Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 242051 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 351 PM EST WED DEC 24 2014 .SYNOPSIS...
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A COLD FRONT APPROACHES FROM THE WEST THIS EVENING...AND CROSSES THE TRI-STATE OVERNIGHT...WITH ITS ASSOCIATED LOW TRACKING INTO QUEBEC THURSDAY. HIGH PRESSURE BUILDS TO THE SOUTH OF THE REGION THROUGH SATURDAY. A COLD FRONT THEN CROSSES THE REGION ON SUNDAY AND STALLS WELL TO OUR SOUTH ON MONDAY. A WEAK WAVE OF LOW PRESSURE MOVES ALONG THE FRONT ON TUESDAY AND MAY BRUSH NEW YORK CITY AND LONG ISLAND. AT THIS TIME NEW YEARS EVE AND DAY LOOK DRY WITH SEASONABLE TEMPERATURES.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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NUMEROUS ROUNDS OF MODERATE TO HEAVY RAIN WILL CONTINUE TO MOVE ACROSS THE REGION...AS A STRONG LOW LEVEL JET FILTERS IN UNSEASONABLY HIGH ATMOSPHERIC MOISTURE. THERE IS SOME INDICATION OF DRYING WORKING IN LATE THIS AFTERNOON BEFORE THE COLD FRONT PUSHES THROUGH THIS EVENING AND TONIGHT...BUT SHOWERS MAY STILL EXIST. A LINE OF SHOWERS MAY DEVELOP ALONG THE FRONT TONIGHT...WITH SOME POSSIBLE RUMBLES OF THUNDER. IF THIS OCCURS...SOME STRONGER GUSTS COULD MIX DOWN FROM ALOFT. TEMPERATURES TONIGHT WILL BE ABOVE NORMAL FOR THIS TIME OF YEAR...WITH TEMPERATURES RANGING BETWEEN MID 40S TO AROUND 50 DEGREES. SHOWERS SHOULD TAPER OFF RATHER QUICKLY EARLY THURSDAY MORNING AS THE COLD FRONT EXITS TO THE EAST. REFER TO THE HYDROLOGY SECTION OF THE AFD FOR TOTAL QPF AND ANY IMPACTS FROM THIS SYSTEM.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
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SHOWERS SHOULD TAPER OFF CHRISTMAS MORNING FROM WEST TO EAST...AS THE COLD FRONT MOVES OFFSHORE. BEHIND THE FRONTAL PASSAGE EXPECT DRY CONDITIONS WITH BELOW ADVISORY LEVEL WIND GUST OF 30 TO 40 MPH. WINDS WILL DIMINISH CHRISTMAS NIGHT AS THE FRONT PUSHES FURTHER EAST. THE MAX TEMPERATURES FOR CHRISTMAS DAY SHOULD BE IN THE LOW TO MID 50S...WITH TEMPERATURES DROPPING OFF INTO THE 40S BY LATE AFTERNOON AND EVENING. LOW TEMPERATURES CHRISTMAS NIGHT SHOULD BE IN THE UPPER 20 TO AROUND 30 INLAND...AND MID TO UPPER 30S ALONG THE COAST.
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&& .LONG TERM /FRIDAY THROUGH WEDNESDAY/...
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NWP GUIDANCE HAS MADE A SIGNIFICANT SHIFT TODAY WITH THE SOUTHERN BRANCH OF THE JET RESULTING A MORE PROGRESSIVE PATTERN. BASED ON AGREEMENT OF GEFS WITH THE DETERMINISTIC GFS AND ECMWF TREND...HAVE REPOPULATED FCST. 12Z GEM REMAINS MORE ACTIVE...BUT WAS NOT INCORPORATED INTO THE FCST BASED ON GEFS/EC SIMILARITY. THUS...FCSTING THE COLD FRONTAL PASSAGE ON SUNDAY...THEN SEASONABLE AND DRY. DUE TO THE SHIFT IN THE NWP...CONFIDENCE IS LOWER THAN NORMAL AND WE COULD HAVE A WINDSHIELD WIPER EFFECTS IN THE DETERMINISTIC GUIDANCE. ONLY POPS OUT SIDE OF THOSE WITH THE COLD FRONT ON SUNDAY ARE LATE TUESDAY WITH A WEAK WAVE SEEN IN THE ECMWF. GEFS HAS SOME MEMBERS THAT SUPPORT THIS FEATURE (NOT SEEN IN THE DETERMINISTIC GFS). AS FOR TEMPS...MOS HAS TRENDED HIGHER FRIDAY AND SATURDAY AND SEEMS LOGICAL WITH TEMPS A GOOD 10 DEGREES ABOVE NORMAL ON SATURDAY.
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&& .AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
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***HIGH IMPACT EVENT TODAY*** A WARM FRONTAL BOUNDARY WAS JUST SOUTH OF LONG ISLAND AND THROUGH CENTRAL NEW JERSEY. THE WARM FRONT WILL LIKELY MOVE THROUGH LONG ISLAND AND INTO COASTAL CONNECTICUT AND REMAIN HUNG UP ACROSS CENTRAL NEW JERSEY INTO THIS EVENING. MEANWHILE A COLD FRONT THROUGH OHIO...KENTUCKY AND TENNESSEE WILL BE APPROACHING THIS EVENING. THE COLD FRONT CROSSES THROUGH THE AREA FROM AROUND 10Z TO 15Z THURSDAY. CONDITIONS REMAIN IFR TO LIFR UNTIL THE COLD FRONTAL PASSAGE. THERE COULD BE A PERIOD OF VLIFR AT A FEW LOCATIONS THIS EVENING. CONDITIONS IMPROVE QUICKLY TO VFR WITH THE RAIN ENDING AS THE FRONT MOVES THROUGH. THE RAIN WILL BE GENERALLY LIGHT TO MODERATE AT THE TERMINALS AFTER 22Z. HEAVY RAIN WAS MOVING NORTHEAST ACROSS LONG ISLAND AND INTO SOUTHERN CONNECTICUT AT 20Z. WIND WILL BE EAST TO SOUTHEAST 10 TO 15 MPH THROUGH THE DAY. A LOW LEVEL JET STREAM OF 40 TO 55 KT WAS ACROSS THE REGION...SO WILL CONTINUE WITH LOW LEVEL WIND SHEAR UNTIL THE COLD FRONTAL PASSAGE. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .THU...VFR. WESTERLY WIND 15-20G30-35KT. CHANCE OCCASIONAL GUSTS 35-40KT. .THU NIGHT...VFR. WIND AND GUSTS DIMINISHING. .FRI-SAT...VFR. .SUN...MARGINAL VFR. CHANCE OF RAIN AND SNOW. .MON...VFR.
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&& .MARINE...
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WINDS INCREASE ON ALL WATERS TO SCA LEVELS TONIGHT. SCA LEVEL SEAS ON THE COASTAL OCEAN WATERS IN EFFECT WITH GUSTS TO GALE FORCE LIKELY DEVELOPING CHRISTMAS MORNING AND CONTINUING INTO EARLY EVENING. SCA GUSTS THEN EXPECTED FOR THE REMAINDER OF THE EVENING...TAPERING OFF TO BELOW SCA LEVELS AFTER MIDNIGHT. SUB-SCA CONDITIONS ARE ANTICIPATED ON FRIDAY INTO NEXT WEEK THOUGH THERE IS UNCERTAINTY IN HOW FAR SOUTH THE STALLED FRONTAL BOUNDARY WILL REMAIN NEXT WEEK.
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&& .HYDROLOGY...
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UP TO THREE QUARTERS OF AN INCH OF RAINFALL HAVE FALLEN ACROSS THE HYDROLOGIC SERVICE AREA...AND AN ADDITION ONE TO ONE AND A HALF INCHES IS EXPECTED THROUGH CHRISTMAS MORNING. THE MAIN THREAT FROM THIS IS MINOR URBAN AND POOR DRAINAGE FLOODING LIKELY. DRY FRI-SATURDAY NIGHT. LIGHT PCPN IS POSSIBLE ON SUNDAY WITH THE PASSAGE OF A COLD FRONT. AT THIS TIME...THE FRONT IS EXPECTED TO STALL WELL TO OUR SOUTH LEAVING NEXT WEEK BASICALLY DRY...THOUGH THERE IS UNCERTAINTY ON HOW FAR SOUTH THE FRONT WILL STALL.
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&& .CLIMATE...
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RECORD MAXIMUM MINIMUMS FOR CHRISTMAS DAY... LOCATION.......RECORD/YEAR NEWARK.............47/1979 BDRIDGEPORT........45/1964 CENTRAL PARK.......50/1979 LAGUARDIA..........48/1964 JFK AIRPORT........46/1987 ISLIP AIRPORT......45/1987 THESE RECORDS LIKELY WILL NOT FALL AS TEMPERATURES ARE CURRENTLY FORECAST TO FALL TO AROUND 40 DEGREES AT OR BEFORE 11:59 PM ON THE 25TH.
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&& .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ330-335- 338-340-345. GALE WARNING FROM 6 AM TO 7 PM EST THURSDAY FOR ANZ330-335-338- 340-345-350-353-355. SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ350-353- 355.
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&& $$

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