Severe Thunderstorm Warning 152, NWS State College, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
729 PM EDT THU AUG 20 2009

.SYNOPSIS...
MAINLY AFTERNOON SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
CONTINUE THROUGH FRIDAY...AND SOME THUNDERSTORMS WILL BE STRONG TO
SEVERE. A COLD FRONT WILL MOVE THROUGH LATE FRIDAY AND STALL OUT
BEFORE REACHING THE MID ATLANTIC COAST SATURDAY...INTERACTING WITH
DEEP TROPICAL MOISTURE ASSOCIATED WITH HURRICANE BILL...AND HEAVY
RAINFALL WILL BE POSSIBLE ACROSS EASTERN PENNSYLVANIA ALONG THE
STALLED FRONTAL BOUNDARY THROUGH SATURDAY NIGHT. THEN COOLER
TEMPERATURES AND LESS HUMID CONDITIONS WILL FOLLOW SUNDAY INTO
NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...
STRONG TO SEVERE STORMS HAVE FIRED ACROSS THE LOWER SUSQ DURING THE
PAST FEW HOURS...LINING UP NICELY WHERE THE 06Z AND 12Z NAM HAD
ITS JUICED- UP MU CAPES OF 2500-3000 J/KG.  MID LVL DISTURBANCE
THAT TRACKED NEWD FROM THE CENTRAL APPALACHIANS TODAY SERVING AS THE
TRIGGERING MECHANISM...AND A SECOND ROUND OF STORMS ARE LIKELY TO
FIRE WITH A SECOND DISTURBANCE...CURRENTLY ALONG A BFD...AOO...HGR
LINE. ALTHOUGH MID LVL LAPSE RATES REMAIN WEAK OWING TO A VERY MOIST
DEEP LYR AIRMASS...VERY STEEP LOW LEVEL LAPSE RATES WILL CONTRIBUTE
TO THE POTENTIAL FOR DAMAGING WIND GUSTS IN LOCALIZED DOWNBURSTS.
INCREASING BULK SHEAR MAY ALSO BE SUPPORTIVE FOR A FEW ORGANIZED
BOWING SEGMENTS WITH THE PRIMARY THREAT AGAIN BEING DAMAGING WINDS.

CVRG OF SHWRS/TSTORMS WILL DEC LATER TONIGHT WITH THE LOSS OF
HEATING. ABV NORMAL MSTR LVLS WILL KEEP LOWS MUGGY IN THE MID 60S
TO LOW 70S...THAT WILL LEAD TO DEVELOPMENT OF PATCHY DENSE FOG.

THE MAIN SYNOPTIC COLD FRONT WILL APPROACH WESTERN PA EARLY FRIDAY.
AHEAD OF THIS FEATURE...MODEL GUID SUGGESTS UPSTREAM TSTORM CLUSTERS
/PERHAPS ONGOING AT THE START OF THE PD IN THE OH VLY/ WILL MOVE
NNEWD INTO THE LWR GRT LKS DURING THE AFTN...ACCOMPANIED BY POTENT
SHORTWAVE ROTATING AROUND THE BASE OF THE CLOSED H5 LOW OVR
ONTARIO. SREF SHOWS THE BEST CAPES/EHI OVR SE PA INVOF OF LEE SFC
TROUGH...HOWEVER SPC DY2 OUTLOOK /SLGT RISK/ SUGGESTS POTENTIAL
FOR SVR MAY BE GREATER FURTHER N/W OVR THE CENTRAL MTNS WHERE DEEP
LYR SHEAR WILL BE MAXIMIZED DURING PEAK HEATING.

THE STRONG COLD FRONT WILL BEGIN TO SLOW...AND TEMPORARILY STALL OUT
ACROSS FAR ERN PENN LATER FRI NIGHT INTO SAT NIGHT AS THE UPPER
TROUGH SHARPENS AND POWERFUL HURRICANE BILL SWEEPS NORTHWARD SEVERAL
HUNDRED NM EAST OF THE MID ATLANTIC COAST.

EXPECT HIGH POPS ACROSS THE SUSQ VALLEY AND PTS EAST THROUGH MOST OF
THIS PERIOD...THOUGH THERE WILL BE THE TYPICAL DECREASE IN NOCTURNAL
INTENSITY TO THE TSRA AND ASSOCIATED RAINFALL RATES.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
THE MAIN SYNOPTIC COLD FRONT WILL APPROACH WESTERN PA EARLY
FRIDAY. AHEAD OF THIS FEATURE...MODEL GUID SUGGESTS UPSTREAM TSTORM
CLUSTERS /PERHAPS ONGOING AT THE START OF THE PD IN THE OH VLY/
WILL MOVE NNEWD INTO THE LWR GRT LKS DURING THE AFTN...ACCOMPANIED
BY POTENT SHORTWAVE ROTATING AROUND THE BASE OF THE CLOSED H5 LOW
OVR ONTARIO. SREF SHOWS THE BEST CAPES/EHI OVR SE PA INVOF OF LEE
SFC TROUGH...HOWEVER SPC DY2 OUTLOOK /SLGT RISK/ SUGGESTS
POTENTIAL FOR SVR MAY BE GREATER FURTHER N/W OVR THE CENTRAL MTNS
WHERE DEEP LYR SHEAR WILL BE MAXIMIZED DURING PEAK HEATING.

THE STRONG COLD FRONT WILL BEGIN TO SLOW...AND TEMPORARILY STALL OUT
ACROSS FAR ERN PENN LATER FRI NIGHT INTO SAT NIGHT AS THE UPPER
TROUGH SHARPENS AND POWERFUL HURRICANE BILL SWEEPS NORTHWARD SEVERAL
HUNDRED NM EAST OF THE MID ATLANTIC COAST.

EXPECT HIGH POPS ACROSS THE SUSQ VALLEY AND PTS EAST THROUGH MOST OF
THIS PERIOD...THOUGH THERE WILL BE THE TYPICAL DECREASE IN NOCTURNAL
INTENSITY TO THE TSRA AND ASSOCIATED RAINFALL RATES.

LATER SHIFTS WILL HAVE TO FOCUS ON A POSSIBLE FLOOD WATCH FOR AT
LEAST THE SMALLER STREAMS AND CREEKS NEAR...AND ESPECIALLY TO THE
EAST OF THE LOWER/MID SUSQ VALLEY AS OPERATIONAL NAM/GFS SHOWS 36 HR
QPF IN EXCESS OF 2 INCHES (SUPPORTED BY THE SUPER ENSEMBLES PWATS
OF 45 MM OR HIGHER...AND ITS ROUGHLY 60 PERCENT CHC OF OVER 1 INCH
OF QPF THERE). WOULDNT BE SURPRISED TO SEE ISOLATED 3-4 INCH
AMOUNTS FROM SCHUYLKILL COUNTY SOUTH INTO OUR FAR SERN ZONES BY SAT
NIGHT.

PRECIP IN THE FORM OF SCATTERED SHOWERS AND TSRA WILL BE MUCH
LIGHTER (UNDER 0.75) ACROSS THE WRN HALF OF THE CWA WHERE A
MEAN...WESTERLY LLVL FLOW WILL DROP PWATS TO NEAR NORMAL WITH ONLY
MARGINALLY STEEP MID LVL LAPSE RATES AS THE MAIN UPPER TROUGH AXIS
APPROACHES FROM THE OHIO VALLEY.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
QUIETER WEATHER WILL BE THE RULE FOR THE PERIOD SUNDAY THROUGH
THURSDAY...ESPECIALLY COMPARED TO THE RECENT WEEK. THE COLD FRONT
THAT WILL MOVE THROUGH FRI/SAT WILL BE EAST OF THE REGION AND
HURRICANE BILL WILL HAVE SLID BY OFFSHORE. SURFACE HIGH PRESSURE
WILL BE BUILDING IN UNDER A WEAK MID LEVEL TROUGH...BRINGING DRIER
AND COOLER CONDITIONS WITH A DECENT AMOUNT OF CLOUDINESS. THERE
WILL BE A CHANCE FOR A SHOWER OR TSTORM ON SUNDAY...BUT THE FIRST
PART OF NEXT WEEK LOOKS DRY. NEXT WAVE LOOKS TO ARRIVE ON THU WITH
INCREASING RAIN CHANCES.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...

SHORT TERM CONCERNS CENTER AROUND THE EVOLUTION OF A LINE OF STRONG
TO SEVERE THUNDERSTORMS ENTERING WESTERN PA AT THIS HOUR. BEST
CHANCE OF LOWERING CONDITIONS WITH THUNDER THROUGH ABOUT MIDNIGHT
WILL BE OVER THE WESTERN 1/3 OR SO OF MY FCST AREA...WITH ACTIVITY
GRADUALLY WEAKENING AFTER SUNDOWN.

AS LOW LEVEL MOISTURE REMAINS IN PLACE...LOOK FOR PATCHY LOW
CLOUDS AND DENSE FOG TO DEVELOP LATER IN THE EVENING ACROSS THE
REGION. AFTER THE FOG MIXES OUT AS WINDS PICK UP TO NEAR 10KT
STATEWIDE FRIDAY MORNING...LOOK FOR ANOTHER ROUND OF GUSTY
SHRA/TSRA AS A COLD FRONT MOVES THROUGH THE REGION.

OUTLOOK...
SAT...MAINLY MVFR IN SHRA/TSRA...FOG...AND HZ.
SUN-TUE...MORNING FOG...THEN MAINLY VFR.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

SYNOPSIS...LAMBERT/RXR
NEAR TERM...LAMBERT/DICKEY
SHORT TERM...LAMBERT/DICKEY
LONG TERM...RXR
AVIATION...LA CORTE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
658 PM EDT THU AUG 20 2009

PAZ004>006-010-011-017-024-033-212300-
WARREN-MCKEAN-POTTER-ELK-CAMERON-CLEARFIELD-CAMBRIA-SOMERSET-
658 PM EDT THU AUG 20 2009

...SEVERE THUNDERSTORM WATCH 723 IN EFFECT UNTIL 2 AM EDT FRIDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...TONIGHT.

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

   SEVERE THUNDERSTORM WATCH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ON FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

PAZ012-018-019-025>028-034>037-041-042-045-046-049>053-056>059-
063>066-212300-
NORTHERN CLINTON-NORTHERN CENTRE-SOUTHERN CENTRE-BLAIR-HUNTINGDON-
MIFFLIN-JUNIATA-BEDFORD-FULTON-FRANKLIN-TIOGA-NORTHERN LYCOMING-
SULLIVAN-SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR-
NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-SCHUYLKILL-LEBANON-CUMBERLAND-
ADAMS-YORK-LANCASTER-
658 PM EDT THU AUG 20 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...TONIGHT.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING
ACROSS CENTRAL PENNSYLVANIA. THE PRIMARY THREAT WILL BE DAMAGING
WIND GUSTS. LOCALLY HEAVY DOWNPOURS WILL ALSO BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ON FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE STATE COLLEGE PA
442 PM EDT THU AUG 20 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     TSTM WND DMG     2 S LIVERPOOL           40.54N 76.99W
08/20/2009                   PERRY              PA   COUNTY OFFICIAL

            911 CENTER REPORTED TREES DOWN ALONG HUNTERS VALLEY ROAD
            IN BUFFALO TOWNSHIP.

0330 PM     TSTM WND DMG     5 ESE HALIFAX           40.44N 76.85W
08/20/2009                   DAUPHIN            PA   COUNTY OFFICIAL

            911 CENTER REPORTED TREES ON WIRES IN MIDDLE PAXTON
            TOWNSHIP.

&&

MACH

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE STATE COLLEGE PA
454 PM EDT THU AUG 20 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     TSTM WND DMG     2 S LIVERPOOL           40.54N 76.99W
08/20/2009                   PERRY              PA   COUNTY OFFICIAL

            911 CENTER REPORTED TREES DOWN ALONG HUNTERS VALLEY ROAD
            IN BUFFALO TOWNSHIP.

0330 PM     TSTM WND DMG     5 ESE HALIFAX           40.44N 76.85W
08/20/2009                   DAUPHIN            PA   COUNTY OFFICIAL

            911 CENTER REPORTED TREES ON WIRES IN MIDDLE PAXTON
            TOWNSHIP.

0435 PM     TSTM WND DMG     LANCASTER               40.04N 76.30W
08/20/2009                   LANCASTER          PA   EMERGENCY MNGR

            TREES DOWN IN THE CITY OF LANCASTER.

&&

MACH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
515 PM EDT THU AUG 20 2009

PAZ026>028-036-056-202215-
FRANKLIN PA-HUNTINGDON PA-JUNIATA PA-MIFFLIN PA-PERRY PA-
515 PM EDT THU AUG 20 2009

...A STRONG THUNDERSTORM WILL AFFECT NORTH CENTRAL FRANKLIN...SOUTH
CENTRAL MIFFLIN...SOUTHEASTERN HUNTINGDON...SOUTHWESTERN JUNIATA AND
SOUTHWESTERN PERRY COUNTIES...

AT 515 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 18 MILES NORTHWEST
OF SHIPPENSBURG...MOVING NORTHEAST AT 20 MPH.

WIND GUSTS TO 40 MPH AND PEA-SIZED HAIL ARE POSSIBLE WITH THIS STORM.

THIS STORM WILL BE NEAR DOYLESBURG AROUND 530 PM...BIG SPRING STATE
PARK AROUND 545 PM...PERULACK AROUND 555 PM...BLACKLOG AROUND 605
PM...BLAIN AROUND 610 PM AND HONEY GROVE AROUND 615 PM.

THIS WILL IMPACT THE FOLLOWING MAJOR ROADS...ROUTE 22/522...ROUTE
522.

LAT...LON 4061 7760 4044 7733 4012 7779 4019 7792

EXPERIMENTAL

FORECASTER: DEVOIR

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
517 PM EDT THU AUG 20 2009

PAZ036-063-202215-
CUMBERLAND PA-FRANKLIN PA-
517 PM EDT THU AUG 20 2009

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL FRANKLIN AND WEST
CENTRAL CUMBERLAND COUNTIES...

AT 516 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 7 MILES WEST OF
CHAMBERSBURG...MOVING NORTHEAST AT 20 MPH.

WIND GUSTS TO 40 MPH AND PEA-SIZED HAIL ARE POSSIBLE WITH THIS STORM.

THIS STORM WILL BE NEAR UPPER STRASBURG AROUND 535 PM...ROXBURY
AROUND 545 PM...ORRSTOWN AROUND 550 PM...SHIPPENSBURG AROUND 555 PM
AND NEWBURG AROUND 605 PM.

THIS WILL IMPACT THE PENNSYLVANIA TURNPIKE BETWEEN MILE MARKERS 197
AND 209.

THIS WILL ALSO IMPACT THE FOLLOWING MAJOR ROADS...ROUTE 11...ROUTE
30.

LAT...LON 3996 7784 4022 7765 4023 7762 4020 7761
      4019 7760 4021 7757 4023 7753 4013 7738
      3990 7778

EXPERIMENTAL

FORECASTER: DEVOIR

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE STATE COLLEGE PA
643 PM EDT THU AUG 20 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0300 PM     TSTM WND DMG     2 S LIVERPOOL           40.54N 76.99W
08/20/2009                   PERRY              PA   COUNTY OFFICIAL

            911 CENTER REPORTED TREES DOWN ALONG HUNTERS VALLEY ROAD
            IN BUFFALO TOWNSHIP.

0330 PM     TSTM WND DMG     5 ESE HALIFAX           40.44N 76.85W
08/20/2009                   DAUPHIN            PA   COUNTY OFFICIAL

            911 CENTER REPORTED TREES ON WIRES IN MIDDLE PAXTON
            TOWNSHIP.

0335 PM     FUNNEL CLOUD     3 NE MIDDLETOWN         40.23N 76.69W
08/20/2009                   DAUPHIN            PA   BROADCAST MEDIA

            TV METEOROLOGIST RECIEVED PHOTO OF FUNNEL CLOUD TAKEN BY
            SPOTTER IN LOWER SWATARA TOWNSHIP.

0435 PM     TSTM WND DMG     LANCASTER               40.04N 76.30W
08/20/2009                   LANCASTER          PA   EMERGENCY MNGR

            TREES DOWN IN THE CITY OF LANCASTER.

0500 PM     TSTM WND DMG     LANCASTER               40.04N 76.30W
08/20/2009                   LANCASTER          PA   BROADCAST MEDIA

            TV METEOROLOGIST REPORTED THAT POWER COMPANY HAD 5200
            REPORTS OF OUTAGES ACROSS LANCASTER COUNTY.

&&

MACH

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
757 PM EDT THU AUG 20 2009

PAZ004-005-010-210030-
ELK PA-MCKEAN PA-WARREN PA-
757 PM EDT THU AUG 20 2009

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN ELK...SOUTHEASTERN
WARREN AND WESTERN MCKEAN COUNTIES...

AT 756 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 22 MILES NORTH OF
CLARION...MOVING NORTHEAST AT 25 MPH.

WIND GUSTS TO 40 MPH AND BRIEF HEAVY DOWNPOURS ARE POSSIBLE WITH
THIS STORM.

THIS STORM WILL BE NEAR SHEFFIELD AROUND 830 PM.

THIS WILL IMPACT THE FOLLOWING MAJOR ROADS...ROUTE 6...ROUTE 219...
STATE ROAD 59...STATE ROAD 66.

LAT...LON 4171 7854 4156 7896 4162 7898 4162 7929
      4163 7930 4200 7888

EXPERIMENTAL

FORECASTER: DEVOIR