FXUS61 KOKX 090135
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
835 PM EST TUE DEC 8 2009
.SYNOPSIS...
HIGH PRESSURE SLIDES NORTHEAST TONIGHT INTO THE CANADIAN MARITIMES
TONIGHT. INTENSE LOW PRESSURE OVER THE CENTRAL PLAINS MOVES INTO
THE GREAT LAKES TOMORROW...WITH A SECONDARY LOW DEVELOPING OFF THE
NJ COAST. THIS LOW MOVES ACROSS LONG ISLAND AND RACES INTO NEW
ENGLAND BY TOMORROW EVENING. HIGH PRESSURE WILL RETURN FOR THE
REST OF THE WORK WEEK...BUT ANOTHER STORM COULD IMPACT THE AREA
THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
SKIES BECOMING OVERCAST THIS EVENING WITH WARM AIR ADVECTION ALOFT
STRENGTHENING AS A POTENTIALLY HIGH IMPACT SYSTEM MOVES UP OUT OF
THE CENTRAL PLAINS.
RADIATIONAL COOLING SHOULD BE SOMEWHAT LIMITED BY INCREASING CLOUD
COVER...BUT NOT ENOUGH TO PREVENT TEMPS FROM FALLING BELOW
FREEZING FOR THE INTERIOR LOWER HUDSON VALLEY AND CT.
WAA ALOFT INCREASES IN EARNEST LATE THIS EVENING AND EXPECT PRECIP
TO BEGIN MOVING IN AROUND MIDNIGHT OR SLIGHTLY AFTER. THIS IS
FASTER THAN THE OPERATIONAL MODELS...WHICH TEND TO BE TOO SLOW
WITH THE ONSET OF PRECIP IN STRONG WAA EVENTS.
PRECIP MAY START AS A BRIEF PERIOD OF SLEET/SNOW IN MANY PLACES
INCLUDING NYC...AS DEWPOINTS IN THE LOW TO MID 20S WOULD GIVE A
WET BULB TEMP IN THE LOW 30S. COASTAL SECTIONS WILL GO OVER TOO
RAIN ALMOST IMMEDIATELY HOWEVER. WINTRY WEATHER LASTS LONGER TO
THE NORTH.
SNOWFALL RATES AND AMOUNTS ARE VERY COMPLEX. LL JET INCREASES TO
70+ KTS ACROSS A 15 DEG C GRADIENT OVERNIGHT...INDICATING INTENSE
LIFT AND THE POTENTIAL FOR HEAVY PRECIP. IF THE COLD COLUMN IS
DEEP ENOUGH TO SUPPORT SNOW THROUGH 4-6AM...THE LIFT MAY BE STRONG
ENOUGH TO SUPPORT RATES OF 1-2 INCHES PER HOUR. GIVEN HOW STRONG
THE WARNING IS...DID NOT INCLUDE THESE TYPE OF ACCUMULATIONS IN
THE FORECAST...BUT IT SHOULD BE NOTED.
SO...THE WINTER WEATHER ADVISORY REMAINS AS IS. SOME OF THE DEEPER
VALLEYS IN ORANGE AND PASSAIC COUNTIES MAY SEE A BIT MORE
ICING...ESPECIALLY IF SFC TEMPS DIP A FEW DEGREES LOWER THAN
FORECAST THIS EVENING.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
STRONG WARMING CONTINUES INTO THE MORNING...AND ONCE THE SFC WARM
FRONT MATERIALIZES...THERE COULD BE A VERY RAPID CHANGEOVER TO ALL
RAIN. AGAIN...THIS MAY OCCUR A FEW HOURS PRIOR TO OR AFTER THE
CURRENT FORECAST...BUT THE TREND IS FOR A CHANGE TO ALL LIQUID.
TOTAL SNOWFALL OF UP TO 5 INCHES IN ORANGE/PASSAIC...BUT WOULD NOT
BE SURPRISED IF A FEW SPOTS SAW MORE.
ANOTHER ISSUE IS WIND SPEEDS. AS THE TEMP RISES ALOFT...IT WILL BE
TOUGH TO MIX DOWN STRONGER WINDS. HOWEVER...FOR A FEW HOURS PRIOR
TO THE PASSAGE OF THE WARM FRONT...THERE MAY BE ENOUGH INSTABILITY
TO GET ADVISORY LEVEL WINDS NEAR THE COAST. WIND ADVISORY HOISTED
TO ADDRESS THIS THREAT. THERE MAY ALSO BE ROUGH SURF/BEACH EROSION
PROBLEMS WEDNESDAY MORNING GIVEN STRONG EAST TO SOUTHEAST WINDS
AND 6 TO 9 FT NEAR SHORE BREAK.
PRECIP SHOULD WIND DOWN DURING WED AFTERNOON AS THE SECONDARY LOW
PASSES OVER LONG ISLAND. BOTH OPERATIONAL NAM AND GFS BRING DRY
AIR INTO THE REGION BY LATE AFTERNOON WEDNESDAY.
STRONGEST COLD AIR ADVECTION IS ABOUT 12 HOURS BEHIND THE
SYSTEM...SO TEMPS NOT EXPECTED TO DROP RIGHT AWAY.
TEMPS ALOFT PLUNGE THURSDAY...SO EXPECT A PRETTY FLAT TEMP TREND
DURING THE DAY...AND COLD TEMPS THURSDAY NIGHT.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE WILL BUILD INTO THE CWA BEHIND THE DEPARTING LOW....
AND REMAIN THROUGH SATURDAY NIGHT...PROVIDING FAIR AND DRY
CONDITIONS...BUT WITH GUSTY W WINDS CONTINUING THU INTO FRI.
IT WILL BE COOL...WITH HIGHS ONLY REACHING THE UPPER 30S AND
LOWER 40S...WITH OVERNIGHT LOWS FALLING INTO THE TEENS AND 20S.
AN AREA OF LOW PRESSURE MAY IMPACT THE CWA SAT NIGHT INTO
SUNDAY...AND THERE IS SOME DISAGREEMENT AMONG THE FORECAST MODELS
AS TO THE EXACT TRACK THIS LOW TAKE...AND JUST HOW CLOSE IT WILL
COME. FOR NOW WILL CARRY JUST SLIGHT CHANCE POP SAT NIGHT...AND
INCREASE TO CHANCE POP DURING SUNDAY. HIGH PRESSURE SHOULD RETURN
SUNDAY NIGHT INTO MON.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRESSURE RETREATS TO THE NORTHEAST TONIGHT AS STRENGTHENING
LOW PRESSURE MOVES FROM THE MID MISSISSIPPI RIVER VALLEY TO LAKE
MICHIGAN. A WEAKER SECONDARY LOW IS FORECAST TO DEVELOP ON A WARM
FRONT NEAR THE MID ATLANTIC COAST AND PASS OVER THE AREA ON
WEDNESDAY.
CONDS WILL DETERIORATE AFTER MIDNIGHT. PUSHED BACK ONSET OF PRECIP
2 HOURS BASED ON RADAR IMAGERY AND THE AMOUNT OF DRY AIR THAT MUST
BE OVERCOME. HOWEVER...PRECIP COULD START CLOSER TO 06Z. WILL WATCH AND
AMEND ACCORDINGLY. COULD HAVE AN HOUR OR TWO OF SLEET AT THE ONSET
(EXCEPT AT KSWF) DUE TO EVAPORATIVE COOLING...BUT IT WON'T LAST
LONG. TIMING OF IFR IS TRICKY BECAUSE OF THE STRONG WINDS AND
HEAVY PRECIP (TURBULENT MIXING)...BUT THE FLOW BEING E-SE SHOULD
CAUSE THEM TO OCCUR. THERE COULD EVEN BE ISOLD LIFR. GUSTS MAY
CEASE ALL-TOGETHER BETWEEN 17Z AND 22Z IF THERE IS A DISTINCT LOW
CENTER AT THE SFC...BUT THERE COULD JUST BE BAGGINESS IN THE
PRESSURE FIELD...SO LEFT THE GUSTS IN THROUGH THE DAY.
TIMING OF CHANGEOVER AT KHPN AND KSWF IS UNCERTAIN AND WILL BE
DEPENDANT ON WHEN THE WARMER AIR ALOFT CAN OVERCOME THE HEAVY
PRECIP. FZRA ALSO WITHIN THE REALM OF POSSIBILITIES AT KSWF IF
COLD AIR END UP TRAPPED AT THE SFC...HOWEVER A CHANGEOVER TO ALL
RAIN IS EXPECTED BY MID MORNING.
HAVE KEPT MVFR CONDS AT NYC TERMS UNTIL 23Z...BUT THIS MAY BE A
FEW HOURS TOO LONG.
OUTLOOK 00Z THURSDAY THROUGH SUNDAY...
WEDNESDAY NIGHT...VFR WITH GUSTY WSW WINDS.
THURSDAY-FRIDAY...VFR WITH GUSTY W WINDS.
FRIDAY NIGHT...VFR WITH DIMINISHING WINDS.
SATURDAY...VFR.
SUNDAY...SUB VFR POSSIBLE.
&&
.MARINE...
PRESSURE GRADIENT RAPIDLY STRENGTHENS OVERNIGHT AHEAD OF A COMPLEX
LOW PRESSURE SYSTEM TRACKING NE TOWARDS THE GREAT LAKES AND HIGH
PRESSURE SLOWLY SLIDING NE. EXPECTING EASTERLY WINDS ON ALL WATERS
TO INCREASE TO GALE LATE TONIGHT AHEAD OF ASSOC WARM FRONT AND
CONTINUE THROUGH AROUND 18Z AT WHICH TIME LLJ LIFTS N. EXPECTING
SEAS ON THE OCEAN TO RAPIDLY INCREASE TO 14 TO 17 FT IN RESPONSE.
WINDS WILL LIKELY FALL TO SCA LEVEL FOR A 6 TO 9 HR PERIOD WED
AFTERNOON INTO EARLY WED EVE AS WARM FRONT MOVES THROUGH...BEFORE
PICKING UP AGAIN TO GALE WED NIGHT ON ALL WATERS IN WAKE OF COLD
FRONT WITH STRONG CAA. GALES MAY CONTINUE INTO FRI...ESPECIALLY
OCEAN WATERS WITH PROLONGED PERIOD OF CAA AND TIGHT WESTERLY
GRADIENT IN WAKE OF SLOWLY DEPARTING LOW AND STRONG HIGH PRESSURE
OVER TENNESSEE VALLEY. SEAS REMAINING HIGH...PARTICULARLY EASTERN
WATERS.
RELATIVELY QUIET CONDITIONS ON SATURDAY AS HIGH PRESSURE BUILD IN.
THEN WINDS AND SEAS MAY BUILD AGAIN SATURDAY NIGHT AND SUNDAY WITH
THE POTENTIAL OF A COASTAL STORM AFFECTING THE REGION.
&&
.HYDROLOGY...
2 TO 2.5 INCHES LIQUID/LIQUID EQUIVALENT PRECIPITATION IS FORECAST FOR
TUESDAY NIGHT THROUGH WEDNESDAY...WITH LOCALLY HIGHER AMOUNTS
POSSIBLE. WHILE THE MAIN IMPACT IS EXPECTED TO BE URBAN/SMALL
STREAM FLOODING...IT COULD BE WIDESPREAD ENOUGH TO HAVE
SIGNIFICANT IMPACT ON THE MORNING RUSH. A FLASH FLOOD WATCH HAS
BEEN ISSUED.
QPF AMOUNTS SHOULD BE MAXIMIZED DURING THE 5AM TO 11AM TIMEFRAME.
0.5 TO 1.0 INCH PER HOUR RATES ARE POSSIBLE DURING THIS PERIOD.
&&
.TIDES/COASTAL FLOODING...
MAIN CONCERN FOR COASTAL FLOODING WILL BE THE TIMES OF HIGH TIDE IN
WESTERN LONG ISLAND SOUND EARLY WED MORNING WHERE AROUND 2 FT
DEPARTURES ARE NEEDED FOR MINOR COASTAL FLOODING. WINDS AND PRESSURE
FALLS WILL JUST BE GETTING GOING AT THAT TIME...SO THINKING IS THAT
WE WILL GET CLOSE TO MINOR COASTAL FLOODING LEVELS...BUT FALLING
SHORT FOR THE MOST PART. ISOLATED MINOR IS POSSIBLE...BUT NOT ENOUGH
CERTAINTY FOR ADVISORY.
WINDS ARE WEAKENING AND THEN TURNING SW FOR THE LATE
AFTERNOON/EVENING HIGH TIDES...SO NOT EXPECTING US TO REACH THE 2 TO
2 1/2 FT NEEDED FOR MINOR.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 4 AM TO 2 PM EST WEDNESDAY FOR CTZ009>012.
FLASH FLOOD WATCH FROM 6 AM EST WEDNESDAY THROUGH WEDNESDAY
AFTERNOON FOR CTZ005>012.
NY...WIND ADVISORY FROM 4 AM TO 2 PM EST WEDNESDAY FOR NYZ071>081.
FLASH FLOOD WATCH FROM 6 AM EST WEDNESDAY THROUGH WEDNESDAY
AFTERNOON FOR NYZ067>081.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
WEDNESDAY FOR NYZ067>070.
NJ...WIND ADVISORY FROM 4 AM TO 2 PM EST WEDNESDAY FOR NJZ006.
FLASH FLOOD WATCH FROM 6 AM EST WEDNESDAY THROUGH WEDNESDAY
AFTERNOON FOR NJZ002>006-011.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST
WEDNESDAY FOR NJZ002.
MARINE...GALE WARNING FROM 3 AM WEDNESDAY TO 6 AM EST THURSDAY FOR
ANZ330-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
HYDROLOGY...
TIDES/COASTAL FLOODING...
