Alert archive / Texas / Mesoscale Discussions in 2007

Mesoscale Discussion 1820

August 20, 2007Texas County, Oklahoma; 18 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2007, 4:58 PM CDT for Texas County, Oklahoma; 18 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 20, 2007, 4:58 PM CDT (21:58 UTC)
Expired: Aug 20, 2007, 7:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Texas County, OK, Armstrong County, TX, Carson County, TX, Deaf Smith County, TX, Donley County, TX, Gray County, TX, Hansford County, TX, Hartley County, TX, Hemphill County, TX, Hutchinson County, TX, Lipscomb County, TX, Moore County, TX, Ochiltree County, TX, Oldham County, TX, Potter County, TX, Randall County, TX, Roberts County, TX, Sherman County, TX, Swisher County, TX

The radar

The Amarillo radar (KAMA), 66 km from the middle of the area, began a volume at 22:00 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.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 624Aug 20, 5:50 PM CDT

The nearest sounding before it

Dodge City, (KDDC), launched 12:00Z, 10.0 hours before the alert went out and 260 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: 3207 J/kg
Mixed-layer CIN: -106 J/kg
Mixed-layer LCL: 1415 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 51 m²/s²
0-3 km storm-relative helicity: 73 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 20, 5:52 PM CDT	Severe Thunderstorm Watch	SPC	Beaver, Ellis, Harper, Texas	6 hr

Nearby

Mesoscale Discussions in Texas, 2007 Mesoscale Discussions in Oklahoma, 2007 Every mesoscale discussion 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.