Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270901 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 501 AM EDT FRI MAR 27 2015 .SYNOPSIS... A COLD FRONT WILL PUSH WELL OFFSHORE THIS MORNING. LOW PRESSURE WILL DEVELOP OFFSHORE TONIGHT...AND TRACK TOWARDS THE MARITIMES SATURDAY. AN UPPER LEVEL DISTURBANCE MOVES ACROSS SATURDAY AND MOVES EAST OF THE REGION SATURDAY NIGHT. HIGH PRESSURE BUILDS IN THEREAFTER. FOR THE NEW WORK WEEK...A SERIES OF CLIPPER LOWS WILL BE MOVING ACROSS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A SLOW MOVING COLD FRONT HAS SLID EAST OF THE REGION EARLY THIS MORNING...BUT LAGGING UPPER TROUGH AND UPPER JET ENERGIES...AND WEAK INVERTED SURFACE TROUGHING...IS EXPECTED TO ALLOW FOR LINGERING POST- FRONTAL RAIN BANDS TO ONLY GRADUALLY SLIDE EAST OF NYC METRO AND POINTS WEST THIS MORNING AND LIKELY NOT UNTIL AFTERNOON FOR E LI/SE CT. NORTHERLY WINDS WILL GRADUALLY ADVECT COLDER AIR INTO THE REGION. CLOUD COVER WILL KEEP TEMPS A FEW DEGREES BELOW SEASONABLE IN THE MID TO UPPER 40S. AROUND 50 NYC/NJ METRO. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... DEEP UPPER TROUGH GRADUALLY PIVOTS TO THE EAST COAST TONIGHT INTO SATURDAY NIGHT...WITH POTENTIAL CLOSED LOW TRACKING OVER THE TRI- STATE TO MID-ATLANTIC VICINITY SATURDAY NIGHT. AT THE SURFACE...LOW PRESSURE TRACKS NE ALONG THE COLD FRONT WELL SE OF THE REGION FRIDAY NIGHT INTO SAT NIGHT. OPERATIONAL MODELS AND RESPECTIVE ENSEMBLE ARE IN FAIRLY GOOD AGREEMENT WITH THE LOW STAYING FAR ENOUGH OFFSHORE TO KEEP THE HEAVIEST PRECIP FROM THIS LOW OFFSHORE. BUT THE MAJORITY OF SOLUTIONS...EXCEPT FOR OPERATIONAL ECWMF...DO SPREAD WESTERN EDGE OF LIGHT PRECIP SHIELD INTO FAR EASTERN LI/SE CT TONIGHT INTO SAT NIGHT. SUNYSB SENSITIVITY ANALYSIS DEPICTS A SLIGHT SPREAD IN ENSEMBLE MEMBERS ON WEST SIDE OF LOW TRACK...DEPICTING A LOW PROB OF SLIGHTLY FARTHER WEST SOLUTION IF THE TROUGH DIGS A BIT DEEPER. THIS WOULD INCREASE PRECIP POTENTIAL FOR MAINLY LI/CT. AT THE SAME TIME...SEVERAL MODELS HAVE BEEN SIGNALING A WEAK INVERTED TROUGH HANGING BACK OVER THE REGION FRI NIGHT INTO SAT AS CLOSED MID-LEVEL LOW APPROACHES. THE TRACK/INTENSITY OF THE MID- LEVEL CLOSED LOW AND ASSOCIATED SURFACE TROUGH LOCATION WILL BE KEY TO POTENTIAL DEVELOPMENT OF ANY STEADIER AND MORE WIDESPREAD PRECIP FRIDAY NIGHT INTO SAT. THE STRENGTH/POSITION OF THIS FEATURE HAS WAVERED FROM MODEL RUN TO MODEL RUN FROM SOUTHERN NEW ENGLAND TO NORTHERN MID ATLANTIC OVER THE LAST SEVERAL DAYS...INSTILLING LOW CONFIDENCE ON WHERE THIS FEATURE SETS UP. WITH THE ABOVE UNCERTAINTY AND POTENTIAL HAVE MAINTAINED AN W TO E GRADIENT OF ONLY CHANCE POPS FRI NIGHT INTO SAT NIGHT. FOR LOCATIONS THAT DO NOT FALL UNDER THE INVERTED TROUGH OR WESTERN EDGE OF PRECIP SHIELD...THERE WILL BE AN ISO/SCT THREAT FOR MAINLY DIURNAL SHOWER ACTIVITY ACROSS THE AREA ON SATURDAY UNDER COMBO OF MID- LEVEL VORT ENERGY AND COLD POOL INSTABILITY. THEREAFTER...MODELS IN GENERAL AGREEMENT WITH THE UPPER TROUGH SLIDING EAST AND SURFACE HIGH BUILDING TOWARDS THE REGION SATURDAY NIGHT WITH GRADUAL TAPERING OF PRECIP ACROSS EASTERN TRI-STATE. IN TERMS OF P-TYPE OF POTENTIAL PRECIP...CAA TONIGHT INTO SAT SHOULD ALLOW PRECIP TO MIX WITH/CHANGE TO WET SNOW LATE TONIGHT. IF PRECIP IS STEADY ENOUGH A MAINLY WET SNOW WOULD BE EXPECTED ON SATURDAY BASED ON THERMAL PROFILE ALOFT...BUT IF IT IS VERY LIGHT AND SCATTERED IN NATURE A RAIN/SNOW MIX WOULD BE LIKELY DUE TO WARMER BOUNDARY LAYER TEMPS. MOST LIKELY SCENARIO AT THIS POINT IS 1-2 INCHES OR LESS OF WET SNOW FRI NIGHT INTO SAT ACROSS EASTERN LI/SE CT...WITH A COATING TO NOTHING FURTHER WEST. IF INVERTED TROUGH DEVELOPS OVER THE REGION...OR OFFSHORE LOW TRACKS A BIT FARTHER WEST...AN ADVISORY LEVEL WET SNOW WOULD BE POSSIBLE...PARTICULARLY LI/CT. TEMPS ON SATURDAY/SAT NIGHT WILL LIKELY RUN ABOUT 10 TO 15 DEGREES BELOW SEASONABLE UNDER THE UPPER TROUGH AND COLD POOL. && .LONG TERM /SUNDAY THROUGH THURSDAY/... HIGH PRESSURE BUILDS INTO THE AREA AT THE SURFACE ON SUNDAY...WITH THE CENTER OF THE HIGH PASSING WELL TO THE SOUTH...WHILE AT THE SAME TIME THERE WILL BE RIDGING ALOFT. THICKNESSES QUICKLY BUILD ON SUNDAY AS THE HIGH PUSHES OFF THE SOUTHEAST COAST LATE IN THE DAY...WHICH MEANS WARMER TEMPERATURES AS COMPARED TO SATURDAY...MAINLY FOR NYC...NORTHEAST NJ...AND LOWER HUDSON VALLEY. LONG ISLAND AND SOUTHERN CT MAY SEE ONLY SLIGHTLY WARMER TEMPERATURES AS WINDS SHIFT TO MORE OF A SOUTHERLY DIRECTION DURING THE DAY. THIS ONSHORE FLOW OFF THE COLD OCEAN WATERS WILL KEEP TEMPERATURES COOLER THAN INLAND AREAS. A COLD FRONT THEN APPROACHES THE AREA SUNDAY NIGHT...AND MOVES THROUGH LATE MONDAY INTO MONDAY NIGHT. SOME LIGHT PRECIPITATION IS POSSIBLE OUT AHEAD OF THE FRONT SUNDAY NIGHT. THERE IS LIMITED MOISTURE TO WORK WITH HOWEVER...SO ONLY SLIGHT CHANCE POPS. WARM AIR ADVECTION AHEAD OF THE FRONT WILL MEAN PRECIPITATION IN THE FORM OF RAIN SHOWERS FOR MUCH OF THE AREA. HOWEVER...THERE MAY BE SOME SNOW SHOWERS WELL INLAND. ANY SNOW WILL CHANGE TO RAIN DURING THE MORNING ON MONDAY. PATTERN BECOMES RATHER PROGRESSIVE AS THE UPPER LEVEL FLOW IS PRETTY ZONAL. AT THE SURFACE...WEAK HIGH PRESSURE BUILDS IN FOR TUESDAY. A QUICK MOVING CLIPPER SYSTEM MOVES THROUGH ON TUESDAY NIGHT...DEPARTING THE AREA ON WEDNESDAY. AGAIN...MUCH OF THE AREA SHOULD BE WARM ENOUGH FOR RAIN...WITH THE POSSIBILITY OF SOME FLAKES MIXING IN TUESDAY NIGHT ACROSS SOUTHERN CT AS COLDER AIR MOVES IN BEHIND THE LOW. A WARM FRONT APPROACHES THE AREA ON WEDNESDAY NIGHT...MOVING THROUGH ON THURSDAY...FOLLOWED QUICKLY BY THE ASSOCIATED COLD FRONT. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... WEAK HIGH PRESSURE BUILDS IN TODAY. RAIN/SHRA CONTINUES INTO THE MORNING PUSH WITH PRIMARILY MVFR CONDS...ALTHOUGH TEMPO VFR CONDS ARE POSSIBLE BEFORE 13-15Z. VFR OTHERWISE PREVAILS THEREAFTER. WINDS N-NNW AROUND 10 KT...DIMINISHING SLIGHTLY THIS AFTERNOON. ...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: GUSTS THRU 13Z MIGHT BE ONLY OCCASIONAL. VFR CIGS COULD TEMPO OR PREVAIL NOW THRU 13Z. KLGA FCSTER COMMENTS: OCCASIONAL GUSTS UP TO AROUND 20 KT UNTIL 13Z. VFR CIGS COULD TEMPO OR PREVAIL NOW THRU 13Z. KEWR FCSTER COMMENTS: GUSTS THRU 13Z MIGHT BE ONLY OCCASIONAL. VFR CIGS COULD TEMPO OR PREVAIL NOW THRU 13Z. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: TEMPO OR PREVAILING VFR CIGS POSSIBLE NOW THRU 13Z. KHPN FCSTER COMMENTS: MVFR/VFR CIGS POSSIBLY TEMPO OR PREVAILING THRU 13Z. KISP FCSTER COMMENTS: TEMPO VFR CIGS POSSIBLE BEFORE 14Z. .OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY... .SAT...CHANCE OF MVFR CONDS WITH ANY RAIN OR SNOW SHOWERS. NW G20- 25KT. .SAT NIGHT. VFR. NW G25KT. .SUN...VFR. .MON...VFR. W G25KT. .TUE...VFR. NW G20KT. && .MARINE... SMALL CRAFT OCEAN SEAS EXPECTED TODAY WITH A GRADUAL SUBSIDE OF HIGH SOUTHERLY SWELLS. MARGINAL SCA CONDS POSSIBLE ON OCEAN TONIGHT WITH GUSTY NW FLOW...CAA...AND RESIDUAL SOUTHERLY SWELLS...WITH BETTER CHANCE OF SCA CONDS SAT NIGHT IN WAKE OF DEPARTING OFFSHORE LOW AND AS HIGH PRESSURE IN FROM THE WEST. WAVES DIMINISH TO SUB SCA ON SUNDAY...BUT BUILD TO ABOVE SCA CRITERIA ON A SOUTHERLY FLOW LATE SUNDAY NIGHT INTO MONDAY AHEAD OF AN APPROACHING WARM FRONT. WINDS MAINLY OVER THE OCEAN WATERS WILL GUST TO 25 KT LATE SUNDAY NIGHT INTO MONDAY NIGHT. WINDS AND WAVES WILL DIMINISH ON TUESDAY AS THE PRESSURE GRADIENT RELAXES WITH WEAK HIGH PRESSURE BUILDING IN. WAVES QUICKLY BUILD AGAIN TO ABOVE SCA CRITERIA TUESDAY NIGHT IN RESPONSE TO SOUTHERLY FLOW AHEAD OF AN APPROACHING CLIPPER SYSTEM...THEN DIMINISH ON WEDNESDAY AS THE SYSTEM DEPARTS THE REGION. && .HYDROLOGY... AN ADDITIONAL 1 TO 2 TENTHS QPF THROUGH THIS AFTERNOON. NO SIGNIFICANT WIDESPREAD PRECIPITATION EXPECTED THROUGH THIS WEEKEND INTO NEXT WEEK. RIVERS AND STREAMS ARE EXPECTED TO REMAIN BELOW BANK FULL...BUT INCREASED RIVER/STREAM FLOW WILL CONTINUE ICE BREAKUP AND MOVEMENT INTO THIS WEEKEND. ISOLATED ICE JAMS ARE POSSIBLE...WHICH IF THEY OCCUR...COULD RESULT IN LOCALIZED FLOODING. SINCE ICE JAM FLOODING IS UNPREDICTABLE AND SUDDEN...INTERESTS ALONG ICE COVERED RIVERS SHOULD MONITOR NWS FORECASTS FOR THE LATEST INFORMATION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEB SITE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...JP/NV NEAR TERM...NV SHORT TERM...NV LONG TERM...JP AVIATION...JC MARINE...JP/NV HYDROLOGY...JP/NV

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