Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 250340
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1040 PM EST WED DEC 24 2014

.SYNOPSIS...
A COLD FRONT CROSSES THE TRI-STATE AROUND SUNRISE. HIGH PRESSURE
THEN BUILDS TO THE SOUTH OF THE REGION THROUGH SATURDAY. A COLD
FRONT THEN CROSSES THE REGION ON SUNDAY AND STALLS WELL TO OUR
SOUTH ON MONDAY. A WEAK WAVE OF LOW PRESSURE MOVES ALONG THE FRONT
ON TUESDAY AND MAY BRUSH NEW YORK CITY AND LONG ISLAND. AT THIS
TIME NEW YEARS EVE AND DAY LOOK DRY WITH SEASONABLE TEMPERATURES.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
WARM FRONT HAS MOVED THROUGH MUCH OF THE REGION EXCEPT FOR THE
LOWER HUDSON VALLEY AND CENTRAL INTERIOR CONNECTICUT AS OF LATE
THIS EVENING. RADAR REFLECTIVITY IS WEAK WITH ECHOES MOVING IN
FROM THE WEST. A GENERAL MIST BEING REPORTED AT MOST SITES BUT
DRIZZLE AND RAIN COULD EASILY DEVELOP WITH SUCH A SATURATED
AIRMASS IN PLACE...ESPECIALLY ACROSS THE COAST. USED OCCASIONAL
WORDING FOR DRIZZLE AND RAIN UNTIL SHARPER TROUGH ASSOCIATED WITH
COLD FRONT APPROACHES FROM THE WEST. THIS WILL ALLOW FOR A
RELATIVELY MORE CONVECTIVE MODE WITH SOME SREF AND NAM SOUNDING
SHOWING SOME ELEVATED INSTABILITY AHEAD OF THE FRONT. SO...STILL
THINK IN A GENERAL 3-6AM TIMEFRAME...WILL HAVE A NARROW CONVECTIVE
LINE WITH PERHAPS SOME ISOLATED LIGHTNING STRIKES THAT WILL MOVE
ACROSS WEST TO EAST. OTHERWISE...AREAS OF DENSE FOG ALONG MUCH OF
THE COAST THAT WILL DECREASE WITH GREATER INTENSITY OF SHOWERS
LATE TONIGHT INTO EARLY THURSDAY MORNING.

TEMPERATURES ADJUSTED SLIGHTLY WITH AN INCREASE SLIGHTLY ACROSS
EASTERN LONG ISLAND.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
BASED ON LATEST NWP...HAVE MOVED UP THE ENDING OF PCPN FROM WEST TO
EAST TO EARLY MORNING AS THE COLD FRONT MOVES OFFSHORE. BEHIND THE
FRONTAL PASSAGE EXPECT DRY CONDITIONS WITH BELOW ADVISORY LEVEL
WIND GUST OF 30 TO 40 MPH. WINDS WILL DIMINISH CHRISTMAS NIGHT AS
THE FRONT PUSHES FURTHER EAST.

THE MAX TEMPERATURES FOR CHRISTMAS DAY SHOULD BE IN THE LOW TO MID
50S...WITH TEMPERATURES DROPPING OFF INTO THE 40S BY LATE AFTERNOON
AND EVENING. LOW TEMPERATURES CHRISTMAS NIGHT SHOULD BE IN THE UPPER
20 TO AROUND 30 INLAND...AND MID TO UPPER 30S ALONG THE COAST.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
NWP GUIDANCE HAS MADE A SIGNIFICANT SHIFT TODAY WITH THE SOUTHERN
BRANCH OF THE JET RESULTING A MORE PROGRESSIVE PATTERN. BASED ON
AGREEMENT OF GEFS WITH THE DETERMINISTIC GFS AND ECMWF TREND...HAVE
REPOPULATED FCST. 12Z GEM REMAINS MORE ACTIVE...BUT WAS NOT
INCORPORATED INTO THE FCST BASED ON GEFS/EC SIMILARITY.
THUS...FCSTING THE COLD FRONTAL PASSAGE ON SUNDAY...THEN SEASONABLE
AND DRY.

DUE TO THE SHIFT IN THE NWP...CONFIDENCE IS LOWER THAN NORMAL AND WE
COULD HAVE A WINDSHIELD WIPER EFFECTS IN THE DETERMINISTIC GUIDANCE.
ONLY POPS OUT SIDE OF THOSE WITH THE COLD FRONT ON SUNDAY ARE LATE
TUESDAY WITH A WEAK WAVE SEEN IN THE ECMWF. GEFS HAS SOME MEMBERS
THAT SUPPORT THIS FEATURE (NOT SEEN IN THE DETERMINISTIC GFS).
PARALLEL GFS ALSO SUPPORTS THE IDEA OF A WEAK LOW PASSING TO THE
SOUTH LATE TUESDAY.

AS FOR TEMPS...MOS HAS TRENDED HIGHER FRIDAY AND SATURDAY AND SEEMS
LOGICAL WITH TEMPS A GOOD 10 DEGREES ABOVE NORMAL ON SATURDAY.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
A WARM FRONTAL BOUNDARY HAS PUSHED NORTH OF CT TERMINALS...BUT
WILL BE SLOWER WORKING INTO NJ TERMINALS...AND PERHAPS NOT INTO
KSWF UNTIL JUST AHEAD OF COLD FRONTAL PASSAGE. MEANWHILE A COLD
FRONT WILL BE APPROACHING OVERNIGHT...CROSSING THROUGH THE AREA
FROM AROUND 09Z TO 13Z THURSDAY.

LIFR/VLIFR CONDS EXPECTED TO CONTINUE FOR KHPN/KLGA/KJFK AND
EASTERN TERMINALS IN THE WAKE OF THE WARM FRONT WITH ADVECTION
FOG. FOR KEWR/KTEB/KSWF...CONDITIONS MORE LIKELY REMAIN LIFR/IFR
TONIGHT...WITH A LOW PROBABILITY OF VLIFR.

ALTHOUGH WINDS A GUSTS HAVE SUBSIDED A BIT...WINDS WILL INCREASE
AHEAD OF THE COLD FRONT ONCE AGAIN AFTER 07Z TO S 15 TO 20 MPH
WITH GUSTS UP TO 30 MPH UNTIL COLD FRONTAL PASSAGE. A LOW LEVEL
S/SW JET STREAM OF 50 TO 60 KT WILL CONTINUE IN LOW LEVEL WIND
SHEAR UNTIL THE COLD FRONTAL PASSAGE.

PERIODS OF LIGHT RAIN AND DRIZZLE TONIGHT...AND THEN A BAND OF
MODERATE TO HEAVY RAIN WITH EMBEDDED TSTM LIKELY TO CROSS THE REGION
W TO E BETWEEN 06Z AND 13Z. POTENTIAL FOR AN ORGANIZED LINE OF
CONVECTION WITHIN THIS...WITH LOW PROB OF ISOLATED 40+ KT GUSTS.

CONDITIONS IMPROVE QUICKLY TO VFR WITH THE RAIN ENDING AS THE FRONT
MOVES THROUGH EARLY THU MORNING.

VFR ON THU...WITH 15 TO 20 KT WESTERLY WINDS WITH GUSTS 30 TO 35 KT.
LOW PROB OF GUSTS 35-40 KT.

.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.THU NIGHT...VFR. WIND AND GUSTS DIMINISHING.
.FRI-SAT...VFR.
.SUN...MARGINAL VFR. CHANCE OF RAIN AND SNOW.
.MON...VFR.

&&

.MARINE...
WAVES SLIGHT ADJUSTMENT DOWN FOR NEXT FEW HOURS ON THE OCEAN TO
BETTER MATCH OBSERVED TRENDS WITH OTHERWISE MARINE FORECAST
REMAINING ON TRACK.

DENSE ADVECTION FOG ON THE WATERS UNTIL JUST BEFORE MORNING WITH
THE COLD FRONTAL PASSAGE.

WINDS INCREASE ON ALL WATERS TO SCA LEVELS TONIGHT. SCA LEVEL
SEAS ON THE COASTAL OCEAN WATERS IN EFFECT WITH GUSTS TO GALE
FORCE LIKELY DEVELOPING CHRISTMAS MORNING AND CONTINUING INTO
EARLY EVENING. SCA GUSTS THEN EXPECTED FOR THE REMAINDER OF THE
EVENING...TAPERING OFF TO BELOW SCA LEVELS AFTER MIDNIGHT.

SUB-SCA CONDITIONS ARE ANTICIPATED ON FRIDAY INTO NEXT WEEK
THOUGH THERE IS UNCERTAINTY IN HOW FAR SOUTH THE STALLED FRONTAL
BOUNDARY WILL REMAIN NEXT WEEK.

&&

.HYDROLOGY...
UP TO THREE QUARTERS OF AN INCH OF RAINFALL HAVE FALLEN ACROSS THE
HYDROLOGIC SERVICE AREA...AND AN ADDITION ONE TO ONE AND A HALF
INCHES IS EXPECTED THROUGH CHRISTMAS MORNING. THE MAIN THREAT FROM
THIS IS MINOR URBAN AND POOR DRAINAGE FLOODING LIKELY.

DRY FRI-SATURDAY NIGHT. LIGHT PCPN IS POSSIBLE ON SUNDAY WITH THE
PASSAGE OF A COLD FRONT. AT THIS TIME...THE FRONT IS EXPECTED TO
STALL WELL TO OUR SOUTH LEAVING NEXT WEEK BASICALLY DRY...THOUGH
THERE IS UNCERTAINTY ON HOW FAR SOUTH THE FRONT WILL STALL.

&&

.CLIMATE...
RECORD MAXIMUM MINIMUMS FOR CHRISTMAS DAY...

LOCATION.......RECORD/YEAR
NEWARK.............47/1979
BDRIDGEPORT........45/1964
CENTRAL PARK.......50/1979
LAGUARDIA..........48/1964
JFK AIRPORT........46/1987
ISLIP AIRPORT......45/1987

THESE RECORDS LIKELY WILL NOT FALL AS TEMPERATURES ARE CURRENTLY
FORECAST TO FALL TO AROUND 40 DEGREES AT OR BEFORE 11:59 PM ON
THE 25TH.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...DENSE FOG ADVISORY UNTIL 6 AM EST THURSDAY FOR CTZ009>012.
NY...DENSE FOG ADVISORY UNTIL 6 AM EST THURSDAY FOR NYZ071-075-
     078>081-176>179.
NJ...NONE.
MARINE...DENSE FOG ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ330-335-338-
     340-345-350-353-355.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ330-335-
     338-340-345-350-353-355.
     GALE WARNING FROM 6 AM TO 7 PM EST THURSDAY FOR ANZ330-335-338-
     340-345-350-353-355.

&&

$$
SYNOPSIS...FIG/TONGUE
NEAR TERM...JM
SHORT TERM...FIG
LONG TERM...TONGUE
AVIATION...NV
MARINE...FIG/JM/TONGUE
HYDROLOGY...FIG/TONGUE
CLIMATE...








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