Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 041228 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 728 AM EST WED MAR 4 2015 .SYNOPSIS... DEEPENING LOW PRESSURE TRACKS ACROSS EASTERN CANADA TODAY WITH A COLD FRONTAL BOUNDARY APPROACHING AS A WAVE OF LOW PRESSURE DEVELOPS ALONG IT SOUTHWEST OF THE REGION. THE COLD FRONT SLIDES TO THE SOUTHEAST TONIGHT...WITH WAVES OF LOW PRESSURE TRACKING ALONG IT INTO THURSDAY. CANADIAN HIGH PRESSURE THEN BUILDS IN THROUGH THURSDAY NIGHT...THEN SLIDES TO OUR SOUTH THROUGH FRIDAY NIGHT. A SERIES OF WEAK COLD FRONTS CROSS THE REGION THIS WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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FORECAST MAINLY ON TRACK. INCREASED POPS FOR RAIN ACROSS NORTHERN PARTS OF THE REGION. A WSW FLOW REMAINS ACROSS THE REGION THROUGH THE DAY TODAY. PRETTY MUCH A STEADY STATE ENVIRONMENT WITH TEMPS ONLY RISING A FEW DEGREES AND INTERMITTENT RAIN. THIS SHOULD BE MOSTLY LIGHT. THE UPPER LEVEL JET STREAK OF AROUND 200 KT WILL BE APPROACHING THROUGH THE DAY. TEMPS REMAIN GENERALLY IN THE MID TO UPPER 30S TO KEEP PRECIPITATION IN THE FORM OF PLAIN RAIN. THE INTENSITY WILL BE RATHER LIGHT DUE TO THE AREA NOT BEING IN A FAVORABLE REGION OF LIFT RELATIVE TO THE JET STREAK PLACEMENT BUT INCREASED DIVERGENCE ALOFT SHOULD ALLOW FOR RAIN FIELD TO EXPAND. TEMPERATURES USED WERE A COMBINATION OF GMOS...NAM12 AND GFS40...HOLDING WITHIN THE UPPER 30S FOR MOST LOCATIONS.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
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MODELS IN GOOD AGREEMENT WITH NORTHERN STREAM ENERGY DIGGING DOWN THE FRONT RANGE OF THE ROCKIES INTO NORTHERN PLAINS/UPPER GREAT LAKES TODAY...INTERACTING WITH A SW US LOW...AND THEN GRADUALLY LIFTING ACROSS THE US TO EAST COAST BY THURSDAY NIGHT. HAVE STAYED CLOSE TO ENSEMBLE MEANS...WITH A REINFORCING COLD FRONT MOVING SOUTH OF THE REGION THIS EVE WITH FALLING TEMPS TONIGHT. A SERIES OF WAVES WILL DEVELOP ALONG A STATIONARY FRONT TO THE SOUTH TRACKING NE THROUGH THE MID ATLANTIC...AHEAD OF APPROACHING UPPER TROUGH AXIS AND AS THE REGION FALLS UNDER FAVORABLE ENTRANCE REGION OF A 175-200KT UPPER JET. BIGGEST UNCERTAINTY EXISTS IN QPF...WITH MODELS WOBBLING BACK AND FORTH FROM RUN TO RUN ON NORTHERN EXTENT OF HEAVIER QPF AXIS. RELYING ON A ENSEMBLE APPROACH TO QPF...WITH 1/4 TO 3/4 INCH OF QPF ACROSS THE REGION AS THE SYNOPTIC SETUP TAPS INTO A MOIST SW FLOW ALL THE WAY FROM THE SUBTROPICAL PAC. ENSEMBLE INDICATING HIGHEST PROB OF .5 INCHES OR GREATER AFTER TRANSITION FOR SOUTHERN PORTIONS OF NYC/NJ METRO AND LI. MODELS IN GENERAL AGREEMENT WITH THERMAL PROFILES COOLING THROUGH THE OVERNIGHT...WITH A CHANGEOVER OF PRECIP FROM RAIN IN THE EARLY EVE TO WINTRY MIX THEN SNOW FROM NW TO SE. ALL AREAS APPEAR TO BE MAINLY SNOW BY 06Z. MODEST FRONTOGENETIC FORCING APPEARS TO BE ACROSS SOUTHERN ZONES...WITH POTENTIAL FOR SNOW TO BE HEAVY AT TIMES LATE TONIGHT THROUGH THU MORNING THERE...COUPLED WITH STRONG JET DYNAMICS. SNOW SHOULD GRADUALLY TAPER OFF IN INTENSITY AND COVERAGE FROM NW TO SE THURSDAY AFTERNOON AS SHORTWAVE TROUGH APPROACHES AND OFFSHORE STATIONARY FRONT SLIDES WELL OFFSHORE. HIGHEST CONFIDENCE IN 6+ INCH AMOUNTS IS FOR LI AND SOUTHERN PORTIONS OF NYC/NJ METRO. WILL UPGRADE TO WARNING IN THIS AREA AFTER COLLAB WITH PHI AND BOX. POTENTIAL FOR 3 TO 6 INCHES FOR COASTAL SOUTHERN CT...THE REST OF NE NJ...AND SOUTHERN PORTIONS OF LOWER HUDSON VALLEY. WILL LEAVE WATCH IN THESE AREAS WITH POTENTIAL FOR 6" BUT HIGHER LIKELIHOOD OF ADVISORY LEVEL. WITH A SHARP GRADIENT IN PRECIP ACROSS AREAS FAR N&W OF NYC...BETWEEN 1 TO 4 INCHES... NOT ENOUGH CONFIDENCE FOR AN ADVISORY AT THIS TIME. DRYING CONDITIONS THURSDAY NIGHT...WITH TEMPS DROPPING INTO THE SINGLE DIGITS...LOWER TEENS NYC METRO...ON GUSTY NW WINDS. WINDCHILLS LIKELY DROPPING TO AROUND ZERO TO 5 BELOW ZERO FOR MUCH OF THE REGION BY FRIDAY MORNING.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THEREAFTER...MEAN TROUGHING CONTINUES INTO EARLY NEXT WEEK. UNSEASONABLY COLD CONDS (ABOUT 20 DEGREES BELOW SEASONABLE) CONTINUE THU NIGHT INTO FRI NIGHT AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION. THEN A SERIES OF WEAK SHORTWAVE/COLD FRONTS MOVE THROUGH THE REGION THIS WEEKEND INTO EARLY NEXT WEEK...WITH TEMPS MODERATING BUT STILL REMAINING SEVERAL DEGREES BELOW SEASONABLE. SOME LIGHT RA/SN SHOWER ACTIVITY POSSIBLE WITH ANY OF THESE DISTURBANCES. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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LOW PRESSURE TRACKS ACROSS EASTERN CANADA TODAY...WITH ITS TRAILING COLD FRONT CROSSING THE AREA LATE THIS EVENING. PERIODS OF RAIN TODAY WITH GENERALLY MVFR CONDS EXPECTED...ALTHOUGH THE FORECAST IS VERY CHALLENGING OVER THE NEXT 24 HOURS. SEVERAL OF THE TERMINALS HAVE IMPROVED TO VFR THIS MORNING...BUT EXPECT THIS TO BE SHORT-LIVED. HOWEVER...CONDS COULD VARY BETWEEN MVFR AND VFR THROUGH THE DAY. GUIDANCE IS ALL OVER THE PLACE. COLD FRONT WILL TRACK THROUGH THE AREA LATE THIS EVENING AND STALL JUST S OF LONG ISLAND. SOUNDINGS INDICATE A CHANGE OVER FROM RAIN BACK TO SNOW AROUND 06Z. HOWEVER...MODEL DIFFERENCES REMAIN WITH WHERE THE NORTHERN EDGE OF THE PCPN FIELD WILL BE TONIGHT WHICH RESULTS IN HIGH UNCERTAINTY IN CONDS. SW FLOW EXPECTED TO PREVAIL UNTIL FROPA THIS EVE...BETWEEN 02Z AND 06Z...THEN BECOMING NW. GUSTS UP TO 20 KT POSSIBLE LATE. ..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: FLIGHT CATEGORY MAY VARY BETWEEN MVFR AND VFR. KLGA FCSTER COMMENTS: FLIGHT CATEGORY MAY VARY BETWEEN MVFR AND VFR. KEWR FCSTER COMMENTS: FLIGHT CATEGORY MAY VARY BETWEEN MVFR AND VFR. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS MODERATE...WHICH IMPLIES SLANT RANGE VISIBILITY 4-6SM OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: FLIGHT CATEGORY MAY VARY BETWEEN MVFR AND VFR. KHPN FCSTER COMMENTS: FLIGHT CATEGORY MAY VARY BETWEEN MVFR AND VFR. KISP FCSTER COMMENTS: FLIGHT CATEGORY MAY VARY BETWEEN MVFR AND VFR. .OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY... .THURSDAY...-SN WITH IFR TO MVFR COASTAL TERMINALS...MVFR TO VFR KSWF. N GUSTS TO 20 KT IN THE MORNING. .THURSDAY NIGHT-FRIDAY...IMPROVING TO VFR THURS NIGHT. NW GUSTS 15-20KT POSSIBLE THURSDAY NIGHT. .SAT/SUN...VFR.
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&& .MARINE...
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SCA CONDITIONS ARE EXPECTED TO CONTINUE ACROSS THE OCEAN WITH OTHER WATERS REMAINING BELOW SCA. THE SCA EVENT WILL BE MORE OF A MARGINAL ONE AND DUE MAINLY TO SEAS BUT ANY RAINFALL WILL BE OF HELP TO TRANSPORT MOMENTUM DOWNWARD AND GIVE SOME HIGHER GUSTS THAT WOULD REACH SCA THRESHOLDS. WATER TEMPS ARE A FEW DEGREES WARMER ON THE OCEAN RELATIVE TO OTHER WATERS SO IT WILL BE RELATIVELY EASIER FOR HIGHER GUSTS TO BE ACHIEVED ON THE OCEAN. SMALL CRAFT ADVISORY CONDITIONS ARE LIKELY ON THE COASTAL OCEAN WATERS TONIGHT INTO THURSDAY MORNING AS A SERIES OF LOW PRESSURE WAVES TRACKS TO THE SOUTH OF THE WATERS. SOME UNCERTAINTY IF SCA CONDS CONTINUE INTO THU AFTERNOON...WITH HIGHER CONFIDENCE OF RE- OCCURRENCE THU NIGHT. SO FOR NOW HAVE ONLY RUN SCA UNTIL THU MORNING. SUB SCA CONDS RETURN FRI AS HIGH PRESSURE BUILDS OVER THE WATERS. A SERIES OF WEAK COLD FRONTS WILL MOVE THROUGH THE WATERS THIS WEEKEND INTO EARLY NEXT WEEK...ONE SATURDAY NIGHT INTO SUNDAY MORNING AND ANOTHER MONDAY NIGHT. WINDS APPROACH SCA CRITERIA SATURDAY INTO SATURDAY NIGHT AND THEN AGAIN MONDAY NIGHT INTO TUESDAY ON THE OCEAN WATERS...BUT AS OF RIGHT NOW...THEY SHOULD REMAIN BELOW. WAVES REMAIN BELOW SCA CRITERIA THROUGH THE PERIOD.
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&& .HYDROLOGY...
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AROUND A QUARTER OF AN INCH OR LESS IS EXPECTED WITH THE RAINFALL TODAY. LOW POTENTIAL FOR FLOODING ALTHOUGH SOME PONDING OF WATER IS EXPECTED WITH STEADY MODERATE RAIN THAT FALLS DUE TO EXCESS RUNOFF FROM MELTING SNOWPACK. 1/4 TO 3/4 INCH LIQUID EQUIVALENT PRECIPITATION IS LIKELY WEDNESDAY NIGHT INTO THURSDAY. MOST OF THIS WILL BE FROZEN...SO HYDROLOGIC IMPACTS ARE NOT EXPECTED.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR CTZ008>012. NY...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST THURSDAY FOR NYZ074-075-078>081-176>179. WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR NYZ071>073. NJ...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 7 PM EST THURSDAY FOR NJZ107-108. WINTER STORM WATCH FROM THIS EVENING THROUGH THURSDAY EVENING FOR NJZ002-004-006-103>106. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...JM/NV NEAR TERM...JM SHORT TERM...NV LONG TERM...JP AVIATION...24 MARINE...JM/JP/NV HYDROLOGY...JM/NV

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