Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 230543 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1243 AM EST TUE DEC 23 2014 .SYNOPSIS... LOW PRESSURE OFF CAPE HATTERAS WILL DRIFT SLOWLY NORTH OFF THE DELMARVA COAST TONIGHT...THEN PASS JUST SOUTHEAST OF LONG ISLAND LATER TUESDAY INTO TUESDAY NIGHT. A MORE SIGNIFICANT STORM SYSTEM WILL AFFECT THE AREA WEDNESDAY THROUGH CHRISTMAS MORNING...WITH A COLD FRONT PASSING THROUGH DURING CHRISTMAS MORNING. HIGH PRESSURE WILL BUILD IN FROM LATE THURSDAY THROUGH FRIDAY. A WEAK LOW PRESSURE TROUGH WILL MOVE THROUGH ON SATURDAY. ANOTHER LOW WILL APPROACH FROM THE SOUTH SATURDAY NIGHT INTO SUNDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... PERIODS OF RAIN AND DRIZZLE ON TAP THROUGH THE OVERNIGHT PERIOD. IT WILL NOT RAIN CONTINUOUSLY...BUT THERE WILL BE WAVES OF RAIN THROUGH THE OVERNIGHT...AND DRIZZLE OTHERWISE. LOWS TONIGHT WILL BE IN THE MID/UPPER 30S ELSEWHERE INLAND...AND IN THE LOWER 40S IN NYC METRO AND ALONG THE COAST. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... THE LOW WILL WEAKEN AS IT SLIDES JUST TO THE SE OF LONG ISLAND ON TUE. ITS OVERRUNNING PRECIP SHOULD ALSO PASS TO THE NE...LEAVING CLOUDY SKIES AND STILL CHANCES FOR SOME LIGHT RAIN MOST OF THE DAY TUE INTO TUE EVENING. LIKELY POP EXPECTED LATE TUE NIGHT AS DEEP LAYER SW FLOW DEVELOPS AND ANOTHER WARM FRONT APPROACHES AND REMAINS JUST TO THE SOUTH. HIGHS TEMPS SHOULD BE NEAR 50 ACROSS NYC METRO AND LONG ISLAND...AND IN THE MID/UPPER 40S ELSEWHERE...THEN DROPPING INTO THE MID/UPPER 30S INLAND AND LOWER/MID 40S FOR NYC METRO AND COASTAL SECTIONS TUE NIGHT AS A WARM FRONT REMAINS JUST TO THE SOUTH. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... FORECAST FOR THE MOST PART REMAINS CONSISTENT PAST COUPLE DAYS...ONLY CHANGE IS A LITTLE LATER COLD FRONTAL PASSAGE AND RAIN LINGERING INTO CHRISTMAS MORNING ACROSS THE EASTERN ZONES AS UPPER TROUGH BECOMES MORE NEGATIVE AND THE UPPER LOW CLOSES OFF WEDNESDAY NIGHT. BOTH THE GFS AND ECMWF HANDLE THE SYSTEM WELL WITH THE NAM NOT AS DEEP AND SLOWER THAN THE OTHER GUIDANCE. THE LOW LEVEL JET IS ALSO A LITTLE WEAKER THAN DURING THE PAST FEW RUNS...NOW AROUND 50 KT. THE LOW LEVEL JET WILL STILL PROVIDE SIGNIFICANT LIFT WEDNESDAY AFTERNOON AND EVENING FOR PERIODS OF HEAVY RAINFALL. THE AREA STILL DOES NOT BECOME WARM SECTORED AS THE WARM FRONT REMAINS TO THE SOUTH. SO WILL NOT BE MENTIONING ANY CONVECTION. STRONG COLD ADVECTION SETS UP BEHIND THE COLD FRONT THURSDAY MORNING AND CONTINUES INTO THE EVENING...WEAKENING 00Z TO 06Z FRIDAY. WIND AND GUSTS REMAIN BELOW ADVISORY LEVELS THURSDAY. HIGH PRESSURE BUILDS IN FRIDAY. AGAIN...CONSISTENCY REMAINS WITH THE WEAKENING TROUGH AND DRY COLD FRONTAL PASSAGE SATURDAY. IN THE SOUTHERN STREAM A WAVE DEVELOPS ON THE FRONTAL BOUNDARY AND TRACKS NORTH SATURDAY NIGHT INTO SUNDAY. SOME DIFFERENCES IN GUIDANCE AS THIS WAVE WILL BE COMING INTO THE PACIFIC NORTHWEST WEDNESDAY NIGHT AND MAY NOT BE INITIALIZED WELL. SO FROM SATURDAY THROUGH MONDAY GENERALLY FOLLOWED WPC GUIDANCE. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... WEAK LOW PRESSURE APPROACHES...REACHING JUST SOUTH OF LONG ISLAND BY LATE THIS AFTN. EASTERLY FLOW WITH WIDESPREAD IFR CONDITIONS AND LIGHT RAIN AND/OR DRIZZLE. THERE IS THE POSSIBILITY OF A LULL DURING TUE AFTN/EVE WITH JUST DRIZZLE. STEADIER RAIN RETURNS LATE TUES NIGHT. NE-E WINDS 5 TO 15 KT TODAY...STRONGEST NEAR THE COAST. WIND DIRECTIONS UNCERTAIN AFT 16Z WHICH WILL DEPEND ON LOCATION AND TRACK OF WEAK LOW S OF LONG ISLAND. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY... .TUE NIGHT...IFR/LIFR. RAIN. .WED-WED NIGHT...HIGH IMPACT EVENT LIKELY. IFR WITH OCNL +RA. S/SE WINDS 15-20G20-25KT POSSIBLE. LLWS PROBABLE SOUTHERN AND EASTERN TERMINALS. WINDS SHIFT TO THE SW LATE AT NIGHT. .THU-THU NIGHT...IMPROVING TO VFR IN THE MORNING FROM W TO E. WSW-NW WINDS G30-35+KT LIKELY. .FRI...VFR. WNW WINDS G20-25KT POSSIBLE. .SAT...VFR. SW WINDS G20 KT. && .MARINE... SCA CONDS ON TAP FOR ALL OCEAN WATERS. AS THE LOW PASSES CLOSE BY ON TUE...WINDS AND SEAS SHOULD SUBSIDE...WITH ONLY LINGERING 5-FT SEAS E OF MORICHES THROUGH THE DAY ON TUE....AND POSSIBLY INTO EARLY TUE EVENING. AN INCREASING SE TO S FLOW AHEAD OF AN APPROACHING COLD FRONT WILL ALLOW FOR SEAS TO BUILD ON THE OCEAN WATERS WED INTO WED NIGHT. IN ADDITION...SOME GUSTS ACROSS THE FORECAST OCEAN WATERS MAY INCREASE TO SMALL CRAFT LEVELS WEDNESDAY NIGHT. A COLD FRONT CROSSES THE WATERS FROM AROUND 12Z TO 18Z THURSDAY. THE SOUTHERLY WIND SHIFTS TO THE WEST TO NORTHWEST IN THE COLDER AIR. WIND GUSTS WILL CONTINUE TO INCREASE AND LIKELY REACH GALE FORCE LEVELS ACROSS ALL THE FORECAST WATERS BY MIDDAY THURSDAY. THEN AS HIGH PRESSURE BUILDS IN FROM THE SOUTH AND COLD ADVECTION WEAKENS WIND AND GUSTS WILL DIMINISH THURSDAY EVENING INTO LATE THURSDAY NIGHT...FALLING BELOW EVEN SMALL CRAFT LEVELS BY FRIDAY MORNING. THE THE WESTERLY FLOW THURSDAY INTO FRIDAY SEAS ON THE OCEAN WATERS WILL BE SLOWLY SUBSIDING...FALLING BELOW 5 FT BY LATE FRIDAY. AS HIGH PRESSURE WEAKENS FRIDAY NIGHT AND A TROUGH APPROACHES SATURDAY...SOUTHWESTERLY WIND WILL INCREASE. GUSTS ARE EXPECTED TO REMAIN BELOW 25 KT...HOWEVER SEAS ON THE OCEAN WATERS WILL LIKELY BUILD BACK UP TO SMALL CRAFT LEVELS LATE FRIDAY NIGHT INTO SATURDAY. THEN SUBSIDE ONCE AGAIN SUNDAY AS LOW PRESSURE MOVES INTO THE WATERS AND THE PRESSURE GRADIENT WEAKENS. && .HYDROLOGY... BASIN AVG RAINFALL OF 1/2 TO 3/4 INCH EXPECTED THROUGH TUE NIGHT...THEN ANOTHER 1 TO 1 1/2 INCHES WITH LOCALLY HIGHER AMTS EXPECTED WED INTO THU MORNING...WITH TOTAL RAINFALL OF 1 1/2 TO 2 INCHES WITH LOCALLY HIGHER AMOUNTS. MINOR URBAN AND POOR DRAINAGE FLOODING IS POSSIBLE. UP TO AN INCH OF LIQUID EQUIVALENT QPF POSSIBLE SAT NIGHT INTO SUNDAY NIGHT. && .TIDES/COASTAL FLOODING... STORM SURGE A LITTLE OVER 1 FT EXPECTED VIA A STRENGTHENING E FLOW BETWEEN DEPARTING HIGH PRESSURE AND A WEAK LOW DRIFTING UP FROM THE SOUTH. THIS COULD BRING WATER LEVELS CLOSE TO OR JUST OVER MINOR COASTAL FLOOD THRESHOLDS WITH THE HIGH TIDE CYCLE DURING MID TO LATE TUE MORNING...ON THE WESTERN SOUND...THE SOUTH SHORE BAYS OF WESTERN LONG ISLAND...AND POSSIBLY IN PECONIC BAY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ353-355. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ350. && $$ SYNOPSIS...JMC/GOODMAN/MET NEAR TERM...MPS SHORT TERM...GOODMAN LONG TERM...MET AVIATION...JC MARINE...GOODMAN/MET HYDROLOGY...GOODMAN/MET TIDES/COASTAL FLOODING...

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