Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/22/12
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
916 AM PDT THU SEP 20 2012
.SHORT TERM DISCUSSION...
A LOOK OVER CURRENT FORECAST AND MODELS SEEMS THAT FORECAST IS IN
REALLY GOOD SHAPE. THE BIGGEST CHALLENGE FOR THIS PACKAGE WILL BE
THE UPPER LOW PROGGED TO SLIDE SOUTH INTO AREA SATURDAY NIGHT AND
SUNDAY. AT THIS TIME...PRETTY GOOD AGREEMENT THAT THE MAIN IMPACTS
OF THIS UPPER LOW SHOULD REMAIN OUT OF OUR AREA...BUT TREND THIS
SUMMER FOR SYSTEMS LIKE THIS HAVE BEEN TO SLIDE A BIT FURTHER WEST
THAN MODELS EXPECT. IF THIS WHERE TO HAPPEN SHOWER AND
THUNDERSTORMS CHANCE WOULD HAVE BE INCREASED IN AREAL COVERAGE A
BIT TO THE WEST. CURRENT FORECAST DOES ALLOW FOR SOME ERROR IN A
WESTERN LOCATION. WILL SEE HOW NEW ECMWF AND GFS LINE UP WITH
MORNING NAM FOR AFTERNOON PACKAGE...BUT RIGHT NOW...NO UPDATES
NEEDED FOR MORNING UPDATE. RASCH
.EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)
BY MONDAY AFTERNOON...ALL MODELS NOW MOVE UPPER LOW CENTER INTO
THE GREAT BASIN. HAVE REDUCED THREAT OF THUNDERSTORMS OVER SIERRA
FOR MONDAY BUT RAP AROUND ACTIVITY COULD SPARK SOME ISOLATED
THUNDERSTORMS OVER THE CREST. MODELS DIVERGE SOMEWHAT BY NEXT
TUESDAY IN DEALING WITH ANOTHER WEAK PACIFIC TROUGH FORECAST TO
MOVE ONTO THE NORCAL COAST. AT THIS TIME...IT APPEARS THIS SYSTEM
WILL BE TOO WEAK TO PRODUCE A SIGNIFICANT THREAT OF SHOWERS OR
THUNDERSTORMS. GFS MOVES THIS LOW QUICKLY THROUGH NORCAL ON
WEDNESDAY WHILE GEM AND ECMWF DROP THE TROUGH SOUTHWARD FORMING A
CLOSED LOW SOMEWHERE ALONG THE CENTRAL CALIFORNIA COAST. GEM/ECMWF
SOLUTION WOULD BRING A THREAT OF SHOWERS OR THUNDERSTORMS TO THE
SIERRA CASCADE CREST WHILE GFS WOULD KEEP FORECAST AREA DRY ON
WEDNESDAY. WILL KEEP SLIGHT THREAT OF THUNDERSTORMS IN FOR THE
SIERRA CASCADE RANGE ON WEDNESDAY AND THURSDAY FORECAST PERIOD
UNTIL MODELS COME INTO BETTER ALIGNMENT. OTHERWISE MAINLY FAIR
SKIES CONTINUE WITH NEAR NORMAL TEMPERATURES.
&&
.AVIATION...VFR CONDITIONS EXPECTED NEXT 24 HOURS EXCEPT
POSSIBLE MVFR CONDITIONS WITH PATCHY LOW CLOUDS IN THE DELTA
REGION WEST OF KSUU THROUGH 16Z. SOUTHWEST WINDS UP TO 20 KTS IN
THE DELTA...WITH TAF SITES GENERALLY LESS THAN 12 KTS. -DVC
&&
.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
415 AM PDT THU SEP 20 2012
.DISCUSSION...A LOW PRESSURE SYSTEM CONTINUES TO SPIN OFFSHORE
WHILE AN UPPER LEVEL HIGH PRESSURE SYSTEM REMAINS OVER THE WEST
COAST. THIS HIGH PRESSURE RIDGE IS CURRENTLY BRINGING CLEAR SKIES TO
THE FORECAST AREA THIS MORNING. THE LOW AND RIDGE ARE ONLY EXPECTED
TO MOVE SLIGHTLY TODAY SO NOT EXPECTING MUCH CHANGE IN AIRMASS.
TEMPERATURES THIS MORNING ARE RUNNING SIMILAR TO 24 HOURS AGO AND
EXPECTING TODAYS HIGHS TO COME IN SIMILAR TO WEDNESDAYS. THE
OFFSHORE UPPER LOW IS FORECAST BY ALL MODELS TO OPEN AND LIFT TO THE
NORTHEAST TOWARDS THE PACIFIC NORTHWEST ON FRIDAY. AIRMASS COOLS
JUST A BIT SO HIGHER ELEVATIONS MAY SEE A LITTLE COOLING FRIDAY. NAM
MODEL SHOWS JUST A BIT OF INSTABILITY IN THE MID LEVELS OVER THE
NORTHERN SIERRA ZONES. MOISTURE WILL BE LIMITED BUT WILL LIKELY BE
ENOUGH FOR SOME AFTERNOON CUMULUS. ALSO ADDED JUST A SLIGHT THREAT
OF AFTERNOON THUNDERSTORMS OVER THE FAR SOUTHEASTERN CWA. AIRMASS
COOLS A BIT MORE ON SATURDAY AS THE UPPER TROUGH BEGINS PUSHING INTO
THE PACIFIC NORTHWEST COAST. MODELS INDICATE RELATIVELY STABLE
SOUTHWEST FLOW ALOFT BUT MAY BE JUST ENOUGH LIFT AND INSTABILITY
OVER PORTIONS OF THE SIERRA CASCADE CREST TO PRODUCE SOME ISOLATED
THUNDERSTORM ACTIVITY. MODELS ARE IN BETTER AGREEMENT IN POSITION OF
THE TROUGH ON SATURDAY THAN IN PREVIOUS RUNS SO WITH MORE
CONFIDENCE...HAVE LOWERED POPS A BIT OVER THE SIERRA CASCADE CREST
REGION. MID RANGE MODELS NOW IN FAIRLY GOOD AGREEMENT IN DIGGING
UPPER TROUGH SOUTHWARD ON SUNDAY FORMING ANOTHER CLOSED LOW CENTERED
OVER NORTHEAST CALIFORNIA. MODELS STILL NOT SHAPING NORCAL UP TO BE
PARTICULARLY UNSTABLE BUT WITH PROXIMITY OF LOW OVER NORCAL...SLIGHT
THREAT OF AFTERNOON THUNDERSTORMS SEEMS FAIRLY REASONABLE AND
MATCHES WELL WITH SURROUNDING OFFICE FORECASTS.
&&
.EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)
BY MONDAY AFTERNOON...ALL MODELS NOW MOVE UPPER LOW CENTER INTO THE
GREAT BASIN. HAVE REDUCED THREAT OF THUNDERSTORMS OVER SIERRA FOR
MONDAY BUT RAP AROUND ACTIVITY COULD SPARK SOME ISOLATED
THUNDERSTORMS OVER THE CREST. MODELS DIVERGE SOMEWHAT BY NEXT
TUESDAY IN DEALING WITH ANOTHER WEAK PACIFIC TROUGH FORECAST TO MOVE
ONTO THE NORCAL COAST. AT THIS TIME...IT APPEARS THIS SYSTEM WILL BE
TOO WEAK TO PRODUCE A SIGNIFICANT THREAT OF SHOWERS OR
THUNDERSTORMS. GFS MOVES THIS LOW QUICKLY THROUGH NORCAL ON
WEDNESDAY WHILE GEM AND ECMWF DROP THE TROUGH SOUTHWARD FORMING A
CLOSED LOW SOMEWHERE ALONG THE CENTRAL CALIFORNIA COAST. GEM/ECMWF
SOLUTION WOULD BRING A THREAT OF SHOWERS OR THUNDERSTORMS TO THE
SIERRA CASCADE CREST WHILE GFS WOULD KEEP FORECAST AREA DRY ON
WEDNESDAY. WILL KEEP SLIGHT THREAT OF THUNDERSTORMS IN FOR THE
SIERRA CASCADE RANGE ON WEDNESDAY AND THURSDAY FORECAST PERIOD UNTIL
MODELS COME INTO BETTER ALIGNMENT. OTHERWISE MAINLY FAIR SKIES
CONTINUE WITH NEAR NORMAL TEMPERATURES.
&&
.AVIATION...
VFR CONDITIONS EXPECTED NEXT 24 HOURS EXCEPT POSSIBLE MVFR CONDITIONS
WITH PATCHY LOW CLOUDS IN THE DELTA REGION WEST OF KSUU THROUGH
16Z. SOUTHWEST WINDS UP TO 20 KTS IN THE DELTA...WITH TAF SITES
GENERALLY LESS THAN 12 KTS. -DVC
&&
.STO WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1109 PM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE EAST COAST WILL GIVE WAY
TO LOW PRESSURE AND AN ASSOCIATED COLD FRONT LATE SATURDAY INTO
SATURDAY NIGHT. ANOTHER HIGH WILL BRING FAIR WEATHER SUNDAY INTO
WEDNESDAY. A COLD FRONT WILL MOVE THROUGH LATE WEDNESDAY INTO
EARLY THURSDAY...FOLLOWED AGAIN BY BUILDING HIGH PRESSURE FOR
FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
HIGH PRESSURE LOSING ITS GRIP ACROSS THE NORTHEAST...BUT LIGHT
EASTERLY WINDS CONTINUE.
FOG AND LOW CLOUDS ALREADY EVIDENT IN A FEW SPOTS...AND WILL
MAINTAIN PATCHY FOG IN THE GRIDS FOR THE OVERNIGHT. RAP INDICATING
FOG/POSSIBLE STRATUS IN TIME HEIGHTS.
TEMPS ON TRACK...AS LOWS WERE WEIGHTED MORE TOWARDS THE COOLER
MAV GUIDANCE WITH THE EXPECTATION OF GREATER RADIATIONAL COOLING
TAKING PLACE. LOWS FORECAST RANGE FROM UPPER 40S TO LOWER 50S FOR
INLAND AND RURAL LOCATIONS...TO THE MID 50 TO LOWER 60S ACROSS THE
REMAINDER OF THE AREA.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
THE PARENT LOW IS SIMILAR TO THE ONE ON THIS PAST TUESDAY BUT IT
IS A LITTLE FURTHER WEST. HIGH PRESSURE OFFSHORE IS NEARLY THE
SAME. THEREFORE...THERE IS LESS OF A PRESSURE GRADIENT THAN ON
TUESDAY. THIS WILL BE A KEY COMPONENT TO ASSESSING WIND AND
THEREBY SEVERE WEATHER POTENTIAL.
WINDS EARLY ON SATURDAY MORNING WILL BE INITIALLY LIGHT AND UNDER 10
KT. ACCOUNTING FOR SCATTERING OUT OF CLOUDS IN THE MORNING WITH ANY
PATCHY FOG DISSIPATING WITH DIURNAL WARMING. CAPE WILL BE INCREASING
DURING THIS TIME FRAME TO ABOUT 500-100 J/KG AS WELL AS SOME INCREASE
IN VORTICITY. SO THIS PVA AND INCREASING INSTABILITY WILL CREATE THE
FIRST CHANCE OF THUNDERSTORMS. THIS WILL BE WELL AHEAD OF THE COLD
FRONT IN THE FORM OF DISCRETE CELLS. THE MODELS ARE NOT REALLY
CAPTURING THIS POTENTIAL AHEAD OF THE FRONT AS OF YET WITH EXCEPTION
OF ECMWF AND SREF WHICH SHOWS AT LEAST A FEW HUNDREDTHS OF AN INCH
INTO FAR WESTERN PORTIONS OF THE AREA BY 18Z SAT. THE 12Z RUN OF THE
GFS ALSO HAS PROGRESSED FARTHER EAST WITH ITS QPF FIELD COMPARED TO
ITS PREVIOUS RUN IN BETWEEN 12-18Z. THE ONE LIMITING FACTOR WILL BE
THE MOISTURE AS DEWPOINTS WILL STILL BE IN THE LOWER 60S EARLY
SATURDAY MORNING BUT WITH A STEADY INCREASE THEREAFTER FROM
INCREASING LOW LEVEL SOUTH TO SOUTHWEST FLOW...THIS WILL AUGMENT
THETA-E ADVECTION IN THE LOW LEVELS AND THE RATE SPIKES INITIALLY
BETWEEN 12 AND 15Z WITH AT LEAST A 7K/3HR INCREASE FOR WESTERN
LOCATIONS AT 925MB. THE BEST POTENTIAL FOR SHOWERS AND THUNDERSTORMS
WILL SIMILAR THE 925MB THETA-E PROGRESSION OF AT LEAST 330K.
TAKING THIS INTO ACCOUNT...THE LIMITING MOISTURE FACTOR WILL KEEP
POPS LOW AT SLIGHT CHANCE AND GRADUALLY INCREASING CHANCES FROM WEST
TO EAST MID MORNING ONWARD AS THE TROUGH PUSHES CLOSER TO THE
REGION.
THE CAPE REALLY DROPS OFF ACROSS EASTERN COASTAL SECTIONS SO THEY
WILL HAVE MOST LIKELY DRY CONDITIONS WITH JUST A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON. WOULD NOT BE
SURPRISED IF THE WHOLE DAY IS DRY FOR EASTERN SECTIONS.
THE CAPE INCREASES TO AROUND 1000-1500 J/KG FOR THE LOWER HUDSON
VALLEY AND INTERIOR NORTHEAST NEW JERSEY AND BETWEEN 500-1000 J/KG
EAST ACROSS THE REST OF NORTHEAST NEW JERSEY...NEW YORK
CITY...WESTERN LONG ISLAND AND SOUTHWEST CONNECTICUT. THESE 500-1000
J/KG CAPE VALUES SPREAD MORE ACROSS LONG ISLAND SATURDAY NIGHT.
THE 0-6KM BULK SHEAR WILL BE MAINLY BETWEEN 30-40 KT AND THIS
COMBINED WITH THE CAPE WILL ALLOW FOR SOME THUNDERSTORMS TO BE
STRONG TO POSSIBLY SEVERE. LOW LEVEL JET AROUND 925MB VARIES FROM
AROUND 30KT IN GFS TO AROUND 40 KT IN NAM FOR SATURDAY NIGHT. AT
THIS POINT...THE GREATEST THREAT WITH ANY THUNDERSTORM WILL BE
WINDS. THE BEST FORCING OVERALL LOOKING AT THE MOISTURE FLUX IN THE
LOW LEVELS IS TO THE NORTH AND WEST IN THE AFTERNOON AND MAINLY
NORTH OF THE FORECAST REGION IN THE EVENING IN TERMS OF THE
CONVERGENCE.
FORECAST HIGH TEMPS FOR SATURDAY ARE A MAV/MET BLEND...RANGING FROM
NEAR IN THE LOWER 70S ACROSS EASTERN AREAS WITH COOLER ONSHORE FLOW
TO UPPER 70S AND LOWER 80S ACROSS WESTERN AREAS.
THE COLD FRONT MOVES THROUGH SATURDAY NIGHT...WITH A GENERAL
TIME FRAME OF 3-9Z FROM LOWER HUDSON VALLEY AND NORTHEAST NEW JERSEY
TOWARDS SOUTHEAST CONNECTICUT AND EASTERN LONG ISLAND. GUSTY WINDS
REMAIN THE THREAT THROUGH THE EVENING WITH SOME THUNDERSTORMS WITH
LOW LEVEL JET CORE MOVING ACROSS. THE UPPER LEVEL JET NEAR 250MB
WILL BE SOUTH SOUTHWESTERLY AND THE RIGHT REAR QUAD MOVES CLOSER TO
THE AREA. THE FORECAST TAKES INTO ACCOUNT THE SREF...WHICH IS CLOSER
TO THE ECMWF IN TERMS OF FRONT SPEED COMPARED TO THE GFS...WHICH IS
FASTER AND THE NAM...WHICH IS SLOWER.
SHOWERS AND THUNDERSTORMS WILL LOWER IN COVERAGE JUST BEHIND THE
FRONT LATE SATURDAY NIGHT FROM WEST TO EAST ACROSS THE REGION WITH
JET FORCING MOVING AWAY AS PARENT LOW MOVES FURTHER INTO SOUTHEAST
CANADA. USED FORECAST LOWS MORE FROM THE MET GUIDANCE LEANING MORE
TOWARDS WARMER TEMPS WITH ALL THE CLOUD COVER STILL AROUND FOR MUCH
OF THE NIGHT.
ALSO...THERE IS A HIGH RISK OF RIP CURRENTS AT THE ATLANTIC OCEAN
FACING BEACHES FOR SATURDAY.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
ANY RESIDUAL RAIN APPEARS TO BE E OF THE CWA BY 12Z SUN. SUNNY SKIES
SHOULD EMERGE...BUT DIURNAL CU IS EXPECTED TO DEVELOP BY EARLY AFTN.
A NW BREEZE CAN BE EXPECTED. TEMPS A BLEND OF THE MET/MAV.
A MID 1020S HIGH THEN BUILDS INTO THE SERN CONUS MON-TUE. THIS WILL
RESULT IN DRY WEATHER AND SEASONAL TEMPS.
12Z GFS HAS TRENDED TOWARDS THE SLOWER 00/12Z ECMWF WITH THE FROPA
FOR WED. HAVE SLOWED THE FCST ACCORDINGLY. THIS KEEPS WED MAINLY
DRY. THERE IS A HINT OF A -SHRA OR SPRINKLE WITH THE WAA
PATTERN...BUT THE PROB AND COVERAGE IS TOO LOW TO INCLUDE IN THE
FCST ATTM.
CHC SHRA WED NGT INTO THU MRNG WITH THE FRONT. MOISTURE IS LIMITED
WITH THE GOMEX SHUT OFF. TEMPS A FEW DEGREES WARMER WED...AND
REMAINS MILD OVERNIGHT WITH ONSHORE FLOW AND CLOUD COVER.
COOL AIR MASS BEHIND THE FRONT...COULD BE FALLING OR STEADY AFTN
TEMPS THU. DRY ON FRI WITH ANOTHER HIGH BUILDING IN.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE COAST WILL GIVE WAY TO
AN APPROACHING COLD FRONT LATE IN THE DAY ON SATURDAY.
SATELLITE SHOWS LOW STRATUS BEGINNING TO FORM ALONG THE CT
COAST...AND SHOULD EXPAND IN AREAL COVERAGE. OBS AT KJFK/KEWR ALSO
INDICATE A FEW LOW CLOUDS BEGINNING TO DEVELOP THERE AS WELL.
HELD THE COURSE FROM 00Z TAF...BUT TACTICAL AMENDMENTS MAY BE
NEEDED IF BKN LOW CIGS BECOME MORE WIDESPREAD THAN INDICATED.
CIGS/VSBY EXPECTED TO IMPROVE BY MID TO LATE MORNING SAT...WITH
GUSTY S WINDS DEVELOPING...MAXING OUT IN THE AFTERNOON AT 14-16
KT WITH GUSTS INTO THE LOWER 20S ACROSS THE NYC METRO TERMINALS.
HIGH CONFIDENCE IN SPARSE COVERAGE OF SHOWERS NORTH/WEST OF NYC
METRO SAT AFTERNOON. INCREASING CHANCE FOR SHOWERS/TSTMS AFTER 21Z
WITH APPROACH OF COLD FRONT. HEAVY RAIN WITH BRIEF MVFR OR LOWER
CONDS AND GUSTY WINDS POSSIBLE WITH THIS ACTIVITY.
OUTLOOK FOR 00Z SUNDAY THROUGH WED...
.SAT NIGHT...COLD FROPA PRECEDED BY LINE OF SHOWERS/TSTMS...WITH
MVFR OR LOWER CONDITIONS LIKELY. COLD FROPA TIMING 01Z-03Z AT NYC
METRO TERMINALS...FOLLOWED BY WIND SHIFT TO NW AND A FEW HOURS OF
GUSTY WINDS.
.SUNDAY...VFR. OCCASIONAL GUSTS INTO THE TEENS.
.SUNDAY NIGHT-WED...VFR.
&&
.MARINE...
SUB SCA CONDITIONS WILL REMAIN ACROSS THE WATERS THROUGH TONIGHT
AND THEN AN INCREASING SOUTHERLY FETCH WILL ALLOW FOR BUILDING SEAS
AND STRONGER WINDS ON SATURDAY. WITH SOME UNCERTAINTY ON
WAVEWATCH GUIDANCE AND HOW FAST THEY INCREASE WITH SOUTHERLY FLOW
AS WELL AS THE FREQUENCY OF THE GUSTS...HELD OFF ON SCA FOR NOW.
THESE SCA CONDITIONS WILL CONTINUE INTO SATURDAY NIGHT WITH FRONT
MOVING ACROSS.
BRISK WNW WINDS ON SUN BEHIND THE COLD FRONT...BUT SPEEDS APPEAR TO
BE MARGINAL FOR SCA CRITERIA. SEAS ON THE OCEAN HOWEVER EXPECTED TO
BREACH THE 5FT THRESHOLD...AND WILL SUBSIDE BLW SCA LVL SUN NGT.
HIGH PRES WILL BRING SUB SCA CONDITIONS MON-WED.
&&
.HYDROLOGY...
TOTAL QPF IS AROUND ONE TO THREE TENTHS OF AN INCH WITH LOCALLY
HIGHER AMOUNTS. THE SHOWERS AND THUNDERSTORMS WILL BE IN THE FORM
OF DISCRETE CELLS LATE SATURDAY MORNING INTO THE AFTERNOON AND IN
THE FORM OF A SQUALL LINE SATURDAY NIGHT. THE LINE SHOULD BE
RELATIVELY FAST MOVING...REALLY LIMITING THE AREAL EXTENT OF
FLOODING POTENTIAL. AT THIS POINT...THE ONLY FLOODING THREAT WOULD
BE WITH ANY REMARKABLY INTENSE CELL OR PART OF THE LINE WHICH
COULD EASILY LEAD TO SOME BRIEF MINOR POOR DRAINAGE URBAN
FLOODING. FLASH FLOOD POTENTIAL LOOKS TO BE LOW AT THE MOMENT.
WIDESPREAD SIGNIFICANT PCPN IS NOT EXPECTED SUN-FRI.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JMC/JM/PW
NEAR TERM...JM/PW
SHORT TERM...JM
LONG TERM...JMC
AVIATION...GOODMAN
MARINE...JMC/JM/PW
HYDROLOGY...JMC/JM
AREA FORECAST DISCUSSION
NWS NEW YORK NY
956 PM EDT FRI SEP 21 2012
.SYNOPSIS...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE EAST COAST WILL GIVE WAY
TO LOW PRESSURE AND AN ASSOCIATED COLD FRONT LATE SATURDAY INTO
SATURDAY NIGHT. ANOTHER HIGH WILL BRING FAIR WEATHER SUNDAY INTO
WEDNESDAY. A COLD FRONT WILL MOVE THROUGH LATE WEDNESDAY INTO
EARLY THURSDAY...FOLLOWED AGAIN BY BUILDING HIGH PRESSURE FOR
FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
HIGH PRESSURE LOSING ITS GRIP ACROSS THE NORTHEAST...BUT LIGHT
EASTERLY WINDS CONTINUE.
FOG ALREADY EVIDENT IN A FEW SPOTS...AND WILL MAINTAIN PATCHY FOG
IN THE GRIDS FOR THE OVERNIGHT. RAP INDICATING FOG/POSSIBLE
STRATUS IN TIME HEIGHTS.
TEMPS ON TRACK...AS LOWS WERE WEIGHTED MORE TOWARDS THE COOLER
MAV GUIDANCE WITH THE EXPECTATION OF GREATER RADIATIONAL COOLING
TAKING PLACE. LOWS FORECAST RANGE FROM UPPER 40S TO LOWER 50S FOR
INLAND AND RURAL LOCATIONS...TO THE MID 50 TO LOWER 60S ACROSS THE
REMAINDER OF THE AREA.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
THE PARENT LOW IS SIMILAR TO THE ONE ON THIS PAST TUESDAY BUT IT
IS A LITTLE FURTHER WEST. HIGH PRESSURE OFFSHORE IS NEARLY THE
SAME. THEREFORE...THERE IS LESS OF A PRESSURE GRADIENT THAN ON
TUESDAY. THIS WILL BE A KEY COMPONENT TO ASSESSING WIND AND
THEREBY SEVERE WEATHER POTENTIAL.
WINDS EARLY ON SATURDAY MORNING WILL BE INITIALLY LIGHT AND UNDER 10
KT. ACCOUNTING FOR SCATTERING OUT OF CLOUDS IN THE MORNING WITH ANY
PATCHY FOG DISSIPATING WITH DIURNAL WARMING. CAPE WILL BE INCREASING
DURING THIS TIME FRAME TO ABOUT 500-100 J/KG AS WELL AS SOME INCREASE
IN VORTICITY. SO THIS PVA AND INCREASING INSTABILITY WILL CREATE THE
FIRST CHANCE OF THUNDERSTORMS. THIS WILL BE WELL AHEAD OF THE COLD
FRONT IN THE FORM OF DISCRETE CELLS. THE MODELS ARE NOT REALLY
CAPTURING THIS POTENTIAL AHEAD OF THE FRONT AS OF YET WITH EXCEPTION
OF ECMWF AND SREF WHICH SHOWS AT LEAST A FEW HUNDREDTHS OF AN INCH
INTO FAR WESTERN PORTIONS OF THE AREA BY 18Z SAT. THE 12Z RUN OF THE
GFS ALSO HAS PROGRESSED FARTHER EAST WITH ITS QPF FIELD COMPARED TO
ITS PREVIOUS RUN IN BETWEEN 12-18Z. THE ONE LIMITING FACTOR WILL BE
THE MOISTURE AS DEWPOINTS WILL STILL BE IN THE LOWER 60S EARLY
SATURDAY MORNING BUT WITH A STEADY INCREASE THEREAFTER FROM
INCREASING LOW LEVEL SOUTH TO SOUTHWEST FLOW...THIS WILL AUGMENT
THETA-E ADVECTION IN THE LOW LEVELS AND THE RATE SPIKES INITIALLY
BETWEEN 12 AND 15Z WITH AT LEAST A 7K/3HR INCREASE FOR WESTERN
LOCATIONS AT 925MB. THE BEST POTENTIAL FOR SHOWERS AND THUNDERSTORMS
WILL SIMILAR THE 925MB THETA-E PROGRESSION OF AT LEAST 330K.
TAKING THIS INTO ACCOUNT...THE LIMITING MOISTURE FACTOR WILL KEEP
POPS LOW AT SLIGHT CHANCE AND GRADUALLY INCREASING CHANCES FROM WEST
TO EAST MID MORNING ONWARD AS THE TROUGH PUSHES CLOSER TO THE
REGION.
THE CAPE REALLY DROPS OFF ACROSS EASTERN COASTAL SECTIONS SO THEY
WILL HAVE MOST LIKELY DRY CONDITIONS WITH JUST A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON. WOULD NOT BE
SURPRISED IF THE WHOLE DAY IS DRY FOR EASTERN SECTIONS.
THE CAPE INCREASES TO AROUND 1000-1500 J/KG FOR THE LOWER HUDSON
VALLEY AND INTERIOR NORTHEAST NEW JERSEY AND BETWEEN 500-1000 J/KG
EAST ACROSS THE REST OF NORTHEAST NEW JERSEY...NEW YORK
CITY...WESTERN LONG ISLAND AND SOUTHWEST CONNECTICUT. THESE 500-1000
J/KG CAPE VALUES SPREAD MORE ACROSS LONG ISLAND SATURDAY NIGHT.
THE 0-6KM BULK SHEAR WILL BE MAINLY BETWEEN 30-40 KT AND THIS
COMBINED WITH THE CAPE WILL ALLOW FOR SOME THUNDERSTORMS TO BE
STRONG TO POSSIBLY SEVERE. LOW LEVEL JET AROUND 925MB VARIES FROM
AROUND 30KT IN GFS TO AROUND 40 KT IN NAM FOR SATURDAY NIGHT. AT
THIS POINT...THE GREATEST THREAT WITH ANY THUNDERSTORM WILL BE
WINDS. THE BEST FORCING OVERALL LOOKING AT THE MOISTURE FLUX IN THE
LOW LEVELS IS TO THE NORTH AND WEST IN THE AFTERNOON AND MAINLY
NORTH OF THE FORECAST REGION IN THE EVENING IN TERMS OF THE
CONVERGENCE.
FORECAST HIGH TEMPS FOR SATURDAY ARE A MAV/MET BLEND...RANGING FROM
NEAR IN THE LOWER 70S ACROSS EASTERN AREAS WITH COOLER ONSHORE FLOW
TO UPPER 70S AND LOWER 80S ACROSS WESTERN AREAS.
THE COLD FRONT MOVES THROUGH SATURDAY NIGHT...WITH A GENERAL
TIME FRAME OF 3-9Z FROM LOWER HUDSON VALLEY AND NORTHEAST NEW JERSEY
TOWARDS SOUTHEAST CONNECTICUT AND EASTERN LONG ISLAND. GUSTY WINDS
REMAIN THE THREAT THROUGH THE EVENING WITH SOME THUNDERSTORMS WITH
LOW LEVEL JET CORE MOVING ACROSS. THE UPPER LEVEL JET NEAR 250MB
WILL BE SOUTH SOUTHWESTERLY AND THE RIGHT REAR QUAD MOVES CLOSER TO
THE AREA. THE FORECAST TAKES INTO ACCOUNT THE SREF...WHICH IS CLOSER
TO THE ECMWF IN TERMS OF FRONT SPEED COMPARED TO THE GFS...WHICH IS
FASTER AND THE NAM...WHICH IS SLOWER.
SHOWERS AND THUNDERSTORMS WILL LOWER IN COVERAGE JUST BEHIND THE
FRONT LATE SATURDAY NIGHT FROM WEST TO EAST ACROSS THE REGION WITH
JET FORCING MOVING AWAY AS PARENT LOW MOVES FURTHER INTO SOUTHEAST
CANADA. USED FORECAST LOWS MORE FROM THE MET GUIDANCE LEANING MORE
TOWARDS WARMER TEMPS WITH ALL THE CLOUD COVER STILL AROUND FOR MUCH
OF THE NIGHT.
ALSO...THERE IS A HIGH RISK OF RIP CURRENTS AT THE ATLANTIC OCEAN
FACING BEACHES FOR SATURDAY.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
ANY RESIDUAL RAIN APPEARS TO BE E OF THE CWA BY 12Z SUN. SUNNY SKIES
SHOULD EMERGE...BUT DIURNAL CU IS EXPECTED TO DEVELOP BY EARLY AFTN.
A NW BREEZE CAN BE EXPECTED. TEMPS A BLEND OF THE MET/MAV.
A MID 1020S HIGH THEN BUILDS INTO THE SERN CONUS MON-TUE. THIS WILL
RESULT IN DRY WEATHER AND SEASONAL TEMPS.
12Z GFS HAS TRENDED TOWARDS THE SLOWER 00/12Z ECMWF WITH THE FROPA
FOR WED. HAVE SLOWED THE FCST ACCORDINGLY. THIS KEEPS WED MAINLY
DRY. THERE IS A HINT OF A -SHRA OR SPRINKLE WITH THE WAA
PATTERN...BUT THE PROB AND COVERAGE IS TOO LOW TO INCLUDE IN THE
FCST ATTM.
CHC SHRA WED NGT INTO THU MRNG WITH THE FRONT. MOISTURE IS LIMITED
WITH THE GOMEX SHUT OFF. TEMPS A FEW DEGREES WARMER WED...AND
REMAINS MILD OVERNIGHT WITH ONSHORE FLOW AND CLOUD COVER.
COOL AIR MASS BEHIND THE FRONT...COULD BE FALLING OR STEADY AFTN
TEMPS THU. DRY ON FRI WITH ANOTHER HIGH BUILDING IN.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE COAST WILL GIVE WAY TO
AN APPROACHING COLD FRONT LATE IN THE DAY ON SATURDAY.
MVFR CONDITIONS IN LOW STRATUS AND/OR MIST POSSIBLE AFTER 09Z SAT
WITH A LIGHT ONSHORE FLOW...ESPECIALLY OUTSIDE OF THE NYC
TERMINALS. KGON COULD BOUNCE BETWEEN MVFR AND IFR/LIFR LATE
TONIGHT AS IS OFTEN THE CASE AT THIS TIME OF YEAR WITH CLEAR SKIES
AND LIGHT ONSHORE FLOW.
CIGS/VSBY EXPECTED TO IMPROVE BY MID-MORNING SAT...WITH GUSTY S
WINDS DEVELOPING BY MID TO LATE MORNING...MAXING OUT AT 14-16 KT
WITH GUSTS INTO THE LOWER 20S ACROSS THE NYC METRO TERMINALS.
HIGH CONFIDENCE IN SPARSE COVERAGE OF SHOWERS NORTH/WEST OF NYC
METRO SAT AFTERNOON. INCREASING CHANCE FOR SHOWERS/TSTMS AFTER 21Z
WITH APPROACH OF COLD FRONT. HEAVY RAIN WITH BRIEF MVFR OR LOWER
CONDS AND GUSTY WINDS POSSIBLE WITH THIS ACTIVITY.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KJFK FCSTER COMMENTS: LOW CONFIDENCE IN 1000-2000 FT CIGS FROM
09Z-14Z. MEDIUM-HIGH CONFIDENCE IN S WIND GUSTS INTO THE LOWER 20S
FROM 17Z-23Z. MEDIUM CONFIDENCE ON SPARSE TSRA COVERAGE AFTER 22Z.
KLGA FCSTER COMMENTS: LOW CONFIDENCE IN 1000-2000 FT CIGS FROM
09Z-14Z. MEDIUM-HIGH CONFIDENCE IN S WIND GUSTS INTO THE LOWER 20S
FROM 18Z-23Z. MEDIUM CONFIDENCE ON SPARSE TSRA COVERAGE AFTER 22Z.
KEWR FCSTER COMMENTS: MEDIUM CONFIDENCE IN 1000-2000 FT CIGS FROM
09Z-14Z. MODERATE-HIGH CONFIDENCE IN S WIND GUSTS INTO THE LOWER
20S FROM 18Z-23Z. MEDIUM CONFIDENCE ON SPARSE TSRA COVERAGE
AFTER 21Z.
KTEB FCSTER COMMENTS: MEDIUM CONFIDENCE IN 1000-2000 FT CIGS AND
3-5SM VSBY FROM 09Z-14Z. HIGH CONFIDENCE IN S WIND GUSTS INTO THE
UPPER TEENS FROM 18Z-23Z. MEDIUM CONFIDENCE ON SPARSE TSRA
COVERAGE AFTER 21Z.
KHPN FCSTER COMMENTS: MEDIUM CONFIDENCE IN 1000-2000 FT CIGS AND
3-5SM VSBY FROM 09Z-14Z. HIGH CONFIDENCE IN S WIND GUSTS INTO THE
UPPER TEENS FROM 18Z-23Z. MEDIUM CONFIDENCE ON SPARSE TSRA
COVERAGE AFTER 21Z.
KISP FCSTER COMMENTS: MEDIUM CONFIDENCE IN 3-5SM VSBY FROM
09Z-14Z. HIGH CONFIDENCE IN S WIND GUSTS INTO THE UPPER TEENS FROM
18Z-23Z.
OUTLOOK FOR 00Z SUNDAY THROUGH WED...
.SAT NIGHT...COLD FROPA PRECEDED BY LINE OF SHOWERS/TSTMS...WITH
MVFR OR LOWER CONDITIONS LIKELY. COLD FROPA TIMING 01Z-03Z AT NYC
METRO TERMINALS...FOLLOWED BY WIND SHIFT TO NW AND A FEW HOURS OF
GUSTY WINDS.
.SUNDAY...VFR. OCCASIONAL GUSTS INTO THE TEENS.
.SUNDAY NIGHT-WED...VFR.
&&
.MARINE...
SUB SCA CONDITIONS WILL REMAIN ACROSS THE WATERS THROUGH TONIGHT
AND THEN AN INCREASING SOUTHERLY FETCH WILL ALLOW FOR BUILDING SEAS
AND STRONGER WINDS ON SATURDAY. WITH SOME UNCERTAINTY ON
WAVEWATCH GUIDANCE AND HOW FAST THEY INCREASE WITH SOUTHERLY FLOW
AS WELL AS THE FREQUENCY OF THE GUSTS...HELD OFF ON SCA FOR NOW.
THESE SCA CONDITIONS WILL CONTINUE INTO SATURDAY NIGHT WITH FRONT
MOVING ACROSS.
BRISK WNW WINDS ON SUN BEHIND THE COLD FRONT...BUT SPEEDS APPEAR TO
BE MARGINAL FOR SCA CRITERIA. SEAS ON THE OCEAN HOWEVER EXPECTED TO
BREACH THE 5FT THRESHOLD...AND WILL SUBSIDE BLW SCA LVL SUN NGT.
HIGH PRES WILL BRING SUB SCA CONDITIONS MON-WED.
&&
.HYDROLOGY...
TOTAL QPF IS AROUND ONE TO THREE TENTHS OF AN INCH WITH LOCALLY
HIGHER AMOUNTS. THE SHOWERS AND THUNDERSTORMS WILL BE IN THE FORM
OF DISCRETE CELLS LATE SATURDAY MORNING INTO THE AFTERNOON AND IN
THE FORM OF A SQUALL LINE SATURDAY NIGHT. THE LINE SHOULD BE
RELATIVELY FAST MOVING...REALLY LIMITING THE AREAL EXTENT OF
FLOODING POTENTIAL. AT THIS POINT...THE ONLY FLOODING THREAT WOULD
BE WITH ANY REMARKABLY INTENSE CELL OR PART OF THE LINE WHICH
COULD EASILY LEAD TO SOME BRIEF MINOR POOR DRAINAGE URBAN
FLOODING. FLASH FLOOD POTENTIAL LOOKS TO BE LOW AT THE MOMENT.
WIDESPREAD SIGNIFICANT PCPN IS NOT EXPECTED SUN-FRI.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JMC/JM/PW
NEAR TERM...JM/PW
SHORT TERM...JM
LONG TERM...JMC
AVIATION...GOODMAN
MARINE...JMC/JM/PW
HYDROLOGY...JMC/JM
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
736 PM EDT FRI SEP 21 2012
.SYNOPSIS...
HIGH PRESSURE LOCATED TO THE NORTHEAST WILL WEAKEN THROUGH TONIGHT.
THIS WILL ALLOW A COLD FRONT TO APPROACH FROM THE WEST AND CROSS
THE REGION ON SATURDAY INTO SATURDAY NIGHT. A LARGE HIGH PRESSURE
SYSTEM THEN BUILDS IN FROM THE WEST ON SUNDAY AND PERSISTS THROUGH
MIDWEEK. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA LATE WEDNESDAY
OR THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
NO BIG CHANGES TO TONIGHT. BASED ON LATEST HRRR AND COSPA AS WELL
AS RADAR RETURNS, WE DROPPED THE LOW CHANCES OF SHRAS GETTING
INTO THE POCONOS. TEMPS AND DEW POINTS ARE PRETTY MUCH SPOT ON,
WITH LESS SKY COVER WE DROPPED THEM SLIGHTLY FASTER DURG THE
EVENING, BUT MAINTAINED CURRENT MINS.
THIS SC SHOULD CLEAR THIS EVENING AS THE SUN SETS. DEWPOINTS HIGHER
TONIGHT THAN THIS PAST MORNING...ESPECIALLY E PA AND SOME DECOUPLING
INDICATED WITH A BL WIND UNDER 15 KT. SREF GUIDANCE AND TSECS OF
12Z/21 MODELS ARE GUIDING US TOWARD AN IFR/LIFR DEVELOPMENT OF ST
AND/OR FOG...AT LEAST IN THE INTERIOR AFTER 04Z. IF THERE IS A
DECK OF CLOUDS ABV 2000 FT...THAT WOULD MINIMIZE THE LIFR RISK.
FOR NOW...PATCHY FOG WILL BE IN THE GRIDS AND THINKING IS THE
THICKEST FOG WILL OCCUR IN E PA/FAR W NJ...NEAR AND WEST OF THE
DELAWARE.
WE MAY NEED TO RUN OUR FOG TOOLS AGAIN THIS EVENING AS I WASNT
SATISFIED WITH THE OUTPUT IN THE MID AFTN GRIDDED ISSUANCE.
TEMPS/WINDS/DEWPOINTS ARE 50 50 BLENDED 12Z/21 GFS/NAM GUIDANCE.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
AFTER MORNING FOG/ST CLEAR AROUND 14Z...A VERY FINE DAY IS UPCOMING...
PLENTY OF SS...GUSTY SSW WIND TO 20 MAYBE EVEN 25 MPH IN THE MID
AFTN AND 600J OF ML CAPE. THE APPROACHING CF THROUGH PA WILL HAVE
SHOWERS ALONG IT BUT THE CONVECTIVE INDICES DO NOT LOOK IMPRESSIVE
TO ME AND THINKING IS ONLY EMBEDDED ISO TSTMS LATE IN THE DAY IN E
PA. DUE TO SPEED SHEAR...THERE COULD BE A GUSTY TSTM TO 35 OR 40
KTS BUT ITS NOT SOMETHING THAT AM FAVORING ATTM.
TEMPS/WINDS/DEWPOINTS ARE BLENDED 21/12Z GFS/NAM MOS FAVORING THE
WARMER NAM VALUES IN SSW WARM SECTOR BL FLOW.
CONFIDENCE: AVERAGE
&&
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A CDFNT WILL BE CROSSING THE REGION AT THE START OF THE PD AND
WILL TRIGGER SHWRS AND SOME TSTMS. WE REMAIN IN A SLIGHT RISK FOR
SEVERE ON SATURDAY, BUT THE SET UP IS NOT LOOKING ALL THAT
PROMISING FOR A WIDESPREAD KIND OF EVENT. THE UPPER LEVEL JET IS
CENTERED PRETTY FAR OFF TO OUR NORTHWEST AND BETTER SITUATED WITH
THE STRONG MID LEVEL SHORTWAVE. SHEAR IS DECENT BUT STILL REMAINS
BEST OFF TO OUR NORTH. TIME OF DAY IS ALSO A FACTOR AS THE BRUNT
OF THE WX LOOKS TO OCCUR DURG THE EVE WELL AFTER PK HEATING. THERE
COULD BE SOME LCLY HVY RAIN, BUT OVERALL QPF VALUES ARE NOT ALL
THAT HIGH.
THE FRONT WILL CLEAR THE COAST BY DAYBREAK AND A LARGE AREA OF
HIGH PRESSURE OVER THE MIDSECTION OF THE COUNTRY WILL BEGIN TO
BUILD INTO THE ERN STATES. THIS HIGH WILL KEEP CONDS DRY THROUGH
ABOUT WEDNESDAY, AS THE HIGH MOVES EWD. BY LATER WED OR THU
ANOTHER CDFNT MAY APPROACH THE REGION.
TEMPS WILL START OFF BLO NRML BEHIND THE AFOREMENTIONED FROPA THEN
REBOUND TO NR SEASONAL BY MIDWEEK.
&&
.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
WITH THE 00Z TAFS, LOW CONFIDENCE FORECAST AS TO HOW IFR WE WILL
GO TOWARD MORNING. ON THE PLUS SIDE FOR FOG THE DEW POINTS ARE
HIGHER AND DID NOT DROP AS MUCH THIS AFTERNOON. SKIES ARE GOING TO
START CLEAR AND RADIATIONAL COOLING SHOULD HELP FORM THE
INVERSION. ON THE NEGATIVE SIDE WINDS JUST ABOVE THE SURFACE ARE
FORECAST TO INCREASE AT NIGHT. WE BELIEVE IT WILL NOT BE ENOUGH TO
OVERCOME THE EVENING DECOUPLING, BUT IT DOES ADD A LAYER OF
UNCERTAINTY. THE MODELS ARE FORECASTING SOME DEBRIS CLOUDINESS TO
COME IN OVERNIGHT. WE THINK MOST OF IT WILL REMAIN NORTHWEST OF
THE TERMINALS. LASTLY BUFKIT SOUNDINGS ARE SUGGESTING STRATUS OVER
FOG WITH THE MOST LIKELY COVERAGE AT KABE AND KRDG.
WE USED WHEN THE FOG FORMED THIS MORNING FOR AN ESTIMATED TIMING,
BUT BEYOND THAT NOT CONFIDENT IF AN IFR STRATUS DECK WOULD FORM
BEFORE THE FOG OR AS A RESULT OF THE FOG.
THE FOG AND ANY STRATUS SHOULD BURN OFF RATHER QUICKLY SATURDAY
MORNING AS WINDS JUST ALOFT SHOULD MIX RELATIVELY EARLY AND HELP
DISPERSE AND DISSIPATE THEM. THEN MOST OF SATURDAY DAY SHOULD BE
VFR WITH SOME SCATTERED CUMULUS CLOUDS AND AN INCREASING SOUTH TO
SOUTHWEST WIND. WE DID NOT CARRY FREQUENT GUSTS WITH THIS PACKAGE,
ALTHOUGH A FEW GUSTS OVER 20 KNOTS SHOULD OCCUR. NO SEA BREEZE IS
ANTICIPATED TO REACH THE TERMINALS. LATE SATURDAY THERE IS A
CHANCE FOR THUNDERSTORMS. BASED ON FORECAST INSTABILITY AND
TIMING, LIKELY A HIGHER CHANCE AT THE NORTHWEST TERMINALS AND
AIRPORTS THAN SOUTHEAST. IT LOOKS AS THOUGH MOST TERMINALS IF
THUNDER OCCURS, WOULD BE AFFECTED FOR AN HOUR OR LESS.
THE KPHL TAF IS ESTIMATING A CFP AT 04Z.
OUTLOOK...
SATURDAY OVERNIGHT...IMPROVING CONDITIONS BY DAYBREAK.
SUNDAY THROUGH WEDNESDAY...THE COLD FRONT MOVES OFFSHORE EARLY ON
SUNDAY AND CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR FROM WEST TO
EAST. HIGH PRESSURE THEN BUILDS IN KEEPING GOOD FLYING CONDITIONS
ACROSS THE TERMINALS THROUGH THE MIDDLE OF THE WEEK.
&&
.MARINE...
NO HEADLINES THROUGH AT LEAST MIDDAY SATURDAY.
CONSIDERABLE UNCERTAINTY REGARDING EXCEEDING SCA THRESHOLD FROM
MID AFTERNOON SATURDAY INTO SAT NIGHT. WE HAVE GRIDDED SCA
CONDITIONS IN THE ATLC WATERS BUT THIS COULD BE SLIGHTLY OVERDONE.
12Z/21 NAM WAS MORE ROBUST THAN THE GFS/ECMWF.
ESE WIND G UNDER 15 KTS NOW BECOMING MORE SSE DURING THE NIGHT AND
THE SSW SATURDAY. G SAT AFTERNOON MAY NUDGE 25 KTS AND ATLC SEAS
MAY REACH 5 FT IN THE AFTN.
OUTLOOK...
A COLD FRONT WILL MOVE THROUGH SATURDAY NIGHT INTO EARLY SUNDAY,
BRINGING SHOWERS AND THUNDERSTORMS THROUGH THE AREA WATERS. SEAS
WILL LIKELY BE IN THE 5-6 FT RANGE SAT NIGHT ON THE OCEAN FRONT.
AS THE FRONT MOVES THROUGH, THE WINDS WILL TURN TO THE WEST AND
BECOME QUITE GUSTY, AROUND 25 KNOTS, WHICH WILL AID IN KEEPING THE
SEAS AT OR ABOVE 5 FEET THROUGH MUCH OF SUNDAY. SEAS SHOULD START
TO SUBSIDE BY LATE SUNDAY AFTERNOON OR EVENING. A SCA WILL LIKELY
BE NEEDED DURG THIS TIME PD.
HIGH PRESSURE BUILDS IN ON SUNDAY AND PERSISTS THROUGH THE MIDWEEK
PERIOD, KEEPING WINDS AND WAVES BELOW SMALL CRAFT ADVISORY CRITERIA.
&&
.RIP CURRENTS...
APPARENTLY A COUPLE OF RESCUES ALONG THE NJ COAST THIS AFTN WITH AN
E SWELL OF 3 FT VARYING BETWEEN 6 AND 12 SECONDS. WE UPGRADED THE
SRF RISK TO MODERATE FOR NJ.
SATURDAY AND SUNDAY...A MODERATE RISK FOR DANGEROUS RIP CURRENTS
SHOULD PREVAIL WITH A 10 TO 12 SECOND PERIOD 3 TO 4 FT E SWELL.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...NIERENBERG
NEAR TERM...DRAG/GIGI
SHORT TERM...DRAG
LONG TERM...NIERENBERG
AVIATION...GIGI/JACKSON/NIERENBERG
MARINE...DRAG/NIERENBERG
RIP CURRENTS...
AREA FORECAST DISCUSSION
NWS MIAMI FL
1009 PM EDT FRI SEP 21 2012
.UPDATE...
LATEST RADAR RETURNS AND SATELLITE IMAGERY INDICATE MOSTLY CLOUDY
SKIES ACROSS THE REGION AND WIDELY DISPERSED SHOWERS AND ISOLATED
THUNDERSTORMS...WITH MOST OF THE SHOWERS REMAINING ACROSS THE
WESTERN HALF OF THE PENINSULA AND GULF WATERS. ALTHOUGH THERE IS
SPARSE ACTIVITY ACROSS THE ATLANTIC WATERS AND THE EASTERN HALF OF
THE PENINSULA...REDEVELOPMENT OF CONVECTION IS POSSIBLE ACROSS THE CWA.
GIVEN THE MID TO UPPER LEVEL TROUGH OVER THE GULF WITH RECENT
GUIDANCE INDICATING EMBEDDED SHORT WAVES POSSIBLE IN THE PROXIMITY
OF SOUTH FLORIDA...NEW CONVECTION IS POSSIBLE THE REMAINING
EVENING HOURS AND OVER NIGHT. IN ADDITION THE OOZ SOUNDING
INDICATED LINGERING INSTABILITY AND LOW LEVEL LAPSE RATES THAT
INDICATE THE POTENTIAL FOR ADDITIONAL CONVECTION. THEREFORE
MAINTAINING A CHANCE OF SHOWERS AND THUNDERSTORMS CWA WIDE THIS
EVENING AND OVER NIGHT.
60
&&
.PREV DISCUSSION... /ISSUED 738 PM EDT FRI SEP 21 2012/
AVIATION...LIGHT RAIN CONTINUES TO IMPACT KAPF AND KPBI BUT WITH
VFR CONDITIONS. THE LIGHT RAIN WILL TAPER OFF THERE OVER THE NEXT
1-2 HR. THEN IT IS A CHALLENGING FORECAST AS TO WHAT TRANSPIRES
OVERNIGHT. HAVE MAINTAINED VCSH THEN VCTS LATE TONIGHT FOR THE EAST
COAST AS CONVECTION COULD RE-DEVELOP OVER THE ATLANTIC AND MOVE
ONSHORE. IT COULD BE A VERY WET DAY ON SATURDAY WITH POTENTIAL FOR
NUMEROUS SHRA/TSRA, SOME WITH HEAVY RAINS. HAVE PLACED PROB30 OF
MVFR CONDITIONS ALL EAST COAST SITES FROM 14-20Z SAT...AND WE CAN
TREND THIS WORSE AS TIME APPROACHES. IFR AND LIFR IS A POSSIBILITY
AT TIMES ON SATURDAY, ESPECIALLY EAST COAST TERMINALS. KAPF HAS A
LESSER CHANCE OF IMPACTS, SO MAINTAINED VCTS THERE FOR SATURDAY AT
THIS TIME. /GREGORIA
PREV DISCUSSION... /ISSUED 242 PM EDT FRI SEP 21 2012/
SHORT TERM...(TONIGHT-SUNDAY NIGHT)
THE LATEST RUC13 400 MB ANALYSIS AND WATER VAPOR LOOP SHOWED THE
LOCAL AREA UNDER MOIST SOUTHWEST UPPER FLOW AHEAD OF A LARGE SCALE
UPPER TROUGH CENTERED OVER MUCH OF THE COUNTRY. SEVERAL WEAK
PIECES OF ENERGY TRANSLATING NORTHEAST OVER THE STATE WITHIN THIS
SW UPPER FLOW COMBINED WITH THE OLD FRONTAL BOUNDARY AT THE
SURFACE THAT IS FORECAST TO SLOWLY SHIFT SOUTH INTO THE LOCAL AREA
THIS WEEKEND WILL KEEP THE RAIN CHANCES IN THE FORECAST. FOR THIS
EVENING...THE LATEST HRRR GUIDANCE INDICATES SCATTERED STORMS
SETTING UP FROM NAPLES TO THE LAKE REGION...WHICH IS VERY SIMILAR
TO YESTERDAY AFTERNOON/EVENING. ON SATURDAY...THE LATEST GFS
SOLUTION INDICATES A SURFACE WAVE DEVELOPING ALONG THIS BOUNDARY
AS A WEAK VORT MAX LIFTS NORTHEAST OVER THE AREA THROUGH THE DAY.
THIS COMBINED WITH PLENTY OF DEEP LAYER MOISTURE COULD LEAD TO AN
ENHANCED PERIOD OF RAINFALL TOMORROW ONCE AGAIN TOMORROW. IF THIS
DOES OCCUR...WEAK LOW LEVEL FLOW COULD TRANSLATE TO FLOODING
CONCERNS DEPENDING ON WHERE THE BULK OF THE ACTIVITY BECOMES
CONCENTRATED.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...WHATS LEFT OF THE PREVIOUSLY
DISCUSSED BOUNDARY OR DEEP LAYER MOISTURE AXIS IN PLACE ACROSS S FL
IS FORECAST TO SLIGHTLY SHIFT FARTHER SOUTH AS ANOTHER REINFORCING
COLD FRONT SURGES SOUTH INTO THE REGION AND THE LARGE SCALE UPPER
TROUGH BEGINS TO SHIFT EAST. THE GFS APPEARS TO BE SLIGHTLY FASTER
THAN THE ECMWF AND NAM SOLUTIONS AND BEGINS TO INTRODUCE SOME DRIER
AIR AROUND THE LAKE REGION COME SUNDAY NIGHT INTO MONDAY. 85/AG
LONG TERM...(MONDAY-THURSDAY)
THE UPPER TROUGH BEGINS TO SHIFT SLOWLY EAST AS THE UPPER RIDGE
OVER THE ROCKIES BEGINS TO BREAK DOWN AS ANOTHER MID LEVEL TROUGH
MOVES FROM THE PACIFIC NORTHWEST INTO THE ROCKIES. SOME SLIGHT
DRYING /DECREASE MAY OCCUR INITIALLY AS DRIER AIR FILTERS IN THE
THE NW BUT THE MODELS HINT AT AN UPPER LOW DEVELOPING OVER THE
GULF AND MOVING NE ACROSS THE FLA PENINSULA IN THE LATTER PERIODS.
WILL STAY CLOSE TO EXTENDED GUIDANCE AND SEE WHAT DEVELOPS. JR
MARINE...
LIGHT EASTERLY WINDS WILL PERSIST THROUGH THE WEEKEND
WITH SEAS REMAINING AROUND NORMAL. A STALLED FRONTAL BOUNDARY
COMBINED WITH AN UPPER TROUGH OF LOW PRESSURE WILL KEEP THE
RAINFALL CHANCES ELEVATED THROUGH THE WEEKEND. WINDS AND SEAS CAN
LOCALLY BECOME HIGHER IN AND AROUND ANY HEAVY SHOWERS OR STORMS.
FIRE WEATHER...
NO CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 75 83 76 84 / 50 70 60 40
FORT LAUDERDALE 75 85 74 84 / 50 70 60 40
MIAMI 75 86 74 86 / 50 70 60 40
NAPLES 75 86 75 84 / 50 50 50 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...60/BD
AVIATION/RADAR...57/DG
AREA FORECAST DISCUSSION
NWS MIAMI FL
738 PM EDT FRI SEP 21 2012
.AVIATION...LIGHT RAIN CONTINUES TO IMPACT KAPF AND KPBI BUT WITH
VFR CONDITIONS. THE LIGHT RAIN WILL TAPER OFF THERE OVER THE NEXT
1-2 HR. THEN IT IS A CHALLENGING FORECAST AS TO WHAT TRANSPIRES
OVERNIGHT. HAVE MAINTAINED VCSH THEN VCTS LATE TONIGHT FOR THE EAST
COAST AS CONVECTION COULD RE-DEVELOP OVER THE ATLANTIC AND MOVE
ONSHORE. IT COULD BE A VERY WET DAY ON SATURDAY WITH POTENTIAL FOR
NUMEROUS SHRA/TSRA, SOME WITH HEAVY RAINS. HAVE PLACED PROB30 OF
MVFR CONDITIONS ALL EAST COAST SITES FROM 14-20Z SAT...AND WE CAN
TREND THIS WORSE AS TIME APPROACHES. IFR AND LIFR IS A POSSIBILITY
AT TIMES ON SATURDAY, ESPECIALLY EAST COAST TERMINALS. KAPF HAS A
LESSER CHANCE OF IMPACTS, SO MAINTAINED VCTS THERE FOR SATURDAY AT
THIS TIME. /GREGORIA
&&
.PREV DISCUSSION... /ISSUED 242 PM EDT FRI SEP 21 2012/
SHORT TERM...(TONIGHT-SUNDAY NIGHT)
THE LATEST RUC13 400 MB ANALYSIS AND WATER VAPOR LOOP SHOWED THE
LOCAL AREA UNDER MOIST SOUTHWEST UPPER FLOW AHEAD OF A LARGE SCALE
UPPER TROUGH CENTERED OVER MUCH OF THE COUNTRY. SEVERAL WEAK
PIECES OF ENERGY TRANSLATING NORTHEAST OVER THE STATE WITHIN THIS
SW UPPER FLOW COMBINED WITH THE OLD FRONTAL BOUNDARY AT THE
SURFACE THAT IS FORECAST TO SLOWLY SHIFT SOUTH INTO THE LOCAL AREA
THIS WEEKEND WILL KEEP THE RAIN CHANCES IN THE FORECAST. FOR THIS
EVENING...THE LATEST HRRR GUIDANCE INDICATES SCATTERED STORMS
SETTING UP FROM NAPLES TO THE LAKE REGION...WHICH IS VERY SIMILAR
TO YESTERDAY AFTERNOON/EVENING. ON SATURDAY...THE LATEST GFS
SOLUTION INDICATES A SURFACE WAVE DEVELOPING ALONG THIS BOUNDARY
AS A WEAK VORT MAX LIFTS NORTHEAST OVER THE AREA THROUGH THE DAY.
THIS COMBINED WITH PLENTY OF DEEP LAYER MOISTURE COULD LEAD TO AN
ENHANCED PERIOD OF RAINFALL TOMORROW ONCE AGAIN TOMORROW. IF THIS
DOES OCCUR...WEAK LOW LEVEL FLOW COULD TRANSLATE TO FLOODING
CONCERNS DEPENDING ON WHERE THE BULK OF THE ACTIVITY BECOMES
CONCENTRATED.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...WHATS LEFT OF THE PREVIOUSLY
DISCUSSED BOUNDARY OR DEEP LAYER MOISTURE AXIS IN PLACE ACROSS S FL
IS FORECAST TO SLIGHTLY SHIFT FARTHER SOUTH AS ANOTHER REINFORCING
COLD FRONT SURGES SOUTH INTO THE REGION AND THE LARGE SCALE UPPER
TROUGH BEGINS TO SHIFT EAST. THE GFS APPEARS TO BE SLIGHTLY FASTER
THAN THE ECMWF AND NAM SOLUTIONS AND BEGINS TO INTRODUCE SOME DRIER
AIR AROUND THE LAKE REGION COME SUNDAY NIGHT INTO MONDAY. 85/AG
LONG TERM...(MONDAY-THURSDAY)
THE UPPER TROUGH BEGINS TO SHIFT SLOWLY EAST AS THE UPPER RIDGE
OVER THE ROCKIES BEGINS TO BREAK DOWN AS ANOTHER MID LEVEL TROUGH
MOVES FROM THE PACIFIC NORTHWEST INTO THE ROCKIES. SOME SLIGHT
DRYING /DECREASE MAY OCCUR INITIALLY AS DRIER AIR FILTERS IN THE
THE NW BUT THE MODELS HINT AT AN UPPER LOW DEVELOPING OVER THE
GULF AND MOVING NE ACROSS THE FLA PENINSULA IN THE LATTER PERIODS.
WILL STAY CLOSE TO EXTENDED GUIDANCE AND SEE WHAT DEVELOPS. JR
MARINE...
LIGHT EASTERLY WINDS WILL PERSIST THROUGH THE WEEKEND
WITH SEAS REMAINING AROUND NORMAL. A STALLED FRONTAL BOUNDARY
COMBINED WITH AN UPPER TROUGH OF LOW PRESSURE WILL KEEP THE
RAINFALL CHANCES ELEVATED THROUGH THE WEEKEND. WINDS AND SEAS CAN
LOCALLY BECOME HIGHER IN AND AROUND ANY HEAVY SHOWERS OR STORMS.
FIRE WEATHER...
NO CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 75 83 76 84 / 50 70 60 40
FORT LAUDERDALE 75 85 74 84 / 50 70 60 40
MIAMI 75 86 74 86 / 50 70 60 40
NAPLES 75 86 75 84 / 50 50 50 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1005 PM CDT FRI SEP 21 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
.DISCUSSION...
348 PM CDT
COOL THROUGH THE WEEKEND THEN TEMPERATURES MODERATE FIRST PART OF
NEXT WEEK. A SHORT BREAK IN THREAT OF RAIN THIS EVENING THEN
CHANCES RETURN OVERNIGHT THROUGH SAT MORNING.
MULTIPLE MINOR SHORT WAVES IN THE UPPER FLOW TURNING FROM SSE TO
SE AS THEY CROSS THE UPPER MIDWEST AND THEN SE TO ESE AS THEY
ROTATE ACROSS THE MID MS VALLEY AND THE WESTERN GREAT LAKES INTO
THE BASE OF THE UPPER TROUGH THE REST OF TODAY AND THIS EVENING.
FURTHER UPSTREAM OVER SOUTHERN MANITOBA IS A STRONGER SHORT WAVE
PROGGED TO REACH SOUTHERN WI BY 12Z SAT. AS THIS DISTURBANCE
APPROACHES LATE TONIGHT A CHANCE OF RAIN RETURNS
OVERNIGHT...ENDING MIDDAY WITH THIS SHORT WAVE TROUGH PROGGED TO
CONTINUE ON TO NORTHERN IND BY 18Z SAT. HIGHEST CHANCES WILL BE
ACROSS THE NE 1/2 OF THE FORECAST AREA...ALONG AND N OF THE
PROJECTED PATH OF THE VORT MAX.
IN THE WAKE OF THE SHORT WAVE/WAVES MOVING ACROSS THE AREA TODAY
WEAK LOW LEVEL COLD AIR ADVECTION TO TAKE PLACE. THIS...COMBINED
WITH EXPECTED SHOWERS AND EXTENSIVE CLOUDINESS...WILL KEEP
TEMPERATURES DURING SAT LIMITED TO THE UPPER 50S AND LOWER 60S.
WITH THE PASSAGE OF THE STRONGER SHORT WAVE DURING SAT MORNING
STRONGER COLD AIR ADVECTION TO TAKE PLACE WITH 850HPA
TEMPERATURES DROPPING TO AROUND 0C FOR THE AFTERNOON. DESPITE THE
COLD AIR ADVECTION SURFACE HEATING IS EXPECTED TO MITIGATE THE
COOLING AS CLOUDS CLEAR DURING THE DAY IN THE WAKE OF THE SHORT
WAVE.
A HIGH PRESSURE RIDGE IS TO BE BUILDING FROM THE NORTHERN PLAINS
ACROSS THE MO RIVER VALLEY DURING THE DAY SAT AND THE UPPER AND
MID MS VALLEY AND LOWER OH VALLEY DURING SAT NIGHT. CLEAR
SKIES...DEW POINTS IN THE MID 20S TO LOWER 30S...AND LACK OF
BOUNDARY LAYER MIXING AS SURFACE WINDS BECOME NIL ARE EXPECTED TO
LEAD TO SAT NIGHT LOWS IN THE LOWER AND MID 30S ACROSS MUCH OF
THE LOCAL FORECAST AREA. FROST A GOOD POSSIBILITY ACROSS THE W
AND SW PORTIONS OF THE FORECAST AREA...CLOSEST TO THE SURFACE
RIDGE AXIS...OVERNIGHT SAT AND EARLY SUN MORNING.
YET ANOTHER SHORT WAVE IS SHOWN BY MODELS DROPPING OVER THE UPPER
MIDWEST AND THE WESTERN GREAT LAKES DURING SUN. HOWEVER...WITH A
VERY DRY AIR MASS IN PLACE POPS ONLY IN THE SINGLE DIGITS. EVEN
CLOUDS WILL BE HARD TO COME BY WITH JUST SOME CIRRUS ASSOCIATED
WITH THE JET MAX MOVING OVERHEAD. WITH THE UPPER TROUGH
BROADENING OVER THE REGION AND THE CENTER OF THE CENTER OF THE
LARGE SCALE UPPER CYCLONE REESTABLISHING ITSELF OVER SOUTHERN
HUDSON BAY AND NW QUEBEC BY MON MORNING THE MID LATITUDE UPPER
FLOW BACKS TO OUT OF THE WNW. WITH THE UPPER LOW FURTHER NORTH
DISTURBANCES ROTATING AROUND IT WILL TRACK OVER THE NORTH WOODS
AND THE NORTHERN GREAT LAKES KEEPING CHANCES OF PRECIPITATION LOW
THROUGH MON NIGHT.
HOWEVER...A COLD FRONT IS PROGGED TO SLIP SE ACROSS THE LOCAL
AREA TUE AND TUE NIGHT BEFORE BECOMING STATIONARY FROM NE MO
ACROSS CENTRAL IL TO NORTHERN IND BY WED MORNING. INCREASING FLOW
FROM THE CENTRAL PLAINS ENE ACROSS THE MID MS VALLEY WILL RESULT
IN INCREASING WARM AIR ADVECTION AS WELL AS MID AND LOWER LEVEL
MOISTURE TRANSPORT INTO THE AREA WITH CHANCES OF SHOWERS AND
THUNDERSTORMS...MAINLY FOR THE N 1/2 TO 3/4 OF THE LOCAL FORECAST
AREA TUE THROUGH WED BEFORE A STRONG SHORT WAVE DROPPING ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES PUSHES THE SURFACE FRONT
FURTHER TO THE S AND ANOTHER LARGE SURFACE ANTICYCLONE BUILDS OVER
THE UPPER MIDWEST AND THE GREAT LAKES DURING WED AND WED NIGHT.
WED NIGHT THROUGH FRI WILL HAVE LOW POPS AS THE HIGH PRESSURE WILL
DOMINATE THE WEATHER OVER THE REGION...CONTINUING TO FEED COOL DRY
AIR ACROSS THE AREA.
TRS
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 03Z...
* VARIABLE WIND DIRECTION THIS EVENING.
* POTENTIAL FOR SOME PATCHY SHALLOW FOG.
* SHOWERS DEVELOPING AGAIN LATE...WITH PATCHY MVFR CONDITIONS
POSSIBLE.
* STRONG NORTHWEST WINDS GUSTING 25-30 KTS SATURDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
LOW PRESSURE WAS MOVING ACROSS CENTRAL ILLINOIS LATE THIS
AFTERNOON...AND WILL MOVE QUICKLY EAST INTO INDIANA THIS EVENING.
LIGHT RAIN CURRENTLY OVER NORTHERN IL/LAKE MICHIGAN WILL MOVE OFF
TO THE EAST BY MID-EVENING AS THE LOW AND ITS ASSOCIATED MID-LEVEL
DISTURBANCE DEPART. SURFACE WINDS HAD BECOME NORTHEAST AND
INCREASED A BIT IN RESPONSE TO THE DEEPENING OF THE LOW...BUT WERE
BEGINNING TO BECOME MORE LIGHT/VARIABLE WITHIN AN AREA OF WEAK
HIGH PRESSURE OVER FAR NORTHERN IL. WIND DIRECTION WILL CONTINUE
TO BE RATHER VARIABLE THROUGH THE MID-EVENING HOURS...BEFORE
BECOMING MORE WESTERLY AHEAD OF ANOTHER COLD FRONT MOVING RAPIDLY
SOUTHEAST ACROSS THE UPPER MIDWEST. SPEEDS SHOULD GENERALLY BE
LESS THAN 10 KTS HOWEVER UNTIL THE FRONT APPROACHES EARLY
SATURDAY. OTHER THAN SOME PATCHY FEW-SCT MVFR LAYER CLOUDS WITH
THE SHOWERS EARLY THIS EVENING...VFR CONDITIONS ARE EXPECTED WITH
BKN-OVC MID DECK AROUND 8 KFT. SHOULD THIS DECK ERODE THERE COULD
BE THE POTENTIAL FOR SOME SHALLOW FOG TO DEVELOP GIVEN LIGHT WINDS
AND MOIST GROUND...THOUGH THE MID DECK LOOKS TO PREVAIL THROUGH
THE EVENING.
STRONG COLD FRONT MOVES THROUGH THE AREA EARLY SATURDAY
MORNING...SHIFTING WINDS TO THE NORTHWEST 310-330 DEGREES WITH
INCREASINGLY GUSTY CONDITIONS. FORECAST SOUNDINGS INDICATE GUST
POTENTIAL IN THE 25-30 KT RANGE AT TIMES WITH SUSTAINED SPEEDS
15-20 KTS. STRONG MID-LEVEL DISTURBANCE SHOULD SUPPORT SHOWERS
DURING THE MORNING...WHICH MAY PRODUCE MVFR CIG/VIS CONDITIONS.
STRATOCU CIGS SHOULD RISE TO VFR BY EARLY AFTERNOON HOWEVER AS
MUCH DRIER AIR SPREADS IN.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 03Z...
* MEDIUM-HIGH CONFIDENCE IN WIND TRENDS TONIGHT.
* MEDIUM CONFIDENCE IN TIMING OF PRECIP/CIGS THROUGH PERIOD.
* HIGH CONFIDENCE IN WIND TRENDS SATURDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR. DIMINISHING WEST-NORTHWEST WINDS.
MONDAY...VFR.
TUESDAY...VFR. CHC SHRA.
WEDNESDAY...VFR.
THURSDAY...VFR.
RATZER
&&
.MARINE...
230 PM CDT
LOW PRESSURE OVER THE UPPER GREAT LAKES WILL TRACK NORTHEAST
TOWARD HUDSON BAY OVERNIGHT TONIGHT AND THEN RAPIDLY DEEPEN
TOMORROW AS STRONG HIGH PRESSURE BUILDS ACROSS THE NORTHERN
PLAINS. A SERIES OF MID LEVEL IMPULSES WILL BRING REINFORCING
SHOTS OF COLD AIR OVER THE WESTERN GREAT LAKES TOMORROW. THE
RESULTANT STRONG COLD ADVECTION WILL LEAD TO RAPIDLY
STRENGTHENING NORTHERLY WINDS TOMORROW...LIKELY REACHING GALE
FORCE DURING THE AFTERNOON HOURS. THE PRESSURE GRADIENT AND COLD
ADVECTION WILL BE STRONGEST OVER THE FAR NORTHERN PORTIONS OF THE
LAKE...SO HAVE HOISTED A GALE WARNING FOR THE NORTHERN ONE-THIRD
OF THE LAKE. THE WINDOW OF OPPORTUNITY FOR THE STRONGEST WINDS
WILL BE DURING THE AFTERNOON AND EVENING HOURS WHEN HIGH PRESSURE
SPREADING INTO THE WESTERN GREAT LAKES SHOULD HELP ALLOW WINDS TO
SUBSIDE BELOW GALE FORCE. FOR THE SOUTHERN PORTIONS OF THE
LAKE...WINDS AND WAVES SHOULD QUICKLY RISE TO SMALL CRAFT
ADVISORY LEVELS TOMORROW AS WELL...WITH THE INDIANA WATERS
REACHING SMALL CRAFT ADVISORY LEVELS SOONER THAN THE ILLINOIS
WATERS...AND LINGERING LONGER...INTO MONDAY MORNING DUE TO THE
GENERALLY NORTHERLY FETCH SETTING UP OVER THE LAKE. BY MONDAY
AFTERNOON...ANOTHER DEEPENING LOW TRACKING JUST NORTH OF THE
GREAT LAKES MAY POSSIBLY BRING ANOTHER BRIEF PERIOD OF
SOUTHWESTERLY GALES TO THE FAR NORTHERN PORTION OF THE LAKE...
BUT WILL NOT ISSUE ANY HEADLINES AT THIS TIME SINCE THE STRENGTH
OF THE WINDS WILL BE HIGHLY DEPENDENT ON THE EXACT TRACK OF THE
LOW.
THE OTHER CONCERN FOR LAKE MICHIGAN WILL BE WATERSPOUT POTENTIAL.
LAKE SFC WATER TEMPERATURES REMAIN UNUSUALLY HIGH...WITH A
TEMPERATURE OF 17C AT THE NORTH BUOY AND 20C AT THE SOUTH BUOY
THIS AFTERNOON. WHEN THE MUCH COOLER AIR PLUNGES OVER LAKE
MICHIGAN...LAKE SFC TO 850MB DELTA-T VALUES WILL REACH AS HIGH AS
22-23C...INDICATIVE OF A VERY UNSTABLE ENVIRONMENT OVER LAKE
MICHIGAN. WHILE CONVERGENCE BOUNDARIES ARE NOT LIKELY OVER THE
LAKE...WATERSPOUT POTENTIAL WILL REMAIN HIGH DUE TO LAKE EFFECT
RAIN SHOWERS AND DEEP LAYER CONVECTIVE CLOUD DEVELOPMENT.
CONDITIONS WILL BE CONDUCIVE TO WATERSPOUTS FROM THIS EVENING
THROUGH MONDAY EVENING...ESPECIALLY FOR THE NORTHERN AND EASTERN
PORTIONS OF THE LAKE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
849 PM CDT FRI SEP 21 2012
.DISCUSSION...
ISSUED 842 PM CDT FRI SEP 21 2012
SURFACE LOW LOCATED JUST NORTHWEST OF EFFINGHAM...TRACKING ESE
WITH THE ATTENDANT COLD FRONT. SCATTERED CONVECTION CONTINUES
TO SLOWLY WEAKEN ALTHOUGH WE ARE STILL SEEING SOME WEAK
CIRCULATIONS ALONG THE WARM FRONT OVER PARTS OF SE IL FROM TIME
TO TIME. EXPECT THE WEAKENING TRENDS TO CONTINUE. NORTH OF THE
COLD BOUNDARY...WINDS WERE OUT OF THE NORTH WITH TEMPERATURES
SETTLING BACK INTO MID AND UPPER 40S ACRS THE NORTH...WHILE SOUTH
OF THE COLD FRONT...TEMPERATURES WERE STILL IN THE LOW 70S OVER
PARTS OF SE IL.
THE FRONT SHOULD SHIFT SOUTH AND EAST OF OUR AREA BY MIDNIGHT
TAKING THE RAIN THREAT WITH IT. FURTHER TO OUR NORTHWEST...A
SECONDARY COLD FRONT WAS TRACKING SE OUT OF THE NORTHERN MIDWEST
BRINGING ANOTHER BAND OF SHOWERS SOUTH WITH IT. STILL APPEARS OUR
NORTHERN AREAS STAND THE BEST CHANCE OF SEEING SOME WDLY SCT
SHOWERS BY DAWN. ADJUSTMENTS WERE MADE TO THE HOURLY TEMPERATURE
GRIDS AS WELL AS WITH THE OVERNIGHT LOWS AS A LOCATIONS...ESP ACRS
THE NORTH...WERE ALREADY AT OR BELOW THE FORECAST LOWS FOR THE
NIGHT. THE UPDATED ZONES SHOULD BE OUT AROUND 900 PM.
SMITH
&&
.AVIATION...
ISSUED 600 PM CDT FRI SEP 21 2012
CONVECTION CONTINUES TO PUSH EAST AND SOUTHEAST AS WEAK LOW PRESSURE
OVER WEST CENTRAL IL SHIFTS INTO SOUTH CENTRAL IL. IT APPEARS AS THE
LOW SHIFTS SOUTH OF THE TAF SITES...THE HIGHER THREAT FOR SCATTERED
SHOWERS WILL BE IN DEC AND CMI FOR THE FIRST HALF OF THE EVENING.
SOME OF THOSE SHOWERS MAY BRIEFLY TAKE CIGS DOWN TO MVFR BUT FOR THE
MOST PART...BASED ON THE CURRENT SATELLITE TRENDS OUT WEST AND NW...
VFR CONDITIONS ARE EXPECTED THIS FORECAST PERIOD. TOUGH WIND FORECAST
EARLY THIS EVENING AS THE SFC LOW SLIPS JUST SOUTH OF SPI AND DEC.
LOOKS AS IF WINDS WILL SHIFT INTO A NORTHERLY DIRECTION OVER THE NEXT
SEVERAL HOURS. OTHERWISE...AT THE REMAINDER OF THE TAF SITES...NORTH
TO NORTHWEST WINDS SHOULD PREVAIL OVERNIGHT WITH A TREND TOWARDS WEST
TO SOUTHWEST LATE TONIGHT AHEAD OF A SECONDARY COLD FRONT WHICH IS
SLATED TO PUSH ACROSS OUR AREA SATURDAY MORNING WITH GUSTY NW WINDS
EXPECTED IN THE AFTERNOON.
SMITH
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT FRI SEP 21 2012
SHORT TERM...TODAY THROUGH MONDAY
INITIAL CONCERN IS SLIGHT RISK OF SEVERE STORMS INTO EARLY EVENING
MAINLY EAST OF THE IL RIVER. SHORT RANGE MODELS FAIRLY SIMILAR
THROUGH MON WITH STRONG UPPER LEVEL TROF DIGGING SOUTHWARD INTO
THE GREAT LAKES AND OHIO VALLEY REGION BY SAT WITH BELOW NORMAL
TEMPS EXPECTED THIS WEEKEND. PATCHY FROST STILL A POSSIBILITY OVER
THE IL RIVER VALLEY LATER SAT NIGHT AND IN EASTERN IL LATER SUNDAY
NIGHT. MET AND MAV GUIDANCE TEMPS SIMILAR THROUGH SUNDAY NIGHT AND
STAYED FAIRLY CLOSE TO.
MID AFTERNOON SURFACE MAP SHOWS 1006 MB LOW PRESSURE DEEPENING
ALONG THE EASTERN IA/MO BORDER WITH ITS WARM FRONT LIFTING
NORTHWARD TOWARD I-74...AS ENE WINDS TURN SOUTH WITH ITS PASSAGE AND
DEWPOINTS IN THE UPPER 30S AND 40S RISE INTO THE MID TO UPPER 50S.
TEMPS RISING AS WELL INTO THE UPPER 70S AND LOWER 80S IN SW IL IN
WARM SECTOR WHERE ALSO MORE SUNSHINE. SOME INSTABILITY WITH CAPES
PEAKING FROM 1000-1500 J/KG EAST OF THE IL RIVER THIS AFTERNOON
WITH INCREASING WIND SHEAR AS WELL DURING MID/LATE AFTERNOON INTO
EARLY EVENING AS 35-40KT WSW LOW LEVEL JET WHILE ALSO GETTING
STRONGER THAN 80-100 KT JET ALOFT DIVING SE INTO IL LATE TODAY
ALONG WITH A SHORT WAVE MOVING INTO CENTRAL IL FROM IA LATE TODAY.
VGP PARMETERS ARE FAVORABLE FOR ISOLATED TORNADOES IN SE IL LATE
THIS AFTERNOON/EARLY EVENING. SO CONCUR WITH SPC/S UPGRADE TO A
SLIGHT RISK OF SEVERE STORMS FROM MID AFTERNOON INTO EARLY EVENING
MAINLY SE OF THE IL RIVER. SPC HAS 15% RISK OF LARGE HAIL AND
DAMAGING WIND GUSTS ALONG WITH 5% RISK OF TORNADOES.
LOW PRESSURE DEEPENS A BIT MORE TO 1005 MB AND DIVES SE INTO SW IL
BY SUNSET AND THEN TURN NE ACROSS THE OHIO RIVER THIS EVENING.
RUC13 AND HRRR MODELS KEEP HEALTHY CHANCES OF SHOWERS AND
THUNDERSTORMS OVER EASTERN IL THROUGH MID EVENING AND THEN
DIMINISH BY LATE EVENING AND TRENDED FORECAST IN THAT DIRECTION.
WESTERN IL SHOULD BE DRY THIS EVENING WITH CONVECTION EAST OF
THERE. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO
THE LOWER 50S SE OF I-70 IN SE IL.
UNSEASONABLY STRONG 533 DM 500 MB DOUBLE BARREL LOW OVER NW
ONTARIO TO CONTINUE DIGGING SOUTHWARD INTO THE GREAT LAKES AND
OHIO VALLEY TONIGHT/SAT WHILE SENDING A STRONG SHORT WAVE FROM
LAKE WINNIPEG SE INTO EASTERN IA/NORTHERN IL/SW WI BY SUNRISE SAT
AND INTO NORTHERN INDIANA BY 18Z/1 PM SAT. CONTINUE 20% CHANCE OF
SHOWERS LATE TONIGHT NORTH OF PEORIA AND 20-30% CHANCE NE OF I-74
SAT MORNING ALONG WITH GUSTS NORTH WINDS UP TO 30 MPH NE AREAS.
HIGHS AROUND 60F FROM I-74 NE SAT AND MID 60S IN SE IL AND SW OF
SPRINGFIELD.
1026 MB HIGH PRESSURE OVER SASKETCHEWAN TO BUILD INTO THE EASTERN
PLAINS SUNDAY AND RETURN LIGHER WINDS TO THE AREA BUT CONTINUE
COOL WEATHER. FROST IS LIKELY OVER THE IL RIVER VALLEY LATER SAT
NIGHT WITH LOWS IN THE MID 30S. APPEARS SHY OF RECORD LOWS AROUND
30F EARLY SUNDAY MORNING SEP 23 BUT NEAR FREEZING TEMPS POSSIBLE
IN NW IL NW OF KNOX AND STARK COUNTIES. PATCHY FROST IS POSSIBLE
OVER EASTERN IL LATER SUNDAY NIGHT WITH LOW IN THE MID TO UPPER
30S AS SURFACE HIGH DRIFTS OVER CENTRAL/SE IL AND EVENTUALLY INTO
THE OHIO RIVER VALLEY BY DAWN MON. HIGHS SUNDAY STAYING COOL IN THE
LOW TO MID 60S DESPITE A FAIR AMOUNT OF SUNSHINE.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
UNSETTLED WEATHER PATTERN TAKING SHAPE LATER MON NIGHT THROUGH MID
WEEK AS SEVERAL SHORT WAVES WILL EJECT FROM THE CENTRAL PLAINS
TOWARD IL AND ALSO HAVE A FRONTAL BOUNDARY MOVING SOUTHWARD AND
POSSIBLY LINGERING NEAR CENTRAL/SE IL FOR A FEW DAYS DURING
MIDWEEK. THIS WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS
AROUND FOR A FEW DAY BUT THINK GFS IS LINGERING QPF TOO LONGER
INTO LATE WEEK AND LEANED TOWARD THE FURTHER SOUTH ECWMF MODEL
WITH THE FRONT BY THU/FRI. GENERALLY STAYED CLOSE TO ALLBLEND POPS
DURING NEXT WORK WEEK AND LINGERED SLIGHT CHANCES SOUTHERN AREAS
AROUND THU. TEMPERATURES TO WARM BACK TO NORMAL BY TUE AND COOLING
OFF FROM NORTH TO SOUTH LATER NEXT WEEK AND COULD BE MORE OF A
TEMPERATURE CONTRAST THAN WHAT ALLBLEND IS SHOWING DURING 2ND HALF
OF NEXT WEEK DEPENING ON POSITION OF FRONTAL BOUNDARY.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
639 PM CDT FRI SEP 21 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
.DISCUSSION...
348 PM CDT
COOL THROUGH THE WEEKEND THEN TEMPERATURES MODERATE FIRST PART OF
NEXT WEEK. A SHORT BREAK IN THREAT OF RAIN THIS EVENING THEN
CHANCES RETURN OVERNIGHT THROUGH SAT MORNING.
MULTIPLE MINOR SHORT WAVES IN THE UPPER FLOW TURNING FROM SSE TO
SE AS THEY CROSS THE UPPER MIDWEST AND THEN SE TO ESE AS THEY
ROTATE ACROSS THE MID MS VALLEY AND THE WESTERN GREAT LAKES INTO
THE BASE OF THE UPPER TROUGH THE REST OF TODAY AND THIS EVENING.
FURTHER UPSTREAM OVER SOUTHERN MANITOBA IS A STRONGER SHORT WAVE
PROGGED TO REACH SOUTHERN WI BY 12Z SAT. AS THIS DISTURBANCE
APPROACHES LATE TONIGHT A CHANCE OF RAIN RETURNS
OVERNIGHT...ENDING MIDDAY WITH THIS SHORT WAVE TROUGH PROGGED TO
CONTINUE ON TO NORTHERN IND BY 18Z SAT. HIGHEST CHANCES WILL BE
ACROSS THE NE 1/2 OF THE FORECAST AREA...ALONG AND N OF THE
PROJECTED PATH OF THE VORT MAX.
IN THE WAKE OF THE SHORT WAVE/WAVES MOVING ACROSS THE AREA TODAY
WEAK LOW LEVEL COLD AIR ADVECTION TO TAKE PLACE. THIS...COMBINED
WITH EXPECTED SHOWERS AND EXTENSIVE CLOUDINESS...WILL KEEP
TEMPERATURES DURING SAT LIMITED TO THE UPPER 50S AND LOWER 60S.
WITH THE PASSAGE OF THE STRONGER SHORT WAVE DURING SAT MORNING
STRONGER COLD AIR ADVECTION TO TAKE PLACE WITH 850HPA
TEMPERATURES DROPPING TO AROUND 0C FOR THE AFTERNOON. DESPITE THE
COLD AIR ADVECTION SURFACE HEATING IS EXPECTED TO MITIGATE THE
COOLING AS CLOUDS CLEAR DURING THE DAY IN THE WAKE OF THE SHORT
WAVE.
A HIGH PRESSURE RIDGE IS TO BE BUILDING FROM THE NORTHERN PLAINS
ACROSS THE MO RIVER VALLEY DURING THE DAY SAT AND THE UPPER AND
MID MS VALLEY AND LOWER OH VALLEY DURING SAT NIGHT. CLEAR
SKIES...DEW POINTS IN THE MID 20S TO LOWER 30S...AND LACK OF
BOUNDARY LAYER MIXING AS SURFACE WINDS BECOME NIL ARE EXPECTED TO
LEAD TO SAT NIGHT LOWS IN THE LOWER AND MID 30S ACROSS MUCH OF
THE LOCAL FORECAST AREA. FROST A GOOD POSSIBILITY ACROSS THE W
AND SW PORTIONS OF THE FORECAST AREA...CLOSEST TO THE SURFACE
RIDGE AXIS...OVERNIGHT SAT AND EARLY SUN MORNING.
YET ANOTHER SHORT WAVE IS SHOWN BY MODELS DROPPING OVER THE UPPER
MIDWEST AND THE WESTERN GREAT LAKES DURING SUN. HOWEVER...WITH A
VERY DRY AIR MASS IN PLACE POPS ONLY IN THE SINGLE DIGITS. EVEN
CLOUDS WILL BE HARD TO COME BY WITH JUST SOME CIRRUS ASSOCIATED
WITH THE JET MAX MOVING OVERHEAD. WITH THE UPPER TROUGH
BROADENING OVER THE REGION AND THE CENTER OF THE CENTER OF THE
LARGE SCALE UPPER CYCLONE REESTABLISHING ITSELF OVER SOUTHERN
HUDSON BAY AND NW QUEBEC BY MON MORNING THE MID LATITUDE UPPER
FLOW BACKS TO OUT OF THE WNW. WITH THE UPPER LOW FURTHER NORTH
DISTURBANCES ROTATING AROUND IT WILL TRACK OVER THE NORTH WOODS
AND THE NORTHERN GREAT LAKES KEEPING CHANCES OF PRECIPITATION LOW
THROUGH MON NIGHT.
HOWEVER...A COLD FRONT IS PROGGED TO SLIP SE ACROSS THE LOCAL
AREA TUE AND TUE NIGHT BEFORE BECOMING STATIONARY FROM NE MO
ACROSS CENTRAL IL TO NORTHERN IND BY WED MORNING. INCREASING FLOW
FROM THE CENTRAL PLAINS ENE ACROSS THE MID MS VALLEY WILL RESULT
IN INCREASING WARM AIR ADVECTION AS WELL AS MID AND LOWER LEVEL
MOISTURE TRANSPORT INTO THE AREA WITH CHANCES OF SHOWERS AND
THUNDERSTORMS...MAINLY FOR THE N 1/2 TO 3/4 OF THE LOCAL FORECAST
AREA TUE THROUGH WED BEFORE A STRONG SHORT WAVE DROPPING ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES PUSHES THE SURFACE FRONT
FURTHER TO THE S AND ANOTHER LARGE SURFACE ANTICYCLONE BUILDS OVER
THE UPPER MIDWEST AND THE GREAT LAKES DURING WED AND WED NIGHT.
WED NIGHT THROUGH FRI WILL HAVE LOW POPS AS THE HIGH PRESSURE WILL
DOMINATE THE WEATHER OVER THE REGION...CONTINUING TO FEED COOL DRY
AIR ACROSS THE AREA.
TRS
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 00Z...
* VARIABLE WIND DIRECTION THROUGH EARLY EVENING.
* LIGHT RAIN ENDING BY MID-EVENING.
* SHOWERS DEVELOPING AGAIN TOWARD MORNING...WITH PATCHY MVFR
CONDITIONS POSSIBLE.
* STRONG NORTHWEST WINDS GUSTING 25-30 KTS SATURDAY.
RATZER
//DISCUSSION...UPDATED 00Z...
LOW PRESSURE WAS MOVING ACROSS CENTRAL ILLINOIS LATE THIS
AFTERNOON...AND WILL MOVE QUICKLY EAST INTO INDIANA THIS EVENING.
LIGHT RAIN CURRENTLY OVER NORTHERN IL/LAKE MICHIGAN WILL MOVE OFF
TO THE EAST BY MID-EVENING AS THE LOW AND ITS ASSOCIATED MID-LEVEL
DISTURBANCE DEPART. SURFACE WINDS HAD BECOME NORTHEAST AND
INCREASED A BIT IN RESPONSE TO THE DEEPENING OF THE LOW...BUT WERE
BEGINNING TO BECOME MORE LIGHT/VARIABLE WITHIN AN AREA OF WEAK
HIGH PRESSURE OVER FAR NORTHERN IL. WIND DIRECTION WILL CONTINUE
TO BE RATHER VARIABLE THROUGH THE MID-EVENING HOURS...BEFORE
BECOMING MORE WESTERLY AHEAD OF ANOTHER COLD FRONT MOVING RAPIDLY
SOUTHEAST ACROSS THE UPPER MIDWEST. SPEEDS SHOULD GENERALLY BE
LESS THAN 10 KTS HOWEVER UNTIL THE FRONT APPROACHES EARLY
SATURDAY. OTHER THAN SOME PATCHY FEW-SCT MVFR LAYER CLOUDS WITH
THE SHOWERS EARLY THIS EVENING...VFR CONDITIONS ARE EXPECTED WITH
BKN-OVC MID DECK AROUND 8 KFT. SHOULD THIS DECK ERODE THERE COULD
BE THE POTENTIAL FOR SOME SHALLOW FOG TO DEVELOP GIVEN LIGHT WINDS
AND MOIST GROUND...THOUGH THE MID DECK LOOKS TO PREVAIL THROUGH
THE EVENING.
STRONG COLD FRONT MOVES THROUGH THE AREA EARLY SATURDAY
MORNING...SHIFTING WINDS TO THE NORTHWEST 310-330 DEGREES WITH
INCREASINGLY GUSTY CONDITIONS. FORECAST SOUNDINGS INDICATE GUST
POTENTIAL IN THE 25-30 KT RANGE AT TIMES WITH SUSTAINED SPEEDS
15-20 KTS. STRONG MID-LEVEL DISTURBANCE SHOULD SUPPORT SHOWERS
DURING THE MORNING...WHICH MAY PRODUCE MVFR CIG/VIS CONDITIONS.
STRATOCU CIGS SHOULD RISE TO VFR BY EARLY AFTERNOON HOWEVER AS
MUCH DRIER AIR SPREADS IN.
RATZER
//ORD AND MDW CONFIDENCE...UPDATED 00Z...
* MEDIUM-HIGH CONFIDENCE IN WIND TRENDS TONIGHT.
* HIGH CONFIDENCE IN TIMING OF PRECIP/CIGS THROUGH PERIOD.
* HIGH CONFIDENCE IN WIND TRENDS SATURDAY.
RATZER
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR. DIMINISHING WEST-NORTHWEST WINDS.
MONDAY...VFR.
TUESDAY...VFR. CHC SHRA.
WEDNESDAY...VFR.
THURSDAY...VFR.
RATZER
&&
.MARINE...
230 PM CDT
LOW PRESSURE OVER THE UPPER GREAT LAKES WILL TRACK NORTHEAST
TOWARD HUDSON BAY OVERNIGHT TONIGHT AND THEN RAPIDLY DEEPEN
TOMORROW AS STRONG HIGH PRESSURE BUILDS ACROSS THE NORTHERN
PLAINS. A SERIES OF MID LEVEL IMPULSES WILL BRING REINFORCING
SHOTS OF COLD AIR OVER THE WESTERN GREAT LAKES TOMORROW. THE
RESULTANT STRONG COLD ADVECTION WILL LEAD TO RAPIDLY
STRENGTHENING NORTHERLY WINDS TOMORROW...LIKELY REACHING GALE
FORCE DURING THE AFTERNOON HOURS. THE PRESSURE GRADIENT AND COLD
ADVECTION WILL BE STRONGEST OVER THE FAR NORTHERN PORTIONS OF THE
LAKE...SO HAVE HOISTED A GALE WARNING FOR THE NORTHERN ONE-THIRD
OF THE LAKE. THE WINDOW OF OPPORTUNITY FOR THE STRONGEST WINDS
WILL BE DURING THE AFTERNOON AND EVENING HOURS WHEN HIGH PRESSURE
SPREADING INTO THE WESTERN GREAT LAKES SHOULD HELP ALLOW WINDS TO
SUBSIDE BELOW GALE FORCE. FOR THE SOUTHERN PORTIONS OF THE
LAKE...WINDS AND WAVES SHOULD QUICKLY RISE TO SMALL CRAFT
ADVISORY LEVELS TOMORROW AS WELL...WITH THE INDIANA WATERS
REACHING SMALL CRAFT ADVISORY LEVELS SOONER THAN THE ILLINOIS
WATERS...AND LINGERING LONGER...INTO MONDAY MORNING DUE TO THE
GENERALLY NORTHERLY FETCH SETTING UP OVER THE LAKE. BY MONDAY
AFTERNOON...ANOTHER DEEPENING LOW TRACKING JUST NORTH OF THE
GREAT LAKES MAY POSSIBLY BRING ANOTHER BRIEF PERIOD OF
SOUTHWESTERLY GALES TO THE FAR NORTHERN PORTION OF THE LAKE...
BUT WILL NOT ISSUE ANY HEADLINES AT THIS TIME SINCE THE STRENGTH
OF THE WINDS WILL BE HIGHLY DEPENDENT ON THE EXACT TRACK OF THE
LOW.
THE OTHER CONCERN FOR LAKE MICHIGAN WILL BE WATERSPOUT POTENTIAL.
LAKE SFC WATER TEMPERATURES REMAIN UNUSUALLY HIGH...WITH A
TEMPERATURE OF 17C AT THE NORTH BUOY AND 20C AT THE SOUTH BUOY
THIS AFTERNOON. WHEN THE MUCH COOLER AIR PLUNGES OVER LAKE
MICHIGAN...LAKE SFC TO 850MB DELTA-T VALUES WILL REACH AS HIGH AS
22-23C...INDICATIVE OF A VERY UNSTABLE ENVIRONMENT OVER LAKE
MICHIGAN. WHILE CONVERGENCE BOUNDARIES ARE NOT LIKELY OVER THE
LAKE...WATERSPOUT POTENTIAL WILL REMAIN HIGH DUE TO LAKE EFFECT
RAIN SHOWERS AND DEEP LAYER CONVECTIVE CLOUD DEVELOPMENT.
CONDITIONS WILL BE CONDUCIVE TO WATERSPOUTS FROM THIS EVENING
THROUGH MONDAY EVENING...ESPECIALLY FOR THE NORTHERN AND EASTERN
PORTIONS OF THE LAKE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
604 PM CDT FRI SEP 21 2012
.DISCUSSION...
ISSUED 300 PM CDT FRI SEP 21 2012
SHORT TERM...TODAY THROUGH MONDAY
INITIAL CONCERN IS SLIGHT RISK OF SEVERE STORMS INTO EARLY EVENING
MAINLY EAST OF THE IL RIVER. SHORT RANGE MODELS FAIRLY SIMILAR
THROUGH MON WITH STRONG UPPER LEVEL TROF DIGGING SOUTHWARD INTO
THE GREAT LAKES AND OHIO VALLEY REGION BY SAT WITH BELOW NORMAL
TEMPS EXPECTED THIS WEEKEND. PATCHY FROST STILL A POSSIBILITY OVER
THE IL RIVER VALLEY LATER SAT NIGHT AND IN EASTERN IL LATER SUNDAY
NIGHT. MET AND MAV GUIDANCE TEMPS SIMILAR THROUGH SUNDAY NIGHT AND
STAYED FAIRLY CLOSE TO.
MID AFTERNOON SURFACE MAP SHOWS 1006 MB LOW PRESSURE DEEPENING
ALONG THE EASTERN IA/MO BORDER WITH ITS WARM FRONT LIFTING
NORTHWARD TOWARD I-74...AS ENE WINDS TURN SOUTH WITH ITS PASSAGE AND
DEWPOINTS IN THE UPPER 30S AND 40S RISE INTO THE MID TO UPPER 50S.
TEMPS RISING AS WELL INTO THE UPPER 70S AND LOWER 80S IN SW IL IN
WARM SECTOR WHERE ALSO MORE SUNSHINE. SOME INSTABILITY WITH CAPES
PEAKING FROM 1000-1500 J/KG EAST OF THE IL RIVER THIS AFTERNOON
WITH INCREASING WIND SHEAR AS WELL DURING MID/LATE AFTERNOON INTO
EARLY EVENING AS 35-40KT WSW LOW LEVEL JET WHILE ALSO GETTING
STRONGER THAN 80-100 KT JET ALOFT DIVING SE INTO IL LATE TODAY
ALONG WITH A SHORT WAVE MOVING INTO CENTRAL IL FROM IA LATE TODAY.
VGP PARMETERS ARE FAVORABLE FOR ISOLATED TORNADOES IN SE IL LATE
THIS AFTERNOON/EARLY EVENING. SO CONCUR WITH SPC/S UPGRADE TO A
SLIGHT RISK OF SEVERE STORMS FROM MID AFTERNOON INTO EARLY EVENING
MAINLY SE OF THE IL RIVER. SPC HAS 15% RISK OF LARGE HAIL AND
DAMAGING WIND GUSTS ALONG WITH 5% RISK OF TORNADOES.
LOW PRESSURE DEEPENS A BIT MORE TO 1005 MB AND DIVES SE INTO SW IL
BY SUNSET AND THEN TURN NE ACROSS THE OHIO RIVER THIS EVENING.
RUC13 AND HRRR MODELS KEEP HEALTHY CHANCES OF SHOWERS AND
THUNDERSTORMS OVER EASTERN IL THROUGH MID EVENING AND THEN
DIMINISH BY LATE EVENING AND TRENDED FORECAST IN THAT DIRECTION.
WESTERN IL SHOULD BE DRY THIS EVENING WITH CONVECTION EAST OF
THERE. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO
THE LOWER 50S SE OF I-70 IN SE IL.
UNSEASONABLY STRONG 533 DM 500 MB DOUBLE BARREL LOW OVER NW
ONTARIO TO CONTINUE DIGGING SOUTHWARD INTO THE GREAT LAKES AND
OHIO VALLEY TONIGHT/SAT WHILE SENDING A STRONG SHORT WAVE FROM
LAKE WINNIPEG SE INTO EASTERN IA/NORTHERN IL/SW WI BY SUNRISE SAT
AND INTO NORTHERN INDIANA BY 18Z/1 PM SAT. CONTINUE 20% CHANCE OF
SHOWERS LATE TONIGHT NORTH OF PEORIA AND 20-30% CHANCE NE OF I-74
SAT MORNING ALONG WITH GUSTS NORTH WINDS UP TO 30 MPH NE AREAS.
HIGHS AROUND 60F FROM I-74 NE SAT AND MID 60S IN SE IL AND SW OF
SPRINGFIELD.
1026 MB HIGH PRESSURE OVER SASKETCHEWAN TO BUILD INTO THE EASTERN
PLAINS SUNDAY AND RETURN LIGHER WINDS TO THE AREA BUT CONTINUE
COOL WEATHER. FROST IS LIKELY OVER THE IL RIVER VALLEY LATER SAT
NIGHT WITH LOWS IN THE MID 30S. APPEARS SHY OF RECORD LOWS AROUND
30F EARLY SUNDAY MORNING SEP 23 BUT NEAR FREEZING TEMPS POSSIBLE
IN NW IL NW OF KNOX AND STARK COUNTIES. PATCHY FROST IS POSSIBLE
OVER EASTERN IL LATER SUNDAY NIGHT WITH LOW IN THE MID TO UPPER
30S AS SURFACE HIGH DRIFTS OVER CENTRAL/SE IL AND EVENTUALLY INTO
THE OHIO RIVER VALLEY BY DAWN MON. HIGHS SUNDAY STAYING COOL IN THE
LOW TO MID 60S DESPITE A FAIR AMOUNT OF SUNSHINE.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
UNSETTLED WEATHER PATTERN TAKING SHAPE LATER MON NIGHT THROUGH MID
WEEK AS SEVERAL SHORT WAVES WILL EJECT FROM THE CENTRAL PLAINS
TOWARD IL AND ALSO HAVE A FRONTAL BOUNDARY MOVING SOUTHWARD AND
POSSIBLY LINGERING NEAR CENTRAL/SE IL FOR A FEW DAYS DURING
MIDWEEK. THIS WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS
AROUND FOR A FEW DAY BUT THINK GFS IS LINGERING QPF TOO LONGER
INTO LATE WEEK AND LEANED TOWARD THE FURTHER SOUTH ECWMF MODEL
WITH THE FRONT BY THU/FRI. GENERALLY STAYED CLOSE TO ALLBLEND POPS
DURING NEXT WORK WEEK AND LINGERED SLIGHT CHANCES SOUTHERN AREAS
AROUND THU. TEMPERATURES TO WARM BACK TO NORMAL BY TUE AND COOLING
OFF FROM NORTH TO SOUTH LATER NEXT WEEK AND COULD BE MORE OF A
TEMPERATURE CONTRAST THAN WHAT ALLBLEND IS SHOWING DURING 2ND HALF
OF NEXT WEEK DEPENING ON POSITION OF FRONTAL BOUNDARY.
KH
&&
.AVIATION...
ISSUED 600 PM CDT FRI SEP 21 2012
CONVECTION CONTINUES TO PUSH EAST AND SOUTHEAST AS WEAK LOW PRESSURE
OVER WEST CENTRAL IL SHIFTS INTO SOUTH CENTRAL IL. IT APPEARS AS THE
LOW SHIFTS SOUTH OF THE TAF SITES...THE HIGHER THREAT FOR SCATTERED
SHOWERS WILL BE IN DEC AND CMI FOR THE FIRST HALF OF THE EVENING.
SOME OF THOSE SHOWERS MAY BRIEFLY TAKE CIGS DOWN TO MVFR BUT FOR THE
MOST PART...BASED ON THE CURRENT SATELLITE TRENDS OUT WEST AND NW...
VFR CONDITIONS ARE EXPECTED THIS FORECAST PERIOD. TOUGH WIND FORECAST
EARLY THIS EVENING AS THE SFC LOW SLIPS JUST SOUTH OF SPI AND DEC.
LOOKS AS IF WINDS WILL SHIFT INTO A NORTHERLY DIRECTION OVER THE NEXT
SEVERAL HOURS. OTHERWISE...AT THE REMAINDER OF THE TAF SITES...NORTH
TO NORTHWEST WINDS SHOULD PREVAIL OVERNIGHT WITH A TREND TOWARDS WEST
TO SOUTHWEST LATE TONIGHT AHEAD OF A SECONDARY COLD FRONT WHICH IS
SLATED TO PUSH ACROSS OUR AREA SATURDAY MORNING WITH GUSTY NW WINDS
EXPECTED IN THE AFTERNOON.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1048 PM EDT FRI SEP 21 2012
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 236 PM EDT FRI SEP 21 2012
A SURFACE WAVE AND COLD FRONT WILL MOVE OUT OF CENTRAL INDIANA
OVERNIGHT WITH WIDESPREAD RAINFALL ENDING. IT WILL BE MUCH COOLER
ON SATURDAY WITH A CHANCE OF SHOWERS ACROSS THE NORTHERN HALF OF
CENTRAL INDIANA AS AN UPPER WAVE PASSES ACROSS NORTHERN INDIANA.
THEN...EXPECT DRY WEATHER WITH MUCH BELOW NORMAL TEMPERATURES
THROUGH MONDAY AS HIGH PRESSURE BUILDS IN FROM THE CANADIAN
PRAIRIES. AFTERNOON TEMPERATURES ARE ONLY EXPECTED TO REACH THE
60S. NORTHERN SECTIONS WILL ONLY SEE THE UPPER 50S THROUGH SUNDAY.
MEANWHILE AREAS AWAY FROM THE CITY SHOULD BOTTOM OUT IN THE 30S
SATURDAY NIGHT AND SUNDAY NIGHT. PATCHY FROST WILL BE POSSIBLE
ESPECIALLY SUNDAY NIGHT. THUNDERSTORM CHANCES WILL RETURN BY
MONDAY NIGHT AS A FRONT DROPS DOWN FROM THE NORTH. TEMPERATURES
WILL WARM BACK INTO THE 70S BY TUESDAY AS HIGH PRESSURE SHIFTS TO
THE EAST COAST ALLOWING RETURN FLOW FROM THE GULF OF MEXICO.
&&
.NEAR TERM /OVERNIGHT/...
ISSUED AT 1047 PM EDT FRI SEP 21 2012
LOW PRESSURE CURRENTLY LOCATED OVER WESTERN INDIANA AS OF 02Z.
LINEAR CONVECTION NOW LARGELY CONFINED TO POINTS ALONG AND SOUTH
OF A MUNCIE TO INDY METRO TO TERRE HAUTE LINE. TEMPS REMAINED IN
THE 60S OVER SOUTHERN COUNTIES WHERE RAIN HAD NOT YET FALLEN...
WITH CHILLY 50S ELSEWHERE.
THE LOW WILL TRACK EAST ACROSS THE FORECAST AREA OVER THE NEXT
FEW HOURS WITH THE ASSOCIATED FRONTAL BOUNDARY STEADILY PUSHING
SOUTH AND EAST OUT OF THE FORECAST AREA. HAVE LEANED HEAVILY ON
THE HRRR FOR THE OVERNIGHT WITH THE BULK OF THE RAINFALL LIKELY TO
BE OUT OF THE FORECAST AREA BY 06-07Z WITH JUST LIGHT SCATTERED
PRECIP IN ITS WAKE. ADJUSTED POPS TO ACCOUNT FOR THIS THINKING.
SATELLITE TRENDS SUGGEST CLOUDS WILL SCATTER PRIOR TO DAYBREAK AND
WITH LIGHTENING WINDS AND WET GROUND FROM THE EVENING RAIN...MAY
SEE SOME PATCHY FOG DEVELOP LATE AS WELL.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 150 PM EDT FRI SEP 21 2012
THE MAIN FOCUS OVER THE SHORT TERM WILL BE ON POPS ON SATURDAY ALONG
WITH TEMPERATURES...AND FROST POTENTIAL MAINLY SUNDAY OVERNIGHT.
MODELS ALL IN GOOD AGREEMENT ON PERSISTENT HUDSON BAY VORTEX WITH
UPPER WAVES DROPPING AROUND THE BASE OF THE ASSOCIATED TROUGH.
MODELS HAVE ONE SUCH WAVE MOVING TO NEAR SOUTH BEND BY 18Z SATURDAY
WITH A COMPACT AREA OF DEEPER MOISTURE ASSOCIATED WITH IT. THIS
SUGGESTS LIGHT QPF ACROSS OUR NORTH PER THE MODELS LOOKS GOOD. WILL
USE ALLBLEND. BY SATURDAY NIGHT...THERE SHOULD BE LITTLE CLOUD COVER
AS CANADIAN HIGH PRESSURE BUILDS IN. SUNDAY NIGHT WILL FIND THE
SURFACE HIGH NEAR LOUISVILLE WITH LIGHT TO CALM WINDS AND CLEAR
SKIES. THIS COULD ALLOW PATCHY FROST EXCEPT NEAR THE CITY.
MOS TEMPERATURES PRETTY CLOSE THROUGH THE PERIOD AND APPEARS
REASONABLE.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 228 PM EDT FRI SEP 21 2012
SEVERAL WAVES WILL MOVE THROUGH THE MAIN FLOW...AN UPPER LEVEL
TROUGH...THROUGH MUCH OF THE LONG TERM. WHILE MODELS SHOW SOME
SLIGHT DIFFERENCES IN THE DETAILS...ALL SHOW A FRONT WILL MOVE INTO
CENTRAL INDIANA AND STALL OUT OVER THE AREA. THIS WILL KEEP CHANCES
FOR SHOWERS AND THUNDERSTORMS /DUE TO THE PRESENCE OF AT LEAST
ELEVATED INSTABILITY/ IN THE FORECAST FROM MONDAY NIGHT THROUGH
WEDNESDAY NIGHT. FROM THURSDAY ON THE MODELS SHOW MORE VARIABILITY.
0Z ECM SHOWS THE FRONT SLOWLY MOVING THROUGH THE AREA TUE AND WEDS
AND WASHING OUT SOUTH OF THE AREA ON THU WITH DRY WEATHER HERE AND
HIGH PRESSURE BUILDING IN. GFS ENSEMBLE AVERAGE SHOWS THE FRONT
STILL ACROSS THE AREA ON THURSDAY AND NOT SHOVED SOUTH UNTIL THU
NIGHT. 12Z GFS IS A LITTLE SLOWER THAN 0Z ECMWF AND ALSO BRINGS
ANOTHER WAVE UP FROM THE SOUTHWEST LATE THURSDAY NIGHT/FRIDAY
MORNING. WITH WIDE SPREAD IN THE ENSEMBLES FROM THURSDAY ON WILL
STICK WITH ALLBLEND AND KEEP SLIGHT CHANCES IN THE SOUTH DURING THAT
TIME.
AS FAR AS TEMPERATURES ARE CONCERNED WENT WITH ALLBLEND FOR HIGHS
GENERALLY IN THE UPPER 60S TO MIDDLE 70S UNTIL FRIDAY...BUT WOULD
NOT BE SURPRISED TO SEE A TIGHTER GRADIENT ACROSS THE AREA DEPENDING
ON WHERE THE FRONT SETS UP. ALLBLEND LOWS IN THE 50S LOOK GOOD WITH
SOME CLOUD COVER GIVEN THE FRONT.
&&
.AVIATION /DISCUSSION FOR THE 22/03Z TAF UPDATE/...
ISSUED AT 1026 PM EDT FRI SEP 21 2012
UPDATED TO REFLECT OBSERVATIONAL TRENDS. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 709 PM EDT FRI SEP 21 2012
MAINLY VFR THROUGH THE PERIOD...EXCEPT FOR POSSIBLE RESTRICTIONS IN
SHOWERS OR THUNDERSTORMS EARLY.
FAIRLY POTENT LOW PRESSURE SYSTEM WILL PUSH ACROSS THE AREA THIS
EVENING. SOME THUNDERSTORMS WILL THREATEN THE SITES...BUT WILL ONLY
USE VCTS AS ONLY PERSISTENT STORM WILL CLEAR THE SITE BY
00Z...ALTHOUGH ADDITIONAL STORMS ARE UPSTREAM.
WINDS WILL COME AROUND TO WEST OR NORTHWEST LATER IN THE
PERIOD...WITH GUSTS TOMORROW APPROACHING 25-30KT.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...MK/RYAN
NEAR TERM...RYAN
SHORT TERM...MK
LONG TERM....CP
AVIATION...NIELD
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1142 PM CDT WED SEP 19 2012
.AVIATION...
COLD FRONT HAS NOW MOVED THROUGH ALL OF THE TERMINALS...LEAVING US
WITH NORTHWEST WINDS AT OR BELOW 10KTS. THIS...ALONG WITH VFR
CONDITIONS WILL CONTINUE THROUGH 21ST AT 06Z. SOME MID AND HIGH
CLOUDS...BUT WITH BASES ABOVE 8KFT. THURSDAY MORNING NORTHWEST
WINDS SHOULD INCREASE TO 10-15KTS WITH SOME SITES GUSTING TO
AROUND 20KTS DUE TO PRESSURE GRADIENT ACROSS AREA. AROUND
00Z/SUNSET... WINDS TO DIMINISH AGAIN TO LESS THAN 10KTS. PLENTY
OF MID AND HIGH CLOUDS THROUGH THE PERIOD...STILL WITH BASES ABOVE
10KFT. LE
&&
.PREV DISCUSSION... /ISSUED 306 PM CDT WED SEP 19 2012/
SYNOPSIS...
12Z UA ANALYSIS HAD A STRONG UPPER LOW EAST OF LAKE WINNIPEG. THE
850MB COLD FRONT RAN FROM THE ARROW HEAD OF MINNESOTA TO EASTERN
WYOMING. THE 850MB WARM FRONT RAN SOUTH ROUGHLY ALONG THE
MISSISSIPPI RIVER. STRONG CAA WAS OCCURRING BEHIND THE UPPER FRONT
WITH 850MB TEMPERATURES QUICKLY DROPPING INTO THE SINGLE DIGITS AT
THE INTERNATIONAL BORDER. SATELLITE TRENDS THROUGH MID AFTERNOON
SHOW RAPID DEVELOPMENT OF CLOUDS ALONG THE SFC COLD FRONT FROM
SOUTHEAST MINNESOTA INTO NORTHWEST IOWA. RADARS WERE SHOWING VIRGA
DEVELOPING FROM NORTHEAST IOWA INTO WESTERN WISCONSIN.
18Z SFC ANALYSIS HAD THE COLD FRONT RUNNING FROM THE KDLH AREA TO
SOUTHEAST COLORADO. A NARROW TONGUE OF LOW AND MID 50 DEW POINTS RAN
FROM THE SOUTHERN PLAINS INTO WESTERN IOWA. DEW POINTS IN THE 40S
WERE COMMON ACROSS MUCH OF THE MIDWEST AND WESTERN GREAT LAKES. DEW
POINTS IN THE 30S WERE ACROSS THE NORTHERN PLAINS AND GREAT LAKES.
SHORT TERM...TONIGHT AND THURSDAY...
BASED ON RADAR TRENDS...VIRGA IS BECOMING MORE PRONOUNCED FROM THE
CU FIELD THAT IS DEVELOPING ALONG THE COLD FRONT AND PRE-FRONTAL
TROF. RAP TRENDS CONTINUE TO SHOW MID LEVEL FORCING WILL INCREASE
THROUGH THE REMAINDER OF THE AFTERNOON WITH IT MAXIMIZING RIGHT
AROUND 00Z. FCST SOUNDINGS INDICATE CLOUD BASES IN THE 7-10 KFT AGL
RANGE SO THE VIRGA SHOULD BE QUITE OBVIOUS LATE THIS AFTERNOON IN
THE NORTHWEST PART OF THE CWFA WITH IT POTENTIALLY COMING FROM RADAR
RETURNS OF 30 DBZ OR HIGHER. EVENTUALLY...PRECIP WILL REACH THE
GROUND SO THE SCHC/CHC FOR LATE THIS AFTERNOON STILL LOOKS OKAY.
THE FRONT WILL SWEEP ACROSS THE CWFA DURING THE EVENING HOURS. AS
THE FORCING REACHES A MAXIMUM EARLY THIS EVENING THE POTENTIAL FOR A
COUPLE OF TSRA RIGHT ALONG THE FRONT IS POSSIBLE. HOWEVER...THE
NUMBER OF TSRA SHOULD BE NO MORE THAN A HANDFUL. THERE SHOULD STILL
BE CONSIDERABLE VIRGA INTO THE EARLY EVENING WITH THE MEASURABLE
RAIN LIKELY CONFINED TO A NARROW BAND ALONG THE FRONT.
BY MID EVENING THE RAIN SHOULD BE EAST OF THE MISSISSIPPI AND EXIT
THE AREA BY MIDNIGHT. STRONG SUBSIDENCE BEHIND THE SHORTWAVE SHOULD
RESULT IN SKIES CLEARING FAIRLY QUICKLY. AS THE HIGH BUILDS IN WINDS
SHOULD BECOME LIGHT WHICH WILL ALLOW TEMPERATURES TO DROP AS THE
SKIES CLEAR. THE WAPSI VALLEY ALONG WITH FAVORED COLD AREAS IN THE
NORTHERN CWFA SHOULD SEE THE COOLEST TEMPERATURES BY SUNRISE
THURSDAY.
ON THURSDAY QUIET AND DRY CONDITIONS WITH COOLER TEMPERATURES WILL
BE SEEN AS HIGH PRESSURE QUICKLY MOVES ACROSS THE AREA. ..08..
LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...
THE EXTENDED FORECAST REMAINS VERY ACTIVE WITH MANY PASSING STRONG
SHORT WAVES ROUNDING THE BASE OF A STRONG UPPER AIR TROF IN THE
GREAT LAKES. THIS RESULTS IN SEVERAL DAYS OF FORECAST RAIN
CHANCES...WHICH ARE ALL LOW IN CONFIDENCE DUE TO THE CHANGEABLE
FORCING FORECAST FROM RUN TO RUN...AND MODEL TO MODEL. MUCH HIGHER
CONFIDENCE IS THAT WE WILL SEE A VERY COOL PERIOD OF DAYS...FOLLOWED
BY MODERATE WARMING. BY THURSDAY NIGHT THE PATTERN WILL ALREADY BE
ESTABLISHED...WITH THE 1ST OF SEVERAL WAVES ALREADY APPROACHING.
THIS SHOULD GENERATE WARM ADVECTION THEN STRONGLY FORCED COLD
FRONTAL SHOWERS FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING.
RAINFALL AMOUNTS SHOULD BE LIGHT...BUT COULD BE UP TO 0.25 IN
SPOTS...ESPECIALLY NORTHEAST. FRIDAY LOOKS TO BE BLUSTERY UNDER
THE CLOUD COVER...THEN AFTER SEVERAL HOURS OF EASING EVENING
WINDS...AND CLEAR SKIES...WE WILL SEE A VERY STRONG UPPER WAVE DROP
SOUTH. THIS FRONT WILL SWEEP THROUGH EARLY SATURDAY...RESULTING IN
GUSTY NORTH WINDS...AND VERY STRONG COLD ADVECTION. SATURDAYS
TEMPERATURES FORECAST WITH HIGHS IN THE MID 50S NORTH TO LOWER 60S
SOUTH SEEMS OPTIMISTIC DESPITE IT BEING LOWER THAN MOST GUIDANCE.
SHOULD RAIN LINGER INTO THE DAY FOR MORE THAN A FEW HOURS...WE COULD
SEE HIGHS IN THE 40S...WITH PLENTY OF WIND. SHOULD SUNSHINE BECOME
WIDESPREAD SATURDAY AFTERNOON...RESULTING IN DEEPER MIXING...A WIND
ADVISORY IS NOT OUT OF THE QUESTION.
SATURDAY NIGHT...AND SUNDAY NIGHT...A FROST OR FREEZE IS POSSIBLE.
THIS PAST MORNING...WITH ONLY 1/2 OF A NIGHT SEEING CLEAR SKIES...WE
HIT THE MID 30S WITH 850MB TEMPERATURES OF 3 DEGREE. BOTH UPCOMING
NIGHTS THIS WEEKEND SHOULD SEE 850MB TEMPS OF +1 TO -2 DEGREES.
WHILE WINDS MAY NOT BE AS LIGHT...THIS SHOULD STILL RESULT IN COOLER
NIGHTS THAN LAST NIGHT. FOR NOW...UNTIL WE ARE CERTAIN...WILL KEEP
LOWS OF MID 30S FORECAST. SUNDAY ITSELF SHOULD BE A PLEASANT BUT
COOL DAY IN THE UPPER 50S TO LOWER 60S...AS WIND SHOULD BE LESS OF
AN ISSUE.
MONDAY INTO TUESDAY...MODERATING TEMPERATURES AND A DEVELOPING
SOUTHERLY FLOW SHOULD ALLOW FOR TEMPERATURES TO RETURN TO THE UPPER
60S MONDAY...AND MID 70S TUESDAY. TUESDAY INTO WEDNESDAY...MOISTURE
ADVECTION OVER A DEVELOPING WARM FRONT NEARBY SHOULD ALLOW FOR RAIN
POSSIBILITIES...AND POSSIBLE CONVECTION.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PADUCAH KY
755 PM CDT FRI SEP 21 2012
.UPDATE...
ISSUED AT 754 PM CDT FRI SEP 21 2012
MESOSCALE UPDATE /754 PM CDT/...BASED ON THE KVWX WSR-88D VAD WIND
PROFILE...50 KNOT WINDS REACHED NEAR A 9-10KFT MSL LEVEL AROUND
0010 UTC...ABOUT TWENTY MINUTES AFTER THE BASE OF A PROGRESSIVE
SHORTWAVE REACHED THAT LEVEL. THIS ENHANCEMENT OF FASTER WINDS
ALOFT /IMPLIED SHARPENING OF LAPSE RATES/ MAY HAVE SUPPORTED THE
BRIEF INTENSIFICATION OF STORMS OVER NORTHERN JEFFERSON COUNTY
ILLINOIS THIS EVENING...AS SURFACE MOISTURE CONVERGENCE AND
INSTABILITY /NOTED IN THE LAPS SURFACE FIELDS WAS MAXIMIZED.
SURFACE LAPS DATA AT 23Z-00Z INDICATED A DECREASING SURFACE-BASED
CAPE GRADIENT AS THE STORMS MOVE TOWARD THE WABASH RIVER INTO
SOUTHWEST INDIANA...ALTHOUGH SURFACE BASED THETA-E CONVERGENCE
REMAINS STRONG IN THIS AREA. LOW LEVEL WIND FIELDS AT OR ABOVE
2KFT AGL HAS STRENGTHENED SLIGHTLY /0-5 KNOTS/ WITH SLIGHT VEERING
WITH HEIGHT THROUGH 10KFT AGL...SUGGESTING SOME DECOUPLING AT THE
SURFACE AND POSSIBLY THE DEVELOPMENT OF A WEAK LOW LEVEL JET.
THE 00Z SATURDAY GOES SOUNDER PRECIPITABLE WATER AND LIFTED INDEX
VALUES HAVE SHIFTED THE HIGHEST LAYER MOISTURE AND MARGINAL
INSTABILITY TOWARD THE PENNYRILE REGION OF WEST KENTUCKY.
WITH ALL OF THIS IN MIND...IT WILL BE DIFFICULT TO KEEP IN PHASE
AND MAINTAIN DEEP MOISTURE AND INSTABILITY FOR SUSTAINED AND
ROBUST UPDRAFTS AS THE CONVECTION MOVES ACROSS THE WABASH RIVER
OVER SOUTHWEST INDIANA.
HOWEVER...IR SATELLITE IMAGERY STILL SHOWS PERSISTENT WATER CLOUD
EAST OF THE CURRENT CONVECTIVE ACTIVITY...POSSIBLY ADDED BY LARGE
SCALE SYNOPTIC LIFT. AS THE ZONE OF STRONGER WINDS INTERACTS WITH
THIS LAYER...WE MAY SEE ELEVATED SHOWERS /AND POSSIBLY A
THUNDERSTORM OR TWO/ EXPAND SLOWLY SOUTH AND EAST BETWEEN 8PM AND
10 PM INTO THE PENNYRILE REGION OF WEST KENTUCKY. ANY SEVERE
POTENTIAL WILL BE MINIMAL TO NON-EXISTENT.
THE NEWLY ARRIVED 01Z SATURDAY SPC DAY ONE OUTLOOK HAS SHIFTED ANY
REMAINING SLIGHT RISK OF SEVERE STORMS OUT OF THE WFO PAH FORECAST
AREA.
ANY CONVECTION AT ALL SHOULD BE OUT OF THE WFO PAH CWA NO LATER
THAN 06Z...1 AM CDT SATURDAY.
UPDATE ISSUED AT 556 PM CDT FRI SEP 21 2012
FORECAST UPDATE...18Z NAM 12KM AND 12Z ECMWF SEEM TO HAVE A GOOD HANDLE ON
CURRENT TRENDS. HAVE FOCUSED POPS THIS EVENING OVER THE NORTH 1/2
OF THE AREA WHERE SLIGHTLY DEEPER MOISTURE EXISTS. TEMPERATURES
THROUGH EARLY EVENING WERE UPDATED...AS EXISTING VALUES WERE
COOLING TOO FAST TOO QUICKLY GIVEN THE WINDS AHEAD OF AND WITH THE
FRONT AND CURRENT CONDITIONS. THE RUC AND NAM DNG TEMPS SUPPORT
THIS TREND. ONLY MINOR ADJUSTMENTS TO CLOUDS.
MESOSCALE UPDATE /622 PM CDT/...VISIBLE AND INFRARED SATELLITE TRENDS
SHOWED THE EVOLUTION OF ENHANCED CLOUD TOPS AT 2045Z AROUND THE
ST. LOUIS METRO AREA...WITH THE TRANSITION OF WATER TO ICE CLOUD
SHOWING UP BETWEEN 2300-2330Z TIME FRAME.,,SUGGESTING SHARPER
LAPSE RATES ALOFT TYING IN WITH SURFACE BASED INSTABILITY AND
MOISTURE JUST OUTSIDE THE WFO PAH COUNTIES IN SOUTHERN IL. GOES
SOUNDER PRECIPITABLE WATER VALUES DURING THE PAST HOUR SHOW A GOOD
PLUME OF 1.2 TO 1.5 INCHES OF WATER OVER SOUTHERN
ILLINOIS...SPREADING SOUTH AND IN EAST INTO SOUTHEAST
MISSOURI...WEST KENTUCKY AND SOUTHWEST INDIANA. THE LIMITING
FACTOR...BASED ON SURFACE INSTABILITY...IS SUGGESTED BY THE GOES
SOUNDER LIFTED INDEX AROUND 22Z. THE ZERO TO MINUS FOUR VALUES
ONLY GO DOWN AS FAR AS ROUTE 13 IN SOUTHERN ILLINOIS. THIS IS
CLOSE TO THE 20Z SPC SLIGHT RISK AREA DEPICTED EARLIER THIS
AFTERNOON.
AS THE BOUNDARY LAYER SLOWLY COOLS IN THE WARM SECTOR...ANTICIPATE
SOME GRADUAL REDUCTION IN SURFACE MIXING OF AIR PARCELS...WITH THE
EXCEPTION OF THE COLD FRONTAL BOUNDARY. THIS MAY LEAD TO MORE
UPSHEAR AND ELEVATED CONVECTION ALONG THE FRONT AS IT CONTINUES TO
MOVE EASTWARD INTO SOUTHEAST IL...WEST KENTUCKY AND SOUTHWEST
INDIANA WITH THE MOIST AND SLIGHTLY UNSTABLE AIR MASS. THIS MAY
LIMIT WIND AND SOME HAIL POTENTIAL LATE THIS EVENING IN THESE AREAS.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 157 PM CDT FRI SEP 21 2012
SURFACE LOW IN NE MO...WARM FRONT HAVING ADVANCED ACROSS PAH FA IS
TO OUR NORTH...PM CONVECTION STARTING TO FIRE IN ISOLATED FASHION
NEAR LOW CENTER/ALONG WARM FRONTAL BOUNDARY CENTRAL IL. THIS AREA
BEING CLOSELY MONITORED BY SPC FOR WW...HAIL WOULD BE MAIN THREAT
GIVEN ELEVATED NATURE AND COOLER TEMPS ALOFT.
MODELS THRUST COLD FRONT ACROSS PAH FA THIS EVENING. CONVECTIVE
CHANCES ATTENDANT...BEST NORTHEST...WILL EXPIRE AFT 06Z WITH
FROPA. UNTIL THEN...GUSTY SSWLYS ESP WHERE CLOUDS HAVE CLEARED
THIS PM WITH GUSTS INTO THE MID 20S KTS. AFTER FROPA INTO
TMRW...WINDS SHIFTING AND ULTIMATELY GUSTY NWLYS BY TMRW PM IN
TIGHT GRADIENT AS SURFACE HIGH WORKS INTO UPPER MS VALLEY.
COOLER/DRIER AIR INFILTRATES THEN FOR THE WEEKEND WITH HIGH
PRESSURE IN CONTROL. U30S POSSIBLE SAT NITE AND SUN NITE MAINLY
NORTH.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 157 PM CDT FRI SEP 21 2012
BY MONDAY...THE CENTER OF HIGH PRESSURE WILL BE STARTING TO MOVE
EAST OF THE REGION...AND BECOME SITUATED OVER THE APPALACHAINS BY
00Z TUESDAY. MEANWHILE...SFC WINDS WILL BE VEERING AROUND THE
SOUTH/SOUTHEAST THROUGHOUT THE DAY. MODELS HAVE BEEN ADVERTISING FOR
DAYS NOW...OF PRECIPITATION BREAKING OUT TO OUR WEST...ALONG THE
NOSE OF THE THETA E RIDGE/DEVELOPING WARM FRONT MAINLY ACROSS
MISSOURI...BUT BELIEVE THE MAJORITY OF THE RAIN SHOULD STAY WEST OF
OUR COUNTIES.
HOWEVER...ON MONDAY NIGHT...BOTH THE GFS AND ECMWF SHOW A WEAK
SHORTWAVE IN THE UPPER FLOW THAT MIGHT ACT TO ENHANCE OUR CHANCES
FOR RAIN. THE GFS WEAKENS THIS FEATURE AS IT MOVES IN OUR DIRECTION
AND BOTH THE 06Z AND 12Z RUNS KEEP THE BEST QPF JUST WEST OF OUR
AREA...BUT HINT THAT OUR WESTERN COUNTIES WOULD HAVE THE BEST
CHANCES. THE 00Z ECMWF FAVORS OUR NORTHERN HALF FOR
PRECIPITATION...ESPECIALLY AFTER 06Z...AS IT TAKES THE SHORTWAVE
ACROSS SOUTHERN IL/SOUTHWEST IN.
TUESDAY WILL BE A TRICKY DAY AS THE GFS JUST SHIFTS THE MAIN PRECIP
FOCUS TO OUR NORTH THROUGHOUT THE DAY. THE ECMWF HAS SOME LINGERING
PRECIP IN THE MORNING WITH THE DEPARTING SHORTWAVE AND THEN MAINLY
DRY THE REST OF THE DAY. WE MIGHT END UP JUST BEING WARM SECTORED.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...BOTH THE GFS AND ECMWF
INDICATE MOST OF THE ACTION WILL BE ALONG A FRONTAL BOUNDARY TO OUR
NORTH. SOME OF THOSE SHOWERS/STORMS MAY BLEED INTO OUR NORTHERN
COUNTIES AS THE FRONT SLOWLY SAGS SOUTH...WHICH IS SUPPORTED BY THE
GFS ENSEMBLES. THIS IDEA IS REFLECTED IN THE GOING ZONES...BUT MAY
HAVE TO PULL POPS BACK A BIT GIVEN HOW FAR NORTH THE FRONT IS. THE
I-64 CORRIDOR LOOKS TO BE A GOOD BET RIGHT NOW.
THURSDAY AND BEYOND...THE FORECAST BECOMES EVEN MORE CHALLENGING.
THE GFS AND ECMWF HAVE BEEN SHOWING A LARGE TROUGH ROTATING DOWN
ACROSS THE GREAT LAKES AND UPPER MIDWEST BY TUESDAY NIGHT AND INTO
WEDNESDAY. THE PROBLEM LIES IN THE FACT THAT THE 12Z GFS DOES NOT
CARVE THIS TROUGH AS FAR SOUTH INTO OUR AREA...THEREFORE...THE ZONAL
UPPER FLOW REMAINS IN PLACE AND THE SFC FRONT MOVES SLOWLY SOUTH AND
THEN STALLS DURING THE WEDNESDAY NIGHT THROUGH FRIDAY TIME FRAME.
THE COLD CANADIAN HIGH THAT TRIES TO PRESS DOWN JUST GETS CAUGHT UP
IN THE GREAT LAKES REGION WITH NO WHERE TO GO.
THE 00Z ECMWF SHOWS A MUCH DEEPER TROUGH AND THE UPPER FLOW
BECOMING MORE WEST/NORTHWESTERLY AND THE FRONT COMES THROUGH THE
AREA SOMETIME ON THURSDAY...AND THE SFC HIGH SETTLES IN FURTHER
SOUTH ACROSS OUR AREA FOR FRIDAY. THEREFORE...TEMPERATURE
DIFFERENCES BTWN THE GFS AND ECMWF ARE RATHER LARGE FOR FRIDAY. WILL
PLAY IT SAFE HERE AND GO WITH VERY LOW POPS FOR THURSDAY-FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 556 PM CDT FRI SEP 21 2012
WITH THIS FORECAST ISSUANCE...ATTEMPTED TO ADDRESS CEILING AND
WIND CHANGES WITH THE PASSAGE OF THE COLD FRONT THROUGH EACH OF
THE TAF SITES THIS EVENING. SINCE MOST OF THE CONVECTION WILL
LIKELY IMPACT ONLY THE KEVV AND KOWB TAF SITES THIS EVENING...KEPT
A VICINITY THUNDERSTORM MENTION IN PLACE FOR ONE TO TWO HOURS.
THERE MAY BE SOME CONVECTIVE WIND GUST POTENTIAL NEAR
THUNDERSTORMS...BUT COULD NOT ADDRESS IT IN FINE DETAIL WITH THE
SCHEDULED 00Z SATURDAY ISSUANCE AT THIS TIME.
THE NAM-WRF NUMERICAL MODEL GUIDANCE SUGGESTS SOME POST FRONTAL
MOISTURE TRAPPED UNDER THE INVERSION AT KEVV/KOWB TAF SITES IN THE
06Z TO 16Z SATURDAY TIME FRAME. GIVEN THE DOWNWARD MOTION BEHIND
THE FRONT...CEILINGS MAY NOT MATERIALIZE...BUT WAS UNCERTAIN
ENOUGH WITH THE POTENTIAL FOR WEAK LIFT TO INCLUDE A PERIOD OF IFR
CEILINGS AT THESE LOCATIONS. IF THE NEW MODEL RUNS DIMINISH THIS
POTENTIAL...WILL REMOVE ANY MENTION OF BROKEN IFR CEILINGS.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...SMITH
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
622 PM CDT FRI SEP 21 2012
.UPDATE...
ISSUED AT 556 PM CDT FRI SEP 21 2012
FORECAST UPDATE...18Z NAM 12KM AND 12Z ECMWF SEEM TO HAVE A GOOD HANDLE ON
CURRENT TRENDS. HAVE FOCUSED POPS THIS EVENING OVER THE NORTH 1/2
OF THE AREA WHERE SLIGHTLY DEEPER MOISTURE EXISTS. TEMPERATURES
THROUGH EARLY EVENING WERE UPDATED...AS EXISTING VALUES WERE
COOLING TOO FAST TOO QUICKLY GIVEN THE WINDS AHEAD OF AND WITH THE
FRONT AND CURRENT CONDITIONS. THE RUC AND NAM DNG TEMPS SUPPORT
THIS TREND. ONLY MINOR ADJUSTMENTS TO CLOUDS.
MESOSCALE UPDATE...VISIBLE AND INFRARED SATELLITE TRENDS SHOWED
THE EVOLUTION OF ENHANCED CLOUD TOPS AT 2045Z AROUND THE ST. LOUIS
METRO AREA...WITH THE TRANSITION OF WATER TO ICE CLOUD SHOWING UP
BETWEEN 2300-2330Z TIME FRAME.,,SUGGESTING SHARPER LAPSE RATES
ALOFT TYING IN WITH SURFACE BASED INSTABILITY AND MOISTURE JUST
OUTSIDE THE WFO PAH COUNTIES IN SOUTHERN IL. GOES SOUNDER
PRECIPITABLE WATER VALUES DURING THE PAST HOUR SHOW A GOOD PLUME
OF 1.2 TO 1.5 INCHES OF WATER OVER SOUTHERN ILLINOIS...SPREADING
SOUTH AND IN EAST INTO SOUTHEAST MISSOURI...WEST KENTUCKY AND
SOUTHWEST INDIANA. THE LIMITING FACTOR...BASED ON SURFACE
INSTABILITY...IS SUGGESTED BY THE GOES SOUNDER LIFTED INDEX AROUND
22Z. THE ZERO TO MINUS FOUR VALUES ONLY GO DOWN AS FAR AS ROUTE 13
IN SOUTHERN ILLINOIS. THIS IS CLOSE TO THE 20Z SPC SLIGHT RISK
AREA DEPICTED EARLIER THIS AFTERNOON.
AS THE BOUNDARY LAYER SLOWLY COOLS IN THE WARM SECTOR...ANTICIPATE
SOME GRADUAL REDUCTION IN SURFACE MIXING OF AIR PARCELS...WITH THE
EXCEPTION OF THE COLD FRONTAL BOUNDARY. THIS MAY LEAD TO MORE
UPSHEAR AND ELEVATED CONVECTION ALONG THE FRONT AS IT CONTINUES TO
MOVE EASTWARD INTO SOUTHEAST IL...WEST KENTUCKY AND SOUTHWEST
INDIANA WITH THE MOIST AND SLIGHTLY UNSTABLE AIR MASS. THIS MAY
LIMIT WIND AND SOME HAIL POTENTIAL LATE THIS EVENING IN THESE AREAS.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 157 PM CDT FRI SEP 21 2012
SURFACE LOW IN NE MO...WARM FRONT HAVING ADVANCED ACROSS PAH FA IS
TO OUR NORTH...PM CONVECTION STARTING TO FIRE IN ISOLATED FASHION
NEAR LOW CENTER/ALONG WARM FRONTAL BOUNDARY CENTRAL IL. THIS AREA
BEING CLOSELY MONITORED BY SPC FOR WW...HAIL WOULD BE MAIN THREAT
GIVEN ELEVATED NATURE AND COOLER TEMPS ALOFT.
MODELS THRUST COLD FRONT ACROSS PAH FA THIS EVENING. CONVECTIVE
CHANCES ATTENDANT...BEST NORTHEST...WILL EXPIRE AFT 06Z WITH
FROPA. UNTIL THEN...GUSTY SSWLYS ESP WHERE CLOUDS HAVE CLEARED
THIS PM WITH GUSTS INTO THE MID 20S KTS. AFTER FROPA INTO
TMRW...WINDS SHIFTING AND ULTIMATELY GUSTY NWLYS BY TMRW PM IN
TIGHT GRADIENT AS SURFACE HIGH WORKS INTO UPPER MS VALLEY.
COOLER/DRIER AIR INFILTRATES THEN FOR THE WEEKEND WITH HIGH
PRESSURE IN CONTROL. U30S POSSIBLE SAT NITE AND SUN NITE MAINLY
NORTH.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 157 PM CDT FRI SEP 21 2012
BY MONDAY...THE CENTER OF HIGH PRESSURE WILL BE STARTING TO MOVE
EAST OF THE REGION...AND BECOME SITUATED OVER THE APPALACHAINS BY
00Z TUESDAY. MEANWHILE...SFC WINDS WILL BE VEERING AROUND THE
SOUTH/SOUTHEAST THROUGHOUT THE DAY. MODELS HAVE BEEN ADVERTISING FOR
DAYS NOW...OF PRECIPITATION BREAKING OUT TO OUR WEST...ALONG THE
NOSE OF THE THETA E RIDGE/DEVELOPING WARM FRONT MAINLY ACROSS
MISSOURI...BUT BELIEVE THE MAJORITY OF THE RAIN SHOULD STAY WEST OF
OUR COUNTIES.
HOWEVER...ON MONDAY NIGHT...BOTH THE GFS AND ECMWF SHOW A WEAK
SHORTWAVE IN THE UPPER FLOW THAT MIGHT ACT TO ENHANCE OUR CHANCES
FOR RAIN. THE GFS WEAKENS THIS FEATURE AS IT MOVES IN OUR DIRECTION
AND BOTH THE 06Z AND 12Z RUNS KEEP THE BEST QPF JUST WEST OF OUR
AREA...BUT HINT THAT OUR WESTERN COUNTIES WOULD HAVE THE BEST
CHANCES. THE 00Z ECMWF FAVORS OUR NORTHERN HALF FOR
PRECIPITATION...ESPECIALLY AFTER 06Z...AS IT TAKES THE SHORTWAVE
ACROSS SOUTHERN IL/SOUTHWEST IN.
TUESDAY WILL BE A TRICKY DAY AS THE GFS JUST SHIFTS THE MAIN PRECIP
FOCUS TO OUR NORTH THROUGHOUT THE DAY. THE ECMWF HAS SOME LINGERING
PRECIP IN THE MORNING WITH THE DEPARTING SHORTWAVE AND THEN MAINLY
DRY THE REST OF THE DAY. WE MIGHT END UP JUST BEING WARM SECTORED.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...BOTH THE GFS AND ECMWF
INDICATE MOST OF THE ACTION WILL BE ALONG A FRONTAL BOUNDARY TO OUR
NORTH. SOME OF THOSE SHOWERS/STORMS MAY BLEED INTO OUR NORTHERN
COUNTIES AS THE FRONT SLOWLY SAGS SOUTH...WHICH IS SUPPORTED BY THE
GFS ENSEMBLES. THIS IDEA IS REFLECTED IN THE GOING ZONES...BUT MAY
HAVE TO PULL POPS BACK A BIT GIVEN HOW FAR NORTH THE FRONT IS. THE
I-64 CORRIDOR LOOKS TO BE A GOOD BET RIGHT NOW.
THURSDAY AND BEYOND...THE FORECAST BECOMES EVEN MORE CHALLENGING.
THE GFS AND ECMWF HAVE BEEN SHOWING A LARGE TROUGH ROTATING DOWN
ACROSS THE GREAT LAKES AND UPPER MIDWEST BY TUESDAY NIGHT AND INTO
WEDNESDAY. THE PROBLEM LIES IN THE FACT THAT THE 12Z GFS DOES NOT
CARVE THIS TROUGH AS FAR SOUTH INTO OUR AREA...THEREFORE...THE ZONAL
UPPER FLOW REMAINS IN PLACE AND THE SFC FRONT MOVES SLOWLY SOUTH AND
THEN STALLS DURING THE WEDNESDAY NIGHT THROUGH FRIDAY TIME FRAME.
THE COLD CANADIAN HIGH THAT TRIES TO PRESS DOWN JUST GETS CAUGHT UP
IN THE GREAT LAKES REGION WITH NO WHERE TO GO.
THE 00Z ECMWF SHOWS A MUCH DEEPER TROUGH AND THE UPPER FLOW
BECOMING MORE WEST/NORTHWESTERLY AND THE FRONT COMES THROUGH THE
AREA SOMETIME ON THURSDAY...AND THE SFC HIGH SETTLES IN FURTHER
SOUTH ACROSS OUR AREA FOR FRIDAY. THEREFORE...TEMPERATURE
DIFFERENCES BTWN THE GFS AND ECMWF ARE RATHER LARGE FOR FRIDAY. WILL
PLAY IT SAFE HERE AND GO WITH VERY LOW POPS FOR THURSDAY-FRIDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 556 PM CDT FRI SEP 21 2012
WITH THIS FORECAST ISSUANCE...ATTEMPTED TO ADDRESS CEILING AND
WIND CHANGES WITH THE PASSAGE OF THE COLD FRONT THROUGH EACH OF
THE TAF SITES THIS EVENING. SINCE MOST OF THE CONVECTION WILL
LIKELY IMPACT ONLY THE KEVV AND KOWB TAF SITES THIS EVENING...KEPT
A VICINITY THUNDERSTORM MENTION IN PLACE FOR ONE TO TWO HOURS.
THERE MAY BE SOME CONVECTIVE WIND GUST POTENTIAL NEAR
THUNDERSTORMS...BUT COULD NOT ADDRESS IT IN FINE DETAIL WITH THE
SCHEDULED 00Z SATURDAY ISSUANCE AT THIS TIME.
THE NAM-WRF NUMERICAL MODEL GUIDANCE SUGGESTS SOME POST FRONTAL
MOISTURE TRAPPED UNDER THE INVERSION AT KEVV/KOWB TAF SITES IN THE
06Z TO 16Z SATURDAY TIME FRAME. GIVEN THE DOWNWARD MOTION BEHIND
THE FRONT...CEILINGS MAY NOT MATERIALIZE...BUT WAS UNCERTAIN
ENOUGH WITH THE POTENTIAL FOR WEAK LIFT TO INCLUDE A PERIOD OF IFR
CEILINGS AT THESE LOCATIONS. IF THE NEW MODEL RUNS DIMINISH THIS
POTENTIAL...WILL REMOVE ANY MENTION OF BROKEN IFR CEILINGS.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...SMITH/CTN
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
423 AM EDT THU SEP 20 2012
.SYNOPSIS...
HIGH PRESSURE WILL ALLOW FOR DRY WEATHER TO CONTINUE UNTIL THE
APPROACH OF A STRONG COLD FRONT LATE ON FRIDAY. IN THE WAKE OF THE
FRONT, MUCH COOLER AIR WILL SETTLE INTO THE REGION SATURDAY
THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A
RELATIVELY DRY SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. AT THE
SURFACE, A 1026MB HIGH IS CENTERED ACROSS MAINE WITH A 998MB
SURFACE LOW JUST NORTHWEST OF LAKE SUPERIOR. A COLD FRONT EXTENDS
SOUTHWARD OF THE LOW ACROSS ILLINOIS AND INTO THE MISSOURI VALLEY.
WELL AHEAD OF THE FRONT, SKIES REMAIN CLEAR WITH NEAR CALM WINDS
ACROSS THE UPPER OHIO VALLEY.
TODAY AND TONIGHT...THE TROUGH WILL MOVE EASTWARD INTO THE GREAT LAKES
REGION WITH THE COLD FRONT SWINGING INTO THE OHIO VALLEY AND
AIDING WARM AIR ADVECTION. WITH A DEEP LAYER OF DRY AIR IN PLACE, SKIES
WILL BE SUNNY UNTIL LATE IN THE DAY AS MOISTURE ALONG THE WEAK
COLD FRONT ADVECTS ACROSS THE AREA AND INCREASES CLOUDINESS
OVERNIGHT. A THERMAL RIDGE WILL BUILD INTO THE AREA TODAY WITH
WAA (850MB TEMPS INCREASING FROM 6C TO 12C). THIS IN COMBINATION
WITH ABUNDANT SUNSHINE WILL ALLOW TEMPS TO BE AROUND 10 DEGREES
WARMER IN COMPARISON TO WEDNESDAY. HIGHS WILL WARM INTO THE LOWER
70S ACROSS MOST OF THE LOWLANDS, WITH MID 60S ANTICIPATED FOR THE
HIGHER ELEVATIONS IN THE EASTERN RIDGES. LOWS TONIGHT WILL BE NEAR
SEASONAL NORMALS, IN THE LOWER 50S ACROSS MUCH OF THE AREA, AS
CLOUD COVERAGE INHIBITS RADIATIONAL COOLING.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
GFS/NAM ARE IN AGREEMENT THAT A STRONG COLD FRONT WILL CROSS THE
OHIO VALLEY ON FRIDAY AND REACH THE EASTERN OHIO ZONES BY 06Z ON
SATURDAY. THE FRONT WILL PUSH INTO WESTERN PA SATURDAY MORNING AND
CLEAR THE EASTERN RIDGES BY SATURDAY EVENING. LIKELY POPS ARE
FORECAST WITH THE PASSAGE OF THE FRONT WITH SCHC THUNDER IN WEAK
SURFACE-BASED INSTABILITY ALONG AND SOUTH OF THE MASON-DIXON LINE.
THE CHANCE OF SHOWERS WILL LINGER BEHIND THE FRONT ON SATURDAY AS
500MB HEIGHTS CONTINUE TO LOWER AND THE BEST MID-LEVEL FORCING
WITH THE TROUGH PUSHES INTO THE AREA. THE HIGHEST QPF (QUARTER TO
HALF OF AN INCH) IS FOCUSED NORTHWEST OF PITTSBURGH AS STRONGER
1000MB-700MB FRONTOGENETICAL FORCING CROSSES THIS AREA FRIDAY
NIGHT. ELSEWHERE, LESS THAN A QUARTER OF AN INCH OF RAINFALL IS
FORECAST WITH THE FRONTAL PASSAGE.
SATURDAY NIGHT INTO SUNDAY...OPERATIONAL MODELS ARE IN AGREEMENT
THAT THE MID-LEVEL TROUGH AXIS WILL SWING ACROSS THE AREA WITH THE
REINFORCEMENT OF FORCING FROM A SHORT WAVE ALONG WITH ONGOING COLD
AIR ADVECTION. THUS, THE CHANCE OF SHOWERS CONTINUES FOR LOCATIONS
PRIMARILY NORTH OF PITTSBURGH AND ACROSS THE EASTERN RIDGES.
FOR TEMPERATURES, HIGHS ON FRIDAY LEAN CLOSER TO THE SLIGHTLY WARMER
ECMWF GUIDANCE IN WAA AHEAD OF THE COLD FRONT. WITH THE FRONTAL
PASSAGE, LOW TEMPS ARE A GFS/ECMWF BLEND, AROUND 5 DEGREES ABOVE
NORMAL AHEAD OF THE FRONT ON FRIDAY NIGHT DECREASING TO AROUND 5
DEGREES BELOW NORMAL IN THE WAKE OF THE FRONT. FOR HIGHS, A CANADIAN
AIR MASS WILL BE ADVECTING INTO THE AREA IN THE WAKE OF THE FRONT
ON SATURDAY AND BUILD INTO THE AREA BY SUNDAY. THUS, TEMPS WILL BE
FAIRLY STEADY IN THE MID 60S BEHIND THE FRONT ON SATURDAY AND ONLY
REACHING THE LOWER 60S ACROSS MOST OF THE AREA ON SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
BLEND OF RECENT NAEFS AND ECMWF ENSEMBLE MODEL OUTPUT SHOW A COLD
UPPER LEVEL TROUGH PASSING EXITING EAST MONDAY WITH HIGH PRESSURE
FOLLOWING TUESDAY AND WEDNESDAY.
RESULTING COLD POOL INSTABILITY SUNDAY WILL YIELD AT LEAST
AFTERNOON CLOUDINESS ACROSS MUCH OF THE UPPER OHIO VALLEY SUNDAY
WITH SCATTERED SHOWERS NORTH AND NEAR THE MOUNTAINS.
EXPECT LESS CLOUDS MONDAY WITH FAIRLY CLEAR SKIES TUESDAY AND
WEDNESDAY.
JUDGING FROM NAEFS MEDIAN VALUES AND ECMWF MOS...FORECASTED HIGH
TEMPERATURES TO BE ABOUT 10 DEGREES COLDER THAN NORMAL SUNDAY...THEN
SLOWLY WARMING TO BE NEAR NORMAL WEDNESDAY.
FORECASTED LOW TEMPERATURES TO REMAIN 5 TO 10 DEGREES COLDER THAN
NORMAL EACH MORNING.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
EXPECT VFR THROUGH TODAY...DUE TO HIGH PRESSURE SUBSIDENCE WITH
GENERALLY CLEAR SKIES AND SOME DAYTIME SCATTERED CUMULUS CLOUDS.
PATCHES OF RIVER VALLEY FOG CAN FORM EARLY THIS MORNING BUT ITS
TOO DRY TO SPREAD VISIBILITY RESTRICTIONS TO ANY OF THE UPLAND TAF
SITES.
.OUTLOOK /FRIDAY THROUGH MONDAY/...
EXPECT VFR FRIDAY TO BECOME PUNCTUATED BY RESTRICTIONS FRIDAY
AFTERNOON INTO SUNDAY AFTERNOON DUE TO SHOWERS ASSOCIATED WITH A
COLD FRONTAL PASSAGE FRIDAY NIGHT AND COLD UPPER TROUGH THIS
WEEKEND. EXPECT TREND TOWARD PREVALENT VFR MONDAY AS LAST OF
STRATOCUMULUS CEILINGS LIFT OR DISSIPATE.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MDZ001.
OH...NONE.
PA...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ009.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
LONG TERM...
AVIATION...
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
229 AM EDT THU SEP 20 2012
.SYNOPSIS...
HIGH PRESSURE WILL ALLOW FOR DRY WEATHER TO CONTINUE UNTIL THE
APPROACH OF A STRONG COLD FRONT LATE ON FRIDAY. IN THE WAKE OF THE
FRONT, MUCH COOLER AIR WILL SETTLE INTO THE REGION SATURDAY
THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
06Z ENHANCED SHORT TERM FORECAST HAS BEEN ISSUED TO ACCOUNT FOR
THE LATEST TEMP TRENDS. THE FROST ADVISORY REMAINS IN PLACE FOR
FOREST AND GARRETT COUNTIES.
THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A
RELATIVELY DRY SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. AT THE
SURFACE, A 1026MB HIGH IS CENTERED ACROSS MAINE WITH A 998MB
SURFACE LOW JUST NORTHWEST OF LAKE SUPERIOR. A COLD FRONT EXTENDS
SOUTHWARD OF THIS FEATURE ACROSS ILLINOIS AND INTO THE MISSOURI
VALLEY. WELL AHEAD OF THE FRONT, SKIES REMAIN CLEAR WITH NEAR CALM
WINDS ACROSS THE UPPER OHIO VALLEY.
TODAY...THE TROUGH WILL MOVE EASTWARD INTO THE GREAT LAKES REGION
WITH THE COLD FRONT WILL SWINGING INTO THE OHIO VALLEY AND A WEAK
WARM FRONT PUSHING NORTH OF THE AREA. WITH A DEEP LAYER OF DRY AIR
IN PLACE, SKIES WILL BE SUNNY UNTIL LATE IN THE DAY AS MOISTURE
ALONG THE WEAK COLD FRONT ADVECTS INTO THE AREA. A THERMAL RIDGE
WILL BUILD INTO THE AREA TODAY WITH WARM AIR ADVECTION TAKING
PLACE (850MB TEMPS INCREASING FROM 6C TO 12C). THIS IN COMBINATION
WITH ABUNDANT SUNSHINE WILL ALLOW TEMPS TO BE AROUND 10 DEGREES
WARMER IN COMPARISON TO WEDNESDAY. HIGHS WILL WARM INTO THE LOWER
70S ACROSS MOST OF THE LOWLANDS, WITH MID 60S ANTICIPATED FOR THE
HIGHER ELEVATIONS IN THE EASTERN RIDGES.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY/...
THE AFOREMENTIONED CDFNT IS PROJECTED TWD THE UPR OH ON THU...BUT
WITH A LACK OF RAIN-SUPPORTING MSTR. EXPECT AN INCREASE IN CLOUDS
WITH MODERATING TEMPS IN THE WARM ADVCTN IN ADVN OF THE FRONT.
A MUCH STRONGER SYSTEM IS PROGGED TO MOVE THROUGH THE UPPER MIDWEST
FRIDAY. THAT DISTURBANCE WL FURTHER AMPLIFY THE BROAD ERN NORTH
AMERICAN TROF AND WL LIKELY SPAWN SOME SHRA OVR NWRN ZONES BY LATE
AFTN OR EVE. CHC POPS WERE CONTD FOR THE OVRNGT PD AND INTO
SATURDAY AS THE MAIN MID LVL TROF AXIS AND COLD POOL ENCROACH OVR
THE AREA.
MUCH COLDER TEMPS SHOULD BE EXPECTED IN THE WAKE OF THIS PARTICULAR
FRONT...FORECAST WAS CONSTRUCTED WITH A LEAN TWD THE COOLER NAM.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
BLEND OF RECENT NAEFS AND ECMWF ENSEMBLE MODEL OUTPUT SHOW A COLD
UPPER LEVEL TROUGH PASSING EASTWARD THROUGH THE GREAT LAKES AND
UPPER OHIO VALLEY SUNDAY...EXITING EAST MONDAY WITH HIGH PRESSURE
FOLLOWING TUESDAY AND WEDNESDAY.
RESULTING COLD POOL INSTABILITY SUNDAY WILL YIELD AT LEAST
AFTERNOON CLOUDINESS ACROSS MUCH OF THE UPPER OHIO VALLEY SUNDAY
WITH SCATTERED SHOWERS NORTH AND NEAR THE MOUNTAINS.
EXPECT LESS CLOUDS MONDAY WITH FAIRLY CLEAR SKIES TUESDAY AND
WEDNESDAY.
JUDGING FROM NAEFS MEDIAN VALUES AND ECMWF MOS...FORECASTED HIGH
TEMPERATURES TO BE ABOUT 10 DEGREES COLDER THAN NORMAL SUNDAY...THEN
SLOWLY WARMING TO BE NEAR NORMAL WEDNESDAY.
FORECASTED LOW TEMPERATURES TO REMAIN 5 TO 10 DEGREES COLDER THAN
NORMAL EACH MORNING.
&&
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
EXPECT VFR THROUGH THURSDAY...DUE TO HIGH PRESSURE SUBSIDENCE WITH
GENERALLY CLEAR SKIES AND SOME DAYTIME SCATTERED CUMULUS CLOUDS.
PATCHES OF RIVER VALLEY FOG CAN FORM EARLY THURSDAY MORNING BUT ITS
TOO DRY TO SPREAD VISIBILITY RESTRICTIONS TO ANY OF THE UPLAND TAF
SITES.
.OUTLOOK /FRIDAY THROUGH MONDAY/...
EXPECT VFR FRIDAY TO BECOME PUNCTUATED BY RESTRICTIONS FRIDAY
AFTERNOON INTO SUNDAY AFTERNOON DUE TO SHOWERS ASSOCIATED WITH A
COLD FRONTAL PASSAGE FRIDAY NIGHT AND COLD UPPER TROUGH THIS
WEEKEND. EXPECT TREND TOWARD PREVALENT VFR MONDAY AS LAST OF
STRATOCUMULUS CEILINGS LIFT OR DISSIPATE.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MDZ001.
OH...NONE.
PA...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ009.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...
LONG TERM...
AVIATION...
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
742 PM EDT FRI SEP 21 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 458 PM EDT FRI SEP 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A DEEP MID/UPPER LEVEL TROUGH
FROM HUDSON BAY INTO THE WRN GREAT LAKES. THE SHRTWV THAT BROUGHT AN
AREA OF RAIN AND SOME TSRA TO UPPER MI THIS MORNING HAS MOVED
QUICKLY EAST OF LAKE SUPERIOR. ANOTHER VIGOROUS UPSTREAM SHRTWV/VORT
WAS LOCATED JUST SE OF LAKE WINNIPEG. SOME LIGHTNING HAS ALSO
ACCOMPANIED A LINE OF SHOWERS AHEAD OF THIS FEATURE. AT THE
SFC...LOW PRES WAS LOCATED OVER ERN LAKE SUPERIOR. THE COLD FRONT
ASSOCIATED WITH THE UPSTREAM SHRTWV HAS MOVED INTO THE NW CORNER OF
MN HAS BRINGING VERY GUSTY WINDS TO AROUND 35KT IN ITS WAKE. RADAR
INDICATED SCT SHOWERS LINGERING OVER THE AREA SUPPORTED BY SHALLOW
INSTABILITY AND LAKE MOISTURE AS 850/700 MB TEMPS REMAIN NEAR
0C/-10C.
TONIGHT...EXPECT A BRIEF PERIOD OF MORE LIMITED SHRA COVERAGE THIS
EVENING AS THE LOW LEVEL TROUGH AND BATCH OF SHRA OVER CNTRL UPPER
MI MOVES TO THE EAST. HOWEVER SOME LAKE ENHANCED SHOWERS SHOULD
STILL LINGER NEAR AREAS FAVORED BY NW FLOW. SATELLITED TRENDS AND
MODELS SUGGEST THAT THE MAIN IMPACTS OF THE MANITOBA SHRTWV WILL
SLIDE WELL TO THE WEST AND SOUTH OF UPPER MICHIGAN. HOWEVER...AS IT
MOVES TO THE SOUTH WINDS WILL VEER MORE NRLY AND COLDER AIR WILL
PUSH INTO THE AREA. LAKE EFFECT SHOWERS SHOULD THEN INCREASE FOR N
FLOW AREAS AS 850 MB TEMPS FALL TO AROUND -2C.
SATURDAY...THE BULK OF THE COLDER AIR MOVES IN WITH 850/700 MB TEMPS
FALLING TO AROUND -3C/-12C. NAM FCST SOUNDINGS SUGGEST THAT LAKE
INDUCED CAPE MAY CLIMB INTO THE 500-1000 J/KG RANGE. EXPECT HEAVIEST
PCPN OVER LOCATIONS FAVORED BY NNW FLOW...ESPECIALLY OVER N CNTRL INTO E
UPPER MI. ALTHOUGH LIGHTNING WOULD BE UNUSUAL WITH LAKE EFFECT
PCPN...WITH THE VERY COLD AIR ALOFT (500 MB TEMP TO -30C) CANNOT
RULE OUT SOME ISOLD TSRA AS WAS OBSERVED THIS MORNING. SIMILAR TO
THE LAST FEW DAYS...PERIODS OF GRAUPEL/SLEET MAY ALSO ACCOMPANY THE
HEAVIER SHOWERS. WITH WET-BULB ZERO HEIGHTS DOWN TO NEAR 1500 FT
AGL. SOME SNOW COULD BE POSSIBLE OVER HIGHER TERRAIN BUT WOULD
LIKELY BE VERY TRANSIENT/BRIEF. GALES OVER LAKE SUPERIOR WILL ALSO
BRING SOME STRONGER WINDS TO SHORELINE LOCATIONS POSSIBLY REACHING
ADVY CRITERIA (45 MPH GUSTS) AT THE MOST EXPOSED LOCATIONS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 458 PM EDT FRI SEP 21 2012
SAT NGT...A HEALTHY LAKE EFFECT/ENHANCED SHRA REGIME WL CONT WITH
DEEP CYC NW FLOW OF CHILLY AIR /H85 TEMPS -3 TO -5C/ UNDER
PERSISTENT SHARP UPR TROF AXIS...ESPECIALLY FOR THOSE AREAS ON THE
CYC SIDE OF TRACK OF SHRTWV THAT IS FCST TO DIG SHARPLY THRU THE NNW
FLOW ALF. GIVEN THE INTENSITY OF THE TROF AND LOCATION OF H3 UPR JET
AXIS THRU MN/WI...PREFER THOSE MODELS THAT SHOW A FARTHER W TRACK
FOR THIS DISTURBANCE. RETAINED MENTION OF TS OVER MAINLY AREAS NEAR
THE E HALF OF LK SUP WHERE NAM SHOW SBCAPE UP TO 300-400 J/KG.
NOT OUT OF THE QUESTION THAT ANY -SHRA OVER THE INTERIOR W COULD MIX
WITH SN OVER THE HIER TERRAIN LATER AT HGT IN PRESENCE OF DIURNAL
COOLING/MIN TEMPS FALLING CLOSE TO 32 AS 12Z NAM SHOWS H100-85 THKNS
AND WBZ HGT FALLING TO 1300-1305M/NEAR 1K FT AGL. WITH MORE OF A
LAKE WARMING INFLUENCE ELSEHWERE...PTYPE WL BE RA...BUT DID RETAIN
MENTION OF MIX WITH SLEET/GRAUPEL FOR AREAS IMPACTED BY SOME HEAVIER
SHRA.
SUN...AS CLOSED LO/CORE OF COLD MID LVL TEMPS LIFTS NEWD INTO
QUEBEC...MODELS SHOW SLOWLY RISING HGTS UNDER LARGER SCALE DNVA/
SINKING INVRN BASE/RISING H85 OVER THE UPR LKS. SINCE THE LLVL FLOW
IS PROGGED TO BACK MORE W AND ADVECT DRIER LLVL AIR INTO THE AREA AS
SFC HI PRES CENTER SINKS TOWARD THE MID MS RIVER VALLEY LATE IN THE
DAY IN THE PRESENCE OF DIURNAL HEATING THAT WL DISRUPT THE LAKE
EFFECT PROCESS...EXPECT STEADILY DCRSG POPS THAT WL LINGER LONGEST
DOWNWIND OF LK SUP E OF MQT WHERE LOWER H85 TEMPS AND LLVL
MOISTENING OF THE DRIER FLOW WL BE MORE PERSISTENT.
SUN NGT...DNVA/LOWERING INVRN BASE AND BACKING/DRYING FLOW TO WSW
BTWN HI PRES MOVING INTO THE OH RIVER VALLEY AND SHRTWV DIGGING SEWD
FM MANITOBA WL CONSPIRE TO FINALLY DIMINISH ANY LINGERING LK EFFECT
PCPN OVER THE E. DESPITE PARTIAL CLEARING BEFORE SOME MID/HI CLDS IN
ADVANCE OF APRCHG SHRTWV ARRIVE...LLVL WARMING/STEADY WSW FLOW THAT
MAINTAINS SOME MIXING WL RESTRICT DIURNAL TEMP FALL DESPITE PWAT
FALLING AS LO AS 0.30 INCH. WHERE THE PRES GRADIENT IS SLOWER TO
TIGHTEN UP AND CLDS ARRIVE LATER NEAR THE WI BORDER...MIN TEMPS MAY
APRCH 32.
MON...SHRTWV EMBEDDED IN NW FLOW ALF ON WRN FLANK OF SLOWLY
RETREATING UPR TROF IS PROGGED TO SWING SEWD THRU ONTARIO. ALTHOUGH
SOME OF THE MORE IMPRESSIVE DVPA/DEEP LYR QVECTOR CNVGC IS PROGGED
TO BRUSH MAINLY THE NE HALF OF THE CWA...DRYNESS OF FCST SDNGS/
ABSENCE OF ANY LLVL MSTR ADVECTION INDICATE ANY SHRA WL BE FEW AND
FAR BTWN. MAINTAINED THEME OF LO CHC POPS OVER PORTIONS OF THE NE
CWA CLOSER TO MORE IMPRESSIVE DYNAMICS. WARMING H85 TEMPS IN STEADY
WSW FLOW AHEAD OF ATTENDANT COLD FNT WL PUSH MAX TEMPS ABV
NORMAL...BUT GUSTY SFC WINDS WL MAKE THE AIR FEEL COOLER. MIXING TO
H85 ON GFS FCST SDNGS INDICATES MAX TEMPS WL RISE INTO THE 60S AT
MOST SPOTS.
MON NGT THRU TUE NGT...AS LO PRES TROF CROSSES THE CWA ON MON NGT
WITH WSHFT TO THE N...WENT WITH LO CHC POPS MAINLY IN THE UPSLOPE
AREAS NEAR LK SUP. THEN TRAILING HI PRES MOVING IN FM CNTRL CAN WL
BRING A PERIOD OF DRY WX ON TUE. BUT AS COOLER AIR /WITH H85 TEMPS
DROPPING AOB 0C/ ARRIVES ON TUE NGT...SOME LK EFFECT PCPN MAY DVLP
MAINLY OVER THE NCNTRL IN AREAS FAVORED BY FCST LLVL NLY FLOW. AWAY
FM THE MODERATING INFLUENCE OF LK SUP AND CLOSER TO INCOMING HI PRES
CENTER BLDG INTO MN...TENDED BLO GUIDANCE FOR MIN TEMPS TOWARD 32
OVER THE INTERIOR W.
EXTENDED...SFC HI PRES IS FCST TO DOMINATE UNDER RISING HGTS AS UPR
TROF IN CAN SLOWLY LIFTS TO THE NE. EXPECT DRY WX THRU THIS PERIOD
WITH WIDE DIURNAL TEMP VARIATIONS...ESPECIALLY OVER THE INTERIOR
AWAY FM THE MODERATING INFLUENCE OF THE LKS. OVERALL HOWEVER...TEMPS
SHOULD AVG BLO NORMAL DURING THIS TIME.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 741 PM EDT FRI SEP 21 2012
A SERIES OF SHORTWAVES WILL ROTATE THROUGH THE AREA AROUND A LARGE
UPPER TROUGH IN PLACE OVER THE REGION. THROUGH THIS
EVENING...CONDITIONS SHOULD STAY VFR OR MAYBE HIGH END MVFR. WINDS
WILL TURN MORE NORTHERLY THROUGH THE TAF PERIOD...RESULTING IN
REDUCED CIGS AND MORE RAIN SHOWERS AT ALL SITES LATER TONIGHT INTO
SATURDAY. IT APPEARS CONDITIONS WILL BE WORST AT SAW DUE TO MORE
EXPOSURE FROM N WINDS. WINDS WILL PICK UP ON SATURDAY...HIGHEST AND
SAW AND CMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 PM EDT FRI SEP 21 2012
A LAKE ENHANCED LOW OVER ERN LAKE SUPERIOR WILL BE SLOW TO MOVE
OFF LK SUPERIOR TONIGHT WHILE HIGH PRESSURE RIDGE BUILDS FROM SCNTRL
CANADA INTO THE NORTHERN PLAINS. THE PRESSURE GRADIENT WILL TIGHTEN
AND EXPECT NNW WINDS TO INCREASE TO GALES LATE TONIGHT OVER NORTH
CENTRAL SECTIONS OF LK SUPERIOR. THERE IS A RISK OF WATERSPOUTS
TONIGHT...PER NOMOGRAM OUTPUT...AS VERY COLD AIR MOVES OVER THE
RELATIVELY WARM WATER BEFORE THE WINDS INCREASE.
GALES ARE EXPECTED SAT INTO SAT EVENING FOR THE CNTRL AND EAST
PORTIONS OF LAKE SUPERIOR AS THE SFC LOW DEEPENS TO THE E AND COLDER
AIR MOVES OVER THE LAKE...CREATING A VERY UNSTABLE TEMP PROFILE.
EXPECT WINDS ON SAT NIGHT INTO SUN NIGHT TO SLOWLY DIMINISH AND
GRADUALLY BACK TO THE W AS A HI PRES CENTER MOVES FROM THE NORTHERN
PLAINS INTO THE OHIO RIVER VALLEY. ANOTHER ROUND OF WSW GALES IS
POSSIBLE LATE SUN NIGHT INTO MON AS THE PRES GRADIENT TIGHTENS
BETWEEN THE RETREATING HI TO THE SE AND ANOTHER LO PRES TROF
DROPPING SEWD FROM CENTRAL CANADA THRU ONTARIO TOWARD LAKE SUPERIOR.
FOLLOWING THE PASSAGE OF THIS TROF ON MON...WINDS WILL DIMINISH AND
VEER TO THE N AHEAD OF HI PRES APPROACHING FROM THE NW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 2 PM SATURDAY TO 1 AM EDT SUNDAY FOR LSZ251-
267.
GALE WARNING FROM 6 AM SATURDAY TO 1 AM EDT SUNDAY FOR LSZ244-
245-248>250-264>266.
GALE WARNING FROM 6 AM TO 2 PM EDT SATURDAY FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...TITUS
MARINE...JLB/KC
AREA FORECAST DISCUSSION
NWS DULUTH MN
1002 PM CDT FRI SEP 21 2012
.UPDATE...
A SPOTTER NEAR CHISHOLM HAD REPORTED THE RAIN HAD SWITCHED OVER TO
SNOW...WITH A QUARTER INCH OF ACCUMULATION. RAP AND NAM BOTH SHOW
LOWEST FREEZING LEVELS ACROSS THE NORTH...AND SINK IT SOUTH AND
WEST OVER THE NEXT FEW HOURS...THEN ACTUALLY INCREASE FREEZING
LEVELS LATE TONIGHT. KHIB/KEVM OBSERVATIONS HAVE ALSO SWITCHED
TO SNOW...AT LEAST BRIEFLY. WE WILL UPDATE AND EXPAND COVERAGE OF
SNOW. WE STILL THINK ACCUMULATIONS WILL BE QUITE LIMITED AS THE
GROUND SHOULD MELT MUCH OF THE SNOW...PERHAPS WITH SOME MINOR
ACCUMULATION ON GRASSY SURFACES/DECKS.
&&
.PREV DISCUSSION... /ISSUED 829 PM CDT FRI SEP 21 2012/
UPDATE...
SURFACE TEMPS DROPPING QUICKLY THIS EVENING...WITH SEVERAL OBS
FROM 36-39 DEGREES FROM PINE RIVER TO CRANE LAKE AND INTERNATIONAL
FALLS. A SPOTTER NEAR BLACKDUCK REPORTED SOME SLEET...AND AFTER
LOOKING AT LOW LEVEL TEMPERATURES WE FEEL THAT IS A THREAT OVER
PORTIONS OF OUR NORTHERN CWA THIS EVENING. THE ONE DRAW BACK FOR
US WILL BE PRECIP RATES...AS THEY HAVE COME DOWN AS THE MORE
CONVECTIVE SHOWERS WERE OCCURRING FURTHER EAST. WE EXPANDED THE
CHANCE FOR SNOW SHOWERS LATER TONIGHT FURTHER SOUTH INTO THE
BRAINERD LAKES REGION...GIVEN COLDER 925MB FORECAST DOWN THERE. WE
DON`T EXPECT ANY SNOW ACCUMULATION GIVEN SURFACE TEMPS EXPECTED TO
BE AT OR ABOVE FREEZING FOR MOST AREAS...AND WARM GROUND
TEMPERATURES.
PREV DISCUSSION... /ISSUED 638 PM CDT FRI SEP 21 2012/
AVIATION...00Z TAFS
STRONG UPPER LOW WILL CONTINUE TO MOVE SOUTHEAST OVER THE
NORTHLAND TONIGHT...WITH AREAS OF SHOWERS AND PERHAPS A
THUNDERSTORM. 23Z SURFACE CHART SHOWED 3.5MB PRESSURE RISES PER 3
HOURS JUST NORTHWEST OF THE NORTHLAND MOVING SOUTH. THE
COMBINATION OF THE PRESSURE RISES AND GUSTY WINDS WITH THE
SHOWERS...WERE CAUSING SOME GUSTS OF 30-45 MPH THIS EVENING. WE
HAVE GUSTY WINDS IN SEVERAL OF THE TAFS FOR THE NEXT COUPLE
HOURS. WE`VE ALSO HAD REPORTS OF PEA SIZE HAIL THIS
AFTERNOON/EVENING...AND THAT WILL BE POSSIBLE WITH THE STRONGER
SHOWERS/THUNDERSTORMS. MVFR CEILINGS/VSBYS WILL ALSO ACCOMPANY
SOME OF THE SHOWERS...AND A GENERAL LOWERING OF THE CEILINGS TO
MVFR IS EXPECTED OVERNIGHT AT MOST TAF SITES.
THE MAIN SHORTWAVE WILL BE EAST OF THE NORTHLAND SATURDAY...WITH
THE MODELS SHOWING SOME DRYING OCCURRING. WE EXPECT CEILING TO
INCREASE SATURDAY...BUT WITH SUCH COLD AIR OVERHEAD...WE DO EXPECT
A CU DECK TO FORM. GUSTY NORTHERLY WINDS ARE EXPECTED
TONIGHT...BUT AGAIN SATURDAY.
UPDATED...
WE ADDED ISOLATED THUNDERSTORMS TO PORTIONS OF THE NORTHLAND AS
THERE WERE STILL SOME LIGHTNING STRIKES OCCURRING OVER PORTIONS OF
FAR NORTHEAST MINNESOTA. WE ALSO ADDED SOME HIGHER GUSTS TO THE
TEXT OF THE ZFP WE`VE SEVERAL OBSERVATIONS REPORTS GUSTS TO 35-45
MPH THIS AFTERNOON/EVENING. NICE AREA OF 3.5MB PRESSURE RISES
MOVING SOUTH OUT OF MB/OT.
PREV DISCUSSION... /ISSUED 308 PM CDT FRI SEP 21 2012/
SHORT TERM...TONIGHT THROUGH SUNDAY MORNING...CURRENT SURFACE ANALYSIS
INDICATE RAIN SHOWERS ASSOCIATED WITH A SHORTWAVE MOVING SE
THROUGH SOUTHERN CANADA ACROSS NORTHERN MINNESOTA AND A PORTION
OF NORTHWEST WISCONSIN. SOME OF THESE CELLS HAVE HAD REPORTS OF
PEA TO DINE SIZE HAIL/GRAUPEL. THIS ACTIVITY WILL CONTINUE SPREAD
SOUTHEAST THIS AFTERNOON AND EVENING AS THE SHORTWAVE MOVES INTO
MINNESOTA. THE SCATTERED SHOWERS WILL CONTINUE TONIGHT ACROSS THE
FORECAST AREA. ONE QUESTIONS FOR TONIGHT WILL BE THE POSSIBILITY
OF SNOW BEING MIXED IN WITH THE RAIN. MODELS INDICATE THICKNESSES
WILL BE COLD ENOUGH FOR SNOW WITH THE BEST SHOW NORTH OF HIGHWAY 2
IN MN. THE PRECIP WILL END ACROSS MN EARLY SATURDAY MORNING BUT
MAY LINGER IN EASTERN PORTIONS OF NW WI WHERE SOME LAKE EFFECT
SHOWERS MAY BE POSSIBLE AND THE INFLUENCE OF THE SHORTWAVE ACROSS
THE AREA.
THE NEXT CONCERN FOR THE SHORT TERM WILL BE HARD FREEZE CHANCE
SATURDAY NIGHT. SKIES WILL CLEAR OUT SATURDAY AFTERNOON AND IT WILL
BE MAINLY CLEAR SATURDAY NIGHT. MODELS INDICATE TEMPS TO BE IN THE
MIDDLE TO UPPER 20S WITH DRIER AIR ACROSS MOST AREAS SUNDAY
MORNING. WILL ISSUE A FREEZE WATCH FOR AREA SOUTH OF HIGHWAY 2 IN
MN AND ALL OF NW WI FOR SUNDAY MORNING. THESE TEMPS WILL END THE
GROWING SEASON ACROSS THE FORECAST AREA.
LONG TERM...SUNDAY THROUGH FRIDAY...THIS TIME PERIOD WILL BE A REALLY
QUIET TIME ACROSS THE NORTHLAND. THE UPPER LEVEL PATTERN WILL
GRADUALLY TRANSITION FROM A MEAN TROUGH ACROSS THE GREAT LAKES TO A
MEAN RIDGE BY WEDNESDAY. IT LOOKS LIKE THERE WILL BE PLENTY OF
SUNSHINE AND TEMPERATURES RANGING FROM THE 50S TO LOWER 60S
THROUGHOUT THE PERIOD. A FEW BACK DOOR COLD FRONTS WILL TRY TO MAKE
SOME PROGRESSION INTO THE AREA DURING THE EARLY PART OF THE WORK
WEEK...BUT UPPER LEVEL RIDGING WILL EVENTUALLY WIN OUT TOWARD THE
MIDDLE OF THE WEEK. THE PATTERN WILL THEN CHANGE ONCE AGAIN TOWARD
THE VERY END OF THE WORK WEEK...AS A MEAN UPPER LEVEL TROUGH PATTERN
ONCE AGAIN DEVELOPS. OVERALL IT LOOKS DRY FOR ALL OR NEARLY ALL OF
THE EXTENDED TIME PERIOD.
&&
.POINT TEMPS/POPS...
DLH 36 50 29 54 / 90 30 0 0
INL 32 48 23 54 / 70 10 0 0
BRD 36 51 28 57 / 60 20 0 0
HYR 36 52 27 54 / 70 40 10 0
ASX 40 53 31 52 / 70 60 40 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
MNZ033>038.
WI...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
WIZ001>004-006>009.
LS...SMALL CRAFT ADVISORY UNTIL NOON CDT SUNDAY FOR LSZ121-146>148.
&&
$$
SHORT TERM...MELDE
LONG TERM....DAP
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
913 PM CDT FRI SEP 21 2012
.DISCUSSION...
MAIN CONCERN FOR THE EVENING UPDATE HAS BEEN WRANGLING WITH NPW
HEADLINES. WINDS HAVE GONE DOWN BELOW ADVISORY CRITERIA ACROSS THE
ENTIRE CWA...SO WILL CANCEL THE WIND ADVISORY A BIT EARLY. THE
WINDS WILL CONTINUE TO DIMINISH DOWN BELOW 10 KTS IN THE WESTERN
CWA AS THE HIGH DROPS DOWN INTO CENTRAL ND...WHILE THE LOW OVER
ONTARIO WILL KEEP THE GRADIENT FAIRLY TIGHT OVER THE EASTERN
COUNTIES. THERE IS ALSO SOME CLOUD COVER ROTATING DOWN INTO OUR
NORTHEASTERN COUNTIES FROM MANITOBA AROUND THE BACKSIDE OF THE
LOW. HRRR HAS CLOUDS CONTINUING OVER THE EASTERN COUNTIES THROUGH
MUCH OF THE NIGHT. THE CLOUDS AND WINDS WILL KEEP AT LEAST THE
EASTERN COUNTIES FROM DROPPING AS COLD AS THEY COULD.
HOWEVER...COLD AIR ADVECTION HAS BEEN STRONG AND SOME LOCATIONS
HAVE ALREADY DROPPED INTO THE 30S WITH DEW POINTS IN THE 20S
OR EVEN TEENS ACROSS PARTS OF THE CWA. THINK THAT THE NORTHWESTERN
TO NORTH CENTRAL COUNTIES WHICH WILL BE THE CLOSEST TO THE HIGH
CENTER AND THUS MORE LIKELY TO SEE WINDS FALL OFF COULD GET DOWN
TO BELOW 32...SO EXPANDED THE FREEZE WARNING A BIT FURTHER EAST.
WINDS AND CLOUDS WILL BE A BIT MORE UNCERTAIN OVER THE VALLEY.
SOME OF THE GUIDANCE HAS TEMPS DOWN BELOW FREEZE CRITERIA WHILE
OTHERS KEEP US ABOVE. DUE TO UNCERTAINTY...WILL JUST GO WITH A
FROST ADVISORY FROM ROSEAU TO THE CENTRAL RED VALLEY INTO
RANSOM/SARGENT.
A FEW LOCATIONS IN THE FAR EASTERN CWA HAVE REPORTED SOME IP THIS
EVENING. HOWEVER...RADAR TRENDS HAVE BEEN DOWNWARD AND NOT MUCH AS
BEEN REPORTED IN THE LAST HOUR OR SO. WILL LET POPS GO AT MIDNIGHT
AS GOING GRIDS SHOW WITH ONLY SOME MINOR ADJUSTMENTS IN THE NEXT
FEW HOURS FOR RADAR TRENDS.
&&
.AVIATION...
CLOUDS HAVE BEEN VFR...AND RAIN SHOWERS HAVE BEEN DISSIPATING
ACROSS THE AREA. NORTH WINDS WILL DECREASE DOWN TO THE 15 KT RANGE
BY MORNING AT KBJI AND KTVF AND BELOW 12 KTS FURTHER WEST.
&&
.PREV DISCUSSION... /ISSUED 336 PM CDT FRI SEP 21 2012/
SHORT TERM...TONIGHT THROUGH MONDAY.
HIGH AMPLITUDE UPPER AIR PATTERN CONTINUES ACROSS THE NORTHERN
PLAINS. PATTERN TEMPERS A BIT BY 84 HOURS AND SHIFTS SLIGHTLY EAST.
ECMWF AND NAM WERE SIMILAR AND SLOW...WHILE THE GEM WAS FAST AND THE
GFS A COMPROMISE. THE ECMWF WAS TRENDING TO THE SOUTH AND WEST OVER
LAST COUPLE RUNS WHILE THE GFS HAD LITTLE CHANGE. WILL USE A
COMBINATION OF THE GFS AND ECMWF. WATER VAPOR LOOP INDICATED
CIRCULATION CENTER SOUTHEAST OF LAKE WINNIPEG AND WAS MOVING SOUTH.
RADAR SHOWED LIGHT SHOWERS MOVING INTO THE NORTHERN MN AND WILL
CONTINUE MOVING SOUTHEAST 35-40 KNOTS THIS EVENING. CANADIAN RADAR
INDICATED POP UP SHOWERS NORTH OF THE FRONT AND SHOULD DISSIPATE
AFTER SUNSET. PRECIPITATION IS FORECAST TO MOVE OUT OF THE AREA BY
LATE EVENING. SO HAVE REMOVED POPS FOR TONIGHT AFTER MIDNIGHT.
TEMPS ARE FORECAST A TAD WARMER IN THE DEVILS LAKE BASIN FOR
TONIGHT. SO WILL CHANGE FREEZE WATCH TO A FREEZE WARNING FOR FAR
NORTHWEST COUNTIES AND A FROST ADVISORY ELSEWHERE IN THE DEVILS LAKE
BASIN. ANOTHER COLD NIGHT FORECAST FOR SAT NIGHT AND LATER SHIFTS
MAY NEED HEADLINES.
WIND ADVISORY IN EFFECT FOR MUCH OF THE AREA FOR TONIGHT EXCEPT THE
WOODS IN THE EASTERN ZONES WITH COLD FRONT MOVING THROUGH. ADIABATIC
LAYER FROM SURFACE TO AROUND 800 HPA WITH 35 TO 40 KNOT POTENTIAL TO
MIX DOWN. EXPECT STRONGEST WINDS TO BE POST FRONTAL AND STRONGEST
WINDS LAST FOR ONE TO THREE HOURS. FRONT AND GUSTY WINDS SHOULD BE
THROUGH AREA BY 03Z.
GOOD SURGE OF COOL AIR TO MOVE IN FROM CANADA TONIGHT AND COOL
WEATHER EXPECTED FOR THE WEEKEND. SOME MODERATION EXPECTED MON
BEFORE ANOTHER SURGE OF COOL AIR MOVES OUT OF CANADA LATE MON.
LONG TERM (MON NIGHT THROUGH FRI)...
MODELS ARE IN DECENT AGREEMENT...WITH THE ECMWF KEEPING US IN MORE
NW FLOW ALOFT...AND THE THE GFS MORE ZONAL AFTER MID WEEK. THE GFS
WOULD MEAN TEMPS WARMING ABOVE NORMAL A BIT FASTER...WITH THE ECMWF
COOLER INITIALLY. THE TREND HAS BEEN MORE TOWARDS THE ECMWF...BUT
EITHER WAY IT WILL REMAIN DRY WITH A SLOW WARMING TREND BY THE END
OF NEXT WEEK.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...FROST ADVISORY FROM 3 AM TO 8 AM CDT SATURDAY FOR NDZ027-029-030-
038-039-049-052.
FREEZE WARNING FROM 3 AM TO 8 AM CDT SATURDAY FOR NDZ006>008-
014>016-024-026-028-054.
MN...FROST ADVISORY FROM 3 AM TO 8 AM CDT SATURDAY FOR MNZ001>005-007-
008-013>015.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
627 PM EDT THU SEP 20 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL PUSH EAST OF THE AREA TONIGHT. LOW PRESSURE
WILL MOVE ACROSS THE CENTRAL LAKES EARLY SATURDAY DRAGGING A STRONG
COLD FRONT ACROSS THE AREA.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AT WHAT POINT DOES ONE GIVE UP BELIEVING THE HRRR. IT HAS CONTINUED
TO SHOW QUITE A BIT OF WEAK CONVECTIVE LOOKING PRECIP SINCE EARLIER
THIS AFTERNOON FOR THE PERIOD 19Z THRU ABOUT 03Z. SO FAR NOTHING
MUCH HAS HAPPENED. RUC WITH CONSIDERABLY LESS PRECIP AND SO FAR
SEEMS TO BE VERIFYING BETTER. WON`T TOTALLY GIVE UP ON PRECIP FOR
THE FIRST HALF OF THE NIGHT BUT HAVE TRIMMED BACK POPS SOME MORE.
MORE CLOUDS HAVE FILLED IN WEST OF THE AREA SO WONDER HOW MUCH
CLEARING WILL BE ABLE TO TAKE PLACE IN THIS AREA. HAVE NOT ADJUSTED
TEMPS YET AS WE AREA CURRENTLY ALREADY GOING 3 TO 5 DEG WARMER THAN
SURROUNDING FORECASTS.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
MODELS STILL NOT IN TOTAL AGREEMENT ON THE TRACK AND TIMING OF THE
NEXT COLD FRONT THAT WILL MOVE ACROSS THE AREA FRIDAY NIGHT INTO
SATURDAY MORNING. NAM STILL THE FASTEST OF THE 3 MODELS. BASICALLY
RAIN WILL DEVELOP FROM THE WEST TOMORROW EVENING AND MOVE ACROSS THE
AREA FRIDAY NIGHT. COULD SEE A FEW LINGERING SHOWERS IN THE EAST
SATURDAY MORNING...BUT MOST OF AREA WILL SEE LULL SATURDAY MORNING.
THEN SECONDARY TROUGH FORECAST TO ROTATE ACROSS THE AREA SATURDAY
AFTERNOON INTO SATURDAY NIGHT. BY 12Z SUNDAY 850 TEMPS DIP TO 0C
SETTING UP POTENTIAL FOR SOME LAKE EFFECT SHOWERS IN THE SNOWBELT
EAST OF CLEVELAND.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE LONG TERM PORTION BEGINS ON MONDAY WITH THE GFS AND ECMWF
SIMILAR. BOTH SHOW HIGH SURFACE PRESSURE ACROSS THE TENNESSEE AND
LOWER OHIO VALLEY AND AN UPPER LOW OVER HUDSON BAY. 850MB TEMPS
ACROSS THE AREA ALSO SIMILAR AT 2 TO 4C. GFS HOWEVER SHOWS DRY AIR
ACROSS THE AREA WHILE THE ECMWF IS A BIT MORE MOIST WITH MORE OF A
NORTHWEST FLOW ALOFT. GIVEN THE DIFFERENCE WILL SIDE WITH THE NEWER
GFS. WILL HAVE A SLIGHT CHANCE OF A SHOWER IN THE SNOW BELT
COUNTIES BUT WITH THE DRY AIR IN PLACE...NOT LOOKING FOR MUCH.
TUESDAY MODELS COME MORE INTO PHASE WITH THE UPPER TROF NOW
EXTENDING AVER THE GREAT LAKES AND THE SURFACE HIGH NOW MOVING OFF
THE MID ATLANTIC COAST. THE GFS HOWEVER SHOWS AN EMBEDDED SHORT WAVE
WITH ASSOCIATED MOISTURE MOVING ACROSS THE AREA DURING THE DAY WHILE
THE ECMWF DOES NOT SHOW THIS. WILL SIDE MORE TOWARD THE DRIER ECMWF
GIVEN EVERYTHING ELSE IS FAIRLY CLOSE. THE MODELS DO SHOW WARMER AIR
MOVING INTO THE AREA WHICH WOULD FAVOR MORE OF A PARTLY SUNNY DAY VS
CLOUDS. WEDNESDAY A SHORT WAVE RIDGE WILL BE MOVING ACROSS WESTERN
ONTARIO KICKING THE UPPER TROF FURTHER EAST ACROSS THE GREAT LAKES.
MODELS START TO DIFFER AGAIN WITH THE GFS TAKING A COLD FRONT SOUTH
ACROSS THE REGION WHILE THE ECMWF IS MUCH SLOWER. WILL SIDE HERE
WITH THE GFS AGAIN AND BRING THE FRONT THROUGH GIVEN THE SIZE AND
POSITION OF THE SURFACE HIGH TO OUR NORTH.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
MIDDLE AND HIGH LEVEL CLOUDS NOW COVERING MOST OF THE FORECAST
AREA. SOME SCATTERED SHOWERS AND A FEW EMBEDDED THUNDERSTORMS HAVE
BEEN ASSOCIATED WITH THIS WEAK FRONTAL SYSTEM MOVING EASTWARD
ACROSS WESTERN OHIO AND SOUTHERN CANADA.
THESE SHOWERS WILL ATTEMPT TO MOVE EASTWARD BUT DEWPOINTS REMAIN
REMAIN IN THE 40S AT SEVERAL SITES IN CENTRAL AND EASTERN OHIO.
WILL MENTION A FEW SHOWERS AND USE VCSH AT A COUPLE SITES.
SOUTHWEST WINDS 10 TO 15 KNOTS WITH GUSTS TO 20 TO 25 THIS
AFTERNOON THEN DIMINISHING BEHIND THE WEAK FRONTAL SYSTEM.
.OUTLOOK...AREAS OF NON VFR IN SHOWERS FRI AFTERNOON THROUGH
SATURDAY NIGHT.
&&
.MARINE...
LAKE REMAINS CHOPPY WITH A SSW FLOW. HAVE ALLOWED THE WEST END SMALL
CRAFT TO EXPIRE WITH SUSTAINED WIND SPEEDS UNDER 22 KNOTS. THINK THE
2 TO 4 FEET WILL HOLD ACROSS THE EAST END AS WE ARE EXPECTING A
SUBTLE WIND SHIFT THIS EVENING BUT WINDS RELAXING SOME. IN GENERAL
SOUTHWEST FLOW CONTINUES WITH UPPER TROUGH/CYCLONIC FLOW ACROSS THE
NORTHERN AND CENTRAL LAKES FROM FRIDAY INTO SATURDAY. BETWEEN THOSE
TWO DAYS THERE WILL BE SLIGHT FLUCTUATIONS IN THE WIND DIRECTION WITH
WEAK DISTURBANCES MOVING ACROSS. BY SATURDAY NIGHT THE UPPER TROUGH
SWINGS ACROSS THE EASTERN LAKES AND THE WEST-NORTHWEST FLOW
INCREASES. IT IS UNCERTAIN HOW STRONG WINDS MAY BE WITH ONE MODEL
HINTING AT GALES AND ANOTHER MUCH LESS. FOR NOW WILL STICK AT 20-25
KNOTS. SMALL CRAFT ADVISORY POSSIBLE SATURDAY AND LIKELY SUNDAY. IT
WILL NOT TAKE MUCH TO KICK UP THE LAKE THIS TIME OF YEAR. HIGH
PRESSURE BUILDS ACROSS THE LAKE EARLY NEXT WEEK.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...DJB
NEAR TERM...DJB/ADAMS
SHORT TERM...DJB
LONG TERM...TK
AVIATION...BC
MARINE...OUDEMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
950 AM EDT THU SEP 20 2012
.SYNOPSIS...
A WEAK COLD FRONT WILL MOVE INTO THE REGION AND DISSIPATE BY THIS
EVENING. A SERIES OF LOW PRESSURE SYSTEMS WILL THEN MOVE THROUGH
THE REGION FROM FRIDAY THROUGH SATURDAY. THESE WEATHER SYSTEMS
WILL PROVIDE A CHANCE OF RAIN FOR THE REGION. MUCH COOLER AIR WILL
MOVE IN BEHIND A COLD FRONT FOR SUNDAY AND EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SHOWERS AND ISOLATED THUNDERSTORMS HAVE BEEN PROGRESSING AHEAD OF
A WEAK COLD FRONT. CONVECTION HAS BEEN WEAKENING AS IT MOVES
ACROSS CENTRAL INDIANA BUT HELD TOGETHER FURTHER NORTH. APPEARS
THAT WEAKENING TREND WILL CONTINUE FURTHER EAST INTO THE FORECAST
AREA. BEST CHANCE OF RAIN WILL BE IN THE FAR NORTHWEST COUNTIES.
PAST FEW HRRR RUNS SUGGEST THAT SOME PRECIPITATION COULD MAKE IT
INTO CENTRAL OHIO. SO MAINTAINED SLIGHT CHANCE POPS GENERALLY
NORTH OF I-70 ALTHOUGH ANY RAIN MAY END UP BEING JUST TRACE
AMOUNTS. FORECAST TEMPERATURES LOOK REASONABLE AT THIS POINT WITH
ONLY MINOR ADJUSTMENTS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
THERE IS INCREASING MODEL CONFIDENCE IN THE GENERAL EVOLUTION OF A
TWO-PART WEATHER SYSTEM FOR FRIDAY AND SATURDAY...FORCING THE
INTRODUCTION OF LIKELY POPS INTO THE GRIDS.
A LARGE UPPER LEVEL TROUGH WILL CONTINUE TO DEEPEN OVER THE GREAT
LAKES REGION...WITH RELATIVELY QUICK MID AND UPPER LEVEL FLOW (WSW
TO ENE) ACROSS THE OHIO VALLEY. AN INITIAL WAVE IN THE FLOW IS
EXPECTED TO BRING THE HIGHEST CHANCES FOR PRECIPITATION TO THE
REGION...ESPECIALLY FOR SE INDIANA...THE MIAMI VALLEY...AND
CENTRAL OHIO. LOCATIONS FURTHER SOUTH MAY NOT BE IMPACTED BY THE
AXIS OF THE HIGHEST RAINFALL AMOUNTS. THERE IS ENOUGH AGREEMENT
IN TIMING THIS FEATURE TO INCLUDE LIKELY POPS IN THESE AREAS...BUT
STILL A BIT TOO MUCH UNCERTAINTY TO USE AN 80 PERCENT CHANCE OR
HIGHER. THE NAM12 REMAINS A RATHER QUICK OUTLIER...THOUGH THE GFS
IS ALSO FASTER THAN THE ECMWF/CMC. UP TO AN INCH OF RAIN IS
EXPECTED.
FORECAST AGREEMENT HAS ALSO IMPROVED SOMEWHAT WITH A SECOND (AND
MUCH STRONGER) DISTURBANCE THAT MOVES VERY QUICKLY SOUTHEAST FROM
MINNESOTA ON SATURDAY. DEPICTED AS A TIGHT MID-LEVEL CLOSED
LOW...WITH A TRAILING COLD FRONT...THE COLD/DRY ADVECTION TO THE
SOUTH OF THE LOW TRACK WILL BE PRONOUNCED. THERE WILL BE A DEFINED
BREAK IN BETWEEN THE TWO WEATHER SYSTEMS...AND PRECIPITATION WITH
THE SATURDAY SYSTEM IS EXPECTED TO PRIMARILY REMAIN NORTH OF THE
CWA. THE NORTHERN COUPLE OF TIERS OF COUNTIES WILL PROBABLY BE
IMPACTED BY CONVECTIVELY-INDUCED SHOWERS. AS THE DEEP TROUGH
REMAINS NEAR THE AREA (THOUGH ITS AXIS WILL BE TO THE NE)...A
SIMILAR (THOUGH LESS PRONOUNCED) SITUATION WILL BE POSSIBLE ON
SUNDAY...WITH QUITE A BIT OF DIURNAL CLOUD COVER AND A SLIGHT
CHANCE OF SOME LIGHT SHOWERS IN CENTRAL OHIO.
THE TEMPERATURE FORECAST IS SOMEWHAT CHALLENGING...GIVEN THE
OCCASIONAL LOW PRESSURE SYSTEMS AND PRECIPITATION
CHANCES...FOLLOWED BY AN IMPRESSIVE MASS OF COOL AIR. THE COLD
POOL ALOFT (BY SUNDAY AND SUNDAY NIGHT) WILL BE UP TO TWO STANDARD
DEVIATIONS BELOW CLIMO...AND WITH THE SURFACE HIGH IN PLACE ON
SUNDAY NIGHT...THE LOWS MONDAY MORNING WILL BE COLD. AS HAS BEEN
THE TREND FOR THE PAST FEW SHIFTS...TEMPS ON SUNDAY AND MONDAY
HAVE BEEN DECREASED ANOTHER DEGREE OR TWO...WITH POTENTIALLY
FROST-INDUCING TEMPS IN THE GRIDS FOR SUNDAY NIGHT / MONDAY
MORNING.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
A GRADUAL WARMUP OF 4-5 DEGREES WILL OCCUR EACH DAY AFTER SUNDAY
AND SUNDAY NIGHT UNDER PARTLY CLOUDY SKIES...REACHING BACK TO
CLIMATOLOGICAL NORMS IN THE LOW 70S ON TUESDAY AND SURPASSING THEM
WITH MID TO UPPER 70S ON WEDNESDAY.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
FOR TODAY...THE WEAK COLD FRONT WILL SLOWLY PUSH EAST INTO THE
REGION. THE FRONT IS MOISTURE STARVED AND MAINLY MID LEVEL CLOUDS
WILL MOVE IN ADVANCE OF IT. ANY LIGHT SHOWERS OR SPRINKLES SHOULD
REMAIN NORTH AND WEST OF THE TAF SITES. AN INCREASING PRESSURE
GRADIENT AND DAY TIME MIXING WILL ALLOW WINDS TO INCREASE FROM THE
SOUTH SOUTHWEST AROUND 15 KNOTS WITH GUSTS BETWEEN 20 TO 25 KNOTS
BY LATE MORNING.
FOR TONIGHT...THE COLD FRONT WILL EVENTUALLY WASH OUT OVER THE AREA.
A MIX OF MID AND HIGH LEVEL CLOUDS CAN BE EXPECTED ALONG WITH
DIMINISHING WINDS.
LOW PRESSURE IS FORECAST TO MOVE FROM THE CENTRAL PLAINS TO THE
OHIO VALLEY ON FRIDAY. THIS SYSTEM WILL BRING THE NEXT CHANCE OF
SHOWERS...POSSIBLY A THUNDERSTORM...FROM LATE FRIDAY AFTERNOON
INTO FRIDAY NIGHT.
.OUTLOOK...MVFR CEILINGS AND VISIBILITIES POSSIBLE LATE FRIDAY
AFTERNOON INTO SATURDAY MORNING. WEST TO NORTHWEST WIND GUSTS
UP TO 30 KNOTS POSSIBLE SATURDAY AFTERNOON AND EVENING IN
ASSOCIATION WITH A COLD FRONT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...HATZOS
LONG TERM...FRANKS
AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
740 AM EDT THU SEP 20 2012
.SYNOPSIS...
A DEEPENING UPPER TROUGH OVR THE GRT LKS WILL PUSH A COLD FRONT
THROUGH CENTRAL PA LATE SATURDAY. THE UPPER TROUGH WILL ROTATE
THROUGH THE REGION SUNDAY...FOLLOWED BY HIGH PRESSURE EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY AM MODIS 11-3.7UM IMAGERY SHOWING DENDRITIC PATTERN OF FOG
IN THE VALLEYS...THE RESULT OF A COOL...CALM MORNING AND RELATIVELY
WARM RIVER/STREAM WATERS. LATEST 3KM HRRR SFC RH FIELDS SUGGEST
THE MOST PERSISTENT FOG WILL BE UNDER SFC RIDGE AXIS ACROSS THE
SUSQ VALLEY...WHERE PATCHES COULD LINGER UNTIL 14Z-15Z.
LG SCALE SUBSIDENCE AND DRY AIR ASSOCIATED WITH HIGH PRESSURE SYSTEM
WILL PROVIDE THE AREA WITH ABUNDANT SUNSHINE LATER TODAY. GEFS 8H
TEMPS SHOW MODERATION OF THIS ONCE CHILLY AIR MASS WITH MEAN 8H
TEMPS NR 9C BY AFTN...SUPPORTIVE OF HIGHS IN THE U60S AND L70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
DYING COLD FRONT...CURRENTLY OVR MICHIGAN...WILL PUSH INTO WESTERN
PA TONIGHT...ACCOMPANIED BY AN INCREASE IN CLOUDS...BUT LITTLE IF
ANY PRECIP. WILL RAMP UP POPS TO ARND 15 PCT OVERNIGHT ACROSS THE
W MTNS WITH ARRIVAL OF THIS WEAK FRONT. HOWEVER...NEARLY ALL THE LG
SCALE FORCING REMAINS WEST OF PA ASSOC WITH DEEPENING UPPER TROUGH...SO
THE CHANCE OF ANY -SHRA WILL BE MINIMAL. SOUTHERLY FLOW AHEAD OF
THIS BOUNDARY WILL DRAW HIGHER HUMIDITY BACK INTO THE REGION...RESULTING
IN A MUCH MILDER NIGHT...WITH MINS MOSTLY ARND 50F.
DYING COLD FRONT WILL WASH OUT OVR CENTRAL PA ON FRIDAY...PROVIDING
THE FOCUS FOR SCT AFTN -SHRA. WILL PLACE AXIS OF HIGHEST POPS
/ARND 30 PCT/ ACROSS THE CENTRAL COUNTIES...WHERE MDL DATA SHOWS
TONGUE OF HIGHER SFC-8H THTE.
DESPITE A PT-MOCLDY SKY...TEMPS SHOULD REACH NR SEASONAL NORMS
FRI AFTN DUE TO WARMER RETURN SOUTHERLY FLOW AS SFC RIDGE PASSES
OFF THE COAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
LITTLE SPREAD AMONG MED RANGE GUIDANCE WITH RESPECT TO THE LG
SCALE PATTERN OVR THE NORTHEAST CONUS THIS WEEKEND. ALL GUIDANCE
INDICATING UPPER LOW OVR ONTARIO GRADUALLY SHIFTS EAST...PUSHING A
COLD FRONT THRU CENTRAL PA LATER SAT OR SAT NIGHT. AS MDL DATA HAS
COME INTO LINE W/REGARDS TO TIMING OF FRONT...HAVE BUMPED POPS UP
TO LIKELY FOR SAT PM. MDL DATA HINTING THAT ENOUGH HEATING/DESTABILIZATION
WILL OCCUR AHEAD OF FROPA FOR MENTION OF THUNDER IN ADDITION TO
THE SHOWERS. SOME UNCERTAINTY W/REGARDS TO AMT OF PRE-FRONTAL
CLOUD COVER AND RESULTING CAPES. HOWEVER...STRONG DEEP LYR
SHEAR...COMBINED WITH EVEN MARGINAL INSTABILITY...COULD POSE THE
THREAT OF SVR WX OVR ROUGHLY THE EASTERN HALF OF THE STATE SAT
AFTN.
AS THE UPPER TROF AXIS CROSSES THE REGION ON SUNDAY...ADDITIONAL
SHOWERS ARE POSSIBLE ACROSS MAINLY WESTERN AND NORTHERN SECTIONS.
A RATHER TIGHT PRES GRADIENT WILL PRODUCE GUSTY W WIND ACROSS THE
REGION...ACCENTUATING THE POST-FRONT CHILL. GEFS MEAN 8H TEMPS
SUPPORT HIGHS FROM THE M50S NW MTNS TO THE U60S SE.
FAIR BUT STILL COOL WEATHER APPEAR LIKELY EARLY NEXT WEEK AS
UPPER TROUGH BEGINS TO LIFT OUT AND SFC HIGH PRES BUILDS EAST
ACROSS THE OHIO VALLEY. GEFS AND ECMWF MEAN 8H TEMPS REMAIN BLW
SEASONAL NORMS BOTH MON AND TUE. SFC HIGH PRES SYS WILL PASS OFF THE
MID ATLANTIC COAST BY MID WEEK...ALLOWING A MILDER SW FLOW TO
DEVELOP.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE WILL REMAIN SITUATED OVER THE REGION THROUGH TONIGHT.
VALLEY FOG EARLY ON THIS CHILLY MORNING CONFINED MAINLY NORTH OF
INTERSTATE 80 /IMPACTING KUNV-KIPT-KSEG. THE FOG WILL DISSIPATE
QUICKLY AFTER 12-13Z - BRINGING A VFR DAY FOR ALL OF CENTRAL PA
WITH ONLY SOME MID/HIGH CLOUDS STREAMING OVERHEAD. SURFACE WINDS
WILL PICK UP FROM THE SOUTH...INCREASING TO 10 MPH WITH GUSTS
APPROACHING 20 MPH MAINLY ACROSS THE WESTERN HIGHER TERRAIN.
TONIGHT...WINDS BECOME LIGHT AGAIN. MID CLOUD DECK WILL THICKEN A
BIT ACROSS THE WEST...BUT VFR WILL AGAIN PREVAIL EXCEPT FOR SOME
VALLEY FOG AGAIN TOWARD SUNRISE FRI.
OUTLOOK...
FRI...MAINLY VFR. ISOLATED SHOWERS COULD PRODUCE LOCAL MVFR
CONDITIONS.
SAT...MAINLY VFR BUT A PERIOD OF MVFR CONDITIONS POSSIBLE
IN LIKELY SHOWERS.
SUN...MAINLY VFR BUT MVFR CONDITIONS POSSIBLE ACROSS THE
HIGHER MTNS.
MON...VFR...AS HIGH BUILDS ACROSS THE REGION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ005-006-010-
011.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
558 AM EDT THU SEP 20 2012
.SYNOPSIS...
A DEEPENING UPPER TROUGH OVR THE GRT LKS WILL PUSH A COLD FRONT
THROUGH CENTRAL PA LATE SATURDAY. THE UPPER TROUGH WILL ROTATE
THROUGH THE REGION SUNDAY...FOLLOWED BY HIGH PRESSURE EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY AM MODIS 11-3.7UM IMAGERY SHOWING DENDRITIC PATTERN OF FOG
IN THE VALLEYS...THE RESULT OF A COOL...CALM MORNING AND RELATIVELY
WARM RIVER/STREAM WATERS. LATEST 3KM HRRR SFC RH FIELDS SUGGEST
THE MOST PERSISTENT FOG WILL BE UNDER SFC RIDGE AXIS ACROSS THE
SUSQ VALLEY...WHERE PATCHES COULD LINGER UNTIL 14Z-15Z.
LG SCALE SUBSIDENCE AND DRY AIR ASSOCIATED WITH HIGH PRESSURE SYSTEM
WILL PROVIDE THE AREA WITH ABUNDANT SUNSHINE LATER TODAY. GEFS 8H
TEMPS SHOW MODERATION OF THIS ONCE CHILLY AIR MASS WITH MEAN 8H
TEMPS NR 9C BY AFTN...SUPPORTIVE OF HIGHS IN THE U60S AND L70S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
DYING COLD FRONT...CURRENTLY OVR MICHIGAN...WILL PUSH INTO WESTERN
PA TONIGHT...ACCOMPANIED BY AN INCREASE IN CLOUDS...BUT LITTLE IF
ANY PRECIP. WILL RAMP UP POPS TO ARND 15 PCT OVERNIGHT ACROSS THE
W MTNS WITH ARRIVAL OF THIS WEAK FRONT. HOWEVER...NEARLY ALL THE LG
SCALE FORCING REMAINS WEST OF PA ASSOC WITH DEEPENING UPPER TROUGH...SO
THE CHANCE OF ANY -SHRA WILL BE MINIMAL. SOUTHERLY FLOW AHEAD OF
THIS BOUNDARY WILL DRAW HIGHER HUMIDITY BACK INTO THE REGION...RESULTING
IN A MUCH MILDER NIGHT...WITH MINS MOSTLY ARND 50F.
DYING COLD FRONT WILL WASH OUT OVR CENTRAL PA ON FRIDAY...PROVIDING
THE FOCUS FOR SCT AFTN -SHRA. WILL PLACE AXIS OF HIGHEST POPS
/ARND 30 PCT/ ACROSS THE CENTRAL COUNTIES...WHERE MDL DATA SHOWS
TONGUE OF HIGHER SFC-8H THTE.
DESPITE A PT-MOCLDY SKY...TEMPS SHOULD REACH NR SEASONAL NORMS
FRI AFTN DUE TO WARMER RETURN SOUTHERLY FLOW AS SFC RIDGE PASSES
OFF THE COAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
LITTLE SPREAD AMONG MED RANGE GUIDANCE WITH RESPECT TO THE LG
SCALE PATTERN OVR THE NORTHEAST CONUS THIS WEEKEND. ALL GUIDANCE
INDICATING UPPER LOW OVR ONTARIO GRADUALLY SHIFTS EAST...PUSHING A
COLD FRONT THRU CENTRAL PA LATER SAT OR SAT NIGHT. AS MDL DATA HAS
COME INTO LINE W/REGARDS TO TIMING OF FRONT...HAVE BUMPED POPS UP
TO LIKELY FOR SAT PM. MDL DATA HINTING THAT ENOUGH HEATING/DESTABILIZATION
WILL OCCUR AHEAD OF FROPA FOR MENTION OF THUNDER IN ADDITION TO
THE SHOWERS. SOME UNCERTAINTY W/REGARDS TO AMT OF PRE-FRONTAL
CLOUD COVER AND RESULTING CAPES. HOWEVER...STRONG DEEP LYR
SHEAR...COMBINED WITH EVEN MARGINAL INSTABILITY...COULD POSE THE
THREAT OF SVR WX OVR ROUGHLY THE EASTERN HALF OF THE STATE SAT
AFTN.
AS THE UPPER TROF AXIS CROSSES THE REGION ON SUNDAY...ADDITIONAL
SHOWERS ARE POSSIBLE ACROSS MAINLY WESTERN AND NORTHERN SECTIONS.
A RATHER TIGHT PRES GRADIENT WILL PRODUCE GUSTY W WIND ACROSS THE
REGION...ACCENTUATING THE POST-FRONT CHILL. GEFS MEAN 8H TEMPS
SUPPORT HIGHS FROM THE M50S NW MTNS TO THE U60S SE.
FAIR BUT STILL COOL WEATHER APPEAR LIKELY EARLY NEXT WEEK AS
UPPER TROUGH BEGINS TO LIFT OUT AND SFC HIGH PRES BUILDS EAST
ACROSS THE OHIO VALLEY. GEFS AND ECMWF MEAN 8H TEMPS REMAIN BLW
SEASONAL NORMS BOTH MON AND TUE. SFC HIGH PRES SYS WILL PASS OFF THE
MID ATLANTIC COAST BY MID WEEK...ALLOWING A MILDER SW FLOW TO
DEVELOP.
&&
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE WILL REMAIN SITUATED OVER THE REGION LATE THIS WEEK.
EXPECT VFR CONDITIONS OVERNIGHT FOR THE MAJORITY OF LOCATIONS...
WITH SOME VALLEY FOG IMPACTING KIPT-KSEG WITH MVFR/IFR CONDITIONS
THROUGH SUNRISE. DID NOT MENTION FOR KBFD AS WIND GRADIENT PICKS
UP A LITTLE HEADING TOWARD SUNRISE.
DURING THE DAY THU...VFR CONDITIONS WILL PREVAIL WITH ONLY SOME
MID/HIGH CLOUDS STREAMING OVERHEAD. SURFACE WINDS DO PICK UP FROM
THE SOUTH...INCREASING TO 10 MPH WITH GUSTS APPROACHING 20 MPH.
OUTLOOK...
FRI...MAINLY VFR. ISOLATED SHOWERS COULD PRODUCE LOCAL MVFR
CONDITIONS.
SAT...MAINLY VFR BUT A PERIOD OF MVFR CONDITIONS POSSIBLE
IN LIKELY SHOWERS.
SUN...MAINLY VFR BUT MVFR CONDITIONS POSSIBLE ACROSS THE
HIGHER MTNS.
MON...VFR...AS HIGH BUILDS ACROSS THE REGION.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR PAZ005-006-010-
011.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS AMARILLO TX
344 PM CDT THU SEP 20 2012
.DISCUSSION...
A STRONG UPPER LOW OVER HUDSON BAY ALONG WITH AN AMPLIFIED RIDGE
ACROSS THE WESTERN CONUS IS MAINTAINING NORTHWEST FLOW ALOFT ACROSS
THE PANHANDLES. A SUBTLE SHORTWAVE TROUGH WILL MOVE OUT OF THE
ROCKIES AND ACROSS THE TEXAS PANHANDLE TONIGHT. A DRY AIR MASS
REMAINS ACROSS THE AREA WITH DEWPOINTS ONLY IN THE UPPER 30S TO THE
MID 40S. HOWEVER DESPITE THIS LACK OF SUBSTANTIAL MOISTURE...HAVE
LEFT IN MENTION OF ISOLATED THUNDERSTORMS IN THE EASTERN TEXAS
PANHANDLE WHERE LIFT FROM THIS SHORTWAVE CAN INTERACT WITH SLIGHTLY
HIGHER MOISTURE VALUES. SPC RUC MESOSCALE ANALYSIS SHOWS SOME
INSTABILITY IN THIS AREA WITH SBCAPES AROUND 1500 J/KG. HOWEVER A
FAIRLY STRONG CAP ALSO EXISTS IN THIS AREA SO THUNDER DEVELOPMENT
LOOKS PRETTY SLIM. LOWS TONIGHT WILL BE SLIGHTLY WARMER WITH LOWS
RANGING FROM THE UPPER 40S IN THE WESTERN OKLAHOMA PANHANDLE TO
NEAR 60 DEGREES IN THE SOUTHEAST TEXAS PANHANDLE.
A COLD FRONT WILL PUSH SOUTH ACROSS THE PANHANDLES FRIDAY. CAN SEE A
PERIOD OF GUSTY WINDS INITIALLY BEHIND THE FRONT ALTHOUGH WINDS
WILL DIMINISH DURING THE DAY AS SURFACE HIGH PRESSURE BUILDS ACROSS
THE CENTRAL PLAINS. GIVEN THE NORTHERLY FETCH...HAVE LEANED TOWARD
THE COOLER MAV GUIDANCE WITH HIGH TEMPS IN THE 80S TO THE LOWER 90S
IN THE FAR SOUTHEAST TEXAS PANHANDLE.
THE WESTERN CONUS UPPER RIDGE WILL SLIDE TO THE EAST OVER THE
WEEKEND WHERE IT WILL FLATTEN EARLY NEXT WEEK IN RESPONSE TO AN
UPPER LOW MOVING ACROSS THE GREAT BASIN. ALTHOUGH THE FIRST DAY OF
FALL IS SATURDAY...TEMPERATURES WILL BE MORE SUMMER-LIKE OVER THE
WEEKEND AND EARLY NEXT WEEK DUE TO SOUTHERLY WINDS AND RISING
HEIGHTS. MEDIUM RANGE MODELS ARE COMING INTO BETTER AGREEMENT WITH
THE UPPER LOW AS IT MOVES ACROSS THE CENTRAL PLAINS MID WEEK. THE
FLOW ALOFT WILL TRANSITION TO THE SOUTHWEST ALLOWING FOR THE
TRANSPORT OF MOISTURE ACROSS THE AREA. THIS LOW CAN TAP INTO THIS
MOISTURE AND BRING THE NEXT CHANCE OF RAIN TO THE AREA BY AROUND
THURSDAY. HOWEVER SINCE THIS IS STILL QUITE AWAYS OFF INTO THE
FUTURE HAVE OPTED TO KEEP THE INHERITED DRY FORECAST INTACT.
CLK
&&
.FIRE WEATHER...
AFTERNOON RELATIVE HUMIDITY VALUES CAN DROP TO AROUND 20 PERCENT
ACROSS THE OKLAHOMA PANHANDLE AND THE NORTHERN TEXAS PANHANDLE
FRIDAY. HOWEVER 20 FOOT WINDS ARE EXPECTED TO STAY BELOW 15
MPH...PRECLUDING ELEVATED AND CRITICAL FIRE WEATHER CONDITIONS. A
WIND SHIFT TO THE NORTH WILL OCCUR FRIDAY AS A COLD FRONT
DROPS SOUTH ACROSS THE AREA. GUSTY WINDS CAN ALSO DEVELOP
BEHIND THIS FRONT BUT WILL DIMINISH LATER IN THE DAY. SLIGHTLY COOLER
AIR BEHIND THIS FRONT WILL SPREAD ACROSS THE AREA SATURDAY WHICH WILL
LEAD TO MINIMUM RELATIVE HUMIDITIES TO STAY ABOVE 20 PERCENT.
UNSEASONABLY WARM TEMPERATURES WILL RESULT IN RELATIVE HUMIDITY
VALUES TO FALL TO AROUND 15 TO 20 PERCENT IN THE WESTERN OKLAHOMA
PANHANDLE AND THE NORTHWEST TEXAS PANHANDLE SUNDAY AND MONDAY.
HOWEVER 20 FOOT WINDS ARE EXPECTED TO BE BELOW 15 MPH...PRECLUDING
ELEVATED AND CRITICAL FIRE WEATHER CONDITIONS. RELATIVE HUMIDITIES
SHOULD STAY NEAR OR ABOVE 20 PERCENT AFTER MONDAY AND WHILE 20 FOOT
WINDS FOR THE MOST PART WILL STAY BELOW 15 MPH...THEY CAN INCREASE TO
AROUND 15 TO 20 PERCENT AT TIMES. HOWEVER THE STRONGER WINDS ARE
EXPECTED TO OCCUR WHERE RELATIVE HUMIDITY VALUES WILL BE ABOVE
CRITICAL THRESHOLDS. THE CHANCE FOR WETTING RAINS IS SLIM THROUGH THE
NEXT SEVEN DAYS.
CLK
&&
.PRELIMINARY POINT TEMPS/POPS...
AMARILLO TX 58 84 55 84 54 / 5 0 0 5 5
BEAVER OK 54 88 54 83 50 / 5 0 5 5 10
BOISE CITY OK 50 84 49 83 52 / 0 5 5 10 5
BORGER TX 60 88 60 87 57 / 5 0 0 5 10
BOYS RANCH TX 51 86 53 88 53 / 0 0 0 5 5
CANYON TX 55 85 54 84 51 / 5 0 0 5 5
CLARENDON TX 60 87 58 86 56 / 10 5 0 5 10
DALHART TX 50 84 52 83 49 / 0 0 0 10 5
GUYMON OK 54 87 53 84 50 / 5 0 5 5 10
HEREFORD TX 52 85 53 85 51 / 5 5 0 5 5
LIPSCOMB TX 56 87 53 85 50 / 10 5 5 5 10
PAMPA TX 58 84 56 83 53 / 10 5 0 5 10
SHAMROCK TX 59 89 57 86 53 / 10 5 0 5 10
WELLINGTON TX 59 93 58 90 54 / 10 5 0 5 10
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
OK...NONE.
&&
$$
09/05
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
620 AM CDT THU SEP 20 2012
.AVIATION...
ONLY CONCERN THIS MORNING IS THE IFR STRATUS EXPANDING SLOWLY OVER
THE TX HILL COUNTRY AND WHETHER IT WILL WACO BEFORE 15Z. LOOK AT
KGRK VWP AND LEDBETTER PROFILER SHOW VEERED WSW FLOW 10-15 KTS IN
THE LOWEST 1-2 KFT. FEELING IS THE BULK OF STRATUS WILL REMAIN
SOUTH OF WACO...DESPITE RUC OPS40 AND GFS BUFR SOUNDINGS INDICATING
A BRIEF POTENTIAL BETWEEN 13-14Z. PER COORD WITH CWSU AND VEERED
LOW LEVEL FLOW...WILL ONLY INTRODUCE SCT009 AT WACO AND MONITOR
CLOSELY THE NEXT SEVERAL HOURS.
OTHERWISE...ALL N TX AIRPORTS WILL BE VFR THROUGH 30 HRS WITH
SCATTERED CIRRUS EXPECTED WITH NW FLOW OVERHEAD. BOUNDARY LAYER
APPEARS TOO DRY AND MIXED BY 12Z FRI FOR ANY STRATUS CONCERNS.
SOUTH FLOW AROUND 10 KTS IS EXPECTED THROUGH TONIGHT.
05/
&&
.PREV DISCUSSION... /ISSUED 305 AM CDT THU SEP 20 2012/
UPPER RIDGE AXIS REMAINS OVER THE GREAT BASIN THIS MORNING. IT
WILL SLOWLY MOVE EAST AND WEAKEN AS AN UPPER LOW MOVES INTO THE
WESTERN U.S. FROM THE PACIFIC. CANADIAN AIR IS BEING PULLED SOUTH
ACROSS THE CENTRAL PLAINS ALONG THE BACK SIDE OF THE RIDGE...BUT
BY THE TIME IT GETS THIS FAR SOUTH IT WILL BE HIGHLY MODIFIED.
I SEE NO MAJOR CHANGES TO OUR FORECAST THROUGH SATURDAY. THE
SUNDAY COLD FRONT NOW LOOKS WEAKER. THE GFS ACTUALLY STALLS THE
FRONT NEAR THE RED RIVER BUT IT IS AN OUTLIER SO HAVE GONE WITH
ECMWF/GEM/CMC SOLUTION WHICH BRINGS THE FRONT THROUGH OUR AREA
BUT IT IS WEAKER THAN PREVIOUS FORECASTS. I HAVE RAISED SUNDAY
HIGHS A BIT MORE SINCE THE FRONT IS SO WEAK...AND IF THE GFS IS
ACTUALLY CORRECT SUNDAY COULD SEE HIGHS IN THE 90S. THE REST OF
THE FORECAST WEEK LOOKS DRY AND WARM. 84
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 93 66 95 66 90 / 0 0 5 5 10
WACO, TX 91 62 92 63 92 / 0 0 5 5 10
PARIS, TX 90 59 93 62 92 / 0 0 5 5 10
DENTON, TX 94 64 94 63 89 / 0 0 5 5 10
MCKINNEY, TX 93 61 95 61 92 / 0 0 5 5 10
DALLAS, TX 93 66 95 67 91 / 0 0 5 5 10
TERRELL, TX 92 61 93 63 91 / 0 0 5 5 10
CORSICANA, TX 91 62 92 64 93 / 0 0 5 5 10
TEMPLE, TX 91 61 91 62 92 / 0 0 5 5 10
MINERAL WELLS, TX 93 60 93 61 89 / 0 0 5 5 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
05/84
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
922 PM CDT FRI SEP 21 2012
.SHORT TERM...TONIGHT INTO SATURDAY MORNING
922 PM CDT FRI SEP 21 2012
THE MAIN SHORT TERM UPDATES TO THE FORECAST WERE WITH BEEFING UP
THE WIND SPEEDS AND ADJUSTING THE PRECIPITATION CHANCES FOR
OVERNIGHT AS THE COLD FRONT QUICKLY MOVES THROUGH AND THE POTENT
MID LEVEL TROUGH SWINGS DOWN.
WINDS ACROSS MUCH OF NORTHERN MINNESOTA HAVE JUMPED UP TO HAVING
SUSTAINED WINDS OF 20-30MPH WITH GUSTS UP TO 40MPH AT
TIMES...PARTICULARLY UNDER THE STRONGEST COLD PUSH WHICH IS
DROPPING STRAIGHT SOUTH ACROSS MINNESOTA. THIS TIGHT PRESSURE
GRADIENT MOVES INTO THE REGION OVERNIGHT BEHIND THE FRONT...SO
HAVE NO REASON TO THINK THAT THESE HIGH GUSTS WILL NOT CARRY INTO
THE REGION POST-FROPA.
PRECIPITATION-WISE...THERE WILL BE TWO MAIN WAVES THAT WILL
PRODUCE SHOWERS FOR THE REGION WITH ONE COMING THROUGH WITH THE
COLD FRONT AND THE SECOND...MORE WIDESPREAD BATCH COMING WITH THE
CORE OF THE MID LEVEL TROUGH. THERE STILL DOES APPEAR TO BE A
TINY WINDOW OF OPPORTUNITY FOR THE LOW LEVELS TO BE COOL ENOUGH
FOR SOME SNOW SHOWERS TO OCCUR ACROSS CENTRAL WISCONSIN WHERE THE
CORE OF THE MID LEVEL LOW DROPS THROUGH. 21.23Z RAP FORECAST
SOUNDINGS FROM ACROSS WESTERN WISCONSIN MIMIC THAT OF THE 22.00Z
INTERNATIONAL FALLS SOUNDING ALONG WITH OTHER LAPS SOUNDINGS FROM
PORTIONS OF SOUTHWEST ONTARIO THAT HAVE REPORTED SNOW SHOWERS THIS
EVENING. THE MAIN DETRIMENT TO THE SNOW OCCURRING DOWN HERE IS
PROBABLY WITH THE PRECIPITATION RATES NOT BEING AS HIGH COMPARED
TO WHAT IS CURRENTLY OCCURRING IN SOUTHWEST ONTARIO. THAT MAY
MEAN THAT THE ICE CRYSTAL/SNOWFLAKE HAS A LONGER RESIDENCE TIME IN
THE SHALLOW LAYER OF 0 TO +2C AIR FROM THE SFC UP TO 2KFT THAT
WILL ALLOW FOR IT TO MELT. SO...IT STILL LOOKS LIKE A FEW
SNOWFLAKES COULD FLY ACROSS CLARK/TAYLOR/JACKSON COUNTIES
OVERNIGHT...PARTICULARLY IN HIGHER ELEVATIONS...BUT NOTHING STRONG
ENOUGH THAT ANY ACCUMULATIONS SHOULD OCCUR.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
256 PM CDT FRI SEP 21 2012
LATEST GFS AND ECMWF IN GENERALLY GOOD AGREEMENT THROUGH WEDNESDAY.
BOTH MODELS SHOW A WEAK COLD FRONT DROPPING SOUTH ACROSS THE AREA
MONDAY/MONDAY NIGHT WITH MORE OR LESS JUST A WIND SHIFT EXPECTED.
PLAN ON HIGHS MONDAY AND TUESDAY IN THE MID 60S TO A FEW LOWER 70S.
A SLIGHTLY COOLER AIR MASS SEEPS INTO THE AREA ON WEDNESDAY WITH
HIGHS IN THE 60S. FOR THURSDAY INTO FRIDAY...THE 21.12Z GFS SHOWS A
WEAK MID-LEVEL TROUGH ROTATING ACROSS THE CENTRAL CONUS WITH ANY PCPN
STAYING SOUTH OF OUR AREA. THE ECMWF SHOWS MORE VIGOROUS TROUGHING
INTO THE AREA AND THUS PRODUCES SOME PCPN FOR THE AREA THURSDAY
NIGHT INTO FRIDAY. WILL STICK WITH A DRY FORECAST FOR NOW AND GO
WITH MODEL CONSENSUS TEMPERATURES...WHICH YIELDS HIGHS THURSDAY AND FRIDAY
IN THE 60S.
&&
.AVIATION...TONIGHT AND SATURDAY
644 PM CDT FRI SEP 21 2012
A STRONG COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT WITH
DETERIORATING CONDITIONS FOLLOWING ITS PASSAGE. THIS FRONT IS
CURRENTLY UP IN NORTHERN TO CENTRAL MINNESOTA AND IS TIMED TO
REACH RST AROUND 4Z AND LSE AROUND 5Z. WINDS WILL BECOME VERY
GUSTY AS IT PASSES WITH SOME GUSTS IN THE 25 TO 35KT RANGE
OVERNIGHT. RAIN SHOWER CHANCES WILL BEGIN AS THE FRONT COMES
THROUGH WITH LSE MORE LIKELY TO SEE A MORE PROLONGED RAIN THROUGH
THE EARLY MORNING HOURS SATURDAY. INDICATIONS ARE THAT CEILINGS
WILL ALSO DROP TO MVFR IN THE 1000-1500FT RANGE AFTER 6Z AT RST
AND 8Z AT LSE. HAVE GONE ON THE PESSIMISTIC SIDE WITH KEEPING
THESE LOW CEILINGS AROUND THROUGH THE MORNING AND EARLY AFTERNOON
HOURS WHILE SOME OF THE SHORT TERM FORECAST GUIDANCE SUGGEST THAT
THEY WILL CLEAR SOONER THAN THAT. WINDS WILL STAY GUSTY THROUGHOUT
SATURDAY...THOUGH THE GUSTS WILL BE MORE IN THE 20-25KT RANGE OUT
OF THE NORTHWEST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT FRI SEP 21 2012
WI...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
MNZ079-086>088-094>096.
IA...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...HALBACH
LONG TERM....DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
644 PM CDT FRI SEP 21 2012
.SHORT TERM...TONIGHT THROUGH MONDAY
256 PM CDT FRI SEP 21 2012
FORECAST CONCERNS INCLUDE RAIN TONIGHT INTO SATURDAY/POSSIBLE RAIN
AND SNOW MIX...THEN INCREASING CONFIDENCE FOR A WIDESPREAD FREEZE
SATURDAY NIGHT.
THIS AFTERNOON/S WATER VAPOR IMAGERY FEATURES A DEEP LONGWAVE TROUGH
ENTRENCHED ACROSS EASTERN CANADA/CENTRAL CONUS. EMBEDDED WITHIN THIS
LARGE TROUGH WAS A FAIRLY WEAK SHORTWAVE TROUGH ZIPPING EAST ACROSS
SOUTHERN WI. IMPRESSIVE 700MB CONVERGENCE PER THE RAP ENOUGH TO
SQUEEZE OUT FAIRLY STEADY LIGHT-MODERATE RAIN AREA ACROSS SOUTHERN
WI/NORTHERN IL. COOL CYCLONIC FLOW ALOFT/STEEP LAPSE RATES ALSO
PRODUCING SCATTERED SHOWERS ACROSS NORTHERN/CENTRAL WI. A STRONGER
SHORTWAVE TROUGH WAS LOCATED OVER SOUTHEASTERN MANITOBA DROPPING
SOUTHWARD TOWARD OUR AREA. THIS WAVE WILL BE OUR WEATHER-MAKER
TONIGHT INTO SATURDAY. OTHERWISE...AFTERNOON TEMPERATURES WERE
SOME 10 DEGREES BELOW SEASONAL NORMALS WITH READINGS AT 2 PM IN THE
MIDDLE 50S TO LOWER 60S.
21.12Z NCEP MODEL SUITE ALONG WITH THE 21.09Z SREF ALL IN GREAT
AGREEMENT THROUGH THE SHORT TERM...LENDING TO FAIRLY HIGH FORECAST
CONFIDENCE.
FOR TONIGHT...THE AFOREMENTIONED MID-LEVEL SHORTWAVE OVER
SOUTHEASTERN MANITOBA WILL SWING SOUTH INTO THE AREA. NAM INDICATING
STRONG/DEEP PV-ADVECTION IN THE 850-300MB LAYER ALONG WITH
IMPRESSIVE QG RESPONSE...ESPECIALLY IN THE 700-500MB LAYER. GIVEN
STRONG/CONSISTENT SIGNAL...GOING WITH DEFINITE RAIN SHOWERS ALONG
AND NORTHEAST OF THE MISSISSIPPI RIVER MAINLY AFTER MIDNIGHT. LOOKING AT
THE NAM PLAN VIEW/BUFKIT DATA SHOWS WETBULB ZERO HEIGHTS GETTING
PRETTY LOW WHERE RAIN SHOWERS WILL BE OCCURRING....HOVERING
AROUND 2000 FEET AGL IN SOME CASES. THIS BEING THE CASE...WILL
CONTINUE THE POSSIBILITY OF SOME SNOW MIXING IN AT TIMES FOR AREAS
MAINLY ALONG AND NORTHEAST OF I-94. HOWEVER...WITH SUCH WARM
GROUND YET...NO ACCUMULATION IS EXPECTED.
LOOKS LIKE SOME LINGERING DEFORMATION AREA SHOWERS FOR SATURDAY
MORNING ACROSS SOUTHERN WI AS THE WAVE MOVES OFF TO THE EAST.
OTHERWISE...SUBSIDENCE BUILDS IN FOR THE REST OF THE DAY ALONG WITH
INCREASING PRESSURE GRADIENT BETWEEN DEPARTING WAVE AND HIGH
PRESSURE BUILDING IN FROM THE DAKOTAS. INCREASED WIND SPEEDS A BIT
TO ACCOUNT FOR THIS. PLAN ON BREEZY NORTHWEST WINDS IN THE 15 TO 25
MPH RANGE WITH HIGHS ONLY IN THE 50S. WILL DEFINITELY FEEL LIKE AN
AUTUMN DAY TO USHER THE FIRST DAY OF AUTUMN...WHICH STARTS AT 949 AM
CDT.
ALL ATTENTION THEN TURNS TO HOW COLD WILL IT GET SATURDAY NIGHT AND
THE POTENTIAL FOR A WIDESPREAD FREEZE. HIGH PRESSURE CONTINUES TO
MOVE TOWARD THE REGION FROM THE DAKOTAS...SPILLING CHILLY AIR INTO
THE REGION. NAM DEPICTING 850MB LAYER TEMPERATURES LOWERING INTO THE
ZERO TO -4C RANGE ACROSS THE AREA BY 12Z SUNDAY UNDER CLEAR SKIES.
THIS WOULD NORMALLY LEAD TO WIDESPREAD FREEZING TEMPERATURES AT THE
SURFACE. ONE CONCERN HOWEVER WILL BE WIND AND AMOUNT OF DECOUPLING
WITH THE RIDGE AXIS REMAINING WEST OF THE AREA ALL NIGHT. BOTH GFS AND
NAM SHOW PRESSURE GRADIENT SLACKENING GOING INTO SATURDAY EVENING.
GIVEN THIS...COULD SEE WINDS STAYING UP AROUND 5 MPH OR SO...LEADING
TO SOME STIRRING/MIXING OF THE LOWER BOUNDARY LAYER WHICH WOULD IN
TURN PREVENT TEMPERATURES FROM DROPPING MUCH BELOW THE FREEZING
MARK. HOWEVER...IF WE DO DECOUPLE AND GO CALM...TEMPERATURES COULD
REALLY TAKE A TUMBLE FOR A WIDESPREAD HARD FREEZE. WITH THIS IN
MIND...WILL GO AHEAD AN POST A FREEZE WATCH VALID FROM 1 AM THROUGH
8 AM SATURDAY.
REST OF SUNDAY INTO MONDAY LOOKS QUIET WITH A WARMING TREND AS THE
DEEP TROUGH THAT WAS ENTRENCHED ACROSS THE AREA STARTS TO FILL A BIT
AND LIFT NORTHEAST. LOOKS LIKE HIGHS WILL BE IN THE 50S TO LOWER 60S ON
SUNDAY...WARMING INTO THE 60S TO A FEW LOWER 70S ON MONDAY.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
256 PM CDT FRI SEP 21 2012
LATEST GFS AND ECMWF IN GENERALLY GOOD AGREEMENT THROUGH WEDNESDAY.
BOTH MODELS SHOW A WEAK COLD FRONT DROPPING SOUTH ACROSS THE AREA
MONDAY/MONDAY NIGHT WITH MORE OR LESS JUST A WIND SHIFT EXPECTED.
PLAN ON HIGHS MONDAY AND TUESDAY IN THE MID 60S TO A FEW LOWER 70S.
A SLIGHTLY COOLER AIR MASS SEEPS INTO THE AREA ON WEDNESDAY WITH
HIGHS IN THE 60S. FOR THURSDAY INTO FRIDAY...THE 21.12Z GFS SHOWS A
WEAK MID-LEVEL TROUGH ROTATING ACROSS THE CENTRAL CONUS WITH ANY PCPN
STAYING SOUTH OF OUR AREA. THE ECMWF SHOWS MORE VIGOROUS TROUGHING
INTO THE AREA AND THUS PRODUCES SOME PCPN FOR THE AREA THURSDAY
NIGHT INTO FRIDAY. WILL STICK WITH A DRY FORECAST FOR NOW AND GO
WITH MODEL CONSENSUS TEMPERATURES...WHICH YIELDS HIGHS THURSDAY AND FRIDAY
IN THE 60S.
&&
.AVIATION...TONIGHT AND SATURDAY
644 PM CDT FRI SEP 21 2012
A STRONG COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT WITH
DETERIORATING CONDITIONS FOLLOWING ITS PASSAGE. THIS FRONT IS
CURRENTLY UP IN NORTHERN TO CENTRAL MINNESOTA AND IS TIMED TO
REACH RST AROUND 4Z AND LSE AROUND 5Z. WINDS WILL BECOME VERY
GUSTY AS IT PASSES WITH SOME GUSTS IN THE 25 TO 35KT RANGE
OVERNIGHT. RAIN SHOWER CHANCES WILL BEGIN AS THE FRONT COMES
THROUGH WITH LSE MORE LIKELY TO SEE A MORE PROLONGED RAIN THROUGH
THE EARLY MORNING HOURS SATURDAY. INDICATIONS ARE THAT CEILINGS
WILL ALSO DROP TO MVFR IN THE 1000-1500FT RANGE AFTER 6Z AT RST
AND 8Z AT LSE. HAVE GONE ON THE PESSIMISTIC SIDE WITH KEEPING
THESE LOW CEILINGS AROUND THROUGH THE MORNING AND EARLY AFTERNOON
HOURS WHILE SOME OF THE SHORT TERM FORECAST GUIDANCE SUGGEST THAT
THEY WILL CLEAR SOONER THAN THAT. WINDS WILL STAY GUSTY THROUGHOUT
SATURDAY...THOUGH THE GUSTS WILL BE MORE IN THE 20-25KT RANGE OUT
OF THE NORTHWEST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT FRI SEP 21 2012
WI...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
MNZ079-086>088-094>096.
IA...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...DAS
LONG TERM....DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS TAUNTON MA
416 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A SHORT PERIOD OF HIGH PRESSURE WILL BRING A BRIEF WARM UP
TODAY AFTER SKIES CLEAR IN THE MORNING. A COLD FRONT WILL THEN
BRING SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS LATE
TODAY INTO TONIGHT. HIGH PRESSURE AND DRIER CONDITIONS BUILD INTO
NEW ENGLAND SUNDAY WITH COOLER WEATHER FOR THE FIRST HALF OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BANK OF STRATUS STILL BUILDING OVER SRN NEW ENGLAND THIS HOUR AS
WEAK SFC WARM FRONT SHIFTS INTO NRN NEW ENGLAND. NAM/RGEM HANDLING
THIS STRATUS WELL SO ADJUSTED SKIES TOWARD ITS SOLN. GIVEN THE
INCREASING DWPTS AND SUBSIDENCE BENEATH THE WEAK RIDGE...IT MAY
TAKE SOME TIME FOR THIS STRATUS TO COMPLETELY BREAK...BUT BL
MIXING SHOULD TAKE OVER BY ABOUT MID MORNING GIVEN THE EXPECTED
INSOLATION IN THE DRY SUBSIDENCE. THE STRATUS WILL LIKELY DELAY
DIURNAL TEMP INCREASE HOWEVER...SO ADJUSTED TOWARD THE 5 DAY BIAS
CORRECTED GRIDS ALONG WITH THE MOST RECENT HRRR WHICH SUPPORTED
THIS THINKING.
STRONG KICKER WAVE WILL BE FORCING PERSISTENT GREAT LAKES CUTOFF
TO BEGIN MIGRATION N WITH TIME...ALONG WITH A SFC LOW PRES SYSTEM.
THIS WILL ALLOW A COLD FRONT TO BEGIN MOVING TOWARD THE REGION BY
LATE IN THE DAY. THE COMBINATION OF COOLING TEMPERATURES ALOFT
WITH THIS WAVE...SFC DIABATIC WARMING AFTER THE STRATUS CLEARS...
AND SFC DWPT RISES IN MOISTENING SLY FLOW...WILL LEAD TO MODEST
DESTABILIZATION OF THE COLUMN AS THE FRONT APPROACHES. SB CAPE
VALUES ARE FORECAST TO ONLY REACH 500-1000 J/KG BY LATE DAY. GIVEN
THE LATE ARRIVAL OF THE FRONT /ON THE DOORSTEP OF WRN MA BY
00Z/...WEAKENING DYNAMICS AS THE BEST JET ENERGY LIFTS N WITH THE
WAVE...AND A VERY DRY COLUMN /PWAT VALUES STRUGGLE TO BREAK 1.25
INCHES/ IT WILL LIKELY TAKE MOST OF THE DAY FOR ANY POTENTIAL
PRECIP/TSTMS TO GET GOING. THERE IS SOME MODERATE SHEAR WITH AN
H85 JET BETWEEN 30 AND 40 KT TO WORK WITH...BUT WITH MODEST
INSTABILITY AND DRY AIR THE BEST CHANCE FOR STORMS WILL LIKELY BE
UPSTREAM. WITH A HIGHER SHEAR...LOWER INSTABILITY SCENARIO...WILL
LIKELY NEED TO MONITOR FOR A THIN LINE OF LOW TOPPED CONVECTION
CLOSELY ASSOCIATED WITH THE FRONT ITSELF...WHICH WOULD ARRIVE BY
LATE EVENING. ANY BOWING SECTIONS MAY BE ABLE TO TAP SOME OF THE
JET ENERGY. GIVEN ALL OF THESE FACTORS...HAVE LIMITED POPS MUCH OF
THE DAY...WITH LIKELY POPS ONLY REACH THE EAST SLOPES OF THE
BERKSHIRES BY LATE 00Z. SPC CONTINUES TO KEEP SLIGHT RISK JUST TO
THE W OF THE CWA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
SFC COLD FRONT WILL BE MOVING RAPIDLY THROUGH THE AREA AS STRONG
KICKER TROF FORCES LONGWAVE AND ASSOCIATED LOW PRES INTO CANADA.
GIVEN THIS...THE BEST DYNAMICS AND FGEN EXIT TO THE N WITH TIME.
SO EXPECT THE FRONT TO RAPIDLY WEAKEN AND STRETCH OUT WITH
TIME...ESPECIALLY AS IT INTERACTS WITH PERSISTENTLY DRY COLUMN
OVER ERN PORTIONS OF THE FA. HAVE POPS DIMINISHING RAPIDLY
ESPECIALLY AFTER MIDNIGHT LOCAL. WITH LOSS OF DIURNAL HEATING AND
DRIER MORE STABLE AIRMASS TO THE E...THE WEAKENING SOURCE OF
LIFT...TSTMS/SHOWERS WILL LIKELY BE GRADUALLY DIMINISHING WITH
TIME. ALTHOUGH WE HAVE SLIGHT CHANCE POPS FOR ERN COUNTIES...IT IS
POSSIBLE THAT SOME AREAS MAY SEE LITTLE TO NO PRECIP AT ALL.
WILL NEED TO CONTINUE TO MONITOR FOR A FINE LINE AS MENTIONED
ABOVE HOWEVER...ESPECIALLY IN THE EARLY OVERNIGHT HOURS...WHICH
MAY PROVIDE SOME GUSTY WINDS AND BRIEF HEAVY RAINFALL...BUT THIS
REMAINS A THREAT MOSTLY W OF THE WORCESTER HILLS.
SUN...
GIVEN THAT TIMING OF THE FRONT IS GENERALLY WELL AGREED UPON BY
MODELS...HAVE REASONABLY HIGH CONFIDENCE THAT IT SHOULD BE MOVING
E OF CAPE COD BY 12Z. WITH STRONG COOL ADVECTION AND NW FLOW
SHOULD SEE SOME RAPIDLY EARLY DAY CLEARING FROM W TO E AS THE DRY
COOL AIRMASS WORKS ITS WAY IN. MODELS MAY BE STRUGGLING SOMEWHAT
IN THIS EARLY FALL CAA REGIME AS RAW DATA SUGGESTS SKC CONDITIONS
AND LIGHT WINDS FOR MUCH OF THE DAY. SOUNDINGS SHOW 15 TO 20 KT
AVAILABLE FOR DAYTIME MIXING AND SOME TRAPPED MOISTURE AROUND
H9-H8. THEREFORE...HAVE INCREASED MID DAY CLOUDINESS AND WIND
GUSTS SOMEWHAT FROM GRIDDED MODEL DATA. OTHERWISE A MOSTLY DRY
DAY. H85 TEMPERATURES WILL BE COOLING WITH TIME BUT ONLY REACH
ABOUT +6C BY PEAK HEATING...THEREFORE TEMPERATURES IN THE UPPER
60S TO LOWER 70S WILL LIKELY REMAIN.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
BIG PICTURE...
NO MAJOR CHANGES NOTED WITH THE 22/00Z MODEL SUITE FROM THE 21/12Z
GUIDANCE. 22/00Z GUIDANCE IS STILL IN DECENT AGREEMENT WITH THE
OVERALL SYNOPTIC PATTERN NEXT WEEK...WITH SOME TIMING DIFFERENCES
STILL.
EARLY WEEK PATTERN SHOWS RIDGE WEST/TROUGH EAST WITH A CLOSED LOW
IN THE VICINITY JAMES BAY CANADA. THIS CONTINUES THROUGH MIDWEEK
AS THE WESTERN RIDGE SLOWLY DE-AMPLIFIES. ONE SHORTWAVE ROTATES
THROUGH THE EASTERN CYCLONIC FLOW AND CROSSES NEW ENGLAND MONDAY.
THIS TROUGH ITSELF BECOMES PROGRESSIVE MIDWEEK WITH THE TROUGH
AXIS CROSSING NEW ENGLAND AROUND THURSDAY.
THE MODEL SOLUTIONS AT 500 MB ARE CONSISTENT THROUGH MONDAY. THE
22/00Z GFS AND GGEM ARE FASTER TO EJECT THE CLOSED LOW EAST BY
WEDNESDAY. MEANWHILE THE 22/00Z ECMWF HOLDS IT OVER EASTERN CANADA
UNTIL THURSDAY. BOTH THE GFS AND ECMWF MOVE THE TROUGH AXIS OR A
SEMBLANCE OF ONE THROUGH OUR AREA ABOUT THURSDAY.
MONDAY...
THIS IS A TRICKY FORECAST PERIOD. EXPECTING A FAIRLY POTENT
SHORTWAVE TO MOVE ACROSS SOUTHERN NEW ENGLAND DURING THIS PERIOD.
THE MAIN QUESTION LEFT TO BE ANSWERED WILL BE THE AMOUNT OF
MOISTURE AVAILABLE TO BE PUT INTO CLOUDS AND SHOWERS. AS MENTIONED
BY PREVIOUS SHIFT...THIS PATTERN DOES FAVOR AT LEAST SOME DIURNAL
CLOUDS. THINKING WHILE THERE MAY BE ENOUGH MOISTURE FOR SOME
CLOUDS...THERE IS NOT ENOUGH TO WARRANT MORE THAN A VERY LOW
CHANCE FOR RAINFALL.
ANY CLOUDS AND SHOWERS SHOULD DISSIPATE QUICKLY AFTER SUNSET
MONDAY EVENING.
TUESDAY...
SURFACE HIGH PRESSURE BUILDS OVER THE REGION. SHOULD BE A FAIR
WEATHER DAY. WARM ADVECTION ALOFT WILL CAP THE MIXED LAYER/KEEP IT
LOWER. MIXED TEMPERATURES FROM ALOFT SHOULD BE EQUIVALENT OF 5-7C
AT 850 MB...SUPPORTING MAX SURFACE TEMPERATURES AROUND 70F.
WEDNESDAY-THURSDAY...
THE TROUGH AXIS APPROACHES WEDNESDAY AND MOVES THROUGH WEDNESDAY
NIGHT OR THURSDAY. SOUTHWEST SURFACE WINDS WILL BRING WARMER
TEMPERATURES AND HIGHER DEW POINTS /50S/. THIS UPPER TROUGH WILL BE
IN THE ST LAWRENCE VALLEY IN THE AFTERNOON...SO EXPECT MOST
RAINFALL TO REMAIN NORTH OF OUR AREA. COULD BE CHANCE POPS TOWARD
WEDNESDAY EVENING ACROSS OUR NORTHERN AREAS. SHOWERS THEN MOVE
ACROSS SOUTHERN NEW ENGLAND WEDNESDAY NIGHT AND THURSDAY...ENDING
WITH THE WIND SHIFT. CHANCE POPS DURING THIS PERIOD. TEMPERATURES
ARE A BLEND OF HPC AND GMOS.
FRIDAY...
HIGH PRESSURE BUILDS WITH FAIR DRY WEATHER. USED A BLEND OF HPC
AND GMOS GUIDANCE.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN TIMING.
AREA OF STRATUS AND FOG WILL CONTINUE TO FILL IN OVER THE REGION
INTO THE DAYLIGHT HOURS. THIS WILL YIELD WIDESPREAD MVFR/IFR
CONDITIONS. AFTER SUNRISE...EXPECT CONDITIONS TO GRADUALLY
IMPROVE...BUT IT WILL LIKELY TAKE UNTIL 15Z OR SO BEFORE MOST
STRATUS LIFTS TO VFR.
VFR THEN CONTINUES THROUGH THE DAY TODAY UNTIL A WEAKENING FRONT
MOVES THROUGH TONIGHT. THERE IS THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WITH BRIEF MVFR CONDITIONS PARTICULARLY W OF ORH IN
THE EVENING...BUT GIVEN THE FRONT WILL BE WEAKENING WITH TIME
CONDITIONS SHOULD IMPROVE TO VFR DESPITE THE FROPA.
KBOS TAF...
HIGH CONFIDENCE TAF TRENDS...BUT LOWER CONFIDENCE IN TIMING.
MVFR/IFR CONDITIONS GRADUALLY LIFT AFTER SUNRISE WITH VFR LIKELY
LINGERING INTO THE OVERNIGHT HOURS. A FAST MOVING FRONT WILL BRING
THE LOW PROB OF SHOWERS TONIGHT...BUT CONDITIONS REMAIN MOSTLY
VFR.
KBDL TAF...MODERATE CONFIDENCE IN TAF.
VFR WILL DOMINATE EXCEPT FOR SOME MVFR POSSIBLE INTO THE EARLY
MORNING HOURS THIS MORNING WITH STRATUS. IMPROVEMENT TO VFR DURING
THE DAY SAT.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MODERATE CONFIDENCE. VFR EXPECTED.
&&
.MARINE...
MODERATE CONFIDENCE.
A BUILDING EASTERLY SWELL WILL BEGIN TO EFFECT E WATERS
FIRST...LIKELY RISING TO ABOUT 5-6 FT OVER THE OUTER WATERS BY MID
MORNING. IT WILL TAKE SOME TIME FOR THE S WATERS TO REACH 5
FT...BUT IT WILL LIKELY BUILD TO THIS LEVEL BY LATE THIS EVENING
AS WELL. THEREFORE...A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS HAS
BEEN ISSUED FOR THE OUTER WATERS AND NANTUCKET SOUND FR THIS
EASTERLY SWELL.
OTHERWISE...WINDS WILL GENERALLY REMAIN BELOW 25 KT THROUGH THE
PERIOD...HOWEVER A COLD FRONT WILL CROSS THE WATERS TONIGHT WITH
THE CHANCE FOR SOME BRIEF 20-30 KT GUSTS IN SHOWERS AND ISOLATED
THUNDERSTORMS...THE BEST CHANCE WILL BE SOUTHERN WATERS.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE.
MONDAY AND TUESDAY...MODERATE CONFIDENCE. DIMINISHING WINDS AND
SEAS AS HIGH PRESSURE BUILDS. NO HEADLINES ARE ANTICIPATED.
WEDNESDAY...MODERATE CONFIDENCE.
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT LEVELS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 8 PM THIS EVENING
TO 8 AM EDT SUNDAY FOR ANZ232-251-256.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT SUNDAY
FOR ANZ250-254-255.
&&
$$
SYNOPSIS...DOODY/BELK
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...BELK
AVIATION...DOODY/BELK
MARINE...DOODY/BELK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
339 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A SHORT PERIOD OF HIGH PRESSURE WILL BRING A BRIEF WARM UP
TODAY AFTER SKIES CLEAR IN THE MORNING. A COLD FRONT WILL THEN
BRING SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS LATE
TODAY INTO TONIGHT. HIGH PRESSURE AND DRIER CONDITIONS BUILD INTO
NEW ENGLAND SUNDAY WITH COOLER WEATHER FOR THE FIRST HALF OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BANK OF STRATUS STILL BUILDING OVER SRN NEW ENGLAND THIS HOUR AS
WEAK SFC WARM FRONT SHIFTS INTO NRN NEW ENGLAND. NAM/RGEM HANDLING
THIS STRATUS WELL SO ADJUSTED SKIES TOWARD ITS SOLN. GIVEN THE
INCREASING DWPTS AND SUBSIDENCE BENEATH THE WEAK RIDGE...IT MAY
TAKE SOME TIME FOR THIS STRATUS TO COMPLETELY BREAK...BUT BL
MIXING SHOULD TAKE OVER BY ABOUT MID MORNING GIVEN THE EXPECTED
INSOLATION IN THE DRY SUBSIDENCE. THE STRATUS WILL LIKELY DELAY
DIURNAL TEMP INCREASE HOWEVER...SO ADJUSTED TOWARD THE 5 DAY BIAS
CORRECTED GRIDS ALONG WITH THE MOST RECENT HRRR WHICH SUPPORTED
THIS THINKING.
STRONG KICKER WAVE WILL BE FORCING PERSISTENT GREAT LAKES CUTOFF
TO BEGIN MIGRATION N WITH TIME...ALONG WITH A SFC LOW PRES SYSTEM.
THIS WILL ALLOW A COLD FRONT TO BEGIN MOVING TOWARD THE REGION BY
LATE IN THE DAY. THE COMBINATION OF COOLING TEMPS ALOFT WITH THIS
WAVE...SFC DIABATIC WARMING AFTER THE STRATUS CLEARS...AND SFC
DWPT RISES IN MOISTENING SLY FLOW...WILL LEAD TO MODEST
DESTABILIZATION OF THE COLUMN AS THE FRONT APPROACHES. SB CAPE
VALUES ARE FORECAST TO ONLY REACH 500-1000 J/KG BY LATE DAY. GIVEN
THE LATE ARRIVAL OF THE FRONT /ON THE DOORSTEP OF WRN MA BY
00Z/...WEAKENING DYNAMICS AS THE BEST JET ENERGY LIFTS N WITH THE
WAVE...AND A VERY DRY COLUMN /PWAT VALUES STRUGGLE TO BREAK 1.25
INCHES/ IT WILL LIKELY TAKE MOST OF THE DAY FOR ANY POTENTIAL
PRECIP/TSTMS TO GET GOING. THERE IS SOME MODERATE SHEAR WITH AN
H85 JET BETWEEN 30 AND 40 KT TO WORK WITH...BUT WITH MODEST
INSTABILITY AND DRY AIR THE BEST CHANCE FOR STORMS WILL LIKELY BE
UPSTREAM. WITH A HIGHER SHEAR...LOWER INSTABILITY SCENARIO...WILL
LIKELY NEED TO MONITOR FOR A THIN LINE OF LOW TOPPED CONVECTION
CLOSELY ASSOCIATED WITH THE FRONT ITSELF...WHICH WOULD ARRIVE BY
LATE EVENING. ANY BOWING SECTIONS MAY BE ABLE TO TAP SOME OF THE
JET ENERGY. GIVEN ALL OF THESE FACTORS...HAVE LIMITED POPS MUCH OF
THE DAY...WITH LIKELY POPS ONLY REACH THE EAST SLOPES OF THE
BERKSHIRES BY LATE 00Z. SPC CONTINUES TO KEEP SLIGHT RISK JUST TO
THE W OF THE CWA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
SFC COLD FRONT WILL BE MOVING RAPIDLY THROUGH THE AREA AS STRONG
KICKER TROF FORCES LONGWAVE AND ASSOCIATED LOW PRES INTO CANADA.
GIVEN THIS...THE BEST DYNAMICS AND FGEN EXIT TO THE N WITH TIME.
SO EXPECT THE FRONT TO RAPIDLY WEAKEN AND STRETCH OUT WITH
TIME...ESPECIALLY AS IT INTERACTS WITH PERSISTENTLY DRY COLUMN
OVER ERN PORTIONS OF THE FA. HAVE POPS DIMINISHING RAPIDLY
ESPECIALLY AFTER MIDNIGHT LOCAL. WITH LOSS OF DIURNAL HEATING AND
DRIER MORE STABLE AIRMASS TO THE E...THE WEAKENING SOURCE OF
LIFT...TSTMS/SHOWERS WILL LIKELY BE GRADUALLY DIMINISHING WITH
TIME. ALTHOUGH WE HAVE SLIGHT CHANCE POPS FOR ERN COUNTIES...IT IS
POSSIBLE THAT SOME AREAS MAY SEE LITTLE TO NO PRECIP AT ALL. WILL
NEED TO CONTINUE TO MONITOR FOR A FINE LINE AS MENTIONED ABOVE
HOWEVER...ESPECIALLY IN THE EARLY OVERNIGHT HOURS...WHICH MAY
PROVIDE SOME GUSTY WINDS AND BRIEF HEAVY RAINFALL...BUT THIS
REMAINS A THREAT MOSTLY W OF THE WORCESTER HILLS.
SUN...
GIVEN THAT TIMING OF THE FRONT IS GENERALLY WELL AGREED UPON BY
MODELS...HAVE REASONABLY HIGH CONFIDENCE THAT IT SHOULD BE MOVING
E OF CAPE COD BY 12Z. WITH STRONG COOL ADVECTION AND NW FLOW
SHOULD SEE SOME RAPIDLY EARLY DAY CLEARING FROM W TO E AS THE DRY
COOL AIRMASS WORKS ITS WAY IN. MODELS MAY BE STRUGGLING SOMEWHAT
IN THIS EARLY FALL CAA REGIME AS RAW DATA SUGGESTS SKC CONDITIONS
AND LIGHT WINDS FOR MUCH OF THE DAY. SOUNDINGS SHOW 15 TO 20 KT
AVAILABLE FOR DAYTIME MIXING AND SOME TRAPPED MOISTURE AROUND
H9-H8. THEREFORE...HAVE INCREASED MID DAY CLOUDINESS AND WIND
GUSTS SOMEWHAT FROM GRIDDED MODEL DATA. OTHERWISE A MOSTLY DRY
DAY. H85 TEMPS WILL BE COOLING WITH TIME BUT ONLY REACH ABOUT +6C
BY PEAK HEATING...THEREFORE TEMPS IN THE UPPER 60S TO LOWER 70S
WILL LIKELY REMAIN.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
BIG PICTURE...
EARLY WEEK PATTERN SHOWS RIDGE WEST/TROUGH EAST WITH CLOSED LOW
VICINITY JAMES BAY CANADA. THIS CONTINUES THROUGH MIDWEEK AS THE
WESTERN RIDGE SLOWLY DE-AMPLIFIES. ONE SHORTWAVE ROTATES THROUGH
THE EASTERN CYCLONIC FLOW AND CROSSES NEW ENGLAND ON MONDAY. THE
TROUGH ITSELF BECOMES PROGRESSIVE MIDWEEK WITH THE TROUGH AXIS
CROSSING NEW ENGLAND AROUND THURSDAY.
THE MODEL SOLUTIONS AT 500 MB ARE CONSISTENT THROUGH MONDAY. THE
GFS IS FASTER IN EJECTING THE CLOSED LOW EAST BY WEDNESDAY WHILE THE
GGEM AND ECMWF HOLD IT OVER EASTERN CANADA UNTIL THURSDAY. BOTH THE
GFS AND ECMWF MOVE THE TROUGH AXIS OR A SEMBLANCE OF ONE THROUGH OUR
AREA ON THURSDAY.
SUNDAY...
COLD FRONT MOVES EAST OF THE REGION EARLY IN THE DAY. WINDS SHOULD
BE WEST THROUGH THE DAY. WITH DRIER AIR MOVING IN WE SHOULD HAVE A
MOSTLY SUNNY DAY. MIXING DEPTH REACHES 850 MB...WHERE WINDS ARE
FORECAST AT 15-20 KTS. EXPECT GUSTS IN THIS RANGE. TEMPS AT 850 MB
WILL BE FALLING THROUGH THE DAY...BUT WILL BE 5-7C EARLY AFTERNOON.
SO EXPECT MAX TEMPS IN THE UPPER 60S AND LOWER 70S. AFTER SUNSET
WINDS IN THE INTERIOR SHOULD DECOUPLE AND ALLOW FAST COOLING. WITH
DEWPOINTS AROUND 40 THAT SHOULD ALLOW FOR MIN TEMPS SUNDAY NIGHT IN
THE 40S.
MONDAY...
MODEL GRIDS ADVERTISE ANOTHER SUNNY DAY. BUT PATTERN SHOWN BY THE
MODELS IS NOT ONE THAT WOULD NORMALLY BRING A SUNNY QUIET WEATHER
DAY. A SHARP UPPER SHORTWAVE MOVES OVER NEW ENGLAND DURING THE DAY
WITH 500 MB TEMPS -22C TO -25C AND TOTALS OF 46 TO 50. RELATIVE
HUMIDITY TIME SECTIONS SHOW VALUES OF 70-80 PERCENT BETWEEN 800
AND 900 MB OVER MUCH OF SOUTHERN NEW ENGLAND DURING THE DAY. ALL
OF THIS SUGGESTS DIURNAL CUMULUS AND POSSIBLE SHOWERS ESPECIALLY
AT THE TIME OF SHORTWAVE PASSAGE. THE STRONGEST VALUES OF THE
VARIOUS PARAMETERS ARE IN NORTHERN NEW ENGLAND...BUT SOUTHERN
VALUES ARE NONE TOO SHABBY.
SO WE WILL BUCK THE TREND ON GUIDANCE AND GO WITH AFTERNOON SKY
COVER OF 45 TO 65 PERCENT...HIGHEST NORTH...AND ALSO POPS OF 15-20
PERCENT NORTH OF THE MASS PIKE. TEMPS AT 850 MB OF 2-4C WOULD
SUGGEST MAX TEMPS IN THE 60S.
CLEARING SKIES MONDAY NIGHT WITH LIGHT WINDS...SO ANOTHER NIGHT OF
RADIATIONAL COOLING WITH DEWPOINTS AROUND 40...SO MIN TEMPS SHOULD
BE IN THE UPPER 30S AND 40S.
TUESDAY...
SURFACE HIGH PRESSURE BUILDS OVER THE REGION. SHOULD BE A FAIR
WEATHER DAY. WARM ADVECTION ALOFT WILL CAP THE MIXED LAYER/KEEP IT
LOWER. MIXED TEMPS FROM ALOFT SHOULD BE EQUIVALENT OF 5-7C AT 850
MB...SUPPORTING MAX TEMPS AROUND 70F.
WEDNESDAY-THURSDAY...
THE TROUGH AXIS APPROACHES WEDNESDAY AND MOVES THROUGH WEDNESDAY
NIGHT OR THURSDAY. SOUTHWEST SURFACE WINDS WILL BRING WARMER TEMPS
AND HIGHER DEWPOINTS /50S/. THE UPPER TROUGH WILL BE IN THE ST
LAWRENCE VALLEY IN THE AFTERNOON SO EXPECT MOST PCPN TO REMAIN NORTH
OF OUR AREA...BUT COULD BE CHANCE POPS TOWARD WEDNESDAY EVENING IN
OUR NORTHERN AREAS. SHOWERS THEN MOVE ACROSS SOUTHERN NEW ENGLAND
WEDNESDAY NIGHT AND THURSDAY...ENDING WITH THE WIND SHIFT. CHANCE
POPS DURING THIS PERIOD. TEMPS ARE A BLEND OF HPC AND GMOS.
FRIDAY...
HIGH PRESSURE BUILDS WITH FAIR DRY WEATHER. USED A BLEND OF HPC
GRIDS AND GMOS GRIDS.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN TIMING.
AREA OF STRATUS AND FOG WILL CONTINUE TO FILL IN OVER THE REGION
INTO THE DAYLIGHT HOURS. THIS WILL YIELD WIDESPREAD MVFR/IFR
CONDITIONS. AFTER SUNRISE...EXPECT CONDITIONS TO GRADUALLY
IMPROVE...BUT IT WILL LIKELY TAKE UNTIL 15Z OR SO BEFORE MOST
STRATUS LIFTS TO VFR.
VFR THEN CONTINUES THROUGH THE DAY TODAY UNTIL A WEAKENING FRONT
MOVES THROUGH TONIGHT. THERE IS THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WITH BRIEF MVFR CONDITIONS PARTICULARLY W OF ORH IN
THE EVENING...BUT GIVEN THE FRONT WILL BE WEAKENING WITH TIME
CONDITIONS SHOULD IMPROVE TO VFR DESPITE THE FROPA.
KBOS TAF...
HIGH CONFIDENCE TAF TRENDS...BUT LOWER CONFIDENCE IN TIMING.
MVFR/IFR CONDITIONS GRADUALLY LIFT AFTER SUNRISE WITH VFR LIKELY
LINGERING INTO THE OVERNIGHT HOURS. A FAST MOVING FRONT WILL BRING
THE LOW PROB OF SHOWERS TONIGHT...BUT CONDITIONS REMAIN MOSTLY
VFR.
KBDL TAF...MODERATE CONFIDENCE IN TAF.
VFR WILL DOMINATE EXCEPT FOR SOME MVFR POSSIBLE INTO THE EARLY
MORNING HOURS THIS MORNING WITH STRATUS. IMPROVEMENT TO VFR DURING
THE DAY SAT.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MODERATE CONFIDENCE. VFR EXPECTED. NORTHWEST WINDS GUST TO 20
KNOTS MONDAY AFTERNOON.
&&
.MARINE...
MODERATE CONFIDENCE.
A BUILDING EASTERLY SWELL WILL BEGIN TO EFFECT E WATERS
FIRST...LIKELY RISING TO ABOUT 5-6 FT OVER THE OUTER WATERS BY MID
MORNING. IT WILL TAKE SOME TIME FOR THE S WATERS TO REACH 5
FT...BUT IT WILL LIKELY BUILD TO THIS LEVEL BY LATE THIS EVENING
AS WELL. THEREFORE...A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS HAS
BEEN ISSUED FOR THE OUTER WATERS AND NANTUCKET SOUND FR THIS
EASTERLY SWELL.
OTHERWISE...WINDS WILL GENERALLY REMAIN BELOW 25 KT THROUGH THE
PERIOD...HOWEVER A COLD FRONT WILL CROSS THE WATERS TONIGHT WITH
THE CHANCE FOR SOME BRIEF 20-30 KT GUSTS IN SHOWERS AND ISOLATED
THUNDERSTORMS...THE BEST CHANCE WILL BE SOUTHERN WATERS.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE.
SUNDAY...MODERATE CONFIDENCE.
WEST WINDS MAY APPROACH 25 KNOTS AT TIMES ESPECIALLY OFF THE SOUTH
COAST. SEAS OF 5 TO 6 FEET ON THE OUTER WATERS WILL MOSTLY REFLECT
A 5 FOOT EAST SWELL. SMALL CRAFT ADVISORIES ARE LIKELY.
MONDAY...MODERATE CONFIDENCE.
DIMINISHING WINDS AND SEAS AS HIGH PRESSURE BUILDS. NO HEADLINES
ARE ANTICIPATED.
TUESDAY...MODERATE CONFIDENCE.
INCREASING SOUTHWEST WINDS MAY REACH 25 KNOTS AT TIMES ESPECIALLY IN
THE AFTERNOON. A SMALL CRAFT ADVISORY MAY BE NEEDED.
WEDNESDAY...MODERATE CONFIDENCE.
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT LEVELS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 8 PM THIS EVENING
TO 8 AM EDT SUNDAY FOR ANZ232-251-256.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT SUNDAY
FOR ANZ250-254-255.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...BELK
AVIATION...BELK/DOODY
MARINE...BELK/DOODY
AREA FORECAST DISCUSSION
NWS NEW YORK NY
200 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE EAST COAST WILL GIVE WAY
TO LOW PRESSURE AND AN ASSOCIATED COLD FRONT LATE SATURDAY INTO
SATURDAY NIGHT. ANOTHER HIGH WILL BRING FAIR WEATHER SUNDAY INTO
WEDNESDAY. A COLD FRONT WILL MOVE THROUGH LATE WEDNESDAY INTO
EARLY THURSDAY...FOLLOWED AGAIN BY HIGH PRESSURE BUILDING INTO
FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MINOR ADJUSTMENTS MADE TO NEAR TERM GRIDS TO REFLECT LATEST TRENDS
IN OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
FOG AND LOW CLOUDS ALREADY EVIDENT IN A FEW SPOTS...AND WILL
MAINTAIN PATCHY FOG IN THE GRIDS FOR THE OVERNIGHT. RAP INDICATING
FOG/POSSIBLE STRATUS IN TIME HEIGHTS.
LOWS WERE WEIGHTED MORE TOWARDS THE COOLER MAV GUIDANCE WITH THE
EXPECTATION OF GREATER RADIATIONAL COOLING TAKING PLACE. LOWS
FORECAST RANGE FROM UPPER 40S TO LOWER 50S FOR INLAND AND RURAL
LOCATIONS...TO THE MID 50 TO LOWER 60S ACROSS THE REMAINDER OF THE
AREA.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
THE PARENT LOW IS SIMILAR TO THE ONE ON THIS PAST TUESDAY BUT IT
IS A LITTLE FURTHER WEST. HIGH PRESSURE OFFSHORE IS NEARLY THE
SAME. THEREFORE...THERE IS LESS OF A PRESSURE GRADIENT THAN ON
TUESDAY. THIS WILL BE A KEY COMPONENT TO ASSESSING WIND AND
THEREBY SEVERE WEATHER POTENTIAL.
WINDS EARLY ON SATURDAY MORNING WILL BE INITIALLY LIGHT AND UNDER 10
KT. ACCOUNTING FOR SCATTERING OUT OF CLOUDS IN THE MORNING WITH ANY
PATCHY FOG DISSIPATING WITH DIURNAL WARMING. CAPE WILL BE INCREASING
DURING THIS TIME FRAME TO ABOUT 500-100 J/KG AS WELL AS SOME INCREASE
IN VORTICITY. SO THIS POSITIVE VORTICITY ADVECTION AND INCREASING
INSTABILITY WILL CREATE THE FIRST CHANCE OF THUNDERSTORMS. THIS
WILL BE WELL AHEAD OF THE COLD FRONT IN THE FORM OF DISCRETE
CELLS. THE MODELS ARE NOT REALLY CAPTURING THIS POTENTIAL AHEAD OF
THE FRONT AS OF YET WITH EXCEPTION OF ECMWF AND SREF WHICH SHOWS
AT LEAST A FEW HUNDREDTHS OF AN INCH INTO FAR WESTERN PORTIONS OF
THE AREA BY 18Z SAT. THE 12Z RUN OF THE GFS ALSO HAS PROGRESSED
FARTHER EAST WITH ITS QPF FIELD COMPARED TO ITS PREVIOUS RUN IN
BETWEEN 12-18Z. THE ONE LIMITING FACTOR WILL BE THE MOISTURE AS
DEWPOINTS WILL STILL BE IN THE LOWER 60S EARLY SATURDAY MORNING
BUT WITH A STEADY INCREASE THEREAFTER FROM INCREASING LOW LEVEL
SOUTH TO SOUTHWEST FLOW...THIS WILL AUGMENT THETA-E ADVECTION IN
THE LOW LEVELS AND THE RATE SPIKES INITIALLY BETWEEN 12 AND 15Z
WITH AT LEAST A 7K/3HR INCREASE FOR WESTERN LOCATIONS AT 925MB.
THE BEST POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL SIMILAR THE
925MB THETA-E PROGRESSION OF AT LEAST 330K.
TAKING THIS INTO ACCOUNT...THE LIMITING MOISTURE FACTOR WILL KEEP
POPS LOW AT SLIGHT CHANCE AND GRADUALLY INCREASING CHANCES FROM WEST
TO EAST MID MORNING ONWARD AS THE TROUGH PUSHES CLOSER TO THE
REGION.
THE CAPE REALLY DROPS OFF ACROSS EASTERN COASTAL SECTIONS SO THEY
WILL HAVE MOST LIKELY DRY CONDITIONS WITH JUST A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON. WOULD NOT BE
SURPRISED IF THE WHOLE DAY IS DRY FOR EASTERN SECTIONS.
THE CAPE INCREASES TO AROUND 1000-1500 J/KG FOR THE LOWER HUDSON
VALLEY AND INTERIOR NORTHEAST NEW JERSEY AND BETWEEN 500-1000 J/KG
EAST ACROSS THE REST OF NORTHEAST NEW JERSEY...NEW YORK
CITY...WESTERN LONG ISLAND AND SOUTHWEST CONNECTICUT. THESE 500-1000
J/KG CAPE VALUES SPREAD MORE ACROSS LONG ISLAND SATURDAY NIGHT.
THE 0-6KM BULK SHEAR WILL BE MAINLY BETWEEN 30-40 KT AND THIS
COMBINED WITH THE CAPE WILL ALLOW FOR SOME THUNDERSTORMS TO BE
STRONG TO POSSIBLY SEVERE. LOW LEVEL JET AROUND 925MB VARIES FROM
AROUND 30KT IN GFS TO AROUND 40 KT IN NAM FOR SATURDAY NIGHT. AT
THIS POINT...THE GREATEST THREAT WITH ANY THUNDERSTORM WILL BE
WINDS. THE BEST FORCING OVERALL LOOKING AT THE MOISTURE FLUX IN THE
LOW LEVELS IS TO THE NORTH AND WEST IN THE AFTERNOON AND MAINLY
NORTH OF THE FORECAST REGION IN THE EVENING IN TERMS OF THE
CONVERGENCE.
FORECAST HIGH TEMPS FOR SATURDAY ARE A MAV/MET BLEND...RANGING FROM
NEAR IN THE LOWER 70S ACROSS EASTERN AREAS WITH COOLER ONSHORE FLOW
TO UPPER 70S AND LOWER 80S ACROSS WESTERN AREAS.
THE COLD FRONT MOVES THROUGH SATURDAY NIGHT...WITH A GENERAL
TIME FRAME OF 3-9Z FROM LOWER HUDSON VALLEY AND NORTHEAST NEW JERSEY
TOWARDS SOUTHEAST CONNECTICUT AND EASTERN LONG ISLAND. GUSTY WINDS
REMAIN THE THREAT THROUGH THE EVENING WITH SOME THUNDERSTORMS WITH
LOW LEVEL JET CORE MOVING ACROSS. THE UPPER LEVEL JET NEAR 250MB
WILL BE SOUTH SOUTHWESTERLY AND THE RIGHT REAR QUAD MOVES CLOSER TO
THE AREA. THE FORECAST TAKES INTO ACCOUNT THE SREF...WHICH IS CLOSER
TO THE ECMWF IN TERMS OF FRONT SPEED COMPARED TO THE GFS...WHICH IS
FASTER AND THE NAM...WHICH IS SLOWER.
SHOWERS AND THUNDERSTORMS WILL LOWER IN COVERAGE JUST BEHIND THE
FRONT LATE SATURDAY NIGHT FROM WEST TO EAST ACROSS THE REGION WITH
JET FORCING MOVING AWAY AS PARENT LOW MOVES FURTHER INTO SOUTHEAST
CANADA. USED FORECAST LOWS MORE FROM THE MET GUIDANCE LEANING MORE
TOWARDS WARMER TEMPS WITH ALL THE CLOUD COVER STILL AROUND FOR MUCH
OF THE NIGHT.
ALSO...THERE IS A HIGH RISK OF RIP CURRENTS AT THE ATLANTIC OCEAN
FACING BEACHES FOR SATURDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
ANY RESIDUAL RAIN APPEARS TO BE E OF THE CWA BY 12Z SUN. SUNNY SKIES
SHOULD EMERGE...BUT DIURNAL CU IS EXPECTED TO DEVELOP BY EARLY AFTERNOON.
A NW BREEZE CAN BE EXPECTED. TEMPS A BLEND OF THE MET/MAV.
A MID 1020S HIGH THEN BUILDS INTO THE SOUTHEASTERN CONTINENTAL
UNITED STATES MON-TUE. THIS WILL RESULT IN DRY WEATHER AND SEASONAL
TEMPS.
12Z GFS HAS TRENDED TOWARDS THE SLOWER 00/12Z ECMWF WITH THE FROPA
FOR WED. HAVE SLOWED THE FCST ACCORDINGLY. THIS KEEPS WED MAINLY
DRY. THERE IS A HINT OF A -SHRA OR SPRINKLE WITH THE WAA
PATTERN...BUT THE PROB AND COVERAGE IS TOO LOW TO INCLUDE IN THE
FCST AT THIS TIME.
CHANCE SHRA WED NIGHT INTO THU MORNING WITH THE FRONT. MOISTURE
IS LIMITED WITH THE GULF OF MEXICO SHUT OFF. TEMPS A FEW DEGREES
WARMER WED...AND REMAINS MILD OVERNIGHT WITH ONSHORE FLOW AND
CLOUD COVER.
COOL AIR MASS BEHIND THE FRONT...COULD BE FALLING OR STEADY AFTERNOON
TEMPS THU. DRY ON FRI WITH ANOTHER HIGH BUILDING IN.
&&
.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE COAST WILL GIVE WAY TO
AN APPROACHING COLD FRONT LATE IN THE DAY ON SATURDAY.
AN AREA OF MVFR STRATUS OVER NORTHEAST NJ SEEMS TO HAVE
DISSIPATED...BUT OBS AT KJFK/KEWR CONTINUE TO INDICATE A FEW MVFR
CLOUDS AT 2KFT. MVFR STRATUS ALONG THE CT COAST HAS EXPANDED AND
MOVED WEST INTO THE LOWER HUDSON VALLEY. MEANWHILE...LEADING EDGE
OF MVFR STRATUS ADVECTING IN FROM MA AND RI WILL MOVE INTO KGON
SHORTLY. AMENDMENTS MAY BE NEEDED IF BKN MVFR CIGS BECOME MORE
WIDESPREAD OR LESS WIDESPREAD THAN INDICATED.
HIGH CONFIDENCE IN SPARSE COVERAGE OF SHOWERS NORTH/WEST OF NYC
METRO SAT AFTERNOON. INCREASING CHANCE FOR SHOWERS/TSTMS AFTER 21Z
WITH APPROACH OF COLD FRONT. BEST CHANCE FOR SHOWERS/TSTMS
BETWEEN 23Z AND 02Z. HEAVY RAIN WITH BRIEF MVFR OR LOWER
CONDITIONS AND GUSTY WINDS POSSIBLE WITH THIS ACTIVITY.
OUTLOOK FOR 00Z SUNDAY THROUGH WED...
.SAT NIGHT...COLD FROPA PRECEDED BY LINE OF SHOWERS/TSTMS...WITH
MVFR OR LOWER CONDITIONS LIKELY. COLD FROPA TIMING 01Z-03Z AT NYC
METRO TERMINALS...FOLLOWED BY WIND SHIFT TO NW AND A FEW HOURS OF
GUSTY WINDS.
.SUNDAY...VFR. OCCASIONAL GUSTS INTO THE TEENS.
.SUNDAY NIGHT-WED...VFR.
&&
.MARINE...
MINOR ADJUSTMENTS MADE TO NEAR TERM GRIDS TO REFLECT LATEST TRENDS
IN OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
SUB SCA CONDITIONS WILL REMAIN ACROSS THE WATERS THROUGH AT LEAST
SATURDAY MORNING...THEN AN INCREASING SOUTHERLY FETCH WILL ALLOW
FOR BUILDING SEAS AND STRONGER WINDS INTO SATURDAY AFTERNOON.
WITH SOME UNCERTAINTY ON WAVEWATCH GUIDANCE AND HOW FAST THEY
INCREASE WITH SOUTHERLY FLOW AS WELL AS THE FREQUENCY OF THE
GUSTS...HELD OFF ON SCA FOR NOW. THESE LIKELY SCA CONDITIONS WILL
CONTINUE INTO SATURDAY NIGHT WITH FRONT MOVING ACROSS.
BRISK WNW WINDS ON SUN BEHIND THE COLD FRONT...BUT SPEEDS APPEAR TO
BE MARGINAL FOR SCA CRITERIA. SEAS ON THE OCEAN HOWEVER EXPECTED TO
BREACH THE 5FT THRESHOLD...AND WILL SUBSIDE BELOW SCA LEVEL SUN NIGHT.
HIGH PRES WILL BRING SUB SCA CONDITIONS MON-WED.
&&
.HYDROLOGY...
TOTAL QPF IS AROUND ONE TO THREE TENTHS OF AN INCH WITH LOCALLY
HIGHER AMOUNTS. THE SHOWERS AND THUNDERSTORMS WILL BE IN THE FORM
OF DISCRETE CELLS LATE SATURDAY MORNING INTO THE AFTERNOON AND IN
THE FORM OF A SQUALL LINE SATURDAY NIGHT. THE LINE SHOULD BE
RELATIVELY FAST MOVING...REALLY LIMITING THE AREAL EXTENT OF
FLOODING POTENTIAL. AT THIS POINT...THE ONLY FLOODING THREAT WOULD
BE WITH ANY REMARKABLY INTENSE CELL OR PART OF THE LINE WHICH
COULD EASILY LEAD TO SOME BRIEF MINOR POOR DRAINAGE URBAN
FLOODING. FLASH FLOOD POTENTIAL LOOKS TO BE LOW AT THE MOMENT.
WIDESPREAD SIGNIFICANT PRECIPITATION IS NOT EXPECTED SUN-FRI.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...JMC/JM/PW
NEAR TERM...MALOIT/JM/PW
SHORT TERM...JM
LONG TERM...JMC
AVIATION...JP
MARINE...JMC/MALOIT/JM/PW
HYDROLOGY...JMC/JM
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1230 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE EAST COAST WILL GIVE WAY
TO LOW PRESSURE AND AN ASSOCIATED COLD FRONT LATE SATURDAY INTO
SATURDAY NIGHT. ANOTHER HIGH WILL BRING FAIR WEATHER SUNDAY INTO
WEDNESDAY. A COLD FRONT WILL MOVE THROUGH LATE WEDNESDAY INTO
EARLY THURSDAY...FOLLOWED AGAIN BY HIGH PRESSURE BUILDING INTO
FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MINOR ADJUSTMENTS MADE TO NEAR TERM GRIDS TO REFLECT LATEST TRENDS
IN OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
FOG AND LOW CLOUDS ALREADY EVIDENT IN A FEW SPOTS...AND WILL
MAINTAIN PATCHY FOG IN THE GRIDS FOR THE OVERNIGHT. RAP INDICATING
FOG/POSSIBLE STRATUS IN TIME HEIGHTS.
LOWS WERE WEIGHTED MORE TOWARDS THE COOLER MAV GUIDANCE WITH THE
EXPECTATION OF GREATER RADIATIONAL COOLING TAKING PLACE. LOWS
FORECAST RANGE FROM UPPER 40S TO LOWER 50S FOR INLAND AND RURAL
LOCATIONS...TO THE MID 50 TO LOWER 60S ACROSS THE REMAINDER OF THE
AREA.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
THE PARENT LOW IS SIMILAR TO THE ONE ON THIS PAST TUESDAY BUT IT
IS A LITTLE FURTHER WEST. HIGH PRESSURE OFFSHORE IS NEARLY THE
SAME. THEREFORE...THERE IS LESS OF A PRESSURE GRADIENT THAN ON
TUESDAY. THIS WILL BE A KEY COMPONENT TO ASSESSING WIND AND
THEREBY SEVERE WEATHER POTENTIAL.
WINDS EARLY ON SATURDAY MORNING WILL BE INITIALLY LIGHT AND UNDER 10
KT. ACCOUNTING FOR SCATTERING OUT OF CLOUDS IN THE MORNING WITH ANY
PATCHY FOG DISSIPATING WITH DIURNAL WARMING. CAPE WILL BE INCREASING
DURING THIS TIME FRAME TO ABOUT 500-100 J/KG AS WELL AS SOME INCREASE
IN VORTICITY. SO THIS POSITIVE VORTICITY ADVECTION AND INCREASING
INSTABILITY WILL CREATE THE FIRST CHANCE OF THUNDERSTORMS. THIS
WILL BE WELL AHEAD OF THE COLD FRONT IN THE FORM OF DISCRETE
CELLS. THE MODELS ARE NOT REALLY CAPTURING THIS POTENTIAL AHEAD OF
THE FRONT AS OF YET WITH EXCEPTION OF ECMWF AND SREF WHICH SHOWS
AT LEAST A FEW HUNDREDTHS OF AN INCH INTO FAR WESTERN PORTIONS OF
THE AREA BY 18Z SAT. THE 12Z RUN OF THE GFS ALSO HAS PROGRESSED
FARTHER EAST WITH ITS QPF FIELD COMPARED TO ITS PREVIOUS RUN IN
BETWEEN 12-18Z. THE ONE LIMITING FACTOR WILL BE THE MOISTURE AS
DEWPOINTS WILL STILL BE IN THE LOWER 60S EARLY SATURDAY MORNING
BUT WITH A STEADY INCREASE THEREAFTER FROM INCREASING LOW LEVEL
SOUTH TO SOUTHWEST FLOW...THIS WILL AUGMENT THETA-E ADVECTION IN
THE LOW LEVELS AND THE RATE SPIKES INITIALLY BETWEEN 12 AND 15Z
WITH AT LEAST A 7K/3HR INCREASE FOR WESTERN LOCATIONS AT 925MB.
THE BEST POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL SIMILAR THE
925MB THETA-E PROGRESSION OF AT LEAST 330K.
TAKING THIS INTO ACCOUNT...THE LIMITING MOISTURE FACTOR WILL KEEP
POPS LOW AT SLIGHT CHANCE AND GRADUALLY INCREASING CHANCES FROM WEST
TO EAST MID MORNING ONWARD AS THE TROUGH PUSHES CLOSER TO THE
REGION.
THE CAPE REALLY DROPS OFF ACROSS EASTERN COASTAL SECTIONS SO THEY
WILL HAVE MOST LIKELY DRY CONDITIONS WITH JUST A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON. WOULD NOT BE
SURPRISED IF THE WHOLE DAY IS DRY FOR EASTERN SECTIONS.
THE CAPE INCREASES TO AROUND 1000-1500 J/KG FOR THE LOWER HUDSON
VALLEY AND INTERIOR NORTHEAST NEW JERSEY AND BETWEEN 500-1000 J/KG
EAST ACROSS THE REST OF NORTHEAST NEW JERSEY...NEW YORK
CITY...WESTERN LONG ISLAND AND SOUTHWEST CONNECTICUT. THESE 500-1000
J/KG CAPE VALUES SPREAD MORE ACROSS LONG ISLAND SATURDAY NIGHT.
THE 0-6KM BULK SHEAR WILL BE MAINLY BETWEEN 30-40 KT AND THIS
COMBINED WITH THE CAPE WILL ALLOW FOR SOME THUNDERSTORMS TO BE
STRONG TO POSSIBLY SEVERE. LOW LEVEL JET AROUND 925MB VARIES FROM
AROUND 30KT IN GFS TO AROUND 40 KT IN NAM FOR SATURDAY NIGHT. AT
THIS POINT...THE GREATEST THREAT WITH ANY THUNDERSTORM WILL BE
WINDS. THE BEST FORCING OVERALL LOOKING AT THE MOISTURE FLUX IN THE
LOW LEVELS IS TO THE NORTH AND WEST IN THE AFTERNOON AND MAINLY
NORTH OF THE FORECAST REGION IN THE EVENING IN TERMS OF THE
CONVERGENCE.
FORECAST HIGH TEMPS FOR SATURDAY ARE A MAV/MET BLEND...RANGING FROM
NEAR IN THE LOWER 70S ACROSS EASTERN AREAS WITH COOLER ONSHORE FLOW
TO UPPER 70S AND LOWER 80S ACROSS WESTERN AREAS.
THE COLD FRONT MOVES THROUGH SATURDAY NIGHT...WITH A GENERAL
TIME FRAME OF 3-9Z FROM LOWER HUDSON VALLEY AND NORTHEAST NEW JERSEY
TOWARDS SOUTHEAST CONNECTICUT AND EASTERN LONG ISLAND. GUSTY WINDS
REMAIN THE THREAT THROUGH THE EVENING WITH SOME THUNDERSTORMS WITH
LOW LEVEL JET CORE MOVING ACROSS. THE UPPER LEVEL JET NEAR 250MB
WILL BE SOUTH SOUTHWESTERLY AND THE RIGHT REAR QUAD MOVES CLOSER TO
THE AREA. THE FORECAST TAKES INTO ACCOUNT THE SREF...WHICH IS CLOSER
TO THE ECMWF IN TERMS OF FRONT SPEED COMPARED TO THE GFS...WHICH IS
FASTER AND THE NAM...WHICH IS SLOWER.
SHOWERS AND THUNDERSTORMS WILL LOWER IN COVERAGE JUST BEHIND THE
FRONT LATE SATURDAY NIGHT FROM WEST TO EAST ACROSS THE REGION WITH
JET FORCING MOVING AWAY AS PARENT LOW MOVES FURTHER INTO SOUTHEAST
CANADA. USED FORECAST LOWS MORE FROM THE MET GUIDANCE LEANING MORE
TOWARDS WARMER TEMPS WITH ALL THE CLOUD COVER STILL AROUND FOR MUCH
OF THE NIGHT.
ALSO...THERE IS A HIGH RISK OF RIP CURRENTS AT THE ATLANTIC OCEAN
FACING BEACHES FOR SATURDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
ANY RESIDUAL RAIN APPEARS TO BE E OF THE CWA BY 12Z SUN. SUNNY SKIES
SHOULD EMERGE...BUT DIURNAL CU IS EXPECTED TO DEVELOP BY EARLY AFTERNOON.
A NW BREEZE CAN BE EXPECTED. TEMPS A BLEND OF THE MET/MAV.
A MID 1020S HIGH THEN BUILDS INTO THE SOUTHEASTERN CONTINENTAL
UNITED STATES MON-TUE. THIS WILL RESULT IN DRY WEATHER AND SEASONAL
TEMPS.
12Z GFS HAS TRENDED TOWARDS THE SLOWER 00/12Z ECMWF WITH THE FROPA
FOR WED. HAVE SLOWED THE FCST ACCORDINGLY. THIS KEEPS WED MAINLY
DRY. THERE IS A HINT OF A -SHRA OR SPRINKLE WITH THE WAA
PATTERN...BUT THE PROB AND COVERAGE IS TOO LOW TO INCLUDE IN THE
FCST AT THIS TIME.
CHANCE SHRA WED NIGHT INTO THU MORNING WITH THE FRONT. MOISTURE
IS LIMITED WITH THE GULF OF MEXICO SHUT OFF. TEMPS A FEW DEGREES
WARMER WED...AND REMAINS MILD OVERNIGHT WITH ONSHORE FLOW AND
CLOUD COVER.
COOL AIR MASS BEHIND THE FRONT...COULD BE FALLING OR STEADY AFTERNOON
TEMPS THU. DRY ON FRI WITH ANOTHER HIGH BUILDING IN.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
A WEAKENING HIGH PRESSURE RIDGE ALONG THE COAST WILL GIVE WAY TO
AN APPROACHING COLD FRONT LATE IN THE DAY ON SATURDAY.
SATELLITE SHOWS LOW STRATUS BEGINNING TO FORM ALONG THE CT
COAST...AND SHOULD EXPAND IN AREAL COVERAGE. OBS AT KJFK/KEWR ALSO
INDICATE A FEW LOW CLOUDS BEGINNING TO DEVELOP THERE AS WELL.
HELD THE COURSE FROM 00Z TAF...BUT TACTICAL AMENDMENTS MAY BE
NEEDED IF BKN LOW CIGS BECOME MORE WIDESPREAD THAN INDICATED.
CIGS/VSBY EXPECTED TO IMPROVE BY MID TO LATE MORNING SAT...WITH
GUSTY S WINDS DEVELOPING...MAXING OUT IN THE AFTERNOON AT 14-16
KT WITH GUSTS INTO THE LOWER 20S ACROSS THE NYC METRO TERMINALS.
HIGH CONFIDENCE IN SPARSE COVERAGE OF SHOWERS NORTH/WEST OF NYC
METRO SAT AFTERNOON. INCREASING CHANCE FOR SHOWERS/TSTMS AFTER 21Z
WITH APPROACH OF COLD FRONT. HEAVY RAIN WITH BRIEF MVFR OR LOWER
CONDITIONS AND GUSTY WINDS POSSIBLE WITH THIS ACTIVITY.
OUTLOOK FOR 00Z SUNDAY THROUGH WED...
.SAT NIGHT...COLD FROPA PRECEDED BY LINE OF SHOWERS/TSTMS...WITH
MVFR OR LOWER CONDITIONS LIKELY. COLD FROPA TIMING 01Z-03Z AT NYC
METRO TERMINALS...FOLLOWED BY WIND SHIFT TO NW AND A FEW HOURS OF
GUSTY WINDS.
.SUNDAY...VFR. OCCASIONAL GUSTS INTO THE TEENS.
.SUNDAY NIGHT-WED...VFR.
&&
.MARINE...
MINOR ADJUSTMENTS MADE TO NEAR TERM GRIDS TO REFLECT LATEST TRENDS
IN OBSERVATIONS AND GUIDANCE. FORECAST APPEARS ON TRACK.
SUB SCA CONDITIONS WILL REMAIN ACROSS THE WATERS THROUGH AT LEAST
SATURDAY MORNING...THEN AN INCREASING SOUTHERLY FETCH WILL ALLOW
FOR BUILDING SEAS AND STRONGER WINDS INTO SATURDAY AFTERNOON.
WITH SOME UNCERTAINTY ON WAVEWATCH GUIDANCE AND HOW FAST THEY
INCREASE WITH SOUTHERLY FLOW AS WELL AS THE FREQUENCY OF THE
GUSTS...HELD OFF ON SCA FOR NOW. THESE LIKELY SCA CONDITIONS WILL
CONTINUE INTO SATURDAY NIGHT WITH FRONT MOVING ACROSS.
BRISK WNW WINDS ON SUN BEHIND THE COLD FRONT...BUT SPEEDS APPEAR TO
BE MARGINAL FOR SCA CRITERIA. SEAS ON THE OCEAN HOWEVER EXPECTED TO
BREACH THE 5FT THRESHOLD...AND WILL SUBSIDE BELOW SCA LEVEL SUN NIGHT.
HIGH PRES WILL BRING SUB SCA CONDITIONS MON-WED.
&&
.HYDROLOGY...
TOTAL QPF IS AROUND ONE TO THREE TENTHS OF AN INCH WITH LOCALLY
HIGHER AMOUNTS. THE SHOWERS AND THUNDERSTORMS WILL BE IN THE FORM
OF DISCRETE CELLS LATE SATURDAY MORNING INTO THE AFTERNOON AND IN
THE FORM OF A SQUALL LINE SATURDAY NIGHT. THE LINE SHOULD BE
RELATIVELY FAST MOVING...REALLY LIMITING THE AREAL EXTENT OF
FLOODING POTENTIAL. AT THIS POINT...THE ONLY FLOODING THREAT WOULD
BE WITH ANY REMARKABLY INTENSE CELL OR PART OF THE LINE WHICH
COULD EASILY LEAD TO SOME BRIEF MINOR POOR DRAINAGE URBAN
FLOODING. FLASH FLOOD POTENTIAL LOOKS TO BE LOW AT THE MOMENT.
WIDESPREAD SIGNIFICANT PRECIPITATION IS NOT EXPECTED SUN-FRI.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...PW/JM/JMC
NEAR TERM...MALOIT/PW/JM
SHORT TERM...JM
LONG TERM...JMC
AVIATION...GOODMAN
MARINE...MALOIT/PW/JM/JMC
HYDROLOGY...JM/JMC
AREA FORECAST DISCUSSION
NWS MIAMI FL
144 AM EDT SAT SEP 22 2012
.AVIATION...
ISOLATED SHRAS/TSRAS CONTINUE TO STREAM TO THE NORTH MAINLY ALONG
THE GULF AND ATLANTIC COASTAL WATERS THIS MORNING. A DEEP MOISTURE
FIELD ALONG WITH A PASSING SURFACE TROUGH JUST WEST OF THE
FLORIDA KEYS WILL KEEP SHRAS ACROSS MUCH OF THE AREA THROUGH THE
EARLY MORNING HOURS. KEPT VCSH AT ALL TERMINALS THROUGH THE
MORNING FOLLOWED BY VCTS AS A WEAK MID LEVEL SHORTWAVE SWEEPS
ACROSS SOUTH FLORIDA DURING THE PEAK HEATING HOURS FURTHER
ENHANCING SCATTERED TO WIDESPREAD TSRA DEVELOPMENT.
&&
.PREV DISCUSSION... /ISSUED 1009 PM EDT FRI SEP 21 2012/
UPDATE...
LATEST RADAR RETURNS AND SATELLITE IMAGERY INDICATE MOSTLY CLOUDY
SKIES ACROSS THE REGION AND WIDELY DISPERSED SHOWERS AND ISOLATED
THUNDERSTORMS...WITH MOST OF THE SHOWERS REMAINING ACROSS THE
WESTERN HALF OF THE PENINSULA AND GULF WATERS. ALTHOUGH THERE IS
SPARSE ACTIVITY ACROSS THE ATLANTIC WATERS AND THE EASTERN HALF OF
THE PENINSULA...REDEVELOPMENT OF CONVECTION IS POSSIBLE ACROSS THE CWA.
GIVEN THE MID TO UPPER LEVEL TROUGH OVER THE GULF WITH RECENT
GUIDANCE INDICATING EMBEDDED SHORT WAVES POSSIBLE IN THE PROXIMITY
OF SOUTH FLORIDA...NEW CONVECTION IS POSSIBLE THE REMAINING
EVENING HOURS AND OVER NIGHT. IN ADDITION THE 00Z SOUNDING
INDICATED LINGERING INSTABILITY AND LOW LEVEL LAPSE RATES THAT
INDICATE THE POTENTIAL FOR ADDITIONAL CONVECTION. THEREFORE
MAINTAINING A CHANCE OF SHOWERS AND THUNDERSTORMS CWA WIDE THIS
EVENING AND OVER NIGHT.
60
PREV DISCUSSION... /ISSUED 738 PM EDT FRI SEP 21 2012/
AVIATION...LIGHT RAIN CONTINUES TO IMPACT KAPF AND KPBI BUT WITH
VFR CONDITIONS. THE LIGHT RAIN WILL TAPER OFF THERE OVER THE NEXT
1-2 HR. THEN IT IS A CHALLENGING FORECAST AS TO WHAT TRANSPIRES
OVERNIGHT. HAVE MAINTAINED VCSH THEN VCTS LATE TONIGHT FOR THE EAST
COAST AS CONVECTION COULD RE-DEVELOP OVER THE ATLANTIC AND MOVE
ONSHORE. IT COULD BE A VERY WET DAY ON SATURDAY WITH POTENTIAL FOR
NUMEROUS SHRA/TSRA, SOME WITH HEAVY RAINS. HAVE PLACED PROB30 OF
MVFR CONDITIONS ALL EAST COAST SITES FROM 14-20Z SAT...AND WE CAN
TREND THIS WORSE AS TIME APPROACHES. IFR AND LIFR IS A POSSIBILITY
AT TIMES ON SATURDAY, ESPECIALLY EAST COAST TERMINALS. KAPF HAS A
LESSER CHANCE OF IMPACTS, SO MAINTAINED VCTS THERE FOR SATURDAY AT
THIS TIME. /GREGORIA
PREV DISCUSSION... /ISSUED 242 PM EDT FRI SEP 21 2012/
SHORT TERM...(TONIGHT-SUNDAY NIGHT)
THE LATEST RUC13 400 MB ANALYSIS AND WATER VAPOR LOOP SHOWED THE
LOCAL AREA UNDER MOIST SOUTHWEST UPPER FLOW AHEAD OF A LARGE SCALE
UPPER TROUGH CENTERED OVER MUCH OF THE COUNTRY. SEVERAL WEAK
PIECES OF ENERGY TRANSLATING NORTHEAST OVER THE STATE WITHIN THIS
SW UPPER FLOW COMBINED WITH THE OLD FRONTAL BOUNDARY AT THE
SURFACE THAT IS FORECAST TO SLOWLY SHIFT SOUTH INTO THE LOCAL AREA
THIS WEEKEND WILL KEEP THE RAIN CHANCES IN THE FORECAST. FOR THIS
EVENING...THE LATEST HRRR GUIDANCE INDICATES SCATTERED STORMS
SETTING UP FROM NAPLES TO THE LAKE REGION...WHICH IS VERY SIMILAR
TO YESTERDAY AFTERNOON/EVENING. ON SATURDAY...THE LATEST GFS
SOLUTION INDICATES A SURFACE WAVE DEVELOPING ALONG THIS BOUNDARY
AS A WEAK VORT MAX LIFTS NORTHEAST OVER THE AREA THROUGH THE DAY.
THIS COMBINED WITH PLENTY OF DEEP LAYER MOISTURE COULD LEAD TO AN
ENHANCED PERIOD OF RAINFALL TOMORROW ONCE AGAIN TOMORROW. IF THIS
DOES OCCUR...WEAK LOW LEVEL FLOW COULD TRANSLATE TO FLOODING
CONCERNS DEPENDING ON WHERE THE BULK OF THE ACTIVITY BECOMES
CONCENTRATED.
SATURDAY NIGHT THROUGH SUNDAY NIGHT...WHATS LEFT OF THE PREVIOUSLY
DISCUSSED BOUNDARY OR DEEP LAYER MOISTURE AXIS IN PLACE ACROSS S FL
IS FORECAST TO SLIGHTLY SHIFT FARTHER SOUTH AS ANOTHER REINFORCING
COLD FRONT SURGES SOUTH INTO THE REGION AND THE LARGE SCALE UPPER
TROUGH BEGINS TO SHIFT EAST. THE GFS APPEARS TO BE SLIGHTLY FASTER
THAN THE ECMWF AND NAM SOLUTIONS AND BEGINS TO INTRODUCE SOME DRIER
AIR AROUND THE LAKE REGION COME SUNDAY NIGHT INTO MONDAY. 85/AG
LONG TERM...(MONDAY-THURSDAY)
THE UPPER TROUGH BEGINS TO SHIFT SLOWLY EAST AS THE UPPER RIDGE
OVER THE ROCKIES BEGINS TO BREAK DOWN AS ANOTHER MID LEVEL TROUGH
MOVES FROM THE PACIFIC NORTHWEST INTO THE ROCKIES. SOME SLIGHT
DRYING /DECREASE MAY OCCUR INITIALLY AS DRIER AIR FILTERS IN THE
THE NW BUT THE MODELS HINT AT AN UPPER LOW DEVELOPING OVER THE
GULF AND MOVING NE ACROSS THE FLA PENINSULA IN THE LATTER PERIODS.
WILL STAY CLOSE TO EXTENDED GUIDANCE AND SEE WHAT DEVELOPS. JR
MARINE...
LIGHT EASTERLY WINDS WILL PERSIST THROUGH THE WEEKEND
WITH SEAS REMAINING AROUND NORMAL. A STALLED FRONTAL BOUNDARY
COMBINED WITH AN UPPER TROUGH OF LOW PRESSURE WILL KEEP THE
RAINFALL CHANCES ELEVATED THROUGH THE WEEKEND. WINDS AND SEAS CAN
LOCALLY BECOME HIGHER IN AND AROUND ANY HEAVY SHOWERS OR STORMS.
FIRE WEATHER...
NO CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 84 77 87 / 60 40 40 30
FORT LAUDERDALE 74 84 75 88 / 60 40 40 40
MIAMI 74 86 75 89 / 60 40 50 40
NAPLES 75 84 75 91 / 50 30 30 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...15/JR
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
209 AM CDT SAT SEP 22 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
.DISCUSSION...
348 PM CDT
COOL THROUGH THE WEEKEND THEN TEMPERATURES MODERATE FIRST PART OF
NEXT WEEK. A SHORT BREAK IN THREAT OF RAIN THIS EVENING THEN
CHANCES RETURN OVERNIGHT THROUGH SAT MORNING.
MULTIPLE MINOR SHORT WAVES IN THE UPPER FLOW TURNING FROM SSE TO
SE AS THEY CROSS THE UPPER MIDWEST AND THEN SE TO ESE AS THEY
ROTATE ACROSS THE MID MS VALLEY AND THE WESTERN GREAT LAKES INTO
THE BASE OF THE UPPER TROUGH THE REST OF TODAY AND THIS EVENING.
FURTHER UPSTREAM OVER SOUTHERN MANITOBA IS A STRONGER SHORT WAVE
PROGGED TO REACH SOUTHERN WI BY 12Z SAT. AS THIS DISTURBANCE
APPROACHES LATE TONIGHT A CHANCE OF RAIN RETURNS
OVERNIGHT...ENDING MIDDAY WITH THIS SHORT WAVE TROUGH PROGGED TO
CONTINUE ON TO NORTHERN IND BY 18Z SAT. HIGHEST CHANCES WILL BE
ACROSS THE NE 1/2 OF THE FORECAST AREA...ALONG AND N OF THE
PROJECTED PATH OF THE VORT MAX.
IN THE WAKE OF THE SHORT WAVE/WAVES MOVING ACROSS THE AREA TODAY
WEAK LOW LEVEL COLD AIR ADVECTION TO TAKE PLACE. THIS...COMBINED
WITH EXPECTED SHOWERS AND EXTENSIVE CLOUDINESS...WILL KEEP
TEMPERATURES DURING SAT LIMITED TO THE UPPER 50S AND LOWER 60S.
WITH THE PASSAGE OF THE STRONGER SHORT WAVE DURING SAT MORNING
STRONGER COLD AIR ADVECTION TO TAKE PLACE WITH 850HPA
TEMPERATURES DROPPING TO AROUND 0C FOR THE AFTERNOON. DESPITE THE
COLD AIR ADVECTION SURFACE HEATING IS EXPECTED TO MITIGATE THE
COOLING AS CLOUDS CLEAR DURING THE DAY IN THE WAKE OF THE SHORT
WAVE.
A HIGH PRESSURE RIDGE IS TO BE BUILDING FROM THE NORTHERN PLAINS
ACROSS THE MO RIVER VALLEY DURING THE DAY SAT AND THE UPPER AND
MID MS VALLEY AND LOWER OH VALLEY DURING SAT NIGHT. CLEAR
SKIES...DEW POINTS IN THE MID 20S TO LOWER 30S...AND LACK OF
BOUNDARY LAYER MIXING AS SURFACE WINDS BECOME NIL ARE EXPECTED TO
LEAD TO SAT NIGHT LOWS IN THE LOWER AND MID 30S ACROSS MUCH OF
THE LOCAL FORECAST AREA. FROST A GOOD POSSIBILITY ACROSS THE W
AND SW PORTIONS OF THE FORECAST AREA...CLOSEST TO THE SURFACE
RIDGE AXIS...OVERNIGHT SAT AND EARLY SUN MORNING.
YET ANOTHER SHORT WAVE IS SHOWN BY MODELS DROPPING OVER THE UPPER
MIDWEST AND THE WESTERN GREAT LAKES DURING SUN. HOWEVER...WITH A
VERY DRY AIR MASS IN PLACE POPS ONLY IN THE SINGLE DIGITS. EVEN
CLOUDS WILL BE HARD TO COME BY WITH JUST SOME CIRRUS ASSOCIATED
WITH THE JET MAX MOVING OVERHEAD. WITH THE UPPER TROUGH
BROADENING OVER THE REGION AND THE CENTER OF THE CENTER OF THE
LARGE SCALE UPPER CYCLONE REESTABLISHING ITSELF OVER SOUTHERN
HUDSON BAY AND NW QUEBEC BY MON MORNING THE MID LATITUDE UPPER
FLOW BACKS TO OUT OF THE WNW. WITH THE UPPER LOW FURTHER NORTH
DISTURBANCES ROTATING AROUND IT WILL TRACK OVER THE NORTH WOODS
AND THE NORTHERN GREAT LAKES KEEPING CHANCES OF PRECIPITATION LOW
THROUGH MON NIGHT.
HOWEVER...A COLD FRONT IS PROGGED TO SLIP SE ACROSS THE LOCAL
AREA TUE AND TUE NIGHT BEFORE BECOMING STATIONARY FROM NE MO
ACROSS CENTRAL IL TO NORTHERN IND BY WED MORNING. INCREASING FLOW
FROM THE CENTRAL PLAINS ENE ACROSS THE MID MS VALLEY WILL RESULT
IN INCREASING WARM AIR ADVECTION AS WELL AS MID AND LOWER LEVEL
MOISTURE TRANSPORT INTO THE AREA WITH CHANCES OF SHOWERS AND
THUNDERSTORMS...MAINLY FOR THE N 1/2 TO 3/4 OF THE LOCAL FORECAST
AREA TUE THROUGH WED BEFORE A STRONG SHORT WAVE DROPPING ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES PUSHES THE SURFACE FRONT
FURTHER TO THE S AND ANOTHER LARGE SURFACE ANTICYCLONE BUILDS OVER
THE UPPER MIDWEST AND THE GREAT LAKES DURING WED AND WED NIGHT.
WED NIGHT THROUGH FRI WILL HAVE LOW POPS AS THE HIGH PRESSURE WILL
DOMINATE THE WEATHER OVER THE REGION...CONTINUING TO FEED COOL DRY
AIR ACROSS THE AREA.
TRS
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODS OF SHOWERS THIS MORNING...WITH PATCHY MVFR CONDITIONS
POSSIBLE.
* STRONG NORTHWEST WINDS GUSTING UP TO 30 KTS...ESPECIALLY THIS
MORNING FOLLOWING THE FRONTAL PASSAGE.
KJB
//DISCUSSION...UPDATED 06Z...
THE MAIN FORECAST CONCERNS TODAY WILL BE THE ONSET OF STRONG
NORTHWEST WINDS THIS MORNING IN THE WAKE OF STRONG COLD FRONTAL
PASSAGE.
CURRENTLY THIS STRONG COLD FRONT IS PUSHING ACROSS FAR SOUTHEASTERN
MINNESOTA AND FAR NORTHERN IOWA. THE FRONT SHOULD ARRIVE AT KRFD
AROUND DAYBREAK AND AROUND 14 UTC AT THE NORTHEASTERN ILLINOIS
SITES. DIRECTLY IN THE WAKE OF THIS FRONT STRONG COLD AIR ADVECTION
AND RAPID PRESSURE RISES HAVE BEEN RESULTING IN WIND GUSTS UP TO
AROUND 30 KT ACROSS MINNESOTA. I EXPECT THESE TYPES OF GUSTS TO BE
REALIZED HERE AS WELL FOR AN HOUR OR TWO FOLLOWING THE FRONTAL
PASSAGE THIS MORNING. THE WINDS SHOULD WEAKEN SOME THIS
AFTERNOON...BUT EXPECT THEM TO REMAIN GUSTY AROUND 20 TO 25 KT AT
TIMES.
THERE WILL ALSO BE PERIODS OF SHOWERS THROUGH THE MORNING HOURS. AN
AREA OF LIGHT SHOWERS IS CURRENTLY APPROACHING THE TERMINALS. THIS
ACTIVITY WILL BE A QUICK HIT...AND MOVE OUT SHORTLY AFTER 07 UTC.
HOWEVER...ADDITIONAL ACTIVITY WILL LIKELY DEVELOP TO OUR NORTHWEST
OVERNIGHT AND SHOULD AFFECT THE AREA THROUGH THE MORNING HOURS AS A
STRONG MID LEVEL ATMOSPHERIC DISTURBANCE SHIFTS SOUTHEASTWARD ACROSS
NORTHERN ILLINOIS. IT ALSO APPEARS THERE WILL BE SOME LOWER CIGS
THROUGH THE MORNING HOURS FOLLOWING THE FRONTAL PASSAGE.
HOWEVER...IT APPEARS THE CIGS WILL REMAIN ABOVE 1500 FEET
AGL...AND ANY MVFR CIGS SHOULD IMPROVE DURING THE AFTERNOON.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM-HIGH CONFIDENCE IN WIND TRENDS TONIGHT.
* MEDIUM CONFIDENCE IN TIMING OF PRECIP/CIGS THROUGH PERIOD.
* HIGH CONFIDENCE IN WIND TRENDS SATURDAY.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR. DIMINISHING WEST-NORTHWEST WINDS.
MONDAY...VFR.
TUESDAY...VFR. CHC SHRA.
WEDNESDAY...VFR.
THURSDAY...VFR.
RATZER
&&
.MARINE...
207 AM CDT
A STRONG COLD FRONT WILL PUSH ACROSS LAKE MICHIGAN THIS MORNING.
STRONG NORTHWEST WINDS UP TO 35 KT GALES ARE EXPECTED LATER TODAY
INTO THIS EVENING ACROSS THE NORTH END OF THE LAKE AS THE PRESSURE
GRADIENT INCREASES IN RESPONSE TO THE RAPID CONSOLIDATION AND
DEEPENING OF LOW PRESSURE ACROSS WESTERN QUEBEC. ON THE SOUTHERN
SECTIONS OF THE LAKE THE WINDS WILL NOT BE MUCH WEAKER. THERE COULD
BE A SHORT PERIOD OF NEAR GALE FORCE WINDS EARLY THIS MORNING ACROSS
THE FAR SOUTHERN END OF THE LAKE AS THE COLD FRONT PUSHES THROUGH.
OTHERWISE EXPECT NORTHWESTERLY WINDS AROUND 30 KT TODAY INTO
TONIGHT. WATERSPOUTS ARE ALSO STILL POSSIBLE THROUGH THE WEEKEND AS
THE COLD AIRMASS OVER THE LAKE WILL CONTINUE TO PRODUCE UNSTABLE
CONDITIONS.
THE WINDS ACROSS THE LAKE SHOULD EASE SOME ON SUNDAY. HOWEVER...THIS
LOOKS TO BE SHORT LIVED. BY MONDAY THE WINDS SHOULD TURN
SOUTHWESTERLY AND QUICKLY INCREASE AS SURFACE HIGH PRESSURE PUSHES
SOUTH ACROSS THE OHIO VALLEY AND ANOTHER STRONG TROUGH OF LOW
PRESSURE DROPS SOUTH ACROSS THE UPPER GREAT LAKES REGION. THIS LOOKS
TO SET UP A VERY IMPRESSIVE PRESSURE GRADIENT ACROSS THE LAKE ON
MONDAY INTO MONDAY EVENING AHEAD OF ANOTHER COLD FRONT. IT APPEARS
THE GALE FORCE WINDS ARE A VERY GOOD POSSIBILITY WITH THIS
SETUP...ESPECIALLY ACROSS THE NORTHERN HALF OF THE LAKE ON MONDAY
AND MONDAY EVENING. A COLD FRONT WILL FINALLY PUSH DOWN THE LAKE ON
TUESDAY BRINGING AN END TO THE STRONG SOUTHWESTERLY WINDS.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1246 AM CDT SAT SEP 22 2012
.MESOSCALE DISCUSSION...
300 PM CDT
CONTINUE TO MONITOR POTENTIAL FOR A COUPLE SEVERE STORMS ACROSS
THE SOUTHERN FORECAST AREA...PRIMARILY ALONG AND SOUTH OF U.S.
HIGHWAY 24.
STRONG WELL-ALIGNED UPPER AND MID LEVEL NORTHWESTERLY JETS
CONTINUE TO PROGRESS SOUTHEAST FROM IA WITH AN
ELONGATED SHORT WAVE...POSSIBLY TWO...IMPULSE FROM SOUTHERN MN
INTO SOUTHEAST IA. LATEST HAND SURFACE ANALYSIS DEPICTS A 1005 MB
SURFACE LOW NEAR PITTSFIELD IN WEST CENTRAL IL WITH STRONG
PRESSURE FALLS OF ALMOST 5 MB/3 HR IN ADVANCE. THIS IS WELL
ALIGNED WITH ROBUST LOW-LEVEL TD ADVECTION /8-14F CLIMBS PER
HOUR/ INTO THE MID TO UPPER 50S FROM SPI/TAZ SOUTHEASTWARD ACROSS
THE ILX CWA. THIS AREA HIGHLIGHTS WHERE THE DEVELOPING SURFACE
WARM FRONT IS AND LIKELY NEAR THE NORTHERN EXTENT OF ANY SURFACE-
BASED UPDRAFT POTENTIAL. DEW POINTS REMAIN LOW NORTH OF THIS
AREA...INCLUDING IN THE SOUTHERN FORECAST AREA WHERE NAMELY MID
40S PREVAIL ALONG WITH MORE OF AN EASTERLY WIND COMPONENT. WHILE
THE MOISTENING BOUNDARY LAYER IS MOVING NORTH QUICKLY IN ADVANCE
OF THE LOW...AT THIS TIME IT DOES NOT LOOK TO MAKE IT ALL THE WAY
TO THE SOUTHERN FORECAST AREA. SO THE MAIN CONCERNS REMAIN FOR
ELEVATED STORMS.
MID-LEVEL FLOW ANALYZED BY UPSTREAM PROFILES AND THE RAP MODEL OF
OVER 50 KT IS CONTRIBUTING TO DEEP LAYER SHEAR AT OR IN EXCESS OF
60 KT INTO CENTRAL IL. STRENGTHENING SOUTHERLY 850 MB FLOW AND
MOISTURE TRANSPORT AHEAD OF THE DEVELOPING LOW PRESSURE IS
FURTHERING THE CROSSOVER COMPONENT NEAR THE INTERSTATE 74 CORRIDOR
AND UP TO THE SOUTHERN CWA. INSTABILITY IS SOMEWHAT MEAGER...BUT
LIKELY UNDERDONE BY MOST GUIDANCE GIVEN THE CONVECTIVE
TRENDS...AND COULD BE NEAR 500 J/KG. TOGETHER THIS COULD SUPPORT
BRIEF ELEVATED SUPERCELLS OR POSSIBLY A SMALL ARC/CLUSTER OF
STORMS TRACKING ACROSS THE FAR SOUTHERN FORECAST AREA BETWEEN 4
AND 7 PM...CAPABLE OF MAINLY A HAIL THREAT.
MTF
&&
.DISCUSSION...
348 PM CDT
COOL THROUGH THE WEEKEND THEN TEMPERATURES MODERATE FIRST PART OF
NEXT WEEK. A SHORT BREAK IN THREAT OF RAIN THIS EVENING THEN
CHANCES RETURN OVERNIGHT THROUGH SAT MORNING.
MULTIPLE MINOR SHORT WAVES IN THE UPPER FLOW TURNING FROM SSE TO
SE AS THEY CROSS THE UPPER MIDWEST AND THEN SE TO ESE AS THEY
ROTATE ACROSS THE MID MS VALLEY AND THE WESTERN GREAT LAKES INTO
THE BASE OF THE UPPER TROUGH THE REST OF TODAY AND THIS EVENING.
FURTHER UPSTREAM OVER SOUTHERN MANITOBA IS A STRONGER SHORT WAVE
PROGGED TO REACH SOUTHERN WI BY 12Z SAT. AS THIS DISTURBANCE
APPROACHES LATE TONIGHT A CHANCE OF RAIN RETURNS
OVERNIGHT...ENDING MIDDAY WITH THIS SHORT WAVE TROUGH PROGGED TO
CONTINUE ON TO NORTHERN IND BY 18Z SAT. HIGHEST CHANCES WILL BE
ACROSS THE NE 1/2 OF THE FORECAST AREA...ALONG AND N OF THE
PROJECTED PATH OF THE VORT MAX.
IN THE WAKE OF THE SHORT WAVE/WAVES MOVING ACROSS THE AREA TODAY
WEAK LOW LEVEL COLD AIR ADVECTION TO TAKE PLACE. THIS...COMBINED
WITH EXPECTED SHOWERS AND EXTENSIVE CLOUDINESS...WILL KEEP
TEMPERATURES DURING SAT LIMITED TO THE UPPER 50S AND LOWER 60S.
WITH THE PASSAGE OF THE STRONGER SHORT WAVE DURING SAT MORNING
STRONGER COLD AIR ADVECTION TO TAKE PLACE WITH 850HPA
TEMPERATURES DROPPING TO AROUND 0C FOR THE AFTERNOON. DESPITE THE
COLD AIR ADVECTION SURFACE HEATING IS EXPECTED TO MITIGATE THE
COOLING AS CLOUDS CLEAR DURING THE DAY IN THE WAKE OF THE SHORT
WAVE.
A HIGH PRESSURE RIDGE IS TO BE BUILDING FROM THE NORTHERN PLAINS
ACROSS THE MO RIVER VALLEY DURING THE DAY SAT AND THE UPPER AND
MID MS VALLEY AND LOWER OH VALLEY DURING SAT NIGHT. CLEAR
SKIES...DEW POINTS IN THE MID 20S TO LOWER 30S...AND LACK OF
BOUNDARY LAYER MIXING AS SURFACE WINDS BECOME NIL ARE EXPECTED TO
LEAD TO SAT NIGHT LOWS IN THE LOWER AND MID 30S ACROSS MUCH OF
THE LOCAL FORECAST AREA. FROST A GOOD POSSIBILITY ACROSS THE W
AND SW PORTIONS OF THE FORECAST AREA...CLOSEST TO THE SURFACE
RIDGE AXIS...OVERNIGHT SAT AND EARLY SUN MORNING.
YET ANOTHER SHORT WAVE IS SHOWN BY MODELS DROPPING OVER THE UPPER
MIDWEST AND THE WESTERN GREAT LAKES DURING SUN. HOWEVER...WITH A
VERY DRY AIR MASS IN PLACE POPS ONLY IN THE SINGLE DIGITS. EVEN
CLOUDS WILL BE HARD TO COME BY WITH JUST SOME CIRRUS ASSOCIATED
WITH THE JET MAX MOVING OVERHEAD. WITH THE UPPER TROUGH
BROADENING OVER THE REGION AND THE CENTER OF THE CENTER OF THE
LARGE SCALE UPPER CYCLONE REESTABLISHING ITSELF OVER SOUTHERN
HUDSON BAY AND NW QUEBEC BY MON MORNING THE MID LATITUDE UPPER
FLOW BACKS TO OUT OF THE WNW. WITH THE UPPER LOW FURTHER NORTH
DISTURBANCES ROTATING AROUND IT WILL TRACK OVER THE NORTH WOODS
AND THE NORTHERN GREAT LAKES KEEPING CHANCES OF PRECIPITATION LOW
THROUGH MON NIGHT.
HOWEVER...A COLD FRONT IS PROGGED TO SLIP SE ACROSS THE LOCAL
AREA TUE AND TUE NIGHT BEFORE BECOMING STATIONARY FROM NE MO
ACROSS CENTRAL IL TO NORTHERN IND BY WED MORNING. INCREASING FLOW
FROM THE CENTRAL PLAINS ENE ACROSS THE MID MS VALLEY WILL RESULT
IN INCREASING WARM AIR ADVECTION AS WELL AS MID AND LOWER LEVEL
MOISTURE TRANSPORT INTO THE AREA WITH CHANCES OF SHOWERS AND
THUNDERSTORMS...MAINLY FOR THE N 1/2 TO 3/4 OF THE LOCAL FORECAST
AREA TUE THROUGH WED BEFORE A STRONG SHORT WAVE DROPPING ACROSS
THE UPPER MIDWEST AND WESTERN GREAT LAKES PUSHES THE SURFACE FRONT
FURTHER TO THE S AND ANOTHER LARGE SURFACE ANTICYCLONE BUILDS OVER
THE UPPER MIDWEST AND THE GREAT LAKES DURING WED AND WED NIGHT.
WED NIGHT THROUGH FRI WILL HAVE LOW POPS AS THE HIGH PRESSURE WILL
DOMINATE THE WEATHER OVER THE REGION...CONTINUING TO FEED COOL DRY
AIR ACROSS THE AREA.
TRS
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.CLIMATE...
RECORD LOW SEP 23
CHICAGO 29 1995
ROCKFORD 29 1974
EARLIEST FIRST FREEZE DATE
CHICAGO SEP 22 1995 /32F/
ROCKFORD SEP 13 1975 /32F/
AVERAGE FIRST FREEZE DATE
CHICAGO OCT 15
ROCKFORD OCT 7
TRS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* PERIODS OF SHOWERS THIS MORNING...WITH PATCHY MVFR CONDITIONS
POSSIBLE.
* STRONG NORTHWEST WINDS GUSTING UP TO 30 KTS...ESPECIALLY THIS
MORNING FOLLOWING THE FRONTAL PASSAGE.
KJB
//DISCUSSION...UPDATED 06Z...
THE MAIN FORECAST CONCERNS TODAY WILL BE THE ONSET OF STRONG
NORTHWEST WINDS THIS MORNING IN THE WAKE OF STRONG COLD FRONTAL
PASSAGE.
CURRENTLY THIS STRONG COLD FRONT IS PUSHING ACROSS FAR SOUTHEASTERN
MINNESOTA AND FAR NORTHERN IOWA. THE FRONT SHOULD ARRIVE AT KRFD
AROUND DAYBREAK AND AROUND 14 UTC AT THE NORTHEASTERN ILLINOIS
SITES. DIRECTLY IN THE WAKE OF THIS FRONT STRONG COLD AIR ADVECTION
AND RAPID PRESSURE RISES HAVE BEEN RESULTING IN WIND GUSTS UP TO
AROUND 30 KT ACROSS MINNESOTA. I EXPECT THESE TYPES OF GUSTS TO BE
REALIZED HERE AS WELL FOR AN HOUR OR TWO FOLLOWING THE FRONTAL
PASSAGE THIS MORNING. THE WINDS SHOULD WEAKEN SOME THIS
AFTERNOON...BUT EXPECT THEM TO REMAIN GUSTY AROUND 20 TO 25 KT AT
TIMES.
THERE WILL ALSO BE PERIODS OF SHOWERS THROUGH THE MORNING HOURS. AN
AREA OF LIGHT SHOWERS IS CURRENTLY APPROACHING THE TERMINALS. THIS
ACTIVITY WILL BE A QUICK HIT...AND MOVE OUT SHORTLY AFTER 07 UTC.
HOWEVER...ADDITIONAL ACTIVITY WILL LIKELY DEVELOP TO OUR NORTHWEST
OVERNIGHT AND SHOULD AFFECT THE AREA THROUGH THE MORNING HOURS AS A
STRONG MID LEVEL ATMOSPHERIC DISTURBANCE SHIFTS SOUTHEASTWARD ACROSS
NORTHERN ILLINOIS. IT ALSO APPEARS THERE WILL BE SOME LOWER CIGS
THROUGH THE MORNING HOURS FOLLOWING THE FRONTAL PASSAGE.
HOWEVER...IT APPEARS THE CIGS WILL REMAIN ABOVE 1500 FEET
AGL...AND ANY MVFR CIGS SHOULD IMPROVE DURING THE AFTERNOON.
KJB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* MEDIUM-HIGH CONFIDENCE IN WIND TRENDS TONIGHT.
* MEDIUM CONFIDENCE IN TIMING OF PRECIP/CIGS THROUGH PERIOD.
* HIGH CONFIDENCE IN WIND TRENDS SATURDAY.
KJB
//OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z...
SUNDAY...VFR. DIMINISHING WEST-NORTHWEST WINDS.
MONDAY...VFR.
TUESDAY...VFR. CHC SHRA.
WEDNESDAY...VFR.
THURSDAY...VFR.
RATZER
&&
.MARINE...
230 PM CDT
LOW PRESSURE OVER THE UPPER GREAT LAKES WILL TRACK NORTHEAST
TOWARD HUDSON BAY OVERNIGHT TONIGHT AND THEN RAPIDLY DEEPEN
TOMORROW AS STRONG HIGH PRESSURE BUILDS ACROSS THE NORTHERN
PLAINS. A SERIES OF MID LEVEL IMPULSES WILL BRING REINFORCING
SHOTS OF COLD AIR OVER THE WESTERN GREAT LAKES TOMORROW. THE
RESULTANT STRONG COLD ADVECTION WILL LEAD TO RAPIDLY
STRENGTHENING NORTHERLY WINDS TOMORROW...LIKELY REACHING GALE
FORCE DURING THE AFTERNOON HOURS. THE PRESSURE GRADIENT AND COLD
ADVECTION WILL BE STRONGEST OVER THE FAR NORTHERN PORTIONS OF THE
LAKE...SO HAVE HOISTED A GALE WARNING FOR THE NORTHERN ONE-THIRD
OF THE LAKE. THE WINDOW OF OPPORTUNITY FOR THE STRONGEST WINDS
WILL BE DURING THE AFTERNOON AND EVENING HOURS WHEN HIGH PRESSURE
SPREADING INTO THE WESTERN GREAT LAKES SHOULD HELP ALLOW WINDS TO
SUBSIDE BELOW GALE FORCE. FOR THE SOUTHERN PORTIONS OF THE
LAKE...WINDS AND WAVES SHOULD QUICKLY RISE TO SMALL CRAFT
ADVISORY LEVELS TOMORROW AS WELL...WITH THE INDIANA WATERS
REACHING SMALL CRAFT ADVISORY LEVELS SOONER THAN THE ILLINOIS
WATERS...AND LINGERING LONGER...INTO MONDAY MORNING DUE TO THE
GENERALLY NORTHERLY FETCH SETTING UP OVER THE LAKE. BY MONDAY
AFTERNOON...ANOTHER DEEPENING LOW TRACKING JUST NORTH OF THE
GREAT LAKES MAY POSSIBLY BRING ANOTHER BRIEF PERIOD OF
SOUTHWESTERLY GALES TO THE FAR NORTHERN PORTION OF THE LAKE...
BUT WILL NOT ISSUE ANY HEADLINES AT THIS TIME SINCE THE STRENGTH
OF THE WINDS WILL BE HIGHLY DEPENDENT ON THE EXACT TRACK OF THE
LOW.
THE OTHER CONCERN FOR LAKE MICHIGAN WILL BE WATERSPOUT POTENTIAL.
LAKE SFC WATER TEMPERATURES REMAIN UNUSUALLY HIGH...WITH A
TEMPERATURE OF 17C AT THE NORTH BUOY AND 20C AT THE SOUTH BUOY
THIS AFTERNOON. WHEN THE MUCH COOLER AIR PLUNGES OVER LAKE
MICHIGAN...LAKE SFC TO 850MB DELTA-T VALUES WILL REACH AS HIGH AS
22-23C...INDICATIVE OF A VERY UNSTABLE ENVIRONMENT OVER LAKE
MICHIGAN. WHILE CONVERGENCE BOUNDARIES ARE NOT LIKELY OVER THE
LAKE...WATERSPOUT POTENTIAL WILL REMAIN HIGH DUE TO LAKE EFFECT
RAIN SHOWERS AND DEEP LAYER CONVECTIVE CLOUD DEVELOPMENT.
CONDITIONS WILL BE CONDUCIVE TO WATERSPOUTS FROM THIS EVENING
THROUGH MONDAY EVENING...ESPECIALLY FOR THE NORTHERN AND EASTERN
PORTIONS OF THE LAKE.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...HIGH RIP CURRENT RISK...INZ001-INZ002...10 AM SATURDAY TO 10 AM
MONDAY.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...2 PM SATURDAY TO 11
PM SATURDAY.
SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743...4 PM
SATURDAY TO MIDNIGHT MONDAY.
SMALL CRAFT ADVISORY...LMZ744-LMZ745...10 AM SATURDAY TO 10 AM
MONDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1118 PM CDT FRI SEP 21 2012
.DISCUSSION...
ISSUED 842 PM CDT FRI SEP 21 2012
SURFACE LOW LOCATED JUST NORTHWEST OF EFFINGHAM...TRACKING ESE
WITH THE ATTENDANT COLD FRONT. SCATTERED CONVECTION CONTINUES
TO SLOWLY WEAKEN ALTHOUGH WE ARE STILL SEEING SOME WEAK
CIRCULATIONS ALONG THE WARM FRONT OVER PARTS OF SE IL FROM TIME
TO TIME. EXPECT THE WEAKENING TRENDS TO CONTINUE. NORTH OF THE
COLD BOUNDARY...WINDS WERE OUT OF THE NORTH WITH TEMPERATURES
SETTLING BACK INTO MID AND UPPER 40S ACRS THE NORTH...WHILE SOUTH
OF THE COLD FRONT...TEMPERATURES WERE STILL IN THE LOW 70S OVER
PARTS OF SE IL.
THE FRONT SHOULD SHIFT SOUTH AND EAST OF OUR AREA BY MIDNIGHT
TAKING THE RAIN THREAT WITH IT. FURTHER TO OUR NORTHWEST...A
SECONDARY COLD FRONT WAS TRACKING SE OUT OF THE NORTHERN MIDWEST
BRINGING ANOTHER BAND OF SHOWERS SOUTH WITH IT. STILL APPEARS OUR
NORTHERN AREAS STAND THE BEST CHANCE OF SEEING SOME WDLY SCT
SHOWERS BY DAWN. ADJUSTMENTS WERE MADE TO THE HOURLY TEMPERATURE
GRIDS AS WELL AS WITH THE OVERNIGHT LOWS AS A LOCATIONS...ESP ACRS
THE NORTH...WERE ALREADY AT OR BELOW THE FORECAST LOWS FOR THE
NIGHT. THE UPDATED ZONES SHOULD BE OUT AROUND 900 PM.
&&
.AVIATION...
ISSUED 1105 PM CDT FRI SEP 21 2012
SOME PATCHY FOG POSSIBLE THRU THE EARLY MORNING HOURS...ESP IN
AREAS THAT RECEIVED RAINFALL TODAY. WILL MAKE A LAST MINUTE
DECISION ON INCLUDING MVFR VSBYS DURING THE MORNING. IT APPEARS
THE MORE WIDESPREAD FOG IS DEVELOPING JUST SOUTH OF THE TAF
SITES LATE TONIGHT. OTHERWISE...THE REMAINDER OF THE FORECAST
PERIOD SHOULD HAVE VFR CONDITIONS. A SECONDARY COLD FRONT WAS
PUSHING SE OUT OF THE NORTHERN MIDWEST AND WILL STREAK SE INTO OUR
AREA SATURDAY MORNING. SATELLITE DATA INDICATES SOME SCT-BKN MID
LEVEL CLOUDS TO OUR NORTH WHICH WILL AFFECT MAINLY OUR NORTH AND
EAST TAF SITES (PIA...BMI AND CMI). MAY SEE SOME LIGHT RAIN/SPRINKLES
WITH THE MID CLOUD...BUT AT THIS TIME...COVERAGE APPEARS TO BE
TOO LIMITED TO INCLUDE IN TAFS FOR NOW.
SFC WINDS AHEAD OF THE SECONDARY FRONT SHOULD BACK INTO THE WEST
OR SW FOR A BRIEF TIME EARLY SATURDAY BEFORE SWITCHING INTO THE NW
AND INCREASING DURING THE DAY. WINDS SATURDAY SHOULD AVERAGE FROM
12 TO 17 KTS WITH GUSTS AROUND 25 KTS AT TIMES. FORECAST SOUNDINGS
SUGGEST WE MAY SEE SOME SCATTERED CU DEVELOP WITH THE INCREASING
WINDS AND COLD ADVECTION. LOOKS LIKE BASES OF THE CU WILL RANGE
FROM 4000-5000 FEET....WHICH SHOULD DISSIPATE QUICKLY JUST BEFORE
SUNSET ALONG WITH THE WINDS.
SMITH
&&
.PREV DISCUSSION...
ISSUED 300 PM CDT FRI SEP 21 2012
SHORT TERM...TODAY THROUGH MONDAY
INITIAL CONCERN IS SLIGHT RISK OF SEVERE STORMS INTO EARLY EVENING
MAINLY EAST OF THE IL RIVER. SHORT RANGE MODELS FAIRLY SIMILAR
THROUGH MON WITH STRONG UPPER LEVEL TROF DIGGING SOUTHWARD INTO
THE GREAT LAKES AND OHIO VALLEY REGION BY SAT WITH BELOW NORMAL
TEMPS EXPECTED THIS WEEKEND. PATCHY FROST STILL A POSSIBILITY OVER
THE IL RIVER VALLEY LATER SAT NIGHT AND IN EASTERN IL LATER SUNDAY
NIGHT. MET AND MAV GUIDANCE TEMPS SIMILAR THROUGH SUNDAY NIGHT AND
STAYED FAIRLY CLOSE TO.
MID AFTERNOON SURFACE MAP SHOWS 1006 MB LOW PRESSURE DEEPENING
ALONG THE EASTERN IA/MO BORDER WITH ITS WARM FRONT LIFTING
NORTHWARD TOWARD I-74...AS ENE WINDS TURN SOUTH WITH ITS PASSAGE AND
DEWPOINTS IN THE UPPER 30S AND 40S RISE INTO THE MID TO UPPER 50S.
TEMPS RISING AS WELL INTO THE UPPER 70S AND LOWER 80S IN SW IL IN
WARM SECTOR WHERE ALSO MORE SUNSHINE. SOME INSTABILITY WITH CAPES
PEAKING FROM 1000-1500 J/KG EAST OF THE IL RIVER THIS AFTERNOON
WITH INCREASING WIND SHEAR AS WELL DURING MID/LATE AFTERNOON INTO
EARLY EVENING AS 35-40KT WSW LOW LEVEL JET WHILE ALSO GETTING
STRONGER THAN 80-100 KT JET ALOFT DIVING SE INTO IL LATE TODAY
ALONG WITH A SHORT WAVE MOVING INTO CENTRAL IL FROM IA LATE TODAY.
VGP PARMETERS ARE FAVORABLE FOR ISOLATED TORNADOES IN SE IL LATE
THIS AFTERNOON/EARLY EVENING. SO CONCUR WITH SPC/S UPGRADE TO A
SLIGHT RISK OF SEVERE STORMS FROM MID AFTERNOON INTO EARLY EVENING
MAINLY SE OF THE IL RIVER. SPC HAS 15% RISK OF LARGE HAIL AND
DAMAGING WIND GUSTS ALONG WITH 5% RISK OF TORNADOES.
LOW PRESSURE DEEPENS A BIT MORE TO 1005 MB AND DIVES SE INTO SW IL
BY SUNSET AND THEN TURN NE ACROSS THE OHIO RIVER THIS EVENING.
RUC13 AND HRRR MODELS KEEP HEALTHY CHANCES OF SHOWERS AND
THUNDERSTORMS OVER EASTERN IL THROUGH MID EVENING AND THEN
DIMINISH BY LATE EVENING AND TRENDED FORECAST IN THAT DIRECTION.
WESTERN IL SHOULD BE DRY THIS EVENING WITH CONVECTION EAST OF
THERE. LOWS TONIGHT RANGE FROM THE LOWER 40S NW OF THE IL RIVER TO
THE LOWER 50S SE OF I-70 IN SE IL.
UNSEASONABLY STRONG 533 DM 500 MB DOUBLE BARREL LOW OVER NW
ONTARIO TO CONTINUE DIGGING SOUTHWARD INTO THE GREAT LAKES AND
OHIO VALLEY TONIGHT/SAT WHILE SENDING A STRONG SHORT WAVE FROM
LAKE WINNIPEG SE INTO EASTERN IA/NORTHERN IL/SW WI BY SUNRISE SAT
AND INTO NORTHERN INDIANA BY 18Z/1 PM SAT. CONTINUE 20% CHANCE OF
SHOWERS LATE TONIGHT NORTH OF PEORIA AND 20-30% CHANCE NE OF I-74
SAT MORNING ALONG WITH GUSTS NORTH WINDS UP TO 30 MPH NE AREAS.
HIGHS AROUND 60F FROM I-74 NE SAT AND MID 60S IN SE IL AND SW OF
SPRINGFIELD.
1026 MB HIGH PRESSURE OVER SASKETCHEWAN TO BUILD INTO THE EASTERN
PLAINS SUNDAY AND RETURN LIGHER WINDS TO THE AREA BUT CONTINUE
COOL WEATHER. FROST IS LIKELY OVER THE IL RIVER VALLEY LATER SAT
NIGHT WITH LOWS IN THE MID 30S. APPEARS SHY OF RECORD LOWS AROUND
30F EARLY SUNDAY MORNING SEP 23 BUT NEAR FREEZING TEMPS POSSIBLE
IN NW IL NW OF KNOX AND STARK COUNTIES. PATCHY FROST IS POSSIBLE
OVER EASTERN IL LATER SUNDAY NIGHT WITH LOW IN THE MID TO UPPER
30S AS SURFACE HIGH DRIFTS OVER CENTRAL/SE IL AND EVENTUALLY INTO
THE OHIO RIVER VALLEY BY DAWN MON. HIGHS SUNDAY STAYING COOL IN THE
LOW TO MID 60S DESPITE A FAIR AMOUNT OF SUNSHINE.
LONG TERM...MONDAY NIGHT THROUGH FRIDAY
UNSETTLED WEATHER PATTERN TAKING SHAPE LATER MON NIGHT THROUGH MID
WEEK AS SEVERAL SHORT WAVES WILL EJECT FROM THE CENTRAL PLAINS
TOWARD IL AND ALSO HAVE A FRONTAL BOUNDARY MOVING SOUTHWARD AND
POSSIBLY LINGERING NEAR CENTRAL/SE IL FOR A FEW DAYS DURING
MIDWEEK. THIS WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS
AROUND FOR A FEW DAY BUT THINK GFS IS LINGERING QPF TOO LONGER
INTO LATE WEEK AND LEANED TOWARD THE FURTHER SOUTH ECWMF MODEL
WITH THE FRONT BY THU/FRI. GENERALLY STAYED CLOSE TO ALLBLEND POPS
DURING NEXT WORK WEEK AND LINGERED SLIGHT CHANCES SOUTHERN AREAS
AROUND THU. TEMPERATURES TO WARM BACK TO NORMAL BY TUE AND COOLING
OFF FROM NORTH TO SOUTH LATER NEXT WEEK AND COULD BE MORE OF A
TEMPERATURE CONTRAST THAN WHAT ALLBLEND IS SHOWING DURING 2ND HALF
OF NEXT WEEK DEPENING ON POSITION OF FRONTAL BOUNDARY.
KH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1225 AM EDT SAT SEP 22 2012
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 236 PM EDT FRI SEP 21 2012
A SURFACE WAVE AND COLD FRONT WILL MOVE OUT OF CENTRAL INDIANA
OVERNIGHT WITH WIDESPREAD RAINFALL ENDING. IT WILL BE MUCH COOLER
ON SATURDAY WITH A CHANCE OF SHOWERS ACROSS THE NORTHERN HALF OF
CENTRAL INDIANA AS AN UPPER WAVE PASSES ACROSS NORTHERN INDIANA.
THEN...EXPECT DRY WEATHER WITH MUCH BELOW NORMAL TEMPERATURES
THROUGH MONDAY AS HIGH PRESSURE BUILDS IN FROM THE CANADIAN
PRAIRIES. AFTERNOON TEMPERATURES ARE ONLY EXPECTED TO REACH THE
60S. NORTHERN SECTIONS WILL ONLY SEE THE UPPER 50S THROUGH SUNDAY.
MEANWHILE AREAS AWAY FROM THE CITY SHOULD BOTTOM OUT IN THE 30S
SATURDAY NIGHT AND SUNDAY NIGHT. PATCHY FROST WILL BE POSSIBLE
ESPECIALLY SUNDAY NIGHT. THUNDERSTORM CHANCES WILL RETURN BY
MONDAY NIGHT AS A FRONT DROPS DOWN FROM THE NORTH. TEMPERATURES
WILL WARM BACK INTO THE 70S BY TUESDAY AS HIGH PRESSURE SHIFTS TO
THE EAST COAST ALLOWING RETURN FLOW FROM THE GULF OF MEXICO.
&&
.NEAR TERM /OVERNIGHT/...
ISSUED AT 1047 PM EDT FRI SEP 21 2012
LOW PRESSURE CURRENTLY LOCATED OVER WESTERN INDIANA AS OF 02Z.
LINEAR CONVECTION NOW LARGELY CONFINED TO POINTS ALONG AND SOUTH
OF A MUNCIE TO INDY METRO TO TERRE HAUTE LINE. TEMPS REMAINED IN
THE 60S OVER SOUTHERN COUNTIES WHERE RAIN HAD NOT YET FALLEN...
WITH CHILLY 50S ELSEWHERE.
THE LOW WILL TRACK EAST ACROSS THE FORECAST AREA OVER THE NEXT
FEW HOURS WITH THE ASSOCIATED FRONTAL BOUNDARY STEADILY PUSHING
SOUTH AND EAST OUT OF THE FORECAST AREA. HAVE LEANED HEAVILY ON
THE HRRR FOR THE OVERNIGHT WITH THE BULK OF THE RAINFALL LIKELY TO
BE OUT OF THE FORECAST AREA BY 06-07Z WITH JUST LIGHT SCATTERED
PRECIP IN ITS WAKE. ADJUSTED POPS TO ACCOUNT FOR THIS THINKING.
SATELLITE TRENDS SUGGEST CLOUDS WILL SCATTER PRIOR TO DAYBREAK AND
WITH LIGHTENING WINDS AND WET GROUND FROM THE EVENING RAIN...MAY
SEE SOME PATCHY FOG DEVELOP LATE AS WELL.
ZONE AND GRID UPDATES OUT.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 150 PM EDT FRI SEP 21 2012
THE MAIN FOCUS OVER THE SHORT TERM WILL BE ON POPS ON SATURDAY ALONG
WITH TEMPERATURES...AND FROST POTENTIAL MAINLY SUNDAY OVERNIGHT.
MODELS ALL IN GOOD AGREEMENT ON PERSISTENT HUDSON BAY VORTEX WITH
UPPER WAVES DROPPING AROUND THE BASE OF THE ASSOCIATED TROUGH.
MODELS HAVE ONE SUCH WAVE MOVING TO NEAR SOUTH BEND BY 18Z SATURDAY
WITH A COMPACT AREA OF DEEPER MOISTURE ASSOCIATED WITH IT. THIS
SUGGESTS LIGHT QPF ACROSS OUR NORTH PER THE MODELS LOOKS GOOD. WILL
USE ALLBLEND. BY SATURDAY NIGHT...THERE SHOULD BE LITTLE CLOUD COVER
AS CANADIAN HIGH PRESSURE BUILDS IN. SUNDAY NIGHT WILL FIND THE
SURFACE HIGH NEAR LOUISVILLE WITH LIGHT TO CALM WINDS AND CLEAR
SKIES. THIS COULD ALLOW PATCHY FROST EXCEPT NEAR THE CITY.
MOS TEMPERATURES PRETTY CLOSE THROUGH THE PERIOD AND APPEARS
REASONABLE.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 228 PM EDT FRI SEP 21 2012
SEVERAL WAVES WILL MOVE THROUGH THE MAIN FLOW...AN UPPER LEVEL
TROUGH...THROUGH MUCH OF THE LONG TERM. WHILE MODELS SHOW SOME
SLIGHT DIFFERENCES IN THE DETAILS...ALL SHOW A FRONT WILL MOVE INTO
CENTRAL INDIANA AND STALL OUT OVER THE AREA. THIS WILL KEEP CHANCES
FOR SHOWERS AND THUNDERSTORMS /DUE TO THE PRESENCE OF AT LEAST
ELEVATED INSTABILITY/ IN THE FORECAST FROM MONDAY NIGHT THROUGH
WEDNESDAY NIGHT. FROM THURSDAY ON THE MODELS SHOW MORE VARIABILITY.
0Z ECM SHOWS THE FRONT SLOWLY MOVING THROUGH THE AREA TUE AND WEDS
AND WASHING OUT SOUTH OF THE AREA ON THU WITH DRY WEATHER HERE AND
HIGH PRESSURE BUILDING IN. GFS ENSEMBLE AVERAGE SHOWS THE FRONT
STILL ACROSS THE AREA ON THURSDAY AND NOT SHOVED SOUTH UNTIL THU
NIGHT. 12Z GFS IS A LITTLE SLOWER THAN 0Z ECMWF AND ALSO BRINGS
ANOTHER WAVE UP FROM THE SOUTHWEST LATE THURSDAY NIGHT/FRIDAY
MORNING. WITH WIDE SPREAD IN THE ENSEMBLES FROM THURSDAY ON WILL
STICK WITH ALLBLEND AND KEEP SLIGHT CHANCES IN THE SOUTH DURING THAT
TIME.
AS FAR AS TEMPERATURES ARE CONCERNED WENT WITH ALLBLEND FOR HIGHS
GENERALLY IN THE UPPER 60S TO MIDDLE 70S UNTIL FRIDAY...BUT WOULD
NOT BE SURPRISED TO SEE A TIGHTER GRADIENT ACROSS THE AREA DEPENDING
ON WHERE THE FRONT SETS UP. ALLBLEND LOWS IN THE 50S LOOK GOOD WITH
SOME CLOUD COVER GIVEN THE FRONT.
&&
.AVIATION /DISCUSSION FOR THE 22/06Z TAFS/...
ISSUED AT 1225 AM EDT SAT SEP 22 2012
SHOWERS AND THUNDERSTORMS ARE ALL CLEAR OF THE SITES. CONCERNED
ABOUT POTENTIAL FOR FOG OR STRATUS IN THE WAKE OF AMPLE RAINFALL
ACROSS THE AREA DURING THE EVENING. WILL GO WITH 5SM/TEMPO 3SM FOR
NOW WITH SCT004 TO HINT AT STRATUS POSSIBILITY. THIS IS DEPENDENT ON
HOW QUICKLY WE CLEAR...AND CONFIDENCE IS MIDDLING.
TOMORROW...EXPECT ADDITIONAL CLOUD COVER TO DEVELOP...AND WINDS TO
GUST NEAR 25-30KT AT TIMES.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...MK/RYAN
NEAR TERM...RYAN
SHORT TERM...MK
LONG TERM....CP
AVIATION...NIELD
AREA FORECAST DISCUSSION
NWS DES MOINES IA
404 AM CDT SAT SEP 22 2012
.SHORT TERM /TODAY/...
MAIN FORECAST CONCERN IS WITH WINDS AND TEMPS
TODAY WITH STRONG CAA DEVELOPING BEHIND THE COLD FRONT THAT PUSHED
ACROSS MUCH OF THE CWA EARLY THIS MORNING. LEANED TOWARD A
NAM/RAP/SREF BLEND TODAY AS ALL MODELS ARE IN GOOD AGREEMENT. 03Z
HRRR/05Z RAP DEPICT A STRATUS DECK LOCATED IN NORTHERN MN TO ARRIVE
IN NORTHERN IOWA BY AROUND 12Z AND THEN DISSIPATE BY AROUND 18Z.
INCREASED CLOUD COVER OVER THE NORTH TO NORTHEAST THIS MORNING AS A
RESULT. THIS WILL HINDER THE MAX TEMP SLIGHTLY AND WENT A LITTLE
COOLER IN THIS AREA. OTHERWISE...STRONG NORTHWEST WINDS WILL BE
COMMON THROUGHOUT THE DAY WITH FAIRLY TIGHT PRESSURE GRADIENT AND
DECENT MIXING BEFORE HIGH SETTLES IN LATE THIS AFTERNOON. TWEAKED
WINDS UP SLIGHTLY WITH THIS SCENARIO AS CURRENT WINDS UPSTREAM ARE
GUSTING TO 20-25KTS.
.LONG TERM /TONIGHT THROUGH FRIDAY/...
COLD CANADIAN HIGH PRESSURE WILL INTO CENTRAL IOWA TONIGHT. THE HIGH
WILL REINFORCE THE VERY DRY AIR THAT IS FELTING INTO THE STATE THIS
MORNING AND EXPECT DEWPOINTS OVERNIGHT TO BE WELL INTO THE 20S OVER
THE NORTH AND WEST. CURRENTLY A LARGE ARE OF STRATUS ALONG THE
EASTERN FRINGE OF THE HIGH THUS THERE IS SOME UNCERTAINTY THAT THIS
STRATUS MAY AFFECT AREAS EAST OF INTERSTATE 35 OVERNIGHT AND PROVIDE
ENOUGH INSOLATION TO HOLD READINGS UP. 925 MB WIND TRAJECTORIES
REMAIN ROUGHLY 340-360 DEGREES THROUGH TODAY AND TONIGHT. MUCH OF
THE REGION SHOULD HAVE ENOUGH SUBSIDENCE WITH THE APPROACHING HIGH
TO ERODE MUCH OF IT. FOR AREAS THAT HAVE MOSTLY CLEAR SKIES...THE
DIMINISHING WINDS AND VERY DRY AIR WILL ALLOW TEMPERATURES TO
PLUMMET OVERNIGHT TO RECORD OR NEAR RECORD LOW VALUES. THESE VALUES
ARE BELOW FREEZING FOR ALL LOCATIONS EXCEPT THE FAR SOUTH AND
SOUTHEAST. HAVE ISSUED A FREEZE WARNING FOR ALL LOCATIONS WITH
FORECAST LOWS BELOW 32 TONIGHT. HAVE LEFT THE FREEZE WATCH OUT FOR
THE SOUTH CENTRAL WHERE READINGS WILL BE A BIT WARMER. GIVEN THE
VERY DRY AIR...FROST MAY NOT BE PREVALENT IN THESE AREAS DESPITE THE
TEMPERATURES SO NO CONFIDENCE IN FROST HEADLINES IN THAT REGION.
KEEPING THE FREEZE WATCH WILL GIVE THE FOLLOWING SHIFT SOME WIGGLE
ROOM WITH THE HEADLINES IF MORE COLD AIR THAN ANTICIPATED ARRIVES BY
TONIGHT.
SUNDAY WILL BE PLEASANT THOUGH COOL WITH MOSTLY SUNNY SKIES AND
LIGHT NORTHWEST WINDS. HIGH PRESSURE SLIDES TO THE SOUTHEAST SUNDAY
NIGHT. WILL HAVE QUICK COOLING SUNDAY EVENING BEFORE SOUTHERLY FLOW
GRADUALLY RETURNS LATE. POSSIBLE FOR NEAR FREEZING TEMPERATURES
AGAIN OVER THE NORTHEAST WHERE RETURN FLOW WILL ARRIVE LAST.
READINGS WILL BE MILD MONDAY AND TUESDAY WITH 850 MB THERMAL RIDGING
MOVES INTO THE STATE. MORE UNCERTAINTY ARRIVES FOR WEDNESDAY THROUGH
FRIDAY WITH THE TRANSITION FROM NORTHWEST TO ZONAL FLOW OCCURS. THE
TRANSITION WILL ALLOW THE ENERGY FROM WEST COAST UPPER LOW AND A
PACIFIC NORTHWEST SYSTEM TO MOVE TOWARD THE REGION WHILE A MID LEVEL
BOUNDARY LIFTS TOWARD THE STATE. CURRENTLY HAVE SEVERAL PERIODS WITH
POPS WITH THE BEST POTENTIAL WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
THE 500 MB FLOW DURING THIS PERIOD IS UNORGANIZED ENOUGH THAT IT IS
GIVING GUIDANCE PROBLEMS ON EXACT PLACEMENT OF WHERE THE SHORTWAVES
WILL MOVE THROUGH.
&&
.AVIATION...22/06Z
FRONTAL PASSAGE OVERNIGHT WILL LEAD TO STRONG AND GUSTY WINDS ACROSS
SITES BEHIND FRONT...WINDS WILL BE MAINLY FROM THE NORTHWEST.
DECREASING CONFIDENCE IN PRECIPITATION ACROSS THE NE
SITES...KMCW/KALO...BUT HAVE LEFT VCSH MENTION WITH PRECIPITATION
CURRENTLY ONGOING UPSTREAM OF SITES. WINDS WILL REMAIN STRONG AND
NORTHWESTERLY THROUGHOUT THE PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING LATE TONIGHT THROUGH SUNDAY MORNING FOR
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-
WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-
GREENE-BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-CASS-
ADAIR-ADAMS-TAYLOR-
FREEZE WATCH LATE TONIGHT THROUGH SUNDAY MORNING FOR
POLK-JASPER-POWESHIEK-MADISON-WARREN-MARION-MAHASKA-UNION-CLARKE-
LUCAS-MONROE-WAPELLO-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...AWB
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1158 PM CDT FRI SEP 21 2012
.UPDATE...
ISSUED AT 754 PM CDT FRI SEP 21 2012
MESOSCALE UPDATE /754 PM CDT/...BASED ON THE KVWX WSR-88D VAD WIND
PROFILE...50 KNOT WINDS REACHED NEAR A 9-10KFT MSL LEVEL AROUND
0010 UTC...ABOUT TWENTY MINUTES AFTER THE BASE OF A PROGRESSIVE
SHORTWAVE REACHED THAT LEVEL. THIS ENHANCEMENT OF FASTER WINDS
ALOFT /IMPLIED SHARPENING OF LAPSE RATES/ MAY HAVE SUPPORTED THE
BRIEF INTENSIFICATION OF STORMS OVER NORTHERN JEFFERSON COUNTY
ILLINOIS THIS EVENING...AS SURFACE MOISTURE CONVERGENCE AND
INSTABILITY /NOTED IN THE LAPS SURFACE FIELDS WAS MAXIMIZED.
SURFACE LAPS DATA AT 23Z-00Z INDICATED A DECREASING SURFACE-BASED
CAPE GRADIENT AS THE STORMS MOVE TOWARD THE WABASH RIVER INTO
SOUTHWEST INDIANA...ALTHOUGH SURFACE BASED THETA-E CONVERGENCE
REMAINS STRONG IN THIS AREA. LOW LEVEL WIND FIELDS AT OR ABOVE
2KFT AGL HAS STRENGTHENED SLIGHTLY /0-5 KNOTS/ WITH SLIGHT VEERING
WITH HEIGHT THROUGH 10KFT AGL...SUGGESTING SOME DECOUPLING AT THE
SURFACE AND POSSIBLY THE DEVELOPMENT OF A WEAK LOW LEVEL JET.
THE 00Z SATURDAY GOES SOUNDER PRECIPITABLE WATER AND LIFTED INDEX
VALUES HAVE SHIFTED THE HIGHEST LAYER MOISTURE AND MARGINAL
INSTABILITY TOWARD THE PENNYRILE REGION OF WEST KENTUCKY.
WITH ALL OF THIS IN MIND...IT WILL BE DIFFICULT TO KEEP IN PHASE
AND MAINTAIN DEEP MOISTURE AND INSTABILITY FOR SUSTAINED AND
ROBUST UPDRAFTS AS THE CONVECTION MOVES ACROSS THE WABASH RIVER
OVER SOUTHWEST INDIANA.
HOWEVER...IR SATELLITE IMAGERY STILL SHOWS PERSISTENT WATER CLOUD
EAST OF THE CURRENT CONVECTIVE ACTIVITY...POSSIBLY ADDED BY LARGE
SCALE SYNOPTIC LIFT. AS THE ZONE OF STRONGER WINDS INTERACTS WITH
THIS LAYER...WE MAY SEE ELEVATED SHOWERS /AND POSSIBLY A
THUNDERSTORM OR TWO/ EXPAND SLOWLY SOUTH AND EAST BETWEEN 8PM AND
10 PM INTO THE PENNYRILE REGION OF WEST KENTUCKY. ANY SEVERE
POTENTIAL WILL BE MINIMAL TO NON-EXISTENT.
THE NEWLY ARRIVED 01Z SATURDAY SPC DAY ONE OUTLOOK HAS SHIFTED ANY
REMAINING SLIGHT RISK OF SEVERE STORMS OUT OF THE WFO PAH FORECAST
AREA.
ANY CONVECTION AT ALL SHOULD BE OUT OF THE WFO PAH CWA NO LATER
THAN 06Z...1 AM CDT SATURDAY.
UPDATE ISSUED AT 556 PM CDT FRI SEP 21 2012
FORECAST UPDATE...18Z NAM 12KM AND 12Z ECMWF SEEM TO HAVE A GOOD HANDLE ON
CURRENT TRENDS. HAVE FOCUSED POPS THIS EVENING OVER THE NORTH 1/2
OF THE AREA WHERE SLIGHTLY DEEPER MOISTURE EXISTS. TEMPERATURES
THROUGH EARLY EVENING WERE UPDATED...AS EXISTING VALUES WERE
COOLING TOO FAST TOO QUICKLY GIVEN THE WINDS AHEAD OF AND WITH THE
FRONT AND CURRENT CONDITIONS. THE RUC AND NAM DNG TEMPS SUPPORT
THIS TREND. ONLY MINOR ADJUSTMENTS TO CLOUDS.
MESOSCALE UPDATE /622 PM CDT/...VISIBLE AND INFRARED SATELLITE TRENDS
SHOWED THE EVOLUTION OF ENHANCED CLOUD TOPS AT 2045Z AROUND THE
ST. LOUIS METRO AREA...WITH THE TRANSITION OF WATER TO ICE CLOUD
SHOWING UP BETWEEN 2300-2330Z TIME FRAME.,,SUGGESTING SHARPER
LAPSE RATES ALOFT TYING IN WITH SURFACE BASED INSTABILITY AND
MOISTURE JUST OUTSIDE THE WFO PAH COUNTIES IN SOUTHERN IL. GOES
SOUNDER PRECIPITABLE WATER VALUES DURING THE PAST HOUR SHOW A GOOD
PLUME OF 1.2 TO 1.5 INCHES OF WATER OVER SOUTHERN
ILLINOIS...SPREADING SOUTH AND IN EAST INTO SOUTHEAST
MISSOURI...WEST KENTUCKY AND SOUTHWEST INDIANA. THE LIMITING
FACTOR...BASED ON SURFACE INSTABILITY...IS SUGGESTED BY THE GOES
SOUNDER LIFTED INDEX AROUND 22Z. THE ZERO TO MINUS FOUR VALUES
ONLY GO DOWN AS FAR AS ROUTE 13 IN SOUTHERN ILLINOIS. THIS IS
CLOSE TO THE 20Z SPC SLIGHT RISK AREA DEPICTED EARLIER THIS
AFTERNOON.
AS THE BOUNDARY LAYER SLOWLY COOLS IN THE WARM SECTOR...ANTICIPATE
SOME GRADUAL REDUCTION IN SURFACE MIXING OF AIR PARCELS...WITH THE
EXCEPTION OF THE COLD FRONTAL BOUNDARY. THIS MAY LEAD TO MORE
UPSHEAR AND ELEVATED CONVECTION ALONG THE FRONT AS IT CONTINUES TO
MOVE EASTWARD INTO SOUTHEAST IL...WEST KENTUCKY AND SOUTHWEST
INDIANA WITH THE MOIST AND SLIGHTLY UNSTABLE AIR MASS. THIS MAY
LIMIT WIND AND SOME HAIL POTENTIAL LATE THIS EVENING IN THESE AREAS.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT)
ISSUED AT 157 PM CDT FRI SEP 21 2012
SURFACE LOW IN NE MO...WARM FRONT HAVING ADVANCED ACROSS PAH FA IS
TO OUR NORTH...PM CONVECTION STARTING TO FIRE IN ISOLATED FASHION
NEAR LOW CENTER/ALONG WARM FRONTAL BOUNDARY CENTRAL IL. THIS AREA
BEING CLOSELY MONITORED BY SPC FOR WW...HAIL WOULD BE MAIN THREAT
GIVEN ELEVATED NATURE AND COOLER TEMPS ALOFT.
MODELS THRUST COLD FRONT ACROSS PAH FA THIS EVENING. CONVECTIVE
CHANCES ATTENDANT...BEST NORTHEAST...WILL EXPIRE AFT 06Z WITH
FROPA. UNTIL THEN...GUSTY SSWLYS ESP WHERE CLOUDS HAVE CLEARED
THIS PM WITH GUSTS INTO THE MID 20S KTS. AFTER FROPA INTO
TMRW...WINDS SHIFTING AND ULTIMATELY GUSTY NWLYS BY TMRW PM IN
TIGHT GRADIENT AS SURFACE HIGH WORKS INTO UPPER MS VALLEY.
COOLER/DRIER AIR INFILTRATES THEN FOR THE WEEKEND WITH HIGH
PRESSURE IN CONTROL. U30S POSSIBLE SAT NITE AND SUN NITE MAINLY
NORTH.
.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 157 PM CDT FRI SEP 21 2012
BY MONDAY...THE CENTER OF HIGH PRESSURE WILL BE STARTING TO MOVE
EAST OF THE REGION...AND BECOME SITUATED OVER THE APPALACHIANS BY
00Z TUESDAY. MEANWHILE...SFC WINDS WILL BE VEERING AROUND THE
SOUTH/SOUTHEAST THROUGHOUT THE DAY. MODELS HAVE BEEN ADVERTISING FOR
DAYS NOW...OF PRECIPITATION BREAKING OUT TO OUR WEST...ALONG THE
NOSE OF THE THETA E RIDGE/DEVELOPING WARM FRONT MAINLY ACROSS
MISSOURI...BUT BELIEVE THE MAJORITY OF THE RAIN SHOULD STAY WEST OF
OUR COUNTIES.
HOWEVER...ON MONDAY NIGHT...BOTH THE GFS AND ECMWF SHOW A WEAK
SHORTWAVE IN THE UPPER FLOW THAT MIGHT ACT TO ENHANCE OUR CHANCES
FOR RAIN. THE GFS WEAKENS THIS FEATURE AS IT MOVES IN OUR DIRECTION
AND BOTH THE 06Z AND 12Z RUNS KEEP THE BEST QPF JUST WEST OF OUR
AREA...BUT HINT THAT OUR WESTERN COUNTIES WOULD HAVE THE BEST
CHANCES. THE 00Z ECMWF FAVORS OUR NORTHERN HALF FOR
PRECIPITATION...ESPECIALLY AFTER 06Z...AS IT TAKES THE SHORTWAVE
ACROSS SOUTHERN IL/SOUTHWEST IN.
TUESDAY WILL BE A TRICKY DAY AS THE GFS JUST SHIFTS THE MAIN PRECIP
FOCUS TO OUR NORTH THROUGHOUT THE DAY. THE ECMWF HAS SOME LINGERING
PRECIP IN THE MORNING WITH THE DEPARTING SHORTWAVE AND THEN MAINLY
DRY THE REST OF THE DAY. WE MIGHT END UP JUST BEING WARM SECTORED.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...BOTH THE GFS AND ECMWF
INDICATE MOST OF THE ACTION WILL BE ALONG A FRONTAL BOUNDARY TO OUR
NORTH. SOME OF THOSE SHOWERS/STORMS MAY BLEED INTO OUR NORTHERN
COUNTIES AS THE FRONT SLOWLY SAGS SOUTH...WHICH IS SUPPORTED BY THE
GFS ENSEMBLES. THIS IDEA IS REFLECTED IN THE GOING ZONES...BUT MAY
HAVE TO PULL POPS BACK A BIT GIVEN HOW FAR NORTH THE FRONT IS. THE
I-64 CORRIDOR LOOKS TO BE A GOOD BET RIGHT NOW.
THURSDAY AND BEYOND...THE FORECAST BECOMES EVEN MORE CHALLENGING.
THE GFS AND ECMWF HAVE BEEN SHOWING A LARGE TROUGH ROTATING DOWN
ACROSS THE GREAT LAKES AND UPPER MIDWEST BY TUESDAY NIGHT AND INTO
WEDNESDAY. THE PROBLEM LIES IN THE FACT THAT THE 12Z GFS DOES NOT
CARVE THIS TROUGH AS FAR SOUTH INTO OUR AREA...THEREFORE...THE ZONAL
UPPER FLOW REMAINS IN PLACE AND THE SFC FRONT MOVES SLOWLY SOUTH AND
THEN STALLS DURING THE WEDNESDAY NIGHT THROUGH FRIDAY TIME FRAME.
THE COLD CANADIAN HIGH THAT TRIES TO PRESS DOWN JUST GETS CAUGHT UP
IN THE GREAT LAKES REGION WITH NO WHERE TO GO.
THE 00Z ECMWF SHOWS A MUCH DEEPER TROUGH AND THE UPPER FLOW
BECOMING MORE WEST/NORTHWESTERLY AND THE FRONT COMES THROUGH THE
AREA SOMETIME ON THURSDAY...AND THE SFC HIGH SETTLES IN FURTHER
SOUTH ACROSS OUR AREA FOR FRIDAY. THEREFORE...TEMPERATURE
DIFFERENCES BTWN THE GFS AND ECMWF ARE RATHER LARGE FOR FRIDAY. WILL
PLAY IT SAFE HERE AND GO WITH VERY LOW POPS FOR THURSDAY-FRIDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1143 PM CDT FRI SEP 21 2012
COLD FRONT CONTINUES TO PASS THROUGH THE WFO PAH FORECAST AREA. AT
THE BEGINNING OF THE PERIOD...THE COLD FRONT WIND SHIFT SHOULD
MOVE PAST KCGI...MAKING IT THROUGH THE REMAINDER OF THE TAF SITES
THROUGH 10Z SATURDAY.
GIVEN THE SPEED OF THE FRONT...REDUCED THE POTENTIAL FOR IFR
CEILINGS AT KEVV...BUT LEFT KOWB WITH A BROKEN IFR CEILING THROUGH
THE 09-14Z TIME FRAME.
BEYOND 14Z-16Z...ALL TAFS HAVE UNRESTRICTED VISIBILITY AND
CEILING...WITH ADJUSTMENTS MADE ONLY FOR WIND DIRECTION/SPEED/WIND GUSTS.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...SMITH
AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
506 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TODAY, BRINGING THE CHANCE OF
SHOWERS ACROSS THE AREA. AN UPPER LEVEL DISTURBANCE WILL PUSH THE
FRONT EAST OF THE AREA BY TONIGHT, USHERING MUCH COOLER AIR INTO THE
AREA FOR SUNDAY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST WV SAT IMAGERY AND RAP MID-LEVEL ANALYSIS INDICATE A
CLOSED 500MB LOW CENTERED NORTH OF THE GREAT LAKES IN ONTARIO. AN
INITIAL, WEAK MID-LEVEL VORT MAX THAT WAS CO-LOCATED WITH A 60KT
925MB JET AND SURFACE LOW WEAKENED AS IT SHIFTED FROM OHIO INTO NW
PA. FURTHER UPSTREAM, A STRONG VORT IS CENTERED ALONG THE
WISCONSIN/MINNESOTA BORDER AND IS SHIFTING INTO THE WESTERN GREAT
LAKES. AT THE SURFACE, A 1006MB LOW HAS SHIFTED INTO WESTERN NY WITH
A FRONTAL BOUNDARY EXTENDING SOUTHWEST OF THIS FEATURE. THE
BOUNDARY EXTENDS FROM FRANKLIN TO PITTSBURGH TO PARKERSBURG, WV.
NUMEROUS SHOWERS CONTINUE TO SLIDE NORTHEASTWARD ALONG THE
BOUNDARY.
TODAY...THE SURFACE LOW WILL CONTINUE TO LIFT NORTH OF THE AREA
WITH ITS ASSOCIATED TROUGH AND FRONTAL BOUNDARY SLIDING
SOUTHEASTWARD ACROSS WESTERN PA AND NORTHERN WV BETWEEN 12Z AND
18Z. THIS WILL ALLOW FOR THE CHANCE OF SHOWERS TO CONTINUE INTO THE
EARLY AFTERNOON. A BRIEF RESPITE IN SHOWERS WILL BE POSSIBLE
ACROSS MUCH OF THE AREA DURING THE LATE MORNING INTO EARLY
AFTERNOON HOURS. THE AFOREMENTIONED UPPER MIDWEST-BASED VORTEX WILL
SWING AROUND THE BASE OF THE TROUGH ACROSS THE OHIO VALLEY,
SERVING TO AMPLIFY THE TROUGH AS IT SLIDES INTO WESTERN PA.
FORCING WITH THIS FEATURE WILL INCREASE POP CHANCES BY AROUND,
WITH LIKELY POPS NORTH OF PITTSBURGH BY 00Z SUNDAY.
TEMP FORECAST IS A BIT CHALLENGING AS SKIES WILL BECOME CLOUDY
TODAY WITH THE COLD FRONT PUSHING INTO THE AREA. AHEAD OF THE
FRONT, WAA WILL OCCUR EARLY IN A SOUTHWESTERLY LOW-LEVEL FLOW.
THIS WILL ALLOW TEMPS IN NORTH-CENTRAL WV AND SOUTHWEST PA TO WARM
INTO THE LOWER 70S EARLY BEFORE SHOWERS MOVE INTO THE AREA AND THE
FRONT COOLS TEMPS BACK INTO THE 60S BY LATE AFTERNOON INTO THE
EVENING.
TONIGHT...THE STRONG VORT ENERGY WILL SLIDE NORTHEAST OF THE AREA
WITH COLD AIR ADVECTION ENSUING AS THE COLD FRONT FINALLY EXITS EAST
OF THE AREA. A MOIST NORTHWESTERLY LOW-LEVEL FLOW WITH CAA SUPPORTS
THE CHANCE OF SHOWERS CONTINUING NORTH OF I-70 OVERNIGHT. TEMPS WILL
DROP OFF QUICKLY OVERNIGHT, WITH LOWS A FEW DEGREES COOLER THAN A
MAV/MET BLEND, COOLING TO THE LOWER TO MID 40S ACROSS THE AREA.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
AN OPERATIONAL MODEL CONSENSUS INDICATES THAT THE MID-LEVEL TROUGH
WILL SHIFT FROM THE GREAT LAKES REGION ON SUNDAY INTO THE UPPER
OHIO VALLEY SUNDAY NIGHT. THE AXIS OF THE TROUGH WILL BE CENTERED
OVER THE AREA BY 12Z MONDAY AND QUICKLY SHIFT EASTWARD ON MONDAY.
COLD AIR ADVECTION WILL BE ONGOING IN THE WAKE OF THE COLD FRONT
ON SUNDAY AND SUNDAY NIGHT. THIS IN COMBINATION WITH LOWERING
500MB HEIGHTS, VORT ENERGY ROTATING AROUND THE TROUGH, AND A MOIST
WEST-NORTHWESTERLY LOW-LEVEL FLOW WILL ALLOW FOR THE CHANCE OF
SHOWERS TO CONTINUE NORTH OF PITTSBURGH THROUGH THE DAY ON SUNDAY.
POPS DIMINISH SUNDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE
WEST. WITH 850MB TEMPS COOLING TO 1-3C AND MOSTLY CLOUDY SKIES,
FORECAST IS CLOSEST TO THE COOLER MAV GUIDANCE WITH TEMPS
STRUGGLING TO MAKE IT TO THE 60 DEGREE MARK ACROSS THE AREA FOR
HIGHS ON SUNDAY. CLEARING FROM THE WEST ALONG WITH NEAR CALM WINDS
WILL AID IN RADIATIONAL COOLING SUNDAY NIGHT. LOWS WILL BE AROUND
10 DEGREES BELOW NORMAL. PATCHY FROST IS FORECAST TO DEVELOP NEAR
DAWN ACROSS THE EASTERN RIDGES AND A FROST ADVISORY MAY BE NEEDED
FOR THIS PERIOD.
HIGH PRESSURE WILL SHIFT FROM THE OHIO VALLEY INTO THE MID-
ATLANTIC MONDAY INTO EARLY TUESDAY, ALLOWING FOR A DRY FORECAST
THROUGH THIS PERIOD. SCHC POPS ARE INTRODUCED LATE ON TUESDAY AS
MOISTURE INCREASES AHEAD OF THE NEXT COLD FRONT. ECMWF IS A LITTLE
FASTER WITH PRECIP THAN THE GFS SO STILL SOME UNCERTAINTY WITH THE
TIMING OF THE ONSET OF ANY SHOWERS. DESPITE MORE ABUNDANT SUNSHINE
ON MONDAY, WITH THE COOL, CANADIAN AIR MASS SETTLED INTO THE AREA,
HIGHS WILL BE AROUND 10 DEGREES BELOW NORMAL. TEMPS WILL MODERATE
CLOSER TO SEASONAL NORMALS ON TUESDAY AS THE LOWER-LEVEL FLOW
SHIFTS TO MORE SOUTHERLY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
THE DETERMINISTIC MODELS THEN HAVE A SHORTWAVE DIGGING SOUTHWARD
OVER THE GREAT LAKES. THE GFS IS FASTER THAN THE ECMWF BUT HAS
SLOWED IN THE 12Z RUN. WITH THIS...OPTED TO TAKE A BLEND OF THE
00Z ECMWF/12Z GFS... WHICH SHOWS PRECIPITATION WITH THE FRONT
LATER WEDNESDAY THROUGH THURSDAY. ONCE THE FRONT CROSSES...HIGH
PRESSURE LOOKS TO BUILD OVER MUCH OF THE GREAT LAKES/MIDWEST.
COOL TEMPERATURES ALOFT WITH THE TROUGH SITUATED OVER CANADA WILL
HELP TO KEEP TEMPERATURES AROUND NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
A COUPLE OF SYSTEMS ARE PINWHEELING AROUND A LARGE SCALE UPPER
TROUGH THAT IS NOW RESIDENT OVER THE GREAT LAKES. THE FIRST OF
THESE WILL DRAG A WEAK COLD FRONT ACROSS PART OF THE AREA
THIS MORNING...GRADUALLY TURNING THE WIND MORE WESTERLY OUTSIDE
OF OUTFLOW THAT WILL TURN SOME SITES BRIEFLY NORTHWEST.
OTHERWISE...LOW CLOUDS WILL BECOME MORE COMMON AS DEEPER MOISTURE
MOVES OVER THE TERMINALS. RAINFALL WILL CONTINUE INTO THE EARLY
MORNING HOURS...PARTICULARLY NW OF KPIT.
THE NEXT SYSTEM WILL SWING A COLD FRONT THROUGH THE AREA THIS
EVENING...BRINGING A BETTER CHANCE OF SHOWERS AT ALL SITES AND A
WIND SHIFT TO THE NORTHWEST.
.OUTLOOK /SATURDAY NIGHT THROUGH WEDNESDAY/...
SECONDARY COLD FRONT WILL CONTINUE THE POSSIBILITY OF RESTRICTIONS
THROUGH SUNDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION ON MONDAY
AND TUESDAY WITH VFR CONDITIONS. NEXT FRONTAL SYSTEM APPROACHES THE
AREA ON WEDNESDAY WITH POSSIBLE RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
SHORT TERM...WOODRUM
LONG TERM...
AVIATION...FRIES
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
243 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TODAY, BRINGING THE CHANCE OF
SHOWERS ACROSS THE AREA. AN UPPER LEVEL DISTURBANCE WILL PUSH THE
FRONT EAST OF THE AREA BY TONIGHT, USHERING MUCH COOLER AIR INTO THE
AREA FOR SUNDAY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST WV SAT IMAGERY AND RAP MID-LEVEL ANALYSIS INDICATE A
CLOSED LOW CENTERED NORTH OF THE GREAT LAKES IN ONTARIO. AN INITIAL,
WEAK MID-LEVEL VORT MAX THAT WAS CO-LOCATED WITH A 60KT 925MB JET
AND SURFACE LOW WEAKENED AS IT SHIFTED FROM OHIO INTO NW PA. FURTHER
UPSTREAM, A STRONG VORT IS CENTERED ALONG THE WISCONSIN/MINNESOTA
BORDER AND IS SHIFTING INTO THE WESTERN GREAT LAKES. AT THE SURFACE, A
1006MB LOW IS CENTERED IN CENTRAL OHIO WITH THE FRONTAL BOUNDARY
EXTENDING SOUTHWEST AND TO THE NORTHEAST OF OF THIS FEATURE.
THE BOUNDARY EXTENDS FROM ZANESVILLE TO NEW CASTLE TO FRANKLIN.
NUMEROUS SHOWERS CONTINUE TO SLIDE NORTHEASTWARD ALONG THE
BOUNDARY.
TODAY...THE SURFACE LOW WILL QUICKLY LIFT NORTH OF THE AREA WITH ITS
ASSOCIATED TROUGH AND FRONTAL BOUNDARY SLIDING SOUTHEASTWARD ACROSS
WESTERN PA AND NORTHERN WV BETWEEN 12Z AND 18Z. THIS WILL ALLOW
FOR THE CHANCE OF SHOWERS CONTINUING INTO THE EARLY AFTERNOON. A
BRIEF RESPITE IN SHOWERS WILL BE POSSIBLE ACROSS MUCH OF THE AREA
DURING THE EARLY AFTERNOON HOURS. THE AFOREMENTIONED UPPER
MIDWEST-BASED VORT WILL SWING AROUND THE BASE OF THE TROUGH ACROSS
THE OHIO VALLEY, SERVING TO AMPLIFY THE TROUGH AS IT SLIDES INTO
WESTERN PA. FORCING WITH THIS FEATURE WILL INCREASE POP CHANCES BY
AROUND, WITH LIKELY POPS NORTH OF PITTSBURGH BY 00Z SUNDAY.
TEMP FORECAST IS A BIT CHALLENGING AS SKIES WILL BE
BECOMING CLOUDY TODAY WITH THE COLD FRONT PUSHING INTO THE AREA.
AHEAD OF THE FRONT, WEAK WAA WILL OCCUR EARLY IN A SOUTHWESTERLY
LOW-LEVEL FLOW. THIS WILL ALLOW TEMPS IN NORTH-CENTRAL WV AND
SOUTHWEST PA TO WARM INTO THE LOWER 70S EARLY BEFORE SHOWERS MOVE
INTO THE AREA AND THE FRONT COOLS TEMPS BACK INTO THE 60S BY LATE
AFTERNOON INTO THE EVENING.
TONIGHT...THE STRONG VORT ENERGY WILL SLIDE NORTHEAST OF THE AREA
WITH COLD AIR ADVECTION ENSUING AS THE COLD FRONT FINALLY EXITS EAST
OF THE AREA. A MOIST NORTHWESTERLY LOW-LEVEL FLOW WITH CAA SUPPORTS
THE CHANCE OF SHOWERS CONTINUING NORTH OF I-70 OVERNIGHT. TEMPS WILL
DROP OFF QUICKLY OVERNIGHT, WITH LOWS A FEW DEGREES COOLER THAN A
MAV/MET BLEND, COOLING TO THE LOWER TO MID 40S ACROSS THE AREA.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
MODELS IN FAIR AGREEMENT ON DEEP CLOSED LOW OVER EASTERN CANADA
INTO EARLY NEXT WEEK WITH NEXT SHORTWAVE TO PASS THE EASTERN
GREAT LAKES SATURDAY NIGHT...FOLLOWED BY COLD NORTHWEST FLOW
SUNDAY.
THIS COLD POOL OF AIR ALOFT WILL GENERATE INSTABILITY SHOWERS WITH
LARGER COVERAGE NORTH OF PITTSBURGH SATURDAY NIGHT INTO SUNDAY.
WITH 850MB TEMPERATURES FORECAST TO NEAR 0 DEGREE C SUNDAY NIGHT
MOVING ACROSS WARM LAKES EXPECT SHOWERS TO PERSIST NORTH OF I-80
CORRIDOR UNTIL FLOW SHIFTS LATER SUNDAY NIGHT.
SURFACE HIGH WILL BUILD INTO REGION MONDAY FOR A COOL BUT DRY
DAY.
GFS AND NAM MOS VALUES...SUGGESTING TEMPERATURES CAN BE 10
DEGREES COOLER THAN NORMAL SUNDAY AND SUNDAY NIGHT..SEEM
REALISTIC...BASED ON FORECASTED 850MB TEMPERATURES. WHERE SKY IS
ABLE TO CLEAR SUNDAY NIGHT FROST WILL BE LIKELY IN SHELTERED
LOCATIONS.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
MODELS ARE IN DECENT AGREEMENT TO START THE PERIOD AS AN UPPER LEVEL
TROUGH REMAINS SITUATED OVER THE HUDSON BAY. AT THE SURFACE...HIGH
PRESSURE WILL KEEP THE UPPER OHIO VALLEY DRY THROUGH WEDNESDAY.
THE DETERMINISTIC MODELS THEN HAVE A SHORTWAVE DIGGING SOUTHWARD
OVER THE GREAT LAKES. THE GFS IS FASTER THAN THE ECMWF BUT HAS
SLOWED IN THE 12Z RUN. WITH THIS...OPTED TO TAKE A BLEND OF THE
00Z ECMWF/12Z GFS... WHICH SHOWS PRECIPITATION WITH THE FRONT LATER
WEDNESDAY THROUGH THURSDAY. ONCE THE FRONT CROSSES...HIGH PRESSURE
LOOKS TO BUILD OVER MUCH OF THE GREAT LAKES/MIDWEST.
COOL TEMPERATURES ALOFT WITH THE TROUGH SITUATED OVER CANADA WILL
HELP TO KEEP TEMPERATURES AROUND NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
A COUPLE OF SYSTEMS ARE PINWHEELING AROUND A LARGE SCALE UPPER
TROUGH THAT IS NOW RESIDENT OVER THE GREAT LAKES. THE FIRST OF
THESE WILL DRAG A WEAK COLD FRONT ACROSS PART OF THE AREA
THIS MORNING...GRADUALLY TURNING THE WIND MORE WESTERLY OUTSIDE
OF OUTFLOW THAT WILL TURN SOME SITES BRIEFLY NORTHWEST.
OTHERWISE...LOW CLOUDS WILL BECOME MORE COMMON AS DEEPER MOISTURE
MOVES OVER THE TERMINALS. RAINFALL WILL CONTINUE INTO THE EARLY
MORNING HOURS...PARTICULARLY NW OF KPIT.
THE NEXT SYSTEM WILL SWING A COLD FRONT THROUGH THE AREA THIS
EVENING...BRINGING A BETTER CHANCE OF SHOWERS AT ALL SITES AND A
WIND SHIFT TO THE NORTHWEST.
.OUTLOOK /SATURDAY NIGHT THROUGH WEDNESDAY/...
SECONDARY COLD FRONT WILL CONTINUE THE POSSIBILITY OF RESTRICTIONS
THROUGH SUNDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION ON MONDAY
AND TUESDAY WITH VFR CONDITIONS. NEXT FRONTAL SYSTEM APPROACHES THE
AREA ON WEDNESDAY WITH POSSIBLE RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
526 AM EDT SAT SEP 22 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 525 AM EDT SAT SEP 22 2012
1004MB SFC LOW IS CURRENTLY JUST TO THE EAST OF LK SUPERIOR AND
LOCATED ON THE EASTERN EDGE OF THE PERSISTENT UPPER TROUGH THAT HAS
BEEN OVER THE UPPER GREAT LAKES REGION. THERE ARE A COUPLE
SHORTWAVES OF NOTE THAT WILL BE AFFECTING THE AREA TODAY AND
TONIGHT. THE FIRST WAVE IS LOCATED OVER NW WI AND DROPPING TO THE
SE. THIS HAS PRODUCED SCATTERED SHOWERS OVER FAR WESTERN UPPER
MICHIGAN AND LK SUPERIOR. AS THIS SHORTWAVE HAS STARTED TO SLIDE TO
THE S...A SFC TROUGH STRETCHING E TO W ACROSS SRN LK SUPERIOR HAS
ALSO BEEN SLIDING S AND HELPED PRODUCE A FEW SHOWERS AND AN ISOLATED
THUNDERSTORM. WINDS ARE QUICKLY TURNING TO THE N AND GUSTING TO
25KTS BEHIND THIS TROUGH. THE OTHER SHORTWAVE IS LOCATED OVER NW
ONTARIO AND QUICKLY DROPPING SOUTH.
TODAY...SHORTWAVE DIVING SE THROUGH WI THIS MORNING HAS STARTED TO
USHER IN COLDER H850 TEMPS OVER THE AREA TODAY...WITH RUC ANALYZED
VALUES FALLING FROM AROUND 0 TO -1C AT 00Z TODAY TO -2 TO -3C AT
08Z. THESE COOLER TEMPS ALOFT AND ADDITIONAL MOISTURE BEHIND THE
FIRST SHORTWAVE MOVING THROUGH NW WI THIS MORNING WILL LEAD TO AN
UPTICK IN LK ENHANCED SHOWERS THIS MORNING...ESPECIALLY ALONG AND
RIGHT BEHIND THE SFC TROUGH. BUT A POCKET OF DRIER H850-700 MOISTURE
OVER THE WESTERN CWA SHOULD KEEP THE SHOWERS OVER THE WEST FROM
BECOMING TOO WIDESPREAD AND STRONG. THEY MAY EVEN END DURING THE
LATE MORNING AND EARLY AFTERNOON...AS THERE IS LIMITED MOISTURE SEEN
TOWARDS THUNDER BAY AND SRN ONTARIO. MODELS ARE SHOWING ENOUGH
SHALLOW MOISTURE TO SUPPORT AT LEAST LK ENHANCED CLOUDS DURING THAT
DRIER PERIOD. FARTHER EAST...DEEPER MOISTURE IS IN PLACE UNDER THE
UPPER TROUGH AND WITH THE COLD AIR ALOFT...EXPECT LK ENHANCED
SHOWERS TO BECOME MORE WIDESPREAD THROUGH THE DAY. THEN AS THE
SECONDARY SHORTWAVE...CURRENTLY IN NW ONTARIO...ARRIVES IN THE
MID-LATE AFTN AND CONTINUES INTO THE EVENING WITH THE CONTINUED
COOLING ALOFT...EXPECT LK ENHANCED SHOWERS AIDED BY THE SHORTWAVE TO
REALLY TAKE OFF ACROSS ALL BUT THE SCNTRL CWA.
THE BIGGEST ISSUE FOR TODAY MAY BE POTENTIAL FOR THUNDER AND
GRAUPEL. THE COLD AIR ALOFT WILL HELP STEEPEN LLVL LAPSE RATES AND
LEAD TO STRONGER UPDRAFTS. BUFKIT LK INDUCED CAPE VALUES HAVE BEEN
FAIRLY IMPRESSIVE...500-1250 J/KG...BUT MODIFYING SOUNDINGS TO LOW
50S OVER LOW-MID 40S WOULD INDICATE CAPES STAYING IN THE 300-500
J/KG RANGE. OVER THE LAST COUPLE DAYS IT SEEMS THE LIGHTNING HAS
OCCURRED WHERE ADDITIONAL FORCING HAS BEEN PRESENT
/E.G. SHORTWAVE...CONVERGENCE ALONG FRONT/. THUS...EXPECT A
LULL IN THUNDER CHANCES AFTER THE TROUGH MOVES THROUGH AND
THEN REDEVELOP TOWARDS AFTN WHEN SHORTWAVE ARRIVES AND PEAK HEATING
IS HERE. AS FOR GRAUPEL...WILL CONTINUE TO MENTION POTENTIAL WITH
THE STRENGTH OF THE UPDRAFTS. PUSHED THE PROBABILITIES UP HEADING
INTO THE AFTN WITH THE APPROACHING SHORTWAVE AND DEEPER MOISTURE.
AS FOR WINDS...H950-850 WINDS ARE GENERALLY IN THE 30-35KT
RANGE...SO EXPECT GALES TO 35-37KTS TO BE THE NORM. THINKING WITH
LITTLE VARIABILITY IN THE WINDS IN THAT LAYER AND THE STRONG
PRESSURE GRADIENT...IT WILL LIKELY BE SUSTAINED WINDS TOWARDS
25-30KTS AND THEN GUSTS TOWARDS THAT 35KT RANGE. WITH LITTLE
ADDITIONAL SUPPORT FROM ISALLOBARIC FEATURES...DON/T EXPECT THE
GUSTS TO GET MUCH HIGHER THAN THE MODELS ARE SHOWING OVER ERN LK
SUPERIOR AND SHOULDN/T REACH ADVY CRITERIA NEAR THE LAKESHORE OVER
ALGER/LUCE COUNTIES.
TONIGHT...TIGHT PRESSURE GRADIENT WILL SHIFT SE OF THE CWA...AS HIGH
PRESSURE OVER THE NRN PLAINS BEGINS TO SLOWLY APPROACH THE AREA. THE
SHORTWAVE THAT ARRIVES OVER THE NW HALF OF THE CWA IN THE AFTN WILL
PUSH THROUGH THE CWA DURING THE EVENING HOURS. WILL KEEP HIGHER
POPS OVER LOCATIONS NEAR LAKE SUPERIOR DURING THE EVENING HOURS
DUE TO LK ENHANCEMENT. AS THE SHORTWAVE MOVES SE OF THE CWA...EXPECT
A TRANSITION TO JUST LK ENHANCED SHOWERS WITH H850 TEMPS AROUND -3
TO -4C. DRYING ALOFT FROM THE HIGH WILL ALLOW THE LK ENHANCED
SHOWERS TO BECOME FOCUSED FARTHER EAST WHERE THE DEEPEST MOISTURE
REMAINS THROUGH THE NIGHT. STILL THINK THERE WILL BE ENOUGH
MOISTURE FOR SCATTERED SHOWERS OUT WEST WITH THE SHORTER FETCH.
COULD BE SOME DECENT RAINS OVER THE ERN CWA DEPENDING ON WHERE THE
SHOWERS LINE UP. APPEARS TO BE SOME ENHANCED CONVERGENCE IN THAT
AREA WITH THE APPROACHING HIGH...NNW OVER THE FAR ERN LK AND
BACKING TO THE NW-WNW OVERNIGHT OVER WRN LK SUPERIOR. WITH THE
VERY DEEP CLOUD/CONVECTIVE LAYER...COULD EASILY SEE AREAS TOWARDS
MUNISING ENDING UP WITH OVER AN INCH OF RAIN BY SUNDAY MORNING.
WILL LEAVE A SLIGHT CHANCE MENTION OF SNOW IN OVER THE
WRN CWA...BUT MODEL SOUNDING PROFILES SHOW A COUPLE FEATURES
LIMITING POTENTIAL. FIRST...BEST LLVL FORCING COINSIDING WITH THE
CLOUD LAYER IS IN THE -1 TO -5C TEMP RANGE...WHICH LIMITS ICE IN
THE CLOUD. SECOND...WBZ VALUES IN THE 1200-1500 FT RANGE WOULD
INDICATE ONLY A LOW POTENTIAL FOR SNOW TO MAKE IT TO THE SFC IF
THERE IS ACTUALLY ICE/SNOW PRESENT IN THE CLOUD. BUT IF GFS
SOUNDINGS ARE CORRECT WITH A SLIGHTLY COLDER AND DEEPER CLOUD
DEPTH...SNOW WOULD BE MORE LIKELY.
AS FOR WATERSPOUTS OVER THE LAKES TODAY AND TONIGHT...SWI INDICATES
VERY FAVORABLE CONDITIONS...APPROACHING 7-9...DUE TO DEEP CONVECTIVE
LAYER AND SFC-850 DELTA-T VALUES AROUND 15-17. THE ONLY DRAWBACK IS
THE STRONG WINDS THIS AFTN. WITH H850 WINDS AROUND 30-35KTS...THIS
IS ON THE HIGH END FOR WATERSPOUT POTENTIAL THROUGH THE DAY TODAY.
IF WINDS END UP A LITTLE LOWER THAN EXPECTED...COULD SEE POTENTIAL
INCREASE. WITH WINDS DECREASING TONIGHT...HAVE ADDED THE POTENTIAL
BACK OVER THE ERN HALF OF LK SUPERIOR...ESPECIALLY WITH THE ADDED
CONVERGENCE AND EXPECTED AREA OF STRONGER SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 525 AM EDT SAT SEP 22 2012
MEDIUM RANGE GUIDANCE IS IN GENERAL AGREEMENT ON THE BIG PICTURE
OVER THE NEXT 7 DAYS. CURRENT COOL PATTERN FOR UPPER MI WILL PEAK
TODAY/SUN AS TROF REACHES PEAK AMPLITUDE. COOL WEATHER WILL CONTINUE
INTO THE EARLY PART OF THE UPCOMING WEEK AS RIDGE REMAINS OVER WRN
NAMERICA WITH DOWNSTREAM TROF EXTENDING S THRU THE GREAT LAKES...
THOUGH THERE WILL BE A SHARP WARM UP MON AHEAD OF THE NEXT SHORTWAVE
DROPPING INTO THE TROF. INTO THE MIDDLE/END OF THE WEEK...TROF WILL
WEAKEN/LIFT OUT AS UPSTREAM RIDGE DEAMPLIFIES SOME AND PROGRESSES
E...BUT IT APPEARS MORE ENERGY MAY DROP SE INTO THE NE CONUS LATE
WEEK...PREVENTING A MORE SUSTAINED WARMING TREND FROM TAKING HOLD
HERE. HOWEVER...TEMPS WILL STILL RETURN TO MORE TYPICAL LATE SEPT
VALUES. PCPN CHANCES WILL BE HIGHEST TODAY/SUN UNDER THE DEEP TROF
OVER THE AREA. TREND WILL THEN BE TOWARD DRY WEATHER DURING THE
UPCOMING WEEK AS TROF GRADUALLY WEAKENS/DRIFTS E.
BEGINNING SUN...MID/UPPER TROF WILL BEGIN TO SHIFT E...RESULTING IN
SLOWLY RISING HEIGHTS. AT THE LOWER LEVELS...THE UPPER LAKES WILL
REMAIN FIRMLY IN THE THERMAL TROF WITH MODERATION ONLY APPEARING TO
OCCUR DUE TO DAYTIME HEATING. WITH MORNING 850MB TEMPS OF -1 TO -4C
ONLY RISING TO 0 TO -2 BY THE END OF THE AFTN...LAKE EFFECT -SHRA
WILL CONTINUE THRU THE DAY. HOWEVER...RISING HEIGHTS ALONG WITH
ADVECTION OF DRIER AIR AT THE LOW LEVELS AS WINDS BACK MORE W SHOULD
SPELL DIMINISHING SHRA FROM W TO E THRU THE DAY. BEING VERY EARLY IN
THE LAKE EFFECT SEASON...DIURNAL HEATING WILL ALSO DISRUPT LAKE
EFFECT PROCESSES...AIDING THE DIMINISHING TREND. SO...EXPECT
LINGERING NW FLOW LAKE EFFECT SHRA OVER THE W TO END BY EARLY/MID
AFTN. OVER THE E...LAKE EFFECT SHRA WILL DECREASE IN COVERAGE...BUT
NOT LIKELY END UNTIL LATER SUN EVENING WHEN WINDS BACK TO AN
OFFSHORE DIRECTION. WITH DIURNAL MIN SUN MORNING...1000-850MB
THICKNESS BTWN 1305-1310M OVER THE W SUGGEST SOME POTENTIAL FOR SNOW
FLAKES TO MIX WITH THE SHRA OVER THE HIGH TERRAIN. OTHERWISE...
GRAUPEL WILL CONTINUE TO BE THE MAIN FROZEN PTYPE THAT WILL MIX WITH
THE HEAVIER SHRA.
WAA REGIME RAMPS UP ON WESTERLY WINDS SUN NIGHT/MON AHEAD OF THE
NEXT SHORTWAVE TROF WHICH WILL BE DROPPING TOWARD THE UPPER LAKES.
WITH DEPARTURE OF LAKE EFFECT CLOUDS AND BEFORE HIGH CLOUDS ARRIVE
AHEAD OF APPRAOCHING SHORTWAVE AND BEFORE LOW-LEVEL WINDS INCREASE
SUBSTANTIALLY...TEMPS WILL HAVE AN OPPORTUNITY TO FALL QUICKLY UNDER
DRY AIR MASS (PRECIPITABLE WATER 50-60PCT OF NORMAL). FAVORED THE
LOWER SIDE OF GUIDANCE GIVEN THE COOL AFTN SUN. TEMPS WILL PROBABLY
SLIP BLO FREEZING IN MANY INTERIOR LOCATIONS. TIGHT PRES GRADIENT
BTWN SFC HIGH OVER THE OHIO VALLEY AND COLD FRONT DROPPING TOWARD
THE AREA MON WILL LEAD TO A BREEZY/WINDY DAY. 850MB WINDS ARE
PROGGED AT 40-45KT (TO NEAR 50KT ON NAM). EXAMINATION OF FCST
SOUNDINGS SUGGEST MIXED LAYER WILL BUILD SUFFICIENTLY TO TAP SOME OF
THE STRONGER WINDS. GUSTS OF 30-35MPH WILL PROBABLY BE COMMON...BUT
IF THE DAY ENDS UP WITH LESS CLOUDINESS/HIGHER MIXING HEIGHT...COULD
BE TALKING A WIND ADVY TYPE DAY. GIVEN THE DRY ANTECEDENT AIR MASS
AND LACK OF A LOW-LEVEL MOISTURE CONNECTION...SHRA SEEM UNLIKELY
AHEAD OF COLD FRONT. FOR NOW...PLAN TO STAY WITH JUST SLIGHT CHC
POPS OVER THE ERN FCST AREA...CLOSER TO STRONGER DEEP LAYER FORCING.
MAY END UP WITH JUST SOME SPRINKLES IF ANY PCPN DOES OCCUR.
LOW-LEVEL JET TRANSLATING ACROSS THE AREA WILL BRING STRONG WARMING
AS 850MB TEMPS SURGE TO 6-9C BY THE END OF THE AFTN. 60S SHOULD
GENERALLY BE THE RULE FOR MAX TEMPS.
COLD FRONT DROPS THRU THE AREA MON NIGHT. NOT EXPECTING MUCH IF ANY
LAKE EFFECT PCPN BEHIND FRONT UNDER MARGINALLY COLD AIR MASS AS
ANTICYCLONIC FLOW QUICKLY TAKES OVER AFTER FROPA. UNDER N WINDS...
MIGHT SEE A FEW -SHRA IN THE UPSLOPE AREAS NEAR LAKE SUPERIOR MON
NIGHT. DRY WEATHER SHOULD THEN DOMINATE TUE THRU THU AS SFC HIGH
PRES SLOWLY MOVES ACROSS THE UPPER GREAT LAKES. ONE EXCEPTION MAY BE
TUE NIGHT. 850MB TEMPS FALLING TO AROUND -2C MAY ALLOW SOME LAKE
EFFECT -SHRA TO DEVELOP. IN THE INTERIOR...SHOULD SEE A COUPLE OF
COLD NIGHTS (FREEZES) TUE NIGHT/WED NIGHT AS WINDS DIMINISH TO LIGHT
WITH SFC HIGH IN THE VCNTY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 135 AM EDT SAT SEP 22 2012
IWD IS EXPERIENCING SOME RAIN SHOWERS NEARBY FROM A SHORTWAVE
SKIRTING THE AREA...BUT ELSEWHERE SKIES ARE PARTLY CLOUDY TO MOSTLY
CLEAR AT SAW AND CMX. AS COLDER AIR MOVES MOVES IN ALOFT TONIGHT AND
SATURDAY...WINDS WILL BECOME MORE NORTHERLY AND A SHORTWAVE WILL MOVE
IN FROM THE NORTH. AS THIS HAPPENS CONDITIONS WILL DECLINE
QUICKLY...BUT IT IS UNCERTAIN AS TO THE EXTENT OF THE LOW CLOUDS
GIVEN MODEL VARIABILITY. KEPT CIGS AT MVFR AT THE LOWEST...WHICH
LOOKS FAIRLY SAFE TO SAY GIVEN UPSTREAM OBS...BUT THERE IS A CHANCE
CIGS COULD DROP INTO THE IFR CATEGORY DUE TO LAKE ENHANCEMENT. IT
APPEARS CONDITIONS WILL BE WORST AT SAW DUE TO MORE EXPOSURE FROM N
WINDS. WINDS WILL PICK UP ON SATURDAY...HIGHEST AT SAW AND CMX.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 525 AM EDT SAT SEP 22 2012
NORTH TO NORTHWEST GALES TO 35-40KTS ARE EXPECTED TODAY OVER THE
EASTERN HALF OF LAKE SUPERIOR AND CONTINUE INTO TONIGHT. AS HIGH
PRESSURE OVER THE NORTHERN PLAINS BEGINS TO WORK IN TONIGHT...EXPECT
THE WINDS TO SLOWLY DIMINISH. THERE IS A POTENTIAL FOR WATERSPOUTS
TODAY AND TONIGHT...ALTHOUGH THE BEST CHANCE WILL COME TONIGHT AS
THE WINDS DECREASE SOME. A SECONDARY TROUGH DROPPING SOUTHEAST
ACROSS LAKE SUPERIOR MONDAY NIGHT WILL BRING ANOTHER PERIOD OF
GALES. SOUTHWEST WINDS AHEAD OF THIS FRONT SHOULD REACH GALES TO
35KTS BY LATE SUNDAY NIGHT AND CONTINUE INTO MONDAY UNTIL THE TROUGH
MOVES THROUGH. BEHIND THE TROUGH...HIGH PRESSURE WILL SETTLE OVER
THE UPPER GREAT LAKES REGION FOR TUESDAY AND WEDNESDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 11 AM THIS MORNING TO 11 PM EDT THIS EVENING
FOR LSZ251-267.
GALE WARNING UNTIL 1 AM EDT SUNDAY FOR LSZ244-245-248>250-
264>266.
GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...TITUS
MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
137 AM EDT SAT SEP 22 2012
.SHORT TERM...(THIS EVENING THROUGH SATURDAY)
ISSUED AT 458 PM EDT FRI SEP 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A DEEP MID/UPPER LEVEL TROUGH
FROM HUDSON BAY INTO THE WRN GREAT LAKES. THE SHRTWV THAT BROUGHT AN
AREA OF RAIN AND SOME TSRA TO UPPER MI THIS MORNING HAS MOVED
QUICKLY EAST OF LAKE SUPERIOR. ANOTHER VIGOROUS UPSTREAM SHRTWV/VORT
WAS LOCATED JUST SE OF LAKE WINNIPEG. SOME LIGHTNING HAS ALSO
ACCOMPANIED A LINE OF SHOWERS AHEAD OF THIS FEATURE. AT THE
SFC...LOW PRES WAS LOCATED OVER ERN LAKE SUPERIOR. THE COLD FRONT
ASSOCIATED WITH THE UPSTREAM SHRTWV HAS MOVED INTO THE NW CORNER OF
MN HAS BRINGING VERY GUSTY WINDS TO AROUND 35KT IN ITS WAKE. RADAR
INDICATED SCT SHOWERS LINGERING OVER THE AREA SUPPORTED BY SHALLOW
INSTABILITY AND LAKE MOISTURE AS 850/700 MB TEMPS REMAIN NEAR
0C/-10C.
TONIGHT...EXPECT A BRIEF PERIOD OF MORE LIMITED SHRA COVERAGE THIS
EVENING AS THE LOW LEVEL TROUGH AND BATCH OF SHRA OVER CNTRL UPPER
MI MOVES TO THE EAST. HOWEVER SOME LAKE ENHANCED SHOWERS SHOULD
STILL LINGER NEAR AREAS FAVORED BY NW FLOW. SATELLITED TRENDS AND
MODELS SUGGEST THAT THE MAIN IMPACTS OF THE MANITOBA SHRTWV WILL
SLIDE WELL TO THE WEST AND SOUTH OF UPPER MICHIGAN. HOWEVER...AS IT
MOVES TO THE SOUTH WINDS WILL VEER MORE NRLY AND COLDER AIR WILL
PUSH INTO THE AREA. LAKE EFFECT SHOWERS SHOULD THEN INCREASE FOR N
FLOW AREAS AS 850 MB TEMPS FALL TO AROUND -2C.
SATURDAY...THE BULK OF THE COLDER AIR MOVES IN WITH 850/700 MB TEMPS
FALLING TO AROUND -3C/-12C. NAM FCST SOUNDINGS SUGGEST THAT LAKE
INDUCED CAPE MAY CLIMB INTO THE 500-1000 J/KG RANGE. EXPECT HEAVIEST
PCPN OVER LOCATIONS FAVORED BY NNW FLOW...ESPECIALLY OVER N CNTRL INTO E
UPPER MI. ALTHOUGH LIGHTNING WOULD BE UNUSUAL WITH LAKE EFFECT
PCPN...WITH THE VERY COLD AIR ALOFT (500 MB TEMP TO -30C) CANNOT
RULE OUT SOME ISOLD TSRA AS WAS OBSERVED THIS MORNING. SIMILAR TO
THE LAST FEW DAYS...PERIODS OF GRAUPEL/SLEET MAY ALSO ACCOMPANY THE
HEAVIER SHOWERS. WITH WET-BULB ZERO HEIGHTS DOWN TO NEAR 1500 FT
AGL. SOME SNOW COULD BE POSSIBLE OVER HIGHER TERRAIN BUT WOULD
LIKELY BE VERY TRANSIENT/BRIEF. GALES OVER LAKE SUPERIOR WILL ALSO
BRING SOME STRONGER WINDS TO SHORELINE LOCATIONS POSSIBLY REACHING
ADVY CRITERIA (45 MPH GUSTS) AT THE MOST EXPOSED LOCATIONS.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 458 PM EDT FRI SEP 21 2012
SAT NGT...A HEALTHY LAKE EFFECT/ENHANCED SHRA REGIME WL CONT WITH
DEEP CYC NW FLOW OF CHILLY AIR /H85 TEMPS -3 TO -5C/ UNDER
PERSISTENT SHARP UPR TROF AXIS...ESPECIALLY FOR THOSE AREAS ON THE
CYC SIDE OF TRACK OF SHRTWV THAT IS FCST TO DIG SHARPLY THRU THE NNW
FLOW ALF. GIVEN THE INTENSITY OF THE TROF AND LOCATION OF H3 UPR JET
AXIS THRU MN/WI...PREFER THOSE MODELS THAT SHOW A FARTHER W TRACK
FOR THIS DISTURBANCE. RETAINED MENTION OF TS OVER MAINLY AREAS NEAR
THE E HALF OF LK SUP WHERE NAM SHOW SBCAPE UP TO 300-400 J/KG.
NOT OUT OF THE QUESTION THAT ANY -SHRA OVER THE INTERIOR W COULD MIX
WITH SN OVER THE HIER TERRAIN LATER AT HGT IN PRESENCE OF DIURNAL
COOLING/MIN TEMPS FALLING CLOSE TO 32 AS 12Z NAM SHOWS H100-85 THKNS
AND WBZ HGT FALLING TO 1300-1305M/NEAR 1K FT AGL. WITH MORE OF A
LAKE WARMING INFLUENCE ELSEHWERE...PTYPE WL BE RA...BUT DID RETAIN
MENTION OF MIX WITH SLEET/GRAUPEL FOR AREAS IMPACTED BY SOME HEAVIER
SHRA.
SUN...AS CLOSED LO/CORE OF COLD MID LVL TEMPS LIFTS NEWD INTO
QUEBEC...MODELS SHOW SLOWLY RISING HGTS UNDER LARGER SCALE DNVA/
SINKING INVRN BASE/RISING H85 OVER THE UPR LKS. SINCE THE LLVL FLOW
IS PROGGED TO BACK MORE W AND ADVECT DRIER LLVL AIR INTO THE AREA AS
SFC HI PRES CENTER SINKS TOWARD THE MID MS RIVER VALLEY LATE IN THE
DAY IN THE PRESENCE OF DIURNAL HEATING THAT WL DISRUPT THE LAKE
EFFECT PROCESS...EXPECT STEADILY DCRSG POPS THAT WL LINGER LONGEST
DOWNWIND OF LK SUP E OF MQT WHERE LOWER H85 TEMPS AND LLVL
MOISTENING OF THE DRIER FLOW WL BE MORE PERSISTENT.
SUN NGT...DNVA/LOWERING INVRN BASE AND BACKING/DRYING FLOW TO WSW
BTWN HI PRES MOVING INTO THE OH RIVER VALLEY AND SHRTWV DIGGING SEWD
FM MANITOBA WL CONSPIRE TO FINALLY DIMINISH ANY LINGERING LK EFFECT
PCPN OVER THE E. DESPITE PARTIAL CLEARING BEFORE SOME MID/HI CLDS IN
ADVANCE OF APRCHG SHRTWV ARRIVE...LLVL WARMING/STEADY WSW FLOW THAT
MAINTAINS SOME MIXING WL RESTRICT DIURNAL TEMP FALL DESPITE PWAT
FALLING AS LO AS 0.30 INCH. WHERE THE PRES GRADIENT IS SLOWER TO
TIGHTEN UP AND CLDS ARRIVE LATER NEAR THE WI BORDER...MIN TEMPS MAY
APRCH 32.
MON...SHRTWV EMBEDDED IN NW FLOW ALF ON WRN FLANK OF SLOWLY
RETREATING UPR TROF IS PROGGED TO SWING SEWD THRU ONTARIO. ALTHOUGH
SOME OF THE MORE IMPRESSIVE DVPA/DEEP LYR QVECTOR CNVGC IS PROGGED
TO BRUSH MAINLY THE NE HALF OF THE CWA...DRYNESS OF FCST SDNGS/
ABSENCE OF ANY LLVL MSTR ADVECTION INDICATE ANY SHRA WL BE FEW AND
FAR BTWN. MAINTAINED THEME OF LO CHC POPS OVER PORTIONS OF THE NE
CWA CLOSER TO MORE IMPRESSIVE DYNAMICS. WARMING H85 TEMPS IN STEADY
WSW FLOW AHEAD OF ATTENDANT COLD FNT WL PUSH MAX TEMPS ABV
NORMAL...BUT GUSTY SFC WINDS WL MAKE THE AIR FEEL COOLER. MIXING TO
H85 ON GFS FCST SDNGS INDICATES MAX TEMPS WL RISE INTO THE 60S AT
MOST SPOTS.
MON NGT THRU TUE NGT...AS LO PRES TROF CROSSES THE CWA ON MON NGT
WITH WSHFT TO THE N...WENT WITH LO CHC POPS MAINLY IN THE UPSLOPE
AREAS NEAR LK SUP. THEN TRAILING HI PRES MOVING IN FM CNTRL CAN WL
BRING A PERIOD OF DRY WX ON TUE. BUT AS COOLER AIR /WITH H85 TEMPS
DROPPING AOB 0C/ ARRIVES ON TUE NGT...SOME LK EFFECT PCPN MAY DVLP
MAINLY OVER THE NCNTRL IN AREAS FAVORED BY FCST LLVL NLY FLOW. AWAY
FM THE MODERATING INFLUENCE OF LK SUP AND CLOSER TO INCOMING HI PRES
CENTER BLDG INTO MN...TENDED BLO GUIDANCE FOR MIN TEMPS TOWARD 32
OVER THE INTERIOR W.
EXTENDED...SFC HI PRES IS FCST TO DOMINATE UNDER RISING HGTS AS UPR
TROF IN CAN SLOWLY LIFTS TO THE NE. EXPECT DRY WX THRU THIS PERIOD
WITH WIDE DIURNAL TEMP VARIATIONS...ESPECIALLY OVER THE INTERIOR
AWAY FM THE MODERATING INFLUENCE OF THE LKS. OVERALL HOWEVER...TEMPS
SHOULD AVG BLO NORMAL DURING THIS TIME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 135 AM EDT SAT SEP 22 2012
IWD IS EXPERIENCING SOME RAIN SHOWERS NEARBY FROM A SHORTWAVE
SKIRTING THE AREA...BUT ELSEWHERE SKIES ARE PARTLY CLOUDY TO MOSTLY
CLEAR AT SAW AND CMX. AS COLDER AIR MOVES MOVES IN ALOFT TONIGHT AND
SATURDAY...WINDS WILL BECOME MORE NORTHERLY AND A SHORTWAVE WILL MOVE
IN FROM THE NORTH. AS THIS HAPPENS CONDITIONS WILL DECLINE
QUICKLY...BUT IT IS UNCERTAIN AS TO THE EXTENT OF THE LOW CLOUDS
GIVEN MODEL VARIABILITY. KEPT CIGS AT MVFR AT THE LOWEST...WHICH
LOOKS FAIRLY SAFE TO SAY GIVEN UPSTREAM OBS...BUT THERE IS A CHANCE
CIGS COULD DROP INTO THE IFR CATEGORY DUE TO LAKE ENHANCEMENT. IT
APPEARS CONDITIONS WILL BE WORST AT SAW DUE TO MORE EXPOSURE FROM N
WINDS. WINDS WILL PICK UP ON SATURDAY...HIGHEST AT SAW AND CMX. &&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 458 PM EDT FRI SEP 21 2012
A LAKE ENHANCED LOW OVER ERN LAKE SUPERIOR WILL BE SLOW TO MOVE
OFF LK SUPERIOR TONIGHT WHILE HIGH PRESSURE RIDGE BUILDS FROM SCNTRL
CANADA INTO THE NORTHERN PLAINS. THE PRESSURE GRADIENT WILL TIGHTEN
AND EXPECT NNW WINDS TO INCREASE TO GALES LATE TONIGHT OVER NORTH
CENTRAL SECTIONS OF LK SUPERIOR. THERE IS A RISK OF WATERSPOUTS
TONIGHT...PER NOMOGRAM OUTPUT...AS VERY COLD AIR MOVES OVER THE
RELATIVELY WARM WATER BEFORE THE WINDS INCREASE.
GALES ARE EXPECTED SAT INTO SAT EVENING FOR THE CNTRL AND EAST
PORTIONS OF LAKE SUPERIOR AS THE SFC LOW DEEPENS TO THE E AND COLDER
AIR MOVES OVER THE LAKE...CREATING A VERY UNSTABLE TEMP PROFILE.
EXPECT WINDS ON SAT NIGHT INTO SUN NIGHT TO SLOWLY DIMINISH AND
GRADUALLY BACK TO THE W AS A HI PRES CENTER MOVES FROM THE NORTHERN
PLAINS INTO THE OHIO RIVER VALLEY. ANOTHER ROUND OF WSW GALES IS
POSSIBLE LATE SUN NIGHT INTO MON AS THE PRES GRADIENT TIGHTENS
BETWEEN THE RETREATING HI TO THE SE AND ANOTHER LO PRES TROF
DROPPING SEWD FROM CENTRAL CANADA THRU ONTARIO TOWARD LAKE SUPERIOR.
FOLLOWING THE PASSAGE OF THIS TROF ON MON...WINDS WILL DIMINISH AND
VEER TO THE N AHEAD OF HI PRES APPROACHING FROM THE NW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 2 PM THIS AFTERNOON TO 1 AM EDT SUNDAY FOR
LSZ251-267.
GALE WARNING FROM 6 AM THIS MORNING TO 1 AM EDT SUNDAY FOR
LSZ244-245-248>250-264>266.
GALE WARNING FROM 6 AM THIS MORNING TO 2 PM EDT THIS AFTERNOON
FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...TITUS
MARINE...JLB/KC
AREA FORECAST DISCUSSION...UPDATED
NWS DULUTH MN
1222 AM CDT SAT SEP 22 2012
.AVIATION.../06Z TAF ISSUANCE/
POTENT UPPER LOW WAS DROPPING THROUGH THE NORTHLAND THIS
EVENING...AND WILL CONTINUE SOUTH OVERNIGHT. LIGHT RAIN...MIXED
WITH OR ALL SNOW IN SPOTS OVER NORTHERN MINNESOTA...WILL DIMINISH
OVERNIGHT. MVFR CEILINGS WITH POCKETS OF IFR...WILL BE POSSIBLE
OVERNIGHT INTO SATURDAY MORNING...BEFORE GRADUALLY LIFTING THROUGH
THE DAY. SOME IFR VSBYS WILL ALSO BE POSSIBLE. CEILINGS SHOULD
LIFT TO LOW VFR FOR MOST AREAS BY 18Z. COLD TEMPERATURES ALOFT
SHOULD ALSO LEAD TO A CU DECK SHOULD ANY AREAS CLEAR OUT. THE CU
WILL DIMINISH THOUGH FROM WEST TO EAST LATE IN THE AFTERNOON AND
EVENING. KHYR SHOULD CEILINGS THE LONGEST WITH LAKE INDUCED CLOUDS
STREAMING IN FROM THE NORTH.
&&
.PREV DISCUSSION... /ISSUED 1002 PM CDT FRI SEP 21 2012/
UPDATE...
A SPOTTER NEAR CHISHOLM HAD REPORTED THE RAIN HAD SWITCHED OVER TO
SNOW...WITH A QUARTER INCH OF ACCUMULATION. RAP AND NAM BOTH SHOW
LOWEST FREEZING LEVELS ACROSS THE NORTH...AND SINK IT SOUTH AND
WEST OVER THE NEXT FEW HOURS...THEN ACTUALLY INCREASE FREEZING
LEVELS LATE TONIGHT. KHIB/KEVM OBSERVATIONS HAVE ALSO SWITCHED
TO SNOW...AT LEAST BRIEFLY. WE WILL UPDATE AND EXPAND COVERAGE OF
SNOW. WE STILL THINK ACCUMULATIONS WILL BE QUITE LIMITED AS THE
GROUND SHOULD MELT MUCH OF THE SNOW...PERHAPS WITH SOME MINOR
ACCUMULATION ON GRASSY SURFACES/DECKS.
PREV DISCUSSION... /ISSUED 829 PM CDT FRI SEP 21 2012/
UPDATE...
SURFACE TEMPS DROPPING QUICKLY THIS EVENING...WITH SEVERAL OBS
FROM 36-39 DEGREES FROM PINE RIVER TO CRANE LAKE AND INTERNATIONAL
FALLS. A SPOTTER NEAR BLACKDUCK REPORTED SOME SLEET...AND AFTER
LOOKING AT LOW LEVEL TEMPERATURES WE FEEL THAT IS A THREAT OVER
PORTIONS OF OUR NORTHERN CWA THIS EVENING. THE ONE DRAW BACK FOR
US WILL BE PRECIP RATES...AS THEY HAVE COME DOWN AS THE MORE
CONVECTIVE SHOWERS WERE OCCURRING FURTHER EAST. WE EXPANDED THE
CHANCE FOR SNOW SHOWERS LATER TONIGHT FURTHER SOUTH INTO THE
BRAINERD LAKES REGION...GIVEN COLDER 925MB FORECAST DOWN THERE. WE
DON`T EXPECT ANY SNOW ACCUMULATION GIVEN SURFACE TEMPS EXPECTED TO
BE AT OR ABOVE FREEZING FOR MOST AREAS...AND WARM GROUND
TEMPERATURES.
PREV DISCUSSION... /ISSUED 308 PM CDT FRI SEP 21 2012/
SHORT TERM...TONIGHT THROUGH SUNDAY MORNING...CURRENT SURFACE ANALYSIS
INDICATE RAIN SHOWERS ASSOCIATED WITH A SHORTWAVE MOVING SE
THROUGH SOUTHERN CANADA ACROSS NORTHERN MINNESOTA AND A PORTION
OF NORTHWEST WISCONSIN. SOME OF THESE CELLS HAVE HAD REPORTS OF
PEA TO DINE SIZE HAIL/GRAUPEL. THIS ACTIVITY WILL CONTINUE SPREAD
SOUTHEAST THIS AFTERNOON AND EVENING AS THE SHORTWAVE MOVES INTO
MINNESOTA. THE SCATTERED SHOWERS WILL CONTINUE TONIGHT ACROSS THE
FORECAST AREA. ONE QUESTIONS FOR TONIGHT WILL BE THE POSSIBILITY
OF SNOW BEING MIXED IN WITH THE RAIN. MODELS INDICATE THICKNESSES
WILL BE COLD ENOUGH FOR SNOW WITH THE BEST SHOW NORTH OF HIGHWAY 2
IN MN. THE PRECIP WILL END ACROSS MN EARLY SATURDAY MORNING BUT
MAY LINGER IN EASTERN PORTIONS OF NW WI WHERE SOME LAKE EFFECT
SHOWERS MAY BE POSSIBLE AND THE INFLUENCE OF THE SHORTWAVE ACROSS
THE AREA.
THE NEXT CONCERN FOR THE SHORT TERM WILL BE HARD FREEZE CHANCE
SATURDAY NIGHT. SKIES WILL CLEAR OUT SATURDAY AFTERNOON AND IT WILL
BE MAINLY CLEAR SATURDAY NIGHT. MODELS INDICATE TEMPS TO BE IN THE
MIDDLE TO UPPER 20S WITH DRIER AIR ACROSS MOST AREAS SUNDAY
MORNING. WILL ISSUE A FREEZE WATCH FOR AREA SOUTH OF HIGHWAY 2 IN
MN AND ALL OF NW WI FOR SUNDAY MORNING. THESE TEMPS WILL END THE
GROWING SEASON ACROSS THE FORECAST AREA.
LONG TERM...SUNDAY THROUGH FRIDAY...THIS TIME PERIOD WILL BE A REALLY
QUIET TIME ACROSS THE NORTHLAND. THE UPPER LEVEL PATTERN WILL
GRADUALLY TRANSITION FROM A MEAN TROUGH ACROSS THE GREAT LAKES TO A
MEAN RIDGE BY WEDNESDAY. IT LOOKS LIKE THERE WILL BE PLENTY OF
SUNSHINE AND TEMPERATURES RANGING FROM THE 50S TO LOWER 60S
THROUGHOUT THE PERIOD. A FEW BACK DOOR COLD FRONTS WILL TRY TO MAKE
SOME PROGRESSION INTO THE AREA DURING THE EARLY PART OF THE WORK
WEEK...BUT UPPER LEVEL RIDGING WILL EVENTUALLY WIN OUT TOWARD THE
MIDDLE OF THE WEEK. THE PATTERN WILL THEN CHANGE ONCE AGAIN TOWARD
THE VERY END OF THE WORK WEEK...AS A MEAN UPPER LEVEL TROUGH PATTERN
ONCE AGAIN DEVELOPS. OVERALL IT LOOKS DRY FOR ALL OR NEARLY ALL OF
THE EXTENDED TIME PERIOD.
&&
.POINT TEMPS/POPS...
DLH 50 29 54 39 / 30 0 0 0
INL 48 23 54 38 / 10 0 0 0
BRD 51 28 57 36 / 20 0 0 0
HYR 52 27 54 36 / 40 10 0 0
ASX 53 31 52 39 / 60 40 10 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...FREEZE WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
MNZ033>038.
WI...FREEZE WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
WIZ001>004-006>009.
LS...SMALL CRAFT ADVISORY UNTIL NOON CDT SUNDAY FOR LSZ121-146>148.
&&
$$
SHORT TERM...GSF
LONG TERM....GROCHOCINSKI
AVIATION...GROCHOCINSKI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CDT FRI SEP 21 2012
.SHORT TERM...TONIGHT INTO SATURDAY MORNING
922 PM CDT FRI SEP 21 2012
THE MAIN SHORT TERM UPDATES TO THE FORECAST WERE WITH BEEFING UP
THE WIND SPEEDS AND ADJUSTING THE PRECIPITATION CHANCES FOR
OVERNIGHT AS THE COLD FRONT QUICKLY MOVES THROUGH AND THE POTENT
MID LEVEL TROUGH SWINGS DOWN.
WINDS ACROSS MUCH OF NORTHERN MINNESOTA HAVE JUMPED UP TO HAVING
SUSTAINED WINDS OF 20-30MPH WITH GUSTS UP TO 40MPH AT
TIMES...PARTICULARLY UNDER THE STRONGEST COLD PUSH WHICH IS
DROPPING STRAIGHT SOUTH ACROSS MINNESOTA. THIS TIGHT PRESSURE
GRADIENT MOVES INTO THE REGION OVERNIGHT BEHIND THE FRONT...SO
HAVE NO REASON TO THINK THAT THESE HIGH GUSTS WILL NOT CARRY INTO
THE REGION POST-FROPA.
PRECIPITATION-WISE...THERE WILL BE TWO MAIN WAVES THAT WILL
PRODUCE SHOWERS FOR THE REGION WITH ONE COMING THROUGH WITH THE
COLD FRONT AND THE SECOND...MORE WIDESPREAD BATCH COMING WITH THE
CORE OF THE MID LEVEL TROUGH. THERE STILL DOES APPEAR TO BE A
TINY WINDOW OF OPPORTUNITY FOR THE LOW LEVELS TO BE COOL ENOUGH
FOR SOME SNOW SHOWERS TO OCCUR ACROSS CENTRAL WISCONSIN WHERE THE
CORE OF THE MID LEVEL LOW DROPS THROUGH. 21.23Z RAP FORECAST
SOUNDINGS FROM ACROSS WESTERN WISCONSIN MIMIC THAT OF THE 22.00Z
INTERNATIONAL FALLS SOUNDING ALONG WITH OTHER LAPS SOUNDINGS FROM
PORTIONS OF SOUTHWEST ONTARIO THAT HAVE REPORTED SNOW SHOWERS THIS
EVENING. THE MAIN DETRIMENT TO THE SNOW OCCURRING DOWN HERE IS
PROBABLY WITH THE PRECIPITATION RATES NOT BEING AS HIGH COMPARED
TO WHAT IS CURRENTLY OCCURRING IN SOUTHWEST ONTARIO. THAT MAY
MEAN THAT THE ICE CRYSTAL/SNOWFLAKE HAS A LONGER RESIDENCE TIME IN
THE SHALLOW LAYER OF 0 TO +2C AIR FROM THE SFC UP TO 2KFT THAT
WILL ALLOW FOR IT TO MELT. SO...IT STILL LOOKS LIKE A FEW
SNOWFLAKES COULD FLY ACROSS CLARK/TAYLOR/JACKSON COUNTIES
OVERNIGHT...PARTICULARLY IN HIGHER ELEVATIONS...BUT NOTHING STRONG
ENOUGH THAT ANY ACCUMULATIONS SHOULD OCCUR.
.LONG TERM...MONDAY NIGHT THROUGH FRIDAY
256 PM CDT FRI SEP 21 2012
LATEST GFS AND ECMWF IN GENERALLY GOOD AGREEMENT THROUGH WEDNESDAY.
BOTH MODELS SHOW A WEAK COLD FRONT DROPPING SOUTH ACROSS THE AREA
MONDAY/MONDAY NIGHT WITH MORE OR LESS JUST A WIND SHIFT EXPECTED.
PLAN ON HIGHS MONDAY AND TUESDAY IN THE MID 60S TO A FEW LOWER 70S.
A SLIGHTLY COOLER AIR MASS SEEPS INTO THE AREA ON WEDNESDAY WITH
HIGHS IN THE 60S. FOR THURSDAY INTO FRIDAY...THE 21.12Z GFS SHOWS A
WEAK MID-LEVEL TROUGH ROTATING ACROSS THE CENTRAL CONUS WITH ANY PCPN
STAYING SOUTH OF OUR AREA. THE ECMWF SHOWS MORE VIGOROUS TROUGHING
INTO THE AREA AND THUS PRODUCES SOME PCPN FOR THE AREA THURSDAY
NIGHT INTO FRIDAY. WILL STICK WITH A DRY FORECAST FOR NOW AND GO
WITH MODEL CONSENSUS TEMPERATURES...WHICH YIELDS HIGHS THURSDAY AND FRIDAY
IN THE 60S.
&&
.AVIATION...THROUGH 06Z SUNDAY
1138 PM CDT FRI SEP 21 2012
A STRONG COLD FRONT IS POISED TO MOVE THROUGH THE REGIONAL TAF
SITES RIGHT AROUND 5-6Z WITH WINDS QUICKLY STRENGTHENING OUT OF
THE NORTHWEST AFTER IT PASSES. A BRIEF PERIOD OF RAIN SHOWERS WILL
MOVE THROUGH WITH THE FRONT BEFORE MORE WIDESPREAD SHOWERS SET UP
ACROSS WESTERN WISCONSIN EARLY SATURDAY MORNING. LSE HAS A BETTER
SHOT OF SEEING A LONGER PERIOD OF LIGHT RAIN THROUGH THE
MORNING.,.THOUGH THE LATEST TRENDS HAVE BEEN TO TAKE THIS BAND
FURTHER EAST. AFTER A BRIEF LOWERING OF VFR CEILINGS AS THE FRONT
PASSES THROUGH...THERE WILL BE A BREAK BEFORE THE CORE OF THE LOW
DROPS DOWN AND BRINGS SOME MVFR TO IFR CEILINGS ALONG WITH IT. MVFR
TO IFR CONDITIONS ALREADY ARE IN PLACE FROM NORTHWEST WISCONSIN
INTO NORTHEAST MINNESOTA ALONG THE EASTERN SIDE OF THE LOW. LSE
WILL HAVE A BETTER CHANCE OF CATCHING SOME OF 900FT IFR CEILINGS
THIS MORNING BUT THE CORE OF THESE LOWER CIGS WILL BE TO THE EAST
AND NOT END UP THERE. THIS PRECIPITATION SHOULD CLEAR LSE AROUND
DAYBREAK IN THE 11-13Z TIME FRAME BUT THE 1-2KFT CEILINGS WILL
LIKELY HOLD ON THROUGH MUCH OF THE MORNING BEFORE CLEARING IN THE
AFTERNOON/EVENING.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
256 PM CDT FRI SEP 21 2012
WI...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
WIZ017-029-032>034-041>044-053>055-061.
MN...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
MNZ079-086>088-094>096.
IA...FREEZE WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY MORNING FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...HALBACH
LONG TERM....DAS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
500 AM MST SAT SEP 22 2012
.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS.
&&
.SYNOPSIS...
HIGH PRESSURE IN THE UPPER ATMOSPHERE WILL RESULT IN WELL ABOVE
NORMAL TEMPERATURES THROUGH THIS WEEKEND. A COOLING TREND IS
EXPECTED STARTING MONDAY AS AN AREA OF LOW PRESSURE MOVES THROUGH
THE SOUTHERN ROCKIES. THERE IS ALSO A SLIGHT CHANCE OF SHOWERS
MONDAY...THOUGH MUCH OF THE AREA WILL NOT SEE RAINFALL. BELOW
AVERAGE TEMPERATURES ARE EXPECTED FROM TUESDAY THROUGH AT LEAST THE
WEEKEND.
&&
.DISCUSSION...
LATEST RAP ANALYSIS SHOWS THE ANTICYCLONE REORGANIZING ACROSS NM
EARLY THIS MORNING. THIS HAS RESULTED IN A VEERING FLOW AND AN
INCREASE IN SOUTHERLY WINDS IN THE MID-LEVELS ACROSS SOUTH-CENTRAL
AZ. MEANWHILE...LATEST TUCSON 00Z SOUNDING CONTINUES TO PICK UP ON
THE MOISTURE SITTING JUST BELOW A PERSISTENT SUBSIDENCE INVERSION
AROUND 500 MB. GIVEN THE STEERING FLOW...ALTOSTRATUS WILL LIKELY
MAKE ANOTHER APPEARANCE THIS MORNING. INCREASE IN MID CLOUDS AND
CIRRUS IN SOUTHERN CA AHEAD OF THE PACIFIC TROUGH WILL INHIBIT SOLAR
INSOLATION EVER SO SLIGHTLY AND MAX TEMPS FOR THIS AFTERNOON WERE
LOWERED ABOUT A DEGREE. NEVERTHELESS...MAX TEMPS WILL REMAIN WELL
ABOVE AVERAGE AND AROUND 105 DEGREES IN PHOENIX. LITTLE CHANGE IN
TEMPERATURES IS EXPECTED SUNDAY AS THE VORT MAX CURRENTLY OFF THE WA
COAST DROPS TO THE SOUTHEAST AND INTO THE GREAT BASIN.
MODELS REMAIN SOMEWHAT OUT OF PHASE WITH REGARD TO THE EVOLUTION OF
THE GREAT BASIN LOW PRESSURE SYSTEM EARLY NEXT WEEK...THOUGH
STRONGER WEIGHT WAS ASSIGNED TO THE NAM AND ECMWF WHICH HAVE
EXHIBITED A TREND TOWARDS LOWER HEIGHTS FURTHER SOUTH.
CONSEQUENTLY...POPS WERE INCREASED SLIGHTLY AND TOP OUT AT AROUND 20
PERCENT ACROSS EASTERN GILA COUNTY MONDAY AFTERNOON. LOWER LEVELS
WILL GENERALLY REMAIN TOO DRY FOR MEASURABLE PRECIPITATION IN THE
LOWER DESERTS. IN TERMS OF SENSIBLE WEATHER...MAIN IMPACT FROM THIS
SYSTEM WILL BE A DROP IN TEMPERATURES MONDAY INITIALLY...AND THEN
BEHIND THE TROUGH AXIS TUESDAY AND WEDNESDAY.
DETERMINISTIC MODELS SUGGEST SEVERAL MID-LATITUDE AND SUB-TROPICAL
VORTICES WILL CONSOLIDATE INTO A CUTOFF LOW IN THE VICINITY OF THE
BAJA PENINSULA LATE NEXT WEEK. TAKING THE GUIDANCE AT FACE VALUE
WOULD MEAN AN INCREASE IN MOISTURE FRIDAY-SATURDAY ACROSS MEXICO.
HOWEVER...ECWMF/GFS/CMC ENSEMBLES ARE ALL SHOWING A CONSIDERABLE
SPREAD AND THIS IS TO BE EXPECTED...GIVEN THAT CUTOFFS IN THIS
REGION ARE NOTORIOUSLY DIFFICULT TO FORECAST...PARTICULARLY IN THE
EXTENDED RANGE. MOST LIKELY SCENARIO IS THAT THE DRIER CLIMATOLOGY
WILL WIN OUT AND POPS WERE LOWERED BELOW 10 PERCENT.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
MOSTLY SUNNY SKIES WITH SCT-BKN MID-HIGH LEVEL CLOUDS OVER THE
REGION DURING THE PERIOD. EXPECT LIGHT WINDS LESS THAN 10KT AT ALL
TAF SITES THROUGH AT LEAST 09Z SUNDAY MORNING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
WARMER THAN AVERAGE TEMPERATURES EARLY IN THE WEEK WILL ABRUPTLY
COOL TOWARDS SEASONAL NORMALS AS A WEAK LOW PRESSURE SYSTEM MOVES
THROUGH THE GREAT BASIN MONDAY AND TUESDAY. WITH THE PASSAGE OF THIS
LOW PRESSURE SYSTEM...SOUTHWEST WINDS WILL INCREASE AND BECOME GUSTY
UP TO 25 MPH ACROSS SOUTHEAST CALIFORNIA AS WELL AS THE HIGHER
ELEVATIONS OF SOUTH-CENTRAL ARIZONA MONDAY AFTERNOON. WIND SPEEDS
WILL TAPER OFF AND FOLLOW MORE TYPICAL DIRECTIONAL TRENDS TUESDAY
THROUGH FRIDAY. DAYTIME HUMIDITY LEVELS WILL GRADUALLY TREND UP FROM
THE TEENS TO BACK ABOVE 20 PERCENT ACROSS THE LOWER DESERTS BY THE
END OF THE WEEK...ACCOMPANIED BY GOOD RECOVERY EACH NIGHT.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
AVIATION...MEYERS
FIRE WEATHER...MO
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
400 AM MST SAT SEP 22 2012
.SYNOPSIS...
HIGH PRESSURE IN THE UPPER ATMOSPHERE WILL RESULT IN WELL ABOVE
NORMAL TEMPERATURES THROUGH THIS WEEKEND. A COOLING TREND IS
EXPECTED STARTING MONDAY AS AN AREA OF LOW PRESSURE MOVES THROUGH
THE SOUTHERN ROCKIES. THERE IS ALSO A SLIGHT CHANCE OF SHOWERS
MONDAY...THOUGH MUCH OF THE AREA WILL NOT SEE RAINFALL. BELOW
AVERAGE TEMPERATURES ARE EXPECTED FROM TUESDAY THROUGH AT LEAST THE
WEEKEND.
&&
.DISCUSSION...
LATEST RAP ANALYSIS SHOWS THE ANTICYCLONE REORGANIZING ACROSS NM
EARLY THIS MORNING. THIS HAS RESULTED IN A VEERING FLOW AND AN
INCREASE IN SOUTHERLY WINDS IN THE MID-LEVELS ACROSS SOUTH-CENTRAL
AZ. MEANWHILE...LATEST TUCSON 00Z SOUNDING CONTINUES TO PICK UP ON
THE MOISTURE SITTING JUST BELOW A PERSISTENT SUBSIDENCE INVERSION
AROUND 500 MB. GIVEN THE STEERING FLOW...ALTOSTRATUS WILL LIKELY
MAKE ANOTHER APPEARANCE THIS MORNING. INCREASE IN MID CLOUDS AND
CIRRUS IN SOUTHERN CA AHEAD OF THE PACIFIC TROUGH WILL INHIBIT SOLAR
INSOLATION EVER SO SLIGHTLY AND MAX TEMPS FOR THIS AFTERNOON WERE
LOWERED ABOUT A DEGREE. NEVERTHELESS...MAX TEMPS WILL REMAIN WELL
ABOVE AVERAGE AND AROUND 105 DEGREES IN PHOENIX. LITTLE CHANGE IN
TEMPERATURES IS EXPECTED SUNDAY AS THE VORT MAX CURRENTLY OFF THE WA
COAST DROPS TO THE SOUTHEAST AND INTO THE GREAT BASIN.
MODELS REMAIN SOMEWHAT OUT OF PHASE WITH REGARD TO THE EVOLUTION OF
THE GREAT BASIN LOW PRESSURE SYSTEM EARLY NEXT WEEK...THOUGH
STRONGER WEIGHT WAS ASSIGNED TO THE NAM AND ECMWF WHICH HAVE
EXHIBITED A TREND TOWARDS LOWER HEIGHTS FURTHER SOUTH.
CONSEQUENTLY...POPS WERE INCREASED SLIGHTLY AND TOP OUT AT AROUND 20
PERCENT ACROSS EASTERN GILA COUNTY MONDAY AFTERNOON. LOWER LEVELS
WILL GENERALLY REMAIN TOO DRY FOR MEASURABLE PRECIPITATION IN THE
LOWER DESERTS. IN TERMS OF SENSIBLE WEATHER...MAIN IMPACT FROM THIS
SYSTEM WILL BE A DROP IN TEMPERATURES MONDAY INITIALLY...AND THEN
BEHIND THE TROUGH AXIS TUESDAY AND WEDNESDAY.
DETERMINISTIC MODELS SUGGEST SEVERAL MID-LATITUDE AND SUB-TROPICAL
VORTICES WILL CONSOLIDATE INTO A CUTOFF LOW IN THE VICINITY OF THE
BAJA PENINSULA LATE NEXT WEEK. TAKING THE GUIDANCE AT FACE VALUE
WOULD MEAN AN INCREASE IN MOISTURE FRIDAY-SATURDAY ACROSS MEXICO.
HOWEVER...ECWMF/GFS/CMC ENSEMBLES ARE ALL SHOWING A CONSIDERABLE
SPREAD AND THIS IS TO BE EXPECTED...GIVEN THAT CUTOFFS IN THIS
REGION ARE NOTORIOUSLY DIFFICULT TO FORECAST...PARTICULARLY IN THE
EXTENDED RANGE. MOST LIKELY SCENARIO IS THAT THE DRIER CLIMATOLOGY
WILL WIN OUT AND POPS WERE LOWERED BELOW 10 PERCENT.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
VERY LITTLE CHANGE IN THE WEATHER PATTERN EXPECTED OVER THE NEXT 24
HOURS. WILL CONTINUE TO SEE STRONG HIGH PRESSURE ALOFT WITH SOME HI
BASED CU...BASES AOA 12K FEET...DEVELOPING DURING THE LATE MORNING
OR EARLY AFTERNOON TOMORROW. OTHERWISE SKIES TO BE MOSTLY CLEAR NEXT
24 HOURS WITH WINDS ON THE LIGHT SIDE AND FOLLOWING NORMAL DIURNAL
PATTERNS. NO AVIATION CONCERNS THROUGH SATURDAY EVENING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
WARMER THAN AVERAGE TEMPERATURES EARLY IN THE WEEK WILL ABRUPTLY
COOL TOWARDS THE SEASONAL NORMALS AS A WEAK LOW PRESSURE SYSTEM
MOVES THROUGH THE GREAT BASIN MONDAY AND TUESDAY. WITH THE PASSAGE
OF THIS LOW PRESSURE SYSTEM...SOUTHWEST WINDS WILL INCREASE AND
BECOME GUSTY UP TO 25 MPH ACROSS SOUTHEAST CALIFORNIA AS WELL AS
OVER THE HIGHER ELEVATIONS OF SOUTH CENTRAL ARIZONA MONDAY
AFTERNOON. WIND SPEEDS WILL TAPER OFF AND FOLLOW THE MORE TYPICAL
DIRECTIONAL TRENDS TUESDAY THROUGH FRIDAY. DAYTIME HUMIDITY LEVELS
WILL GRADUALLY TREND UP FROM THE TEENS TO BACK ABOVE 20 PERCENT
ACROSS THE LOWER DESERTS BY THE END OF THE WEEK...ACCOMPANIED BY
GOOD RECOVERY EACH NIGHT.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH
AVIATION...CB
FIRE WEATHER...MO
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1015 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A SHORT PERIOD OF HIGH PRESSURE WILL BRING A BRIEF WARM UP
TODAY AFTER SKIES CLEAR LATER THIS MORNING. A COLD FRONT WILL THEN
BRING SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS LATE
TODAY INTO TONIGHT. HIGH PRESSURE AND DRIER CONDITIONS BUILD INTO
NEW ENGLAND SUNDAY WITH COOLER WEATHER FOR THE FIRST HALF OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1015 AM UPDATE...UPDATED SKY COVER GRIDS TO ONCE AGAIN SLOW THE
CLEARING. ALSO ADJUSTED TEMPERATURES AND DEWPOINTS TO LOWER TEMPS
SLIGHTLY AND BRING THEM MORE IN LINE WITH CURRENT TRENDS. STILL
ANTICIPATING THAT THE STRATUS WILL DISSIPATE LATER THIS MORNING WITH
WESTERLY WINDS AND EXTREMELY DRY AIR JUST ABOVE THE STRATUS DECK.
PREVIOUS DISCUSSION...
BANK OF STRATUS STILL BUILDING OVER SRN NEW ENGLAND THIS HOUR AS
WEAK SFC WARM FRONT SHIFTS INTO NRN NEW ENGLAND. NAM/RGEM HANDLING
THIS STRATUS WELL SO ADJUSTED SKIES TOWARD ITS SOLN. GIVEN THE
INCREASING DWPTS AND SUBSIDENCE BENEATH THE WEAK RIDGE...IT MAY
TAKE SOME TIME FOR THIS STRATUS TO COMPLETELY BREAK...BUT BL
MIXING SHOULD TAKE OVER BY ABOUT MID MORNING GIVEN THE EXPECTED
INSOLATION IN THE DRY SUBSIDENCE. THE STRATUS WILL LIKELY DELAY
DIURNAL TEMP INCREASE HOWEVER...SO ADJUSTED TOWARD THE 5 DAY BIAS
CORRECTED GRIDS ALONG WITH THE MOST RECENT HRRR WHICH SUPPORTED
THIS THINKING.
STRONG KICKER WAVE WILL BE FORCING PERSISTENT GREAT LAKES CUTOFF
TO BEGIN MIGRATION N WITH TIME...ALONG WITH A SFC LOW PRES SYSTEM.
THIS WILL ALLOW A COLD FRONT TO BEGIN MOVING TOWARD THE REGION BY
LATE IN THE DAY. THE COMBINATION OF COOLING TEMPERATURES ALOFT
WITH THIS WAVE...SFC DIABATIC WARMING AFTER THE STRATUS CLEARS...
AND SFC DWPT RISES IN MOISTENING SLY FLOW...WILL LEAD TO MODEST
DESTABILIZATION OF THE COLUMN AS THE FRONT APPROACHES. SB CAPE
VALUES ARE FORECAST TO ONLY REACH 500-1000 J/KG BY LATE DAY. GIVEN
THE LATE ARRIVAL OF THE FRONT /ON THE DOORSTEP OF WRN MA BY
00Z/...WEAKENING DYNAMICS AS THE BEST JET ENERGY LIFTS N WITH THE
WAVE...AND A VERY DRY COLUMN /PWAT VALUES STRUGGLE TO BREAK 1.25
INCHES/ IT WILL LIKELY TAKE MOST OF THE DAY FOR ANY POTENTIAL
PRECIP/TSTMS TO GET GOING. THERE IS SOME MODERATE SHEAR WITH AN
H85 JET BETWEEN 30 AND 40 KT TO WORK WITH...BUT WITH MODEST
INSTABILITY AND DRY AIR THE BEST CHANCE FOR STORMS WILL LIKELY BE
UPSTREAM. WITH A HIGHER SHEAR...LOWER INSTABILITY SCENARIO...WILL
LIKELY NEED TO MONITOR FOR A THIN LINE OF LOW TOPPED CONVECTION
CLOSELY ASSOCIATED WITH THE FRONT ITSELF...WHICH WOULD ARRIVE BY
LATE EVENING. ANY BOWING SECTIONS MAY BE ABLE TO TAP SOME OF THE
JET ENERGY. GIVEN ALL OF THESE FACTORS...HAVE LIMITED POPS MUCH OF
THE DAY...WITH LIKELY POPS ONLY REACH THE EAST SLOPES OF THE
BERKSHIRES BY LATE 00Z. SPC CONTINUES TO KEEP SLIGHT RISK JUST TO
THE W OF THE CWA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
SFC COLD FRONT WILL BE MOVING RAPIDLY THROUGH THE AREA AS STRONG
KICKER TROF FORCES LONGWAVE AND ASSOCIATED LOW PRES INTO CANADA.
GIVEN THIS...THE BEST DYNAMICS AND FGEN EXIT TO THE N WITH TIME.
SO EXPECT THE FRONT TO RAPIDLY WEAKEN AND STRETCH OUT WITH
TIME...ESPECIALLY AS IT INTERACTS WITH PERSISTENTLY DRY COLUMN
OVER ERN PORTIONS OF THE FA. HAVE POPS DIMINISHING RAPIDLY
ESPECIALLY AFTER MIDNIGHT LOCAL. WITH LOSS OF DIURNAL HEATING AND
DRIER MORE STABLE AIRMASS TO THE E...THE WEAKENING SOURCE OF
LIFT...TSTMS/SHOWERS WILL LIKELY BE GRADUALLY DIMINISHING WITH
TIME. ALTHOUGH WE HAVE SLIGHT CHANCE POPS FOR ERN COUNTIES...IT IS
POSSIBLE THAT SOME AREAS MAY SEE LITTLE TO NO PRECIP AT ALL.
WILL NEED TO CONTINUE TO MONITOR FOR A FINE LINE AS MENTIONED
ABOVE HOWEVER...ESPECIALLY IN THE EARLY OVERNIGHT HOURS...WHICH
MAY PROVIDE SOME GUSTY WINDS AND BRIEF HEAVY RAINFALL...BUT THIS
REMAINS A THREAT MOSTLY W OF THE WORCESTER HILLS.
SUN...
GIVEN THAT TIMING OF THE FRONT IS GENERALLY WELL AGREED UPON BY
MODELS...HAVE REASONABLY HIGH CONFIDENCE THAT IT SHOULD BE MOVING
E OF CAPE COD BY 12Z. WITH STRONG COOL ADVECTION AND NW FLOW
SHOULD SEE SOME RAPIDLY EARLY DAY CLEARING FROM W TO E AS THE DRY
COOL AIRMASS WORKS ITS WAY IN. MODELS MAY BE STRUGGLING SOMEWHAT
IN THIS EARLY FALL CAA REGIME AS RAW DATA SUGGESTS SKC CONDITIONS
AND LIGHT WINDS FOR MUCH OF THE DAY. SOUNDINGS SHOW 15 TO 20 KT
AVAILABLE FOR DAYTIME MIXING AND SOME TRAPPED MOISTURE AROUND
H9-H8. THEREFORE...HAVE INCREASED MID DAY CLOUDINESS AND WIND
GUSTS SOMEWHAT FROM GRIDDED MODEL DATA. OTHERWISE A MOSTLY DRY
DAY. H85 TEMPERATURES WILL BE COOLING WITH TIME BUT ONLY REACH
ABOUT +6C BY PEAK HEATING...THEREFORE TEMPERATURES IN THE UPPER
60S TO LOWER 70S WILL LIKELY REMAIN.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
BIG PICTURE...
NO MAJOR CHANGES NOTED WITH THE 22/00Z MODEL SUITE FROM THE 21/12Z
GUIDANCE. 22/00Z GUIDANCE IS STILL IN DECENT AGREEMENT WITH THE
OVERALL SYNOPTIC PATTERN NEXT WEEK...WITH SOME TIMING DIFFERENCES
STILL.
EARLY WEEK PATTERN SHOWS RIDGE WEST/TROUGH EAST WITH A CLOSED LOW
IN THE VICINITY JAMES BAY CANADA. THIS CONTINUES THROUGH MIDWEEK
AS THE WESTERN RIDGE SLOWLY DE-AMPLIFIES. ONE SHORTWAVE ROTATES
THROUGH THE EASTERN CYCLONIC FLOW AND CROSSES NEW ENGLAND MONDAY.
THIS TROUGH ITSELF BECOMES PROGRESSIVE MIDWEEK WITH THE TROUGH
AXIS CROSSING NEW ENGLAND AROUND THURSDAY.
THE MODEL SOLUTIONS AT 500 MB ARE CONSISTENT THROUGH MONDAY. THE
22/00Z GFS AND GGEM ARE FASTER TO EJECT THE CLOSED LOW EAST BY
WEDNESDAY. MEANWHILE THE 22/00Z ECMWF HOLDS IT OVER EASTERN CANADA
UNTIL THURSDAY. BOTH THE GFS AND ECMWF MOVE THE TROUGH AXIS OR A
SEMBLANCE OF ONE THROUGH OUR AREA ABOUT THURSDAY.
MONDAY...
THIS IS A TRICKY FORECAST PERIOD. EXPECTING A FAIRLY POTENT
SHORTWAVE TO MOVE ACROSS SOUTHERN NEW ENGLAND DURING THIS PERIOD.
THE MAIN QUESTION LEFT TO BE ANSWERED WILL BE THE AMOUNT OF
MOISTURE AVAILABLE TO BE PUT INTO CLOUDS AND SHOWERS. AS MENTIONED
BY PREVIOUS SHIFT...THIS PATTERN DOES FAVOR AT LEAST SOME DIURNAL
CLOUDS. THINKING WHILE THERE MAY BE ENOUGH MOISTURE FOR SOME
CLOUDS...THERE IS NOT ENOUGH TO WARRANT MORE THAN A VERY LOW
CHANCE FOR RAINFALL.
ANY CLOUDS AND SHOWERS SHOULD DISSIPATE QUICKLY AFTER SUNSET
MONDAY EVENING.
TUESDAY...
SURFACE HIGH PRESSURE BUILDS OVER THE REGION. SHOULD BE A FAIR
WEATHER DAY. WARM ADVECTION ALOFT WILL CAP THE MIXED LAYER/KEEP IT
LOWER. MIXED TEMPERATURES FROM ALOFT SHOULD BE EQUIVALENT OF 5-7C
AT 850 MB...SUPPORTING MAX SURFACE TEMPERATURES AROUND 70F.
WEDNESDAY-THURSDAY...
THE TROUGH AXIS APPROACHES WEDNESDAY AND MOVES THROUGH WEDNESDAY
NIGHT OR THURSDAY. SOUTHWEST SURFACE WINDS WILL BRING WARMER
TEMPERATURES AND HIGHER DEW POINTS /50S/. THIS UPPER TROUGH WILL BE
IN THE ST LAWRENCE VALLEY IN THE AFTERNOON...SO EXPECT MOST
RAINFALL TO REMAIN NORTH OF OUR AREA. COULD BE CHANCE POPS TOWARD
WEDNESDAY EVENING ACROSS OUR NORTHERN AREAS. SHOWERS THEN MOVE
ACROSS SOUTHERN NEW ENGLAND WEDNESDAY NIGHT AND THURSDAY...ENDING
WITH THE WIND SHIFT. CHANCE POPS DURING THIS PERIOD. TEMPERATURES
ARE A BLEND OF HPC AND GMOS.
FRIDAY...
HIGH PRESSURE BUILDS WITH FAIR DRY WEATHER. USED A BLEND OF HPC
AND GMOS GUIDANCE.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN TIMING.
AREAS OF STRATUS AND FOG WILL GRADUALLY DISSIPATE THIS MORNING.
IT WILL LIKELY TAKE UNTIL 15Z OR SO BEFORE MOST STRATUS LIFTS TO
VFR ALONG THE EAST COAST...ESPECIALLY ACROSS THE CAPE AND
ISLANDS. PATCHY DRIZZLE AS WELL MAY PRODUCE A FEW HUNDREDTHS OF
PRECIPITATION...MARGINALLY WETTING RUNWAYS.
VFR THEN CONTINUES THROUGH THE REST OF TODAY UNTIL A WEAKENING
FRONT MOVES THROUGH TONIGHT. THERE IS THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WITH BRIEF MVFR CONDITIONS PARTICULARLY W OF ORH IN
THE EVENING...BUT GIVEN THE FRONT WILL BE WEAKENING WITH TIME
CONDITIONS SHOULD IMPROVE TO VFR DESPITE THE FROPA.
KBOS TAF...
HIGH CONFIDENCE TAF TRENDS...BUT LOWER CONFIDENCE IN TIMING.
IFR CONDITIONS GRADUALLY LIFT AFTER SUNRISE WITH VFR LIKELY
LINGERING INTO THE OVERNIGHT HOURS. A FAST MOVING FRONT WILL BRING
THE LOW PROB OF SHOWERS TONIGHT...BUT CONDITIONS REMAIN MOSTLY
VFR.
KBDL TAF...MODERATE CONFIDENCE IN TAF.
IFR TO START WITH IMPROVEMENT TO VFR DURING THE MID MORNING.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MODERATE CONFIDENCE. VFR EXPECTED.
&&
.MARINE...
MODERATE CONFIDENCE.
A BUILDING EASTERLY SWELL WILL BEGIN TO EFFECT E WATERS
FIRST...LIKELY RISING TO ABOUT 5-6 FT OVER THE OUTER WATERS BY MID
MORNING. IT WILL TAKE SOME TIME FOR THE S WATERS TO REACH 5
FT...BUT IT WILL LIKELY BUILD TO THIS LEVEL BY LATE THIS EVENING
AS WELL. THEREFORE...A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS HAS
BEEN ISSUED FOR THE OUTER WATERS AND NANTUCKET SOUND FR THIS
EASTERLY SWELL.
OTHERWISE...WINDS WILL GENERALLY REMAIN BELOW 25 KT THROUGH THE
PERIOD...HOWEVER A COLD FRONT WILL CROSS THE WATERS TONIGHT WITH
THE CHANCE FOR SOME BRIEF 20-30 KT GUSTS IN SHOWERS AND ISOLATED
THUNDERSTORMS...THE BEST CHANCE WILL BE SOUTHERN WATERS.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE.
MONDAY AND TUESDAY...MODERATE CONFIDENCE. DIMINISHING WINDS AND
SEAS AS HIGH PRESSURE BUILDS. NO HEADLINES ARE ANTICIPATED.
WEDNESDAY...MODERATE CONFIDENCE.
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT LEVELS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 8 PM THIS EVENING
TO 8 AM EDT SUNDAY FOR ANZ232-251-256.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT SUNDAY
FOR ANZ250-254-255.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...DOODY/RLG
SHORT TERM...DOODY
LONG TERM...BELK
AVIATION...BELK/DOODY
MARINE...BELK/DOODY
AREA FORECAST DISCUSSION
NWS TAUNTON MA
738 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A SHORT PERIOD OF HIGH PRESSURE WILL BRING A BRIEF WARM UP
TODAY AFTER SKIES CLEAR IN THE MORNING. A COLD FRONT WILL THEN
BRING SCATTERED SHOWERS AND POSSIBLY A FEW THUNDERSTORMS LATE
TODAY INTO TONIGHT. HIGH PRESSURE AND DRIER CONDITIONS BUILD INTO
NEW ENGLAND SUNDAY WITH COOLER WEATHER FOR THE FIRST HALF OF NEXT
WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
730 AM UPDATE...
SLOWED DOWN THE DEPARTURE OF CLOUD COVER THIS MORNING...AND
ADJUSTED TEMPERATURES BECAUSE OF THAT CHANGE. STRATUS SHOULD
DISSIPATE THIS MORNING WITH ABUNDANT DRY AIR ABOVE 900 MB. WILL
PROBABLY NEED TO WAIT FOR WINDS TO SHIFT WEST OR SOUTHWEST TO
REALLY BREAK IT UP ACROSS THE CAPE AND THE ISLANDS.
PREVIOUS DISCUSSION...
BANK OF STRATUS STILL BUILDING OVER SRN NEW ENGLAND THIS HOUR AS
WEAK SFC WARM FRONT SHIFTS INTO NRN NEW ENGLAND. NAM/RGEM HANDLING
THIS STRATUS WELL SO ADJUSTED SKIES TOWARD ITS SOLN. GIVEN THE
INCREASING DWPTS AND SUBSIDENCE BENEATH THE WEAK RIDGE...IT MAY
TAKE SOME TIME FOR THIS STRATUS TO COMPLETELY BREAK...BUT BL
MIXING SHOULD TAKE OVER BY ABOUT MID MORNING GIVEN THE EXPECTED
INSOLATION IN THE DRY SUBSIDENCE. THE STRATUS WILL LIKELY DELAY
DIURNAL TEMP INCREASE HOWEVER...SO ADJUSTED TOWARD THE 5 DAY BIAS
CORRECTED GRIDS ALONG WITH THE MOST RECENT HRRR WHICH SUPPORTED
THIS THINKING.
STRONG KICKER WAVE WILL BE FORCING PERSISTENT GREAT LAKES CUTOFF
TO BEGIN MIGRATION N WITH TIME...ALONG WITH A SFC LOW PRES SYSTEM.
THIS WILL ALLOW A COLD FRONT TO BEGIN MOVING TOWARD THE REGION BY
LATE IN THE DAY. THE COMBINATION OF COOLING TEMPERATURES ALOFT
WITH THIS WAVE...SFC DIABATIC WARMING AFTER THE STRATUS CLEARS...
AND SFC DWPT RISES IN MOISTENING SLY FLOW...WILL LEAD TO MODEST
DESTABILIZATION OF THE COLUMN AS THE FRONT APPROACHES. SB CAPE
VALUES ARE FORECAST TO ONLY REACH 500-1000 J/KG BY LATE DAY. GIVEN
THE LATE ARRIVAL OF THE FRONT /ON THE DOORSTEP OF WRN MA BY
00Z/...WEAKENING DYNAMICS AS THE BEST JET ENERGY LIFTS N WITH THE
WAVE...AND A VERY DRY COLUMN /PWAT VALUES STRUGGLE TO BREAK 1.25
INCHES/ IT WILL LIKELY TAKE MOST OF THE DAY FOR ANY POTENTIAL
PRECIP/TSTMS TO GET GOING. THERE IS SOME MODERATE SHEAR WITH AN
H85 JET BETWEEN 30 AND 40 KT TO WORK WITH...BUT WITH MODEST
INSTABILITY AND DRY AIR THE BEST CHANCE FOR STORMS WILL LIKELY BE
UPSTREAM. WITH A HIGHER SHEAR...LOWER INSTABILITY SCENARIO...WILL
LIKELY NEED TO MONITOR FOR A THIN LINE OF LOW TOPPED CONVECTION
CLOSELY ASSOCIATED WITH THE FRONT ITSELF...WHICH WOULD ARRIVE BY
LATE EVENING. ANY BOWING SECTIONS MAY BE ABLE TO TAP SOME OF THE
JET ENERGY. GIVEN ALL OF THESE FACTORS...HAVE LIMITED POPS MUCH OF
THE DAY...WITH LIKELY POPS ONLY REACH THE EAST SLOPES OF THE
BERKSHIRES BY LATE 00Z. SPC CONTINUES TO KEEP SLIGHT RISK JUST TO
THE W OF THE CWA.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
TONIGHT...
SFC COLD FRONT WILL BE MOVING RAPIDLY THROUGH THE AREA AS STRONG
KICKER TROF FORCES LONGWAVE AND ASSOCIATED LOW PRES INTO CANADA.
GIVEN THIS...THE BEST DYNAMICS AND FGEN EXIT TO THE N WITH TIME.
SO EXPECT THE FRONT TO RAPIDLY WEAKEN AND STRETCH OUT WITH
TIME...ESPECIALLY AS IT INTERACTS WITH PERSISTENTLY DRY COLUMN
OVER ERN PORTIONS OF THE FA. HAVE POPS DIMINISHING RAPIDLY
ESPECIALLY AFTER MIDNIGHT LOCAL. WITH LOSS OF DIURNAL HEATING AND
DRIER MORE STABLE AIRMASS TO THE E...THE WEAKENING SOURCE OF
LIFT...TSTMS/SHOWERS WILL LIKELY BE GRADUALLY DIMINISHING WITH
TIME. ALTHOUGH WE HAVE SLIGHT CHANCE POPS FOR ERN COUNTIES...IT IS
POSSIBLE THAT SOME AREAS MAY SEE LITTLE TO NO PRECIP AT ALL.
WILL NEED TO CONTINUE TO MONITOR FOR A FINE LINE AS MENTIONED
ABOVE HOWEVER...ESPECIALLY IN THE EARLY OVERNIGHT HOURS...WHICH
MAY PROVIDE SOME GUSTY WINDS AND BRIEF HEAVY RAINFALL...BUT THIS
REMAINS A THREAT MOSTLY W OF THE WORCESTER HILLS.
SUN...
GIVEN THAT TIMING OF THE FRONT IS GENERALLY WELL AGREED UPON BY
MODELS...HAVE REASONABLY HIGH CONFIDENCE THAT IT SHOULD BE MOVING
E OF CAPE COD BY 12Z. WITH STRONG COOL ADVECTION AND NW FLOW
SHOULD SEE SOME RAPIDLY EARLY DAY CLEARING FROM W TO E AS THE DRY
COOL AIRMASS WORKS ITS WAY IN. MODELS MAY BE STRUGGLING SOMEWHAT
IN THIS EARLY FALL CAA REGIME AS RAW DATA SUGGESTS SKC CONDITIONS
AND LIGHT WINDS FOR MUCH OF THE DAY. SOUNDINGS SHOW 15 TO 20 KT
AVAILABLE FOR DAYTIME MIXING AND SOME TRAPPED MOISTURE AROUND
H9-H8. THEREFORE...HAVE INCREASED MID DAY CLOUDINESS AND WIND
GUSTS SOMEWHAT FROM GRIDDED MODEL DATA. OTHERWISE A MOSTLY DRY
DAY. H85 TEMPERATURES WILL BE COOLING WITH TIME BUT ONLY REACH
ABOUT +6C BY PEAK HEATING...THEREFORE TEMPERATURES IN THE UPPER
60S TO LOWER 70S WILL LIKELY REMAIN.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
BIG PICTURE...
NO MAJOR CHANGES NOTED WITH THE 22/00Z MODEL SUITE FROM THE 21/12Z
GUIDANCE. 22/00Z GUIDANCE IS STILL IN DECENT AGREEMENT WITH THE
OVERALL SYNOPTIC PATTERN NEXT WEEK...WITH SOME TIMING DIFFERENCES
STILL.
EARLY WEEK PATTERN SHOWS RIDGE WEST/TROUGH EAST WITH A CLOSED LOW
IN THE VICINITY JAMES BAY CANADA. THIS CONTINUES THROUGH MIDWEEK
AS THE WESTERN RIDGE SLOWLY DE-AMPLIFIES. ONE SHORTWAVE ROTATES
THROUGH THE EASTERN CYCLONIC FLOW AND CROSSES NEW ENGLAND MONDAY.
THIS TROUGH ITSELF BECOMES PROGRESSIVE MIDWEEK WITH THE TROUGH
AXIS CROSSING NEW ENGLAND AROUND THURSDAY.
THE MODEL SOLUTIONS AT 500 MB ARE CONSISTENT THROUGH MONDAY. THE
22/00Z GFS AND GGEM ARE FASTER TO EJECT THE CLOSED LOW EAST BY
WEDNESDAY. MEANWHILE THE 22/00Z ECMWF HOLDS IT OVER EASTERN CANADA
UNTIL THURSDAY. BOTH THE GFS AND ECMWF MOVE THE TROUGH AXIS OR A
SEMBLANCE OF ONE THROUGH OUR AREA ABOUT THURSDAY.
MONDAY...
THIS IS A TRICKY FORECAST PERIOD. EXPECTING A FAIRLY POTENT
SHORTWAVE TO MOVE ACROSS SOUTHERN NEW ENGLAND DURING THIS PERIOD.
THE MAIN QUESTION LEFT TO BE ANSWERED WILL BE THE AMOUNT OF
MOISTURE AVAILABLE TO BE PUT INTO CLOUDS AND SHOWERS. AS MENTIONED
BY PREVIOUS SHIFT...THIS PATTERN DOES FAVOR AT LEAST SOME DIURNAL
CLOUDS. THINKING WHILE THERE MAY BE ENOUGH MOISTURE FOR SOME
CLOUDS...THERE IS NOT ENOUGH TO WARRANT MORE THAN A VERY LOW
CHANCE FOR RAINFALL.
ANY CLOUDS AND SHOWERS SHOULD DISSIPATE QUICKLY AFTER SUNSET
MONDAY EVENING.
TUESDAY...
SURFACE HIGH PRESSURE BUILDS OVER THE REGION. SHOULD BE A FAIR
WEATHER DAY. WARM ADVECTION ALOFT WILL CAP THE MIXED LAYER/KEEP IT
LOWER. MIXED TEMPERATURES FROM ALOFT SHOULD BE EQUIVALENT OF 5-7C
AT 850 MB...SUPPORTING MAX SURFACE TEMPERATURES AROUND 70F.
WEDNESDAY-THURSDAY...
THE TROUGH AXIS APPROACHES WEDNESDAY AND MOVES THROUGH WEDNESDAY
NIGHT OR THURSDAY. SOUTHWEST SURFACE WINDS WILL BRING WARMER
TEMPERATURES AND HIGHER DEW POINTS /50S/. THIS UPPER TROUGH WILL BE
IN THE ST LAWRENCE VALLEY IN THE AFTERNOON...SO EXPECT MOST
RAINFALL TO REMAIN NORTH OF OUR AREA. COULD BE CHANCE POPS TOWARD
WEDNESDAY EVENING ACROSS OUR NORTHERN AREAS. SHOWERS THEN MOVE
ACROSS SOUTHERN NEW ENGLAND WEDNESDAY NIGHT AND THURSDAY...ENDING
WITH THE WIND SHIFT. CHANCE POPS DURING THIS PERIOD. TEMPERATURES
ARE A BLEND OF HPC AND GMOS.
FRIDAY...
HIGH PRESSURE BUILDS WITH FAIR DRY WEATHER. USED A BLEND OF HPC
AND GMOS GUIDANCE.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...HIGH CONFIDENCE IN TRENDS BUT LOWER CONFIDENCE IN TIMING.
AREAS OF STRATUS AND FOG WILL GRADUALLY DISSIPATE THIS MORNING.
IT WILL LIKELY TAKE UNTIL 15Z OR SO BEFORE MOST STRATUS LIFTS TO
VFR ALONG THE EAST COAST...ESPECIALLY ACROSS THE CAPE AND
ISLANDS. PATCHY DRIZZLE AS WELL MAY PRODUCE A FEW HUNDREDTHS OF
PRECIPITATION...MARGINALLY WETTING RUNWAYS.
VFR THEN CONTINUES THROUGH THE REST OF TODAY UNTIL A WEAKENING
FRONT MOVES THROUGH TONIGHT. THERE IS THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WITH BRIEF MVFR CONDITIONS PARTICULARLY W OF ORH IN
THE EVENING...BUT GIVEN THE FRONT WILL BE WEAKENING WITH TIME
CONDITIONS SHOULD IMPROVE TO VFR DESPITE THE FROPA.
KBOS TAF...
HIGH CONFIDENCE TAF TRENDS...BUT LOWER CONFIDENCE IN TIMING.
IFR CONDITIONS GRADUALLY LIFT AFTER SUNRISE WITH VFR LIKELY
LINGERING INTO THE OVERNIGHT HOURS. A FAST MOVING FRONT WILL BRING
THE LOW PROB OF SHOWERS TONIGHT...BUT CONDITIONS REMAIN MOSTLY
VFR.
KBDL TAF...MODERATE CONFIDENCE IN TAF.
IFR TO START WITH IMPROVEMENT TO VFR DURING THE MID MORNING.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...
MODERATE CONFIDENCE. VFR EXPECTED.
&&
.MARINE...
MODERATE CONFIDENCE.
A BUILDING EASTERLY SWELL WILL BEGIN TO EFFECT E WATERS
FIRST...LIKELY RISING TO ABOUT 5-6 FT OVER THE OUTER WATERS BY MID
MORNING. IT WILL TAKE SOME TIME FOR THE S WATERS TO REACH 5
FT...BUT IT WILL LIKELY BUILD TO THIS LEVEL BY LATE THIS EVENING
AS WELL. THEREFORE...A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS HAS
BEEN ISSUED FOR THE OUTER WATERS AND NANTUCKET SOUND FR THIS
EASTERLY SWELL.
OTHERWISE...WINDS WILL GENERALLY REMAIN BELOW 25 KT THROUGH THE
PERIOD...HOWEVER A COLD FRONT WILL CROSS THE WATERS TONIGHT WITH
THE CHANCE FOR SOME BRIEF 20-30 KT GUSTS IN SHOWERS AND ISOLATED
THUNDERSTORMS...THE BEST CHANCE WILL BE SOUTHERN WATERS.
OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY...MODERATE CONFIDENCE.
MONDAY AND TUESDAY...MODERATE CONFIDENCE. DIMINISHING WINDS AND
SEAS AS HIGH PRESSURE BUILDS. NO HEADLINES ARE ANTICIPATED.
WEDNESDAY...MODERATE CONFIDENCE.
WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT LEVELS.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 8 PM THIS EVENING
TO 8 AM EDT SUNDAY FOR ANZ232-251-256.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT SUNDAY
FOR ANZ250-254-255.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...BELK/DOODY
SHORT TERM...DOODY
LONG TERM...BELK
AVIATION...DOODY/BELK
MARINE...DOODY/BELK
AREA FORECAST DISCUSSION
NWS MIAMI FL
1000 AM EDT SAT SEP 22 2012
.UPDATE...
A LARGE AREA OF HEAVY RAIN CONTINUES TO INCH NORTH ALONG THE EAST
COAST AND METRO AREAS OF SOUTH FLORIDA THIS MORNING. SOME AREAS
HAVE ALREADY RECORDED AMOUNTS INTO THE 2 TO 4 INCH RANGE. REPORTS
FROM THE MIAMI BEACH POLICE REPORTED FLOODING ALONG CHASE AVENUE
FROM ARTHUR GODFREY ROAD/WEST 41ST STREET TO ALTON ROAD WITH WATER
NEAR THE HOOD OF VEHICLES ON 20TH STREET WEST OF ALTON.
BASED ON THE LATEST RADAR TRENDS...RAINFALL RATES HAVE TRENDED
DOWN ACROSS MIAMI-DADE AND BROWARD WITH THE BEST RAINFALL RATES
NOW INCHING NORTH INTO PALM BEACH COUNTY WHERE RAINFALL AMOUNTS
HAVE ALREADY REACHED THE 1-1.5 INCH RANGE OVER THE PAST COUPLE OF
HOURS.
FOR THE REMAINDER OF THE DAY...THE LATEST HRRR RUN HAS INITIALIZED
WELL WITH THE CURRENT RAINFALL COVERAGE AND GENERALLY INDICATES A
LARGE PORTION OF THE LOCAL AREA GOING INTO A LULL THROUGH NOON AND
INTO THE EARLY AFTERNOON PERIOD BEFORE ANOTHER BATCH OF HEAVY RAIN
DEVELOPS AND SPREADS OVER THE AREA THROUGH THE MID-AFTERNOON
THROUGH THE EVENING HOURS ONCE AGAIN. AS A RESULT...FLOODING WILL
REMAIN THE MAIN CONCERN TODAY AS SOILS REMAIN SATURATED FROM
PREVIOUS RAINS. THE LATEST GRIDDED DATABASE HAS BEEN UPDATED WITH
THESE LATEST TRENDS AND NO OTHER UPDATES ARE NECESSARY AT THIS
TIME. 85/AG
&&
.PREV DISCUSSION... /ISSUED 744 AM EDT SAT SEP 22 2012/
AVIATION...
LARGE SHIELD OF SHRAS/TSRAS CONTINUE TO STREAM TO THE NORTH FROM THE
KEYS. A DEEP MOISTURE FIELD ALONG WITH A PASSING SURFACE TROUGH JUST
WEST OF THE FLORIDA KEYS WILL KEEP SHRAS AND EMBEDDED TSRA ACROSS
MUCH OF THE AREA THROUGH THE MORNING HOURS. PREVAILING MVFR
CONDITIONS ARE EXPECTED AT KTMB...KMIA...KOPF AND TOWARDS KFLL FOR
THE NEXT COUPLE OF HOURS AS THESE SHOWERS AND STORMS MOVE NORTH.
VIS/CIGS COULD DROP TO 1SM/1.5KFT IN THE HEAVIER THUNDERSTORMS.
CONTINUED WITH VCTS IN THE AFTERNOON AS A WEAK MID LEVEL
SHORTWAVE SWEEPS ACROSS SOUTH FLORIDA DURING THE PEAK HEATING
HOURS FURTHER ENHANCING SCATTERED TO WIDESPREAD TSRA DEVELOPMENT.
PREV DISCUSSION... /ISSUED 356 AM EDT SAT SEP 22 2012/
LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO S
ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN UPPER
LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE ATMOSPHERIC
MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE MAY NEAR THE
AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH GUIDANCE.
MARINE...
EASTERLY WINDS LESS THAN 15 KNOTS WILL PERSIST THROUGH THE PERIOD
WITH WEEKEND WITH SEAS 4 FEET OR LESS.
FIRE WEATHER...NO CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 86 74 88 74 / 80 50 40 30
FORT LAUDERDALE 85 75 88 76 / 80 50 40 30
MIAMI 87 75 88 75 / 90 50 40 30
NAPLES 84 73 88 73 / 80 30 30 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
943 AM EDT SAT SEP 22 2012
.SYNOPSIS...
WEAK HIGH PRESSURE WILL REMAIN OVER THE REGION TODAY. A COLD FRONT
WILL MOVE ACROSS THE AREA LATE TONIGHT INTO EARLY SUNDAY. HIGH
PRESSURE WILL THEN PREVAIL ACROSS THE EASTERN SEABOARD THROUGH
MUCH OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
VERY FEW CHANGES WERE MADE FOR THE LATE MORNING UPDATE. SURFACE
HIGH PRESSURE CENTERED JUST SOUTH OF THE NORTH CAROLINA CRYSTAL
COAST WILL SHIFT FARTHER OUT INTO THE ATLANTIC TODAY AS A LARGE
LONGWAVE TROUGH REMAINS STATIONARY ACROSS THE EASTERN THIRD OF THE
UNITED STATES. AREAS OF FOG ACROSS PORTIONS OF FAR INTERIOR
SOUTHEAST GEORGIA HAVE GENERALLY DISSIPATED AND EXPECT MAINLY
SUNNY SKIES TO DOMINATE THIS MORNING BEFORE A SHALLOW CUMULUS
FIELD MATERIALIZES DURING THE EARLY AFTERNOON HOURS. A PESKY
CIRRUS CANOPY BEING ENHANCED BY THE RIGHT ENTRANCE REGION OF THE
UPPER JET IS EDGING EVER SO SLOWLY OFFSHORE AND THIS TREND SHOULD
CONTINUE THIS AFTERNOON PER LATEST RAP 400-300MB LAYERED MOISTURE
FIELDS. A MOSTLY SUNNY TO PARTLY CLOUDY SKY CHARACTER WILL WORK
THROUGH SUNSET.
A WEST TO SOUTHWEST FLOW RETURN FLOW AT THE SURFACE AND ALOFT WILL
RESULT IN LIMITED MOISTURE TODAY...INSUFFICIENT TO SUPPORT ANY
PRECIPITATION. A SLIGHT DOWNSLOPE COMPONENT TO THE WINDS COMBINED
WITH COMPRESSIONAL HEATING AHEAD OF THE APPROACHING FRONT SHOULD
PUSH HIGH TEMPERATURES INTO THE UPPER 80S TO AROUND 90 INLAND FROM
THE COAST...WHERE A DEVELOPING ONSHORE FLOW SHOULD KEEP HIGHS IN
THE LOWER TO MID 80S CLOSER TO THE COAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/...
A COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS EVENING...THEN
SHIFT ACROSS THE AREA LATE TONIGHT. MOISTURE RETURN AHEAD OF THE FRONT WILL
BE VERY LIMITED DUE TO A WESTERLY FLOW ALOFT...GENERALLY RESULTING
IN A DRY FRONTAL PASSAGE. THE EXCEPTION MAY BE UP ACROSS PARTS OF
THE CHARLESTON TRI-COUNTY AREA WHERE LOW LEVEL CONVERGENCE AND
FORCING WILL BE GREATEST AND COULD PERHAPS SUPPORT A FEW ISOLATED
SHOWERS OVERNIGHT. LOWS WILL GENERALLY BE IN THE LOWER TO MID 60S
AWAY FROM THE IMMEDIATE COAST.
A COLD FRONT WILL CONTINUE TO PROGRESS EAST OF THE AREA SUNDAY
ALLOWING A DRIER AIR MASS TO MOVE IN FROM THE WEST. THIS COOL AND
DRY AIR MASS WILL REMAIN OVER THE AREA THROUGH TUESDAY. TEMPERATURES
WILL BE AT OR BELOW NORMAL WITH HIGHS GENERALLY IN THE LOWER 80S AND
OVERNIGHT LOWS IN THE LOWER TO MID 50S /POSSIBLY EVEN SOME UPPER 40S
ESPECIALLY TUESDAY MORNING IN THE NORMALLY COOLER INLAND AREAS/.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
CONFIDENCE IS HIGH THROUGH MID WEEK BUT DIMINISHES THEREAFTER.
HIGH PRESSURE IS EXPECTED TO KEEP CONDITIONS MOSTLY DRY THROUGH
MID WEEK WITH THE BEST CHANCE OF SHOWERS REMAINING
OFFSHORE...ALTHOUGH SOME COULD PUSH ASHORE ALONG THE GEORGIA
COAST. BY FRIDAY A BACKDOOR COLD FRONT WILL TRY TO PUSH SOUTH
TOWARD THE AREA AS AN UPPER SHORTWAVE TROUGH OF LOW PRESSURE
PUSHES OFF THE NEW ENGLAND COAST AND THUS HAVE SOME SMALL RAIN
CHANCES TO ACCOUNT FOR THIS FEATURE. TEMPERATURES WILL START OFF
BELOW NORMAL WEDNESDAY MORNING BUT MODERATE TOWARD THE END OF THE
WEEK BEFORE POSSIBLY RETURNING CLOSER TO NORMAL BY THE END OF THE
PERIOD.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
VFR. A COLD FRONT WILL MOVE THROUGH OVERNIGHT WITH WINDS BECOMING
NORTHWEST LATE BUT THE LACK OF MOISTURE MEANS RAIN CHANCES/SUB-VFR
CONDS ARE VERY LOW.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS EXPECTED
THROUGH NEXT THURSDAY.
&&
.MARINE...
HIGH PRESSURE WILL PREVAIL OVER THE WATERS THIS MORNING...BEFORE
BECOMING DISPLACED OFFSHORE THIS AFTERNOON INTO THIS EVENING BY A
COLD FRONT APPROACHING FROM THE NORTHWEST. THE FRONT WILL THEN
ADVANCE ACROSS THE WATERS LATE TONIGHT. OVERALL...LIGHT/VARIABLE
WINDS THIS MORNING WILL BECOME MORE SOUTHERLY LATER TONIGHT AND
THIS EVENING AS A RETURN FLOW DEVELOPS. THEN...WINDS SHOULD SHIFT
WEST AND EVENTUALLY NORTHWEST OVERNIGHT AS THE FRONT PUSHES
OFFSHORE. A WEAK SURFACE PRESSURE GRADIENT WILL KEEP WINDS LESS
THAN 15 KT THROUGH TONIGHT...WITH SEAS NO GREATER THAN 2 OR 3 FT.
SUNDAY THROUGH THURSDAY...CONDITIONS WILL GO DOWNHILL SUNDAY NIGHT
AS A MUCH COOLER AND DRIER HIGH PRESSURE AREA MOVES IN FROM THE
NORTHWEST. WINDS SHOULD MOSTLY REMAIN BELOW ADVISORY LEVELS BUT A
NORTHEAST FLOW WILL CAUSE SEAS TO BUILD TO ADVISORY LEVELS AT LEAST
BEYOND 20 NM BEGINNING MONDAY AND LASTING INTO TUESDAY.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...RJB/JAQ
LONG TERM...RJB
AVIATION...
MARINE...
AREA FORECAST DISCUSSION
NWS DES MOINES IA
622 AM CDT SAT SEP 22 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
MAIN FORECAST CONCERN IS WITH WINDS AND TEMPS
TODAY WITH STRONG CAA DEVELOPING BEHIND THE COLD FRONT THAT PUSHED
ACROSS MUCH OF THE CWA EARLY THIS MORNING. LEANED TOWARD A
NAM/RAP/SREF BLEND TODAY AS ALL MODELS ARE IN GOOD AGREEMENT. 03Z
HRRR/05Z RAP DEPICT A STRATUS DECK LOCATED IN NORTHERN MN TO ARRIVE
IN NORTHERN IOWA BY AROUND 12Z AND THEN DISSIPATE BY AROUND 18Z.
INCREASED CLOUD COVER OVER THE NORTH TO NORTHEAST THIS MORNING AS A
RESULT. THIS WILL HINDER THE MAX TEMP SLIGHTLY AND WENT A LITTLE
COOLER IN THIS AREA. OTHERWISE...STRONG NORTHWEST WINDS WILL BE
COMMON THROUGHOUT THE DAY WITH FAIRLY TIGHT PRESSURE GRADIENT AND
DECENT MIXING BEFORE HIGH SETTLES IN LATE THIS AFTERNOON. TWEAKED
WINDS UP SLIGHTLY WITH THIS SCENARIO AS CURRENT WINDS UPSTREAM ARE
GUSTING TO 20-25KTS.
.LONG TERM /TONIGHT THROUGH FRIDAY/...
COLD CANADIAN HIGH PRESSURE WILL INTO CENTRAL IOWA TONIGHT. THE HIGH
WILL REINFORCE THE VERY DRY AIR THAT IS FELTING INTO THE STATE THIS
MORNING AND EXPECT DEWPOINTS OVERNIGHT TO BE WELL INTO THE 20S OVER
THE NORTH AND WEST. CURRENTLY A LARGE ARE OF STRATUS ALONG THE
EASTERN FRINGE OF THE HIGH THUS THERE IS SOME UNCERTAINTY THAT THIS
STRATUS MAY AFFECT AREAS EAST OF INTERSTATE 35 OVERNIGHT AND PROVIDE
ENOUGH INSOLATION TO HOLD READINGS UP. 925 MB WIND TRAJECTORIES
REMAIN ROUGHLY 340-360 DEGREES THROUGH TODAY AND TONIGHT. MUCH OF
THE REGION SHOULD HAVE ENOUGH SUBSIDENCE WITH THE APPROACHING HIGH
TO ERODE MUCH OF IT. FOR AREAS THAT HAVE MOSTLY CLEAR SKIES...THE
DIMINISHING WINDS AND VERY DRY AIR WILL ALLOW TEMPERATURES TO
PLUMMET OVERNIGHT TO RECORD OR NEAR RECORD LOW VALUES. THESE VALUES
ARE BELOW FREEZING FOR ALL LOCATIONS EXCEPT THE FAR SOUTH AND
SOUTHEAST. HAVE ISSUED A FREEZE WARNING FOR ALL LOCATIONS WITH
FORECAST LOWS BELOW 32 TONIGHT. HAVE LEFT THE FREEZE WATCH OUT FOR
THE SOUTH CENTRAL WHERE READINGS WILL BE A BIT WARMER. GIVEN THE
VERY DRY AIR...FROST MAY NOT BE PREVALENT IN THESE AREAS DESPITE THE
TEMPERATURES SO NO CONFIDENCE IN FROST HEADLINES IN THAT REGION.
KEEPING THE FREEZE WATCH WILL GIVE THE FOLLOWING SHIFT SOME WIGGLE
ROOM WITH THE HEADLINES IF MORE COLD AIR THAN ANTICIPATED ARRIVES BY
TONIGHT.
SUNDAY WILL BE PLEASANT THOUGH COOL WITH MOSTLY SUNNY SKIES AND
LIGHT NORTHWEST WINDS. HIGH PRESSURE SLIDES TO THE SOUTHEAST SUNDAY
NIGHT. WILL HAVE QUICK COOLING SUNDAY EVENING BEFORE SOUTHERLY FLOW
GRADUALLY RETURNS LATE. POSSIBLE FOR NEAR FREEZING TEMPERATURES
AGAIN OVER THE NORTHEAST WHERE RETURN FLOW WILL ARRIVE LAST.
READINGS WILL BE MILD MONDAY AND TUESDAY WITH 850 MB THERMAL RIDGING
MOVES INTO THE STATE. MORE UNCERTAINTY ARRIVES FOR WEDNESDAY THROUGH
FRIDAY WITH THE TRANSITION FROM NORTHWEST TO ZONAL FLOW OCCURS. THE
TRANSITION WILL ALLOW THE ENERGY FROM WEST COAST UPPER LOW AND A
PACIFIC NORTHWEST SYSTEM TO MOVE TOWARD THE REGION WHILE A MID LEVEL
BOUNDARY LIFTS TOWARD THE STATE. CURRENTLY HAVE SEVERAL PERIODS WITH
POPS WITH THE BEST POTENTIAL WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
THE 500 MB FLOW DURING THIS PERIOD IS UNORGANIZED ENOUGH THAT IT IS
GIVING GUIDANCE PROBLEMS ON EXACT PLACEMENT OF WHERE THE SHORTWAVES
WILL MOVE THROUGH.
&&
.AVIATION...22/12Z
CONCERNED ABOUT MVFR STRATUS QUICKLY DROPPING SOUTH INTO NORTHERN
IOWA THIS MORNING AND HAVE ENOUGH CONFIDENCE TO MENTION AT FOD/MCW
B/T 13-14Z WHEN IT SHOULD ARRIVE. QUESTIONABLE HOW FAR SOUTH THE
REACH OF THE STRATUS DECK WILL GO...BUT MAY GET AS FAR SOUTH AS
ALO...BUT LIKELY NOT AT DSM AND OTM. HAVE THE STRATUS DISSIPATING BY
17-18Z. WINDS WILL INCREASE LATER THIS MORNING AND PERSIST THROUGH
THE AFTERNOON BEFORE DECOUPLING AROUND 00Z SUNDAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING LATE TONIGHT THROUGH SUNDAY MORNING FOR
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-
WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-
GREENE-BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-CASS-
ADAIR-ADAMS-TAYLOR-
FREEZE WATCH LATE TONIGHT THROUGH SUNDAY MORNING FOR
POLK-JASPER-POWESHIEK-MADISON-WARREN-MARION-MAHASKA-UNION-CLARKE-
LUCAS-MONROE-WAPELLO-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
806 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TODAY, BRINGING THE CHANCE OF
SHOWERS ACROSS THE AREA. AN UPPER LEVEL DISTURBANCE WILL PUSH THE
FRONT EAST OF THE AREA BY TONIGHT, USHERING MUCH COOLER AIR INTO THE
AREA FOR SUNDAY INTO MONDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST WV SAT IMAGERY AND RAP MID-LEVEL ANALYSIS INDICATE A
CLOSED 500MB LOW CENTERED NORTH OF THE GREAT LAKES IN ONTARIO. AN
INITIAL, WEAK MID-LEVEL VORT MAX THAT WAS CO-LOCATED WITH A 60KT
925MB JET AND SURFACE LOW WEAKENED AS IT SHIFTED FROM OHIO INTO NW
PA. FURTHER UPSTREAM, A STRONG VORT IS CENTERED ALONG THE
WISCONSIN/MINNESOTA BORDER AND IS SHIFTING INTO THE WESTERN GREAT
LAKES. AT THE SURFACE, A 1006MB LOW HAS SHIFTED INTO WESTERN NY WITH
A FRONTAL BOUNDARY EXTENDING SOUTHWEST OF THIS FEATURE. THE
BOUNDARY EXTENDS FROM FRANKLIN TO PITTSBURGH TO PARKERSBURG, WV.
NUMEROUS SHOWERS CONTINUE TO SLIDE NORTHEASTWARD ALONG THE
BOUNDARY.
TODAY...THE SURFACE LOW WILL CONTINUE TO LIFT NORTH OF THE AREA
WITH ITS ASSOCIATED TROUGH AND FRONTAL BOUNDARY SLIDING
SOUTHEASTWARD ACROSS WESTERN PA AND NORTHERN WV BETWEEN 12Z AND
18Z. THIS WILL ALLOW FOR THE CHANCE OF SHOWERS TO CONTINUE INTO THE
EARLY AFTERNOON. A BRIEF RESPITE IN SHOWERS WILL BE POSSIBLE
ACROSS MUCH OF THE AREA DURING THE LATE MORNING INTO EARLY
AFTERNOON HOURS. THE AFOREMENTIONED UPPER MIDWEST-BASED VORTEX WILL
SWING AROUND THE BASE OF THE TROUGH ACROSS THE OHIO VALLEY,
SERVING TO AMPLIFY THE TROUGH AS IT SLIDES INTO WESTERN PA.
FORCING WITH THIS FEATURE WILL INCREASE POP CHANCES BY AROUND,
WITH LIKELY POPS NORTH OF PITTSBURGH BY 00Z SUNDAY.
TEMP FORECAST IS A BIT CHALLENGING AS SKIES WILL BECOME CLOUDY
TODAY WITH THE COLD FRONT PUSHING INTO THE AREA. AHEAD OF THE
FRONT, WAA WILL OCCUR EARLY IN A SOUTHWESTERLY LOW-LEVEL FLOW.
THIS WILL ALLOW TEMPS IN NORTH-CENTRAL WV AND SOUTHWEST PA TO WARM
INTO THE LOWER 70S EARLY BEFORE SHOWERS MOVE INTO THE AREA AND THE
FRONT COOLS TEMPS BACK INTO THE 60S BY LATE AFTERNOON INTO THE
EVENING.
TONIGHT...THE STRONG VORT ENERGY WILL SLIDE NORTHEAST OF THE AREA
WITH COLD AIR ADVECTION ENSUING AS THE COLD FRONT FINALLY EXITS EAST
OF THE AREA. A MOIST NORTHWESTERLY LOW-LEVEL FLOW WITH CAA SUPPORTS
THE CHANCE OF SHOWERS CONTINUING NORTH OF I-70 OVERNIGHT. TEMPS WILL
DROP OFF QUICKLY OVERNIGHT, WITH LOWS A FEW DEGREES COOLER THAN A
MAV/MET BLEND, COOLING TO THE LOWER TO MID 40S ACROSS THE AREA.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
AN OPERATIONAL MODEL CONSENSUS INDICATES THAT THE MID-LEVEL TROUGH
WILL SHIFT FROM THE GREAT LAKES REGION ON SUNDAY INTO THE UPPER
OHIO VALLEY SUNDAY NIGHT. THE AXIS OF THE TROUGH WILL BE CENTERED
OVER THE AREA BY 12Z MONDAY AND QUICKLY SHIFT EASTWARD ON MONDAY.
COLD AIR ADVECTION WILL BE ONGOING IN THE WAKE OF THE COLD FRONT
ON SUNDAY AND SUNDAY NIGHT. THIS IN COMBINATION WITH LOWERING
500MB HEIGHTS, VORT ENERGY ROTATING AROUND THE TROUGH, AND A MOIST
WEST-NORTHWESTERLY LOW-LEVEL FLOW WILL ALLOW FOR THE CHANCE OF
SHOWERS TO CONTINUE NORTH OF PITTSBURGH THROUGH THE DAY ON SUNDAY.
POPS DIMINISH SUNDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE
WEST. WITH 850MB TEMPS COOLING TO 1-3C AND MOSTLY CLOUDY SKIES,
FORECAST IS CLOSEST TO THE COOLER MAV GUIDANCE WITH TEMPS
STRUGGLING TO MAKE IT TO THE 60 DEGREE MARK ACROSS THE AREA FOR
HIGHS ON SUNDAY. CLEARING FROM THE WEST ALONG WITH NEAR CALM WINDS
WILL AID IN RADIATIONAL COOLING SUNDAY NIGHT. LOWS WILL BE AROUND
10 DEGREES BELOW NORMAL. PATCHY FROST IS FORECAST TO DEVELOP NEAR
DAWN ACROSS THE EASTERN RIDGES AND A FROST ADVISORY MAY BE NEEDED
FOR THIS PERIOD.
HIGH PRESSURE WILL SHIFT FROM THE OHIO VALLEY INTO THE MID-
ATLANTIC MONDAY INTO EARLY TUESDAY, ALLOWING FOR A DRY FORECAST
THROUGH THIS PERIOD. SCHC POPS ARE INTRODUCED LATE ON TUESDAY AS
MOISTURE INCREASES AHEAD OF THE NEXT COLD FRONT. ECMWF IS A LITTLE
FASTER WITH PRECIP THAN THE GFS SO STILL SOME UNCERTAINTY WITH THE
TIMING OF THE ONSET OF ANY SHOWERS. DESPITE MORE ABUNDANT SUNSHINE
ON MONDAY, WITH THE COOL, CANADIAN AIR MASS SETTLED INTO THE AREA,
HIGHS WILL BE AROUND 10 DEGREES BELOW NORMAL. TEMPS WILL MODERATE
CLOSER TO SEASONAL NORMALS ON TUESDAY AS THE LOWER-LEVEL FLOW
SHIFTS TO MORE SOUTHERLY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
THE DETERMINISTIC MODELS THEN HAVE A SHORTWAVE DIGGING SOUTHWARD
OVER THE GREAT LAKES. THE GFS IS FASTER THAN THE ECMWF BUT HAS
SLOWED IN THE 12Z RUN. WITH THIS...OPTED TO TAKE A BLEND OF THE
00Z ECMWF/12Z GFS... WHICH SHOWS PRECIPITATION WITH THE FRONT
LATER WEDNESDAY THROUGH THURSDAY. ONCE THE FRONT CROSSES...HIGH
PRESSURE LOOKS TO BUILD OVER MUCH OF THE GREAT LAKES/MIDWEST.
COOL TEMPERATURES ALOFT WITH THE TROUGH SITUATED OVER CANADA WILL
HELP TO KEEP TEMPERATURES AROUND NORMAL FOR THIS TIME OF YEAR.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
PER RECENT SURFACE AND SATELLITE DATA...COUPLED WITH GFS LAMP AND
NAM MODEL PROFILES...EXPECT POSTFRONTAL STRATOCUMULUS CEILINGS
ACROSS THE UPPER OHIO VALLEY TO BE MAINLY MVFR THIS MORNING WITH
SOME LOWERING TO IFR AT TIMES.
VERTICAL MIXING SHOULD INCREASE ENOUGH BY AFTERNOON SO THAT MOST
CEILINGS WILL BE VFR.
RECENT HIGH-RESOLUTION MODEL OUTPUT SHOWS A SECOND COLD FRONT MOVING
SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY EARLY TONIGHT. EXPECT A
FRONTAL BAND OF MVFR SHOWERS FOLLOWED BY SOME LATE NIGHT IFR
CONDITIONS DUE TO EVAPORATING RAIN INTO A COOLING SURFACE LAYER.
SURFACE WINDS WILL BE FROM THE SOUTHWEST 5 TO 10 KTS THIS MORNING
THEN VEER INTO THE WEST AT 10 KTS WITH GUSTS TO 20 KTS THIS
AFTERNOON...AND THEN NORTHWEST TONIGHT.
.OUTLOOK /SUNDAY THROUGH WEDNESDAY/...
COLD POOL STRATOCUMULUS AND INSTABILITY SHOWERS CAN CONTINUE TO
CAUSE RESTRICTIONS AT TIMES SUNDAY. HIGH PRESSURE SUBSIDENCE WILL
FOLLOW WITH VFR MONDAY AND TUESDAY. NEXT FRONTAL SYSTEM
APPROACHES THE AREA ON WEDNESDAY WITH POSSIBLE RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
752 AM EDT SAT SEP 22 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 525 AM EDT SAT SEP 22 2012
1004MB SFC LOW IS CURRENTLY JUST TO THE EAST OF LK SUPERIOR AND
LOCATED ON THE EASTERN EDGE OF THE PERSISTENT UPPER TROUGH THAT HAS
BEEN OVER THE UPPER GREAT LAKES REGION. THERE ARE A COUPLE
SHORTWAVES OF NOTE THAT WILL BE AFFECTING THE AREA TODAY AND
TONIGHT. THE FIRST WAVE IS LOCATED OVER NW WI AND DROPPING TO THE
SE. THIS HAS PRODUCED SCATTERED SHOWERS OVER FAR WESTERN UPPER
MICHIGAN AND LK SUPERIOR. AS THIS SHORTWAVE HAS STARTED TO SLIDE TO
THE S...A SFC TROUGH STRETCHING E TO W ACROSS SRN LK SUPERIOR HAS
ALSO BEEN SLIDING S AND HELPED PRODUCE A FEW SHOWERS AND AN ISOLATED
THUNDERSTORM. WINDS ARE QUICKLY TURNING TO THE N AND GUSTING TO
25KTS BEHIND THIS TROUGH. THE OTHER SHORTWAVE IS LOCATED OVER NW
ONTARIO AND QUICKLY DROPPING SOUTH.
TODAY...SHORTWAVE DIVING SE THROUGH WI THIS MORNING HAS STARTED TO
USHER IN COLDER H850 TEMPS OVER THE AREA TODAY...WITH RUC ANALYZED
VALUES FALLING FROM AROUND 0 TO -1C AT 00Z TODAY TO -2 TO -3C AT
08Z. THESE COOLER TEMPS ALOFT AND ADDITIONAL MOISTURE BEHIND THE
FIRST SHORTWAVE MOVING THROUGH NW WI THIS MORNING WILL LEAD TO AN
UPTICK IN LK ENHANCED SHOWERS THIS MORNING...ESPECIALLY ALONG AND
RIGHT BEHIND THE SFC TROUGH. BUT A POCKET OF DRIER H850-700 MOISTURE
OVER THE WESTERN CWA SHOULD KEEP THE SHOWERS OVER THE WEST FROM
BECOMING TOO WIDESPREAD AND STRONG. THEY MAY EVEN END DURING THE
LATE MORNING AND EARLY AFTERNOON...AS THERE IS LIMITED MOISTURE SEEN
TOWARDS THUNDER BAY AND SRN ONTARIO. MODELS ARE SHOWING ENOUGH
SHALLOW MOISTURE TO SUPPORT AT LEAST LK ENHANCED CLOUDS DURING THAT
DRIER PERIOD. FARTHER EAST...DEEPER MOISTURE IS IN PLACE UNDER THE
UPPER TROUGH AND WITH THE COLD AIR ALOFT...EXPECT LK ENHANCED
SHOWERS TO BECOME MORE WIDESPREAD THROUGH THE DAY. THEN AS THE
SECONDARY SHORTWAVE...CURRENTLY IN NW ONTARIO...ARRIVES IN THE
MID-LATE AFTN AND CONTINUES INTO THE EVENING WITH THE CONTINUED
COOLING ALOFT...EXPECT LK ENHANCED SHOWERS AIDED BY THE SHORTWAVE TO
REALLY TAKE OFF ACROSS ALL BUT THE SCNTRL CWA.
THE BIGGEST ISSUE FOR TODAY MAY BE POTENTIAL FOR THUNDER AND
GRAUPEL. THE COLD AIR ALOFT WILL HELP STEEPEN LLVL LAPSE RATES AND
LEAD TO STRONGER UPDRAFTS. BUFKIT LK INDUCED CAPE VALUES HAVE BEEN
FAIRLY IMPRESSIVE...500-1250 J/KG...BUT MODIFYING SOUNDINGS TO LOW
50S OVER LOW-MID 40S WOULD INDICATE CAPES STAYING IN THE 300-500
J/KG RANGE. OVER THE LAST COUPLE DAYS IT SEEMS THE LIGHTNING HAS
OCCURRED WHERE ADDITIONAL FORCING HAS BEEN PRESENT
/E.G. SHORTWAVE...CONVERGENCE ALONG FRONT/. THUS...EXPECT A
LULL IN THUNDER CHANCES AFTER THE TROUGH MOVES THROUGH AND
THEN REDEVELOP TOWARDS AFTN WHEN SHORTWAVE ARRIVES AND PEAK HEATING
IS HERE. AS FOR GRAUPEL...WILL CONTINUE TO MENTION POTENTIAL WITH
THE STRENGTH OF THE UPDRAFTS. PUSHED THE PROBABILITIES UP HEADING
INTO THE AFTN WITH THE APPROACHING SHORTWAVE AND DEEPER MOISTURE.
AS FOR WINDS...H950-850 WINDS ARE GENERALLY IN THE 30-35KT
RANGE...SO EXPECT GALES TO 35-37KTS TO BE THE NORM. THINKING WITH
LITTLE VARIABILITY IN THE WINDS IN THAT LAYER AND THE STRONG
PRESSURE GRADIENT...IT WILL LIKELY BE SUSTAINED WINDS TOWARDS
25-30KTS AND THEN GUSTS TOWARDS THAT 35KT RANGE. WITH LITTLE
ADDITIONAL SUPPORT FROM ISALLOBARIC FEATURES...DON/T EXPECT THE
GUSTS TO GET MUCH HIGHER THAN THE MODELS ARE SHOWING OVER ERN LK
SUPERIOR AND SHOULDN/T REACH ADVY CRITERIA NEAR THE LAKESHORE OVER
ALGER/LUCE COUNTIES.
TONIGHT...TIGHT PRESSURE GRADIENT WILL SHIFT SE OF THE CWA...AS HIGH
PRESSURE OVER THE NRN PLAINS BEGINS TO SLOWLY APPROACH THE AREA. THE
SHORTWAVE THAT ARRIVES OVER THE NW HALF OF THE CWA IN THE AFTN WILL
PUSH THROUGH THE CWA DURING THE EVENING HOURS. WILL KEEP HIGHER
POPS OVER LOCATIONS NEAR LAKE SUPERIOR DURING THE EVENING HOURS
DUE TO LK ENHANCEMENT. AS THE SHORTWAVE MOVES SE OF THE CWA...EXPECT
A TRANSITION TO JUST LK ENHANCED SHOWERS WITH H850 TEMPS AROUND -3
TO -4C. DRYING ALOFT FROM THE HIGH WILL ALLOW THE LK ENHANCED
SHOWERS TO BECOME FOCUSED FARTHER EAST WHERE THE DEEPEST MOISTURE
REMAINS THROUGH THE NIGHT. STILL THINK THERE WILL BE ENOUGH
MOISTURE FOR SCATTERED SHOWERS OUT WEST WITH THE SHORTER FETCH.
COULD BE SOME DECENT RAINS OVER THE ERN CWA DEPENDING ON WHERE THE
SHOWERS LINE UP. APPEARS TO BE SOME ENHANCED CONVERGENCE IN THAT
AREA WITH THE APPROACHING HIGH...NNW OVER THE FAR ERN LK AND
BACKING TO THE NW-WNW OVERNIGHT OVER WRN LK SUPERIOR. WITH THE
VERY DEEP CLOUD/CONVECTIVE LAYER...COULD EASILY SEE AREAS TOWARDS
MUNISING ENDING UP WITH OVER AN INCH OF RAIN BY SUNDAY MORNING.
WILL LEAVE A SLIGHT CHANCE MENTION OF SNOW IN OVER THE
WRN CWA...BUT MODEL SOUNDING PROFILES SHOW A COUPLE FEATURES
LIMITING POTENTIAL. FIRST...BEST LLVL FORCING COINSIDING WITH THE
CLOUD LAYER IS IN THE -1 TO -5C TEMP RANGE...WHICH LIMITS ICE IN
THE CLOUD. SECOND...WBZ VALUES IN THE 1200-1500 FT RANGE WOULD
INDICATE ONLY A LOW POTENTIAL FOR SNOW TO MAKE IT TO THE SFC IF
THERE IS ACTUALLY ICE/SNOW PRESENT IN THE CLOUD. BUT IF GFS
SOUNDINGS ARE CORRECT WITH A SLIGHTLY COLDER AND DEEPER CLOUD
DEPTH...SNOW WOULD BE MORE LIKELY.
AS FOR WATERSPOUTS OVER THE LAKES TODAY AND TONIGHT...SWI INDICATES
VERY FAVORABLE CONDITIONS...APPROACHING 7-9...DUE TO DEEP CONVECTIVE
LAYER AND SFC-850 DELTA-T VALUES AROUND 15-17. THE ONLY DRAWBACK IS
THE STRONG WINDS THIS AFTN. WITH H850 WINDS AROUND 30-35KTS...THIS
IS ON THE HIGH END FOR WATERSPOUT POTENTIAL THROUGH THE DAY TODAY.
IF WINDS END UP A LITTLE LOWER THAN EXPECTED...COULD SEE POTENTIAL
INCREASE. WITH WINDS DECREASING TONIGHT...HAVE ADDED THE POTENTIAL
BACK OVER THE ERN HALF OF LK SUPERIOR...ESPECIALLY WITH THE ADDED
CONVERGENCE AND EXPECTED AREA OF STRONGER SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 525 AM EDT SAT SEP 22 2012
MEDIUM RANGE GUIDANCE IS IN GENERAL AGREEMENT ON THE BIG PICTURE
OVER THE NEXT 7 DAYS. CURRENT COOL PATTERN FOR UPPER MI WILL PEAK
TODAY/SUN AS TROF REACHES PEAK AMPLITUDE. COOL WEATHER WILL CONTINUE
INTO THE EARLY PART OF THE UPCOMING WEEK AS RIDGE REMAINS OVER WRN
NAMERICA WITH DOWNSTREAM TROF EXTENDING S THRU THE GREAT LAKES...
THOUGH THERE WILL BE A SHARP WARM UP MON AHEAD OF THE NEXT SHORTWAVE
DROPPING INTO THE TROF. INTO THE MIDDLE/END OF THE WEEK...TROF WILL
WEAKEN/LIFT OUT AS UPSTREAM RIDGE DEAMPLIFIES SOME AND PROGRESSES
E...BUT IT APPEARS MORE ENERGY MAY DROP SE INTO THE NE CONUS LATE
WEEK...PREVENTING A MORE SUSTAINED WARMING TREND FROM TAKING HOLD
HERE. HOWEVER...TEMPS WILL STILL RETURN TO MORE TYPICAL LATE SEPT
VALUES. PCPN CHANCES WILL BE HIGHEST TODAY/SUN UNDER THE DEEP TROF
OVER THE AREA. TREND WILL THEN BE TOWARD DRY WEATHER DURING THE
UPCOMING WEEK AS TROF GRADUALLY WEAKENS/DRIFTS E.
BEGINNING SUN...MID/UPPER TROF WILL BEGIN TO SHIFT E...RESULTING IN
SLOWLY RISING HEIGHTS. AT THE LOWER LEVELS...THE UPPER LAKES WILL
REMAIN FIRMLY IN THE THERMAL TROF WITH MODERATION ONLY APPEARING TO
OCCUR DUE TO DAYTIME HEATING. WITH MORNING 850MB TEMPS OF -1 TO -4C
ONLY RISING TO 0 TO -2 BY THE END OF THE AFTN...LAKE EFFECT -SHRA
WILL CONTINUE THRU THE DAY. HOWEVER...RISING HEIGHTS ALONG WITH
ADVECTION OF DRIER AIR AT THE LOW LEVELS AS WINDS BACK MORE W SHOULD
SPELL DIMINISHING SHRA FROM W TO E THRU THE DAY. BEING VERY EARLY IN
THE LAKE EFFECT SEASON...DIURNAL HEATING WILL ALSO DISRUPT LAKE
EFFECT PROCESSES...AIDING THE DIMINISHING TREND. SO...EXPECT
LINGERING NW FLOW LAKE EFFECT SHRA OVER THE W TO END BY EARLY/MID
AFTN. OVER THE E...LAKE EFFECT SHRA WILL DECREASE IN COVERAGE...BUT
NOT LIKELY END UNTIL LATER SUN EVENING WHEN WINDS BACK TO AN
OFFSHORE DIRECTION. WITH DIURNAL MIN SUN MORNING...1000-850MB
THICKNESS BTWN 1305-1310M OVER THE W SUGGEST SOME POTENTIAL FOR SNOW
FLAKES TO MIX WITH THE SHRA OVER THE HIGH TERRAIN. OTHERWISE...
GRAUPEL WILL CONTINUE TO BE THE MAIN FROZEN PTYPE THAT WILL MIX WITH
THE HEAVIER SHRA.
WAA REGIME RAMPS UP ON WESTERLY WINDS SUN NIGHT/MON AHEAD OF THE
NEXT SHORTWAVE TROF WHICH WILL BE DROPPING TOWARD THE UPPER LAKES.
WITH DEPARTURE OF LAKE EFFECT CLOUDS AND BEFORE HIGH CLOUDS ARRIVE
AHEAD OF APPRAOCHING SHORTWAVE AND BEFORE LOW-LEVEL WINDS INCREASE
SUBSTANTIALLY...TEMPS WILL HAVE AN OPPORTUNITY TO FALL QUICKLY UNDER
DRY AIR MASS (PRECIPITABLE WATER 50-60PCT OF NORMAL). FAVORED THE
LOWER SIDE OF GUIDANCE GIVEN THE COOL AFTN SUN. TEMPS WILL PROBABLY
SLIP BLO FREEZING IN MANY INTERIOR LOCATIONS. TIGHT PRES GRADIENT
BTWN SFC HIGH OVER THE OHIO VALLEY AND COLD FRONT DROPPING TOWARD
THE AREA MON WILL LEAD TO A BREEZY/WINDY DAY. 850MB WINDS ARE
PROGGED AT 40-45KT (TO NEAR 50KT ON NAM). EXAMINATION OF FCST
SOUNDINGS SUGGEST MIXED LAYER WILL BUILD SUFFICIENTLY TO TAP SOME OF
THE STRONGER WINDS. GUSTS OF 30-35MPH WILL PROBABLY BE COMMON...BUT
IF THE DAY ENDS UP WITH LESS CLOUDINESS/HIGHER MIXING HEIGHT...COULD
BE TALKING A WIND ADVY TYPE DAY. GIVEN THE DRY ANTECEDENT AIR MASS
AND LACK OF A LOW-LEVEL MOISTURE CONNECTION...SHRA SEEM UNLIKELY
AHEAD OF COLD FRONT. FOR NOW...PLAN TO STAY WITH JUST SLIGHT CHC
POPS OVER THE ERN FCST AREA...CLOSER TO STRONGER DEEP LAYER FORCING.
MAY END UP WITH JUST SOME SPRINKLES IF ANY PCPN DOES OCCUR.
LOW-LEVEL JET TRANSLATING ACROSS THE AREA WILL BRING STRONG WARMING
AS 850MB TEMPS SURGE TO 6-9C BY THE END OF THE AFTN. 60S SHOULD
GENERALLY BE THE RULE FOR MAX TEMPS.
COLD FRONT DROPS THRU THE AREA MON NIGHT. NOT EXPECTING MUCH IF ANY
LAKE EFFECT PCPN BEHIND FRONT UNDER MARGINALLY COLD AIR MASS AS
ANTICYCLONIC FLOW QUICKLY TAKES OVER AFTER FROPA. UNDER N WINDS...
MIGHT SEE A FEW -SHRA IN THE UPSLOPE AREAS NEAR LAKE SUPERIOR MON
NIGHT. DRY WEATHER SHOULD THEN DOMINATE TUE THRU THU AS SFC HIGH
PRES SLOWLY MOVES ACROSS THE UPPER GREAT LAKES. ONE EXCEPTION MAY BE
TUE NIGHT. 850MB TEMPS FALLING TO AROUND -2C MAY ALLOW SOME LAKE
EFFECT -SHRA TO DEVELOP. IN THE INTERIOR...SHOULD SEE A COUPLE OF
COLD NIGHTS (FREEZES) TUE NIGHT/WED NIGHT AS WINDS DIMINISH TO LIGHT
WITH SFC HIGH IN THE VCNTY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 752 AM EDT SAT SEP 22 2012
A WET PERIOD WILL CONTINUE AT THE TAF SITES THROUGH THIS WEEKEND.
WITH COLD TEMPERATURES ALOFT...EXPECT LAKE EFFECT CLOUDS AND RAIN
TO BE ON TAP FOR MUCH OF THE TAF PERIOD. A SURFACE TROUGH DROPPING
SOUTH ACROSS UPPER MI HAS SWITCHED WINDS TO THE NORTH AT ALL OF
THE TAF SITES AND IT COULD GET QUITE GUSTY AT KCMX/KSAW AT TIMES
TODAY.
BEHIND THE TROUGH...EXPECT GRADUALLY LOWERING CIGS THROUGH MVFR
VALUES DURING THE REST OF THE TAF PERIOD. THIS IS DUE TO ADDITIONAL
MOISTURE AND FORCING FROM A SHORTWAVE THAT WILL HELP ENHANCE LK
SHOWERS OFF LK SUPERIOR LATE THIS AFTERNOON AND EVENING. WITH THE
LONGEST FETCH AND BEST MOISTURE...EXPECT THE HEAVIEST SHOWERS TO
OCCUR AT KSAW. HAVE KEPT VSBYS AT VFR AT THIS POINT...BUT COULD SEE
BRIEF PERIODS OF MVFR VSBYS TOO.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 525 AM EDT SAT SEP 22 2012
NORTH TO NORTHWEST GALES TO 35-40KTS ARE EXPECTED TODAY OVER THE
EASTERN HALF OF LAKE SUPERIOR AND CONTINUE INTO TONIGHT. AS HIGH
PRESSURE OVER THE NORTHERN PLAINS BEGINS TO WORK IN TONIGHT...EXPECT
THE WINDS TO SLOWLY DIMINISH. THERE IS A POTENTIAL FOR WATERSPOUTS
TODAY AND TONIGHT...ALTHOUGH THE BEST CHANCE WILL COME TONIGHT AS
THE WINDS DECREASE SOME. A SECONDARY TROUGH DROPPING SOUTHEAST
ACROSS LAKE SUPERIOR MONDAY NIGHT WILL BRING ANOTHER PERIOD OF
GALES. SOUTHWEST WINDS AHEAD OF THIS FRONT SHOULD REACH GALES TO
35KTS BY LATE SUNDAY NIGHT AND CONTINUE INTO MONDAY UNTIL THE TROUGH
MOVES THROUGH. BEHIND THE TROUGH...HIGH PRESSURE WILL SETTLE OVER
THE UPPER GREAT LAKES REGION FOR TUESDAY AND WEDNESDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 11 AM THIS MORNING TO 11 PM EDT THIS EVENING
FOR LSZ251-267.
GALE WARNING UNTIL 1 AM EDT SUNDAY FOR LSZ244-245-248>250-
264>266.
GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...SRF
MARINE...SRF
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
910 AM MDT SAT SEP 22 2012
.SHORT TERM...VALID FOR TDY AND SUN...
UPDATE TO ZFP AND WRKAFP. MADE JUST SOME SMALL TWEAKS TO THE
GOING FORECAST. A BACKDOOR COLD FRONT WAS PUSHING W THROUGH THE
FORECAST AREA THIS MORNING. THE FRONT APPEARED TO BE BETWEEN KBIL
AND KMLS AT 14Z. THE FRONT WILL PUSH THROUGH THE ENTIRE AREA BY
EARLY AFTERNOON TURNING ALL THE WINDS TO AN EASTERLY DIRECTION.
MADE SOME SMALL WIND ADJUSTMENTS BASED ON NEW WRF AND RAP MODELS.
THE LOW-LEVEL E FLOW WILL LIMIT MIXING TO AROUND 850 MB E OF KBIL
AND TO NEAR 700 MB IN THE W. WITH THE BETTER MIXING OVER THE
W...HAVE RAISED THE HIGH TEMPERATURES A FEW DEGREES. SOME HIGH
CLOUD COVER WAS SEEN ON SATELLITE IMAGERY OVER NE MT THIS MORNING
ASSOCIATED WITH A JET. OTHER CLOUDS WERE ENCROACHING ON SW MT
AHEAD OF THE UPPER LOW ALONG THE PACIFIC NW COAST. RAISED CLOUD
COVER SLIGHTLY OVER THE FAR EASTERN AND WESTERN ZONES BASED ON THE
ABOVE. ARTHUR
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
UPPER RIDGE OF HIGH PRESSURE WILL BE OVER THE NORTHERN PLAINS
EARLY IN THE PERIOD BUT WILL BE SLOWLY WORN DOWN BY A SERIES OF
DISTURBANCES MOVING IN FROM THE EASTERN PACIFIC. MODELS ARE IN
GOOD AGREEMENT IN BRINGING A CLOSED UPPER LOW PRESSURE SYSTEM
ACROSS OREGON AND INTO NORTHERN NEVADA ON MONDAY. THIS LOW WILL
WEAKEN AND BECOME AN OPEN WAVE AS IT SINKS SLOWLY SOUTHWARD INTO
NORTHERN COLORADO MONDAY. MODELS STILL INDICATING SOME WEAK ENERGY
FROM THIS SYSTEM WILL CLIP OUR MOUNTAINS AND WILL CONTINUE CHANCE
POPS FOR THESE AREAS. ANOTHER PIECE OF ENERGY WILL MOVE OUT OF
BRITISH COLUMBIA ON WEDNESDAY AND MODELS ARE DEPICTING A CLOSED
UPPER LOW TO FORM OVER NORTHWEST MONTANA. MODELS ARE NOT LINING UP
WELL ON THE TRACK OF THIS STORM BUT HAVE GONE AHEAD AND INTRODUCED
LOW POPS OVER THE PLAINS FOR WEDNESDAY NIGHT THROUGH THURSDAY.
MODELS ARE BRINGING AMPLE PACIFIC MOISTURE ACROSS THE AREA AND
ADDITIONAL LIFT WILL BE PROVIDED BY A SPEED MAX MOVING ACROSS THE
AREA. UPPER RIDGE BREAKING DOWN FRIDAY AND SATURDAY WITH A DRY AND
FAST ZONAL FLOW SETTING UP ACROSS THE FORECAST AREA.
TEMPERATURES THROUGH THE PERIOD WILL REMAIN SLIGHT ABOVE NORMAL
FOR THIS TIME OF THE YEAR AS NO SIGNIFICANT HEIGHT FALLS ARE
ANTICIPATED. RICHMOND
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL ACROSS THE AREA TODAY AND
TONIGHT...WITH LIGHT EASTERLY WINDS EXPECTED. POOR VISIBILITY WILL
BE POSSIBLE IN KSHR WITH WILDFIRES BURNING EAST OF THE AREA.
CHURCH
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 079 047/078 050/081 054/076 053/077 053/077 053/078
0/U 00/U 00/B 00/U 02/T 20/B 00/U
LVM 081 037/081 043/079 045/078 043/079 043/078 044/078
0/U 00/B 00/B 00/B 02/T 20/B 00/U
HDN 081 042/083 047/085 050/081 049/081 050/081 049/081
0/U 00/U 00/B 00/U 02/T 20/U 00/U
MLS 071 039/075 043/081 048/081 049/081 051/079 050/079
0/U 00/U 00/U 00/U 01/B 22/W 00/U
4BQ 075 039/075 047/084 051/080 050/081 052/078 051/079
0/U 00/U 00/U 00/U 02/T 22/W 00/U
BHK 065 034/072 039/080 045/078 047/078 048/076 048/075
0/U 00/U 00/U 00/U 01/B 22/W 00/U
SHR 076 039/080 044/082 046/076 046/077 045/077 044/077
0/U 00/U 00/B 02/T 22/T 22/W 10/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
621 AM EDT SAT SEP 22 2012
.SYNOPSIS...
RAIN WITH EMBEDDED THUNDERSTORMS WILL LIFT ACROSS THE REGION THROUGH
THIS MORNING. MEANWHILE...A COLD FRONT ASSOCIATED WITH THIS WEATHER
WILL PUSH ACROSS THE REGION AND USHER IN COOLER AIR FOR THE LATTER
HALF OF THE WEEKEND. STEADY RAINS SHOULD END BY THIS AFTERNOON...BUT
EXPECT SOME LAKE EFFECT RAIN SHOWERS TO DEVELOP TONIGHT AND SUNDAY
EAST OF THE LAKES. QUIETER WEATHER AND GRADUALLY MODERATING
TEMPERATURES WILL RETURN FOR NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AN UPPER LEVEL TROF WILL LIFT ACROSS THE LOWER LAKES FROM SOUTHWEST
TO NORTHEAST THIS MORNING. THIS IS CAUSING A LARGE AREA OF
RAIN...WITH SOME EMBEDDED THUNDERSTORMS...TO LIFT ACROSS THE REGION.
THIS WILL BRING A FEW HOURS OF STEADY RAIN NORTH AND WEST OF
ROCHESTER...WITH A SHOWERS LIKELY SOUTH OF THIS. MODEL GUIDANCE IS
IN GOOD AGREEMENT...WITH THE HRRR HAVING A GOOD HANDLE ON THIS LARGE
SCALE FEATURE. FOLLOWING THIS...EXPECT THE STEADY RAINS TO BE OVER
BY MID-MORNING...PERHAPS EVEN EARLIER IN FAR WESTERN SECTIONS.
ONE OTHER CONCERN EARLY THIS MORNING IS A STRONG LOW LEVEL JET WHICH
IS ASSOCIATED WITH THIS TROF. THE 00Z NAM AND SEVERAL RUNS OF THE
RAP SHOW WINDS INCREASING TO 60 KTS AT 2000 FEET EAST OF LAKE
ONTARIO. THIS INCREASE IS VERY SHORT LIVED...AND WINDS DO NOT LINE
UP TERRIBLY WELL. THIS SAID...SUCH STRONG WINDS IS ALWAYS WORTH
WATCHING...WITH A COUPLE HOURS OF WIND GUSTS TO 45 MPH LIKELY IN THE
BLACK RIVER VALLEY EARLY THIS MORNING. ELSEWHERE...WINDS ARE A
LESSER CONCERN...WITH THE LOW LEVEL JET NOT NEARLY AS DEVELOPED
ACROSS WESTERN PORTIONS OF THE CWA.
AFTER THIS FEATURE EXITS BY LATE MORNING...THERE WILL ONLY BE A
BRIEF LULL IN THE ACTION. THEN THE NEXT WAVE OF UPPER LEVEL ENERGY
WILL APPROACH LATE MORNING. WHILE THIS IS FAIRLY POTENT AT 500
MB...IT WILL NOT HAVE THE LOW LEVEL JET SUPPORT THIS FIRST WAVE
DOES...SO EXPECT MORE IN THE WAY OF SHOWERS TO BE ASSOCIATED WITH
IT. ALSO...BEING BEHIND THE COLD FRONT...TEMPERATURES WILL STRUGGLE
TO RISE OR EVEN FALL DURING THE AFTERNOON HOURS. LAKE ENHANCED
CLOUDS AND SHOWERS WILL ALSO DEVELOP IN THE WESTERLY FLOW BEHIND THE
FRONT.
FOR TONIGHT...THE REGION WILL BE IN A BROAD WESTERLY FLOW IN A
CYCLONIC UPPER LEVEL FLOW. 850 MB TEMPERATURES WILL DROP TO NEAR
0C...WHICH WILL SUPPORT SIGNIFICANT INSTABILITY WITH RESPECT TO THE
LAKES. THIS WILL LIKELY BRING LAKE-EFFECT SHOWERS EAST OF EACH LAKE.
INITIALLY...EXPECT THE MOST ACTIVITY TO BE OFF LAKE ERIE IN
ASSOCIATION WITH A SHORTWAVE CROSSING DURING THE EVENING HOURS. THEN
LAKE ONTARIO WILL BECOME MORE ACTIVE LATER IN THE NIGHT...GIVEN THE
LONG WESTERLY FETCH. EVEN AN ISOLATED THUNDERSTORM IS NOT OUT OF THE
QUESTION IN THE MOST DEVELOPED LAKE ENHANCED SHOWERS.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
ON SUNDAY A -2SD 500 HPA BROAD LONG WAVE TROUGH WILL BE SPIRALING
EAST AND NORTHWARD FROM THE CENTRAL GREAT LAKES. A POOL OF COLD AIR
ALOFT ASSOCIATED WITH THIS LONGWAVE TROUGH WILL BE CENTERED OVER THE
EASTERN GREAT LAKES REGION...PROVIDING FOR A COOL FALLISH TYPE
DAY...WITH LAKE EFFECT RAIN.
BOTH THE NAM AND THE REGIONAL CANADIAN MODEL PLACE AN AREA OF UPWARD
MOTION TO THE EAST OF BOTH GREAT LAKES...WITH THE MORE IMPRESSIVE
VERTICAL MOTION TO THE EAST OF LAKE ONTARIO. LAKE TEMPERATURES
AROUND 20C UNDER THE POOL OF COLD AIR OF AROUND 1C AT 850 WILL
CREATE SIGNIFICANT LAKE INDUCED INSTABILITY. LAKE INDUCED EQL OVER
25K FEET WITH LAKE INDUCED CAPE VALUES OF AROUND 1500 J/KG WILL
PROVIDE PLENTY OF INSTABILITY AND WITH HIGH MOISTURE CONTENT AROUND
3-4K FEET EXPECT A PLUME OF LAKE EFFECT RAIN OFF BOTH LAKES. WILL
PLACE HIGHER...CATEGORICAL POPS OFF LAKE ONTARIO WHERE MOISTURE
FIELDS ARE A LITTLE MORE IMPRESSIVE...WHILE MAINTAINING LIKELY OFF
LAKE ERIE.
WINDS THROUGH THE DAY ON SUNDAY WILL BE WEST...WITH A SLIGHT
SOUTHWEST COMPONENT...MAINLY BETWEEN 250-270 DEGREES. THIS WILL PLACE
THE PRIMARY LAKE EFFECT BANDS JUST SOUTH OF BUFFALO...AND ALONG AND
JUST SOUTH OF WATERTOWN. AT TIMES EXPECT THE LAKE ONTARIO BAND OF
LAKE EFFECT RAIN TO BRUSH BY THE AREAS JUST SOUTH OF THE SOUTHERN
SHORELINE OF LAKE ONTARIO. GREATEST RAINFALL WILL BE EAST OF LAKE
ONTARIO WHERE THE LONG FETCH OVER LAKE ONTARIO WILL DRIVE MODERATE
RAIN SHOWERS ACROSS THE EASTERN LAKE ONTARIO REGION...WITH RAINFALL
ENHANCED IN THE UPSLOPE AREAS OF THE WESTERN FACE OF THE TUG HILL
REGION. HOW MUCH RAINFALL IS STILL UNCERTAIN AT THIS TIME BUT WILL
HAVE AN AVERAGE BASIN QUARTER TO HALF INCH OF RAINFALL IN MOST
PERSISTENT RAIN BANDS IN THE GRIDS EAST OF LAKE ONTARIO. WITH A
SHORTER FETCH EAST OF LAKE ERIE...RAINFALL TOTALS WILL LIKELY BE A
LITTLE LESS THROUGH THE DAY ON SUNDAY.
THOUGH THE MAIN UPPER LEVEL TROUGH WILL BE ADVANCING ACROSS SOUTHERN
CANADA SUNDAY NIGHT...ANOTHER SHORTWAVE DIVING SOUTHWARD THROUGH THE
CENTRAL GREAT LAKES WILL CARVE A TROUGH ACROSS THE EASTERN GREAT
LAKES LATER IN THE NIGHT. EXPECT SFC WINDS TO VEER TO MORE
NORTHWESTERLY BEHIND THIS TROUGH WITH THE LAKE EFFECT RAIN BANDS
SHIFTING SOUTH AND EAST OF THE LAKES. AGAIN WITH THE LONGER FETCH
AND DEEPER MOISTURE OFF LAKE ONTARIO WILL CONTINUE WITH HIGHER POPS
HERE.
MOISTURE DEPTH FOR SUNDAY WILL TOUCH THE -10C LEVEL WHERE GRAUPEL IS
LIKELY. WITH THE SUCH COLD TEMPERATURES ALOFT AND MODERATE
INSTABILITY WILL ADD ISOLATED THUNDER INTO THE GRIDS FOR THE LAKE
EFFECT RAIN BANDS SUNDAY AND SUNDAY NIGHT.
OUTSIDE THESE LAKE EFFECT RAIN BANDS EXPECT PARTLY TO MOSTLY SUNNY
SKIES. HOWEVER THIS SUNSHINE WILL BE SELF DESTRUCTIVE...WITH THE
COLD POOL OVERHEAD DAYTIME HEATING WILL CREATE POCKETS OF
INSTABILITY SHOWERS. THESE WILL LIKELY BE SCATTERED AND BRIEF...AND
WILL PLACE JUST A LOW CHC INTO THE GRIDS.
EVEN WITH THE SUNSHINE COOL TEMPERATURES WILL REMAIN WITH
HIGHS OUTSIDE OF THE LAKE EFFECT RAIN BANDS IN THE UPPER 50S TO
LOWER 60S. WITHIN THE BANDS OF RAIN AND THICKER CLOUDS HIGHS ON
SUNDAY WILL LINGER IN THE MID 50S. TEMPERATURES SUNDAY NIGHT WILL
FALL BACK INTO THE 40S...TO UPPER 30S. THERE MAY BE PATCHY FROST
ACROSS THE TRADITIONALLY COLDER AREAS OF THE INLAND SOUTHERN TIER
SUNDAY NIGHT.
MONDAY WINDS AT THE SFC WILL VEER BACK TO SOUTHWEST. DRIER AIR WILL
BEGIN TO FUNNEL ACROSS THE CWA BEHIND AN UPPER LEVEL TROUGH AXIS.
LAKE EFFECT RAIN WILL DIMINISH THROUGH THE DAY...FIRST OFF LAKE ERIE
AND THEN LAKE ONTARIO...WHILE THEY SLOWLY PUSH NORTHWARD. WITH
HEIGHTS ALOFT INCREASING THROUGH THE DAY AND SLOW WARM AIR ADVECTION
THE BULK OF THE REGION OUTSIDE THE LAKE EFFECT RAIN WILL BE DRY WITH
INCREASING AMOUNTS OF SUNSHINE. STILL ON THE COOL SIDE MONDAY THOUGH
DAYTIME HIGHS SHOULD PUSH A DEGREE OR SO WARMER THAN SUNDAYS HIGHS.
WITH THE CLEARING SKIES MONDAY NIGHT ANOTHER CHILLY NIGHT WITH LOWS
AGAIN MAINLY IN THE 40S. THESE READINGS WILL BE ABOUT 5 DEGREES
COOLER THAN NORMAL. HIGH PRESSURE AT THE SURFACE WILL BE ELONGATED
THROUGH THE MID ATLANTIC STATES AND TOWARDS NEW ENGLAND WITH LIGHT
WINDS. WITH THE CLEAR SKIES AND LIGHT WINDS PATCHY FROST ACROSS THE
INTERIOR SOUTHERN TIER AND NORTH COUNTRY MAY BE OF CONCERN.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
TUESDAY...HIGH PRESSURE WILL SHIFT FROM THE OHIO VALLEY TO THE MID
ATLANTIC WITH A SOUTHWEST FLOW ACROSS THE GREAT LAKES AND NEW YORK.
A LOW PRESSURE WILL BE RIDING NORTHEASTWARD ALONG A BAROCLINIC
ZONE...BUT WITH THE UPPER LEVEL TROUGH STILL HANGING BACK ACROSS THE
WESTERN GREAT LAKES...ANY SHOWERS WITH THIS FEATURE SHOULD STAY TO
JUST TO OUR WEST. WITH THE SOUTHERLY FLOW WE SHOULD WARM
TEMPERATURES BACK TO NEAR NORMAL AFTER AN UNSETTLED SHORT TERM.
ON WEDNESDAY BOTH THE 00Z RUNS OF THE GFS AND THE ECMWF SWING AN
UPPER LEVEL SHORT WAVE ACROSS THE REGION...WHICH WILL FORCE THE
BAROCLINIC ZONE/COLD FRONT ACROSS THE REGION. WILL HAVE CHC FOR
SHOWERS BOTH WEDNESDAY AND WEDNESDAY NIGHT WITH THE GREATEST THREAT
ACROSS THE NORTHERN FINGER LAKES AND EASTERN LAKE ONTARIO
REGION...WHICH WILL BE CLOSER TO THE INFLUENCE OF THE UPPER
SHORTWAVE AND HEIGHT FALLS.
FOR THURSDAY THE UPPER LEVEL TROUGH WILL BE JUST TO OUR EAST WITH
NORTHERLY WINDS BEHIND THE COLD FRONT AT THE SFC. SOME MORNING
CLOUDS MAY LINGER JUST SOUTH OF LAKE ONTARIO...OTHERWISE EXPECT
INCREASING AMOUNTS OF SUNSHINE ON THURSDAY AS CANADIAN HIGH PRESSURE
SHIFTS FROM THE NORTHERN PLAINS EAST TO THE GREAT LAKES. THIS SHOULD
BRING DRY WEATHER BACK FOR THURSDAY AND FRIDAY.
TEMPERATURES ON THURSDAY BEHIND THE COLD FRONT WILL FALL BACK A FEW
DEGREES FROM WEDNESDAYS HIGHS...AND THEN REBOUND BACK TO NEAR NORMAL
FOR FRIDAY.
&&
.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
BETWEEN 09Z AND 15Z...A TROF IN THE MID AND UPPER LEVELS WILL
QUICKLY SWEEP ACROSS THE LOWER LAKES FROM SW TO NE. ASSOCIATED
WITH THIS IS A VIGOROUS LOW LEVEL JET...WHICH WILL RESULT IN WIND
SHEAR IN ALL TAF LOCATIONS TO THE SE OF THE TRACK OF THE
DISTURBANCE (ALL BUT IAG/BUF). THIS WILL ALSO BRING A PERIOD OF RAIN
ACROSS AND NEAR THE LAKES...WITH MORE SHOWERY ACTIVITY TO THE
SOUTH AND EAST OF THIS WHERE PRECIPITATION WILL BE ASSOCIATED WITH
THE PASSAGE OF A FRONTAL BOUNDARY. MODERATE RAIN SHOULD LOWER VSBY
TO AROUND 3SM...WITH LOWEST CONDITIONS LIKELY TO COME NEAR AND
JUST AFTER THE FRONTAL PASSAGE...WHEN CIGS SHOULD LOWER TO MVFR OR
LOWER.
FROM 15Z TO 00Z SUN...EXPECT A MIX OF VFR AND MVFR CONDITIONS. BY
THIS TIME...THE STEADY RAIN SHOWERS WILL HAVE EXITED TO THE
EAST...WITH LINGERING MVFR CIGS AND GUSTY WINDS THE MAIN THINGS TO
WATCH. WINDS SHOULD DIMINISH...AND CIGS SHOULD IMPROVE TOWARD
00Z...THOUGH A FEW LAKE ENHANCED SHOWERS CAN NOT BE RULED OUT EAST
OF THE LAKES.
FOR TONIGHT...EXPECT PRIMARILY VFR CONDITIONS...WITH AREAS OF MVFR
CIGS/SHOWERS DUE TO LAKE EFFECT RAIN SHOWERS. THE BEST CHANCE FOR
THIS WILL BE AT JHW...GIVEN THE WESTERLY FLOW.
OUTLOOK...
SUNDAY...VFR/MVFR WITH SCATTERED TO NUMEROUS SHOWERS...ESPECIALLY
EAST OF THE LAKES.
MONDAY THROUGH WEDNESDAY...MAINLY VFR.
&&
.MARINE...
A STRONG COLD FRONT WILL CROSS THE LOWER LAKES THIS MORNING AND
EARLY AFTERNOON. THE BIG CONCERN FOR THE WATERS IS THAT A BRIEF
PERIOD OF GUSTY WINDS IS LIKELY TO PROCEED THE FRONT. THIS WILL
BRING AN HOUR OR TWO OF 30 KNOT SUSTAINED WINDS...WITH GUSTS TO 40
KTS ON THE EASTERN HALF OF LAKE ONTARIO. WINDS WILL THEN SHIFT TO
THE WEST AND INITIALLY DIMINISH BEHIND THE FRONT. THEN WINDS WILL
BECOME WESTERLY...GENERALLY IN THE 15 TO 25 KNOT RANGE ACROSS MUCH OF
THE LOWER LAKES REGION DURING SATURDAY...THEN REMAINING RELATIVELY
BRISK THROUGH SUNDAY. AS A RESULT...SMALL CRAFT ADVISORIES ARE IN
PLACE FOR MOST OF THE WATERS.
IN ADDITION...WITH MUCH COOLER AIR FLOODING ACROSS THE
LAKES...WATERSPOUTS MAY ALSO BECOME A CONCERN TONIGHT AND ESPECIALLY
SUNDAY. THE BEST CHANCE FOR THESE WILL BE ASSOCIATED WITH CONVERGENT
FLOW ALONG LAKE ENHANCED SHOWERS.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT SUNDAY FOR
LEZ040-041.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 7 PM EDT THIS
EVENING FOR LEZ020.
SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT
SUNDAY FOR LOZ042>044.
SMALL CRAFT ADVISORY UNTIL 6 PM EDT SUNDAY FOR LOZ045.
SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON
FOR SLZ022-024.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1025 AM EDT SAT SEP 22 2012
.SYNOPSIS...
A WARM FRONTAL BOUNDARY OVER NORTHERN PENNSYLVANIA WILL BRING A FEW
SHOWERS TO THAT REGION EARLY TODAY. A POTENT UPPER LEVEL DISTURBANCE
AND STRONG COLD FRONT CROSSING OHIO WILL PUSH EAST THROUGH CENTRAL
PENNSYLVANIA AND THE SUSQUEHANNA VALLEY DURING THE MIDDAY AND
AFTERNOON HOURS...ACCOMPANIED BY SCATTERED SHOWERS AND
THUNDERSTORMS. FOLLOWING THE FRONT...MUCH COOLER AND DRIER AIR WILL
OVERSPREAD THE STATE FOR SATURDAY NIGHT AND SUNDAY. A LARGE AREA OF
HIGH PRESSURE WILL BUILD INTO THE COMMONWEALTH FOR THE FIRST HALF OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SFC COLD FRONT EXTENDS FROM KPIT-KDUJ TO KELM AND KSYR AT THIS
TIME. PREFRONTAL SHOWER BANDS LIFTED NORTH OF THE NY/PA BORDER
DURING THE MID MORNING HOURS AND MUCH OF CENTRAL AND SOUTHEAST
PORTIONS OF MY FORECAST AREA ARE SEEING SOME NICE SUNSHINE. WEST
OF THE ALLEGHENY FRONT...WHERE BOUNDARY LAYER FLOW IS NEARLY
PARALLEL TO THE BAROCLINICITY AND UPSLOPE FLOW IS AIDING CLOUD
ENHANCEMENT...WEAK BANDS OF LIGHT SHOWERS EXTEND ALONG THE FRONTAL
ZONE. HIGH RESOLUTION MODELS SUGGEST THESE WILL HAVE A DIFFICULT
TIME NAVIGATING THE DOWNSLOPE ACROSS SOUTHERN PORTIONS OF THE
EASTERN HALF OF MY CWA. EXPECT SHOWERS TO BE MOST NUMEROUS FROM
THE WEST CENTRAL MOUNTAINS NORTHWARD (NORTH OF I80) WITH THIS
ACTIVITY.
AS PREVIOUSLY MENTIONED...TAIL END OF MODERATELY STRONG 850 MB
MOISTURE FLUX SLIDES ACROSS CENTRAL PENN DURING THE MIDDAY AND
EARLY AFTERNOON HOURS... ACCOMPANIED BY ONE OR TWO NARROWING BANDS
OF LIGHT TO MDT RAIN SHOWERS. MESOSCALE MODELS CONTINUE TO SUGGEST
THAT MOST RAINFALL SKIRTS THE LAURELS AND THE CENTRAL
MTNS PRIOR TO REFORMING AS A BKN LINE OF HEAVIER SHOWERS/SCATTERED
TSRA DURING THE EARLY TO MID AFTERNOON HOURS. LATEST HRRR ACTUALLY
FORMS THE LINE EAST OF MY CWA LATE THIS AFTERNOON...WITH ONLY
ISOLATED TO SCATTERED SHOWER ACTIVITY OVER MY CWA.
IT WILL BE ANOTHER MILD DAY OVER MUCH OF THE EASTERN PART OF THE
FCST AREA...WITH CHILLIER AIR SPILLING IN BEHIND THE FRONT KEEPING
THE NW MOUNTAINS IN THE 60S. ELSEWHERE THE 70S LOOK LIKE A DECENT
BET...WITH U70S TO L80S EXPECTED FOR THE LOWER SUSQ VALLEY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
COOL
POST-FRONTAL WEATHER REGIME WILL SPREAD ACROSS THE COMMONWEALTH
TONIGHT THROUGH SUNDAY...AS A SPRAWLING UPPER LOW EXTENDING FROM THE
NORTHERN GREAT LAKES TO HUDSON BAY LIFTS SLOWLY NORTHEASTWARD.
SUNDAY WILL FEATURE AFTERNOON TEMPERATURES BETWEEN 7 AND 10 DEG F
BELOW NORMAL AS THE MEAN UPPER TROF PERSISTS OVER EASTERN CANADA
KEEPING CHILLY AIR OVER THE GREAT LAKES AND NORTHEAST. HIGHS WILL
VARY FROM THE LOWER TO MID 50S ACROSS THE NW MTNS AND LAURELS...TO
THE MID 60S THROUGHOUT MUCH OF THE SUSQ VALLEY.
IT WILL BE CLOUDY FOR MUCH OF WESTERN AND NORTHERN PA...WITH A CHC
OF SHOWERS EXTENDING INTO THE CENTRAL MOUNTAINS.
CLOUDS SHOULD DISSIPATE IN MOST LOCATIONS...AND RETREAT TO COVER
MAINLY THE WESTERN MTNS SUNDAY NIGHT...WHICH WILL SET THE STAGE FOR
A VERY COOL...AND LIKELY FROSTY NIGHT ACROSS THE NORTH. WILL NOTE
THE POTENTIAL OF SCATTERED FROST IN THE HWOCTP ACROSS THE NRN MTNS
AND LAURELS /SHOULD CLOUD AND WIND DISSIPATE ENOUGH/.
LOWS AROUND DAYBREAK MONDAY WILL RANGE FROM THE MID 30S ACROSS THE
NRN MTNS TO THE UPPER 30S AND MID 40S ELSEWHERE.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
LATEST MODEL AND ENSEMBLE GUIDANCE CONTINUES TO SHOW ANOTHER FAIRLY
VIGOROUS UPPER TROF CROSSING THE REGION SUNDAY NIGHT AND MONDAY...
BRINGING CONTINUED COOL TEMPS AND ANOTHER PERIOD OF SCATTERED
SHOWERS.
A ZONAL FLOW DEVELOPS LATER MONDAY AND TUESDAY WITH MODERATING 850
MB TEMPERATURES AND HIGH PRESSURE BUILDS ENE FROM THE CENTRAL
TENNESSEE RIVER VALLEY. TEMPS WILL MODERATE FURTHER ON WEDNESDAY
AHEAD OF A FRONTAL SYSTEM DROPPING SOUTHWARD FROM THE GREAT LAKES.
THE FRONT SHOULD SAG AND STALL SOUTH OF THE MASON DIXON LINE LATE
THIS WEEK...WITH COOLER AN DRIER WEATHER TO THE NORTH.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
ISOLATED SHOWERS CONTINUE ALONG A WEAK BOUNDARY MOVING THROUGH CENTRAL
PA THIS MORNING. THE MAIN LINE CONTINUES TO DECREASE IN INTENSITY
AS IT MOVES TO THE NORTHEAST. A RELATIVELY STRONG CFRONT CONTINUES
TO APPROACH FROM THE WEST.
BEHIND THE BAND...BFD HAS IFR VSBYS...AND WILL CONTINUE TO BE SO
THROUGH 16Z.
EXPECT MOST AREAS TO BE VFR...WITH PERIODS OF MVFR CIGS AND VSBYS
IN SHOWERS AND POSSIBLY TSRA THIS AFTERNOON AND EVENING. STRONG
TO SEVERE STORMS EAST OF THE MOUNTAINS REMAINS A POSSIBILITY DUE
TO FRONTAL PROGRESSION AND THE PRESENCE OF SHEAR AND SOUTHEASTERLY FLOW.
THE DRY SLOT WORKS IN LATE TODAY INTO EARLY TOMORROW. COLD AIR
ALOFT WILL LIKELY TRIGGER SOME SHOWERS LATE SUNDAY... PERHAPS
INTO MONDAY MORNING.
AS THE HIGH MOVES EAST AND SOUTH OF THE AREA LATE MONDAY
INTO TUE. A WARMER SW FLOW OF AIR WILL SET IN FOR MID WEEK.
OUTLOOK...
SUN...MAINLY VFR BUT MVFR CONDITIONS POSSIBLE ACROSS THE HIGHER
MTNS WITH A FEW SHOWERS.
MON...BECOMING VFR...AS HIGH PRESSURE BUILDS ACROSS THE AREA.
TUE-WED...VFR...WITH A FEW SHOWERS POSS LATER TUES INTO WED
ACROSS WESTERN MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...DEVOIR/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...LAMBERT
AVIATION...CERU/MARTIN
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
940 AM MST SAT SEP 22 2012
.SYNOPSIS...
HIGH PRESSURE IN THE UPPER ATMOSPHERE WILL RESULT IN WELL ABOVE
NORMAL TEMPERATURES THROUGH THIS WEEKEND. A COOLING TREND IS
EXPECTED STARTING MONDAY AS AN AREA OF LOW PRESSURE MOVES THROUGH
THE SOUTHERN ROCKIES. THERE IS ALSO A SLIGHT CHANCE OF SHOWERS
MONDAY...THOUGH MUCH OF THE AREA WILL NOT SEE RAINFALL. BELOW
AVERAGE TEMPERATURES ARE EXPECTED FROM TUESDAY THROUGH AT LEAST THE
WEEKEND.
&&
.DISCUSSION...
AS/AC CLOUD DECK WHICH HAS BEEN A REOCCURRING FEATURE THE PAST
SEVERAL MORNINGS WAS BEGINNING TO THIN SOMEWHAT...THOUGH WEAK ASCENT
ASSOCIATED WITH A MID TROPOSPHERIC FRONT (EVIDENT BY MORE EXTENSIVE
VIRGA) MAY KEEP CLOUDS MORE PREVALENT THIS AFTERNOON.
REGARDLESS...12Z SOUNDING DATA DEPICTING H8 TEMPS AT +25C PORTENDS
ANOTHER VERY WARM DAY DESPITE THE CLOUD COVER...WITH AFTERNOON HIGHS
LIKELY TOPPING OUT VERY NEAR A PERSISTENCE FORECAST. OTHER THAN
MINOR ADJUSTMENTS TO HOURLY TEMPERATURE TRENDS AND SKY COVER...THE
FORECAST NEEDED NO OTHER ALTERATIONS THIS MORNING.
&&
.PREVIOUS DISCUSSION...
LATEST RAP ANALYSIS SHOWS THE ANTICYCLONE REORGANIZING ACROSS NM
EARLY THIS MORNING. THIS HAS RESULTED IN A VEERING FLOW AND AN
INCREASE IN SOUTHERLY WINDS IN THE MID-LEVELS ACROSS SOUTH-CENTRAL
AZ. MEANWHILE...LATEST TUCSON 00Z SOUNDING CONTINUES TO PICK UP ON
THE MOISTURE SITTING JUST BELOW A PERSISTENT SUBSIDENCE INVERSION
AROUND 500 MB. GIVEN THE STEERING FLOW...ALTOSTRATUS WILL LIKELY
MAKE ANOTHER APPEARANCE THIS MORNING. INCREASE IN MID CLOUDS AND
CIRRUS IN SOUTHERN CA AHEAD OF THE PACIFIC TROUGH WILL INHIBIT SOLAR
INSOLATION EVER SO SLIGHTLY AND MAX TEMPS FOR THIS AFTERNOON WERE
LOWERED ABOUT A DEGREE. NEVERTHELESS...MAX TEMPS WILL REMAIN WELL
ABOVE AVERAGE AND AROUND 105 DEGREES IN PHOENIX. LITTLE CHANGE IN
TEMPERATURES IS EXPECTED SUNDAY AS THE VORT MAX CURRENTLY OFF THE WA
COAST DROPS TO THE SOUTHEAST AND INTO THE GREAT BASIN.
MODELS REMAIN SOMEWHAT OUT OF PHASE WITH REGARD TO THE EVOLUTION OF
THE GREAT BASIN LOW PRESSURE SYSTEM EARLY NEXT WEEK...THOUGH
STRONGER WEIGHT WAS ASSIGNED TO THE NAM AND ECMWF WHICH HAVE
EXHIBITED A TREND TOWARDS LOWER HEIGHTS FURTHER SOUTH.
CONSEQUENTLY...POPS WERE INCREASED SLIGHTLY AND TOP OUT AT AROUND 20
PERCENT ACROSS EASTERN GILA COUNTY MONDAY AFTERNOON. LOWER LEVELS
WILL GENERALLY REMAIN TOO DRY FOR MEASURABLE PRECIPITATION IN THE
LOWER DESERTS. IN TERMS OF SENSIBLE WEATHER...MAIN IMPACT FROM THIS
SYSTEM WILL BE A DROP IN TEMPERATURES MONDAY INITIALLY...AND THEN
BEHIND THE TROUGH AXIS TUESDAY AND WEDNESDAY.
DETERMINISTIC MODELS SUGGEST SEVERAL MID-LATITUDE AND SUB-TROPICAL
VORTICES WILL CONSOLIDATE INTO A CUTOFF LOW IN THE VICINITY OF THE
BAJA PENINSULA LATE NEXT WEEK. TAKING THE GUIDANCE AT FACE VALUE
WOULD MEAN AN INCREASE IN MOISTURE FRIDAY-SATURDAY ACROSS MEXICO.
HOWEVER...ECWMF/GFS/CMC ENSEMBLES ARE ALL SHOWING A CONSIDERABLE
SPREAD AND THIS IS TO BE EXPECTED...GIVEN THAT CUTOFFS IN THIS
REGION ARE NOTORIOUSLY DIFFICULT TO FORECAST...PARTICULARLY IN THE
EXTENDED RANGE. MOST LIKELY SCENARIO IS THAT THE DRIER CLIMATOLOGY
WILL WIN OUT AND POPS WERE LOWERED BELOW 10 PERCENT.
&&
.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...AND KSDL...
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH...
MOSTLY SUNNY SKIES WITH SCT-BKN MID-HIGH LEVEL CLOUDS OVER THE
REGION DURING THE PERIOD. EXPECT LIGHT WINDS LESS THAN 10KT AT ALL
TAF SITES THROUGH AT LEAST 09Z SUNDAY MORNING.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
WARMER THAN AVERAGE TEMPERATURES EARLY IN THE WEEK WILL ABRUPTLY
COOL TOWARDS SEASONAL NORMALS AS A WEAK LOW PRESSURE SYSTEM MOVES
THROUGH THE GREAT BASIN MONDAY AND TUESDAY. WITH THE PASSAGE OF THIS
LOW PRESSURE SYSTEM...SOUTHWEST WINDS WILL INCREASE AND BECOME GUSTY
UP TO 25 MPH ACROSS SOUTHEAST CALIFORNIA AS WELL AS THE HIGHER
ELEVATIONS OF SOUTH-CENTRAL ARIZONA MONDAY AFTERNOON. WIND SPEEDS
WILL TAPER OFF AND FOLLOW MORE TYPICAL DIRECTIONAL TRENDS TUESDAY
THROUGH FRIDAY. DAYTIME HUMIDITY LEVELS WILL GRADUALLY TREND UP FROM
THE TEENS TO BACK ABOVE 20 PERCENT ACROSS THE LOWER DESERTS BY THE
END OF THE WEEK...ACCOMPANIED BY GOOD RECOVERY EACH NIGHT.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX
DISCUSSION...HIRSCH/MO
AVIATION...MEYERS
FIRE WEATHER...MO
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
130 PM PDT SAT SEP 22 2012
.SYNOPSIS...
HIGH PRESSURE ALOFT OVER THE WEST WILL CONTINUE TO BRING ABOVE
AVERAGE TEMPERATURES TO THE REGION THROUGH SUNDAY. BY MONDAY A
TROUGH OF LOW PRESSURE WILL DEEPEN OVER THE WESTERN STATES AND BRING
MORE PERSISTENT LOW CLOUDS...AS WELL AS GUSTY WEST WINDS TO THE
MOUNTAINS AND DESERTS AT TIMES. A WARMING TREND SHOULD BEGIN BY
MIDWEEK AND CONTINUE THROUGH FRIDAY.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH MONDAY)...
THE HRRR MODEL IS NOW CLEARING THE LOW CLOUDS OUT OF THE COASTAL
WATERS...AND BRINGS IN THE LOW CLOUDS AGAIN AT AROUND 03Z THIS
EVENING. IT IS FORECASTING SOME PATCHY FOG THIS EVENING. WE DO
EXPECT THE LOW CLOUDS TO SHOW ONLY SUBTLE CHANGES IN THE PATTERN
THROUGH SUNDAY MORNING.
FOR TONIGHT...THE WRF-EMS MODEL ALSO PAINTS A PICTURE SIMILAR TO
THIS MORNING. STILL THE MOS GUIDANCE SEEMS TO SUPPORT A BIT OF
WARMING FOR SUNDAY.
FOR MONDAY...PLAN ON AN EARLY SEASON TROUGH OF LOW PRESSURE IN THE
PACIFIC NORTHWEST MOVING INTO THE GREAT BASIN. THIS WILL BRING
STRONGER ONSHORE FLOW...DEEPENING OF THE MARINE LAYER...AND GUSTY
WEST WINDS IN THE MOUNTAINS AND DESERTS. A COOLING TREND IS ALSO IN
THE CARDS.
&&
.LONG TERM (TUESDAY THROUGH FRIDAY)...
AN ENSEMBLE OF MODELS TRY TO PLACE WEAK LOW PRESSURE OVER THE WEST
COAST...WITH CONTINUING DIFFERENCES IN THE GLOBAL MODELS.
TEMPERATURES WILL BE DOWN TO AROUND SEASONAL AVERAGES BY TUESDAY
WITH AREAS OF LATE NIGHT AND EARLY MORNING COASTAL LOW CLOUDS AND
FOG. THERE IS LIKELY TO BE A WARMING TREND BEGINNING WEDNESDAY. IT
COULD GET QUITE WARM BY FRIDAY PER THE GFS...WITH LESS HEATING NOTED
ON THE ECMWF.
NEXT WEEKEND...THERE IS SOME POTENTIAL FOR TROPICAL MOISTURE...BUT
NOT CERTAIN ENOUGH TO JUMP ON SIGNIFICANTLY IN THE FORECASTS AT THIS
TIME.
&&
.AVIATION...
222030Z...COASTAL AREAS...A FEW LOW CLOUDS WITH LOCAL VIS BLO 1SM
NEAR IMPERIAL BEACH IN EXTREME SW SAN DIEGO COUNTY.
OTHERWISE...SCT-BKN CLOUDS LAYERED FROM 7000 FT TO 20000 FT. STRATUS
AND FOG WILL LIKELY BE PATCHY TONIGHT AS THEY RETURN TO THE COASTAL
AREAS AND MIGHT NOT AFFECT ANY INDIVIDUAL AIRPORT FOR MORE THAN 2-3
HOURS AFTER 06Z SUN. EXPECT CLEARING OF THE LOW CLOUDS AND FOG
AROUND 16Z SUN.
INLAND VALLEYS/MTNS/DESERTS...SCT-BKN CLOUDS LAYERED FROM 7000 FT TO
20000 FT THROUGH SUN.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...SMALL
AVIATION/MARINE...PG
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 AM PDT SAT SEP 22 2012
.SYNOPSIS...
A RIDGE OF HIGH PRESSURE OVER THE WEST WILL RESULT IN ABOVE AVERAGE
TEMPERATURES THROUGH SUNDAY. BY MONDAY A TROUGH OF LOW PRESSURE WILL
BRING MORE PERSISTENT LOW CLOUDS...WITH GUSTY WEST WINDS IN THE
MOUNTAINS AND DESERTS AT TIMES. THE AUTUMNAL EQUINOX WAS AT 0749 AM
PDT THIS MORNING.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (TODAY THROUGH MONDAY)...
HAD SOME DENSE FOG INVADE THE AREA THIS MORNING FOR ADVISORY LEVEL
CONDITIONS...SO ISSUED A DENSE FOG ADVISORY TO COVER IT FOR THIS
MORNING. THIS SHOULD DISSIPATE BY LATE MORNING. THE HRRR MODEL LOOKS
FAIRLY DECENT WITH THE WAY IT IS HANDLING THE MARINE LAYER THIS
MORNING...AND THE MODEL IS FORECASTING THE LOW CLOUDS TO RETREAT
BACK TO THE BEACHES MIDDAY. WITH GRADIENTS THAT ARE
UNIMPRESSIVE...ALONG WITH LITTLE TREND AT THE MOMENT...AND A
MODERATE STRENGTH INVERSION...IT WILL LIKELY CLEAR OF LOW CLOUDS
VIRTUALLY ALL AREAS TODAY. THERE IS A LIKELYHOOD OF A SIGNIFICANT
AMOUNT OF HIGH AND MID CLOUDS AT TIMES OVER THE REGION. THERE SHOULD
BE ENOUGH TO SURPRESS TEMPERATURES SOMEWHAT OVER THE REGION.
FOR TONIGHT...THE WRF-EMS MODEL MAY BE TRENDING TOWARD A LITTLE LESS
OF A MARINE INTRUSION TONIGHT...WHICH WOULD SUPPORT LESS LOW CLOUDS
AND SOMWHAT WARMER TOMORROW. MOS GUIDANCE ALSO SEEMS TO SUPPORT A
BIT OF WARMING FOR SUNDAY.
FOR MONDAY...AN EARLY SEASON TROUGH OF LOW PRESSURE IN THE PACIFIC
NORTHWEST WILL MOVE INTO THE GREAT BASIN. THIS WILL BRING STRONGER
ONSHORE FLOW WITH COOLING...DEEPENING OF THE MARINE LAYER...AND
GUSTY WEST WINDS IN THE MOUNTAINS AND DESERTS. A COOLING TREND WILL
SET IN AS WELL.
&&
.LONG TERM (TUESDAY THROUGH FRIDAY)...
AN ENSEMBLE OF MODELS TRY TO PLACE WEAK LOW PRESSURE OVER THE WEST
COAST...WITH CONTINUING DIFFERENCES IN THE DETAILS AMONG THE GLOBAL
MODELS. TEMPERATURES SHOULD HAVE LOWERED TO NEAR SEASONAL AVERAGES
BY TUESDAY WITH AREAS OF LATE NIGHT AND EARLY MORNING COASTAL LOW
CLOUDS AND FOG. THERE IS LIKELY TO BE A WARMING TREND BEGINNING
WEDNESDAY.
NEXT WEEKEND...THERE IS SOME POTENTIAL FOR TROPICAL MOISTURE TO BE
DRAWN NORTHWARD INTO THE AREA BY LOW PRESSURE OFF THE CALIFORNIA
COAST...BUT A LOT OF UNCERTAINTY INDICATED BY AN ENSEMBLE OF
MODEL SOLUTIONS.
&&
.AVIATION...
221500Z...PATCHY STRATUS/FOG ALONG THE IMMEDIATE COAST THIS
MORNING...CURRENTLY AFFECTING KSAN AND KCRQ. STRATUS AND FOG MAY
BRIEFLY AFFECT KSNA BEFORE 16Z. AREAS OF VIS BELOW 1SM WITH OVC CIGS
AROUND 500 FEET MSL AND TOPS AROUND 900 FT MSL...GRADUALLY
DISSIPATING BY 16Z. STRATUS AND FOG WILL LIKELY BE RATHER PATCHY
TONIGHT AND MIGHT NOT BE AT ANY INDIVIDUAL AIRPORT FOR MORE THAN 2-3
HOURS AFTER 06Z SUN.
OTHERWISE...MOSTLY BROKEN CLOUDS ABOVE 10000 FEET THROUGH SUN.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...SMALL
AVIATION/MARINE...PG
AREA FORECAST DISCUSSION
NWS MIAMI FL
234 PM EDT SAT SEP 22 2012
...FLOODING REMAINS THE MAIN CONCERN THROUGH THE EVENING HOURS...
.SHORT TERM (TONIGHT-MONDAY NIGHT)...
AFTER A BUSY START TO THE DAY THIS MORNING DUE TO FLOODING ALONG
THE EAST COAST FROM MIAMI-DADE TO PALM BEACH...THE LATEST HRRR MODEL
REFLECTIVITIES HAVE INITIALIZED WELL WITH THE CURRENT PATTERN AND
CONTINUE TO INDICATE ANOTHER ROUND OF ACTIVITY REDEVELOPING THROUGH
THE MID TO LATE AFTERNOON AND EVENING PERIODS. FOR COVERAGE...IT IS
INDICATING THE BULK OF THE HEAVIEST ACTIVITY SETTING UP OVER THE
SOUTHERN HALF OF THE LOCAL AREA WITH ANOTHER 1-2 INCHES OF RAINFALL
POSSIBLE IN THE HEAVIEST ACTIVITY. THIS SEEMS REASONABLE AS THE
LATEST VISIBLE SATELLITE IMAGERY SHOWS THE LARGEST BREAKS IN CLOUD
COVERAGE OVER THESE SOUTHERN AREAS WHERE TEMPERATURES HAVE QUICKLY
INCREASED OVER THE PAST 1-2 HRS. AS A RESULT...FLOODING REMAINS THE
MAIN CONCERN INTO THE EVENING HOURS. IF THIS ACTIVITY SETS UP OVER
THE SAME AREAS AS THIS MORNING WHERE 2-4 INCHES WERE
RECORDED...MAINLY FROM AROUND JUST SE OF CUTLER BAY TO NORTH MIAMI
BEACH...FLASH FLOODING CANNOT BE RULED OUT.
TONIGHT THROUGH SUNDAY NIGHT...THE COLD FRONT ENTERING THE REGION
FROM THE NORTH IS PROGGED TO CONTINUE SOUTH INTO NORTHERN AND
CENTRAL FLORIDA THROUGH THE FIRST HALF OF THE DAY SUNDAY FOLLOWED BY
A SURGE OF MUCH DRIER AIR BEFORE STALLING. UNFORTUNATELY...THE DEEP
LAY MOISTURE AXIS WITH AROUND 2" PWAT VALUES EXTENDING FROM NE TO SW
ACROSS THE AREA WILL REMAIN IN PLACE THROUGH SUNDAY WITH ONLY SOME
DRYING POSSIBLE ACROSS THE NORTHERN HALF OR THE LAKE REGION BY
TOMORROW NIGHT. THIS COMBINED WITH WEAK UPPER PULSES OF ENERGY
TRANSLATING NORTHEAST AHEAD OF THE BROAD UPPER TROUGH JUST WEST OF
THE AREA WILL KEEP THE RAIN AND FLOOD CHANCES AS THE PRIMARY
CONCERNS THROUGH SUNDAY. ADDITIONAL RAINFALL ACCUMULATIONS COULD
REACH THE 1 TO 3 INCH RANGE WITH LOCALIZED HIGHER AMOUNTS
POSSIBLE.
MONDAY AND MONDAY NIGHT...THE LATEST NUMERICAL GUIDANCE REMAINS IN
DECENT AGREEMENT AND INDICATES THE BROAD UPPER TROUGH OVER THE
EASTERN STATES SHIFTING EAST AND THE MUCH DRIER AIR THAT WAS
PREVIOUSLY DISCUSSED SHIFTING FARTHER SOUTH INTO OUR AREA IN THE
WAKE OF THE FRONTAL BOUNDARY. AS A RESULT...DRY AIR WITH LOWER
RAINFALL CHANCES CAN BE ANTICIPATED.
.LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO
S ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN
UPPER LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE
ATMOSPHERIC MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE
MAY NEAR THE AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH
GUIDANCE.
&&
.MARINE...
RAIN CHANCES WILL REMAIN UP ACROSS THE MARINE AREAS THROUGH SUNDAY
BEFORE DRIER AIR ASSOCIATED WITH A COLD FRONT SPREADS SOUTH ACROSS
THE AREA MONDAY. MODERATE NORTHEAST WINDS WILL FOLLOW THIS BOUNDARY
AND LEAD TO INCREASING SEAS MONDAY THROUGH TUESDAY OVER THE ATLANTIC
WATERS.
&&
.FIRE WEATHER...
ALTHOUGH SOME DRIER AIR IS FORECAST TO SPREAD SOUTH INTO THE AREA
THROUGH THE FIRST HALF OF THE UPCOMING WEEK...RELATIVE HUMIDITIES
ARE FORECAST TO REMAIN ABOVE CRITICAL LEVELS EACH DAY. AS A
RESULT...THERE ARE NO RED FLAG CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 81 77 86 / 80 60 50 20
FORT LAUDERDALE 75 86 75 86 / 90 70 50 30
MIAMI 75 88 75 88 / 80 70 60 30
NAPLES 74 87 74 89 / 80 40 40 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS MIAMI FL
133 PM EDT SAT SEP 22 2012
.AVIATION...
SHOWERS AND ISOLATED THUNDERSTORMS ARE REDEVELOPING ACROSS MIAMI
DADE COUNTY THIS AFTERNOON AHEAD OF A SHORTWAVE NEAR NAPLES. SO
HAVE VCTS FOR ALL AREAS EXCEPT KPBI WHERE ONLY SHOWERS WILL BE
POSSIBLE DUE TO THE CLOUD COVER. ADDED A TEMPO IN FOR KMIA AND
KTMB AS THE SHOWERS HAVE ALREADY BECOME MORE NUMEROUS THAT COUNTY.
LIGHT WINDS ARE EXPECTED EXCEPT IN ANY SHOWERS OR THUNDERSTORMS
THROUGH THE AFTERNOON AND EVENING HOURS. HIGH PRESSURE WILL BEGIN
TO BUILD INTO THE SOUTHEAST TONIGHT AND THE BOUNDARY NEAR THE LAKE
WILL BEGIN TO PUSH SOUTHWARD...AND A NORTHEAST WIND IS EXPECTED TO
DEVELOP. CANNOT RULE OUT SHOWERS ACROSS THE REGION OVERNIGHT...SO
LEFT VCSH IN AT ALL TAF SITES. THUNDERSTORMS WILL BE POSSIBLE ONCE
AGAIN EARLY SUNDAY MORNING THROUGH THE END OF THE TAF PERIOD AS
MOISTURE REMAINS HIGH. MOISTURE MAY BEGIN TO DECREASE NEAR KPBI
NEAR THE END OF THE TAF PERIOD.
&&
.PREV DISCUSSION... /ISSUED 1000 AM EDT SAT SEP 22 2012/
UPDATE...
A LARGE AREA OF HEAVY RAIN CONTINUES TO INCH NORTH ALONG THE EAST
COAST AND METRO AREAS OF SOUTH FLORIDA THIS MORNING. SOME AREAS
HAVE ALREADY RECORDED AMOUNTS INTO THE 2 TO 4 INCH RANGE. REPORTS
FROM THE MIAMI BEACH POLICE REPORTED FLOODING ALONG CHASE AVENUE
FROM ARTHUR GODFREY ROAD/WEST 41ST STREET TO ALTON ROAD WITH WATER
NEAR THE HOOD OF VEHICLES ON 20TH STREET WEST OF ALTON.
BASED ON THE LATEST RADAR TRENDS...RAINFALL RATES HAVE TRENDED
DOWN ACROSS MIAMI-DADE AND BROWARD WITH THE BEST RAINFALL RATES
NOW INCHING NORTH INTO PALM BEACH COUNTY WHERE RAINFALL AMOUNTS
HAVE ALREADY REACHED THE 1-1.5 INCH RANGE OVER THE PAST COUPLE OF
HOURS.
FOR THE REMAINDER OF THE DAY...THE LATEST HRRR RUN HAS INITIALIZED
WELL WITH THE CURRENT RAINFALL COVERAGE AND GENERALLY INDICATES A
LARGE PORTION OF THE LOCAL AREA GOING INTO A LULL THROUGH NOON AND
INTO THE EARLY AFTERNOON PERIOD BEFORE ANOTHER BATCH OF HEAVY RAIN
DEVELOPS AND SPREADS OVER THE AREA THROUGH THE MID-AFTERNOON
THROUGH THE EVENING HOURS ONCE AGAIN. AS A RESULT...FLOODING WILL
REMAIN THE MAIN CONCERN TODAY AS SOILS REMAIN SATURATED FROM
PREVIOUS RAINS. THE LATEST GRIDDED DATABASE HAS BEEN UPDATED WITH
THESE LATEST TRENDS AND NO OTHER UPDATES ARE NECESSARY AT THIS
TIME. 85/AG
PREV DISCUSSION... /ISSUED 744 AM EDT SAT SEP 22 2012/
AVIATION...
LARGE SHIELD OF SHRAS/TSRAS CONTINUE TO STREAM TO THE NORTH FROM THE
KEYS. A DEEP MOISTURE FIELD ALONG WITH A PASSING SURFACE TROUGH JUST
WEST OF THE FLORIDA KEYS WILL KEEP SHRAS AND EMBEDDED TSRA ACROSS
MUCH OF THE AREA THROUGH THE MORNING HOURS. PREVAILING MVFR
CONDITIONS ARE EXPECTED AT KTMB...KMIA...KOPF AND TOWARDS KFLL FOR
THE NEXT COUPLE OF HOURS AS THESE SHOWERS AND STORMS MOVE NORTH.
VIS/CIGS COULD DROP TO 1SM/1.5KFT IN THE HEAVIER THUNDERSTORMS.
CONTINUED WITH VCTS IN THE AFTERNOON AS A WEAK MID LEVEL
SHORTWAVE SWEEPS ACROSS SOUTH FLORIDA DURING THE PEAK HEATING
HOURS FURTHER ENHANCING SCATTERED TO WIDESPREAD TSRA DEVELOPMENT.
PREV DISCUSSION... /ISSUED 356 AM EDT SAT SEP 22 2012/
LONG TERM...(TUESDAY-FRIDAY)
THE UPPER RIDGE OVER THE ROCKIES BEGINS TO BREAK DOWN AS AN UPPER
LOW MOVES FROM THE PACIFIC NORTHWEST TOWARD THE CENTRAL ROCKIES.
THIS SHOVES THE E U.S. TROUGH NE WITH THE COLD FRONT STALLED N OF
LAKE OKEECHOBEE. THIS DRIES THE ATMOSPHERE SOMEWHAT FROM THE N TO S
ACROSS FLA BUT LONG RANGE MODELS STILL APPEAR TO DEVELOP AN UPPER
LOW OVER THE GULF AND WITH THE SW FLOW MAY KEEP AMPLE ATMOSPHERIC
MOISTURE OVER THE AREA. PLUS...ANOTHER TROPICAL WAVE MAY NEAR THE
AREA MIDWEEK NEXT WEEK. AT HIS TIME...WILL STAY WITH GUIDANCE.
MARINE...
EASTERLY WINDS LESS THAN 15 KNOTS WILL PERSIST THROUGH THE PERIOD
WITH WEEKEND WITH SEAS 4 FEET OR LESS.
FIRE WEATHER...NO CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 88 74 87 / 50 40 30 30
FORT LAUDERDALE 75 88 76 87 / 50 40 30 40
MIAMI 75 88 75 87 / 50 40 30 40
NAPLES 73 88 73 92 / 30 30 20 30
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...85/AG
AVIATION/RADAR...84/AK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1238 PM CDT SAT SEP 22 2012
.SHORT TERM /TODAY/...
MAIN FORECAST CONCERN IS WITH WINDS AND TEMPS
TODAY WITH STRONG CAA DEVELOPING BEHIND THE COLD FRONT THAT PUSHED
ACROSS MUCH OF THE CWA EARLY THIS MORNING. LEANED TOWARD A
NAM/RAP/SREF BLEND TODAY AS ALL MODELS ARE IN GOOD AGREEMENT. 03Z
HRRR/05Z RAP DEPICT A STRATUS DECK LOCATED IN NORTHERN MN TO ARRIVE
IN NORTHERN IOWA BY AROUND 12Z AND THEN DISSIPATE BY AROUND 18Z.
INCREASED CLOUD COVER OVER THE NORTH TO NORTHEAST THIS MORNING AS A
RESULT. THIS WILL HINDER THE MAX TEMP SLIGHTLY AND WENT A LITTLE
COOLER IN THIS AREA. OTHERWISE...STRONG NORTHWEST WINDS WILL BE
COMMON THROUGHOUT THE DAY WITH FAIRLY TIGHT PRESSURE GRADIENT AND
DECENT MIXING BEFORE HIGH SETTLES IN LATE THIS AFTERNOON. TWEAKED
WINDS UP SLIGHTLY WITH THIS SCENARIO AS CURRENT WINDS UPSTREAM ARE
GUSTING TO 20-25KTS.
.LONG TERM /TONIGHT THROUGH FRIDAY/...
COLD CANADIAN HIGH PRESSURE WILL INTO CENTRAL IOWA TONIGHT. THE HIGH
WILL REINFORCE THE VERY DRY AIR THAT IS FELTING INTO THE STATE THIS
MORNING AND EXPECT DEWPOINTS OVERNIGHT TO BE WELL INTO THE 20S OVER
THE NORTH AND WEST. CURRENTLY A LARGE ARE OF STRATUS ALONG THE
EASTERN FRINGE OF THE HIGH THUS THERE IS SOME UNCERTAINTY THAT THIS
STRATUS MAY AFFECT AREAS EAST OF INTERSTATE 35 OVERNIGHT AND PROVIDE
ENOUGH INSOLATION TO HOLD READINGS UP. 925 MB WIND TRAJECTORIES
REMAIN ROUGHLY 340-360 DEGREES THROUGH TODAY AND TONIGHT. MUCH OF
THE REGION SHOULD HAVE ENOUGH SUBSIDENCE WITH THE APPROACHING HIGH
TO ERODE MUCH OF IT. FOR AREAS THAT HAVE MOSTLY CLEAR SKIES...THE
DIMINISHING WINDS AND VERY DRY AIR WILL ALLOW TEMPERATURES TO
PLUMMET OVERNIGHT TO RECORD OR NEAR RECORD LOW VALUES. THESE VALUES
ARE BELOW FREEZING FOR ALL LOCATIONS EXCEPT THE FAR SOUTH AND
SOUTHEAST. HAVE ISSUED A FREEZE WARNING FOR ALL LOCATIONS WITH
FORECAST LOWS BELOW 32 TONIGHT. HAVE LEFT THE FREEZE WATCH OUT FOR
THE SOUTH CENTRAL WHERE READINGS WILL BE A BIT WARMER. GIVEN THE
VERY DRY AIR...FROST MAY NOT BE PREVALENT IN THESE AREAS DESPITE THE
TEMPERATURES SO NO CONFIDENCE IN FROST HEADLINES IN THAT REGION.
KEEPING THE FREEZE WATCH WILL GIVE THE FOLLOWING SHIFT SOME WIGGLE
ROOM WITH THE HEADLINES IF MORE COLD AIR THAN ANTICIPATED ARRIVES BY
TONIGHT.
SUNDAY WILL BE PLEASANT THOUGH COOL WITH MOSTLY SUNNY SKIES AND
LIGHT NORTHWEST WINDS. HIGH PRESSURE SLIDES TO THE SOUTHEAST SUNDAY
NIGHT. WILL HAVE QUICK COOLING SUNDAY EVENING BEFORE SOUTHERLY FLOW
GRADUALLY RETURNS LATE. POSSIBLE FOR NEAR FREEZING TEMPERATURES
AGAIN OVER THE NORTHEAST WHERE RETURN FLOW WILL ARRIVE LAST.
READINGS WILL BE MILD MONDAY AND TUESDAY WITH 850 MB THERMAL RIDGING
MOVES INTO THE STATE. MORE UNCERTAINTY ARRIVES FOR WEDNESDAY THROUGH
FRIDAY WITH THE TRANSITION FROM NORTHWEST TO ZONAL FLOW OCCURS. THE
TRANSITION WILL ALLOW THE ENERGY FROM WEST COAST UPPER LOW AND A
PACIFIC NORTHWEST SYSTEM TO MOVE TOWARD THE REGION WHILE A MID LEVEL
BOUNDARY LIFTS TOWARD THE STATE. CURRENTLY HAVE SEVERAL PERIODS WITH
POPS WITH THE BEST POTENTIAL WEDNESDAY NIGHT THROUGH THURSDAY NIGHT.
THE 500 MB FLOW DURING THIS PERIOD IS UNORGANIZED ENOUGH THAT IT IS
GIVING GUIDANCE PROBLEMS ON EXACT PLACEMENT OF WHERE THE SHORTWAVES
WILL MOVE THROUGH.
&&
.AVIATION...22/18Z
MVFR AREA OF SC OVER NERN IA WILL PERSIST FOR A FEW MORE HOURS
BEFORE IT STARTS TO DISSIPATE. SHOULD BREAK UP TO A SCATTERED LAYER
BY 22Z OR SO. HIGH PRESSURE WILL BUILD INTO THE STATE TONIGHT WITH
WINDS DIMINISHING RAPIDLY AROUND SUNSET. LIGHT WINDS AND CLEAR
SKIES THROUGH THE REST OF THE FORECAST PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING LATE TONIGHT THROUGH SUNDAY MORNING FOR
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-
WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-
GREENE-BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-CASS-
ADAIR-ADAMS-TAYLOR-
FREEZE WATCH LATE TONIGHT THROUGH SUNDAY MORNING FOR
POLK-JASPER-POWESHIEK-MADISON-WARREN-MARION-MAHASKA-UNION-CLARKE-
LUCAS-MONROE-WAPELLO-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
&&
$$
SHORT TERM...PODRAZIK
LONG TERM...DONAVON
AVIATION...MS SEP 12
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
356 PM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TONIGHT AND EARLY SUNDAY. HIGH
PRESSURE RETURNS FOR THE FIRST HALF OF NEXT WEEK. ANOTHER COLD
FRONT MOVES ACROSS THE REGION EARLY THURSDAY...FOLLOWED BY HIGH
PRESSURE BUILDING IN FROM THE NORTH LATE THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SURFACE COLD FRONT CONINTUES MOVING EASTWARD TOWARD WESTERN VA. CU
FIELD BEGINNING TO INCREASE ALONG/JUST EAST OF THE MTNS...ALTHOUGH
NO SHWRS/TSTMS HAVE DVLPD ATTM. EXPECT A NARROW BAND OF
SHWRS/ISOLATED TSTMS TO DEVELOP ALONG/JUST AHD OF FRONT BY 20-21Z
JUST WEST OF CWA...THEN MOVE STEADILY EWD ACROSS CWA THROUGH 06Z.
BOTH HRRR AND RUC SUGGEST AN INCREASE IN AREAL COVERAGE OF
PRECIPITATION OVER PREVIOUS FORECAST...PRIMARILY SRN PTNS OF CWA. SO
HAVE INCREASED POPS A BIT ACROSS PTNS OF SE VA/NE NC. SPC
MESOANALYSIS PAGE SUGGESTS SFC CAPE IN TO 1000-1500 J/KG RANGE...BUT
MIXED LAYER CAPE BARELY REACHES 1000 J/KG. THUS...DO NOT SEE A LOT OF
TSTM ACTVTY OCCURRING..AND HAVE MAINTAINED ISOLATED WORDING IN
GRIDS/TEXT PRODUCTS. ENOUGH OF AN INVERTED VEE SHAPE TO LOWEST
PART OF SOUNDINGS TO SUGGEST ANY TSTMS COULD BE ACCOMPANIED BY
GUSTY WINDS. SVR THREAT...HWVR...APPEARS SMALL. MIN TEMPS LITTLE
CHANGED FROM PREVIOUS FORECAST...WITH MOST INLAND AREAS DROPPING
INTO THE 50S...AND CSTL SECTIONS IN THE 60-65 RANGE.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
DRY WEATHER AND MOSTLY CLR SKIES ANTICIPATED SUN/MON AS HIGH
PRESSURE MOVES INTO REGION FROM THE MIDWEST. ANY PRECIP ASSOCIATED
WITH COLD FRONT EXPECTED TO BE OFFSHORE AND OUT OF THE AREA BY
12Z. MAX TEMPS SUN AROUND 70 NW SECTIONS TO MID 70S PTNS NE NC. A
LITTLE COOLER MONDAY WITH MOST AREAS IN THE 70-74 RANGE. MIN TEMPS
BOTH SUN/MON NIGHTS MAINLY IN THE 40S UNDER CLR SKIES/LIGHT WINDS.
DEEPER WARM ADVECTION AHEAD OF MIDWEST TROF WILL CAUSE AN INCREASE
IN MID/HIGH CLOUDS ON TUESDAY. THESE CLOUDS WILL KEEP MAX TEMPS
FROM REACHING POTENTIAL WRN/CNTRL SECTIONS OF CWA..ALTHOUGH ALL
AREAS EXPECTED TO GET INTO THE LOW/MID 70S.
DRIER AIR COMING INTO AREA...ALONG WITH DECENT DAYTIME MIXING...WILL
FAVOR AFTERNOON SURFACE DEW POINTS A FEW DEGREES LOWER THAN
GUIDANCE...AND HAVE GONE CLOSE TO NAM MIXED LAYER DEW POINTS EACH
AFTERNOON SUNDAY THROUGH TUESDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE LAST HALF OF THE UPCOMING WEEK LOOKS TO BE MAINLY DRY WITH NEAR
TO SLIGHTLY ABOVE NORMAL TEMPERATURES. A DEEP UPPER LEVEL LOW OVER
EASTERN CANADA WILL SWING A TROUGH THROUGH THE NORTHEASTERN STATES.
UPPER LEVEL RIDGING OVER WESTERN CANADA WILL SHIFT EAST AND THE
RESULT WILL BE INCREASING 50H HEIGHTS OVER THE SOUTHEASTERN STATES
LATE NEXT WEEK.
MODELS ARE IN FAIRLY GOOD AGREEMENT WITH BRINGING A COLD FRONT
THROUGH THE MID ATLANTIC STATES EARLY THURSDAY...ABOUT 6 TO 12 HOURS
EARLIER THAN THEY DID FRIDAY. DUE TO THE AFOREMENTIONED RIDGING TO
OUR SW...THE FRONT WILL HAVE MINIMAL EFFECT ON PCPN OR COOLING. THE
WARMEST DAY APPEARS TO BE WEDNESDAY BUT TEMPERATURES AT 85H ONLY
FALL SLIGHTLY BEHIND THE FRONT THURSDAY AND FRIDAY. MOISTURE WILL BE
LIMITED ALONG THE FRONT AND KEPT POPS AOB 20 PERCENT THROUGH THE
PERIOD.
HIGH TEMPERATURES IN THE UPR 70S TO LWR 80S WEDNESDAY AND COOL
SLIGHTLY TO THE MID 70S TO AROUND 80 THURSDAY. CLOUD COVER FROM WEAK
SHORT WAVES AND POSSIBLY SOME UPSLOPE LOW LEVEL FLOW MAY HOLD
TEMPERATURES DOWN A BIT FRIDAY AND SATURDAY AND KEPT HIGHS IN THE
70S.
FORECAST LOWS RANGE FROM THE 50S INLAND TO THE LOWER 60S NEAR THE
COAST THROUGH THE PERIOD.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
SOUTHWEST WINDS GUSTING AROUND 20KT WILL CONTINUE THROUGH SUNSET
IN ADVANCE OF AN APPROACHING COLD FRONT. SCT LATE AFTN CU SHOULD
DEVELOP INTO A BKN DECK AROUND 5K FT THIS EVENING AS THE FRONT
MOVES INTO THE AREA. MODELS BRING THE BEST CHANCE OF WIDESPREAD
LIGHT PRECIP TO THE NORTHERN NECK/EASTERN SHORE (KSBY) AFTER DARK
THIS EVENING. HAVE A PREVAILING GROUP FOR VFR SHOWERS AT KSBY FROM
02Z-06Z. MEANWHILE...HAVE VCSH AT ALL OTHER TAF SITES THIS
EVENING AS CONFIDENCE IN PRECIP IS NOT AS HIGH. WILL SEE HOW THE
RADAR LOOKS BEFORE THE 00Z PACKAGE AND ADJUST AS NECESSARY. DRY WX
RETURNS BEHIND THE FROPA OVERNIGHT/SUNDAY WITH WINDS VEERING TO
THE NORTH. HIGH PRESSURE RETURNS TO THE MID ATLANTIC REGION SUNDAY
THROUGH MOST OF NEXT WEEK.
&&
.MARINE...
SCA IN EFFECT FOR ALL OF THE WATERS TNGT AND EARLY SUNDAY AS A
NORTHERLY SURGE DEVELOPS BEHIND A STRONG COLD FRONT. SEAS WERE
APPROACHING 5 FT AT BUOY 09 AND KEPT SCA NORTH OF PARRAMORE ISLAND
THAT BEGINS AT 21Z. THE REST OF THE WATERS EXCEPT CURRITUCK SOUND
HAVE SCA BEGIN AT 00Z. MOST OF THE SCA CONDITIONS SHOULD HOLD OFF
UNTIL AFTER FRONTAL PASSAGE...BETWEEN 03 AND 06Z AND CONTINUE INTO
THE COASTAL WATERS BETWEEN 06 AND 09Z. SCA BEGINS OVER CURRITUCK
SOUND AT 06Z.
WINDS INCREASE FROM THE NORTH TO BETWEEN 20 AND 25 KNOTS OVER THE
BAY AND COASTAL WATERS BEFORE DIMINISHING IN THE LATE MORNING.
CURRENT SCA IN EFFECT OVER BAY AND INLAND WATERS UNTIL 18Z MAY BE
LIFTED PRIOR TO THAT.
THE SCA FOR THE COASTAL WATERS SUNDAY AFTN WILL BE MAINLY PREDICATED
ON THE SUSTAINING OF 5 FT SEAS WHICH IS QUESTIONABLE AT THIS POINT.
CURRENT GRIDS HAVE 5 FT SEAS CONTINUING THROUGH 12Z MONDAY.
A SECONDARY SURGE IS EXPECTED MONDAY MORNING...MAINLY SUPPORTED BY
MOS GUIDE AND A TIGHTENING OF THE PRESSURE GRADIENT. IT APPEARS
THAT MOST OF THE IMPACT OF THIS SURGE WILL BE OVER THE SOUTHERN
COASTAL WATERS. THE NEED FOR AN SCA IS UNCERTAIN AT THIS TIME.
QUIET MARINE CONDITIONS ARE EXPECTED FOR MUCH OF THE UPCOMING WEEK
BEYOND MONDAY.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 2 PM EDT SUNDAY
FOR ANZ630>632-634>636-638.
SMALL CRAFT ADVISORY FROM 2 AM TO 2 PM EDT SUNDAY FOR ANZ633.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT SUNDAY
FOR ANZ654-656-658.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT SUNDAY FOR ANZ650-652.
&&
$$
SYNOPSIS...LSA/WRS
NEAR TERM...WRS
SHORT TERM...WRS
LONG TERM...LSA
AVIATION...BMD/JDM
MARINE...LSA
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
227 PM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA TONIGHT AND EARLY SUNDAY. HIGH
PRESSURE RETURNS FOR THE FIRST HALF OF NEXT WEEK. ANOTHER COLD
FRONT MOVES ACROSS THE REGION LATE WEDNESDAY AND WEDNESDAY
NIGHT...FOLLOWED BY HIGH BUILDING IN FROM THE NORTH ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SURFACE COLD FRONT CONINTUES MOVING EASTWARD TOWARD WESTERN VA. CU
FIELD BEGINNING TO INCREASE ALONG/JUST EAST OF THE MTNS...ALTHOUGH
NO SHWRS/TSTMS HAVE DVLPD ATTM. EXPECT A NARROW BAND OF
SHWRS/ISOLATED TSTMS TO DEVELOP ALONG/JUST AHD OF FRONT BY 20-21Z
JUST WEST OF CWA...THEN MOVE STEADILY EWD ACROSS CWA THROUGH 06Z.
BOTH HRRR AND RUC SUGGEST AN INCREASE IN AREAL COVERAGE OF
PRECIPITATION OVER PREVIOUS FORECAST...PRIMARILY SRN PTNS OF CWA. SO
HAVE INCREASED POPS A BIT ACROSS PTNS OF SE VA/NE NC. SPC
MESOANALYSIS PAGE SUGGESTS SFC CAPE IN TO 1000-1500 J/KG RANGE...BUT
MIXED LAYER CAPE BARELY REACHES 1000 J/KG. THUS...DO NOT SEE A LOT OF
TSTM ACTVTY OCCURRING..AND HAVE MAINTAINED ISOLATED WORDING IN
GRIDS/TEXT PRODUCTS. ENOUGH OF AN INVERTED VEE SHAPE TO LOWEST
PART OF SOUNDINGS TO SUGGEST ANY TSTMS COULD BE ACCOMPANIED BY
GUSTY WINDS. SVR THREAT...HWVR...APPEARS SMALL. MIN TEMPS LITTLE
CHANGED FROM PREVIOUS FORECAST...WITH MOST INLAND AREAS DROPPING
INTO THE 50S...AND CSTL SECTIONS IN THE 60-65 RANGE.
&&
.SHORT TERM /SUNDAY THROUGH TUESDAY/...
DRY WEATHER AND MOSTLY CLR SKIES ANTICIPATED SUN/MON AS HIGH
PRESSURE MOVES INTO REGION FROM THE MIDWEST. ANY PRECIP ASSOCIATED
WITH COLD FRONT EXPECTED TO BE OFFSHORE AND OUT OF THE AREA BY
12Z. MAX TEMPS SUN AROUND 70 NW SECTIONS TO MID 70S PTNS NE NC. A
LITTLE COOLER MONDAY WITH MOST AREAS IN THE 70-74 RANGE. MIN TEMPS
BOTH SUN/MON NIGHTS MAINLY IN THE 40S UNDER CLR SKIES/LIGHT WINDS.
DEEPER WARM ADVECTION AHEAD OF MIDWEST TROF WILL CAUSE AN INCREASE
IN MID/HIGH CLOUDS ON TUESDAY. THESE CLOUDS WILL KEEP MAX TEMPS
FROM REACHING POTENTIAL WRN/CNTRL SECTIONS OF CWA..ALTHOUGH ALL
AREAS EXPECTED TO GET INTO THE LOW/MID 70S.
DRIER AIR COMING INTO AREA...ALONG WITH DECENT DAYTIME MIXING...WILL
FAVOR AFTERNOON SURFACE DEW POINTS A FEW DEGREES LOWER THAN
GUIDANCE...AND HAVE GONE CLOSE TO NAM MIXED LAYER DEW POINTS EACH
AFTERNOON SUNDAY THROUGH TUESDAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THE LAST HALF OF THE UPCOMING WEEK LOOKS TO BE MAINLY DRY WITH NEAR
TO SLIGHTLY ABOVE NORMAL TEMPERATURES. A DEEP UPPER LEVEL LOW OVER
EASTERN CANADA WILL SWING A TROUGH THROUGH THE NORTHEASTERN STATES.
UPPER LEVEL RIDGING OVER WESTERN CANADA WILL SHIFT EAST AND THE
RESULT WILL BE INCREASING 50H HEIGHTS OVER THE SOUTHEASTERN STATES
LATE NEXT WEEK.
MODELS ARE IN FAIRLY GOOD AGREEMENT WITH BRINGING A COLD FRONT
THROUGH THE MID ATLANTIC STATES EARLY THURSDAY...ABOUT 6 TO 12 HOURS
EARLIER THAN THEY DID FRIDAY. DUE TO THE AFOREMENTIONED RIDGING TO
OUR SW...THE FRONT WILL HAVE MINIMAL EFFECT ON PCPN OR COOLING. THE
WARMEST DAY APPEARS TO BE WEDNESDAY BUT TEMPERATURES AT 85H ONLY
FALL SLIGHTLY BEHIND THE FRONT THURSDAY AND FRIDAY. MOISTURE WILL BE
LIMITED ALONG THE FRONT AND KEPT POPS AOB 20 PERCENT THROUGH THE
PERIOD.
HIGH TEMPERATURES IN THE UPR 70S TO LWR 80S WEDNESDAY AND COOL
SLIGHTLY TO THE MID 70S TO AROUND 80 THURSDAY. CLOUD COVER FROM WEAK
SHORT WAVES AND POSSIBLY SOME UPSLOPE LOW LEVEL FLOW MAY HOLD
TEMPERATURES DOWN A BIT FRIDAY AND SATURDAY AND KEPT HIGHS IN THE
70S.
FORECAST LOWS RANGE FROM THE 50S INLAND TO THE LOWER 60S NEAR THE
COAST THROUGH THE PERIOD.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
SOUTHWEST WINDS GUSTING AROUND 20KT WILL CONTINUE THROUGH SUNSET
IN ADVANCE OF AN APPROACHING COLD FRONT. SCT LATE AFTN CU SHOULD
DEVELOP INTO A BKN DECK AROUND 5K FT THIS EVENING AS THE FRONT
MOVES INTO THE AREA. MODELS BRING THE BEST CHANCE OF WIDESPREAD
LIGHT PRECIP TO THE NORTHERN NECK/EASTERN SHORE (KSBY) AFTER DARK
THIS EVENING. HAVE A PREVAILING GROUP FOR VFR SHOWERS AT KSBY FROM
02Z-06Z. MEANWHILE...HAVE VCSH AT ALL OTHER TAF SITES THIS
EVENING AS CONFIDENCE IN PRECIP IS NOT AS HIGH. WILL SEE HOW THE
RADAR LOOKS BEFORE THE 00Z PACKAGE AND ADJUST AS NECESSARY. DRY WX
RETURNS BEHIND THE FROPA OVERNIGHT/SUNDAY WITH WINDS VEERING TO
THE NORTH. HIGH PRESSURE RETURNS TO THE MID ATLANTIC REGION SUNDAY
THROUGH MOST OF NEXT WEEK.
&&
.MARINE...
A TIGHTENING PRESSURE GRADIENT IN RESPONSE TO AN APPROACHING COLD
FRONT WILL CREATE BREEZY CONDITIONS OVER THE WATERS BY LATE
MORNING/EARLY AFTN TODAY. EXPECT S WINDS OF GENERALLY 10-15 KT WITH
SEAS OF 3-4 FT OVER OCEAN WATERS. THE COLD FRONT IS PUSHING THROUGH
THE REGION A LITTLE FASTER THAN MODEL RUNS YESTERDAY...HAVING MORE
OF AN 8 PM TO MIDNIGHT PASSAGE RATHER THAN MIDNIGHT THROUGH EARLY
SUNDAY MORNING. THE EARLIER TIMING WILL ACT TO FURTHER ENHANCE CAA
BEHIND THE FRONT AND THUS HELP TO PRODUCE SLIGHTLY STRONGER SCA
CONDITIONS AS WINDS SHIFT TO THE NNW. ADDITIONALLY...AS THE FRONT
MOVES OFFSHORE AND HIGH PRESSURE QUICKLY BUILDS IN...THE PRESSURE
GRADIENT TIGHT WILL REMAIN TIGHT AND FURTHER DESTABILIZE THE MARINE
BOUNDARY LAYER. AS CAA COMMENCES...SEAS ARE ALSO EXPECTED TO RISE TO
4-5 FT (POSSIBLY UP TO 6 FT OUT NEAR 20 NM). SCA FLAGS HAVE BEEN
ISSUED FOR AREA WATERS MAINLY STARTING AT 8 PM TONIGHT THROUGH 2 PM
SUNDAY AFTERNOON...WITH MINOR TIMING ADJUSTMENTS FOR NRN OCEAN ZONES
AND CURRITUCK SOUND. PLEASE REFERENCE THE SMALL CRAFT ADVISORY (OR
WBCMWWAKQ) FOR FURTHER DETAILS AT WWW.WEATHER.GOV/WAKEFIELD.
N WINDS ARE EXPECTED TO SUBSIDE SUNDAY AFTERNOON. HOWEVER...THE
PRESSURE GRADIENT TIGHTENS UP AGAIN SUNDAY NIGHT AND A REINFORCING
SHOT OF COLD AIR WILL PUSH DOWN FROM THE NNW. THIS COULD PRODUCE
ANOTHER ROUND OF SCA WINDS OF 15-20 KT FOR THE
BAY/RIVERS/SOUND...BUT WILL LET CURRENT HEADLINE TAKE PRECEDENCE
BEFORE TACKLING POTENTIAL FLAGS FOR SUNDAY NIGHT. SEAS WILL LIKELY
STAY ABOVE 5 FT TONIGHT THROUGH MONDAY MORNING WILL ONLY HOLD ONTO
SCA FOR OCEAN WATERS FOR TONIGHT-SUNDAY FOR NOW. OTHERWISE...HIGH
PRESSURE DOMINATES THE WX PATTERN MONDAY THROUGH MOST OF NEXT WEEK
AND WILL RESULT IN MORE BENIGN CONDITIONS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 2 PM EDT SUNDAY
FOR ANZ630>632-634>636-638.
SMALL CRAFT ADVISORY FROM 5 AM TO 2 PM EDT SUNDAY FOR ANZ633.
SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT SUNDAY
FOR ANZ654-656-658.
SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 8 PM EDT
SUNDAY FOR ANZ650-652.
&&
$$
SYNOPSIS...MAM/WRS
NEAR TERM...WRS
SHORT TERM...WRS
LONG TERM...LSA
AVIATION...BMD/JDM
MARINE...LSA
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
139 PM EDT SAT SEP 22 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 525 AM EDT SAT SEP 22 2012
1004MB SFC LOW IS CURRENTLY JUST TO THE EAST OF LK SUPERIOR AND
LOCATED ON THE EASTERN EDGE OF THE PERSISTENT UPPER TROUGH THAT HAS
BEEN OVER THE UPPER GREAT LAKES REGION. THERE ARE A COUPLE
SHORTWAVES OF NOTE THAT WILL BE AFFECTING THE AREA TODAY AND
TONIGHT. THE FIRST WAVE IS LOCATED OVER NW WI AND DROPPING TO THE
SE. THIS HAS PRODUCED SCATTERED SHOWERS OVER FAR WESTERN UPPER
MICHIGAN AND LK SUPERIOR. AS THIS SHORTWAVE HAS STARTED TO SLIDE TO
THE S...A SFC TROUGH STRETCHING E TO W ACROSS SRN LK SUPERIOR HAS
ALSO BEEN SLIDING S AND HELPED PRODUCE A FEW SHOWERS AND AN ISOLATED
THUNDERSTORM. WINDS ARE QUICKLY TURNING TO THE N AND GUSTING TO
25KTS BEHIND THIS TROUGH. THE OTHER SHORTWAVE IS LOCATED OVER NW
ONTARIO AND QUICKLY DROPPING SOUTH.
TODAY...SHORTWAVE DIVING SE THROUGH WI THIS MORNING HAS STARTED TO
USHER IN COLDER H850 TEMPS OVER THE AREA TODAY...WITH RUC ANALYZED
VALUES FALLING FROM AROUND 0 TO -1C AT 00Z TODAY TO -2 TO -3C AT
08Z. THESE COOLER TEMPS ALOFT AND ADDITIONAL MOISTURE BEHIND THE
FIRST SHORTWAVE MOVING THROUGH NW WI THIS MORNING WILL LEAD TO AN
UPTICK IN LK ENHANCED SHOWERS THIS MORNING...ESPECIALLY ALONG AND
RIGHT BEHIND THE SFC TROUGH. BUT A POCKET OF DRIER H850-700 MOISTURE
OVER THE WESTERN CWA SHOULD KEEP THE SHOWERS OVER THE WEST FROM
BECOMING TOO WIDESPREAD AND STRONG. THEY MAY EVEN END DURING THE
LATE MORNING AND EARLY AFTERNOON...AS THERE IS LIMITED MOISTURE SEEN
TOWARDS THUNDER BAY AND SRN ONTARIO. MODELS ARE SHOWING ENOUGH
SHALLOW MOISTURE TO SUPPORT AT LEAST LK ENHANCED CLOUDS DURING THAT
DRIER PERIOD. FARTHER EAST...DEEPER MOISTURE IS IN PLACE UNDER THE
UPPER TROUGH AND WITH THE COLD AIR ALOFT...EXPECT LK ENHANCED
SHOWERS TO BECOME MORE WIDESPREAD THROUGH THE DAY. THEN AS THE
SECONDARY SHORTWAVE...CURRENTLY IN NW ONTARIO...ARRIVES IN THE
MID-LATE AFTN AND CONTINUES INTO THE EVENING WITH THE CONTINUED
COOLING ALOFT...EXPECT LK ENHANCED SHOWERS AIDED BY THE SHORTWAVE TO
REALLY TAKE OFF ACROSS ALL BUT THE SCNTRL CWA.
THE BIGGEST ISSUE FOR TODAY MAY BE POTENTIAL FOR THUNDER AND
GRAUPEL. THE COLD AIR ALOFT WILL HELP STEEPEN LLVL LAPSE RATES AND
LEAD TO STRONGER UPDRAFTS. BUFKIT LK INDUCED CAPE VALUES HAVE BEEN
FAIRLY IMPRESSIVE...500-1250 J/KG...BUT MODIFYING SOUNDINGS TO LOW
50S OVER LOW-MID 40S WOULD INDICATE CAPES STAYING IN THE 300-500
J/KG RANGE. OVER THE LAST COUPLE DAYS IT SEEMS THE LIGHTNING HAS
OCCURRED WHERE ADDITIONAL FORCING HAS BEEN PRESENT
/E.G. SHORTWAVE...CONVERGENCE ALONG FRONT/. THUS...EXPECT A
LULL IN THUNDER CHANCES AFTER THE TROUGH MOVES THROUGH AND
THEN REDEVELOP TOWARDS AFTN WHEN SHORTWAVE ARRIVES AND PEAK HEATING
IS HERE. AS FOR GRAUPEL...WILL CONTINUE TO MENTION POTENTIAL WITH
THE STRENGTH OF THE UPDRAFTS. PUSHED THE PROBABILITIES UP HEADING
INTO THE AFTN WITH THE APPROACHING SHORTWAVE AND DEEPER MOISTURE.
AS FOR WINDS...H950-850 WINDS ARE GENERALLY IN THE 30-35KT
RANGE...SO EXPECT GALES TO 35-37KTS TO BE THE NORM. THINKING WITH
LITTLE VARIABILITY IN THE WINDS IN THAT LAYER AND THE STRONG
PRESSURE GRADIENT...IT WILL LIKELY BE SUSTAINED WINDS TOWARDS
25-30KTS AND THEN GUSTS TOWARDS THAT 35KT RANGE. WITH LITTLE
ADDITIONAL SUPPORT FROM ISALLOBARIC FEATURES...DON/T EXPECT THE
GUSTS TO GET MUCH HIGHER THAN THE MODELS ARE SHOWING OVER ERN LK
SUPERIOR AND SHOULDN/T REACH ADVY CRITERIA NEAR THE LAKESHORE OVER
ALGER/LUCE COUNTIES.
TONIGHT...TIGHT PRESSURE GRADIENT WILL SHIFT SE OF THE CWA...AS HIGH
PRESSURE OVER THE NRN PLAINS BEGINS TO SLOWLY APPROACH THE AREA. THE
SHORTWAVE THAT ARRIVES OVER THE NW HALF OF THE CWA IN THE AFTN WILL
PUSH THROUGH THE CWA DURING THE EVENING HOURS. WILL KEEP HIGHER
POPS OVER LOCATIONS NEAR LAKE SUPERIOR DURING THE EVENING HOURS
DUE TO LK ENHANCEMENT. AS THE SHORTWAVE MOVES SE OF THE CWA...EXPECT
A TRANSITION TO JUST LK ENHANCED SHOWERS WITH H850 TEMPS AROUND -3
TO -4C. DRYING ALOFT FROM THE HIGH WILL ALLOW THE LK ENHANCED
SHOWERS TO BECOME FOCUSED FARTHER EAST WHERE THE DEEPEST MOISTURE
REMAINS THROUGH THE NIGHT. STILL THINK THERE WILL BE ENOUGH
MOISTURE FOR SCATTERED SHOWERS OUT WEST WITH THE SHORTER FETCH.
COULD BE SOME DECENT RAINS OVER THE ERN CWA DEPENDING ON WHERE THE
SHOWERS LINE UP. APPEARS TO BE SOME ENHANCED CONVERGENCE IN THAT
AREA WITH THE APPROACHING HIGH...NNW OVER THE FAR ERN LK AND
BACKING TO THE NW-WNW OVERNIGHT OVER WRN LK SUPERIOR. WITH THE
VERY DEEP CLOUD/CONVECTIVE LAYER...COULD EASILY SEE AREAS TOWARDS
MUNISING ENDING UP WITH OVER AN INCH OF RAIN BY SUNDAY MORNING.
WILL LEAVE A SLIGHT CHANCE MENTION OF SNOW IN OVER THE
WRN CWA...BUT MODEL SOUNDING PROFILES SHOW A COUPLE FEATURES
LIMITING POTENTIAL. FIRST...BEST LLVL FORCING COINSIDING WITH THE
CLOUD LAYER IS IN THE -1 TO -5C TEMP RANGE...WHICH LIMITS ICE IN
THE CLOUD. SECOND...WBZ VALUES IN THE 1200-1500 FT RANGE WOULD
INDICATE ONLY A LOW POTENTIAL FOR SNOW TO MAKE IT TO THE SFC IF
THERE IS ACTUALLY ICE/SNOW PRESENT IN THE CLOUD. BUT IF GFS
SOUNDINGS ARE CORRECT WITH A SLIGHTLY COLDER AND DEEPER CLOUD
DEPTH...SNOW WOULD BE MORE LIKELY.
AS FOR WATERSPOUTS OVER THE LAKES TODAY AND TONIGHT...SWI INDICATES
VERY FAVORABLE CONDITIONS...APPROACHING 7-9...DUE TO DEEP CONVECTIVE
LAYER AND SFC-850 DELTA-T VALUES AROUND 15-17. THE ONLY DRAWBACK IS
THE STRONG WINDS THIS AFTN. WITH H850 WINDS AROUND 30-35KTS...THIS
IS ON THE HIGH END FOR WATERSPOUT POTENTIAL THROUGH THE DAY TODAY.
IF WINDS END UP A LITTLE LOWER THAN EXPECTED...COULD SEE POTENTIAL
INCREASE. WITH WINDS DECREASING TONIGHT...HAVE ADDED THE POTENTIAL
BACK OVER THE ERN HALF OF LK SUPERIOR...ESPECIALLY WITH THE ADDED
CONVERGENCE AND EXPECTED AREA OF STRONGER SHOWERS.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 525 AM EDT SAT SEP 22 2012
MEDIUM RANGE GUIDANCE IS IN GENERAL AGREEMENT ON THE BIG PICTURE
OVER THE NEXT 7 DAYS. CURRENT COOL PATTERN FOR UPPER MI WILL PEAK
TODAY/SUN AS TROF REACHES PEAK AMPLITUDE. COOL WEATHER WILL CONTINUE
INTO THE EARLY PART OF THE UPCOMING WEEK AS RIDGE REMAINS OVER WRN
NAMERICA WITH DOWNSTREAM TROF EXTENDING S THRU THE GREAT LAKES...
THOUGH THERE WILL BE A SHARP WARM UP MON AHEAD OF THE NEXT SHORTWAVE
DROPPING INTO THE TROF. INTO THE MIDDLE/END OF THE WEEK...TROF WILL
WEAKEN/LIFT OUT AS UPSTREAM RIDGE DEAMPLIFIES SOME AND PROGRESSES
E...BUT IT APPEARS MORE ENERGY MAY DROP SE INTO THE NE CONUS LATE
WEEK...PREVENTING A MORE SUSTAINED WARMING TREND FROM TAKING HOLD
HERE. HOWEVER...TEMPS WILL STILL RETURN TO MORE TYPICAL LATE SEPT
VALUES. PCPN CHANCES WILL BE HIGHEST TODAY/SUN UNDER THE DEEP TROF
OVER THE AREA. TREND WILL THEN BE TOWARD DRY WEATHER DURING THE
UPCOMING WEEK AS TROF GRADUALLY WEAKENS/DRIFTS E.
BEGINNING SUN...MID/UPPER TROF WILL BEGIN TO SHIFT E...RESULTING IN
SLOWLY RISING HEIGHTS. AT THE LOWER LEVELS...THE UPPER LAKES WILL
REMAIN FIRMLY IN THE THERMAL TROF WITH MODERATION ONLY APPEARING TO
OCCUR DUE TO DAYTIME HEATING. WITH MORNING 850MB TEMPS OF -1 TO -4C
ONLY RISING TO 0 TO -2 BY THE END OF THE AFTN...LAKE EFFECT -SHRA
WILL CONTINUE THRU THE DAY. HOWEVER...RISING HEIGHTS ALONG WITH
ADVECTION OF DRIER AIR AT THE LOW LEVELS AS WINDS BACK MORE W SHOULD
SPELL DIMINISHING SHRA FROM W TO E THRU THE DAY. BEING VERY EARLY IN
THE LAKE EFFECT SEASON...DIURNAL HEATING WILL ALSO DISRUPT LAKE
EFFECT PROCESSES...AIDING THE DIMINISHING TREND. SO...EXPECT
LINGERING NW FLOW LAKE EFFECT SHRA OVER THE W TO END BY EARLY/MID
AFTN. OVER THE E...LAKE EFFECT SHRA WILL DECREASE IN COVERAGE...BUT
NOT LIKELY END UNTIL LATER SUN EVENING WHEN WINDS BACK TO AN
OFFSHORE DIRECTION. WITH DIURNAL MIN SUN MORNING...1000-850MB
THICKNESS BTWN 1305-1310M OVER THE W SUGGEST SOME POTENTIAL FOR SNOW
FLAKES TO MIX WITH THE SHRA OVER THE HIGH TERRAIN. OTHERWISE...
GRAUPEL WILL CONTINUE TO BE THE MAIN FROZEN PTYPE THAT WILL MIX WITH
THE HEAVIER SHRA.
WAA REGIME RAMPS UP ON WESTERLY WINDS SUN NIGHT/MON AHEAD OF THE
NEXT SHORTWAVE TROF WHICH WILL BE DROPPING TOWARD THE UPPER LAKES.
WITH DEPARTURE OF LAKE EFFECT CLOUDS AND BEFORE HIGH CLOUDS ARRIVE
AHEAD OF APPRAOCHING SHORTWAVE AND BEFORE LOW-LEVEL WINDS INCREASE
SUBSTANTIALLY...TEMPS WILL HAVE AN OPPORTUNITY TO FALL QUICKLY UNDER
DRY AIR MASS (PRECIPITABLE WATER 50-60PCT OF NORMAL). FAVORED THE
LOWER SIDE OF GUIDANCE GIVEN THE COOL AFTN SUN. TEMPS WILL PROBABLY
SLIP BLO FREEZING IN MANY INTERIOR LOCATIONS. TIGHT PRES GRADIENT
BTWN SFC HIGH OVER THE OHIO VALLEY AND COLD FRONT DROPPING TOWARD
THE AREA MON WILL LEAD TO A BREEZY/WINDY DAY. 850MB WINDS ARE
PROGGED AT 40-45KT (TO NEAR 50KT ON NAM). EXAMINATION OF FCST
SOUNDINGS SUGGEST MIXED LAYER WILL BUILD SUFFICIENTLY TO TAP SOME OF
THE STRONGER WINDS. GUSTS OF 30-35MPH WILL PROBABLY BE COMMON...BUT
IF THE DAY ENDS UP WITH LESS CLOUDINESS/HIGHER MIXING HEIGHT...COULD
BE TALKING A WIND ADVY TYPE DAY. GIVEN THE DRY ANTECEDENT AIR MASS
AND LACK OF A LOW-LEVEL MOISTURE CONNECTION...SHRA SEEM UNLIKELY
AHEAD OF COLD FRONT. FOR NOW...PLAN TO STAY WITH JUST SLIGHT CHC
POPS OVER THE ERN FCST AREA...CLOSER TO STRONGER DEEP LAYER FORCING.
MAY END UP WITH JUST SOME SPRINKLES IF ANY PCPN DOES OCCUR.
LOW-LEVEL JET TRANSLATING ACROSS THE AREA WILL BRING STRONG WARMING
AS 850MB TEMPS SURGE TO 6-9C BY THE END OF THE AFTN. 60S SHOULD
GENERALLY BE THE RULE FOR MAX TEMPS.
COLD FRONT DROPS THRU THE AREA MON NIGHT. NOT EXPECTING MUCH IF ANY
LAKE EFFECT PCPN BEHIND FRONT UNDER MARGINALLY COLD AIR MASS AS
ANTICYCLONIC FLOW QUICKLY TAKES OVER AFTER FROPA. UNDER N WINDS...
MIGHT SEE A FEW -SHRA IN THE UPSLOPE AREAS NEAR LAKE SUPERIOR MON
NIGHT. DRY WEATHER SHOULD THEN DOMINATE TUE THRU THU AS SFC HIGH
PRES SLOWLY MOVES ACROSS THE UPPER GREAT LAKES. ONE EXCEPTION MAY BE
TUE NIGHT. 850MB TEMPS FALLING TO AROUND -2C MAY ALLOW SOME LAKE
EFFECT -SHRA TO DEVELOP. IN THE INTERIOR...SHOULD SEE A COUPLE OF
COLD NIGHTS (FREEZES) TUE NIGHT/WED NIGHT AS WINDS DIMINISH TO LIGHT
WITH SFC HIGH IN THE VCNTY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 138 PM EDT SAT SEP 22 2012
GRADUALLY LOWERING CIGS TO MVFR VALUES ARE EXPECTED DURING THE REST
OF THE TAF PERIOD. THIS IS DUE TO ADDITIONAL MOISTURE AND FORCING
ASSOCIATED WITH A SHORTWAVE WHICH WILL HELP ENHANCE LAKE EFFECT SHOWERS
OFF LAKE SUPERIOR LATE THIS AFTERNOON AND EVENING. WITH THE LONGEST
FETCH AND BEST MOISTURE...EXPECT THE HEAVIEST SHOWERS TO OCCUR AT
KSAW AND EAST. CMX AND IWD WILL ALSO HAVE A GOOD CHANCE OF SHOWERS
HOWEVER DUE TO THE SHORTER FETCH EXPECT COVERAGE AND INTENSITY TO BE
MUCH LIGHTER. VISIBILITIES COULD ALSO DROP INTO THE MVFR CATEGORY AS
WELL...ESPECIALLY AT SAWYER WITH THE MORE INTENSE SHOWERS. WINDS WILL
BE FAIRLY GUSTY THROUGH THE EARLY EVENING HOURS BEFORE THE SURFACE
LOW BEGINS TO SHIFT FARTHER TO THE EAST. GUSTS COULD REACH AS HIGH AS
30 KNOTS AT CMX.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 525 AM EDT SAT SEP 22 2012
NORTH TO NORTHWEST GALES TO 35-40KTS ARE EXPECTED TODAY OVER THE
EASTERN HALF OF LAKE SUPERIOR AND CONTINUE INTO TONIGHT. AS HIGH
PRESSURE OVER THE NORTHERN PLAINS BEGINS TO WORK IN TONIGHT...EXPECT
THE WINDS TO SLOWLY DIMINISH. THERE IS A POTENTIAL FOR WATERSPOUTS
TODAY AND TONIGHT...ALTHOUGH THE BEST CHANCE WILL COME TONIGHT AS
THE WINDS DECREASE SOME. A SECONDARY TROUGH DROPPING SOUTHEAST
ACROSS LAKE SUPERIOR MONDAY NIGHT WILL BRING ANOTHER PERIOD OF
GALES. SOUTHWEST WINDS AHEAD OF THIS FRONT SHOULD REACH GALES TO
35KTS BY LATE SUNDAY NIGHT AND CONTINUE INTO MONDAY UNTIL THE TROUGH
MOVES THROUGH. BEHIND THE TROUGH...HIGH PRESSURE WILL SETTLE OVER
THE UPPER GREAT LAKES REGION FOR TUESDAY AND WEDNESDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING UNTIL 11 PM EDT THIS EVENING FOR LSZ251-267.
GALE WARNING UNTIL 1 AM EDT SUNDAY FOR LSZ244-245-248>250-
264>266.
GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LSZ263.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...SRF
LONG TERM...ROLFSON
AVIATION...KEC
MARINE...SRF
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
357 PM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL PASS EAST OF THE AREA TONIGHT...WITH MUCH
COOLER AND DRIER AIR OVERSPREADING THE STATE OVERNIGHT AND SUNDAY.
A LARGE AREA OF HIGH PRESSURE WILL BUILD INTO THE COMMONWEALTH
FOR THE FIRST HALF OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SFC COLD FRONT EXTENDS FROM NEAR KIPT TO BETWEEN KJST AND KAOO AT
THIS HOUR. FRACTURED BANDS OF SHOWERS WITH LIGHT QPF HAVE TRACKED
ACROSS MY WESTERN AND NORTHERN COUNTIES...AND NOW APPEAR TO BE
SOLIDIFYING EAST OF THE CENTRAL MOUNTAINS AS HIGH RESOLUTION
MODELS HAVE BEEN SUGGESTING. HRRR SUGGESTS THE LINE WILL RAPIDLY
PUSH EAST OF MY CWA THIS EVENING WITH COOLER AND BREEZY
CONDITIONS IN ITS WAKE FOR TONIGHT. ISOLATED SVR IS A POSSIBILITY
BUT APPEARS TO BE AN OUTLIER AT THIS POINT.
MINS TONIGHT WILL BE MUCH COOLER RANGING FROM THE LOWER 40S UP
NORTH TO THE LOWER 50S ACROSS THE SOUTHEAST. FAIRLY BREEZY
CONDITIONS THIS EVENING WILL SLACKEN OVERNIGHT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
COOL POST-FRONTAL WEATHER REGIME IN FULL EFFECT ON SUNDAY...AS A
SPRAWLING UPPER LOW EXTENDING FROM THE NORTHERN GREAT LAKES TO
HUDSON BAY LIFTS SLOWLY NORTHEASTWARD.
AFTERNOON TEMPERATURES WILL BE 6 TO 10 DEG F BELOW NORMAL AS THE
MEAN UPPER TROF PERSISTS OVER EASTERN CANADA KEEPING CHILLY AIR
OVER THE GREAT LAKES AND NORTHEAST. HIGHS WILL VARY FROM THE LOWER
TO MID 50S ACROSS THE NW MTNS AND LAURELS...TO THE MID 60S
THROUGHOUT MUCH OF THE SUSQ VALLEY. IT WILL BE CLOUDY FOR MUCH
OF WESTERN AND NORTHERN PA...WITH A CHC OF SHOWERS EXTENDING INTO
THE CENTRAL MOUNTAINS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
DEEP LONGWAVE TROF CENTERED OVER ONTARIO TODAY IS FORECAST TO
SLOWLY MIGRATE EASTWARD THROUGH NEXT WEEK. THE CORE OF LOWER
HEIGHTS HOWEVER IS FORECAST TO LIFT INTO NRN QUEBEC BY
MIDWEEK...KEEPING PA MAINLY IN A COOL WRLY/ZONAL FLOW ON THE SRN
END OF THE UPPER LOW. SEVERAL CHANCES SHOULD EXIST FOR GENERALLY
WEAK SHORTWAVES TO MOVE THROUGH THE FLOW AND BRING THE CHANCE OF
SHOWERS...HOWEVER MOST OF THE PERIOD WILL BE DRY.
CLOUDS SHOULD DISSIPATE IN MOST LOCATIONS...AND RETREAT TO COVER
MAINLY THE WESTERN MTNS SUNDAY NIGHT...WHICH WILL SET THE STAGE FOR
A VERY COOL...AND LIKELY FROSTY NIGHT ACROSS THE NORTH. WILL NOTE
THE POTENTIAL OF SCATTERED FROST IN THE HWOCTP ACROSS THE NRN MTNS
AND LAURELS /SHOULD CLOUD AND WIND DISSIPATE ENOUGH/.
LOWS AROUND DAYBREAK MONDAY WILL RANGE FROM THE MID 30S ACROSS THE
NRN MTNS TO THE UPPER 30S AND MID 40S ELSEWHERE.
LATEST MODEL AND ENSEMBLE GUIDANCE CONTINUES TO SHOW ANOTHER FAIRLY
VIGOROUS UPPER TROF CROSSING THE REGION SUNDAY NIGHT AND MONDAY...
BRINGING CONTINUED COOL TEMPS AND ANOTHER PERIOD OF SCATTERED
SHOWERS.
A ZONAL FLOW DEVELOPS LATER MONDAY AND TUESDAY WITH MODERATING 850
MB TEMPERATURES AND HIGH PRESSURE BUILDS ENE FROM THE CENTRAL
TENNESSEE RIVER VALLEY. TEMPS WILL MODERATE FURTHER ON WEDNESDAY
AHEAD OF A FRONTAL SYSTEM DROPPING SOUTHWARD FROM THE GREAT LAKES.
THE FRONT SHOULD SAG AND STALL SOUTH OF THE MASON DIXON LINE LATE
THIS WEEK...WITH COOLER AN DRIER WEATHER TO THE NORTH INTO NEXT
WEEKEND.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
MVFR CIGS AND VSBYS IN SHOWERS AND POSSIBLY TSRA THIS AFTERNOON
AND EVENING AS A COLD FRONT PUSHES EASTWARD. ISOLATED STRONG
STORMS POSSIBLE OVER EXTREME EASTERN PA BEFORE THE FRONT PASSES.
DRY SLOT AND COOLER AIR WORKS IN OVERNIGHT THROUGH SUNDAY.
COLD AIR ALOFT WILL LIKELY TRIGGER SOME SHOWERS LATE SUNDAY...
PERHAPS INTO MONDAY MORNING. AS THE HIGH MOVES EAST AND SOUTH OF
THE AREA LATE MONDAY INTO TUE. A WARMER SW FLOW OF AIR WILL SET IN
FOR MID WEEK.
OUTLOOK...
SUN...MAINLY VFR BUT MVFR CONDITIONS POSSIBLE ACROSS THE HIGHER
MTNS WITH A FEW SHOWERS.
MON...BECOMING VFR...AS HIGH PRESSURE BUILDS ACROSS THE AREA.
TUE-WED...VFR...WITH A FEW SHOWERS POSS LATER TUES INTO WED
ACROSS WESTERN MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...DEVOIR/LAMBERT
SHORT TERM...DEVOIR/LAMBERT
LONG TERM...LAMBERT/GARTNER
AVIATION...DEVOIR/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
252 PM EDT SAT SEP 22 2012
.SYNOPSIS...
A COLD FRONT WILL PASS EAST OF THE AREA TONIGHT...WITH MUCH
COOLER AND DRIER AIR OVERSPREADING THE STATE OVERNIGHT AND SUNDAY.
A LARGE AREA OF HIGH PRESSURE WILL BUILD INTO THE COMMONWEALTH
FOR THE FIRST HALF OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
SFC COLD FRONT EXTENDS FROM NEAR KIPT TO BETWEEN KJST AND KAOO AT
THIS HOUR. FRACTURED BANDS OF SHOWERS WITH LIGHT QPF HAVE TRACKED
ACROSS MY WESTERN AND NORTHERN COUNTIES...AND NOW APPEAR TO BE
SOLIDIFYING EAST OF THE CENTRAL MOUNTAINS AS HIGH RESOLUTION
MODELS HAVE BEEN SUGGESTING. HRRR SUGGESTS THE LINE WILL RAPIDLY
PUSH EAST OF MY CWA THIS EVENING WITH COOLER AND BREEZY
CONDITIONS IN ITS WAKE FOR TONIGHT. ISOLATED SVR IS A POSSIBILITY
BUT APPEARS TO BE AN OUTLIER AT THIS POINT.
MINS TONIGHT WILL BE MUCH COOLER RANGING FROM THE LOWER 40S UP
NORTH TO THE LOWER 50S ACROSS THE SOUTHEAST. FAIRLY BREEZY
CONDITIONS THIS EVENING WILL SLACKEN OVERNIGHT.
&&
.SHORT TERM /SUNDAY/...
COOL POST-FRONTAL WEATHER REGIME IN FULL EFFECT ON SUNDAY...AS A
SPRAWLING UPPER LOW EXTENDING FROM THE NORTHERN GREAT LAKES TO
HUDSON BAY LIFTS SLOWLY NORTHEASTWARD.
AFTERNOON TEMPERATURES WILL BE 6 TO 10 DEG F BELOW NORMAL AS THE
MEAN UPPER TROF PERSISTS OVER EASTERN CANADA KEEPING CHILLY AIR
OVER THE GREAT LAKES AND NORTHEAST. HIGHS WILL VARY FROM THE LOWER
TO MID 50S ACROSS THE NW MTNS AND LAURELS...TO THE MID 60S
THROUGHOUT MUCH OF THE SUSQ VALLEY. IT WILL BE CLOUDY FOR MUCH
OF WESTERN AND NORTHERN PA...WITH A CHC OF SHOWERS EXTENDING INTO
THE CENTRAL MOUNTAINS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
CLOUDS SHOULD DISSIPATE IN MOST LOCATIONS...AND RETREAT TO COVER
MAINLY THE WESTERN MTNS SUNDAY NIGHT...WHICH WILL SET THE STAGE FOR
A VERY COOL...AND LIKELY FROSTY NIGHT ACROSS THE NORTH. WILL NOTE
THE POTENTIAL OF SCATTERED FROST IN THE HWOCTP ACROSS THE NRN MTNS
AND LAURELS /SHOULD CLOUD AND WIND DISSIPATE ENOUGH/.
LOWS AROUND DAYBREAK MONDAY WILL RANGE FROM THE MID 30S ACROSS THE
NRN MTNS TO THE UPPER 30S AND MID 40S ELSEWHERE.
LATEST MODEL AND ENSEMBLE GUIDANCE CONTINUES TO SHOW ANOTHER FAIRLY
VIGOROUS UPPER TROF CROSSING THE REGION SUNDAY NIGHT AND MONDAY...
BRINGING CONTINUED COOL TEMPS AND ANOTHER PERIOD OF SCATTERED
SHOWERS.
A ZONAL FLOW DEVELOPS LATER MONDAY AND TUESDAY WITH MODERATING 850
MB TEMPERATURES AND HIGH PRESSURE BUILDS ENE FROM THE CENTRAL
TENNESSEE RIVER VALLEY. TEMPS WILL MODERATE FURTHER ON WEDNESDAY
AHEAD OF A FRONTAL SYSTEM DROPPING SOUTHWARD FROM THE GREAT LAKES.
THE FRONT SHOULD SAG AND STALL SOUTH OF THE MASON DIXON LINE LATE
THIS WEEK...WITH COOLER AN DRIER WEATHER TO THE NORTH.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
MVFR CIGS AND VSBYS IN SHOWERS AND POSSIBLY TSRA THIS AFTERNOON
AND EVENING AS A COLD FRONT PUSHES EASTWARD. ISOLATED STRONG
STORMS POSSIBLE OVER EXTREME EASTERN PA BEFORE THE FRONT PASSES.
DRY SLOT AND COOLER AIR WORKS IN OVERNIGHT THROUGH SUNDAY.
COLD AIR ALOFT WILL LIKELY TRIGGER SOME SHOWERS LATE SUNDAY...
PERHAPS INTO MONDAY MORNING. AS THE HIGH MOVES EAST AND SOUTH OF
THE AREA LATE MONDAY INTO TUE. A WARMER SW FLOW OF AIR WILL SET IN
FOR MID WEEK.
OUTLOOK...
SUN...MAINLY VFR BUT MVFR CONDITIONS POSSIBLE ACROSS THE HIGHER
MTNS WITH A FEW SHOWERS.
MON...BECOMING VFR...AS HIGH PRESSURE BUILDS ACROSS THE AREA.
TUE-WED...VFR...WITH A FEW SHOWERS POSS LATER TUES INTO WED
ACROSS WESTERN MTNS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR
SHORT TERM...DEVOIR
LONG TERM...LAMBERT
AVIATION...DEVOIR/CERU