Alert archive / Arkansas / Tornado Watches in 2021
Tornado Watch 556
The Storm Prediction Center issued this tornado watch at Dec 10, 2021, 6:51 PM CST for 16 counties in Arkansas; 5 counties in Oklahoma. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 10, 2021, 6:51 PM CST (00:51 UTC)
- Expired
- Dec 10, 2021, 11:00 PM CST
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 65 kt
All 21 counties
Baxter County, AR, Benton County, AR, Boone County, AR, Carroll County, AR, Crawford County, AR, Franklin County, AR, Johnson County, AR, Logan County, AR, Madison County, AR, Marion County, AR, Newton County, AR, Polk County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Washington County, AR, Adair County, OK, Haskell County, OK, Latimer County, OK, LeFlore County, OK, Sequoyah County, OK
The radar
The Western Arkansas radar (KSRX), 97 km from the middle of the area, began a volume at 00:51 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
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
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 |
|---|---|---|---|---|
| Dec 10, 6:56 PM CST | Severe Thunderstorm Warning | TSA | Washington | 34 min |
| Dec 10, 7:22 PM CST | Tornado Warning | TSA | Washington | 22 min |
| Dec 10, 8:42 PM CST | Severe Thunderstorm Warning | TSA | Franklin, Sebastian | 33 min |
| Dec 10, 8:53 PM CST | Severe Thunderstorm Warning | LZK | Johnson, Logan, Scott | 52 min |
| Dec 10, 9:27 PM CST | Severe Thunderstorm Warning | LZK | Conway, Johnson, Logan, Pope, Van Buren, Yell | 48 min |
| Dec 10, 10:02 PM CST | Severe Thunderstorm Warning | LZK | Cleburne, Conway, Searcy, Stone, Van Buren | 25 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 00:00Z, 0.9 hours before the alert went out and 133 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
- 637 J/kg
- Mixed-layer CIN
- -23 J/kg
- Mixed-layer LCL
- 1113 m above ground
- 0-6 km bulk shear
- 80 kt
- 0-1 km storm-relative helicity
- 344 m²/s²
- 0-3 km storm-relative helicity
- 300 m²/s²
- Significant tornado parameter
- 1.2
- Supercell composite
- 8.4
The text
As transmitted.
257
WWUS20 KWNS 110049
SEL6
SPC WW 110049
ARZ000-OKZ000-110500-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 556
NWS Storm Prediction Center Norman OK
650 PM CST Fri Dec 10 2021
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Western Arkansas
Eastern Oklahoma
* Effective this Friday evening from 650 PM until 1100 PM CST.
* Primary threats include...
A couple tornadoes possible
Scattered damaging winds and isolated significant gusts to 75
mph possible
Isolated large hail events to 1.5 inches in diameter possible
SUMMARY...Linear clustering with embedded supercell structures
should rapidly spread east-northeast across western Arkansas this
evening.
The tornado watch area is approximately along and 50 statute miles
east and west of a line from 15 miles northeast of Harrison AR to 20
miles south of Poteau OK. For a complete depiction of the watch see
the associated watch outline update (WOUS64 KWNS WOU6).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 552...WW 553...WW
554...WW 555...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 24040.
...GramsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 10, 6:22 PM CST | Mesoscale Discussion | SPC | Craighead, Greene, Jackson, Mississippi, Poinsett | 53 min |
| Dec 10, 6:34 PM CST | Tornado Watch | SPC | Columbia, Hempstead, Howard, Lafayette, Little River, Miller and 2 more | 4 hr |
| Dec 10, 6:37 PM CST | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 10 more | 83 min |
| Dec 10, 7:34 PM CST | Mesoscale Discussion | SPC | Clark, Crittenden, Cross, Faulkner, Garland, Grant and 16 more | 86 min |
| Dec 10, 7:54 PM CST | Mesoscale Discussion | SPC | Boone, Carroll, Crawford, Franklin, Johnson, Logan and 7 more | 2 hr |
| Dec 10, 9:40 PM CST | Mesoscale Discussion | SPC | Arkansas, Clark, Cleveland, Craighead, Crittenden, Cross and 13 more | 2 hr |
| Dec 10, 10:00 PM CST | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Chicot, Columbia, Desha and 5 more | 90 min |
| Dec 10, 10:09 PM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 17 more | 96 min |
| Dec 10, 10:44 PM CST | Tornado Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 16 more | 6 hr |
| Dec 11, 2:00 AM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Desha and 4 more | 90 min |
Nearby
Tornado Watches in Arkansas, 2021Tornado Watches in Oklahoma, 2021Every tornado watch in 2021
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.