Alert archive / Oklahoma / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 383
The Storm Prediction Center issued this severe thunderstorm watch at Jul 18, 2021, 5:08 PM CDT for 15 counties in Oklahoma; 12 counties in Texas. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 18, 2021, 5:08 PM CDT (22:08 UTC)
- Expired
- Jul 18, 2021, 11:00 PM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 27 counties
Beckham County, OK, Blaine County, OK, Caddo County, OK, Comanche County, OK, Custer County, OK, Dewey County, OK, Ellis County, OK, Greer County, OK, Harmon County, OK, Kiowa County, OK, Major County, OK, Roger Mills County, OK, Texas County, OK, Washita County, OK, Woodward County, OK, Armstrong County, TX, Carson County, TX, Collingsworth County, TX, Donley County, TX, Gray County, TX, Hansford County, TX, Hemphill County, TX, Hutchinson County, TX, Lipscomb County, TX, Ochiltree County, TX, Roberts County, TX, Wheeler County, TX
The radar
The Vance AFB radar (KVNX), 171 km from the middle of the area, began a volume at 22:10 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
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- 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
- 10%
- Six or more combined severe hail and wind reports
- 70%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Amarillo Airport, TX (KAMA), launched 12:00Z, 10.1 hours before the alert went out and 193 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
- 1725 m above ground
- 0-6 km bulk shear
- 2 kt
- 0-1 km storm-relative helicity
- -34 m²/s²
- 0-3 km storm-relative helicity
- 14 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
245 WWUS20 KWNS 182206 SEL3 SPC WW 182206 OKZ000-TXZ000-190400- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 383 NWS Storm Prediction Center Norman OK 510 PM CDT Sun Jul 18 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Oklahoma Texas Panhandle * Effective this Sunday afternoon and evening from 510 PM until 1100 PM CDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Clusters of storms will continue to develop south-southeastward through the evening across western Oklahoma and the Texas Panhandle. Severe-caliber wind gusts can be expected along with isolated large hail. The severe thunderstorm watch area is approximately along and 95 statute miles east and west of a line from 95 miles northeast of Borger TX to 55 miles southwest of Clinton OK. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for 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. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 32020. ...Guyer
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 18, 2:32 PM CDT | Mesoscale Discussion | SPC | Alfalfa, Beaver, Ellis, Harper, Major, Texas and 2 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Oklahoma, 2021Severe Thunderstorm Watches in Texas, 2021Every severe thunderstorm 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.