Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 186, NWS Pittsburgh, PA

July 29, 2011Fayette County, Pennsylvania; Preston County, West Virginia

NWS Pittsburgh, PA issued this severe thunderstorm warning at Jul 29, 2011, 5:54 PM EDT for Fayette County, Pennsylvania; Preston County, West Virginia. It was in force for 51 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 29, 2011, 5:54 PM EDT (21:54 UTC)
Expired: Jul 29, 2011, 6:45 PM EDT
In force: 51 min
Issued by: NWS Pittsburgh, PA
Area: Storm-based polygon

Counties Fayette County, PA, Preston County, WV

The radar

The Pittsburgh radar (KPBZ), 105 km from the middle of the area, began a volume at 21:53 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 9.9 hours before the alert went out and 88 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 587 J/kg
Mixed-layer CIN: -44 J/kg
Mixed-layer LCL: 1121 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -39 m²/s²
0-3 km storm-relative helicity: 11 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -0.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Pittsburgh, PA wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 29, 4:33 PM EDT, 1 hour 21 minutes earlier.

Area forecast discussion, Jul 29, 4:33 PM EDT, 1 hour 21 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
433 PM EDT FRI JUL 29 2011

.SYNOPSIS...
A COLD FRONT WILL BRING THUNDERSTORMS OVERNIGHT FOLLOWED BY LESS
HUMID CONDITIONS FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH SATURDAY/...
A COLD FRONT ACROSS LAKE ERIE THIS AFTERNOON WILL MOVE SOUTH
OVERNIGHT WITH SHOWERS AND THUNDERSTORMS ACROSS THE REGION AHEAD
OF THE FRONT. WHILE 0-6KM SHEAR IS WEAK CAPES TO 2500 J/KG WILL
LIKELY ALLOW FOR STRONG STORMS WITH AN ISOLATED SEVERE STORM POSSIBLE.
HAVE LOWERED POPS FROM PITTSBURGH NORTH AS MAIN LINE OF CONVECTION
HAS FIRED ALONG OUTFLOW BOUNDARY WELL SOUTH OF FRONT. AS FRONT
SAGS SOUTH THUNDERSTORMS WILL DIMINISH OVERNIGHT WITH DRIER AIR
WORKING INTO THE NORTH TOWARD DAYBREAK SATURDAY AND ACROSS THE
REMAINDER OF REGION BY AFTERNOON. HEAT ADVISORY WILL BE MAINTAINED
UNTIL CLOUDS AND CONVECTION LOWER TEMPS EARLY THIS EVENING.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL DOMINATE INTO SUNDAY NIGHT WITH LOWER
DEW POINTS AND TEMPERATURES AVERAGING JUST ABOVE NORMAL. MODELS
AGREE ON A WEAK UPPER IMPULSE MOVING SOUTHEAST IN NORTHWEST FLOW
ALOFT MONDAY FOR A SLIGHT CHANCE OF THUNDERSTORMS. .

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
THE FORECAST PERIOD BEGINS WITH GFS/ECMWF AGREEMENT THAT A DEEP
RIDGE WILL BE CENTERED ACROSS THE CENTRAL PLAINS WITH A CLOSED LOW
OVER QUEBEC. IN BETWEEN THESE TWO FEATURES, THE UPPER OHIO VALLEY
WILL BE IN A NORTHWESTERLY FLOW THROUGH EARLY THURSDAY. HIGH
PRESSURE WILL MOVE ACROSS THE AREA ON TUESDAY, WITH A DRY FORECAST
UNTIL EARLY WEDNESDAY. IN ADVANCE OF AN APPROACHING FRONT, THE AREA
WILL BE IN A WARM AND MOIST AIR MASS WITH THE CHANCE OF
THUNDERSTORMS DURING THE DAY ON WEDNESDAY. TEMPERATURES WILL BE
CONSISTENTLY A FEW DEGREES ABOVE NORMAL VALUES THROUGH WEDNESDAY.

THE BROAD RIDGE ACROSS THE CENTRAL PLAINS WILL EXTEND EASTWARD INTO
THE SOUTHEAST FOR THURSDAY AND FRIDAY. THIS WILL ALLOW FOR MORE OF A
ZONAL FLOW ACROSS THE AREA FOR THE END OF THE WEEK. THE MODELS
DIVERGE WITH THE SURFACE PATTERN ON THURSDAY. WITH A WEAK FRONTAL
BOUNDARY IN THE VICINITY OF THE AREA, FORECAST IS FOR SCHC-CHC POPS
TO END THE WEEK. TEMPERATURES WILL BE NEAR NORMAL VALUES FOR THE END
OF THE WEEK.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
A COLD FRONT WILL DROP SOUTHEAST ACROSS THE TERMINALS THROUGH THE
TAF PERIOD. SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON
INTO THE EVENING AND SLIDE SOUTHEASTWARD OVERNIGHT. TEMPO GROUPS
ARE FORECAST ACROSS THE TERMINALS FOR THUNDERSTORMS WITH MVFR
RESTRICTIONS. A FEW OF THE STORMS MAY BE STRONG TO SEVERE WITH
GUSTY WINDS. IFR AND LOWER RESTRICTIONS ARE POSSIBLE IN LOCALIZED
HEAVIER STORMS. WINDS WILL BE OUT OF THE SOUTHWEST THIS AFTERNOON
AT 10-15KTS WITH GUSTS TO 20-25KTS.

SHOWERS AND STORMS WILL PUSH SOUTHEAST AND DECREASE IN COVERAGE
AND INTENSITY OVERNIGHT. LINGERING LOW-LEVEL MOISTURE WILL ALLOW
FOR MVFR CEILINGS TO DEVELOP AT KZZV/KMGW/KHLG OVERNIGHT. WITH
CLEARING AT THE REMAINING TERMINALS TO THE NORTH, MVFR VISIBILITY
RESTRICTIONS ARE POSSIBLE WITH FOG. IFR AND LOWER RESTRICTIONS
CANNOT BE RULED OUT NEAR DAWN.

VFR CONDITIONS WILL RETURN SATURDAY MORNING AS HIGH PRESSURE AND A
DEEP LAYER OF DRY AIR BUILD IN FROM THE NORTHWEST.

OUTLOOK /SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BUILD INTO THE AREA AND ALLOW FOR VFR CONDITIONS
TO PREVAIL MOSTLY ACROSS THE TERMINALS SUNDAY THROUGH TUESDAY. THE
EXCEPTION WILL BE FOR RESTRICTIONS WITH FOG DURING THE PRE-DAWN
HOURS EACH MORNING. A LOW PRESSURE SYSTEM WILL CROSS THE AREA ON
WEDNESDAY AND RETURN THE CHANCE OF SHOWERS AND THUNDERSTORMS WITH
RESTRICTIONS.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR OHZ048-057>059-
     068-069.
PA...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR PAZ031.
WV...HEAT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR WVZ003-004-012-
     021-022.

&&

Hazardous weather outlook, Jul 29, 5:23 PM EDT, 31 minutes before

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In the hours before

Special weather statement, Jul 29, 4:42 PM EDT, 1 hour 12 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
442 PM EDT FRI JUL 29 2011

PAZ029-WVZ002-003-292115-
BROOKE WV-OHIO WV-WASHINGTON PA-
442 PM EDT FRI JUL 29 2011

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN OHIO...SOUTHEASTERN
BROOKE AND SOUTHERN WASHINGTON COUNTIES...

AT 438 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 4 MILES SOUTHEAST
OF BETHANY...MOVING EAST AT 30 MPH.

WIND GUSTS TO 50 MPH ARE POSSIBLE WITH THIS STORM. VERY HEAVY RAIN
WILL FALL FROM THIS STORM...AND WILL CAUSE WATER TO POND ON ROADS AND
QUICKLY FILL ROADSIDE DITCHES AND SMALL STREAMS.  EXPECT INTENSE
LIGHTNING FROM THIS STORM. DO NOT STAY IN THE OPEN NOR SEEK SHELTER
UNDER TREES WHEN LIGHTNING THREATENS...MOVE INDOORS WHEN A
THUNDERSTORM APPROACHES.

SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE...
  CLAYSVILLE...         ENTERPRISE...         WASHINGTON...
  MARIANNA...           BENTLEYVILLE...

PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...877-633-6772...WHEN YOU CAN DO SO SAFELY.

LAT...LON 3998 8001 3998 8005 4001 8005 3999 8009
      3999 8015 4001 8017 4000 8028 4002 8030
      4001 8031 4002 8044 4006 8057 4027 8055
      4020 7992

Local storm report, Jul 29, 4:56 PM EDT, 58 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
456 PM EDT FRI JUL 29 2011

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

0450 PM     TSTM WND DMG     CAMBRIDGE               40.02N  81.59W
07/29/2011                   GUERNSEY           OH   911 CALL CENTER

            COUPLE OF TREES DOWN ON GASTON AVE

&&

EVENT NUMBER PBZ1101005

RG

Special weather statement, Jul 29, 5:00 PM EDT, 54 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PITTSBURGH PA
500 PM EDT FRI JUL 29 2011

PAZ073>076-292215-
FAYETTE PA-FAYETTE RIDGES PA-WESTMORELAND PA-WESTMORELAND RIDGES PA-
500 PM EDT FRI JUL 29 2011

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN FAYETTE AND SOUTH
CENTRAL WESTMORELAND COUNTIES...

AT 500 PM EDT...A STRONG THUNDERSTORM WAS LOCATED 5 MILES EAST OF
PERRYOPOLIS...MOVING EAST AT 25 MPH.

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

SOME LOCATIONS THAT WILL BE IMPACTED INCLUDE...
  WALTERSBURG...        PERRYOPOLIS...        DUNBAR...
  CONNELLSVILLE...      MOUNT PLEASANT...     OHIOPYLE...
  DONEGAL...            SEVEN SPRINGS...

PLEASE REPORT SIGNIFICANT WEATHER TO THE NATIONAL WEATHER SERVICE BY
CALLING TOLL FREE...877-633-6772...WHEN YOU CAN DO SO SAFELY.

LAT...LON 3995 7935 3990 7940 3983 7942 3998 7983
      4020 7970 4013 7925

Special weather statement, Jul 29, 5:07 PM EDT, 47 minutes before

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Local storm report, Jul 29, 5:40 PM EDT, 14 minutes before

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Special weather statement, Jul 29, 5:46 PM EDT, 8 minutes before

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The office that day

Everything else NWS Pittsburgh, PA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 28, 8:47 PM EDT	Special Weather Statement	PBZ	Armstrong, Westmoreland	58 min
Jul 28, 11:01 PM EDT	Special Weather Statement	PBZ	Armstrong	29 min
Jul 29, 1:19 PM EDT	Heat Advisory	PBZ	Greene	5 hr
Jul 29, 2:17 PM EDT	Special Weather Statement	PBZ	Indiana	28 min
Jul 29, 2:21 PM EDT	Special Weather Statement	PBZ	Beaver	24 min
Jul 29, 4:39 PM EDT	Special Weather Statement	PBZ	Westmoreland	51 min
Jul 29, 4:42 PM EDT	Special Weather Statement	PBZ	Washington	33 min
Jul 29, 4:50 PM EDT	Severe Thunderstorm Warning	PBZ	Indiana, Westmoreland	40 min
Jul 29, 5:00 PM EDT	Special Weather Statement	PBZ	Fayette	75 min
Jul 29, 5:07 PM EDT	Special Weather Statement	PBZ	Greene	83 min
Jul 29, 3:38 PM EDT	Special Weather Statement	PBZ	Coshocton	22 min
Jul 29, 3:47 PM EDT	Severe Thunderstorm Warning	PBZ	Carroll, Harrison, Tuscarawas	43 min
Jul 29, 4:04 PM EDT	Special Weather Statement	PBZ	Coshocton	26 min
Jul 29, 4:26 PM EDT	Special Weather Statement	PBZ	Guernsey	34 min
Jul 29, 4:37 PM EDT	Severe Thunderstorm Warning	PBZ	Guernsey, Muskingum, Noble	38 min
Jul 29, 4:14 PM EDT	Special Weather Statement	PBZ	Brooke, Ohio	46 min
Jul 29, 5:46 PM EDT	Special Weather Statement	PBZ	Marion, Monongalia, Wetzel	59 min
Jul 29, 6:50 PM EDT	Special Weather Statement	PBZ	Marion, Monongalia	25 min
Jul 29, 7:29 PM EDT	Special Weather Statement	PBZ	Tucker	46 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2011 Severe Thunderstorm Warnings in West Virginia, 2011 Every severe thunderstorm warning in 2011

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.