Alert archive / Texas / Severe Thunderstorm Watches in 2015

Severe Thunderstorm Watch 55

April 11, 20154 states

The Storm Prediction Center issued this severe thunderstorm watch at Apr 11, 2015, 2:43 PM MDT for 4 states. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Apr 11, 2015, 2:43 PM MDT (20:43 UTC)
Expired: Apr 11, 2015, 10:00 PM MDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 25 counties

Baca County, CO, Grant County, KS, Haskell County, KS, Morton County, KS, Seward County, KS, Stanton County, KS, Stevens County, KS, Cimarron County, OK, Texas County, OK, Armstrong County, TX, Carson County, TX, Collingsworth County, TX, Dallam County, TX, Deaf Smith County, TX, Donley County, TX, Gray County, TX, Hansford County, TX, Hartley County, TX, Hutchinson County, TX, Moore County, TX, Oldham County, TX, Potter County, TX, Randall County, TX, Sherman County, TX, Wheeler County, TX

The radar

The Amarillo radar (KAMA), 154 km from the middle of the area, began a volume at 20:43 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: 20%
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: 10%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 11, 4:00 PM MDT	Severe Thunderstorm Warning	AMA	Hartley, Moore, Oldham	60 min
Apr 11, 4:39 PM MDT	Severe Thunderstorm Warning	AMA	Carson, Hutchinson, Moore, Potter	66 min
Apr 11, 4:41 PM MDT	Severe Thunderstorm Warning	PUB	Baca	17 min
Apr 11, 4:51 PM MDT	Tornado Warning	AMA	Moore, Potter	39 min
Apr 11, 5:17 PM MDT	Tornado Warning	AMA	Carson, Hutchinson, Moore, Potter	27 min
Apr 11, 5:31 PM MDT	Tornado Warning	AMA	Carson, Potter	44 min
Apr 11, 5:51 PM MDT	Severe Thunderstorm Warning	DDC	Morton, Stanton	54 min
Apr 11, 6:17 PM MDT	Tornado Warning	AMA	Carson, Gray	43 min
Apr 11, 6:20 PM MDT	Tornado Warning	DDC	Morton, Stanton	40 min
Apr 11, 6:30 PM MDT	Severe Thunderstorm Warning	AMA	Carson, Gray, Hutchinson, Roberts	60 min
Apr 11, 6:51 PM MDT	Tornado Warning	DDC	Grant, Morton, Stanton, Stevens	39 min
Apr 11, 6:57 PM MDT	Severe Thunderstorm Warning	AMA	Carson, Gray, Hutchinson, Roberts	11 min
Apr 11, 7:07 PM MDT	Severe Thunderstorm Warning	AMA	Carson, Gray	23 min
Apr 11, 7:26 PM MDT	Severe Thunderstorm Warning	AMA	Collingsworth, Gray, Hemphill, Wheeler	64 min
Apr 11, 7:29 PM MDT	Severe Thunderstorm Warning	DDC	Grant, Haskell, Seward, Stevens	46 min
Apr 11, 7:45 PM MDT	Severe Thunderstorm Warning	DDC	Grant, Hamilton, Kearny, Stanton	23 min
Apr 11, 8:28 PM MDT	Severe Thunderstorm Warning	AMA	Collingsworth, Wheeler	32 min
Apr 11, 8:51 PM MDT	Severe Thunderstorm Warning	DDC	Finney, Grant, Haskell, Kearny	33 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, 8.7 hours before the alert went out and 154 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: 8 J/kg
Mixed-layer CIN: -416 J/kg
Mixed-layer LCL: 1063 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 173 m²/s²
0-3 km storm-relative helicity: 197 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 11, 2:11 PM MDT	Mesoscale Discussion	SPC	Baca	94 min
Apr 11, 5:31 PM MDT	Mesoscale Discussion	SPC	Grant, Hamilton, Haskell, Kearny, Meade, Morton and 3 more	89 min

Nearby

Severe Thunderstorm Watches in Texas, 2015 Severe Thunderstorm Watches in Kansas, 2015 Severe Thunderstorm Watches in Oklahoma, 2015 Every severe thunderstorm watch in 2015

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.