Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 300841 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 441 AM EDT TUE SEP 30 2014 .SYNOPSIS... A BACK DOOR COLD FRONT WILL SLOWLY MOVE THROUGH THIS MORNING. MULTIPLE UPPER LEVEL DISTURBANCES WILL THEN AFFECT THE AREA THROUGH MID WEEK...FOLLOWED BY HIGH PRESSURE BUILDING FROM THE NORTH THURSDAY INTO FRIDAY. A COLD FRONT WILL PASS THROUGH ON SATURDAY...FOLLOWED BY HIGH PRESSURE BUILDING IN ON SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A SHORTWAVE AND VORT MAX MOVING THROUGH THE REGION CONTINUED TO TRIGGER LIGHT RAIN AND SPRINKLES ALONG THE SOUTH SHORE OF LONG ISLAND. MAINTAINED SLIGHT CHANCE POP FOR LONG ISLAND AND MOST OF SOUTHERN CT AS A RESULT. A BACK DOOR COLD FRONT HAD PUSHED THROUGH MOST OF SRN CT AND ERN LONG ISLAND...AND WILL CONTINUE MOVE WEST TO SOUTHWEST THIS MORNING...TURNING LOW LEVEL FLOW IN ITS WAKE TO THE E-NE. AS THE FRONT CONTINUES TO PUSH SLOWLY WSW-WARD AND A WEAK UPPER TROUGH MOVES ACROSS...SHOULD SEE MORE SHOWERS TODAY ESPECIALLY AS THE COMBO OF DAYTIME SFC HEATING AND MID LEVEL COOLING VIA THE UPPER TROUGH INCREASES INSTABILITY. NAM SOUNDINGS SHOW SCAPE OF UP TO 500 J/KG...ENOUGH TO HELP GENERATE SHOWERS BUT NOT THUNDER WITH THE INSTABILITY CONFINED MOSTLY BELOW THE FREEZING LEVEL. FCST LIKELY POP MAINLY FOR LONG ISLAND...WITH CHANCE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... SCT TO NUMEROUS SHOWERS SHOULD CONTINUE TO BE AROUND TONIGHT INTO WED AS AN UPPER LOW APPROACHES FROM THE WEST...THEN MOVES ACROSS ON WED. THE UPPER LOW WILL INTERACT WITH A DEVELOPING INVERTED TROUGH EXTENDING NW-WARD FROM OFFSHORE LOW PRESSURE ON WED... WITH POTENTIAL FOR LOCALLY HEAVIER RAIN OF OVER AN INCH NEAR AND JUST EAST OF WHERE THIS INTERACTION OCCURS...WHICH IS STILL UNCERTAIN DUE TO ITS MESOSCALE NATURE. THE 00Z NAM/GFS AND 29/12Z ECMWF WERE POINTING TOWARD SE CT AND ERN LONG ISLAND...WHILE THE 00Z ECMWF/03Z SREF ARE FARTHER EAST. CLOUDY SKIES AND AND E-NE FLOW OF MARITIME AIR WILL PERSIST... WITH TEMPS A COUPLE OF DEG ABOVE AVG TODAY...THEN NEAR OR SLIGHTLY BELOW AVG ON WED. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... LINGERING CHC FOR PCPN WED EVENING...MAINLY OVER EASTERN AREAS...AS STRONG UPR LVL SHORTWAVE CLOSES OFF AND PUSHES EAST. 00Z MODEL SUITE IN GENERAL AGREEMENT WITH RAIN SHOWERS ENDING OVER AREAS WEST OF NYC BY 06Z...AND THEN EASTERN AREAS BY THURS MORNING. WHILE A BRIEF HEAVY DOWNPOUR IS NOT OUT OF THE QUESTION WED EVENING...THE TREND WITH THE MODELS HAS TO PUSH IT EAST...MOST LIKELY OCCURRING OUTSIDE THE CWA. DRY CONDITIONS THEN SETTING UP THRU THURS NIGHT-FRI WITH SFC HIGH DIPPING SOUTH BETWEEN TWO SFC LOW PRESSURE SYSTEMS...AND RIDGING ALOFT. ATTENTION THEN TURNS TO AN APPROACHING LOW PRESSURE SYSTEM FOR THE FIRST HALF OF THE WEEKEND. SLIGHT DISCREPANCIES WITH 00Z MODELS WITH GFS THE FASTEST SOLUTION AND ECMWF THE SLOWEST. HOWEVER...IT SHOULD BE NOTED ALL MODELS ARE NOW TRENDING FASTER FOR THE PROGRESSION. DEPENDING ON THE STRENGTH OF THE RIDGING...THE MODELS COULD BE WEAKENING IT TOO QUICKLY AND THUS BRINGING THE FRONT AND ASSOCIATED PCPN THROUGH QUICKLY AS WELL. AS SUCH...SLIGHTLY ADJUSTED THE TIMING OF THE PCPN FRI NIGHT-SAT...BUT DID NOT WANT TO DEVIATE TOO MUCH FROM PRIOR FORECAST UNTIL A GOOD HANDLE OF THE TREND CAN BE MADE. CONFIDENCE EXISTS IT WILL RAIN ON SATURDAY...FIGURING OUT THE TIMING WILL NEED TO BE IRONED OUT IN SUBSEQUENT FORECASTS. DRY WX ON FRIDAY...THEN BEGAN POPS AFTER 00Z SAT WITH THE PASSING OF A WEAK SHORTWAVE OUT AHEAD OF THE MAIN UPR LVL LOW. HAVE LIKELY POPS IN BY 12Z SAT MORNING AND THEN TAPER POPS OFF WEST TO EAST SAT NIGHT AS MAIN FORCING ALOFT SWINGS THROUGH THE NORTHEAST. SFC HIGH BUILDS IN THE WAKE OF THE FRONT SUNDAY-MONDAY WHILE THE REGION REMAINS UNDER BROAD TROUGHING. HAVE DRY WX IN FOR SUN-MON WITH THE NEXT CHC OF PCPN COMING BY MON NIGHT. NEAR SEASONAL TEMPS IN PLACE THRU SAT. A BRIEF BURST OF CAA BEHIND THE FRONT WILL SEND TEMPS DOWN A DEGREES BELOW NORMAL FOR SAT NIGHT-SUN NIGHT. HOWEVER...RETURN FLOW QUICKLY SETS UP WITH THE HIGH PRESSURE BUILDING IN...PUSHING TEMPS BACK TO NEAR NORMAL BY MONDAY. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... A COLD FRONT IS SLIDING SOUTH ACROSS THE REGION EARLY THIS MORNING. AS OF 09Z THE FRONT EXTENDED FROM NEAR KISP TO JUST NORTH OF KLGA. THE FRONT SAGS SOUTH OF THE REGION THIS MORNING AS HIGH PRESSURE BUILDS OVER NEW ENGLAND. IFR CIGS ARE LOCATED BEHIND THE FRONT...BUT CONFIDENCE IS LOW ON IF AND WHEN THE STRATUS WILL SPREAD INTO THE NY METRO. EXPECTING IMPROVEMENT BY MID MORNING FROM EAST TO WEST...THOUGH UNSURE OF TIMING DETAILS. FAIRLY CONFIDENT THAT WE`LL BE VFR IN THE AFTERNOON WITH WESTERN SECTIONS THE LAST TO IMPROVE. SOME LIGHT RAIN WITH SCATTERED SHOWERS POSSIBLE EASTERN SECTIONS TODAY. ...NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: UNCERTAINTY IN CIG HEIGHT THIS AM WITH IFR POSSIBLE AROUND 13Z. HIGH CONFIDENCE IN EAST SFC WIND LESS THAN 10 FOR AFTN. KLGA FCSTER COMMENTS: UNCERTAINTY IN CIG HEIGHT THIS AM. IFR POSSIBLE AROUND 13Z. HIGH CONFIDENCE IN SFC WIND FCST. KEWR FCSTER COMMENTS: UNCERTAINTY IN CIG HEIGHT THIS AM. MARGINAL CIG MAY NOT MOVE IN AT ALL. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: UNCERTAINTY IN CIG HEIGHT THIS AM. MARGINAL CIG MAY NOT MOVE IN AT ALL. KHPN FCSTER COMMENTS: CONFIDENT IN THE IMPROVEMENT THIS MORNING...THOUGH UNCERTAINTY IN THE TIMING KISP FCSTER COMMENTS: LOW CONFIDENCE IN THE CEILING FORECAST THIS MORNING. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY... .LATE T0NIGHT...MVFR OR LOWER CIGS POSSIBLE. CHC -SHRA E-NE WINDS AROUND 10 KT. .WED...CHC MVFR CIGS/VSBYS/-SHRA. E-NE WINDS AROUND 10 KT. .THU...CHC MVFR MAINLY AM. NE WINDS AROUND 10 KT. .FRI...VFR. SE-S WINDS AROUND 10 KT. .SAT...RAIN LIKELY - MVFR OR LOWER IN THE AM. SW WINDS AM BECMG WNW PM. GUSTS 20-25KT LIKELY LATE. && .MARINE... INCREASING E-NE FLOW IN THE WAKE OF A BACK DOOR COLD FROPA...AS THE WATERS BECOME SANDWICHED BETWEEN HIGH PRESSURE TO THE NORTH AND DEVELOPING OFFSHORE LOW PRESSURE...SHOULD LEAD TO SCA CONDS TONIGHT INTO WED NIGHT...AND POSSIBLY THU. ISSUED SCA FOR LATE THIS EVENING THROUGH WED AFTERNOON AS FLOW INCREASES TO 20-25 KT AND SEAS BUILD TO 3-5 FT BY LATE EVENING...AND TO 4-7 FT ON WED. GENERALLY EXPECTING SUB-SCA CONDITIONS ON ALL NON-OCEAN WATERS THROUGH THE COMING WEEKEND. FOR THE OCEAN WATERS...OCNL GUSTS UP TO 25 KT WILL BE PSBL WED NIGHT INTO THU...WITH THE WINDS DIMINISHING AS HIGH PRESSURE BUILDS IN THU. COULD SEE ANOTHER CHC FOR 25 KT GUSTS RIGHT AHEAD OF THE FRONT FRI NIGHT-SAT...THEN SUNDAY WITH CAA OVER THE WATERS. SEAS BUILDING IN RESPONSE TO INCREASED WINDS MID WEEK...EXPECTING 4-6 FT SEAS THRU THU BEFORE SUBSIDING WITH THE DIMINISHING WINDS. SEAS WILL BUILD TO 5-7 FT FOR THE WEEKEND BEFORE DROPPING TO LESS THAN 5 FT ONCE AGAIN ON SUNDAY. && .HYDROLOGY... NO SIGNIFICANT PCPN EXPECTED THROUGH TUE NIGHT. A FEW TENTHS OF AN INCH OF RAINFALL...AND LOCALLY UP TO AN INCH...ARE POSSIBLE WED-WED NGT...MAINLY SE CT AND ERN LONG ISLAND. BETWEEN ONE HALF TO ONE INCH OF RAIN IS ALSO POSSIBLE WITH COLD FROPA FRI NIGHT-SAT. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 6 PM EDT WEDNESDAY FOR ANZ350-353-355. && $$ SYNOPSIS...GOODMAN/SEARS NEAR TERM...GOODMAN SHORT TERM...GOODMAN LONG TERM...SEARS AVIATION...TONGUE MARINE...GOODMAN/SEARS HYDROLOGY...GOODMAN/SEARS

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