Alert archive / Texas / Tornado Watches in 2011
Tornado Watch 220
The Storm Prediction Center issued this tornado watch at Apr 26, 2011, 4:56 PM CDT for 15 parishes in Louisiana; 29 counties in Texas. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 26, 2011, 4:56 PM CDT (21:56 UTC)
- Expired
- Apr 26, 2011, 9:51 PM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 4 in
- Strongest gust expected
- 65 kt
All 44 counties
Beauregard Parish, LA, Bienville Parish, LA, Caldwell Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Austin County, TX, Bastrop County, TX, Brazos County, TX, Burleson County, TX, Fayette County, TX, Grimes County, TX, Hardin County, TX, Hays County, TX, Houston County, TX, Jasper County, TX, Lee County, TX, Liberty County, TX, Madison County, TX, Montgomery County, TX, Nacogdoches County, TX, Newton County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Travis County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Williamson County, TX
The radar
The Houston radar (KHGX), 168 km from the middle of the area, began a volume at 21:56 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
- 50%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 70%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 26, 5:11 PM CDT | Severe Thunderstorm Warning | HGX | Houston | 49 min |
| Apr 26, 7:18 PM CDT | Severe Thunderstorm Warning | SHV | Caddo, De Soto | 57 min |
| Apr 26, 7:41 PM CDT | Tornado Warning | SHV | Caddo, De Soto | 49 min |
| Apr 26, 8:25 PM CDT | Tornado Warning | SHV | Bienville, Bossier, Caddo, De Soto, Red River, Webster | 50 min |
| Apr 26, 8:30 PM CDT | Severe Thunderstorm Warning | SHV | Bienville, Bossier, De Soto, Natchitoches, Red River | 45 min |
| Apr 26, 8:46 PM CDT | Tornado Warning | SHV | Bienville, Claiborne, Webster | 32 min |
| Apr 26, 9:05 PM CDT | Tornado Warning | SHV | Bienville, Jackson, Lincoln | 25 min |
| Apr 26, 9:10 PM CDT | Severe Thunderstorm Warning | SHV | Bienville, Jackson | 50 min |
| Apr 26, 9:16 PM CDT | Severe Thunderstorm Warning | SHV | Claiborne, Lincoln, Union | 44 min |
| Apr 26, 9:25 PM CDT | Tornado Warning | SHV | Bienville, Jackson, Lincoln | 35 min |
| Apr 26, 9:49 PM CDT | Tornado Warning | SHV | Jackson, Lincoln, Ouachita, Union | 41 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
Shreveport, LA (KSHV), launched 12:00Z, 9.9 hours before the alert went out and 236 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
- 1650 J/kg
- Mixed-layer CIN
- -50 J/kg
- Mixed-layer LCL
- 566 m above ground
- 0-6 km bulk shear
- 58 kt
- 0-1 km storm-relative helicity
- 148 m²/s²
- 0-3 km storm-relative helicity
- 57 m²/s²
- Significant tornado parameter
- 1.5
- Supercell composite
- 7.2
The text
As transmitted, in the capitals the NWS used until 2016.
804
WWUS20 KWNS 262159
SEL0
SPC WW 262159
LAZ000-TXZ000-270300-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 220
NWS STORM PREDICTION CENTER NORMAN OK
455 PM CDT TUE APR 26 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
CENTRAL AND WESTERN LOUISIANA
SOUTH-CENTRAL AND SOUTHEAST TEXAS
EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 455 PM UNTIL
1000 PM CDT.
TORNADOES...HAIL TO 4 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 10 MILES SOUTHWEST OF AUSTIN
TEXAS TO 30 MILES NORTHEAST OF ALEXANDRIA LOUISIANA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU0).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 213...WW 214...WW
215...WW 216...WW 217...WW 218...WW 219...
DISCUSSION...DEEP-LAYER WIND PROFILES AND FAVORABLY LARGE BUOYANCY
SUPPORT POTENTIAL FOR SVR TSTMS -- INCLUDING SUPERCELLS ALREADY
OCCURRING OVER SRN PORTIONS WW 215 BETWEEN ACT-LFK AND POTENTIAL
DEVELOPMENT FARTHER W ALONG DRYLINE -- TO AFFECT WW AREA LATE
AFTERNOON THROUGH EVENING.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
650. MEAN STORM MOTION VECTOR 26030.
...EDWARDS/HALESSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 25, 7:34 PM CDT | Mesoscale Discussion | SPC | Bossier, Claiborne, Lincoln, Union, Webster | 116 min |
| Apr 25, 9:23 PM CDT | Tornado Watch | SPC | Caldwell, East Carroll, Franklin, Madison, Morehouse, Ouachita and 2 more | 7 hr |
| Apr 25, 9:37 PM CDT | Mesoscale Discussion | SPC | De Soto, Sabine | 83 min |
| Apr 25, 10:47 PM CDT | Tornado Watch | SPC | Allen, Beauregard, Evangeline, Rapides, Sabine, Vernon | 5 hr |
| Apr 25, 11:05 PM CDT | Mesoscale Discussion | SPC | East Carroll, Morehouse, West Carroll | 115 min |
| Apr 26, 1:34 AM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Evangeline, Jefferson Davis, Rapides and 1 more | 86 min |
| Apr 26, 1:52 AM CDT | Severe Thunderstorm Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 7 more | 5 hr |
| Apr 26, 1:11 PM CDT | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 5 more | 2 hr |
| Apr 26, 1:44 PM CDT | Tornado Watch | SPC | Bossier, Caddo, Claiborne, Union, Webster | 10 hr |
| Apr 26, 3:59 PM CDT | Mesoscale Discussion | SPC | Bossier, Caddo, Claiborne, Union, Webster | 91 min |
| Apr 26, 6:43 PM CDT | Mesoscale Discussion | SPC | Beauregard, Bienville, Bossier, Caddo, Caldwell, Claiborne and 13 more | 2 hr |
| Apr 26, 3:01 PM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bastrop, Bee, Bexar, Blanco and 22 more | 89 min |
| Apr 26, 3:15 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Childress, Clay, Collingsworth, Cottle and 16 more | 90 min |
| Apr 26, 3:43 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more | 6 hr |
Nearby
Tornado Watches in Texas, 2011Tornado Watches in Louisiana, 2011Every tornado watch in 2011
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.