Alert archive / Oklahoma / Severe Thunderstorm Watches in 2020
Severe Thunderstorm Watch 474
The Storm Prediction Center issued this severe thunderstorm watch at Aug 29, 2020, 10:08 PM CDT for 20 counties in Oklahoma; 7 counties in Texas. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 29, 2020, 10:08 PM CDT (03:08 UTC)
- Expired
- Aug 30, 2020, 5:00 AM CDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 65 kt
All 27 counties
Beckham County, OK, Caddo County, OK, Carter County, OK, Comanche County, OK, Cotton County, OK, Garvin County, OK, Grady County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Jefferson County, OK, Johnston County, OK, Kiowa County, OK, Love County, OK, Marshall County, OK, Murray County, OK, Pontotoc County, OK, Stephens County, OK, Tillman County, OK, Washita County, OK, Archer County, TX, Baylor County, TX, Clay County, TX, Foard County, TX, Hardeman County, TX, Wichita County, TX, Wilbarger County, TX
The radar
The Altus AFB radar (KFDR), 44 km from the middle of the area, began a volume at 03:08 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
- 5%
- Ten or more severe wind reports
- 40%
- 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
- 80%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 30, 12:08 AM CDT | Severe Thunderstorm Warning | OUN | Jackson | 52 min |
| Aug 30, 1:52 AM CDT | Severe Thunderstorm Warning | OUN | Cotton, Tillman | 38 min |
| Aug 30, 2:03 AM CDT | Severe Thunderstorm Warning | OUN | Comanche, Cotton | 42 min |
| Aug 30, 2:28 AM CDT | Severe Thunderstorm Warning | OUN | Comanche, Cotton, Grady, Jefferson, Stephens | 47 min |
| Aug 30, 3:43 AM CDT | Severe Thunderstorm Warning | OUN | Carter, Johnston, Love, Marshall | 47 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
Norman, OK (KOUN), launched 00:00Z, 3.1 hours before the alert went out and 165 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
- 2451 J/kg
- Mixed-layer CIN
- -114 J/kg
- Mixed-layer LCL
- 1167 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 14 m²/s²
- 0-3 km storm-relative helicity
- 99 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 29, 9:39 PM CDT | Mesoscale Discussion | SPC | Comanche, Cotton, Greer, Harmon, Jackson, Jefferson and 3 more | 2 hr |
| Aug 29, 11:33 PM CDT | Mesoscale Discussion | SPC | Bryan, Choctaw, McCurtain | 87 min |
| Aug 30, 1:52 AM CDT | Mesoscale Discussion | SPC | Jefferson, Love | 53 min |
| Aug 29, 8:34 PM CDT | Severe Thunderstorm Watch | SPC | Briscoe, Childress, Collingsworth, Cottle, Donley, Floyd and 5 more | 4 hr |
| Aug 29, 8:38 PM CDT | Mesoscale Discussion | SPC | Armstrong, Carson, Childress, Collingsworth, Donley, Gray and 1 more | 67 min |
Nearby
Severe Thunderstorm Watches in Oklahoma, 2020Severe Thunderstorm Watches in Texas, 2020Every severe thunderstorm watch in 2020
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.