May 20, 2012 Forecast Discussion

000
FXUS61 KALY 201133
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
732 AM EDT SUN MAY 20 2012

.SYNOPSIS…
HIGH PRESSURE WILL DOMINATE OUR WEATHER FOR ONE MORE DAY WITH
SUMMER LIKE CONDITIONS TODAY. LOW PRESSURE OFF THE ATLANTIC
SEABOARD WILL PUSH INCREASING MOISTURE AND CLOUDS INTO THE REGION
TO START THE WEEK…WITH UNSETTLED WEATHER AND THE THREAT OF
SHOWERS AND THUNDERSTORMS THROUGH WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
AS OF 630 AM EDT…MAINLY CLEAR SKIES AND MILD TEMPS FOR THE
MIDDLE OF MAY PREVAILED ACRS THE FA WITH TEMPS IN THE MID 40S TO
MID 50S.

FOR TODAY…EXPECT GENERALLY MOSTLY SUNNY TO SUNNY CONDITIONS AND
WARM TEMPERATURES WITH HIGHS GENERALLY IN THE UPPER 70S TO UPPER 80S.
H8 TEMPS REACH 12 TO 15 C AND WITH DEEP MIXING TODAY EXPECT TEMPS
TO GENERALLY BE AROUND 5 DEGREES WARMER THAN SATURDAY. THE
EXCEPTION WITH BE ACRS THE SE PTN OF FA WHERE HIGH CLOUDS WILL
MOVE IN AND BECOME THICKER AHEAD OF A COASTAL LOW NEAR THE
VIRGINA/NORTH CAROLINA BORDER. THESE CLOUDS WILL KEEP HIGHS IN
THIS AREA AROUND 80.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/…
TONIGHT…EXPECT MAINLY CLEAR SKIES WILL GIVE WAY TO INCREASING
CLOUDS FROM SOUTHEAST TO NORTHWEST AS A WEAK AREA OF LOW PRESSURE
MOVES NORTHWEST INTO VIRGINIA. WHILE EXPECT THAT MOST OF FA WILL
REMAIN DRY OVERNIGHT…SOME RAIN MAY REACH FAR SOUTHERN PTN OF
BY MONDAY MORNING SO HAVE SLIGHT CHANCE TO LOW CHANCE POPS IN THIS
AREA LATE TONIGHT. EXPECT LOWS IN THE MID 40S TO MID 50S.

THE PERIOD FROM MONDAY THROUGH TUESDAY NIGHT REMAINS VERY
UNCERTAIN AS MODELS ARE HAVING A DIFFICULT TIME WHERE SURFACE
SYSTEMS WILL TRACK AS WELL AS PLACEMENT OF UPPER TROF. THE GEM AND
NAM HAVE VERY LITTLE PCPN ACRS FA THROUGH 00Z TUESDAY…WHILE THE
GFS AND ECMWF CONFINE PCPN MAINLY TO THE SRN HALF OF FA. BY MONDAY
EVENING THE MODELS HAVE A VERY COMPLEX SETUP ACROSS THE NORTHEAST
WITH A SECOND LOW PRESSURE SYSTEM WELL EAST OF DELMARVA…THE MAIN
LOW OVER EITHER VA OR WVA…A COASTAL FRONT ALONG THE SOUTHERN NEW
ENGLAND COAST AND A COLD FRONT MOVING INTO THE EASTERN GREAT
LAKES. EXPECT THAT THERE WILL BE SCATTERED SHOWERS WITH A CHANCE
FOR THUNDERSTORMS MONDAY AFTERNOON INTO MONDAY EVENING AND AGAIN
TUESDAY AFTERNOON INTO TUESDAY EVENING AS MLMUCAPES REACH AT LEAST
SEVERAL HUNDRED J/KG AND MAY BE EVEN GREATER IF MORE HEATING
OCCURS DESTABILIZING THE ATMOSPHERE FURTHER. SHOWALTER INDICES
ALSO DROP TO AROUND ZERO BOTH AFTERNOONS. PWATS ALSO RISE TO BTWN
1.25 AND 1.50 INCH AND WITH LITTLE WIND FLOW ALOFT EXPECT THAT
THESE THUNDERSTORMS WILL BE SLOW MOVERS AND HAVE AT THE POTENTIAL
TO PRODUCE SOME LOCALLY HEAVY DOWNPOURS. SINCE ANY HYDROLOGIC
ISSUES ARE EXPECTED TO BE ISOLATED WILL LEAVE OUT OF HWO AT THIS
TIMES AND JUST MENTION CHANCE OF NON-SEVERE THUNDERSTORMS EACH
AFTERNOON AND EVENING MONDAY THROUGH WEDNESDAY. EXPECT HIGHS
MONDAY AND TUESDAY TO GENERALLY BE IN THE UPPER 60S TO UPPER 70S
WITH LOWS MONDAY NIGHT IN THE MID 50S TO AROUND 60 AND TUESDAY
NIGHT IN THE UPPER 40S TO UPPER 50S.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/…
WED-THU…MODEL UNCERTAINTY RATHER HIGH DURING THIS PERIOD…WITH
THE MAIN DILEMMA REGARDING THE HANDLING OF MID/UPPER LEVEL ENERGY
MIGRATING E/NE FROM THE TENNESSEE VALLEY/SOUTHERN APPALACHIANS. THE
00Z/20 GFS SEEMS A BIT MORE PROGRESSIVE WITH THIS FEATURE…WHILE
THE ECMWF IS A BIT SLOWER. FOR NOW…WILL INDICATE CHC POPS FOR
WED/WED NT…FOR SCATTERED SHOWERS/TSTMS…THEN LIMIT POPS TO
SOUTHERN AREAS FOR THU…MAINLY IN THE SLIGHT CHC RANGE. IT SHOULD
REMAIN SOMEWHAT HUMID DURING THIS TIME PERIOD…WITH DAYTIME MAXES
GENERALLY 75-80 IN VALLEYS…AND 70-75 ACROSS HIGHER
ELEVATIONS…WITH OVERNIGHT MINS 55-60 IN VALLEYS…AND UPPER 40S TO
LOWER 50S ACROSS HIGHER ELEVATIONS.

THU NT-SAT…MODEL UNCERTAINTY REMAINS SOMEWHAT HIGH…MAINLY WITH
REGARD TO TIMING OF FEATURES…WITH THE GFS INDICATING A NORTHERN
STREAM SHORTWAVE PASSING NORTH OF THE REGION LATE FRIDAY…ALONG
WITH AN ATTENDANT COLD FRONT SWEEPING THROUGH THE REGION…FOLLOWED
BY HIGH PRESSURE AND COOLER…LESS HUMID CONDITIONS BY SATURDAY. THE
ECMWF…ON THE OTHER HAND…IS A BIT SLOWER…WITH POSSIBLE FRONTAL
PASSAGE DELAYED UNTIL LATE FRI NT OR SAT. EITHER WAY…BOTH MODELS
ARE SIGNALING THAT THE BRUNT OF THE UPPER LEVEL RIDGING AND
ASSOCIATED ANOMALOUS WARMTH MAY BE SHUNTED SOUTH AND WEST OF THE
REGION DURING AND AFTER THIS TIME PERIOD. HAVE SIDED A BIT CLOSER TO
THE ECMWF SOLUTION…AND WILL INDICATE SLIGHT CHC POPS FOR SAT WITH
POSSIBLE FROPA…WITH GENERALLY FAIR CONDITIONS FRIDAY. EXPECT WARM
TEMPS TO CONTINUE…WITH MAXES REACHING AROUND 80 IN VALLEYS…AND
LOWER/MID 70S ACROSS HIGHER ELEVATIONS FRI…THEN WARMING INTO THE
LOWER/MID 80S SAT IN VALLEYS…AND 75-80 ACROSS HIGHER ELEVATIONS.
OVERNIGHT MINS SHOULD RANGE FROM 55-60 IN VALLEYS…AND 50-55 ACROSS
HIGHER ELEVATIONS.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/…
MAINLY VFR CONDITIONS ARE EXPECTED THROUGH 12Z/MONDAY.
OTHERWISE…JUST OCCASIONAL HIGH CLOUDS AT TIMES DURING
SUNDAY…ALONG WITH PERHAPS SOME CUMULUS CLOUDS DOTTING THE SKY.

THERE IS A SLIGHT CHANCE FOR PATCHY GROUND FOG DEVELOPMENT ONCE
AGAIN LATE TONIGHT…MAINLY AT KGFL…WHICH COULD PRODUCE
OCCASIONAL…BRIEF REDUCTIONS IN VSBY INTO THE MVFR/IFR RANGE.
CONFIDENCE TOO LOW AT THIS TIME TO INCLUDE ANY MENTION IN CURRENT
ISSUANCE OF TAFS.

TOWARD DAYBREAK MONDAY…SOME LOWER CLOUDS ARE EXPECTED TO SPREAD
NORTHWEST…REACHING KPOU…AND POSSIBLY KPSF PRIOR TO 12Z/MON. CIGS
SHOULD BE VFR…BUT THERE IS A SLIGHT CHANCE THEY COULD BE HIGH END
MVFR.

LIGHT/VARIABLE WINDS WILL BECOME SOUTHEAST BY LATE MORNING…AT 5-10
KT. WINDS WILL THEN BECOME LIGHT/VARIABLE AGAIN AFTER SUNSET.

.OUTLOOK…
SUN NT…VFR. NO SIG WX.
MON-WED…VFR/MVFR. CHC -SHRA/-TSRA.
THU…VFR. SLIGHT CHC -SHRA AT KPOU.

&&

.FIRE WEATHER…
HIGH PRESSURE WILL DOMINATE OUR WEATHER FOR ONE MORE DAY WITH
SUMMER LIKE CONDITIONS TODAY. LOW PRESSURE OFF THE ATLANTIC
SEABOARD WILL PUSH INCREASING MOISTURE AND CLOUDS INTO THE REGION
TO START THE WEEK…WITH UNSETTLED WEATHER AND THE THREAT OF
SHOWERS AND THUNDERSTORMS THROUGH WEDNESDAY.

THE RELATIVE HUMIDITY WILL DROP TO 25 TO 35 PERCENT THIS
AFTERNOON…RECOVER TO 70 TO 95 PERCENT TONIGHT….AND ONLY DROP TO
40 TO 75 PERCENT ON MONDAY.

DEW FORMATION IS LIKELY SUNDAY NIGHT OVER NORTHERN AREAS.
SOUTHERN AREAS COULD SEE SOME LIGHT RAIN AFTER DAYBREAK MONDAY.

WINDS WILL BE SOUTH TO SOUTHEAST AT 5 TO 10 MPH THROUGH MONDAY.

&&

.HYDROLOGY…
NO HYDROLOGIC ISSUES EXPECTED THROUGH TONIGHT WITH DRY WEATHER
CONTINUING. A SLOW MOVING UPPER LEVEL LOW PRESSURE SYSTEM WILL
BRING SOME SHOWERS AND THUNDERSTORMS TO OUR REGION THROUGH THE MID
WEEK PERIOD WITH THE BEST CHANCE FOR THUNDERSTORMS BEING DURING
THE AFTERNOON AND EVENING HOURS MONDAY THROUGH WEDNESDAY. ALTHOUGH
WIDESPREAD HEAVY RAIN IS NOT FORECAST…SOME ISOLATED HYDROLOGIC
ISSUES WILL BE POSSIBLE DUE TO LOCALLY HEAVY RAIN FROM SLOW MOVING
THUNDERSTORMS.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…NONE.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…11/SNYDER
NEAR TERM…11
SHORT TERM…11
LONG TERM…KL
AVIATION…KL/NAS
FIRE WEATHER…11
HYDROLOGY…SND/11

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