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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 171855
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
255 PM EDT FRI MAY 17 2013

.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN STALLED ALONG THE MASON DIXON LINE
TODAY AS HIGH PRESSURE MIGRATES EASTWARD ACROSS SOUTHEASTERN
CANADA. ONSHORE FLOW WILL DEVELOP ACROSS THE MID- ATLANTIC
REGION OVER THE WEEKEND ALONG THE SOUTH SIDE OF THE
HIGH...BRINGING CLOUDS AND INCREASING CHANCE OF SHOWERS TO PARTS
OF THE REGION. THE FRONTAL BOUNDARY WILL SLOWLY PUSH BACK TO THE NORTH
AS A WARM FRONT OVER THE WEEKEND...AND LIFT NORTH OF THE AREA BY
EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
LATEST VIS IMAGERY AND SFC OBS SHOW MOSTLY SUNNY SKIES ACROSS
CENTRAL PA THIS FRI AND EXPECT THAT TO CARRY THROUGH THE LATE AFTERNOON
HOURS AS SFC HIGH PRS BUILDS ACROSS THE REGION.

RADAR REMAINS CLEAR OF RETURNS OVER PA...BUT REGIONAL RADAR
IMAGERY SHOWS SHOWERS POPPING UP ALONG THE HIER ELEVATION IN WV
AS MOISTURE SURGES NWD ON INCREASING SERLY FLOW. THUS CAN`T RULE
A STRAY SHRA/TSRA THIS EVENING...SO WILL KEEP SLIGHT/LOW CHC
POPS OVER THE LAURELS.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
JUST A SLIGHT CHC OF A SHOWER WILL LAST INTO THE NIGHT OVER SRN
BORDER. THE DEGREE OF INFLUENCE THE FILLING UPPER LOW COMING OUT
OF THE PLAINS WILL HAVE IS A TOUGH CALL. HOWEVER...GENERAL MDL
PREFERENCE IS TO KEEP THE BULK OF THE SHRA S OF THE STATE. CERTAINLY
THE HIGH CLOUDS WILL THICKEN UP AND COULD HELP KEEP TEMPS MILDER
TONIGHT THAN THIS MORNING...WITH MINS IN THE N IN THE M/U40S AND
M50S S. EXPECT LITTLE/NO WIND TONIGHT OVER MOST OF THE
AREA...EXCEPT FOR THE WRN MTS FARTHER FROM THE AXIS OF THE
WEAKENING SFC RIDGE. THE GENERAL FLOW PATTERN DOES BECOME MORE
E/SERLY LATER TONIGHT AND CERTAINLY DURING THE DAY ON SAT. THE
MID/HIGH CLOUDS COULD KEEP MAXES DOWN IN THE L70S FOR MOST AREAS.
HOWEVER...HEATING SHOULD BE SUFFICIENT TO POP A FEW CU AGAIN ON
SAT...ESP OVER THE HIGHER ELEVATIONS. THE MOISTURE FROM THE
ATLANTIC OCEAN WILL START TO BE DRAWN NORTHWARD ALONG THE
APPALACHIANS AND WILL START TO BUILD UP LATER SAT NIGHT. THIS
SHOULD KEEP MINS MILD. WILL ALSO KEEP THE LOW CHC FOR SOME LIGHT
RAIN AS THE MARITIME MSTR CLIMBS UPHILL SAT NIGHT...WITH HIGHER
30-40 POPS S AND SLIGHT CHC N.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
NO BIG CHANGES NECESSARY TO LONGER RANGE FORECAST BASED ON LATEST
COMPUTER GUIDANCE.

NEARLY STATIONARY FRONTAL BOUNDARY WILL REMAIN SOUTH OF PA THROUGH
SUNDAY. LIGHT UPSLOPE FLOW CONTINUES AND SHOULD MAKE SUN AS COOL
OR COOLER THAN SAT.

WARM FRONT APPEARS TO PUSH THROUGH ON MONDAY...WITH MENTION OF
SCT SHOWERS/TSTMS. PWATS INCREASE MORE NOTICEABLY HEADING INTO
TUE-WED AS LARGE SCALE PATTERN AMPLIFIES...AND HEIGHTS BUILD OVER
PA. MAIN SYNOPTIC FEATURE OF INTEREST WILL BE AN UPPER LOW OVER
THE NRN PLAINS/UPR MS VLY. H5 HGTS SHOULD RISE DOWNSTREAM OF THIS
SYSTEM...WITH CENTRAL PA SOLIDLY IN THE WARM SECTOR BY TUE. THIS
SHOULD AFFORD ONE OR TWO VERY WARM LATE SPRING DAYS WITH HIGHS
75-80F AND LOW CHANCES FOR DAILY TSTMS. THERE IS NOTICEABLE SPREAD
BETWEEN THE GFS/ECMWF CONCERNING THE POTENTIAL EVOLUTION OF THE
UPPER MIDWEST CUT-OFF...BUT SETTLED ON BRINGING THE COLD FRONT
THROUGH ON WED-WED NIGHT /ALONG WITH HIGHEST POPS/. STRONG SURFACE
HIGH BUILDS ACROSS GLAKES UNDER UPPER TROUGH LATE WEEK...BRINGING
COOLER AND DRIER CONDITIONS TO CENTRAL PA.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
EXPECT A CONTINUATION OF VFR CONDS WITH PATCHES OF SCT-BKN CIRRUS
AS WEAK HIGH PRESSURE BUILDS OVER THE REGION.

MVFR CIGS COULD DEVELOP AS EARLY AS LATE TONIGHT INVOF JST/AOO AS
LLVL FLOW SHIFTS TO THE ESE. CONFIDENCE IN MVFR CIGS IS LOW
TONIGHT. HOWEVER THE DEVELOPING ONSHORE/SELY FLOW WILL EVENTUALLY
INTERSECT A RETURNING WARM FRONT AND RESULT IN HIGHER CONFIDENCE
FOR CIG/VIS RESTRICTIONS AND PSBL LGT RAIN/DRIZZLE/FOG LATER SAT
INTO MONDAY. WARM FRONT WILL LIFT NORTH OF PA ON TUESDAY WITH
SUMMERTIME WARM/MOIST CONDITIONS LKLY FUELING DIURNAL ISOLD-SCT
SHWRS/TSTMS.

.OUTLOOK...

SAT...CIGS LOWERING WITH MVFR/IFR LKLY BY SAT NGT.
SUN-MON...MVFR/IFR CIGS WITH OCNL -RA/-DZ.
TUE...VFR/MVFR WITH SCT SHOWERS/TSTMS.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...GARTNER
NEAR TERM...GARTNER/DANGELO
SHORT TERM...DANGELO/GARTNER
LONG TERM...DANGELO/RXR
AVIATION...GARTNER