Area Forecast Discussion
Issued by NWS Upton, NY

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459 FXUS61 KOKX 040523 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1223 AM EST THU FEB 4 2016 .SYNOPSIS...
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A COLD FRONT MOVES ACROSS THE REGION OVERNIGHT INTO EARLY THURSDAY MORNING. LOW PRESSURE WILL DEVELOP ALONG THIS FRONT OFF THE MID ATLANTIC COAST AND TRACK NORTHEAST PASSING OFFSHORE FRIDAY. HIGH PRESSURE MOVES EAST ACROSS THE AREA THROUGH SUNDAY FOLLOWED BY IMPACTS FROM POTENTIAL COASTAL STORMS MONDAY THROUGH TUESDAY.
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&& .NEAR TERM /THROUGH TODAY/...
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UPDATED FOR TEMPERATURES AND DEW POINTS AT THIS TIME. THE REMAINDER OF THE FORECAST FOR THE OVERNIGHT REMAINS. BASED ON LATEST HRRR...CAN EXPECT ANOTHER ROUND OF SHOWERS WITH PASSAGE OF COLD FRONT LATE IN THE OVERNIGHT PERIOD AND TOWARDS DAYBREAK. WEAK LOW PRES WILL PASS WELL EAST OF THE THURSDAY MORNING...AND WILL CARRY HIGHER POPS FOR THE EASTERN PORTION OF THE CWA. WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE...CAN EXPECT AREAS OF FOG ACROSS THE REGION. TEMPS WILL REMAIN WELL ABOVE NORMAL TONIGHT WITH LOWS 40-50 DEGREES. A WEAK HIGH PRESSURE RIDGE BEHIND THE FRONT WILL ALLOW DRIER AIR TO FILTER ACROSS THE REGION THURSDAY WITH DAY TIME HIGHS IN THE 50S.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM FRIDAY/... POTENTIAL FOR AN ACCUMULATING WET SNOW AFTER MIDNIGHT THURSDAY THROUGH FRIDAY MORNING MAINLY EAST OF NYC ACROSS LONG ISLAND AND SOUTHERN CT. MODELS SHOW AN AMPLIFYING SHORT WAVE DIGGING SE AND BECOMING SLIGHTLY NEGATIVE...ALLOWING LOW PRES TO DEVELOP CLOSER TO THE COAST THU NIGHT AND ITS ASSOCIATED PRECIP SHIELD TO EXPAND FURTHER NORTH AND WEST THAN PREVIOUS FORECASTS. ALTHOUGH THERMAL PROFILES ARE MARGINAL AS THE PRECIP DEVELOPS AFTER MIDNIGHT THU NIGHT...THE ATMOSPHERE DOES COOL AND LIGHT RAIN..QUICKLY MIXES WITH AND CHANGES TO SNOW. BEFORE THE SNOW ENDS FRIDAY MORNING... THE MOST LIKELY FCST...1-3 INCHES ACROSS LONG ISLAND AND SE CT WITH LESS THAN 1 INCH FOR NYC. THE FORECAST UNCERTAINTY... A SHIFT IN THE TRACK FURTHER WEST COULD RESULT IN UP TO 3-6 INCHES ACROSS LONG ISLAND AND SOUTHERN CT WITH HIGH IMPACT DURING THE FRIDAY MORNING COMMUTE. A SHIFT FURTHER EAST...A DUSTING OF LESS THAN 1 INCH OR NO SNOW. STAY TUNED. A WINTER WEATHER ADVISORY IS NOT OUT OF THE QUESTION FOR THIS POTENTIAL EVENT. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... NWP MODEL SUITE IS IN GOOD AGREEMENT WITH THE H5 FLOW INTO THE WEEKEND...BUT THEN DIFFERENCES WITH TIMING AND AMPLITUDE DEVELOP LEADING TO LOW CONFIDENCE IN THE FORECAST DETAILS FOR THE FIRST HALF OF NEXT WEEK. THIS IS ALSO APPARENT IN THE SUNY SB ENSEMBLE SENSITIVITY ANALYSIS WHICH IS INDICATING VARIABILITY IN THE AMPLIFICATION OF THE H5 FLOW BEGINNING FRI. THIS IS THE REASON WHY THE FORECAST FOR EARLY NEXT WEEK REMAINS UNCERTAIN. A SPLIT FLOW ACROSS EASTERN NOAM WILL START THE FORECAST PERIOD...GIVING WAY TO A DIGGING TROUGH EARLY NEXT WEEK AS A HIGH AMPLITUDE RIDGE BUILDS OUT WEST. THIS WILL TRANSLATE TO PROGRESSIVELY COLDER TEMPERATURES BY THE MIDDLE OF NEXT WEEK. AT THE SFC...HIGH PRES BUILDS OVER THE MID ATLANTIC STATES FRI NIGHT AND WEAKENS AS IT SLIDES OFFSHORE ON SAT. A WEAKENING COLD FRONT APPROACHES SAT NIGHT...MOVING THROUGH DRY ON SUN. MEANWHILE...THE SOUTHERN STREAM WILL BE CUTTING OFF OVER THE SOUTHEAST STATES WITH CYCLOGENESIS OCCURRING OFF THE COAST SAT NIGHT. THE MODELS HAVE CONSISTENTLY BEEN TRACKING THIS SYSTEM WELL OUTSIDE OF THE 40N 70W BENCHMARK. ALTHOUGH THE 12Z/03 ECMWF IS NOW THROWING SOME QPF BACK INTO AREAS E OF NYC...FEEL THIS IS OVERDONE...AND HAVE KEPT THE FORECAST DRY FOR MON. IF THE TRACK SHIFTS BACK TO THE WEST ONCE BETTER SAMPLING OF THE ENERGY ASSOCIATED WITH THIS SYSTEM IS CAPTURED WHEN IT MOVES ONSHORE...THEN POPS WOULD NEED TO BE RAISED. THE NEXT COASTAL STORM IS SLATED FOR LATE MON NIGHT INTO TUE NIGHT. THIS TRACK OF THIS SYSTEM HAS BEEN ALL OVER THE PLACE THE LAST FEW DAYS AND IS ALSO IMPACTED BY THE LACK OF DATA AVAILABLE OVER THE PACIFIC. DECIDED IT WAS BEST TO STICK WITH CONTINUITY UNTIL THINGS CAN BE BETTER RESOLVED AND HAVE NOT MADE MUCH CHANGE TO THE FORECAST DURING THIS TIME. HOWEVER...THE SIGNAL FOR A MILLER TYPE B STORM REMAINS...BUT TIMING...STRENGTH AND P-TYPE REMAIN UNCERTAIN. THINGS DRY OUT ON WED...ALTHOUGH COULD SEE SOME LAKE EFFECT ACROSS NW ZONES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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A COLD FRONT WILL SLOWLY PASS THROUGH THE AREA THIS MORNING STALLING SOUTHEAST OF THE TERMINALS DURING THE AFTERNOON. VFR CONDITIONS HAVE RETURNED FOR MANY TERMINALS AS THE RAIN EXITS TO THE EAST. EXPECT CONDITIONS TO DETERIORATE TO MVFR OR IFR OVERNIGHT. A FEW SHOWERS MAY DEVELOP AHEAD OF THE FRONT...SO ADDITIONAL RAIN CANNOT BE RULED OUT THROUGH 12-13Z. ONCE THE FRONT SLOWLY MOVES THROUGH...CONDITIONS SHOULD IMPROVE TO VFR BY 12-14Z...A BIT LATER FURTHER EAST. BY TONIGHT...A WAVE DEVELOPS ON THE STALLED FRONT...AND RAIN MAY MOVE IN ACROSS TERMINALS EAST OF NYC METRO. LIGHT SW/S WINDS TURN TO THE WEST...THEN NW THIS MORNING. TIMING AROUND 12Z FOR THE WEST SHIFT...AND 14Z FOR THE NW SHIFT. SPEEDS INCREASE TO AROUND 10 KTS. CANNOT RULE OUT A FEW AFTERNOON GUSTS TO 15 TO 20 KTS...BUT THESE SHOULD BE INFREQUENT NW WINDS DIMINISH TEMPORARILY BY EVENING...BUT INCREASE FROM THE N LATE EVENING. .OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY... .LATE TONIGHT-FRIDAY...SUB-VFR IS POSSIBLE...MAINLY EAST OF NYC METRO IN LIGHT SNOW. WNW-NW WINDS G15-20 KT POSSIBLE DURING THE DAY FRIDAY. .FRIDAY NIGHT-MONDAY...VFR. SW WINDS G15-20KT POSSIBLE DURING THE DAY ON SATURDAY.
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&& .MARINE...
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WITH WIND GUSTS BELOW SMALL CRAFT LEVELS ACROSS LONG ISLAND SOUND AND THE LONG ISLAND BAYS ALLOWED THE ADVISORY TO EXPIRE AT 05Z. THE SMALL CRAFT REMAINS ON THE OCEAN WATERS...MAINLY FOR SEAS...WITH A FEW GUSTS AROUND 25 KT. SMALL CRAFT ADVISORIES REMAIN IN EFFECT ON THE OCEAN WATERS. WITH SEAS EXPECTED TO REMAIN 6-9 FT FOR AT LEAST THE NEXT 3 PERIODS...WILL RUN THE SCA THROUGH LATE THURSDAY NIGHT. A COLD FRONT APPROACHES AND MOVES ACROSS THE WATERS TOWARDS DAYBREAK THURSDAY...CAUSING WINDS TO SHIFT FROM THE NW. NORTH WINDS ARE FORECAST TO INCREASE TO ARND 20 KT FRI MORNING AS LOW PRES MOVES OFFSHORE. A SCA MAY BE NEEDED ON THE OCEAN WATERS FRI INTO FRI EVE FOR WINDS AND SEAS DUE TO A MODEST NLY FLOW WITH LOW PRES PASSING TO THE E. TRANQUIL CONDS THEN PREVAIL ON ALL WATERS THROUGH SUN. AN SCA MAY BE NEEDED AGAIN SUN NIGHT THROUGH MON ON AT LEAST THE OCEAN AS A COASTAL STORM PASSES WELL S AND E OF THE AREA. ALTHOUGH THERE IS SOME UNCERTAINTY WITH THE TRACK OF THIS STORM...SEAS SHOULD STILL BUILD TO AT LEAST 5 FT. HAVE LOWER CONFIDENCE IN THE WIND FORECAST.
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&& .HYDROLOGY... THURSDAY NIGHT-FRIDAY...1-2 INCHES OF SNOW LIKELY FOR LONG ISLAND AND SE CT. LOW CHC OF 3-6 INCH SNOW FOR THIS SAME AREA. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ350-353-355.
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&& $$

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