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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 160542
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
142 AM EDT THU MAY 16 2013

.SYNOPSIS...
A DIFFUSE FRONTAL BOUNDARY ALONG THE MASON DIXON LINE EARLY THIS
MORNING WILL SLOWLY SINK SOUTHWARD INTO THE VIRGINIAS THROUGH THE
DAY. HIGH PRESSURE SHOULD BRING MAINLY DRY CONDITIONS FROM FRIDAY
INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
ISSUED EARLY UPDATE TO REFINE/INCREASE POPS ALONG THE SRN TIER
ZONES. UPSTREAM CONVECTION MOVG ESEWD ACRS CNTRL OH...ASSOCD WITH
COMPACT SHORTWAVE TRACKING ALONG LLVL MSTR/CONVERGENCE AXIS...LOOKS
POISED TO REACH THE LAURELS/S-CNTRL MTS BY DAYBREAK. THE HI-RES
MESO GUIDANCE ALSO SHOWS THIS PLAYING OUT OVER THE NEXT SEVERAL
HOURS.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/...
W-E ORIENTED Q-STNRY FRONTAL BOUNDARY SHOULD LINGER JUST SOUTH OF
THE PA/MD BORDER EARLY THURS AM BEFORE SLOWLY SINKING SWD INTO
WV/VA. KEPT SOME SCHC TO LOW CHC POPS ALONG/SOUTH OF THE PA
TURNPIKE FOR DAY 2 WITH ANY AFTN CONVECTION REMAINING ISOLD TO SCT
AT BEST. OR TO PUT IT ANOTHER WAY...MOST OF THE CWA SHOULD BE DRY.

A WEAK SECONDARY/BACKDOOR COLD FRONT SHOULD PUSH SWD ACRS CNTRL PA
LATER THURS...BEFORE SFC RIDGING TAKES HOLD OVER THE AREA TOMORROW
NGT INTO DAY 3. DAYTIME MAXES SHOULD RANGE BTWN 70-80F WITH SOME
LOCATIONS OVER THE ERN VALLEYS CLIMBING INTO THE LOW 80S. LOWS
WILL VARY FROM AROUND 40F IN THE NORTH TO THE LOW 50S ALONG THE
SRN TIER ZONES.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
FORECAST CONTINUES TO LEAN TOWARD A DRIER SOLUTION THU NIGHT
THROUGH SAT AS DRIER AIR EDGES IN FROM THE N/NW...HELPING TO NUDGE
FRONTAL BOUNDARY SOUTH OF PA. LOWS WILL DIP BACK INTO THE 40S
NORTH/50S SOUTH WITH DAYTIME HIGHS IN THE UPPER 60S TO MID 70S.

RIDGE CONTINUES TO BUILD IN OVERHEAD THROUGH THE WEEKEND...BUT
RETURN FLOW BEGINS AROUND SURFACE HIGH BY LATE WEEKEND WHICH WILL
PUSH A WARM FRONT BACK IN OUR DIRECTION. COULD SEE A SCT
SHOWER/TSTM ON SUNDAY...WITH BEST CHANCE IN THE SW.

BY EARLY NEXT WEEK UPPER-LEVEL TROUGH OVER ERN CANADA SHIFTS EWD
INTO THE NRN ATLC AND TROUGHING DEVELOPS OVER THE INTER MTN
WEST/HIGH PLAINS STATES. THE MODELS IN GENERAL AGREE ON THIS
PATTERN EVOLUTION. AT THE SFC...RETURN FLOW/INC LLVL MSTR BRINGS
INCREASING CHANCES OF AFTN SHOWERS/TSTMS MON-TUE. THE GFS IS MORE
AGGRESSIVE THAN THE EC WITH THE CONVECTION. WHILE THE ECMWF-BASED
GUIDANCE IS DRIER OVERALL IT IS A FEW TO SEVERAL DEGREES LOWER
WITH MAXES THAN THE GFS-BASED GUIDANCE...PERHAPS OWING MORE TO
COOLER EASTERLY LLVL FLOW WITH SOME INTERACTION WITH RETURNING
Q-STNRY BOUNDARY FROM THE SOUTH. THE AREA SHOULD BREAK INTO THE
WARM SECTOR BY TUESDAY ALLOWING TEMPS TO SURGE ABOVE NORMAL.

THE MID-TO-HIGH LATITUDE FLOW BECOMES INCREASINGLY BLOCKY BY LATE
IN THE PERIOD...WITH BROAD OPERATIONAL AND ENSEMBLE AGREEMENT ON A
TROUGH/RIDGE/TROUGH CONFIGURATION FROM THE PAC NW/PLAINS/NORTHEAST.
WHILE THE DETAILS ARE UNCERTAIN...THE GENERAL TREND IS TOWARD
SLOWING EASTWARD PROGRESSION OF THE TROUGH...THUS INCREASING POPS
FOR MID/LATE WEEK WITH POTENTIAL FOR SLOWER EVOLUTION OF SYNOPTIC
SYSTEMS IN HIGHLY AMPLIFIED LG SCALE PATTERN.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
A STALLED FRONTAL BOUNDARY LYING ACROSS SOUTHERN PA WILL PROVIDE
THE FOCUS FOR A FEW SHRA AND EVEN AN ISOLATED TSRA THIS MORNING.
05Z DWPT DEPRESSIONS AND NR TERM MDL DATA SUGGEST MDT AND LNS
WILL LIKELY SEE A BIT OF FOG IN THE 08Z-12Z TIME FRAME. MDL
GUIDANCE SUGGESTS VSBYS WILL GO NO LOWER THAN MVFR. HOWEVER...WOULD
NOT RULE OUT A BRIEF DIP TO IFR AT MDT/LNS...WHERE GROUND REMAINS
WET FROM YESTERDAY/S RAINFALL.

HIGHER DWPT DEPRESSIONS AT JST AND AOO INDICATE THEY WILL LIKELY
REMAIN VFR UNLESS A HEAVY SHRA/TSRA HAPPENS TO OCCUR BEFORE DAWN.

ANY EARLY FOG SHOULD LIFT SHORTLY AFTER SUNRISE. HOWEVER...WILL
STILL HAVE TO CONTEND WITH THE SLIGHT CHC OF A LATE AM SHRA/TSRA
ACROSS THE SOUTHERN AIRFIELDS. BY AFTN...THE FRONTAL BOUNDARY
SHOULD SHIFT SOUTH OF PA...RESULTING IN A HIGH DEGREE OF
CONFIDENCE IN VFR CONDS ACROSS THE ENTIRE STATE.

.OUTLOOK...

FRI-SUN...NO SIG WX EXPECTED.
MON...AM LOW CIGS POSSIBLE.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...GARTNER/STEINBUGL
LONG TERM...RXR
AVIATION...FITZGERALD