Severe Thunderstorm Warning 76, NWS Pittsburgh, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
349 PM EDT FRI JUN 4 2010

.SYNOPSIS...
A BOUNDARY WILL REMAIN STATIONARY ACROSS THE AREA THROUGH EARLY
SUNDAY...ALLOWING FOR AN UNSETTLED WEATHER PATTERN TO CONTINUE.
SHOWERS AND THUNDERSTORMS...SOME SEVERE...WILL BE POSSIBLE
THROUGH THIS PERIOD. THE BOUNDARY WILL DROP SOUTH OF THE AREA LATE
SUNDAY...WITH THE CHANCE FOR SHOWERS DIMINISHING EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THE AREA REMAINS IN A ZONAL FLOW WITH A FRONTAL BOUNDARY LINGERING
JUST NORTH OF THE PITTSBURGH METRO. WITH DEW POINTS IN THE MID TO
UPPER 60S...A WARM...MOIST AIR MASS REMAINS ACROSS THE REGION AS
SCATTERED CONVECTION CONTINUES TO DEVELOP. TWO OF THE STORMS IN
EASTERN OHIO HAVE EXHIBITED ROTATION THUS FAR...PRODUCING LARGE
HAIL. SEVERE THUNDERSTORM WARNINGS ARE ONGOING...AND RECENT
ROTATION PROMPTED A TORNADO WARNING. 0-1KM SHEAR AT 10-15KTS IS
LESS FAVORABLE FOR THE DEVELOPMENT...ALTHOUGH WITH THE BOUNDARY IN
THE VICINITY AND 0-6KM SHEAR OF 40-45KTS...THE TORNADO THREAT
CANNOT BE RULED OUT. IT STILL APPEARS THAT THE MAIN THREAT THIS
AFTERNOON WILL BE LARGE HAIL AND DAMAGING WINDS. INITIAL STORM
DEVELOPMENT SHOULD CONTINUE ALONG AND NORTH OF THE INTERSTATE 70
CORRIDOR AND THEN SPREAD FURTHER SOUTHWARD AS INSTABILITY
INCREASES ACROSS NORTH-CENTRAL WV.

THE SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR EASTERN OHIO
AND EVERYWHERE NORTH OF THE MASON- DIXON LINE. WITH PWATS NEAR 1.5
INCHES...FLASH FLOODING IS ALSO A CONCERN IF STORMS TRAIN IN
LOCATIONS ALONG THE BOUNDARY WHERE MUCH OF THE AREA WHICH HAS SEEN
SEVERAL INCHES OF RAINFALL OVER THE PAST FEW DAYS.

TONIGHT...AS DIURNAL CONVECTION DIMINISHES THE SEVERE THREAT
APPEARS THAT IT WILL SHIFT FURTHER NORTH OF PITTSBURGH CLOSER TO
THE INTERSTATE 80 CORRIDOR AS A 45 KT LLJ PUSHES ACROSS THE AREA.
WITH THIS IN MIND...THE DAMAGING WIND THREAT LOOKS TO INCREASE
WITH THE POSSIBILITY OF A MORE ORGANIZE LINE OR BOW ECHO
DEVELOPING. WITH HEAVY RAINFALL POSSIBLE...THIS AGAIN WILL KEEP THE
THREAT FOR FLASH FLOODING ACROSS THE NORTH IN PLACE.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
WITH THE LOW-LEVEL JET OVERNIGHT LIFTING NORTHEAST OF THE AREA
SATURDAY MORNING...CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
DIMINISH BRIEFLY BEFORE THE NEXT ROUND BEGINS SATURDAY AFTERNOON. SPC
HAS MUCH OF THE OHIO VALLEY HIGHLIGHTED IN A SLIGHT RISK. THE
BOUNDARY WILL REMAIN IN THE AREA...WITH A SHORT WAVE CROSSING THE
OHIO VALLEY SATURDAY AFTERNOON. THIS WILL RETURN THE SEVERE
THREAT...ESPECIALLY ACROSS EAST CENTRAL OHIO. ONCE AGAIN...SEVERE
HAIL...DAMAGING WINDS...AND FLASH FLOODING WILL BE CONCERNS AS
STORM MOVE OVER SIMILAR AREAS TO TODAY.

IT APPEARS THAT THE BEST THREAT FOR HEAVY RAINFALL ALONG WITH
SEVERE WEATHER WILL BE SATURDAY NIGHT AS A 60KT LOW-LEVEL JET AXIS
CROSSES THE AREA. THE FRONTAL BOUNDARY WILL SLIDE SLOWLY SOUTH OF
THE AREA WITH THUNDERSTORMS DIMINISHING TO SHOWERS BY SUNDAY
MORNING. WITH THE TROUGH AXIS PASSING THROUGH THE AREA...SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE SUNDAY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
WITH REASONABLE MODEL AGREEMENT...FORECAST IS A
HPC/GFSE BLEND SOLUTION. THE AXIS OF A BROAD 500MB TROUGH WILL BE
CENTERED ACROSS THE DELMARVA PENINSULA SUNDAY NIGHT WITH THE AREA IN
A NORTHWESTERLY MID-LEVEL FLOW LOCALLY. ANY LINGERING SHOWERS WILL
DIMINISH SUNDAY NIGHT AS HIGH PRESSURE AND A DEEPER LAYER OF DRY AIR
BUILDS IN FROM THE NORTHWEST. MONDAY AND TUESDAY SHOULD BE MOSTLY
DRY AS HIGH PRESSURE BUILDS INTO THE AREA.

GFS/ECMWF SOLUTIONS ARE IN AGREEMENT AS THE TROUGH MOVES EAST OF
THE AREA ON MONDAY...A COOLER MID-LEVEL NORTHWESTERLY FLOW WILL
ALLOW FOR TEMPERATURES AROUND 5 DEGREES BELOW NORMAL. AS THE LOW
APPROACHES FROM THE WEST...MORE OF A SOUTHERLY COMPONENT TO THE
FLOW WITH WAA WILL ALLOW FOR TEMPERATURES TO RETURN TO NORMAL
SEASONAL VALUES TUESDAY AND WEDNESDAY.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
THUNDERSTORMS DEVELOPING ALONG OLD BOUNDARY STRETCHING FROM NEAR PIT
WESTWARD TOO NEAR PHD.  STORMS IN EAST CENTRAL OHIO AROUND 18Z
REACHING WESTERN PA AROUND 20-21Z.  EXPECT SCATTERED IFR CONDITIONS
IN TSTMS THROUGH 00Z WITH ACTIVITY GRADUALLY DISSIPATING AFTER
THAT.

SECONDARY FRONT DROPS SOUTHEAST AFTER MIDNIGHT WITH ANOTHER ROUND OF
TSTMS PREDOMINANTLY IN NORTHWEST PA AFTER MIDNIGHT WITH WEAKENING
LINE OF STORMS MOVING SOUTHEAST ACROSS SW PA AROUND AROUND DAYBREAK.
SCATTERED STORMS REDEVELOP WITH POSSIBLE IFR CONDITIONS ACROSS
SOUTHWEST PA DURING THE AFTERNOON AND WESTWARD INTO EAST CENTRAL
OHIO ALONG STALLED BOUNDARY.

LOW PRESSURE WILL CROSS THE AREA OVER THE WEEKEND...WITH A WARM
MOIST AIR MASS ALLOWING FOR THE CHANCE OF SHOWERS AND THUNDERSTORMS
WITH POSSIBLE RESTRICTIONS SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE
BUILDS INTO REGION DURING THE DAY ON MONDAY WITH VFR CONDITIONS.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PITTSBURGH PA
311 PM EDT FRI JUN 4 2010

OHZ039>041-048>050-057>059-PAZ007>009-013>016-020>023-029>032-
WVZ001>004-051915-
TUSCARAWAS-CARROLL-COLUMBIANA-COSHOCTON-HARRISON-JEFFERSON OH-
MUSKINGUM-GUERNSEY-BELMONT-MERCER-VENANGO-FOREST-LAWRENCE-BUTLER-
CLARION-JEFFERSON PA-BEAVER-ALLEGHENY-ARMSTRONG-INDIANA-WASHINGTON-
WESTMORELAND-GREENE-FAYETTE-HANCOCK-BROOKE-OHIO-MARSHALL-
311 PM EDT FRI JUN 4 2010

...SEVERE THUNDERSTORM WATCH 254 IN EFFECT UNTIL 8 PM EDT THIS
EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL OHIO...NORTHWEST
PENNSYLVANIA...SOUTHWEST PENNSYLVANIA...WEST CENTRAL PENNSYLVANIA
AND NORTHERN PANHANDLE OF WEST VIRGINIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   SEVERE THUNDERSTORM WATCH.

THERE IS ALSO A CHANCE OF SEVERE THUNDERSTORMS TONIGHT. THE
PRIMARY THREAT WILL BE DAMANGING WINDS...WITH LARGE HAIL AND FLASH
FLOODING POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE IS A SLIGHT CHANCE FOR SEVERE WEATHER EARLY SATURDAY...AND
AGAIN SATURDAY NIGHT INTO SUNDAY. THE MAIN HAZARDS WILL BE
DAMAGING WINDS AND LARGE HAIL.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

MDZ001-OHZ068-069-WVZ012-021>023-041-051915-
GARRETT-NOBLE-MONROE-WETZEL-MARION-MONONGALIA-PRESTON-TUCKER-
311 PM EDT FRI JUN 4 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN MARYLAND...EAST
CENTRAL OHIO AND NORTHERN WEST VIRGINIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

THERE IS A CHANCE OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT. THE MAIN HAZARDS WILL BE DAMAGING WINDS AND LARGE HAIL.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

THERE IS A SLIGHT CHANCE FOR SEVERE WEATHER SATURDAY INTO SUNDAY.
THE MAIN HAZARDS WILL BE DAMAGING WINDS AND LARGE HAIL.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

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