-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 180813
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
413 AM EDT TUE JUN 18 2013

.SYNOPSIS...
AN UPPER LEVEL DISTURBANCE WILL CREATE PERIODIC SHOWERS AND
THUNDERSTORMS ALONG A STALLED FRONTAL BOUNDARY THROUGH TUESDAY
NIGHT. HIGH PRESSURE WILL KEEP CONDITIONS DRY AND NEAR AVERAGE
TEMPERATURES FOR THE REST OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
BROAD UPPER LEVEL SHORTWAVE TROUGH WILL MOVE EASTWARD WHILE AT
THE SURFACE...WEAK COLD FRONT CURRENTLY PLACED ALONG LAKE ERIE
WILL PROGRESS SOUTHWARD. INITIALLY...THE SITUATION WILL HELP
ENHANCE SHOWERS AND POSSIBLE THUNDERSTORMS THROUGH EARLY TUESDAY.
ANOTHER SHORTWAVE MOVING ACROSS THE MID-ATLANTIC WILL MOVE
EAST/NORTHEAST AND LOW LEVEL CONVERGENCE BETWEEN THE SURFACE LOW AND
SOUTHWARD COLD FRONT SHOULD ENHANCE SHOWERS AND THUNDERSTORMS IN
THE AFTERNOON...MAINLY SOUTH OF PIT.

SKY COVERAGE WILL BE MOSTLY CLOUDY. HENCE...LIMITED INSTABILITY
WILL PERSIST THROUGH THE AFTERNOON. HOWEVER...MODEST MID-LEVEL
FLOW WILL ENHANCE CONVECTION...YIELDING AT LEAST LOW PROBABILITIES
OF SEVERE THUNDERSTORMS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
MODELS IN FAIR AGREEMENT WITH TIMING OF FRONT TO MOVE SOUTH OF THE
FORECAST AREA BY TONIGHT. HIGH PRESSURE WILL SETTLE OVER THE REGION AND
KEEP TEMPERATURES COOLER THAN NORMAL WEDNESDAY AND THURSDAY.
WARMER THAN AVERAGE TEMPERATURES WILL FOLLOW ON FRIDAY AS WARM AIR
ADVECTION FROM THE SOUTHWEST BEGINS TO PERSIST.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
-- Changed Discussion --
WARM AND HUMID CONDITIONS ARE FORECAST INTO EARLY NXT WEEK AS BROAD
RIDGE IS STILL PROJECTED TO BLD OVR THE SRN AND ERN CONUS.  HAVE
USED THE WARMER MOS GUIDANCE ONCE AGAIN FOR THE PD GIVEN CONSISTENT
HT PROGS AS DEPICTED BY GFS AND ECMWF MDLS OVR THE PAST CPL OF DAYS.

CHC/NR CLIMO POPS WERE ALSO INCLUDED THROUGH THE WEEKEND GIVEN THE
INSTABILITY THAT WL ACCOMPANY THE WARMTH AND MSTR...WITH LIMITATIONS
IMPOSED BY MID LVL CAPPING AND DEPENDENCY ON SHRTWV SPPRT ACRS THE
NRN PERIPHERY OF THE RIDGE.
-- End Changed Discussion --

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
GENL VFR IS ANTICIPATED THIS MRNG...BUT SVRL FEATURES MAY MAR THE
FORECAST WITH POTENTIAL RESTRICTIONS.  PATCHY MVFR FOG IS POSSIBLE
THRU THE PERIDAWN HRS GIVEN THE MOIST BNDRY LYR...BUT HIGH
MDL-PROGGED CONDENSATION PRES DEFICITS...DRY ADVCTN IMMEDIATELY
ABOVE THE SFC LYR...AND INCRSD MID LVL CLDINESS ARE EXPECTED TO
PRECLUDE WIDESPREAD IFR...OR MVFR RESTRICTIONS.

OTHERWISE...SCT SHWRS ARE EXPECTED TO DVLP...AND BECOME MORE
WIDESPREAD BY THIS AFTN AS A CDFNT SAGS ACRS THE UPR OH VALLEY
REGION.  THE BTR CHC FOR TERMINAL EFFECTS WL BE FOR PORTS S OF PIT
AS HEATING/DESTABILIZATION MAY SPPRT MORE WIDESPREAD SHWR AND TSTM
DVLPMNT IN CONJUNCTION WITH FRONTAL PROGRESS.

OUTLOOK.../TONIGHT THROUGH SATURDAY/...
RESTRNS ARE PSBL S OF PIT TNGT AS THE CDFNT EXITS...BUT BLDG HIGH
PRES IS EXPD TO PRODUCE GENL VFR FOR THE RMNDR OF THE WEEK.
-- End Changed Discussion --

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$