Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 252105 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 405 PM EST WED FEB 25 2015 .SYNOPSIS...
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AN ARCTIC FRONT WILL PASS THIS EVENING. 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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THE COLD FRONT WAS STILL N OF THE CWA THIS AFTERNOON. SOUTHWARD PROGRESS WAS SLOW AS IT WAS GENERALLY ALIGNED WITH THE UPPER FLOW. SUNSET ALONG WITH LOWERING PRES TO THE S SHOULD ALLOW THE SURFACE BOUNDARY TO SWING THROUGH THIS EVE WITH WINDS SHIFTING TO THE N. SOME CIRRUS TO START THE EVE...THEN MID AND HIGH CLOUDS THICKEN OVERNIGHT. TEMPS A BLEND OF GUIDANCE...BUT THE DIURNAL SWING MAY CREATE SOME ERRATIC HOURLY READINGS. FOR INSTANCE...SPOTS COULD DROP QUICKER THAN FORECAST AFT SUNSET...THEN STALL AFT MIDNIGHT.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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LOW PRES IN THE VICINITY OF CAPE HATTERAS 12Z THU...TRACKS TO THE ENE THROUGH THE DAY AND REACHES A POINT ABOUT 625 MILES E OF NYC 00Z FRI. AT THE SAME TIME...A SHORTWAVE CURRENTLY OVER IA 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 BAD ON HIGHER CONFIDENCE IN AT LEAST SOME 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 AIRMASS 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/...
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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 ANAFRONT 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.
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&& .AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
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A COLD FRONT WILL MOVE ACROSS THE REGION LATE THIS AFTERNOON...FOLLOWED BY HIGH PRESSURE TONIGHT. DEEPENING LOW PRESSURE PASSES SOUTH AND EAST OF THE AREA ON THU. HIGH CONFIDENCE IN VFR TROUGH TONIGHT. LOWERING MID LEVEL DECK TONIGHT INTO THU. W WINDS 10-15 KT WITH GUSTS AROUND 20 KT THIS AFT. WINDS THEN VEER NW-N DIMINISH TO UNDER 10 KT THIS EVENING...THEN N-NE 10-12 KT THU. THERE IS A CHANCE OF LIGHT SNOW ON THU...ESPECIALLY NEAR THE COAST WITH THE POTENTIAL FOR A PERIOD OF MVFR/IFR CONDITIONS. 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: NO UNSCHEDULED AMENDMENTS EXPECTED. KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KEWR FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 21Z THU THROUGH MONDAY... .THU AFT...CHANCE OF LIGHT SNOW WITH MVFR CONDITIONS. .FRI-SUN...VFR. .SUN NIGHT-MON...MIXED PRECIPITATION WITH MVFR CONDITIONS.
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&& .MARINE...
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SCA WINDS WILL DIMINISH ON THE OCEAN THIS EVE...SO THE SCA TIMING REMAINS THE SAME ENDING AT 6 PM. SCA CONDITIONS RETURN ON THE OCEAN THU AS LOW PRES PASSES SE OF THE WATERS...WITH IMPROVEMENT THU NIGHT. 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...
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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.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ350- 353-355. && $$ SYNOPSIS...JMC/MALOIT NEAR TERM...JMC SHORT TERM...JMC LONG TERM...MALOIT AVIATION...DW MARINE...JMC/MALOIT HYDROLOGY...JMC/MALOIT

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