Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 672

July 22, 201111 counties in Ohio; 25 counties in Pennsylvania; 9 counties in West Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Jul 22, 2011, 5:37 PM EDT for 11 counties in Ohio; 25 counties in Pennsylvania; 9 counties in West Virginia. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Jul 22, 2011, 5:37 PM EDT (21:37 UTC)
Expired
Jul 22, 2011, 10:03 PM EDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 45 counties

Belmont County, OH, Carroll County, OH, Columbiana County, OH, Coshocton County, OH, Guernsey County, OH, Harrison County, OH, Jefferson County, OH, Monroe County, OH, Muskingum County, OH, Noble County, OH, Tuscarawas County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Bedford County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Elk County, PA, Fayette County, PA, Forest County, PA, Greene County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, Mercer County, PA, Somerset County, PA, Venango County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marion County, WV, Marshall County, WV, Monongalia County, WV, Ohio County, WV, Preston County, WV, Tucker County, WV, Wetzel County, WV

The radar

The Pittsburgh radar (KPBZ), 69 km from the middle of the area, began a volume at 21:40 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
5%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
10%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jul 22, 5:45 PM EDTSevere Thunderstorm WarningPBZButler, Lawrence, Mercer47 min
Jul 22, 5:48 PM EDTSevere Thunderstorm WarningPBZArmstrong, Butler, Clarion, Indiana, Westmoreland42 min
Jul 22, 6:00 PM EDTSevere Thunderstorm WarningPBZAllegheny45 min
Jul 22, 6:30 PM EDTSevere Thunderstorm WarningPBZBelmont30 min
Jul 22, 6:48 PM EDTSevere Thunderstorm WarningPBZFayette, Greene, Washington42 min
Jul 22, 7:04 PM EDTSevere Thunderstorm WarningPBZBelmont29 min
Jul 22, 7:32 PM EDTSevere Thunderstorm WarningCTPBedford34 min
Jul 22, 7:50 PM EDTSevere Thunderstorm WarningPBZFayette40 min
Jul 22, 8:19 PM EDTSevere Thunderstorm WarningPBZMonongalia, Preston56 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 9.6 hours before the alert went out and 69 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-pSkew-T log-p diagram, Pittsburgh, PA at 12:00Z on 2011-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3887 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Pittsburgh, PA at 12:00Z on 2011-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -61 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
3887 J/kg
Mixed-layer CIN
-34 J/kg
Mixed-layer LCL
868 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
-61 m²/s²
0-3 km storm-relative helicity
-29 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 22, 11:20 AM EDTMesoscale DiscussionSPCAllen, Auglaize, Champaign, Clark, Crawford, Darke and 33 more55 min
Jul 22, 12:50 PM EDTMesoscale DiscussionSPCAllen, Ashland, Auglaize, Champaign, Clark, Clinton and 43 more55 min
Jul 22, 1:14 PM EDTSevere Thunderstorm WatchSPCAllen, Ashland, Auglaize, Champaign, Clark, Clinton and 45 more7 hr
Jul 22, 3:17 PM EDTMesoscale DiscussionSPCBelmont, Carroll, Columbiana, Guernsey, Harrison, Jefferson and 4 more58 min
Jul 22, 4:32 PM EDTMesoscale DiscussionSPCAllen, Ashland, Auglaize, Champaign, Clark, Clinton and 41 more88 min
Jul 22, 5:19 PM EDTMesoscale DiscussionSPCBelmont, Carroll, Columbiana, Coshocton, Geauga, Guernsey and 11 more56 min
Jul 22, 5:59 PM EDTMesoscale DiscussionSPCGallia, Lawrence2 hr
Jul 22, 7:10 PM EDTMesoscale DiscussionSPCClark, Clinton, Coshocton, Delaware, Fairfield, Fayette and 14 more35 min

Nearby

Severe Thunderstorm Watches in Pennsylvania, 2011Severe Thunderstorm Watches in Ohio, 2011Severe Thunderstorm Watches in West Virginia, 2011Every severe thunderstorm watch 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.