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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 160619
AFDCTP

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

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

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
ADDITIONAL TWEAKS WERE MADE TO THE NEAR TERM GRIDS TO ACCOUNT FOR
TSTMS MOVG ESEWD FROM E-CNTRL OH INTO SW PA. THIS CONVECTION IS
ASSOCD WITH WITH A COMPACT SHORTWAVE TRACKING EWD FM THE OH VLY
ALONG LLVL MSTR/CONVERGENCE AXIS DRAPED ALONG I-70/PA TURNPIKE.
THE HI-RES MESO GUIDANCE...AND DETERMINISTIC MODELS TO A LESSER
EXTENT...ARE HANDLING THE EVOLUTION OF THE UPSTREAM CONVECTION
REASONABLY WELL - TAKING IT EWD ACRS THE LAUREL/S-CNTRL MTNS
DURING THE PRE-DAWN HOURS AND POSSIBLY INTO THE LWR SUSQ VLY
AROUND DAYBREAK. CONFIDENCE IN THE DETAILS LOWERS AFT 12Z.

THE LLVL BOUNDARY AND CORRESPONDING MSTR CONVERGENCE/PW AXIS WILL
REMAIN THE FOCUS FOR ISOLD SHOWERS/TSTMS THRU THE DAY. CONSENSUS
OF OPERATIONAL MODEL DATA KEEPS THE BULK OF THE CONVECTION ALONG
AND MAINLY SOUTH OF THE PA/MD BORDER THIS AFTN. GIVEN WEAK LOW-
MID LVL FORCING AND THE GUIDANCE HAVING ITS USUAL FITS WITH
CONVECTION...WILL SIMPLY BROAD-BRUSH THE FAR SRN TIER ZONES WITH
LOW POPS THRU THE AFTN/EVE HOURS. THE NRN 2/3RDS OF THE CWA WILL
STAY DRY.

NLY FLOW ASSOCD WITH HIGH PRES MIGRATING EWD ACRS SERN CANADA WILL
PUSH THE MSTR BNDRY SWD INTO THE CNTRL APPLCHNS/SRN MID-ATLC
STATES TONIGHT. CLEARING SKIES ALONG WITH AREA OF BLW NORMAL
PWAT SINKING SWD INTO NRN PA WILL ALLOW MINS TO DROP INTO THE
UPPER 30S TO LOW 40S IN THE NRN MTNS. U40S-M50S WILL BE COMMON
ACRS THE CNTRL AND SRN ZONES.
-- End Changed Discussion --

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
HIGH PRES WILL SLIDE ACRS NRN NEW ENGLAND WITH THE LLVL WINDS
SHIFTING AROUND TO THE EAST-SOUTHEAST BY THE END OF THE PERIOD.
THIS SHOULD ALLOW THE MSTR BNDRY LINGERING OVER THE VIRGINIAS TO
SLOWLY PUSH BACK NWD AS A WARM FRONT. WHILE NO PCPN IS EXPECTED
FOR DAY 2...LOOK FOR SOME INCREASE IN CLOUDS ESPECIALLY TOMORROW
NIGHT IN THE SOUTH. TEMPS WILL AVG NEAR SEASONALLY NORMALS.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY 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 /06Z THURSDAY THROUGH MONDAY/...
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.

&&

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

&&

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