Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 292053 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 453 PM EDT TUE JUL 29 2014 .SYNOPSIS... WEAK HIGH PRESSURE SLOWLY BUILDS OFFSHORE THROUGH WEDNESDAY NIGHT. A FRONTAL BOUNDARY OVER THE WESTERN ATLANTIC ON THURSDAY WILL GRADUALLY WORK WEST TOWARD THE COAST THROUGH THIS WEEKEND WITH MULTIPLE WAVES OF LOW PRESSURE TRACKING ALONG IT. WEAK HIGH PRESSURE WILL THEN RETURN EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... INSTABILITY CLOUDS SHOULD GRADUALLY DISSIPATE...WITH DEVELOPING INVERSION FROM AROUND 750-650 HPA SERVING AS A LIMITING FACTOR. GIVEN EXPECTED CLOUD COVER LINGERING INTO THE NIGHT...WEIGHED TEMPERATURE FORECAST TOWARDS WARMER MET GUIDANCE FOR LOWS. TO ACHIEVE THIS USED A BLEND OF THE PREVIOUS FORECAST...NAM 2-METER TEMPERATURES AND A BLEND OF MAV/MET GUIDANCE. LOWS SHOULD BE AROUND 5 DEGREES BELOW NORMAL. THERE IS A MODERATE RISK FOR THE METEOROLOGICAL ENHANCEMENT OF RIP CURRENTS EARLY THIS EVENING AT AREA OCEAN BEACHES. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... THERE IS QUITE A BIT OF SPREAD IN THE MODELS WHETHER THERE WILL BE SUFFICIENT LOW-MID LEVEL INSTABILITY AND PASSING OF WEAK 700-500 HPA SHORTWAVE WILL PROMOTE SPRINKLES TO MAYBE ISOLD SHRA/TSTM ACROSS INTERIOR ZONES WEDNESDAY. THE NAM IS THE MOST BULLISH FOLLOWED BY THE SREF...THE ECMWF IS DRY AND THE CMC REG AND GFS SUGGEST LIMITING TO WESTERN ORANGE COUNTY. BUFKIT SOUNDINGS SUGGEST THAT THE THE MID LEVEL CAP THAT DEVELOPS MIGHT NOT ERODE...EVEN OVER ORANGE COUNTY. THUS...FOR NOW HAVE OPTED FOR A DRY FORECAST FOR WEDNESDAY FOR ALL BUT THE NW 1/2 OF ORANGE COUNTY...WHERE HAVE GONE WITH SLIGHT CHANCE POPS. HOWEVER...WITH WET BULB ZERO HEIGHTS AROUND 7500-8500 FT...AND 500 HPA TEMPERATURES AROUND -15C IT SHOULD NOT TAKE TO MUCH CLOUD DEPTH TO GET LIGHTNING AND/OR SMALL HAIL/GRAUPEL...SO WENT WITH A SLIGHT CHANCE OF THUNDER THERE AS WELL. ELSEWHERE ACROSS THE INTERIOR...WHERE THE CAP IS FORECAST TO BE A BIT STRONGER THAN OVER NW ORANGE COUNTY...THE QUESTION IS ARE LOW LEVEL LAPSE RATES STRONG ENOUGH TO PROMOTE SPRINKLES UNDER THE CAP. IF THIS WERE THE COOL SEASON WOULD BE INCLINED TO SAY YES...BUT NOT CONFIDENT ENOUGH TO DO SO IN THE WARM SEASON...AS MODELS ON OCCASION OVERDO THE AMOUNT OF LOW LEVEL INSTABILITY DURING THIS TIME OF YEAR. ELSEWHERE WOULD EXPECT TO SEE SOME INSTABILITY CLOUDS LIKE TODAY...SO HAVE LOWERED HIGHS A TAD FROM THE PREVIOUS FORECAST...CONSISTENT WITH A BLEND OF MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES AND MIXING DOWN FROM 875 HPA...EXCEPT 850 HPA NW ZONES PER BUFKIT SOUNDINGS. HIGHS SHOULD BE A FEW DEGREES BELOW NORMAL. WITH WEAK SHORTWAVE EXITING TO THE NE AND MID LEVEL INVERSION WEAKER THAN TONIGHT...WOULD EXPECT CLOUDS TO DISSIPATE DURING THE EVENING...SO DO EXPECT SOME RADIATIONAL COOLING WEDNESDAY NIGHT. BASED ON THIS USED A BLEND OF MAV/MET GUIDANCE WITH NAM 2-METER TEMPERATURES FOR LOWS...WITH VALUES A FEW DEGREES BELOW NORMAL. && .LONG TERM /THURSDAY THROUGH TUESDAY/... A HIGHLY AMPLIFIED ANOMALOUS SUMMERTIME PATTERN FEATURES A TROUGH ACROSS EASTERN NORTH AMERICA...WITH RIDGING OUT WEST AND ACROSS THE WESTERN ATLANTIC. THIS BLOCKING PATTERN WILL RESULT IN THE AFOREMENTIONED TROUGH GRADUALLY FILLING AND WORKING EAST AT THE END OF THE PERIOD AS AN UPSTREAM KICKER MOVES INTO CENTRAL CANADA. THERE ARE CLEARLY TIMING DIFFERENCES AMONGST THE GLOBAL MODEL SUITE WITH HOW QUICKLY THIS OCCURS...AS WELL AS WITH AN OFFSHORE FRONTAL BOUNDARY THAT RETROGRADES WEST IN RESPONSE TO HEIGHT RISES ALONG THE EASTERN SEABOARD THU INTO SAT. THE LATTER OF WHICH COULD BRING A BOUT OF STEADY RAINS INTO THE REGION FRI NIGHT INTO THE SAT. THE 12Z ECMWF AND 12Z GGEM REMAIN THE MOST AGGRESSIVE SOLUTIONS. THE POTENTIAL IS THERE FOE A SIGNIFICANT RAINFALL EVENT...BUT THERE REMAINS A DECENT AMOUNT OF UNCERTAINTY WITH THE LOCATION OF THE FRONTAL WAVE AND THE BOUNDARY. FOR THU INTO FRI...HIGH PRESSURE WILL BE SITUATED TO THE EAST WITH A RETURN SLY FLOW. AIRMASS REMAINS FAIRLY DRY IN THE LOW-LEVELS WITH ONLY MARGINAL INSTABILITY AND WEAK TO MODERATE SHEAR. OVERALL CHANCES FOR CONVECTION ARE LOW DURING THIS TIME WITH THE BEST CHANCES BEING IN THE AFT/EVE HOURS IN THE HILLS NW OF NYC...DRIVEN BY DIFFERENTIAL HEATING. RAIN CHANCES THEN INCREASE WITH THE APPROACH OF THE OFFSHORE FRONT AND MULTIPLE WAVES OF LOW PRESSURE. ONCE AGAIN THOUGH...THE SOLUTIONS VARY ON THE PROXIMITY OF THE FRONT. FOR EARLY NEXT WEEK...WEAK HIGH PRESSURE WILL BUILD IN ON THE HEELS OF THE DEPARTING UPPER TROUGH. THE GGEM AND GFS BOTH ARE SLOWER WITH THE PROGRESSION OF THE TROUGH. THUS...CONVECTION COULD LINGER INTO MON WITH A WEAK TROUGH/COLD FRONT MOVING THROUGH. TEMPS SHOULD BE NEAR AVG THU-FRI...THEN A LITTLE BELOW AVG THIS WEEKEND VIA CLOUD COVER AND GREATER POP...THEN RETURNING TO NEAR AVG ON MON. HUMIDITY LEVELS WILL ALSO NE ON THE INCREASE WITH DEW POINTS RISING INTO THE 60S. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/...
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SURFACE TROUGH REMAINS EAST OF THE CITY TERMINALS. NW TO W WINDS FOR THE CITY TERMINALS AND POINTS WEST. KISP AND KBDR MAY EXPERIENCE A COUPLE OF WIND SHIFTS WITH THE SEA BREEZE BOUNDARY REMAINING NEARBY. SLIGHT CHANCE OF THIS OCCURRING AT JFK AS WELL. VRB WINDS 5 KT OR LESS AT ALL TERMINALS FROM 03-05Z THROUGH WEDNESDAY MORNING. SEA BREEZES QUICKLY DEVELOP LATE WEDNESDAY MORNING. ..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 FORECASTER COMMENTS: OCCASIONAL GUSTS 16-19KT THRU 00Z. CHANCE THAT SEA BREEZE PUSHES THROUGH WITH A SSW WIND SHIFT SOMEWHERE IN THE 00Z-02Z TIME FRAME. KLGA FORECASTER COMMENTS: OCCASIONAL GUSTS 16-19KT POSSIBLE THRU 00Z TIMING OF WINDS BACKING WNW COULD BE OFF BY AN HOUR OR TWO. WINDS MIGHT NOT BACK TO AROUND 300 MAGNETIC AND REMAIN AT OR NORTH OF 310 MAGNETIC THROUGH EARLY EVENING. KEWR FORECASTER COMMENTS: GUSTS MIGHT BE ONLY OCCASIONAL. WINDS COULD BE BACKED TO 260-280 MAGNETIC AT TIMES BEFORE 23Z. KTEB FORECASTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FORECASTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FORECASTER COMMENTS: SEA BREEZE COULD RETURN NORTH AND SHIFT WINDS 240-210 MAGNETIC AS EARLY AS 23Z. .OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY... .WEDNESDAY...VFR. ISOLATED SHOWERS/TSTMS POSSIBLE AT KSWF IN THE AFTERNOON. .THURSDAY-FRIDAY...ISOLATED SHOWERS/TSTMS POSSIBLE IN THE AFTERNOON/EARLY EVENING...MAINLY WEST OF A LINE FROM KBDR TO KFRG. VFR OUTSIDE OF ANY SHOWERS/TSTMS. .SATURDAY-SUNDAY...MAINLY VFR...SUB-VFR CONDITIONS POSSIBLE IN SCT SHOWERS.
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&& .MARINE... WINDS WILL BE 10 KT OR LESS ON THE WATERS AROUND LONG ISLAND THROUGH WEDNESDAY NIGHT. SEAS ON THE COASTAL OCEAN WATERS WILL BE 4 FT OR LESS AND ON THE REMAINDER OF THE WATERS 1 FT OR LESS AS A RESULT THROUGH WEDNESDAY NIGHT. CONDITIONS SHOULD REMAIN QUIET FROM THURSDAY THOUGH EARLY NEXT WEEK WITH AN APPROACHING OFFSHORE FRONT THIS WEEKEND AND THEN WEAK HIGH PRESSURE EARLY NEXT WEEK. && .HYDROLOGY... IT SHOULD BE MAINLY DRY THROUGH WEDNESDAY NIGHT. NO SIGNIFICANT RAINFALL IS THEN EXPECTED FROM THURSDAY THROUGH FRIDAY. PARTS OF THE AREA...ESPECIALLY CLOSER TO THE COAST...HAVE THE POTENTIAL FOR HEAVY RAIN FRIDAY NIGHT AND THIS WEEKEND...DEPENDING ON THE POSITION OF AN OFFSHORE FRONTAL ZONE AND TIMING OF ANY ASSOCIATED WEAK WAVES OF LOW PRESSURE. THIS POTENTIAL IS STILL SEVERAL DAYS AWAY...SO IT IS TOO EARLY TO OFFER SPECIFIC FORECAST DETAILS OR TO MENTION IN HWO. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...MALOIT/DW NEAR TERM...MALOIT SHORT TERM...MALOIT LONG TERM...DW AVIATION...JC/MPS MARINE...MALOIT/DW HYDROLOGY...MALOIT/DW

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