Hail and Damaging Winds in Pennsylvania, July 17, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
220 PM EDT TUE JUL 17 2007

.SYNOPSIS...

A SERIES OF UPPER LEVEL DISTURBANCES WILL CROSS THE UPPER OHIO
VALLEY, MAINTAINING THE CHANCES FOR THUNDERSTORMS INTO EARLY FRIDAY.
DRY WEATHER UNDER COOL HIGH PRESSURE IS EXPECTED FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...

LOW PRES/REMNANT MCS CONTD TO ADVN ON THE WRN PERIMETER OF THE
CNTY WRNG AREA THIS AFTN WHILE WARM FRONT AND SURGING MSTR MOVED
ON THE SRN ZONES. 1ST PD POPS OUTSIDE OF LATE AFTN PCPN ADVCTN NR
ZZV WERE STRUCTURED WITH BEST NMBRS (LIKELY) CONFINED TO THE NRN
HALF OF THE CNTY WRNG AREA WHERE WARM FRONT IS EXPECTED TO CROSS
TO THIS EVE IN ADVN OF THE LOW. OVRNGT TAPER TO CHC/SCT NMBRS
WAS COMPLETED AS DIURNAL SPPRT IS LOST AND SHRTWV SHIFTS EWD.

NXT IN SERIES OF IMPULSES INTO THE BASE OF THE ERN CONUS TROF IS
LOOSELY TIMED FOR MIDDAY WED...HENCE POPS WERE ESCALATED TO LIKELY
NMBRS ACRS ALL ZONES FOR THIS FEATURE COMBINED WITH BEST HEATING AND
FOCUS PRVD BY MESOSCALE/OUTFLOW BNDRIES ALNG WITH CELLS MOVG OFF
SYNOPTIC FRONT MENTIONED ABOVE.

SVR THREAT RMNS SLIGHT FOR WED GIVEN TIMING UNCERTAINITIES OF
SHRTWV AND MAX INSTABILITY, HOWEVER SHEAR VALUES ASSOCIATED WITH
BNDRY LYR SW FLOW AND ZONAL TO NW ALOFT WL BE SUFFICIENT FOR A
CONTD SVR POTENTIAL WITH LARGE HAIL AND DAMAGING WIND GUSTS BEING
THE PRIMARY THREAT.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...

PTN REPEATS FOR THE SHRT TERM PDS WITH WED DISTURBANCE SHIFTING EWD
AT NGT.  THIS TIMING COMBINED WITH LOSS OF INSOLATION ALLOWS FOR
ANOTHER TAPER FM LIKELY NMBRS TO CHC/SCT OVRNGT.  GFS/NAM MDLS ARE
CONSISTENT IN DIGGING A MORE SIGNIFICANT SHRTWV ACRS THE GREAT LAKES
ON THU WITH THUNDERSTORM CHCS AGAIN INCRSG AFTR DAYBREAK.  HAVE THUS
INCRSD THU POPS TO LIKELY NMBRS AND MAINTAINED SVR WORDING IN THE
HWO PRODUCT...ALTHOUGH INSTABILITY MAY BE MARGINAL DUE TO WIDESPREAD
CLDINESS, MID LVL WNDS PROJECTIONS ARE MORE SIGNIFCANT WITH
ENVISIONED THREAT BEING MORE MCS-LIKE.

ASSOCIATED SFC CDFNT IS CURRENTLY TIMED FOR FRI. HAVE ALLOWED FOR
MORE RAPID DRYING WITH ONLY SLIGHT POPS LINGERING OVR THE RIDGE
ZONES BY FRI EVE AND WITH DECREASING CLDINESS EARLY ON SAT.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...

PRECIPITATION CHANCES WILL BE ENDING FOR THE WEEKEND AS HIGH
PRESSURE BUILDS UNDER OVRALL ERN CONUS TROF.  PTN WL FEATURE BLO
NORMAL TEMPS (APPRX 5 DEG) FOR THE WEEKEND FOLLOWED BY RECOVERY TO
NR NORMAL READINGS TO START THE NEW WEEK.  BUILDING RIDGE IN ADVN OF
WRN CONUS TROFFING WL SPPRT INCRSG WARMTH THEREAFTER.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...

WARM FRONT WITH DEWPOINTS IN MID 60S STRETCHES FROM NEAR TOLEDO OH
TO PARKERSBURG WV. WARM FRONT FORECAST TO CONTINUE NORTHEAST
OVERNIGHT ACROSS CWA.  DISSIPATING MCS MOVING SOUTHEAST ACROSS
INDIANA AT 17Z WILL CONTINUE TO PUSH MID LEVEL CLOUDS ACROSS CWA
THIS EVENING.

TSTMS CURRENTLY MOVING SOUTH OF CWA IN HIGHER DEWPOINTS.  WITH
HEATING SCT TSTMS POSSIBLE IN EAST CENTRAL OHIO BY 21Z AND WESTERN
PA BY 00Z.

GENERALLY VFR CONDITIONS OUTSIDE OF THUNDERSTORMS THROUGH 06Z.
COMBINATION OF INCREASING DEWPOINTS AND LOW LEVEL MOISTURE LEFT OVER
FROM SHOWERS/THUNDERSTORMS EARLY TONIGHT WILL PRODUCE MFR VSBYS
AFTER 06Z.  VSBYS OF 3 -5 MILES EXPECTED THROUGH 16Z TOMORROW.

SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE FOR WEDNESDAY,
THURSDAY, AND EARLY FRIDAY AS FRONTAL ZONE REMAINS ACROSS THE
FORECAST AREA. HIGH PRESSURE BUILDING IN BEHIND THE FRONT SATURDAY
WILL BRING DRY WEATHER AND VFR CONDITIONS THROUGH SUNDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...

MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

15/05

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
1235 PM EDT TUE JUL 17 2007

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-
029>032-WVZ001>004-012-021>023-041-181645-
GARRETT-TUSCARAWAS-CARROLL-COLUMBIANA-COSHOCTON-HARRISON-
JEFFERSON OH-MUSKINGUM-GUERNSEY-BELMONT-NOBLE-MONROE-MERCER-VENANGO-
FOREST-LAWRENCE-BUTLER-CLARION-JEFFERSON PA-BEAVER-ALLEGHENY-
ARMSTRONG-INDIANA-WASHINGTON-WESTMORELAND-GREENE-FAYETTE-HANCOCK-
BROOKE-OHIO-MARSHALL-WETZEL-MARION-MONONGALIA-PRESTON-TUCKER-
1235 PM EDT TUE JUL 17 2007

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

.DAY ONE...THIS AFTERNOON AND TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SHOWERS AND THUNDERSTORMS ARE LIKELY ARE WEDNESDAY AND THURSDAY AS
A SERIES OF UPPER DISTURBANCES CROSS THE REGION. THERE IS A
SLIGHT RISK OF THAT SOME THUNDERSTORM CELLS COULD REACH SEVERE
LEVELS ON BOTH DAYS. THE PRIMARY SEVERE WEATHER THREATS WILL BE
DAMAGING WINDS AND LARGE HAIL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ON WEDNESDAY AND THURSDAY.

15

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
432 PM EDT TUE JUL 17 2007

OHZ057-172115-
MUSKINGUM OH-
432 PM EDT TUE JUL 17 2007

...THUNDERSTORMS TO MOVE THROUGH MUSKINGUM COUNTY...

AT 430 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR IN PITTSBURGH
INDICATED STRONG THUNDERSTORMS 4 MILES SOUTH OF EAST FULTONHAM...
MOVING EAST AT 25 MPH.

SOME LOCATIONS THAT WILL BE IMPACTED BY THESE STORMS INCLUDE...
  BLUE ROCK STATE PARK...CANNELVILLE...CHANDLERSVILLE...PHILO...
  DUNCAN FALLS...EAST FULTONHAM AND HIGH HILL.

FREQUENT LIGHTNING AND WIND GUSTS TO 40 MPH ARE POSSIBLE. WHEN
THREATENING WEATHER APPROACHES, MOVE INDOORS.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
508 PM EDT TUE JUL 17 2007

OHZ058-172200-
GUERNSEY OH-
508 PM EDT TUE JUL 17 2007

...THUNDERSTORMS TO MOVE THROUGH GUERNSEY COUNTY...

AT 505 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR IN PITTSBURGH
INDICATED STRONG THUNDERSTORMS 7 MILES SOUTHWEST OF CAMBRIDGE MOVING
EAST AT 35 MPH.

SOME LOCATIONS THAT WILL BE IMPACTED BY THESE STORMS INCLUDE...
BYESVILLE...CAMBRIDGE...OLD WASHINGTON AND SALT FORK STATE PARK.

FREQUENT LIGHTNING AND WIND GUSTS TO 40 MPH ARE POSSIBLE.  WHEN
THREATENING WEATHER APPROACHES, MOVE INDOORS.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
740 PM EDT TUE JUL 17 2007

PAZ021-180015-
ALLEGHENY PA-
740 PM EDT TUE JUL 17 2007

...THUNDERSTORMS MOVING THROUGH ALLEGHENY COUNTY...

AT 740 PM EDT NATIONAL WEATHER SERVICE DOPPLER RADAR IN PITTSBURGH
INDICATED STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM NEAR
GIBSONIA TO PITTSBURGHS NORTH SIDE...MOVING EAST AT 30 MPH.

SOME LOCATIONS THAT WILL BE IMPACTED BY THESE STORMS INCLUDE...FOX
CHAPEL...NATRONA HEIGHTS...PENN HILLS...PLUM...RUSSELLTON AND
SPRINGDALE.

SMALL HAIL AND WIND GUSTS TO 45 MPH ARE POSSIBLE.  ALSO, UP TO ONE
INCH OF RAIN MAY FALL IN SHORT PERIOD OF TIME.

PLEASE REPORT HAIL...STRONG WINDS OR WIND DAMAGE TO THE NATIONAL
WEATHER SERVICE BY CALLING TOLL FREE...1-877-633-6772.

INTENSE LIGHTNING IS REPORTED WITH THIS STORM. IF OUTDOORS...STAY
AWAY FROM ISOLATED HIGH OBJECTS SUCH AS TREES. MOVE INDOORS IF
POSSIBLE. WHEN INDOORS...STAY AWAY FROM WINDOWS AND DOORS AND AVOID
USING TELEPHONES UNLESS IT IS AN EMERGENCY. TRY TO UNPLUG UNNECESSARY
ELECTRICAL APPLIANCES BEFORE THE THUNDERSTORM APPROACHES.