-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 160315
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1115 PM EDT WED MAY 15 2013

.SYNOPSIS...
A DIFFUSE FRONTAL BOUNDARY WILL SETTLE ALONG OR SOUTH OF THE MASON
DIXON LINE OVERNIGHT. ISOLATED SHOWERS AND THUNDERSTORMS WILL
MEANDER ACROSS THE SOUTHERN THIRD OF CENTRAL PA THROUGH THE EARLY
MORNING HOURS BEFORE DRIER AIR ARRIVES FROM THE NORTH. THE FRONTAL
BOUNDARY WILL BECOME NEARLY STATIONARY OVER THE CENTRAL
APPALACHIANS THROUGH THIS WEEKEND BEFORE RETURNING BACK TO THE
NORTH AS A WARM FRONT EARLY NEXT WEEK. ANOTHER COLD FRONT SHOULD
CROSS THE REGION AROUND THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
850 MB THETA-E RIDGE IS SLOWLY BEING SUPPRESSED SOUTHWARD LATE
TONIGHT. NAM12 SHOWS THE RICHEST PLUME OF MOISTURE EXTENDING FROM
SOUTHEAST OHIO THROUGH SOMERSET...BEDFORD FULTON AND FRANKLIN
COUNTIES FOR THE NEXT SEVERAL HOURS BEFORE FINALLY BEING
SUPPRESSED SOUTH OF THE MARYLAND BORDER BY 10Z. AN UPSTREAM
SHORTWAVE EMBEDDED IN THE FAST FLOW ALOFT SHOULD KEEP ISOLATED
SHOWERS AND STORMS GOING THROUGH THE PRE DAWN HOURS...SO EXTENDED
POPS OVER THE SOUTHERN THIRD OF CENTRAL PA UNTIL THAT TIME.

OVERNIGHT MINS SHOULD RANGE FROM AROUND 60F ACROSS THE SOUTH TO
THE MID TO UPPER 40S ACROSS THE NORTHERN TIER.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
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 /THURSDAY 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 /03Z THURSDAY THROUGH MONDAY/...

-- Changed Discussion --
AT 03Z THE WEAK COLD FRONT IS STILL VERY CLOSE TO I-80. MESO ANAL
SHOWS THE SOUTHERN HALF OF THE STATE IS STILL MARGINALLY UNSTABLE
AND RADAR CONTINUES TO SHOW VERY SMALL SHOWERS AND THUNDERSTORMS
RACING SE IN THE FAST WNW FLOW ALOFT. JST/AOO ARE THE CLOSEST TO
THE POP-UP CONVECTION...BUT EXPECTATIONS ARE THAT THE PRECIP WILL
STAY SOUTH OF OUR TERMINALS LEAVING MAINLY VFR CONDITIONS FOR THE
REMAINDER OF THE OVERNIGHT. THERE COULD BE SOME LATE NIGHT FOG
WHERE IT RAINED EARLIER TODAY...BUT CONFIDENCE IS LOW ON THIS.

THE FRONT WILL STALL JUST SOUTH OF THE PA BORDER THURSDAY...SO THE
PA TERMINALS WILL BE VFR AFTER ANY FOG ISSUES BURN OFF EARLY IN
THE DAY.


.OUTLOOK...

FRI...NO SIG WX EXPECTED.

SAT-SUN...AREAS OF REDUCED CONDITIONS WITH SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS.

MON...REDUCED CONDITIONS WITH RAIN POSSIBLE.
-- End Changed Discussion --

&&

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

&&

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