FXUS61 KCTP 280926
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
426 AM EST SAT NOV 28 2009
.SYNOPSIS...
HIGH PRESSURE BUILDS INTO THE SOUTHERN MIDDLE ATLANTIC REGION FOR
THE WEEKEND. DRY WEATHER FOR MOST OF THE WEEKEND WITH INCREASING
CLOUDS SUNDAY. A COLD FRONT WILL BRING ANOTHER CHANCE FOR RAIN
AND SNOW SHOWERS LATE SUNDAY AND MONDAY. HIGH PRESSURE THEN
BUILDS BACK IN FOR MID-WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
FOCUS FOR TODAY IS DEPARTING 500MB TROUGH AXIS AND INCREASING
HEIGHTS...WHICH WILL ASSIST WITH CUTTING OFF UPSLOPE MECHANISM AND
SHSN FOR LAURELS. IR IMAGERY INDICATES A CLEARING LINE OF CLOUDS
EXTENDING FROM NW LOWER MI STRETCHING SE THRU CENTRAL WV. HEIGHTS
CONTINUE TO RISE...WITH SFC PRESSURE RISES ARND 2-3MB/3HR. THIS SHUD
ALLOW W/NW BLUSTERY CONDS TO PERSIST THIS MORNING...WITH 20-30MPH
GUSTS. BY 18Z PRESSURE RISES BEGIN TO STABILIZE AS NORTHERN
PERIPHERY OF SFC RIDGE PUSHES INTO CENTRAL PA. MID-LVL FLOW TURNS
WESTERLY...BUT SHUD REMAIN PROGRESSIVE. DOWNSLOPING EFFECT WILL
CONTINUE FOR THE SUSQ-VALLEY...COUPLED WITH MAXIMIZED SUBSIDENCE AND
SKIES SHUD BECOME SUNNY. UPSTREAM FOR THE ALLEGHENIES WEAK UPSLOPE
AND LINGERING MOISTURE WILL HOLD CLOUDS THRU MIDDAY...THEN THIN LATE
THIS AFTN. WEAK 850MB THERMAL TROUGH QUICKLY DEPARTS...SO TEMPS SHUD
NOT BE TOO COOL M30-U30S ACROSS THE NW MTNS/LAURELS. ELSEWHERE TEMPS
WILL WARM INTO THE L40 CENTRAL...AND M40S TO A FEW U40S ACROSS LOWER
SUSQ-VALLEY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
SFC RIDGE HOLDS ACROSS THE SOUTHERN MID-ATLANTIC REGION...AS 500MB
FLOW TURNS WESTERLY. WEAK SUBSIDENCE SHUD DRY BNDRY LYR FURTHER
PUSHING DEW PTS INTO THE 20S THIS EVE. ENSEMBLE GUIDANCE SUGGESTS
925MB TEMPS WARM BY 06Z TO ARND 2 DEG C...WITH TYPICAL THERMAL
TROUGH PERSISTING ALONG LEE-SIDE OF THE ALLEGHENIES. RADIATIONAL
COOLING SHUD BE MAXIMIZED EARLY WITH A THIN CLOUD SHIELD
OVERHEAD...THEN AS FLOW TURNS SWSTRLY TEMPS SHUD SLOW THEIR COOLING
RATES. OVERALL EXPECT M20S ACROSS NORTHERN TIER...L30S FOR REMAINDER
OF CWFA. A FEW ENSEMBLE MEMBERS SUGGEST MID-LVL MOISTURE POOLING
EAST INTO THE NW MTNS BY 12Z SUN...HOWEVER FEEL THIS MAY BE TOO
AGGRESSIVE. HAVE OPTED TO JUST MARGINALLY INCREASE CLOUDS AFT 06Z
FOR THE NW CWFA.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
A RATHER CHANGEABLE WEEK IS IN STORE WITH TWO PERIODS OF DISTURBED
WEATHER EXPECTED TO AFFECT CENTRAL PA AND CORRESPONDING
TEMPERATURE FLUCTUATIONS.
SUNDAY STARTS TRANQUIL WITH WEAK SURFACE RIDGE GIVING WAY TO AN
INTENSIFYING COLD FRONT PUSHING EASTWARD FROM THE OHIO VALLEY.
THIS SHOULD SPREAD RAIN THEN SNOW SHOWERS ACROSS THE AREA LATE
SUNDAY FOLLOWED BY ANOTHER SHORT LIVED LAKE EFFECT SNOW SHOWER
REGIME MONDAY INTO TUESDAY.
UNCERTAINTY REGARDING THE STRENGTH AND TIMING OF POTENTIAL MID TO
LATE WEEK STORMINESS PERSISTS AS PER LATEST MEDIUM RANGE MODELS
AND ENSEMBLES. SOUTHWESTERN U.S. CUTOFF IS EXPECTED TO EJECT INTO
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER VALLEY ON TUESDAY
WHILE A POLAR DISTURBANCE TRACKS THROUGH THE UPPER MIDWEST AND
INTO THE WESTERN GREAT LAKES. DETERMINISTIC SOLUTIONS DEVELOP A
RATHER FAST MOVING AND INTENSIFYING SFC LOW WITH CONSENSUS TRACK
FROM THE GULF COAST REGION NEWD THROUGH THE MID ATLANTIC REGION
WEDNESDAY REACHING NEWFOUNDLAND ON THURSDAY...WITH A FAIRLY
HOMOGENEOUS COLD AIR MASS COVERING THE EASTERN THIRD OF THE
COUNTRY IN ITS WAKE FOR FRIDAY INTO EARLY SATURDAY.
NOTED UNCERTAINTY IN TIMING OF PRECIPITATION ON WEDNESDAY AND
PTYPE WED NIGHT AND THURSDAY AND WILL CONTINUE TO BROADBRUSH
RAIN/SNOW CHANCES UNTIL CONFIDENCE IMPROVES OVER THE NEXT FEW
DAYS.
&&
.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
CONSIDERABLE LLVL MOISTURE INDICATED AS MVFR PATCHY IFR CIGS.
BLUSTERY W/NW CONDS WILL PERSIST THRU THE OVERNIGHT...WITH
25-35KTS. SHSN WILL BEGIN TO TAPER OFF BY 10Z TO ISO SHSN FOR
BFD/JST/AOO/UNV. EXPECT IFR CONDS TO LINGER FOR JST AND VICINITY
OF AOO...WHILE BFD/UNV SHUD IMPROV BY 13Z TO MVFR CIGS/VSBYS.
DOWNSTREAM AT MDT LESS CLOUDS FROM WEAK DOWNSLOPING
EFFECT...HOWEVER IPT WILL SEE PATCHY MVFR CIGS. GUSTY W/NW WINDS
WILL PERSIST AFT 13Z...HOWEVER MORE IN THE 20-30KT RANGE AND
GRADUALLY DIMINISH AND BECOME WESTERLY BY 18Z. CIGS SHUD IMPROVE
FOR MOST AIRFIELDS TO VFR CONDS BY 00Z SUN...ALTHOUGH GUIDANCE
SUGGESTS PSBL FG DEVELOPMENT EARLY SUN.
OUTLOOK...
SUN...VFR.
MON...MVFR CIGS/VIS IN SHRA.
TUE...IFR/MVFR W IN POST FRONTAL SHRA. VFR E.
WED...VFR.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...BEACHLER
NEAR TERM...BEACHLER
SHORT TERM...BEACHLER
LONG TERM...DEVOIR/MARTIN
AVIATION...BEACHLER
