Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 010815 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 415 AM EDT WED APR 1 2015 .SYNOPSIS...
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HIGH PRESSURE BUILDS TO THE WEST...THEN SOUTH OF THE TRI-STATE THROUGH TONIGHT. A WARM FRONT PASSES TO THE NORTH ON THURSDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST THURSDAY NIGHT...STALL NEAR THE AREA 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 FRONTAL SYSTEM WILL SLOWLY APPROACH MONDAY NIGHT INTO TUESDAY.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/... DEEP LAYERED RIDGE AXIS BEGINS TO BUILD IN FROM THE WEST TODAY...RESULTING SUBSIDENCE BY AFTERNOON WILL LIMIT MIXING TO 875-825 HPA PER BUFKIT SOUNDINGS. IT ALSO LIMIT LOW LEVEL CLOUDS DUE TO LOW LEVEL INSTABILITY TO FEW-SCT. SO ONLY REAL SOURCE OF CLOUDS IS MID-HIGH DECK TO THE WEST...WHICH SHOULD ALSO WORK ON THINNING UNDER THE RIDGE. AS A RESULT WENT WITH A SUNNY TO MOSTLY SUNNY FORECAST FOR TODAY. FOR HIGHS TODAY...USED A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER TEMPERATURES AND A MIX DOWN TO 875-825 HPA. HIGHS SHOULD BE AROUND 5 DEGREES BELOW NORMAL. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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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. 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.
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&& .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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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 NEAR THE AREA...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 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 RIGHT AT 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 GOOD CONTINUITY ON THE IDEA OF A FRONTAL SYSTEM APPROACHING FROM THE WEST LATE MON NIGHT INTO TUE...WITH PROLONGED CHANCES FOR RAIN. TEMPS SHOULD CONTINUE NEAR TO SLIGHTLY BELOW AVG.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
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HIGH PRES BUILDS INTO THE REGION TODAY. VFR THRU THE TAF PERIOD. NW WINDS THIS MORNING...BACKING TO THE WNW AFT 14Z. AN OCCASIONAL GUST POSSIBLE THRU 14Z...WITH PREVAILING GUSTS THEREAFTER. WINDS DECREASE LATE THIS AFTERNOON INTO THE EARLY EVE BECOMING LIGHT AND VRB OVERNIGHT. ...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. 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. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 06Z THURSDAY THROUGH SUNDAY... .WEDNESDAY NIGHT-THURSDAY...VFR. FLOW BECOMING SLY ON THU. .THURSDAY NIGHT-FRIDAY NIGHT...MVFR IN RAIN SHOWERS. .SATURDAY...SUB-VFR POSSIBLE IN SHOWERS EARLY...THEN VFR LATE. .SUNDAY...MAINLY VFR.
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&& .MARINE... SEAS ACROSS THE WATERS WERE AT 2 FT AS OF 7Z. LOOKING UPSTREAM 25 KT WIND GUSTS WERE CONTAINED WITH THE STRONGEST PRESSURE RISES OVER VA. THE TRAJECTORY OF THESE RISES IS NOT OVER THE AREA WATERS. ALSO...LATEST GUIDANCE KEEPS 950 HPA WINDS BELOW 25 KT. AS A RESULT...HAVE CANCELLED THE SMALL CRAFT ADVISORY FOR THE COASTAL OCEAN WATERS THAT WAS IN EFFECT INTO THIS AFTERNOON. EVEN WITH THE ABOVE...THERE SHOULD BE GUSTS UP TO AROUND 20KT THIS MORNING OVER THE COASTAL OCEAN WATERS. OTHERWISE...A DIMINISHING 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. && .HYDROLOGY... DRY THROUGH THURSDAY. 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...MALOIT SHORT TERM...MALOIT LONG TERM...GOODMAN AVIATION...JMC MARINE...GOODMAN/MALOIT HYDROLOGY...GOODMAN/MALOIT

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