FXUS61 KOKX 252332
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
632 PM EST FRI DEC 25 2009

.SYNOPSIS...
LOW PRESSURE MOVING NORTHEAST THROUGH THE SOUTHERN APPALACHIANS
WILL MOVE OFF THE US EAST COAST AND PASS NEAR THE REGION BY
SATURDAY NIGHT. WEAK HIGH PRESSURE RETURNS SUNDAY...AND IS
REINFORCED BY A STRONG ARCTIC COLD FRONT EARLY NEXT WEEK. COLD HIGH
PRESSURE BUILD IN FOR THE MID WEEK PERIOD. A STORM SYSTEM MAY
IMPACT THE AREA LATE IN THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
630 PM UPDATE...INITIAL BAND OF LIGHT RAIN AND SLEET HAS MOVED
INTO FAR WESTERN 1/4 OF CWA...MOVING SLOWLY NE AT 20 MPH. INCREASE
WARM ADVECTION IN ITS WAKE SHOULD HAVE PRECIP CONTINUE TO DEVELOP
IN ITS WAKE AND SPREAD NE ACROSS WESTERN 1/3RD OF REGION THROUGH 8
PM. TEMPS IN FZRA ADVISORY AREA CONTINUE TO RUN JUST ABOVE
FREEZING WITH DEWPOINTS IN THE UPPER 20S...EXPECTING THEM TO FALL
AT OR JUST BELOW FREEZING ONCE PRECIP BEGINS. HAVE SPED UP START
TIME OF ADVISORY ACROSS N.FAIRFIELD AND N NEW HAVEN TO 00Z WITH
PRECIP PROGGED TO REACH IN THIS AREA BETWEEN 1 AND 2Z.

OTHERWISE...BASED ON TEMPS AND DEWPOINTS ONLY EXPECTING PATCHY
FREEZING RAIN ACROSS HILLS OF UNION/ESSEX/E.PASSAIC/BERGEN AND
S.WESTCHESTER...SO HAVE ADDRESSED WITH SPS. LIKELY SAME PATCHY
SCENARIO PLAYS OUT ACROSS HILLS OF COASTAL CONNECTICUT LATER THIS
EVENING INTO TONIGHT. CITY/LONG ISLAND/IMMEDIATE COASTAL CONN
SHOULD HOLD MAINLY ABOVE FREEZING ONCE PRECIP STARTS.

PREVIOUS NEAR TERM... 
MASSIVE LOW PRESSURE OVER THE UPPER MIDWEST RETROGRADING WESTWARD
INTO THE DAKOTAS. SECONDARY...WEAKER LOW OVER THE CENTRAL
APPALACHIANS SPREADING PRECIPITATION NORTHWARD INTO THE MID-
ATLANTIC STATES.

HIGH PRESSURE OVER EASTERN CANADA MAINTAINING A NORTHEAST FLOW
OVER THE AREA WHICH WILL INCREASE AS THE LOW APPROACHES. 

PRECIP TYPE WILL BE THE MAIN CHALLENGE WITH THIS SYSTEM TONIGHT
INTO TOMORROW. WAA ALOFT IS WEAK AND THE BEST JET DYNAMICS ARE
FAR TO THE WEST...RESULTING IN A SLOW EASTWARD PROGRESSION OF
CATEGORICAL POP.

THE MAIN CHALLENGE TONIGHT IS WHETHER PRECIP OCCURS ACROSS THE
INTERIOR NE CT ZONES WHILE TEMPS REMAIN BELOW FREEZING. WHILE
THERE IS NOT 80 PERCENT CONFIDENCE IN THAT...THERE SHOULD BE
ENOUGH AREAS OF FREEZING DRIZZLE TO MAKE ROADWAYS SLICK. THEREFORE
THE FREEZING RAIN ADVISORY CONTINUES ACROSS THE NE CT ZONES.

TEMPS WILL FALL A BIT THIS EVENING WITH EVAP COOLING...THEN STAY
FAIRLY STEADY OVERNIGHT. HOWEVER WITH MANY AREAS LOOKING TO BE
RIGHT AROUND FREEZING...SOME ADJUSTMENT TO THE ADVISORY IS
POSSIBLE.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
COLD AIR DAMMING SIGNATURE LOOKS TO HOLD INTO THE MORNING
HOURS...WHICH MAKES THE CHANGEOVER TIMING VERY TRICKY. ENOUGH WARM
AIR SHOULD INFILTRATE BY MIDDAY TO HAVE ALL RAIN. 

AT THIS TIME...ONE HALF TO ABOUT AN INCH OF RAIN EXPECTED. WHILE
NUISANCE FLOODING IS EXPECTED TO BE THE MAIN THREAT...AREAS WITH
DEEP SNOWPACK...MAINLY EASTERN LONG ISLAND...MAY SEE SOME MORE
SIGNIFICANT FLOODING OF ROADWAYS. 

WINDS MAY APPROACH ADVISORY LEVELS AT TIMES SAT AFTERNOON THROUGH
SUNDAY WITH IMPRESSIVE 50-60KT LL JET...HOWEVER INVERSION SHOULD
KEEP STRONGEST WINDS FROM MIXING. GUSTS TO 45 MPH POSSIBLE..ESP
ALONG THE COAST.

TEMPS STAY STEADY OR RISE A BIT SAT NIGHT WITH ALL AREAS ABOVE
FREEZING. 

THE BACK EDGE OF THE PRECIP EXPECTED TO MOVE THROUGH EARLY SUNDAY
WITH WEAK HIGH PRESSURE ON ITS HEALS. TEMPS REMAIN AT OR ABOVE
NORMAL INTO MONDAY. A STRONG ARCTIC FRONT BARRELS THROUGH...WITH A
CHANCE OF SNOW SHOWERS/SQUALLS AND PLUMMETING TEMPERATURES INTO THE
EVENING.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
DEEP TROUGHING OVER THE REGION TO START THE PERIOD WITH WELL BELOW 
NORMAL TEMPS. ARCTIC COLD FRONT CROSSES THROUGH THE REGION MON NIGHT 
IN WAKE OF INITIAL COLD FRONT WITH CLIPPER SYSTEM. WINDS MAY BRIEFLY 
GUST CLOSE TO WIND ADVISORY WITH TEMPS FALLING INTO THE TEENS AND 
LOWER 20S AREAWIDE. WIND CHILLS FALLING INTO THE LOWER SINGLE 
DIGITS CITY/COAST AND SINGLE DIGITS BELOW ZERO INTERIOR. A FEW SNOW 
SHOWERS POSSIBLE BEHIND THE ARCTIC FRONT.

WINDY AND COLD TEMPS TUES WITH TEMPS LIKELY NOT GETTING OUT OF THE 
20S AREAWIDE.

HIGH PRESSURE BUILDS OVER THE REGION TUES NIGHT WITH GOOD 
RADIATIONAL COOLING CONDS LIKELY.

SLOW MODERATION THROUGH MID WEEK AS UPPER FLOW BECOMES MORE ZONAL 
AND HIGH PRESSURE SLIDES OFFSHORE...BUT STILL BELOW SEASONABLE. THEN 
WILL HAVE TO KEEP AN EYE ON POSSIBLE PHASING OF NORTHERN AND 
SOUTHERN STREAM ENERGY ACROSS THE CENTRAL US ON THURS...WHICH WOULD 
HAVE IMPLICATIONS OF A POSSIBLE COASTAL STORM TO END THE WEEK.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE SLOWLY RETREATS NORTHEAST AS LOW PRESSURE DEVELOPS
OVER EASTERN NORTH CAROLINA AND VIRGINIA INTO SATURDAY.

MVFR STRATUS EXPECTED AT ALL TERMINALS THROUGH 20Z EXCEPT KSWF
WHERE LIFR CIGS ARE BEING OBSERVED. AFTER 20Z...CIGS WILL GRADUALLY LOWER
TO IFR...AND REMAIN IFR THROUGH THE REMAINDER OF THE TAF PERIOD.

RA...FZRA KSWF...DEVELOPS FROM SW TO NE STARTING NEAR
00Z...AND BECOMES STEADIER OVERNIGHT.

NE WINDS BECOME ENE AND SLOWLY INCREASE THROUGH TONIGHT.

CONDITIONS ARE NOT EXPECTED TO CHANGE MUCH THROUGHOUT THE DAY
SATURDAY.

OUTLOOK 18Z SATURDAY THROUGH TUESDAY...

SATURDAY AFTERNOON/NIGHT...IFR WITH RA.

SUNDAY AND SUNDAY NIGHT...RAIN COMES TO AN END FROM W TO E SUNDAY
WITH WIND SHIFT TO W. BECOMING VFR BY SUNDAY EVENING...WITH GUSTY
W WINDS DEVELOPING.

MONDAY AND MONDAY NIGHT...CHANCE SHSN WITH ARCTIC COLD FRONT...WITH
GUSTY WINDS BEHIND FRONT. POSSIBLE LOW PRESSURE DEVELOPMENT OFF
THE COAST WOULD RESULT IN SN CHANCES DEPENDING ON TRACK.

TUESDAY...VFR WITH GUSTY NW WINDS.

&&

.MARINE...
A BIT OF UNCERTAINTY AS TO WHETHER NY HARBOR AND WESTERN LI SOUND
WILL REACH GALE FORCE WINDS. STRONGEST WINDS ALOFT SHOULD HAVE
TROUBLE MIXING AND MAY NOT REACH MORE THAN 30 KTS ON THESE WATERS.
REMAINING WATERS A BETTER BET WITH BETTER DYNAMICS ALOFT. WILL
DECIDE ABOUT UPGRADING THE GALE WATCH TONIGHT. 

WINDS SHOULD BUILD SEAS TO 9 TO 14 FT ON THE OCEAN...HIGHEST
EASTERN ZONES...AND 3 TO 6 FT ON THE SOUND.

SLOW DECREASE IN WAVE HEIGHT ON THE OCEAN SUNDAY MAY RESULT IN SCA
CONDITIONS. 

INCREASING W WINDS SUN NIGHT-MONDAY BECOMING NW LATE MONDAY AND INTO 
TUESDAY BEHIND AN ARCTIC FRONT. GALE CONDS LIKELY ON THE OCEAN
WATERS AND POSSIBLE ALL WATERS MON NIGHT IN WAKE OF CLIPPER
SYSTEM AND ARCTIC FRONT WITH GRADUALLY IMPROVING CONDS TUES/TUES
NIGHT AS HIGH PRESSURE BUILDS INTO THE REGION. SUB SCA CONDS
EXPECTED ON WED AS HIGH PRESSURE BUILDS OVER THE REGION.

&&

.HYDROLOGY...
POTENTIAL EXISTS FOR AROUND AN INCH OF LIQUID EQUIVALENT 
QPF...MAINLY FROM LATE TONIGHT THROUGH SUNDAY MORNING. THIS 
POTENTIAL QPF FALLS ON TOP OF SNOW PACK WITH A WATER EQUIVALENT 
RANGING FROM 1/2 TO 1 INCH FROM NYC NORTH AND WEST TO UP TO 3 INCHES 
OVER EASTERN LI AND SE CT. THE COMBINATION OF THE SNOW PACK AND 
MODERATE RAIN WILL LIKELY LEAD TO URBAN FLOODING. RIVER AND STREAM 
FLOODING NORTH AND WEST OF NYC IS LESS LIKELY TO OCCUR DUE TO LESS 
OF A SNOW PACK. SOME ICING EXPECTED AS WELL NORTH AND WEST.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...FREEZING RAIN ADVISORY FROM 10 PM THIS EVENING TO NOON EST 
     SATURDAY FOR CTZ007-008.
     FREEZING RAIN ADVISORY UNTIL NOON EST SATURDAY FOR CTZ005-006.
NY...FREEZING RAIN ADVISORY UNTIL NOON EST SATURDAY FOR NYZ067>070.
NJ...FREEZING RAIN ADVISORY UNTIL NOON EST SATURDAY FOR NJZ002.
MARINE...GALE WATCH FROM 6 AM EST SATURDAY THROUGH SATURDAY AFTERNOON 
     FOR ANZ335-338-345.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ335-338-
     345.
     GALE WARNING UNTIL 6 PM EST SATURDAY FOR ANZ330-340-350-353-
     355.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...BC
MARINE...
HYDROLOGY...