Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 164
The Storm Prediction Center issued this severe thunderstorm watch at Apr 20, 2011, 2:22 AM EDT for 11 counties in Ohio; 15 counties in Pennsylvania; 9 counties in West Virginia. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 20, 2011, 2:22 AM EDT (06:22 UTC)
- Expired
- Apr 20, 2011, 5:29 AM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 35 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, Butler County, PA, Clarion County, PA, Fayette County, PA, Forest County, PA, Greene County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, Mercer 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), 47 km from the middle of the area, began a volume at 06:23 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
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 5%
- 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
- 60%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 20, 2:43 AM EDT | Severe Thunderstorm Warning | PBZ | Carroll, Coshocton, Guernsey, Harrison, Muskingum, Noble and 1 more | 62 min |
| Apr 20, 2:58 AM EDT | Tornado Warning | PBZ | Coshocton, Muskingum, Tuscarawas | 47 min |
| Apr 20, 3:37 AM EDT | Severe Thunderstorm Warning | PBZ | Belmont, Carroll, Columbiana, Guernsey, Harrison, Jefferson and 1 more | 38 min |
| Apr 20, 4:11 AM EDT | Severe Thunderstorm Warning | PBZ | Columbiana | 34 min |
| Apr 20, 4:37 AM EDT | Severe Thunderstorm Warning | PBZ | Armstrong, Butler, Clarion | 38 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, 6.4 hours before the alert went out and 63 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
- 2 J/kg
- Mixed-layer CIN
- -392 J/kg
- Mixed-layer LCL
- 1017 m above ground
- 0-6 km bulk shear
- 68 kt
- 0-1 km storm-relative helicity
- 234 m²/s²
- 0-3 km storm-relative helicity
- 422 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.5
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 19, 9:37 PM EDT | Severe Thunderstorm Watch | SPC | Allen, Defiance, Fulton, Henry, Paulding, Putnam and 2 more | 3 hr |
| Apr 19, 9:47 PM EDT | Mesoscale Discussion | SPC | Brown, Butler, Champaign, Clark, Clermont, Clinton and 9 more | 88 min |
| Apr 19, 10:13 PM EDT | Tornado Watch | SPC | Adams, Auglaize, Brown, Butler, Champaign, Clark and 26 more | 6 hr |
| Apr 19, 11:47 PM EDT | Mesoscale Discussion | SPC | Ashland, Carroll, Crawford, Fulton, Hancock, Henry and 14 more | 58 min |
| Apr 20, 12:18 AM EDT | Severe Thunderstorm Watch | SPC | Ashland, Ashtabula, Crawford, Erie, Geauga, Hancock and 21 more | 4 hr |
| Apr 20, 12:56 AM EDT | Mesoscale Discussion | SPC | Adams, Brown, Butler, Clark, Clermont, Clinton and 17 more | 94 min |
| Apr 20, 1:59 AM EDT | Tornado Watch | SPC | Athens, Gallia, Jackson, Lawrence, Meigs, Morgan and 3 more | 5 hr |
| Apr 20, 3:20 AM EDT | Mesoscale Discussion | SPC | Athens, Belmont, Carroll, Columbiana, Gallia, Guernsey and 10 more | 85 min |
| Apr 20, 3:45 PM EDT | Mesoscale Discussion | SPC | Adams, Bedford, Berks, Blair, Bradford, Cambria and 30 more | 30 min |
| Apr 20, 4:03 PM EDT | Severe Thunderstorm Watch | SPC | Adams, Bedford, Berks, Blair, Bradford, Carbon and 29 more | 4 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.