Alert archive / Virginia / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 99
The Storm Prediction Center issued this severe thunderstorm watch at Apr 5, 2011, 12:36 AM EDT for 7 counties in North Carolina; 27 counties in Virginia. It was in force for 111 min.
The area
The outline as issued.
The facts
- Issued
- Apr 5, 2011, 12:36 AM EDT (04:36 UTC)
- Expired
- Apr 5, 2011, 2:27 AM EDT
- In force
- 111 min
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 34 counties
Alleghany County, NC, Caswell County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Wilkes County, NC, Yadkin County, NC, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, City of Danville, VA, City of Galax, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Halifax County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Wythe County, VA
The radar
The Roanoke radar (KFCX), 15 km from the middle of the area, began a volume at 04:38 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
- 40%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
6 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 5, 12:45 AM EDT | Severe Thunderstorm Warning | RNK | Stokes, Surry, Wilkes, Yadkin | 75 min |
| Apr 5, 1:33 AM EDT | Severe Thunderstorm Warning | RNK | Alleghany, Bedford, Botetourt, Craig, Floyd, Franklin and 7 more | 57 min |
| Apr 5, 1:46 AM EDT | Severe Thunderstorm Warning | RNK | Bedford, Franklin, Henry, Patrick, Pittsylvania, City of Martinsville | 59 min |
| Apr 5, 1:58 AM EDT | Tornado Warning | RNK | Franklin, Henry, City of Martinsville | 17 min |
| Apr 5, 2:06 AM EDT | Severe Thunderstorm Warning | RNK | Caswell, Rockingham, Stokes | 54 min |
| Apr 5, 2:26 AM EDT | Severe Thunderstorm Warning | RNK | Amherst, Appomattox, Bedford, Buckingham, Campbell, Charlotte and 4 more | 57 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
Roanoke, VA (KRNK), launched 00:00Z, 4.6 hours before the alert went out and 59 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2731 m above ground
- 0-6 km bulk shear
- 58 kt
- 0-1 km storm-relative helicity
- 258 m²/s²
- 0-3 km storm-relative helicity
- 349 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 4, 9:32 PM EDT | Mesoscale Discussion | SPC | Alexander, Buncombe, Burke, Catawba, Cleveland, Gaston and 8 more | 58 min |
| Apr 4, 9:45 PM EDT | Severe Thunderstorm Watch | SPC | Alexander, Avery, Buncombe, Burke, Cabarrus, Caldwell and 22 more | 5 hr |
| Apr 5, 12:21 AM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Chatham, Cumberland, Harnett, Hoke and 7 more | 84 min |
| Apr 5, 12:48 AM EDT | Tornado Watch | SPC | Alamance, Anson, Bladen, Chatham, Cumberland, Davidson and 27 more | 5 hr |
| Apr 5, 2:13 AM EDT | Mesoscale Discussion | SPC | Forsyth, Rockingham, Stokes, Surry, Yadkin | 32 min |
| Apr 5, 2:18 AM EDT | Tornado Watch | SPC | Bertie, Camden, Caswell, Chowan, Currituck, Gates and 5 more | 8 hr |
| Apr 5, 2:24 AM EDT | Mesoscale Discussion | SPC | Cabarrus, Mecklenburg, Rowan | 66 min |
| Apr 5, 3:34 AM EDT | Mesoscale Discussion | SPC | Alamance, Beaufort, Bertie, Bladen, Brunswick, Camden and 49 more | 116 min |
| Apr 5, 4:00 AM EDT | Tornado Watch | SPC | Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 15 more | 6 hr |
| Apr 5, 7:08 AM EDT | Mesoscale Discussion | SPC | Beaufort, Brunswick, Carteret, Craven, Currituck, Dare and 10 more | 2 hr |
| Apr 5, 10:15 AM EDT | Mesoscale Discussion | SPC | Beaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 26 more | 90 min |
Nearby
Severe Thunderstorm Watches in Virginia, 2011Severe Thunderstorm Watches in North Carolina, 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.