Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 457
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 5:41 PM CDT for 10 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2021, 5:41 PM CDT (22:41 UTC)
- Expired
- Apr 28, 2021, 7:45 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 120
Counties Bandera County, TX, Bexar County, TX, Frio County, TX, Kendall County, TX, Kinney County, TX, Maverick County, TX, Medina County, TX, Real County, TX, Uvalde County, TX, Zavala County, TX
The radar
The Laughlin AFB radar (KDFX), 33 km from the middle of the area, began a volume at 22:43 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.
The nearest sounding before it
Del Rio, TX (KDRT), launched 12:00Z, 10.7 hours before the alert went out and 82 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
- 2118 J/kg
- Mixed-layer CIN
- -125 J/kg
- Mixed-layer LCL
- 609 m above ground
- 0-6 km bulk shear
- 68 kt
- 0-1 km storm-relative helicity
- 189 m²/s²
- 0-3 km storm-relative helicity
- 221 m²/s²
- Significant tornado parameter
- 1.6
- Supercell composite
- 4.0
The text
As transmitted.
152
ACUS11 KWNS 282241
SWOMCD
SPC MCD 282241
TXZ000-290045-
Mesoscale Discussion 0457
NWS Storm Prediction Center Norman OK
0541 PM CDT Wed Apr 28 2021
Areas affected...Southwest Texas
Concerning...Tornado Watch 120...
Valid 282241Z - 290045Z
The severe weather threat for Tornado Watch 120 continues.
SUMMARY...A severe threat will continue through early this evening
across parts of southwest Texas. Very large hail, wind damage and a
tornado or two will be possible.
DISCUSSION...The latest radar imagery out of Del Rio shows a cluster
of severe storms located from just southeast of Del Rio extending
westward into the far northern Mexico. The storms will continue to
move eastward along a corridor of moderate instability over the next
few hours. The RAP is showing MLCAPE in the 2500 to 3000 J/kg range
from near Del Rio extending eastward into the southern Texas Hill
Country. The RAP suggests that 700-500 mb lapse rates are near 7.0
C/km. This combined 0-6 km shear in the 50 to 60 kt range, evident
on the WSR-88D VWP, will be favorable for supercells with large
hail. Hailstones of greater than 2 inches in diameter will be
possible with the stronger updrafts. As low-level flow strengthens
early this evening, a tornado threat is expected to develop. Wind
damage can also be expected along the leading edge or within the
stronger downdrafts.
..Broyles.. 04/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EWX...
LAT...LON 29520117 29190128 28980103 28670016 28759916 29379851
29829836 30069877 30029982 29830048 29520117SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 8:01 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Clay, Fisher, Haskell, Jones and 10 more | 89 min |
| Apr 27, 8:23 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Archer, Baylor, Borden, Clay, Coke and 29 more | 7 hr |
| Apr 27, 10:39 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Crane, Dawson, Ector, Howard and 5 more | 2 hr |
| Apr 28, 1:38 AM CDT | Mesoscale Discussion | SPC | Callahan, Coke, Coleman, Eastland, Glasscock, Jones and 10 more | 2 hr |
| Apr 28, 3:01 AM CDT | Tornado Watch | SPC | Archer, Baylor, Callahan, Clay, Cooke, Eastland and 14 more | 7 hr |
| Apr 28, 6:35 AM CDT | Mesoscale Discussion | SPC | Archer, Callahan, Clay, Cooke, Eastland, Jack and 9 more | 3 hr |
| Apr 28, 9:25 AM CDT | Mesoscale Discussion | SPC | Cooke, Denton, Grayson, Parker, Wise | 65 min |
| Apr 28, 1:14 PM CDT | Mesoscale Discussion | SPC | Brown, Callahan, Coleman, Comanche, Cooke, Denton and 14 more | 2 hr |
| Apr 28, 1:57 PM CDT | Tornado Watch | SPC | Brown, Callahan, Coke, Coleman, Comanche, Concho and 16 more | 9 hr |
| Apr 28, 2:42 PM CDT | Mesoscale Discussion | SPC | Bandera, Blanco, Edwards, Gillespie, Kendall, Kerr and 9 more | 2 hr |
| Apr 28, 3:10 PM CDT | Tornado Watch | SPC | Atascosa, Bandera, Bexar, Blanco, Comal, Dimmit and 23 more | 8 hr |
| Apr 28, 3:40 PM CDT | Mesoscale Discussion | SPC | Brown, Callahan, Coleman, Comanche, Eastland, Runnels and 2 more | 95 min |
| Apr 28, 6:01 PM CDT | Mesoscale Discussion | SPC | Lamar | 119 min |
Nearby
Mesoscale Discussions in Texas, 2021Every mesoscale discussion 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.