Alert archive / Texas / Mesoscale Discussions in 2015

Mesoscale Discussion 477

April 27, 20159 counties in Oklahoma; 18 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2015, 3:42 AM CDT for 9 counties in Oklahoma; 18 counties in Texas. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Apr 27, 2015, 3:42 AM CDT (08:42 UTC)
Expired: Apr 27, 2015, 5:15 AM CDT
In force: 93 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 27 counties

Carter County, OK, Cotton County, OK, Jefferson County, OK, Johnston County, OK, Love County, OK, Marshall County, OK, Murray County, OK, Stephens County, OK, Tillman County, OK, Archer County, TX, Baylor County, TX, Clay County, TX, Cooke County, TX, Denton County, TX, Foard County, TX, Grayson County, TX, Hardeman County, TX, Jack County, TX, King County, TX, Knox County, TX, Montague County, TX, Parker County, TX, Throckmorton County, TX, Wichita County, TX, Wilbarger County, TX, Wise County, TX, Young County, TX

The radar

The Altus AFB radar (KFDR), 81 km from the middle of the area, began a volume at 08:42 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, 8.7 hours before the alert went out and 150 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: 1199 J/kg
Mixed-layer CIN: -82 J/kg
Mixed-layer LCL: 1646 m above ground
0-6 km bulk shear: 59 kt
0-1 km storm-relative helicity: 68 m²/s²
0-3 km storm-relative helicity: 248 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 3.3

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 26, 7:10 PM CDT	Mesoscale Discussion	SPC	Beckham, Comanche, Cotton, Greer, Harmon, Jackson and 2 more	65 min
Apr 26, 7:59 PM CDT	Severe Thunderstorm Watch	SPC	Bandera, Bexar, Blanco, Brown, Burnet, Coleman and 24 more	6 hr
Apr 26, 9:29 PM CDT	Mesoscale Discussion	SPC	Dallas, Ellis, Hood, Hunt, Johnson, Kaufman and 4 more	91 min
Apr 26, 10:45 PM CDT	Tornado Watch	SPC	Anderson, Bell, Bosque, Comanche, Coryell, Ellis and 19 more	5 hr
Apr 27, 12:49 AM CDT	Mesoscale Discussion	SPC	Anderson, Angelina, Atascosa, Austin, Bastrop, Bexar and 49 more	86 min
Apr 27, 1:27 AM CDT	Tornado Watch	SPC	Angelina, Atascosa, Austin, Bastrop, Bee, Brazos and 50 more	6 hr
Apr 27, 4:56 AM CDT	Mesoscale Discussion	SPC	Angelina, Chambers, Hardin, Harris, Jasper, Jefferson and 13 more	2 hr
Apr 27, 5:25 AM CDT	Mesoscale Discussion	SPC	Brooks, Kenedy	95 min
Apr 27, 6:01 AM CDT	Tornado Watch	SPC	Jefferson, Orange	7 hr
Apr 27, 1:08 PM CDT	Mesoscale Discussion	SPC	Angelina, Chambers, Hardin, Jasper, Jefferson, Liberty and 9 more	97 min
Apr 27, 3:29 PM CDT	Mesoscale Discussion	SPC	Austin, Bastrop, Bell, Bosque, Brazos, Burleson and 22 more	91 min

Nearby

Mesoscale Discussions in Texas, 2015 Mesoscale Discussions in Oklahoma, 2015 Every mesoscale discussion in 2015

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.