FXUS61 KPHI 070855
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
355 AM EST MON DEC 7 2009

.SYNOPSIS...
HIGH PRESSURE WAS PASSING OFF THE MIDDLE ATLANTIC COAST EARLY
THIS MORNING. A DRY COLD FRONT FROM THE WEST IS FORECAST TO ARRIVE
TONIGHT WITH ANOTHER AREA OF HIGH PRESSURE FOLLOWING FOR TUESDAY.
STRONG LOW PRESSURE FROM THE SOUTHWEST IS EXPECTED TO PASS ACROSS
THE GREAT LAKES ON WEDNESDAY, WITH A SECONDARY LOW DEVELOPING
ALONG THE MIDDLE ATLANTIC COAST. THE COMPLEX LOW SHOULD MOVE UP
INTO EASTERN CANADA ON THURSDAY, ALLOWING HIGH PRESSURE TO BUILD
INTO OUR REGION FROM THE WEST FOR THE END OF THE WORK WEEK.
ANOTHER COLD FRONT MAY ARRIVE ON SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AT 3:30 AM, HIGH CLOUDS COVERED OUR REGION AND TEMPERATURES WERE
MAINLY IN THE 20S AND LOWER 30S. WE WILL EXTEND THE SPECIAL
WEATHER STATEMENT CONCERNING ICY ROADS AND WALKWAYS IN MUCH OF
EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY UNTIL 9:00 AM.

IT APPEARS AS THOUGH THE HIGH CLOUDS MAY THIN A BIT DURING THE
DAYLIGHT HOURS. TEMPERATURES TODAY ARE FORECAST TO BE A TAD BELOW
NORMAL.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
AN UPPER LEVEL SHORT WAVE WAS LOCATED OVER THE MIDDLE MISSISSIPPI
RIVER VALLEY EARLY THIS MORNING. THE FEATURE IS EXPECTED TO PASS
ACROSS THE NORTHEASTERN STATES THIS EVENING, PULLING A DRY COLD
FRONT THOUGH OUR REGION.

ANOTHER AREA OF HIGH PRESSURE FROM THE WEST IS FORECAST TO BUILD
INTO THE NORTHEASTERN STATES ON TUESDAY AND IT SHOULD BEGIN TO
PUSH UP INTO EASTERN CANADA ON TUESDAY NIGHT.

THE GUIDANCE HAS BEEN FAIRLY CONSISTENT IN HANDLING THE STRONG
LOW APPROACHING FROM THE WEST. IT CONTINUES TO APPEAR AS THOUGH
THE PRIMARY SURFACE LOW WILL PASS NEAR CHICAGO EARLY ON WEDNESDAY
MORNING, WITH A SECONDARY LOW DEVELOPING OVER THE CHESAPEAKE BAY
REGION. BOTH SYSTEMS ARE EXPECTED TO LIFT TO THE NORTHEAST ON
WEDNESDAY AND WEDNESDAY NIGHT.

PRECIPITATION WILL LIKELY BEGIN TO SPREAD INTO OUR REGION FROM
THE SOUTHWEST ON TUESDAY NIGHT. THERE SHOULD BE ENOUGH COLD AIR IN
PLACE IN PARTS OF EASTERN PENNSYLVANIA AND NORTHERN NEW JERSEY TO
RESULT IN A PERIOD OF WINTRY PRECIPITATION. WE WILL SIMPLY MENTION
SNOW AND RAIN AT THIS POINT. HOWEVER, SOME ICE IS ALSO POSSIBLE.
FOR THE CITY OF PHILADELPHIA, THE UPPER DELMARVA AND SOUTHERN AND
CENTRAL NEW JERSEY, THE PRECIPITATION SHOULD BE MOSTLY RAIN
THROUGH THE ENTIRE EVENT.

WITH THE HIGH CONTINUING TO MOVE FARTHER AWAY TO OUR NORTHEAST
AND WITH SOME FAIRLY STRONG LOW LEVEL WINDS FROM THE SOUTHEAST AND
SOUTH, THE NEAR AND BELOW FREEZING AIR SHOULD BE SCOURED OUT OF
OUR REGION ON WEDNESDAY MORNING. AS A RESULT, ALL LOCATIONS ARE
EXPECTED TO EXPERIENCE RAIN FROM THE MID MORNING HOURS INTO THE
AFTERNOON ON WEDNESDAY.

DRY AIR IS FORECAST TO BEGIN PUSHING UP INTO OUR REGION FROM THE
SOUTHWEST ON WEDNESDAY AFTERNOON.

TEMPERATURES ON WEDNESDAY ARE ANTICIPATED TO BE QUITE VARIED
ACROSS OUR REGION. WHILE THE POCONOS AND SUSSEX COUNTY, NEW JERSEY
MAY NOT GET OUT OF THE 30S, SUSSEX COUNTY IN DELAWARE MAY BE NEAR
60 DEGREES IN THE AFTERNOON.

OUR WET AUTUMN LOOKS TO BE SPILLING OVER INTO METEOROLOGICAL
WINTER. WE MAY SEE LIQUID PRECIPITATION AMOUNTS IN EXCESS OF ONE
INCH IN MUCH OF OUR REGION FROM TUESDAY NIGHT INTO WEDNESDAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
WE WILL CONTINUE TO KEEP THE LONG TERM PERIOD OF THE FORECAST
MAINLY DRY AS HIGH PRESSURE BUILDS INTO OUR REGION FROM THE WEST
FOR THURSDAY AND FRIDAY. A COLD FRONTAL PASSAGE REMAINS POSSIBLE
FOR SATURDAY.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

HIGH PRESSURE OVER THE MID ATLANTIC REGION WILL MOVE OFF TO THE
EAST TODAY. MID AND HIGH CLOUDS SPREAD ACROSS OUR AREA LATE SUNDAY
AND WILL CONTINUE TODAY. CONDITIONS WILL BE VFR ALTHOUGH VSBYS
COULD APPROACH MVFR IN SOME LIGHT FOG IN A FEW LOCATIONS AROUND
DAYBREAK THIS MORNING. LIGHT WINDS WILL BECOME S TO SW 5 TO 10 KT
TODAY. A WEAK AREA OF LOW PRESSURE WILL MOVE ACROSS TO OUR NORTH
TONIGHT DRAGGING AN EQUALLY WEAK FRONTAL ZONE ACROSS OUR REGION.
THIS WILL ALLOW ANOTHER AREA OF HIGH PRESSURE TO PUSH IN FROM THE
WEST LATE TONIGHT INTO TUESDAY. WINDS WILL SWING AROUND TO W EARLY
TONIGHT AND NW AFTER MIDNIGHT. AS THE HIGH PRESSURE MOVES IN,
SKIES WILL BEGIN TO CLEAR. VFR CONDITIONS WILL CONTINUE THROUGH
THE NIGHT.

OUTLOOK...
THE HIGH PRESSURE SYSTEM WILL MOVE ACROSS OUR AREA TUESDAY AND
SLIDE OFF TO OUR EAST EARLY TUESDAY NIGHT. AS THE HIGH MOVES OFF,
A STRONG LOW PRESSURE SYSTEM WILL MOVE IN FROM THE SOUTHWEST AND
WEST LATE TUESDAY NIGHT AND WEDNESDAY. THE MAIN STORM CENTER IS
FORECAST TO MOVE NORTHEAST ACROSS THE GREAT LAKES WITH A WEAK
SECONDARY LOW CROSSING OUR AREA WEDNESDAY. RAIN AND WINDY
CONDITIONS WILL ACCOMPANY THIS SYSTEM WITH REDUCED CIGS AND VSBYS.
SOME SNOW OR MIXED PRECIPITATION COULD OCCUR IN OUR NORTHERN AREAS
AT THE ONSET TUESDAY NIGHT. THE RAIN WILL END AND CONDITIONS WILL
BEGIN TO IMPROVE WEDNESDAY NIGHT AS THE LOWS MOVE OFF TO THE NORTH
AND NORTHEAST. HIGH PRESSURE PUSHING IN FROM THE WEST WILL BRING
FAIR WEATHER WITH VFR CONDITIONS THURSDAY THROUGH FRIDAY.

&&

.MARINE...
HIGH PRESSURE OVER THE MID ATLANTIC REGION HAS ALLOWED WINDS AND
SEAS TO DROP BELOW SMALL CRAFT ADVISORY LEVELS. THE HIGH WILL
DRIFT OFF TO THE EAST TODAY. A WEAK AREA OF LOW PRESSURE WILL MOVE
ACROSS TO OUR NORTH TONIGHT DRAGGING AN EQUALLY WEAK FRONTAL ZONE
ACROSS OUR REGION. ANOTHER HIGH PRESSURE SYSTEM WILL MOVE IN LATE
TONIGHT INTO TUESDAY AND THEN HEAD OFF TO THE EAST TUESDAY NIGHT.
WINDS AND SEAS THROUGH THIS TIME PERIOD WILL REMAIN BELOW ADVISORY
CRITERIA. A STRONG LOW PRESSURE SYSTEM WILL THEN MOVE IN FROM THE
SOUTHWEST AND WEST LATE TUESDAY NIGHT AND WEDNESDAY. THE MAIN
STORM CENTER IS FORECAST TO MOVE NORTHEAST ACROSS THE GREAT LAKES
WITH A WEAK SECONDARY LOW CROSSING OUR AREA WEDNESDAY. WINDS ARE
EXPECTED TO INCREASE, ALTHOUGH IF THE SECONDARY LOW DOES INDEED
DEVELOP AND IS OVER OUR AREA, THE WINDS MAY BE LIGHTER FOR A TIME.
OVERALL, WINDS FROM THE EAST THEN SOUTHEAST ARE FORECAST TO
INCREASE WEDNESDAY, WITH AN EVENTUAL SHIFT TO THE SOUTH AND
SOUTHWEST. THERE IS WARMER AIR FORECAST TO SURGE NORTHWARD AHEAD
OF THE SYSTEM, THEREFORE THAT WOULD HINDER DEEPER VERTICAL MIXING.
THE LOWS ARE FORECAST TO MOVE OFF TO THE NORTH AND NORTHEAST
WEDNESDAY NIGHT. COLDER AIR WILL THEN ARRIVE ALLOWING DEEPER
MIXING TO OCCUR. WINDS ARE EXPECTED TO REACH ADVISORY LEVELS AND
POSSIBLY EVEN GALE FORCE LATE TUESDAY NIGHT AND CONTINUE INTO
THURSDAY NIGHT. HIGH PRESSURE MOVING IN FROM THE WEST WILL BRING A
RETURN TO MORE TRANQUIL CONDITIONS BY LATE FRIDAY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...IOVINO
NEAR TERM...IOVINO
SHORT TERM...IOVINO
LONG TERM...IOVINO
AVIATION...RPW
MARINE...RPW