Alert archive / Texas / Mesoscale Discussions in 2009

Mesoscale Discussion 501

April 17, 200917 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 17, 2009, 1:45 PM CDT for 17 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 17, 2009, 1:45 PM CDT (18:45 UTC)
Expired: Apr 17, 2009, 3:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Brazoria County, TX, Chambers County, TX, Colorado County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jackson County, TX, Jefferson County, TX, Liberty County, TX, Matagorda County, TX, Montgomery County, TX, Orange County, TX, San Jacinto County, TX, Walker County, TX, Waller County, TX, Wharton County, TX

The radar

The Houston radar (KHGX), 44 km from the middle of the area, began a volume at 18:47 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.

Tornado Watch 162Apr 17, 3:45 PM CDT

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 6.8 hours before the alert went out and 199 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 673 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 129 m²/s²
0-3 km storm-relative helicity: 213 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.0

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 16, 7:31 PM CDT	Mesoscale Discussion	SPC	Brewster, Kinney, Pecos, Terrell, Val Verde	89 min
Apr 16, 7:43 PM CDT	Mesoscale Discussion	SPC	Anderson, Angelina, Cherokee, Dallas, Ellis, Freestone and 23 more	62 min
Apr 16, 8:36 PM CDT	Mesoscale Discussion	SPC	Andrews, Borden, Briscoe, Castro, Childress, Coke and 34 more	84 min
Apr 16, 9:20 PM CDT	Mesoscale Discussion	SPC	Armstrong, Carson, Collingsworth, Dallam, Deaf Smith, Donley and 14 more	55 min
Apr 16, 10:56 PM CDT	Mesoscale Discussion	SPC	Coke, Concho, Crockett, Fisher, Irion, Jones and 11 more	94 min
Apr 16, 11:35 PM CDT	Severe Thunderstorm Watch	SPC	Bandera, Brown, Callahan, Coleman, Comanche, Concho and 26 more	6 hr
Apr 17, 2:32 AM CDT	Mesoscale Discussion	SPC	Brown, Callahan, Coleman, Comanche, Concho, Eastland and 20 more	118 min
Apr 17, 5:16 AM CDT	Mesoscale Discussion	SPC	Blanco, Burnet, Edwards, Gillespie, Kendall, Kerr and 8 more	59 min
Apr 17, 7:28 AM CDT	Mesoscale Discussion	SPC	Atascosa, Bandera, Bastrop, Bell, Bexar, Blanco and 23 more	92 min
Apr 17, 7:48 AM CDT	Severe Thunderstorm Watch	SPC	Atascosa, Bandera, Bastrop, Bell, Bexar, Blanco and 35 more	5 hr
Apr 17, 9:56 AM CDT	Mesoscale Discussion	SPC	Anderson, Angelina, Atascosa, Austin, Bastrop, Bee and 63 more	94 min
Apr 17, 10:24 AM CDT	Tornado Watch	SPC	Austin, Brazoria, Brazos, Burleson, Chambers, Colorado and 17 more	7 hr
Apr 17, 12:10 PM CDT	Mesoscale Discussion	SPC	Anderson, Angelina, Austin, Brazos, Cherokee, Colorado and 19 more	3 hr
Apr 17, 12:38 PM CDT	Mesoscale Discussion	SPC	Atascosa, Bee, DeWitt, Goliad, Gonzales, Karnes and 7 more	37 min
Apr 17, 12:51 PM CDT	Severe Thunderstorm Watch	SPC	Atascosa, Bee, Calhoun, DeWitt, Fayette, Frio and 10 more	5 hr
Apr 17, 3:19 PM CDT	Mesoscale Discussion	SPC	Aransas, Atascosa, Bastrop, Bee, Bell, Bexar and 31 more	56 min
Apr 17, 3:24 PM CDT	Mesoscale Discussion	SPC	Childress, Collingsworth, Cottle, Foard, Gray, Hansford and 13 more	96 min
Apr 17, 3:44 PM CDT	Tornado Watch	SPC	Aransas, Austin, Bee, Brazoria, Calhoun, Chambers and 22 more	6 hr
Apr 17, 5:00 PM CDT	Severe Thunderstorm Watch	SPC	Baylor, Childress, Collingsworth, Cottle, Foard, Hardeman and 13 more	5 hr
Apr 17, 6:50 PM CDT	Mesoscale Discussion	SPC	Aransas, Bee, Brazoria, Calhoun, Chambers, Colorado and 18 more	85 min

Nearby

Mesoscale Discussions in Texas, 2009 Every mesoscale discussion in 2009

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.