Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 012126 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 426 PM EST SUN MAR 1 2015 .SYNOPSIS...
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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.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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BAND OF FRONTOGENETICALLY FORCED MODERATE TO HEAVY SNOW ACROSS LONG ISLAND AND NYC METRO ATTM...WITH SNOWFALL RATES UP TO AN INCH PER HOUR. PER HRRR THIS BAND SHOULD SHIFT MORE INTO LONG ISLAND AND COASTAL CT OVER THE NEXT COUPLE OF HOURS...AND PERSIST THERE INTO AT LEAST THE FIRST PART OF THIS EVENING. HAVE BUMPED UP SNOWFALL TOTALS ESPECIALLY ACROSS SUFFOLK COUNTY AND AND COASTAL SE CT. GIVEN THIS PLUS A SPOTTER REPORT OF 2 INCHES ON THE GROUND IN WEST ISLIP...WILL ISSUE WINTER STORM WARNINGS FOR THOSE AREAS...WHERE 5-7 INCHES OF ACCUMULATION IS EXPECTED. ELSEWHERE EXPECT A SOLID ADVY EVENT...WITH 4-6 INCHES OF SNOW. A SPOTTER FROM BROOKLYN REPORTED SLEET MIXING IN WITH THE SNOW...WHICH CORRELATES WELL WITH RADAR DUAL-POL CC. THIS TRANSITION SHOULD BE BRIEF...AND EXPECT PRECIP TO TRANSITION BACK MORE TOWARD SNOW BEFORE A MORE DEFINITE TRANSITION LINE NOW EXTENDING FROM TTN-WRI-ACY MOVES IN. THIS SHOULD MAKE IT TO NYC METRO BY 00Z...THEN TO NEAR TEB-ISP BY LATE EVENING. AREAS SOUTH OF THAT LINE SHOULD SEE A GLAZE TO A TENTH OF AN INCH OF ICE THIS EVENING BEFORE PRECIP WINDS DOWN AFTER MIDNIGHT.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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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.
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&& .LONG TERM /TUESDAY THROUGH SATURDAY/...
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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.
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&& .AVIATION /20Z SUNDAY THROUGH FRIDAY/...
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WEAK LOW PRESSURE WILL TRACK TO THE SOUTH THEN EAST OF LONG ISLAND TONIGHT. HIGH PRESSURE BUILDS IN FROM THE WEST ON MONDAY. MAINLY LIFR TO VLIFR ACROSS THE AREA...WITH POCKETS OF IFR IN MAINLY MODERATE TO OCCASIONALLY HEAVY SNOW. SHOULD REMAIN ALL SNOW KSWF/KHPN/KBDR/KGON/KTEB. SNOW WILL CHANGE TO ZR AT KJFK AROUND 1Z AND CHANGE TO ZR AT KISP AROUND 2Z. FOR NOW HAVE KEPT CHANGE OVER AT KEWR AND KLGA TO ZR AT 3Z...BUT BEGINNING TO HAVE SOME DOUBTS THIS WILL OCCUR. PRECIPITATION WILL COME TO AN END A COUPLE OF HOURS ON EITHER SIDE OF MIDNIGHT FROM W TO E. MOST LIKELY TOTAL RUNWAY ACCUMULATIONS BY 06Z MON: KGON/KISP...4-7 INCHES. KSWF/KHPN/KBDR/KTEB/KLGA/KJFK/KEWR...4-6 INCHES. AFTER THE PRECIPITATION ENDS...CONDITIONS TRANSITION TO VFR BY AROUND 12Z. WINDS IN THE PROCESS OF BECOMING LIGHT AND VARIABLE THROUGHOUT. AS THE PRECIPITATION ENDS WINDS GO SW THEN W AT UNDER 10 KT EARLY MONDAY MORNING. WINDS THEN BECOME NW AND INCREASE TO 13-18G22-27KT BY AROUND MID MONDAY MORNING. .OUTLOOK FOR 18Z MONDAY THROUGH WEDNESDAY... .MONDAY AFTERNOON-TUESDAY MORNING...VFR. NW WINDS G25-30 KT LIKELY INTO EARLY MONDAY EVENING. .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.
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&& .MARINE...
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TRANQUIL TODAY WITH DEPARTING HI PRES...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.
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&& .HYDROLOGY...
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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.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR CTZ005>012. NY...WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR NYZ067>075- 078>081-176>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. && $$ SYNOPSIS...GOODMAN/24 NEAR TERM...GOODMAN SHORT TERM...GOODMAN LONG TERM...24 AVIATION...MALOIT MARINE...GOODMAN/24 HYDROLOGY...GOODMAN/24

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