Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 162116 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 416 PM EST TUE DEC 16 2014 .SYNOPSIS...
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LOW PRESSURE APPROACHES TONIGHT AND MOVES TO THE EAST WEDNESDAY AND WEDNESDAY NIGHT. THE REGION REMAINS IN BETWEEN CANADIAN HIGH PRESSURE TO OUR WEST AND A MEANDERING LOW OVER THE CANADIAN MARITIMES THURSDAY AND THURSDAY NIGHT. THE HIGH THEN BUILDS OVER THE AREA THROUGH SATURDAY...THEN SLOWLY RETREATS TO THE NORTHEAST INTO EARLY NEXT WEEK. MEANWHILE...LOW PRESSURE DEVELOPS ALONG THE GULF COAST LATE THIS WEEK...TRACKS TO OFF THE CAROLINA COAST BY SUNDAY MORNING...AND TO SOUTH OF NOVA SCOTIA BY MONDAY MORNING. HIGH PRESSURE THEN BUILDS DOWN FROM SOUTHEASTERN CANADA INTO TUESDAY.
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&& .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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A PRIMARY LOW PRESSURE CENTER MOVES ACROSS THE EASTERN GREAT LAKES REGION. AN ASSOCIATED WARM FRONT APPROACHES US AS A SECONDARY LOW PRESSURE CENTER DEVELOPS ALONG THE FRONTAL BOUNDARY AND PASSES THROUGH THE CWA AFTER MIDNIGHT. RAIN OVERSPREADS THE CWA WEST TO EAST THIS EVENING. THIS WILL BE A RELATIVELY QUICK-MOVING SYSTEM...SO STEADIER RAINFALL ENDS AFTER MIDNIGHT FOR MOST SPOTS...WITH SCATTERED SHOWERS REMAINING AS TRAILING SHORTWAVE ENERGY PASSES THROUGH. AFTER AN INITIAL TEMPERATURE DROP-OFF EARLY ON...TEMPERATURES REMAINING FAIRLY STEADY THEREAFTER THROUGH THE NIGHT.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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A LINGERING SHOWER POSSIBLE OVER THE FAR EASTERN PORTION OF THE CWA EARLY ON WEDNESDAY MORNING...OTHERWISE THE MORNING WILL BE DRY. A SHORTWAVE APPROACHES FROM THE WEST DURING THE AFTERNOON WITH ENOUGH MOISTURE FOR A SLIGHT CHANCE OF A SHOWER NORTH OF THE CITY. STRONGER COLD AIR ADVECTION WILL BE DELAYED ENOUGH...COMBINED WITH A MODERATE WEST DOWNSLOPING WIND...TO ALLOW TEMPERATURES TO RISE TO AROUND 50 ON AVERAGE. SLIGHT CHANCE POPS DURING THE EVENING HOURS ACROSS THE REGION AS THE SHORTWAVE PASSES THROUGH. PRECIPITATION TYPE EXPECTED TO BE RAIN...EXCEPT MIXED RAIN AND SNOW WELL INLAND. AFTER MIDNIGHT...ANOTHER SHORTWAVE APPROACHES FROM THE WEST...BUT PROBABLY WITH LESS MOISTURE TO WORK WITH. HAVE GONE WITH A SPRINKLE OR FLURRY POSSIBLE OVER EASTERN ZONES FOR THIS TIME FRAME...RELATED TO THE POSITIVE VORTICITY ADVECTION AND AVAILABLE MOISTURE ASSOCIATED WITH THE FIRST SHORTWAVE.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/...
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SOUTHERN STREAM SHORTWAVE RIDGE TRIES TO UNDERCUT CUTOFF LOW NEAR NOVA SCOTIA ON THURSDAY. RESULT WILL BE NON-UNIDIRECTIONAL LOW LEVEL FLOW - SO THAT...COUPLED WITH POSSIBLE SUBSIDENCE FROM THE RIDGE...DEPENDING ON HOW FAR N IT GETS...SHOULD PRECLUDE ANY WIDESPREAD FLURRIES ON THURSDAY. HAVE REMOVED FROM FORECAST AS A RESULT...HOWEVER ISOLATED FLURRIES EARLY THURSDAY OVER FAR E ZONES AND DURING THE DAY OVER HIGHER ELEVATIONS IN FAR N/W PORTIONS OF THE LOWER HUDSON VALLEY CANNOT BE COMPLETELY RULED OUT. HOWEVER CONFIDENCE IN OCCURRENCE IS TOO LOW TO REFLECT IN THE OFFICIAL FORECAST. APPEARS SHOULD HAVE SOME LOW LEVEL MOISTURE TRAPPED UNDER A DEVELOPING INVERSION WITH A BASE AROUND 925 HPA SO WOULD EXPECT PARTLY SUNNY SKY CONDITIONS. FAIRLY TIGHT PRESSURE GRADIENT OVER THE REGION...SO SHOULD BE BREEZY TO WINDY AS WELL. FOR HIGHS THURSDAY A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 925 HPA PER BUFKIT SOUNDINGS WAS USED. THIS SHOULD YIELD NEAR NORMAL TEMPERATURES. A WEAK 500-700 HPA SHORTWAVE CROSSES THE AREA THURSDAY NIGHT IN THE WAKE OF THE AFOREMENTIONED SHORTWAVE RIDGE. FOR NOW APPEARS FORCING WILL BE TOO WEAK TO PRODUCE ANY PRECIPITATION...SO KEPT THE FORECAST DRY. FOR LOWS THURSDAY NIGHT A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE NEAR TO SLIGHTLY ABOVE NORMAL. A NORTHERN STREAM RIDGE BUILDS IN OVER SW QUEBEC FRIDAY...AND TRACKS EAST FRIDAY NIGHT...WITH ASSOCIATED SUBSIDENCE KEEPING THINGS DRY. FOR HIGHS FRIDAY USED A BLEND OF MEX/MEN/EKD/ECE/ECM GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 925 HPA PER BUFKIT SOUNDINGS. VALUES SHOULD BE A FEW DEGREES BELOW NORMAL. FOR LOWS FRIDAY NIGHT A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WAS USED...WITH READINGS FORECAST TO BE SLIGHTLY BELOW NORMAL. DEVELOPING DEEP LAYERED RIDGE AXIS SLIDES TO THE EAST SATURDAY...POSSIBLY ALLOWING FOR SOME LIGHT RAIN TO REACH FAR SW ZONES BY LATE AFTERNOON IN RESPONSE TO LOW LEVEL WARM ADVECTION. MODELS CONTINUE TO DISPLAY DIFFERENCES WITH RESPECT TO THE TIMING AND STRENGTH OF A COASTAL LOW FORECAST TO IMPACT THE AREA FROM LATE SATURDAY...POSSIBLY INTO MONDAY. 12Z CMC IS NOW MOST PROGRESSIVE WITH THE SYSTEM...WITH 12Z ECMWF NOT TO FAR BEHIND. GFS AND GEFS AS WELL AS ECMWF ENSEMBLE MEANS ARGUE FOR A SOMEWHAT SLOWER SOLUTION...SO LEANED TOWARDS GEFS MEAN TIMING WITH THE SYSTEM. MODELS GENERALLY AGREE ON A TRACK TO THE SE OF THE 40N/70W BENCHMARK - SO USED A BLEND FOR TRACK. THE CMC IS THE FASTEST TO DEEPEN THE LOW...WHILE MOST OTHER GUIDANCE SUGGESTS THE LOW DOES NOT DEEPEN UNTIL IT IS SE TO E OF THE AREA. LEANED TOWARDS SLOWER DEVELOPING ECMWF/GFS AND THEIR ENSEMBLE MEANS FOR SYSTEM STRENGTH. BASED ON THE ABOVE...APPEARS MOST PRECIPITATION FROM THIS SYSTEM WILL BE DUE TO SUPPORTING 850-500 HPA TROUGH TRACKING FROM THE WESTERN GREAT LAKES SATURDAY EVENING...TO SOME PLACE AROUND NOVA SCOTIA BY LATE MONDAY...AND LOW LEVEL WARM ADVECTION AHEAD OF THE TROUGH. AS A RESULT EXPECT PRECIPITATION TO BE RELATIVELY LIGHT. GIVEN UNCERTAINTY HAVE CAPPED POPS AT 50 PERCENT FOR NOW. STILL CANNOT RULE OUT THE AREA ULTIMATELY BEING IN BETWEEN THE UPPER SYSTEM LIFTING TO THE NE AND THE COASTAL LOW TO THE SE...WITH LITTLE OR NO PRECIPITATION...OR BETTER PHASING BETWEEN THE N AND S STREAMS...WITH COASTAL REDEVELOPMENT TO THE S...RESULTING IN MORE PRECIPITATION...AND MORE LIKELY MORE SNOW. TRACK OF THE LOW WOULD SUGGEST MAINLY SNOW...BUT TRACK OF THE 850-700 HPA TROUGH WOULD SUGGEST SOME WARMING OF THE LOW-MID LEVELS...MAKING P-TYPE POTENTIALLY MORE PROBLEMATIC. FOR NOW...WENT WITH A BLEND OF ECMWF AND GFS THERMAL PROFILES...WEIGHED TOWARDS COLDER ECMWF...AS GFS SEEMS WARMER THAN MOST IN THE LOW LEVELS...AND LIMITED P-TYPE POSSIBILITIES TO SNOW...SNOW/RAIN...OR RAIN FOR SIMPLICITY THIS FAR OUT. BASED ON THIS...EXPECT MAINLY SNOW ACROSS THE INTERIOR AND A SNOW-RAIN MIX ELSEWHERE SATURDAY NIGHT...TRANSITIONING TO MAINLY RAIN DURING THE DAY ON SUNDAY. PRECIPITATION SHOULD CHANGE BACK TO MAINLY SNOW ACROSS THE INTERIOR AND A RAIN-SNOW MIX ELSEWHERE SUNDAY NIGHT...BEFORE TAPERING OFF LATE SUNDAY NIGHT W/EARLY MONDAY MORNING E AS THE LOW EXITS TO THE NE. ONCE AGAIN...AT THIS TIME IT APPEARS PRECIPITATION SHOULD BE LIGHT...SO NO SIGNIFICANT IMPACT IS CURRENTLY EXPECTED...BUT AS NOTED ABOVE CANNOT BE COMPLETELY RULED OUT. FOR NOW KEPT THINGS DRY INTO TUESDAY AS DEEP LAYERED RIDGING BUILDS IN. HOWEVER THERE ARE SOME INDICATIONS THAT SOME OVER RUNNING PRECIPITATION COULD ENCROACH ON SW ZONES BY LATE TUESDAY...BUT CONFIDENCE IN THIS IS NOT HIGH ENOUGH TO PUT IN THE FORECAST QUITE YET. FOR TEMPERATURES SATURDAY-TUESDAY USED A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE...WITH ECMWF 2-METER TEMPERATURES BLENDED IN SATURDAY NIGHT-SUNDAY NIGHT. BELOW NORMAL TEMPERATURES ARE FORECAST SATURDAY...WITH NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES SATURDAY NIGHT-TUESDAY. THIS IS SUBJECT TO CHANGE BASED ON EVENTUAL TRACK AND STRENGTH OF COASTAL LOW THIS WEEKEND...WITH EXPECTATION THAT TEMPERATURES MOST LIKELY WOULD TREND LOWER AND NOT WARMER IF CHANGES ARE MADE.
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&& .AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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A FRONTAL SYSTEM WILL MOVE ACROSS THE AREA TONIGHT...PRECEDED BY GRADUALLY LOWERING CIGS AND AN E/SE FLOW AROUND 5 KT. MVFR CONDITIONS EARLY THIS EVENING LIKELY TO LOWER TO IFR...WITH SLOW IMPROVEMENT FOLLOWING THE FRONTAL PASSAGE AFTER 08Z. A GUSTY WEST FLOW DEVELOPS BY LATE WED MORNING...WITH G20-25KT BY AFT. 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: TIMING OF IFR CIGS MAY BE DELAYED BY 1-2 HOURS THIS EVENING. KLGA FCSTER COMMENTS: TIMING OF IFR CIGS MAY BE DELAYED BY 1-2 HOURS THIS EVENING. KEWR FCSTER COMMENTS: TIMING OF IFR CIGS MAY BE DELAYED BY 1-2 HOURS THIS EVENING. KTEB FCSTER COMMENTS: TIMING OF IFR CIGS MAY BE DELAYED BY 1-2 HOURS THIS EVENING. KHPN FCSTER COMMENTS: TIMING OF IFR CIGS MAY BE DELAYED BY 1-2 HOURS THIS EVENING. KISP FCSTER COMMENTS: TIMING OF IFR CIGS MAY BE DELAYED BY 1-2 HOURS THIS EVENING. .OUTLOOK FOR 18Z WED THROUGH SAT... .WED AFT/NIGHT...VFR. W 10-15KT. GUSTS 20-25KT. .THU...VFR. NW 10-15KT. GUSTS 20-25KT. .FRI-SAT...VFR. .SUN...SUB-VFR IN RAIN AND/OR SNOW.
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&& .MARINE...
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A RELATIVELY WEAK LOW PRESSURE CENTER PASSES THROUGH THE AREA WATERS TONIGHT. ONSHORE WINDS THIS EVENING SHIFT TO THE WEST BY LATE AND BECOME MORE GUSTY. SCA CONDITIONS ON THE OCEAN WATERS STARTING DURING THE MORNING...AND ON THE OTHER WATERS MID-AFTERNOON. SCA CONDITIONS THEN CONTINUE THROUGH THURSDAY WITH PERHAPS A GUST OR TWO UP TO GALE FORCE OVER THE OCEAN WATERS FOR COUPLE OF HOURS THURSDAY MORNING. GUSTY WINDS WILL GUST TO SCA LEVELS ON ALL WATERS THURSDAY AND ON LIKELY ON THE COASTAL OCEAN AND EASTERN WATERS THURSDAY NIGHT...AND POSSIBLY ON THE REMAINDER OF THE WATERS AS WELL. OCCASIONAL GUSTS TO GALE FORCE ARE PROBABLE ON THE COASTAL OCEAN WATERS THURSDAY AS WELL. CONDITIONS SHOULD SUBSIDE BELOW SCA LEVELS ON ALL WATERS BY LATE FRIDAY...WITH SUB-SMALL CRAFT CONDITIONS EXPECTED FROM LATE FRIDAY INTO SUNDAY FOR NOW. HOWEVER...WILL HAVE TO MONITOR A COASTAL LOW FORECAST FOR NOW TO TRACK WELL TO THE SE THIS WEEKEND. STILL QUITE A BIT UNCERTAINTY ON EXACT TRACK...STRENGTH...AND TIMING...SO ABOVE NORMAL POTENTIAL FOR THE FORECAST TO CHANGE.
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&& .HYDROLOGY...
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1/4 TO 1/2 INCH OF RAIN IS EXPECTED THROUGH EARLY WEDNESDAY MORNING. NO HYDROLOGIC ISSUES ARE ANTICIPATED. NO SIGNIFICANT PRECIPITATION - WIDESPREAD 1/2 INCH OR GREATER QPF - IS EXPECTED FROM AROUND MIDDAY WEDNESDAY INTO EARLY NEXT WEEK AT THIS TIME. IT SHOULD BE DRY FROM THURSDAY THROUGH AT LEAST SATURDAY MORNING IN THIS TIME FRAME.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 3 PM WEDNESDAY TO 6 PM EST THURSDAY FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY FROM 6 AM WEDNESDAY TO 6 PM EST THURSDAY FOR ANZ350-353-355.
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&& $$ SYNOPSIS...JC/MALOIT NEAR TERM...JC SHORT TERM...JC LONG TERM...MALOIT AVIATION...DW MARINE...JC/MALOIT HYDROLOGY...JC/MALOIT

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