Alert archive / Oklahoma / Severe Thunderstorm Watches in 2018

Severe Thunderstorm Watch 443

December 26, 201815 counties in Oklahoma; 8 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Dec 26, 2018, 5:06 PM CST for 15 counties in Oklahoma; 8 counties in Texas. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Dec 26, 2018, 5:06 PM CST (23:06 UTC)
Expired: Dec 26, 2018, 8:42 PM CST
In force: 4 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1 in
Strongest gust expected: 60 kt

All 23 counties

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, Kiowa County, OK, Love County, OK, Murray County, OK, Stephens County, OK, Tillman County, OK, Archer County, TX, Baylor County, TX, Clay County, TX, Foard County, TX, Hardeman County, TX, Knox County, TX, Wichita County, TX, Wilbarger County, TX

The radar

The Altus AFB radar (KFDR), 22 km from the middle of the area, began a volume at 23:08 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 40%
One or more gusts of 65 knots or more: 20%
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 26, 5:40 PM CST	Severe Thunderstorm Warning	OUN	Beckham, Greer, Harmon, Jackson, Kiowa, Roger Mills and 2 more	50 min
Dec 26, 5:55 PM CST	Severe Thunderstorm Warning	OUN	Comanche, Cotton, Tillman	50 min
Dec 26, 6:23 PM CST	Severe Thunderstorm Warning	OUN	Beckham, Caddo, Comanche, Custer, Dewey, Greer and 5 more	52 min
Dec 26, 6:38 PM CST	Severe Thunderstorm Warning	OUN	Caddo, Comanche, Cotton, Grady, Jefferson, Stephens and 1 more	52 min
Dec 26, 7:25 PM CST	Severe Thunderstorm Warning	OUN	Caddo, Canadian, Carter, Garvin, Grady, Jefferson and 4 more	35 min
Dec 26, 7:55 PM CST	Severe Thunderstorm Warning	OUN	Canadian, Cleveland, Garvin, Grady, Lincoln, Logan and 6 more	50 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 12:00Z, 11.1 hours before the alert went out and 171 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: 29 J/kg
Mixed-layer CIN: -72 J/kg
Mixed-layer LCL: 509 m above ground
0-6 km bulk shear: 175 kt
0-1 km storm-relative helicity: 1665 m²/s²
0-3 km storm-relative helicity: 1650 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 26, 11:33 AM CST	Mesoscale Discussion	SPC	Bailey, Borden, Briscoe, Castro, Coke, Crockett and 24 more	117 min
Dec 26, 12:28 PM CST	Mesoscale Discussion	SPC	Archer, Baylor, Brown, Callahan, Coleman, Comanche and 22 more	2 hr
Dec 26, 12:44 PM CST	Severe Thunderstorm Watch	SPC	Armstrong, Borden, Briscoe, Carson, Castro, Childress and 40 more	6 hr
Dec 26, 2:11 PM CST	Tornado Watch	SPC	Bell, Bosque, Brown, Burnet, Callahan, Coleman and 29 more	10 hr
Dec 26, 3:21 PM CST	Mesoscale Discussion	SPC	Armstrong, Borden, Briscoe, Castro, Childress, Coke and 34 more	84 min
Dec 26, 4:43 PM CST	Mesoscale Discussion	SPC	Archer, Baylor, Bell, Blanco, Bosque, Brown and 42 more	2 hr
Dec 26, 4:58 PM CST	Mesoscale Discussion	SPC	Archer, Baylor, Bell, Blanco, Bosque, Brown and 42 more	62 min
Dec 26, 5:48 PM CST	Tornado Watch	SPC	Atascosa, Bandera, Bastrop, Bexar, Blanco, Caldwell and 17 more	8 hr

Nearby

Severe Thunderstorm Watches in Oklahoma, 2018 Severe Thunderstorm Watches in Texas, 2018 Every severe thunderstorm watch in 2018

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.