Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 050635 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 235 AM EDT TUE MAY 5 2015 .SYNOPSIS... HIGH PRESSURE REMAINS OVER THE ATLANTIC AS A COLD FRONT APPROACHES FROM THE NORTHWEST TONIGHT. THE COLD FRONT MOVES ACROSS THE AREA TUESDAY AND TUESDAY NIGHT. HIGH PRESSURE BUILDS OVER THE REGION FOR THE MIDDLE TO THE END OF THE WEEK. A FRONTAL BOUNDARY PASSES NORTH OF THE AREA THIS WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SOME MINOR ADJUSTMENTS WITH RESPECT TO TEMPERATURES...DEWPOINTS AND CLOUD COVERAGE TO BETTER MATCH OBSERVED TRENDS. OVERALL...THE FORECAST REMAINS ON TRACK. MODELS REMAIN IN GOOD AGREEMENT WITH SFC HIGH PRESSURE DRIFTING EAST TONIGHT OVER THE WESTERN ATLANTIC AS A COLD FRONT APPROACHES FROM THE NW. THE FRONT SHOULD MOVE INTO THE NW PORTION OF THE CWA BETWEEN 6 AND 10Z OVERNIGHT. ALOFT...ZONAL FLOW PREVAILS ACROSS THE NORTHEAST FOR THE REMAINDER OF THE NIGHT. CLOSED LOW WELL UP IN EASTERN CANADA MOVES EAST. A GENERAL SW FLOW WILL DECREASE THROUGHOUT TONIGHT. MOSTLY CLEAR CONDITIONS WILL YIELD TO MORE CLOUDS AHEAD OF THE FRONT LATE TONIGHT. MESOSCALE MODELS INCLUDING ARW AND WRF-NMM SHOW SHOWERS ALONG AND AHEAD OF THE FRONT DISSIPATING AS THEY NEAR THE AREA LATE TONIGHT. NCEP MODELS INCLUDING SREF MEAN INDICATE LIGHT QPF VIA WEAKENING SHOWER ACTIVITY BEFORE 10Z TONIGHT...SO WILL MAINTAIN MINIMAL POPS FOR NW ZONES AS THEY NEAR THE AREA. ABOVE NORMAL TEMPS EXPECTED OVERNIGHT...WITH LOWS RANGING FROM AROUND 50 ACROSS THE INTERIOR TO THE LOWER 60S IN AND AROUND NYC. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... ZONAL FLOW INITIALLY WILL GIVE WAY TO A LATE DAY AND OVERNIGHT 500- 700 HPA TROUGH. THIS FEATURE IS MORE PRONOUNCED IN THE 12Z NAM. ANY MORNING ISOLATED SHOWER ACTIVITY WILL GIVE WAY TO SLIGHTLY HIGHER COVERAGE LATER IN THE MORNING...DURING THE AFTERNOON AND INTO THE EVENING HOURS. NAM...WRF-NMM SHOW CONVECTION UPSTREAM IN PA RIDING ALONG THE RIDGE EARLY IN THE DAY APPROACHING OUR REGION LATE. IT APPEARS THAT THE BETTER COVERAGE WILL BE JUST SOUTH OF THE FRONT FROM NE NJ/NYC SOUTHWARD. ECMWF/GFS AND SREF MEAN SUPPORT LESS COVERAGE WITH LOWER POPS. AT THIS TIME...WILL NOT STRAY TOO FAR FROM PREVIOUS FORECAST...RAISING POPS SLIGHTLY BUT CAPPING THEM IN THE CHANCE RANGE. HIGHEST POPS SW ZONES...AND LOWEST NE. THIS SUPPORTED BY LATEST DAY 2 SPC OUTLOOK FOR THUNDERSTORMS AS MARGINAL INSTABILITY IS PRESENT TO THE SOUTH AND WEST...IF NOT A LOT OF UPPER SUPPORT. DEPENDING ON THE LOCATION OF THE FRONT...ANY LINGERING SHOWER OR TSTM ACTIVITY WILL REMAIN OR PASS SOUTH TUESDAY NIGHT...WITH POPS LOWERING THROUGH THE NIGHT. EXPECT HIGH PRESSURE TO THE NORTH TO PUSH THE FRONT JUST TO OUR SOUTH DURING THE EVENING HOURS. ANOTHER UNSEASONABLY WARM DAY IS ON TAP DESPITE THE CLOUDS. READINGS MAY BE SLIGHTLY LOWER...BUT STILL EXPECT 80 DEGREES AWAY FROM THE WATER...WITH NEAR 70 OVER EASTERN SECTIONS OF THE CWA. WITH THE FRONT IN OUR PROXIMITY...WINDS WILL NOT BE AS STRONG...SO LESS DISPARITY IN TEMPS FROM WHAT OCCURRED EARLIER TODAY. TUESDAY LOWS WILL RUN ABOVE NORMAL...BUT WILL BE A FEW DEGREES COOLER THAN TONIGHT`S EXPECTED TEMPERATURES. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... COLD FRONT CONTINUES TO MOVE SOUTH AND EAST OF THE AREA WEDNESDAY MORNING. JUST A SLIGHT CHANCE FOR SOME LINGERING SHOWERS OVER SOUTHEAST ZONES IN THE MORNING...AND THEN CONDS CLEAR OUT FOR THE AFTERNOON. HIGH PRES BOTH AT THE SURFACE AND ALOFT WILL BUILD EAST AND OVER THE AREA FOR THE MIDDLE TO THE END OF THE WEEK...AND THEN THE HIGH MOVES OFFSHORE ON FRIDAY. DRY CONDS WITH NEAR TO ABOVE NORMAL TEMPS THROUGH THE END OF THE WORK WEEK WITH HIGHS GENERALLY IN THE 70S...WARMING INTO THE LOWER 80S ACROSS THE INTERIOR BY FRIDAY. WITH A LIGHT PRES GRADIENT...CAN EXPECT AFTERNOON SEA BREEZES...RESULTING IN COOLER AFTERNOON TEMPS FOR COASTAL AREAS. LOW PRES SLOWLY TRACKS THROUGH THE GREAT LAKES AND INTO THE OHIO VALLEY FOR THIS WEEKEND...AND A FRONTAL BOUNDARY WILL EXTEND FROM THIS SYSTEM AND MOVE WELL NORTH OF THE REGION. SATURDAY SHOULD BE DRY...BUT THE FRONT WILL BEGIN TO SAGE TO THE SOUTH FOR SUNDAY AND MONDAY...AND SCATTERED SHOWERS AND AFTERNOON THUNDERSTORMS ARE POSSIBLE FOR THE START OF THE NEW WEEK. WILL CAP POPS AT LOW CHANCE FOR NOW...WITH HIGHEST POPS ACROSS THE INTERIOR...WHICH WILL BE CLOSER TO THE FRONT. NEAR TO ABOVE NORMAL TEMPS WILL LIKELY CONTINUE FOR THE WEEKEND AND START OF THE NEW WEEK. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... A WEAK FRONTAL BOUNDARY APPROACHING FROM THE NORTHWEST WILL SLOWLY DROP THROUGH THE AREA THIS MORNING REMAINING IN THE VICINITY THROUGH THE EVENING. VFR THROUGH 06Z WED. WITH THE FRONTAL BOUNDARY IN THE VICINITY THE WIND FORECAST AT ALL THE TERMINALS WILL BE TOUGH AND HAVE LOW TO MODERATE CONFIDENCE...ESPECIALLY AFT 12Z. FLOW LIGHTENS THIS AFTN WITH SEABREEZES EXPECTED AT MOST OF THE COASTAL TERMINALS. LOWER CONFIDENCE THAT IT WILL MAKE IT TO KEWR/KTEB SO HAVE LEFT OUT FOR NOW. THERE IS LITTLE FORCING WITH THE FRONT AND MUCH OF THE GUIDANCE IS SHOWING VERY ISOLD TO NO SHOWERS THROUGH 06Z WED. THEREFORE HAVE REMOVED ANY MENTION OF PCPN AND THUNDER. VAD WIND PROFILES INDICATING WINDS OF 50-60 KT BETWEEN 1-2KFT...5-10 KT HIGHER THAN ANY GUIDANCE IS SHOWING. HAVE ADDED LLWS TO NYC TERMINALS...KISP/KBDR/KGON THROUGH 08-10Z...W TO E. .OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY... .TONIGHT THROUGH SATURDAY...VFR. && .MARINE... WINDS GUST 20-25 KT ON THE OCEAN WITH LOWER WINDS FOR OTHER WATERS. AS LOW LEVEL JET INCREASES AHEAD OF COLD FRONT...WILL NOT HAVE TO MIX MUCH TO BRING DOWN HIGHER WINDS. INVERSION HOLDING COULD LIMIT GUSTS TO MAINLY NEAR 20 KT. SEAS PER WAVE WATCH III BUILD TO 5 FT TONIGHT WHERE SCA REMAINS IN EFFECT. ELSEWHERE...SOUTH TO SOUTHWEST FLOW WILL LIGHTEN AS THE NIGHT PROGRESSES. A COLD FRONT APPROACHES AND TRACKS JUST NORTH OF THE WATERS TUESDAY...AND SETTLES OVERHEAD TUESDAY NIGHT. WINDS LIGHTEN AND WILL EVENTUALLY SHIFT AROUND TO THE N/NE LATE TUESDAY NIGHT...DEPENDING ON THE EXACT LOCATION OF THE FRONT. WITH HIGH PRES AND A LIGHT PRES GRADIENT OVER THE WATERS FOR THE MIDDLE TO THE END OF THE WEEK...CAN EXPECT TRANQUIL CONDS DURING THE LONG TERM PERIOD. SOME AFTERNOON GUSTS TO 20 KT POSSIBLE ACROSS THE NEAR SHORE WATERS DUE TO SEA BREEZES. && .HYDROLOGY... GENERALLY EXPECT FROM 1/10 TO 1/4 INCH OF BASIN AVERAGE RAINFALL TUESDAY AND TUESDAY NIGHT FROM SCATTERED SHRA/ISOLD TSTMS. HOWEVER CANNOT COMPLETELY RULE OUT LOCALLY HEAVY RAINFALL IN ANY STRONGER CONVECTION. IF THIS DOES OCCUR OVER AN AREA...THEN LOCALIZED MINOR FLOODING OF URBAN AND POOR DRAINAGE AREAS WOULD BE POSSIBLE. THIS IS A LOW PROBABILITY THOUGH. DRY CONDITIONS ARE EXPECTED WEDNESDAY THROUGH THE WEEKEND. NEXT CHANCE FOR SHRA/TSRA WILL BE ON SUNDAY AND MONDAY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ350-353-355. && $$

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