Alert archive / Texas / Mesoscale Discussions in 2013

Mesoscale Discussion 516

April 18, 2013Marshall County, Oklahoma; 26 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2013, 4:29 AM CDT for Marshall County, Oklahoma; 26 counties in Texas. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2013, 4:29 AM CDT (09:29 UTC)
Expired: Apr 18, 2013, 6:00 AM CDT
In force: 91 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 121

All 27 counties

Marshall County, OK, Bosque County, TX, Brown County, TX, Coleman County, TX, Collin County, TX, Comanche County, TX, Concho County, TX, Cooke County, TX, Dallas County, TX, Denton County, TX, Eastland County, TX, Ellis County, TX, Erath County, TX, Grayson County, TX, Hamilton County, TX, Hood County, TX, Hunt County, TX, Johnson County, TX, McCulloch County, TX, Mills County, TX, Palo Pinto County, TX, Parker County, TX, Rockwall County, TX, San Saba County, TX, Somervell County, TX, Tarrant County, TX, Wise County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 76 km from the middle of the area, began a volume at 09:32 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, 9.5 hours before the alert went out and 92 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: 790 J/kg
Mixed-layer CIN: -89 J/kg
Mixed-layer LCL: 1376 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 196 m²/s²
0-3 km storm-relative helicity: 329 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 15.0

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
Apr 17, 8:36 PM CDT	Mesoscale Discussion	SPC	Caddo, Canadian, Carter, Cherokee, Cleveland, Coal and 41 more	84 min
Apr 17, 10:37 PM CDT	Mesoscale Discussion	SPC	Caddo, Canadian, Carter, Cherokee, Cleveland, Comanche and 35 more	53 min
Apr 17, 10:47 PM CDT	Tornado Watch	SPC	Adair, Atoka, Bryan, Carter, Cherokee, Coal and 28 more	7 hr
Apr 17, 11:46 PM CDT	Mesoscale Discussion	SPC	Craig, Ottawa	89 min
Apr 18, 2:01 AM CDT	Mesoscale Discussion	SPC	Adair, Cherokee, Delaware, Haskell, Hughes, Latimer and 7 more	89 min
Apr 18, 4:02 AM CDT	Mesoscale Discussion	SPC	Haskell, Latimer, LeFlore, McCurtain, Pushmataha, Sequoyah	58 min
Apr 17, 7:30 PM CDT	Mesoscale Discussion	SPC	Zavala	90 min
Apr 17, 10:47 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Brown, Callahan, Clay, Coke, Coleman and 32 more	7 hr
Apr 17, 11:44 PM CDT	Mesoscale Discussion	SPC	Archer, Brown, Callahan, Coke, Coleman, Concho and 19 more	91 min

Nearby

Mesoscale Discussions in Texas, 2013 Mesoscale Discussions in Oklahoma, 2013 Every mesoscale discussion in 2013

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.