FXUS61 KOKX 241131
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
631 AM 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/...
MID AND UPPER LOW TRAVERSES TO THE EAST TODAY...ALLOWING RIDGE TO
BUILD. HIGH PRESSURE AT THE SFC WILL RIDGE DOWN FROM SOUTHEAST
CANADA. VERY COLD TEMPS WILL REBOUND INTO THE 30S...BUT STILL FALL
SHORT OF SEASONAL NORMS. SCATTERED CLOUDS ANTICIPATED THROUGH THE
DAY TODAY.
&&
.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 /12Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS TO PREVAIL THROUGH TONGIHT. WINDS LIGHT AND GENERALLY
NORTHWEST TO START THE DAY GRADUALLY BECOMING NORTHEAST BY THIS
EVENING. FORECAST COMPLICATIONS START TO DEVELOP TONIGHT ACROSS THE
AREA. THE FORECAST PROBLEMS ARE GREATEST IN THE 18-30 HR PERIOD. THE
LOW CLOUDS EXPECTED TO DEVELOP EARLY XMAS MORNING. FORECAST
SOUNDINGS AND GOOD LOW LEVEL LIFT SUGGEST THAT DRIZZLE AND FOG MAY
BECOME A PROBLEM IN THE PREDAWN HOURS...MAINLY FOR THE WESTERN
TERMINALS. THE MAIN PROBLEM AT THAT TIME IS THAT SURFACE
TEMPERATURES WILL BE NEAR OR BELOW FREEZING AT THAT POINT AND
FREEZING DRIZZLE MAY BE A PROBLEM. CONFIDENCE OVERALL IS LOW BEYOND
06Z AS THERE ARE MODEL DIFFERENCES IN THE AMOUNT OF DRY AIR THAT
WILL HANG ON IN THE LOW LEVELS...AND TEMPERATURES WILL BE HOVERING
CLOSE TO THE FREEZING MARK. A DEGREE OR TWO WILL MAKE A BIG
DIFFERENCE.
TAF COMMENTS (FORECASTER INSIGHT ON TIMING, CONFIDENCE, TRENDS AND GROUND OPS)
KEWR...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS ANTICIPATED
KEWR HOURLY WIND FORECAST
ALL WIND DIRECTIONS ARE TRUE...ADD 13 DEGREES FOR MAGNETIC
24/10Z 31008KT
24/11Z 32007KT
24/12Z 32007KT
24/13Z 32007KT
24/14Z 33008KT
24/15Z 33008KT
24/16Z 34008KT
24/17Z 34007KT
24/18Z 35007KT
24/19Z 34008KT
24/20Z 33008KT
24/21Z 32008KT
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
KBDR...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS ANTICIPATED
KGON...FORECAST ON TRACK...NO UNSCHEDULED AMENDMENTS ANTICIPATED
OUTLOOK 12Z FRIDAY THROUGH MONDAY...
FRIDAY...SUB-VFR POSSIBLE AFTER MIDNIGHT WITH LOW CLOUDS AND/OR FOG.
-FZDZ ALSO POSSIBLE EARLY FRIDAY MORNING ALL TAF SITES.
FRIDAY NIGHT-SATURDAY NIGHT...IFR LIKELY. FZRA LIKELY INTO SAT
MORNING FOR KSWF...POSSIBLY KHPN...OTHERWISE RAIN EXPECTED. GUSTY
WINDS POSSIBLE INTO SAT. LLWS ALSO 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...
OUTSIDE OF ANZ-350 WINDS/SEAS HAVE FALLEN BELOW SCA LEVELS SO HAVE
CANCELLED ALL SCA/S OUTSIDE OF ANZ-350. IN ANZ-350 EXPECT GUSTS TO
SCA LEVELS THIS MORNING...AND SEAS OF UP TO 5 FT TO LAST THROUGH
LATE EVENING...SO HAVE EXTENDED THE SCA THERE UNTIL 11 PM TONIGHT.
HIGH PRESSURE BUILDING OVER THE WATERS WILL BRING RELATIVELY
TRANQUIL CONDITIONS TO THE WATERS BY LATE TONIGHT.
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...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR ANZ350.
&&
$$
SYNOPSIS...PW
NEAR TERM...PW
SHORT TERM...PW
LONG TERM...JC/PW
AVIATION...MANNING
MARINE...PFM
HYDROLOGY...PW
