Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 202

April 25, 201118 counties in Ohio; 39 counties in Pennsylvania; 4 counties in West Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Apr 25, 2011, 2:47 PM EDT for 18 counties in Ohio; 39 counties in Pennsylvania; 4 counties in West Virginia. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Apr 25, 2011, 2:47 PM EDT (18:47 UTC)
Expired
Apr 25, 2011, 10:00 PM EDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 61 counties

Belmont County, OH, Carroll County, OH, Columbiana County, OH, Coshocton County, OH, Guernsey County, OH, Harrison County, OH, Holmes County, OH, Jefferson County, OH, Mahoning County, OH, Monroe County, OH, Muskingum County, OH, Noble County, OH, Portage County, OH, Stark County, OH, Summit County, OH, Trumbull County, OH, Tuscarawas County, OH, Wayne 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, Columbia County, PA, Crawford County, PA, Elk County, PA, Fayette County, PA, Forest County, PA, Greene County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lawrence County, PA, Lycoming County, PA, McKean County, PA, Mercer County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Potter County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Tioga County, PA, Union County, PA, Venango County, PA, Warren County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marshall County, WV, Ohio County, WV

The radar

The Pittsburgh radar (KPBZ), 47 km from the middle of the area, began a volume at 18:48 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
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
50%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 25, 2:59 PM EDTSevere Thunderstorm WarningPBZJefferson30 min
Apr 25, 3:14 PM EDTSevere Thunderstorm WarningCTPCameron, Clearfield, Elk61 min
Apr 25, 3:59 PM EDTSevere Thunderstorm WarningPBZCoshocton, Guernsey, Muskingum31 min
Apr 25, 4:09 PM EDTSevere Thunderstorm WarningCTPCameron, Clinton, Lycoming, Potter66 min
Apr 25, 4:22 PM EDTSevere Thunderstorm WarningPBZCoshocton, Tuscarawas38 min
Apr 25, 4:38 PM EDTSevere Thunderstorm WarningPBZGuernsey, Muskingum, Noble37 min
Apr 25, 4:44 PM EDTSevere Thunderstorm WarningPBZCarroll, Columbiana, Harrison, Jefferson46 min
Apr 25, 4:54 PM EDTSevere Thunderstorm WarningPBZColumbiana36 min
Apr 25, 5:16 PM EDTSevere Thunderstorm WarningPBZBelmont, Guernsey, Harrison, Noble44 min
Apr 25, 5:23 PM EDTSevere Thunderstorm WarningPBZForest37 min
Apr 25, 5:32 PM EDTSevere Thunderstorm WarningCTPMcKean, Warren58 min
Apr 25, 5:46 PM EDTSevere Thunderstorm WarningPBZCarroll, Columbiana, Guernsey, Harrison, Jefferson, Tuscarawas29 min
Apr 25, 5:50 PM EDTTornado WarningPBZForest25 min
Apr 25, 6:28 PM EDTSevere Thunderstorm WarningCTPMcKean32 min
Apr 25, 7:00 PM EDTSevere Thunderstorm WarningCTPMcKean, Potter30 min
Apr 25, 7:34 PM EDTSevere Thunderstorm WarningCTPElk, McKean, Potter26 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, 6.8 hours before the alert went out and 55 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 2011-04-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4 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 2011-04-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 66 square meters per square second.19395878Sfc1 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
4 J/kg
Mixed-layer CIN
-53 J/kg
Mixed-layer LCL
698 m above ground
0-6 km bulk shear
42 kt
0-1 km storm-relative helicity
66 m²/s²
0-3 km storm-relative helicity
87 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
Apr 25, 6:00 PM EDTMesoscale DiscussionSPCChemung60 min
Apr 25, 1:52 PM EDTMesoscale DiscussionSPCAshland, Belmont, Carroll, Columbiana, Coshocton, Cuyahoga and 21 more83 min
Apr 24, 9:02 PM EDTMesoscale DiscussionSPCBarbour, Braxton, Grant, Hampshire, Hardy, Jefferson and 7 more58 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.