Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 032133 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 433 PM EST TUE MAR 3 2015 .SYNOPSIS...
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DEEPENING LOW PRESSURE TRACKS ACROSS EASTERN CANADA TONIGHT INTO WEDNESDAY...PRECEDED BY A WARM FRONTAL PASSAGE LATE TONIGHT. THE TRAILING COLD FRONT CROSSES THE AREA WEDNESDAY NIGHT...WITH WEAK WAVES OF LOW PRESSURE RIDING ALONG IT INTO THURSDAY. HIGH PRESSURE THEN BUILDS IN FROM THE WEST INTO FRIDAY. A SERIES OF WEAK COLD FRONTS CROSS THE REGION THIS WEEKEND INTO EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH WEDNESDAY/...
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STRONG WARM ADVECTION PRECEDING A WARM FRONT THIS EVENING WILL ALLOW FOR A SHORT PERIOD OF MODERATE TO HEAVY SNOW...THAT WILL QUICKLY TRANSITION OVER TO A WINTRY MIX AND THEN ALL RAIN. MOST LOCATIONS WILL SEE ALL RAIN DEVELOP BETWEEN 9 PM AND MIDNIGHT FROM SOUTH TO NORTH EXCEPT FOR SOME INTERIOR VALLEY LOCATIONS WHERE THE COLD AIR GETS TRAPPED. IN ADDITION...WITH A SNOWPACK IN PLACE AND A PROLONGED PERIOD OF BELOW NORMAL TEMPS...FREEZING RAIN WILL BE POSSIBLE AT THE GROUND EVEN IF OBS SHOWS TEMPS JUST ABOVE FREEZING. MOST LOCATIONS WILL SEE 1 TO 3 INCHES OF SNOW WITH A LIGHT ICE ACCRETION BEFORE CHANGING OVER TO ALL RAIN. TEMPS WILL GRADUALLY RISE THROUGH THE OVERNIGHT WITH ACTUAL HIGH TEMPS EARLY THIS EVENING RIGHT AROUND OR JUST BELOW FREEZING. BY DAYBREAK...MOST LOCATIONS WILL BE 35 TO 40. USED A BLEND OF THE MET MOS WITH 2M HIGH RES WRF NMM TEMPS. THERE WILL BE A CHANCE OF LIGHT RAIN ON WED...WITH THE BEST CHANCE RIGHT ALONG THE COAST. TEMPS WILL REMAIN NEARLY STEADY IN THE MID TO UPPER 30S. RAINFALL AMOUNTS WILL GENERALLY BE AROUND ONE-HALF INCH DURING THIS TIME PERIOD.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
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THREAT CONTINUES FOR AROUND 6 INCHES OF SNOW ACROSS NYC/LONG ISLAND/NE NJ/N COAST OF LONG ISLAND SOUND...AND ALL OF FAR SE CT. MODELS CONTINUE TO ADVERTISE ANAFRONTAL NATURE OF A COLD FRONT PASSING WEDNESDAY NIGHT...IN RESPONSE TO REGION BEING IN THE RIGHT REAR QUADRANT OF A 180-200KT 250 HPA JET AND PASSING OF NORTHERN STREAM SHORTWAVES AT 700 HPA...THEN APPROACH OF 500 HPA SHORTWAVE LATER THURSDAY. MODELS ALSO AGREE IN SHIFTING PRIMARY AXIS OF QPF JUST TO THE S OF LONG ISLAND...THIS SERVERS TO LIMIT THE THREAT TO N INTERIOR ZONES...WITH THE EXCEPTION OF N NEW LONDON COUNTY...GIVEN FORECAST WSW TO ENE ORIENTATION OF THE QPF AXIS. MODELS ALSO HAVE COME INTO BETTER AGREEMENT WITH THE TIMING OF THE CHANGE OVER FROM RAIN TO SNOW WEDNESDAY EVENING...WITH A PERIOD OF SLEET MIXED IN DURING THE TRANSITION. THE CMC AND NAM REMAIN THE SLOWEST TO COOL THE LOW LEVELS...BUT NOW ARE ONLY A FEW HOURS SLOWER THAN A GFS/ECMWF/SREF BLEND. GIVEN TREND IN LOW LEVEL THERMAL FIELDS...USED A GFS/ECMWF/SREF BLEND TO DETERMINE CHANGE OVER TIMING. BASICALLY EXPECT THE TRANSITION TO OCCUR FAIRLY QUICKLY IN THE EVENING OVER N INTERIOR ZONES...AND CLOSER TO AROUND MIDNIGHT/SHORTLY THEREAFTER ACROSS SOUTHERN ZONES. THERE IS STILL QUITE A BIT OF UNCERTAINTY ON 1) HOW FAR N/W OF NYC SIGNIFICANT PRECIPITATION WILL FALL...AND 2) WHETHER OR NOT THE QPF AXIS WILL CONTINUE TO SHIFT FARTHER TO THE S. THERE IS STILL SOME UNCERTAINTY ON 1) THE EXACT TIMING OF CHANGE OVER 2) HOW MUCH SLEET IN THE TRANSITION WILL LIMIT SNOW AMOUNTS 3) THE EXACT END TIME OF PRECIPITATION - MODELS HAVE EXTENDED THE DURATION FOR THE MOST PART INTO THURSDAY AFTERNOON WHILE THE CMC CONTINUES INTO THURSDAY EVENING. HAVE DISCOUNTED CMC AS OUTLIER SOLUTION ON THIS FOR NOW...BUT DO NOTE IT HAS BEEN ADVERTISING A LONGER DURATION SINCE YESTERDAY. FOR NOW HAVE ISSUED A WINTER STORM WATCH FROM 7PM WEDNESDAY THROUGH 7PM THURSDAY FOR NYC/LONG ISLAND/NE NJ/S WESTCHESTER COUNTY/ALL OF COASTAL CT PLUS N NEW LONDON COUNTY AS WELL...FOR THE POTETNIAL FOR 4 TO 8 INCHES OF SNOW. OUTSIDE OF THE WATCH AREA THERE IS THE POTENTIAL FOR 3 TO 6 INCHES OF SNOW. 500 HPA TROUGH AXIS EXITS TO THE EAST THURSDAY NIGHT...FOLLOWED BY NORTHERN STREAM SHORTWAVE RIDGING BUILDING INTO FRIDAY MORNING...THEN PUSHING OFFSHORE FRIDAY AFTERNOON. WITH NO SIGNIFICANT FORCING EXPECTED HAVE GONE DRY THURSDAY NIGHT AND FRIDAY...EXCEPT FOR A LINGERING CHANCE OF SNOW MAINLY OVER THE SE 1/2 OF THE CWA EARLY THURSDAY EVENING. TEMPERATURES IN THE SHORT TERM WERE BASED ON A BLEND OF AVAILABLE GUIDANCE WITH NAM 2-METER TEMPERATURES. GFS 2-METER TEMPERATURES WERE BLENDED IN AS WELL THURSDAY NIGHT...AS THEY HAVE FAIRED WELL THIS YEAR SO FAR DURING COLD ADVECTION PATTERNS. TEMPERATURES ARE FORECAST TO REMAIN BELOW NORMAL WEDNESDAY NIGHT-FRIDAY. LOWS SHOULD RUN AROUND 5 DEGREES BELOW NORMAL WEDNESDAY NIGHT AND HIGHS 15-20 DEGREES BELOW NORMAL THURSDAY. LOWS THURSDAY NIGHT SHOULD BE MAINLY IN THE POSITIVE SINGLE DIGITS...AROUND 20-25 DEGREES BELOW NORMAL. WIND CHILLS THURSDAY NIGHT SHOULD GENERALLY BE IN THE NEGATIVE SINGLE DIGITS. HIGHS FRIDAY SHOULD BE AROUND 15 DEGREES BELOW NORMAL.
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&& .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
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RATHER TRANQUIL IN THE LONG TERM DESPITE THE FACT THAT AN UPPER LEVEL LOW TO THE NORTHWEST OF HUDSON BAY WILL SEND A COUPLE OF FRONTS THROUGH THE REGION...ONE SATURDAY NIGHT INTO SUNDAY MORNING...AND ANOTHER MONDAY NIGHT. THESE FRONTS WILL BE WEAK...WITH LITTLE MOISTURE TO WORK WITH. IN FACT...AS OF RIGHT NOW...THE COLD FRONT FOR SATURDAY NIGHT LOOKS TO COME THROUGH THE AREA DRY...WHILE THE COLD FRONT ON MONDAY NIGHT WILL ALLOW FOR JUST A SLIGHT CHANCE FOR SNOW SHOWERS. HIGH PRESSURE BUILDS IN FOR TUESDAY WITH DRY CONDITIONS. TEMPERATURES ON SATURDAY AND SUNDAY WILL BE IN THE 30S REGION-WIDE. TEMPERATURES WARM INTO THE LOWER 40S FOR THE BEGINNING OF THE WORK WEEK. WITH NORMAL HIGHS THIS TIME OF YEAR IN THE MIDDLE TO UPPER 40S...THESE TEMPERATURES WILL STILL BE BELOW NORMAL.
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&& .AVIATION /21Z TUESDAY THROUGH SUNDAY/... A WARM FRONT APPROACHES TONIGHT AND MOVES THROUGH LATE. LIGHT TO MODERATE SNOW WITH MVFR TO IFR CONDITIONS SPREADS EAST ACROSS THE TERMINALS INTO EARLY EVENING. PRIMARILY IFR OR LOWER EXPECTED TONIGHT AFTER 00-02Z. SNOW TRANSITIONS TO A WINTRY MIX FROM SW TO NE AS THE EVENING PROGRESSES...THEN RAIN OVERNIGHT. SSE WINDS BCMG SW-W OVERNIGHT. LLWS DURING THE LATE NIGHT HOURS. ..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: A BRIEF PERIOD OF -FZRA COULD OCCUR SOMEWHERE WITHIN 00Z-02Z. ANY ICE ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF 1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN. KLGA FCSTER COMMENTS: A BRIEF PERIOD OF -FZRA COULD OCCUR SOMEWHERE WITHIN 00Z-02Z. ANY ICE ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF 1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN. KEWR FCSTER COMMENTS: A BRIEF PERIOD OF -FZRA COULD OCCUR SOMEWHERE WITHIN 2230Z-02Z. ANY ICE ACCRETION WILL BE VERY LIGHT. RUNWAY ACCUMULATION OF SNOW/SLEET OF 1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN. KTEB FCSTER COMMENTS: ICE ACCRETION OF A TRACE TO A FEW HUNDREDTHS OF AN INCH. RUNWAY ACCUMULATION OF SNOW/SLEET OF 1 OR 2 INCHES BEFORE CHANGEOVER TO FREEZING RAIN. KHPN FCSTER COMMENTS: ICE ACCRETION OF A TRACE TO A FEW HUNDREDTHS OF AN INCH. RUNWAY ACCUMULATION OF SNOW/SLEET OF AROUND 2 INCHES BEFORE CHANGEOVER TO FREEZING RAIN. KISP FCSTER COMMENTS: RUNWAY ACCUMULATION OF SNOW/SLEET OF 1 OR 2 INCHES BEFORE CHANGEOVER TO RAIN. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .WEDNESDAY...MVFR/IFR IN -RA. .WEDNESDAY NIGHT-THURSDAY...IFR WITH A TRANSITION BACK TO SNOW LATE EVENING/NEAR MIDNIGHT. CHC N GUSTS TO 20 KT ON THURSDAY. .THURSDAY NIGHT-FRIDAY...IMPROVING TO VFR THURS NIGHT. NW GUSTS 15-20KT POSSIBLE THURSDAY NIGHT. .SAT/SUN...VFR. && .MARINE...
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MARGINAL SCA CONDITIONS FORECAST ON THE OCEAN WATERS TONIGHT INTO WEDNESDAY IN THE W/SW FLOW AHEAD OF AN APPROACHING FRONTAL SYSTEM. THE STRONGEST WINDS AND HIGHEST SEAS WILL BE LATE TONIGHT INTO WED MORNING. WAVEWATCH COULD BE UNDERDONE HERE BY A FOOT. SMALL CRAFT CONDITIONS ARE POSSIBLE ON THE COASTAL OCEAN WATERS EAST OF MORICHES INLET ON WEDNESDAY NIGHT...THEN ON ALL COASTAL OCEAN WATERS THURSDAY AND THURSDAY NIGHT...AND POSSIBLY INTO FRIDAY AS WELL. A SERIES OF WEAK COLD FRONTS WILL MOVE THROUGH THE WATERS...ONE SATURDAY NIGHT INTO SUNDAY MORNING AND ANOTHER MONDAY NIGHT. THESE FRONTS WILL BE WEAK...WITH JUST A SLIGHT CHANCE OF SNOW SHOWERS FOR MONDAY AND 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 TOTAL 1/2 TO 3/4 INCH OF LIQUID EXPECTED THROUGH WEDNESDAY. A LITTLE LESS THAN HALF OF IT BEING IN FORM OF WINTRY PRECIP. SOME PONDING OF WATER IS EXPECTED WITH STEADY MODERATE RAIN THAT FALLS DUE TO EXCESS RUNOFF FROM MELTING SNOWPACK. FROM AROUND .4 TO .9 INCHES OF QPF IS CURRENTLY FORECAST FROM WEDNESDAY NIGHT INTO THURSDAY EVENING...WITH MOST OF THIS FALLING IN THE FORM OF FROZEN PRECIPITATION. THERE IS STILL SOME UNCERTAINTY IN AMOUNTS...WITH LOWER AMOUNTS MORE LIKELY THAN HIGHER AMOUNTS. THERE IS ALSO SOME UNCERTAINTY IN HOW FAST THE RAIN CHANGES TO FROZEN PRECIPITATION WEDNESDAY NIGHT OVER NYC METRO/LONG ISLAND. THE LONGER THIS TAKES...IT INCREASES THE RISK OF POSSIBLE PONDING OF WATER.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR CTZ009>012. WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING FOR CTZ008>012. WINTER WEATHER ADVISORY UNTIL 5 AM EST WEDNESDAY FOR CTZ005>008. NY...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NYZ071>075-078>081-176>179. WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING FOR NYZ071>075-078>081-176>179. WINTER WEATHER ADVISORY UNTIL 5 AM EST WEDNESDAY FOR NYZ067>070. NJ...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NJZ004- 006-103>108. WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING FOR NJZ002-004-006-103>108. WINTER WEATHER ADVISORY UNTIL 5 AM EST WEDNESDAY FOR NJZ002. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST WEDNESDAY FOR ANZ353-355. SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 6 PM EST WEDNESDAY FOR ANZ350. && $$ SYNOPSIS...MALOIT/JP/DW NEAR TERM...DW SHORT TERM...MALOIT LONG TERM...JP AVIATION...JC MARINE...MALOIT/JP/DW HYDROLOGY...MALOIT/DW

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