A Surprisingly Severe Storm

I generally get my weather directly from the National Weather Service website, where in addition to the text forecast I make use of the "Hourly Weather Graph" and radar to decide the mode (bicycle, subway) and timing of my commute. When something big may be going on, I also read the detailed "Forecast Discussion," which includes the thinking behind the forecast, information about models not in agreement, possible changes as events develop, etc. I certainly did so over Christmas weekend, with travel planned for my immediate and extended family. But I couldn't remember when the forecast changed.

So I went through the archived "Forecast Discussion" from the NWS, and found the following. As late as Christmas Eve, the storm was expected to basically miss most of the NY metro, excluding eastern Long Island and Connecticut. On Christmas morning, the possibility of a 6 to 9 inch snowstorm was forecast, and a “Winter Storm Watch” was issued. Someone should have been watching, because Christmas afternoon it was suddenly upgraded to a “Blizzard Warning.” It was still expected to be a powerful but not devastating storm in NYC until just after noon on Sunday, the day the storm hit, when the snow accumulation totals were updated. Bottom line: this storm put out more fakes than Michael Vick, so it is no surprise that a stunned city and MTA shanked a punt to Desean Jackson. The four “Forecast Discussions” follow in full: bold and italics were added by me.  If you bore easily, just read those parts.

On Christmas Eve, it Didn’t Seem Like A Problem

FXUS61 KOKX 250033 AFDOKX

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 733 PM EST FRI DEC 24 2010

.SYNOPSIS... WEAK HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH CHRISTMAS NIGHT. A WEAK UPPER LEVEL DISTURBANCE WILL ALSO PASS OVER THE REGION CHRISTMAS DAY. LOW PRESSURE DEVELOPING ALONG THE SOUTHEAST COAST CHRISTMAS NIGHT WILL INTENSIFY AND MOVE NORTHEAST...PASSING CLOSE ENOUGH TO BRING SOME IMPACTS TO THE AREA FROM SUNDAY INTO MONDAY. HIGH PRESSURE WILL RETURN FROM MONDAY NIGHT INTO THURSDAY. A WARM FRONT MAY APPROACH THURSDAY NIGHT INTO FRIDAY.

&&

.NEAR TERM /THROUGH SATURDAY/... MINOR CHANGES MADE TO TEMPERATURES AND WINDS EARLY THIS EVENING. SLIGHTLY WINDIER CONDITIONS ARE SLOWING THE ONSET OF GOOD RADIATIONAL COOLING OVER CENTRAL AND EASTERN LONG ISLAND...SO RAISED TEMPS AND WIND SPEED FOR A FEW HOURS HERE. UP NORTH...TEMPS ARE COOLING A LITTLE FASTER OVER PORTIONS OF THE LOWER HUDSON VALLEY AND NORTHERN FAIRFIELD...SO BROUGHT TEMPS DOWN A FEW DEGREES THIS EVENING. NO CHANGES MADE TO OVERNIGHT LOWS.

HIGH PRESSURE OVER THE MID ATLANTIC STATES SLIDES INTO THE SOUTHEASTERN U.S. TONIGHT...WHILE THE STRONG MARITIME LOW OVER THE MARITIMES FINALLY PUSHES FAR ENOUGH AWAY TO ALLOW THE PRESSURE GRADIENT TO RELAX OVER THE AREA. MID LEVEL CLOUDS AHEAD OF AN UPPER LEVEL TROUGH OVER THE LOWER GREAT LAKES WILL MOVE INTO WESTERN PORTIONS OF THE CWA LATE TONIGHT. OTHERWISE CLEAR SKIES AND DIMINISHING WINDS WILL SUPPORT GOOD RADIATIONAL COOLING...WITH LOWS IN THE TEENS OVER THE HUDSON VALLEY...INTERIOR CONNECTICUT AND THE PINE BARRENS. LOWS WILL BE IN THE MID 20S OVER NYC AND NEARBY SUBURBS.

&&

.SHORT TERM /SATURDAY NIGHT/... SURFACE HIGH PRESSURE MOVES OFF THE SOUTHEAST COAST SATURDAY WHILE AN UPPER LEVEL TROUGH DIGS THROUGH THE GREAT LAKES. MID-LEVEL CLOUDS WILL INCREASE OVER THE AREA DURING THE DAY. ANY LIGHT PRECIP ASSOCIATED WITH THE UPPER LEVEL DISTURBANCE IS EXPECTED TO REMAIN TO THE WEST. MAV/MET GUIDANCE IN GOOD AGREEMENT FOR HIGH TEMPS...WHICH WILL BE IN THE LOW TO MID 30S ACROSS THE AREA.

THE UPPER TROUGH STRENGTHENS AND DEVELOPS A CUTOFF LOW OVER THE OHIO VALLEY SATURDAY NIGHT...WITH SURFACE LOW PRESSURE MOVING INTO THE OCEAN EAST OF THE CAROLINAS/GEORGIA. CLOUDS LOWER AND THICKEN SATURDAY NIGHT...WITH A SLIGHT CHANCE OF LIGHT SNOW POSSIBLE OVER ORANGE COUNTY. LOWS WILL BE A FEW DEGREES WARMER...RANGING FROM THE UPPER TEENS OVER INTERIOR SECTIONS TO MID TO UPPER 20S NEAR THE COAST.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/... PLENTY OF UNCERTAINTY ON DETAILS WITH THE STORM PROGGED TO DEVELOP OFF THE SOUTHEAST COAST SATURDAY NIGHT AND INTENSIFY AS IT MOVES EAST OF THE MID ATLANTIC AND NEW ENGLAND COASTS SUNDAY INTO SUNDAY NIGHT...WITH MODELS STILL STRUGGLING WITH PHASING DETAILS OF MULTIPLE SHORTWAVES AS THEY COMBINE TO CARVE OUT A DEEP CLOSED LOW BY SUNDAY...WITH A FULL SPECTRUM OF OUTCOMES RANGING FROM LITTLE OR NO PRECIP TO A MAJOR WINTER STORM. THE 12Z GFS...WHILE LOOKING MOST OMINOUS...WAS NOT FULLY ACCEPTED MAINLY DUE TO INITIALIZATION PROBLEMS WITH UPSTREAM MID LEVEL DISTURBANCES EXTENDING FROM CENTRAL CANADA INTO THE NORTHERN PLAINS...WHOSE INTERACTION WILL IN TURN GREATLY INFLUENCE THE EVOLUTION OF THE COASTAL STORM. THE 12Z ECMWF INITIALIZED THESE FEATURES A LITTLE BETTER BUT STILL NOT PERFECTLY...AND ITS SFC LOW TRACK SUNDAY NIGHT INTO MONDAY...WHILE RIDING A STRONG LOW LEVEL BAROCLINIC ZONE...STILL LOOKS A LITTLE TOO FAR EAST GIVEN THE STRONGER MID LEVEL FORCING LOCATED TO THE WEST.

AS A RESULT...THE MOST LIKELY OUTCOME AND COURSE OF LEAST REGRET IS EITHER STRAIGHT CONTINUITY FROM THE PREVIOUS FORECAST...OR A BLEND OF THE 06Z GFS AND 00Z ECMWF...WITH A LOW TRACK CLOSE ENOUGH TO DELIVER ADVISORY CRITERIA SNOWS TO SOUTHEAST CT AND EASTERN LONG ISLAND...LESSER AMOUNTS WESTWARD TO SW CT AND NYC METRO...AND LITTLE IF ANY ACCUMULATION WELL NORTH AND WEST OF NYC. IT SHOULD BE NOTED THAT THE PROBABILITY OF A SIGNIFICANT SNOWSTORM WITH AMOUNTS OVER 6 INCHES IS STILL NONZERO BUT IS LOW...ONLY 30-40 PERCENT FOR EASTERNMOST CT/LONG ISLAND...AND 10-20 PERCENT FARTHER WEST. FORECAST DETAILS MAY STILL BE SUBJECT TO SIGNIFICANT CHANGES IN EITHER DIRECTION AS CONFIDENCE IN THE INTERACTION OF THE MULTIPLE SHORTWAVES TO FORM THIS SYSTEM INCREASES...SO STAY TUNED.

HIGH PRESSURE WILL BUILD INTO THE REGION FOR WED/THU WITH DRY CONDITIONS AND HIGH TEMPS RIGHT AROUND NORMAL...TOPPING OFF IN THE UPPER 30S AND LOWER 40S. GFS INDICATES A WARM FRONTAL APPROACH THU NIGHT-FRI WHILE ECMWF KEEPS THE FRONT WELL TO THE WEST...WILL TAKE THE MIDDLE GROUND AND FORECAST ONLY SLIGHT CHANCE POP FOR SOME LIGHT PRECIP AT THAT TIME. SLIGHTLY WARMER ON FRI WITH HIGHS IN THE LOWER AND MID 40S.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... HIGH PRESSURE REMAINS IN CONTROL THROUGH FORECAST PERIOD.

VFR. NW TO N WINDS BELOW 10 KT EXPECTED. NY METRO ENHANCED AVIATION WEATHER SUPPORT DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)

KJFK FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED

KLGA FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED

On Christmas morning, looks like a possible significant snow event after all. Winter storm watch issued.

000 FXUS61 KOKX 251521 AFDOKX

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1021 AM EST SAT DEC 25 2010

.SYNOPSIS... WEAK HIGH PRESSURE WILL BE OVER THE AREA TODAY...WHILE A VIGOROUS UPPER TROUGH DEEPENS ACROSS THE TENNESSEE AND OHIO VALLEYS. LOW PRESSURE DEVELOPING ALONG THE SOUTHEAST COAST WILL INTENSIFY IN RESPONSE TO THE UPPER TROUGH AND MOVE NORTHEAST TONIGHT INTO SUNDAY...PASSING SOUTHEAST OF MONTAUK POINT SUNDAY NIGHT INTO MONDAY MORNING. LOW PRESSURE MOVES NEAR NOVA SCOTIA MONDAY NIGHT AS HIGH PRESSURE RETURNS FROM THE WEST. THIS HIGH WILL SLOWLY MOVE ACROSS THE AREA THROUGH THURSDAY. A WARM FRONT MAY APPROACH THURSDAY NIGHT INTO FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH PRESSURE BUILDS OFFSHORE OF THE SOUTHEASTERN U.S. AS AN UPPER LEVEL TROUGH MOVES TOWARDS THE SOUTHEAST U.S. A WEAK PRESSURE GRADIENT IN PLACE WILL ALLOW FOR LIGHT WINDS BUT WITH CLOUDS INCREASING FROM MID AND HIGH LEVELS...BELOW NORMAL TEMPS BY A FEW DEGREES CAN BE EXPECTED....MOSTLY IN LOW TO MID 30S IN ACCORDANCE WITH MAV/MET BLEND.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... FOR TONIGHT...LOWS NEAR NORMAL IN MID TO UPPER 20S GENERALLY WITH OVERCAST SKIES WITH LOWERING THICKENING CLOUDS AND LIGHT PRESSURE GRADIENT STILL IN PLACE. LOWS SLIGHTLY COLDER OUTLYING AREAS WITH RADIATIONAL COOLING.

UPPER LEVEL TROUGH DEEPENS IN SOUTHEAST U.S. TONIGHT AS SURFACE LOW PRESSURE MOVES FROM NEAR FLORIDA PANHANDLE TO OFFSHORE OF CAROLINAS. JET STREAM PHASING BETWEEN NORTHERN AND SOUTHERN BRANCHES OFF THE SOUTHEAST COAST WILL RESULT IN INTENSIFYING JET OF NEAR 100 KT. THIS WILL LEAD TO GREATER DIVERGENCE ALOFT...ALLOWING FOR OMEGA FIELD TO INCREASE AS LOW PRESSURE DEEPENS AT THE SURFACE. MODELS IN PRETTY GOOD AGREEMENT WITH THIS THROUGH TONIGHT. THEREAFTER...SOME DIFFERENCES ARISE AS THE UPPER LEVEL TROUGH CLOSES OFF AND THE SURFACE LOW DEEPENS.

BY SUNDAY MORNING AND AFTERNOON...THE SURFACE LOW WILL CONTINUE TO DEEPEN AND MOVE IN A NORTHEAST DIRECTION AS UPPER LEVEL TROUGH CLOSES OFF. DECREASING WAVELENGTH BETWEEN TROUGH AND RIDGE DOWNSTREAM WILL FAVOR CONTINUING OFFSHORE CYCLOGENESIS. SNOW COULD START AS EARLY AS SUNDAY MORNING BUT MOST OF WILL FALL SUNDAY AFTERNOON THROUGH SUNDAY NIGHT TIMEFRAME COINCIDING WITH THE APPROACH OF THE OMEGA FIELD AND RAPID DEEPENING OF THE LOW PRESSURE. GENERALLY GFS AND ECMWF ARE SIMILAR WITH THE ECMWF SHOWING A LARGE CHANGE BETWEEN 12Z AND 00Z RUNS FROM MORE OFFSHORE TO CLOSER TO COAST. THE NAM...GEM...AND UKMET ARE FARTHER OFFSHORE WITH THE SURFACE LOW WITH THE SREF IN BETWEEN AND CLOSE TO THE 40N/70W BENCHMARK. THE SREF HAS TRENDED HIGHER WITH PROBABILITY OF MEASURABLE PRECIP AS WELL. THE TRACK STILL HAS UNCERTAINTY AS GFS O6Z RUN TRENDED A LITTLE FARTHER TO THE WEST. THIS COULD HAVE RESULTING CHANGES TO QPF AMOUNTS AND RAIN/SNOW LINE WITH THE FORECAST IF THIS TREND HOLDS WITH OTHER MODEL GUIDANCE.

THEREFORE...POPS INCREASED LIKELY TO CATEGORICAL FOR SUNDAY AFTERNOON AND NIGHT AND WITH A BLEND OF HPC/SREF/NAM QPF AS WELL AS ACCOUNTING FOR AROUND 10 TO 1 SNOW TO LIQUID RATIOS...SNOW COULD ACCUMULATE GENERALLY 6 TO 9 INCHES WITH LOCALLY HIGHER AMOUNTS ESPECIALLY FARTHER EAST OR IF MESOSCALE ENHANCED BANDING SETS UP. QPF AND SNOWFALL AMOUNTS ARE IN A NW TO SE GRADIENT WITH HIGHER TOTALS TOWARDS THE SOUTHERN AND EASTERN PORTIONS. THINK THAT PLACES FARTHER SOUTH AND EAST WILL HAVE MORE OF A HEAVY WET SNOW. WINTER STORM WATCH WAS ISSUED WITH HIGHER CONFIDENCE AS MODEL AGREEMENT HAS INCREASED COMPARED TO PREVIOUS MODEL RUNS ESPECIALLY WITH ECMWF TRENDING CLOSER TO THE COAST. STEEP GRADIENT IN PRESSURE AS LOW PRESSURE DROPS DUE TO BAROCLINICITY WILL ALSO RESULT IN VERY GUSTY WINDS 35 TO 40 MPH...WITH HIGHER CHANCE OF THESE WINDS TOWARDS THE COAST FOR SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON. NEAR BLIZZARD CONDITIONS ARE POSSIBLE ESPECIALLY FOR EASTERN SECTIONS.

DEEP SURFACE LOW PASSES FROM EAST OF CAPE COD TOWARDS NOVA SCOTIA ON MONDAY AFTERNOON AND NIGHT...WITH SNOW GRADUALLY DURING THE AFTERNOON. WINDS WILL GRADUALLY SUBSIDE BY LATER MONDAY NIGHT AS LOW PRESSURE MOVES FARTHER AWAY AND GIVES WAY TO HIGH PRESSURE STARTING TO BUILD IN FROM SOUTHEAST U.S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION FOR TUES NIGHT THROUGH THU WITH DRY CONDITIONS AND HIGH TEMPS RIGHT AROUND NORMAL...TOPPING OFF IN THE UPPER 30S AND LOWER 40S. GFS INDICATES A WARM FRONTAL APPROACH THU NIGHT-FRI WHILE ECMWF KEEPS THE FRONT WELL TO THE WEST...WILL TAKE THE MIDDLE GROUND AND FORECAST ONLY SLIGHT CHANCE POP FOR SOME LIGHT PRECIP AT THAT TIME. SLIGHTLY WARMER ON FRI WITH HIGHS IN THE LOWER AND MID 40S.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... HIGH PRES MOVES THROUGH THE REGION TODAY AND OFFSHORE TONIGHT.

VFR. N TO NW WINDS AT 5-10 KT THROUGH EARLY AFTERNOON.....THEN WINDS DIMINISH TO 5 KT OR LESS. WINDS TURN NE AFTER MIDNIGHT TONIGHT...GENERALLY AT 5-7 KT. CIGS BKN100 WILL THICKEN AND LOWER TO OVC040 LATE TONIGHT AS WELL.

FOR THE 30 HOUR TAF SITES (KJFK/KEWR/KSWF): NE WINDS INCREASE TO 10-15 KT WITH 15-20 KT GUSTS SUN MORNING. SOME LIGHT SNOW WILL MOVE INTO THE TERMINALS...RESULTING IN LOWERING CONDITIONS. FOR NOW... WILL CARRY MVFR CIGS...BUT THIS COULD DROP TO IFR OR LOWER DEPENDING ON THE TRACK OF THE STORM.

OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...

SUN-MON...THERE IS THE POTENTIAL FOR A WINTER STORM SUNDAY THROUGH MONDAY MORNING WITH IFR AND LOWER CONDITIONS...HEAVY SNOW RESULTING IN SIGNIFICANT SNOW ACCUMULATION...AND STRONG NORTHERLY WINDS. STRONG NW FLOW SETS UP FOR MON AFTERNOON AND MON NIGHT. TUE...VFR...GUSTY NW WINDS. WED...VFR.

&&

.MARINE... TRANQUIL CONDITIONS ON TAP THROUGH SUN MORNING AS HIGH PRES BUILDS THROUGH THE WATERS...AND THEN OFFSHORE.

A RAPIDLY DEVELOPING AND INTENSE COASTAL STORM WILL DEVELOP OVER THE MID-ATLANTIC COAST ON SUNDAY...TRACK TO A POINT ABOUT 100 MILES EAST OF ATLANTIC CITY BY SUNDAY EVENING...THEN TOWARD CAPE COD BY MONDAY MORNING. A PROLONGED PERIOD OF GALE FORCE WINDS IS EXPECTED SUNDAY AFTERNOON THROUGH AT LEAST MONDAY WITH A CHANCE FOR STORM FORCE WINDS SUNDAY NIGHT. MODELS HAVE COME INTO BETTER CONSENSUS WITH REGARDS TO THIS STORM...SO WILL ISSUE A GALE WATCH FOR SUNDAY AFTERNOON THROUGH MONDAY. GALES WILL LIKELY PERSIST INTO TUESDAY...BUT FUTURE SHIFTS CAN ADJUST ANY GALE WATCHES AND/OR WARNINGS AS NECESSARY.

IN ADDITION TO THE STRONG WINDS...HEAVY SNOW...POSSIBLY MIXED WITH RAIN OVER THE COASTAL OCEAN WATERS...WILL REDUCE VSBY TO 1 NM OR LESS SUNDAY AFTERNOON THROUGH MONDAY MORNING.

THERE IS STILL THE CHANCE THAT THE TRACK OF THIS STORM CAN CHANGE ONCE AGAIN...RESULTING IN A DIFFERENCE FORECAST. PLAY STAY TUNED TO THE LATEST DETAILS.

&&

.HYDROLOGY... NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH SUNDAY MORNING SNOW SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON WILL GENERALLY YIELD LIQUID EQUIVALENT AMOUNTS OF 0.6 TO NEAR 1 INCH...ESPECIALLY ACROSS SOUTHEAST CT AND EASTERN LONG ISLAND. NO HYDROLOGIC IMPACTS ARE EXPECTED DUE TO ITS FROZEN STATE...AND LITTLE SUBSEQUENT MELTING OF ANY SNOW PACK AS LONG TERM HIGH TEMPS BARELY REACH THE LOWER 40S MAINLY IN URBAN/COASTAL SECTIONS DURING MID TO LATE WEEK.

&&

.OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR CTZ005>012. NY...WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR NYZ067>075-078>081-176>179. NJ...WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON FOR NJZ002-004-006-103>108. MARINE...GALE WATCH FROM SUNDAY MORNING THROUGH MONDAY AFTERNOON FOR ANZ330-335-338-340-345-350-353-355.

Christmas Afternoon: BLIZZARD WARNING FIRST ISSUED!

000 FXUS61 KOKX 252021 AFDOKX

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 321 PM EST SAT DEC 25 2010

...POWERFUL WINTER STORM TO BRING BLIZZARD CONDITIONS TO NYC METRO...LONG ISLAND AND MUCH OF SOUTHERN CONNECTICUT...

.SYNOPSIS... WEAK HIGH PRESSURE WILL BE OVER THE AREA THROUGH TONIGHT. LOW PRESSURE DEVELOPING ALONG THE SOUTHEAST COAST WILL INTENSIFY AND MOVE NORTHEAST TONIGHT INTO SUNDAY...PASSING SOUTHEAST OF MONTAUK POINT SUNDAY NIGHT INTO MONDAY MORNING. THE LOW WILL THEN MOVE NEAR NOVA SCOTIA MONDAY NIGHT AS HIGH PRESSURE RETURNS FROM THE WEST. THIS HIGH WILL SLOWLY MOVE ACROSS THE AREA THROUGH THURSDAY. A WARM FRONT MAY APPROACH THURSDAY NIGHT INTO FRIDAY.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... HIGH PRESSURE WILL BUILD OFF THE SOUTHEAST COAST AS AN UPPER LEVEL TROUGH ALSO MOVES TOWARD THE SOUTHEAST STATES. A WEAK PRESSURE GRADIENT IN PLACE WILL ALLOW FOR LIGHT WINDS BUT WITH CLOUDS INCREASING FROM MID AND HIGH LEVELS...BELOW NORMAL TEMPS BY A FEW DEGREES CAN BE EXPECTED....MOSTLY IN LOW TO MID 30S IN ACCORDANCE WITH MAV/MET BLEND. PER LATEST RADAR RETURNS OVER EASTERN PA...AREAS WELL NORTH/WEST OF NYC COULD SEE AN ISOLD SNOW SHOWER THIS AFTERNOON AND EVENING.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... WE WILL BE ISSUING BLIZZARD WARNINGS FOR MUCH OF THE CWA...AND WINTER STORM WARNINGS FOR THE LOWER HUDSON VALLEY...FOR THE INTENSE STORM PROGGED TO IMPACT THE AREA FROM SUNDAY INTO MONDAY AFTERNOON. EXPECTATION IS FOR HEAVY SNOW TO DEVELOP EARLIER THAN EXPECTED...BY MID TO LATE AFTERNOON SUNDAY...AND CONTINUE INTO MUCH OF SUNDAY NIGHT. TOTAL ACCUMULATIONS SHOULD RANGE FROM 8-12 INCHES NW OF NYC AND 12-16 INCHES MOST ELSEWHERE...WITH HIGHER LOCAL AMOUNTS WHERE BEST MESOSCALE BANDING SETS UP. STILL COULD BE SOME MIXING ISSUES ACROSS EASTERN LONG ISLAND AND SOUTHEAST CT.

NORTHERLY WINDS WILL GUST WELL OVER 35 MPH OVER MOST OF THE BLIZZARD WARNING AREA...APPROACHING 50-55 MPH OVER CENTRAL AND EASTERN LONG ISLAND AT THE HEIGHT OF THE STORM...WITH CONSIDERABLE BLOWING/DRIFTING SNOW AND VERY POOR VSBY.

MORE DETAILS TO FOLLOW BY ABOUT 4 PM.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION FOR TUES NIGHT THROUGH THU WITH DRY CONDITIONS AND HIGH TEMPS RIGHT AROUND NORMAL...TOPPING OFF IN THE UPPER 30S AND LOWER 40S. GFS INDICATES A WARM FRONTAL APPROACH THU NIGHT-FRI WHILE ECMWF KEEPS THE FRONT WELL TO THE WEST...WILL TAKE THE MIDDLE GROUND AND FORECAST ONLY SLIGHT CHANCE POP FOR SOME LIGHT PRECIP AT THAT TIME. SLIGHTLY WARMER ON FRI WITH HIGHS IN THE LOWER AND MID 40S.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/... A MAJOR WINTER STORM WILL IMPACT THE TERMINALS SUNDAY THROUGH MONDAY WITH HEAVY SNOW AND HIGH WINDS.

VFR CONDITIONS OVERNIGHT WILL RAPIDLY DETERIORATE AFTER 12Z WITH THE ONSET OF LIGHT SNOW IN THE MORNING. MVFR CIGS DEVELOP AROUND THIS TIME AND THEN DETERIORATE TO IFR TOWARD 18Z. INTENSITY OF THE SNOW WILL ALSO BEGIN TO PICK UP DURING THE LATE MORNING AND EARLY AFTERNOON HOURS.

A LIGHT N TO NE FLOW OVERNIGHT WILL RAMP UP QUICKLY IN THE 12Z TO 18Z TIME FRAME...WITH GUSTS UP TO 25 KT ALONG THE COAST.

CONFIDENCE IS HIGH FOR LOW CIGS/HIGH WINDS ON SUN...BUT TIMING MAY BE OFF TOWARD THE END OF THE TAF PERIOD PLUS OR MINUS A COUPLE OF HOURS. POTENTIAL FOR MIXED PCPN AT KGON AND KISP AFTER 18Z.

MODERATE TO HEAVY SNOWFALL DEVELOPS FOR 30-HR TAF SITES AT KJFK AND KEWR WITH GUSTS UP TO 35 KT BETWEEN 20Z AND 00Z MON. VSBYS WILL BE NEAR ZERO WITH INCH TO TWO INCH AN HOURS SNOWFALL RATES,

OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...

SUN AFT-MON...HEAVY SNOW AND STRONG NLY WINDS WITH GUSTS UP TO 45 KT POSSIBLE AT THE COAST SUN NIGHT INTO MON MORNING. MIXING WITH SLEET OR RAIN MAY OCCUR AT KGON AND KISP IN THE EVENING. MODERATE TO HEAVY SNOW ENDS BY 06Z MON...WITH CIGS GRADUALLY IMPROVING TO MVFR/VFR BY LATE MON MORNING. HOWEVER...A STRONG NW FLOW CONTINUES WITH GUSTS UP TO 35 KT THROUGHOUT MON. TUE...VFR...GUSTY NW WINDS. WED AND THU...VFR.

&&

.MARINE... TRANQUIL CONDITIONS ON TAP THROUGH SUN MORNING AS HIGH PRES BUILDS THROUGH THE WATERS...AND THEN OFFSHORE.

A RAPIDLY DEVELOPING AND INTENSE COASTAL STORM WILL DEVELOP OVER THE MID-ATLANTIC COAST ON SUNDAY...TRACK TO A POINT ABOUT 100 MILES EAST OF ATLANTIC CITY BY SUNDAY EVENING...THEN TOWARD CAPE COD BY MONDAY MORNING. A PROLONGED PERIOD OF GALE FORCE WINDS IS EXPECTED SUNDAY AFTERNOON THROUGH AT LEAST MONDAY WITH A CHANCE FOR STORM FORCE WINDS SUNDAY NIGHT. MODELS HAVE COME INTO BETTER CONSENSUS WITH REGARDS TO THIS STORM...SO WILL ISSUE A GALE WATCH FOR SUNDAY AFTERNOON THROUGH MONDAY. GALES WILL LIKELY PERSIST INTO TUESDAY... BUT FUTURE SHIFTS CAN ADJUST ANY GALE WATCHES AND/OR WARNINGS AS NECESSARY.

IN ADDITION TO THE STRONG WINDS...HEAVY SNOW...POSSIBLY MIXED WITH RAIN OVER THE COASTAL OCEAN WATERS...WILL REDUCE VSBY TO 1 NM OR LESS SUNDAY AFTERNOON THROUGH MONDAY MORNING.

THERE IS STILL THE CHANCE THAT THE TRACK OF THIS STORM CAN CHANGE ONCE AGAIN...RESULTING IN A DIFFERENCE FORECAST. PLAY STAY TUNED TO THE LATEST DETAILS.

&&

.HYDROLOGY... NO SIGNIFICANT PRECIPITATION IS EXPECTED THROUGH SUNDAY MORNING. SNOW SUNDAY AFTERNOON THROUGH MONDAY AFTERNOON WILL GENERALLY YIELD LIQUID EQUIVALENT AMOUNTS OF 0.6 TO NEAR 1 INCH...ESPECIALLY ACROSS SOUTHEAST CT AND EASTERN LONG ISLAND. NO HYDROLOGIC IMPACTS ARE EXPECTED DUE TO ITS FROZEN STATE...AND LITTLE SUBSEQUENT MELTING OF ANY SNOW PACK AS LONG TERM HIGH TEMPS BARELY REACH THE LOWER 40S MAINLY IN URBAN/COASTAL SECTIONS DURING MID TO LATE WEEK.

&&

.TIDES/COASTAL FLOODING... LATEST GFS STORM SURGE GUIDANCE IS OFF THE CHARTS WITH 3-6 FT DEPARTURES FOR LATE SUNDAY NIGHT...HIGHEST FOR LONG ISLAND SOUND. FROM PAST EXPERIENCE THIS LOOKS MUCH TOO HIGH GIVEN EXPECTED NORTHERLY FLOW...AND DEPARTURES OF 2-3 FT SEEM MORE LIKELY. THIS COULD RESULT IN WIDESPREAD MINOR TO LOCALLY MODERATE COASTAL FLOODING AROUND THE TIMES OF HIGH TIDE LATE SUNDAY NIGHT...AND A COASTAL FLOOD WATCH MAY BECOME NECESSARY FOR SOME SPOTS...IN PARTICULAR THE SOUTH SHORE BAYS OF WESTERN LONG ISLAND AND WESTERNMOST LONG ISLAND SOUND. STAY TUNED.

&&

.OKX WATCHES/WARNINGS/ADVISORIES... CT...BLIZZARD WARNING FROM 6 AM SUNDAY TO 6 PM EST MONDAY FOR CTZ007>012. WINTER STORM WARNING FROM 6 AM SUNDAY TO 6 PM EST MONDAY FOR CTZ005-006. NY...BLIZZARD WARNING FROM 6 AM SUNDAY TO 6 PM EST MONDAY FOR NYZ071>075-078>081-176>179. WINTER STORM WARNING FROM 6 AM SUNDAY TO 6 PM EST MONDAY FOR NYZ067>070. NJ...BLIZZARD WARNING FROM 6 AM SUNDAY TO 6 PM EST MONDAY FOR NJZ002-004-006-103>108. MARINE...GALE WARNING FROM 3 PM SUNDAY TO 6 PM EST MONDAY FOR ANZ330- 335-340-345. GALE WARNING FROM 6 PM SUNDAY TO 6 PM EST MONDAY FOR ANZ338. STORM WARNING FROM NOON SUNDAY TO 6 AM EST MONDAY FOR ANZ350- 353-355.

&& $$ SHORT TERM/HAZARDS UPDATE...GOODMAN

NOTE: MAY HAVE BEEN NEW FORECASTER ON DUTY

NEW YORK OFFICIALS HAVE ABOUT 27 HOURS TO REACT BEFORE ALL HELL BREAKS LOOSE 6 PM SUNDAY

Sunday Morning: Still Only Expecting A Serious But Not Devastating Storm. Told the wife and teenage daughters to stay put Sunday. Got an argument, but they did so.

000 FXUS61 KOKX 260956 AFDOKX

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 456 AM EST SUN DEC 26 2010

.SYNOPSIS... A DEVELOPING WINTER STORM OFF THE CAROLINA COAST WILL MOVE NORTHEAST TO JUST SOUTH OF LONG ISLAND TONIGHT BRINGING BLIZZARD CONDITIONS TO MOST OF THE REGION. THE STORM WILL MOVE INTO THE CANADIAN MARITIMES ON MONDAY. HIGH PRESSURE WILL RETURN FOR THE MIDDLE OF THE WEEK.

&&

.NEAR TERM /UNTIL NOON TODAY/... DRY AT 9Z WITH BAND OF PCPN BEGINNING TO TAKE SHAPE OVER THE DELMARVA AND STRETCHING NEWD. WATER VAPOR INDICATES THIS IS THE WAA ZONE. TD/S STILL IN THE TEENS AND LOWER 20S ACROSS THE CWA. WITH MAIN LIFT S OF THE CWA AND MOISTURE LIMITED OVER THE CWA...WILL KEEP IT MAINLY DRY AT SUNRISE..WITH LIGHT SNOW DEVELOPING FROM SE TO NW THROUGH NOON.

&&

.SHORT TERM /NOON TODAY THROUGH TUESDAY/... NO CHANGES TO THE WINTER STORM HEADLINES...YET.

TWO MAIN FCST ISSUES THIS MORNING. FIRST IS THE WIND. SECOND IS THE POTENTIAL FOR RAIN ACROSS ERN LI.

MODEL STORM TRACK HAS CONSOLIDATED WITH THE 00Z RUNS. THE ECMWF TRACKS ALONG THE 3Z SREF. GFS ABOUT 20MI NW OF THE ECMWF...AND THE NAM SLIGHTLY E OF THE ECMWF. QPF AND RESULTANT SNOWFALL FCST RELATIVELY UNCHANGED WITH A GENERAL 6-18 INCHES LIKELY. LEAST AMOUNTS ACROSS THE W AND HIGHEST AMOUNTS E...WHERE RAIN DOESNT HOLD THE NUMBERS DOWN.

WITH REGARD TO THE RAIN...CLOSE PROXIMINTY TO THE LOW MAY ALLOW FOR THE COASTAL FRONT TO PENETRATE WWD INTO ECNTRL LI. THE TWIN FORKS ARE MOST SUSCEPTIBLE. AS THE LOW MAKES IT/S CLOSEST APPROACH HOWEVER IT UNDERGOES OCCLUSION. IT SHOULD BE NOTED THAT H85 TEMPS NEVER RISE ABOVE FREEZING ACROSS THE CWA. FOR THIS REASON HAVE KEPT THE AREA MOSTLY SNOW BUT THERE REMAINS UNCERTAINTY. ANYWHERE FROM CNTRL LI WWD WILL BE ALL SNOW.

THE DEEP LOW WILL PRODUCE A POTENTIALLY DAMAGING WIND FIELD. BL WINDS IN THE GFS OVER 60KT. NAM WIND FIELDS ARE WEAKER...BUT THE DEEPER ECMWF GIVES SUPPORT TO THE GFS. FOR THIS REASON HAVE BUMPED WIND GUSTS UP TO 45-60 MPH. LOCALLY HIGHER GUSTS POSSIBLE ACROSS MOST OF LI. HAVE KEPT THE WARNINGS INTACT...BUT WILL INCLUDE WORDING STATING THAT AN UPGRADE TO A BLIZZARD WARNING IS POSSIBLE. BECAUSE THE HIGHEST WINDS...ESPECIALLY ACROSS THE INTERIOR...WILL BE TONIGHT...THERE IS STILL TIME TO OBSERVE WHAT ENSUES OVER THE OCEAN.

THE STORM WINDS DOWN MONDAY WITH STRONG WINDS CONTINUING. THE ACCUMULATING SNOW APPEARS IT WILL BE OVER BY 15Z ATTM. DRY WITH LESS WIND TUE.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... NO CHANGES...

NORTHWEST FLOW BEGINS TO DIMINISH ON TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION AND THE PRESSURE GRADIENT RELAXES. TUES NIGHT THROUGH THU SHOULD BE DRY CONDITIONS AND HIGH TEMPS RIGHT AROUND NORMAL...TOPPING OFF IN THE UPPER 30S AND LOWER 40S. GFS INDICATES A WARM FRONTAL APPROACH THU NIGHT-FRI WHILE ECMWF KEEPS THE FRONT WELL TO THE WEST...WILL TAKE THE MIDDLE GROUND AND FORECAST ONLY SLIGHT CHANCE POP FOR SOME LIGHT PCPN AT THAT TIME. SLIGHTLY WARMER ON FRI AND SAT WITH HIGHS IN THE LOWER AND MID 40S. PCPN CHANCES BEGIN TO INCREASE LATE SAT AS A SFC SYSTEM APPROACHES FROM THE OHIO VALLEY.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/... A MAJOR WINTER STORM WILL IMPACT THE TERMINALS SUNDAY AFTERNOON THROUGH MONDAY WITH HEAVY SNOW AND HIGH WINDS.

VFR CONDITIONS THROUGH EARLY MORNING. CIGS LOWER TO MVFR WITH VERY LIGHT NON ACCUMULATING SN IN THE LATE MORNING. EXPECT SN TO BLOSSOM ON THE LOCAL RADAR AROUND MID DAY RESULTING IN A RAPID DETERIORATION OF CONDITIONS TO IFR AND THEREAFTER BELOW IFR.

BANDED +SN TO THE NW OF THE SFC LOW IS LIKELY WITH THIS STORM AS ITS PRESSURE FALLS RAPIDLY. THIS BAND MAY LIKELY BE OVER THE NY METRO WITH 1+" PER HOUR SN RATE POSSIBLE AFTER 19Z AND MORE LIKELY BY 21Z. THUNDER SNOW POSSIBLE (NOT IN TAF) IN THE BAND.

SNOW TOTALS OF 12-15" EXPECTED.

NLY WINDS BUILD IN THE AFTN ON SUNDAY WITH PEAK GUSTS UP TO 50 KT NOT OUT OF THE QUESTION IN THE 00-03Z MON TIME FRAME. MOST GUSTS UP TO 45 KT SUN NIGHT WITH MODERATE TO HEAVY SNOW. THIS MODERATE TO HEAVY SNOW ENDS BY AROUND 06Z MON.

OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...

LATE SUN NGT-MON...MOSTLY LIGHT SNOW WITH NO ACCUMULATING SN ON MONDAY DAYTIME...BUT BLSN IN NW 30 G 45 KT WND. CIGS GRADUALLY IMPROVING TO MVFR/VFR BY LATE MON MORNING. UE...VFR...GUSTY NW WINDS. WED AND THU...VFR.

&&

.MARINE... ALL WATERS UPGRADED TO STORM. PEAK WINDS WILL BE AFTER DARK. STORM FORCE WINDS MAY NOT OCCUR OUTSIDE OF THE OCEAN UNTIL THE TONIGHT PERIOD...WITH MAINLY GALE FORCE WINDS LATE THIS AFTERNOON.

THEREAFTER...GALES CONTINUE FROM MON INTO TUE...FOLLOWED BY GRADUALLY DIMINISHING WINDS TUE NIGHT.

&&

.HYDROLOGY... SNOW SUNDAY THROUGH MONDAY AFTERNOON WILL GENERALLY YIELD LIQUID EQUIVALENT AMOUNTS OF 0.75 TO 1.50 INCHES...HEAVIEST FROM NYC EAST INTO SOUTHERN CT AND EASTERN LONG ISLAND. NO HYDROLOGIC IMPACTS ARE EXPECTED DUE TO ITS FROZEN STATE...AND LITTLE SUBSEQUENT MELTING OF ANY SNOW PACK AS LONG TERM HIGH TEMPS BARELY REACH THE LOWER 40S MAINLY IN URBAN/COASTAL SECTIONS DURING MID TO LATE WEEK.

&&

.TIDES/COASTAL FLOODING... WITH LOW PRESSURE RAPIDLY DEEPENING OFFSHORE THROUGH TONIGHT...THERE IS THE POTENTIAL FOR WIDESPREAD MINOR COASTAL FLOODING AND EVEN ISOLATED MODERATE COASTAL FLOODING TOWARDS WESTERN LONG ISLAND SOUND FOR THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY MONDAY MORNING.

GFS STORM SURGE GUIDANCE SHOWS ABOUT 2 TO 3 FT OF STORM SURGE ON AVERAGE FOR LATE TONIGHT INTO EARLY MONDAY. NOT ENOUGH CONFIDENCE TO ISSUE WATCH WITH ONLY ONE SPOT POTENTIALLY GETTING TO MODERATE COASTAL FLOODING...THE VERY STRONG OFFSHORE NORTHERLY FLOW...AND A LOWER ASTRONOMICAL CYCLE NEAR HALF MOON. THE UNCERTAINTY IS WITH HOW MUCH THE OFFSHORE WINDS WILL REDUCE THE WATER LEVEL AND RIGHT NOW GUIDANCE MAY HAVE TO BE UNDERCUT A LITTLE. BEST CHANCE FOR WATCH WOULD BE LONG ISLAND SOUND WITH THE GREATER SURGE VALUES THERE THAT ARE CLOSER TO 3 FT. THESE LOCATIONS ARE ALSO GREATER THAN OR EQUAL TO 1.5 FT ABOVE THE MAXIMUM ASTRONOMICAL TIDE WHEREAS THE LOCATIONS IN THE BAYS AND ALONG THE OCEAN ARE LESS THAN A FOOT ABOVE MAXIMUM ASTRONOMICAL TIDE.

WAVES ON SOUND MAY OVERWASH NORTH SHORE VULNERABLE AREAS. IF MORE GUIDANCE AGREEMENT OCCURS WITH ANY LOCATION GETTING TO MODERATE THRESHOLD...A COASTAL FLOOD WATCH MAYBE ISSUED.

&&

.OKX WATCHES/WARNINGS/ADVISORIES... CT...BLIZZARD WARNING UNTIL 6 PM EST MONDAY FOR CTZ007>012. WINTER STORM WARNING UNTIL 6 PM EST MONDAY FOR CTZ005-006. NY...BLIZZARD WARNING UNTIL 6 PM EST MONDAY FOR NYZ071>075-078>081- 176>179. WINTER STORM WARNING UNTIL 6 PM EST MONDAY FOR NYZ067>070. NJ...BLIZZARD WARNING UNTIL 6 PM EST MONDAY FOR NJZ002-004-006- 103>108. MARINE...STORM WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST MONDAY FOR ANZ330-335-338-340-345. STORM WARNING FROM NOON TODAY TO 6 AM EST MONDAY FOR ANZ350- 353-355. &&

$$ SYNOPSIS...JMC/GOODMAN NEAR TERM...JMC SHORT TERM...JMC LONG TERM...JMC/MAS AVIATION...JM/JST MARINE...JMC/GOODMAN/MAS HYDROLOGY...JMC TIDES/COASTAL FLOODING...JM

Final shift in storm; realization we’re dead meat. 5.5 hours before full force strike. Note there is an internet rumor that the MTA shifted from a winter weather Plan 1, in effect since before the weekend started, to a Plan 4 on Sunday afternoon.  Even at this point, eastern Long Island was expected to be hit harder than NYC.

I can recall a few times when similar storms veered the other way, causing much mockery of those who played it safe. Remember the wimpy snow day in NYC a year or two ago?

000 FXUS61 KOKX 261726 AFDOKX

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 1226 PM EST SUN DEC 26 2010

.SYNOPSIS... A DEVELOPING STORM OFF THE NORTH CAROLINA COAST WILL MOVE NORTHEAST TO JUST SOUTH OF LONG ISLAND TONIGHT...BRINGING BLIZZARD CONDITIONS LATE THIS AFTERNOON INTO MONDAY MORNING. THE STORM WILL MOVE INTO THE CANADIAN MARITIMES ON MONDAY. HIGH PRESSURE WILL RETURN FOR THE MIDDLE OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/... SOME IMPORTANT CHANGES FORTHCOMING WITH THIS UPDATE. BASED ON EARLIER THINKING...AND WITH 12Z GFS/NAM BOTH IN CLOSE PROXIMITY ON LOW TRACK AND QPF...HAVE BUMPED UP SNOW TOTALS AND ALSO EXPANDED BLIZZARD WARNINGS TO THE ENTIRE CWA. INTENSE MESOSCALE BANDING EXPECTED TO PIVOT INTO NYC METRO AND WESTERN/CENTRAL LONG ISLAND LATER TODAY/TONIGHT SHOULD DELIVER STORM TOTAL SNOWFALL OF 15-20 INCHES...LOCALLY AS MUCH AS 2 FEET. OTHER AREAS IN THE CWA SHOULD SEE 12-18 INCHES. WIND WILL BE A LIMITING FACTOR ON WHAT WOULD OTHERWISE HAVE BEEN EXCELLENT SNOW RATIOS OF 15-1 OR 20-1 GIVEN INTENSE LIFT AT IDEAL SNOW GROWTH TEMPERATURES ALOFT... WITH ROEBBER NEURAL NET ALGORITHM SUGGESTING GREATER LIKELIHOOD OF RATIOS UNDER 10-1...SO USED CLIMATOLOGICAL 11-1 RATIO INSTEAD AND SCALED DOWN WHERE TEMPS RISE ABOVE FREEZING. NAM/GFS ALSO IN CLOSER AGREEMENT ON MIXING BEING LIMITED TO THE SOUTH FORK OF EASTERN LONG ISLAND...SO WILL HAVE LOWER AMOUNTS MAINLY 6-12 INCHES THERE.

FROM EARLIER DISCUSSION...EXACTLY WHERE HEAVIEST SNOW WILL FALL LATER TODAY INTO TONIGHT MAY BE COMING MORE INTO FOCUS. THE 12Z NAM SHOWED ITS STRONGEST H7-8 LAYER FRONTOGENESIS DISPLACED ABOUT 30 MILES NW OF THE STRONGEST RADAR RETURNS OFF DELMARVA ATTM...NO SURPRISE THERE AS THIS OFTEN HAPPENS WITH INTENSE COASTAL STORMS. TAKING THE NAM OTHERWISE AS A PERFECT PROG AND FOLLOWING EVOLUTION OF ITS FRONTOGENETIC FORCING INDICATES THAT THE HEAVIEST SNOW WILL OCCUR OVER SOUTH CENTRAL CT INTO WESTERN SUFFOLK AND NASSAU COUNTIES ON LONG ISLAND..POSSIBLY A LITTLE FARTHER WEST INTO SOUTHWEST CT AND NYC IF YOU LOOK AT H7 FRONTOGENESIS ONLY. PER ABOVE HAVE INCREASED MAX TOTALS...AS THAT BANDING LOOKS TO SET UP THERE TOWARD EVENING AND REMAIN FOR A GOOD CHUNK OF THE NIGHT.

THE DEEP LOW WILL ALSO PRODUCE A POTENTIALLY DAMAGING WIND FIELD. BL WINDS IN THE GFS STILL CLOSE TO 60 KT OVER LONG ISLAND. NAM WIND FIELDS ARE WEAKER AT THE COAST BUT STRONGER INLAND. FOR THIS REASON HAVE BUMPED WIND GUSTS UP TO 45-60 MPH AND EXTENDED BLIZZARD WARNINGS TO ENTIRE CWA. LOCALLY HIGHER GUSTS POSSIBLE ACROSS EASTERN LI.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/... THE STORM WINDS DOWN MONDAY WITH STRONG WINDS CONTINUING. THE ACCUMULATING SNOW APPEARS IT WILL BE OVER BY 15Z ATTM. DRY WITH LESS WIND TUE.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...NO CHANGES...

NORTHWEST FLOW BEGINS TO DIMINISH ON TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION AND THE PRESSURE GRADIENT RELAXES. TUES NIGHT THROUGH THU SHOULD BE DRY CONDITIONS AND HIGH TEMPS RIGHT AROUND NORMAL...TOPPING OFF IN THE UPPER 30S AND LOWER 40S. GFS INDICATES A WARM FRONTAL APPROACH THU NIGHT-FRI WHILE ECMWF KEEPS THE FRONT WELL TO THE WEST...WILL TAKE THE MIDDLE GROUND AND FORECAST ONLY SLIGHT CHANCE POP FOR SOME LIGHT PCPN AT THAT TIME. SLIGHTLY WARMER ON FRI AND SAT WITH HIGHS IN THE LOWER AND MID 40S. PCPN CHANCES BEGIN TO INCREASE LATE SAT AS A SFC SYSTEM APPROACHES FROM THE OHIO VALLEY.

&&

.AVIATION /17Z SUNDAY THROUGH THURSDAY/... A MAJOR WINTER STORM WILL IMPACT THE TERMINALS THIS AFTERNOON THROUGH MONDAY WITH HEAVY SNOW AND HIGH WINDS.

LIGHT SNOW HAS MOVED ONTO LONG ISLAND...WITH MVFR VSBYS REPORTED AT KISP AND FLURRIES AT KJFK. THE LEADING EDGE OF SNOW WILL CONTINUE TO MOVE NORTH AND OVERSPREAD THE REGION OVER THE NEXT COUPLE OF HOURS. MEANWHILE...HEAVIER SNOW BANDS ARE DEVELOPING ABOUT 30 MILES OFFSHORE S OF LONG ISLAND. MOVED IFR VSBYS UP TO 18Z WITH 15Z TAF UPDATE. SNOW WILL CONTINUE TO INCREASE IN INTENSITY THIS AFTERNOON WITH SUB-IFR CONDITIONS LATE THIS AFTERNOON THROUGH TONIGHT.

MESOSCALE BANDING WILL BE LIKELY OVER THE NY METRO WITH 1+" PER HOUR ACCUMULATION RATES POSSIBLE AFTER 19Z AND MORE LIKELY BY 21Z.

SNOW TOTALS OF 11-15" EXPECTED.

NNE WINDS WITH GUSTS TO 20 KT HAVE DEVELOPED OVER SEVERAL TERMINALS. GUSTS WILL CONTINUE THIS AFTERNOON AND GRADUALLY INCREASE TO AROUND AND 30 KT LATE THIS AFTERNOON AND THEN BETWEEN 40 AND 50 KT FOR KISP...KBDR...AND KGON THIS EVENING. SOME OCCASIONALLY HIGHER GUSTS WILL BE POSSIBLE.

OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...

MON...MOSTLY LIGHT SNOW WITH NO ACCUMULATING SNOW ON MONDAY DAYTIME...BUT BLOWING SNOW IN NW 30 G 40 KT WND. CIGS GRADUALLY IMPROVING TO MVFR/VFR BY LATE MON MORNING. TUE...VFR...GUSTY NW WINDS. WED AND THU...VFR.

&&

.MARINE... ALL WATERS UPGRADED TO STORM. PEAK WINDS WILL BE AFTER DARK. STORM FORCE WINDS MAY NOT OCCUR OUTSIDE OF THE OCEAN UNTIL THE TONIGHT PERIOD...WITH MAINLY GALE FORCE WINDS LATE THIS AFTERNOON.

LOW WATER PROBLEMS ARE POSSIBLE AT THE TIMES OF LOW TIDE MON AFTERNOON AND NIGHT AFTER PASSAGE OF THE LOW.

THEREAFTER...GALES CONTINUE FROM MON INTO TUE...FOLLOWED BY GRADUALLY DIMINISHING WINDS TUE NIGHT.

&&

.HYDROLOGY... SNOW SUNDAY THROUGH MONDAY AFTERNOON WILL GENERALLY YIELD LIQUID EQUIVALENT AMOUNTS OF 1.25 TO 2.00 INCHES...HEAVIEST IN NYC METRO AND LONG ISLAND. NO HYDROLOGIC IMPACTS ARE EXPECTED DUE TO ITS FROZEN STATE...AND LITTLE SUBSEQUENT MELTING OF ANY SNOW PACK AS LONG TERM HIGH TEMPS BARELY REACH THE LOWER 40S MAINLY IN URBAN/COASTAL SECTIONS DURING MID TO LATE WEEK.

&&

.TIDES/COASTAL FLOODING... WITH LOW PRESSURE RAPIDLY DEEPENING OFFSHORE THROUGH TONIGHT...THERE IS THE POTENTIAL FOR WIDESPREAD MINOR COASTAL FLOODING AND EVEN ISOLATED MODERATE COASTAL FLOODING TOWARDS WESTERN LONG ISLAND SOUND FOR THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY MONDAY MORNING.

GFS STORM SURGE GUIDANCE SHOWS ABOUT 2 TO 3 FT OF STORM SURGE ON AVERAGE FOR LATE TONIGHT INTO EARLY MONDAY. A COASTAL FLOOD WATCH HAS BEEN ISSUED FOR ALL OF THE AREA SURROUNDING LONG ISLAND SOUND. DESPITE A LOWER ASTRONOMICAL CYCLE NEAR HALF MOON AND UNCERTAINTY IN THE MODEL GUIDANCE...IT IS PRUDENT TO ISSUE A WATCH ATTM WITH SOME GUIDANCE SUGGESTING 5 FT TIDAL DEPARTURES ON THE SOUND. THE MOST SUSCEPTIBLE AREAS ATTM ARE ALONG THE N SHORE OF LI AND INTO QUEENS DUE TO THE FCST NLY WIND DIRECTION. SMALL CHANGES IN THE TRACK HOWEVER WILL INFLUENCE WIND DIRECTION...AND ANY WWD TREND IN THE ACTUAL LOW WOULD FAVOR NE WINDS AND GREATER IMPACTS TO CT.

&&

.OKX WATCHES/WARNINGS/ADVISORIES... CT...COASTAL FLOOD WATCH FROM 11 PM EST THIS EVENING THROUGH LATE TONIGHT FOR CTZ009>012. BLIZZARD WARNING UNTIL 6 PM EST MONDAY FOR CTZ005>012. NY...COASTAL FLOOD WATCH FROM 11 PM EST THIS EVENING THROUGH LATE TONIGHT FOR NYZ071-073-078-079-176-177. BLIZZARD WARNING UNTIL 6 PM EST MONDAY FOR NYZ067>075-078>081- 176>179. NJ...BLIZZARD WARNING UNTIL 6 PM EST MONDAY FOR NJZ002-004-006- 103>108. MARINE...STORM WARNING FROM 4 PM THIS AFTERNOON TO 6 AM EST MONDAY FOR ANZ330-335-338-340-345. STORM WARNING UNTIL 6 AM EST MONDAY FOR ANZ350-353-355.

&&

$$

SYNOPSIS...GOODMAN NEAR TERM...GOODMAN SHORT TERM...GOODMAN/JMC LONG TERM...JMC/MAS AVIATION...KCS MARINE...GOODMAN/JMC/MAS HYDROLOGY...GOODMAN TIDES/COASTAL FLOODING...MURRAY