Alert archive / Texas / Severe Thunderstorm Watches in 2018

Severe Thunderstorm Watch 104

May 18, 201817 counties in Oklahoma; 21 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at May 18, 2018, 3:35 PM CDT for 17 counties in Oklahoma; 21 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
May 18, 2018, 3:35 PM CDT (20:35 UTC)
Expired
May 18, 2018, 10:00 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 38 counties

Alfalfa County, OK, Beaver County, OK, Beckham County, OK, Custer County, OK, Dewey County, OK, Ellis County, OK, Greer County, OK, Harmon County, OK, Harper County, OK, Jackson County, OK, Kiowa County, OK, Major County, OK, Roger Mills County, OK, Tillman County, OK, Washita County, OK, Woods County, OK, Woodward County, OK, Armstrong County, TX, Briscoe County, TX, Carson County, TX, Childress County, TX, Collingsworth County, TX, Cottle County, TX, Donley County, TX, Floyd County, TX, Foard County, TX, Gray County, TX, Hall County, TX, Hansford County, TX, Hardeman County, TX, Hemphill County, TX, Hutchinson County, TX, Lipscomb County, TX, Motley County, TX, Ochiltree County, TX, Roberts County, TX, Wheeler County, TX, Wilbarger County, TX

The radar

The Vance AFB radar (KVNX), 172 km from the middle of the area, began a volume at 20:36 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
60%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
60%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
90%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 18, 4:58 PM CDTSevere Thunderstorm WarningAMAGray, Roberts62 min
May 18, 5:05 PM CDTSevere Thunderstorm WarningAMABeaver55 min
May 18, 5:21 PM CDTSevere Thunderstorm WarningLUBCrosby, Floyd39 min
May 18, 5:41 PM CDTTornado WarningAMALipscomb, Ochiltree34 min
May 18, 5:52 PM CDTSevere Thunderstorm WarningLUBBriscoe, Hall23 min
May 18, 5:57 PM CDTSevere Thunderstorm WarningAMALipscomb, Ochiltree, Roberts63 min
May 18, 5:58 PM CDTSevere Thunderstorm WarningAMABeaver47 min
May 18, 6:12 PM CDTSevere Thunderstorm WarningAMABeaver48 min
May 18, 6:26 PM CDTSevere Thunderstorm WarningOUNJackson49 min
May 18, 6:37 PM CDTSevere Thunderstorm WarningAMABeaver38 min
May 18, 6:55 PM CDTSevere Thunderstorm WarningOUNHarper50 min
May 18, 6:58 PM CDTSevere Thunderstorm WarningAMAHemphill, Lipscomb, Ochiltree, Roberts48 min
May 18, 7:49 PM CDTSevere Thunderstorm WarningOUNHarper41 min
May 18, 8:06 PM CDTSevere Thunderstorm WarningAMACollingsworth, Wheeler31 min
May 18, 8:10 PM CDTSevere Thunderstorm WarningOUNWoods, Woodward65 min
May 18, 8:41 PM CDTSevere Thunderstorm WarningOUNBeckham, Greer, Harmon49 min
May 18, 9:15 PM CDTSevere Thunderstorm WarningOUNAlfalfa, Woods45 min
May 18, 9:19 PM CDTSevere Thunderstorm WarningOUNBeckham, Greer, Jackson, Kiowa, Washita41 min
May 18, 9:59 PM CDTSevere Thunderstorm WarningOUNKiowa, Washita46 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 12:00Z, 8.6 hours before the alert went out and 194 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 12:00Z on 2018-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 664 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 12:00Z on 2018-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 403 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
664 J/kg
Mixed-layer CIN
-432 J/kg
Mixed-layer LCL
1504 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
403 m²/s²
0-3 km storm-relative helicity
528 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 18, 2:43 PM CDTMesoscale DiscussionSPCBeaver, Beckham, Dewey, Ellis, Greer, Harmon and 5 more2 hr

Nearby

Severe Thunderstorm Watches in Texas, 2018Severe Thunderstorm Watches in Oklahoma, 2018Every 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.