FXUS61 KOKX 231748
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1248 PM EST WED DEC 23 2009
.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL PASS TO OUR NORTH THIS
AFTERNOON...AS HIGH PRESSURE BUILDS SOUTH FROM ONTARIO THROUGH
CHRISTMAS EVE...THEN SLOWLY RETREATS NORTHEAST ON CHRISTMAS DAY.
A COMPLEX STORM SYSTEM WILL THEN IMPACT THE REGION FROM LATE
CHRISTMAS DAY INTO SUNDAY. HIGH PRESSURE WILL BUILD FROM THE WEST
FROM LATE SUNDAY INTO MONDAY NIGHT. A COLD FRONT WILL CROSS THE
REGION ON TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
TEMP FORECAST FOR THIS AFTERNOON...AFTER A FRIGID START WITH -6 AT
FOK IN THE LONG ISLAND PINE BARRENS AND SINGLE DIGITS ACROSS SW
CT...ARE NOW GENERALLY ON TRACK PER OKX 12Z SOUNDING AND LATEST
OBS...WITH HIGHS IN THE UPPER 20S INLAND TO LOWER 30S NYC/COASTAL
SECTIONS. KEEPING AN EYE ON SNOW BAND STRETCHING FROM SYRACUSE TO
ALBANY TO THE BERKSHIRES...FORCED BY H7 FRONTOGENESIS AND MID
LEVEL SHORTWAVE PIVOTING AROUND UPR LOW PASSING JUST NORTH OF
THE AREA. WOULD EXPECT DOWNSLOPE FLOW AND GREATER TEMP-DEWPOINT
DEPRESSIONS OVER SOUTHERN NEW ENGLAND TO DO THEIR JOB AND WEAKEN
THE BAND AS IT MOVES SOUTH...WITH ONLY SCATTERED FLURRIES AT MOST
OVER SOUTHERN CT...BUT IT WILL STILL HAVE TO BE WATCHED FOR SIGNS
OF HOLDING TOGETHER.
&&
.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 /18Z WEDNESDAY THROUGH MONDAY/...
UPPER LEVEL DISTURBANCE TO OUR NORTH WILL BRING SOME SCATTERED
CLOUDS AROUND 3KFT TO THE AREA TERMINALS THIS AFTERNOON. THERE MAY
BE A FEW LOCATIONS THAT GO BROKEN FOR A BRIEF PERIOD...HOWEVER
CONFIDENCE IS NOT HIGH ENOUGH TO KEEP IN THE TAFS. OTHERWISE...CLEAR
SKIES RETURN TONIGHT AND THURSDAY.
GUSTY WNW WINDS CONTINUE THROUGH EARLY EVENING. THE GUSTS ENDS THE
EVENING...WITH SUSTAINED WINDS BELOW 10 KT AFTER MIDNIGHT.
TAF COMMENTS (FORECASTER INSIGHT ON TIMING, CONFIDENCE, TRENDS AND GROUND OPS)
KEWR...WINDS WILL BE ON EITHER SIDE OF 310 THROUGH MUCH OF
THE DAY TODAY. BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KEWR HOURLY WIND FORECAST
ALL WIND DIRECTIONS ARE TRUE...ADD 13 DEGREES FOR MAGNETIC
23/16Z 29013G21KT
23/17Z 29015G23KT
23/18Z 30015G23KT
23/19Z 30015G23KT
23/20Z 31015G23KT
23/21Z 31014G22KT
23/22Z 31014G22KT
23/23Z 32013G21KT
24/00Z 32013G21KT
24/01Z 32013G21KT
24/02Z 32012G21KT
24/03Z 32012G22KT
KJFK...BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KLGA...WINDS WILL BE ON EITHER SIDE OF 310 THROUGH MUCH OF
THE DAY TODAY. BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KTEB...WINDS WILL BE ON EITHER SIDE OF 310 THROUGH MUCH OF
THE DAY TODAY. BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KHPN...WINDS WILL BE ON EITHER SIDE OF 310 THROUGH MUCH OF
THE DAY TODAY. BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KSWF...BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KISP...BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KBDR...BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
KGON...BROKEN CIGS AROUND 3000 FT POSSIBLE FOR AN HOUR OR
TWO THIS AFTERNOON.
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 EARLY SUNDAY
MORNING...WITH VFR RETURNING.
&&
.MARINE...
SCA CONDITIONS WILL PERSIST OVER THE EASTERN SOUND AND THE OCEAN
WATERS THROUGH TONIGHT AND PERHAPS THU MORNING. AS LOW PRESSURE
MOVES OFFSHORE...BUT THE PRESSURE GRADIENT REMAINS STRONG ENOUGH
TO REACH THE GUST CRITERIA. WESTERN SOUND/HARBOR/SOUTH SHORE BAYS
COULD SEE OCNL GUSTS TO 25 KT THROUGH THIS EVENING...WITH DURATION
NOW WARRANTING SCA.
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...
SNOW PACK HAS COMPACTED SOMEWHAT...WITH MOST MELTING REFREEZING IN
THE SNOW PACK AS MAX TEMPS HAVE REMAINED IN THE 30S. COULD SEE
SOME MELTING THU AND MORE LIKELY FRI AS HIGHS CLIMB CLOSER TO 40
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.
&&
$$
