000
FXUS61 KPHI 130516
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1216 AM EST FRI FEB 13 2009

.SYNOPSIS...
INTENSE LOW PRESSURE OFF THE COAST OF MAINE THIS EVENING WILL
CONTINUE TO MOVE NORTHEAST OVERNIGHT. THE STRONG GUSTY WINDS ARE
EXPECTED TO DIMINISH OVERNIGHT. HIGH PRESSURE TO THE NORTH WILL
GENERALLY INFLUENCE THE WEATHER FRIDAY AND OVER THE WEEKEND, BUT A
WEAK STORM WILL PASS WELL TO THE SOUTH SATURDAY AND EARLY SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
STRONG AND GUSTY WINDS WERE CONTINUING TO DIMINISH AROUND
MIDNIGHT. THERE WERE A COUPLE OF GUSTS IN THE MID 30 KNOT RANGE,
AND ONE HIGHER OUTLIER, OTHERWISE GUSTS WERE IN THE PROCESS OF
DIMINISHING AND THE WIND ADVISORY WAS CANCELLED / ALLOWED TO
EXPIRE. SKIES HAVE CLEARED IN THE SOUTH, BUT REMAIN CLOUDY NORTH,
WITH VARIABLE AMOUNTS IN BETWEEN. CLOUDS COULD LINGER OVER THE
SOUTHERN POCONOS MUCH OF THE NIGHT. A SMALL CHANCE OF RAIN AND/OR
SNOW SHOWERS WILL BE IN THE FORECAST THERE ALSO.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
HIGH PRESSURE WILL RIDGE ACROSS THE AREA FRIDAY AND THIS SHOULD
SPELL A DRY FORECAST FOR OUR AREA. A WEAK/DRY COLD FRONT WILL
CROSS THE AREA DURING THE LATE MORNING AND THIS MAY HAVE SOME
CLOUDINESS WITH IT, SO THE DAYTIME FORECAST OF PARTLY CLOUDY
SHOULD SUFFICE. IT WILL BE WINDY ON FRIDAY TOO, BUT NOT TO THE
EXTENT LIKE WAS EXPERIENCED TODAY. WIND GUSTS OF 25 TO 30 MPH CAN
BE EXPECTED, MAINLY DURING THE FIRST PART OF THE DAY. HIGH
TEMPERATURES WILL BE ABOUT 10 DEGREES LOWER THAN TODAY WITH UPPER
30S AND LOW 40S UP NORTH AND MID TO UPPER 40S ACROSS THE
PHILADELPHIA METRO AND DELMARVA AREAS. CONTINUED FAIR WEATHER AND
COOL TEMPERATURES EXPECTED FRIDAY NIGHT WITH MAINLY CLEAR SKIES. 

A LOW PRESSURE SYSTEM IS SHOWN MY THE OPERATIONAL MODELS AS MOVING
FROM THE LOWER OHIO VALLEY FRI NIGHT TO THE VA/NC COAST BY SAT
NIGHT. THIS SYSTEM CONTINUES TO BE SUPPRESSED SOUTHWARD BY THE
MODELS AND ANY CHANCES OF PRECIPITATION THAT WERE IN THE GRIDS
PREVIOUSLY WERE REMOVED WITH MY FORECAST. I HAVE CONTINUED TO
INDICATE MOSTLY CLOUDY OR CLOUDY SKIES FROM SATURDAY AFTERNOON
INTO SATURDAY NIGHT. THE WRF FROM 12Z WAS THE CLOSEST TO BRINGING
ANY PRECIPITATION TO OUR AREA, BUT THE HPC GENERALLY DID NOT USE
IT IN THEIR FORECASTS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
THE WEATHER FOR MUCH OF THE EXTENDED PERIOD LOOKS FAIRLY BENIGN. A 
STORM MAY AFFECT THE AREA TOWARD THE MIDDLE OR END OF NEXT WEEK. 

A ZONAL FLOW ACROSS THE EAST AT THE BEGINNING OF THE PERIOD WILL 
BRING A HIGH PRESSURE SYSTEM FROM THE NORTHERN PLAINS STATES ON 
SUNDAY TO THE MIDDLE ATLANTIC BY TUESDAY. THE HIGH WILL MOVE OFF THE 
EAST COAST WEDNESDAY MORNING. THIS SHOULD BRING A PERIOD OF DRY 
WEATHER WITH SEASONABLE TEMPERATURES. LOWS GENERALLY IN THE 20S WITH 
HIGHS IN THE UPPER 30S OR LOW 40S. DURING THIS PERIOD A LOW PRESSURE 
SYSTEM WILL BE MOVING SOUTH OF OUR AREA. THE TREND WITH THE MODELS 
HAS BEEN TO SUPPRESS ANY PRECIPITATION TO THE SOUTH AND KEEP IT OVER 
THE VA/NC AREA. 

DURING THE MIDDLE OF NEXT WEEK, THE UPPER PATTERN AMPLIFIES AND 
BECOMES PROGRESSIVE. A RIDGE OVER THE AREA TUE EVENING MOVES EAST 
AND IS GIVING WAY TO AN ADVANCING TROUGH. A SFC LOW IS INDICATED BY 
THE 00Z ECMWF AS FORMING OVER THE OHIO VALLEY WED AND MOVING TO OUR 
FORECAST AREA BY 12Z THU. AS AN UPPER LOW DEVELOPS ACROSS THE AREA, 
THE SFC LOW SLOWS JUST TO THE EAST. COULD BE AN INTERESTING PERIOD. 
WE HAVE CHANCE POPS IN THE GRIDS FOR THIS EVENT PRESENTLY, IN LINE 
WITH HPC PRODUCTS.

&&

.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY AND SURROUNDING AREAS.

THE JUST ISSUED TAFS MAINTAIN A VFR FORECAST THROUGHOUT. THE MAIN 
STORY REMAINS THE WIND. STRONG WINDS ARE FORECAST TO CONTINUE OFF 
THE GROUND OVERNIGHT. WHILE SOME DECOUPLING SHOULD OCCUR OVERNIGHT 
WE DID NOT FEEL CONFIDENT ENOUGH TO DROP THE WIND GUSTS IN ANY 
FORECAST PERIOD. WE INCREASED THE GUSTINESS AGAIN ON FRIDAY MORNING 
WHEN THERE SHOULD BE MORE MIXING. WINDS SHOULD THEN START GRADUALLY 
DECREASING AS THE AFTERNOON CONTINUES AND BY FRIDAY EVENING (AS 
DEPICTED IN THE KPHL TAF) BE GONE. 

AS FAR AS THE STRATOCUMULUS DECK GOES, ALL THE FORECAST MODELS 
INCREASE THE MOISTURE FROM NORTH TO SOUTH AS THE NIGHT CONTINUES. 
THIS DOES NOT ALWAYS TRANSLATE INTO CLOUDS, BUT FOR NOW WE DID 
FOLLOW THEIR LEAD. WHILE THE MOST STRATOCUMULUS SHOULD BE AT KRDG 
AND KABE, WE DID BRING IN A STRATOCUMULUS VFR CIG TO ALL THE 
TERMINALS TOWARD FRIDAY MORNING. THEN AS FORECAST MOISTURE BECOMES 
SCANTIER, WE ARE NOT FORECASTING A CIG AT ANY OF THE TERMINALS FROM 
LATE FRIDAY MORNING ONWARD.  
 
OUTLOOK...
HIGH PRESSURE IS EXPECTED TO BUILD IN FROM THE WEST, WITH MAINLY VFR 
CONDITIONS ANTICIPATED FOR SATURDAY, SUNDAY, MONDAY AND TUESDAY.

&&

.MARINE...
STRONG LOW PRESSURE WILL PASS ACROSS CANADA'S ATLANTIC PROVINCES 
FROM TONIGHT INTO FRIDAY BEFORE MOVING OUT OVER THE NORTH ATLANTIC.
THE CIRCULATION AROUND THE LOW WILL MAINTAIN STRONG WEST TO 
NORTHWEST WINDS OVER OUR REGION INTO FRIDAY.  THE STRONGEST WINDS 
OVER OUR MARINE AREA WILL OCCUR TONIGHT AS THE AIR TEMPERATURES 
BEGINS TO DECREASE TO NEAR AND BELOW THE TEMPERATURE OF THE WATER.

HIGH PRESSURE IS FORECAST TO BUILD IN FROM THE WEST FOR THE COMING 
WEEKEND AND FOR THE EARLY PART OF THE NEW WEEK.  WIND SPEEDS ARE 
FORECAST TO REMAIN BELOW 25 KNOTS THROUGH THE PERIOD.

&&

.TIDES/COASTAL FLOODING...
THE STRONG OFFSHORE WINDS WILL LIKELY RESULT IN BLOWOUT TIDES.  
WHILE THERE MAY BE SOME LOW WATER ISSUES AROUND THE TIMES OF LOW 
TIDE THIS EVENING, MORE WIDESPREAD LOW WATER PROBLEMS ARE 
ANTICIPATED AROUND FRIDAY MORNING'S LOW TIDE.

IT IS POSSIBLE THAT THE LOW WATER ADVISORY MAY EVENTUALLY NEED TO
BE EXTENDED INTO FRIDAY EVENING FOR DELAWARE BAY AND FOR THE TIDAL 
DELAWARE RIVER, AS IT MAY TAKE WATER LEVELS A LITTLE LONGER TO 
RECOVER THERE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...LOW WATER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ430-
     431-450>455.
     GALE WARNING UNTIL 10 AM EST THIS MORNING FOR ANZ450>455.
     GALE WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR ANZ430-431.

&&

$$

SYNOPSIS...O'HARA / GIGI / RPW
NEAR TERM.../ RPW / O'HARA
SHORT TERM...O'HARA
LONG TERM...O'HARA
AVIATION...GIGI /IOVINO
MARINE...IOVINO
TIDES/COASTAL FLOODING...IOVINO