Alert archive / Texas / Mesoscale Discussions in 2017

Mesoscale Discussion 1730

October 21, 201720 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Oct 21, 2017, 10:09 PM CDT for 20 counties in Texas. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued: Oct 21, 2017, 10:09 PM CDT (03:09 UTC)
Expired: Oct 21, 2017, 11:45 PM CDT
In force: 96 min
Issued by: the Storm Prediction Center

Counties Callahan County, TX, Collin County, TX, Cooke County, TX, Dallas County, TX, Denton County, TX, Eastland County, TX, Fannin County, TX, Grayson County, TX, Hood County, TX, Hunt County, TX, Jack County, TX, Montague County, TX, Palo Pinto County, TX, Parker County, TX, Rockwall County, TX, Shackelford County, TX, Stephens County, TX, Tarrant County, TX, Wise County, TX, Young County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 74 km from the middle of the area, began a volume at 03:08 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 nearest sounding before it

Fort Worth, TX (KFWD), launched 00:00Z, 3.2 hours before the alert went out and 51 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: 1142 J/kg
Mixed-layer CIN: -102 J/kg
Mixed-layer LCL: 1889 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 124 m²/s²
0-3 km storm-relative helicity: 180 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 3.9

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 21, 7:53 PM CDT	Severe Thunderstorm Watch	SPC	Brown, Callahan, Coleman, Collin, Comanche, Cooke and 28 more	6 hr
Oct 21, 8:34 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Clay, Cooke, Denton, Fannin and 10 more	86 min
Oct 21, 10:42 PM CDT	Mesoscale Discussion	SPC	Bowie, Franklin, Lamar, Red River, Titus	93 min
Oct 21, 11:56 PM CDT	Severe Thunderstorm Watch	SPC	Bowie, Camp, Cass, Franklin, Marion, Morris and 4 more	7 hr
Oct 22, 1:44 AM CDT	Mesoscale Discussion	SPC	Bowie, Camp, Cass, Franklin, Morris, Red River and 1 more	91 min
Oct 22, 4:57 AM CDT	Mesoscale Discussion	SPC	Harrison, Panola, Rusk, Shelby	93 min

Nearby

Mesoscale Discussions in Texas, 2017 Every mesoscale discussion in 2017

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.