Alert archive / Texas / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 501
The Storm Prediction Center issued this severe thunderstorm watch at Jul 21, 2012, 6:14 PM CDT for 6 parishes in Louisiana; 48 counties in Texas. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2012, 6:14 PM CDT (23:14 UTC)
- Expired
- Jul 22, 2012, 12:21 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 54 counties
Bossier Parish, LA, Caddo Parish, LA, De Soto Parish, LA, Red River Parish, LA, Sabine Parish, LA, Webster Parish, LA, Anderson County, TX, Angelina County, TX, Bell County, TX, Brazos County, TX, Burleson County, TX, Cherokee County, TX, Collin County, TX, Dallas County, TX, Ellis County, TX, Falls County, TX, Freestone County, TX, Gregg County, TX, Grimes County, TX, Hardin County, TX, Harrison County, TX, Henderson County, TX, Hill County, TX, Houston County, TX, Hunt County, TX, Jasper County, TX, Kaufman County, TX, Leon County, TX, Liberty County, TX, Limestone County, TX, Madison County, TX, McLennan County, TX, Milam County, TX, Montgomery County, TX, Nacogdoches County, TX, Navarro County, TX, Newton County, TX, Panola County, TX, Polk County, TX, Robertson County, TX, Rockwall County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Smith County, TX, Tarrant County, TX, Trinity County, TX, Tyler County, TX, Van Zandt County, TX, Walker County, TX, Waller County, TX, Washington County, TX
The radar
The Ft Hood radar (KGRK), 145 km from the middle of the area, began a volume at 23:17 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
23 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 6:34 PM CDT | Severe Thunderstorm Warning | SHV | Sabine | 56 min |
| Jul 21, 6:40 PM CDT | Severe Thunderstorm Warning | SHV | Bienville, Bossier, Caddo, De Soto, Natchitoches, Red River and 1 more | 65 min |
| Jul 21, 6:47 PM CDT | Severe Thunderstorm Warning | SHV | Cherokee, Smith | 58 min |
| Jul 21, 6:52 PM CDT | Severe Thunderstorm Warning | SHV | Nacogdoches | 53 min |
| Jul 21, 7:03 PM CDT | Severe Thunderstorm Warning | SHV | Panola | 42 min |
| Jul 21, 7:12 PM CDT | Severe Thunderstorm Warning | SHV | Harrison, Marion, Panola | 63 min |
| Jul 21, 7:18 PM CDT | Severe Thunderstorm Warning | FWD | Anderson | 57 min |
| Jul 21, 7:22 PM CDT | Severe Thunderstorm Warning | SHV | De Soto, Natchitoches, Sabine | 53 min |
| Jul 21, 7:24 PM CDT | Severe Thunderstorm Warning | SHV | Nacogdoches, Sabine, San Augustine, Shelby | 66 min |
| Jul 21, 7:40 PM CDT | Severe Thunderstorm Warning | SHV | Cherokee, Nacogdoches, Rusk | 65 min |
| Jul 21, 8:07 PM CDT | Severe Thunderstorm Warning | FWD | Anderson, Freestone, Henderson | 38 min |
| Jul 21, 8:15 PM CDT | Severe Thunderstorm Warning | FWD | Anderson, Henderson | 45 min |
| Jul 21, 8:17 PM CDT | Severe Thunderstorm Warning | SHV | Angelina, Cherokee, Nacogdoches | 58 min |
| Jul 21, 8:25 PM CDT | Severe Thunderstorm Warning | SHV | Cherokee, Nacogdoches | 50 min |
| Jul 21, 8:34 PM CDT | Severe Thunderstorm Warning | HGX | Houston, Polk, Trinity | 56 min |
| Jul 21, 8:44 PM CDT | Severe Thunderstorm Warning | FWD | Anderson, Henderson | 46 min |
| Jul 21, 8:56 PM CDT | Severe Thunderstorm Warning | HGX | Polk, San Jacinto, Trinity | 64 min |
| Jul 21, 9:16 PM CDT | Severe Thunderstorm Warning | SHV | Angelina | 29 min |
| Jul 21, 9:21 PM CDT | Severe Thunderstorm Warning | HGX | Houston, Madison, Polk, San Jacinto, Trinity, Walker | 54 min |
| Jul 21, 9:29 PM CDT | Severe Thunderstorm Warning | FWD | Anderson, Freestone, Henderson | 39 min |
| Jul 21, 9:58 PM CDT | Severe Thunderstorm Warning | HGX | Liberty, Polk, San Jacinto | 47 min |
| Jul 21, 10:14 PM CDT | Severe Thunderstorm Warning | HGX | Polk, San Jacinto, Trinity, Walker | 61 min |
| Jul 21, 10:40 PM CDT | Severe Thunderstorm Warning | HGX | Liberty, Montgomery, Polk, San Jacinto | 50 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Fort Worth, TX (KFWD), launched 12:00Z, 11.2 hours before the alert went out and 223 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.
- Mixed-layer CAPE
- 534 J/kg
- Mixed-layer CIN
- -230 J/kg
- Mixed-layer LCL
- 2199 m above ground
- 0-6 km bulk shear
- 18 kt
- 0-1 km storm-relative helicity
- 46 m²/s²
- 0-3 km storm-relative helicity
- 108 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 7:47 PM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Cameron, Jefferson Davis, Vernon | 88 min |
| Jul 21, 12:45 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 6 more | 3 hr |
| Jul 21, 2:06 PM CDT | Mesoscale Discussion | SPC | Andrews, Archer, Armstrong, Bailey, Baylor, Borden and 64 more | 2 hr |
| Jul 21, 5:37 PM CDT | Mesoscale Discussion | SPC | Anderson, Angelina, Austin, Bastrop, Brazos, Burleson and 31 more | 83 min |
Nearby
Severe Thunderstorm Watches in Texas, 2012Severe Thunderstorm Watches in Louisiana, 2012Every severe thunderstorm watch 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.