Alert archive / Arkansas / Severe Thunderstorm Watches in 2011
Severe Thunderstorm Watch 854
The Storm Prediction Center issued this severe thunderstorm watch at Sep 18, 2011, 5:41 PM CDT for 25 counties in Arkansas; McCurtain County, Oklahoma; 18 counties in Texas. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 18, 2011, 5:41 PM CDT (22:41 UTC)
- Expired
- Sep 19, 2011, 12:24 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 44 counties
Boone County, AR, Clark County, AR, Columbia County, AR, Conway County, AR, Garland County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Johnson County, AR, Lafayette County, AR, Little River County, AR, Logan County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Newton County, AR, Perry County, AR, Pike County, AR, Polk County, AR, Pope County, AR, Saline County, AR, Scott County, AR, Sevier County, AR, Union County, AR, Yell County, AR, McCurtain County, OK, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Franklin County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Morris County, TX, Nacogdoches County, TX, Panola County, TX, Red River County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Wood County, TX
The radar
The Western Arkansas radar (KSRX), 109 km from the middle of the area, began a volume at 22:42 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
18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 18, 6:27 PM CDT | Severe Thunderstorm Warning | LZK | Logan, Scott | 48 min |
| Sep 18, 6:41 PM CDT | Severe Thunderstorm Warning | SHV | McCurtain | 64 min |
| Sep 18, 7:13 PM CDT | Severe Thunderstorm Warning | SHV | Red River | 47 min |
| Sep 18, 7:17 PM CDT | Severe Thunderstorm Warning | SHV | Sevier | 58 min |
| Sep 18, 7:58 PM CDT | Flash Flood Warning | LZK | Scott, Yell | 3 hr |
| Sep 18, 8:00 PM CDT | Severe Thunderstorm Warning | SHV | Little River | 60 min |
| Sep 18, 8:14 PM CDT | Severe Thunderstorm Warning | SHV | Little River, Sevier | 61 min |
| Sep 18, 8:26 PM CDT | Severe Thunderstorm Warning | LZK | Garland, Montgomery, Yell | 34 min |
| Sep 18, 8:28 PM CDT | Severe Thunderstorm Warning | SHV | Camp, Franklin, Morris, Titus | 62 min |
| Sep 18, 8:55 PM CDT | Severe Thunderstorm Warning | LZK | Garland, Montgomery, Perry, Yell | 35 min |
| Sep 18, 8:58 PM CDT | Flash Flood Warning | SHV | Sevier | 2 hr |
| Sep 18, 9:01 PM CDT | Severe Thunderstorm Warning | SHV | Hempstead, Little River, Miller, Sevier | 59 min |
| Sep 18, 9:09 PM CDT | Severe Thunderstorm Warning | SHV | Smith, Upshur, Wood | 66 min |
| Sep 18, 9:23 PM CDT | Severe Thunderstorm Warning | SHV | Camp, Cass, Franklin, Marion, Morris, Titus | 52 min |
| Sep 18, 9:48 PM CDT | Severe Thunderstorm Warning | SHV | Columbia, Hempstead, Lafayette, Little River, Miller, Nevada | 57 min |
| Sep 18, 10:03 PM CDT | Severe Thunderstorm Warning | SHV | Cass, Harrison, Marion | 57 min |
| Sep 18, 10:11 PM CDT | Severe Thunderstorm Warning | SHV | Camp, Gregg, Rusk, Smith, Upshur, Wood | 49 min |
| Sep 18, 10:46 PM CDT | Severe Thunderstorm Warning | SHV | Columbia, Lafayette | 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
Shreveport, LA (KSHV), launched 12:00Z, 10.7 hours before the alert went out and 212 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
- 1085 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 570 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 51 m²/s²
- 0-3 km storm-relative helicity
- 45 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 18, 2:45 PM CDT | Mesoscale Discussion | SPC | Benton, Crawford, Sebastian, Washington | 2 hr |
| Sep 18, 3:30 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Carroll, Crawford, Franklin, Madison, Sebastian and 1 more | 8 hr |
| Sep 18, 6:48 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Conway, Crawford, Garland, Howard and 11 more | 57 min |
| Sep 17, 10:17 PM CDT | Mesoscale Discussion | SPC | Atoka, Bryan, Carter, Cherokee, Cleveland, Coal and 28 more | 88 min |
| Sep 18, 3:59 PM CDT | Mesoscale Discussion | SPC | Love | 31 min |
| Sep 18, 4:06 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bosque, Brown, Callahan, Coke, Coleman and 51 more | 9 hr |
| Sep 18, 6:18 PM CDT | Mesoscale Discussion | SPC | Bandera, Bexar, Blanco, Comal, Edwards, Hays and 6 more | 57 min |
Nearby
Severe Thunderstorm Watches in Arkansas, 2011Severe Thunderstorm Watches in Texas, 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.