Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 91, NWS Pittsburgh, PA

July 21, 2009Allegheny County, Beaver County, Butler County, Pennsylvania

NWS Pittsburgh, PA issued this severe thunderstorm warning at Jul 21, 2009, 4:27 PM EDT for Allegheny County, Beaver County, Butler County, Pennsylvania. It was in force for 63 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 21, 2009, 4:27 PM EDT (20:27 UTC)
Expired: Jul 21, 2009, 5:30 PM EDT
In force: 63 min
Issued by: NWS Pittsburgh, PA
Area: Storm-based polygon

Counties Allegheny County, PA, Beaver County, PA, Butler County, PA

The radar

The Pittsburgh radar (KPBZ), 21 km from the middle of the area, began a volume at 20:26 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, 8.5 hours before the alert went out and 31 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: 372 J/kg
Mixed-layer CIN: -28 J/kg
Mixed-layer LCL: 721 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 63 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 21, 4:09 PM EDT, 18 minutes earlier.

Area forecast discussion, Jul 21, 4:09 PM EDT, 18 minutes before

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Hazardous weather outlook, Jul 21, 9:48 AM EDT, 6 hours 39 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PITTSBURGH PA
948 AM EDT TUE JUL 21 2009

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-
029>032-WVZ001>004-012-021>023-041-221400-
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-
948 AM EDT TUE JUL 21 2009

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...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

In the hours before

Local storm report, Jul 21, 3:31 PM EDT, 56 minutes before

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Special weather statement, Jul 21, 3:35 PM EDT, 52 minutes before

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Local storm report, Jul 21, 3:42 PM EDT, 45 minutes before

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Special weather statement, Jul 21, 4:02 PM EDT, 25 minutes before

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Special weather statement, Jul 21, 4:06 PM EDT, 21 minutes before

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Local storm report, Jul 21, 4:21 PM EDT, 6 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 21, 1:44 PM EDT	Severe Thunderstorm Warning	PBZ	Washington	61 min
Jul 21, 2:16 PM EDT	Severe Thunderstorm Warning	PBZ	Beaver, Washington	59 min
Jul 21, 2:55 PM EDT	Severe Thunderstorm Warning	PBZ	Beaver, Lawrence	65 min
Jul 21, 2:59 PM EDT	Severe Thunderstorm Warning	PBZ	Allegheny	61 min
Jul 21, 3:16 PM EDT	Severe Thunderstorm Warning	PBZ	Allegheny, Butler	59 min
Jul 21, 4:34 PM EDT	Severe Thunderstorm Warning	PBZ	Butler, Lawrence, Mercer	56 min
Jul 21, 5:31 PM EDT	Severe Thunderstorm Warning	PBZ	Fayette	44 min
Jul 21, 7:16 PM EDT	Severe Thunderstorm Warning	PBZ	Venango	29 min
Jul 21, 12:50 PM EDT	Severe Thunderstorm Warning	PBZ	Jefferson	55 min
Jul 21, 2:11 PM EDT	Severe Thunderstorm Warning	PBZ	Carroll, Columbiana, Jefferson	64 min
Jul 21, 3:26 PM EDT	Severe Thunderstorm Warning	PBZ	Guernsey	25 min
Jul 21, 2:22 PM EDT	Severe Thunderstorm Warning	PBZ	Tucker	38 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2009 Every severe thunderstorm warning in 2009

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.