Alert archive / Texas / Tornado Watches in 2011
Tornado Watch 127
The Storm Prediction Center issued this tornado watch at Apr 11, 2011, 1:49 AM CDT for 7 counties in Arkansas; McCurtain County, Oklahoma; 20 counties in Texas. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 11, 2011, 1:49 AM CDT (06:49 UTC)
- Expired
- Apr 11, 2011, 6:00 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 28 counties
Hempstead County, AR, Howard County, AR, Lafayette County, AR, Little River County, AR, Miller County, AR, Nevada County, AR, Sevier County, AR, McCurtain County, OK, Bowie County, TX, Camp County, TX, Cass County, TX, Delta County, TX, Franklin County, TX, Gregg County, TX, Harrison County, TX, Hopkins County, TX, Hunt County, TX, Kaufman County, TX, Lamar County, TX, Marion County, TX, Morris County, TX, Rains County, TX, Red River County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX
The radar
The Shreveport radar (KSHV), 137 km from the middle of the area, began a volume at 06:46 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
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- 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
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
9 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 11, 1:53 AM CDT | Severe Thunderstorm Warning | FWD | Henderson, Kaufman | 52 min |
| Apr 11, 2:01 AM CDT | Tornado Warning | FWD | Dallas, Kaufman | 30 min |
| Apr 11, 2:13 AM CDT | Tornado Warning | FWD | Hunt, Kaufman, Rockwall | 35 min |
| Apr 11, 2:19 AM CDT | Severe Thunderstorm Warning | FWD | Rains, Van Zandt | 56 min |
| Apr 11, 2:38 AM CDT | Severe Thunderstorm Warning | FWD | Delta, Hopkins, Hunt | 52 min |
| Apr 11, 2:59 AM CDT | Severe Thunderstorm Warning | SHV | Franklin, Wood | 31 min |
| Apr 11, 3:20 AM CDT | Severe Thunderstorm Warning | SHV | Camp, Franklin, Morris, Red River, Titus, Upshur and 1 more | 40 min |
| Apr 11, 3:44 AM CDT | Severe Thunderstorm Warning | SHV | McCurtain | 40 min |
| Apr 11, 4:00 AM CDT | Severe Thunderstorm Warning | SHV | Little River, Miller | 45 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 00:00Z, 6.8 hours before the alert went out and 143 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
- 433 J/kg
- Mixed-layer CIN
- -317 J/kg
- Mixed-layer LCL
- 1903 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 81 m²/s²
- 0-3 km storm-relative helicity
- 149 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
342
WWUS20 KWNS 110647
SEL7
SPC WW 110647
ARZ000-OKZ000-TXZ000-111100-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 127
NWS STORM PREDICTION CENTER NORMAN OK
150 AM CDT MON APR 11 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
SOUTHWEST ARKANSAS
EXTREME SOUTHEAST OKLAHOMA
NORTHEAST TEXAS
EFFECTIVE THIS MONDAY MORNING FROM 150 AM UNTIL 600 AM CDT.
TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE
MILES EAST AND WEST OF A LINE FROM 10 MILES WEST SOUTHWEST OF
TYLER TEXAS TO 35 MILES EAST NORTHEAST OF DE QUEEN ARKANSAS. FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).
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 123...WW 124...WW 126...
DISCUSSION...CLUSTERS OF INTENSE THUNDERSTORMS...INCLUDING BOW
ECHOES...ARE TRACK NORTHEASTWARD ACROSS NORTHEAST TX. THESE STORMS
WILL PROGRESS ACROSS THE WATCH AREA THROUGH THE EARLY MORNING HOURS.
DAMAGING WINDS ARE THE GREATEST THREAT. HOWEVER...STRONG LOW LEVEL
VERTICAL SHEAR AND BOW/LEWP STRUCTURES WILL POSE A THREAT FOR
ISOLATED TORNADOES.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 25035.
...HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 10, 7:28 PM CDT | Tornado Watch | SPC | Baxter, Benton, Boone, Carroll, Crawford, Franklin and 7 more | 8 hr |
| Apr 10, 8:52 PM CDT | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Crawford, Madison, Washington | 53 min |
| Apr 11, 2:04 AM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Conway, Crawford and 17 more | 56 min |
| Apr 11, 4:19 AM CDT | Mesoscale Discussion | SPC | Calhoun, Clark, Cleburne, Cleveland, Columbia, Conway and 28 more | 56 min |
| Apr 11, 9:46 AM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 10 more | 29 min |
| Apr 11, 10:31 AM CDT | Tornado Watch | SPC | Arkansas, Bradley, Cleveland, Crittenden, Desha, Drew and 6 more | 6 hr |
| Apr 11, 12:37 PM CDT | Mesoscale Discussion | SPC | Arkansas, Bradley, Cleveland, Crittenden, Desha, Drew and 6 more | 53 min |
| Apr 10, 7:02 PM CDT | Severe Thunderstorm Watch | SPC | Bosque, Brown, Callahan, Coleman, Collin, Comanche and 41 more | 8 hr |
| Apr 10, 9:09 PM CDT | Mesoscale Discussion | SPC | Brown, Callahan, Coleman, Comanche, Concho, Cooke and 21 more | 66 min |
| Apr 10, 11:39 PM CDT | Tornado Watch | SPC | Anderson, Bandera, Bell, Blanco, Bosque, Burnet and 28 more | 7 hr |
| Apr 11, 1:27 AM CDT | Mesoscale Discussion | SPC | Anderson, Bell, Blanco, Bosque, Brown, Burnet and 36 more | 93 min |
Nearby
Tornado Watches in Texas, 2011Tornado Watches in Arkansas, 2011Tornado Watches in Oklahoma, 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.