745
FXUS61 KPHI 210050
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
750 PM EST FRI NOV 20 2009
SYNOPSIS
HIGH PRESSURE WILL BUILD ACROSS THE AREA TONIGHT AND SATURDAY. IT
WILL REMAIN IN CONTROL OF THE WEATHER THROUGH THE WEEKEND. LOW
PRESSURE WILL DEVELOP TO THE SOUTH AND MOVE UP ALONG THE EAST
COAST EARLY NEXT WEEK. IT WILL BRING UNSETTLED WEATHER EARLY NEXT
WEEK.
NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
CONDITIONS REMAIN FAVORABLE FOR GOOD RADIATIONAL COOLING TO OCCUR
TONIGHT AS MOST OF THE CLOUD COVER AROUND WILL BE HIGH CLOUDS. LOW
TEMPS WERE LOWERED A BIT ACROSS THE REGION AS TEMPS INTO THE 30S
SEEM LIKELY TO OCCUR. MIN TEMPS WERE RAISED SLIGHTLY AROUND
PHILADELPHIA AND SHOULD BE CLOSER TO 40 OVERNIGHT.
SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/
FAIR WEATHER WITH SEASONABLE TEMPERATURES WILL CONTINUE SATURDAY
AND SUNDAY AS THE HIGH CRESTS OVER THE AREA. HIGHS BOTH DAYS WILL
BE IN THE 50S FOR THE MOST PART...WITH LOWS IN THE 30S.
FCST MODELS SHOWING DIFFERING SOLUTIONS WITH REGARDS TO WEAK LOW
PRESSURE DEVELOPING ALONG THE SOUTHEAST COAST AND MOVING NORTHEAST
LATER SUNDAY AND MONDAY. THE SYSTEM DOES NOT APPEAR TO BECOME VERY
STRONG, BUT IT DOES SEND ENOUGH MOISTURE ACROSS THE AREA FOR
LIKELY POPS FOR THE REGION ON MONDAY. QPF TOTALS WILL MOST LIKELY
BE 1/2 INCH OR SO.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
FOLLOWING TRENDS FROM HPC WHICH GENERALLY WENT WITH THE ECMWF SHOWED
LOW PRESSURE MOVING AWAY FROM THE AREA LATE MONDAY NIGHT WITH HIGH
PRESSURE IN EASTERN CANADA EXTENDING SOUTH OVER THE REGION. THIS
SHOULD MEAN DRYING TRENDS LATE MONDAY NIGHT WITH A DRY DAY ON
TUESDAY. TUESDAY NIGHT AND WEDNESDAY WILL SEE ANOTHER FRONT FROM THE
WEST MOVE EAST. THIS FRONT SHOULD CROSS THE REGION WEDNESDAY AFTN.
WITH THE WARM ADVECTION AHEAD OF THE FRONT LATE TUESDAY NIGHT COULD
SEE SOME RAIN AND SHOWERS ARE POSSIBLE DURING THE DAY WEDNESDAY.
FOR THANKSGIVING, AN UPPER TROUGH DIGS INTO THE WESTERN GREAT LAKES.
WE HAVE WARM ADVECTION OVER THE AREA AND DUE TO THIS COMBINATION THE
FORECAST WILL INCLUDE A CHANCE OF SHOWERS.
THURSDAY NIGHT, A STRONG COLD FRONT MOVES THROUGH FROM THE NW AND WE
GET INTO A COLD ADVECTION PATTERN FOR FRIDAY WITH CYCLONIC FLOW
ALOFT AND VERY COOL TEMPERATURES ON FRIDAY. OVER THE FAR NORTHERN
ZONES, THERE IS A CHANCE OF RAIN OR SNOW SHOWERS ON FRIDAY.
HPC TEMPS ARE GENLY REASONABLE.
AVIATION /01Z SATURDAY THROUGH WEDNESDAY/
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
NORTHWEST WINDS GUSTING UP TO 25 KT IN A FEW LOCATIONS ARE EXPECTED
TO SUBSIDE TOWARD EVENING, THEN REMAIN IN THE 5 TO 10 KT RANGE
DURING THE OVERNIGHT HOURS AND ON SATURDAY. A HIGH BKN DECK FORMED
OVER THE NORTHERN TAF SITES BEFORE NOON, WITH A SCT DECK IN THE
SOUTH. THESE CLOUDS ARE EXPECTED TO DISSIPATE ONCE THE SUN GOES
DOWN. BASICALLY VFR CONDITIONS EXPECTED THROUGH A GOOD PART OF THE
UPCOMING WEEKEND.
OUTLOOK...
DRY WEATHER IS EXPECTED INTO EARLY SUNDAY. A CHANCE OF RAIN RETURNS
FOR LATE SUNDAY INTO MONDAY AS LOW PRESSURE MOVES NORTH ALONG THE
MID ATLANTIC COAST.
MARINE
WITH SEAS AROUND 4.5 FT AND WIND GUSTS IN THE 20 TO 25 KT RANGE, SCA
CONDITIONS ARE BARELY BEING REACHED OVER THE OCEAN WATERS. WITH
CONDITIONS EXPECTED TO IMPROVE TOWARD EVENING, THE SCA IN EFFECT
UNTIL 4PM THIS AFTERNOON WILL BE ALLOWED TO EXPIRE BOTH ON THE OCEAN
AND DELAWARE BAY.
HIGH PRESSURE FROM THE WEST IS FORECAST TO BUILD ACROSS OUR REGION
TONIGHT AND SATURDAY, THEN MOVE OFF TO THE EAST ON SUNDAY. LOW
PRESSURE IS THEN EXPECTED TO MOVE NORTH ALONG OR NEAR THE COAST
SUNDAY AND MONDAY. RIGHT NOW THIS LOW LOOKS RELATIVELY WEAK. THE
STRONGEST ONSHORE WINDS (30KT OR SO) WILL LIKELY OCCUR LATE SUNDAY
NIGHT INTO MONDAY MORNING, THEN SUBSIDE AGAIN MONDAY AFTERNOON AND
EVENING. MORE HIGH PRESSURE IS EXPECTED TUESDAY AND WEDNESDAY.
TIDES/COASTAL FLOODING
TIDAL ANOMALIES WITH THE WEAK LOW PRESSURE SYSTEM EXPECTED ON SUNDAY
AND MONDAY LOOK TO BE AROUND 1 FOOT. WE'LL BE BETWEEN NEW MOON AND
FULL MOON, SO THE ASTRONOMICAL TIDES ARE FAIRLY LOW. UNDER NORMAL
CIRCUMSTANCES, THIS WOULDN'T POSE ANY PROBLEMS, BUT WITH ANTECEDENT
CONDITIONS BEING WHAT THEY ARE FROM LAST WEEK'S STORM, WE'LL BE
KEEPING AN EYE ON THE SITUATION.
PHI WATCHES/WARNINGS/ADVISORIES
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
SYNOPSIS...O'HARA
NEAR TERM...MEOLA
SHORT TERM...O'HARA
LONG TERM...STAUBER
AVIATION...MIKETTA
MARINE...MIKETTA
TIDES/COASTAL FLOODING...MIKETTA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page