Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 262247 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 647 PM EDT THU MAR 26 2015 .SYNOPSIS... A COLD FRONT WILL PASS TONIGHT. LOW PRESSURE WILL DEVELOP OFFSHORE FRI NIGHT...AND TRACK TOWARDS THE MARITIMES SATURDAY. AN UPPER LEVEL DISTURBANCE MOVES ACROSS SATURDAY AND MOVES EAST OF THE REGION SATURDAY NIGHT. HIGH PRESSURE BUILDS IN THEREAFTER. FOR THE NEW WORK WEEK...A SERIES OF CLIPPER LOWS WILL BE MOVING ACROSS. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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BREAK IN THE AREA OF SHOWERS ACROSS THE WESTERN PORTION OF THE REGION AND ADJUSTED POPS AND WEATHER TO REFLECT THE CURRENT CONDITIONS. SHOWERS AND ISOLATED THUNDERSTORMS WILL MOVE INTO THE WESTERN ZONES THIS EVENING...AHEAD OF THE COLD FRONT...AND RAISED POPS 00Z TO 02Z. LINE OF THUNDERSTORMS ACROSS SOUTHEASTERN PENNSYLVANIA EXPECTED TO WEAKEN AS THE LINE MOVES INTO MORE STABLE AIR AHEAD OF THE WARM FROM WHICH IS THROUGH CENTRAL NEW JERSEY. DENSE FOG INVOF THE FRONT...WITH THE NARRE SUGGESTING WIDESPREAD DENSE FOG LI AND CT BEFORE THE CDFNT ACROSS UPSTATE NY PASSES LATE TNGT. HAVE ISSUED A DENSE FOG ADVY AS A RESULT. THERE IS ALREADY PATCHY DENSE FOG ACROSS THE AREA...AND A COOLING BL THIS EVE SHOULD ALLOW FOR EXPANSION. MAIN LIMITING FACTOR COULD BE GUSTY SLY WINDS IN THE WARM SECTOR. OTHERWISE...WAA SHWR AND TSTMS EXITING THE CWA TO THE NE. MAIN BAND OF PCPN WITH THE CDFNT GETS HERE TNGT. MAINTAINED ISOLD TSTMS WITH THE FROPA AS THERE WAS SOME LIGHTNING ACTION UPSTREAM TODAY.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... THE FRONT EXITS THE AREA BUT THE APPROACHING UPR JET COULD SUSTAIN LGT RAIN AT LEAST INTO THE MRNG. FOCUS THEN TURNS TO DEVELOPING LOW PRES OFFSHORE AS THE H5 SHTRWV APPROACHES. THE NAM HAD HINTED AT THIS YESTERDAY...AND NOW THE GFS...ALTHOUGH THE LONE SOLN WITH THE 12Z SUITE...HAS LATCHED ON. THIS WOULD BRING PCPN IN LATE FRI AFTN/EVE...THEN SPREADING WWD FRI NGT. AT THE SAME TIME...THE PCPN WOULD TRANSITION TO SNOW OVERNIGHT AS THE COLD UPR TROF MOVES IN. WITH NLY COMPONENT FLOW...THIS CHANGEOVER WOULD OCCUR EVEN DOWN TO THE COASTS. HAVE INCLUDED CHC POPS FOR THIS EVENT...HOWEVER THE ECMWF AND NAM SOLNS WOULD LEAVE THE AREA WITH BENIGN WX. && .LONG TERM /SATURDAY THROUGH THURSDAY/... RELATIVELY ACTIVE WEATHER PATTERN WILL BE PRESENT FOR THE WEEKEND THROUGH EARLY NEXT WEEK. THIS IS DIAGNOSED BY SHARPER AND LESS WAVELENGTH OF TROUGHS AND CORRESPONDING RIDGES. BY MID TO LATE NEXT WEEK...THERE IS A LONGER WAVELENGTH AND HENCE CLOSER TO A ZONAL TYPE OF FLOW OCCURRING WHICH WILL BE LESS AMPLIFIED. THE MAIN UPPER JET WILL BE SOUTH OF THE REGION FOR THE WEEKEND BEFORE LIFTING BACK NORTH OVER THE AREA AND BECOMING MORE BROAD WITH LESS WIND SPEED FOR LATER NEXT WEEK. AT THE SURFACE...ONE FEATURE TO FOCUS ON IS A LOW DEVELOPING ALONG AN OFFSHORE COLD FRONT SATURDAY. THE CENTER OF THE LOW DEPENDING ON THE MODEL CHOSEN...IS APPROXIMATELY NEAR THE 40N AND 65W COORDINATES. THE GFS IS MOST PROGRESSIVE WITH THIS LOW...MOVING IT FASTER TO THE NORTHEAST INTO THE CANADIAN MARITIMES WHILE THE ECMWF...NAM...AND CMC ARE REMARKABLY SLOWER. ONCE THE LOW PUSHES FARTHER INTO THE CANADIAN MARITIMES SATURDAY NIGHT...THEN HIGH PRESSURE...ORIGINATING FROM CENTRAL CANADA...WILL GAIN MORE INFLUENCE AS IT BUILDS IN FROM THE WEST. THE RIDGE OF HIGH PRESSURE MOVES ACROSS SUNDAY AS THE CENTER OF HIGH PRESSURE MOVES INTO THE SOUTHEAST. A FAST MOVING CLIPPER LOW APPROACHES SUNDAY NIGHT...MOVING ACROSS THE REGION MONDAY. THIS WILL BE FOLLOWED BY HIGH PRESSURE MONDAY NIGHT INTO EARLY TUESDAY BEFORE ANOTHER QUICK MOVING CLIPPER LOW MOVES IN TUESDAY NIGHT. HIGH PRESSURE RETURNS BEHIND IT LEADING INTO EARLY THURSDAY BEFORE YET ANOTHER CLIPPER MOVES IN. IN TERMS OF WEATHER...OVERALL COOLER THAN NORMAL TEMPERATURES WILL CONTINUE. THIS WILL BE MOST PRONOUNCED THIS WEEKEND WITH FORECAST HIGHS ONLY REACHING THE UPPER 30S TO LOWER 40S. THERE WILL BE A FEW PERIODS TO WATCH FOR PRECIPITATION. THE HIGHEST CHANCES ARE SATURDAY BEHIND THE COLD FRONT ASSOCIATED WITH DEFORMATION TO THE WEST OF THE OFFSHORE DEEPENING LOW. QUITE THE UNCERTAINTY HERE WITH NAM AND ECMWF SHOWING LITTLE TO NO PRECIPITATION WHILE CMC AND GFS SHOW A LIGHT AMOUNT OF PRECIPITATION...GENERALLY LESS THAN A QUARTER OF AN INCH. CURRENT FORECAST TAKES INTO ACCOUNT AN AVERAGE OF ALL MODEL SOLUTIONS...WITH GENERALLY LESS THAN 1 INCH OF SNOW AND WITH TEMPERATURES ABOVE FREEZING...A LOT DEPENDS ON HOW MUCH DYNAMIC COOLING TAKES PLACE AS WELL AS THE INTENSITY OF THE SNOW AS FAR AS HOW MUCH SNOW ACCUMULATES ON THE GROUND. OTHER CHANCES FOR PRECIP WILL BE MORE IN THE NATURE OF RAIN AND SNOW SHOWERS LATE SUNDAY NIGHT INTO MONDAY AS WELL AS TUESDAY NIGHT INTO WEDNESDAY. YET ANOTHER CHANCE OF SHOWERS FOR NEXT THURSDAY. THESE ARE ALL ASSOCIATED WITH FAST MOVING CLIPPER LOWS. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/...
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A WARM FRONT WILL BECOME STATIONARY OVER THE AREA LATE THIS AFTERNOON. A COLD FRONT WILL THEN MOVE ACROSS TONIGHT. IFR/LIFR CONDS AND LLWS ARE AT MOST TERMINALS...BUT KJFK/KLGA/KBDR HAVE BRIEFLY GONE MVFR. KJFK/KISP ARE SOUTH OF THE FRONT AND GUSTING TO 25-30 IN S FLOW...AND KLGA MAY FOLLOW SUIT TOWARD EVENING. ONSHORE FLOW SHOULD EVENTUALLY BRING A RETURN TO IFR/LIFR CONDS TO ALL TERMINALS BEFORE COLD FROPA THIS EVENING...BY 03Z AT THE NYC METRO TERMINALS AND 04Z FARTHER EAST. SFC WINDS SHOULD VEER SW AND DIMINISH FOR A COUPLE OF HRS BEFORE FROPA...THEN SHIFT NNW AND DIMINISH TO 10 KT OR LESS. THERE IS SOME UNCERTAINTY AS TO FLIGHT CAT AFTER FROPA LATER TONIGHT INTO FRI MORNING...ATTM DECIDED TO SIDE WITH MORE PESSIMISTIC GUIDANCE BUT THERE COULD BE PERIODS OF 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: UNSCHEDULED AMD POSSIBLE FOR CHANGES IN FLIGHT CATEGORY. COLD FROPA BY 03Z...BUT IFR CONDS COULD PERSIST UNTIL 05Z-06Z. KLGA FCSTER COMMENTS: UNSCHEDULED AMD POSSIBLE FOR CHANGES IN FLIGHT CATEGORY. COLD FROPA BY 03Z...BUT IFR CONDS COULD PERSIST UNTIL 05Z-06Z. KEWR FCSTER COMMENTS: UNSCHEDULED AMD POSSIBLE FOR CHANGES IN FLIGHT CATEGORY. COLD FROPA BY 02Z-03Z...BUT IFR CONDS COULD PERSIST UNTIL 05Z-06Z. KTEB FCSTER COMMENTS: UNSCHEDULED AMD POSSIBLE FOR CHANGES IN FLIGHT CATEGORY. COLD FROPA BY 02Z-03Z...BUT IFR CONDS COULD PERSIST UNTIL 05Z-06Z. KHPN FCSTER COMMENTS: UNSCHEDULED AMD POSSIBLE FOR SIGNIFICANT CHANGES IN FLIGHT CATEGORY. KISP FCSTER COMMENTS: UNSCHEDULED AMD POSSIBLE FOR CHANGES IN FLIGHT CATEGORY. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRI AFTERNOON...BECOMING VFR. .FRI NIGHT-SAT...CHANCE OF MVFR CONDS WITH ANY RAIN OR SNOW SHOWERS. N WINDS G15-20KT. .SAT NIGHT-.SUNDAY NIGHT...VFR. .MON...VFR. SW WINDS 15G20KT...BECOMING WNW AT NIGHT. .TUE...VFR. NW WINDS 15-20G25-30KT...DIMINISHING AT NIGHT.
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&& .MARINE...
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WITH THE WARM FRONT IN THE VICINITY OF THE FORECAST WATERS...AND THE COLD FRONT APPROACHING EARLY THIS EVENING...EXPECT SHOWERS AND ISOLATED THUNDERSTORMS TO REMAIN OVER THE WATERS. UPDATED WEATHER THROUGH THIS EVENING. WIDESPREAD DENSE FOG WILL REMAIN UNTIL THE COLD FRONTAL PASSAGE. SCA REMAINS IN EFFECT FOR SRN WATERS WITH GUSTY SLY FLOW AND BUILDING SEAS ON THE OCEAN. POTENTIAL OF OCNL SCA GUSTS ON THE SOUND IF THE FRONT MAKES IT THRU. AREAS OF DENSE FOG ALSO LIKELY TIL MIDNIGHT...THEN THE PASSAGE OF A CDFNT DISSIPATES IT LATE. SCA COND REMAIN ON THE OCEAN FRI...AND WILL LIKELY NEED TO BE EXTENDED AT LEAST THRU FRI NGT. SCA POSSIBLE SATURDAY THROUGH EARLY SUNDAY AS WELL AS LATE SUNDAY NIGHT THROUGH MONDAY NIGHT. THE NEXT CHANCE FOR SCA IS TUESDAY NIGHT. THE SCA CHANCES WILL BE MAINLY ACROSS THE OCEAN AND EASTERN WATERS. OTHERWISE...SUB SCA CONDITIONS ARE FORECAST FOR THE LONG TERM FORECAST THIS WEEKEND AND NEXT WEEK OUTSIDE OF THE AFOREMENTIONED TIME PERIODS.
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&& .HYDROLOGY...
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A HALF INCH OR LESS OF PCPN IS EXPECTED INTO FRI MRNG. NO SIGNIFICANT WIDESPREAD PRECIPITATION OTHERWISE EXPECTED ATTM. CURRENTLY RIVERS AND STREAMS ARE EXPECTED TO REMAIN BELOW BANK FULL...BUT THE MILD TEMPS AND INCREASED RIVER/STREAM FLOW WILL INCREASE ICE BREAKUP AND MOVEMENT DURING THE NEXT FEW DAYS. 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.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...DENSE FOG ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR CTZ005>012. NY...DENSE FOG ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR NYZ078>081- 177-179. NJ...NONE. MARINE...DENSE FOG ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ330-335- 340-345-350-353-355. SMALL CRAFT ADVISORY UNTIL 6 PM EDT FRIDAY FOR ANZ350-353-355. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ345. && $$ SYNOPSIS...JMC NEAR TERM...JMC/MET SHORT TERM...JMC LONG TERM...JM AVIATION...GOODMAN MARINE...JMC/JM/MET HYDROLOGY...JMC/JM

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