Area Forecast Discussion
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000
FXUS61 KPBZ 202329
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
729 PM EDT SAT SEP 20 2014

.SYNOPSIS...
A COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS ON SUNDAY. HIGH
PRESSURE WILL DOMINATE THE REMAINDER OF THE WEEK WITH DRY WEATHER.

&&

.NEAR TERM /THROUGH SUNDAY/...
STABLE CONDITIONS WILL PERSIST THROUGH EARLY TONIGHT AS HIGH
PRESSURE MOVES OFF THE EAST COAST. INCREASING LOW LEVEL MOISTURE
WITH THE SUPPORT OF A WEAK UPPER WAVE WILL PROVIDE CLOUD
DEVELOPMENT OVERNIGHT. SUFFICIENT FORCING FOR PRECIPITATION
REMAINS FURTHER WEST...THUS LOW POPS WERE MAINTAINED LATE TONIGHT.

BROAD UPPER LEVEL TROUGH APPROACHING FROM THE UPPER MIDWEST IS
EXPECTED TO DEEPEN BY SUNDAY. INSUFFICIENT CAPE DUE TO EXTENSIVE
CLOUD COVER...LIMITED DAYTIME HEATING...AND POOR MID LEVEL LAPS
RATES WILL OVERALL LIMIT THE COVERAGE AND LONGEVITY OF
THUNDERSTORMS. HOWEVER...THE POTENTIAL STILL EXISTS FOR LOW TOPPED
THUNDERSTORMS AS LOW LEVEL MOISTURE REMAINS ABUNDANT WHILE LOW
LEVEL LAPS RATES STEEPEN AHEAD AND ALONG OF THE SURFACE COLD
FRONT. DUE TO THE RELATIVELY DRY AIR ALOFT AND STRONG
SHEAR...SHOWERS WITH STRONG WIND GUSTS CAN BE EXPECTED ON SUNDAY.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
UPPER LEVEL TROUGH AXIS IS PREDICTED TO CROSS THE AREA SUNDAY
NIGHT. IN THE WAKE OF THE COLD FRONT...A STRONG INVERSION WILL SET
UP AS NORTHWEST FLOW DEVELOPS AND THEREFORE LAKE AND TERRAIN
ENHANCED SHOWERS/CLOUDS WILL PURSUE EARLY MONDAY MORNING MAINLY
NORTH OF I-76...BUT SINCE THE INVERSION LOWERS AND REMAINS
SHALLOW...STRATOCU DECK WILL LIKELY SUPERSEDE SHOWERS MUCH OF MONDAY.

SURFACE HIGH PRESSURE BUILDS MONDAY NIGHT BRINGING DRIER
CONDITIONS TO HELP WEAKEN THE INVERSION.

TEMPERATURES WILL BE COOLER THAN AVERAGE DURING THE PERIOD.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
ECMWF AND GFS ENSEMBLES REMAIN IN GENL AGRMNT WITH DEPICTIONS OF
DRY WEATHER FOR THE UPR OH REGION INTO THE WEEKEND AS BROAD RIDGE
IS BUILT OVR MUCH OF THE CONUS. DESPITE RECENT ECMWF DETERMINISTIC
TRENDS OF AN AMPLIFYING WEAKNESS OVR THE MID ATLANTIC STATES...SUB
CLIMO/DRY POPS WERE THUS MAINTAINED. TEMPS UNDR THIS PTN WOULD
MODERATE TO AT LEAST 5 DEGREES ABOVE THE AVGS...FORECAST FOR WHICH
WAS BASED ON PERSISTENCE AND THE LATEST WPC GUIDANCE.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
GRADUAL CONDITION DETERIORATION TO MVFR/LCL IFR CAN BE EXPECTED
LATE TNGT AND INTO SUNDAY AS A CDFNT APCHS FM THE W. ST DVLPMNT IN
THE WARM...MOIST FLOW UNDR THE INVERSION IS ANTICIPATED AS IS
ELEVATED SHWR DVLPMNT TWD MRNG. THE BTR CHC FOR IFR IS EXPECTED IN
THE MORE WIDESPREAD SHWRS AFTR DAYBREAK.

OUTLOOK.../SUNDAY NGT THROUGH THURSDAY/...
COLD ADVCTN OFF THE GREAT LAKES IS EXPECTED TO SPPRT MVFR STRATOCU
THRU MONDAY. THEREAFTER...GENL VFR IS ONLY EXPECTED TO BE
TARNISHED BY PERIDAWN FOG AND LCL ST.

&&

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

&&

$$

24/15



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