-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 201257
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
857 AM EDT MON MAY 20 2013

.SYNOPSIS...
THE RISK FOR AFTERNOON AND EVENING SHOWERS AND STORMS WILL
CONTINUE THROUGH TUESDAY. A BETTER CHANCE FOR WIDESPREAD
ACTIVITY ON WEDNESDAY...AS AN UPPER LEVEL DISTURBANCE MOVES
THROUGH.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
A RELATIVELY WEAK FLOW REGIME REMAINS ENTRENCHED OVER THE FORECAST
AREA TODAY...WITH ONE WEAK SYSTEM ATTEMPTING TO MOVE DIRECTLY INTO
THE RIDGE AXIS ALONG THE EAST COAST TO OUR SOUTH AND THE MAIN
LARGE SCALE PLAYER STILL BACK OVER THE DAKOTAS TODAY. WHILE
SOUTHERLY FLOW HAS ALLOWED LOW LEVEL MOISTURE TO CREEP STEADILY
INTO THE AREA...RESULTING IN DEWPOINTS IN THE 60S THIS MORNING AND
POSSIBLY LOCALLY TOUCHING 70F IN OHIO THIS AFTERNOON...THERE IS
SEEMINGLY LITTLE TO HELP INITIATE MUCH IN THE WAY OF CONVECTION.
LARGE SCALE LIFT IS WELL OFF TO THE WEST...WITH THE MODELS REALLY
ONLY HINTING AT MUCH IN THE WAY OF DAYTIME DIURNAL CONVECTION
ALONG THE SOUTHERN AND EASTERN PORTIONS OF THE AREA. GIVEN THE
MOISTURE AND INSTABILITY PROFILE...ISOLATED SHOWERS/THUNDERSTORMS
SEEM POSSIBLE IN THESE LOCATIONS...HOWEVER ANYTHING ORGANIZED
SEEMS HIGHLY UNLIKELY.

DUE TO OUR POSITION RELATIVE TO THE LARGE SCALE FEATURES...MIXING
SEEMS LIKE IT SHOULD BE MOST EFFICIENT OVER THE NORTHWESTERN
PORTIONS OF THE FORECAST AREA. THIS IS CO-LOCATED WITH THE AREA OF
BEST WARM ADVECTION AT 850 MB...SO FROM ZANESVILLE TO MERCER
TEMPERATURES WERE INCREASED THIS AFTERNOON. ELSEWHERE...THE STATUS
QUO REMAINS WITH HIGHS IN THE LOWER TO MIDDLE 80S WIDESPREAD THIS
AFTERNOON. FRIES
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
ANY CONVECTION THAT DEVELOPS TODAY WILL AGAIN DISSIPATE WITH THE
LOSS OF DAYTIME HEATING.

RIDGE WILL REMAIN IN PLACE THROUGH TUESDAY. MODELS CONTINUE TO
PROMOTE WIDESPREAD ACTIVITY LATE TONIGHT AND AGAIN TUE AFTERNOON.
THIS SEEMS TO BE OVERDONE AS THERE IS NO FORCING COMPONENT OR
UPPER LEVEL WAVE TO GET THINGS ROLLING. THINK THE BEST WAY TO
HANDLE THE SITUATION IS TO CONTINUE WITH CHANCE POPS.

EXPECT A BETTER CHANCE FOR SHOWERS AND STORMS WED AS THE RIDGE
BREAKS DOWN AS A RESULT OF LARGE SHORTWAVE TROUGH DIGGING INTO THE
UPPER MIDWEST. MORE SUBSTANTIAL WAVES WILL ROTATE AROUND THIS
FEATURE AND INTO THE UPPER OHIO VALLEY BY WED AFTERNOON.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE DISTRICT REMAINS IN THE WARM SECTOR FOR TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. TEMPERATURES WILL REMAIN ABOVE NORMAL ALONG WITH
A CHANCE OF DIURNAL SHOWERS AND THUNDERSTORMS. A COLD FRONT
MOVING SLOWLY SOUTH FROM THE GREAT LAKES THURSDAY WILL BRING
LIKELY SHOWERS AND THUNDERSTORMS FOR LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT. BEHIND THE COLD FRONT FRIDAY THE RISK OF SHOWERS
WILL DIMINISH AND TEMPERATURES WILL DROP BELOW NORMAL. DRY WEATHER
CAN BE EXPECTED FOR FRIDAY NIGHT INTO SUNDAY WITH TEMPERATURES
FALLING INTO THE 40S FOR OVERNIGHT LOWS SATURDAY MORNING.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
SPOTTY SHOWERS OVER THE EVENING SEEM TO HAVE DISSIPATED...SO
EXPECT THAT THE REST OF THE NIGHT WILL REMAIN DRY. IFR STRATUS IS
EXPECTED TO CONTINUE OVERNIGHT AT DUJ...ALTHOUGH THERE IS SOME
UNCERTAINTY AS TO WHETHER THE STRATUS WILL MANAGE TO PUSH ANY
FARTHER TO THE WEST. HAVE CONTINUED SCT IFR CIGS NEAR DAWN TO
ACCOUNT FOR THIS UNCERTAINTY. CONDITIONS SHOULD RETURN TO VFR AT
ALL LOCATIONS ACROSS THE REGION BY LATE MORNING. AN EXITING UPR
LVL WAVE MAY BRING A SHWR/TSTM E OF PIT BUT CONFIDENCE TOO LOW FOR
MENTION IN TAFS ATTM. ANOTHER ROUND OF MVFR FOG IS POSSIBLE LATE
MONDAY NIGHT INTO TUESDAY MORNING...AND HAVE ADDED THIS IN THE 30
HOUR TAF FOR PIT.

.OUTLOOK.../TUESDAY THROUGH FRIDAY/...
CHC FOR SHWR/TSTMS WL RETURN TUE AFTN AND INCR THRU THU EVE AS A
CDFNT APRCHS AND MOVES THRU. BLDG HIGH PRES AND VFR CONDS EXPD
FRI.

&&

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

&&

$$