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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 170315
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1115 PM EDT THU MAY 16 2013

.SYNOPSIS...
A FRONTAL BOUNDARY WILL REMAIN ALONG THE MASON DIXON LINE INTO
FRIDAY MORNING. MEANWHILE...HIGH PRESSURE WILL MIGRATE EASTWARD
ACROSS SOUTHEASTERN CANADA WITH ONSHORE FLOW DEVELOPING ACROSS THE
MID- ATLANTIC 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 AM FRIDAY MORNING/...
A LOVELY EVENING OUT THERE...HIGH PRESSURE WITH MOSTLY CLEAR SKIES
AND LIGHT WINDS TO PREVAIL ACROSS CENTRAL PA OVERNIGHT. THE DRIEST
AIR...AS DEPICTED BY GEFS NEGATIVE PWAT ANOMALIES...REMAIN ACROSS
THE NORTHERN HALF OF THE STATE...WHERE READINGS ARE LIKELY TO DIP
INTO THE U30S. CAN/T RULE OUT SOME PATCHY FROST UP THERE...BUT
GROWING SEASON HAS NOT OFFICIALLY BEGUN UP THERE...SO NO ADVISORY
NEEDED.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
SFC HIGH PRES WILL SLIDE EWD FROM ONTARIO TO THE MARITIMES BY 12Z
SUNDAY...WITH ONSHORE FLOW DEVELOPING ACRS THE MID-ATLC STATES.
EXPECT SFC RIDGING AND LACK OF ANY SIGNIFICANT MID-UPPER LEVEL
FORCING TO LIMIT PCPN THROUGH MOST OF THE PERIOD. THE HIGHEST POPS
ARE OVER THE SERN ZONES SAT NGT AS AN UPPER LEVEL WAVE DRIFTS EWD
ACRS KY/TN INTO THE CNTRL APPLCHNS AND INTERACTS WITH ONSHORE MSTR
FEED INTERSECTING RETREATING Q-STNRY/WARM FRONT LIFTING NWD OVER
THE MID-ATLC. EXPECT LOW CLOUDS TO DEVELOP FROM SOUTH TO NORTH ON
SAT NGT IN SERLY FLOW REGIME. TEMPS WILL BE WARMER ON FRIDAY WITH
MORE SUN.

&&

.LONG TERM /FRIDAY 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 FRI
NIGHT THROUGH SUNDAY...WITH LOW LEVEL FLOW TURNING S/SE BRINGING
INCREASE IN CLOUDS AND TAPPING ONSHORE COMPONENT RESULTING IN
COOLER HIGHS FOR SAT/SUN. WEAKENING REMNANTS OF UPPER LOW EXITING
TEXAS WILL DRIFT TOWARD WV OVER THE WEEKEND...AND MAY HELP TO
ENHANCE PRECIP OVER MID-ATLANTIC REGION. MODELS STILL TRYING TO
GENERATE SOME PRECIP MAINLY SAT NIGHT-SUN...SO KEPT POPS INTACT
AND CONTINUED TYPE AS STRATIFORM DURING THAT PERIOD AS EXPECTING
MAINLY STABLE CONDITIONS EAST OF ALLEGHENY FRONT /INSTABILITY WILL
REMAIN TO THE WEST BEHIND AN APPROACHING WARM FRONT/.

WARM FRONT DOES 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 /03Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
AM A LITTLE CONCERNED ABOUT SOME LOW CLOUDS CREEPING UP INTO
JOHNSTOWN ON A SLIGHTLY MOISTER WSW FLOW...OTHERWISE WIDESPREAD
VFR CONDS EXPECTED THROUGH THE FORECAST PERIOD AS WEAK HIGH
PRESSURE BUILDS OUT OF THE GREAT LAKES.

.OUTLOOK...

FRI...NO SIG WX EXPECTED.

SAT...CONDITIONS LOWERING OVER SOUTHERN AREAS IN THE AFTERNOON
WITH RAIN/DRIZZLE.

SUN-MON...REDUCED CONDITIONS WITH RAIN/DRIZZLE.

TUE...MVFR WITH SHOWERS/THUNDERSTORMS.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...GARTNER/STEINBUGL
NEAR TERM...DEVOIR/GARTNER
SHORT TERM...GARTNER/STEINBUGL
LONG TERM...RXR
AVIATION...LA CORTE