FXUS61 KOKX 251153
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
653 AM EST FRI DEC 25 2009
.SYNOPSIS...
CANADIAN HIGH PRESSURE SLOWLY GIVES WAY TO DEVELOPING LOW PRESSURE
ALONG A FRONTAL BOUNDARY TONIGHT AND SATURDAY. THIS LOW AND
ASSOCIATED FRONT PASSES TO THE NORTHEAST LATE THIS
WEEKEND...FOLLOWED BY AN ARCTIC COLD FRONT EARLY NEXT WEEK. HIGH
PRESSURE BUILD IN FOR THE MID WEEK PERIOD. A STORM SYSTEM WILL
APPROACH FROM THE SOUTHEASTERN UNITED STATES ON THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WATER VAPOR IMAGERY SHOWS CLOSED LOW PIVOTING BACK TO THE WEST AS
LARGE CLOSED LOW GETS ORGANIZED OVER THE MID WEST. AS THIS LOW
GATHERS STRENGTH...RIDGE BUILDS OVER THE EASTERN SEABOARD TODAY.
SURFACE HIGH PRESSURE MOVES EAST ACROSS SOUTHEAST CANADA. WINDS
TURNING TO THE NORTHEAST...SATURATING LOW LEVELS AND DAMMING COLD
AIR ACROSS THE NORTHEAST. ANY STRATUS MAY HAVE A TOUGH TIME
BURNING OFF TODAY...THEN MID AND UPPER LEVEL CLOUDS FINALLY
PENETRATE THE RIDGE. THIS SHOULD TRANSLATE TO PLENTY OF CLOUD
COVER THROUGH THE DAY. TEMPS STRUGGLE THROUGH THE 30S...WITH
INTERIOR BARELY GETTING ABOVE FREEZING.
PRECIPITATION OUT AHEAD OF THIS MID WEST STORM AND DEVELOPING LOW
PRESSURE OVER MID ATLANTIC COAST ATTEMPTS TO MOVE IN VERY LATE IN THE
DAY. SOME WINTRY PRECIP THE RESULT AS TEMPS BEGIN TO DROP BELOW
FREEZING ONCE AGAIN. PLENTY OF WAA ALOFT TO SUPPORT MAINLY LIQUID
PRECIP. AS SUCH...FREEZING RAIN THE MAIN THREAT ACROSS INTERIOR
PORTIONS OF NEW JERSEY AND THE LOWER HUDSON VALLEY LATE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
AS SFC LOW AND FRONTAL BOUNDARY APPROACH...RAIN WILL MOVE IN...BUT
NOT MAKE A LOT OF EASTWARD PROGRESS AS RIDGING HANGS TOUGH...AND
THIS BASICALLY OUT RUNS SUPPORT ALOFT. WILL CONTINUE HIGHER POPS
WEST TO LOWER POPS EAST. BECAUSE OF THIS...WILL ISSUE BUT KEEP
WINTER WX HEADLINES CONFINED TO LOWER HUDSON VALLEY...WESTERN PASSAIC
NJ AND INTO FAIRFIELD COUNTY CT...BUT NO FURTHER EAST. CANNOT ISSUE
ADVISORIES WITH CHANCE POPS.
AS MENTIONED IN NEAR TERM SECTION...COLD AIR DAMMING AND
EAST/NORTHEAST FLOW WILL KEEP TEMPS BELOW FREEZING ACROSS THE
ADVISORY AREA. EXPECT ICING...MAYBE UP TO A QUARTER INCH OR SO
THROUGH TONIGHT. COULD SEE GREATER THAN A QUARTER INCH WELL UP IN
ORANGE COUNTY WHERE TEMPS TYPICALLY REMAIN COLD IN DAMMING EVENTS
FOR LONGER DURATION FROZEN TYPE PRECIP (IN SPITE OF MOS). WILL RUN
ADVISORIES INTO SATURDAY MORNING FOR NOW...BUT ORANGE COUNTY COULD
GO LONGER. SFC TEMP FORECASTS THE KEY HERE...AND LEANED TOWARD
MOS...BUT CUT A DEGREE OR TWO HERE AND THERE AS MOS HAS A TENDENCY
TO WARM THINGS TOO QUICKLY IN THESE DAMMING SITUATIONS. COUNTIES
JUST OUTSIDE OF THE ADVISORY AREA MAY NOT BE OUT OF THE WOODS.
WILL MENTION POTENTIAL FOR AT LEAST SOME ICING POTENTIAL FOR
COUNTIES BORDERING ADVISORY AREA.
PRECIP MOVES THROUGH SATURDAY NIGHT AS THE LOW/FRONT PIVOT TO THE
NORTH AND EAST. EVENTUALLY CLOSED LOW WEAKENS AS IT FINALLY GETS
KICKED OUT TO THE EAST. SUNDAY SHOULD BE MAINLY DRY...THEN
INSTABILITY SHOWERS/SNOW SHOWERS MOVE IN FROM THE WEST WITH THE
APPROACH OF THE LOW/SFC TROUGH.
TEMPS SHOULD CONTINUE TO AVERAGE ABOVE NORMAL SAT THROUGH SUNDAY
IN WAA PATTERN. AGAIN...INTERIOR LOCATIONS WILL TAKE SOMETIME TO
SCOUR OUT THE COLD AIR...BUT EAST TO SOUTHEAST FLOW EVENTUALLY
WARMS TEMPS ALL LOCALES SAT NIGHT...THEN IN WEST FLOW SUNDAY.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE LONG TERM IS CLASSIFIED AS A RETURN TO WINTER. WEAK CAA SUNDAY
NIGHT INTO MONDAY EVIDENT AS UPPER TROUGH MOVES ON BY..KICKING OFF
RAIN/SNOW SHOWERS. THEN REINFORCING SHOT OF COLD AIR MOVES IN LATER
MONDAY AND MONDAY NIGHT. TUESDAY LOOKS WINDY AND QUITE COLD AS H8
TEMPS FALL TO -16C TO -20C...ESPECIALLY INTERIOR.
BLENDED COLDER MEX NUMBERS WITH GMOS TO GET TEMPS INTO THE 20S
TUESDAY. HIGH PRESSURE BUILDS MID WEEK...THEN NEED TO KEEP AN EYE ON
THURSDAY FOR POSSIBLE COASTAL STORM.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE BUILDS DOWN FROM QUEBEC THIS MORNING...THEN SLOWLY
RETREATS NORTHEAST AS LOW PRESSURE DEVELOPS OVER EASTERN NORTH
CAROLINA AND VIRGINIA INTO SATURDAY.
MVFR STRATUS OVER ALL TERMINALS EXCEPT KSWF (VLIFR) AND KGON (IN
AND OUT FOR NOW). EXPECT LITTLE CHANGE IN WAY OF CEILINGS
TODAY...EXCEPT STRATUS SHOULD BECOME PREVAILING AT KGON BY MID
MORNING...AND KSWF SHOULD LIFT TO MVFR BY EARLY AFTERNOON (HIGH
CONFIDENCE IN KGON AND MODERATE CONFIDENCE IN CEILING LIFTING AT
KSWF). RA (FZRA KSWF...POSSIBLY MIXED WITH PL IN THE FIRST FEW
HOURS KTEB/KHPN - NOT CONFIDENT ENOUGH TO PUT IN TAF) DEVELOPS
FROM SW TO NE STARTING LATE THIS AFTERNOON...AND GETTING TO KGON
AROUND MIDNIGHT. CONDITIONS SHOULD GO TO IFR IN THE PRE-DAWN HOURS
(EXCEPT KGON).
NE WINDS BECOME ENE AND SLOWLY INCREASE THROUGH TONIGHT.
OUTLOOK 12Z SATURDAY THROUGH TUESDAY...
SATURDAY-SATURDAY NIGHT...IFR WITH RA (FZRA KSWF THROUGH AROUND
MIDDAY SATURDAY). LLWS SATURDAY...TRANSITIONING TO COMPRESSION
SATURDAY NIGHT (FLOW BECOMES UNI-DIRECTIONAL).
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...
NE FLOW WILL GRADUALLY STRENGTHEN TODAY...BUILDING SEAS ON THE
COASTAL OCEAN ZONES TO 3 TO 5 FT...SO WILL CONTINUE SCA FOR
HAZARDOUS SEAS THERE FOR TODAY.
E WINDS CONTINUE TO INCREASE TONIGHT DUE TO INCREASING GRADIENT
BETWEEN HIGH TO THE NE AND DEVELOPING LOW OVER EASTERN VA/NC...WITH
GUSTS TO GALE FORCE AFTER MIDNIGHT COASTAL OCEAN ZONES AND EASTERN
SOUND/BAYS...SO HAVE HOISTED A GALE WARNING FOR THOSE WATERS
TONIGHT/SATURDAY WITH A SMALL CRAFT ADVISORY REMAINDER OF WATERS.
WESTERN SOUND/BAYS/HARBOR WILL LIKELY SEE GALE GUSTS ON SATURDAY
(AND COULD SEE SOME OCCASIONAL GUST TO GALE FORCE TONIGHT) SO HAVE
PUT A GALE WATCH FOR THEN (NOT QUITE CONFIDENT ENOUGH TO PUT UP A
GALE WARNING AT THIS TIME). EXPECT SEAS TO BUILD TO 8-12 FT SATURDAY
ON THE OCEAN AND 3 TO 5 FT ON THE SOUND.
WINDS BACK TO THE SE SATURDAY NIGHT AND CONTINUE TO BE GUSTY WITH
GALE FORCE GUSTS LIKELY ON ALL WATERS...A LITTLE EARLY TO HAVE GALE
WARNING OUT THAT FAR...BUT WOULD EXPECT AN EXTENSION AS TIME
PROGRESSES. THE WINDS SHOULD BUILD SEAS TO 9 TO 14 FT ON THE OCEAN
(HIGHEST EASTERN ZONES) AND 3 TO 6 FT ON THE SOUND.
OCCLUDED FRONT/LOW CROSSES THE LONG ISLAND SUNDAY...WITH WINDS
SHIFTING TO THE W BY AFTERNOON...FOR NOW APPEARS THAT WILL AT LEAST
HAVE SCA SEAS ON THE OCEAN SUNDAY...AND POSSIBLY GUSTS TO SCA
LEVELS. SEAS SUBSIDE WITH DIMINISHED (RELATIVELY SPEAKING) WINDS.
INCREASING W WINDS SUN NIGHT-MONDAY BECOMING NW LATE MONDAY AND INTO
TUESDAY BEHIND AN ARCTIC FRONT. COULD SEE GALE FORCE GUSTS RETURN BY
LATE MONDAY...AND THEN LIKELY WITH STRONG COLD ADVECTION ON TUESDAY.
&&
.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 CTZ005.
NY...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO NOON EST
SATURDAY FOR NYZ067>070.
NJ...FREEZING RAIN ADVISORY FROM 6 PM THIS EVENING TO NOON EST
SATURDAY FOR NJZ002.
MARINE...GALE WATCH FROM SATURDAY MORNING THROUGH SATURDAY AFTERNOON
FOR ANZ335-338-345.
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST
SATURDAY FOR ANZ335-338-345.
GALE WARNING FROM 6 PM THIS EVENING TO 6 PM EST SATURDAY FOR
ANZ330-340-350-353-355.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM EST THIS
EVENING FOR ANZ350-353-355.
&&
$$
PUBLIC/HYDROLOGY...PW
AVIATION/MARINE...MALOIT
