Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 231514 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1014 AM EST TUE DEC 23 2014 .SYNOPSIS... A WEAK AREA OF LOW PRESSURE TRACKS JUST TO THE SOUTH AND EAST OF LONG ISLAND THROUGH TONIGHT. A STRONGER STORM SYSTEM WILL IMPACT THE REGION CHRISTMAS EVE THROUGH CHRISTMAS MORNING. A COLD FRONT WILL MOVE ACROSS THE REGION CHRISTMAS DAY. HIGH PRESSURE BUILDS TO THE SOUTH THURSDAY NIGHT THROUGH SATURDAY. A COLD FRONT APPROACHES FROM THE NORTHWEST SATURDAY NIGHT...THEN PUSHES TO THE SOUTH SUNDAY. THIS FRONT THEN STALLS OUT SOUTH OF THE AREA...WITH WAVES OF LOW PRESSURE RIDING ALONG IT INTO EARLY NEXT WEEK...AS CANADIAN HIGH PRESSURE BUILDS IN TO THE NORTH. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... ISENTROPIC LIFT GRADUALLY WEAKENS THROUGH THE DAY...WITH WIDESPREAD SHOWER ACTIVITY TRANSITIONING TO SPOTTY LIGHT AND DRIZZLE THIS AFTERNOON FROM SW TO NE. SOUTHERLY LOW LEVEL FLOW WILL USHER A MILD AIRMASS INTO THE REGION WITH HIGH TEMPS RANGING FROM THE LOW TO MID 40S ACROSS THE INTERIOR TO THE LOW 50S ALONG THE COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... LOW PRES PASSES OVER MONTAUK POINT THIS EVENING. WILL KEEP CHANCE POPS IN THE FORECAST FOR THIS EVENING AS THERE WILL BE WEAK LIFT ALONG WITH ABUNDANT LOW LEVEL MOISTURE...AND NOT EXPECTING WIDESPREAD RAINFALL UNTIL LATER TONIGHT. DEEP UPPER TROUGH AND SFC LOW PRES DIGS INTO THE MIDWEST. SEVERAL SHORTWAVES AHEAD OF THE MAIN SYSTEM WILL ENHANCE RAINFALL OVER THE REGION BY WEDNESDAY MORNING. THE MAIN LOW TRACKS TO THE NORTH INTO CANADA AS AN OPEN WAVE DEVELOPS OVER THE SOUTHEAST U.S. THAT WAVE MOVES ALONG THE COAST ON CHRISTMAS EVE AND MOVES ACROSS THE REGION WEDNESDAY NIGHT. 50-60 KT LOW LEVEL JET WILL MOVE INTO THE REGION IN THE AFTERNOON AND AT NIGHT...AND PRECIPITABLE WATERS ACROSS THE REGION WILL RANGE FROM 1.5-2"...WHICH IS EXCEEDINGLY HIGH FOR THIS TIME OF YEAR. MODERATE TO HEAVY RAIN EXPECTED WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. WITH ML MOST UNSTABLE CAPE OF 200-300 J/KG ACROSS SOUTHERN ZONES...WILL ADD ISOLATED THUNDERSTORMS IN THE FORECAST FOR WEDNESDAY AFTERNOON. RAIN GRADUALLY TAPERS OFF FROM WEST TO EAST CHRISTMAS MORNING AS COLD FRONT MOVES ACROSS THE REGION. PRES GRADIENT TIGHTENS CHRISTMAS AFTERNOON...AND STRONG WESTERLY WINDS WILL DEVELOP...RANGING FROM 15-20 MPH WITH 25-35 MPH GUSTS. THE DIURNAL RANGE THROUGH THE PERIOD WILL GENERALLY RANGE FROM THE 40S AT NIGHT TO THE 50S DURING THE DAY. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... DEEP LAYERED RIDGING BEGINS TO PUSH OUTER PERIPHERY OF CLOSED LOW OVER THE CANADIAN MARITIMES TO THE NE THURSDAY NIGHT...ALLOWING FOR CONTINUED CLEARING...ESPECIALLY OVER EASTERN ZONES. LOWS THURSDAY NIGHT WERE BASED ON A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WITH NAM 2-METER TEMPERATURES...WITH VALUES 5-10 DEGREES ABOVE NORMAL. DEEP LAYERED RIDGING BUILDS OVER THE AREA FRIDAY...WITH ITS AXIS PASSING TO THE EAST FRIDAY NIGHT...FOLLOWED BY SW FLOW ALOFT ON SATURDAY. SHOULD BE SUFFICIENT SUBSIDENCE WITH/IN THE VICINITY OF THE RIDGE TO KEEP THINGS DRY WITH MINIMAL CLOUD COVER IN THIS TIME FRAME AS A RESULT. THE GFS IS AN OUTLIER COMPARED TO THE ECMWF/CMC/ITS ENSEMBLE MEAN WITH HOW PROGRESSIVE IT IS WITH THE COLD FRONTAL PASSAGE FOR THE LATTER HALF OF THE WEEKEND...AND ALSO HOW FAR OFFSHORE THE FRONT STALLS OUT. AS A RESULT...BASED FORECAST SATURDAY NIGHT-MONDAY ON A BLEND OF THE ECMWF/CMC/GEFS MEAN. BASED ON THIS BLEND...SATURDAY NIGHT SHOULD BE DRY WITH NO SIGNIFICANT FORCING PROGGED...THEN HAVE A CHANCE FOR SOME -SHRA ACROSS SOUTHERN ZONES AND SOME -SHRA/-SHSN ACROSS NORTHERN ZONES WITH THE COLD FRONTAL PASSAGE SUNDAY. FOR NOW GOING WITH CHANCE POPS SUNDAY NIGHT AND SLIGHT CHANCE POPS MONDAY TO REFLECT POTENTIAL WAVES OF LOW PRESSURE PASSING TO THE S...WITH MAINLY SNOW EXPECTED ACROSS N ZONES...AND RAIN CHANGING TO SNOW ACROSS S ZONES. STILL QUITE A BIT OF UNCERTAINTY ON EXACT TIMING/STRENGTH/TRACK AND NUMBER OF THESE WAVES. FOR NOW BEST TO CHARACTERIZE WEATHER FOR EARLY NEXT WEEK AS POTENTIALLY UNSETTLED...WITH A BETTER CHANCE FOR SNOW THAN RAIN AT MOST LOCATIONS...IF ANY THING FALLS AT ALL. GIVEN LARGE DEGREE OF UNCERTAINTY...IT IS TO EARLY TO SPECULATE ON WHAT...IF ANY IMPACT THERE WILL BE FROM THESE POTENTIALLY MULTIPLE COASTAL LOWS PASSING TO THE S. FOR TEMPERATURES FRIDAY-MONDAY USED A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE. TEMPERATURES WILL BE WELL ABOVE NORMAL FRIDAY-SATURDAY NIGHT. IF ECMWF/CMC ARE CORRECT...COULD END UP 5 TO POSSIBLY 10 DEGREES WARMER THAN CURRENTLY FORECAST - GIVEN WELL MIXED LOW LEVELS AND 850 TEMPERATURES FORECAST OF 6 TO 8C. SUNDAY/SUNDAY NIGHT SHOULD FEATURE TEMPERATURES SLIGHTLY ABOVE NORMAL...THEN BELOW NORMAL TEMPERATURES ARE FORECAST FOR NOW ON MONDAY. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... WEAK LOW PRES APPROACHES...REACHING JUST SOUTH OF LONG ISLAND EARLY THIS EVENING. WINDS SHOULD REMAIN NORTHEAST...OR EVEN BACK TOWARD THE N/NE AS THE DAY PROGRESSES. SPEEDS 5 TO 15 KTS. MAINLY IFR CONDITIONS ARE ANTICIPATED. CHANCE MVFR THIS AFTERNOON...BUT CONFIDENCE IN THIS HAPPENING IS BECOME LOW. VSBYS MVFR...BUT BRIEF IFR POSSIBLE AT TIMES. PERIODS OF LIGHT RAIN AND DRIZZLE...PROBABLY BECOMING LESS FREQUENT LATE THIS AFTERNOON AND EVENING. CONDITIONS LIKELY REMAIN AT 1 KFT...OR LOWER FOR A GOOD PORTION OF THE DAY AT JFK...LGA AND EWR. AMENDMENTS LIKELY THROUGH THE DAY..SO PLEASE CHECK FOR THE LATEST TERMINAL FORECASTS. .OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY... .WED...IFR. RA. CHC +RA STARTING LATE MORNING. SE-S 10KT. LLWS AFTERNOON. .WED NIGHT...IFR. RA. CHC +RA. S 15-20G20-25KT. .THU...IMPROVING TO VFR IN THE MORNING. SHIFT W EARLY 20G30-35KT. CHANCE OCCASIONAL GUSTS 35-40KT. .THU NIGHT...VFR. W 15-20G30-35KT EVE...DIM 10KT BY LATE. .FRI...VFR. W 10KT. .SAT...VFR. SW 10KT. && .MARINE... SEAS ON THE OCEAN WILL RANGE FROM 6-9 FT TODAY AND TONIGHT. WITH WIND GUSTS TO AROUND 25 KT EXPECTED ON THE OCEAN/LI SOUND WATERS THIS MORNING. WINDS SUBSIDE THIS AFTERNOON INTO EVENING...BUT SCA OCEAN SEAS WILL REMAIN SMALL CRAFT ADVISORY THROUGH TONIGHT. BY WEDNESDAY AFTERNOON...SCA LEVEL WIND GUSTS WILL DEVELOP ON ALL WATERS ALONG WITH OCEAN SEAS BUILDING TO 5-7 FT AS LOW PRES MOVES NORTH THROUGH THE WATERS. A COLD FRONT PUSHES ACROSS THE WATERS THURSDAY MORNING. GRADIENT TIGHTENS...AND GALE FORCE WINDS GUSTS ARE POSSIBLE ON THE WATERS LATE THURSDAY. GUSTS TO GALE FORCE ARE LIKELY ON THE COASTAL OCEAN WATERS AND POSSIBLE ELSEWHERE THROUGH AT LEAST THURSDAY EVENING...AND POSSIBLY THROUGH THE NIGHT OVER THE EASTERN COASTAL OCEAN WATERS. WINDS AND SEAS FALL BELOW SCA LEVELS ON ALL WATERS BY FRIDAY MORNING AND REMAIN SO THROUGH SATURDAY. SEAS COULD POSSIBLY BUILD TO SCA LEVELS ON THE COASTAL OCEAN WATERS EAST OF MORICHES INLET LATE SATURDAY. && .HYDROLOGY... BASIN AVG RAINFALL OF 1/2 TO 3/4 INCH EXPECTED TODAY THROUGH TONIGHT. ANOTHER 1 TO 1 1/2 INCHES WITH LOCALLY HIGHER AMOUNTS WEDNESDAY THROUGH THURSDAY MORNING...WITH TOTAL RAINFALL OF 1 1/2 TO 2 1/4 INCHES WITH LOCALLY HIGHER AMOUNTS. MINOR URBAN AND POOR DRAINAGE FLOODING IS POSSIBLE. IT SHOULD BE DRY FROM LATE THURSDAY THROUGH AT LEAST SATURDAY EVENING. && .TIDES/COASTAL FLOODING... WATER LEVELS HAVE PEAKED AT OR JUST ABOVE MINOR FLOODING THRESHOLDS ALONG NY HARBOR AND SOUTH SHORE BAYS...AND WILL GRADUALLY SUBSIDE OVER THE NEXT COUPLE OF HOURS. TIDAL DEPARTURES OF 3/4 TO 1 1/4 FT WILL RESULT IN LOCALIZED MINOR COASTAL FLOODING ALONG THE WESTERN SOUND LATE THIS MORNING/EARLY AFTERNOON. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR ANZ330- 335-350-353-355. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM THIS AFTERNOON TO 6 AM EST WEDNESDAY FOR ANZ350-353-355. && $$ SYNOPSIS...MALOIT/MPS NEAR TERM...MALOIT/MPS SHORT TERM...MPS LONG TERM...MALOIT AVIATION...JC MARINE...MALOIT/MPS HYDROLOGY...MALOIT/MPS TIDES/COASTAL FLOODING...

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