Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 806
The Storm Prediction Center issued this severe thunderstorm watch at Aug 25, 2011, 12:42 AM EDT for 4 states. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 25, 2011, 12:42 AM EDT (04:42 UTC)
- Expired
- Aug 25, 2011, 6:00 AM EDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 30 counties
Steuben County, NY, Carroll County, OH, Columbiana County, OH, Coshocton County, OH, Harrison County, OH, Jefferson County, OH, Tuscarawas County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Clarion County, PA, Clearfield County, PA, Elk County, PA, Forest County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, McKean County, PA, Mercer County, PA, Potter County, PA, Tioga County, PA, Venango County, PA, Warren County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV
The radar
The State College radar (KCCX), 128 km from the middle of the area, began a volume at 04:44 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
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 25, 12:54 AM EDT | Severe Thunderstorm Warning | CTP | Elk, McKean, Potter, Warren | 66 min |
| Aug 25, 1:30 AM EDT | Severe Thunderstorm Warning | PBZ | Carroll, Columbiana | 60 min |
| Aug 25, 3:16 AM EDT | Severe Thunderstorm Warning | CTP | Cameron, Centre, Clearfield, Clinton, Elk, Lycoming | 59 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 00:00Z, 4.7 hours before the alert went out and 139 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.
- Mixed-layer CAPE
- 1205 J/kg
- Mixed-layer CIN
- -258 J/kg
- Mixed-layer LCL
- 896 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 251 m²/s²
- 0-3 km storm-relative helicity
- 235 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 24, 9:18 PM EDT | Severe Thunderstorm Watch | SPC | Allegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston and 6 more | 6 hr |
| Aug 24, 11:48 PM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Chemung, Cortland, Genesee and 11 more | 87 min |
| Aug 25, 2:31 AM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Cayuga, Chautauqua, Chemung, Cortland and 13 more | 119 min |
| Aug 24, 9:56 PM EDT | Mesoscale Discussion | SPC | Allen, Ashland, Auglaize, Brown, Butler, Champaign and 40 more | 94 min |
| Aug 24, 10:27 PM EDT | Tornado Watch | SPC | Ashland, Ashtabula, Crawford, Cuyahoga, Erie, Geauga and 22 more | 5 hr |
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.