Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 260324 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1024 PM EST WED FEB 25 2015 .SYNOPSIS...
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A WEAK COLD FRONT WILL PASS TONIGHT. LOW PRESSURE WILL TRACK EAST OF THE REGION THURSDAY AND THURSDAY NIGHT. CANADIAN HIGH PRESSURE THEN BUILDS INTO THE AREA THROUGH SATURDAY...THEN SLIDES OFFSHORE FROM SATURDAY NIGHT INTO SUNDAY. A COLD FRONT APPROACHES FROM THE NORTHWEST LATE SUNDAY...THEN CROSSES THE AREA SUNDAY NIGHT AND EARLY MONDAY...WITH WAVES OF LOW PRESSURE RIDING ALONG THE FRONT. HIGH PRESSURE BUILDS IN BEHIND THE FRONT INTO TUESDAY. ANOTHER STORM SYSTEM IMPACTS THE AREA TUESDAY NIGHT AND WEDNESDAY.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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A WEAK COLD FRONT WILL SWING THROUGH BY MIDNIGHT WITH WINDS SHIFTING TO THE N. MID AND HIGH CLOUDS THICKEN OVERNIGHT. ANY LIGHT SNOW OR FLURRIES WITH SOUTHERN SYSTEM SHOULD HOLD OFF UNTIL AFTER DAYBREAK.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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SPC SSEO INDICATING A SHARP CUTOFF IN PROB OF 1 INCH OF SNOW JUST SOUTH OF LI AND ONLY 20-30 PERCENT CHANCE ACROSS SE LI. 12Z GEFS/CMCE/SREF ENSEMBLE PROBS OF GREATER THAN .05 INCHES IN 6 HRS ARE GENERALLY IN THE 30-50 PERCENT RANGE FOR E LI AND SE CT...TAPERING TO LESS THAN 20 PERCENT CHANCE FOR FAR NW OF NYC. WITH GOOD HIGH RES/OPER AGREEMENT HAVE ADJUSTED POPS TO SHOW GREATEST POTENTIAL FOR LIGHT SNOW AFTER DAYBREAK INTO EARLY AFTERNOON. NO CHANGES TO POPS FOR A VERY LIGHT SNOW EVENT ON THU AT THIS TIME. WILL ALLOW NIGHT SHIFT TO EVALUATE RADAR AND HIGH- RES TRENDS TO ADJUST POPS. LOW PRES IN THE VICINITY OF CAPE HATTERAS THU MORNING...TRACKS TO THE ENE THROUGH THE DAY AND REACHES A POINT ABOUT 625 MILES E OF NYC 00Z FRI. AT THE SAME TIME...A WEAK SHORTWAVE ENERGY APPROACHES THE REGION. EXPECT THESE TWO FEATURES TO PRODUCE SOME LGT SNOW OR FLURRIES DURING THE DAY. THERE APPEARS TO BE SOME CORRELATION WITH THE SLOWER SOLUTIONS BRINGING THE PRECIPITATION SHIELD ASSOCIATED WITH THE LOW CLOSER TO THE COAST. THE SREF AND ECMWF ARE IN THE WET CAMP...WITH THE NAM AND GFS MAINLY DRY. HAVE SIDED CLOSER TO THE CONSISTENT NAM AND GFS WITH RESPECT TO TO SNOW AMOUNTS...BUT INCREASED POPS TO LIKELY MOST AREAS BASED ON HIGHER CONFIDENCE IN AT LEAST SOME LIGHT PRECIPITATION BASED ON THE ECMWF AND SREF TRENDS. SNOW CHANCES WIND DOWN THU EVE...BUT IT SHOULD REMAIN MOSTLY CLOUDY AS A WAVE OF MID LEVEL MOISTURE SWINGS THROUGH. CANNOT RULE OUT A FLURRY. THE CANOPY OF CLOUDS WILL REDUCE RADIATIONAL COOLING POTENTIAL...BUT IT WILL STILL BE FRIGID WITH THE ARCTIC AIR MASS IN PLACE. TEMPS ON THU A BLEND OF THE ECMWF AND NAM 2M DATA. A MET/MAV BLEND WAS USED THU NIGHT.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/... EVEN WITH PASSAGE OF 700-500 HPA SHORTWAVES FRIDAY AND FRIDAY NIGHT...VERY DRY LOW LEVELS WILL KEEP THINGS DRY. HIGHS FRIDAY SHOULD RUN AROUND 15-20 DEGREES BELOW NORMAL...CONSISTENT WITH A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 900 HPA PER BUFKIT SOUNDINGS. LOWS FRIDAY NIGHT SHOULD RUN AROUND 20-25 DEGREES BELOW NORMAL - BASED ON AN ADJUSTED BLEND OF MAV/MET GUIDANCE WITH NAM AND GFS 2-METER TEMPERATURES. WIND CHILLS SHOULD BE MAINLY IN THE NEGATIVE SINGLE DIGITS. LOW-MID LEVEL SHORTWAVE RIDGING PASSING OVER THE AREA SATURDAY WILL KEEP THINGS DRY. HIGHS SATURDAY WERE BASED ON A BLEND OF ALL AVAILABLE GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 975-950 HPA PER BUFKIT SOUNDINGS - AND SHOULD BE AROUND 20 DEGREES BELOW NORMAL. SATURDAY NIGHT SHOULD BE DRY WITH EITHER WEAK SHORTWAVE RIDGING OR A BRIEF PERIOD OF ZONAL FLOW OVER THE AREA DEPENDING ON YOUR MODEL/MODEL BLEND OF CHOICE. MODELS ARE THEN IN GENERAL AGREEMENT THAT A NORTHERN STREAM TROUGH TRACKS FROM THE MIDWEST SUNDAY EVENING...TO EAST OF MAINE BY LATE MONDAY (ECMWF A TAD FASTER THAN THE GFS)...WITH A SURFACE LOW FORECAST TO DEVELOP OVER THE GULF OF MAINE/NOVA SCOTIA ON MONDAY. MAINLY WARM ADVECTION PRECIPITATION FOR THE AREA AHEAD OF THE ASSOCIATED SURFACE COLD FRONT...THEN BEHIND IT DUE TO THE FORECAST ANAFRONTAL NATURE OF THE SYSTEM FROM LATE SUNDAY INTO MONDAY. SHOULD MAINLY SEE ALL SNOW...WITH POSSIBLY A WINTRY MIX TO START ACROSS INTERIOR ZONES...AND A WINTRY MIX TRANSITIONING TO ALL SNOW OVER COASTAL ZONES. NOTE...FOR SIMPLICITY AND DUE TO THE INHERENT UNCERTAINTY IN THIS TIME FRAME HAVE RESTRICTED P-TYPES TO RAIN/RAIN-SNOW/SNOW. ALSO...IF PRECIPITATION LINGERS INTO MONDAY AFTERNOON OVER EASTERN ZONES...THEN THE BOUNDARY LAYER COULD WARM ENOUGH TO CHANGE THINGS BACK TO RAIN BEFORE ENDING. DRY MONDAY NIGHT UNDER NW FLOW ALOFT WITH NO SHORTWAVES CURRENTLY FORECAST TO BE EMBEDDED IN THE MEAN FLOW. MODEL DIFFERENCE FOR THE SYSTEM THAT COULD IMPACT THE AREA TUESDAY-WEDNESDAY. THE ECMWF KEEPS THE SURFACE WARM FRONT AND LOW TO THE S...WITH PRECIPITATION MAINLY CONFINED TO THE SW 1/2 OF THE CWA. THE GFS BRINGS THE PRIMARY LOW TO THE WEST...WITH A SECONDARY LOW DEVELOPING TO THE S OF LONG ISLAND. FOR NOW HAVE A CHANCE OF SNOW OVER WESTERN AREAS TUESDAY AFTERNOON (RAIN/SNOW NYC)...A CHANCE OF SNOW TUESDAY NIGHT AND THEN SNOW CHANGING TO RAIN ON WEDNESDAY EXCEPT OVER FAR N INTERIOR ZONES. ONCE AGAIN FOR SIMPLICITY AND INHERENT UNCERTAINTY IN THIS TIME RANGE HAVE NOT ADDRESSED SLEET OR FREEZING RAIN POTENTIAL AT THIS TIME. FOR TEMPERATURES SATURDAY NIGHT-WEDNESDAY FOLLOWED A BLEND OF ALL AVAILABLE GUIDANCE...WITH ECMWF 2-METER TEMPERATURES BLENDED IN TUESDAY NIGHT AND WEDNESDAY. TEMPERATURES ARE BELOW NORMAL SATURDAY NIGHT/SUNDAY...NEAR NORMAL SUNDAY NIGHT...THEN VARYING DEGREES OF BELOW NORMAL AGAIN FOR THE REMAINDER OF THE FORECAST PERIOD. && .AVIATION /03Z THURSDAY THROUGH MONDAY/...
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A COLD FRONT WILL MOVE ACROSS BY 04Z...FOLLOWED BY HIGH PRESSURE BUILDING TO THE NORTH OVERNIGHT. DEEPENING LOW PRESSURE WILL PASS WELL TO THE SE ON THU. HIGH CONFIDENCE IN VFR THROUGH TONIGHT...WITH LOWERING/THICKENING HIGH/MID LEVEL CLOUDS. THE CONFIDENCE IN FLIGHT CAT DURING THE DAYTIME HRS THU IS LOW...AS THE OFFSHORE LOW AND A PASSING UPPER LEVEL DISTURBANCE SHOULD COMBINE TO PRODUCE SOME LIGHT SNOW... WHICH MAY BRING PREVAILING MVFR CIGS AND OCNL IFR VSBY. FCST DOES NOT HIT THIS VERY HARD ATTM BUT IS TRENDING IN THAT DIRECTION. ...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: PREVAILING MVFR/BRIEF IFR CONDS POSSIBLE BETWEEN 15Z-20Z THU. KLGA FCSTER COMMENTS: MVFR CONDS POSSIBLE BETWEEN 15Z-20Z THU. KEWR FCSTER COMMENTS: MVFR CONDS POSSIBLE BETWEEN 15Z-20Z THU. KTEB FCSTER COMMENTS: MVFR CONDS POSSIBLE BETWEEN 15Z-20Z THU. KHPN FCSTER COMMENTS: MVFR CONDS POSSIBLE BETWEEN 15Z-20Z THU. KISP FCSTER COMMENTS: PREVAILING MVFR/BRIEF IFR CONDS POSSIBLE BETWEEN 15Z-21Z THU. .OUTLOOK FOR 00Z FRI THROUGH MON... .THU NIGHT-SUNDAY...VFR. .SUNDAY NIGHT-MON...MIXED PRECIPITATION WITH MVFR CONDITIONS.
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&& .MARINE...
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MARGINAL SCA CONDITIONS MAY RETURN ON THE OCEAN THU AS LOW PRES PASSES SE OF THE WATERS...WITH IMPROVEMENT THU NIGHT. WITH MARGINAL SCA POTENTIAL...HAVE HELD OFF ON SCA TO LET NEXT SHIFT EVALUATE TRENDS. SCA LEVEL SEAS COULD LINGER ON THE COASTAL OCEAN WATERS EAST OF MORICHES INLET FRIDAY NIGHT...OTHERWISE SUB-SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED ON ALL WATERS FROM FRIDAY NIGHT INTO SUNDAY. INCREASING SW WINDS COULD BUILD SEAS TO SCA LEVELS ON THE COASTAL OCEAN WATERS LATE SUNDAY. NW FLOW BEHIND A COLD FRONT COULD PRODUCE GUSTS TO SMALL CRAFT LEVELS ON ALL WATERS ON MONDAY.
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&& .HYDROLOGY... A FEW HUNDREDTHS OF LIQUID EQUIVALENT IS POSSIBLE THU. IT SHOULD BE DRY FROM FRIDAY INTO SUNDAY. THERE IS THE POTENTIAL FOR LIGHT TO POSSIBLY MODERATE LIQUID EQUIVALENT TO FALL FROM SUNDAY INTO MONDAY. AT THIS TIME NO SIGNIFICANT PRECIPITATION IS EXPECTED. ICE WILL CONTINUE TO DEVELOP ON LOCAL AREA RIVERS AND STREAMS AS TEMPS REMAIN WELL BELOW AVERAGE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JMC/MALOIT NEAR TERM...JMC SHORT TERM...JMC LONG TERM...MALOIT AVIATION...GOODMAN/DW MARINE...JMC/MALOIT HYDROLOGY...JMC/MALOIT

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