Alert archive / Oklahoma / Severe Thunderstorm Watches in 2021

Severe Thunderstorm Watch 320

June 25, 202117 counties in Oklahoma; 7 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Jun 25, 2021, 11:59 PM CDT for 17 counties in Oklahoma; 7 counties in Texas. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Jun 25, 2021, 11:59 PM CDT (04:59 UTC)
Expired
Jun 26, 2021, 5:00 AM CDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
65 kt
All 24 counties

Beckham County, OK, Blaine County, OK, Caddo County, OK, Canadian County, OK, Cleveland County, OK, Custer County, OK, Grady County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Kingfisher County, OK, Kiowa County, OK, Logan County, OK, McClain County, OK, Oklahoma County, OK, Roger Mills County, OK, Washita County, OK, Briscoe County, TX, Childress County, TX, Collingsworth County, TX, Donley County, TX, Hall County, TX, Hardeman County, TX, Wheeler County, TX

The radar

The Altus AFB radar (KFDR), 103 km from the middle of the area, began a volume at 05:00 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
40%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
60%

Warnings issued inside it

8 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jun 26, 12:26 AM CDTSevere Thunderstorm WarningAMACollingsworth, Donley, Wheeler64 min
Jun 26, 12:47 AM CDTSevere Thunderstorm WarningOUNBeckham, Greer, Harmon, Roger Mills43 min
Jun 26, 12:53 AM CDTSevere Thunderstorm WarningLUBBriscoe, Swisher67 min
Jun 26, 1:19 AM CDTSevere Thunderstorm WarningOUNBeckham, Custer, Greer, Kiowa, Washita41 min
Jun 26, 1:55 AM CDTSevere Thunderstorm WarningOUNBlaine, Caddo, Custer, Kiowa, Washita50 min
Jun 26, 2:40 AM CDTSevere Thunderstorm WarningOUNBlaine, Caddo, Canadian, Grady, Kingfisher50 min
Jun 26, 3:14 AM CDTSevere Thunderstorm WarningOUNCanadian, Kingfisher, Logan, Oklahoma46 min
Jun 26, 3:52 AM CDTSevere Thunderstorm WarningOUNCleveland, Lincoln, Logan, Oklahoma, Pottawatomie38 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

Amarillo Airport, TX (KAMA), launched 00:00Z, 5.0 hours before the alert went out and 189 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.

Skew-T log-pSkew-T log-p diagram, Amarillo Airport, TX at 00:00Z on 2021-06-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 957 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Amarillo Airport, TX at 00:00Z on 2021-06-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 295 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
957 J/kg
Mixed-layer CIN
-173 J/kg
Mixed-layer LCL
1729 m above ground
0-6 km bulk shear
46 kt
0-1 km storm-relative helicity
295 m²/s²
0-3 km storm-relative helicity
439 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.3

Open this sounding in Storm Lab

The text

As transmitted.

823 
WWUS20 KWNS 260455
SEL0  
SPC WW 260455
OKZ000-TXZ000-260800-

URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 320
NWS Storm Prediction Center Norman OK
1200 AM CDT Sat Jun 26 2021

The NWS Storm Prediction Center has issued a

* Severe Thunderstorm Watch for portions of 
  Southwest Oklahoma
  Southeast Texas Panhandle

* Effective this Saturday morning from Midnight until 300 AM CDT.

* Primary threats include...
  Scattered damaging winds and isolated significant gusts to 75
    mph possible
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A lingering convective cluster across the eastern TX
Panhandle should spread into parts of southwest Oklahoma with a
short-duration threat for damaging winds.

The severe thunderstorm watch area is approximately along and 65
statute miles east and west of a line from 30 miles north northwest
of Clinton OK to 20 miles southwest of Childress TX. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU0).

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.

&&

OTHER WATCH INFORMATION...This severe thunderstorm watch replaces
severe thunderstorm watch number 318. Watch number 318 will not
be in effect after midnight cdt. 

AVIATION...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 550. Mean storm motion vector
29030.

...Grams

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 25, 8:49 PM CDTMesoscale DiscussionSPCBeckham, Blaine, Custer, Dewey, Greer, Harmon and 3 more86 min
Jun 25, 11:36 PM CDTMesoscale DiscussionSPCEllis, Roger Mills84 min
Jun 25, 11:42 PM CDTMesoscale DiscussionSPCCraig, Nowata, Osage, Ottawa, Washington63 min
Jun 26, 1:53 AM CDTMesoscale DiscussionSPCBlaine, Caddo, Canadian, Comanche, Custer, Grady and 7 more67 min
Jun 26, 12:59 PM CDTMesoscale DiscussionSPCCaddo, Canadian, Cleveland, Comanche, Cotton, Garvin and 12 more2 hr
Jun 26, 3:27 PM CDTMesoscale DiscussionSPCHarmon2 hr
Jun 26, 3:48 PM CDTSevere Thunderstorm WatchSPCCaddo, Carter, Comanche, Cotton, Garvin, Grady and 10 more9 hr
Jun 26, 6:27 PM CDTMesoscale DiscussionSPCComanche, Cotton, Grady, Jackson, Jefferson, McClain and 2 more93 min
Jun 26, 4:58 PM CDTSevere Thunderstorm WatchSPCBailey, Briscoe, Castro, Deaf Smith, Hale, Hall and 6 more8 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.