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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 100523
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1223 AM EST WED FEB 10 2010

.SYNOPSIS...
COMPLEX LOW PRESSURE...WITH MULTIPLE CENTERS OVER THE OHIO VALLEY
AND ALONG THE SOUTHEAST COAST...WILL COMBINE INTO A MAJOR WINTER
STORM OFF THE MID ATLANTIC COAST LATE TONIGHT INTO WEDNESDAY
NIGHT...BRINGING SIGNIFICANT SNOWFALL TO OUR REGION. AN UPPER LEVEL
DISTURBANCE MAY TOUGH OFF A FEW INLAND SNOW SHOWERS ON
FRIDAY...OTHERWISE HIGH PRESSURE WILL FOLLOW FOR THE END OF THE
WEEK AND INTO THE WEEKEND. AN ALBERTA CLIPPER LOW PRESSURE SYSTEM
MAY BRING SOME LIGHT SNOW ON MONDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
-- Changed Discussion --
SNOW CONTINUES TO SPREAD NORTH AND EAST OVERNIGHT...SO UPPED POPS
ACROSS THE AREA. WITH DRY AIR AT THE LOWER LEVELS TEMPERATURES
HAVE COOLED WITH THE ONSET OF PRECIPITATION...AND WAS FALLING AS
ALL SNOW.

MORNING COMMUTE FOR THOSE VENTURING OUT WILL BE HAZARDOUS...WITH
2-4 INCHES OF ACCUMULATION POSSIBLE IN NYC METRO BY DAYBREAK...AND
1-2 INCHES MOST OTHER PLACES EXCEPT PERHAPS SOUTHEAST CT.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/...
DEEP CLOSED MID AND UPPER LEVEL LOW BARRELS ACROSS OHIO VALLEY TO A
POINT SOUTH OF CWA. THE INCIPIENT SURFACE LOW DESTINED TO BECOME
THE MAJOR WINTER STORM IS ALONG THE SOUTH CAROLINA COAST
ATTM...AND WILL TRACK NE CLOSE TO THE 40N/70W BENCHMARK...WHILE
STRONG WARM ADVECTION ALOFT NORTH OF THE CENTER...OTHERWISE KNOWN
AS A TROWAL...CAUSES DEVELOPMENT OF A SECOND CENTER NOT TOO FAR
OFF THE NJ COAST PER NAM/ECMWF. THERE IS SOME CONCERN THAT THIS
TROWAL/BENT-BACK WARM FRONT...OFTEN A FEATURE OF INTENSE OCEANIC
STORMS...COULD BRING IN WARM ENOUGH AIR ALOFT TO CAUSE A MIX WITH
SLEET ALONG/EAST OF THE I-95 CORRIDOR PER 12Z NAM...A MODEL WHICH
HAS TO BE RESPECTED IN THE NEAR TERM WITH ITS HANDLING OF INTENSE
COASTAL STORMS. DID NOT PLAY THIS HAND TOO MUCH WITH ECMWF
SHOWING SIMILAR DEVELOPMENT YET REMAINING COLDER AND A LITTLE
FATHER SOUTH...BUT IN ANY CASE THE ONSHORE FLOW COULD CAUSE A MIX
WITH RAIN ALONG THE SOUTH SHORE AND EAST END OF LONG
ISLAND...POSSIBLY COASTAL SE CT. PER GOOD MODEL CONSENSUS BEST
BANDING FEATURES WITH THE STORM LOOK TO BE ACROSS THE SOUTHERN
HALF OF THE AREA...WHERE SNOWFALL RATES OF AT LEAST 1-2
INCHES/HOUR ARE POSSIBLE DURING THE DAY ON WED...AND TOTAL
ACCUMULATIONS OF 10-16 INCHES OUTSIDE OF WHERE ANY MIXING WITH
RAIN TAKES PLACE. FARTHER NORTH/EAST...LESSER QPF AND/OR MIXING
WITH RAIN SHOULD HOLD ACCUMULATIONS DOWN A LITTLE...WITH 8-12
INCHES EXPECTED.

WINDS WILL INCREASE DURING THE DAY ON WED...ESPECIALLY BY
AFTERNOON AND IN COASTAL SECTIONS AS THE LOW DEEPENS. SINCE THE
SNOW WILL MORE LIKELY BE OF THE HEAVY WET VARIETY...AM NOT
CONFIDENT THAT WE WILL SEE WHITEOUT CONDITIONS OF LONG ENOUGH
DURATION TO WARRANT A BLIZZARD WARNING ATTM. WILL CLOSELY MONITOR
AND HANDLE MORE AS A SHORTER FUSED WARNING IF CONFIDENCE IN TRUE
BLIZZARD CONDITIONS INCREASES. AT ANY RATE...BLOWING/DRIFTING SNOW
EXPECTED DURING WED AFTERNOON...LASTING INTO AT LEAST THU MORNING
AFTER PRECIPITATION ENDS LATE WED NIGHT.

THE STRONG LOW PASSES WELL TO THE EAST...LEAVING DEEP NW FLOW IN ITS
WAKE. A CHILLY AND GUSTY THURSDAY IS EXPECTED.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
THE EXTENDED PERIOD WILL CONTINUE WITH A LONG WAVE TROUGH ACROSS THE
EASTERN UNITED STATES. SHORTWAVES ROTATE THROUGH THE UPPER
FLOW...WITH A CLIPPER SYSTEM PASSING JUST SOUTH OF THE REGION SUNDAY
NIGHT INTO MONDAY. SO...WILL SEE CHANCES FOR SOME SNOW
SHOWERS...MAINLY INLAND...WITH A CHANCE OF LIGHT SNOW WITH THE
CLIPPER.

A NORTHWEST TO WEST FLOW ALSO PREDOMINATES THROUGH THE PERIOD WITH
GUSTY WINDS AT TIMES. TEMPERATURES ALSO REMAIN BELOW NORMAL THROUGH
THE PERIOD WITH THE EASTERN TROUGH IN PLACE AND NORTHERLY FLOW.

GENERALLY FOLLOWED ECMWF AND HPC GUIDANCE.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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LOW PRES DEVELOPING OVER THE CAROLINAS WILL INTENSIFY AS
IT TRACKS NORTH TONIGHT AND WED MORNING...THEN OUT TO SEA WED AFTN
AND EVE.

CONDS QUICKLY DETERIORATE TO IFR OR LOWER ALL TERMINALS THROUGH 08Z
WITH HIGH CONFIDENCE THAT THIS PREVAILS FOR THE NEXT 12-18 HOURS.
STILL HAVE THE POTENTIAL FOR SLEET TO MIX IN AT COASTAL TERMINALS
WED MORNING...SO HAVE NOT REMOVED IT IN THE 06Z TAFS. THINK IT WILL BE
BRIEF SO CUT IT DOWN TO A 3 HR WINDOW. MAY BE TOO OPTIMISTIC ON
IMPROVING CONDS BETWEEN 00Z AND 03Z.

NE WINDS INCREASE THROUGHOUT THE DAY WED. POTENTIAL EXISTS FOR GUSTS
TO REACH 35 KT AT COASTAL TERMINALS LATE MORNING/EARLY AFTN.

EXPECTED SNOWFALL TOTALS...
JFK/LGA/EWR/TEB/ISP - 10-14"
BDR/GON/SWF - 8-12"
HEAVIEST RATES EXPECTED BETWEEN 12Z AND 16Z WHERE 2" PER HOUR IS
POSSIBLE.

OUTLOOK 06Z THU THROUGH SUN...
WED NIGHT...VFR RETURNS AFTER MIDNIGHT WITH -SN ENDING. GUSTY NW WINDS.
THU-SUN...VFR. GUSTY NW WINDS EACH DAY...SUBSIDING AT NIGHT.
-- End Changed Discussion --

&&

.MARINE...
WITH SNOW MOVING INTO THE FORECAST WATERS FROM THE SOUTH AND WEST
HAVE INCREASED POPS. WINDS AND SEAS STILL ON TRACK.

LOW PRES CONTINUES TO DEEPEN OFF THE CAROLINA COAST...AND WILL
RAPIDLY INTENSIFY OVERNIGHT THRU WED AS IT TRACKS NE...JUST SOUTH
OF LONG ISLAND. E/NE WINDS INCREASE TO GALE FORCE ALL WATERS WED
MORNING INTO EARLY AFTERNOON...AND STORM FORCE ACROSS THE OCEAN
WATERS. THESE WINDS ARE EXPECTED TO CONTINUE AT THIS MAGNITUDE
THROUGH THE EVENING WHILE BACKING N/NW...THEN GRADUALLY WEAKEN
THROUGH THE DAY THURSDAY AS LOW PRESSURE SLOWLY PULLS AWAY. 50 TO
55 KT GUSTS ARE POSSIBLE ON THE OCEAN. SEAS EXPECTED TO BUILD TO
12 TO 16 FT ON THE OCEAN AND 4 TO 8 FT ON THE SOUND LATE
WED...CONTINUING INTO WED NIGHT. HAVE GONE 3 TO 5 FT ABOVE
GUIDANCE BASED ON LOW WNA BIAS WITH THESE INTENSE SYSTEMS.

GALES GRADUALLY DIMINISH TO SCA CRITERIA BY THU AFTERNOON. GUSTY
NW WINDS WITH SCA CONDITIONS LIKELY THROUGH THU NIGHT.

FRI THROUGH SUNDAY COULD SEE SMALL CRAFT CONDITIONS MUCH OF THE
TIME...ESPECIALLY ON THE OCEAN WATERS WHERE WIND GUSTS AND/OR SEAS
WILL BE ABOVE SMALL CRAFT LEVELS. GENERALLY A NORTHWEST TO WEST FLOW
WILL PREDOMINATE. A CLIPPER SYSTEM MOVES SOUTH OF THE WATERS SUNDAY
NIGHT INTO MON WITH A CHANCE OF SOME LIGHT SNOW.

&&

.HYDROLOGY...
SIGNIFICANT QPF EXPECTED BEGINNING TONIGHT THROUGH WEDNESDAY WITH
A COASTAL STORM. LIQUID EQUIVALENT QPF CALLS FOR 0.75 INCH NORTH
AND 1-1.5 INCHES NEAR THE COAST...PREDOMINANTLY SNOW. NO FLOODING
ISSUES EXPECTED...WITH MUCH OF THE MELTING RE-FREEZING IN THE SNOW
PACK AS TEMPS REMAIN BELOW NORMAL FOR AT LEAST THE NEXT WEEK.

&&

.TIDES/COASTAL FLOODING...
BASED ON THE LATEST FORECAST...THE STRONGEST WINDS AND WAVES WILL
OCCUR WED AFTERNOON THROUGH WED EVENING BEFORE DIMINISHING BY THU
MORNING. THE BEST CHANCE FOR MINOR COASTAL FLOODING WILL BE DURING
THE WED EVE HIGH TIDE...WHEN FOR MODERATE COASTAL FLOODING...3.5 TO
4 FT DEPARTURES ARE NEEDED...WHILE 2.5 TO 3 FT DEPARTURES ARE NEEDED
FOR MINOR COASTAL FLOODING. POSITIVE TIDAL DEPARTURES OF 4 TO 5 FT
MAY BE NOTED DURING THE TIMES OF LOW TIDE WED AFTERNOON WHEN LOW
PRESSURE IS RAPIDLY DEEPENING...BUT THESE DEPARTURES ARE EXPECTED TO
FALL TO 3 FT AS TIDES APPROACH ASTRONOMICAL HIGHS AND WINDS ARE
SHIFTING TO THE N/NW. THIS SHOULD LIMIT COASTAL FLOODING TO MINOR
LEVELS. HIGH WAVE ACTION ON THE NORTH FACING SHORES OF LI SOUND WILL
LIKELY EXACERBATE THE MINOR FLOODING. WILL HOLD OFF ON A LATE 2ND
PERIOD ADVISORY TO LET SUBSEQUENT SHIFT MONITOR DEVELOPMENT OF LOW
PRESSURE.

TIDAL DEPARTURES OF 2 TO 2 1/2 FT ARE NEEDED FOR MINOR AND 3 TO 3
1/2 FT FOR MODERATE COASTAL FLOODING EARLY THU MORNING. MINOR
COASTAL FLOODING IS POSSIBLE THURS MORN ON THE SOUTH SHORE BAYS DUE
TO HIGH WAVE ACTION PREVENTING DRAINAGE.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR CTZ005-006-
     009-010.
     WINTER STORM WARNING FROM 4 AM EARLY THIS MORNING TO 6 AM EST
     THURSDAY FOR CTZ007-008-011-012.
NY...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NYZ067>081.
NJ...WINTER STORM WARNING UNTIL 6 AM EST THURSDAY FOR NJZ002>006-
     011.
MARINE...GALE WARNING FROM 6 AM THIS MORNING TO 6 AM EST THURSDAY FOR
     ANZ330-335-338-340-345.
     STORM WARNING FROM 6 AM THIS MORNING TO 6 AM EST THURSDAY FOR
     ANZ350-353-355.
-- End Changed Discussion --

&&

$$