FXUS61 KPHI 110801
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
301 AM EST FRI DEC 11 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH SATURDAY AND THEN
MOVE OFFSHORE. LOW PRESSURE FROM THE GULF COAST STATES WILL
INTENSIFY AS IT MOVE TO THE NORTHEAST. IT SHOULD MOVE BY TO THE EAST
SUNDAY EVENING. HIGH PRESSURE WILL BUILD BACK IN BEHIND THE LOW
MONDAY. ANOTHER FRONTAL SYSTEM SHOULD AFFECT THE AREA TUESDAY
FOLLOWED BY HIGH PRESSURE FOR THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
COLD HIGH PRESSURE FROM THE WEST WILL CONTINUE TO BUILD ACROSS THE
AREA. IT WILL BE WINDY TODAY AND WINDS AT 925 MB SUGGESTS WIND
GUSTS INTO THE 30S TODAY, BUT NOT QUITE ENOUGH FOR AN ADVISORY.
WITH WEAK SHORT WAVES MOVING THROUGH ALOFT, SOME FLURRIES ARE
POSSIBLE NORTH, OTHERWISE, SKIES WILL BE PARTLY CLOUDY THERE AND
MOSTLY SUNNY SOUTH. MET TEMPS LOOK BEST BASED ON SOUNDINGS AND LOW
LEVEL THICKNESSES.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
HIGH PRESSURE WILL CONTINUE TO BUILD TO THE EAST, ALLOWING THE
WINDS TO SLOWLY DIMINISH, WITH WINDS ON SATURDAY GENERALLY 10 TO
15 MPH. WE COULD SEE SOME FLURRIES LINGER NORTH TONIGHT, BUT WITH
THE HIGH OVER THE AREA SATURDAY, SKIES WILL BE SUNNY/MOSTLY SUNNY.
MET TEMPS AGAIN LOOK BEST.
SATURDAY NIGHT THE HIGH MOVES OFF TO THE EAST. MEANWHILE, THE
UPPER RIDGE LINE ALSO MOVES OFF TO THE EAST. THIS SHOULD MEAN AN
INCREASE IN MID AND HIGH CLOUDS AT NIGHT. MAV/MET BLEND WAS USED
FOR TEMPS.
SUNDAY AND SUNDAY NIGHT, LOW PRESSURE FROM THE SOUTHEAST
INTENSIFIES SLOWLY AS IT MOVES TO THE NORTHEAST. THE GFS/NAM ARE
SLOWER IN TIMING THAN THE UKMET/ECMWF WHICH START PCPN EARLIER. I
WENT WITH THE UKMET/ECMWF SOLUTION SINCE THE NAM TENDS TO BE SLOW
AND LESS RELIABLE LONGER RANGE ANYWAY. ALL GUIDANCE SUGGESTS SOME
SNOW IS POSSIBLE AT THE ONSET TO THE N/W OF PHL WITH ALL PCPN
PROBABLY CHANGING TO RAIN, THEN THE POSSIBILITY OF THE RAIN
TURNING BACK TO SNOW NORTH BEFORE ENDING LATE. SINCE MODELS HAVE
ALL LINED UP WITH THIS EVENT, AT LEAST FOR PCPN SUNDAY, POPS HAVE
BEEN RAISED TO CATEGORICAL SUNDAY. HOWEVER, SUNDAY NIGHT, POPS
WERE KEPT CHC DUE TO TIMING CONCERNS. MEX TEMPS LOOKED REASONABLE.
&&
.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 /08Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
HIGH PRESSURE PUSHING IN FROM THE WEST WILL PROVIDE GOOD FLYING
WEATHER WITH VFR CONDITIONS THROUGH SATURDAY NIGHT. THE WIND WILL
CONTINUE TO BE THE BIGGEST CONCERN TODAY AS GUSTS REACH THE 30 TO
35 KT RANGE. THE GUSTINESS WILL DIMINISH TONIGHT.
OUTLOOK...
THE HIGH WILL REACH OUR AREA SATURDAY AND THEN BEGIN TO PUSH OFF
TO THE EAST SATURDAY NIGHT. LOW PRESSURE ALONG THE MID ATLANTIC
COAST COULD BRING LOWERING CIGS/VSBYS SUNDAY INTO SUNDAY NIGHT.
HIGH PRESSURE WILL RETURN MONDAY AND MONDAY NIGHT BEFORE A COLD
FRONT APPROACHES FROM THE WEST ON TUESDAY
&&
.MARINE...
GALE WARNINGS WILL REMAIN IN EFFECT TODAY AS W WINDS CONTINUE TO
GUST TO BETWEEN 35 AND 40 KT. WINDS WILL BE DIMINISHING DURING
THE EVENING AND OVERNIGHT HOURS. WILL DROP THE GALE WARNINGS ON
DELAWARE BAY AND ON OUR OCEAN WATERS SOUTH OF GREAT EGG INLET AT
7 PM. THE WINDS WILL DIMINISH A LITTLE LATER ON OUR OCEAN WATERS
NORTH OF GREAT EGG INLET, SO THE WARNING THERE WILL REMAIN UP
UNTIL 4 AM. AS THE HIGH PRESSURE SYSTEM MOVES IN SATURDAY AND
SATURDAY NIGHT, RATHER TRANQUIL CONDITIONS WILL PREVAIL. WINDS
AND SEAS COULD APPROACH OR REACH ADVISORY CONDITIONS ONCE AGAIN
LATE SUNDAY AND SUNDAY NIGHT AS LOW PRESSURE MOVES ALONG THE MID
ATLANTIC COAST.
&&
.TIDES...
THE OFFSHORE WINDS ARE NOW HAVING A BIG INFLUENCE ON WATER LEVELS.
HEIGHTS EARLY THIS MORNING WERE RUNNING 1/2 TO 1 FOOT BELOW
NORMAL. DEVIATIONS WILL CONTINUE TO DROP TO 2 FEET OR MORE BELOW
IN SOME LOCATIONS. FOR THIS REASON A LOW WATER ADVISORY HAS BEEN
ISSUED ALONG OUR OCEAN FRONT AND ON DELAWARE BAY FOR THE NEXT 2
LOW TIDE CYCLES. THESE WILL OCCUR THIS MORNING AND THIS EVENING.
MARGINAL LEVELS WITH NEAR BLOWOUT CONDITIONS ARE EXPECTED THIS
MORNING. EVEN LOWER LEVELS ARE EXPECTED WITH THE EVENING LOW
TIDE WITH BLOWOUT CONDITIONS EXPECTED IN MOST LOCATIONS. FOR NOW,
THE LOW WATER ADVISORY WILL BE IN EFFECT FROM 7 AM THIS MORNING
TO 3 AM EARLY SATURDAY MORNING. IT MAY NEED TO BE EXTENDED ONE
MORE LOW TIDE CYCLE, BUT WE HAVE PLENTY OF TIME TO DECIDE THAT.
FARTHER UP ON THE LOWER DELAWARE RIVER, IT WILL TAKE A LITTLE
LONGER FOR WATER LEVELS TO DROP. BUT EVEN THERE, BY EARLY
SATURDAY MORNING, LEVELS COULD BE APPROACHING LOW WATER CRITERIA.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...LOW WATER ADVISORY FROM 7 AM THIS MORNING TO 3 AM EST SATURDAY
FOR ANZ430-431-450>455.
GALE WARNING UNTIL 4 AM EST SATURDAY FOR ANZ450>452.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR ANZ430-431-
453>455.
&&
$$
SYNOPSIS...STAUBER
NEAR TERM...STAUBER
SHORT TERM...STAUBER
LONG TERM...GIGI
AVIATION...RPW
MARINE...RPW
TIDES...RPW
