Alert archive / Texas / Mesoscale Discussions in 2012

Mesoscale Discussion 1786

August 18, 2012Cotton County, Jackson County, Tillman County, Oklahoma; 11 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2012, 1:10 PM CDT for Cotton County, Jackson County, Tillman County, Oklahoma; 11 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 18, 2012, 1:10 PM CDT (18:10 UTC)
Expired: Aug 18, 2012, 3:15 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Cotton County, OK, Jackson County, OK, Tillman County, OK, Archer County, TX, Baylor County, TX, Clay County, TX, Cottle County, TX, Foard County, TX, Hardeman County, TX, King County, TX, Knox County, TX, Throckmorton County, TX, Wichita County, TX, Wilbarger County, TX

The radar

The Altus AFB radar (KFDR), 53 km from the middle of the area, began a volume at 18:11 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 584Aug 18, 2:10 PM CDT

The nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 6.2 hours before the alert went out and 226 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: 884 J/kg
Mixed-layer CIN: -162 J/kg
Mixed-layer LCL: 892 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 183 m²/s²
0-3 km storm-relative helicity: 395 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 13.2

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 18, 3:52 AM CDT	Mesoscale Discussion	SPC	Alfalfa, Beaver, Ellis, Harper, Woods, Woodward	113 min
Aug 18, 9:29 AM CDT	Mesoscale Discussion	SPC	Alfalfa, Blaine, Canadian, Custer, Dewey, Garfield and 5 more	91 min
Aug 18, 2:05 PM CDT	Severe Thunderstorm Watch	SPC	Cotton, Jefferson, Tillman	7 hr
Aug 18, 5:00 PM CDT	Mesoscale Discussion	SPC	Cotton, Jefferson, Tillman	90 min
Aug 17, 7:53 PM CDT	Mesoscale Discussion	SPC	Bowie	2 hr
Aug 18, 6:29 AM CDT	Mesoscale Discussion	SPC	Bowie	2 hr

Nearby

Mesoscale Discussions in Texas, 2012 Mesoscale Discussions in Oklahoma, 2012 Every mesoscale discussion in 2012

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.