Alert archive / Oklahoma / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 161

April 21, 200714 counties in Oklahoma; Foard County, Hardeman County, Texas

The Storm Prediction Center issued this severe thunderstorm watch at Apr 21, 2007, 11:02 PM CDT for 14 counties in Oklahoma; Foard County, Hardeman County, Texas. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Apr 21, 2007, 11:02 PM CDT (04:02 UTC)
Expired
Apr 22, 2007, 2:31 AM CDT
In force
3 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt

Counties 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, Washita County, OK, Woods County, OK, Woodward County, OK, Foard County, TX, Hardeman County, TX

The radar

The Altus AFB radar (KFDR), 169 km from the middle of the area, began a volume at 04:02 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
10%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
40%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
70%

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, 4.0 hours before the alert went out and 196 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 2007-04-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1794 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 2007-04-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 263 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
1794 J/kg
Mixed-layer CIN
-60 J/kg
Mixed-layer LCL
946 m above ground
0-6 km bulk shear
59 kt
0-1 km storm-relative helicity
263 m²/s²
0-3 km storm-relative helicity
301 m²/s²
Significant tornado parameter
3.3
Supercell composite
16.9

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 21, 7:41 PM CDTMesoscale DiscussionSPCBeaver, Cimarron, Texas2 hr
Apr 21, 10:45 PM CDTMesoscale DiscussionSPCAlfalfa, Beaver, Beckham, Blaine, Caddo, Comanche and 14 more60 min
Apr 22, 3:51 PM CDTMesoscale DiscussionSPCAtoka, Bryan, Carter, Coal, Creek, Garvin and 18 more2 hr

Nearby

Severe Thunderstorm Watches in Oklahoma, 2007Severe Thunderstorm Watches in Texas, 2007Every severe thunderstorm watch in 2007

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.