Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 270329 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1029 PM EST MON JAN 26 2015 .SYNOPSIS... A POWERFUL NOREASTER WILL CONTINUE TO IMPACT THE REGION THRU TUE. HIGH PRESSURE BUILDS IN FOR WEDNESDAY...MOVES OVERHEAD WEDNESDAY NIGHT AND OFFSHORE ON THURSDAY. MEANWHILE...LOW PRESSURE OVER THE CENTRAL US TRACKS THROUGH THE GREAT LAKES THURSDAY AND ACROSS NEW ENGLAND ON FRIDAY. HIGH PRESSURE BUILDS BACK FOR THE WEEKEND AND THEN ANOTHER STORM SYSTEM COULD IMPACT THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... ONLY CHANGE FOR THIS UPDATES WAS TO TRIM BACK SNOWFALL AMOUNTS ABOUT 4 TO 6 INCHES WEST OF THE HUDSON RIVER BASED ON RADAR...HI- RES MODEL RUNS AND 00Z NAM. INDICATIONS ARE THAT WESTERN EXTENT OF HEAVIER AND MOST PERSISTENT BANDING MAY STALL ALONG THE NYC AND HUDSON RIVER...WITH SUBSIDENCE TO THE WEST OF THIS BAND. SHOULD HAVE A BETTER IDEA OF WESTERN EXTENT OF HEAVIER BANDING SET-UP AFTER 06Z...AND AT THAT TIME SNOWFALL AMOUNTS WILL LIKELY HAVE TO BE DROPPED TO THE WEST OF THAT BOUNDARY. IMPRESSIVE LIFT VIA CLOUD TOP COOLING OVER THE REGION AHEAD OF PIVOTING SHORTWAVE ENERGY AND COUPLED JET STRUCTURE...WITH A SUBTROPICAL MOISTURE TAP FROM THE PACIFIC...SEEN IN WATER VAPOR IMAGERY. AT THE SURFACE...989 LOW PRESSURE...ABOUT 200 MILES E OF THE DELMARVA...EXPECTED TO CONTINUE TO DEEPEN AND SLOWLY TRACK NE/N TO AROUND THE 40/70 LAT/LON BENCHMARK BY DAYBREAK. BANDS OF HEAVY SNOW WILL CONTINUE ADVECTING NW INTO LI/CT THROUGH THE OVERNIGHT...WITH SNOWFALL RATES PICKING UP. AS LARGER BANDS SOLIDIFY OVERNIGHT...RATES SHOULD PICK UP TO 2 TO 4 INCHES PER HOUR UNDER THOSE BANDS...WITH SOME LOCALLY HIGHER RATES POSSIBLE WITH CONVECTION. SO FAR HEAVIEST SNOW TOTALS HAVE BEEN RECEIVED ACROSS LI AND NYC WITH 4 TO 8 INCHES OF SNOW. WINDS CONTINUE TO INCREASE LATE THIS EVENING...WITH MAX GUSTS 40 TO 45 MPH BEING MEASURED ACROSS EASTERN LI AND CT...AND NEAR 40 MPH TO THE CITY. WINDS WILL CONTINUE TO INCREASE WITH GUSTS IN EXCESS OF 45-50 MPH OVERNIGHT INTO TUESDAY MORNING. ACROSS EXTREME ERN LI...WIND GUSTS OF 60-70 MPH POSSIBLE. SIGNIFICANT BLOWING AND DRIFTING OF SNOW OVERNIGHT INTO TUESDAY MORNING...WITH WHITEOUT CONDITIONS. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... IT SHOULD BE A RAGING BLIZZARD AT 6AM...WITH HVY SNOW...DAMAGING WINDS AND WHITEOUT CONDITIONS ACROSS MOST OF THE AREA. EXTREME NWRN ZONES SUCH AS ORANGE AND WRN PASSAIC MAY BE A BIT MARGINAL WRT WINDS. THE LOW ESSENTIALLY STALLS SOMEWHERE S OF CAPE COD DURING THE DAY...THEN DRIFTS AWAY TO THE NE TUE NGT BRINGING AND END TO THE STORM. DEPENDING ON EXACTLY WHERE THE STORM SETS UP...THERE IS THE POTENTIAL THAT THE DRY SLOT COULD WORK INTO THE REGION FROM THE N...CUTTING OFF THE HEAVIER PCPN WHERE THIS OCCURS. W OF THIS AREA WILL BE WHERE THE BEST DEFORMATION ZONE WILL BE. THE MODELS DIFFER ON THIS...WITH THE 18Z NAM PLACING THIS BAND OVER THE CITY. THE SNOWFALL FCST REMAINS IN THE 20-30 INCH RANGE WITH LOCALLY HIGHER AMTS. A LITTLE LESS FCST ACROSS NWRN ZONES...BUT THE LATEST NAM SUGGESTS EVEN OVER 2 FT INTO ORANGE COUNTY. THE MODEL PRODUCES 2.7 INCH LIQUID OVER THE BRONX...SO THERE IS DEFINITE 3 FT POTENTIAL WITH THIS SYS. WHERE EXACTLY THAT ULTIMATELY PLAYS OUT REMAINS TO BE SEEN. WRT TEMPS...THE GUIDANCE SEEMS TO BE PICKING UP THE PASSAGE OF A CSTL FRONT ON LI. FOR EXAMPLE...THE MET BRINGS TEMPS UP TO 41 DEGREES AT KFOK TNGT. THIS SEEMS UNREALISTIC ATTM WITH SUSTAINED 30KT NLY WINDS IN THE SAME GUIDANCE. AS A RESULT...TEMPS BLW GUIDANCE FOR THE EVENT. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... NOT MUCH CHANGE TO THE LONG TERM FORECAST AS MODEL GUIDANCE LOOKS SIMILAR TO PREVIOUS FORECAST. GENERAL H5 PATTERN OF RIDGING OUT WEST AND TROUGHING OVER THE EAST LOOKS TO CONTINUE THROUGH THE PERIOD. VORTEX DEVELOPS OVER HUDSON BAY LATE THIS WEEK WITH COLD CONDITIONS PERSISTING INTO EARLY NEXT WEEK. ONLY TIME PERIODS OF CONCERN WITH REGARDS TO PCPN ARE THU NIGHT INTO FRI AS A CLIPPER SYSTEM TRACKS ACROSS THE AREA...AND MON...ALTHOUGH THERE IS HIGH UNCERTAINTY WITH THIS SYSTEM. THERMAL PROFILES ARE COLD ENOUGH FOR SNOW THU NIGHT/FRI ALTHOUGH AMOUNTS WILL BE LIGHT. AS FOR MON...THE GFS IS MORE AMPLIFIED WITH THE H5 FLOW COME EARLY NEXT WEEK AND IS TRACKING A CLIPPER SYSTEM ACROSS THE GREAT LAKES WITH REDEVELOPMENT OFF THE MID ATLANTIC COAST. THE EC BEING FLATTER DEVELOPS A LOW OVER THE MID MISSISSIPPI VALLEY AND TRACKS IT EWD OFF THE MID ATLANTIC COAST AND OUT TO SEA. HAVE GONE BELOW GUIDANCE FOR LOWS WED NIGHT DUE TO A DEEP SNOWPACK ON THE GROUND AND GOOD RADIATIONAL COOLING CONDS EXPECTED WITH HIGH PRES BUILDING OHD. WINDS WILL BE LIGHT SO WIND CHILLS WILL ONLY BE A FEW DEGREES BELOW AMBIENT AIR TEMPS. TEMPS WILL GENERALLY BE IN THE 20S DURING THE DAY AND TEENS AT NIGHT...EXCEPT FOR WED NIGHT WHEN THEY MUCH OF THE AREA SHOULD DROP INTO SINGLE DIGITS AND THU/FRI WITH UPPER 20S TO LOWER 30S AND LOWER TO MID 30S RESPECTIVELY. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... ** HIGH IMPACT SNOW AND WIND EVENT TONIGHT INTO TUESDAY NIGHT ** IFR OR LOWER CONDS TONIGHT AND TUES WITH SNOW. NNE WINDS BACK TO NNW BY LATE TUES MORNING. GUSTS 30-40KT...DIMINISHING SOMEWHAT LATE TUES AFTN. 2-4 INCH PER HOUR SNOWFALL RATES COULD POTENTIALLY LAST UNTIL AROUND 12Z FOR THE CITY TERMINALS AND TERMINALS TO THE EAST...WITH A BETTER POTENTIAL OVER KISP/KBDR...WHICH COULD POTENTIALLY SEE SUCH RATES LATE MORNING AS WELL. SNOW BEGINS TO TAPER IN THE EVENING ALONG WITH DIMINISHING WINDS AND IMPROVING FLIGHT CATEGORIES. .OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY... .TUES NIGHT...MVFR IN THE EVENING...BCMG VFR BY LATE. N-NW WINDS G25-35KT. .WEDNESDAY...VFR. NW WINDS G25-30KT POSSIBLE. .WEDNESDAY NIGHT-THURSDAY...VFR. .THU NGT...MVFR OR LOWER CONDITIONS IN LGT SN. .FRI...CHC MVFR IN LGT SN IN THE AM. VFR WITH NW WNDS G25-30KT IN THE AFTN. .SAT...VFR. && .MARINE... 970S LOW WILL PRODUCE STORM TO HURRICANE FORCE COND TNGT AND TUE. WINDS WILL DIMINISH TO SCA LVLS TUE NGT. SEAS BUILD TO 16 TO 22 FT ON THE OCEAN AND 4 TO 8 FT ON THE SOUND. CONDS WILL BECOME SUB-ADVSY ON WED AS THE STORM CONTINUES TO PULL AWAY AND HIGH PRES BUILDS FROM THE W. THE HIGH WILL KEEP TRANQUIL CONDS ON THE WATERS THROUGH THU NIGHT AS THE HIGH MOVES OHD AND THEN OFFSHORE. SCA CONDS RETURN FRI INTO SAT AS A CLIPPER LOW INTENSIFIES OVER THE GULF OF MAINE AND STRONG HIGH PRES BUILDS FROM THE W. && .HYDROLOGY... LIQUID EQUIVALENT AMOUNTS OF 1.5 TO AROUND 2.25 INCHES WITH THE BLIZZARD. ICE ON THE WALLKILL AND YANTIC RIVERS IS CAUSING MINOR FLUCTUATIONS IN RIVER LEVELS AT THIS TIME. && .TIDES/COASTAL FLOODING... A COASTAL FLOOD WARNING IS IN EFFECT FOR NORTHERN LONG ISLAND AND WESTERN NY COAST WITHIN THE WESTERN LONG ISLAND SOUND...THE TWIN FORKS OF LONG ISLAND...AND THE SOUTH SHORE BAYS OF LONG ISLAND/NYC. COASTAL FLOOD ADVISORY IS IN EFFECT FOR NYC/NJ COAST ADJACENT TO NY HARBOR...AND THE CT COASTS. THE NOR`EASTER IS EXPECTED TO PRODUCE MODERATE COASTAL IMPACTS FOR PARTS OF THE REGION OVERNIGHT INTO EARLY TUESDAY MORNING HIGH TIDE. THERE`S THE POTENTIAL FOR FLOODING OF VULNERABLE SHORE ROADS AND/OR ADJACENT PROPERTIES DUE TO HEIGHT OF STORM TIDE AND/OR WAVE ACTION. THE MOST LIKELY SURGE FOR COASTAL AREAS IS: - WESTERN LONG ISLAND SOUND (NY ZONES)...2 1/2 TO 3 FT ABOVE THE ASTRONOMICAL TIDE...WITH A WORST CASE OF 3 1/2 FT. - LONG ISLAND SOUND CT COAST...2 TO 3 FT ABOVE THE ASTRONOMICAL TIDE...WITH A WORST CASE OF 3 1/2 FT. - THE TWIN FORKS OF LONG ISLAND...2 1/2 TO 3 FT ABOVE THE ASTRONOMICAL TIDE...WITH A WORST CASE OF 3 1/2 FT. - NEW YORK HARBOR AND THE SOUTH SHORE BAYS...2 1/2 TO 3 FT ABOVE THE ASTRONOMICAL TIDE...WITH A WORST CASE OF 3 1/2 FT. SIGNIFICANT BEACH EROSION AND WASHOVERS ARE EXPECTED ALONG OCEAN FACING BARRIER BEACHES OF LONG ISLAND DUE TO STORM TIDE AND 7 TO 12 FT WAVES WEST AND 10 TO 15 FT EAST. A FEW EXPOSED WATERFRONT STRUCTURES MAY BE DAMAGED. HIGH WAVES AND HIGH STORM TIDE WILL ALSO CAUSE BEACH EROSION ALONG NORTH FACING SHORELINES OF LONG ISLAND SOUND AND ALONG THE TWIN FORKS. A FEW EXPOSED WATERFRONT STRUCTURES MAY BE DAMAGED. && .CLIMATE... THIS BLIZZARD HAS THE POTENTIAL TO PRODUCE THE LARGEST SINGLE- STORM SNOWFALL IN NYC HISTORY. HERE ARE THE CURRENT TOP TEN SNOWFALLS FOR THE CITY... AMOUNT DATES 26.9 FEB 11-12 2006 25.8 DEC 26-27 1947 21.0 MAR 12-13 1888 20.9 FEB 25-26 2010 20.2 JAN 7-8 1996 20.0 DEC 26-27 2010 19.8 FEB 16-17 2003 19.0 JAN 26-27 2011 18.1 JAN 22-24 1935 AND MARCH 7-8 1941 18.0 DEC 26 1872 && .OKX WATCHES/WARNINGS/ADVISORIES... CT...BLIZZARD WARNING UNTIL MIDNIGHT EST TUESDAY NIGHT FOR CTZ005>012. COASTAL FLOOD ADVISORY UNTIL 7 AM EST TUESDAY FOR CTZ009>012. NY...COASTAL FLOOD WARNING UNTIL 7 AM EST TUESDAY FOR NYZ079-081. BLIZZARD WARNING UNTIL MIDNIGHT EST TUESDAY NIGHT FOR NYZ067>075-078>081-176>179. COASTAL FLOOD ADVISORY UNTIL 4 AM EST TUESDAY FOR NYZ072-074. COASTAL FLOOD WARNING UNTIL 6 AM EST TUESDAY FOR NYZ075-080- 178-179. COASTAL FLOOD WARNING FROM 3 AM TO 7 AM EST TUESDAY FOR NYZ071- 073-078-176-177. NJ...BLIZZARD WARNING UNTIL MIDNIGHT EST TUESDAY NIGHT FOR NJZ002- 004-006-103>108. COASTAL FLOOD ADVISORY UNTIL 4 AM EST TUESDAY FOR NJZ006-106- 108. MARINE...STORM WARNING UNTIL 6 PM EST TUESDAY FOR ANZ330-340-345-353- 355. GALE WARNING UNTIL 6 PM EST TUESDAY FOR ANZ335-338. HURRICANE FORCE WIND WARNING UNTIL NOON EST TUESDAY FOR ANZ350. && $$ SYNOPSIS...JMC/24 NEAR TERM...JMC/NV SHORT TERM...JMC LONG TERM...24 AVIATION...JC MARINE...JMC/24 HYDROLOGY...JMC/24 TIDES/COASTAL FLOODING...PW/NV CLIMATE...

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