FXUS61 KOKX 231145
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
645 AM EST WED DEC 23 2009
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE PASSES TO OUR NORTH TODAY...AS HIGH
PRESSURE BUILDS SOUTH FROM ONTARIO THROUGH CHRISTMAS EVE...THEN
SLOWLY RETREAT NORTHEAST ON CHRISTMAS. A COMPLEX STORM SYSTEM WILL
THEN IMPACT THE REGION FROM LATE CHRISTMAS INTO SUNDAY. HIGH
PRESSURE BUILDS IN FROM THE WEST FROM LATE SUNDAY INTO MONDAY
NIGHT. A COLD FRONT CROSSES THE REGION ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATEST IR ILLUSTRATES CLOUDS REMAIN N AND NW OF THE CWA AS OF
11Z. THIS WILL NOT LAST LONG AS A COMPACTED H5 CYCLONE EVIDENT IN
THE 6.7U SATELLITE PICTURE PIVOTS FM NORTHERN NEW ENGLAND S THROUGH
EASTERN MASS. NO PRECIPITATION IS FORESEEN WITH THIS FEATURE DUE
LACK OF SUFFICIENT MOISTURE /PWATS LESS THAN 0.30 INCHES/. A
PERIOD OF STRATO-CU IS PREDICTED DURING THE MIDDAY AND AFTERNOON
HOURS...ESPECIALLY EAST OF THE CITY. THE SYSTEM EXITS TONIGHT
OWING TO DECREASING CLOUDS...HOWEVER WITH A MID LEVEL SHORTWAVE
CROSSING OVERHEAD...SCATTERED MID CLOUDS WILL BE AROUND. BOUNDARY
LAYER COLD ADVECTION COUPLED WITH LOWEST SUN ANGLE OF THE YEAR
EQUATES TO NO MORE THAN A TEN DEGREE TEMPERATURE SPREAD FROM DAWN
READINGS. ALL GUIDANCE HAS COME IN A FEW DEGREES COOLER THAN
INHERITED FORECAST...SO ADJUSTED THE HIGH TEMPERATURE DOWNWARD
WITH MOST PLACES BELOW 32F TODAY.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
HIGH CONFIDENCE FORECAST WITH A SURFACE ANTICYCLONE NOSING SOUTH
FROM ONTARIO YIELDING DRY BUT CONTINUED BELOW NORMAL WEATHER. FAST
FLOW AT MID LEVEL LEADS TO PASSING ALTO-CU...BUT PLENTY OF SUNSHINE
AS WE APPROACH CHRISTMAS. H8 TEMPERATURES SURPASS 0C THUR
AFTERNOON...SO THAT WILL HELP ERODE EXISTING SNOW PACK. THE HIGH
SHOULD BE AROUND 40F THUR. SURFACE FLOW TURNS EASTERLY THURSDAY
NIGHT AND THAT COULD LEAD TO FOG WITH WEAK WAA OVER SNOW-PACK.
CONTINUED MENTION OF PATCHY FOG IN THE SUITE OF TEXT AND DIGITAL
PRODUCTS.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
HIGH PRES SLOW TO DEPART THE REGION FRI AS CLOSED LOW OVER THE UPPER
MIDWEST SLOWLY TRACKS EAST. WITH SLOWER TRACK FAVORED BY 00Z/23
ECMWF AND NAM...WILL PUSH BACK START TIME OF HIGHER POPS UNTIL LATE
FRI NIGHT/SAT...THEN WILL BUMP UP POPS TO LOW-END CATEGORICAL SAT
NIGHT.
WITH 1040 MB HIGH ACROSS EASTERN CANADA FRI NIGHT THROUGH SAT
MORNING...COLD AIR AT THE SFC SHOULD BE TRAPPED WITH ONSET OF
PRECIPITATION AND A WIDESPREAD FREEZING RAIN EVENT IS POSSIBLE
ACROSS THE LOWER HUDSON VALLEY AND INTERIOR CT DURING THIS TIME.
TEMPS WARM UP ABOVE FREEZING SAT MORNING...THEN SHOULD STAY ABOVE
FREEZING FOR BULK OF THE EVENT. COLD FRONT OUT AHEAD OF THE NEARLY
VERTICALLY STACKED CLOSED LOW OVER THE UPPER MIDWEST APPROACHES
DURING THE DAY SAT...AND A SECONDARY LOW WILL DEVELOP OVER THE
DELMARVA AREA SAT...LIFTING THROUGH THE LOCAL AREA SAT NIGHT. BOTH
THE GFS AND THE ECMWF FAVOR BRINGING A SLUG OF HEAVY PRECIP
THROUGH THE REGION SAT NIGHT...SO WILL MENTION RAIN HEAVY AT
TIMES.
HEAVY RAIN AND MELTING SNOW-PACK WILL LIKELY LEAD TO FLOODING
ISSUES...WITH LOCAL RIVER RISES ACROSS THE INTERIOR AND URBAN
FLOODING ACROSS NYC/LONG ISLAND.
SYSTEM DEPARTS ON SUN...AND PRECIP TAPERS OFF.
MIDWEST STORM SYSTEMS SIGNIFICANTLY WEAKENS BY THE TIME IT TRACKS
ACROSS THE LOCAL AREA EARLY IN THE NEW WEEK. WILL ONLY CARRY
SLIGHT CHANCE POPS.
A STRONG NW FLOW WILL DEVELOP MON AND TUE...WITH TEMPERATURES
DROPPING BACK INTO THE 30S FOR HIGHS.
HIGH PRES BUILDS OVER THE AREA WED.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
UPPER LEVEL DISTURBANCE PASSING TO OUR NORTH WILL BRING SOME LOW END
VFR CEILINGS TO THE REGION THIS AFTERNOON (ABOUT A 35 PERCENT CHANCE
OF HIGH END MVFR...BUT NOT CONFIDENT ENOUGH TO REFLECT IN TAFS AT
THIS TIME)...OTHERWISE SKC WITH HIGH PRESSURE BUILDING IN AT THE
SURFACE FROM SOUTH-CENTRAL CANADA.
WNW WINDS BECOME GUSTY OUT OF THE NW BY MID MORNING...AND CONTINUE
THROUGH EARLY EVENING. GUSTINESS ENDS EARLY EVENING...WITH SUSTAINED
WINDS BELOW 10 KT BY AROUND/SHORTLY AFTER MIDNIGHT.
TAF COMMENTS (FORECASTER INSIGHT ON TIMING, CONFIDENCE, TRENDS AND GROUND OPS)
KEWR...WINDS VEER TO RIGHT OF 310 BY MID AFTERNOON - HIGH
CONFIDENCE. LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KEWR HOURLY WIND FORECAST
ALL WIND DIRECTIONS ARE TRUE...ADD 13 DEGREES FOR MAGNETIC
23/11Z 28006KT
23/12Z 28007KT
23/13Z 29007KT
23/14Z 29010G16KT
23/15Z 30012G18KT
23/16Z 30013G19KT
23/17Z 31014G20KT
23/18Z 31015G21KT
23/19Z 31014G20KT
23/20Z 31015G21KT
23/21Z 31014G20KT
KJFK...LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KLGA...WINDS VEER TO RIGHT OF 310 BY EARLY AFTERNOON - HIGH
CONFIDENCE. LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KTEB...WINDS VEER TO RIGHT OF 310 BY MID MORNING -
MEDIUM CONFIDENCE. LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS
MORNING.
KHPN...WINDS VEER TO RIGHT OF 310 BY MID MORNING - MEDIUM
CONFIDENCE. LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KSWF...LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KISP...LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KBDR...LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
KGON...LOW CONFIDENCE IN TIMING ONSET OF GUSTS THIS MORNING.
OUTLOOK 12Z THURSDAY THROUGH SUNDAY...
THURSDAY...VFR.
THURSDAY NIGHT-FRIDAY...SUB-VFR POSSIBLE WITH LOW CLOUDS AND/OR
FOG. -FZRA OR -FZDZ ALSO POSSIBLE INLAND FRI AFTERNOON
(KHPN/KSWF).
FRIDAY NIGHT-SATURDAY NIGHT...SUB VFR. FZRA POSSIBLE
INTO SAT MORNING FOR KSWF/KHPN...OTHERWISE WINTRY MIX/RAIN
BECOMING ALL RAIN FRIDAY NIGHT (LOWEST CHANCE OF MIX
KLGA/KJFK/KEWR). GUSTY ENE-E WINDS FRI NIGHT BECOMING SE
SATURDAY...THEN S SATURDAY NIGHT. LLWS ALSO POSSIBLE.
SUNDAY...RAIN LIKELY TAPERING OFF FROM W-E STARTING SUNDAY
AFTERNOON...WITH VFR RETURNING.
&&
.MARINE...
SCA CONDITIONS PERSIST OVER EASTERN L.I. SOUND AND THE OCEAN WATERS
THROUGH TONIGHT AND PERHAPS THUR MORNING. AS LOW PRESSURE MOVES
OFFSHORE...BUT THE PRESSURE GRADIENT REMAINS STRONG ENOUGH TO REACH
THE GUST CRITERIA.
SCA CONDITIONS LIKELY WITH MARGINAL GALES ON THE OCEAN WITH
PASSAGE OF STORM SYSTEM FRI THROUGH SUN. SCA CONDITIONS LIKELY
EARLY IN THE NEW WEEK WITH STRONG NW FLOW.
&&
.HYDROLOGY...
MELTING OF SNOW PACK CONTINUES THU-FRI AS TEMPS CLIMB TO NEAR 40F
IN NYC METRO AND COASTAL SECTIONS.
POTENTIAL EXISTS FOR AN INCH OR MORE OF LIQUID EQUIVALENT
QPF...MAINLY LATE FRI NIGHT THROUGH SUN MORNING...ON TOP OF SNOW
PACK WITH ABOUT 1-2 INCHES WATER EQUIVALENT IN MOST
PLACES...LESSER NORTH/WEST OF NYC. THIS COULD LEAD TO BOTH URBAN
AND SMALL RIVER/STREAM FLOODING...DEPENDING ON SPEED OF SNOW MELT
AND DURATION OF HEAVIER RAIN.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST THURSDAY FOR ANZ350-353-
355.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330-
340.
&&
$$
SYNOPSIS AND NEAR/SHORT TERM...98
LONG TERM...MPS
AVIATION...MALOIT
MARINE...98/MPS
HYDROLOGY...98/MPS
