Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 240009 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 709 PM EST SUN NOV 23 2014 .SYNOPSIS... A PERIOD OF STORMY WEATHER WILL KICK OFF LATE TONIGHT AS LOW PRES RAPIDLY DEEPENS OVER THE GREAT LAKES AND DRAWS A WARM FRONT THRU THE TRI-STATE REGION. A COLD FRONT WILL FOLLOW ON MON NGT. A WEAK COLD FRONT PASSES THROUGH ON TUESDAY...WITH HIGH PRESSURE BRIEFLY BUILDING INTO THE THE REGION TUESDAY NIGHT. COASTAL LOW PRESSURE IMPACTS THE REGION WEDNESDAY INTO WEDNESDAY NIGHT...DEPARTING INTO THE CANADIAN MARITIMES ON THURSDAY. HIGH PRESSURE THEN BUILDS IN FROM THE WEST INTO FRIDAY...WITH A ALBERTA CLIPPER SYSTEM POSSIBLE TO IMPACT THE AREA SATURDAY. && .NEAR TERM /THROUGH MONDAY/... JUST SOME MINOR TWEAKS TO TIMING OF ONSET OF RAIN AFT MIDNIGHT INTO MON MRNG...WITH MAINLY A FEW SHWRS THEREAFTER FOR MOST OF MON. PCPN AMTS AROUND AN INCH. AN EMBEDDED TSTM IS POSSIBLE ACROSS SOUTHERN PORTIONS OF THE TRI-STATE LATE TONIGHT INTO EARLY MON MORNING AS A TONGUE OF ELEVATED INSTABILITY ACCOMPANIES LLJ IN THE MORNING. THE HEAVIEST RAIN DOES LOOK TO FALL NEAR THE MRNG RUSH SO IMPACTS SHOULD BE EXPECTED. BY 12Z MON...THE CWA WILL BE SANDWICHED BETWEEN A 970S LOW OVER THE UPR GREAT LAKES...AND A 1030S HIGH OVER THE ATLANTIC. THIS WILL TRANSLATE INTO STRONG SLY FLOW. THE GFS HAS H975 WINDS OVER 50KT FOR MOST OF LI...WHICH IS CONCERNING. HAVE MIXED DOWN 80 PERCENT OF THIS FOR THE FCST AND ISSUED A WIND ADVY FOR ALL OF LI...INCLUDING BROOKLYN AND QUEENS. THERE IS THE POTENTIAL THAT THE ADVY MAY NEED TO BE EXPANDED NWD INTO CSTL CT IF DEEPER MIXING OCCURS. THE CORE OF THE STRONGEST WINDS ALOFT SHIFT EWD THRU THE DAY...SO ONLY KEPT THE WRN PORTION OF THE ADVY THRU THE MRNG. SOME UNCERTAINTY ON WHETHER WIND ADVISORY GUSTS WILL CONTINUE IN SUFFOLK COUNTY INTO THE AFTERNOON...BUT WILL LET MIDSHIFT RE- EVALUATE. OTHERWISE...GUSTS TO 40 MPH POSSIBLE ACROSS NE NJ AND LOWER HUDSON VALLEY AND HIGHER ELEVATIONS IN THE AFTERNOON WITH ANY BREAKS OF SUN AND DEEPER MIXED LAYER. RECORD HIGH TEMPS STILL POSSIBLE. && .SHORT TERM /MONDAY NIGHT/... THE ASSOCIATED CDFNT COMES THRU OVERNIGHT. THIS USHERS THE MORE HUMID AIRMASS OFFSHORE. THE PRES GRAD STILL STAYS UP SO IT WILL REMAIN WINDY THRU THE NGT. SPEEDS HOWEVER WILL REMAIN BLW ADVY CRITERIA WITH THE LOW APPROACHING LABRADOR. A FEW SHWRS ARE POSSIBLE WITH THE FROPA. THE NAM HAS BEEN VERY CONSISTENT WITH THIS SUGGESTION. AS A RESULT...MAINTAINED LOW CHCS FOR SHWRS FOR THE PERIOD. WITH THE COLD AIR LAGGING BEHIND AND WINDS KEEPING THE LLVLS MIXED...LOW TEMPS EXPECTED TO BE A SOLID 10 DEGREES OR MORE ABV AVG. && .LONG TERM /TUESDAY THROUGH SUNDAY/... TRANQUIL AND NEAR SEASONABLE TEMPS ON TUES AS A WEAK COLD FRONT PASSES THROUGH THE REGION AND HIGH PRESSURE BRIEFLY BUILDS IN ITS WAKE TUES NIGHT. POTENTIAL CONTINUES TO INCREASE FOR A COASTAL STORM WITH SNOW...RAIN AND WIND TO IMPACT THE REGION WED/WED NIGHT...BUT SPREAD REMAINS MODERATE IN TERMS OF EXACT TRACK OF THIS SYSTEM. FORECAST SENSITIVITY BASED ON SBU CSTAR ANALYSIS FOR THIS SYSTEM LIES IN DEVELOPMENT OF TROUGH OVER THE EPAC OVER THE NEXT 48 HRS...AND RESULTANT DOWNSTREAM STRENGTH OF WEST COAST RIDGING AND ULTIMATELY STRENGTH OF EAST COAST TROUGHING FOR MIDWEEK. OPERATIONAL/ENSEMBLE MODEL ANALYSIS REVEAL MID/UPPER LEVEL MODEL FIELDS IN GOOD AGREEMENT OVER THE NEXT 48 HOURS INITIALLY WITH PHASING NORTHERN STREAM AND PAC ENERGY DIVING DOWN THE BACKSIDE OF DEEP CENTRAL US TROUGHING...WITH THIS ENERGY THEN SWINGING UP THE COAST WED AND INTERACTING WITH YET ANOTHER PIECE OF NORTHERN STREAM SHORTWAVE ENERGY DIVING THROUGH THE MID-MISSISSIPPI RIVER VALLEY. IT IS WITH THIS SECOND INTERACTION...AFTER 48 HRS...THAT MODELS DIVERGE ENOUGH TO AFFECT STRENGTH AND ORIENTATION OF THE PHASED SHORTWAVE ENERGIES AS THEY PIVOT THROUGH THE NE WED NIGHT/EARLY THU. THIS IS RESULTING IN MINOR TIMING DIFFERENCES WITH THE COASTAL LOW...BUT MAINLY TRACK DIFFERENCES. THE RANGE OF OPERATIONAL SOLUTIONS ON TRACK OF COASTAL LOW ARE...THE 12Z ECMWF CONTINUING TO TREND WEST AND TRACKING ACROSS LI WED NIGHT...TO THE 12Z NAM/CMC TRENDING WEST AND PROJECTING WELL EAST OF BENCHMARK...AND 12Z GFS CONSISTENTLY NEAR THE 40/70 LAT/LON. WITH THIS SPREAD HAVE CONTINUED TO PLAY A MIDDLE OF THE ROAD TRACK BETWEEN CMC/GEFS/ECMWF ENSEMBLE MEANS...WHICH WOULD TRACK LOW PRESSURE NEAR TO JUST INSIDE THE 40/70 LAT/LON BENCHMARK WED NIGHT. WITH ONLY A MARGINALLY COLD AIRMASS TO START...THIS TRACK WOULD BRING MAINLY RAIN TO LI/SE CT...RAIN/SNOW MIX FOR NYC/NJ METRO AND SW CT...AND MAINLY SNOW WELL N&W OF NYC...CHANGING TO ALL SNOW WED NIGHT FOR MOST IF NOT ALL OF THE REGION AS THE LOW DEEPENS AND TRACK NORTH. THIS MESHES FAIRLY WELL WITH WPC...WITH A LOW PROBABILITY OF SEEING WARNING LEVEL SNOW RELEGATED TO INTERIOR PORTIONS OF NE NJ...LOWER HUDSON VALLEY..AND SW CT...AND ADVISORY LEVEL SNOW POSSIBLE INTO NYC METRO AND COASTAL SW CT SUN NIGHT. CONFIDENCE IN THESE VALUES IS LOW TO MODERATE AT THIS POINT BASED ON ABOVE MENTIONED SPREAD. PREDICTABILITY TOO LOW WITH THIS DAY 4 EVENT FOR A DETERMINISTIC STORM TOTAL SNOW FORECAST. ZONAL FLOW BUILDS IN BEHIND THE SYSTEM FOR FRI INTO THE WEEKEND WITH GENERALLY QUIET AND TEMPS A FEW DEGREES SEASONABLE. A WEAK ALBERTA CLIPPER MAY PASS TO THE NORTH ON SATURDAY WITH A FEW RAIN/SNOW SHOWERS. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... HIGH PRESSURE DEPARTS TO THE EAST AS A WARM FRONT APPROACHES TONIGHT. VFR THROUGH AROUND 03-05Z TONIGHT. RAIN WITH IFR CIGS/VSBY DEVELOPS SHORTLY THEREAFTER. LIFR AT TIMES IN RAIN POSSIBLE 9-14Z. CANNOT RULE OUT THUNDER AROUND THIS TIME FRAME AS WELL... ESPECIALLY EAST OF NYC METRO. IFR CONDITIONS LIKELY LINGER THROUGH THE MORNING MONDAY...ALTHOUGH THE MODERATE/HEAVY RAIN WILL TAPER OFF TO LIGHT ISOLATED SHOWERS. LIGHT S WINDS INTO THE EVENING TURN TOWARD THE SE. LOW LEVEL WIND SHEAR IS LIKELY LATE TONIGHT INTO EARLY MONDAY MORNING WITH WINDS AT 2000FT RANGING FROM 50-65 KT. SURFACE WINDS TURN BACK TO THE SOUTH/SOUTHWEST BY 10-13Z. SPEEDS INCREASE QUICKLY TO 15 TO 25KT WITH GUSTS 25 TO 35 KT. A FEW COASTAL GUSTS COULD REACH 40 KT. .OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT...VFR. WINDS SHIFT TO THE WEST AT 10-15 KT. .TUESDAY...VFR. WSW WINDS 15-20 KT WITH 20-30 KT GUSTS. .TUESDAY NIGHT...DIMINISHING WINDS. SUB-VFR CIGS POSSIBLE LATE. .WEDNESDAY-WEDNESDAY NIGHT...LOW TO MODERATE CONFIDENCE FORECAST WITH PASSAGE OF COASTAL LOW. ACCUMULATING SNOW THREAT POSSIBLE FOR THE INTERIOR...BUT ACCUMULATING SNOW COULD OCCUR CLOSER TO THE COAST DURING WED NIGHT BASED ON TRACK OF LOW. STRONG WINDS POSSIBLE DEPENDING ON TRACK OF LOW AS WELL. .THURSDAY...BECOMING VFR. LINGERING RAIN/SNOW SHOWERS POSSIBLE EARLY. GUSTY WINDS POSSIBLE AS WELL. .FRIDAY...VFR WITH GUSTY NW WINDS. && .MARINE... STRONG PRES GRAD SETS UP LATE TNGT ALLOWING FOR SLY FLOW THRU MON NGT. GALES DEVELOP LATE TNGT AND CONTINUE THRU MON. WINDS DIMINISH LATE MON NGT FROM W TO E. THE GALE WAS EXTENDED FOR THE ERN WATERS...AND MAY NEED TO BE EXTENDED FOR THE REMAINING WATERS BASED ON THE EXACT TIMING AND STRENGTH OF THE SYS. SCA CONDITIONS CONTINUE THROUGH TUESDAY WITH A TIGHT WNW GRADIENT...FOLLOWED BY A RELATIVELY BRIEF PERIOD OF SUB-SCA CONDITIONS LIKELY TUE NIGHT THROUGH WEDNESDAY MORNING AS HIGH PRESSURE NOSE IN. SCA CONDITIONS THEN LIKELY WED AFT THRU THU AS A COASTAL STORM AFFECTS THE WATERS. POTENTIAL EXISTS FOR MARGINAL GALE CONDS ON THE EASTERN WATERS WED NIGHT AS LOW PRESSURE MAKES ITS CLOSEST APPROACH TO THE REGION. SCA CONDS POSSIBLE ON THE OCEAN WATERS THROUGH FRIDAY DUE TO RESIDUAL SWELLS AND TIGHT OFFSHORE GRADIENT. && .HYDROLOGY... AROUND AN INCH OF RAIN IS EXPECTED LATE TNGT INTO MON. MINOR URBAN FLOODING WILL BE POSSIBLE...WITH IMPACTS LIKELY AROUND THE TIME OF THE MRNG COMMUTE. INCREASING POTENTIAL EXISTS FOR 1/2 TO 1 INCH OF PRECIPITATION WED INTO WED NIGHT. SOME PORTION OF THIS SHOULD FALL IN THE FORM OF SNOW...PARTICULARLY ACROSS AREAS N&W OF THE NYC METRO. && .TIDES/COASTAL FLOODING... SOME OF THE MOST VULNERABLE SPOTS ALONG THE SOUTH SHORE OF WESTERN LI...NYC...AND SOUTHWESTERN CT COULD SEE MINOR INUNDATION DURING THE MON MRNG CYCLE. SOME MINOR BEACH EROSION IS ALSO POSSIBLE ON THE ATLANTIC COAST WITH SURF IN THE 6-8FT RANGE. && .CLIMATE... RECORD HIGH TEMPERATURES FOR MONDAY 24 NOVEMBER... LOCATION........RECORD/YEAR.....FORECAST HIGH NEWARK..............75/1979..........71 BRIDGEPORT..........63/1979..........65 CENTRAL PARK........73/1979..........69 LAGUARDIA AIRPORT...68/1999..........70 JFK AIRPORT.........63/2001*.........68 ISLIP...............63/2001..........66 * ALSO OCCURRED IN PREVIOUS YEARS && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...WIND ADVISORY FROM 4 AM TO 11 AM EST MONDAY FOR NYZ075-176>179. WIND ADVISORY FROM 4 AM TO 6 PM EST MONDAY FOR NYZ078>081. NJ...NONE. MARINE...GALE WARNING FROM 1 AM TO 6 PM EST MONDAY FOR ANZ330-335-338- 340-345. GALE WARNING FROM 1 AM MONDAY TO 6 AM EST TUESDAY FOR ANZ350- 353-355. && $$ SYNOPSIS...JMC/NV NEAR TERM...JMC/NV SHORT TERM...JMC LONG TERM...NV AVIATION...MPS MARINE...JMC/NV HYDROLOGY...JMC/NV TIDES/COASTAL FLOODING... CLIMATE...

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