Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/07/13
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
851 PM MDT FRI SEP 6 2013
.UPDATE...
&&
.SHORT TERM...SCATTERED SHOWERS AND ISOLATED TS STORMS STILL ON
GOING OVER THE MOUNTAINS AND HIGH VALLEYS WITH SOUTHERLY STEERING
FLOW MOVING STORMS FROM SOUTH TO NORTH. THE WEAK ACTIVITY OVER THE
NORTHEAST PLAINS HAS DISSIPATED WHILE OUTFLOW BOUNDARY CONTINUES
TO PUSH SOUTHEAST INTO THE PALMER DIVIDE AND WASHINGTON COUNTY.
DON`T EXPECT ANY MORE SHOWERS OVER THE PLAINS WITH LACK OF ANY
ADDITIONAL BOUNDARY COLLISIONS. THE STORMS IN THE MOUNTAINS WILL
GRADUALLY DIMINISH AROUND MIDNIGHT WITH GRADUAL CLEARING SKIES.
.AVIATION...SURFACE WINDS HAVE SHIFTED TO NORTH TO NORTHEAST THIS
EVENING FOLLOWING EARLIER OUTFLOW BOUNDARY. EXPECT A CONTINUED
WEAKENING OF THE NORTHERLY WINDS AND THEN A SHIFT BACK TO DRAINAGE
WINDS TOWARDS MIDNIGHT. GRADUAL CLEARING OF THE MID LEVEL DECK
THROUGH THE NIGHT.
&&
.PREV DISCUSSION... /ISSUED 357 PM MDT FRI SEP 6 2013/
SHORT TERM...PRESENT FORECAST GRIDS NEED LITTLE WORK. ONGOING
CONVECTION SHOULD CONFINE ITSELF MOSTLY TO THE FOOTHILLS THIS
EVENING ALTHOUGH SEVERAL RECENT HRRR RUNS WANT TO BRING A BIT OF
IT SOUTHEAST ACROSS THE NORTHERN/CENTRAL PORTIONS OF THE URBAN
CORRIDOR TOWARDS 00Z.
SATURDAY SHOULD BE CLOSE TO A CARBON COPY OF TODAY AS THE UPPER
LEVEL ANTICYCLONE KEEPS ITS FURNACE-LIKE GRIP ON THE REGION.
WELL ABOVE NORMAL TEMPERATURES EXPECTED AGAIN TOMORROW AFTERNOON
WITH SOME CONVECTION AGAIN BREAKING OUT OVER THE HIGHER TERRAIN.
CONVECTIVE PROBABILITIES SATURDAY WILL DECREASE QUICKLY AS ONE
MOVES AWAY FROM THE MOUNTAINS...SIMILAR TO TODAY.
LONG TERM...SOME CHANGES AS WE GET INTO NEXT WEEK. UPPER RIDGE
WILL SHIFT EAST ALLOWING FOR MOISTURE TO INCREASE AGAIN BY MONDAY.
MEANWHILE A SHORT WAVE TROUGH MOVING ACROSS THE NORTHERN U.S.
BORDER WILL PUSH SOME LESS HOT LOW LEVEL AIR SOUTHWARD ON MONDAY.
THE MAIN IMPACTS LOOK LIKE THE LOW LEVEL COOLING...AND HIGH LEVEL
MOISTENING. THIS COULD WIND UP BEING SIMILAR TO THE COOLER PERIODS
WE HAD 5 TO 10 DAYS AGO WHEN IT WAS WARM AND MOIST...BUT NOT WARM
ENOUGH TO SUPPORT LOTS OF CONVECTION DUE TO THE CLOUD COVER AND
NOT MUCH COOLING ALOFT. MODELS WANT TO PRODUCE INCREASED
PRECIPITATION IN THE MONDAY THROUGH THURSDAY TIME PERIOD...BUT I
AM HESITANT TO RAISE POPS TOO MUCH DUE TO THE STABILITY ISSUE.
THERE WILL PROBABLY BE MORE CONVECTIVE ACTIVITY...BUT OVERALL IT
WILL LIKELY BE WEAK. POSSIBLE EXCEPTION WILL BE MONDAY WHEN THERE
COULD BE BOTH LOW LEVEL CONVERGENCE AND A LITTLE UPPER LEVEL
DIVERGENCE THAT COULD SUSTAIN SOMETHING MORE ORGANIZED.
TEMPERATURES WILL BE AFFECTED AS MUCH BY THE CLOUD COVER AS THE
ACTUAL COOLING...MINIMUM TEMPERATURES MAY STILL BE PRETTY MILD.
SLIGHT WARMING AND DRYING DURING THE LATER PART OF THE WEEK BUT WE
WILL STILL BE UNDER SW FLOW ALOFT AND PROBABLY STILL A LOT OF HIGH
CLOUDINESS. RIDGE REBUILDS BY NEXT WEEKEND...HARD TO TELL HOW MUCH
CLOUD COVER THERE WILL BE...IF IT DRIES OUT A BIT WE WILL LIKELY
BE NEAR RECORD HIGHS AGAIN...THOUGH PROBABLY NOT AS HOT AS WE ARE
NOW.
AVIATION...THUNDERSTORM THREAT LOOKS PRETTY SMALL AT THE
TERMINALS THIS EVENING AND AGAIN ON SATURDAY. WINDS ARE BEHAVING
ABOUT AS EXPECTED AT THIS POINT. SOME OF THE SMALLER SCALE MODELS
ARE SUGGESTING A MODERATELY STRONG OUTFLOW BOUNDARY WILL MOVE
ACROSS THE TERMINALS TOWARDS 00Z. PRESENT TAFS HAVE THIS SUGGESTED
WITH THE WESTERLY WINDS AT 00Z. NORMAL DIURNAL PATTERNS LATER
TONIGHT.
HYDROLOGY...CONVECTIVE ACTIVITY IS MOVING NORTHWARD AT A DECENT
CLIP THIS AFTERNOON. STRONG STORMS MOVED ACROSS THE HIGH PARK BURN
AREA EARLY THIS AFTERNOON AND ADDITIONAL STORMS MAY CROSS THAT
AREA AS WELL AS FOUR MILE LATER TODAY. THESE STORMS WILL POSE SOME
FLOODING THREAT. A SIMILAR SITUATION WILL EXIST SATURDAY
AFTERNOON.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ENTREKIN
LONG TERM....GIMMESTAD
AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS TAUNTON MA
649 AM EDT THU SEP 5 2013
.SYNOPSIS...
A SHARP COLD FRONT WILL SWEEP ACROSS THE REGION THIS MORNING WITH
A FEW BRIEF SHOWERS. DRY WEATHER FOLLOWS WITH UNSEASONABLY COOL
CONDITIONS LATE TODAY INTO FRIDAY. TEMPERATURES MODERATE TO
SEASONAL LEVELS THIS WEEKEND...BEFORE ANOTHER COLD FRONT BRINGS
SOMEWHAT COOLER AIR EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
645 AM UPDATE...
LOWERED RAINFALL CHANCES THIS MORNING BASED ON LATEST RADAR
DATA...WHICH IS SHOWING RAINFALL DRYING SLIGHTLY AS IT MOVES EAST.
MOST OF THE RAPID REFRESH MODELS..SUCH AS THE HRRR AND RAP...ARE
CONSISTENTLY SHOWING A SLIGHT INCREASE IN COVERAGE FROM PRESENT
LATER THIS MORNING AS THE COLD FRONT MOVES INTO CENTRAL AND
EASTERN MA. THIS MAKES SENSE AS WE WILL BE AFTER SUNRISE...AND THE
LOW LEVEL LAPSE RATES SHOULD BE AT LEAST A LITTLE MORE FAVORABLE.
OTHERWISE...THE TIMING OF THE PREVIOUS FORECAST LOOKS GOOD WITH
A COLD FRONT MOVING OFFSHORE AROUND NOON. MADE MINOR TWEAKS TO
TEMPERATURES AS WELL TO BRING THEM IN LINE WITH OBSERVED TRENDS.
PREVIOUS DISCUSSION...
SFC OBS AND MSAS SUGGEST STRONG SFC COLD FRONT IS JUST ON THE NW
DOORSTEP OF BOX CWA THIS HOUR...HAVING ALREADY MOVED THROUGH
CENTRAL VT/NH. PRECIP HAS BEEN VERY CLOSELY ASSOCIATED WITH THIS
FRONT GIVEN LACK OF DEEP MOISTURE FLUX /MOISTURE IS LIMITED TO THE
H85-H5 LAYER/ AND REQUIRES ALL FRONTOGENETICAL FORCING. AM NOTING
A FAIR AMOUNT OF DRYING OF THESE -SHRA AS THEY APPROACH THE VERY
DRY AIRMASS ALREADY IN PLACE OVER SRN NEW ENGLAND.
THEREFORE...DESPITE THE MOISTURE AND LATEST MODEL TREND TO LEAN
TOWARD LIKELY- CATEGORICAL POPS WILL CONTINUE TO CAP POPS AT
CHANCE AS THE FRONT SLIDES THOUGH THIS MORNING. TIMING THIS FRONT
TO REACH SRN NH AND THE MASS BORDER BY 09-10Z...CENTRAL MA BY
13-14Z AND TO THE S COAST BY ABOUT 16-18Z. TIMING OF HIGHEST POPS
FOLLOW THE TIMING OF THE FRONT. IT IS POSSIBLE HOWEVER...GIVEN THE
LACK OF MOISTURE AND RECENT RADAR TRENDS...THAT MANY LOCATIONS MAY
REMAIN DRY WITH THIS FROPA. AREAS THAT DO SEE RAINFALL WILL LIKELY
ONLY SEE ENOUGH TO WET THE GROUND.
STRONG COLD ADVECTION AND SOME CLOUD COVER WITH THIS FRONT SUGGEST
A NON-DIURNAL TEMP TREND WITH THE HIGHS LIKELY ARRIVING ABOUT MID
DAY TO EARLY AFTERNOON WITH GRADUAL DECREASES INTO THE EVENING
HOURS. LATEST MAV/MET GUIDANCE SHOWS THIS WELL. CLOUDS ARE LIKELY
TO RAPIDLY DISSIPATE TO NEAR SKC CONDITIONS BY THIS EVENING AS DRY
AIR WORKS IN WITH HIGH PRES AND THE ACCOMPANYING CAA. WINDS WILL
ALSO BE BRIEFLY GUSTY...REACHING 20+ MPH AT TIMES JUST BEHIND THE
FRONT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
TONIGHT...
STRONG COLD ADVECTION CONTINUES INITIALLY ALLOWING H85 TEMPS TO
DIP AS LOW AS +2C BY THE EVENING HOURS. THE PRIMARY EFFECT FROM
THIS WILL BE THE POSSIBILITY OF SOME OCEAN EFFECT CLOUDS AND
POSSIBLY EVEN LIGHT SHOWERS WHICH MAY EFFECT THE CAPE/ISLANDS
OVERNIGHT WITH N FLOW. GIVEN THE DIFFERENCE WITH SST/S AROUND +18
TO +20C THERE SHOULD BE ENOUGH NEAR SFC INSTABILITY TO GENERATE
THESE OCEAN EFFECT CLOUDS. WILL KEEP POPS OUT FOR THE TIME BEING
AS WELL MIXED AND DRY BL MAY KEEP ANY -SHRA FROM REACHING THE SFC.
OTHERWISE...SKC CONDITIONS IN THE INTERIOR AND SLACKENING MASS
FIELDS SUGGEST GOOD RADIATIONAL COOLING WHICH COULD LEAD SOME
VALLEYS IN THE NW PORTIONS OF THE CWA TO DIP BELOW THE 36F
THRESHOLD DURING THE EARLY MORNING HOURS. THEREFORE...WILL BE
ISSUING A STATEMENT FOR THE THREAT OF SOME PATCHY FROST IN
TYPICALLY COLDER VALLEYS. WILL LIMIT THE STATEMENT TO CHESHIRE
COUNTY IN NH...AS WELL AS FRANKLIN AND NORTHERN WORCESTER COUNTIES
IN MA. DAY CREW MAY NEED TO CONSIDER A FULL FLEDGED FROST ADVISORY
IF MODEL COOLING TREND CONTINUES. ELSEWHERE...EVEN THOUGH PLACES
WILL BE TOO COOL FOR FROST WILL STILL BE MUCH COOLER THAN PREVIOUS
NIGHTS...WITH TEMPS RANGING FROM THE MID 30S TO MID 40S.
FRI...
COOL START TO THE DAY WILL WITH FULL SUNSHINE WILL REALIZING THE
INCREASING H85 TEMPS THROUGH THE DAY. THESE TEMPS SHOULD TOP OUT
AT ABOUT +6C BY LATE AFTERNOON. THEREFORE...MAX TEMPS GENERALLY
REMAIN AT OR BELOW THE 70F MARK FOR THE DAY. HIGH PRES REMAINS IN
CONTROL WITH DRY WX.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...
* MAINLY DRY WEATHER THROUGH THE MIDDLE OF NEXT WEEK
* TEMPERATURES MODERATE TO NEAR NORMAL THIS WEEKEND
DETAILS...
FRIDAY NIGHT AND SATURDAY...
EXPECTING GOOD RADIATIONAL COOLING CONDITIONS FRIDAY NIGHT...BUT LOW
TEMPERATURES WILL NOT BE QUITE AS CHILLY AS THURSDAY NIGHT. AFTER A
COOL START EARLY SATURDAY...A HIGH PRESSURE MOVING OFF THE COAST
WILL ALLOW FOR A RETURN SOUTHWEST FLOW OF AIR INTO SOUTHERN NEW
ENGLAND. PLENTY OF SUNSHINE EARLY IN THE DAY...BUT WE SHOULD SEE AN
INCREASE IN MID AND HIGH CLOUDS DURING THE AFTERNOON IN THE WARM AIR
ADVECTION PATTERN.
SATURDAY NIGHT AND SUNDAY...
A COLD FRONT WILL MOVE ACROSS THE REGION SOMETIME SUNDAY. THERE IS
LITTLE MOISTURE OR INSTABILITY AHEAD OF THIS FRONT...BUT CANNOT RULE
OUT A BRIEF SPRINKLE/SPOT SHOWER OR TWO SOMETIME DURING THIS TIME
FRAME. EVEN IF THIS HAPPENS THOUGH...THE VAST MAJORITY OF THE TIME
WILL BE DRY SO HAVE MAINTAINED LOW POPS.
MONDAY THROUGH WEDNESDAY...
DRY BUT SOMEWHAT COOLER WEATHER EXPECTED MONDAY BEHIND A COLD FRONT.
HOWEVER...AIRMASS DOES NOT LOOK AS CHILLY AS WHAT WE WILL HAVE THIS
LATE THIS WEEK...WITH THE CORE OF COLDER AIR OVER NORTHERN NEW
ENGLAND. A HIGH PRESSURE SHOULD MOVE OFF THE COAST ALLOWING FOR A
RETURN OF WARMER AIR FOR TUESDAY AND ESPECIALLY WEDNESDAY. DRY
WEATHER SHOULD PREVAIL MOST OF THE TIME THROUGH WEDNESDAY. A WARM
FRONT PASSING NEARBY MAY BE ENOUGH TO TRIGGER ISOLATED SHOWERS IF
ENOUGH MOISTURE CAN BE POOLED TOGETHER TUESDAY INTO WEDNESDAY.
&&
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
OVERVIEW /THROUGH FRIDAY/...HIGH CONFIDENCE OVERALL...
MAINLY VFR THROUGH THE PERIOD. HOWEVER A PERIOD OF -SHRA WILL MOVE
ACROSS THE REGION FROM N TO S FROM ABOUT 08Z-18Z...EXITING
OFFSHORE AFTER 18Z...AND THERE MAY BE LOCALIZED MVFR CONDITIONS
WITHIN THESE -SHRA. OTHERWISE...SOME MVFR CIGS ARE POSSIBLE OVER
THE CAPE/ISLANDS LATE THIS EVENING AS SOME OCEAN EFFECT CLOUDS
DEVELOP. WIND GUSTS 15-20 KT POSSIBLE AT TIMES ONCE WINDS SHIFT TO
THE NNW THIS MORNING BEHIND THE COLD FRONT.
KBOS TERMINAL...GENERALLY HIGH CONFIDENCE IN TAF...ALTHOUGH A
BRIEF PERIOD OF MVFR IS POSSIBLE IN SOME -SHRA THIS MORNING.
ALSO...WINDS MAY SHIFT MORE NNE BEHIND THE COLD FRONT MID MORNING
INTO THE AFTERNOON.
KBDL TERMINAL...HIGH CONFIDENCE IN TAF.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
HIGH CONFIDENCE IN MAINLY VFR CONDITIONS THROUGH THE PERIOD. MAY
SEE SOME VERY LOCALIZED PATCHY GROUND FOG IN THE TYPICALLY PRONE
LOCATIONS DURING THE LATE NIGHT/EARLY MORNING HOURS. THERE ALSO IS
LOW PROBABILITY OF BRIEF MVFR CONDITIONS SAT NIGHT AND EARLY
SUNDAY IN SHOWERS AHEAD OF A COLD FRONT.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
SHORT TERM /THROUGH THURSDAY NIGHT/...HIGH CONFIDENCE.
MAIN ISSUE TODAY WILL BE THE THREAT FOR OCCASIONAL SMALL CRAFT
ADVISORY LEVEL WINDS ESPECIALLY AROUND THE MID DAY PERIOD. WIND
GUSTS MAY APPROACH 25 KT AT TIMES...BUT THE TIMING WILL BE SHORT
LIVED AND MANY GUSTS WILL STAY BELOW THIS THRESHOLD.
THEREFORE...WILL HOLD OFF ON ANY HEADLINES BUT MENTION THE THREAT
FOR A FEW GUSTS TO 25 KT IN THE COASTAL FORECAST.
OTHERWISE...HIGH PRES BUILDS OVER THE WATERS LATE TONIGHT INTO
TOMORROW WITH GENERAL DRY AND QUIET BOATING WEATHER EXPECTED.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT...HIGH CONFIDENCE. HIGH PRESSURE OVERHEAD WILL KEEP
WINDS/SEAS WELL BELOW SMALL CRAFT ADVISORY THRESHOLDS.
SATURDAY...MODERATE CONFIDENCE. HIGH PRESSURE MOVING EAST OF THE
WATERS WILL ALLOW FOR SOUTHWEST WINDS TO DEVELOP. CONDITIONS SHOULD
GENERALLY REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS...BUT A
PERIOD OF SOUTHWEST WIND GUSTS OF 20 TO 25 KNOTS ARE POSSIBLE ACROSS
THE NEAR SHORE WATERS OF THE SOUTH COAST DURING THE AFTERNOON. THIS
MAY RESULT IN SOME CHOPPY SEAS ACROSS THE SOUNDS AND BAYS.
SUNDAY AND MONDAY...MODERATE CONFIDENCE. A PERIOD OF NORTHERLY SMALL
CRAFT ADVISORY WIND GUSTS AND SEAS ARE POSSIBLE LATE SUNDAY INTO
EARLY MONDAY BEHIND A COLD FRONT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...BELK/DOODY
SHORT TERM...DOODY
LONG TERM...BELK
AVIATION...BELK/DOODY
MARINE...BELK/DOODY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
930 PM EDT FRI SEP 6 2013
.UPDATE...
CURRENTLY/OVERNIGHT...REMNANT STRATIFORM RAIN FROM AFTERNOON/EVENING
MCS HAS JUST ABOUT DISSIPATED. CONSIDERABLE DEBRIS CLOUDINESS WILL
COVER THE AREA PAST MIDNIGHT. HIGH PRESSURE TO THE NORTH IS
FORECAST TO BRIDGE ACROSS THIS WEAK FRONT AND PRODUCE LIGHT
NORTHEAST WINDS OVERNIGHT. THE LATEST HRRR MODEL DOES NOT SHOW ANY
ADDITIONAL PRECIP OVERNIGHT BUT OUR LOCAL WRF SHOWS SOME SHOWERS
DEVELOPING ALONG THE TREASURE COAST. THIS IS ENTIRELY UNDERSTANDABLE
AS MOISTURE DEPTH IS FORECAST TO BE THE GREATEST THERE AND LOW LEVEL
FLOW SHOULD BE WEAKLY CONFLUENT DUE TO THE WEAKENING FRONTAL
TROUGH. SO NOT PLANNING TO CHANGE THE CURRENT FORECAST MUCH.
&&
.AVIATION...MAIN ISSUE IS LOW STRATUS THAT RECENTLY DEVELOPED.
WOULD THINK THAT IT WILL NOT BE AN ALL NIGHT THING AS LOW LEVEL FLOW
IS FORECAST TO SWING AROUND TO THE NORTHEAST. HOWEVER WITH WEAKLY
LOW LEVEL CYCLONIC FLOW I HAVE SEEN LOW CLOUDS HANG AROUND LONGER
THAN EXPECTED...BUT THAT IS TYPICALLY IN THE COOL SEASON...SO HAVE
NOT CARRIED THE STRATUS FOR VERY LONG INTO THE NIGHT. DID NOT LOOK
REAL CLOSE AT THE SAT FORECAST BUT THE MODELS HAVE BEEN BRINGING
DRYING ALOFT INTO THE AREA FROM THE NORTH SO THE CHANCES FOR
AFTERNOON STORMS LOOK MUCH LOWER...20 PERCENT OR LESS.
&&
.MARINE...
TONIGHT-SAT...A WEAK NORTHEAST FLOW IS FORECAST TO SET IN OVERNIGHT
THEN PICK UP TO AROUND 10 KNOTS ON SAT. A SMALL EAST SWELL SHOULD
KEEP SEA HEIGHTS ELEVATED TO 3-4 FEET OFFSHORE. A SMALL CHANCE FOR
SHOWERS OR STORMS SHOULD BE CONFINED TO SOUTH OF CANAVERAL AND MAYBE
EVEN SOUTH OF SEBASTIAN INLET.
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
FORECASTS...LASCODY
IMPACT WX/RADAR...WIMMER
AREA FORECAST DISCUSSION
NWS MIAMI FL
847 PM EDT FRI SEP 6 2013
.UPDATE...
ALTHOUGH IT WAS A LATE START FOR THE AFTERNOON SHOWERS AND
STORMS...A LARGE AREA OF HEAVY SHOWERS AND STORMS HAS DEVELOPED
AND BECOME FOCUSED OVER THE GULF COAST AREAS FROM NAPLES TO
EVERGLADE CITY TO CENTRAL COLLIER COUNTY THIS EVENING. THE LATEST
RADAR SCAN ESTIMATED TOTALS RANGING FROM HALF OF AN INCH OVER THE
BULK OF THIS AREA WITH ISOLATED AMOUNTS AS HIGH AS 2.5". THE
LATEST HRRR MODEL REFLECTIVITIES LINE UP WELL WITH THIS ACTIVITY
AND GENERALLY CONTINUES TO SUPPORT THIS COVERAGE WELL INTO THE
LATE EVENING HOURS BEFORE DISSIPATING. IF THIS VERIFIES...AN
ADDITIONAL HALF OF AN INCH TO ONE INCH WITH LOCALLY HIGHER AMOUNTS
WILL BE EXPECTED. THE LATEST FORECAST PACKAGE HAS BEEN UPDATED TO
REFLECT THESE LATEST TRENDS. OTHERWISE...THE PREVIOUS FORECAST
REMAINS ON TRACK THIS EVENING.
&&
.PREV DISCUSSION... /ISSUED 736 PM EDT FRI SEP 6 2013/
AVIATION...
VFR PREVAILING AT ALL TERMINALS. VCTS ONLY FOR KAPF THIS EVENING
DUE TO THE ACTIVITY ALREADY NEARBY. EXPECT THIS TO DISSIPATE BY
04Z. VCSH WILL POSSIBLY DEVELOP NEAR ALL EASTERN TERMINALS BY
07/16Z AND WEST COAST SEA BREEZE DEVELOPING BY 07/18Z. VCTS WILL
BE POSSIBLE NEAR KAPF BY THAT TIME ALSO.
PREV DISCUSSION... /ISSUED 230 PM EDT FRI SEP 6 2013/
.TYPICAL SUMMER TIME WEATHER THIS WEEKEND BEFORE DRIER
CONDITIONS EARLY NEXT WEEK...
SHORT TERM...
THE EAST AND WEST COAST SEA BREEZES HAVE DEVELOPED EARLY THIS
AFTERNOON WITH THE EAST COAST SEA BREEZE PUSHING ACROSS THE
INTERIOR AREAS. THE EAST COAST SEA BREEZE WILL CONTINUE TO PUSH
WEST ACROSS SOUTH FLORIDA THROUGH THE AFTERNOON HOURS...AS THE
WEST COAST SEA BREEZE REMAINS OVER THE WEST COAST METRO AREAS. AT
THE SAME TIME...A TROUGH OF LOW PRESSURE OVER NORTH FLORIDA WILL
CONTINUE TO MOVE SOUTH INTO CENTRAL FLORIDA. THIS WEATHER PATTERN
WILL ALLOW FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP OVER THE INTERIOR AND WEST COAST METRO AREAS THIS
AFTERNOON INTO EARLY THIS EVENING...WITH ISOLATED SHOWERS ONLY FOR
THE EAST COAST METRO AREAS. SO WILL KEEP THE 30 TO 50 PERCENT POPS
IN PLACE FOR THE INTERIOR AND WEST COAST METRO AREAS THROUGH EARLY
THIS EVENING...WITH ONLY A 20 PERCENT POPS OVER THE EAST COAST
METRO AREAS OF SOUTH FLORIDA.
THE TROUGH OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY TONIGHT
OVER CENTRAL FLORIDA...BEFORE MOVING SLOWLY SOUTH INTO THE LAKE
OKEECHOBEE AREA ON SATURDAY AND THROUGH SOUTH FLORIDA ON SUNDAY.
THIS WILL KEEP THE STEERING FLOW OVER SOUTH FLORIDA IN A LIGHT
NORTHEAST DIRECTION ALONG WITH THE SEA BREEZE DEVELOPMENT EACH DAY
ALONG BOTH COAST. SO THE SCATTERED POPS WILL REMAIN OVER THE
INTERIOR AND WEST COAST METRO AREAS WITH ISOLATED POPS OVER THE
EAST COAST METRO AREAS EACH DAY THIS WEEKEND. THE THREAT OF
THUNDER WILL ALSO BE FOCUS MAINLY OVER THE INTERIOR AND WEST COAST
METRO AREAS EACH DAY THIS WEEKEND..BUT THE EAST COAST METRO AREAS
COULD SEE A THUNDERSTORM OR TWO.
THE 500 MB TEMP WILL ALSO REMAIN VERY COLD FOR THIS TIME OF YEAR
IN THE -8C TO -9C OVER SOUTH FLORIDA. THIS WILL ALLOW FOR SOME OF
THE STORMS EACH DAY THIS WEEKEND TO BECOME STRONG OVER SOUTH
FLORIDA ESPECIALLY WHERE THE SEA BREEZES COLLIDE EACH DAY. THE
PRIMARY IMPACTS FROM THE STRONG STORMS WILL MORE LIKELY BE
LIGHTNING STRIKES, GUSTY WINDS, AND HAIL. SO WILL MENTION THIS IN
THE AFTERNOON HWO PACKAGE.
LONG TERM...
THE TROUGH OF LOW PRESSURE WILL MOVE INTO THE FLORIDA KEYS EARLY
NEXT WEEK BEFORE MOVING BACK UP INTO SOUTH FLORIDA FOR THE MIDDLE
OF NEXT WEEK...AS AN UPPER LEVEL LOW DEVELOPS OVER THE WESTERN
ATLANTIC WATERS. THIS WILL ALLOW FOR SOME DRIER AIR TO WORK INTO
SOUTH FLORIDA FROM THE NORTH EARLY NEXT WEEK...BEFORE MOISTURE
RETURNS TO THE AREA FOR MIDDLE OF NEXT WEEK. THEREFORE...THE POPS
FOR EARLY NEXT WEEK HAVE BEEN LOWER TO SLIGHT CHANCE OVER MOST
OF SOUTH FLORIDA EXCEPT LOW END CHANCE OVER THE WESTERN AREAS.
FOR MIDDLE OF NEXT WEEK...THE POPS WILL REMAIN IN THE CHANCE CAT
OVER SOUTH FLORIDA.
AVIATION...
A WEAK TROUGH IS TRYING TO MAKES ITS WAY INTO SOUTH FLORIDA THIS
AFTERNOON. THIS SHOULD ACT TO ENHANCE CONVECTION IN THE WESTERN
HALF OF THE AREA. THE SEA BREEZE WILL KEEP THE EAST COAST CLEAR OF
MOST CONVECTION, ALTHOUGH AN ISOLATED SHOWERS MAY STILL TRY TO
FORM. GIVEN THIS, HAVE KEPT ANY SHRA/TSRA OUT OF THE EASTERN SITES
THIS AFTERNOON. FOR KAPF, HAVE DELAYED VCTS FOR A FEW HOURS AS THE
MODELS INDICATE IT WILL BE MORE TOWARDS THE MID AFTERNOON BEFORE
CONVECTION AFFECTS NAPLES. HOWEVER, THIS COULD BE OFF A LITTLE, SO
VCTS MAY NEED TO ADDED, OR EVEN DELAYED SOME, BASED ON DEVELOPMENT.
WINDS WILL BE GENERALLY EASTERLY THIS AFTERNOON, WITH THE
EXCEPTION OF KAPF, WHERE THE GULF BREEZE IS EXPECTED TO JUST MAKE
IT PAST THE AIRPORT. TONIGHT, WINDS WILL LIGHTEN AND GO VARIABLE
IN MANY LOCATIONS. THEY WILL ONCE AGAIN BECOME EASTERLY TOMORROW
BETWEEN 5 AND 10 KTS.
MARINE...
THE WINDS WILL REMAIN FROM THE EAST NORTHEAST AT 10 KNOTS OR LESS
THIS WEEKEND INTO EARLY NEXT WEEK OVER ALL OF SOUTH FLORIDA
WATERS. THIS WILL KEEP THE SEAS IN BOTH THE ATLANTIC AND GULF
WATERS AT 2 FEET OR LESS. SO BOATING CONDITIONS WILL BE GOOD OVER
ALL OF SOUTH FLORIDA WATERS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 77 89 77 88 / 20 30 20 20
FORT LAUDERDALE 79 89 79 89 / 20 20 20 20
MIAMI 78 90 78 89 / 20 30 20 20
NAPLES 74 91 74 91 / 70 30 30 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...17/ERA
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1248 AM CDT THU SEP 5 2013
.DISCUSSION...
840 PM CDT
FOR EVENING UPDATE...
MAINLY ONLY MINOR ADJUSTMENTS BASED ON OBS/SATELLITE TRENDS THIS
EVENING.
SURFACE COLD FRONT WAS JUST ENTERING FAR NORTHEASTERN LAKE COUNTY
IL AT 01Z PER SFC OBS AND EXTRAPOLATION OF BOUNDARY THAT WAS
PROMINENT EARLIER IN KMKX REFLECTIVITY DATA. FRONT WILL CONTINUE
TO BACK-DOOR ITS WAY ACROSS NORTHEAST IL THROUGH THE REMAINDER OF
THE EVENING HOURS AND EVENTUALLY PUSHING INTO CENTRAL IL/IN
OVERNIGHT. WHILE COOLER TEMPS WILL SPREAD IN BEHIND THE FRONT...IT
APPEARS THE STRONGER COOLING/DRYING WILL LAG THE FRONT INTO THE
DAY THURSDAY GIVEN MODEST NORTHEAST WINDS OVERNIGHT.
TEMPS/HUMIDITY WILL ACTUALLY BE A LITTLE HIGHER BEHIND THE FRONT
TONIGHT THAN LAST NIGHT.
GOES 11-3.9 MICRON IR IMAGERY DOES INDICATE AREA OF LOW CLOUDS
(1100-1400 FT BASES) DEVELOPING BEHIND THE FRONT FROM EASTERN WI
INTO WESTERN LOWER MICHIGAN AT 01Z...THOUGH 18Z WRF-NAM SOUNDINGS
AND TSECTS APPEAR TO HAVE BACKED OFF A BIT ON THE DEPTH OF MOISTURE
THAT DEVELOPS OVER FAR NORTHERN/NORTHWESTERN IL BEHIND THE FRONT
OVERNIGHT AS WELL AS AREA OF LIGHT PRECIP OVER NORTHWEST IL. 00Z
RAOB ANALYSIS AT 925-850MB LEVELS DOES INDICATE LOW LEVEL THERMAL
RIDGE ALONG IA/MN BORDER REGION THAT MAY CONTINUE TO SUPPORT SOME
ASCENT ABOVE THE LOW LEVEL FRONTAL ZONE GIVEN STRONG NORTHWESTERLY
JET AND PRESENCE OF SHEARED MID-LEVEL SHORT WAVE...SO AM A LITTLE
HESITANT TO PULL CLOUDS/SPRINKLES OF GOING FORECAST. WILL SHIFT
TIMING A COUPLE HOURS PAST MIDNIGHT BUT OTHERWISE LEAVE ALONE AT
THIS POINT WITH LOCAL 8 KM WRF-ARW RUN ALSO STILL PRODUCING A LITTLE
QPF OVER SOUTHWEST WI/NORTHWEST IL TOWARD MORNING.
OTHERWISE...OTHER THAN ADJUSTMENTS TO HOURLY TEMP/WIND AND SKY COVER
GRIDS NO OTHER SIGNIFICANT CHANGES MADE TO NEAR TERM OF FORECAST FOR
THE OVERNIGHT HOURS.
RATZER
//PREV DISCUSSION...
300 PM CDT
THE FORECAST CHALLENGES ARE MAINLY TEMPERATURES AS SUMMER LOOKS TO
WIN OUT OVER AUTUMN IN THE EARLY GOING OF SEPTEMBER.
SYNOPSIS...IMPRESSIVELY DEEP UPPER TROUGH OVER EASTERN CANADA IS
BEING REINFORCED THIS AFTERNOON WITH A VIGOROUS JET DIVING INTO
THE UPPER GREAT LAKES. AS A GEE-WHIZ AND A SIGN OF THE CHANGE IN
SEASONS...NOT HERE YET BUT UP NORTH...850MB TEMPS AT CWZC ON THE
SOUTHERN END OF JAMES BAY DROPPED FROM +11C LAST NIGHT TO -5C THIS
MORNING UNDER THAT UPPER TROUGH. AN ASSOCIATED SURFACE COLD FRONT
IS DRAPED FROM LAKE ONTARIO THROUGH CENTRAL WI INTO SOUTHERN MN.
THIS FRONT HAS BEEN MOVING SLOWLY BUT CONSISTENTLY SOUTHWARD TODAY
WITH A RIBBON OF STRATUS/STRATOCU BEHIND IT. ALSO SEEN UPSTREAM IS A
SHEARING OUT SHORTWAVE ACROSS NW MN WHICH WILL CONTINUE TO MOVE
SOUTHEASTWARD.
TONIGHT...GIVEN THE COLD FRONT ORIENTATION AND THE LOSS OF MIXING
OF WESTERLY WINDS...EXPECT THE SURFACE COLD FRONT TO PROGRESS
QUICKER DOWN THE LAKE THIS EVENING...REACHING CHICAGO BY JUST
AFTER SUNDOWN OR SO. THIS WILL MEAN A TURN TO NORTHEAST WINDS AND
A DROP IN TEMPERATURE BY SEVERAL DEGREES LIKELY IN JUST A COUPLE
HOURS. READINGS SHOULD THEN STABILIZE NEAR THE LAKE GIVEN THE
STILL MILD WATER TEMPERATURES. THE NAM AND RAP SOUNDINGS ALONG
WITH COLD AIR ADVECTION AND RH FIELDS SUPPORT AT LEAST PATCHY
STRATUS MAKING IT DOWN INTO THE AREA NOT LONG BEHIND THE FRONT.
LOW-LEVEL THERMAL PROFILES ALSO HOVER AROUND LAPSE RATES
SUPPORTIVE OF LAKE-INDUCED CLOUDS. WITH THESE FORECASTS MESHING
WITH OBSERVATIONAL TRENDS UPSTREAM...HAVE BUMPED UP SKY COVER
LATER THIS EVE INTO OVERNIGHT. ALSO...AFOREMENTIONED SHEARING
SHORT WAVE OVER NW MN WILL RIDE A TIGHT 600-800MB THERMAL GRADIENT
INTO NW/NC IL BY EARLY OVERNIGHT. NAM FORECAST SOUNDINGS OVER RFD
WOULD CONTINUE TO SUPPORT A CHANCE FOR SOME SPRINKLES LATE AS THE
WAVE OVERRIDES SOME OF THE LOWER LEVEL MOISTURE. SO CONTINUE THAT
IN THE FORECAST BUT HAVE JUST BACKED UP IN TIME. WHILE A COLD
FRONT IS EASING THROUGH...TEMPERATURES WILL END UP SEVERAL DEGREES
WARMER THAN LAST NIGHT WITH MORE OF A WIND COMPONENT AND
INCREASING CLOUD COVER ACTING AS INSULATION.
THURSDAY THROUGH SATURDAY...FAIRLY QUIET WEATHER INTO FRIDAY
CONTINUES TO BE THE TREND IN THE WEATHER PATTERN. NORTHEAST WINDS
WILL CONTINUE INTO THU WITH TEMPERATURES IN THE 70S ACROSS AREAS
NORTH OF I-80. WARM AIR ADVECTION BEGINS FRIDAY AS THE HIGHS
SHIFTS EAST. THE 04.00 EC WAS FAIRLY SHARP WITH THIS ALOFT AND
HAVING A COINCIDENT SHORT WAVE WITH OUTPUT QPF. ITS MORE CURRENT
RUN IS MORE IN LINE WITH OTHER GUIDANCE...THAT IS DRIER AND
CONTINUE AS SUCH IN THE FORECAST. NEXT SHORT WAVE DROPS OVER THE
GREAT LAKES WITH ASSOCIATED WEAK SURFACE COLD FRONT OOZING
SOUTHWARD ON SAT. BEST LAPSE RATES AND MOISTURE ARE REALLY
CONFINED TO THE FRONT...SO DO NOT INTRODUCE SHOWER CHANCES UNTIL
SAT AFTERNOON AND AT THAT LOW AT THIS TIME. TEMPS RIGHT NOW LOOK
TO BE IN THE MID 80S FOR SAT GIVEN LOCAL CLIMATOLOGY...AND GIVEN
LOW-LEVEL THERMAL VALUES WHAT THEY WERE TODAY BUT WITH EVEN MORE
SW ADVECTION.
MTF
EXTENDED FORECAST SAT NIGHT-WED...WEAK COLD FRONT CONTINUES TO DROP
SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY. WILL KEEP LOW
POPS FOR SATURDAY NIGHT...AND FOR THE SOUTHERN PART OF THE FORECAST
AREA SUNDAY. HIGH PRESSURE MOVES ACROSS THE LAKES SUNDAY WITH
NORTHEAST SURFACE WINDS. THIS SHOULD BRING DRY AND A LITTLE COOLER
WEATHER...ESPECIALLY NEAR THE LAKE. SUNDAY NIGHT INTO MONDAY THE
UPPER RIDGE AXIS SHIFTS EAST TOWARD THE GREAT LAKES AND THE SURFACE
HIGH SHIFTS EAST BRINGING A RETURN TO SOUTHERLY FLOW AND WARMER
WEATHER. GUIDANCE PRODUCING SLIGHT CHANCE POPS MOST PERIODS DAYS 4
THOUGH 7 BUT DON`T SEE ANY REAL FOCUS FOR THUNDERSTORMS SUNDAY NIGHT
THROUGH MONDAY NIGHT OR TUESDAY. AS UPPER RIDGE AXIS PUSHES EAST
THROUGH THE GREAT LAKES THE HEAT DOMES SPREADS EAST. TUESDAY LOOKS
ESPECIALLY WARM WITH GFS 925 MB TEMPS 26-28C AND ECMWF EVEN A BIT
WARMER WITH STRONG WSW FLOW. LOOKING AT CIPS ANALOGS...SIMILAR
PATTERNS IN LATE AUGUST AND SEPTEMBER YIELDED SURFACE TEMPS MOSTLY
IN THE LOWER 90S. HAVE BUMPED UP MAX TEMPS OVER GUIDANCE FOR
TUESDAY. NOT GOING TO GO WILD WITH TEMPS 6 DAYS OUT...BUT WILL
CONTINUE TO MONITOR. COULD SEE NEAR RECORD HIGHS TUESDAY IF MODELS
PAN OUT AND WE GET ENOUGH SUNSHINE. UPPER TROF MOVES ACROSS THE
UPPER LAKES AND TRAILING SURFACE COLD FRONT APPROACHES THE FORECAST
AREA TUESDAY NIGHT INTO WEDNESDAY FOR THE BEST CHANCE OF
THUNDERSTORMS IN THE EXTENDED PERIOD.
ALLSOPP
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* FROPA TURNING WINDS TO THE NORTHEAST IN THE NEAR TERM...WITH AN
INCREASE IN SPEED AND GUSTS THROUGH THE MORNING.
* LOW END MVFR AND IFR CEILINGS POSSIBLE EARLY THIS MORNING.
RODRIGUEZ
//DISCUSSION...UPDATED 06Z...
MAIN CONCERN THIS FORECAST PERIOD IS IN THE NEAR TERM...WITH WINDS
TURNING TO THE NORTHEAST WITH A SLOW MOVING COLD FRONT AS WELL AS
POTENTIAL FOR LOWER CEILINGS. LATEST OBSERVATIONS INDICATING A
SLOW PROGRESSION OF THIS FRONT INTO NORTHEAST ILLINOIS...WITH
WINDS SHIFTING TO THE NORTHEAST BUT STILL REMAINING ON THE LIGHTER
SIDE. THIS TRANSITION TO THE NORTHEAST WILL OCCUR WITH ALL THE
TERMINALS WITHIN THE NEXT 1-2 HOURS...WITH WINDS INITIALLY
REMAINING LIGHT. THEN AS THE GRADIENT PICKS UP...SHOULD SEE AN
INCREASE IN SPEEDS/GUSTS THROUGH THE REMAINDER OF THE MORNING.
LATEST SATELLITE IMAGERY DEPICTING AREA OF LOW END MVFR/IFR
CEILINGS INCREASING IN COVERAGE AS THEY SPILL SOUTH INTO NORTHEAST
ILLINOIS. WITH THIS INCREASE IN COVERAGE AND SHORT TERM GUIDANCE
SHOWING THIS LOW LEVEL MOISTURE MOVING ACROSS THE TERMINALS...HAVE
INCLUDED A PERIOD OF LOWER CEILINGS EARLY THIS MORNING.
ALTHOUGH...CONFIDENCE AS TO THE DURATION OF THE LOWER CEILINGS IS
SOMEWHAT LOWER AS THESE LOW CLOUDS SHOULD REMAIN PROGRESSIVE
WITHOUT ANY FURTHER EXPANSION ON THE BACKSIDE. WITH THE DEPARTURE
OF THESE CLOUDS...EXPECT VFR CONDITIONS THROUGH THE REMAINDER OF
THE FORECAST PERIOD.
RODRIGUEZ
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE WITH WIND SPEED AND DIRECTION.
* MEDIUM CONFIDENCE WITH CEILING TRENDS THIS MORNING.
RODRIGUEZ
//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...
FRIDAY...VFR. WX NIL.
SATURDAY...CHANCE TSRA LATE AFTERNOON AND OVERNIGHT.
SUNDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
MONDAY...SLIGHT CHANCE OF TSRA EARLY...OTHERWISE VFR.
TUESDAY...SLIGHT CHANCE OF TSRA...OTHERWISE VFR.
KREIN
&&
.MARINE...
229 PM CDT
A COLD FRONT IS STARTING TO MAKE ITS WAY DOWN LAKE MICHIGAN THIS
AFTERNOON WITH A PUSH OF NORTH-NORTHEASTERLY FLOW BEHIND THE FRONT
INCREASING THE WINDS INTO THE 15 TO 20 KT RANGE WITH OCCASIONAL
GUSTS TO 25 KT POSSIBLE. THE FRONT SHOULD CLEAR THE SOUTH END OF THE
LAKE AROUND MIDNIGHT TONIGHT. WITH A DECENT FETCH DOWN THE
LAKE...WAVES ARE EXPECTED TO BUILD INTO THE 3 TO 6 FT RANGE AT THE
SOUTH END OF THE LAKE PROMPTING A SMALL CRAFT ADVISORY FOR MAINLY
THE ILLINOIS NEARSHORE WATERS LATE THIS EVENING AND OVERNIGHT.
THESE CONDITIONS SHOULD SUBSIDE BACK BELOW CRITERIA THURSDAY
AFTERNOON AS HIGH PRESSURE PASSES OVER THE LAKE. AS THE HIGH
SHIFTS OVER THE EASTERN LAKES FRIDAY...SOUTHERLY FLOW INCREASES
AGAIN ACROSS THE LAKE. ANOTHER FRONT IS EXPECTED TO SAG SOUTH
ACROSS THE LAKE SATURDAY NIGHT INTO EARLY SUNDAY.
BMD
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BEACH HAZARDS STATEMENT...ILZ006-ILZ014...4 AM THURSDAY TO 5 AM
FRIDAY.
IN...BEACH HAZARDS STATEMENT...INZ001...4 AM THURSDAY TO 5 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 AM
THURSDAY TO 3 PM THURSDAY.
&&
$$
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WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1231 PM CDT THU SEP 5 2013
.SHORT TERM.../TODAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID
MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE
WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE
BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT
EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT
THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY
PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON
THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING
PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z
THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED
A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH
THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING.
.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL
PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL
REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS.
MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY
SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH
SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE
SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND
LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT
THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND
ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE
WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A
BIT.
THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING
FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY
WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH
KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO
ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO.
BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES
TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO
CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD
LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER.
THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM
IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND
ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER
THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP
CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA.
WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE
ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE
ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH
AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR
BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL
PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED.
&&
.AVIATION...05/18Z
ISSUED AT 1231 PM CDT THU SEP 5 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD WITH NO
PRECIPITATION FORECAST. THERE IS A CHANCE THAT LIGHT BR COULD FORM
EARLY FRIDAY MORNING AROUND KMCW/KALO...BUT CONFIDENCE IS TOO LOW
TO MENTION IN THE TAFS AT THIS TIME.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...SMALL
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
625 AM CDT THU SEP 5 2013
...UPDATED AVIATION DISCUSSION...
.SHORT TERM.../TODAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID
MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE
WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE
BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT
EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT
THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY
PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON
THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING
PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z
THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED
A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH
THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING.
.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL
PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL
REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS.
MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY
SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH
SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE
SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND
LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT
THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND
ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE
WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A
BIT.
THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING
FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY
WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH
KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO
ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO.
BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES
TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO
CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD
LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER.
THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM
IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND
ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER
THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP
CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA.
WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE
ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE
ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH
AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR
BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL
PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED.
&&
.AVIATION...05/12Z
ISSUED AT 625 AM CDT THU SEP 5 2013
WEAK SHOWER ACTIVITY WILL CONTINUE TO DRIBBLE OVER WESTERN IOWA
AND HAD HIGH ENOUGH CONFIDENCE TO LEAVE OUT ANY MENTION OF RAIN IN
THE TAFS THIS MORNING. FOD IS LIKELY TO BE THE CLOSEST BUT IF
ANYTHING DOES MAKE IT THAT FAR EAST IT WILL QUICKLY DISSIPATE WITH
THE DEEP DRY LAYER BELOW 10KFT. OTHERWISE...VFR CONDITIONS ARE
FORECAST THROUGH FRIDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...SMALL
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
356 AM CDT THU SEP 5 2013
.SHORT TERM.../TODAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
WEAK ELEVATED SHOWER ACTIVITY LOOKS TO CONTINUE THROUGH THE MID
MORNING HOURS OVER THE WESTERN EDGES OF THE FORECAST AREA. THE
WEAK AREA OF VORTICITY ADVECTION BETWEEN 700-300MB WILL DISSIPATE
BY AROUND 18Z. SOUNDINGS BELOW 10KFT REMAIN VERY DRY AND NOT
EXPECTING MUCH QPF...IF ANY AT ALL...WITH THESE SHOWERS. KEPT
THUNDER OUT OF THE FORECAST ATTM AS LITTLE TO NO INSTABILITY
PRESENT THIS MORNING. THE 09.05 05Z HRRR HAS A DECENT HANDLE ON
THE OVERALL RADAR TRENDS THIS MORNING...BUT HAS SHOWERS LINGERING
PAST 18Z. FELT CONFIDENT ENOUGH TO KEEP FORECAST DRY AFTER 16Z
THIS MORNING WITH THE LACK OF FORCING AND MOISTURE AVAILABLE. USED
A BLEND OF THE 09.05 00Z NAM12/ECMWF FOR MAX TEMPS TODAY EVEN WITH
THE MID TO HIGH LEVEL CLOUD COVER THIS MORNING.
.LONG TERM.../TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 355 AM CDT THU SEP 5 2013
MAIN CONCERNS THROUGH EARLY NEXT WEEK CONTINUE TO BE SUBTLE MINIMAL
PRECIP CHANCES AND WARMER TEMPS THROUGH EARLY NEXT WEEK. IA WILL
REMAIN IN NW FLOW INTO FRI WITH LOW CONFIDENCE IN PRECIP TRENDS.
MODELS CONTINUE TO GENERATE SPOTTY QPF BUT CANNOT REALLY FIND ANY
SUBSTANTIAL KINEMATIC OR THERMODYNAMIC FEATURES TO KEY ON...SO WITH
SURFACE BASED POTENTIAL NIL...WILL LEAVE FORECAST DRY. COULD BE
SOME WEAK VERY ELEVATED CONVECTION...BUT CONFIDENCE IN TIMING AND
LOCATION IS NOT GREAT ENOUGH TO MENTION. WARM ADVECTION DOES LIFT
THROUGH FRI DURING THE DAY...BUT MOISTURE SEEMS SOMEWHAT LIMITED AND
ITS DAYTIME TIMING WOULD NOT BE CLIMATOLOGICALLY FAVORED. HAVE
WAITED TO INTRODUCE SLIGHTS NE FRI NIGHT WHEN MOISTURE INCREASES A
BIT.
THE BIGGEST SENSIBLE WEATHER REFLECTION MAY BE TEMPERATURES WARMING
FURTHER HOWEVER WITH WIDESPREAD HIGHS ABOVE 90F. A WEAK BOUNDARY
WILL SAG INTO NRN IA SAT...BUT WILL NOT CHANGE THE AIRMASS MUCH
KEEPING TEMPS FAIRLY STATIC NORTH AND EVEN WARMING A FEW DEGREES TO
ITS SOUTH WITH PLENTY OF HIGHS IN THE MID 90S I80 INTO MO.
BAROCLINIC ZONE STRENGTHENS SLIGHTLY SAT NIGHT AS FRONT CONTINUES
TO DRIFT FARTHER SOUTH SO HAVE PUSHED FRI NIGHT SLIGHTS DOWN INTO
CENTRAL AND SRN IA BY THAT TIME. ANYTHING IN THIS TIME RANGE WOULD
LIKELY BE QUITE ELEVATED ABOVE THE ELEVATED MIXED LAYER.
THETA-E/WARM ADVECTION STRENGTHENS CONSIDERABLY BY LATE SUN FROM
IA/MN BORDER INTO THE NRN PLAINS. THIS WILL ALLOW TEMPS TO REBOUND
ONCE AGAIN AFTER BRIEFLY DROPPING A TAD SUN. THE STRONGER
THERMODYNAMIC FORCING ALSO STILL SUPPORTS MAINLY NOCTURNAL PRECIP
CHANCES NORTH...WITH BEST POTENTIAL NORTH OF IA.
WAVE CURRENTLY OFF THE OR COAST VERY SLOWLY BUT SURELY TOPS THE
ROCKIES RIDGE BY EARLY NEXT WEEK AND EVENTUALLY RESULTS IN MORE
ORGANIZED SYNOPTIC SCALE FORCING. THIS LIFT WILL SLOWLY PUSH SOUTH
AND EAST COINCIDENT WITH THE FRONTAL BOUNDARY AND LIKELY BRING OUR
BEST WINDOW OF PRECIP CHANCES LATE TUE INTO WED. THE FRONTAL
PASSAGE WILL ALSO DROP OUR TEMPS BACK CLOSER TO NORMAL FOR WED.
&&
.AVIATION...05/06Z
ISSUED AT 1202 AM CDT THU SEP 5 2013
VFR CONDITIONS EXPECTED THROUGHOUT THE TAF FORECAST PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...SMALL
AVIATION...BEERENDS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
317 PM CDT Thu Sep 5 2013
.SHORT TERM...(This Evening through Friday)
Issued at 243 PM CDT THU SEP 5 2013
Upper level high remains centered over Colorado through tomorrow
while a surface high continues to retreat eastward. An area of
isolated showers has continued to move closer to our northern
areas...although most of the precip is not reaching the ground. The
12z NAM supports moisture convergence in this area along with an
axis of slight elevated instability which extends into northeast
Kansas. The HRRR has also been consistent with bringing these
showers into our area. If showers are able to persist within the dry
air and weak advection only northern row of counties look to be
affected the next few hours with an overall diminishing trend
towards the evening.
High temperatures look to reach the low to mid 90s today which is
above normal for this time of year. The skies will remain partly
cloudy especially across northern areas closer to the ongoing shower
activity. Tonight WAA will again set up across eastern Nebraska well
north of the northeast Kansas to keep the entire area dry. Low
temperatures tonight appear to be on track for the mid to upper 60s.
Low level winds will gradually veer allowing warming 850 temps to
spread into eastern KS therefore high temperatures will make it into
the low to mid 90s again tomorrow. With more mixing likely tomorrow
during the day winds will likely increase to around 10 mph with
gusts up to 20 mph possible.
.LONG TERM...(Friday Night through Thursday)
Issued at 243 PM CDT THU SEP 5 2013
The forecast for Friday night through Tuesday is essentially one
of persistence. Other than subtle day to day differences, the
weather pattern will be fairly stagnant through the period with a
large area of upper level high pressure slowly drifting from west
to east across the plains and into the Ohio valley. High
temperatures will be consistently in the 90s. The hottest day
currently appears to be Saturday with southwest surface winds, the
upper ridge almost directly overhead, and the warmest 850 temps of
the week in place all pointing to highs in the middle to upper
90s. There will be a couple of very weak upper disturbances that
may provide enough lift for a shower or thunderstorm, mainly
northeast of the local forecast area along a weak convergence
zone, late on Saturday. Will watch these features in future
forecasts but expect dry conditions for the most part through the
weekend.
There are a couple of stronger northern stream short wave troughs
that come over the top of the ridge next week. The trough crossing
the Dakotas on Monday will push a cold front to the south, but
expect this front to lose its forward progression and stall over
northern Nebraska. The second of the stronger troughs will cross
the Dakotas late Tuesday and should successfully push the cold
front through the forecast area by late Wednesday. Much of the
upper forcing will remain well to the north, and surface
convergence is not expected to be particularly strong, but may be
sufficient for scattered storms along the incoming front. Cooler
and drier air with almost meridional flow aloft will follow the
frontal passage and expect the end of next week to be both cooler
and dry.
&&
.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 1233 PM CDT THU SEP 5 2013
VFR conditions are expected through the taf period. Winds will
remain under 10 kts and gradually veer to the south through the
period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Sanders
LONG TERM...Barjenbruch
AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS TOPEKA KS
134 PM CDT Thu Sep 5 2013
.UPDATE...
Issued at 120 PM CDT THU SEP 5 2013
An area of showers with isolated thunder has continued to develop
across south central Nebraska. The 12z NAM shows that there has
been moisture convergence in this area along with an axis of
slight elevated instability which extends into northeast Kansas.
The HRRR has also been consistent with bringing these showers into
our area. These showers only look to affect the row of counties
along the NE/KS state line during the afternoon hours.
Therefore...have increased the pops and mentioned isolated
showers and thunder until 7pm this evening in the latest forecast
update.
&&
.SHORT TERM...(Today and Tonight)
Issued at 301 AM CDT THU SEP 5 2013
Upper level pattern remains nearly locked in place with upper
high centered over the Rockies and modest but widespread 500mb
height rises across the bulk of the CONUS. Mid levels again
showing a stronger though still not impressive temperature
gradient across Nebraska from west to east, with much drier
conditions to the south. Diurnal upswing in isolated to scattered
convection again taking place in eastern Nebraska in recent hours.
Moisture is a bit richer than that of Wednesday morning, but
again support for continued precipitation this far downstream
diminishes quickly. Anything more than very isolated coverage of
measurable precip seems unlikely. Higher level cloud to again
spread across eastern Kansas today with low levels continuing to
warm a bit and should support highs a bit above Wednesday`s
levels. Mid level WAA regime sets up again to the north tonight,
though not quite as robust as current conditions and will keep
any precip mention out.
.LONG TERM...(Friday through Wednesday)
Issued at 301 AM CDT THU SEP 5 2013
As the upper ridge advances eastward, so does the warmup that
comes along with it. 850mb temps in the 21-24C range rise to 22-26
Saturday into Sunday with the warmest west and north. Strong push
of cold air dropping into the Great Lakes comes toward the
forecast area from the east by Sunday morning, but think warm air
in place and strength of the ridging will keep precip chances east
of our area. A hot late week into weekend with highs in the middle
90s quite common across the entire area.
Start to see a pattern shift into next week as the upper trof over
the west coast rides across the northern periphery of the ridge on
Monday. This sets up a front across the northern plains, and speed
to which it can advance to the south will impact temperature and
precipitation forecasts for mid week. At this time, Monday looks
to remain warm as the thermal ridge is driven to flatten to more
of a SW to NE orientation and leaves warm temperatures over the
state, and would bring another day with highs well into the 90s.
Would expect similar conditions Tuesday as front knocks on the KS
NE border by late Tuesday afternoon. EC showing better signs of a
break in the hot pattern, along with the GFS, and now has a
stronger shortwave trof dropping southward across the Rockies and
reinforces a southern push for the front. Boundary would come
through sometime on Wednesday and finally have cooler highs
forecast and precip chances in the forecast.
&&
.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 1233 PM CDT THU SEP 5 2013
VFR conditions are expected through the taf period. Winds will
remain under 10 kts and gradually veer to the south through the
period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Sanders
SHORT TERM...65
LONG TERM...67
AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1135 AM MDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1133 AM MDT THU SEP 5 2013
VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. GUSTS TO NEAR 20
KNOTS THIS AFTERNOON WILL END NEAR SUNSET.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
522 AM MDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 511 AM MDT THU SEP 5 2013
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. UPPER LEVEL
HIGH PRESSURE CENTERED OVER EASTERN COLORADO/WESTERN KANSAS WILL
BRING MOSTLY CLEAR CONDITIONS...WITH A FEW HIGH CLOUDS OVER BOTH
TAF SITES. LIGHT SOUTHERLY WINDS THIS MORNING WILL INCREASE TO
AROUND 10 TO 15 KTS MID-DAY FOR BOTH SITES AS MIXING TAKES
PLACE...WITH WIND GUSTS AROUND 20 TO 25 KTS. GUSTS SHOULD DECREASE
AROUND SUNSET WITH SUSTAINED WINDS AROUND 10KTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...ALW
AREA FORECAST DISCUSSION
NWS GOODLAND KS
520 AM MDT THU SEP 5 2013
.UPDATE...
ISSUED AT 517 AM MDT THU SEP 5 2013
REMOVED POPS/THUNDERSTORMS FROM NORTHERN TIER OF COUNTIES FOR
EARLY THIS MORNING. CONVECTION THAT WAS PERSISTENT OVERNIGHT
ACROSS EXTREME NORTHEAST COLORADO AND PARTS OF SOUTHWEST NEBRASKA
HAS FINALLY DISSIPATED.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1121 PM MDT WED SEP 4 2013
VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24
HOURS AS A RIDGE OF HIGH PRESSURE IS CENTERED OVER THE AREA. SOME
GUSTY SOUTH WIND WILL BE POSSIBLE THURSDAY IN RESPONSE TO A
SURFACE TROUGH NEAR THE KANSAS/COLORADO BORDER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...DLF
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...FS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
255 AM MDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 250 AM MDT THU SEP 5 2013
STUBBORN UPPER HIGH WILL REMAIN PARKED OVER THE FORECAST AREA
THROUGH SATURDAY...AFTER WHICH TIME THE UPPER LOW OVER THE PAC NW
WILL BEGIN TO NUDGE IT EAST. AT THE SURFACE THE WEAK TROUGH OVER
EASTERN COLORADO WILL REMAIN IN PLACE RESULTING IN SOUTHERLY
SURFACE FLOW.
NO CHANGES WORTH NOTING FROM PREVIOUS FORECAST IN TERMS OF MAX-MIN
TEMPS AND WINDS. HIGHS WILL CONTINUE IN THE 95-102 RANGE WITH LOWS
IN THE 60S. NO PRECIP IS EXPECTED DURING PERIOD AFTER THIS
MORNING. DID INCLUDE SLIGHT CHANCE POPS FROM YUMA COUNTY EAST TO
RED WILLOW FOR EARLY THIS MORNING TO ACCOUNT FOR CURRENT RADAR
TRENDS. EVEN THOUGH SHOWERS CONTINUE TO WEAKEN JUST TO OUR NORTH
OVER PHILLIPS AND CHASE COUNTIES...WILL KEEP LOW POPS GOING FOR A
FEW HOURS AFTER SUNRISE. LAST SEVERAL RUNS OF HRRR SUGGEST SOME
PRECIP MAY LINGER A BIT INTO THE MORNING HOURS. OTHERWISE...TODAY
THROUGH SATURDAY WILL BASICALLY BE A REPEAT OF YESTERDAY.
.LONG TERM...(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 250 AM MDT THU SEP 5 2013
THE 500MB HIGH IS STILL CENTERED OVER KANSAS AND BEGINS TO MOVE
EAST SUNDAY NIGHT INTO MONDAY WHILE THE UPPER LOW/TROUGH OVER THE
PACIFIC NORTHWEST MOVES INTO THE NORTHERN PLAINS. SUNDAY THROUGH
MONDAY SHOULD REMAIN WARM AND DRY...WITH HIGHS IN THE MID TO UPPER
90S. MODELS STILL DISAGREE OVER TIMING AND PLACEMENT OF THE COLD
FROPA NEXT WEEK...GFS HAS IT MOVING THROUGH MORE QUICKLY ON MONDAY
NIGHT INTO TUESDAY WHILE THE ECMWF HAS IT MOVING THROUGH TUESDAY
INTO TUESDAY NIGHT. AS OF RIGHT NOW...WEDNESDAY LOOKS TO BE THE
COOLEST DAY WITH NEAR NORMAL HIGH TEMPERATURES IN THE LOW TO MID
80S. TEMPERATURES MAY NEED ADJUSTING AS THE WEEK PROGRESSES AND
THE TIMING/PLACEMENT OF THE FRONT IS MORE SOLID. THE ALLBLEND
SOLUTION FOR TEMPERATURES AND PRECIPITATION SEEMED LIKE THE BEST
WITH THE CURRENT MODEL DIFFERENCES. THERE WERE MINOR ADJUSTMENTS
TO PRECIP...REMOVING THE 15 POP IN EASTERN COLORADO ON MONDAY
AFTERNOON CONSIDERING THE RIDGE WILL STILL BE IN PLACE...AND THERE
IS NO FEATURE THAT WOULD INDICATE PRECIP. OTHER THAN THAT...PRECIP
CHANCES ARE STILL THE GREATEST IN THE MONDAY NIGHT THROUGH
WEDNESDAY TIME FRAME. GFS HAS PWATS AROUND 1.50 ON TUESDAY
WHICH...GIVEN THE FRONT MOVING THROUGH AND NORTHEASTERLY/EASTERLY
FLOW BEHIND THE FRONT...COULD RESULT IN SOME GOOD RAINFALL AMOUNTS
WITH THE SHOWERS AND THUNDERSTORMS THAT MOVE THROUGH THE CWA.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1121 PM MDT WED SEP 4 2013
VFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK FOR THE NEXT 24
HOURS AS A RIDGE OF HIGH PRESSURE IS CENTERED OVER THE AREA. SOME
GUSTY SOUTH WIND WILL BE POSSIBLE THURSDAY IN RESPONSE TO A
SURFACE TROUGH NEAR THE KANSAS/COLORADO BORDER.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DLF
LONG TERM...ALW
AVIATION...FS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
411 PM EDT THU SEP 5 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 410 PM EDT THU SEP 5 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW
THROUGH THE GREAT LAKES BETWEEN A TROUGH OVER NE CANADA AND A RIDGE
FROM COLORADO INTO THE WRN PLAINS. THE MAIN UPSTREAM SHORTWAVE
TROUGH OF INTEREST WAS MOVING INTO WEST CENTRAL SASK. AT THE
SFC...HIGH PRES WAS CENTERED OVER MI AND THE WRN GREAT LAKES
BRINGING CLEAR SKIES AND LIGHT WINDS TO THE REGION.
TONIGHT...MAINLY CLEAR SKIES THIS EVENING ARE EXPECTED TO GIVE WAY
TO INCREASING MID/HIGH CLOUDS LATE. TEMPS MAY DROP OFF QUICKLY AFTER
SUNSET BUT WITH INCREASING SW FLOW OVERNIGHT...TEMPS ARE EXPECTED TO
ONLY DROP TO AROUND CENTRAL 50 AND BECOME STEADY OR SLOWLY RISING IN
THE MID TO UPPER 50S WEST.
FRIDAY...THE SASK SHRTWV IS EXPECTED TO SLIDE JUST NORTH OF LAKE
SUPERIOR. HOWEVER...925-700 MB THETA-E ADVECTION AHEAD OF THIS
FEATURE AND ASSOCIATED 310K ISENTROPIC LIFT WILL SUPPORT SCT ELEVATED
SHRA/TSRA INTO N AND W LAKE SUPERIOR BY LATE MORNING THAT MAY SPREAD
INTO THE CNTRL AND EAST DURING THE AFTERNOON. THERE IS STILL ENOUGH
UNCERTAINTY WITH MDLS DIFFERING ON TIMING/POSITION OF THE PCPN TO
KEEP JUST CHANCE POPS. ALTHOUGH MUCAPE VALUES TO AROUND 1K J/KG
RANGE MAY SUPPORT SOME STRONGER STORMS...THE GREATER INSTABILITY
WITH MLCAPES OF 1000-1500 J/KG IS EXPECTED TO REMAIN UPSTREAM OVER
MN. EVEN WITH INCREASING CLOUDS AND PCPN POSSIBLE DURING THE
AFTERNOON...HIGH TEMPS SHOULD CLIMB INTO THE LOWER 80S.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 410 PM EDT THU SEP 5 2013
MAIN FCST CONCERNS IN THE LONGER TERM REVOLVE ARND POPS ON FRI
NGT/SAT ASSOCIATED WITH PASSAGE OF SHRTWVS IN NW FLOW ALF BTWN THE
MEAN TROF OVER QUEBEC AND RIDGE IN THE PLAINS. FOCUS FOR LATER IN
THE WEEKEND TURNS TOWARD HI PRES BLDG INTO THE UPR LKS.
FRI NGT/SAT...A SHRTWV EMBEDDED IN THE NW FLOW ALF IS PROGGED TO
PASS NEAR THE UPR LKS IN THE EVNG...SO EXPECT THE BEST CHC OF
SHRA/TS TO BE IN THE EVNG WHEN ACCOMPANYING PVA INTERACTS WITH AXIS
OF HIER H85 THETA E. MID LVL DRYING/NEGATIVE H85 THETA E AVCTN IN
THE WAKE OF THIS INITIAL SHRTWV PASSAGE WL THEN RESULT IN
DIMINISHING POPS NW-SE THRU SAT MRNG...BUT APRCH OF ANOTHER SHRTWV
IN THE NW FLOW ALF WARRANTS AT LEAST A SCHC OF LINGERING SHRA. THE
12Z GFS AND ESPECIALLY THE 00Z CNDN MODELS ARE SLOWER/STRONGER THAN
THE BULK OF THE OTHER GUIDANCE WITH THIS TRAILING
DISTURBANCE...LINGERING DEEP LYR QVECTOR CNVGC AND QPF THRU MOST OF
THE DAY ON SAT...SO RETAINED SOME LO CHC POPS ESPECIALLY OVER THE
SCENTRAL THRU THE ENTIRE DAY.
SAT NGT THRU SUN...CNDN HI PRES UNDER CONFLUENT NW FLOW ALF BTWN THE
TROF IN QUEBEC/RDG IN THE PLAINS IS PROGGED TO SHIFT FM MANITOBA AT
00Z SUN TO OVER LK SUP SUN AFTN. UNDER LARGER SCALE SUBSIDENCE AND
PWAT FCST AOB 0.50 INCH...DRY WX WL PREVAIL. THE ONLY CONCERN IS
WHETHER THERE WL BE ANY LO CLDS AT LEAST FOR A TIME NEAR LK SUP WITH
UPSLOPE NNE FLOW UNDER SHARP SUBSIDENCE INVRN H85-9 IN ADVANCE OF
THE INCOMING SFC HI AS SUGGESTED BY THE 06Z AND 12Z GFS RUNS. GIVEN
LARGE SCALE ACYC LLVL FLOW...DRY NATURE OF INCOMING AIRMASS AND
MARGINAL CHILL OF THIS AIRMASS FOR LK CLDS /H925 TEMPS NO LOWER THAN
6-7C OVER THE E HALF COMPARED TO OPEN WATER TEMPS 14-15C/...
RESTRICTED FCST OF SCT-BKN LO CLDS TO THE HIER TERRAIN OF THE
NCENTRAL EARLY SUN MRNG PER THE MORE PESSIMISTIC GFS FCST SDNGS AND
BEFORE DAYTIME HEATING WOULD MIX THESE CLDS OUT ON SUN AFTN. TEMPS
ON SUN MRNG/AFTN WL BE COOLER THAN THE DAY BEFORE WITH H85 TEMPS
FCST BTWN 5-10C DURING THIS PERIOD. EXPECT THE LOWEST MIN TEMPS ON
SUN MRNG OVER THE INTERIOR W...WITH NNE FLOW OFF LK SUP KEEPING
AREAS NEAR THE SHORE WARMER.
SUN NGT...AS SFC HI PRES DRIFTS OVER NY STATE BY 12Z SUN...A RETURN
SLY FLOW OF WARMER/MOISTER AIR BTWN THIS FEATURE AND A SHRTWV/
ACCOMPANYING SFC LO MOVING INTO THE NRN PLAINS WL DVLP OVER THE UPR
LKS. SO EXPECT AT LEAST SOME INCRS IN CLDS AND A WARMER OVERNGT.
RESTRICTED POPS TO THE FAR WRN CWA GIVEN MODEL QPF/LINGERING LLVL
DRY AIR OVER MOST OF THE CWA.
MON INTO TUE...AS SHRTWV IN THE NRN PLAINS AND ATTENDANT SFC LO PRES/
WARM FNT MOVE TOWARD THE UPR LKS...EXPECT SHRA/TS CHCS TO INCRS OVER
THE CWA. NOT SURPRISINGLY...THE EXTENDED MODELS DISAGREE ON THE
EXACT TRACK OF THE SFC LO/WARM FNT AND AXIS OF HIER QPF. THE 12Z AND
ESPECIALLY THE 00Z CNDN MODELS ARE FARTHER N WITH THE SFC LO TRACK/
WARM FNT AND FCSTS THE BULK OF ANY ACCOMPANYING SHRA/TS TO REMAIN N
OF UPR MI WHILE THE 06Z GFS FCSTS HEAVY PCPN WITH THE SFC LO
TRACKING E THRU THE CWA OVER THE WARM FNT ON MON INTO EARLY TUE. THE
RESULT OF THIS SCENARIO WOULD BE A WARM SUMMER-LIKE DAY WITH A GOOD
DEAL OF SUNSHINE AND H85/SFC TEMPS NEAR 20C/WELL INTO THE 80S AWAY
FM LK MODERATION IN LLVL SW FLOW. SHRA/TS WITH HEAVY RA/PSBL SEVERE
TS WOULD BE THE RESULT IF THE GFS MODEL VERIFIES. THE 12Z GFS/00Z
ECWMF RUNS ARE A COMPROMISE BTWN THOSE TWO CAMPS AND ALSO INDICATE
THE POTENTIAL FOR SEVERE TS WITH FCST H85 TEMPS UP TO 20C AND SSI AS
LO AS -3 TO -4C UNDER STRONGER H5 FLOW. GIVEN THESE UNCERTAINTIES...
MAINTAINED CONSENSUS FCST FOR NOW.
EXTENDED...AS AN UPR TROF DEEPENS INTO THE GREAT LKS ON WED BEHIND
DEPARTING SHRTWV RESPONSIBLE FOR THE MON/TUE POPS...EXPECT SHRA/TS
CHCS TO PERSIST. EXPECT COOLER/DRIER WX TO SPREAD TO THE E NEXT
THU/FRI AS HI PRES BLDS TOWARD THE PLAINS/WRN GRT LKS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 131 PM EDT THU SEP 5 2013
WITH HIGH PRESSURE OVER THE REGION...EXPECT VFR CONDITIONS AND LIGHT
WINDS THROUGH MOST OF TONIGHT. MID CLOUDS WILL BEGIN TO THICKEN
AFTER MIDNIGHT AT CMX...BUT ANY SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO HOLD OFF UNTIL FRIDAY AFTERNOON. CONFIDENCE IN THE
SHA/TSRA ARRIVAL TIME AND PROBABILITY WAS LOW SO NONE MENTIONED
THROUGH 18Z/FRI.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 410 PM EDT THU SEP 5 2013
EXPECT SW WINDS UP TO 20-25 KTS ON FRI UNDER SHARPENING PRES
GRADIENT AHEAD OF INCOMING LO PRES TROUGH. FOLLOWING THE PASSAGE OF
A COLD FRONT ON SAT...WINDS WILL VEER TO THE N-NE AND REMAIN UP TO
20 KTS INTO SUN IN ADVANCE OF HI PRES BUILDING TOWARD THE GREAT
LAKES. A RELATIVELY WEAK PRES GRADIENT AND/OR HI OVERWATER STABILITY
WILL THEN DOMINATE ON SUN INTO TUE...RESULTING IN WINDS UNDER 20 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
147 AM EDT THU SEP 5 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 407 PM EDT WED SEP 4 2013
WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL THROUGH THE
UPPER GREAT LAKES BETWEEN A LOW OVER NRN QUEBEC AND A RIDGE FROM
COLORADO THROUGH THE WRN PLAINS. WITH CONFLUENT FLOW AND 700-300 MB
QVECTOR DIV BUILDING INTO THE AREA...EXPECT MAINLY CLEAR SKIES TO
PREVAIL WITH ONLY SOME BANDS OF CIRRUS THROUGH THE ERN CWA...PER VIS
IMAGERY. AT THE SFC...HIGH PRES FROM SRN MANITOBA INTO NW ONTARIO
WAS BUILDING INTO THE NRN GREAT LAKES WITH INFLUX OF DRY AIR ON NRN
ACYC FLOW. LOWER DEWPOINTS UPSTREAM FROM LAKE SUPERIOR (READINGS IN
THE UPPER 30S) WERE FILTERING TOWARD UPPER MI.
TONIGHT...EVEN WITH PWAT VALUES AROUND 0.50 INCH CLIMBING TO NEAR
0.75 INCH...WITH HIGH PRES BUILDING INTO UPPER MI...MOSTLY CLEAR
SKIES AND LIGHT WINDS ALLOW TEMPS TO DROP OFF TOWARD THE LOWER END
OF GUIDANCE. READINGS INTO THE UPPER 30S INLAND WEST AND LOW TO MID
40S OVER THE EAST AND ALONG THE GREAT LAKES ARE EXPECTED. PATCHY
FROST MAY BE POSSIBLE IN THE TYPICAL COLD SPOTS FROM REPUBLIC AND
CHAMPION TO AMASA...IRON RIVER AND WATERSMEET.
THURSDAY...UNDER ABUNDANT SUNSHINE WITH 850 MB TEMPS IN THE 6C TO
10C RANGE...TEMPS WILL REBOUND CLOSER TO SEASONAL AVERAGES WITH HIGHS
RANGING FROM THE UPPER 60S EAST TO THE LOWER 70S WEST.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 407 PM EDT WED SEP 4 2013
HIGH PRESSURE WILL KEEP WEATHER QUIET THURSDAY NIGHT THROUGH EARLY
FRIDAY AFTERNOON. AS THE HIGH CENTERS OVER THE EASTERN
SEABOARD...UPPER MICHIGAN IS POSITIONED ON THE NORTHWESTERN
PERIPHERY OF THE RIDGE...MAKING US VULNERABLE FOR WEAK WAVES TO
SLIDE THROUGH. THE FIRST OF THESE SLIDES OUT AHEAD OF THE MAIN
TROUGH ON FRIDAY AFTERNOON. MODELS ARE MOSTLY IN AGREEMENT...WITH
THE EXCEPTION OF THE GFS WHICH BRINGS THE MAIN TROUGH IN MUCH
QUICKER...SO STRAYED FROM THAT SOLUTION. USED PRIMARILY THE
GEM/ECMWF FOR THIS LONG TERM FORECAST.
WEAK MOISTURE ADVECTION/CONVERGENCE SHOWS UP FOR THE MID LEVELS AND
FOCUSES ACROSS THE WEST AND NORTHERN PORTIONS OF THE CWA EARLIER IN
THE DAY...PRIMARILY OVER THE KEWEENAW AND LAKE SUPERIOR. THROUGHOUT
THE DAY THIS REGION MOVES EAST-SOUTHEASTWARD TOWARDS QUEBEC...SO
KEPT PCP CHANCES FAR EAST INTO FRIDAY EVENING. OVERALL...850-500MB
QVECTOR CONVERGENCE IS PALTRY BUT WARRANTS SOME SLIGHT CHANCE/CHANCE
POPS. LOW LEVELS ARE FAIRLY DRY THOUGH...AND INSTABILITY IS MINIMAL.
WILL KEEP THE POPS PRIMARILY OVER THE LAKE AND FAR EAST FOR NOW.
FRIDAY NIGHT THROUGH SATURDAY THE STRONGER TROUGH MOVES THROUGH THE
GREAT LAKES AS LOW PRESSURE OVER JAMES BAY ON FRIDAY MOVES INTO
QUEBEC. MOISTURE IS DEEPER AND INSTABILITY IS GREATER THIS GO
AROUND...WHICH WILL SUPPORT SHOWERS AND TSTORMS ACROSS THE CWA. THE
WESTERN CWA IS LIKELY TO SEE SHOWERS/A FEW TSTORMS STARTING LATER
FRIDAY NIGHT AND CONTINUING THROUGH MAINLY SATURDAY MORNING. WITH
GREATER INSTABILITY BUILDING TOWARDS SATURDAY AFTERNOON ALONG THE WI
BORDER AND CENTRAL U.P. LINGERED CHANCE POPS THERE THROUGH THE
AFTERNOON.
THE BEST MOISTURE IS CENTRAL AND EAST HOWEVER...AND SFC BASED CAPE
IS AROUND 1000-500 J/KG FOR THE AFTERNOON. WITH THE FRONT PASSING
THROUGH THE CENTRAL CWA AROUND 18Z AND NORTHWEST FLOW ALOFT...EXPECT
WE WILL SEE SOME ACTIVITY. 0-6KM BULK SHEAR IS AROUND 20-30
KNOTS...SO DO NOT EXPECT ANYTHING TOO GET TOO ORGANIZED. ANY SEVERE
THREAT AS OF RIGHT NOW LOOKS TO BE VERY ISOLATED.
ON SUNDAY HIGH PRESSURE BRINGS A BRIEF BREAK TO THE PRECIPITATION.
MONDAY AND TUESDAY A WARM FRONT LIFTS ACROSS THE MIDWEST WITH A
STRONGER LOW PRESSURE SYSTEM IN THE NORTHERN PLAINS. THIS LOW WILL
MOVE NORTHEASTWARD INTO ONTARIO...AND EVENTUALLY BRING A COLD FRONT
ACROSS UPPER MI ON WEDNESDAY. HAVE CHANCE POPS IN THE FORECAST FOR
NOW...GIVEN DIFFERENCES BETWEEN MODELS IN THE LOCATION OF THE LOW
PRESSURE SYSTEM DURING THESE TIMES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 144 AM EDT THU SEP 5 2013
WITH HIGH PRESSURE BUILDING INTO THE REGION...EXPECT VFR CONDITIONS
AND LIGHT WINDS THROUGH THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 407 PM EDT WED SEP 4 2013
WITH HIGH PRES BUILDING INTO THE UPPER LAKES...WINDS WILL DIMINISH
TO LESS THAN 20 KTS LATER TONIGHT INTO THURSDAY. SW WINDS WILL
INCREASE ON FRIDAY IN THE TIGHTER PRESSURE GRADIENT BETWEEN THE
EXITING HIGH PRESSURE AND A COLD FRONT THAT ARRIVES THIS WEEKEND.
EXPECT WINDS ON FRIDAY TO STAY LESS THAN 25 KTS. WINDS FOR THE
REMAINDER OF THE FORECAST PERIOD WILL REMAIN LESS THAN 20 KNOTS DUE
TO WEAKER PRESSURE GRADIENT.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...MCD
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1236 PM CDT Thu Sep 5 2013
.SHORT TERM...(Today through Saturday)
Issued at 410 AM CDT THU SEP 5 2013
At 8z water vapor imagery and RAP analysis continue to indicate a
strong 596 hpa H5 ridge over the interior mountain region of the
CONUS, with a deep trough over the Hudson Bay area. Between these
two features light northwest flow continues in the mid levels. At 8z
water vapor as well as IR imagery indicated an area of mid level
clouds rounding the northwest quadrant of the mid level ridge across
far eastern Nebraska and far western Iowa. Radar imagery indicates
that there are a few showers associated with this area of clouds.
These showers, with an isolated lightning strike or two are likely
associated with a very weak and subtle impulse rounding the mid
level ridge. Today`s forecast will depend on how many clouds this
subtle wave will form through the day. The current thought is that
these showers will likely not make it as far south as Interstate 70,
although a few light sprinkles or showers may affect the far
northern and western portions of Missouri and extreme NE Kansas. As
the trough moves through it looks as though it will bring with it
some mid level cloud cover, especially in the western half of the
forecast area. These mid level clouds could act to keep temperatures
a bit cooler than the going forecast suggested. Have gone with a dry
forecast for today, and dropped temperatures 1-3 degrees in the
western half of the CWA for day time highs. Even though perhaps
slightly cooler temps are expected day time highs will still make it
into the mid to upper 80s, but will continue to monitor the diurnal
trend and adjust based on how the cloud cover behaves.
For the rest of the mid range forecast expect dry conditions to
remain, as the mid level ridge continues to shunt any strong chance
for rain well north of the forecast area. With the steady flow of
southerly winds into the area as well as the mid level ridge keeping
the area clear of any significant cloud cover or rain expect a
steady warm up through the weekend, with daytime highs reaching the
lower 90s for Friday, and rising into the lower to mid 90s for
Saturday and Sunday. The only chance for rain in the forecast area
through the weekend will be a minimal chance for an isolated shower
or two across NC/NE Missouri Saturday night into Sunday morning.
.LONG TERM...(Sunday through Wednesday)
Issued at 410 AM CDT THU SEP 5 2013
Well above average temperatures will continue into the extended time
period however models are hinting at a potential pattern change
toward the end of the period. These well above above average
temperatures have been courtesy of an upper level ridge of high
pressure that has been dominating the regions weather. This will
also be the case at the onset of the extended period as the upper
level ridge axis will reside over the central Plains. Sunday an
upper level shortwave will be rounding this ridge and models
indicate that an overnight MCS will develop over Iowa and roll into
the eastern portion of the CWA Sunday morning. As such have added
slight chance POPs to the eastern CWA with slightly cooler
temperatures around 90 across the eastern CWA. Temperatures
elsewhere across the CWA will reach into the mid 90s.
Monday will be the warmest day in the extended time frame as the
upper level ridge axis moves directly overhead. Highs will reach
into the mid 90s CWA wide. However, Monday night an upper level
trough will move through the northern Plains into the Upper Midwest.
This will force a weak cold front towards the area however, it will
initially get hung up north of the CWA. It will also flatten the
upper level ridge across the area and force it into the southeastern
CONUS. This will make for a "cooler" Tuesday with highs in the low
to mid 90s.
Tuesday night a second upper level trough will dig into the northern
Plains. Models differ on the strength of the trough as the EC is
much stronger with it than the GFS or GEM. In either case, the
aforementioned cold front that was hung up north of the area will be
forced into the CWA Tuesday night. This will have a two-fold effect:
First, it will bring the next chance for showers and thunderstorms
to the area Tuesday night into Wednesday. Second, it will cool
temperatures into the mid to upper 80s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1235 PM CDT THU SEP 5 2013
VFR conditions look to prevail at the terminals again overnight with
the possible exception of KSTJ. Wind will likely go calm overnight,
but expect to only have surface restriction in the River Valley near
the KSTJ terminal during the early morning hours.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Leighton
LONG TERM...73
AVIATION...Cutter
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
411 AM CDT Thu Sep 5 2013
.SHORT TERM...(Today through Saturday)
Issued at 410 AM CDT THU SEP 5 2013
At 8z water vapor imagery and RAP analysis continue to indicate a
strong 596 hpa H5 ridge over the interior mountain region of the
CONUS, with a deep trough over the Hudson Bay area. Between these
two features light northwest flow continues in the mid levels. At 8z
water vapor as well as IR imagery indicated an area of mid level
clouds rounding the northwest quadrant of the mid level ridge across
far eastern Nebraska and far western Iowa. Radar imagery indicates
that there are a few showers associated with this area of clouds.
These showers, with an isolated lightning strike or two are likely
associated with a very weak and subtle impulse rounding the mid
level ridge. Today`s forecast will depend on how many clouds this
subtle wave will form through the day. The current thought is that
these showers will likely not make it as far south as Interstate 70,
although a few light sprinkles or showers may affect the far
northern and western portions of Missouri and extreme NE Kansas. As
the trough moves through it looks as though it will bring with it
some mid level cloud cover, especially in the western half of the
forecast area. These mid level clouds could act to keep temperatures
a bit cooler than the going forecast suggested. Have gone with a dry
forecast for today, and dropped temperatures 1-3 degrees in the
western half of the CWA for day time highs. Even though perhaps
slightly cooler temps are expected day time highs will still make it
into the mid to upper 80s, but will continue to monitor the diurnal
trend and adjust based on how the cloud cover behaves.
For the rest of the mid range forecast expect dry conditions to
remain, as the mid level ridge continues to shunt any strong chance
for rain well north of the forecast area. With the steady flow of
southerly winds into the area as well as the mid level ridge keeping
the area clear of any significant cloud cover or rain expect a
steady warm up through the weekend, with daytime highs reaching the
lower 90s for Friday, and rising into the lower to mid 90s for
Saturday and Sunday. The only chance for rain in the forecast area
through the weekend will be a minimal chance for an isolated shower
or two across NC/NE Missouri Saturday night into Sunday morning.
.LONG TERM...(Sunday through Wednesday)
Issued at 410 AM CDT THU SEP 5 2013
Well above average temperatures will continue into the extended time
period however models are hinting at a potential pattern change
toward the end of the period. These well above above average
temperatures have been courtesy of an upper level ridge of high
pressure that has been dominating the regions weather. This will
also be the case at the onset of the extended period as the upper
level ridge axis will reside over the central Plains. Sunday an
upper level shortwave will be rounding this ridge and models
indicate that an overnight MCS will develop over Iowa and roll into
the eastern portion of the CWA Sunday morning. As such have added
slight chance POPs to the eastern CWA with slightly cooler
temperatures around 90 across the eastern CWA. Temperatures
elsewhere across the CWA will reach into the mid 90s.
Monday will be the warmest day in the extended time frame as the
upper level ridge axis moves directly overhead. Highs will reach
into the mid 90s CWA wide. However, Monday night an upper level
trough will move through the northern Plains into the Upper Midwest.
This will force a weak cold front towards the area however, it will
initially get hung up north of the CWA. It will also flatten the
upper level ridge across the area and force it into the southeastern
CONUS. This will make for a "cooler" Tuesday with highs in the low
to mid 90s.
Tuesday night a second upper level trough will dig into the northern
Plains. Models differ on the strength of the trough as the EC is
much stronger with it than the GFS or GEM. In either case, the
aforementioned cold front that was hung up north of the area will be
forced into the CWA Tuesday night. This will have a two-fold effect:
First, it will bring the next chance for showers and thunderstorms
to the area Tuesday night into Wednesday. Second, it will cool
temperatures into the mid to upper 80s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1154 PM CDT WED SEP 4 2013
Nothing has changed from the previous discussion with VFR and light
southeast winds prevailing. KSTJ and river valleys across northern
and west central MO can expect patchy fog...with intermittent IFR
visibilities at KSTJ due to local effects...forming during the pre-
dawn hours and quickly dissipating after sunrise.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
SHORT TERM...Leighton
LONG TERM...73
AVIATION...MJ
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
622 PM CDT FRI SEP 6 2013
.SYNOPSIS...
ISSUED AT 334 PM CDT FRI SEP 6 2013
UPPER LEVEL HIGH PRESSURE...REMAINS STATIONARY OVER NERN
COLORADO ATTM WITH RIDGING EXTENDING NORTH INTO SOUTHERN
SASKATCHEWAN. LOW PRESSURE ALOFT WAS PRESENT OVER SOUTH CENTRAL
WASHINGTON STATE...WITH ANOTHER UPPER LEVEL LOW OFF THE COAST OF NRN
QUEBEC. AT THE SURFACE...LOW PRESSURE WAS PRESENT OVER SOUTH CENTRAL
SOUTH DAKOTA WITH A WEAK SURFACE TROUGH EXTENDING SSW FROM THIS
FEATURE INTO THE SRN PANHANDLE AND NERN COLORADO. WITH THE EXCEPTION
OF THE NORTHEASTERN NEBRASKA PANHANDLE...SKIES WERE MOSTLY CLEAR
WITH 3 PM CDT TEMPERATURES RANGING FROM 94 AT ONEILL TO 105 AT
IMPERIAL.
&&
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 334 PM CDT FRI SEP 6 2013
HOT THIS AFTERNOON...WITH NEAR RECORD OR RECORD HIGH TEMPERATURES
ACROSS WESTERN NEBRASKA. THE CENTER OF THE UPPER LEVEL HIGH PRESSURE
IS ACROSS SOUTHWEST NEBRASKA...AND WILL MIGRATE SLOWLY SOUTHEAST
INTO EASTERN KANSAS BY SUNDAY EVENING. AN ISOLATED THUNDERSTORM IS
POSSIBLE ACROSS NORTHWEST NEBRASKA THIS EVENING...WHERE A WEAK
DISTURBANCE WILL MIGRATE NORTHEAST AROUND THE PERIPHERY OF THE UPPER
LEVEL HIGH PRESSURE CENTER. LOWS TONIGHT WILL AGAIN BE COMFORTABLE
IN THE LOWER TO MID 60S MOST LOCALS DUE TO DRY AIR IN PLACE.
A WEAK COLD FRONT WILL DROP INTO NORTHERN NEBRASKA SATURDAY...BUT
CONTINUED SUBSIDENCE AND WARM AIR ALOFT SHOULD KEEP ANY
THUNDERSTORMS AT BAY ALONG THE FRONT. ANOTHER HOT DAY...ESPECIALLY
SOUTH OF THE FRONT ACROSS SOUTHWEST NEBRASKA...WHERE HIGHS IN THE
UPPER 90S TO 102 DEGREES ARE EXPECTED. SOMEWHAT COOLER ACROSS
NORTHERN NEBRASKA...WITH HIGHS IN THE LOWER TO MID 90S NORTH OF THE
FRONT.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 334 PM CDT FRI SEP 6 2013
SATURDAY NIGHT THROUGH MONDAY NIGHT...TEMPERATURES
SUNDAY AND MONDAY...ALONG WITH PRECIPITATION CHANCES MONDAY NIGHT
ARE THE MAIN FORECAST CHALLENGES IN THE MID RANGE PERIODS. FOR
SATURDAY NIGHT...SURFACE HIGH PRESSURE WILL TRACK FROM WESTERN
ONTARIO INTO THE NORTHERN GREAT LAKES. THE STALLED OUT FRONTAL
BOUNDARY OVER THE CENTRAL FCST AREA...WILL BEGIN TO LIFT NORTH AS A WARM
FRONT OVERNIGHT SATURDAY NIGHT INTO EARLY SUNDAY MORNING. AT THE
SAME TIME... SURFACE LOW PRESSURE...ALONG A COLD FRONT...WILL DEEPEN
ACROSS THE WESTERN NEBRASKA PANHANDLE AND EASTERN WYOMING...LEADING
TO INCREASED SOUTHERLY WINDS ACROSS WESTERN AND NORTH CENTRAL
NEBRASKA FOR SUNDAY. H85 TEMPS RANGING FROM 30 TO 33C WILL SURGE
NORTH INTO SRN SD SUNDAY AFTERNOON...LEADING TO YET ANOTHER DAY OF
90S TO NEAR TRIPLE DIGIT HEAT ACROSS THE FORECAST AREA. HIGHS WILL
RANGE FROM THE MIDDLE 90S INT THE NORTHEASTERN CWA...TO AROUND 100
IN THE SOUTHWESTERN FORECAST AREA. FOR SUNDAY THE RECORD HIGH FOR
NORTH PLATTE IS 99 DEGREES...AND THERE IS A DECENT CHANCE FOR THIS
RECORD TO BE TIED OR BROKEN. FOR SUNDAY NIGHT...TSRAS REMAIN
POSSIBLE INVOF THE STALLED OUT FRONT OVER THE NERN NEBR PANHANDLE.
MID AND UPPER LEVEL SUPPORT FOR PRECIPITATION WILL BE BEST ALONG THE
FRONTAL BOUNDARY...AND OFF TO THE WEST OVER THE CENTRAL AND NRN
ROCKIES...SO WITH THE EXCEPTION OF THE NRN PANHANDLE...A DRY FCST
CONTINUES. ON MONDAY...AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL
LIFT EAST ACROSS NERN MT INTO NRN ND...SUPPRESSING THE UPPER LEVEL
HIGH AND FORCING A COLD FRONT THROUGH WESTERN AND NORTH CENTRAL
NEBRASKA. FRONTAL TIMING IS FAIRLY CONSISTENT BETWEEN THE NAM/GFS
AND ECMWF SOLNS THIS MORNING...AS THE FRONT IS FORECAST TO CLEAR THE
AREA BY 00Z TUES. HIGHS MONDAY WILL RANGE FROM THE LOWER 80S IN THE
FAR NORTHWEST...TO THE LOWER TO MID 90S IN THE SERN ZONES. AS FOR
PCPN CHANCES IN ASSOCIATION WITH THE FRONT...DECIDED TO HOLD OFF ON
THE HIGHEST POPS UNTIL MONDAY NIGHT...WHICH IS POST FRONTAL. UPPER
LEVEL SUPPORT FOR PRECIPITATION IS DELAYED SOME INTO MONDAY EVENING
PER THE LATEST GFS AND ECMWF SOLNS...AND IS ABOUT 6 TO 12 HRS SLOWER
THAN THE NAM SOLN WHICH HAS THE BEST SUPPORT ON MONDAY
MORNING/AFTERNOON.
TUESDAY THROUGH FRIDAY...PRECIPITATION WILL LINGER IN THE SOUTH INTO
TUESDAY...AS THE FRONT PUSHES SOUTH INTO KANSAS. HOW FAR THE FRONT
TRACKS SOUTH IS STILL UP IN THE AIR AS THE GFS AND ECMWF SOLNS HAVE
DIVERGED 180 DEGREES FROM YESTERDAYS RUNS. THE GFS NOW PUSHES THE
FRONT WELL SOUTH OF THE AREA...WHILE THE ECMWF FAVORS A MORE
NORTHERN SOLN...STALLING THE FRONT ACROSS NRN KS. IN LIGHT OF THE
MODEL DIFFERENCES...DECIDED TO KEEP THE EXTENDED FCST CONSISTENT
WITH THE PREVIOUS FCST...AND KEEP THINGS DRY WITH HIGHS IN THE 80S.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 622 PM CDT FRI SEP 6 2013
THE HRRR SUGGESTS THE TSTM ACTIVITY ACROSS WRN NEB COULD LAST
UNTIL 05Z-06Z THIS EVENING. WE SHOULD SEE A VERY SLOW EASTWARD MOTION
BETWEEN 5 AND 10 MPH. THIS COULD CAUSE THE ACTIVITY TO MOVE
THROUGH KVTN. OTHERWISE VFR IS EXPECTED THROUGH 21Z SATURDAY.
THEREAFTER...WE MIGHT SEE MORE ISOLATED STORMS...ALONG A STALLED
OUT FRONT...NEAR NEBRASKA HIGHWAY 2 BUT THIS IS UNCERTAIN SINCE
ONLY THE ECM SHOWS ANYTHING FORMING AND IT SHOWS A STORM NEAR THE
SD BORDER...MUCH FARTHER NORTH.
&&
.FIRE WEATHER...
ISSUED AT 334 PM CDT FRI SEP 6 2013
A WEAK COLD FRONT WILL SLIP INTO NORTHERN NEBRASKA SATURDAY. TO THE
SOUTH OF THE FRONT...IT WILL AGAIN BE HOT AND DRY WITH HIGHS NEAR
100 AND LOW RELATIVE HUMID TY. WIND AGAIN IS EXPECTED TO BE LIGHT
ENOUGH THAT RED FLAG CONDITIONS ARE NOT EXPECTED. SUNDAY COULD BE A
DIFFERENT STORY AS TEMPERATURES REMAIN HOT...AND WINDS INCREASE SOME
FROM THE SOUTH AND HUMIDITY REMAINS LOW. CONDITIONS SHOULD IMPROVE
MONDAY WITH HIGHER HUMIDITY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CLB
SHORT TERM...TAYLOR
LONG TERM...CLB
AVIATION...CDC
FIRE WEATHER...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
403 AM CDT THU SEP 5 2013
.SYNOPSIS...
ISSUED AT 400 AM CDT THU SEP 5 2013
HUDSON BAY HAS DEEPENED CONSIDERABLY OVER THE PAST 24 HOURS WITH
A TROUGH EXTENDING DOWN THE ATLANTIC SEABOARD. HEAT RIDGE
CENTERED OVER NORTHEAST COLORADO HOLDS WITH A SHARP RIDGE INTO
THE CENTRAL PLAINS OF CANADA. CLOSED LOW OFF THE OREGON COAST
NEARLY STATIONARY OVER THE PAST 24 HOURS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CDT THU SEP 5 2013
MODELS FAIRLY CONSISTENT IN THE NEAR TERM. RING OF FIRE WITH THE
UPPER LOW CENTERED OVER NORTHEAST COLORADO AND WESTERN NEBRASKA
POSITIONED FOR WEAK WAVES MOVING THROUGH QUICKLY AND SETTING OFF
MAINLY ISOLATED THUNDERSTORMS. WILL CARRY A PRE FIRST PERIOD IN
THE ZONES TO ACCOUNT FOR ONGOING PRECIPITATION. ISO T MOVING OUT
OF THE FORECAST AREA EARLY THIS MORNING. DEBRIS CLOUDS MAY BE
HARD TO GET RID OF TODAY. WITH THIS IN MIND HAVE UNDERCUT
GUIDANCE BY A COUPLE OF DEGREES AND KEPT NORTH CENTRAL NEBRASKA
COOLER BUT THE SOUTHWEST AND THE EASTERN NEBRASKA PANHANDLE IN
THE VICINITY OF THE SURFACE TROUGH WILL SEE TEMPERATURES SOAR TO
AROUND 100 DEGREES. STRONG SOUTHEAST FLOW TODAY TO THE EAST OF
THE SURFACE TROUGH OVER THE NEBRASKA PANHANDLE. WILL SEE ISOLATED
THUNDERSTORMS AGAIN IN THE PANHANDLE THIS AFTERNOON AND EVENING
BUT SHOULD NOT MAKE IT TOO FAR OFF THE HIGHER TERRAIN AND HAVE
ENDED THROUGH THE EVENING. A WARM NIGHT AGAIN WITH LOWS IN THE
MID TO UPPER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 AM CDT THU SEP 5 2013
HEAT WAVE CONTINUES INTO THE WEEKEND. CENTER OF THE RIDGE WILL
DRIFT EAST INTO THE WEEKEND AS TROUGH/LOW COMES ONSHORE ACROSS
THE PAC NW. 850 MB TEMPS CONTINUE TO SURGE ABOVE 30 DEGREES
ACROSS MOST OF THE AREA DURING THE AFTERNOON BOTH FRIDAY AND
SATURDAY. GUIDANCE HAS HIGHS AROUND 100 DEGREES FOR MOST OF THE
CWA...AND WILL NOT STRAY FROM GUIDANCE. DISTURBANCES CONTINUES TO
ROTATE AROUND THE RIDGE...AND WILL NEED TO KEEP A CHANCE FOR
STORMS ACROSS THE NORTHWEST INTO NORTH CENTRAL. LOWER LEVELS ARE
FAIRLY DRY HOWEVER MOISTURE ALOFT SHOULD BE ENOUGH TO GET THINGS
TO DEVELOP OVER THE HIGHER TERRAIN TO THE WEST THEN DRIFT EAST.
QUESTION IS HOWEVER MUCH COVERAGE AND HOW MUCH WILL REACH THE
GROUND. WILL CONTINUE SOME ISOLD POPS IN THE FORECAST WITH LOW
CONFIDENCE.
TROUGH CROSS THE NORTHERN ROCKIES LATE IN THE WEEKEND INTO THE
FIRST OF NEXT WEEK. THIS WILL PUSH THE CENTER OF THE RIDGE TO THE
SE...WITH 850 MB TEMPS TO BEGIN TO COOL SUNDAY. STILL GOING TO BE
TOASTY FOR SEPT...WITH HIGHS IN THE 90S FOR SUNDAY. MONDAY A
SURFACE COLD FRONT WILL ENTER THE NW PART OF THE CWA. TIMING IS
STILL AN ISSUE WITH MODELS ALTHOUGH SOME IMPROVEMENT FROM THE 12Z
RUNS. WILL SEE A CHANCE FOR STORMS AS THE FRONT SLOWLY PUSHES
ACROSS THE AREA. TUESDAY WITH CLOUDS AND A CHANCE FOR
STORMS...TEMPS CLOSER TO SEASONAL...LOWER TO MID 80S. BY
WEDNESDAY COOLER HIGH PRESSURE WILL BUILD ACROSS THE AREA...WITH
SHOWERS TO PUSH TO THE SOUTHEAST. HIGHS SHOULD STILL BE ABLE TO
WARM INTO THE 80S...AS THE SUN RETURNS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1125 PM CDT WED SEP 4 2013
TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB
THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR
AND RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM
DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83.
HOWEVER IT LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING
CONVECTION TOO FAR EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS
QUESTIONABLE. IF ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY
17Z THURSDAY.
OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE
CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS
SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND
18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z-
00Z.
&&
.FIRE WEATHER...
ISSUED AT 400 AM CDT THU SEP 5 2013
MINIMUM RELATIVE HUMIDITIES WILL FALL TO AROUND 20 PERCENT IN THE
VICINITY OF THE SURFACE TROUGH OVER THE NEBRASKA PANHANDLE THIS
AFTERNOON. THIS IS ALSO WHERE WINDS WILL BE THE LIGHTEST. THINGS
WILL CONTINUE TO DRY OVER THE NEXT SEVERAL DAYS WITH LITTLE IN THE
WAY OF PRECIPITATION. THAT TIME OF YEAR FOR CROPS DRYING. FIRE
DANGER WILL INCREASE.
&&
.CLIMATE...
ISSUED AT 400 AM CDT THU SEP 5 2013
A RECORD HERE OR THERE MAY FALL OVER THE NEXT FEW DAYS DURING THIS
HEAT WAVE...HOWEVER MOST ARE SAFE. OVER THE NEXT 3 DAYS HIGHS WILL
APPROACH AND POSSIBLY SURPASS 100 DEGREES ACROSS THE AREA. RECORD
HIGHS ARE ALL AT OR ABOVE 100. FOR THE 5TH, 6TH, AND 7TH...MANY OF
THE RECORD HIGHS ARE NEAR THE WARMEST OF ALL OF SEPTEMBER...WHICH
MAKES IT TOUGHER TO REACH. BELOW ARE THE RECORD HIGHS FOR THE NEXT
3 DAYS. FRIDAY AND SATURDAY ARE THE BEST CHANCE TO SET A RECORD
HIGH.
LOCATION...RECORD HIGH THURS...FRI...SAT.
NORTH PLATTE...105/1931...102/1931...102/1959.
VALENTINE......103/1998...101/1980...100/1940.
BROKEN BOW.....105/1931...101/1984+...102/1940.
IMPERIAL.......110/1931...105/1959+...103/1969.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...POWER
SHORT TERM...POWER
LONG TERM...MASEK
AVIATION...CDC
FIRE WEATHER...POWER
CLIMATE...MASEK
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
113 AM CDT THU SEP 5 2013
.SYNOPSIS...
ISSUED AT 342 PM CDT WED SEP 4 2013
UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS
CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH
OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE
PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE
ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN
SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS
THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED
FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S
ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA.
&&
.UPDATE...
ISSUED AT 112 AM CDT THU SEP 5 2013
UPDATING FORECAST TO ACCOUNT FOR ON GOING PRECIPITATION OVER
SOUTHWEST NEBRASKA. INCREASED CLOUDS ADJUSTED WINDS AND EXPANDED
AREA OF PRECIPITATION.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE
SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED
WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE
WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION
ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE
ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON
THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE
WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE
PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE
ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ
RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY
A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST.
ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE
AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES
PASSING THROUGH THE FLOW.
AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85
T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL
TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL
OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE
ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT
100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND
WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH
DAKOTA STATE LINE.
THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND
SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO
NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO
NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION
THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME
HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR
IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION
WILL BE SPOTTY AND FAIRLY LIGHT.
IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY
WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE
THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT
THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE
GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE
TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY.
STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT
FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING
TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR
PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE
TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES
APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT
MONDAY THROUGH WEDNESDAY PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1125 PM CDT WED SEP 4 2013
TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB
THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND
RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM
DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT
LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR
EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF
ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY.
OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE
CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS
SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND
18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z-
00Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...POWER
SYNOPSIS...JACOBS
SHORT TERM...JACOBS
LONG TERM...SPRINGER
AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1132 PM CDT WED SEP 4 2013
.SYNOPSIS...
ISSUED AT 342 PM CDT WED SEP 4 2013
UPPER RIDGE OF HIGH PRESSURE CENTERED OVER THE CENTRAL HIGH PLAINS
CONTINUES TO DOMINATE THE OVERALL SYNOPTIC PATTERN...WITH A TROUGH
OF LOW PRESSURE OVER THE NORTHEASTERN STATES...AND ONE OFF THE
PACIFIC NORTHWEST COAST. AT THE SURFACE...A TROUGH OF LOW PRESSURE
ARCHES FROM EAST CENTRAL COLORADO ACROSS THE PANHANDLE INTO SOUTHERN
SOUTH DAKOTA. SURFACE HIGH PRESSURE REMAINS OFF TO THE EAST ACROSS
THE MID MISSISSIPPI RIVER VALLEY. AS OF 20Z TEMPERATURES RANGED
FROM THE MID 80S OVER THE HEART OF THE SANDHILLS...TO THE MID 90S
ALONG THE NORTH PLATTE RIVER VALLEY NEAR KOGA.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
THUNDERSTORM CHANCES AND ABNORMALLY WARM TEMPERATURES HIGHLIGHT THE
SHORT TERM DISCUSSION. DESPITE LARGE SCALE SUBSIDENCE ASSOCIATED
WITH THE UPPER LEVEL RIDGE...SUFFICIENT DAYTIME HEATING WILL COMBINE
WITH A WEAK MIDLEVEL DISTURBANCE TO SPARK OFF ISOLATED CONVECTION
ACROSS WESTERN AND SOUTHWEST NEBRASKA THIS EVENING. OBJECTIVE
ANALYSIS INDICATES 1000-2000 J/KG OF MUCAPE WITH EFFECTIVE SHEAR ON
THE ORDER OF 30 KTS. ISOLATED STRONG WIND GUSTS WOULD BE POSSIBLE
WITHIN OR NEAR ANY CELL THAT DEVELOPS...ESPECIALLY GIVEN THE
PROJECTED INVERTED V SOUNDINGS WITH LARGE T/TD SPREADS. THE
ACTIVITY MAY CONTINUE ACROSS THE HEART OF THE CWA OVERNIGHT AS A LLJ
RE-DEVELOPS WITH INCREASING CONVERGENCE & WAA...FOR THIS WILL CARRY
A SLIGHT CHANCE MENTION THROUGH 15Z THURSDAY FROM WEST TO EAST.
ADDITIONAL STORMS WILL BE POSSIBLE THURSDAY AFTERNOON...WITH THE
AMPLIFIED RIDGE ATOP THE CWA...AND SUBSEQUENT WEAK DISTURBANCES
PASSING THROUGH THE FLOW.
AS FOR TEMPERATURES...HIGHS WILL REMAIN WELL ABOVE AVERAGE AS H85
T/S WARM WELL ABOVE 30C FOR MOST LOCATIONS. HIGHS ON THURSDAY WILL
TOP OUT ONCE AGAIN IN THE LOW TO MID 90S FOR MOST LOCATIONS.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM CDT WED SEP 4 2013
FOR THE MID-RANGE FORECAST...WEATHER WILL BE HOT AND DRY. MODEL
OUTPUT STATISTICS FROM THE THREE AVAILABLE BULLETINS INDICATE
ANOTHER HEAT WAVE IN THE MIDDLE RANGE OF THE FORECAST. IT SEEMS THAT
100 PLUS IS NOT OUT OF THE QUESTION FRIDAY OVER ALL OF CENTRAL AND
WESTERN NEBRASKA WITH THE HOTTEST WEATHER ALONG THE NEBRASKA-SOUTH
DAKOTA STATE LINE.
THE GFS SHOWS THE HOTTEST AIR SINKING SOUTH TO SOUTH CENTRAL AND
SOUTHWEST NEBRASKA FOR SATURDAY AS A WEAK FRONT DRIFTS ACROSS INTO
NEBRASKA...BUT THAT LASTS ONLY ONE DAY. AS THE FRONT COMES INTO
NORTHERN NEBRASKA...IT WILL GENERATE SOME LIFT. A CROSS-SECTION
THROUGH NORTHERN NEBRASKA SHOWS INSTABILITY ABOVE 700MB AND SOME
HUMIDITY 75 PERCENT OR HIGHER. HOWEVER...BELOW THAT LEVEL...THE AIR
IS FAIRLY DRY AT 40-50 PERCENT. THE RESULT IS THAT PRECIPITATION
WILL BE SPOTTY AND FAIRLY LIGHT.
IT IS NOT UNTIL MONDAY THAT SIGNIFICANT RELIEF FROM THE HOT AND DRY
WEATHER CAN BE EXPECTED. AT THAT TIME...A MODERATE FRONT WILL MOVE
THROUGH NEBRASKA. THE GFS IS ABOUT 12 HOURS FASTER WITH THE FRONT
THAN IS THE GEM AND THE 12Z ECMWF IS ABOUT SIX HOURS FASTER THAN THE
GEM. THE DIFFERENCES AMONG THE MODELS COULD HAVE AN EFFECT ON THE
TIMING OF THE PRECIPITATION AND ALSO ON THE TEMPERATURES ON TUESDAY.
STILL...THERE IS ENOUGH AGREEMENT THAT WE CAN NUDGE THE CURRENT
FORECAST TO A BLEND OF THE THREE EXTENDED MODELS. THIS SHOULD BRING
TEMPERATURES 5-15 DEGREES LOWER MONDAY OR TUESDAY AND A CHANCE FOR
PRECIPITATION...THOUGH THERE IS STILL UNCERTAINTY REGARDING THE
TIMING...AMOUNT AND EXTENT OF THE PRECIPITATION. STILL...IT DOES
APPEAR THAT THE BETTER CHANCES FOR PRECIPITATION WILL BE IN THAT
MONDAY THROUGH WEDNESDAY PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1125 PM CDT WED SEP 4 2013
TWO AREAS OF THUNDERSTORMS MOVED NORTH AND SOUTH THROUGH WRN NEB
THIS EVENING AS ADVERTISED BY THE SHORT RANGE MODELS. THE HRRR AND
RAP MODELS NOW SUGGEST THE POTENTIAL FOR ISOLATED STORM
DEVELOPMENT OVERNIGHT ACROSS NCNTL NEB EAST OF HIGHWAY 83. HOWEVER IT
LOOKS LIKE THE MODELS ARE CARRYING THE ONGOING CONVECTION TOO FAR
EAST SO THE POTENTIAL FOR STORM DEVELOPMENT IS QUESTIONABLE. IF
ANY STORMS DEVELOP...THEY SHOULD DISSIPATE BY 17Z THURSDAY.
OTHERWISE VFR IS EXPECTED THROUGH 22Z THURSDAY. THEREAFTER MORE
CONVECTION COULD DEVELOP ACROSS WRN NEB SIMILAR TO TODAY. THIS IS
SHOWN BY THE NAM WHICH FIRES OFF TSTMS ON THE LARAMIE RANGE AROUND
18Z-21Z THURSDAY WHICH COULD BEGIN AFFECTING WRN NEB AROUND 23Z-
00Z.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...JACOBS
SHORT TERM...JACOBS
LONG TERM...SPRINGER
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
950 PM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL BUILD OVER THE AREA THROUGH THE
WEEKEND... WHILE WEAKENING. A DRY COLD FRONT WILL MOVE SOUTHWARD
THROUGH THE AREA EARLY MONDAY... FOLLOWED BY ANOTHER HIGH PRESSURE
AREA PUSHING INTO THE REGION FROM THE NORTH THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 PM FRIDAY...
THE HIGH PRESSURE WAS CENTERED OVER PA THIS EVENING... AND CONTINUED
TO BUILD SOUTHWARD INTO GA/FL. THE FLOW AROUND THE HIGH WAS MOSTLY
DRY AT ALL LEVELS EXCEPT BETWEEN H850 TO AROUND H900. THIS MOISTURE
SHOWS UP ON THE WALLOPS SOUNDING BEST AND WAS LOCATED IN LINE WITH A
MORE ONSHORE FLOW OFF THE ATLANTIC INTO THIS REGION. LOCALLY... SOME
CLOUDINESS WAS SPREADING INTO OUR NE ZONES ALREADY... VERY LIMITED
IN DEPTH AS WELL. WE WILL CONTINUE THE PARTLY CLOUDY FORECAST NE
INTO THE CENTRAL AREAS... AND MOSTLY CLEAR ELSEWHERE. TEMPERATURES
ARE IN LINE WITH THE CURRENT FORECAST LOWS IN THE UPPER 50S TO LOWER
60S AS WELL.
FOR SATURDAY/SATURDAY NIGHT: A QUIET DAY WITH WEAK MID LEVEL
TROUGHING JUST OFF THE EAST COAST AND THE STRONG ANTICYCLONE HOLDING
OVER CO/NE/KS... WHILE AT THE SURFACE... THE QUICKLY WEAKENING RIDGE
ACROSS THE AREA IS SUPPLANTED BY A WEAK LEE TROUGH... AHEAD OF THE
NEXT BACKDOOR FRONT STILL WELL TO OUR NNW. ANY MORNING STRATOCUMULUS
SHOULD MIX OUT QUICKLY SATURDAY MORNING WITH PLENTY OF DRY AIR ALOFT
AND NEAR THE GROUND TO HELP DISPERSE THIS MOISTURE ONCE HEATING AND
MIXING BEGIN. WE SHOULD STILL SEE SCATTERED FLAT CUMULUS IN THE
AFTERNOON WITH THE INVERSION ALOFT HOLDING STRONG. BUT SUBSIDENCE
THROUGH THE COLUMN AND DRY AIR ALOFT IN SITU AND UPSTREAM WILL
ASSURE THAT WE SEE MORE SUN THAN CLOUDS. THICKNESSES ARE EXPECTED TO
START OUT AROUND 15 M BELOW NORMAL BUT RISE NEARLY 25 M THROUGH THE
DAY... SO EXPECT TEMPS TO BE BELOW NORMAL BUT STILL A BIT WARMER
THAN TODAY... 80-85. LOWS 59-65 WITH A FEW THIN MID CLOUDS SPILLING
OVER THE TOP OF THE RIDGE OVER THE NRN PLAINS DROPPING SE TOWARD NC.
-GIH
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 250 PM FRIDAY...
FOR SATURDAY/SATURDAY NIGHT: A QUIET DAY WITH WEAK MID LEVEL
TROUGHING JUST OFF THE EAST COAST AND THE STRONG ANTICYCLONE HOLDING
OVER CO/NE/KS... WHILE AT THE SURFACE... THE QUICKLY WEAKENING RIDGE
ACROSS THE AREA IS SUPPLANTED BY A WEAK LEE TROUGH... AHEAD OF THE
NEXT BACKDOOR FRONT STILL WELL TO OUR NNW. ANY MORNING STRATOCUMULUS
SHOULD MIX OUT QUICKLY SATURDAY MORNING WITH PLENTY OF DRY AIR ALOFT
AND NEAR THE GROUND TO HELP DISPERSE THIS MOISTURE ONCE HEATING AND
MIXING BEGIN. WE SHOULD STILL SEE SCATTERED FLAT CUMULUS IN THE
AFTERNOON WITH THE INVERSION ALOFT HOLDING STRONG. BUT SUBSIDENCE
THROUGH THE COLUMN AND DRY AIR ALOFT IN SITU AND UPSTREAM WILL
ASSURE THAT WE SEE MORE SUN THAN CLOUDS. THICKNESSES ARE EXPECTED TO
START OUT AROUND 15 M BELOW NORMAL BUT RISE NEARLY 25 M THROUGH THE
DAY... SO EXPECT TEMPS TO BE BELOW NORMAL BUT STILL A BIT WARMER
THAN TODAY... 80-85. LOWS 59-65 WITH A FEW THIN MID CLOUDS SPILLING
OVER THE TOP OF THE RIDGE OVER THE NRN PLAINS DROPPING SE TOWARD NC.
-GIH
1025 MB CONTINENTAL POLAR SURFACE HIGH PRESSURE CENTERED OVER PA/NY
THIS AFTERNOON WILL CONTINUE TO MODIFY/WEAKEN...RELATIVELY QUICKLY
GIVEN THE STILL RELATIVELY HIGH PRE-EQUINOX SUN ANGLE...AS IT DRIFTS
INTO THE SOUTHEASTERN US BY EARLY SUNDAY. MEANWHILE...AN ELONGATED
MID-UPPER VORTICITY AXIS AROUND THE NORTHERN PERIPHERY OF A
SUB-TROPICAL RIDGE OVER THE ROCKIES...WILL WEAKLY AMPLIFY TOWARD THE
BASE OF A STRONGLY POSITIVELY-TILTED LONGWAVE TROUGH AXIS FORECAST
TO DEVELOP FROM THE WESTERN ATLANTIC TO THE TX GULF COAST. THE
AMPLIFICATION OF THE SHORTWAVE TROUGH AXIS PARENT TO THE VORTICITY
CENTERS IN NORTHWESTERLY FLOW ALOFT WILL PROMOTE THE DEVELOPMENT OF
A LEE SIDE SURFACE TROUGH OVER THE CAROLINAS ON SUNDAY...BEFORE A
REINFORCING COLD FRONT ACCOMPANYING THE SHORTWAVE TROUGH AXIS DRIFTS
THROUGH CENTRAL NC SUN NIGHT.
AS IT HAS APPEARED FOR DAYS NOW...MOISTURE IN THE NORTHWESTERLY FLOW
REGIME...BOTH BOUNDARY AND DEEP LAYER...AND RESULTANT INSTABILITY...
ARE EXPECTED TO BE LIMITED. AS SUCH...IT WILL BE DIFFICULT FOR THE
ATMOSPHERE TO SUPPORT PRECIPITATION HERE...WITH THE MOST LIKELY
SCENARIO BEING A FEW WIDELY SCATTERED REMNANT SHOWERS OR SPRINKLES
DRIFTING INTO THE NORTHERN PIEDMONT DURING THE LATE AFTERNOON AND
EVENING...AFTER DEVELOPING AND MOVING THROUGH A MORE FAVORABLY
UNSTABLE ENVIRONMENT UPSTREAM. OTHER ISOLATED TO WIDELY SCATTERED
SEA BREEZE CONVECTION WILL LIKELY REMAIN OVER COASTAL AREAS...OR
PERHAPS DRIFT INTO SOUTHERN SAMPSON COUNTY BY SUNSET.
THE WARM SECTOR SHOULD BE EFFECTIVELY SHUNTED TO OUR SOUTH...OR TO
THE FAR SOUTHERN TIER OF NC BY MON. HOWEVER...THE COMBINATION OF
WEAKENING LOW LEVEL FRONTAL FORCING INVOF THE BOUNDARY...AND
RESIDUALLY RICH LOW MOISTURE CHARACTERIZED BY UPPER 60S TO NEAR 70
DEGREES SURFACE DEWPOINTS IN POST-FRONTAL ENE LOW LEVEL FLOW...
WARRANTS A CONTINUED SLIGHT CHANCE OF SHOWERS AND STORMS MAINLY
FROM THE SOUTHERN PIEDMONT TO THE SOUTHERN COASTAL PLAIN.
TEMPERATURES SHOULD REBOUND NICELY WITH THE LEE TROUGHING AND BRIEF
RESPITE FROM ENE TO NE LOW LEVEL FLOW...WITH TEMPERATURES IN THE 87
TO 92 DEGREE RANGE SUN...THEN 3-5 DEGREES COOLER WITH A BRIEF RETURN
OF THE ENE LOW LEVEL FLOW ON MON. PRE- AND POST-FRONTAL PROJECTED
LOW LEVEL THICKNESSES SUPPORT LOWS IN THE MIDDLE TO UPPER 60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 PM FRIDAY...
A SUB-TROPICAL RIDGE OVER THE CENTRAL PLAINS WILL WEAKEN AND MOVE
EASTWARD ACROSS OUR REGION THROUGH MID-WEEK...WHILE THE POSITIVE
HEIGHT ANOMALY IN THE MEAN RETROGRADES/RELOADS OVER THE ROCKIES. IN
A DEEP LAYER ANTICYCLONIC FLOW...AND ASSOCIATED MID LEVEL WARMTH AND
SUBSIDENCE...WILL LIKELY INHIBIT DEEP CONVECTIVE DEVELOPMENT AWAY
FROM OROGRAPHIC AND SEA BREEZE FORCING THROUGH MID-WEEK...WITH JUST
THE SLIGHTEST OF A CHANCES OF A SHOWER OR STORM DRIFTING INTO THE
FAR WESTERN PIEDMONT. THE AFOREMENTIONED RETROGRESSION OF THE RIDGE
IN THE MEAN WILL ALLOW A PROGRESSIVE TROUGH ALOFT TO DEVELOP
EASTWARD ACROSS THE GREAT LAKES AND EAST COAST LATE WEEK INTO EARLY
NEXT WEEKEND. A COLD FRONT WILL ACCOMPANY THE TROUGH...AND THE
TIMING OF THIS FEATURE AND NEXT LEGITIMATE CHANCE OF SHOWERS AND
STORMS... LOOKS LIKE LATE THU-FRI. CONTINUED WARM...WITH HIGHS
MOSTLY IN THE UPPER 80S. LOWS MID-UPPER 60S.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 730 PM FRIDAY...
VFR CONDITIONS PREVAIL ACROSS ALL TAF SITES THIS EVENING WITH SOME
SCATTERED CLOUDS AROUND 5 KFT...MORE PREVALENT IN THE EAST. WINDS
WILL BE LIGHT AND VARIABLE OVERNIGHT AS A SURFACE HIGH PRESSURE
PARKS OVER THE AREA. THIS COULD LEAD TO SOME VARIABLE WIND
DIRECTIONS TOMORROW WITH WESTERN SITES EXPERIENCING LIGHT WINDS OUT
OF THE SOUTHWEST AND EASTERN SITES OUT OF THE NORTHEAST. SUFFICE TO
SAY THAT WINDS WILL BE LARGELY LIGHT AND VARIABLE THROUGH THE TAF
PERIOD REGARDLESS OF WHERE THE HIGH ENDS UP. OVERNIGHT
TONIGHT...FORECAST SOUNDINGS AND CROSSOVER TEMPERATURES SUGGEST SOME
TEMPORARY LOW STRATUS IN THE NORTHWEST. HRRR SIMULATION OF CEILINGS
SHOW LIFR CONDITIONS POSSIBLE AFTER 8Z THROUGH SUNRISE BUT IT MIGHT
END UP PRIMARILY WEST OF KINT AND KGSO. WILL LEAVE IN THE TAFS AS A
TEMPO GROUP FOR NOW.
LONG TERM: PRIMARILY VFR CONDITIONS SHOULD DOMINATE THE REGION
THROUGH THE MAJORITY OF THE LONG TERM.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...BADGETT
SHORT TERM...MWS
LONG TERM...MWS
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
731 PM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL DROP ACROSS THE AREA THIS WEEKEND
THEN OFFSHORE BY LATE SUNDAY. A WEAK COLD FRONT WILL DISSIPATE
OVER THE REGION LATE MONDAY...FOLLOWED BY HIGH PRESSURE THROUGH
MID-WEEK. A COLD FRONT IS EXPECTED TO CROSS THE AREA NEXT FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 615 PM FRIDAY...THE FORECASTS HAS BEEN UPDATED A LITTLE EARLY
TO ACCOUNT FOR A CLUSTER OF THUNDERSTORMS MOVING SOUTHWESTWARD DOWN
THE COAST OF NORTH CAROLINA...NOW APPROACHING SURF CITY. THIS
ACTIVITY IS ROOTED WITHIN A NARROW ZONE OF FAIRLY SUBSTANTIAL
SURFACE-BASED INSTABILITY (CAPE NEARLY 2000 J/KG) RIGHT ALONG THE
COAST WHERE DEWPOINTS HAVE RECOVERED TO 70-72 DEGREES DUE TO THE
AFTERNOON SEABREEZE. ON THE WEST (INLAND) SIDE OF THE SEABREEZE
WHERE DEWPOINTS ARE 7-10 DEGREES LOWER THERE IS NEGLIGIBLE
SURFACE-BASED CAPE AND VIRTUALLY NO CHANCE OF PRECIPITATION THIS
EVENING.
THE LATEST THREE HRRR RUNS SHOW THERE IS POTENTIAL FOR THIS
CONVECTION TO CONTINUE ALL THE WAY DOWN TO SOUTHPORT. 0-6 KM BULK
SHEAR IS NEAR 30 KNOTS WHICH IS SUPPORTING THE MULTICELLULAR
CHARACTERISTICS WE ARE OBSERVING. PRECIPITABLE WATER ONLY AROUND 1.3
INCHES...KEPT LOW BY ALL THE DRY AIR IN THE MID LEVELS...IS
OFFSETTING WHAT COULD BE A SERIOUS FLOODING THREAT GIVEN THE SLOW
OBSERVED STORM MOTION. I HAVE INCREASED FORECAST POPS ALONG THE CAPE
FEAR COASTLINE THROUGH ABOUT 02Z...WITH CHANCES FOR PRECIPITATION
DROPPING BELOW MENTIONABLE THRESHOLDS BY MIDNIGHT EVERYWHERE ON
LAND.
NO SIGNIFICANT CHANGES HAVE BEEN MADE TO OTHER FORECAST VARIABLES AT
THIS TIME. PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...
ONE ONLY NEEDS TO LOOK AT THE VISIBLE
SATELLITE IMAGERY COMBINED WITH SURFACE OBS THIS AFTN TO UNDERSTAND
THE SYNOPTIC ENVIRONMENT. TEMPS IN THE UPPER 80S BUT WITH ONLY
SCATTERED SHALLOW CU DEVELOPMENT IS A CLEAR INDICATOR OF DRY HIGH
PRESSURE BUILDING INTO THE AREA. THIS IS BEHIND A COLD FRONT WHICH
HAS SUNK WELL SOUTH OF THE CWA...AND THIS HIGH PRESSURE WILL
CONTINUE TO RIDGE DOWN THE COAST THROUGH TONIGHT. WHILE SURFACE HIGH
PRESSURE WILL ACT TO INHIBIT MUCH CONVECTION TODAY...MID-LEVEL
SHORTWAVE ROTATING AROUND LONGWAVE TROUGH HAS THE POTENTIAL TO
CREATE SOME ISOLATED SHOWERS THIS EVENING AND TONIGHT.
HIGH RES GUIDANCE (WRF/HRRR) CONTINUES TO SUGGEST THAT SCATTERED
SHOWERS WILL DEVELOP NORTH OF THE LOCAL AREA THIS EVENING AND ADVECT
SOUTH INTO THE NORTHERN ZONES TONIGHT. HAVE NOTICED THAT THESE
MODELS ARE INITIALIZING "HOT" HOWEVER...AND THE CONVECTION PROGGED
TO BE ONGOING AT THE PRESENT TIME HAS NOT MATERIALIZED.
STILL...FORECAST SOUNDINGS SUGGEST AMPLE MOISTENING OF THE
1000-800MB LAYER TONIGHT WHICH COMBINED WITH SOME MID-LEVEL FORCING
BENEATH THE SHORTWAVE COULD GENERATE A SHOWER OR TWO...CONFINED TO
THE NORTHEAST PORTIONS OF THE CWA. HAVE CAPPED POP AT
SCHC/ISOLATED...AND SIGNIFICANT DRY AIR ABOVE 700MB WILL INHIBIT
CONVECTION FROM BECOMING STRONG...THUS DO NOT EVEN ANTICIPATE
LIGHTNING. AT THE VERY LEAST...SOME ENHANCED MID LEVEL CLOUD COVER
IS EXPECTED TO DROP SOUTH TO NORTH TONIGHT.
MINS TONIGHT WILL BE A LITTLE TRICKY WITH CONTINUED NE WINDS AND THE
POTENTIALLY ENHANCED CLOUD COVER...ESPECIALLY IN THE N/NE ZONES.
HAVE KEPT MINS SLIGHTLY ABOVE GUIDANCE...SIDING MORE WITH THE WARMER
MET NUMBERS...WHICH HAS GENERALLY PERFORMED BETTER THAN THE MAV THIS
MONTH.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...MAIN FEATURE OF NOTE SATURDAY AND SUNDAY IS
CANADIAN HIGH PRESSURE DROPPING SE ACROSS THE EASTERN CAROLINAS
SATURDAY THEN OFFSHORE BY LATE SUNDAY. NE-E WIND FLOW IN THE
LOWEST SEVERAL THOUSAND FEET OF THE ATMOSPHERE SATURDAY COULD
BRING A MODERATE AMOUNT OF STRATO-CUMULUS SO CERTAINLY DO NOT
WANT TO ADVERTISE ALL OUT "SUNNY". SPOTTY LIGHT SHOWERS CANNOT
BE RULED OUT ALONG THE NORTH COAST AROUND DAYBREAK SATURDAY BUT
WEAK SUBSIDENCE IN WAKE OF AN IMPULSE MOVING SE AND OFFSHORE
SHOULD CONFINE SHOWERS SATURDAY OVER THE 0-20 NM COASTAL WATERS
AND NORTH TO CAPE LOOKOUT. AS THE HIGH MOVES OFFSHORE LATE ON
SUNDAY...A WEAK SHORT-WAVE AND BRIEF SURFACE TROUGH INLAND MAY
TRIP OFF A FEW SHOWERS SUNDAY AFTERNOON AND EVENING. AS THIS
FEATURE DROPS SOUTH OF THE AREA...THE LEADING EDGE OF CANADIAN
HIGH PRESSURE PUSHES A WEAK BACK DOOR FRONT SOUTH INTO OUR NC
ZONES. SUBSIDENCE ALOFT APPEARS TO ACCOMPANY THIS FEATURE WITH
DRY NORTH FLOW ALOFT AND NO MENTIONABLE POPS PLANNED EARLY MON.
SUNDAY MORNING SHOULD BE A FEW DEGREES COOLER THAN SAT MORNING
MAINLY BY VIRTUE OF LESS CLOUDS...WITH WIDESPREAD 60S EXPECTED
DAYBREAK SUNDAY. MAXIMUMS TEMPS SHOULD BE WARMER ON SUNDAY FOR
SIMILAR REASONS OF LESS CLOUD COVER. RETURN FLOW BEGINS LATE
SUNDAY EVENING WITH A WEAK WIND SHIFT TO NORTH OVER OUR NC
ZONES INTO DAYBREAK MONDAY AS THE CANADIAN HIGH DIPS INTO THE
MID-ATLANTIC REGION.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 3 PM FRIDAY...MID LEVEL RIDGING WILL BE THE PREVAILING
FEATURE FOR THE FIRST HALF OF THE FORECAST PERIOD. THERE WILL BE
SUFFICIENT MOISTURE IN THE COLUMN...PRECIPITABLE WATER VALUES OF
1.80 INCHES... TO MAINTAIN SLIGHT CHANCE POPS MONDAY BEFORE A
SURGE OF DRIER AIR MOVES IN FROM THE NORTHEAST. THIS WILL KEEP
POPS OUT OF THE PICTURE FOR TUESDAY AND WEDNESDAY. A SIGNIFICANT
MID LEVEL TROUGH WILL BRING ANOTHER RELATIVELY STRONG COLD FRONT
ACROSS THE AREA FRIDAY. THE SOUTHERLY FLOW AHEAD OF THIS SYSTEM
WILL ALLOW SLIGHT CHANCE POPS TO CREEP BACK INTO THE FORECAST
THURSDAY WITH THE BETTER FORCING WARRANTING CHANCE VALUES FRIDAY.
TEMPERATURE FORECAST LOOKS STABLE WITH VALUES JUST A DEGREE OR TWO
ABOVE CLIMATOLOGY THROUGH THE PERIOD.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 00Z...CURRENTLY VFR AT ALL TERMS THIS EVENING WITH LIGHT
NORTHEAST WINDS. WILL HOLD ONTO VCSH AT KILM EARLY THIS EVENING AS
RADAR SHOWS A FEW SHOWERS NEAR THE CAPE FEAR AREA ASSOCIATED WITH AN
UPPER SHORTWAVE. DO NOT ANTICIPATE ANY DIRECT IMPACTS TO KILM ATTM.
CONTINUED NORTHEAST FLOW OVERNIGHT SHOULD LIMIT THE FOG POTENTIAL
FOR OUR CWA. FOG-PRONE KCRE COULD SEE TEMPO MVFR VSBYS BEFORE 06Z IF
THE WINDS GO CALM...BUT CONFIDENCE IS FAIRLY LOW. NAM FORECAST
SOUNDINGS HINT AT SOME FOG EARLY SATURDAY FOR KFLO/KLBT...BUT THIS
SEEMS OVERDONE GIVEN THE BOUNDARY LAYER WINDS AND THE LOWER SFC
DEWPOINTS INLAND. THEREFORE...WILL ONLY MENTION LIGHT GROUND FOG AND
TEMPO MVFR STRATUS FOR THESE SITES BEFORE 12Z. EXPECT VFR ON
SATURDAY AS SFC HIGH PRESSURE RIDGES INTO THE CAROLINAS. THE WINDS
WILL BE NORTHEAST IN THE MORNING...BECOMING E-SE AOB 10 KTS IN THE
AFTERNOON.
EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS IS POSSIBLE SUNDAY
THROUGH WEDNESDAY...MAINLY INLAND. SLIGHT CHANCE OF SHOWERS ON
MONDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 615 PM FRIDAY...I HAVE UPDATED THE MARINE FORECAST TO INCREASE
THE POTENTIAL OF THUNDERSTORMS THIS EVENING...MAINLY FROM AROUND
CAPE FEAR NORTH TO SURF CITY. LATEST NEAR-TERM HIGH RESOLUTION
MODELS SHOW THE THUNDERSTORM ACTIVITY APPROACHING SURF CITY MAY MAKE
IT DOWN TO SOUTHPORT OVER THE NEXT 2-3 HOURS. AFTER REVIEWING THE
LATEST SYNOPTIC MODELS FOR THE OVERNIGHT PERIOD I HAVE INCREASED
WIND SPEED FORECASTS BY A FEW KNOTS AFTER MIDNIGHT AND HAVE BACKED
WIND DIRECTIONS BY ABOUT 30 DEGREES...MORE NORTHEAST THAN EAST.
PREVIOUS DISCUSSION FROM 300 PM FOLLOWS...
HIGH PRESSURE BUILDING SOUTH FROM THE MID-ATLANTIC WILL CONTINUE TO
RIDGE ACROSS THE WATERS TONIGHT...PERSISTING THE NE WINDS PRESENTLY
OBSERVED AT THE LOCAL BUOYS. WHILE WINDS HAVE BEEN AROUND 10 KTS
MUCH OF THE DAY...A MDT NE SURGE IS STILL PROGGED TONIGHT...DRIVING
WINDS UP TO AROUND 15 KTS LATE IN THE PERIOD. THESE WINDS WILL FORCE
RISING WAVE HEIGHTS...FROM 1-3 FT...UP TO 3-4 FT LATE TONIGHT WITH A
5 SEC NE WIND CHOP REMAINING DOMINANT WITHIN THE WAVE SPECTRUM.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...MODERATE NE WINDS CAN BE EXPECTED ON THE
WATERS SATURDAY AS CANADIAN HIGH PRESSURE DROPS SE TOWARD THE
COASTAL WATERS. THIS MAY BRING SEAS TO 4 FEET OVER THE OUTER
WATERS AND ALSO NORTH OF CAPE FEAR...BUT NO ADVISORIES OR TSTMS
ARE EXPECTED. LIGHT SHOWERS HOWEVER MAY DOT THE WATERS SATURDAY
AND MAINLY NORTH OF CAPE FEAR. WINDS WILL EASE AND BECOME LIGHT
SATURDAY NIGHT AND SUNDAY AS THE HIGH MOVES NEARLY OVERHEAD OF
THE WATERS. AS THE HIGH MOVES OFFSHORE SUNDAY EVENING...EXPECT
WINDS TO BECOME S AND SW. HIGHEST WINDS AND SEAS ARE ANTICIPATED
SATURDAY WITH OVERALL IMPROVING CONDITIONS LATE SATURDAY AND
SUNDAY. LATE SUNDAY NIGHT INTO EARLY MONDAY HIGH PRESSURE DROPPING
FROM THE NORTH WILL BRING A WEAK COLD FRONT TO THE NC WATERS. THIS
SHOULD BRING A WIND-SHIFT NORTH OF CAPE FEAR BY DAYBREAK MONDAY.
LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 3 PM FRIDAY...EASTERLY WINDS INITIALLY WILL BACK TO
NORTHEASTERLY LATE MONDAY AND VACILLATE BETWEEN EAST TO NORTHEAST
THROUGH WEDNESDAY. THERE MAY BE A LATE SHIFT VERY LATE IN THE PERIOD
WEDNESDAY TO SOUTHEAST AS THE PATTERN SHIFTS A BIT BUT THIS WILL
NEED TO BE FINE TUNED IN SUBSEQUENT FORECASTS. WIND SPEEDS WILL
REMAIN EITHER SIDE OF TEN KNOTS THROUGHOUT THE PERIOD. WAVEWATCH
SEAS CONTINUE THE SEEMINGLY SUMMER LONG TREND OF BENIGN SEAS WITH
2-3 FEET PRIMARILY COMPRISED OF SHORTER PERIOD WIND WAVES.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...8
NEAR TERM...JDW/TRA
SHORT TERM...MJC
LONG TERM...SHK
AVIATION...BJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
730 PM EDT FRI SEP 6 2013
.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL BUILD OVER THE AREA THROUGH THE
WEEKEND... WHILE WEAKENING. A DRY COLD FRONT WILL MOVE SOUTHWARD
THROUGH THE AREA EARLY MONDAY... FOLLOWED BY ANOTHER HIGH PRESSURE
AREA PUSHING INTO THE REGION FROM THE NORTH THROUGH THE MIDDLE OF
NEXT WEEK.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 250 PM FRIDAY...
THROUGH TONIGHT: CONTINUED QUIET AND DRY... AS SURFACE HIGH PRESSURE
SHIFTS TO THE MIDATLANTIC COAST WHILE NOSING SOUTHWARD INTO NC.
EARLY IN THE EVENING THE NORTHEASTERLY LOW LEVEL FLOW IS EXPECTED TO
DRAW THE LOW LEVEL MOISTURE NOW OVER NE NC AND SE VA TOWARD THE
SW... SPREADING INTO EASTERN THEN SOUTHERN NC TONIGHT BEFORE
SHIFTING WESTWARD UP AGAINST THE HIGHER TERRAIN LATE TONIGHT.
SATELLITE IMAGERY SHOWS A SUBTLE SURFACE BOUNDARY ASSOCIATED WITH
THE LEADING EDGE OF THESE CLOUDS... POTENTIALLY RELATED TO A WEAK
MID LEVEL WAVE OBSERVED ON WATER VAPOR IMAGERY SWINGING THROUGH THE
WEAK EAST COAST TROUGH... AND THIS WILL PROVIDE ANOTHER SMALL SURGE
OF MORE STABLE AIR FROM THE NNE INTO NC TONIGHT. THE NAM IS MUCH
MORE EMPHATIC THAN THE GFS WITH THIS 925-850 MB MOISTURE... WITH THE
FORMER FAVORING A THICK OVERCAST DECK OF CLOUDS WHILE THE LATTER
DEPICTS MORE PATCHY CLOUDS. THE EXISTING CLOUDS UPSTREAM ARE NOT
OVERCAST... BUT AS THEY SPREAD TO THE SW AND WEST WHILE MIXING WANES
AND THE LOW LEVELS STABILIZE... WE COULD SEE THE HOLES IN THE CLOUD
COVER FILL IN AS THIS MOISTURE BECOMES TRAPPED BENEATH A LARGER
SUBSIDENCE INVERSION ALOFT WITH WEAK HORIZONTAL DISPERSION AS WINDS
BECOME EVEN LIGHTER. WILL SPREAD PARTLY CLOUDY SKIES OVER THE
EASTERN THEN SRN AND WRN CWA THROUGH THE NIGHT. TEMPS ARE TOUGH
SINCE THEY WILL DEPEND ON HOW MUCH CLOUD COVERAGE THERE IS OVERNIGHT
TO HAMPER RADIATIONAL COOLING. GUIDANCE HAS BEEN FAIRLY CONSISTENT
WITH UPPER 50S FAR NORTH AND WEST TRENDING TO LOW 60S SOUTHEAST...
SO WILL HOLD CLOSE TO THESE NUMBERS.
FOR SATURDAY/SATURDAY NIGHT: A QUIET DAY WITH WEAK MID LEVEL
TROUGHING JUST OFF THE EAST COAST AND THE STRONG ANTICYCLONE HOLDING
OVER CO/NE/KS... WHILE AT THE SURFACE... THE QUICKLY WEAKENING RIDGE
ACROSS THE AREA IS SUPPLANTED BY A WEAK LEE TROUGH... AHEAD OF THE
NEXT BACKDOOR FRONT STILL WELL TO OUR NNW. ANY MORNING STRATOCUMULUS
SHOULD MIX OUT QUICKLY SATURDAY MORNING WITH PLENTY OF DRY AIR ALOFT
AND NEAR THE GROUND TO HELP DISPERSE THIS MOISTURE ONCE HEATING AND
MIXING BEGIN. WE SHOULD STILL SEE SCATTERED FLAT CUMULUS IN THE
AFTERNOON WITH THE INVERSION ALOFT HOLDING STRONG. BUT SUBSIDENCE
THROUGH THE COLUMN AND DRY AIR ALOFT IN SITU AND UPSTREAM WILL
ASSURE THAT WE SEE MORE SUN THAN CLOUDS. THICKNESSES ARE EXPECTED TO
START OUT AROUND 15 M BELOW NORMAL BUT RISE NEARLY 25 M THROUGH THE
DAY... SO EXPECT TEMPS TO BE BELOW NORMAL BUT STILL A BIT WARMER
THAN TODAY... 80-85. LOWS 59-65 WITH A FEW THIN MID CLOUDS SPILLING
OVER THE TOP OF THE RIDGE OVER THE NRN PLAINS DROPPING SE TOWARD NC.
-GIH
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 250 PM FRIDAY...
1025 MB CONTINENTAL POLAR SURFACE HIGH PRESSURE CENTERED OVER PA/NY
THIS AFTERNOON WILL CONTINUE TO MODIFY/WEAKEN...RELATIVELY QUICKLY
GIVEN THE STILL RELATIVELY HIGH PRE-EQUINOX SUN ANGLE...AS IT DRIFTS
INTO THE SOUTHEASTERN US BY EARLY SUNDAY. MEANWHILE...AN ELONGATED
MID-UPPER VORTICITY AXIS AROUND THE NORTHERN PERIPHERY OF A
SUB-TROPICAL RIDGE OVER THE ROCKIES...WILL WEAKLY AMPLIFY TOWARD THE
BASE OF A STRONGLY POSITIVELY-TILTED LONGWAVE TROUGH AXIS FORECAST
TO DEVELOP FROM THE WESTERN ATLANTIC TO THE TX GULF COAST. THE
AMPLIFICATION OF THE SHORTWAVE TROUGH AXIS PARENT TO THE VORTICITY
CENTERS IN NORTHWESTERLY FLOW ALOFT WILL PROMOTE THE DEVELOPMENT OF
A LEE SIDE SURFACE TROUGH OVER THE CAROLINAS ON SUNDAY...BEFORE A
REINFORCING COLD FRONT ACCOMPANYING THE SHORTWAVE TROUGH AXIS DRIFTS
THROUGH CENTRAL NC SUN NIGHT.
AS IT HAS APPEARED FOR DAYS NOW...MOISTURE IN THE NORTHWESTERLY FLOW
REGIME...BOTH BOUNDARY AND DEEP LAYER...AND RESULTANT INSTABILITY...
ARE EXPECTED TO BE LIMITED. AS SUCH...IT WILL BE DIFFICULT FOR THE
ATMOSPHERE TO SUPPORT PRECIPITATION HERE...WITH THE MOST LIKELY
SCENARIO BEING A FEW WIDELY SCATTERED REMNANT SHOWERS OR SPRINKLES
DRIFTING INTO THE NORTHERN PIEDMONT DURING THE LATE AFTERNOON AND
EVENING...AFTER DEVELOPING AND MOVING THROUGH A MORE FAVORABLY
UNSTABLE ENVIRONMENT UPSTREAM. OTHER ISOLATED TO WIDELY SCATTERED
SEA BREEZE CONVECTION WILL LIKELY REMAIN OVER COASTAL AREAS...OR
PERHAPS DRIFT INTO SOUTHERN SAMPSON COUNTY BY SUNSET.
THE WARM SECTOR SHOULD BE EFFECTIVELY SHUNTED TO OUR SOUTH...OR TO
THE FAR SOUTHERN TIER OF NC BY MON. HOWEVER...THE COMBINATION OF
WEAKENING LOW LEVEL FRONTAL FORCING INVOF THE BOUNDARY...AND
RESIDUALLY RICH LOW MOISTURE CHARACTERIZED BY UPPER 60S TO NEAR 70
DEGREES SURFACE DEWPOINTS IN POST-FRONTAL ENE LOW LEVEL FLOW...
WARRANTS A CONTINUED SLIGHT CHANCE OF SHOWERS AND STORMS MAINLY
FROM THE SOUTHERN PIEDMONT TO THE SOUTHERN COASTAL PLAIN.
TEMPERATURES SHOULD REBOUND NICELY WITH THE LEE TROUGHING AND BRIEF
RESPITE FROM ENE TO NE LOW LEVEL FLOW...WITH TEMPERATURES IN THE 87
TO 92 DEGREE RANGE SUN...THEN 3-5 DEGREES COOLER WITH A BRIEF RETURN
OF THE ENE LOW LEVEL FLOW ON MON. PRE- AND POST-FRONTAL PROJECTED
LOW LEVEL THICKNESSES SUPPORT LOWS IN THE MIDDLE TO UPPER 60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 305 PM FRIDAY...
A SUB-TROPICAL RIDGE OVER THE CENTRAL PLAINS WILL WEAKEN AND MOVE
EASTWARD ACROSS OUR REGION THROUGH MID-WEEK...WHILE THE POSITIVE
HEIGHT ANOMALY IN THE MEAN RETROGRADES/RELOADS OVER THE ROCKIES. IN
A DEEP LAYER ANTICYCLONIC FLOW...AND ASSOCIATED MID LEVEL WARMTH AND
SUBSIDENCE...WILL LIKELY INHIBIT DEEP CONVECTIVE DEVELOPMENT AWAY
FROM OROGRAPHIC AND SEA BREEZE FORCING THROUGH MID-WEEK...WITH JUST
THE SLIGHTEST OF A CHANCES OF A SHOWER OR STORM DRIFTING INTO THE
FAR WESTERN PIEDMONT. THE AFOREMENTIONED RETROGRESSION OF THE RIDGE
IN THE MEAN WILL ALLOW A PROGRESSIVE TROUGH ALOFT TO DEVELOP
EASTWARD ACROSS THE GREAT LAKES AND EAST COAST LATE WEEK INTO EARLY
NEXT WEEKEND. A COLD FRONT WILL ACCOMPANY THE TROUGH...AND THE
TIMING OF THIS FEATURE AND NEXT LEGITIMATE CHANCE OF SHOWERS AND
STORMS... LOOKS LIKE LATE THU-FRI. CONTINUED WARM...WITH HIGHS
MOSTLY IN THE UPPER 80S. LOWS MID-UPPER 60S.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
AS OF 730 PM FRIDAY...
VFR CONDITIONS PREVAIL ACROSS ALL TAF SITES THIS EVENING WITH SOME
SCATTERED CLOUDS AROUND 5 KFT...MORE PREVALENT IN THE EAST. WINDS
WILL BE LIGHT AND VARIABLE OVERNIGHT AS A SURFACE HIGH PRESSURE
PARKS OVER THE AREA. THIS COULD LEAD TO SOME VARIABLE WIND
DIRECTIONS TOMORROW WITH WESTERN SITES EXPERIENCING LIGHT WINDS OUT
OF THE SOUTHWEST AND EASTERN SITES OUT OF THE NORTHEAST. SUFFICE TO
SAY THAT WINDS WILL BE LARGELY LIGHT AND VARIABLE THROUGH THE TAF
PERIOD REGARDLESS OF WHERE THE HIGH ENDS UP. OVERNIGHT
TONIGHT...FORECAST SOUNDINGS AND CROSSOVER TEMPERATURES SUGGEST SOME
TEMPORARY LOW STRATUS IN THE NORTHWEST. HRRR SIMULATION OF CEILINGS
SHOW LIFR CONDITIONS POSSIBLE AFTER 8Z THROUGH SUNRISE BUT IT MIGHT
END UP PRIMARILY WEST OF KINT AND KGSO. WILL LEAVE IN THE TAFS AS A
TEMPO GROUP FOR NOW.
LONG TERM: PRIMARILY VFR CONDITIONS SHOULD DOMINATE THE REGION
THROUGH THE MAJORITY OF THE LONG TERM.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...MWS
LONG TERM...MWS
AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
130 PM EDT THU SEP 5 2013
.SYNOPSIS...
A DRY COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION TONIGHT.
CANADIAN HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA ON FRIDAY WITH
GRADUAL WEAKENING THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM THURSDAY...
A WEAK COLD FRONT IS HUNG UP OVER THE COASTAL PLAIN THIS
MORNING...WITH DEWPOINTS ALONG AND TO THE EAST OF THE FRONT STILL IN
THE UPPER 60S AND LOWER 70S. WHILE THIS BOUNDARY CONTINUES TO PUSH
SLOWLY TO THE SOUTHEAST...MODIFIED NAM AND RAP SOUNDINGS SUGGEST
1000 J/KG OF MLCAPE WILL LINGER ALONG THE EASTERN PERIPHERY OF THE
CWA...AND THIS IS SOMEWHAT EVIDENT ALREADY IN THE SPC MESOANALYSIS.
HOWEVER..LOW LEVEL CONVERGENCE IS WEAK ALONG THE SURFACE FRONT AND A
WEAK 850MB TROUGH NOTED IN UPPER AIR ANALYSIS. THE SEABREEZE LOOKS
TO BE THE ONLY ENHANCEMENT FOR LIFT...AND RAP/HRRR PROGS SHOW THE
SEABREEZE ONLY BARELY REACHING SAMPSON COUNTY BY LATE AFTERNOON.
THUS...WILL LEAVE THE FORECAST FREE OF POPS FOR TODAY. OTHERWISE..
SKIES WILL BE MOSTLY SUNNY EXCEPT FOR OVER PORTIONS OF THE SOUTHERN
PIEDMONT WHERE THIN HIGH CLOUDS CONTINUE TO DRIFT SOUTHEAST IN THE
NORTHWESTERLY FLOW ALOFT. HIGHS IN THE UPPER 80S TO AROUND 90.
ANOTHER COLD FRONT TO OUR NORTH WILL SURGE SOUTH THIS EVENING AND
CROSS THE AREA OVERNIGHT...THOUGH WITH LITTLE MOISTURE TO WORK WITH.
LOWS TONIGHT WILL BE IN THE LOWER 60S NORTH TO MID/UPPER 60S
SOUTH.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 215 AM THURSDAY...
CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTH DOWN THE
MID-ATLANTIC SEABOARD...BECOMING CENTERED OVER THE AREA
BY SATURDAY MORNING. ASSOCIATED NORTHEASTERLY LOW-LEVEL MARITIME
FLOW WILL RESULT IN SCATTERED PATCHES OF POST-FRONTAL STRATUS FRIDAY
MORNING...AND PERHAPS A FAIRLY HEALTHY BROKEN STRATOCUMULUS DECK
BY THE AFTERNOON. COOLER AND LESS HUMID WITH HIGHS IN THE UPPER 70S
TO NEAR 80 NORTH TO MID 80S SOUTH.
THE STRATOCUMULUS MARINE LAYER LAYER WILL LIKELY GET TRAPPED
UNDERNEATH THE MID-LEVEL SUBSIDENCE INVERSION FRIDAY
EVENING/NIGHT...RESULTING IN PARTLY TO CLOUDY SKIES. LOWS IN THE MID
TO UPPER 50S NORTH TO LOWER/MID 60S SOUTH.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 245 AM THURSDAY...
OVERALL THE LONG TERM PERIOD WILL BE CHARACTERIZED BY MOSTLY DRY
CONDITIONS AS THE MAIN STORM TRACK REMAINS WELL NORTH OF THE REGION.
THE WEATHER ACROSS CENTRAL NC WILL BE DOMINATED BY SEVERAL
REINFORCING SURFACE HIGHS AND NORTHWEST FLOW ALOFT AS A BROAD TROUGH
REMAINS SITUATED JUST OFF THE EAST COAST...BEFORE AN UPPER LEVEL
RIDGE BUILDS EAST THROUGH THE MIDDLE OF NEXT WEEK.
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL WEAKEN AND BEGIN TO
SHIFT OFFSHORE LATE SATURDAY INTO EARLY SUNDAY...BUT WITH ONLY
MINIMAL MOISTURE RETURN...THE DRY CONDITIONS ARE EXPECTED TO PERSIST
THROUGH AT LEAST SUNDAY. THEN...ANOTHER FRONT IS PROGGED TO MOVE
ACROSS THE AREA ON LATE SUNDAY INTO MONDAY...WITH YET ANOTHER
RENEWED SURFACE HIGH RIDGING DOWN INTO THE REGION FOR EARLY NEXT
WEEK. AS THE FRONT CROSSES THE AREA ON MONDAY...THERE COULD BE SOME
ISOLATED ACTIVITY...ESPECIALLY ACROSS THE SOUTHERN TIER OF THE
FORECAST AREA...WHERE THE BEST MOISTURE CONTENT WILL RESIDE AND THE
TIMING OF THE FRONTAL PASSAGE WILL BE MOST FAVORABLE.
FOR THE REMAINDER OF THE WEEK...THE SURFACE HIGH WILL BE CENTERED
SLIGHTLY FURTHER TO THE NORTH THAN PREVIOUS ONES AND AS A
RESULT...MORE IN THE WAY OF EASTERLY FLOW IS EXPECTED AND THEREFORE
MOISTURE IS PROGGED TO GRADUALLY INCREASE THROUGH THE MIDDLE NEXT
WEEK. HOWEVER...THE EAST COAST TROUGH ALOFT IS FINALLY EXPECTED TO
BE REPLACED BY AN EASTWARD PROGRESSING UPPER LEVEL RIDGE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK...WHICH MAY WORK AGAINST ANY
CONVECTIVE DEVELOPMENT. WITH ALL OF THIS IN MIND...WITH MAINTAIN A
DRY FORECAST THROUGH THE REMAINDER OF THE LONG TERM PERIOD...BUT
THAT IS NOT TO SAY THERE COULD BE SOME ISOLATED DIURNAL TYPE
ACTIVITY. TEMPS WILL BE TIED TO THE MULTIPLE FRONTAL PASSAGES DURING
THE PERIOD...BUT WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL
THROUGHOUT THE ENTIRE PERIOD...EXCEPT FOR SATURDAY WHEN SLIGHTLY
BELOW NORMAL TEMPS ARE EXPECTED.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 130 PM THURSDAY...
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. MOISTURE ALONG
AND EAST OF A STALLED FRONT OVER THE COASTAL PLAIN IS LEADING TO A
SCATTERED CU FIELD WITH BASES AT 5K FT OR HIGHER TO THE SOUTH AND
EAST KRDU. THIS EVENING...A DRY COLD FRONT WILL PUSH SOUTH THROUGH
THE AREA...BETWEEN ROUGHLY 03-07Z...WITH WINDS TURNING TO
NORTHEASTERLY AND POSSIBLY GUSTING TO 15-20KT IMMEDIATELY BEHIND THE
FRONT. WINDS WILL REMAIN OUT OF THE NORTHEAST ON FRIDAY.
OUTLOOK...
OUTSIDE OF POCKETS OF SUB-VFR VSBYS IN THE EARLY MORNING HOURS...VFR
CONDITIONS ARE EXPECTED THROUGH THE WEEKEND. A COLD FRONT WILL
PUSH SOUTH INTO THE AREA BY MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...CBL/SMITH
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1015 AM EDT THU SEP 5 2013
.SYNOPSIS...
A DRY COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION TONIGHT.
CANADIAN HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA ON FRIDAY WITH
GRADUAL WEAKENING THROUGH THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM THURSDAY...
A WEAK COLD FRONT IS HUNG UP OVER THE COASTAL PLAIN THIS
MORNING...WITH DEWPOINTS ALONG AND TO THE EAST OF THE FRONT STILL IN
THE UPPER 60S AND LOWER 70S. WHILE THIS BOUNDARY CONTINUES TO PUSH
SLOWLY TO THE SOUTHEAST...MODIFIED NAM AND RAP SOUNDINGS SUGGEST
1000 J/KG OF MLCAPE WILL LINGER ALONG THE EASTERN PERIPHERY OF THE
CWA...AND THIS IS SOMEWHAT EVIDENT ALREADY IN THE SPC MESOANALYSIS.
HOWEVER..LOW LEVEL CONVERGENCE IS WEAK ALONG THE SURFACE FRONT AND A
WEAK 850MB TROUGH NOTED IN UPPER AIR ANALYSIS. THE SEABREEZE LOOKS
TO BE THE ONLY ENHANCEMENT FOR LIFT...AND RAP/HRRR PROGS SHOW THE
SEABREEZE ONLY BARELY REACHING SAMPSON COUNTY BY LATE AFTERNOON.
THUS...WILL LEAVE THE FORECAST FREE OF POPS FOR TODAY. OTHERWISE..
SKIES WILL BE MOSTLY SUNNY EXCEPT FOR OVER PORTIONS OF THE SOUTHERN
PIEDMONT WHERE THIN HIGH CLOUDS CONTINUE TO DRIFT SOUTHEAST IN THE
NORTHWESTERLY FLOW ALOFT. HIGHS IN THE UPPER 80S TO AROUND 90.
ANOTHER COLD FRONT TO OUR NORTH WILL SURGE SOUTH THIS EVENING AND
CROSS THE AREA OVERNIGHT...THOUGH WITH LITTLE MOISTURE TO WORK WITH.
LOWS TONIGHT WILL BE IN THE LOWER 60S NORTH TO MID/UPPER 60S
SOUTH.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 215 AM THURSDAY...
CANADIAN SURFACE HIGH PRESSURE WILL BUILD SOUTH DOWN THE
MID-ATLANTIC SEABOARD...BECOMING CENTERED OVER THE AREA
BY SATURDAY MORNING. ASSOCIATED NORTHEASTERLY LOW-LEVEL MARITIME
FLOW WILL RESULT IN SCATTERED PATCHES OF POST-FRONTAL STRATUS FRIDAY
MORNING...AND PERHAPS A FAIRLY HEALTHY BROKEN STRATOCUMULUS DECK
BY THE AFTERNOON. COOLER AND LESS HUMID WITH HIGHS IN THE UPPER 70S
TO NEAR 80 NORTH TO MID 80S SOUTH.
THE STRATOCUMULUS MARINE LAYER LAYER WILL LIKELY GET TRAPPED
UNDERNEATH THE MID-LEVEL SUBSIDENCE INVERSION FRIDAY
EVENING/NIGHT...RESULTING IN PARTLY TO CLOUDY SKIES. LOWS IN THE MID
TO UPPER 50S NORTH TO LOWER/MID 60S SOUTH.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 245 AM THURSDAY...
OVERALL THE LONG TERM PERIOD WILL BE CHARACTERIZED BY MOSTLY DRY
CONDITIONS AS THE MAIN STORM TRACK REMAINS WELL NORTH OF THE REGION.
THE WEATHER ACROSS CENTRAL NC WILL BE DOMINATED BY SEVERAL
REINFORCING SURFACE HIGHS AND NORTHWEST FLOW ALOFT AS A BROAD TROUGH
REMAINS SITUATED JUST OFF THE EAST COAST...BEFORE AN UPPER LEVEL
RIDGE BUILDS EAST THROUGH THE MIDDLE OF NEXT WEEK.
HIGH PRESSURE OVER THE AREA ON SATURDAY WILL WEAKEN AND BEGIN TO
SHIFT OFFSHORE LATE SATURDAY INTO EARLY SUNDAY...BUT WITH ONLY
MINIMAL MOISTURE RETURN...THE DRY CONDITIONS ARE EXPECTED TO PERSIST
THROUGH AT LEAST SUNDAY. THEN...ANOTHER FRONT IS PROGGED TO MOVE
ACROSS THE AREA ON LATE SUNDAY INTO MONDAY...WITH YET ANOTHER
RENEWED SURFACE HIGH RIDGING DOWN INTO THE REGION FOR EARLY NEXT
WEEK. AS THE FRONT CROSSES THE AREA ON MONDAY...THERE COULD BE SOME
ISOLATED ACTIVITY...ESPECIALLY ACROSS THE SOUTHERN TIER OF THE
FORECAST AREA...WHERE THE BEST MOISTURE CONTENT WILL RESIDE AND THE
TIMING OF THE FRONTAL PASSAGE WILL BE MOST FAVORABLE.
FOR THE REMAINDER OF THE WEEK...THE SURFACE HIGH WILL BE CENTERED
SLIGHTLY FURTHER TO THE NORTH THAN PREVIOUS ONES AND AS A
RESULT...MORE IN THE WAY OF EASTERLY FLOW IS EXPECTED AND THEREFORE
MOISTURE IS PROGGED TO GRADUALLY INCREASE THROUGH THE MIDDLE NEXT
WEEK. HOWEVER...THE EAST COAST TROUGH ALOFT IS FINALLY EXPECTED TO
BE REPLACED BY AN EASTWARD PROGRESSING UPPER LEVEL RIDGE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK...WHICH MAY WORK AGAINST ANY
CONVECTIVE DEVELOPMENT. WITH ALL OF THIS IN MIND...WITH MAINTAIN A
DRY FORECAST THROUGH THE REMAINDER OF THE LONG TERM PERIOD...BUT
THAT IS NOT TO SAY THERE COULD BE SOME ISOLATED DIURNAL TYPE
ACTIVITY. TEMPS WILL BE TIED TO THE MULTIPLE FRONTAL PASSAGES DURING
THE PERIOD...BUT WILL GENERALLY BE NEAR TO SLIGHTLY ABOVE NORMAL
THROUGHOUT THE ENTIRE PERIOD...EXCEPT FOR SATURDAY WHEN SLIGHTLY
BELOW NORMAL TEMPS ARE EXPECTED.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AS OF 720 AM THURSDAY...
24 HOUR TAF PERIOD:
CLEAR SKIES AND CALM WINDS WILL SUPPORT AREAS OF FOG
OVERNIGHT...ESPECIALLY ACROSS CENTRAL AND EASTERN PORTIONS OF THE
STATE WHERE LOW-LEVEL REMAINS HIGH IN CLOSER PROXIMITY TO A
DISSIPATING STALLED SURFACE FRONT. AFTER DAYBREAK...EXPECT
CONDITIONS TO IMPROVE BACK TO VFR (BY APPROX 12-13Z) FOR THE
REMAINDER OF THE TAF PERIOD WITH LIGHT NORTH-NORTHWESTERLY WINDS
THROUGHOUT THE DAY. A SECONDARY DRY COLD FRONT WILL PUSH SOUTH
THROUGH THE AREA BETWEEN 00 TO 09Z FRIDAY. COULD SEE A BRIEF 1-2HR
PERIOD OF NELY WIND GUSTS IMMEDIATELY BEHIND THE FRONT...OTHERWISE
NO SIGNIFICANT WEATHER IS EXPECTED.
LOOKING AHEAD:
ASIDE FROM SOME EARLY MORNING FOG..A DRY BELOW NORMAL PWAT AIRMASS
WITH HIGH PRES AT THE SURFACE WILL RESULT IN PREDOMINATELY VFR
CONDITIONS THROUGH THE WEEKEND. ANOTHER DRY BACK-DOOR COLD FRONTAL
WILL PUSH SOUTH THROUGH THE AREA SUNDAY NIGHT AND INTO EARLY MONDAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CBL
NEAR TERM...CBL/SMITH
SHORT TERM...CBL
LONG TERM...KRR
AVIATION...CBL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
134 PM CDT THU SEP 5 2013
.UPDATE...
ISSUED AT 1247 PM CDT THU SEP 5 2013
EARLY AFTERNOON UPDATE FOR MIDDAY TEMPERATURE AND SKY COVER
TRENDS...OTHERWISE CURRENT FORECAST IS ON TRACK.
THE MAIN FORECAST ISSUE FOR TONIGHT THROUGH FRIDAY NIGHT IS THE
POTENTIAL FOR ANOTHER ROUND OF THUNDERSTORM ACTIVITY AND THE
ASSOCIATED THREAT FOR ISOLATED SEVERE WEATHER. IN THE NEAR
TERM...OPTED FOR A DRY FORECAST TONIGHT WITH LITTLE IN THE WAY OF
FORCING EXPECTED. ON FRIDAY...INSTABILITY AND MOISTURE WILL BE ON
THE INCREASE. A SURFACE TROUGH IS EXPECTED TO STRETCH ACROSS
WESTERN ND AND SYNOPTIC SCALE FORCING SHOULD BE ON THE INCREASE
DURING THE LATE AFTERNOON/EVENING HOURS AS SHORT WAVE ENERGY RIDES
UP THE UPPER RIDGE. THE ENTIRE FORECAST AREA IS IN THE 5 PERCENT
RISK AREA FOR ISOLATED SEVERE STORMS. HAVE SPEEDED UP THE TIMING
OF THE AFTERNOON POPS IN A NOD TO THE FASTER SOLUTIONS...AND MODEL
CONSENSUS SUPPORTS AN INCREASE IN POPS FOR FRIDAY
NIGHT...ESPECIALLY WEST. A LIMITING FACTOR FOR SEVERE WEATHER WILL
BE RELATIVELY MODEST DEEP LAYER SHEAR...BUT UNDOUBTEDLY THERE WILL
BE AT LEAST A FEW STORMS TO MONITOR.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1017 AM CDT THU SEP 5 2013
EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE PERIOD WITH A
LIGHT SOUTHEAST WIND UNDER 10 KTS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...RP KINNEY
SHORT TERM...LTH
LONG TERM...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1031 AM CDT THU SEP 5 2013
.UPDATE...
ISSUED AT 1017 AM CDT THU SEP 5 2013
UPDATE TO REMOVE POPS ACROSS THE WEST FOR THE LATE MORNING AS THE
ISOLATED THUNDERSTORMS HAVE DISSIPATED. OTHERWISE...EXPECT A
MOSTLY SUNNY SKY TODAY WITH QUIET WEATHER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1017 AM CDT THU SEP 5 2013
EXPECT VFR CONDITIONS AT ALL TAF SITES THROUGH THE PERIOD WITH A
LIGHT SOUTHEAST WIND UNDER 10 KTS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE/AVIATION...RP KINNEY
SHORT TERM...LTH
LONG TERM...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT THU SEP 5 2013
.UPDATE...
ISSUED AT 636 AM CDT THU SEP 5 2013
ONGOING CONVECTION OVER EASTERN MONTANA IS DISORGANIZED AND VERY
SLOW MOVING. IT MAY NOT EVEN HOLD TOGETHER TO MAKE IT TO THE MT/ND
BORDER. NEVERTHELESS...MAINTAINED SLIGHT CHANCE POPS WEST THIS
MORNING. A DRYING TREND IS STILL EXPECTED THIS AFTERNOON AS AN
UPPER WAVE MOVES EAST OF THE CWA.
OTHERWISE...NO MAJOR CHANGES WERE REQUIRED TO THE ONGOING
FORECAST. ADJUSTED THE HOURLY TEMP/WIND/DEWPOINT GRIDS BASED ON
CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 636 AM CDT THU SEP 5 2013
VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 12Z TAF
PERIOD. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS
WESTERN NORTH DAKOTA DURING THE EARLY MORNING HOURS.
HOWEVER...UNCERTAINTY REMAINS TOO GREAT TO INCLUDE ANY PREVAILING
THUNDERSTORM OR SHOWER GROUP IN THE TAFS. SO HAVE INCLUDED VCSH TO
KDIK AND KISN TO INDICATE POSSIBLE TIMING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...TM
SHORT TERM...LTH
LONG TERM...TM
AVIATION...LTH
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 AM CDT THU SEP 5 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS
PRECIPITATION CHANCES.
RADAR IMAGERY AT 08Z SHOWS ONGOING SHOWER ACTIVITY ACROSS CENTRAL
NORTH DAKOTA...WITH MORE WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY
OVER THE BLACK HILLS REGION OF SOUTH DAKOTA...ASSOCIATED WITH A
WEAK UPPER LEVEL IMPULSE MOVING OVER THE AREA THIS MORNING. THERE
IS A BIT OF UNCERTAINTY IN THE PRECIP FORECAST THROUGH EARLY
AFTERNOON...AS THE 00Z GFS/ECWMF ARE MORE ROBUST IN AREAL EXTENT
OF SHOWER/THUNDERSTORM COVERAGE VERSUS THE 00Z NAM/GEM AND LATEST
RUNS OF THE HRRR AND RAP...WHICH ARE MORE SPOTTY WITH COVERAGE.
CONSEQUENTLY...HAVE USED A BLEND OF GUIDANCE...LIMITING POPS TO
SLIGHT CHANCE. LIGHTNING STRIKES HAVE BEEN FAR AND FEW BETWEEN
WITH ONGOING SHOWERS...SO HAVE REMOVED THE MENTION OF THUNDER IN
WX GRIDS FOR ALL EXCEPT ACROSS THE SOUTHWEST AND FAR WEST WHERE
CAPE MAY BE MORE PLENTIFUL. IN ADDITION...HAVE INCLUDED THE
MENTION OF SPRINKLES THROUGH LATE MORNING TO REFLECT ONGOING
ACTIVITY. SHOWERS/THUNDERSTORMS SHOULD COME TO AN END BY 18Z ONCE
THE WEAK IMPULSE MOVES INTO WESTERN MINNESOTA.
WARMER TEMPERATURES ARE EXPECTED ACROSS THE AREA TODAY AS A RIDGE
AND WARMER H850 TEMPERATURES MOVE OVERHEAD. THIS WILL RESULT IN
AFTERNOON TEMPERATURES CLIMBING INTO THE UPPER 80S AND LOWER
90S...AND OVERNIGHT TEMPERATURES COOLING ONLY INTO THE 60S.
DEWPOINTS WILL ALSO BE ON THE RISE...THOUGH HEAT INDEX VALUES
SHOULD REMAIN IN THE 90S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU SEP 5 2013
THE MAIN FORECAST CHALLENGE FOR THE EXTENDED WILL BE THE AREAL
EXTENT AND COVERAGE OF PRECIPITATION CHANCES THIS WEEKEND. GIVEN THE
MODEL TO MODEL AND RUN TO RUN INCONSISTENCIES...CONTINUED TO FOLLOW
A BLENDED APPROACH FOR THE EXTENDED PERIOD FORECAST.
EARLY IN THE PERIOD...THE MEDIUM RANGE MODELS CONTINUE TO STRUGGLE
WITH THE EXACT TIMING AND LOCATION OF SHORTWAVES EJECTING FROM AN
UPPER LOW PROGGED TO REMAIN OVER THE PACIFIC NORTHWEST THROUGH
SATURDAY. FOR NOW CONTINUED TO FORECAST AN INCREASING POP TREND WEST
AND CENTRAL THROUGH SATURDAY AND KEPT THE EAST (TURTLE MOUNTAIN
SOUTH TO THE JAMES RIVER VALLEY) DRY THROUGH EARLY SUNDAY MORNING.
AS THE UPPER LOW FINALLY PUSHES INTO MONTANA...THUNDERSTORM CHANCES
SHOULD INCREASE ACROSS THE ENTIRE STATE SUNDAY AND SUNDAY NIGHT.
GIVEN THE EXPECTED POSITION OF THE LOW AND ATTENDANT DEEP LAYER
SHEAR/INSTABILITY PARAMETERS...SEVERE WEATHER COULD BE POSSIBLE
SUNDAY AFTERNOON/EVENING. WILL CONTINUE TO HIGHLIGHT THIS
POSSIBILITY IN THE HWO.
THE LATEST GFS/ECMWF/GEM ALL DIFFER WITH RESPECT TO THE TIMING OF
THE LOW PIVOTING ACROSS NORTH DAKOTA AND SUBSEQUENTLY DRY CONDITIONS
FILTERING INTO THE REGION. THE LATEST ECMWF IS NOW MORE PROGRESSIVE
WITH THIS FEATURE AND PIVOTS IT THROUGH THE REGION MONDAY. THE GFS
IS ABOUT 12 HOURS SLOWER WHEREAS THE GEM IS AN AVERAGE OF THE TWO.
FOR NOW KEPT POPS IN AREAWIDE MONDAY AND FORECAST A DRYING TREND
TUESDAY THROUGH WEDNESDAY AS HIGH PRESSURE BUILDS OVER THE ROCKIES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 106 AM CDT THU SEP 5 2013
VFR CONDITIONS WILL PREVAIL ACROSS ALL TAF SITES FOR THE 06Z TAF
PERIOD. SCATTERED SHOWERS CURRENTLY OVER THE NORTH CENTRAL PART OF
THE STATE WILL CONTINUE TO MOVE EAST. ADDITIONAL SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS WESTERN NORTH DAKOTA
OVER THE NEXT FEW HOURS. HOWEVER...UNCERTAINTY REMAINS TOO GREAT
TO INCLUDE ANY PREVAILING THUNDERSTORM OR SHOWER GROUP IN THE TAFS. SO
HAVE INCLUDED VCSH TO KDIK...KMOT...AND KBIS TO INDICATE POSSIBLE
TIMING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...LTH
LONG TERM...TM
AVIATION...LTH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
641 AM EDT THU SEP 5 2013
.SYNOPSIS...
A MOISTURE-STARVED COLD FRONT WILL MOVE SOUTH THROUGH THE OHIO
VALLEY TODAY. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD IN FOR
FRIDAY...WITH RELATIVELY COOL AND DRY CONDITIONS. AS THE HIGH
MOVES OFF TO THE EAST...A GRADUAL RETURN TO WARMER TEMPERATURES
WILL OCCUR OVER THE WEEKEND AND INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COLD FRONT IS CURRENTLY IDENTIFIABLE (BY WIND SHIFT) NEAR THE
BORDER WITH MICHIGAN...AND IT WILL BE MAKING ITS WAY SOUTH INTO
THE ILN CWA TODAY. A WIDE SUITE OF MODEL SOLUTIONS REFUSES TO
PRODUCE ANY QPF OUTPUT WITH THIS FEATURE...OWING MAINLY TO THE
DRY AIR MASS THAT THE FRONT IS MOVING INTO (PWAT VALUES AT OR
BELOW 1 INCH). THERE SHOULD BE SOME RESPONSE IN TERMS OF
STRATOCUMULUS DEVELOPMENT...SO SKY GRIDS NEAR THE FRONT INCREASE
TO AROUND 50 PERCENT. OTHERWISE...ASIDE FROM SOME HIGH
CLOUDS...SKIES SHOULD BE MOSTLY CLEAR.
THE TIMING OF THE TEMPERATURE TRACE TODAY LOOKS TO BE ROUGHLY
DIURNAL...EVEN AS THE FRONT MOVES THROUGH THE REGION. THE NORTH
HALF OF THE CWA MAY PEAK OUT SLIGHTLY EARLIER THAN NORMAL AND HOLD
SOMEWHAT STEADY GOING INTO THE AFTERNOON. THERE WILL BE A NNE-TO-
SSW GRADIENT...WITH THE WARMEST TEMPS IN SOME OF THE NORTHERN
KENTUCKY ILN COUNTIES. THE RAP MODEL HAS BEEN IGNORED FOR
TODAY...AS IT MIXES THROUGH 800MB AND PRODUCES TEMPERATURE VALUES
FAR TOO HIGH. OTHERWISE...THE REST OF THE MAIN SUITE OF MODELS IS
IN FAIRLY GOOD AGREEMENT ON TEMPS...WITH LOWER 80S IN THE SW AND
MID 70S IN THE NE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
ALTHOUGH THE SOUTHWARD-MOVING COLD FRONT WILL ALMOST CERTAINLY
COME THROUGH DRY (THOUGH A PATCH OR TWO OF TRACE PRECIP IS NOT
TOTALLY OUT OF THE REALM OF POSSIBILITY IN THE SOUTHERN CWA IN THE
LATE AFTERNOON)...THERE WILL BE A MARKED WIND SHIFT TO THE
NNE. THIS WILL BRING SOME STRONG COLD ADVECTION...SETTING THINGS
UP FOR A COOL FORECAST FOR TONIGHT. THE CENTER OF THE HIGH WILL BE
OVER PENNSYLVANIA...SO SOME LIGHT EASTERLY FLOW SHOULD STILL BE
PRESENT...MAKING THE RADIATIONAL COOLING CONDITIONS
NOT-QUITE-IDEAL. HOWEVER...THE DRYING AIR MASS AND CLEAR SKIES
WILL EASILY BE ENOUGH TO ALLOW TEMPS INTO THE LOWER 50S...WITH
UPPER 40S EXPECTED IN OUTLYING AREAS.
THE HIGH WILL STILL BE CLOSE ENOUGH TO INFLUENCE THE WEATHER
FRIDAY...WITH ONLY A SLIGHT CLOCKWISE TURN IN THE WIND
DIRECTION...AND NO REAL SIGN OF SURFACE WARM ADVECTION QUITE YET.
ON THE OTHER HAND...TEMPERATURES WILL BEGIN WARMING SLIGHTLY
ALOFT...LEADING TO AN INTERESTING FORECAST CHALLENGE. MODEL
SOUNDINGS ARE EXTREMELY SHALLOW IN MIXING FOR FRIDAY AFTERNOON
(GFS/NAM AT KCVG BOTH SHOWING ONLY AROUND 900MB-875MB).
HOWEVER...THE WARMING AIR JUST OFF THE SURFACE WILL MEAN THAT ONLY
A SMALL CHANGE IN MIXING HEIGHT WOULD CAUSE A MODERATE CHANGE IN
REALIZED SURFACE HIGH TEMPERATURES. FORECAST TEMPS ARE CLOSE TO A
BLEND OF THE RAW GFS/NAM...AND SLIGHTLY LOWER THAN THE ADJUSTED
MAV/MET GUIDANCE NUMBERS. HOWEVER...THOSE GUIDANCE NUMBERS WOULD
END UP LOOKING MORE CORRECT IF MIXING DOES GET HIGHER THAN
CURRENTLY ANTICIPATED.
A VEERING OF SURFACE WINDS WILL CONTINUE INTO THE WEEKEND...AS THE
SURFACE HIGH MOVES SOUTHEAST INTO THE DELMARVA REGION. AS THIS
OCCURS...RIDGING WILL BEGIN TO BUILD IN ALOFT. THIS WILL PUT THE
CWA IN A REGIME OF NORTHWEST FLOW ALOFT (EVENTUALLY SPILLING IN
SOME CLOUDS) AND SW FLOW AT THE SURFACE (WITH TEMPERATURES AND
DEWPOINTS BEGINNING TO RISE AGAIN). ANOTHER FRONT WILL MAKE ITS
WAY SOUTHWARD INTO THE OHIO VALLEY ON SATURDAY NIGHT INTO
SUNDAY...AND THOUGH IT ALSO LOOKS LIKE A FAIRLY DRY FRONT...THERE
IS ENOUGH MOISTURE TO SUPPORT SOME PRECIPITATION POTENTIAL. 00Z
GFS/ECMWF RUNS BOTH DEPICT THAT HIGH PRESSURE OVER THE GREAT LAKES
WILL VERY BRIEFLY ENTER THE PICTURE OVER THE OHIO VALLEY ON SUNDAY
NIGHT AND MONDAY...BEFORE RIDGING MOVES EAST AGAIN AND PUTS THE
CWA INTO A WARMER AND WETTER PATTERN FOR THE MIDDLE OF THE WEEK.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AFTER SUNDAY...THE UPPER HIGH BUILDS AND NORTHWEST FLOW BECOMES
MORE WESTERLY IN OHIO VALLEY. SURFACE FLOW INCREASES FROM THE
SOUTHWEST ON TUESDAY. AN ISOLATED POPUP SHOWER COULD OCCUR DURING
THE HEATING OF THE DAY MONDAY AND AGAIN WITH THE INCREASED
MOISTURE WORKING IN TUESDAY...BUT THE LOW 20% COVERAGE WILL KEEP
MENTION OF SHOWERS OUT OF THE FORECAST.
UPPER RIDGE BREAKS DOWN AND A TROUGH APPROACHES FROM THE NORTHWEST
ON WEDNESDAY. IT ALSO COMES WITH A SURFACE COLD FRONT AND IS THE
FAVORED MECHANISM FOR THUNDERSTORM DEVELOPMENT IN THE EXTENDED
PERIOD.
HIGHS WILL REMAIN IN THE 80S AND COULD APPROACH 90 WITH ENOUGH
SUNSHINE. LOWS SHOULD STAY IN THE 60S BUT SOME UPPER 50S ARE
POSSIBLE IN CENTRAL OHIO SAT NIGHT AND FOR MOST AREAS SUN NIGHT WITH
DRIER AIR. THEY WILL PUSH BACK INTO THE MID TO UPPER 60S FOR THE
REMAINDER OF NEXT WEEK WITH THE RETURN OF SOUTHERLY FLOW.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
A MOISTURE STARVED COLD FRONT WILL DROP SOUTH THROUGH THE TAF
SITES THIS MORNING. ANY MIST/FOG EARLY THIS MORNING SHOULD BE GONE
BETWEEN 13Z AND 14Z DUE TO MIXING AND/OR A WIND SHIFT TO THE
NORTH.
FOR LATER TODAY...THE FRONT WILL CONTINUE SOUTH OF THE OHIO RIVER.
SOME POST FRONTAL MOISTURE AND CAA WILL RESULT IN DIURNALLY DRIVEN
SCT-BKN CUMULUS CLOUDS.
FOR TONIGHT...A SPRAWLING AREA OF HIGH PRESSURE WILL BUILD
SOUTH INTO THE NEW ENGLAND...MID ATLANTIC AND OHIO VALLEY REGION.
SKIES WILL BECOME MOSTLY CLEAR AS WINDS SHIFT TO THE EAST/NORTHEAST...
ALLOWING DRIER AIR TO FILTER BACK INTO THE AREA. SOME SHALLOW
GROUND FOG MAY BE POSSIBLE AT KILN AND RIVER FOG AT KLUK LATE
TONIGHT.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...FRANKS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
400 AM EDT THU SEP 5 2013
.SYNOPSIS...
A MOISTURE-STARVED COLD FRONT WILL MOVE SOUTH THROUGH THE OHIO
VALLEY TODAY. BEHIND THE FRONT...HIGH PRESSURE WILL BUILD IN FOR
FRIDAY...WITH RELATIVELY COOL AND DRY CONDITIONS. AS THE HIGH
MOVES OFF TO THE EAST...A GRADUAL RETURN TO WARMER TEMPERATURES
WILL OCCUR OVER THE WEEKEND AND INTO NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A COLD FRONT IS CURRENTLY IDENTIFIABLE (BY WIND SHIFT) NEAR THE
BORDER WITH MICHIGAN...AND IT WILL BE MAKING ITS WAY SOUTH INTO
THE ILN CWA TODAY. A WIDE SUITE OF MODEL SOLUTIONS REFUSES TO
PRODUCE ANY QPF OUTPUT WITH THIS FEATURE...OWING MAINLY TO THE
DRY AIR MASS THAT THE FRONT IS MOVING INTO (PWAT VALUES AT OR
BELOW 1 INCH). THERE SHOULD BE SOME RESPONSE IN TERMS OF
STRATOCUMULUS DEVELOPMENT...SO SKY GRIDS NEAR THE FRONT INCREASE
TO AROUND 50 PERCENT. OTHERWISE...ASIDE FROM SOME HIGH
CLOUDS...SKIES SHOULD BE MOSTLY CLEAR.
THE TIMING OF THE TEMPERATURE TRACE TODAY LOOKS TO BE ROUGHLY
DIURNAL...EVEN AS THE FRONT MOVES THROUGH THE REGION. THE NORTH
HALF OF THE CWA MAY PEAK OUT SLIGHTLY EARLIER THAN NORMAL AND HOLD
SOMEWHAT STEADY GOING INTO THE AFTERNOON. THERE WILL BE A NNE-TO-
SSW GRADIENT...WITH THE WARMEST TEMPS IN SOME OF THE NORTHERN
KENTUCKY ILN COUNTIES. THE RAP MODEL HAS BEEN IGNORED FOR
TODAY...AS IT MIXES THROUGH 800MB AND PRODUCES TEMPERATURE VALUES
FAR TOO HIGH. OTHERWISE...THE REST OF THE MAIN SUITE OF MODELS IS
IN FAIRLY GOOD AGREEMENT ON TEMPS...WITH LOWER 80S IN THE SW AND
MID 70S IN THE NE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
ALTHOUGH THE SOUTHWARD-MOVING COLD FRONT WILL ALMOST CERTAINLY
COME THROUGH DRY (THOUGH A PATCH OR TWO OF TRACE PRECIP IS NOT
TOTALLY OUT OF THE REALM OF POSSIBILITY IN THE SOUTHERN CWA IN THE
LATE AFTERNOON)...THERE WILL BE A MARKED WIND SHIFT TO THE
NNE. THIS WILL BRING SOME STRONG COLD ADVECTION...SETTING THINGS
UP FOR A COOL FORECAST FOR TONIGHT. THE CENTER OF THE HIGH WILL BE
OVER PENNSYLVANIA...SO SOME LIGHT EASTERLY FLOW SHOULD STILL BE
PRESENT...MAKING THE RADIATIONAL COOLING CONDITIONS
NOT-QUITE-IDEAL. HOWEVER...THE DRYING AIR MASS AND CLEAR SKIES
WILL EASILY BE ENOUGH TO ALLOW TEMPS INTO THE LOWER 50S...WITH
UPPER 40S EXPECTED IN OUTLYING AREAS.
THE HIGH WILL STILL BE CLOSE ENOUGH TO INFLUENCE THE WEATHER
FRIDAY...WITH ONLY A SLIGHT CLOCKWISE TURN IN THE WIND
DIRECTION...AND NO REAL SIGN OF SURFACE WARM ADVECTION QUITE YET.
ON THE OTHER HAND...TEMPERATURES WILL BEGIN WARMING SLIGHTLY
ALOFT...LEADING TO AN INTERESTING FORECAST CHALLENGE. MODEL
SOUNDINGS ARE EXTREMELY SHALLOW IN MIXING FOR FRIDAY AFTERNOON
(GFS/NAM AT KCVG BOTH SHOWING ONLY AROUND 900MB-875MB).
HOWEVER...THE WARMING AIR JUST OFF THE SURFACE WILL MEAN THAT ONLY
A SMALL CHANGE IN MIXING HEIGHT WOULD CAUSE A MODERATE CHANGE IN
REALIZED SURFACE HIGH TEMPERATURES. FORECAST TEMPS ARE CLOSE TO A
BLEND OF THE RAW GFS/NAM...AND SLIGHTLY LOWER THAN THE ADJUSTED
MAV/MET GUIDANCE NUMBERS. HOWEVER...THOSE GUIDANCE NUMBERS WOULD
END UP LOOKING MORE CORRECT IF MIXING DOES GET HIGHER THAN
CURRENTLY ANTICIPATED.
A VEERING OF SURFACE WINDS WILL CONTINUE INTO THE WEEKEND...AS THE
SURFACE HIGH MOVES SOUTHEAST INTO THE DELMARVA REGION. AS THIS
OCCURS...RIDGING WILL BEGIN TO BUILD IN ALOFT. THIS WILL PUT THE
CWA IN A REGIME OF NORTHWEST FLOW ALOFT (EVENTUALLY SPILLING IN
SOME CLOUDS) AND SW FLOW AT THE SURFACE (WITH TEMPERATURES AND
DEWPOINTS BEGINNING TO RISE AGAIN). ANOTHER FRONT WILL MAKE ITS
WAY SOUTHWARD INTO THE OHIO VALLEY ON SATURDAY NIGHT INTO
SUNDAY...AND THOUGH IT ALSO LOOKS LIKE A FAIRLY DRY FRONT...THERE
IS ENOUGH MOISTURE TO SUPPORT SOME PRECIPITATION POTENTIAL. 00Z
GFS/ECMWF RUNS BOTH DEPICT THAT HIGH PRESSURE OVER THE GREAT LAKES
WILL VERY BRIEFLY ENTER THE PICTURE OVER THE OHIO VALLEY ON SUNDAY
NIGHT AND MONDAY...BEFORE RIDGING MOVES EAST AGAIN AND PUTS THE
CWA INTO A WARMER AND WETTER PATTERN FOR THE MIDDLE OF THE WEEK.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
AFTER SUNDAY...THE UPPER HIGH BUILDS AND NORTHWEST FLOW BECOMES
MORE WESTERLY IN OHIO VALLEY. SURFACE FLOW INCREASES FROM THE
SOUTHWEST ON TUESDAY. AN ISOLATED POPUP SHOWER COULD OCCUR DURING
THE HEATING OF THE DAY MONDAY AND AGAIN WITH THE INCREASED
MOISTURE WORKING IN TUESDAY...BUT THE LOW 20% COVERAGE WILL KEEP
MENTION OF SHOWERS OUT OF THE FORECAST.
UPPER RIDGE BREAKS DOWN AND A TROUGH APPROACHES FROM THE NORTHWEST
ON WEDNESDAY. IT ALSO COMES WITH A SURFACE COLD FRONT AND IS THE
FAVORED MECHANISM FOR THUNDERSTORM DEVELOPMENT IN THE EXTENDED
PERIOD.
HIGHS WILL REMAIN IN THE 80S AND COULD APPROACH 90 WITH ENOUGH
SUNSHINE. LOWS SHOULD STAY IN THE 60S BUT SOME UPPER 50S ARE
POSSIBLE IN CENTRAL OHIO SAT NIGHT AND FOR MOST AREAS SUN NIGHT WITH
DRIER AIR. THEY WILL PUSH BACK INTO THE MID TO UPPER 60S FOR THE
REMAINDER OF NEXT WEEK WITH THE RETURN OF SOUTHERLY FLOW.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
A MOISTURE STARVED COLD FRONT WILL DROP SOUTH FROM THE SOUTHERN
GREAT LAKES TO THE OHIO RIVER VALLEY BY MORNING. AHEAD OF THE
FRONT...ENOUGH LOW LEVEL MOISTURE AND MAINLY CLEAR SKIES/LIGHT
WINDS MAY ALLOW FOR SOME MVFR MIST TO FORM AT KILN AND KLUK WITH
PERHAPS A PERIOD OF IFR VSBYS AT KLUK BEFORE FRONTAL PASSAGE.
OTHERWISE...THE FRONT WILL BE MARKED BY A WIND SHIFT TO THE NORTH
ALONG WITH A FEW-SCT STRATOCUMULUS CLOUDS NEAR THE NORTHERN TAF
SITES.
FOR LATER TODAY...THE FRONT WILL CONTINUE SOUTH OF THE OHIO RIVER.
SOME POST FRONTAL MOISTURE AND CAA WILL RESULT IN DIURNALLY DRIVEN
SCT-BKN CUMULUS CLOUDS.
FOR TONIGHT...A SPRAWLING AREA OF HIGH PRESSURE WILL BUILD
SOUTH INTO THE NEW ENGLAND...MID ATLANTIC AND OHIO VALLEY REGION.
SKIES WILL BECOME MOSTLY CLEAR AS WINDS SHIFT TO THE EAST/NORTHEAST...
ALLOWING DRIER AIR TO FILTER BACK INTO THE AREA.
OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...FRANKS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION...UPDATE
NWS PORTLAND OR
211 PM PDT THU SEP 5 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT. LOCALIZED HEAVY RAINFALL IS EXPECTED
THROUGH FRIDAY MORNING AS THE LOW MOVES OVER THE AREA.SHOWERS WILL
DECREASE FRIDAY EVENING TO THE SOUTH BUT LINGER ACROSS THE NORTH
THROUGH SATURDAY MORNING. HIGH PRESSURE WILL BUILD BEHIND
THE LOW WITH DRIER WEATHER EXPECTED BY SUNDAY. WARMER WEATHER IS
EXPECTED EARLY NEXT WEEK.
&&
.SHORT TERM....CONVECTIVE BANDS CIRCULATING AROUND AN UPPER LOW ARE
MOVING OVER LANE COUNTY EARLY THIS AFTERNOON...WITH THUNDERSTORMS
PRODUCING ABUNDANT LIGHTNING AND HEAVY RAIN. WE HAVE RECEIVED REPORTS
OF POWER OUTAGES...LOCALIZED PONDING OF WATER ON ROADWAYS WITH THESE
STORMS SO FAR...AS WELL AS ONE REPORT OF SMALL HAIL.
THE LOW CENTER IS CURRENTLY AROUND 60 MILES OFF OF THE SOUTHERN
OREGON COAST AND WILL BE PUSHING INLAND ACROSS NW OREGON THIS
AFTERNOON AND EVENING. AS IT MOVES INLAND SHOWERS AND THUNDERSTORMS
WILL SHIFT NORTHWARD. THE HRRR MODELED COMPOSITE REFLECTIVITIES HAS
BEEN DOING A GREAT JOB OF FORECASTING THE LOCATION OF RAIN THIS
MORNING AND SHOWS THE MAIN RAIN BAND WILL BE CENTERED OVER THE CENTRAL
WILLAMETTE VALLEY BY 4PM THIS EVENING AND CENTERED OVER THE PORTLAND
METRO AREA BY 7 PM. THIS BAND SEEMS TO THIN AND FALL APART AS IT
MOVES NORTH...AND EXPECT THUNDERSTORM COVERAGE TO LESSEN.
HOWEVER...SHOWERS WRAPPING AROUND THE LOW WILL EXPAND OVER THE AREA
LATER TONIGHT AS THE LOW MOVES FURTHER TO THE NE...AND LOCALIZED
HEAVY RAIN WILL CONTINUE THROUGH THE NIGHT.
WRAP AROUND SHOWERS WILL CONTINUE FRIDAY AS THE LOW SHIFTS NE OF THE
AREA...MAINLY NORTH OF SALEM. THE MODELS HAVE SLOWED THE TIMING OF
THE RIDGE BUILDING OVER THE AREA AND DELAYING DRYING OVER THE AREA.
SOUTHERN AREAS WILL DRY SATURDAY...BUT SHOWERS MAY LINGER ACROSS THE
SOUTHERN WASHINGTON THROUGH SATURDAY MORNING.
.LONG TERM...SUNDAY THROUGH WEDNESDAY NIGHT...A STRONG LATE SEASON
RIDGE WILL BUILD INTO THE PAC NW SUNDAY THROUGH TUESDAY HOLD THROUGH
LATE NEXT WEEK. THE LATEST MEDIUM RANGE MODELS INDICATE THAT 500 MB
HEIGHTS WILL NEAR 590 DM OVER THE REGION...WITH 850 MB TEMPS NEAR 20C
BY TUE OR WED. MEANWHILE A THERMAL INDUCED SURFACE TROUGH IS PROGGED
TO BUILD ALONG THE COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW
LEVEL FLOW. THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL
SEE A SIGNIFICANT WARM UP NEXT WEEK. THE OFFSHORE FLOW PATTERN WOULD
ALSO ALLOW THE COAST TO SEE SOME OF THEIR WARMEST TEMPERATURES OF THE
SEASON.
&&
.AVIATION...CONVECTIVE ACTIVITY HAS PICKED UP THIS AFTERNOON AND
WILL CONTINUE TO BRING HEAVY RAIN...LIGHTNING...AND OCCASIONAL
GUSTY WINDS TO TAF SITES AS LOW PRES PUSHES INLAND. MUCH OF THE
ACTIVITY HAS MAINLY BEEN SOUTH OF SALEM...BUT SHOWERS WILL
CONTINUE TO LIFT NORTH OVERNIGHT. EXPECT MOSTLY MVFR CIGS THROUGH
TONIGHT.
KPDX AND APPROACHES...EXPECT SHOWERS TO INCREASE THROUGH 00Z THIS
AFTERNOON AND CONTINUE INTO FRIDAY MORNING. MVFR CIGS WILL
CONTINUE...WITH VIS DROPPING TO MVFR IN HEAVIER SHOWERS ESPECIALLY
OVERNIGHT. /27
&&
.MARINE...AN UPPER LOW WILL MOVE SOUTH OF THE COASTAL WATERS THIS
AFTERNOON AND MOVE ONSHORE TONIGHT AND EARLY FRIDAY. OVERALL
BENIGN WIND AND SEA CONDITIONS WILL PERSIST THROUGH EARLY
SATURDAY AS THE SYSTEM PUSHES FURTHER INLAND. HIGH PRESSURE OVER
THE NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN
CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME
LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4
TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /27/NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
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...UPDATE
NWS PORTLAND OR
1110 PM PDT WED SEP 4 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL
IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA.
SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO
BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH
WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK.
&&
,MESOSCALE UPDATE...SHOWERS AND TSTORMS HAVE INCREASED IN RESPONSE
TO THE UPPER SHORTWAVE OFF THE COAST IN AN AREA OF UPPER LEVEL
DIVERGENCE/LIFT ON THE LEFT EXIT OF A STRONG HIGH LEVEL JET. EXPECT
THESE TO CONTINUE TO SPREAD NORTH. LATEST HRRR STILL SUGGESTING THIS
MAIN BAND WILL HEAD NORTHWEST TOWARD THE NORTH OREGON COAST
RANGE/COAST...THOUGH ADDITIONAL ACTIVITY IS POSSIBLE FURTHER EAST
TOWARD THE PORTLAND/VANCOUVER METRO AREAS...AS A FEW CELLS HAVE BEEN
POPPING UP OUTSIDE THE MAIN BAND. KMD
.EVENING UPDATE...DOPPLER RADAR THIS EVENING SHOWS LIGHT ECHOES OVER
THE CASCADES AND FOOTHILLS. THESE ECHOES HAVE BEEN PRIMARILY VIRGA
WITH THE ONLY REPORT OF RAIN REACHING THE GROUND COMING FROM VIDA
BRIEFLY THIS EVENING. THIS MID LEVEL CLOUD DECK SHOULD CONTINUE TO
PUSH EAST AND NORTH OF THE REGION AS IT WEAKENS OVERNIGHT.
FOG HAS ALSO DEVELOPED ALONG THE CENTRAL OREGON COAST THIS EVENING SO
FOG WAS ADDED TO THE FORECAST WHERE IT SHOULD LINGER INTO THURSDAY
MORNING.
OUR FOCUS IS QUICKLY TURNING TO THE UPPER LEVEL LOW PRESSURE SPINNING
INSIDE 130W. A VORT MAX LOCATED ON THE SOUTHEAST SIDE OF THE UPPER
LEVEL LOW PRESSURE EARLIER THIS EVENING MOVED NORTHWARD OFF THE
COAST WITH VERY LITTLE IMPACT. HOWEVER...ANOTHER MORE NOTABLE
VORT MAX IS CURRENTLY ROUNDING THE BASE OF THE TROUGH.
UNFORTUNATELY...THIS FEATURE IS EXPECTED TO MOVE INTO SOUTHWESTERN
OREGON OVERNIGHT. NONETHELESS...THIS FEATURE WILL WRAP AROUND THE
APPROACHING LOW PRESSURE CLIPPING OUR SOUTHEASTERN ZONES TOWARDS
THURSDAY MORNING...POSSIBLY AIDING IN CONVECTIVE DEVELOPMENT. IN THE
MEANTIME...THE CWA WILL BE UNDER AN INCREASINGLY DIFFLUENT FLOW
ALOFT WITH NEGATIVE 700-500MB THETAE LAPSE RATES EXPANDING
NORTHWESTWARD ACROSS MUCH OF THE AREA. THE RAP SUGGESTS THE BEST
INSTABILITY WILL BE ALONG AN AXIS EXTENDING BETWEEN EUGENE AND
ASTORIA OVERNIGHT...WITH PERHAPS ANOTHER AXIS EXTENDING INTO THE
SOUTHWEST WASHINGTON CASCADES FROM CENTRAL OREGON. IN FACT...CLOUDS
IN THE PAST HOUR OR SO ARE BEGINNING TO EXPAND IN AREAL
COVERAGE...AND ARE COOLING SLIGHTLY BETWEEN REEDSPORT...EUGENE AND
ROSEBURG...INCREASING CONFIDENCE THE HRRR/RAP IS ONTO SOMETHING. AS
A RESULT...POPS WERE INCREASED IN THESE REGIONS OVERNIGHT WITH
CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE KEPT LOWER
WITH ONLY SLIGHT CHANCE WORDING FOR THUNDERSTORMS DUE TO THE
INHERENT UNCERTAINTY IN THIS TYPE OF PATTERN.
GIVEN PWATS ARE TWO TO THREE STANDARD DEVIATIONS ABOVE
NORMAL...EXPECT RAIN TO BE LOCALLY HEAVY FOR THIS TIME OF YEAR
ESPECIALLY WHERE SHOWERS/THUNDERSTORMS TRAIN. HOWEVER...THE IMPACTS
WILL GENERALLY BE LOCAL IN NATURE AND LIMITED TO URBAN ENVIRONMENTS
AND SMALL STREAMS SO NO FLOOD RELATED PRODUCTS APPEAR NECESSARY AT
THIS POINT IN TIME. /NEUMAN
.LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY...
AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF
DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED
PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS
MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO
SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON
RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE
MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE
REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A
THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE
COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW.
THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A
SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE
UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE
OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR
WARMEST TEMPERATURES OF THE SEASON.
&&
.AVIATION...IFR CONDITIONS ALONG THE CENTRAL OREGON COAST WILL
LIKELY PERSIST FOR MUCH OF THE NIGHT. FURTHER NORTH MVFR DECKS
HAVE BEEN GOING IN AND OUT NEAR KAST. EXPECT THIS TREND TO
CONTINUE OVERNIGHT WITH CONFIDENCE IN ANY PARTICULAR CONDITION
DOMINATING NOT TERRIBLY HIGH. ACROSS THE INTERIOR...CIGS REMAIN
IN THE 3.5 TO 5KFT RANGE...BUT MAY GRADUALLY LOWER THROUGH THE
NIGHT. INSTABILITY ALOFT SHOULD LEAD TO INCREASING SHOWERS AND
POSSIBLY SOME THUNDERSTORMS TONIGHT INTO THURSDAY. THIS INFLUX OF
LOW LEVEL MOISTURE SHOULD AID IN CONDITIONS LOWERING TO MVFR FOR
MOST INTERIOR SITES LATE TONIGHT THROUGH THURSDAY MORNING.
KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING SHOULD GIVE WAY
TO MVFR CIGS LATE TONIGHT INTO THURSDAY MORNING AS SHOWERS
INCREASE. THERE IS A SLIGHT CHANCE A THUNDERSTORM COULD IMPACT
THE TERMINAL AFTER 09Z TONIGHT. /NEUMAN
&&
.MARINE...RATHER BENIGN WIND AND SEA CONDITIONS WILL CONTINUE
THROUGH THE END OF THE WORK WEEK. HIGH PRESSURE OVER THE
NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN
CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME
LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4
TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
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...UPDATE
NWS PORTLAND OR
905 PM PDT WED SEP 4 2013
.SYNOPSIS...AN UPPER LEVEL LOW WILL CONTINUE THE THREAT FOR SHOWERS
AND THUNDERSTORMS TONIGHT THROUGH THURSDAY. LOCALIZED HEAVY RAINFALL
IS EXPECTED THURSDAY AND FRIDAY AS THE LOW MOVES OVER THE AREA.
SHOWERS WILL DECREASE FRIDAY EVENING AS THE HIGH PRESSURE BEGINS TO
BUILD BEHIND THE LOW. DRIER WEATHER IS EXPECTED THIS WEEKEND WITH
WARMING AND CONTINUED DRY WEATHER EXPECTED NEXT WEEK.
&&
.EVENING UPDATE...DOPPLER RADAR THIS EVENING SHOWS LIGHT ECHOES OVER
THE CASCADES AND FOOTHILLS. THESE ECHOES HAVE BEEN PRIMARILY VIRGA
WITH THE ONLY REPORT OF RAIN REACHING THE GROUND COMING FROM VIDA
BRIEFLY THIS EVENING. THIS MID LEVEL CLOUD DECK SHOULD CONTINUE TO
PUSH EAST AND NORTH OF THE REGION AS IT WEAKENS OVERNIGHT.
FOG HAS ALSO DEVELOPED ALONG THE CENTRAL OREGON COAST THIS EVENING SO
FOG WAS ADDED TO THE FORECAST WHERE IT SHOULD LINGER INTO THURSDAY
MORNING.
OUR FOCUS IS QUICKLY TURNING TO THE UPPER LEVEL LOW PRESSURE SPINNING
INSIDE 130W. A VORT MAX LOCATED ON THE SOUTHEAST SIDE OF THE UPPER
LEVEL LOW PRESSURE EARLIER THIS EVENING MOVED NORTHWARD OFF THE
COAST WITH VERY LITTLE IMPACT. HOWEVER...ANOTHER MORE NOTABLE
VORT MAX IS CURRENTLY ROUNDING THE BASE OF THE TROUGH.
UNFORTUNATELY...THIS FEATURE IS EXPECTED TO MOVE INTO SOUTHWESTERN
OREGON OVERNIGHT. NONETHELESS...THIS FEATURE WILL WRAP AROUND THE
APPROACHING LOW PRESSURE CLIPPING OUR SOUTHEASTERN ZONES TOWARDS
THURSDAY MORNING...POSSIBLY AIDING IN CONVECTIVE DEVELOPMENT. IN THE
MEANTIME...THE CWA WILL BE UNDER AN INCREASINGLY DIFFLUENT FLOW
ALOFT WITH NEGATIVE 700-500MB THETAE LAPSE RATES EXPANDING
NORTHWESTWARD ACROSS MUCH OF THE AREA. THE RAP SUGGESTS THE BEST
INSTABILITY WILL BE ALONG AN AXIS EXTENDING BETWEEN EUGENE AND
ASTORIA OVERNIGHT...WITH PERHAPS ANOTHER AXIS EXTENDING INTO THE
SOUTHWEST WASHINGTON CASCADES FROM CENTRAL OREGON. IN FACT...CLOUDS
IN THE PAST HOUR OR SO ARE BEGINNING TO EXPAND IN AREAL
COVERAGE...AND ARE COOLING SLIGHTLY BETWEEN REEDSPORT...EUGENE AND
ROSEBURG...INCREASING CONFIDENCE THE HRRR/RAP IS ONTO SOMETHING. AS
A RESULT...POPS WERE INCREASED IN THESE REGIONS OVERNIGHT WITH
CHANCE WORDING OF THUNDERSTORMS. ELSEWHERE...POPS WERE KEPT LOWER
WITH ONLY SLIGHT CHANCE WORDING FOR THUNDERSTORMS DUE TO THE
INHERENT UNCERTAINTY IN THIS TYPE OF PATTERN.
GIVEN PWATS ARE TWO TO THREE STANDARD DEVIATIONS ABOVE
NORMAL...EXPECT RAIN TO BE LOCALLY HEAVY FOR THIS TIME OF YEAR
ESPECIALLY WHERE SHOWERS/THUNDERSTORMS TRAIN. HOWEVER...THE IMPACTS
WILL GENERALLY BE LOCAL IN NATURE AND LIMITED TO URBAN ENVIRONMENTS
AND SMALL STREAMS SO NO FLOOD RELATED PRODUCTS APPEAR NECESSARY AT
THIS POINT IN TIME. /NEUMAN
.LONG TERM...SATURDAY EVENING THROUGH WEDNESDAY...
AFTER THE FALL LIKE WEATHER EXPECTED OVER THE NEXT COUPLE OF
DAYS...IT APPEARS THAT SUMMER WILL MAKE ITS RETURN IN THE EXTENDED
PERIOD. THE CLOSED LOW THAT IS IMPACTING THE REGION THIS WEEK IS
MODELED TO BE EJECTED INTO THE ROCKIES DURING THE SAT NIGHT INTO
SUNDAY TIMEFRAME. THIS WILL OPEN THE DOOR FOR A STRONG LATE SEASON
RIDGE TO BUILD INTO THE PAC NW NEXT WEEK. THE LATEST MEDIUM RANGE
MODELS INDICATE THAT 500 MB HEIGHTS WILL NEAR 590 DM OVER THE
REGION...WITH 850 MB TEMPS NEAR 20C BY TUE OR WED. MEANWHILE A
THERMAL INDUCED SURFACE TROUGH IS PROGGED TO BUILD ALONG THE
COAST...BRINGING AN EASTERLY COMPONENT TO THE LOW LEVEL FLOW.
THUS...IT IS LOOKING MORE AND MORE LIKELY THAT WE WILL SEE A
SIGNIFICANT WARM UP NEXT WEEK. HIGH TEMPS WERE BUMPED UP INTO THE
UPPER 80S FOR THE INTERIOR LOWLANDS FOR BOTH TUE AND WED. THE
OFFSHORE FLOW PATTERN WOULD ALSO ALLOW THE COAST TO SEE SOME OF THEIR
WARMEST TEMPERATURES OF THE SEASON.
&&
.AVIATION...IFR CONDITIONS ALONG THE CENTRAL OREGON COAST WILL
LIKELY PERSIST FOR MUCH OF THE NIGHT. FURTHER NORTH MVFR DECKS
HAVE BEEN GOING IN AND OUT NEAR KAST. EXPECT THIS TREND TO
CONTINUE OVERNIGHT WITH CONFIDENCE IN ANY PARTICULAR CONDITION
DOMINATING NOT TERRIBLY HIGH. ACROSS THE INTERIOR...CIGS REMAIN
IN THE 3.5 TO 5KFT RANGE...BUT MAY GRADUALLY LOWER THROUGH THE
NIGHT. INSTABILITY ALOFT SHOULD LEAD TO INCREASING SHOWERS AND
POSSIBLY SOME THUNDERSTORMS TONIGHT INTO THURSDAY. THIS INFLUX OF
LOW LEVEL MOISTURE SHOULD AID IN CONDITIONS LOWERING TO MVFR FOR
MOST INTERIOR SITES LATE TONIGHT THROUGH THURSDAY MORNING.
KPDX AND APPROACHES...VFR CONDITIONS THIS EVENING SHOULD GIVE WAY
TO MVFR CIGS LATE TONIGHT INTO THURSDAY MORNING AS SHOWERS
INCREASE. THERE IS A SLIGHT CHANCE A THUNDERSTORM COULD IMPACT
THE TERMINAL AFTER 09Z TONIGHT. /NEUMAN
&&
.MARINE...RATHER BENIGN WIND AND SEA CONDITIONS WILL CONTINUE
THROUGH THE END OF THE WORK WEEK. HIGH PRESSURE OVER THE
NORTHEAST PACIFIC OCEAN AND THERMAL LOW PRESSURE OVER NORTHERN
CALIFORNIA WILL STRENGTHEN OVER THE WEEKEND...RESULTING IN SOME
LATE AFTERNOON AND EVENING GUSTY 25 KT WINDS WITH SEAS RUNNING 4
TO 6 FT. SEAS LOOK TO REMAIN UNDER 10 FT NEXT WEEK. /NEUMAN
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WA...NONE.
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
1134 PM EDT FRI SEP 6 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY.
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY...
FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK.
TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING
HUMIDITY INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO
PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E
GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE
WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF
OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS
RUNNING IN THE M40S ACROSS MOST OF THE REGION.
THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH
PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST
TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS
OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS
TOWARD DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR
MOST OF THE REGION...SO ANY FOG SHOULD BE ISOLATED.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN
STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER
SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY
TO MOSTLY SUNNY SKIES.
A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF
A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN
PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE
FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL
BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS.
HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE
NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR
80F THROUGHOUT THE LOWER SUSQ VALLEY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN
ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS
THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE
PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/
DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST
ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO
THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE
ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT.
DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR
SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED
SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING
THE MORNING.
ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR
SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER
GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL
TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP
BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY
INT HE 40S ELSEWHERE.
MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND
AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST.
A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN
DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE
US. TEMPS WILL AGAIN MOVE ABOVE NORMAL.
THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM
OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT
AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY
EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE
CFRONT.
DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE
UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND
STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER
AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY
ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS
OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY
SKIES SHOULD PREVAIL ELSEWHERE.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
NO CHANGES MADE TO 03Z TAFS.
EARLIER DISCUSSION BELOW.
OTHER THAN A FEW HIGH AND MID CLDS...GREAT LATE
SUMMER WEATHER WILL PREVAIL INTO SAT...AS HIGH PRESSURE
SLOWLY MOVES OFF THE COAST. EXPECT VFR CONDITIONS TO
PREVAIL INTO SAT.
ANOTHER STRONG COLD FRONT WILL DROP SOUTH ACROSS THE
REGION SUNDAY MORNING. LIKE THE LAST FRONT...LIMITED
MOISTURE...BUT WITH DECENT DYNAMICS...THERE COULD BE
A SHOWER...MAINLY ACROSS NORTHERN PA. AS WAS THE CASE
ON THU MORNING...CIGS COULD BRIEFLY GO MVFR WITH THE
COLD FRONT AND UPSLOPE FLOW.
A RETURN TO DRY CONDITIONS FOR MONDAY.
VERY WARM AIR FROM THE PLAINS WILL WORK EASTWARD INTO
THE AREA FOR TUE AND WED. THERE COULD BE A SHOWER OR
THUNDERSTORM WITH THE WARM FRONT. MOST OF THE TIME
SHOULD BE DRY WITH VFR CONDITIONS.
OUTLOOK...
SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA.
MON...VFR. NO SIG WX.
TUE/WED...AM FOG PSBL. VFR WITH ISOLD TSTM IMPACTS PSBL.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1034 PM EDT FRI SEP 6 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY.
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY...
FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK.
TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING
HUMIDITY INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO
PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E
GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE
WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF
OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS
RUNNING IN THE M40S ACROSS MOST OF THE REGION.
THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH
PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST
TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS
OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS TOWARD
DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR MOST OF
THE REGION...SO ANY FOG SHOULD BE ISOLATED.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN
STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER
SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY
TO MOSTLY SUNNY SKIES.
A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF
A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN
PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE
FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL
BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS.
HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE
NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR
80F THROUGHOUT THE LOWER SUSQ VALLEY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN
ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS
THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE
PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/
DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST
ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO
THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE
ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT.
DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR
SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED
SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING
THE MORNING.
ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR
SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER
GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL
TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP
BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY
INT HE 40S ELSEWHERE.
MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND
AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST.
A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN
DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE
US. TEMPS WILL AGAIN MOVE ABOVE NORMAL.
THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM
OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT
AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY
EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE
CFRONT.
DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE
UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND
STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER
AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY
ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS
OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY
SKIES SHOULD PREVAIL ELSEWHERE.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
OTHER THAN A FEW HIGH AND MID CLDS...GREAT LATE
SUMMER WEATHER WILL PREVAIL INTO SAT...AS HIGH PRESSURE
SLOWLY MOVES OFF THE COAST. EXPECT VFR CONDITIONS TO
PREVAIL INTO SAT.
ANOTHER STRONG COLD FRONT WILL DROP SOUTH ACROSS THE
REGION SUNDAY MORNING. LIKE THE LAST FRONT...LIMITED
MOISTURE...BUT WITH DECENT DYNAMICS...THERE COULD BE
A SHOWER...MAINLY ACROSS NORTHERN PA. AS WAS THE CASE
ON THU MORNING...CIGS COULD BRIEFLY GO MVFR WITH THE
COLD FRONT AND UPSLOPE FLOW.
A RETURN TO DRY CONDITIONS FOR MONDAY.
VERY WARM AIR FROM THE PLAINS WILL WORK EASTWARD INTO
THE AREA FOR TUE AND WED. THERE COULD BE A SHOWER OR
THUNDERSTORM WITH THE WARM FRONT. MOST OF THE TIME
SHOULD BE DRY WITH VFR CONDITIONS.
OUTLOOK...
SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA.
MON...VFR. NO SIG WX.
TUE/WED...AM FOG PSBL. VFR WITH ISOLD TSTM IMPACTS PSBL.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
931 PM EDT FRI SEP 6 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY.
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY...
FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK.
TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING
HUMIDITY INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE TOWARD PA IN
AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT
LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL
BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF
THE STATE. HAVE THEREFORE RAISED OVERNIGHT MIN TEMPS A BIT ACROSS
THE NW MTNS.
THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH
PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST
TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS
OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE TOWARD DAWN IN THE DEEP
RIVER/STREAM VALLEYS OF THE ALLEGHENIES. HOWEVER...TEMPS WILL BE MILDER
THAN LAST NIGHT OVR MOST OF THE REGION...WITH LOWS IN THE M40S MOST
SPOTS...SO ANY FOG SHOULD BE ISOLATED.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN
STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER
SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY
TO MOSTLY SUNNY SKIES.
A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF
A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN
PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE
FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL
BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS.
HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE
NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR
80F THROUGHOUT THE LOWER SUSQ VALLEY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN
ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS
THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE
PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/
DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST
ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO
THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE
ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT.
DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR
SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED
SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING
THE MORNING.
ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR
SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER
GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL
TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP
BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY
INT HE 40S ELSEWHERE.
MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND
AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST.
A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN
DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE
US. TEMPS WILL AGAIN MOVE ABOVE NORMAL.
THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM
OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT
AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY
EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE
CFRONT.
DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE
UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND
STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER
AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY
ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS
OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY
SKIES SHOULD PREVAIL ELSEWHERE.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
OTHER THAN A FEW HIGH AND MID CLDS...GREAT LATE
SUMMER WEATHER WILL PREVAIL INTO SAT...AS HIGH PRESSURE
SLOWLY MOVES OFF THE COAST. EXPECT VFR CONDITIONS TO
PREVAIL INTO SAT.
ANOTHER STRONG COLD FRONT WILL DROP SOUTH ACROSS THE
REGION SUNDAY MORNING. LIKE THE LAST FRONT...LIMITED
MOISTURE...BUT WITH DECENT DYNAMICS...THERE COULD BE
A SHOWER...MAINLY ACROSS NORTHERN PA. AS WAS THE CASE
ON THU MORNING...CIGS COULD BRIEFLY GO MVFR WITH THE
COLD FRONT AND UPSLOPE FLOW.
A RETURN TO DRY CONDITIONS FOR MONDAY.
VERY WARM AIR FROM THE PLAINS WILL WORK EASTWARD INTO
THE AREA FOR TUE AND WED. THERE COULD BE A SHOWER OR
THUNDERSTORM WITH THE WARM FRONT. MOST OF THE TIME
SHOULD BE DRY WITH VFR CONDITIONS.
OUTLOOK...
SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA.
MON...VFR. NO SIG WX.
TUE/WED...AM FOG PSBL. VFR WITH ISOLD TSTM IMPACTS PSBL.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
816 PM EDT FRI SEP 6 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY.
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY...
FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK.
TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING
HUMIDITY INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE TOWARD PA IN
AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E GRT
LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE WILL
BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF OF
THE STATE. HAVE THEREFORE RAISED OVERNIGHT MIN TEMPS A BIT ACROSS
THE NW MTNS.
THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH
PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST
TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS
OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE TOWARD DAWN IN THE DEEP
RIVER/STREAM VALLEYS OF THE ALLEGHENIES. HOWEVER...TEMPS WILL BE MILDER
THAN LAST NIGHT OVR MOST OF THE REGION...WITH LOWS IN THE M40S MOST
SPOTS...SO ANY FOG SHOULD BE ISOLATED.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN
STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER
SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY
TO MOSTLY SUNNY SKIES.
A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF
A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN
PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE
FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL
BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS.
HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE
NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR
80F THROUGHOUT THE LOWER SUSQ VALLEY.
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN
ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS
THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE
PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/
DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST
ACROSS THE SE. LOWS WILL BE NOTICABLY MILDER...ONLY DROPPING INTO
THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE
ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT.
DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR
SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED
SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING
THE MORNING.
ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR
SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER
GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL
TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP
BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY
INT HE 40S ELSEWHERE.
MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND
AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST.
A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN
DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE
US. TEMPS WILL AGAIN MOVE ABOVE NORMAL.
THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM
OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT
AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY
EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE
CFRONT.
DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE
UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND
STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER
AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY
ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS
OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY
SKIES SHOULD PREVAIL ELSEWHERE.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
CLEAR SKIES AND LIGHT WINDS WILL PREVAIL OVERNIGHT.
EARLIER DISCUSSION BELOW.
VFR FLYING WILL BE THE RULE THROUGH SATURDAY WITH CLR SKIES AND
LGT WINDS...AS SFC HIGH PRESSURE DRIFTS SEWD FROM WRN PA TO THE
NC/VA COAST. SOME FOG IS POSSIBLE AROUND DAYBREAK ESPECIALLY NEAR
BODIES OF WATER...RIVER-STREAM VALLEYS...BUT THE DRY CANADIAN
AIRMASS SHOULD LIMIT VSBY RESTRICTIONS.
A COLD FRONT WILL PUSH SWD FROM THE LWR GRT LKS THRU THE AIRSPACE
ON SUNDAY. THE FRONT SHOULD BE PRECEDED BY SCT LGT SHOWERS...FOLLOWED
BY A WSW-NNW SFC WIND SHIFT AND A BAND OF LOWER END VFR TO MVFR
CIGS. HIGH PRES RETURNS ON MONDAY WITH VFR PREVAILING INTO TUES.
SOME AM FOG IS POSSIBLE TUESDAY MORNING AS LLVL MSTR GRADUALLY
INCREASES WIND SFC WINDS BCMG S-SW. THE INCREASE IN MSTR/HUMIDITY
MAY SUPPORT ISOLD CONVECTION TUES AFTN-EVE OVR WRN PA/ZOB SECTOR.
OUTLOOK...
SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA.
MON...VFR. NO SIG WX.
TUE/WED...AM FOG PSBL. VFR WITH ISOLD PM TSTM IMPACTS PSBL WEST.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...DEVOIR/LA CORTE/MARTIN
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1226 PM CDT THU SEP 5 2013
.DISCUSSION...
See aviation discussion below...
&&
.AVIATION...
Isolated showers will develop across the southern half of West
Central Texas this afternoon. I have included a VCTS mention at
KJCT, KSOA, and KBBD, ending shortly after sunrise. For now I have
left a mention of thunder out of the KABI and KSJT TAF, but I will
continue to monitor. Otherwise, expect light winds and VFR
conditions through the next 24 hours.
&&
.PREV DISCUSSION... /ISSUED 1144 AM CDT THU SEP 5 2013/
UPDATE...
To expand POPS north...
DISCUSSION...
I sent out a quick update to expand isolated POPS north into the
Heartland and Concho Valley this afternoon. A cumulus field is
beginning to develop across the region, with low level moisture
higher than originally anticipated. High resolution models including
the Texas Tech WRF and HRRR are indicating isolated showers and
thunderstorms developing this afternoon across the southern half of
West Central Texas. For this reason, I have expanded POPS north as
previously mentioned. I have also tweaked temperatures down a degree
or two across much of the region, given the expected higher
dewpoints and increased cloud cover...with the hottest temperatures
across the Big Country. Otherwise, no other changes are needed at
this time.
PREV DISCUSSION... /ISSUED 630 AM CDT THU SEP 5 2013/
DISCUSSION...
Please see aviation section below for discussion.
AVIATION...
Look for beautiful flight weather to continue across West Central
Texas for the next 24 hours. High pressure will continue to
dominate; thus, I`m expecting light surface winds around 6 knots or
less for another 24 hours.
Huber
PREV DISCUSSION... /ISSUED 427 AM CDT THU SEP 5 2013/
SHORT TERM...
(today and tonight)
Thunderstorms may develop across our Northern Edwards Plateau and
Northwest Hill Country counties this afternoon and evening.
Otherwise, expect hot and dry conditions to continue for at least
another 24 hours. High pressure will remain dominate over the
southern Plains for the next 24 hours. Our southern counties will
remain just outside the major influence of this high and its
associated subsidence. Thus, I`ve decided to continue slight chance
POPs across our southern counties, as this area has been an area of
convective development during the last couple afternoons. As for
temperatures, I`m going with highs today just above the adjusted MEX
model data, simply because that`s been the trend the last couple
days, with highs just above model guidance. Lows tonight close to
persistence look reasonable.
Huber
LONG TERM...
(Friday through Wednesday)
The main forecast items of interest in the long term include
possible low rain chances in the southern part of our forecast
area, and a slow decrease in maximum temperatures over the course
of several days.
Friday through the weekend, the upper high will slowly weaken as it
shifts east across Kansas. Our area will continue to be on the
southern periphery of this upper high. The 00Z GFS and NAM are less
favorable with QPF across our southern counties on Friday. However,
given what has occurred during the past couple of days, plan to
continue with low POPs in our southern counties for isolated
afternoon and evening showers/thunderstorms across that area, where
sufficient moisture should remain.
On the fence whether to carry an isolated mention for afternoon/
early evening showers and thunderstorms this weekend across roughly
the southern third of West Central Texas. The 00Z models have
trended down a bit with mid-level moisture, and mid/upper forcing
will be weak. Planning to leave out the mention for now.
Early next week the upper level high is progged to shift into the
southeastern part of the country, with an upper trough moving east
across the northern Plains and into southwestern Ontario Province
in Canada. Over our area, the flow aloft will transition to
southeasterly through a deeper layer, but with the latest model
indications this may be short-lived. The 00Z GFS and ECMWF show
more ridging aloft over the northern half of Texas by the middle of
next week. With uncertainty in the specifics of how the upper level
pattern will evolve next week, holding off with any mentionable
rain chance in our counties at this time.
With a slight decrease in 850 mb temperatures across our area along
with some increase in cloud cover, maximum temperatures are expected
to decrease by a few degrees, over a period of several days.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 73 96 71 96 71 / 5 5 10 5 5
San Angelo 72 96 69 94 71 / 10 10 10 10 5
Junction 72 95 70 94 71 / 20 10 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Daniels
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1144 AM CDT THU SEP 5 2013
.UPDATE...
To expand POPS north...
&&
.DISCUSSION...
I sent out a quick update to expand isolated POPS north into the
Heartland and Concho Valley this afternoon. A cumulus field is
beginning to develop across the region, with low level moisture
higher than originally anticipated. High resolution models including
the Texas Tech WRF and HRRR are indicating isolated showers and
thunderstorms developing this afternoon across the southern half of
West Central Texas. For this reason, I have expanded POPS north as
previously mentioned. I have also tweaked temperatures down a degree
or two across much of the region, given the expected higher
dewpoints and increased cloud cover...with the hottest temperatures
across the Big Country. Otherwise, no other changes are needed at
this time.
&&
.PREV DISCUSSION... /ISSUED 630 AM CDT THU SEP 5 2013/
DISCUSSION...
Please see aviation section below for discussion.
AVIATION...
Look for beautiful flight weather to continue across West Central
Texas for the next 24 hours. High pressure will continue to
dominate; thus, I`m expecting light surface winds around 6 knots or
less for another 24 hours.
Huber
PREV DISCUSSION... /ISSUED 427 AM CDT THU SEP 5 2013/
SHORT TERM...
(today and tonight)
Thunderstorms may develop across our Northern Edwards Plateau and
Northwest Hill Country counties this afternoon and evening.
Otherwise, expect hot and dry conditions to continue for at least
another 24 hours. High pressure will remain dominate over the
southern Plains for the next 24 hours. Our southern counties will
remain just outside the major influence of this high and its
associated subsidence. Thus, I`ve decided to continue slight chance
POPs across our southern counties, as this area has been an area of
convective development during the last couple afternoons. As for
temperatures, I`m going with highs today just above the adjusted MEX
model data, simply because that`s been the trend the last couple
days, with highs just above model guidance. Lows tonight close to
persistence look reasonable.
Huber
LONG TERM...
(Friday through Wednesday)
The main forecast items of interest in the long term include
possible low rain chances in the southern part of our forecast
area, and a slow decrease in maximum temperatures over the course
of several days.
Friday through the weekend, the upper high will slowly weaken as it
shifts east across Kansas. Our area will continue to be on the
southern periphery of this upper high. The 00Z GFS and NAM are less
favorable with QPF across our southern counties on Friday. However,
given what has occurred during the past couple of days, plan to
continue with low POPs in our southern counties for isolated
afternoon and evening showers/thunderstorms across that area, where
sufficient moisture should remain.
On the fence whether to carry an isolated mention for afternoon/
early evening showers and thunderstorms this weekend across roughly
the southern third of West Central Texas. The 00Z models have
trended down a bit with mid-level moisture, and mid/upper forcing
will be weak. Planning to leave out the mention for now.
Early next week the upper level high is progged to shift into the
southeastern part of the country, with an upper trough moving east
across the northern Plains and into southwestern Ontario Province
in Canada. Over our area, the flow aloft will transition to
southeasterly through a deeper layer, but with the latest model
indications this may be short-lived. The 00Z GFS and ECMWF show
more ridging aloft over the northern half of Texas by the middle of
next week. With uncertainty in the specifics of how the upper level
pattern will evolve next week, holding off with any mentionable
rain chance in our counties at this time.
With a slight decrease in 850 mb temperatures across our area along
with some increase in cloud cover, maximum temperatures are expected
to decrease by a few degrees, over a period of several days.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 98 73 96 71 96 / 10 5 5 10 5
San Angelo 98 72 96 69 94 / 10 10 10 10 10
Junction 95 72 95 70 94 / 20 20 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Daniels
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
610 AM CDT THU SEP 5 2013
.DISCUSSION...
SEE 12Z AVIATION DISCUSSION.
&&
.AVIATION...
MODELS DID NOT INITIALIZE WELL OVERNIGHT. NAM AND GFS SHOW THE
BEST OMEGA FIELDS OVER THE NORTHERN TAF SITES WHILE THE HRRR AND 4
KM WRF FAVOR SHRA/TSRA ALONG COAST. AT 09Z...A WEAK TROUGH
EXTENDED FROM THE LOUISIANA COASTAL WATERS...NORTHWEST TOWARD
KCLL. FCST SOUNDINGS SHOW PW VALUES PEAKING NEAR 2.00 INCHES
BETWEEN 21-00Z. THE UPPER RIDGE OVER THE SOUTHERN PLAINS SHOULD
IMPART SOME SUBSIDENCE TODAY BUT STILL FEEL HEATING COUPLED WITH
2.0 PW AIR WILL YIELD AFTN SHRA/TSRA. GENERALLY CLEAR SKIES AND
LIGHT WINDS OVERNIGHT. COLD BE SHRA NEAR KGLS EARLY FRIDAY MORNING
AND MORE OF AN EAST WIND ON FRIDAY. 43
&&
.PREV DISCUSSION... /ISSUED 435 AM CDT THU SEP 5 2013/
DISCUSSION...
ANOTHER WARM AND MUGGY NIGHT ACROSS SOUTHEAST TEXAS THIS MORNING
WITH TEMPERATURES IN THE MID 70S IN MOST LOCATIONS. THERE IS A
POSSIBILITY OF SOME PATCHY FOG IN RURAL AREAS THIS MORNING
(ESPECIALLY AREAS THAT HAVE SEEN RAIN) AS NEARLY CALM WINDS HAS
ALLOWED DEWPOINT DEPRESSIONS TO DROP TO AROUND A DEGREE OR TWO IN
SOME LOCATIONS. THERE ALSO HAS BEEN SOME RAIN IN THE GULF THIS
MORNING AS A WEDGE OF VORTICITY MOVES ACROSS THE AREA.
MODELS AGAIN APPEAR TO BE HAVING DIFFICULTY WITH HANDLING MOISTURE
VALUES ACROSS THE AREA. ACCORDING TO GPS MET KCLL PWAT VALUES HAVE
HELD STEAD AROUND 1.8 - 1.9" THE LAST TWO DAYS WHILE BOTH NAM AND
GFS FORECAST SOUNDINGS HAVE SHOWN PWAT VALUES DROPPING TO AROUND
1.6". AGAIN TODAY GFS AND NAM FORECAST SOUNDINGS SHOW PWAT VALUES
AROUND 1.6" AND 1.5" RESPECTIVELY. BOTH FORECAST SOUNDINGS ALSO
SHOW DRY AIR IN THE MID-LEVELS. THE KLCH 0Z SOUNDING SHOWS A PWAT
OF 2.12" WHILE KFWD 0Z SOUNDINGS SHOWS A PWAT OF ONLY 1.10". GIVEN
THE GPS MET DERIVED PWAT FEEL THAT OUR AREA IS MORE REPRESENTED BY
THE KLCH SOUNDING. GFS AND NAM OMEGA FIELDS ARE HINTING AT LIFT
NORTH OF I-10 TODAY AND GIVEN THE MOISTURE VALUES IN PLACE
SCATTERED SHOWERS AND THUNDERSTORMS AGAIN LOOK POSSIBLE. BEST
UPPER LEVEL DIFFLUENCE STILL APPEARS TO BE OFF TO THE EAST TODAY
THOUGH.
THE UPPER LEVEL RIDGE CURRENTLY OVER COLORADO WILL CONTINUE TO
MOVE EASTWARDS THIS WEEKEND. THE TROPICAL WAVE CURRENTLY LOCATED
OVER THE YUCATAN WILL DRIFT EASTWARD FRIDAY INTO SATURDAY. WITH
THE RIDGE TO THE NORTH THE BEST CHANCES OF RAIN APPEAR TO BE IN
THE SOUTHERN ZONES AND OFFSHORE WATERS. THE NEXT TROPICAL WAVE
WILL APPROACH THE AREA LATE TUESDAY INTO EARLY WEDNESDAY. THE GFS
WEAKENS THE UPPER LEVEL RIDGE ALLOWING THE WAVE TO DRIFT FARTHER
NORTHWARDS WILL THE ECMWF SHOWS A SLIGHTLY STRONGER RIDGE WHICH
KEEPS THE WAVE FURTHER SOUTH. A SLIGHT DEVIATION IN THE TRACK OF
THE UPPER LEVEL RIDGE COULD DRASTICALLY CHANGE TO AMOUNT OF RAIN
SEEN ACROSS THE REGION. MODELS HAVE ALSO SHOWN LITTLE CONSISTENCY
ON THIS FEATURE THE LAST COUPLE OF DAYS. MADE ONLY MINOR CHANGES
TO POPS GIVEN LACK OF CONSISTENCY IN MODELS. 23
MARINE...
A RELATIVELY WEAK PRESSURE GRADIENT WILL REMAIN IN PLACE WITH LIGHT
ONSHORE WINDS EXPECTED. A SERIES OF WEAK EASTERLY WAVES WILL MOVE
INTO MEXICO WITH THE FIRST WAVE MOVING TOWARD THE MEXICAN COAST ON
TONIGHT INTO FRIDAY AND A SECOND STRONGER WAVE MOVING INLAND ON
SUNDAY. THIS SHOULD SUPPORT EASTERLY WINDS AND SEAS AROUND 3 FEET.
SLIGHTLY HIGHER SEAS WILL BE POSSIBLE SUN-MON DUE TO PERSISTENT EAST
TO SOUTHEAST WINDS. THE PERSISTENT E-SE WINDS WILL ALSO PRODUCE A SUBTLE
INCREASE IN TIDE LEVELS. 43
&&
.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL) 98 75 98 75 97 / 30 10 20 10 20
HOUSTON (IAH) 97 76 97 75 96 / 30 20 20 20 20
GALVESTON (GLS) 90 80 89 80 89 / 30 20 30 20 30
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
DISCUSSION...23
AVIATION/MARINE...43
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1135 PM CDT WED SEP 4 2013
.DISCUSSION...
/See below for aviation discussion/
&&
.AVIATION...
VFR next 24 hours. Isolated afternoon and evening thunderstorms are
possible Thursday afternoon and evening at KSOA, KJCT, and KBBD.
Coverage however is expected to be too low for mention in TAFS.
Light winds tonight become southeast to south at 10 mph or less
Thursday.
04
&&
.PREV DISCUSSION... /ISSUED 936 PM CDT WED SEP 4 2013/
.UPDATE...
Most of the convective activity that developed this afternoon across
West Central TX has dissipated. However, we are seeing storms over
the I-35 corridor from Waco to near San Antonio holding together,
continuing a general westerly trend. While most of this activity
will continue to weak, the HRRR is suggesting additional shower
development tonight across mainly the Heartland Counties overnight
(namely Brown, Coleman, San Saba, and McCulloch Counties). I trimmed
PoPs back across the southwest counties for the remainder of the
overnight period and extended the mention of isolated thunderstorms
through 08z to account for this possibility.
Dewpoints across the Big Country tanked into the mid 30s this
afternoon due to strong subsidence and associated dry air mixing to
the surface. This brought precipitable water values below 1 inch
across the northwest half of the forecast area with pwats near 1.4
inches across the southeast. The bulk of the deeper moisture will
remain to our south and east through tomorrow but we will see
similar pwat values again tomorrow, suggesting the potential for
additional diurnal convection, especially across the southern half
of the area. For tonight, dewpoints will be slow to recover and
should allow temperatures to fall into the upper 60s, especially in
areas where cloud cover will be sparse. Min temps were updated
accordingly.
Johnson
&&
.PREV DISCUSSION... /ISSUED 552 PM CDT WED SEP 3 2013/
DISCUSSION...
/See below for aviation discussion/
AVIATION...
VFR next 24 hours. Isolated thunderstorms possible Thursday afternoon
south of the I-20 corridor. However potential is too low to include
in TAFS.
04
PREV DISCUSSION... /ISSUED 352 PM CDT WED SEP 3 2013/
SHORT TERM...(Tonight and Thursday)
Isolated showers and a few storms possible this afternoon and early
this evening, and again on Thursday afternoon and evening.
West Central Texas remains on the edge of the large upper level high
pressure dominating much of the southern plains. Abundant moisture
with east winds prevailing at most levels will combine with
afternoon temperatures climbing into the mid 90s to produce a few
storms. These storms will mainly be along the edge of the ridge axis
itself, across the southern and eastern portions of the area. Have
inserted a mention of storms into the forecast itself through the
early evening hours tonight and again for a few hours Thursday
afternoon.
Otherwise, clouds having an impact on temperatures this afternoon
and expect of the same tomorrow. Readings in the mid and upper 90s
across the northern half of the area, while the southern half of the
area runs in the lower 90s.
LONG TERM...(Thursday Night through Wednesday)
The upper ridge will remain centered over the Southern Plains
through this weekend with above normal temperatures continuing.
Cannot rule out isolated convection developing again across far
southern counties Friday afternoon/early evening so will include
this potential this forecast cycle.
By early next week, a short wave trough will move east across
the Northern Plains and across the Great Lakes region by mid week.
This system will push the upper high east of the area for the latter
part of the extended period and allow afternoon highs to cool a few
degrees. The upper high will be situated over the Ohio and Tennessee
Valleys, which will result in deeper low to mid level southeasterly
flow across the area. This pattern would be more favorable for
diurnal convection, especially across southeast sections Monday
through Wednesday of next week. Kept the forecast dry for now given
uncertainties this far out and wait to see how models perform in
subsequent runs before considering adding POPS to the
forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 68 96 71 96 71 / 0 5 5 5 5
San Angelo 69 95 69 96 70 / 5 10 10 10 10
Junction 68 95 69 95 70 / 10 10 10 10 10
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
25
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1002 PM CDT FRI SEP 6 2013
.UPDATE...
NO CHANGES TO GOING FORECAST. LATEST NAM HOLDS ANY PCPN IN THE CWA
TO THE FAR NORTHWEST CLOSE TO THE APPROACHING FRONT/TROUGH...
MAINLY AROUND/AFTER 09Z. 00Z HRRR EVEN MORE MEAGER WITH PCPN
THROUGH 10Z THAN EARLIER RUNS...AND SIMILAR TO LATEST NAM WITH THE
NW CWA SEEING ONLY A SLIGHT CHANCE BEFORE 12Z.
&&
.AVIATION/06Z TAFS/...
KEEPING VFR CONDITIONS AND NO PCPN AT ANY TAF SITES UNTIL AFTER
12Z. LATEST MODELS STILL INDICATING GROWING INSTABILITY DURING THE
DAY TO PRODUCE POTENTIAL OF SCATTERED SHOWERS/THUNDERSTORMS
SATURDAY AFTERNOON. CONFIDENCE IS STILL LIMITED SO WILL STAY WITH
VICINITY THUNDER FOR NOW AND AWAIT REST OF THE MODEL GUIDANCE.
&&
.MARINE...
LATEST NAM RUN COMING IN WITH SUSTAINED 15 KNOT NORTHEAST WINDS
BEHIND COLD FRONT...BEGINNING AROUND/AFTER MIDNIGHT SATURDAY NIGHT
AND CONTINUING THROUGH THE DAY SUNDAY...WITH BUFKIT SOUNDINGS
INDICATING MIXING UP TO 23 TO 26 KNOT WINDS JUST OFF THE SURFACE
INTO THE LATE MORNING...THEN SLOWLY EASING AND BECONING MORE
EASTERLY DURING THE AFTERNOON. GOOD POTENTIAL FOR SMALL CRAFT
CONDITIONS FROM OVERNIGHT SATURDAY NIGHT THROUGH SUNDAY
AFTERNOON...INITIALLY FOR WINDS THAT BUILD HIGH WAVES...THEN FOR
WAVES THAT WILL BE SLOWER TO SUBSIDE AFTER THE WINDS EASE.
&&
.PREV DISCUSSION... /ISSUED 330 PM CDT FRI SEP 6 2013/
TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS MEDIUM.
A WEAK SHORTWAVE/VORT MAX RIDING OVER AN UPPER LEVEL RIDGE
CENTERED OVER THE GREAT PLAINS WILL CROSS CENTRAL WI
OVERNIGHT...ALONG THE 850-700MB THERMAL RIDGE...AND CLEAR
SOUTHEAST WI AROUND 15Z SATURDAY. THE MAIN MOISTURE TRANSPORT
OVERNIGHT WILL BE NORTH OF THE MKX FORECAST AREA /CWA/...SO KEPT
THUNDER MENTION OUT UNTIL EARLY SATURDAY MORNING. AFTER 09Z...THE
DEEPER MOISTURE WILL MAKE IT INTO MAINLY THE EASTERN
CWA...COINCIDENT WITH THE MID LEVEL SHORTWAVE. MODEL SOUNDINGS
SHOW INCREASING MID LEVEL LAPSE RATES WITH THIS FEATURE SO
ELEVATED THUNDERSTORMS WILL BE POSSIBLE EARLY SATURDAY MORNING
THROUGH NOONISH.
PRECIP COVERAGE ALONG THE COLD FRONT SATURDAY AFTERNOON AND
EVENING IS UNCERTAIN. MANY OF THE HI-RES MODELS SHOW SCATTERED
CONVECTION NEAR THE FRONT AT BEST. SPC HAS SOUTHERN WI IN A SEE
TEXT AREA GIVEN THE POTENTIAL FOR A FEW THUNDERSTORMS TO TAP INTO
THE HIGHER CAPE IN POCKETS OF STRONGER HEATING AND BOUNDARY LAYER
DESTABILIZATION AND PRODUCE STRONG TO SEVERE WIND GUSTS. THIS IS
ONLY IF THUNDERSTORMS CAN DEVELOP. KEPT THE CHANCE POPS IN THE
FORECAST FOR NOW. NOT EVEN CONFIDENT ENOUGH TO GO WITH SCATTERED
WORDING.
SHORT TERM...SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE
IS MEDIUM TO HIGH.
SHORT TERM MODELS IN GOOD AGREEMENT WITH SLIDING COLD FRONT
SOUTHWARD THROUGH THE AREA SATURDAY EVENING. LEFT POPS IN FORECAST
FOR AREAS ALONG AND AHEAD OF THE FRONT. INCREASING NORTHEAST WINDS
WITH TIGHTENING PRESSURE GRADIENT BEHIND FRONT WILL BRING COOLER
AND DRIER AIR INTO THE AREA LATER SATURDAY NIGHT INTO SUNDAY. THIS
A RESULT OF HIGH PRESSURE SLIDING SOUTHEAST THROUGH THE CENTRAL
GREAT LAKES REGION.
MODELS ALSO HINTING AT AN AREA OF LOW CLOUDS MOVING SOUTHWESTWARD
THROUGH THE AREA DURING THIS TIME. COLD AIR ADVECTION AND THE
CLOUDS SHOULD KEEP HIGHS IN THE 70S...COOLEST NEAR THE LAKE.
850MB WARM AIR ADVECTION KICKS IN SUNDAY NIGHT AND ESPECIALLY
MONDAY ACROSS THE REGION. BEST FOCUS FOR UPWARD VERTICAL MOTION
WILL REMAIN NORTH OF THE AREA DURING THIS TIME. HOWEVER...AREA
FORECAST SOUNDINGS DO SHOW ELEVATED CAPE INCREASING DURING THIS
TIME. MODELS NOT SHOWING MUCH QPF.
AREA IS ON PERIPHERY OF THE 850MB WARM AIR ADVECTION...SO COULD
NOT COMPLETELY RULE OUT A SHOWER OR STORM...MAINLY MONDAY MORNING.
LEFT LOW END POPS IN FORECAST FOR MONDAY MORNING. MOST OF THE DAY
SHOULD BE DRY. VERY WARM AND HUMID CONDITIONS WILL RETURN
MONDAY...WITH MID TO UPPER 80S INLAND...SOMEWHAT COOLER LAKESIDE.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE IS
MEDIUM TO HIGH.
GFS/ECMWF IN FAIR AGREEMENT WITH BRINGING COLD FRONT TOWARD THE
AREA MONDAY NIGHT...THEN EASTWARD ACROSS THE AREA TUESDAY INTO
TUESDAY NIGHT. CONTINUED HIGHER END CHANCE POPS FOR MAINLY TUESDAY
NIGHT...SLOWLY TAPERING OFF ON WEDNESDAY. VERY WARM AND HUMID
CONDITIONS WILL CONTINUE TUESDAY...WITH MID TO UPPER 80S. COULD BE
WARMER BUT SOME CLOUDS MAY LIMIT HIGHS.
HIGH PRESSURE THEN SLIDES SOUTHEAST INTO THE REGION FOR THE REST
OF THE WEEK...BRINGING COOLER AND LESS HUMID CONDITIONS. QUIET
WEATHER IS EXPECTED.
AVIATION/00Z TAFS/...VFR CONDITIONS THROUGH TNT ACROSS SRN WI. A
MID LEVEL CLOUD DECK WILL DEVELOP LATE TNT WITH A SLIGHT CHANCE OF
LGT SHOWERS.
A FEW ELEVATED THUNDERSTORMS COULD DEVELOP SATURDAY MORNING TOWARD
SOUTHEAST WI. THEN A FEW TO SCATTERED THUNDERSTORMS ARE EXPECTED
IN THE VICINITY OF A COLD FRONT SLOWLY DROPPING DOWN THROUGH
SOUTHERN WI SATURDAY AFTERNOON AND EVENING.
LOW STRATUS CLOUDS POSSIBLE BEHIND THE FRONT SATURDAY NIGHT INTO
SUNDAY MORNING.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&
$$
UPDATE...REM
TONIGHT/SATURDAY AND AVIATION/MARINE...MRC
SATURDAY NIGHT THROUGH FRIDAY...WOOD
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
332 PM CDT THU SEP 5 2013
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 332 PM CDT THU SEP 5 2013
MAIN FORECAST CONCERNS ARE ON HIGH TEMPERATURES ON FRIDAY AND SHOWER
AND THUNDERSTORM CHANCES FRIDAY NIGHT INTO SATURDAY.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED HIGH
PRESSURE CENTERED OVER EASTERN COLORADO WITH A RIDGE EXTENDING NORTH
THROUGH THE DAKOTAS INTO SOUTHERN SASKATCHEWAN. AN UPPER LOW WAS
NOTED JUST OFF OF THE PACIFIC NORTHWEST...WHILE A BROAD TROUGH WAS
IN PLACE OVER EASTERN CANADA. NORTHWEST FLOW ALOFT WAS NOTED OVER
THE UPPER MISSISSIPPI RIVER VALLEY. SEVERAL WEAK EMBEDDED SHORTWAVES
WERE NOTED OVER THE DAKOTAS. THE PRIMARY WAVE WAS LOCATED OVER
WESTERN NORTH DAKOTA...HEADED SOUTHEAST. HIGH PRESSURE WAS
CENTERED OVER THE WESTERN GREAT LAKES WHILE A STATIONARY BOUNDARY
WAS LOCATED OVER THE EASTERN DAKOTAS AND WAS STRETCHING SOUTHEAST
THROUGH CENTRAL IOWA INTO SOUTHERN ILLINOIS.
THE HIGH WILL SLIDE EAST OF THE REGION TONIGHT AS THE SHORTWAVE
APPROACHES FORM THE DAKOTAS/WESTERN MINNESOTA. SOUTHERLY FLOW WILL
INCREASE ON THE BACK SIDE OF THE HIGH USHERING IN A WARMER AND
SLIGHTLY MORE HUMID AIRMASS. 850 MB MOISTURE TRANSPORT INCREASES
ACROSS WESTERN MINNESOTA AND WESTERN IOWA...WHICH SHOULD RESULT IN
THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. THE MOISTURE
TRANSPORT ATTEMPTS TO EDGE INTO NORTHEAST IOWA AND SOUTHEAST
MINNESOTA LATE TONIGHT INTO EARLY FRIDAY MORNING WHICH MAY SUPPORT
AN ISOLATED SHOWER OR THUNDERSTORM. FORECAST SOUNDINGS ARE RATHER
DRY AND WITHOUT A STRONG FORCING MECHANISM HAVE DECIDED TO
MAINTAIN A DRY FORECAST FOR THE OVERNIGHT HOURS. CANNOT RULE OUT
SOME PATCHY VERY SHALLOW FOG IN COULEE AREAS TONIGHT BUT THAT
SHOULD BE THE EXTENT OF IT. THE GRADIENT TIGHTENS OVER THE REGION
TONIGHT AND WINDS FROM 500 TO 1KFT INCREASE TO 16 TO 25KTS...WHICH
SHOULD PROMOTE ENOUGH MIXING TO PREVENT DENSE FOG FORMATION.
FRIDAY WILL BE A WARM AND BREEZY DAY ACROSS THE REGION AHEAD OF A
WEAK COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. PLAN ON
HIGHS RANGING FROM THE LOWER 80S OVER FAR NORTHERN WISCONSIN TO
THE UPPER 80S TO AROUND 90 OVER NORTHEAST IOWA.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 332 PM CDT THU SEP 5 2013
THE FRONT WILL MOVE THROUGH THE FORECAST AREA FRIDAY NIGHT INTO
SATURDAY MORNING BRINGING CHANCES FOR SHOWERS AND STORMS WITH IT.
THERE IS ELEVATED CAPE OVER THE REGION WITH VERY LITTLE TO NO CAP
IN PLACE. LIFTING FROM 800 MB YIELDS NEARLY 700 J/KG CAPE.
ALSO...850 MB MOISTURE TRANSPORT FOCUSES INTO THE AREA SO THERE
SHOULD BE ENOUGH SUPPORT FOR AT LEAST ISOLATED TO SCATTERED
THUNDERSTORMS. THE BEST CHANCES FOR THESE APPEARS TO BE ALONG AND
EAST OF THE MISSISSIPPI RIVER. HIGH PRESSURE GRADUALLY BUILDS INTO
THE AREA LATE SATURDAY AFTERNOON THROUGH SUNDAY. PRECIPITATION
CHANCES WILL SHIFT SOUTHEAST OF THE FORECAST AREA BY LATE SATURDAY
AFTERNOON AS THE HIGHS BUILDS IN. THE HIGH WILL BE CENTERED OVER
LAKE SUPERIOR ON SUNDAY PROVIDING DRY EAST/NORTHEAST FLOW. HAVE
LOWERED DEW POINTS SIGNIFICANTLY ALONG AND NORTHEAST OF THE
INTERSTATE 94 CORRIDOR WHERE DEEP MIXING WILL YIELD AFTERNOON
RELATIVE HUMIDITY VALUES IN THE MID 30S. THE HIGH WILL SLIDE EAST
OF THE REGION SUNDAY NIGHT INTO MONDAY AS A VIGOROUS TROUGH RACES
ACROSS NORTH DAKOTA AND NORTHERN MINNESOTA. VERY WARM IS ADVECTS
NORTHWARD AHEAD OF THIS FEATURE INTO THE FORECAST AREA WITH 925 MB
TEMPERATURES WARMING INTO THE UPPER 20S TO AROUND 30. DECIDED TO
WARM HIGH TEMPERATURES ON MONDAY INTO THE UPPER 80S TO LOWER
90S...CLOSER TO WHAT THE ECMWF IS ADVERTISING. THERE IS THE
POTENTIAL FOR SHOWERS AND STORMS ALONG AND NORTH OF INTERSTATE 90
ON MONDAY SO TEMPERATURES MAY NOT GET THAT WARM ACROSS THESE
AREAS. ZONAL FLOW LOOKS TO SET UP OVER THE REGION ON TUESDAY INTO
TUESDAY NIGHT WITH EMBEDDED SHORTWAVES POSSIBLY GENERATING SOME
SHOWERS AND STORMS OVER THE FORECAST AREA. THE ECMWF IF
ADVERTISING BETTER CHANCES FOR PRECIPITATION ON WEDNESDAY AS A
TROUGH DIVES SOUTH OUT OF CANADA. THE GFS IS NOT NEARLY AS
AGGRESSIVE WITH THIS FEATURE AND BRINGS THE BULK OF THE
PRECIPITATION THROUGH TUESDAY INTO TUESDAY NIGHT WITH THE PASSAGE
OF A COLD FRONT. CONSIDERABLE UNCERTAINTY IN THE FORECAST BEYOND
MONDAY SO CHOSE TO LEAN TOWARD A MODEL CONSENSUS BLEND.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1207 PM CDT THU SEP 5 2013
THE MAIN PROBLEM CONCERNS THE STRATUS DECK AN HOW FAR WEST IT WILL
PROGRESS AND WHEN OR IF IT WILL DISSIPATE. THE 05.14Z RAP SUGGESTS
THIS MOISTURE FIELD WILL MIX OUT THIS AFTERNOON ALLOWING THE
CLOUDS TO BREAK UP AND THAT THIS WILL HAPPEN BEFORE THE CLOUDS
MOVE INTO KRST. THE 05.12Z NAM HANGS ON TO THE MOISTURE FIELD
THROUGH THE ENTIRE PERIOD...SUGGESTING THE CLOUDS WILL PERSIST
INTO TONIGHT BEFORE GETTING LIFTED NORTH OF THE AREA ON THE
BACKSIDE OF THE RIDGE AXIS. LOOKING AT THE LAST FEW SATELLITE
IMAGES...THE AREA OF CLOUDS HAS ESSENTIALLY STOPPED ITS WESTWARD
ADVANCE AND NOW APPEARS TO BE SHRINKING ON THE EAST SIDE AS WELL.
THUS WILL FOLLOW THE RAP TRENDS AND NOT BRING THE CLOUDS INTO
KRST AND SHOW THEM SCATTERING OUT AT KLSE BY MID AFTERNOON. ONCE
THE CLOUDS ARE OUT OF THE WAY...THE HIGH WILL CONTINUE TO SLIDE
OFF TO THE EAST THROUGH THE REMAINDER OF THE PERIOD. THIS WILL
KEEP ENOUGH OF A GRADIENT THROUGH THE NIGHT TO HAVE SOUTHEAST
WINDS BETWEEN 5 AND 10 KNOTS. EXPECT THAT THIS WILL PRECLUDE THE
FORMATION OF ANY VALLEY FOG...BUT CANNOT TOTALLY RULE OUT A LITTLE
BIT OF MVFR FOG FOR A SHORT WHILE LATE TONIGHT INTO EARLY FRIDAY
MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1207 PM CDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM CDT THU SEP 5 2013
CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY
AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN
ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND
SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF
LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER
TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH
CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS
THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES
ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS
NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE
I-94 CORRIDOR.
FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY.
RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES
FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT
LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM
AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI
RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO
FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW
BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH
TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S.
ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN
EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE
NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF
850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE
ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN
MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO
NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA
ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER
MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES
ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY
LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH
JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST
OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS
SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU SEP 5 2013
ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST
OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE
AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND
ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN
MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING
SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB
TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD
YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE
LOCATIONS FLIRTING WITH THE 90 DEGREE MARK.
FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK
SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE
TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL
BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED
SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON
SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR
KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS...
LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES
WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS
THE AREA.
SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM
ONTARIO CANADA INTO THE GREAT LAKES REGION.
LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS
LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN
PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH
INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES
CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA.
WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS
WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND
35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM
SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON
SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY.
THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY
NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE
EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY
INT THE UPPER 70S TO MIDDLE 80S.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1207 PM CDT THU SEP 5 2013
THE MAIN PROBLEM CONCERNS THE STRATUS DECK AN HOW FAR WEST IT WILL
PROGRESS AND WHEN OR IF IT WILL DISSIPATE. THE 05.14Z RAP SUGGESTS
THIS MOISTURE FIELD WILL MIX OUT THIS AFTERNOON ALLOWING THE
CLOUDS TO BREAK UP AND THAT THIS WILL HAPPEN BEFORE THE CLOUDS
MOVE INTO KRST. THE 05.12Z NAM HANGS ON TO THE MOISTURE FIELD
THROUGH THE ENTIRE PERIOD...SUGGESTING THE CLOUDS WILL PERSIST
INTO TONIGHT BEFORE GETTING LIFTED NORTH OF THE AREA ON THE
BACKSIDE OF THE RIDGE AXIS. LOOKING AT THE LAST FEW SATELLITE
IMAGES...THE AREA OF CLOUDS HAS ESSENTIALLY STOPPED ITS WESTWARD
ADVANCE AND NOW APPEARS TO BE SHRINKING ON THE EAST SIDE AS WELL.
THUS WILL FOLLOW THE RAP TRENDS AND NOT BRING THE CLOUDS INTO
KRST AND SHOW THEM SCATTERING OUT AT KLSE BY MID AFTERNOON. ONCE
THE CLOUDS ARE OUT OF THE WAY...THE HIGH WILL CONTINUE TO SLIDE
OFF TO THE EAST THROUGH THE REMAINDER OF THE PERIOD. THIS WILL
KEEP ENOUGH OF A GRADIENT THROUGH THE NIGHT TO HAVE SOUTHEAST
WINDS BETWEEN 5 AND 10 KNOTS. EXPECT THAT THIS WILL PRECLUDE THE
FORMATION OF ANY VALLEY FOG...BUT CANNOT TOTALLY RULE OUT A LITTLE
BIT OF MVFR FOG FOR A SHORT WHILE LATE TONIGHT INTO EARLY FRIDAY
MORNING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
615 AM CDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM CDT THU SEP 5 2013
CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY
AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN
ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND
SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF
LAKE MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER
TO PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH
CENTRAL WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS
THE SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES
ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS
NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE
I-94 CORRIDOR.
FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY.
RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES
FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT
LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM
AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI
RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO
FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW
BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH
TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S.
ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN
EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE
NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF
850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE
ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN
MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO
NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA
ACTIVITY IS EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER
MOISTURE TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES
ACROSS NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY
LOWER LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH
JUST VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST
OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS
SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU SEP 5 2013
ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST
OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE
AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND
ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN
MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING
SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB
TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD
YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE
LOCATIONS FLIRTING WITH THE 90 DEGREE MARK.
FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK
SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE
TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL
BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED
SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON
SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR
KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS...
LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES
WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS
THE AREA.
SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM
ONTARIO CANADA INTO THE GREAT LAKES REGION.
LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS
LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN
PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH
INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES
CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA.
WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS
WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND
35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM
SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON
SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY.
THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY
NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE
EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY
INT THE UPPER 70S TO MIDDLE 80S.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 615 AM CDT THU SEP 5 2013
IN WHAT HAS BEEN A VFR REGIME HAS SOME CHALLENGES THIS MORNING AS
LOW LEVEL STRATUS DECK ADVECTING IN FROM THE EAST IS APPROACHING
MISSISSIPPI RIVER AT DAYBREAK WITH PATCH OF IFR CEILINGS. HOW FAR
WEST IT MIGRATES AND HOW LONG IT MIGHT LAST IS PROBLEMATIC.
MOST WISCONSIN LOCALES DEALING WITH IFR CONDITIONS...WHILE WEST OF
THE RIVER VFR CONDITIONS STILL PREVAIL. FEELING IS STRATUS DECK WILL
CONTINUE TO PUSH WEST THIS MORNING AND THEN PROBABLY HANG UP FOR
MUCH OF THE MORNING BEFORE EARLY SEPTEMBER SUN BEGINS TO BREAK IT
UP. SHORT TERM GUIDANCE SUGGEST DRY LAYERS ABOVE IT SHOULD HELP TO
BREAK IT UP SOMETIME THIS MORNING BUT THIS WILL HAVE TO WATCHED.
VFR CONDITIONS SHOULD RETURN LATER IN THE DAY AND AS SOUTHEAST FLOW
DEVELOPS TONIGHT...COULD SEE SOME MVFR VISIBILITIES RETURN AS
MOISTURE REMAINS HUNG UP ALONG BOUNDARY SITTING JUST TO THE SOUTH.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...SHEA
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
346 AM CDT THU SEP 5 2013
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 346 AM CDT THU SEP 5 2013
CURRENT WATER VAPOR COMBINED WITH RAP 500MB ANALYSIS SHOWS A HIGHLY
AMPLIFIED RIDGE IN PLACE JUST EAST OF THE COLORADO/NORTHERN/CANADIAN
ROCKIES WITH OUR AREA IN NORTHWEST FLOW ALOFT. AT THE SURFACE...A
BROAD AREA OF HIGH PRESSURE EXTENDED SOUTHWARD OUT OF ONTARIO CANADA
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY REGION...INTO THE MID AND
SOUTHERN MISSISSIPPI RIVER REGION. EAST/NORTHEAST SURFACE FLOW OFF LAKE
MICHIGAN WAS COMBINING WITH A RATHER HUMID LOWER BOUNDARY LAYER TO
PRODUCE AN EXPANDING STRATUS FIELD ACROSS SOUTHEAST WI/SOUTH CENTRAL
WI. THIS STRATUS MAY PROVE TO BE PROBLEMATIC TODAY ACROSS THE
SOUTHEAST PORTION OF THE FORECAST AREA. OTHERWISE...TEMPERATURES
ACROSS THE AREA EARLY THIS MORNING RANGED FROM THE 40S ACROSS
NORTHERN WI...TO THE MIDDLE AND UPPER 60S ALONG AND SOUTH OF THE
I-94 CORRIDOR.
FOR TODAY...WILL BE WATCHING THIS AFOREMENTIONED STRATUS CLOSELY.
RAP SOUNDINGS SHOW THIS CLOUD THINNING AS THE MORNING PROGRESSES
FROM NORTHEAST TO SOUTHWEST AS HIGH PRESSURE BUILDS OVER THE GREAT
LAKES AND DRIER AIR GETS ENTRAINED INTO THE BOUNDARY LAYER. THE NAM
AND RAP ARE HINTING AT SOME -SHRA ALONG AND WEST OF TE MISSISSIPPI
RIVER THIS AFTERNOON IN DAYTIME HEATING. HOWEVER...THERE IS NO
FORCING MECHANISM TO TRIGGER THESE SHOWERS. WILL KEEP DRY FOR NOW
BUT WARRANTS WATCHING. WITH LIGHT EASTERLY WINDS...LOOK FOR HIGH
TEMPERATURES TODAY IN THE MIDDLE 70S TO THE LOWER 80S.
ATTENTION THEN TURNS TO NORTHWEST FLOW ALOFT TONIGHT WITH AN
EMBEDDED/WEAKENING SHORTWAVE TROUGH HEADING SOUTHEAST THROUGH THE
NORTHERN PLAINS INTO MN. NAM SHOWING AN INCREASING CORRIDOR OF
850-700MB ISENTROPIC LIFT AND MOISTURE TRANSPORT AHEAD OF THIS WAVE
ACROSS THE PLAINS INTO NORTHWEST MN. PLAN ON SOME INCREASE IN
MID-LEVEL CLOUDS/ACCAS ACROSS PORTIONS OF SOUTHEAST MN INTO
NORTHWEST WI ON THE EASTERN FRINGES OF THIS FORCING. ANY SHRA ACTIVITY IS
EXPECTED TO STAY NORTHWEST OF THE AREA TOWARD THE BETTER MOISTURE
TRANSPORT. ANOTHER MITIGATING FACTOR IN SHOWER CHANCES ACROSS
NORTHWEST IS THE VERY-HIGH BASED NATURE OF THE CLOUDS AND DRY LOWER
LEVELS FOR EVAPORATION OF SHOWERS FROM THESE CLOUDS...WITH JUST
VIRGA EXPECTED. BASED ON THIS SIGNAL...WENT WITH A DRY FORECAST
OVERNIGHT. OTHERWISE...SOUTHERLY AIRFLOW AND INCREASING DEW POINTS
SHOULD KEEP OVERNIGHT LOWS UP IN THE 50S TO LOWER 60S.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 346 AM CDT THU SEP 5 2013
ON FRIDAY...WILL BE WATCHING A SURFACE COLD FRONT PUSHING SOUTHEAST
OUT OF CANADA INTO NORTHERN WI THROUGH CENTRAL MN BY LATE IN THE
AFTERNOON. CORRIDOR OF BEST 850-700MB MOISTURE TRANSPORT AND
ISENTROPIC LIFT STAYS NORTH OF THE AREA WITH JUST SOME INCREASE IN
MID/HIGH CLOUDS EXPECTED ACROSS OUR AREA. OF NOTE WILL BE INCREASING
SOUTHWEST WINDS AND WARM AIR ADVECTION INTO OUR AREA WITH 925MB
TEMPERATURE INCREASING INTO THE 25-28C BY AFTERNOON. THIS SHOULD
YIELD HIGH TEMPERATURES IN THE MID-UPPER 80S...WITH A COUPLE
LOCATIONS FLIRTING WITH THE 90 DEGREE MARK.
FOR FRIDAY NIGHT THROUGH SATURDAY...LOOK FOR THE COLD FRONT TO SINK
SLOWLY SOUTHEAST ACROSS THE AREA. CONTINUED 850-700MB MOISTURE
TRANSPORT/ISENTROPIC LIFT AND WEAK CONVERGENCE ALONG THIS FRONTAL
BOUNDARY SHOULD BE SUFFICIENT FOR ISOLATED-SCATTERED
SHOWER/THUNDERSTORMS. OF NOTE THOUGH IS A FAIRLY STRONG CAP ON
SATURDAY INDICATED BY THE NAM SOUNDING WHICH MAY LIMIT CONVECTION OR
KEEP IT VERY ELEVATED AND SPARSE IN NATURE. EVEN WITH CLOUDS...
LOOKING FOR HIGHS IN THE 80S. LINGERING SHOWER/THUNDERSTORM CHANCES
WILL BE SEEN SATURDAY NIGHT MAINLY SOUTH OF I-90 AS THE FRONT EXITS
THE AREA.
SUNDAY LOOKS DRY AND SLIGHTLY COOLER AS HIGH PRESSURE BUILDS IN FROM
ONTARIO CANADA INTO THE GREAT LAKES REGION.
LOOK FOR THE HIGH TO SLIDE INTO THE NORTHEAST U.S. SUNDAY NIGHT AS
LOW PRESSURE PUSHES OUT OF THE INTERMOUNTAIN WEST INTO THE NORTHERN
PLAINS. THIS PUSHES A WARM FRONT INTO MN/IA AFTER MIDNIGHT WITH
INCREASING 850MB MOISTURE TRANSPORT NOSING INTO THE AREA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. SHOWER AND THUNDERSTORM CHANCES
CONTINUE THROUGH MONDAY AS THE WARM FRONT PUSHES THROUGH THE AREA.
WILL HAVE TO WATCH FOR A SEVERE THREAT DURING THIS TIME FRAMES AS
WELL WITH THE GFS INDICATING 1000-1500J/KG 0-1KM MLCAPE WITH AROUND
35KT OF 0-3KM SHEAR SUNDAY NIGHT AND 2000-2500J/KG AND 25-30KT 0-3KM
SHEAR ON MONDAY. PLAN ON HIGHS IN THE MID 70S/LOWER 80S ON
SUNDAY...AND UPPER 70S/MIDDLE 80S MONDAY.
THE GFS AND ECMWF SHOW A COLD FRONT PUSHING INTO THE AREA MONDAY
NIGHT AND HANGING UP ACROSS THE AREA THROUGH WEDNESDAY FOR A
CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS TUESDAY ARE
EXPECTED TO TOP OFF AGAIN IN THE 80S...COOLING SLIGHTLY ON WEDNESDAY
INT THE UPPER 70S TO MIDDLE 80S.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT
1143 PM CDT WED SEP 4 2013
THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL DEVELOPMENT
OF MVFR TO IFR STRATUS OVERNIGHT INTO TOMORROW MORNING. THIS
STRATUS HAS STARTED TO FORM ACROSS PORTIONS OF EASTERN WISCONSIN
OVER THE PAST FEW HOURS. SOME OF THESE MID LEVEL CLOUDS IN THE
3-6KFT RANGE HAVE SNUCK INTO WESTERN WISCONSIN ALREADY AND WILL
LIKELY PERSIST INTO TOMORROW. THE QUESTION IS IF/WHEN THE
MVFR/IFR STRATUS WILL MAKE IT INTO LSE/RST. WITH THE LOW STRATUS
STILL ALONG LAKE MICHIGAN AND THE LAST FEW RUNS OF THE RAP MODEL
SHOWING THIS HIGHER RH GETTING IN LATER...HAVE DECIDED TO KEEP THE
LOW CONDITIONS IN THE TAF SITES...BUT DELAY IT A FEW HOURS THIS
MORNING. THESE CONDITIONS SHOULD QUICKLY IMPROVE THROUGH THE LATE
MORNING HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DAS
LONG TERM...DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT WED SEP 4 2013
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 337 PM CDT WED SEP 4 2013
MAIN FORECAST CONCERNS IN THE SHORT TERM ARE ON TEMPERATURES AND
CLOUD COVER TONIGHT INTO THURSDAY MORNING.
LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED RIDGING
ACROSS ANCHORED OVER THE ROCKIES. TWO UPPER LOWS NOTED...ONE
CENTERED OVER THE EASTERN SHORE OF HUDSON BAY...AND THE OTHER WAS
JUST EDGING INTO THE PACIFIC NORTHWEST. A WEAK COLD FRONT
STRETCHED FROM CENTRAL MINNESOTA ACROSS CENTRAL WISCONSIN EAST
THROUGH NORTHERN LOWER MICHIGAN AND WAS SLOWLY DRIFTING SOUTH.
THERE HAS NOT BEEN ANY PRECIPITATION ASSOCIATED WITH THE FRONT
JUST A SLIGHT INCREASE IN CLOUD COVER.
SURFACE HIGH PRESSURE WILL BUILD INTO THE FORECAST AREA TONIGHT AS
THE COLD FRONT SLIDES SOUTH INTO CENTRAL IOWA AND SOUTHERN ILLINOIS.
THE STRATUS CURRENTLY OVER NORTHERN WISCONSIN...SLIPS SOUTHWEST
TONIGHT. LINGERING MOISTURE CENTERED AROUND 850 MB...WITH AN
ADDITIONAL POCKET LOCATED IN THE 700-450 MB LAYER...MAY BE ENOUGH TO
GENERATE SOME CLOUD COVER TONIGHT OVER NORTHEAST IOWA....SOUTHEAST
MINNESOTA...AND SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SUGGEST THE
LOWER LEVEL MOISTURE WILL DRY OUT AS THE HIGH BUILDS IN. IF THE
CLOUD COVER LINGERS IT WILL HAVE AN IMPACT ON FOG POTENTIAL AND
TEMPERATURES OVERNIGHT. PLAN ON PARTLY CLOUDY TO MOSTLY CLEAR SKIES
TONIGHT WITH LOW TEMPERATURES RANGING FROM THE UPPER 30S TO LOWER 40S
OVER NORTHERN WISCONSIN TO THE MID TO UPPER 50S ACROSS NORTHEAST
IOWA.
HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY
PROVIDING DRY AND QUIET WEATHER. THE MAIN CONCERN WILL BE ON
AFTERNOON DEWPOINTS...ESPECIALLY CLOSER TO THE CENTER OF THE HIGH
OVER CENTRAL INTO NORTH CENTRAL WISCONSIN. FORECAST SOUNDINGS SHOW
DRY AIR ALOFT WITH DEEP MIXING TO NEARLY 875 MB. LOOKING UPSTREAM
ACROSS UPPER MICHIGAN AND SOUTHERN ONTARIO...DEWPOINTS ARE ONLY IN
THE UPPER 30S TO LOWER 40S AND THIS AIR IS ADVECTING SOUTHWARD. HAVE
LOWERED AFTERNOON DEWPOINTS INTO THE LOWER 40S OVER WEST CENTRAL
THROUGH CENTRAL WISCONSIN WHERE DEEP MIXING SHOULD EASILY YIELD THESE
AFTERNOON VALUES. THIS WOULD PRODUCE RELATIVE HUMIDITY VALUES IN
THE 27 TO 30 PERCENT RANGE. THERE WILL NOT BE MUCH WIND UNDER THE
HIGH WITH WIND MAINLY LIGHT AND VARIABLE AT 5 MPH OR LESS OVER THESE
AREA. OTHERWISE...PLAN ON SKIES RANGING FROM PARTLY TO MOSTLY CLOUDY
OVER SOUTHEAST MINNESOTA INTO NORTHEAST IOWA...TO MOSTLY SUNNY OVER
NORTH CENTRAL WISCONSIN. A WEAK SHORTWAVE LOOKS TO MOVE ACROSS AREAS
ALONG AND WEST OF THE MISSISSIPPI RIVER WITH THE MAIN IMPACT BEING
AN INCREASE IN CLOUD COVER.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 337 PM CDT WED SEP 4 2013
THE HIGH WILL SLIDE EAST INTO THE EASTERN GREAT LAKES THURSDAY NIGHT
INTO FRIDAY. A COLD FRONT IS EXPECTED TO PUSH INTO NORTHWEST
MINNESOTA AND EASTERN SOUTH DAKOTA BY FRIDAY AFTERNOON. SOUTHERLY
FLOW WILL INCREASE ACROSS THE AREA ON FRIDAY AS THE FRONT APPROACHES
HELPING TO USHER IN A WARMER AND SLIGHTLY MORE HUMID AIRMASS. 925 MB
TEMPERATURES WARM TO AROUND 25 ACROSS WESTERN AND CENTRAL WISCONSIN
AND TO THE UPPER 20S ACROSS PORTIONS OF NORTHEAST IOWA AND SOUTHEAST
MINNESOTA. HIGH TEMPERATURES ARE EXPECTED TO WARM INTO THE MID
80S...WITH A FEW UPPER 80S POSSIBLE ALONG THE MISSISSIPPI RIVER
VALLEY AND CLOSER TO THE INTERSTATE 35 CORRIDOR. FORECAST MODELS ARE
ADVERTISING A WEAK SHORTWAVE MOVING ACROSS THE EASTERN DAKOTAS AND
PUSHING INTO THE UPPER MISSISSIPPI RIVER VALLEY LATE THURSDAY NIGHT
INTO EARLY FRIDAY MORNING. 850 MB MOISTURE TRANSPORT IS WEAK AND
FOCUSED INTO SOUTHWEST MINNESOTA AND WESTERN IOWA THURSDAY EVENING
THEN ATTEMPTS TO SHIFT EAST INTO THE AREA EARLY FRIDAY MORNING.
THERE ISN/T MUCH UPPER LEVEL SUPPORT FOR PRECIPITATION SO DECIDED TO
MAINTAIN A DRY FORECAST DURING THIS TIMEFRAME. THE FRONT IS EXPECTED
TO PUSH SOUTHEAST FRIDAY NIGHT INTO SATURDAY POSSIBLY INTERACTING
WITH WEAK UPPER LEVEL IMPULSES IN NORTHWEST FLOW ALOFT. THIS WILL
BRING SLIGHT CHANCES FOR SHOWERS AND STORMS TO THE FORECAST AREA
FRIDAY NIGHT INTO SATURDAY. THE PACIFIC NORTHWEST TROUGH FINALLY
MOVES EAST ACROSS THE NORTHERN PLAINS SUNDAY NIGHT THROUGH MONDAY
NIGHT BREAKING DOWN THE PERSISTENT RIDGING OVER THE UPPER MIDWEST.
THIS WILL BRING CHANCES FOR SHOWERS AND STORMS TO THE FORECAST
AREA...ESPECIALLY SUNDAY NIGHT INTO MONDAY NIGHT. WARM SOUTHERLY
FLOW WILL CONTINUE INTO EARLY NEXT WEEK. HIGHS WILL REMAIN WELL
ABOVE NORMAL THROUGH THE WEEKEND WITH SATURDAY LOOKING TO BE THE
WARMEST DAY WITH HIGHS IN THE MID TO UPPER 80S. THE WARM
TEMPERATURES WILL CONTINUE THROUGH THE MIDDLE OF NEXT WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1143 PM CDT WED SEP 4 2013
THE MAIN FOCUS AT THE TAF SITES IS WITH THE POTENTIAL DEVELOPMENT
OF MVFR TO IFR STRATUS OVERNIGHT INTO TOMORROW MORNING. THIS
STRATUS HAS STARTED TO FORM ACROSS PORTIONS OF EASTERN WISCONSIN
OVER THE PAST FEW HOURS. SOME OF THESE MID LEVEL CLOUDS IN THE
3-6KFT RANGE HAVE SNUCK INTO WESTERN WISCONSIN ALREADY AND WILL
LIKELY PERSIST INTO TOMORROW. THE QUESTION IS IF/WHEN THE
MVFR/IFR STRATUS WILL MAKE IT INTO LSE/RST. WITH THE LOW STRATUS
STILL ALONG LAKE MICHIGAN AND THE LAST FEW RUNS OF THE RAP MODEL
SHOWING THIS HIGHER RH GETTING IN LATER...HAVE DECIDED TO KEEP THE
LOW CONDITIONS IN THE TAF SITES...BUT DELAY IT A FEW HOURS THIS
MORNING. THESE CONDITIONS SHOULD QUICKLY IMPROVE THROUGH THE LATE
MORNING HOURS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...WETENKAMP
LONG TERM...WETENKAMP
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
359 AM MDT SAT SEP 7 2013
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
ISOLATED THUNDERSTORMS FIRING ACROSS PORTIONS OF NORTHEAST ARIZONA
THIS MORNING...BASICALLY SOUTH OF MEXICAN HAT...AND ALONG THE
UNCOMPAHGRE PLATEAU SOUTH AND EAST OF GATEWAY. THE ARIZONA ACTIVITY
APPEARS TO BE ASSOCIATED WITH WEAK WAVE LIFTING NORTH NORTHWEST
ACROSS THAT AREA...WHICH SHOWS UP NICELY IN POT VORT FIELDS ON THE
00Z NAM AND GFS. THIS WAVE WILL CONTINUE TRACKING TOWARD THE FOUR
CORNERS THIS MORNING...BEFORE DAMPENING OUT SHORTLY AFTER SUNRISE.
THE CELLS EAST OF GATEWAY ALONG THE UNCOMPAHGRE PLATEAU APPEAR TO
BE FIRING ALONG AN OLD OUTFLOW BOUNDARY FROM LAST EVENING THAT WAS
EVIDENT ON RADAR IMAGERY EARLIER THIS MORNING. LIGHTNING ACTIVITY
HAS BEEN ON THE INCREASE OVER THE PAST HOUR AND LIKELY WILL
CONTINUE FOR ANOTHER COUPLE HOURS.
HRRR DOING A DECENT JOB WITH PICKING UP THIS ACTIVITY AND DRIVING
IT NW AND N THIS MORNING...ENDING AROUND 14Z OR SHORTLY AFTER
SUNRISE. THIS SOLUTION REASONABLE AND WILL GEAR POPS IN THIS
DIRECTION...BUT BACK OFF AREAL COVERAGE DISPLAYED IN THE HRRR AS
IT APPEARS TO BE A BIT AGGRESSIVE ACROSS SE UTAH. ONCE THIS
ACTIVITY DIMINISHES...WILL TAKE A FEW HOURS TO RE-FIRE
CONVECTION...BUT IT WILL AND FOCUS FOR THE AFTERNOON HOURS WILL BE
ACROSS THE HIGHER TERRAIN AND PORTIONS OF SOUTHEAST UTAH AS THE
DEEPER PLUME NUDGES EAST A BIT AS THE UPPER LOW ACROSS THE PACNW
STARTS TO FEEL THE INFLUENCE OF KICKING SYSTEM MOVING INTO WESTERN
CANADA. THINGS GET A LOT MORE INTERESTING SUNDAY AND MONDAY...
WHICH IS DISCUSSED BELOW AS THE PLUME LEANS OVER AND INTO OUR
FORECAST AREA. UNTIL THEN...ANOTHER HOT DAY WITH TEMPERATURES
RUNNING 5 TO 10 DEGREES ABOVE NORMAL FOR AFTERNOON HIGHS.
TONIGHT THE UPPER LOW TRACKS INTO THE NORTHERN ROCKIES DRAGGING A
TROUGH INTO THE WESTERN GREAT BASIN. IN TIGHTENING SW FLOW
ALOFT...MOISTURE AND LOW LEVEL CONVERGENCE INCREASE IN SE UTAH
OVERNIGHT. SO SOME THUNDERSTORMS ARE EXPECTED TO PERSIST OVERNIGHT
PERHAPS SPREADING INTO NE UTAH AND FAR WESTERN COLORADO. CLOUDS
AND WINDS WILL KEEP OVERNIGHT LOW TEMPERATURES ABOVE NORMAL.
SUNDAY THE PACIFIC TROUGH SHIFTS INTO CENTRAL UTAH. ONE INCH
PRECIPITABLE WATER VALUES REACH INTO THE NORTHERN CWA. A WEAK
SURFACE COLD FRONT WORKS ACROSS THE CO-WY BORDER IN THE AFTERNOON
PROVIDING A FOCUS FOR CONVECTION. WIDESPREAD CLOUDY SKIES WILL
LOWER AFTERNOON TEMPERATURES TO WITHIN A FEW DEGREES OF NORMAL.
GUSTY AFTERNOON WINDS EXPECTED DUE TO GRADIENT PLUS CONVECTIVE
COMPONENTS. SOME MID-LEVEL COOLING WILL INCREASE INSTABILITY
ESPECIALLY OVER NE UT-FAR NW CO.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
SUNDAY NIGHT THROUGH MONDAY NIGHT...THE UPPER LOW TRACKS ONTO THE
NORTHERN PLAINS ON MONDAY LEAVING A WEAK TROUGH OVER THE GREAT
BASIN. THE 40KT JET TAIL TRACKS THROUGH SOUTHERN WYOMING SUNDAY
NIGHT LEAVING A SECOND STRONGER COOL FRONT LAYING WEST TO EAST NEAR
THE WYOMING BORDER ON MONDAY. WITH THE WET BULB ZERO LEVEL BELOW
14KFT...HAIL IS POSSIBLE WITH THE STRONGEST STORMS. TEMPERATURES
FALL TO NEAR/SOUTH OR BELOW/NORTH NORMAL ON MONDAY. DRIER AIR
TRIES TO INVADE NE UTAH MONDAY NIGHT.
THE STAGNANT RIDGE OVER THE PLAINS AND LOW ACROSS THE PACNW
PATTERN WILL BE BREAKING DOWN MONDAY AND TUESDAY...WITH LONG WAVE
TROUGH FINALLY PUSHING EAST ACROSS THE ROCKIES. THIS WILL DRIVE A
LITTLE COOLER AIR INTO THE REGION AS TEMPERATURES DROP BACK TO
MORE SEASONAL VALUES. HOWEVER...CONVECTIVE POTENTIAL WILL REMAIN
IN PLAY FOR MUCH OF THE WEEK AS THE BREAK DOWN AND SWEEP OUT OF
MOISTURE WILL BE SHORT-LIVED WITH THE PLAINS RIDGE REBUILDING BY
THURSDAY. THIS KEEPS THE MONSOON ACTIVE FOR A FEW MORE DAYS WITH
ANOTHER SURGE OF MOISTURE LIFTING ACROSS THE FORECAST AREA AS WE
CLOSE OUT THE WEEK. SO UNSETTLED CONDITIONS WILL CONTINUE WITH
SLIGHTLY MODERATION FROM THE PERSISTENT HEAT THE REGION HAS BEEN
EXPERIENCING.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 358 AM MDT SAT SEP 7 2013
ISOLATED THUNDERSTORMS WILL CONTINUE THROUGH THIS MORNING...AND
BECOME MORE WIDESPREAD THIS AFTERNOON. GUSTY AND ERRATIC OUTFLOW
WINDS...HEAVY RAIN AND SMALL HAIL WILL BE ASSOCIATED WITH STRONGER
THUNDERSTORMS THROUGH 03Z THIS EVENING. MOISTURE WILL CONTINUE
TO SURGE BACK INTO THE REGION AFTER 06Z TONIGHT WITH SHOWERS
LINGERING THROUGH THE NIGHT. EXPECT LOCAL MVFR CIGS AND VSBYS NEAR
THE STRONGER THUNDERSTORMS TODAY...ESPECIALLY ACROSS THE
MOUNTAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...JDC
AREA FORECAST DISCUSSION
NWS MIAMI FL
141 AM EDT SAT SEP 7 2013
.AVIATION...
FOR THE SHORT TERM...THERE ARE SOME THUNDERSTORMS IN THE NEAR
SHORE ATLANTIC WATERS TO THE EAST OF TERMINAL TPBI AND SHOWERS
THAT WILL LIKELY IMPACT THE TERMINAL FOR ABOUT THE NEXT 15 TO 30
MINUTES WITH PERIODS OF SUB-VFR CONDITIONS POSSIBLE AND WITH VERY
BRIEF IFR CONDITIONS POSSIBLE IN THIS TIME FRAME. THE CONVECTION
AFFECTING TERMINAL KPBI IS STARTING TO BREAK UP WITH VCTS
ASSIGNED UNTIL 07Z...WILL AMEND AS NECESSARY. OTHERWISE...WITH
EASTERLY FLOW ACROSS THE ATLANTIC WATERS AND LINGERING BOUNDARIES
FROM CONVECTION EARLIER THIS EVENING A FEW SHOWERS AND/OR ISOLATED
THUNDERSTORMS COULD POP UP BUT MAINLY VFR CONDITIONS EXPECTED FOR
THE REMAINING EAST COAST TERMINALS AND TERMINAL KAPF THE REMAINING
EARLY MORNING HOURS.
60
&&
.PREV DISCUSSION... /ISSUED 847 PM EDT FRI SEP 6 2013/
UPDATE...
ALTHOUGH IT WAS A LATE START FOR THE AFTERNOON SHOWERS AND
STORMS...A LARGE AREA OF HEAVY SHOWERS AND STORMS HAS DEVELOPED
AND BECOME FOCUSED OVER THE GULF COAST AREAS FROM NAPLES TO
EVERGLADE CITY TO CENTRAL COLLIER COUNTY THIS EVENING. THE LATEST
RADAR SCAN ESTIMATED TOTALS RANGING FROM HALF OF AN INCH OVER THE
BULK OF THIS AREA WITH ISOLATED AMOUNTS AS HIGH AS 2.5". THE
LATEST HRRR MODEL REFLECTIVITIES LINE UP WELL WITH THIS ACTIVITY
AND GENERALLY CONTINUES TO SUPPORT THIS COVERAGE WELL INTO THE
LATE EVENING HOURS BEFORE DISSIPATING. IF THIS VERIFIES...AN
ADDITIONAL HALF OF AN INCH TO ONE INCH WITH LOCALLY HIGHER AMOUNTS
WILL BE EXPECTED. THE LATEST FORECAST PACKAGE HAS BEEN UPDATED TO
REFLECT THESE LATEST TRENDS. OTHERWISE...THE PREVIOUS FORECAST
REMAINS ON TRACK THIS EVENING.
PREV DISCUSSION... /ISSUED 736 PM EDT FRI SEP 6 2013/
AVIATION...
VFR PREVAILING AT ALL TERMINALS. VCTS ONLY FOR KAPF THIS EVENING
DUE TO THE ACTIVITY ALREADY NEARBY. EXPECT THIS TO DISSIPATE BY
04Z. VCSH WILL POSSIBLY DEVELOP NEAR ALL EASTERN TERMINALS BY
07/16Z AND WEST COAST SEA BREEZE DEVELOPING BY 07/18Z. VCTS WILL
BE POSSIBLE NEAR KAPF BY THAT TIME ALSO.
PREV DISCUSSION... /ISSUED 230 PM EDT FRI SEP 6 2013/
TYPICAL SUMMER TIME WEATHER THIS WEEKEND BEFORE DRIER
CONDITIONS EARLY NEXT WEEK...
SHORT TERM...
THE EAST AND WEST COAST SEA BREEZES HAVE DEVELOPED EARLY THIS
AFTERNOON WITH THE EAST COAST SEA BREEZE PUSHING ACROSS THE
INTERIOR AREAS. THE EAST COAST SEA BREEZE WILL CONTINUE TO PUSH
WEST ACROSS SOUTH FLORIDA THROUGH THE AFTERNOON HOURS...AS THE
WEST COAST SEA BREEZE REMAINS OVER THE WEST COAST METRO AREAS. AT
THE SAME TIME...A TROUGH OF LOW PRESSURE OVER NORTH FLORIDA WILL
CONTINUE TO MOVE SOUTH INTO CENTRAL FLORIDA. THIS WEATHER PATTERN
WILL ALLOW FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP OVER THE INTERIOR AND WEST COAST METRO AREAS THIS
AFTERNOON INTO EARLY THIS EVENING...WITH ISOLATED SHOWERS ONLY FOR
THE EAST COAST METRO AREAS. SO WILL KEEP THE 30 TO 50 PERCENT POPS
IN PLACE FOR THE INTERIOR AND WEST COAST METRO AREAS THROUGH EARLY
THIS EVENING...WITH ONLY A 20 PERCENT POPS OVER THE EAST COAST
METRO AREAS OF SOUTH FLORIDA.
THE TROUGH OF LOW PRESSURE WILL REMAIN NEARLY STATIONARY TONIGHT
OVER CENTRAL FLORIDA...BEFORE MOVING SLOWLY SOUTH INTO THE LAKE
OKEECHOBEE AREA ON SATURDAY AND THROUGH SOUTH FLORIDA ON SUNDAY.
THIS WILL KEEP THE STEERING FLOW OVER SOUTH FLORIDA IN A LIGHT
NORTHEAST DIRECTION ALONG WITH THE SEA BREEZE DEVELOPMENT EACH DAY
ALONG BOTH COAST. SO THE SCATTERED POPS WILL REMAIN OVER THE
INTERIOR AND WEST COAST METRO AREAS WITH ISOLATED POPS OVER THE
EAST COAST METRO AREAS EACH DAY THIS WEEKEND. THE THREAT OF
THUNDER WILL ALSO BE FOCUS MAINLY OVER THE INTERIOR AND WEST COAST
METRO AREAS EACH DAY THIS WEEKEND..BUT THE EAST COAST METRO AREAS
COULD SEE A THUNDERSTORM OR TWO.
THE 500 MB TEMP WILL ALSO REMAIN VERY COLD FOR THIS TIME OF YEAR
IN THE -8C TO -9C OVER SOUTH FLORIDA. THIS WILL ALLOW FOR SOME OF
THE STORMS EACH DAY THIS WEEKEND TO BECOME STRONG OVER SOUTH
FLORIDA ESPECIALLY WHERE THE SEA BREEZES COLLIDE EACH DAY. THE
PRIMARY IMPACTS FROM THE STRONG STORMS WILL MORE LIKELY BE
LIGHTNING STRIKES, GUSTY WINDS, AND HAIL. SO WILL MENTION THIS IN
THE AFTERNOON HWO PACKAGE.
LONG TERM...
THE TROUGH OF LOW PRESSURE WILL MOVE INTO THE FLORIDA KEYS EARLY
NEXT WEEK BEFORE MOVING BACK UP INTO SOUTH FLORIDA FOR THE MIDDLE
OF NEXT WEEK...AS AN UPPER LEVEL LOW DEVELOPS OVER THE WESTERN
ATLANTIC WATERS. THIS WILL ALLOW FOR SOME DRIER AIR TO WORK INTO
SOUTH FLORIDA FROM THE NORTH EARLY NEXT WEEK...BEFORE MOISTURE
RETURNS TO THE AREA FOR MIDDLE OF NEXT WEEK. THEREFORE...THE POPS
FOR EARLY NEXT WEEK HAVE BEEN LOWER TO SLIGHT CHANCE OVER MOST
OF SOUTH FLORIDA EXCEPT LOW END CHANCE OVER THE WESTERN AREAS.
FOR MIDDLE OF NEXT WEEK...THE POPS WILL REMAIN IN THE CHANCE CAT
OVER SOUTH FLORIDA.
AVIATION...
A WEAK TROUGH IS TRYING TO MAKES ITS WAY INTO SOUTH FLORIDA THIS
AFTERNOON. THIS SHOULD ACT TO ENHANCE CONVECTION IN THE WESTERN
HALF OF THE AREA. THE SEA BREEZE WILL KEEP THE EAST COAST CLEAR OF
MOST CONVECTION, ALTHOUGH AN ISOLATED SHOWERS MAY STILL TRY TO
FORM. GIVEN THIS, HAVE KEPT ANY SHRA/TSRA OUT OF THE EASTERN SITES
THIS AFTERNOON. FOR KAPF, HAVE DELAYED VCTS FOR A FEW HOURS AS THE
MODELS INDICATE IT WILL BE MORE TOWARDS THE MID AFTERNOON BEFORE
CONVECTION AFFECTS NAPLES. HOWEVER, THIS COULD BE OFF A LITTLE, SO
VCTS MAY NEED TO ADDED, OR EVEN DELAYED SOME, BASED ON DEVELOPMENT.
WINDS WILL BE GENERALLY EASTERLY THIS AFTERNOON, WITH THE
EXCEPTION OF KAPF, WHERE THE GULF BREEZE IS EXPECTED TO JUST MAKE
IT PAST THE AIRPORT. TONIGHT, WINDS WILL LIGHTEN AND GO VARIABLE
IN MANY LOCATIONS. THEY WILL ONCE AGAIN BECOME EASTERLY TOMORROW
BETWEEN 5 AND 10 KTS.
MARINE...
THE WINDS WILL REMAIN FROM THE EAST NORTHEAST AT 10 KNOTS OR LESS
THIS WEEKEND INTO EARLY NEXT WEEK OVER ALL OF SOUTH FLORIDA
WATERS. THIS WILL KEEP THE SEAS IN BOTH THE ATLANTIC AND GULF
WATERS AT 2 FEET OR LESS. SO BOATING CONDITIONS WILL BE GOOD OVER
ALL OF SOUTH FLORIDA WATERS OUTSIDE OF ANY SHOWERS AND THUNDERSTORMS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 89 77 88 77 / 40 20 20 10
FORT LAUDERDALE 89 79 89 79 / 40 20 20 10
MIAMI 90 78 89 78 / 50 20 20 10
NAPLES 91 74 91 74 / 50 30 30 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...23/SK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
142 AM EDT SAT SEP 7 2013
.SYNOPSIS...
A WEAK COLD FRONT WILL CONTINUE TO PUSH SOUTH OF THE AREA THIS
EVENING WITH HIGH PRESSURE BUILDING FROM THE NORTH AND EXTENDING
ACROSS THE AREA THROUGH THIS WEEKEND. A BACKDOOR COLD FRONT WILL
APPROACH FROM THE NORTH SUNDAY AND BECOME STATIONARY NEAR OR JUST
NORTH OF THE AREA MONDAY BEFORE DISSIPATING. HIGH PRESSURE WILL
THEN PREVAIL THROUGH THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A HIGHLY AMPLIFIED AND DEEP LAYERED ANTICYCLONE WILL REMAIN
POSITIONED IN THE CENTRAL PLAINS/ROCKIES...AS A LOW AMPLITUDE
SHORT WAVE DROPS SE THROUGH THE MEAN LONG WAVE TROUGH ALONG THE
EASTERN SEABOARD. AT THE SURFACE AN ELONGATED REGION OF HIGH
PRESSURE TO THE NORTH WILL CONTINUE TO BUILD INTO THE
REGION...BRINGING WITH IT CONSIDERABLE DRY AIR ABOVE THE FIRST
MILE OR SO OF THE TROPOSPHERE.
EARLY MORNING RADAR IMAGERY DEPICTS CONVECTION SHIFTING SOUTHWARD
JUST OFF THE SOUTH CAROLINA COAST DUE TO JUST ENOUGH LOW LEVEL
MOISTURE ALONG WITH SOME ISENTROPIC LIFT ON THE 295K AND 300K
SURFACES. WHILE TRAJECTORIES GENERALLY SUGGEST THAT THEY WILL
REMAIN OVER THE ATLANTIC WHERE WHAT LITTLE LOW LEVEL CONVERGENCE
AND LIFT WILL BE FOUND...SOME OF THE HIGHER RESOLUTION MESOSCALE
MODELS SUCH AS THE HRRR SHOW SOME JUST BRUSHING COASTAL AREAS. AS A
RESULT...HAVE ADDED MENTION OF A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS FOR IMMEDIATE COASTAL AREAS THROUGH DAYBREAK.
OTHER THAN SOME STRATOCUMULUS OVER COASTAL AREAS...LITTLE CLOUD
COVER AND MOSTLY CALM WINDS INLAND WILL CONTINUE TO PROMOTE DECENT
RADIATIONAL COOLING. BUT GIVEN THAT GEOSTROPHIC WINDS DO HOLD
AROUND 10-15 KT WE WON/T GO TOO LOW...WITH MINIMUM TEMPS GENERALLY
CLOSE TO SEASONAL LEVELS. 66-70 WEILL BE COMMON INLAND FROM
US-17...WITH LOWER AND MIDDLE 70S CLOSER TO THE COAST WHERE A
LIGHT NE AND EAST WIND WILL EXIST.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
SATURDAY THROUGH MONDAY...PRONOUNCED LONGWAVE TROUGHING WILL
DOMINATE MUCH OF THE EASTERN U.S. THIS WEEKEND BEFORE LIFTING OUT
EARLY NEXT WEEK. AT THE SURFACE...DRY SURFACE HIGH PRESSURE WILL
EXTEND SOUTH ACROSS THE AREA. FORECAST SOUNDINGS INDICATE ONLY
SHALLOW LOW-LEVEL MOISTURE WILL BE PRESENT SATURDAY...WITH THE DEPTH
OF THE BEST LOW-LEVEL MOISTURE INCREASING SUNDAY AND MONDAY AS THE
LOW-LEVEL FLOW BECOMES MORE ONSHORE. THIS WILL RESULT IN VERY SMALL
PROBABILITIES FOR MEASURABLE RAINFALL THROUGH EARLY NEXT WEEK.
SATURDAY LOOKS THE DRIEST WITH NO ACTIVITY...BUT ISOLATED
SHOWERS/TSTMS WILL BE POSSIBLE ACROSS MAINLY SOUTH COASTAL SOUTH
CAROLINA WITH THE SEA BREEZE SUNDAY. THE BACKDOOR FRONT WILL DROP
SOUTH AND BECOME STATIONARY NEAR OR JUST NORTH OF THE AREA MONDAY
MORNING...THUS ITS PROXIMITY COUPLED WITH THE AFTERNOON SEA BREEZE
NECESSITIES KEEPING SLIGHT CHANCE POPS IN PLACE FOR ALL AREAS
MONDAY...ALTHOUGH THE MAJORITY OF THE MODELS KEEP CONDITIONS DRY.
THE ONLY EXCEPTION IS THE GFS WHICH SHOWS QUITE A BIT OF ACTIVITY
FORMING ACROSS MAINLY SOUTHEAST SOUTH CAROLINA. THIS SOLUTION IS
DISCOUNTED FOR NOW.
TEMPERATURES WILL BE SEASONABLE THROUGH THE PERIOD WITH HIGHS IN THE
UPPER 80S TO LOWER 90S WITH LOWS UPPER 60S TO MID 70S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
GOOD MODEL AGREEMENT THIS PERIOD WITH HIGH PRESSURE PREVAILING INTO
THURSDAY BEFORE ANOTHER WEAK COLD FRONT PUSHING INTO THE AREA
FRIDAY. FAIRLY TYPICAL SUMMERTIME PATTERN EXPECTED WITH MOSTLY
ISOLATED AFTERNOON SHOWERS AND THUNDERSTORMS EACH AFTERNOON THROUGH
THURSDAY. RAIN CHANCES SHOULD INCREASE A BIT FRIDAY WITH THE FRONT
IN THE VICINITY. TEMPERATURES SHOULD BE NEAR OR SLIGHTLY ABOVE
NORMAL THROUGH THE PERIOD.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS ARE EXPECTED TO PREVAIL AT KCHS AND KSAV THROUGH
06Z SUNDAY.
EXTENDED AVIATION OUTLOOK...THERE ARE NO CONCERNS WITH A GREATER
THAN 30 PERCENT CONFIDENCE AT THIS TIME.
&&
.MARINE...
TONIGHT...HIGH PRESSURE WILL CONTINUE TO NUDGE FURTHER SOUTH AND
SW. THERE IS ENOUGH OF A PRESSURE GRADIENT TO KEEP EAST AND NE
WINDS UP NEAR 10 OR 15 KT...BEFORE THEY BACK MORE NORTHERLY WITH
LAND BREEZE INFLUENCES LATE. SEAS WON/T CHANGE MUCH,,,HOLDING
AROUND 2 OR 3 FT...A MIX OF SMALL SWELLS AND WIND DRIVEN ENERGY.
SATURDAY THROUGH MONDAY...A STEADY NORTHEAST FLOW WILL DOMINATE
SATURDAY WITH WINDS AROUND 10 KT...POSSIBLY A BIT HIGHER ALONG THE
LAND/SEA INTERACT WITH THE SEA BREEZE. WINDS ARE EXPECTED TO BECOME
MORE ONSHORE SUNDAY AND MONDAY AS THE FLOW-LEVEL FLOW RESPONDS TO
HIGH PRESSURE SHIFTING OFFSHORE. BOTH WINDS AND SEAS LOOK TO REMAIN
WELL BELOW SMALL CRAFT ADVISORY CRITERIA.
TUESDAY AND WEDNESDAY...NO SIGNIFICANT CONCERNS THIS PERIOD. WINDS
MOSTLY 15 KT OR LESS WITH SEAS GENERALLY 3 FT OR LESS.
RIP CURRENTS...WW4 OUTPUT FORECASTS AN UNDERLYING 2 FOOT SWELL
DEVELOPING TONIGHT AND PERSISTING INTO SATURDAY WITH PERIODS
INCREASING TO ABOUT 9 SECONDS. MODEST NORTHEAST WINDS COUPLED WITH
THIS INCREASING SWELL AND INCREASING LUNAR INFLUENCES WILL PRODUCE A
BORDERLINE MODERATE RISK FOR THE GEORGIA BEACHES SATURDAY. OPTED TO
CAP THE RISK AT A HIGH-END LOW RISK FOR NOW GIVEN ITS AFTER THE MAIN
BEACH SEASON...BUT THIS COULD EASILY BE UPPED TO A MODERATE RISK
WITH LATER FORECASTS.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...JAQ
SHORT TERM...ST
LONG TERM...RJB
AVIATION...JAQ/ST
MARINE...
AREA FORECAST DISCUSSION
NWS BUFFALO NY
435 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SUNSHINE MAY BRIEFLY SNEAK IN EARLY THIS MORNING...BUT HIGH CLOUDS
WILL MOVE IN QUICKLY FROM NW-SE. DESPITE THE CLOUDS...THE REGION
SHOULD STAY MOSTLY DRY THROUGH THE MORNING HOURS OUTSIDE OF A FEW
SPRINKLES NORTH OF THE THRU-WAY.
AN AREA OF SHOWERS ACROSS LAKE HURON EARLY THIS MORNING WILL
CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM
LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER
LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A
DIFFLUENT UPPER LEVEL FLOW. PREVIOUS MODEL GUIDANCE DIFFERED ON THE
EXTENT OF SHOWERS WITH THIS FEATURE...BUT NOW THAT RADAR SHOWS IT
HAS DEVELOPED WE CAN HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL
CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD
THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE
ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO
ENTER N OF I-90 THIS AFTERNOON...WITH THESE WEAKENING LATE AFTERNOON
AS THE SHOWERS SLIDE ESE INTO THE FINGER LAKES AND EAST OF LAKE
ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY.
HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY
CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF
LAKE ONTARIO. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM
BUFFALO TO NIAGARA FALLS.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THIS MORNING WITH
MAINLY MID AND HIGH CLOUDS. THE EXCEPTION IS AT JHW...WHERE VSBY
WILL VARY IN GROUND FOG...WHICH SHOULD DISSIPATE AROUND 12Z.
AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS
LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO
BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR
CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP N-S
THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE
MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT
LATE TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS
WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT
AND MONDAY...AS HIGH PRESSURE BUILDS IN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEZ020-041.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS BUFFALO NY
352 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SUNSHINE MAY BRIEFLY SNEAK IN EARLY THIS MORNING...BUT HIGH CLOUDS
WILL MOVE IN QUICKLY FROM NW-SE. DESPITE THE CLOUDS...THE REGION
SHOULD STAY MOSTLY DRY THROUGH THE MORNING HOURS OUTSIDE OF A FEW
SPRINKLES NORTH OF THE THRU-WAY.
AN AREA OF SHOWERS ACROSS LAKE HURON EARLY THIS MORNING WILL
CONTINUE TO TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM
LINK THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER
LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A
DIFFLUENT UPPER LEVEL FLOW. PREVIOUS MODEL GUIDANCE DIFFERED ON THE
EXTENT OF SHOWERS WITH THIS FEATURE...BUT NOW THAT RADAR SHOWS IT
HAS DEVELOPED WE CAN HAVE FAIRLY HIGH CONFIDENCE THAT IT WILL
CONTINUE TO TRACK WITH THE 500 MB FLOW. THE GFS HAS CONSISTENTLY HAD
THE BEST HANDLE ON THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE
ADVECTION OF A FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO
ENTER N OF I-90 THIS AFTERNOON...WITH THESE WEAKENING LATE AFTERNOON
AS THE SHOWERS SLIDE ESE INTO THE FINGER LAKES AND EAST OF LAKE
ONTARIO. THE SOUTHERN TIER SHOULD STAY DRY.
HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY
CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF
LAKE ONTARIO. A DECENT SW BREEZE WILL DEVELOP OFF LAKE ERIE FROM
BUFFALO TO NIAGARA FALLS.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH THIS MORNING WITH ONLY MID-
HIGH CLOUDS. AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL
MOVE ACROSS LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME
LIGHT RAIN TO BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN
THE VFR CATEGORY WITH THIS. THEN ANOTHER ROUND OF SHOWERS WILL DROP
N-S THIS EVENING. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE
MVFR/IFR CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE
TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS
WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT
AND MONDAY...AS HIGH PRESSURE BUILDS IN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEZ020-041.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
153 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT SOUTH OF PENNSYLVANIA TONIGHT AND SATURDAY.
A WEAK COLD FRONT WILL SLIDE ACROSS THE REGION EARLY SUNDAY...
FOLLOWED BY ANOTHER CANADIAN HIGH PRESSURE SYSTEM EARLY NEXT WEEK.
TEMPERATURES SHOULD GRADUALLY TREND WARMER WITH INCREASING
HUMIDITY INTO THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
LATE EVENING SATL IMAGERY SHOWING A BATCH OF CIRRUS WORKING SE INTO
PA IN AREA OF WAA ALOFT AHEAD OF SHORTWAVE DROPPING ACROSS THE E
GRT LKS. BASED ON UPSTREAM TRENDS AND RAP OUTPUT...BELIEVE THERE
WILL BE A FAIR AMT OF CIRRUS ARND TONIGHT...ESP ACROSS THE NW HALF
OF THE STATE. HAVE THEREFORE RAISED TEMPS A BIT...WITH MINS
RUNNING IN THE M40S ACROSS MOST OF THE REGION.
THE DRIEST AIR AND LIGHTEST WINDS ASSOC WITH RETREATING SFC HIGH
PRES SYS WILL BE OVER SOUTHERN PA TONIGHT...SO EXPECT THE COOLEST
TEMPS RELATIVE TO NORMAL TO BE OVR THE SOUTHERN COUNTIES. AS
OCCURRED THIS AM...SOME PATCHY FOG IS POSSIBLE IN A FEW SPOTS
TOWARD DAWN. HOWEVER...TEMPS WILL BE MILDER THAN LAST NIGHT OVR
MOST OF THE REGION...SO ANY FOG SHOULD BE ISOLATED.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
SFC HIGH PRES RIDGE WILL SLIDE SE AND EXTEND FROM THE SOUTHEASTERN
STATES TO THE VA COAST SATURDAY AFTERNOON...ALLOWING A WARMER
SOUTHWESTERLY LLVL FLOW TO DEVELOP ACROSS THE REGION UNDER PARTLY
TO MOSTLY SUNNY SKIES.
A NARROW RIBBON OF SLIGHTLY ANOMALOUS PWAT AIR ALONG AND AHEAD OF
A COLD FRONT MOVING SE ACROSS THE GLAKES WILL EDGE INTO FAR NWRN
PENN TOWARD SAT EVENING. LEFT THE SMALL CHANCE OF A SHOWER IN THE
FCST NEAR THE END 0F THE DAY...BUT THINKING IS THAT SATURDAY WILL
BE ANOTHER IN OUR RECENT STRING OF FINE LATE SUMMER DAYS.
HIGH TEMPS SATURDAY WILL REBOUND TO NEAR OR SLIGHTLY ABOVE
NORMAL...WHICH ARE LOWER TO MID 70S ACROSS THE MTNS...AND NEAR
80F THROUGHOUT THE LOWER SUSQ VALLEY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
CHANCES FOR SHOWERS WILL INCREASE SATURDAY NIGHT ACROSS NORTHERN
ANC CENTRAL SECTIONS OF THE STATE AS A CFRONT SLIDES SE ACROSS
THE COMMONWEALTH. NARROW RIBBON OF ELEVATED PWAT AIR WILL BE
PRESENT BENEATH A REGION OF FAIRLY STRONG UPPER DIVERGENCE/
DIFFLUENT FLOW BETWEEN 2 DISTINCT JET CORES. POPS WILL STAY LOWEST
ACROSS THE SE. LOWS WILL BE NOTICEABLY MILDER...ONLY DROPPING INTO
THE MID TO UPPER 50S...WITH PLENTY OF CLOUDS AND LIGHT WEST BREEZE
ADVECTING IN WARMER/MORE HUMID AIR AHEAD OF THE FRONT.
DRIER AND SLIGHTLY COOLER AIR WILL ADVECT SE INTO THE REGION FOR
SUNDAY...WITH PERIODS OF BKN-OVC STRATO CU CLOUDS AND ISOLATED
SHOWERS - CONCENTRATED ACROSS THE MTNS AND SOUTHERN PENN DURING
THE MORNING.
ANOTHER MAINLY CLEAR...CALM...AND CHILLY NIGHT IS IN STORE FOR
SUNDAY NIGHT AS CANADIAN HIGH PRESSURE DRIFTS SE ACROSS THE LOWER
GLAKES AND INTO NRN PENN BY 12Z MONDAY. PWATS SUNDAY NIGHT WILL FALL
TO BETWEEN 10-15MM OVER THE ENTIRE STATE...ALLOWING TEMPS TO SLIP
BACK INTO THE UPPER 30S ACROSS THE NORTHERN TIER AND NE AND MAINLY
INT HE 40S ELSEWHERE.
MONDAY WILL BE A SUNNY AND PLEASANT DAY WITH LIGHT SOUTH TO SE WIND
AS HIGH PRESSURE DRIFTS EAST TO NEAR THE NEW JERSEY COAST.
A GRADUAL WARM-UP WILL FOLLOW FOR TUESDAY AND WEDNESDAY IN
DEVELOPING WESTERLY ZONAL FLOW AS HIGH PRESSURE BUILDS OVER THE SE
US. TEMPS WILL AGAIN MOVE ABOVE NORMAL.
THE MAIN WEATHER-MAKER FOR LATE NEXT WEEK WILL COME IN THE FORM
OF A STRONG COLD FRONT...AND PRECEDING BAND OF ABOVE NORMAL PWAT
AIR. THIS FRONT WILL LEISURELY CROSS THE STATE LATE WEDNESDAY
NIGHT THROUGH THURSDAY EVE. SCATTERED MAINLY AFTERNOON/EARLY
EVENING SHOWERS AND TSRA WILL OCCUR ALONG AND IN ADVANCE OF THE
CFRONT.
DEEPENING NW FLOW ALOFT RESUMES FOR FRIDAY AND SATURDAY AS THE
UPPER HIGH THAT BRIEFLY VISITS THE SERN U.S. RETROGRADES AND
STRENGTHENS ACROSS THE HIGH PLAINS AND ROCKIES...BRINGING DRIER
AND NOTABLY COOLER AIR BACK INTO PA. LAKE EFFECT/OROGRAPHICALLY
ENHANCED STRATO CU WILL BE POSSIBLE ACROSS THE NRN AND WRN MTNS
OF THE STATE IN THE WAKE OF THE FRONT. PARTLY TO MOSTLY SUNNY
SKIES SHOULD PREVAIL ELSEWHERE.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
SFC HIGH PRES OVR PA AND ADJ STATES TDY WILL YIELD TO A COLD FRONT
PUSHING SEWD FROM THE LWR GRT LKS. THE FRONT WILL MOVE NW-SE THRU
THE AIRSPACE FROM LATE TONIGHT THRU THE DAYLIGHT HOURS ON SUNDAY.
WDLY SCT LGT SHOWERS/SPRINKLES SHOULD ACCOMPANY THE COLD
FRONT...FOLLOWED BY A BAND OF POST-FRONTAL LOW END VFR TO MVFR
CIGS. SFC WNDS WILL SHIFT FROM WSW TO NNW BEHIND THE FRONT. HIGH
PRES RETURNS VFR CONDS FOR MONDAY...BEFORE AN INCREASINGLY MOIST
SLY FLOW AND ASSOCD WARM FRONT THREATENS MVFR CIGS AND ISOLD CONVECTION
FOR TUES. A COLD FRONT PUSHING SEWD FROM THE GREAT LAKES WILL
LKLY BE A FOCUS FOR SCT SHOWERS/TSTMS THRU THE MIDDLE OF NEXT
WEEK.
OUTLOOK...
SUN...VFR WITH SCT SHRA/MVFR CIGS POSSIBLE WITH FROPA.
MON...VFR. NO SIG WX.
TUE/WED...AM FOG PSBL. VFR WITH ISOLD-SCT TSTM IMPACTS PSBL.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
407 AM CDT SAT SEP 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT SEP 7 2013
TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH
THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE
HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE
HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE
MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE
MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH
WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST
AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000
J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM
700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO
BECOME ALL THAT ORGANIZED OR SEVERE.
BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH
ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING
UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX
EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE
BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE
ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY.
QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL
SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN
CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT.
HAVE RAISED SKY COVER IN THE EAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT SEP 7 2013
EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD
BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA.
THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT
ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF
INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY
ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST.
SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW
SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT
INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY
A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM
TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD
MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED
GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH
DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70.
LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES
KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE
UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND
THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING
ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW
LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH
OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND
THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14
CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30
POP IN THAT REGION.
MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD
APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING
AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY
WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF
THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS
HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF
THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST
OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS
COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST.
CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER
MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST
FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING
DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT
ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE
BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT
DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS
WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE
NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND
THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT.
INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND
THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST
FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT
LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL
ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR
INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS.
MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH
PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION
PARALLEL TO THE FRONT.
BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS
NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER
AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO
WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH
HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS
MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A
WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE
RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT
MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE
COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN
SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS
SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY
HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT.
LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR
NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH
OF TEMPERATURES THE FOLLOWING WEEK.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1054 PM CDT FRI SEP 6 2013
MOSTLY VFR THROUGH 08/06Z. AN EXCEPTION MAY BE PATCHY RADIATION
FOG 09Z-14Z IN SOUTHEAST PART OF THE AREA AS FLOW BECOMES LIGHT
AND BEST LOW LEVEL MOISTURE LINGERS...SO HAVE GONE FOR BRIEF MVFR
AT KSUX.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
323 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST PASSING OFF THE
COAST LATER THIS AFTERNOON AND EVENING. A WEAK COOL FRONT WILL
APPROACH FROM THE NORTHWEST LATE TONIGHT BEFORE SLIDING SOUTH
ACROSS THE REGION LATER SUNDAY...AND INTO THE CAROLINAS SUNDAY
EVENING. WEAK HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA BEHIND
THE FRONT SUNDAY NIGHT AND THEN OFFSHORE THE MID ATLANTIC COAST
ON MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 210 AM EDT SATURDAY...
GRADIENT BETWEEN LOWER DEWPOINT AIR TO THE NORTH AND SOMEWHAT
MORE MOIST AIR TO THE SOUTH REMAINS ACROSS THE CENTRAL CWA EARLY
THIS MORNING. THIS IN COMBO WITH WEAK 9H SE UPSLOPE FLOW AND AN
AXIS OF HIGHER THETA-E ALONG THE SRN BLUE RIDGE HAS LED TO THE
DEVELOPMENT OF A STRATO-CU LAYER UNDER THE INVERSION FROM NW NC
INTO THE NEW RIVER VALLEY ATTM. EXPECT THIS CANOPY MAY INCREASE
SOME THROUGH DAYBREAK AS WELL AS FOG ALONG THE PERIMETER GIVEN
RIDGING OVERHEAD SO BEEFED UP CLOUDS/FOG TO INIT BUT STILL DRY.
OTRW WEAK MID LEVEL WAVE RIDING SOUTH THRU WVA WILL DROP
THROUGH THE REGION TODAY AS SURFACE HIGH PRESSURE GETS BUMPED
EAST. THIS SHOULD ALLOW THE LOW LEVEL FLOW TO QUICKLY VEER FROM
SOUTH/SE EARLY TO A MORE WESTERLY COMPONENT DURING THE AFTERNOON
AS THE WAVE ALOFT PASSES AND THE HIGH SLIDES OFFSHORE. LATEST
GUIDANCE RH FIELDS SHOW THIS ENOUGH TO SCOUR OUT RESIDUAL LOW
CLOUDS BY MID OR LATE MORNING WITH ONLY THE HRRR HANGING ONTO
CLOUDS ALONG THE SRN FOOTHILLS A BIT LONGER. THUS APPEARS
BECOMING MOSTLY SUNNY ON TRACK WITH ONLY SOME CU AND HIGH CLOUDS
AROUND WITH THE IMPULSE ALOFT THIS AFTERNOON ONCE ANY LOW DECK
FADES. MODELS DO SHOW A LOBE OF DECENT INSTABILITY AND WEAK
CONVERGENCE FAR SW INTO NW NC LATER THIS AFTERNOON SO AN ISOLD
MOUNTAIN TSRA CANT TOTALLY BE RULED OUT BUT TOO IFFY UNDER DRY
ENTRAINMENT TO INCLUDE MENTION FOR THE MOST PART. OTRW GIVEN A
MORE WESTERLY TRAJECTORY AND 85H WARMING OF A FEW DEGREES DURING
THE DAY...BUMPED UP HIGHS A LITTLE ESPCLY EAST WHERE EXPECT LOW
80S WITH MAINLY 70S ELSW.
NEXT COLD FRONT ACROSS THE GREAT LAKES LATER TODAY WILL BE
APPROACHING FROM THE NORTH LATE TONIGHT AND PERHAPS SPREADING
A PRECEDING BAND OF MID/HIGH CLOUDS IN FROM THE NW OVERNIGHT.
HOWEVER AIR AHEAD OF THE BOUNDARY REMAINS QUITE DRY ALOFT AND
GIVEN A STRONG NW TRAJECTORY THINKING MOSTLY CLEAR OVERALL UNDER
LINGERING HIGH PRESSURE. INCREASING WEST/NW WINDS ALOFT SHOULD
ALSO ACT TO KEEP TEMPS UP SOME ON THE RIDGES AHEAD OF THE
FRONT...WHILE THE VALLEYS AND SPOTS OUT EAST SPILL BACK INTO THE
MID/UPPER 50S FOR LOWS UNDER BETTER RADIATIONAL COOLING.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM EDT SATURDAY...
A COLD FRONT WILL MOVE THROUGH THE REGION ON SUNDAY IN
ASSOCIATION WITH AN UPPER TROUGH PROGRESSING THROUGH NEW ENGLAND.
GUIDANCE FOR THE PAST SEVERAL DAYS HAS FLIP-FLOPPED ON HOW
EXPANSIVE ANY ASSOCIATED PRECIPITATION WILL BE WITH THIS FEATURE
AS IT MOVES THROUGH OUR REGION. THIS MORNING/S FORECAST WILL BE
COMPARABLE TO THE ONE OFFERED YESTERDAY AFTERNOON...WITH SCATTERED
SHOWERS EXPECTED ACROSS THE MOUNTAINS BY THE AFTERNOON WITH
ISOLATED COVERAGE ACROSS ABOUT ONE TIER OF COUNTIES EAST OF THE
CREST OF THE BLUE RIDGE. ISOLATED THUNDERSTORMS ARE ALSO FORECAST.
TEMPERATURES WILL CONTINUE THEIR TREND OF BEING WARMER EACH DAY ON
SUNDAY PRE- COLD FRONT. AROUND 80 TO THE MID 80S ARE EXPECTED
ACROSS THE MOUNTAINS...WITH UPPER 80S COMMON ACROSS THE PIEDMONT.
BEHIND THE FRONT...HIGH PRESSURE WILL BUILD OFF THE MID-ATLANTIC
COAST AND FLOW AROUND THE HIGH WILL GRADUALLY USHER IN
SOUTHWEST FLOW INTO THE REGION...ESPECIALLY ACROSS THE WESTERN
PARTS OF THE AREA. THE INCREASED MOISTURE...DAYTIME HEATING...AND
A WEAK CAP WITH THE HIGH SO FAR OFF SHORE...WILL YIELD A SCENARIO
WHERE AFTERNOON CONVECTION IS EXPECTED. WITH NO ORGANIZED UPPER
LEVEL SUPPORT...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
AT BEST. THE SOUTHWEST FLOW WILL ALSO ALLOW FOR A TREND OF MILDER
TEMPERATURES STARTING ON TUESDAY AFTER A BRIEF COOL DOWN ON
MONDAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 345 PM EDT FRIDAY...
HIGH PRESSURE WILL ADVANCE EAST OFF THE COAST OF NEW ENGLAND ON
TUESDAY...ALLOWING WINDS TO BECOME MORE SOUTHWESTERLY ACROSS THE
MID ATLANTIC...DRAWING DEEPER TROPICAL MOISTURE BACK INTO THE
REGION. AS SUCH...WE CAN EXPECT A RETURN OF AFTERNOON SHOWERS AND
THUNDERSTORMS...WITH INCREASING COVERAGE EACH DAY THROUGH THE
MIDDLE OF THE NEXT WORKWEEK. UPPER LEVEL RIDGING OVER THE CENTRAL
PLAINS WILL BUILD EAST THROUGH THE PERIOD...WHICH WILL RETURN A
MORE SUMMER LIKE FEEL TO THE REGION BY PUSHING TEMPERATURES
SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF SEPTEMBER.
BY THURSDAY NIGHT...A LOW PRESSURE SYSTEM WILL PUSH ACROSS THE
GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. MAY SEE A FEW
STRONG TO SEVERE STORMS DEVELOP AHEAD OF THE FRONT...BUT RIGHT NOW
WILL BE A LITTLE MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN
DUE TO THE ABUNDANT ATMOSPHERIC MOISTURE ACROSS OUR AREA AND LIGHT
UPPER LEVEL WINDS...RESULTING IN POTENTIALLY SLOW MOVING STORMS.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
AS OF 1250 AM EDT SATURDAY...
OVERALL STILL LOOKING AT ISSUES WITH EITHER FOG OR STRATOCU/STRATUS
ACROSS THE AREA LATE TONIGHT. THE LATEST NAM IS AGGRESSIVE SHOWING
REFORMATION OF LOWER CIGS ACROSS MOST OF THE AREA UNDER AN
INVERSION. MEANWHILE THE GFS/CMC ARE CLEARING THINGS OUT ALTHOUGH
THE CMC ACTUALLY SHOWS REDEVELOPMENT WEST OF THE BLUE RIDGE AND
INTO THE ALLEGHANYS DURING THE EARLY MORNING HOURS. THUS HAVE
CONTINUED TO LEAN THE AVIATION FORECAST MORE TOWARD THE CLOUDIER
NAM IN THE WEST AND A BLEND ELSW THROUGH EARLY SAT MORNING.
THUS MEDIUM TO HIGH CONFIDENCE THAT ALL TAF SITES WILL BE GETTING
AT LEAST A BKN CIG OF VFR AT ROA/LYH/DAN BETWEEN 2AM AND 6AM.
MEANWHILE BLF/BCB/LWB WILL BE DEALING WITH AN MVFR CIG FORMING
GIVEN THAT ELEVATIONS ARE HIGHER ALTHOUGH LWB MAY STAY CLEAR
LONGER BEFORE FOG FORMS WITH JUST SOME HIGH CLOUDS AROUND.
POTENTIAL SE UPSLOPE FLOW MAY CAUSE CIG TO DROP UNDER 1KFT AT
TIMES IN THE MORNING ALONG THE BLUE RIDGE SO HAVE A TEMPO GROUP
TO COVER THIS. STILL CANNOT RULE OUT DENSE FOG AT LWB BUT MAY BE
ENOUGH MIXING TO CLEAR THEM OUT FASTER SAT MORNING INTO AN MVFR
CIG...WHILE BCB REMAINS AT THE TOP END OF MVFR. ALL SITES WILL BE
VFR BY LATE MORNING/MIDDAY SAT AS WINDS SHIFT TO THE WEST AND SW.
SURFACE HIGH PRESSURE OVER SOUTHERN NEW ENGLAND WILL DRIFT SOUTH
TO ALONG THE MID ATLANTIC COAST BY SATURDAY EVENING PROVIDING
MAINLY CLEAR SKIES OUTSIDE OF HIGH CLOUDS.
ANOTHER COLD FRONT...ARRIVING FROM THE NW...WILL MOVE INTO THE
AREA LATE IN THE WEEKEND...THEN STALL AND EVENTUALLY WASH OUT JUST
TO OUR SOUTH EARLY NEXT WEEK AS HIGH PRESSURE FROM THE MIDWEST
BUILDS EAST TOWARD THE MID-ATLANTIC. EXPECT A RETURN TO MORE
TYPICAL SUMMERLIKE WEATHER WITH INCREASING CHANCES FOR DIURNALLY-
DRIVEN SHRA/TSRA ON SUNDAY WHEN THE FRONT MOVES SOUTH THROUGH THE
REGION. APPEARS TO BE MOSTLY MVFR CIGS AT WORSE OUTSIDE MORNING
FOG/LOW CLOUDS WHICH WILL LIKELY BE INCREASING AS THE AIR MASS
ACROSS THE REGION BECOMES INCREASINGLY TROPICAL WITH DEWPOINTS IN
THE 60S MOUNTAINS AND NEAR 70 PIEDMONT. AT THIS POINT...NO
WIDESPREAD EXTENDED DURATION OF POOR AVIATION CONDITIONS ARE
EXPECTED.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/WERT
NEAR TERM...JH
SHORT TERM...DS
LONG TERM...NF
AVIATION...JH/PM/WERT/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
238 AM PDT Sat Sep 7 2013
.SYNOPSIS...
The low pressure system responsible for showers and thunderstorms
the last couple of days will bring another round of wet weather to
the Cascades and northern mountains again today. Sunday will be a
drier day for most of the Inland Northwest with showers limited to
mainly the Idaho Panhandle. Dry, summer-like weather will return
Monday through Thursday as a strong high pressure ridge develops
over the region.
&&
.DISCUSSION...
Today through Sunday...A large closed low near Republic will be
nearly stationary today...before moving east towards the North
Idaho Panhandle tonight...and then exiting the area into Montana
on Sunday.
For this morning main focus is the wrap around band near the North
Washington Cascades on the back side of the low where a steady
light rain has been falling around Stehekin. The HRRR has been
consistent with a large area of light rain over far southwest BC
dropping southeast into Mazama, Stehekin early this morning
spreading east into Chelan...Brewster...and the Waterville Plateau
during the mid morning hours. While this rain will be
light...additional rain on saturated ground where mud slides have
already occurred may result in additional slides although
confidence is marginal of this. Given uncertainty will continue
with current Flash Flood Watches for the East Slopes of the
Cascades and Wenatchee area. This wrap around band will swing
northeast towards Colville and Chewelah during the early
afternoon. Cloud cover associated with this may limit thunderstorm
chances this afternoon over the Northeast Washington Mountains and
Idaho Panhandle. West of this band over the Okanogan Highlands,
Okanogan Valley, and East Slopes of the Cascades a better
potential for isolated thunderstorms exists with sun breaks more
likely to develop. Less instability will exist from Spokane
southward due to further proximity from low with only isolated
showers at most expected for today. Cloud cover today will keep
temperatures below average over all of the region.
Tonight showers will decrease with the loss of daytime heating and
be confined mainly to northeast Washington and North Idaho with
the closed low tracking across this region. Then on Sunday showers
will continue in these areas although with the low departing out
of the area showers will only be scattered in nature with a slight
chance of afternoon thunderstorms. A short wave ridge will
approach the Cascades late Sunday afternoon which will allow for
more pronounced warming over Central Washington with less cloud
cover and showers compared to today. JW
Sunday Night: The exiting upper trough may yield some early
evening showers over the Idaho Panhandle, but 500mb temperatures
will be warming and instability profiles don`t suggest more than
isolated thunder potential prior to sunset.
Monday through Friday: Summer will return next week with
temperatures well above average. There is good model agreement
through about Thursday that a high amplitude high pressure ridge
will develop over the Pacific Northwest. Wednesday and Thursday
look to be the warmest days of the week with 850mb temperatures in
the 22-24C range. Many lowland areas will be in the upper 80s to
lower 90s which is about 10 degrees above average.
Forecast confidence diminished markedly Friday into next weekend.
There is very little agreement between the 00z models and run-to-
run consistency has not been good either. A cooling trend into
next weekend is probable, but the timing/track/intensity of an
incoming Pacific trough (and subsequent ridge breakdown) is
highly uncertain at this time. /GKoch
&&
.AVIATION...
06Z TAFS: The pesky and very slow moving low pressure system will
continue to produce scattered precipitation through Saturday night
across the forecast area. While a mid level deck is expected
around the region there should be a break in the precipitation
late tonight...before picking up Saturday afternoon again. At this
time anything below vfr conditions is not expected...although some
fog will be possible early Saturday morning for the KGEG-KCOE
corridor. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 70 54 77 56 81 57 / 20 20 10 10 0 0
Coeur d`Alene 70 54 74 54 81 55 / 20 20 20 10 0 0
Pullman 72 49 75 49 81 49 / 10 10 10 10 0 0
Lewiston 80 57 83 59 87 59 / 10 10 10 0 0 0
Colville 70 50 81 51 85 51 / 70 30 20 10 0 0
Sandpoint 70 49 73 48 78 47 / 50 30 40 20 10 10
Kellogg 71 53 71 54 79 54 / 20 20 40 20 10 10
Moses Lake 74 53 84 55 86 55 / 20 10 0 0 0 0
Wenatchee 73 57 83 60 85 60 / 50 20 0 0 0 0
Omak 74 54 83 56 86 57 / 70 30 10 10 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flash Flood Watch through this evening for East Slopes Northern
Cascades-Wenatchee Area.
&&
$$
AREA FORECAST DISCUSSION...RETRANSMISSION
NWS SAN DIEGO CA
845 AM PDT SAT SEP 7 2013
.SYNOPSIS...
CONTINUED VERY WARM AND HUMID TODAY WITH SCATTERED AFTERNOON
THUNDERSTORMS AGAIN OVER THE MOUNTAINS. THE THUNDERSTORMS WILL
LIKELY PRODUCE TORRENTIAL DOWNPOURS WITH LOCAL FLASH FLOODING
POSSIBLE. LOW PRESSURE WILL BE DEVELOPING ALONG THE WEST COAST EARLY
NEXT WEEK...BRINGING COOLER WEATHER AND DECREASING THUNDERSTORM
CHANCES OVER THE MOUNTAINS AND DESERTS.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SKIES WERE MOSTLY CLEAR EARLY THIS MORNING OVER THE CWA.
HOWEVER...WATER VAPOR IMAGERY INDICATED A SHARP MOISTURE BOUNDARY IN
THE ATMOSPHERE ALONG THE FOOTHILLS. THE 12Z MIRAMAR SOUNDING HAD A
SFC BASED INVERSION WITH LIGHT WINDS UP THROUGH 25K FT. PW HAD
DECREASED TO 1.43 INCHES...BUT GPS SOUNDERS AND SFC DEWPOINT
INCREASES ACROSS THE DESERTS SUPPORT PWS CLOSER TO TWO INCHES. SFC
PRESSURE GRADIENTS AT 14Z ARE WEAK OFFSHORE.
CONTINUED VERY WARM TO HOT AND HUMID AGAIN TODAY. MAIN CONCERN AGAIN
WILL BE THE THUNDERSTORM AND FLASH FLOOD THREAT OVER THE MTNS/
DESERTS. HIGH PW VALUES OVER EASTERN PORTIONS OF THE AREA SUPPORT A
FLASH FLOOD WATCH THIS AFTERNOON AND EVENING. THE 12Z MIRAMAR
SOUNDING LOOKS A BIT MORE STABLE...BUT IT IS IN A DIFFERENT AIRMASS
THAN THE DESERTS. THE LOCAL WRF/HRRR/NAM12 ALL DEVELOP THUNDERSTORMS
OVER THE MTNS THIS AFTERNOON. THE 12Z HRRR ALSO SHOWS ISOLATED
CONVECTION OVER THE INLAND EMPIRE WHICH IS SUPPORTED BY HIGHER SFC
DEWPOINTS AND EASTERLY FLOW THROUGH THE BANNING PASS THIS MORNING.
ANY STORMS THAT DEVELOP OVER THE IE WILL WILL NOT HAVE THE DEEP
LAYER MOISTURE AVAILABLE OVER THE MTNS/DESERTS...SO IT IS NOT
INCLUDED IN THE FLASH FLOOD WATCH.
GLOBAL MODELS GENERALLY AGREE THE LARGE SUBTROPICAL HIGH...CENTERED
OVER THE GREAT PLAINS...WILL DRIFT EASTWARD THROUGH TUE...WHILE A
WEAK TROUGH DEVELOPS SOUTHWARD OVER SOCAL. THIS WILL ALLOW HEIGHTS/
THICKNESS TO DROP OFF ACROSS THE REGION...AND GRADUALLY ALLOW THE
MARINE LAYER TO BECOME REESTABLISHED NEXT WEEK. IN THE MEANTIME...
THE SLOW EASTWARD PROPAGATION OF THE TROUGH AXIS THROUGH THE REGION
SHOULD SHUNT THE DEEP LAYER MONSOONAL MOISTURE OFF TO THE EAST...
DECREASING THE TSTM CHANCES OVER THE MTNS/DESERTS NEXT WEEK.
REMNANTS OF TROPICAL STORM LORENA ARE DRAWN NORTHWARD AHEAD OF THE
TROUGH EARLY NEXT WEEK SO PLACEMENT OF THE DEVELOPING TROUGH AXIS IS
CRITICAL. BOTH THE 00Z ECMWF/06Z GFS SHOW THE AXIS E OF THE CWA ON
MON. THIS SHOULD KEEP THE BULK OF THE CLOUDS AND MOISTURE TO OUR
EAST...HOWEVER THE 00Z ECMWF RUN PULLS IT BACK INTO THE UPPER LOW
CIRCULATION WHICH RESULTS IN CONTINUED PRECIP CHANCES FOR THE ENTIRE
CWA INTO MON. FOR NOW...FAVOR THE GFS MOISTURE FIELD/PCPN...KEEPING
THE THREAT MORE TO THE EAST.
LOOKING AHEAD TO THE END OF NEXT WEEK...00Z/06Z GLOBAL MODEL RUNS
DIVERGE OVER THE SW. BOTH THE GFS/ECMWF LOOK DRY...BUT THE GFS IS
WARMER.
&&
.AVIATION...
071508Z...COAST/VALLEYS...DURING THE 1900-08/0300 UTC
TIME-PERIOD...THUNDERSTORMS OVER MTNS WILL PRODUCE SCT-FEW DEBRIS
CLDS AOA 8000 FT MSL OVER THE COAST/VALLEYS. SLIGHT CHANCE OF FOG
REACHING KSAN...KCRQ...AND/OR KSNA DURING THE 08/1100-1500 UTC
TIME-FRAME...BUT CONFIDENCE IS LOW IN THIS OCCURRING.
OTHERWISE...UNRESTRICTED VIS AND MOSTLY SKC THROUGH SUNDAY MORNING.
MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS DURING THE
1800-08/0100 UTC TIME-PERIOD WITH BASES 7000-10000 FT MSL AND CB
TOPS TO 40000 FT MSL...RESULTING IN LOCAL VIS AOB 2SM IN HEAVY
RAIN...SMALL HAIL...AND POSSIBLE STRONG UP/DOWNDRAFTS.
OTHERWISE...UNRESTRICTED VIS THROUGH SUNDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH FROM 11 AM PDT TODAY THROUGH THIS EVENING FOR
THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE
COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO
COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.
PZ...NONE.
&&
$$
PUBLIC...JAD
AVIATION...HARRISON
AREA FORECAST DISCUSSION
NWS ALBANY NY
1025 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TODAY. THE
SOUTHERLY FLOW AROUND THIS HIGH PRESSURE AREA WILL RESULT IN A
MILDER DAY TODAY. A COLD FRONT WILL CROSS THE REGION LATE TONIGHT
AND EARLY SUNDAY MORNING WITH THE CHANCE FOR SOME RAIN SHOWERS...
FOLLOWED BY BREEZY AND COOLER CONDITIONS BEHIND IT FOR THE REST OF
SUNDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1015 AM EDT...CLOUD SHIELD CONTINUES TO ADVANCE EASTWARD WITH
UPSTREAM REGIONAL RADARS REVEALING THE LEADING EDGE OF THE RAINFALL
ACROSS LAKE ONTARIO. PER EXTRAPOLATION...THE WESTERN DACKS WOULD
SEE HIGHER POPS TOWARD OR SHORTLY AFTER THE NOON HOUR THEN SPREAD
INTO EASTERN NY DURING THE MID AND LATE AFTERNOON. THIS TOO IS IN
AGREEMENT WITH THE RATHER AGGRESSIVE HRRR REFLECTIVITY FORECAST.
PER THESE OBSERVATIONS...HAVE LOWERED AFTERNOON HIGHS A COUPLE OF
DEGREES AND MODIFIED PRECIP/POP POTENTIAL PER EXTRAPOLATION TRENDS.
THE MAIN LIFT AND UPPER SUPPORT ARRIVE AFTER SUNSET WHEN THOSE POPS
INCREASE PER THE PREVIOUS FORECAST.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
THE COLD FRONT WILL CROSS THE REGION WITHIN A FEW HOURS EITHER SIDE
OF SUNRISE ON SUNDAY. AHEAD OF THE FRONT HAVE INCREASED POPS TO
BETWEEN 40 AND 50 PERCENT. DRIER AIR RUSHES IN VERY QUICKLY BEHIND
THE FRONT AND THE FLOW BECOME ANTICYCLONIC BY EARLY AFTERNOON. THIS
WILL MINIMIZE THE CONTINUATION OF ANY SHOWERS IN THE COLD ADVECTION
BEHIND THE FRONT AND HAVE FORECAST THE WEATHER TO BECOME PCPN FREE
ACROSS THE ENTIRE REGION FROM LATE MORNING AND BEHIND. AS ANOTHER
SPRAWLING COOL CANADIAN HIGH PRESSURE SYSTEM WILL BUILDS INTO THE
REGION SUNDAY AFTERNOON AND NIGHT AND THEN MOVES OFFSHORE ON
MONDAY...EXPECT CLEAR TO MAINLY CLEAR SKIES WITH COOL TEMPS SUNDAY
AFTN THROUGH MONDAY.
TEMPERATURE WISE...LOWS SATURDAY NIGHT WILL BE IN THE 50S. HIGHS
SUNDAY WILL RANGE FROM THE UPPER 50S OVER THE ADIRONDACKS WHERE THE
COOLER AIR MOVES IN FIRST...TO THE LOW OR MID 70S FROM THE MID
HUDSON VALLEY TO NORTHWEST CONNECTICUT. LOWS SUNDAY NIGHT WILL BE
IN THE 30S TO LOWER 40S AND PATCHY OR AREAS OF FROST HAS BEEN
FORECAST IN COLDER AREAS AND ALSO BEEN HIGHLIGHTED IN THE HWOALY
PRODUCT. HIGHS MONDAY WILL BE IN THE MID 60S TO MID 70S.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
ONCE AGAIN PRETTY GOOD AGREEMENT AMONGST THE LONGER RANGE MODELS
ALTHOUGH THE CMC ATTEMPTS TO BRING A TROPICAL SYSTEM NEAR OUR REGION
BY NEXT WEEKEND. SINCE THE OTHER MODELS DO NOT HAVE SUCH A
FEATURE...WE HAVE DISCARDED THAT MODEL.
MONDAY NIGHT...IT LOOKS AS A RATHER STRONG WARM FRONT WILL WORK
ACROSS THE REGION MONDAY NIGHT OR EARLY TUESDAY. THE EUROPEAN MODELS
(ECMWF) CONTINUES TO INDICATE A PRETTY GOOD MCS ASSOCIATED WITH THIS
FEATURE...LESS SO BY THE GFS. THE ECMWF STILL INDICATED A 30-40KT
H850 JET THAT COULD TRANSPORT A SLUG OF ELEVATED CONVECTION INTO THE
ADIRONDACKS. FOR NOW...WE HAVE INTRODUCED 30 POPS ACROSS OUR
NORTHWESTERN ZONES WHERE IT APPEARS THAT GREATEST QPF COULD TAKE
PLACE...SLIGHT POPS ELSEWHERE. OVERNIGHT LOWS LOOK TO BE IN THE 50S
FROM ALBANY SOUTHWARD...40S NORTH.
BY TUESDAY RISING HEIGHTS AND A SOUTHWESTERLY FLOW LOOKS TO USHER IN
SOME MUCH WARMER AND HUMID AIR. DEPENDING ON HOW HOW FAST THE CLOUDS
LIFT OUT WILL ULTIMATELY DETERMINE HOW WARM WE GET. H850
TEMPERATURES LOOK TO JUMP WELL INTO THE TEENS. WE FIGURE THE CLOUDS
WILL BE SOMEWHAT SLOW TO BURN OFF SO WENT ON THE LOWER END OF
MIXING...HIGHS 75 TO 80. WE CARRY ONLY SLIGHT CHANCES OF SHOWERS
THROUGH WEDNESDAY MORNING. TUESDAY NIGHT LOOKS RATHER MUGGY BY
SEPTEMBER STANDARDS WITH LOWS GENERALLY IN THE 60S.
WEDNESDAY LOOKS UNSEASONABLY WARM. H850 TEMPERATURES LOOK TO CREST
NEAR +18C VIA THE 00Z GFS/+20C ON THE ECMWF! WE WENT ON THE HIGH
SIDE OF GUIDANCE WITH HIGHS WELL INTO THE 80S...PUSHING NEAR 90
DEGREES IN THE MID HUDSON VALLEY. DEWPOINTS LOOK TO RISE WELL INTO
THE 60S TO NEAR 70 GIVING THOSE AIR CONDITIONER AT LEAST ONE MORE
WORKOUT FOR THE YEAR.
BY LATE WEDNESDAY...THE AIR LOOKS TO BECOME QUITE UNSTABLE AS THE
FIRST IN A SERIES OF COLD FRONTS (OR PRE-FRONTAL TROUGH) NEARS OUR
REGION. WILL CARRY 30/40 POPS LATE AFTERNOON INTO WEDNESDAY NIGHT.
LOWS WEDNESDAY WILL REMAIN WARM...60S TO NEAR 70.
THURSDAY...IT LOOKS AS NOT ONE BUT TWO FRONTS WILL PASS
THROUGH...LINGERING INTO THE EVENING. WHILE IT WILL LIKELY NOT BE
SHOWERING OR STORMING THE ENTIRE TIME...AT THIS POINT...IT IS HARD
TO TIME WHEN AND IF CONVECTION WOULD OCCUR...BUT THE THREAT
CERTAINLY LOOKS THERE...WITH THE GFS INDICATE SURFACE BASED CAPES
WELL OVER 1000 JOULES. WILL CARRY 30/40 POPS THROUGH THIS PERIOD.
BOTH THE GFS AND ECMWF BOTH INDICATE THE MAJOR COLD FRONT WILL SWEEP
THROUGH THE REGION THURSDAY NIGHT WITH PERHAPS A LINGERING SHOWER OR
TWO. FRIDAY...ANOTHER MUCH COOLER CANADIAN AIRMASS LOOKS TO INVADE.
WILL HAVE SLIGHT POPS ACROSS OUR HIGHER TERRAIN WHERE UPSLOPE AND
LINGERING COLD AIR ADVECTION PROCESSES COULD TRIGGER AN INSTABILITY
SHOWER WHILE VALLEY AREAS LOOK DRY. IT WILL BE QUITE BREEZY. HIGHS
WILL RANGE FROM ABOUT 70 IN THE HUDSON VALLEY...TO ONLY 60S
ELSEWHERE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
KPSF WENT BRIEFLY TO IFR EARLIER THIS MORNING. WHILE KALB DID
NOT...WE HAD IFR CLOUDS AND SOME IFR FOG AT OUR OFFICE THAT WERE
LIKELY BELOW 1000 FEET. FOR NOW WE DECIDED NOT TO INCLUDE THE 200
FOOT BROKEN CEILING AT KALB AND 2SM BR IN A ONE HOUR TEMPO THROUGH
12Z.
ANY AND ALL FOG WILL BURN OFF BY AROUND 13Z....LEAVING US WITH A
VFR DAY. HIGH CLOUDS WILL GENERALLY INCREASE AND SO WILL A SOUTHERLY
BREEZE....TO THE TUNE AROUND 10KTS AT KALB.
ANY AND ALL FOG WILL DISSIPATE BY AROUND 14Z. VFR CONDITIONS WILL
PREVAIL DURING THE DAY SATURDAY WITH A GENERAL INCREASE IN HIGH
CLOUDS AND A SOUTHERLY BREEZE...APPROACHING 10KTS BY MIDDAY.
BY LATE IN THE DAY...A FEW SHOWERS...AHEAD OF THE NEXT COLD FRONT
COULD IMPACT THE TERMINALS PERHAPS A BRIEF REDUCTION IN VISIBILITY
AND LOWERING OF CIGS. FOR NOW...CONTINUED WITH VCSH BY LATE IN THE
AFTERNOON...EXCEPT NOT UNTIL EVENING AT KPOU.
OUTLOOK...
SUNDAY...LOW OPERATIONAL IMPACT. BREEZY.
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF
SHRA...TSRA. TUESDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF
SHRA...TSRA. TUESDAY NIGHT: MODERATE OPERATIONAL IMPACT. SLIGHT
CHANCE OF SHRA...TSRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT.
CHANCE OF SHRA...TSRA. WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT.
CHANCE OF SHRA...TSRA.
&&
.FIRE WEATHER...
NO FIRE WEATHER ARE ANTICIPATED OVER THE NEXT SEVERAL DAYS.
RH VALUES WILL DROP TO BETWEEN 35 AND 50 PERCENT THIS AFTERNOON
WITH SOUTH TO SOUTHWEST WINDS AROUND 5 TO 10 MPH. RH VALUES WILL
ONCE AGAIN RETURN TO NEAR 100 PERCENT TONIGHT WITH A GOOD CHANCE OF
RAIN SHOWERS.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS ARE ANTICIPATED THROUGH TUESDAY. RIVER LEVELS
WILL CONTINUE TO RECEDE OR HOLD STEADY OVER THE NEXT FEW DAYS.
HIGH PRESSURE WILL MOVE OFF THE EASTERN SEABOARD TODAY. A COLD FRONT
WILL CROSS THE REGION LATE TONIGHT AND EARLY SUNDAY MORNING WITH THE
CHANCE FOR SOME RAIN SHOWERS...FOLLOWED BY BREEZY AND COOLER
CONDITIONS BEHIND IT FOR THE REST OF SUNDAY. AS ANOTHER LARGE HIGH
PRESSURE SYSTEM SETTLES OVER THE REGION...THERE WILL BE DRY WEATHER
THROUGH TUESDAY.
THE QPF OVER THE WEEKEND WILL BE FAIRLY LIGHT. MOST AREAS OUTSIDE
THE ADIRONDACKS WILL ONLY SEE A TENTH OR TWO OF AN INCH AT
MOST...WITH UP TO A THIRD OF AN INCH ACROSS THE ADIRONDACKS. THIS
RAINFALL WILL HAVE LITTLE IMPACT ON AREA RIVERS AND STREAMS.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM/BGM
SHORT TERM...GJM
LONG TERM...HWJIV
AVIATION...HWJIV
FIRE WEATHER...GJM
HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS POCATELLO ID
906 AM MDT SAT SEP 7 2013
.UPDATE...STRONG MOISTURE GRADIENT LAYING ACROSS EAST IDAHO TODAY
AS UPPER LOW CONTINUES TO DRIFT EAST ALONG THE PACNW/CANADIAN
BORDER. DEEPEST MOISTURE IN PLACE OVER THE EASTERN HALF OF THE
FORECAST AREA MAINLY SNAKE PLAIN AND HIGHLANDS SOUTH/EAST. CENTRAL
MOUNTAINS MUCH DRIER BUT CLOSER TO BEST DYNAMICS ASSOCIATED WITH
UPPER LOW. HRRR THIS MORNING PAINTING WIDE SWATH OF MOISTURE
MOVING THROUGH THE SOUTH/EAST HIGHLANDS LATE THIS MORNING INTO
EARLY THIS AFTERNOON. NAM/LOCAL WRF DEVELOPS BETTER SWATH OF
CONVECTION LATER THIS AFTERNOON. CLOUD COVER EARLY THIS MORNING
MAY ALSO HAVE A SMALL IMPACT ON INSTABILITY. HAVE MADE A FEW
TWEAKS TO SKY/POP/WX GRIDS FOR TODAY...HOLDING ON TO HIGH CHANCE
POPS IN THE DEEPEST MOISTURE BUT RETAINING ISOLATED POPS OVER
PORTIONS OF THE CENTRAL MOUNTAINS. DMH
&&
.PREV DISCUSSION... /ISSUED 319 AM MDT SAT SEP 7 2013/
SHORT TERM...TODAY THROUGH MONDAY.
UPPER LOW IN WASHINGTON STATE WILL CONTINUE TO PUSH VERY SLOWLY
EAST THROUGH MONDAY. MONSOONAL MOISTURE CONTINUES TO BE OVER THE
REGION ON THE SOUTHWESTERLY FLOW ALOFT AND EXPECT CONTINUED
ISOLATED TO SCATTERED THUNDERSTORMS TODAY WITH THE BEST ACTIVITY
AGAIN IN THE EASTERN AREAS. UPPER TROF FINALLY MOVES THROUGH
SUNDAY AND ENOUGH DYNAMICS AND INSTABILITY TO CONTINUE WITH THE
THREAT FOR THUNDERSTORMS BUT NOT AS WIDESPREAD AS TODAY. FLOW
ALOFT TURNS NORTHWESTERLY MONDAY AND EXPECT DRY CONDITIONS ACROSS
THE WHOLE REGION FINALLY. TEMPERATURES MONDAY SHOULD ALSO BE NEAR
SEASONAL NORMALS AFTER THE EXTENDED PERIOD OF WELL ABOVE NORMAL
CONDITIONS. EXPECT SOME BREEZY CONDITIONS SUNDAY WITH THE PASSAGE
OF THE UPPER TROF AND SURFACE COLD FRONT.
GK
LONG TERM...TUESDAY THROUGH SATURDAY.
UPPER RIDGE BUILDS IN TUESDAY AND EXPECT DRY CONDITIONS TUESDAY
AND WEDNESDAY. FLOW AGAIN TURNS SOUTHERLY ALLOWING MOISTURE BACK
INTO THE REGION AND HAVE A CHANCE OF SHOWERS AND THUNDERSTORMS
THURSDAY THROUGH SATURDAY.
GK
AVIATION...THE LATEST SATELLITE IMAGERY WAS SHOWING A LOW PRESSURE
SYSTEM LIFTING NORTH INTO SRN BRITISH COLUMBIA AS SUB-TROPICAL
MOISTURE CONTINUED TO ARC NORTH ACROSS SE IDAHO AND DRIER CONDITIONS
OVERSPREAD THE SW. MODEL SOLUTIONS SHOW THE UPPER LOW SHIFTING EAST
ALONG THE CANADIAN BORDER TODAY AND SUNDAY EFFECTIVELY SHUNTING THE
SUB-TROPICAL FLOW FURTHER EAST INTO WYOMING SUNDAY. MAY STILL HAVE
TO CONTEND WITH VCTS/TSRA REMARKS IN THE TERMINALS TODAY AND TO A
LESSER EXTENT SUNDAY AS THE SUB-TROPICAL MOISTURE IS PUSHED FURTHER
EAST...OTHERWISE VFR CONDITIONS SHOULD PREVAIL. HUSTON
FIRE WEATHER...A LOW PRESSURE SYSTEM POSITIONED ALONG THE
WASHINGTON/BRITISH COLUMBIA BORDER EARLY THIS MORNING WILL BEGIN TO
MIGRATE EAST TODAY AND SUNDAY. SUB-TROPICAL MOISTURE STREAMING NORTH
ACROSS THE GREAT BASIN WILL GET SHUNTED FURTHER EAST INTO WYOMING
SUNDAY AND COLORADO BY MONDAY AS A FAIRLY DRY NW FLOW OVERSPREADS
IDAHO IN THE WAKE OF THE EXITING LOW. WIND GUSTS WILL NOSE UP TOWARD
WARNING LEVELS SUNDAY AFTERNOON WHILE MINIMUM HUMIDITY LEVELS FALL
INTO THE UPPER TEENS ACROSS THE CNTRL MOUNTAINS AND ARCO DESERT
REGIONS. FUELS STILL FAIRLY MOIST DUE TO RECENT MONSOONAL ACTIVITY
THUS NO HIGHLIGHTS ARE WARRANTED AT THIS TIME. A RIDGE OF HIGH
PRESSURE AND WARMER TEMPERATURES BUILD ACROSS THE REGION THROUGH
MID-WEEK AS A SUB-TROPICAL DISTURBANCE LIFTS NORTH THROUGH
MEXICO/ARIZONA. THE ADVANCING SUB-TROPICAL MOISTURE WILL LIKELY LIFT
INTO SRN IDAHO THURSDAY/FRIDAY FOR YET ANOTHER ROUND OF HEAVY
SHOWERS AND THUNDERSTORMS. HUSTON
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
720 AM CDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 709 AM CDT SAT SEP 7 2013
FORCING IN THE 600-500MB LAYER IS CAUSING THE LINE OF SPRINKLES/LIGHT
SHOWERS AND THE ONE OR TWO THUNDERSTORMS ACROSS THE CWFA. WHERE
RAIN IS REACHING THE GROUND IT IS MAINLY A TRACE OR A FEW
HUNDREDTHS.
PER THE RAP TRENDS...THIS FEATURE WILL CLEAR THE CWFA BY MID
MORNING. ANOTHER AREA OF FORCING ARRIVES ALMOST IMMEDIATELY BEHIND
THE DEPARTING LINE. THUS ISOLATED TO SCATTERED SPRINKLES/LIGHT
SHOWERS CAN BE EXPECTED FOR THE MORNING.
DAYTIME HEATING WITH THE SECOND AND THEN THIRD ROUND OF FORCING
ALOFT IS EXPECTED TO INITIATE ISOLATED TO LOW END SCATTERED
SHOWERS AND SOME THUNDERSTORMS DURING THE AFTERNOON AND INTO THE
EVENING HOURS. ..08..
&&
.SYNOPSIS...
ISSUED AT 324 AM CDT SAT SEP 7 2013
06Z SFC ANALYSIS HAS WEAK LOWS AT KANW AND KSTC WITH WEAK
BOUNDARIES/FRONTS FROM THE NE/SD BORDER INTO MINNESOTA AND
WISCONSIN. DEW POINTS WERE MAINLY IN THE 60S ACROSS THE MIDWEST WITH
50S OVER THE EASTERN GREAT LAKES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT SEP 7 2013
RADAR TRENDS SHOW SHOWERS AND A FEW STORMS FROM EASTERN WISCONSIN
BACK THROUGH KAUW. SOME SPRINKLES WERE OCCURRING ACROSS CENTRAL IOWA.
SATELLITE AND MODELS SHOW A VERY WEAK SHORTWAVE MOVING FROM
MINNESOTA THROUGH WISCONSIN DURING THE DAY WHILE AN EVEN WEAKER ONE
PASSES TO THE SOUTH/WEST OF THE CWFA. AT BEST A FEW SPRINKLES MAY
OCCUR THIS MORNING ACROSS THE NORTHEAST CWFA.
THIS AFTERNOON...THE SITUATION IS MORE UNCERTAIN. WARM TEMPERATURES
ALOFT MAY PRECLUDE ANY DIURNAL CONVECTION FROM OCCURRING. HAVE OPTED
TO MAINTAIN THE SCHC POPS IN THE NORTHEAST CWFA FROM LATE AFTERNOON
ON. IF CONVECTION OCCURS...OVERALL COVERAGE MAY BE 5 PERCENT AT BEST.
MOISTURE POOLING NEAR THE FRONT/BOUNDARY SHOULD RESULT IN MID AND
UPPER 60 DEW POINTS ACROSS THE AREA. THIS MOISTURE COMBINED WITH
TEMPERATURES IN THE UPPER 80S TO MID 90S MAY PUSH HEAT INDEX VALUES
CLOSE TO 100 IN THE SOUTHWEST/WEST CWFA DURING THE AFTERNOON.
TONIGHT...THE OVERALL FORCING IS QUITE WEAK AND CONFINED RIGHT
AROUND THE FRONT/BOUNDARY AND BEHIND IT. THUS WILL MAINTAIN THE SCHC
POPS FOR TONIGHT BUT THE OVERALL SITUATION SUGGESTS A MAJORITY OF
THE AREA WILL REMAIN DRY TONIGHT. ..08..
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT SEP 7 2013
IN THE NEAR TERM THE MAIN CONCERN WITH BE RAIN CHANCES SUNDAY
ASSOCIATED WITH A STALLED FRONTAL BOUNDARY OVER NORTHERN MO. THE
SHORT RANGE MODELS SHOW THE SURFACE BOUNDARY JUST SOUTH OF THE
FORECAST AREA SUNDAY MORNING...BUT KEEP THE H8 BOUNDARY OVER THE
SOUTHERN CWFA. WITH WEAK CONVERGENCE NEAR THE H8 BOUNDARY AND
SURFACE BASED CAPES AROUND 2K J/KG A FEW STORMS ARE POSSIBLE. WEAK
FORCING AND WARM MID LEVEL TEMPS SHOULD KEEP COVERAGE OF SHRA/TSRA
ISOLATED SO KEPT POPS IN THE SLIGHT CHANCE RANGE.
THE LATE SUMMER/EARLY FALL HEAT WILL RETURN TO THE AREA MONDAY AS
THE SURFACE BOUNDARY LIFTS NORTH IN RESPONSE TO LOW PRESSURE MOVING
THROUGH THE NORTHERN PLAINS. AT THIS TIME IT APPEARS THE WARM FRONT
WILL NOT REACH THE NORTHERN CWFA UNTIL LATE AFTERNOON MAKING IT
UNLIKELY THAT THE 90 DEGREE TEMPERATURES WILL REACH NORTHWEST
IL...BUT THE REST OF THE AREA SHOULD SEE HIGHS IN THE LOW TO MID 90S.
SOUTHWEST WINDS SHOULD CONTINUE THROUGH THE NIGHT KEEPING TUESDAYS
LOWS NEAR 70. THE HOT WEATHER WILL CONTINUE TUESDAY AS A COLD
FRONT MOVES THROUGH NORTHWEST IA. GUSTY SOUTHWEST WINDS AHEAD OF
THE FRONT AND PLENTY OF SUN SHOULD HELP THE LOW LEVELS MIX TO AT
LEAST H8 YIELDING LOW TO MID 90S AGAIN FOR HIGHS. THE NORTHWEST MAY
BE THE EXCEPTION WITH CLOUDS EXPECTED TO INCREASE DURING THE
AFTERNOON SUPPRESSING THE HEATING SOME. A LOW THREAT OF SHRA/TSRA
WAS MENTIONED IN THE NORTH...SINCE THE FRONT WILL BE NEARBY 00Z.
TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT WILL DROP SOUTH THROUGH
THE FORECAST AREA...BRINGING WITH IT THE BEST CHANCE OF RAIN MOST OF
THE AREA HAS HAD IN RECENT WEEKS. POPS STILL WERE KEPT IN THE HIGH
CHANCE CATEGORY MAINLY BECAUSE UPPER FLOW LOOKS CONVERGENT TUESDAY
NIGHT WHICH COULD HAMPER THE DEVELOPMENT OF SHRA/TSRA. CHANCE
POPS WERE CONTINUED OVER MOST OF THE AREA WEDNESDAY THEN TAPERED
BACK TO SLIGHT CHANCE FOR WEDNESDAY NIGHT AS THE FRONT MOVES SOUTH
OF THE FORECAST AREA. COOLER TEMPERATURES WILL SPREAD OVER THE AREA
FOR THE END OF THE WEEK. IMMEDIATELY BEHIND THE COLD FRONT HIGHS
WEDNESDAY WILL BE IN THE 80S. BY FRIDAY HIGHS IN THE 70S ARE
EXPECTED. OVERNIGHT LOWS SHOULD COOL INTO THE 50S BY FRIDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 709 AM CDT SAT SEP 7 2013
MAINLY VFR WX WILL BE SEEN THROUGH 00Z/08. A WEAK DISTURBANCE
MOVING THROUGH IOWA/ILLINOIS WILL KEEP VCSH AT KMLI/KBRL THROUGH
15Z/07. DIURNAL SHRA/TSRA WILL BE POSSIBLE AFT 18Z/07 AND IF A
TSRA IMPACTS A TAF SITE...A BRIEF PERIOD OF MVFR WX WILL BE
POSSIBLE. A FRONT WILL MOVE THROUGH IOWA/ILLINOIS AFT 00Z/08
SHIFTING WINDS AROUND TO THE NORTHEAST. MVFR VSBYS MAY BE POSSIBLE
AFT 03Z/08 DUE TO HIGH MOISTURE LEVELS IN THE LOWER ATMOSPHERE.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...08
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1058 AM EDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1057 AM EDT SAT SEP 7 2013
TRICKY FORECAST FOR THE REST OF TODAY...AS THE COLD FRONT CONTINUES
TO SLIDE SOUTH ACROSS THE SOUTHEAST PART OF UPPER MICHIGAN. THE
THUNDERSTORMS ASSOCIATED WITH THIS FRONT HAVE NEARLY LEFT CWA IN
LAKE MICHIGAN. OTHER THAN A FEW SHOWERS REDEVELOPING OVER
DICKINSON/MENOMINEE COUNTIES THIS AFTERNOON...THE SHOWERS
ASSOCIATED WITH THE FRONT SHOULD BE DONE.
ATTENTION THEN TURNS TO THE CLOUDINESS OVER LAKE SUPERIOR. VISIBLE
SATELLITE SHOWS TWO CLOUD DECKS...WITH MID CLOUDS SHIFTING
EAST-SOUTHEAST AND A LOW STRATUS DECK DROPPING SOUTH TO
SOUTH-SOUTHWEST. THERE WAS SOME UNCERTAINTY ON IF THE CLOUDS WERE
FOG OR LOW STRATUS...AS WEBCAMS ALONG LAKE SUPERIOR IN THE KEWEENAW
AND EAST WEREN/T POINTING ONE WAY OR ANOTHER. BUT THE 1435Z OB FROM
KCMX HAS INDICATED IT IS MORE OF A LOW STRATUS WITH SOME FOG OR
DRIZZLE. THUS...WILL ADJUST THE FORECAST FOR LOCATIONS NEAR LAKE
SUPERIOR FOR MORE CLOUDINESS THIS AFTERNOON UNDER THE
NORTH-NORTHEAST WINDS. BASED OFF THE THICKNESS OF THE LOW CLOUDS ON
THE LATEST RAP RUNS...WILL ADD A MENTION OF DRIZZLE TO THE HIGHER
TERRAIN OF NORTH CENTRAL AND THE KEWEENAW DURING THE AFTERNOON.
THIS COOL FLOW OFF LAKE SUPERIOR WILL ALSO LEAD TO TEMPERATURES
FALLING THROUGH THE AFTERNOON FROM THE CURRENT VALUES IN THE LOWER
70S AND INTO THE MID-LOWER 60S TOWARDS EVENING. UPDATED GRIDS WILL
BE OUT SHORTLY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 519 AM EDT SAT SEP 7 2013
GENERALLY DECAYING SHOWERS AND THUNDERSTORMS HAVE BEEN THE
RULE...AND DESPITE ALL THE MOISTURE AROUND FOG HAS BEEN SLOW TO
MATERIALIZE ANYWHERE THAT HAD LESS THAN 0.25IN OF RAIN OVER THE PAST
24 HOURS. FOG OVER W AND E LAKE SUPERIOR TO PUSH S BEHIND THE COLD
FRONT SET UP FROM NW WI THROUGH THE KEWEENAW AND NE LAKE SUPERIOR.
THIS BOUNDARY WILL BE ENOUGH TO SPARK THE POTENTIAL OF ADDITIONAL
SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI LATE
THIS MORNING AND EARLY THIS AFTERNOON...BEFORE SIGNIFICANTLY
COOLER/DRIER AIR WORKS IN. MODEL TIMING ON THE COLD FRONT IS
REASONABLE...SLIPPING TO FAR S CENTRAL PORTIONS OF THE CWA BY 18Z.
EXPECT SLOWLY FALLING TEMPS THIS AFTERNOON OVER THE N AS A
RESULT...AS CLOUD COVER BEGINS TO DIMINISH. KEPT WITH THE COOL TEMPS
TONIGHT ON NNE FLOW AND 850MB TEMPS FALLING TO A CWA AVG 9C. PW
VALUES SHOULD FALL FROM AROUND 150 PERCENT OF NORMAL /1.5IN/ THIS
MORNING TO A 40-50 PERCENT OF NORMAL BY 12Z SUNDAY /0.35-0.4IN/.
LOWERED THE TRADITIONAL COOL SPOTS A BIT MORE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 505 AM EDT SAT SEP 7 2013
IN THE LONG TERM...PATTERN IN THE MEAN WILL CONTINUE TO FEATURE A NW
CANADA RIDGE AND ERN N AMERICA TROF. THIS WILL RESULT IN SHORTWAVES
PERIODICALLY DROPPING SE FROM THE NW RIDGE INTO THE ERN TROF. TWO
MORE SIGNIFICANT WAVES WILL BRING NOTABLE AMPLIFICATION OF THE ERN
TROF. THE FIRST WILL BE THIS WEEKEND AND THE SECOND WILL BE LATE IN
THE UPCOMING WEEK. THE SECOND AMPLIFICATION LOOKS LIKE IT WILL BRING
THE COOLEST AIR TO THE UPPER LAKES...POSSIBLY POSING A RISK OF THE
FIRST WIDESPREAD FROST OF THE SEASON LATE WEEK. BTWN THE 2 SURGES OF
COOL AIR...TEMPS WILL BE AT OR ABOVE NORMAL. UNDERNEATH THE LARGER
SCALE RIDGE/TROF PATTERN...MID LEVEL LOW CURRENTLY OVER ERN WA WILL
OPEN UP AND SHIFT GENERALLY E ROUGHLY ALONG THE U.S./CANADA
BORDER...AFFECTING THE UPPER LAKES MON/TUE. THIS SYSTEM SHOULD BRING
THE BEST CHANCE OF PCPN DURING THE LONG TERM PORTION OF THE FCST.
FARTHER DOWN THE ROAD...GUIDANCE SUGGESTS THE NW CANADA RIDGE WILL
BE REPLACED BY A TROF...RESULTING IN DOWNSTREAM HEIGHT RISES ACROSS
THE CNTRL CONUS. SO...A WARM PERIOD MAY BE SHAPING UP BEYOND THIS 7
DAY FCST.
BEGINNING SUN...ON THE BACKSIDE OF THE AMPLIFYING ERN TROF...
CANADIAN HIGH PRES WILL SETTLE SE OVER THE UPPER GREAT LAKES. ONLY
FCST CONCERN CONTINUES TO BE THE POTENTIAL FOR SOME MORNING LOW
CLOUDS OFF LAKE SUPERIOR IN UPSLOPE N/NE FLOW. THE NAM IS COOLEST IN
BRINGING 850-875MB TEMPS DOWN TO AROUND 5C ACROSS LAKE SUPERIOR AT
12Z SUN. OTHER GUIDANCE IS AROUND 2C WARMER. IF THE COOLER NAM IS
CORRECT...WATER TEMPS AS HIGH AS 16-18C OVER SRN LAKE SUPERIOR WILL
BE SUFFICIENT FOR STRATOCU OFF THE LAKE. SINCE LOW CLOUDS ARE
EVIDENT OVER HUDSON BAY INTO ADJACENT NRN MANITOBA/NRN ONTARIO AND
SINCE WIND FLOW AHEAD OF HIGH MAY TEND TO ADVECT SOME OF THIS
SHALLOW MOISTURE INTO THE AREA...OPTED TO RETAIN SOME CLOUD COVER
SUN MORNING NEAR LAKE SUPERIOR EVEN IN FAVORING GUIDANCE WARMER THAN
THE NAM. UPSLOPE CLOUDS SHOULDN`T STICK AROUND LONG UNDER
INCREASINGLY ANTICYCLONIC LOW-LEVEL FLOW...ADVECTION OF DRIER AIR
AND DAYTIME HEATING. FARTHER INLAND...MAY SEE A BLOSSOM OF SCT TO
PERHAPS BKN CU/STRATOCU FOR JUST A BRIEF TIME BEFORE DAYTIME HEATING
MIXES OUT LOW-LEVEL MOISTURE. THE AFTN HRS SHOULD FEATURE ABUNDANT
SUNSHINE ACROSS THE BOARD. TEMPS WILL BE ON THE COOL SIDE OF NORMAL
DESPITE THE SUNSHINE. MIXING TO THE INVERSION BASE ON FCST SOUNDINGS
YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING INFLUENCE OF THE
GREAT LAKES.
SUN NIGHT...MIDLEVEL LOW CURRENTLY OVER ERN WA WILL HAVE OPENED UP
AND WILL REACH SRN SASKATCHEWAN/ERN MT BY 12Z MON. IN RESPONSE...
DEVELOPING LOW-LEVEL JET WILL SHIFT ACROSS THE DAKOTAS INTO MN
DURING THE NIGHT. THE ECMWF CONTINUES TO BE THE FASTEST SPREADING
PCPN INTO UPPER MI SUN NIGHT IN ASSOCIATION WITH A LEAD MINOR
SHORTWAVE MOVING INTO THE UPPER LAKES. THE UKMET HAS NOW FOLLOWED
SUIT. THE GFS HAS PCPN REACHING THE FAR W OVERNIGHT. MEANWHILE...THE
NAM/GEM MAINTAIN STRONGER SFC HIGH PRES RIDGING BACK INTO THE UPPER
LAKES AND THUS KEEP PCPN W OF UPPER MI THRU 12Z MON. FOR NOW...PLAN
TO MAINTAIN CONTINUITY WITH THE LAST FEW FCST CYCLES AND WILL ONLY
BRING SCHC POPS INTO THE FAR W OVERNIGHT...SIMILAR TO THE GFS WHICH
REPRESENTS A GOOD COMPROMISE BTWN THE ECMWF/UKMET AND GEM/NAM.
OTHERWISE...SOUTHERLY RETURN FLOW OF WARMER/MOISTER AIR AND AN
INCREASE IN CLOUDS WILL RESULT IN A WARMER NIGHT MOST AREAS...
ESPECIALLY OVER THE W WHERE GRADIENT WILL BE TIGHTENING FIRST AND
WHERE CLOUDS WILL ARRIVE EARLIEST. LINGERING DRY AIR MASS IN THE
EVENING COMBINED WITH INITIALLY CLEAR SKIES AND LIGHT/CALM WIND OVER
THE E MAY ALLOW TEMPS AT TRADITIONAL INTERIOR COLD SPOTS TO FALL
INTO THE LWR 40S.
MON/TUE...MAIN SHORTWAVE WILL CONTINUE TO TRACK E...PASSING ACROSS
THE UPPER LAKES MON NIGHT/TUE. WHILE TIMING OF FEATURE HAS
IMPROVED...TRACK OF ASSOCIATED SFC LOW REMAINS MORE UNCERTAIN.
THE ECMWF HAS TRENDED S AND HAS SFC LOW TRACKING ACROSS UPPER MI...
NOT TOO DIFFERENT FROM THE NAM. ONLY SCNTRL AND ERN UPPER MI MAY
SLIP INTO THE WARM SECTOR MON NIGHT. END RESULT WOULD PROBABLY BE
FAIRLY WIDESPREAD SHRA/TSRA ACTIVITY ACROSS THE FCST AREA MON...
ESPECIALLY NRN PORTIONS. THE GFS/GEM ARE FARTHER N (GEM HAS BEEN ALL
ALONG) AND HAVE SFC LOW TRACKING OVER OR JUST N OF LAKE SUPERIOR.
RESULT WOULD BE SHRA/TSRA ACTIVITY N OF WARM FRONT BEING SHIFTED
FARTHER N...PERHAPS MOSTLY N OF UPPER MI MON/MON NIGHT. WITH THE
ECMWF NORMALLY PROVIDING BETTER GUIDANCE AND WITH 2 CONSECUTIVE RUNS
NOW SHOWING THE FARTHER S TRACK...HEDGED FCST SLIGHTLY IN THAT
DIRECTION WHICH RESULTED IN INCREASING POPS/QPF A BIT ACROSS THE N
MON/MON NIGHT. EFFECTIVE SHEAR MON LOOKS BE ON THE ORDER OF
30-40KT...SUPPORTING THE POTENTIAL OF STRONG TO SVR STORMS...BUT
MUCH WILL DEPEND ON THE MAGNITUDE OF INFLOW INSTABILITY FOR THE
ELEVATED STORMS. EVEN THE GFS WITH ITS FARTHER N SFC LOW TRACK IS
SLOW TO BRING SUFFICIENT INSTABILITY N FOR STRONG/SVR STORMS MON.
BETTER POTENTIAL OF SVR STORMS SHOULD BE MON NIGHT AS INSTABILITY
AXIS SHIFTS INTO THE UPPER LAKES. HOWEVER...IF WARM FRONT LIFTS N OF
THE AREA...EXPECTED ARRIVAL OF COLD FRONT LATE NIGHT INTO TUE
MORNING WOULD BE MORE IN SYNC WITH DIURNAL MIN...SUGGESTING A
DIMINISHED SVR THREAT. IF WARM FRONT ONLY LIFTS INTO UPPER MI...THEN
THERE WOULD BE THE POTENTIAL FOR ELEVATED SVR STORMS N OF FRONT MON
NIGHT. AT LEAST WITH SHORTWAVE RAPIDLY WEAKENING AS IT MOVES ACROSS
THE UPPER LAKES...THERE DOES NOT APPEAR TO BE A POTENTIAL FOR
WIDESPREAD SVR STORMS. LATEST SPC OUTLOOK ONLY HAS PORTIONS OF UPPER
MI IN A 5 PCT RISK WHICH APPEARS REASONABLE AT THIS TIME. ON TUE...
SHRA/TSRA CHANCES SHOULD BE MOSTLY CONFINED TO THE ERN FCST AREA AS
SFC LOW/COLD FRONT WILL STILL NEED TO PASS THRU THAT AREA.
HEADING INTO WED/THU...THE ECMWF HAS CONTINUED TO BACK OFF ON ITS
FARTHER W AND MUCH MORE SHARPLY DIGGING SHORTWAVE INTO THE UPPER
MISSISSIPPI VALLEY AND GREAT LAKES. NOW...MEDIUM RANGE GUIDANCE IS
GENERALLY WELL CLUSTERED WITH THE TROF AMPLIFICATION OCCURRING THRU
THE GREAT LAKES AND THEN INTO NEW ENGLAND LATE WEEK. WITH MUCH OF
THE DEEP MOISTURE SWEPT OUT OF THE AREA BY THE PRIOR SHORTWAVE...
NOTHING MORE THAN LOW CHC POPS APPEAR WARRANTED WED AS COLD FRONT
DROPS THRU THE UPPER LAKES. SHRA CHANCES MAY LINGER THRU THU WITH
HINTS OF ANOTHER WAVE DROPPING ACROSS THE AREA INTO THE AMPLIFYING
TROF. THU WILL FEEL LIKE AUTUMN AS COOL AIR MASS DUMPS INTO THE
UPPER LAKES ON BREEZY NW WINDS. IT`S POSSIBLE MAX TEMPS MAY ONLY BE
IN THE 50S OVER MUCH OF THE FCST AREA THU IF ANOTHER SHORTWAVE DOES
DROP INTO THE UPPER LAKES...RESULTING IN MOSTLY CLOUDY SKIES AND SCT
SHRA. IT APPEARS SFC HIGH WILL SETTLE INTO THE AREA THU NIGHT PER
CONSENSUS OF MEDIUM RANGE GUIDANCE. IF SO AND IF STRATOCU CLEARS
OUT...THERE WILL BE A WIDESPREAD FROST IN THE INTERIOR...ESPECIALLY
OVER THE W WHICH WILL BE CLOSER TO ARRIVING SFC HIGH PRES CENTER.
WITH SFC HIGH PRES LINGERING OVER THE AREA FRI...EXPECT A SUNNY BUT
COOL DAY...THOUGH NOT AS COOL AS THU. SOME FROST COULD OCCUR AGAIN
FRI NIGHT...THOUGH THIS TIME MORE LIKELY OVER THE E...CLOSER TO
DEPARTING SFC HIGH. WARMING TREND WILL BE UNDERWAY SAT UNDER
CONTINUED RETURN FLOW AS HIGH PRES MOVES TO THE E COAST. HIGH TEMPS
SAT SHOULD BE CLOSER TO NORMAL.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 757 AM EDT SAT SEP 7 2013
PLENTY OF LOW LEVEL MOISTURE HAS RESULTED IN IFR-MVFR VIS AT SEVERAL
UPSTREAM AND DOWNSTREAM LOCATIONS. HOWEVER CMX...IWD...AND SAW
REMAINED MAINLY FOG FREE AS CLOUDS LINGERED AND SFC TEMPERATURES
REMAINED A LITTLE TOO WARM. WILL CONTINUE TO TRACK THE EXITING COLD
FRONT AND CONTINUED POTENTIAL FOR SCT-ISO SHOWERS AND TS THROUGH
EARLY AFTERNOON. HAVE KEPT THE MENTION OF SHOWERS OR TS OUT OF ALL
SITES /EXCLUDING VCTS AT CMX INITIALLY AS A CLUSTER OF TS PUSH
ACROSS THE KEWEENAW PENINSULA/. WITH DRY HIGH PRESSURE SLOWLY
PUSHING IN FROM THE NW THIS AFTERNOON EVENING...DO NOT EXPECT ANY
FOG TO DEVELOP TONIGHT. EXPECT WINDS AROUND 10KTS OR LESS
OVERNIGHT...UNDER A MOSTLY CLEAR SKY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 519 AM EDT SAT SEP 7 2013
A TROUGH WILL CONTINUE TO SINK SOUTH ACROSS THE UPPER GREAT LAKES
TODAY. BEHIND THE TROUGH...HIGH PRESSURE WILL BE ABLE TO SLIDE
IN...CROSSING LAKE SUPERIOR SUNDAY...BEFORE PUSHING ACROSS THE LOWER
GREAT LAKES SUNDAY NIGHT. ANY FOG THAT DEVELOPS WILL LIKELY SINK
SOUTH TODAY/TONIGHT AS DRIER AIR WORKS IN FROM THE N. A FEW GUSTS
NEAR 25KTS WILL BE POSSIBLE LATE TONIGHT THROUGH EARLY SUNDAY. LOW
PRESSURE ACROSS THE NORTHERN AND CENTRAL PLAINS SUNDAY NIGHT WILL
EDGE ACROSS THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. A BRIEF
RIDGE WILL FILTER IN TUESDAY NIGHT...OUT AHEAD OF A CENTRAL CANADIAN
LOW MOVING OVER HUDSON BAY ON WEDNESDAY. THIS LOW WILL BRING A
TROUGH TO LAKE SUPERIOR WEDNESDAY AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...KF
LONG TERM...ROLFSON
AVIATION...KF
MARINE...KF
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1043 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR IMAGERY SHOWING AN EXTENSIVE AREA OF STEADY RAIN AND A FEW
EMBEDDED LIGHTNING STRIKES OVER SOUTHERN ONTARIO AND LAKE ONTARIO
THIS MORNING. THIS AREA OF RAIN IS FASTER AND FARTHER SOUTH THAN ANY
MODEL GUIDANCE...SO TIMING AND PLACEMENT OF RAIN HAS BEEN ADJUSTED
FOR TODAY BY EXTRAPOLATION OF RECENT RADAR AND SATELLITE TRENDS.
HAVE BROUGHT THE STEADIER RAIN INTO THE COUNTIES ALONG AND SOUTHEAST
OF THE LAKE ONTARIO SHORE...WITH A FAIRLY SHARP CUTOFF TO LOWER
CHANCE POPS ACROSS THE SOUTHERN PORTION OF THE AREA AND ALSO IN THE
SAINT LAWRENCE VALLEY.
WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS SEVERAL MID LEVEL
SHORTWAVES MOVING THROUGH THE MEAN NORTHWEST FLOW ALOFT...WITH A
SUPPORTING MID LEVEL SPEED MAX NOTED IN OBJECTIVE RUC ANALYSIS FROM
NORTHERN LAKE HURON TO LAKE ONTARIO. THESE FEATURES ARE AIDING IN
LARGE SCALE ASCENT AND CONVERGENCE. SEASONABLY STRONG LOW/MID LEVEL
WARM ADVECTION AND ISENTROPIC UPGLIDE ARE ALSO FOUND TO THE
NORTHEAST OF A WARM FRONT ANALYZED NEAR LAKE HURON AT 12Z...AND IS
LIKELY PROVIDING THE NECESSARY CONCENTRATED ASCENT TO SUPPORT THE
AREA OF STEADY RAIN OVER LAKE ONTARIO.
WITH THICK CLOUD AND AN EARLIER ARRIVAL OF SHOWERS...TEMPERATURES
WILL STRUGGLE TO REACH 70 TODAY IN MANY AREAS. THE ONLY EXCEPTION
WILL BE ACROSS THE SOUTHERN TIER WHERE PLENTY OF DRY TIME WILL STILL
BE FOUND...WITH TEMPERATURES REACHING THE MID 70S IN THE VALLEYS
THERE.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
AN INITIAL WAVE OF SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS
LAKE ONTARIO THIS AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO
BUF/IAG/ROC/ART. CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY
WITH THIS GIVEN THE DRY LOW LEVELS NOTED ON THE 12Z KBUF SOUNDING.
ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING ALONG THE MAIN
COLD FRONT. THE MOST SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR
CIGS WHICH ARE LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO EASTERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. SMALL CRAFT ADVISORY CONDITIONS ARE ALSO LIKELY AGAIN
ON LAKE ERIE MAINLY FROM DUNKIRK TO THE PA STATE LINE AS NORTH TO
NORTHEAST WINDS INCREASE BEHIND THE COLD FRONT.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ041.
SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR LEZ040.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL/HITCHCOCK
MARINE...APFFEL/HITCHCOCK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
751 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SKIES WILL BE MOSTLY CLOUDY ACROSS THE REGION THIS MORNING.
DESPITE THE CLOUD COVER...EXPECT JUST A FEW SPRINKLES THIS
MORNING...WITH THE STEADIER SHOWERS HOLDING OFF UNTIL HE
AFTERNOON HOURS.
AN AREA OF SHOWERS NW OF LAKE ONTARIO AT DAYBREAK WILL CONTINUE TO
TRACK TOWARD OUR REGION. BUFKIT DATA FROM BOTH THE GFS/NAM LINK
THESE SHOWERS ALMOST EXCLUSIVELY TO LIFT IN THE UPPER
LEVELS...ABOVE 15K FEET. THESE SHOWERS ALSO LINE UP WITH A
DIFFLUENT UPPER LEVEL FLOW. WITH THE FEATURE ON RADAR WE HAVE
FAIRLY HIGH CONFIDENCE THAT IT WILL CONTINUE TO TRACK WITH THE 500
MB FLOW. THE GFS HAS CONSISTENTLY HAD THE BEST HANDLE ON
THIS...WITH THE HRRR ALSO LIKELY TO HANDLE THE ADVECTION OF A
FEATURE WELL. USING THE GFS/HRRR...EXPECT SHOWERS TO ENTER N OF
I-90 EARLY THIS AFTERNOON...WITH SHOWERS THEN SLIDING ESE INTO
THE FINGER LAKES AND EAST OF LAKE ONTARIO LATE AFTERNOON. WITH A
FEW LIGHTNING STRIKES UPSTREAM...CANNOT RULE OUT AN ISOLATED
THUNDERSTORM AS THE SHOWERS MOVE ACROSS LAKE ONTARIO. THE
SOUTHERN TIER SHOULD STAY DRY.
HIGHS WILL BE IN THE MID AND UPPER 70S IN MOST LOCATIONS...BUT EARLY
CLOUD COVER AND SPRINKLES WILL MAKE IT STRUGGLE TO REACH 70 EAST OF
LAKE ONTARIO. ALSO...TEMPERATURES WILL DROP AS THE SHOWERS MOVE
IN...SO HIGHS MAY COME LATE MORNING IN SOME SPOTS. A DECENT SW
BREEZE WILL DEVELOP OFF LAKE ERIE FROM BUFFALO TO NIAGARA FALLS.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT 12Z...TAF SITES SHOULD START OFF VFR. AN INITIAL WAVE OF
SHOWERS AHEAD OF A COLD FRONT WILL MOVE ACROSS LAKE ONTARIO THIS
AFTERNOON...AND SHOULD BRING SOME LIGHT RAIN TO BUF/IAG/ROC/ART.
CIGS/VSBY WILL PROBABLY REMAIN IN THE VFR CATEGORY WITH THIS. THEN
ANOTHER ROUND OF SHOWERS WILL DROP N-S THIS EVENING. THE MOST
SIGNIFICANT IMPACT TO AVIATION WILL BE MVFR/IFR CIGS WHICH ARE
LIKELY TO DEVELOP BEHIND THE COLD FRONT LATE TONIGHT.
OUTLOOK...
SUNDAY...MVFR CIGS LIFTING BY AFTERNOON.
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MAINLY VFR.
WEDNESDAY...MAINLY VFR. A CHANCE OF THUNDERSTORMS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO NORTHERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. CONDITIONS WILL BE CHOPPY ON LAKE ERIE AS
WELL...MARGINAL TO SCA CRITERIA. WINDS WILL DIMINISH SUNDAY NIGHT
AND MONDAY...AS HIGH PRESSURE BUILDS IN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR LEZ020-041.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...APFFEL
MARINE...APFFEL/TJP
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
622 AM CDT SAT SEP 7 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT SEP 7 2013
TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH
THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE
HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE
HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE
MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE
MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH
WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST
AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000
J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM
700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO
BECOME ALL THAT ORGANIZED OR SEVERE.
BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH
ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING
UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX
EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE
BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE
ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY.
QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL
SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN
CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT.
HAVE RAISED SKY COVER IN THE EAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT SEP 7 2013
EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD
BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA.
THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT
ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF
INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY
ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST.
SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW
SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT
INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY
A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM
TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD
MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED
GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH
DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70.
LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES
KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE
UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND
THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING
ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW
LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH
OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND
THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14
CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30
POP IN THAT REGION.
MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD
APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING
AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY
WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF
THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS
HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF
THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST
OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS
COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST.
CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER
MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST
FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING
DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT
ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE
BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT
DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS
WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE
NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND
THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT.
INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND
THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST
FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT
LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL
ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR
INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS.
MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH
PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION
PARALLEL TO THE FRONT.
BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS
NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER
AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO
WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH
HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS
MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A
WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE
RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT
MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE
COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN
SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS
SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY
HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT.
LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR
NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH
OF TEMPERATURES THE FOLLOWING WEEK.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 619 AM CDT SAT SEP 7 2013
A WEAK SHORT WAVE WILL MOVE THROUGH THE AREA THIS MORNING
RESULTING IN HIGH BASED ISOLATED-SCATTERED STORMS. EXPECT SKIES TO
BECOME PARTLY CLOUDY BEHIND THE WAVE. NORTHEAST FLOW WILL PREVAIL
ACROSS THE REGION BECOMING EASTERLY TONIGHT. THERE IS A CHACE THAT
STRATUS MAY TRY TO DEVELOP...THOUGH CONFDIENCE IS HIGHER EAST OF
I-29 AND HAVE NOT INCLUDED IN THE FORECAST QUITE YET.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
655 AM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE ACROSS THE REGION WILL SHIFT EAST PASSING OFF THE
COAST LATER THIS AFTERNOON AND EVENING. A WEAK COOL FRONT WILL
APPROACH FROM THE NORTHWEST LATE TONIGHT BEFORE SLIDING SOUTH
ACROSS THE REGION LATER SUNDAY...AND INTO THE CAROLINAS SUNDAY
EVENING. WEAK HIGH PRESSURE WILL BUILD SOUTH INTO THE AREA BEHIND
THE FRONT SUNDAY NIGHT AND THEN OFFSHORE THE MID ATLANTIC COAST
ON MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 210 AM EDT SATURDAY...
GRADIENT BETWEEN LOWER DEWPOINT AIR TO THE NORTH AND SOMEWHAT
MORE MOIST AIR TO THE SOUTH REMAINS ACROSS THE CENTRAL CWA EARLY
THIS MORNING. THIS IN COMBO WITH WEAK 9H SE UPSLOPE FLOW AND AN
AXIS OF HIGHER THETA-E ALONG THE SRN BLUE RIDGE HAS LED TO THE
DEVELOPMENT OF A STRATO-CU LAYER UNDER THE INVERSION FROM NW NC
INTO THE NEW RIVER VALLEY ATTM. EXPECT THIS CANOPY MAY INCREASE
SOME THROUGH DAYBREAK AS WELL AS FOG ALONG THE PERIMETER GIVEN
RIDGING OVERHEAD SO BEEFED UP CLOUDS/FOG TO INIT BUT STILL DRY.
OTRW WEAK MID LEVEL WAVE RIDING SOUTH THRU WVA WILL DROP
THROUGH THE REGION TODAY AS SURFACE HIGH PRESSURE GETS BUMPED
EAST. THIS SHOULD ALLOW THE LOW LEVEL FLOW TO QUICKLY VEER FROM
SOUTH/SE EARLY TO A MORE WESTERLY COMPONENT DURING THE AFTERNOON
AS THE WAVE ALOFT PASSES AND THE HIGH SLIDES OFFSHORE. LATEST
GUIDANCE RH FIELDS SHOW THIS ENOUGH TO SCOUR OUT RESIDUAL LOW
CLOUDS BY MID OR LATE MORNING WITH ONLY THE HRRR HANGING ONTO
CLOUDS ALONG THE SRN FOOTHILLS A BIT LONGER. THUS APPEARS
BECOMING MOSTLY SUNNY ON TRACK WITH ONLY SOME CU AND HIGH CLOUDS
AROUND WITH THE IMPULSE ALOFT THIS AFTERNOON ONCE ANY LOW DECK
FADES. MODELS DO SHOW A LOBE OF DECENT INSTABILITY AND WEAK
CONVERGENCE FAR SW INTO NW NC LATER THIS AFTERNOON SO AN ISOLD
MOUNTAIN TSRA CANT TOTALLY BE RULED OUT BUT TOO IFFY UNDER DRY
ENTRAINMENT TO INCLUDE MENTION FOR THE MOST PART. OTRW GIVEN A
MORE WESTERLY TRAJECTORY AND 85H WARMING OF A FEW DEGREES DURING
THE DAY...BUMPED UP HIGHS A LITTLE ESPCLY EAST WHERE EXPECT LOW
80S WITH MAINLY 70S ELSW.
NEXT COLD FRONT ACROSS THE GREAT LAKES LATER TODAY WILL BE
APPROACHING FROM THE NORTH LATE TONIGHT AND PERHAPS SPREADING
A PRECEDING BAND OF MID/HIGH CLOUDS IN FROM THE NW OVERNIGHT.
HOWEVER AIR AHEAD OF THE BOUNDARY REMAINS QUITE DRY ALOFT AND
GIVEN A STRONG NW TRAJECTORY THINKING MOSTLY CLEAR OVERALL UNDER
LINGERING HIGH PRESSURE. INCREASING WEST/NW WINDS ALOFT SHOULD
ALSO ACT TO KEEP TEMPS UP SOME ON THE RIDGES AHEAD OF THE
FRONT...WHILE THE VALLEYS AND SPOTS OUT EAST SPILL BACK INTO THE
MID/UPPER 50S FOR LOWS UNDER BETTER RADIATIONAL COOLING.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM EDT SATURDAY...
A COLD FRONT WILL MOVE THROUGH THE REGION ON SUNDAY IN
ASSOCIATION WITH AN UPPER TROUGH PROGRESSING THROUGH NEW ENGLAND.
GUIDANCE FOR THE PAST SEVERAL DAYS HAS FLIP-FLOPPED ON HOW
EXPANSIVE ANY ASSOCIATED PRECIPITATION WILL BE WITH THIS FEATURE
AS IT MOVES THROUGH OUR REGION. THIS MORNING/S FORECAST WILL BE
COMPARABLE TO THE ONE OFFERED YESTERDAY AFTERNOON...WITH SCATTERED
SHOWERS EXPECTED ACROSS THE MOUNTAINS BY THE AFTERNOON WITH
ISOLATED COVERAGE ACROSS ABOUT ONE TIER OF COUNTIES EAST OF THE
CREST OF THE BLUE RIDGE. ISOLATED THUNDERSTORMS ARE ALSO FORECAST.
TEMPERATURES WILL CONTINUE THEIR TREND OF BEING WARMER EACH DAY ON
SUNDAY PRE- COLD FRONT. AROUND 80 TO THE MID 80S ARE EXPECTED
ACROSS THE MOUNTAINS...WITH UPPER 80S COMMON ACROSS THE PIEDMONT.
BEHIND THE FRONT...HIGH PRESSURE WILL BUILD OFF THE MID-ATLANTIC
COAST AND FLOW AROUND THE HIGH WILL GRADUALLY USHER IN
SOUTHWEST FLOW INTO THE REGION...ESPECIALLY ACROSS THE WESTERN
PARTS OF THE AREA. THE INCREASED MOISTURE...DAYTIME HEATING...AND
A WEAK CAP WITH THE HIGH SO FAR OFF SHORE...WILL YIELD A SCENARIO
WHERE AFTERNOON CONVECTION IS EXPECTED. WITH NO ORGANIZED UPPER
LEVEL SUPPORT...COVERAGE IS EXPECTED TO BE ISOLATED TO SCATTERED
AT BEST. THE SOUTHWEST FLOW WILL ALSO ALLOW FOR A TREND OF MILDER
TEMPERATURES STARTING ON TUESDAY AFTER A BRIEF COOL DOWN ON
MONDAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 345 PM EDT FRIDAY...
HIGH PRESSURE WILL ADVANCE EAST OFF THE COAST OF NEW ENGLAND ON
TUESDAY...ALLOWING WINDS TO BECOME MORE SOUTHWESTERLY ACROSS THE
MID ATLANTIC...DRAWING DEEPER TROPICAL MOISTURE BACK INTO THE
REGION. AS SUCH...WE CAN EXPECT A RETURN OF AFTERNOON SHOWERS AND
THUNDERSTORMS...WITH INCREASING COVERAGE EACH DAY THROUGH THE
MIDDLE OF THE NEXT WORKWEEK. UPPER LEVEL RIDGING OVER THE CENTRAL
PLAINS WILL BUILD EAST THROUGH THE PERIOD...WHICH WILL RETURN A
MORE SUMMER LIKE FEEL TO THE REGION BY PUSHING TEMPERATURES
SLIGHTLY ABOVE NORMAL FOR THE EARLY HALF OF SEPTEMBER.
BY THURSDAY NIGHT...A LOW PRESSURE SYSTEM WILL PUSH ACROSS THE
GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. MAY SEE A FEW
STRONG TO SEVERE STORMS DEVELOP AHEAD OF THE FRONT...BUT RIGHT NOW
WILL BE A LITTLE MORE CONCERNED WITH THE POTENTIAL FOR HEAVY RAIN
DUE TO THE ABUNDANT ATMOSPHERIC MOISTURE ACROSS OUR AREA AND LIGHT
UPPER LEVEL WINDS...RESULTING IN POTENTIALLY SLOW MOVING STORMS.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 640 AM EDT SATURDAY...
WIDE VARIETY OF CONDITIONS TO INIT THIS MORNING WITH IFR/LIFR IN
FOG/STRATUS IN SOME OF THE VALLEYS SUCH AS LWB...AND LOW END MVFR
CIGS IN SPOTS OVER THE EAST LIKE DAN/LYH PER BANDS OF STRATO-CU.
OTRW OUTSIDE OF PATCHY LOW CLOUDS/FOG...MAINLY VFR UNDER PERIODIC
HIGH CLOUDS WITH A WEAK DISTURBANCE APPROACHING FROM THE NW. STILL
EXPECTING ANY LOW CLOUDS AND/OR FOG TO FADE BY MID OR LATE
MORNING IF NOT SOONER AS THE FLOW TURNS MORE SW TO W BY AFTERNOON.
HOWEVER WILL CONTINUE LOW CONDITIONS FOR A WHILE LONGER AND
PERHAPS SPILL LOW DECK WESTWARD BACK TO THE BLUE RIDGE BEFORE
TRANSITIONING ALL LOCATIONS TO A SCTD-BKN CU CANOPY WITH HEATING
THIS AFTERNOON.
SURFACE HIGH PRESSURE OVER SOUTHERN NEW ENGLAND WILL DRIFT SOUTH
TO ALONG THE MID ATLANTIC COAST BY THIS EVENING PROVIDING MAINLY
CLEAR SKIES OUTSIDE OF PASSING MID/HIGH CLOUDS OVERNIGHT. AGAIN
APPEARS THE DEEPER VALLEYS SUCH AS LWB WILL DROP OFF TO IFR/LIFR
AT TIMES WITH MAINLY VFR ELSW OUTSIDE OF PATCHY FOG LATE IN THE
EAST.
ANOTHER COLD FRONT...ARRIVING FROM THE NW...WILL MOVE INTO THE
AREA LATE SUNDAY...THEN STALL AND EVENTUALLY WASH OUT JUST TO OUR
SOUTH EARLY NEXT WEEK AS HIGH PRESSURE FROM THE MIDWEST BUILDS
EAST TOWARD THE MID-ATLANTIC. THIS MAY SPARK A ROUND OF SHRA/TSRA
ESPCLY MOUNTAINS SUNDAY AFTERNOON. OTRW EXPECT A RETURN TO MORE
TYPICAL SUMMERLIKE WEATHER WITH INCREASING CHANCES FOR DIURNALLY-
DRIVEN SHRA/TSRA INTO SUNDAY EVENING WHEN THE FRONT MOVES SOUTH
THROUGH THE REGION. APPEARS TO BE MOSTLY MVFR CIGS AT WORSE
OUTSIDE MORNING FOG/LOW CLOUDS WHICH WILL LIKELY BE INCREASING AS
THE AIR MASS ACROSS THE REGION BECOMES INCREASINGLY MOIST WITH
DEWPOINTS IN THE 60S MOUNTAINS AND NEAR 70 PIEDMONT. AT THIS
POINT...NO WIDESPREAD EXTENDED DURATION OF POOR AVIATION
CONDITIONS ARE EXPECTED THROUGH MID WEEK.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/WERT
NEAR TERM...JH
SHORT TERM...DS
LONG TERM...NF
AVIATION...JH/PM/WERT/WP
AREA FORECAST DISCUSSION
NWS SPOKANE WA
431 AM PDT Sat Sep 7 2013
.SYNOPSIS...
The low pressure system responsible for showers and thunderstorms
the last couple of days will bring another round of wet weather to
the Cascades and northern mountains again today. Sunday will be a
drier day for most of the Inland Northwest with showers limited to
mainly the Idaho Panhandle. Dry, summer-like weather will return
Monday through Thursday as a strong high pressure ridge develops
over the region.
&&
.DISCUSSION...
Today through Sunday...A large closed low near Republic will be
nearly stationary today...before moving east towards the North
Idaho Panhandle tonight...and then exiting the area into Montana
on Sunday.
For this morning main focus is the wrap around band near the North
Washington Cascades on the back side of the low where a steady
light rain has been falling around Stehekin. The HRRR has been
consistent with a large area of light rain over far southwest BC
dropping southeast into Mazama, Stehekin early this morning
spreading east into Chelan...Brewster...and the Waterville Plateau
during the mid morning hours. While this rain will be
light...additional rain on saturated ground where mud slides have
already occurred may result in additional slides although
confidence is marginal of this. Given uncertainty will continue
with current Flash Flood Watches for the East Slopes of the
Cascades and Wenatchee area. This wrap around band will swing
northeast towards Colville and Chewelah during the early
afternoon. Cloud cover associated with this may limit thunderstorm
chances this afternoon over the Northeast Washington Mountains and
Idaho Panhandle. West of this band over the Okanogan Highlands,
Okanogan Valley, and East Slopes of the Cascades a better
potential for isolated thunderstorms exists with sun breaks more
likely to develop. Less instability will exist from Spokane
southward due to further proximity from low with only isolated
showers at most expected for today. Cloud cover today will keep
temperatures below average over all of the region.
Tonight showers will decrease with the loss of daytime heating and
be confined mainly to northeast Washington and North Idaho with
the closed low tracking across this region. Then on Sunday showers
will continue in these areas although with the low departing out
of the area showers will only be scattered in nature with a slight
chance of afternoon thunderstorms. A short wave ridge will
approach the Cascades late Sunday afternoon which will allow for
more pronounced warming over Central Washington with less cloud
cover and showers compared to today. JW
Sunday Night: The exiting upper trough may yield some early
evening showers over the Idaho Panhandle, but 500mb temperatures
will be warming and instability profiles don`t suggest more than
isolated thunder potential prior to sunset.
Monday through Friday: Summer will return next week with
temperatures well above average. There is good model agreement
through about Thursday that a high amplitude high pressure ridge
will develop over the Pacific Northwest. Wednesday and Thursday
look to be the warmest days of the week with 850mb temperatures in
the 22-24C range. Many lowland areas will be in the upper 80s to
lower 90s which is about 10 degrees above average.
Forecast confidence diminished markedly Friday into next weekend.
There is very little agreement between the 00z models and run-to-
run consistency has not been good either. A cooling trend into
next weekend is probable, but the timing/track/intensity of an
incoming Pacific trough (and subsequent ridge breakdown) is
highly uncertain at this time. /GKoch
&&
.AVIATION...
06Z TAFS: Low pressure will remain over the region through 12z
Sunday. The low will be positioned over the northern mountains with
the bulk of the showers occurring in the Cascades and areas north of
the Columbia Basin. Isolated afternoon thunderstorms are also
expected in these areas. Several cloud layers will be present with
mid level clouds associated with the low as well as lower cloud
layers this morning due to abundant boundary layer moisture. CIGS
will be primarily VFR...with occasional MVFR CIGS possible around
Wenatchee, Moses Lake, and Spokane area TAFS.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 70 54 77 56 81 57 / 20 20 10 10 0 0
Coeur d`Alene 70 54 74 54 81 55 / 20 20 20 10 0 0
Pullman 72 49 75 49 81 49 / 10 10 10 10 0 0
Lewiston 80 57 83 59 87 59 / 10 10 10 0 0 0
Colville 70 50 81 51 85 51 / 70 30 20 10 0 0
Sandpoint 70 49 73 48 78 47 / 50 30 40 20 10 10
Kellogg 71 53 71 54 79 54 / 20 20 40 20 10 10
Moses Lake 74 53 84 55 86 55 / 20 10 0 0 0 0
Wenatchee 73 57 83 60 85 60 / 50 20 0 0 0 0
Omak 74 54 83 56 86 57 / 70 30 10 10 0 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flash Flood Watch through this evening for East Slopes Northern
Cascades-Wenatchee Area.
&&
$$
AREA FORECAST DISCUSSION
NWS TUCSON AZ
210 PM MST SAT SEP 7 2013
.SYNOPSIS...ABUNDANT MOISTURE WILL PRODUCE SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS THROUGH TUESDAY. A GRADUAL DECREASE IN
MOISTURE WILL THEN LEAD TO REDUCED SHOWER AND THUNDERSTORM ACTIVITY
DURING THE SECOND HALF OF THE UPCOMING WEEK.
&&
.DISCUSSION...PERSISTENT AREA OF SHOWERS CONTINUED ACROSS ERN
PIMA...SWRN GRAHAM...WRN COCHISE AND ERN SANTA CRUZ COUNTIES THIS
AFTERNOON. RADAR RAINFALL ESTIMATES AND GAUGE MEASUREMENTS RANGED
FROM JUST A FEW HUNDREDTHS OF AN INCH TO ABOUT 0.20 INCH DURING THE
PAST 3 HOURS. SEVERAL RUC HRRR SOLUTIONS MAINTAIN THIS AREA OF
SHOWERS DURING THE NEXT FEW HOURS FOLLOWED BY STRONGER PRECIP ECHOES
TO OCCUR THIS EVENING ACROSS GREENLEE/GRAHAM/COCHISE COUNTIES. HAVE
MAINTAINED SCATTERED SHOWERS AND ISOLATED TSTMS THRU TONIGHT.
SUN-MON...
OPTED TO INCREASE POPS GENERALLY 5-15 PERCENT THIS PERIOD. 07/12Z
GFS/ECMWF WERE SIMILAR WITH MOVING WEAK UPPER LOW OVER SRN SONORA
MIDDAY SUN NORTHWARD INTO FAR SE AZ BY MON AFTERNOON. NUMEROUS
SHOWERS AND ISOLATED THUNDERSTORMS SHOULD PREVAIL...PARTICULARLY SUN
NIGHT-MON AS SYSTEM MOVES INTO THE AREA. PER COORD WITH WFO/S PSR/
FGZ...HAVE OPTED TO DEFER ANY FLASH FLOOD WATCH ISSUANCES TO
SUBSEQUENT SHIFTS. WIDESPREAD RAINFALL SHOULD OCCUR. HOWEVER...MUCH
UNCERTAINTY EXISTS AT THIS TIME REGARDING THE POTENTIAL FOR
WIDESPREAD FLASH FLOODING.
TUE-WED...
THE PROSPECT FOR SEVERE THUNDERSTORMS MAY INCREASE PARTICULARLY TUE
AFTERNOON/EVENING AS AXIS OF DEEPER MOISTURE SHIFTS EWD INTO WRN NEW
MEXICO. MEANWHILE...MID-LEVEL DRYING IS PROGGED TO MOVE INTO WRN
SECTIONS IN RESPONSE TO SWLY FLOW ALOFT AROUND WEAK LOW PRESSURE
CENTERED OVER THE GREAT BASIN. THE INTERFACE BETWEEN THE DEEPER
MOISTURE JUST EAST OF THE AREA AND THE SOMEWHAT DRIER AIR WEST MAY
LEAD TO STRONGER THUNDERSTORMS TUE AFTERNOON AND TUE EVENING...AND
PERHAPS NEAR THE NEW MEXICO BORDER WED AFTERNOON.
THUR-SAT...
EXPECT SOMEWHAT LESS COVERAGE OF SHOWERS/TSTMS AS DEEPER MOISTURE IS
PROGGED TO REMAIN JUST EAST OF THIS FORECAST AREA. HAVE OPTED FOR
SCATTERED AFTERNOON AND EVENING SHOWERS/TSTMS ACROSS ERN SECTIONS
WITH ISOLATED SHOWERS/TSTMS FROM TUCSON WWD/NWWD.
HIGH TEMPS SUN WILL BE SIMILAR TO TEMPS ACHIEVED THIS AFTERNOON.
COOLER MON FOLLOWED BY NO SIGNIFICANT CHANGE IN DAYTIME TEMPS TUE.
HIGH TEMPS MON-TUE ARE FORECAST TO AVERAGE ABOUT 10 DEGS F OR SO
BELOW NORMAL. A WARMING TREND IS ON TAP WED-FRI...WITH DAYTIME TEMPS
FRI-SAT TRENDING CLOSE TO SEASONAL NORMALS FOR MID-SEPTEMBER.
&&
.AVIATION...VALID THRU 00Z 09/09.
SCT-BKN MID LVL CLOUD DECK HAS LIMITED CONVECTIVE POTENTIAL TODAY
FOR BOTH KOLS/KTUS. HOWEVER...THERE REMAINS AMPLE MOISTURE IN PLACE
SO CONTINUED -SHRA/VCSH POSSIBLE. CU FIELD DEVELOPING E OF THE KDUG
TO KSAD LINE SO GIVEN MID LVL STEERING FLOW ISOLD TS POSSIBLE THRU
03Z ACROSS THIS AREA. OUTSIDE OF A BRIEF +SHRA EXPECT VFR CONDITIONS
AND LIGHT WINDS TO PREVAIL THRU THE PERIOD. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
&&
.FIRE WEATHER...EXPECT SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS THROUGH TUESDAY. STRONG...GUSTY AND ERRATIC WINDS WILL
OCCUR WITH THE STRONGER THUNDERSTORMS. THEREAFTER...DECREASED
MOISTURE WILL LEAD TO ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS DURING THE LATTER PART OF THE UPCOMING WEEK. BELOW
NORMAL DAYTIME TEMPERATURES WILL OCCUR THROUGH WEDNESDAY FOLLOWED BY
A WARMING TREND THURSDAY AND FRIDAY.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON
DISCUSSION/FIRE WEATHER...FRANCIS
AVIATION...MEADOWS
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
115 PM PDT SAT SEP 7 2013
.SYNOPSIS...
SCATTERED THUNDERSTORMS WILL DIMINISH THIS EVENING OVER THE
MOUNTAINS...BUT MAY REFIRE AGAIN ON SUNDAY AFTERNOON WITH LINGERING
MONSOONAL MOISTURE. LOW PRESSURE WILL BE DEVELOPING ALONG THE WEST
COAST EARLY NEXT WEEK...BRINGING COOLER WEATHER AND DECREASING
THUNDERSTORM CHANCES OVER THE MOUNTAINS AND DESERTS.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
SHOWERS AND TSTMS GOT AN EARLY START LATE THIS MORNING OVER THE
MOUNTAINS...AND EXPECT IT WILL BE ANOTHER VERY ACTIVE AFTERNOON AND
EVENING. GPS SOUNDERS OVER THE DESERTS ARE ESTIMATING PW VALUES
AROUND TWO INCHES SO PLENTY OF FUEL FOR TORRENTIAL RAINFALL AGAIN
UNTIL AROUND SUNSET. A FEW TSTMS MAY POP OVER THE INLAND EMPIRE AS
WELL...BUT WATER VAPOR IMAGERY AND SOUNDERS WEST OF THE MOUNTAINS
SHOW THE MOIST LAYER IS SHALLOW. QUITE WARM TO HOT AGAIN THIS
AFTERNOON WITH TEMPS IN THE 80S NEAR THE COAST...AND 90S TO AROUND
100 F INLAND. VERY WEAK SFC PRESSURE GRADIENTS AT MIDDAY.
DUE TO THE VERY HIGH DEWPOINTS OVER THE LOWER DESERTS...THE
OPERATIONAL EMC RAP INDICATES SURFACE-BASED CAPES APPROACHING 3500
OVER THE LOWER DESERTS THIS AFTERNOON. SHOULD THIS AREA CONVECT...
THUNDERSTORMS COULD APPROACH SEVERE LIMITS AS WELL AS PRODUCE
TORRENTIAL DOWNPOURS. THE 18Z 3-KM HRRR HAS MODELED THE BEGINNING OF
THE CONVECTION WELL TODAY AND DOES NOT INDICATE ANY ACTIVITY IN THE
COACHELLA VALLEY THIS AFTERNOON. HOWEVER CONVECTION DOES BECOME
INTENSE OVER THE SANTA ROSAS...AND OVER THE SAN DIEGO COUNTY
DESERTS. NUMEROUS HRRR RUNS ALSO SHOW ISOLATED CONVECTION OVER THE
INLAND EMPIRE. ANY STORMS THAT DEVELOP OVER THE IE WILL WILL NOT
HAVE THE DEEP LAYER MOISTURE AVAILABLE OVER THE MTNS/DESERTS.
GLOBAL MODELS GENERALLY AGREE THE LARGE SUBTROPICAL HIGH...CENTERED
OVER THE GREAT PLAINS...WILL DRIFT EASTWARD THROUGH TUE...WHILE A
WEAK TROUGH DEVELOPS SOUTHWARD OVER SOCAL. THIS WILL ALLOW HEIGHTS/
THICKNESS TO DROP OFF ACROSS THE REGION...AND GRADUALLY ALLOW THE
MARINE LAYER TO BECOME REESTABLISHED NEXT WEEK. IN THE MEANTIME...
THE SLOW EASTWARD PROPAGATION OF THE TROUGH AXIS THROUGH THE REGION
SHOULD SHUNT THE DEEP LAYER MONSOONAL MOISTURE OFF TO THE EAST...
DECREASING THE TSTM CHANCES OVER THE MTNS/DESERTS NEXT WEEK.
REMNANTS OF TROPICAL STORM LORENA ARE DRAWN NORTHWARD AHEAD OF THE
TROUGH EARLY NEXT WEEK SO PLACEMENT OF THE DEVELOPING TROUGH AXIS IS
CRITICAL. BOTH THE 12Z ECMWF/GFS SHOW THE TROUGH AXIS E OF THE CWA
ON MON. THIS SHOULD KEEP THE BULK OF THE CLOUDS AND MOISTURE TO OUR
EAST AND THE 12Z ECMWF SEEMS TO BE TRENDING CLOSER THE THE GFS
SOLUTION. THE NAM 12 STILL SHOWS THE MTNS EAST CONVECTING ON
MON...BUT NO NOCTURNAL ACTIVITY OVER THE AREA. POPS HAVE BEEN PARED
BACK EARLY NEXT WEEK...EXPECTING THE BIGGER THREAT MORE TO THE EAST.
LOOKING AHEAD TO THE END OF NEXT WEEK...12Z GLOBAL MODEL RUNS STILL
DIVERGE OVER THE SW. BOTH THE GFS/ECMWF LOOK DRY...BUT THE GFS IS
FAVORED AND A BIT WARMER.
&&
.AVIATION...
072010Z...COAST/VALLEYS...FROM 2100 UTC THROUGH 08/0300
UTC...THUNDERSTORMS OVER MTNS WILL PRODUCE SCT-FEW DEBRIS CLDS AOA
8000 FT MSL OVER THE COAST/VALLEYS. SLIGHT CHANCE OF FOG REACHING
KSAN...KCRQ...AND/OR KSNA DURING THE 08/1100-1500 UTC
TIME-FRAME...BUT CONFIDENCE IS LOW IN THIS OCCURRING.
OTHERWISE...UNRESTRICTED VIS AND MOSTLY SKC THROUGH SUNDAY MORNING.
MTNS/DESERTS...ISOLATED TO SCATTERED THUNDERSTORMS THROUGH 08/0100
UTC WITH BASES 7000-10000 FT MSL AND CB TOPS TO 40000 FT
MSL...RESULTING IN LOCAL VIS AOB 2SM IN HEAVY RAIN...SMALL
HAIL...AND POSSIBLE STRONG UP/DOWNDRAFTS. OTHERWISE...UNRESTRICTED
VIS THROUGH SUNDAY MORNING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FLASH FLOOD WATCH FROM 11 AM PDT TODAY THROUGH THIS EVENING FOR
THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY...RIVERSIDE
COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO
COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS.
PZ...NONE.
&&
$$
PUBLIC...JAD
AVIATION...HARRISON
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1059 AM MDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1057 AM MDT SAT SEP 7 2013
AN AREA OF LIGHT SHOWERS WITH A LIGHTNING STRIKE EVERY SO
OFTEN...CONTINUES TO MOVE NORTH ACROSS NORTHWEST COLORADO THIS
MORNING. THIS ACTIVITY WAS LOCATED FROM THE VICINITY OF THE
CATHEDRAL BLUFFS IN WESTERN RIO BLANCO COUNTY TO WEST OF HIGHWAY
13 FROM HAMILTON/CRAIG TO BAGGS WY LATE THIS MORNING. THESE
SHOWERS WILL CONTINUE NORTHWARD INTO WY BY NOON OR SHORTLY
THEREAFTER. OTHERWISE CONVECTION IS JUST STARTING TO BUILDUP OVER
THE HIGHER TERRAIN WITH THAT TREND EXPECTED TO CONTINUE INTO THE
AFTERNOON AS PER PREVIOUS FORECAST.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
ISOLATED THUNDERSTORMS FIRING ACROSS PORTIONS OF NORTHEAST ARIZONA
THIS MORNING...BASICALLY SOUTH OF MEXICAN HAT...AND ALONG THE
UNCOMPAHGRE PLATEAU SOUTH AND EAST OF GATEWAY. THE ARIZONA
ACTIVITY APPEARS TO BE ASSOCIATED WITH WEAK WAVE LIFTING NORTH
NORTHWEST ACROSS THAT AREA...WHICH SHOWS UP NICELY IN POT VORT
FIELDS ON THE 00Z NAM AND GFS. THIS WAVE WILL CONTINUE TRACKING
TOWARD THE FOUR CORNERS THIS MORNING...BEFORE DAMPENING OUT
SHORTLY AFTER SUNRISE.
THE CELLS EAST OF GATEWAY ALONG THE UNCOMPAHGRE PLATEAU APPEAR TO
BE FIRING ALONG AN OLD OUTFLOW BOUNDARY FROM LAST EVENING THAT WAS
EVIDENT ON RADAR IMAGERY EARLIER THIS MORNING. LIGHTNING ACTIVITY
HAS BEEN ON THE INCREASE OVER THE PAST HOUR AND LIKELY WILL
CONTINUE FOR ANOTHER COUPLE HOURS.
HRRR DOING A DECENT JOB WITH PICKING UP THIS ACTIVITY AND DRIVING
IT NW AND N THIS MORNING...ENDING AROUND 14Z OR SHORTLY AFTER
SUNRISE. THIS SOLUTION REASONABLE AND WILL GEAR POPS IN THIS
DIRECTION...BUT BACK OFF AREAL COVERAGE DISPLAYED IN THE HRRR AS
IT APPEARS TO BE A BIT AGGRESSIVE ACROSS SE UTAH. ONCE THIS
ACTIVITY DIMINISHES...WILL TAKE A FEW HOURS TO RE-FIRE
CONVECTION...BUT IT WILL AND FOCUS FOR THE AFTERNOON HOURS WILL BE
ACROSS THE HIGHER TERRAIN AND PORTIONS OF SOUTHEAST UTAH AS THE
DEEPER PLUME NUDGES EAST A BIT AS THE UPPER LOW ACROSS THE PACNW
STARTS TO FEEL THE INFLUENCE OF KICKING SYSTEM MOVING INTO WESTERN
CANADA. THINGS GET A LOT MORE INTERESTING SUNDAY AND MONDAY...
WHICH IS DISCUSSED BELOW AS THE PLUME LEANS OVER AND INTO OUR
FORECAST AREA. UNTIL THEN...ANOTHER HOT DAY WITH TEMPERATURES
RUNNING 5 TO 10 DEGREES ABOVE NORMAL FOR AFTERNOON HIGHS.
TONIGHT THE UPPER LOW TRACKS INTO THE NORTHERN ROCKIES DRAGGING A
TROUGH INTO THE WESTERN GREAT BASIN. IN TIGHTENING SW FLOW
ALOFT...MOISTURE AND LOW LEVEL CONVERGENCE INCREASE IN SE UTAH
OVERNIGHT. SO SOME THUNDERSTORMS ARE EXPECTED TO PERSIST OVERNIGHT
PERHAPS SPREADING INTO NE UTAH AND FAR WESTERN COLORADO. CLOUDS
AND WINDS WILL KEEP OVERNIGHT LOW TEMPERATURES ABOVE NORMAL.
SUNDAY THE PACIFIC TROUGH SHIFTS INTO CENTRAL UTAH. ONE INCH
PRECIPITABLE WATER VALUES REACH INTO THE NORTHERN CWA. A WEAK
SURFACE COLD FRONT WORKS ACROSS THE CO-WY BORDER IN THE AFTERNOON
PROVIDING A FOCUS FOR CONVECTION. WIDESPREAD CLOUDY SKIES WILL
LOWER AFTERNOON TEMPERATURES TO WITHIN A FEW DEGREES OF NORMAL.
GUSTY AFTERNOON WINDS EXPECTED DUE TO GRADIENT PLUS CONVECTIVE
COMPONENTS. SOME MID-LEVEL COOLING WILL INCREASE INSTABILITY
ESPECIALLY OVER NE UT-FAR NW CO.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 358 AM MDT SAT SEP 7 2013
SUNDAY NIGHT THROUGH MONDAY NIGHT...THE UPPER LOW TRACKS ONTO THE
NORTHERN PLAINS ON MONDAY LEAVING A WEAK TROUGH OVER THE GREAT
BASIN. THE 40KT JET TAIL TRACKS THROUGH SOUTHERN WYOMING SUNDAY
NIGHT LEAVING A SECOND STRONGER COOL FRONT LAYING WEST TO EAST
NEAR THE WYOMING BORDER ON MONDAY. WITH THE WET BULB ZERO LEVEL
BELOW 14KFT...HAIL IS POSSIBLE WITH THE STRONGEST STORMS.
TEMPERATURES FALL TO NEAR/SOUTH OR BELOW/NORTH NORMAL ON MONDAY.
DRIER AIR TRIES TO INVADE NE UTAH MONDAY NIGHT.
THE STAGNANT RIDGE OVER THE PLAINS AND LOW ACROSS THE PACNW
PATTERN WILL BE BREAKING DOWN MONDAY AND TUESDAY...WITH LONG WAVE
TROUGH FINALLY PUSHING EAST ACROSS THE ROCKIES. THIS WILL DRIVE A
LITTLE COOLER AIR INTO THE REGION AS TEMPERATURES DROP BACK TO
MORE SEASONAL VALUES. HOWEVER...CONVECTIVE POTENTIAL WILL REMAIN
IN PLAY FOR MUCH OF THE WEEK AS THE BREAK DOWN AND SWEEP OUT OF
MOISTURE WILL BE SHORT-LIVED WITH THE PLAINS RIDGE REBUILDING BY
THURSDAY. THIS KEEPS THE MONSOON ACTIVE FOR A FEW MORE DAYS WITH
ANOTHER SURGE OF MOISTURE LIFTING ACROSS THE FORECAST AREA AS WE
CLOSE OUT THE WEEK. SO UNSETTLED CONDITIONS WILL CONTINUE WITH
SLIGHTLY MODERATION FROM THE PERSISTENT HEAT THE REGION HAS BEEN
EXPERIENCING.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1057 AM MDT SAT SEP 7 2013
ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
WILL DEVELOP THIS AFTERNOON...FAVORING THE HIGHER TERRAIN. GUSTY
AND ERRATIC OUTFLOW WINDS...HEAVY RAIN AND SMALL HAIL WILL BE
ASSOCIATED WITH THE STRONGER THUNDERSTORMS THROUGH 03Z THIS
EVENING. MOISTURE WILL CONTINUE TO SURGE BACK INTO THE REGION
AFTER 06Z TONIGHT WITH SHOWERS LINGERING THROUGH THE NIGHT. EXPECT
LOCAL MVFR CIGS AND VSBYS NEAR THE STRONGER THUNDERSTORMS THIS
AFTERNOON...ESPECIALLY ACROSS THE MOUNTAINS.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
UPDATE...EH
SHORT TERM...JDC/JOE
LONG TERM...JOE/JDC
AVIATION...EH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
408 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 21Z...
* OUTFLOW BOUNDARY SURGING SOUTH-SOUTHWEST AND IS EXPECTED TO
PRODUCE A WIND SHIFT TO NORTHEAST AT BOTH ORD/MDW BETWEEN
2115-2130Z. WIND LIKELY TO GUST BRIEFLY AROUND 20 KT...THEN
BECOME MORE EAST/SOUTHEAST OVER NEXT FEW HOURS.
* SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING.
* SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
ALLSOPP/RATZER
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* HIGH CONFIDENCE IN OUTFLOW WINDSHIFT AT ORD...MEDIUM-HIGH MDW TO
NORTHEAST SHORTLY.
* MEDIUM-HIGH CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING
EARLY THIS EVENING.
* MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH
CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
ALLSOPP/RATZER
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
325 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
MAINTAINED BLENDED GUIDANCE FOR MID-HIGH CHANCE POPS TUESDAY
EVENING/NIGHT WITH COLD FRONT BUT IF FRONT SLOWS
FURTHER...INSTABILITY MAY WANE ENOUGH TO GREATLY LIMIT COVERAGE OF
SHRA/TSRA. THEN ON WEDNESDAY...THE FRONT WILL STILL BE DROPPING
SOUTHWARD...KEEPING A CHANCE FOR THUNDER GOING. AIR MASS WILL ONLY
BE MODESTLY COOLER INITIALLY. THEN A MUCH COOLER AIRMASS WILL
FINALLY ARRIVE THURSDAY INTO FRIDAY AS EASTERN NOAM TROUGH DEEPENS
AND BRUSHES OUR AREA WHILE STRONG CANADIAN HIGH PRESSURE SPREADS
SOUTHWARD. 850 MB THERMAL TROUGH LOOKS TO ARRIVE THURSDAY NIGHT INTO
FRIDAY...WITH MID TO HIGH SINGLE DIGITS AT 850 MB. SO AFTER A COOLER
BUT BASICALLY SEASONABLE THURSDAY...FRIDAY WILL BE A TASTE OF AUTUMN
WITH HIGHS ONLY IN THE LOW-MID 70S AWAY FROM LAKE MICHIGAN AND
MID-UPPER 60S ON THE LAKEFRONT. HEIGHT RISES WILL QUICKLY RETURN
SATURDAY SO TEMPERATURES WILL WARM SLIGHTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* DYING OUTFLOW BOUNDARY APPROACHING AIRPORT BUT NOT EXPECTED TO
CAUSE A WIND SHIFT AT ORD.
* SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING.
* SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
ALLSOPP
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY
THIS EVENING.
* MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH
CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 PM CDT SAT SEP 7 2013
.DISCUSSION...
SHORT TERM...TONIGHT THROUGH TUESDAY...
FORECAST CONCERNS INCLUDE SHRA/TSRA CHANCES THIS EVENING INTO
TONIGHT AND THEN A BLAST OF LATE SEASON HEAT MONDAY INTO TUESDAY.
THE PRIMARY CONCERN IN THE NEAR TERM IS WITH SHOWER AND THUNDER
CHANCES THROUGH THIS EVENING. A COLD FRONT IS SLOWLY SINKING SOUTH
FROM SOUTHERN WISCONSIN AND A PEAK AT WATER VAPOR IMAGERY SHOWS
DISTURBED MODERATE NW FLOW ALOFT WITH A SHORT WAVE PUSHING SOUTHEAST
ACROSS THE UPPER MS VALLEY. HI-RES GUIDANCE SUCH AS THE HRRR INSISTS
ON CONVECTION LATER THIS AFTERNOON AND THIS EVENING. ALSO MOST
GUIDANCE FAVORED THE IDEA OF BETTER MOISTURE CONVERGENCE FOCUSING
THIS EVENING OVER THE WEST/SW CWA AND POINTS SW ALONG SWD MOVING
COLD FRONT AND A WEAK SURFACE WAVE STRETCHING ACROSS THE MID MS
VALLEY. HOWEVER...GIVEN LACK OF AGITATED CU UPSTREAM OVER WISCONSIN
AND NORTHEAST IOWA...CONFIDENCE IN THIS SCENARIO IS LOW AND WILL
MAKE A LAST MINUTE DECISION ON POPS BEFORE PUBLISHING GRIDS. HAD
INDICATED HIGH CHANCE RANGE POPS EARLY FOR THE NORTH HALF SHIFTING
INTO THE SW CWA LATER THIS EVENING...BUT CURRENT THINKING IS THESE
POPS MAY BE TOO HIGH.
ONCE THE COLD FRONT FINALLY DOES PUSH THROUGH MOST OF THE CWA LATE
TONIGHT...GUSTY NORTHEAST FLOW WILL DEVELOP OVER THE LAKE AND LOW
CLOUDS ARE EXPECTED TO DEVELOP. BASED ON FORECAST SOUNDINGS AND LOW
LEVEL RH ON THE MODELS...THESE LOW CLOUDS SHOULD HANG
ON...ESPECIALLY FOR THE NORTHERN CWA INTO THE EARLY AFTERNOON BEFORE
FINALLY ERODING. THE COOLER AIR MASS...CLOUD COVER AND NORTHEAST
FLOW WILL RESULT IN TEMPERATURES ONLY IN THE 70S/POSSIBLY LOW 70S
NEAR LAKE MICHIGAN NORTH OF I-80 AND LOW-MID 80S SOUTH WHERE CLOUDS
MAY ERODE QUICKER AND WARMER THERMAL PROFILES EXIST. CONCERNED THAT
STALLING COLD FRONT COULD SERVE AS A FOCUS FOR SPOTTY TSRA
DEVELOPMENT IN THE SRN CWA SO BUMPED UP POPS A BIT. ALSO...IN
DISTURBED NW FLOW...MODELS EVEN GENERATING QPF FARTHER NORTH...BUT
MAINTAINED A DRY FORECAST FOR NOW.
VERY STRONG WARM ADVECTION WILL ENSUE ALOFT TOMORROW NIGHT AS HOT
AIR MASS OVER THE PLAINS RUSHES EASTWARD IN RESPONSE TO STRONG LOW
PRESSURE OVER THE NORTHERN PLAINS LIFTING NORTHEAST. THE LOW
PRESSURE AREA WILL LIFT THE FRONT STALLED TO OUR SOUTH BACK NORTH AS
A WARM FRONT ON MONDAY. ANY EARLY MORNING CLOUDS OVER THE NORTHEAST
HALF OF CWA WILL SHIFT NORTHEAST BY LATE MORNING. MODEL THERMAL
PROFILES HAVE COME IN VERY WARM/IE 850 MB TEMPS AROUND 20C AND 925
MB TEMPS IN THE MID TO UPPER 20SC BY LATE DAY. THUS TRENDED HIGHS A
FEW DEGREES WARMER THAN PREVIOUS FORECAST. A VERY WARM NIGHT FOR
SEPTEMBER IS THEN IN STORE ON MONDAY NIGHT...MAYBE NOT DROPPING OUT
OF THE UPPER 70S IN DOWNTOWN CHICAGO. THIS WILL PROVIDE A
SPRINGBOARD FOR POTENTIAL RECORD/NEAR RECORD WARMTH ON TUESDAY.
GUSTY SOUTHWEST FLOW AND DEEP MIXING OF LOW 20S AT 850 AND UPPER 20S
AT 925 MB AIRMASS WILL SUPPORT HIGHS SOLIDLY INTO THE MIDDLE 90S FOR
MOST OF THE AREA...IF NOT WARMER FOR A FEW SPOTS. A COLD FRONT WILL
BE SAGGING SOUTH AND IS A WILD CARD FOR TEMPS IN THE NORTHERN CWA
BUT WITH SUCH A HOT AIR MASS...CONTINUE TO FAVOR THE IDEA OF FRONTAL
PASSAGE DURING THE EVENING...WHICH WILL KEEP CLOUDS AND THUNDER
CHANCES MAINLY IN THE EVENING. AS ALLUDED TO YESTERDAY...THE SAVING
GRACE FOR THIS LATE SEASON HEAT WILL BE FAIRLY DRY CONDITIONS/TD
ONLY IN THE LOW-MID 60S.
LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...
WILL BE ISSUED SHORTLY.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* DYING OUTFLOW BOUNDARY APPROACHING AIRPORT BUT NOT EXPECTED TO
CAUSE A WIND SHIFT AT ORD.
* SCATTERED THUNDERSTORMS MAY DEVELOP EARLY THIS EVENING.
* SOUTHWEST WINDS DIMINISHING AND BECOMING NE THIS EVENING
* LOW MVFR CIGS LIKELY DEVELOPING LATE TONIGHT/EARLY SUNDAY
MORNING.
ALLSOPP
//DISCUSSION...UPDATED 18Z...
SYNOPSIS...WARM MOIST SOUTHWEST FLOW AHEAD OF A WEAK COLD FRONT...
WHICH EXTENDED FROM NORTHERN LAKE MICHIGAN ACROSS CENTRAL WI TO NW
IA THIS AFTERNOON. THE FRONT WILL MOVE THROUGH NORTHERN ILLINOIS
THIS EVENING. HIGH PRESSURE WILL BUILD INTO THE NORTHERN GREAT
LAKES SUNDAY WITH STRONG NORTHEAST WINDS DEVELOPING.
THUNDERSTORM CLUSTER OVER SOUTHEAST WI MOVING SOUTHEAST BUT NEW
DEVELOPMENT AHEAD AND WEST OF MAIN CLUSTER OF STORMS MAY CLIP FAR
NORTHEAST ILLINOIS MID TO LATE AFTERNOON. WEAK INSTABILITY AND
SOMEWHAT OF A CAP WILL LIMIT DEVELOPMENT AND EXPECT MOST OF THIS
ACTIVITY TO DRIFT ACROSS LAKE MICHIGAN. HAVE ADDED A VCTS FOR LOW
CHANCE OF THUNDER NEAR ORD THIS AFTERNOON.
INSTABILITY WILL CONTINUE TO BUILD THROUGH THE AFTERNOON. CONVERGENCE
ALONG THE FRONT WILL BE FAIRLY WEAK BUT SHOULD BE SUFFICIENT FOR
SCATTERED THUNDERSTORMS AHEAD OF AND ALONG THE COLD FRONT EARLY
THIS EVENING. THUNDERSTORMS SHOULD DIMINISH AND SHIFT SOUTH LATE
THIS EVENING. BEHIND THE FRONT WINDS WILL BECOME NORTHEAST. WINDS
WILL INCREASE TOWARDS MORNING. MODEL GUIDANCE SUGGESTING LOW MVFR
AND POSSIBLY EVEN IFR CIGS WILL DEVELOP BEHIND THE COLD FRONT. LOW
CIGS SHOULD LIFT BY AFTERNOON. EXPECT NORTHEAST WINDS 12 TO 20 KTS
THROUGH THE DAY SUNDAY.
ALLSOPP
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* MEDIUM CONFIDENCE IN SCATTERED THUNDERSTORMS DEVELOPING EARLY
THIS EVENING.
* MEDIUM CONFIDENCE IN WIND FORECAST THROUGH MID EVENING. HIGH
CONFIDENCE IN WIND FORECAST LATE TONIGHT AND SUNDAY.
* MEDIUM TO HIGH CONFIDENCE IN MVFR CIGS DEVELOPING LATE TONIGHT
BUT LOW TO MEDIUM CONFIDENCE IN TIMING.
ALLSOPP
//OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z...
SUNDAY NIGHT THROUGH TUESDAY...VFR.
TUESDAY NIGHT AND WEDNESDAY...CHANCE TSRA WITH MVFR POSSIBLE.
WEDNESDAY THROUGH FRIDAY...VFR.
MDB
&&
.MARINE...
129 PM CDT
A COLD FRONT IS BEGINNING TO MOVE ACROSS THE NORTHERN PORTION OF
LAKE MICHIGAN EARLY THIS AFTERNOON. THIS FRONT WILL SWEEP DOWN THE
LAKE INTO THIS EVENING...WITH WINDS RAPIDLY SHIFTING OUT OF THE
NORTH-NORTHEAST IN ITS WAKE. IT STILL APPEARS THAT A PERIOD OF 15 TO
25 KT WINDS WILL SET ACROSS THE LAKE TONIGHT INTO SUNDAY WITH A
DECENT PRESSURE GRADIENT AHEAD OF A SURFACE HIGH BUILDING
SOUTHEASTWARD FROM ONTARIO. THIS LOOKS TO SET UP HAZARDOUS
CONDITIONS FOR SMALL CRAFT...WITH WAVES UP TO 7 FEET...MAINLY FOR
THE NORTHEAST ILLINOIS SHORES. WITH THIS IN MIND I ISSUED A SMALL
CRAFT ADVISORY LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR ALL
BUT THE PORTER INDIANA NEAR SHORE ZONE...WHERE SLIGHTLY LOWER WAVES
ARE EXPECTED.
THE WINDS ARE EXPECTED TO VEER TO THE EAST-SOUTHEAST
SUNDAY NIGHT INTO MONDAY AS THE SURFACE HIGH SHIFTS FROM THE UPPER
GREAT LAKES ACROSS THE NORTHEASTERN U.S. THIS COULD LEAD TO A
CONTINUATION OF NEAR 4 FOOT WAVES INTO MONDAY FOR THE ILLINOIS
SHORES. THIS COULD RESULT IN THE SMALL CRAFT ADVISORY NEEDING TO BE
EXTENDED...BUT DUE TO THE MARGINAL WAVE MAGNITUDES...I WILL HOLD OFF
ON EXTENDING THE ADVISORY INTO THIS PERIOD.
THE WINDS SHOULD BECOME SOUTHERLY AGAIN BY MONDAY...BUT SPEEDS WILL
LIKELY REMAIN FAIRLY HIGH...25 TO 30 KT...AS A POTENT AREA OF LOW
PRESSURE MOVES EAST-NORTHEASTWARD ACROSS THE DAKOTAS AND MINNESOTA.
LATER IN THE WEEK...IT APPEARS THAT A POTENT COLD FRONT COULD DROP
ACROSS THE LAKE...LEADING TO SOME STRONGER NORTHERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741...4 AM SUNDAY TO 11 PM
SUNDAY.
SMALL CRAFT ADVISORY...LMZ742-LMZ743-LMZ744...10 AM SUNDAY TO 11
PM SUNDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
106 PM CDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 709 AM CDT SAT SEP 7 2013
FORCING IN THE 600-500MB LAYER IS CAUSING THE LINE OF SPRINKLES/LIGHT
SHOWERS AND THE ONE OR TWO THUNDERSTORMS ACROSS THE CWFA. WHERE
RAIN IS REACHING THE GROUND IT IS MAINLY A TRACE OR A FEW
HUNDREDTHS.
PER THE RAP TRENDS...THIS FEATURE WILL CLEAR THE CWFA BY MID
MORNING. ANOTHER AREA OF FORCING ARRIVES ALMOST IMMEDIATELY BEHIND
THE DEPARTING LINE. THUS ISOLATED TO SCATTERED SPRINKLES/LIGHT
SHOWERS CAN BE EXPECTED FOR THE MORNING.
DAYTIME HEATING WITH THE SECOND AND THEN THIRD ROUND OF FORCING
ALOFT IS EXPECTED TO INITIATE ISOLATED TO LOW END SCATTERED
SHOWERS AND SOME THUNDERSTORMS DURING THE AFTERNOON AND INTO THE
EVENING HOURS. ..08..
&&
.SYNOPSIS...
ISSUED AT 324 AM CDT SAT SEP 7 2013
06Z SFC ANALYSIS HAS WEAK LOWS AT KANW AND KSTC WITH WEAK
BOUNDARIES/FRONTS FROM THE NE/SD BORDER INTO MINNESOTA AND
WISCONSIN. DEW POINTS WERE MAINLY IN THE 60S ACROSS THE MIDWEST WITH
50S OVER THE EASTERN GREAT LAKES.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 324 AM CDT SAT SEP 7 2013
RADAR TRENDS SHOW SHOWERS AND A FEW STORMS FROM EASTERN WISCONSIN
BACK THROUGH KAUW. SOME SPRINKLES WERE OCCURRING ACROSS CENTRAL IOWA.
SATELLITE AND MODELS SHOW A VERY WEAK SHORTWAVE MOVING FROM
MINNESOTA THROUGH WISCONSIN DURING THE DAY WHILE AN EVEN WEAKER ONE
PASSES TO THE SOUTH/WEST OF THE CWFA. AT BEST A FEW SPRINKLES MAY
OCCUR THIS MORNING ACROSS THE NORTHEAST CWFA.
THIS AFTERNOON...THE SITUATION IS MORE UNCERTAIN. WARM TEMPERATURES
ALOFT MAY PRECLUDE ANY DIURNAL CONVECTION FROM OCCURRING. HAVE OPTED
TO MAINTAIN THE SCHC POPS IN THE NORTHEAST CWFA FROM LATE AFTERNOON
ON. IF CONVECTION OCCURS...OVERALL COVERAGE MAY BE 5 PERCENT AT BEST.
MOISTURE POOLING NEAR THE FRONT/BOUNDARY SHOULD RESULT IN MID AND
UPPER 60 DEW POINTS ACROSS THE AREA. THIS MOISTURE COMBINED WITH
TEMPERATURES IN THE UPPER 80S TO MID 90S MAY PUSH HEAT INDEX VALUES
CLOSE TO 100 IN THE SOUTHWEST/WEST CWFA DURING THE AFTERNOON.
TONIGHT...THE OVERALL FORCING IS QUITE WEAK AND CONFINED RIGHT
AROUND THE FRONT/BOUNDARY AND BEHIND IT. THUS WILL MAINTAIN THE SCHC
POPS FOR TONIGHT BUT THE OVERALL SITUATION SUGGESTS A MAJORITY OF
THE AREA WILL REMAIN DRY TONIGHT. ..08..
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 324 AM CDT SAT SEP 7 2013
IN THE NEAR TERM THE MAIN CONCERN WITH BE RAIN CHANCES SUNDAY
ASSOCIATED WITH A STALLED FRONTAL BOUNDARY OVER NORTHERN MO. THE
SHORT RANGE MODELS SHOW THE SURFACE BOUNDARY JUST SOUTH OF THE
FORECAST AREA SUNDAY MORNING...BUT KEEP THE H8 BOUNDARY OVER THE
SOUTHERN CWFA. WITH WEAK CONVERGENCE NEAR THE H8 BOUNDARY AND
SURFACE BASED CAPES AROUND 2K J/KG A FEW STORMS ARE POSSIBLE. WEAK
FORCING AND WARM MID LEVEL TEMPS SHOULD KEEP COVERAGE OF SHRA/TSRA
ISOLATED SO KEPT POPS IN THE SLIGHT CHANCE RANGE.
THE LATE SUMMER/EARLY FALL HEAT WILL RETURN TO THE AREA MONDAY AS
THE SURFACE BOUNDARY LIFTS NORTH IN RESPONSE TO LOW PRESSURE MOVING
THROUGH THE NORTHERN PLAINS. AT THIS TIME IT APPEARS THE WARM FRONT
WILL NOT REACH THE NORTHERN CWFA UNTIL LATE AFTERNOON MAKING IT
UNLIKELY THAT THE 90 DEGREE TEMPERATURES WILL REACH NORTHWEST
IL...BUT THE REST OF THE AREA SHOULD SEE HIGHS IN THE LOW TO MID 90S.
SOUTHWEST WINDS SHOULD CONTINUE THROUGH THE NIGHT KEEPING TUESDAYS
LOWS NEAR 70. THE HOT WEATHER WILL CONTINUE TUESDAY AS A COLD
FRONT MOVES THROUGH NORTHWEST IA. GUSTY SOUTHWEST WINDS AHEAD OF
THE FRONT AND PLENTY OF SUN SHOULD HELP THE LOW LEVELS MIX TO AT
LEAST H8 YIELDING LOW TO MID 90S AGAIN FOR HIGHS. THE NORTHWEST MAY
BE THE EXCEPTION WITH CLOUDS EXPECTED TO INCREASE DURING THE
AFTERNOON SUPPRESSING THE HEATING SOME. A LOW THREAT OF SHRA/TSRA
WAS MENTIONED IN THE NORTH...SINCE THE FRONT WILL BE NEARBY 00Z.
TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT WILL DROP SOUTH THROUGH
THE FORECAST AREA...BRINGING WITH IT THE BEST CHANCE OF RAIN MOST OF
THE AREA HAS HAD IN RECENT WEEKS. POPS STILL WERE KEPT IN THE HIGH
CHANCE CATEGORY MAINLY BECAUSE UPPER FLOW LOOKS CONVERGENT TUESDAY
NIGHT WHICH COULD HAMPER THE DEVELOPMENT OF SHRA/TSRA. CHANCE
POPS WERE CONTINUED OVER MOST OF THE AREA WEDNESDAY THEN TAPERED
BACK TO SLIGHT CHANCE FOR WEDNESDAY NIGHT AS THE FRONT MOVES SOUTH
OF THE FORECAST AREA. COOLER TEMPERATURES WILL SPREAD OVER THE AREA
FOR THE END OF THE WEEK. IMMEDIATELY BEHIND THE COLD FRONT HIGHS
WEDNESDAY WILL BE IN THE 80S. BY FRIDAY HIGHS IN THE 70S ARE
EXPECTED. OVERNIGHT LOWS SHOULD COOL INTO THE 50S BY FRIDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1257 PM CDT SAT SEP 7 2013
SURFACE LOW...UPPER LEVEL DISTURBANCE AND APPROACHING COLD FRONT
TO COMBINE FOR AT LEAST SCATTERED SHOWERS AND STORMS BY LATE AFTN
THROUGH THIS EVE. BRIEF IFR TO MVFR VSBYS POSSIBLE WITH THE
STRONGER SHOWERS AND ANY STORMS. OVRNGT INTO SUN AM SOME OF THE
MODEL GUIDANCE SUPPORTIVE OF STRATUS AND FOG WITH IFR TO MVFR
CONDITIONS DEVELOPING WITH COOLER NORTHEASTERLY FLOW AND RESIDUAL
LOW LEVEL MOISTURE. WINDS THIS AFTERNOON WILL BE MAINLY FROM THE
SOUTHWEST 5-10 KTS WITH SOME LOCALIZED GUSTS NEAR 18 KTS. THIS
EVE FOR A TIME WINDS WILL BE LIGHT AND VARIABLE BEFORE SHIFTING TO
NORTH WITH FRONTAL PASSAGE AND EVENTUALLY BECOMING E/NE BY 12Z SUN.
SOME GUSTS OF 15-20 KTS POSSIBLE SUN AM.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...DLF
AVIATION...05
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
403 PM EDT SAT SEP 7 2013
.SHORT TERM...THIS EVENING TONIGHT
DIRECT CYCLONIC VORTICITY ADVECTION WAS EFFICIENT ENOUGH TO ALLOW
WIDESPREAD PRECIPITATION TO FALL OUT OF A MIDCLOUD DECK 8-10KFT
AGL...THROUGHOUT MUCH IF NOT ALL OF SOUTHEASTERN MICHIGAN EARLIER
THIS AFTERNOON. A DRY ATMOSPHERE BELOW 8000FT AGL...COMPOUNDED TO
THE FORECAST DIFFICULTY.
THE QUESTION REMAINS WHAT SORT OF RECOVERY CAN HAPPEN HERE ON AN
EARLY SEPTEMBER AFTERNOON WITH OPAQUE CLOUDS ABOVE...AND A
EVAPORATIVE/RAIN COOLED NEAR SURFACE LAYER BELOW. SURFACE
OBSERVATIONS ARE SHOWING SOME LOW 80S CREEPING INTO WESTERN LOWER
MICHIGAN AND SOME BREAKS IN THE CLOUDS EAST OF THE ANVIL OVER FAR
SOUTHEASTERN WISCONSIN. THE LEGITIMATE COLD FRONT IS CURRENTLY UP
OVER PORTIONS OF NORTHERN LAKE HURON...NORTH OF ROGERS CITY AND
PRESQUE ISLE. GIVEN THE BREAKS WITH UNIFORM SOUTHWESTERLY FLOW STILL
EXPECT TEMPERATURES TO CLIMB ABOVE 80 DEGREES. RAP BASED SPC
MESOANALYSIS DOES SHOW SOME OF THIS RECOVERY WITH MLCAPES AT/AROUND
1000 J/KG INVOF MIDLAND COUNTY THUNDERSTORM. THEREFORE...MUCH OF THE
INFORMATION PROVIDED IN THE MORNING UPDATE DISCUSSION REMAINS VALID.
NEW INFORMATION IS THE MIDLAND THUNDERSTORM/CELL THAT IS SHOWING
ORGANIZATION WITH SOME FORWARD LEAN AND DECENT MIDLEVEL CONVERGENCE.
THEREFORE...THUNDERSTORMS ARE STILL EXPECTED TO POSE AN ISOLATED
RISK OF STRONG WINDS. BETTER POTENTIAL REMAINS OVER THE NORTHERN CWA
20-01Z...A BRIEF WINDOW ACROSS THE SOUTHERN CWA 00-03Z.
THE COLD FRONT SHOULD PUSH STEADILY THROUGH THE CWA FROM NORTH TO
SOUTH BETWEEN 03-12Z. LOW STRATUS ALREADY EXISTS NORTH OF LAKE
HURON/GEORGIAN BAY AND MAY BE SHOWING A PRECURSOR TO TOMORROW
MORNING...WHERE AT LEAST A FRACTION OF THE NWP IS SHOWING A LOW
STRATUS BLANKET 12Z.
&&
.LONG TERM...SUNDAY THROUGH NEXT SATURDAY
COLD FRONT WILL HAVE CLEARED THE STATE LINE BY SUNDAY MORNING
LEAVING HIGH PRESSURE TO BUILD IN DURING THE DAY. CONSIDERATION OF
MOISTURE FLUX OFF LAKE HURON IN COMBINATION WITH FORECAST SOUNDINGS
CONTINUE TO SUPPORT THE IDEA OF MOSTLY CLOUDY SKIES TO START THE DAY
ACROSS SOUTHEAST MICHIGAN...AS MOISTURE LOCKS IN UNDER AND
INVERSION. MUCH DRIER AIR SHOULD START TO ARRIVE FROM CANADA DURING
THE AFTERNOON...AND SHOULD ERODE THE CLOUD DECK AS IT MIXES DOWN TO
THE SURFACE. DRIZZLE COULD BE A POSSIBILITY IF THE LOW LEVELS BECOME
SATURATED ENOUGH UNDER THE DRIER AIR ARRIVING ABOVE THE
INVERSION...ALTHOUGH IT IS NOT MENTIONED IN THE FORECAST AT THIS
TIME. CURRENT FORECAST SOUNDINGS DO NOT LOOK SATURATED ENOUGH TO
JUSTIFY A MENTION...HOWEVER CAN SEE POTENTIAL FOR MODELS TO
UNDERPLAY MOISTURE OFF LAKE HURON IN THE LOWER LEVELS. THIS WILL BE
A SHORTER-TERM FORECAST CONCERN. THE COMBINATION OF COLD AIR
ADVECTION AND NORTHEAST FLOW OFF THE LAKES WILL KEEP TEMPERATURES
COOL TOMORROW...ONLY REACHING INTO THE 60S ACROSS THE THUMB AND NEAR
THE LAKESHORES...AND IN THE LOW/MID 70S FURTHER INLAND.
UPPER LOW OVER BRITISH COLUMBIA AND WASHINGTON STATE WILL TRACK
EAST...OPENING AND MOVING INTO UPPER MIDWEST/SOUTHERN CANADA BY
MONDAY NIGHT. SURFACE LOW PRESSURE WILL BECOME ORGANIZED OVER THE
NORTHERN PLAINS AND MIDWEST ON MONDAY...WHICH WILL ALLOW A WARM
FRONT TO LIFT ACROSS MICHIGAN. MODELS ARE NOW SHOWING A GOOD PUSH OF
THETA-E ADVECTION AND A BAND OF GOOD SYSTEM RELATIVE ISENTROPIC
ASCENT AS A WARM FRONT AND LOW-LEVEL JET LIFT THROUGH DURING THE
LATE MORNING AND AFTERNOON. THIS MAY BE ENOUGH FORCING TO ALLOW A
BAND OF SHOWERS/TSTORMS TO MOVE THROUGH BEFORE WE BECOME ENTRENCHED
IN A MORE STABLE WARM SECTOR.
IMPRESSIVE WARM AIR ADVECTION LOOKS TO OCCUR LATE MONDAY THROUGH
TUESDAY AS THE LOW MOVES INTO THE NORTHERN GREAT LAKES AND STRONG
SOUTH TO SOUTHWEST FLOW CONTINUES TO PUMP WARMER AIR INTO THE AREA.
FORECAST SOUNDINGS LOOK EXTREMELY CAPPED PRIOR TO 18Z...UNTIL DEEPER
MIXING STARTS TO CHIP AWAY AT THE INVERSION. LOOKS LIKE ENOUGH OF AN
INVERSION WILL HOLD TO KEEP A DRY FORECAST...IN ADDITION TO THE COLD
FRONT REMAINING UPSTREAM DURING THE DAY. TUESDAY LOOKS BREEZY AND
HOT AS H850 TEMPERATURES RISE TO 20-22C AND ENOUGH MIXING LOOKS
PRESENT TO REALIZE ALL THE WARMING ALOFT. SOME SUNSHINE SHOULD HELP
BOOST TEMPERATURES INTO THE LOW OR EVEN MID 90S. BREEZY
CONDITIONS...POSSIBLY EVEN WINDY...ALSO LOOK LIKELY WITH GFS/NAM
SOUNDINGS SHOWING A SOLID CORE OF 20 KNOTS EVEN AT THE VERY BOTTOM
OF THE MIXED LAYER...WITH HIGHER SPEEDS EVEN FURTHER UP. BIGGEST
CONCERN FOR THIS DAY WILL ACTUALLY BE FOR FIRE WEATHER INTERESTS
WITH HOT AND BREEZY CONDITIONS. DEWPOINTS LOOK TO SETTLE INTO THE
MID 60S (PER GFS SOUNDINGS) BUT COULD GO LOWER IF DRIER NAM
VERIFIES. THIS SHOULD KEEP MIN RELATIVE HUMIDITIES ABOVE 30 PERCENT.
WILL WATCH TRENDS HOWEVER.
COLD FRONT WILL DROP THROUGH TUESDAY EVENING THROUGH WEDNESDAY
MORNING...WITH LOW-LEVEL FORCING AIDED BY RIGHT ENTRANCE REGION
FORCING ALOFT. THIS SHOULD PROVIDE AT LEAST A SCATTERED COVERAGE OF
SHOWERS/TSTORMS ACROSS THE AREA AS THE FRONT DROPS THROUGH.
UPPER TROUGHING WILL SET UP OVER THE GREAT LAKES WEDNESDAY THROUGH
THURSDAY...WITH UPPER SHORTWAVES ROTATING THROUGH THE MAIN TROUGH
SENDING REINFORCING SHOTS OF COLD AIR DOWN INTO THE GREAT LAKES.
THIS SHOULD DROP TEMPERATURES BACK DOWN TO BELOW NORMAL FOR THE END
OF THE WEEK...EVEN AS HIGH PRESSURE BUILDS BACK IN ON FRIDAY.
&&
.MARINE...
THE PASSAGE OF A COLD FRONT TONIGHT WILL USHER IN A SOLID 12 HOUR
PERIOD OF STRONG NORTH NORTHEAST WINDS THAT WILL GUST TO NEAR GALES
ACROSS THE OPEN WATERS OF CENTRAL LAKE HURON AND POSSIBLY OUTER
SAGINAW BAY AND THE EXPOSED NEARSHORE WATERS OF THE THUMB.
LIKEWISE...THESE SAME LOCATIONS WILL SEE SIGNIFICANT WAVE HEIGHTS
BUILD INTO THE 6 TO 8 FOOT RANGE DURING THIS TIME PERIOD WITH THE
REMAINING NEARSHORE ZONES GENERALLY EXPERIENCING SIG WAVES OF 6 FEET
OR LESS. WINDS WILL EASE BY SUNDAY EVENING FOLLOWED BY SUBSIDING
WAVES BY LATE SUNDAY NIGHT. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED
ACCORDINGLY FOR ALL NEARSHORE ZONES OF LAKE HURON. A REDUCED FETCH
FOR THE SOUTHERN WATERS OF LAKE SAINT CLAIR AND MICHIGAN WATERS OF
LAKE ERIE WILL LIMIT THEIR SIG WAVES TO AROUND 3 FEET.
&&
.AVIATION...ISSUED 144 PM EDT SAT SEP 7 2013
//DISCUSSION...
TWO TIME WINDOWS FOR PRECIPITATION THIS AFTERNOON. THE FIRST IS WITH
ONGOING SHOWER ACTIVITY WITH VFR CEILINGS AND A MID CLOUD DECK. THIS
ACTIVITY WILL PUSH EASTWARD DURING THE FIRST COUPLE OF HOURS OF THE
TAF PERIOD. THEN POTENTIAL EXISTS FOR THUNDERSTORM DEVELOPMENT AHEAD
OF AN APPROACHING COLD FRONT BOUNDARY. DID GO AGGRESSIVE WITH TIMING
A 3 HOUR TEMPO GROUP FROM NORTH TO SOUTH. THE SUPPORT FOR SHOWER AND
THUNDERSTORMS SHOULD END AT THE SOUTHERN TAF SITES BETWEEN 0-2Z.
FOR DTW...PREVAILING SOUTHWEST FLOW WILL CONTINUE BEFORE A MORE
ABRUPT SHIFT TO THE NORTHEAST TAKES PLACE WITH THE PASSAGE OF THE
SURFACE TROUGH TONIGHT AROUND 04Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE THAT CEILING HEIGHTS WILL LOWER BELOW 5000 FT
AFTER 6Z TONIGHT.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS
FROM PORT AUSTIN TO PORT SANILAC...FROM 2 AM SUNDAY TO 10 PM
SUNDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT SANILAC TO PORT
HURON...FROM 5 AM SUNDAY TO 4 AM MONDAY.
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 5 AM SUNDAY TO 4 PM
SUNDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
MI WATERS OF LAKE ERIE...
SMALL CRAFT ADVISORY...FROM 8 AM SUNDAY TO 8 PM SUNDAY.
&&
$$
SHORT TERM...CB
LONG TERM....HLO
MARINE.......CB
AVIATION.....CB
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
140 PM EDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1057 AM EDT SAT SEP 7 2013
TRICKY FORECAST FOR THE REST OF TODAY...AS THE COLD FRONT CONTINUES
TO SLIDE SOUTH ACROSS THE SOUTHEAST PART OF UPPER MICHIGAN. THE
THUNDERSTORMS ASSOCIATED WITH THIS FRONT HAVE NEARLY LEFT CWA IN
LAKE MICHIGAN. OTHER THAN A FEW SHOWERS REDEVELOPING OVER
DICKINSON/MENOMINEE COUNTIES THIS AFTERNOON...THE SHOWERS
ASSOCIATED WITH THE FRONT SHOULD BE DONE.
ATTENTION THEN TURNS TO THE CLOUDINESS OVER LAKE SUPERIOR. VISIBLE
SATELLITE SHOWS TWO CLOUD DECKS...WITH MID CLOUDS SHIFTING
EAST-SOUTHEAST AND A LOW STRATUS DECK DROPPING SOUTH TO
SOUTH-SOUTHWEST. THERE WAS SOME UNCERTAINTY ON IF THE CLOUDS WERE
FOG OR LOW STRATUS...AS WEBCAMS ALONG LAKE SUPERIOR IN THE KEWEENAW
AND EAST WEREN/T POINTING ONE WAY OR ANOTHER. BUT THE 1435Z OB FROM
KCMX HAS INDICATED IT IS MORE OF A LOW STRATUS WITH SOME FOG OR
DRIZZLE. THUS...WILL ADJUST THE FORECAST FOR LOCATIONS NEAR LAKE
SUPERIOR FOR MORE CLOUDINESS THIS AFTERNOON UNDER THE
NORTH-NORTHEAST WINDS. BASED OFF THE THICKNESS OF THE LOW CLOUDS ON
THE LATEST RAP RUNS...WILL ADD A MENTION OF DRIZZLE TO THE HIGHER
TERRAIN OF NORTH CENTRAL AND THE KEWEENAW DURING THE AFTERNOON.
THIS COOL FLOW OFF LAKE SUPERIOR WILL ALSO LEAD TO TEMPERATURES
FALLING THROUGH THE AFTERNOON FROM THE CURRENT VALUES IN THE LOWER
70S AND INTO THE MID-LOWER 60S TOWARDS EVENING. UPDATED GRIDS WILL
BE OUT SHORTLY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 519 AM EDT SAT SEP 7 2013
GENERALLY DECAYING SHOWERS AND THUNDERSTORMS HAVE BEEN THE
RULE...AND DESPITE ALL THE MOISTURE AROUND FOG HAS BEEN SLOW TO
MATERIALIZE ANYWHERE THAT HAD LESS THAN 0.25IN OF RAIN OVER THE PAST
24 HOURS. FOG OVER W AND E LAKE SUPERIOR TO PUSH S BEHIND THE COLD
FRONT SET UP FROM NW WI THROUGH THE KEWEENAW AND NE LAKE SUPERIOR.
THIS BOUNDARY WILL BE ENOUGH TO SPARK THE POTENTIAL OF ADDITIONAL
SHOWERS AND THUNDERSTORMS OVER MAINLY CENTRAL AND E UPPER MI LATE
THIS MORNING AND EARLY THIS AFTERNOON...BEFORE SIGNIFICANTLY
COOLER/DRIER AIR WORKS IN. MODEL TIMING ON THE COLD FRONT IS
REASONABLE...SLIPPING TO FAR S CENTRAL PORTIONS OF THE CWA BY 18Z.
EXPECT SLOWLY FALLING TEMPS THIS AFTERNOON OVER THE N AS A
RESULT...AS CLOUD COVER BEGINS TO DIMINISH. KEPT WITH THE COOL TEMPS
TONIGHT ON NNE FLOW AND 850MB TEMPS FALLING TO A CWA AVG 9C. PW
VALUES SHOULD FALL FROM AROUND 150 PERCENT OF NORMAL /1.5IN/ THIS
MORNING TO A 40-50 PERCENT OF NORMAL BY 12Z SUNDAY /0.35-0.4IN/.
LOWERED THE TRADITIONAL COOL SPOTS A BIT MORE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 505 AM EDT SAT SEP 7 2013
IN THE LONG TERM...PATTERN IN THE MEAN WILL CONTINUE TO FEATURE A NW
CANADA RIDGE AND ERN N AMERICA TROF. THIS WILL RESULT IN SHORTWAVES
PERIODICALLY DROPPING SE FROM THE NW RIDGE INTO THE ERN TROF. TWO
MORE SIGNIFICANT WAVES WILL BRING NOTABLE AMPLIFICATION OF THE ERN
TROF. THE FIRST WILL BE THIS WEEKEND AND THE SECOND WILL BE LATE IN
THE UPCOMING WEEK. THE SECOND AMPLIFICATION LOOKS LIKE IT WILL BRING
THE COOLEST AIR TO THE UPPER LAKES...POSSIBLY POSING A RISK OF THE
FIRST WIDESPREAD FROST OF THE SEASON LATE WEEK. BTWN THE 2 SURGES OF
COOL AIR...TEMPS WILL BE AT OR ABOVE NORMAL. UNDERNEATH THE LARGER
SCALE RIDGE/TROF PATTERN...MID LEVEL LOW CURRENTLY OVER ERN WA WILL
OPEN UP AND SHIFT GENERALLY E ROUGHLY ALONG THE U.S./CANADA
BORDER...AFFECTING THE UPPER LAKES MON/TUE. THIS SYSTEM SHOULD BRING
THE BEST CHANCE OF PCPN DURING THE LONG TERM PORTION OF THE FCST.
FARTHER DOWN THE ROAD...GUIDANCE SUGGESTS THE NW CANADA RIDGE WILL
BE REPLACED BY A TROF...RESULTING IN DOWNSTREAM HEIGHT RISES ACROSS
THE CNTRL CONUS. SO...A WARM PERIOD MAY BE SHAPING UP BEYOND THIS 7
DAY FCST.
BEGINNING SUN...ON THE BACKSIDE OF THE AMPLIFYING ERN TROF...
CANADIAN HIGH PRES WILL SETTLE SE OVER THE UPPER GREAT LAKES. ONLY
FCST CONCERN CONTINUES TO BE THE POTENTIAL FOR SOME MORNING LOW
CLOUDS OFF LAKE SUPERIOR IN UPSLOPE N/NE FLOW. THE NAM IS COOLEST IN
BRINGING 850-875MB TEMPS DOWN TO AROUND 5C ACROSS LAKE SUPERIOR AT
12Z SUN. OTHER GUIDANCE IS AROUND 2C WARMER. IF THE COOLER NAM IS
CORRECT...WATER TEMPS AS HIGH AS 16-18C OVER SRN LAKE SUPERIOR WILL
BE SUFFICIENT FOR STRATOCU OFF THE LAKE. SINCE LOW CLOUDS ARE
EVIDENT OVER HUDSON BAY INTO ADJACENT NRN MANITOBA/NRN ONTARIO AND
SINCE WIND FLOW AHEAD OF HIGH MAY TEND TO ADVECT SOME OF THIS
SHALLOW MOISTURE INTO THE AREA...OPTED TO RETAIN SOME CLOUD COVER
SUN MORNING NEAR LAKE SUPERIOR EVEN IN FAVORING GUIDANCE WARMER THAN
THE NAM. UPSLOPE CLOUDS SHOULDN`T STICK AROUND LONG UNDER
INCREASINGLY ANTICYCLONIC LOW-LEVEL FLOW...ADVECTION OF DRIER AIR
AND DAYTIME HEATING. FARTHER INLAND...MAY SEE A BLOSSOM OF SCT TO
PERHAPS BKN CU/STRATOCU FOR JUST A BRIEF TIME BEFORE DAYTIME HEATING
MIXES OUT LOW-LEVEL MOISTURE. THE AFTN HRS SHOULD FEATURE ABUNDANT
SUNSHINE ACROSS THE BOARD. TEMPS WILL BE ON THE COOL SIDE OF NORMAL
DESPITE THE SUNSHINE. MIXING TO THE INVERSION BASE ON FCST SOUNDINGS
YIELDS HIGH TEMPS NEAR 70 AWAY FROM THE MODERATING INFLUENCE OF THE
GREAT LAKES.
SUN NIGHT...MIDLEVEL LOW CURRENTLY OVER ERN WA WILL HAVE OPENED UP
AND WILL REACH SRN SASKATCHEWAN/ERN MT BY 12Z MON. IN RESPONSE...
DEVELOPING LOW-LEVEL JET WILL SHIFT ACROSS THE DAKOTAS INTO MN
DURING THE NIGHT. THE ECMWF CONTINUES TO BE THE FASTEST SPREADING
PCPN INTO UPPER MI SUN NIGHT IN ASSOCIATION WITH A LEAD MINOR
SHORTWAVE MOVING INTO THE UPPER LAKES. THE UKMET HAS NOW FOLLOWED
SUIT. THE GFS HAS PCPN REACHING THE FAR W OVERNIGHT. MEANWHILE...THE
NAM/GEM MAINTAIN STRONGER SFC HIGH PRES RIDGING BACK INTO THE UPPER
LAKES AND THUS KEEP PCPN W OF UPPER MI THRU 12Z MON. FOR NOW...PLAN
TO MAINTAIN CONTINUITY WITH THE LAST FEW FCST CYCLES AND WILL ONLY
BRING SCHC POPS INTO THE FAR W OVERNIGHT...SIMILAR TO THE GFS WHICH
REPRESENTS A GOOD COMPROMISE BTWN THE ECMWF/UKMET AND GEM/NAM.
OTHERWISE...SOUTHERLY RETURN FLOW OF WARMER/MOISTER AIR AND AN
INCREASE IN CLOUDS WILL RESULT IN A WARMER NIGHT MOST AREAS...
ESPECIALLY OVER THE W WHERE GRADIENT WILL BE TIGHTENING FIRST AND
WHERE CLOUDS WILL ARRIVE EARLIEST. LINGERING DRY AIR MASS IN THE
EVENING COMBINED WITH INITIALLY CLEAR SKIES AND LIGHT/CALM WIND OVER
THE E MAY ALLOW TEMPS AT TRADITIONAL INTERIOR COLD SPOTS TO FALL
INTO THE LWR 40S.
MON/TUE...MAIN SHORTWAVE WILL CONTINUE TO TRACK E...PASSING ACROSS
THE UPPER LAKES MON NIGHT/TUE. WHILE TIMING OF FEATURE HAS
IMPROVED...TRACK OF ASSOCIATED SFC LOW REMAINS MORE UNCERTAIN.
THE ECMWF HAS TRENDED S AND HAS SFC LOW TRACKING ACROSS UPPER MI...
NOT TOO DIFFERENT FROM THE NAM. ONLY SCNTRL AND ERN UPPER MI MAY
SLIP INTO THE WARM SECTOR MON NIGHT. END RESULT WOULD PROBABLY BE
FAIRLY WIDESPREAD SHRA/TSRA ACTIVITY ACROSS THE FCST AREA MON...
ESPECIALLY NRN PORTIONS. THE GFS/GEM ARE FARTHER N (GEM HAS BEEN ALL
ALONG) AND HAVE SFC LOW TRACKING OVER OR JUST N OF LAKE SUPERIOR.
RESULT WOULD BE SHRA/TSRA ACTIVITY N OF WARM FRONT BEING SHIFTED
FARTHER N...PERHAPS MOSTLY N OF UPPER MI MON/MON NIGHT. WITH THE
ECMWF NORMALLY PROVIDING BETTER GUIDANCE AND WITH 2 CONSECUTIVE RUNS
NOW SHOWING THE FARTHER S TRACK...HEDGED FCST SLIGHTLY IN THAT
DIRECTION WHICH RESULTED IN INCREASING POPS/QPF A BIT ACROSS THE N
MON/MON NIGHT. EFFECTIVE SHEAR MON LOOKS BE ON THE ORDER OF
30-40KT...SUPPORTING THE POTENTIAL OF STRONG TO SVR STORMS...BUT
MUCH WILL DEPEND ON THE MAGNITUDE OF INFLOW INSTABILITY FOR THE
ELEVATED STORMS. EVEN THE GFS WITH ITS FARTHER N SFC LOW TRACK IS
SLOW TO BRING SUFFICIENT INSTABILITY N FOR STRONG/SVR STORMS MON.
BETTER POTENTIAL OF SVR STORMS SHOULD BE MON NIGHT AS INSTABILITY
AXIS SHIFTS INTO THE UPPER LAKES. HOWEVER...IF WARM FRONT LIFTS N OF
THE AREA...EXPECTED ARRIVAL OF COLD FRONT LATE NIGHT INTO TUE
MORNING WOULD BE MORE IN SYNC WITH DIURNAL MIN...SUGGESTING A
DIMINISHED SVR THREAT. IF WARM FRONT ONLY LIFTS INTO UPPER MI...THEN
THERE WOULD BE THE POTENTIAL FOR ELEVATED SVR STORMS N OF FRONT MON
NIGHT. AT LEAST WITH SHORTWAVE RAPIDLY WEAKENING AS IT MOVES ACROSS
THE UPPER LAKES...THERE DOES NOT APPEAR TO BE A POTENTIAL FOR
WIDESPREAD SVR STORMS. LATEST SPC OUTLOOK ONLY HAS PORTIONS OF UPPER
MI IN A 5 PCT RISK WHICH APPEARS REASONABLE AT THIS TIME. ON TUE...
SHRA/TSRA CHANCES SHOULD BE MOSTLY CONFINED TO THE ERN FCST AREA AS
SFC LOW/COLD FRONT WILL STILL NEED TO PASS THRU THAT AREA.
HEADING INTO WED/THU...THE ECMWF HAS CONTINUED TO BACK OFF ON ITS
FARTHER W AND MUCH MORE SHARPLY DIGGING SHORTWAVE INTO THE UPPER
MISSISSIPPI VALLEY AND GREAT LAKES. NOW...MEDIUM RANGE GUIDANCE IS
GENERALLY WELL CLUSTERED WITH THE TROF AMPLIFICATION OCCURRING THRU
THE GREAT LAKES AND THEN INTO NEW ENGLAND LATE WEEK. WITH MUCH OF
THE DEEP MOISTURE SWEPT OUT OF THE AREA BY THE PRIOR SHORTWAVE...
NOTHING MORE THAN LOW CHC POPS APPEAR WARRANTED WED AS COLD FRONT
DROPS THRU THE UPPER LAKES. SHRA CHANCES MAY LINGER THRU THU WITH
HINTS OF ANOTHER WAVE DROPPING ACROSS THE AREA INTO THE AMPLIFYING
TROF. THU WILL FEEL LIKE AUTUMN AS COOL AIR MASS DUMPS INTO THE
UPPER LAKES ON BREEZY NW WINDS. IT`S POSSIBLE MAX TEMPS MAY ONLY BE
IN THE 50S OVER MUCH OF THE FCST AREA THU IF ANOTHER SHORTWAVE DOES
DROP INTO THE UPPER LAKES...RESULTING IN MOSTLY CLOUDY SKIES AND SCT
SHRA. IT APPEARS SFC HIGH WILL SETTLE INTO THE AREA THU NIGHT PER
CONSENSUS OF MEDIUM RANGE GUIDANCE. IF SO AND IF STRATOCU CLEARS
OUT...THERE WILL BE A WIDESPREAD FROST IN THE INTERIOR...ESPECIALLY
OVER THE W WHICH WILL BE CLOSER TO ARRIVING SFC HIGH PRES CENTER.
WITH SFC HIGH PRES LINGERING OVER THE AREA FRI...EXPECT A SUNNY BUT
COOL DAY...THOUGH NOT AS COOL AS THU. SOME FROST COULD OCCUR AGAIN
FRI NIGHT...THOUGH THIS TIME MORE LIKELY OVER THE E...CLOSER TO
DEPARTING SFC HIGH. WARMING TREND WILL BE UNDERWAY SAT UNDER
CONTINUED RETURN FLOW AS HIGH PRES MOVES TO THE E COAST. HIGH TEMPS
SAT SHOULD BE CLOSER TO NORMAL.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 140 PM EDT SAT SEP 7 2013
LOW STRATUS AND FOG MOVED INTO ALL THREE TAF SITES OVER THE LAST
FEW HOURS. THIS IS DUE TO THE NORTHERLY FLOW BEHIND THE COLD FRONT
THAT MOVED THROUGH LAST NIGHT AND PUSHED THE LOW CLOUDS SOUTH
OFF LAKE SUPERIOR. EXPECT THESE CONDITIONS TO CONTINUE THROUGH MUCH
OF THE AFTERNOON...BUT DRIER AIR ASSOCIATED WITH HIGH PRESSURE NEAR
LAKE WINNIPEG HAS ALREADY BEEN SEEN ON VISIBLE SATELLITE SLIDING
SOUTH OVER NORTHERN LAKE SUPERIOR. IN ADDITION...THE
CEILINGS/VISIBILITIES HAVE ALREADY STARTED TO MOVE UPWARD AT KCMX
AND BASED OFF WEBCAMS IN THE KEWEENAW. THUS...SHOULD HAVE CONDITIONS
HEADING TO VFR FROM NORTH TO SOUTH BY LATE AFTERNOON INTO EARLY
EVENING. THIS DRY AIR WILL LEAD TO CLEAR SKIES AND WEAKENING WINDS
THROUGH THE REST OF THE TAF PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 519 AM EDT SAT SEP 7 2013
A TROUGH WILL CONTINUE TO SINK SOUTH ACROSS THE UPPER GREAT LAKES
TODAY. BEHIND THE TROUGH...HIGH PRESSURE WILL BE ABLE TO SLIDE
IN...CROSSING LAKE SUPERIOR SUNDAY...BEFORE PUSHING ACROSS THE LOWER
GREAT LAKES SUNDAY NIGHT. ANY FOG THAT DEVELOPS WILL LIKELY SINK
SOUTH TODAY/TONIGHT AS DRIER AIR WORKS IN FROM THE N. A FEW GUSTS
NEAR 25KTS WILL BE POSSIBLE LATE TONIGHT THROUGH EARLY SUNDAY. LOW
PRESSURE ACROSS THE NORTHERN AND CENTRAL PLAINS SUNDAY NIGHT WILL
EDGE ACROSS THE UPPER GREAT LAKES MONDAY NIGHT INTO TUESDAY. A BRIEF
RIDGE WILL FILTER IN TUESDAY NIGHT...OUT AHEAD OF A CENTRAL CANADIAN
LOW MOVING OVER HUDSON BAY ON WEDNESDAY. THIS LOW WILL BRING A
TROUGH TO LAKE SUPERIOR WEDNESDAY AFTERNOON AND EVENING.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...SRF
SHORT TERM...KF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...KF
AREA FORECAST DISCUSSION
NWS BILLINGS MT
306 PM MDT SAT SEP 7 2013
.SHORT TERM...VALID FOR SUN AND MON...
INGREDIENTS ARE IN PLACE ACROSS THE REGION FOR A BUSY AFTERNOON
AND NIGHT. UPPER TROUGH OVER WASHINGTON STATE SLOWLY MOVING
EASTWARD. LOW LEVEL JET OVER EAST HAS BROUGHT UP AN ABUNDANT
AMOUNT OF MOISTURE ACROSS THE EASTERN SECTIONS OF MONTANA AND
NEARBY AREAS. MONSOONAL MOISTURE IS EXPECTED TO STREAM ACROSS THIS
SAME AREA. PRECIPITABLE WATER LEVELS UP AROUND 1.50 INCHES...WHICH
IS HIGHLY UNUSUAL FOR THIS TIME OF YEAR...WILL LIKELY LEAD TO
THUNDERSTORMS WITH VERY HEAVY RAINFALL. WE HAVE ALSO SEEN SOME
TRAINING CELLS OVER CUSTER COUNTY ALREADY TODAY. THUS...THE FLASH
FLOOD WATCH WILL REMAIN IN PLACE THROUGH 6AM. THE HRRR MODEL
DEVELOPS TWO WAVES OF CONVECTIVE ACTIVITY...PRIMARILY HITTING
AREAS FROM BIG HORN COUNTY NORTH AND EAST...AND THE LAST WAVE
CARRIES WELL INTO THE NIGHT OUT EAST.
DUE TO INSTABILITY FACTORS AND SHEAR PROFILES...WE COULD ALSO SEE
SOME HAIL AND DAMAGING WIND...THOUGH AT THIS TIME I FEEL
TORRENTIAL RAINFALL IS MORE OF A THREAT. THE SHEAR PROFILE AND
OVERALL PATTERN DOES ALSO SUPPORT THE SLIGHT CHANCE OF AN ISOLATED
TORNADO IN THE EASTERN COUNTIES...THOUGH WOULD LIKE TO SEE SHEAR
JUST A BIT STRONGER...LESS INITIAL CLOUD COVER AND GREATER
INSTABILITY. NEVERTHELESS...WE WILL BE MONITORING STORMS CLOSELY
FOR DEEP ROTATION...ESPECIALLY FROM MILES CITY TO BROADUS
EASTWARD.
AS STORMS DIMINISH IN THE EAST LATE TONIGHT...UPPER TROUGH BEGINS
TO SWING THROUGH NORTH/CENTRAL MONTANA IN THE MORNING. BEST
MOISTURE AND SHEAR PROFILES WILL BE LOCATED FURTHER EAST...BUT
LIFT WILL BE MUCH GREATER ACROSS THE REGION WITH GOOD Q VECTOR
FORCING. HEAVY RAIN IS STILL A GOOD BET TOMORROW WITH SOME
STORMS...AND MAYBE LOTS OF SMALL HAIL OR GROUPEL. BT
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
SEASONABLY WARM WEATHER IS EXPECTED NEXT WEEK...WITH AN INCREASING
CHANCE OF CONVECTION BY FRI AND SAT WHEN THE 12 UTC GUIDANCE SHOWS
ANOTHER SURGE OF MONSOONAL MOISTURE ARRIVING. AN AMPLIFIED 500-HPA
RIDGE WILL BECOME ESTABLISHED ACROSS THE REGION ONCE AGAIN BY MID-
WEEK WITH ABOVE-NORMAL HEIGHTS FOR THIS TIME OF THE YEAR. ITS AXIS
APPEARS ORIENTED MORE NORTHWEST-SOUTHEAST THAN LAST WEEK/S VERSION
OF A LATE-SEASON RIDGE THOUGH...WHICH WILL LIKELY HELP MAINTAIN AN
EASTERLY LOW-LEVEL FLOW AND A SOMEWHAT COOLER AIR MASS IN SOUTHERN
MT AND NORTHERN WY THAN WHAT WE HAVE EXPERIENCED RECENTLY. BY LATE
IN THE WEEK...GUIDANCE SUGGESTS SHORT WAVE ENERGY WILL LIFT ACROSS
THE AREA AND LOWER THE 500-HPA HEIGHTS AS PRECIPITABLE WATER AGAIN
RISES ABOVE AN INCH. THE RESULT SHOULD BE AT LEAST ISOLATED SHOWER
AND STORM ACTIVITY...AND INCREASING CLOUDS TO HOLD BACK HIGHS SOME
MORE. IF TRENDS IN THE 12 UTC GUIDANCE HOLD TRUE WITH LATER CYCLES
THEN WE MAY NEED TO LOWER HIGHS A BIT THROUGH THE PERIOD AND RAISE
POPS A BIT BY FRI AND SAT. SCHULTZ
&&
.AVIATION...
THUNDERSTORMS WILL AFFECT THE AREA THROUGH THIS EVENING...WITH THE
HIGHEST PROBABILITIES OF STORMS FROM AROUND KSHR TO KMLS AND KBHK.
IFR OR POSSIBLY EVEN LIFR CONDITIONS IN HEAVY RAIN ARE EXPECTED IN
THE MOST INTENSE STORMS...WITH A THREAT OF LARGE HAIL AND DAMAGING
WINDS TOO. THE ACTIVITY SHOULD SLOWLY DIMINISH BY LATE NIGHT...BUT
LOW CEILINGS MIGHT FORM IN ITS WAKE BY SUNDAY MORNING. SCHULTZ
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 060/081 057/079 054/084 055/085 058/088 060/088 057/088
45/T 50/B 00/U 00/U 00/U 12/T 22/T
LVM 053/080 048/077 046/084 046/085 051/087 052/090 054/090
34/T 31/U 00/U 00/U 02/T 23/T 32/T
HDN 059/083 055/081 052/085 053/087 057/090 058/089 059/090
56/T 51/B 00/U 00/U 00/U 11/U 12/T
MLS 063/082 059/080 055/084 055/085 057/086 060/086 058/088
56/T 62/W 10/U 00/U 00/U 11/U 11/U
4BQ 062/084 058/081 052/084 054/086 057/086 058/086 059/090
65/T 52/W 00/U 00/U 00/U 12/T 22/T
BHK 061/081 057/077 053/080 054/081 054/080 056/081 055/081
76/T 72/T 11/U 10/U 00/U 11/U 12/T
SHR 058/082 053/077 047/083 050/085 053/089 055/087 053/087
45/T 42/W 00/U 00/U 00/U 12/T 22/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
29>33-35>38-57-58.
WY...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT FOR ZONES
98-99.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
143 PM EDT SAT SEP 7 2013
.SYNOPSIS...
HIGH PRESSURE WILL GIVEWAY TO AN APPROACHING COLD FRONT WHICH WILL
DROP ACROSS THE REGION TONIGHT. A FEW SHOWERS WILL SPREAD OUT AHEAD
OF THE FRONT THIS AFTERNOON...WITH ANOTHER ROUND TONIGHT WITH THE
FRONT. BRIEFLY COOLER AIR WILL THEN FOLLOW SUNDAY...BUT TEMPERATURES
WILL WARM NEXT WEEK...WITH A RETURN TO MID-SUMMER HEAT ON TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RADAR IMAGERY EARLY THIS AFTERNOON SHOWING A LARGE AREA OF SHOWERS
FROM SOUTHERN ONTARIO EAST ACROSS THE NIAGARA FRONTIER INTO CENTRAL
NY. THIS WILL CONTINUE TO DRIFT SLOWLY ESE ACROSS THE AREA THIS
AFTERNOON WITH OCCASIONAL SHOWERS. THE SOUTHERN TIER WILL ESCAPE
MUCH OF THIS THROUGH LATE AFTERNOON...ESPECIALLY CLOSER TO THE PA
STATE LINE. THE SAINT LAWRENCE VALLEY WILL ALSO HAVE PLENTY OF DRY
TIME WITH JUST A FEW BRIEF SHOWERS.
WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS SEVERAL MID LEVEL
SHORTWAVES MOVING THROUGH THE MEAN NORTHWEST FLOW ALOFT...WITH A
SUPPORTING MID LEVEL SPEED MAX NOTED IN OBJECTIVE RUC ANALYSIS FROM
NORTHERN LAKE HURON TO LAKE ONTARIO. THESE FEATURES ARE AIDING IN
LARGE SCALE ASCENT AND CONVERGENCE. SEASONABLY STRONG LOW/MID LEVEL
WARM ADVECTION AND ISENTROPIC UPGLIDE ARE ALSO FOUND TO THE
NORTHEAST OF A WARM FRONT ANALYZED NEAR LAKE HURON AT 12Z...AND IS
LIKELY PROVIDING THE NECESSARY CONCENTRATED ASCENT TO SUPPORT THE
AREA OF STEADY RAIN OVER LAKE ONTARIO.
WITH THICK CLOUD AND AN EARLIER ARRIVAL OF SHOWERS...TEMPERATURES
WILL STRUGGLE AND STAY IN THE MID TO UPPER 60S IN MOST AREAS. THE
ONLY EXCEPTION WILL BE ACROSS THE SOUTHERN TIER WHERE PLENTY OF DRY
TIME WILL STILL BE FOUND...WITH TEMPERATURES REACHING THE MID 70S IN
THE VALLEYS THERE.
A COLD FRONT WILL DROP ACROSS THE REGION TONIGHT...BRINGING ANOTHER
ROUND OF SHOWERS. UNLIKE THE FIRST ROUND...THESE WILL BE GENERATED
FROM LOW LEVEL LIFT...WITH A FAIRLY STRONG MODEL CONSENSUS AMONG THE
NAM/RGEM/SREF/GFS THAT THERE WILL BE SOME MEASURABLE PRECIPITATION.
THERE WILL BE MODEST ELEVATED INSTABILITY...AND BECAUSE OF THIS
THERE MAY BE AN ISOLATED THUNDERSTORM. SHOWERS WILL END FROM N-S AS
THE FRONT DROPS SOUTH OF THE REGION LATE TONIGHT. NAM/GFS BOTH SHOW
SIGNIFICANT LOW MOISTURE BEHIND THE FRONT...WITH STRATUS LIKELY TO
LINGER BEHIND THE FRONT. THE LATE TIMING WILL KEEP THE CORE OF THE
COLDER AIR UPSTREAM...WITH LOWS FORECAST TO BE IN THE UPPER
50S TO LOWER 60S.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
SUNDAY MORNING MODEL CONSENSUS IS TO BRING THE COLD FRONT TO OUR
SOUTH THROUGH PA. WITH THE FRONT TO OUR SOUTH TO START THE
DAY...THERE WILL ONLY BE A SMALL CHANCE FOR A LEFT OVER SHOWER NEAR
THE STATE LINE EARLY. OTHERWISE SUNDAY WILL BE DRY...WITH MOSTLY
SUNNY SKIES EXPANDING ACROSS THE NORTH COUNTRY. A MOIST NORTHERLY
FLOW FOLLOWING THE COLD FRONT WILL HANG CLOUDS TOUGH THROUGH THE DAY
SOUTH OF LAKE ONTARIO. THIS SLOW CLEARING WILL NOT REACH THE
SOUTHERN TIER UNTIL LATE IN THE DAY SUNDAY. THE COLD AIR ADVECTION
ALOFT BEHIND THE FRONT WILL BRING A COOL DAY WITH HIGHS IN THE LOW
TO MID 60S FOR MUCH OF THE REGION.
SUNDAY NIGHT A BROAD AREA OF HIGH PRESSURE AT THE SURFACE WILL SLIDE
SOUTHWARD FROM NEAR LAKE HURON...TO ACROSS WNY THROUGH THE NIGHT.
ALOFT TEMPERATURES AT 850 HPA WILL FALL INTO THE SINGLE
DIGITS...WITH +5 OR +6C SNEAKING INTO THE NORTH COUNTRY BY MONDAY
MORNING. THESE TEMPERATURES ALOFT WILL BE COOL ENOUGH FOR SOME
PATCHES OF LAKE ENHANCED CLOUDINESS SOUTH OF LAKE ONTARIO SUNDAY
NIGHT. HOWEVER WITH THE DRY AIRMASS...DO NOT EXPECT WIDESPREAD LAKE
CLOUDS TO FORM. A FEW LOCATIONS ACROSS THE SOUTHERN TIER AND EAST OF
LAKE ONTARIO MAY GET COLD ENOUGH FOR SOME PATCHY FROST...BUT THE
LATEST GUIDANCE SUGGESTS THAT THE CORE OF THE COOLEST AIR WILL SHIFT
EAST INTO NEW ENGLAND DURING THE SECOND HALF OF THE NIGHT.
MONDAY THE CENTER OF THE SURFACE HIGHS MOVES OFF THE ATLANTIC COAST
MONDAY AND A WARMER SOUTHERLY FLOW WILL SET UP OVER WESTERN AND
CENTRAL NEW YORK. UNDER MOSTLY SUNNY SKIES TEMPERATURES WILL REBOUND
INTO THE LOWER 70S...AFTER A CHILLY START TO THE DAY. LATER IN THE
DAY EXPECT HIGH LEVEL CIRRUS TO BECOME THICKER ACROSS WNY AHEAD OF A
COLD FRONT IN THE WESTERN GREAT LAKES.
ONGOING WARM AIR ADVECTION WILL STRENGTHEN MONDAY NIGHT. THIS WILL
RESULT IN AN INCREASE IN CLOUDS ACROSS OUR AREA AND AS MOISTURE IN
THE LOWER LEVELS INCREASES THERE WILL BE A CHANCE FOR A FEW SHOWERS.
THESE SHOWERS WILL BE FORMING ON A LOW LEVEL CONVERGENT BOUNDARY AS
LOW LEVEL WINDS INCREASE TOWARDS 30 KNOTS. THESE SHOWERS WILL BE
LIFTING FROM SOUTHWEST TO NORTHEAST THROUGH THE NIGHT. WITH THE
WARMING AIRMASS AND THE SOUTHERLY WINDS THROUGH THE NIGHT LOWS WILL
REMAIN ON THE MILD SIDE...WITH MANY AREAS IN THE UPPER 50S TO LOWER
60S.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
FOR THIS PERIOD ABOVE AVERAGE TEMPERATURES WILL BE THE RULE DURING
THE FIRST HALF OF THIS PERIOD BEFORE A COOLING TREND TAKES PLACE
LATE IN THE WEEK AS A DEEPENING UPPER LEVEL TROUGH SETS UP OVER
SOUTHERN QUEBEC AND THE NORTHEAST PART OF THE U.S..
AT THE SURFACE...THE SOUTHWEST FLOW BETWEEN HIGH PRESSURE ANCHORED
OFF THE EAST COAST AND LOW PRESSURE TRACKING JUST NORTH OF THE GREAT
LAKES WILL BRING VERY WARM AIR INTO OUR AREA. WITH 850 MB
TEMPERATURES FORECAST TO RISE INTO THE UPPER TEENS...SURFACE
TEMPERATURES WILL WARM INTO THE 80S. A FEW SPOT 90S CANNOT BE RULED
OUT ACROSS THE GENESEE VALLEY ON TUESDAY. SLIGHTLY LOWER HEIGHTS
WEDNESDAY AND POSSIBLE MORE CLOUDS MAY LEAD TO TEMPERATURES A HAIR
COOLER ON WEDNESDAY THAN TUESDAY. THE WARM TEMPERATURES WILL ALSO BE
ACCOMPANIED BY AN INCREASE IN HUMIDITY AS A RETURN FLOW OFF ATLANTIC
PUSHES DEWPOINTS BACK INTO THE 60S...MAKING IT FEEL MORE LIKE LATE
JULY THAN MID-SEPTEMBER.
IN TERMS OF PCPN...A LIFTING WARM FRONT WILL BRING A FEW SHOWERS AND
POSSIBLY AN ISOLATED THUNDERSTORM TO OUR NORTHERN PORTIONS OF THE
CWA ON TUESDAY. THESE STORMS WILL FUEL OFF PWATS CLIMBING BACK
TOWARDS 1.5 INCHES AND GREATER. WILL BRING CHANCE POPS ACROSS THE
CWA AS THE BEST ISENTROPIC LIFT WILL REMAIN JUST TO OUR WEST. EXPECT
A DRYING TREND THEN THROUGH THE AFTERNOON TUESDAY WITH SOME BREAKS
OF SUNSHINE. MORE UNSTABLE AIR AHEAD OF AN APPROACHING COLD FRONT
BRINGS A CHANCE FOR SHOWERS AND THUNDERSTORMS TUESDAY NIGHT AND
WEDNESDAY. THE WINDS LATER ON WEDNESDAY WITHIN THE LOWER 5K INCREASE
TO 35 TO 40 KNOTS...WHICH WHEN COMBINED WITH SBCAPES EXCEEDING 1000
J/KG MAY BRING A FEW STRONGER THUNDERSTORMS ON WEDNESDAY AND
WEDNESDAY NIGHT.
THERE IS STILL A LITTLE UNCERTAINTY BETWEEN THE MODELS WITH THE
CROSSING OF THE COLD FRONT. LATEST GUIDANCE SUGGESTS THAT THE FRONT
WILL CROSS OUR AREA WEDNESDAY NIGHT OR THURSDAY...WITH A CLEARING OF
THE HUMIDITY AND WARM AIRMASS WITH A SECONDARY COLD FRONT THAT WILL
DROP ACROSS THE REGION THURSDAY NIGHT. WILL MAINTAIN CHANCE POPS FOR
SHOWERS AND THUNDERSTORMS WITH THE FRONTAL PASSAGE THROUGH THURSDAY
NIGHT. WHILE IT WILL BE COOLER ON THURSDAY...TEMPERATURES WILL BE CLOSE
AVERAGE.
THE DEEPENING UPPER LEVEL TROUGH AND NORTHWEST FLOW BEHIND THE
DEPARTING COLD FRONT WILL ALLOW COOLER AIR TO DEEPEN ACROSS THE
REGION FRIDAY. HIGHS FALL BACK INTO THE BELOW NORMAL RANGE WITH
AFTERNOON TEMPERATURES STRUGGLING INTO THE LOWER 60S WITH A BRISK
BREEZE.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AN AREA OF SHOWERS ACROSS MUCH OF UPSTATE NY EARLY THIS AFTERNOON
WILL CONTINUE THROUGH THE FIRST HALF OF TONIGHT AS A COLD FRONT
PUSHES SOUTH ACROSS THE AREA. CONDITIONS WILL STAY VFR MUCH OF THE
TIME THROUGH THIS EVENING AS THE LOW LEVELS REMAIN UNSATURATED...
ALTHOUGH SOME BRIEF DIPS TO MVFR/IFR VSBY ARE POSSIBLE IN THE
HEAVIEST SHOWERS.
FOLLOWING THE COLD FRONTAL PASSAGE IN THE 05Z-07Z TIME FRAME...
SHOWERS WILL TAPER OFF FROM NORTH TO SOUTH. A FEW LINGERING LIGHT
SHOWERS MAY PERSIST THROUGH SUNDAY MORNING ACROSS HIGHER TERRAIN DUE
TO UPSLOPE FLOW...AND SOUTHEAST OF LAKE ONTARIO DUE TO SOME WEAK
LAKE EFFECT AS COOLER AIR CROSSES THE LAKE. OF MORE IMPORTANCE...A
PERIOD OF LOWER CIGS IS EXPECTED FOLLOWING THE COLD FRONTAL PASSAGE
AS EXTENSIVE LOW LEVEL MOISTURE BECOMES TRAPPED UNDER A STEEP
FRONTAL INVERSION. THIS WILL BRING AREAS OF IFR CIGS LATER TONIGHT
THROUGH SUNDAY MORNING. THE LOW CIGS WILL SCATTER OUT FROM NORTH TO
SOUTH ON SUNDAY AS DRIER AIR AND SUBSIDENCE BUILD SOUTH OUT OF
ONTARIO WITH HIGH PRESSURE BUILDING BACK INTO THE GREAT LAKES.
OUTLOOK...
MONDAY AND TUESDAY...MAINLY VFR.
WEDNESDAY...MVFR/VFR. A CHANCE OF THUNDERSTORMS.
THURSDAY...MVFR/VFR WITH A CHANCE OF SHOWERS.
&&
.MARINE...
THE SW FLOW WILL INCREASE TODAY AHEAD OF THE FRONT...AND THIS SHOULD
BE JUST ENOUGH TO BRING SMALL CRAFT CONDITIONS TO EASTERN LAKE
ERIE...AND THE UPPER NIAGARA RIVER. THEN MORE WIDESPREAD SMALL CRAFT
CONDITIONS WILL DEVELOP ON SUNDAY IN THE NORTHERLY FLOW BEHIND THE
FRONT. WAVES WILL BUILD TO AROUND 5 FEET ALONG THE SOUTH SHORES OF
LAKE ONTARIO. SMALL CRAFT ADVISORY CONDITIONS ARE ALSO LIKELY AGAIN
ON LAKE ERIE MAINLY FROM DUNKIRK TO THE PA STATE LINE AS NORTH TO
NORTHEAST WINDS INCREASE BEHIND THE COLD FRONT.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ041.
SMALL CRAFT ADVISORY UNTIL 4 PM EDT SUNDAY FOR LEZ040.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
LEZ020.
SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM EDT SUNDAY FOR
LOZ030.
SMALL CRAFT ADVISORY FROM 6 AM TO 11 PM EDT SUNDAY FOR
LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT SUNDAY FOR
LOZ042-045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL/HITCHCOCK
SHORT TERM...THOMAS
LONG TERM...THOMAS/TJP
AVIATION...HITCHCOCK
MARINE...APFFEL/HITCHCOCK
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1256 PM CDT SAT SEP 7 2013
.UPDATE...
ISSUED AT 1240 PM CDT SAT SEP 7 2013
BATCH OF SCATTERED SHOWERS WITH A FEW EMBEDDED LIGHTNING STRIKES
TRACKING ALONG THE BOUNDARY NEAR OUR SOUTHERN BORDER. THIS ACTIVITY
CONTINUES TO TRACK EAST SOUTHEAST AND SHOULD EXIT THE AREA WITHIN THE
NEXT FEW HOURS. WHILE CLEARING IS FORMING BEHIND THIS
ACTIVITY...CLOUD COVERAGE IS STALLING THE WARMING ACROSS OUR
SOUTHEASTERN HALF. DID LOWER HIGHS A FEW DEGREES MAINLY THROUGH
NORTHWEST IOWA AND ADJACENT AREAS WHERE THE CLOUDS WILL HOLD ON
LONGEST THIS AFTERNOON. THE ARRIVAL OF SUNSHINE ELSEWHERE SHOULD
ALLOW TEMPS TO SHOOT UP FAIRLY QUICKLY.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM CDT SAT SEP 7 2013
TOUGH FORECAST FOR TODAY WITH A SERIES OF WEAK WAVES PASSING THROUGH
THE AREA AS THEY RIDE ALONG THE NORTHERN EDGE OF THE UPPER LEVEL
RIDGE ACROSS THE CENTRAL PLAINS. HRRR SEEMS TO HAVE A REASONABLE
HANDLE ON CONVECTION ACROSS CENTRAL SOUTH DAKOTA. HAVE FOLLOWED THE
HI RES ARW CORE IN TERMS OF FORCING WHICH SUGGESTS WEAK SHORT WAVE
MOVING THROUGH THE SOUTHERN HALF OF THE FORECAST AREA THROUGH THE
MORNING. IN GENERAL...ACTIVITY SHOULD FOLLOW THERMAL WIND WHICH
WOULD BRING IT ACROSS THE CENTRAL AND SOUTHERN HALF OF THE FORECAST
AREA. ATMOSPHERE APPEARS TO BE MODERATELY UNSTABLE WITH 500-1000
J/KG IN ELEVATED CAPE LARGELY IN PART TO STEEP LAPSE RATES FROM
700-500MB. SHEAR IS VERY WEAK...SO DO NOT EXPECT THIS ACTIVITY TO
BECOME ALL THAT ORGANIZED OR SEVERE.
BEHIND THIS WAVE THERE APPEARS TO BE A BREAK IN THE ACTIVITY WITH
ANOTHER WARM AND HUMID DAY SETTING UP. WITH NORTHEAST FLOW SETTING
UP BEHIND THIS SYSTEM...AM CONCERNED IT WILL BE HARD TO MIX
EFFICIENTLY...AND SIDED WITH COOL FORECAST HIGHS CLOSE TO THE
BCCONSALL. ALSO THINK THE CLOUDS WILL BE SOMEWHAT STUBBORN TO LEAVE
ACROSS NORTHWEST IOWA...AND HAVE COOLED TEMPERATURES THERE SLIGHTLY.
QUESTIONS ABOUND TONIGHT AS NORTHEAST FLOW BECOMES EASTERLY. MODEL
SOUNDINGS HINT TOWARDS LOW LEVEL SATURATION ACROSS THE EASTERN
CWA...GRADUALLY EXPANDING BACK TO THE WEST THROUGHOUT THE NIGHT.
HAVE RAISED SKY COVER IN THE EAST.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 406 AM CDT SAT SEP 7 2013
EASTERLY FLOW ENTRENCHED OVER THE AREA ON SUNDAY. SIGNS THAT WE COULD
BE DEALING WITH SOME MORNING LOW STRATUS ACROSS SOUTHWEST MINNESOTA.
THE MOIST LOW LEVELS WILL ALSO LIKELY LEAD TO STRATOCU DEVELOPMENT
ONCE DAYTIME HEATING KICKS IN...ESPECIALLY ALONG AND EAST OF
INTERSTATE 29. THUS PROBABLY LOOKING AT ONLY A PARTLY SUNNY DAY
ACROSS THE EAST...WITH MAYBE A BIT MORE SUN AS YOU GO SOUTHWEST.
SHOULD BE A MAINLY DRY DAY...ALTHOUGH BOTH THE HI RES NAM AND ARW
SUGGEST THAT OVERNIGHT STORMS ACROSS THE WESTERN PLAINS MAY MAKE IT
INTO OUR FAR WEST TOWARDS 12Z IN A WEAKENING STATE. THUS WILL CARRY
A SMALL POP OUT THERE FOR THE MORNING HOURS. DESPITE WARM
TEMPERATURES ALOFT...THE PATTERN WILL REMAIN NOT FAVORABLE FOR GOOD
MIXING. AND THUS WILL KEEP HIGHS CLOSER TO THE COOLER BIAS CORRECTED
GUIDANCE...GIVING MID 80S EAST TO LOW 90S IN SOUTH CENTRAL SOUTH
DAKOTA. IT WILL REMAIN HUMID WITH DEWPOINTS IN THE 60S TO AROUND 70.
LOOKING LIKE A VERY MILD NIGHT AS THE LOW LEVEL JET INCREASES
KEEPING A 10 TO 20 MPH WIND AT THE SURFACE AND HOLDING LOWS IN THE
UPPER 60S TO LOWER 70S. SHOULD SEE QUITE A BIT OF SHOWER AND
THUNDERSTORM DEVELOPMENT SUNDAY NIGHT AS WELL WITH INCREASING
ISENTROPIC LIFT AND CONVERGENCE ON THE NOSE OF THE STRENGTHENING LOW
LEVEL JET...HOWEVER MUCH OF THIS ACTIVITY IS EXPECTED TO STAY NORTH
OF OUR CWA. ALTHOUGH ABOUT 40 TO 60 PERCENT OF THE SREF MEMBERS AND
THE GFS SUGGEST THAT THE ACTIVITY COULD CLIP THE HIGHWAY 14
CORRIDOR...MAINLY IN SOUTHWEST MINNESOTA. SO WILL GO WITH A 20 TO 30
POP IN THAT REGION.
MONDAY IS SHAPING UP TO BE A HOT ONE ACROSS THE AREA. IT WOULD
APPEAR LIKE MIXING WOULD BE PRETTY GOOD...WITH COMPRESSIONAL HEATING
AHEAD OF AN APPROACHING COLD FRONT AND A BLUSTERY SOUTHWESTERLY
WIND. GIVEN OUR RECENT STRUGGLE TO REACH THE WARMER GUIDANCE EAST OF
THE JAMES RIVER...AND UNCERTAINTY ON TIMING OF THE FRONT...WAS
HESITANT TO GO TOO HOT WITH HIGHS. HOWEVER EVEN MIXING IN SOME OF
THE COOLER BIAS CORRECTED DATA STILL RESULTS IN LOW TO MID 90S EAST
OF THE JAMES RIVER. IF WE END UP FULLY MIXING THINGS OUT...HIGHS
COULD EVEN BE A FEW DEGREES WARMER THAN THE CURRENT FORECAST.
CONVECTION CHANCES WITH THE FRONTAL BOUNDARY A BIT TRICKY. HOWEVER
MOST INDICATIONS ARE THAT ANYTHING WOULD LIKELY BE POST
FRONTAL...WITH THE PRE FRONTAL AIRMASS REMAINING CAPPED. EXPECTING
DECENT FRONTOGENETICAL FORCING...AND OUR AREA WILL BE IN THE RIGHT
ENTRANCE REGION OF A 60 TO 80 KT UPPER LEVEL JET. SO EVEN THOUGH THE
BEST PV FORCING WILL STAY TO OUR NORTH...STILL LOOKS LIKE DECENT
DYNAMICS OVERHEAD. SHOULD BE PLENTY OF MOISTURE PRESENT AS
WELL...WITH PWATS EXPECTED TO BE 2 TO 3 STANDARD DEVIATIONS ABOVE
NORMAL. SO LOOKS LIKE A PRETTY GOOD CHANCE WE SEE SHOWER AND
THUNDERSTORM DEVELOPMENT FROM LATE AFTERNOON INTO THE OVERNIGHT.
INDICATIONS THAT THE SWATH OF ACTIVITY WILL NOT BE TOO WIDE...AND
THUS WITH UNCERTAINTY IN FRONTAL TIMING AND LOCATION OF BEST
FORCING...WILL JUST KEEP HIGH CHANCE POPS FOR NOW. SEVERE THREAT
LOOKS ON THE LOW SIDE. INSTABILITY SHOULD DROP OFF POST FRONTAL
ENOUGH TO LIMIT THE POTENTIAL. ALTHOUGH WITH SHEAR
INCREASING...COULD STILL END UP WITH A FEW ISOLATED STRONGER STORMS.
MAIN THREAT MAY BE SOME LOCALLY HEAVY RAIN...GIVEN THE HIGH
PWATS...SLOW MOVING FRONT...AND A GOOD COMPONENT OF THE STORM MOTION
PARALLEL TO THE FRONT.
BY TUESDAY THE BEST CHANCE OF SHOWERS AND STORMS WILL BE ACROSS
NORTHWEST IOWA AND POINTS SOUTH AS THE FRONT CLEARS THE CWA. COOLER
AND LESS HUMID AIR WILL FILTER INTO THE REGION TUESDAY INTO
WEDNESDAY AS THE FRONT AND WAVE HELP FLATTEN THE RIDGE. ALTHOUGH
HIGHS WILL REMAIN ABOVE AVERAGE...WITH LOW TO MID 80S EXPECTED. AS
MENTIONED...DEWPOINTS WILL FALL INTO THE 50S BY WEDNESDAY THOUGH. A
WAVE PUSHING INTO THE GREAT LAKES REGION WILL HELP SUPPRESS THE
RIDGE EVEN MORE THURSDAY INTO FRIDAY...HELPING US COOL OFF A BIT
MORE. MODELS NOW IN PRETTY GOOD AGREEMENT ON THE EXTENT OF THE
COOLING ALOFT...SUGGESTING WE SEE HIGHS RANGING FROM THE MID 70S IN
SOUTHWEST MINNESOTA TO NEAR 80 ALONG THE MISSOURI RIVER. BOTH DAYS
SHOULD BE DRY...ALTHOUGH AS THE RIDGE BEGINS TO BUILD BACK IN WE MAY
HAVE TO DEAL WITH AN INCREASING THUNDERSTORM THREAT BY FRIDAY NIGHT.
LONG RANGE ENSEMBLES SUGGEST THAT AFTER THIS BRIEF PUSH TO NEAR
NORMAL TEMPERATURES WE WILL TEND TO SEE ANOTHER ABOVE NORMAL STRETCH
OF TEMPERATURES THE FOLLOWING WEEK.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1240 PM CDT SAT SEP 7 2013
VFR CONDITION PREDOMINATE THROUGH THE TAF PERIOD. SCATTERED STORMS
FROM NEAR YANKTON EASTWARD INTO NORTHWEST IOWA WILL CONTINUE TO
DISSIPATE AS THEY TRACK EAST SOUTHEAST. COULD SEE A BRIEF DIP TO
LOWER CONDITIONS IN THUNDERSTORMS BUT ACTIVITY WILL COME TO AN END BY
20Z. MODELS HINTING AT THE POSSIBILITY OF SOME BROKEN STRATUS FORMING
TONIGHT...MAINLY ACROSS SOUTHWEST MINNESOTA. WILL LEAVE OUT MENTION
AT TAF SITES FOR NOW BUT WILL CONTINUE TO WATCH FOR DEVELOPMENT.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
UPDATE...
SHORT TERM...
LONG TERM...CHENARD
AVIATION...
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1103 AM CDT SAT SEP 7 2013
.UPDATE...
MOIST AXIS WITH PRECIPITABLE WATER VALUES OF 1.8 ON RAP ANALYSIS AND
ON THE NOSE OF THE 850MB MOISTURE TRANSPORT AND THETA-E ADVECTION
ARE CENTERED RIGHT OVER CENTRAL AND SOUTH CENTRAL WISCONSIN THIS
MORNING. A CLUSTER OF THUNDERSTORMS IS MOVING ACROSS FOND DU LAC AND
SHEBOYGAN COUNTIES LATE THIS MORNING. THERE IS POTENTIAL FOR THE
STRONGER CORES TO PRODUCE SMALL HAIL WITH THIS ELEVATED
CONVECTION...WITH ELEVATED CAPE OF 700-1000 J/KG.
MESOSCALE MODELS ARE SUGGESTING CONVECTION TO DEVELOP THIS AFTERNOON
OVER SOUTHERN WI AHEAD OF THE SURFACE FRONT. THE FORECAST ISSUE
IS WHETHER OR NOT THE SURFACE AND UPPER LEVEL SUPPORT WILL COME IN
LINE TOGETHER TO PRODUCE ORGANIZED CONVECTION. IT IS NOT LOOKING
LIKE ALL FACTORS WILL BE LINED UP AT THE SAME TIME. IN ADDITION TO
AN ACCELERATING SURFACE FRONT...THERE WILL BE UPPER LEVEL SUPPORT
FROM A WEAK SHORTWAVE...PERSISTENT LOW LEVEL JET/MOISTURE TRANSPORT
AND SUBTLE RIGHT ENTRANCE REGION OF AN UPPER JET.
TIMING IS AN ISSUE AS WELL...WITH THE NAM SHOWING BETTER POTENTIAL
FOR EARLY CONVECTION AND THE HRRR BEGINNING MID AFTERNOON...AND THE
WRF-ARW MODELS SHOWING LATE AFTERNOON/EVENING. COVERAGE WILL BE
SPOTTY...BUT WILL PROBABLY NEED TO RAISE THE POPS A BIT. SPC
CONTINUES TO HAVE A SEE TEXT AREA FOR A FEW THUNDERSTORMS TO
POTENTIALLY BECOME SEVERE WITH WINDS/HAIL DURING THE AFTERNOON.
GUSTY NORTHEAST WINDS IN THE WAKE OF THE COLD FRONT WILL WORK DOWN
THE LAKE THIS EVENING. DELAYED COLD AIR ADVECTION WILL LEAD TO LOW
CLOUDS SPREADING INLAND...PROBABLY THROUGH MADISON...EARLY SUNDAY
MORNING. THESE WOULD GRADUALLY RISE AND MIX OUT SUNDAY AFTERNOON.
&&
.AVIATION/18Z TAFS/...
ISOLATED SHOWERS WITH A FEW ELEVATED THUNDERSTORMS WILL BE POSSIBLE
THROUGH THE MORNING. A CLUSTER OF STRONGER THUNDERSTORMS LOCATED
NEAR FOND DU LAC AND OSHKOSH AT 1030 WILL MOVE SOUTHEAST THROUGH
SHEBOYGAN THROUGH NOON TODAY.
SCATTERED THUNDERSTORMS ARE EXPECTED IN THE VICINITY OF A COLD FRONT
SLOWLY DROPPING DOWN THROUGH SOUTHERN WI THIS AFTERNOON AND EVENING.
ANY STRONGER STORMS COULD PRODUCE SMALL HAIL AND GUSTY WINDS.
SOME MVFR CLOUDS POSSIBLE BEHIND THE FRONT LATER TONIGHT INTO SUNDAY
MORNING IN THE WAKE OF THE COLD FRONT. THESE WILL GRADUALLY RISE TO
VFR AND SCATTER OUT SUNDAY AFTERNOON. GUSTY NORTHEAST TO EAST WINDS
EXPECTED LATE TONIGHT/SUNDAY MORNING...ESPECIALLY NEAR THE
LAKESHORE.
&&
.MARINE...
SOUTHWEST WINDS AHEAD OF A COLD FRONT THROUGH EARLY AFTERNOON. A
COLD FRONT WILL THEN DROP SOUTH LATE THIS AFTERNOON AND EVENING.
NORTHEAST WINDS WILL RAPIDLY INCREASE FROM MID TO LATE EVENING NORTH
TO SOUTH BEHIND THE FRONT. WIND GUSTS AND SUBSEQUENT WAVES ARE
EXPECTED TO REACH SMALL CRAFT ADVISORY CRITERIA LATE TONIGHT THROUGH
SUNDAY AFTERNOON...WITH GRADUAL IMPROVEMENT SUNDAY EVENING.
&&
.PREV DISCUSSION... /ISSUED 312 AM CDT SAT SEP 7 2013/
SHORT TERM...
TODAY AND TONIGHT-FORECAST CONFIDENCE MEDIUM TO HIGH.
THE UPPER LEVEL WEST/NORTHWEST FLOW ACROSS THE GREAT LAKES WILL
BECOME MORE NORTHWEST AS A JET MAX INCREASES TO AROUND 95 KNOTS OVER
THE EASTERN LAKE SUPERIOR AREA THIS AFTERNOON...BEFORE DROPPING INTO
LOWER MICHIGAN TONIGHT. AT 500 MB A WEAK SHORTWAVE WILL DROP
SOUTHEAST ACROSS SOUTHERN WISCONSIN THIS MORNING AND EXIT INTO
NORTHERN INDIANA THIS AFTERNOON. THE 850/700 MB FLOW IS WEAK AS IS
THE MOISTURE CONVERGENCE/UPWARD MOTION.
THE SURFACE COLD FRONT SHOULD ENTER SOUTHERN WISCONSIN DURING THE
EARLY AFTERNOON BEFORE EXITING THE FAR SOUTH TOWARD EVENING.
ZERO TO 1 KM CAPE VALUES INCREASE TO AROUND 2500 J/KG BUT THIS IS
MAINLY POST FRONTAL OVER PORTIONS OF SOUTH CENTRAL WISCONSIN.
ALL IN ALL THERE ARE SEVERAL MECHANISMS FOR SHOWER/THUNDERSTORM
POTENTIAL...BUT THEY DO NOT ALL COME TOGETHER AT ONE TIME.
THEREFORE A BROAD WINDOW OF LOW POPS APPEAR TO BE THE BEST COURSE OF
ACTION. SPC CONTINUES TO HAVE A SEE TEXT AREA FOR A FEW
THUNDERSTORMS TO POTENTIALLY BECOME SEVERE WITH WINDS/HAIL. THIS
WOULD OCCUR DURING THE AFTERNOON.
SUNDAY-FORECAST CONFIDENCE HIGH
SURFACE HIGH MOVES OUT OF ONTARIO INTO MICHIGAN WITH COOL AND DRY
EASTERLY FLOW. UPPER RIDGE REMAINS ANCHORED OVER KANSAS WITH
NORTHWEST FLOW PERSISTING OVER SOUTHERN WISCONSIN.
MONDAY-FORECAST CONFIDENCE HIGH
UPPER TROUGH CURRENTLY OVER PACIFIC NORTHWEST MOVES ACROSS DAKOTAS
DURING THE DAY AND INTO MINNESOTA AT NIGHT. THIS FLATTENS UPPER
RIDGE WHICH SHIFTS TO THE EAST AND FLOW TURNS TO WESTERLY AND
EVENTUALLY SOUTHWEST OVER WISCONSIN. SURFACE LOW OF AROUND 1000 MB
MOVES OUT OF DAKOTAS INTO MINNESOTA BY THE EVENING AND THEN CROSSES
LAKE SUPERIOR OVERNIGHT.
MODELS SHOW NOSE OF LOW LEVEL JET AND SIGNIFICANT WARM ADVECTION
REGIME STAYING WELL NORTH OF THE AREA WITH THUNDERSTORMS NOW EVEN
FURTHER NORTH THAN MODELS DEPICTED 24 HOURS AGO. LOOKS LIKE BULK OF
ACTIVITY WILL BE IN LAKE SUPERIOR AREA AND NORTHWEST ONTARIO. 500 MB
HEIGHTS ACTUALLY RISE 10-20 METERS OVER SOUTHERN WISCONSIN.
LONG TERM...
TUESDAY-FORECAST CONFIDENCE HIGH
SURFACE LOW MOVES ACROSS ONTARIO AND INTO QUEBEC WITH FRONT SLOWING
DOWN AS IT SAGS SOUTH THROUGH SOUTHERN WISCONSIN IN THE AFTERNOON.
GFS IS ONE OF THE SLOWER SOLUTIONS AND HAS 925 MB TEMPS AROUND
+28C...SUGGESTING MID TO UPPER 90S. BOTH NAM AND GFS HAVE PLUME OF
WARM AND DRY AIR JUST AHEAD OF FRONT SPREADING OUT OF THE CENTRAL
PLAINS WHERE IT HAS BEEN RATHER HOT OF LATE AND THERE IS THE
POTENTIAL THAT CURRENT FORECAST IN THE LOWER 90S IS CONSERVATIVE.
LAST TWO RUNS OF ECMWF HAVE FRONT MAKING IT THROUGH FASTER...WHICH
SUGGESTS MORE CONSERVATIVE TEMPERATURE FORECAST IS IN ORDER.
GFS ECMWF AND GEMNH ARE IN RATHER GOOD AGREEMENT IN NARROW PLUME OF
MOISTURE JUST BEHIND THE SURFACE FRONT WITH MOISTURE ADVECTING OUT
OF SOUTHWESTERN STATES. LOOKS LIKE MOST OF THIS CONVECTIVE ACTIVITY
WOULD BE AT NIGHT WHEN MODEST HEIGHT FALLS OF ABOUT 20 METERS
OCCUR.
WEDNESDAY-FORECAST CONFIDENCE HIGH
FRONT PUSHES WELL SOUTH BUT A SECOND REINFORCING COOL SURGE IS SHOWN
TO COME DOWN AS A BROAD UPPER TROUGH DEVELOPS OVER CENTRAL AND
EASTERN CANADA. STRONGEST HEIGHT FALLS OF ABOUT 100 METERS MOVE
ACROSS NORTHERN MICHIGAN WITH STRONGER DYNAMICS JUST BRUSHING
SOUTHERN WISCONSIN. SHOULD BE DRY WITH TEMPERATURES RETURNING MORE
TOWARD SEASONABLE LEVELS.
THURSDAY-FORECAST CONFIDENCE HIGH
MODELS HAVE COME INTO BETTER AGREEMENT IN DIGGING ANOTHER TROUGH IN
NORTHWEST FLOW INTO THE GREAT LAKES. THIS FEATURE IS NOT AS
AMPLIFIED AS ECMWF DEPICTED A FEW RUNS AGO...BUT WOULD CONTINUE TO
PUSH COOLER AIR INTO GREAT LAKES. IN FACT GFS DROPS 850 MB TEMPS
DOWN INTO ABOUT +6C WHICH WOULD BE LOW ENOUGH FOR LAKE EFFECT
SHOWERS. HOWEVER THE FETCH WOULD LIKELY KEEP THEM OFFSHORE.
FRIDAY-FORECAST CONFIDENCE HIGH
DRY AND COOL NORTHWEST FLOW ALOFT SHOULD CONTINUE WITH LARGE SURFACE
HIGH OVER MICHIGAN AND LIGHT SURFACE FLOW.
AVIATION/12Z TAFS/...
MAINLY VFR CONDITIONS. A MID LEVEL CLOUD DECK WILL DROP INTO
SOUTHERN WISCONSIN EARLY THIS MORNING WITH ISOLATED SHOWERS WITH
A FEW ELEVATED THUNDERSTORMS. THEN SCATTERED THUNDERSTORMS
ARE EXPECTED IN THE VICINITY OF A COLD FRONT SLOWLY DROPPING DOWN
THROUGH SOUTHERN WI THIS AFTERNOON AND EVENING.
SOME MVFR CLOUDS POSSIBLE BEHIND THE FRONT LATER TONIGHT INTO SUNDAY
MORNING.
MARINE...
SOUTHWEST WINDS AHEAD OF A COLD FRONT THIS MORNING. A COLD FRONT
WILL THEN DROP SOUTH THIS AFTERNOON. NORTHEAST WINDS WILL INCREASE
TONIGHT BEHIND THE FRONT. WINDS/WAVES MAY REACH SMALL CRAFT
ADVISORY CRITERIA LATE TONIGHT AND INTO SUNDAY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 1 AM TO 7 PM CDT SUNDAY FOR LMZ645-646.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM CDT SUNDAY
FOR LMZ643-644.
&&
$$
UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
SUNDAY THROUGH FRIDAY...CRAVEN