FXUS61 KPHI 250902
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
402 AM EST WED NOV 25 2009
.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL DIMINISH THIS MORNING. 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 TODAY/...
PLENTY OF LOW LEVEL MOISTURE HAS RETURNED TO THE AREA. LOW CLOUDS
AND SOME DRIZZLE ARE OCCURRING AT THE OBS SITES EARLY TODAY. A
VORT MAX IS SHOWN BY THE GFS APPROACHING FROM THE WEST TODAY AND
CROSSING THE AREA EARLY THIS EVENING. THIS VORT MAX AND THE LOW
LEVEL MOISTURE WILL COMBINE TO PRODUCE SCATTERED SHOWERS ACROSS
MUCH OF THE AREA TODAY. I HAVE USED A 40 POP FOR THE FCST FOR
TODAY SINCE THIS IS OFFERED IN THE 6HR MAV GUIDANCE. THE NAM/MET
GUIDANCE WAS REJECTED DUE TO ITS OVER-PRODUCTION OF RAIN IN THE
FIRST FCST PERIOD...WHICH DOESN'T APPEAR TO BE VERIFYING. HIGH
TEMPERATURES TODAY WILL RANGE FROM THE LOW 50S NORTH TO UPPER 50S
ACROSS THE DELMARVA.
&&
.SHORT TERM /TONIGHT 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 /08Z WEDNESDAY THROUGH SUNDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
TODAY IS A BIG TRAVEL DAY FOR THANKSGIVING. HOWEVER, IT NOW APPEARS
AS THOUGH IFR CONDITIONS WILL DOMINATE TODAY AND COULD HAVE AN
IMPACT ON THE HOLIDAY TRAVEL AND COULD CAUSE AIRPORT DELAYS.
CURRENT TRENDS ARE TO IFR CONDITIONS. LOW CLOUDS FROM THE SOUTH
AND SOUTHEAST WERE STREAMING INTO THE REGION. ALTHOUGH SOME SITES
WERE STILL MVFR/VFR...BY 08Z ALL TAF SITES SHOULD SEE IFR CIGS.
VSBYS WERE 5 MI OR MORE, BUT BY SUNRISE, THE VSBYS SHOULD ALSO
DETERIORATE AS SOME LIGHT RAIN AND DRIZZLE DEVELOP AND VSBY SHOULD
DROP TO 3-4 MI WITH SOME AREAS DROPPING TO 1-2 MI. THE IFR
CONDITIONS ARE THEN FORECAST TO CONTINUE THROUGH THE AFTN WITH
CIGS THE MAIN CULPRIT FOR IFR. HOWEVER, THE LIGHT RAIN AND DRIZZLE
SHOULD DISSIPATE BY LATE AFTN. AFTER DARK, THE CLOUDS MAY BREAK AT
SOME LOCATIONS, BUT IF THEY DO, IFR OR LIFR CIG/VSBY COULD DEVELOP
WITH AREAS OF FOG.
ON THURSDAY...COLD ADVECTION IS FORECAST TO DEVELOP AND CIGS/VSBYS
SHOULD IMPROVE TO VFR DURING THE MORNING.
OUTLOOK...
A COLD FRONT MOVES THROUGH FROM THE NW THURSDAY NIGHT. BRISK NW
WINDS SHOULD DEVELOP BEHIND THE FRONT. ALSO, SHOWERS ARE EXPECTED
ON FRIDAY WITH MVFR AND POSSIBLY IFR CONDITIONS IN THE SHOWERS.
THERE MAY ALSO BE SOME SNOW MIXED WITH RAIN SHOWERS MAINLY N/W OF
PHL. OVER THE WEEKEND...CONDITIONS SHOULD BE VFR.
&&
.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...O'HARA
NEAR TERM...O'HARA
SHORT TERM...O'HARA
LONG TERM...NIERENBERG
AVIATION...STAUBER
MARINE...STAUBER
