Area Forecast Discussion
Issued by NWS Upton, NY

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102 FXUS61 KOKX 050546 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1246 AM EST FRI FEB 5 2016 .SYNOPSIS... WAVES OF LOW PRESSURE WILL DEVELOP ALONG A COLD FRONT AND PASS OFFSHORE TONIGHT AND FRIDAY. HIGH PRESSURE BUILDS IN FROM THE SOUTHWEST FRIDAY NIGHT INTO THE WEEKEND. FAIR WEATHER OVER THE WEEKEND WILL GIVE WAY TO A CHANCE FOR SNOW DURING THE BEGINNING OF NEXT WEEK. A COLD AIR MASS WILL THEN BRING TEMPERATURES TO BELOW NORMAL LEVELS FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH TODAY/...
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FORECAST IS ON TRACK. ALL NEAR TERM HI-RES GUIDANCE IS SIGNALING POTENTIAL FOR HIGHER SNOWFALL AMTS PER HIGHER QPF AND AS COLDER/DRIER AIR FILTERS DOWN INTO THE AREA ATTM...AS EVAPORATIVE COOLING OF FALLING PRECIP ALSO HELPS LOWER TEMPS FURTHER OVERNIGHT...AND AS SOME FAIRLY STRONG BANDING FEATURES PER 00Z NAM/RAP DEVELOP NEARBY LATE TONIGHT AND SWING ACROSS. HAVE INCREASED AMTS AT LEAST AN INCH...AND MORE EAST OF NYC. AMTS ACROSS SE CT AND MUCH OF CENTRAL/EASTERN LONG ISLAND SHOULD NOW FALL INTO THE 5-8 INCH RANGE...AND SO HAVE UPGRADED EXISTING ADVYS TO WINTER STORM WARNINGS THERE. THERE ARE STILL SOME UNCERTAINTIES. FIRST IT IS NOT TOTALLY OUT OF THE QUESTION THAT AMTS UP TO 6 INCHES COULD FALL A LITTLE FARTHER WEST INTO SW CT AND NASSAU COUNTY AS WELL. SECOND...IF COLDER AIR TAKES LONGER TO REACH THE FORKS OF LONG ISLAND AMTS COULD STILL BE HELD DOWN BELOW 6 INCHES THERE. FINALLY...A SHARP BACK EDGE TO THE PRECIP SHIELD MEANS THAT PARTS OF ORANGE COUNTY COULD STILL SEE LESS THAN AN INCH...BUT WITH HIGHER CONFIDENCE THAT THE SE PORTION COULD STILL SEE AT LEAST 2-3 INCHES...EXPANDED ADVYS TO THERE AND NEARBY WRN PASSAIC AS WELL. A COUPLE OF LOW PRESSURE WAVES PASS BY TO OUR SE ALONG A COLD FRONT TONIGHT AND FRIDAY. THE TWO WAVES WILL BRING PCPN TO MOST...IF NOT ALL OF THE CWA TONIGHT INTO FRI MORNING. THE SECOND WAVE WILL BE ENHANCED BY A STRONG SHORTWAVE BEGINNING TO SHIFT THROUGH AS WELL AS SYNOPTIC LIFT COURTESY OF THE RIGHT REAR QUADRANT OF AN UPPER JET STREAK. MODELS OVER THE PAST COUPLE OF DAYS HAVE TRENDED WEST WITH QPF OUTPUT. TEMPS STILL WEIGHTED MORE TOWARD COLDER NAM WHICH USUALLY DOES BETTER IN WINTERTIME PRECIP SITUATIONS. SKIES THEN BEGIN TO CLEAR OUT DURING FRIDAY AFTERNOON.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/... MOSTLY CLEAR WITH HIGH PRESSURE BUILDING IN. LOW TEMPS ARE A MAV/NAM MOS BLEND. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... A SFC HIPRES RIDGE EXTENDS NEWD INTO THE REGION SAT. DESPITE COLD TEMPS ALOFT WITH H85 AROUND -8C...SW FLOW THRU THE LAYER SHOULD ALLOW FOR DEEP MIXING BRINGING HI TEMPS AOA 40F. ON SUN...AN UPR LOW TRACKING ACROSS QUEBEC PROGGED TO DROP A CDFNT THRU DURING THE DAY. THE CAA APPEARS TOO LATE ATTM TO HAVE AND IMPACT ON HI TEMPS. ALTHOUGH THERE MAY BE SOME WEAK LIFT AND LIKELY TO BE SOME MID LVL MOISTURE WITH THE FRONT...THE SYS WILL BE BATTLING SUBSIDENCE. AS A RESULT...AGREED WITH THE MODEL CONSENSUS OF A DRY FROPA. A COUPLE OF QUESTIONS FOR THE BEGINNING OF NEXT WEEK. THE FIRST IS DEEP LOW PRES WHICH IS SPAWNED OFF THE SERN ATLC COAST AND TRACKS NEWD OVER THE OCEAN. THE GFS IS WAY OUT OF RANGE...WHILE THE ECMWF DESPITE A SLGT EWD TREND WITH THE 12Z RUN REMAINS CLOSE ENOUGH TO PERHAPS GRAZE THE TWIN FORKS. THIS STORM WILL NEED TO BE WATCHED BECAUSE THE MODEL DROPS IT INTO THE 970S. STILL...ONLY VERY LOW POPS FOR THIS STORM ATTM...WHICH ACTUALLY BLEEDS INTO THE NEXT SYS WHICH APPEARS MORE LIKELY TO IMPACT THE CWA. THIS ONE IS ROOTED IN A BROAD H5 LOW WHICH SPINS INTO THE NERN CONUS AND ALLOWS LOW PRES TO DEVELOP JUST OFFSHORE. BASED ON THE GEFS...A PROG CLOSER TO THE ECMWF APPEARS TO BE THE CONSENSUS ATTM. OR IN GFS TERMS...A LOW SLIGHTLY FURTHER S THAN THE OPERATIONAL 12Z RUN. POPS WERE INCREASED INTO THE 50 PERCENT RANGE FOR LATE MON THRU TUE. DID MAINTAIN SOME RAIN CHCS WITH THE SNOW IN CASE THE FURTHER NWD SOLN PANS OUT...BRINGING IN WARMER MARITIME AIR. THE CYCLONIC FLOW ALOFT COULD ALLOW FOR SOME RESIDUAL LGT SNOW ON WED...BUT CAPPED POPS AT 20 PERCENT DUE TO DOWNSLOPE FLOW COMPONENT. SUPERBLEND TEMPS THU APPEAR GOOD WITH A CHILLY PATTERN IN PLACE. AN ARCTIC SHOT POSSIBLE NEXT WEEKEND. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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PERIODS OF LIGHT RAIN WILL MIX WITH LIGHT SNOW BY 08Z OR SO BEFORE TRANSITIONING TO ALL SNOW BY AROUND 11Z. MVFR CONDS WILL LOWER TO IFR AT ONSET OF SNOW...AND LIFR CONDS EXPECTED IN PERIODS OF MODERATE TO HEAVY SNOW WITH CIGS LESS THAN 500 FT AND VSBYS LESS THAN 1 MILE IS LIKELY FROM AROUND 10-16Z. CONDS GRADUALLY LIFT TO VFR IN THE AFTERNOON AS THE SNOW DEPARTS. NE WINDS WILL BACK TO THE N AND WILL INCREASE TO AROUND 15 KT WITH GUSTS TO 25 KT...THEN NW WINDS WILL INCREASE FURTHER TO 15-20 KT WITH GUSTS UP TO 30 KT DURING THE AFTERNOON. TOTAL SNOW ACCUMULATIONS: NYC METRO TERMINALS...3-5 INCHES KISP/KGON...6-8 INCHES. KSWF...2-4 INCHES. .OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY... .FRIDAY NIGHT-SUNDAY...VFR. SW WINDS G15-20KT POSSIBLE DURING THE DAY ON SATURDAY. .MONDAY-TUESDAY...MAINLY VFR EARLY MONDAY. MVFR OR LOWER POSSIBLE LATE MONDAY-TUESDAY WITH CHANCE OF LIGHT SNOW.
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&& .MARINE... WINDS AND SEAS INCREASE WITH OFFSHORE LOW PRESSURE. SCA CONDS WILL INCREASE TO GALES ON THE OCEAN DURING FRIDAY. ELSEWHERE...HAVE GONE WITH SCA DURING THE DAY FRIDAY. RAFT LEVELS TODAY INTO TONIGHT. THEREFORE THE ADVISORY HAS BEEN EXTENDED THROUGH FRIDAY. SOME RESIDUAL SCA CONDITIONS ON THE OCEAN FOR EARLY FRIDAY NIGHT. OTHERWISE...CONDITIONS TREND TO BELOW SCA LATER ON FRIDAY NIGHT AND CONTINUING THROUGH THE WEEKEND WITH HIGH PRESSURE FROM THE SOUTHWEST BUILDING IN. CONDITIONS BECOME MORE ROUGH NEXT WEEK WITH THE POTENTIAL WAVES OF LOW PRESSURE. SCA WILL BE MORE PROBABLE IN THIS TIME FRAME. && .HYDROLOGY... TONIGHT INTO FRIDAY...LIQUID EQUIVALENT OF 1 TO 1.5 INCHES FCST FOR MUCH OF LONG ISLAND AND SE CT...0.5 TO 1 INCH FOR NYC METRO AND SW CT...AND 0.25 TO 0.5 INCHES NORTH/WEST. PCPN STARTS OUT AS RAIN...BUT SHOULD BE CHANGING TO SNOW FOR MOST SPOTS LATE TONIGHT INTO EARLY FRI MORNING. NO HYDROLOGIC IMPACTS EXPECTED. WIDESPREAD MEASURABLE PCPN POSSIBLE LATE MON THRU TUE. MOST OF THAT COULD BE IN THE FORM OF SNOW. && .OKX WATCHES/WARNINGS/ADVISORIES...
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CT...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR CTZ005-006- 009-010. WINTER STORM WARNING UNTIL 3 PM EST THIS AFTERNOON FOR CTZ007- 008-011-012. NY...WINTER STORM WARNING UNTIL 3 PM EST THIS AFTERNOON FOR NYZ078>081. WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ067. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NYZ068>075- 176>179. NJ...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR NJZ002. WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR NJZ004-006- 103>108. MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST THIS EVENING FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ350-353-355. GALE WARNING FROM 6 AM THIS MORNING TO 6 PM EST THIS EVENING FOR ANZ350-353-355.
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&& $$ SYNOPSIS...JMC/JC NEAR TERM...JC/GOODMAN SHORT TERM...JC LONG TERM...JMC AVIATION...MPS MARINE...JMC/JC/GOODMAN HYDROLOGY...JMC/JC/GOODMAN

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