUNDAY AFTERNOON.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN PREVAILING WIND DIRECTION FROM THE NORTHEAST
THIS AFTERNOON.
* HIGH CONFIDENCE IN VFR CONDITIONS THROUGH SUNDAY MORNING.
* MEDIUM CONFIDENCE IN SHRA REMAINING NORTH/WEST OF ORD/MDW
THROUGH 18Z SUNDAY.
* MEDIUM-LOW CONFIDENCE IN LIGHT WIND DETAILS SUNDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE SHRA/TSRA.
MONDAY...CHANCE SHRA/TSRA. MVFR POSSIBLE.
TUESDAY THROUGH FRIDAY...DRY/VFR.
MDB
&&
.MARINE...
252 AM CDT
DEEPENING LOW PRESSURE IS MOVING EASTWARD ACROSS EASTERN QUEBEC THIS
MORNING. ONE AREA OF HIGH PRESSURE IS SPREAD ACROSS THE OHIO RIVER
VALLEY AND THE SOUTHEAST U.S. WHILE ANOTHER AREA OF HIGH PRESSURE IS
SPREAD FROM THE CANADIAN PRAIRIES TO THE CENTRAL PLAINS. THIS
NORTHERN HIGH WILL MOVE SOUTHEASTWARD AND ACROSS CENTRAL ILLINOIS
TONIGHT. A TROUGH OF LOW PRESSURE WILL THEN MOVE ACROSS THE AREA
EARLY MONDAY WITH STRONG CANADIAN HIGH PRESSURE BUILDING IN BEHIND
IT INTO TUESDAY. AS A RESULT...SOUTHERLY WINDS AHEAD OF THE FRONT
MONDAY WILL TURN NORTHERLY LATER MONDAY INTO TUESDAY AS LOW PRESSURE
BEGINS TO DEEPEN ACROSS NORTHERN NEW ENGLAND. EXPECT THAT WINDS WILL
COME UP TO AROUND 20 KT MONDAY NIGHT AND TUESDAY AS THE PRESSURE
GRADIENT TIGHTENS AND A PUSH OF COOLER AIR SPREADS IN. THIS WILL
KICK WAVES UP TO NEAR SMALL CRAFT ADVISORY CRITERIA BEFORE SUBSIDING
TUESDAY NIGHT OR WEDNESDAY MORNING. HIGH PRESSURE WILL THEN BE OVER
THE AREA WEDNESDAY THROUGH THE REST OF NEXT WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1258 PM CDT Sat Aug 10 2013
.DISCUSSION...
ISSUED 1035 AM CDT Sat Aug 10 2013
Mild weather in store for central Illinois through the weekend as
high pressure builds into the Midwest from the Plains. Warm and
sunny conditions expected with a few fair weather clouds possible
into the late morning and early afternoon hours. Going forecast
looks good. Have adjusted the high temperatures up a couple
degrees in the northern CWA to reflect a quicker warm up...as well
as a tweak to the hourly temperature forecast for the remainder of
the day. Adjustments are relatively slight and no updates to the
zone forecast are anticipated.
&&
.AVIATION...
ISSUED 1255 PM CDT Sat Aug 10 2013
Not much in the way of significant weather changes for the
aviation forecast. Light and variable winds...a few cu...and
repeat tomorrow. Overnight should be light and mostly northerly
winds with clearing for the region. The clearing is the only
question mark for the forecast with regards to potential for
fog/BR in the early morning. Not confident enough to add it to the
TAFs at this time...though guidance hints in that direction. Will
monitor this afternoons dewpoints and how much of that moisture
will mix out and erode in the boundary layer. As of now...VFR throughout.
HJS
&&
.PREV DISCUSSION...
ISSUED 240 AM CDT Sat Aug 10 2013
SHORT TERM...Today through Monday
Weak secondary cold front will continue to drop southward and
dissipate across central Illinois today, while main synoptic
boundary remains stalled from the Mid-Atlantic states W/SW into
the Southern Plains. Periods of showers and thunderstorms will
accompany the primary front, but will stay well south of the
KILX CWA. High-res HRRR hints at a few showers potentially
developing ahead of a weak short-wave across northern Indiana this
afternoon, but these would likely remain outside of central
Illinois as well. End result will be a partly to mostly sunny day
with high temperatures in the lower 80s.
High pressure will build southward into the region tonight, providing
cool/dry weather with lows dropping into the 50s. With high pressure
overhead, another pleasant summer day is in store for Sunday with
highs reaching the lower to middle 80s. Once the high begins to
slide off to the east, a light southerly return flow will allow a
warmer/more humid air mass to trickle back into the area Sunday
night into Monday. Forecast soundings indicate precipitable water
values climbing back over 1.50 inches while surface dewpoints
reach the 70-degree mark by Monday afternoon. Meanwhile...another
deep upper low will rotate southward from Hudson Bay, pushing a cold
front into Illinois. This front will interact with the increasingly
moist air mass to produce scattered showers and thunderstorms,
particularly during the afternoon and evening. Due to only modest
instability with CAPE values around 1500J/kg and best upper
support remaining further north across the Great Lakes, am not
expecting widespread convection. Will therefore maintain just
chance pops Monday into Monday night.
LONG TERM...Tuesday through Friday
Frontal boundary sags southward early next week, with model consensus
taking it south of the Ohio River by Tuesday morning. Will hold on
to just a slight chance POP across the far SE CWA into Tuesday in
case front slows. Otherwise, another cool/dry Canadian air mass
will settle southward into the region behind the departing front
for the remainder of next week. With upper flow becoming
prominently northwesterly, any potential MCS activity will likely
be shunted well W/SW of Illinois, leading to a dry forecast
through Friday. Temps next week will remain below normal, with
afternoon highs generally in the upper 70s/lower 80s and overnight
lows in the upper 50s/lower 60s.
Barnes
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1055 AM CDT SAT AUG 10 2013
.DISCUSSION...
341 AM CDT
MAIN FORECAST CONCERN IS SHRA/TSRA CHANCES SUNDAY THROUGH MONDAY
EVENING. EARLY MORNING W/V IMAGERY SHOWS BROAD TROUGHING FROM
EASTERN INTO CENTRAL CANADA AND THE NORTHERN LAKES WITH RIDGING
OVER THE WESTERN CONUS AND SEVERAL WAVES CRESTING THE RIDGE OVER
THE NORTHERN ROCKIES THAT WILL PLAY A ROLE IN OUR SENSIBLE WEATHER
ON SUNDAY AND SUNDAY NIGHT AS THEY TRAVERSE DISTURBED WEST-
NORTHWEST FLOW ALOFT. AT THE SURFACE...HIGH PRESSURE WILL CENTER
OVER THE REGION TODAY...BEFORE SLOWLY SLIDING EAST SUNDAY. A COLD
FRONT WILL MOVE THROUGH THE AREA ON MONDAY.
COOLER AIR MASS WILL FILTER INTO AREA TODAY...NOTED WITH +10 AND +11
RESPECTIVELY AT 850 MB AT KMPX AND KGRB ON THE 00Z RAOBS. THE BACK
EDGE OF CIRRUS SHIELD OVER THE AREA WILL CLEAR OFF TO THE EAST OF
BY DAYBREAK OR SO...YIELDING EARLY MORNING CLEAR SKIES...BUT
GUIDANCE SHOWS MOISTURE FROM H9-H8 SEEPING IN FROM NORTH DURING
DAY...WHICH SHOULD ALLOW FOR SCATTERED TO POSSIBLY BROKEN CUMULUS BY
THE AFTERNOON AS LOW LEVEL LAPSE RATES STEEPEN. PROGGED H8 AND H9
TEMPS SUPPORTS HIGHS IN THE UPPER 70S TO POSSIBLY AROUND 80 NORTH OF
I-80 AND LOWER 80S SOUTH...WITH A FEW MID 80S READINGS. THE
EXCEPTION WILL BE THE LAKEFRONT WITH SYNOPTIC ONSHORE FLOW AND HIGHS
ONLY IN THE LOWER AND MID 70S. ALL IN ALL...IT WILL BE A SPECTACULAR
START TO THE WEEKEND. HIGH PRESSURE OVERHEAD TONIGHT AND MAINLY
CLEAR SKIES WILL RESULT IN COOL CONDITIONS IN THE LOWER AND MID 50S
OUTSIDE OF THE CHICAGO HEAT ISLAND.
THE INITIAL LEAD WAVE CURRENTLY OVER WYOMING LOOKS TO BE APPROACHING
THE REGION BUT LIKELY FOCUS NEAR OR NORTH OF THE WISCONSIN BORDER.
BY EARLY SUNDAY...A CLUSTER OF SHRA/TSRA COULD TRAVERSE THE UPPER
MISSISSIPPI VALLEY BUT IT SHOULD WEAKEN FARTHER EAST DUE TO THE
INFLUENCE OF THE HIGH PRESSURE RIDGE...LIMITED ELEVATED INSTABILITY
AND VERY WEAK LAPSE RATES ALOFT. DESPITE SOME CONSENSUS IN THE
GUIDANCE ON TRACKING THIS FEATURE TOWARD SOUTHERN WISCONSIN...HAVE
GENERALLY MAINTAINED CHANCE POPS ALONG THE BORDER. THE EXTENT OF
CLOUD COVER WITH THIS WAVE COULD LIMIT TEMPERATURES A BIT MORE THAN
CURRENTLY DEPICTED TO THE NORTH...BUT TO THE SOUTH...WHERE LESS
CLOUD COVER IS ANTICIPATED....850/925 TEMPS WILL SUPPORT HIGHS
APPROACHING THE MID 80S. GIVEN THE FACTORS THAT WILL LIKELY LEAD TO
WEAKENING OF THE PRECIP SHIELD ASSOCIATED WITH THE MID-LEVEL
WAVE...IT STILL REMAINS POSSIBLE THAT MOST OF THE AREA COULD HAVE A
DRY SUNDAY.
STRENGTHENING LOW LEVEL FLOW WILL RESULT IN DECENT MOISTURE
TRANSPORT AND CONVERGENCE FOCUSED INTO THE NORTHERN THIRD OF CWA
SUNDAY NIGHT WITH ANOTHER MID-LEVEL FEATURE WELL AHEAD OF SURFACE
COLD FRONT THAT WILL BE APPROACHING SLOWLY FROM THE NORTHWEST. EXACT
TRACK OF MIDLEVEL WAVE AND STRENGTH OF 850-925 FLOW WILL NEED TO BE
RESOLVED...BUT HAVE BUMPED UP POPS TO HIGH CHANCE RANGE ALONG THE
WISCONSIN BORDER...TAPERING TO A DRY FORECAST IN THE FAR SOUTHERN
FORECAST SOUNDINGS SHOWING SOME ELEVATED INSTABILITY AND WARM
ADVECTION PATTERN MEANS THERE WILL LIKELY BE AT LEAST EMBEDDED
THUNDER. CLOUD COVER AND WARM ADVECTION WILL RESULT IN MILDER LOW
TEMPS.
THE CONVECTIVE EVOLUTION ON SUNDAY NIGHT INTO EARLY MONDAY WILL
DICTATE TO A LARGE EXTENT WHAT HAPPENS WITH CONVECTIVE CHANCES ON
MONDAY AHEAD OF A COLD FRONT. FAVOR A SLOWER FRONTAL PASSAGE DURING
THE AFTERNOON...BUT NOT QUITE AS SLOW AS LATEST NAM. ASSUMING CLOUD
COVER DOES NOT HINDER WARMING TOO MUCH...H85 TEMPS AROUND +15 WILL
YIELD HIGHS IN THE LOWER 80S NORTH AND MID 80S SOUTH...WITH
DEWPOINTS RETURNING TO THE MID TO UPPER 60S. THIS COULD YIELD ~1500
J/KG OF CAPE PER FORECAST SOUNDINGS...WITH DECENT CONVERGENCE FROM
THE SURFACE TO 850 MB FAVORING AT LEAST SCATTERED COVERAGE OF
THUNDERSTORMS...BUT DID NOT GO HIGHER THAN MID CHANCE POPS DUE TO
UNCERTAINTY OVER CONVECTIVE EVOLUTION. IF ENOUGH INSTABILITY
DEVELOPS...WILL NEED TO WATCH FOR A SEVERE THREAT PRIMARILY IN THE
FORM OF DAMAGING WINDS...AS NORTHWESTERLY FLOW ALOFT WILL INCREASE
TO 40 KT DURING THE DAY AND STEEP LOW LEVEL LAPSE RATES WILL DEVELOP
AS WELL. HIGH FREEZING LEVELS AND MEAGER LAPSE RATES ABOVE 600 MB
WOULD LIKELY LIMIT THE HAIL THREAT.
ANY REMAINING SHRA/TSRA SHOULD CLEAR THE SOUTHERN CWA DURING THE
EVENING...WITH HIGH PRESSURE BUILDING FROM UPPER MIDWEST BEHIND COLD
FRONT. COOL NORTHERLY FLOW FROM THE SURFACE UP TO THE MID LEVELS
THANKS TO UPPER TROUGHING OVER EASTERN CANADA WILL SET UP A BELOW
NORMAL...BUT PLEASANT TUESDAY THROUGH FRIDAY PERIOD. AFTER HIGHS
LIKELY ONLY IN THE MID 70S AWAY FROM THE LAKE TUES AND
WEDS...READINGS WILL WARM SOME BY FRIDAY AS HEIGHTS BEGIN TO RISE
AND THERMAL PROFILES SLOWLY WARM. THE LAKEFRONT WILL BE KEPT COOLER
EACH DAY BY PERSISTENT ONSHORE FLOW.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* NONE IN NEAR TERM.
RATZER
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE IS BUILDING IN FROM THE NORTHWEST THIS MORNING
FOLLOWING THE PASSAGE OF A COOL FRONTAL BOUNDARY LAST EVENING.
LIGHT NNW WINDS HAVE BEEN REPORTED AT THE TERMINALS WITH
ORD/MDW/GYY EXPECTED TO TURN MORE NORTHEASTERLY THIS MORNING
THANKS TO A COMBINATION OF THE EVOLVING PRESSURE GRADIENT AND
INFLUENCE OF LAKE MICHIGAN. SPEEDS SHOULD GENERALLY BE AT OR BELOW
10 KT THROUGH THE DAY. SCATTERED TO PERHAPS PERIODICALLY BKN VFR
CLOUDS IN THE 4000-6000 FT RANGE ARE EXPECTED TO DEVELOP LATER
THIS MORNING WITH A FEW PATCHES OF MID CLOUDS POSSIBLY WORKING IN
FROM THE NORTHWEST AS WELL...BUT THE BULK OF THIS LOOKS TO REMAIN
TO THE NORTH. WINDS WILL DROP OFF TO LIGHT AND VARIABLE OR CALM
TONIGHT WITH THE HIGH MOVING OVERHEAD. THE HIGH WILL BE IN PLACE
SUNDAY AS WELL BUT START TO SHIFT TO THE EAST LATER IN THE DAY.
THIS WILL KEEP LIGHT AND VARIABLE WINDS IN PLACE FOR MUCH OF THE
DAY BUT THERE SHOULD BE A TENDENCY FOR A PREVAILING WEST TO
SOUTHWEST WIND DIRECTION. MID CLOUD WILL LIKELY INCREASE WITH SOME
CHANCE FOR SHOWERS BUT THIS LOOKS TO PRIMARILY OCCUR NORTH OF THE
TERMINALS SO WILL CONTINUE WITH A DRY FORECAST FOR NOW.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE ALL ELEMENTS.
RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE SHRA/TSRA.
MONDAY...CHANCE SHRA/TSRA. MVFR POSSIBLE.
TUESDAY THROUGH FRIDAY...DRY/VFR.
MDB
&&
.MARINE...
252 AM CDT
DEEPENING LOW PRESSURE IS MOVING EASTWARD ACROSS EASTERN QUEBEC THIS
MORNING. ONE AREA OF HIGH PRESSURE IS SPREAD ACROSS THE OHIO RIVER
VALLEY AND THE SOUTHEAST U.S. WHILE ANOTHER AREA OF HIGH PRESSURE IS
SPREAD FROM THE CANADIAN PRAIRIES TO THE CENTRAL PLAINS. THIS
NORTHERN HIGH WILL MOVE SOUTHEASTWARD AND ACROSS CENTRAL ILLINOIS
TONIGHT. A TROUGH OF LOW PRESSURE WILL THEN MOVE ACROSS THE AREA
EARLY MONDAY WITH STRONG CANADIAN HIGH PRESSURE BUILDING IN BEHIND
IT INTO TUESDAY. AS A RESULT...SOUTHERLY WINDS AHEAD OF THE FRONT
MONDAY WILL TURN NORTHERLY LATER MONDAY INTO TUESDAY AS LOW PRESSURE
BEGINS TO DEEPEN ACROSS NORTHERN NEW ENGLAND. EXPECT THAT WINDS WILL
COME UP TO AROUND 20 KT MONDAY NIGHT AND TUESDAY AS THE PRESSURE
GRADIENT TIGHTENS AND A PUSH OF COOLER AIR SPREADS IN. THIS WILL
KICK WAVES UP TO NEAR SMALL CRAFT ADVISORY CRITERIA BEFORE SUBSIDING
TUESDAY NIGHT OR WEDNESDAY MORNING. HIGH PRESSURE WILL THEN BE OVER
THE AREA WEDNESDAY THROUGH THE REST OF NEXT WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Lincoln IL
1039 AM CDT Sat Aug 10 2013
.DISCUSSION...
ISSUED 1035 AM CDT Sat Aug 10 2013
Mild weather in store for central Illinois through the weekend as
high pressure builds into the Midwest from the Plains. Warm and
sunny conditions expected with a few fair weather clouds possible
into the late morning and early afternoon hours. Going forecast
looks good. Have adjusted the high temperatures up a couple
degrees in the northern CWA to reflect a quicker warm up...as well
as a tweak to the hourly temperature forecast for the remainder of
the day. Adjustments are relatively slight and no updates to the
zone forecast are anticipated.
HJS
&&
.AVIATION...
ISSUED 609 AM CDT Sat Aug 10 2013
VFR conditions will prevail over the next 24 hours. May see a bit
of light fog near KCMI over the next hour as skies clear, and have
seen a slow decrease in visibilities since 08Z but any MVFR
conditions will be brief. Not much in the way of cloud cover
expected now that the extensive cloudiness has largely exited the
TAF sites, with subsidence expected to keep any diurnal
development to a minimum.
Geelhart
&&
.PREV DISCUSSION...
ISSUED 240 AM CDT Sat Aug 10 2013
SHORT TERM...Today through Monday
Weak secondary cold front will continue to drop southward and
dissipate across central Illinois today, while main synoptic
boundary remains stalled from the Mid-Atlantic states W/SW into
the Southern Plains. Periods of showers and thunderstorms will
accompany the primary front, but will stay well south of the
KILX CWA. High-res HRRR hints at a few showers potentially
developing ahead of a weak short-wave across northern Indiana this
afternoon, but these would likely remain outside of central
Illinois as well. End result will be a partly to mostly sunny day
with high temperatures in the lower 80s.
High pressure will build southward into the region tonight, providing
cool/dry weather with lows dropping into the 50s. With high pressure
overhead, another pleasant summer day is in store for Sunday with
highs reaching the lower to middle 80s. Once the high begins to
slide off to the east, a light southerly return flow will allow a
warmer/more humid air mass to trickle back into the area Sunday
night into Monday. Forecast soundings indicate precipitable water
values climbing back over 1.50 inches while surface dewpoints
reach the 70-degree mark by Monday afternoon. Meanwhile...another
deep upper low will rotate southward from Hudson Bay, pushing a cold
front into Illinois. This front will interact with the increasingly
moist air mass to produce scattered showers and thunderstorms,
particularly during the afternoon and evening. Due to only modest
instability with CAPE values around 1500J/kg and best upper
support remaining further north across the Great Lakes, am not
expecting widespread convection. Will therefore maintain just
chance pops Monday into Monday night.
LONG TERM...Tuesday through Friday
Frontal boundary sags southward early next week, with model consensus
taking it south of the Ohio River by Tuesday morning. Will hold on
to just a slight chance POP across the far SE CWA into Tuesday in
case front slows. Otherwise, another cool/dry Canadian air mass
will settle southward into the region behind the departing front
for the remainder of next week. With upper flow becoming
prominently northwesterly, any potential MCS activity will likely
be shunted well W/SW of Illinois, leading to a dry forecast
through Friday. Temps next week will remain below normal, with
afternoon highs generally in the upper 70s/lower 80s and overnight
lows in the upper 50s/lower 60s.
Barnes
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
637 AM CDT SAT AUG 10 2013
.DISCUSSION...
341 AM CDT
MAIN FORECAST CONCERN IS SHRA/TSRA CHANCES SUNDAY THROUGH MONDAY
EVENING. EARLY MORNING W/V IMAGERY SHOWS BROAD TROUGHING FROM
EASTERN INTO CENTRAL CANADA AND THE NORTHERN LAKES WITH RIDGING
OVER THE WESTERN CONUS AND SEVERAL WAVES CRESTING THE RIDGE OVER
THE NORTHERN ROCKIES THAT WILL PLAY A ROLE IN OUR SENSIBLE WEATHER
ON SUNDAY AND SUNDAY NIGHT AS THEY TRAVERSE DISTURBED WEST-
NORTHWEST FLOW ALOFT. AT THE SURFACE...HIGH PRESSURE WILL CENTER
OVER THE REGION TODAY...BEFORE SLOWLY SLIDING EAST SUNDAY. A COLD
FRONT WILL MOVE THROUGH THE AREA ON MONDAY.
COOLER AIR MASS WILL FILTER INTO AREA TODAY...NOTED WITH +10 AND +11
RESPECTIVELY AT 850 MB AT KMPX AND KGRB ON THE 00Z RAOBS. THE BACK
EDGE OF CIRRUS SHIELD OVER THE AREA WILL CLEAR OFF TO THE EAST OF
BY DAYBREAK OR SO...YIELDING EARLY MORNING CLEAR SKIES...BUT
GUIDANCE SHOWS MOISTURE FROM H9-H8 SEEPING IN FROM NORTH DURING
DAY...WHICH SHOULD ALLOW FOR SCATTERED TO POSSIBLY BROKEN CUMULUS BY
THE AFTERNOON AS LOW LEVEL LAPSE RATES STEEPEN. PROGGED H8 AND H9
TEMPS SUPPORTS HIGHS IN THE UPPER 70S TO POSSIBLY AROUND 80 NORTH OF
I-80 AND LOWER 80S SOUTH...WITH A FEW MID 80S READINGS. THE
EXCEPTION WILL BE THE LAKEFRONT WITH SYNOPTIC ONSHORE FLOW AND HIGHS
ONLY IN THE LOWER AND MID 70S. ALL IN ALL...IT WILL BE A SPECTACULAR
START TO THE WEEKEND. HIGH PRESSURE OVERHEAD TONIGHT AND MAINLY
CLEAR SKIES WILL RESULT IN COOL CONDITIONS IN THE LOWER AND MID 50S
OUTSIDE OF THE CHICAGO HEAT ISLAND.
THE INITIAL LEAD WAVE CURRENTLY OVER WYOMING LOOKS TO BE APPROACHING
THE REGION BUT LIKELY FOCUS NEAR OR NORTH OF THE WISCONSIN BORDER.
BY EARLY SUNDAY...A CLUSTER OF SHRA/TSRA COULD TRAVERSE THE UPPER
MISSISSIPPI VALLEY BUT IT SHOULD WEAKEN FARTHER EAST DUE TO THE
INFLUENCE OF THE HIGH PRESSURE RIDGE...LIMITED ELEVATED INSTABILITY
AND VERY WEAK LAPSE RATES ALOFT. DESPITE SOME CONSENSUS IN THE
GUIDANCE ON TRACKING THIS FEATURE TOWARD SOUTHERN WISCONSIN...HAVE
GENERALLY MAINTAINED CHANCE POPS ALONG THE BORDER. THE EXTENT OF
CLOUD COVER WITH THIS WAVE COULD LIMIT TEMPERATURES A BIT MORE THAN
CURRENTLY DEPICTED TO THE NORTH...BUT TO THE SOUTH...WHERE LESS
CLOUD COVER IS ANTICIPATED....850/925 TEMPS WILL SUPPORT HIGHS
APPROACHING THE MID 80S. GIVEN THE FACTORS THAT WILL LIKELY LEAD TO
WEAKENING OF THE PRECIP SHIELD ASSOCIATED WITH THE MID-LEVEL
WAVE...IT STILL REMAINS POSSIBLE THAT MOST OF THE AREA COULD HAVE A
DRY SUNDAY.
STRENGTHENING LOW LEVEL FLOW WILL RESULT IN DECENT MOISTURE
TRANSPORT AND CONVERGENCE FOCUSED INTO THE NORTHERN THIRD OF CWA
SUNDAY NIGHT WITH ANOTHER MID-LEVEL FEATURE WELL AHEAD OF SURFACE
COLD FRONT THAT WILL BE APPROACHING SLOWLY FROM THE NORTHWEST. EXACT
TRACK OF MIDLEVEL WAVE AND STRENGTH OF 850-925 FLOW WILL NEED TO BE
RESOLVED...BUT HAVE BUMPED UP POPS TO HIGH CHANCE RANGE ALONG THE
WISCONSIN BORDER...TAPERING TO A DRY FORECAST IN THE FAR SOUTHERN
FORECAST SOUNDINGS SHOWING SOME ELEVATED INSTABILITY AND WARM
ADVECTION PATTERN MEANS THERE WILL LIKELY BE AT LEAST EMBEDDED
THUNDER. CLOUD COVER AND WARM ADVECTION WILL RESULT IN MILDER LOW
TEMPS.
THE CONVECTIVE EVOLUTION ON SUNDAY NIGHT INTO EARLY MONDAY WILL
DICTATE TO A LARGE EXTENT WHAT HAPPENS WITH CONVECTIVE CHANCES ON
MONDAY AHEAD OF A COLD FRONT. FAVOR A SLOWER FRONTAL PASSAGE DURING
THE AFTERNOON...BUT NOT QUITE AS SLOW AS LATEST NAM. ASSUMING CLOUD
COVER DOES NOT HINDER WARMING TOO MUCH...H85 TEMPS AROUND +15 WILL
YIELD HIGHS IN THE LOWER 80S NORTH AND MID 80S SOUTH...WITH
DEWPOINTS RETURNING TO THE MID TO UPPER 60S. THIS COULD YIELD ~1500
J/KG OF CAPE PER FORECAST SOUNDINGS...WITH DECENT CONVERGENCE FROM
THE SURFACE TO 850 MB FAVORING AT LEAST SCATTERED COVERAGE OF
THUNDERSTORMS...BUT DID NOT GO HIGHER THAN MID CHANCE POPS DUE TO
UNCERTAINTY OVER CONVECTIVE EVOLUTION. IF ENOUGH INSTABILITY
DEVELOPS...WILL NEED TO WATCH FOR A SEVERE THREAT PRIMARILY IN THE
FORM OF DAMAGING WINDS...AS NORTHWESTERLY FLOW ALOFT WILL INCREASE
TO 40 KT DURING THE DAY AND STEEP LOW LEVEL LAPSE RATES WILL DEVELOP
AS WELL. HIGH FREEZING LEVELS AND MEAGER LAPSE RATES ABOVE 600 MB
WOULD LIKELY LIMIT THE HAIL THREAT.
ANY REMAINING SHRA/TSRA SHOULD CLEAR THE SOUTHERN CWA DURING THE
EVENING...WITH HIGH PRESSURE BUILDING FROM UPPER MIDWEST BEHIND COLD
FRONT. COOL NORTHERLY FLOW FROM THE SURFACE UP TO THE MID LEVELS
THANKS TO UPPER TROUGHING OVER EASTERN CANADA WILL SET UP A BELOW
NORMAL...BUT PLEASANT TUESDAY THROUGH FRIDAY PERIOD. AFTER HIGHS
LIKELY ONLY IN THE MID 70S AWAY FROM THE LAKE TUES AND
WEDS...READINGS WILL WARM SOME BY FRIDAY AS HEIGHTS BEGIN TO RISE
AND THERMAL PROFILES SLOWLY WARM. THE LAKEFRONT WILL BE KEPT COOLER
EACH DAY BY PERSISTENT ONSHORE FLOW.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* NNW WINDS TURNING NE THIS MORNING.
MDB
//DISCUSSION...UPDATED 12Z...
HIGH PRESSURE IS BUILDING IN FROM THE NORTHWEST THIS MORNING
FOLLOWING THE PASSAGE OF A COOL FRONTAL BOUNDARY LAST EVENING.
LIGHT NNW WINDS HAVE BEEN REPORTED AT THE TERMINALS WITH
ORD/MDW/GYY EXPECTED TO TURN MORE NORTHEASTERLY THIS MORNING
THANKS TO A COMBINATION OF THE EVOLVING PRESSURE GRADIENT AND
INFLUENCE OF LAKE MICHIGAN. SPEEDS SHOULD GENERALLY BE AT OR BELOW
10 KT THROUGH THE DAY. SCATTERED TO PERHAPS PERIODICALLY BKN VFR
CLOUDS IN THE 4000-6000 FT RANGE ARE EXPECTED TO DEVELOP LATER
THIS MORNING WITH A FEW PATCHES OF MID CLOUDS POSSIBLY WORKING IN
FROM THE NORTHWEST AS WELL...BUT THE BULK OF THIS LOOKS TO REMAIN
TO THE NORTH. WINDS WILL DROP OFF TO LIGHT AND VARIABLE OR CALM
TONIGHT WITH THE HIGH MOVING OVERHEAD. THE HIGH WILL BE IN PLACE
SUNDAY AS WELL BUT START TO SHIFT TO THE EAST LATER IN THE DAY.
THIS WILL KEEP LIGHT AND VARIABLE WINDS IN PLACE FOR MUCH OF THE
DAY BUT THERE SHOULD BE A TENDENCY FOR A PREVAILING WEST TO
SOUTHWEST WIND DIRECTION. MID CLOUD WILL LIKELY INCREASE WITH SOME
CHANCE FOR SHOWERS BUT THIS LOOKS TO PRIMARILY OCCUR NORTH OF THE
TERMINALS SO WILL CONTINUE WITH A DRY FORECAST FOR NOW.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN WINDS TURNING NE...MEDIUM-HIGH CONFIDENCE IN
TIMING.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT...CHANCE SHRA/TSRA.
MONDAY...CHANCE SHRA/TSRA. MVFR POSSIBLE.
TUESDAY THROUGH FRIDAY...DRY/VFR.
MDB
&&
.MARINE...
252 AM CDT
DEEPENING LOW PRESSURE IS MOVING EASTWARD ACROSS EASTERN QUEBEC THIS
MORNING. ONE AREA OF HIGH PRESSURE IS SPREAD ACROSS THE OHIO RIVER
VALLEY AND THE SOUTHEAST U.S. WHILE ANOTHER AREA OF HIGH PRESSURE IS
SPREAD FROM THE CANADIAN PRAIRIES TO THE CENTRAL PLAINS. THIS
NORTHERN HIGH WILL MOVE SOUTHEASTWARD AND ACROSS CENTRAL ILLINOIS
TONIGHT. A TROUGH OF LOW PRESSURE WILL THEN MOVE ACROSS THE AREA
EARLY MONDAY WITH STRONG CANADIAN HIGH PRESSURE BUILDING IN BEHIND
IT INTO TUESDAY. AS A RESULT...SOUTHERLY WINDS AHEAD OF THE FRONT
MONDAY WILL TURN NORTHERLY LATER MONDAY INTO TUESDAY AS LOW PRESSURE
BEGINS TO DEEPEN ACROSS NORTHERN NEW ENGLAND. EXPECT THAT WINDS WILL
COME UP TO AROUND 20 KT MONDAY NIGHT AND TUESDAY AS THE PRESSURE
GRADIENT TIGHTENS AND A PUSH OF COOLER AIR SPREADS IN. THIS WILL
KICK WAVES UP TO NEAR SMALL CRAFT ADVISORY CRITERIA BEFORE SUBSIDING
TUESDAY NIGHT OR WEDNESDAY MORNING. HIGH PRESSURE WILL THEN BE OVER
THE AREA WEDNESDAY THROUGH THE REST OF NEXT WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
National Weather Service Lincoln IL
610 AM CDT Sat Aug 10 2013
.DISCUSSION...
ISSUED 240 AM CDT Sat Aug 10 2013
SHORT TERM...Today through Monday
Weak secondary cold front will continue to drop southward and
dissipate across central Illinois today, while main synoptic
boundary remains stalled from the Mid-Atlantic states W/SW into
the Southern Plains. Periods of showers and thunderstorms will
accompany the primary front, but will stay well south of the
KILX CWA. High-res HRRR hints at a few showers potentially
developing ahead of a weak short-wave across northern Indiana this
afternoon, but these would likely remain outside of central
Illinois as well. End result will be a partly to mostly sunny day
with high temperatures in the lower 80s.
High pressure will build southward into the region tonight, providing
cool/dry weather with lows dropping into the 50s. With high pressure
overhead, another pleasant summer day is in store for Sunday with
highs reaching the lower to middle 80s. Once the high begins to
slide off to the east, a light southerly return flow will allow a
warmer/more humid air mass to trickle back into the area Sunday
night into Monday. Forecast soundings indicate precipitable water
values climbing back over 1.50 inches while surface dewpoints
reach the 70-degree mark by Monday afternoon. Meanwhile...another
deep upper low will rotate southward from Hudson Bay, pushing a cold
front into Illinois. This front will interact with the increasingly
moist air mass to produce scattered showers and thunderstorms,
particularly during the afternoon and evening. Due to only modest
instability with CAPE values around 1500J/kg and best upper
support remaining further north across the Great Lakes, am not
expecting widespread convection. Will therefore maintain just
chance pops Monday into Monday night.
LONG TERM...Tuesday through Friday
Frontal boundary sags southward early next week, with model consensus
taking it south of the Ohio River by Tuesday morning. Will hold on
to just a slight chance POP across the far SE CWA into Tuesday in
case front slows. Otherwise, another cool/dry Canadian air mass
will settle southward into the region behind the departing front
for the remainder of next week. With upper flow becoming
prominently northwesterly, any potential MCS activity will likely
be shunted well W/SW of Illinois, leading to a dry forecast
through Friday. Temps next week will remain below normal, with
afternoon highs generally in the upper 70s/lower 80s and overnight
lows in the upper 50s/lower 60s.
Barnes
&&
.AVIATION...
ISSUED 609 AM CDT Sat Aug 10 2013
VFR conditions will prevail over the next 24 hours. May see a bit
of light fog near KCMI over the next hour as skies clear, and have
seen a slow decrease in visibilities since 08Z but any MVFR
conditions will be brief. Not much in the way of cloud cover
expected now that the extensive cloudiness has largely exited the
TAF sites, with subsidence expected to keep any diurnal
development to a minimum.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
254 AM CDT SAT AUG 10 2013
.DISCUSSION...
249 PM CDT
SYNOPSIS...A COLD FRONT PASSES THROUGH THE REGION TONIGHT WHILE AN
UPPER LEVEL LOW SHIFTS EAST INTO QUEBEC TONIGHT. COOL CONDITIONS
CONTINUE WITH A CHANCE OF RAIN EARLY NEXT WEEK.
REST OF TODAY THROUGH SATURDAY...
A COLD FRONT EXTENDS FROM GAYLORD MI THROUGH DUBUQUE IOWA AND IT
WILL SLOWLY PASS THROUGH THE REGION TONIGHT. ISOLATED SHOWERS WILL
DEVELOP ALONG THE FRONT THIS AFTERNOON...WITH A FEW ALREADY FORMING
WEST OF THE CWA IN FAR NW IL AND IA. KEPT THUNDER OUT OF THE
FORECAST THIS AFTERNOON AS CAPE IS 800 J/KG OR LESS ACROSS THE
REGION ACCORDING TO THE LATEST LAPS ANALYSIS. AS SUCH MAY SEE A
LIGHTNING STRIKE OR TWO BUT OVERALL JUST EXPECTING SPOTTY SHOWERS
THIS AFTERNOON AND EVENING. CLOUDS WILL THIN ALLOWING MIN TEMPS TO
FALL INTO THE UPPER 50S TO LOW 60S TONIGHT.
RELATIVELY ZONAL FLOW SETS UP ALOFT TOMORROW WHILE THE UPPER LEVEL
RIDGE BUILDS OVER THE WESTERN U.S. SURFACE HIGH PRESSURE ARRIVES
FROM THE NORTHWEST RESULTING IN SCATTERED CLOUD COVER AND TEMPS
AROUND 80. A LAKE BREEZE WILL KEEP HIGH TEMPS DOWNTOWN IN THE MID
70S.
SUNDAY THROUGH MONDAY NIGHT...
A SHORTWAVE PASSES OVER WISCONSIN LATE SATURDAY NIGHT INTO SUNDAY
MORNING PRODUCING AN AREA OF SHOWERS. PUT A SLIGHT CHANCE OF SHRA
ACROSS THE IL/WI STATE LINE DURING THE DAY ON SUNDAY BUT EXPECTING
THE MAJORITY OF PRECIP TO REMAIN CLOSER TO THE IMPULSE IN WI. MAY
ALSO SEE A FEW THUNDERSTORMS AS GUIDANCE SUGGESTS WE MAY HAVE AROUND
1500 J/KG OVER FAR NORTHERN IL SUNDAY AFTERNOON. BUT ONCE
AGAIN...THE BETTER FORCING WILL BE CLOSER TO THE SHORTWAVE IN WI SO
THINKING THE MORE WIDESPREAD THUNDERSTORM ACTIVITY WILL BE TO OUR
NORTH. PWAT VALUES WILL BE BTWN 1 AND 1.5 INCHES SO MODERATE TO
ISOLATED HEAVY SHOWERS ARE POSSIBLE.
AN UPPER LEVEL LOW ROTATES OVER HUDSON BAY AND NORTHERN ONTARIO
SUNDAY EVENING AND NIGHT...AND THE TROUGH AXIS PUSHES THROUGH THE
REGION MONDAY. AS THE TROUGH AXIS APPROACHES...SHOWERS AND
THUNDERSTORMS PUSH SOUTH THROUGH THE CWA WITH THE BEST FOCUS OF
PRECIP ALONG AND NORTH OF I-80 BY MONDAY MORNING.
HOWEVER...EXPECTING A CHANCE FOR PRECIP ACROSS THE ENTIRE CWA DURING
THE DAY ON MONDAY. 1-2 INCHES OF PWAT IS EXPECTED SO HOPEFULLY WE
WILL SEE THE SOAKING RAIN THAT IS NEEDED IN MANY PARTS OF THE CWA.
RAIN SHIFTS TO THE SOUTHEAST AHEAD OF THE TROUGH AXIS MONDAY NIGHT.
TEMPS REMAIN BELOW NORMAL WITH HIGHS AROUND 80...EXPECT COOLER BY
THE LAKE...AND LOWS IN THE LOW 60S.
EXTENDED...TUESDAY THROUGH NEXT THURSDAY...
THE UPPER LEVEL TROUGH SHIFTS EAST INTO QUEBEC USHERING IN ANOTHER
PUSH OF COOL AIR. NORTHWEST FLOW IS OVER THE AREA THROUGH THE END
OF NEXT WEEK AND A SURFACE HIGH MOVES OVER THE REGION TUESDAY
AFTERNOON. THE HIGH STAYS WITH US THROUGH THE REST OF NEXT WEEK
WITH DRY AND COOL CONDITIONS EXPECTED.
JEE
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* NORTH-NORTHWEST WINDS TURNING NORTHEAST SOMETIME THIS MORNING.
MDB
//DISCUSSION...UPDATED 06Z...
A WEAK COOL FRONT CONTINUES TO SLOWLY MOVE SOUTHEAST ACROSS THE
TERMINALS EARLY TONIGHT. WINDS BEHIND THE FRONT ARE TURNING
NORTHWESTERLY...BUT THIS IS TAKING SOME TIME TO OCCUR WITH
MDW/DPA/GYY HOLDING WNW. EXPECT THESE SITES TO TURN NNW WITH TIME
OVERNIGHT WITH SPEEDS AROUND 6 KT OR LESS. LOWER LEVEL VFR CLOUDS
WILL STEADILY MOVE OUT OF THE AREA WITH A FAIRLY DENSE CIRRUS
SHIELD LINGERING THROUGH THE NIGHT BEFORE DEPARTING TOWARD
DAYBREAK. LATEST OBSERVED TRENDS AND GUIDANCE SUPPORTS A SHIFT TO
NORTHEAST WINDS AT ORD/MDW DURING THE MID/LATE MORNING HOURS SO
HAVE ADJUSTED TIMING FOR THIS IN THE TAFS. WINDS LOOK TO BECOME
LIGHT AND VARIABLE OR CALM THIS EVENING AS HIGH PRESSURE MOVES
RIGHT OVERHEAD.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE IN WINDS TURNING NORTHEAST WITH MEDIUM
CONFIDENCE IN TIMING.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
* SUNDAY...CHANCE OF TSRA TOWARD EVENING.
* MONDAY...CHANCE OF TSRA. MVFR POSSIBLE. LAKE BREEZE/WIND SHIFT.
* TUESDAY THROUGH THURSDAY...DRY/VFR.
&&
.MARINE...
252 AM CDT
DEEPENING LOW PRESSURE IS MOVING EASTWARD ACROSS EASTERN QUEBEC THIS
MORNING. ONE AREA OF HIGH PRESSURE IS SPREAD ACROSS THE OHIO RIVER
VALLEY AND THE SOUTHEAST U.S. WHILE ANOTHER AREA OF HIGH PRESSURE IS
SPREAD FROM THE CANADIAN PRAIRIES TO THE CENTRAL PLAINS. THIS
NORTHERN HIGH WILL MOVE SOUTHEASTWARD AND ACROSS CENTRAL ILLINOIS
TONIGHT. A TROUGH OF LOW PRESSURE WILL THEN MOVE ACROSS THE AREA
EARLY MONDAY WITH STRONG CANADIAN HIGH PRESSURE BUILDING IN BEHIND
IT INTO TUESDAY. AS A RESULT...SOUTHERLY WINDS AHEAD OF THE FRONT
MONDAY WILL TURN NORTHERLY LATER MONDAY INTO TUESDAY AS LOW PRESSURE
BEGINS TO DEEPEN ACROSS NORTHERN NEW ENGLAND. EXPECT THAT WINDS WILL
COME UP TO AROUND 20 KT MONDAY NIGHT AND TUESDAY AS THE PRESSURE
GRADIENT TIGHTENS AND A PUSH OF COOLER AIR SPREADS IN. THIS WILL
KICK WAVES UP TO NEAR SMALL CRAFT ADVISORY CRITERIA BEFORE SUBSIDING
TUESDAY NIGHT OR WEDNESDAY MORNING. HIGH PRESSURE WILL THEN BE OVER
THE AREA WEDNESDAY THROUGH THE REST OF NEXT WEEK.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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Area Forecast Discussion
National Weather Service Lincoln IL
240 AM CDT Sat Aug 10 2013
.DISCUSSION...
ISSUED 240 AM CDT Sat Aug 10 2013
SHORT TERM...Today through Monday
Weak secondary cold front will continue to drop southward and
dissipate across central Illinois today, while main synoptic
boundary remains stalled from the Mid-Atlantic states W/SW into
the Southern Plains. Periods of showers and thunderstorms will
accompany the primary front, but will stay well south of the
KILX CWA. High-res HRRR hints at a few showers potentially
developing ahead of a weak short-wave across northern Indiana this
afternoon, but these would likely remain outside of central
Illinois as well. End result will be a partly to mostly sunny day
with high temperatures in the lower 80s.
High pressure will build southward into the region tonight, providing
cool/dry weather with lows dropping into the 50s. With high pressure
overhead, another pleasant summer day is in store for Sunday with
highs reaching the lower to middle 80s. Once the high begins to
slide off to the east, a light southerly return flow will allow a
warmer/more humid airmass to trickle back into the area Sunday
night into Monday. Forecast soundings indicate precipitable water
values climbing back over 1.50 inches while surface dewpoints
reach the 70-degree mark by Monday afternoon. Meanwhile...another
deep upper low will rotate southward from Hudson Bay, pushing a cold
front into Illinois. This front will interact with the increasingly
moist airmass to produce scattered showers and thunderstorms,
particularly during the afternoon and evening. Due to only modest
instability with CAPE values around 1500J/kg and best upper
support remaining further north across the Great Lakes, am not
expecting widespread convection. Will therefore maintain just
chance pops Monday into Monday night.
LONG TERM...Tuesday through Friday
Frontal boundary sags southward early next week, with model consensus
taking it south of the Ohio River by Tuesday morning. Will hold on
to just a slight chance POP across the far SE CWA into Tuesday in
case front slows. Otherwise, another cool/dry Canadian airmass
will settle southward into the region behind the departing front
for the remainder of next week. With upper flow becoming
prominently northwesterly, any potential MCS activity will likely
be shunted well W/SW of Illinois, leading to a dry forecast
through Friday. Temps next week will remain below normal, with
afternoon highs generally in the upper 70s/lower 80s and overnight
lows in the upper 50s/lower 60s.
BARNES
&&
.AVIATION...
ISSUED 1150 PM CDT Fri Aug 9 2013
Generally quiet/VFR aviation weather conditions expected across the
central Illinois terminals through the 06Z TAF valid time,
although there may be patchy MVFR fog overnight tonight. A weak
frontal boundary will settle south of the area tonight, allowing
high pressure to build into the area for Saturday. The majority of
the cloud cover will be of the mid/high level variety, but
scattered VFR level CU should develop with diurnal heating
Saturday.
BAK
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
210 PM EDT SAT AUG 10 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 339 AM EDT SAT AUG 10 2013
A SECONDARY COLD FRONT WILL TRAVERSE CENTRAL INDIANA
TODAY...BRINGING A SLIGHT CHANCE FOR SOME SCATTERED SHOWERS
THIS MORNING AND ISOLATED THUNDERSTORMS THIS AFTERNOON. HIGH
PRESSURE WILL RESULT IN DRY CONDITIONS FROM TONIGHT THROUGH
SUNDAY. HOWEVER...A WEAK SURFACE LOW WILL TRY TO ENTER CENTRAL
INDIANA FROM THE SOUTH ON MONDAY...FOLLOWED BY A STRONGER COLD
FRONT THAT NIGHT WHICH WILL BRING ADDITIONAL SHOWER AND
THUNDERSTORM CHANCES INTO TUESDAY MORNING.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 955 AM EDT SAT AUG 10 2013
MID AND HIGH LEVEL CLOUDS PERSISTING SO FAR THIS MORNING ACROSS
ALL BUT NORTHERN PORTIONS OF THE FORECAST AREA. A FEW LIGHT
SHOWERS CONTINUE TO GRAZE FAR SOUTHERN COUNTIES AS A WEAK WAVE
ALOFT PASSES THROUGH THE LOWER OHIO VALLEY. TEMPS WERE GENERALLY
IN THE LOWER AND MIDDLE 70S AS OF 13Z.
FORECAST IN GOOD SHAPE THIS MORNING WITH JUST MINOR CHANGES
NEEDED. WEAK SURFACE WAVE ALONG SECONDARY FRONT NOTED ACROSS
NORTHEAST INDIANA WITH THE BOUNDARY EXTENDING SOUTHWEST INTO
CENTRAL ILLINOIS. THE BOUNDARY WILL PROGRESS SLOWLY SOUTH ACROSS
THE FORECAST AREA THROUGH THE AFTERNOON AND EVENING. WHILE FORCING
ALOFT REMAINS VERY WEAK...PRESENCE OF LOW LEVEL MOISTURE AND WEAK
INSTABILITY AHEAD OF THE BOUNDARY WILL LIKELY BE ENOUGH TO
GENERATE ISOLATED CONVECTION THROUGH THE AFTERNOON AND EARLY
EVENING...ESPECIALLY OVER THE SOUTHEAST HALF OF THE FORECAST AREA.
CURRENT HRRR CAPTURES THIS IDEA WELL...HINTING AT BEST POTENTIAL
FOR CONVECTIVE DEVELOPMENT OVER EASTERN COUNTIES WHICH MAKES SENSE
WITH SLIGHTLY BETTER FORCING ALOFT TO THE EAST OVER OHIO. WILL
MAINTAIN LOW CHANCE POPS THROUGH THE AFTERNOON OVER ALL BUT THE
NORTHERN WABASH VALLEY...AND INTO THE EVENING OVER FAR SOUTHERN
COUNTIES.
BUMPED UP HIGHS IN NORTHERN COUNTIES BY A DEGREE OR TWO...
ESPECIALLY WITH A MAINLY SUNNY START BEFORE CU FIELD DEVELOPS
LATER TODAY. OTHERWISE FORECAST HIGH TEMPS LOOK REASONABLE.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
HIGH PRESSURE WILL BUILD INTO CENTRAL INDIANA TONIGHT...INFLUENCING
THE AREA THROUGH SUNDAY NIGHT. THE NEXT CHANCE FOR ANY MEASURABLE
PRECIP WILL BE MONDAY/MONDAY NIGHT AS A COLD FRONT ENTERS FROM THE
NORTHWEST. THIS FRONT WILL COMBINE WITH SOME MOISTURE RETROGRADING
BACK INTO THE REGION. AS A RESULT...CHANCE POPS SEEM REASONABLE AT
THIS TIME DURING THE MONDAY/MONDAY NIGHT TIME FRAME.
TEMPS...MODELS ARE SHOWING SOME INCONSISTENCY WITH REGARD TO
CHANGING WEATHER PATTERN AT END OF SHORT TERM PERIOD. WENT WITH A
BLEND FROM TONIGHT THROUGH SUNDAY NIGHT...AND THEN LEANED TOWARD
THE WARMER GFS ON MONDAY TO CAPTURE ANY WARM AIR ADVECTION WITH A
SURFACE WARM FRONT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
ISSUED AT 210 PM EDT SAT AUG 10 2013
MODELS CONTINUE TO BE CLOSE ENOUGH THAT THE ALLBLEND INITIALIZATION
CAN BE USED WITH LITTLE CHANGE.
CENTRAL INDIANA WILL REMAIN UNDER AN UPPER TROUGH THROUGH THE
PERIOD. COOL CANADIAN HIGH PRESSURE AT THE SURFACE WILL PROVIDE DRY
CONDITIONS WITH BELOW AVERAGE TEMPERATURES THROUGH THE PERIOD.
&&
.AVIATION /DISCUSSION FOR THE 101800Z TAFS/...
ISSUED AT 1253 PM EDT SAT AUG 10 2013
GENERALLY VFR CONDITIONS THROUGH THIS EVENING...THEN IFR FOG
DEVELOPING AT MOST SITES OVERNIGHT. VFR RETURNS SUNDAY MID-MORNING.
CU WILL CONTINUE TO DEVELOP...AND CEILINGS FROM THE CU MAY OCCUR AT
TIMES AT THE SITES.
CU WILL DISSIPATE AFTER SUNSET LEAVING CLEAR SKIES. WITH LIGHT WINDS
AND LINGERING LOW LEVEL MOISTURE...EXPECT FOG TO DEVELOP. WILL
CONTINUE WITH IFR FORECAST FOR ALL BUT KIND. FOG WILL BURN OFF
SUNDAY MORNING.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....50
AVIATION...50
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1253 PM EDT SAT AUG 10 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 339 AM EDT SAT AUG 10 2013
A SECONDARY COLD FRONT WILL TRAVERSE CENTRAL INDIANA
TODAY...BRINGING A SLIGHT CHANCE FOR SOME SCATTERED SHOWERS
THIS MORNING AND ISOLATED THUNDERSTORMS THIS AFTERNOON. HIGH
PRESSURE WILL RESULT IN DRY CONDITIONS FROM TONIGHT THROUGH
SUNDAY. HOWEVER...A WEAK SURFACE LOW WILL TRY TO ENTER CENTRAL
INDIANA FROM THE SOUTH ON MONDAY...FOLLOWED BY A STRONGER COLD
FRONT THAT NIGHT WHICH WILL BRING ADDITIONAL SHOWER AND
THUNDERSTORM CHANCES INTO TUESDAY MORNING.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 955 AM EDT SAT AUG 10 2013
MID AND HIGH LEVEL CLOUDS PERSISTING SO FAR THIS MORNING ACROSS
ALL BUT NORTHERN PORTIONS OF THE FORECAST AREA. A FEW LIGHT
SHOWERS CONTINUE TO GRAZE FAR SOUTHERN COUNTIES AS A WEAK WAVE
ALOFT PASSES THROUGH THE LOWER OHIO VALLEY. TEMPS WERE GENERALLY
IN THE LOWER AND MIDDLE 70S AS OF 13Z.
FORECAST IN GOOD SHAPE THIS MORNING WITH JUST MINOR CHANGES
NEEDED. WEAK SURFACE WAVE ALONG SECONDARY FRONT NOTED ACROSS
NORTHEAST INDIANA WITH THE BOUNDARY EXTENDING SOUTHWEST INTO
CENTRAL ILLINOIS. THE BOUNDARY WILL PROGRESS SLOWLY SOUTH ACROSS
THE FORECAST AREA THROUGH THE AFTERNOON AND EVENING. WHILE FORCING
ALOFT REMAINS VERY WEAK...PRESENCE OF LOW LEVEL MOISTURE AND WEAK
INSTABILITY AHEAD OF THE BOUNDARY WILL LIKELY BE ENOUGH TO
GENERATE ISOLATED CONVECTION THROUGH THE AFTERNOON AND EARLY
EVENING...ESPECIALLY OVER THE SOUTHEAST HALF OF THE FORECAST AREA.
CURRENT HRRR CAPTURES THIS IDEA WELL...HINTING AT BEST POTENTIAL
FOR CONVECTIVE DEVELOPMENT OVER EASTERN COUNTIES WHICH MAKES SENSE
WITH SLIGHTLY BETTER FORCING ALOFT TO THE EAST OVER OHIO. WILL
MAINTAIN LOW CHANCE POPS THROUGH THE AFTERNOON OVER ALL BUT THE
NORTHERN WABASH VALLEY...AND INTO THE EVENING OVER FAR SOUTHERN
COUNTIES.
BUMPED UP HIGHS IN NORTHERN COUNTIES BY A DEGREE OR TWO...
ESPECIALLY WITH A MAINLY SUNNY START BEFORE CU FIELD DEVELOPS
LATER TODAY. OTHERWISE FORECAST HIGH TEMPS LOOK REASONABLE.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
HIGH PRESSURE WILL BUILD INTO CENTRAL INDIANA TONIGHT...INFLUENCING
THE AREA THROUGH SUNDAY NIGHT. THE NEXT CHANCE FOR ANY MEASURABLE
PRECIP WILL BE MONDAY/MONDAY NIGHT AS A COLD FRONT ENTERS FROM THE
NORTHWEST. THIS FRONT WILL COMBINE WITH SOME MOISTURE RETROGRADING
BACK INTO THE REGION. AS A RESULT...CHANCE POPS SEEM REASONABLE AT
THIS TIME DURING THE MONDAY/MONDAY NIGHT TIME FRAME.
TEMPS...MODELS ARE SHOWING SOME INCONSISTENCY WITH REGARD TO
CHANGING WEATHER PATTERN AT END OF SHORT TERM PERIOD. WENT WITH A
BLEND FROM TONIGHT THROUGH SUNDAY NIGHT...AND THEN LEANED TOWARD
THE WARMER GFS ON MONDAY TO CAPTURE ANY WARM AIR ADVECTION WITH A
SURFACE WARM FRONT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
ENSEMBLES INDICATE A RATHER STABLE WEATHER PATTERN DURING THIS
PERIOD. SUBTROPICAL RIDGE REMAINS ALONG THE GULF COAST/SOUTHERN
PLAINS REGION...WHILE UPPER TROUGHING CONTINUES OVER THE GREAT LAKES
AND NEW ENGLAND.
ENSEMBLES SUGGEST AN UPPER DISTURBANCE WILL BE IN THE PROCESS OF
PASSING OVER THE GREAT LAKES ON TUESDAY. WILL KEEP SOME CHANCE POPS
IN THE FORECAST ON TUESDAY TO COVER THIS FEATURE.
OTHERWISE...ENSEMBLES INDICATING LITTLE THREAT FOR PRECIPITATION FOR
THE REST OF THE EXTENDED...SO WILL GO DRY AFTER TUESDAY.
&&
.AVIATION /DISCUSSION FOR THE 101800Z TAFS/...
ISSUED AT 1253 PM EDT SAT AUG 10 2013
GENERALLY VFR CONDITIONS THROUGH THIS EVENING...THEN IFR FOG
DEVELOPING AT MOST SITES OVERNIGHT. VFR RETURNS SUNDAY MID-MORNING.
CU WILL CONTINUE TO DEVELOP...AND CEILINGS FROM THE CU MAY OCCUR AT
TIMES AT THE SITES.
CU WILL DISSIPATE AFTER SUNSET LEAVING CLEAR SKIES. WITH LIGHT WINDS
AND LINGERING LOW LEVEL MOISTURE...EXPECT FOG TO DEVELOP. WILL
CONTINUE WITH IFR FORECAST FOR ALL BUT KIND. FOG WILL BURN OFF
SUNDAY MORNING.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....JAS
AVIATION...50
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1022 AM EDT SAT AUG 10 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 339 AM EDT SAT AUG 10 2013
A SECONDARY COLD FRONT WILL TRAVERSE CENTRAL INDIANA
TODAY...BRINGING A SLIGHT CHANCE FOR SOME SCATTERED SHOWERS
THIS MORNING AND ISOLATED THUNDERSTORMS THIS AFTERNOON. HIGH
PRESSURE WILL RESULT IN DRY CONDITIONS FROM TONIGHT THROUGH
SUNDAY. HOWEVER...A WEAK SURFACE LOW WILL TRY TO ENTER CENTRAL
INDIANA FROM THE SOUTH ON MONDAY...FOLLOWED BY A STRONGER COLD
FRONT THAT NIGHT WHICH WILL BRING ADDITIONAL SHOWER AND
THUNDERSTORM CHANCES INTO TUESDAY MORNING.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 955 AM EDT SAT AUG 10 2013
MID AND HIGH LEVEL CLOUDS PERSISTING SO FAR THIS MORNING ACROSS
ALL BUT NORTHERN PORTIONS OF THE FORECAST AREA. A FEW LIGHT
SHOWERS CONTINUE TO GRAZE FAR SOUTHERN COUNTIES AS A WEAK WAVE
ALOFT PASSES THROUGH THE LOWER OHIO VALLEY. TEMPS WERE GENERALLY
IN THE LOWER AND MIDDLE 70S AS OF 13Z.
FORECAST IN GOOD SHAPE THIS MORNING WITH JUST MINOR CHANGES
NEEDED. WEAK SURFACE WAVE ALONG SECONDARY FRONT NOTED ACROSS
NORTHEAST INDIANA WITH THE BOUNDARY EXTENDING SOUTHWEST INTO
CENTRAL ILLINOIS. THE BOUNDARY WILL PROGRESS SLOWLY SOUTH ACROSS
THE FORECAST AREA THROUGH THE AFTERNOON AND EVENING. WHILE FORCING
ALOFT REMAINS VERY WEAK...PRESENCE OF LOW LEVEL MOISTURE AND WEAK
INSTABILITY AHEAD OF THE BOUNDARY WILL LIKELY BE ENOUGH TO
GENERATE ISOLATED CONVECTION THROUGH THE AFTERNOON AND EARLY
EVENING...ESPECIALLY OVER THE SOUTHEAST HALF OF THE FORECAST AREA.
CURRENT HRRR CAPTURES THIS IDEA WELL...HINTING AT BEST POTENTIAL
FOR CONVECTIVE DEVELOPMENT OVER EASTERN COUNTIES WHICH MAKES SENSE
WITH SLIGHTLY BETTER FORCING ALOFT TO THE EAST OVER OHIO. WILL
MAINTAIN LOW CHANCE POPS THROUGH THE AFTERNOON OVER ALL BUT THE
NORTHERN WABASH VALLEY...AND INTO THE EVENING OVER FAR SOUTHERN
COUNTIES.
BUMPED UP HIGHS IN NORTHERN COUNTIES BY A DEGREE OR TWO...
ESPECIALLY WITH A MAINLY SUNNY START BEFORE CU FIELD DEVELOPS
LATER TODAY. OTHERWISE FORECAST HIGH TEMPS LOOK REASONABLE.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
HIGH PRESSURE WILL BUILD INTO CENTRAL INDIANA TONIGHT...INFLUENCING
THE AREA THROUGH SUNDAY NIGHT. THE NEXT CHANCE FOR ANY MEASURABLE
PRECIP WILL BE MONDAY/MONDAY NIGHT AS A COLD FRONT ENTERS FROM THE
NORTHWEST. THIS FRONT WILL COMBINE WITH SOME MOISTURE RETROGRADING
BACK INTO THE REGION. AS A RESULT...CHANCE POPS SEEM REASONABLE AT
THIS TIME DURING THE MONDAY/MONDAY NIGHT TIME FRAME.
TEMPS...MODELS ARE SHOWING SOME INCONSISTENCY WITH REGARD TO
CHANGING WEATHER PATTERN AT END OF SHORT TERM PERIOD. WENT WITH A
BLEND FROM TONIGHT THROUGH SUNDAY NIGHT...AND THEN LEANED TOWARD
THE WARMER GFS ON MONDAY TO CAPTURE ANY WARM AIR ADVECTION WITH A
SURFACE WARM FRONT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
ENSEMBLES INDICATE A RATHER STABLE WEATHER PATTERN DURING THIS
PERIOD. SUBTROPICAL RIDGE REMAINS ALONG THE GULF COAST/SOUTHERN
PLAINS REGION...WHILE UPPER TROUGHING CONTINUES OVER THE GREAT LAKES
AND NEW ENGLAND.
ENSEMBLES SUGGEST AN UPPER DISTURBANCE WILL BE IN THE PROCESS OF
PASSING OVER THE GREAT LAKES ON TUESDAY. WILL KEEP SOME CHANCE POPS
IN THE FORECAST ON TUESDAY TO COVER THIS FEATURE.
OTHERWISE...ENSEMBLES INDICATING LITTLE THREAT FOR PRECIPITATION FOR
THE REST OF THE EXTENDED...SO WILL GO DRY AFTER TUESDAY.
&&
.AVIATION /DISCUSSION FOR THE 101500Z TAF UPDATE/...
ISSUED AT 1022 AM EDT SAT AUG 10 2013
BACK EDGE OF AC DECK IS ALMOST TO KIND. AFTER THAT MOVES THROUGH
EXPECT SCATTERED CU AND AC.
PREVIOUS DISCUSSION FOLLOWS...
SOME SPRINKLES POSSIBLE IN THE VICINITY OF THE TAF SITES THROUGH
ABOUT MID MORNING...OTHERWISE CONVECTIVE PARAMETERS SUGGEST ANY DEEP
CONVECTION WILL BE SOUTH OF THE TAF SITES TODAY.
SOME DIURNAL CLOUDS BASED AROUND 030 EXPECTED TO DEVELOP TOWARDS THE
MIDDAY HOURS.
NO VISIBILITY OR WIND ISSUES EXPECTED AT THE TAF SITES THROUGH
110000Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....JAS
AVIATION...JAS/50
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
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WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
955 AM EDT SAT AUG 10 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 339 AM EDT SAT AUG 10 2013
A SECONDARY COLD FRONT WILL TRAVERSE CENTRAL INDIANA
TODAY...BRINGING A SLIGHT CHANCE FOR SOME SCATTERED SHOWERS
THIS MORNING AND ISOLATED THUNDERSTORMS THIS AFTERNOON. HIGH
PRESSURE WILL RESULT IN DRY CONDITIONS FROM TONIGHT THROUGH
SUNDAY. HOWEVER...A WEAK SURFACE LOW WILL TRY TO ENTER CENTRAL
INDIANA FROM THE SOUTH ON MONDAY...FOLLOWED BY A STRONGER COLD
FRONT THAT NIGHT WHICH WILL BRING ADDITIONAL SHOWER AND
THUNDERSTORM CHANCES INTO TUESDAY MORNING.
&&
.NEAR TERM /REST OF TODAY/...
ISSUED AT 955 AM EDT SAT AUG 10 2013
MID AND HIGH LEVEL CLOUDS PERSISTING SO FAR THIS MORNING ACROSS
ALL BUT NORTHERN PORTIONS OF THE FORECAST AREA. A FEW LIGHT
SHOWERS CONTINUE TO GRAZE FAR SOUTHERN COUNTIES AS A WEAK WAVE
ALOFT PASSES THROUGH THE LOWER OHIO VALLEY. TEMPS WERE GENERALLY
IN THE LOWER AND MIDDLE 70S AS OF 13Z.
FORECAST IN GOOD SHAPE THIS MORNING WITH JUST MINOR CHANGES
NEEDED. WEAK SURFACE WAVE ALONG SECONDARY FRONT NOTED ACROSS
NORTHEAST INDIANA WITH THE BOUNDARY EXTENDING SOUTHWEST INTO
CENTRAL ILLINOIS. THE BOUNDARY WILL PROGRESS SLOWLY SOUTH ACROSS
THE FORECAST AREA THROUGH THE AFTERNOON AND EVENING. WHILE FORCING
ALOFT REMAINS VERY WEAK...PRESENCE OF LOW LEVEL MOISTURE AND WEAK
INSTABILITY AHEAD OF THE BOUNDARY WILL LIKELY BE ENOUGH TO
GENERATE ISOLATED CONVECTION THROUGH THE AFTERNOON AND EARLY
EVENING...ESPECIALLY OVER THE SOUTHEAST HALF OF THE FORECAST AREA.
CURRENT HRRR CAPTURES THIS IDEA WELL...HINTING AT BEST POTENTIAL
FOR CONVECTIVE DEVELOPMENT OVER EASTERN COUNTIES WHICH MAKES SENSE
WITH SLIGHTLY BETTER FORCING ALOFT TO THE EAST OVER OHIO. WILL
MAINTAIN LOW CHANCE POPS THROUGH THE AFTERNOON OVER ALL BUT THE
NORTHERN WABASH VALLEY...AND INTO THE EVENING OVER FAR SOUTHERN
COUNTIES.
BUMPED UP HIGHS IN NORTHERN COUNTIES BY A DEGREE OR TWO...
ESPECIALLY WITH A MAINLY SUNNY START BEFORE CU FIELD DEVELOPS
LATER TODAY. OTHERWISE FORECAST HIGH TEMPS LOOK REASONABLE.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
HIGH PRESSURE WILL BUILD INTO CENTRAL INDIANA TONIGHT...INFLUENCING
THE AREA THROUGH SUNDAY NIGHT. THE NEXT CHANCE FOR ANY MEASURABLE
PRECIP WILL BE MONDAY/MONDAY NIGHT AS A COLD FRONT ENTERS FROM THE
NORTHWEST. THIS FRONT WILL COMBINE WITH SOME MOISTURE RETROGRADING
BACK INTO THE REGION. AS A RESULT...CHANCE POPS SEEM REASONABLE AT
THIS TIME DURING THE MONDAY/MONDAY NIGHT TIME FRAME.
TEMPS...MODELS ARE SHOWING SOME INCONSISTENCY WITH REGARD TO
CHANGING WEATHER PATTERN AT END OF SHORT TERM PERIOD. WENT WITH A
BLEND FROM TONIGHT THROUGH SUNDAY NIGHT...AND THEN LEANED TOWARD
THE WARMER GFS ON MONDAY TO CAPTURE ANY WARM AIR ADVECTION WITH A
SURFACE WARM FRONT.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
ISSUED AT 339 AM EDT SAT AUG 10 2013
ENSEMBLES INDICATE A RATHER STABLE WEATHER PATTERN DURING THIS
PERIOD. SUBTROPICAL RIDGE REMAINS ALONG THE GULF COAST/SOUTHERN
PLAINS REGION...WHILE UPPER TROUGHING CONTINUES OVER THE GREAT LAKES
AND NEW ENGLAND.
ENSEMBLES SUGGEST AN UPPER DISTURBANCE WILL BE IN THE PROCESS OF
PASSING OVER THE GREAT LAKES ON TUESDAY. WILL KEEP SOME CHANCE POPS
IN THE FORECAST ON TUESDAY TO COVER THIS FEATURE.
OTHERWISE...ENSEMBLES INDICATING LITTLE THREAT FOR PRECIPITATION FOR
THE REST OF THE EXTENDED...SO WILL GO DRY AFTER TUESDAY.
&&
.AVIATION /DISCUSSION FOR THE 101200Z TAFS/...
ISSUED AT 640 AM EDT SAT AUG 10 2013
SOME SPRINKLES POSSIBLE IN THE VICINITY OF THE TAF SITES THROUGH
ABOUT MID MORNING...OTHERWISE CONVECTIVE PARAMETERS SUGGEST ANY DEEP
CONVECTION WILL BE SOUTH OF THE TAF SITES TODAY.
SOME DIURNAL CLOUDS BASED AROUND 030 EXPECTED TO DEVELOP TOWARDS THE
MIDDAY HOURS.
NO VISIBILITY OR WIND ISSUES EXPECTED AT THE TAF SITES THROUGH
110000Z.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...TDUD
NEAR TERM...RYAN
SHORT TERM...TDUD
LONG TERM....JAS
AVIATION...JAS
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS DODGE CITY KS
315 PM CDT Sat Aug 10 2013
...updated long term...
.SYNOPSIS...
ISSUED AT 1220 PM CDT SAT AUG 10 2013
At 12z Saturday a 500mb -17c upper low was located just off the
northern California coast. Just east of this upper low the 500mb
low an upper level ridge axis extended from northern Idaho into
west Texas and 500mb thermal trough was located near the four
corners region. An 250mb jet extended from Baja California to New
Mexico. Across eastern Canada an upper low was located near Hudson
bay with one short wave trough located west of this upper low over
Manitoba. An area of higher 700mb dewpoints were located just
northeast of a +4 to +8c temperature gradient extended from
eastern Montana into northeast Kansas. A surface to 850mb high
this morning extended from Iowa into northeast New Mexico.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 217 PM CDT SAT AUG 10 2013
Southeast winds will continue overnight at 10 to 15 mph as a
trough of low pressure at the surface along the lee of the Rockies
deepens. This southeasterly flow will draw low to mid 60 dewpoints
back into southwest Kansas overnight which will give rise to some
patchy fog by morning. Bufr soundings however indicating the low
level moisture will be shallow and low level winds above the
surface will be at 15 to 20kts. In addition high clouds are
expected to spread into the area from the west after midnight. As
a result do not think widespread dense fog will be an issue late
tonight/early Sunday. Lows tonight in the low to mid 60s still
look on track based on the return of low level moisture and
increasing high clouds.
850mb temperatures warm 3-6c between 00z Sunday and 00z Monday,
especially in southwest Kansas. Both the NAM and GFS model
soundings suggest highs on Sunday will climb into the upper 80s to
lower 90s. The upper level disturbance that was located near the
four corners region at 12z Saturday is forecast to rotate around
the upper level ridge axis Saturday night and move across
northeast Colorado/northwest Kansas Sunday afternoon. Mid level
instability will be present across western Kansas by late day and
based on the track of this upper level system a few late day
thunderstorms will be possible after 21z across west central and
north central Kansas.
.LONG TERM...(Sunday night through Saturday)
ISSUED AT 309 PM CDT SAT AUG 10 2013
Thunderstorms are likely to build upscale Sunday night across north
central and central Kansas along the instability axis. The
thunderstorm activity would be driven/aided by a transient middle
level wave. farther southwest toward Elkhart and Liberal, any
convection would Likely be more isolated in nature rather than
widespread. precipitation chances will then be tapered off Monday
morning across the area, and ramped up again Monday evening in
association with the warm front straddled across central Kansas in
vicinity of the central High Plains surface low. best
precipitation/thunderstorm chances will again favor he evening hours
as storms this time may be driven though surface convergence
processes through the evening or overnight (timing of such a feature
is of low forecaster confidence). Temperature trends during this
timeframe range from warm across the region Monday to considerable
cooler behind the increasingly back door high pressure airmass by
Wednesday. By Wednesday, models are depicting considerable clouds if
not scattered upslope induced showers and thunderstorm during the day
as instability increases. The ALLBLEND forecast method carries 40
PoPs for this period.
As northwest flow is maintained aloft, thunderstorms driven/steered
from western initiation points cannot be ruled out anytime during the
period through the weekend. The better odds will be focused along
the high plains region from western Colorado, as diurnal driven
storms initiate along the Palmer divide and sangre de cristo
mountains, and into the Texas panhandle.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1220 PM CDT SAT AUG 10 2013
A trough of low pressure at the surface will develop along the
lee of the Rockies as a surface high slides east across central
Kansas. Southeast winds at around 10kts are expected this
afternoon and overnight. Status was observed across portions of
southwest Kansas earlier this morning and has been slow to erode.
Based on the latest RAP the low clouds will dissipate after 21z as
high level moisture begins to spread into the area from the west.
Moist upslope flow overnight may give rise to some areas of fog
and possibly status after midnight, however based on 12z soundings
IFR/LIFR vsbys from the fog is not anticipated.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 64 89 68 91 / 10 10 30 20
GCK 63 90 67 89 / 10 10 20 10
EHA 63 91 67 91 / 10 10 20 20
LBL 64 91 68 93 / 10 10 20 20
HYS 63 88 67 88 / 10 10 60 20
P28 67 89 71 93 / 10 10 60 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BURGERT
SHORT TERM...BURGERT
LONG TERM...RUSSELL
AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
218 PM CDT Sat Aug 10 2013
...UPDATED SHORT TERM DISCUSSION...
.SYNOPSIS...
ISSUED AT 1220 PM CDT SAT AUG 10 2013
At 12z Saturday a 500mb -17c upper low was located just off the
northern California coast. Just east of this upper low the 500mb
low an upper level ridge axis extended from northern Idaho into
west Texas and 500mb thermal trough was located near the four
corners region. An 250mb jet extended from Baja California to New
Mexico. Across eastern Canada an upper low was located near Hudson
bay with one short wave trough located west of this upper low over
Manitoba. An area of higher 700mb dewpoints were located just
northeast of a +4 to +8c temperature gradient extended from
eastern Montana into northeast Kansas. A surface to 850mb high
this morning extended from Iowa into northeast New Mexico.
&&
.SHORT TERM...(This evening through Sunday)
ISSUED AT 217 PM CDT SAT AUG 10 2013
Southeast winds will continue overnight at 10 to 15 mph as a
trough of low pressure at the surface along the lee of the Rockies
deepens. This southeasterly flow will draw low to mid 60 dewpoints
back into southwest Kansas overnight which will give rise to some
patchy fog by morning. Bufr soundings however indicating the low
level moisture will be shallow and low level winds above the
surface will be at 15 to 20kts. In addition high clouds are
expected to spread into the area from the west after midnight. As
a result do not think widespread dense fog will be an issue late
tonight/early Sunday. Lows tonight in the low to mid 60s still
look on track based on the return of low level moisture and
increasing high clouds.
850mb temperatures warm 3-6c between 00z Sunday and 00z Monday,
especially in southwest Kansas. Both the NAM and GFS model
soundings suggest highs on Sunday will climb into the upper 80s to
lower 90s. The upper level disturbance that was located near the
four corners region at 12z Saturday is forecast to rotate around
the upper level ridge axis Saturday night and move across
northeast Colorado/northwest Kansas Sunday afternoon. Mid level
instability will be present across western Kansas by late day and
based on the track of this upper level system a few late day
thunderstorms will be possible after 21z across west central and
north central Kansas.
.LONG TERM...(Sunday through Friday)
ISSUED AT 321 AM CDT SAT AUG 10 2013
Sunday:
Medium range models are in fair agreement with a frontal boundary located
across Nebraska Sunday afternoon with an associated lee trof across
eastern Colorado. These boundaries could be the impetus for convection
by late afternoon and evening. As such, have the highest precipitation
probabilities across the western and northern zones by afternoon and
then spreading values southeast in case a MCS comes into fruition. Southwest
Kansas will be in the warm sector with 850 hPa temperatures forecast
in the lower 20sC. This should support mix down temperatures around
the 90F mark. Overnight minimums will be more mild compared to the previous
morning as a result of low level dewpoint advection and southerly winds
with minimum values in the 60s/70sF.
Monday:
The aforementioned front will sink southward during Monday. Again, this
front could be the impetus for convection during the afternoon and evening.
Tried to put some temporal details in the precipitation chances as convection
will be diurnally driven and not much activity is expected during the
morning hours. We could see slightly cooler maximums with more upper
80sF, but confidence is low due to wherever the warm sector ends up.
Minimums will be similar to the night before - 60s/70sF.
Tuesday and beyond:
An upslope flow pattern is expected Tuesday. This favors cooler temperatures
and a continued threat for MCS formation. This activity should be more
orographically induced - drifting across the Kansas prairies during
the evening. Maximums Tuesday will be pleasant and in the lower 80sF.
Beyond Tuesday, there cold be more isolated storms through midweek.
Will continue with the weighted blend solution in the extended as far
as precipitation chances and temperatures are concerned.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1220 PM CDT SAT AUG 10 2013
A trough of low pressure at the surface will develop along the
lee of the Rockies as a surface high slides east across central
Kansas. Southeast winds at around 10kts are expected this
afternoon and overnight. Status was observed across portions of
southwest Kansas earlier this morning and has been slow to erode.
Based on the latest RAP the low clouds will dissipate after 21z as
high level moisture begins to spread into the area from the west.
Moist upslope flow overnight may give rise to some areas of fog
and possibly status after midnight, however based on 12z soundings
IFR/LIFR vsbys from the fog is not anticipated.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 64 88 68 88 / 10 30 30 40
GCK 63 89 67 90 / 10 30 40 40
EHA 63 91 67 91 / 10 30 40 40
LBL 64 91 68 92 / 10 30 30 40
HYS 63 88 67 85 / 10 30 40 40
P28 67 89 71 90 / 10 20 40 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BURGERT
SHORT TERM...BURGERT
LONG TERM...Sugden
AVIATION...BURGERT
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1225 PM CDT Sat Aug 10 2013
...UPDATED SYNOPSIS AND AVIATION DISCUSSION...
.SYNOPSIS...
ISSUED AT 1220 PM CDT SAT AUG 10 2013
At 12z Saturday a 500mb -17c upper low was located just off the
northern California coast. Just east of this upper low the 500mb
low an upper level ridge axis extended from northern Idaho into
west Texas and 500mb thermal trough was located near the four
corners region. An 250mb jet extended from Baja California to New
Mexico. Across eastern Canada an upper low was located near Hudson
bay with one short wave trough located west of this upper low over
Manitoba. An area of higher 700mb dewpoints were located just
northeast of a +4 to +8c temperature gradient extended from
eastern Montana into northeast Kansas. A surface to 850mb high
this morning extended from Iowa into northeast New Mexico.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 257 AM CDT SAT AUG 10 2013
Western Kansas will be in the cool, but modifying airmass in between
two frontal systems. As a result, high temperatures today will be
below average by about 7 to 9 degrees across much of the southwest
Kansas region. Today will be a much appreciated drying out day
(which is unbelievable to say amidst this long-term drought!) with
fairly light winds by western Kansas standards. The surface ridge
will shift to the southeast by afternoon and winds will become
southeasterly with an increase to the 10-15 mph range by mid to late
afternoon. There will terrain-generated thunderstorm activity across
Colorado this afternoon, and mid-upper level flow from the west will
carry any storms that form off the Palmer Divide east toward the
Kansas line by the evening hours. Should any storm survive that far
east, it is most likely to be across far northwest Kansas. As a
result of the very low probability of a storm surviving to
Morton-Stanton-Hamilton County, will decrease POPs to below 15
percent which will essentially come out as a dry forecast. Tonight,
the low level flow off the surface in the 925-850mb layer will
advect higher moisture air from Oklahoma into southern Kansas,
leading to low stratus development in the 09-12z time frame late
tonight. Will increase the Sky grids to mostly cloudy/cloudy
territory mainly across the eastern counties (along/east of Hwy
183). Low temperatures tonight will be in the lower 60s, which is a
bit lower than previous forecast.
.LONG TERM...(Sunday through Friday)
ISSUED AT 321 AM CDT SAT AUG 10 2013
Sunday:
Medium range models are in fair agreement with a frontal boundary located
across Nebraska Sunday afternoon with an associated lee trof across
eastern Colorado. These boundaries could be the impetus for convection
by late afternoon and evening. As such, have the highest precipitation
probabilities across the western and northern zones by afternoon and
then spreading values southeast in case a MCS comes into fruition. Southwest
Kansas will be in the warm sector with 850 hPa temperatures forecast
in the lower 20sC. This should support mix down temperatures around
the 90F mark. Overnight minimums will be more mild compared to the previous
morning as a result of low level dewpoint advection and southerly winds
with minimum values in the 60s/70sF.
Monday:
The aforementioned front will sink southward during Monday. Again, this
front could be the impetus for convection during the afternoon and evening.
Tried to put some temporal details in the precipitation chances as convection
will be diurnally driven and not much activity is expected during the
morning hours. We could see slightly cooler maximums with more upper
80sF, but confidence is low due to wherever the warm sector ends up.
Minimums will be similar to the night before - 60s/70sF.
Tuesday and beyond:
An upslope flow pattern is expected Tuesday. This favors cooler temperatures
and a continued threat for MCS formation. This activity should be more
orographically induced - drifting across the Kansas prairies during
the evening. Maximums Tuesday will be pleasant and in the lower 80sF.
Beyond Tuesday, there cold be more isolated storms through midweek.
Will continue with the weighted blend solution in the extended as far
as precipitation chances and temperatures are concerned.
&&
.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
ISSUED AT 1220 PM CDT SAT AUG 10 2013
A trough of low pressure at the surface will develop along the
lee of the Rockies as a surface high slides east across central
Kansas. Southeast winds at around 10kts are expected this
afternoon and overnight. Status was observed across portions of
southwest Kansas earlier this morning and has been slow to erode.
Based on the latest RAP the low clouds will dissipate after 21z as
high level moisture begins to spread into the area from the west.
Moist upslope flow overnight may give rise to some areas of fog
and possibly status after midnight, however based on 12z soundings
IFR/LIFR vsbys from the fog is not anticipated.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 84 62 88 68 / 10 10 30 30
GCK 84 62 89 67 / 10 10 30 40
EHA 86 64 91 67 / 10 10 30 40
LBL 86 62 91 68 / 10 10 30 30
HYS 83 63 88 67 / 10 10 30 40
P28 85 65 89 71 / 10 10 20 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BURGERT
SHORT TERM...UMSCHEID
LONG TERM...Sugden
AVIATION...BURGERT
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
205 AM EDT SAT AUG 10 2013
.UPDATE...
ISSUED AT 200 AM EDT SAT AUG 10 2013
HAVE ADJUSTED THE POP AND WX GRIDS TO REFLECT THE ONGOING CONVECTION
IN THE FAR NORTH AND SOME NEWER CELLS GOING UP IN THE CUMBERLAND
VALLEY. RUN TO RUN CONSISTENCY FROM THE HRRR MAKES ITS SOLUTION
QUESTIONABLE SO HAVE ONLY PARTIALLY SHADED THE FORECAST TOWARD ITS
IDEAS THAT ARE IN LINE WITH THE 00Z NAM12 AND CURRENT RADAR SCOPE.
ALSO...FINE TUNED THE T AND TD GRIDS PER THE LATEST OBS AND TRENDS.
UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS WITH A FRESHENED
ZFP TO FOLLOW.
UPDATE ISSUED AT 720 PM EDT FRI AUG 9 2013
SHOWERS AND STORMS CONTINUE TO EXPAND ACROSS CENTRAL AND SOUTHERN
KENTUCKY WITH IMPRESSIVE RAINFALL RATES NEAR 2 INCHES PER HOUR FAIRLY
COMMON. GIVEN SOME LOWER FLASH FLOOD GUIDANCE VALUES IN SOME
AREAS...THIS COULD MEAN WE MAY EXCEED FLASH FLOOD GUIDANCE IN SOME
PLACES. THUS...FLOODING WILL CONTINUE TO BE A THREAT THROUGH THIS
EVENING. OPTING TO NOT FLIP FLOP ON ANY WATCH AND JUST ISSUE ANY
WARNINGS AS NEEDED. LOOKS LIKE THE SOUTHERN HALF OF THE CWA WILL BE
UNDER THE BIGGEST THREAT FOR ANY FLOODING. STILL UNCERTAIN WITH HOW
THE REST OF THE NIGHT WILL PAN OUT...BUT THE NEXT SEVERAL HOURS LOOKS
VERY ACTIVE WITH LOTS OF RAIN FOR SOME OF THE AREA. WILL UPDATE GRIDS
TO REFLECT THE BETTER RAIN CHANCES ACROSS THE SOUTH.
UPDATE ISSUED AT 606 PM EDT FRI AUG 9 2013
WITH THE FLOOD WATCH NOW HISTORY...SHOWERS AND STORMS ARE RAMPING UP
ACROSS SOUTHERN AND CENTRAL KENTUCKY. DO NOT HAVE A REAL GOOD FEEL
FOR HOW THINGS WILL EVOLVE THIS EVENING. MODELS ARE ALL HANDLING THIS
SYSTEM VERY POORLY...BUT BASED ON CURRENT RADAR TRENDS...IT LOOKS
LIKE SOME BETTER RAIN SHOULD MOVE INTO MUCH OF EASTERN KENTUCKY INTO
THE MID TO LATE EVENING HOURS. SOME OF THIS MAY WEAKEN AS WE LOSE THE
BETTER INSTABILITY...BUT WITH THE FRONTAL BOUNDARY PUSHING INTO
NORTHERN KENTUCKY...WE MAY SEE STUFF AT LEAST IN THE NORTH STAY
ACTIVE WELL INTO THE NIGHT. AGAIN...UPDATED WILL BE NEEDED THROUGH
THE NIGHT AS PRECIPITATION TRENDS BECOME BETTER DEFINED. FOR
NOW...GOING TO UPDATE THE NEXT FEW HOURS AND BLEND INTO THE OLD
FORECAST. MAY NEED TO WATCH THE POTENTIAL FOR FLOODING GIVEN THE
IMPRESSIVE RAINFALL RATES BEING RECEIVED UPSTREAM OVER SOUTH CENTRAL
KENTUCKY. GRIDS HAVE BEEN SENT TO THE NDFD.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 410 PM EDT FRI AUG 9 2013
A LINE OF CONVECTION WAS AT THE NORTHERN EDGE OF THE FORECAST AREA AT
MID AFTERNOON...WITH ADDITIONAL SCATTERED SHOWERS/THUNDERSTORMS OVER
TN. MOST OF THE FORECAST AREA WAS QUIET...ALTHOUGH A FEW SHOWERS WERE
STRUGGLING TO GET GOING. FORECAST SOUNDINGS LOOKED FAVORABLE FOR
ACTIVITY LATE TODAY...AND WILL CONTINUE WITH THIS IN THE FORECAST.
HOWEVER...THE BEST SHOT AT RAIN LOOKS LIKE IT WILL BE TONIGHT INTO
EARLY SATURDAY. MODELS IN GENERAL HAVE POINTED TO THIS...BUT HAVE
SHOWN POOR AGREEMENT/CONSISTENCY ON THE POTENTIAL FOR HEAVY PRECIP.
IN LIGHT OF THIS AND HISTORY SINCE THE WATCH WAS ISSUED...WILL CANCEL
THE WATCH WHICH WAS OTHERWISE SET TO EXPIRE AT 8 PM. WE ARE NOT
COMPLETELY OUT OF THE WOODS WITH THE THREAT...BUT CONFIDENCE IS NOT
THERE TO WARRANT AN EXTENSION.
THE FRONTAL BOUNDARY WHICH HAS BEEN HUNG UP JUST TO OUR NORTH MAY
SINK A BIT FURTHER SOUTH ON SATURDAY NIGHT...AND
SHOWERS/THUNDERSTORMS WILL STILL BE POSSIBLE. HOWEVER...GUIDANCE IN
GENERAL IS LIGHTER ON PRECIP AND MOS IS LOWER ON POPS...AND FOLLOWED
THEIR LEAD FOR THE FORECAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 410 PM EDT FRI AUG 9 2013
PRETTY GOOD AGREEMENT BETWEEN THE LONG TERM MODELS. THE CONSENSUS IS
FOR A LARGE UPPER LEVEL TROUGH TO MOVE ACROSS THE NORTHERN CONUS
FROM SUNDAY ONWARD...WITH ITS ATTENDANT SURFACE COLD FRONT GETTING
DRAGGED ACROSS THE OHIO AND TENNESSEE VALLEYS. BASED ON THE OVERALL
MOISTURE DISTRIBUTION...BOTH AT THE SURFACE AND ALOFT...ACROSS THE
AREA...SCATTERED SHOWERS AND STORMS WILL BE ON TAP DURING FRONTAL
PASSAGE. THE FRONT COULD GET HUNG UP A BIT AS IT ENCOUNTERS THE
APPALACHIAN MOUNTAINS...AND AS A RIDGE STUBBORNLY REMAINS IN PLACE
OFF THE SOUTHEAST COAST. A SURFACE RIDGE WILL FINALLY STRENGTHEN
ENOUGH BY THE END OF THE WEEK TO PUSH THE FRONT...AND ITS
PRECIPITATION OUT OF THE AREA. TEMPERATURES DURING THE UPCOMING WORK
WEEK WILL RUN AT OR SLIGHTLY BELOW NORMAL DUE TO EXTENSIVE CLOUD
COVER AND PERIODIC PRECIPITATION.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 205 AM EDT SAT AUG 10 2013
DEVELOPING SHOWERS AND THUNDERSTORMS MAY AFFECT SOME OF THE TAF SITES
DURING THE NEXT FEW HOURS...BUT MOST WILL STAY IN THE CLEAR...ASIDE
FROM SOME PATCHY...MVFR FOG. EXPECT ADDITIONAL SHOWERS AND
THUNDERSTORMS TO TAKE SHAPE LATER IN THE MORNING. ANY OF THESE
STORMS...INTO THE DAY SATURDAY...WILL DROP VISIBILITIES AND CEILINGS
TO MVFR OR BRIEFLY LOWER AT THE TAF SITES. THE CONVECTION OF THE DAY
IS EXPECTED TO SETTLE DOWN LATER SATURDAY EVENING. OUTSIDE OF ANY
NEARBY STORM...WINDS WILL BE LIGHT AND VARIABLE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GREIF
SHORT TERM...HAL
LONG TERM...AR
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
144 AM EDT Sat Aug 10 2013
...Updated Aviation Discussion...
...Forecast Update...
Issued at 901 PM EDT Fri Aug 9 2013
Cluster of showers and storms currently across south central
Kentucky will continue to head off to the ENE through the next few
hours. Although trends with these storms have weakened, periods of
intense rainfall can still occur, especially with repeated
thunderstorms over the area. Use caution if traveling as flooding
problems will still be possible through late evening.
A pocket of drier air evident on water vapor imagery is working into
the region behind this last cluster of precipitation. Will go dry
for much of the late evening into the early morning hours, before
deeper moisture will again surge into the area and small chances for
a shower or storm will return. The concern for this dry period will
be for fog formation as skies will become mostly clear across much
of Kentucky. With the recent heavy rainfall, fog and even dense fog
will likely form. Actually already seeing some fog form on webcams.
Have include fog mention in the grids for now, but may need to
update if obs start showing dense fog development. As we move into
the pre-dawn hours, will likely see thicker cloud cover move back
over, which should improve the situation.
Issued at 533 PM EDT Fri Aug 9 2013
Updated the grids to reflect higher coverage of showers and storms
across SW portions of the CWA. Issued a Flood Advisory for areas
around Bowling Green as some training of showers and storms with
rainfall rates over 2 inches per hour at times will overspread the
area. Will need to watch for Flash Flood Warnings in the region over
the next couple of hours. Will also keep our eye on a cluster of
storms moving into the western fringes of our CWA in a couple of
hours. A few severe reports have come from the strongest storm,
however expect a weakening trend as the cluster moves in. Overall,
will mention numerous showers and storms early this evening in areas
where the biggest clusters are located, with isolated to scattered
coverage elsewhere. Please be aware that very heavy rainfall is
likely with any shower or storm and quick ponding of water on
roadways will occur.
.SHORT TERM (Now through Saturday Night)...
Issued at 305 PM EDT Fri Aug 9 2013
A line of showers and thunderstorms have begun to form along the
frontal boundary, currently draped along the Ohio River. As has been
the case this week, these are efficient rain producers, dumping a
lot of rain in a short amount of time. Traffic cameras in the
Louisville metro along with obs from SDF confirm the reduced
visibilities accompanying these cells. Thankfully, the line has been
moving relatively quickly off to the east-southeast so unless the
line really fills in, setting up a potential training effect,
flooding shouldn`t be a major concern, especially in north-central
KY where the rain has been much more hit and miss as of late. If it
is able to hold together and makes its way into the Bluegrass
region, there could be some localized problems since FFG is much
lower there due to the recent heavy rains and already saturated
soils. Unfortunately, the models aren`t handling it very well with
the exception of the latest NAM (but its performance this week has
been less than stellar) so its tough to get a solid idea of how this
will play out. While the HRRR doesn`t necessarily depict it well,
this has been one of the top performing models under this regime
and its showing scattered cells developing across much of the center
of the commonwealth. Later tonight, a mid-level wave traverses
through and the HRRR grabs onto it, bringing a cluster of showers
and embedded thunderstorms through northern KY and southern IN. This
may be a bit bullish but it would be the last hurrah for the
northern half of the forecast area as the boundary slowly sinks
south (assuming this scenario holds true).
By tomorrow, the focus for convection shifts to the south once again
along the quasi-stationary boundary. As it stands right now, any
storms that fire up during the heat of the day (despite the
continued cloud cover) should wane after sunset Saturday, allowing
for most of the area to remain dry. Under light to calm winds and
lingering low-level moisture, patchy fog could be a factor for not
only tonight (wherever it doesn`t rain) but for tomorrow night as
well. Overnight lows for both nights will range from the upper 60s
to the lower 70s from north to south, respectively. Under the
aforementioned cloud cover, highs tomorrow will again be below
normal, primarily in the mid 80s. Expect this tropical-feeling
airmass to remain in place for the entirety of this forecast period.
.LONG TERM (Sunday through Friday)...
Issued at 312 PM EDT Fri Aug 9 2013
The start of the long term period will feature generally zonal upper
flow, which will transition to an eastern trough/western ridge by
the end of the long term period. This pattern shift will allow for
drier conditions and cooler/less humid air by the middle of next
week.
A quasi-stationary frontal boundary will be draped from southwest to
northeast across southern Kentucky on Sunday. This will serve as
the focus for showers and thunderstorms to continue, mainly across
southern Kentucky as a shortwave trough rides along the boundary and
brings enhanced vertical motion. As winds turn northerly across
southern Indiana and northern Kentucky due to incoming high
pressure, think enough dry air will work in to actually keep much of
Sunday dry for those regions.
On Sunday night, the surface high will scoot east as another
shortwave trough dives through the Great Lakes region. Guidance
suggests this wave will pull the quasi-stationary front back north
which would give much more of central and northern KY decent
rainfall chances. However, am a bit skeptical of this solution as
the progged system does not appear strong enough to force the front
northward (especially if it`s continually being convectively
reinforced further south). Therefore, the more widespread activity
will likely remain across southern KY, with a general lull in
activity across northern KY and southern Indiana. Given the
continued moist atmosphere south of the front, localized flooding
will need to continue to be watched especially if areas receive
heavy rainfall through the short term period.
By Monday night into Tuesday, another surface front will approach
from the northwest. This front looks much more progressive as the
upper-level flow begins to transition to more northwesterly. As
mentioned in the previous discussion, am a bit skeptical on just how
much moisture will remain ahead of this secondary front, thus will
continue with 30-40 pops as it passes through on Tuesday. Given
the likely moist bias in guidance, instability along this front will
be less than currently progged, thus do not expect severe weather.
However, the drier air working in will help support a few healthy
downdrafts, which may lead to some sub-severe gusts in the
heavier storm cores.
The front will clear the region by Tuesday night, allowing Canadian
high pressure to build into the Ohio Valley. This will bring
welcomed relief from the muggy airmass we have seen of late, as
temperatures fall into the upper 70s/lower 80s with dewpoints in the
50s and lower 60s. This pleasant airmass will also get rid of any
additional storm potential, with dry weather expected Wednesday
through at least the end of next week.
&&
.AVIATION (06Z TAF Update)...
Issued at 140 AM EDT Sat Aug 10 2013
Surface analysis reveals a quasi-stationary boundary extending from
central Arkansas northeastward through central Kentucky and into
southern Ohio. Showers and isolated thunderstorms have redeveloped
along this boundary, with activity stretching from the Bluegrass, to
Louisville, and southwestward to Bowling Green. This activity should
be around through much of the early morning hours, with perhaps the
best coverage east and near the Ohio River toward dawn. Will carry
VCSH for all sites. Activity should diminish through the morning and
early afternoon hours, with perhaps additional development in the
afternoon. Will only try to nail down the next 12 hours as
confidence is low.
Cloud cover has build back across the sites, which is helping keep
visibilities manageable. Latest guidance continues to indicate at
least MVFR vis and cig restrictions for all sites as dawn nears. LEX
has dropped to LIFR already, but may improve near dawn as this early
morning precip nears that area. Otherwise, will hint at restrictions
in the SDF and BWG TAFs, especially with that boundary in the area.
If clouds diminish, then worse conditions could be experienced. Will
continue to monitor as clouds may be breaking up just to our west.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
Update.........BJS
Short Term.....LG
Long Term......KJD
Aviation.......MJP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
134 PM EDT SAT AUG 10 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT SAT AUG 10 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
QUEBEC RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. THE MOST
PROMINENT UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER SW SASK. AT THE
SFC...A WEAK TROUGH EXTENDED FROM JAMES BAY INTO NE LAKE SUPERIOR
WHILE A RIDGE EXTENDED FROM ND INTO MN AND IA. IR LOOP SHOWED MAINLY
CLEAR SKIES OVER UPPER MICHIGAN WHICH HAS ALLOWED TEMPS TO DROP INTO
THE LOWER TO MID 40S INLAND. THE NRN EDGE OF A MORE EXTENSIVE AREA OF
CLOUD HAS REMAINED TO THE WEST AND SOUTH FROM NEAR ASX TO MNM.
TODAY...WITH THE WEAK 850-700 MB THERMAL TROUGH REMAINING NEAR THE
AREA...EXPECT SCT/BKN CU TO AGAIN DEVELOP THIS AFTERNOON. EVEN WITH
PROMINENT LAKE BREEZE BOUNDARIES THIS AFTERNOON IN THE RELATIVELY
LIGHT WIND FIELD...A STRONG CAP/INVERSION AROUND 700 MB...PER MDLS
SOUNDINGS AND AREA 00Z RAOBS...AND DRY LOW LEVELS WILL INHIBIT ANY
PCPN. NO MORE THAN A BRIEF SPRINKLE WOULD BE EXPECTED OUT OF THE
RELATIVELY SHALLOW CONVECTIVE CLOUDS. TEMPS WILL CLIMB TO NEAR
NORMAL...IN THE LOWER TO MID 70S.
TONIGHT...THE SASK SHRTWV WILL APPROACH UPPER MI TONIGHT BUT ANY
PCPN WITH THIS FEATURE IS EXPECTED TO REMAIN TO THE W OF THE CWA.
THE SIGNFICANT PCPN WILL REMAIN WELL TO THE SOUTH...CLOSER TO THE
850 MB FRONT OVER SRN MN. INCREASING MID CLOUDS LATE WILL KEEP TEMPS
FROM FALLING OFF AS MUCH WITH MIN READINGS IN THE MID 40S TO LOWER
50S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 358 AM EDT SAT AUG 10 2013
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED SUNDAY
AFTERNOON AND MONDAY BEFORE BROAD HIGH PRESSURE GAINS CONTROL OF THE
REGION AND BRINGS AN EXTENDED PERIOD OF DRY WEATHER THROUGH THE
UPCOMING WEEK. TEMPERATURES WILL CONTINUE TO BE SLIGHTLY BELOW
NORMAL...WITH A COUPLE CHILLY NIGHTS EXPECTED FOR THE FIRST PART OF
THE WEEK.
SUNDAY...A BROAD MID-LEVEL TROUGH CENTERED OVER FAR NORTHERN
ONTARIO WILL BE MAKING A SOUTHWARD PUSH AT THE START OF THE PERIOD.
MAIN FORECAST FOCUS CONTINUES TO BE ON THE POTENTIAL FOR AFTERNOON
SHOWERS AND THUNDER ACROSS INTERIOR PORTIONS OF THE CWA. MODEL
GUIDANCE HAS BEEN QUITE PERSISTENT FOR SEVERAL NIGHTS NOW WITH
ADVERTISING THE PASSAGE OF A LEAD SHORTWAVE ACROSS UPPER MI ON
SUNDAY AFTERNOON AND EVENING. THIS WAVE IS A RESULT OF PHASING
BETWEEN SMALL PIECES OF ENERGY FROM WESTERN CANADA AND THE LARGER
TROUGH. THE ECMWF AND GEM ARE THE QUICKEST...AND HAVE THE TROUGH
OUTRUNNING PEAK HEATING BY CLEARING THE EASTERN CWA BY MID
AFTERNOON. THE NAM/LOCAL WRF/GFS ARE SLOWER...AND BRING THE WAVE
ACROSS THE CENTRAL CWA AROUND EARLY AFTERNOON. SUBTLE NW FLOW
FEATURES CAN BE QUITE FICKLE THIS TIME OF YEAR...SO AM NOT TOO
CONFIDENT IN JUMPING ON EITHER SOLUTION ATTM. GIVEN COMPETING
DYNAMICS BETWEEN THE MID-LEVEL WAVE AND THE LEFT ENTRANCE OF AN 80
KT UPPER JET...WILL MAINTAIN THE FOCUS FOR PRECIP CHANCES ACROSS THE
SOUTH CENTRAL AND INTERIOR EAST WHERE ASSISTANCE FROM LAKE BREEZE
CONVERGENCE WILL BOOST DIURNAL ACTIVITY.
ONE CONCERN WITH THUNDER POTENTIAL OVER THE PAST COUPLES DAYS HAS
BEEN LOWER INSTABILITY DUE TO CLOUDS FROM CONVECTION TO THE SOUTH.
WITH MLCAPE PEAKING AT ONLY 500 J/KG FAR SOUTH CENTRAL...THUNDER
COVERAGE WILL BE LIMITED. A DRY SUBCLOUD LAYER COULD STILL RESULT IN
SOME GUSTY WINDS TO 35 MPH WITH ANY SHOWERS THOUGH AS DOWNDRAFT CAPE
WILL BE OVER 500 J/KG.
SUNDAY NIGHT AND MONDAY...ANY ACTIVITY SUNDAY AFTERNOON SHOULD
DIMINISH WITH THE PASSAGE OF THE WAVE AND LOSS OF DAYTIME HEATING. A
WEAK SFC TROUGH ASSOCIATED WITH THE MID-LEVEL TROUGH WILL STILL BE
DRIFTING ACROSS THE EASTERN CWA INTO THE OVERNIGHT HOURS...BUT DO
NOT EXPECT ANY LINGERING SHOWERS GIVEN WEAK LIFT AND DRIER AIR. THE
MAIN TROUGH IS THEN PROGGED TO CROSS THE CWA DURING THE DAY ON
MONDAY. MID-LEVEL Q-VECTOR CONVERGENCE WITH A DECENT UPPER-LEVEL
NEGATIVE PV ANOMALY WILL BRING MODEST LIFT ACROSS THE NORTHERN CWA
AND LAKE SUPERIOR MONDAY AFTERNOON. ONCE AGAIN...DAYTIME HEATING
WILL ASSIST WITH PRECIP COVERAGE IN THE AFTERNOON. DO NOT EXPECT ANY
MORE COVERAGE THAN SUNDAY AFTERNOON AS MID-LEVEL CAPPING BEHIND
SUNDAYS TROUGH WILL LIMIT VERTICAL GROWTH OF ANY SHOWERS. WILL
MAINTAIN GOING FORECAST WITH BEST CHANCE POPS AND SLIGHT CHANCE OF
THUNDER SOUTH-CENTRAL AND INTERIOR EAST IN THE AFTERNOON.
TUESDAY THROUGH FRIDAY...HIGH PRESSURE WILL BUILD INTO THE CWA FROM
THE WEST BEGINNING MONDAY NIGHT AND SETTLE OVER THE REGION TUESDAY
NIGHT. PWAT VALUES OF 0.5 INCHES OR LESS AND LIGHT WINDS WILL LEAD
TO GREAT RADIATIONAL COOLING BOTH MONDAY AND TUESDAY NIGHTS.
GUIDANCE THAT HAS VERIFIED THE BEST OVER RECENT COOL NIGHTS PRODUCES
MIN TEMPS WELL INTO THE 40S INLAND...ESPECIALLY TUESDAY NIGHT. COULD
EVEN SEE SOME UPPER 30S TUESDAY NIGHT AT THE TYPICAL COOL
SPOTS...BUT DID NOT GO THAT LOW QUITE YET GIVEN UNCERTAINTY IN THE
EXACT PLACEMENT OF THE SFC HIGH. OVERALL...LOWERED TEMPS BY A COUPLE
DEGREES FOR BOTH NIGHTS. ALSO ADDED SOME PATCHY FOG ACROSS THE
INTERIOR WEST HALF MONDAY NIGHT SINCE THEY WILL HAVE SEEN A FEW
SHOWERS ON MONDAY AFTERNOON AND CROSSOVER TEMPS SHOULD BE SURPASSED
BY SEVERAL DEGREES.
ANOTHER WEAK TROUGH AXIS FROM THE MAIN EASTERN CANADIAN TROUGH WILL
SKIRT NE LAKE SUPERIOR THURSDAY. WITH MOISTURE LACKING AND BEST
DYNAMICS WELL NORTHEAST...KEPT PRECIP OUT OF THE FORECAST. A
PACIFIC-BASED WAVE COULD BEGIN AFFECTING THE WEST BY LATE
FRIDAY...BUT MODEL CONSISTENCY HAS BEEN POOR SO CONFIDENCE IS LOW IN
ANY PRECIP LATE IN THE WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 134 PM EDT SAT AUG 10 2013
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES THIS FORECAST
PERIOD. THERE IS A CHANCE OF SOME ISOLATED TO SCATTERED RAIN SHOWERS
AT IWD AND SAW TOWARD THE END OF THE TAF PERIOD...BUT CONFIDENCE IS
TOO LOW AT THIS TIME TO INCLUDE IN THE FORECAST.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 500 AM EDT SAT AUG 10 2013
HIGH PRESSURE MOVING INTO THE WRN GREAT LAKES WILL BRING RELATIVELY
LIGHT WINDS BELOW 20 KNOTS THROUGH THE WEEKEND. A WEAK TROUGH WILL
CROSS THE GREAT LAKES MONDAY...BUT AGAIN...WINDS WILL REMAIN LESS
THAN 20 KNOTS. HIGH PRESSURE WILL RESUME CONTROL OF THE WRN GREAT
LAKES TUESDAY THROUGH THE END OF THE WEEK TO KEEP WINDS GENERALLY
LIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KLUBER
AVIATION...TITUS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
745 AM EDT SAT AUG 10 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT SAT AUG 10 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
QUEBEC RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. THE MOST
PROMINENT UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER SW SASK. AT THE
SFC...A WEAK TROUGH EXTENDED FROM JAMES BAY INTO NE LAKE SUPERIOR
WHILE A RIDGE EXTENDED FROM ND INTO MN AND IA. IR LOOP SHOWED MAINLY
CLEAR SKIES OVER UPPER MICHIGAN WHICH HAS ALLOWED TEMPS TO DROP INTO
THE LOWER TO MID 40S INLAND. THE NRN EDGE OF A MORE EXTENSIVE AREA OF
CLOUD HAS REMAINED TO THE WEST AND SOUTH FROM NEAR ASX TO MNM.
TODAY...WITH THE WEAK 850-700 MB THERMAL TROUGH REMAINING NEAR THE
AREA...EXPECT SCT/BKN CU TO AGAIN DEVELOP THIS AFTERNOON. EVEN WITH
PROMINENT LAKE BREEZE BOUNDARIES THIS AFTERNOON IN THE RELATIVELY
LIGHT WIND FIELD...A STRONG CAP/INVERSION AROUND 700 MB...PER MDLS
SOUNDINGS AND AREA 00Z RAOBS...AND DRY LOW LEVELS WILL INHIBIT ANY
PCPN. NO MORE THAN A BRIEF SPRINKLE WOULD BE EXPECTED OUT OF THE
RELATIVELY SHALLOW CONVECTIVE CLOUDS. TEMPS WILL CLIMB TO NEAR
NORMAL...IN THE LOWER TO MID 70S.
TONIGHT...THE SASK SHRTWV WILL APPROACH UPPER MI TONIGHT BUT ANY
PCPN WITH THIS FEATURE IS EXPECTED TO REMAIN TO THE W OF THE CWA.
THE SIGNFICANT PCPN WILL REMAIN WELL TO THE SOUTH...CLOSER TO THE
850 MB FRONT OVER SRN MN. INCREASING MID CLOUDS LATE WILL KEEP TEMPS
FROM FALLING OFF AS MUCH WITH MIN READINGS IN THE MID 40S TO LOWER
50S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 358 AM EDT SAT AUG 10 2013
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED SUNDAY
AFTERNOON AND MONDAY BEFORE BROAD HIGH PRESSURE GAINS CONTROL OF THE
REGION AND BRINGS AN EXTENDED PERIOD OF DRY WEATHER THROUGH THE
UPCOMING WEEK. TEMPERATURES WILL CONTINUE TO BE SLIGHTLY BELOW
NORMAL...WITH A COUPLE CHILLY NIGHTS EXPECTED FOR THE FIRST PART OF
THE WEEK.
SUNDAY...A BROAD MID-LEVEL TROUGH CENTERED OVER FAR NORTHERN
ONTARIO WILL BE MAKING A SOUTHWARD PUSH AT THE START OF THE PERIOD.
MAIN FORECAST FOCUS CONTINUES TO BE ON THE POTENTIAL FOR AFTERNOON
SHOWERS AND THUNDER ACROSS INTERIOR PORTIONS OF THE CWA. MODEL
GUIDANCE HAS BEEN QUITE PERSISTENT FOR SEVERAL NIGHTS NOW WITH
ADVERTISING THE PASSAGE OF A LEAD SHORTWAVE ACROSS UPPER MI ON
SUNDAY AFTERNOON AND EVENING. THIS WAVE IS A RESULT OF PHASING
BETWEEN SMALL PIECES OF ENERGY FROM WESTERN CANADA AND THE LARGER
TROUGH. THE ECMWF AND GEM ARE THE QUICKEST...AND HAVE THE TROUGH
OUTRUNNING PEAK HEATING BY CLEARING THE EASTERN CWA BY MID
AFTERNOON. THE NAM/LOCAL WRF/GFS ARE SLOWER...AND BRING THE WAVE
ACROSS THE CENTRAL CWA AROUND EARLY AFTERNOON. SUBTLE NW FLOW
FEATURES CAN BE QUITE FICKLE THIS TIME OF YEAR...SO AM NOT TOO
CONFIDENT IN JUMPING ON EITHER SOLUTION ATTM. GIVEN COMPETING
DYNAMICS BETWEEN THE MID-LEVEL WAVE AND THE LEFT ENTRANCE OF AN 80
KT UPPER JET...WILL MAINTAIN THE FOCUS FOR PRECIP CHANCES ACROSS THE
SOUTH CENTRAL AND INTERIOR EAST WHERE ASSISTANCE FROM LAKE BREEZE
CONVERGENCE WILL BOOST DIURNAL ACTIVITY.
ONE CONCERN WITH THUNDER POTENTIAL OVER THE PAST COUPLES DAYS HAS
BEEN LOWER INSTABILITY DUE TO CLOUDS FROM CONVECTION TO THE SOUTH.
WITH MLCAPE PEAKING AT ONLY 500 J/KG FAR SOUTH CENTRAL...THUNDER
COVERAGE WILL BE LIMITED. A DRY SUBCLOUD LAYER COULD STILL RESULT IN
SOME GUSTY WINDS TO 35 MPH WITH ANY SHOWERS THOUGH AS DOWNDRAFT CAPE
WILL BE OVER 500 J/KG.
SUNDAY NIGHT AND MONDAY...ANY ACTIVITY SUNDAY AFTERNOON SHOULD
DIMINISH WITH THE PASSAGE OF THE WAVE AND LOSS OF DAYTIME HEATING. A
WEAK SFC TROUGH ASSOCIATED WITH THE MID-LEVEL TROUGH WILL STILL BE
DRIFTING ACROSS THE EASTERN CWA INTO THE OVERNIGHT HOURS...BUT DO
NOT EXPECT ANY LINGERING SHOWERS GIVEN WEAK LIFT AND DRIER AIR. THE
MAIN TROUGH IS THEN PROGGED TO CROSS THE CWA DURING THE DAY ON
MONDAY. MID-LEVEL Q-VECTOR CONVERGENCE WITH A DECENT UPPER-LEVEL
NEGATIVE PV ANOMALY WILL BRING MODEST LIFT ACROSS THE NORTHERN CWA
AND LAKE SUPERIOR MONDAY AFTERNOON. ONCE AGAIN...DAYTIME HEATING
WILL ASSIST WITH PRECIP COVERAGE IN THE AFTERNOON. DO NOT EXPECT ANY
MORE COVERAGE THAN SUNDAY AFTERNOON AS MID-LEVEL CAPPING BEHIND
SUNDAYS TROUGH WILL LIMIT VERTICAL GROWTH OF ANY SHOWERS. WILL
MAINTAIN GOING FORECAST WITH BEST CHANCE POPS AND SLIGHT CHANCE OF
THUNDER SOUTH-CENTRAL AND INTERIOR EAST IN THE AFTERNOON.
TUESDAY THROUGH FRIDAY...HIGH PRESSURE WILL BUILD INTO THE CWA FROM
THE WEST BEGINNING MONDAY NIGHT AND SETTLE OVER THE REGION TUESDAY
NIGHT. PWAT VALUES OF 0.5 INCHES OR LESS AND LIGHT WINDS WILL LEAD
TO GREAT RADIATIONAL COOLING BOTH MONDAY AND TUESDAY NIGHTS.
GUIDANCE THAT HAS VERIFIED THE BEST OVER RECENT COOL NIGHTS PRODUCES
MIN TEMPS WELL INTO THE 40S INLAND...ESPECIALLY TUESDAY NIGHT. COULD
EVEN SEE SOME UPPER 30S TUESDAY NIGHT AT THE TYPICAL COOL
SPOTS...BUT DID NOT GO THAT LOW QUITE YET GIVEN UNCERTAINTY IN THE
EXACT PLACEMENT OF THE SFC HIGH. OVERALL...LOWERED TEMPS BY A COUPLE
DEGREES FOR BOTH NIGHTS. ALSO ADDED SOME PATCHY FOG ACROSS THE
INTERIOR WEST HALF MONDAY NIGHT SINCE THEY WILL HAVE SEEN A FEW
SHOWERS ON MONDAY AFTERNOON AND CROSSOVER TEMPS SHOULD BE SURPASSED
BY SEVERAL DEGREES.
ANOTHER WEAK TROUGH AXIS FROM THE MAIN EASTERN CANADIAN TROUGH WILL
SKIRT NE LAKE SUPERIOR THURSDAY. WITH MOISTURE LACKING AND BEST
DYNAMICS WELL NORTHEAST...KEPT PRECIP OUT OF THE FORECAST. A
PACIFIC-BASED WAVE COULD BEGIN AFFECTING THE WEST BY LATE
FRIDAY...BUT MODEL CONSISTENCY HAS BEEN POOR SO CONFIDENCE IS LOW IN
ANY PRECIP LATE IN THE WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 743 AM EDT SAT AUG 10 2013
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES THIS FORECAST
PERIOD. KSAW WILL SEE A NE LAKE BREEZE SAT AFTERNOON. &&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 500 AM EDT SAT AUG 10 2013
HIGH PRESSURE MOVING INTO THE WRN GREAT LAKES WILL BRING RELATIVELY
LIGHT WINDS BELOW 20 KNOTS THROUGH THE WEEKEND. A WEAK TROUGH WILL
CROSS THE GREAT LAKES MONDAY...BUT AGAIN...WINDS WILL REMAIN LESS
THAN 20 KNOTS. HIGH PRESSURE WILL RESUME CONTROL OF THE WRN GREAT
LAKES TUESDAY THROUGH THE END OF THE WEEK TO KEEP WINDS GENERALLY
LIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KLUBER
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
501 AM EDT SAT AUG 10 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 500 AM EDT SAT AUG 10 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
QUEBEC RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. THE MOST
PROMINENT UPSTREAM SHORTWAVE TROUGH WAS LOCATED OVER SW SASK. AT THE
SFC...A WEAK TROUGH EXTENDED FROM JAMES BAY INTO NE LAKE SUPERIOR
WHILE A RIDGE EXTENDED FROM ND INTO MN AND IA. IR LOOP SHOWED MAINLY
CLEAR SKIES OVER UPPER MICHIGAN WHICH HAS ALLOWED TEMPS TO DROP INTO
THE LOWER TO MID 40S INLAND. THE NRN EDGE OF A MORE EXTENSIVE AREA OF
CLOUD HAS REMAINED TO THE WEST AND SOUTH FROM NEAR ASX TO MNM.
TODAY...WITH THE WEAK 850-700 MB THERMAL TROUGH REMAINING NEAR THE
AREA...EXPECT SCT/BKN CU TO AGAIN DEVELOP THIS AFTERNOON. EVEN WITH
PROMINENT LAKE BREEZE BOUNDARIES THIS AFTERNOON IN THE RELATIVELY
LIGHT WIND FIELD...A STRONG CAP/INVERSION AROUND 700 MB...PER MDLS
SOUNDINGS AND AREA 00Z RAOBS...AND DRY LOW LEVELS WILL INHIBIT ANY
PCPN. NO MORE THAN A BRIEF SPRINKLE WOULD BE EXPECTED OUT OF THE
RELATIVELY SHALLOW CONVECTIVE CLOUDS. TEMPS WILL CLIMB TO NEAR
NORMAL...IN THE LOWER TO MID 70S.
TONIGHT...THE SASK SHRTWV WILL APPROACH UPPER MI TONIGHT BUT ANY
PCPN WITH THIS FEATURE IS EXPECTED TO REMAIN TO THE W OF THE CWA.
THE SIGNFICANT PCPN WILL REMAIN WELL TO THE SOUTH...CLOSER TO THE
850 MB FRONT OVER SRN MN. INCREASING MID CLOUDS LATE WILL KEEP TEMPS
FROM FALLING OFF AS MUCH WITH MIN READINGS IN THE MID 40S TO LOWER
50S.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 358 AM EDT SAT AUG 10 2013
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED SUNDAY
AFTERNOON AND MONDAY BEFORE BROAD HIGH PRESSURE GAINS CONTROL OF THE
REGION AND BRINGS AN EXTENDED PERIOD OF DRY WEATHER THROUGH THE
UPCOMING WEEK. TEMPERATURES WILL CONTINUE TO BE SLIGHTLY BELOW
NORMAL...WITH A COUPLE CHILLY NIGHTS EXPECTED FOR THE FIRST PART OF
THE WEEK.
SUNDAY...A BROAD MID-LEVEL TROUGH CENTERED OVER FAR NORTHERN
ONTARIO WILL BE MAKING A SOUTHWARD PUSH AT THE START OF THE PERIOD.
MAIN FORECAST FOCUS CONTINUES TO BE ON THE POTENTIAL FOR AFTERNOON
SHOWERS AND THUNDER ACROSS INTERIOR PORTIONS OF THE CWA. MODEL
GUIDANCE HAS BEEN QUITE PERSISTENT FOR SEVERAL NIGHTS NOW WITH
ADVERTISING THE PASSAGE OF A LEAD SHORTWAVE ACROSS UPPER MI ON
SUNDAY AFTERNOON AND EVENING. THIS WAVE IS A RESULT OF PHASING
BETWEEN SMALL PIECES OF ENERGY FROM WESTERN CANADA AND THE LARGER
TROUGH. THE ECMWF AND GEM ARE THE QUICKEST...AND HAVE THE TROUGH
OUTRUNNING PEAK HEATING BY CLEARING THE EASTERN CWA BY MID
AFTERNOON. THE NAM/LOCAL WRF/GFS ARE SLOWER...AND BRING THE WAVE
ACROSS THE CENTRAL CWA AROUND EARLY AFTERNOON. SUBTLE NW FLOW
FEATURES CAN BE QUITE FICKLE THIS TIME OF YEAR...SO AM NOT TOO
CONFIDENT IN JUMPING ON EITHER SOLUTION ATTM. GIVEN COMPETING
DYNAMICS BETWEEN THE MID-LEVEL WAVE AND THE LEFT ENTRANCE OF AN 80
KT UPPER JET...WILL MAINTAIN THE FOCUS FOR PRECIP CHANCES ACROSS THE
SOUTH CENTRAL AND INTERIOR EAST WHERE ASSISTANCE FROM LAKE BREEZE
CONVERGENCE WILL BOOST DIURNAL ACTIVITY.
ONE CONCERN WITH THUNDER POTENTIAL OVER THE PAST COUPLES DAYS HAS
BEEN LOWER INSTABILITY DUE TO CLOUDS FROM CONVECTION TO THE SOUTH.
WITH MLCAPE PEAKING AT ONLY 500 J/KG FAR SOUTH CENTRAL...THUNDER
COVERAGE WILL BE LIMITED. A DRY SUBCLOUD LAYER COULD STILL RESULT IN
SOME GUSTY WINDS TO 35 MPH WITH ANY SHOWERS THOUGH AS DOWNDRAFT CAPE
WILL BE OVER 500 J/KG.
SUNDAY NIGHT AND MONDAY...ANY ACTIVITY SUNDAY AFTERNOON SHOULD
DIMINISH WITH THE PASSAGE OF THE WAVE AND LOSS OF DAYTIME HEATING. A
WEAK SFC TROUGH ASSOCIATED WITH THE MID-LEVEL TROUGH WILL STILL BE
DRIFTING ACROSS THE EASTERN CWA INTO THE OVERNIGHT HOURS...BUT DO
NOT EXPECT ANY LINGERING SHOWERS GIVEN WEAK LIFT AND DRIER AIR. THE
MAIN TROUGH IS THEN PROGGED TO CROSS THE CWA DURING THE DAY ON
MONDAY. MID-LEVEL Q-VECTOR CONVERGENCE WITH A DECENT UPPER-LEVEL
NEGATIVE PV ANOMALY WILL BRING MODEST LIFT ACROSS THE NORTHERN CWA
AND LAKE SUPERIOR MONDAY AFTERNOON. ONCE AGAIN...DAYTIME HEATING
WILL ASSIST WITH PRECIP COVERAGE IN THE AFTERNOON. DO NOT EXPECT ANY
MORE COVERAGE THAN SUNDAY AFTERNOON AS MID-LEVEL CAPPING BEHIND
SUNDAYS TROUGH WILL LIMIT VERTICAL GROWTH OF ANY SHOWERS. WILL
MAINTAIN GOING FORECAST WITH BEST CHANCE POPS AND SLIGHT CHANCE OF
THUNDER SOUTH-CENTRAL AND INTERIOR EAST IN THE AFTERNOON.
TUESDAY THROUGH FRIDAY...HIGH PRESSURE WILL BUILD INTO THE CWA FROM
THE WEST BEGINNING MONDAY NIGHT AND SETTLE OVER THE REGION TUESDAY
NIGHT. PWAT VALUES OF 0.5 INCHES OR LESS AND LIGHT WINDS WILL LEAD
TO GREAT RADIATIONAL COOLING BOTH MONDAY AND TUESDAY NIGHTS.
GUIDANCE THAT HAS VERIFIED THE BEST OVER RECENT COOL NIGHTS PRODUCES
MIN TEMPS WELL INTO THE 40S INLAND...ESPECIALLY TUESDAY NIGHT. COULD
EVEN SEE SOME UPPER 30S TUESDAY NIGHT AT THE TYPICAL COOL
SPOTS...BUT DID NOT GO THAT LOW QUITE YET GIVEN UNCERTAINTY IN THE
EXACT PLACEMENT OF THE SFC HIGH. OVERALL...LOWERED TEMPS BY A COUPLE
DEGREES FOR BOTH NIGHTS. ALSO ADDED SOME PATCHY FOG ACROSS THE
INTERIOR WEST HALF MONDAY NIGHT SINCE THEY WILL HAVE SEEN A FEW
SHOWERS ON MONDAY AFTERNOON AND CROSSOVER TEMPS SHOULD BE SURPASSED
BY SEVERAL DEGREES.
ANOTHER WEAK TROUGH AXIS FROM THE MAIN EASTERN CANADIAN TROUGH WILL
SKIRT NE LAKE SUPERIOR THURSDAY. WITH MOISTURE LACKING AND BEST
DYNAMICS WELL NORTHEAST...KEPT PRECIP OUT OF THE FORECAST. A
PACIFIC-BASED WAVE COULD BEGIN AFFECTING THE WEST BY LATE
FRIDAY...BUT MODEL CONSISTENCY HAS BEEN POOR SO CONFIDENCE IS LOW IN
ANY PRECIP LATE IN THE WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 131 AM EDT SAT AUG 10 2013
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES THIS FORECAST
PERIOD. KSAW WILL SEE A NE LAKE BREEZE SAT AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 500 AM EDT SAT AUG 10 2013
HIGH PRESSURE MOVING INTO THE WRN GREAT LAKES WILL BRING RELATIVELY
LIGHT WINDS BELOW 20 KNOTS THROUGH THE WEEKEND. A WEAK TROUGH WILL
CROSS THE GREAT LAKES MONDAY...BUT AGAIN...WINDS WILL REMAIN LESS
THAN 20 KNOTS. HIGH PRESSURE WILL RESUME CONTROL OF THE WRN GREAT
LAKES TUESDAY THROUGH THE END OF THE WEEK TO KEEP WINDS GENERALLY
LIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KLUBER
AVIATION...07
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1003 PM CDT Sun Aug 11 2013
.UPDATE:
Issued at 958 PM CDT Sun Aug 11 2013
No significant changes made. Adjusted cloud cover upwards based on
thicker mid/high level deck advancing from KS and wrn MO.
Otherwise just minor adjustments to capture short term trends.
Overnight lows still look on track.
2%
&&
.SHORT TERM: (Through Late Tonight)
Issued at 313 PM CDT Sun Aug 11 2013
Low level flow is turning back around to the south across southern
and central Missouri. Already seeing cumulus spread up to near
California Missouri and points west-northwest. A weak low level jet
develops tonight which produces some decent moisture convergence at
850mb primarily over southern portions of the CWFA. It doesn`t look
like the forcing is strong enough to produce very widespread or
organized convection, however the RUC is showing about 900 J/KG CAPE
in the region of moisture convergence, and the CAPE is fairly tall
extending up to 35,000ft. Certainly can`t rule out isolated-widely
scattered showers and thunderstorms over southeast Missouri and
possibly parts of east central and central Missouri as well, though
the lift drops off further north. Lows will be warmer tonight due
to the increasing cloud cover and southerly flow.
Carney
.LONG TERM: (Monday through Next Sunday)
Issued at 313 PM CDT Sun Aug 11 2013
Main concern continues to be thunderstorms chances early this week.
Scattered thunderstorms may be ongoing over the eastern Ozarks into
southern Illinois early Monday on the nose of a veering low level
jet. Better chance of storms will be focused along a cold front
that enters the northern CWFA early in the day and moves slowly
south through the day. Atmosphere will become increasingly
unstable along and ahead of the front with MLCAPEs around 1,000
J/kg with some weak CIN. This should be enough to generate
scattered thunderstorms given weak large scale ascent from a
passing shortwave. There may be a few strong storms that could
producing some gusty winds given the relatively dry low-mid levels
seen on the forecast soundings, though deep layer shear of only
25-30 knots will limit overall severe threat.
Not too many changes to previous thinking that rain chances will
diminish from north to south on Monday Night and Tuesday as the
front slowly moves south into the Mid South. Still have a dry
forecast going mid to late week as an impressive surface ridge
creeps southward through the area. Easterly low level flow and
850mb temperatures around 10C should keep temperatures below mid
August normals from Wednesday into Friday. Latest runs of the
GFS/ECMWF do agree that an upper trough will deepen over Missouri
and Illinois by Saturday. There will be Gulf moisture drawn
northward ahead of this trough, though any rain looks like it will
stay just south and east of us next weekend. 850mb temperatures
will warm into the mid-teens causing temperatures to climb closer
to normal by next weekend.
Britt
&&
.AVIATION: (For the 00z TAFs through 00z Monday Evening)
Issued at 538 PM CDT Sun Aug 11 2013
Low-mid level cloudiness will likely spread nwd into the taf
sites late tonight as moisture spreads nwd. Could not rule out
isolated convection towards morning in COU and the St Louis
metro area...but the better chance should occur Monday afternoon
with the approach of an upper level disturbance from the west and
a cold front from the north. There should be at least scattered
showers and thunderstorms Monday afternoon and will include either
vcts or prob30 in the tafs for shra/tsra. Mainly a light sely sfc
wind tonight...then the wind will veer around to a wly direction
by Monday afternoon after fropa.
Specifics for KSTL: Little cloud cover this evening...then
increasing low-mid level cloudiness late tonight into Monday. There
could be a few showers or thunderstorms already towards morning
...but will leave the taf forecast dry until Monday afternoon. Light
sely sfc wind will increase to 7-8 kts on Monday and veer around
to a wly direction Monday afternoon.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
605 PM CDT Sun Aug 11 2013
.SHORT TERM: (Through Late Tonight)
Issued at 313 PM CDT Sun Aug 11 2013
Low level flow is turning back around to the south across southern
and central Missouri. Already seeing cumulus spread up to near
California Missouri and points west-northwest. A weak low level jet
develops tonight which produces some decent moisture convergence at
850mb primarily over southern portions of the CWFA. It doesn`t look
like the forcing is strong enough to produce very widespread or
organized convection, however the RUC is showing about 900 J/KG CAPE
in the region of moisture convergence, and the CAPE is fairly tall
extending up to 35,000ft. Certainly can`t rule out isolated-widely
scattered showers and thunderstorms over southeast Missouri and
possibly parts of east central and central Missouri as well, though
the lift drops off further north. Lows will be warmer tonight due
to the increasing cloud cover and southerly flow.
Carney
.LONG TERM: (Monday through Next Sunday)
Issued at 313 PM CDT Sun Aug 11 2013
Main concern continues to be thunderstorms chances early this week.
Scattered thunderstorms may be ongoing over the eastern Ozarks into
southern Illinois early Monday on the nose of a veering low level
jet. Better chance of storms will be focused along a cold front
that enters the northern CWFA early in the day and moves slowly
south through the day. Atmosphere will become increasingly
unstable along and ahead of the front with MLCAPEs around 1,000
J/kg with some weak CIN. This should be enough to generate
scattered thunderstorms given weak large scale ascent from a
passing shortwave. There may be a few strong storms that could
producing some gusty winds given the relatively dry low-mid levels
seen on the forecast soundings, though deep layer shear of only
25-30 knots will limit overall severe threat.
Not too many changes to previous thinking that rain chances will
diminish from north to south on Monday Night and Tuesday as the
front slowly moves south into the Mid South. Still have a dry
forecast going mid to late week as an impressive surface ridge
creeps southward through the area. Easterly low level flow and
850mb temperatures around 10C should keep temperatures below mid
August normals from Wednesday into Friday. Latest runs of the
GFS/ECMWF do agree that an upper trough will deepen over Missouri
and Illinois by Saturday. There will be Gulf moisture drawn
northward ahead of this trough, though any rain looks like it will
stay just south and east of us next weekend. 850mb temperatures
will warm into the mid-teens causing temperatures to climb closer
to normal by next weekend.
Britt
&&
.AVIATION: (For the 00z TAFs through 00z Monday Evening)
Issued at 538 PM CDT Sun Aug 11 2013
Low-mid level cloudiness will likely spread nwd into the taf
sites late tonight as moisture spreads nwd. Could not rule out
isolated convection towards morning in COU and the St Louis
metro area...but the better chance should occur Monday afternoon
with the approach of an upper level disturbance from the west and
a cold front from the north. There should be at least scattered
showers and thunderstorms Monday afternoon and will include either
vcts or prob30 in the tafs for shra/tsra. Mainly a light sely sfc
wind tonight...then the wind will veer around to a wly direction
by Monday afternoon after fropa.
Specifics for KSTL: Little cloud cover this evening...then
inceasing low-mid level cloudiness late tonight into Monday. There
could be a few showers or thunderstorms already towards morning
...but will leave the taf forecast dry until Monday afternoon. Light
sely sfc wind will increase to 7-8 kts on Monday and veer around
to a wly direction Monday afternoon.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1242 PM CDT Sat Aug 10 2013
.UPDATE:
Issued at 1224 PM CDT Sat Aug 10 2013
A band of strato-cu has developed stretching from near Vichy Missouri to
just south of Taylorville Illinois. Some of the clouds look to
have some decent vertical development so would not be surprised to
see some showers pop out. Have updated the forecast to account for
this. Elsewhere and otherwise the forecast looks good for the rest
of the afternoon.
Carney
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 317 AM CDT Sat Aug 10 2013
Early morning precipitation over eastern OK and southern MO was
being handled fairly well by the RAP. Based on RAP forecasts of H85
moisture convergence, SHRA/TSRA over southern MO/IL should begin to
taper off after 15Z. Heavy downpours are still possible this morning
since PW values remain near 2 inches. With a surface high pressure
center building into the region and a drier air mass spreading
southward today, any afternoon convection should be confined to
areas closer to the active quasistationary front near the MO/AR
border.
Kanofsky
.LONG TERM: (Tonight through Friday)
Issued at 317 AM CDT Sat Aug 10 2013
All of the 00z NWP output is much more aggressive with the southward
surge of the surface ridge into the mid Mississippi Valley tonight
and into Sunday. Not only will this mean lower dewpoints and
slightly cooler temps, but this will also give the stubborn
baroclinic zone that has been anchored over southern Missouri and
northern Arkansas a gentle but significant southward nudge. This
will greatly lessen the threat of convection that has seemingly
been a nightly occurrence for almost a week over southern Missouri.
I have held onto some low pops in our southern counties both tonight
and Sunday just in case the later solutions back off on the
southward push of the ridge, but if 00z guidance verifies with its
trends any rainfall tonight and Sunday should primarily fall south
of our CWA.
Surface ridge still expected to retreat Sunday night into Monday,
allowing the resultant return flow to cause a northward return of
the warm and moist air. Have continued slight chance pops for most
areas on Sunday night, but it would appear better threat for
convection will hold off until Monday when shortwave energy will be
able to interact with a diurnal increase of instability. This
threat should continue into Monday night. These thunderstorm
chances should shut down with the arrival of the next front...which
the 00z guidance suggests will be about 12 hours slower that earlier
solutions. POPS should diminish from north to south Monday night and
Tuesday.
Consensus of tonight`s medium range guidance dovetails with that of
yesterday`s day shift, and indicates a fairly significant deepening
of the upper trof that is progged to form over the Great Lakes and
eastern U.S during the latter half of next week. This in turn means
stronger high pressure and a bit more of the associated Canadian
airmass backdooring into region. Going trends for the
Wednesday-Friday frame still look very good, with this early surge
of Canadian air providing the region with unseasonably low
humidities and cooler than average temperatures for mid August, and
little if any threat of rain.
Truett
&&
.AVIATION: (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1224 PM CDT Sat Aug 10 2013
Expect VFR flight conditions and light northerly flow for the rest
of the day. There is a band of strato-cu stretching from near KVIH
to KMTO across the area. Wouldn`t be surprised to see some showers
pop out of these clouds a little later in the day. Also...some
scattered thunderstorms remain possible over parts of the eastern
Ozarks through early evening. Tonight...river valley fog is
possible...tho the chance may be diminished by drier air moving in
from the north.
Specifics for KSTL:
Expect VFR flight conditions and light northerly flow through
Sunday. There is a band of strato-cu stretching from near KVIH
to KMTO across the area. Wouldn`t be surprised to see some showers
pop out of these clouds a little later in the day...but it looks
like any rain should stay south of the terminal.
Carney
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
635 AM CDT Sat Aug 10 2013
.SHORT TERM: (Through Late This Afternoon)
Issued at 317 AM CDT Sat Aug 10 2013
Early morning precipitation over eastern OK and southern MO was
being handled fairly well by the RAP. Based on RAP forecasts of H85
moisture convergence, SHRA/TSRA over southern MO/IL should begin to
taper off after 15Z. Heavy downpours are still possible this morning
since PW values remain near 2 inches. With a surface high pressure
center building into the region and a drier air mass spreading
southward today, any afternoon convection should be confined to
areas closer to the active quasistationary front near the MO/AR
border.
Kanofsky
.LONG TERM: (Tonight through Friday)
Issued at 317 AM CDT Sat Aug 10 2013
All of the 00z NWP output is much more aggressive with the southward
surge of the surface ridge into the mid Mississippi Valley tonight
and into Sunday. Not only will this mean lower dewpoints and
slightly cooler temps, but this will also give the stubborn
baroclinic zone that has been anchored over southern Missouri and
northern Arkansas a gentle but significant southward nudge. This
will greatly lessen the threat of convection that has seemingly
been a nightly occurrence for almost a week over southern Missouri.
I have held onto some low pops in our southern counties both tonight
and Sunday just in case the later solutions back off on the
southward push of the ridge, but if 00z guidance verifies with its
trends any rainfall tonight and Sunday should primarily fall south
of our CWA.
Surface ridge still expected to retreat Sunday night into Monday,
allowing the resultant return flow to cause a northward return of
the warm and moist air. Have continued slight chance pops for most
areas on Sunday night, but it would appear better threat for
convection will hold off until Monday when shortwave energy will be
able to interact with a diurnal increase of instability. This
threat should continue into Monday night. These thunderstorm
chances should shut down with the arrival of the next front...which
the 00z guidance suggests will be about 12 hours slower that earlier
solutions. POPS should diminish from north to south Monday night and
Tuesday.
Consensus of tonight`s medium range guidance dovetails with that of
yesterday`s day shift, and indicates a fairly significant deepening
of the upper trof that is progged to form over the Great Lakes and
eastern U.S during the latter half of next week. This in turn means
stronger high pressure and a bit more of the associated Canadian
airmass backdooring into region. Going trends for the
Wednesday-Friday frame still look very good, with this early surge
of Canadian air providing the region with unseasonably low
humidities and cooler than average temperatures for mid August, and
little if any threat of rain.
Truett
&&
.AVIATION: (For the 12z TAFs through 12z Sunday Morning)
Issued at 620 AM CDT Sat Aug 10 2013
Patchy light fog will quickly dissipate this morning, leaving VFR
conditions for the rest of the TAF period. Precipitation should
remain well to the south of the terminals since the active frontal
boundary is near the MO/AR border.
Specifics for KSTL: VFR through the period with light northerly
winds.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
318 AM CDT Sat Aug 10 2013
.SHORT TERM: (Through Late This Afternoon)
Issued at 317 AM CDT Sat Aug 10 2013
Early morning precipitation over eastern OK and southern MO was
being handled fairly well by the RAP. Based on RAP forecasts of H85
moisture convergence, SHRA/TSRA over southern MO/IL should begin to
taper off after 15Z. Heavy downpours are still possible this morning
since PW values remain near 2 inches. With a surface high pressure
center building into the region and a drier air mass spreading
southward today, any afternoon convection should be confined to
areas closer to the active quasistationary front near the MO/AR
border.
Kanofsky
.LONG TERM: (Tonight through Friday)
Issued at 317 AM CDT Sat Aug 10 2013
All of the 00z NWP output is much more aggressive with the southward
surge of the surface ridge into the mid Mississippi Valley tonight
and into Sunday. Not only will this mean lower dewpoints and
slightly cooler temps, but this will also give the stubborn
baroclinic zone that has been anchored over southern Missouri and
northern Arkansas a gentle but significant southward nudge. This
will greatly lessenthe threat of convection that has seeminly
been a nightly occurrance for almost a week over southern Missouri.
I have held onto some low pops in our southern counties both tonight
and Sunday just in case the later solutions back off on the
southward push of the ridge, but if 00z guidance verifies with its
trends any rainfall tonight and Sunday should primarily fall south
of our CWA.
Surface ridge still expected to retreat Sunday night into Monday,
allowing the resultant return flow to cause a northward return of
the warm and moist air. Have continued slight chance pops for most
areas on Sunday night, but it would appear better threat for
convection will hold off until Monday when shortwave energy will be
able to interact with a diurnal increase of instability. This
threat should continue into Monday night. These thunderstorm
chances should shut down with the arrival of the next front...which
the 00z guidance suggests will be about 12 hours slower that earlier
solutions. POPS should diminish from north to south Monday night and
Tuesday.
Consensus of tonight`s medium range guidance dovetails with that of
yesterday`s day shift, and indicates a fairly significant deepening
of the upper trof that is progged to form over the Great Lakes and
eastern U.S during the latter half of next week. This in turn means
stronger high pressure and a bit more of the associated Canadian
airmass backdooring into region. Going trends for the
Wednesday-Friday frame still look very good, with this early surge
of Canadian air providing the region with unseasonably low
humidities and cooler than average temperatures for mid August, and
little if any threat of rain.
Truett
&&
.AVIATION: (For the 06z TAFs through 06z Saturday Night)
Issued at 1050 PM CDT Fri Aug 9 2013
The focus for most of the convection late tonight and Saturday
should continue to be south of the taf sites. Much of the low-mid
level cloudiness may advect east-southeast of COU and UIN late
tonight and east-southeast of the St Louis metro area Saturday
morning. Patchy fog will develop late tonight/early Saturday
morning due to the light sfc winds...and especially in areas where
the clouds clear out. N-nely sfc wind will increase to around 7-8
kts by late Saturday morning and afternoon...then become light
again Saturday evening.
Specifics for KSTL: VFR low-mid level clouds will continue late
tonight...then advect east-southeast of STL Saturday morning. The
light sfc wind will increase to around 8 kts Saturday afternoon
from a nly direction...then diminish again Saturday night.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1111 PM CDT Fri Aug 9 2013
.UPDATE:
Issued at 935 PM CDT Fri Aug 9 2013
The highly unusual August pattern continues.
A weak cold front has since pushed further into central IL and
about halfway between KUIN and KSTL in MO. As a result, the old
line of SHRA/TSRA has dissipated, but it has helped to give more
form to the sprinkles that have been moving through the area, and
has resulted in isolated SHRA in parts of SW IL. This feature is
essentially going to merge with the upper level disturbance now
moving through east- central MO, where the SHRA there has all but
faded after sunset. Look for a continued low threat for SHRA into
the overnight between this upper level disturbance moving through
and the weak cold front that will primarily be focused on the IL
side of the MS river.
If clouds exit faster than anticipated, the low temp-dewpoint
spreads may result in another night of patchy fog. Current
indications are they will linger for much of the night, though.
Just south of the forecast area, an old frontal boundary exists
and has been the main focus for waves of rain for the past several
nights on the cool side. The next 24 hours will probably not be
much different, with another wave of SHRA/TSRA expected to move
into SE MO Saturday morning, the difference expected to be the
trend for rain further and further south with each day.
Temps look to be in the ballpark for mins in the 60s.
TES
&&
.SHORT TERM: (Through Late Tonight)
Issued at 317 PM CDT Fri Aug 9 2013
Area of rain extending from central Missouri into southwest Illinois
has persisted on the north side of a side of MCV that is currently
tracking through southeast Missouri. This rain will continue to
show a slow decrease in areal coverage and intensity as the vort
moves off to the east. Focus for additional showers and
thunderstorms this evening will then shift closer to a front over
southern Missouri into southern Illinois. RAP and Local WRF shows
low level forcing persisting along and north of this front most of
the night, so will keep chances of showers and thunderstorms mainly
in areas along and south of I-44 in Missouri and I-64 in
Illinois.
Britt
.LONG TERM: (Saturday through Next Friday)
Issued at 317 PM CDT Fri Aug 9 2013
Primary concern for Saturday through early next week continues to be
timing and intensity of precipitation as quasi-zonal/northwest flow
pattern continues to control our weather. Am continuing the
persistence forecast with high chance/likely pops across the eastern
Ozarks and extreme southwest Illinois, fading to low chance/slight
chance up along the I-70 corridor for Saturday. This morning`s
850mb analysis showed a strong dewpoint gradient along the I-70 with
northerly flow across northern Missouri and moist west-southwest
flow to the south of the gradient. This gradient along with the
northerly flow feeding it is probably at least partially responsible
for the lack of northward progress for today`s precipitation. All
short range guidance keeps the 850mb dewpoint gradient in basically
the same place, hence the persistence forecast. The gradient washes
out on Sunday allowing deeper moisture to filter back into the
region. However, there appears to be a general lack of dynamic
forcing on Sunday with just some weak isentropic lift on 10kt low
level southwest flow. With nothing obvious to focus convection,
will spread chance pops further north, but am not particularly
excited about going with pops higher than chance anywhere at this
time. On Monday, a strong shortwave is forecast to drop down into
the Great Lakes region which should amplify the eastern trof and
push a cold front into the mid Mississippi Valley with a
corresponding increase in pops across the area.
Medium range guidance shows a sprawling high pressure system
building down across the Upper Midwest into the Great Lakes region
late Tuesday into Wednesday. This airmass will be cooler and much
drier than is normal for mid August. 850mb temps on the GFS are
progged to be around 10-12C...which would mix down to the low to mid
70s. The ECMWF is somewhat warmer at 12-14C. Given the
discrepancy...have opted to to stick with ensemble guidance with
highs in the upper 70s to low 80s and lows in the upper 50s to low
to 60s.
Carney
&&
.AVIATION: (For the 06z TAFs through 06z Saturday Night)
Issued at 1050 PM CDT Fri Aug 9 2013
The focus for most of the convection late tonight and Saturday
should continue to be south of the taf sites. Much of the low-mid
level cloudiness may advect east-southeast of COU and UIN late
tonight and east-southeast of the St Louis metro area Saturday
morning. Patchy fog will develop late tonight/early Saturday
morning due to the light sfc winds...and especially in areas where
the clouds clear out. N-nely sfc wind will increase to around 7-8
kts by late Saturday morning and afternoon...then become light
again Saturday evening.
Specifics for KSTL: VFR low-mid level clouds will continue late
tonight...then advect east-southeast of STL Saturday morning. The
light sfc wind will increase to around 8 kts Saturday afternoon
from a nly direction...then diminish again Saturday night.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
900 PM MDT SUN AUG 11 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH TUESDAY...
SENT AN UPDATE TONIGHT CONSIDERING THE LATEST MODEL OUTPUTS
REGARDING THE EXTENT OR RAIN SHOWER AND THUNDERSTORM COVERAGE FROM
CENTRAL MONTANA MAKING ITS WAY EASTWARD OVER OUR CWA. ALTHOUGH THE
00Z UPDATE FROM THE NAM SHOWS MOSTLY DRY...THE HRRR KEEPS UPDATING
HOURLY WITH MORE ACTIVITY INCLUDING A LINEAR SCATTERED BAND OF
SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS NNW TO SSE FROM THE
PORT OF MORGAN THROUGH JORDAN LATER TONIGHT. TOOK A RISK AND
LEANED MORE TOWARD THE HRRR MODEL FOR THE UPDATE. BMICKELSON
PREVIOUS SHORT TERM DISCUSSION...THIS EVENING INTO TONIGHT WILL
BRING A COUPLE OF FORECAST CHALLENGES TO THE AREA. FIRST WILL BE
DETERMINING HOW FAR EAST THE SHOWER AND THUNDERSTORM ACTIVITY
CURRENTLY DEVELOPING ACROSS CENTRAL MONTANA WILL PROGRESS. WHILE
THERE ARE MODEL DIFFERENCES IN PLACEMENT OF QPF...BEST CONSENSUS
APPEARS TO BE IN THE SOUTHERN AND WESTERN ZONES AND THIS HAS
ADDITIONAL SUPPORT FROM THE LATEST HRRR. VISIBLE SATELLITE IMAGERY
AND RADAR TRENDS SHOW POSSIBLE SHOWERS DEVELOPING TO THE WEST OF
PHILLIPS AND PETROLEUM COUNTY. ADDITIONAL SHOWERS/THUNDERSTORMS
EXIST ACROSS SOUTHERN ALBERTA/SASKATCHEWAN. THEREFORE WILL LEAVE
SLIGHT CHANCE/CHANCE POPS IN THE GRIDS FOR THIS EVENING IN THOSE
AREAS. DECIDED TO USE UNCERTAINTY WORDING INSTEAD OF COVERAGE DUE
TO LACK OF CONFIDENCE FOR THIS EVENING. CONVECTION MAY WANE
TOWARD/AFTER SUNSET AS THE NOCTURNAL BOUNDARY LAYER BECOMES
SOMEWHAT MORE STABLE. THE OTHER CHALLENGE FOR TONIGHT WILL BE
MINIMUM TEMPERATURES. GIVEN THAT THE NORTHEAST WAS SOMEWHAT COOLER
THAN EXPECTED THE LAST COUPLE OF NIGHTS...TRENDED THE LOWS DOWN A
BIT FOR TONIGHT. OPHEIM TO PLENTYWOOD IN PARTICULAR MAY BE COOL IN
ADDITION TO SOME OF THE DEEPER VALLEY LOCATIONS. THERE WILL ALSO
BE MORE IN THE WAY OF CLEAR SKIES IN THOSE AREAS ASSISTING IN
RADIATIONAL COOLING.
MONDAY AND TUESDAY...OVERALL SYNOPTIC PATTERN REMAINS FAIRLY
STATIC WITH LARGE UPPER RIDGE TO THE WEST DRIVING NORTHWEST FLOW
ALOFT THROUGH THE CWA. INSTABILITY LOOKS TO INCREASE FOR
ESPECIALLY SOUTHWESTERN ZONES EARLY NEXT WEEK. FORECAST SOUNDINGS
INDICATE CONVECTIVE PARAMETERS FAVORABLE FOR SMALL HAIL AND MAYBE
SOME GUSTY WINDS. RECENT STORMS HAVE ALSO BEEN HEAVY RAIN
PRODUCERS OVER THE LAST COUPLE OF DAYS AND WITH LITTLE CHANGE TO
THE OVERALL FORCING GOING INTO THESE STORMS...WILL NEED TO
EVALUATE HEAVY RAIN POTENTIAL WITH STORMS AS WELL. AN ISOLATED
STORM MAY BECOME SEVERE ON MONDAY OR TUESDAY BUT CONFIDENCE IS LOW
AND SO WILL NOT INTRODUCE WORDING INTO THE GRIDS. CURRENTLY LEANED
HEAVILY ON THE 12Z/11 ECMWF/SREF SOLUTIONS FOR THE PERIOD AS THEY
SEEM TO HANDLE THIS WELL AND HAVE PERFORMED RECENTLY COMPARED WITH
OTHER MODELS. NAM ALSO SHOWS SUPPORT BUT HAS SLIGHT
TIMING/PLACEMENT DIFFERENCES. GFS IS IN AGREEMENT FOR MONDAY BUT
HAS A DRIER OUTPUT FOR THE CWA ON TUESDAY AFTERNOON. SINCE THIS IS
AN OUTLIER...WILL NOT GIVE IT TOO MUCH REGARD FOR THIS FORECAST
CYCLE. FOR TEMPERATURES...MAINTAINED GRADUAL WARMING WITH LARGE
UPPER LEVEL RIDGE BUILDING IN THROUGH THE EARLY PART OF NEXT WEEK
ALLOWING FOR RISING 500MB HEIGHTS. MODEL GUIDANCE ALSO CONTINUES
TO SHOW A GRADUALLY WARMING 850MB TEMPERATURE PATTERN. MALIAWCO
.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...
MID-SUMMER PATTERN SETTING UP FOR THIS PERIOD. TEMPS SHOULD GET TO
NORMAL OR SLIGHTLY ABOVE NORMAL LEVELS ESPECIALLY SATURDAY. BEST CHANCE
OF STORMS LOOK TO BE ABOUT WEDNESDAY BUT MODELS ARE SHOWING SOME
CAPPING TOO. GOING FORECAST HAS THIS HANDLED WELL AND MADE NO
UPDATES. TFJ
PREVIOUS DISCUSSION...
UPPER RIDGE GRADUALLY BUILDS INTO MONTANA DURING THE EXTENDED
PERIOD.
FROM TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...THERE WILL BE A SLOW
MOVING WARM FRONT ACROSS THE REGION WHICH WILL BE THE FOCUS FOR
SHOWERS AND THUNDERSTORMS AT TIMES. THE STORMS WILL BE PARTLY
DRIVEN BY DAYTIME INSTABILITY AND PARTLY DRIVEN BY SHORTWAVES THAT
OVERTOP THE RIDGE AXIS. MODELS TIME THE WAVES DIFFERENTLY WHICH
RESULTS IN MODELS TIMING THE STORMS DIFFERENTLY. AT THIS POINT...
IT LOOKS LIKE THE BEST CHANCE FOR STORMS WILL BE WEDNESDAY
AFTERNOON AND EVENING WHEN THE WARM FRONT IS OVER EASTERN MONTANA.
IT MAY BE UNSTABLE ENOUGH FOR SEVERE STORMS ON WEDNESDAY. THE
CHANCES OF SHOWERS AND THUNDERSTORMS COULD LINGER INTO THURSDAY IN
THE EAST DEPENDING ON HOW FAST THE FRONT MOVES EAST.
FOR FRIDAY AND SATURDAY...THE UPPER RIDGE TAKES CONTROL OF THE
WEATHER WITH TEMPERATURES NEAR 90 POSSIBLY WARMER WITH LITTLE OR
NO CHANCE OF PRECIPITATION.
SATURDAY NIGHT AND SUNDAY...THE RIDGE MOVES TO THE EAST AND
SOUTHWEST FLOW ALOFT MOVES INTO THE AREA. SHORTWAVES IN THE
SOUTHWEST FLOW WILL COMBINE WITH A COLD FRONT FOR A SLIGHT CHANCE
OF THUNDERSTORMS. FORRESTER
&&
.AVIATION...
VFR. SCATTERED CLOUDS ABOVE 12K AGL INTO MONDAY WITH EAST WINDS
CONTINUING AT 5 TO 15 KTS...STRONGEST AT KGGW. KGDV COULD SEE AN
ISOLATED THUNDERSTORM OVERNIGHT...WITH CONDITIONS BRIEFLY LOWERED
TO MVFR. TFJ/GILCHRIST
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BILLINGS MT
849 PM MDT SUN AUG 11 2013
.UPDATE...
WITH THE EXCEPTION OF A LONE STRONG STORM NEAR TONGUE RIVER
RESERVOIR...THUNDERSTORM ACTIVITY HAS QUIETED DOWN SIGNIFICANTLY
AS OF 830 PM. OVERALL...STORMS HAVE BEEN LESS INTENSE THAN THEY
WERE ON SATURDAY...LIKELY DUE TO WEAKER FORCING AND A STRONGER
PUSH OF DRY AIR FROM THE GREAT BASIN HAVING AN IMPACT ON THE
CONVECTION WHICH INITIATED OVER OUR SW MTNS DURING THE AFTERNOON.
THAT BEING SAID...THE SE BIG HORN COUNTY STORM IS MOVING INTO A
MORE FAVORABLE AIRMASS WITH GREATER SHEAR AND INSTABILITY WITH A
SELY LOW LEVEL JET IN OUR EAST...SO IT MAY SUSTAIN ITSELF FOR A
LITTLE WHILE. HRRR HAS BEEN CONSISTENTLY SHOWING A BAND OF
ACTIVITY LATER THIS EVENING INTO THE OVERNIGHT HOURS ACROSS OUR
NORTH CENTRAL TO EASTERN PARTS...PER MID LEVEL SHORTWAVE IN
CENTRAL MT AND AFOREMENTIONED LLJ...SO WILL KEEP ISOLATED POPS
GOING THROUGH 12Z IN OUR EAST HALF. FOR THE EVENING HOURS...HAVE
ADJUSTED POPS DOWN GIVEN EVENING TRENDS. FINALLY...CANNOT RULE OUT
FOG AGAIN ACROSS OUR EAST AS EAST WINDS WILL PERSIST...AND CURRENT
DEWPTS REMAIN QUITE HIGH IN THE UPPER 50S. JKL
&&
.SHORT TERM...VALID FOR MON AND TUE...
TODAY IS PLAYING OUT VERY SIMILAR TO YESTERDAY OVER CENTRAL AND
EASTERN ZONES...ONLY WITH LESS POTENTIAL FOR SEVERE STORMS OVER
EASTERN ZONE AS THERE IS NOT THE STRONG SHORTWAVE THERE WAS
YESTERDAY. OVERALL EXPECT THE NEXT COUPLE OF DAYS TO BE VERY
SIMILAR TO THE PAST COUPLE...WITH SLIGHTLY WARMER AND DRIER AIR
TRYING TO WORK INTO THE REGION FROM THE WEST BUT HAVING A TOUGH
TIME. THE REASON MOISTURE IS HANGING AROUND IS DUE TO THE SURFACE
HIGH TO THE NORTHEAST OF THE AREA AND THERMAL TROF TO THE WEST.
EACH NIGHT DRIER DENSER AIR IS WORKING FURTHER NORTH AND EAST OFF
THE MOUNTAINS...IT EVEN MADE IT TO BILLINGS THIS MORNING...BUT IN
THE AFTERNOON THE NORTHEASTERLY PRESSURE GRADIENT ACCELERATES
NORTHEASTERLY WINDS THAT PUSH VERY MOIST LOW LEVEL AIR BACK TO THE
DIVIDE. IN THE AFTERNOON WE ARE GETTING VERY WEAK WAVES OF ENERGY
PUSHING SLOWLY NORTHWARD UNDER THE WEAK RIDGE JUST TO THE WEST OF
THE AREA GENERATING THUNDERSTORMS FROM THE LOW LEVEL MOISTURE.
THIS PATTERN LOOKS TO CONTINUE THROUGH AT LEAST WEDNESDAY...SO
EXPECT TEMPERATURES IN THE 80S ACROSS THE AREA WITH LOWS IN THE
50S AND ABOUT A 30 PERCENT CHANCE OF THUNDERSTORMS EACH AFTERNOON
AND EVENING. STORMS MAY LINGER ACROSS NORTHERN AND EASTERN ZONES
INTO THE LATE NIGHT HOURS EACH NIGHT AS THE WEAK UPPER ENERGY
PIVOTS EASTWARD ON THE EAST SIDE OF THE RIDGE AXIS. THREAT FOR
SEVERE STORMS LOOKS VERY MARGINAL AS SHEAR VALUES ARE UNDER 10 KTS WEST
AND CENTRAL...AND 20 TO MAYBE 30 KTS EAST. THERE IS PLENTY OF
CAPE AVAILABLE FOR STORMS THOUGH AND CELL MERGERS AND CONVERGING
OUTFLOW BOUNDARIES MAY BE CAPABLE OF PRODUCING STRONG ENOUGH LIFT
FOR MARGINAL SEVERE HAIL. HEAVY RAIN WILL BE POSSIBLE CENTRAL AND
EAST WITH SLOW MOVING STORMS AND THE AFOREMENTIONED MOISTURE
AVAILABILITY. WESTERN AREAS COULD SEE A FEW STRONG WIND GUSTS OVER
50 MPH AS TEMP/DEWPOINT SPREADS THERE WILL BE OVER 40 DEGREES.
CHAMBERS
.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...
THE EXTENDED FORECAST APPEARS IN GOOD SHAPE...SO MADE ONLY A FEW
VERY MINOR TWEAKS TO THE INHERITED FORECAST. THE HIGH PRESSURE
RIDGE THE HAS BEEN IN PLACE ACROSS THE WEST...AND KEEPING
UNSETTLED WEATHER ACROSS THE CWA WILL SLIP EASTWARD MIDWEEK AND
DOMINATE THE BULK OF THE EXTENDED PERIOD.
THE UNSETTLED WEATHER PATTERN WILL WIND UP WEDNESDAY AND WEDNESDAY
NIGHT...WITH A STRONGER WAVE PROGGED TO CRASH THROUGH THE RIDGE.
THE RIDGE WILL REDEVELOP THURSDAY AN SHIFT EASTWARD. THIS SHOULD
END THE UNSETTLED WEATHER ACROSS THE AREA...WITH THE RIDGE SLOWLY
SLIPPING EASTWARD AND DOMINATING THE UPPER LEVEL WEATHER PATTERN
INTO THE WEEKEND. MODELS DIVERGE TO END THE PERIOD SATURDAY AND
SUNDAY...WITH A WAVE OF VARIABLE STRENGTH KICKING ACROSS THE
REGION. HAVE CONTINUES WITH SLIGHT CHANCE FOR THIS TIME
FRAME...BUT SYSTEM WILL REQUIRE FURTHER ATTENTION IN THE
FUTURE...BOTH FOR WEATHER DEVELOPMENT...AND FIRE WEATHER
CONCERNS. AAG
&&
.AVIATION...
AN ISOLATED THUNDERSTORM WITH AN MVFR TO IFR CONDITION WILL BE
POSSIBLE FOR ALL LOCATIONS THROUGH 06Z THEN MAINLY NEAR THE
WYOMING AND DAKOTA BORDERS AFTER 06Z. HEAVY RAIN WILL BE LIKELY
WITH ANY THUNDERSTORM. OTHERWISE...VFR CONDITIONS WILL PREVAIL
THROUGHOUT THE EVENING AND OVERNIGHT HOURS. HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
MON TUE WED THU FRI SAT SUN
-----------------------------------------------------------
BIL 060/087 059/085 059/087 060/091 062/093 062/091 058/085
23/T 33/T 32/T 20/U 00/U 01/U 21/U
LVM 052/086 052/085 052/088 050/091 051/095 051/090 051/084
22/T 33/T 32/T 21/U 10/U 01/U 21/U
HDN 058/088 058/086 057/088 059/092 059/095 059/093 059/088
23/T 33/T 32/T 20/U 00/U 00/U 21/U
MLS 061/087 060/085 059/087 061/091 063/094 064/093 063/089
23/T 33/T 23/T 31/U 00/U 01/U 22/T
4BQ 058/086 057/083 056/087 058/090 059/093 059/093 060/088
23/T 33/T 33/T 30/U 00/U 00/U 12/U
BHK 056/081 056/081 055/082 057/087 058/089 059/089 060/084
23/T 23/T 23/T 32/T 00/U 01/U 12/T
SHR 054/087 055/085 054/087 054/089 055/092 055/092 056/086
33/T 34/T 32/T 21/U 10/U 00/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GLASGOW MT
231 PM MDT SAT AUG 10 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
MAIN FORECAST CHALLENGE THIS AFTERNOON AND EVENING SURROUNDS THE
CONVECTIVE POTENTIAL ACROSS NORTHEAST MONTANA WITH VIGOROUS
SHORTWAVE DROPPING DOWN FROM SASKATCHEWAN. PERSISTENT GENERAL
SHOWERS AND THUNDERSTORMS HAVE BEEN ONGOING THROUGHOUT THE
NORTHEASTERN ZONES SINCE LATE THIS MORNING. A FEW OF THESE STORMS
HAVE PRODUCED SMALL HAIL AND BRIEF HEAVY DOWNPOURS. BEST
INSTABILITY WITH HIGHEST CAPE VALUES APPEAR TO BE IN THE
SOUTHEASTERN PORTIONS OF THE CWA. HOWEVER...MODEL FORECAST
SOUNDINGS SHOW A CAP IN PLACE. IN ADDITION...HIGH CLOUDINESS HAS
FILTERED OUT SOME SUNSHINE EARLY THIS AFTERNOON REDUCING
INSOLATION. THIS PLACES A BIG QUESTION MARK IN THIS PART OF THE
FORECAST. ANY STORMS THAT DEVELOPED IN THIS AREA WERE EXPECTED TO
BECOME STRONG. IT IS STILL UNCLEAR HOW THE LATE AFTERNOON AND
EVENING WILL UNFOLD. MODEL GUIDANCE CONTINUES TO SHOW SUPPORT FOR
CONVECTION BUT RECENT HRRR SOLUTIONS HAVE BACKED DOWN JUST A BIT.
WILL KEEP THE FORECAST GOING FOR NOW AS IS BUT WILL NEED TO
MONITOR FOR CHANGES. GIVEN INSTABILITY...ANY STORMS THAT DEVELOP
AND/OR PUSH INTO THE SOUTHEAST LATER THIS AFTERNOON OR EVENING MAY
BE CAPABLE OF SMALL HAIL AND GUSTY WINDS. CUMUMULUS FIELD
BEGINNING TO SHOW UP IN VISIBLE SATELLITE IMAGERY ACROSS RICHLAND
COUNTY. THERE WAS MUCH MORE IN THE WAY OF SUNSHINE IN
RICHLAND...NORTHERN DAWSON...AND NORTHERN WIBAUX COUNTY AND THIS
IS THE AREA THAT WILL NEED TO BE WATCHED MOST CLOSELY FOR STRONGER
STORMS. NOT GOING TO INTRODUCE SEVERE WORDING INTO THE GRIDS AS
THERE IS JUST TOO MUCH UNCERTAINTY. IN ADDITION...SPC SSEO
SUGGESTS SEVERE POTENTIAL WOULD BE FURTHER SOUTH AND EAST OF THE
FORECAST REGION. WILL NOT RULE OUT AN ISOLATED SEVERE THUNDERSTORM
TODAY BUT POTENTIAL FOR THAT SHOULD BE BETTER TO THE SOUTH AND
EAST OF THE CWA. ASIDE FROM THE ROBUST SHORTWAVE PUSHING THROUGH FROM
SASKATCHEWAN...ADDITIONAL SHOWERS/THUNDERSTORMS ARE POSSIBLE
ACROSS PHILLIPS COUNTY WITH A VERY WEAK SHORTWAVE EMBEDDED IN THE
UPPER FLOW PATTERN PUSHING THROUGH THIS EVENING. WILL KEEP
ISOLATED SHOWERS/STORMS IN THOSE LOCATIONS THIS EVENING.
SUNDAY INTO MONDAY...10/12Z MODEL GUIDANCE CONTINUES TO BRING UPPER
RIDGE CLOSER INTO THE CWA. THIS SHOULD PROMOTE LARGE SCALE
SUBSIDENCE. WILL NOT RULE OUT DIURNALLY DRIVEN CONVECTION BUT WITH
LITTLE MOISTURE AND NOT LIFTING MECHANISM...NOTHING MORE THAN
ISOLATED IS ANTICIPATED. TEMPERATURES SHOULD ALSO GRADUALLY
INCREASE WITH RISING HEIGHTS AND WARMING 850MB TEMPERATURES WITH
THE RIDGE BUILDING IN. MALIAWCO
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE GRADUALLY BUILDS INTO MONTANA DURING THE EXTENDED
PERIOD.
FOR TUESDAY AND WEDNESDAY...THERE WILL BE A SLOW MOVING WARM FRONT
WHICH WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS AT TIMES.
THE STORMS WILL BE PARTLY DRIVEN BY DAYTIME INSTABILITY AND PARTLY
DRIVEN BY SHORTWAVES THAT OVERTOP THE RIDGE AXIS. MODELS TIME THE
WAVES DIFFERENTLY WHICH RESULTS IN MODELS TIMING THE STORMS
DIFFERENTLY. AT THIS POINT... IT LOOKS LIKE THE BEST CHANCE FOR
STORMS WILL BE WEDNESDAY AFTERNOON AND EVENING WHEN THE WARM FRONT
IS OVER EASTERN MONTANA. IT MAY BE UNSTABLE ENOUGH FOR SEVERE
STORMS ON WEDNESDAY. THE CHANCES OF SHOWERS AND THUNDERSTORMS
COULD LINGER INTO THURSDAY DEPENDING ON HOW FAST THE FRONT MOVES
EAST.
BY FRIDAY...THE UPPER RIDGE TAKES CONTROL OF THE WEATHER.
TEMPERATURES WILL WARM TO NEAR 90 POSSIBLY WARMER BOTH FRIDAY AND
SATURDAY WITH LITTLE OR NO CHANCE OF PRECIPITATION. FORRESTER
&&
.AVIATION...
VFR. SCATTERED THUNDERSTORMS WILL BE AFFECTING SOME OF THE AIRPORTS
THIS AFTERNOON. EXPECT GUSTY/ERRATIC WINDS...BRIEF HEAVY RAIN AND
POSSIBLY HAIL. CLEARING AND LIGHT WINDS MAY LEAD TO PATCHY FOG
LATE TONIGHT. TFJ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
1003 AM MDT SAT AUG 10 2013
.UPDATE...
NO MAJOR ADJUSTMENTS TO THE FORECAST THIS MORNING. TWEAKED POPS
TO LINE UP BETTER WITH SURROUNDING OFFICES...ADJUSTED WINDS AND
CLOUD COVER FOR CURRENT TRENDS. RIDGE OF HIGH PRESSURE WILL BUILD
TO THE WEST OF THE AREA TODAY...CLIPPING WESTERN ZONES WITH DRIER
AND WARMER AIR. AS THE RIDGE BUILDS TO THE WEST WILL SEE SOME
HEIGHT FALLS TO THE EAST ALLOWING A WEAK DISTURBANCE OVER
NORTHWEST MONTANA TO SLIDE SOUTHEAST AND STRENGTHEN JUST A BIT.
THE APPROACH OF THIS WAVE ALONG WITH WARMER TEMPERATURES TO THE
WEST WILL DEEPEN SURFACE LOW PRESSURE OVER WESTERN ZONES ALLOWING
SLIGHTLY COOLER AIR AND NORTHEAST WINDS TO PUSH WESTWARD THIS
AFTERNOON AND EVENING. THE COMBINATION OF THIS WEAK SURFACE
BOUNDARY AND THE WAVE ALOFT HAS THE MODELS DEVELOPING SCATTERED
CONVECTION OVER THE AREA THIS AFTERNOON AND EVENING. STORMS TO THE
WEST WILL BE HIGH BASED AND LOOK PRETTY DRY SO GUSTY WINDS WILL BE
THE MAIN THREAT WEST OF A HARLOWTON TO COLUMBUS LINE WITH ANY
STORMS. TO THE EAST OF THE LINE HIGHER RH VALUES WILL KEEP STORMS
WET AND HEAVY RAINFALL IS A POSSIBILITY WITH ANY STORMS. OVER FAR
EASTERN ZONES SHEAR PROFILES ARE STRONGER AS THIS AREA CATCHES THE
TAIL END OF AN UPPER LEVEL JET. SHEAR LOOKS TO BE IN THE 30 TO 40
KT RANGE WITH A FEW HI RES MODELS SHOWING STRONGER POCKETS.
HODOGRAPHS SHOW STORM SPLITTING PROFILE WITH RIGHT MOVERS MOVING
PERPENDICULAR TO THE LOW LEVEL INFLOW WHICH MEANS THAT A FEW
LONGER LIVED AND THUS STRONGER CELLS ARE POSSIBLE. CERTAINLY NOT A
HIGH END THREAT BUT WOULD EXPECT A FEW WARNING CALIBER STORMS TO
BE MIXED IN WITH SCATTERED STORM COVERAGE THIS AFTERNOON FOR AREAS
EAST OF ROSEBUD COUNTY. TEMPERATURES TODAY WILL BE IN THE MID TO
UPPER 80S WEST WITH LOW 80S TO MAYBE UPPER 70S EAST. LOTS OF
OUTDOOR EVENTS THIS WEEKEND ACROSS THE AREA SO MAKE SURE TO HAVE A
PLAN TO GET TO SHELTER SHOULD STRONG STORMS DEVELOP TODAY.
CHAMBERS
&&
.SHORT TERM...VALID FOR TDY AND SUN...
A WARMING TREND WILL BEGIN TODAY AND CONTINUE INTO SUN WITH HEIGHT
RISES ALOFT...BUT LOW-LEVEL EASTERLY FLOW WILL KEEP SOME CHANCE OF
STORMS IN THE FORECAST...ESPECIALLY IN SOUTHEASTERN MT.
TODAY...WE WILL KEEP A MENTION OF PATCHY FOG IN THE FORECAST UNTIL
15 UTC FOR MOST OF THE AREA WITH SURFACE DEWPOINT DEPRESSIONS LESS
THAN 10 F OVER PARTS OF THE AREA AS OF 09 UTC. HOWEVER...NOT A LOT
OF SUPPORT EXISTS FOR ITS FORMATION IN GUIDANCE...INCLUDING RECENT
RUNS OF THE HRRR...WHICH OFTEN PICKS UP ON THIS SITUATION. WE ALSO
KEPT LOW POPS IN SOUTHEASTERN MT THROUGH 15 UTC TO ACCOUNT FOR THE
SLOW EXIT OF A WEAK SHORT WAVE IN THAT REGION. THE BIG PICTURE FOR
TODAY WILL FEATURE MODEST HEIGHT RISES ALOFT...AND A WARMING TREND
AT THE SURFACE. WE HAVE SLIGHT CHANCE POPS IN THE FORECAST FOR THE
AFTERNOON EVERYWHERE...BUT THAT WAS ACTUALLY A REDUCTION IN VALUES
FOR SOUTHEASTERN MT BECAUSE IT LOOKS LIKE FORCING FOR STORMS COULD
HOLD OFF UNTIL 00 UTC OR LATER IN THAT AREA. THE EASTERLY FLOW AND
MLCAPE TO 500 J/KG IN SOUTH CENTRAL MT MAY YIELD CONVECTION ACROSS
THE HIGHER TERRAIN THIS AFTERNOON TOO...WITH A TENDENCY FOR ANY OF
THAT ACTIVITY TO MOVE EASTWARD INTO THE LOWER ELEVATIONS SINCE THE
BOUNDARY LAYER SHOULD NOT BE TOO CAPPED. WE CHOSE TO LEAVE POPS IN
THE 20 PERCENT RANGE EVEN IN SOUTH CENTRAL MT THOUGH DESPITE QUITE
A BIT OF SUPPORT FOR STORMS IN HIGH-RESOLUTION GUIDANCE BECAUSE IT
IS POSSIBLE THAT THE SYNOPTIC-SCALE ENVIRONMENT /RISING HEIGHTS AT
500 HPA/ WILL INHIBIT MORE THAN ISOLATED DEVELOPMENT.
TONIGHT...CONFIDENCE IS INCREASING IN THUNDERSTORMS OVER SOUTHEAST
MT DURING THE EVENING AS THE CONVECTIVELY-ACTIVE SHORT WAVE TROUGH
OBSERVED OVER NORTHERN ID ON 09 UTC MOISTURE CHANNEL IMAGES SHEARS
SOUTHEAST INTO THE NORTHERN HIGH PLAINS. SEVERAL MEMBERS OF THE 00
UTC SPC SSEO KEY ON SOUTHEASTERN MT FOR CONVECTION IN THE 00 TO 06
UTC TIME FRAME...AND RECENT RAP RUNS ALSO SIMULATE CONVECTION OVER
THAT AREA /ALBEIT A BIT EARLIER/. FORECAST SOUNDINGS CALL FOR 1000
TO 1500 J/KG OF MLCAPE AND 0-6-KM BULK SHEAR NEAR 40 KT...WHICH IS
SUFFICIENT FOR ORGANIZED SEVERE STORMS. WE CHOSE TO INCLUDE A RISK
OF SEVERE STORMS IN THE FORECAST...BUT WE HAVE TO ADMIT IT REMAINS
VERY CONDITIONAL ON STORMS ACTUALLY FORMING. FINALLY..IF STORMS DO
DEVELOP OVER THE HIGHER TERRAIN IN SOUTH CENTRAL MT THIS AFTERNOON
THEN THEY WILL LIKELY CONTINUE SPREADING EAST THIS EVENING...WHICH
WILL BE THE HIGHEST PROBABILITY FOR BILLINGS TO SEE IMPACTS FROM A
STORM. DEEP-LAYER SHEAR IS WEAKER IN SOUTH CENTRAL MT...BUT WITH A
WELL-MIXED BOUNDARY LAYER...STRONG AND GUSTY WINDS ARE POSSIBLE IF
STORMS DO AFFECT THE AREA.
SUN...A MUCH DRIER AND MORE DEEPLY MIXED AIR MASS WILL SPREAD INTO
SOUTH CENTRAL MT...WITH FORECAST SOUNDINGS SUGGESTING MIXING COULD
LOWER DEWPOINTS INTO THE 20S F IN PLACES LIKE LIVINGSTON. EASTERLY
FLOW WILL MAINTAIN DEEPER MOISTURE OVER SOUTHEASTERN MT...WITH LOW
AND CONDITIONAL POPS FOR STORMS THUS WARRANTED IN THAT AREA. HIGHS
WILL TAKE ANOTHER MOVE UPWARD WITH MORE WARMING ALOFT. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
ONLY SMALL ADJUSTMENTS WERE MADE TO THE EXTENDED PERIOD FORECASTS
FOR THIS MORNINGS PACKAGE. CONFIDENCE IS HIGH IN AN AMPLIFIED
RIDGE OVER THE REGION WITH PRECIPITABLE WATER HIGHEST IN THE EAST
AND LOWEST IN THE WEST. THEREFORE...THE CHANCE OF MEASURABLE
PRECIPITATION WILL BE HIGHER IN THE EASTERN ZONES. WE CONTINUE TO
SEE PERIODS OF NOCTURNAL STORMS POSSIBLE IN THE CENTRAL AND EAST
DUE TO LOW LEVEL JET ACTIVITY. HIGH PRESSURE ALOFT DOES BREAK
DOWN AT MIDWEEK AS A SHORT WAVE ROUNDS THE RIDGE AND INTERACTS
WITH THE MOISTURE OVER THE EAST FOR A BETTER CHANCE OF
THUNDERSTORMS. THE RIDGE THEN STRENGTHENS LEADING TO ABOVE NORMAL
TEMPERATURES. I BEGAN TRENDING AFTERNOON HIGHS UP FOR THE LATTER
PART OF NEXT WEEK BASED ON THESE TRENDS. BT
&&
.AVIATION...
EXPECT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO IMPACT
THE AREA THIS AFTERNOON AND EVENING...WITH LOCALLY REDUCED
VISIBILITIES AND CEILINGS. VFR CONDITIONS WILL PREVAIL OTHERWISE
TODAY. PATCHY FOG IS POSSIBLE AGAIN LATE TONIGHT FROM KBIL EAST.
JKL
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 084 059/089 060/089 060/087 060/087 059/091 059/092
2/T 31/U 12/T 22/T 22/T 21/U 10/U
LVM 086 051/090 051/088 051/088 052/087 052/089 051/090
2/T 21/U 12/T 22/T 22/T 21/U 11/U
HDN 087 057/092 059/091 060/089 059/089 058/092 059/095
2/T 32/T 12/T 32/T 22/T 21/U 11/U
MLS 083 060/087 063/089 063/088 061/088 060/091 062/094
2/T 42/T 22/T 22/T 23/T 31/U 11/U
4BQ 084 055/088 059/089 061/088 058/087 057/090 059/093
2/T 42/T 22/T 33/T 33/T 31/U 11/U
BHK 078 056/082 058/084 059/083 057/083 057/087 058/089
2/T 42/T 22/T 22/T 23/T 32/T 11/U
SHR 084 054/089 054/088 057/087 055/087 055/088 055/091
2/T 32/T 22/T 23/T 33/T 31/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GLASGOW MT
944 AM MDT SAT AUG 10 2013
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
UPDATE...
PLACED THE ENTIRE CWA IN ISOLATED POPS THIS MORNING WITH THUNDER
MENTION GIVEN CURRENT RADAR OBSERVATIONS. FORECAST SOUNDINGS
INDICATE HIGHEST CAPE THIS AFTERNOON/EVENING ACROSS THE
SOUTHEASTERN ZONES. HRRR INDICATES CONVECTION INITIATION ACROSS
THE CWA AND PUSHING THROUGH THE EAST/SOUTHEAST AS WELL. THIS HAS
ADDITIONAL SUPPORT FROM THE 10/00Z ECMWF AS WELL AS 10/12Z NAM/GFS
WHICH ALL HAVE QPF IN THE SOUTHEAST TODAY. WILL PLACE THESE AREAS
IN SCATTERED SHOWERS AND THUNDERSTORMS. VISIBLE SATELLITE IMAGERY
SHOWS MORE IN THE WAY OF SUNSHINE THERE AS WELL THIS MORNING WHICH
COULD CONTINUE TO DESTABILIZE THE ENVIRONMENT...MAKING IT MORE
CONDUCIVE FOR A FEW STORMS TO BECOME ON THE STRONGER SIDE. THE
SSEO FROM SPC SHOWS BEST POTENTIAL FOR SEVERE STORMS TO BE JUST TO
THE SOUTH AND EAST OF THE CWA SO WILL NOT INCLUDE SEVERE WORDING
IN THE GRIDS. DID PLACE GUSTY WINDS/SMALL HAIL HOWEVER...MAINLY
SOUTH OF THE MISSOURI RIVER. BEST CONFIDENCE FOR STRONGER STORMS
IS AGAIN IN THE SOUTHEASTERN PORTIONS OF THE CWA FOR THIS
AFTERNOON AND EVENING. MALIAWCO
PREVIOUS SHORT TERM DISCUSSION... WATER VAPOR IMAGERY AND 500 MB
HEIGHT FIELD SHOWS THE SLOWLY EVOLVING WEATHER PATTERN ACROSS THE
CONUS. THE CLOSED UPPER LOW PRESSURE SYSTEM OVER THE PACIFIC
COASTLINE IS SLOWLY WEAKENING AS IT MOVES NORTHWARD. THE STRONGER
WAVES OF THE HUDSON BAY UPPER LOW COMPLEX ARE SPINNING A BIT
FURTHER EASTWARD THAN THEY WERE BEFORE TODAY. BOTH OF THESE
MOVEMENTS ALLOWS THE RIDGE OF HIGH PRESSURE OVER THE SOUTHERN HIGH
PLAINS AND SOUTHERN ROCKIES REGIONS TO SLOWLY BUILD NORTHWARD.
THIS WEATHER REGIME EVOLVEMENT IS EXPECTED TO CONTINUE...PLACING
THE UPPER LEVEL RIDGE AXIS OVER MONTANA BY THE END OF THIS
FORECAST PERIOD...WHICH WILL GENERALLY ALLOW TEMPERATURES TO CLIMB
ABOVE NORMAL THROUGH THE END OF NEXT WEEK.
THE FORECAST CHALLENGES WILL FOCUS ON THE TIMING...PLACEMENT...AND
INTENSITY OF ANY THUNDERSTORMS WHICH DO HAPPEN TO DEVELOP.
ALTHOUGH ALL BUT THE NORTHEASTERN THIRD OF OUR CWA IS OUTLINED FOR
GENERAL THUNDERSTORMS LATER TODAY AND TONIGHT...THE LACK OF
CONSISTENCY BETWEEN DIFFERENT MODEL SOLUTIONS AND EVEN BETWEEN ANY
INDIVIDUAL MODELS SUBSEQUENT RUNS SIGNIFICANTLY REDUCES THE
FORECAST CONFIDENCE. FEEL IT WOULD BE MOST PRUDENT TO EMPHASIZE
THE FEW SIMILARITIES WITH SLIGHTLY HIGHER POPS...BUT FILL IN THE
REST WITH ISOLATED SPRINKLES AT TIMES.
FOR EXAMPLE...THE NAM AND EC ARE EMPHASIZING THE STORMS TONIGHT
MORE WHILE THE GFS IS VIRTUALLY QUIET. THIS SAME SCENARIO SETS UP
FOR SUNDAY NIGHT AS WELL. EVEN THOUGH SOME INSTABILITY IS
PRESENT...I WOULD NOT IMAGINE MUCH WILL COME OF IT GIVEN THE LACK
OF MODEL AGREEMENT. BMICKELSON
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE GRADUALLY BUILDS INTO MONTANA DURING THE EXTENDED
PERIOD.
FOR TUESDAY AND WEDNESDAY...THERE WILL BE A SLOW MOVING WARM FRONT
WHICH WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS AT TIMES.
THE STORMS WILL BE PARTLY DRIVEN BY DAYTIME INSTABILITY AND PARTLY
DRIVEN BY SHORTWAVES THAT OVERTOP THE RIDGE AXIS. MODELS TIME THE
WAVES DIFFERENTLY WHICH RESULTS IN MODELS TIMING THE STORMS
DIFFERENTLY. AT THIS POINT... IT LOOKS LIKE THE BEST CHANCE FOR
STORMS WILL BE WEDNESDAY AFTERNOON AND EVENING WHEN THE WARM FRONT
IS OVER EASTERN MONTANA. IT MAY BE UNSTABLE ENOUGH FOR SEVERE
STORMS ON WEDNESDAY. THE CHANCES OF SHOWERS AND THUNDERSTORMS
COULD LINGER INTO THURSDAY DEPENDING ON HOW FAST THE FRONT MOVES
EAST.
BY FRIDAY...THE UPPER RIDGE TAKES CONTROL OF THE WEATHER.
TEMPERATURES WILL WARM TO NEAR 90 POSSIBLY WARMER BOTH FRIDAY AND
SATURDAY WITH LITTLE OR NO CHANCE OF PRECIPITATION. FORRESTER
&&
.AVIATION...
VFR. EXPECT SCATTERED SHOWERS AND/OR THUNDERSTORMS LATER
TODAY...ESPECIALLY TO KGDV. EXPECT GUSTY/ERRATIC WINDS...BRIEF
HEAVY RAIN AND POSSIBLY HAIL. TFJ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS BILLINGS MT
327 AM MDT SAT AUG 10 2013
.SHORT TERM...VALID FOR TDY AND SUN...
A WARMING TREND WILL BEGIN TODAY AND CONTINUE INTO SUN WITH HEIGHT
RISES ALOFT...BUT LOW-LEVEL EASTERLY FLOW WILL KEEP SOME CHANCE OF
STORMS IN THE FORECAST...ESPECIALLY IN SOUTHEASTERN MT.
TODAY...WE WILL KEEP A MENTION OF PATCHY FOG IN THE FORECAST UNTIL
15 UTC FOR MOST OF THE AREA WITH SURFACE DEWPOINT DEPRESSIONS LESS
THAN 10 F OVER PARTS OF THE AREA AS OF 09 UTC. HOWEVER...NOT A LOT
OF SUPPORT EXISTS FOR ITS FORMATION IN GUIDANCE...INCLUDING RECENT
RUNS OF THE HRRR...WHICH OFTEN PICKS UP ON THIS SITUATION. WE ALSO
KEPT LOW POPS IN SOUTHEASTERN MT THROUGH 15 UTC TO ACCOUNT FOR THE
SLOW EXIT OF A WEAK SHORT WAVE IN THAT REGION. THE BIG PICTURE FOR
TODAY WILL FEATURE MODEST HEIGHT RISES ALOFT...AND A WARMING TREND
AT THE SURFACE. WE HAVE SLIGHT CHANCE POPS IN THE FORECAST FOR THE
AFTERNOON EVERYWHERE...BUT THAT WAS ACTUALLY A REDUCTION IN VALUES
FOR SOUTHEASTERN MT BECAUSE IT LOOKS LIKE FORCING FOR STORMS COULD
HOLD OFF UNTIL 00 UTC OR LATER IN THAT AREA. THE EASTERLY FLOW AND
MLCAPE TO 500 J/KG IN SOUTH CENTRAL MT MAY YIELD CONVECTION ACROSS
THE HIGHER TERRAIN THIS AFTERNOON TOO...WITH A TENDENCY FOR ANY OF
THAT ACTIVITY TO MOVE EASTWARD INTO THE LOWER ELEVATIONS SINCE THE
BOUNDARY LAYER SHOULD NOT BE TOO CAPPED. WE CHOSE TO LEAVE POPS IN
THE 20 PERCENT RANGE EVEN IN SOUTH CENTRAL MT THOUGH DESPITE QUITE
A BIT OF SUPPORT FOR STORMS IN HIGH-RESOLUTION GUIDANCE BECAUSE IT
IS POSSIBLE THAT THE SYNOPTIC-SCALE ENVIRONMENT /RISING HEIGHTS AT
500 HPA/ WILL INHIBIT MORE THAN ISOLATED DEVELOPMENT.
TONIGHT...CONFIDENCE IS INCREASING IN THUNDERSTORMS OVER SOUTHEAST
MT DURING THE EVENING AS THE CONVECTIVELY-ACTIVE SHORT WAVE TROUGH
OBSERVED OVER NORTHERN ID ON 09 UTC MOISTURE CHANNEL IMAGES SHEARS
SOUTHEAST INTO THE NORTHERN HIGH PLAINS. SEVERAL MEMBERS OF THE 00
UTC SPC SSEO KEY ON SOUTHEASTERN MT FOR CONVECTION IN THE 00 TO 06
UTC TIME FRAME...AND RECENT RAP RUNS ALSO SIMULATE CONVECTION OVER
THAT AREA /ALBEIT A BIT EARLIER/. FORECAST SOUNDINGS CALL FOR 1000
TO 1500 J/KG OF MLCAPE AND 0-6-KM BULK SHEAR NEAR 40 KT...WHICH IS
SUFFICIENT FOR ORGANIZED SEVERE STORMS. WE CHOSE TO INCLUDE A RISK
OF SEVERE STORMS IN THE FORECAST...BUT WE HAVE TO ADMIT IT REMAINS
VERY CONDITIONAL ON STORMS ACTUALLY FORMING. OTHERWISE...IF STORMS
DEVELOP OVER THE HIGHER TERRAIN IN SOUTH CENTRAL MT THIS AFTERNOON
THEN THEY WILL LIKELY CONTINUE SPREADING EAST THIS EVENING...WHICH
WILL BE THE HIGHEST PROBABILITY FOR BILLINGS TO SEE IMPACTS FROM A
STORM. DEEP-LAYER SHEAR IS WEAKER IN SOUTH CENTRAL MT...BUT WITH A
WELL-MIXED BOUNDARY LAYER...STRONG AND GUSTY WINDS ARE POSSIBLE IF
STORMS DO AFFECT THE AREA.
SUN...A MUCH DRIER AND MORE DEEPLY MIXED AIR MASS WILL SPREAD INTO
SOUTH CENTRAL MT...WITH FORECAST SOUNDINGS SUGGESTING MIXING COULD
LOWER DEWPOINTS INTO THE 20S F IN PLACES LIKE LIVINGSTON. EASTERLY
FLOW WILL MAINTAIN DEEPER MOISTURE OVER SOUTHEASTERN MT...WITH LOW
AND CONDITIONAL POPS FOR STORMS THUS WARRANTED IN THAT AREA. HIGHS
WILL TAKE ANOTHER MOVE UPWARD WITH MORE WARMING ALOFT. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
ONLY SMALL ADJUSTMENTS WERE MADE TO THE EXTENDED PERIOD FORECASTS
FOR THIS MORNINGS PACKAGE. CONFIDENCE IS HIGH IN AN AMPLIFIED
RIDGE OVER THE REGION WITH PRECIPITABLE WATER HIGHEST IN THE EAST
AND LOWEST IN THE WEST. THEREFORE...THE CHANCE OF MEASURABLE
PRECIPITATION WILL BE HIGHER IN THE EASTERN ZONES. WE CONTINUE TO
SEE PERIODS OF NOCTURNAL STORMS POSSIBLE IN THE CENTRAL AND EAST
DUE TO LOW LEVEL JET FORMATION. HIGH PRESSURE ALOFT DOES BREAK
DOWN AT MIDWEEK AS A SHORT WAVE ROUNDS THE RIDGE AND INTERACTS
WITH THE MOISTURE OVER THE EAST FOR A BETTER CHANCE OF
THUNDERSTORMS. THE RIDGE THEN STRENGTHENS LEADING TO ABOVE NORMAL
TEMPERATURES. I BEGAN TRENDING AFTERNOON HIGHS UP FOR THE LATTER
PART OF NEXT WEEK BASED ON THESE TRENDS. BT
&&
.AVIATION...
VFR CONDITIONS WILL GENERALLY PREVAIL OVER THE FORECAST TERMINALS
THROUGH 18Z. SHOWERS AND THUNDERSTORMS CAN BE EXPECTED TO DEVELOP
IN THE AFTERNOON HOURS WITH LOCALLY REDUCED VISIBILITY AND
CEILINGS IN THUNDERSTORMS. THUNDERSTORMS ACTIVITY IS EXPECTED TO
DIMINISH BY 03Z. BT
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 086 059/089 060/089 060/087 060/087 059/091 059/092
2/T 31/U 12/T 22/T 22/T 21/U 10/U
LVM 088 051/090 051/088 051/088 052/087 052/089 051/090
2/T 21/U 12/T 22/T 22/T 21/U 11/U
HDN 088 057/092 059/091 060/089 059/089 058/092 059/095
2/T 32/T 12/T 32/T 22/T 21/U 11/U
MLS 085 060/087 063/089 063/088 061/088 060/091 062/094
2/T 42/T 22/T 22/T 23/T 31/U 11/U
4BQ 085 055/088 059/089 061/088 058/087 057/090 059/093
2/T 42/T 22/T 33/T 33/T 31/U 11/U
BHK 079 056/082 058/084 059/083 057/083 057/087 058/089
2/T 42/T 22/T 22/T 23/T 32/T 11/U
SHR 086 054/089 054/088 057/087 055/087 055/088 055/091
2/T 32/T 22/T 23/T 33/T 31/U 11/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1055 PM MDT Fri Aug 9 2013
Aviation Section Updated.
.UPDATE...
Scattered afternoon thunderstorms dissipated with sunset. However,
an upper level shortwave feature lifting northward through western
Montana is associated with a line of thunderstorms from Missoula to
Helena and Bozeman. Evening HRRR guidance splits a portion of the
shortwave to the east and brings precipitation through N. central MT
through 12Z Saturday morning. Satellite and radar trends show this
split as thunderstorms in NW Montana are drifting NW while those in
the Helena area are drifting NE. RUC and NAM guidance do not support
this nocturnal activity as thunderstorms encounter the relatively
cooler and more stable air mass in place over N. central MT. Raised
POPs along the Rocky Mountain front for tonight to reflect these
trends. Nutter
&&
.AVIATION...
UPDATED 0455Z.
Late evening thunderstorm activity has spread a mid-level overcast
across north-central MT, with a line of rain showers over the
mountains southwest of KGTF. VFR conditions prevail except for
possible MFVR near these rain showers. Remaining cloud cover will
break after dawn, allowing the airmass to destabilize with another
round of scattered afternoon thunderstorms. Gusty surface winds
should be expected near thunderstorms but otherwise, winds will
remain light.
&&
.PREV DISCUSSION...
/ISSUED 550 PM MDT Fri Aug 9 2013/
Tonight through Sunday...Monsoonal moisture continues to be drawn
up and across southern Montana this afternoon resulting in the
development of scattered thunderstorms. Moisture is present as
well as decent CAPE values but the shear environment is marginal
at best. As a result, the storms are fairly slow moving and
generally low-topped. With precipitable water values continuing
around an inch or so, heavy rains are possible with these
thunderstorms. Convective activity should gradually end by
midnight with clearing skies. Saturday looks to be a similar day
to today as monsoonal moisture will continue to move north.
Thunderstorms will develop again Saturday afternoon and will be a
bit more widespread in areal coverage. Isolated to scattered
thunderstorms will continue Sunday afternoon and evening as
conditions will change little through the weekend. Temperatures
will warm over the weekend with readings slightly above seasonal
averages. Emanuel
Sunday night through Friday...Early in the week an upper ridge is
forecast to be over the Rockies with southwest to west flow aloft
over the forecast area. Expect a few weather disturbances to be
embedded in the flow aloft but the models are not in good agreement
with their details so will employ a broadbrush approach to the
forecast. There is some evidence from the models that southwest
Montana could have a drier airmass in comparison to locations
farther north so during the afternoon and evening will generally go
with isolated thunderstorms over southwest Montana and scattered
thunderstorms over northwest Montana. Also will play the diurnal
card and have lower chances of precipitation during the late night
and morning relative to during the afternoon and evening. Thursday
the latest GEM (Canadian) and ECMWF (European) model runs redevelop
the upper ridge west of the forecast area and then move it over the
forecast area by early Friday. The GFS (U.S.) model run does not
forecast this redevelopment and continues a southwest flow aloft.
However other forecast guidance from the GFS does show some support
for the ECMWF solution for Friday. Will go with slightly lower
chances of precipitation later in the week relative to early in the
week due to the possibility of an upper ridge over the forecast area
later in the week. Expect little day-to-day change in high
temperatures with highs in the 80s.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 54 86 55 88 / 20 30 20 20
CTB 51 82 52 83 / 20 20 20 50
HLN 56 88 57 89 / 30 30 20 20
BZN 49 88 49 88 / 30 30 20 20
WEY 37 79 37 78 / 20 20 10 10
DLN 48 85 49 85 / 20 30 20 20
HVR 53 83 55 85 / 10 20 20 20
LWT 52 81 54 83 / 30 30 30 20
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
621 PM CDT SUN AUG 11 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 245 PM CDT SUN AUG 11 2013
A SURFACE TROUGH OF LOW PRESSURE ACROSS NORTHERN NEBRASKA THIS
AFTERNOON IS EXPECTED TO PROVIDE ENOUGH CONVERGENCE FOR THE
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE OUTLOOK
AREA BY LATE AFTERNOON AS THE CAP BEGINS TO WEAKEN. WHILE THE
INSTABILITY VALUES REMAIN HIGH...ON THE ORDER OF 3000 J/KG OF MU
CAPE...THE WIND SHEAR VALUES ARE VERY WEAK...AND PRIMARY CONCERN
WITH THESE STORMS WILL BE THE POTENTIAL FOR LARGE HAIL. MODELED
SOUNDINGS ALSO INDICATE AN INVERTED V ATMOSPHERIC PROFILE FOR THE
LATE AFTERNOON AND EARLY EVENING HOURS...SO STRONG WIND GUSTS MAY
ALSO BE A CONCERN. NOT SURPRISINGLY...THE ENTIRE OUTLOOK ARE
REMAINS IN A SLIGHT RISK FOR SEVERE WEATHER FROM SPC...WITH LARGE
HAIL AND WINDS BEING THE PRIMARY CONCERN.
SOME OF THE LATEST MODEL RUNS ARE INDICATING THE CONVECTION
CURRENTLY DEVELOPING ACROSS THE HIGH PLAINS AND ASSOCIATED WITH A
PASSING SHORTWAVE IN WV IMAGERY...WILL EVENTUALLY MERGE WITH
CONVECTION IN PROXIMITY OF THE SURFACE TROUGH...WHICH COULD RESULT
IN AN ACTIVE EVENING...PRECIPITATION WISE...ACROSS THE LOCAL
AREA. THE 12Z WRF APPEARS TO BE THE MOST AGGRESSIVE WITH THE
SCENARIO...AND THE 18Z RAP ALSO HINTING AT A SOLUTION SIMILAR TO
THIS...SO FELT CONFIDENT ENOUGH TO INCREASE POPS THROUGH THE EARLY
EVENING HOURS INTO THE 50 PERCENT RANGE ACROSS MOST OF THE AREA.
OTHERWISE...WITH THE SLOW MOVEMENT OF ANY STORMS THAT DO
DEVELOP...HEAVY RAINFALL WILL ALSO BE A CONCERN...AND CONTINUED
WITH THE POTENTIAL FOR VERY LOCALIZED FLOODING THIS EVENING AND
OVERNIGHT.
FOR MONDAY...EXPECT A MOSTLY DRY START TO THE DAY...WITH
INCREASING CHANCES FOR PRECIPITATION BY AFTERNOON AS WE COULD SEE
SOME CONVECTION REDEVELOP IN THE VICINITY OF THE STALLED OUT
FRONT/TROUGH WHICH WILL THEN BE ACROSS NORTH CENTRAL KANSAS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 245 PM CDT SUN AUG 11 2013
COOLER THAN NORMAL SUMMER WEATHER WILL SETTLE IN ACROSS OUR REGION
FOR MUCH OF THE WORKWEEK IN A NORTHWEST FLOW REGIME ACROSS THE
CENTRAL PLAINS. WARMER AIR WILL RESIDE TO THE WEST FM THE DESERT SW
NORTH ACROSS THE ROCKIES...WHILE TO THE EAST...A TROUGH NEAR THE
HUDSON BAY WILL DEEPEN AND TRANSLATE ACROSS THE EASTERN CONUS.
COOLER AIR WILL BACK IN ACROSS THE PLAINS FM THE UPPER MIDWEST AND A
1022ISH MB SFC HIGH WILL BUILD SOUTH FM THIS AREA ONTO THE PLAINS...AND
WILL REINFORCE THE COOLER AIRMASS UNTIL AROUND THE THURSDAY TIME
FRAME. BY THE END OF THE WEEK AND HEADING INTO THE WEEKEND...THE
SFC RIDGE AXIS SLIDES EAST AND THE UPPER RIDGE OVER THE ROCKIES WILL
BEGINS TO BUILD TOWARDS THE PLAINS AND TEMPERATURES WILL BEGIN TO
MODERATE CLOSER TO SEASONAL NORMALS.
FOR CONVECTIVE POTENTIAL...CANNOT RULE OUT TSTM CHANCES DURING THIS
TIME FRAME...WITH DEVELOPMENT DEPENDENT UPON BOUNDARY LOCATIONS AND
TIMING OF WAVES. ON MONDAY...A FEW STORMS MAY LINGER IN THE
MORNING...WITH REDEVELOPMENT POSSIBLE DURING THE DAY ALONG A BACK
DOOR COOL FRONTAL BOUNDARY AND ALSO TO THE WEST IN AN UPSLOPE FLOW
REGIME. A STRONG TO SEVERE STORM IS POSSIBLE IN SUFFICIENT
INSTABILITY...BUT SHEAR REMAINS WEAK. THE BETTER PCPN CHCS BEGIN TO
FOCUS TO OUR WEST THROUGH MID WEEK...WITH SOME POTENTIAL FOR HIGH
PLAINS CONVECTION TO MIGRATE EAST TOWARDS OUR WESTERN CWA. AS
PATTERN CONTINUES TO AMPLIFY...FOCUS TURNS MORE TO TIMING OF WAVES
TOPPING RIDGE AND CROSSING THE PLAINS...WITH HIT OR MISS CHCS FOR
THE OUTER PERIODS...BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE
POPS.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 621 PM CDT SUN AUG 11 2013
VFR CONDITIONS FORECAST FORECAST THROUGH 09Z...MVFR 09Z-14Z...AND
VFR 14Z ONWARD.
THUNDERSTORM ACTIVITY WILL REMAIN POSSIBLE AT/NEAR GRI THROUGH
04Z...THUS THE VCTS IN THE TAF THROUGH 04Z. GUIDANCE DOES HINT AT
MVFR VISIBILITY RESTRICTION IN FOG TOWARDS DAYBREAK MONDAY...THUS
THE MVFR FORECAST 09-14Z. THE SURFACE WIND WILL REMAIN LIGHT AND
VARIABLE TONIGHT...BECOMING MORE ESTABLISHED FROM THE EAST DURING
THE DAY MONDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...SAR
LONG TERM...FAY
AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
244 AM CDT SAT AUG 10 2013
.UPDATE...
ISSUED AT 242 AM CDT SAT AUG 10 2013
UPDATED THE FORECAST OVERNIGHT TO INCLUDE SOME SMALL CHANCES OF
SHOWERS IN THE FAR NORTHERN CWA...BUT THESE DO NOT APPEAR TO BE
LASTING LONG AND SHOWING SIGNS OF WANING.
UPDATE ISSUED AT 941 PM CDT FRI AUG 9 2013
TRIMMED BACK POPS FOR THE TONIGHT PERIOD...MAINLY TO AREAS
CONFINED TO OUR NORTHWESTERN COUNTIES. THESE SHOWERS SHOULD N0T
LAST PAST MIDNIGHT AS MESOSCALE ANALYSIS INDICATES AN INCREASE IN
CAPPING ACROSS AREAS WHERE CURRENT THUNDERSTORM ACTIVITY IS
ONGOING. ALSO TRIMMED BACK THE PATCHY FOG TO ACCOUNT FOR INCREASE
CLOUD COVER ACROSS OUR NORTH...WHICH SHOULD INHIBIT FOG IN THESE
AREAS. THE PATCHY FOG STILL INCLUDES THE TRI-CITIES AND AREAS
SOUTH OF I-80...WITH A TIME FRAME FROM ROUGHLY 08Z TO 13Z THIS
MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 345 PM CDT FRI AUG 9 2013
THE PRIMARY ISSUES DURING THE NEXT 24 HOURS INVOLVES ISOLATED AND
LIKELY NON-SEVERE SHOWER/STORM DEVELOPMENT INTO THIS
EVENING...AND WHETHER OR NOT ANY IMPACTFUL FOG MIGHT DEVELOP AGAIN
OVERNIGHT. HAVE MAINTAINED A SHOWER/STORM-FREE FORECAST CWA-WIDE
FROM LATE THIS EVENING THROUGH SATURDAY AFTERNOON.
20Z OBJECTIVE SURFACE ANALYSIS REVEALS A VERY SUBTLE...WEAK COLD
FRONT ALIGNED GENERALLY EAST-WEST ACROSS THE HEART OF THE NEB
CWA...ALTHOUGH ONE HAS TO LOOK PRETTY TO FIND IT...AS ALL IT
REALLY DOES IS SEPARATE A LIGHT EAST-NORTHEAST BREEZE FROM A LIGHT
EAST TO EAST-SOUTHEAST ONE. THIS LIGHT FLOW WITH SUSTAINED BREEZES
MOST ALL AREAS NO MORE THAN 5-10 MPH IS A RESULT OF BROAD SURFACE
HIGH PRESSURE OVER THE REGION...WITH THE CORE OF THE PARENT HIGH
AROUND 1027 MILLIBARS CENTERED WELL TO THE NORTH OVER
SASKATCHEWAN. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL
DATA REVEALS RATHER WEAK FLOW ALOFT OVER THE CWA...GENERALLY
WESTERLY UP AT 300MB...NORTHERLY AT 500 MB...AND EVEN FARTHER DOWN
FROM THE EAST-NORTHEAST AT 700MB. ON THE LARGE SCALE...THE CENTRAL
PLAINS LIES IN THE INTERFACE BETWEEN A BROAD TROUGH AND EMBEDDED
VIGOROUS SHORTWAVE TRACKING EAST ACROSS SOUTHEAST CANADA...AND A
RIDGE AXIS EXTENDING EAST-WEST ACROSS THE SOUTHERN CONUS AND THEN
NORTHWARD INTO THE ROCKIES. ON A MORE REGIONAL LEVEL...A LOW-
AMPLITUDE MID LEVEL DISTURBANCE IS LIFTING OUT ACROSS EASTERN
KS/WESTERN MO. OTHER VERY SUBTLE DISTURBANCES APPEAR TO BE
RIPPLING OUT OF THE WY AREA TOWARD WESTERN NEB/SOUTHWEST SD...AND
HELPING TO KICK OFF STORMS IN THE NORTHERN PANHANDLE.
LOCALLY...JUST WITHIN THE PAST HOUR A FEW SMALL...ISOLATED
SHOWERS/POSSIBLY WEAK STORMS HAVE BUBBLED UP OVER DAWSON/BUFFALO
COUNTIES BUT HAVE SHOWED LITTLE SIGN OF MAINTAINING ORGANIZATION.
VISIBLE SATELLITE REVEALS PARTLY TO MOSTLY CLOUDY SKIES OVER THE
CWA AT MID-AFTERNOON...WITH A DECENT LOW LEVEL CUMULUS FIELD
ACROSS MUCH OF THE CENTRAL/WEST...AND SOME LINGERING HIGH CIRRUS
STILL GRADUALLY DEPARTING EASTERN COUNTIES. HIGH TEMPS APPEAR TO
BE FAIRLY WELL ON TRACK...WITH MOST AREAS LIKELY TO END UP IN THE
81-84 RANGE.
GOING FORWARD THROUGH THE LATE AFTERNOON HOURS THROUGH
03Z/10PM...HAVE OPTED TO KEEP THINGS SIMPLE AND ADVERTISE A SLIGHT
CHANCE OF SHOWERS/ISOLATED THUNDERSTORMS CWA-WIDE...ALTHOUGH WOULD
ANTICIPATE THE MOST LIKELY LOCALIZED DEVELOPMENT TO CONTINUE
TARGETING THE WESTERN HALF OF THE NEB CWA...WHERE LATEST MESO-
ANALYSIS INDICATES 0-1KM MLCAPE UP TO AROUND 1500 J/KG...AND WITH
LITTLE IF ANY CINH BUT ALSO VERY LIMITED FORCING FOR ASCENT. WITH
DEEP-LAYER SHEAR AVERAGING NO MORE THAN 15-20KT AND MID LEVEL
LAPSE RATES RATHER SHALLOW AT ONLY 5-6 C/KM...THE THREAT FOR
STRONG TO SEVERE STORMS APPEARS TO BE QUITE LIMITED IF NOT NON-
EXISTENT. POST-03Z/10PM...WILL AIM FOR A DRY REST OF THE
NIGHT...AS ANY DIURNAL SUPPORT FOR CONVECTION FROM AFTERNOON
HEATING WILL BE ON THE WANE...AND GIVEN THAT THE MAIN TRACK OF LOW
AMPLITUDE MID LEVEL DISTURBANCES OVERNIGHT SHOULD GENERALLY TARGET
THE NEB/SD BORDER AREA. FURTHERMORE...THE NOSE OF A MODEST 35KT
850MB LOW LEVEL JET CLEARLY AIMS INTO SOUTHERN SD/FAR NORTH CENTRAL
NEB OVERNIGHT...WHICH IS WHERE MOST MODELS INCLUDING THE NAM AND
4M WRF-NMM FOCUS CONVECTION. THAT BEING SAID...WILL HAVE TO KEEP
AN EYE ON THE NORTHWEST CWA AS THE LATEST HRRR MAINTAINS SOME
SANDHILLS CONVECTION WITHIN 50 MILES OF THE CWA THROUGH AROUND
MIDNIGHT...BUT FEEL THIS MAY BE A BIT CLOSER TO HOME THAN IT
ACTUALLY WILL BE. AT THE SURFACE TONIGHT...BREEZES WILL REMAIN
QUITE LIGHT AND AVERAGE UNDER 5 MPH...WHILE GRADUALLY TURNING TO A
SOUTHERLY DIRECTION. GIVEN THE LIGHT WIND SETUP...THERE IS AT
LEAST SOME CONCERN THAT FOG COULD AGAIN DEVELOP AND REDUCE
VISIBILITY TO 1 MILE OR LESS. HOWEVER...THE CONSENSUS OF
MODELS/GUIDANCE IS THAT TONIGHT/S FOG EVENT SHOULDN/T BE AS
DENSE/IMPACTFUL...POSSIBLY DUE TO SLIGHTLY BETTER BETTER MIXING
JUST ABOVE THE SURFACE. FOR NOW...WILL MAINTAIN THE GENERIC PATCHY
FOG MENTION CWA-WIDE FOR THE LATE NIGHT/EARLY MORNING HOURS
INTRODUCED BY THE PREVIOUS SHIFT...BUT WILL DEFER TO THE NEXT FEW
SHIFTS TO POTENTIALLY RAMP UP THIS FOG WORDING IF NEED BE. AS FOR
LOW TEMPS...ACTUALLY NUDGED DOWN 1-2 DEGREES FROM PREVIOUS IN MOST
SPOTS PER A GUIDANCE BLEND...WHICH PUTS MOST AREAS DOWN BETWEEN
57-61 DEGREES.
TURNING TO THE SATURDAY DAYTIME PERIOD 12Z-00Z/7AM-7PM...MAINTAINED
A RAIN-FREE FORECAST CWA-WIDE. IN THE MID/UPPER LEVELS...FAIRLY
WEAK TO MODEST WEST-NORTHWEST FLOW WILL MAINTAIN OVER THE CENTRAL
PLAINS AT/ABOVE 500MB...AND THERE SHOULD BE SOME SUBTLE HEIGHT
RISES AS WELL...AS THE SOUTHERN PLAINS/SOUTHERN ROCKIES RIDGE
EDGES NORTH JUST A BIT. THE PRIMARY MID LEVEL SHORTWAVE TROUGH
TRACK DURING THE DAY WILL BE FROM SD TOWARD SOUTHWEST MN/NORTHWEST
IA...AND THIS DISTURBANCE SHOULD TEAM WITH AN EAST-WEST QUASI-
STATIONARY FRONT SETTING UP NEAR THE NEB/SD BORDER TO FOCUS THE
VAST MAJORITY OF DAYTIME CONVECTION AT LEAST 50-100 MILES NORTH
AND POSSIBLY NORTHWEST OF THE CWA. THE ODDS OF CONVECTION FORMING
LOCALLY WITH DAYTIME HEATING SEEMS SMALLER THAN TODAY GIVEN
SLIGHTLY WARMER TEMPS EVIDENT AT 700MB...DESPITE MODEST MLCAPE
VALUES CLIMBING INTO THE 500-1000 J/KG RANGE PER THE 18Z NAM.
MODEL FORECASTS SOUNDINGS ALSO CLEARLY SHOW A WEAK BUT EVIDENT CAP.
OTHERWISE...ALTHOUGH BY NO MEANS WINDY...THE LATE MORNING-
AFTERNOON HOURS SHOULD FEATURE SOME OF THE MOST NOTICEABLE MODEST
BREEZES FELT IN MOST OF THE CWA IN SEVERAL DAYS...AS A TIGHTENED
PRESSURE GRADIENT TO THE EAST OF HIGH PLAINS LEE TROUGH SHOULD
PROMOTE SUSTAINED SOUTHERLY SPEEDS 10-15 MPH MOST AREAS. GIVEN THE
SOUTHERLY BREEZES...SLIGHTLY WARMER TEMPS AT 850MB...AND LIKELY NO
WORSE THAN PARTLY CLOUDY SKIES...SEE LITTLE REASON WHY HIGH TEMPS
SHOULDN/T BE AT LEAST A TOUCH HIGHER THAN TODAY. AS A
RESULT...NUDGED UP PREVIOUS HIGHS 1-2 DEGREES IN MOST AREAS...WITH
MOST OF THE CWA AIMED FOR FAIRLY UNIFORM HIGHS BETWEEN 83-86
DEGREES.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 344 PM CDT FRI AUG 9 2013
GUIDANCE SUGGESTS QUASI-ZONAL TO NORTHWESTERLY MID TO UPPER LEVEL
FLOW WILL PERSIST OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG
TERM FORECAST PERIOD...WITH THE POSSIBILITY OF MULTIPLE MID LEVEL
PERTURBATIONS MOVING OVER THE AREA. PRECIPITATION CHANCES REMAIN
INTACT THROUGHOUT THE LONG TERM FORECAST PERIOD AS A RESULT.
STARTING SATURDAY NIGHT...THERE ARE SIGNS...PRIMARILY FROM THE
EC...OPERATIONAL GFS AND SREF-MEAN...THAT CENTRAL TO NORTHERN HIGH
PLAINS CONVECTION FROM SATURDAY AFTERNOON/EVENING MAY HOLD TOGETHER
LONG ENOUGH...PRIMARILY DUE TO LOW LEVEL THERMAL ADVECTION ALONG THE
AXIS OF A ~30KT 850MB JET STREAK...TO IMPACT NORTHERN PORTIONS OF
OUR CWA. CONFIDENCE IS NOT OVERLY HIGH THAT MEASURABLE PRECIPITATION
WILL BE REALIZED ACROSS OUR AREA SATURDAY NIGHT AND AS A
RESULT...POPS ONLY IN THE 20-30% RANGE CURRENTLY EXIST. HEADING INTO
THE DAY SUNDAY...LOW LEVEL CONVERGENCE ALONG A LOW LEVEL BAROCLINIC
ZONE/TROUGH COULD PROMOTE ENOUGH LIFT...ALONG WITH A PASSING MID
LEVEL PERTURBATION...TO PROMOTE PRECIPITATION PRODUCTION ACROSS
PORTIONS OF THE REGION. WHERE EXACTLY THE BOUNDARY POSITIONS ITSELF
IS THE BIGGEST QUESTION AT THIS TIME. THE NAM...EC...AND SREF-MEAN
ALL SUGGEST THE BOUNDARY WILL MOVE INTO NORTHERN OR CENTRAL PORTIONS
OF OUR CWA...WHILE THE OPERATIONAL GFS KEEPS THE BOUNDARY TO THE NORTH OF
OUR AREA. GIVEN THE UNCERTAINTY WITH RESPECT TO BOUNDARY
LOCATION...WENT NO HIGHER THAN 20-30% FOR THE DAY SUNDAY. CHANCES
FOR PRECIPITATION...ALBEIT LOW CHANCES DUE TO LOW CONFIDENCE...THEN
CONTINUE ACROSS MUCH OF OUR AREA SUNDAY NIGHT AS THE AXIS OF A
25-30KT 850MB JET STREAK DEVELOPS AND YET ANOTHER MID LEVEL
PERTURBATION POTENTIALLY MOVES OVER PORTIONS OF THE REGION. 20-30%
POPS REMAIN INTACT ACROSS THE AREA SUNDAY NIGHT AS A RESULT.
FINALLY...DURING THE DAY MONDAY...YET ANOTHER WEAK MID LEVEL
PERTURBATION MAY MOVE OVER THE AREA. CONFIDENCE IS LOW WITH RESPECT
TO ANY ONE LOCATION ACROSS THE AREA RECEIVING MEASURABLE
PRECIPITATION BUT RATHER THAN ELIMINATE POPS...WENT AHEAD AND
PRESENTED MOSTLY ~20% POPS TO MUCH OF OUR AREA FOR MONDAY.
MID LEVEL PERTURBATIONS MOVING OVER THE AREA WILL ALSO PROMOTE
CHANCES FOR PRECIPITATION ACROSS OUR AREA MONDAY NIGHT ONWARD AND AS
A RESULT...ALLBLEND PRESENTED POPS RANGING ANYWHERE FROM 20% TO 50%.
AFTER COORDINATION WITH SURROUNDING OFFICES...A FEW MINOR TWEAKS
WERE MADE TO TUESDAY POPS. OTHERWISE...ALLBLEND POPS WERE LEFT
UNCHANGED FOR THE MOST PART DUE TO THE LOW PROBABILITY OF IMPROVING
ON THE ALLBLEND SOLUTION.
DECENT LOW LEVEL MOISTURE...WITH SURFACE DEWPOINTS IN THE UPPER 60S
TO NEAR 70...WILL HELP PROMOTE RESPECTABLE LEVELS OF POTENTIAL
INSTABILITY BOTH SUNDAY AND MONDAY...WITH THE NAM AND OPERATIONAL GFS
BOTH SUGGESTING MUCAPE VALUES IN THE 2500-3500J/KG RANGE. DEEP LAYER
BULK SHEAR DOES NOT APPEAR AS THOUGH IT WILL BE OVERLY
IMPRESSIVE...GENERALLY IN THE 20-25KT RANGE...BUT GIVEN THE EXPECTED
POTENTIAL INSTABILITY WILL GO AHEAD AND OUTLOOK STRONG TO SEVERE
STORMS IN THE HWO FOR SUNDAY AND MONDAY. A SOMEWHAT DRIER LOW LEVEL
AIRMASS IS THEN EXPECTED TO INFILTRATE THE AREA TUESDAY ONWARD THUS
RESULTING IN LOWER POTENTIAL INSTABILITY VALUES. AS A RESULT...WILL
REFRAIN FROM ANY STRONG/SEVERE WEATHER WORDING IN THE HWO TUESDAY
AND BEYOND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 104 AM CDT SAT AUG 10 2013
EASING OFF THE REDUCED VISIBILITY FOR LATE TONIGHT AND EARLY
SATURDAY AS MOST LOCATIONS ARE NOT SHOWING MUCH DECLINE IN
VISIBILITY...AND ALSO...MODEL DATA ARE INDICATING THAT WE WILL NOT
TANK AS BADLY AS ONCE THOUGHT. THERE COULD BE A BIT OF A GUST FOR
SATURDAY AFTERNOON AND DECREASE SOMEWHAT FOR SATURDAY EVENING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HEINLEIN
SHORT TERM...PFANNKUCH
LONG TERM...BRYANT
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS HASTINGS NE
135 AM CDT SAT AUG 10 2013
.UPDATE...
ISSUED AT 941 PM CDT FRI AUG 9 2013
TRIMMED BACK POPS FOR THE TONIGHT PERIOD...MAINLY TO AREAS
CONFINED TO OUR NORTHWESTERN COUNTIES. THESE SHOWERS SHOULD N0T
LAST PAST MIDNIGHT AS MESOSCALE ANALYSIS INDICATES AN INCREASE IN
CAPPING ACROSS AREAS WHERE CURRENT THUNDERSTORM ACTIVITY IS
ONGOING. ALSO TRIMMED BACK THE PATCHY FOG TO ACCOUNT FOR INCREASE
CLOUD COVER ACROSS OUR NORTH...WHICH SHOULD INHIBIT FOG IN THESE
AREAS. THE PATCHY FOG STILL INCLUDES THE TRI-CITIES AND AREAS
SOUTH OF I-80...WITH A TIME FRAME FROM ROUGHLY 08Z TO 13Z THIS
MORNING.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 345 PM CDT FRI AUG 9 2013
THE PRIMARY ISSUES DURING THE NEXT 24 HOURS INVOLVES ISOLATED AND
LIKELY NON-SEVERE SHOWER/STORM DEVELOPMENT INTO THIS
EVENING...AND WHETHER OR NOT ANY IMPACTFUL FOG MIGHT DEVELOP AGAIN
OVERNIGHT. HAVE MAINTAINED A SHOWER/STORM-FREE FORECAST CWA-WIDE
FROM LATE THIS EVENING THROUGH SATURDAY AFTERNOON.
20Z OBJECTIVE SURFACE ANALYSIS REVEALS A VERY SUBTLE...WEAK COLD
FRONT ALIGNED GENERALLY EAST-WEST ACROSS THE HEART OF THE NEB
CWA...ALTHOUGH ONE HAS TO LOOK PRETTY TO FIND IT...AS ALL IT
REALLY DOES IS SEPARATE A LIGHT EAST-NORTHEAST BREEZE FROM A LIGHT
EAST TO EAST-SOUTHEAST ONE. THIS LIGHT FLOW WITH SUSTAINED BREEZES
MOST ALL AREAS NO MORE THAN 5-10 MPH IS A RESULT OF BROAD SURFACE
HIGH PRESSURE OVER THE REGION...WITH THE CORE OF THE PARENT HIGH
AROUND 1027 MILLIBARS CENTERED WELL TO THE NORTH OVER
SASKATCHEWAN. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL
DATA REVEALS RATHER WEAK FLOW ALOFT OVER THE CWA...GENERALLY
WESTERLY UP AT 300MB...NORTHERLY AT 500 MB...AND EVEN FARTHER DOWN
FROM THE EAST-NORTHEAST AT 700MB. ON THE LARGE SCALE...THE CENTRAL
PLAINS LIES IN THE INTERFACE BETWEEN A BROAD TROUGH AND EMBEDDED
VIGOROUS SHORTWAVE TRACKING EAST ACROSS SOUTHEAST CANADA...AND A
RIDGE AXIS EXTENDING EAST-WEST ACROSS THE SOUTHERN CONUS AND THEN
NORTHWARD INTO THE ROCKIES. ON A MORE REGIONAL LEVEL...A LOW-
AMPLITUDE MID LEVEL DISTURBANCE IS LIFTING OUT ACROSS EASTERN
KS/WESTERN MO. OTHER VERY SUBTLE DISTURBANCES APPEAR TO BE
RIPPLING OUT OF THE WY AREA TOWARD WESTERN NEB/SOUTHWEST SD...AND
HELPING TO KICK OFF STORMS IN THE NORTHERN PANHANDLE.
LOCALLY...JUST WITHIN THE PAST HOUR A FEW SMALL...ISOLATED
SHOWERS/POSSIBLY WEAK STORMS HAVE BUBBLED UP OVER DAWSON/BUFFALO
COUNTIES BUT HAVE SHOWED LITTLE SIGN OF MAINTAINING ORGANIZATION.
VISIBLE SATELLITE REVEALS PARTLY TO MOSTLY CLOUDY SKIES OVER THE
CWA AT MID-AFTERNOON...WITH A DECENT LOW LEVEL CUMULUS FIELD
ACROSS MUCH OF THE CENTRAL/WEST...AND SOME LINGERING HIGH CIRRUS
STILL GRADUALLY DEPARTING EASTERN COUNTIES. HIGH TEMPS APPEAR TO
BE FAIRLY WELL ON TRACK...WITH MOST AREAS LIKELY TO END UP IN THE
81-84 RANGE.
GOING FORWARD THROUGH THE LATE AFTERNOON HOURS THROUGH
03Z/10PM...HAVE OPTED TO KEEP THINGS SIMPLE AND ADVERTISE A SLIGHT
CHANCE OF SHOWERS/ISOLATED THUNDERSTORMS CWA-WIDE...ALTHOUGH WOULD
ANTICIPATE THE MOST LIKELY LOCALIZED DEVELOPMENT TO CONTINUE
TARGETING THE WESTERN HALF OF THE NEB CWA...WHERE LATEST MESO-
ANALYSIS INDICATES 0-1KM MLCAPE UP TO AROUND 1500 J/KG...AND WITH
LITTLE IF ANY CINH BUT ALSO VERY LIMITED FORCING FOR ASCENT. WITH
DEEP-LAYER SHEAR AVERAGING NO MORE THAN 15-20KT AND MID LEVEL
LAPSE RATES RATHER SHALLOW AT ONLY 5-6 C/KM...THE THREAT FOR
STRONG TO SEVERE STORMS APPEARS TO BE QUITE LIMITED IF NOT NON-
EXISTENT. POST-03Z/10PM...WILL AIM FOR A DRY REST OF THE
NIGHT...AS ANY DIURNAL SUPPORT FOR CONVECTION FROM AFTERNOON
HEATING WILL BE ON THE WANE...AND GIVEN THAT THE MAIN TRACK OF LOW
AMPLITUDE MID LEVEL DISTURBANCES OVERNIGHT SHOULD GENERALLY TARGET
THE NEB/SD BORDER AREA. FURTHERMORE...THE NOSE OF A MODEST 35KT
850MB LOW LEVEL JET CLEARLY AIMS INTO SOUTHERN SD/FAR NORTH CENTRAL
NEB OVERNIGHT...WHICH IS WHERE MOST MODELS INCLUDING THE NAM AND
4M WRF-NMM FOCUS CONVECTION. THAT BEING SAID...WILL HAVE TO KEEP
AN EYE ON THE NORTHWEST CWA AS THE LATEST HRRR MAINTAINS SOME
SANDHILLS CONVECTION WITHIN 50 MILES OF THE CWA THROUGH AROUND
MIDNIGHT...BUT FEEL THIS MAY BE A BIT CLOSER TO HOME THAN IT
ACTUALLY WILL BE. AT THE SURFACE TONIGHT...BREEZES WILL REMAIN
QUITE LIGHT AND AVERAGE UNDER 5 MPH...WHILE GRADUALLY TURNING TO A
SOUTHERLY DIRECTION. GIVEN THE LIGHT WIND SETUP...THERE IS AT
LEAST SOME CONCERN THAT FOG COULD AGAIN DEVELOP AND REDUCE
VISIBILITY TO 1 MILE OR LESS. HOWEVER...THE CONSENSUS OF
MODELS/GUIDANCE IS THAT TONIGHT/S FOG EVENT SHOULDN/T BE AS
DENSE/IMPACTFUL...POSSIBLY DUE TO SLIGHTLY BETTER BETTER MIXING
JUST ABOVE THE SURFACE. FOR NOW...WILL MAINTAIN THE GENERIC PATCHY
FOG MENTION CWA-WIDE FOR THE LATE NIGHT/EARLY MORNING HOURS
INTRODUCED BY THE PREVIOUS SHIFT...BUT WILL DEFER TO THE NEXT FEW
SHIFTS TO POTENTIALLY RAMP UP THIS FOG WORDING IF NEED BE. AS FOR
LOW TEMPS...ACTUALLY NUDGED DOWN 1-2 DEGREES FROM PREVIOUS IN MOST
SPOTS PER A GUIDANCE BLEND...WHICH PUTS MOST AREAS DOWN BETWEEN
57-61 DEGREES.
TURNING TO THE SATURDAY DAYTIME PERIOD 12Z-00Z/7AM-7PM...MAINTAINED
A RAIN-FREE FORECAST CWA-WIDE. IN THE MID/UPPER LEVELS...FAIRLY
WEAK TO MODEST WEST-NORTHWEST FLOW WILL MAINTAIN OVER THE CENTRAL
PLAINS AT/ABOVE 500MB...AND THERE SHOULD BE SOME SUBTLE HEIGHT
RISES AS WELL...AS THE SOUTHERN PLAINS/SOUTHERN ROCKIES RIDGE
EDGES NORTH JUST A BIT. THE PRIMARY MID LEVEL SHORTWAVE TROUGH
TRACK DURING THE DAY WILL BE FROM SD TOWARD SOUTHWEST MN/NORTHWEST
IA...AND THIS DISTURBANCE SHOULD TEAM WITH AN EAST-WEST QUASI-
STATIONARY FRONT SETTING UP NEAR THE NEB/SD BORDER TO FOCUS THE
VAST MAJORITY OF DAYTIME CONVECTION AT LEAST 50-100 MILES NORTH
AND POSSIBLY NORTHWEST OF THE CWA. THE ODDS OF CONVECTION FORMING
LOCALLY WITH DAYTIME HEATING SEEMS SMALLER THAN TODAY GIVEN
SLIGHTLY WARMER TEMPS EVIDENT AT 700MB...DESPITE MODEST MLCAPE
VALUES CLIMBING INTO THE 500-1000 J/KG RANGE PER THE 18Z NAM.
MODEL FORECASTS SOUNDINGS ALSO CLEARLY SHOW A WEAK BUT EVIDENT CAP.
OTHERWISE...ALTHOUGH BY NO MEANS WINDY...THE LATE MORNING-
AFTERNOON HOURS SHOULD FEATURE SOME OF THE MOST NOTICEABLE MODEST
BREEZES FELT IN MOST OF THE CWA IN SEVERAL DAYS...AS A TIGHTENED
PRESSURE GRADIENT TO THE EAST OF HIGH PLAINS LEE TROUGH SHOULD
PROMOTE SUSTAINED SOUTHERLY SPEEDS 10-15 MPH MOST AREAS. GIVEN THE
SOUTHERLY BREEZES...SLIGHTLY WARMER TEMPS AT 850MB...AND LIKELY NO
WORSE THAN PARTLY CLOUDY SKIES...SEE LITTLE REASON WHY HIGH TEMPS
SHOULDN/T BE AT LEAST A TOUCH HIGHER THAN TODAY. AS A
RESULT...NUDGED UP PREVIOUS HIGHS 1-2 DEGREES IN MOST AREAS...WITH
MOST OF THE CWA AIMED FOR FAIRLY UNIFORM HIGHS BETWEEN 83-86
DEGREES.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 344 PM CDT FRI AUG 9 2013
GUIDANCE SUGGESTS QUASI-ZONAL TO NORTHWESTERLY MID TO UPPER LEVEL
FLOW WILL PERSIST OVER THE CENTRAL PLAINS THROUGH MUCH OF THE LONG
TERM FORECAST PERIOD...WITH THE POSSIBILITY OF MULTIPLE MID LEVEL
PERTURBATIONS MOVING OVER THE AREA. PRECIPITATION CHANCES REMAIN
INTACT THROUGHOUT THE LONG TERM FORECAST PERIOD AS A RESULT.
STARTING SATURDAY NIGHT...THERE ARE SIGNS...PRIMARILY FROM THE
EC...OPERATIONAL GFS AND SREF-MEAN...THAT CENTRAL TO NORTHERN HIGH
PLAINS CONVECTION FROM SATURDAY AFTERNOON/EVENING MAY HOLD TOGETHER
LONG ENOUGH...PRIMARILY DUE TO LOW LEVEL THERMAL ADVECTION ALONG THE
AXIS OF A ~30KT 850MB JET STREAK...TO IMPACT NORTHERN PORTIONS OF
OUR CWA. CONFIDENCE IS NOT OVERLY HIGH THAT MEASURABLE PRECIPITATION
WILL BE REALIZED ACROSS OUR AREA SATURDAY NIGHT AND AS A
RESULT...POPS ONLY IN THE 20-30% RANGE CURRENTLY EXIST. HEADING INTO
THE DAY SUNDAY...LOW LEVEL CONVERGENCE ALONG A LOW LEVEL BAROCLINIC
ZONE/TROUGH COULD PROMOTE ENOUGH LIFT...ALONG WITH A PASSING MID
LEVEL PERTURBATION...TO PROMOTE PRECIPITATION PRODUCTION ACROSS
PORTIONS OF THE REGION. WHERE EXACTLY THE BOUNDARY POSITIONS ITSELF
IS THE BIGGEST QUESTION AT THIS TIME. THE NAM...EC...AND SREF-MEAN
ALL SUGGEST THE BOUNDARY WILL MOVE INTO NORTHERN OR CENTRAL PORTIONS
OF OUR CWA...WHILE THE OPERATIONAL GFS KEEPS THE BOUNDARY TO THE NORTH OF
OUR AREA. GIVEN THE UNCERTAINTY WITH RESPECT TO BOUNDARY
LOCATION...WENT NO HIGHER THAN 20-30% FOR THE DAY SUNDAY. CHANCES
FOR PRECIPITATION...ALBEIT LOW CHANCES DUE TO LOW CONFIDENCE...THEN
CONTINUE ACROSS MUCH OF OUR AREA SUNDAY NIGHT AS THE AXIS OF A
25-30KT 850MB JET STREAK DEVELOPS AND YET ANOTHER MID LEVEL
PERTURBATION POTENTIALLY MOVES OVER PORTIONS OF THE REGION. 20-30%
POPS REMAIN INTACT ACROSS THE AREA SUNDAY NIGHT AS A RESULT.
FINALLY...DURING THE DAY MONDAY...YET ANOTHER WEAK MID LEVEL
PERTURBATION MAY MOVE OVER THE AREA. CONFIDENCE IS LOW WITH RESPECT
TO ANY ONE LOCATION ACROSS THE AREA RECEIVING MEASURABLE
PRECIPITATION BUT RATHER THAN ELIMINATE POPS...WENT AHEAD AND
PRESENTED MOSTLY ~20% POPS TO MUCH OF OUR AREA FOR MONDAY.
MID LEVEL PERTURBATIONS MOVING OVER THE AREA WILL ALSO PROMOTE
CHANCES FOR PRECIPITATION ACROSS OUR AREA MONDAY NIGHT ONWARD AND AS
A RESULT...ALLBLEND PRESENTED POPS RANGING ANYWHERE FROM 20% TO 50%.
AFTER COORDINATION WITH SURROUNDING OFFICES...A FEW MINOR TWEAKS
WERE MADE TO TUESDAY POPS. OTHERWISE...ALLBLEND POPS WERE LEFT
UNCHANGED FOR THE MOST PART DUE TO THE LOW PROBABILITY OF IMPROVING
ON THE ALLBLEND SOLUTION.
DECENT LOW LEVEL MOISTURE...WITH SURFACE DEWPOINTS IN THE UPPER 60S
TO NEAR 70...WILL HELP PROMOTE RESPECTABLE LEVELS OF POTENTIAL
INSTABILITY BOTH SUNDAY AND MONDAY...WITH THE NAM AND OPERATIONAL GFS
BOTH SUGGESTING MUCAPE VALUES IN THE 2500-3500J/KG RANGE. DEEP LAYER
BULK SHEAR DOES NOT APPEAR AS THOUGH IT WILL BE OVERLY
IMPRESSIVE...GENERALLY IN THE 20-25KT RANGE...BUT GIVEN THE EXPECTED
POTENTIAL INSTABILITY WILL GO AHEAD AND OUTLOOK STRONG TO SEVERE
STORMS IN THE HWO FOR SUNDAY AND MONDAY. A SOMEWHAT DRIER LOW LEVEL
AIRMASS IS THEN EXPECTED TO INFILTRATE THE AREA TUESDAY ONWARD THUS
RESULTING IN LOWER POTENTIAL INSTABILITY VALUES. AS A RESULT...WILL
REFRAIN FROM ANY STRONG/SEVERE WEATHER WORDING IN THE HWO TUESDAY
AND BEYOND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 104 AM CDT SAT AUG 10 2013
EASING OFF THE REDUCED VISIBILITY FOR LATE TONIGHT AND EARLY
SATURDAY AS MOST LOCATIONS ARE NOT SHOWING MUCH DECLINE IN
VISIBILITY...AND ALSO...MODEL DATA ARE INDICATING THAT WE WILL NOT
TANK AS BADLY AS ONCE THOUGHT. THERE COULD BE A BIT OF A GUST FOR
SATURDAY AFTERNOON AND DECREASE SOMEWHAT FOR SATURDAY EVENING.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...GUERRERO
SHORT TERM...PFANNKUCH
LONG TERM...BRYANT
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1022 PM EDT SUN AUG 11 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH THIS EVENING. A
STORM SYSTEM AND ASSOCIATED COLD FRONT WILL APPROACH THE NORTH
COUNTRY LATE MONDAY AFTERNOON WITH SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED INTO TUESDAY. THE FRONT WILL SLOWLY PUSH
EASTWARD TUESDAY NIGHT USHERING IN A COOL AND DRY CANADIAN
AIR MASS. TEMPERATURES THROUGH THE REST OF THE WORKWEEK WILL BE A
FEW DEGREES BELOW NORMAL FOR MID-AUGUST.
&&
.NEAR TERM /UNTIL 7 AM MONDAY MORNING/...
AS OF 1022 PM EDT SUNDAY...UPDATE ISSUED TO ADJUST CLD COVER OVER
NORTHERN PORTIONS OF THE CWA. LATEST SATELLITE TRENDS SHOW THE MID
CLD DECK MVG FAIRLY PROGRESSIVELY AND SHOULD LEAN THE CWA TOWARDS
CLRING CONDITIONS IN THE NEXT COUPLE HRS. W/ THIS CLRING...EXPECTING
TEMPS TO FALL IN LINE WITH RADIATIONAL COOLING EFFECTS TAKING
PLACE.
LATE-AFTERNOON VISIBLE SATELLITE TRENDS SHOW DIURNALLY-DRIVEN FAIR
WEATHER STRATOCUMULUS QUICKLY ERODING. LOOKING UPSTREAM
HOWEVER...A BROAD SWATH OF BROKEN TO OVERCAST 4000-6000 FT
CEILINGS IS QUICKLY MOVING INTO WESTERN NEW YORK AND THE NORTHERN
SHORE OF LAKE ONTARIO. THESE CLOUDS ARE EMBEDDED IN FAST ZONAL
FLOW ALOFT /40-50KTS AT 500 MB PER RAP MODEL ANALYSES/. THESE WILL
MOVE WEST-TO- EAST OVER THE SOUTHERN SAINT LAWRENCE
VALLEY...NORTHERN ADIRONDACKS...AND INTO SOUTHERN VERMONT THROUGH
MIDNIGHT. SO I HAVE INCREASED CLOUD COVER THROUGH MIDNIGHT IN
THESE AREAS...THOUGH QUICKLY CLEARING AS PER SATELLITE TRENDS
ACROSS THE NORTHERN LAKES. I ALSO ADJUSTED LOW TEMPERATURES UP A
DEGREE OR SO GIVEN THE GREATER COVERAGE IN CLOUDS. ASIDE FROM
THESE MINOR ADJUSTMENTS THE GOING FORECAST LOOKS GOOD AT THIS
POINT WITH NO OTHER CHANGES MADE.
&&
.SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 337 PM EDT SUNDAY...INCREASING CLOUDS EXPECTED ON MONDAY
AHEAD OF AN APPROACHING UPPER LEVEL TROUGH MOVING SOUTHEASTWARD
OUT OF NORTHERN ONTARIO. ITS ASSOCIATED SFC COLD FRONT WILL BE
SLOW TO MOVE SOUTHEASTWARD WITH 500 MB FLOW BEING NEARLY PARALLEL
TO THE SFC FRONT. SO HAVE SLOWED THE ONSET OF SLIGHT CHANCE
PRECIPITATION PROBABILITIES INTO THE SAINT LAWRENCE VALLEY UNTIL
AFTER 18Z MONDAY WITH THAT IDEA IN MIND...AND A SLOW EASTWARD
INCREASE THROUGH THE EVENING UP TO HIGH CHANCE/LOW LIKELY BY 12Z
TUESDAY. HIGHS MONDAY IN THE 70S WITH A FEW LOW 80S POSSIBLE IN
THE CHAMPLAIN VALLEY & LOWS IN THE 50S TO LOW 60S.
THE FRONT WILL BE SLOWLY PUSHING SOUTHEASTWARD ACROSS THE REGION ON
TUESDAY. THINK THAT THUNDER IS POSSIBLE BUT MAINLY FROM THE
CHAMPLAIN VALLEY SOUTH AND EAST. IN FACT THE COMBINATION OF
STRONGEST DYNAMICS AS WELL AS SOME MODEST INSTABILITY /CAPE VALUES
800-1000 J/KG/ SUGGESTS THE BEST CHANCE FOR THUNDER WILL BE ACROSS
CENTRAL AND SOUTHERN VERMONT. WHILE LIKELY POPS ARE INDICATED FOR
MOST OF THE AREA ON TUESDAY...HAVE INCLUDED CHANCE THUNDER FOR
CENTRAL AND SOUTHERN VERMONT WITH SLIGHT CHANCE THUNDER FOR THE REST
OF VERMONT FOR TUESDAY AFTERNOON. FRONT LOOKS TO PUSH THROUGH THE
AREA AFTER 00Z WEDNESDAY WITH SOME LINGERING SHOWERS UNTIL THE FRONT
CLEARS FOR EASTERN VERMONT. GENERALLY THINK IT`S A LIGHT TO MODERATE
QPF EVENT WITH 36 HR QPF TOTALS FROM .25" TO .50".
STRONG COLD AIR ADVECTION BEHIND THE FRONT ON TUESDAY NIGHT WITH 850
TEMPERATURES DROPPING TO +4C TO +6C SHOULD ALLOW FOR LOW
TEMPERATURES TO DROP INTO THE 40S TO LOW 50S. DUE TO SOME QUESTION
AS TO HOW MUCH CLOUD COVER WILL BE LEFT OVER HAVE OPTED TO LEAN
SLIGHTLY WARMER. IF SKIES CAN CLEAR OUT FURTHER IT MAY BE A FEW
DEGREES COOLER THAN SHOWN HOWEVER.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 337 PM EDT SUNDAY...NORTHWEST FLOW ALOFT DEVELOPS ON
BACKSIDE OF UPPER TROUGH ON WEDNESDAY. DRIER WEATHER IS
EXPECTED...BUT COLD AIR ADVECTION WILL RESULT IN HIGH TEMPERATURES
BEING SEVERAL DEGREES BELOW NORMAL. UPPER TROUGH TO PERSIST OVER
EASTERN CANADA THURSDAY AND FRIDAY FOR A CONTINUATION OF THE DRY
WEATHER WITH SLOWLY MODERATING TEMPERATURES...BUT VALUES WILL
STILL BE SLIGHTLY BELOW NORMAL. EVENTUALLY THE FLOW ALOFT BACKS TO
THE WEST AND SOUTHWEST OVER THE WEEKEND...SO THE WARMING TREND
WILL CONTINUE TO APPROACH SEASONAL LEVELS. DRY WEATHER WILL
CONTINUE TO BE THE RULE. IF THERE IS ANY CHANCE FOR SHOWERS...A
SMALL CHANCE AT BEST...IT WOULD BE ON FRIDAY AS A WEAK FRONT DROPS
DOWN INTO THE AREA FROM THE NORTH.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
THROUGH 00Z TUESDAY...STILL LOOKING AT VFR CONDITIONS THROUGH MOST
OF THE PERIOD. THE ONLY EXCEPTION TO THIS WILL BE A PERIOD OF IFR
TO VLIFR CONDITIONS AT KSLK AND KMPV BETWEEN 07Z AND 12Z. THE MOST
CONCENTRATED PERIOD FOR CLOUDS WILL BE THROUGH ABOUT 07Z TONIGHT
WHEN AN AREA OF MID LEVEL CLOUDS MOVE ACROSS NORTHERN NEW YORK AND
VERMONT. OTHERWISE...WINDS WILL BE VARIABLE AT SPEEDS UNDER 10
KNOTS THROUGH MUCH OF THE PERIOD.
OUTLOOK 00Z TUESDAY THROUGH FRIDAY...
MVFR CONDITIONS EXPECTED DUE TO CLOUDS AND SHOWERS LATE MONDAY
NIGHT INTO TUESDAY...THEN VFR CONDITIONS THROUGH THE REMAINDER OF
THE PERIOD.
&&
.EQUIPMENT...
AS OF 337 PM EDT SUNDAY...NOAA WEATHER RADIO STATION WXM 44...
BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF
THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...LOCONTO
NEAR TERM...JN/LOCONTO
SHORT TERM...LOCONTO
LONG TERM...EVENSON
AVIATION...EVENSON
EQUIPMENT...JN
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
746 PM EDT SUN AUG 11 2013
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH THIS EVENING. A
STORM SYSTEM AND ASSOCIATED COLD FRONT WILL APPROACH THE NORTH
COUNTRY LATE MONDAY AFTERNOON WITH SCATTERED SHOWERS AND
THUNDERSTORMS EXPECTED INTO TUESDAY. THE FRONT WILL SLOWLY PUSH
EASTWARD TUESDAY NIGHT USHERING IN A COOL AND DRY CANADIAN
AIR MASS. TEMPERATURES THROUGH THE REST OF THE WORKWEEK WILL BE A
FEW DEGREES BELOW NORMAL FOR MID-AUGUST.
&&
.NEAR TERM /UNTIL 7 AM MONDAY MORNING/...
AS OF 641 PM EDT SUNDAY...LATE-AFTERNOON VISIBLE SATELLITE TRENDS
SHOW DIURNALLY-DRIVEN FAIR WEATHER STRATOCUMULUS QUICKLY ERODING.
LOOKING UPSTREAM HOWEVER...A BROAD SWATH OF BROKEN TO OVERCAST
4000-6000 FT CEILINGS IS QUICKLY MOVING INTO WESTERN NEW YORK AND
THE NORTHERN SHORE OF LAKE ONTARIO. THESE CLOUDS ARE EMBEDDED IN
FAST ZONAL FLOW ALOFT /40-50KTS AT 500 MB PER RAP MODEL ANALYSES/.
THESE WILL MOVE WEST-TO- EAST OVER THE SOUTHERN SAINT LAWRENCE
VALLEY...NORTHERN ADIRONDACKS...AND INTO SOUTHERN VERMONT THROUGH
MIDNIGHT. SO I HAVE INCREASED CLOUD COVER THROUGH MIDNIGHT IN
THESE AREAS...THOUGH QUICKLY CLEARING AS PER SATELLITE TRENDS
ACROSS THE NORTHERN LAKES. I ALSO ADJUSTED LOW TEMPERATURES UP A
DEGREE OR SO GIVEN THE GREATER COVERAGE IN CLOUDS. ASIDE FROM
THESE MINOR ADJUSTMENTS THE GOING FORECAST LOOKS GOOD AT THIS
POINT WITH NO OTHER CHANGES MADE.
&&
.SHORT TERM /7 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 337 PM EDT SUNDAY...INCREASING CLOUDS EXPECTED ON MONDAY
AHEAD OF AN APPROACHING UPPER LEVEL TROUGH MOVING SOUTHEASTWARD
OUT OF NORTHERN ONTARIO. ITS ASSOCIATED SFC COLD FRONT WILL BE
SLOW TO MOVE SOUTHEASTWARD WITH 500 MB FLOW BEING NEARLY PARALLEL
TO THE SFC FRONT. SO HAVE SLOWED THE ONSET OF SLIGHT CHANCE
PRECIPITATION PROBABILITIES INTO THE SAINT LAWRENCE VALLEY UNTIL
AFTER 18Z MONDAY WITH THAT IDEA IN MIND...AND A SLOW EASTWARD
INCREASE THROUGH THE EVENING UP TO HIGH CHANCE/LOW LIKELY BY 12Z
TUESDAY. HIGHS MONDAY IN THE 70S WITH A FEW LOW 80S POSSIBLE IN
THE CHAMPLAIN VALLEY & LOWS IN THE 50S TO LOW 60S.
THE FRONT WILL BE SLOWLY PUSHING SOUTHEASTWARD ACROSS THE REGION ON
TUESDAY. THINK THAT THUNDER IS POSSIBLE BUT MAINLY FROM THE
CHAMPLAIN VALLEY SOUTH AND EAST. IN FACT THE COMBINATION OF
STRONGEST DYNAMICS AS WELL AS SOME MODEST INSTABILITY /CAPE VALUES
800-1000 J/KG/ SUGGESTS THE BEST CHANCE FOR THUNDER WILL BE ACROSS
CENTRAL AND SOUTHERN VERMONT. WHILE LIKELY POPS ARE INDICATED FOR
MOST OF THE AREA ON TUESDAY...HAVE INCLUDED CHANCE THUNDER FOR
CENTRAL AND SOUTHERN VERMONT WITH SLIGHT CHANCE THUNDER FOR THE REST
OF VERMONT FOR TUESDAY AFTERNOON. FRONT LOOKS TO PUSH THROUGH THE
AREA AFTER 00Z WEDNESDAY WITH SOME LINGERING SHOWERS UNTIL THE FRONT
CLEARS FOR EASTERN VERMONT. GENERALLY THINK IT`S A LIGHT TO MODERATE
QPF EVENT WITH 36 HR QPF TOTALS FROM .25" TO .50".
STRONG COLD AIR ADVECTION BEHIND THE FRONT ON TUESDAY NIGHT WITH 850
TEMPERATURES DROPPING TO +4C TO +6C SHOULD ALLOW FOR LOW
TEMPERATURES TO DROP INTO THE 40S TO LOW 50S. DUE TO SOME QUESTION
AS TO HOW MUCH CLOUD COVER WILL BE LEFT OVER HAVE OPTED TO LEAN
SLIGHTLY WARMER. IF SKIES CAN CLEAR OUT FURTHER IT MAY BE A FEW
DEGREES COOLER THAN SHOWN HOWEVER.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 337 PM EDT SUNDAY...NORTHWEST FLOW ALOFT DEVELOPS ON
BACKSIDE OF UPPER TROUGH ON WEDNESDAY. DRIER WEATHER IS
EXPECTED...BUT COLD AIR ADVECTION WILL RESULT IN HIGH TEMPERATURES
BEING SEVERAL DEGREES BELOW NORMAL. UPPER TROUGH TO PERSIST OVER
EASTERN CANADA THURSDAY AND FRIDAY FOR A CONTINUATION OF THE DRY
WEATHER WITH SLOWLY MODERATING TEMPERATURES...BUT VALUES WILL
STILL BE SLIGHTLY BELOW NORMAL. EVENTUALLY THE FLOW ALOFT BACKS TO
THE WEST AND SOUTHWEST OVER THE WEEKEND...SO THE WARMING TREND
WILL CONTINUE TO APPROACH SEASONAL LEVELS. DRY WEATHER WILL
CONTINUE TO BE THE RULE. IF THERE IS ANY CHANCE FOR SHOWERS...A
SMALL CHANCE AT BEST...IT WOULD BE ON FRIDAY AS A WEAK FRONT DROPS
DOWN INTO THE AREA FROM THE NORTH.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
THROUGH 00Z TUESDAY...STILL LOOKING AT VFR CONDITIONS THROUGH MOST
OF THE PERIOD. THE ONLY EXCEPTION TO THIS WILL BE A PERIOD OF IFR
TO VLIFR CONDITIONS AT KSLK AND KMPV BETWEEN 07Z AND 12Z. THE MOST
CONCENTRATED PERIOD FOR CLOUDS WILL BE THROUGH ABOUT 07Z TONIGHT
WHEN AN AREA OF MID LEVEL CLOUDS MOVE ACROSS NORTHERN NEW YORK AND
VERMONT. OTHERWISE...WINDS WILL BE VARIABLE AT SPEEDS UNDER 10
KNOTS THROUGH MUCH OF THE PERIOD.
OUTLOOK 00Z TUESDAY THROUGH FRIDAY...
MVFR CONDITIONS EXPECTED DUE TO CLOUDS AND SHOWERS LATE MONDAY
NIGHT INTO TUESDAY...THEN VFR CONDITIONS THROUGH THE REMAINDER OF
THE PERIOD.
&&
.EQUIPMENT...
AS OF 337 PM EDT SUNDAY...NOAA WEATHER RADIO STATION WXM 44...
BROADCASTING FROM THE TOP OF MOUNT ASCUTNEY VERMONT...REMAINS OFF
THE AIR UNTIL FURTHER NOTICE DUE TO A DAMAGED ANTENNA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.
&&
$$
SYNOPSIS...LOCONTO
NEAR TERM...LOCONTO
SHORT TERM...LOCONTO
LONG TERM...EVENSON
AVIATION...EVENSON
EQUIPMENT...WFO BTV
AREA FORECAST DISCUSSION
NWS RALEIGH NC
810 PM EDT SUN AUG 11 2013
.SYNOPSIS...
A SURFACE TROUGH WILL LINGER OVER THE CAROLINAS AND MIDDLE ATLANTIC
REGION THROUGH TUESDAY. A COLD FRONT WILL THEN CROSS OUR AREA
TUESDAY NIGHT...AND REMAIN STALLED ALONG THE COAST THROUGH THE REST
OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SUNDAY...
THE PATTERN WILL REMAIN RATHER PERSISTENT THROUGH THE NEAR TERM...
WITH ADDITIONAL SHOWERS AND THUNDERSTORMS EXPECTED THIS AFTERNOON
AND EVENING. REGIONAL RADAR SHOWS SHOWERS AND THUNDERSTORMS JUST TO
OUR WEST ACROSS THE FOOTHILLS...AND THESE ARE EXPECTED TO CONTINUE
MOVING EAST WITH NEW DEVELOPMENT EASTWARD ON OUTFLOW BOUNDARIES.
ALSO NOTED A WEAK/SHEARED SHORT WAVE EMBEDDED IN THE MID LEVEL FLOW
CURRENTLY MOVING ACROSS THE MOUNTAINS. THIS FEATURE MAY PROVIDE SOME
ADDITIONAL SUPPORT FOR THE ONGOING ACTIVITY. LATEST OBSERVED
CONVECTIVE PARAMETERS ARE SIMILAR TO YESTERDAY...SO IN TERMS OF
IMPACTS...TODAYS THUNDERSTORMS WILL ONCE AGAIN BE CAPABLE OF MAINLY
BRIEF INTENSE DOWNPOURS AND FREQUENT TO EXCESSIVE-AT-TIMES CG
LIGHTNING. STILL CAN`T RULE OUT A COUPLE ISOLATED DAMAGING WIND
GUSTS...ALTHOUGH ITS WORTH NOTING THAT THE LATEST DCAPE VALUES
ACROSS ALL OF CENTRAL NC ARE BELOW 600 J/KG...WITH THE RAP SHOWING
LITTLE INCREASE THROUGH THE AFTERNOON.
ACTIVITY SHOULD WIND DOWN BY MIDNIGHT...WITH PC SKIES THE REST OF
THE NIGHT AND SOME PATCHY FOG...PARTICULARLY NEAR AREAS THAT RECEIVE
HEAVIER RAIN THIS AFTERNOON. LOWS TONIGHT WILL BE SIMILAR TO PREV
NIGHTS...LOWER 70S.
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 200 PM SUNDAY...
IN THE BIG PICTURE...THE L/W TROUGH OVER NE NORTH AMERICA WILL BEGIN
TO DEEPEN SOUTHWARD AS A S/W TROUGH EMBEDDED WITHIN THE L/W TROUGH
MOVES SOUTH ACROSS THE GREAT LAKES. FOR OUR AREA...FORECAST
SOUNDINGS SHOW SUBTLE DRYING IN THE WAKE OF THE OF THE WEAK S/W
TROUGH THAT WILL CROSS OUR AREA LATER TODAY. HOWEVER...WITH PWAT
STILL PROGGED TO REMAIN AT OR SLIGHTLY ABOVE 1.75 INCHES...LITTLE
OVERALL CHANGE IN THE CONVECTIVE PARAMETERS FROM TODAY...AND THE
PIEDMONT TROUGH PROVIDING LOW LEVEL SUPPORT...LOOK FOR ADDITIONAL
SCATTERED AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS...
WITH THE MAIN IMPACTS ONCE AGAIN BEING DOWNPOURS...CG LIGHTNING...
AND PERHAPS AN ISOLD DAMAGING WIND GUST OR TWO. ITS WORTH NOTING
THAT MOST CAMS SHOW LESS COVERAGE OF THIS ACTIVITY COMPARED TO
TODAY...PERHAPS A RESULT OF THE SUBTLE DRYING AND LIMITED LARGE
SCALE SUPPORT. GIVEN SLIGHTLY LOWER HEIGHTS AND SUBSEQUENT THICKNESS
VALUES...HIGHS ON MONDAY SHOULD BE A DEGREE TO TWO LOWER THAN
TODAY...STILL AROUND 90 FOR MOST PLACES ALONG WITH PLENTY OF
HUMIDITY. THE HIGHEST HEAT INDEX VALUES IN OUR CWA WILL BE IN THE
UPPER 90S ACROSS OUR SE ZONES WHERE SFC DWPTS WILL BE THE HIGHEST.
MONDAY NIGHT...A WEAK S/W TROUGH IN THE SW FLOW IS PROGGED TO MOVE
ACROSS THE MID ATLANTIC REGION. THE SYNOPTIC SCALE MODELS ARE MORE
AGGRESSIVE WITH PRECIP/QPF AS A RESULT OF THIS SYSTEM...WHILE MANY
OF THE CAMS ARE LESS ENTHUSIASTIC FOR MUCH PRECIP ACROSS OUR AREA...
LIKELY THE RESULT OF LOSS OF DAYTIME HEATING. SINCE THERE WILL BE
SOME SYNOPTIC FORCING IN THE AREA...PREFER TO KEEP AT LEAST A SLIGHT
CHANCE POP ACROSS OUR ZONES DURING THIS TIME. LOWS ONCE AGAIN IN THE
LOWER 70S.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 200 PM SUNDAY...
THE LONG TERM FORECAST IS STILL ON TRACK FOR A VERY WET PERIOD FROM
TUESDAY THROUGH SUNDAY WITH A FRONTAL ZONE STALLING OUT OVER THE
AREA AS MULTIPLE SHORTWAVES PROGRESS ALONG IT. 6Z GEFS ANOMALIES
SHOW PRECIPITABLE WATER VALUES 2-3 STANDARD DEVIATIONS ABOVE NORMAL
IN THE SOUTHERN PORTION OF THE AREA WITH RAW VALUES OF 2-2.5 INCHES
THROUGH MUCH OF THE LONG TERM. COMPETING FOR NOTORIETY WILL BE HIGH
TEMPERATURES...THURSDAY IN PARTICULAR...WHEN HIGHS IN THE TRIAD
COULD BE ONLY IN THE LOW TO MID 70S. BOTH THE ECMWF AND GFS ARE
SHOWING THICKNESS VALUES IN THE HIGH 1360S WHICH CORRESPONDS TO
NORMAL VALUES FOR EARLY MAY...NOT EARLY AUGUST. THE LARGEST SEVERE
THREAT DURING THIS PERIOD WILL BE FLOODING AS WPC IS STILL SHOWING 7
DAY TOTALS 2.5-3 INCHES IN THE TRIAD...3-4 INCHES IN THE
TRIANGLE...AND 5 PLUS ON THE COAST.
FOR TUESDAY THE FRONT IS PROGGED TO SET UP OVER UPSTATE SOUTH
CAROLINA AND THE COASTAL PLAIN OF NORTH CAROLINA. FORECAST SOUNDINGS
IN BUFKIT SHOW A SETUP SIMILAR TO THE LAST COUPLE OF DAYS WITH GOOD
INSTABILITY ALONG WITH MODERATE SHEAR VALUES...LEADING TO MOST
LIKELY MULTICELLULAR OR BROKEN LINE TYPE CONVECTION. BY
WEDNESDAY...WITH THE FRONTAL STILL PARKED TO THE SOUTH...THE SURFACE
HIGH BEGINS TO MOVE EASTWARD...BEGINNING TO DEVELOP THE WEDGE AS.
INSTABILITY CRASHES BUT SHEAR INCREASES TO 40-50 KNOTS. SOUNDINGS
BECOME VERY SATURATED IN THE LOW LEVELS AS WARM RAIN PROCESSES
BECOME DOMINANT. ANAFRONTAL RAIN WILL SPREAD NORTHWARD THROUGH NC
AND INTO SOUTHERN VA BY WEDNESDAY EVENING. SURFACE TEMPERATURES WILL
COOL IN RESPONSE TO CLOUD COVER AND THE NORTHEASTERLY SURFACE WINDS
BROUGHT ON BY THE FORMATION OF THE WEDGE FRONT. THIS GENERAL PATTERN
CONTINUES THROUGH THE DAY ON THURSDAY. AN ADDED PUNCH TO THE
RAINFALL TOTALS ON THURSDAY COULD BE PROVIDED BY A MESO-LOW MOVING
UP FROM GEORGIA THROUGH SOUTH CAROLINA AND INTO OUR CWA FROM THE
SOUTHWEST.
ON FRIDAY...THE SOUNDINGS DRY OUT A LITTLE BIT...AS THE MESO-LOW
EXITS TO THE NORTHEAST...TAKING A LOT OF MOISTURE WITH IT. A SMALL
SURFACE HIGH TRIES TO FORM OVER THE CAROLINAS AND MID-LEVEL DRY AIR
WILL EVENTUALLY WORK DOWN TO THE SURFACE ALTHOUGH SUFFICIENT MID AND
UPPER LEVEL SATURATION WILL KEEP IT CLOUDY THROUGH SATURDAY NIGHT.
PRECIPITATION CHANCES WILL BE BEST ALONG THE COAST AS AN INVERTED
TROUGH SETS UP OVER THE COAST. MUCH FURTHER SOUTH IN THE GULF OF
MEXICO...THE GFS SPINS UP A TROPICAL SYSTEM WHICH HEADS FOR MOBILE
BAY...BUT THIS FEATURE HAS NOT YET APPEARED IN THE ECMWF.
LOW LEVEL MOISTENING BEGINS AGAIN ON SUNDAY WITH THE RETURN OF
RAILROAD TRACK SOUNDINGS AND AT LEAST SOME LOW LEVEL INSTABILITY
AHEAD OF WHAT MAY OR MAY NOT BE A TROPICAL SYSTEM MOVING INTO
ALABAMA. REGARDLESS OF WHAT IT IS...THE LOW PRESSURE SYSTEM COUPLED
WITH THE HIGH OFF THE COAST WILL FUNNEL EVEN MORE MOISTURE INTO THE
CAROLINAS FOR SUNDAY AND BEYOND INTO THE WORK WEEK.
TEMPERATURES WILL SHOW A COOLING TREND EARLY IN THE LONG TERM WITH
UPPER 80S ON TUESDAY CRASHING TO THE LOW 80S BY WEDNESDAY AND DOWN
INTO THE MID TO UPPER 70S...AT LEAST IN THE NW...THURSDAY AND FRIDAY
BEFORE REBOUNDING BACK INTO THE LOW 80S IN MOST PLACES BY SUNDAY.
EXPECT LOWS IN THE UPPER 60S TO LOW 70S EARLY ON FOLLOWED BY LOW TO
MID 60S LATE IN THE PERIOD.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 805 PM SUNDAY...
ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON/EVENING HAVE MANAGED TO
MISS THE CENTRAL NC TAF SITES. WITH THE LOSS OF DAYTIME HEATING AND
RESULTANT DWINDLING COVERAGE AND INTENSITY OF THE REMAINING
ACTIVITY... HAVE REMOVED THUNDER AND SUB VFR CONDITIONS FOR MOST OF
THE TAF SITES. HOWEVER... WE STILL COULD SEE A STRAY SHOWER/STORM OR
TWO THIS EVENING AND OVERNIGHT (BEST CHANCE OVER THE NEXT TWO
HOURS)... ESPECIALLY NEAR KRWI... WHERE STORMS ARE CURRENTLY
DEVELOPING. GIVEN THE LACK OF RAIN SO FAR AT THE TAF SITES... HAVE
TAPERED BACK THE PRE-DAWN SUB-VFR CONDITIONS FOR THE MONDAY
MORNING. WILL STILL CARRY A TEMPO FOR MVFR VISBYS AT KGSO/KINT/KRWI
(ALL SITES THAT EXPERIENCED GOOD RAIN YESTERDAY AND PRE-DAWN SUB-VFR
CONDITIONS THIS MORNING) AND PATCHY STRATUS (REPRESENTED BY A
SCATTERED CLOUDS AT AROUND 300 FT IN THE TAFS). ANY SUB VFR
CONDITIONS THAT DEVELOP WILL QUICKLY BECOME VFR AFTER SUNRISE... BY
12Z TO 13Z AT THE LATEST. THE COVERAGE OF AFTERNOON SHOWERS AND
STORMS ARE EXPECTED TO BE A BIT LESS ON MONDAY... WITH MORE ISOLATED
TO WIDELY SCATTERED SHOWERS AND STORMS. THUS... WILL LEAVE OUT ANY
MENTION OF SHOWERS AND STORMS FROM THE TAFS AT THIS TIME FOR MONDAY
AFTERNOON/EVENING.
LOOKING AHEAD:
SCATTERED MAINLY AFTERNOON AND EVENING SHOWERS AND STORMS...AND
PATCHY MORNING FOG AND/OR LOW STRATUS WHERE STORMS OCCUR THE DAY
BEFORE...ARE EXPECTED THROUGH TUE NIGHT. THEN A MORE ACTIVE AND WET
PERIOD OF WEATHER MAY OCCUR DURING THE MID-LATE PORTION OF THE WEEK.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...NP
NEAR TERM...NP
SHORT TERM..NP
LONG TERM...RTE
AVIATION...BSD/NP
AREA FORECAST DISCUSSION
NWS BISMARCK ND
149 AM CDT SAT AUG 10 2013
.UPDATE...
ISSUED AT 149 AM CDT SAT AUG 10 2013
WILL EXPAND THE AERIAL COVERAGE OF CHANCES FOR SHOWERS OVER THE
SOUTHWEST THIS MORNING. MODELS KEYING IN ON PRECIPITATION
DEVELOPMENT 9-12Z ASSOCIATED WITH THE S/WV OVER SOUTHEAST MONTANA.
DO NOT ANTICIPATE THUNDER WITH ALL INSTABILITY SOUTHWEST OF THIS
AREA. OTHER EDITS THROUGH 12Z MAINLY FOR ADJUSTING HOURLY TRENDS.
UPDATE ISSUED AT 906 PM CDT FRI AUG 9 2013
MAIN UPDATE THIS EVENING WAS TO REMOVE MENTION OF PRECIPITATION
THROUGH AT LEAST 08Z SATURDAY IN THE FAR SOUTHWEST. ALSO
REDUCED/DELAYED POPS SATURDAY MORNING ACROSS FAR SOUTH CENTRAL
NORTH DAKOTA. THE LATEST HIGH RESOLUTION MODELS (HRRR/RAP) ALONG
WITH THE 00Z NAM...ARE ALL INITIALIZING/INDICATING PRECIPITATION
IN AREAS WHERE...IN REALITY...NOTHING IS OCCURRING. THE MODELS
ALREADY HAVE PRECIPITATION EITHER UP TO AND/OR IN OUR SOUTHWEST
ZONES AS OF 01Z. BUT THIS IS NOT THE CASE...HENCE THEIR SOLUTIONS
ARE PRETTY MUCH OBSOLETE FOR THE OVERNIGHT PERIOD AND INTO
SATURDAY MORNING. THE GFS/ECMWF ACTUALLY HAVE THE BEST HANDLE ON
THE CURRENT PRECIPITATION AREA...AND BOTH MODELS KEEP THE BEST
LIFT/OMEGA/PRECIPITATION SOUTH OF OUR BORDER TONIGHT. A SHORTWAVE
IS FORECAST TO MOVE ALONG THE MONTANA/WYOMING BORDER OVERNIGHT
WITH VERTICAL MOTION FIELD CONCENTRATED IN SOUTH DAKOTA. THUS
SCALED BACK POPS...AND REMOVED MENTION OF THUNDER IN FAR SOUTH
CENTRAL NORTH DAKOTA UNTIL SATURDAY AFTERNOON...AS ONLY THE FAR
SOUTHWEST WOULD BE VULNERABLE TO THUNDER LATE TONIGHT THROUGH
SATURDAY MORNING.
UPDATE ISSUED AT 541 PM CDT FRI AUG 9 2013
THE LATEST WATER VAPOR IMAGERY SHOWS NORTHERN/CENTRAL NORTH DAKOTA
DOMINATED BY NORTHWEST FLOW ALOFT...WHILE FAR SOUTHWEST/SOUTHERN
NORTH DAKOTA ARE BECOMING DETACHED FROM THE DOMINATE NORTHWEST FLOW.
HERE...WEAK RIDGING WAS OBSERVED ON WATER VAPOR WHICH EXTENDED FROM
THE FRONT RANGE OF THE ROCKIES INTO THE PANHANDLE OF IDAHO. THIS IS
INDUCING A WEST TO WEAK NORTHWEST FLOW. COUPLE OF SHORTWAVES TO NOTE
FOR TONIGHT/SATURDAY...THE FIRST WAS ALONG THE NORTHERN WYOMING AND
MONTANA BORDER...A SECOND IN CENTRAL IDAHO...AND A THIRD IN EAST
CENTRAL ALBERTA. THESE SHORTWAVES WILL TOP THE RIDGE AND SHIFT EAST
TONIGHT/SATURDAY. THE STRONGEST OMEGA/LIFT FOR TONIGHT AND SATURDAY
REMAINS IN SOUTH DAKOTA...BUT DOES GRAZE WESTERN AND SOUTHERN NORTH
DAKOTA LATER TONIGHT THROUGH SATURDAY. THE LATEST HRRR REFLECTIVITY
SUGGESTS THAT CONVECTION NOW OVER SOUTH CENTRAL MONTANA WILL SHIFT
EAST TONIGHT ALLOWING FOR THE POSSIBILITY OF ISOLATED SHOWERS IN
THE FAR SOUTHWEST AND EDGING FAIRLY CLOSE TO OUR FAR SOUTH CENTRAL
ZONES...MAINLY TOWARD AND AFTER 05Z SATURDAY. WILL CONTINUE TO
WATCH THIS ACTIVITY THIS EVENING. LATEST BOWMAN RADAR IS JUST
BEGINNING TO SHOW SOME WEAK REFLECTIVITY`S IN FAR SOUTHEAST
MONTANA. FOR THIS UPDATE...HAVE INCREASED SKY GRIDS FOR THE EARLY
PART OF THIS EVENING BASED ON VISIBLE SATELLITE AND SURFACE
OBSERVATIONS. REST OF THE FORECAST HAS THE TRENDS HANDLED WELL.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 339 PM CDT FRI AUG 9 2013
THE MAIN FORECAST ISSUE IN THE NEAR TERM IS PRECIPITATION CHANCES
TONIGHT AND SATURDAY. A WARM FRONT WILL LIFT NORTH INTO SOUTH
DAKOTA TONIGHT AS A SHORT WAVE TROUGH TOPS THE UPPER RIDGE. RAIN
COVERAGE IS EXPECTED TO REMAIN RATHER LIMITED ACROSS THE SOUTHERN
COUNTIES SO 20/30 POPS SEEM REASONABLE. SHOWERS AND ISOLATED
STORMS WILL LIKELY PUSH A BIT FARTHER NORTH INTO THE STATE ON
SATURDAY AFTERNOON. THERE SHOULD BE ENOUGH ELEVATED INSTABILITY TO
SUPPORT A FEW THUNDERSTORMS...BUT NO SEVERE WEATHER IS ANTICIPATED.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 339 PM CDT FRI AUG 9 2013
THE EXTENDED WILL BE CHARACTERIZED BY A MID/UPPER LEVEL RIDGE SLOWLY
BUILDING FROM THE ROCKIES EARLY IN THE PERIOD INTO THE CENTRAL
PLAINS BY THE END OF THE PERIOD. THIS WILL GENERATE A GRADUAL
WARMING TREND TO NEAR NORMAL TEMPERATURES BY FRIDAY.
LINGERING CONVECTION ALONG AND SOUTH OF I-94 SATURDAY EVENING SHOULD
WANE WITH THE LOSS OF DAYTIME HEATING.
AS A MID/UPPER RIDGE BUILDS INTO THE REGION...UPPER LEVEL DYNAMICS
WILL BE ON THE DECREASE. HOWEVER...LINGERING MOISTURE AND
INSTABILITY WILL GENERATE A SLIGHT CHANCE OF DIURNALLY DRIVEN
CONVECTION PRIMARILY ALONG AND WEST OF THE MISSOURI RIVER DURING THE
AFTERNOON/EVENING HOURS SUNDAY THROUGH WEDNESDAY.
THE UPPER RIDGE IS PROGGED TO BREAK DOWN SOMEWHAT THURSDAY AS A
RIDGE RUNNER CRESTS OVER THE ANTICYCLONIC RIDGE AXIS. FOR NOW
INDICATED SLIGHT CHANCE POPS AREAWIDE. HOWEVER...POPS MAY NEED TO BE
INCREASED IF FUTURE RUNS ADD CREDENCE TO THE 12Z SUITE OF MODEL
GUIDANCE.
THE RIDGE RUNNER SHORTWAVE IS THEN PROGGED TO PUSH EAST OF THE REGION
FRIDAY WITH PRECIP CHANCES ENDING FROM WEST TO EAST. HIGHS FRIDAY
LOOK TO RANGE FROM THE LOWER 80S EAST TO THE UPPER 80S WEST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 149 AM CDT SAT AUG 10 2013
VFR CONDITIONS THROUGH THE 06Z TAF PERIOD. WILL SEE A CHANCE FOR
SHOWERS OR AN ISOLATED THUNDERSTORM ALL TERMINALS AT SOME POINT IN
THE PERIOD.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...RP KINNEY
LONG TERM...TM
AVIATION...NH
AREA FORECAST DISCUSSION
NWS NORMAN OK
915 PM CDT SUN AUG 11 2013
.DISCUSSION...
A COUPLE OF CLUSTERS OF THUNDERSTORMS OVER SOUTHWEST OKLAHOMA AND
WESTERN NORTH TEXAS ARE LIKELY TO PERSIST THROUGH THE LATE
EVENING. SHORT-RANGE MODELS SUGGEST THAT CONVECTION WILL SHIFT
INTO NORTHWEST OKLAHOMA AFTER MIDNIGHT...AND PERHAPS FORM INTO AN
MCS ACROSS NORTHERN OKLAHOMA AND SOUTHERN KANSAS. THIS SCENARIO IS
STILL FAIRLY UNCERTAIN...SO THE EXISTING OVERNIGHT
POPS...QPF...ETC. STILL LOOK REASONABLE. THE FORECAST WAS UPDATED
EARLIER TO ACCOUNT FOR THE CONVECTIVE CLUSTERS...AND ADDITIONAL
UPDATES MAY BE NEEDED FOR SHORT-TERM TRENDS THIS
EVENING/OVERNIGHT.
OTHERWISE...NO CHANGES ARE CURRENTLY PLANNED FOR THE FORECAST.
&&
.PREV DISCUSSION... /ISSUED 641 PM CDT SUN AUG 11 2013/
AVIATION...
12/00Z TAFS...VFR CONDITIONS EXPECTED TO PREVAIL ACROSS THE REGION
OUTSIDE OF ANTICIPATED TSRA. FAIRLY WIDE VARIETY OF MODEL
SOLUTIONS ON EVOLUTION OF STORMS THIS EVENING THROUGH TOMORROW.
TAFS WILL BE BASED PRIMARILY ON HRRR AND WRF...WHICH YIELD
POTENTIAL FOR TSRA TO LINGER ACROSS SW OKLAHOMA THIS EVENING AND
COMPLEX OF STORMS TO APPROACH NORTHERN OKLAHOMA TOWARD 09Z FROM
KANSAS. THIS COMPLEX PROGD TO WEAKEN AND REDEVELOPMENT ACROSS
CENTRAL PORTIONS OF OKLAHOMA TOMORROW AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 73 92 72 90 / 20 30 40 40
HOBART OK 73 95 72 93 / 70 30 20 40
WICHITA FALLS TX 74 99 74 96 / 40 10 10 20
GAGE OK 69 93 68 87 / 50 40 40 50
PONCA CITY OK 71 90 69 86 / 40 40 60 50
DURANT OK 75 96 73 94 / 10 10 20 30
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
23/11
AREA FORECAST DISCUSSION
NWS NORMAN OK
641 PM CDT SUN AUG 11 2013
.AVIATION...
12/00Z TAFS...VFR CONDITIONS EXPECTED TO PREVAIL ACROSS THE REGION
OUTSIDE OF ANTICIPATED TSRA. FAIRLY WIDE VARIETY OF MODEL
SOLUTIONS ON EVOLUTION OF STORMS THIS EVENING THROUGH TOMORROW.
TAFS WILL BE BASED PRIMARILY ON HRRR AND WRF...WHICH YIELD
POTENTIAL FOR TSRA TO LINGER ACROSS SW OKLAHOMA THIS EVENING AND
COMPLEX OF STORMS TO APPROACH NORTHERN OKLAHOMA TOWARD 09Z FROM
KANSAS. THIS COMPLEX PROGD TO WEAKEN AND REDEVELOPMENT ACROSS
CENTRAL PORTIONS OF OKLAHOMA TOMORROW AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 73 92 72 90 / 20 30 40 40
HOBART OK 73 95 72 93 / 30 30 20 40
WICHITA FALLS TX 74 99 74 96 / 20 10 10 20
GAGE OK 69 93 68 87 / 50 40 40 50
PONCA CITY OK 71 90 69 86 / 40 40 60 50
DURANT OK 75 96 73 94 / 10 10 20 30
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
23/11/11
AREA FORECAST DISCUSSION
NWS MEDFORD OR
221 PM PDT SAT AUG 10 2013
.DISCUSSION...THE UPPER LOW CONTINUES TO SPIN OVER SOUTHWEST
OREGON WITH SEVERAL SHORTWAVES MOVING THROUGH TODAY. THUNDERSTORMS
ARE ALREADY BLOWING UP ALONG THE CASCADES AND EASTERN DOUGLAS
COUNTY. MEANWHILE THE MID LEVEL CLOUD SHIELD IN WESTERN SISKIYOU
COUNTY IS ERODING...SO IT COULD BE A TIMING ISSUE AS TO HOW MUCH
THUNDERSTORM ACTIVITY DEVELOPS IN NORTHERN CAL...JOSEPHINE AND
JACKSON COUNTIES. FURTHER NORTH THUNDERSTORMS WILL CONTINUE TO
INCREASE IN COVERAGE THROUGH EARLY THIS EVENING WITH SOME THAT COULD
BE MODERATE TO SEVERE PRODUCING MODERATE TO HEAVY RAIN...HAIL AND
GUSTY OUTFLOW WINDS. MODIFIED THE MORNING SOUNDING FOR THAT IT`S
EXPECTED TO LOOK LIKE THIS AFTERNOON AND IT`S SHOWING CAPE VALUES
NEAR 1400 J/KG AND PRECIPITABLE WATER VALUES NEAR AN INCH AND LIFTED
INDICES NEAR -6. THE RAP 13 AND LOCAL HRRR MODELS PUT MOST OF THE
QPF ALONG AND WEST OF THE CASCADES AND HAVE THUS INCREASED POPS AND
QPF IN THESE AREAS. HOWEVER MID LEVEL MOISTURE WILL INCREASE IN
NORTHERN KLAMATH AND LAKE COUNTIES WITH AT THE SAME TIME SHORTWAVES
ARE APPROACHING. SO EXPECT THIS AREA TO SEE INCREASED ACTIVITY AS
WELL.
RIGHT NOW...NOT MUCH IS GOING ON IN MODOC AND SOUTHERN LAKE
COUNTY...BUT WERE GETTING CUMULUS DEVELOPMENT AND EXPECT SOME
ACTIVITY THERE LATE THIS AFTERNOON.
THE UPPER LOW WILL MOVE INTO THE NORTHWEST PART OF THE FORECAST AREA
TONIGHT WITH A SOUTHWEST FLOW ALOFT DEVELOPING. THUNDERSTORMS SHOULD
DECREASE LATER THIS EVENING...THEN THE FOCUS FOR STORMS TONIGHT IS
EXPECTED TO SHIFT OVER THE NORTHERN CASCADES...NORTHERN LAKE AND
KLAMATH COUNTIES.
THE UPPER LOW FINALLY MOVES NORTH OF THE AREA SUNDAY AND WE`LL GET
INTO A SOUTHWEST FLOW ALOFT. THE CASCADES...EASTSIDE AND PARTS OF
THE SISKIYOUS HAVE THE BEST CHANCE OF GETTING THUNDERSTORMS IN THE
AFTERNOON AND EARLY EVENING...BUT IT`S POSSIBLE ISOLATED STORMS
COULD DEVELOP ALONG THE SISKIYOUS.
THE UPPER LOW CONTINUES TO MOVE NORTH AND WEAKEN MONDAY WITH A
CONTINUED SOUTHWEST FLOW OVER THE AREA. THE HIGHEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE CASCADES INTO NORTHERN LAKE AND
KLAMATH COUNTIES. EVEN THEN WERE NOT EXPECTING ANYTHING SIGNIFICANT.
THE EC AND GFS SHOW ANOTHER UPPER LOW SETTING SHOP WEST OF THE GULF
OF ALASKA WITH A CONTINUES SOUTHWEST FLOW OVER THE AREA. THIS WILL
RESULT IN DRY CONDITIONS WITH TEMPERATURES NEAR NORMAL. WHILE I
CANNOT RULE OUT ANY CHANCE OF PRECIPITATION EAST OF THE
CASCADES...THE ODDS ARE LOW THAT WE`LL GET ANYTHING. -PETRUCELLI
&&
.AVIATION...BASED ON THE 08/18Z TAF CYCLE.
MAIN CONCERN THROUGH THIS EVENING WILL BE SCATTERED THUNDERSTORMS
FOR INLAND LOCATIONS. SOME OF THESE STORMS COULD BECOME SEVERE
PRODUCING GUSTY OUTFLOW WINDS IN THE VICINITY OF STORMS AND HAIL.
THERE IS ALSO A CHANCE FOR BRIEF MVFR CIGS AND REDUCTION IN VIS IN
HEAVIER STORMS BETWEEN 22-03Z. STORMS MOVEMENT WILL GENERALLY MOVE
FROM EAST TO WEST AFFECTING THE WESTSIDE TERMINALS.
AT THE COAST...EXPECT IFR CIGS TO RETURN BETWEEN 2-3Z AND CONTINUE
INTO SATURDAY MORNING. THERE IS A CHANCE FOR SOME ELEVATED
CONVECTION TO BE IN THE VICINITY OF KOTH BETWEEN 22-2Z.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR
ORZ023>026-028-029.
RED FLAG WARNING UNTIL 11 PM PDT SUNDAY FOR ORZ027-030-031.
CA...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR CAZ080.
PACIFIC COASTAL WATERS...NONE.
$$
AREA FORECAST DISCUSSION
NWS PORTLAND OR
259 AM PDT SAT AUG 10 2013
.SYNOPSIS...AN UPPER LOW OVER THE NORTHERN CALIFORNIA COAST
WILL MOVE NORTH ALONG THE OREGON COAST THROUGH TONIGHT
...AND ALONG THE WASHINGTON COAST LATE SUNDAY INTO MONDAY. THIS WILL
CONTINUE THE THREAT OF SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND.
DRIER WEATHER WITH SEASONABLE TEMPERATURES WILL RETURN AS THE LOW
DEPARTS THE AREA ON MONDAY AND CONTINUE THROUGH MOST OF NEXT WEEK.
&&
SHORT TERM...TODAY THROUGH SUNDAY...NEARLY STATIONARY UPPER LEVEL LOW
PRESSURE ALONG THE COAST IS BEGINNING TO MAKE A NORTHWARD MOVEMENT
TODAY. WE CURRENTLY HAVE SOME SHOWERS DRIFTING EASTWARD THROUGH THE
NORTHERN HALF OF THE AREA EARLY THIS MORNING...WITH THUNDERSTORM
ACTIVITY CONFINED ALL AROUND US WHERE GREATER INSTABILITY WAS
LOCATED. THERE ARE STORMS NORTH AND EAST OF THE COUNTY WARNING AREA
IN WEST CENTRAL WASHINGTON WITH A REMOVED WEAKENED CLUSTER OF
THUNDERSTORMS IN NORTH CENTRAL/EASTERN OREGON WHERE A SHORTWAVE IS
MOVING THROUGH...AND SOUTH OF THE AREA CLOSER TO THE UPPER LOW. SPC
WRF AND HRRR SUGGEST THAT THE ACTIVITY ALONG THE NORTHERN TIER WILL
CONTINUE TO TRACK EASTWARD WITH THE SHOWER ACTIVITY MOVING OFFSHORE
AT DAYBREAK. THE ELEVATED SHOWERS/ISOLATED T-STORMS IN SOUTHERN
OREGON MAY MAKE A RUN AT OUR SOUTHERN ZONES THIS MORNING AS ANOTHER
WAVE WRAPS AROUND THE UPPER LOW...LIKELY GETTING IN AFTER DAYBREAK.
ADDITIONAL CONVECTION IN SOUTH CENTRAL OREGON WILL HEAD TOWARD THE N
OR/ S WA CASCADES LATER THIS MORNING THOUGH GUIDANCE IS MIXED AS TO
WHETHER THIS WILL SNEAK IN.
MEANWHILE...STRATUS HAS RETURNED INLAND UP THE COLUMBIA RIVER AND IS
NOW AT KELSO...AND BREAKS IN THE HIGHER CLOUDS IS ALLOWING THE FOG
PRODUCT TO MAKE OUT SOME LOW CLOUDS ALONG THE FOOTHILLS AS WELL. THE
REMAINDER OF THE AREA JUST HAS A MIX OF MID CLOUDS THUS FAR. IT IS
MOIST OUT THERE WITH DEWPOINTS IN THE MID 50S TO LOW 60S.
OUR ATTENTION WILL THEN FOCUS ON THE UPPER LOW AS IT WILL BE MOVING
NORTH ALONG THE COAST THROUGH THE AFTERNOON. THIS IS ABOUT AS GOOD OF
A SETUP AS IT GETS FOR THUNDER WEST OF THE CASCADES IN NORTHWEST
OREGON AND SOUTHWEST WASHINGTON. THE TRIGGER/INITIATION POINT FOR
MORE WIDESPREAD CONVECTION WILL BE ALOT CLOSER TODAY WITH THE UPPER
LOW FARTHER NORTH AND WEST THAN IT HAS BEEN IN DAYS PAST...AND AIDED
WITH THE MOMENTUM/NEGATIVE TILT OF THE LOW AND NOT JUST IMPULSES
ROTATING OUT AHEAD OF IT. HI-RES GUIDANCE SHOWS CONVECTIVE INITIATION
OVER THE CENTRAL OREGON CASCADES AND FOOTHILLS INTO CENTRAL AND
SOUTHERN OREGON IN THE EARLY AFTERNOON AS DIURNAL HEATING COMBINES
WITH GOOD FORCING FOR ASCENT ON THE NORTH AND EAST SIDE OF THE UPPER
LOW. SOUTH-SOUTHEAST STEERING FLOW REMAINS IN PLACE TO AID IN
DRIFTING STORMS OFF THE CASCADES WHERE THEY MAY NOT QUITE GET SURFACE
BASED. AREAS FARTHEST WEST WILL BE BATTLING THE STRONG ONSHORE
FLOW...THOUGH NO AREA IS IMMUNE TO A CHANCE.
INSTABILITY PARAMETERS ARE RIGHT ON PAR FOR THE CASCADES AND MUCH
BETTER FOR THE VALLEY THAN FRIDAY`S VALUES. MID LEVEL LAPSE RATES
OVER THE VALLEY ARE BETTER...AND CAPPING IS SIGNIFICANTLY LESS.
HAZARDS INCLUDE THE POTENTIAL FOR HAIL...GUSTY WINDS...AND HEAVY
RAIN...IN ADDITION TO ANOTHER ROUND OF ABUNDANT LIGHTNING. CAPE IN
THE -10 TO -30 C LEVEL IS FAVORABLE FOR HAIL PRODUCTION GIVEN THE
STEEP MID LEVEL LAPSE RATES THAT TYPICALLY OCCUR IN PROXIMITY TO THE
UPPER LOW. FREEZING LEVELS WILL BE AROUND 11-12K FT...SO ANY 50DBZ
ECHOES ABOVE ROUGHLY 30K FT AGL HAVE THE POTENTIAL FOR SEVERE HAIL.
FORECAST SOUNDINGS DEPICT SOMEWHAT DRY SUBCLOUD LAYERS WHICH
CONTRIBUTES TO MODEST DOWNDRAFT CAPE VALUES INCREASING THE WIND
THREAT. AND CORFIDI VECTORS SUGGEST LOW TO MODERATE STORM
MOTION....AND THIS COUPLED WITH A SLOW MOVING UPPER LOW AND
PRECIPITABLE WATER VALUES ABOVE 1 INCH TO EVEN AS HIGH AS 1.25 INCHES
WILL BRING THE POTENTIAL FOR VERY MODERATE TO HEAVY RAIN UNDER ANY
THUNDERSTORMS.. SPC`S DAY 1 OUTLOOK SUMS THINGS UP WELL...AND EXPECT
DISCRETE STORMS TO DEVELOP INTO A FEW MULTICELL CLUSTERS CAPABLE OF
MARGINALLY SEVERE HAIL AND ISOLATED DAMAGING WINDS.
THE LOW WILL EVENTUALLY REACH THE SOUTH WASHINGTON COAST LATE SUNDAY
AND SUNDAY NIGHT. THIS SHOULD CONTINUE TO SPREAD SOME SHOWERS AND
THUNDERSTORMS ON SUNDAY MAINLY INTO THE CASCADES WHERE THE MODELS
SHOW LINGERING INSTABILITY AND MODEST SHEAR...THOUGH MOISTURE
PARAMETERS ARE WEAKER AS IS FORCING. AFTER THE LEFTOVER CLOUDS AND
SHOWERS FROM THE CONVECTION OF SATURDAY NIGHT MOVE OUT SUNDAY
MORNING...EXPECT ONSHORE FLOW WEST OF THE CASCADES TO BE FAIRLY
STRONG BRINGING MORE AND DEEPER LOW CLOUDS...AND KEEPING THE NOW
SMALLER THUNDER CHANCES TO THE HIGH TERRAIN.
WITH THE LOW OFF THE WASHINGTON COAST ON MONDAY...EXPECT A BIT MORE
SUNSHINE ON MONDAY AFTERNOON AFTER THE MORNING CLOUDS BURN OFF. THE
BEST CHANCE OF ANY THUNDER ON MONDAY WILL BE IN THE HIGHER CASCADES.
NOT MUCH WAS CHANGED ON THE FORECAST BEYOND THE SHORT TERM...GIVEN
THE FOCUS ON THE HIGH IMPACT SHORT TERM FORECAST. KMD
.LONG TERM...MONDAY NIGHT THROUGH THURSDAY...THE MODELS SHOW THE LOW
FROM THE WEEKEND WELL NORTH AND OFF THE COAST THROUGH THE PERIOD...
WITH ANOTHER LOW SETTING UP WELL OFFSHORE OUT NEAR 140W OR SO. THIS
PUTS SOUTHWEST WASHINGTON AND NORTHWEST OREGON IN LIGHT SOUTHWEST
FLOW THAT SHOULD MAINTAIN LIGHT ONSHORE FLOW AND SEASONABLE TO
SLIGHTLY ABOVE NORMAL TEMPS. THE MAIN THUNDERSTORM THREAT MAY STAY
JUST TO OUR EAST. THE ECMWF AND GEM START TO ALLOW THE OFFSHORE LOW
TO APPROACH OUR AREA BY NEXT THURSDAY...BUT FOR NOW WILL HOLD OFF ON
ANY PRECIPITATION OR TOO MUCH COOLING UNTIL THIS TREND BECOMES MORE
ESTABLISHED. TOLLESON
&&
.AVIATION...IFR CONDITIONS WILL CONTINUE ALONG THE COAST TODAY AND
TONIGHT...WITH PERHAPS SOME BRIEF IMPROVEMENT TO MVFR ALONG THE
NORTH COAST DURING THE AFTERNOON. ONSHORE FLOW SHOULD BRING MVFR
STRATUS TO MOST OF THE WILLAMETTE VALLEY AND THE SOUTHWEST
WASHINGTON LOWLANDS THIS MORNING. VFR CONDITIONS WILL LIKELY
RETURN BY 18-20Z. THERE WILL LIKELY BE A THREAT OF SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING...PARTICULARLY ACROSS
NORTHERN PARTS OF THE DISTRICT.
KPDX AND APPROACHES...MVFR CONDITIONS WILL LIKELY DEVELOP AROUND
12Z THIS MORNING AND CONTINUE THROUGH 18-19Z. EXPECT VFR
CONDITIONS THEREAFTER. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
LATER TODAY...PARTICULARLY AFTER 20Z.
&&
.MARINE...LITTLE CHANGE EXPECTED THROUGH EARLY NEXT WEEK WITH N
TO NW WINDS GENERALLY REMAINING IN THE 10 TO 20 KT RANGE.
OTHERWISE...A 4 TO 6 FT WESTERLY SWELL WILL SLOWLY SUBSIDE TODAY
AND SUNDAY...DROPPING SEAS BACK DOWN INTO THE 3 FT RANGE FOR
EARLY NEXT WEEK.
&&
.FIRE WEATHER...RED FLAG WARNING FOR ZONES 606 AND 608 HAS EXPIRED AS
THERE WERE WETTING RAINS IN PORTIONS OF THIS AREA. THE RED FLAG
REMAINS IN ZONES 660...605 AND 607 THROUGH SATURDAY AT THIS
POINT...DUE TO VERY ABUNDANT LIGHTNING EXPECTED AS WAS SEEN ON
FRIDAY...THOUGH THERE WERE SOME WETTING RAINS HERE TOO.
THUNDERSTORMS WILL INCREASINGLY SPREAD NORTH AND BECOME INCREASINGLY
WET AGAIN THIS AFTERNOON AND EVENING.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT SATURDAY FOR ZONE 605-ZONE 607.
WA...RED FLAG WARNING UNTIL 11 PM PDT SATURDAY FOR ZONE 660.
PZ...NONE.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1137 PM EDT SUN AUG 11 2013
.SYNOPSIS...
THE REGION WILL REMAIN IN A MID-TROPOSPHERIC TROUGH FOR MOST OF
THE NEXT 7-10 DAYS. A STRONG WAVE IN THE UPPER LEVEL PATTERN
SHOULD PUSH A STRONG FRONTAL SYSTEM INTO PENNSYLVANIA TUESDAY
WHICH SHOULD TRIGGER SOME SHOWERS. BEHIND THIS SYSTEM ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
THE TONGUE OF HIGH THETA-E AIR OVER SOUTHERN PA PROVED QUITE PESKY
WITH EVOLUTION OF SHOWERS THIS EVENING. THE EASTERN BATCH HAS WEAKENED
ABOUT EXITED STAGE RIGHT SO LOWERED POPS IN LANCASTER COUNTY. THE
SHOWERS OVER THE WEST ARE NOW IN THE HIGHEST THETA-E AIR MOVING
ACROSS BEDFORD-FULTON AND FRANKLIN COUNTIES. TRIED TO SHOW THEM
SLIDING SOUTH-SOUTHEAST NEXT FEW HOURS.
ANOTHER BATCH IS ABOUT TO MOVE INTO SOMERSET COUNTY. PUT THESE IN
GRIDS TOO. THE HRRR AND RAP FINALLY THINK THEY SHOULD BE THERE
MOST OF THIS ACTIVITY IS KAPUT IN THE 6-8Z RANGE BASED ON MODELS.
BUT PUT AREA OF LIKELY IN UNTIL 5Z AND THEN TAPERED OFF. ALL OF
THIS SHOULD BE FOCUSED IN SOUTHERN TIER COUNTIES. THE THETA-E
GRADIENT IS NOT GOING NORTH TONIGHT.
ELSEWHERE....NORTHERN HALF PA LOOKS ABOUT CLEAR ON 11-3.9 CHANNEL
THIN CIRRUS UP TO JUST SOUTH OF STATE COLLEGE...THOUGH A VIEW FROM
THE SURFACE ONE WOULD SEE CLOUDS OVER SOUTHERN SKY OVER MOST OF
CENTRAL PA. ROUND EARTH ISSUE...
THOSE CLEAR SKIES SHOULD PERHAPS GET SOME UPPER 40S IN NW PA.
GOING TO BE A GOOD COMFORTABLE NIGHT NORTHWEST AREAS ABOUT
50...FEW COLDER SPOTS AND CLOUDIER SOUTHERN AREAS IN THE MID-60S.
SHOULD BE A GOOD START TO THE DAY...MORE CLOUDS IN SOUTH THAN
NORTH.
&&
.SHORT TERM /8 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
WILL TAKE SOME TIME TO BURN OFF LOW CLOUDS MONDAY MORNING. SHOULD
BE A RELATIVELY PLEASANT LATE MID-AUGUST DAY. CANNOT RULE STRAY
SHOWERS AND/OR ISOLATED THUNDERSTORMS. BUT POPS SHOULD BE BELOW 30
PERCENT MOST AREAS. INCREASED POPS IN SECOND HALF OF
AFTERNOON...INSTABILITY AND HINTS OF QPF IN MODELS...ALL OF
THEM...IN SOUTHEAST. ADDITIONAL ISSUES WITH MOISTURE SURGE AHEAD
OF FRONT IN NORTHWEST. FORECAST REFLECTS INCREASED POPS IN
SOUTHEAST AND NORTHWEST MONDAY AFTERNOON.
OTHER CHANGES TO MONDAY WERE TEMPERATURE TWEAKS.
THE STRONG FRONTAL SYSTEM WILL BECOME AN ISSUE OVERNIGHT MONDAY
INTO TUESDAY. FRONTAL TIMING SUGGESTS CHANCE RAIN AND THUNDER
COMES UP AFTER MIDNIGHT IN WESTERN AREAS AND STROLLS EASTWARD WITH
TIME DURING OVERNIGHT INTO TUESDAY MORNING. IF THE FRONT SPEEDS UP
TUESDAY AFTERNOON COULD TURN OUT OKAY. TRIED TO SHOW POPS LOWERING
IN THE SECOND HALF OF AFTERNOON WEST TO EAST.
ALWAYS A POP PROBLEMS AS SREF HAS THE PATTERN OF DECREASED POPS
BUT IT IS SO WET BIASED ONE CANNOT USE IT EFFECTIVELY IN GRIDS.
THE GEFS SHOWS LOWER POPS AFTER 18Z TUESDAY AS DO ALL THE
MODELS...NAM/GFS. SUSPECT PW TELLS US TWO IMPORTANT THINGS 1) NOT
GOING TO BE A BIG RAIN EVENT AND 2) PW DROPS IN AFTERNOON IMPLYING
THE AFTERNOON COULD BE RAIN FREE IN WEST. POPS REFLECT THIS
THINKING AS BEST AS PRACTICABLE.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
GENERALLY COSMETIC CHANGES MADE TO PREVIOUS EXTENDED FORECAST
TODAY AS PATTERN WILL BE DOMINATED BY THE ROCKY MOUNTAIN UPPER
RIDGE AND DOWNSTREAM LONG WAVE TROF FROM EASTERN CANADA TO THE MID
ATLANTIC REGION THIS WEEK.
BEST CHANCE OF PRECIPITATION WILL COME FROM A FRONTAL SYSTEM
MONDAY NIGHT AND TUESDAY BEFORE THE MEAN UPPER TROF AXIS SETTLES
EAST OF THE AREA FOR THE LATTER HALF OF THIS WEEK. AS PREVIOUSLY
MENTIONED...THE BIGGEST IMPACT WILL BE A FRESH SHOT OF DRIER AND
COOLER AIR FOR THE MIDDLE OF THE WEEK AS TEMPERATURES DROP BELOW
AVERAGE ON WED AND THU. FLOW BEGINS TO TURN SW LATE IN THE PERIOD
FOR SOME MODERATION AS THE WEEKEND APPROACHES.
LATE IN THE PERIOD...WESTERN ATLANTIC UPPER RIDGE RETROGRADES AND
AMPLIFIES OVER BERMUDA. THIS WILL HELP TO SHARPEN THE EAST COAST
TROF AXIS AND DIRECT DEEPER LAYER MOISTURE NORTHWARD INTO THE MID
ATLANTIC REGION NEXT WEEKEND. HAVE INTRODUCED SHOWER CHANCES AS A
RESULT...MAINLY ON SUNDAY. GULF COAST TROPICAL DEVELOPMENT IS
POSSIBLE WITH THIS SURGE OF MOISTURE...SO WE`LL BE WATCHING THIS
WITH INTEREST AS THE WEEK PROGRESSES.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
PRIMARILY VFR CONDITIONS PREVAIL ACROSS CENTRAL PA THIS
EVENING...WITH ISOLATED SHOWERS AND A RARE TSTM DRIFTING W-E
ALONG THE PA TURNPIKE BRINGING SHORT-LIVED REDUCTIONS. THESE
SHOULD DIMINISH DURING THE EARLY MORNING HOURS.
PATCHY MAINLY MVFR FOG /ISO IFR/ WILL DEVELOP BETWEEN 06Z-09Z AND
DISSOLVE THROUGH MID MORNING. CHC OF LOWER STRATOCU ACROSS SE
LATE.
FOR MONDAY...PRIMARILY VFR CONDITIONS CONTINUE. CANNOT RULE OUT
STRAY SHOWERS AND/OR ISOLATED THUNDERSTORMS...BUT MAJORITY OF THE
DAY WILL BE DRY IN ANY ONE LOCATION. MODELS HINTING AT HIGHER POPS
IN THE SE DURING SECOND HALF OF AFTERNOON BASED ON INCREASING
INSTABILITY AND HINTS OF QPF IN JUST ABOUT ALL MODELS.
A STRONG FRONTAL SYSTEM SLIDES IN FROM THE NW OVERNIGHT MONDAY
INTO TUESDAY...WITH CONDITIONS DETERIORATING. AREA OF RAIN AND SCT
THUNDER WORKS IN FROM THE NW MON NIGHT...EXITING SE BY TUE AFT.
OUTLOOK...
MON...PRIMARILY VFR. ISO SHRA/TSTM...HIGHEST CHANCE IN SE LATE AFT.
MON NIGHT...DETERIORATING CONDITIONS FROM NW. SHOWERS/TSTMS LKLY
MAINLY OVER THE NW AIRFIELDS. MAINLY VFR SE.
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS...ESP BEFORE NOON.
WED-FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...ROSS/DEVOIR
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1048 PM EDT SUN AUG 11 2013
.SYNOPSIS...
THE REGION WILL REMAIN IN A MID-TROPOSPHERIC TROUGH FOR MOST OF
THE NEXT 7-10 DAYS. A STRONG WAVE IN THE UPPER LEVEL PATTERN
SHOULD PUSH A STRONG FRONTAL SYSTEM INTO PENNSYLVANIA TUESDAY
WHICH SHOULD TRIGGER SOME SHOWERS. BEHIND THIS SYSTEM ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 8 AM MONDAY MORNING/...
THE TONGUE OF HIGH THETA-E AIR OVER SOUTHERN PA PROVED QUITE PESKY
WITH EVOLUTION OF SHOWERS THIS EVENING. THE EASTERN BATCH HAS WEAKENED
ABOUT EXITED STAGE RIGHT SO LOWERED POPS IN LANCASTER COUNTY. THE
SHOWERS OVER THE WEST ARE NOW IN THE HIGHEST THETA-E AIR MOVING
ACROSS BEDFORD-FULTON AND FRANKLIN COUNTIES. TRIED TO SHOW THEM
SLIDING SOUTH-SOUTHEAST NEXT FEW HOURS.
ANOTHER BATCH IS ABOUT TO MOVE INTO SOMERSET COUNTY. PUT THESE IN
GRIDS TOO. THE HRRR AND RAP FINALLY THINK THEY SHOULD BE THERE
MOST OF THIS ACTIVITY IS KAPUT IN THE 6-8Z RANGE BASED ON MODELS.
BUT PUT AREA OF LIKELY IN UNTIL 5Z AND THEN TAPERED OFF. ALL OF
THIS SHOULD BE FOCUSED IN SOUTHERN TIER COUNTIES. THE THETA-E
GRADIENT IS NOT GOING NORTH TONIGHT.
ELSEWHERE....NORTHERN HALF PA LOOKS ABOUT CLEAR ON 11-3.9 CHANNEL
THIN CIRRUS UP TO JUST SOUTH OF STATE COLLEGE...THOUGH A VIEW FROM
THE SURFACE ONE WOULD SEE CLOUDS OVER SOUTHERN SKY OVER MOST OF
CENTRAL PA. ROUND EARTH ISSUE...
THOSE CLEAR SKIES SHOULD PERHAPS GET SOME UPPER 40S IN NW PA.
GOING TO BE A GOOD COMFORTABLE NIGHT NORTHWEST AREAS ABOUT
50...FEW COLDER SPOTS AND CLOUDIER SOUTHERN AREAS IN THE MID-60S.
SHOULD BE A GOOD START TO THE DAY...MORE CLOUDS IN SOUTH THAN
NORTH.
&&
.SHORT TERM /8 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
WILL TAKE SOME TIME TO BURN OFF LOW CLOUDS MONDAY MORNING. SHOULD
BE A RELATIVELY PLEASANT LATE MID-AUGUST DAY. CANNOT RULE STRAY
SHOWERS AND/OR ISOLATED THUNDERSTORMS. BUT POPS SHOULD BE BELOW 30
PERCENT MOST AREAS. INCREASED POPS IN SECOND HALF OF
AFTERNOON...INSTABILITY AND HINTS OF QPF IN MODELS...ALL OF
THEM...IN SOUTHEAST. ADDITIONAL ISSUES WITH MOISTURE SURGE AHEAD
OF FRONT IN NORTHWEST. FORECAST REFLECTS INCREASED POPS IN
SOUTHEAST AND NORTHWEST MONDAY AFTERNOON.
OTHER CHANGES TO MONDAY WERE TEMPERATURE TWEAKS.
THE STRONG FRONTAL SYSTEM WILL BECOME AN ISSUE OVERNIGHT MONDAY
INTO TUESDAY. FRONTAL TIMING SUGGESTS CHANCE RAIN AND THUNDER
COMES UP AFTER MIDNIGHT IN WESTERN AREAS AND STROLLS EASTWARD WITH
TIME DURING OVERNIGHT INTO TUESDAY MORNING. IF THE FRONT SPEEDS UP
TUESDAY AFTERNOON COULD TURN OUT OKAY. TRIED TO SHOW POPS LOWERING
IN THE SECOND HALF OF AFTERNOON WEST TO EAST.
ALWAYS A POP PROBLEMS AS SREF HAS THE PATTERN OF DECREASED POPS
BUT IT IS SO WET BIASED ONE CANNOT USE IT EFFECTIVELY IN GRIDS.
THE GEFS SHOWS LOWER POPS AFTER 18Z TUESDAY AS DO ALL THE
MODELS...NAM/GFS. SUSPECT PW TELLS US TWO IMPORTANT THINGS 1) NOT
GOING TO BE A BIG RAIN EVENT AND 2) PW DROPS IN AFTERNOON IMPLYING
THE AFTERNOON COULD BE RAIN FREE IN WEST. POPS REFLECT THIS
THINKING AS BEST AS PRACTICABLE.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
GENERALLY COSMETIC CHANGES MADE TO PREVIOUS EXTENDED FORECAST
TODAY AS PATTERN WILL BE DOMINATED BY THE ROCKY MOUNTAIN UPPER
RIDGE AND DOWNSTREAM LONG WAVE TROF FROM EASTERN CANADA TO THE MID
ATLANTIC REGION THIS WEEK.
BEST CHANCE OF PRECIPITATION WILL COME FROM A FRONTAL SYSTEM
MONDAY NIGHT AND TUESDAY BEFORE THE MEAN UPPER TROF AXIS SETTLES
EAST OF THE AREA FOR THE LATTER HALF OF THIS WEEK. AS PREVIOUSLY
MENTIONED...THE BIGGEST IMPACT WILL BE A FRESH SHOT OF DRIER AND
COOLER AIR FOR THE MIDDLE OF THE WEEK AS TEMPERATURES DROP BELOW
AVERAGE ON WED AND THU. FLOW BEGINS TO TURN SW LATE IN THE PERIOD
FOR SOME MODERATION AS THE WEEKEND APPROACHES.
LATE IN THE PERIOD...WESTERN ATLANTIC UPPER RIDGE RETROGRADES AND
AMPLIFIES OVER BERMUDA. THIS WILL HELP TO SHARPEN THE EAST COAST
TROF AXIS AND DIRECT DEEPER LAYER MOISTURE NORTHWARD INTO THE MID
ATLANTIC REGION NEXT WEEKEND. HAVE INTRODUCED SHOWER CHANCES AS A
RESULT...MAINLY ON SUNDAY. GULF COAST TROPICAL DEVELOPMENT IS
POSSIBLE WITH THIS SURGE OF MOISTURE...SO WE`LL BE WATCHING THIS
WITH INTEREST AS THE WEEK PROGRESSES.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
VFR CONDS WILL PREVAIL THRU THE AFTN. COSPA DATA SUGGESTS AN
ISOLD SHOWER/TSTM IS PSBL OVER THE SCNTRL TERMINALS...BUT
PROBABILITY/COVERAGE IS TOO LOW TO INCLUDE IN TAFS ATTM. SOME LOW
CLOUDS AND FOG ARE PSBL TNT INTO MONDAY MORNING...AND HAVE ADDED
BR/VCFG AND RESTRICTED VIS WITH THE 18Z ISSUANCE. CONFIDENCE IN
IFR IS MEDIUM GIVEN FAIRLY GOOD AGREEMENT AMONGST THE GUIDANCE.
WILL MAINTAIN REGULAR TAF AT BFD USING TOTAL OB CONCEPT...AND THE
FACT THAT THERE IS NO SIG WX. IF THE OUTAGE CONTINUES INTO TONIGHT
LATER ISSUANCES MAY INCLUDE AMD NOT SKED GIVEN THE PROSPECT OF FOG
AND LOW CIGS OVERNIGHT.
OUTLOOK...
MON...VFR. SHOWERS/TSTMS LKLY OVER THE NW AIRFIELDS MON NGT.
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS.
WED-THU...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...ROSS/DEVOIR
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1046 PM CDT SUN AUG 11 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 317 PM CDT SUN AUG 11 2013
SURFACE BOUNDARY HAS SET UP FROM NEAR YANKTON SOUTH DAKOTA
NORTHEASTWARD TO CANTON AND EAST TO SPENCER. AIRMASS REMAINS WARM
AND UNSTABLE SOUTH OF THIS BOUNDARY WHERE TEMPERATURES HAVE ALREADY
RISEN INTO THE LOWER 80S WITH DEWPOINTS NEAR 70. RAP SOUNDINGS
SUGGEST THAT MUCAPE VALUES ARE OVER 2000 J/KG WITH EFFECTIVE SHEAR
NEAR 25 TO 35 KT IN THIS AREA. WITH CONTINUED DESTABILIZATION AND
VERY LITTLE CAPPING INDICATED...SCATTERED STORMS ARE EXPECTED TO
DEVELOP ACROSS THE SOUTHEASTERN CORNER OF THE FORECAST AREA WITHIN
THE NEXT FEW HOURS. STRATUS FIELD ENCOMPASSING THE BULK OF THE
FORECAST AREA COULD KEEP THE FOCUS JUST SOUTH OF THE FORECAST AREA
WHERE MID LEVEL LAPSE RATES ARE A BIT MORE IMPRESSIVE AND A LARGE
CUMULUS FIELD CAN BE SEEN ON SATELLITE.
WITH THE SURFACE LOW SLOWLY EDGING EASTWARD THROUGH THE
EVENING...THE BOUNDARY SHOULD BEGIN TO ADVANCE EASTWARD AND IS
EXPECTED TO EXIT THE FORECAST AREA BY AROUND 03Z. IF STORMS MANAGE
TO DEVELOP WITHIN OUR CWA...A FEW SEVERE STORMS WILL BE POSSIBLE AND
WILL POSE A THREAT OF HAIL UP TO GOLF BALLS AND 60 MPH WIND GUSTS.
PRECIPITABLE WATER VALUES REMAIN QUITE HIGH AT 1.5" OR HIGHER...SO
HEAVY RAINFALL WILL ALSO BE LIKELY WITH WITH SHOWERS AND STORMS.
STRATUS NEAR THE BOUNDARY WILL ALSO GRADUALLY BEGIN TO CLEAR OUR
FROM NORTHWEST TO SOUTHEAST THROUGH THIS EVENING BEHIND THIS
SYSTEM...BUT COULD BECOME HUNG UP NEAR THE MISSOURI VALLEY AND SOUTH
CENTRAL IOWA NEAR THE BAGGY PORTION OF THE FRONT. MONDAY WILL BE
ANOTHER PLEASANT LATE SUMMER DAY WITH RELATIVELY LIGHT WINDS AND
SLIGHTLY BELOW NORMAL TEMPERATURES AND PARTLY CLOUDY SKIES. HIGHS
WILL BE IN THE MID 70S TO LOWER 80S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 317 PM CDT SUN AUG 11 2013
MONDAY NIGHT THROUGH WEDNESDAY LOOKS TO STAY MAINLY DRY OVER THE
AREA AS WE REMAIN IN BETWEEN A DIGGING TROUGH TOWARDS THE EAST COAST
AND A BUILDING RIDGE WEST OF THE ROCKIES. HIGH PRESSURE DROPPING OUT
OF CANADA TO OUR EAST...WILL KEEP COOL EASTERLY FLOW OVER US...AND
SHOULD ALSO KEEP MOST OF THE INSTABILITY SOUTH AND WEST OF OUR CWA.
WOULD EXPECT DAILY ISOLATED TO SCATTERED STORM DEVELOPMENT IN THE
WESTERN PLAINS WHERE THE SOUTHEASTERLY UPSLOPE FLOW...CONVERGENCE
AND INSTABILITY ARE MAXIMIZED. HOWEVER THINK MOST OF THAT ACTIVITY
WILL STAY OUT OF OUR AREA. THE EXCEPTION COULD BE IN THE FAR
SOUTHWEST CORNER OF OUR CWA...TOWARDS GREGORY COUNTY...WHICH IS
CLOSE ENOUGH TO THIS ACTION TO WARRANT A LOW CHANCE POP EACH DAY AND
NIGHT. NAM IS A BIT MORE AGGRESSIVE WITH CONVECTION ALONG THE
MISSOURI RIVER AND WEST OF THE JAMES RIVER MONDAY NIGHT INTO
TUESDAY. IT IS FURTHER EAST WITH THE 850 MB BOUNDARY...ALLOWING
CONVERGENCE AND INSTABILITY TO CREEP FURTHER NORTHEAST. BUT SINCE IT
IS A PRETTY BIG OUTLIER AT THIS TIME...WILL STICK CLOSER TO THE
ECMWF AND GFS SOLUTIONS. LOWS MONDAY NIGHT AND TUESDAY NIGHT
DEPENDENT ON CLOUD COVER...BUT AT THIS POINT THINKING WE SEE ENOUGH
CLEARING TO GET SOME COOL LOWS EAST OF THE JAMES RIVER...WITH LOW
AND MID 50S EXPECTED. HIGHS TUESDAY AND WEDNESDAY WILL STAY BELOW
NORMAL...WITH MID AND UPPER 70S COMMON.
BY WEDNESDAY NIGHT THE RIDGING BEGINS TO PUSH NORTHEAST CLOSER TO
THE AREA AS OUR HIGH PRESSURE MOVES OFF TO THE EAST. THIS WILL ALLOW
LOW LEVEL SOUTHEASTERLY WINDS TO MOVE FURTHER INTO THE
AREA...ALLOWING FOR A SLOW INCREASE IN INSTABILITY. THIS WILL ALSO
ALLOW FOR NIGHTLY INCREASES IN THE LOW LEVEL JET WHICH SHOULD ACT TO
HELP INCREASE OUR PRECIP CHANCES. WEDNESDAY NIGHT MAY SEE SOME
ACTIVITY MAKE IT CLOSE TO INTERSTATE 29...AND BY THURSDAY INTO
THURSDAY NIGHT WE MIGHT BE ABLE TO GET SOME CONVECTION ACROSS THE
CWA. INSTABILITY STILL ON THE LOW SIDE AND FORCING NOT THAT
IMPRESSIVE...SO ONLY LOW CHANCE POPS WARRANTED AT THIS TIME. AS THE
RIDGING CONTINUES TO SLOWLY BUILD IN...STARTING TO LOOK LIKE FRIDAY
INTO THE WEEKEND WILL STAY DRY...WITH A WARMING TREND EACH DAY.
THURSDAY WILL SEE MID 70S TO NEAR 80...WITH READINGS NEAR 80 TO 85
OVER THE WEEKEND.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1046 PM CDT SUN AUG 11 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD AS
HIGH PRESSURE BUILDS INTO THE REGION BEHIND A DEPARTING FRONT. THE
EXCEPTION WILL BE SOME PATCHY MVFR VSBYS WITH RADIATIONAL FOG LATE
TONIGHT/EARLY MONDAY MORNING DUE TO LIGHT WINDS...CLEARING
SKIES...AND RESIDUAL MOISTURE FROM RECENT RAINFALL. CONFIDENCE ON
FOG IS LOW HOWEVER AS IT DEPENDS ON THE COVERAGE OF HIGH CLOUDS
FROM THUNDERSTORMS TO THE WEST AND SOUTH.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
611 PM CDT SUN AUG 11 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 317 PM CDT SUN AUG 11 2013
SURFACE BOUNDARY HAS SET UP FROM NEAR YANKTON SOUTH DAKOTA
NORTHEASTWARD TO CANTON AND EAST TO SPENCER. AIRMASS REMAINS WARM
AND UNSTABLE SOUTH OF THIS BOUNDARY WHERE TEMPERATURES HAVE ALREADY
RISEN INTO THE LOWER 80S WITH DEWPOINTS NEAR 70. RAP SOUNDINGS
SUGGEST THAT MUCAPE VALUES ARE OVER 2000 J/KG WITH EFFECTIVE SHEAR
NEAR 25 TO 35 KT IN THIS AREA. WITH CONTINUED DESTABILIZATION AND
VERY LITTLE CAPPING INDICATED...SCATTERED STORMS ARE EXPECTED TO
DEVELOP ACROSS THE SOUTHEASTERN CORNER OF THE FORECAST AREA WITHIN
THE NEXT FEW HOURS. STRATUS FIELD ENCOMPASSING THE BULK OF THE
FORECAST AREA COULD KEEP THE FOCUS JUST SOUTH OF THE FORECAST AREA
WHERE MID LEVEL LAPSE RATES ARE A BIT MORE IMPRESSIVE AND A LARGE
CUMULUS FIELD CAN BE SEEN ON SATELLITE.
WITH THE SURFACE LOW SLOWLY EDGING EASTWARD THROUGH THE
EVENING...THE BOUNDARY SHOULD BEGIN TO ADVANCE EASTWARD AND IS
EXPECTED TO EXIT THE FORECAST AREA BY AROUND 03Z. IF STORMS MANAGE
TO DEVELOP WITHIN OUR CWA...A FEW SEVERE STORMS WILL BE POSSIBLE AND
WILL POSE A THREAT OF HAIL UP TO GOLF BALLS AND 60 MPH WIND GUSTS.
PRECIPITABLE WATER VALUES REMAIN QUITE HIGH AT 1.5" OR HIGHER...SO
HEAVY RAINFALL WILL ALSO BE LIKELY WITH WITH SHOWERS AND STORMS.
STRATUS NEAR THE BOUNDARY WILL ALSO GRADUALLY BEGIN TO CLEAR OUR
FROM NORTHWEST TO SOUTHEAST THROUGH THIS EVENING BEHIND THIS
SYSTEM...BUT COULD BECOME HUNG UP NEAR THE MISSOURI VALLEY AND SOUTH
CENTRAL IOWA NEAR THE BAGGY PORTION OF THE FRONT. MONDAY WILL BE
ANOTHER PLEASANT LATE SUMMER DAY WITH RELATIVELY LIGHT WINDS AND
SLIGHTLY BELOW NORMAL TEMPERATURES AND PARTLY CLOUDY SKIES. HIGHS
WILL BE IN THE MID 70S TO LOWER 80S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 317 PM CDT SUN AUG 11 2013
MONDAY NIGHT THROUGH WEDNESDAY LOOKS TO STAY MAINLY DRY OVER THE
AREA AS WE REMAIN IN BETWEEN A DIGGING TROUGH TOWARDS THE EAST COAST
AND A BUILDING RIDGE WEST OF THE ROCKIES. HIGH PRESSURE DROPPING OUT
OF CANADA TO OUR EAST...WILL KEEP COOL EASTERLY FLOW OVER US...AND
SHOULD ALSO KEEP MOST OF THE INSTABILITY SOUTH AND WEST OF OUR CWA.
WOULD EXPECT DAILY ISOLATED TO SCATTERED STORM DEVELOPMENT IN THE
WESTERN PLAINS WHERE THE SOUTHEASTERLY UPSLOPE FLOW...CONVERGENCE
AND INSTABILITY ARE MAXIMIZED. HOWEVER THINK MOST OF THAT ACTIVITY
WILL STAY OUT OF OUR AREA. THE EXCEPTION COULD BE IN THE FAR
SOUTHWEST CORNER OF OUR CWA...TOWARDS GREGORY COUNTY...WHICH IS
CLOSE ENOUGH TO THIS ACTION TO WARRANT A LOW CHANCE POP EACH DAY AND
NIGHT. NAM IS A BIT MORE AGGRESSIVE WITH CONVECTION ALONG THE
MISSOURI RIVER AND WEST OF THE JAMES RIVER MONDAY NIGHT INTO
TUESDAY. IT IS FURTHER EAST WITH THE 850 MB BOUNDARY...ALLOWING
CONVERGENCE AND INSTABILITY TO CREEP FURTHER NORTHEAST. BUT SINCE IT
IS A PRETTY BIG OUTLIER AT THIS TIME...WILL STICK CLOSER TO THE
ECMWF AND GFS SOLUTIONS. LOWS MONDAY NIGHT AND TUESDAY NIGHT
DEPENDENT ON CLOUD COVER...BUT AT THIS POINT THINKING WE SEE ENOUGH
CLEARING TO GET SOME COOL LOWS EAST OF THE JAMES RIVER...WITH LOW
AND MID 50S EXPECTED. HIGHS TUESDAY AND WEDNESDAY WILL STAY BELOW
NORMAL...WITH MID AND UPPER 70S COMMON.
BY WEDNESDAY NIGHT THE RIDGING BEGINS TO PUSH NORTHEAST CLOSER TO
THE AREA AS OUR HIGH PRESSURE MOVES OFF TO THE EAST. THIS WILL ALLOW
LOW LEVEL SOUTHEASTERLY WINDS TO MOVE FURTHER INTO THE
AREA...ALLOWING FOR A SLOW INCREASE IN INSTABILITY. THIS WILL ALSO
ALLOW FOR NIGHTLY INCREASES IN THE LOW LEVEL JET WHICH SHOULD ACT TO
HELP INCREASE OUR PRECIP CHANCES. WEDNESDAY NIGHT MAY SEE SOME
ACTIVITY MAKE IT CLOSE TO INTERSTATE 29...AND BY THURSDAY INTO
THURSDAY NIGHT WE MIGHT BE ABLE TO GET SOME CONVECTION ACROSS THE
CWA. INSTABILITY STILL ON THE LOW SIDE AND FORCING NOT THAT
IMPRESSIVE...SO ONLY LOW CHANCE POPS WARRANTED AT THIS TIME. AS THE
RIDGING CONTINUES TO SLOWLY BUILD IN...STARTING TO LOOK LIKE FRIDAY
INTO THE WEEKEND WILL STAY DRY...WITH A WARMING TREND EACH DAY.
THURSDAY WILL SEE MID 70S TO NEAR 80...WITH READINGS NEAR 80 TO 85
OVER THE WEEKEND.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 611 PM CDT SUN AUG 11 2013
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD AS
HIGH PRESSURE BUILDS INTO THE REGION BEHIND A DEPARTING FRONT. THE
EXCEPTION WILL BE SOME PATCHY MVFR/IFR VSBYS WITH RADIATIONAL FOG
LATE TONIGHT/EARLY MONDAY MORNING DUE TO LIGHT WINDS...CLEARING
SKIES...AND RESIDUAL MOISTURE FROM RECENT RAINFALL.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
242 PM MDT SAT AUG 10 2013
.SHORT TERM...THIS EVENING THROUGH SUNDAY NIGHT
ISSUED AT 119 PM MDT SAT AUG 10 2013
CURRENT SURFACE ANALYSIS PLACES HIGH OVER THE MIDWEST WITH LOW
OVER THE CENTRAL ROCKIES WHILE FRONTAL BOUNDARY CONTINUES TO
STRETCH ALONG THE NEBRASKA/SOUTH DAKOTA BORDER. UPPER LEVEL
ANALYSIS PLACES LOW SPINNING ALONG THE NRN CALIFORNIA/SRN OREGON
COAST WHILE NEGATIVELY TILTED RIDGE STRETCHES FROM THE SRN PLAINS
UP INTO THE NRN ROCKIES. SERIES OF SHORT WAVES CONTINUE TO LIFT
THROUGH THE RIDGE.
FOR THE REST OF THIS AFTERNOON INTO THIS EVENING...NEXT WAVE
PUSHING THROUGH CENTRAL WYOMING CONTINUES IT SLOW APPROACH TOWARDS
THE AREA WHICH WILL RESULT IN SOME STORMS DEVELOPING. THIS WAVE
APPEARS TO BE MORE SUBTLE THAN LAST NIGHTS...SO EXPECT STORMS TO
BE MORE ISOLD/SCT. THERE IS A SEVERE CONCERN...THOUGH...AS ~30-40
KTS 0-6KM BULK SHEAR WILL IN PLACE COMBINED WITH CAPE VALUES ~1-2
KJ/KG. THEREFORE WILL HAVE TO KEEP AN EYE ON ANY STORMS THAT DO
DEVELOP. ALSO...IF AFOREMENTIONED SFC BOUNDARY CREEPS A BIT MORE
NORTH MAY HAVE TO KEEP AN EYE OF STORMS THAT MOVE ALONG IT FOR A
BRIEF TORNADIC THREAT...THOUGH THIS DOES REMAIN QUITE LOW. MOST
STORMS SHOULD DISSIPATE BY LATE TONIGHT BUT HAVE KEEP SOME LOW
POPS IN LATE AS HIGH RES MODELS HAVE BEEN CONSISTENT WITH THE
POSSIBILITY OF A FEW STORMS LOITERING AROUND. GIVEN THE PERSISTENT
PATTERN OF LATE NIGHT CONVECTION HAVE A HARD TIME RULING THIS OUT.
WITH THE AMPLE LOW LEVEL MOISTURE IN PLACE COMBINED WITH THE LIGHT
EASTERLY FLOW...EXPECT SOME PATCHY FOG MAY DEVELOP LATE ALONG THE
EASTERN FLANKS OF THE BLACK HILLS INTO THE PLAINS A BIT.
ON SUNDAY...AFOREMENTIONED FOG SHOULD DISSIPATE EARLY.
OTHERWISE...QUIET CONDITIONS ARE EXPECTED UNTIL AFTERNOON WHEN THE
NEXT IN OUR LITTLE PARADE OF SHORT WAVES SLIDE THROUGH THE
PERSISTENT PATTERN. AGAIN...SEVERE THREAT REMAINS WITH INCREASING
INSTABILITY THOUGH SHEAR WILL BE MODEST. MAIN CONCERN MAY BE NEAR
SFC BOUNDARY TOWARDS THE NEBRASKA BORDER.
&&
.LONG TERM...MONDAY THROUGH SATURDAY
ISSUED AT 119 PM MDT SAT AUG 10 2013
MEAN WESTERN NOAM RIDING TO REMAIN IN THE PERIOD...WITH
DOWNSTREAM NEGATIVE HEIGHT ANOMALIES LINGERING IN EASTERN NOAM. NE
PAC TROUGHING WILL SUPPORT NUMEROUS SUBTLE IMPULSES IN THE
FLOW...WITH A MORE SUBSTANTIAL WAVE POSSIBLE TOWARD THE END OF NEXT
WEEK...SUPPORTING AN EASTERN BIAS TO THE WESTERN CONUS RIDGE.
MEANWHILE A NORTHERN STREAM UPPER TROUGH WILL GRAZE THE REGION
MONDAY...SUPPORTING A PSEUDO BACKDOOR FRONT INTO THE AREA...STALLING
OVER THE WESTERN HALF OF THE AREA...AND PROVIDING A PATHWAY FOR
PERTURBED WNW FLOW THROUGH MID WEEK. MEAN ENSEMBLES AS WELL AS THE
ECMWF ARE SUPPORTING A REMOVAL OF THE HIGH LATITUDE BLOCKING RIDGE
WITH MORE PROGRESSIVE TENDENCIES TO THE FLOW OVER WESTERN CANADA
TOWARD THE END OF THE WEEK. HOWEVER...ECMWF AND GFS DETERMINISTIC
RUNS SUPPORT ANOTHER ROUND OF STAUNCH WESTERN NOAM RIDGING MUCH MORE
PRONOUNCED THAN THE CURRENT WESTERN NOAM RIDGE...WITH NEGATIVE
HEIGHT TENDENCIES OVER SE CANADA ONCE AGAIN. IF LL MOISTURE REMAINS
AS IN THE ECMWF PROGS...AN ACTIVE PATTERN COULD CERTAINLY RETURN TO
THE REGION...ESP IF DOWNSTREAM BLOCKING DEVELOPS ONCE AGAIN.
RETAINED LOW PRECIP CHANCES THROUGH THUR...CONTINUED WITH A DRY
FRIDAY AND SAT GIVEN FLOW RE-ADJUSTMENT AND UPPER RIDGING/WARMING.
TEMPS WILL REMAIN AROUND SEASONAL NORMS THROUGH MID WEEK WITH A
WARMING TREND INTO NEXT WEEKEND AS THE UPPER RIDGE SHIFTS EAST.
&&
.AVIATION...FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON
ISSUED AT 119 PM MDT SAT AUG 10 2013
WEAK IMPULSE COUPLED WITH DIURNAL HEATING WILL SUPPORT
SCT SHRA/TS ACTIVITY OVER THE BLACK HILLS THIS AFTERNOON...AND THE
REMAINDER OF NE WY AND WESTERN SD LATE THIS AFTERNOON/EVENING. HAVE
OPTED FOR JUST A VCTS MENTION AT THE TERMINALS GIVEN EXPECTED LOW
COVERAGE. SCT MVFR CIGS MAY PERSIST INTO EARLY THIS AFTERNOON OVER
THE EASTERN BH FOOTHILLS...GIVEN UPSLOPE FLOW WITH A MOIST BL. HAVE
ADDED A TEMPO AT KRAP FOR THIS. OTHERWISE...IFR CIGS ARE POSSIBLE
TOWARD THE END OF THE PERIOD...AFT 10Z SUNDAY. THERE IS A PRETTY
STRONG SIGNAL FOR LOW STRATUS DEVELOPMENT OVER MUCH OF WRN/CNTRL SD
AS MOIST UPSLOPE FLOW PERSISTS. THIS IS HINTED AT BOTH IN THE SREF
AND MET GUIDANCE. HAVE TRENDED TO SCT IFR CIGS AT RAP FOR NOW.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...77
LONG TERM...JC
AVIATION...JC
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1156 PM CDT FRI AUG 9 2013
.UPDATE...FOR 06Z AVIATION.
&&
.AVIATION...06Z TAF DISCUSSION.
LONE SHOWER IN MIDDLE TENNESSEE FINALLY COMING TO AN END NEAR
ISSUANCE TIME. WARM FRONT REMAINS DRAPED ACROSS NORTHERN MIDDLE
PORTIONS OF THE STATE AND HAS BEEN THE FOCUS FOR CONVECTION THIS
EVENING. THIS WILL CONTINUE TO BE THE CASE...HELPING TO SPARK
MORE SH/TS BY LATE MORNING...AS WELL AS HELP TO DROP FLIGHT
CATEGORIES LATER TONIGHT. SHOULD SEE IFR CONDITIONS AT
CSV/CKV...WITH INCREASE BACK TO VFR BY LATE MORNING. WINDS WILL
ACTUALLY SHIFT TO THE NW...AND IN SOME CASES NORTHERLY...AS THE
FRONT SAGS INTO THE SOUTHERN PORTIONS OF THE STATE ON SATURDAY.
UNGER
&&
.PREV DISCUSSION... /ISSUED 819 PM CDT FRI AUG 9 2013/
UPDATE...SCATTERED CONVECTION HAS BEEN TRENDING DOWNWARD IN
COVERAGE AND INTENSITY...AND SEE NO REASON FOR THIS TO CHANGE
THROUGH LATE EVENING. HAVE LOWERED POPS AND QPF ACROSS THE AREA
TO INDICATE "SCATTERED" THUNDERSTORMS OVERNIGHT AND AVERAGE
RAINFALL AMOUNTS UNDER ONE QUARTER INCH. OF COURSE...WITH THE VERY
MOIST AIR MASS STILL IN PLACE...LOCALIZED HEAVY RAINFALL IS STILL
A POSSIBILITY. SHORT RANGE MODELS INCLUDING LATEST HRRR SHOW ONLY
SCATTERED AT BEST OVERNIGHT...BUT DO HINT AT INCREASING ACTIVITY
TOWARD DAYBREAK COMING IN FROM THE NORTHWEST AS THE QUASI
STATIONARY FRONT DIPS A LITTLE CLOSER AND A SHEARING UPPER WAVE
APPROACHES. STILL EXPECT ACTIVITY TO BECOME MORE WIDESPREAD ON
SATURDAY WITH FRONT OVER THE REGION.
13
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
27
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
247 PM CDT SAT AUG 10 2013
.DISCUSSION...
A weak cold front that had moved into the region yesterday had a bit
of a push this morning from overnight convection and is now stalled
from the Big Bend eastward into central TX. The NAM and RUC have
convection developing along southern portions of the boundary and
rapidly developing CU marking this boundary can be seen on visible
satellite. A few showers already showing up across the southeastern
zones and went ahead and added isolated mention to this area for the
remainder of today. Otherwise, easterly upslope flow and a
persistent theta e ridge may result in showers and thunderstorms
across the higher terrain and SE New Mexico this evening and could
linger overnight with upper level weaknesses moving through New
Mexico on the western periphery of the upper ridge. Will keep
chance POPs going across these areas during this time.
The NAM has convection developing once again Sunday across much of
the region. It is the most aggressive with QPF output and will only
include slight chance across most of the area. Think highest chances
will remain across SE NM as another disturbance moves east through
the TX Panhandle Sunday afternoon. Rain chances will continue into
the overnight hours mainly across the Permian Basin. PWATs will
remain higher through the weekend so will keep mention of potential
heavy rainfall. Monday, the upper ridge begins to move back west and
rain chances decrease for our area for at least a few days. In
general, temperatures will remain cooler than what we experienced
last week.
By mid week, the upper ridge will be centered over the Desert
Southwest leaving west TX and SE NM under weak NW flow aloft. Hard
to tell if any disturbances moving SE in the flow aloft will affect
us just yet but will keep an eye on it. Models are hanging onto a
weak cold front sagging into the region Wednesday afternoon/evening,
increasing rain chances across the northern PB through Thursday
morning. For now, will hold off on increasing POPs in the grids.
Expect temperatures to cool toward normals for the end of the work
week.
&&
.PRELIMINARY POINT TEMPS/POPS...
ANDREWS TX 71 94 73 95 / 30 10 20 10
BIG SPRING TX 73 96 74 96 / 20 10 20 10
CARLSBAD NM 69 91 72 95 / 30 20 10 10
DRYDEN TX 77 99 76 98 / 20 20 10 10
FORT STOCKTON TX 72 95 72 96 / 20 20 10 10
GUADALUPE PASS TX 65 87 67 89 / 30 20 10 10
HOBBS NM 67 89 71 92 / 30 20 20 10
MARFA TX 62 86 63 86 / 30 20 10 10
MIDLAND INTL AIRPORT TX 72 95 73 96 / 20 10 20 10
ODESSA TX 73 95 74 95 / 20 10 20 10
WINK TX 74 96 75 98 / 30 20 20 10
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...NONE.
TX...NONE.
&&
$$
44/27
AREA FORECAST DISCUSSION
NWS BROWNSVILLE TX
1219 PM CDT SAT AUG 10 2013
.DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
&&
.AVIATION...HRL AIRPORT WILL BE IN A FAVORED AREA FOR NEW
SHOWER/THUNDERSTORM DEVELOPMENT FOR THE NEXT FEW HOURS. AREA OF
CONVECTIVE ACTIVITY WILL MOVE TOWARDS MFE AND PERSIST FOR ANOTHER
2 TO 3 HOURS. BROWNSVILLE IS LESS LIKELY TO SEE NEW THUNDERSTORM
DEVELOPMENT...BUT SUN WILL LIKELY RETURN LATER AND MAY AID IN
DEVELOPING NEW ACTIVITY IN 2 TO 4 HOURS.
MAIN BAND OF DEEPER CONVECTION/15 TO 20 MINUTES OF MVFR TO IFR VIS/
WILL PERSIST BETWEEN THE 77 AND 281 CORRIDOR AND SLOWLY SHIFT
WESTWARD THROUGH MID TO LATE AFTERNOON. OFF AND ON SHOWERS WILL BE
POSSIBLE THROUGHOUT THE ENTIRE AREA THROUGH THE AFTERNOON.
STRONGER WIND GUSTS WILL BE POSSIBLE IN THE WESTERN 3 COUNTIES OF
DEEP SOUTH TEXAS WITH ANY THUNDERSTORMS.
A GENERAL DOWNWARD TREND IS EXPECTED THIS EVENING WITH MORE
ISOLATED SHOWERS OVERNIGHT BEFORE ANOTHER ROUND OF CONVECTION
BEGINS DEVELOPING BY 9 TO 10 AM SUNDAY MORNING. WINDS SHOULD BE
LIGHT TO MODERATE OUT OF THE EAST TO NORTHEAST. OUTSIDE OF
THUNDERSTORMS EXPECTING PREVAILING VFR CONDITIONS THROUGH THE TAF
PERIOD. /68-JGG/
&&
.PREV DISCUSSION... /ISSUED 1206 PM CDT SAT AUG 10 2013/
DISCUSSION...RADAR SHOWS SCATTERED TO NUMEROUS CONVECTIVE CELLS
ALONG AND JUST WEST OF A WEAK CONVERGENCE ZONE SET UP JUST EAST OF
HIGHWAY 77 WHERE SOMEWHAT STRONGER EASTERLY ONSHORE WINDS MET
LIGHTER WINDS OVER LAND. EXPECTING THE CELLS THAT HAVE INITIATED
TO CONTINUE MOVING JUST SOUTH OF WEST AT AROUND 15 MPH WITH NEW
DEVELOPMENT ALONG THE BOUNDARY FOR ANOTHER FEW HOURS. AN OUTFLOW
BOUNDARY ALSO IS EVIDENT BETWEEN HARLINGEN AND BROWNSVILLE...AND
THE REMNANT OF PREVIOUS CONVECTION OVER THE GULF SHOWS WEAK
CONVERGENCE ON DOPPLER VELOCITIES IN A WEAK MCV TYPE FORM AS IT
MOVES SLOWLY WEST ONSHORE NEAR SOUTH PADRE ISLAND. THIS FEATURE COULD
INITIATE NEW CONVECTION AS IT MOVES INTO MORE UNSTABLE AIR INLAND.
COLUMN CONTINUES TO SATURATE FURTHER AMID DEEP EASTERLY ONSHORE
WINDS...INCREASING CLOUD COVER FROM CU AND ANVIL DEBRIS IS SLOWING
THE INCREASE OF HEATING AND INSTABILITY BUT EXPECT THE BEST
CONVERGENCE TO SLOWLY MOVE WEST THROUGH THE DAY MOVING TO NEAR
HIGHWAY 281 BY 2 TO 3 PM AND A CHANCE CONTINUES FOR CONVECTION TO
MOVE WEST INTO STARR/ZAPATA/JIM HOGG COUNTY LATER THIS AFTERNOON.
TWEAKED NEAR TERM TEMP GRIDS/AFTERNOON MAX TS WHERE CONVECTION WAS
PLAYING A ROLE AND MADE MINOR TIMING/POP ADJUSTMENTS TO THE
FORECAST. /68-JGG/
PREV DISCUSSION... /ISSUED 933 AM CDT SAT AUG 10 2013/
DISCUSSION...MORNING SOUNDING AND SATELLITE DERIVED PRECIPITABLE
WATER ESTIMATES CONTINUE TO INDICATE A VERY SATURATED
AIRMASS...ASSOCIATED WITH A TROPICAL WAVE MOVING WESTWARD ACROSS
THE WEST CENTRAL GULF HAS MOVED INTO THE AREA. RAP AND MODIFIED
MORNING FORECAST SOUNDINGS INDICATE WE ARE APPROACHING CONVECTIVE
TEMPERATURE WITH LITTLE LOWER TROPOSPHERIC WARMING EXPECTED DUE TO
THE SATURATED AIRMASS AND CU STREAKS AND CONVERGENCE ZONES ARE
BECOMING READILY APPARENT ON VISIBLE SATELLITE IMAGERY. THE TWO
STRONGEST ZONES ARE ASSOCIATED WITH THE SEABREEZE IN EASTERN
CAMERON AND WILLACY COUNTY...AND DEVELOPING SHOWER ACTIVITY NEAR
WESLACO. A GENERALLY DIFFLUENT UPPER LEVEL PATTERN JUST OFFSHORE
IS PRODUCING WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS OVER OUR
COASTAL WATERS FOCUSED ALONG WEAK SURFACE TROUGHING MOVING SLOWLY
WESTWARD UNDER THIS FEATURE.
ALL THAT BEING SAID EXPECTING CONVECTIVE DEVELOPMENT TO INCREASE
MARKEDLY OVER THE NEXT TWO TO THREE HOURS WITH SCATTERED TO
NUMEROUS SHOWERS AND STORMS DEVELOPING...POSSIBLY BECOMING
WIDESPREAD IF THE MORE FAVORABLE UPPER LEVEL ENVIRONMENT OVER THE
GULF MOVES ONSHORE. HOWEVER NEAR AND SHORT TERM GUIDANCE HAS BEEN
CONSISTENTLY SHOWING WEAKENING OF THIS FEATURE AS IT MOVES INLAND.
NEVERTHELESS THE CURRENT THERMODYNAMIC AND MOISTURE PROFILE WILL
PROVIDE SHRA/TSRA. THE SHOWERS SHOULD GREATLY OUTNUMBER THE STORMS
BUT THERE WILL PROBABLY BE A FEW RUMBLES OF THUNDER.
THE STRONGEST CELLS WILL PRODUCE EXCEPTIONALLY EFFICIENT RAINFALL
RATES...ON THE ORDER OF TWO TO THREE INCHES PER HOUR AS THEY MOVE
WEST AT AROUND 15 MPH. MOST CONVECTION WILL PROBABLY BE LESS
INTENSE HOWEVER...AND PRODUCE RAINFALL RATES CLOSER TO ONE HALF TO
TWO INCHES PER HOUR. TOTAL ACCUMULATIONS AT ANY ONE LOCATION WILL
LIKELY BE LESS AS THE ACTIVITY MOVES SLOWLY WESTWARD. THE GRIDDED
FORECASTS SHOW THE ANTICIPATED EVOLUTION WELL AND NO SIGNIFICANT
CHANGES ARE PLANNED FOR NOW. /68-JGG/
PREV DISCUSSION... /ISSUED 634 AM CDT SAT AUG 10 2013/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
AVIATION...EXPECTING CONVECTION TO DEVELOP LATER THIS MORNING
FIRST ALONG THE COAST AND THEN MOVE INLAND THIS AFTERNOON.
EXPECTING BEST CHANCES AND COVERAGE BETWEEN 16-21Z IN THE EAST
AND 18-23Z IN THE CENTRAL AND WEST. VFR CONDITIONS TO PREVAIL
OUTSIDE OF THE CONVECTION WITH TEMPORARY MVFR CIGS VSBY IN AND
NEAR THE SCATTERED THUNDERSTORMS AND SHOWERS. MOISTURE VALUES TO
REMAIN RATHER HIGH SO EXPECT A LAYER OF STRATUS TO DEVELOP
OVERNIGHT AOA MVFR. SURFACE WIND TO REMAIN LIGHT FROM A GENERAL
EAST DIRECTION.
PREV DISCUSSION... /ISSUED 403 AM CDT SAT AUG 10 2013/
SHORT TERM /NOW THROUGH SUNDAY/...SATELLITE AND RADAR LOOPS
INDICATE MOISTURE IS BEGINNING TO MOVE INTO COASTAL WATERS.
SHOWERS AND AN ISOLATED THUNDERSTORM OR TWO HAVE BEEN MOVING INTO
NORTHEAST MEXICO SINCE 1AM IN ADVANCE OF THE LARGE SCALE MID TO
UPPER LEVEL TROUGH CENTERED JUST NORTH OF THE YUCATAN.
FOR TODAY...LOOKING AT SHOWERS THIS MORNING TO FAVOR THE IMMEDIATE
COASTAL AREAS AND THE GULF WATERS. NOT UNTIL THE MOISTURE COLUMN
BECOMES NEARLY SATURATED AROUND OR AFTER 18Z AND PWATS EXCEED 2.25
INCHES WILL WE SEE CONVECTION DEVELOP FARTHER INLAND. A DEEPENING
EASTERLY FLOW TO ENHANCE SURFACE CONVERGENCE ALONG THE SEABREEZE AND
DESTABILIZATION OF THE ATMOSPHERE AS SURFACE HEATING GETS GOING THIS
MORNING BEFORE THE CLOUDS INCREASE TO GIVE THE LOWER AND MID VALLEY
THE BEST AND HIGHEST CHANCE OF RAIN IN LONG WHILE. INHERITED
FORECAST LOOKS GOOD AND REMAINS IN LINE WITH LATEST GUIDANCE. DID
NOT MENTION HEAVY RAIN IN THE FORECAST WITH THE ANTICIPATION OF
CELLS TO MOVE STEADILY EAST TO WEST UNDER A 15 TO 20 KNOT MID LAYER
FLOW. SURFACE TROUGHING LOOKS TO REMAIN JUST OFFSHORE ALONG WITH
UPPER DIVERGENCE KEEPING CONVECTION INITIATION EAST OF THE COAST
WITH THE HEAVIEST AND MOST CONCENTRATED AREA OF RAIN OFFSHORE.
WITH THIS SAID POCKETS OF HEAVY RAIN ARE STILL POSSIBLE INLAND...AS
MOISTURE INCREASES...AND ANY WESTWARD SHIFT OF THE TROUGH COULD PUSH
THE HEAVIER RAIN INLAND. TEMPERATURES TO CLIMB QUICKLY WITH SUNNY
CONDITIONS EARLY ON ESPECIALLY OUT WEST. THEN THEY ARE LIKELY TO
FALL AS RAIN DEVELOPS.
TONIGHT...UPPER TROUGH CONTINUES TO TRACK WESTWARD. CONVECTION TO
WANE INLAND AS STABILIZATION OCCURS WITH WESTERN AREAS SEEING SOME
RAIN LINGER PASS SUNSET. CONVECTION TO REFIRE OVERNIGHT OFFSHORE AS
THE UPPER TROUGH AXIS NEARS THE COAST AND NOCTURNAL DESTABILIZATION
OCCURS. SOME SHOWERS TO WORK THEIR WAY INLAND ACROSS THE LOWER
VALLEY AS THE SURFACE TROUGH NEARS THE COAST.
SUNDAY...ANOTHER GOOD CHANCE OF SHOWERS AND THUNDERSTORMS AS THE
UPPER TROUGH AXIS MOVES OVERHEAD. SOUTH TEXAS WILL BE ON THE
NORTHERN PERIPHERY OF THE TROUGH WITH BETTER CONVERGENCE AND
INSTABILITY SHIFTING FARTHER TO THE SOUTH WITH THE CENTER OF THE
TROUGH. IN ANY CASE...MOISTURE VALUES AND DEEP EASTERLY TO KEEP RAIN
CHANCES RATHER HIGH CONSIDERING THE LAST TWO WEEKS. FORECAST REMAINS
IN RANGE OF MAV/GFS GUIDANCE WITH MET/NAM LOOKING TO HIGH WITH A
MORE ROBUST SURFACE DEVELOPMENT WHICH DOES ON LOOK REASONABLE.
DAYTIME DESTABILIZATION TO TAKE PLACE BUT COULD BE LIMITED WITH
MULTI LAYERED CLOUD COVER LIMITED SURFACE HEATING. WITH THIS SAID
TEMPERATURES TO BE 7 TO 10 DEGREES COOLER THEN THE EXTREME HEAT THAT
WE HAVE EXPERIENCED.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...BY SUNDAY NIGHT THE
INVERTED TROUGH AXIS WILL BE TO THE WEST OF THE VALLEY. MOISTURE
WILL STILL BE SUBSTANTIAL...WITH PW VALUES BEGINNING THE PERIOD AT
2 INCHES...SLOWLY FALLING TO 1.6 BY TUESDAY MORNING. WITH THE
ABUNDANCE OF MOISTURE STILL PRESENT...STILL FEEL THAT SEABREEZE
SHOWERS WILL SPARK DURING THE AFTERNOON MONDAY...ALBEIT NOT AS
WIDESPREAD AS OVER THE WEEKEND. H5 RIDGE REBUILDS ACROSS TEXAS IN
THE WAKE OF THE TROUGH ON TUESDAY...WITH PW VALUES AOB 1.5 INCHES
THROUGH THE REST OF THE WEEK. THIS PRECLUDES THE CHANCE OF ANY
SEABREEZE ACTIVITY. TEMPERATURES WILL START TO RECOVER ON
MONDAY...JUMPING BACK INTO THE UPPER 90S AND LOW 100S. A GRADUAL
RETURN TO WIDESPREAD 100 DEGREE TEMPERATURES WILL CONTINUE THROUGH
THE REST OF THE WEEK.
MARINE...
NOW THROUGH SUNDAY...THE APPROACH OF THE UPPER TROUGH AND A
SURFACE TROUGH TO KEEP AN EAST WIND AT LIGHT TO MODERATE LEVELS
TODAY THROUGH SUNDAY. SHOWERS AND THUNDERSTORMS TO INCREASE IN
COVERAGE AND INTENSITY THROUGH THE PERIOD PRODUCING A SLIGHTLY
HIGHER SEA TONIGHT AND SUNDAY. NO SMALL CRAFT ADVISORIES ARE
ANTICIPATED.
MONDAY NIGHT THROUGH THURSDAY...WEAK GRADIENT WILL BE THE RULE
ACROSS THE MARINE ZONES THROUGH THE WEEK...WITH ONSHORE FLOW OF 10
TO 15 KNOTS EXPECTED EACH DAY. SEAS WILL GENERALLY RUN 2 TO 4
FEET...APPROACHING 5 FEET INITIALLY MONDAY NIGHT INTO TUESDAY. NO
ADVISORIES ARE EXPECTED.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV
68/67
AREA FORECAST DISCUSSION...UPDATED
NWS BROWNSVILLE TX
1206 PM CDT SAT AUG 10 2013
.DISCUSSION...RADAR SHOWS SCATTERED TO NUMEROUS CONVECTIVE CELLS
ALONG AND JUST WEST OF A WEAK CONVERGENCE ZONE SET UP JUST EAST OF
HIGHWAY 77 WHERE SOMEWHAT STRONGER EASTERLY ONSHORE WINDS MET
LIGHTER WINDS OVER LAND. EXPECTING THE CELLS THAT HAVE INITIATED
TO CONTINUE MOVING JUST SOUTH OF WEST AT AROUND 15 MPH WITH NEW
DEVELOPMENT ALONG THE BOUNDARY FOR ANOTHER FEW HOURS. AN OUTFLOW
BOUNDARY ALSO IS EVIDENT BETWEEN HARLINGEN AND BROWNSVILLE...AND
THE REMNANT OF PREVIOUS CONVECTION OVER THE GULF SHOWS WEAK
CONVERGENCE ON DOPPLER VELOCITIES IN A WEAK MCV TYPE FORM AS IT
MOVES SLOWLY WEST ONSHORE NEAR SOUTH PADRE ISLAND. THIS FEATURE COULD
INITIATE NEW CONVECTION AS IT MOVES INTO MORE UNSTABLE AIR INLAND.
COLUMN CONTINUES TO SATURATE FURTHER AMID DEEP EASTERLY ONSHORE
WINDS...INCREASING CLOUD COVER FROM CU AND ANVIL DEBRIS IS SLOWING
THE INCREASE OF HEATING AND INSTABILITY BUT EXPECT THE BEST
CONVERGENCE TO SLOWLY MOVE WEST THROUGH THE DAY MOVING TO NEAR
HIGHWAY 281 BY 2 TO 3 PM AND A CHANCE CONTINUES FOR CONVECTION TO
MOVE WEST INTO STARR/ZAPATA/JIM HOGG COUNTY LATER THIS AFTERNOON.
TWEAKED NEAR TERM TEMP GRIDS/AFTERNOON MAX TS WHERE CONVECTION WAS
PLAYING A ROLE AND MADE MINOR TIMING/POP ADJUSTMENTS TO THE
FORECAST. /68-JGG/
&&
.PREV DISCUSSION... /ISSUED 933 AM CDT SAT AUG 10 2013/
DISCUSSION...MORNING SOUNDING AND SATELLITE DERIVED PRECIPITABLE
WATER ESTIMATES CONTINUE TO INDICATE A VERY SATURATED
AIRMASS...ASSOCIATED WITH A TROPICAL WAVE MOVING WESTWARD ACROSS
THE WEST CENTRAL GULF HAS MOVED INTO THE AREA. RAP AND MODIFIED
MORNING FORECAST SOUNDINGS INDICATE WE ARE APPROACHING CONVECTIVE
TEMPERATURE WITH LITTLE LOWER TROPOSPHERIC WARMING EXPECTED DUE TO
THE SATURATED AIRMASS AND CU STREAKS AND CONVERGENCE ZONES ARE
BECOMING READILY APPARENT ON VISIBLE SATELLITE IMAGERY. THE TWO
STRONGEST ZONES ARE ASSOCIATED WITH THE SEABREEZE IN EASTERN
CAMERON AND WILLACY COUNTY...AND DEVELOPING SHOWER ACTIVITY NEAR
WESLACO. A GENERALLY DIFFLUENT UPPER LEVEL PATTERN JUST OFFSHORE
IS PRODUCING WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS OVER OUR
COASTAL WATERS FOCUSED ALONG WEAK SURFACE TROUGHING MOVING SLOWLY
WESTWARD UNDER THIS FEATURE.
ALL THAT BEING SAID EXPECTING CONVECTIVE DEVELOPMENT TO INCREASE
MARKEDLY OVER THE NEXT TWO TO THREE HOURS WITH SCATTERED TO
NUMEROUS SHOWERS AND STORMS DEVELOPING...POSSIBLY BECOMING
WIDESPREAD IF THE MORE FAVORABLE UPPER LEVEL ENVIRONMENT OVER THE
GULF MOVES ONSHORE. HOWEVER NEAR AND SHORT TERM GUIDANCE HAS BEEN
CONSISTENTLY SHOWING WEAKENING OF THIS FEATURE AS IT MOVES INLAND.
NEVERTHELESS THE CURRENT THERMODYNAMIC AND MOISTURE PROFILE WILL
PROVIDE SHRA/TSRA. THE SHOWERS SHOULD GREATLY OUTNUMBER THE STORMS
BUT THERE WILL PROBABLY BE A FEW RUMBLES OF THUNDER.
THE STRONGEST CELLS WILL PRODUCE EXCEPTIONALLY EFFICIENT RAINFALL
RATES...ON THE ORDER OF TWO TO THREE INCHES PER HOUR AS THEY MOVE
WEST AT AROUND 15 MPH. MOST CONVECTION WILL PROBABLY BE LESS
INTENSE HOWEVER...AND PRODUCE RAINFALL RATES CLOSER TO ONE HALF TO
TWO INCHES PER HOUR. TOTAL ACCUMULATIONS AT ANY ONE LOCATION WILL
LIKELY BE LESS AS THE ACTIVITY MOVES SLOWLY WESTWARD. THE GRIDDED
FORECASTS SHOW THE ANTICIPATED EVOLUTION WELL AND NO SIGNIFICANT
CHANGES ARE PLANNED FOR NOW. /68-JGG/
PREV DISCUSSION... /ISSUED 634 AM CDT SAT AUG 10 2013/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
AVIATION...EXPECTING CONVECTION TO DEVELOP LATER THIS MORNING
FIRST ALONG THE COAST AND THEN MOVE INLAND THIS AFTERNOON.
EXPECTING BEST CHANCES AND COVERAGE BETWEEN 16-21Z IN THE EAST
AND 18-23Z IN THE CENTRAL AND WEST. VFR CONDITIONS TO PREVAIL
OUTSIDE OF THE CONVECTION WITH TEMPORARY MVFR CIGS VSBY IN AND
NEAR THE SCATTERED THUNDERSTORMS AND SHOWERS. MOISTURE VALUES TO
REMAIN RATHER HIGH SO EXPECT A LAYER OF STRATUS TO DEVELOP
OVERNIGHT AOA MVFR. SURFACE WIND TO REMAIN LIGHT FROM A GENERAL
EAST DIRECTION.
PREV DISCUSSION... /ISSUED 403 AM CDT SAT AUG 10 2013/
SHORT TERM /NOW THROUGH SUNDAY/...SATELLITE AND RADAR LOOPS
INDICATE MOISTURE IS BEGINNING TO MOVE INTO COASTAL WATERS.
SHOWERS AND AN ISOLATED THUNDERSTORM OR TWO HAVE BEEN MOVING INTO
NORTHEAST MEXICO SINCE 1AM IN ADVANCE OF THE LARGE SCALE MID TO
UPPER LEVEL TROUGH CENTERED JUST NORTH OF THE YUCATAN.
FOR TODAY...LOOKING AT SHOWERS THIS MORNING TO FAVOR THE IMMEDIATE
COASTAL AREAS AND THE GULF WATERS. NOT UNTIL THE MOISTURE COLUMN
BECOMES NEARLY SATURATED AROUND OR AFTER 18Z AND PWATS EXCEED 2.25
INCHES WILL WE SEE CONVECTION DEVELOP FARTHER INLAND. A DEEPENING
EASTERLY FLOW TO ENHANCE SURFACE CONVERGENCE ALONG THE SEABREEZE AND
DESTABILIZATION OF THE ATMOSPHERE AS SURFACE HEATING GETS GOING THIS
MORNING BEFORE THE CLOUDS INCREASE TO GIVE THE LOWER AND MID VALLEY
THE BEST AND HIGHEST CHANCE OF RAIN IN LONG WHILE. INHERITED
FORECAST LOOKS GOOD AND REMAINS IN LINE WITH LATEST GUIDANCE. DID
NOT MENTION HEAVY RAIN IN THE FORECAST WITH THE ANTICIPATION OF
CELLS TO MOVE STEADILY EAST TO WEST UNDER A 15 TO 20 KNOT MID LAYER
FLOW. SURFACE TROUGHING LOOKS TO REMAIN JUST OFFSHORE ALONG WITH
UPPER DIVERGENCE KEEPING CONVECTION INITIATION EAST OF THE COAST
WITH THE HEAVIEST AND MOST CONCENTRATED AREA OF RAIN OFFSHORE.
WITH THIS SAID POCKETS OF HEAVY RAIN ARE STILL POSSIBLE INLAND...AS
MOISTURE INCREASES...AND ANY WESTWARD SHIFT OF THE TROUGH COULD PUSH
THE HEAVIER RAIN INLAND. TEMPERATURES TO CLIMB QUICKLY WITH SUNNY
CONDITIONS EARLY ON ESPECIALLY OUT WEST. THEN THEY ARE LIKELY TO
FALL AS RAIN DEVELOPS.
TONIGHT...UPPER TROUGH CONTINUES TO TRACK WESTWARD. CONVECTION TO
WANE INLAND AS STABILIZATION OCCURS WITH WESTERN AREAS SEEING SOME
RAIN LINGER PASS SUNSET. CONVECTION TO REFIRE OVERNIGHT OFFSHORE AS
THE UPPER TROUGH AXIS NEARS THE COAST AND NOCTURNAL DESTABILIZATION
OCCURS. SOME SHOWERS TO WORK THEIR WAY INLAND ACROSS THE LOWER
VALLEY AS THE SURFACE TROUGH NEARS THE COAST.
SUNDAY...ANOTHER GOOD CHANCE OF SHOWERS AND THUNDERSTORMS AS THE
UPPER TROUGH AXIS MOVES OVERHEAD. SOUTH TEXAS WILL BE ON THE
NORTHERN PERIPHERY OF THE TROUGH WITH BETTER CONVERGENCE AND
INSTABILITY SHIFTING FARTHER TO THE SOUTH WITH THE CENTER OF THE
TROUGH. IN ANY CASE...MOISTURE VALUES AND DEEP EASTERLY TO KEEP RAIN
CHANCES RATHER HIGH CONSIDERING THE LAST TWO WEEKS. FORECAST REMAINS
IN RANGE OF MAV/GFS GUIDANCE WITH MET/NAM LOOKING TO HIGH WITH A
MORE ROBUST SURFACE DEVELOPMENT WHICH DOES ON LOOK REASONABLE.
DAYTIME DESTABILIZATION TO TAKE PLACE BUT COULD BE LIMITED WITH
MULTI LAYERED CLOUD COVER LIMITED SURFACE HEATING. WITH THIS SAID
TEMPERATURES TO BE 7 TO 10 DEGREES COOLER THEN THE EXTREME HEAT THAT
WE HAVE EXPERIENCED.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...BY SUNDAY NIGHT THE
INVERTED TROUGH AXIS WILL BE TO THE WEST OF THE VALLEY. MOISTURE
WILL STILL BE SUBSTANTIAL...WITH PW VALUES BEGINNING THE PERIOD AT
2 INCHES...SLOWLY FALLING TO 1.6 BY TUESDAY MORNING. WITH THE
ABUNDANCE OF MOISTURE STILL PRESENT...STILL FEEL THAT SEABREEZE
SHOWERS WILL SPARK DURING THE AFTERNOON MONDAY...ALBEIT NOT AS
WIDESPREAD AS OVER THE WEEKEND. H5 RIDGE REBUILDS ACROSS TEXAS IN
THE WAKE OF THE TROUGH ON TUESDAY...WITH PW VALUES AOB 1.5 INCHES
THROUGH THE REST OF THE WEEK. THIS PRECLUDES THE CHANCE OF ANY
SEABREEZE ACTIVITY. TEMPERATURES WILL START TO RECOVER ON
MONDAY...JUMPING BACK INTO THE UPPER 90S AND LOW 100S. A GRADUAL
RETURN TO WIDESPREAD 100 DEGREE TEMPERATURES WILL CONTINUE THROUGH
THE REST OF THE WEEK.
MARINE...
NOW THROUGH SUNDAY...THE APPROACH OF THE UPPER TROUGH AND A
SURFACE TROUGH TO KEEP AN EAST WIND AT LIGHT TO MODERATE LEVELS
TODAY THROUGH SUNDAY. SHOWERS AND THUNDERSTORMS TO INCREASE IN
COVERAGE AND INTENSITY THROUGH THE PERIOD PRODUCING A SLIGHTLY
HIGHER SEA TONIGHT AND SUNDAY. NO SMALL CRAFT ADVISORIES ARE
ANTICIPATED.
MONDAY NIGHT THROUGH THURSDAY...WEAK GRADIENT WILL BE THE RULE
ACROSS THE MARINE ZONES THROUGH THE WEEK...WITH ONSHORE FLOW OF 10
TO 15 KNOTS EXPECTED EACH DAY. SEAS WILL GENERALLY RUN 2 TO 4
FEET...APPROACHING 5 FEET INITIALLY MONDAY NIGHT INTO TUESDAY. NO
ADVISORIES ARE EXPECTED.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV
68/59
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1027 AM CDT SAT AUG 10 2013
.UPDATE...
CLUSTERS OF SHOWERS WITH EMBEDDED STORMS PASSING ACROSS THE
SOUTHEASTERN CWA THIS MORNING...THE MAJORITY OF THIS MORNING`S
ACTIVITY OCCURRING SOUTH OF THE I-10 / EAST OF THE I-45 CORRIDORS.
GENERALLY...THE SOUTHERN THIRD OF THE FORECAST AREA WILL EXPERIENCE
PERIODIC SHOWERS AND THUNDER THROUGH MID-LATE AFTERNOON...LOCALLY
HEAVY RAIN ACCUMULATIONS OF BETWEEN A HALF AN INCH TO AN INCH.
A 2.2 TO 2.4 INCH PWAT MOISTURE RIDGE NOSING UP INTO THE NORTHWESTERN
GULF...WITH DECENT MID-UPPER CONVERGENCE ALONG THE WESTERN EDGE OF
THIS CENTRAL GULF CYCLONIC CIRCULATION...WILL KEEP MODERATE TO
HIGH PRECIPITATION CHANCES IN PLACE THROUGH THE WARMTH OF THE DAY.
RELATIVELY LOW CONVECTIVE TEMPERATURES IN THE MID TO UPPER 80S AND
LOCAL AREA SOUNDINGS DISPLAYING MU CAPES OF ABOVE 3K J/KG INDICATE
CONTINUED INLAND CONVECTIVE COVERAGE. EARLY SKC UP NORTH SHOULD
GIVE THOSE ACROSS THE NORTHERN CWA A HEAD START IN ACHIEVING UPPER
90F MAXIMUM TEMPERATURES...LOWER 90 MAX TEMPS ACROSS (NEAR) COASTAL
REGIONS THAT WILL BE UNDER OVERCAST SKIES/PERIODIC -TSRA FOR A GOOD
PART OF THE DAY. 31
&&
.PREV DISCUSSION... /ISSUED 622 AM CDT SAT AUG 10 2013/
AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE COASTAL WATERS HAVE
REACHED THE COAST AND ARE BEGINNING TO PUSH INLAND ACROSS
SOUTHEAST TEXAS. THIS ACTIVITY WILL AFFECT MOST SITES BEFORE
DISSIPATING LATE THIS AFTERNOON. EXPECT A SIMILAR SITUATION ON
SUNDAY AS ANOTHER WEAK DISTURBANCE MOVES ACROSS THE COASTAL
WATERS. 38
&&
PREV DISCUSSION... /ISSUED 420 AM CDT SAT AUG 10 2013/
DISCUSSION...
COASTAL RADARS SHOW SCATTERED SHOWERS AND THUNDERSTORMS IN THE
GULF WATERS THIS MORNING. AIRMASS ALONG THE COAST AND IN THE NW
GULF HAS BECOME VERY MOIST WITH GOES SOUNDER PRECIP WATER IMAGERY
SHOWING 2-2.2 INCHES WHERE CONVECTION IS ONGOING. WATER VAPOR
IMAGERY SHOWS UPPER LOW IN THE EAST CENTRAL GULF WHICH WILL
CONTINUE TO MOVE WEST ACROSS THE GULF AND DRIVE DEEPER MOISTURE
INLAND TODAY. UPPER LEVEL RIDGE HAS WEAKENED SOME BUT STRETCHES
ACROSS TEXAS THROUGH THE SE US. THINK SUBSIDENCE FROM THE RIDGE
MAY HOLD OFF CONVECTION INLAND FOR A LITTLE WHILE THIS MORNING BUT
DAY TIME HEATING WILL BE TOO MUCH FOR SCATTERED SHOWERS AND
THUNDERSTORMS NOT TO FORM. THE 06Z HRRR SHOWS CONVECTIVE
DEVELOPMENT ALONG THE COAST MAINLY 14-18Z AND THEN SCATTERED
ACTIVITY FURTHER INLAND FROM 18-21Z. THINK POPS OF 40 ALONG THE
COAST TRIMMING TO 20 FAR INLAND LOOKS ON TRACK. MIGHT BE ENOUGH
ACTIVITY TO BRING 50 POPS INLAND ALONG THE COAST BUT WILL HOLD OFF
TO SEE WHAT KIND OF COVERAGE DEVELOPS THROUGH THE MORNING.
CONVECTION FOR SUNDAY COULD BE ABOUT THE SAME COVERAGE AS TODAY
BUT PERHAPS A LITTLE LESS. MOISTURE WILL NOT BE AS HIGH WITH
PRECIP WATER AROUND 1.9-2 INCHES INSTEAD OF 2.2 INCHES.
NAM/GFS/ECMWF ARE ALL IN PRETTY GOOD AGREEMENT WITH THE CENTER OF
THE UPPER LOW TRACKING TOWARDS THE RIO GRANDE VALLEY ON SUNDAY.
VORTICITY WITH THE SYSTEM ALSO WEAKENS AND SHEARS OUT AS IT MOVES
INLAND. STILL THINK 30/40 POPS LOOK ON TRACK WITH 20 POPS FOR MORE
INLAND AREAS. BUT IF NAM IS MORE RIGHT...COULD HAVE MORE ACTIVITY
ON SUNDAY THAN TODAY. THINK THE NAM IS OVERDOING THE CONVECTION ON
SUNDAY AS UPPER LEVEL SUPPORT WILL NOT BE AS FAVORABLE.
THINK RAIN CHANCES WILL BE LESS ON MONDAY WITH 20 POPS IN PLACE.
THERE IS STILL DECENT MOISTURE WITH PRECIP WATER OF 1.9 INCHES BUT
THE RIDGE MAY BEGIN TO RE-ESTABLISH ITSELF OVER TX AT THIS TIME.
AGAIN LOOKS LIKE DAY TIME HEATING WILL BE THE MAIN TRIGGER FOR
CONVECTION BUT MOST LIKELY TIME WILL BE DURING THE AFTERNOON.
THE MAIN HAZARDS THE NEXT COUPLE OF DAYS WILL BE BRIEF HEAVY
RAINFALL AND LIGHTNING. COULD SEE SOME GUSTY WINDS BUT OVERALL NOT
A SEVERE THREAT. RAINFALL AMOUNTS THROUGH THE WEEKEND WILL LIKELY
BE AROUND A QUARTER TO HALF INCH WITH ISOLATED 1 INCH AMOUNTS IN
STRONGER STORMS. RAINFALL WILL PROVIDE SOME AREAS WITH A LITTLE
BREAK IN THE DROUGHT BUT NO REAL RELIEF. THEN AGAIN THERE COULD BE
SOME AREAS THAT DO NOT PICK UP ANY RAINFALL FROM THIS ENVIRONMENT.
NONETHELESS THE CLOUD COVER SHOULD HELP KEEP TEMPS LOWER AND AS A
RESULT WILL NOT NEED A HEAT ADVISORY FOR TODAY. WE WILL BE BACK TO
NEEDING 2 CONSECUTIVE DAYS OF A 108F HEAT INDEX TO ISSUE AN
ADVISORY.
THERE DOES LOOK TO BE A PATTERN CHANGE FOR THE EXTENDED FORECAST.
UPPER LEVEL RIDGE SHOULD BUILD OVER TX TUE/WED BUT THEN BECOMES
MORE ESTABLISHED OVER THE S ROCKIES BY THUR. TROUGHING OVER THE
GREAT LAKES WILL STRETCH TOWARDS THE MISS RIVER VALLEY SO NW FLOW
ALOFT MAY SUPPORT A FRONT PUSHING INTO THE AREA. GFS/ECMWF ARE
SHOWING A STRONGER FRONT MOVING INTO THE AREA THUR/FRI NEXT WEEK
SO WILL KEEP SOME RAIN CHANCES IN THE FORECAST ASSOCIATED WITH THE
FRONT. DRIER AIR MAY KNOCK MIN/MAX TEMPS DOWN A COUPLE OF DEGREES.
MODELS AGREE WITH AMPLIFYING THE PATTERN NEXT WEEKEND SO THIS
PATTERN MAY PERSIST A BIT LONGER AND GIVE SE TX A DECENT BREAK
FROM THE HEAT. 39
&&
MARINE...
SCATTERED SHOWERS ONGOING ACROSS THE COASTAL WATERS THIS MORNING
AS A WEAK EASTERLY WAVE APPROACHES THE REGION. THIS FEATURE AND
ANOTHER DISTURBANCE EXPECTED ON SUNDAY WILL KEEP SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE MARINE ZONES THROUGH THE WEEKEND. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 99 78 98 75 97 / 20 20 20 20 20
HOUSTON (IAH) 93 78 95 77 95 / 40 20 40 20 20
GALVESTON (GLS) 88 83 90 81 91 / 60 30 40 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...31
AREA FORECAST DISCUSSION...UPDATED
NWS BROWNSVILLE TX
933 AM CDT SAT AUG 10 2013
.DISCUSSION...MORNING SOUNDING AND SATELLITE DERIVED PRECIPITABLE
WATER ESTIMATES CONTINUE TO INDICATE A VERY SATURATED
AIRMASS...ASSOCIATED WITH A TROPICAL WAVE MOVING WESTWARD ACROSS
THE WEST CENTRAL GULF HAS MOVED INTO THE AREA. RAP AND MODIFIED
MORNING FORECAST SOUNDINGS INDICATE WE ARE APPROACHING CONVECTIVE
TEMPERATURE WITH LITTLE LOWER TROPOSPHERIC WARMING EXPECTED DUE TO
THE SATURATED AIRMASS AND CU STREAKS AND CONVERGENCE ZONES ARE
BECOMING READILY APPARENT ON VISIBLE SATELLITE IMAGERY. THE TWO
STRONGEST ZONES ARE ASSOCIATED WITH THE SEABREEZE IN EASTERN
CAMERON AND WILLACY COUNTY...AND DEVELOPING SHOWER ACTIVITY NEAR
WESLACO. A GENERALLY DIFFLUENT UPPER LEVEL PATTERN JUST OFFSHORE
IS PRODUCING WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS OVER OUR
COASTAL WATERS FOCUSED ALONG WEAK SURFACE TROUGHING MOVING SLOWLY
WESTWARD UNDER THIS FEATURE.
ALL THAT BEING SAID EXPECTING CONVECTIVE DEVELOPMENT TO INCREASE
MARKEDLY OVER THE NEXT TWO TO THREE HOURS WITH SCATTERED TO
NUMEROUS SHOWERS AND STORMS DEVELOPING...POSSIBLY BECOMING
WIDESPREAD IF THE MORE FAVORABLE UPPER LEVEL ENVIRONMENT OVER THE
GULF MOVES ONSHORE. HOWEVER NEAR AND SHORT TERM GUIDANCE HAS BEEN
CONSISTENTLY SHOWING WEAKENING OF THIS FEATURE AS IT MOVES INLAND.
NEVERTHELESS THE CURRENT THERMODYNAMIC AND MOISTURE PROFILE WILL
PROVIDE SHRA/TSRA. THE SHOWERS SHOULD GREATLY OUTNUMBER THE STORMS
BUT THERE WILL PROBABLY BE A FEW RUMBLES OF THUNDER.
THE STRONGEST CELLS WILL PRODUCE EXCEPTIONALLY EFFICIENT RAINFALL
RATES...ON THE ORDER OF TWO TO THREE INCHES PER HOUR AS THEY MOVE
WEST AT AROUND 15 MPH. MOST CONVECTION WILL PROBABLY BE LESS
INTENSE HOWEVER...AND PRODUCE RAINFALL RATES CLOSER TO ONE HALF TO
TWO INCHES PER HOUR. TOTAL ACCUMULATIONS AT ANY ONE LOCATION WILL
LIKELY BE LESS AS THE ACTIVITY MOVES SLOWLY WESTWARD. THE GRIDDED
FORECASTS SHOW THE ANTICIPATED EVOLUTION WELL AND NO SIGNIFICANT
CHANGES ARE PLANNED FOR NOW. /68-JGG/
&&
.PREV DISCUSSION... /ISSUED 634 AM CDT SAT AUG 10 2013/
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.
AVIATION...EXPECTING CONVECTION TO DEVELOP LATER THIS MORNING
FIRST ALONG THE COAST AND THEN MOVE INLAND THIS AFTERNOON.
EXPECTING BEST CHANCES AND COVERAGE BETWEEN 16-21Z IN THE EAST
AND 18-23Z IN THE CENTRAL AND WEST. VFR CONDITIONS TO PREVAIL
OUTSIDE OF THE CONVECTION WITH TEMPORARY MVFR CIGS VSBY IN AND
NEAR THE SCATTERED THUNDERSTORMS AND SHOWERS. MOISTURE VALUES TO
REMAIN RATHER HIGH SO EXPECT A LAYER OF STRATUS TO DEVELOP
OVERNIGHT AOA MVFR. SURFACE WIND TO REMAIN LIGHT FROM A GENERAL
EAST DIRECTION.
PREV DISCUSSION... /ISSUED 403 AM CDT SAT AUG 10 2013/
SHORT TERM /NOW THROUGH SUNDAY/...SATELLITE AND RADAR LOOPS
INDICATE MOISTURE IS BEGINNING TO MOVE INTO COASTAL WATERS.
SHOWERS AND AN ISOLATED THUNDERSTORM OR TWO HAVE BEEN MOVING INTO
NORTHEAST MEXICO SINCE 1AM IN ADVANCE OF THE LARGE SCALE MID TO
UPPER LEVEL TROUGH CENTERED JUST NORTH OF THE YUCATAN.
FOR TODAY...LOOKING AT SHOWERS THIS MORNING TO FAVOR THE IMMEDIATE
COASTAL AREAS AND THE GULF WATERS. NOT UNTIL THE MOISTURE COLUMN
BECOMES NEARLY SATURATED AROUND OR AFTER 18Z AND PWATS EXCEED 2.25
INCHES WILL WE SEE CONVECTION DEVELOP FARTHER INLAND. A DEEPENING
EASTERLY FLOW TO ENHANCE SURFACE CONVERGENCE ALONG THE SEABREEZE AND
DESTABILIZATION OF THE ATMOSPHERE AS SURFACE HEATING GETS GOING THIS
MORNING BEFORE THE CLOUDS INCREASE TO GIVE THE LOWER AND MID VALLEY
THE BEST AND HIGHEST CHANCE OF RAIN IN LONG WHILE. INHERITED
FORECAST LOOKS GOOD AND REMAINS IN LINE WITH LATEST GUIDANCE. DID
NOT MENTION HEAVY RAIN IN THE FORECAST WITH THE ANTICIPATION OF
CELLS TO MOVE STEADILY EAST TO WEST UNDER A 15 TO 20 KNOT MID LAYER
FLOW. SURFACE TROUGHING LOOKS TO REMAIN JUST OFFSHORE ALONG WITH
UPPER DIVERGENCE KEEPING CONVECTION INITIATION EAST OF THE COAST
WITH THE HEAVIEST AND MOST CONCENTRATED AREA OF RAIN OFFSHORE.
WITH THIS SAID POCKETS OF HEAVY RAIN ARE STILL POSSIBLE INLAND...AS
MOISTURE INCREASES...AND ANY WESTWARD SHIFT OF THE TROUGH COULD PUSH
THE HEAVIER RAIN INLAND. TEMPERATURES TO CLIMB QUICKLY WITH SUNNY
CONDITIONS EARLY ON ESPECIALLY OUT WEST. THEN THEY ARE LIKELY TO
FALL AS RAIN DEVELOPS.
TONIGHT...UPPER TROUGH CONTINUES TO TRACK WESTWARD. CONVECTION TO
WANE INLAND AS STABILIZATION OCCURS WITH WESTERN AREAS SEEING SOME
RAIN LINGER PASS SUNSET. CONVECTION TO REFIRE OVERNIGHT OFFSHORE AS
THE UPPER TROUGH AXIS NEARS THE COAST AND NOCTURNAL DESTABILIZATION
OCCURS. SOME SHOWERS TO WORK THEIR WAY INLAND ACROSS THE LOWER
VALLEY AS THE SURFACE TROUGH NEARS THE COAST.
SUNDAY...ANOTHER GOOD CHANCE OF SHOWERS AND THUNDERSTORMS AS THE
UPPER TROUGH AXIS MOVES OVERHEAD. SOUTH TEXAS WILL BE ON THE
NORTHERN PERIPHERY OF THE TROUGH WITH BETTER CONVERGENCE AND
INSTABILITY SHIFTING FARTHER TO THE SOUTH WITH THE CENTER OF THE
TROUGH. IN ANY CASE...MOISTURE VALUES AND DEEP EASTERLY TO KEEP RAIN
CHANCES RATHER HIGH CONSIDERING THE LAST TWO WEEKS. FORECAST REMAINS
IN RANGE OF MAV/GFS GUIDANCE WITH MET/NAM LOOKING TO HIGH WITH A
MORE ROBUST SURFACE DEVELOPMENT WHICH DOES ON LOOK REASONABLE.
DAYTIME DESTABILIZATION TO TAKE PLACE BUT COULD BE LIMITED WITH
MULTI LAYERED CLOUD COVER LIMITED SURFACE HEATING. WITH THIS SAID
TEMPERATURES TO BE 7 TO 10 DEGREES COOLER THEN THE EXTREME HEAT THAT
WE HAVE EXPERIENCED.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...BY SUNDAY NIGHT THE
INVERTED TROUGH AXIS WILL BE TO THE WEST OF THE VALLEY. MOISTURE
WILL STILL BE SUBSTANTIAL...WITH PW VALUES BEGINNING THE PERIOD AT
2 INCHES...SLOWLY FALLING TO 1.6 BY TUESDAY MORNING. WITH THE
ABUNDANCE OF MOISTURE STILL PRESENT...STILL FEEL THAT SEABREEZE
SHOWERS WILL SPARK DURING THE AFTERNOON MONDAY...ALBEIT NOT AS
WIDESPREAD AS OVER THE WEEKEND. H5 RIDGE REBUILDS ACROSS TEXAS IN
THE WAKE OF THE TROUGH ON TUESDAY...WITH PW VALUES AOB 1.5 INCHES
THROUGH THE REST OF THE WEEK. THIS PRECLUDES THE CHANCE OF ANY
SEABREEZE ACTIVITY. TEMPERATURES WILL START TO RECOVER ON
MONDAY...JUMPING BACK INTO THE UPPER 90S AND LOW 100S. A GRADUAL
RETURN TO WIDESPREAD 100 DEGREE TEMPERATURES WILL CONTINUE THROUGH
THE REST OF THE WEEK.
MARINE...
NOW THROUGH SUNDAY...THE APPROACH OF THE UPPER TROUGH AND A
SURFACE TROUGH TO KEEP AN EAST WIND AT LIGHT TO MODERATE LEVELS
TODAY THROUGH SUNDAY. SHOWERS AND THUNDERSTORMS TO INCREASE IN
COVERAGE AND INTENSITY THROUGH THE PERIOD PRODUCING A SLIGHTLY
HIGHER SEA TONIGHT AND SUNDAY. NO SMALL CRAFT ADVISORIES ARE
ANTICIPATED.
MONDAY NIGHT THROUGH THURSDAY...WEAK GRADIENT WILL BE THE RULE
ACROSS THE MARINE ZONES THROUGH THE WEEK...WITH ONSHORE FLOW OF 10
TO 15 KNOTS EXPECTED EACH DAY. SEAS WILL GENERALLY RUN 2 TO 4
FEET...APPROACHING 5 FEET INITIALLY MONDAY NIGHT INTO TUESDAY. NO
ADVISORIES ARE EXPECTED.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT:
HTTP://WEATHER.GOV/RGV
68/67
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
622 AM CDT SAT AUG 10 2013
.DISCUSSION...
SEE AVIATION FOR 12Z TAF DISCUSSION
&&
.AVIATION...
SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE COASTAL WATERS HAVE
REACHED THE COAST AND ARE BEGINNING TO PUSH INLAND ACROSS
SOUTHEAST TEXAS. THIS ACTIVITY WILL AFFECT MOST SITES BEFORE
DISSIPATING LATE THIS AFTERNOON. EXPECT A SIMILAR SITUATION ON
SUNDAY AS ANOTHER WEAK DISTURBANCE MOVES ACROSS THE COASTAL
WATERS. 38
&&
.PREV DISCUSSION... /ISSUED 420 AM CDT SAT AUG 10 2013/
DISCUSSION...
COASTAL RADARS SHOW SCATTERED SHOWERS AND THUNDERSTORMS IN THE
GULF WATERS THIS MORNING. AIRMASS ALONG THE COAST AND IN THE NW
GULF HAS BECOME VERY MOIST WITH GOES SOUNDER PRECIP WATER IMAGERY
SHOWING 2-2.2 INCHES WHERE CONVECTION IS ONGOING. WATER VAPOR
IMAGERY SHOWS UPPER LOW IN THE EAST CENTRAL GULF WHICH WILL
CONTINUE TO MOVE WEST ACROSS THE GULF AND DRIVE DEEPER MOISTURE
INLAND TODAY. UPPER LEVEL RIDGE HAS WEAKENED SOME BUT STRETCHES
ACROSS TEXAS THROUGH THE SE US. THINK SUBSIDENCE FROM THE RIDGE
MAY HOLD OFF CONVECTION INLAND FOR A LITTLE WHILE THIS MORNING BUT
DAY TIME HEATING WILL BE TOO MUCH FOR SCATTERED SHOWERS AND
THUNDERSTORMS NOT TO FORM. THE 06Z HRRR SHOWS CONVECTIVE
DEVELOPMENT ALONG THE COAST MAINLY 14-18Z AND THEN SCATTERED
ACTIVITY FURTHER INLAND FROM 18-21Z. THINK POPS OF 40 ALONG THE
COAST TRIMMING TO 20 FAR INLAND LOOKS ON TRACK. MIGHT BE ENOUGH
ACTIVITY TO BRING 50 POPS INLAND ALONG THE COAST BUT WILL HOLD OFF
TO SEE WHAT KIND OF COVERAGE DEVELOPS THROUGH THE MORNING.
CONVECTION FOR SUNDAY COULD BE ABOUT THE SAME COVERAGE AS TODAY
BUT PERHAPS A LITTLE LESS. MOISTURE WILL NOT BE AS HIGH WITH
PRECIP WATER AROUND 1.9-2 INCHES INSTEAD OF 2.2 INCHES.
NAM/GFS/ECMWF ARE ALL IN PRETTY GOOD AGREEMENT WITH THE CENTER OF
THE UPPER LOW TRACKING TOWARDS THE RIO GRANDE VALLEY ON SUNDAY.
VORTICITY WITH THE SYSTEM ALSO WEAKENS AND SHEARS OUT AS IT MOVES
INLAND. STILL THINK 30/40 POPS LOOK ON TRACK WITH 20 POPS FOR MORE
INLAND AREAS. BUT IF NAM IS MORE RIGHT...COULD HAVE MORE ACTIVITY
ON SUNDAY THAN TODAY. THINK THE NAM IS OVERDOING THE CONVECTION ON
SUNDAY AS UPPER LEVEL SUPPORT WILL NOT BE AS FAVORABLE.
THINK RAIN CHANCES WILL BE LESS ON MONDAY WITH 20 POPS IN PLACE.
THERE IS STILL DECENT MOISTURE WITH PRECIP WATER OF 1.9 INCHES BUT
THE RIDGE MAY BEGIN TO RE-ESTABLISH ITSELF OVER TX AT THIS TIME.
AGAIN LOOKS LIKE DAY TIME HEATING WILL BE THE MAIN TRIGGER FOR
CONVECTION BUT MOST LIKELY TIME WILL BE DURING THE AFTERNOON.
THE MAIN HAZARDS THE NEXT COUPLE OF DAYS WILL BE BRIEF HEAVY
RAINFALL AND LIGHTNING. COULD SEE SOME GUSTY WINDS BUT OVERALL NOT
A SEVERE THREAT. RAINFALL AMOUNTS THROUGH THE WEEKEND WILL LIKELY
BE AROUND A QUARTER TO HALF INCH WITH ISOLATED 1 INCH AMOUNTS IN
STRONGER STORMS. RAINFALL WILL PROVIDE SOME AREAS WITH A LITTLE
BREAK IN THE DROUGHT BUT NO REAL RELIEF. THEN AGAIN THERE COULD BE
SOME AREAS THAT DO NOT PICK UP ANY RAINFALL FROM THIS ENVIRONMENT.
NONETHELESS THE CLOUD COVER SHOULD HELP KEEP TEMPS LOWER AND AS A
RESULT WILL NOT NEED A HEAT ADVISORY FOR TODAY. WE WILL BE BACK TO
NEEDING 2 CONSECUTIVE DAYS OF A 108F HEAT INDEX TO ISSUE AN
ADVISORY.
THERE DOES LOOK TO BE A PATTERN CHANGE FOR THE EXTENDED FORECAST.
UPPER LEVEL RIDGE SHOULD BUILD OVER TX TUE/WED BUT THEN BECOMES
MORE ESTABLISHED OVER THE S ROCKIES BY THUR. TROUGHING OVER THE
GREAT LAKES WILL STRETCH TOWARDS THE MISS RIVER VALLEY SO NW FLOW
ALOFT MAY SUPPORT A FRONT PUSHING INTO THE AREA. GFS/ECMWF ARE
SHOWING A STRONGER FRONT MOVING INTO THE AREA THUR/FRI NEXT WEEK
SO WILL KEEP SOME RAIN CHANCES IN THE FORECAST ASSOCIATED WITH THE
FRONT. DRIER AIR MAY KNOCK MIN/MAX TEMPS DOWN A COUPLE OF DEGREES.
MODELS AGREE WITH AMPLIFYING THE PATTERN NEXT WEEKEND SO THIS
PATTERN MAY PERSIST A BIT LONGER AND GIVE SE TX A DECENT BREAK
FROM THE HEAT.
39
MARINE...
SCATTERED SHOWERS ONGOING ACROSS THE COASTAL WATERS THIS MORNING
AS A WEAK EASTERLY WAVE APPROACHES THE REGION. THIS FEATURE AND
ANOTHER DISTURBANCE EXPECTED ON SUNDAY WILL KEEP SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE MARINE ZONES THROUGH THE WEEKEND. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 99 78 97 75 97 / 20 20 20 20 20
HOUSTON (IAH) 95 78 95 77 95 / 40 20 40 20 20
GALVESTON (GLS) 90 82 90 81 91 / 40 20 40 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
420 AM CDT SAT AUG 10 2013
.DISCUSSION...
COASTAL RADARS SHOW SCATTERED SHOWERS AND THUNDERSTORMS IN THE
GULF WATERS THIS MORNING. AIRMASS ALONG THE COAST AND IN THE NW
GULF HAS BECOME VERY MOIST WITH GOES SOUNDER PRECIP WATER IMAGERY
SHOWING 2-2.2 INCHES WHERE CONVECTION IS ONGOING. WATER VAPOR
IMAGERY SHOWS UPPER LOW IN THE EAST CENTRAL GULF WHICH WILL
CONTINUE TO MOVE WEST ACROSS THE GULF AND DRIVE DEEPER MOISTURE
INLAND TODAY. UPPER LEVEL RIDGE HAS WEAKENED SOME BUT STRETCHES
ACROSS TEXAS THROUGH THE SE US. THINK SUBSIDENCE FROM THE RIDGE
MAY HOLD OFF CONVECTION INLAND FOR A LITTLE WHILE THIS MORNING BUT
DAY TIME HEATING WILL BE TOO MUCH FOR SCATTERED SHOWERS AND
THUNDERSTORMS NOT TO FORM. THE 06Z HRRR SHOWS CONVECTIVE
DEVELOPMENT ALONG THE COAST MAINLY 14-18Z AND THEN SCATTERED
ACTIVITY FURTHER INLAND FROM 18-21Z. THINK POPS OF 40 ALONG THE
COAST TRIMMING TO 20 FAR INLAND LOOKS ON TRACK. MIGHT BE ENOUGH
ACTIVITY TO BRING 50 POPS INLAND ALONG THE COAST BUT WILL HOLD OFF
TO SEE WHAT KIND OF COVERAGE DEVELOPS THROUGH THE MORNING.
CONVECTION FOR SUNDAY COULD BE ABOUT THE SAME COVERAGE AS TODAY
BUT PERHAPS A LITTLE LESS. MOISTURE WILL NOT BE AS HIGH WITH
PRECIP WATER AROUND 1.9-2 INCHES INSTEAD OF 2.2 INCHES.
NAM/GFS/ECMWF ARE ALL IN PRETTY GOOD AGREEMENT WITH THE CENTER OF
THE UPPER LOW TRACKING TOWARDS THE RIO GRANDE VALLEY ON SUNDAY.
VORTICITY WITH THE SYSTEM ALSO WEAKENS AND SHEARS OUT AS IT MOVES
INLAND. STILL THINK 30/40 POPS LOOK ON TRACK WITH 20 POPS FOR MORE
INLAND AREAS. BUT IF NAM IS MORE RIGHT...COULD HAVE MORE ACTIVITY
ON SUNDAY THAN TODAY. THINK THE NAM IS OVERDOING THE CONVECTION ON
SUNDAY AS UPPER LEVEL SUPPORT WILL NOT BE AS FAVORABLE.
THINK RAIN CHANCES WILL BE LESS ON MONDAY WITH 20 POPS IN PLACE.
THERE IS STILL DECENT MOISTURE WITH PRECIP WATER OF 1.9 INCHES BUT
THE RIDGE MAY BEGIN TO RE-ESTABLISH ITSELF OVER TX AT THIS TIME.
AGAIN LOOKS LIKE DAY TIME HEATING WILL BE THE MAIN TRIGGER FOR
CONVECTION BUT MOST LIKELY TIME WILL BE DURING THE AFTERNOON.
THE MAIN HAZARDS THE NEXT COUPLE OF DAYS WILL BE BRIEF HEAVY
RAINFALL AND LIGHTNING. COULD SEE SOME GUSTY WINDS BUT OVERALL NOT
A SEVERE THREAT. RAINFALL AMOUNTS THROUGH THE WEEKEND WILL LIKELY
BE AROUND A QUARTER TO HALF INCH WITH ISOLATED 1 INCH AMOUNTS IN
STRONGER STORMS. RAINFALL WILL PROVIDE SOME AREAS WITH A LITTLE
BREAK IN THE DROUGHT BUT NO REAL RELIEF. THEN AGAIN THERE COULD BE
SOME AREAS THAT DO NOT PICK UP ANY RAINFALL FROM THIS ENVIRONMENT.
NONETHELESS THE CLOUD COVER SHOULD HELP KEEP TEMPS LOWER AND AS A
RESULT WILL NOT NEED A HEAT ADVISORY FOR TODAY. WE WILL BE BACK TO
NEEDING 2 CONSECUTIVE DAYS OF A 108F HEAT INDEX TO ISSUE AN
ADVISORY.
THERE DOES LOOK TO BE A PATTERN CHANGE FOR THE EXTENDED FORECAST.
UPPER LEVEL RIDGE SHOULD BUILD OVER TX TUE/WED BUT THEN BECOMES
MORE ESTABLISHED OVER THE S ROCKIES BY THUR. TROUGHING OVER THE
GREAT LAKES WILL STRETCH TOWARDS THE MISS RIVER VALLEY SO NW FLOW
ALOFT MAY SUPPORT A FRONT PUSHING INTO THE AREA. GFS/ECMWF ARE
SHOWING A STRONGER FRONT MOVING INTO THE AREA THUR/FRI NEXT WEEK
SO WILL KEEP SOME RAIN CHANCES IN THE FORECAST ASSOCIATED WITH THE
FRONT. DRIER AIR MAY KNOCK MIN/MAX TEMPS DOWN A COUPLE OF DEGREES.
MODELS AGREE WITH AMPLIFYING THE PATTERN NEXT WEEKEND SO THIS
PATTERN MAY PERSIST A BIT LONGER AND GIVE SE TX A DECENT BREAK
FROM THE HEAT.
39
&&
.MARINE...
SCATTERED SHOWERS ONGOING ACROSS THE COASTAL WATERS THIS MORNING
AS A WEAK EASTERLY WAVE APPROACHES THE REGION. THIS FEATURE AND
ANOTHER DISTURBANCE EXPECTED ON SUNDAY WILL KEEP SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE MARINE ZONES THROUGH THE WEEKEND. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 99 78 97 75 97 / 20 20 20 20 20
HOUSTON (IAH) 95 78 95 77 95 / 40 20 40 20 20
GALVESTON (GLS) 90 82 90 81 91 / 40 20 40 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1126 PM CDT FRI AUG 9 2013
.DISCUSSION...
/See Aviation Discussion below/
&&
.AVIATION...
Showers and thunderstorms at all airport locations in the forecast
area have dissipated due to nighttime ground cooling. Mostly VFR
flying conditions will prevail the next 24 hours across the forecast
area.
A weak cold front currently along a line from near Brady to Sonora
is slowing down as it tries to push through the forecast area. Winds
north of the front have become northerly or northeasterly at 5 to
10kt.
The GFS model forecasts the front to continue to move south past the
forecast area by tomorrow morning and then stalls the front and then
lifts the front north back into the forecast area by Saturday night,
developing a few showers along the front. Similarly the NAM model
lingers the front across southern counties...and in association with
afternoon heating...flares up scattered showers and thunderstorms
along the stalled front in the vicinity of Junction...Sonora and
Brady airports. Current TAFS reflect a combination of both models
because the front has slowed its southeastward motion based on
satellite and radar imagery with a position expected to be between
both model forecasts.
.PREV DISCUSSION... /ISSUED 620 PM CDT FRI AUG 9 2013/
.DISCUSSION...
/See Aviation Discussion below/
&&
.AVIATION...
Primary aviation concerns the next 3 to 4 hours are local areas of
showers and isolated thunderstorms that may product gusty
surface winds to 45kt...brief heavy rain and hazardous lightning.
Currently some showers and thunderstorms...with measured
lightning...are noted in Shackelford...Jones...Coke and Sterling
counties.
Showers are associated with a very weak frontal boundary stretching
from east-northeast to west-southwest through Jones and Sterling
Counties. Satellite imagery...radar imagery and models concur...the
front will move slowly toward the south-southeast the next 24 hours
weakening as it goes...then nearly dissipate southeast of Junction
and Kimble County on Saturday. Winds across Junction... Sonora...
San Angelo and Brady will shift from light southerly ahead of the
front to light northerly as the front passes to the southeast.
.PREV DISCUSSION... /ISSUED 307 PM CDT FRI AUG 9 2013/
.SHORT TERM...
.Tonight and Saturday...
Isolated severe thunderstorms with damaging winds possible again
this afternoon and evening. The best potential will be in the Big
Country, along a weak cold front along the I-20 corridor.
Discussion:
Conditions are similar to yesterday with an inverted V sounding.
Instability was fairly high. RAP ML CAPES ranged from 2000-3000 J/KG
in the Big Country and Concho Valley, with the highest values near
Sweetwater. Focus for initial storm development will be a weak front
along the I-20 corridor...although a few storms will likely develop
farther south along thunderstorm outflow boundaries. Main
thunderstorm threat will be damaging winds. With weak steering
currents, storm movement will be slow. This may also bring
localized flooding in urban areas.
The front is expected to move south Saturday afternoon...becoming
stationary somewhere along the I-10 corridor...although placement is
uncertain. The main threat will be strong gusty winds and dangerous
lightning.
.LONG TERM...
.Saturday Night...
Slight chance of storms will linger into the evening hours.
Whatever is left of the weak cold front will remain somewhere across
West Central Texas, along with whatever outflow boundaries may still
be in the area. Any storms that develop during the heat of the day
will keep going until shortly after sunset before dissipating.
.Sunday into Wednesday...
A dry pattern will prevail, with temperatures not quite as hot.
Upper level ridge of high pressure takes a bigger role for early
next week, slowly shifting back to the west. Low level temperatures
and 850 mb readings are FORECASTED to be cooler by a few degrees, so
forecast highs at or hopefully just below the 100 degree mark. With
the ridge in place overhead and without a boundary to aid, getting
any thunderstorms to develop will be extremely tough. Will opt to
keep the forecast dry.
.Wednesday Night into Friday...
Storms will be possible again across the Big Country.
By late Wednesday, the upper level ridge will have shifted far
enough to the west to put West Central Texas into northwest flow.
This is typically a wetter pattern, as storms develop across the
Panhandle during the afternoon and move southeast into the area
during the overnight hours. Best chances look to be across the Big
Country and Heartland with the chances decreasing to the southwest.
Have inserted pops for the northeast portions of the area for now,
and leave the remainder of the area dry. But if the northwest flow
sets up as the models suggest, may have to expand the rainfall
coverage as we get into next week.
Otherwise, northwest flow is usually a little cooler as well. This
is shown in the model guidance, showing highs near climatology
normals in the mid to upper 90s.
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 71 96 76 96 75 / 20 20 20 10 10
SAN ANGELO 71 99 74 97 74 / 20 20 20 10 10
JUNCTION 72 100 75 97 75 / 10 20 20 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
LYONS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
754 AM EDT SAT AUG 10 2013
.SYNOPSIS...
UNSETTLED PATTERN TO CONTINUE THROUGH THE WEEKEND AS FRONT STAYS
SITUATED ACROSS THE MID ATLANTIC INTO THE MID MISSISSIPPI VALLEY.
THE FRONT WEAKENS MONDAY WITH ANOTHER FRONT SHIFTING ACROSS OUR
REGION TUESDAY. HIGH PRESSURE WILL BUILD ACROSS TO OUR NORTH MID
TO LATE NEXT WEEK BUT ENOUGH MOISTURE SITUATED ACROSS THE
SOUTHEAST WILL KEEP THE THREAT OF SHOWERS AND STORMS AROUND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM EDT SATURDAY...
UPPER TROUGH ACROSS THE GREAT LAKES AND MID MS VALLEY EXPECTED TO
TRACK EAST WITH MID LEVEL SHORTWAVES MOVING ACROSS WHILE A FRONT
SLOWLY SAGS SOUTHWARD INTO OUR AREA BY SUNDAY. FOR THIS MORNING WE
ARE SEEING SOME HEAVY RAIN SHOWERS/EMBEDDED THUNDER ACROSS THE FAR
SW VA CORRIDOR INTO PORTIONS OF NW NC. THIS IN ASSOCIATION WITH SFC
THETA-E CONVERGENCE ALONG WITH PREFRONTAL TROUGH. THE LATEST RAP/RUC
SHOWING THAT ACTIVITY SWINGS EAST THROUGH DAWN INTO THE PIEDMONT
ALTHOUGH SOME WEAKENING IN THE NEW RIVER VALLEY APPEARS TO LIMIT
WHAT THE RAP SHOWS. FURTHER UPSTREAM CONVECTION ACROSS KY/WV SHOULD
SETTLE TOWARD THE SOUTHEAST WV AREA BY DAWN AS WELL.
THE FORECAST AND MODELS THE LAST FEW DAYS ADVERTISED HIGH POPS WHICH
HAS NOT WORKED OUT AT TIMES BUT WITH IMPROVING LOW LVL CONVERGENCE
AND PROXIMITY OF UPPER SHORTWAVE AM HESITANT TO KEEP POPS LOW
TODAY. I LEANED TOWARD THE RAP THIS MORNING BUT TRANSITIONED
TOWARD THE GFS THIS AFTERNOON BLENDED WITH THE PREVIOUS FORECAST.
AM THINKING THE CORRIDOR ALONG I-64 EAST INTO THE SHENANDOAH
VALLEY WILL BE ACTIVE LATE THIS MORNING INTO EARLY AFTERNOON WITH
DENSITY OF STORMS SHIFTING CONVECTION WITH OUTFLOW SOUTHEAST INTO
THE FOOTHILLS AND PIEDMONT THIS AFTERNOON. SO FOR NOW WILL HAVE
INCREASING POPS IN THE NORTH GOING TOWARD LIKELY BY MIDDAY THEN
SHIFTING HIGHER POPS SWD THRU THE AFTERNOON. NOT GOING TO PLAY
WITH 30 VS 50-60 POPS AS AIRMASS SOUPY ENOUGH AND PLENTY OF LIFT
WITH SOME UPPER SUPPORT THE HIGHER POPS AREA WIDE.
AGAIN...THINNING OUT OF CLOUDS SHOULD ALLOW SOME SUN TO HEAT
THINGS UP ALTHOUGH JUST GOING TO BE ENOUGH CLOUD COVER ALL DAY TO
PREVENT THE TEMPS FROM WARMING TOO HIGH UNLIKE WHAT HAPPENED
FRIDAY. WENT MORE TOWARD MET MOS EAST WHICH HAS NEAR 90 WHICH IS
BETWEEN THE COOLER ECMWF AND WARMER MAV. WITH CONVECTION AND
CLOUDS MORE PREVALENT OVER THE NORTHWEST WENT THE COOLER
MET...WITH UPPER 70S TO LOWER 80S.
THOUGH HEAVY RAIN THREAT REMAINS...THE ISOLATED FLASH FLOOD THREAT
REMAINS THAT A WATCH IS NOT NEEDED YET...BUT WILL HAVE TO SEE HOW
STORMS LINE UP THIS AFTERNOON TO SEE IF WE NEED ONE. THERE IS ALSO A
SMALL RISK OF SVR STORMS WITH THE SRN BELT OF WESTERLIES ALLOWING
FOR SOME WIND THREAT.
SHOULD SEE SOME COVERAGE ENTERING TONIGHT AS MODELS KEEP SHORTWAVE
ENERGY MOVING FROM WV/KY INTO NRN VA. MODELS ARE SHOWING MORE
AGREEMENT IN HAVING BEST CHANCE WEST AND AND NORTH...ALTHOUGH SOME
SHIFT IT SOUTH INTO THE NC/VA BORDER AREA AS WEAK LOW MOVES ACROSS.
AT THIS TIME HAVE LIKELY POPS IN THE EARLY EVENING TAPERING TO 40-50
BY MIDNIGHT...WITH NO FOCUSED AREA FOR HIGHER OR LOWER POPS...AS
LOSS OF HEATING EXPECTED TO RESULT IN MORE SCATTERED COVERAGE.
STILL MUGGY WITH DRIER AIR WELL NORTH ACROSS WRN PA/NY INTO THE
GREAT LAKES STATES. LOWS WILL RANGE FROM THE MID TO UPPER 60S ACROSS
THE WEST TO AROUND 70 AT ROANOKE AND POINTS EAST.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
AS OF 320 AM EDT SATURDAY...
THE AREA WILL CONTINUE WITHIN A PROGRESSIVE REGIME WITH DISTINCT
BOUTS OF HEAVY SHOWER AND THUNDERSTORM CHANCES. THE FIRST OF THESE
WILL BE DURING THE DAY SUNDAY WHEN A COLD FRONT PASSES THROUGH THE
REGION. MOST OF THE ACTIVITY WILL HEAD SOUTH OF THE AREA BY SUNDAY
EVENING. SURFACE HIGH PRESSURE BUILDS IN BEHIND THE FRONT BRIEFLY BY
MONDAY MORNING. HOWEVER...THE AXIS OF THIS HIGH/RIDGE WILL SHIFT
EAST OF THE AREA BY MONDAY MORNING...AND THUS ALLOW FOR SOUTHEAST
LOW LEVEL FLOW TO BRING LINGERING MOISTURE BACK INTO THE SOUTHWEST
PARTS OF THE FORECAST AREA. REGIONS ALONG THE CREST OF THE BLUE
RIDGE FROM ROUGHLY FLOYD VA SOUTHWEST INTO THE NORTHERN MOUNTAINS OF
NC WILL HAVE THE GREATEST POTENTIAL FOR SHOWERS AND A FEW
THUNDERSTORMS ON MONDAY.
BY MONDAY EVENING...THERE WILL BE A DECREASE IN COVERAGE OF THE
PRECIPITATION WILL THE LOSS OF DAYTIME HEATING. HOWEVER...OUR NEXT
APPROACHING COLD FRONT WILL START TO ALLOW FOR A RETURN OF ISOLATED
TO SCATTERED SHOWERS ACROSS THE FAR WESTERN PARTS OF THE REGION BY
SUNRISE TUESDAY. DURING THE DAY TUESDAY THIS FRONT WILL CROSS THE
AREA WITH A GOOD COVERAGE OF SHOWERS AND STORMS. SHOWERS ARE LIKELY
WITH SCATTERED THUNDERSTORMS ALONG AND EAST OF THE CREST OF THE BLUE
RIDGE BY TUESDAY AFTERNOON. TUESDAY NIGHT THERE WILL BE A GRADUAL
DECREASE IN COVERAGE ACROSS THE AREA.
TEMPERATURES THROUGH THE PERIOD WILL EXPERIENCE LITTLE VARIATION
SUNDAY THROUGH TUESDAY. IT WILL NOT BE UNTIL TUESDAY NIGHT HEADING
INTO EARLY WEDNESDAY THAT A CHANGE TOWARD A SLIGHTLY DRIER...AND
THUS COOLER...AIRMASS TAKES PLACE.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 130 PM EDT FRIDAY...
LITTLE CHANGE IN THE LONG WAVE 500 MB PATTERN THROUGHOUT THIS TIME
PERIOD... WITH A RIDGE OVER THE WESTERN UNITED STATES AND TROUGHING
OVER THE EAST. MODELS NOT SHOWING GOOD TRENDS ON HOW AMPLIFIED
EASTERN TROF WILL BE.
MAIN SHORT WAVE ENERGY STAYS NORTH OF THE FORECAST AREA...BUT
WEAKER SHORT WAVES AROUND THE SOUTHERN EDGE OF THE TROF...ALONG
WITH LOW LEVEL CONVERGENCE ALONG ANY BOUNDARIES WILL PROVIDE
ENOUGH LIFT FOR THE RELATIVELY WET PATTERN TO CONTINUE.
WILL HAVE HIGHEST PROBABILITY OF PRECIPITATION IN THE AFTERNOON
AND EVENING ON THURSDAY AND FRIDAY WHEN SURFACE HIGH PRESSURE
MOVES OFFSHORE AND RETURN FLOW AROUND THE HIGH BRINGS MOISTURE
BACK INTO THE CENTRAL AND SOUTHERN APPALACHIANS.
TEMPERATURES BEHIND THE FRONT ON TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT WILL BE BELOW NORMAL...BUT HOW COOL THEY GET WILL DEPEND ON
THE AMPLITUDE OF THE TROF AND HOW FAR 850 MB FRONT ADVANCES SOUTH OF
THE FORECAST AREA.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 745 AM EDT SATURDAY...
SHOWERS MOVING INTO THE LWB-BLF CORRIDOR THIS MORNING MAY BRING
VSBYS/CIGS DOWN TO IFR OR LOWER BEFORE THE MIXING KICKS IN AND
CIGS RISE. AT THE MOMENT THE MODELS HAVE THE PRECIP AROUND THROUGH
MOST OF THE DAY AT BLF/LWB WITH PERIODS OF MODERATE TO HEAVY RAIN.
FOR NOW I AM HESITANT TO GO TO LOW ON VSBYS/CIGS AND HAVE -SHRA
AND VCTS.
FURTHER EAST WE WILL SEE SHOWERS AND STORMS FIRE UP IN THE 15-19Z
TIME FRAME WITH DANVILLE LAST TO SEE SHOWERS. AS WITH ANY STORM
HEAVY RAIN WILL BRING SOME IFR CIGS/VSBYS BUT EXPECT THAT VFR WILL
BE THE RULE MOST OF THE TIME.
TONIGHT...THE MODELS KEEP THE THREAT OF SHOWERS AROUND OVER THE
ENITRE CWA ESPECIALL ALONG AND SOUTH FROM BLF-BCB-DAN.
EXTENDED DISCUSSION...THE FRONT SHIFTS SLOWLY SOUTHEAST THRU THE
WEEKEND AND KEEPS THE THREAT OF SHOWERS/STORMS AROUND. THE FRONT
MAY SLIP SOUTH OF THE AREA BY MONDAY...BUT RETURN NORTH AS A WARM
FRONT BY TUESDAY AS ANOTHER FRONT/TROUGH APPROACH FROM THE NW.
POTENTIAL FOR SHRA/TSRA ANY DAY AT DAN...POSSIBLY A BREAK
LWB/BLF/BCB MON...BUT RETURNING BY TUE TO ALL AREAS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/WP
NEAR TERM...WP
SHORT TERM...DS
LONG TERM...AMS
AVIATION...WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
406 AM EDT SAT AUG 10 2013
.SYNOPSIS...
UNSETTLED PATTERN TO CONTINUE THROUGH THE WEEKEND AS FRONT STAYS
SITUATED ACROSS THE MID ATLANTIC INTO THE MID MISSISSIPPI VALLEY.
THE FRONT WEAKENS MONDAY WITH ANOTHER FRONT SHIFTING ACROSS OUR
REGION TUESDAY. HIGH PRESSURE WILL BUILD ACROSS TO OUR NORTH MID
TO LATE NEXT WEEK BUT ENOUGH MOISTURE SITUATED ACROSS THE
SOUTHEAST WILL KEEP THE THREAT OF SHOWERS AND STORMS AROUND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM EDT SATURDAY...
UPPER TROUGH ACROSS THE GREAT LAKES AND MID MS VALLEY EXPECTED TO
TRACK EAST WITH MID LEVEL SHORTWAVES MOVING ACROSS WHILE A FRONT
SLOWLY SAGS SOUTHWARD INTO OUR AREA BY SUNDAY. FOR THIS MORNING WE
ARE SEEING SOME HEAVY RAIN SHOWERS/EMBEDDED THUNDER ACROSS THE FAR
SW VA CORRIDOR INTO PORTIONS OF NW NC. THIS IN ASSOCIATION WITH SFC
THETA-E CONVERGENCE ALONG WITH PREFRONTAL TROUGH. THE LATEST RAP/RUC
SHOWING THAT ACTIVITY SWINGS EAST THROUGH DAWN INTO THE PIEDMONT
ALTHOUGH SOME WEAKENING IN THE NEW RIVER VALLEY APPEARS TO LIMIT
WHAT THE RAP SHOWS. FURTHER UPSTREAM CONVECTION ACROSS KY/WV SHOULD
SETTLE TOWARD THE SOUTHEAST WV AREA BY DAWN AS WELL.
THE FORECAST AND MODELS THE LAST FEW DAYS ADVERTISED HIGH POPS WHICH
HAS NOT WORKED OUT AT TIMES BUT WITH IMPROVING LOW LVL CONVERGENCE
AND PROXIMITY OF UPPER SHORTWAVE AM HESITANT TO KEEP POPS LOW
TODAY. I LEANED TOWARD THE RAP THIS MORNING BUT TRANSITIONED
TOWARD THE GFS THIS AFTERNOON BLENDED WITH THE PREVIOUS FORECAST.
AM THINKING THE CORRIDOR ALONG I-64 EAST INTO THE SHENANDOAH
VALLEY WILL BE ACTIVE LATE THIS MORNING INTO EARLY AFTERNOON WITH
DENSITY OF STORMS SHIFTING CONVECTION WITH OUTFLOW SOUTHEAST INTO
THE FOOTHILLS AND PIEDMONT THIS AFTERNOON. SO FOR NOW WILL HAVE
INCREASING POPS IN THE NORTH GOING TOWARD LIKELY BY MIDDAY THEN
SHIFTING HIGHER POPS SWD THRU THE AFTERNOON. NOT GOING TO PLAY
WITH 30 VS 50-60 POPS AS AIRMASS SOUPY ENOUGH AND PLENTY OF LIFT
WITH SOME UPPER SUPPORT THE HIGHER POPS AREA WIDE.
AGAIN...THINNING OUT OF CLOUDS SHOULD ALLOW SOME SUN TO HEAT
THINGS UP ALTHOUGH JUST GOING TO BE ENOUGH CLOUD COVER ALL DAY TO
PREVENT THE TEMPS FROM WARMING TOO HIGH UNLIKE WHAT HAPPENED
FRIDAY. WENT MORE TOWARD MET MOS EAST WHICH HAS NEAR 90 WHICH IS
BETWEEN THE COOLER ECMWF AND WARMER MAV. WITH CONVECTION AND
CLOUDS MORE PREVALENT OVER THE NORTHWEST WENT THE COOLER
MET...WITH UPPER 70S TO LOWER 80S.
THOUGH HEAVY RAIN THREAT REMAINS...THE ISOLATED FLASH FLOOD THREAT
REMAINS THAT A WATCH IS NOT NEEDED YET...BUT WILL HAVE TO SEE HOW
STORMS LINE UP THIS AFTERNOON TO SEE IF WE NEED ONE. THERE IS ALSO A
SMALL RISK OF SVR STORMS WITH THE SRN BELT OF WESTERLIES ALLOWING
FOR SOME WIND THREAT.
SHOULD SEE SOME COVERAGE ENTERING TONIGHT AS MODELS KEEP SHORTWAVE
ENERGY MOVING FROM WV/KY INTO NRN VA. MODELS ARE SHOWING MORE
AGREEMENT IN HAVING BEST CHANCE WEST AND AND NORTH...ALTHOUGH SOME
SHIFT IT SOUTH INTO THE NC/VA BORDER AREA AS WEAK LOW MOVES ACROSS.
AT THIS TIME HAVE LIKELY POPS IN THE EARLY EVENING TAPERING TO 40-50
BY MIDNIGHT...WITH NO FOCUSED AREA FOR HIGHER OR LOWER POPS...AS
LOSS OF HEATING EXPECTED TO RESULT IN MORE SCATTERED COVERAGE.
STILL MUGGY WITH DRIER AIR WELL NORTH ACROSS WRN PA/NY INTO THE
GREAT LAKES STATES. LOWS WILL RANGE FROM THE MID TO UPPER 60S ACROSS
THE WEST TO AROUND 70 AT ROANOKE AND POINTS EAST.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
AS OF 320 AM EDT SATURDAY...
THE AREA WILL CONTINUE WITHIN A PROGRESSIVE REGIME WITH DISTINCT
BOUTS OF HEAVY SHOWER AND THUNDERSTORM CHANCES. THE FIRST OF THESE
WILL BE DURING THE DAY SUNDAY WHEN A COLD FRONT PASSES THROUGH THE
REGION. MOST OF THE ACTIVITY WILL HEAD SOUTH OF THE AREA BY SUNDAY
EVENING. SURFACE HIGH PRESSURE BUILDS IN BEHIND THE FRONT BRIEFLY BY
MONDAY MORNING. HOWEVER...THE AXIS OF THIS HIGH/RIDGE WILL SHIFT
EAST OF THE AREA BY MONDAY MORNING...AND THUS ALLOW FOR SOUTHEAST
LOW LEVEL FLOW TO BRING LINGERING MOISTURE BACK INTO THE SOUTHWEST
PARTS OF THE FORECAST AREA. REGIONS ALONG THE CREST OF THE BLUE
RIDGE FROM ROUGHLY FLOYD VA SOUTHWEST INTO THE NORTHERN MOUNTAINS OF
NC WILL HAVE THE GREATEST POTENTIAL FOR SHOWERS AND A FEW
THUNDERSTORMS ON MONDAY.
BY MONDAY EVENING...THERE WILL BE A DECREASE IN COVERAGE OF THE
PRECIPITATION WILL THE LOSS OF DAYTIME HEATING. HOWEVER...OUR NEXT
APPROACHING COLD FRONT WILL START TO ALLOW FOR A RETURN OF ISOLATED
TO SCATTERED SHOWERS ACROSS THE FAR WESTERN PARTS OF THE REGION BY
SUNRISE TUESDAY. DURING THE DAY TUESDAY THIS FRONT WILL CROSS THE
AREA WITH A GOOD COVERAGE OF SHOWERS AND STORMS. SHOWERS ARE LIKELY
WITH SCATTERED THUNDERSTORMS ALONG AND EAST OF THE CREST OF THE BLUE
RIDGE BY TUESDAY AFTERNOON. TUESDAY NIGHT THERE WILL BE A GRADUAL
DECREASE IN COVERAGE ACROSS THE AREA.
TEMPERATURES THROUGH THE PERIOD WILL EXPERIENCE LITTLE VARIATION
SUNDAY THROUGH TUESDAY. IT WILL NOT BE UNTIL TUESDAY NIGHT HEADING
INTO EARLY WEDNESDAY THAT A CHANGE TOWARD A SLIGHTLY DRIER...AND
THUS COOLER...AIRMASS TAKES PLACE.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 130 PM EDT FRIDAY...
LITTLE CHANGE IN THE LONG WAVE 500 MB PATTERN THROUGHOUT THIS TIME
PERIOD... WITH A RIDGE OVER THE WESTERN UNITED STATES AND TROUGHING
OVER THE EAST. MODELS NOT SHOWING GOOD TRENDS ON HOW AMPLIFIED
EASTERN TROF WILL BE.
MAIN SHORT WAVE ENERGY STAYS NORTH OF THE FORECAST AREA...BUT
WEAKER SHORT WAVES AROUND THE SOUTHERN EDGE OF THE TROF...ALONG
WITH LOW LEVEL CONVERGENCE ALONG ANY BOUNDARIES WILL PROVIDE
ENOUGH LIFT FOR THE RELATIVELY WET PATTERN TO CONTINUE.
WILL HAVE HIGHEST PROBABILITY OF PRECIPITATION IN THE AFTERNOON
AND EVENING ON THURSDAY AND FRIDAY WHEN SURFACE HIGH PRESSURE
MOVES OFFSHORE AND RETURN FLOW AROUND THE HIGH BRINGS MOISTURE
BACK INTO THE CENTRAL AND SOUTHERN APPALACHIANS.
TEMPERATURES BEHIND THE FRONT ON TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT WILL BE BELOW NORMAL...BUT HOW COOL THEY GET WILL DEPEND ON
THE AMPLITUDE OF THE TROF AND HOW FAR 850 MB FRONT ADVANCES SOUTH OF
THE FORECAST AREA.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
AS OF 145 AM EDT SATURDAY...
SHOWERS WILL BE AFFECTING OR AT LEAST BE IN THE VICINITY OF THE
ROA/BCB/BLF/LWB TAF SITES THIS MORNING WITH CIGS/VSBYS SHIFTING
FROM VFR TO OCCASIONAL IFR WITH FOG.
FURTHER EAST WITH LESS STRATOCU WILL SEE LYH/DAN GET TO IFR VSBYS
AND/OR POSSIBLY CIGS AS WELL IN THE 09-12Z TIME FRAME.
AS WE HEAD INTO THE MORNING THE MODELS SHOWING GOOD THREAT OF
SHOWERS AND MOVING INTO MIDDAY/AFTERNOON THUNDERSTORMS. PROXIMITY
OF FRONT AND UPPER DISTURBANCE LEADS TO MODERATE CONFIDENCE THAT
ALL SITES GET SOME SHOWERS WITH THUNDER IN VICINITY. STILL TOO
EARLY TO PINPOINT AND ADD THUNDER TO PREDOMINANT WX GROUP BUT
BELIEVE THIS WILL CHANGE AS WE HEAD CLOSER TO MIDDAY. STILL LOOKS
LIKE OVERALL CIGS/VSBYS WILL BE VFR OUTSIDE OF CONVECTION.
TONIGHT...THE MODELS KEEP THE THREAT OF SHOWERS AROUND OVER THE
SOUTHERN HALF OF THE CWA FROM BLF-BCB-DAN SOUTH. WILL MAINTAIN
SOME VCSH AT LEAST INTO THE PIEDMONT AND BCB...BUT DRY IT OUT
ROA/BLF/LWB. WITH DEFINITE SHIFT SOUTH...THINK FOG WILL FORM IN
THE CLEARING AREAS NORTH SO OVERALL BY 06Z LWB/BLF SHOULD DROP TO
3SM.
EXTENDED DISCUSSION...THE FRONT SHIFTS SLOWLY SOUTHEAST THRU THE
WEEKEND AND KEEPS THE THREAT OF SHOWERS/STORMS AROUND. THE FRONT
MAY SLIP SOUTH OF THE AREA BY MONDAY...BUT RETURN NORTH AS A WARM
FRONT BY TUESDAY AS ANOTHER FRONT/TROUGH APPROACH FROM THE NW.
POTENTIAL FOR SHRA/TSRA ANY DAY AT DAN...POSSIBLY A BREAK
LWB/BLF/BCB MON...BUT RETURNING BY TUE TO ALL AREAS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/WP
NEAR TERM...WP
SHORT TERM...DS
LONG TERM...AMS
AVIATION...WP
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
935 PM CDT SUN AUG 11 2013
.UPDATE...POTENTIAL FOR DENSE FOG INCREASING IN FAR NORTH AS
11-3.9 MICRON IMAGERY HAS CLEARING LINE VERY CLOSE TO BORDER WITH
WAUSHARA COUNTY WHERE KY50 VSBY HAS DROPPED TO NEAR ZERO. HENCE WL
ISSUE DENSE FOG ADVY FOR MARQUETTE AND GREEN LAKE COUNTIES FOR
AFT MIDNIGHT INTO THE EARLY MORNING WHEN AT LEAST PARTIAL CLEARING
IS EXPECTED.
&&
.PREV DISCUSSION... /ISSUED 841 PM CDT SUN AUG 11 2013/
UPDATE...NEIGHBORHOOD WIND PROFILERS CONTINUE TO SHOW WEAK
UPSTREAM LOW TO MID LEVEL SHORT WAVE TROUGH OVER TRI-STATE AREA.
WEAK FORCING FROM THIS FEATURE ALONG WITH ISENTROPIC UPGLIDE ON
305 THETA SURFACE SHOULD RESULT IN SCT TO NUMEROUS -SHRA AND ISOLD
T AFFECTING MAINLY SOUTHERN THREE TIERS OF CWA OVERNIGHT. CLEARING
BEHIND SHORT WAVE...LIGHT WINDS AND HIGHER LOW LEVEL MOISTURE MAY
ALLOW DENSE FOG TO DEVELOP IN THE NORTH AFTER MIDNIGHT. WILL ADD
MENTION IN HWO BUT HOLD OFF ON ADVY FOR NOW.
AVIATION/06Z TAFS/...STILL SMALL THREAT FOR T OVERNIGHT AS WEAK
FORCING MOVES ACROSS THE AREA. CIGS MAY ALSO LOWER TO MVFR FOR A
TIME LATE TONIGHT IN LIGHT WIND REGIME AND WEAK CONVERGENCE.
LINGERING CLOUDS OVER TAF SITES SHOULD PRECLUDE SIGNIFICANT FOG
DEVELOPMENT.
PREV DISCUSSION... /ISSUED 345 PM CDT SUN AUG 11 2013/
SHORT TERM...
TONIGHT...FORECAST CONFIDENCE MEDIUM.
A FEW SHOWERS AND THUNDERSTORMS HAVE BEEN PERSISTENT ALONG THE MN/IA
BORDER TODAY. THEY ARE COINCIDENT WITH DEEP LAYER MOISTURE FLUX
CONVERGENCE... 850MB FRONTOGENESIS... WEAK DIFFERENTIAL VORTICITY
ADVECTION... AND UPPER DIVERGENCE ASSOCIATED WITH THE RIGHT ENTRANCE
REGION OF THE UPPER JET. THESE FEATURES WILL SLOWLY TRACK EASTWARD
ACROSS SOUTHERN WISCONSIN TONIGHT. IN ADDITION...A DECENT SURFACE
BAROCLINIC ZONE HAS SET UP OVER SOUTHERN WI DUE TO THE EXTENSIVE
CLOUD COVER. THERE IS A TIGHT TEMPERATURE GRADIENT RIGHT ALONG THE
WI/IL BORDER.
THE HRRR AND OTHER MESOSCALE MODELS ARE ALL CURRENTLY OVERDOING THE
PRECIP GOING ON IN IA/MN RIGHT NOW...SO LOW CONFIDENCE IN THEIR
PREDICTION OF WIDESPREAD COVERAGE FOR TONIGHT. NONETHELESS...THERE
IS ENOUGH PERSISTENT FORCING TO HAVE LIKELY SHOWERS AND ISOLATED
THUNDER IN THE FORECAST ACROSS SOUTHERN WI...MAINLY ALONG AND SOUTH
OF I-94...FOR MOST OF THE NIGHT. CHANCES WILL TAPER OFF FROM WEST TO
EAST AFTER MIDNIGHT.
FOG IS LOOKING LIKELY FOR TONIGHT. ORIGINALLY...A COLD FRONT WAS
GOING TO BE DROPPING DOWN TONIGHT...BUT THAT IS LOOKING DELAYED
UNTIL TOMORROW NOW. WINDS WILL BE LIGHT AND THERE IS ADDED LOW LEVEL
MOISTURE FROM THIS MORNING/S RAIN OVER ALL OF SOUTHERN WISCONSIN.
WITH DEWPOINT TEMPS SITTING IN THE LOWER 60S...EXPECTING A SMALL
SPREAD TONIGHT. DENSE FOG WILL BE POSSIBLE...ALTHOUGH THAT WOULD
REQUIRE A PERIOD OF CLEAR SKIES. NOT SURE HOW FAR SOUTH THAT
NORTHERN EDGE OF THE CLOUD SHIELD WILL SINK TONIGHT... SO NOT
CONFIDENT ENOUGH TO ISSUE A DENSE FOG ADVISORY FOR ANY PARTICULAR
AREA AT THIS TIME.
MONDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
A COLD FRONT WILL DROP DOWN ACROSS SOUTHERN WI ON MONDAY. IT LOOKS
LIKE IT WILL COME IN TWO WAVES...WITH A WEAK SURFACE FRONT WITH
WINDS BECOMING NORTH EARLY MONDAY MORNING...AND THEN A PUSH OF
COLDER AIR LATE MONDAY AFTERNOON. THAT SECOND PUSH IS EXPECTED TO
RUSH DOWN THE LAKE A LITTLE FASTER THAN INLAND...ALSO KNOWN AS A
BACK DOOR COLD FRONT...AND BRING SOME STRONGER WINDS WITH IT.
THERE WILL BE STEEP LOW LEVEL LAPSE RATES AND CYCLONIC FLOW ALOFT
WHICH WILL HELP CLOUDS DEVELOP DURING THE DAY. THERE MAY BE JUST
ENOUGH MOISTURE AROUND IN THE EASTERN MKX FORECAST AREA TO ALLOW FOR
SCATTERED SHOWERS. WHILE THE CHANCE IS SMALL...THERE COULD BE A FEW
RUMBLES OF THUNDER AS WELL. CLOUDS WILL KEEP EASTERN MKX AREA A
LITTLE COOLER IN THE MID 70S...WHILE BREAKS IN THE CLOUDS SHOULD
ALLOW WESTERN AREAS TO WARM UP TO AROUND 80.
LONG TERM...
MONDAY NIGHT - CONFIDENCE...MEDIUM
SHORT-WAVE TROUGH SWINGS SOUTHEAST THROUGH MY COUNTY WARNING AREA
MONDAY NIGHT. NORMALLY...ONE WOULD THINK OF HAVING AT LEAST A LOW-
CHANCE PROBABILITIES OF MEASURABLE PRECIP WITH A TROUGH.
HOWEVER...MODELS DON/T SHOW MUCH MOISTURE ABOVE 10 THSD FT AGL IN
THE TIME SECTIONS. IN FACT THEY SHOW DRYING TO VARYING DEGREES.
WITH THE LACK OF SATURATION IN THE -10 TO -20C LAYER OF
AIR...CAN/T SEE PRECIPITATION. THE NAM/ECWMF HAVE MY CWA DRY...AND
GFS SPITS OUT A COUPLE SHOWERS. WILL KEEP FORECAST DRY.
TUESDAY THROUGH THURSDAY - CONFIDENCE...MEDIUM
LARGE COOL HIGH PRESSURE DROPS SOUTHEAST TROUGH GREAT LAKES REGION.
QUIET WEATHER. CAN SEE SOME FOG IN RIVER VALLEYS...SO PUT THAT INTO
THE GRID FORECASTS. THE NAM/GFS MODELS SUGGEST ISOLATED SHOWERS
TUESDAY THROUGH THURSDAY WITH HEATING DURING THE DAY. THIS LOOKS TO
TO SOME KIND OF NOISE SINCE THE BUFKIT SOUNDINGS SHOW A PERSISTENT
SUBSIDENCE INVERSION BETWEEN 10 AND 15 THSD FT DURING THIS TIME THAT
CAPS ANY MIXED BOUNDARY LAYER AIR FROM RISING UPWARD. SO WILL KEEP
DRY DURING THIS PERIOD.
FRIDAY THROUGH SUNDAY - CONFIDENCE...MEDIUM
GFS SUGGESTS CHANCES FOR PRECIPITATION ON FRIDAY AS A SHORTWAVE
TROUGH AND VORTMAX DROP INTO AND ATTEMPT TO CLOSE OFF OVER SOUTHERN
WISCONSIN. ECMWF IS SIMILAR BUT WEAKER...AND KEEPS THINGS DRY. BOTH
THE GFS AND ECMWF HAVE MID-LEVEL DRY AIR ON FRIDAY...SUGGESTING
MID-LEVEL SUBSIDENCE INVERSION HANGS TOUGH. RATHER THAN YO-YO ON
THE FORECAST...WILL KEEP HOLDING OFF ON CHANCE FOR PRECIPITATION. IT
IS EVEN POSSIBLE THE CLOSING-OFF IDEA WILL OCCUR SOUTH OF WISCONSIN
ANYWAY.
SURFACE HIGH PRESSURE EXTENSION FROM EAST COAST BACK TO ILLINOIS/WI
AREA PER MODEL FORECAST SUGGESTS DRY FOR SATURDAY AND SUNDAY.
AVIATION/00Z TAFS/...
AN AREA OF SHOWERS WITH A FEW THUNDERSTORMS OVER NORTHERN IOWA WILL
SLOWLY WORK THEIR WAY EASTWARD ACROSS SOUTHERN WI OVERNIGHT. NOT
QUITE CERTAIN ABOUT COVERAGE...BUT THEY SHOULD AT LEAST BE
SCATTERED...IF NOT NUMEROUS. CEILINGS AND VISIBILITIES WILL LOWER
INTO MVFR RANGE WITH AREAS OF FOG AND SCATTERED SHOWERS/THUNDER.
SCATTERED SHOWERS AND ISOLATED THUNDER POSSIBLE ONCE AGAIN MONDAY
AFTERNOON MAINLY EAST OF MADISON WITH A COLD FRONT DROPPING DOWN
ACROSS WISCONSIN.
MARINE...
A COLD FRONT PUSHES SOUTH MONDAY WITH WINDS TURNING TO THE NORTH AND
THEN NORTHEAST ACROSS LAKE MICHIGAN. PRESSURE RISES ON THE ORDER OF
3 MB/6 HOURS AND DECENT COLD ADVECTION SHOULD KICK UP WINDS AT LEAST
INTO 15 KNOT RANGE. FAVORABLE FETCH MONDAY NIGHT THROUGH TUESDAY
WITH SPEEDS APPROACHING SMALL CRAFT LEVELS SHOULD GENERATE DECENT
WAVES ESPECIALLY FROM MILWAUKEE ON SOUTH. RIGHT NOW LOOKING AT
ABOUT 4 FOOT WAVES LATE MONDAY NIGHT THROUGH TUESDAY AND THESE MAY
LINGER INTO TUESDAY NIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY FROM 1 AM TO 9 AM CDT MONDAY FOR WIZ046-047.
LM...NONE.
&&
$$
UPDATE...MBK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
934 PM CDT SUN AUG 11 2013
.UPDATE...OVERNIGHT
ISSUED AT 934 PM CDT SUN AUG 11 2013
WORKING ON AN UPDATE TO THE DENSE FOG ADVISORY TO INCLUDE CLARK
COUNTY AND WILL ALSO BUMP UP THE START TIME. UPPING THE START TIME
SINCE DENSE FOG IS QUICKLY FORMING IN CENTRAL WISCONSIN WITH SKIES
CLEARING. UPDATE COMING OUT SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 248 PM CDT SUN AUG 11 2013
MAIN FORECAST CONCERNS ARE ON PRECIPITATION TONIGHT AND DENSE FOG
POTENTIAL TONIGHT INTO MONDAY MORNING.
CURRENTLY...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER
MUCH OF THE U.S. AND CANADIAN ROCKIES...WHILE TROUGHING DOMINATED
SOUTHEAST CANADA. THE FORECAST AREA RESIDES IN WEST-NORTHWEST
FLOW...WITH SHORTWAVES OF NOTE OVER NORTHEAST IOWA...SOUTHERN
MANITOBA AND A MUCH STRONGER ONE OVER NORTHERN MANITOBA. THE
NORTHEAST IOWA SHORTWAVE...COMBINED WITH A LOW TO MID LEVEL
FRONTOGENESIS ZONE AND A RIGHT ENTRANCE REGION OF AN 80 KT UPPER
JET STREAK IN NORTHERN WI...HAS HELPED TO KEEP SOME SHOWER
ACTIVITY GOING ACROSS NORTHERN IOWA THROUGH THE AFTERNOON. ALSO
PLENTY OF CLOUDS EXIST ACROSS THE FORECAST AREA...RESULTING FROM
DEEP LOW LEVEL MOISTURE SEEN ON THE 12Z MPX SOUNDING AND THE LACK
OF MUCH WIND FLOW TO ADVECT DRIER AIR SEEN ACROSS NORTH DAKOTA AND
NORTHERN MN. THE DRIER AIR LIES BEHIND A SURFACE TROUGH STRETCHING
FROM EASTERN NEBRASKA INTO NORTHWEST WI. A FEW SHOWERS HAVE FORMED
ON THIS TROUGH ACROSS EAST CENTRAL MN. FARTHER SOUTH...A WARM
FRONT ENHANCED BY OUTFLOW FROM THE SHOWERS WAS PRESENT STRETCHING
ALONG US-20 IN IOWA.
SYNOPTIC OVERVIEW...
FOCUS IS MOSTLY ON THE SHORTWAVE OVER NORTHERN MANITOBA. MODELS PROG
THIS SHORTWAVE TO DROP SOUTHEAST INTO UPPER MICHIGAN ON MONDAY. THIS
SHORTWAVE ALLOWS UPPER TROUGHING TO MOVE INTO THE FORECAST AREA...
AND SIMULTANEOUSLY HELPS GIVE THE SURFACE TROUGH IN MN A PUSH
SOUTHEAST. BY 12Z MONDAY...THE TROUGH...LIKELY NOW A COLD
FRONT...SHOULD BE SOUTHEAST OF THE AREA. THERE ARE ALSO
INDICATIONS OF AN INVERTED SURFACE TROUGH LINGERING BACK EXTENDING
NORTHWEST TO SOUTHEAST OVER CENTRAL/EASTERN WI...ASSOCIATED WITH
THAT SHORTWAVE DROPPING INTO UPPER MI.
HAZARDS...
DENSE FOG CONCERNS TONIGHT GIVEN RECENT RAINS...LIGHT WINDS...LATE
DAY CLEARING AND SMALL TEMP/DEW POINT SPREADS ALREADY.
DETAILS...
SHOWERS IN EAST CENTRAL MINNESOTA MAY TRY TO DROP DOWN INTO
NORTHWESTERN SECTIONS OF THE FORECAST AREA THIS EVENING.
HOWEVER...THEY ARE HIGHLY DIURNALLY DRIVEN...THUS ONCE HEATING
ENDS THEY SHOULD FALL APART QUICKLY. INCLUDED SOME 20 PERCENT
CHANCES FOR THEM FOR A FEW HOURS THIS EVENING. MEANWHILE...TO THE
SOUTH...ONGOING SHOWERS AND STORMS ACROSS NORTHEAST IOWA MAY
PERSIST THROUGH MUCH OF THE EVENING...SUPPORTED BY THE SHORTWAVE
TRACKING ACROSS NORTHEAST IOWA...THE LOW/MID LEVEL F-GEN AND RIGHT
ENTRANCE REGION. HOWEVER...AS THE UPPER FLOW TURNS MORE
NORTHWESTERLY... ANTICIPATING THESE FORCING FEATURES TO DROP
SOUTHEAST AND HELP DIMINISH THE PRECIPITATION. DID KEEP 20-40
PERCENT CHANCES GOING AFTER MIDNIGHT JUST IN CASE PRECIP HOLDS
ON A BIT LONGER THAN EXPECTED.
CONCERN THEN SHIFTS TO FOG GIVEN RECENT RAIN. CLOUDS OVER THE
FORECAST AREA...PARTICULARLY OVER THE NORTHERN HALF...SHOULD CLEAR
OUT THIS EVENING. WINDS LOOK TO STAY FAIRLY LIGHT THROUGH THE
NIGHT...EVEN AFTER THE TROUGH/FRONTAL PASSAGE. ITS WORTH NOTING
THAT WINDS DO PICK UP AT 950MB INTO THE 10-20 KT RANGE BY 12Z...
HOWEVER...THESE ARE ABOVE A 3C FRONTAL INVERSION. THUS...THEY SHOULD
NOT IMPACT THE FOG POTENTIAL MUCH. IN FACT...11.00Z/06Z/12Z HIRES
ARW/NMM AND 11.09Z SREF VISIBILITY PROGS SHOW PRETTY MUCH A SOLID
AREA OF FOG OVER SOUTHEAST MN...NORTHERN PARTS OF IOWA AND MUCH OF
SOUTHERN WI. ADDED MENTION OF FOG EARLIER ACROSS MUCH OF THE
FORECAST AREA...AND NOW HAVE RAISED THE COVERAGE TO WIDESPREAD IN A
CORRIDOR FROM SOUTHEAST MINNESOTA EAST INTO JACKSON...JUNEAU...ADAMS
AND VERNON COUNTIES OF WI. THIS AREA HAS ALSO BEEN INCLUDED IN A
DENSE FOG ADVISORY...SINCE FROM A REGIONAL PERSPECTIVE SEEMS TO
HAVE THE HIGHEST PROBABILITY OF METEOROLOGICAL CONDITIONS
FAVORABLE FOR DENSE FOG. THE ADVISORY MAY HAVE TO BE EXPANDED
SOUTH...ESPECIALLY IF SKIES END UP CLEARING THERE.
FOR MONDAY...COOLER AIR ALOFT UNDER THE UPPER TROUGHING COMBINED
WITH THE INVERTED SURFACE TROUGH...DAYTIME HEATING AND LINGERING LOW
LEVEL MOISTURE SHOULD ALLOW FOR ISOLATED/SCATTERED SHOWERS TO FORM
ALONG/NORTHEAST OF I-94. MLCAPE VALUES ALONG THE INVERTED TROUGH ARE
IN THE 100-300 J/KG AT 18Z...ENOUGH MAYBE TO GET A FEW
THUNDERSTORMS. BETTER INSTABILITY IS OFF TOWARDS SOUTHEAST WI WITH
HELP FROM LAKE BREEZE CONVERGENCE. ONCE THE FOG AND ASSOCIATED LOW
STRATUS MIX OUT A FEW HOURS AFTER SUNRISE...RELATIVELY BREEZY
NORTHWEST WINDS APPEAR TO SET UP. 850MB TEMPS IN THE 10-14C RANGE
SUPPORT HIGHS IN THE MID 70S TO LOW 80S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN AUG 11 2013
MUCH OF THE ENTIRE LONG TERM PERIOD IS DOMINATED BY RIDGING OVER THE
WESTERN U.S. AND TROUGHING IN THE EASTERN U.S....A POSITIVE PNA
PATTERN THAT RESULTS IN COOLER AND DRIER THAN NORMAL WEATHER. AT THE
SURFACE...CANADIAN HIGH PRESSURE IS PROGGED TO BUILD INTO THE AREA
MONDAY NIGHT AND TUESDAY...SIT OVER THE AREA TUESDAY NIGHT THROUGH
WEDNESDAY...THEN ONLY SLOWLY DRIFT OFF TOWARDS THE EASTERN GREAT
LAKES THIS WEEKEND. DRY AIR ACCOMPANYING THE HIGH LOOKS TO KEEP THE
BULK OF THE LONG TERM PERIOD DRY. IN FACT...PRECIPITABLE WATER
VALUES ARE FORECAST BETWEEN 50-70 PERCENT OF NORMAL FOR TUESDAY
THROUGH THURSDAY. THIS SHOULD RESULT IN DECENT MIXING OF DEW POINTS
DURING THE AFTERNOONS.
THE ONLY FEATURE REALLY OF INTEREST FOR POTENTIAL PRECIPITATION IS A
SHORTWAVE TROUGH THAT DROPS DOWN THROUGH THE NORTHWEST FLOW INTO THE
AREA THURSDAY NIGHT AND FRIDAY. BOTH THE 11.12Z GFS/CANADIAN PRODUCE
SOME LIGHT PRECIPITATION WITH IT OVER WESTERN AND NORTHERN SECTIONS
OF THE FORECAST AREA...WHEREAS THE 11.00Z/11.12Z ECMWF IS DRY. FROM
A CONSENSUS STANDPOINT...HAVE CONTINUED TO CARRY A 20 PERCENT CHANCE
TO ACCOUNT FOR THE GFS/CANADIAN. HOWEVER...LATER FORECASTS WILL BE
ABLE TO GO DRY IF THE GFS/CANADIAN TREND TOWARDS THE ECMWF.
TEMPERATURE WISE...850MB TEMP ANOMALIES ARE PROGGED TO BOTTOM OUT
BETWEEN 1-1.5C BELOW NORMAL FOR TUESDAY AND WEDNESDAY...READINGS OF
8C EAST TO 10C WEST. THUS THIS WILL BE THE COLDEST PERIOD WITH HIGHS
IN THE 70S. LOWS ARE LIKELY GOING TO DIP INTO THE 40S AT THE TYPICAL
COLD SPOTS TUESDAY NIGHT AND WEDNESDAY NIGHT WITH THE HIGH
OVERHEAD...WHICH WILL ALSO BE THE MOST FAVORABLE TIME PERIODS FOR
VALLEY FOG. VALLEY FOG IS ALSO POSSIBLE MONDAY NIGHT...BUT WINDS
WITH THE INCOMING HIGH MAY RESTRICT SOME OF THE COVERAGE. SLOW
WARMING OF 850MB TEMPS AND ANOMALIES IS FORECAST FOR THURSDAY AND
BEYOND...PEAKING AT 12C EAST TO 15C WEST AND AROUND NORMAL FOR
ANOMALY BY SUNDAY. THUS TEMPERATURES SHOULD SLOWLY CLIMB TOO EACH
DAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 647 PM CDT SUN AUG 11 2013
THE MAIN FOCUS IS ON THE DENSE FOG EXPECTED OVERNIGHT. WITH CLOUDS
HOLDING TEMPERATURES DOWN THIS AFTERNOON AND THEN CLEARING THIS
EVENING...EXPECT THAT FOG WILL FORM RATHER QUICKLY AS SURFACE
WINDS HAVE ALREADY BECOME CALM WITH MOST AREAS SEEING SOME RAIN
TODAY. QUARTER MILE VISIBILITY IS FAIRLY LIKELY AFTER 6Z BEFORE
CLEARING AFTER SUNRISE TOMORROW MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY FROM 3 AM TO 9 AM CDT MONDAY FOR WIZ032>034-
041>044-053.
MN...DENSE FOG ADVISORY FROM 3 AM TO 9 AM CDT MONDAY FOR MNZ079-
086>088-094>096.
IA...NONE.
&&
$$
UPDATE...HALBACH
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
647 PM CDT SUN AUG 11 2013
.UPDATE...THIS EVENING/OVERNIGHT
ISSUED AT 647 PM CDT SUN AUG 11 2013
CONVECTION HAS DEVELOPED FROM SOUTHEAST MINNESOTA DOWN THROUGH
NORTHEAST TO WEST CENTRAL IOWA ALONG A MID LEVEL TROUGH AND
SURFACE WARM FRONT/LOW PRESSURE SYSTEM. THE MOST VIGOROUS
CONVECTION HAS BEEN CLOSER TO THE WARM FRONT FROM IOWA FALLS TO
WATERLOO WHERE INSTABILITY IS ALSO HIGHER PER 11.23Z RAP ANALYSIS.
0-3KM MUCAPE DROPS ABOUT 1000 J/KG ALONG THE BAND OF CONVECTION
JUST SOUTH OF THE MINNESOTA STATE LINE THOUGH WIND SHEAR IS STILL
MARGINAL AT ABOUT 35-45KT FROM 0-6KM. CAN NOT COMPLETELY RULE OUT
AN ISOLATED SEVERE STORM FOR FAYETTE/CLAYTON/GRANT COUNTIES THIS
EVENING AS THE STRONGEST LOOKING CELL TRACKS INTO THAT REGION OVER
THE NEXT FEW HOURS...BUT RADAR TRENDS FOR THE PAST FEW HOURS HAVE
SHOWN THAT THE LACK IN INSTABILITY HAS KEPT THESE CELLS FROM
GROWING ENOUGH TO REACH THAT SEVERE LEVEL. FURTHER NORTH IN
SOUTHEAST MINNESOTA...THERE APPEARS TO BE A WEAK BOUNDARY THAT
EXTENDS FROM CANNON FALLS TO MAZEPPA TO ST CHARLES OR ALONG THE
FAR WESTERN PARTS OF THE MINNESOTA COUNTIES ALONG THE MISSISSIPPI
RIVER. WHILE THESE SHOWERS LOOK INNOCENT ENOUGH ON RADAR WITH NO
ROTATION SHOWING UP IN THE VELOCITY FIELDS...THE BOUNDARY HAS BEEN
ENOUGH TO DEVELOP A FEW BRIEF FUNNEL CLOUDS. THESE CONDITIONS MAY
PERSIST FOR ANOTHER HOUR OR TWO BEFORE SKIES START TO CLEAR OUT.
NO CHANGES IN REGARD TO THE FOG AS SKIES ARE STILL EXPECTED TO
CLEAR OVERNIGHT WITH FOG FORMING RAPIDLY AS IT DOES. WINDS HAVE
ALREADY GONE CALM AND SATELLITE TRENDS SHOW A CLEARING TREND FROM
THE NORTH. THE PAST FEW RUNS OF THE HRRR CONTINUE TO SHOW DENSE
FOG FORMING AS WELL...BUT GO FURTHER SOUTH INTO IOWA WHERE THERE
HAS BEEN SOME DECENT RAINS THIS AFTERNOON/EVENING. SO...IF ANY
ADJUSTMENTS WILL NEED TO BE MADE THIS EVENING...IT MAY BE TO
EXTEND THE ADVISORY FURTHER SOUTH.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 248 PM CDT SUN AUG 11 2013
MAIN FORECAST CONCERNS ARE ON PRECIPITATION TONIGHT AND DENSE FOG
POTENTIAL TONIGHT INTO MONDAY MORNING.
CURRENTLY...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER
MUCH OF THE U.S. AND CANADIAN ROCKIES...WHILE TROUGHING DOMINATED
SOUTHEAST CANADA. THE FORECAST AREA RESIDES IN WEST-NORTHWEST
FLOW...WITH SHORTWAVES OF NOTE OVER NORTHEAST IOWA...SOUTHERN
MANITOBA AND A MUCH STRONGER ONE OVER NORTHERN MANITOBA. THE
NORTHEAST IOWA SHORTWAVE...COMBINED WITH A LOW TO MID LEVEL
FRONTOGENESIS ZONE AND A RIGHT ENTRANCE REGION OF AN 80 KT UPPER
JET STREAK IN NORTHERN WI...HAS HELPED TO KEEP SOME SHOWER
ACTIVITY GOING ACROSS NORTHERN IOWA THROUGH THE AFTERNOON. ALSO
PLENTY OF CLOUDS EXIST ACROSS THE FORECAST AREA...RESULTING FROM
DEEP LOW LEVEL MOISTURE SEEN ON THE 12Z MPX SOUNDING AND THE LACK
OF MUCH WIND FLOW TO ADVECT DRIER AIR SEEN ACROSS NORTH DAKOTA AND
NORTHERN MN. THE DRIER AIR LIES BEHIND A SURFACE TROUGH STRETCHING
FROM EASTERN NEBRASKA INTO NORTHWEST WI. A FEW SHOWERS HAVE FORMED
ON THIS TROUGH ACROSS EAST CENTRAL MN. FARTHER SOUTH...A WARM
FRONT ENHANCED BY OUTFLOW FROM THE SHOWERS WAS PRESENT STRETCHING
ALONG US-20 IN IOWA.
SYNOPTIC OVERVIEW...
FOCUS IS MOSTLY ON THE SHORTWAVE OVER NORTHERN MANITOBA. MODELS PROG
THIS SHORTWAVE TO DROP SOUTHEAST INTO UPPER MICHIGAN ON MONDAY. THIS
SHORTWAVE ALLOWS UPPER TROUGHING TO MOVE INTO THE FORECAST AREA...
AND SIMULTANEOUSLY HELPS GIVE THE SURFACE TROUGH IN MN A PUSH
SOUTHEAST. BY 12Z MONDAY...THE TROUGH...LIKELY NOW A COLD
FRONT...SHOULD BE SOUTHEAST OF THE AREA. THERE ARE ALSO
INDICATIONS OF AN INVERTED SURFACE TROUGH LINGERING BACK EXTENDING
NORTHWEST TO SOUTHEAST OVER CENTRAL/EASTERN WI...ASSOCIATED WITH
THAT SHORTWAVE DROPPING INTO UPPER MI.
HAZARDS...
DENSE FOG CONCERNS TONIGHT GIVEN RECENT RAINS...LIGHT WINDS...LATE
DAY CLEARING AND SMALL TEMP/DEW POINT SPREADS ALREADY.
DETAILS...
SHOWERS IN EAST CENTRAL MINNESOTA MAY TRY TO DROP DOWN INTO
NORTHWESTERN SECTIONS OF THE FORECAST AREA THIS EVENING.
HOWEVER...THEY ARE HIGHLY DIURNALLY DRIVEN...THUS ONCE HEATING
ENDS THEY SHOULD FALL APART QUICKLY. INCLUDED SOME 20 PERCENT
CHANCES FOR THEM FOR A FEW HOURS THIS EVENING. MEANWHILE...TO THE
SOUTH...ONGOING SHOWERS AND STORMS ACROSS NORTHEAST IOWA MAY
PERSIST THROUGH MUCH OF THE EVENING...SUPPORTED BY THE SHORTWAVE
TRACKING ACROSS NORTHEAST IOWA...THE LOW/MID LEVEL F-GEN AND RIGHT
ENTRANCE REGION. HOWEVER...AS THE UPPER FLOW TURNS MORE
NORTHWESTERLY... ANTICIPATING THESE FORCING FEATURES TO DROP
SOUTHEAST AND HELP DIMINISH THE PRECIPITATION. DID KEEP 20-40
PERCENT CHANCES GOING AFTER MIDNIGHT JUST IN CASE PRECIP HOLDS
ON A BIT LONGER THAN EXPECTED.
CONCERN THEN SHIFTS TO FOG GIVEN RECENT RAIN. CLOUDS OVER THE
FORECAST AREA...PARTICULARLY OVER THE NORTHERN HALF...SHOULD CLEAR
OUT THIS EVENING. WINDS LOOK TO STAY FAIRLY LIGHT THROUGH THE
NIGHT...EVEN AFTER THE TROUGH/FRONTAL PASSAGE. ITS WORTH NOTING
THAT WINDS DO PICK UP AT 950MB INTO THE 10-20 KT RANGE BY 12Z...
HOWEVER...THESE ARE ABOVE A 3C FRONTAL INVERSION. THUS...THEY SHOULD
NOT IMPACT THE FOG POTENTIAL MUCH. IN FACT...11.00Z/06Z/12Z HIRES
ARW/NMM AND 11.09Z SREF VISIBILITY PROGS SHOW PRETTY MUCH A SOLID
AREA OF FOG OVER SOUTHEAST MN...NORTHERN PARTS OF IOWA AND MUCH OF
SOUTHERN WI. ADDED MENTION OF FOG EARLIER ACROSS MUCH OF THE
FORECAST AREA...AND NOW HAVE RAISED THE COVERAGE TO WIDESPREAD IN A
CORRIDOR FROM SOUTHEAST MINNESOTA EAST INTO JACKSON...JUNEAU...ADAMS
AND VERNON COUNTIES OF WI. THIS AREA HAS ALSO BEEN INCLUDED IN A
DENSE FOG ADVISORY...SINCE FROM A REGIONAL PERSPECTIVE SEEMS TO
HAVE THE HIGHEST PROBABILITY OF METEOROLOGICAL CONDITIONS
FAVORABLE FOR DENSE FOG. THE ADVISORY MAY HAVE TO BE EXPANDED
SOUTH...ESPECIALLY IF SKIES END UP CLEARING THERE.
FOR MONDAY...COOLER AIR ALOFT UNDER THE UPPER TROUGHING COMBINED
WITH THE INVERTED SURFACE TROUGH...DAYTIME HEATING AND LINGERING LOW
LEVEL MOISTURE SHOULD ALLOW FOR ISOLATED/SCATTERED SHOWERS TO FORM
ALONG/NORTHEAST OF I-94. MLCAPE VALUES ALONG THE INVERTED TROUGH ARE
IN THE 100-300 J/KG AT 18Z...ENOUGH MAYBE TO GET A FEW
THUNDERSTORMS. BETTER INSTABILITY IS OFF TOWARDS SOUTHEAST WI WITH
HELP FROM LAKE BREEZE CONVERGENCE. ONCE THE FOG AND ASSOCIATED LOW
STRATUS MIX OUT A FEW HOURS AFTER SUNRISE...RELATIVELY BREEZY
NORTHWEST WINDS APPEAR TO SET UP. 850MB TEMPS IN THE 10-14C RANGE
SUPPORT HIGHS IN THE MID 70S TO LOW 80S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN AUG 11 2013
MUCH OF THE ENTIRE LONG TERM PERIOD IS DOMINATED BY RIDGING OVER THE
WESTERN U.S. AND TROUGHING IN THE EASTERN U.S....A POSITIVE PNA
PATTERN THAT RESULTS IN COOLER AND DRIER THAN NORMAL WEATHER. AT THE
SURFACE...CANADIAN HIGH PRESSURE IS PROGGED TO BUILD INTO THE AREA
MONDAY NIGHT AND TUESDAY...SIT OVER THE AREA TUESDAY NIGHT THROUGH
WEDNESDAY...THEN ONLY SLOWLY DRIFT OFF TOWARDS THE EASTERN GREAT
LAKES THIS WEEKEND. DRY AIR ACCOMPANYING THE HIGH LOOKS TO KEEP THE
BULK OF THE LONG TERM PERIOD DRY. IN FACT...PRECIPITABLE WATER
VALUES ARE FORECAST BETWEEN 50-70 PERCENT OF NORMAL FOR TUESDAY
THROUGH THURSDAY. THIS SHOULD RESULT IN DECENT MIXING OF DEW POINTS
DURING THE AFTERNOONS.
THE ONLY FEATURE REALLY OF INTEREST FOR POTENTIAL PRECIPITATION IS A
SHORTWAVE TROUGH THAT DROPS DOWN THROUGH THE NORTHWEST FLOW INTO THE
AREA THURSDAY NIGHT AND FRIDAY. BOTH THE 11.12Z GFS/CANADIAN PRODUCE
SOME LIGHT PRECIPITATION WITH IT OVER WESTERN AND NORTHERN SECTIONS
OF THE FORECAST AREA...WHEREAS THE 11.00Z/11.12Z ECMWF IS DRY. FROM
A CONSENSUS STANDPOINT...HAVE CONTINUED TO CARRY A 20 PERCENT CHANCE
TO ACCOUNT FOR THE GFS/CANADIAN. HOWEVER...LATER FORECASTS WILL BE
ABLE TO GO DRY IF THE GFS/CANADIAN TREND TOWARDS THE ECMWF.
TEMPERATURE WISE...850MB TEMP ANOMALIES ARE PROGGED TO BOTTOM OUT
BETWEEN 1-1.5C BELOW NORMAL FOR TUESDAY AND WEDNESDAY...READINGS OF
8C EAST TO 10C WEST. THUS THIS WILL BE THE COLDEST PERIOD WITH HIGHS
IN THE 70S. LOWS ARE LIKELY GOING TO DIP INTO THE 40S AT THE TYPICAL
COLD SPOTS TUESDAY NIGHT AND WEDNESDAY NIGHT WITH THE HIGH
OVERHEAD...WHICH WILL ALSO BE THE MOST FAVORABLE TIME PERIODS FOR
VALLEY FOG. VALLEY FOG IS ALSO POSSIBLE MONDAY NIGHT...BUT WINDS
WITH THE INCOMING HIGH MAY RESTRICT SOME OF THE COVERAGE. SLOW
WARMING OF 850MB TEMPS AND ANOMALIES IS FORECAST FOR THURSDAY AND
BEYOND...PEAKING AT 12C EAST TO 15C WEST AND AROUND NORMAL FOR
ANOMALY BY SUNDAY. THUS TEMPERATURES SHOULD SLOWLY CLIMB TOO EACH
DAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 647 PM CDT SUN AUG 11 2013
THE MAIN FOCUS IS ON THE DENSE FOG EXPECTED OVERNIGHT. WITH CLOUDS
HOLDING TEMPERATURES DOWN THIS AFTERNOON AND THEN CLEARING THIS
EVENING...EXPECT THAT FOG WILL FORM RATHER QUICKLY AS SURFACE
WINDS HAVE ALREADY BECOME CALM WITH MOST AREAS SEEING SOME RAIN
TODAY. QUARTER MILE VISIBILITY IS FAIRLY LIKELY AFTER 6Z BEFORE
CLEARING AFTER SUNRISE TOMORROW MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY FROM 3 AM TO 9 AM CDT MONDAY FOR WIZ032>034-
041>044-053.
MN...DENSE FOG ADVISORY FROM 3 AM TO 9 AM CDT MONDAY FOR MNZ079-
086>088-094>096.
IA...NONE.
&&
$$
UPDATE...HALBACH
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
355 AM MDT MON AUG 12 2013
.SHORT TERM...WATER VAPOR LOOP INDICATED A MOISTURE PLUME SHIFTING
NORTHEAST ACROSS COLORADO EARLY THIS MORNING. AT THE SURFACE...A
WEAK SURGE HAD PUSH ACROSS MOST OF THE PLAINS WITH A SLIGHT
INCREASE IN LOW LEVEL MOISTURE. HOWEVER...THIS MOISTURE WAS QUITE
SHALLOW AS PRECIPITABLE WATER VALUES HAD BARELY BUDGED OVER THE
LAST 24 HOURS. OVERALL...THE WEATHER PATTERN REMAINS QUITE SIMILAR
TO YESTERDAY WITH THE UPPER LEVEL RIDGE CENTERED OVER THE STATE.
HOWEVER...ONE FEATURE THAT MAY COME INTO PLAY IS AN UPPER LEVEL
SPEED MAX MOVING ACROSS THE DESERT SOUTHWEST. THE FORECAST AREA
WILL BE IN THE LEFT EXIT REGION OF THIS JET FROM THIS AFTERNOON
THROUGH TONIGHT. THERE WAS DEEP...PERSISTENT...BUT WEAK Q-G LIFT
NOTED IN MOST MODELS THROUGH TONIGHT. THIS SHOULD HELP INCREASE
CONVECTIVE COVERAGE A BIT FROM YESTERDAY. MEANWHILE...SHORT RANGE
MESOSCALE MODELS INCLUDING THE WRF AND HRRR SHOW THE TYPICAL START
TO CONVECTION ALONG THE FRONT RANGE MOUNTAINS AND FOOTHILLS BY
17Z-18Z...AND THEN SPREADING/DEVELOPING EASTWARD THROUGH THE
AFTERNOON HOURS. AT THIS POINT...SEE LITTLE REASON TO ARGUE WITH
THIS SCENARIO. THERE WILL BE A SLIGHT RISK OF ONE OR TWO STORMS
BRIEFLY REACHING SEVERE CRITERIA ON THE PLAINS WITH MARGINAL
HAIL/WIND.
WITH CONTINUED SYNOPTIC SCALE LIFT AND WEAK LOW LEVEL
SOUTHEASTERLY JET OVERNIGHT...WILL KEEP A CHANCE OF STORMS IN THE
FORECAST THROUGH TONIGHT.
.LONG TERM...EASTERLY UPSLOPE SURFACE FLOW WILL MOVE OVER THE
PLAINS FROM A SHORTWAVE TROUGH DIVING SOUTH FROM THE DAKOTAS
ALOFT. COMBINE THIS WITH A FEW DISTURBANCES MOVING IN THE
WESTERLY FLOW ALOFT AND INCREASING UPPER AND MID-LEVEL MOISTURE
MOVING IN FROM THE SOUTHWEST WILL ALL COME TOGETHER TUESDAY AND
WEDNESDAY FOR COOLER AND WETTER DAYS. THE FOCUS FOR THE MOST
SIGNIFICANT WEATHER WILL BE EAST OF THE MOUNTAINS AS SLIGHTLY
DRIER AIR WILL BE FILTERING IN FROM THE WEST. STORM MOTIONS ARE
PROGGED TO BE SLOW...10 MPH OR LESS SO THUNDERSTORMS WITH HEAVY
RAINFALL WILL BE A CONCERN. BEST INSTABILITY WILL BE OUT TOWARDS
THE EASTERN STATE BORDER WITH HAIL AND STRONG WINDS THE THREAT.
ALL THE CONDITIONS WILL EXIST THROUGH THE BOTH DAYS TO HAVE AT
LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS LAST THROUGHOUT
THE NIGHTS. TEMPERATURES WILL BE AS MUCH AS 10 DEGREES COOLER THAN
TODAY WITH READINGS IN THE UPPER 70S TO LOWER 80S FOR THE PLAINS
AND 60S TO 70S FOR THE HIGH COUNTRY.
BEGINNING THURSDAY...THE FLATTENED UPPER RIDGE WILL BEGIN BUILDING
BACK NORTH THROUGH FRIDAY...STRETCHING FROM ARIZONA UP TO
MONTANA. THIS WILL PUT COLORADO UNDER NORTH-NORTHWEST FLOW ALOFT.
THE SHORTWAVE TROUGH MAY STILL HAVE AN AFFECT THURSDAY AND SOUTH
TO SOUTHEASTERLY SURFACE FLOW OVER THE FAR EASTERN PLAINS WILL
TRANSPORT SOME MOISTURE IN FOR SCATTERED STORM ACTIVITY OVER THE
MOUNTAINS AND A SLIGHT CHANCE FOR THE PLAINS. DRIER AIR WILL BE
SPREADING IN FROM THE WEST FRIDAY TO KEEP CHANCES FOR STORMS OVER
THE HIGH TERRAIN WITH ISOLATED COVERAGE. TEMPERATURES WILL BE
CLIMBING BACK TO AVERAGE AND POSSIBLY SLIGHTLY WARMER UNDER THE
BUILDING RIDGE.
ON SATURDAY...A TROUGH WILL MOVE ONSHORE OVER THE WEST COAST AND
START MOVING EAST. SATURDAY WILL BE ONE MORE WARM AND DRY DAY
BEFORE THE TROUGH DRAWS MOISTURE INTO THE AREA FOR SLIGHTLY WETTER
CONDITIONS SUNDAY. WILL HAVE TO FOLLOW THE PROGRESSION OF THE
MODELS FOR THIS TROUGH TO SEE HOW STRONG IT MAY BE. FOR NOW KEPT
TEMPERATURES THE SAME...BUT MAY NEED TO COOL THEM OR LATER
PERIODS.
&&
.AVIATION...WEAK SURFACE BOUNDARY THAT BARELY PUSHED THROUGH THE
FRONT RANGE AIRPORTS WILL KEEP LIGHT AND VARIABLE WINDS IN THE
FORECAST THROUGH 15Z-17Z. ONLY A SLIGHT CHANCE OF LIGHT/PATCHY
FOG DEVELOPING 12Z-14Z WITH MARGINAL T/TD SPREADS. THEN NORMAL
DIURNAL EASTERLIES WILL DEVELOP. STORM CHANCES WILL BE A LITTLE
HIGHER THAN YESTERDAY SO TEMPO VRB20G30-35KT WINDS AND TS OR -TSRA
WOULD BE WARRANTED IN THE FAVORED TIME FRAME FROM 20Z- 02Z. A
SLIGHT CHANCE OF STORMS LINGERING PAST 06Z. BRIEF MVFR CONDITIONS
WOULD BE POSSIBLE IF A STORM CORE PASSES OVERHEAD.
&&
.HYDROLOGY...PRECIPITABLE WATER VALUES AND TEMP PROFILES ARE
SIMILAR TO THOSE OBSERVED YESTERDAY...ALTHOUGH STORM MOTION WILL
LIKELY BE UNDER 10 MPH. STORMS THIS AFTERNOON AND EVENING WILL BE
CAPABLE OF PRODUCING 0.50 TO 1.0 INCH IN 30 MINUTES. THAT WOULD
POSE A RISK OF SOME FLOODING IF ONE OF THESE STRONGER STORMS MOVES
OVER A FOOTHILL BURN SCAR. THE STRONGEST STORMS ON THE PLAINS
COULD PRODUCE 1-2 INCHES IN AN HOUR WITH MINOR FLOODING. THREATS
ARE LOW ENOUGH AT THIS TIME TO PRECLUDE A FLASH FLOOD WATCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....KRIEDERMAN
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
352 AM MDT MON AUG 12 2013
.SHORT TERM...WATER VAPOR LOOP INDICATED A MOISTURE PLUME SHIFTING
NORTHEAST ACROSS COLORADO EARLY THIS MORNING. AT THE SURFACE...A
WEAK SURGE HAD PUSH ACROSS MOST OF THE PLAINS WITH A SLIGHT
INCREASE IN LOW LEVEL MOISTURE. HOWEVER...THIS MOISTURE WAS QUITE
SHALLOW AS PRECIPITABLE WATER VALUES HAD BARELY BUDGED OVER THE
LAST 24 HOURS. OVERALL...THE WEATHER PATTERN REMAINS QUITE SIMILAR
TO YESTERDAY WITH THE UPPER LEVEL RIDGE CENTERED OVER THE STATE.
HOWEVER...ONE FEATURE THAT MAY COME INTO PLAY IS AN UPPER LEVEL
SPEED MAX MOVING ACROSS THE DESERT SOUTHWEST. THE FORECAST AREA
WILL BE IN THE LEFT EXIT REGION OF THIS JET FROM THIS AFTERNOON
THROUGH TONIGHT. THERE WAS DEEP...PERSISTENT...BUT WEAK Q-G LIFT
NOTED IN MOST MODELS THROUGH TONIGHT. THIS SHOULD HELP INCREASE
CONVECTIVE COVERAGE A BIT FROM YESTERDAY. MEANWHILE...SHORT RANGE
MESOSCALE MODELS INCLUDING THE WRF AND HRRR SHOW THE TYPICAL START
TO CONVECTION ALONG THE FRONT RANGE MOUNTAINS AND FOOTHILLS BY
17Z-18Z...AND THEN SPREADING/DEVELOPING EASTWARD THROUGH THE
AFTERNOON HOURS. AT THIS POINT...SEE LITTLE REASON TO ARGUE WITH
THIS SCENARIO. THERE WILL BE A SLIGHT RISK OF ONE OR TWO STORMS
BRIEFLY REACHING SEVERE CRITERIA ON THE PLAINS WITH MARGINAL
HAIL/WIND.
WITH CONTINUED SYNOPTIC SCALE LIFT AND WEAK LOW LEVEL
SOUTHEASTERLY JET OVERNIGHT...WILL KEEP A CHANCE OF STORMS IN THE
FORECAST THROUGH TONIGHT.
.LONG TERM...EASTERLY UPSLOPE SURFACE FLOW WILL MOVE OVER THE
PLAINS FROM A SHORTWAVE TROUGH DIVING SOUTH FROM THE DAKOTAS
ALOFT. COMBINE THIS WITH A FEW DISTURBANCES MOVING IN THE
WESTERLY FLOW ALOFT AND INCREASING UPPER AND MID-LEVEL MOISTURE
MOVING IN FROM THE SOUTHWEST WILL ALL COME TOGETHER TUESDAY AND
WEDNESDAY FOR COOLER AND WETTER DAYS. THE FOCUS FOR THE MOST
SIGNIFICANT WEATHER WILL BE EAST OF THE MOUNTAINS AS SLIGHTLY
DRIER AIR WILL BE FILTERING IN FROM THE WEST. STORM MOTIONS ARE
PROGGED TO BE SLOW...10 MPH OR LESS SO THUNDERSTORMS WITH HEAVY
RAINFALL WILL BE A CONCERN. BEST INSTABILITY WILL BE OUT TOWARDS
THE EASTERN STATE BORDER WITH HAIL AND STRONG WINDS THE THREAT.
ALL THE CONDITIONS WILL EXIST THROUGH THE BOTH DAYS TO HAVE AT
LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS LAST THROUGHOUT
THE NIGHTS. TEMPERATURES WILL BE AS MUCH AS 10 DEGREES COOLER THAN
TODAY WITH READINGS IN THE UPPER 70S TO LOWER 80S FOR THE PLAINS
AND 60S TO 70S FOR THE HIGH COUNTRY.
BEGINNING THURSDAY...THE FLATTENED UPPER RIDGE WILL BEGIN BUILDING
BACK NORTH THROUGH FRIDAY...STRETCHING FROM ARIZONA UP TO
MONTANA. THIS WILL PUT COLORADO UNDER NORTH-NORTHWEST FLOW ALOFT.
THE SHORTWAVE TROUGH MAY STILL HAVE AN AFFECT THURSDAY AND SOUTH
TO SOUTHEASTERLY SURFACE FLOW OVER THE FAR EASTERN PLAINS WILL
TRANSPORT SOME MOISTURE IN FOR SCATTERED STORM ACTIVITY OVER THE
MOUNTAINS AND A SLIGHT CHANCE FOR THE PLAINS. DRIER AIR WILL BE
SPREADING IN FROM THE WEST FRIDAY TO KEEP CHANCES FOR STORMS OVER
THE HIGH TERRAIN WITH ISOLATED COVERAGE. TEMPERATURES WILL BE
CLIMBING BACK TO AVERAGE AND POSSIBLY SLIGHTLY WARMER UNDER THE
BUILDING RIDGE.
ON SATURDAY...A TROUGH WILL MOVE ONSHORE OVER THE WEST COAST AND
START MOVING EAST. SATURDAY WILL BE ONE MORE WARM AND DRY DAY
BEFORE THE TROUGH DRAWS MOISTURE INTO THE AREA FOR SLIGHTLY WETTER
CONDITIONS SUNDAY. WILL HAVE TO FOLLOW THE PROGRESSION OF THE
MODELS FOR THIS TROUGH TO SEE HOW STRONG IT MAY BE. FOR NOW KEPT
TEMPERATURES THE SAME...BUT MAY NEED TO COOL THEM OR LATER
PERIODS.
&&
.AVIATION...WEAK SURFACE BOUNDARY THAT BARELY PUSHED THROUGH THE
FRONT RANGE AIRPORTS WILL KEEP LIGHT AND VARIABLE WINDS IN THE
FORECAST THROUGH 15Z-17Z. THEN NORMAL DIURNAL EASTERLIES WILL
DEVELOP. STORM CHANCES WILL BE A LITTLE HIGHER THAN YESTERDAY SO
TEMPO VRB20G30-35KT WINDS AND TS OR -TSRA WOULD BE WARRANTED IN
THE FAVORED TIME FRAME FROM 20Z-02Z. A SLIGHT CHANCE OF STORMS
LINGERING PAST 06Z. BRIEF MVFR CONDITIONS WOULD BE POSSIBLE IF A
STORM CORE PASSES OVERHEAD.
&&
.HYDROLOGY...PRECIPITABLE WATER VALUES AND TEMP PROFILES ARE
SIMILAR TO THOSE OBSERVED YESTERDAY...ALTHOUGH STORM MOTION WILL
LIKELY BE UNDER 10 MPH. STORMS THIS AFTERNOON AND EVENING WILL BE
CAPABLE OF PRODUCING 0.50 TO 1.0 INCH IN 30 MINUTES. THAT WOULD
POSE A RISK OF SOME FLOODING IF ONE OF THESE STRONGER STORMS MOVES
OVER A FOOTHILL BURN SCAR. THE STRONGEST STORMS ON THE PLAINS
COULD PRODUCE 1-2 INCHES IN AN HOUR WITH MINOR FLOODING. THREATS
ARE LOW ENOUGH AT THIS TIME TO PRECLUDE A FLASH FLOOD WATCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....KRIEDERMAN
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
329 AM EDT Mon Aug 12 2013
.NEAR TERM [Today and Tonight]...
With a firmly established upper level ridge in place for one more
day and PWATS expected to continue to drop as deep layer drier air
advects in from the east, conditions appear favorable for what
should be the hottest day of the summer season thus far! For
example, we are forecasting a High temp of 101 at VLD today (which
would eclipse the earlier 100 from June 12), 99 at TLH (which would
exceed the 98 on June 12 and 13, and a 99 at ABY (which would be a
whopping 4 degrees higher than the 95 which also occurred on June 12
and 13). For reference, it does NOT appear (at this time) that we
will break any record high temps today at these sites which are
listed as follows:
TLH: 100 set in 2011
ABY: 100 set in 1957
VLD: 101 would tie the 101 from the xmACIS database (year unknown)
Despite the very hot temps, we do expect dewpoints to mix out into
the upper 60s to lower 70s, which should keep Heat Indices just
below Heat Advisory Levels (108-113). The lone exception could be
around VLD and the Suwannee River Valley where a VERY few 108s and
109s could be possible. However, this area appears too small to
warrant an Advisory at this time, so will leave it out for now, and
let the day shift make any adjustments if needed. PoPs should be
quite low, generally in the 15-20% range, with only a few 30s
possible across parts of SE AL. This will also set the stage for a
very warm and humid night across the CWA tonight, with lows
generally in the mid to upper 70s from the interior to near the
coast.
&&
.SHORT TERM [Tuesday through Wednesday]...
GOES Blended TPW product and objective precipitable water analysis
from the RAP model shows a plume of above normal PWATs (2.1-2.2")
situated just to the west of our area over the Lower Mississippi
River Valley. This deeper moisture is expected to advect into our
area in the next 24 hours as the upper level ridge centered over
north Florida weakens. At the same time, we will see a weak front
approach from the north, and a weakness (or low-amplitude trough)
develop in the upper level ridge just west of our forecast area.
These ingredients suggest that rain will be on the increase
Tuesday and Wednesday - probably focused in the northwest half of
our area on Tuesday, and then spreading further into our area on
Wednesday. The high PWATs will be accompanied by very weak flow,
with projected storm motions at or below 5 knots (per NAM/GFS).
At least localized heavy rainfall is likely when you juxtapose
deep moisture and very slow storm motions. Therefore, we added
heavy rainfall wording to the forecast on Tuesday and Wednesday in
areas that have "likely" PoPs (>55%). For high temperatures we
kept a NW-SE gradient with the warmest conditions in the SE part
of our area. Low temperatures were kept fairly warm as there
should be an increase in cloud cover.
&&
.LONG TERM [Wednesday Night through Sunday]...
Not much change with the forecast pattern for later this week into
next weekend, as broad low amplitude trough becomes established
over the central Gulf Coast/southeast states. An attendant surface
front will likewise slide swd into the region. Combination of
these features suggests return to wetter than normal pattern,
which will also likely cap high temperatures a bit below normal
each day. We could see some heavy rainfall at times, with WPC
painting 3-3.5" totals on average over the tri-state region.
&&
.AVIATION [through 12 UTC Tuesday]...
Expect VFR conditions to prevail through the period with just few
to sct CU and CI the rest of the overnight hours and during the
day today. Although an isolated TSTM cannot be ruled out, the
minimal PoPs and coverage should preclude any mention of
convection at this time.
&&
.MARINE...
A relatively weak pressure pattern should persist despite the
approach of a weak front from the north. This should keep winds
around 10 knots or less, with seas 2 feet or less. Thunderstorm
activity over the waters should increase by Wednesday.
&&
.FIRE WEATHER...
Red flag conditions are not expected over the next several days,
although today will feature some of the lower RHs in many days.
&&
.HYDROLOGY...
Area river levels continue to slowly decrease or remain steady and
this should be the story of the next couple days. As a rainy
pattern re-emerges by mid-week, we should start to see flows on at
least a few of the rivers begin to increase again by late week or
into the weekend. It is too early to say which rivers may be
affected, as heavy rainfall could be somewhat localized.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 99 74 95 74 91 / 20 10 40 20 60
Panama City 93 79 90 78 88 / 20 20 40 20 50
Dothan 97 75 91 73 88 / 20 20 70 30 70
Albany 99 75 93 74 90 / 20 20 60 30 70
Valdosta 101 72 96 73 93 / 20 10 30 20 60
Cross City 97 72 94 74 93 / 10 10 20 10 30
Apalachicola 91 78 90 78 88 / 10 10 20 20 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Gould
SHORT TERM...Lamers
LONG TERM...Evans
AVIATION...Gould
MARINE...Lamers
FIRE WEATHER...Gould
HYDROLOGY...Lamers
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
155 AM EDT MON AUG 12 2013
.PREV DISCUSSION... /ISSUED 731 PM EDT SUN AUG 11 2013/
UPDATE...
HIGH PRESSURE IS SITUATED ACROSS THE FLORIDA PANHANDLE THIS
EVENING. A LEE TROUGH IS DEVELOPED ALONG THE TAIL END OF THE
APPALACHIANS. CONVECTION REMAINS ACROSS THE NORTHERN CWFA THIS
EVENING. ADDITIONAL ACTIVITY HAS FORMED ACROSS CENTRAL/SOUTHERN TN
ALONG AN OLD OUTFLOW BOUNDARY.
LATEST RUNS OF THE HRRR SHOW THE ACTIVITY OVER TN DIMINISHING WITH
THE LOSS OF HEATING. IN ADDITION...THE STORMS OVER NORTHERN GA
SHOULD BEGIN TO DIMINISH WITH SUNSET. HAVE RE-ADJUSTED POPS TO
REFLECT THE LATEST TRENDS. ALSO MADE SOME TWEAKS TO THE HOURLY
TEMP/DEW GRIDS.
NLISTEMAA
PREV DISCUSSION... /ISSUED 350 PM EDT SUN AUG 11 2013/
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
SHORT RANGE MODELS SHOW LITTLE CHANGE IN THE OVERALL PATTERN THROUGH
THE SHORT TERM... WITH AN ACTIVE WESTERLY FLOW ALOFT PERSISTING.
THIS WILL HELP HOLD A WEAK FRONTAL BOUNDARY NORTH OF THE STATE AND
ACROSS THE TN VALLEY... ALL SUGGESTING THE GREATEST RAIN CHANCES
WILL REMAIN ACROSS NORTH GA AND AREAS NORTHWARD THIS AFTERNOON...
EVENING AND AGAIN ON MONDAY.
REGIONAL RADARS SHOW SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
ONGOING ACROSS FAR NORTH GA THIS AFTERNOON... AND THIS ACTIVITY WILL
PERSIST THROUGH MID EVENING BEFORE DISSIPATING WITH LOSS OF DAYTIME
HEATING. REDEVELOPMENT ALONG OUTFLOWS COULD ALLOW A FEW STORMS TO
PUSH DOWN INTO THE ATLANTA METRO AREA LATER THIS AFTERNOON OR
EVENING... BUT OVERALL TRENDS SUGGEST MOST CONVECTIVE ACTIVITY WILL
REMAIN JUST NORTH OF ATLANTA THROUGH THE EVENING. THIS COULD CHANGE
SLIGHTLY ON MONDAY AS INCREASING UPPER SUPPORT SHOULD HELP SPREAD
CONVECTION FURTHER SOUTH MONDAY AFTERNOON/EVENING. WILL CONTINUE TO
SHOW THE GREATER RAIN CHANCES ACROSS NORTH GA ON MONDAY... BUT AMPLE
MOISTURE /1.8+PW`S/ AND MODERATE INSTABILITIES /2500-3000 CAPE/ WITH
GREATER UPPER SUPPORT SUGGEST SCATTERED STORMS COULD DEVELOP JUST
ABOUT ANYWHERE MONDAY AFTERNOON. ALTHOUGH CANNOT RULE OUT AN
ISOLATED PULSE SEVERE STORM DURING MAX HEATING EACH DAY... THE MAIN
STORM THREAT CONTINUES TO BE LOCALLY HEAVY RAIN AND BRIEF FLOODING
AS STORMS WILL BE SLOW MOVING WITH A TENDENCY TO TRAIN FROM WEST TO
EAST ACROSS THE SAME AREAS. WIDESPREAD RAINFALL TOTALS FROM THIS
AFTERNOON THROUGH MONDAY AFTERNOON SHOULD BE GENERALLY AN INCH OR
LESS ACROSS NORTH GA...WITH SOME ISOLATED HIGHER AMOUNTS OF 2-3
INCHES LIKELY. EXPECT GENERALLY A QUARTER INCH OR LESS ELSEWHERE.
AS FOR TEMPS... LEANED TOWARD A BLEND BETWEEN PERSISTENCE AND THE
SLIGHTLY WARMER MAV THROUGH THE SHORT TERM.
39
LONG TERM /TUESDAY THROUGH SUNDAY/...
LITTLE CHANGE IN LONG TERM PATTERN. ZONAL FLOW CONTINUES INTO THE
BEGINNING OF THE EXTENDED FORECAST BUT GRADUALLY TRANSITIONS TO AN
UPPER TROUGH BY WED/THU. THE CWA REMAINS IN A MOIST AIR MASS WITH
WEAK IMPULSES IN THE UPPER FLOW. MODELS PERSISTENT IN SHOWING
A LITTLE DRIER AIR PUSHING INTO NORTH GA TOWARD THE END OF THE
WEEK WITH A WEDGE LIKE PATTERN SETTING UP. THIS WILL DEPEND UPON HOW
FAR SOUTH THE SURFACE BOUNDARY SINKS THOROUGH THE STATE. WILL CONTINUE
WITH PERSISTENCE AND KEEP POPS MENTIONED THROUGH DAY 7...WITH SOME
LOWERING OF POPS ACROSS THE NORTH BY THE END OF THE FORECAST. IF
SURFACE BOUNDARY PUSHES INTO CENTRAL GA AND THE EASTERLY FLOW SETS
UP...TEMPERATURES BY LATE WEEK SHOULD BE SEVERAL DEGREES COOLER
THAN SEASONAL NORMS.
01
&&
.AVIATION...
06Z UPDATE...
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. DIURNAL CONVECTION
EXPECTED AGAIN THIS AFTERNOON AND EARLY EVENING. WINDS WILL REMAIN
WESTERLY...GENERALLY 5-8KT THROUGH THE DAY...AND LESS THAN 5 KT OVERNIGHT.
//ATL CONFIDENCE...06Z UPDATE...
HIGH CONFIDENCE ON ALL ELEMENTS.
31
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 90 72 89 70 / 50 30 60 30
ATLANTA 88 72 87 71 / 50 30 60 30
BLAIRSVILLE 83 68 81 64 / 60 50 60 30
CARTERSVILLE 87 70 86 69 / 60 40 60 30
COLUMBUS 92 74 91 73 / 40 30 60 30
GAINESVILLE 87 71 85 70 / 50 40 60 30
MACON 93 71 91 71 / 40 30 50 30
ROME 88 71 88 69 / 70 50 60 30
PEACHTREE CITY 88 70 87 70 / 50 30 60 30
VIDALIA 95 75 93 73 / 30 20 40 30
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...31
LONG TERM....16
AVIATION...31
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
109 AM CDT MON AUG 12 2013
.DISCUSSION...
837 PM CDT
SHOWERS WHICH HAVE PERSISTED NEAR THE I-88/I-90 CORRIDORS FOR MUCH
OF THE EVENING HAVE BEGUN TO SHOW A WEAKENING TREND...AND SHOULD
CONTINUE TO DISSIPATE AS THE SURFACE COOLS AND WHAT MEAGER
INSTABILITY THAT WAS THERE WEAKENS. THIS WILL ALLOW FOR A SHORT
BREAK IN PRECIPITATION TONIGHT BEFORE STRONGER SHOWERS AND
THUNDERSTORMS ARRIVE LATER. NO MAJOR CHANGES IN THINKING FOR THE
OVERNIGHT HOURS AS AN AREA OF THUNDERSTORMS CURRENTLY OVER IOWA IS
EXPECTED TO CONTINUE TO DEVELOP EASTWARD. THUNDERSTORMS SHOULD
MOVE OVER MAINLY THE NORTHERN TIER OR TWO OF COUNTIES ON THE NOSE
OF A VERY MODEST 25-30KT LOW/MID LEVEL WIND MAX THAT WILL INCREASE
MOISTURE CONVERGENCE WITHIN A NARROW CORRIDOR OF MUCAPE OF AROUND
700 J/KG. IT APPEARS THE BEST TIMING WILL BE FOR STORMS TO
INCREASE IN COVERAGE OVER THE WESTERN CWA AROUND OR JUST BEFORE
MIDNIGHT TONIGHT...THEN THE HEAVIEST PRECIP SHOULD BEGIN TO SHIFT
EAST OF THE CWA IN THE PREDAWN HOURS MONDAY.
DEUBELBEISS
//PREV DISCUSSION...
310 PM CDT
MAIN FORECAST CONCERNS FOCUS ON SHOWER/THUNDERSTORM POTENTIAL
THROUGH THE FIRST 24-36 HOURS OF THE PACKAGE...WITH THE APPROACH AND
PASSAGE OF SLOW MOVING COLD FRONT AND WEAK FRONTAL WAVE TONIGHT
THROUGH MONDAY. SURFACE HIGH PRESSURE WILL THEN SPREAD ACROSS THE
REGION MID-LATE WEEK...MAKING FOR A RELATIVELY QUIET PERIOD OF
AUGUST WEATHER...WITH TEMPERATURES AVERAGING COOLER THAN NORMAL.
THE MAIN FEATURES ON THE LOCAL WEATHER MAP THIS AFTERNOON CONSIST OF
AN AREA OF HIGH PRESSURE OVER CENTRAL ILLINOIS...WHICH CONTINUES TO
WEAKEN AND DRIFT SOUTHEAST OF THE LOCAL CWA. OF MORE INTEREST IS A
WEST-EAST SURFACE FRONTAL BOUNDARY...WHICH STRETCHES FROM THE HIGH
PLAINS OF EASTERN WYOMING...ACROSS NEBRASKA AND NORTHERN IOWA INTO
FAR NORTHWEST ILLINOIS PER 19Z ANALYSIS. WEAKENING AREAS OF
PRECIPITATION HAVE CONTINUED TO WORK EAST ACROSS SOUTHERN
MN/NORTHERN IA AND SOUTHERN WI DURING THE DAY...IN RESPONSE TO WEAK
BUT PERSISTENT WEST-SOUTHWEST LOW LEVEL FLOW INDUCED BY SHORT WAVE
PROPAGATING ACROSS THE UPPER MISSISSIPPI VALLEY...AND ASSOCIATED
WARM/MOIST ADVECTION ACROSS THE LOW LEVEL BAROCLINIC ZONE. WHILE
PRECIP IN THE WFO LOT CWA HAS BEEN LIMITED TO MAINLY A FEW SPRINKLES
ALONG THE IL/WI BORDER...SPC RAP MESOANALYSIS AND RAP/WRF FORECAST
SOUNDINGS CONTINUE TO DEPICT SOME WEAK INSTABILITY DEVELOPING OVER
NORTHWEST/NORTH CENTRAL IL NEAR THE SURFACE FRONT DURING THE LATE
AFTERNOON HOURS. 250-500 J/KG MUCAPE ADMITTEDLY WEAK...THOUGH
PRESENCE OF PERSISTENT WEAK CONVERGENCE/ASCENT ALONG THE BAROCLINIC
BOUNDARY DOES PRESENT SOME POTENTIAL FOR ADDITIONAL SHRA/ISOLATED
TSRA DEVELOPMENT...WITH SOME INCREASE IN CU DEVELOPMENT NOTED IN
RECENT GOES VIS IMAGERY. HAVE MAINTAINED AN ISOLATES SHRA/TSRA
MENTION AFTER 4-5 PM ACROSS PARTS OF NORTH CENTRAL ILLINOIS ROUGHLY
NORTH OF THE ROCK AND WEST OF THE FOX RIVERS.
THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THEN APPEARS TO INCREASE
FROM MID/LATE-EVENING INTO THE OVERNIGHT HOURS FROM NORTHEAST IOWA
INTO SOUTHERN WISCONSIN...AND ADJACENT PORTIONS OF NORTHERN
ILLINOIS. THIS INCREASE IS IN RESPONSE TO WEAK LARGE SCALE HEIGHT
FALLS INDICATIVE OF ASCENT WITH ADDITIONAL SHORT WAVE ENERGY
APPROACHING FROM UPSTREAM...AND INCREASING MOISTURE TRANSPORT ALONG
LOW LEVEL BAROCLINIC ZONE WITH 925-850MB WEST-SOUTHWEST 20-25 KT
FLOW AS INDICATED BY COMPLEMENTARY RAP/WRF-NAM PROGS. UPPER LEVEL
DIVERGENCE IN RIGHT ENTRANCE REGION TO UPPER LEVEL JET STREAK MAY
ALSO AID IN DEVELOPMENT FROM NORTHEAST IA INTO SOUTHWEST WI EARLIER
IN THE NIGHT...BEFORE IT TRANSLATES FARTHER EAST ACROSS MICHIGAN
LATE. WEAK SURFACE WAVE ALONG FRONT CURRENTLY OVER NORTHEAST
NEBRASKA IS PROGGED TO MOVE ACROSS SOUTHERN WI IN THE PROCESS.
WITH THE LOW LEVEL JET GRADUALLY VEERING FROM WEST-SOUTHWEST TO WEST
THROUGH THE NIGHT...THIS SHOULD HELP FOCUS FOR PRECIP SHIFT FROM
NORTHEAST IA/SOUTHWEST WI EARLY...TO SOUTHWESTERN MICHIGAN BY
SUNRISE. ALL GUIDANCE POINTS TO A FAIRLY LIMITED PORTION OF NORTHERN
IL BEING AFFECTED...PRIMARILY NORTH OF THE INTERSTATE 88 CORRIDOR.
WHILE INSTABILITY IS NOT PARTICULARLY IMPRESSIVE...UPSTREAM PWAT
VALUES ARE ROUGHLY 1.25-1.50 INCHES AND WESTERLY LOW LEVEL FLOW
MAY SUPPORT SLOW EASTWARD TRANSLATION OF RESULTING CELLS. THIS COULD
PRODUCE SOME LOCALLY HEAVY RAINFALL IF TRAINING WERE TO OCCUR.
THE TRAILING COLD FRONT IT THEN PROGGED TO PUSH SLOWLY SOUTHEAST
ACROSS THE FORECAST AREA ON MONDAY...AS THE WEAK LOW PULLS AWAY
ACROSS LOWER MICHIGAN AND DEEPER FLOW OVER THE UPPER MIDWEST BECOMES
NORTHWESTERLY WITH DIGGING UPPER TROUGH. ADDITIONAL SCATTERED SHOWER
AND THUNDERSTORM DEVELOPMENT IS POSSIBLE ALONG/AHEAD OF THE FRONT...
WITH THE GREATEST POTENTIAL ACROSS THE SOUTHEAST HALF OF THE CWA
WHERE THE FRONT WILL BE DURING THE BETTER DIURNAL INSTABILITY.
INCREASE IN MID-LEVEL FLOW ACROSS THE REGION ON MONDAY WILL LIKELY
SUPPORT A GREATER CONDITIONAL MARGINAL SEVERE WIND/HAIL THREAT
ACROSS THE SOUTHEAST COUNTIES AND AREAS EAST BY AFTERNOON.
UPPER TROUGH CONTINUES TO DIG ACROSS THE NORTHEAST CONUS INTO MONDAY
NIGHT...WITH A SECONDARY PUSH OF COOLER DRIER AIR FROM THE NORTH
HELPING TO SHOVE THE COLD FRONT OUT OF THE CWA OVERNIGHT...AND COOL
HIGH PRESSURE BUILDING SOUTHEAST ACROSS THE AREA TUESDAY-WEDNESDAY.
WITH THE MAIN UPPER TROUGH AXIS REMAINING OFF TO THE EAST OF THE
AREA...AND UPPER RIDGE TO THE WEST ACROSS ROCKIES...A PERIOD OF
FAIRLY QUIET AND COOLER THAN AVERAGE WEATHER IS ANTICIPATED. LOW
LEVEL THERMAL GUIDANCE SUGGESTS AFTERNOON HIGHS IN THE MID-UPPER 70S
DURING THE MID-WEEK PERIOD...GRADUALLY MODERATING TO THE UPPER 70S
AND LOWER 80S LATE WEEK AND NEXT WEEKEND. SOME INDICATION IN THE
LONGER RANGE GUIDANCE THAT AN UPPER LOW WILL DEVELOP ACROSS THE
LOWER OHIO OR TENNESSEE VALLEYS LATE IN THE WEEKEND...WITH BOTH THE
ECMWF AND GFS RUNS SUGGESTING THE POTENTIAL TO WRAP A LITTLE
MOISTURE INTO THE AREA FROM THE SOUTHEAST. OTHERWISE...APPEARS
MAINLY DRY THROUGH THE PERIOD BEYOND TOMORROW.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* SHRA AND TSRA OVERNIGHT INTO EARLY THIS MORNING.
* SHRA AND TSRA POTENTIAL EARLY THIS AFTERNOON.
* TIMING OF COLD FRONT PASSAGE AND SUBSEQUENT FLIP FROM NORTH-
NORTHWEST TO NORTHEAST WINDS.
RC
//DISCUSSION...UPDATED 06Z...
TRICKY CONVECTIVE FORECAST THROUGH MONDAY AFTERNOON. THOUGH IT
REMAINS POSSIBLE FOR SHRA AND TSRA DRIVEN BY INCREASING LOW LEVEL
WINDS OVER IA AND WI TO REMAIN NORTH OF THE TERMINALS THROUGH THE
EARLY MORNING BEFORE SHIFTING EAST...FAVOR THE IDEA OF A GRADUAL
SINKING SOUTH AND A WINDOW FOR OCCASIONAL SHOWERS AT
RFD/DPA/ORD/MDW. IF SHRA DIRECTLY IMPACT THE TERMINALS...COULD SEE
PERIODIC MVFR VSBY BUT CIGS SHOULD REMAIN VFR. CONFIDENCE IS LOW
ON TSRA DIRECTLY IMPACTING THE TERMINALS BUT THERE WILL BE ENOUGH
ELEVATED INSTABILITY TO WARRANT VCTS MENTION.
A COLD FRONT CURRENTLY STRETCHING FROM NEAR LAKE SUPERIOR TO KMSP
WILL SAG SOUTH AND REACH THE TERMINALS DURING THE
AFTERNOON...TURNING WINDS FROM WEST-SOUTHWEST TO NORTH-NORTHWEST.
AHEAD OF THE FRONT...IN THE EARLY TO MID MORNING...INSTABILITY
SHOULD WANE ENOUGH TO PRECLUDE MUCH THUNDER IN ANY ONGOING SHRA
ACTIVITY. HOWEVER ENOUGH INSTABILITY COULD BUILD IN THE LATE
MORNING INTO EARLY AFTERNOON FOR A FEW HR WINDOW FOR DPA/ORD/MDW
AND GYY TO SEE TSRA IN THE AREA BEFORE THE FRONTAL PASSAGE. IT
APPEARS THAT GYY WOULD HAVE THE BEST CHANCE TO SEE A PERIOD OF
TSRA AT THE AIRPORT...SO MAY HAVE TO ADD A TEMPO THERE ON THE NEXT
UPDATE. THERE REMAINS SOME UNCERTAINTY ON EXACT TIMING OF FRONTAL
PASSAGE...BUT ONCE IT DOES OCCUR IN THE EARLY TO MID
AFTERNOON...ORD/MDW AND GYY ARE EXPECTED TO FLIP FROM NORTH-
NORTHWEST WINDS TO NORTHEAST FAIRLY QUICKLY. WITH COOLER AIR
COMING IN BEHIND THE FRONT AND INSTABILITY EXPECTED TO ONLY SLOWLY
DIMINISH BEHIND ITS PASSAGE...MAY EVEN NEED TO WATCH FOR SHRA
DEVELOPMENT ON THE LAKE BREEZE FOR THE EASTERN TERMINALS.
RC
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* LOW-MEDIUM CONFIDENCE IN A PERIOD OF SHRA INTO EARLY THIS
MORNING...LOW CONFIDENCE IN TSRA DIRECTLY IMPACTING THE
TERMINALS.
* LOW CONFIDENCE IN TSRA DIRECTLY IMPACTING THE TERMINALS EARLY
THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN TIMING OF FRONTAL PASSAGE AND WIND
SHIFT FROM NORTH-NORTHWEST TO NORTHEAST.
RC
//OUTLOOK FOR ORD/MDW FOR 12Z TUESDAY-12Z SUNDAY...UPDATED 00Z...
TUESDAY THROUGH SATURDAY...VFR. NO SIG WX.
ALLSOPP
&&
.MARINE...
330 PM CDT
AS HIGH PRESSURE CENTERED OVER THE CENTRAL GREAT LAKES SHIFTS
SOUTHEAST TOWARDS THE OHIO VALLEY TONIGHT...A GENERAL SOUTHERLY
DIRECTION CAN BE EXPECTED ACROSS THE LAKE. ALTHOUGH...A WEAK
TROUGH OF LOW PRESSURE WILL MOVE EAST THROUGH ONTARIO AND THE
NORTHERN GREAT LAKES WITH WINDS THEN EXPECTED TO BEGIN SHIFTING TO
THE WEST LATE TONIGHT. AS THIS TROUGH EXITS TO THE EAST AND HIGH
PRESSURE BUILDS SOUTH OUT OF CANADA INTO THE NORTHERN PLAINS
MONDAY AND MONDAY NIGHT...WINDS WILL TURN MORE NORTHERLY ON MONDAY
WHILE INCREASING. NORTHERLY WINDS AND WAVES WILL CONTINUE TO
INCREASE/BUILD MONDAY NIGHT INTO TUESDAY...WITH WAVES HAZARDOUS TO
SMALL CRAFT POSSIBLE ACROSS BOTH THE ILLINOIS AND INDIANA
NEARSHORE WATERS TUESDAY/TUESDAY NIGHT. WINDS AND WAVES WILL BEGIN
TO DIMINISH LATER TUESDAY NIGHT INTO WEDNESDAY...AS HIGH PRESSURE
SETTLES BACK IN.
RODRIGUEZ
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
324 AM CDT MON AUG 12 2013
.SYNOPSIS...
ISSUED AT 319 AM CDT MON AUG 12 2013
06Z SFC ANALYSIS HAS A WEAK LOW WEST OF KMIW WITH A WARM FRONT TO
NEAR KCID. A COLD FRONT RAN FROM THE LOW INTO SOUTHERN NEBRASKA.
ANOTHER WEAK LOW WAS AT KLSE WITH A TROF CONNECTING THAT LOW WITH
THE LOW NEAR KMIW. DEW POINTS WERE IN THE 50S AND 60S ACROSS THE
MIDWEST WITH 70S ACROSS THE DEEP SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 319 AM CDT MON AUG 12 2013
RADAR TRENDS THE PAST SEVERAL HOURS SHOW A SLOW DECAY OF THE
PRECIPITATION ACROSS IOWA/ILLINOIS. THIS MAY BE PARTLY DUE TO THE
MCS MOVING FROM NEBRASKA INTO KANSAS INTERCEPTING THE MOIST FLOW. AT
THE SAME TIME THE OVERALL CONVERGENCE AND MOISTURE TRANSPORT ACROSS
IOWA HAS WEAKENED ALONG THE FRONT.
BASED ON TRENDS FROM THE RAP AND OTHER MODELS...THE MCS...HEAVY RAIN
AND LIFT TOOLS SUGGEST A CONTINUED SLOW DECAY OF THE CONVECTION
ACROSS THE CWFA THROUGH SUNRISE AND THE MORNING COMMUTE. BY MID TO
LATE MORNING AND CONTINUING INTO EARLY AFTERNOON VERY LITTLE IF ANY
CONVECTION WILL BE SEEN DUE TO THE NOCTURNAL CONVECTIVE MINIMA.
DIURNAL CONVECTION WILL DEVELOP DURING THE AFTERNOON AS THE
CONVECTIVE TEMPERATURE IS ACHIEVED. HOWEVER...TRENDS FROM THE RAP
SUGGEST A MAJORITY OF THIS CONVECTION WILL BE GENERALLY SOUTH OF A
KOTM TO KSQI LINE AND REMAIN ISOLATED TO SCATTERED IN NATURE.
IF ANY CONVECTION SPILLS OVER INTO THE EVENING HOURS IT WILL QUICKLY
DISSIPATE WITH THE SETTING SUN. FROM MID EVENING THROUGH SUNRISE
TUESDAY...QUIET AND DRY CONDITIONS WILL BE SEEN AS THE NEXT HIGH
PRESSURE BEGINS BUILDING INTO THE MIDWEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 319 AM CDT MON AUG 12 2013
FLOW PATTERN ALOFT TO REMAIN NORTHWESTERLY AS AREA LOCATED BETWEEN
WESTERN CONUS RIDGE AND EASTERN TROUGH. AT THE SURFACE... LARGE
EXPANSE OF CANADIAN HIGH PRESSURE WILL BUILD INTO THE AREA THROUGH
MID-WEEK... THEN ONLY SLOWLY DRIFT INTO THE GREAT LAKES AND OHIO
VALLEY THIS WEEKEND ALL THE WHILE REMAINING THE DOMINANT WEATHER
FEATURE. THE RESULT WILL BE A PROLONGED STRETCH OF FANTASTIC
WEATHER FOR THE AREA FEATURING COOLER AND DRIER THAN NORMAL
CONDITIONS INTO NEXT WEEKEND. TUE NGT AND WED NGT LOOK TO BE THE
COOLEST OF THE STRETCH... WITH LOWS IN THE 40S LIKELY AT THE
TYPICAL COLD DRAINAGE SITES GIVEN PROGGED 850 MB TEMPS OF 7C TO 9C
AND CALM WINDS. IN ADDITION... SOME PATCHY RADIATIONAL FOG
POSSIBLE LATE TUE/WED NGTS IN THE RIVER VALLEYS AND OTHER LOW
LYING AREAS GIVEN SHALLOW STEEP LOW LEVEL INVERSION. TEMPS OVERALL
THOUGH MAINLY IN THE MID 70S TO LOWER 80S FOR HIGHS TUE-FRI AND
MAINLY IN THE 50S FOR LOWS. HAVE LOWERED MINS MOST PERIODS TUE
NGT-FRI NGT BY 1-2 DEGS BUT MAY NEED TO LOWER FURTHER AS CONTINUED
DRYING SHOULD AID IN EXPANDING DAILY DIURNAL RANGES... WITH LOWS
GENERALLY FAVORING NEAR OR BELOW THE COOL SIDE OF GUIDANCE AND
HIGHS NEAR BLEND OR TOWARD WARMER SIDE OF GUIDANCE. A SLOW WARMING
TREND ONLY TO AROUND NORMAL IS EXPECTED NEXT WEEKEND WITH 850 MB
TEMPS WARMING TO AROUND 12C TO 15C YIELDING HIGHS IN THE 80S.
BUT... EASTERLY SURFACE WINDS SHOULD ENSURE CONTINUED LOW HUMIDITY
LEVELS AND EXTREMELY COMFORTABLE CONDITIONS DESPITE THE MODERATION
IN TEMPS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 319 AM CDT MON AUG 12 2013
MAINLY VFR WX WILL BE SEEN THROUGH 06Z/13 AS A WEAK FRONT MOVES
THROUGH EASTERN IOWA AND ILLINOIS. IF CONVECTION AFFECTS A TAF
SITE...A BRIEF PERIOD OF MVFR CONDITIONS WILL BE POSSIBLE. FOR THE
MOST PART THE PROBABILITY OF A SHRA/TSRA AFFECTING A TAF SITE IS AT
BEST 20 PERCENT WITH KBRL/KMLI HAVING THE BEST CHANCE. AFT 06Z/13
MAINLY VFR WX IS EXPECTED TO CONTINUE. HOWEVER...WITH LIGHT WINDS
AND CLEARING SKIES THE POSSIBILITY DOES EXIST FOR MVFR VSBYS
DEVELOPING DUE TO FOG.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
346 AM CDT Mon Aug 12 2013
...UPDATED SYNOPSIS, SHORT TERM, LONG TERM SECTIONS..
.SYNOPSIS...
ISSUED AT 343 AM CDT MON AUG 12 2013
The hemispheric scale general circulation has not changed much over
the past couple of days as a large Hudson Bay gyre continues to
influence sensible weather across much of eastern Canada and the
adjacent northeastern CONUS. A ridge of high pressure in the
mid-upper troposphere was centered across the Rockies while a
slow-moving upper low was moving north along the Pacific Northwest
coast. RAOB and RAP analysis continued to indicate a strong
subtropical jet at or just south of 30N latitude from well off the
southern California coast into Arizona and northern New Mexico.
Nocturnal water vapor loop shows a substantial mid level drying
signature tied to this jet which is disrupting the monsoonal flow
pattern across the Desert Southwest. On the mesoscale, a weak
shortwave trough moving through the Central Plains spawned the
development of a couple of mesoscale convective systems (MCS)...the
largest being across north-central Kansas. Another smaller MCS was
located across far south-central Kansas. The stronger, northern MCS
had some low level frontogenesis to aid in deeper tropospheric
upward vertical motion.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 343 AM CDT MON AUG 12 2013
The very weak frontal boundary, which promoted the development and
sustainment of the MCS across northern Kansas, will continue its
slow push into southwest Kansas through mid-morning Monday. The
front is difficult to identify on a surface chart with winds up in
Nebraska either calm or some very light variation of east...and the
MSLP gradient is very weak as well. Nevertheless, the MCS and its
outflow boundary (OFB) will provide additional convergence with the
OFB likely bisecting the southwest Kansas region by midday. None of
the convective-allowing models are showing much in the way of
thunderstorm redevelopment back across southwest Kansas this
afternoon where the remnant OFB will have likely stalled out. That
being said, the 00z and now the latest 06z run of the NAM12 do show
a more favorable QPF signal in the low level convergence zone across
southwest Kansas in the 21-00z time frame later on today. I tend to
lean more toward the NAM12 given that the lower troposphere is
fairly moist, there will be boundary layer convergence, and a
capping inversion that is not overly strong. The Storm Prediction
Center slight-risk for severe storms is focused from southwest
Kansas into northeastern Oklahoma and I cannot argue with this
forecast. Should storms form on the old front/OFB as I think they
will, then organized multi-cell or even a supercell storm could
exist given strong upper tropospheric flow (250mb winds of
65-75kts). Large hail to half-dollars and damaging wind gusts to 65
mph seem to be the best prediction for maximum severe threats in
this setup later this afternoon/evening. It is unclear how the heavy
rain threat will play out...as there will likely be another MCS
thriving during the late evening and eventually the overnight
hours...however it is extremely difficult to predict how large of an
MCS there will be and where exactly it will focus on. The most
likely location would be between the Arkansas River and the Oklahoma
border and east of Highway 83. We will not issue any flood/flash
flood headline at this time given too much uncertainty/low
confidence in the risk.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 343 AM CDT MON AUG 12 2013
Tuesday:
Large uncertainty exists Tuesday spatiotemporally with MCS activity.
The ECMWF has been persistent over the last few nights in
advertising a decent convective/QPF signal across SW Kansas. Upslope
flow from the sfc to 850 hPa, along with copious boundary layer
moisture will set the stage for decent precip event across the
region. The GFS/GEM also show MCS activity marching across the
Kansas prairies through the day. The NAM has been consistent in a
much drier solution with little in the way of precipitation. To
further uncertainty, the 4 km nested NAM is in agreement (different
cp schemes) with the operational NAM. The two cores of the WRF are
in between the global and aforementioned mesoscale models. Given the
fact that precipitable water values are forecasted to between the
75th percentile to +2SD, will keep with likely precipitation
probability percentage points. Now is not the time to be
conservative with precipitation chances, since we are dealing with a
moist and unstable atmosphere. Heavy rain will be possible as well.
Went with ECE guidance for temperatures, which shows maximums around
the 80F mark. Minimums for Wednesday morning look to be in the 60sF.
Wednesday:
With northwesterly flow aloft and low level upslope flow continuing
Wednesday, we could see diurnal thunderstorm activity. Will go with
chance precipitation probability percentage points for now with a
bias towards the ECMWF solution. Wednesdays activity should be more
isolated, and the resultant threat for heavy rain will be isolated
as well. Maximums will be pleasant and in the upper 70sF. Lows still
in the 60sF for Thursday morning.
Thursday and beyond:
Will stick with the weighted allblend solution for the rest of the
period as uncertainty continues. The bottom line is that there will
be bouts of convection thru Saturday. The forecast could be dry
Sunday, as a 500 hPa ridge extends eastward with resultant
increasing geopotential heights and a dry northerly flow aloft.
Highs should moderate to near normal by next weekend. With all the
uncertainty in the extended, we`ll tread lightly.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
ISSUED AT 1243 AM CDT MON AUG 12 2013
The overnight thunderstorm activity is expected to remain north
and east of all three TAF sites (DDC, GCK, HYS), so will be
keeping thunderstorms out of the TAF through the night. There will
be a better chance for thunderstorms on Monday afternoon, so will
be carrying a PROB30 group during the afternoon and early evening
hours as a shortwave trough moves across western Kansas and the
surface front moves down into the southwest Kansas region.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 89 67 80 62 / 40 60 60 60
GCK 86 66 79 64 / 50 60 60 60
EHA 89 67 79 61 / 40 50 60 60
LBL 90 68 79 64 / 40 50 60 60
HYS 85 67 79 60 / 30 60 40 40
P28 90 70 82 65 / 40 60 60 60
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...Sugden
AVIATION...UMSCHEID
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
335 AM EDT MON AUG 12 2013
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 330 AM EDT MON AUG 12 2013
06Z SFC ANALYSIS SHOWS THE FRONTAL BOUNDARY NOW LYING WEST TO EAST
THROUGH THE SOUTHERN TIER OF THE CWA. THIS SHOWS UP IN THE LATEST
RADAR DATA...AS WELL...WITH SIGNS OF CONVECTION ALONG IT IN EAST
KENTUCKY AND SHOWERS POPPING NEARBY THROUGH CENTRAL KENTUCKY. NORTH
OF THE BOUNDARY...CIGS HAVE CLEARED OUT AND THIS HAS ALLOWED
WIDESPREAD FOG TO FORM WITH REPORTS OF IT LOCALLY DENSE IN MANY OF
THE VALLEYS NORTH OF JKL. FOR THIS REASON...AND THE EXPECTATION OF AT
LEAST PATCHY DENSE FOG IN THE SOUTHERN VALLEYS BY DAWN...A DENSE FOG
ADVISORY IS IN EFFECT THROUGH EAST KENTUCKY UNTIL 10 AM. JUST A HINT
OF A NORTH TO SOUTH TEMPERATURE AND DEWPOINT GRADIENT EXISTS ACROSS
THE BOUNDARY. T/TD ARE CURRENTLY IN THE UPPER 60S NORTH OF THE
MOUNTAIN PARKWAY...WITH VALUES IN THE LOWER 70S TO THE SOUTH.
THE MODELS ARE IN GOOD AGREEMENT ALOFT...AT LEAST LOCALLY...THROUGH
THE SHORT TERM AS THEY ALL DEPICT A DEEP TROUGH NORTH OF THE GREAT
LAKES AND STOUT RIDGING OVER THE DEEP SOUTH. NEAR ZONAL FLOW ALONG
THE OHIO RIVER WILL BRING SHORTWAVES ALONG WITH IT. A MORE DECENT ONE
WILL BE COMING OUT OF THE HIGH PLAINS AND START TO IMPACT EAST
KENTUCKY LATER TODAY...PASSING THROUGH TONIGHT. THIS WAVE WILL HELP
TO DRAG THE LARGER TROUGH FURTHER SOUTH INTO THE DAY TUESDAY WITH
SOME HEIGHT FALLS BY EVENING. ONCE AGAIN...THE MORE MESOSCALE
DETAILS PRIMARILY WILL GUIDE THE WEATHER THROUGH TUESDAY.
ACCORDINGLY...HAVE LEANED TOWARD THE NAM12 WITH SOME BOLSTERING OF
ITS SOLUTION FROM THE LATEST ECMWF...AND IN THE NEAR TERM...THE
CURRENT HRRR RUN.
SENSIBLE WEATHER WILL FEATURE A FOGGY START TO THE DAY FOR MOST OF
THE AREA. THE FOG WILL BURN OFF BY 10 AM AND THEN EXPECT THE NEXT
ROUND OF SHOWERS AND THUNDERSTORMS TO MOVE INTO THE CWA FROM THE
SOUTHWEST IN CONJUNCTION WITH ANOTHER RIPPLE ALONG THE STALLED
FRONT. THIS ONE WILL HAVE SOME DECENT UPPER LEVEL SUPPORT AND PLENTY
OF MOISTURE ALONG THE FRONT...SO HEAVY RAINFALL WILL REMAIN A THREAT
INTO TUESDAY MORNING...SOMETHING WE WILL HIGHLIGHT IN THE HWO. EXPECT
SOME PATCHY FOG AGAIN TONIGHT AND THEN A NORTH TO SOUTH DIMINISHING
TREND TO THE CONVECTION WITH TIME ON TUESDAY AS THE DEEPER MOISTURE
FROM FRONT STARTS TO MOVE SOUTH. TEMPS WILL BE IN THE LOWER 80S
TODAY AS THE ARRIVING CONVECTION...AND MORNING FOG...LIMIT THE RISE.
THEY LOOK EVEN COOLER TUESDAY WITH THAT FRONT AND ITS SHOWERS/TSTORMS
DROPPING SOUTH...TONIGHT WILL STILL BE RATHER WARM AND MUGGY...
THOUGH.
USED THE CONSSHORT AS A STARTING POINT FOR WINDS AND DEWPOINTS
THROUGH 24 HOURS...THEN CONSALL THEREAFTER. WITH TEMPS...FAVORED
THE CONSALL FOR MAX AND MIN VALUES ALONG WITH ITS DERIVED DIURNAL
CURVE. AS FOR POPS...HAVE ENDED UP CLOSER TO THE VERY WET MET NUMBERS
TODAY AND THEN AT OR SLIGHTLY LOWER THAN A MET/MAV CONSENSUS ON
TUESDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 250 AM EDT MON AUG 12 2013
AN AMPLIFIED 50H PATTERN WITH A RIDGE OVER THE ROCKIES AND A TROF
OVER THE ERN CONUS. AT THE SFC...HIGH PRESSURE OVER THE NRN PLAINS
WILL CONTINUE TO PUSH THE COLD FRONT FURTHER TO THE SOUTH WITH DRIER
AIR INFILTRATING THE COMMONWEALTH. THIS PATTERN WILL LEAD TO A MOSTLY
DRY FCST FOR MUCH OF ERN KY UNTIL THE END OF THE WEEK. BY FRI
MORNING AN INVERTED TROF AT THE SFC WILL ALLOW MOISTURE TO CREEP
INTO THE AREA AND DAY TIME HEATING COULD SPARK A FEW SHOWERS. EVEN
AS THIS IS HAPPENING...AT THE 50H LEVEL A VORT MAX IS DROPPING INTO
THE CNTRL PLAINS TO REINFORCE THE ERN TROF. THIS VORT MAX WILL
DEVELOP OVER THE WEEKEND INTO A CLOSED LOW AS THE SFC HIGH PRESSURE
SLIPS TO NEW ENG AND ALLOWS ADDITIONAL MOISTURE TO INVADE THE REGION
WITH A GOOD CHANCE OF PRECIP.
WITH THE HIGH PRESSURE FILTERING COOLER AIR INTO THE AREA...EXPECT
HIGH TEMPS IN THE UPPER 70S FOR WED AND THU BEFORE THE RETURNING
SOUTHERLY FLOW CAN BOOST HIGHS INTO THE LOWER 80S BY FRI. 80S WILL
CONTINUE INTO SAT BEFORE THE EXPECTED PCPN WILL RESTRICT HIGHS BACK
TO AROUND 80 FOR SUN AND THE UPPER 70S FOR MON.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 225 AM EDT MON AUG 12 2013
FOG IS EXPECTED TO FORM AND THICKEN OVERNIGHT FROM NORTH TO SOUTH
ACROSS THE AREA. FOR A TIME...IT IS EXPECTED TO GET QUITE LOW AT EACH
TAF SITE. EXPECT CLEARING OF THE FOG BETWEEN 13 AND 14Z. THEN WE WILL
SEE SOME SHOWERS AND THUNDERSTORMS FORM AGAIN AROUND OR AFTER 16Z.
HAVE STARTED WITH VCTS IN THE TAFS BEFORE GOING TO STRAIGHT UP TSRA
PREVAILING BY MID AFTERNOON AT LOZ AND SME. AWAY FROM ANY STORM...
WINDS WILL BE LIGHT AND VARIABLE THROUGH THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ044-
050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
SHORT TERM...GREIF
LONG TERM...DUSTY
AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
504 AM EDT MON AUG 12 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 503 AM EDT MON AUG 12 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER
JAMES BAY WITH A WELL-DEFINED SHORTWAVE TROUGH/PV ANOMALY
TO THE WEST NEAR CYPL. A WEAK 850-700 MB TROUGH SUPPORTED SOME ISOLD
SHOWERS THROUGH N CNTRL UPPER MI AND ERN LAKE SUPERIOR. AT THE
SFC...A TROUGH EXTENDED THROUGH WRN LAKE SUPERIOR AHEAD OF A COLD
FRONT DROPPING THROUGH NRN ONTARIO TO NEAR CYGQ.
TODAY...EXPECT THAT THE NW ONTARIO SHRTWV BRUSHING UPPER MI DURING
INCREASED DAYTIME HEATING AND LAKE BREEZE BOUNDARY DEVELOPMENT...
WILL BE ENOUGH TO TRIGGER ADDITIONAL ISOLD/SCT SHOWERS OVER MAINLY
THE CNTRL AND ERN CWA. WITH MLCAPE VALUES ONLY FCST INTO THE 100-300
J/KG RANGE...AND THE STRONGER 700-300 MB QVECTOR CONV WITH THE SHRTWV
AND STEEPER MID LEVEL LAPSE RATES REMAINING TO THE NORTH...TSRA WERE
NOT MENTIONED. CLOUDS AND INCREASING NRLY FLOW WILL KEEP TEMPS BELOW
NORMAL WITH HIGHS IN THE UPPER 60S NORTH AND LOWER 70S SOUTH.
TONIGHT...ANY REMAINING SHOWERS ARE EXPECTED TO DIMINISH QUICKLY AS
SUBSIDENCE INCREASES IN THE WAKE OF THE SHRTWV AND DAYTIME HEATING
SUBSIDES. WITH CLEARING SKIES AND PWAT VALUES FALLING TO AROUND 0.50
INCH(50 PCT OR NORMAL)...TEMPS OVER THE INTERIOR WEST ARE EXPECTED
TO FALL INTO THE LOWER 40S...CLOSER TO THE LOWER END OF GUIDANCE.
LINGERING LOW LEVEL NW FLOW OVER THE EAST SHOULD STILL BE STRONG
ENOUGH TO KEEP TEMPS FROM DROPPING OFF AS MUCH WITH MINS ONLY IN THE
UPPER 40S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 309 AM EDT MON AUG 12 2013
COOL AND DRY WEATHER IS EXPECTED THROUGH THE WORK WEEK AS HIGH
PRESSURE DOMINATES THE PATTERN. A SERIES OF WEAK SHORTWAVES ROTATING
AROUND THE BACKSIDE OF AN EASTERN CANADIAN TROUGH COULD BRING SOME
INCREASED CLOUDINESS AT TIMES...BUT LITTLE IF ANY PRECIP IS
EXPECTED.
TUESDAY AND TUESDAY NIGHT...DEEP TROUGHING CENTERED OVER WESTERN
QUEBEC IS CURRENTLY COMPRISED OF A HALF DOZEN OR SO EMBEDDED
SHORTWAVES THAT ARE DEPICTED IN WV IMAGERY. ONE WAVE OVER NORTHERN
HUDSON BAY IS PROGGED TO BE MOVING SE ACROSS THE CWA AT THE START OF
THE PERIOD. THIS FEATURE HAS COMPLICATED FORECASTS FOR TUESDAY AS IT
WAS NOT PICKED UP WELL BY ANY MODEL UNTIL WITHIN THE PAST 36 HRS.
THE WAVE WILL OUTRUN PEAK HEATING...SO WITH DEPLETED MOISTURE BEHIND
TODAYS SYSTEM...CAPPING AROUND H7 BEHIND THE WAVE...AND SFC DEW
POINTS IN THE 40S...WOULD EXPECT TO SEE ONLY A DIURNAL CUMULUS FIELD
WITH POSSIBLY SOME SPRINKLES. WILL OPT TO KEEP PRECIP MENTION OUT OF
THE FORECAST ATTM...BUT WILL BOOST UP AFTERNOON CLOUD COVER A BIT.
QUITE A COOL NIGHT IS IN THE MAKING TUESDAY NIGHT AS THE AXIS OF
HIGH PRESSURE BUILDING INTO THE REGION SETTLES OVER THE WESTERN CWA.
PWAT AROUND 0.5 INCHES AND LIGHT WINDS WILL PROMOTE EXCELLENT
RADIATIONAL COOLING ACROSS THE AREA. CONTINUED TO EMPLOY
GUIDANCE...CHIEFLY BIAS CORRECTED MOS...THAT HAS PERFORMED
EXCEPTIONALLY WELL WITH SIMILAR NIGHTS OVER THE PAST SEVERAL WEEKS.
CURRENT FORECAST IS FOR UPPER 30S INTERIOR WEST TO LOW 40S ELSEWHERE
INLAND TO AROUND 50 VERY NEAR THE GREAT LAKES SHORES. ANOTHER WEAK
SHORTWAVE WILL TRACK SE ACROSS THE AREA LATE IN THE NIGHT...BUT WITH
LITTLE MOISTURE...DO NOT EVEN EXPECT MID CLOUDS.
WEDNESDAY THROUGH THURSDAY...ANOTHER WEAK WAVE WILL PUSH SE ACROSS
THE CWA WEDNESDAY MORNING...AND YET ANOTHER ONE THURSDAY MORNING.
BOTH LOOK RATHER BENIGN ATTM WITH MOISTURE STILL QUITE LOW. BOTH
DAYS SHOULD SEE SHALLOW CUMULUS DEVELOPMENT INLAND WITH SUBSTANTIAL
CAPPING AT H7. DEPARTING SFC HIGH PRESSURE WILL BRING A COUPLE MORE
COOL NIGHTS BEFORE FRIDAY. HAVE CONTINUED TO USE COLDER GUIDANCE FOR
THESE NIGHTS AS PWAT WILL STILL BE BELOW 0.7 INCHES.
FRIDAY THROUGH SUNDAY...A WARMING TREND IS IN STORE BY THE END OF
THE WEEK...WITH WIDESPREAD 70S AND A FEW 80S TIPPING THE SCALE BACK
TO ABOVE AVERAGE TEMPS. MODEL GUIDANCE IS IN DECENT AGREEMENT THAT A
TROUGH FROM WESTERN CANADA WILL BEGIN ERODING RIDGING OVER THE
NORTHERN PLAINS BY LATE THURSDAY. HOWEVER...THERE IS SOME
DISAGREEMENT AS TO THE MAGNITUDE AND DURATION OF THIS PROCESS. THE
ECMWF IS MUCH MORE CONSERVATIVE THAN THE GFS IN BRINGING THE TROUGH
INTO THE UPPER MS VALLEY...HOLDING OFF UNTIL LATE NEXT WEEKEND. THE
GFS BRINGS PRECIP INTO THE WESTERN CWA AS EARLY AS FRIDAY NIGHT.
BOTH HAVE BEEN QUITE CONSISTENT WITH THEIR RESPECTIVE FORECASTS...SO
CANNOT RULE OUT EITHER. EXPERIENCE TENDS TO LEAN TOWARD THE SLOWER
PROGRESSION OF THE ECMWF IN BREAKING DOWN A SUMMERTIME RIDGE.
HOWEVER...GIVEN UNCERTAINTY...WILL MAINTAIN CONSENSUS FORECAST OF
SLIGHT CHANCE OF SHOWERS AND STORMS BEGINNING LATE SATURDAY INTO
SUNDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 151 AM EDT MON AUG 12 2013
THE APRCH OF ANOTHER DISTURBANCE LATER THIS MRNG INTO THE AFTN
ACROSS LK SUP WL BRING A THREAT OF MORE -SHRA TO MAINLY CMX AND
SAW...BUT CONFIDENCE ATTM REMAINS TOO LO TO INCLUDE MORE THAN VCSH
IN THE TAFS. ANY SHRA WL END LATER THIS AFTN WITH DRYING/SUBSIDENCE
IN THE WAKE OF THE DEPARTING DISTURBANCE. SINCE THE LLVLS WL REMAIN
DRY THRU THE FCST PERIOD...EXPECT VFR CONDITIONS AT ALL 3 TAF SITES
EVEN IF THERE IS A -SHRA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 503 AM EDT MON AUG 12 2013
AFTER A TROUGH MOVES THROUGH LAKE SUPERIOR EARLY...A WEAK COLD FRONT
WILL MOVE THROUGH LAKE SUPERIOR TODAY. HOWEVER...WINDS ARE EXPECTED
TO REMAIN LESS THAN 20 KNOTS. HIGH PRESSURE WILL RESUME CONTROL OF
THE WRN GREAT LAKES TUESDAY THROUGH THE END OF THE WEEK TO KEEP
WINDS GENERALLY LIGHT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KLUBER
AVIATION...KC
MARINE...JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
342 AM CDT Mon Aug 12 2013
.SHORT TERM...(Today through Wednesday Afternoon)
Issued at 342 AM CDT MON AUG 12 2013
A frontal boundary settling south though the Plains States of Iowa
and Nebraska Sunday set the stage for convective development to our
north that afternoon and evening. However, much of this activity
faded with the waning of the day; with only storms at the tail end
of the front, across south central Nebraska, able to bridge from the
heating of the day to the moisture transport of the nocturnal jet.
Speaking of which, this mornings jet, while not strong, has proved
sufficient enough to develop a growing area of thunderstorms in
north central Kansas. Current expectation, supported well by short
range models like the HRRR, are that the storms in north central
Kansas will congeal across central Kansas into a MCS which will
traverse our forecast area through the morning hours, making storms
likely during the morning commute in eastern Kansas and far western
Missouri. The MCV this could leave behind across western Missouri
this morning may keep cloud cover and showers percolating across our
forecast area through the day. This activity will be assisted by a
weak frontal boundary that will also be settling into northern
Missouri today. However, at this time areal coverage looks limited
enough by the late morning to afternoon hours to warrant carrying
only chance POPs. With the advancing baroclinic zone settling south
through the day, focus for continued convection will slowly settle
with it, generally along and south of the Missouri river by tonight,
with the focus continuing its southward trek through Tuesday.
Otherwise, looking at temperatures for the next 36 hours, today will
feel a bit hot and humid in northeast Missouri --no morning rain or
cloud cover--, but areas back tot he west will both cloud cover and
rain to cope with, there have shaved a few degrees off the going
forecast on the Kansas-Missouri state line. Tuesday, will simply be
cool as the surface high behind the advancing front makes its
presents felt in earnest. Look forward to even nicer conditions in
the coming work days.
.LONG TERM...(Wednesday Evening through Sunday)
Issued at 342 AM CDT MON AUG 12 2013
Agreement among medium range models leads to a high confidence
forecast this period. The overall upper level pattern will feature
troughing over the Great Lakes and Northeastern CONUS through the
period with upper level ridging over the Rockies. This will leave
the local area in between those two main features and, under cool
northwest flow aloft. At the surface, cool Canadian high pressure
will drop south through the northern Plains and Upper Midwest
Tuesday night and move into the local area on Wednesday. This ridge
of high pressure will remain dominant over the area through the
second half of the work week and into the weekend keeping conditions
dry and temperatures below average. Highs Wednesday through Friday
will be nearly 10 degrees below average in the upper 70s to near 80.
Highs Saturday will warm a bit into the lower 80s and will further
warm Sunday with highs in the low to mid 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1206 AM CDT MON AUG 12 2013
Satellite imagery suggests convection which formed along the NE
portion of a weak cold front is in the process of forming the
anticipated MCS which will likely affect eastern KS and west central
MO shortly after sunrise. The HRRR has had the best consistency on
developing this activity and over the past several hourly runs it now
tracks the MCS in a more easterly track vs southeasterly. Given radar
trends which show the southwest portion of the MCS is tracking
southeastward I won`t be surprised if the MCS eventually ends up
tracking ese. Bottom line is the convection is looking more likely it
will affect all 3 terminals Monday morning with KMCI/KMKC having a
greater chance plus the risk for thunder. Believe cigs will drop to
just above MVFR criteria although a brief drop to MVFR is possible
early on when the MCS is likely to be stronger.
Winds will remain light through the forecast with the MCS likely
resulting in chaotic wind directions. Some question as whether or not the
weak IA/NE cold front will drift far enough southward to reach west
central MO. Not much of push behind the front but the 00z NAM is the
only model which fails to move the front that far south. Will side
with model consensus for now and move the front into west central MO
Monday evening.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Cutter
LONG TERM...73
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1217 AM CDT Mon Aug 12 2013
.SHORT TERM...(This Evening through Tuesday Afternoon)
Issued at 324 PM CDT SUN AUG 11 2013
Short term model guidance continues to suggest scattered convection
developing along surface boundary draped across central Nebraska and
northern Iowa this afternoon. However, more widespread convection
should develop across northwest Kansas and southwest Nebraska within
the next few hours as a potent shortwave begins to enter the Western
Plains.
For the local area, dry conditions will persist into the evening
hours, as soundings continue to indicate fairly dry air in the low
and mid-levels. Surface dew points have risen slowly over the
extreme western CWA as boundary layer flow has turned to the south,
but in the NERN CWA, dew points remain in the 50s. HRRR/RAP/NAM
suggest scattered convection slowly sinking southward towards the
MO/IA border towards midnight, but should dissipate before reaching
the area. We`ll have to monitor potential for the development of an
MCS over western Kansas which would then track east southeast toward
the CWA by daybreak.
Monday: What`s left of the Kansas MCS should track primarily over
southeastern Kansas and south central Missouri Monday morning. As
the upper shortwave moves though the area, additional showers may
develop further north along and ahead of the surface boundary which
will be slowly pushing to the south through the day. Temperatures
as a result will be a difficult forecast given the potential for cloud
cover and showers to significantly impact readings in some locations.
Monday night-Tuesday: Modest isentropic downglide behind a departing
shortwave should allow the area to dry out quickly Monday night with
high pressure moving into the Upper Midwest. By Tuesday we`ll
monitor the potential for a secondary shortwave to track southward
through the increasingly northwest flow aloft. Confidence low on
any impact to the CWA, thus will leave PoPs out of the forecast.
.LONG TERM...(Tuesday Evening through Sunday)
Issued at 324 PM CDT SUN AUG 11 2013
Confidence in the extended period is above average, with all signs
pointing to a prolonged period of dry weather and below normal
temperatures. This will be driven by persistent ridging across the
Rockies and downstream northwesterly flow and a sprawling surface
high across the Midwest. Minimal changes were made to model
consensus numbers in this high-confidence forecast, which will be
more characteristic of mid-September than mid-August.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1206 AM CDT MON AUG 12 2013
Satellite imagery suggests convection which formed along the NE
portion of a weak cold front is in the process of forming the
anticipated MCS which will likely affect eastern KS and west central
MO shortly after sunrise. The HRRR has had the best consistency on
developing this activity and over the past several hourly runs it now
tracks the MCS in a more easterly track vs southeasterly. Given radar
trends which show the southwest portion of the MCS is tracking
southeastward I won`t be surprised if the MCS eventually ends up
tracking ese. Bottom line is the convection is looking more likely it
will affect all 3 terminals Monday morning with KMCI/KMKC having a
greater chance plus the risk for thunder. Believe cigs will drop to
just above MVFR criteria although a brief drop to MVFR is possible
early on when the MCS is likely to be stronger.
Winds will remain light through the forecast with the MCS likely
resulting in chaotic wind directions. Some question as whether or not the
weak IA/NE cold front will drift far enough southward to reach west
central MO. Not much of push behind the front but the 00z NAM is the
only model which fails to move the front that far south. Will side
with model consensus for now and move the front into west central MO
Monday evening.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Dux
LONG TERM...Hawblitzel
AVIATION...MJ
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1121 PM CDT Sun Aug 11 2013
.UPDATE:
Issued at 958 PM CDT Sun Aug 11 2013
No significant changes made. Adjusted cloud cover upwards based on
thicker mid/high level deck advancing from KS and wrn MO.
Otherwise just minor adjustments to capture short term trends.
Overnight lows still look on track.
2%
&&
.SHORT TERM: (Through Late Tonight)
Issued at 313 PM CDT Sun Aug 11 2013
Low level flow is turning back around to the south across southern
and central Missouri. Already seeing cumulus spread up to near
California Missouri and points west-northwest. A weak low level jet
develops tonight which produces some decent moisture convergence at
850mb primarily over southern portions of the CWFA. It doesn`t look
like the forcing is strong enough to produce very widespread or
organized convection, however the RUC is showing about 900 J/KG CAPE
in the region of moisture convergence, and the CAPE is fairly tall
extending up to 35,000ft. Certainly can`t rule out isolated-widely
scattered showers and thunderstorms over southeast Missouri and
possibly parts of east central and central Missouri as well, though
the lift drops off further north. Lows will be warmer tonight due
to the increasing cloud cover and southerly flow.
Carney
.LONG TERM: (Monday through Next Sunday)
Issued at 313 PM CDT Sun Aug 11 2013
Main concern continues to be thunderstorms chances early this week.
Scattered thunderstorms may be ongoing over the eastern Ozarks into
southern Illinois early Monday on the nose of a veering low level
jet. Better chance of storms will be focused along a cold front
that enters the northern CWFA early in the day and moves slowly
south through the day. Atmosphere will become increasingly
unstable along and ahead of the front with MLCAPEs around 1,000
J/kg with some weak CIN. This should be enough to generate
scattered thunderstorms given weak large scale ascent from a
passing shortwave. There may be a few strong storms that could
producing some gusty winds given the relatively dry low-mid levels
seen on the forecast soundings, though deep layer shear of only
25-30 knots will limit overall severe threat.
Not too many changes to previous thinking that rain chances will
diminish from north to south on Monday Night and Tuesday as the
front slowly moves south into the Mid South. Still have a dry
forecast going mid to late week as an impressive surface ridge
creeps southward through the area. Easterly low level flow and
850mb temperatures around 10C should keep temperatures below mid
August normals from Wednesday into Friday. Latest runs of the
GFS/ECMWF do agree that an upper trough will deepen over Missouri
and Illinois by Saturday. There will be Gulf moisture drawn
northward ahead of this trough, though any rain looks like it will
stay just south and east of us next weekend. 850mb temperatures
will warm into the mid-teens causing temperatures to climb closer
to normal by next weekend.
Britt
&&
.AVIATION: (For the 06z TAFs through 06z Monday Night)
Issued at 1108 PM CDT Sun Aug 11 2013
Low-mid level cloudiness will spread nwd into the taf sites late
tonight as moisture spreads nwd. Could not rule out isolated
convection towards morning in COU and the St Louis metro
area...but the better chance should occur Monday afternoon with
the approach of an upper level disturbance from the west and a
cold front from the north. There should be at least scattered
showers and thunderstorms on Monday and will include either vcts
or prob30 in the tafs for tsra. Mainly a light sely sfc wind late
tonight...then the wind will veer around to a w-swly direction by
Monday afternoon...and a w-nwly direction Monday evening after
fropa.
Specifics for KSTL: Low-mid level cloudiness will advect nwd into
STL late tonight. There could be a few showers or thunderstorms
already towards morning...but may leave the STL taf forecast dry
until Monday afternoon. Light sely sfc wind will increase to 7 kts
on Monday...and veer around to a wly direction Monday afternoon
and a nwly direction Monday night.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
140 AM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 119 AM CDT MON AUG 12 2013
UPDATED THE FORECAST OVERNIGHT TO INCREASE CHANCES OF PRECIPITATION
IN THE SOUTHERN CWA AS THE COLD FRONT SINKS SOUTH...AIDED BY
OUTFLOW...AND DECREASE CHANCES IN THE NORTH...ALTHOUGH I HAVE NOT
COMPLETELY REMOVED CHANCES...BECAUSE EVEN IN OUR NORTH WE SEEM TO
BE GETTING SOME SPURIOUS ELEVATED CONVECTION HERE AND THERE.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 245 PM CDT SUN AUG 11 2013
A SURFACE TROUGH OF LOW PRESSURE ACROSS NORTHERN NEBRASKA THIS
AFTERNOON IS EXPECTED TO PROVIDE ENOUGH CONVERGENCE FOR THE
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE OUTLOOK
AREA BY LATE AFTERNOON AS THE CAP BEGINS TO WEAKEN. WHILE THE
INSTABILITY VALUES REMAIN HIGH...ON THE ORDER OF 3000 J/KG OF MU
CAPE...THE WIND SHEAR VALUES ARE VERY WEAK...AND PRIMARY CONCERN
WITH THESE STORMS WILL BE THE POTENTIAL FOR LARGE HAIL. MODELED
SOUNDINGS ALSO INDICATE AN INVERTED V ATMOSPHERIC PROFILE FOR THE
LATE AFTERNOON AND EARLY EVENING HOURS...SO STRONG WIND GUSTS MAY
ALSO BE A CONCERN. NOT SURPRISINGLY...THE ENTIRE OUTLOOK ARE
REMAINS IN A SLIGHT RISK FOR SEVERE WEATHER FROM SPC...WITH LARGE
HAIL AND WINDS BEING THE PRIMARY CONCERN.
SOME OF THE LATEST MODEL RUNS ARE INDICATING THE CONVECTION
CURRENTLY DEVELOPING ACROSS THE HIGH PLAINS AND ASSOCIATED WITH A
PASSING SHORTWAVE IN WV IMAGERY...WILL EVENTUALLY MERGE WITH
CONVECTION IN PROXIMITY OF THE SURFACE TROUGH...WHICH COULD RESULT
IN AN ACTIVE EVENING...PRECIPITATION WISE...ACROSS THE LOCAL
AREA. THE 12Z WRF APPEARS TO BE THE MOST AGGRESSIVE WITH THE
SCENARIO...AND THE 18Z RAP ALSO HINTING AT A SOLUTION SIMILAR TO
THIS...SO FELT CONFIDENT ENOUGH TO INCREASE POPS THROUGH THE EARLY
EVENING HOURS INTO THE 50 PERCENT RANGE ACROSS MOST OF THE AREA.
OTHERWISE...WITH THE SLOW MOVEMENT OF ANY STORMS THAT DO
DEVELOP...HEAVY RAINFALL WILL ALSO BE A CONCERN...AND CONTINUED
WITH THE POTENTIAL FOR VERY LOCALIZED FLOODING THIS EVENING AND
OVERNIGHT.
FOR MONDAY...EXPECT A MOSTLY DRY START TO THE DAY...WITH
INCREASING CHANCES FOR PRECIPITATION BY AFTERNOON AS WE COULD SEE
SOME CONVECTION REDEVELOP IN THE VICINITY OF THE STALLED OUT
FRONT/TROUGH WHICH WILL THEN BE ACROSS NORTH CENTRAL KANSAS.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 245 PM CDT SUN AUG 11 2013
COOLER THAN NORMAL SUMMER WEATHER WILL SETTLE IN ACROSS OUR REGION
FOR MUCH OF THE WORKWEEK IN A NORTHWEST FLOW REGIME ACROSS THE
CENTRAL PLAINS. WARMER AIR WILL RESIDE TO THE WEST FM THE DESERT SW
NORTH ACROSS THE ROCKIES...WHILE TO THE EAST...A TROUGH NEAR THE
HUDSON BAY WILL DEEPEN AND TRANSLATE ACROSS THE EASTERN CONUS.
COOLER AIR WILL BACK IN ACROSS THE PLAINS FM THE UPPER MIDWEST AND A
1022ISH MB SFC HIGH WILL BUILD SOUTH FM THIS AREA ONTO THE PLAINS...AND
WILL REINFORCE THE COOLER AIRMASS UNTIL AROUND THE THURSDAY TIME
FRAME. BY THE END OF THE WEEK AND HEADING INTO THE WEEKEND...THE
SFC RIDGE AXIS SLIDES EAST AND THE UPPER RIDGE OVER THE ROCKIES WILL
BEGINS TO BUILD TOWARDS THE PLAINS AND TEMPERATURES WILL BEGIN TO
MODERATE CLOSER TO SEASONAL NORMALS.
FOR CONVECTIVE POTENTIAL...CANNOT RULE OUT TSTM CHANCES DURING THIS
TIME FRAME...WITH DEVELOPMENT DEPENDENT UPON BOUNDARY LOCATIONS AND
TIMING OF WAVES. ON MONDAY...A FEW STORMS MAY LINGER IN THE
MORNING...WITH REDEVELOPMENT POSSIBLE DURING THE DAY ALONG A BACK
DOOR COOL FRONTAL BOUNDARY AND ALSO TO THE WEST IN AN UPSLOPE FLOW
REGIME. A STRONG TO SEVERE STORM IS POSSIBLE IN SUFFICIENT
INSTABILITY...BUT SHEAR REMAINS WEAK. THE BETTER PCPN CHCS BEGIN TO
FOCUS TO OUR WEST THROUGH MID WEEK...WITH SOME POTENTIAL FOR HIGH
PLAINS CONVECTION TO MIGRATE EAST TOWARDS OUR WESTERN CWA. AS
PATTERN CONTINUES TO AMPLIFY...FOCUS TURNS MORE TO TIMING OF WAVES
TOPPING RIDGE AND CROSSING THE PLAINS...WITH HIT OR MISS CHCS FOR
THE OUTER PERIODS...BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE
POPS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 119 AM CDT MON AUG 12 2013
SHOWER AND THUNDERSTORM ACTIVITY SHOULD WANE AS THE COLD FRONT TO
THE SOUTH OF THE TERMINAL CONTINUES TO MOVE SOUTH. EVEN THOUGH
WIND DIRECTION WILL SHIFT TO THE NORTH...IT WILL REMAIN
LIGHT...AND WILL ALLOW SOME REDUCED VISIBILITY TO DEVELOP AS A
RESULT OF THE RECENT RAINFALL AND STILL ELEVATED DEWPOINTS.
CEILINGS SHOULD REMAIN IN THE MID-HIGH LEVELS.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...HEINLEIN
SHORT TERM...SAR
LONG TERM...FAY
AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
350 AM CDT MON AUG 12 2013
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
CHALLENGE FOR THE FORECAST TODAY WILL BE SHOWERS IF ANY ALONG THE
BACK DOOR COLD FRONT SLIDING SOUTH OUT OF MANITOBA...CURRENTLY
NORTH OF WINNIPEG. CLOUDS ASSOCIATED WITH FRONT MAY CAUSE SOME
UNCERTAINTY WITH TEMPS HOWEVER CURRENT TIMING OF FROPA WILL STILL
GIVE MUCH OF THE AREA GOOD SOLAR THIS AFTERNOON. ALSO MOISTURE IS
LIMITED WITH MOSTLY A MID LEVEL BAND OF CLOUDS WHICH WILL BE FAIRLY
NARROW. WILL MAINTAIN HIGH TEMPS THIS AFTERNOON SIMILAR TO
YESTERDAYS MID TO UPPER 70S.
AS FOR POPS AND COVERAGE...IF ANYTHING ISOLATED SHOWERS AT BEST.
BEST FORCING REMAINS EAST CLOSER TO VORT LOBE AND SFC LOW PRESSURE
ACROSS THE NORTHERN GREAT LAKES. EC QPFS PAINT SOME VERY LIGHT
AMOUNTS ACROSS THE NORTHERN VALLEY AND UPPER DEVILS LAKE BASIN.
HAVE LEFT THIS AREA DRY AND KEPT THE SLIGHT POPS IN NW MN FOR THE
LATE MORNING AND INTO THE AFTERNOON. THIS AREA IS WHERE THE 00Z
GFS...06Z NAM AND THE 06Z HRRR HAVE SOME LIGHT QPF.
1025MB CANADIAN HIGH PRESSURE TO BUILD IN BEHIND FROPA THIS EVENING
AND CENTER OVER S MANITOBA BY TUESDAY MORNING. NORTHERLY WINDS LOWER
PWATS DOWN TO AROUND HALF AN INCH...CAUSING CLEAR SKIES AND COOL
TEMPS MONDAY NIGHT INTO TUESDAY MORNING. HAVE KEPT FOG MENTION
OUT OF THE FORECAST WITH NO RECENT PRECIP BUT WOULD NOT BE
SURPRISED TO SEE SOME SHALLOW GROUND FOG DEVELOP. WILL KEEP OUT OF
GRIDS FOR NOW. HIGH TEMPS TUESDAY VERY SIMILAR TO MONDAY A DEGREE
OR TOW COOLER AS THERMAL PROFILE MAY BE A TOUCH LOWER THAN MONDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
TUESDAY NIGHT THRU WEDNESDAY NIGHT...THE SFC HIGH PRESSURE SYSTEM
SLOWLY DRIFTS ACROSS THE FA AS 500MB CONFLUENT FLOW CONTINUES.
LITTLE TO NO CHANGE IN THERMAL PROFILE. HIGHS IN THE 70S WITH
LOWS IN THE UPPER 40S NORTH AND LOW 50S SOUTH.
THURSDAY THROUGH SUNDAY...LONG RANGE MODELS CONTINUE TO POINT TO
A SIGNIFICANT WARM UP FOR THE EXTENDED PERIOD. THERE APPEARS TO BE
HIGHER CONFIDENCE THAT THE RIDGE AXIS OVER THE ROCKIES WILL
TRANSLATE EASTWARD OVER THE NORTHERN PLAINS LATE THIS WEEK INTO
THE WEEKEND. THE WARMING TREND MAY PERSIST WELL INTO NEXT WEEK AND
BE THE MOST PROLONGED STRETCH OF ABOVE NORMAL TEMPERATURES FOR
THIS PART OF THE COUNTRY SO FAR THIS SUMMER. THE TIME PERIOD FOR
SIGNIFICANT AND WIDESPREAD PRECIPITATION NOW LOOKS LIKE IT MAY
HOLD OFF UNTIL NEXT SUNDAY. IT APPEARS THAT WE MAY EXPERIENCE SOME
MCS ACTIVITY DUE TO COMPLEXES RIDING OVER THE RIDGE AXIS WHICH
SHOULD BE IN PLACE OVER THE AREA. DUE TO THE INCREASINGLY DRY
CONDITIONS OVER THE REGION AS INDICATED BY THE LATEST DROUGHT
MONITOR...ANY SUBSTANTIAL RAINFALL WOULD BE A WELCOME RELIEF.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1121 PM CDT SUN AUG 11 2013
WILL SEE SOME VFR CIGS SWING THROUGH NE FA...BJI...TAF SITE DURING
THE MORNING AS AN UPPER LEVEL DISTURBANCE SWINGS THROUGH S
MB/ONTARIO. OTHERWISE NO CIGS EXPECTED. IN SPITE OF SKC AND LIGHT
WINDS STILL NOT ENOUGH CONFIDENCE ON FOG POTENTIAL TO INCLUDE IN
TAFS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SHORT TERM...JK
LONG TERM...BRAMER/JK
AVIATION...VOELKER
AREA FORECAST DISCUSSION
NWS TULSA OK
311 AM CDT MON AUG 12 2013
.DISCUSSION...
THE MAIN CONCERN WITH THE FORECAST THIS MORNING IS THE POTENTIAL FOR
A PROLONGED PERIOD OF INTERMITTENT HEAVY RAINFALL OVER THE NEXT
COUPLE OF DAYS... WITH THE POSSIBILITY OF RENEWED FLOODING ISSUES
ACROSS MUCH OF THE AREA.
CONVECTIVE ACTIVITY CURRENTLY ONGOING ACROSS WESTERN AND CENTRAL
OKLAHOMA IS FORECAST TO SPREAD EASTWARD ACROSS THE FORECAST AREA
DURING THE DAY TODAY. BOTH THE LOCAL WRF AND THE HRRR DEPICT THIS AS
REMAINING MOSTLY SCATTERED IN NATURE. HOWEVER... ANY HEAVIER STORMS
OR TRAINING OF CELLS COULD QUICKLY LEAD TO LOCALIZED FLOODING...
GIVEN THE AMOUNTS OF RAINFALL THE AREA HAS RECEIVED OF LATE. THERE
WILL ALSO BE THE POTENTIAL FOR STORMS TO BECOME STRONG TO SEVERE
DURING THE DAY TODAY GIVEN THE AMOUNT OF INSTABILITY AND SHEAR PRESENT.
THE MAIN THREAT FOR WIDESPREAD HEAVY RAINFALL WILL BEGIN OVERNIGHT
TONIGHT. SEVERAL ROUNDS OF HEAVY THUNDERSTORMS WILL LIKELY AFFECT
THE REGION THROUGH TUESDAY UNTIL A COLD FRONT SWEEPS SOUTHWARD
THROUGH THE REGION BRINGING DRIER AIR INTO THE AREA. A FLASH FLOOD
WATCH WILL BECOME EFFECTIVE THIS MORNING THROUGH 0Z TUESDAY.
DEPENDING ON THE EVOLUTION OF THE EVENT AND PROGRESS OF THE FRONT...
THIS WATCH MAY EVENTUALLY NEED TO BE EXTENDED IN TIME INTO TUESDAY
EVENING.
SCATTERED PRECIPITATION MAY LAST THROUGH THE DAY WEDNESDAY. HOWEVER...
AFTER THAT... DRY AND MILD CONDITIONS WILL PREVAIL INTO AND THROUGH
THE UPCOMING WEEKEND. SOME OF THE COOLEST OVERNIGHT LOWS OF THE
SEASON WILL OCCUR THURSDAY THROUGH SATURDAY MORNINGS. READINGS IN
NORTHWEST ARKANSAS ARE EXPECTED TO DIP INTO THE 50S... WITH LOW TO
MID 60S ACROSS MUCH OF THE REST OF THE FORECAST AREA. DAYTIME HIGH
TEMPERATURES WILL CONTINUE TO RUN BELOW SEASONAL AVERAGES... AND
WITH DEWPOINTS IN THE UPPER 50S TO LOWER 60S SHOULD FEEL QUITE
UNSEASONABLY PLEASANT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 89 72 84 70 / 60 40 60 50
FSM 91 73 86 71 / 60 60 70 70
MLC 95 73 89 71 / 20 50 70 70
BVO 88 70 83 68 / 80 40 50 50
FYV 85 68 83 67 / 80 70 60 50
BYV 83 68 83 65 / 80 70 50 40
MKO 90 72 84 70 / 70 40 70 60
MIO 86 69 85 66 / 80 30 40 40
F10 92 73 85 70 / 30 40 70 70
HHW 95 75 94 73 / 10 30 30 50
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FLASH FLOOD WATCH FROM 7 AM MONDAY TO 7 PM TUESDAY FOR OKZ054-
OKZ055-OKZ056-OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-OKZ062-
OKZ063-OKZ064-OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-OKZ070-
OKZ071-OKZ072-OKZ073-OKZ074-OKZ075-OKZ076.
AR...FLASH FLOOD WATCH FROM 7 AM MONDAY TO 7 PM TUESDAY FOR ARZ001-
ARZ002-ARZ010-ARZ011-ARZ019-ARZ020-ARZ029.
&&
$$
SHORT TERM...07
LONG TERM....06
AREA FORECAST DISCUSSION
NWS NORMAN OK
1210 AM CDT MON AUG 12 2013
.AVIATION...
SHOWERS/TSTMS CONTINUE TO ADVANCE NEWD THROUGH WRN OK. WILL INCLUDE PREVAILING
OR TEMPO TSRA IN MOST SITES EARLY IN THE PD. EXPECT ACTIVITY TO
GRDLY DIMINISH LATER THIS MORNING. MORE STORMS LIKELY TO REDEVELOP
LATER THIS AFTERNOON AND TONIGHT...ESP ACROSS NRN OK. OUTSIDE THE
THUNDERSTORMS...GENERALLY VFR CONDITIONS WILL PREVAIL.
&&
.PREV DISCUSSION... /ISSUED 915 PM CDT SUN AUG 11 2013/
.DISCUSSION...
A COUPLE OF CLUSTERS OF THUNDERSTORMS OVER SOUTHWEST OKLAHOMA AND
WESTERN NORTH TEXAS ARE LIKELY TO PERSIST THROUGH THE LATE
EVENING. SHORT-RANGE MODELS SUGGEST THAT CONVECTION WILL SHIFT
INTO NORTHWEST OKLAHOMA AFTER MIDNIGHT...AND PERHAPS FORM INTO AN
MCS ACROSS NORTHERN OKLAHOMA AND SOUTHERN KANSAS. THIS SCENARIO IS
STILL FAIRLY UNCERTAIN...SO THE EXISTING OVERNIGHT
POPS...QPF...ETC. STILL LOOK REASONABLE. THE FORECAST WAS UPDATED
EARLIER TO ACCOUNT FOR THE CONVECTIVE CLUSTERS...AND ADDITIONAL
UPDATES MAY BE NEEDED FOR SHORT-TERM TRENDS THIS
EVENING/OVERNIGHT.
OTHERWISE...NO CHANGES ARE CURRENTLY PLANNED FOR THE FORECAST.
&&
.PREV DISCUSSION... /ISSUED 641 PM CDT SUN AUG 11 2013/
AVIATION...
12/00Z TAFS...VFR CONDITIONS EXPECTED TO PREVAIL ACROSS THE REGION
OUTSIDE OF ANTICIPATED TSRA. FAIRLY WIDE VARIETY OF MODEL
SOLUTIONS ON EVOLUTION OF STORMS THIS EVENING THROUGH TOMORROW.
TAFS WILL BE BASED PRIMARILY ON HRRR AND WRF...WHICH YIELD
POTENTIAL FOR TSRA TO LINGER ACROSS SW OKLAHOMA THIS EVENING AND
COMPLEX OF STORMS TO APPROACH NORTHERN OKLAHOMA TOWARD 09Z FROM
KANSAS. THIS COMPLEX PROGD TO WEAKEN AND REDEVELOPMENT ACROSS
CENTRAL PORTIONS OF OKLAHOMA TOMORROW AFTERNOON.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 73 92 72 90 / 20 30 40 40
HOBART OK 73 95 72 93 / 70 30 20 40
WICHITA FALLS TX 74 99 74 96 / 40 10 10 20
GAGE OK 69 93 68 87 / 50 40 40 50
PONCA CITY OK 71 90 69 86 / 40 40 60 50
DURANT OK 75 96 73 94 / 10 10 20 30
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
23/11
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
547 AM EDT MON AUG 12 2013
.SYNOPSIS...
LOOK FOR A MILD AND INCREASINGLY HUMID DAY TODAY ACROSS THE
REGION...AHEAD OF THE ARRIVAL OF A STRONG COLD FRONT PASSAGE ON
TUESDAY. THERE WILL BE A COUPLE WEAK WEATHER DISTURBANCES MOVING
ACROSS THE AREA WHICH COULD TOUCH OFF BRIEF SHOWERS AND
THUNDERSTORMS TODAY...BUT MOST OF THE AREA WILL BE FREE OF
SIGNIFICANT RAINFALL. BEHIND THE COLD FRONT ON TUESDAY...ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
GENERAL DECREASE IN ACTIVITY THE LAST COUPLE HOURS...ACTIVITY
CONFINED TO SE QUARTER OF THE CWA. STORMS HAVE PRODUCED HEAVY
DOWNPOURS BUT MOVING JUST FAST ENOUGH TO PRECLUDE ANY FLOODING.
SCAP1 IN SCHUYLKILL COUNTY REPORTED .47 IN 35 MINUTES EARLIER THIS
MORNING. LATEST RUC AND HRRR SHOWS MOST OF THE CONVECTION
TAPERING OFF IN THE NEXT COUPLE HOURS. AFTER LOW CLOUDS DIMINISH
THIS MORNING THE REGION WILL SEE VARIABLE CLOUDS WITH A SLIGHT
CHANCE OF SHOWERS OR THUNDERSHOWERS...WITH THE HIGHEST CHANCES
OVER THE NW AND SE PORTIONS OF THE CWA...BUT SIMILAR TO
SUNDAY...MOST OF THE REGION WILL MISS OUT ON ANY SIGNIFICANT
RAINFALL. TEMPERATURES WILL BE CLOSE TO AVERAGE...THOUGH IT WILL
BE MORE HUMID AHEAD OF THE APPROACHING FRONT ARRIVING ON TUESDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
THE STRONG FRONTAL SYSTEM WILL BECOME THE PRIMARY WEATHER FOCUS.
FRONTAL TIMING SUGGESTS CHANCE RAIN AND THUNDER COMES UP AFTER
MIDNIGHT IN WESTERN AREAS MOVING EASTWARD WITH TIME DURING
OVERNIGHT INTO TUESDAY MORNING. TIMING OF FRONTAL PASSAGE COULD
BE SUCH THAT TUESDAY AFTERNOON COULD TURN OUT DRIER...AND FORECAST
SHOWS POPS LOWERING IN THE SECOND HALF OF AFTERNOON WEST TO EAST.
QPF LOOKS RATHER LIGHT WITH PW PLUME NOT ALL THAT IMPRESSIVE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
POST FRONTAL THROUGH THURSDAY WITH A DRY AND COOL /FOR AUGUST/
PATTERN WITH ROCKY MOUNTAIN UPPER RIDGE AND DOWNSTREAM LONG WAVE
TROF FROM EASTERN CANADA TO THE MID ATLANTIC REGION. BOTH TUESDAY
AND WEDNESDAY MORNINGS LOOK VERY COOL ESPECIALLY ALONG THE
NORTHERN ZONES. FLOW TURNS SW BY FRIDAY AND THE WEEKEND FOR MILDER
TEMPERATURES AND A RETURN OF HIGHER HUMIDITY`S.
&&
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
WIDE RANGE OF CONDITIONS. UNV IS MAINLY CLR NOW...SOME LOWER
CIGS AND DENSE FOG TO THE SOUTH. VAD WINDS SUGGEST COOL AIR
LESS THAN 6000 DEEP THE LAST FEW DAYS. 09Z TAFS ADJUSTED
FOR CURRENT CONDITIONS.
EARLIER DISCUSSION BELOW.
AS BEEN THE CASE THIS SUMMER...SHOWERS FORM ALMOST EVERY DAY.
CURRENT ACTIVITY IS NOW MAINLY EAST OF INTERSTATE 99...WITH
A FEW HEAVY DOWNPOURS AND A RUMBLE OF THUNDER. ALSO ACROSS
THE SOUTHERN AREAS IS SOME FOG AND LOWER CIGS. STILL MAINLY
CLEAR TO THE NORTH. EXPECT LITTLE CHANGE BEFORE MID MORNING.
AFTER MID MORNING...EXPECT MAINLY VFR CONDITIONS. THERE WILL
STILL BE A CHC OF SHOWERS AND PERHAPS A FEW THUNDERTORMS
ACROSS THE SOUTH THIS AFT AND EVENING.
AT THE SAME TIME...SOME SHOWERS AND STORMS COULD FORM
ACROSS NORTHERN PA LATER TODAY. OVERALL A COMPLEX PATTERN.
STRONG COLD FRONT TO MOVE ACROSS THE REGION LATE TUESDAY.
EXPECT BANDS OF SHOWERS AND THUNDERSTORMS TO FORM. DYNAMICS
LAG THE FRONT SOME...BUT STILL SOME CONCERN FOR STRONG WINDS
WITH ANY STORMS.
WINDY ON WED...AS COLDER AIR WORKS SOUTHWARD.
LOOKING AT DRY CONDITIONS AFT WED.
OUTLOOK...
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS.
WED-FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...ROSS
SHORT TERM...ROSS
LONG TERM...ROSS
AVIATION...MARTIN/RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
523 AM EDT MON AUG 12 2013
.SYNOPSIS...
LOOK FOR A MILD AND INCREASINGLY HUMID DAY TODAY ACROSS THE
REGION...AHEAD OF THE ARRIVAL OF A STRONG COLD FRONT PASSAGE ON
TUESDAY. THERE WILL BE A COUPLE WEAK WEATHER DISTURBANCES MOVING
ACROSS THE AREA WHICH COULD TOUCH OFF BRIEF SHOWERS AND
THUNDERSTORMS TODAY...BUT MOST OF THE AREA WILL BE FREE OF
SIGNIFICANT RAINFALL. BEHIND THE COLD FRONT ON TUESDAY...ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
GENERAL DECREASE IN ACTIVITY THE LAST COUPLE HOURS...ACTIVITY
CONFINED TO SE QUARTER OF THE CWA. STORMS HAVE PRODUCED HEAVY
DOWNPOURS BUT MOVING JUST FAST ENOUGH TO PRECLUDE ANY FLOODING.
SCAP1 IN SCHUYLKILL COUNTY REPORTED .47 IN 35 MINUTES EARLIER THIS
MORNING. LATEST RUC AND HRRR SHOWS MOST OF THE CONVECTION
TAPERING OFF IN THE NEXT COUPLE HOURS. AFTER LOW CLOUDS DIMINISH
THIS MORNING THE REGION WILL SEE VARIABLE CLOUDS WITH A SLIGHT
CHANCE OF SHOWERS OR THUNDERSHOWERS...WITH THE HIGHEST CHANCES
OVER THE NW AND SE PORTIONS OF THE CWA...BUT SIMILAR TO
SUNDAY...MOST OF THE REGION WILL MISS OUT ON ANY SIGNIFICANT
RAINFALL. TEMPERATURES WILL BE CLOSE TO AVERAGE...THOUGH IT WILL
BE MORE HUMID AHEAD OF THE APPROACHING FRONT ARRIVING ON TUESDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
THE STRONG FRONTAL SYSTEM WILL BECOME THE PRIMARY WEATHER FOCUS. FRONTAL
TIMING SUGGESTS CHANCE RAIN AND THUNDER COMES UP AFTER MIDNIGHT IN
WESTERN AREAS MOVING EASTWARD WITH TIME DURING OVERNIGHT INTO
TUESDAY MORNING. TIMING OF FRONTAL PASSAGE COULD BE SUCH THAT TUESDAY
AFTERNOON COULD TURN OUT DRIER...AND FORECAST SHOWS POPS LOWERING
IN THE SECOND HALF OF AFTERNOON WEST TO EAST. QPF LOOKS RATHER
LIGHT WITH PW PLUME NOT ALL THAT IMPRESSIVE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
POST FRONTAL THROUGH THURSDAY WITH A DRY AND COOL /FOR AUGUST/
PATTERN WITH ROCKY MOUNTAIN UPPER RIDGE AND DOWNSTREAM LONG WAVE
TROF FROM EASTERN CANADA TO THE MID ATLANTIC REGION. BOTH TUESDAY
AND WEDNESDAY MORNINGS LOOK VERY COOL ESPECIALLY ALONG THE
NORTHERN ZONES. FLOW TURNS SW BY FRIDAY AND THE WEEKEND FOR MILDER
TEMPERATURES AND A RETURN OF HIGHER HUMIDITY`S.
&&
.AVIATION /10Z MONDAY THROUGH FRIDAY/...
AS BEEN THE CASE THIS SUMMER...SHOWERS FORM ALMOST EVERY DAY.
CURRENT ACTIVITY IS NOW MAINLY EAST OF INTERSTATE 99...WITH
A FEW HEAVY DOWNPOURS AND A RUMBLE OF THUNDER. ALSO ACROSS
THE SOUTHERN AREAS IS SOME FOG AND LOWER CIGS. STILL MAINLY
CLEAR TO THE NORTH. EXPECT LITTLE CHANGE BEFORE MID MORNING.
AFTER MID MORNING...EXPECT MAINLY VFR CONDITIONS. THERE WILL
STILL BE A CHC OF SHOWERS AND PERHAPS A FEW THUNDERTORMS
ACROSS THE SOUTH THIS AFT AND EVENING.
AT THE SAME TIME...SOME SHOWERS AND STORMS COULD FORM
ACROSS NORTHERN PA LATER TODAY. OVERALL A COMPLEX PATTERN.
STRONG COLD FRONT TO MOVE ACROSS THE REGION LATE TUESDAY.
EXPECT BANDS OF SHOWERS AND THUNDERSTORMS TO FORM. DYNAMICS
LAG THE FRONT SOME...BUT STILL SOME CONCERN FOR STRONG WINDS
WITH ANY STORMS.
WINDY ON WED...AS COLDER AIR WORKS SOUTHWARD.
LOOKING AT DRY CONDITIONS AFT WED.
OUTLOOK...
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS.
WED-FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...ROSS
SHORT TERM...ROSS
LONG TERM...ROSS
AVIATION...MARTIN/RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
221 AM EDT MON AUG 12 2013
.SYNOPSIS...
LOOK FOR A MILD AND INCREASINGLY HUMID DAY TODAY ACROSS THE
REGION...AHEAD OF THE ARRIVAL OF A STRONG COLD FRONT PASSAGE ON
TUESDAY. THERE WILL BE A COUPLE WEAK WEATHER DISTURBANCES MOVING
ACROSS THE AREA WHICH COULD TOUCH OFF BRIEF SHOWERS AND
THUNDERSTORMS TODAY...BUT MOST OF THE AREA WILL BE FREE OF
SIGNIFICANT RAINFALL. BEHIND THE COLD FRONT ON TUESDAY...ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
TRACKING SEVERAL AREAS OF CONVECTION MOVING ACROSS SOUTHERN ZONES
EARLY THIS MORNING. STORMS ARE PUTTING DOWN SOME HEAVY DOWNPOURS
BUT FORTUNATELY THEY ARE MOVING FAST ENOUGH TO PREVENT SIGNIFICANT
ACCUMULATIONS. LOOKING AT LATEST RUC AND HRRR RUNS SHOWS MOST OF
THE CONVECTION TAPERING OFF FOR ALL BUT THE EXTREME SW CORNER OF
THE CWA WHERE SHOWERS WILL LIKELY PERSIST UNTIL AFTER SUNRISE.
AFTER LOW CLOUDS DIMINISH THIS MORNING THE REGION WILL SEE
VARIABLE CLOUDS WITH A SLIGHT CHANCE OF SHOWERS OR
THUNDERSHOWERS...WITH THE HIGHEST CHANCES OVER THE NW AND SE
PORTIONS OF THE CWA...BUT SIMILAR TO SUNDAY...MOST OF THE REGION WILL
MISS OUT ON ANY SIGNIFICANT RAINFALL. TEMPERATURES WILL BE CLOSE TO
AVERAGE...THOUGH IT WILL BE MORE HUMID AHEAD OF THE APPROACHING
FRONT ARRIVING ON TUESDAY.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
THE STRONG FRONTAL SYSTEM WILL BECOME AN ISSUE OVERNIGHT MONDAY
INTO TUESDAY. FRONTAL TIMING SUGGESTS CHANCE RAIN AND THUNDER
COMES UP AFTER MIDNIGHT IN WESTERN AREAS AND STROLLS EASTWARD WITH
TIME DURING OVERNIGHT INTO TUESDAY MORNING. IF THE FRONT SPEEDS UP
TUESDAY AFTERNOON COULD TURN OUT OKAY. TRIED TO SHOW POPS LOWERING
IN THE SECOND HALF OF AFTERNOON WEST TO EAST.
ALWAYS A POP PROBLEMS AS SREF HAS THE PATTERN OF DECREASED POPS
BUT IT IS SO WET BIASED ONE CANNOT USE IT EFFECTIVELY IN GRIDS.
THE GEFS SHOWS LOWER POPS AFTER 18Z TUESDAY AS DO ALL THE
MODELS...NAM/GFS. SUSPECT PW TELLS US TWO IMPORTANT THINGS 1) NOT
GOING TO BE A BIG RAIN EVENT AND 2) PW DROPS IN AFTERNOON IMPLYING
THE AFTERNOON COULD BE RAIN FREE IN WEST. POPS REFLECT THIS
THINKING AS BEST AS PRACTICABLE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
GENERALLY COSMETIC CHANGES MADE TO PREVIOUS EXTENDED FORECAST
TODAY AS PATTERN WILL BE DOMINATED BY THE ROCKY MOUNTAIN UPPER
RIDGE AND DOWNSTREAM LONG WAVE TROF FROM EASTERN CANADA TO THE MID
ATLANTIC REGION THIS WEEK.
BEST CHANCE OF PRECIPITATION WILL COME FROM A FRONTAL SYSTEM
MONDAY NIGHT AND TUESDAY BEFORE THE MEAN UPPER TROF AXIS SETTLES
EAST OF THE AREA FOR THE LATTER HALF OF THIS WEEK. AS PREVIOUSLY
MENTIONED...THE BIGGEST IMPACT WILL BE A FRESH SHOT OF DRIER AND
COOLER AIR FOR THE MIDDLE OF THE WEEK AS TEMPERATURES DROP BELOW
AVERAGE ON WED AND THU. FLOW BEGINS TO TURN SW LATE IN THE PERIOD
FOR SOME MODERATION AS THE WEEKEND APPROACHES.
LATE IN THE PERIOD...WESTERN ATLANTIC UPPER RIDGE RETROGRADES AND
AMPLIFIES OVER BERMUDA. THIS WILL HELP TO SHARPEN THE EAST COAST
TROF AXIS AND DIRECT DEEPER LAYER MOISTURE NORTHWARD INTO THE MID
ATLANTIC REGION NEXT WEEKEND. HAVE INTRODUCED SHOWER CHANCES AS A
RESULT...MAINLY ON SUNDAY. GULF COAST TROPICAL DEVELOPMENT IS
POSSIBLE WITH THIS SURGE OF MOISTURE...SO WE`LL BE WATCHING THIS
WITH INTEREST AS THE WEEK PROGRESSES.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
AS BEEN THE CASE THIS SUMMER...SHOWERS FORM ALMOST EVERY DAY.
CURRENT ACTIVITY IS NOW MAINLY EAST OF INTERSTATE 99...WITH
A FEW HEAVY DOWNPOURS AND A RUMBLE OF THUNDER. ALSO ACROSS
THE SOUTHERN AREAS IS SOME FOG AND LOWER CIGS. STILL MAINLY
CLEAR TO THE NORTH. EXPECT LITTLE CHANGE BEFORE MID MORNING.
AFTER MID MORNING...EXPECT MAINLY VFR CONDITIONS. THERE WILL
STILL BE A CHC OF SHOWERS AND PERHAPS A FEW THUNDERTORMS
ACROSS THE SOUTH THIS AFT AND EVENING.
AT THE SAME TIME...SOME SHOWERS AND STORMS COULD FORM
ACROSS NORTHERN PA LATER TODAY. OVERALL A COMPLEX PATTERN.
STRONG COLD FRONT TO MOVE ACROSS THE REGION LATE TUESDAY.
EXPECT BANDS OF SHOWERS AND THUNDERSTORMS TO FORM. DYNAMICS
LAG THE FRONT SOME...BUT STILL SOME CONCERN FOR STRONG WINDS
WITH ANY STORMS.
WINDY ON WED...AS COLDER AIR WORKS SOUTHWARD.
LOOKING AT DRY CONDITIONS AFT WED.
OUTLOOK...
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS.
WED-FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...ROSS
SHORT TERM...ROSS
LONG TERM...ROSS/DEVOIR
AVIATION...MARTIN/RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
200 AM EDT MON AUG 12 2013
.SYNOPSIS...
LOOK FOR A MILD AND INCREASINGLY HUMID DAY TODAY ACROSS THE
REGION...AHEAD OF THE ARRIVAL OF A STRONG COLD FRONT PASSAGE ON
TUESDAY. THERE WILL BE A COUPLE WEAK WEATHER DISTURBANCES MOVING
ACROSS THE AREA WHICH COULD TOUCH OFF BRIEF SHOWERS AND
THUNDERSTORMS TODAY...BUT MOST OF THE AREA WILL BE FREE OF
SIGNIFICANT RAINFALL. BEHIND THE COLD FRONT ON TUESDAY...ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TODAY/...
TRACKING SEVERAL AREAS OF CONVECTION MOVING ACROSS SOUTHERN ZONES
EARLY THIS MORNING. STORMS ARE PUTTING DOWN SOME HEAVY DOWNPOURS
BUT FORTUNATELY THEY ARE MOVING FAST ENOUGH TO PREVENT SIGNIFICANT
ACCUMULATIONS. LOOKING AT LATEST RUC AND HRRR RUNS SHOWS MOST OF
THE CONVECTION TAPERING OFF FOR ALL BUT THE EXTREME SW CORNER OF
THE CWA WHERE SHOWERS WILL LIKELY PERSIST UNTIL AFTER SUNRISE.
AFTER LOW CLOUDS DIMINISH THIS MORNING THE REGION WILL SEE
VARIABLE CLOUDS WITH A SLIGHT CHANCE OF SHOWERS OR
THUNDERSHOWERS...WITH THE HIGHEST CHANCES OVER THE NW AND SE
PORTIONS OF THE CWA...BUT SIMILAR TO SUNDAY...MOST OF THE REGION WILL
MISS OUT ON ANY SIGNIFICANT RAINFALL. TEMPERATURES WILL BE CLOSE TO
AVERAGE...THOUGH IT WILL BE MORE HUMID AHEAD OF THE APPROACHING
FRONT ARRIVING ON TUESDAY.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM TUESDAY/...
THE STRONG FRONTAL SYSTEM WILL BECOME AN ISSUE OVERNIGHT MONDAY
INTO TUESDAY. FRONTAL TIMING SUGGESTS CHANCE RAIN AND THUNDER
COMES UP AFTER MIDNIGHT IN WESTERN AREAS AND STROLLS EASTWARD WITH
TIME DURING OVERNIGHT INTO TUESDAY MORNING. IF THE FRONT SPEEDS UP
TUESDAY AFTERNOON COULD TURN OUT OKAY. TRIED TO SHOW POPS LOWERING
IN THE SECOND HALF OF AFTERNOON WEST TO EAST.
ALWAYS A POP PROBLEMS AS SREF HAS THE PATTERN OF DECREASED POPS
BUT IT IS SO WET BIASED ONE CANNOT USE IT EFFECTIVELY IN GRIDS.
THE GEFS SHOWS LOWER POPS AFTER 18Z TUESDAY AS DO ALL THE
MODELS...NAM/GFS. SUSPECT PW TELLS US TWO IMPORTANT THINGS 1) NOT
GOING TO BE A BIG RAIN EVENT AND 2) PW DROPS IN AFTERNOON IMPLYING
THE AFTERNOON COULD BE RAIN FREE IN WEST. POPS REFLECT THIS
THINKING AS BEST AS PRACTICABLE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
GENERALLY COSMETIC CHANGES MADE TO PREVIOUS EXTENDED FORECAST
TODAY AS PATTERN WILL BE DOMINATED BY THE ROCKY MOUNTAIN UPPER
RIDGE AND DOWNSTREAM LONG WAVE TROF FROM EASTERN CANADA TO THE MID
ATLANTIC REGION THIS WEEK.
BEST CHANCE OF PRECIPITATION WILL COME FROM A FRONTAL SYSTEM
MONDAY NIGHT AND TUESDAY BEFORE THE MEAN UPPER TROF AXIS SETTLES
EAST OF THE AREA FOR THE LATTER HALF OF THIS WEEK. AS PREVIOUSLY
MENTIONED...THE BIGGEST IMPACT WILL BE A FRESH SHOT OF DRIER AND
COOLER AIR FOR THE MIDDLE OF THE WEEK AS TEMPERATURES DROP BELOW
AVERAGE ON WED AND THU. FLOW BEGINS TO TURN SW LATE IN THE PERIOD
FOR SOME MODERATION AS THE WEEKEND APPROACHES.
LATE IN THE PERIOD...WESTERN ATLANTIC UPPER RIDGE RETROGRADES AND
AMPLIFIES OVER BERMUDA. THIS WILL HELP TO SHARPEN THE EAST COAST
TROF AXIS AND DIRECT DEEPER LAYER MOISTURE NORTHWARD INTO THE MID
ATLANTIC REGION NEXT WEEKEND. HAVE INTRODUCED SHOWER CHANCES AS A
RESULT...MAINLY ON SUNDAY. GULF COAST TROPICAL DEVELOPMENT IS
POSSIBLE WITH THIS SURGE OF MOISTURE...SO WE`LL BE WATCHING THIS
WITH INTEREST AS THE WEEK PROGRESSES.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
PRIMARILY VFR CONDITIONS PREVAIL ACROSS CENTRAL PA THIS
EVENING...WITH ISOLATED SHOWERS AND A RARE TSTM DRIFTING W-E
ALONG THE PA TURNPIKE BRINGING SHORT-LIVED REDUCTIONS. THESE
SHOULD DIMINISH DURING THE EARLY MORNING HOURS.
PATCHY MAINLY MVFR FOG /ISO IFR/ WILL DEVELOP BETWEEN 06Z-09Z AND
DISSOLVE THROUGH MID MORNING. CHC OF LOWER STRATOCU ACROSS SE
LATE.
FOR MONDAY...PRIMARILY VFR CONDITIONS CONTINUE. CANNOT RULE OUT
STRAY SHOWERS AND/OR ISOLATED THUNDERSTORMS...BUT MAJORITY OF THE
DAY WILL BE DRY IN ANY ONE LOCATION. MODELS HINTING AT HIGHER POPS
IN THE SE DURING SECOND HALF OF AFTERNOON BASED ON INCREASING
INSTABILITY AND HINTS OF QPF IN JUST ABOUT ALL MODELS.
A STRONG FRONTAL SYSTEM SLIDES IN FROM THE NW OVERNIGHT MONDAY
INTO TUESDAY...WITH CONDITIONS DETERIORATING. AREA OF RAIN AND SCT
THUNDER WORKS IN FROM THE NW MON NIGHT...EXITING SE BY TUE AFT.
OUTLOOK...
MON...PRIMARILY VFR. ISO SHRA/TSTM...HIGHEST CHANCE IN SE LATE AFT.
MON NIGHT...DETERIORATING CONDITIONS FROM NW. SHOWERS/TSTMS LKLY
MAINLY OVER THE NW AIRFIELDS. MAINLY VFR SE.
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS...ESP BEFORE NOON.
WED-FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...ROSS
SHORT TERM...ROSS
LONG TERM...ROSS/DEVOIR
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
424 AM CDT MON AUG 12 2013
.DISCUSSION...
TROPICAL AIRMASS OVER SE TX HAS BEEN RESPONSIBLE FOR MAINLY SCT
SHOWERS AND THUNDERSTORMS. DAY TIME HEATING HAS INCREASED
INSTABILITY OVER NORTHERN PORTIONS OF SE TX RESULTING IN STRONG TO
ALMOST SEVERE STORMS WITH SMALL HAIL AND LOCALIZED HEAVY RAINFALL.
NOT AS OPTIMISTIC WITH RAIN CHANCES TODAY FOR A COUPLE OF REASONS.
FIRST 00Z 500MB ANALYSIS HAS UPPER LEVEL RIDGE AND HEIGHT RISES
OVER THE AREA. LOOKS LIKE TWO RIDGE CENTERS ARE TAKING SHAPE OVER
N TX AND BERMUDA RIDGE EDGING IN ACROSS FLORIDA. MODELS ARE
PRETTY CONSISTENT WITH KEEPING A FLAT RIDGE OVER MUCH OF TX AND N
GULF COAST. WATER VAPOR IMAGERY SHOWS UPPER LEVEL LOW NOW OVER
MEXICO SOUTH OF RIO GRANDE. THINK THIS WILL BE TOO FAR WAY AND TOO
WEAK TO IMPACT SE TX. GOES SOUNDER PRECIP WATER IMAGERY SHOWS
ABOUT 1.9-2 INCH PRECIP WATER OVER THE REGION BUT THE TREND HAS
BEEN THAT OF DRYING. LATEST HRRR AND 00Z WRF-ARW ALONG WITH
NAM/GFS REALLY ALL POINT TO BEST COVERAGE OF CONVECTION OVER E TX
AND SW LA. DECIDED TO KEEP AT LEAST SOME 30 POPS FOR EASTERN PARTS
OF THE FORECAST AREA BASED ON THESE TRENDS WITH 20 POPS ELSEWHERE.
IT WILL TAKE A WHILE TO REACH THE LOW 90S FOR CONVECTION TO START
TO REALLY INITIATE. COULD TAKE MORE HEATING IF MOISTURE CONTINUES
TO DECREASE. STILL WILL NEED TO WATCH FOR STRONG STORMS THAT
APPROACH SEVERE LEVELS ESPECIALLY WHERE THERE IS MAXIMUM HEATING
AND INSTABILITY. POTENTIAL STILL EXISTS FOR LOCALIZED HEAVY RAIN
WITH THE STRONGER STORMS.
TUE THROUGH THUR UPPER LEVEL RIDGE BUILDS OVER TX AND MOVES BACK
OVER S ROCKIES/GREAT BASIN BY THURSDAY. THIS RESULTS IN NW FLOW
ALOFT OVER THE REGION WITH A BROAD TROUGH OVER THE GREAT LAKES.
LOOKS LIKE BOTH THE GFS/ECMWF ARE TRYING TO DEEPEN THE TROUGH OVER
THE MISS RIVER VALLEY LATE FRI THROUGH SATURDAY. THE PATTERN
SUPPORTS A FRONTAL BOUNDARY PUSHING INTO SE TX LATE WED THROUGH
THUR. FRONT MAY PUSH TO THE COAST ON FRI BEFORE STALLING. FRONT
SHOULD BE A FOCUS FOR THUNDERSTORM ACTIVITY SO MAY HAVE A MORE WET
PATTERN DEVELOP FOR THE END OF THE WEEK. TIMING OF THE FRONT WILL
BE THE MAIN CHALLENGE WITH THE FORECAST. THINK A SLOWER FRONTAL
PUSH LIKE THE GFS MAY BE THE BEST SOLUTION RIGHT NOW. GIVEN THAT
UPPER LEVEL FLOW BECOMES MORE AMPLIFIED THUR/FRI...THINK FRONT
WILL TAKE ITS TIME GETTING INTO SE TX. FOR NOW WILL KEEP 20/3O
POPS FOR THE AREA MAINLY DUE TO UNCERTAINTY SURROUNDING THE TIMING
OF THE FRONT.
DRIER BOUNDARY LAYER AIR SHOULD REACH SE TX FRI INTO SAT SO THINK
RAIN CHANCES WILL DROP OFF FOR NEXT WEEKEND. UPPER LEVEL TROUGH
AXIS LOOKS TO PUSH BY ON SATURDAY PER GFS WHILE THE ECMWF HOLD THE
TROUGH MORE TO THE WEST OF THE GFS AND DOES NOT DISSIPATE THE
FRONT AS QUICKLY. MAY NEED TO HOLD ONTO SOME POPS FOR THE WEEKEND
BUT THINK DRIER BOUNDARY LAYER WILL LIMIT PRECIP. THE UPPER LEVEL
TROUGH DOES LIFT OFF TO THE NE LATE IN THE WEEKEND SO THINK A
DRIER FORECAST FOR PRECIP LOOKS REASONABLE.
LASTLY THE GFS IS TRYING TO DEVELOP A TROPICAL LOW PRESSURE IN
THE NW CARIB ON THUR AND MOVES IT INTO INTO THE GULF FRI/SAT.
GIVEN UPPER LEVEL PATTERN THAT DEVELOPS OVER THE N GULF FOR THE
WEEKEND...SHOULD ANYTHING DEVELOP TROPICALLY IT WILL BE IN A
HIGHLY SHEARED ENVIRONMENT. UPPER LEVEL TROUGH WILL ALSO LIKELY
TAKE THE SYSTEM WELL EAST OF THE AREA TOWARDS FL PANHANDLE ON
SUNDAY. THIS WILL BE SOMETHING TO KEEP AN EYE ON BUT OVERALL NOT
MUCH OF A CONCERN.
39
&&
.MARINE...
A FEW ISOLATED SHOWERS ACROSS THE COASTAL WATERS THIS MORNING BUT
COVERAGE WILL BE MUCH LESS TODAY THAN OVER THE WEEKEND. A
RELATIVELY FLAT PRESSURE GRADIENT ACROSS THE COASTAL WATERS WILL
KEEP LIGHT ONSHORE WINDS IN PLACE THROUGH THE MIDDLE OF THE WEEK.
A WEAK FRONT WILL APPROACH THE COAST LATE IN THE WEEK LEADING TO A
BRIEF PERIOD OF OFFSHORE WINDS. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 99 77 99 77 99 / 20 10 10 10 20
HOUSTON (IAH) 95 77 97 77 96 / 30 10 10 10 20
GALVESTON (GLS) 92 81 93 81 92 / 30 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...39
AVIATION/MARINE...38
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1142 PM CDT SUN AUG 11 2013
.UPDATE...
ISSUED AT 934 PM CDT SUN AUG 11 2013
WORKING ON AN UPDATE TO THE DENSE FOG ADVISORY TO INCLUDE CLARK
COUNTY AND WILL ALSO BUMP UP THE START TIME. UPPING THE START TIME
SINCE DENSE FOG IS QUICKLY FORMING IN CENTRAL WISCONSIN WITH SKIES
CLEARING. UPDATE COMING OUT SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 248 PM CDT SUN AUG 11 2013
MAIN FORECAST CONCERNS ARE ON PRECIPITATION TONIGHT AND DENSE FOG
POTENTIAL TONIGHT INTO MONDAY MORNING.
CURRENTLY...
WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER
MUCH OF THE U.S. AND CANADIAN ROCKIES...WHILE TROUGHING DOMINATED
SOUTHEAST CANADA. THE FORECAST AREA RESIDES IN WEST-NORTHWEST
FLOW...WITH SHORTWAVES OF NOTE OVER NORTHEAST IOWA...SOUTHERN
MANITOBA AND A MUCH STRONGER ONE OVER NORTHERN MANITOBA. THE
NORTHEAST IOWA SHORTWAVE...COMBINED WITH A LOW TO MID LEVEL
FRONTOGENESIS ZONE AND A RIGHT ENTRANCE REGION OF AN 80 KT UPPER
JET STREAK IN NORTHERN WI...HAS HELPED TO KEEP SOME SHOWER
ACTIVITY GOING ACROSS NORTHERN IOWA THROUGH THE AFTERNOON. ALSO
PLENTY OF CLOUDS EXIST ACROSS THE FORECAST AREA...RESULTING FROM
DEEP LOW LEVEL MOISTURE SEEN ON THE 12Z MPX SOUNDING AND THE LACK
OF MUCH WIND FLOW TO ADVECT DRIER AIR SEEN ACROSS NORTH DAKOTA AND
NORTHERN MN. THE DRIER AIR LIES BEHIND A SURFACE TROUGH STRETCHING
FROM EASTERN NEBRASKA INTO NORTHWEST WI. A FEW SHOWERS HAVE FORMED
ON THIS TROUGH ACROSS EAST CENTRAL MN. FARTHER SOUTH...A WARM
FRONT ENHANCED BY OUTFLOW FROM THE SHOWERS WAS PRESENT STRETCHING
ALONG US-20 IN IOWA.
SYNOPTIC OVERVIEW...
FOCUS IS MOSTLY ON THE SHORTWAVE OVER NORTHERN MANITOBA. MODELS PROG
THIS SHORTWAVE TO DROP SOUTHEAST INTO UPPER MICHIGAN ON MONDAY. THIS
SHORTWAVE ALLOWS UPPER TROUGHING TO MOVE INTO THE FORECAST AREA...
AND SIMULTANEOUSLY HELPS GIVE THE SURFACE TROUGH IN MN A PUSH
SOUTHEAST. BY 12Z MONDAY...THE TROUGH...LIKELY NOW A COLD
FRONT...SHOULD BE SOUTHEAST OF THE AREA. THERE ARE ALSO
INDICATIONS OF AN INVERTED SURFACE TROUGH LINGERING BACK EXTENDING
NORTHWEST TO SOUTHEAST OVER CENTRAL/EASTERN WI...ASSOCIATED WITH
THAT SHORTWAVE DROPPING INTO UPPER MI.
HAZARDS...
DENSE FOG CONCERNS TONIGHT GIVEN RECENT RAINS...LIGHT WINDS...LATE
DAY CLEARING AND SMALL TEMP/DEW POINT SPREADS ALREADY.
DETAILS...
SHOWERS IN EAST CENTRAL MINNESOTA MAY TRY TO DROP DOWN INTO
NORTHWESTERN SECTIONS OF THE FORECAST AREA THIS EVENING.
HOWEVER...THEY ARE HIGHLY DIURNALLY DRIVEN...THUS ONCE HEATING
ENDS THEY SHOULD FALL APART QUICKLY. INCLUDED SOME 20 PERCENT
CHANCES FOR THEM FOR A FEW HOURS THIS EVENING. MEANWHILE...TO THE
SOUTH...ONGOING SHOWERS AND STORMS ACROSS NORTHEAST IOWA MAY
PERSIST THROUGH MUCH OF THE EVENING...SUPPORTED BY THE SHORTWAVE
TRACKING ACROSS NORTHEAST IOWA...THE LOW/MID LEVEL F-GEN AND RIGHT
ENTRANCE REGION. HOWEVER...AS THE UPPER FLOW TURNS MORE
NORTHWESTERLY... ANTICIPATING THESE FORCING FEATURES TO DROP
SOUTHEAST AND HELP DIMINISH THE PRECIPITATION. DID KEEP 20-40
PERCENT CHANCES GOING AFTER MIDNIGHT JUST IN CASE PRECIP HOLDS
ON A BIT LONGER THAN EXPECTED.
CONCERN THEN SHIFTS TO FOG GIVEN RECENT RAIN. CLOUDS OVER THE
FORECAST AREA...PARTICULARLY OVER THE NORTHERN HALF...SHOULD CLEAR
OUT THIS EVENING. WINDS LOOK TO STAY FAIRLY LIGHT THROUGH THE
NIGHT...EVEN AFTER THE TROUGH/FRONTAL PASSAGE. ITS WORTH NOTING
THAT WINDS DO PICK UP AT 950MB INTO THE 10-20 KT RANGE BY 12Z...
HOWEVER...THESE ARE ABOVE A 3C FRONTAL INVERSION. THUS...THEY SHOULD
NOT IMPACT THE FOG POTENTIAL MUCH. IN FACT...11.00Z/06Z/12Z HIRES
ARW/NMM AND 11.09Z SREF VISIBILITY PROGS SHOW PRETTY MUCH A SOLID
AREA OF FOG OVER SOUTHEAST MN...NORTHERN PARTS OF IOWA AND MUCH OF
SOUTHERN WI. ADDED MENTION OF FOG EARLIER ACROSS MUCH OF THE
FORECAST AREA...AND NOW HAVE RAISED THE COVERAGE TO WIDESPREAD IN A
CORRIDOR FROM SOUTHEAST MINNESOTA EAST INTO JACKSON...JUNEAU...ADAMS
AND VERNON COUNTIES OF WI. THIS AREA HAS ALSO BEEN INCLUDED IN A
DENSE FOG ADVISORY...SINCE FROM A REGIONAL PERSPECTIVE SEEMS TO
HAVE THE HIGHEST PROBABILITY OF METEOROLOGICAL CONDITIONS
FAVORABLE FOR DENSE FOG. THE ADVISORY MAY HAVE TO BE EXPANDED
SOUTH...ESPECIALLY IF SKIES END UP CLEARING THERE.
FOR MONDAY...COOLER AIR ALOFT UNDER THE UPPER TROUGHING COMBINED
WITH THE INVERTED SURFACE TROUGH...DAYTIME HEATING AND LINGERING LOW
LEVEL MOISTURE SHOULD ALLOW FOR ISOLATED/SCATTERED SHOWERS TO FORM
ALONG/NORTHEAST OF I-94. MLCAPE VALUES ALONG THE INVERTED TROUGH ARE
IN THE 100-300 J/KG AT 18Z...ENOUGH MAYBE TO GET A FEW
THUNDERSTORMS. BETTER INSTABILITY IS OFF TOWARDS SOUTHEAST WI WITH
HELP FROM LAKE BREEZE CONVERGENCE. ONCE THE FOG AND ASSOCIATED LOW
STRATUS MIX OUT A FEW HOURS AFTER SUNRISE...RELATIVELY BREEZY
NORTHWEST WINDS APPEAR TO SET UP. 850MB TEMPS IN THE 10-14C RANGE
SUPPORT HIGHS IN THE MID 70S TO LOW 80S.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 248 PM CDT SUN AUG 11 2013
MUCH OF THE ENTIRE LONG TERM PERIOD IS DOMINATED BY RIDGING OVER THE
WESTERN U.S. AND TROUGHING IN THE EASTERN U.S....A POSITIVE PNA
PATTERN THAT RESULTS IN COOLER AND DRIER THAN NORMAL WEATHER. AT THE
SURFACE...CANADIAN HIGH PRESSURE IS PROGGED TO BUILD INTO THE AREA
MONDAY NIGHT AND TUESDAY...SIT OVER THE AREA TUESDAY NIGHT THROUGH
WEDNESDAY...THEN ONLY SLOWLY DRIFT OFF TOWARDS THE EASTERN GREAT
LAKES THIS WEEKEND. DRY AIR ACCOMPANYING THE HIGH LOOKS TO KEEP THE
BULK OF THE LONG TERM PERIOD DRY. IN FACT...PRECIPITABLE WATER
VALUES ARE FORECAST BETWEEN 50-70 PERCENT OF NORMAL FOR TUESDAY
THROUGH THURSDAY. THIS SHOULD RESULT IN DECENT MIXING OF DEW POINTS
DURING THE AFTERNOONS.
THE ONLY FEATURE REALLY OF INTEREST FOR POTENTIAL PRECIPITATION IS A
SHORTWAVE TROUGH THAT DROPS DOWN THROUGH THE NORTHWEST FLOW INTO THE
AREA THURSDAY NIGHT AND FRIDAY. BOTH THE 11.12Z GFS/CANADIAN PRODUCE
SOME LIGHT PRECIPITATION WITH IT OVER WESTERN AND NORTHERN SECTIONS
OF THE FORECAST AREA...WHEREAS THE 11.00Z/11.12Z ECMWF IS DRY. FROM
A CONSENSUS STANDPOINT...HAVE CONTINUED TO CARRY A 20 PERCENT CHANCE
TO ACCOUNT FOR THE GFS/CANADIAN. HOWEVER...LATER FORECASTS WILL BE
ABLE TO GO DRY IF THE GFS/CANADIAN TREND TOWARDS THE ECMWF.
TEMPERATURE WISE...850MB TEMP ANOMALIES ARE PROGGED TO BOTTOM OUT
BETWEEN 1-1.5C BELOW NORMAL FOR TUESDAY AND WEDNESDAY...READINGS OF
8C EAST TO 10C WEST. THUS THIS WILL BE THE COLDEST PERIOD WITH HIGHS
IN THE 70S. LOWS ARE LIKELY GOING TO DIP INTO THE 40S AT THE TYPICAL
COLD SPOTS TUESDAY NIGHT AND WEDNESDAY NIGHT WITH THE HIGH
OVERHEAD...WHICH WILL ALSO BE THE MOST FAVORABLE TIME PERIODS FOR
VALLEY FOG. VALLEY FOG IS ALSO POSSIBLE MONDAY NIGHT...BUT WINDS
WITH THE INCOMING HIGH MAY RESTRICT SOME OF THE COVERAGE. SLOW
WARMING OF 850MB TEMPS AND ANOMALIES IS FORECAST FOR THURSDAY AND
BEYOND...PEAKING AT 12C EAST TO 15C WEST AND AROUND NORMAL FOR
ANOMALY BY SUNDAY. THUS TEMPERATURES SHOULD SLOWLY CLIMB TOO EACH
DAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1142 PM CDT SUN AUG 11 2013
WITH SKIES CLEARING OUT...DENSE FOG HAS QUICKLY FORMED ACROSS MUCH
OF THE REGION. RST HAS ALREADY DROPPED TO 1/4SM AND EXPECT THAT
LSE WILL FOLLOW SUIT SHORTLY. SKY COVER IS THE ONLY THING HOLDING
BACK THE FOG FROM BECOMING MORE WIDESPREAD AS THE UPPER LEVEL
PATTERN HAS SOMEWHAT STALLED. FROM TAKING A LOOK DOWN INTO THE
VALLEY FROM THE OFFICE WHICH IS UP IN THE BLUFFS...THERE IS A
STRATUS LAYER DEVELOPING IN THE RIVER CHANNEL. SO...EXPECT THAT
CONDITIONS WILL CONTINUE TO DROP...JUST PERHAPS A LITTLE SLOWLY
SICNE THE UPPER LEVEL CLOUD COVER IS IN PLACE. CONDITIONS WILL
RAPIDLY IMPROVE TOMORROW MORNING AS DRIER AIR MOVES IN AND THE
SKIES CLEAR OUT. CONDITIONS MAY BE FAVORABLE FOR VALLEY FOG AGAIN
MONDAY NIGHT INTO TUESDAY MORNING...BUT IT SHOULD STAY VFR THROUGH
6Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT MONDAY FOR WIZ029-032>034-
041>044-053.
MN...DENSE FOG ADVISORY UNTIL 9 AM CDT MONDAY FOR MNZ079-086>088-
094>096.
IA...NONE.
&&
$$
UPDATE...HALBACH
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1154 AM MDT MON AUG 12 2013
.UPDATE...
&&
.SHORT TERM...ONLY MINOR CHANGES TO THE FORECAST. HEALTHY CROP OF
DIURNAL CONVECTION HAS FORMED OVER THE MOUNTAINS AND SHOULD
PROGRESS SLOWLY EASTWARD. STORM MOTIONS HAVE BEEN SLOW
INITIALLY...BUT SHOULD PICK UP A BIT AS WE WILL LIKELY HAVE AN
ORGANIZED OUTFLOW BOUNDARY HEADED EAST IN A COUPLE OF HOURS. STILL
SOME HEAVY RAIN POTENTIAL...BUT BETWEEN THE LIMITED CAPE OF AROUND
500 J/KG NEAR THE MOUNTAINS AND EXPECTED STORM MOVEMENT I DO NOT
EXPECT MUCH OF A FLOODING THREAT OUTSIDE OF THE BURN AREAS. FOR
THE BURN AREAS...AGAIN STORM STRENGTH AND MOISTURE ARE LIMITED BUT
WE WILL HAVE TO WATCH OUT FOR THE SLOW MOTIONS. MAIN THREAT SHOULD
BE THROUGH ABOUT 4 PM WITH THE STRONGEST ACTIVITY FURTHER EAST
AFTER THAT. I DID TWEAK POPS DOWN ON THE PLAINS FOR THIS AFTERNOON
EXPECTING THAT THE STORMS WILL BE SLOW TO PROGRESS EASTWARD. COULD
BE SOME DEVELOPMENT OUT THERE AS WELL BUT LIMITED UNTIL THIS
EVENING.
&&
.AVIATION...SCATTERED THUNDERSTORMS SHOULD PROGRESS EAST OFF THE
MOUNTAINS ACROSS THE DENVER AREA. ACTIVITY MOST LIKELY BETWEEN 21Z
AND 00Z THOUGH THERE WILL STILL BE SOME AROUND THIS EVENING. MAIN
IMPACT SHOULD BE VARIABLE WINDS GUSTING TO AROUND 30 KNOTS.
&&
.PREV DISCUSSION... /ISSUED 355 AM MDT MON AUG 12 2013/
SHORT TERM...WATER VAPOR LOOP INDICATED A MOISTURE PLUME SHIFTING
NORTHEAST ACROSS COLORADO EARLY THIS MORNING. AT THE SURFACE...A
WEAK SURGE HAD PUSH ACROSS MOST OF THE PLAINS WITH A SLIGHT
INCREASE IN LOW LEVEL MOISTURE. HOWEVER...THIS MOISTURE WAS QUITE
SHALLOW AS PRECIPITABLE WATER VALUES HAD BARELY BUDGED OVER THE
LAST 24 HOURS. OVERALL...THE WEATHER PATTERN REMAINS QUITE SIMILAR
TO YESTERDAY WITH THE UPPER LEVEL RIDGE CENTERED OVER THE STATE.
HOWEVER...ONE FEATURE THAT MAY COME INTO PLAY IS AN UPPER LEVEL
SPEED MAX MOVING ACROSS THE DESERT SOUTHWEST. THE FORECAST AREA
WILL BE IN THE LEFT EXIT REGION OF THIS JET FROM THIS AFTERNOON
THROUGH TONIGHT. THERE WAS DEEP...PERSISTENT...BUT WEAK Q-G LIFT
NOTED IN MOST MODELS THROUGH TONIGHT. THIS SHOULD HELP INCREASE
CONVECTIVE COVERAGE A BIT FROM YESTERDAY. MEANWHILE...SHORT RANGE
MESOSCALE MODELS INCLUDING THE WRF AND HRRR SHOW THE TYPICAL START
TO CONVECTION ALONG THE FRONT RANGE MOUNTAINS AND FOOTHILLS BY
17Z-18Z...AND THEN SPREADING/DEVELOPING EASTWARD THROUGH THE
AFTERNOON HOURS. AT THIS POINT...SEE LITTLE REASON TO ARGUE WITH
THIS SCENARIO. THERE WILL BE A SLIGHT RISK OF ONE OR TWO STORMS
BRIEFLY REACHING SEVERE CRITERIA ON THE PLAINS WITH MARGINAL
HAIL/WIND.
WITH CONTINUED SYNOPTIC SCALE LIFT AND WEAK LOW LEVEL
SOUTHEASTERLY JET OVERNIGHT...WILL KEEP A CHANCE OF STORMS IN THE
FORECAST THROUGH TONIGHT.
LONG TERM...EASTERLY UPSLOPE SURFACE FLOW WILL MOVE OVER THE
PLAINS FROM A SHORTWAVE TROUGH DIVING SOUTH FROM THE DAKOTAS
ALOFT. COMBINE THIS WITH A FEW DISTURBANCES MOVING IN THE
WESTERLY FLOW ALOFT AND INCREASING UPPER AND MID-LEVEL MOISTURE
MOVING IN FROM THE SOUTHWEST WILL ALL COME TOGETHER TUESDAY AND
WEDNESDAY FOR COOLER AND WETTER DAYS. THE FOCUS FOR THE MOST
SIGNIFICANT WEATHER WILL BE EAST OF THE MOUNTAINS AS SLIGHTLY
DRIER AIR WILL BE FILTERING IN FROM THE WEST. STORM MOTIONS ARE
PROGGED TO BE SLOW...10 MPH OR LESS SO THUNDERSTORMS WITH HEAVY
RAINFALL WILL BE A CONCERN. BEST INSTABILITY WILL BE OUT TOWARDS
THE EASTERN STATE BORDER WITH HAIL AND STRONG WINDS THE THREAT.
ALL THE CONDITIONS WILL EXIST THROUGH THE BOTH DAYS TO HAVE AT
LEAST A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS LAST THROUGHOUT
THE NIGHTS. TEMPERATURES WILL BE AS MUCH AS 10 DEGREES COOLER THAN
TODAY WITH READINGS IN THE UPPER 70S TO LOWER 80S FOR THE PLAINS
AND 60S TO 70S FOR THE HIGH COUNTRY.
BEGINNING THURSDAY...THE FLATTENED UPPER RIDGE WILL BEGIN BUILDING
BACK NORTH THROUGH FRIDAY...STRETCHING FROM ARIZONA UP TO
MONTANA. THIS WILL PUT COLORADO UNDER NORTH-NORTHWEST FLOW ALOFT.
THE SHORTWAVE TROUGH MAY STILL HAVE AN AFFECT THURSDAY AND SOUTH
TO SOUTHEASTERLY SURFACE FLOW OVER THE FAR EASTERN PLAINS WILL
TRANSPORT SOME MOISTURE IN FOR SCATTERED STORM ACTIVITY OVER THE
MOUNTAINS AND A SLIGHT CHANCE FOR THE PLAINS. DRIER AIR WILL BE
SPREADING IN FROM THE WEST FRIDAY TO KEEP CHANCES FOR STORMS OVER
THE HIGH TERRAIN WITH ISOLATED COVERAGE. TEMPERATURES WILL BE
CLIMBING BACK TO AVERAGE AND POSSIBLY SLIGHTLY WARMER UNDER THE
BUILDING RIDGE.
ON SATURDAY...A TROUGH WILL MOVE ONSHORE OVER THE WEST COAST AND
START MOVING EAST. SATURDAY WILL BE ONE MORE WARM AND DRY DAY
BEFORE THE TROUGH DRAWS MOISTURE INTO THE AREA FOR SLIGHTLY WETTER
CONDITIONS SUNDAY. WILL HAVE TO FOLLOW THE PROGRESSION OF THE
MODELS FOR THIS TROUGH TO SEE HOW STRONG IT MAY BE. FOR NOW KEPT
TEMPERATURES THE SAME...BUT MAY NEED TO COOL THEM OR LATER
PERIODS.
AVIATION...WEAK SURFACE BOUNDARY THAT BARELY PUSHED THROUGH THE
FRONT RANGE AIRPORTS WILL KEEP LIGHT AND VARIABLE WINDS IN THE
FORECAST THROUGH 15Z-17Z. ONLY A SLIGHT CHANCE OF LIGHT/PATCHY
FOG DEVELOPING 12Z-14Z WITH MARGINAL T/TD SPREADS. THEN NORMAL
DIURNAL EASTERLIES WILL DEVELOP. STORM CHANCES WILL BE A LITTLE
HIGHER THAN YESTERDAY SO TEMPO VRB20G30-35KT WINDS AND TS OR -TSRA
WOULD BE WARRANTED IN THE FAVORED TIME FRAME FROM 20Z- 02Z. A
SLIGHT CHANCE OF STORMS LINGERING PAST 06Z. BRIEF MVFR CONDITIONS
WOULD BE POSSIBLE IF A STORM CORE PASSES OVERHEAD.
HYDROLOGY...PRECIPITABLE WATER VALUES AND TEMP PROFILES ARE
SIMILAR TO THOSE OBSERVED YESTERDAY...ALTHOUGH STORM MOTION WILL
LIKELY BE UNDER 10 MPH. STORMS THIS AFTERNOON AND EVENING WILL BE
CAPABLE OF PRODUCING 0.50 TO 1.0 INCH IN 30 MINUTES. THAT WOULD
POSE A RISK OF SOME FLOODING IF ONE OF THESE STRONGER STORMS MOVES
OVER A FOOTHILL BURN SCAR. THE STRONGEST STORMS ON THE PLAINS
COULD PRODUCE 1-2 INCHES IN AN HOUR WITH MINOR FLOODING. THREATS
ARE LOW ENOUGH AT THIS TIME TO PRECLUDE A FLASH FLOOD WATCH.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....KRIEDERMAN
AVIATION/UPDATE...GIMMESTAD
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1053 AM EDT MON AUG 12 2013
.SYNOPSIS...
WEAKENING HIGH PRESSURE SHIFTS FARTHER OFFSHORE WITH A STALLED
FRONTAL BOUNDARY SOUTH OF THE REGION THROUGH TUESDAY MORNING. A
COLD FRONT MOVES ACROSS LATE TUESDAY. BEHIND THE COLD FRONT...A
LARGE AREA OF HIGH PRESSURE OVER THE MIDWEST WILL BUILD SOUTH AND
EAST ACROSS THE OHIO VALLEY AND MID ATLANTIC STATES THROUGH THE
END OF THE WEEK. THE HIGH IS THEN FORECAST TO REMAIN OVER THE
NORTHEAST NEXT WEEKEND AS A FRONTAL BOUNDARY ALONG THE MID
ATLANTIC COAST LIFTS SLOWLY NORTHWARD.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LATEST WATER VAPOR AND RUC 500 HPA ANALYSIS SHOW A WEAK 500 HPA
SHORTWAVE PASSING JUST TO THE S OF LONG ISLAND...AS THIS EXITS TO
THE EAST BY EARLY AFTERNOON...IT SHOULD BASICALLY BRING THE THREAT
OF SHOWERS TO AN END THROUGH AT LEAST MID AFTERNOON. NOTING THAT
THE AREA OF CONVECTION NEAR LAKE ERIE IS WEAKENING...AND LATEST
GUDIANCE SUGGEST LITTLE IF ANY PRECIPITATION THIS AFTERNOON...HAVE
REDUCED POPS FOR THIS AFTERNOON TO SLIGHT CHANCE...AND HAVE TAKEN
OUT AREAL COVERAGE WORDING...AS THERE IS NOW GREAT DOUBT WHETHER
ANY CONVECTION WILL FORM. IF CURRENT RADAR/SATELLITE/MODEL TRENDS
HOLD...COULD SEE PULLING POPS COMPLETELY WITH MIDDAY UPDATE.
MADE SOME MNOR CHANGES TO THE SKY GRID...BUT STILL APPEAR ON TRACK
TO GO FROM MOSTLY CLOUDY TO AT LESAT PARTLY SUNNY THIS AFTERNOON.
BASED ON LATEST VISIBILE TRENDS WESTERN AREAS MAY END UP MOSTLY
SUNNY - BUT NOT QUITE CONFIDENT ENOUGH IN THAT TO FORECAST AT THIS
TIME...BUT WILL REFELCT IN MIDDAY UPDATE IF TRENDS HOLD.
FOR MAX TEMPS TODAY...CONTINUED WITH BLEND OF MAV AND MET GUIDANCE.
THIS YIELDS HIGHS IN THE MOSTLY IN THE LOWER 80S...EXCEPT MID 70S
TO AROUND 80 COASTAL AREAS AND MID 80S IN THE NYC METRO HEAT
ISLAND AREA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
A STEADY PERSISTENT PATTERN DEVELOPS GOING INTO TUESDAY WITH A
STALLED FRONTAL BOUNDARY TO THE SOUTH BUT WITH PERIODIC EPISODES
OF WARM AIR ADVECTION ALOFT AHEAD OF IT. THESE WILL BE ASSOCIATED
WITH SMALL AMPLITUDE SHORTWAVE...WHICH WILL ALSO BRING SOME
POSITIVE VORTICITY ADVECTION. ALL IN ALL...THIS IS POINTING TO AN
UNSETTLED WEATHER SCENARIO THAT WILL CONVEY SHOWERS AND
THUNDERSTORMS POPPING UP AND DEVELOPING NEAR AND WITHIN THE AREA.
FOR THE LOWS TONIGHT...USED A BLEND OF THE WARMER NAM12/MET
GUIDANCE TAKING INTO ACCOUNT THE EXTRA CLOUDS. COLD POOL CONTINUES
TO STRENGTHEN TONIGHT GOING INTO TUESDAY MORNING.
THIS WILL SET UP A HIGHER COVERAGE OF CONVECTION ON TUESDAY WITH
CAPE VALUES ALSO REACHING AROUND THE 1000-1500 J/KG
RANGE...HIGHEST ACROSS THE INTERIOR AWAY FROM THE ONSHORE MARINE
INFLUENCE. SOME THUNDERSTORMS COULD PRODUCE GUSTY WINDS AND HAIL
AS BULK SHEAR 0-6 KM OF MAINLY 30-35 KT WILL BE PRESENT. RIGHT
REAR QUAD JET WILL ALSO BE NEAR THE REGION AS WELL TO HELP WITH
FORCING. THIS WILL ALSO CONVEY THE HIGHEST LOW LEVEL CAPE IN
COMBINATION WITH DEEPEST COLD POOL ALOFT WITH STRONGER CYCLONIC
FLOW ALOFT.
FOR THE HIGHS TUESDAY...USED A BLEND OF MAV AND MET NUMBERS WITH
GREATER WEIGHT TOWARDS THE MAVS WHICH WERE WARMER. THE CONVECTION
IS NOT THOUGHT TO LAST THE WHOLE DAY AND WITH THE BREAKS...ENOUGH
DAYTIME WARMING IS EXPECTED TO GIVE SLIGHTLY WARMER TEMPERATURES.
THE COLD FRONT APPROACHES DURING THE DAY AND THEN MOVES ACROSS
DURING THE EVENING. CONVECTION WILL LOWER IN COVERAGE BY LATE
EVENING WITH MAINLY DRY CONDITIONS RETURNING FROM WEST TO EAST
OVERNIGHT ON A MORE NORTHERLY FLOW. AGAIN...GIVEN EXTRA
CLOUDS...WARMER MAV GUIDANCE WAS PREFERRED WITH GREATER WEIGHT FOR
TUESDAY NIGHT LOW TEMPS.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
GLOBAL MODELS ARE ALL IN VERY GOOD AGREEMENT WITH TAKING THE
NORTHERN BRANCH UPPER TROF ACROSS EASTERN CANADA AND THE NE STATES
NORTH AND EAST THROUGH THE END OF THE WEEK...WITH GRADUALLY RISING
HEIGHTS. THE SOUTHERN BRANCH TROF GETS LEFT BEHIND E OF THE MS RIVER
VALLEY. THE LATTER OF WHICH ALSO SLOWLY FILLS AND LIFTS NORTH AND
EAST OVER THE WEEKEND.
AT THE SURFACE...A LARGE SPRAWLING HIGH OVER THE UPPER MIDWEST ON
WED BUILDS EAST ACROSS THE OHIO VALLEY AND MID ATLANTIC STATES
THROUGH THE END OF THE WEEK. A STALLED OUT FRONTAL BOUNDARY ALONG
THE SE AND MID ATLANTIC COAST BEGINS TO SLOWLY LIFT NORTHWARD
THROUGH THE WEEKEND...AS HIGH PRESSURE BUILDS EAST ACROSS NEW
ENGLAND. THUS...AT THIS TIME...THE FORECAST IS MAINLY DRY WITH A LOW
CHANCE FOR SHOWERS NEXT WEEKEND DUE TO THE OFFSHORE FRONTAL BOUNDARY
APPROACHING FROM THE SOUTH. THE 00Z GFS AND ECMWF BOTH SUPPORT A DRY
FORECAST NEXT WEEKEND. NEED TO SEE SOME MORE RUN TO RUN CONSISTENCY
BEFORE REMOVING RAIN CHANCES COMPLETELY.
IN ADDITION...THE AIR MASS WILL BE COOLER THAN NORMAL BY ABOUT 3 TO 5
DEGREES. HIGHS ARE FORECAST TO BE IN THE UPPER 70S TO AROUND
80...WITH LOWS GRADUALLY MODERATING FROM THE 50S WED MORNING. DEW
POINTS WILL BE MAINLY IN THE 50S.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
GENERALLY VFR CONDITIONS TODAY.
LIGHT SHOWERS WILL PUSH EAST...EXITING THE AREA BY 18Z. EXPECTING
MAINLY DRY CONDITIONS THIS AFTERNOON THOUGH CANNOT RULE OUT A STRAY
LATE AFTN SHOWER. NOT ENOUGH CONFIDENCE AT THIS TIME TO INCLUDE IN TAFS.
SCT-BKN MID AND HIGH LEVEL CLOUDS WILL SCATTER OUT BY LATER THIS
AFTN.
LIGHT AND VARIABLE WINDS WILL TURN SOUTHERLY FOR THE AFTN. PLEASE
SEE COMMENTS CONCERNING SEA BREEZE DEVELOPMENT.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: SEA BREEZE DEVELOPMENT COULD BE +/- 1 HOUR.
KLGA FCSTER COMMENTS: LOW CONFIDENCE ON SEA BREEZE DEVELOPMENT AND
TIMING. COULD BE +1 HR.
KEWR FCSTER COMMENTS: LOW CONFIDENCE ON WIND DIRECTION THROUGH
20Z.
THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH
IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD.
KTEB FCSTER COMMENTS: LOW CONFIDENCE ON WIND DIRECTION THROUGH
20Z.
KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED.
KISP FCSTER COMMENTS: SEA BREEZE TIMING COULD BE +/- 1 HOUR.
.OUTLOOK FOR 12Z TUE THROUGH THU...
.TUE...SCT SHOWERS/TSTMS WITH BRIEF MVFR OR LOWER CONDS.
.WED-FRI...VFR.
&&
.MARINE...
MINOR CHANGES THIS UPDATE TO REFELCT THE LATEST TRENDS IN
OBSERVATIONS AND GUIDANCE. CHANCE FOR ANY CONVECTION THIS
AFTERNOON IS DIMINISHING.
TRANQUIL CONDITIONS WITH A WEAK PRESSURE GRADIENT IN PLACE ACROSS
THE WATERS THROUGH TUESDAY NIGHT. GUSTS WILL REACH UP TO NEAR 20
KT TUESDAY AFTERNOON AND NIGHT SURROUNDING NEAR THE TIMES OF THE
FRONTAL PASSAGE. SCA GUSTS WILL BE POSSIBLE POST COLD FRONT GOING
INTO WEDNESDAY MORNING BUT FORECAST IS BELOW THIS CRITERION AT THE
MOMENT.
A POST-FRONTAL NW FLOW ON WED WILL FEATURE WIND GUSTS RIGHT AROUND
20 KT...WITH SEAS WELL BELOW 5 FT. HIGH PRESSURE THEN BUILDS ACROSS
THE WATERS THU AND FRI WITH WINDS 10 KT OR LESS AND LIGHT SEAS.
&&
.HYDROLOGY...
ISOLD-SCT SHRA/TSRA THROUGH TONIGHT IS EXPECTED TO PRODUCE MAINLY
RAIN AMOUNTS OF BELOW A QUARTER OF AN INCH.
GENERALLY EXPECT BETWEEN MAINLY 4/10 AND 1 INCH OF BASIN AVG QPF
WITH THE COLD FRONT TUE/TUE NIGHT WITH POSSIBLY HIGHER AMOUNTS. ANY
FLOOD POTENTIAL LOOKS TO BE RESTRICTED TO MAINLY POOR DRAINAGE
AND OTHER MINOR FLOODING.
DRY WEATHER THEN PREVAILS THROUGH THE END OF THE WORK WEEK.
&&
.EQUIPMENT...
THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY
IS OFF THE AIR...AND UNAVAILABLE UNTIL FURTHER NOTICE.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JM
NEAR TERM...MALOIT/JM
SHORT TERM...JM
LONG TERM...DW
AVIATION...SEARS
MARINE...MALOIT/JM/DW
HYDROLOGY...JM/DW
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1000 AM EDT Mon Aug 12 2013
.UPDATE...
Per discussion below, a hot day with only isolated showers and
thunderstorms this afternoon. This morning`s KTAE sounding shows
PWAT down to 1.59". With the increased insolation and the stacked
high pressure overhead, temps will max out in the upper 90s inland
areas with a few locations possibly reaching the century mark. Heat
indices will be around 105 and possibly briefly peak at 108 in and
around Valdosta and the Suwannee River Valley.
&&
.PREVIOUS DISCUSSION...
329 AM EDT Mon Aug 12 2013
.NEAR TERM [Today and Tonight]...
With a firmly established upper level ridge in place for one more
day and PWATS expected to continue to drop as deep layer drier air
advects in from the east, conditions appear favorable for what
should be the hottest day of the summer season thus far! For
example, we are forecasting a High temp of 101 at VLD today (which
would eclipse the earlier 100 from June 12), 99 at TLH (which would
exceed the 98 on June 12 and 13, and a 99 at ABY (which would be a
whopping 4 degrees higher than the 95 which also occurred on June 12
and 13). For reference, it does NOT appear (at this time) that we
will break any record high temps today at these sites which are
listed as follows:
TLH: 100 set in 2011
ABY: 100 set in 1957
VLD: 101 set in 2011
Despite the very hot temps, we do expect dewpoints to mix out into
the upper 60s to lower 70s, which should keep Heat Indices just
below Heat Advisory Levels (108-113). The lone exception could be
around VLD and the Suwannee River Valley where a VERY few 108s and
109s could be possible. However, this area appears too small to
warrant an Advisory at this time, so will leave it out for now, and
let the day shift make any adjustments if needed. PoPs should be
quite low, generally in the 15-20% range, with only a few 30s
possible across parts of SE AL. This will also set the stage for a
very warm and humid night across the CWA tonight, with lows
generally in the mid to upper 70s from the interior to near the
coast.
&&
.SHORT TERM [Tuesday through Wednesday]...
GOES Blended TPW product and objective precipitable water analysis
from the RAP model shows a plume of above normal PWATs (2.1-2.2")
situated just to the west of our area over the Lower Mississippi
River Valley. This deeper moisture is expected to advect into our
area in the next 24 hours as the upper level ridge centered over
north Florida weakens. At the same time, we will see a weak front
approach from the north, and a weakness (or low-amplitude trough)
develop in the upper level ridge just west of our forecast area.
These ingredients suggest that rain will be on the increase
Tuesday and Wednesday - probably focused in the northwest half of
our area on Tuesday, and then spreading further into our area on
Wednesday. The high PWATs will be accompanied by very weak flow,
with projected storm motions at or below 5 knots (per NAM/GFS).
At least localized heavy rainfall is likely when you juxtapose
deep moisture and very slow storm motions. Therefore, we added
heavy rainfall wording to the forecast on Tuesday and Wednesday in
areas that have "likely" PoPs (>55%). For high temperatures we
kept a NW-SE gradient with the warmest conditions in the SE part
of our area. Low temperatures were kept fairly warm as there
should be an increase in cloud cover.
&&
.LONG TERM [Wednesday Night through Sunday]...
Not much change with the forecast pattern for later this week into
next weekend, as broad low amplitude trough becomes established
over the central Gulf Coast/southeast states. An attendant surface
front will likewise slide swd into the region. Combination of
these features suggests return to wetter than normal pattern,
which will also likely cap high temperatures a bit below normal
each day. We could see some heavy rainfall at times, with WPC
painting 3-3.5" totals on average over the tri-state region.
&&
.AVIATION [through 12 UTC Tuesday]...
Expect VFR conditions to prevail through the period with just few
to sct CU and CI the rest of the overnight hours and during the
day today. Although an isolated TSTM cannot be ruled out, the
minimal PoPs and coverage should preclude any mention of
convection at this time.
&&
.MARINE...
A relatively weak pressure pattern should persist despite the
approach of a weak front from the north. This should keep winds
around 10 knots or less, with seas 2 feet or less. Thunderstorm
activity over the waters should increase by Wednesday.
&&
.FIRE WEATHER...
Red flag conditions are not expected over the next several days,
although today will feature some of the lower RHs in many days.
&&
.HYDROLOGY...
Area river levels continue to slowly decrease or remain steady and
this should be the story of the next couple days. As a rainy
pattern re-emerges by mid-week, we should start to see flows on at
least a few of the rivers begin to increase again by late week or
into the weekend. It is too early to say which rivers may be
affected, as heavy rainfall could be somewhat localized.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 99 74 95 74 91 / 20 10 40 20 60
Panama City 93 79 90 78 88 / 20 20 40 20 50
Dothan 97 75 91 73 88 / 20 20 70 30 70
Albany 99 75 93 74 90 / 20 20 60 30 70
Valdosta 101 72 96 73 93 / 20 10 30 20 60
Cross City 97 72 94 74 93 / 10 10 20 10 30
Apalachicola 91 78 90 78 88 / 10 10 20 20 50
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...Barry
NEAR TERM...Gould
SHORT TERM...Lamers
LONG TERM...Evans
AVIATION...Gould
MARINE...Lamers
FIRE WEATHER...Gould
HYDROLOGY...Lamers
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1254 PM CDT MON AUG 12 2013
.DISCUSSION...
1135 AM CDT
FOR LATE MORNING UPDATE...
LITTLE/NO CHANGE TO GOING FORECAST...EXCEPT TO TWEAK CHANCE POP
COVERAGE AT MIDDAY BASED ON CURRENT RADAR/SATELLITE TRENDS AND COLD
FRONT POSITION. SPEAKING OF THE COLD FRONT...16Z SFC ANALYSIS
INDICATED IT WAS ROUGHLY FROM A WEAK LOW PRESSURE WAVE NEAR
MILWAUKEE...WEST TO NEAR JANESVILLE WI...THEN SOUTHWEST TO NEAR
SAVANNA AND MOLINE IL.
REGIONAL RADAR MOSAIC DEPICTS SCATTERED SHRA/TSRA OVER SOUTHERN LAKE
MICHIGAN AND SOUTHWEST LOWER MICHIGAN...ASSOCIATED WITH MOISTURE
TRANSPORT AND CONVERGENCE ON THE NOSE OF WEAKENING WESTERLY LOW
LEVEL JET AND WEAK SHORT WAVE NOTED IN VAPOR IMAGERY CURRENTLY
CROSSING THE LAKE EASTBOUND. OTHERWISE ONLY A FEW SHORT-LIVED
ISOLATED SHRA HAVE BEEN NOTED DURING THE MORNING HOURS MAINLY NEAR
THE SURFACE FRONT ACROSS FAR EAST/SOUTHEAST IOWA. EXPECTATION IS
THAT THIS WILL CHANGE OVER THE NEXT FEW HOURS HOWEVER...AS WEAK COLD
FRONT SLOWLY PUSHES SOUTHEAST ACROSS NORTHERN IL AND SOUTHERN LAKE
MICHIGAN DURING INCREASINGLY FAVORABLE TIMING OF DIURNAL
INSTABILITY. LOW LEVEL WARM SECTOR SOUTH OF THE COLD FRONTAL
BOUNDARY CHARACTERIZED BY LOW 80S TEMP/MID 60S DEW POINT CONDITIONS
WITH SOME WARMING STILL TO OCCUR ESPECIALLY ACROSS THE SOUTHEASTERN
PARTS OF THE CWA WHERE MORE SUNSHINE IS OCCURRING. CURRENT SPC/RAP
MESOANALYSIS INDICATES 500-1000 J/KG MLCAPE DEVELOPING IN THOSE
AREAS...AND EXTRAPOLATION FROM 12Z DVN RAOB AND FORECAST SOUNDINGS
FROM BOTH THE 12Z WRF-NAM/MOST RECENT 15Z RAP INDICATE 1000-1500
J/KG AVAILABLE DURING THE AFTERNOON HOURS...THOUGH THIN CIRRUS COVER
MAY NEGATIVELY AFFECT THIS A BIT. AIDING THE DESTABILIZATION OF THE
LOWER LEVELS WILL BE LARGER SCALE HEIGHT FALLS ACROSS THE UPPER
MIDWEST OCCURRING IN ASSOCIATION WITH A COUPLE OF SHORT WAVES
PIVOTING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND ANOTHER
DIGGING INTO THE UPPER MIDWEST FROM SOUTHERN MANITOBA. HOWEVER...THE
STRONGEST LARGE SCALE ASCENT AS WELL AS STRONGER MID/UPPER LEVEL
WINDS AND DEEP LAYER BULK SHEAR WILL GENERALLY REMAIN OFF TO THE
NORTH/NORTHEAST OF THE CWA THROUGH THE AFTERNOON.
THUS IT APPEARS THAT SHRA/TSRA WILL GRADUALLY DEVELOP AND INCREASE
IN COVERAGE ALONG/AHEAD OF THE WEAK COLD FRONT IS IT MOVES SOUTHEAST
ACROSS THE AREA THIS AFTERNOON (AND EARLY THIS EVENING). A FEW
STORMS MAY BECOME STRONG ACROSS THE SOUTHEAST CWA LATER THIS
AFTERNOON...PRESENTING PRIMARILY A 50-60 MPH WIND GUST THREAT. WHILE
NOT OUTLOOKED FOR SEVERE...SPC DOES HAVE OUR EAST/SOUTHEAST CWA
INCLUDED IN THE 5 PERCENT DAY 1 WIND RISK.
RATZER
//PREV DISCUSSION...
316 AM CDT
THE FORECAST FOCUSES ON SHRA/TSRA TRENDS TODAY FOLLOWED BY BELOW
NORMAL TEMPS AS A STRONG HIGH PRESSURE AREA BUILDS IN BEHIND AN
APPROACHING COLD FRONT. EARLY MORNING WATER VAPOR IMAGERY SHOWS A
BROAD UPPER TROUGH OVER EASTERN CANADA...THE UPPER MIDWEST...THE
GREAT LAKES...AND NORTHERN NEW ENGLAND WITH ITS CLOSED CENTER OVER
JAMES BAY. A CORRIDOR OF RIDGING EXTENDS FROM NEW MEXICO INTO
SOUTHERN ALBERTA WITH A MUCH SMALLER CLOSED UPPER LOW OVER NORTHERN
ALBERTA. ANOTHER CLOSED UPPER LOW IS SPINNING NORTHWARD UP THE
WESTERN FLANK OF THE RIDGE FROM THE WASHING TO TO BRITISH COLUMBIA
COAST. THE LOCAL AREA IS ON THE SOUTHERN PERIPHERY OF THE BROAD
EASTERN TROUGH AND AT THE JUNCTION OF A FEED OF MOISTURE FROM THE
WEST-SOUTHWEST AND SHORTWAVE ENERGY FROM THE WEST-NORTHWEST. AT THE
SURFACE...HIGH PRESSURE STRETCHES ALONG THE OHIO VALLEY WHILE
TROUGHING STRETCHES FROM SOUTHERN QUEBEC ACROSS LAKE SUPERIOR AND
INTO CENTRAL WISCONSIN AND IOWA. SURFACE OBS SUGGEST A CLOSED LOW
OVER FAR NORTHERN WISCONSIN OR LAKE SUPERIOR WITH A COOL FRONTAL
BOUNDARY STRETCHING FROM THIS LOW SOUTHWEST TO JUST NORTH OF THE
TWIN CITIES TO EXTREME SW MINNESOTA AT 08Z.
TODAY AND TONIGHT...SHRA/TSRA POTENTIAL WILL BE A CHALLENGE TODAY.
CLUSTERS OF SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE EASTWARD
ACROSS FAR SOUTHERN WISCONSIN COINCIDENT WITH A SHARP LOW/MID LEVEL
THERMAL GRADIENT WITH ASCENT BEING AIDED BY MODEST BUT STILL FOCUSED
LOW LEVEL JET. VAD WIND PROFILES DO SHOW THE BEST CONVERGENCE
ASSOCIATED WITH THIS PRECIP WITH LESSER CONVERGENCE TO THE
SOUTHWEST ACROSS CENTRAL AND NORTHEAST IOWA WHERE CONVECTION HAS
STRUGGLED TO CONTINUE. THE BAROCLINIC ZONE IS EXPECTED TO START TO
SAG SOUTHWARD INTO FAR NORTHERN ILLINOIS OVER THE NEXT FEW HOURS
SUGGESTING THAT THERE MAY BE AT LEAST SOME SMALL INCREASE IN
SHRA/TSRA COVERAGE ACROSS THE NORTHERN CWA BUT THE LOW LEVEL JET
WILL START TO WANE SO ANY NEW ACTIVITY MAY BE SHORT LIVED. THE
AFOREMENTIONED COLD FRONT WILL BE WORKING SOUTHEASTWARD THROUGH
THE MORNING AND SHOULD REACH THE FAR NORTHWEST CWA BY LATE
MORNING. WITH THE LOW LEVEL JET WEAKENING DURING THE MORNING
PRECIP ACTIVITY LOOKS TO WANE WITH THE FRONT ITSELF NEEDING TO
TAKE OVER AS THE MAIN FORCING MECHANISM FOR NEW DEVELOPMENT.
ABUNDANT MID AND HIGH CLOUD COVER CONTINUES TO STREAM OVER THE
REGION WITH THICKER CLOUDS APPROACHING FROM THE PRECIP ACTIVITY
OVER IOWA. THIS WILL BE KEY IN DETERMINING HOW MUCH INSTABILITY
DEVELOPS AND WHERE IT DOES SO. TIMING OF THE FRONT WILL ALSO
DETERMINE HOW MUCH OF THE AREA WILL SEE A SHRA/TSRA THREAT THROUGH
THE DAY. NEAR TERM GUIDANCE SHOWS SOME DISCREPANCIES WITH THE
SPEED OF THE FRONT BUT OVERALL PREFER A SLOWER APPROACH GIVEN THE
FAIRLY UNIDIRECTIONAL STEERING FLOW AND THE PRESENCE OF THE
CURRENT CONVECTION. THIS THINKING WOULD BRING THE FRONT THROUGH
THE CHICAGO AREA AND POINTS WEST DURING MIDDAY OR EARLY AFTERNOON.
THIS LINE OF THINKING ALSO SUPPORTS THAT THE BEST THUNDER THREAT
WILL BE ACROSS THE SOUTHERN HALF OR SO OF THE AREA AS HEATING
INCREASES AND DESTABILIZATION COMMENCES. IT ALSO APPEARS THAT
THERE WILL BE SOME LARGER SCALE ASCENT PROVIDED BY A WEAK COUPLING
OF BRANCHES OF THE UPPER JET THIS AFTERNOON. WITH THIS IN MIND
WILL CONTINUE TO FOCUS THE GREATEST AFTERNOON POPS FROM NEAR GARY
SOUTHWEST TO PONTIAC AND POINTS SOUTH BUT NEW DEVELOPMENT MAY
INITIATE JUST TO THE NORTH OF THIS LINE ACROSS THE CHICAGO METRO
AND POINTS WEST ALONG INTERSTATE 80...ESPECIALLY IF THE FRONT IS A
BIT SLOWER. IN ADDITION...THERE DOES LOOK TO BE SOME INSTABILITY
BEHIND THE FRONT AND SOME SIGNS OF POSSIBLE ENHANCED CONVERGENCE
ALONG THE LAKESHORE AS WINDS TURN NORTHERLY WHICH COULD PROVIDE
SOME FOCUS FOR CONVECTION AS WELL. PROVIDED THAT THE EXPECTED
HEATING OCCURS THEN AREAS AHEAD OF THE FRONT WILL LIKELY SEE
1500-2000 J/KG OF CAPE THIS AFTERNOON. DEEP LAYER SHEAR WILL BE ON
THE ORDER OF ABOUT 30 KT. THIS WILL SUPPORT A SEVERE HAIL AND WIND
THREAT FROM THE BEST ORGANIZED STORMS ACROSS THE SOUTHERN HALF OF
THE AREA. OVERALL COVERAGE OF STORMS MAY ONLY BE SCATTERED WITH
CLOUD COVER BEING A LIMITATION SO WILL TOP POPS OUT IN THE HIGH
CHANCE CATEGORY. THE FRONT WILL BE SLOW TO EXIT TO THE SOUTH SO
SOUTHERN AREAS WILL SEE A CONTINUED SHRA/TSRA CHANCE ACROSS THE
FAR SOUTH THIS EVENING. HIGHS TODAY SHOULD RANGE FROM AROUND 80
NORTH TO THE MID 80S SOUTH.
TUESDAY THROUGH SUNDAY...STRONG HIGH PRESSURE WILL BE SPREADING
SOUTHWARD INTO THE MID AND UPPER MISSISSIPPI RIVER VALLEY TUESDAY
RESULTING IN NORTHERLY LOW LEVEL WINDS ACROSS THE CWA. THE BROAD
UPPER LEVEL TROUGH WILL HAVE SHARPENED UP WITH A TROUGH AXIS
DROPPING SOUTHEAST ACROSS THE AREA LATER IN THE DAY.
ACCORDINGLY...MUCH COOLER AIR WILL BE SPILLING INTO THE
AREA...ESPECIALLY FOLLOWING THE PASSAGE OF THE EMBEDDED TROUGH AXIS.
EXPECT H85 TEMPS TO TUMBLE FROM A PEAK OF AROUND +16C THIS AFTERNOON
TO AROUND +8C BY TUESDAY EVENING. EXPECT TUESDAY TO BE DRY DESPITE
THE PASSAGE OF THE TROUGH...GIVEN THAT THE ATMOSPHERE WILL BE
NOTICEABLY DRIER...THOUGH LOW LEVEL LAPSE RATES DO LOOK TO BE QUITE
SHARP...BUT THEY ARE SOMEWHAT SHALLOW. HIGHS WILL RANGE FROM THE
LOWER 70S WITHIN SEVERAL MILES OF LAKE MICHIGAN TO THE MID 70S
FURTHER INLAND. THE HIGH WILL CONTINUE TO PUSH SOUTH AND PARK ITSELF
OVER THE LOCAL AREA BY LATE WEDNESDAY. AN UPPER TROUGH WILL
GRADUALLY AMPLIFY AS RIDGING SHARPENS OVER THE WESTERN U.S. THROUGH
THE END OF THE WEEK. THE HIGH WILL SLOWLY WEAKEN AND THE AIRMASS
WILL SLOWLY MODIFY THROUGH THE END OF THE WEEK BUT MOST AREAS WILL
REMAIN IN THE 70S FOR HIGHS THROUGH FRIDAY...WITH MOST AREAS BEING
AROUND 80 FOR THE WEEKEND. AT THIS POINT THE REMAINDER OF THE WEEK
AND NEXT WEEKEND LOOK DRY BUT SOME MOISTURE MAY WORK ITS WAY INTO
THE EASTERN CWA TOWARD SUNDAY AS AN UPPER CIRCULATION EJECTS
NORTHWARD OVER THE MIDDLE OHIO VALLEY.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* CHANCE OF SHRA/TSRA THROUGH MID/LATE AFTERNOON.
* WIND SHIFT TO NORTHEAST MID/LATE AFTERNOON.
* CHANCE OF MVFR CIGS OVERNIGHT/EARLY TUESDAY MORNING. CMS
//DISCUSSION...UPDATED 18Z...
SEVERAL FORECAST CONCERNS THIS PERIOD WITH THE TWO PRIMARY
CONCERNS TSRA POTENTIAL AND WIND SHIFT...BOTH THIS AFTERNOON.
A COLD FRONT EXTENDING FROM SOUTHEAST WI THROUGH NORTHWEST IL WILL
CONTINUE TO MOVE ACROSS THE TERMINALS THROUGH MID AFTERNOON. WINDS
HAVE SHIFTED LIGHT NORTHEASTERLY ACROSS SOUTHEAST WI AND WITH
PRECIP NOW DEVELOPING ALONG THE FRONT ACROSS FAR SOUTHEAST WI...
EXPECT THIS TO AID THE COLD FRONT/LAKE BREEZE TO ACCELERATE TO THE
SOUTHWEST THROUGH THE AFTERNOON. SO WHILE WINDS PROBABLY WILL TURN
NORTHWEST AT ORD/MDW...NOT SURE THE DURATION WILL BE TOO LONG AS
WINDS WILL LIKELY SHIFT NORTHEAST SOONER RATHER THAN LATER BUT
WILL NEED TO MONITOR TRENDS INTO THE AFTERNOON.
SHORT TERM/HI RES GUIDANCE HAS BEEN IN FAIR AGREEMENT WITH SHRA/
TSRA DEVELOPMENT EARLY THIS AFTERNOON ACROSS NORTHERN IL AND THEN
SHIFTING IT SLOWLY SOUTHEAST ACROSS THE TERMINALS THROUGH MID/LATE
AFTERNOON BUT CURRENT ACTIVITY HAS DEVELOPED A LITTLE FURTHER
NORTH AND SO FAR HAS REMAINED ISOLATED. MAINTAINED PREVIOUS VCTS
TIMING BUT EXPECT THIS WILL NEED TO BE TWEAKED...IN PARTICULAR...
PRECIP MAY LINGER A BIT LONGER THEN CURRENTLY ADVERTISED.
MVFR CLOUDS ACROSS SOUTHERN WI ESPECIALLY OVER SOUTHEAST WI COULD
DRIFT SOUTH BEHIND THE COLD FRONT/LAKE BREEZE BUT CONFIDENCE
REGARDING ANY POTENTIAL MVFR CIGS LATER THIS AFTERNOON...AND
THEIR DURATION IS LOW. A SECONDARY SURGE OF COLDER AIR ARRIVES
LATE TONIGHT AND AS THIS SPREADS ACROSS THE AREA...EXPECT SOME
LOWER CLOUD POTENTIAL...IN THE 1-2KFT RANGE BUT CIGS MAY BE
CONFINED CLOSER TO THE LAKE.
NORTH/NORTHEAST WINDS WILL DIMINISH THIS EVENING...POSSIBLY
TURNING BACK NORTHWESTERLY UNTIL THAT SURGE OF COLDER AIR ARRIVES
AND TURNS WINDS BACK NORTH/NORTHEAST WITH SPEEDS 10-12KTS. AFTER
SUNRISE...LOW LEVELS BEGIN TO MIX WITH GUSTS 18-20KTS POSSIBLE
THROUGH EARLY AFTERNOON. CMS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM FOR SHRA/TSRA THROUGH MID/LATE AFTERNOON...LOW FOR DIRECT
IMPACTS AT ORD/MDW.
* HIGH FOR A WIND SHIFT TO THE NORTH/NORTHEAST MID/LATE
AFTERNOON...MEDIUM FOR TIMING.
* LOW FOR POTENTIAL MVFR CIGS OVERNIGHT/EARLY TUESDAY MORNING.
* HIGH FOR WIND SPEEDS/GUSTS OVERNIGHT/TUESDAY. CMS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...VFR. DAILY LAKE BREEZE WIND SHIFTS
EXPECTED.
RC
&&
.MARINE...
304 AM CDT
A COLD FRONT WILL PUSH DOWN THE LAKE TODAY...WITH WINDS VEERING
FROM SOUTHWEST TO NORTH BEHIND THE FRONT. AS LARGE HIGH PRESSURE
BUILDS IN FROM THE NORTHWEST AND A COOL AIR MASS FILTERS INTO THE
REGION...WINDS WILL INCREASE TONIGHT...STRONGEST ON THE NORTH DUE
TO A SECONDARY EVEN STRONGER PUSH OF COLD AIR. SUSTAINED WINDS TO
20 KT WITH FREQUENT GUSTS INTO THE MID 20S KT RANGE ARE
EXPECTED...WITH EVEN A FEW 30 KT GUSTS POSSIBLE BEFORE WINDS BEGIN
TO EASE TOWARD DAYBREAK TUESDAY. THE SECONDARY PUSH OF COOL AIR
WILL ARRIVE ON THE SOUTH HALF OF THE LAKE DURING THE DAY ON
TUESDAY...RESULTING IN A SIMILAR INCREASE IN NORTHERLY WINDS TO 20
TO 25 KT WITH A FEW 30 KT GUSTS. WILL LIKELY NEED A SMALL CRAFT
ADVISORY FOR THE NEARSHORE WATERS STARTING SOME TIME TUESDAY
AFTERNOON AS WAVES BUILD UNTIL THEY SUBSIDE WEDNESDAY MORNING.
HIGH PRESSURE WILL ESTABLISH ITSELF OVER THE GREAT LAKES REGION
TUESDAY NIGHT...CAUSING WINDS TO DIMINISH FOR THE ENTIRE LAKE.
THIS HIGH WILL MORE OR LESS REMAIN IN PLACE THROUGH THE END OF THE
WEEK...RESULTING IN AN EXTENDED PERIOD OF LIGHT WINDS. THERE WILL
BE DAILY LAKE INFLUENCE FOR THE NEARSHORE WATERS AND LIKELY
VARIABILITY IN WIND DIRECTION OVER THE OPEN WATERS DUE TO THE WEAK
PRESSURE GRADIENT.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1136 AM CDT MON AUG 12 2013
.DISCUSSION...
1135 AM CDT
FOR LATE MORNING UPDATE...
LITTLE/NO CHANGE TO GOING FORECAST...EXCEPT TO TWEAK CHANCE POP
COVERAGE AT MIDDAY BASED ON CURRENT RADAR/SATELLITE TRENDS AND COLD
FRONT POSITION. SPEAKING OF THE COLD FRONT...16Z SFC ANALYSIS
INDICATED IT WAS ROUGHLY FROM A WEAK LOW PRESSURE WAVE NEAR
MILWAUKEE...WEST TO NEAR JANESVILLE WI...THEN SOUTHWEST TO NEAR
SAVANNA AND MOLINE IL.
REGIONAL RADAR MOSAIC DEPICTS SCATTERED SHRA/TSRA OVER SOUTHERN LAKE
MICHIGAN AND SOUTHWEST LOWER MICHIGAN...ASSOCIATED WITH MOISTURE
TRANSPORT AND CONVERGENCE ON THE NOSE OF WEAKENING WESTERLY LOW
LEVEL JET AND WEAK SHORT WAVE NOTED IN VAPOR IMAGERY CURRENTLY
CROSSING THE LAKE EASTBOUND. OTHERWISE ONLY A FEW SHORT-LIVED
ISOLATED SHRA HAVE BEEN NOTED DURING THE MORNING HOURS MAINLY NEAR
THE SURFACE FRONT ACROSS FAR EAST/SOUTHEAST IOWA. EXPECTATION IS
THAT THIS WILL CHANGE OVER THE NEXT FEW HOURS HOWEVER...AS WEAK COLD
FRONT SLOWLY PUSHES SOUTHEAST ACROSS NORTHERN IL AND SOUTHERN LAKE
MICHIGAN DURING INCREASINGLY FAVORABLE TIMING OF DIURNAL
INSTABILITY. LOW LEVEL WARM SECTOR SOUTH OF THE COLD FRONTAL
BOUNDARY CHARACTERIZED BY LOW 80S TEMP/MID 60S DEW POINT CONDITIONS
WITH SOME WARMING STILL TO OCCUR ESPECIALLY ACROSS THE SOUTHEASTERN
PARTS OF THE CWA WHERE MORE SUNSHINE IS OCCURRING. CURRENT SPC/RAP
MESOANALYSIS INDICATES 500-1000 J/KG MLCAPE DEVELOPING IN THOSE
AREAS...AND EXTRAPOLATION FROM 12Z DVN RAOB AND FORECAST SOUNDINGS
FROM BOTH THE 12Z WRF-NAM/MOST RECENT 15Z RAP INDICATE 1000-1500
J/KG AVAILABLE DURING THE AFTERNOON HOURS...THOUGH THIN CIRRUS COVER
MAY NEGATIVELY AFFECT THIS A BIT. AIDING THE DESTABILIZATION OF THE
LOWER LEVELS WILL BE LARGER SCALE HEIGHT FALLS ACROSS THE UPPER
MIDWEST OCCURRING IN ASSOCIATION WITH A COUPLE OF SHORT WAVES
PIVOTING SOUTHEAST ACROSS THE UPPER MISSISSIPPI VALLEY AND ANOTHER
DIGGING INTO THE UPPER MIDWEST FROM SOUTHERN MANITOBA. HOWEVER...THE
STRONGEST LARGE SCALE ASCENT AS WELL AS STRONGER MID/UPPER LEVEL
WINDS AND DEEP LAYER BULK SHEAR WILL GENERALLY REMAIN OFF TO THE
NORTH/NORTHEAST OF THE CWA THROUGH THE AFTERNOON.
THUS IT APPEARS THAT SHRA/TSRA WILL GRADUALLY DEVELOP AND INCREASE
IN COVERAGE ALONG/AHEAD OF THE WEAK COLD FRONT IS IT MOVES SOUTHEAST
ACROSS THE AREA THIS AFTERNOON (AND EARLY THIS EVENING). A FEW
STORMS MAY BECOME STRONG ACROSS THE SOUTHEAST CWA LATER THIS
AFTERNOON...PRESENTING PRIMARILY A 50-60 MPH WIND GUST THREAT. WHILE
NOT OUTLOOKED FOR SEVERE...SPC DOES HAVE OUR EAST/SOUTHEAST CWA
INCLUDED IN THE 5 PERCENT DAY 1 WIND RISK.
RATZER
&&
.PREV DISCUSSION...
316 AM CDT
THE FORECAST FOCUSES ON SHRA/TSRA TRENDS TODAY FOLLOWED BY BELOW
NORMAL TEMPS AS A STRONG HIGH PRESSURE AREA BUILDS IN BEHIND AN
APPROACHING COLD FRONT. EARLY MORNING WATER VAPOR IMAGERY SHOWS A
BROAD UPPER TROUGH OVER EASTERN CANADA...THE UPPER MIDWEST...THE
GREAT LAKES...AND NORTHERN NEW ENGLAND WITH ITS CLOSED CENTER OVER
JAMES BAY. A CORRIDOR OF RIDGING EXTENDS FROM NEW MEXICO INTO
SOUTHERN ALBERTA WITH A MUCH SMALLER CLOSED UPPER LOW OVER NORTHERN
ALBERTA. ANOTHER CLOSED UPPER LOW IS SPINNING NORTHWARD UP THE
WESTERN FLANK OF THE RIDGE FROM THE WASHING TO TO BRITISH COLUMBIA
COAST. THE LOCAL AREA IS ON THE SOUTHERN PERIPHERY OF THE BROAD
EASTERN TROUGH AND AT THE JUNCTION OF A FEED OF MOISTURE FROM THE
WEST-SOUTHWEST AND SHORTWAVE ENERGY FROM THE WEST-NORTHWEST. AT THE
SURFACE...HIGH PRESSURE STRETCHES ALONG THE OHIO VALLEY WHILE
TROUGHING STRETCHES FROM SOUTHERN QUEBEC ACROSS LAKE SUPERIOR AND
INTO CENTRAL WISCONSIN AND IOWA. SURFACE OBS SUGGEST A CLOSED LOW
OVER FAR NORTHERN WISCONSIN OR LAKE SUPERIOR WITH A COOL FRONTAL
BOUNDARY STRETCHING FROM THIS LOW SOUTHWEST TO JUST NORTH OF THE
TWIN CITIES TO EXTREME SW MINNESOTA AT 08Z.
TODAY AND TONIGHT...SHRA/TSRA POTENTIAL WILL BE A CHALLENGE TODAY.
CLUSTERS OF SHOWERS AND THUNDERSTORMS CONTINUE TO MOVE EASTWARD
ACROSS FAR SOUTHERN WISCONSIN COINCIDENT WITH A SHARP LOW/MID LEVEL
THERMAL GRADIENT WITH ASCENT BEING AIDED BY MODEST BUT STILL FOCUSED
LOW LEVEL JET. VAD WIND PROFILES DO SHOW THE BEST CONVERGENCE
ASSOCIATED WITH THIS PRECIP WITH LESSER CONVERGENCE TO THE
SOUTHWEST ACROSS CENTRAL AND NORTHEAST IOWA WHERE CONVECTION HAS
STRUGGLED TO CONTINUE. THE BAROCLINIC ZONE IS EXPECTED TO START TO
SAG SOUTHWARD INTO FAR NORTHERN ILLINOIS OVER THE NEXT FEW HOURS
SUGGESTING THAT THERE MAY BE AT LEAST SOME SMALL INCREASE IN
SHRA/TSRA COVERAGE ACROSS THE NORTHERN CWA BUT THE LOW LEVEL JET
WILL START TO WANE SO ANY NEW ACTIVITY MAY BE SHORT LIVED. THE
AFOREMENTIONED COLD FRONT WILL BE WORKING SOUTHEASTWARD THROUGH
THE MORNING AND SHOULD REACH THE FAR NORTHWEST CWA BY LATE
MORNING. WITH THE LOW LEVEL JET WEAKENING DURING THE MORNING
PRECIP ACTIVITY LOOKS TO WANE WITH THE FRONT ITSELF NEEDING TO
TAKE OVER AS THE MAIN FORCING MECHANISM FOR NEW DEVELOPMENT.
ABUNDANT MID AND HIGH CLOUD COVER CONTINUES TO STREAM OVER THE
REGION WITH THICKER CLOUDS APPROACHING FROM THE PRECIP ACTIVITY
OVER IOWA. THIS WILL BE KEY IN DETERMINING HOW MUCH INSTABILITY
DEVELOPS AND WHERE IT DOES SO. TIMING OF THE FRONT WILL ALSO
DETERMINE HOW MUCH OF THE AREA WILL SEE A SHRA/TSRA THREAT THROUGH
THE DAY. NEAR TERM GUIDANCE SHOWS SOME DISCREPANCIES WITH THE
SPEED OF THE FRONT BUT OVERALL PREFER A SLOWER APPROACH GIVEN THE
FAIRLY UNIDIRECTIONAL STEERING FLOW AND THE PRESENCE OF THE
CURRENT CONVECTION. THIS THINKING WOULD BRING THE FRONT THROUGH
THE CHICAGO AREA AND POINTS WEST DURING MIDDAY OR EARLY AFTERNOON.
THIS LINE OF THINKING ALSO SUPPORTS THAT THE BEST THUNDER THREAT
WILL BE ACROSS THE SOUTHERN HALF OR SO OF THE AREA AS HEATING
INCREASES AND DESTABILIZATION COMMENCES. IT ALSO APPEARS THAT
THERE WILL BE SOME LARGER SCALE ASCENT PROVIDED BY A WEAK COUPLING
OF BRANCHES OF THE UPPER JET THIS AFTERNOON. WITH THIS IN MIND
WILL CONTINUE TO FOCUS THE GREATEST AFTERNOON POPS FROM NEAR GARY
SOUTHWEST TO PONTIAC AND POINTS SOUTH BUT NEW DEVELOPMENT MAY
INITIATE JUST TO THE NORTH OF THIS LINE ACROSS THE CHICAGO METRO
AND POINTS WEST ALONG INTERSTATE 80...ESPECIALLY IF THE FRONT IS A
BIT SLOWER. IN ADDITION...THERE DOES LOOK TO BE SOME INSTABILITY
BEHIND THE FRONT AND SOME SIGNS OF POSSIBLE ENHANCED CONVERGENCE
ALONG THE LAKESHORE AS WINDS TURN NORTHERLY WHICH COULD PROVIDE
SOME FOCUS FOR CONVECTION AS WELL. PROVIDED THAT THE EXPECTED
HEATING OCCURS THEN AREAS AHEAD OF THE FRONT WILL LIKELY SEE
1500-2000 J/KG OF CAPE THIS AFTERNOON. DEEP LAYER SHEAR WILL BE ON
THE ORDER OF ABOUT 30 KT. THIS WILL SUPPORT A SEVERE HAIL AND WIND
THREAT FROM THE BEST ORGANIZED STORMS ACROSS THE SOUTHERN HALF OF
THE AREA. OVERALL COVERAGE OF STORMS MAY ONLY BE SCATTERED WITH
CLOUD COVER BEING A LIMITATION SO WILL TOP POPS OUT IN THE HIGH
CHANCE CATEGORY. THE FRONT WILL BE SLOW TO EXIT TO THE SOUTH SO
SOUTHERN AREAS WILL SEE A CONTINUED SHRA/TSRA CHANCE ACROSS THE
FAR SOUTH THIS EVENING. HIGHS TODAY SHOULD RANGE FROM AROUND 80
NORTH TO THE MID 80S SOUTH.
TUESDAY THROUGH SUNDAY...STRONG HIGH PRESSURE WILL BE SPREADING
SOUTHWARD INTO THE MID AND UPPER MISSISSIPPI RIVER VALLEY TUESDAY
RESULTING IN NORTHERLY LOW LEVEL WINDS ACROSS THE CWA. THE BROAD
UPPER LEVEL TROUGH WILL HAVE SHARPENED UP WITH A TROUGH AXIS
DROPPING SOUTHEAST ACROSS THE AREA LATER IN THE DAY.
ACCORDINGLY...MUCH COOLER AIR WILL BE SPILLING INTO THE
AREA...ESPECIALLY FOLLOWING THE PASSAGE OF THE EMBEDDED TROUGH AXIS.
EXPECT H85 TEMPS TO TUMBLE FROM A PEAK OF AROUND +16C THIS AFTERNOON
TO AROUND +8C BY TUESDAY EVENING. EXPECT TUESDAY TO BE DRY DESPITE
THE PASSAGE OF THE TROUGH...GIVEN THAT THE ATMOSPHERE WILL BE
NOTICEABLY DRIER...THOUGH LOW LEVEL LAPSE RATES DO LOOK TO BE QUITE
SHARP...BUT THEY ARE SOMEWHAT SHALLOW. HIGHS WILL RANGE FROM THE
LOWER 70S WITHIN SEVERAL MILES OF LAKE MICHIGAN TO THE MID 70S
FURTHER INLAND. THE HIGH WILL CONTINUE TO PUSH SOUTH AND PARK ITSELF
OVER THE LOCAL AREA BY LATE WEDNESDAY. AN UPPER TROUGH WILL
GRADUALLY AMPLIFY AS RIDGING SHARPENS OVER THE WESTERN U.S. THROUGH
THE END OF THE WEEK. THE HIGH WILL SLOWLY WEAKEN AND THE AIRMASS
WILL SLOWLY MODIFY THROUGH THE END OF THE WEEK BUT MOST AREAS WILL
REMAIN IN THE 70S FOR HIGHS THROUGH FRIDAY...WITH MOST AREAS BEING
AROUND 80 FOR THE WEEKEND. AT THIS POINT THE REMAINDER OF THE WEEK
AND NEXT WEEKEND LOOK DRY BUT SOME MOISTURE MAY WORK ITS WAY INTO
THE EASTERN CWA TOWARD SUNDAY AS AN UPPER CIRCULATION EJECTS
NORTHWARD OVER THE MIDDLE OHIO VALLEY.
MDB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* CHANCE OF SHRA/TSRA EARLY/MID AFTERNOON.
* COLD FRONT/WIND SHIFT FROM WESTERLY...TO NORTHERLY THEN TO
NORTHEASTERLY MID/LATE AFTERNOON. CMS
//DISCUSSION...UPDATED 12Z...
PRIMARY AVIATION CONCERN IS ON AN UNCERTAIN CONVECTIVE FORECAST
FOR TODAY. A COLD FRONT WILL SAG SOUTH ACROSS THE TERMINALS TODAY
FROM THE EARLY THROUGH MID TO LATE AFTERNOON. WINDS WILL TURN FROM
SOUTHWEST TO MORE WESTERLY AS THE FRONT APPROACHES AND THEN NORTH-
NORTHWEST TO NORTH BEHIND THE FRONT. ENOUGH INSTABILITY IS
EXPECTED TO BUILD TO SUPPORT SCATTERED SHRA AND TSRA MOVING
SOUTHEAST...THOUGH HAVE THE MOST CONFIDENCE IN GYY AND POINTS
SOUTH. FOR ORD/MDW/DPA...HAVE REASONABLE CONFIDENCE IN TSRA IN THE
AREA...BUT LOW CONFIDENCE IN DIRECT TERMINAL IMPACTS SO FOR NOW
HAVE GONE WITH A -SHRA VCTS MENTION FROM EARLY TO MID
AFTERNOON...WHICH WILL ALLOW FOR ASSESSMENT OF CONVECTIVE
EVOLUTION TODAY AND UPDATES/REFINEMENT IF NEEDED. IF TSRA DIRECTLY
IMPACT THE TERMINALS...WOULD EXPECT MVFR OR POSSIBLY LOWER VSBY.
NEXT CONCERN IS AN EXPECTED WIND SHIFT TO NORTHEAST AT
ORD/MDW/GYY...WHICH SHOULD OCCUR FAIRLY QUICKLY AFTER THE SHIFT TO
NORTH-NORTHWEST...BUT REFINEMENT OF THE TIMING CURRENTLY
INDICATED COULD BE NEEDED. THERE MAY BE ENOUGH LINGERING
INSTABILITY FOR SHRA DEVELOPMENT WITH THE LAKE BREEZE. WINDS WILL
DIMINISH OVERNIGHT INTO EARLY TUESDAY WITH VFR CONDITIONS EXPECTED
BUT MAY NEED TO WATCH FOR LOWER CIGS DEVELOPING AS A COOL AIR MASS
PUSHES DOWN LAKE MICHIGAN. A SECONDARY PUSH OF COOLER AIR
OCCURRING AS STRONG HIGH PRESSURE BUILDS IN FROM THE NORTHWEST ON
TUESDAY WILL RESULT IN OCCASIONALLY GUSTY NORTHEAST WINDS WITH
SPEEDS LIKELY AT 10 KT OR HIGHER.
RC
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM FOR TSRA OCCURRING NEAR THE TERMINALS EARLY/MID
AFTERNOON...LOW FOR TSRA DIRECTLY IMPACTING THE TERMINALS.
* MEDIUM FOR TIMING OF FRONTAL PASSAGE/WIND SHIFT TO NORTH-
NORTHWEST AND THEN TO NORTHEAST. CMS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
TUESDAY NIGHT THROUGH SUNDAY...VFR. DAILY LAKE BREEZE WIND SHIFTS
EXPECTED.
RC
&&
.MARINE...
304 AM CDT
A COLD FRONT WILL PUSH DOWN THE LAKE TODAY...WITH WINDS VEERING
FROM SOUTHWEST TO NORTH BEHIND THE FRONT. AS LARGE HIGH PRESSURE
BUILDS IN FROM THE NORTHWEST AND A COOL AIR MASS FILTERS INTO THE
REGION...WINDS WILL INCREASE TONIGHT...STRONGEST ON THE NORTH DUE
TO A SECONDARY EVEN STRONGER PUSH OF COLD AIR. SUSTAINED WINDS TO
20 KT WITH FREQUENT GUSTS INTO THE MID 20S KT RANGE ARE
EXPECTED...WITH EVEN A FEW 30 KT GUSTS POSSIBLE BEFORE WINDS BEGIN
TO EASE TOWARD DAYBREAK TUESDAY. THE SECONDARY PUSH OF COOL AIR
WILL ARRIVE ON THE SOUTH HALF OF THE LAKE DURING THE DAY ON
TUESDAY...RESULTING IN A SIMILAR INCREASE IN NORTHERLY WINDS TO 20
TO 25 KT WITH A FEW 30 KT GUSTS. WILL LIKELY NEED A SMALL CRAFT
ADVISORY FOR THE NEARSHORE WATERS STARTING SOME TIME TUESDAY
AFTERNOON AS WAVES BUILD UNTIL THEY SUBSIDE WEDNESDAY MORNING.
HIGH PRESSURE WILL ESTABLISH ITSELF OVER THE GREAT LAKES REGION
TUESDAY NIGHT...CAUSING WINDS TO DIMINISH FOR THE ENTIRE LAKE.
THIS HIGH WILL MORE OR LESS REMAIN IN PLACE THROUGH THE END OF THE
WEEK...RESULTING IN AN EXTENDED PERIOD OF LIGHT WINDS. THERE WILL
BE DAILY LAKE INFLUENCE FOR THE NEARSHORE WATERS AND LIKELY
VARIABILITY IN WIND DIRECTION OVER THE OPEN WATERS DUE TO THE WEAK
PRESSURE GRADIENT.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1236 PM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 1235 PM CDT MON AUG 12 2013
THE COLD FRONT CONTINUES TO MAKE STEADY PROGRESS ACROSS THE CWA
AND WAS CURRENTLY LOCATED FROM ABOUT PRINCETON IL TO JUST NORTH OF
BURLINGTON IA AND THEN INTO NW MO. A FEW SHOWERS AND ISOLATED
THUNDERSTORMS WERE LOCATED IN EXTREME SOUTHEAST IA...WESTERN IL AND
EXTREME NORTHEAST MO ALONG AND AHEAD OF THE FRONT. THE RAPID
REFRESH MESO MODEL INDICATES THE BULK OF THE SHOWERS WILL END BY
LATE THIS AFTERNOON. UPDATED GRIDS LATE THIS MORNING TO INCREASE
POPS TO 50 PERCENT IN OUR FAR SOUTHERN COUNTIES AS THE FRONT
ENCOUNTERS HIGHER MOISTURE VALUES WITH PRECIPITABLE WATER OF 1.50
INCHES.
IN THE MEANTIME...CLEARING SKIES WAS PUSHING INTO OUR FAR NW
COUNTIES AS COOLER AND DRIER AIR BEGIN FILTERING IN FROM THE
NORTHWEST.
UPDATE ISSUED AT 1120 AM CDT MON AUG 12 2013
COLD FRONT EXTENDED FROM NEAR FREEPORT TO THE QUAD CITIES TO JUST
SOUTH OF OTTUMWA AND WAS MOVING SOUTHEAST. ONLY ISOLATED SHOWERS
HAVE OCCURRED ALONG THE FRONT SO FAR WITH THE MAIN AREA OF
THUNDERSTORMS IN MISSOURI. RAPID REFRESH MESO MODEL INDICATES A
FEW SHOWERS AND THUNDERSTORMS WILL GRAZE OUR FAR SOUTHERN COUNTIES
THROUGH THE MID AFTERNOON HOURS AHEAD OF THE FRONT.
HAVE LOWERED TEMPERATURES A FEW DEGREES DUE TO EXTENSIVE CLOUD
COVER. HOWEVER...SKIES WERE CLEARING ACROSS NORTHERN AND WESTERN
IA AND NORTH INTO MN AS COOLER AND DRIER AIR FEED INTO THOSE AREAS.
UPDATE ISSUED AT 702 AM CDT MON AUG 12 2013
THE NOCTURNAL CONVECTION HAS DISSIPATED ACROSS THE AREA. TRENDS
FROM THE RAP INDICATE DOWNWARD MOTION HAS DEVELOPED SINCE MIDNIGHT
BEHIND A WEAK VORT MAX AND THIS DOWNWARD MOTION WILL PERSIST
THROUGH LATE MORNING.
THE MCS AND LIFT TOOLS GIVE MIXED SIGNALS ON THE POTENTIAL FOR
DIURNAL CONVECTION THIS AFTERNOON. IF CONVECTION DOES OCCUR...IT
WILL BE MAINLY ISOLATED TO POSSIBLY SCATTERED AND GENERALLY OVER
THE SOUTHEAST THIRD TO 40 PERCENT OF THE CWFA. TRENDS WITH THE RAP
MODEL SUGGEST ANY CONVECTION WILL BE NEARLY GONE ACROSS THE CWFA
BY EARLY EVENING. ..08..
&&
.SYNOPSIS...
ISSUED AT 319 AM CDT MON AUG 12 2013
06Z SFC ANALYSIS HAS A WEAK LOW WEST OF KMIW WITH A WARM FRONT TO
NEAR KCID. A COLD FRONT RAN FROM THE LOW INTO SOUTHERN NEBRASKA.
ANOTHER WEAK LOW WAS AT KLSE WITH A TROF CONNECTING THAT LOW WITH
THE LOW NEAR KMIW. DEW POINTS WERE IN THE 50S AND 60S ACROSS THE
MIDWEST WITH 70S ACROSS THE DEEP SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 319 AM CDT MON AUG 12 2013
RADAR TRENDS THE PAST SEVERAL HOURS SHOW A SLOW DECAY OF THE
PRECIPITATION ACROSS IOWA/ILLINOIS. THIS MAY BE PARTLY DUE TO THE
MCS MOVING FROM NEBRASKA INTO KANSAS INTERCEPTING THE MOIST FLOW. AT
THE SAME TIME THE OVERALL CONVERGENCE AND MOISTURE TRANSPORT ACROSS
IOWA HAS WEAKENED ALONG THE FRONT.
BASED ON TRENDS FROM THE RAP AND OTHER MODELS...THE MCS...HEAVY RAIN
AND LIFT TOOLS SUGGEST A CONTINUED SLOW DECAY OF THE CONVECTION
ACROSS THE CWFA THROUGH SUNRISE AND THE MORNING COMMUTE. BY MID TO
LATE MORNING AND CONTINUING INTO EARLY AFTERNOON VERY LITTLE IF ANY
CONVECTION WILL BE SEEN DUE TO THE NOCTURNAL CONVECTIVE MINIMA.
DIURNAL CONVECTION WILL DEVELOP DURING THE AFTERNOON AS THE
CONVECTIVE TEMPERATURE IS ACHIEVED. HOWEVER...TRENDS FROM THE RAP
SUGGEST A MAJORITY OF THIS CONVECTION WILL BE GENERALLY SOUTH OF A
KOTM TO KSQI LINE AND REMAIN ISOLATED TO SCATTERED IN NATURE.
IF ANY CONVECTION SPILLS OVER INTO THE EVENING HOURS IT WILL QUICKLY
DISSIPATE WITH THE SETTING SUN. FROM MID EVENING THROUGH SUNRISE
TUESDAY...QUIET AND DRY CONDITIONS WILL BE SEEN AS THE NEXT HIGH
PRESSURE BEGINS BUILDING INTO THE MIDWEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 319 AM CDT MON AUG 12 2013
FLOW PATTERN ALOFT TO REMAIN NORTHWESTERLY AS AREA LOCATED BETWEEN
WESTERN CONUS RIDGE AND EASTERN TROUGH. AT THE SURFACE... LARGE
EXPANSE OF CANADIAN HIGH PRESSURE WILL BUILD INTO THE AREA THROUGH
MID-WEEK... THEN ONLY SLOWLY DRIFT INTO THE GREAT LAKES AND OHIO
VALLEY THIS WEEKEND ALL THE WHILE REMAINING THE DOMINANT WEATHER
FEATURE. THE RESULT WILL BE A PROLONGED STRETCH OF FANTASTIC
WEATHER FOR THE AREA FEATURING COOLER AND DRIER THAN NORMAL
CONDITIONS INTO NEXT WEEKEND. TUE NGT AND WED NGT LOOK TO BE THE
COOLEST OF THE STRETCH... WITH LOWS IN THE 40S LIKELY AT THE
TYPICAL COLD DRAINAGE SITES GIVEN PROGGED 850 MB TEMPS OF 7C TO 9C
AND CALM WINDS. IN ADDITION... SOME PATCHY RADIATIONAL FOG
POSSIBLE LATE TUE/WED NGTS IN THE RIVER VALLEYS AND OTHER LOW
LYING AREAS GIVEN SHALLOW STEEP LOW LEVEL INVERSION. TEMPS OVERALL
THOUGH MAINLY IN THE MID 70S TO LOWER 80S FOR HIGHS TUE-FRI AND
MAINLY IN THE 50S FOR LOWS. HAVE LOWERED MINS MOST PERIODS TUE
NGT-FRI NGT BY 1-2 DEGS BUT MAY NEED TO LOWER FURTHER AS CONTINUED
DRYING SHOULD AID IN EXPANDING DAILY DIURNAL RANGES... WITH LOWS
GENERALLY FAVORING NEAR OR BELOW THE COOL SIDE OF GUIDANCE AND
HIGHS NEAR BLEND OR TOWARD WARMER SIDE OF GUIDANCE. A SLOW WARMING
TREND ONLY TO AROUND NORMAL IS EXPECTED NEXT WEEKEND WITH 850 MB
TEMPS WARMING TO AROUND 12C TO 15C YIELDING HIGHS IN THE 80S.
BUT... EASTERLY SURFACE WINDS SHOULD ENSURE CONTINUED LOW HUMIDITY
LEVELS AND EXTREMELY COMFORTABLE CONDITIONS DESPITE THE MODERATION
IN TEMPS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1235 PM CDT MON AUG 12 2013
VFR/OCNL MVFR CIGS THIS AFTERNOON AS A COLD FRONT PUSHES INTO
SOUTHEAST IA. HAVE MENTIONED VCSH AT KBRL UNTIL 21Z/12. ELSEWHERE
WILL BE DRY WITH DECREASING CLOUDS. VFR CONDS TONIGHT AND TUESDAY
MORNING AS HIGH PRESSURE BEGINS TO BUILD INTO THE AREA FROM THE
NORTH. NORTHWEST WINDS AROUND 10 KNOTS THIS AFTERNOON THEN NORTH
TO NORTHEAST TONIGHT AND TUESDAY MORNING LESS THAN 10 KNOTS.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...HAASE
SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...HAASE
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1121 AM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 1120 AM CDT MON AUG 12 2013
COLD FRONT EXTENDED FROM NEAR FREEPORT TO THE QUAD CITIES TO JUST
SOUTH OF OTTUMWA AND WAS MOVING SOUTHEAST. ONLY ISOLATED SHOWERS
HAVE OCCURRED ALONG THE FRONT SO FAR WITH THE MAIN AREA OF
THUNDERSTORMS IN MISSOURI. RAPID REFRESH MESO MODEL INDICATES A
FEW SHOWERS AND THUNDERSTORMS WILL GRAZE OUR FAR SOUTHERN COUNTIES
THROUGH THE MID AFTERNOON HOURS AHEAD OF THE FRONT.
HAVE LOWERED TEMPERATURES A FEW DEGREES DUE TO EXTENSIVE CLOUD
COVER. HOWEVER...SKIES WERE CLEARING ACROSS NORTHERN AND WESTERN
IA AND NORTH INTO MN AS COOLER AND DRIER AIR FEED INTO THOSE AREAS.
UPDATE ISSUED AT 702 AM CDT MON AUG 12 2013
THE NOCTURNAL CONVECTION HAS DISSIPATED ACROSS THE AREA. TRENDS
FROM THE RAP INDICATE DOWNWARD MOTION HAS DEVELOPED SINCE MIDNIGHT
BEHIND A WEAK VORT MAX AND THIS DOWNWARD MOTION WILL PERSIST
THROUGH LATE MORNING.
THE MCS AND LIFT TOOLS GIVE MIXED SIGNALS ON THE POTENTIAL FOR
DIURNAL CONVECTION THIS AFTERNOON. IF CONVECTION DOES OCCUR...IT
WILL BE MAINLY ISOLATED TO POSSIBLY SCATTERED AND GENERALLY OVER
THE SOUTHEAST THIRD TO 40 PERCENT OF THE CWFA. TRENDS WITH THE RAP
MODEL SUGGEST ANY CONVECTION WILL BE NEARLY GONE ACROSS THE CWFA
BY EARLY EVENING. ..08..
&&
.SYNOPSIS...
ISSUED AT 319 AM CDT MON AUG 12 2013
06Z SFC ANALYSIS HAS A WEAK LOW WEST OF KMIW WITH A WARM FRONT TO
NEAR KCID. A COLD FRONT RAN FROM THE LOW INTO SOUTHERN NEBRASKA.
ANOTHER WEAK LOW WAS AT KLSE WITH A TROF CONNECTING THAT LOW WITH
THE LOW NEAR KMIW. DEW POINTS WERE IN THE 50S AND 60S ACROSS THE
MIDWEST WITH 70S ACROSS THE DEEP SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 319 AM CDT MON AUG 12 2013
RADAR TRENDS THE PAST SEVERAL HOURS SHOW A SLOW DECAY OF THE
PRECIPITATION ACROSS IOWA/ILLINOIS. THIS MAY BE PARTLY DUE TO THE
MCS MOVING FROM NEBRASKA INTO KANSAS INTERCEPTING THE MOIST FLOW. AT
THE SAME TIME THE OVERALL CONVERGENCE AND MOISTURE TRANSPORT ACROSS
IOWA HAS WEAKENED ALONG THE FRONT.
BASED ON TRENDS FROM THE RAP AND OTHER MODELS...THE MCS...HEAVY RAIN
AND LIFT TOOLS SUGGEST A CONTINUED SLOW DECAY OF THE CONVECTION
ACROSS THE CWFA THROUGH SUNRISE AND THE MORNING COMMUTE. BY MID TO
LATE MORNING AND CONTINUING INTO EARLY AFTERNOON VERY LITTLE IF ANY
CONVECTION WILL BE SEEN DUE TO THE NOCTURNAL CONVECTIVE MINIMA.
DIURNAL CONVECTION WILL DEVELOP DURING THE AFTERNOON AS THE
CONVECTIVE TEMPERATURE IS ACHIEVED. HOWEVER...TRENDS FROM THE RAP
SUGGEST A MAJORITY OF THIS CONVECTION WILL BE GENERALLY SOUTH OF A
KOTM TO KSQI LINE AND REMAIN ISOLATED TO SCATTERED IN NATURE.
IF ANY CONVECTION SPILLS OVER INTO THE EVENING HOURS IT WILL QUICKLY
DISSIPATE WITH THE SETTING SUN. FROM MID EVENING THROUGH SUNRISE
TUESDAY...QUIET AND DRY CONDITIONS WILL BE SEEN AS THE NEXT HIGH
PRESSURE BEGINS BUILDING INTO THE MIDWEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 319 AM CDT MON AUG 12 2013
FLOW PATTERN ALOFT TO REMAIN NORTHWESTERLY AS AREA LOCATED BETWEEN
WESTERN CONUS RIDGE AND EASTERN TROUGH. AT THE SURFACE... LARGE
EXPANSE OF CANADIAN HIGH PRESSURE WILL BUILD INTO THE AREA THROUGH
MID-WEEK... THEN ONLY SLOWLY DRIFT INTO THE GREAT LAKES AND OHIO
VALLEY THIS WEEKEND ALL THE WHILE REMAINING THE DOMINANT WEATHER
FEATURE. THE RESULT WILL BE A PROLONGED STRETCH OF FANTASTIC
WEATHER FOR THE AREA FEATURING COOLER AND DRIER THAN NORMAL
CONDITIONS INTO NEXT WEEKEND. TUE NGT AND WED NGT LOOK TO BE THE
COOLEST OF THE STRETCH... WITH LOWS IN THE 40S LIKELY AT THE
TYPICAL COLD DRAINAGE SITES GIVEN PROGGED 850 MB TEMPS OF 7C TO 9C
AND CALM WINDS. IN ADDITION... SOME PATCHY RADIATIONAL FOG
POSSIBLE LATE TUE/WED NGTS IN THE RIVER VALLEYS AND OTHER LOW
LYING AREAS GIVEN SHALLOW STEEP LOW LEVEL INVERSION. TEMPS OVERALL
THOUGH MAINLY IN THE MID 70S TO LOWER 80S FOR HIGHS TUE-FRI AND
MAINLY IN THE 50S FOR LOWS. HAVE LOWERED MINS MOST PERIODS TUE
NGT-FRI NGT BY 1-2 DEGS BUT MAY NEED TO LOWER FURTHER AS CONTINUED
DRYING SHOULD AID IN EXPANDING DAILY DIURNAL RANGES... WITH LOWS
GENERALLY FAVORING NEAR OR BELOW THE COOL SIDE OF GUIDANCE AND
HIGHS NEAR BLEND OR TOWARD WARMER SIDE OF GUIDANCE. A SLOW WARMING
TREND ONLY TO AROUND NORMAL IS EXPECTED NEXT WEEKEND WITH 850 MB
TEMPS WARMING TO AROUND 12C TO 15C YIELDING HIGHS IN THE 80S.
BUT... EASTERLY SURFACE WINDS SHOULD ENSURE CONTINUED LOW HUMIDITY
LEVELS AND EXTREMELY COMFORTABLE CONDITIONS DESPITE THE MODERATION
IN TEMPS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 702 AM CDT MON AUG 12 2013
VFR WX IS EXPECTED THROUGH 06Z/13. KMLI/KBRL MAY SEE VCSH OR VCTS
IN THE 18Z/12 TO 01Z/13 TIME FRAME BUT THE PROBABILITY IS 15
PERCENT OR LESS. AFT 06Z/13 VFR WX IS GENERALLY EXPECTED TO
CONTINUE BUT SOME PATCHY SHALLOW FOG MAY OCCUR DUE TO CLEAR SKIES
AND LIGHT WINDS. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...HAASE
SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
718 AM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 702 AM CDT MON AUG 12 2013
THE NOCTURNAL CONVECTION HAS DISSIPATED ACROSS THE AREA. TRENDS
FROM THE RAP INDICATE DOWNWARD MOTION HAS DEVELOPED SINCE MIDNIGHT
BEHIND A WEAK VORT MAX AND THIS DOWNWARD MOTION WILL PERSIST
THROUGH LATE MORNING.
THE MCS AND LIFT TOOLS GIVE MIXED SIGNALS ON THE POTENTIAL FOR
DIURNAL CONVECTION THIS AFTERNOON. IF CONVECTION DOES OCCUR...IT
WILL BE MAINLY ISOLATED TO POSSIBLY SCATTERED AND GENERALLY OVER
THE SOUTHEAST THIRD TO 40 PERCENT OF THE CWFA. TRENDS WITH THE RAP
MODEL SUGGEST ANY CONVECTION WILL BE NEARLY GONE ACROSS THE CWFA
BY EARLY EVENING. ..08..
&&
.SYNOPSIS...
ISSUED AT 319 AM CDT MON AUG 12 2013
06Z SFC ANALYSIS HAS A WEAK LOW WEST OF KMIW WITH A WARM FRONT TO
NEAR KCID. A COLD FRONT RAN FROM THE LOW INTO SOUTHERN NEBRASKA.
ANOTHER WEAK LOW WAS AT KLSE WITH A TROF CONNECTING THAT LOW WITH
THE LOW NEAR KMIW. DEW POINTS WERE IN THE 50S AND 60S ACROSS THE
MIDWEST WITH 70S ACROSS THE DEEP SOUTH.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 319 AM CDT MON AUG 12 2013
RADAR TRENDS THE PAST SEVERAL HOURS SHOW A SLOW DECAY OF THE
PRECIPITATION ACROSS IOWA/ILLINOIS. THIS MAY BE PARTLY DUE TO THE
MCS MOVING FROM NEBRASKA INTO KANSAS INTERCEPTING THE MOIST FLOW. AT
THE SAME TIME THE OVERALL CONVERGENCE AND MOISTURE TRANSPORT ACROSS
IOWA HAS WEAKENED ALONG THE FRONT.
BASED ON TRENDS FROM THE RAP AND OTHER MODELS...THE MCS...HEAVY RAIN
AND LIFT TOOLS SUGGEST A CONTINUED SLOW DECAY OF THE CONVECTION
ACROSS THE CWFA THROUGH SUNRISE AND THE MORNING COMMUTE. BY MID TO
LATE MORNING AND CONTINUING INTO EARLY AFTERNOON VERY LITTLE IF ANY
CONVECTION WILL BE SEEN DUE TO THE NOCTURNAL CONVECTIVE MINIMA.
DIURNAL CONVECTION WILL DEVELOP DURING THE AFTERNOON AS THE
CONVECTIVE TEMPERATURE IS ACHIEVED. HOWEVER...TRENDS FROM THE RAP
SUGGEST A MAJORITY OF THIS CONVECTION WILL BE GENERALLY SOUTH OF A
KOTM TO KSQI LINE AND REMAIN ISOLATED TO SCATTERED IN NATURE.
IF ANY CONVECTION SPILLS OVER INTO THE EVENING HOURS IT WILL QUICKLY
DISSIPATE WITH THE SETTING SUN. FROM MID EVENING THROUGH SUNRISE
TUESDAY...QUIET AND DRY CONDITIONS WILL BE SEEN AS THE NEXT HIGH
PRESSURE BEGINS BUILDING INTO THE MIDWEST.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 319 AM CDT MON AUG 12 2013
FLOW PATTERN ALOFT TO REMAIN NORTHWESTERLY AS AREA LOCATED BETWEEN
WESTERN CONUS RIDGE AND EASTERN TROUGH. AT THE SURFACE... LARGE
EXPANSE OF CANADIAN HIGH PRESSURE WILL BUILD INTO THE AREA THROUGH
MID-WEEK... THEN ONLY SLOWLY DRIFT INTO THE GREAT LAKES AND OHIO
VALLEY THIS WEEKEND ALL THE WHILE REMAINING THE DOMINANT WEATHER
FEATURE. THE RESULT WILL BE A PROLONGED STRETCH OF FANTASTIC
WEATHER FOR THE AREA FEATURING COOLER AND DRIER THAN NORMAL
CONDITIONS INTO NEXT WEEKEND. TUE NGT AND WED NGT LOOK TO BE THE
COOLEST OF THE STRETCH... WITH LOWS IN THE 40S LIKELY AT THE
TYPICAL COLD DRAINAGE SITES GIVEN PROGGED 850 MB TEMPS OF 7C TO 9C
AND CALM WINDS. IN ADDITION... SOME PATCHY RADIATIONAL FOG
POSSIBLE LATE TUE/WED NGTS IN THE RIVER VALLEYS AND OTHER LOW
LYING AREAS GIVEN SHALLOW STEEP LOW LEVEL INVERSION. TEMPS OVERALL
THOUGH MAINLY IN THE MID 70S TO LOWER 80S FOR HIGHS TUE-FRI AND
MAINLY IN THE 50S FOR LOWS. HAVE LOWERED MINS MOST PERIODS TUE
NGT-FRI NGT BY 1-2 DEGS BUT MAY NEED TO LOWER FURTHER AS CONTINUED
DRYING SHOULD AID IN EXPANDING DAILY DIURNAL RANGES... WITH LOWS
GENERALLY FAVORING NEAR OR BELOW THE COOL SIDE OF GUIDANCE AND
HIGHS NEAR BLEND OR TOWARD WARMER SIDE OF GUIDANCE. A SLOW WARMING
TREND ONLY TO AROUND NORMAL IS EXPECTED NEXT WEEKEND WITH 850 MB
TEMPS WARMING TO AROUND 12C TO 15C YIELDING HIGHS IN THE 80S.
BUT... EASTERLY SURFACE WINDS SHOULD ENSURE CONTINUED LOW HUMIDITY
LEVELS AND EXTREMELY COMFORTABLE CONDITIONS DESPITE THE MODERATION
IN TEMPS.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 702 AM CDT MON AUG 12 2013
VFR WX IS EXPECTED THROUGH 06Z/13. KMLI/KBRL MAY SEE VCSH OR VCTS
IN THE 18Z/12 TO 01Z/13 TIME FRAME BUT THE PROBABILITY IS 15
PERCENT OR LESS. AFT 06Z/13 VFR WX IS GENERALLY EXPECTED TO
CONTINUE BUT SOME PATCHY SHALLOW FOG MAY OCCUR DUE TO CLEAR SKIES
AND LIGHT WINDS. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...05
AVIATION...08
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
600 AM CDT Mon Aug 12 2013
...Update to aviation for 12Z TAFs...
.SYNOPSIS...
ISSUED AT 343 AM CDT MON AUG 12 2013
The hemispheric scale general circulation has not changed much over
the past couple of days as a large Hudson Bay gyre continues to
influence sensible weather across much of eastern Canada and the
adjacent northeastern CONUS. A ridge of high pressure in the
mid-upper troposphere was centered across the Rockies while a
slow-moving upper low was moving north along the Pacific Northwest
coast. RAOB and RAP analysis continued to indicate a strong
subtropical jet at or just south of 30N latitude from well off the
southern California coast into Arizona and northern New Mexico.
Nocturnal water vapor loop shows a substantial mid level drying
signature tied to this jet which is disrupting the monsoonal flow
pattern across the Desert Southwest. On the mesoscale, a weak
shortwave trough moving through the Central Plains spawned the
development of a couple of mesoscale convective systems (MCS)...the
largest being across north-central Kansas. Another smaller MCS was
located across far south-central Kansas. The stronger, northern MCS
had some low level frontogenesis to aid in deeper tropospheric
upward vertical motion.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 343 AM CDT MON AUG 12 2013
The very weak frontal boundary, which promoted the development and
sustainment of the MCS across northern Kansas, will continue its
slow push into southwest Kansas through mid-morning Monday. The
front is difficult to identify on a surface chart with winds up in
Nebraska either calm or some very light variation of east...and the
MSLP gradient is very weak as well. Nevertheless, the MCS and its
outflow boundary (OFB) will provide additional convergence with the
OFB likely bisecting the southwest Kansas region by midday. None of
the convective-allowing models are showing much in the way of
thunderstorm redevelopment back across southwest Kansas this
afternoon where the remnant OFB will have likely stalled out. That
being said, the 00z and now the latest 06z run of the NAM12 do show
a more favorable QPF signal in the low level convergence zone across
southwest Kansas in the 21-00z time frame later on today. I tend to
lean more toward the NAM12 given that the lower troposphere is
fairly moist, there will be boundary layer convergence, and a
capping inversion that is not overly strong. The Storm Prediction
Center slight-risk for severe storms is focused from southwest
Kansas into northeastern Oklahoma and I cannot argue with this
forecast. Should storms form on the old front/OFB as I think they
will, then organized multi-cell or even a supercell storm could
exist given strong upper tropospheric flow (250mb winds of
65-75kts). Large hail to half-dollars and damaging wind gusts to 65
mph seem to be the best prediction for maximum severe threats in
this setup later this afternoon/evening. It is unclear how the heavy
rain threat will play out...as there will likely be another MCS
thriving during the late evening and eventually the overnight
hours...however it is extremely difficult to predict how large of an
MCS there will be and where exactly it will focus on. The most
likely location would be between the Arkansas River and the Oklahoma
border and east of Highway 83. We will not issue any flood/flash
flood headline at this time given too much uncertainty/low
confidence in the risk.
.LONG TERM...(Tuesday through Sunday)
ISSUED AT 343 AM CDT MON AUG 12 2013
Tuesday:
Large uncertainty exists Tuesday spatiotemporally with MCS activity.
The ECMWF has been persistent over the last few nights in
advertising a decent convective/QPF signal across SW Kansas. Upslope
flow from the sfc to 850 hPa, along with copious boundary layer
moisture will set the stage for decent precip event across the
region. The GFS/GEM also show MCS activity marching across the
Kansas prairies through the day. The NAM has been consistent in a
much drier solution with little in the way of precipitation. To
further uncertainty, the 4 km nested NAM is in agreement (different
cp schemes) with the operational NAM. The two cores of the WRF are
in between the global and aforementioned mesoscale models. Given the
fact that precipitable water values are forecasted to between the
75th percentile to +2SD, will keep with likely precipitation
probability percentage points. Now is not the time to be
conservative with precipitation chances, since we are dealing with a
moist and unstable atmosphere. Heavy rain will be possible as well.
Went with ECE guidance for temperatures, which shows maximums around
the 80F mark. Minimums for Wednesday morning look to be in the 60sF.
Wednesday:
With northwesterly flow aloft and low level upslope flow continuing
Wednesday, we could see diurnal thunderstorm activity. Will go with
chance precipitation probability percentage points for now with a
bias towards the ECMWF solution. Wednesdays activity should be more
isolated, and the resultant threat for heavy rain will be isolated
as well. Maximums will be pleasant and in the upper 70sF. Lows still
in the 60sF for Thursday morning.
Thursday and beyond:
Will stick with the weighted allblend solution for the rest of the
period as uncertainty continues. The bottom line is that there will
be bouts of convection thru Saturday. The forecast could be dry
Sunday, as a 500 hPa ridge extends eastward with resultant
increasing geopotential heights and a dry northerly flow aloft.
Highs should moderate to near normal by next weekend. With all the
uncertainty in the extended, we`ll tread lightly.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 600 AM CDT MON AUG 12 2013
VFR cigs expected through much of TAF pd. MVFR cigs possible this
evening in association with low clouds. Convection is possible this
afternoon and evening, but due to low confidence in model solutions,
will leave out for now.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 89 67 80 62 / 40 60 60 60
GCK 86 66 79 64 / 50 60 60 60
EHA 89 67 79 61 / 40 50 60 60
LBL 90 68 79 64 / 40 50 60 60
HYS 85 67 79 60 / 30 60 40 40
P28 90 70 82 65 / 40 60 60 60
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...UMSCHEID
SHORT TERM...UMSCHEID
LONG TERM...Sugden
AVIATION...Sugden
AREA FORECAST DISCUSSION
NWS PADUCAH KY
241 PM CDT Mon Aug 12 2013
.SHORT TERM...(This Evening through Tuesday Night)
ISSUED AT 1250 PM CDT MON AUG 12 2013
It looks like the blended model approach is too slow. It lingers
pops well after fropa into/thru Tuesday. We went with the HRRR and
Nam`s more meso type solutions, which had higher resolution and
initiated well. It has higher pops but departs them more quickly
with fropa and with the aforementioned finer resolution. It models
the initial environment well, so we at least are hoping for a nice
0-6 hr init with a transition toward the Nam in the overall pop
modeling thru Tuesday. Alot will be told here with how the
remainder of the pm/into the early evening goes. Should see fairly
active/high concentration convection to continue breaking out in
moist/unstable air ahead of incoming front/energy this pm-
evening...to sweep southward with time/with perhaps additional
development along main front as well as outflow boundaries thru
the overnight hours. Meso models take the front thru tonight and
start to usher in the drier air at the lower levels late tonight-
early tmrw, which should preclude pop mention. We`ll watch closely
and also see about collab as to whether to remove pop altogetheror
leave lingering Tuesday pop. Certainly by Tue evening-overnight
all models are in agreement that the drier dew points are working
thru the column and we poise for the nice pleasant cooler/drier
air to take root from mid week on.
.LONG TERM /Wednesday through Monday/...
ISSUED AT 215 PM CDT MON AUG 12 2013
Unusually high amplitude flow pattern for the middle of August will
continue...with a large ridge in the west and a deep trough in the
Mississippi and Ohio Valley regions. The trough is forecast to
weaken late in the period /Monday/...which will result in some
semblance of a typical August pattern.
As far as the daily details...
An unseasonably strong /1023 mb/ surface high will progress slowly
east across the Great Lakes and upper Midwest Wednesday through
Thursday. This high will funnel a cool and dry air mass
southward...with 850 mb temps ranging from 10 to 12 for much of the
period. These 850 mb temps support highs only in the upper 70s with
full sun. Overnight lows will be in the lower to mid 50s. Generally
followed the cooler NAM mos for low temps...though the difference
between NAM and GFS mos is negligible in some places. It should be
noted that 850 mb temp anomalies Wed/Thu will be 2 to 3 standard
deviations below normal. The air mass will also be very dry. Model
soundings suggest nothing more than a few pancake cumulus clouds
each afternoon.
On Friday and Friday night...an inverted surface trough will
retrograde westward across the Tennessee Valley as a 500 mb
shortwave digs southeast into the Mississippi Valley. It will take a
while for the atmosphere to moisten up...so only the far southeast
counties /KHOP area/ nearest the surface trough are at risk of any
precip.
Saturday through Sunday...the upper trough will be nearly overhead.
Some guidance indicates the trough will close off into an upper low
over our region. At low levels...the inverted trough will take up
residence near or just south of our region. Dew point pooling along
the surface trough will bring dew points up through the 60s. Precip
water values are forecast to climb steadily to between 1.5 and 2
inches by Sunday /GFS model/. The models are considerably more
unstable than they were yesterday...so will add mention of thunder
for the weekend. Pops will be in the chance category in most areas
for Sunday. Most of the precip should be diurnally driven
convection.
On Monday...the upper trough is forecast to weaken and/or lift
northeast. The surface trough will dissipate...leaving only a
weakly cyclonic east to southeast flow. Precip chances will begin to
diminish from the west. Temps and humidity will gradually approach
climo.
&&
.AVIATION...
ISSUED AT 1250 PM CDT MON AUG 12 2013
MVFR cigs are prevalent as daytime heating bases in the 1500-2500
ft agl range abound. Above these decks when they temporarily
scatter is low VFR cigs in the 3500-4000 feet range with layered
higher based clouds still. Active diurnal convection will affect
KEVV/KOWB first, but all sites will develop showers/storms this
evening as front sags south. This will continue thru the overnight
hours with MVFR conditions prevailing and a small chance of IFR
cigs/vsbys in a thunderstorm. By the planning period tomorrow
morning, fropa should occur and skies should be diminishing in
clouds as a return to VFR conditions is anticipated.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
Short term/aviation...DH
Long term...MY
AREA FORECAST DISCUSSION
NWS PADUCAH KY
100 PM CDT Mon Aug 12 2013
.SHORT TERM...(This Evening through Tuesday Night)
ISSUED AT 1250 PM CDT MON AUG 12 2013
It looks like the blended model approach is too slow. It lingers
pops well after fropa into/thru Tuesday. We went with the HRRR and
Nam`s more meso type solutions, which had higher resolution and
initiated well. It has higher pops but departs them more quickly
with fropa and with the aforementioned finer resolution. It models
the initial environment well, so we at least are hoping for a nice
0-6 hr init with a transition toward the Nam in the overall pop
modeling thru Tuesday. Alot will be told here with how the
remainder of the pm/into the early evening goes. Should see fairly
active/high concentration convection to continue breaking out in
moist/unstable air ahead of incoming front/energy this pm-
evening...to sweep southward with time/with perhaps additional
development along main front as well as outflow boundaries thru
the overnight hours. Meso models take the front thru tonight and
start to usher in the drier air at the lower levels late tonight-
early tmrw, which should preclude pop mention. We`ll watch closely
and also see about collab as to whether to remove pop altogetheror
leave lingering Tuesday pop. Certainly by Tue evening-overnight
all models are in agreement that the drier dew points are working
thru the column and we poise for the nice pleasant cooler/drier
air to take root from mid week on.
.LONG TERM...(Wednesday Night through Sunday)
ISSUED AT 349 AM CDT MON AUG 12 2013
The main feature of interest beginning this period will continue to
be unseasonably strong high pressure that will stretch from the
Great Lakes region east to the Mid Atlantic coast. Unseasonably cool
and dry northeast flow will remain in place Thursday and Friday.
However, a mid/upper level trof of low pressure will slowly develop
and dig southeast into the mid MS River Valley Friday night...before
becoming nearly stationary next weekend. Guidance has been
consistent in showing an inverted surface trough forming in response
to the mid lvl troffing. Moisture associated with these features
will bring an increase in clouds...and also possibly spawn scattered
showers east of the MS River next weekend. At this point, it looks
like the atmosphere will be too stable to warrant a mention of
thunder...and the increased cloud cover will delay any appreciable
warming trend.
&&
.AVIATION...
ISSUED AT 1250 PM CDT MON AUG 12 2013
MVFR cigs are prevalent as daytime heating bases in the 1500-2500
ft agl range abound. Above these decks when they temporarily
scatter is low VFR cigs in the 3500-4000 feet range with layered
higher based clouds still. Active diurnal convection will affect
KEVV/KOWB first, but all sites will develop showers/storms this
evening as front sags south. This will continue thru the overnight
hours with MVFR conditions prevailing and a small chance of IFR
cigs/vsbys in a thunderstorm. By the planning period tomorrow
morning, fropa should occur and skies should be diminishing in
clouds as a return to VFR conditions is anticipated.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
700 AM EDT MON AUG 12 2013
.UPDATE...
ISSUED AT 650 AM EDT MON AUG 12 2013
HAVE UPDATED THE FORECAST PRIMARILY TO FINE TUNE POPS AND WX THROUGH
THE CUMBERLAND VALLEY EARLY THIS MORNING IN RESPONSE TO THE CURRENT
RADAR AND TRENDS. ALSO TWEAKED THE MORNING LOWS IN THE GRIDS ALONG
WITH THE T/TD GRIDS...AND THEIR DIURNAL CURVE...FOR THE NEXT SEVERAL
HOURS. INDICATIONS ARE THAT THE FOG REMAINS DENSE IN PLACES NORTH OF
JKL WITH SOME DENSE PATCHES IN THE SOUTH...TOO...THOUGH THE ARRIVAL
OF LOWER CLOUDS AND CONVECTION HAS HELPED TO MIX THE AIR AND LIMIT
THE FOG NEAR THE TENNESSEE BORDER. WILL KEEP THE ADVISORY GOING FOR
NOW. UPDATES HAVE BEEN SENT TO THE NDFD AND WEB SERVERS.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 330 AM EDT MON AUG 12 2013
06Z SFC ANALYSIS SHOWS THE FRONTAL BOUNDARY NOW LYING WEST TO EAST
THROUGH THE SOUTHERN TIER OF THE CWA. THIS SHOWS UP IN THE LATEST
RADAR DATA...AS WELL...WITH SIGNS OF CONVECTION ALONG IT IN EAST
KENTUCKY AND SHOWERS POPPING NEARBY THROUGH CENTRAL KENTUCKY. NORTH
OF THE BOUNDARY...CIGS HAVE CLEARED OUT AND THIS HAS ALLOWED
WIDESPREAD FOG TO FORM WITH REPORTS OF IT LOCALLY DENSE IN MANY OF
THE VALLEYS NORTH OF JKL. FOR THIS REASON...AND THE EXPECTATION OF AT
LEAST PATCHY DENSE FOG IN THE SOUTHERN VALLEYS BY DAWN...A DENSE FOG
ADVISORY IS IN EFFECT THROUGH EAST KENTUCKY UNTIL 10 AM. JUST A HINT
OF A NORTH TO SOUTH TEMPERATURE AND DEWPOINT GRADIENT EXISTS ACROSS
THE BOUNDARY. T/TD ARE CURRENTLY IN THE UPPER 60S NORTH OF THE
MOUNTAIN PARKWAY...WITH VALUES IN THE LOWER 70S TO THE SOUTH.
THE MODELS ARE IN GOOD AGREEMENT ALOFT...AT LEAST LOCALLY...THROUGH
THE SHORT TERM AS THEY ALL DEPICT A DEEP TROUGH NORTH OF THE GREAT
LAKES AND STOUT RIDGING OVER THE DEEP SOUTH. NEAR ZONAL FLOW ALONG
THE OHIO RIVER WILL BRING SHORTWAVES ALONG WITH IT. A MORE DECENT ONE
WILL BE COMING OUT OF THE HIGH PLAINS AND START TO IMPACT EAST
KENTUCKY LATER TODAY...PASSING THROUGH TONIGHT. THIS WAVE WILL HELP
TO DRAG THE LARGER TROUGH FURTHER SOUTH INTO THE DAY TUESDAY WITH
SOME HEIGHT FALLS BY EVENING. ONCE AGAIN...THE MORE MESOSCALE
DETAILS PRIMARILY WILL GUIDE THE WEATHER THROUGH TUESDAY.
ACCORDINGLY...HAVE LEANED TOWARD THE NAM12 WITH SOME BOLSTERING OF
ITS SOLUTION FROM THE LATEST ECMWF...AND IN THE NEAR TERM...THE
CURRENT HRRR RUN.
SENSIBLE WEATHER WILL FEATURE A FOGGY START TO THE DAY FOR MOST OF
THE AREA. THE FOG WILL BURN OFF BY 10 AM AND THEN EXPECT THE NEXT
ROUND OF SHOWERS AND THUNDERSTORMS TO MOVE INTO THE CWA FROM THE
SOUTHWEST IN CONJUNCTION WITH ANOTHER RIPPLE ALONG THE STALLED
FRONT. THIS ONE WILL HAVE SOME DECENT UPPER LEVEL SUPPORT AND PLENTY
OF MOISTURE ALONG THE FRONT...SO HEAVY RAINFALL WILL REMAIN A THREAT
INTO TUESDAY MORNING...SOMETHING WE WILL HIGHLIGHT IN THE HWO. EXPECT
SOME PATCHY FOG AGAIN TONIGHT AND THEN A NORTH TO SOUTH DIMINISHING
TREND TO THE CONVECTION WITH TIME ON TUESDAY AS THE DEEPER MOISTURE
FROM FRONT STARTS TO MOVE SOUTH. TEMPS WILL BE IN THE LOWER 80S
TODAY AS THE ARRIVING CONVECTION...AND MORNING FOG...LIMIT THE RISE.
THEY LOOK EVEN COOLER TUESDAY WITH THAT FRONT AND ITS SHOWERS/TSTORMS
DROPPING SOUTH...TONIGHT WILL STILL BE RATHER WARM AND MUGGY...
THOUGH.
USED THE CONSSHORT AS A STARTING POINT FOR WINDS AND DEWPOINTS
THROUGH 24 HOURS...THEN CONSALL THEREAFTER. WITH TEMPS...FAVORED
THE CONSALL FOR MAX AND MIN VALUES ALONG WITH ITS DERIVED DIURNAL
CURVE. AS FOR POPS...HAVE ENDED UP CLOSER TO THE VERY WET MET NUMBERS
TODAY AND THEN AT OR SLIGHTLY LOWER THAN A MET/MAV CONSENSUS ON
TUESDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 250 AM EDT MON AUG 12 2013
AN AMPLIFIED 50H PATTERN WITH A RIDGE OVER THE ROCKIES AND A TROF
OVER THE ERN CONUS. AT THE SFC...HIGH PRESSURE OVER THE NRN PLAINS
WILL CONTINUE TO PUSH THE COLD FRONT FURTHER TO THE SOUTH WITH DRIER
AIR INFILTRATING THE COMMONWEALTH. THIS PATTERN WILL LEAD TO A MOSTLY
DRY FCST FOR MUCH OF ERN KY UNTIL THE END OF THE WEEK. BY FRI
MORNING AN INVERTED TROF AT THE SFC WILL ALLOW MOISTURE TO CREEP
INTO THE AREA AND DAY TIME HEATING COULD SPARK A FEW SHOWERS. EVEN
AS THIS IS HAPPENING...AT THE 50H LEVEL A VORT MAX IS DROPPING INTO
THE CNTRL PLAINS TO REINFORCE THE ERN TROF. THIS VORT MAX WILL
DEVELOP OVER THE WEEKEND INTO A CLOSED LOW AS THE SFC HIGH PRESSURE
SLIPS TO NEW ENG AND ALLOWS ADDITIONAL MOISTURE TO INVADE THE REGION
WITH A GOOD CHANCE OF PRECIP.
WITH THE HIGH PRESSURE FILTERING COOLER AIR INTO THE AREA...EXPECT
HIGH TEMPS IN THE UPPER 70S FOR WED AND THU BEFORE THE RETURNING
SOUTHERLY FLOW CAN BOOST HIGHS INTO THE LOWER 80S BY FRI. 80S WILL
CONTINUE INTO SAT BEFORE THE EXPECTED PCPN WILL RESTRICT HIGHS BACK
TO AROUND 80 FOR SUN AND THE UPPER 70S FOR MON.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 700 AM EDT MON AUG 12 2013
FOG REMAINS A PROBLEM EARLY THIS MORNING AT THE JKL SITE WHERE VLIFR
CONDITIONS ARE HOLDING. FURTHER SOUTH...THE FOG IS MORE VARIABLE AND
LIGHTER DUE TO LOW AND MID LEVEL CLOUDS MOVING IN WITH THE NEXT BATCH
OF CONVECTION CROSSING INTO THE CUMBERLAND VALLEY. STILL EXPECT ALL
THE FOG TO CLEAR BETWEEN 13 AND 14Z. THEN WE WILL LIKELY SEE BETTER
COVERAGE OF SHOWERS AND THUNDERSTORMS ACROSS SOUTHWEST PARTS OF THE
AIR FIRST...EXPANDING TO COVER THE REST EAST KENTUCKY AROUND OR
SHORTLY AFTER 16Z. CONTINUED THE VCTS IN THE TAFS BEFORE GOING TO
STRAIGHT UP TSRA PREVAILING BY MID AFTERNOON AT LOZ AND SME. WOULD
ANTICIPATE A LULL IN THE MORE CONCENTRATED CONVECTION THIS EVENING
BEFORE ANOTHER BAND MAY RAMP UP LATE TONIGHT. HAVE TRIED TO TIME THIS
IN KEEPING WITH THE PUBLIC FORECAST FOR TONIGHT. AWAY FROM ANY
STORMS...WINDS WILL BE LIGHT AND VARIABLE THROUGH THE PERIOD.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ044-
050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...GREIF
SHORT TERM...GREIF
LONG TERM...DUSTY
AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
105 PM CDT Mon Aug 12 2013
.UPDATE:
Issued at 847 AM CDT Mon Aug 12 2013
Made some smap adjustments to pops and temperatures for today. The
cluster of storms moving into central missouri seems to be living
longer than previously thought, so have increased pops to likely
generally along the i-70 corridor in central and parts of eastern
misouri and lowered highs today in that same region. Not sure how
much longer the cluster will last, but 850mb RUC continues to show
good moisture convergence into the afternoon as a weak low level
jet continues to veer. Will continue to monitor and update as the
stoms evolve.
Carney
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 337 AM CDT Mon Aug 12 2013
07Z surface analysis revealed three boundaries of interest across
the region. First, a warm front was lifting northward through
central and southeastern MO. WAA with this boundary was contributing
to isolated showers/thunderstorms early this morning across
southeastern MO and extreme southern IL. Second, active convection
had generated an outflow boundary across portions of KS/NE/IA.
Third, a synoptic cold front was moving southward through SD/MN.
None of these features is especially strong, and model forecasts
suggest that the warmer air behind the warm front will simply
reinforce the broader baroclinic zone. Another way to look at it is
that the aforementioned boundaries will fall into the same broad
pressure trough which stretches from KS to WI. Regardless, H7-H5
lapse rates of around 6 deg C/km along with up to 1000 J/kg of CAPE
ahead of an advancing cold front should be sufficient for scattered
thunderstorms, especially during the afternoon and early evening
hours.
Kanofsky
.LONG TERM: (Tonight through Sunday)
Issued at 337 AM CDT Mon Aug 12 2013
Thunderstorm threat should persist across most of the CWA tonight,
but am beginning to think that primary threat may be during the
evening and be associated with "leftover" convection from the
afternoon hours. Airmass is progged to stabilize quite a bit during
the evening and convergence along ill-defined front becomes almost
non-existent after 06z, so almost all UVV will come from weak
shortwave energy dropping across the area. Have gone ahead and
dropped the POPs in our far N counties after 06z with passage of the
cold front.
Concern also remains for precipitation chances on Tuesday. There is
better agreement in the 00z runs pointing to active convection
working across SW MO during the morning. While the POP/QPF bullseye
with this activity should be well southwest of our CWA, primary
question is if and/or how much of this activity will be able to work
into our CWA as it shears off to the southeast with the slowly
increasing NW mid level flow. For now I have held onto slight
chance POPs as far north as a COU-SAR line for the morning hours;
this still may be too far north but will wait for today`s model runs
to confirm this above thinking before making additional cuts to
POPs.
For the remainder of the week, medium range solutions are still
indicating that a series of shortwaves rotating around upper low
over southeast Canada will lower heights over the eastern CONUS.
This shift in the UA pattern will allow Canadian high pressure to
build into, and then become locked over, the mid-Mississippi Valley.
The net result should be several days of dry and relatively cool
August weather. There has been little run-to-run change in the
progged temperature profile across the region during this time, so
it still looks like temperatures in the Wednesday-Friday time frame
will be averaging 5-10 degrees below normal. Progged 850mb temps as
well as MOS guidance suggests highs in the 75-80 degree range, with
lows primarily in the 50s.
00z GFS and ECMWF are still hinting at a secondary shortwave
dropping into the mid-Mississippi valley and developing a cut-off
low in the vicinity of the lower Ohio valley heading into the
weekend. This certainly bears watching, but latest guidance
suggests that primary moisture surge, and precipitation threat, will
be ahead of this feature, and primarily east of our CWA. So for
now have maintained a dry forecast for the weekend, with gradual
modification of the airmass allowing for a slow warming trend.
Truett
&&
.AVIATION: (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1252 PM CDT Mon Aug 12 2013
Primary concern continues to be thunderstorms moving across the
area. While the majority of the area remains vfr, a swath of low
mvfr and ifr conditions associated with the storms will move east-
southeast at around 25 mph. expect that the storms will clear our
eastern/southeastern zones by 00z this evening. northerly flow
will freshen this evening and overnight which will bring in some
drier air. however, the sky is expected to clear out and am unsure
what the fog potential will be as the drier air filters in. think
the greatest potential for fog will be along and south of the I-70
corridor where it rained and the driest air will not penetrate
tonight.
Specifics for KSTL:
Expect showers and thunderstorms to continue at Lambert through
19Z or so. Intermittant IFR vsbys in moderate rain are possible
until the rain clears the terminal. intermittant showers are
possible the remainder of the afternoon. expect the sky to clear
overnight, but there is the potential for fog late. a northerly
wind will bring drier air into the region, but am not sure how
much drying there will be with persistent cloud cover until late
this afternoon and the northerly flow staying fairly light. while
there`s no mention in the taf right now, mvfr or even ifr fog may
be possible. will pass these thoughts along to the next shift to
reevaluate.
Carney
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
852 AM CDT Mon Aug 12 2013
.UPDATE:
Issued at 847 AM CDT Mon Aug 12 2013
Made some smap adjustments to pops and temperatures for today. The
cluster of storms moving into central missouri seems to be living
longer than previously thought, so have increased pops to likely
generally along the i-70 corridor in central and parts of eastern
misouri and lowered highs today in that same region. Not sure how
much longer the cluster will last, but 850mb RUC continues to show
good moisture convergence into the afternoon as a weak low level
jet continues to veer. Will continue to monitor and update as the
stoms evolve.
Carney
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 337 AM CDT Mon Aug 12 2013
07Z surface analysis revealed three boundaries of interest across
the region. First, a warm front was lifting northward through
central and southeastern MO. WAA with this boundary was contributing
to isolated showers/thunderstorms early this morning across
southeastern MO and extreme southern IL. Second, active convection
had generated an outflow boundary across portions of KS/NE/IA.
Third, a synoptic cold front was moving southward through SD/MN.
None of these features is especially strong, and model forecasts
suggest that the warmer air behind the warm front will simply
reinforce the broader baroclinic zone. Another way to look at it is
that the aforementioned boundaries will fall into the same broad
pressure trough which stretches from KS to WI. Regardless, H7-H5
lapse rates of around 6 deg C/km along with up to 1000 J/kg of CAPE
ahead of an advancing cold front should be sufficient for scattered
thunderstorms, especially during the afternoon and early evening
hours.
Kanofsky
.LONG TERM: (Tonight through Sunday)
Issued at 337 AM CDT Mon Aug 12 2013
Thunderstorm threat should persist across most of the CWA tonight,
but am beginning to think that primary threat may be during the
evening and be associated with "leftover" convection from the
afternoon hours. Airmass is progged to stabilize quite a bit during
the evening and convergence along ill-defined front becomes almost
non-existent after 06z, so almost all UVV will come from weak
shortwave energy dropping across the area. Have gone ahead and
dropped the POPs in our far N counties after 06z with passage of the
cold front.
Concern also remains for precipitation chances on Tuesday. There is
better agreement in the 00z runs pointing to active convection
working across SW MO during the morning. While the POP/QPF bullseye
with this activity should be well southwest of our CWA, primary
question is if and/or how much of this activity will be able to work
into our CWA as it shears off to the southeast with the slowly
increasing NW mid level flow. For now I have held onto slight
chance POPs as far north as a COU-SAR line for the morning hours;
this still may be too far north but will wait for today`s model runs
to confirm this above thinking before making additional cuts to
POPs.
For the remainder of the week, medium range solutions are still
indicating that a series of shortwaves rotating around upper low
over southeast Canada will lower heights over the eastern CONUS.
This shift in the UA pattern will allow Canadian high pressure to
build into, and then become locked over, the mid-Mississippi Valley.
The net result should be several days of dry and relatively cool
August weather. There has been little run-to-run change in the
progged temperature profile across the region during this time, so
it still looks like temperatures in the Wednesday-Friday time frame
will be averaging 5-10 degrees below normal. Progged 850mb temps as
well as MOS guidance suggests highs in the 75-80 degree range, with
lows primarily in the 50s.
00z GFS and ECMWF are still hinting at a secondary shortwave
dropping into the mid-Mississippi valley and developing a cut-off
low in the vicinity of the lower Ohio valley heading into the
weekend. This certainly bears watching, but latest guidance
suggests that primary moisture surge, and precipitation threat, will
be ahead of this feature, and primarily east of our CWA. So for
now have maintained a dry forecast for the weekend, with gradual
modification of the airmass allowing for a slow warming trend.
Truett
&&
.AVIATION: (For the 12z TAFs through 12z Tuesday Morning)
Issued at 549 AM CDT Mon Aug 12 2013
Showers and thunderstorms are expected to develop across MO/IL
today ahead of an approaching cold front. Winds will turn westerly
to northwesterly behind the front, then continue veering
overnight. Periods of MVFR/IFR conditions will be possible when
showers/thunderstorms move directly over the terminals.
Specifics for KSTL: KSTL was on the northern edge of a warm front
early this morning. Once the warm front lifts northward, winds
will switch from southeasterly to southerly. Showers and
thunderstorms are expected to develop near KSTL this afternoon
ahead of an approaching cold front. Winds will turn northwesterly
behind the front, then continue veering overnight and become
northeasterly tomorrow morning. Periods of MVFR/IFR conditions
will be possible when showers/thunderstorms move directly over the
terminal.
Kanofsky
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
649 AM CDT Mon Aug 12 2013
...Flash Flood Watch Now In Effect for the Entire Forecast Area...
.MESOSCALE DISCUSSION...
Issued AT 645 AM CDT MON AUG 12 2013
A large area of convection continues to spread across eastern
Kansas toward western Missouri this morning. A veered low level
jet will support this activity spreading east into southern
Missouri this morning. Precipitable water values near 1.75 inches
and 850 mb dewpoints near 15 degrees Celsius will support
efficient rainfall production. RAP model analysis suggest a layer
of dry air in the mid levels but expect this to be overcome by
advection of deeper moisture into the area. With the approach of
this expansive area of rain the Flash Flood Watch has been
expanded to cover the entire forecast area beginning this morning.
Some areas of central and eastern Missouri may be dropped later
today if precipitation and model trends dictate.
Most unstable CAPE of 1000 to 2000 J/KG will support thunderstorms
and a few stronger updrafts. Severe weather is not expected this
morning but winds to 40 mph will be possible in the stronger
convection.
&&
.SHORT TERM...(Today through Wednesday) ISSUED AT 322 AM
CDT MON AUG 12 2013
Large scale upper level flow pattern shows very little change
through early this work week as a broad upper level vortex over
eastern Canada remains pretty much stationary...only starting to
lift out to the North Atlantic on Wednesday. Meanwhile...the
upper ridge over the Southwestern United States extending from Texas
northwestward toward Alberta remains essentially stationary.
This pattern will continue to produce the persistent northwest
upper level flow we have have seen for quite some time now over
Missouri and over much of the continent to our north and east. Two
weak but progressive short wave trofs embedded in this flow will
dive southeastward from the Northern High Plains into the area or
just to our southwest over Oklahoma Today and again later
Tuesday.
At the Surface and Lower levels Models are in now far better
agreement thorough Wednesday. All seem to focus most surface to
850 mb forcing over far Southwestern Missouri and just over NE
Okla/NW Ark with lower level Gulf moisture flux best to our
southwest also. Given this synoptic setup...expect the highest total
QPF values...around two inches to be over far southwestern Missouri
and extreme southeastern Kansas. Potential flash flooding will
therefore be a concern in this area and expect to issue a Flash
Flood Watch early this morning.
Through today and Tuesday...the potential for severe weather is not
high...but some stronger to marginally severe storms may be possible
as best surface based and MU cape values are also over far
southwestern Missouri. Zero to six KM bulk shear is running around
30 kts. The primary severe threat would be from winds.
Expect gradual clearing overnight Tuesday and early on Wednesday as
Canadian High Pressure and its associated Cold Front move southward
into the area.
.LONG TERM...(Thursday THROUGH Sunday) ISSUED AT 322 AM
CDT MON AUG 12 2013
The upper level vortex over Eastern Canada continues to slide
eastward into the North Atlantic and its associated upper trof
shifts southeastward toward the Appalachian ridge while weakening.
Upper ridging over the Rockies amplifies somewhat through the period
while sliding eastward into the High Plains.
After a Cold Front pushes south of the area Tuesday
night...Wednesday through Saturday will bring much drier and very
comfortable conditions as a seasonably strong surface Canadian high
pressure system behind this front sinks well south of the area.
Expect daytime highs to be in the upper 70s to lower 80s with
overnight lows in the lower upper 50s to lower 60s during this
time frame.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
ISSUED AT 645 AM CDT MON AUG 12 2013
Pilots can expect deteriorating flight conditions today as showers
and thunderstorms spread across the area.
Areas of MVFR to localized IFR conditions can be expected in areas
of morning fog and the heavier precipitation.
Precipitation may temporarily taper off later today but areas of fog
and lower ceilings will develop tonight.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...FLASH FLOOD WATCH through Tuesday evening FOR MOZ055>058-066>071-
077>083-088>098-101>106.
KS...FLASH FLOOD WATCH through Tuesday evening FOR KSZ073-097-101.
&&
$$
MESOSCALE...Foster
SHORT TERM...Colucci
LONG TERM...Colucci
AVIATION...Foster
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
254 PM MDT Mon Aug 12 2013
.DISCUSSION...
Tonight through Wednesday...Overall pattern has changed little
from Sunday. The airmass is a bit more unstable this afternoon
with CAPE values of 1000 to 2000 J/kg across the northern portion
of the county warning area. Shear values, though not overly
impressive, have also increased from earlier this morning and with
high precipitable water, the result is thunderstorm development.
The weak steering flow aloft will make very slow movers with these
storms and heavy rain will be the primary threat (although some
hail cannot be ruled out). HRRR and RUC analysis continue to
develop thunderstorms over Great Falls as late as 04 to 05z. Drier
conditions over southwest Montana will translate to isolated
thunderstorms this evening. Enough instability will exist Tuesday
afternoon to allow isolated to scattered thunderstorms to develop
again though areal coverage should be less. Rising H5 heights
Wednesday will herald the beginning of a drier and warmer regime.
Temperatures will be near or slightly above seasonal averages.
Emanuel
Wednesday Night through Monday...Medium range forecast remains
relatively unchanged tonight. Models are in good agreement from
mid-week until early in the weekend and indicate that an upper level
ridge will be over the Rocky Mountains for a very warm and generally
dry forecast period. Model consensus for the weekend through early
next week remains elusive. Models agree that the ridge will be
pushed eastward on Saturday as a broad upper level trough moves
inland along the west coast. Beyond Saturday, models set up a
roughly zonal flow aloft but bring multiple and frequent short waves
over the region. Unfortunately, the wave phase and speed differ
markedly between the models and significant disagreement with regard
to pops/clouds/weather timing arises. Am sticking with a solution
that trends temperatures slightly cooler and increases pops toward
climatology for the weekend through Monday. mpj
&&
.AVIATION...
UPDATED 1740Z.
Expect generally VFR conditions. Scattered showers/thunderstorms are
expected to develop over southwest Montana by mid-afternoon then
spread northeast later in the afternoon and evening. A few
thunderstorms could also develop over the plains by mid-afternoon.
There will be a threat of brief MVFR/IFR conditions in heavy rain
along with small hail with the thunderstorms except those over far
southwest Montana. Showers/thunderstorms are expected to diminish
over southwest Montana by dark and finally over the area from KHVR
to KLWT after midnight. Although not mentioned in the tafs there is
a small risk for patchy MVFR/IFR ceilings/visibilities in fog over
the plains late tonight and early Tuesday morning should skies clear
after the showers/thunderstorms. However some guidance does not
clear skies which would prevent fog formation. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 55 84 55 86 / 40 30 30 20
CTB 52 82 52 85 / 40 30 20 10
HLN 57 86 57 89 / 30 30 40 20
BZN 50 85 49 86 / 30 30 30 20
WEY 39 78 37 78 / 10 20 20 10
DLN 49 83 49 84 / 20 20 20 20
HVR 57 82 56 84 / 40 20 30 20
LWT 54 81 53 81 / 40 40 30 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING until 8 PM MDT this evening Beaverhead...
Jefferson...Madison.
&&
$$
weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
414 PM CDT MON AUG 12 2013
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 414 PM CDT MON AUG 12 2013
THE MAIN ISSUES DURING THE NEXT 24 HOURS INCLUDE FICKLE
THUNDERSTORM CHANCES...ALONG WITH WHETHER OR NOT FOG TONIGHT MIGHT
END UP BEING IMPACTFUL IN SOME SPOTS.
20Z OBJECTIVE SURFACE ANALYSIS SHOWS A WEAK COLD FRONT STRETCHED
ACROSS KS FROM SOUTHWEST-NORTHEAST...WHILE TO THE NORTH OF THIS
BOUNDARY...THE MAJORITY OF THE CWA IS EXPERIENCING LIGHT BREEZES
RANGING FROM NEAR-CALM TO NO MORE THAN 5-10 MPH FROM THE EAST-
NORTHEAST UNDER THE INFLUENCE OF BROAD HIGH PRESSURE EXTENDING
WELL SOUTHWARD FROM CANADA. ALOFT...WATER VAPOR IMAGERY AND SHORT
TERM MODEL DATA SHOWS GENERALLY WEST-NORTHWEST FLOW ALOFT OVER THE
CENTRAL PLAINS...MORE WESTERLY UP AROUND 300 MILLIBARS..AND MORE
NORTHERLY FARTHER DOWN IN THE MID LEVELS 500/700 MILLIBARS. THIS
FLOW REGIME REMAINS ESTABLISHED BETWEEN A LARGE SCALE TROUGH OVER
THE GREAT LAKES/SOUTHEAST CANADA AREA...AND A RIDGE EXTENDING
NORTH-NORTHWEST INTO THE ROCKIES OUT OF THE TX/NORTHERN MEXICO
AREA. IN TERMS OF THE REGIONAL SCALE...THE MAIN LOW AMPLITUDE
DISTURBANCE OF INTEREST HAS PASSED ONTO THE EAST INTO
MO...ALTHOUGH SMALL RIBBONS OF CHANNELED VORTICITY ARE EVIDENT
EXTENDING BACK WEST-NORTHWEST ACROSS THE SOUTHERN CWA TOWARD THE
WY/NE/CO BORDER AREA PER LATEST OBJECTIVE MESO-ANALYSIS.
DESPITE WHAT VARIOUS MODELS WERE EARLIER-SHOWING...THE CWA HAS
REMAINED DRY ALL DAY IN THE WAKE OF THE EXTENSIVE CONVECTION
SUNDAY EVENING/EARLY THIS MORNING. VISIBLE SATELLITE REVEALS ONLY
A SCATTERED TO LOCALLY BROKEN FAIR WEATHER CUMULUS FIELD MAINLY IN
THE FAR NORTHERN/EASTERN/SOUTHERN COUNTIES...AND HIGH TEMPERATURES
ARE ON TRACK TO TOP OUT 82-85 NEARLY ALL AREAS.
FOR LATE THIS AFTERNOON INTO THIS EVENING...MODELS CONTINUE TO
STRUGGLE WITH THEIR INDIVIDUAL QPF FIELDS...AS SOME APPEAR TO
THINK THAT CONVECTION WILL BREACH A WEAK CAP LOCALLY. LEANING
TOWARD THE HIGHER-RES SOLUTIONS OF THE HRRR AND 4KM WRF
NMM/ARW...IT APPEARS RATHER UNLIKELY THAT ANYTHING WILL POP IN THE
NEXT 3-6 HOURS ESPECIALLY ACROSS THE CENTRAL/EASTERN CWA DUE TO
LACK OF FORCING AND LACK OF LOW-LEVEL CONVERGENCE...AS THE WEAK
CAP SHOULD HOLD DESPITE THE PRESENCE OF 1000-1500 J/KG 0-1KM MIXED
LAYER CAPE PER LATEST RUC ANALYSIS. AS A RESULT...THROUGH MIDNIGHT
HAVE CONFINED SLIGHT POPS TO MAINLY THE WESTERN 1/4 TO 1/3 OF THE
CWA...MAINLY TO ACCOUNT FOR THE SMALL POSSIBILITY THAT STORMS
CURRENTLY DEVELOPING IN WESTERN NEB...AND MAYBE EVENTUALLY IN
NORTHWEST KS AS WELL...MIGHT SLIP EASTWARD INTO THE CWA. GIVEN THE
CONTINUED WEAK DEEP LAYER SHEAR REGIME ONLY AROUND 20KT...AND
INSTABILITY FADING WITH TIME TONIGHT...THINK THE PROBABILITY OF
STRONG THUNDERSTORMS...LET ALONE SEVERE...IS QUITE LOW. AFTER
MIDNIGHT...UNCERTAINTY CONTINUES TO GROW...BUT WITH BOTH THE
LATEST HRRR AND 18Z NAM ADVERTISING SOME CONVECTION FLARING UP
MAINLY JUST NORTHWEST OF THE CWA LIKELY IN RESPONSE TO SOME SUBTLE
MID LEVEL THETA-E ADVECTION...AND OTHER MODELS SHOWING CONVECTION
LURKING IN OR NEAR KS ZONES...WENT AHEAD AND EXPANDED 20-30 POPS
TO INCLUDE ALL BUT A HANDFUL OF SOUTHEASTERN COUNTIES JUST IN
CASE. THE OTHER POTENTIAL ISSUE TONIGHT IS FOG. WHILE MET/MAV
GUIDANCE IS SUGGESTING ONLY SOME LIGHT FOG...THE 15Z SREF SUGGESTS
PERHAPS AN ENHANCED RISK OF VISIBILITY RESTRICTIONS BELOW 1 MILE
ESPECIALLY ACROSS THE SOUTHWEST 1/3 OF THE CWA LATE TONIGHT.
CERTAINLY THE VERY LIGHT EASTERLY FLOW REGIME AND RECENT RAINFALL
COULD HELP THE CAUSE OF FOG FORMATION...BUT GIVEN THAT FOG DID NOT
BECOME TOO MUCH OF AN ISSUE LAST NIGHT IN THE WAKE OF DEPARTING
CONVECTION WITH A SIMILAR WIND REGIME...DECIDED TO ONLY INTRODUCE
A PATCHY FOG MENTION CWA-WIDE FOR NOW LATE TONIGHT...AND DEFER TO
NEXT FEW SHIFTS TO MONITOR THE SITUATION AND RAMP UP FOG POTENTIAL
IF NECESSARY.
TURNING TO THE TUESDAY DAYTIME HOURS...THE QUESTIONS JUST CONTINUE
TO ARISE. TAKING VARIOUS MODEL QPF FIELDS AT FACE VALUE...THERE
COULD BE QUITE A BIT OF ONGOING CONVECTION DURING THE
DAY...ESPECIALLY ACROSS THE WESTERN HALF OF THE CWA...POSSIBLY AS
A CONTINUATION OF OVERNIGHT ACTIVITY MOVING IN...OR LOCAL
DEVELOPMENT RAMPING UP WITH DAYTIME HEATING...AS THE THERMODYNAMIC
STRUCTURE OF THE ATMOSPHERE SHOULD REMAIN SIMILAR TO TODAY WITH
WEAK CAPPING IN THE PRESENCE OF ROUGHLY 1000 J/KG OF CAPE. THE
MILLION DOLLAR QUESTION IS WHETHER NOT FORCING WILL BE STRONG
ENOUGH TO REALIZE THE POTENTIALLY WIDESPREAD CONVECTION ADVERTISED
BY SOME MODELS...OR WHETHER MODELS ARE OVER-DOING QPF AS SEVERAL
DID FOR TODAY. THERE SHOULD AT LEAST BE A FEW SUBTLE SHORTWAVE
TROUGHS PASSING THROUGH THE REGION PER MODEL VORTICITY
FIELDS...PRIMARILY PASSING ACROSS THE SOUTHWEST 1/2 OF THE CWA AND
POINT SOUTH. FOR NOW...DECIDED TO MAKE LITTLE CHANGE TO PREVIOUS
FORECAST WHICH ALREADY HAD POPS LOW AT NO MORE THAN 20-30
PERCENT...WITH THESE CHANCES COVERING MOST OF THE CWA IN THE
MORNING...AND THE ENTIRE AREA IN THE AFTERNOON. IF FORCING IS IN
FACT ENOUGH TO GENERATE WIDESPREAD CONVECTION...THEN NEXT SHIFT
MAY HAVE TO RAISE POPS NOTICEABLY ESPECIALLY IN WESTERN
AREAS...BUT AFTER SEEING HOW TODAY ENDED UP BONE-DRY THROUGH LATE
AFTERNOON...THINK IT WOULD BE UNWISE TO GET CARRIED AWAY WITH RAIN
CHANCES EVEN 12-24 HOURS OUT. AGAIN...NOT EXPECTING ANY SEVERE
STORMS...BUT A LOCALIZED STRONG STORM PROBABLY NOT OUT OF THE
QUESTION. OBVIOUSLY HIGH TEMPERATURES WILL BE HIGHLY DEPENDENT ON
THE COVERAGE...OR LACK THEREOF...OF DAYTIME CONVECTION...SO THERE
IS SOME UNCERTAINTY HERE TOO. GIVEN A SIMILAR LOW-LEVEL TEMP
REGIME...BLENDED THE COOLER PREVIOUS FORECAST FOR TOMORROW WITH
READINGS SIMILAR TO THOSE OBSERVED TODAY...WHICH RESULTS IN A
SLIGHT INCREASE TO PREVIOUS HIGHS AND NOW CALLING FOR 79-82 MOST
AREAS. BREEZES DURING THE DAY SHOULD AVERAGE ONLY 5-10 MPH FROM
THE EAST ASSUMING CONVECTIVE OUTFLOW DOESN/T GET TOO INVOLVED.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 414 PM CDT MON AUG 12 2013
HE COOLER THAN NORMAL TREND WILL LIKELY CONTINUE THROUGH AT LEAST
SATURDAY...WITH PERHAPS A RETURN OF NEAR NORMAL HIGHS BY SUNDAY AND
MONDAY. WEAK SHORT WAVES WILL TRACK ACROSS OUR FORECAST AREA WITHIN
THE PERSISTENT UPPER LEVEL NORTHWESTERLY FLOW REGIME.
CONSEQUENTLY...ISOLATED TO SCATTERED THUNDERSTORMS WILL REMAIN
POSSIBLE ACROSS AT LEAST PORTIONS OF OUR FORECAST AREA OFF AND ON
AGAIN THROUGH MUCH OF THE PERIOD.
TUESDAY NIGHT THROUGH WEDNESDAY...A DECENT 500 MB VORT MAX/SHORT
WAVE WILL TRACK SOUTHEAST ACROSS THE HIGH PLAINS BRINGING A CHANCE
OF THUNDERSTORMS PRIMARILY TO AREAS WEST OF OUR FORECAST AREA.
HOWEVER...THERE IS GENERALLY A SLIGHT CHANCE THAT A FEW OF THESE
THUNDERSTORMS COULD TRACK INTO OUR WESTERN ZONES PRIMARILY WEST OF
HWY 281. INSTABILITY AND SHEAR ARE BOTH WEAK AND THUS ANY
THUNDERSTORMS THAT WORK INTO OUR AREA WILL LIKELY BE NON SEVERE.
TEMPERATURES WILL BE COOL FOR THIS TIME OF YEAR WITH THE UPPER LEVEL
JET STREAM TO OUR SOUTH.
WEDNESDAY NIGHT THROUGH FRIDAY...THIS SHOULD BE OUR BEST CHANCE AT
MORE WIDESPREAD THUNDERSTORM POTENTIAL ACROSS THE FORECAST AREA AS
A TRAIN OF SUCCESSIVE SHORT WAVE TROUGHS WORK THEIR WAY ACROSS THE
CENTRAL PLAINS. UPPER LEVEL SHEAR AND INSTABILITY WILL ALSO BE ON
THE INCREASE ESPECIALLY THURSDAY AFTERNOON THROUGH FRIDAY...WHICH
MAY RESULT IN A FEW STRONG TO POTENTIALLY SEVERE THUNDERSTORMS. AT
THIS POINT...IT DOES NOT APPEAR TO BE A WIDESPREAD SEVERE
EVENT...BUT CAN NOT RULE OUT THE POSSIBILITY OF ISOLATED SEVERE
STORMS. TEMPERATURES WILL REMAIN RELATIVELY COOL...UPPER 70S TO
AROUND 80 DUE TO CLOUDS...POTENTIAL PRECIPITATION...AND MEAN MID
AND UPPER LEVEL JET POSITION.
SATURDAY AND SUNDAY...A BIT OF AN UPPER RIDGE IS PREDICTED TO WORK
INTO OUR FORECAST AREA THAT IF IT VERIFIES WOULD RESULT IN DRY
CONDITIONS THIS WEEKEND AND THEN WARMING TEMPERATURES TO NEAR NORMAL
BY SUNDAY.
SUNDAY NIGHT AND MONDAY...THE NEXT UPPER SHORT WAVE IS PROJECTED BY
BOTH THE 12Z GFS AND 12Z ECMWF TO MOVE INTO THE CENTRAL PLAINS. THIS
WILL RESULT IN AT LEAST SOME CHANCE OF THUNDERSTORMS...PARTICULARLY
ACROSS OUR WEST...ALTHOUGH THESE CHANCES MAY EVENTUALLY NEED TO BE
EXPANDED/RAISED SHOULD CURRENT FAVORABLE MODEL TRENDS CONTINUE.
ALLBLEND GIVES US NEAR NORMAL TEMPERATURES...AND LIKELIHOOD IS THAT
WE WILL LIKELY BE NO WARMER THAN NORMAL...AND WOULD NOT BE SURPRISED
IF MONDAY HIGHS GET LOWERED SOME WITH FUTURE FORECAST UPDATES.
&&
.AVIATION...(FOR THE 18Z KGRI TAF THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1252 PM CDT MON AUG 12 2013
AT THIS TIME...THE ONLY NON-VFR TIME FRAME IN THE FORECAST IS A
PERIOD OF MVFR VISIBILITY THAT HAS BEEN INTRODUCED FROM 08Z-13Z
TONIGHT/EARLY TUESDAY MORNING TO COVER THE POSSIBILITY OF FOG
DEVELOPMENT GIVEN THE COMBINATION OF LIGHT EASTERLY FLOW AND
MOISTURE FROM RECENT RAINFALL. CONFIDENCE IS CERTAINLY QUITE LOW
ON THE LIKELIHOOD/MAGNITUDE OF FOG DEVELOPMENT...AND COULD
POTENTIALLY SEE IT BEING WORSE THAN CURRENTLY
ADVERTISED...ALTHOUGH AVAILABLE MODELS/GUIDANCE SUGGEST THAT MVFR
VISIBILITY IS A GOOD FORECAST COMPROMISE FOR NOW. OTHERWISE...THE
MAJORITY OF THE PERIOD HAS HIGH CONFIDENCE OF VFR CONDITIONS...WITH
ONLY THE SLIGHTEST CHANCE OF A SHOWER/THUNDERSTORM LATE THIS
AFTERNOON ONWARD...BUT THIS RISK APPEARS TOO LOW TO EVEN SUPPORT A
VICINITY THUNDERSTORM MENTION. SURFACE BREEZES WILL GENERALLY
PREVAIL FROM AN EASTERLY DIRECTION...WITH SUSTAINED SPEEDS
UNLIKELY TO EXCEED 7KT THROUGHOUT.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...WESELY
AVIATION...PFANNKUCH
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
330 PM CDT MON AUG 12 2013
.SYNOPSIS...
ISSUED AT 330 PM CDT MON AUG 12 2013
THE 12Z H5 ANALYSIS FROM EARLIER THIS MORNING HAD A HIGH
AMPLITUDE RIDGE EXTENDING FROM THE NRN ROCKIES INTO THE YUKON AND
WESTERN PORTIONS OF THE NW TERRITORIES OF CANADA. FURTHER EAST...A
TROUGH OF LOW PRESSURE EXTENDED FROM CENTRAL QUEBEC SWD INTO THE
EASTERN GREAT LAKES. A STRONG SHORTWAVE WAS NOTED OVER WRN ONTARIO
WITH DECENT HT FALLS NOTED OVER CENTRAL AND EASTERN ONTARIO. HIGH
PRESSURE EXTENDED ALONG THE GULF COAST...WEST TO NRN MEXICO. SEVERAL
EMBEDDED SHORTWAVES WERE NOTED ACROSS THE INTERMOUNTAIN WEST...MOST
NOTABLY IN CENTRAL AZ AND NRN UT. CLOSER TO WESTERN AND NORTH
CENTRAL NEBRASKA...MORNING STRATUS HAS BURNED OFF...BUT WITH A WEAK
CAP IN PLACE...ABUNDANT CU HAS DEVELOPED OVER THE PAST
HOUR...ESPECIALLY ALONG THE HIGHWAY 61 CORRIDOR FROM HYANNIS TO
IMPERIAL...INVOF OF WESTWARD MOVING SURFACE BOUNDARY. TEMPERATURES
AS OF 2 PM CDT...WERE IN THE UPPER 70S AND LOWER 80S.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 330 PM CDT MON AUG 12 2013
THE MAIN FORECASTING CHALLENGE OVER THE NEXT 24 HOURS
IS PRECIPITATION CHANCES. THE NEAR TERM MODELS THIS MORNING...MOST
NOTABLY THE GFS AND NAM SOLNS DIDN`T INITIALIZE WELL WITH A MCV
NOTED OVER CENTRAL NEBRASKA. THIS FEATURE WAS WAY OVERDONE THIS
MORNING...AND LENDS A LOT OF DOUBT AS TO HOW THESE MODELS WILL
HANDLE ANY CONVECTION THIS EVENING. THE 09Z SREF...INITIALIZED
BETTER AND WAS NOT OVERLADEN WITH QPF LIKE THE GFS AND NAM SOLNS
WERE. WITH THIS IN MIND...POPS WERE TRIMMED BACK IN THE EASTERN
ZONES FOR TONIGHT...AS THE BULK OF ANY PCPN WILL BE FOCUSED INVOF
OF THE SURFACE BOUNDARY ACROSS THE WESTERN CWA. DEEP LAYER SHEAR
REMAINS WEAK OVER THE WESTERN HALF OF THE FORECAST AREA...SO ANY
THREAT FOR SEVERE STORMS IS VERY MINIMAL ATTM. OVERNIGHT
TONIGHT...THE MODELS ARE INDICATING THE DEVELOPMENT OF A WEAK LOW
LEVEL JET ACROSS THE PANHANDLE AND WESTERN CWA...SO THE THREAT FOR
STORMS...SHOULD BE MINIMAL IN THE EASTERN CWA. BETTER CHANCES FOR
PCPN ARRIVE EARLY TUESDAY MORNING AS A DECENT SHORT WAVE LIFTS
FROM THE CENTRAL ROCKIES EWD INTO KS AND NEBRASKA. SREF
PROBABILITIES FOR MEASURABLE PCPN APPROACH 90 PERCENT IN THE
CENTRAL AND SOUTHWESTERN FORECAST AREA BY TUESDAY AND RAISED POPS
WEST OF HIGHWAY 83. LIKE TODAY...THE THREAT FOR SEVERE STORMS WILL
BE SMALL GIVEN THE VERY WEAK CAPPED ENVIRONMENT AND WEAK DEEP
LAYER SHEAR. SKIES TOMORROW WILL BE PARTLY TO MOSTLY
CLOUDY...WHICH WILL KEEP HIGHS IN THE 70S. LOWS TONIGHT WILL BE IN
THE UPPER 50S TO AROUND 60 UNDER PARTLY TO MOSTLY CLOUDY SKIES.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 330 PM CDT MON AUG 12 2013
THIS PERIOD WILL START OFF WITH AN UPPER LEVEL OVER THE
INTERMOUNTAIN WEST AND AN UPPER TROUGH PASSING THROUGH THE GREAT
LAKES REGION. THIS WILL LEAVE NEBRASKA UNDER NORTHWEST FLOW ALOFT
AND SURFACE HIGH PRESSURE OVER THE WESTERN GREAT LAKES. THE SURFACE
HIGH WILL SLOWLY DRIFT SOUTHEAST INTO THE OHIO RIVER VALLEY THROUGH
THE REST OF THE WEEK...WHILE THE UPPER RIDGE AXIS IN THE WEST SLOWLY
APPROACHES THE HIGH PLAINS.
A FEW THUNDERSTORMS MAY BE UNDERWAY ACROSS CENTRAL AND WESTERN
NEBRASKA COME TUESDAY EVENING. THE BEST CHANCE LOOKS TO BE IN THE
WESTERN FORECAST AREA DURING THE EVENING...BUT THEN SHIFTS TO THE
NORTHEAST LATE IN THE NIGHT. DEEP SHEAR LOOKS RATHER LIMITED TUESDAY
NIGHT...SO SEVERE CHANCES LOOK SLIM. AN UPPER LEVEL WAVE WILL MOVE
THROUGH THE AREA WEDNESDAY NIGHT...WITH THUNDERSTORM ACTIVITY
STARTING IN THE WEST AND SHIFTING EAST OVERNIGHT. GFS HAS BETTER
SHEAR ON WED AFTERNOON/EVENING...HOWEVER BELIEVE ITS OVERDONE A BIT
BASED ON INPUT FROM THE NAM AND SREF MODELS. STILL...BELIEVE
WEDNESDAY NIGHT HAS THE BEST CHANCE FOR PRECIPITATION ACROSS THE
AREA DURING THIS PERIOD. MODELS INDICATE ANOTHER WAVE MAY MOVE
THROUGH THE REGION ON THURSDAY...BUT WITH MOST OF THE ACTIVITY IN
THE EAST.
THE UPPER RIDGE AXIS SHIFTS INTO THE HIGH PLAINS OVER THE
WEEKEND...ALLOWING TEMPS TO INCREASE SOMEWHAT...WITH HIGHS IN THE
MID 80S TO NEAR 90. AFTER A BREAK FROM THUNDERSTORM ACTIVITY FR DAY
NIGHT THROUGH SUNDAY...MODELS INDICATE THERE MAY BE ANOTHER
DISTURBANCE MOVING THROUGH THE REGION BY SUNDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1228 PM CDT MON AUG 12 2013
A TRICKY AVIATION FORECAST IS IN THE CARDS OVER THE NEXT 24 HOURS
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. WEAK MID LEVEL FLOW AND
THE LACK OF A FRONTAL BOUNDARY WILL MAKE IT DIFFICULT TO PINPOINT
TIMING AND LOCATION OF THUNDERSTORMS TONIGHT. BOTH THE NAM AND GFS
SOLNS HAD SOME SIGNIFICANT INITIALIZATION ISSUES THIS MORNING AND
RELIED HEAVILY ON THE SREF AND HIRES RUC SOLNS FOR THE 18Z TAF
FCSTS. THAT BEING SAID...THINKING HERE IS THAT MID AND UPPER LEVEL
CLOUDINESS WILL BE ON THE INCREASE LATER THIS AFTERNOON AND THIS
EVENING AS CONVECTION DIES OFF TO THE WEST OF THE FORECAST AREA.
COVERAGE OF ANY ISOLATED TSRAS THIS EVENING WILL BE TOO SPARSE TO
INCLUDE IN THE 18Z TAFS. HOWEVER...HIGHER CONFIDENCE IN
THUNDERSTORMS CREEPS INTO THE FORECAST ON TUESDAY MORNING AS THE
SREF...GFS AND NAM SOLNS BEGIN TO COME INTO BETTER AGREEMENT WITH
TSRA CHANCES ACROSS WESTERN NEBRASKA. WILL HANDLE THIS THREAT FOR
TSRAS WITH A PROB 30 GROUP AT BOTH TERMINALS FOR TUESDAY MORNING.
CIGS OVER THE NEXT 24 HOURS WILL GENERALLY RANGE FROM 6000 TO 15000
FT AGL. THE EXCEPTION WILL BE AT THE KVTN TERMINAL...AS SOME 1500 TO
2500 FT AGL CIGS ARE POSSIBLE AT THE KVTN TERMINAL THROUGH MID
AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CLB
SHORT TERM...CLB
LONG TERM...KNUTSVIG
AVIATION...CLB
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1228 PM CDT MON AUG 12 2013
.SYNOPSIS...
ISSUED AT 302 AM CDT MON AUG 12 2013
THUNDERSTORM ACTIVITY ASSOCIATED WITH DEEP MOISTURE AND A BELT OF
STRONG WESTERLIES AT 300 MB SHOULD CONTINUE THROUGH WEDNESDAY
NIGHT. THEREAFTER...WINDS ALOFT BECOME NORTH PRODUCING SUBSIDENCE.
RAIN CHANCES WILL DIMINISH AS THE ATMOSPHERE DRIES OUT.
&&
.UPDATE...
ISSUED AT 1038 AM CDT MON AUG 12 2013
JUST UPDATED THE ONGOING FORECAST TO TAKE OUT MENTION OF
FOG...LOWER MAX TEMPS SLIGHTLY BASED ON TEMPERATURE TRENDS...AND
TRIMMED POPS FROM THE FORECAST IN THE EAST THIS AFTERNOON. A
FAIRLY IMPRESSIVE AREA OF FOG DEVELOPED OVER PORTIONS OF NORTH
CENTRAL...CENTRAL AND SOUTHWESTERN NEBRASKA EARLIER THIS MORNING.
SOME VISBYS DOWN TO A QUARTER MILE OR LESS WERE NOTED...ESPECIALLY
IN RIVER VALLEYS AND LOW LYING AREAS. IN PARTICULAR, THE HIGHWAY
20 CORRIDOR FROM VALENTINE TO ONEILL AND ALONG THE INTERSTATE 80
AND HIGHWAY 26 CORRIDORS FROM CHAPPELL TO OGALLALA TO NORTH
PLATTE...AND FROM LISCO TO OGALLALA. THIS FOG IS EXPECTED TO
TOTALLY BURN OFF BY 11 AM CDT (10 AM MDT). FORECAST HIGHS WERE
MODIFIED DOWNWARD SLIGHTLY FOR TODAY IN THE EAST AS MOSTLY CLOUDY
SKIES WILL CONTINUE THROUGH LATE MORNING. FINAL CHANGES WERE MADE
TO PRECIPITATION CHANCES FOR THIS AFTERNOON. ATTM HAVE LITTLE
CONFIDENCE IN THE NAM SOLUTION AS IT INITIATED AN AREA OF
THUNDERSTORMS ACROSS THE CENTRAL AND WESTERN CWA THIS MORNING.
RELIED MORE ON THE HI RES RUC...WHICH DEVELOPS ISOLATED TSRAS IN
THE CENTRAL AND WEST LATER THIS AFTERNOON. WITH NO CAP NOTED IN
THE FORECAST AREA THIS SOLN SEEMS PLAUSIBLE LATER THIS AFTERNOON.
UPDATE ISSUED AT 702 AM CDT MON AUG 12 2013
AREAS OF FOG SOME DENSE CONTINUED TO DEVELOP OVER WESTERN NEBRASKA
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 302 AM CDT MON AUG 12 2013
MODELS IN FAIR AGREEMENT AND HAVE USED A BLEND FOR THE FORECAST. NAM
SOLUTIONS FOR SUNDAY WERE MUCH BETTER THAN GFS FORECAST SO WILL
TREND FORECAST TOWARDS NAM SOLUTIONS. FRONT CAME THROUGH WITH MUCH
COOLER AIR YESTERDAY ONLY MADE IT INTO THE 70S OVER NORTH CENTRAL
NEBRASKA. CLOUDS CLEARING OUT QUICKLY THIS MORNING. WILL SEE SOME
REBOUND IN TEMPERATURES WITH MOST AREAS SEEING 80S TODAY.
INSTABILITY THIS AFTERNOON AND A MID LEVEL WAVE MOVING SOUTH ACROSS
THE NORTHERN PLAINS WILL PROVIDE ENOUGH FORCING FOR THUNDERSTORM
DEVELOPMENT ACROSS THE NEBRASKA SANDHILLS MID TO LATE AFTERNOON.
THUNDERSTORMS ALSO EXPECTED TO DEVELOP ALONG STATIONARY BOUNDARY
ACROSS THE NEBRASKA PANHANDLE LATE AFTERNOON AND TO PUSH EAST OVER
NIGHT. TEMPERATURES FALLING INTO 50S FOR OVER NIGHT LOWS.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 302 AM CDT MON AUG 12 2013
TUESDAY THROUGH WEDNESDAY NIGHT...
PERSISTENT SOUTH WINDS AND LOW LEVEL MOISTURE FEED SHOULD CONTINUE
THROUGH THURSDAY WITH THE ATMOSPHERE DESTABILIZING EACH AFTERNOON
AND EVENING. THERE ARE OPPORTUNITIES FOR NOCTURNAL MCS DEVELOPMENT
ALSO BUT THE MODELS DONT GIVE A CONSISTENT SIGNAL AS TO WHICH NIGHT
OR NIGHTS THIS WILL OCCUR. THE GEMREG FIRES A NOCTURNAL MCS ACROSS
THE NERN ZONES LATE TONIGHT WHILE THE NAM AND ECM FAVOR THE SAME
LOCATION LATE TUESDAY NIGHT. THE GFS DEVELOPS CONVECTION WEDNESDAY
NIGHT BUT THE NAM AND ECM ARE QUIET. OVERALL THE MODELS FAVOR WRN
AND NCNTL NEB FOR HIGHEST QPF VERSUS THE HIGH PLAINS TO THE WEST AND
THE MISSOURI VALLEY TO THE EAST.
DEEP UPPER LEVEL MOISTURE WILL CONTINUE TO FEED CLOCKWISE AROUND THE
UPPER LEVEL RIDGE ACROSS THE CNTL ROCKIES. THIS IN COMBINATION WITH
A BELT OF MODERATE WESTERLIES AROUND 50 KT AT 300MB ASSURES SUPPORT
FOR STORM DEVELOPMENT. GIVEN THAT THE 500MB FLOW WILL REMAIN WEAK AT
JUST 10 TO 20 KT...STORMS SHOULD CONTINUE TO EXHIBIT WEAK
ROTATION...TEND TO BE OUTFLOW DOMINANT AND COLD POOL DRIVEN. THUS
THE SEVERE WEATHER THREAT WILL BE RELATIVELY LOW UNLESS A SITUATION
DEVELOPS WHERE THE COLD POOL BECOMES VERY UNSTABLE AND DISCRETE
STORM DEVELOPMENT PRODUCES BOW SEGMENTS WHICH WOULD INCREASE THE RISK
OF WIND DAMAGE. THE BEST OPPORTUNITY FOR THIS MIGHT BE TODAY WITH
THE NAM FORECASTING 1500-2000 J/KG OF DOWNDRAFT CAPE. THE REST OF
THE MODEL RUN LOOKS QUIET IN TERMS OF WIND THREAT. MEAN STORM MOTION
IN THE NAM IS LESS THAN 10 KTS AND K INDICES OF 35 TO 40 IN ALL
MODELS WILL SUPPORT LOCALLY HEAVY RAINFALL.
THE MOISTURE WILL BE FEEDING NORTH THROUGH THE FCST AREA AROUND A
COOL CANADIAN HIGH PRESSURE SYSTEM CENTERED OVER THE MIDWEST. THIS
SHOULD LIMIT HIGHS TUESDAY AND WEDNESDAY TO THE UPPER 70S TO AROUND
80 AND LOWS IN THE UPPER 50S TO AROUND 60.
WEDNESDAY NIGHT THROUGH SUNDAY...
A SIGNIFICANT UPPER LEVEL TROF AND DEEP MOISTURE WILL PASS OVER THE
FCST AREA WEDNESDAY NIGHT AND PERHAPS THROUGH THURSDAY MORNING.
ADDITIONAL TSTM ACTIVITY IS EXPECTED WITH THIS WAVE. THEREAFTER THE
WRN U.S. RIDGE WILL AMPLIFY INTO THE NRN PLAINS. THE UPPER LEVEL
MOISTURE VANISHES AND A GRADUAL WARMING TREND DEVELOPS THROUGH
SUNDAY. BY SUNDAY H700 MB TEMPERATURES COULD RISE TO AROUND 14C AND
H10-5 THICKNESSES APPROACH 580DM. MEANWHILE K INDICES FALL OFF IN
THE ECM SOLN BUT REMAIN HIGH IN THE GFS...35-40C. THUS THE GFS
CONTINUES TO LACTATE WHILE THE ECM GOES DRY. CAP STRENGTH IS
RELATIVELY WEAK THROUGH SATURDAY...LESS THAN 12C SO ITS UNCLEAR IF
THE FCST AREA CAN REMAIN DRY THURSDAY AFTERNOON THROUGH SUNDAY WITH
FCST DEW POINTS IN THE 60S. SINCE THE FLOW ALOFT BECOMES ALMOST DUE
NORTH...SUBSIDENCE COULD MAINTAIN A DRY PATTERN.
TEMPERATURES RISE THROUGH THE 80S TO NEAR 90 BY SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1228 PM CDT MON AUG 12 2013
A TRICKY AVIATION FORECAST IS IN THE CARDS OVER THE NEXT 24 HOURS
ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. WEAK MID LEVEL FLOW AND
THE LACK OF A FRONTAL BOUNDARY WILL MAKE IT DIFFICULT TO PINPOINT
TIMING AND LOCATION OF THUNDERSTORMS TONIGHT. BOTH THE NAM AND GFS
SOLNS HAD SOME SIGNIFICANT INITIALIZATION ISSUES THIS MORNING AND
RELIED HEAVILY ON THE SREF AND HIRES RUC SOLNS FOR THE 18Z TAF
FCSTS. THAT BEING SAID...THINKING HERE IS THAT MID AND UPPER LEVEL
CLOUDINESS WILL BE ON THE INCREASE LATER THIS AFTERNOON AND THIS
EVENING AS CONVECTION DIES OFF TO THE WEST OF THE FORECAST AREA.
COVERAGE OF ANY ISOLATED TSRAS THIS EVENING WILL BE TOO SPARSE TO
INCLUDE IN THE 18Z TAFS. HOWEVER...HIGHER CONFIDENCE IN
THUNDERSTORMS CREEPS INTO THE FORECAST ON TUESDAY MORNING AS THE
SREF...GFS AND NAM SOLNS BEGIN TO COME INTO BETTER AGREEMENT WITH
TSRA CHANCES ACROSS WESTERN NEBRASKA. WILL HANDLE THIS THREAT FOR
TSRAS WITH A PROB 30 GROUP AT BOTH TERMINALS FOR TUESDAY MORNING.
CIGS OVER THE NEXT 24 HOURS WILL GENERALLY RANGE FROM 6000 TO 15000
FT AGL. THE EXCEPTION WILL BE AT THE KVTN TERMINAL...AS SOME 1500 TO
2500 FT AGL CIGS ARE POSSIBLE AT THE KVTN TERMINAL THROUGH MID
AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CLB
SYNOPSIS...CDC
SHORT TERM...POWER
LONG TERM...CDC
AVIATION...CLB
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
236 PM EDT MON AUG 12 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA LATER TONIGHT AND PASS THROUGH
THE REGION ON TUESDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS.
FAIR AND COOLER WEATHER WILL FOLLOW THE FRONT...WITH SLOWLY
MODERATING TEMPERATURES INTO LATE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
BATCH OF -SHRA OVER SW NY HAVING A TUFF TIME MAKING EWD PROGRESS
INTO CNTRL NY...BUT A FEW -SHRA WILL PRBLY WORK INTO THE SRN TIER
AND NE PA LATER THIS AFTN AND EVNG. BETTER CHCS FOR SHRA/TSRA WILL
COME LATER TNGT THROUGH MIDDAY TUESDAY AS A COLD FRONT PASSES THE
RGN. NAM HAS CDFNT JUST ENTERING THE FINGER LAKES AND WRN SRN TIER
BY 12Z...MOVG SEWD AND PASSING AVP ARND 19Z...AND SHOWS A WEAK
WAVE OF LOW PRES TRACKING ENEWD ALONG THE FNT WITH A PSN NEAR BGM
BY 15Z. GFS IS A FEW HRS SLOWER THAN THE NAM.
NAM SHOWS BEST AXIS OF QPF JUST N OF A LOW TRACKING ENEWD ALONG THE
FNT...FROM THE CNTRL SRN TIER AND SRN FINGER LAKES INTO THE WRN
MOHAWK VLY...WITH MAX QPF OF 1 TO 1.5 INCHES. THIS LOW IS NOT
EVIDENT IN THE OTHER MDLS. HOWEVER...BOTH THE NAM/GFS SHOW PRE-
FNTL PRECIPITABLE WATER RISING TO NEAR 1.5 INCHES. SUGGESTIONS OF
STRENGTHENING UPR LVL DVRGNC IN RR QUAD OF AN UPR LVL JET TMRW. SO
LOCALLY HEAVY RAINS ARE A POSSIBILITY AS THIS SYSTEM WORKS
THROUGH. GREATEST CAPES ON TUE WILL BE OVER NE PA BY MIDDAY PRBLY
MAXING OUT IN THE 500-750 J/KG RNG. SPC HAS SLGT RISK AREAS S AND
E OF THE FCST AREA AND LOOKS GOOD. HOWEVER...WE`LL HAVE TO MONITOR
FOR PSBLTY OF A FEW STRONG STORMS THERE ARND MIDDAY. CONDITIONS
SHOULD BE IMPROVING ACROSS MUCH OF CNTRL NY IN THE AFTN...SPCLY
OVER THE FINGER LAKES AND CNTRL SRN TIER.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
POTENT UPR LVL TROF...WHICH REMAINS WELL WEST OF THE INITIAL
CDFNT...MOVS INTO WRN/CNTRL NY TMRW EVNG...ACCOMPANIED BY A WEAK
2NDRY SFC TROF WHICH IS FCST TO BE OVER LOWER LAKE ONTARIO BY 00Z
WED. THESE FEATURES...IN COMBINATION WITH LAKE INFLUENCES
SUGGESTS SCT -SHRA ACRS PORTIONS OF CNTRL NY TMRW EVNG IN NNWLY
FLOW...ACTIVITY WHICH SHOULD DSPT LATE AT NGT AS MORE STABLE AND
DRIER AIR WORKS IN. NAM/GFS LOW LVL RH FIELDS AND FCST SKEW-T`S
SUGGESTS PTNL FOR LOW CLDS/STRATUS IN THIS COOLER NNW FLOW LATER TUE NGT
INTO EARLY WED MRNG. PROFILES ALSO SHOW THE LIKELIHOOD OF
DIURNALLY ENHANCED SCT-BKN CU OR STRATO-CU BOTH WED AND THU AFTN.
TEMPS WILL BE ON THE COOL SIDE WED...MODERATING TO MORE SEASONABLE
LVLS BY THU AFTN. CAN XPCT BREEZY CONDITIONS ON WED AS THE GTLAKES
HIGH BUILDS IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
1 PM MON UPDATE... ON THE LARGE-SCALE...THE TWO MAIN FIXTURES THIS
PD WILL BE A STRENGTHENING WRN ATLANTIC UPR RIDGE...AND A WRN
CONUS UPR RIDGE AXIS. IN BETWEEN THE TWO...A WEAKNESS IN THE HGT
FIELDS LOOKS TO EXIST...WITH A FLAT MEAN TROUGH AXIS IN PLACE FROM
THE TN VLY SWD TO THE GULF STATES. THE PRIMARY INFLUENCING SYSTEM FOR
NY/PA DURG THIS TIME FRAME SHOULD BE THE WRN ATLANTIC UPR
RIDGE...WITH A STG "BERMUDA HIGH" TYPE SFC ANTICYCLONE...EXTENDING
FROM THE WRN ATLANTIC...BACK OVER THE ERN STATES.
THIS SYNOPTIC PATN SEEMS FAVORABLE FOR A PROLONGED STRETCH OF DRY
WX ACRS OUR FA...ALG WITH SLOWLY WARMING TEMPS OVER TIME. THE
LATEST GFS/EC/WPC PROGS AGREE THAT THIS WILL INDEED BE THE CASE.
FROM THIS EARLY VANTAGE PT...IT APPEARS THAT THE FIRST REAL CHC
FOR ANY PCPN WON`T BE TIL SOMETIME EARLY NEXT WEEK (MON OR PERHAPS
BEYOND)...WHEN SOME GULF MOISTURE ATTEMPTS TO PUSH NWD. EVEN AT
THAT...WE`RE ONLY ADVERTISING SCHC-CHC POPS ATTM FROM LATE SUN NGT
INTO NEXT MON.
TEMPS WILL BE FAIRLY SEASONABLE MUCH OF THE PD...WITH HIGHS
STARTING OFF IN THE 70S THU...GRADUALLY MODERATING INTO THE LWR-
MIDDLE 80S BY LTR IN THE WEEKEND/NEXT WEEK.
PREV DISC... 230 AM MON UPDATE... NO CHANGE FROM PREVIOUS FCST AS
STRONG HIGH PRESSURE WILL ENSURE COOL AND FAIR WX THROUGH THE BULK
OF THE PERIOD. SOME HINTS AT INCREASING MOISTURE TOWARDS NEXT
WEEKEND WITH SHWRS/STORMS POSSIBLE BY SUN NGT/MON AS UPPER LOW
BEGINS LIFTING NORTH FROM THE OHIO/TENN VLYS AND SFC HIGH PRESSURE
BREAKS DOWN OVER NEW ENGLAND. WITH MAX JET ENERGY EXPECTED TO
REMAIN SOUTH OF THE REGION...BETTER CHANCES FOR SHWRS/STORMS WILL
EXIST FROM THE CENTRAL MID-ATLANTIC SOUTH. TEMPS SHOULD BEGIN
MODERATING TOWARDS THE END OF THE WEEK WITH UPPER 70S TO NEAR 80
POSSIBLE BY SATURDAY.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
18Z MON UPDATE... VFR CONDS SHOULD PERSIST AREA-WIDE THROUGH THE
EVE HRS...WITH A WEAKENING AREA OF CLDS/SHWRS LIKELY NOT PRODUCING
ANY RESTRICTIONS AS IT CROSSES SRN NY/NE PA FM ABT 21-03Z.
LTR TNT AND TUE...CONDS ARE EXPECTED TO DETERIORATE...AS A COLD
FRNT APPRCHS FROM THE NW...AND A SEPARATE WV MOVES THROUGH THE
DELMARVA RGN. IT IS ANTICIPATED THAT A BAND OF SHWRS...JUST AHD OF
THE COLD FRNT...WILL BEGIN TO IMPACT KSYR/KRME/KITH/KELM FROM
06-09Z...WITH A SEPARATE AREA OF SHWRS...ASSOCD WITH THE MORE SRN
SYSTEM...ALSO IMPACTING KAVP AT ABT THE SAME TIME. AT THIS
JUNCTURE...WE`LL GO WITH MVFR RESTRICTIONS. BRIEF IFR CONDS ARE
NOT OUT OF THE QUESTION IN HVYR SHWRS...BUT IT SEEMS LIKE THESE
EPISODES WILL BE BRIEF IN NATURE...AND HAVE THUS KEPT OUT OF THE
TERMINAL FCSTS ATTM.
ON TUE...SHWRS/EMBEDDED TSTMS SHOULD PROGRESS FROM NW-SE THROUGH
CNY/NE PA. AT KAVP...IT`S PROBABLE THAT TEMPORARY IMPROVEMENT WILL
TAKE PLACE AFTER 13-15Z...AS THE INITIAL AREA OF SHWRS MOVES
OUT...AND FRNTL SHWRS/TSTMS HOLD OFF TIL THE AFTN (AFTER 18Z).
ELSEWHERE (KSYR/KRME/KELM/KITH/BGM)...MVFR CONDS IN LWR
CIGS/SHWRS SHOULD PREVAIL. AT OUR NRN/WRN-MOST SITES
(KRME/KSYR/KELM)...FROPA MAY WELL TAKE PLACE FAST ENUF (BY ARND
16Z)...SO THAT DRIER AIR PUSHES IN AND IMPROVEMENT BACK TO VFR
OCCURS.
LGT/VRBL SFC WINDS INTO THIS EVE...WILL BECOME SRLY LATE TNT AT
5-10 KT. SW WINDS 5-10 KT ON TUE AM...SHOULD SHIFT INTO THE W AND NW
AFTER FROPA AT KSYR/KRME/KITH/KELM BY EARLY AFTN.
OUTLOOK...
TUE NGT...A PD OF MVFR CIGS PSBL...SPCLY ACRS CNY.
WED THRU SAT...MAINLY VFR. THE ONLY EXCEPTION WILL BE PSBL EARLY
AM VLY FOG AT KELM.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...CMG/MLJ
AVIATION...MLJ
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
233 PM EDT MON AUG 12 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA LATER TONIGHT AND PASS THROUGH
THE REGION IN TUESDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS.
FAIR AND COOLER WEATHER WILL FOLLOW THE FRONT...WITH SLOWLY
MODERATING TEMPERATURES INTO LATE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
BATCH OF -SHRA OVER SW NY HAVING A TUFF TIME MAKING EWD PROGRESS
INTO CNTRL NY...BUT A FEW -SHRA WILL PRBLY WORK INTO THE SRN TIER
AND NE PA LATER THIS AFTN AND EVNG. BETTER CHCS FOR SHRA/TSRA WILL
COME LATER TNGT THROUGH MIDDAY TUESDAY AS A COLD FRONT PASSES THE
RGN. NAM HAS CDFNT JUST ENTERING THE FINGER LAKES AND WRN SRN TIER
BY 12Z...MOVG SEWD AND PASSING AVP ARND 19Z...AND SHOWS A WEAK
WAVE OF LOW PRES TRACKING ENEWD ALONG THE FNT WITH A PSN NEAR BGM
BY 15Z. GFS IS A FEW HRS SLOWER THAN THE NAM.
NAM SHOWS BEST AXIS OF QPF JUST N OF A LOW TRACKING ENEWD ALONG THE
FNT...FROM THE CNTRL SRN TIER AND SRN FINGER LAKES INTO THE WRN
MOHAWK VLY...WITH MAX QPF OF 1 TO 1.5 INCHES. THIS LOW IS NOT
EVIDENT IN THE OTHER MDLS. HOWEVER...BOTH THE NAM/GFS SHOW PRE-
FNTL PRECIPITABLE WATER RISING TO NEAR 1.5 INCHES. SUGGESTIONS OF
STRENGTHENING UPR LVL DVRGNC IN RR QUAD OF AN UPR LVL JET TMRW. SO
LOCALLY HEAVY RAINS ARE A POSSIBILITY AS THIS SYSTEM WORKS
THROUGH. GREATEST CAPES ON TUE WILL BE OVER NE PA BY MIDDAY PRBLY
MAXING OUT IN THE 500-750 J/KG RNG. SPC HAS SLGT RISK AREAS S AND
E OF THE FCST AREA AND LOOKS GOOD. HOWEVER...WE`LL HAVE TO MONITOR
FOR PSBLTY OF A FEW STRONG STORMS THERE ARND MIDDAY. CONDITIONS
SHOULD BE IMPROVING ACROSS MUCH OF CNTRL NY IN THE AFTN...SPCLY
OVER THE FINGER LAKES AND CNTRL SRN TIER.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
POTENT UPR LVL TROF...WHICH REMAINS WELL WEST OF THE INITIAL
CDFNT...MOVS INTO WRN/CNTRL NY TMRW EVNG...ACCOMPANIED BY A WEAK
2NDRY SFC TROF WHICH IS FCST TO BE OVER LOWER LAKE ONTARIO BY 00Z
WED. THESE FEATURES...IN COMBINATION WITH LAKE INFLUENCES
SUGGESTS SCT -SHRA ACRS PORTIONS OF CNTRL NY TMRW EVNG IN NNWLY
FLOW...ACTIVITY WHICH SHOULD DSPT LATE AT NGT AS MORE STABLE AND
DRIER AIR WORKS IN. NAM/GFS LOW LVL RH FIELDS AND FCST SKEW-T`S
SUGGESTS PTNL FOR LOW CLDS/STRATUS IN THIS COOLER NNW FLOW LATER TUE NGT
INTO EARLY WED MRNG. PROFILES ALSO SHOW THE LIKELIHOOD OF
DIURNALLY ENHANCED SCT-BKN CU OR STRATO-CU BOTH WED AND THU AFTN.
TEMPS WILL BE ON THE COOL SIDE WED...MODERATING TO MORE SEASONABLE
LVLS BY THU AFTN. CAN XPCT BREEZY CONDITIONS ON WED AS THE GTLAKES
HIGH BUILDS IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
1 PM MON UPDATE... ON THE LARGE-SCALE...THE TWO MAIN FIXTURES THIS
PD WILL BE A STRENGTHENING WRN ATLANTIC UPR RIDGE...AND A WRN
CONUS UPR RIDGE AXIS. IN BETWEEN THE TWO...A WEAKNESS IN THE HGT
FIELDS LOOKS TO EXIST...WITH A FLAT MEAN TROUGH AXIS IN PLACE FROM
THE TN VLY SWD TO THE GULF STATES. THE PRIMARY INFLUENCING SYSTEM FOR
NY/PA DURG THIS TIME FRAME SHOULD BE THE WRN ATLANTIC UPR
RIDGE...WITH A STG "BERMUDA HIGH" TYPE SFC ANTICYCLONE...EXTENDING
FROM THE WRN ATLANTIC...BACK OVER THE ERN STATES.
THIS SYNOPTIC PATN SEEMS FAVORABLE FOR A PROLONGED STRETCH OF DRY
WX ACRS OUR FA...ALG WITH SLOWLY WARMING TEMPS OVER TIME. THE
LATEST GFS/EC/WPC PROGS AGREE THAT THIS WILL INDEED BE THE CASE.
FROM THIS EARLY VANTAGE PT...IT APPEARS THAT THE FIRST REAL CHC
FOR ANY PCPN WON`T BE TIL SOMETIME EARLY NEXT WEEK (MON OR PERHAPS
BEYOND)...WHEN SOME GULF MOISTURE ATTEMPTS TO PUSH NWD. EVEN AT
THAT...WE`RE ONLY ADVERTISING SCHC-CHC POPS ATTM FROM LATE SUN NGT
INTO NEXT MON.
TEMPS WILL BE FAIRLY SEASONABLE MUCH OF THE PD...WITH HIGHS
STARTING OFF IN THE 70S THU...GRADUALLY MODERATING INTO THE LWR-
MIDDLE 80S BY LTR IN THE WEEKEND/NEXT WEEK.
PREV DISC... 230 AM MON UPDATE... NO CHANGE FROM PREVIOUS FCST AS
STRONG HIGH PRESSURE WILL ENSURE COOL AND FAIR WX THROUGH THE BULK
OF THE PERIOD. SOME HINTS AT INCREASING MOISTURE TOWARDS NEXT
WEEKEND WITH SHWRS/STORMS POSSIBLE BY SUN NGT/MON AS UPPER LOW
BEGINS LIFTING NORTH FROM THE OHIO/TENN VLYS AND SFC HIGH PRESSURE
BREAKS DOWN OVER NEW ENGLAND. WITH MAX JET ENERGY EXPECTED TO
REMAIN SOUTH OF THE REGION...BETTER CHANCES FOR SHWRS/STORMS WILL
EXIST FROM THE CENTRAL MID-ATLANTIC SOUTH. TEMPS SHOULD BEGIN
MODERATING TOWARDS THE END OF THE WEEK WITH UPPER 70S TO NEAR 80
POSSIBLE BY SATURDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
18Z MON UPDATE... VFR CONDS SHOULD PERSIST AREA-WIDE THROUGH THE
EVE HRS...WITH A WEAKENING AREA OF CLDS/SHWRS LIKELY NOT PRODUCING
ANY RESTRICTIONS AS IT CROSSES SRN NY/NE PA FM ABT 21-03Z.
LTR TNT AND TUE...CONDS ARE EXPECTED TO DETERIORATE...AS A COLD
FRNT APPRCHS FROM THE NW...AND A SEPARATE WV MOVES THROUGH THE
DELMARVA RGN. IT IS ANTICIPATED THAT A BAND OF SHWRS...JUST AHD OF
THE COLD FRNT...WILL BEGIN TO IMPACT KSYR/KRME/KITH/KELM FROM
06-09Z...WITH A SEPARATE AREA OF SHWRS...ASSOCD WITH THE MORE SRN
SYSTEM...ALSO IMPACTING KAVP AT ABT THE SAME TIME. AT THIS
JUNCTURE...WE`LL GO WITH MVFR RESTRICTIONS. BRIEF IFR CONDS ARE
NOT OUT OF THE QUESTION IN HVYR SHWRS...BUT IT SEEMS LIKE THESE
EPISODES WILL BE BRIEF IN NATURE...AND HAVE THUS KEPT OUT OF THE
TERMINAL FCSTS ATTM.
ON TUE...SHWRS/EMBEDDED TSTMS SHOULD PROGRESS FROM NW-SE THROUGH
CNY/NE PA. AT KAVP...IT`S PROBABLE THAT TEMPORARY IMPROVEMENT WILL
TAKE PLACE AFTER 13-15Z...AS THE INITIAL AREA OF SHWRS MOVES
OUT...AND FRNTL SHWRS/TSTMS HOLD OFF TIL THE AFTN (AFTER 18Z).
ELSEWHERE (KSYR/KRME/KELM/KITH/BGM)...MVFR CONDS IN LWR
CIGS/SHWRS SHOULD PREVAIL. AT OUR NRN/WRN-MOST SITES
(KRME/KSYR/KELM)...FROPA MAY WELL TAKE PLACE FAST ENUF (BY ARND
16Z)...SO THAT DRIER AIR PUSHES IN AND IMPROVEMENT BACK TO VFR
OCCURS.
LGT/VRBL SFC WINDS INTO THIS EVE...WILL BECOME SRLY LATE TNT AT
5-10 KT. SW WINDS 5-10 KT ON TUE AM...SHOULD SHIFT INTO THE W AND NW
AFTER FROPA AT KSYR/KRME/KITH/KELM BY EARLY AFTN.
OUTLOOK...
TUE NGT...A PD OF MVFR CIGS PSBL...SPCLY ACRS CNY.
WED THRU SAT...MAINLY VFR. THE ONLY EXCEPTION WILL BE PSBL EARLY
AM VLY FOG AT KELM.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...CMG/MLJ
AVIATION...MLJ
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
210 PM EDT MON AUG 12 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA LATER TONIGHT AND PASS THROUGH
THE REGION IN TUESDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS.
FAIR AND COOLER WEATHER WILL FOLLOW THE FRONT...WITH SLOWLY
MODERATING TEMPERATURES INTO LATE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
BATCH OF -SHRA OVER SW NY HAVING A TUFF TIME MAKING EWD PROGRESS
INTO CNTRL NY...BUT A FEW -SHRA WILL PRBLY WORK INTO THE SRN TIER
AND NE PA LATER THIS AFTN AND EVNG. BETTER CHCS FOR SHRA/TSRA WILL
COME LATER TNGT THROUGH MIDDAY TUESDAY AS A COLD FRONT PASSES THE
RGN. NAM HAS CDFNT JUST ENTERING THE FINGER LAKES AND WRN SRN TIER
BY 12Z...MOVG SEWD AND PASSING AVP ARND 19Z...AND SHOWS A WEAK
WAVE OF LOW PRES TRACKING ENEWD ALONG THE FNT WITH A PSN NEAR BGM
BY 15Z. GFS IS A FEW HRS SLOWER THAN THE NAM.
NAM SHOWS BEST AXIS OF QPF JUST N OF A LOW TRACKING ENEWD ALONG THE
FNT...FROM THE CNTRL SRN TIER AND SRN FINGER LAKES INTO THE WRN
MOHAWK VLY...WITH MAX QPF OF 1 TO 1.5 INCHES. THIS LOW IS NOT
EVIDENT IN THE OTHER MDLS. HOWEVER...BOTH THE NAM/GFS SHOW PRE-
FNTL PRECIPITABLE WATER RISING TO NEAR 1.5 INCHES. SUGGESTIONS OF
STRENGTHENING UPR LVL DVRGNC IN RR QUAD OF AN UPR LVL JET TMRW. SO
LOCALLY HEAVY RAINS ARE A POSSIBILITY AS THIS SYSTEM WORKS
THROUGH. GREATEST CAPES ON TUE WILL BE OVER NE PA BY MIDDAY PRBLY
MAXING OUT IN THE 500-750 J/KG RNG. SPC HAS SLGT RISK AREAS S AND
E OF THE FCST AREA AND LOOKS GOOD. HOWEVER...WE`LL HAVE TO MONITOR
FOR PSBLTY OF A FEW STRONG STORMS THERE ARND MIDDAY. CONDITIONS
SHOULD BE IMPROVING ACROSS MUCH OF CNTRL NY IN THE AFTN...SPCLY
OVER THE FINGER LAKES AND CNTRL SRN TIER.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
POTENT UPR LVL TROF...WHICH REMAINS WELL WEST OF THE INITIAL
CDFNT...MOVS INTO WRN/CNTRL NY TMRW EVNG...ACCOMPANIED BY A WEAK
2NDRY SFC TROF WHICH IS FCST TO BE OVER LOWER LAKE ONTARIO BY 00Z
WED. THESE FEATURES...IN COMBINATION WITH LAKE INFLUENCES
SUGGESTS SCT -SHRA ACRS PORTIONS OF CNTRL NY TMRW EVNG IN NNWLY
FLOW...ACTIVITY WHICH SHOULD DSPT LATE AT NGT AS MORE STABLE AND
DRIER AIR WORKS IN. NAM/GFS LOW LVL RH FIELDS AND FCST SKEW-T`S
SUGGESTS PTNL FOR LOW CLDS/STRATUS IN THIS COOLER NNW FLOW LATER TUE NGT
INTO EARLY WED MRNG. PROFILES ALSO SHOW THE LIKELIHOOD OF
DIURNALLY ENHANCED SCT-BKN CU OR STRATO-CU BOTH WED AND THU AFTN.
TEMPS WILL BE ON THE COOL SIDE WED...MODERATING TO MORE SEASONABLE
LVLS BY THU AFTN. CAN XPCT BREEZY CONDITIONS ON WED AS THE GTLAKES
HIGH BUILDS IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
1 PM MON UPDATE... ON THE LARGE-SCALE...THE TWO MAIN FIXTURES THIS
PD WILL BE A STRENGTHENING WRN ATLANTIC UPR RIDGE...AND A WRN
CONUS UPR RIDGE AXIS. IN BETWEEN THE TWO...A WEAKNESS IN THE HGT
FIELDS LOOKS TO EXIST...WITH A FLAT MEAN TROUGH AXIS IN PLACE FROM
THE TN VLY SWD TO THE GULF STATES. THE PRIMARY INFLUENCING SYSTEM FOR
NY/PA DURG THIS TIME FRAME SHOULD BE THE WRN ATLANTIC UPR
RIDGE...WITH A STG "BERMUDA HIGH" TYPE SFC ANTICYCLONE...EXTENDING
FROM THE WRN ATLANTIC...BACK OVER THE ERN STATES.
THIS SYNOPTIC PATN SEEMS FAVORABLE FOR A PROLONGED STRETCH OF DRY
WX ACRS OUR FA...ALG WITH SLOWLY WARMING TEMPS OVER TIME. THE
LATEST GFS/EC/WPC PROGS AGREE THAT THIS WILL INDEED BE THE CASE.
FROM THIS EARLY VANTAGE PT...IT APPEARS THAT THE FIRST REAL CHC
FOR ANY PCPN WON`T BE TIL SOMETIME EARLY NEXT WEEK (MON OR PERHAPS
BEYOND)...WHEN SOME GULF MOISTURE ATTEMPTS TO PUSH NWD. EVEN AT
THAT...WE`RE ONLY ADVERTISING SCHC-CHC POPS ATTM FROM LATE SUN NGT
INTO NEXT MON.
TEMPS WILL BE FAIRLY SEASONABLE MUCH OF THE PD...WITH HIGHS
STARTING OFF IN THE 70S THU...GRADUALLY MODERATING INTO THE LWR-
MIDDLE 80S BY LTR IN THE WEEKEND/NEXT WEEK.
PREV DISC... 230 AM MON UPDATE... NO CHANGE FROM PREVIOUS FCST AS
STRONG HIGH PRESSURE WILL ENSURE COOL AND FAIR WX THROUGH THE BULK
OF THE PERIOD. SOME HINTS AT INCREASING MOISTURE TOWARDS NEXT
WEEKEND WITH SHWRS/STORMS POSSIBLE BY SUN NGT/MON AS UPPER LOW
BEGINS LIFTING NORTH FROM THE OHIO/TENN VLYS AND SFC HIGH PRESSURE
BREAKS DOWN OVER NEW ENGLAND. WITH MAX JET ENERGY EXPECTED TO
REMAIN SOUTH OF THE REGION...BETTER CHANCES FOR SHWRS/STORMS WILL
EXIST FROM THE CENTRAL MID-ATLANTIC SOUTH. TEMPS SHOULD BEGIN
MODERATING TOWARDS THE END OF THE WEEK WITH UPPER 70S TO NEAR 80
POSSIBLE BY SATURDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS EXPECTED ACROSS THE REGION TODAY WITH LIGHT W TO
SW WINDS BETWEEN 5-10 KTS. EXPECT SCT-BKN CU DEVELOPMENT LATER
THIS MORNING/EARLY AFTERNOON WITH BASES CENTERED BETWEEN 4 AND 6
KFT. ISOLATED SHWRS AND STORMS WILL BE POSSIBLE ACROSS THE REGION
TODAY HOWEVER COVERAGE WILL REMAIN FAIRLY ISOLATED THUS NO MENTION
IN MORNING FCST PACKAGE. SHWRS/ISOLATED STORMS TO BECOME MORE
WIDESPREAD AFTER 06Z AS A COLD FRONT APPROACHES. FOR NOW...EXPECT
SHWR ACTIVITY TO BEGIN WORKING INTO THE ELM/SYR/ITH SHORTLY AFTER
06Z...RME BY 08Z...AND BGM BY 09Z. FOR NOW...BEST COVERAGE LIKELY
HOLD OFF UNTIL ROUGHLY 10-12Z AT AVP. AS RAIN MOVES IN...EXPECT
PERIODIC MVFR CONDITIONS.
OUTLOOK...
TUE...MVFR IN SHRA/TSRA.
WED/THU/FRI...VFR...BRIEF IFR PSBL AT ELM IN EARLY MRNG VLY FOG.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
LONG TERM...CMG/MLJ
AVIATION...MLJ
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
205 PM EDT MON AUG 12 2013
.SYNOPSIS...
A COLD FRONT WILL APPROACH THE AREA LATER TONIGHT AND PASS THROUGH
THE REGION IN TUESDAY...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS.
FAIR AND COOLER WEATHER WILL FOLLOW THE FRONT...WITH SLOWLY
MODERATING TEMPERATURES INTO LATE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
BATCH OF -SHRA OVER SW NY HAVING A TUFF TIME MAKING EWD PROGRESS
INTO CNTRL NY...BUT A FEW -SHRA WILL PRBLY WORK INTO THE SRN TIER
AND NE PA LATER THIS AFTN AND EVNG. BETTER CHCS FOR SHRA/TSRA WILL
COME LATER TNGT THROUGH MIDDAY TUESDAY AS A COLD FRONT PASSES THE
RGN. NAM HAS CDFNT JUST ENTERING THE FINGER LAKES AND WRN SRN TIER
BY 12Z...MOVG SEWD AND PASSING AVP ARND 19Z...AND SHOWS A WEAK
WAVE OF LOW PRES TRACKING ENEWD ALONG THE FNT WITH A PSN NEAR BGM
BY 15Z. GFS IS A FEW HRS SLOWER THAN THE NAM.
NAM SHOWS BEST AXIS OF QPF JUST N OF A LOW TRACKING ENEWD ALONG THE
FNT...FROM THE CNTRL SRN TIER AND SRN FINGER LAKES INTO THE WRN
MOHAWK VLY...WITH MAX QPF OF 1 TO 1.5 INCHES. THIS LOW IS NOT
EVIDENT IN THE OTHER MDLS. HOWEVER...BOTH THE NAM/GFS SHOW PRE-
FNTL PRECIPITABLE WATER RISING TO NEAR 1.5 INCHES. SUGGESTIONS OF
STRENGTHENING UPR LVL DVRGNC IN RR QUAD OF AN UPR LVL JET TMRW. SO
LOCALLY HEAVY RAINS ARE A POSSIBILITY AS THIS SYSTEM WORKS
THROUGH. GREATEST CAPES ON TUE WILL BE OVER NE PA BY MIDDAY PRBLY
MAXING OUT IN THE 500-750 J/KG RNG. SPC HAS SLGT RISK AREAS S AND
E OF THE FCST AREA AND LOOKS GOOD. HOWEVER...WE`LL HAVE TO MONITOR
FOR PSBLTY OF A FEW STRONG STORMS THERE ARND MIDDAY. CONDITIONS
SHOULD BE IMPROVING ACROSS MUCH OF CNTRL NY IN THE AFTN...SPCLY
OVER THE FINGER LAKES AND CNTRL SRN TIER.
$$
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
POTENT UPR LVL TROF...WHICH REMAINS WELL WEST OF THE INITIAL
CDFNT...MOVS INTO WRN/CNTRL NY TMRW EVNG...ACCOMPANIED BY A WEAK
2NDRY SFC TROF WHICH IS FCST TO BE OVER LOWER LAKE ONTARIO BY 00Z
WED. THESE FEATURES...IN COMBINATION WITH LAKE INFLUENCES
SUGGESTS SCT -SHRA ACRS PORTIONS OF CNTRL NY TMRW EVNG IN NNWLY
FLOW...ACTIVITY WHICH SHOULD DSPT LATE AT NGT AS MORE STABLE AND
DRIER AIR WORKS IN. NAM/GFS LOW LVL RH FIELDS AND FCST SKEW-T`S
SUGGESTS PTNL FOR LOW CLDS/STRATUS IN THIS COOLER NNW FLOW LATER TUE NGT
INTO EARLY WED MRNG. PROFILES ALSO SHOW THE LIKELIHOOD OF
DIURNALLY ENHANCED SCT-BKN CU OR STRATO-CU BOTH WED AND THU AFTN.
TEMPS WILL BE ON THE COOL SIDE WED...MODERATING TO MORE SEASONABLE
LVLS BY THU AFTN. CAN XPCT BREEZY CONDITIONS ON WED AS THE GTLAKES
HIGH BUILDS IN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
1 PM MON UPDATE... ON THE LARGE-SCALE...THE TWO MAIN FIXTURES THIS
PD WILL BE A STRENGTHENING WRN ATLANTIC UPR RIDGE...AND A WRN
CONUS UPR RIDGE AXIS. IN BETWEEN THE TWO...A WEAKNESS IN THE HGT
FIELDS LOOKS TO EXIST...WITH A FLAT MEAN TROUGH AXIS IN PLACE FROM
THE TN VLY SWD TO THE GULF STATES. THE PRIMARY INFLUENCING SYSTEM FOR
NY/PA DURG THIS TIME FRAME SHOULD BE THE WRN ATLANTIC UPR
RIDGE...WITH A STG "BERMUDA HIGH" TYPE SFC ANTICYCLONE...EXTENDING
FROM THE WRN ATLANTIC...BACK OVER THE ERN STATES.
THIS SYNOPTIC PATN SEEMS FAVORABLE FOR A PROLONGED STRETCH OF DRY
WX ACRS OUR FA...ALG WITH SLOWLY WARMING TEMPS OVER TIME. THE
LATEST GFS/EC/WPC PROGS AGREE THAT THIS WILL INDEED BE THE CASE.
FROM THIS EARLY VANTAGE PT...IT APPEARS THAT THE FIRST REAL CHC
FOR ANY PCPN WON`T BE TIL SOMETIME EARLY NEXT WEEK (MON OR PERHAPS
BEYOND)...WHEN SOME GULF MOISTURE ATTEMPTS TO PUSH NWD. EVEN AT
THAT...WE`RE ONLY ADVERTISING SCHC-CHC POPS ATTM FROM LATE SUN NGT
INTO NEXT MON.
TEMPS WILL BE FAIRLY SEASONABLE MUCH OF THE PD...WITH HIGHS
STARTING OFF IN THE 70S THU...GRADUALLY MODERATING INTO THE LWR-
MIDDLE 80S BY LTR IN THE WEEKEND/NEXT WEEK.
PREV DISC... 230 AM MON UPDATE... NO CHANGE FROM PREVIOUS FCST AS
STRONG HIGH PRESSURE WILL ENSURE COOL AND FAIR WX THROUGH THE BULK
OF THE PERIOD. SOME HINTS AT INCREASING MOISTURE TOWARDS NEXT
WEEKEND WITH SHWRS/STORMS POSSIBLE BY SUN NGT/MON AS UPPER LOW
BEGINS LIFTING NORTH FROM THE OHIO/TENN VLYS AND SFC HIGH PRESSURE
BREAKS DOWN OVER NEW ENGLAND. WITH MAX JET ENERGY EXPECTED TO
REMAIN SOUTH OF THE REGION...BETTER CHANCES FOR SHWRS/STORMS WILL
EXIST FROM THE CENTRAL MID-ATLANTIC SOUTH. TEMPS SHOULD BEGIN
MODERATING TOWARDS THE END OF THE WEEK WITH UPPER 70S TO NEAR 80
POSSIBLE BY SATURDAY.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS EXPECTED ACROSS THE REGION TODAY WITH LIGHT W TO
SW WINDS BETWEEN 5-10 KTS. EXPECT SCT-BKN CU DEVELOPMENT LATER
THIS MORNING/EARLY AFTERNOON WITH BASES CENTERED BETWEEN 4 AND 6
KFT. ISOLATED SHWRS AND STORMS WILL BE POSSIBLE ACROSS THE REGION
TODAY HOWEVER COVERAGE WILL REMAIN FAIRLY ISOLATED THUS NO MENTION
IN MORNING FCST PACKAGE. SHWRS/ISOLATED STORMS TO BECOME MORE
WIDESPREAD AFTER 06Z AS A COLD FRONT APPROACHES. FOR NOW...EXPECT
SHWR ACTIVITY TO BEGIN WORKING INTO THE ELM/SYR/ITH SHORTLY AFTER
06Z...RME BY 08Z...AND BGM BY 09Z. FOR NOW...BEST COVERAGE LIKELY
HOLD OFF UNTIL ROUGHLY 10-12Z AT AVP. AS RAIN MOVES IN...EXPECT
PERIODIC MVFR CONDITIONS.
OUTLOOK...
TUE...MVFR IN SHRA/TSRA.
WED/THU/FRI...VFR...BRIEF IFR PSBL AT ELM IN EARLY MRNG VLY FOG.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.
&&
$$
LONG TERM...CMG/MLJ
AVIATION...CMG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1240 PM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 1240 PM CDT MON AUG 12 2013
SEEING THE CUMULUS AREA ACROSS NORTHWEST MN EXPANDING A LITTLE
FURTHER SOUTH NOW. WITH THE MORNING SUNSHINE ARE GETTING SOME
WEAK INSTABILITY FORMING THERE TOO. WILL KEEP THE ISOLATED SHOWER
MENTION ALTHOUGH WILL DELAY IT BY A FEW MORE HOURS. CONFIDENCE
REMAINS PRETTY LOW ON SEEING ANY SHOWER DEVELOPMENT AND IT WOULD
BE MINIMAL IF ANY DO FORM.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
CHALLENGE FOR THE FORECAST TODAY WILL BE SHOWERS IF ANY ALONG THE
BACK DOOR COLD FRONT SLIDING SOUTH OUT OF MANITOBA...CURRENTLY
NORTH OF WINNIPEG. CLOUDS ASSOCIATED WITH FRONT MAY CAUSE SOME
UNCERTAINTY WITH TEMPS HOWEVER CURRENT TIMING OF FROPA WILL STILL
GIVE MUCH OF THE AREA GOOD SOLAR THIS AFTERNOON. ALSO MOISTURE IS
LIMITED WITH MOSTLY A MID LEVEL BAND OF CLOUDS WHICH WILL BE FAIRLY
NARROW. WILL MAINTAIN HIGH TEMPS THIS AFTERNOON SIMILAR TO
YESTERDAYS MID TO UPPER 70S.
AS FOR POPS AND COVERAGE...IF ANYTHING ISOLATED SHOWERS AT BEST.
BEST FORCING REMAINS EAST CLOSER TO VORT LOBE AND SFC LOW PRESSURE
ACROSS THE NORTHERN GREAT LAKES. EC QPFS PAINT SOME VERY LIGHT
AMOUNTS ACROSS THE NORTHERN VALLEY AND UPPER DEVILS LAKE BASIN.
HAVE LEFT THIS AREA DRY AND KEPT THE SLIGHT POPS IN NW MN FOR THE
LATE MORNING AND INTO THE AFTERNOON. THIS AREA IS WHERE THE 00Z
GFS...06Z NAM AND THE 06Z HRRR HAVE SOME LIGHT QPF.
1025MB CANADIAN HIGH PRESSURE TO BUILD IN BEHIND FROPA THIS EVENING
AND CENTER OVER S MANITOBA BY TUESDAY MORNING. NORTHERLY WINDS LOWER
PWATS DOWN TO AROUND HALF AN INCH...CAUSING CLEAR SKIES AND COOL
TEMPS MONDAY NIGHT INTO TUESDAY MORNING. HAVE KEPT FOG MENTION
OUT OF THE FORECAST WITH NO RECENT PRECIP BUT WOULD NOT BE
SURPRISED TO SEE SOME SHALLOW GROUND FOG DEVELOP. WILL KEEP OUT OF
GRIDS FOR NOW. HIGH TEMPS TUESDAY VERY SIMILAR TO MONDAY A DEGREE
OR TOW COOLER AS THERMAL PROFILE MAY BE A TOUCH LOWER THAN MONDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
TUESDAY NIGHT THRU WEDNESDAY NIGHT...THE SFC HIGH PRESSURE SYSTEM
SLOWLY DRIFTS ACROSS THE FA AS 500MB CONFLUENT FLOW CONTINUES.
LITTLE TO NO CHANGE IN THERMAL PROFILE. HIGHS IN THE 70S WITH
LOWS IN THE UPPER 40S NORTH AND LOW 50S SOUTH.
THURSDAY THROUGH SUNDAY...LONG RANGE MODELS CONTINUE TO POINT TO
A SIGNIFICANT WARM UP FOR THE EXTENDED PERIOD. THERE APPEARS TO BE
HIGHER CONFIDENCE THAT THE RIDGE AXIS OVER THE ROCKIES WILL
TRANSLATE EASTWARD OVER THE NORTHERN PLAINS LATE THIS WEEK INTO
THE WEEKEND. THE WARMING TREND MAY PERSIST WELL INTO NEXT WEEK AND
BE THE MOST PROLONGED STRETCH OF ABOVE NORMAL TEMPERATURES FOR
THIS PART OF THE COUNTRY SO FAR THIS SUMMER. THE TIME PERIOD FOR
SIGNIFICANT AND WIDESPREAD PRECIPITATION NOW LOOKS LIKE IT MAY
HOLD OFF UNTIL NEXT SUNDAY. IT APPEARS THAT WE MAY EXPERIENCE SOME
MCS ACTIVITY DUE TO COMPLEXES RIDING OVER THE RIDGE AXIS WHICH
SHOULD BE IN PLACE OVER THE AREA. DUE TO THE INCREASINGLY DRY
CONDITIONS OVER THE REGION AS INDICATED BY THE LATEST DROUGHT
MONITOR...ANY SUBSTANTIAL RAINFALL WOULD BE A WELCOME RELIEF.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1240 PM CDT MON AUG 12 2013
SOME CU POSSIBLE THIS AFTERNOON ALONG WITH NORTH WINDS AROUND 10
KNOTS. HIGH PRESSURE WILL LEAD TO MOSTLY CLEAR SKY AND LIGHT WINDS
TONIGHT INTO TUESDAY.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...GODON
SHORT TERM...JK
LONG TERM...BRAMER/JK
AVIATION...TG
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
938 AM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 938 AM CDT MON AUG 12 2013
ONLY THING REALLY IN QUESTION FOR TODAY IS THE POSSIBILITY OF ANY
SHOWER DEVELOPMENT ACROSS OUR MN FA. NOT MUCH CLOUD COVER ACROSS
THE AREA NOW BUT THERE IS A BIT OF CUMULUS DEVELOPING ALONG THE
CANADIAN BORDER FROM THE LAKE OF THE WOODS INTO THE MN ARROWHEAD.
THERE IS SOME WEAK SHORT WAVE ENERGY DROPPING THRU OUR EAST TODAY
ALONG WITH SOME COOLER 500MB TEMPS. ALONG WITH THE MORNING SFC
HEATING THIS MAY BE ENOUGH TO SET OFF SOME AFTERNOON SHOWERS.
HOWEVER SOME OF THE NEW HIGH RES MODELS ARE LOOKING DRY. EITHER
WAY IT WOULD NOT BE A BIG DEAL AS FAR AS RAIN AMOUNTS. PREVIOUS
FORECAST HAD THE SHOWERS DEVELOPING BY MID MORNING AND WILL PUSH
THAT BACK TO THE AFTERNOON AND SEE WHAT HAPPENS. REST OF FORECAST
UNCHANGED.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
CHALLENGE FOR THE FORECAST TODAY WILL BE SHOWERS IF ANY ALONG THE
BACK DOOR COLD FRONT SLIDING SOUTH OUT OF MANITOBA...CURRENTLY
NORTH OF WINNIPEG. CLOUDS ASSOCIATED WITH FRONT MAY CAUSE SOME
UNCERTAINTY WITH TEMPS HOWEVER CURRENT TIMING OF FROPA WILL STILL
GIVE MUCH OF THE AREA GOOD SOLAR THIS AFTERNOON. ALSO MOISTURE IS
LIMITED WITH MOSTLY A MID LEVEL BAND OF CLOUDS WHICH WILL BE FAIRLY
NARROW. WILL MAINTAIN HIGH TEMPS THIS AFTERNOON SIMILAR TO
YESTERDAYS MID TO UPPER 70S.
AS FOR POPS AND COVERAGE...IF ANYTHING ISOLATED SHOWERS AT BEST.
BEST FORCING REMAINS EAST CLOSER TO VORT LOBE AND SFC LOW PRESSURE
ACROSS THE NORTHERN GREAT LAKES. EC QPFS PAINT SOME VERY LIGHT
AMOUNTS ACROSS THE NORTHERN VALLEY AND UPPER DEVILS LAKE BASIN.
HAVE LEFT THIS AREA DRY AND KEPT THE SLIGHT POPS IN NW MN FOR THE
LATE MORNING AND INTO THE AFTERNOON. THIS AREA IS WHERE THE 00Z
GFS...06Z NAM AND THE 06Z HRRR HAVE SOME LIGHT QPF.
1025MB CANADIAN HIGH PRESSURE TO BUILD IN BEHIND FROPA THIS EVENING
AND CENTER OVER S MANITOBA BY TUESDAY MORNING. NORTHERLY WINDS LOWER
PWATS DOWN TO AROUND HALF AN INCH...CAUSING CLEAR SKIES AND COOL
TEMPS MONDAY NIGHT INTO TUESDAY MORNING. HAVE KEPT FOG MENTION
OUT OF THE FORECAST WITH NO RECENT PRECIP BUT WOULD NOT BE
SURPRISED TO SEE SOME SHALLOW GROUND FOG DEVELOP. WILL KEEP OUT OF
GRIDS FOR NOW. HIGH TEMPS TUESDAY VERY SIMILAR TO MONDAY A DEGREE
OR TOW COOLER AS THERMAL PROFILE MAY BE A TOUCH LOWER THAN MONDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
TUESDAY NIGHT THRU WEDNESDAY NIGHT...THE SFC HIGH PRESSURE SYSTEM
SLOWLY DRIFTS ACROSS THE FA AS 500MB CONFLUENT FLOW CONTINUES.
LITTLE TO NO CHANGE IN THERMAL PROFILE. HIGHS IN THE 70S WITH
LOWS IN THE UPPER 40S NORTH AND LOW 50S SOUTH.
THURSDAY THROUGH SUNDAY...LONG RANGE MODELS CONTINUE TO POINT TO
A SIGNIFICANT WARM UP FOR THE EXTENDED PERIOD. THERE APPEARS TO BE
HIGHER CONFIDENCE THAT THE RIDGE AXIS OVER THE ROCKIES WILL
TRANSLATE EASTWARD OVER THE NORTHERN PLAINS LATE THIS WEEK INTO
THE WEEKEND. THE WARMING TREND MAY PERSIST WELL INTO NEXT WEEK AND
BE THE MOST PROLONGED STRETCH OF ABOVE NORMAL TEMPERATURES FOR
THIS PART OF THE COUNTRY SO FAR THIS SUMMER. THE TIME PERIOD FOR
SIGNIFICANT AND WIDESPREAD PRECIPITATION NOW LOOKS LIKE IT MAY
HOLD OFF UNTIL NEXT SUNDAY. IT APPEARS THAT WE MAY EXPERIENCE SOME
MCS ACTIVITY DUE TO COMPLEXES RIDING OVER THE RIDGE AXIS WHICH
SHOULD BE IN PLACE OVER THE AREA. DUE TO THE INCREASINGLY DRY
CONDITIONS OVER THE REGION AS INDICATED BY THE LATEST DROUGHT
MONITOR...ANY SUBSTANTIAL RAINFALL WOULD BE A WELCOME RELIEF.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 648 AM CDT MON AUG 12 2013
VFR TODAY WITH NORTH WINDS 5 TO 15 KTS. MAYBE A ISO SHOWER IN NW
MN...HAVE LEFT OUT OF TAFS FOR NOW AS CHANCES APPEARS TO BE VERY
REMOTE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...GODON
SHORT TERM...JK
LONG TERM...BRAMER/JK
AVIATION...JK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
648 AM CDT MON AUG 12 2013
.UPDATE...
ISSUED AT 648 AM CDT MON AUG 12 2013
REMOVED ANY FOG MENTION FOR THE MORNING WITH THIS UPDATE. NO OTHER
CHANGES AS FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
CHALLENGE FOR THE FORECAST TODAY WILL BE SHOWERS IF ANY ALONG THE
BACK DOOR COLD FRONT SLIDING SOUTH OUT OF MANITOBA...CURRENTLY
NORTH OF WINNIPEG. CLOUDS ASSOCIATED WITH FRONT MAY CAUSE SOME
UNCERTAINTY WITH TEMPS HOWEVER CURRENT TIMING OF FROPA WILL STILL
GIVE MUCH OF THE AREA GOOD SOLAR THIS AFTERNOON. ALSO MOISTURE IS
LIMITED WITH MOSTLY A MID LEVEL BAND OF CLOUDS WHICH WILL BE FAIRLY
NARROW. WILL MAINTAIN HIGH TEMPS THIS AFTERNOON SIMILAR TO
YESTERDAYS MID TO UPPER 70S.
AS FOR POPS AND COVERAGE...IF ANYTHING ISOLATED SHOWERS AT BEST.
BEST FORCING REMAINS EAST CLOSER TO VORT LOBE AND SFC LOW PRESSURE
ACROSS THE NORTHERN GREAT LAKES. EC QPFS PAINT SOME VERY LIGHT
AMOUNTS ACROSS THE NORTHERN VALLEY AND UPPER DEVILS LAKE BASIN.
HAVE LEFT THIS AREA DRY AND KEPT THE SLIGHT POPS IN NW MN FOR THE
LATE MORNING AND INTO THE AFTERNOON. THIS AREA IS WHERE THE 00Z
GFS...06Z NAM AND THE 06Z HRRR HAVE SOME LIGHT QPF.
1025MB CANADIAN HIGH PRESSURE TO BUILD IN BEHIND FROPA THIS EVENING
AND CENTER OVER S MANITOBA BY TUESDAY MORNING. NORTHERLY WINDS LOWER
PWATS DOWN TO AROUND HALF AN INCH...CAUSING CLEAR SKIES AND COOL
TEMPS MONDAY NIGHT INTO TUESDAY MORNING. HAVE KEPT FOG MENTION
OUT OF THE FORECAST WITH NO RECENT PRECIP BUT WOULD NOT BE
SURPRISED TO SEE SOME SHALLOW GROUND FOG DEVELOP. WILL KEEP OUT OF
GRIDS FOR NOW. HIGH TEMPS TUESDAY VERY SIMILAR TO MONDAY A DEGREE
OR TOW COOLER AS THERMAL PROFILE MAY BE A TOUCH LOWER THAN MONDAY.
.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 350 AM CDT MON AUG 12 2013
TUESDAY NIGHT THRU WEDNESDAY NIGHT...THE SFC HIGH PRESSURE SYSTEM
SLOWLY DRIFTS ACROSS THE FA AS 500MB CONFLUENT FLOW CONTINUES.
LITTLE TO NO CHANGE IN THERMAL PROFILE. HIGHS IN THE 70S WITH
LOWS IN THE UPPER 40S NORTH AND LOW 50S SOUTH.
THURSDAY THROUGH SUNDAY...LONG RANGE MODELS CONTINUE TO POINT TO
A SIGNIFICANT WARM UP FOR THE EXTENDED PERIOD. THERE APPEARS TO BE
HIGHER CONFIDENCE THAT THE RIDGE AXIS OVER THE ROCKIES WILL
TRANSLATE EASTWARD OVER THE NORTHERN PLAINS LATE THIS WEEK INTO
THE WEEKEND. THE WARMING TREND MAY PERSIST WELL INTO NEXT WEEK AND
BE THE MOST PROLONGED STRETCH OF ABOVE NORMAL TEMPERATURES FOR
THIS PART OF THE COUNTRY SO FAR THIS SUMMER. THE TIME PERIOD FOR
SIGNIFICANT AND WIDESPREAD PRECIPITATION NOW LOOKS LIKE IT MAY
HOLD OFF UNTIL NEXT SUNDAY. IT APPEARS THAT WE MAY EXPERIENCE SOME
MCS ACTIVITY DUE TO COMPLEXES RIDING OVER THE RIDGE AXIS WHICH
SHOULD BE IN PLACE OVER THE AREA. DUE TO THE INCREASINGLY DRY
CONDITIONS OVER THE REGION AS INDICATED BY THE LATEST DROUGHT
MONITOR...ANY SUBSTANTIAL RAINFALL WOULD BE A WELCOME RELIEF.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 648 AM CDT MON AUG 12 2013
VFR TODAY WITH NORTH WINDS 5 TO 15 KTS. MAYBE A ISO SHOWER IN NW
MN... HAVE LEFT OUT OF TAFS FOR NOW AS CHANCES APPEARS TO BE VERY
REMOTE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
UPDATE...JK
SHORT TERM...JK
LONG TERM...BRAMER/JK
AVIATION...JK
AREA FORECAST DISCUSSION
NWS TULSA OK
621 AM CDT MON AUG 12 2013
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
ONGOING CONVECTION CURRENTLY SPREADING INTO NE OK WILL CONTINUE
EASTWARD WITH PERIODIC FLIGHT IMPACTS FOR NE OK AND EVENTUALLY FAR
NW SITES. EVOLUTION OF CONVECTION THROUGH THE REMAINDER OF THE
AFTERNOON AND THROUGH TONIGHT IS UNCERTAIN...HOWEVER EXPECTATIONS
ARE THAT THE BULK OF THE HEAVIEST PRECIP WILL BE ALONG AND NORTH
OF A SLOW MOVING FRONTAL BOUNDARY WHICH WILL BE NEARER NORTHER
LOCATIONS THROUGH TONIGHT. FORECAST WILL CALL FOR LONG PERIODS OF
VCTS AND/OR PREVAILING TSRA AND ALLOW FOR LATER FORECASTS TO
HIGHLIGHT PERIODS OF HIGHER CONFIDENCE FLIGHT IMPACTS.
&&
.PREV DISCUSSION... /ISSUED 311 AM CDT MON AUG 12 2013/
DISCUSSION...
THE MAIN CONCERN WITH THE FORECAST THIS MORNING IS THE POTENTIAL FOR
A PROLONGED PERIOD OF INTERMITTENT HEAVY RAINFALL OVER THE NEXT
COUPLE OF DAYS... WITH THE POSSIBILITY OF RENEWED FLOODING ISSUES
ACROSS MUCH OF THE AREA.
CONVECTIVE ACTIVITY CURRENTLY ONGOING ACROSS WESTERN AND CENTRAL
OKLAHOMA IS FORECAST TO SPREAD EASTWARD ACROSS THE FORECAST AREA
DURING THE DAY TODAY. BOTH THE LOCAL WRF AND THE HRRR DEPICT THIS AS
REMAINING MOSTLY SCATTERED IN NATURE. HOWEVER... ANY HEAVIER STORMS
OR TRAINING OF CELLS COULD QUICKLY LEAD TO LOCALIZED FLOODING...
GIVEN THE AMOUNTS OF RAINFALL THE AREA HAS RECEIVED OF LATE. THERE
WILL ALSO BE THE POTENTIAL FOR STORMS TO BECOME STRONG TO SEVERE
DURING THE DAY TODAY GIVEN THE AMOUNT OF INSTABILITY AND SHEAR PRESENT.
THE MAIN THREAT FOR WIDESPREAD HEAVY RAINFALL WILL BEGIN OVERNIGHT
TONIGHT. SEVERAL ROUNDS OF HEAVY THUNDERSTORMS WILL LIKELY AFFECT
THE REGION THROUGH TUESDAY UNTIL A COLD FRONT SWEEPS SOUTHWARD
THROUGH THE REGION BRINGING DRIER AIR INTO THE AREA. A FLASH FLOOD
WATCH WILL BECOME EFFECTIVE THIS MORNING THROUGH 0Z TUESDAY.
DEPENDING ON THE EVOLUTION OF THE EVENT AND PROGRESS OF THE FRONT...
THIS WATCH MAY EVENTUALLY NEED TO BE EXTENDED IN TIME INTO TUESDAY
EVENING.
SCATTERED PRECIPITATION MAY LAST THROUGH THE DAY WEDNESDAY. HOWEVER...
AFTER THAT... DRY AND MILD CONDITIONS WILL PREVAIL INTO AND THROUGH
THE UPCOMING WEEKEND. SOME OF THE COOLEST OVERNIGHT LOWS OF THE
SEASON WILL OCCUR THURSDAY THROUGH SATURDAY MORNINGS. READINGS IN
NORTHWEST ARKANSAS ARE EXPECTED TO DIP INTO THE 50S... WITH LOW TO
MID 60S ACROSS MUCH OF THE REST OF THE FORECAST AREA. DAYTIME HIGH
TEMPERATURES WILL CONTINUE TO RUN BELOW SEASONAL AVERAGES... AND
WITH DEWPOINTS IN THE UPPER 50S TO LOWER 60S SHOULD FEEL QUITE
UNSEASONABLY PLEASANT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 89 72 84 70 / 60 40 60 50
FSM 91 73 86 71 / 60 60 70 70
MLC 95 73 89 71 / 20 50 70 70
BVO 88 70 83 68 / 80 40 50 50
FYV 85 68 83 67 / 80 70 60 50
BYV 83 68 83 65 / 80 70 50 40
MKO 90 72 84 70 / 70 40 70 60
MIO 86 69 85 66 / 80 30 40 40
F10 92 73 85 70 / 30 40 70 70
HHW 95 75 94 73 / 10 30 30 50
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...FLASH FLOOD WATCH UNTIL 7 PM TUESDAY FOR OKZ054-OKZ055-OKZ056-
OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-OKZ062-OKZ063-OKZ064-
OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-OKZ070-OKZ071-OKZ072-
OKZ073-OKZ074-OKZ075-OKZ076.
AR...FLASH FLOOD WATCH UNTIL 7 PM TUESDAY FOR ARZ001-ARZ002-ARZ010-
ARZ011-ARZ019-ARZ020-ARZ029.
&&
$$
AVIATION...07
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
333 PM EDT MON AUG 12 2013
.SYNOPSIS...
PARTLY SUNNY...WARM...AND INCREASINGLY HUMID AIR WILL COVER MUCH OF
THE REGION LATE THIS AFTERNOON AND TONIGHT. SHOWERS WILL MOVE ACROSS
THE NORTHERN MOUNTAINS LATE THIS AFTERNOON WITH ADDITIONAL SHOWERS
AND SCATTERED THUNDERSTORMS DEVELOPING ACROSS THE WESTERN HALF OF
THE STATE OVERNIGHT AHEAD OF AN APPROACHING STRONG COLD FRONT. THE
FRONT WILL PUSH THROUGH THE STATE ON TUESDAY. IN THE WAKE OF THE
COLD FRONT A LARGE AREA OF CANADIAN HIGH PRESSURE WILL BUILD
SOUTHEAST INTO THE STATE. THIS HIGH WILL BRING SEVERAL PLEASANT BUT
RELATIVELY COOL DAYS AND NIGHTS. THE ASSOCIATED DEEP TROUGH AND COOL
AIR ALOFT WILL MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND.
TEMPERATURES SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
WEAK RIDGING RESULTED IN A DECENT AMOUNT OF SUNSHINE WITH LIGHT WIND
ACROSS MOST OF THE FCST AREA THIS AFTERNOON. WEAK NEGATIVE...OR
NEUTRAL LLVL THETA-E ADVECTION ACCOMPANYING THIS HIGH ALONG WITH
STABLE MID LEVELS CAPPED ANY DEPTH TO THE SCT-BKN CU OR STRATO CU
CLOUDS SO FAR.
THE EXCEPTION WAS ACROSS THE NORTHWEST MOUNTAINS WHERE A THICK
LAYERED CLOUD SHIELD AND SHOWERS SPREAD QUICKLY EAST INTO THE KBFD
BY 18Z. THERE IS A HIGH LIKELIHOOD OF SHOWERS ACRS OUR NW ZONES
DURING THE MID AFTERNOON THROUGH EARLY EVENING...TAPERING TO
SCATTERED SHOWERS ACROSS THE MTNS TO THE NE OF KIPT. RAINFALL
AMOUNTS OF 0.1 - 0.2 WERE PAINTED IN ACROSS OUR NRN MTN ZONES WITH
THE HIGHEST AMOUNTS INVOF KBFD AND PTS WEST.
TEMPERATURES LATE THIS AFTERNOON ACROSS MOST OF CENTRAL PENN AND THE
SUSQ REGION WILL BE CLOSE TO NORMAL HIGHS FOR MID AUGUST...EXCEPT
FOR SLIGHTLY BELOW NORMAL TEMPS ACROSS THE NW MTNS WHERE MORE
EXTENSIVE CLOUD COVER AND NUMEROUS SHOWERS WILL OVERSPREAD THE
REGION THIS AFTERNOON.
FOR TONIGHT...THE LATEST HRRR AND 12/15Z OPERATIONAL AND ENSEMBLE
RUNS INDICATE INCREASING COVERAGE OF SHOWERS AND EMBEDDED TSRA
/MAINLY AFTER MIDNIGHT/ AS THE THERMALLY DIRECT CELL /OF A JET MAX
JUST TO OUR NORTH/ AND ASSOCIATED SWRLY LLJ ENHANCES UVVEL. LOWEST
POPS FOR SHOWERS WILL BE ACROSS THE MIDDLE AND LOWER SUSQ
VALLEY...AND CONFINED MAINLY TO THE 06-12Z TIMEFRAME.
RAINFALL AMOUNTS WILL VARY FROM AROUND 0.50 INCH NEAR KBFD...TO LESS
THAN 0.10 NEAR AND TO THE SE OF KMDT.
LOW TEMPS WILL BE ON THE MILD SIDE AHEAD OF THE CFRONT...AND IN THE
U50S TO LOWER 60S ACROSS THE MTNS...WITH MID TO UPPER 60S ACROSS THE
CENTRAL AND SE VALLEYS.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION DURING THE MORNING
TO EARLY AFTERNOON HOURS. TIMING OF THE FRONT AND DEPARTING UPPER
LEVEL FORCING TO OUR NORTHEAST SHOULD LIMIT THE THREAT FOR
SIGNIFICANT/DEEP CONVECTION IN MOST PLACES...EXCEPT FOR PERHAPS ONE
OR TWO STRONG TSRA ACROSS OUR FAR EAST AFTER 16Z RIGHT NEAR THE
CFRONT.
PLENTY OF LOW CLOUDS SHOULD FORM THEN LINGER IN THE COOLER/MOIST
UPSLOPE FLOW IN THE WAKE OF THE FRONT ACROSS THE ALLEGHENY PLATEAU
/KJST TO KBFD/...KEEPING TEMPS IN THE U60S TO LOWER 70S.
BKN...LAYERED CU AND ALTO CU WILL OCCUR ELSEWHERE WITH SCATTERED TO
NUMEROUS SHOWERS FOR SEVERAL HOURS ALONG AND IN ADVANCE OF THE
FRONT. HIGHS WILL BE BETWEEN 75-80F THROUGHOUT THE CENTRAL AND
SOUTHERN VALLEYS.
ADDITIONAL RAINFALL AMOUNTS TUESDAY WILL LIKELY AVERAGE UNDER 0.25
INCH IN MOST PLACES...BUT LOCATIONS SEEING A TSRA ACROSS THE SUSQ
VALLEY MAY SEE LOCALLY OVER 0.50 GIVEN THE NW EDGE OF 1.5-1.75 INCH
PWATS SLIDING ACROSS THE AREA AHEAD OF THE FRONT DURING THE
MORNING/MIDDAY HOURS.
TUESDAY AFTERNOON WILL FEATURE A DRYING TREND WITH A 10-20 MPH WEST
TO NW BREEZE AS A WELL-DEFINED DRY SLOT MOVES OVER THE REGION WITH
PWATS STEADILY DECREASING /TO BELOW 0.75 INCH ACROSS THE NW MTNS/
THROUGH THE AFTERNOON AND EVENING HOURS.
THE SOUTHERN...TAIL END OF A MID LEVEL THERMAL TROUGH WITH STEEP
850-500 MB LAPSE RATES WILL BRING A SEVERAL HOUR PERIOD OF CLOUDS
AND A LOW CHC FOR SHOWERS ACROSS THE NRN TIER COUNTIES LATER TUESDAY
NIGHT. RAINFALL AMOUNTS WILL BE LIGHT.
OTHERWISE...LOOK FOR GENERALLY PARTLY CLOUDY CONDITIONS WITH A
NORTHWEST BREEZE GRADUALLY DIMINISHING TO UNDER 7 KTS AFTER MIDNIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
OVERVIEW...THE LATEST ARRAY OF GUIDANCE SHOWS THE LARGE SCALE MEAN
FLOW OVER THE CONUS TRENDING/TRANSITIONING TOWARD A MORE TYPICAL
MID-AUGUST PATTERN WITH THE UPPER-LEVEL WESTERLIES SHIFTING NWD TO
LATITUDES ALONG AND NORTH OF THE US-CANADIAN BORDER BY EARLY NEXT
WEEK. THE PRONOUNCED/DEEP UPPER TROUGH GRIPPING THE NORTHEAST AND
MID-ATLANTIC STATES EARLY IN THE PERIOD SHOULD WEAKEN WITH
TIME...AS THE REMAINING NEGATIVE HEIGHT ANOMALY DRIFTS SWWD INTO
THE LWR MS RVR VLY PER THE 12Z GEFS MEAN. AT THE SFC...A LARGE
DOME OF HIGH PRESSURE /WITH ORIGINS OVER CENTRAL CANADA/ WILL
SPREAD SEWD FROM THE UPPER PLAINS ACROSS THE GRT LKS/OH VLY AND
TAKE UP RESIDENCE IN THE NEW ENGLAND AREA OVER THE WEEKEND. A WAVY
SFC FRONT OVER THE SE STATES IS PROGGED TO LIFT BACK NWD TOWARD
THE CAROLINA COAST/SRN MID-ATLC REGION BY SAT-MON.
HIGHLIGHTS...DRY WX SHOULD PREVAIL THROUGH THE MAJORITY OF THE
MEDIUM RANGE COURTESY OF HIGH PRES MIGRATING SLOWLY EWD FROM THE
UPPER MIDWEST TO THE NEW ENGLAND STATES. PWATS STAY BELOW NORMAL
THROUGH FRIDAY...RESULTING IN COMFORTABLE HUMIDITY AND COOL
NIGHTTIME TEMPS WITH LOWS IN THE 40S/50S. SOME UPPER 30S REMAIN
POSSIBLE OVER THE NRN TIER. CLEAR/CALM/COOL NIGHTS SHOULD ALSO
LEAD TO PREDAWN AND EARLY MORNING FOG IN THE VALLEYS. DAYTIME
HIGHS WILL AVERAGE NEAR TO BELOW NORMAL. A GRADUALLY MOISTENING
EAST-SOUTHEAST LOW LEVEL FLOW FAVORS AN INCREASE IN SKY COVER AND
LOW CHC FOR SHOWERS LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK.
THE 12Z GFS AND 00Z ECMWF HANDLE THE EAST COAST FRONTAL BOUNDARY
REASONABLY WELL...WITH A CONSENSUS MULTI-MODEL/MOS/HPC SUPERBLEND
SUPPORTING THE HIGHEST POPS AROUND 19 AUGUST.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
EXPECT MAINLY VFR CONDITIONS TO PERSIST THROUGH THE REST OF TODAY
AND THROUGH THIS EVENING AT ALL TAF SITES WITH THE LONE EXCEPTION OF
KBFD...WHERE MVFR VSBYS AND PERHAPS PERIODS OF MVFR CIGS WILL
ACCOMPANY A LARGE AREA OF SHOWERS THAT HAVE RECENTLY SPREAD INTO THE
REGION FROM LAKE ERIE AND PTS WEST.
OUTSIDE OF THE NW MTNS...CONVECTION WILL BE ISOLATED AND BRIEF AS
WEAK RIDGING AT THE SFC AND ALOFT MOVES OVERHEAD.
WARM ADVECTION AND INCREASING DEEP LAYER MOISTURE AHEAD OF A STRONG
COLD FRONT WILL BRING DETERIORATING CIGS AND VSBYS LATE THIS EVENING
INTO THE MORNING HOURS TUESDAY. MVFR WITH POCKETS OF IFR WILL
ACCOMPANY SCTD TO NUMEROUS SHOWERS AND ISOLATED TSRA.
CIGS NEAR AND IN THE WAKE OF THE COLD FRONT WILL LIKELY DROP INTO
THE LIFR RANGE FOR AT LEAST A FEW HOURS TUESDAY MORNING /FROM 10Z ON
IN KBFD AND KJST/ AS THE COOL MOIST AIR IS LIFTED OVER THE WRN PENN
MTNS.
THE STRONG COLD FRONT WILL MOVE ACROSS THE REGION DURING THE MORNING
AND EARLY AFTERNOON HOURS TUESDAY. EXPECT BANDS OF SHOWERS AND
THUNDERSTORMS TO FORM. DYNAMICS LAG THE FRONT SOME...BUT STILL SOME
CONCERN FOR BRIEF...STRONG WIND GUSTS WITH ANY STORMS...ESP ACROSS
THE SUSQ RIVER VALLEY.
NORTHWEST BREEZE OF 10-15 KTS SUSTAINED FOLLOWS THE CFRONT TUESDAY
AFTERNOON AND EVENING BEFORE SUBSIDING A BIT TUESDAY NIGHT.
WINDY ON WED...AS DEEPER/COLDER AIR WORKS SOUTHWARD.
LOOKING AT DRY CONDITIONS AFT WED.
OUTLOOK...
WED-SAT...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...STEINBUGL
AVIATION...LAMBERT
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
308 PM EDT MON AUG 12 2013
.SYNOPSIS...
PARTLY SUNNY...WARM...AND INCREASINGLY HUMID AIR WILL COVER MUCH OF
THE REGION LATE THIS AFTERNOON AND TONIGHT. SHOWERS WILL MOVE ACROSS
THE NORTHERN MOUNTAINS LATE THIS AFTERNOON WITH ADDITIONAL SHOWERS
AND SCATTERED THUNDERSTORMS DEVELOPING ACROSS THE WESTERN HALF OF
THE STATE OVERNIGHT AHEAD OF AN APPROACHING STRONG COLD FRONT. THE
FRONT WILL PUSH THROUGH THE STATE ON TUESDAY. IN THE WAKE OF THE
COLD FRONT A LARGE AREA OF CANADIAN HIGH PRESSURE WILL BUILD
SOUTHEAST INTO THE STATE. THIS HIGH WILL BRING SEVERAL PLEASANT BUT
RELATIVELY COOL DAYS AND NIGHTS. THE ASSOCIATED DEEP TROUGH AND COOL
AIR ALOFT WILL MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND.
TEMPERATURES SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAK RIDGING RESULTED IN A DECENT AMOUNT OF SUNSHINE WITH LIGHT WIND
ACROSS MOST OF THE FCST AREA THIS AFTERNOON. WEAK NEGATIVE...OR
NEUTRAL LLVL THETA-E ADVECTION ACCOMPANYING THIS HIGH ALONG WITH
STABLE MID LEVELS CAPPED ANY DEPTH TO THE SCT-BKN CU OR STRATO CU
CLOUDS SO FAR.
THE EXCEPTION WAS ACROSS THE NORTHWEST MOUNTAINS WHERE A THICK
LAYERED CLOUD SHIELD AND SHOWERS SPREAD QUICKLY EAST INTO THE KBFD
BY 18Z. THERE IS A HIGH LIKELIHOOD OF SHOWERS ACRS OUR NW ZONES
DURING THE MID AFTERNOON THROUGH EARLY EVENING...TAPERING TO
SCATTERED SHOWERS ACROSS THE MTNS TO THE NE OF KIPT. RAINFALL
AMOUNTS OF 0.1 - 0.2 WERE PAINTED IN ACROSS OUR NRN MTN ZONES WITH
THE HIGHEST AMOUNTS INVOF KBFD AND PTS WEST.
TEMPERATURES LATE THIS AFTERNOON ACROSS MOST OF CENTRAL PENN AND THE
SUSQ REGION WILL BE CLOSE TO NORMAL HIGHS FOR MID AUGUST...EXCEPT
FOR SLIGHTLY BELOW NORMAL TEMPS ACROSS THE NW MTNS WHERE MORE
EXTENSIVE CLOUD COVER AND NUMEROUS SHOWERS WILL OVERSPREAD THE
REGION THIS AFTERNOON.
FOR TONIGHT...THE LATEST HRRR AND 12/15Z OPERATIONAL AND ENSEMBLE
RUNS INDICATE INCREASING COVERAGE OF SHOWERS AND EMBEDDED TSRA
/MAINLY AFTER MIDNIGHT/ AS THE THERMALLY DIRECT CELL /OF A JET MAX
JUST TO OUR NORTH/ AND ASSOCIATED SWRLY LLJ ENHANCES UVVEL. LOWEST
POPS FOR SHOWERS WILL BE ACROSS THE MIDDLE AND LOWER SUSQ
VALLEY...AND CONFINED MAINLY TO THE 06-12Z TIMEFRAME.
RAINFALL AMOUNTS WILL VARY FROM AROUND 0.50 INCH NEAR KBFD...TO LESS
THAN 0.10 NEAR AND TO THE SE OF KMDT.
LOW TEMPS WILL BE ON THE MILD SIDE AHEAD OF THE CFRONT...AND IN THE
U50S TO LOWER 60S ACROSS THE MTNS...WITH MID TO UPPER 60S ACROSS THE
CENTRAL AND SE VALLEYS.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION DURING THE MORNING
TO EARLY AFTERNOON HOURS. TIMING OF THE FRONT AND DEPARTING UPPER
LEVEL FORCING TO OUR NORTHEAST SHOULD LIMIT THE THREAT FOR
SIGNIFICANT/DEEP CONVECTION IN MOST PLACES...EXCEPT FOR PERHAPS ONE
OR TWO STRONG TSRA ACROSS OUR FAR EAST AFTER 16Z RIGHT NEAR THE
CFRONT.
PLENTY OF LOW CLOUDS SHOULD FORM THEN LINGER IN THE COOLER/MOIST
UPSLOPE FLOW IN THE WAKE OF THE FRONT ACROSS THE ALLEGHENY PLATEAU
/KJST TO KBFD/...KEEPING TEMPS IN THE U60S TO LOWER 70S.
BKN...LAYERED CU AND ALTO CU WILL OCCUR ELSEWHERE WITH SCATTERED TO
NUMEROUS SHOWERS FOR SEVERAL HOURS ALONG AND IN ADVANCE OF THE
FRONT. HIGHS WILL BE BETWEEN 75-80F THROUGHOUT THE CENTRAL AND
SOUTHERN VALLEYS.
ADDITIONAL RAINFALL AMOUNTS TUESDAY WILL LIKELY AVERAGE UNDER 0.25
INCH IN MOST PLACES...BUT LOCATIONS SEEING A TSRA ACROSS THE SUSQ
VALLEY MAY SEE LOCALLY OVER 0.50 GIVEN THE NW EDGE OF 1.5-1.75 INCH
PWATS SLIDING ACROSS THE AREA AHEAD OF THE FRONT DURING THE
MORNING/MIDDAY HOURS.
TUESDAY AFTERNOON WILL FEATURE A DRYING TREND WITH A 10-20 MPH WEST
TO NW BREEZE AS A WELL-DEFINED DRY SLOT MOVES OVER THE REGION WITH
PWATS STEADILY DECREASING /TO BELOW 0.75 INCH ACROSS THE NW MTNS/
THROUGH THE AFTERNOON AND EVENING HOURS.
THE SOUTHERN...TAIL END OF A MID LEVEL THERMAL TROUGH WITH STEEP
850-500 MB LAPSE RATES WILL BRING A SEVERAL HOUR PERIOD OF CLOUDS
AND A LOW CHC FOR SHOWERS ACROSS THE NRN TIER COUNTIES LATER TUESDAY
NIGHT. RAINFALL AMOUNTS WILL BE LIGHT.
OTHERWISE...LOOK FOR GENERALLY PARTLY CLOUDY CONDITIONS WITH A
NORTHWEST BREEZE GRADUALLY DIMINISHING TO UNDER 7 KTS AFTER MIDNIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
POST FRONTAL THROUGH THURSDAY WITH A DRY AND COOL /FOR AUGUST/
PATTERN WITH ROCKY MOUNTAIN UPPER RIDGE AND DOWNSTREAM LONG WAVE
TROF FROM EASTERN CANADA TO THE MID ATLANTIC REGION. BOTH TUESDAY
AND WEDNESDAY MORNINGS LOOK VERY COOL ESPECIALLY ALONG THE
NORTHERN ZONES. FLOW TURNS SW BY FRIDAY AND THE WEEKEND FOR MILDER
TEMPERATURES AND A RETURN OF HIGHER HUMIDITY`S.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
EXPECT MAINLY VFR CONDITIONS TO PERSIST THROUGH THE REST OF TODAY
AND THROUGH THIS EVENING AT ALL TAF SITES WITH THE LONE EXCEPTION OF
KBFD...WHERE MVFR VSBYS AND PERHAPS PERIODS OF MVFR CIGS WILL
ACCOMPANY A LARGE AREA OF SHOWERS THAT HAVE RECENTLY SPREAD INTO THE
REGION FROM LAKE ERIE AND PTS WEST.
OUTSIDE OF THE NW MTNS...CONVECTION WILL BE ISOLATED AND BRIEF AS
WEAK RIDGING AT THE SFC AND ALOFT MOVES OVERHEAD.
WARM ADVECTION AND INCREASING DEEP LAYER MOISTURE AHEAD OF A STRONG
COLD FRONT WILL BRING DETERIORATING CIGS AND VSBYS LATE THIS EVENING
INTO THE MORNING HOURS TUESDAY. MVFR WITH POCKETS OF IFR WILL
ACCOMPANY SCTD TO NUMEROUS SHOWERS AND ISOLATED TSRA.
CIGS NEAR AND IN THE WAKE OF THE COLD FRONT WILL LIKELY DROP INTO
THE LIFR RANGE FOR AT LEAST A FEW HOURS TUESDAY MORNING /FROM 10Z ON
IN KBFD AND KJST/ AS THE COOL MOIST AIR IS LIFTED OVER THE WRN PENN
MTNS.
THE STRONG COLD FRONT WILL MOVE ACROSS THE REGION DURING THE MORNING
AND EARLY AFTERNOON HOURS TUESDAY. EXPECT BANDS OF SHOWERS AND
THUNDERSTORMS TO FORM. DYNAMICS LAG THE FRONT SOME...BUT STILL SOME
CONCERN FOR BRIEF...STRONG WIND GUSTS WITH ANY STORMS...ESP ACROSS
THE SUSQ RIVER VALLEY.
NORTHWEST BREEZE OF 10-15 KTS SUSTAINED FOLLOWS THE CFRONT TUESDAY
AFTERNOON AND EVENING BEFORE SUBSIDING A BIT TUESDAY NIGHT.
WINDY ON WED...AS DEEPER/COLDER AIR WORKS SOUTHWARD.
LOOKING AT DRY CONDITIONS AFT WED.
OUTLOOK...
WED-SAT...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...ROSS
AVIATION...LAMBERT
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
736 AM EDT MON AUG 12 2013
.SYNOPSIS...
LOOK FOR A MILD AND INCREASINGLY HUMID DAY TODAY ACROSS THE
REGION...AHEAD OF THE ARRIVAL OF A STRONG COLD FRONT PASSAGE ON
TUESDAY. THERE WILL BE A COUPLE WEAK WEATHER DISTURBANCES MOVING
ACROSS THE AREA WHICH COULD TOUCH OFF BRIEF SHOWERS AND
THUNDERSTORMS TODAY...BUT MOST OF THE AREA WILL BE FREE OF
SIGNIFICANT RAINFALL. BEHIND THE COLD FRONT ON TUESDAY...ABNORMALLY
COOL DRY AIR SHOULD OVERTAKE THE REGION...PROVIDING SEVERAL
PLEASANT BUT RELATIVELY COOL DAYS. THE DEEP TROUGH AND COOL AIR
MODIFY AND WEAKEN FRIDAY AND INTO THE COMING WEEKEND. TEMPERATURES
SHOULD TREND BACK TOWARD NORMAL FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
GENERAL DECREASE IN ACTIVITY THE LAST COUPLE HOURS...ACTIVITY
CONFINED TO SE QUARTER OF THE CWA. STORMS HAVE PRODUCED HEAVY
DOWNPOURS BUT MOVING JUST FAST ENOUGH TO PRECLUDE ANY FLOODING.
SCAP1 IN SCHUYLKILL COUNTY REPORTED .47 IN 35 MINUTES EARLIER THIS
MORNING. LATEST RUC AND HRRR SHOWS MOST OF THE CONVECTION
TAPERING OFF IN THE NEXT COUPLE HOURS. AFTER LOW CLOUDS DIMINISH
THIS MORNING THE REGION WILL SEE VARIABLE CLOUDS WITH A SLIGHT
CHANCE OF SHOWERS OR THUNDERSHOWERS...WITH THE HIGHEST CHANCES
OVER THE NW AND SE PORTIONS OF THE CWA...BUT SIMILAR TO
SUNDAY...MOST OF THE REGION WILL MISS OUT ON ANY SIGNIFICANT
RAINFALL. TEMPERATURES WILL BE CLOSE TO AVERAGE...THOUGH IT WILL
BE MORE HUMID AHEAD OF THE APPROACHING FRONT ARRIVING ON TUESDAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
THE STRONG FRONTAL SYSTEM WILL BECOME THE PRIMARY WEATHER FOCUS.
FRONTAL TIMING SUGGESTS CHANCE RAIN AND THUNDER COMES UP AFTER
MIDNIGHT IN WESTERN AREAS MOVING EASTWARD WITH TIME DURING
OVERNIGHT INTO TUESDAY MORNING. TIMING OF FRONTAL PASSAGE COULD
BE SUCH THAT TUESDAY AFTERNOON COULD TURN OUT DRIER...AND FORECAST
SHOWS POPS LOWERING IN THE SECOND HALF OF AFTERNOON WEST TO EAST.
QPF LOOKS RATHER LIGHT WITH PW PLUME NOT ALL THAT IMPRESSIVE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
POST FRONTAL THROUGH THURSDAY WITH A DRY AND COOL /FOR AUGUST/
PATTERN WITH ROCKY MOUNTAIN UPPER RIDGE AND DOWNSTREAM LONG WAVE
TROF FROM EASTERN CANADA TO THE MID ATLANTIC REGION. BOTH TUESDAY
AND WEDNESDAY MORNINGS LOOK VERY COOL ESPECIALLY ALONG THE
NORTHERN ZONES. FLOW TURNS SW BY FRIDAY AND THE WEEKEND FOR MILDER
TEMPERATURES AND A RETURN OF HIGHER HUMIDITY`S.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
FOG STARTING TO LIFT...SHOULD BE GONE BY 14Z.
WIDE RANGE OF CONDITIONS. UNV WENT CLEAR AROUND 5 AM...THEN
DENSE FOG FOR A BRIEF TIME.
MORE DENSE FOG TO THE SOUTH. VAD WINDS SUGGEST COOL AIR LESS
THAN 6000 DEEP THE LAST FEW DAYS.
AS BEEN THE CASE THIS SUMMER...SHOWERS FORM ALMOST EVERY DAY.
CURRENT ACTIVITY IS NOW MAINLY EAST OF OUR AREA.
BY MID MORNING...EXPECT MAINLY VFR CONDITIONS. THERE WILL STILL
BE A CHC OF SHOWERS AND PERHAPS A FEW THUNDERTORMS ACROSS THE
SOUTH THIS AFT AND EVENING.
AT THE SAME TIME...SOME SHOWERS AND STORMS COULD FORM
ACROSS NORTHERN PA LATER TODAY. OVERALL A COMPLEX PATTERN.
STRONG COLD FRONT TO MOVE ACROSS THE REGION LATE TUESDAY.
EXPECT BANDS OF SHOWERS AND THUNDERSTORMS TO FORM. DYNAMICS
LAG THE FRONT SOME...BUT STILL SOME CONCERN FOR STRONG WINDS
WITH ANY STORMS.
WINDY ON WED...AS COLDER AIR WORKS SOUTHWARD.
LOOKING AT DRY CONDITIONS AFT WED.
OUTLOOK...
TUE...VFR/MVFR WITH SCT SHOWERS AND TSTMS.
WED-FRI...VFR. NO SIG WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...ROSS
NEAR TERM...ROSS
SHORT TERM...ROSS
LONG TERM...ROSS
AVIATION...MARTIN/RXR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
214 PM MDT MON AUG 12 2013
.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 213 PM MDT MON AUG 12 2013
A LARGE SCALE BLOCKING PATTERN DOMINATES OVER NORTH
AMERICA WITH UPPER LEVEL TROUGHING OVER THE EASTERN HALF OF THE
CONTINENT AND A RIDGE ALONG THE CONTDVD. THE DAKOTAS REMAIN ON THE
COOL SIDE OF THE FRONT WHICH EXTENDS FROM CENTRAL MONTANA
SOUTHEASTWARD INTO THE CENTRAL PLAINS. SATELLITE IMAGERY SHOWS A
FAIRLY STRONG BUT DRY SHORT WAVE ROTATING SOUTHWARD INTO THE
NORTHERN PLAINS FROM CANADA THIS AFTERNOON. A WEAKER SYSTEM IS
FAINTLY VISIBLE IN THE WATER VAPOR LOOP MOVING SOUTHEASTWARD THROUGH
THE WESTERN DAKOTAS. AT THE SURFACE...RIDGING OVER THE EASTERN
DAKOTAS SET UP A RETURN FLOW OVER WESTERN SOUTH DAKOTA RESULTING IN
A BAND OF HIGHER DEQPOINTS EXTENDING INTO NORTHWEST SOUTH DAKOTA.
PLENTY OF INSTABILITY APPEARS TO BE AVAILABLE WITH SBCAPES IN EXCESS
OF 2000 J/KG OVER MUCH OF THE WEST...HOWEVER 0-6KM SHEAR WAS LESS
THAN 40 KTS OVER THE MOST OF WESTERN SOUTH DAKOTA. LITTLE OR NO
DEVELOPMENT HAD OCCURRED EAST OF THE HIGH TERRAIN OF CENTRAL/EASTERN
WYOMING AS OF 19Z.
TONIGHT...CHANCE POPS WILL REMAIN IN THE FORECAST FOR TONIGHT DUE TO
PLENTY OF INSTABILITY AND POSSIBLE WEAK UPPER LEVEL SUPPORT. AS WEAK
DISTURBANCES ALOFT CROSSES THE REGION TONIGHT AND THE LOW LEVEL JET
INTENSIFIES OVER THE AREA THIS EVENING...THE COVERAGE OF STORMS
COULD EXPAND SOME INTO THE OVERNIGHT HOURS...ESPECIALLY EAST OF THE
BLACK HILLS. STORM MOTION THIS EVENING SHOULD BE VERY SLOW...SO IF
SIGNIFICANT CONVECTION DOES DEVELOP LOCALLY HEAVY RAINFALL
ACCUMULATIONS ARE A POSSIBILITY.
TUESDAY AND TUESDAY NIGHT...THE MODELS CALL FOR THE RIDGE TO REMAIN
OVER THE EEASTERN DAKOTAS AND LEE SIDE TROUGHING TO REMAIN OVER
EASTERN WYOMING. THEREFORE DAILY CHANCES FOR SHOWERS AND STORMS WILL
STAY IN THE FORECAST FOR THE NEXT SEVERAL DAYS. THUNDERSTORMS WHICH
DEVELOP LATE TONIGHT COULD PERSIST WELL INTO THE DAYTIME HOURS
TUESDAY SUPPORTED BY CONTINUED INSTABILITY AND SEVERAL ADDITIONAL
WEAK UPPER LEVEL IMPULSES CROSSING THE FORECAST AREA. ISOLATED
STRONG TO SEVERE STORMS ARE AGAIN POSSIBLE...MAINLY FOR THE
AFTERNOON AND EVENING HOURS.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 213 PM MDT MON AUG 12 2013
MEAN WESTERN NOAM RIDGING TO REMAIN IN THE
PERIOD...WITH DOWNSTREAM MEAN NEGATIVE HEIGHT ANOMALIES LINGERING IN
EASTERN NOAM. ALTHOUGH A BRIEF REMOVAL OF THE PERSISTENT EASTERN
NOAM UPPER TROUGH WILL SUPPORT A BRIEF PERIOD OF LOCAL PROGRESSIVE
FLOW. NE PAC MEAN TROUGHING WILL CONTINUE TO SUPPORT SUBTLE IMPULSES
IN THE FLOW...WITH A MORE SUBSTANTIAL WAVE POSSIBLE TOWARD THE END
OF THIS WEEKEND. BEFOREHAND...A LINGERING STALLED BAROCLINIC ZONE
WILL PROVIDE A PATHWAY FOR PERTURBED WNW FLOW THROUGH MID WEEK. THE
NE PAC PERSISTENT UPPER TROUGH IS FORECAST TO CYCLE IN ALL
DETERMINISTIC MODELS...WITH UPPER RIDGING EXPECTED OVER THE NORTHERN
PLAINS FRIDAY THROUGH MUCH OF THE WEEKEND. THERE IS UNCERTAINTY IN
THE STRENGTH/PATH/AND LOCAL EFFECT OF THE EXPECTED EJECTING UPPER
TROUGH...WITH MODELS TRENDING FARTHER NORTH AND SHEARING THIS WAVE AS
IT PROGRESSES EAST...MOST PRONOUNCED IN THE ECMWF. THIS WOULD
EFFECTIVELY SHIFT THE REGION INTO ACTIVE SW FLOW WITH GENERALLY FAST
FLOW ON THE EDGE OF THE NORTHERN FA...SUPPORTING CONVECTIVE CHANCES
GIVEN A DEEP MOISTURE AXIS OVER THE REGION. FAIRLY WARM TEMPS WOULD
BE EXPECTED AS THE UPPER RIDGE TILTS OVER THE REGION...DIFFERENT
FROM PREVIOUS RUNS WHICH SUPPORTED A WESTERN BIAS TO THE WESTERN
CONUS RIDGE GIVEN A STRONGER EASTERN NOAM NEGATIVE HEIGHT ANOMALY.
HENCE...WILL SIDE WITH THE MIDDLE TO WARMER SIDE OF GUIDANCE FOR NOW
IN THE LATER PERIODS...WITH LOW CHANCES FOR PRECIP AT THE END OF THE
PERIOD GIVEN THE PROGGED ACTIVE FLOW REGIME...REMAINING COOLER ON
THE FRONT END OF THE PERIOD ALSO WITH LINGERING PRECIP CHANCES FOR
PERTURBED NW FLOW.
&&
.AVIATION...FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON
ISSUED AT 213 PM MDT MON AUG 12 2013
VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE PERIOD
SAVE IN AN NEAR SCT TS THIS AFTERNOON AND TONIGHT. MVFR/IFR CIGS
WILL BE POSSIBLE ONCE AGAIN TOWARD DAWN OVER THE EASTERN FA...WITH
EASTERLY FLOW POSSIBLY PUSHING STRATUS BACK INTO THE EASTERN BH
FOOTHILLS TUE MORNING. DID HINT AT THIS IN THE RAP TAF.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...CARPENTER
LONG TERM...JC
AVIATION...JC
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1141 AM MDT MON AUG 12 2013
.SHORT TERM...TODAY THROUGH TUESDAY NIGHT
ISSUED AT 308 AM MDT MON AUG 12 2013
CURRENT SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY STRETCHING FROM
CENTRAL MT TO SOUTHEASTERN WY AND THEN EASTWARD ACROSS NEB.
WEAKENING HIGH PRESSURE REMAINS OVER SOUTH CENTRAL CANADA. UPPER
LEVEL ANALYSIS CONTINUES TO SHOW HAS LARGE SCALE TROF OVER THE
GREAT LAKES AND NORTHEASTERN CONUS...WITH AN UPPER LOW ALONG THE
PACIFIC NW COAST. NEGATIVELY TILTED RIDGE REMAINS ACROSS THE
ROCKIES INTO THE SOUTHERN PLAINS. WEAK WEST TO NORTHWEST FLOW
ALOFT IS IN PLACE OVER THE NORTHERN PLAINS. EARLIER SHOWERS OVER
PORTIONS OF THE AREA HAVE DISSIPATED. SKIES ARE VARIABLY
CLOUDY...WITH PATCHY AREAS OF LOW CLOUDS TOWARD CENTRAL SD. TEMPS
ARE IN THE MID 50S TO MID 60S WITH LIGHT WINDS IN MOST AREAS.
DAILY CHANCES FOR SHOWERS AND STORMS WILL CONTINUE FOR THE NEXT
SEVERAL DAYS...WITH THE BEST CHANCES IN THE NEAR TERM LOOKING TO BE
FROM TONIGHT THROUGH TUESDAY EVENING. TEMPERATURES WILL REMAIN
SLIGHTLY BELOW AVERAGE THROUGH THE MIDDLE OF THE WEEK IN MOST
AREAS...WITH HIGHS IN THE 70S TO MID 80S.
FOR TODAY...DRY CONDITIONS ARE EXPECTED THROUGH THE MORNING
HOURS...WITH SOME SUNSHINE. CHANCE FOR STORMS WILL INCREASE THROUGH
THE AFTERNOON AND INTO TONIGHT AS ATMOSPHERE DESTABILIZES AND WEAK
ENERGY ALOFT APPROACHES BY THE EVENING. THE BLACK HILLS AND
NORTHEASTERN WY WILL GENERALLY SEE THE EARLIEST CHANCES FOR STORMS
THIS AFTERNOON AS FRONTAL BOUNDARY TRIES TO DRIFT EAST INTO
NORTHEASTERN WY AGAIN. ANOTHER AREA THAT COULD SEE A FEW
THUNDERSTORMS EARLIER IN THE AFTERNOON IS TOWARD CENTRAL SD...WHERE
SOME HI RES MODELS ARE SHOWING ACTIVITY DEVELOPING BY MID AFTERNOON.
WEAK LOW LEVEL UPSLOPE FLOW WILL PERSIST OVER MUCH OF THE
AREA...WITH PLENTY OF MOISTURE AND INSTABILITY PROGGED FOR THE BLACK
HILLS AREA EASTWARD THIS AFTERNOON. STEEPER MID LEVEL LAPSE RATES
ARE ALSO PROGGED LATER TODAY...HELPING TO WEAKEN THE CAP. SHEAR
WILL BE SLOWLY INCREASING THROUGH THE AFTERNOON AND INTO TONIGHT AND
SHOULD BE SUFFICIENT FOR A SUPERCELL OR TWO TO POTENTIALLY DEVELOP.
UPPER LEVEL SUPPORT LOOKS RATHER MINIMAL THROUGH THE AFTERNOON...SO
THIS WILL LIKELY KEEP ACTIVITY ISOLATED TO WIDELY SCATTERED THROUGH
THE AFTERNOON AND INTO THE EARLY EVENING IN MOST AREAS. A FEW STRONG
TO SEVERE STORMS ARE POSSIBLE LATER THIS AFTERNOON AND TONIGHT.
LARGE HAIL AND STRONG WIND GUSTS WILL BE THE MAIN THREATS WITH ANY
SEVERE STORMS. AS WEAK ENERGY ALOFT CROSSES TONIGHT AND LOW LEVEL
JET INTENSIFIES OVER THE AREA THIS EVENING...THE COVERAGE OF STORMS
COULD EXPAND SOME INTO THE OVERNIGHT HOURS...ESPECIALLY EAST OF THE
BLACK HILLS.
TUESDAY LOOKS TO BE A SIMILAR SETUP AGAIN...THOUGH CHANCES FOR
STORMS LOOK TO PERSIST ALL DAY AND INTO TUESDAY NIGHT. ACTIVITY
COULD BE A BIT MORE WIDESPREAD AND CONCENTRATED MORE TO THE BLACK
HILLS AND THE PLAINS TO THE SOUTH AND EAST. ISOLATED STRONG TO
SEVERE STORMS AGAIN LOOK LIKELY...MAINLY FOR THE AFTERNOON AND
EVENING HOURS.
&&
.LONG TERM...WEDNESDAY THROUGH SUNDAY
ISSUED AT 308 AM MDT MON AUG 12 2013
A GRADUAL CHANGE IN THE PATTERN IS EXPECTED THIS WEDNESDAY
THROUGH SATURDAY. ON WEDNESDAY THERE WILL BE YET ANOTHER SHORT-
WAVE TROUGH TRAVERSING THE RIDGE OVER THE CNTRL ROCKIES...AND THIS
SHOULD BRING A ROUND OF SHRA/TSRA TO THE CWA. THE FINAL SHORT-
WAVE TROUGH SHOULD MOVE SOUTHEAST THROUGH THE CWA ON THURSDAY.
THIS WILL BE FOLLOWED BY A SLOW EASTWARD PROGRESSION OF THE
RIDGE...BUT ALSO BUILDING UPPER HEIGHTS. THE NET RESULT SHOULD BE
A RELATIVE DRYING AND WARMING TREND OVER THE CURRENT/RECENT
PERSISTENT COOL AND MOIST PATTERN. NEVERTHELESS...TEMPS SHOULD BE
TEMPERED SOMEWHAT BY THE MOIST/GREEN GROUND AND THUS MAX TEMPS
HAVE BEEN TRIMMED BY 2-5 DEGREES. BY NEXT SUNDAY IT APPEARS A
SHORT-WAVE TROUGH WILL BREAK DOWN THE RIDGE AND MOVE ACROSS THE
NRN PLAINS. THIS COULD PRODUCE A FEW SEVERE STORMS...BUT IT ALSO
MAY RESULT IN A CRITICAL FIRE WEATHER PATTERN. HOWEVER...THE
RELATIVELY MOIST FUELS LIKELY WILL TEMPER THE EFFECTS OF THIS
PATTERN. THE RIDGE IS THEN PROGGED TO REBOUND ON MONDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1135 AM MDT MON AUG 12 2013
IFR/LIFR CIGS/VSBYS OVER PORTIONS OF WCNTRL SD /INCLUDING KRAP/
ARE BEGINNING TO ERODE AS FILTERED SUN WORKS ON THE BL. DID
RETAIN A LINGERING LIFR MENTION THERE INTO THE EARLY AFTERNOON.
OTHERWISE...VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE PERIOD
SAVE IN AN NEAR SCT TS THIS AFTERNOON AND TONIGHT. MVFR/IFR CIGS
WILL BE POSSIBLE ONCE AGAIN TOWARD DAWN OVER THE EASTERN FA...WITH
EASTERLY FLOW POSSIBLY PUSHING STRATUS BACK INTO THE EASTERN BH
FOOTHILLS TUE MORNING. DID HINT AT THIS IN THE RAP TAF.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...26
LONG TERM...BUNKERS
AVIATION...JC
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
346 PM CDT MON AUG 12 2013
.SHORT TERM...
WEATHER PATTERN OVER THE NEXT DAY WILL BE LARGELY DRIVEN BY
ELONGATED UPPER HIGH ALONG THE GULF COAST WITH A RIDGE EXTENDING
FROM AROUND THESE PARTS UP TO THE CANADIAN PRAIRIES. MONSOON
MOISTURE CONTINUES TO WRAP AROUND THE PERIPHERY OF THE HIGH CENTER
GENERALLY STREAMING FROM NORTHEASTERN NEW MEXICO TO THE TEXAS
PANHANDLE AND BEYOND. AREA OF SYNOPTIC SCALE LIFT IS EVIDENT TO OUR
NORTH AND NORTHWEST AND THIS IS WHERE TSTM ACTIVITY INITIATED.
HOWEVER...TO THE SOUTH...ACROSS OUR REGION...AXIS OF THETA-E MAXIMA
HAS HELPED INITIATE ISOLATED CONVECTION FROM DORA TO MEMPHIS. GIVEN
THAT THESE SHOWERS DEVELOPED BY 2PM...INDICATIONS ARE THAT THE
ATMOSPHERE IS SUFFICIENTLY MOIST TO SUPPORT AT LEAST SCATTERED STORMS
FOR MUCH OF THE AFTERNOON INTO THE EVENING HOURS...FAVORING THE
NORTHERN HALF OF THE AREA. AN INTERESTING SOLUTION IS EVIDENT IN
THE HRRR WITH CONVECTION FORMING OUT NORTHWEST OF LUBBOCK AND MOVING
SLOWLY THIS WAY...BUT PERHAPS NOT REACHING THE CITY. GIVEN THAT
THIS SOLUTION IS SOMEWHAT REPRESENTED IN LOCATION / THOUGH NOT
COVERAGE / HAVE EXPANDED POPS SOUTHWARD THIS EVENING. LIKE THE PAST
SEVERAL NIGHTS...LOW-END SEVERE STORMS WILL BE POSSIBLE WITH
CONDITIONS WANING TUESDAY MORNING FOR A WHILE. A BACK DOOR FRONT
IS INDICATED BY GUIDANCE AND WITH THE ALREADY PLENTIFUL CONVECTION
ACROSS THE PANHANDLE...PREFER THE QUICKER SOLUTION AND AS SUCH
HAVE BROUGHT THE BOUNDARY...AND ASSOCIATED INCREASED RAIN
CHANCES...INTO OUR CWFA DURING THE AFTERNOON ON TUESDAY.
&&
.LONG TERM...
MID-LEVEL PATTERN WILL CONTINUE TO AMPLIFY INTO THE EXTENDED WITH
STRONGER NW FLOW AND DEEP LAYER SHEAR ACROSS THE SOUTH PLAINS TUE
PM INTO WED IN THE WAKE OF THE FRONTAL BOUNDARY. THIS SCENARIO
SHOULD SUPPORT CONTINUED WIDESPREAD PRECIP CHANCES AS MOST MODELS
SUPPORT SOME Q-G LIFT ALONG WITH FRONTOGENETICAL FORCING CENTERED
OVER ERN NM INTO THE WRN SOUTH PLAINS. FAVORABLE 700MB THETA-E AXIS ALSO
REMAINS IN PLACE WITH PWATS INCREASING THROUGH THE FIRST COUPLE OF
DAYS OF THE EXTENDED PERIOD AS WELL. ONE LIMITING FACTOR FOR
CONSIDERATION FOR INCREASED COVERAGE WITH TIME IS THE INSTABILITY
DURING THE DAY WED. EXPECT CONSIDERABLE CLOUDINESS AND UPSLOPE
FLOW TO INHIBIT WARMING AND SUBSTANTIAL CAPE HOWEVER DEEPLY MOIST
ATMOSPHERE SHOULD AID DEVELOPMENT LOCALLY. ADDITIONAL HEATING
ACROSS EASTERN NM COUPLED WITH AMPLE SHEAR SHOULD HELP SOME
ACTIVITY TO ORGANIZE AND MOVE ACROSS THE WESTERN HALF OF THE AREA
AGAIN LATE EVENING AND OVERNIGHT WED NIGHT. SUBTLE SHORTWV
ACTIVITY TRAVERSING THE NW FLOW WILL HELP SUSTAIN AFTN STORMS THU
IN CONTINUED LIGHT UPSLOPE FLOW. ONCE AGAIN UNCAPPED ATMOSPHERE WILL
ALLOW SHOWERS TO FORM EARLY AND PREVENT THINGS FROM BECOMING TOO
UNSTABLE WITH SEVERE THREAT LIMITED OUTSIDE OF SOME HEAVY RAINERS.
FLOW TURNS MORE NRLY ON FRI AS RIDGE BUILDS FROM 4 CORNERS INTO
MONTANA. GFS AND EURO BOTH SUPPORT UPPER LOW DROPPING INTO THE MO
VALLEY ON SAT TO MAINTAIN SOME LIFT WITHIN REMNANT MOIST AXIS ON
EASTERN SIDE OF THE RIDGE. WITH CONTINUED ISOLD-SCT CONVECTION
POSSIBLE HAVE KEPT POPS GOING INTO THE WEEKEND WITH LITTLE TO NO
OVERALL WARMING TREND.
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 64 89 65 81 61 / 30 30 50 50 40
TULIA 65 89 67 80 62 / 30 30 50 50 40
PLAINVIEW 66 91 68 80 63 / 30 30 40 50 40
LEVELLAND 70 94 68 84 65 / 20 20 30 50 40
LUBBOCK 70 93 69 83 65 / 20 20 30 50 40
DENVER CITY 72 92 65 88 66 / 10 10 20 40 40
BROWNFIELD 73 94 70 86 66 / 10 10 20 50 40
CHILDRESS 72 96 69 84 67 / 30 40 50 50 30
SPUR 75 97 74 86 68 / 20 20 30 50 40
ASPERMONT 76 99 75 89 69 / 20 20 30 50 30
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
26/24
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
1229 PM CDT MON AUG 12 2013
.AVIATION...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT THE METROPLEX AND WACO
TAF SITES THROUGH 00Z WEDNESDAY. ISOLATED THUNDERSTORMS ARE
EXPECTED LATE AFTERNOON INTO THIS EVENING /21Z-03Z/ NORTH OF THE
DALLAS FORT WORTH METROPLEX AS AN UPEPR LEVEL DISTURBANCE SLIDES
ACROSS OKLAHOMA. ISOLATED SHOWERS AND THUNDERSTORMS ARE ALSO
POSSIBLE LATE AFTERNOON THROUGH EARLY EVENING /21Z-01Z/ SOUTH OF
WACO. ALTHOUGH IT IS NOT MENTIONED IN THE DFW TAF AT THIS
TIME...THERE MAY BE SOME ISOLATED THUNDERSTORMS NORTH OF I-20
AFTER 20Z TUESDAY.
58
&&
.UPDATE...
THE NAM12 HAS DONE A GOOD JOB WITH THE CURRENT ACTIVITY OVER NE
OKLAHOMA THIS MORNING ASSOCIATED WITH AN EAST-SOUTHEASTWARD MOVING
SHORTWAVE. THIS MODEL ALONG WITH RECENT RUNS OF THE HRRR HAVE
ADVERTISED ISOLATED THUNDERSTORM DEVELOPMENT FARTHER SOUTHWEST THIS
AFTERNOON INTO NORTHERN PORTIONS OF THE CWA. WILL GO AHEAD AND ADD
ISOLATED TS TO THE COUNTIES NORTH OF THE DALLAS-FORT WORTH
METROPLEX FOR THE AFTERNOON WITH TIMING MOST LIKELY AFTER 4
PM...WHILE CONTINUING WITH ISOLATED TS OVER THE FAR SOUTHERN
COUNTIES AS WELL. OTHERWISE THE FORECAST REMAINS IN GOOD SHAPE
WITH MOST AREAS REACHING UPPER 90S TO NEAR 100 DEGREE HIGH TEMPS
AGAIN TODAY.
30
&&
.PREV DISCUSSION... /ISSUED 424 AM CDT MON AUG 12 2013/
REGIONAL RADARS WERE SHOWING A FEW CLUSTERS OF SHOWERS AND
THUNDERSTORMS MOVING EAST-NORTHEAST FROM APPROXIMATELY PLAINVIEW
TX TO LAWTON OK. THIS AREA OF PRECIPITATION WAS MASKING THE
POSITION OF THE NORTHWARD MOVING BOUNDARY THAT WAS IN PLACE OVER
THE DFW METROPLEX YESTERDAY AFTERNOON. IT IS POSSIBLE THAT THE
BOUNDARY IS NEAR THE LINE OF SHOWER AND THUNDERSTORM ACTIVITY
MENTIONED ABOVE...BUT A CHAOTIC WIND AND TEMPERATURE FIELD DUE TO
MULTIPLE OUTFLOW BOUNDARIES MADE THE FRONT DIFFICULT TO LOCATE ON
A SURFACE SUBJECTIVE ANALYSIS AT 08Z. EARLY MORNING WATER VAPOR
SATELLITE IMAGERY SHOWED AN ANTICYCLONIC CIRCULATION CENTERED
NEAR EL PASO WITH WESTERLY FLOW ALOFT OVER KS AND OKLAHOMA.
FURTHER NORTH...A STRONG SHORTWAVE TROUGH WAS EVIDENT NORTH OF
MINNESOTA...MOVING SOUTHEAST TOWARDS THE UPPER GREAT LAKES REGION.
TODAY THROUGH TUESDAY...ASSUMING THE FRONT CONTINUES TO MOVE NORTH
THIS MORNING...THERE WILL BE NO OBVIOUS FOCUS FOR AFTERNOON
THUNDERSTORMS TODAY THROUGH EARLY TUESDAY AFTERNOON ACROSS NORTH
TX. IN GENERAL WITH PERSISTENT SOUTHERLY FLOW AND MOSTLY SUNNY
SKIES...WE SHOULD SEE HIGHS CONTINUE TO TOP OUT IN THE UPPER 90S
TO JUST ABOVE 100 DEGREES FOR MOST LOCATIONS MONDAY AND TUESDAY.
THERE IS SOME CONCERN THAT THE CLUSTER OF STORMS LOCATED FROM
PLAINVIEW TO LAWTON WILL BE ABLE TO SEND SOME SORT OF CONSOLIDATED
OUTFLOW BOUNDARY SOUTH TOWARDS THE RED RIVER THIS MORNING. THE
RADAR PRESENTATION OF THIS CONVECTION AT 08Z DID NOT SEEM VIGOROUS
ENOUGH TO SEND A BOUNDARY SOUTH TO THE RED RIVER...HOWEVER A FEW
EARLY MORNING RUNS OF THE RAP AND THE NCEP 4 KM WRF SEEM TO BE
ADVERTISING THIS SCENARIO FOR THUNDERSTORM CONSIDERATIONS LATER
THIS AFTERNOON...EVEN THE 06Z NAM APPEARS TO BE INDICATING A
SUBTLE BOUNDARY NEAR THE RED RIVER. HOWEVER...THE CONSENSUS OF
MOST MODEL GUIDANCE SENDS THE FRONT NORTH TO THE KS/OK BORDER
TODAY...WELL REMOVED FROM NORTH TX. WITH LITTLE CONFIDENCE THAT A
SIGNIFICANT BOUNDARY WILL MOVE TO THE RED RIVER OR INTO NORTH TX
THIS MORNING...LEFT 10 POPS IN THE FORECAST WITHOUT ANY MENTION OF
THUNDERSTORMS THROUGH THIS AFTERNOON.
WITH MOST MODEL GUIDANCE BRINGING THE FRONT NORTH TO THE KS/OK
BORDER THIS AFTERNOON...THIS SHOULD SERVE AS A NICE FOCUS FOR
AFTERNOON THUNDERSTORM INITIATION. THE MINNESOTA UPPER LEVEL
TROUGH IS EXPECTED TO DIVE SOUTHEAST TODAY WHICH MARKS THE
BEGINNING OF A LARGE SCALE TROUGH THAT WILL BUILD OVER THE ENTIRE
EASTERN CONUS BY LATE THIS WEEK. THIS FIRST STRONG SHORTWAVE
TROUGH WILL TURN THE WESTERLIES ALOFT OVER KS/OK SLIGHTLY TO THE
SOUTH...RESULTING IN WEST-NORTHWEST FLOW ALOFT BY THIS EVENING.
WITH STRONGER DEEP LAYER SHEAR TO WORK WITH ALONG THE KS/OK
BORDER...AND STEERING FLOW ALOFT TILTING TO THE SOUTH THIS
EVENING...IT IS POSSIBLE FOR SOME ORGANIZED MCS TO PULL AWAY FROM
THE FRONT AND MOVE SOUTH TOWARDS THE RED RIVER BEFORE MIDNIGHT
TONIGHT. OVERALL THINK THAT THE CHANCES OF THIS ARE
SMALL...HOWEVER DID GO WITH A SMALL AREA OF 20 POPS JUST SOUTH OF
THE RED RIVER TO ACCOUNT FOR THIS SCENARIO. MOST MODEL GUIDANCE
INDICATES VIGOROUS CONVECTION ALONG THE KS/OK BORDER BY THIS
AFTERNOON...SO WE WILL HAVE TO WATCH THE EVOLUTION OF ANY MCS FOR
SOME POTENTIAL TO MOVE INTO NORTH TX THIS EVENING OR OVERNIGHT.
DURING THE DAY ON TUESDAY THE CONTINUED SOUTHEASTWARD PUSH OF THE
MINNESOTA UPPER TROUGH WILL HELP TILT THE FLOW ALOFT MORE TO THE
NORTHWEST OVER THE SOUTH PLAINS AS UPPER LEVEL RIDGING REORGANIZES
OVER THE SOUTHWESTERN CONUS. ANOTHER STRONG SHORTWAVE TROUGH IS
EXPECTED TO MOVE SOUTHEAST OVER THE WESTERN GREAT LAKES TUESDAY
AFTERNOON WHICH SHOULD HELP SEND THE KS/OK COLD FRONT SOUTH INTO
NORTH TX BY TUESDAY NIGHT. ALL MODELS SHOW NUMEROUS SHOWERS AND
THUNDERSTORMS ALONG THE FRONT TUESDAY AFTERNOON AND EVENING. THIS
WILL LIKELY CAUSE THE FRONT TO MOVE TO THE SOUTH FASTER...SO
GENERALLY FAVORED MODELS WITH A QUICKER FRONTAL PASSAGE IN THIS
FORECAST.
HAVE THUNDERSTORM CHANCES INCREASING FROM AROUND 20 PERCENT NEAR
THE RED RIVER TUESDAY AFTERNOON TO 50 TO 60 PERCENT NEAR THE RED
RIVER TUESDAY EVENING. HAVE POPS IN THE FORECAST TUESDAY NIGHT AS
FAR SOUTH AS WACO...HOWEVER CONFIDENCE IN THUNDERSTORMS DIMINISHES
FROM NORTH TO SOUTH ACROSS THE CWA. THUNDERSTORMS ARE MOST LIKELY
ALONG AND NORTH OF INTERSTATE 20 TUESDAY EVENING AND OVERNIGHT.
THERE IS SOME CHANCE THAT THESE STORMS WILL BE SEVERE AS THEY MOVE
INTO NORTH TX TUESDAY NIGHT...HOWEVER SEVERE WEATHER POTENTIAL IS
EXPECTED TO BE LIMITED BY THE STORMS MOVING INTO THE AREA AFTER
SUNSET.
ANY SEVERE STORMS WOULD LIKELY BE IN THE FORM OF A SMALL LINEAR
MCS AS DEEP LAYER BULK SHEAR IS FORECAST TO BE 30 TO 35 KTS ALONG
AND NORTH OF INTERSTATE 20. SHEAR WEAKENS TO THE SOUTH...AND
STORMS ARE NOT AS LIKELY TO MOVE SOUTH OF INTERSTATE 20 UNTIL LATE
TUESDAY EVENING...SO SEVERE WEATHER CHANCES TO THE SOUTH OF I-20
LOOK FAIRLY SMALL AT THIS TIME. DAMAGING WINDS WOULD BE THE MOST
LIKELY SEVERE WEATHER HAZARD...WITH CLOUD TO GROUND LIGHTNING AND
LOCALLY HEAVY RAINFALL POSSIBLE WITH ANY STORM.
NOCTURNAL CONVECTION USUALLY WEAKENS SUBSTANTIALLY NEAR DAWN IN
THE ABSENCE OF UPPER LEVEL SUPPORT. THINK THAT SHOWERS AND STORMS
ALONG THE FRONT WILL TEND TO WEAKEN EARLY WEDNESDAY MORNING
LEAVING SOME UNORGANIZED SHOWER AND THUNDERSTORM ACTIVITY NEAR THE
FRONT AS IT STALLS OUT WEDNESDAY MORNING. THE FRONT WILL MOST
LIKELY BE LOCATED JUST SOUTH OF INTERSTATE 20 AT THAT
TIME. ASSUMING THE FRONT STALLS OUT IN THIS LULL OF CONVECTIVE
ACTIVITY...THE STALLED OUT FRONT SHOULD SERVE AS A FOCUS FOR
THUNDERSTORM INITIATION WEDNESDAY AFTERNOON. WENT AHEAD AND PLACED
50 POPS ALONG THE EXPECTED POSITION OF THE FRONT...ROUGHLY IN
BETWEEN DFW AND WACO WITH LOWER POPS TO THE NORTH AND SOUTH DURING
THE DAY ON WEDNESDAY.
ADDITIONAL THUNDERSTORM ACTIVITY ALONG THE FRONT WEDNESDAY
AFTERNOON SHOULD SEND THE FRONT SOUTH OUT OF THE CWA BY WEDNESDAY
EVENING. AS A RESULT WENT AHEAD AND MOVED THE BEST POPS SOUTH FROM
WEDNESDAY AFTERNOON THROUGH THE OVERNIGHT HOURS. BY THURSDAY
MORNING...THE FRONT IS EXPECTED TO BE LOCATED JUST SOUTH OR
SOUTHWEST OF THE CWA.
THURSDAY...ASSUMING THE FRONT IS NOT IN THE CWA...CONFIDENCE IN
WHEN AND WHERE STORMS WILL DEVELOP ACROSS THE AREA IS SOMEWHAT
LOW. THE GFS CONTINUES TO INDICATE A SHORTWAVE TROUGH MOVING
TOWARDS THE CWA THURSDAY AFTERNOON OR EVENING WHICH COULD
CERTAINLY CAUSE ISOLATED STORMS TO DEVELOP WHEREVER THE GREATEST
LIFT OCCURS. KEPT POPS IN THE 20 TO 30 PERCENT RANGE AT THIS TIME
BECAUSE THE BEST MOISTURE AND INSTABILITY FOR STORMS IS EXPECTED
TO REMAIN SOUTH OF THE FRONT. WITH THE FRONTAL POSITION AT LEAST
SOMEWHAT DEPENDENT ON THE COVERAGE AND INTENSITY OF STORMS EACH
DAY...THIS FORECAST COULD CHANGE SIGNIFICANTLY DEPENDING ON WHERE
THE FRONT ACTUALLY IS AT THIS TIME. HOWEVER FOR NOW MOST GUIDANCE
KEEPS THE FRONT SOUTH OF THE CWA WHICH SHOULD DAMPEN THUNDERSTORM
CHANCES IN GENERAL.
RAIN COOLED AIR ON WEDNESDAY...AND COLD AIR ADVECTION BEHIND THE
COLD FRONT SHOULD KEEP TEMPERATURES BELOW NORMAL FROM WEDNESDAY
THROUGH THE END OF THE WEEK. THIS SHOULD PROVIDE SOME NICE RELIEF
FROM THE PREVIOUS TWO WEEKS OF 100 DEGREE HEAT. HIGHS WILL
GENERALLY BE HELD INTO THE MID TO UPPER 80S NORTH OF INTERSTATE 20
WITH HIGHS IN THE LOWER 90S TO THE SOUTH.
FRIDAY THROUGH MONDAY...THE GFS AND ECMWF BOTH INDICATE A STRONGER
SHORTWAVE TROUGH WILL BUILD OVER THE REGION BY FRIDAY BRINGING IN
AN UNUSUAL UPPER AIR PATTERN DOMINATED BY NORTHERLY FLOW ALOFT
OVER THE REGION THROUGH THE WEEKEND. IN GENERAL THIS PATTERN
FAVORS COOLER THAN NORMAL TEMPERATURES WITH LOW RAIN CHANCES DUE
TO DRIER CONTINENTAL AIR BEING ADVECTED INTO THE REGION. THE
FORECAST REFLECTS THESE GENERAL GUIDELINES. MAY HAVE TO INCLUDE
SOME POPS IN THE FORECAST AT A LATER DATE AS SMALLER SCALE
FEATURES BECOME BETTER RESOLVED...HOWEVER NO WIDESPREAD
PRECIPITATION IS EXPECTED AT THIS TIME. TEMPERATURES SHOULD RETURN
TO SEASONAL NORMALS BY MONDAY.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 100 80 99 78 90 / 10 10 10 30 50
WACO, TX 98 77 99 78 94 / 10 5 10 20 40
PARIS, TX 96 75 95 73 83 / 10 20 20 60 40
DENTON, TX 99 77 98 75 88 / 10 10 10 40 40
MCKINNEY, TX 99 78 99 76 87 / 10 10 20 40 50
DALLAS, TX 101 82 101 81 90 / 10 10 10 30 50
TERRELL, TX 100 78 99 77 89 / 10 10 10 30 50
CORSICANA, TX 100 78 100 78 94 / 10 10 10 20 50
TEMPLE, TX 96 74 98 75 94 / 10 10 10 10 30
MINERAL WELLS, TX 99 77 98 76 88 / 10 10 10 30 50
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1022 AM CDT MON AUG 12 2013
.UPDATE...
THE NAM12 HAS DONE A GOOD JOB WITH THE CURRENT ACTIVITY OVER NE
OKLAHOMA THIS MORNING ASSOCIATED WITH AN EAST-SOUTHEASTWARD MOVING
SHORTWAVE. THIS MODEL ALONG WITH RECENT RUNS OF THE HRRR HAVE
ADVERTISED ISOLATED THUNDERSTORM DEVELOPMENT FARTHER SOUTHWEST THIS
AFTERNOON INTO NORTHERN PORTIONS OF THE CWA. WILL GO AHEAD AND ADD
ISOLATED TS TO THE COUNTIES NORTH OF THE DALLAS-FORT WORTH
METROPLEX FOR THE AFTERNOON WITH TIMING MOST LIKELY AFTER 4
PM...WHILE CONTINUING WITH ISOLATED TS OVER THE FAR SOUTHERN
COUNTIES AS WELL. OTHERWISE THE FORECAST REMAINS IN GOOD SHAPE
WITH MOST AREAS REACHING UPPER 90S TO NEAR 100 DEGREE HIGH TEMPS
AGAIN TODAY.
30
&&
.AVIATION...
NO MAJOR CONCERNS THIS CYCLE. MOSTLY CLEAR SKIES EXPECTED WITH
SOUTHERLY FLOW OF 8-12 KTS EXPECTED NEXT 24-30 HOURS.
CONVECTION THIS AFTERNOON OR EVENING ACROSS TEXAS IS EXPECTED TO
BE WELL-REMOVED FROM THE TAF SITES. ONE FAVORED AREA WILL BE CLOSE
TO THE RED RIVER NEAR A STATIONARY FRONT...WITH A SECOND FAVORED AREA
IN SOUTHEAST TEXAS NEAR DEEPER MOISTURE. WILL THEREFORE NOT HAVE
ANY MENTION OF SHOWERS OR STORMS IN TAF.
09/GP
&&
.PREV DISCUSSION... /ISSUED 424 AM CDT MON AUG 12 2013/
REGIONAL RADARS WERE SHOWING A FEW CLUSTERS OF SHOWERS AND
THUNDERSTORMS MOVING EAST-NORTHEAST FROM APPROXIMATELY PLAINVIEW
TX TO LAWTON OK. THIS AREA OF PRECIPITATION WAS MASKING THE
POSITION OF THE NORTHWARD MOVING BOUNDARY THAT WAS IN PLACE OVER
THE DFW METROPLEX YESTERDAY AFTERNOON. IT IS POSSIBLE THAT THE
BOUNDARY IS NEAR THE LINE OF SHOWER AND THUNDERSTORM ACTIVITY
MENTIONED ABOVE...BUT A CHAOTIC WIND AND TEMPERATURE FIELD DUE TO
MULTIPLE OUTFLOW BOUNDARIES MADE THE FRONT DIFFICULT TO LOCATE ON
A SURFACE SUBJECTIVE ANALYSIS AT 08Z. EARLY MORNING WATER VAPOR
SATELLITE IMAGERY SHOWED AN ANTICYCLONIC CIRCULATION CENTERED
NEAR EL PASO WITH WESTERLY FLOW ALOFT OVER KS AND OKLAHOMA.
FURTHER NORTH...A STRONG SHORTWAVE TROUGH WAS EVIDENT NORTH OF
MINNESOTA...MOVING SOUTHEAST TOWARDS THE UPPER GREAT LAKES REGION.
TODAY THROUGH TUESDAY...ASSUMING THE FRONT CONTINUES TO MOVE NORTH
THIS MORNING...THERE WILL BE NO OBVIOUS FOCUS FOR AFTERNOON
THUNDERSTORMS TODAY THROUGH EARLY TUESDAY AFTERNOON ACROSS NORTH
TX. IN GENERAL WITH PERSISTENT SOUTHERLY FLOW AND MOSTLY SUNNY
SKIES...WE SHOULD SEE HIGHS CONTINUE TO TOP OUT IN THE UPPER 90S
TO JUST ABOVE 100 DEGREES FOR MOST LOCATIONS MONDAY AND TUESDAY.
THERE IS SOME CONCERN THAT THE CLUSTER OF STORMS LOCATED FROM
PLAINVIEW TO LAWTON WILL BE ABLE TO SEND SOME SORT OF CONSOLIDATED
OUTFLOW BOUNDARY SOUTH TOWARDS THE RED RIVER THIS MORNING. THE
RADAR PRESENTATION OF THIS CONVECTION AT 08Z DID NOT SEEM VIGOROUS
ENOUGH TO SEND A BOUNDARY SOUTH TO THE RED RIVER...HOWEVER A FEW
EARLY MORNING RUNS OF THE RAP AND THE NCEP 4 KM WRF SEEM TO BE
ADVERTISING THIS SCENARIO FOR THUNDERSTORM CONSIDERATIONS LATER
THIS AFTERNOON...EVEN THE 06Z NAM APPEARS TO BE INDICATING A
SUBTLE BOUNDARY NEAR THE RED RIVER. HOWEVER...THE CONSENSUS OF
MOST MODEL GUIDANCE SENDS THE FRONT NORTH TO THE KS/OK BORDER
TODAY...WELL REMOVED FROM NORTH TX. WITH LITTLE CONFIDENCE THAT A
SIGNIFICANT BOUNDARY WILL MOVE TO THE RED RIVER OR INTO NORTH TX
THIS MORNING...LEFT 10 POPS IN THE FORECAST WITHOUT ANY MENTION OF
THUNDERSTORMS THROUGH THIS AFTERNOON.
WITH MOST MODEL GUIDANCE BRINGING THE FRONT NORTH TO THE KS/OK
BORDER THIS AFTERNOON...THIS SHOULD SERVE AS A NICE FOCUS FOR
AFTERNOON THUNDERSTORM INITIATION. THE MINNESOTA UPPER LEVEL
TROUGH IS EXPECTED TO DIVE SOUTHEAST TODAY WHICH MARKS THE
BEGINNING OF A LARGE SCALE TROUGH THAT WILL BUILD OVER THE ENTIRE
EASTERN CONUS BY LATE THIS WEEK. THIS FIRST STRONG SHORTWAVE
TROUGH WILL TURN THE WESTERLIES ALOFT OVER KS/OK SLIGHTLY TO THE
SOUTH...RESULTING IN WEST-NORTHWEST FLOW ALOFT BY THIS EVENING.
WITH STRONGER DEEP LAYER SHEAR TO WORK WITH ALONG THE KS/OK
BORDER...AND STEERING FLOW ALOFT TILTING TO THE SOUTH THIS
EVENING...IT IS POSSIBLE FOR SOME ORGANIZED MCS TO PULL AWAY FROM
THE FRONT AND MOVE SOUTH TOWARDS THE RED RIVER BEFORE MIDNIGHT
TONIGHT. OVERALL THINK THAT THE CHANCES OF THIS ARE
SMALL...HOWEVER DID GO WITH A SMALL AREA OF 20 POPS JUST SOUTH OF
THE RED RIVER TO ACCOUNT FOR THIS SCENARIO. MOST MODEL GUIDANCE
INDICATES VIGOROUS CONVECTION ALONG THE KS/OK BORDER BY THIS
AFTERNOON...SO WE WILL HAVE TO WATCH THE EVOLUTION OF ANY MCS FOR
SOME POTENTIAL TO MOVE INTO NORTH TX THIS EVENING OR OVERNIGHT.
DURING THE DAY ON TUESDAY THE CONTINUED SOUTHEASTWARD PUSH OF THE
MINNESOTA UPPER TROUGH WILL HELP TILT THE FLOW ALOFT MORE TO THE
NORTHWEST OVER THE SOUTH PLAINS AS UPPER LEVEL RIDGING REORGANIZES
OVER THE SOUTHWESTERN CONUS. ANOTHER STRONG SHORTWAVE TROUGH IS
EXPECTED TO MOVE SOUTHEAST OVER THE WESTERN GREAT LAKES TUESDAY
AFTERNOON WHICH SHOULD HELP SEND THE KS/OK COLD FRONT SOUTH INTO
NORTH TX BY TUESDAY NIGHT. ALL MODELS SHOW NUMEROUS SHOWERS AND
THUNDERSTORMS ALONG THE FRONT TUESDAY AFTERNOON AND EVENING. THIS
WILL LIKELY CAUSE THE FRONT TO MOVE TO THE SOUTH FASTER...SO
GENERALLY FAVORED MODELS WITH A QUICKER FRONTAL PASSAGE IN THIS
FORECAST.
HAVE THUNDERSTORM CHANCES INCREASING FROM AROUND 20 PERCENT NEAR
THE RED RIVER TUESDAY AFTERNOON TO 50 TO 60 PERCENT NEAR THE RED
RIVER TUESDAY EVENING. HAVE POPS IN THE FORECAST TUESDAY NIGHT AS
FAR SOUTH AS WACO...HOWEVER CONFIDENCE IN THUNDERSTORMS DIMINISHES
FROM NORTH TO SOUTH ACROSS THE CWA. THUNDERSTORMS ARE MOST LIKELY
ALONG AND NORTH OF INTERSTATE 20 TUESDAY EVENING AND OVERNIGHT.
THERE IS SOME CHANCE THAT THESE STORMS WILL BE SEVERE AS THEY MOVE
INTO NORTH TX TUESDAY NIGHT...HOWEVER SEVERE WEATHER POTENTIAL IS
EXPECTED TO BE LIMITED BY THE STORMS MOVING INTO THE AREA AFTER
SUNSET.
ANY SEVERE STORMS WOULD LIKELY BE IN THE FORM OF A SMALL LINEAR
MCS AS DEEP LAYER BULK SHEAR IS FORECAST TO BE 30 TO 35 KTS ALONG
AND NORTH OF INTERSTATE 20. SHEAR WEAKENS TO THE SOUTH...AND
STORMS ARE NOT AS LIKELY TO MOVE SOUTH OF INTERSTATE 20 UNTIL LATE
TUESDAY EVENING...SO SEVERE WEATHER CHANCES TO THE SOUTH OF I-20
LOOK FAIRLY SMALL AT THIS TIME. DAMAGING WINDS WOULD BE THE MOST
LIKELY SEVERE WEATHER HAZARD...WITH CLOUD TO GROUND LIGHTNING AND
LOCALLY HEAVY RAINFALL POSSIBLE WITH ANY STORM.
NOCTURNAL CONVECTION USUALLY WEAKENS SUBSTANTIALLY NEAR DAWN IN
THE ABSENCE OF UPPER LEVEL SUPPORT. THINK THAT SHOWERS AND STORMS
ALONG THE FRONT WILL TEND TO WEAKEN EARLY WEDNESDAY MORNING
LEAVING SOME UNORGANIZED SHOWER AND THUNDERSTORM ACTIVITY NEAR THE
FRONT AS IT STALLS OUT WEDNESDAY MORNING. THE FRONT WILL MOST
LIKELY BE LOCATED JUST SOUTH OF INTERSTATE 20 AT THAT
TIME. ASSUMING THE FRONT STALLS OUT IN THIS LULL OF CONVECTIVE
ACTIVITY...THE STALLED OUT FRONT SHOULD SERVE AS A FOCUS FOR
THUNDERSTORM INITIATION WEDNESDAY AFTERNOON. WENT AHEAD AND PLACED
50 POPS ALONG THE EXPECTED POSITION OF THE FRONT...ROUGHLY IN
BETWEEN DFW AND WACO WITH LOWER POPS TO THE NORTH AND SOUTH DURING
THE DAY ON WEDNESDAY.
ADDITIONAL THUNDERSTORM ACTIVITY ALONG THE FRONT WEDNESDAY
AFTERNOON SHOULD SEND THE FRONT SOUTH OUT OF THE CWA BY WEDNESDAY
EVENING. AS A RESULT WENT AHEAD AND MOVED THE BEST POPS SOUTH FROM
WEDNESDAY AFTERNOON THROUGH THE OVERNIGHT HOURS. BY THURSDAY
MORNING...THE FRONT IS EXPECTED TO BE LOCATED JUST SOUTH OR
SOUTHWEST OF THE CWA.
THURSDAY...ASSUMING THE FRONT IS NOT IN THE CWA...CONFIDENCE IN
WHEN AND WHERE STORMS WILL DEVELOP ACROSS THE AREA IS SOMEWHAT
LOW. THE GFS CONTINUES TO INDICATE A SHORTWAVE TROUGH MOVING
TOWARDS THE CWA THURSDAY AFTERNOON OR EVENING WHICH COULD
CERTAINLY CAUSE ISOLATED STORMS TO DEVELOP WHEREVER THE GREATEST
LIFT OCCURS. KEPT POPS IN THE 20 TO 30 PERCENT RANGE AT THIS TIME
BECAUSE THE BEST MOISTURE AND INSTABILITY FOR STORMS IS EXPECTED
TO REMAIN SOUTH OF THE FRONT. WITH THE FRONTAL POSITION AT LEAST
SOMEWHAT DEPENDENT ON THE COVERAGE AND INTENSITY OF STORMS EACH
DAY...THIS FORECAST COULD CHANGE SIGNIFICANTLY DEPENDING ON WHERE
THE FRONT ACTUALLY IS AT THIS TIME. HOWEVER FOR NOW MOST GUIDANCE
KEEPS THE FRONT SOUTH OF THE CWA WHICH SHOULD DAMPEN THUNDERSTORM
CHANCES IN GENERAL.
RAIN COOLED AIR ON WEDNESDAY...AND COLD AIR ADVECTION BEHIND THE
COLD FRONT SHOULD KEEP TEMPERATURES BELOW NORMAL FROM WEDNESDAY
THROUGH THE END OF THE WEEK. THIS SHOULD PROVIDE SOME NICE RELIEF
FROM THE PREVIOUS TWO WEEKS OF 100 DEGREE HEAT. HIGHS WILL
GENERALLY BE HELD INTO THE MID TO UPPER 80S NORTH OF INTERSTATE 20
WITH HIGHS IN THE LOWER 90S TO THE SOUTH.
FRIDAY THROUGH MONDAY...THE GFS AND ECMWF BOTH INDICATE A STRONGER
SHORTWAVE TROUGH WILL BUILD OVER THE REGION BY FRIDAY BRINGING IN
AN UNUSUAL UPPER AIR PATTERN DOMINATED BY NORTHERLY FLOW ALOFT
OVER THE REGION THROUGH THE WEEKEND. IN GENERAL THIS PATTERN
FAVORS COOLER THAN NORMAL TEMPERATURES WITH LOW RAIN CHANCES DUE
TO DRIER CONTINENTAL AIR BEING ADVECTED INTO THE REGION. THE
FORECAST REFLECTS THESE GENERAL GUIDELINES. MAY HAVE TO INCLUDE
SOME POPS IN THE FORECAST AT A LATER DATE AS SMALLER SCALE
FEATURES BECOME BETTER RESOLVED...HOWEVER NO WIDESPREAD
PRECIPITATION IS EXPECTED AT THIS TIME. TEMPERATURES SHOULD RETURN
TO SEASONAL NORMALS BY MONDAY.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 100 80 99 78 90 / 10 10 10 30 50
WACO, TX 98 77 99 78 94 / 10 5 10 20 40
PARIS, TX 96 75 95 73 83 / 10 20 20 60 40
DENTON, TX 99 77 98 75 88 / 10 10 10 40 40
MCKINNEY, TX 99 78 99 76 87 / 10 10 20 40 50
DALLAS, TX 101 82 101 81 90 / 10 10 10 30 50
TERRELL, TX 100 78 99 77 89 / 10 10 10 30 50
CORSICANA, TX 100 78 100 78 94 / 10 10 10 20 50
TEMPLE, TX 96 74 98 75 94 / 10 10 10 10 30
MINERAL WELLS, TX 99 77 98 76 88 / 10 10 10 30 50
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
58/30
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
955 AM CDT MON AUG 12 2013
.UPDATE...
A TRANSITION DAY WITH LOW END MODERATE RAIN CHANCES. NORTHEASTERN-
CENTERED SURFACE HIGH...WITH THE WESTERN EXPANSION OF FLORIDA-BASED
MID-LEVEL RIDGING...WILL PROVIDE THE SUBSIDENCE TO INHIBIT MORE
WIDESPREAD RAINFALL (AS WAS EXPERIENCED YESTERDAY). A HIGHLY MOIST
AND UNSTABLE ENVIRONMENT STILL HAS THE POTENTIAL TO ALLOW SCATTERED
SHOWERS AND ISOLATED STORMS TO DEVELOP CLOSER TO THE COAST AND
TRACK NORTHEAST. AS EARLY AFTERNOON SURFACE TEMPERATURES ACHIEVE
THE LOWER TO MIDDLE 90S...AREAL COVERAGE SHOULD INCREASE A BIT
FURTHER INLAND OVER THE CENTRAL TO NORTHEASTERN FORECAST AREA. 31
&&
.PREV DISCUSSION... /ISSUED 612 AM CDT MON AUG 12 2013/
AVIATION...
UPPER LEVEL DISTURBANCE RESPONSIBLE FOR OUR CONVECTION THIS
WEEKEND IS MOVING OFF TO THE WEST OF OUR REGION. THIS WILL LEAD TO
LOWER COVERAGE OF SHRA/TSRA TODAY AND MORE SOUTHERLY LOW LEVEL
WINDS. WITH THE SHIFT IN WIND DIRECTION EXPECT ANY TSRA THAT DO
DEVELOP TO MOVE TO THE NORTH RATHER THAN NORTHWEST. 38
PREV DISCUSSION... /ISSUED 424 AM CDT MON AUG 12 2013/
DISCUSSION...
TROPICAL AIRMASS OVER SE TX HAS BEEN RESPONSIBLE FOR MAINLY SCT
SHOWERS AND THUNDERSTORMS. DAY TIME HEATING HAS INCREASED
INSTABILITY OVER NORTHERN PORTIONS OF SE TX RESULTING IN STRONG TO
ALMOST SEVERE STORMS WITH SMALL HAIL AND LOCALIZED HEAVY RAINFALL.
NOT AS OPTIMISTIC WITH RAIN CHANCES TODAY FOR A COUPLE OF REASONS.
FIRST 00Z 500MB ANALYSIS HAS UPPER LEVEL RIDGE AND HEIGHT RISES
OVER THE AREA. LOOKS LIKE TWO RIDGE CENTERS ARE TAKING SHAPE OVER
N TX AND BERMUDA RIDGE EDGING IN ACROSS FLORIDA. MODELS ARE
PRETTY CONSISTENT WITH KEEPING A FLAT RIDGE OVER MUCH OF TX AND N
GULF COAST. WATER VAPOR IMAGERY SHOWS UPPER LEVEL LOW NOW OVER
MEXICO SOUTH OF RIO GRANDE. THINK THIS WILL BE TOO FAR WAY AND TOO
WEAK TO IMPACT SE TX. GOES SOUNDER PRECIP WATER IMAGERY SHOWS
ABOUT 1.9-2 INCH PRECIP WATER OVER THE REGION BUT THE TREND HAS
BEEN THAT OF DRYING. LATEST HRRR AND 00Z WRF-ARW ALONG WITH
NAM/GFS REALLY ALL POINT TO BEST COVERAGE OF CONVECTION OVER E TX
AND SW LA. DECIDED TO KEEP AT LEAST SOME 30 POPS FOR EASTERN PARTS
OF THE FORECAST AREA BASED ON THESE TRENDS WITH 20 POPS ELSEWHERE.
IT WILL TAKE A WHILE TO REACH THE LOW 90S FOR CONVECTION TO START
TO REALLY INITIATE. COULD TAKE MORE HEATING IF MOISTURE CONTINUES
TO DECREASE. STILL WILL NEED TO WATCH FOR STRONG STORMS THAT
APPROACH SEVERE LEVELS ESPECIALLY WHERE THERE IS MAXIMUM HEATING
AND INSTABILITY. POTENTIAL STILL EXISTS FOR LOCALIZED HEAVY RAIN
WITH THE STRONGER STORMS.
TUE THROUGH THUR UPPER LEVEL RIDGE BUILDS OVER TX AND MOVES BACK
OVER S ROCKIES/GREAT BASIN BY THURSDAY. THIS RESULTS IN NW FLOW
ALOFT OVER THE REGION WITH A BROAD TROUGH OVER THE GREAT LAKES.
LOOKS LIKE BOTH THE GFS/ECMWF ARE TRYING TO DEEPEN THE TROUGH OVER
THE MISS RIVER VALLEY LATE FRI THROUGH SATURDAY. THE PATTERN
SUPPORTS A FRONTAL BOUNDARY PUSHING INTO SE TX LATE WED THROUGH
THUR. FRONT MAY PUSH TO THE COAST ON FRI BEFORE STALLING. FRONT
SHOULD BE A FOCUS FOR THUNDERSTORM ACTIVITY SO MAY HAVE A MORE WET
PATTERN DEVELOP FOR THE END OF THE WEEK. TIMING OF THE FRONT WILL
BE THE MAIN CHALLENGE WITH THE FORECAST. THINK A SLOWER FRONTAL
PUSH LIKE THE GFS MAY BE THE BEST SOLUTION RIGHT NOW. GIVEN THAT
UPPER LEVEL FLOW BECOMES MORE AMPLIFIED THUR/FRI...THINK FRONT
WILL TAKE ITS TIME GETTING INTO SE TX. FOR NOW WILL KEEP 20/3O
POPS FOR THE AREA MAINLY DUE TO UNCERTAINTY SURROUNDING THE TIMING
OF THE FRONT.
DRIER BOUNDARY LAYER AIR SHOULD REACH SE TX FRI INTO SAT SO THINK
RAIN CHANCES WILL DROP OFF FOR NEXT WEEKEND. UPPER LEVEL TROUGH
AXIS LOOKS TO PUSH BY ON SATURDAY PER GFS WHILE THE ECMWF HOLD THE
TROUGH MORE TO THE WEST OF THE GFS AND DOES NOT DISSIPATE THE
FRONT AS QUICKLY. MAY NEED TO HOLD ONTO SOME POPS FOR THE WEEKEND
BUT THINK DRIER BOUNDARY LAYER WILL LIMIT PRECIP. THE UPPER LEVEL
TROUGH DOES LIFT OFF TO THE NE LATE IN THE WEEKEND SO THINK A DRIER
FORECAST FOR PRECIP LOOKS REASONABLE.
LASTLY THE GFS IS TRYING TO DEVELOP A TROPICAL LOW PRESSURE IN
THE NW CARIB ON THUR AND MOVES IT INTO INTO THE GULF FRI/SAT.
GIVEN UPPER LEVEL PATTERN THAT DEVELOPS OVER THE N GULF FOR THE
WEEKEND...SHOULD ANYTHING DEVELOP TROPICALLY IT WILL BE IN A
HIGHLY SHEARED ENVIRONMENT. UPPER LEVEL TROUGH WILL ALSO LIKELY
TAKE THE SYSTEM WELL EAST OF THE AREA TOWARDS FL PANHANDLE ON
SUNDAY. THIS WILL BE SOMETHING TO KEEP AN EYE ON BUT OVERALL NOT
MUCH OF A CONCERN.
39
MARINE...
A FEW ISOLATED SHOWERS ACROSS THE COASTAL WATERS THIS MORNING BUT
COVERAGE WILL BE MUCH LESS TODAY THAN OVER THE WEEKEND. A
RELATIVELY FLAT PRESSURE GRADIENT ACROSS THE COASTAL WATERS WILL
KEEP LIGHT ONSHORE WINDS IN PLACE THROUGH THE MIDDLE OF THE WEEK.
A WEAK FRONT WILL APPROACH THE COAST LATE IN THE WEEK LEADING TO A
BRIEF PERIOD OF OFFSHORE WINDS. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 99 75 100 76 102 / 20 10 10 10 20
HOUSTON (IAH) 95 77 97 78 99 / 30 10 10 10 20
GALVESTON (GLS) 92 82 93 83 92 / 20 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...31
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
640 AM CDT MON AUG 12 2013
.AVIATION...
NO MAJOR CONCERNS THIS CYCLE. MOSTLY CLEAR SKIES EXPECTED WITH
SOUTHERLY FLOW OF 8-12 KTS EXPECTED NEXT 24-30 HOURS.
CONVECTION THIS AFTERNOON OR EVENING ACROSS TEXAS IS EXPECTED TO
BE WELL-REMOVED FROM THE TAF SITES. ONE FAVORED AREA WILL BE CLOSE
TO THE RED RIVER NEAR A STATIONARY FRONT...WITH A SECOND FAVORED AREA
IN SOUTHEAST TEXAS NEAR DEEPER MOISTURE. WILL THEREFORE NOT HAVE
ANY MENTION OF SHOWERS OR STORMS IN TAF.
09/GP
&&
.PREV DISCUSSION... /ISSUED 424 AM CDT MON AUG 12 2013/
REGIONAL RADARS WERE SHOWING A FEW CLUSTERS OF SHOWERS AND
THUNDERSTORMS MOVING EAST-NORTHEAST FROM APPROXIMATELY PLAINVIEW
TX TO LAWTON OK. THIS AREA OF PRECIPITATION WAS MASKING THE
POSITION OF THE NORTHWARD MOVING BOUNDARY THAT WAS IN PLACE OVER
THE DFW METROPLEX YESTERDAY AFTERNOON. IT IS POSSIBLE THAT THE
BOUNDARY IS NEAR THE LINE OF SHOWER AND THUNDERSTORM ACTIVITY
MENTIONED ABOVE...BUT A CHAOTIC WIND AND TEMPERATURE FIELD DUE TO
MULTIPLE OUTFLOW BOUNDARIES MADE THE FRONT DIFFICULT TO LOCATE ON
A SURFACE SUBJECTIVE ANALYSIS AT 08Z. EARLY MORNING WATER VAPOR
SATELLITE IMAGERY SHOWED AN ANTICYCLONIC CIRCULATION CENTERED
NEAR EL PASO WITH WESTERLY FLOW ALOFT OVER KS AND OKLAHOMA.
FURTHER NORTH...A STRONG SHORTWAVE TROUGH WAS EVIDENT NORTH OF
MINNESOTA...MOVING SOUTHEAST TOWARDS THE UPPER GREAT LAKES REGION.
TODAY THROUGH TUESDAY...ASSUMING THE FRONT CONTINUES TO MOVE NORTH
THIS MORNING...THERE WILL BE NO OBVIOUS FOCUS FOR AFTERNOON
THUNDERSTORMS TODAY THROUGH EARLY TUESDAY AFTERNOON ACROSS NORTH
TX. IN GENERAL WITH PERSISTENT SOUTHERLY FLOW AND MOSTLY SUNNY
SKIES...WE SHOULD SEE HIGHS CONTINUE TO TOP OUT IN THE UPPER 90S
TO JUST ABOVE 100 DEGREES FOR MOST LOCATIONS MONDAY AND TUESDAY.
THERE IS SOME CONCERN THAT THE CLUSTER OF STORMS LOCATED FROM
PLAINVIEW TO LAWTON WILL BE ABLE TO SEND SOME SORT OF CONSOLIDATED
OUTFLOW BOUNDARY SOUTH TOWARDS THE RED RIVER THIS MORNING. THE
RADAR PRESENTATION OF THIS CONVECTION AT 08Z DID NOT SEEM VIGOROUS
ENOUGH TO SEND A BOUNDARY SOUTH TO THE RED RIVER...HOWEVER A FEW
EARLY MORNING RUNS OF THE RAP AND THE NCEP 4 KM WRF SEEM TO BE
ADVERTISING THIS SCENARIO FOR THUNDERSTORM CONSIDERATIONS LATER
THIS AFTERNOON...EVEN THE 06Z NAM APPEARS TO BE INDICATING A
SUBTLE BOUNDARY NEAR THE RED RIVER. HOWEVER...THE CONSENSUS OF
MOST MODEL GUIDANCE SENDS THE FRONT NORTH TO THE KS/OK BORDER
TODAY...WELL REMOVED FROM NORTH TX. WITH LITTLE CONFIDENCE THAT A
SIGNIFICANT BOUNDARY WILL MOVE TO THE RED RIVER OR INTO NORTH TX
THIS MORNING...LEFT 10 POPS IN THE FORECAST WITHOUT ANY MENTION OF
THUNDERSTORMS THROUGH THIS AFTERNOON.
WITH MOST MODEL GUIDANCE BRINGING THE FRONT NORTH TO THE KS/OK
BORDER THIS AFTERNOON...THIS SHOULD SERVE AS A NICE FOCUS FOR
AFTERNOON THUNDERSTORM INITIATION. THE MINNESOTA UPPER LEVEL
TROUGH IS EXPECTED TO DIVE SOUTHEAST TODAY WHICH MARKS THE
BEGINNING OF A LARGE SCALE TROUGH THAT WILL BUILD OVER THE ENTIRE
EASTERN CONUS BY LATE THIS WEEK. THIS FIRST STRONG SHORTWAVE
TROUGH WILL TURN THE WESTERLIES ALOFT OVER KS/OK SLIGHTLY TO THE
SOUTH...RESULTING IN WEST-NORTHWEST FLOW ALOFT BY THIS EVENING.
WITH STRONGER DEEP LAYER SHEAR TO WORK WITH ALONG THE KS/OK
BORDER...AND STEERING FLOW ALOFT TILTING TO THE SOUTH THIS
EVENING...IT IS POSSIBLE FOR SOME ORGANIZED MCS TO PULL AWAY FROM
THE FRONT AND MOVE SOUTH TOWARDS THE RED RIVER BEFORE MIDNIGHT
TONIGHT. OVERALL THINK THAT THE CHANCES OF THIS ARE
SMALL...HOWEVER DID GO WITH A SMALL AREA OF 20 POPS JUST SOUTH OF
THE RED RIVER TO ACCOUNT FOR THIS SCENARIO. MOST MODEL GUIDANCE
INDICATES VIGOROUS CONVECTION ALONG THE KS/OK BORDER BY THIS
AFTERNOON...SO WE WILL HAVE TO WATCH THE EVOLUTION OF ANY MCS FOR
SOME POTENTIAL TO MOVE INTO NORTH TX THIS EVENING OR OVERNIGHT.
DURING THE DAY ON TUESDAY THE CONTINUED SOUTHEASTWARD PUSH OF THE
MINNESOTA UPPER TROUGH WILL HELP TILT THE FLOW ALOFT MORE TO THE
NORTHWEST OVER THE SOUTH PLAINS AS UPPER LEVEL RIDGING REORGANIZES
OVER THE SOUTHWESTERN CONUS. ANOTHER STRONG SHORTWAVE TROUGH IS
EXPECTED TO MOVE SOUTHEAST OVER THE WESTERN GREAT LAKES TUESDAY
AFTERNOON WHICH SHOULD HELP SEND THE KS/OK COLD FRONT SOUTH INTO
NORTH TX BY TUESDAY NIGHT. ALL MODELS SHOW NUMEROUS SHOWERS AND
THUNDERSTORMS ALONG THE FRONT TUESDAY AFTERNOON AND EVENING. THIS
WILL LIKELY CAUSE THE FRONT TO MOVE TO THE SOUTH FASTER...SO
GENERALLY FAVORED MODELS WITH A QUICKER FRONTAL PASSAGE IN THIS
FORECAST.
HAVE THUNDERSTORM CHANCES INCREASING FROM AROUND 20 PERCENT NEAR
THE RED RIVER TUESDAY AFTERNOON TO 50 TO 60 PERCENT NEAR THE RED
RIVER TUESDAY EVENING. HAVE POPS IN THE FORECAST TUESDAY NIGHT AS
FAR SOUTH AS WACO...HOWEVER CONFIDENCE IN THUNDERSTORMS DIMINISHES
FROM NORTH TO SOUTH ACROSS THE CWA. THUNDERSTORMS ARE MOST LIKELY
ALONG AND NORTH OF INTERSTATE 20 TUESDAY EVENING AND OVERNIGHT.
THERE IS SOME CHANCE THAT THESE STORMS WILL BE SEVERE AS THEY MOVE
INTO NORTH TX TUESDAY NIGHT...HOWEVER SEVERE WEATHER POTENTIAL IS
EXPECTED TO BE LIMITED BY THE STORMS MOVING INTO THE AREA AFTER
SUNSET.
ANY SEVERE STORMS WOULD LIKELY BE IN THE FORM OF A SMALL LINEAR
MCS AS DEEP LAYER BULK SHEAR IS FORECAST TO BE 30 TO 35 KTS ALONG
AND NORTH OF INTERSTATE 20. SHEAR WEAKENS TO THE SOUTH...AND
STORMS ARE NOT AS LIKELY TO MOVE SOUTH OF INTERSTATE 20 UNTIL LATE
TUESDAY EVENING...SO SEVERE WEATHER CHANCES TO THE SOUTH OF I-20
LOOK FAIRLY SMALL AT THIS TIME. DAMAGING WINDS WOULD BE THE MOST
LIKELY SEVERE WEATHER HAZARD...WITH CLOUD TO GROUND LIGHTNING AND
LOCALLY HEAVY RAINFALL POSSIBLE WITH ANY STORM.
NOCTURNAL CONVECTION USUALLY WEAKENS SUBSTANTIALLY NEAR DAWN IN
THE ABSENCE OF UPPER LEVEL SUPPORT. THINK THAT SHOWERS AND STORMS
ALONG THE FRONT WILL TEND TO WEAKEN EARLY WEDNESDAY MORNING
LEAVING SOME UNORGANIZED SHOWER AND THUNDERSTORM ACTIVITY NEAR THE
FRONT AS IT STALLS OUT WEDNESDAY MORNING. THE FRONT WILL MOST
LIKELY BE LOCATED JUST SOUTH OF INTERSTATE 20 AT THAT
TIME. ASSUMING THE FRONT STALLS OUT IN THIS LULL OF CONVECTIVE
ACTIVITY...THE STALLED OUT FRONT SHOULD SERVE AS A FOCUS FOR
THUNDERSTORM INITIATION WEDNESDAY AFTERNOON. WENT AHEAD AND PLACED
50 POPS ALONG THE EXPECTED POSITION OF THE FRONT...ROUGHLY IN
BETWEEN DFW AND WACO WITH LOWER POPS TO THE NORTH AND SOUTH DURING
THE DAY ON WEDNESDAY.
ADDITIONAL THUNDERSTORM ACTIVITY ALONG THE FRONT WEDNESDAY
AFTERNOON SHOULD SEND THE FRONT SOUTH OUT OF THE CWA BY WEDNESDAY
EVENING. AS A RESULT WENT AHEAD AND MOVED THE BEST POPS SOUTH FROM
WEDNESDAY AFTERNOON THROUGH THE OVERNIGHT HOURS. BY THURSDAY
MORNING...THE FRONT IS EXPECTED TO BE LOCATED JUST SOUTH OR
SOUTHWEST OF THE CWA.
THURSDAY...ASSUMING THE FRONT IS NOT IN THE CWA...CONFIDENCE IN
WHEN AND WHERE STORMS WILL DEVELOP ACROSS THE AREA IS SOMEWHAT
LOW. THE GFS CONTINUES TO INDICATE A SHORTWAVE TROUGH MOVING
TOWARDS THE CWA THURSDAY AFTERNOON OR EVENING WHICH COULD
CERTAINLY CAUSE ISOLATED STORMS TO DEVELOP WHEREVER THE GREATEST
LIFT OCCURS. KEPT POPS IN THE 20 TO 30 PERCENT RANGE AT THIS TIME
BECAUSE THE BEST MOISTURE AND INSTABILITY FOR STORMS IS EXPECTED
TO REMAIN SOUTH OF THE FRONT. WITH THE FRONTAL POSITION AT LEAST
SOMEWHAT DEPENDENT ON THE COVERAGE AND INTENSITY OF STORMS EACH
DAY...THIS FORECAST COULD CHANGE SIGNIFICANTLY DEPENDING ON WHERE
THE FRONT ACTUALLY IS AT THIS TIME. HOWEVER FOR NOW MOST GUIDANCE
KEEPS THE FRONT SOUTH OF THE CWA WHICH SHOULD DAMPEN THUNDERSTORM
CHANCES IN GENERAL.
RAIN COOLED AIR ON WEDNESDAY...AND COLD AIR ADVECTION BEHIND THE
COLD FRONT SHOULD KEEP TEMPERATURES BELOW NORMAL FROM WEDNESDAY
THROUGH THE END OF THE WEEK. THIS SHOULD PROVIDE SOME NICE RELIEF
FROM THE PREVIOUS TWO WEEKS OF 100 DEGREE HEAT. HIGHS WILL
GENERALLY BE HELD INTO THE MID TO UPPER 80S NORTH OF INTERSTATE 20
WITH HIGHS IN THE LOWER 90S TO THE SOUTH.
FRIDAY THROUGH MONDAY...THE GFS AND ECMWF BOTH INDICATE A STRONGER
SHORTWAVE TROUGH WILL BUILD OVER THE REGION BY FRIDAY BRINGING IN
AN UNUSUAL UPPER AIR PATTERN DOMINATED BY NORTHERLY FLOW ALOFT
OVER THE REGION THROUGH THE WEEKEND. IN GENERAL THIS PATTERN
FAVORS COOLER THAN NORMAL TEMPERATURES WITH LOW RAIN CHANCES DUE
TO DRIER CONTINENTAL AIR BEING ADVECTED INTO THE REGION. THE
FORECAST REFLECTS THESE GENERAL GUIDELINES. MAY HAVE TO INCLUDE
SOME POPS IN THE FORECAST AT A LATER DATE AS SMALLER SCALE
FEATURES BECOME BETTER RESOLVED...HOWEVER NO WIDESPREAD
PRECIPITATION IS EXPECTED AT THIS TIME. TEMPERATURES SHOULD RETURN
TO SEASONAL NORMALS BY MONDAY.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 100 80 99 78 90 / 10 10 10 30 50
WACO, TX 98 77 99 78 94 / 10 5 10 20 40
PARIS, TX 96 75 95 73 83 / 10 20 20 60 40
DENTON, TX 99 77 98 75 88 / 10 10 10 40 40
MCKINNEY, TX 99 78 99 76 87 / 10 10 20 40 50
DALLAS, TX 101 82 101 81 90 / 10 10 10 30 50
TERRELL, TX 100 78 99 77 89 / 10 10 10 30 50
CORSICANA, TX 100 78 100 78 94 / 10 10 10 20 50
TEMPLE, TX 96 74 98 75 94 / 10 10 10 10 30
MINERAL WELLS, TX 99 77 98 76 88 / 10 10 10 30 50
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
09/
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
612 AM CDT MON AUG 12 2013
.DISCUSSION...
SEE AVIATION FOR 12Z TAF DISCUSSION.
&&
.AVIATION...
UPPER LEVEL DISTURBANCE RESPONSIBLE FOR OUR CONVECTION THIS
WEEKEND IS MOVING OFF TO THE WEST OF OUR REGION. THIS WILL LEAD TO
LOWER COVERAGE OF SHRA/TSRA TODAY AND MORE SOUTHERLY LOW LEVEL
WINDS. WITH THE SHIFT IN WIND DIRECTION EXPECT ANY TSRA THAT DO
DEVELOP TO MOVE TO THE NORTH RATHER THAN NORTHWEST. 38
&&
.PREV DISCUSSION... /ISSUED 424 AM CDT MON AUG 12 2013/
DISCUSSION...
TROPICAL AIRMASS OVER SE TX HAS BEEN RESPONSIBLE FOR MAINLY SCT
SHOWERS AND THUNDERSTORMS. DAY TIME HEATING HAS INCREASED
INSTABILITY OVER NORTHERN PORTIONS OF SE TX RESULTING IN STRONG TO
ALMOST SEVERE STORMS WITH SMALL HAIL AND LOCALIZED HEAVY RAINFALL.
NOT AS OPTIMISTIC WITH RAIN CHANCES TODAY FOR A COUPLE OF REASONS.
FIRST 00Z 500MB ANALYSIS HAS UPPER LEVEL RIDGE AND HEIGHT RISES
OVER THE AREA. LOOKS LIKE TWO RIDGE CENTERS ARE TAKING SHAPE OVER
N TX AND BERMUDA RIDGE EDGING IN ACROSS FLORIDA. MODELS ARE
PRETTY CONSISTENT WITH KEEPING A FLAT RIDGE OVER MUCH OF TX AND N
GULF COAST. WATER VAPOR IMAGERY SHOWS UPPER LEVEL LOW NOW OVER
MEXICO SOUTH OF RIO GRANDE. THINK THIS WILL BE TOO FAR WAY AND TOO
WEAK TO IMPACT SE TX. GOES SOUNDER PRECIP WATER IMAGERY SHOWS
ABOUT 1.9-2 INCH PRECIP WATER OVER THE REGION BUT THE TREND HAS
BEEN THAT OF DRYING. LATEST HRRR AND 00Z WRF-ARW ALONG WITH
NAM/GFS REALLY ALL POINT TO BEST COVERAGE OF CONVECTION OVER E TX
AND SW LA. DECIDED TO KEEP AT LEAST SOME 30 POPS FOR EASTERN PARTS
OF THE FORECAST AREA BASED ON THESE TRENDS WITH 20 POPS ELSEWHERE.
IT WILL TAKE A WHILE TO REACH THE LOW 90S FOR CONVECTION TO START
TO REALLY INITIATE. COULD TAKE MORE HEATING IF MOISTURE CONTINUES
TO DECREASE. STILL WILL NEED TO WATCH FOR STRONG STORMS THAT
APPROACH SEVERE LEVELS ESPECIALLY WHERE THERE IS MAXIMUM HEATING
AND INSTABILITY. POTENTIAL STILL EXISTS FOR LOCALIZED HEAVY RAIN
WITH THE STRONGER STORMS.
TUE THROUGH THUR UPPER LEVEL RIDGE BUILDS OVER TX AND MOVES BACK
OVER S ROCKIES/GREAT BASIN BY THURSDAY. THIS RESULTS IN NW FLOW
ALOFT OVER THE REGION WITH A BROAD TROUGH OVER THE GREAT LAKES.
LOOKS LIKE BOTH THE GFS/ECMWF ARE TRYING TO DEEPEN THE TROUGH OVER
THE MISS RIVER VALLEY LATE FRI THROUGH SATURDAY. THE PATTERN
SUPPORTS A FRONTAL BOUNDARY PUSHING INTO SE TX LATE WED THROUGH
THUR. FRONT MAY PUSH TO THE COAST ON FRI BEFORE STALLING. FRONT
SHOULD BE A FOCUS FOR THUNDERSTORM ACTIVITY SO MAY HAVE A MORE WET
PATTERN DEVELOP FOR THE END OF THE WEEK. TIMING OF THE FRONT WILL
BE THE MAIN CHALLENGE WITH THE FORECAST. THINK A SLOWER FRONTAL
PUSH LIKE THE GFS MAY BE THE BEST SOLUTION RIGHT NOW. GIVEN THAT
UPPER LEVEL FLOW BECOMES MORE AMPLIFIED THUR/FRI...THINK FRONT
WILL TAKE ITS TIME GETTING INTO SE TX. FOR NOW WILL KEEP 20/3O
POPS FOR THE AREA MAINLY DUE TO UNCERTAINTY SURROUNDING THE TIMING
OF THE FRONT.
DRIER BOUNDARY LAYER AIR SHOULD REACH SE TX FRI INTO SAT SO THINK
RAIN CHANCES WILL DROP OFF FOR NEXT WEEKEND. UPPER LEVEL TROUGH
AXIS LOOKS TO PUSH BY ON SATURDAY PER GFS WHILE THE ECMWF HOLD THE
TROUGH MORE TO THE WEST OF THE GFS AND DOES NOT DISSIPATE THE
FRONT AS QUICKLY. MAY NEED TO HOLD ONTO SOME POPS FOR THE WEEKEND
BUT THINK DRIER BOUNDARY LAYER WILL LIMIT PRECIP. THE UPPER LEVEL
TROUGH DOES LIFT OFF TO THE NE LATE IN THE WEEKEND SO THINK A
DRIER FORECAST FOR PRECIP LOOKS REASONABLE.
LASTLY THE GFS IS TRYING TO DEVELOP A TROPICAL LOW PRESSURE IN
THE NW CARIB ON THUR AND MOVES IT INTO INTO THE GULF FRI/SAT.
GIVEN UPPER LEVEL PATTERN THAT DEVELOPS OVER THE N GULF FOR THE
WEEKEND...SHOULD ANYTHING DEVELOP TROPICALLY IT WILL BE IN A
HIGHLY SHEARED ENVIRONMENT. UPPER LEVEL TROUGH WILL ALSO LIKELY
TAKE THE SYSTEM WELL EAST OF THE AREA TOWARDS FL PANHANDLE ON
SUNDAY. THIS WILL BE SOMETHING TO KEEP AN EYE ON BUT OVERALL NOT
MUCH OF A CONCERN.
39
MARINE...
A FEW ISOLATED SHOWERS ACROSS THE COASTAL WATERS THIS MORNING BUT
COVERAGE WILL BE MUCH LESS TODAY THAN OVER THE WEEKEND. A
RELATIVELY FLAT PRESSURE GRADIENT ACROSS THE COASTAL WATERS WILL
KEEP LIGHT ONSHORE WINDS IN PLACE THROUGH THE MIDDLE OF THE WEEK.
A WEAK FRONT WILL APPROACH THE COAST LATE IN THE WEEK LEADING TO A
BRIEF PERIOD OF OFFSHORE WINDS. 38
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 99 77 99 77 99 / 20 10 10 10 20
HOUSTON (IAH) 95 77 97 77 96 / 30 10 10 10 20
GALVESTON (GLS) 92 81 93 81 92 / 30 10 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...99
AVIATION/MARINE...38