FXUS61 KCTP 261945
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
245 PM EST SAT DEC 26 2009
.SYNOPSIS...
LOW PRESSURE WILL TRACK NORTHEASTWARD AND OFF OF THE NEW JERSEY
COAST BY EARLY SUNDAY...TAKING MOST OF THE LINGERING RAINFALL AND
DRIZZLE WITH IT. ON THE BACKSIDE OF THIS STORM...COLDER AIR WILL
OVERSPREAD WESTERN AND CENTRAL PORTIONS OF THE STATE BY MORNING...
WITH FLURRIES AND LAKE EFFECT SNOW SHOWERS ACCOMPANYING THE COLD AIR.
AN UPPER LEVEL LOW PRESSURE SYSTEM OVER THE MIDWEST WILL TRACK
EAST ACROSS PENNSYLVANIA BY MONDAY...AND ANOTHER BY EARLY TUESDAY...
SPREADING ADDITIONAL FLURRIES AND SNOW SHOWERS ACROSS THE
COMMONWEALTH ALONG WITH SHARPLY COLDER AND WINDY CONDITIONS. HIGH
PRESSURE WILL BUILD OVER THE REGION AT MIDWEEK. HOWEVER...AN EAST
COAST STORM COULD POTENTIALLY THREATEN PENNSYLVANIA TO CLOSE OUT
THIS YEAR OR RING IN THE NEXT.
&&
.NEAR TERM /THROUGH TONIGHT/...
RAINFALL HAS REALLY DIMINISHED THIS AFTERNOON AS THE COASTAL LOW
TRACKS NORTHWARD. ADDITIONAL AMOUNTS OF ONLY .01 OR .02 PER HOUR
ARE BEING OBSERVED ACROSS THE LOWER SUSQ. RIVER VALLEY...BUT SNOW
MELT CONTINUES. EARLIER ISOLATED MINOR FLOODING PROBLEMS DO NOT
APPEAR TO HAVE WORSENED...BUT WE DO EXPECT SOME SIGNIFICANT RISES
ON STREAMS AND CREEKS IN THE AREA...AND SHERMAN CREEK AT
SHERMANSDALE ROSE ABOVE CAUTION STAGE AT 1 PM THIS AFTERNOON AND
WILL CREST BELOW FLOOD STAGE TONIGHT.
STRONG LL JET WORKING ACROSS EASTERN PA WILL CONTINUE TO CREATE
GUSTY WINDS NR THE SFC...ESP DOWNWIND /WEST/ OF THE RIDGETOPS.
BUFKIT DATA SUPPORTS GUSTS ARND 25KTS CONTINUING FOR MUCH OF THE
DAY ACROSS EASTERN PA.
COLDER AIR ARRIVES LATER THIS EVENING AND LATE TONIGHT ACROSS THE
NORTHWEST CHANGING LINGERING DRIZZLE AND LIGHT -SHRA TO -SHSN. NOT
EXPECTING MUCH IN THE WAY OF ACCUMS HOWEVER UNTIL FLOW BECOMES
MORE WESTERLY BY LATE SUNDAY AT THE EARLIEST.
&&
.SHORT TERM /SUNDAY/...
UPPER LOW TRACKS EASTWARD ACROSS CENTRAL PA ON SUNDAY WITH COLD
AIR PUSHING INTO EASTERN PA FINALLY. INCREASING CHC OF SNOW
SHOWERS WILL ACCOMPANY THIS WITH SOME MINOR ACCUMULATIONS EXPECTED
MAINLY OVER NORTHWEST SECTIONS. ENS MEAN QPF INDICATES LGT ACCUMS OF
LESS THAN AN INCH POSSIBLE BY SUN AFTN OVR THE NW MTNS AND LAUREL
HIGHLANDS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
UPPER LOW WILL LIFT NORTHEAST ACROSS THE E GRT LKS SUNDAY NIGHT.
LG SCALE FORCING AHEAD OF THIS FEATURE WILL LIKELY SUPPORT A
PERIOD OF SNOW OVR THE ALLEGHENY MTNS SUNDAY NIGHT...WITH SHSN
POTENTIALLY EVEN SURVIVING DOWNWIND OF THE MTNS INTO THE SUSQ
VALLEY.
BRISK/WINDY CONDS AND LES SHWRS WILL ACCOMPANY A REINFORCING SURGE
OF COLDER AIR MON NGT/TUE. HIGH PRES SHOULD BRING SOME IMPROVEMENT
BY THE MIDDLE OF NEXT WEEK. THIS 36-48 HOUR PERIOD WILL LIKELY
CONTAIN SEVERAL INCHES OF SNOW ACROSS THE SNOW BELT OF NW PA.
THE MOST TRANQUIL /THOUGH STILL COLD/ PERIOD NEXT WEEK WILL BE
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS A LARGE AREA OF HIGH
PRESSURE BUILDS ENE FROM THE OHIO VALLEY.
STRONG NEG AO/NAO...+ PNA AND A SRN STREAM EL NINO CONNECTION
WL CONT TO OFFER A SET UP FAVORABLE FOR EAST COAST WINTER STORMS.
12Z GEFS...AND THE OPERATIONAL 06Z EC/ 12Z GFS STILL SHOW A
DEVELOPING AREA OF LOW PRESSURE MOVING NNE - SEVERAL HUNDRED KM
OFF THE SE AND MID ATLANTIC COAST TOWARD THE START OF THE NEXT
DECADE...STAY TUNED. FOR NOW...WILL BROAD-BRUSH A 30-40 PERCENT
CHC FOR SNOW NEW YEARS EVE INTO THE FIRST DAY OF 2010. 12Z
ECMWF...HAS SHOWN A TYPICAL WWD JOG TO THE PATH OF THE LOW - NOW
CLOSER TO THE MID ATLANTIC COAST...WITH A BETTER CHC FOR SNOW
ACROSS OUR CENTRAL AND ERN ZONES LATE NEW YEARS DAY INTO JAN 2ND.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
SFC LOW OVR SE VIRGINIA AT 19Z...WL TRACK ACROSS EASTERN PA/SRN NJ
LATER TONIGHT BRINGING AN END TO THE PERSIST LIGHT RAIN SHOWERS
AND DRIZZLE ACROSS SOUTHEAST PA. ARRIVAL OF OCCLUDED FRONT WILL
BRING AN END TO THE RAIN WITH A BRIEF CHANGOVER TO SNOW POSSIBLE
IN THE NW MTNS BEFORE ENDING THIS EVENING AS CONDITIONS IMPROVE
THIS EVENING. STRONG LL JET WORKING ACROSS EASTERN PA WILL
CONTINUE TO CREATE GUSTY WINDS NR THE SFC THIS AFTN...ESP
DOWNWIND /WEST/ OF THE RIDGETOPS.
LARGE UPPER LOW WILL TRACK EASTWARD ACROSS THE REGION ON SUNDAY...
BRINGING SCATTERED FLURRIES AND SNOW SHOWERS AND WIDESPREAD MVFR
CONDS CENTRAL AND MVFR TO IFR CONDS IN THE WEST.
OUTLOOK...
MON-TUE...NW FLOW. MVFR/IFR WEST WITH FREQ SNOW SHOWERS. CNTRL/EAST
VFR/MVFR WITH SCATTERED SNOW SHOWERS.
WED-THU...VFR.
&&
.HYDROLOGY...
RIVER LVLS CONTINUE TO RESPOND TO THE RAIN AND SNOWMELT...WITH
LATEST MARFC GUIDANCE CONT TO INDICATE MODEST RISES TO OCCUR OVER
SOUTHEAST PA. ADDITIONAL QPF FROM AREAS LIGHT RAIN AND DRIZZLE
WILL BE NEGLIGABLE...WHICH SHUD HELP TO SLOW DOWN ANY MINOR
FLOODING ISSUES TONIGHT. SHERMANSDALE AT SHERMAN CREEK IS ABOVE
CAUTION STAGE AND WILL DROP BELOW BY LATE TONIGHT AS A RESULT.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DEVOIR
NEAR TERM...DEVOIR
SHORT TERM...DEVOIR
LONG TERM...FITZGERALD/LAMBERT
AVIATION...DEVOIR/RXR
HYDROLOGY...DEVOIR
