FXUS61 KOKX 241756
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1256 PM EST THU DEC 24 2009
.SYNOPSIS...
HIGH PRESSURE REMAINS TO THE NORTH TODAY. MEANWHILE...A COMPLEX
STORM SYSTEM OVER THE MID WEST WILL SLOWLY TRACK TOWARD THE AREA
THIS WEEKEND. ICY CONDITIONS ARE EXPECTED FOR INTERIOR SECTIONS
FRIDAY NIGHT INTO SATURDAY MORNING...AND HEAVY RAIN THROUGHOUT THE
TRI-STATE AREA ON SATURDAY. THE STORM WILL DEPART AND COLDER AIR
WILL RETURN NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TEMPS HAVE BEEN BUMPED UP A DEGREE OR TWO BASED ON CURRENT
CONDITIONS...TRENDS AND LATEST LAMP GUIDANCE. WINDS HAVE BEEN
VEERED TO NORTH OR NORTHEAST FOR THE SAME REASONS.
LOW LEVEL MOISTURE SUGGEST A FEW MORE CLOUDS THAN PREVIOUSLY
FCST...BUT STILL A MOSTLY SUNNY DAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
PHASING OCCURS AS UPPER MID WEST ENERGY DIVES SOUTHWARD AND CARVES
OUT LARGE CLOSED LOW OVER THE MID WEST. THIS LARGE CUT OFF SLOWLY
MAKES EASTWARD PROGRESS THROUGH THE PERIOD. FOR TONIGHT...WINDS
TURN TO THE EAST AS HIGH PRESSURE MOVES EASTWARD AND MID WEST
FRONTAL SYSTEM APPROACHES. INVERSION DEVELOPS...AND WARMER AIR OVER
THE COLDER BOUNDARY LAYER TEMPS WILL RESULT IN THE DEVELOPMENT OF
FOG OVERNIGHT AS T/TD SPREADS SHRINK. BOTH TIME HEIGHTS FROM NAM/GFS
DO SHOW PLENTY OF LOW LEVEL MOISTURE UNDERNEATH INVERSION. HOWEVER
DEPTH OF THIS MOISTURE DIFFERS AS NAM MUCH MORE SHALLOW.
MOST MODELS OUTPUT LIGHT QPF...WITH ISENTROPIC LIFT IN SATURATED
LAYER RESULTING IN DRIZZLE LATE TONIGHT AND EARLY FRIDAY MORNING.
THIS WOULD BE PROBLEMATIC AS SFC TEMPS DROP BELOW FREEZING ACROSS
MOST PLACES. HARD TO FORECAST EXACTLY WHERE ANY DRIZZLE DOES IN FACT
OCCUR...BUT IT LOOKS LIKE NORTHERN SECTIONS...PARTICULARLY SRN CT
WILL BE THE LEAST LIKELY PLACES. OTHERWISE...IF DRIZZLE DOES
OCCUR...IT WILL FREEZE AND THIS WOULD POSE PROBLEMS ACROSS PORTIONS
OF THE AREA. NO WINTER WX ADVISORIES YET AS CONFIDENCE REMAINS LOW ATTM.
OTHERWISE...NAM AND EC MUCH SLOWER IN SWEEPING WARM AIR ADVECTION
RAINS ACROSS THE REGION LATER FRIDAY AND SATURDAY AS COMPARED TO
GFS. LEANED TOWARD SLOWER SOLUTION...WHICH IS A DELAY FROM EARLIER
DATABASE. SFC TEMPS WARM FRIDAY...BUT INTERIOR LOCATIONS MAY NOT
RISE MUCH ABOVE FREEZING. WITH AMPLE COLD AIR DAMMING AND EAST
FLOW...INTERIOR LOCATIONS COULD SEE A SIGNIFICANT ICING EVENT
FRIDAY NIGHT INTO SATURDAY MORNING. AGAIN...TOUGH TO FORECAST THIS
PERFECTLY...BUT WILL NEED TO KEEP AN EYE ON TEMP TRENDS AS THE
EVENT NEARS.
OTHER CONCERN IS FOR MODERATE TO HEAVY RAINFALL OUT AHEAD OF THE WARM
FRONT SATURDAY NIGHT SATURDAY NIGHT. IF WE DO SEE 1 TO 2 INCH
AMOUNTS (00Z NAM > 2 INCHES FOR PORTIONS OF THE AREA)...FLOODING
WOULD MOST DEFINITELY BE A CONCERN. RIGHT NOW...SNOW WATER EQUIV
RANGES FROM ABOUT 1/2 TO 1 INCH FROM NYC NORTH AND WEST...TO UP TO
3 INCHES EASTERN LI AND SE CT. WITH SNOW PACK CLOGGING
DRAINS...RAIN AND SUBSEQUENT SNOW MELT HAS NOWHERE TO GO.
CONTINUE MENTION IN HWO FOR ALL THE ABOVE CONCERNS.
FOLLOWED MOS BLEND FOR TEMPS...BUT WHERE LARGE DISCREPANCIES WERE
NOTED...LEANED TOWARD COLDER SOLUTION.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
FRONTAL SYSTEM PASSES EAST SUNDAY AS DRIER AIR RUSHES IN.
CLOSED MID AND UPPER LEVEL LOW OPENS UP AS IT PIVOTS ACROSS THE
NORTHEAST. THIS COULD RESULT IN SCATTERED RAIN AND SNOW SHOWERS
SUNDAY NIGHT THROUGH MONDAY. COLD AIR ADVECTION RETURNS BEHIND THIS
SYSTEM FOR EARLY NEXT WEEK. IN FACT...A SHOT OF EVEN COLDER AIR
IS FORECAST BEHIND A COLD FRONT DROPPING DOWN OUT OF CANADA LATE
MONDAY NIGHT INTO TUESDAY MORNING. AGAIN...A SLIGHT CHANCE OF SNOW
SHOWERS OR FLURRIES DURING THIS TIME. WITH 850 MB TEMPS FALLING TO
AROUND -12C...HIGHS ONLY IN THE MID 30S EXPECTED ON TUESDAY. HIGH
PRESSURE THEN DOMINATES THE WEATHER THROUGH THE REST OF THE LONG
TERM WITH DRY WEATHER.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR THROUGH THIS EVENING.
WIND GUSTS CONTINUE TO DIMINISH FROM WEST TO EAST ACROSS THE REGION.
WIND SPEEDS EXPECTED TO DROP BELOW 10 KTS THIS AFTERNOON.
DIRECTIONS MAY VARY A BIT FROM FORECAST DIRECTIONS AND MAY BE
LIGHT AND VARIABLE AS THEY CONTINUE TO TREND TO THE NORTHEAST AFT
20Z.
HIGH CONFIDENCE IN DEVELOPMENT OF MVFR/IFR CIGS TONIGHT...HOWEVER
GIVEN ABUNDANT MOISTURE NE OF THE REGION...ONSET MAY BE EARLIER.
WOULD ALSO CAUTION THAT PERIODS OF LIFR CIGS ARE POSSIBLE AFTER 06Z
FRIDAY.
TAF COMMENTS (FORECASTER INSIGHT ON TIMING, CONFIDENCE, TRENDS AND GROUND OPS)
KEWR...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED. SCT-BKN 030-040 PSBL THIS AFTERNOON.
KEWR HOURLY WIND FORECAST
ALL WIND DIRECTIONS ARE TRUE...ADD 13 DEGREES FOR MAGNETIC
24/16Z 01010KT
24/17Z 02010KT
24/18Z 02009KT
24/19Z 02008KT
24/20Z 02008KT
24/21Z 02008KT
24/22Z 02007KT
24/23Z 02007KT
25/00Z 02007KT
25/01Z 03006KT
25/02Z 04006KT
25/03Z 05005KT
KJFK...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
KLGA...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
KTEB...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
KHPN...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
KSWF...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
KISP...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED TODAY. SOME CONCERN ABOUT REDUCED CONDITIONS WITH FOG
TONIGHT GIVEN DEEP SNOW PACK.
KBDR...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
KGON...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS
ANTICIPATED
OUTLOOK 18Z FRIDAY THROUGH MONDAY...
FRIDAY...SUB-VFR WITH LOW CLOUDS AND/OR FOG.
FRIDAY NIGHT-SATURDAY NIGHT...IFR LIKELY. FZRA LIKELY INTO SAT
MORNING FOR KSWF...POSSIBLY KHPN...OTHERWISE RAIN EXPECTED. GUSTY NE
WINDS POSSIBLE INTO SAT. LLWS POSSIBLE.
SUNDAY...RAIN TAPERING OFF FROM W-E EARLY SUNDAY MORNING...WITH
VFR RETURNING. GUSTY W WINDS POSSIBLE.
SUN NIGHT-MON NIGHT...-SHSN POSSIBLE SUN NIGHT AND MON NIGHT. COLD
FROPA MON NIGHT WITH GUSTY NW WINDS IN ITS WAKE.
&&
.MARINE...
WINDS/SEAS HAVE FALLEN BELOW SCA LEVELS OVER EASTERN OCEAN
ZONE...THOUGH AN OCCASIONAL GUST TO 25 KT IS STILL INCLUDED.
OTHERWISE...HIGH PRESSURE BUILDING OVER THE WATERS WILL BRING
RELATIVELY TRANQUIL CONDITIONS TO THE WATERS INTO CHRISTMAS DAY.
AREAS OF FOG OVERNIGHT WILL LOWER VISIBILITY SLIGHTLY.
HIGH PRESSURE BUILDING INTO OUR NORTH AND LOW PRESSURE
APPROACHING FROM THE SOUTHWEST WILL CREATE A GRADUALLY
STRENGTHENING NE FLOW TONIGHT AND FRIDAY MORNING...WHICH THEN
BECOMES EAST AND CONTINUES TO STRENGTHEN FROM FRIDAY AFTERNOON
INTO SATURDAY NIGHT. EXPECT SMALL CRAFT CONDITIONS TO DEVELOP ON
ALL WATERS BY FRIDAY EVENING WITH GALE CONDITIONS (MAINLY GUSTS TO
GALE FORCE) LIKELY FROM OVERNIGHT FRIDAY NIGHT THROUGH SATURDAY
NIGHT. PERSISTENT EASTERLY FLOW WILL BUILD SEAS TO 8-11 FT ON THE
OCEAN BY SATURDAY AFTERNOON AND TO 3 TO 6 FT ON THE SOUND.
AN AREA OF LOW PRESSURE WILL CROSS THE TRI-STATE SUNDAY...WITH WINDS
VEERING TO THE SE AHEAD OF IT AND SHIFTING TO THE W THEN NW BEHIND
IT. COLD ADVECTION BEHIND THE LOW SHOULD LEAD TO GUSTY NW FLOW ON
MONDAY...SO EXPECT SMALL CRAFT CONDITIONS ONCE THE GALE IS DONE INTO
EARLY NEXT WEEK.
&&
.HYDROLOGY...
SNOW PACK HAS COMPACTED SOMEWHAT...BUT WITH LITTLE IF ANY RUNOFF
OCCURRING AS MAX TEMPS HAVE RISEN NO HIGHER THAN THE 30S. SOME SNOW
MELT POSSIBLE TODAY...BUT NOT MUCH AS TEMPS BARELY RISE ABOVE FREEZING
FOR A SHORT DURATION. POTENTIAL EXISTS FOR AN INCH OR MORE OF LIQUID
EQUIVALENT QPF...MAINLY LATE FRI NIGHT THROUGH SUN MORNING. THIS
POTENTIAL QPF FALLS ON TOP OF SNOW PACK. WATER EQUIVALENT IN THE
SNOW PACK AROUND 1/2 TO 1 INCH FROM NYC NORTH AND WEST TO UP TO 3
INCHES OVER EASTERN LI AND SE CT. THIS COMBINATION OF SIGNIFICANT
SNOW PACK AND MODERATE TO HEAVY HEAVY RAIN COULD LEAD TO BOTH
URBAN AND SMALL RIVER/STREAM FLOODING SAT INTO SUN...DEPENDING ON
SPEED OF SNOW MELT AND DURATION OF HEAVIER RAIN.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...PW
NEAR TERM...JST/PW
SHORT TERM...PW
LONG TERM...JC/PW
AVIATION...BS
MARINE...JST/PFM
HYDROLOGY...PW
