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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 151244
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
844 AM EDT WED MAY 15 2013

.SYNOPSIS...
A COLD FRONT WILL CROSS THE AREA THIS AFTERNOON...BRINGING THE
RISK FOR SHOWERS AND STORMS. DRY WEATHER WILL RETURN FOR MOST OF
THE AREA ON THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
HIGHER WINDS STARTING TO MIX DOWN TO SURFACE. THE MAIN CONCERN
WILL BE HOW MUCH SUNSHINE WE WILL GET TODAY.
REMAINDER UNCHANGED...

AT THIS TIME...STILL HAVE LOW CONFIDENCE CONCERNING HOW MUCH
CONVECTION WILL DEVELOP. FRONT IS SLATED TO CROSS THE AREA THIS
AFTERNOON...BUT THE LACK OF STRONG FORCING AND THE PRESENCE OF A
CAP IN THE FORECAST SOUNDINGS WILL BE LIMITING FACTORS FOR TODAY.

THE PRIMARY CONCERN IS THE POTENTIAL FOR SCATTERED STRONG
THUNDERSTORM DEVELOPMENT THIS AFTN. STRONG WARM ADVCTN ABOVE THE
BNDRY LYR IS FORECAST TO MIX OUT TO TEMPS ARND 80F OVR AREAS SOUTH
OF I 80...RESULTING IN STEEP LAPSE RATES IN A HIGH SHEAR
ENVIRONMENT. HOWEVER...THIS MAY NOT BE WARM ENOUGH...AS LATEST
FORECAST SOUNDINGS ARE SHOWING CONVECTIVE TEMPS IN THE LOW 90S
EARLY THIS AFTERNOON...FALLING TO THE LOW 80S BY LATE AFTERNOON.
THE COVERAGE OF SHOWERS AND STORMS SHOULD EXPAND LATE THIS
AFTERNOON AS A MID LVL THERMAL TROF WITH THE NXT CROSSING
SHORTWAVE RAPIDLY ERODES THE CAP.

WITH THE WIND FIELD PROGNOSIS...EXPECTED LAPSE RATES...AND A
MUCAPE OF 1000 TO 2000 J/KG...WILL CONTINUE THE MENTION OF A
SLIGHT SEVERE RISK IN THE HAZARDOUS WEATHER OUTLOOK...PRIMARY
THREAT COMING FROM DAMAGING WIND. THIS WILL NEED TO BE CLOSELY
MONITORED THROUGHOUT THE DAY.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
FRONT WILL SLOWLY PUSH SOUTH INTO WEST VIRGINIA TONIGHT AS AN
UPPER LEVEL TROUGH STRENGTHENS ACROSS NEW ENGLAND. SCATTERED
SHOWERS ARE THUS POSSIBLE...MAINLY FROM I-70 SOUTHWARD...ALBEIT
WITH DIMINISHING CHANCES THROUGH THE PERIOD.

A GOOD PUSH OF COOLER AND DRIER AIR IS INDICATED IN THE WAKE OF
THE FRONT AND HAVE ADJUSTED TEMPERATURES AND DEW POINTS DOWN
CLOSER TO NEW GFS MOS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A SERIES OF SHORTWAVES EMBEDDED IN LOW AMPLITUDE RIDGE OVER THE
EASTERN CONUS WILL MOVE TOWARDS THE OHIO VALLEY THROUGH THE WEEKEND
FOLLOWED BY AN APPROACHING TROUGH BY THE END OF THE PERIOD. MODELS
ARE IN AGREEMENT WITH OVERALL PATTERN BUT DIFFER IN LOCATION AND SET
UP OF BOUNDARY ON THE WEEKEND. KEPT IN NO HIGHER THAN CHANCE POP FOR
THE MAJORITY OF THE PERIOD KEEPING IT IN LINE WITH MEX GUIDANCE.
TEMPERATURES WILL GRADUALLY RISE THROUGH NEXT WEEK.

&&

.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
A WRM FNT WL CONT TO LIFT NWD TNGT...WITH GENL VFR CONDS EXPD
INTO WED. LLVL JET PUSHES INTO OH OVRNGT...SO ADDED LLWS TO THE
ZZV TAF. OTRW EXP SW WNDS TO GUST ARND 25KT WED. A CDFNT WL DROP S
WED AS WELL...WITH SOME SHWRS/TSTMS EXPD TO DVLP ESP IN THE
AFTN...MAINLY S OF I 80. ADDED AFTN VCTS TO ALL SITES EXCEPT FKL
AND DUJ...WHERE LESS INSTAB IS EXPD. AFT FROPA EXP A WSHFT TO THE
W.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
THE CDFNT SHOULD PUSH S OF THE RGN WED NGT WITH GENL VFR CONDS
EXPD THRU FRI. SHWR/TSTM CHCS WL INCR AGAIN FRI NGT THRU SUN AS A
WRMFNT LIFTS SLOWLY N ACRS THE RGN.

&&

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

&&

$$