Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 242145 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 445 PM EST SAT JAN 24 2015 .SYNOPSIS... RAPIDLY DEEPENING LOW PRESSURE WILL TRACK TO CAPE COD THIS EVENING AND THEN UP INTO THE CANADIAN MARITIMES ON SUNDAY. A COLD FRONT WILL MOVE ACROSS THE AREA ON SUNDAY. HIGH PRESSURE BUILDS NORTH OF THE AREA SUNDAY NIGHT. STRONG LOW PRESSURE THEN APPROACHES MONDAY AND PASSES SOUTHEAST OF THE REGION MONDAY NIGHT INTO TUESDAY BEFORE CONTINUING NORTHEAST TUESDAY NIGHT AND WEDNESDAY. A WEAKER SYSTEM THEN PASSES THROUGH THURSDAY NIGHT INTO FRIDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... ***BRIEF SNOW BAND LI/CT EARLY...THEN BLACK ICE DEVELOPING TONIGHT*** LOW PRESSURE...SE OF MONTAUK POINT...WILL CONTINUE TO RAPIDLY INTENSIFY AS IT TRACKS TO E OF CAPE COD THIS EVENING. IN RESPONSE TO APPROACHING NORTHERN AND THEN SOUTHERN STREAM ENERGY...OPERATIONAL AND HIGH RES MODELS STILL SIGNALING A DEFORMATION BAND OF PRECIP DEVELOPING OVER THE REGION BETWEEN 19Z AND 21Z...AND SLOWLY TRANSLATING EAST THROUGH EARLY EVENING. AN ADDITIONAL 1 TO 3 TENTHS OF QPF POSSIBLE WITH THIS BAND...MAINLY EAST OF THE HUDSON...AND HIGHEST AMOUNTS ACROSS SE CT/E LI. THERMAL PROFILES AND DYNAMIC COOLING WILL BE ENOUGH TO TRANSITION ANY LIGHT WINTRY MIX TO SNOW ACROSS THE REGION. SNOW COULD BE BRIEFLY MODERATE TO HEAVY WITH THIS BAND ACROSS LI/CT. SO AN ADDITIONAL COATING TO 1 INCH OF SNOW POSSIBLE FOR NYC METRO AND EASTERN LOWER HUDSON VALLEY. COATING TO 2 INCH POTENTIAL ACROSS LI/CT. A WORST CASE OF AN ADDITIONAL 2 TO 4 INCHES ACROSS SOUTHERN CT. LOW PROB FOR THIS WORST CASE THREAT TO EXTEND DOWN TO LI. THE SNOW BAND WILL MOVE EAST FROM W TO E LATE THIS AFTERNOON INTO EARLY EVENING. ADVISORIES HAVE BEEN DROPPED WEST OF THE HUDSON BASED ON ABOVE...AND MAY BE ABLE TO DROP NYC/EASTERN HUDSON AT 4 PM BASED ON BANDING DEVELOPMENT. ADVISORIES FARTHER EAST WILL LIKELY BE EXTENDED TILL 00Z. TEMPS WILL STAY NEARLY STEADY OF SLOWLY RISE INTO THE LOWER AND MID 30S TODAY. SNOW ENDS AFTER 00Z ACROSS FAR EASTERN LI/SE CT...WITH BREEZY CONDITIONS AND TEMPS FALLING INTO THE LOWER TO MID 20S INLAND....AND UPPER 20S TO LOWER 30S CITY/COAST. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... SHORT WAVE TROUGH PASSES THROUGH NORTHERN NEW ENGLAND ON SUNDAY...WITH WEAKENING POLAR FRONT APPROACHING SUNDAY MORNING. FRONTAL PASSAGE LOOKS DRY...WITH JUST SOME SCT STRATO-CU. BREEZY AND MOSTLY SUNNY WITH HIGHS SUNDAY TOPPING OUT IN THE MID TO UPPER 30S. UPPER TROUGH SLIDES EAST SUN NIGHT WITH POLAR HIGH SLIDING INTO NEW ENGLAND. THIS SHOULD ALLOW FOR GOOD RADIATIONAL COOLING CONDS FIRST HALF OF SUNDAY EVENING WITH POTENTIAL FOR TEMPS TO DROP INTO THE TEENS INTERIOR AND PINE BARRENS AND LOWER 20S NYC METRO. COULD GET INTO SINGLE DIGITS ACROSS THE INTERIOR VALLEYS IF CLOUDS HOLD OFF LONG ENOUGH. THEREAFTER...ALL EYES ON STRONG SHORTWAVE ENERGY DIVING THROUGH THE CENTRAL PLAINS SUN AND INTO THE SE US SUN NIGHT. THIS WILL HAVE LOW PRESSURE BEGINNING TO TAKE SHAPE ACROSS THE SE US...WITH POTENTIAL FOR SOME LIGHT SNOW TO DEVELOP LATE SUN NIGHT INTO MONDAY MORNING ACROSS AT LEAST SOUTHERN AND WESTERN PORTIONS OF THE TRI-STATE. && .LONG TERM /MONDAY THROUGH SATURDAY/...
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MODELS ARE TRENDING FARTHER NW REGARDING A STORM THAT IS PROGGED TO EMERGE OFF THE CAROLINA COAST DURING MONDAY. AS THE STORM HEADS TO THE NORTH...AN ASSOCIATED UPPER TROUGH BECOMES STRONGLY NEGATIVELY TILTED BEFORE A 500 MB LOW CLOSES SOUTH OF US AT SOME POINT LATE MONDAY NIGHT INTO TUESDAY. THIS WOULD DRAW THE STORM CLOSER TOWARDS IT...EFFECTIVELY SLOWING DOWN ITS PROGRESS TO THE NE IN SPITE OF A BLOCKING LOW OVER THE CANADIAN MARITIMES MOVING AWAY. HEAVY SNOW AND STRONG WINDS ARE BECOMING INCREASINGLY LIKELY FOR AT LEAST EASTERN PORTIONS OF THE CWA. WITH THE UPPER LOW CLOSING OFF AND DEEPENING OF THE STORM...MESOSCALE BANDING BECOMES MORE LIKELY AS WELL...BUT IT IS VERY DIFFICULT TO SAY THIS FAR OUT IN ADVANCE WHERE IT WOULD SET UP. BUT BASED THE MID LEVEL FRONTOGENESIS AND DEFORMATION THAT MODELS ARE SHOWING...BANDED PCPN WOULD MOVE AT LEAST IN THE VICINITY OF THE CWA...PERHAPS LATE MONDAY NIGHT INTO TUESDAY MORNING. PCPN TYPE LOOKS LIKE TO BE ALL SNOW. RIGHT NOW ONLY A SLIGHT CHANCE THAT WARM AIR GETS WRAPPED INTO THIS SYSTEM AND CAUSES MIXED PCPN TYPES FOR EASTERN SECTIONS. SHOULD MODELS CONTINUE THE NW TREND OF THE STORM`S TRACK...PCPN TYPE ISSUES COULD BE A BIGGER CONCERN. WHAT IS MORE CERTAIN IS THAT A COLD AIR MASS WILL ALREADY BE IN PLACE WITH HIGH PRESSURE SHIFTING THROUGH SE CANADA MONDAY INTO TUESDAY...PROMOTING PCPN TYPE OF SNOW. DID NOT WANT TO TREND UPWARD TOO MUCH REGARDING POPS AND TOO HIGH WITH QPF/SNOW TOTALS AT THIS POINT AS LIKELY POPS ARE NOT CURRENTLY FORECAST UNTIL THE 5TH PERIOD...BUT WENT FAIRLY CLOSE TO RFC AND WPC GUIDANCE...WHICH SEEMS LIKE A GOOD COMPROMISE FROM THE HIGH QPF OUTPUT FROM ECMWF AND NAM...AND THE OTHER MODELS THAT DO NOT SHOW AS MUCH. BUT BASED ON THE NW TREND OF THE STORM...DID MAKE SOME UPWARD ADJUSTMENTS MAINLY WEST OF EASTERN LONG ISLAND AND SE CT. FORECAST WINDS DURING THIS STORM COULD BE ON THE CONSERVATIVE SIDE AS WELL...BUT FOR NOW...THINKING IS THAT EASTERN AND OTHER COASTAL SECTIONS HAVE A DECENT CHANCE OF SEEING GUSTS OVER 40 MPH. TOO EARLY FOR ANY HEADLINES REGARDING THE SNOW AND WIND POTENTIAL...BUT WILL ADDRESS AT LEAST THE SNOW ASPECT IN THE HWO AS WARNING CRITERIA SNOWFALL FOR AT LEAST SOMEWHERE IN THE CWA IS INCREASING IN LIKELIHOOD. BEHIND THE STORM...DRY WEATHER WEDNESDAY AND THURSDAY...THEN A WEAKER LOW AFFECTS US THURSDAY NIGHT INTO FRIDAY. CAPPED POPS A CHANCE FOR SNOW...WITH PCPN MORE LIKELY TO BE SNOW...BUT MIXED PCPN NOT OUT OF THE QUESTION.
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&& .AVIATION /22Z SATURDAY THROUGH THURSDAY/...
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HIGH IMPACT SNOW AND WIND EVENT POSSIBLE LATE MON NIGHT INTO TUE NIGHT...SEE OUTLOOK FOR DETAILS... LOW PRESSURE SOUTH OF NANTUCKET WILL CONTINUE TO RAPIDLY DEEPEN AND HEAD NORTHEAST...MOVING AWAY FROM THE AREA THIS EVENING. LIGHT PRECIP WITH IFR CONDS PERSIST OUT EAST...WHILE CONDS HAVE IMPROVED TO MVFR AT THE NYC METRO TERMINALS. HI-RES MODELS FORECAST A NARROW BAND OF LIGHT SNOW OR SNOW/RAIN MIX TO DEVELOP OVER THE AREA FROM 20Z-22Z AND MOVE EAST INTO THIS EVENING...THAT COULD BRING IFR CONDS AS LEAVE A COATING OF ACCUMULATION ON RUNWAYS. AFTER THIS PASSES...EXPECT RAPID IMPROVEMENT TO VFR...IN NYC METRO AROUND 00Z-01Z...AND AN HR OR TWO LATER FARTHER EAST. WINDS IN NYC METRO AREA ALREADY BEGINNING TO BACK/SHIFT NW...AND SHOULD DO SO ELSEWHERE THIS EVENING. AFTER PRECIP ENDS...WINDS SHOULD SHIFTING WNW ON OR JUST LEFT OF 300 TRUE...AND INCREASE TO 10-15 KT WITH GUSTS EITHER SIDE OF 20 KT. THESE WINDS SHOULD DIMINISH TO JUST UNDER 10 KT AFTER MIDNIGHT... THEN RAMP UP AGAIN BY 13Z-14Z SUNDAY. .OUTLOOK FOR 18Z SUNDAY THROUGH THU... .SUNDAY AFTERNOON...VFR. W WINDS 10-15 KT WITH GUSTS 15-20 KT...DIMINISHING LATE. .SUNDAY NIGHT...VFR. .MON-MON EVENING...MVFR CONDS POSSIBLE IN LIGHT SNOW. E-NE WINDS 10-15 KT WITH GUSTS 20-25 KT. .MON NIGHT-TUE NIGHT...IFR/LIFR CONDS IN SNOW. POTENTIAL FOR HEAVY SNOW WITH NE-N WINDS G35-45 KT...ESPECIALLY LATE MON NIGHT INTO TUE AFTERNOON. .WED...VFR. NW WINDS G25-30KT. .THU...VFR.
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&& .MARINE... MARGINAL SCA CONDITIONS WILL PERSIST ACROSS MOST WATERS THROUGH SUN AFT...WITH HIGHEST LIKELIHOOD THIS EVENING INTO SUNDAY MORNING. MARGINAL GALE GUSTS STILL LIKELY ACROSS THE OCEAN WATERS BETWEEN MORICHES INLET AND MONTAUK POINT THIS EVENING. SEAS 7 TO 10 FT ONT HE OCEAN WATERS. NLY WINDS BECOME NW TONIGHT AND THEN WEST ON SUN AS DEEPENING LOW PRESSURE LIFTS NE INTO FROM JUST EAST OF NEW ENGLAND THIS EVE TO THE CANADIAN MARITIMES ON SUN. WINDS EXPECTED TO GRADUALLY FALL BELOW SCA SUN AFT INTO EVE...AND SEAS SUN NIGHT. WINDS INCREASE MONDAY THROUGH TUESDAY WITH A STRONG STORM FORECAST TO PASS TO THE SOUTHEAST. WILL PROBABLY NEED A GALE WATCH...AND BASED ON MODEL TRENDS...STORM FORCE WINDS ARE NOT OUT OF THE QUESTION. WILL ADDRESS GALE POTENTIAL IN THE HWO. WINDS AND SEAS THEN DIMINISH WEDS AND THURS AS THE STORM MOVES FARTHER OUT TO SEA AND A HIGH PRESSURE RIDGE APPROACHES FROM THE WEST. && .HYDROLOGY... AN ADDITIONAL 1 TO 2 TENTHS OF AN INCH OF LIQUID EQUIVALENT THIS EVENING OVER LI/CT...HIGHEST EAST. THIS SHOULD FALL MAINLY AS SNOW. CURRENT FORECAST HAS ANYWHERE FROM AS LITTLE AS AROUND A TENTH OF AN INCH OF LIQUID EQUIVALENT PRECIPITATION TO A LITTLE OVER AN INCH IN ASSOCIATION WITH STORM AFFECTING THE REGION MONDAY NIGHT THROUGH TUESDAY. PRECIP TYPE HOWEVER DOES APPEAR TO BE MOSTLY ALL SNOW...REDUCING ADVERSE HYDROLOGIC IMPACTS DURING THE STORM. THERE IS STILL UNCERTAINTY WITH THESE AMOUNTS. ICE ON THE WALLKILL AND YANTIC RIVERS IS CAUSING MINOR FLUCTUATIONS IN RIVER LEVELS AT THIS TIME. && .TIDES/COASTAL FLOODING...
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A POTENTIAL INTENSE COASTAL STORM COULD BRING MINOR TO LOCALLY MODERATE COASTAL IMPACTS TO THE REGION MONDAY NIGHT INTO TUESDAY MORNING.
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&& .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR CTZ005>012. NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NYZ078>081-177-179. WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ068- 070>075-176-178. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST SUNDAY FOR ANZ330-335-338- 340-345-353-355. GALE WARNING UNTIL 11 PM EST THIS EVENING FOR ANZ350. && $$ SYNOPSIS...JC/NV NEAR TERM...NV SHORT TERM...NV LONG TERM...JC AVIATION...GOODMAN MARINE...JC/NV HYDROLOGY...JC/NV TIDES/COASTAL FLOODING...NV

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