Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 250302 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1002 PM EST SAT JAN 24 2015 .SYNOPSIS... RAPIDLY DEEPENING LOW PRESSURE IN THE GULF OF MAINE WILL TRACK UP INTO THE CANADIAN MARITIMES INTO SUNDAY...WITH A COLD FRONT MOVING ACROSS THE AREA DURING THE DAY 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/... ** BLACK ICE ON UNTREATED SURFACES OVERNIGHT ** PRECIPITATION HAS COME TO AN END OVER THE AREA...AND WITH NEGATIVE VORTICITY ADVECTION IN THE WAKE OF THE DEPARTING SHORTWAVE THAT SUPPORTED THE LAST BURST OF SNOW...HAVING SOME CLEARING THIS EVENING. A MID DECK WILL BUILD BACK IN LATE THIS EVENING/EARLY OVERNIGHT...THEN EXIT LATE. MAIN STORY THOUGH IS WITH RESIDUAL WATER ON MOST AREA ROADWAYS...AND TEMPERATURES FALLING MAINLY INTO THE 20S OVERNIGHT...EXCEPT TO AT OR JUST BELOW THE FREEZING MARK IN NYC...EXPECT BLACK ICE TO FORM ON NON-TREATED SURFACES. THIS COULD MAKE TRAVEL...INCLUDING WALKING...TREACHEROUS IN PLACES OVERNIGHT INTO EARLY SUNDAY MORNING. A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED FOR THE DEVELOPMENT OF BLACK ICE ON UNTREATED SURFACES. && .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 CONDITIONS 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/... NOTE ON LATEST MODEL TRENDS FOR STORM SYSTEM MONDAY-TUESDAY. THE 18Z AND 00Z NAM HAVE MOVED TO A TRACK/IMPACT SIMILAR TO THE 12Z GFS...WITH MOST OF THE IMPACT E OF THE CT/NY STATE LINE. THE 18Z GFS THOUGH HAS A SOLUTION SIMILAR TO THE 12Z ECMWF/CMC-GLOBAL/NAM WITH A POTENTIALLY POTENT STORM IMPACTING THE ENTIRE CWA. NO CHANGES TO PREVIOUS THINKING...WHICH FOLLOWS BELOW...BASED ON THESE TRENDS. 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 PRECIPITATION WOULD MOVE AT LEAST IN THE VICINITY OF THE CWA...PERHAPS LATE MONDAY NIGHT INTO TUESDAY MORNING. PRECIPITATION TYPE LOOKS LIKE TO BE ALL SNOW. RIGHT NOW ONLY A SLIGHT CHANCE THAT WARM AIR GETS WRAPPED INTO THIS SYSTEM AND CAUSES MIXED PRECIPITATION TYPES FOR EASTERN SECTIONS. SHOULD MODELS CONTINUE THE NW TREND OF THE STORM`S TRACK...PRECIPITATION 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 PRECIPITATION 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 PRECIPITATION MORE LIKELY TO BE SNOW...BUT MIXED PRECIPITATION NOT OUT OF THE QUESTION. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... ** HIGH IMPACT SNOW AND WIND EVENT POSSIBLE LATE MONDAY INTO TUESDAY NIGHT...SEE OUTLOOK FOR DETAILS ** LOW PRESSURE TRACKS THROUGH THE WESTERN CANADIAN MARITIME PROVINCES OVERNIGHT. A COLD FRONT CROSSES THE AREA ON SUNDAY. VFR THROUGH THE TAF PERIOD. WINDS ARE MAINLY WNW AROUND 10-15KT...WITH GUSTS TO AROUND 20KT THIS EVENING. WINDS BACK TO THE W OVERNIGHT AT 5-10KT THROUGHOUT. WNW WINDS G15-20KT BY LATE SUNDAY MORNING/EARLY AFTERNOON. WINDS THEN VEER TO THE NW AND THE GUSTS ABATE BY LATE AFTERNOON. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .SUNDAY EVENING...VFR. .LATE SUNDAY NIGHT/MONDAY MORNING. MVFR POSSIBLE IN -SN. E-NE WINDS G20-25KT POSSIBLE. .MONDAY AFTERNOON-TUESDAY NIGHT...IFR/LIFR CONDITIONS LIKELY IN SNOW...HIGHEST PROBABILITIES AT EASTERN TERMINALS. POTENTIAL FOR HEAVY SNOW WITH NE-N WINDS G35-45 KT. .WEDNESDAY...VFR. NW WINDS G25-35KT POSSIBLE. .WEDNESDAY NIGHT-THURSDAY...VFR. && .MARINE... GALE CONDITIONS APPEAR TO HAVE COME TO AN END ON ANZ-350...SO HAVE CONVERTED THE GALE TO AN SCA THERE...WITH THE SAME END TIME AS THE EXISTING SCA ELSEWHERE...22Z SUNDAY. MARGINAL SCA CONDITIONS WILL PERSIST ACROSS MOST WATERS THROUGH SUN AFT...WITH HIGHEST LIKELIHOOD THIS EVENING INTO SUNDAY MORNING. SEAS 4 TO 10 FT ON THE OCEAN WATERS...HIGHEST EAST OF MORICHES INLET OVERNIGHT. WINDS EXPECTED TO GRADUALLY FALL BELOW SCA SUN AFTERNOON INTO SUNDAY EVENING...AND SEAS ON THE COASTAL OCEAN WATERS FALLING BELOW SCA LEVELS FOR PROBABLY AT LEAST A BRIEF PERIOD 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... DRY INTO SUNDAY EVENING...THEN LIGHT LIQUID EQUIVALENT FALLING AS SNOW POSSIBLE FROM LATE SUNDAY NIGHT INTO MONDAY. CURRENT FORECAST HAS ANYWHERE FROM AS LITTLE AS AROUND A TENTH OF AN INCH OF LIQUID EQUIVALENT PRECIPITATION OVER FAR W ORANGE COUNTY...TO A LITTLE OVER AN INCH OVER EASTERN LONG ISLAND AND SE CT...IN ASSOCIATION WITH STORM AFFECTING THE REGION MONDAY AFTERNOON THROUGH TUESDAY. PRECIPITATION 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... A POTENTIAL INTENSE COASTAL STORM COULD BRING MINOR TO LOCALLY MODERATE COASTAL IMPACTS TO THE REGION MONDAY NIGHT INTO TUESDAY MORNING. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST SUNDAY FOR ANZ330-335-338- 340-345-350-353-355. && $$ SYNOPSIS...JC/NV NEAR TERM...MALOIT/JC/NV SHORT TERM...NV LONG TERM...MALOIT/JC AVIATION...MALOIT MARINE...MALOIT/NV/JC HYDROLOGY...MALOIT/NV/JC TIDES/COASTAL FLOODING...NV

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