Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 011439 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1039 AM EDT WED APR 1 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD TO THE WEST AND THEN SOUTH OF THE AREA THROUGH TONIGHT. A WARM FRONT WILL PASS TO THE NORTH ON THURSDAY. A COLD FRONT WILL FOLLOW FROM THE NORTHWEST THURSDAY NIGHT...STALL NEARBY ON FRIDAY...THEN PASS THROUGH LATE FRIDAY NIGHT INTO SATURDAY MORNING. HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND. WEAK LOW PRESSURE WILL PASS TO THE NORTH LATE SUNDAY NIGHT INTO MONDAY. A SLOW MOVING FRONTAL SYSTEM THEN BEGIN TO APPROACH MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PATCHY MID-DECK CLOUDS WILL MOVE ACROSS THE REGION THIS MORNING. OTHERWISE...WITH HIGH PRES BUILDING INTO THE NORTHEAST...CAN EXPECT SUBSIDENCE TO KEEP MANY CLOUDS FROM DEVELOPING LATER TODAY...RESULTING IN GENERALLY MOSTLY SUNNY SKIES. HIGH TEMPS TODAY SHOULD TOP OFF IN THE UPPER 40S TO AROUND 50...WHICH ARE AROUND 5 DEGREES BELOW AVG. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/... THE DEEP LAYERED RIDGE CONTINUES TO BUILD IN TONIGHT...THEN ITS AXIS CROSSES THE AREA THURSDAY. ASSOCIATED SUBSIDENCE MORE THAN LIKELY WILL KEEP THINGS DRY. HOWEVER...PASSING SURFACE TO 850 HPA WARM FRONT THURSDAY MORNING COULD BRING A FEW -SHRA/SPRINKLES TO MAINLY NORTHERN ZONES. FOR NOW...APPEARS SUBSIDENCE UNDER THE BUILDING RIDGE WILL WIN OUT...BUT CANNOT 100 PERCENT RULE OUT ANY PRECIPITATION ACROSS NORTHERN ZONES THURSDAY MORNING. THE PASSAGE OF THE SURFACE AND 850 WARM FRONT THOUGH WILL BRING SOME CLOUDS IN LATE TONIGHT AND THURSDAY MORNING...OTHERWISE THERE SHOULD BE MINIMAL CLOUD COVER TONIGHT AND THURSDAY...UNTIL HIGH CLOUDS BUILD IN OVER MAINLY W ZONES LATE THURSDAY AFTERNOON AHEAD OF THE NEXT SYSTEM. SHOULD SEE AN INCREASE IN WINDS THURSDAY AFTERNOON. AREAS MAINLY W OF THE HUDSON AND ALL FAR N INTERIOR ZONES COULD SEE GUSTS UP TO 20-25 MPH WITH ISOLATED 30-35 MPH POSSIBLE. FARTHER S/E...MARINE LAYER COULD PREVENT 25-50KT LOW LEVEL JET (STRENGTH INCREASES FROM W TO E) FROM REACHING THE GROUND. FOR LOWS TONIGHT...USED A BLEND OF MAV/MET/ECS GUIDANCE WITH THE PREVIOUS FORECAST. THE AFOREMENTIONED WARM FRONT GENERATED CLOUDS LIKELY WILL BE THE LIMITING FACTOR ON THE LOWS...SO DID NOT SIGNIFICANTLY UNDERCUT GUIDANCE IN NORMALLY COLDER LOCATIONS. LOWS SHOULD BE AROUND NORMAL IN NYC TO AROUND 5-10 DEGREES BELOW NORMAL ELSEWHERE. A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 1000-875 HPA PER BUFKIT SOUNDINGS WAS USED FOR HIGHS ON THURSDAY. SW LOW LEVEL FLOW WILL RESULT IN A WIDE RANGE OF TEMPERATURES WITH ONLY THE MID-UPPER 40S OVER THE TWIN FORKS AND FAR SE CT TO THE LOWER TO MAYBE MID 60S OVER NE NJ/WESTERN PORTIONS OF THE LOWER HUDSON VALLEY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... CLOUDS WILL INCREASE THU NIGHT AHEAD OF AN APPROACHING COLD FRONT. CHANCE SHOWERS MAINLY AFTER MIDNIGHT AND MAINLY NW OF THE CITY...WITH STILL THE POTENTIAL FOR SOME ELEVATED THUNDER. SHOWERS THEN BECOME LIKELY FRI INTO FRI NIGHT AS THE FRONT STALLS NEARBY...PASSING THROUGH LATE FRI NIGHT INTO EARLY SAT MORNING ONLY AFTER AN AMPLIFYING UPPER TROUGH AND ASSOCIATED SURFACE LOW PRESSURE PASS THROUGH. MAINTAINED CHANCE THUNDER FROM PREVIOUS FORECASTS SINCE THERE SHOULD BE AT LEAST SOME ELEVATED INSTABILITY...POSSIBLY SFC-BASED FOR A TIME FRI AFTERNOON FROM NYC NORTH/WEST AS HIGHS THERE REACH THE LOWER 60S. FARTHER EAST... WITH MORE OF AN ONSHORE FLOW EXPECT HIGHS IN THE LOWER 50S ALONG IMMEDIATE SOUTH FACING SHORES...AND MID/UPPER 50S ACROSS INTERIOR SOUTHERN CT AND THE NORTH SHORE OF LONG ISLAND. THE ONSHORE FLOW SHOULD ALSO BRING INCREASING POTENTIAL FOR FOG AS HIGHER DEWPOINT AIR TRAVERSES COLD ATLANTIC WATERS. JUST A LINGERING CHANCE OF A SHOWER SAT MORNING AS THE COLD FRONT EXITS...THEN A GUSTY DRYING NW FLOW SHOULD HELP CLOUDS DIMINISH CLOUDS AND KEEP US DRY DURING THE AFTERNOON. HIGHS WILL BE IN THE LOWER/MID 50S...NEAR OR JUST BELOW AVG. MEDIUM RANGE GUIDANCE STILL SUGGESTS A COLD FRONT DROPPING DOWN CLOSE TO THE AREA ON SUNDAY...AND THEREAFTER HAVE SIDED WITH 31/21Z AND 00Z ECMWF IDEA OF A CLIPPER-TYPE LOW RIDING THE FRONT IN QUASI- ZONAL FLOW ALOFT...WITH CHANCE POP FOR SNOW/RAIN SHOWERS MAINLY FOR THE INTERIOR LATE SUNDAY NIGHT INTO MON. GUIDANCE ALSO MAINTAINS FAIRLY GOOD CONTINUITY ON THE IDEA OF A SLOW MOVING FRONTAL SYSTEM APPROACHING FROM THE WEST LATE MON NIGHT INTO TUE...WITH PROLONGED CHANCES FOR RAIN. TEMPS SHOULD CONTINUE NEAR TO SLIGHTLY BELOW AVG. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... HIGH PRES BUILDS INTO THE REGION TODAY. VFR THRU THE TAF PERIOD. N/NW WINDS ARE EXPECTED TO BACK TO THE WNW THIS AFTERNOON. OCCASIONAL TO FREQUENT GUSTS ARE EXPECTED THIS AFTERNOON...GENERALLY UNDER 20 KTS. WINDS DECREASE LATE THIS AFTERNOON INTO THE EARLY EVE BECOMING LIGHT AND VRB OVERNIGHT. FLOW BECOMING SLY AFT 12Z THU WITH INCREASING SPEEDS THRU THE DAY. 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 ANY WIND SHIFT MAY BE OFF AN HOUR OR TWO AS WINDS SHOULD BACK TO THE LEFT OF 310 MAGNETIC. KLGA FCSTER COMMENTS: TIMING OF ANY WIND SHIFT MAY BE OFF AN HOUR OR TWO AS WINDS SHOULD BACK CLOSE TO 310 MAGNETIC. KEWR FCSTER COMMENTS: TIMING OF ANY WIND SHIFT MAY BE OFF AN HOUR OR TWO AS WINDS SHOULD BACK CLOSE TO 310 MAGNETIC. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. OCCASIONAL GUSTS EXPECTED THIS AFTERNOON. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. OCCASIONAL GUSTS EXPECTED THIS AFTERNOON. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. OCCASIONAL GUSTS EXPECTED THIS AFTERNOON AS WINDS BACK TO THE W/NW. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .THURSDAY...VFR. SLY FLOW INCREASING TO 20-30KT. .THURSDAY NIGHT-FRIDAY NIGHT...MVFR OR LOWER IN RAIN SHOWERS. WINDS BECOMING NW FRI. .SATURDAY...SUB-VFR POSSIBLE IN SHOWERS EARLY...THEN VFR LATE. NW FLOW. .SUNDAY...MAINLY VFR WITH NW FLOW. && .MARINE... SEAS HAD BUILT TO 3-4 FT WITH WIND GUSTS UP 20 TO KT AS OF 10Z. CORE OF BIGGEST 3-HRLY PRESSURE RISES AND ASSOCIATED 25+ KT GUSTS REMAINS TO THE SOUTH...AND TIGHTEST PRESSURE GRADIENT IS NOW TO THE EAST...SO STILL DO NOT EXPECT SCA CONDS THIS MORNING. THE WEAKENING PRESSURE GRADIENT THROUGH THURSDAY MORNING WILL KEEP WINDS AND SEAS BELOW SMALL CRAFT THRESHOLDS...WITH WINDS 10 KT OR LESS ON ALL WATERS BY TONIGHT. WINDS SHOULD INCREASE THURSDAY NIGHT...WITH TIGHTENING PRESSURE GRADIENT AHEAD OF THE NEXT SYSTEM. FOR NOW DO BRING GUSTS UP TO 25-30KT ON ALL WATERS THURSDAY AFTERNOON. HOWEVER...CONFIDENCE IN THIS IS NOT HIGH ENOUGH TO WARRANT ISSUING AN SCA AT THIS TIME. THERE IS SOME POTENTIAL THAT A SUFFICIENT LOW LEVEL MARINE INVERSION COULD FORM TO PRECLUDE SCA WIND GUSTS...WITH THE BEST CHANCE FOR ANY 25-30 KT GUSTS ON THURSDAY AFTERNOON OVER NY HARBOR/W LONG ISLAND SOUND/COASTAL OCEAN WATERS W OF FIRE ISLAND INLET. A PROLONGED PD OF SCA CONDITIONS PROBABLY WILL BE SETTING UP FOR THE OCEAN WATERS BEGINNING THU AFTERNOON...FIRST VIA INCREASING SOUTHERLY FLOW THU AFTERNOON INTO FRI AHEAD OF A SLOW MOVING COLD FRONT. THE FLOW MAY WEAKEN AHEAD OF THE FRONT FRI NIGHT...BUT LEFTOVER SWELLS WILL STILL BE HAZARDOUS DURING THAT TIME. NW TO W WINDS AFTER COLD FRONTAL PASSAGE SHOULD REACH SCA CRITERIA ON ALL WATERS ON SAT...THEN CONTINUE ON THE OCEAN SAT NIGHT INTO SUNDAY. && .FIRE WEATHER... RELATIVE HUMIDITIES THURSDAY AFTERNOON FALL TO 30-35 PERCENT OVER AREAS MAINLY W OF THE HUDSON...AND WINDS THURSDAY AFTERNOON THERE LIKELY WILL GUST TO 20-25 MPH WITH PEAK GUSTS OF 30-35 MPH POSSIBLE. AT THE MINIMUM THESE CONDITIONS COULD PROMOTE RAPID GROWTH/SPREAD OF ANY FIRES WHICH OCCUR THURSDAY AFTERNOON. && .HYDROLOGY... THERE IS POTENTIAL FOR 3/4 TO 1 INCH OF RAIN FROM LATE THU NIGHT INTO EARLY SAT MORNING. RIVERS AND STREAMS ARE EXPECTED TO REMAIN BELOW BANK FULL...BUT INCREASED RIVER/STREAM FLOW ACROSS THE LOWER HUDSON VALLEY AND SOUTHERN CONNECTICUT WILL CONTINUE ICE BREAKUP AND MOVEMENT INTO THIS WEEKEND. ISOLATED ICE JAMS ARE POSSIBLE...WHICH IF THEY OCCUR...COULD RESULT IN LOCALIZED FLOODING. SINCE ICE JAM FLOODING IS UNPREDICTABLE AND SUDDEN...INTERESTS ALONG ICE COVERED RIVERS SHOULD MONITOR NWS FORECASTS FOR THE LATEST INFORMATION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEB SITE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/MALOIT NEAR TERM...MPS SHORT TERM...MALOIT LONG TERM...GOODMAN AVIATION...JMC/PW MARINE...GOODMAN/MALOIT FIRE WEATHER... HYDROLOGY...GOODMAN/MALOIT

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