Alert archive / Texas / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 184
The Storm Prediction Center issued this severe thunderstorm watch at May 17, 2021, 6:40 PM CDT for 6 counties in Texas. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- May 17, 2021, 6:40 PM CDT (23:40 UTC)
- Expired
- May 17, 2021, 11:00 PM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 3.5 in
- Strongest gust expected
- 60 kt
Counties Dimmit County, TX, Frio County, TX, La Salle County, TX, Maverick County, TX, Webb County, TX, Zavala County, TX
The radar
The Laughlin AFB radar (KDFX), 137 km from the middle of the area, began a volume at 23:41 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
- 20%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 50%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 6:50 PM CDT | Severe Thunderstorm Warning | EWX | Dimmit | 25 min |
| May 17, 7:14 PM CDT | Severe Thunderstorm Warning | EWX | Dimmit | 26 min |
| May 17, 7:42 PM CDT | Severe Thunderstorm Warning | CRP | La Salle, Webb | 48 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
Del Rio, TX (KDRT), launched 12:00Z, 11.7 hours before the alert went out and 186 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
- 2620 J/kg
- Mixed-layer CIN
- -127 J/kg
- Mixed-layer LCL
- 577 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 85 m²/s²
- 0-3 km storm-relative helicity
- 181 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 2.5
The text
As transmitted.
292
WWUS20 KWNS 172337
SEL4
SPC WW 172337
TXZ000-180400-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 184
NWS Storm Prediction Center Norman OK
640 PM CDT Mon May 17 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
South Texas
* Effective this Monday evening from 640 PM until 1100 PM CDT.
* Primary threats include...
Isolated very large hail events to 3.5 inches in diameter
possible
Isolated damaging wind gusts to 70 mph possible
A tornado or two possible
SUMMARY...A lone supercell may remain nearly stationary along a
boundary across a portion of south Texas. While the spatial extent
of the severe threat may be rather isolated, this supercell may
become intense before weakening later this evening.
The severe thunderstorm watch area is approximately along and 40
statute miles east and west of a line from 40 miles north northwest
of Cotulla TX to 55 miles south of Cotulla TX. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU4).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 181...WW 182...WW 183...
AVIATION...A few severe thunderstorms with hail surface and aloft to
3.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 600. Mean storm motion vector
29010.
...GramsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 16, 7:08 PM CDT | Severe Thunderstorm Watch | SPC | Cottle, Crosby, Dickens, Floyd, Garza, Hale and 8 more | 6 hr |
| May 16, 8:54 PM CDT | Mesoscale Discussion | SPC | Briscoe, Cottle, Foard, Hall, King, Knox and 1 more | 96 min |
| May 16, 9:38 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Baylor, Clay, Foard, Hardeman, Haskell and 10 more | 4 hr |
| May 16, 10:46 PM CDT | Mesoscale Discussion | SPC | Baylor, Cottle, Dickens, Foard, Haskell, King and 3 more | 59 min |
| May 17, 1:09 AM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Clay, Crosby, Dickens, Fisher and 17 more | 96 min |
| May 17, 9:18 AM CDT | Mesoscale Discussion | SPC | Jasper, Jefferson, Newton, Orange | 117 min |
| May 17, 12:47 PM CDT | Mesoscale Discussion | SPC | Austin, Bastrop, Bell, Blanco, Brazoria, Brazos and 29 more | 88 min |
| May 17, 1:39 PM CDT | Mesoscale Discussion | SPC | Dallam, Hartley, Oldham | 2 hr |
| May 17, 2:11 PM CDT | Mesoscale Discussion | SPC | Andrews, Bailey, Borden, Castro, Cochran, Crane and 20 more | 2 hr |
| May 17, 2:39 PM CDT | Severe Thunderstorm Watch | SPC | Armstrong, Carson, Collingsworth, Dallam, Donley, Gray and 10 more | 8 hr |
| May 17, 3:04 PM CDT | Tornado Watch | SPC | Andrews, Bailey, Borden, Briscoe, Castro, Cochran and 39 more | 8 hr |
| May 17, 4:44 PM CDT | Tornado Watch | SPC | Baylor, Childress, Cottle, Fisher, Foard, Hardeman and 10 more | 6 hr |
| May 17, 4:53 PM CDT | Mesoscale Discussion | SPC | Baylor, Callahan, Childress, Cottle, Fisher, Foard and 11 more | 97 min |
| May 17, 5:10 PM CDT | Mesoscale Discussion | SPC | Dallam, Hansford, Hartley, Hutchinson, Moore, Ochiltree and 3 more | 2 hr |
| May 17, 5:36 PM CDT | Mesoscale Discussion | SPC | Andrews, Armstrong, Bailey, Borden, Briscoe, Castro and 38 more | 84 min |
| May 17, 6:13 PM CDT | Mesoscale Discussion | SPC | Dimmit, La Salle, Webb | 92 min |
Nearby
Severe Thunderstorm Watches in Texas, 2021Every severe thunderstorm 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.