Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 010911 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 411 AM EST SUN FEB 1 2015 .SYNOPSIS... A COLD FRONT MOVES ACROSS THE AREA TODAY AS HIGH PRESSURE BUILDS TO THE NORTH. LOW PRESSURE APPROACHES FROM THE OHIO VALLEY TONIGHT AND PASSES JUST SOUTH OF LONG ISLAND MONDAY. THE LOW TRACKS WELL TO THE EAST MONDAY NIGHT. HIGH PRESSURE BUILDS TO THE SOUTH AND EAST TUESDAY AND TUESDAY NIGHT. AN ARCTIC FRONT APPROACHES FROM THE NORTHWEST WEDNESDAY...THEN PUSHES THROUGH THE AREA WEDNESDAY NIGHT. CANADIAN HIGH PRESSURE BUILDS IN THURSDAY THROUGH FRIDAY...AS LOW PRESSURE TRACKS WELL TO THE SOUTHEAST. THIS HIGH BUILDS TO THE SOUTH FRIDAY NIGHT. A COLD FRONT APPROACHES FROM THE NORTH ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WEAK RIDGING ALOFT AHEAD OF UPSTREAM TROUGH CAN BE EXPECTED TODAY. MOISTURE INCREASES AHEAD OF AN AREA OF LOW PRESSURE AND LIFT ALONG THE FRONTAL BOUNDARY. SFC HIGH PRESSURE MOVES TO THE SOUTH...WITH ANOTHER AREA OF HIGH PRESSURE BUILDING NORTH OF THE GREAT LAKES REGION. IN BETWEEN...FRONTAL BOUNDARY PASSES THROUGH AND REMAINS TO THE SOUTH TODAY. CHILLY MORNING TEMPS WILL RISE TO AROUND OR INTO THE LOWER 30S TODAY PER MOS BLEND. MOST OF THE DAY WILL BE DRY...ALTHOUGH A FEW SNOW FLAKES MAY BE OBSERVED LATE FOR WESTERN SECTIONS AHEAD OF THE TROUGH AND IN RESPONSE TO WEAK LIFT IN WARM AIR ADVECTION. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... CHALLENGING WINTER FORECAST...WITH MIXED PRECIPITATION TYPE TO DEAL WITH THIS TIME FRAME. A SLIGHT NORTHWARD TREND TO THE SFC LOW TRACK IS NOTED. STRONG LIFT AHEAD OF TROUGH...WITH PLENTY OF MOISTURE TAPPED IN FROM THE SOUTH...WILL SET THE STAGE FOR A HEAVY PRECIP EVENT. ANALYSIS OF 00Z NWP SUITE INDICATES MID AND UPPER LEVEL TROUGH MOVES QUICKLY ACROSS THE MID SECTION OF THE COUNTRY THIS EVENING...TRACKING TOWARD THE EAST COAST BY MONDAY AFTERNOON. SURFACE LOW ALONG A FRONTAL BOUNDARY OVER THE OHIO VALLEY THIS EVENING MOVES EAST TRACKING ACROSS SRN PA TOWARD THE SRN OR CENTRAL NJ COAST EARLY MONDAY. THE LOW TRACKS JUST SOUTH MONDAY AFTERNOON. THE MID/UPPER LEVEL TROUGH MOVES THROUGH BY MONDAY EVENING...WITH SFC LOW TRACKING WELL TO THE EAST. VERY TOUGH FORECAST FOR MULTIPLE REASONS. MODELS DO INDICATE LOW LEVEL WARM AIR ADVECTION OCCURRING AS H8 LOW TRACKS OVER OR JUST NORTH OF NYC. AT THE SURFACE...WINDS REMAIN GENERALLY FROM THE EAST TONIGHT AHEAD OF THE LOW AND TO THE NORTH OF THE FRONTAL BOUNDARY. BY MONDAY...ENOUGH WARM AIR ALOFT MOVES IN...WITH NAM AND ECMWF FAIRLY CLOSE WITH REGARD TO TEMPS ALOFT. GFS IS SLIGHTLY WARMER. LOOKING AT SFC AND BOUNDARY LAYER...FOLLOWED A GRIDDED MOS...NAM DOWNSCALE BLEND FOR SLOW WARMING IN EAST FLOW...MAINLY FOR EASTERN LONG ISLAND AND POSSIBLY INTO PORTIONS OF SOUTHERN LONG ISLAND AND SRN PORTIONS OF NYC. INTERESTINGLY...HIGH RES ARW AND NMM TRACK THE LOW JUST SOUTH...BUT PROG THE COASTAL FRONT ACROSS LONG ISLAND...WHICH SETS UP A LARGE TEMPERATURE GRADIENT ON EITHER SIDE OF THE FRONT. TEMPS IN THE 40S AS WINDS TURN SOUTH. THIS OBVIOUSLY WOULD BE PROBLEMATIC AND WOULD REQUIRE A HUGE SHIFT IN THE FORECAST. AGAIN...WILL FOLLOW THE NAM/GFS/ECMWF IN KEEPING THE LOW AND CSTL FRONT JUST SOUTH...BUT WARMING EAST END OF LI AND SRN LI SUFFICIENTLY TO RESULT IN RAIN. ACROSS THE INTERIOR...ENOUGH WARM AIR ALOFT FOR SNOW MIXING WITH SLEET AND FREEZING RAIN...STRETCHING SW TO NE ACROSS THE AREA. GIVEN COLD WATER TEMPS...WOULD BELIEVE TEMPS DO NOT RISE MUCH ABOVE 32 FOR LONG ISLAND AND INTO NYC. WILL CONVERT THE WATCHES TO WARNINGS...EXCEPT EASTERN LONG ISLAND...SOUTHERN SUFFOLK AND SOUTHERN NASSAU. GIVEN THE HIGH LEVEL OF UNCERTAINTY...WILL ALLOW THE DAY SHIFT ONE MORE LOOK TO DETERMINE CONVERSION TO WARNINGS OR TO ADVISORIES. ANY FURTHER NORTH SHIFT TO SFC LOW AND H8 LOW WOULD RESULT IN MORE LIQUID. IN ADDITION...FREEZING RAIN A CONCERN FOR A GOOD PORTION OF THE AREA. THE BOTTOM LINE IS...HIGH IMPACT FOR MORNING COMMUTE WARRANTS A WARNING FOR MOST OF THE AREA. CLOSER TO THE COAST...SNOW TO RAIN/FZRA/IP. THEN BACK TO SNOW BEFORE ENDING AS DEFORMATION BAND MOVES THROUGH ON THE BACK SIDE AS THE LOW DEPARTS LATE IN THE DAY MONDAY. INTERIOR...MAINLY SNOW...WITH POSSIBLY SOME SLEET MONDAY MORNING. EASTERN/SRN LONG ISLAND...SNOW TO RAIN OR FREEZING RAIN (DEPENDING ON THOSE SFC TEMPS)...THEN POSSIBLY BACK TO SNOW. ***IT IS IMPORTANT TO NOTE THAT MANY COASTAL AREA SNOW TOTAL FORECASTS ARE FOR SNOW AHEAD OF WINTRY MIX TRANSITION...AND AFTER WINTRY MIX CHANGES BACK TO SNOW. HOWEVER...ANY RAIN WILL LIKELY WASH THE SNOW AWAY...LEAVING SLUSHY CONDITIONS AND LOWER TOTALS AS A RESULT*** SO...MORNING COMMUTE WILL LIKELY BE A MESS ALL CWA. THE AFTERNOON COMMUTE WILL LIKELY BE PROBLEMATIC AS WELL FOR MUCH OF THE AREA. ANY LEFTOVER SLUSH WILL FREEZE AS ARCTIC AIR RUSHES BACK IN. EXPECT ICY CONDITIONS LATE IN THE DAY...ESPECIALLY FOR AREAS THAT CHANGE TO RAIN LATE MORNING/EARLY AFTERNOON. HEAVIEST PRECIP IS LATE TONIGHT (09-11Z THROUGH 16-18Z) WHEN GREATEST LIFT IS REALIZED. ANY LINGERING LIGHT SNOW MONDAY EVENING ENDS AS THE TROUGH MOVES EAST/ GUSTY NORTHERLY FLOW WILL USHER IN VERY COLD AIR. LOW TEMPS IN THE SINGLE DIGITS TO THE TEENS. && .LONG TERM /TUESDAY THROUGH SATURDAY/... ZONAL FLOW ALOFT SHOULD KEEP THINGS DRY TUESDAY AND TUESDAY NIGHT. A WEAK SHORTWAVE PASSES ON WEDNESDAY...WITH A STRONGER SHORTWAVE APPROACHING WEDNESDAY NIGHT...JUST BEHIND AN ARCTIC COLD FRONT AT THE SURFACE. THERE SHOULD BE ENOUGH FORCING WITH THE SHORTWAVES AND THE FRONT TO PRODUCE ISOLD-SCT -SHSN WEDNESDAY AND WEDNESDAY NIGHT. THERE REMAIN MODEL DIFFERENCES FROM THURSDAY ON. BOTH THE ECMWF AND CMC SUGGEST THAT THE ARCTIC FRONT BECOME AN ANAFRONT WITH SNOW BEHIND THE FRONT THURSDAY-THURSDAY NIGHT...AND THE CMC GOES FARTHER AND BRINGS A COASTAL LOW ALONG IT CLOSE ENOUGH TO IMPACT THE AREA. THE GFS GENERALLY KEEP THINGS DRY THURSDAY/THURSDAY NIGHT. FOR NOW WENT WITH CHANCE POPS ON THURSDAY...EXCEPT SLIGHT CHANCE FAR N TIER...THEN SLIGHT CHANCE POPS THURSDAY NIGHT...EXCEPT DRY FAR NNW TIER OF THE CWA. ALL MODELS AGREE SHOULD BE DRY FRIDAY-SATURDAY ON NW FLOW ALOFT. MAIN STORY OF THE EXTENDED WILL BE BITTERLY COLD AIR ARRIVING WEDNESDAY NIGHT AND LASTING THROUGH FRIDAY NIGHT. HIGHS WILL STRUGGLE TO REACH THE UPPER TEENS TO LOWER 20S AND LOWS WILL GENERALLY BE IN THE SINGLE DIGITS THURSDAY AND FRIDAY NIGHT. WIND CHILLS SHOULD BE BELOW ZERO THURSDAY NIGHT/FRIDAY MORNING...AND POSSIBLY BE NEAR ADVISORY CRITERIA OVER NW INTERIOR ZONES. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... **HIGH IMPACT EVENT TONIGHT THROUGH MONDAY** HIGH PRESSURE OVER THE TERMINALS WEAKENS EARLY THIS MORNING AS A WARM FRONT AND ASSOCIATED LOW PRESSURE APPROACH. THE WARM FRONT WILL BE IN THE VICINITY BY 00Z MONDAY. LIGHT SNOW COULD BE DEVELOPING BY LATE IN THE AFTERNOON...HOWEVER...STEADY SNOW IS EXPECTED 00Z TO 02Z MONDAY ACROSS THE NYC AREA TERMINALS WITH CONDITIONS LOWERING TO IFR. THE SNOW SPREADS EAST...REACHING EASTERN LONG ISLAND AND KGON AROUND 04Z. WEST TO NORTHWEST WIND UNDER 10 KT...WILL BACK TO SOUTHWEST AND SOUTH DURING SUNDAY...BECOMING EAST SOUTHEAST SUNDAY EVENING...AND INCREASING TO 10 KT TO 15 KT. .OUTLOOK FOR 09Z MONDAY THROUGH THURSDAY... .LATE TONIGHT-MONDAY...IFR CONDITIONS IN SNOW. A WINTRY MIX OF SLEET...SNOW AND FREEZING RAIN BECOMES LIKELY EARLY MONDAY MORNING AT THE NYC METRO TERMINALS AND ACROSS LONG ISLAND. THE WINTRY MIX PUSHES FARTHER NORTH DURING MONDAY MORNING AND CONTINUES INTO THE AFTERNOON BEFORE GOING BACK TO ALL SNOW BEFORE ENDING MONDAY EVENING. .MONDAY NIGHT...BECOMING VFR AS SNOW COMES TO AN END. N-NW WIND 15 TO 20 KT WITH GUSTS UP TO 30 KT. .TUESDAY...VFR. .WEDNESDAY...VFR. A CHANCE OF SNOW SHOWERS WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT WITH LOCALLY MVFR TO IFR CONDITIONS. .THURSDAY...VFR. NW GUSTS 20 KT. && .MARINE... WINDS AND SEAS HAVE FALLEN BELOW SCA LEVELS ON THE COASTAL OCEAN WATERS...SO THE SCA THAT WAS IN EFFECT THROUGH 6AM THIS MORNING THERE HAS BEEN CANCELLED. THE REGION WILL BE UNDER A RELATIVELY RELAXED PRESSURE GRADIENT THROUGH THIS EVENING...SO SUB-SMALL CRAFT CONDITIONS ARE EXPECTED. WINDS INCREASE TO SMALL CRAFT LEVELS ON ALL WATERS AFTER MIDNIGHT AND PERSIST THROUGH MONDAY...SO A SMALL CRAFT ADVISORY HAS BEEN HOISTED ACCORDINGLY. GUSTS TO GALE FORCE ARE PROBABLE MONDAY NIGHT ON THE COASTAL OCEAN WATERS...SO A GALE WATCH HAS BEEN ISSUED THEN FOR THOSE WATERS. FOR THE NON-OCEAN WATERS...SMALL CRAFT CONDITIONS ARE EXPECTED TO CONTINUE...SO THE SMALL CRAFT ADVISORY FOR THESE WATERS LAST THROUGH THEN. THERE IS A SMALL CHANCE FOR GALE FORCE WIND GUSTS ON THE NON-OCEAN WATERS AS WELL MONDAY NIGHT. SMALL CRAFT CONDITIONS WILL LIKELY CONTINUE ON ALL WATERS TUESDAY...AND POSSIBLY GALE FORCE WINDS GUSTS IN THE MORNING ON THE COASTAL OCEAN WATERS. CONFIDENCE IN THIS IS NOT QUITE HIGH ENOUGH FOR ANY HEADLINES ON TUESDAY YET. SUB-SMALL CRAFT CONDITIONS ARE EXPECTED ON THE NON-OCEAN WATERS TUESDAY NIGHT-THURSDAY WITH WINDS 15 KT OR LESS. ON THE OCEAN WATERS SMALL CRAFT LEVEL SEAS ARE POSSIBLE THROUGH THE TIME FRAME...WITH THE BEST CHANCE WEDNESDAY-THURSDAY THOUGH A COMBINATION OF WINDS JUST UNDER SMALL CRAFT LEVELS AND SWELLS. && .HYDROLOGY... GENERALLY 1 TO 1 1/2 INCHES OF LIQUID FORECAST WITH THE SYSTEM TONIGHT THROUGH MONDAY. MOST OF THIS WILL BE SNOW AND SLEET ACROSS NE NJ...LOWER HUDSON VALLEY AND CT. ACROSS LI/NYC THERE IS A POTENTIAL FOR A PERIOD OF HEAVY RAIN. AS SUCH...URBAN FLOODING ISSUES ARE POSSIBLE...ESPECIALLY DUE TO CLOGGED SNOW COVERED DRAINS. NO SIGNIFICANT WIDESPREAD PCPN IS FORECAST FOR THE REMAINDER OF THE PERIOD. && .TIDES/COASTAL FLOODING... AT THIS TIME IT APPEARS THAT FOR THE HIGH TIDE ON MONDAY...THAT DEPARTURES WILL REMAIN 1 TO 1.5 FEET BELOW THAT REQUIRED FOR COASTAL FLOODING. WITH DEPARTURES OF 1.5-2 FT REQUIRED AND ONLY .5 TO 1 FT DEPARTURES CURRENTLY FORECAST. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 6 PM EST MONDAY FOR CTZ005>012. NY...WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR NYZ079>081-179. WINTER STORM WARNING FROM 7 PM THIS EVENING TO 6 PM EST MONDAY FOR NYZ067>075-078-176>178. NJ...WINTER STORM WARNING FROM 7 PM THIS EVENING TO 6 PM EST MONDAY FOR NJZ002-004-006-103>108. MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST TUESDAY FOR ANZ330-335-338-340-345. GALE WATCH FROM MONDAY EVENING THROUGH LATE MONDAY NIGHT FOR ANZ350-353-355. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST MONDAY FOR ANZ350-353-355. && $$ SYNOPSIS...MALOIT/PW NEAR TERM...PW SHORT TERM...PW LONG TERM...MALOIT AVIATION...MPS MARINE...MALOIT HYDROLOGY...MALOIT/PW TIDES/COASTAL FLOODING...MALOIT

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