FXUS61 KPHI 251906
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
206 PM EST WED NOV 25 2009
.SYNOPSIS...
LOW PRESSURE OFF THE EAST COAST AND ANOTHER LOW MOVING ACROSS THE
UPPER GREAT LAKES REGION WILL EVENTUALLY COMBINE ACROSS NEW ENGLAND
ON FRIDAY. A STRONG COLD FRONT WILL CROSS THE AREA FRIDAY MORNING.
HIGH PRESSURE WILL BUILD IN OVER THE WEEKEND AND REMAIN FOR MONDAY.
ANOTHER WEATHER DISTURBANCE WILL APPROACH THE AREA NEXT MONDAY
NIGHT.
&&
.NEAR TERM /THROUGH TONIGHT/...
PLENTY OF LOW LEVEL MOISTURE HAS RETURNED TO THE AREA. LOW CLOUDS
AND SOME DRIZZLE WERE OCCURRING AT SOME OF THE OBSERVATION SITES
EARLY THIS AFTERNOON. A VORTICITY MAXIMUM IS SHOWN BY THE GFS TO
APPROACH FROM THE WEST THIS AFTERNOON AND CROSS THE AREA EARLY THIS
EVENING. THIS VORTICITY MAXIMUM AND THE LOW LEVEL MOISTURE WILL
COMBINE TO PRODUCE SCATTERED SHOWERS ACROSS THE AREA FOR THE REST OF
TODAY. A 30 PROBABILITY WAS USED FOR THE FORECAST FOR THE REST OF
THIS AFTERNOON. THE NAM/MET GUIDANCE WAS REJECTED DUE TO ITS
OVER-PRODUCTION OF RAIN IN THIS FIRST FORECAST PERIOD...WHICH
DOESN'T APPEAR TO BE VERIFYING. HIGH TEMPERATURES TODAY WILL RANGE
FROM AROUND 50 OR IN THE LOWER 50S OVER THE NORTH TO THE UPPER 50S
ACROSS THE DELMARVA.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
A BIT OF A LULL TONIGHT AND THE FIRST PART OF THURSDAY AS WE WILL
BE BETWEEN THE FIRST DISTURBANCE AND THE STRONGER ONE EXPECTED TO
MOVE IN FROM THE WEST LATER THURSDAY. A WEAK HIGH PRESSURE AND
RIDGING ALOFT SHOULD ACT TO REDUCE THE COVERAGE OF SHOWERS TONIGHT
FROM SOUTH TO NORTH...AND LITTLE IF ANY SHOWERS ARE EXPECTED EARLY
THURSDAY. CLOUDS WILL STILL BE ABUNDANT ACROSS THE AREA HOWEVER.
SHOWERS WILL INCREASE FROM THE WEST LATER THURSDAY... FOLLOWED BY
POPS RISING TO LIKELY LEVELS THURSDAY NIGHT AND FRIDAY MORNING AS
THE STRONG COLD FRONT CROSSES THE AREA. THE DEEPENING UPPER LOW
AND COLD AIR WITH IT MAY CONTRIBUTE TO SOME ISOLATED CONVECTION
LATE THU NIGHT OF FRI MORNING. NO MENTION OF IT WAS PLACED IN THE
GRIDS AT THIS POINT. WINDY CONDITIONS AND SEASONABLY COOL AIR WILL
BE ACROSS THE AREA FRIDAY WITH THE LIKELY SHOWERS DURING THE
MORNING BECOMING SCT BY AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
THE STRONG LOW PRESSURE SYSTEM WILL MOVE FURTHER NE TOWARD THE
CANADIAN MARITIMES FRIDAY NIGH AS HIGH PRESSURE BUILD IN FROM THE W.
FRIDAY NIGHT INTO EARLY SATURDAY COULD BE QUITE BREEZY DUE TO THE
PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS. THERE COULD ALSO BE SOME
LINGERING SHOWERS EARLY IN THE DAY, BUT CONDS WILL IMPROVE AS THE
HIGH MOVES IN. MOST OF SATURDAY AND ALL DAY SUNDAY LOOK DRY, WITH
TEMPS AROUND NORMAL. THE HIGH BUILDS IN FURTHER ON MONDAY, SO DRY
WX SHOULD CONTINUE.
BY TUESDAY, LOW PRESSURE AND A CDFNT IS EXPECTED TO APPROACH THE
REGION FROM THE S AND W. THERE ARE STILL SOME MDL DIFFS WITH THE
HANDLING OF THESE FEATURES. THE GFS HAS A MUCH STRONGER LOW
EJECTING OUT OF THE SERN CONUS AND MOVG TWD THE APPALACHIANS. THE
ECMWF IS FURTHER E AND WEAKER. SO, WHILE THERE IS DISAGREEMENT ON
THE FEATURES THEMSELVES, THE MDLS AGREE THAT TUESDAY LOOKS WET.
&&
.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
AN UPPER LEVEL TROUGH DIGGING INTO THE GREAT LAKES REGION AND THEN
INTO THE OHIO RIVER VALLEY ON THURSDAY IS PROVIDING A SOUTH TO NORTH
TRACK FOR WEAK STORMS ALONG THE EAST COAST. THE EASTERLY FLOW
PRODUCED AT AND NEAR THE SURFACE BY THESE WEAK STORMS IS PRODUCING
LOW CLOUDS AND DRIZZLE ACROSS MUCH OF THE FORECAST AREA THIS
AFTERNOON, ALONG WITH IFR CONDITIONS, ESPECIALLY ON AND NEAR THE
COASTAL PLAIN. WE EXPECT IFR CONDITIONS TO CONTINUE AT MOST OF OUR
TAF SITES THROUGH THE AFTN HOURS, WITH POSSIBLY A FEW PERIODS OF
MVFR CONDITIONS AS CEILINGS AND/OR VSBYS TEMPORARILY IMPROVE
FROM TIME TO TIME. CONDITIONS MAY BE A LITTLE BETTER AT BOTH ABE AND
RDG GIVEN THEY'RE A LITTLE FURTHER FROM THE COAST, BUT STILL MAINLY
IFR CONDITIONS ARE EXPECTED THERE TOO.
CONDITIONS COULD IMPROVE SLIGHTLY FOR A BRIEF PERIOD THIS EVENING
AS BOTH CEILINGS AND VSBYS COULD RISE TO MVFR CONDITIONS. HOWEVER,
GIVEN THE AMOUNT OF RESIDUAL MOISTURE IN THE AREA, VSBYS COULD
DROP TO 1SM OR LESS IN FOG. THE TAFS INCLUDE THIS PESSIMISTIC
OUTLOOK. NOT THE BEST WEATHER FOR ONE OF THE BUSIEST TRAVEL DAYS
OF THE YEAR.
SOME IMPROVEMENT TO MVFR OR VFR IS EXPECTED LATE THURSDAY MORNING
INTO THURSDAY EVENING AS SLIGHTLY DRIER AIR MOVES IN.
OUTLOOK...
A COLD FRONT IS EXPECTED TO MOVE THROUGH FROM THE NW THURSDAY NIGHT.
BRISK NW WINDS WILL DEVELOP BEHIND THR FRONT. SHOWERS ARE EXPECTED
FRIDAY WITH MVFR AND POSSIBLY IFR CONDITIONS. THERE MAY ALSO BE SOME
SNOW MIXED WITH RAIN SHOWERS MAINLY N/W OF PHL. OVER THE
WEEKEND...VFR CONDITIONS ARE EXPECTED.
&&
.MARINE...
ONSHORE WINDS OF 10 TO 15 KT WILL CONTINUE TODAY, BUT SEAS SHOULD
REMAIN ABOVE 5 FT ON THE OCEAN. THEREFORE THE SMALL CRAFT ADVISORY
WILL REMAIN IN EFFECT ON THE OCEAN.
A TEMPORARY WIND SHIFT TO WEST OR NW SHOULD OCCUR TONIGHT BEFORE
WINDS ONCE AGAIN BECOME NE ON THURSDAY. HOWEVER, WINDS SHOULD STILL
BE RELATIVELY LIGHT. A COLD FRONT FINALLY MOVES THROUGH THE AREA
FROM THE NW THURSDAY NIGHT. THIS WILL ALLOW FOR A SHIFT TO NW THAT
WILL LAST THROUGH THE WEEKEND. ON FRIDAY, THE WINDS WILL INCREASE TO
25 KT AT LEAST IN GUSTS AS WE GET COLDER AIR ON THE WARMER WATERS.
FRIDAY NIGHT INTO SATURDAY STRONGER WINDS ARE EXPECTED AND WE COULD
SEE THE WINDS REACH GALE FORCE ON BOTH THE OCEAN AND DELAWARE BAY.
HIGH PRESSURE IS FORECAST TO MOVE BY TO THE SOUTH OVER THE WEEKEND.
THIS WILL MEAN WINDS SHOULD DECREASE A BIT SATURDAY NIGHT AND EVEN
MORE ON SUNDAY. ON SUNDAY, WINDS MAY EVEN DROP BELOW 25 KT.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
ANZ450>455.
&&
$$
SYNOPSIS...NIERENBERG
NEAR TERM...NIERENBERG
SHORT TERM...NIERENBERG
LONG TERM...IOVINO
AVIATION...MIKETTA
MARINE...MIKETTA
