Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 020156 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 956 PM EDT WED APR 1 2015 .SYNOPSIS... HIGH PRESSURE BUILDS OVER THE AREA TONIGHT AND MOVES OFFSHORE ON THURSDAY. A COLD FRONT THEN APPROACHES THURSDAY NIGHT AND FRIDAY...THEN PASS THROUGH LATE FRIDAY NIGHT INTO SATURDAY MORNING. ANOTHER COLD FRONT FOLLOWS ON SUNDAY. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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HIGH PRESSURE AT THE SURFACE AND DEEP LAYERED RIDGING ALOFT ARE BUILDING OVER THE REGION TONIGHT. MANY SUBURBS HAVE ALREADY DECOUPLED WITH TEMPERATURES FALLING RAPIDLY DUE TO EXCELLENT RADIATIONAL COOLING CONDITIONS. WINDS WILL CONTINUE TO DIMINISH OVERNIGHT IN THE CITY AND NEAR THE COAST. CLEAR SKIES FOR THE FIRST PORTION OF THE NIGHT...WITH POTENTIAL FOR SOME CLOUD COVER AFTER 06Z FROM WARM ADVECTION IN THE MID LEVELS AS WELL AS SOME MOISTURE SPILLING OVER THE RIDGE. THIS MAY LIMIT COOLING WITH TEMPS POTENTIALLY LEVELING OFF IF SOME OF THESE CLOUDS MATERIALIZE. LOWS TONIGHT WILL BE IN THE IN THE MID/UPPER 30S FOR NYC AND NEARBY SUBURBS...AND IN THE 20S IN OUTLYING AREAS.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... THE CENTER OF THE HIGH DROPS SOUTH OF LONG ISLAND BY MIDDAY THURSDAY. ANY CLOUDS ASSOCIATED WITH THAT MID-LEVEL WARMING WILL DISSIPATE DURING THE MORNING...GIVING WAY TO TO MOSTLY SUNNY SKIES. MEANWHILE...LOW PRES TRACKING ACROSS SOUTHERN CANADA WILL DRAG A COLD FRONT INTO THE GREAT LAKES. THE PRES GRADIENT WILL TIGHTEN DURING THE DAY...AND WITH A 40-50 KT LLJ APPROACHING FROM THE WEST...CAN EXPECT STRONG SW WINDS TO DEVELOP WITH 30-35 KT GUSTS FOR NYC/COASTAL PORTIONS OF NE NJ/WESTERN LONG ISLAND AND 20-25 KT GUSTS ELSEWHERE. STRONG WAA AND DOWNSLOPING EFFECTS WILL PUSH MAX TEMPS INTO THE LOW TO MID 60S FOR NYC AND URBANIZED PORTIONS OF NE NJ...WHILE MOST OF THE CWA WILL TOP OFF IN THE MID TO UPPER 50S. ONLY EXCEPTION WILL BE LONG ISLAND AND COASTAL CT...WHERE THE FLOW COMING OFF THE COLD WATERS WILL KEEP HIGHS ONLY IN THE LOW 50S. HIGH PRES SOUTH OF LONG ISLAND DEPARTS THURSDAY EVENING AND COLD FRONT CONTINUES TO APPROACH FROM THE WEST. THIS WILL PRODUCE SHOWERS ACROSS THE AREA STARTING AFTER MIDNIGHT THURSDAY NIGHT. SINCE LOWS THURSDAY NIGHT WILL BE IN THE MID 40S...PRECIP WILL BE ALL RAIN. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... SHOWERS LIKELY ON FRIDAY WITH THE COLD FRONT APPROACHING...AND ENOUGH ELEVATED INSTABILITY FOR A MENTION OF THUNDER. FOR HIGHS...BLENDED IN COOLER NAM 2M TEMPS WITH MAV/NAM MOS...FIGURING ON RAIN/CLOUDS/AND WIND FLOW OFF THE WATERS FOR AREAS FOR SOME AREAS. LOW LEVEL JET KEEPS PERIODS OF RAIN/SHOWERS FOR FRIDAY NIGHT WITH STILL A THREAT OF A THUNDERSTORM. RELATIVELY HIGHER DEWPOINT AIR MOVING OVER THE COLD WATERS PROBABLY PRODUCES PATCHY/AREAS OF FOG FRIDAY AND FRIDAY NIGHT. COLD FRONT SHOULD BE THROUGH MOST OF THE CWA BY 12Z SATURDAY...SO OUTSIDE OF LOW CHANCES OF SHOWERS EARLY ON...DRY WEATHER WITH CLOUDS DIMINISHING. HIGHS A LITTLE BELOW NORMAL WITH A GUSTY NW WIND. THE FLOW ALOFT SUNDAY THROUGH WEDNESDAY IS FORECAST TO BE GENERALLY ZONAL. THIS WILL WEAKEN A COLD FRONT DROPPING DOWN FROM THE NORTH ON SUNDAY. MODELS DISAGREE WHERE THIS FRONT EVENTUALLY STALLS BEFORE LIFTING BACK NORTH. THIS HAS IMPLICATIONS ON PCPN CHANCES AS WELL AS TEMPERATURES. BEST GUESS CONSIDERING A ZONAL FLOW IS THAT SHOULD THE FRONT PASS COMPLETELY THROUGH THE CWA...IT WILL STALL JUST OFFSHORE TO OUR SOUTH. ECMWF IS APPEARING TO TREND THIS WAY...WHICH IS TOWARDS THE GFS AND GGEM. GIVEN THE UNCERTAINTY...HAVE GONE WITH A PROLONGED PERIOD OF SLIGHT CHC TO CHC POPS SUNDAY AFTN THROUGH WEDS. MUCH OF THE TIME SHOULD BE DRY...BUT THE THREAT OF RAIN SHOULD REMAIN. MIGHT EVEN BE ABLE TO EVENTUALLY REMOVE POPS FOR MONDAY. PCPN TYPE WILL BE RAIN...EXCEPT LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING NORTH OF THE CITY WHERE A MIX OF RAIN AND SNOW WILL BE POSSIBLE. && .AVIATION /02Z THURSDAY THROUGH MONDAY/...
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HIGH PRESSURE BUILDS TONIGHT. THE HIGH TRACKS TO THE EAST AS A WARM FRONT MOVES THROUGH THURSDAY MORNING. VFR THRU THE TAF PERIOD. ISOLATED -SHRA POSSIBLE ACROSS NORTHERN TERMINALS EARLY THU MORNING. WINDS BECOME LIGHT AND VARIABLE THROUGH MIDNIGHT AND BECOME LIGHT S/SW BY MORNING. S/SW WINDS INCREASE ON THURSDAY...PEAKING AT 15 TO 25 KT WITH GUSTS 25 TO 30 LATE THU AFT. WINDS SUBSIDE A BIT AFTER 00Z. .OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY... .THURSDAY NIGHT...DEVELOPING RAIN SHOWERS...WITH MVFR CONDS LATE. SOUTHERLY WINDS OF 15 TO 20 KT WITH HIGHER GUSTS. .FRIDAY-FRIDAY NIGHT...MVFR OR LOWER IN RAIN SHOWERS. WIND FORECAST UNCERTAIN AS FRONT REMAINS NEARBY. .SATURDAY...SUB-VFR POSSIBLE IN SHOWERS EARLY...THEN VFR. GUSTY NW WINDS 20 TO 30 KTS. .SATURDAY NIGHT-SUNDAY...VFR. .SUNDAY NIGHT-MONDAY...MAINLY VFR...BUT CANNOT RULE OUT SUB VFR AT TIMES IN POSSIBLE SHOWERS.
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&& .MARINE... TRANQUIL CONDS THROUGH THURSDAY MORNING AS HIGH PRES BUILDS OVERHEAD TONIGHT AND DROPS SOUTH OF LONG ISLAND BY THURSDAY MORNING. A COLD FRONT SLOWLY APPROACHES FROM THE WEST...AND SMALL CRAFT ADVISORY CONDS DEVELOP ON ALL WATERS BY THURSDAY AFTERNOON AS THE PRES GRADIENT TIGHTENS OVER THE WATERS. A FEW GALE FORCE GUSTS ARE POSSIBLE OVER THE WESTERN ATLANTIC WATERS AS WELL THURSDAY AFTERNOON AND EVENING. SCA CONDS WILL CONTINUE ON THE OCEAN WATERS THROUGH AT LEAST SATURDAY EVENING BEFORE A BRIEF PERIOD OF SUB-SCA CONDS LATE AT NIGHT INTO SUNDAY MORNING. GUSTS TO NEAR GALE FORCE ARE ALSO POSSIBLE DURING SATURDAY AFTERNOON/EARLY EVENING. OTHERWISE... WINDS WILL THEN PICK UP AGAIN SUNDAY AFTERNOON...RETURNING SCA CONDS AS A COLD FRONT SLOWLY DROPS DOWN FROM THE NORTH AND TIGHTENS THE PRESSURE GRADIENT. THIS LOOKS TO BE SHORT-LIVED AS WINDS DIMINISH SUNDAY NIGHT...AND REMAIN BELOW ADVISORY CRITERIA THROUGH MONDAY. FOR THE OTHER WATERS...A COLD FRONT PASSAGE WILL BRING GUSTS OVER 25KT ON SATURDAY...POSSIBLY LINGERING INTO THE EVENING. OTHERWISE...SUB-SCA CONDS FOR THE LONG TERM PERIOD. && .FIRE WEATHER... RELATIVE HUMIDITIES THURSDAY AFTERNOON FALL TO 30-35 PERCENT OVER AREAS MAINLY W OF THE HUDSON...AND WINDS THURSDAY AFTERNOON THERE LIKELY WILL GUST TO 20-25 MPH WITH PEAK GUSTS OF 30-35 MPH POSSIBLE. AT THE MINIMUM THESE CONDITIONS COULD PROMOTE RAPID GROWTH/SPREAD OF ANY FIRES WHICH OCCUR THURSDAY AFTERNOON. && .HYDROLOGY... AROUND AN INCH OF RAIN IS EXPECTED LATE THURSDAY NIGHT THROUGH FRIDAY NIGHT. MINOR URBAN FLOODING IS POSSIBLE...BUT JUST A LOW CHANCE. INCREASED RIVER/STREAM FLOW ACROSS THE LOWER HUDSON VALLEY AND SOUTHERN CONNECTICUT LATE WEEK INTO THIS WEEKEND WILL CONTINUE LOCAL AND UPSTREAM ICE BREAKUP AND MOVEMENT. 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 FROM 2 PM THURSDAY TO 6 AM EDT FRIDAY FOR ANZ330-335-338-340-345-350-353-355. && $$ SYNOPSIS...JC/MPS NEAR TERM...MPS/DS SHORT TERM...MPS LONG TERM...JC AVIATION...NV MARINE...JC/MPS FIRE WEATHER... HYDROLOGY...JC/MPS/NV

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