Alert archive / Oklahoma / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 113, NWS Norman, OK

April 23, 2021Jefferson County, Stephens County, Oklahoma

NWS Norman, OK issued this severe thunderstorm warning at Apr 23, 2021, 8:36 PM CDT for Jefferson County, Stephens County, Oklahoma. It was in force for 39 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Apr 23, 2021, 8:36 PM CDT (01:36 UTC)
Expired: Apr 23, 2021, 9:15 PM CDT
In force: 39 min
Issued by: NWS Norman, OK
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Jefferson County, OK, Stephens County, OK

The radar

The Altus AFB radar (KFDR), 96 km from the middle of the area, began a volume at 01:40 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 23, 8:02 PM CDT	Severe Thunderstorm Watch	SPC	4 hr

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 1.6 hours before the alert went out and 117 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 486 J/kg
Mixed-layer CIN: -47 J/kg
Mixed-layer LCL: 504 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 345 m²/s²
0-3 km storm-relative helicity: 408 m²/s²
Significant tornado parameter: 1.2
Supercell composite: 6.8

Open this sounding in Storm Lab

The text

As transmitted.

570 
WUUS54 KOUN 240136
SVROUN
OKC067-137-240215-
/O.NEW.KOUN.SV.W.0113.210424T0136Z-210424T0215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Norman OK
836 PM CDT Fri Apr 23 2021

The National Weather Service in Norman has issued a

* Severe Thunderstorm Warning for...
  Northern Jefferson County in southern Oklahoma...
  Southern Stephens County in southern Oklahoma...

* Until 915 PM CDT.

* At 836 PM CDT, severe thunderstorms were located along a line
  extending from 3 miles southeast of Duncan to 4 miles south of
  Hastings, moving east at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Duncan, Waurika, Comanche, Hastings, Loco, Addington and Waurika
  Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3416 9814 3423 9814 3449 9798 3443 9756
      3413 9768
TIME...MOT...LOC 0136Z 256DEG 35KT 3450 9792 3415 9810 

HAIL...1.00IN
WIND...60MPH
 
$$

TL

The office that day

Everything else NWS Norman, OK issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 23, 7:06 PM CDT	Severe Thunderstorm Warning	OUN	Harmon, Jackson	39 min
Apr 23, 7:15 PM CDT	Special Weather Statement	OUN	Garfield	30 min
Apr 23, 7:24 PM CDT	Special Weather Statement	OUN	Comanche	36 min
Apr 23, 7:52 PM CDT	Severe Thunderstorm Warning	OUN	Cotton	37 min
Apr 23, 8:00 PM CDT	Special Weather Statement	OUN	Grady	30 min
Apr 23, 8:04 PM CDT	Special Weather Statement	OUN	Stephens	26 min
Apr 23, 8:18 PM CDT	Severe Thunderstorm Warning	OUN	Cotton, Jefferson	42 min
Apr 23, 8:24 PM CDT	Severe Thunderstorm Warning	OUN	Garvin, Grady, McClain, Stephens	51 min
Apr 23, 8:44 PM CDT	Severe Thunderstorm Warning	OUN	Jefferson	31 min
Apr 23, 8:53 PM CDT	Special Weather Statement	OUN	Cleveland, McClain	37 min
Apr 23, 8:59 PM CDT	Special Weather Statement	OUN	Garvin	31 min
Apr 23, 9:02 PM CDT	Severe Thunderstorm Warning	OUN	Jefferson	43 min
Apr 23, 9:12 PM CDT	Severe Thunderstorm Warning	OUN	Carter, Jefferson, Love, Murray, Stephens	48 min
Apr 23, 9:29 PM CDT	Special Weather Statement	OUN	Cleveland, Garvin, Pottawatomie	31 min
Apr 23, 10:00 PM CDT	Special Weather Statement	OUN	Carter, Murray, Pontotoc, Pottawatomie, Seminole	30 min
Apr 23, 10:29 PM CDT	Special Weather Statement	OUN	Coal, Hughes, Johnston, Love, Marshall, Pontotoc and 1 more	31 min
Apr 23, 11:00 PM CDT	Special Weather Statement	OUN	Atoka, Bryan, Coal, Hughes, Marshall, Seminole	30 min
Apr 23, 11:08 PM CDT	Areal Flood Advisory	OUN	Atoka, Bryan	3 hr

Nearby

Severe Thunderstorm Warnings in Oklahoma, 2021 Every severe thunderstorm warning 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.