Alert archive / Arkansas / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 536
The Storm Prediction Center issued this severe thunderstorm watch at Jun 21, 2011, 6:43 PM CDT for 16 counties in Arkansas; 4 counties in Oklahoma. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2011, 6:43 PM CDT (23:43 UTC)
- Expired
- Jun 22, 2011, 1:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
Counties Conway County, AR, Garland County, AR, Howard County, AR, Johnson County, AR, Little River County, AR, Logan County, AR, Montgomery County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pope County, AR, Scott County, AR, Sebastian County, AR, Sevier County, AR, Van Buren County, AR, Yell County, AR, Choctaw County, OK, LeFlore County, OK, McCurtain County, OK, Pushmataha County, OK
The radar
The Western Arkansas radar (KSRX), 48 km from the middle of the area, began a volume at 23:47 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
- 50%
- 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 |
|---|---|---|---|---|
| Jun 21, 6:48 PM CDT | Severe Thunderstorm Warning | LZK | Scott | 42 min |
| Jun 21, 7:29 PM CDT | Severe Thunderstorm Warning | LZK | Scott | 46 min |
| Jun 21, 7:31 PM CDT | Flash Flood Warning | LZK | Scott | 3 hr |
| Jun 21, 8:26 PM CDT | Severe Thunderstorm Warning | LZK | Polk, Scott | 49 min |
| Jun 21, 8:48 PM CDT | Severe Thunderstorm Warning | LZK | Montgomery, Polk, Scott | 42 min |
| Jun 21, 10:27 PM CDT | Flash Flood Warning | LZK | Scott | 3 hr |
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, 11.7 hours before the alert went out and 229 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
- 1375 J/kg
- Mixed-layer CIN
- -85 J/kg
- Mixed-layer LCL
- 526 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 378 m²/s²
- 0-3 km storm-relative helicity
- 378 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 12.4
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 20, 9:46 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more | 9 hr |
| Jun 21, 3:15 AM CDT | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Crawford, Franklin, Madison and 2 more | 60 min |
| Jun 21, 6:21 PM CDT | Mesoscale Discussion | SPC | Franklin, Howard, Johnson, Logan, Montgomery, Perry and 6 more | 54 min |
| Jun 20, 7:56 PM CDT | Mesoscale Discussion | SPC | Carter, Cleveland, Cotton, Creek, Garvin, Grady and 17 more | 94 min |
Nearby
Severe Thunderstorm Watches in Arkansas, 2011Severe Thunderstorm Watches in Oklahoma, 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.