Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 020016 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 716 PM EST SUN MAR 1 2015 .SYNOPSIS... A FRONTAL SYSTEM WILL APPROACH FROM THE WEST...THEN PASS THROUGH TONIGHT AS WEAK LOW PRESSURE DEVELOPS SOUTH OF LONG ISLAND. HIGH PRESSURE WILL BRIEFLY BUILD IN MONDAY INTO MONDAY NIGHT... THEN PASS TO THE EAST ON TUESDAY. LOW PRESSURE WILL TRACK WELL NORTH OF THE AREA TUESDAY NIGHT AND WEDNESDAY...WITH A WARM FRONT LIFTING INTO THE AREA TUESDAY NIGHT...FOLLOWED BY A COLD FRONT WEDNESDAY AND A REINFORCING COLD FRONT WEDNESDAY NIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A BAND OF MODERATE SNOW ACROSS THE SOUTH SHORE OF LONG ISLAND AS OF 00Z...ALTHOUGH THINK SOME OF THIS IS A MIX OF SNOW...SLEET AND/OR FREEZING RAIN. LOWER CORRELATION COEFFICIENT VALUES STILL REMAIN JUST S OF LONG ISLAND...BUT EXPECT THEM TO COME ONSHORE SHORTLY. WHERE IT IS STILL ALL SNOW TOWARDS THE CENTRAL PART OF WESTERN SUFFOLK COUNTY...SNOWFALL RATES UP TO AN INCH PER HOUR ARE LIKELY OCCURRING...HOWEVER...THE HIGHER REFLECTIVITIES WILL PUSH TO THE EAST BY 01Z. SNOW TOTALS FORECAST STILL LOOKS ON TRACK WITH PERHAPS THE EXCEPTION OF SOUTHERN NASSAU COUNTY. HAVE BUMPED UP TOTALS A BIT THERE...AND COULD SEE SOME LOCATIONS IN EXTREME SOUTHERN PARTS OF THE COUNTY END WITH AROUND 6 INCHES...BUT HAVE MAINTAINED THE ADVSY. SOUTHERN PORTIONS OF NYC INTO SE METRO NJ ARE A MIX OF SNOW...SLEET AND/OR FREEZING RAIN. TOUGH CALL HOW FAR NORTH THE TRANSITION ZONE WILL GET BEFORE PCPN ENDS...BUT RECEIVED A REPORT AS FAR N AS EAST RUTHERFORD OF MIXED PCPN. REGIONAL RADAR IMAGERY INDICATES LIGHTER RETURNS ALREADY INTO THE LOWER HUDSON VALLEY AND NE NJ...SO ACCUMULATING SNOW HAS GENERALLY ENDED HERE. AREAS IN AND S OF THE TRANSITION ZONE SHOULD SEE A GLAZE TO A TENTH OF AN INCH OF ICE BEFORE PCPN WINDS DOWN AROUND MIDNIGHT OR SO. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... HIGH PRESSURE APPROACHES FROM THE WEST ON MONDAY...THEN BUILDS OVERHEAD ON TUESDAY. HIGHS ON MON WILL BE IN THE MID AND UPPER 30S...WITH A BRISK NW WINDS GUSTING TO 25-35 MPH. MUCH COLDER AIR WILL FOLLOW FOR MON NIGHT...AND UNDERCUT MOS GUIDANCE BY 2-3 DEG GIVEN DIMINISHING WINDS LATE AT NIGHT AND FRESH SNOW COVER...WITH LOWS IN THE TEENS FOR NYC METRO AND LONG ISLAND...AND SINGLE DIGITS FARTHER NORTH/WEST. && .LONG TERM /TUESDAY THROUGH SUNDAY/... MODELS ARE IN DECENT AGREEMENT AT H5 THROUGH THE WEEK...ALTHOUGH SLIGHT DIFFERENCES IN HEIGHTS BEGIN TO TAKE SHAPE DURING THE LATTER HALF FROM A DIGGING TROF IN THE MIDDLE OF THE COUNTRY. RIDGING AT THE SFC AND ALOFT TRACKS MOVES OFFSHORE ON TUE. PCPN WILL OVERSPREAD THE AREA LATE TUE AFTN AS SNOW...BUT WITH INCREASING S-SW WINDS AND STRONG WAA TEMPS WILL WARM TUE EVE/NIGHT WITH SNOW CHANGING TO MIXED PCPN THEN RAIN FROM S TO N. WARM FRONT LIFTS TOWARDS THE AREA TUE NIGHT...BUT THERE IS SOME UNCERTAINTY IF THE LLJ WILL BE STRONG ENOUGH TO PUSH IT THROUGH AT THE SFC. CLIMATOLOGY SAYS NO WITH THE LOW SO FAR TO THE NW AND VERY COLD WATERS/ICE...SO HAVE GONE BELOW GUIDANCE WITH HIGHS WED...GENERALLY LOWER 40S WITH MID 40S POSSIBLE IN NYC METRO. THE COMBINATION OF THESE TEMPS AND RAINFALL WILL RESULT IN MELTING SNOWPACK WHICH COULD LEAD TO MINOR FLOODING ACROSS THE AREA ON WED. COLD FRONT MOVES ACROSS WED FOLLOWED BY A REINFORCING COLD FRONT WED NIGHT. THE NORTHERN EDGE OF THE PCPN SHIELD OF A SOUTHERN STREAM SYSTEM RIDING ALONG THIS SECONDARY BOUNDARY COULD KEEP PCPN LINGERING WED NIGHT INTO THU. MODELS REMAIN SPLIT ON THIS...GFS IS FURTHER SUPPRESSED THAN EC SO HAVE KEPT CHC POPS. COLD AIR FILTERS IN BEHIND THE INITIAL COLD FRONT ON WED. THERMAL PROFILES SUPPORT A CHANGE BACK OVER TO SNOW WED NIGHT AND THU WITH ANY PCPN ASSOCIATED WITH THE SOUTHERN STREAM SYSTEM. ANOTHER SHOT OF ARCTIC AIR INFILTRATES THE AREA THU INTO FRI. STRONG CANADIAN HIGH PRES THEN BUILDS TOWARDS THE AREA INTO THE WEEKEND WITH DRY WEATHER. TEMPS WILL REBOUND AROUND 5 DEGREES BELOW NORMAL NEXT WEEKEND WITH WAA DEVELOPING. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... A FRONTAL SYSTEM WILL PASS THROUGH TONIGHT AS WEAK LOW PRESSURE DEVELOPS SOUTH OF LONG ISLAND. HIGH PRESSURE BUILDS MONDAY. A WINTRY MIX OF FREEZING RAIN...SNOW AND SLEET APPEARS TO BE LIGHTENING FROM WEST TO EAST FOR NYC METRO AND LI TERMINALS. ELSEWHERE...MAINLY SNOW IS EXPECTED. EXPECT STEADY PRECIP TO WIND DOWN BY 2-4Z. AFTER MIDNIGHT...PRECIP SHOULD END ALTOGETHER...EXCEPT A LITTLE LONGER AT KISP AND KGON. EVEN THOUGH PRECIP ENDS...LOW END MVFR OR IFR CEILINGS SHOULD LINGER OVERNIGHT. RETURN TO VFR MONDAY AFTER 11-13Z. WINDS WILL BE LIGHT AND VARIABLE...THEN WILL TURN TO THE WEST 5 TO 10 KTS AFTER MIDNIGHT. WINDS BECOME WEST/NORTHWEST AFTER 12Z...10 TO 15 KTS. BY 15Z...FREQUENT GUSTS 20 TO 30 KTS ARE EXPECTED. WINDS SHOULD REMAIN TO THE LEFT OF 310 MAG FOR THE MOST PART MONDAY...BUT WILL BE CLOSE. ADDITIONAL LIGHT SNOW ACCUMS ARE EXPECTED. MOST LIKELY TOTAL RUNWAY ACCUMULATIONS: KGON/KISP...4-7 INCHES. KSWF/KHPN/KBDR/KTEB/KLGA/KJFK/KEWR...3-6 INCHES. .OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT-TUESDAY MORNING...VFR. .TUESDAY AFTERNOON...CHANCE MVFR OR LOWER IN SNOW. .TUESDAY NIGHT...IFR OR LOWER LIKELY. SNOW...CHANGING TO A WINTRY MIX AFTER MIDNIGHT...AND THEN RAIN LATE AT ALL TERMINALS EXCEPT KSWF AND POSSIBLY CT TERMINALS. LLWS LIKELY. .WEDNESDAY...IFR OR LOWER POSSIBLE IN ANY RAIN - WITH A BRIEF PERIOD OF ZR POSSIBLE IN THE MORNING AT KSWF. LLWS POSSIBLE IN THE MORNING. .WEDNESDAY NIGHT-THURSDAY...MVFR OR LOWER POSSIBLE IN ANY PRECIPITATION...OTHERWISE VFR. IF THERE IS PRECIPITATION...SHOULD CHANGE TO ALL SNOW WEDNESDAY NIGHT AND POSSIBLY CONTINUE INTO THURSDAY. NW WINDS G15-20KT POSSIBLE. .THURSDAY NIGHT-FRIDAY...VFR. NW WINDS G15-20KT POSSIBLE THURSDAY NIGHT. && .MARINE... TRANQUIL TONIGHT...THEN WINDS INCREASE TO SCA LEVELS MON AND GRADUALLY DIMINISH MON NIGHT. EXPECT SUB-ADVY CONDS ON TUE AS HIGH PRES BUILDS ACROSS. SCA CONDS POSSIBLE ON THE OCEAN TUE NIGHT INTO THU BEHIND THE PASSAGE OF TWO COLD FRONTS...WITH A TIGHT PRES GRADIENT. SUB-ADVY CONDS THEN EXPECTED THEREAFTER AS THE PRES GRADIENT WEAKENS WITH ANOTHER BUILDING HIGH. && .HYDROLOGY... LIQUID EQUIVALENT QPF OF 4-6 TENTHS OF AN INCH EXPECTED TONIGHT. WITH ALL OF THIS EXPECTED TO BE EITHER FROZEN OR FREEZING PRECIPITATION...NO IMMEDIATE HYDROLOGIC IMPACT EXPECTED. BETWEEN 1/2 TO 1 INCH OF LIQUID EQUIVALENT PCPN IS POSSIBLE LATE TUE THROUGH WED. SOME OF THIS WILL FALL AS RAIN...THEREFORE THE COMBINATION OF THIS AND MELTING SNOW PACK COULD CAUSE MINOR FLOODING ISSUES. ICE WILL CONTINUE TO DEVELOP ON LOCAL AREA RIVERS AND STREAMS AS TEMPERATURES REMAIN WELL BELOW AVERAGE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR CTZ008-010>012. WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR CTZ005>007- 009. NY...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR NYZ078>081. WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR NYZ067>075- 176>179. NJ...WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR NJZ002-004- 006-103>108. MARINE...SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO MIDNIGHT EST MONDAY NIGHT FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY FROM 6 AM MONDAY TO 6 AM EST TUESDAY FOR ANZ350-353-355. && $$

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