Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 311454 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1054 AM EDT TUE MAR 31 2015 .SYNOPSIS... LOW PRESSURE TRACKS INTO THE MID ATLANTIC STATES TODAY...THEN PASSES SOUTH OF LONG ISLAND TONIGHT. HIGH PRESSURE BUILDS TO THE SOUTH FROM WEDNESDAY INTO THURSDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST THURSDAY NIGHT...THEN MOVE SLOWLY ACROSS FRIDAY AND FRIDAY NIGHT. ANOTHER COLD FRONT WILL APPROACH ON SATURDAY...THEN PUSH TO THE SOUTH INTO SUNDAY. THE FRONT SHOULD THEN STALL NEAR THE AREA INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... LOW PRESSURE OVER THE OHIO VALLEY MOVES TOWARDS THE REGION TODAY...PASSING SOUTH OF NYC THIS EVENING. PRECIPITATION IS FORECAST TO MOVE INTO THE AREA EARLY THIS AFTERNOON...AND SPREAD EASTWARD THROUGH AFTERNOON. WITH TEMPERATURES AT OR ABOVE 40 DEGREES...PRECIPITATION SHOULD START AS RAIN ACROSS MUCH OF THE REGION. ACROSS SOME OF THE HIGHER ELEVATIONS...ESPECIALLY IN NJ...THE PRECIPITATION COULD START AS A RAIN/SNOW MIX. TEMPERATURES ARE EXPECTED TO REMAIN STEADY OR SLIGHTLY COOL AS THE AFTERNOON PROGRESSES. A WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR THE HIGHER ELEVATIONS OF WESTERN PASSAIC COUNTY...WHERE THE BEST CHANCE OF ACCUMULATING SNOW EXISTS. 2-3 INCHES OF SNOW REMAIN POSSIBLE...HOWEVER WITH TEMPERATURES WARMER THAN FORECAST...THIS WILL NEED TO BE MONITORED. WOULD STILL EXPECT A SLICK EVENING COMMUTE THERE AS TEMPERATURES FALL THIS EVENING WITH THE SNOWFALL. THERE IS A LOW CHANCE THE ADVISORY COULD BE EXPANDED NORTHWARD INTO THE LOWER HUDSON VALLEY. THIS TOO WILL NEED TO BE MONITORED. AS TEMPERATURES COOL THROUGH THE EVENING/OVERNIGHT...LOCATIONS CLOSER TO THE COAST COULD SEE THE RAIN CHANGING OVER TO SNOW...HOWEVER LITTLE SNOW ACCUMULATION IS EXPECTED. IT IS POSSIBLE A QUICK INCH WILL BE POSSIBLE AFTER DARK. PRECIPITATION SHOULD TAPER OFF AFTER MIDNIGHT AS THE ASSOCIATED H8 LOW AND MID LEVEL TROUGH PASS TO THE EAST...WITH CLEARING SKIES FROM WEST-EAST. LOWS SHOULD RANGE FROM THE LOWER 30S IN THE VICINITY OF NYC...TO 25-30 MOST ELSEWHERE...TO SOME LOWER 20S IN THE VALLEYS WELL NORTH/WEST OF THE CITY. && .SHORT TERM /WEDNESDAY/... EXPECT DRY WEATHER ON WED...WITH PERHAPS SOME BKN CLOUDS DURING LATE MORNING AND EARLY AFTERNOON FROM NYC WEST A WEAKENING UPPER TROUGH MOVES ACROSS. HIGHS SHOULD BE MOSTLY IN THE MID 40S... WHICH IS 5-8 DEG BELOW AVG. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... DEEP LAYERED RIDGING BUILDS OVER THE AREA WEDNESDAY NIGHT AND THURSDAY...WITH ASSOCIATED SUBSIDENCE KEEPING THINGS DRY. FOR LOWS WEDNESDAY NIGHT USED A BLEND OF MAV/MET/ECS GUIDANCE WITH VALUES EXPECTED TO BE A FEW DEGREES BELOW NORMAL. FOR HIGHS ON THURSDAY A BLEND OF MIXING DOWN FROM 975-925 HPA PER BUFKIT SOUNDINGS...WITH NAM 2-METER TEMPERATURES AND A BLEND OF MAV AND MET GUIDANCE WAS USED. HIGHS SHOULD BE A FEW DEGREES BELOW NORMAL. THE DEEP LAYERED RIDGE AXIS SLIDES TO THE EAST THURSDAY EVENING...ALLOWING FOR LOW-MID LEVEL MOISTURE TO RAPIDLY INCREASE IN ITS WAKE. PASSAGE OF A SURFACE WARM FRONT TO THE N AND WEAK 700 AND 500 HPA SHORTWAVES SHOULD PRODUCE SUFFICIENT FORCING TO WARRANT CHANCE POPS THROUGHOUT...MAINLY AFTER MIDNIGHT. ALSO...NAM/GFS/ECMWF ALSO SHOW SHOWALTER INDICES IN THE 0 TO 2 RANGE...WARRANTING A SLIGHT CHANCE OF THUNDER TO REFLECT POTENTIAL FOR ELEVATED STORMS. REGION ALSO WILL BE IN THE RIGHT REAR QUADRANT OF 135+KT 300 HPA JET...AND HAVE A WSW 50-60KT LOW LEVEL JET PASS NEAR THE AREA AS WELL. INCREASE POPS TO LIKELY FRIDAY AHEAD OF COLD FRONT...WITH STRONGER SHORTWAVES FORECAST TO PASS THROUGH...A COUPLED UPPER JET STRUCTURE FORECAST TO EVOLVE...AND EXPECTED PERSISTENCE OF LOW LEVEL JET. HAVE ALSO CONTINUED WITH SLIGHT CHANCE OF THUNDER ON FRIDAY AS WELL. SOME DIFFERENCES BETWEEN THE MODELS ON TIMING OF COLD FRONTAL PASSAGE...WITH THE GFS FASTER THAN THE ECMWF AND CMC. HAVE LEANED TOWARDS SLOWER SOLUTION...NOTING GENERAL PROGRESSIVE BIAS TO THE GFS. AS A RESULT CARRY CHANCE POPS INTO SATURDAY MORNING. 500 HPA TROUGH AXIS SLIDES OVER THEN TO THE EAST OF THE AREA SATURDAY AND SATURDAY NIGHT. THE LOW LEVELS THOUGH SHOULD BE SUFFICIENTLY DRY TO PRECLUDE ANY PRECIPITATION. A CLIPPER TYPE LOW WITH A FAIRLY POTENT SHORTWAVE MOVING WITH THE BASE OF A700-500 HPA N STREAM TROUGH PASSES TO THE NE SUNDAY...WITH ITS ASSOCIATED COLD FRONT PUSHING THROUGH...THEN STALLING NEAR OR JUST TO THE S OF THE AREA BY LATE SUNDAY. THE REGION WILL THEN BE UNDER WNW TO ZONAL FLOW ALOFT SUNDAY NIGHT AND MONDAY. FOR NOW WENT WITH A DRY FORECAST SUNDAY NIGHT/MONDAY...BUT THERE IS THE POSSIBILITY THAT SHORTWAVES EMBEDDED IN THE FLOW ALOFT COULD ACT ON THE FRONTAL BOUNDARY STALLED NEAR BY. HOWEVER...AT THIS TIME DO NOT QUITE HAVE CONFIDENCE IN THIS OCCURRING TO PLACE IN THE FORECAST. FOR TEMPERATURES THURSDAY NIGHT-MONDAY USED A BLEND OF MEX/ECE/ECM/WPC GUIDANCE WITH NAM 2-METER TEMPERATURES BLENDED IN THURSDAY NIGHT AS WELL. TEMPERATURES SHOULD BE ABOVE NORMAL THURSDAY NIGHT-FRIDAY NIGHT...THEN BELOW NORMAL SATURDAY-MONDAY. HOWEVER...DEPARTURES SHOULD NOT BE VERY LARGE...GENERALLY LESS THAN 10 DEGREES. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... LOW PRES OVER THE OHIO VALLEY TRACKS ACROSS THE TERMINALS TODAY AND DEPARTS TONIGHT. NO SIGNIFICANT CHANGES MADE TO PREVIOUS TAF PACKAGE. VFR UNTIL PRECIP SPREADS OVER THE TERMINALS FROM WEST TO EAST. PRECIP WILL MAINLY BE RAIN FOR SOUTHERN TERMINALS...POSSIBLY MIXING WITH SNOW EARLY THIS EVENING BEFORE TAPERING OFF. FOR THE INTERIOR...MAINLY KSWF...PRECIP SHOULD BE ALL SNOW. FOR ALL OTHER TERMINALS...PRECIP STARTS OUT AS RAIN...AND THEN MIXES WITH AND CHANGES TO SNOW THIS EVENING. NOT EXPECTING MUCH IN THE WAY OF RUNWAY ACCUMULATIONS FOR KNYC TERMINALS...AND LESS THAN AN INCH ELSEWHERE. KSWF COULD PICK UP A LITTLE OVER AN INCH. CONDS IMPROVE TO VFR TONIGHT AS LOW PRES DEPARTS AND HIGH PRES BUILDS IN BEHIND IT. SW WINDS 5-10 KT THROUGH AFTERNOON WILL BECOME LGT/VRB AS THE LOW MOVES OVERHEAD...AND THEN WINDS BECOME NW 10-15 KT TONIGHT THROUGH WEDNESDAY. ...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: MVFR CONDS DEVELOPING THIS AFTERNOON IN - RA...THEN DROPPING TO IFR FROM TIME TO TIME THIS EVENING IN -RA/-SN. WINDS WILL BE TO THE LEFT OF 310 MAG UNTIL THIS EVENING. KLGA FCSTER COMMENTS: MVFR CONDS DEVELOPING THIS AFTERNOON IN - RA...THEN DROPPING TO IFR FROM TIME TO TIME THIS EVENING IN -RA/-SN. WINDS WILL BE TO THE LEFT OF 310 MAG UNTIL THIS EVENING. KEWR FCSTER COMMENTS: MVFR CONDS DEVELOPING THIS AFTERNOON IN - RA...THEN DROPPING TO IFR FROM TIME TO TIME THIS EVENING IN -RA/-SN. WINDS WILL BE TO THE LEFT OF 310 MAG UNTIL THIS EVENING. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: MVFR CONDS DEVELOPING THIS AFTERNOON IN - RA...THEN DROPPING TO IFR FROM TIME TO TIME THIS EVENING IN -RA/-SN. WINDS WILL BE TO THE LEFT OF 310 MAG UNTIL THIS EVENING. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. .OUTLOOK FOR 15Z WEDNESDAY THROUGH SATURDAY... .WEDNESDAY-THURSDAY...VFR. .THURSDAY NIGHT-FRIDAY NIGHT...MVFR IN RAIN SHOWERS. .SATURDAY...SUB VFR POSSIBLE IN SHOWERS EARLY...THEN VFR LATE. && .MARINE... SMALL CRAFT CONDITIONS ON THE OCEAN WATERS THROUGH WEDNESDAY. SEAS WILL START OFF BELOW SMALL CRAFT CONDITIONS...HOWEVER WIND AND SEAS INCREASE THIS AFTERNOON AND OVERNIGHT AS LOW PRESSURE TRACKS ACROSS THE AREA WATERS. EXPECT WIND GUSTS IN N-NW FLOW UP TO 30 KT AND SEAS BUILDING TO 5-6 FT BEHIND THE LOW TONIGHT. AFTER A LULL FROM WEDNESDAY NIGHT INTO THURSDAY...PERSISTENT SOUTHERLY FLOW COUPLED WITH S SWELL SHOULD BUILD SEAS ON THE COASTAL OCEAN WATERS TO SCA LEVELS LATE THURSDAY AND FRIDAY. SCA LEVEL GUSTS ARE ALSO POSSIBLE ON THE COASTAL OCEAN WATERS FROM LATE THURSDAY INTO FRIDAY AS WELL. AT THIS TIME IT APPEARS THE HARBOR/SOUND/BAYS OF LONG ISLAND SHOULD EXPERIENCE SUB-SMALL CRAFT ADVISORY CONDITIONS TUESDAY NIGHT-FRIDAY. && .HYDROLOGY... QPF OF 2 TO 4 TENTHS OF AN INCH EXPECTED THIS AFTERNOON AND EVENING...WITH SOME OF THIS IN THE FORM OF SNOW ESPECIALLY INLAND. THERE IS ALSO POTENTIAL FOR ABOUT 1/3 TO 1/2 INCH OF RAIN FROM LATE THURSDAY INTO EARLY SATURDAY. RIVERS AND STREAMS ARE EXPECTED TO REMAIN BELOW BANK FULL...BUT INCREASED RIVER/STREAM FLOW ACROSS THE LOWER HUDSON VALLEY AND SOUTHERN CONNECTICUT 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...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR NJZ002. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT WEDNESDAY FOR ANZ350-353- 355. && $$ SYNOPSIS...GOODMAN/MALOIT NEAR TERM...BC SHORT TERM...GOODMAN LONG TERM...MALOIT AVIATION...MPS MARINE...BC/GOODMAN/MALOIT HYDROLOGY...GOODMAN/MALOIT

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