Alert archive / Missouri / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 793
The Storm Prediction Center issued this severe thunderstorm watch at Aug 20, 2011, 6:04 PM CDT for 13 counties in Arkansas; 14 counties in Missouri. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2011, 6:04 PM CDT (23:04 UTC)
- Expired
- Aug 20, 2011, 10:44 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 27 counties
Baxter County, AR, Boone County, AR, Cleburne County, AR, Fulton County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Marion County, AR, Newton County, AR, Searcy County, AR, Sharp County, AR, Stone County, AR, Van Buren County, AR, Barry County, MO, Christian County, MO, Douglas County, MO, Greene County, MO, Howell County, MO, Lawrence County, MO, Oregon County, MO, Ozark County, MO, Shannon County, MO, Stone County, MO, Taney County, MO, Texas County, MO, Webster County, MO, Wright County, MO
The radar
The Springfield radar (KSGF), 99 km from the middle of the area, began a volume at 23:04 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
- 30%
- 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
- 70%
Warnings issued inside it
14 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 6:10 PM CDT | Severe Thunderstorm Warning | LZK | Newton, Searcy | 50 min |
| Aug 20, 6:14 PM CDT | Severe Thunderstorm Warning | LZK | Boone, Marion | 46 min |
| Aug 20, 6:30 PM CDT | Severe Thunderstorm Warning | SGF | Christian, Stone, Taney | 45 min |
| Aug 20, 6:40 PM CDT | Severe Thunderstorm Warning | LZK | Johnson, Newton | 36 min |
| Aug 20, 6:52 PM CDT | Severe Thunderstorm Warning | LZK | Newton, Searcy | 38 min |
| Aug 20, 7:05 PM CDT | Severe Thunderstorm Warning | LZK | Baxter, Fulton, Izard, Marion | 40 min |
| Aug 20, 7:11 PM CDT | Severe Thunderstorm Warning | SGF | Christian, Douglas, Ozark, Taney | 49 min |
| Aug 20, 7:16 PM CDT | Severe Thunderstorm Warning | LZK | Johnson, Newton, Pope, Searcy, Van Buren | 44 min |
| Aug 20, 7:31 PM CDT | Severe Thunderstorm Warning | LZK | Newton, Pope, Searcy, Van Buren | 44 min |
| Aug 20, 7:35 PM CDT | Flash Flood Warning | LZK | Newton | 3 hr |
| Aug 20, 7:39 PM CDT | Severe Thunderstorm Warning | LZK | Boone, Marion | 36 min |
| Aug 20, 8:23 PM CDT | Severe Thunderstorm Warning | SGF | Howell | 37 min |
| Aug 20, 8:24 PM CDT | Severe Thunderstorm Warning | LZK | Boone, Marion, Newton, Searcy | 24 min |
| Aug 20, 9:13 PM CDT | Severe Thunderstorm Warning | LZK | Fulton, Sharp | 18 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
Springfield, MO (KSGF), launched 12:00Z, 11.1 hours before the alert went out and 117 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
- 3504 J/kg
- Mixed-layer CIN
- -32 J/kg
- Mixed-layer LCL
- 518 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- 90 m²/s²
- 0-3 km storm-relative helicity
- 142 m²/s²
- Significant tornado parameter
- 2.2
- Supercell composite
- 14.7
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 20, 3:56 PM CDT | Mesoscale Discussion | SPC | Benton, Boone, Calhoun, Carroll, Clark, Columbia and 29 more | 64 min |
| Aug 19, 11:51 PM CDT | Mesoscale Discussion | SPC | Buchanan, Cass, Clay, Jackson, Platte | 54 min |
| Aug 20, 2:28 AM CDT | Mesoscale Discussion | SPC | Bates, Benton, Camden, Cass, Clay, Dallas and 10 more | 62 min |
Nearby
Severe Thunderstorm Watches in Missouri, 2011Severe Thunderstorm Watches in Arkansas, 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.