Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 260302 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1002 PM EST TUE NOV 25 2014 .SYNOPSIS... WEAK HIGH PRESSURE BRIEFLY BUILDS ACROSS THE AREA TONIGHT...WHILE LOW PRESSURE DEVELOPS ALONG THE SOUTHEAST COAST. THE LOW WILL DEEPEN AND TRACK NORTHEAST ON WEDNESDAY...PASSING JUST EAST OF THE SOUTHERN NEW ENGLAND COAST IN THE EVENING. THE LOW THEN TRACKS THROUGH THE CANADIAN MARITIME THURSDAY. HIGH PRESSURE THEN BUILDS IN BEHIND THE DEPARTING LOW FRIDAY AND SATURDAY. LOW PRESSURE MOVES WELL TO THE NORTH AND WEST SUNDAY AND MONDAY...BRINGING A WARM FRONT THROUGH SUNDAY...FOLLOWED BY A COLD FRONT MONDAY. HIGH PRESSURE BUILDS IN TUESDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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CLOUDS INCREASE THROUGHOUT THE NIGHT AS LOW PRES DEVELOPS AND STRENGTHENS OFF THE SOUTHEAST U.S. COAST. SFC DEW POINTS ARE SLOWLY CREEPING UP...BUT IT STILL REMAINS QUITE DRY LOCALLY...AND THERE IS LITTLE...IF ANY...RAIN ALONG THE EASTERN SEABOARD. NEAREST RAIN IS OVER THE CAROLINAS. THEREFORE...IT WILL TAKE SOME TIME FOR MEASURABLE RAINFALL TO REACH NYC AND LONG ISLAND...SO WILL PUSH OFF CHANCE POPS UNTIL JUST PRIOR TO DAYBREAK. TEMPS ACROSS THE INTERIOR HAVE DROPPED INTO THE LOWER 30S...BUT TEMPS THERE SHOULD REBOUND BY A FEW DEGREES OR SO AS CLOUDS SPREAD NORTH. OTHERWISE...LOWS WILL DROP INTO THE MID TO UPPER 30S.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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SIGNIFICANT WINTER STORM WILL TRACK NORTHEAST JUST OFF THE EASTERN SEABOARD ON WEDNESDAY. THERE IS GOOD MODEL AGREEMENT ON TAKING THE LOW JUST INSIDE THE BENCHMARK WED NIGHT...40N...70W. THE REAL DIFFICULT PART OF THE FORECAST IS RESOLVING THERMO PROFILES WITH NO REAL SOURCE OF LOW-LEVEL COLD AIR. EVENT WILL BE HEAVILY DEPENDENT ON DYNAMICAL COOLING AND WHERE BANDING SETS UP. IN ADDITION...ANY DEVIATION RIGHT OR LEFT OF THE LOW TRACK COULD ALTER THERMO PROFILES BY JUST A DEGREE OR TWO...ALL THAT WILL BE NEEDED FOR A SIGNIFICANT CHANGE TO THE FORECAST. HIGHEST CONFIDENCE OF REACHING WARNING LEVEL SNOWS IS ACROSS THE INTERIOR OF SOUTHERN CT...THE LOWER HUDSON VALLEY...AND PORTIONS OF NE NJ. NY METRO AND MUCH OF COASTAL CT HAVE BEEN PLACED INTO AN ADVISORY DUE TO A LONGER TRANSITION TIME TO SNOW AND FREQUENT MIXING WITH RAIN. THIS WILL BE A HEAVY WET SNOW...POTENTIALLY CAUSING POWER OUTAGES AND DOWNED TREE LIMBS. AS PREVIOUSLY MENTIONED...MODELS HAVE COME INTO CONSENSUS WITH A LOW TRACK JUST INSIDE THE BENCHMARK WED EVE. THERE IS NO POLAR AIR IN PLACE FOR LOW-LEVEL COLD AIR WITH THE MODELS VARYING WITH AN ELEVATED WARM LAYER IN THE MID LEVELS. THE 18Z NAM WRF IS THE MOST AGGRESSIVE WITH THIS WARMING WITH 3 DEG C AT 700 MB ACROSS THE NYC METRO. IRONICALLY...THE NAM ABOUT 24 HOURS AGO WAS THE COLDEST SOLUTION WITH A TRACK A BIT FARTHER EAST. IT STILL REMAINS THE COLDEST IN THE BOUNDARY LAYER...WHICH FOR THE MOST PART IS THE HANG UP FOR THE NYC METRO...COASTAL CT...AND WESTERN LI...WHICH ARE GENERALLY BELOW FREEZING ABOVE 1500 FT. THE BOUNDARY LAYER WILL BE CRITICAL HERE. AS FOR THE ELEVATED WARM LAYER FROM THE LATEST NAM...WILL HAVE TO SEE IF THIS SHOWS UP IN THE 00Z CYCLE...PARTICULARLY THE GFS AND ECMWF. THE NAM IS CLEARLY MORE ROBUST WITH AN 85 TO 90 KT JET AT 650 MB. THE ECMWF IS ABOUT 10 TO 15 KT WEAKER AND FARTHER OFFSHORE...AND THE GFS IS EVEN FARTHER EAST. THIS COULD BE HUGE PLAY MAKER. IN ADDITION...WITH A MARGINALLY COLD AIR MASS IN PLACE...850-500 MB FRONTOGENESIS COULD OVERWHELM THE COLUMN WITH SIGNIFICANT SNOWS EVEN INTO THE NYC METRO. FOR NOW WILL KEEP ADVISORY LEVEL SNOWS AT THE COAST AND WARNING LEVEL ACROSS INLAND AREAS. EASTERN LI AND SE CT WILL SEE THE LEAST AMOUNT OF SNOWFALL UNLESS A SIGNIFICANT TRACK CHANGE ENSUES IN SUBSEQUENT CYCLES...WHICH IS NOT LIKELY. PCPN WILL BREAK OUT BY DAYBREAK AND BE HEAVIEST DURING THE MORNING AND AFTERNOON HOURS. HIGHEST SNOWFALL TOTALS WILL RANGE FROM 6 TO 10 INCHES IN THE LOWER HUDSON VALLEY...TO 2 TO 5 INCHES IN THE ADVISORY AREA. STAYED AWAY FROM MOS TEMPS IN THIS SITUATION AND USED THE NAM 2 METER TEMPS FOR BOUNDARY LAYER AND A BLEND OF THE GFS/ECMWF FOR THERMO PROFILES AND PTYPE. TEMPS WILL SLOWLY FALL INTO THE LOWER AND MID 30S BY MID AFT WED. EXPECT A TRANSITION TO ALL SNOW ON THE BACKSIDE WED NIGHT WITH MINOR ADDITIONAL ACCUMULATIONS POSSIBLE. LOWS WILL RANGE FROM THE MID 20S TO LOWER 30S.
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&& .LONG TERM /THURSDAY THROUGH TUESDAY/... AN UPPER TROUGH WILL STILL BE CROSSING THE NORTHEAST THURSDAY INTO THURSDAY EVENING WITH THE SURFACE LOW DEPARTING TO THE NORTHEAST. THERE WILL BE SOME WEAK INSTABILITY ALONG WITH WEAK LIFT WITH THE UPPER TROUGH AND A WEAK SURFACE TROUGH IN THE VICINITY BEHIND THE LOW. BOTH THE GFS AND ECMWF HAVE LIGHT QPF...AND SOME FLURRIES WILL BE POSSIBLE INTO THURSDAY EVENING. THE UPPER TROUGH AXIS MOVES OFF THE COAST THURSDAY NIGHT WITH THE FLOW BECOMING ZONAL INTO EARLY NEXT WEEK. SOME WEAK RIDGING BUILDS TUESDAY AS A DEEPENING TROUGH MOVES INTO THE PACIFIC NORTHWEST AND ROCKY MOUNTAIN RANGE. A VERY WEAK SHORTWAVE MOVE QUICKLY THROUGH THE ZONAL FLOW...NORTH OF THE AREA...SATURDAY NIGHT INTO SUNDAY. A THE SURFACE A WARM FRONT CROSSES THE REGION SUNDAY FOLLOWED BY A COLD FRONT LATE SUNDAY NIGHT INTO MONDAY MORNING. THERE WILL BE A SLIGHT CHANCE OF RAIN SHOWERS SUNDAY INTO MONDAY. FOR TEMPERATURES THURSDAY THROUGH FRIDAY UNDERCUT GUIDANCE BY A FEW DEGREES INLAND WITH THE POTENTIAL OF SNOW COVER AND LIGHT NORTHWEST FLOW. OTHERWISE FOLLOWED WPC GUIDANCE FRIDAY NIGHT THROUGH TUESDAY. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
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***HIGH IMPACT WINTER WEATHER EVENT WEDNESDAY*** LOW PRES WILL TRACK FROM NEAR HATTERAS WED MRNG...TO NEAR CAPE COD WED NGT. VFR MOST OF TNGT...FALLING TO MVFR AS PCPN STARTS AROUND 12Z...TO IFR OR LWR THEREAFTER TIL AFT 00Z WHEN PCPN TAPERS OFF AND CIGS IMPROVE TO MVFR. FOR THE CITY INTO KHPN AND KBDR...PCPN STARTS MAINLY AS RAIN THEN TRANSITIONS TO SNOW BY AROUND 15Z. SLEET AND RAIN MAY THEN MIX IN DURING THE AFTN BEFORE ENDING AS ALL SNOW LATE IN THE AFTN AND INTO THE EVE. FOR KSWF...ALL SNOW. FOR KISP AND KGON...TRANSITION TO SNOW LATER THAN THE CITY...WITH MORE POTENTIAL SLEET AND RAIN MIX IN THE AFTN. POTENTIAL FOR PERIODS OF HVY RAIN. MOST LIKELY RUNWAY ACCUMULATIONS 3-6 INCHES NYC METRO TERMINALS... 8-11 INCHES KSWF/KHPN...3-6 INCHES KBDR...1-2 INCHES KISP/KGON. .OUTLOOK FOR 00Z THU THROUGH SAT... .WED NIGHT...IMPROVERMENT TO MVFR AFT ABOUT 2Z. WINDS BECOMING NW THEN DIMINISHING AFTER MIDNIGHT. .THU-THU NIGHT...LINGERING SNOW SHOWERS POSSIBLE IN THE MORNING WITH MVFR CONDS...THEN VFR. .FRI-SUNDAY...VFR.
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&& .MARINE... A COASTAL LOW BRINGS GALE CONDITIONS TO THE COASTAL OCEAN WATERS WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. THE GALE WARNING REMAINS UNCHANGED. FOR THE REMAINING WATERS...A SCA WILL BE IN EFFECT FOR ROUGHLY THE SAME PERIOD. A NORTHWEST FLOW BEHIND DEPARTING LOW PRESSURE THURSDAY WILL BE BELOW SMALL CRAFT LEVELS...HOWEVER SEAS ON THE OCEAN WILL STILL BE AT SMALL CRAFT LEVELS AND SLOWLY SUBSIDING...FALLING BELOW BY FRIDAY MORNING AS HIGH PRESSURE BUILDS IN. THEN WIND AND SEAS WILL REMAIN BELOW SMALL CRAFT THE REMAINDER OF FRIDAY INTO SATURDAY. A RETURN FLOW DEVELOPS SATURDAY AS THE HIGH MOVES OFF THE COAST. A SOUTHWEST FLOW INCREASES AS LOW PRESSURE MOVES THROUGH THE GREAT LAKES REGION SATURDAY INTO SUNDAY. SOME GUSTS ON THE OCEAN WATERS MAY BE NEAR SMALL CRAFT LATER SATURDAY INTO SUNDAY...AND SEAS WILL BE BUILDING TO SMALL CRAFT LATE SATURDAY AND REMAIN INTO SUNDAY. && .HYDROLOGY... FOR WEDS AND WEDS NIGHT...EXPECTING A LIQUID EQUIVALENT PRECIPITATION AMOUNTS AVERAGING AROUND 1.0 TO 1.5. THE HIGHEST QPF AMOUNTS AREA CURRENTLY EXPECTED OVER EASTERN CT/LONG ISLAND AND THE LOWEST OVER FAR WESTERN PORTIONS OF THE TRI-STATE. OVER THE INTERIOR MOST OF THIS WILL FALL IN THE FORM OF SNOW...SO LITTLE IF ANY IMMEDIATE HYDROLOGIC IMPACT IS EXPECTED THERE. FARTHER TO THE S/E...BASICALLY ALONG AND E OF I-95...THERE WILL BE A A MIX OF RAIN AND SNOW. THIS COULD CAUSE MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS. THURSDAY THROUGH SUNDAY...VERY LIGHT QPF AMOUNTS ARE POSSIBLE...THURSDAY...SATURDAY AND SUNDAY. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR CTZ005>007. WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR CTZ008>011. NY...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR NYZ067>070. WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR NYZ071>075-176>178. NJ...WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR NJZ002-004-103-105-107. WINTER WEATHER ADVISORY FROM 7 AM WEDNESDAY TO 1 AM EST THURSDAY FOR NJZ006-104-106-108. MARINE...SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO 1 AM EST THURSDAY FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 11 AM EST WEDNESDAY FOR ANZ350-353- 355. GALE WARNING FROM 11 AM WEDNESDAY TO MIDNIGHT EST WEDNESDAY NIGHT FOR ANZ350-353-355. && $$ SYNOPSIS...MET/DW NEAR TERM...MPS SHORT TERM...MPS LONG TERM...MET AVIATION...JMC/GOODMAN MARINE...MET/DW HYDROLOGY...MET/DW

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