Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 150438 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1238 AM EDT TUE APR 15 2014 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL APPROACH THE REGION THROUGH TUESDAY AND THEN MOVE ACROSS THE REGION TUESDAY EVENING. HIGH PRESSURE BUILDS IN FROM THE WEST WEDNESDAY...THEN REMAINS NORTH OF THE REGION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THE HIGH WEAKENS AND MOVES EAST FRIDAY...ALLOWING A LOW PRESSURE SYSTEM TO APPROACH FROM THE SOUTHWEST THIS WEEKEND. WEAK HIGH PRESSURE BUILDS IN FOR MONDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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PRECIPITATION A LITTLE SLOWER TO MOVE INTO THE REGION AS UPPER TROUGH REMAINS WELL TO THE WEST. HOWEVER TIMING STILL BRING RAIN INTO THE WESTERN SECTIONS BY MORNING AND WILL CONTINUE WITH LIKELY/CATEGORICAL POPS. FOG WAS JUST BEGINNING TO DEVELOP...MAINLY ALONG THE COAST. ALSO UPDATED TEMPERATURES AND DEW POINTS FOR CURRENT CONDITIONS. DEEP TROUGH OVER THE CENTRAL PLAINS PUSHES INTO THE MISSISSIPPI RIVER VALLEY TONIGHT...WHILE ASSOCIATED STRONG COLD FRONT WITH PRIMARY LOW PUSHES INTO WESTERN NY/PA OVERNIGHT. DEEP LAYERED MOISTURE INCREASES THROUGH THE OVERNIGHT WITH INCREASING CHANCE FOR SHOWERS LATE TONIGHT/EARLY TUE MORNING AS INCREASING FORCING/MOISTURE CONVERGENCE. PERSISTENT MOIST ONSHORE FLOW UNDER A STRONG INVERSION HAS LED TO THE DEVELOPMENT OF STRATUS. PATTERN FOR ADVECTION FOG AND DRIZZLE WILL INCREASE ALONG COASTAL AREAS OF CT/LI OVERNIGHT...BUT A STRONG LOW-LEVEL FLOW LEAVES SOME UNCERTAINTY ON HOW DENSE FOG WILL BECOME.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... MODELS IN GOOD AGREEMENT WITH THE STRONG AND DEEP NEUTRALLY TILTED UPPER TROUGH TROUGH SLIDING FROM THE MISSISSIPPI RIVER VALLEY TO APPALACHIANS ON TUESDAY...AND THEN NEGATIVELY TILTING THROUGH THE NE TUESDAY NIGHT. ITS ASSOCIATED COLD FRONT APPROACHING THE REGION IN THE AFTERNOON AND CROSSING IN THE EVENING. INCREASING CHANCE FOR RAIN TUESDAY MORNING INTO EARLY AFTERNOON WITH INCREASING LIFT AND MOISTURE CONVERGENCE AHEAD OF THE APPROACHING COLD FRONT. IN ADDITION...WITH A 65 TO 75 KT LOW LEVEL JET AHEAD OF THE COLD FRONT...WINDS WILL BE ON THE INCREASE IN THE MORNING INTO AFTERNOON. SUSTAINED WINDS OF 15 TO 25 MPH LIKELY...HIGHEST COAST...BUT AN INVERSION SHOULD LIMIT GUSTS MAINLY INTO THE 30S. ANY HEAVY RAIN MAY HAVE ENOUGH DOWNWARD MOMENTUM TO OVERCOME THE INVERSION AND BRING A HIGHER FRACTION OF THE LOW LEVEL JET TO THE SURFACE. WITH GULF MOISTURE TAP...INCREASING FORCING/MOISTURE CONVERGENCE MID MORNING INTO AFTERNOON...AND WEAK ELEVATED INSTABILITY...AREAS OF HEAVY RAIN AND EMBEDDED CONVECTION ARE POSSIBLE. SEE HYDROLOGY SECTION FOR MORE DETAILS ON RAINFALL AND ASSOCIATED IMPACTS. MAIN CONCERN FOR TUE AFT/EVE IS THAT MODELS HAVE BEEN FAIRLY CONSISTENT IN SIGNALING A SYNOPTICALLY FORCED SQUALL LINE TRAVERSING THE REGION IN THE AFTERNOON TO EARLY EVENING...WHICH WOULD HAVE POTENTIAL TO BRING DOWN GUSTS OF 50+ MPH. THIS WILL HAVE TO BE HANDLED BY SHORT FUSE ADVISORY/WARNING. STRONG COLD ADVECTION EXPECTED IN THE WAKE OF THE COLD FRONT TUE EVENING. WINDS OF 20 TO 30 MPH AND GUSTS 35 TO 45 MPH LIKELY TUESDAY NIGHT IN ITS WAKE. ADDITIONALLY...MODELS CONTINUE TO POINT TOWARDS A TRANSITION TO WINTRY PRECIP IN THE WAKE OF THE COLD FRONT BEFORE ENDING...PARTICULARLY ACROSS NW ZONES. WITH SHORTWAVE INSTABILITY COMING THROUGH...A BRIEF BURST OF MODERATE TO HEAVY SNOW IS NOT OUT OF THE QUESTION TUE EVENING N&W OF NYC. THIS POSES POTENTIAL FOR SOME LIGHT SNOW ACCUMULATION...AND WITH TEMPS FALLING INTO THE 20S SOME ICY ROAD CONDITIONS OVERNIGHT. LOW TEMPERATURES WILL BE NEAR OR BELOW FREEZING LATE TUESDAY NIGHT INTO VERY EARLY WEDNESDAY MORNING. WITH THE GROWING FOR THE ENTIRE COASTAL AREAS AND PORTIONS OF INTERIOR NE NJ/LOWER HUDSON VALLEY...THERE IS POTENTIAL THAT FREEZE CONDITIONS COULD BE MET FOR MUCH OF THIS AREA. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... THE BIG STORY DURING THIS PERIOD WILL BE THE TEMPERATURES...AS THEY WILL BE WELL BELOW NORMAL FOR THIS TIME OF YEAR...AND ESPECIALLY CONSIDERING HOW WARM IT HAS BEEN ACROSS THE AREA RECENTLY. WEDNESDAY WILL FEATURE STRONG COLD AIR ADVECTION AS HIGH PRESSURE CENTERED OVER THE OHIO VALLEY BUILDS IN. 850 TEMPERATURES ON WEDNESDAY WILL RANGE FROM AROUND -8C INLAND...TO -3C TO -6C ACROSS LONG ISLAND. THIS SHOULD TRANSLATE INTO TEMPERATURES IN THE MIDDLE TO UPPER 40S FOR MUCH OF THE AREA...WITH LOWER 50S POSSIBLE ACROSS THE NYC METRO AREA. THE CENTER OF HIGH PRESSURE WILL PASS WEST OF THE AREA ON WEDNESDAY...AND THEN TRACK TO THE NORTH AND EAST WEDNESDAY NIGHT. THIS WILL ALLOW A NORTHEASTERLY FLOW TO DEVELOP. WINDS INCREASE A BIT OVERNIGHT FOR EASTERN SECTIONS AS THE PRESSURE GRADIENT INCREASES IN RESPONSE TO THE HIGH PRESSURE STRENGTHENING OVER NEW ENGLAND. TEMPERATURES ON WEDNESDAY NIGHT WILL BE THE COLDEST DAY OF THE WEEK. WITH WINDS INCREASING OVERNIGHT...THEY WILL NOT BE AS COLD AS THEY COULD POTENTIALLY BE...ESPECIALLY ACROSS THE OUTLYING AREAS. WIDESPREAD LOWS BELOW FREEZING ARE EXPECTED ACROSS AREAS WELL INLAND. WHEREAS TEMPERATURES IN MIDDLE 30S ARE EXPECTED ACROSS NYC METRO AND COASTAL SECTIONS. IT IS POSSIBLE THAT SOME ISOLATED SPOTS MAY DIP TO FREEZING IN THESE AREAS. CONTINUED TO MENTION PATCHY FROST ACROSS ACROSS CERTAIN AREAS. THERE ARE SOME AREAS OF EASTERN LONG ISLAND THAT ARE FORECAST TO DROP BELOW FREEZING...BUT DID NOT MENTION FROST HERE AS WINDS OVERNIGHT PICK UP A BIT. QUIET CONDITIONS EXPECTED FOR THURSDAY AS HIGH PRESSURE CONTINUES TO SLOWLY PUSH TO THE NORTHEAST EAST. UPPER LEVEL RIDING THROUGH THE WEEKEND WILL GENERALLY MEAN A WARMING TREND AFTER WEDNESDAY. AN UPPER LEVEL TROUGH AND WEAK SURFACE LOW APPROACHES THE AREA FROM THE WEST FRIDAY NIGHT. ALSO...WEAK AREAS OF LOW PRESSURE WILL DEVELOP WELL SOUTH OF THE AREA ALONG THE FRONTAL BOUNDARY OFFSHORE AND HEAD NORTHEAST. 00Z ECMWF AND TO SOME EXTENT...THE 12Z GFS TRY TO PHASE THE NORTHERN AND SOUTHERN STREAM SYSTEMS. IN BOTH CASES...THE RESULTING COASTAL ARE TOO FAR OFFSHORE...AND ONLY LIGHT PRECIPITATION IS IN THE FORECAST. HIGH PRESSURE WILL BE IN CONTROL FOR THE BEGINNING OF THE WEEK. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... A STRONG COLD FRONT APPROACHES FROM THE WEST TONIGHT...THEN SLOWLY CROSSES THE TRI-STATE TUESDAY. CONDITIONS BEGINNING SLOW DETERIORATION TOWARDS IFR INTO THE OVERNIGHT HOURS. ALREADY IFR AT KISP...AND MVFR KGON. HAVE DELAYED ONSET OF MVFR THEN IFR AT REMAINDER OF TERMINALS BASED ON LATEST TRENDS. STILL EXPECT IFR TO HOLD OFF AT KSWF UNTIL 12Z. IFR SHOULD THEN CONTINUE THROUGH LATE TUESDAY AFTERNOON WEST...EARLY EVENING EAST. THERE IS SOME CHANCE OF LIFR/VLIFR ESPECIALLY AT COASTAL TERMINALS AND KHPN. LLWS TONIGHT AND TUESDAY ALL TERMINALS BUT KSWF WITH WINDS 50-65KT 1000-2000FT - DEPTH AND SPEED VARY BASED ON LOCATION. GUSTS HAVE BEGUN TO ABATE...AND WOULD EXPECT TO END AT ALL TERMINALS OVERNIGHT. FOR NOW CONTINUE TO BRING GUSTS BACK AROUND MID- MORNING - HOWEVER CONFIDENCE IN THIS IS ONLY MODERATE. ISOLATED TSRA POSSIBLE AT ALL TERMINALS MAINLY TUESDAY AFTERNOON - CONFIDENCE IN THIS AT ANY GIVEN LOCATION IS TOO LOW TO MENTION IN THE TAFS AT THIS TIME. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... .TUESDAY NIGHT...PERIOD OF -SN OR -SN/PL AS PRECIPITATION ENDS NW TERMINALS...WITH PERIOD -SNRA POSSIBLE REMAINDER. NW-N WIND G 35-40KT POSSIBLE. .WEDNESDAY...VFR. N WIND G20-25KT POSSIBLE. .WEDNESDAY NIGHT...VFR. .THURSDAY...VFR. E WIND G 20-25KT POSSIBLE. THURSDAY NIGHT-FRIDAY NIGHT...VFR. .SATURDAY...LOW CHANCE OF -SHRA...WITH MVFR OR LOWER POSSIBLE IF -SHRA OCCURS. && .MARINE... THE SCA HAS BEEN EXTENDED THROUGH TUE ON THE HARBOR BAYS AND SOUND. THE SCA MAY NEED TO BE UPGRADED TO A GALE WARNING FOR TUE AFTERNOON. POTENTIAL FOR FOG ON THE WATERS INCREASES TONIGHT AND CONTINUES INTO TUESDAY. A DENSE FOG ADVISORY HAS BEEN ISSUED WITH EXPECTATION OF VSBY TO DROP BELOW 1 NM OVERNIGHT WITH CONTINUED MOIST FLOW. SCA GUST ON THE NEARSHORE WATERS ARE EXPECTED TO FALL BELOW SCA LATE THIS EVENING AS MIXING DECREASES...BUT SCA CONDITIONS ON THE OCEAN ARE EXPECTED TO CONTINUE THROUGH TONIGHT WITH MARGINAL GUSTS AND SEAS. GALES POSSIBLE TUESDAY FOR OCEAN WATERS AND PERHAPS ALL WATERS AS STRONG COLD FRONT APPROACHES...BUT BETTER CHANCE WILL BE IN WAKE OF THE COLD FRONT TUESDAY NIGHT WITH STRONG COLD AIR ADVECTION. HAVE HELD OFF ON GALE WARNING WITH MARGINAL NATURE OF GALES ON TUESDAY. WAVES WILL REMAIN AT OR ABOVE 5 FT THROUGH FRIDAY NIGHT. WIND GUSTS ABOVE 25 KT ON WEDNESDAY...BUT DIMINISHING THROUGHOUT THE DAY AS THE STORM SYSTEM MOVES AWAY FROM THE AREA...COMING BELOW 25 KT BY THE AFTERNOON. WINDS INCREASE TO ABOVE 25 KT AGAIN ON THURSDAY...BUT DIMINISH THURSDAY NIGHT...AND FOR THE MOST PART...SHOULD REMAIN BELOW 25 KT THROUGH THE BEGINNING OF THE WEEKEND. && .HYDROLOGY... QPF OF 1 TO 2 INCHES...NEARLY ALL RAIN...EXPECTED FROM LATE TONIGHT INTO TUE NIGHT...WITH POTENTIAL FOR HIGHER END LOCAL AMOUNTS OF 2 TO 3 INCHES. MODERATE POTENTIAL EXISTS FOR MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS AND FLASHY SMALL STREAMS. THERE IS A LOW PROBABILITY OF FLASH FLOODING ACROSS NE NJ WITH ANY TRAINING OF HEAVY RAIN/EMBEDDED CONVECTION AS 1 HR FFG IS ONLY AROUND 3/4 OF AN INCH. NOTE...MINOR FLOODING CONTINUE ALONG THE CONNECTICUT RIVER. ADDITIONAL HEAVY RAINFALL WILL LIKELY CAUSE WATER LEVELS TO CONTINUE TO RISE THROUGH THE WEEK...WITH POTENTIAL FOR MODERATE FLOOD LEVEL TO BE REACHED. MONITOR THE LATEST FLOOD WARNINGS FROM NWS TAUNTON MA. THEREAFTER...NO SIGNIFICANT PRECIPITATION THROUGH THE WEEKEND. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...DENSE FOG ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ330-335- 338-340-345. GALE WATCH FROM THIS EVENING THROUGH LATE TONIGHT FOR ANZ330- 335-338-340-345. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ330- 335-338-340-345. DENSE FOG ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ350-353- 355. GALE WATCH FROM 10 AM EDT THIS MORNING THROUGH LATE TONIGHT FOR ANZ350-353-355. SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR ANZ350- 353-355.
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