Alert archive / Texas / Tornado Watches in 2021

Tornado Watch 188

May 18, 202136 counties in Texas

The Storm Prediction Center issued this tornado watch at May 18, 2021, 2:29 PM CDT for 36 counties in Texas. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
May 18, 2021, 2:29 PM CDT (19:29 UTC)
Expired
May 18, 2021, 9:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 36 counties

Anderson County, TX, Atascosa County, TX, Austin County, TX, Bastrop County, TX, Bexar County, TX, Blanco County, TX, Brazos County, TX, Burleson County, TX, Caldwell County, TX, Colorado County, TX, Comal County, TX, DeWitt County, TX, Fayette County, TX, Freestone County, TX, Gonzales County, TX, Grimes County, TX, Guadalupe County, TX, Hays County, TX, Houston County, TX, Karnes County, TX, Kendall County, TX, Lavaca County, TX, Lee County, TX, Leon County, TX, Madison County, TX, Milam County, TX, Montgomery County, TX, Robertson County, TX, San Jacinto County, TX, Travis County, TX, Trinity County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Williamson County, TX, Wilson County, TX

The radar

The Ft Hood radar (KGRK), 104 km from the middle of the area, began a volume at 19:29 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
10%
Ten or more severe wind reports
60%
One or more gusts of 65 knots or more
20%
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
80%

Warnings issued inside it

23 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
May 18, 2:46 PM CDTSevere Thunderstorm WarningEWXComal, Hays59 min
May 18, 3:35 PM CDTSevere Thunderstorm WarningEWXCaldwell, Comal, Guadalupe55 min
May 18, 3:40 PM CDTSevere Thunderstorm WarningEWXCaldwell, Comal, Hays, Travis65 min
May 18, 3:59 PM CDTFlash Flood Warning Considerable damage threatEWXComal3 hr
May 18, 4:24 PM CDTSevere Thunderstorm WarningEWXCaldwell, Gonzales, Guadalupe66 min
May 18, 4:27 PM CDTSevere Thunderstorm WarningEWXBastrop, Caldwell, Fayette, Gonzales, Lee, Travis63 min
May 18, 4:39 PM CDTSevere Thunderstorm WarningEWXFayette, Gonzales, Lavaca66 min
May 18, 4:48 PM CDTTornado WarningEWXLavaca27 min
May 18, 5:21 PM CDTFlash Flood Warning Considerable damage threatEWXCaldwell, Gonzales, Guadalupe3 hr
May 18, 5:42 PM CDTSevere Thunderstorm WarningEWXAtascosa, Frio24 min
May 18, 6:14 PM CDTTornado WarningEWXFayette31 min
May 18, 6:26 PM CDTTornado WarningEWXFayette34 min
May 18, 6:39 PM CDTTornado WarningEWXLavaca51 min
May 18, 6:41 PM CDTTornado Warning Tornado observedEWXFayette34 min
May 18, 6:44 PM CDTFlash Flood Warning Considerable damage threatEWXFayette, Gonzales, Lavaca8 hr
May 18, 7:13 PM CDTTornado WarningEWXFayette32 min
May 18, 7:25 PM CDTTornado WarningEWXLavaca20 min
May 18, 7:33 PM CDTTornado WarningHGXColorado27 min
May 18, 7:53 PM CDTFlash Flood Warning Considerable damage threatEWXFayette, Lavaca4 hr
May 18, 8:23 PM CDTFlash Flood Warning Considerable damage threatEWXDeWitt, Gonzales, Lavaca4 hr
May 18, 8:24 PM CDTTornado WarningHGXAustin, Colorado, Fort Bend, Waller, Wharton36 min
May 18, 8:41 PM CDTSevere Thunderstorm WarningHGXAustin, Colorado, Fort Bend, Waller, Wharton49 min
May 18, 8:52 PM CDTFlash Flood WarningHGXAustin, Burleson, Colorado, Waller, Washington, Wharton113 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, 7.5 hours before the alert went out and 260 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-pSkew-T log-p diagram, Fort Worth, TX at 12:00Z on 2021-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Fort Worth, TX at 12:00Z on 2021-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 252 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
1327 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
252 m²/s²
0-3 km storm-relative helicity
238 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

859 
WWUS20 KWNS 181927
SEL8  
SPC WW 181927
TXZ000-190200-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 188
NWS Storm Prediction Center Norman OK
230 PM CDT Tue May 18 2021

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  South-central/East-Central Texas

* Effective this Tuesday afternoon and evening from 230 PM until
  900 PM CDT.

* Primary threats include...
  A couple tornadoes possible
  Scattered damaging wind gusts to 70 mph likely
  Scattered large hail and isolated very large hail events to 2
    inches in diameter possible

SUMMARY...Increasing severe thunderstorm development is expected
initially across south-central/east-central Texas through mid/late
afternoon, particularly in vicinity of an outflow boundary that has
generally stalled in a southwest/northeast fashion across the
region. A moist environment, modest strength low-level winds in
conjunction with the influence of the outflow boundary could support
a tornado risk aside from more prevalent damaging winds and isolated
large hail.

The tornado watch area is approximately along and 80 statute miles
east and west of a line from 65 miles northwest of Lufkin TX to 55
miles south southeast of San Antonio TX. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU8).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

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 24020.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 17, 7:04 PM CDTMesoscale DiscussionSPCArcher, Bosque, Brown, Clay, Comanche, Eastland and 15 more86 min
May 17, 7:23 PM CDTMesoscale DiscussionSPCCarson, Dallam, Gray, Hansford, Hartley, Hemphill and 8 more2 hr
May 17, 7:32 PM CDTTornado WatchSPCBrown, Callahan, Coke, Coleman, Concho, McCulloch and 4 more3 hr
May 17, 7:37 PM CDTMesoscale DiscussionSPCCallahan, Coke, Coleman, Glasscock, Howard, Jones and 6 more83 min
May 17, 8:04 PM CDTSevere Thunderstorm WatchSPCArcher, Clay, Comanche, Eastland, Erath, Hamilton and 11 more5 hr
May 17, 8:34 PM CDTMesoscale DiscussionSPCAtascosa, Dimmit, Frio, La Salle, McMullen, Maverick and 2 more116 min
May 17, 9:28 PM CDTMesoscale DiscussionSPCCarson, Collingsworth, Donley, Gray, Hansford, Hemphill and 7 more2 hr
May 17, 9:44 PM CDTMesoscale DiscussionSPCArmstrong, Borden, Briscoe, Childress, Collingsworth, Cottle and 15 more91 min
May 17, 10:23 PM CDTMesoscale DiscussionSPCArcher, Brown, Callahan, Clay, Coke, Coleman and 16 more97 min
May 17, 10:35 PM CDTMesoscale DiscussionSPCAndrews, Borden, Brewster, Crane, Crockett, Dawson and 13 more85 min
May 17, 10:58 PM CDTSevere Thunderstorm WatchSPCAndrews, Borden, Brown, Coke, Coleman, Concho and 22 more7 hr
May 17, 11:37 PM CDTMesoscale DiscussionSPCBosque, Brown, Comanche, Denton, Eastland, Erath and 9 more83 min
May 18, 1:02 AM CDTMesoscale DiscussionSPCBrooks, Duval, Jim Hogg58 min
May 18, 1:29 AM CDTMesoscale DiscussionSPCCoke, Concho, Crane, Crockett, Ector, Glasscock and 13 more91 min
May 18, 5:07 AM CDTMesoscale DiscussionSPCCoke, Concho, Irion, Reagan, Runnels, Schleicher and 2 more53 min
May 18, 1:18 PM CDTMesoscale DiscussionSPCAtascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 28 more117 min
May 18, 1:57 PM CDTMesoscale DiscussionSPCBailey, Castro, Deaf Smith, Parmer, Randall, Swisher3 hr
May 18, 2:30 PM CDTMesoscale DiscussionSPCBowie, Camp, Cass, Cherokee, Franklin, Gregg and 12 more2 hr
May 18, 3:51 PM CDTSevere Thunderstorm WatchSPCBowie, Camp, Cass, Cherokee, Franklin, Gregg and 11 more5 hr
May 18, 3:52 PM CDTMesoscale DiscussionSPCBastrop, Caldwell, Colorado, Fayette, Gonzales, Guadalupe and 2 more83 min
May 18, 5:10 PM CDTMesoscale DiscussionSPCLa Salle, McMullen, Webb95 min
May 18, 5:39 PM CDTMesoscale DiscussionSPCBowie, Cass, Gregg, Harrison, Marion, Morris and 1 more2 hr
May 18, 6:07 PM CDTMesoscale DiscussionSPCArmstrong, Borden, Briscoe, Carson, Castro, Cochran and 17 more113 min
May 18, 6:13 PM CDTMesoscale DiscussionSPCAustin, Brazos, Burleson, Colorado, DeWitt, Fayette and 14 more92 min

Nearby

Tornado Watches in Texas, 2021Every tornado watch in 2021

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.