Alert archive / Texas / Severe Thunderstorm Watches in 2016

Severe Thunderstorm Watch 99

April 20, 20165 counties in Oklahoma; 29 counties in Texas

The Storm Prediction Center issued this severe thunderstorm watch at Apr 20, 2016, 8:17 PM CDT for 5 counties in Oklahoma; 29 counties in Texas. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Apr 20, 2016, 8:17 PM CDT (01:17 UTC)
Expired
Apr 21, 2016, 2:00 AM CDT
In force
6 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 34 counties

Beckham County, OK, Greer County, OK, Harmon County, OK, Jackson County, OK, Tillman County, OK, Armstrong County, TX, Baylor County, TX, Briscoe County, TX, Carson County, TX, Childress County, TX, Collingsworth County, TX, Cottle County, TX, Crosby County, TX, Dickens County, TX, Donley County, TX, Fisher County, TX, Floyd County, TX, Foard County, TX, Garza County, TX, Gray County, TX, Hale County, TX, Hall County, TX, Hardeman County, TX, Haskell County, TX, Jones County, TX, Kent County, TX, King County, TX, Knox County, TX, Lubbock County, TX, Motley County, TX, Stonewall County, TX, Throckmorton County, TX, Wheeler County, TX, Wilbarger County, TX

The radar

The Lubbock radar (KLBB), 139 km from the middle of the area, began a volume at 01:19 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
30%
One or more gusts of 65 knots or more
10%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 20, 8:40 PM CDTSevere Thunderstorm WarningAMACollingsworth, Donley50 min
Apr 20, 8:40 PM CDTSevere Thunderstorm WarningLUBBriscoe, Floyd, Hale, Swisher35 min
Apr 20, 8:41 PM CDTSevere Thunderstorm WarningAMACollingsworth, Donley7 min
Apr 20, 9:14 PM CDTSevere Thunderstorm WarningLUBCrosby, Floyd, Motley31 min
Apr 20, 9:45 PM CDTSevere Thunderstorm WarningLUBCrosby, Dickens, Floyd, Motley30 min
Apr 20, 10:14 PM CDTSevere Thunderstorm WarningLUBCrosby, Dickens, Floyd31 min
Apr 20, 10:55 PM CDTSevere Thunderstorm WarningLUBCrosby, Dickens, Garza, Kent35 min
Apr 20, 11:30 PM CDTSevere Thunderstorm WarningLUBDickens, Kent, King, Stonewall30 min
Apr 21, 12:20 AM CDTSevere Thunderstorm WarningLUBGarza, Kent25 min
Apr 21, 12:44 AM CDTSevere Thunderstorm WarningLUBKent31 min
Apr 21, 12:50 AM CDTSevere Thunderstorm WarningSJTHaskell, Jones40 min
Apr 21, 1:25 AM CDTSevere Thunderstorm WarningSJTFisher, Nolan65 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, 1.3 hours before the alert went out and 143 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 2016-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 487 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 2016-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 86 square meters per square second.1939587897Sfc1 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
487 J/kg
Mixed-layer CIN
-45 J/kg
Mixed-layer LCL
1746 m above ground
0-6 km bulk shear
65 kt
0-1 km storm-relative helicity
86 m²/s²
0-3 km storm-relative helicity
213 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.7

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 20, 8:22 PM CDTMesoscale DiscussionSPCDuval, Jim Hogg, Starr, Webb, Zapata83 min
Apr 20, 9:40 PM CDTMesoscale DiscussionSPCCottle, Crosby, Dickens, Fisher, Foard, Garza and 7 more65 min
Apr 20, 11:35 PM CDTMesoscale DiscussionSPCCrosby, Fisher, Garza, Haskell, Jones, Kent and 5 more55 min
Apr 21, 1:16 AM CDTMesoscale DiscussionSPCBorden, Callahan, Coke, Coleman, Dawson, Fisher and 19 more89 min
Apr 21, 1:44 AM CDTSevere Thunderstorm WatchSPCBorden, Coke, Dawson, Gaines, Glasscock, Howard and 7 more4 hr
Apr 21, 4:57 AM CDTMesoscale DiscussionSPCCoke, Coleman, Concho, Runnels, Taylor, Tom Green93 min
Apr 21, 9:40 AM CDTMesoscale DiscussionSPCBrazoria, Chambers, Hardin, Liberty, Tyler2 hr
Apr 21, 2:14 PM CDTMesoscale DiscussionSPCCameron, Hidalgo, Kenedy, Willacy2 hr
Apr 21, 2:36 PM CDTMesoscale DiscussionSPCBrewster, Crockett, Edwards, Pecos, Terrell, Val Verde2 hr

Nearby

Severe Thunderstorm Watches in Texas, 2016Severe Thunderstorm Watches in Oklahoma, 2016Every severe thunderstorm watch in 2016

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.