000
FXUS61 KOKX 242342
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
642 PM EST TUE DEC 24 2013
.SYNOPSIS…
A COLD FRONT MOVES THROUGH THE REGION THIS EVENING FOLLOWED BY
CANADIAN HIGH PRESSURE FOR CHRISTMAS. A WEAK COLD FRONT MOVES ACROSS
THE REGION THURSDAY FOLLOWED BY HIGH PRESSURE BUILDING IN FROM
THE SOUTH AND WEST THROUGH THE WEEKEND. A STRONG COLD FRONT MOVES
ACROSS THE REGION LATE SUNDAY INTO MONDAY…WITH ARCTIC HIGH
PRESSURE BUILDING INTO THE REGION THROUGH EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/…
POTENTIAL FLASH FREEZE/ICING EVENT THIS EVENING…
BAND OF SNOW SHOWERS AND EMBEDDED SNOW SQUALLS OVER NE NJ/LOWER
HUDSON VALLEY…AHEAD OF APPROACHING MESO LOW…WILL CONTINUE TO
SLIDE SE ACROSS AREA THIS EVENING. BRIEF WHITEOUT CONDITIONS WITH
A QUICK 1/2 INCH OF SNOW AND 30 MPH WIND GUSTS HAVE BEEN REPORTED
ACROSS NW NJ…WITH SIMILAR CONDITIONS LIKELY ACROSS NE NJ AND
BORDERING LOWER HUDSON VALLEY ZONES THROUGH 7 PM. BASED ON TRACK
OF MES0-LOW WOULD EXPECT HEAVIEST ACTIVITY TO CONTINUE SE INTO THE
NYC METRO AREA AND LI/CT/NY SURROUNDINGS BETWEEN 7 AND 8 PM. THEN
ACROSS EASTERN LI/SE CT BTWN 8 AND 9 PM. ADDITIONAL LIGHT SNOW
SHOWER AND FLURRY ACTIVITY POSSIBLE BEHIND INITIAL BAND…BUT
LITTLE ADDITIONAL ACCUM EXPECTED.
THREAT FOR FLASH FREEZE CONTINUES AS TEMPS DROP QUICKLY WITH
ARCTIC FRONT/SNOW SHOWER PASSAGE. THIS WILL FREEZE THE LIGHT
COATING OF SLUSH THAT SHOULD COVER ABOUT 40-60% OF THE AREA.
PREVIOUS AFD…
UPPER TROF WITH ARCTIC FRONT PASSES OVER THE
REGION THIS EVENING. AS OF 19Z…FRONT IS PASSING THROUGH EASTERN
PA WITH INSTABILITY SNOW SHOWERS. TIME OF ARRIVAL FOR OUR AREA IS
SET FOR EARLY EVENING (6-8 PM IN THE NY METRO). ATMOSPHERE
SUPPORTS SNOW…DESPITE CURRENT SFC TEMPS OF 35-40. THIS IS A
PROBLEM.
LOW LEVEL INSTABILITY IS SIGNIFICANT THIS EVENING WITH SFC TO 950
HPA LAPSE RATES IN EXCESS OF 9 C / KM ALONG WITH NARROW CAPE (50-100
J) UP TO 600 HPA. CONFIDENT THAT SNOW SHOWERS/SQUALLS SEEN ON
RADAR WILL MAKE IT INTO THE LOCAL FCST AREA DUE TO DYNAMICS. COULD
EVEN HAVE SOME SNOW PELLETS/GRAUPEL. PCPN RAPIDLY MOVES THROUGH.
WFO BURLINGTON SNOW SQUALL STUDY PARAMETER SUPPORTS THIS THINKING
WITH PEAK SIGNAL AROUND 7 PM OVER NY METRO FROM 12Z RUN.
THE UNCERTAINTY REVOLVES ON THE AMOUNT AND LOCATION OF SNOW. AT
MOST…THINKING OF A FEW HUNDREDTHS, BUT THAT`S ALL IT TAKES.
CURRENTLY, HAVE POPS AT 50% FOR COVERAGE. ISSUED AN SPS FOR ALL
LOCATIONS.
&&
.SHORT TERM /MIDNIGHT THROUGH 6 PM WEDNESDAY/…
THIS IS A GOOD QUICK SHOT COLD AIR. MINS BY CHRISTMAS MORNING IN
THE TEENS TO LOWER 20S IN THE NY METRO. FOR MAXES HAVE HEDGED
TOWARDS THE COLDER GFS NUMBERS WITH MORE CLOUDS EXPECTED DUE TO
JET STREAK ENTRANCE/EXIT REGION OVER THE AREA. ALSO USED RH WITH
RESPECT TO ICE TO GIVE A MOSTLY CLOUDY AFTN.
CLOUDS CONTINUE CHRISTMAS NIGHT AND THUS LEANING TO SLIGHTLY
WARMER THAN MOS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/…
MODELS IN GOOD AGREEMENT WITH A STRONG SHORTWAVE SLIDING ACROSS THE
NORTHEAST ON THURSDAY…WITH ASSOCIATED CLIPPER SYSTEM MOVING ACROSS
NEW ENGLAND.
WAA FLOW AHEAD OF APPROACHING COLD FRONT AND OVER RETREATING ARCTIC
AIRMASS SHOULD ALLOW FOR SOME SNOW SHOWER ACTIVITY TO DEVELOP OVER
THE REGION THURSDAY MORNING…WITH POTENTIAL FOR A BRIEF PERIOD OF
MODERATE SNOW ACROSS THE INTERIOR AND RAIN/SNOW ALONG THE COAST
AHEAD OF STRONG SHORTWAVE ENERGY. BEST CHANCE FOR THIS WOULD BE
ACROSS EASTERN AREAS AS ATLANTIC MOISTURE GETS INCORPORATED. FOR NOW
HAVE RAISED POPS TO CHANCE FOR EASTERN AREAS.
SHORTWAVE AND FRONT MOVES EAST OF THE AREA THURSDAY NIGHT WITH HIGH
PRESSURE BUILDING IN FROM THE SOUTHWEST TO END THE WEEK INTO THE
WEEKEND. THIS SHOULD BRING DRY AND MODERATING TEMPS FRI INTO SAT.
TEMPS ON SAT HAVE POTENTIAL TO PUSH 50 ACROSS CITY/INTERIOR WITH
W/SW FLOW AND WAA AHEAD OF NEXT APPROACHING SHORTWAVE.
SOME UNCERTAINTY CREEPS IN FOR SAT NIGHT/SUN WITH AMOUNT OF
INTERACTION OF SOUTHERN STREAM ENERGY OVER WEST TEXAS AND THE LARGE
SCALE NORTHERN STREAM TROUGHING AROUND THE HUDSONS BAY POLAR VORTEX.
12Z ECMWF IS INDICATING A LARGER DEGREE OF PHASING WITH POTENTIAL
COASTAL LOW DEVELOPMENT FOR SUN/SUN NIGHT. BASED ON ENSEMBLE MODELS
AND HPC WILL MAINTAIN CONSISTENCY WITH AN UNPHASED SETUP AND MAINLY
A DRY COLD FRONTAL PASSAGE AS LOW PRESSURE AREAS PASS TO THE NORTH
AND SOUTH OF THE REGION. DUE TO PREDICTABILITY ISSUES WITH
NORTHERN/SOUTHERN STREAM PHASING…WILL HAVE TO MONITOR POTENTIAL
FOR END OF WEEKEND COASTAL STORM AS IT IS NOT OUT OF THE REALM OF
POSSIBILITIES…BUT JUST A LOW POTENTIAL AT THIS POINT.
HUDSONS BAYS POLAR VORTEX CONTINUES TO SLOWLY SINK SE THROUGH EARLY
NEXT WEEK WITH ARCTIC AIRMASS GRADUALLY SINKING SOUTH INTO THE
NORTHEAST US. MAIN STORY WILL BE A RETURN TO COLD WEATHER. WILL HAVE
TO MONITOR CLOSED PAC UPPER LOW OVER BAJA EARLY NEXT WEEK…FOR ITS
INTERACTION WITH NORTHERN STREAM AND POTENTIAL FOR MID TO LATE WEEK
COASTAL STORM.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/…
A TROUGH ACROSS THE AREA EARLY THIS EVENING WILL PRODUCE
SCATTERED SNOW SHOWERS WITH A BRIEF PERIOD OF IFR CONDITIONS
POSSIBLE THROUGH 03Z. THE NYC METRO TERMINALS…KSWF…KHPN…AND
KISP CONTINUE TO BE THE MOST FAVORED LOCATIONS.
MODERATE TO HIGH CONFIDENCE IN WINDS…ALTHOUGH TIMING OF GUSTS MAY
BE +/- AN HOUR OR SO. GUSTS SHOULD BE LOST AROUND DAYBREAK.
HIGH PRES BUILDS OVER THE AREA ON WED…WITH VFR CONDS WITH
LIGHTENING WINDS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT…
DETAILED INFORMATION…INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: WINDS WILL SHIFT BACK RIGHT OF 310 MAG
AT 01-02Z. SPEEDS/GUSTS MAY BE A FEW KT HIGHER THAN FORECAST.
KJFK FCSTER COMMENTS: WINDS MAY BRIEFLY VARY TO THE LEFT OF 310
MAGNETIC BETWEEN 00Z AND 03Z…THEN SHIFT BACK RIGHT OF 310.
SPEEDS/GUSTS MAY BE A FEW KT HIGHER THAN FORECAST.
KLGA FCSTER COMMENTS: WINDS MAY BRIEFLY VARY TO THE LEFT OF 310
MAGNETIC BETWEEN 00Z AND 03Z…THEN SHIFT BACK RIGHT OF 310. SPEEDS/GUSTS
MAY BE A FEW KT HIGHER THAN FORECAST.
KTEB FCSTER COMMENTS: SPEEDS/GUSTS MAY BE A FEW KT HIGHER THAN
FORECAST.
KHPN FCSTER COMMENTS: SPEEDS/GUSTS MAY BE A FEW KT HIGHER THAN
FORECAST.
KISP FCSTER COMMENTS: SPEEDS/GUSTS MAY BE A FEW KT HIGHER THAN
FORECAST.
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SUNDAY…
.WED NIGHT…VFR.
.THU…MAINLY VFR…EXCEPT BRIEF SUB-VFR POSSIBLE IN AFTERNOON SNOW
SHOWERS.
.THU NIGHT-SAT…VFR. GUSTY W/SW FLOW FRI AFT.
.SUN…VFR. GUSTY WEST FLOW.
&&
.MARINE…
WITH A SURGE OF ARCTIC COLD AIR THIS EVENING….GUSTS INCREASE TO
SMALL CRAFT LEVELS…AND MAY BRIEFLY APPROACH GALE FORCE.
WINDS AND SEAS THOUGH QUICKLY SUBSIDE BY SUNRISE AS HIGH PRESSURE
BUILDS IN. TRANQUIL CONDITIONS THEN EXTEND INTO THURSDAY MORNING.
A COLD FRONT WILL PUSH ACROSS THE AREA WATERS DURING THE DAY ON
THURSDAY…WHICH COULD BRING SOME MARGINAL SMALL CRAFT STRENGTH
GUSTS TO THE AREA WATERS THUS AFT. SCA CONDS LIKELY ON THE OCEAN AND
POSSIBLE ALL WATERS IN ITS WAKE WITH TIGHTENING NW GRADIENT AND SHOT
OF CAA.
THEN SUB-SCA CONDITIONS LIKELY RETURN FRIDAY INTO SATURDAY AS HIGH
PRESSURE BUILDS INTO THE WATERS. ANOTHER CHANCE OF SMALL CRAFT
CONDITIONS RETURNS ON SUNDAY WITH THE APPROACH OF ANOTHER COLD FRONT.
&&
.HYDROLOGY…
POTENTIAL FOR SIGNIFICANT WIDESPREAD PRECIP THROUGH EARLY NEXT WEEK
IS LOW.
&&
.EQUIPMENT…
THE NEW YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 IS
OUT OF SERVICE.
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD EMERGENCY
BROADCAST CHANNEL…THE NEW YORK CITY NOAA ALL HAZARDS WEATHER
RADIO STATION KWO35 IS OUT OF SERVICE.
DURING THE TIME…THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS WEATHER RADIO
DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS…FOR ROUTINE
WEEKLY TEST OF THE WARNING SYSTEM…AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…NONE.
NJ…NONE.
MARINE…SMALL CRAFT ADVISORY UNTIL 6 AM EST WEDNESDAY FOR ANZ330-335-
338-340-345-350-353-355.
&&
$$
