FXUS61 KCTP 061545
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1045 AM EST SUN DEC 6 2009
.SYNOPSIS...
HIGH PRESSURE WILL PUSH EASTWARD FROM THE CENTRAL APPALACHIANS AND
OFF THE MID-ATLANTIC COAST ON MONDAY. A WEAK LOW PRESSURE SYSTEM
AND TRAILING FRONTAL BOUNDARY SLIDING THROUGH THE GREAT LAKES AND
OHIO VALLEY MAY BRING SOME LIGHT PRECIPITATION TO THE ALLEGHENIES
LATER MONDAY AND INTO MONDAY NIGHT. HIGH PRESSURE WILL RETURN FOR
TUESDAY BEFORE A STRONG STORM SYSTEM OVER THE CENTRAL U.S. BRINGS
A MIXTURE OF PRECIPITATION THROUGH WEDNESDAY.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
VISIBLE STLT IMAGERY SHOWS LAKE SC AND ISOLD -SHSN BREAKING UP
OVR THE NW MTNS AND LAUREL HIGHLANDS...AS BLYR FLOW BACKS TO THE
SW AND INVERSION HGTS LWR. XPC SC TO CONT TO DEC THRU THE AFTN
WITH SKIES BCMG PARTLY TO MOSTLY SUNNY. SFC HIGH PRES WILL SLIDE
EWD FM WV TWD THE DELMARVA THIS EVE.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH TUESDAY/...
MID-HIGH CLOUDS WORKING IN OVERNIGHT. TEMPS SHOULD RUN NEAR OR
JUST SLIGHTLY BELOW NORMAL...MAINLY IN AREAS WITH FRESH SNOW
COVER. MON/MON NIGHT WILL BRING FLAT FLOW WITH A WEAK VORT MAX
SLIDING ACROSS LAKE ERIE WHICH WILL BRING LGT PRECIP MAINLY
CONFINED TO THE NW MTNS. THEN WEAK ANTI-CYCLONIC FLOW RETURNS FOR
TUE WITH BUILDING E COAST RIDGE AHEAD OF HIGH CONFIDENCE
STORM...THE IMPACT OF WHICH WILL BEGIN TO ARRIVE TUE NIGHT AND
LAST THROUGH MID-WEEK.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
FOCUS IN THE EXTENDED PERIODS RESIDES AROUND HIGH CONFIDENCE MID-
WEEK STORM WHICH MODELS HAVE BEEN ADVERTISING FOR SEVERAL DAYS
NOW. THIS SYSTEMS ULTIMATE IMPACT ON PA HINGES ON WHERE 500MB
TROUGH DEPARTS ROCKIES TUE/WED. PRECIP MOVES IN TUE NGT AS A WEAK
FRONTAL BNDRY LIFTS NORTH AHEAD OF DEEPENING SURFACE LOW WHICH
WILL TRACK NE THROUGH OHIO VALLEY. CENTRAL PA WILL REMAIN ON E
SIDE OF THE LOW...WHICH WILL EVENTUALLY PUSH WARM AIR INTO THE
REGION. BUT TUE NIGHT WHEN PRECIP BEGINS TEMPS SHOULD BE COLD
ENOUGH TO START OFF AS SNOW...AND COULD SEE A COUPLE OF INCHES
ACCUMULATE. BUT WARM AIR WILL STREAK IN AS TEMPS WARM ABV
FREEZING BY 12Z WED IN THE SOUTH AND A COUPLE OF HOURS LATER IN
THE NORTH. HIGH POPS REMAIN JUSTIFIED...AND EVEN BUMPED THEM UP
ANOTHER NOTCH WITH THIS PACKAGE AS QPF FOR THE 18-24 HOUR PERIOD IS
AROUND AN INCH. TROUGH DOES BECOME MORE NEGATIVELY TILTED LATER
WED INTO THU AS A COASTAL LOW FORMS OFF NEW ENGLAND COAST...BUT
ENSEMBLE SUGGESTS SFC VORT SHUD PASS NW OF THE CWA BY THEN.
FLOW REMAINS VERY PROGRESSIVE WITH SEVERAL GEFS MEMBERS ADVERTISING
A 130-150KT 300MB JET THUR/FRI. THIS SHUD PROVIDE A GOOD SCENARIO IN
THE BNDRY LYR FOR LES ACROSS THE NW MTNS/UPSLOPE SNOW FOR LAUREL
HIGHLANDS. 850MB TEMPS CONSIDERABLY COOLER AT -14 TO -16 DEG C
THUR/FRI...WITH A FEW MEMBERS POINTING TOWARDS -16 TO -18 DEG C.
ATTM FEEL GIVEN CONSID CLOUD COVER DURING DAYLIGHT HOURS TEMPS WILL
HOLD IN THE 20S/30S FOR THE END OF THE WEEK...HOWEVER IF SKIES CAN
CLEAR TEMPS WILL EASILY COOL OVERNIGHT.
&&
.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
A FEW LINGERING -SHSN/FLURRIES VCNTY BFD AND MVFR CIGS...MAINLY
ACROSS THE WRN TAF SITES...CONTINUE THIS MORNING WITH WESTERLY
FLOW INTO THE CENTRAL MTNS OF PA. ALL AIRFIELDS SHOULD BECOME VFR
BY LATE MORNING AS HI PRES BUILDS OVER THE REGION.
OUTLOOK...
MON...CHC AFTN SHSN WEST. VFR LIKELY EAST.
TUE...CHC MVFR CIGS WEST. VFR LIKELY EAST.
WED...POTENTIAL RAIN/ICE ALONG WITH IFR CONDS.
THU...STRONG/GUSTY NW WIND.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...RXR/STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...RXR
LONG TERM...BEACHLER/RXR
AVIATION...FITZGERALD/GARTNER
