FXUS61 KCTP 281550
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1050 AM EST SAT NOV 28 2009
.SYNOPSIS...
HIGH PRESSURE BUILDS INTO THE SOUTHERN MID ATLANTIC REGION
THROUGH SUNDAY. EXPECT DRY WEATHER FOR MOST OF THE WEEKEND WITH
INCREASING CLOUDS LATE SUNDAY. A COLD FRONT WILL BRING ANOTHER
CHANCE FOR RAIN AND SNOW SHOWERS SUNDAY NIGHT AND EARLY MORNING.
HIGH PRESSURE THEN BUILDS BACK IN FOR MID-WEEK.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
DOWNSLOPING FLOW KEEPING THE SE HALF OF CWA MO SUNNY. CLEARING
LINE FROM THE WEST ASSOCD WITH THE WARM UP ALOFT IS ALREADY INTO
WRN PA...AND ALMOST TO SOMERSET CO. UPSLOPE FLOW MAY TRY TO KEEP
THE CLOUDS IN LONGER THAN JUST A STRAIGHT EXTRAPOLATION OF THE
CURRENT MOVEMENT OF THE BACK EDGE OF THE CLOUDS. BUT ANY FLURRIES
WILL BE DISSIPATING QUICKLY...MAYBE BEFORE NOON. SO WILL KEEP THEM
OUT OF THE AFTN FCST. MAXES TOUCHING 50F IN THE S ARE PSBL GIVEN
THE 8H TEMPS ABV ZERO AND FULL SUN. ELSEWHERE...PRETTY NORMAL
MAXES TODAY.
&&
.SHORT TERM /7 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 /16Z SATURDAY THROUGH WEDNESDAY/...
BREEZY W/NW WINDS WILL PERSIST THRU 18Z...THEN STEADILY DIMINISH
FROM W-E ACROSS PENN AIRFIELDS. A FEW GUSTS COULD TOUCH
30KTS...HOWEVER MOST WILL FALL WITHIN 20-25KTS WITH ONLY MINOR
IMPACT TO AIRFIELDS. MVFR CIGS WILL IMPROV TO VFR AS AN AREA OF
HIGH PRESSURE STEADILY BUILDS IN FROM THE WEST. FLOW TURNS
WESTERLY THROUGH THE AFTN...WITH CONTINUED DRY AIR. THIS SHUD
ASSIST WITH DOWNSLOPING EFFECT AND FURTHER EROSION OF CLOUDS FOR
SUSQ-VALLEY AIRFIELDS BY MIDDAY. ARND 00Z SUN VFR CONDS SHUD COVER
ALL AIRFIELDS WITH A LGT WESTERLY TRYING TO TURN SOUTHWESTERLY
FLOW. A FEW GUIDANCE MEMBERS SUGGEST PATCHY MVFR CIGS OVERNIGHT
INTO EARLY SUN WITH PSBL FG DEVELOPMENT.
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...DANGELO
SHORT TERM...BEACHLER
LONG TERM...DEVOIR/MARTIN
AVIATION...BEACHLER
