FXUS61 KPHI 110150
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
850 PM EST THU DEC 10 2009
.SYNOPSIS...
HIGH PRESSURE WILL GRADUALLY BUILD INTO OUR REGION TONIGHT AND
FRIDAY. THIS HIGH WILL SLIDE TO OUR EAST LATE SATURDAY INTO SUNDAY,
THEN A SOUTHERN TIER LOW PRESSURE SYSTEM MAY HAVE AN IMPACT ON OUR
WEATHER SUNDAY. ANOTHER HIGH PRESSURE SYSTEM BRIEFLY BUILDS IN ON
MONDAY AND TUESDAY BEFORE A COLD FRONT SWINGS THROUGH LATE TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A 01Z SURFACE ANALYSIS PLACED LOW PRESSURE WELL NORTH OF NEW
ENGLAND AND HIGH PRESSURE ACROSS THE TENNESSEE VALLEY. OUR WEATHER
WILL BE DOMINATED BY COLDER AIR BEING ADVECTED INTO OUR AREA
TONIGHT ON A BRISK WESTERLY WIND. THIS WILL PRODUCE RATHER COLD
WIND CHILL VALUES WITH MOST AREAS DOWN INTO THE TEENS EXCEPT THE
SINGLE DIGITS TO NEAR ZERO ACROSS THE FAR NORTHWEST ZONES. AN
ELONGATED SHORT WAVE IS MOVING THROUGH THE NORTHERN PORTIONS OF
OUR CWA THIS EVENING WITH RADAR IMAGERY SHOWING A FEW BANDED TYPE
FEATURES WHICH ARE ORIENTATED MOSTLY PARALLEL TO THE PVA GRADIENT.
THIS APPEARS TO BE MOSTLY FLURRIES, HOWEVER WE CANNOT RULE OUT A
BRIEF SNOW SHOWER WHICH MAY LOCALLY PUT DOWN A LIGHT COATING. AN
UPDATE WAS ISSUED EARLIER TO ADD FLURRIES ACROSS THE NORTH, AND
THESE WILL BE CONTINUED FOR AWHILE LONGER AS THE SHORT WAVE
DEPARTS.
THE WINDS HAVE BEEN BELOW CRITERIA FOR QUITE SOME TIME AND THE
FORECAST SOUNDINGS AS WELL AS MODEL PLAN VIEWS OF THE 925 MB WINDS
INDICATE SPEEDS UP TO 35 KNOTS /THE KDIX DOPPLER RADAR VWP SHOWS
WINDS UP TO 35 KNOTS AS OF 0130Z FROM 3,000 TO 6,000 FEET/. THE
BUFKIT SOUNDINGS INDICATE AN UPPER END OF MOMENTUM TRANSFER,
HOWEVER WE HAVE NOT REALLY BEEN REACHING THAT LEVEL AS THE
LOW-LEVEL THERMAL PROFILE IS NOT QUITE ADIABATIC. GIVEN THAT THE
925 MB WINDS ARE FORECAST TO REMAIN UNDER 40 KNOTS AND THAT WIND
ADVISORY CRITERIA HAS NOT BEEN MET, WE WILL CANCEL THE ADVISORY.
BASED ON THE FORECAST SOUNDINGS/925 MB WINDS, WE WILL GO WITH
GUSTS UP TO 40 MPH AT TIMES TONIGHT.
THE TEMPERATURES AND DEW POINTS WERE ADJUSTED BASED ON THE CURRENT
CONDITIONS AND EXPECTED TRENDS. THE LOW TEMPERATURES OVERALL LOOKED
PRETTY GOOD WITH LITTLE CHANGES MADE ATTM.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
HIGH PRESSURE IS THE DOMINANT WX FEATURE THROUGH THE PERIOD AND
EXPECT COLD CONDITIONS WITH DRY WX THROUGH EARLY SUNDAY. THE WIND
WILL DECREASE ON FRIDAY AND DROP EVEN FURTHER FRIDAY NIGHT AND
VERY LITTLE IN THE WAY OF CLOUDS IS EXPECTED. IT IS POSSIBLE THAT
TEMPS WILL BE COLDER FRIDAY NIGHT THAN TONIGHT, DUE TO BETTER
RADIATIONAL COOLING CONDS, BUT WITH LESS WIND IT WON'T FEEL AS
BAD. BY LATE MORNING OR EARLY AFTN ON SUNDAY, THE HIGH MOVES
FURTHER E. THIS WILL ALLOW MOISTURE ASSOCD WITH A LOW TO THE S AND
ANOTHER LOW OVER THE GRTLKS TO ADVANCE TWD THE REGION. PRECIP
SHOULD BEGIN FROM S TO N AND CONTINUE DURG THE DAY ON SATURDAY AS
THE WK LOW MAKES ITS CLOSEST APPROACH.
THE PRECIP WILL GENLY BE ALL RAIN S AND E OF THE I-95 CORRIDOR,
WITH A WINTRY PRECIP OVER NERN PA AND NRN NJ. ITS ALL ABOUT THE
TEMPS, AND TO USE A FOOTBALL ANALOGY, ITS A GAME OF INCHES. TEMPS
WILL LIKELY WARM ENOUGH DURG THE DAY ON SUNDAY THAT MOST OF THE
COLDER AREAS WILL STILL SEE SOME KIND OF MIXTURE, BUT THEN TEMPS
GET COLD ENOUGH SUNDAY NIGHT THERE COULD BE SOME ADDITIONAL
FREEZING OR FROZEN PRECIP. THE OTHER QUESTION IS HOW MUCH QPF
THERE WILL BE AND THERE IS STILL SOME UNCERTAINTY WHAT THE TEMPS
WILL BE AND HOW MUCH WINTRY PRECIP WILL OCCUR AS A RESULT.
THE LOW IS EXPECTED TO MOVE AWAY FROM THE REGION EARLY MONDAY AND
ANY PRECIP WILL COME TO AN END. TEMPS WILL GET CLOSER TO NORMAL BY
SATURDAY AND SUNDAY, BUT WILL REMAIN BELOW SEASONAL VALUES.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
THE LONG TERM WILL FEATURE TWO DAYS OF ABOVE NORMAL TEMPERATURES ON
MONDAY AND TUESDAY BEFORE TEMPERATURES FALL BELOW NORMAL AGAIN AS
ANOTHER ARCTIC FRONT AND AIR MASS MOVE THROUGH AND INTO THE EASTERN
CONUS ON WEDNESDAY AND THURSDAY.
MONDAY SHOULD BE A BETWEEN SYSTEMS DAY AS THE LOW PRESSURE SYSTEM
DEPARTS OFFSHORE. FORECAST 850MB TEMPS ARE EXPECTED TO BE ABOVE ZERO
AS HIGH AS ABOUT PLUS 8C ON SOME MODELS, SO THIS MIGHT BE THE LAST
RELATIVELY WARM DAY FOR A WHILE AND IF THESE TEMPS ARE GOOD, WE MAY
BE TOO LOW WITH MAX TEMPS.
THE NEXT PCPN CHANCE COMES WITH THE APPROACH AND PASSAGE OF AN
ARCTIC COLD FRONT ON TUESDAY. PRECEDING IT, THE AIR MASS FOR MOST OF
OUR CWA REMAINS WARM ENOUGH THAT A LIQUID PTYPE SHOULD PREVAIL. THE
FORECAST MODELS REMAIN SOMEWHAT MUTED WITH ANY SOUTHERN STREAM
CONTRIBUTION TO THIS SYSTEM AS LOW PRESSURE FORECAST ALONG THE
FRONTAL BOUNDARY STILL ARE WEAK.
AN ARCTIC HIGH PRESSURE SYSTEM THEN BUILDS INTO THE CONUS AND TOWARD
OUR CWA FOR THE REST OF THE LONG TERM. THIS WILL SHUT OFF
PRECIPITATION CHANCES FOR MOST OF OUR CWA. BUT WITH THE GREAT LAKES
WARM AND TOASTY THERE SHOULD BE SOME LAKE EFFECT STREAMERS OR
RESIDUALS THAT REACH US. THE LATEST GFS IS COLDER THAN THE ECMWF ON
WEDNESDAY AND THURSDAY. WE DID SIDE CLOSER TO IT THAN THE LATTER
BECAUSE OF THE SOURCE REGION OF THE HIGH PRESSURE SYSTEM.
BEYOND OUR DETERMINISTIC FORECAST, A PIECE OF THE POLAR VORTEX IS
FORECAST TO GET BLOCKED OVER THE CANADIAN MARITIMES BY A -NAO RIDGE
NOSING INTO GREENLAND. WHILE THE PACIFIC IS FORECAST TO BECOME LESS
HOSTILE FOR COLD, THE BLOCKING RIDGE IS GOING TO PREVENT THE ARCTIC
AIR FROM LEAVING CANADA, A PATTERN THAT SHOULD KEEP US COLDER THAN
NORMAL AS PER THE LATEST PMDHMD.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
THE TAFS CONTINUE WITH THE VFR FORECAST. SOME LAKE EFFECT STRATOCU
THAT MADE INTO THE AREA THIS AFTERNOON SHOULD CONTINUE TO
DISSIPATE THIS EVENING. A WEAK UPPER AIR DISTURBANCE THAT WAS
HELPING IT ALONG WILL MOVE EAST OF THE REGION.
THERE IS STILL A LAKE EFFECT FETCH ON FRIDAY ALTHOUGH MOISTURE IS
FORECAST TO BE LESS. GIVEN WE DID GET A BROKEN VFR CIG AT TIMES
TODAY, WE DECIDED TO GO ONE CATEGORY ABOVE GUIDANCE AND GIVE
MOST TERMINALS A SCATTERED VFR STRATOCU DECK DURING THE DAY BEFORE
DISSIPATING IT TOWARD SUNSET.
AS FAR AS WINDS GO, THEY SHOULD REMAIN RATHER STRONG FROM THE WEST
THROUGH THE TAF FORECAST PERIOD AND THEN DIMINISH A LITTLE TOWARD
AND INTO FRIDAY EVENING. WE HAVE NOT BEEN MIXING WINDS DOWN AS
MUCH AS OUR GUIDANCE HAS BEEN INFERRING, NEVERTHELESS PEAK WIND
GUSTS ON FRIDAY DAY WHEN MIXING SHOULD BE MAXIMIZED BETTER SHOULD
BE INTO THE 30S (KNOTS).
OUTLOOK... AS THE HIGH PRESSURE SYSTEM MOVES OFF TO THE EAST, LOW
PRESSURE ALONG THE MID ATLANTIC COAST COULD BRING LOWERING
CIGS/VSBYS BY SUNDAY EVENING.
&&
.MARINE...
WILL KEEP THE GALE WARNINGS UP SINCE IT ALERTS THOSE PLANNING TO GO
OFFSHORE OR THOSE OFFSHORE PLANNING TO RETURN TO MAKE DECISIONS. IN
ANY EVENT...THE COLDEST AIR BEHIND THE DEEP LOW OF YESTERDAY IS YET
TO ARRIVE BUT WILL DO SO THIS EVENING AND CONTINUE INTO FRIDAY. THE
COLD AIR WILL BRING THE HIGHER WIND SPEEDS DOWN TO THE SURFACE.
THERE ARE SOME GALE FORCE GUSTS RIGHT ON THE BEACH BUT NOT ON THE
OPEN WATERS YET.
WITH THIS TYPE OF A SET-UP THE LOWER DELAWARE BAY IS MUCH ROUGHER
THAN THE OCEAN SIDE WHICH HAS A SMALLER FETCH FOR THE NEARSHORE
WATERS. AS A RESULT...THE WAVES REPORTED NEARSHORE ARE UNDER 2.5
FEET WHILE IN THE DELAWARE BAY CLOSER TO 6 FEET WITH THE LONGER
FETCH DOWN THE BAY. THE WAVE HEIGHTS WILL NOT CHANGE THROUGH THIS
OFFSHORE WIND EVENT INTO THE WEEKEND.
WHAT WE WILL SEE FOR THE FIRST TIME THIS SEASON IS THE FACTOR OF
THE WIND AND TEMPERATURE AND LOWERING WIND CHILLS. OVERNIGHT
TONIGHT AT BUOY 44009 THE WIND CHILL WILL BE IN THE LOWER 20S.
CLOSER TO SHORE WHERE THE LAND TEMPERATURES WILL BE LOWER IT'LL
PROBABLY BE IN THE TEENS. GO TO THE NATIONAL DATA BUOY CENTERS WEB
SITE AND CALL UP THE PARTICULAR BUOY IN MIND AND YOU'LL SEE WHAT
THE WCHILL TEMPERATURE IS.
THE OFFSHORE WINDS AND COLD TEMPERATURES WILL CONTINUE INTO
SATURDAY WITH A TURN TO WARMER CONDITIONS ON SUNDAY BUT AT THE
EXPENSE OF DETERIORATING WEATHER AND A WEAK LOW PRESSURE MOVING
NORTH ALONG THE COAST.
GALES ARE UP FOR THE CANYONS OFF OUR COAST UNTIL SATURDAY. MAKE
SURE YOU CHECK THE OCEAN PREDICTIONS WEB SITE FOR DETAILS.
&&
.TIDES/COASTAL FLOODING...
THE WIND SET UP IS IDEAL FOR LOWERING TIDE LEVELS. SO
ANYONE NAVIGATING THE INTRACOASTAL OR FOR BIGGER SHIPS ROUNDING
THE POINTS...THE TIDES MAY BE ABOUT 1.5 FT BELOW MEAN LOWER LOW
WATER ESPECIALLY GETTING INTO FRIDAY. WINDS PLAY A MAJOR ROLE WITH
THE TIDES...AT THIS TIME ON WEDNESDAY SANDY HOOK WAS NEARLY 4 FT
ABOVE NORMAL AND NOW WE'RE LOOKING AT A NEAR BLOWOUT TIDE. WE
BEGIN ISSUING STATEMENTS FOR NEGATIVE DEPARTURES WHEN THE TIDES REACH
1.8 BELOW MEAN LOWER LOW WATER.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 7 PM EST FRIDAY FOR ANZ450>452.
GALE WARNING UNTIL 3 PM EST FRIDAY FOR ANZ430-431-453>455.
&&
$$
SYNOPSIS...GORSE/NIERENBERG
NEAR TERM...GORSE
SHORT TERM...NIERENBERG
LONG TERM...GIGI
AVIATION...EBERWINE/GIGI
MARINE...EBERWINE
TIDES/COASTAL FLOODING...EBERWINE
