Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KOKX 202328 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 728 PM EDT WED MAY 20 2015 .SYNOPSIS... HIGH PRESSURE BUILDS IN FROM THE WEST TONIGHT. AN AREA OF LOW PRESSURE DEVELOPS OVER THE MID ATLANTIC STATES ON THURSDAY...THEN TRACKS TO THE SOUTHEAST OF LONG ISLAND THURSDAY NIGHT. A COLD FRONT APPROACHES FROM THE WEST FRIDAY MORNING...THEN CROSSES THE TRI-STATE LATE FRIDAY. HIGH PRESSURE WILL THEN BUILD IN THROUGH EARLY SUNDAY. A WARM FRONT WILL THEN SLOWLY APPROACH FROM THE SOUTHWEST LATE SUNDAY THROUGH TUESDAY. THE FRONT MAY LIFT TO THE NORTH WEDNESDAY MORNING...AND BE FOLLOWED BY A COLD FRONT LATER WEDNESDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
NOT MUCH CHANGE WITH THIS UPDATE. MINOR ADJUSTMENTS TO SKY...TEMP...AND DEWPOINT GRIDS TO ACCOUNT FOR THE LATEST OBS/TRENDS. ZONAL FLOW ALOFT OVERNIGHT...WILL BRING IN MAINLY HIGH CLOUDS FROM THE OHIO VALLEY TO REPLACE CURRENT STRATO-CUMULUS OVER MOST OF THE REGION. THEN WILL HAVE SOME MID CLOUDS MOVE IN FROM THE SW LATE AHEAD OF DEVELOPING LOW PRESSURE OVER THE CENTRAL APPALACHIANS. QUESTION IS HOW MUCH IMPACT WILL THE CIRRUS THEN MID CLOUDS HAVE ON LOW TEMPERATURES. BECAUSE OF THE CIRRUS DID NOT UNDER CUT A BLEND OF MAV/MET/ECS GUIDANCE IN NORMALLY COOLER AREAS. ALSO DID NOT INTRODUCE FROST DUE TO UNCERTAINTY IN EXTENT/AMOUNT OF RADIATIONAL COOLING AS WELL. LOWS TONIGHT SHOULD BE AROUND 5 DEGREES BELOW NORMAL.
-- End Changed Discussion --
&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... LOW PRESSURE DEVELOPS OVER THE MID ATLANTIC THURSDAY IN RESPONSE TO A NORTHERN STREAM 700-500 HPA SHORTWAVE MOVING ACROSS THE OHIO AND TENNESSEE RIVER VALLEYS. WILL SEE CONTINUED INCREASE IN CLOUD COVER THROUGH THE DAY AS THE NORTHERN STREAM SHORTWAVE APPROACHES. ALSO APPEARS COULD SEE SOME LIGHT RAIN ALONG COASTAL PORTIONS OF NYC/LONG ISLAND IN THE AFTERNOON...SO SLIGHT CHANCE TO LOW END CHANCE POPS THERE...AND DRY ELSEWHERE. COVERAGE OF RAIN SHOULD INCREASE THURSDAY NIGHT AS NORTHERN STREAM SHORTWAVE DIGS AND STRENGTHENS AS IT CROSSES THE AREA...WITH BEST COVERAGE/HEAVIEST RAINFALL LIKELY 3-9Z - WITH BEST CHANCE OVER SE ZONES - WHERE THERE ARE LIKELY POPS. FOR HIGHS THURSDAY USED A BLEND OF MIXING DOWN FROM 900-875 HPA PER BUFKIT SOUNDINGS...WITH NAM 2-METER TEMPERATURES AND A BLEND OF MAV/ECS/MET GUIDANCE. HIGHS SHOULD BE AROUND 5-10 DEGREES BELOW NORMAL. FOR LOWS TUESDAY NIGHT A BLEND OF NAM 2-METER TEMPERATURES WITH MAV/MET/ECS GUIDANCE WAS USED...WITH VALUES FORECAST TO BE NEAR TO SLIGHTLY BELOW NORMAL. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AN UPPER LOW WILL DIG SE ACROSS QUEBEC AND NORTHERN NEW ENGLAND FRI INTO SAT. DEGREE OF PHASING WITH THIS LOW AND THE SHORTWAVE RESPONSIBLE FOR LOW PRESSURE PASSING TO THE SOUTH WILL DETERMINE CHANCES FOR RAIN FRI MORNING...AT THIS TIME FORECAST ONLY SLIGHT CHANCE POP FOR ERN LONG ISLAND AND SE CT...THEN SLIGHT CHANCE POP THROUGHOUT IN THE AFTERNOON AS A COLD FRONT MOVES ACROSS. SFC HIGH PRESSURE IN ITS WAKE WILL BUILD FROM THE GREAT LAKES FRI NIGHT...TO THE MID ATLANTIC REGION ON SAT...TO JUST OFFSHORE ON SUNDAY...WITH FAIR WEATHER FOR THE WEEKEND. GLOBAL MODELS STILL DIFFER ON THE TIMING OF A WARM FRONTAL APPROACH/PASSAGE EARLY NEXT WEEK...WITH THE GFS DEPICTING A WEAKER NORTHERN STREAM ACROSS QUEBEC THAN THE ECMWF THAT WOULD ALLOW THE FRONT TO APPROACH SUNDAY NIGHT...ALMOST A DAY QUICKER THEN THE ECMWF. LEANING MORE TOWARD THE SLOWER SCENARIO...WITH ONLY SLIGHT CHANCE POP SUNDAY NIGHT AND MEMORIAL DAY...THEN CHANCE POP MON NIGHT INTO TUE NIGHT. INSTABILITY SLOWLY INCREASES THROUGH THIS PD...EVENTUALLY BECOMING SFC-BASED...SO MENTIONED CHANCE THUNDER ON TUE FROM NYC NORTH/WEST. GFS/ECMWF AGREE THAT THE WARM FRONT SHOULD LIFT TO THE NE BY WED MORNING...BUT COULD BE FOLLOWED BY A WEAK COLD FRONT OR PRE-FRONTAL TROUGH WED AFTERNOON...WITH CHANCE OF AFTERNOON SHOWERS/TSTMS ONCE AGAIN MAINLY FROM NYC NORTH/WEST. TEMPS ON FRI LOOK TO BE NEAR AVG. THEN AFTER SOME COOLER THAN AVG CONDITIONS ON SAT FOLLOWING THE COLD FRONTAL PASSAGE...TEMPS WILL GRADUALLY MODIFY TO ABOVE AVG LEVELS EARLY NEXT WEEK...ALONG WITH INCREASING HUMIDITY. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
HIGH PRESSURE BUILDS IN FROM THE WEST THROUGH TONIGHT. LOW PRESSURE WILL PASS SOUTH OF THE REGION ON THURSDAY. VFR THROUGH THE TAF PERIOD. WIND GUSTS WILL DIMINISH THIS EVENING AND OVERNIGHT WITH OUTLYING TERMINALS WILL LIKELY LIGHT AND VARIABLE. FLOW BECOMES SW ON THURSDAY AROUND 6-10 KT. SOME -RA WILL DEVELOP FOR CITY AND LONG ISLAND TERMINALS THURSDAY AFTERNOON....BUT CATEGORIES WILL REMAIN VFR. 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 COULD END A FEW HOURS EARLIER THAN INDICATED IN TAF. KLGA FCSTER COMMENTS: GUSTS COULD END A FEW HOURS EARLIER THAN INDICATED IN TAF. KEWR FCSTER COMMENTS: GUSTS COULD END A FEW HOURS EARLIER THAN INDICATED IN TAF. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: GUSTS COULD END A FEW HOURS EARLIER THAN INDICATED IN TAF. .OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY... .THU AFTERNOON-THU NIGHT...POSSIBLE MVFR IN RAIN. OTHERWISE VFR. .FRI-FRI NIGHT...POSSIBLE MVFR EARLY. OTHERWISE VFR. NW GUSTS 15-20 KT...POSSIBLY UP TO 25 KT. .SAT-SUN...VFR. S-SW WIND GUSTS BETWEEN 15-20 KT LATE SUN MORNING AND SUN AFTERNOON. .MON...CHANCE OF SUB-VFR IN RAIN.
-- End Changed Discussion --
&& .MARINE... AFTER GUSTS TO AROUND 20 KT...WITH OCCASIONAL GUSTS TO 25 KT NEAR SHORE EARLY THIS EVENING...WINDS DECREASE TO 10 KT OR LESS ON ALL WATERS BY THURSDAY MORNING...AND REMAIN SO THROUGH THURSDAY NIGHT. AS A RESULT...NO MARINE HEADLINES ARE ANTICIPATED TONIGHT-THURSDAY NIGHT. NEAR SHORE SCA CONDITIONS ARE LIKELY FRI AFTERNOON AND EARLY EVENING AHEAD OF AND JUST FOLLOWING A COLD FRONTAL PASSAGE...ESPECIALLY IN THE WATERS SURROUNDING NYC AND WESTERN LONG ISLAND SOUND...WHERE WNW WINDS MAY GUST TO 25 KT. SW FLOW INCREASING TO 15-20 KT ON THE NORTHERN PERIPHERY OF HIGH PRESSURE OFF THE MID ATLANTIC COAST MAY BUILD OCEAN SEAS TO 5 FT SUNDAY AFTERNOON/EVENING...ESPECIALLY FARTHER EAST WHERE A LONGER FETCH WILL EXIST. && .FIRE WEATHER... THURSDAY WILL BE THE DAY WHEN THE AREA WILL BE CONSIDERED AS BEING IN VEGETATION STAGE 3 /GREENUP/. HOWEVER...WEATHER CONDITIONS ON FRIDAY MAY STILL BE CONDUCIVE TO GROWTH/SPREAD OF ANY FIRES THAT DEVELOP...SINCE NOT MUCH RAIN IS EXPECTED THU-THU NIGHT AS LOW PRESSURE PASSES TO THE SOUTH...FOLLOWED BY WITH MIN RH IN THE 20S AND W-NW WINDS GUSTING TO 25-30 MPH FRI AFTERNOON. KBDI IS IN THE 100S ACROSS MOST OF SRN CT AND THE LOWER HUDSON VALLEY AND IN THE 200S ACROSS NYC METRO AND LONG ISLAND..BUT MAY NOT BE FULLY REPRESENTATIVE OF THE PERSISTENT DRY CONDITIONS THAT HAVE BEEN IN PLACE. && .HYDROLOGY... DRY THROUGH THURSDAY MORNING...THEN THERE IS THE POTENTIAL FOR A TENTH OF AN INCH OR LESS OF RAIN FROM THURSDAY AFTERNOON INTO FRIDAY MORNING. THERE IS STILL SOME UNCERTAINTY AS TO EXACTLY HOW MUCH RAIN WILL FALL...WITH SOME POTENTIAL FOR MAINLY THE SE PORTION OF THE CWA TO RECEIVE 1/4 INCH OR MORE OF RAINFALL. THERE IS A CHANCE OF SIGNIFICANT RAINFALL LATE SUNDAY NIGHT INTO EARLY NEXT WEEK. MODEL UNCERTAINTIES ON TIMING/PLACEMENT OF ANY HEAVY RAIN ARE STILL TOO LARGE TO MERIT MENTION OF SPECIFIC AMOUNTS...AND MAY NOT EVEN PAN PER MODEL FORECASTS OUT GIVEN THE PERSISTENT DRY PATTERN THAT HAS BEEN IN PLACE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/MALOIT NEAR TERM...JC/MALOIT SHORT TERM...MALOIT LONG TERM...GOODMAN AVIATION...DS MARINE...GOODMAN/MALOIT FIRE WEATHER... HYDROLOGY...GOODMAN/MALOIT

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.