Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 462
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 9:13 PM CDT for 10 counties in Texas. It was in force for 92 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2021, 9:13 PM CDT (02:13 UTC)
- Expired
- Apr 28, 2021, 10:45 PM CDT
- In force
- 92 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 121
Counties Bastrop County, TX, Bexar County, TX, Caldwell County, TX, Colorado County, TX, Comal County, TX, Fayette County, TX, Gonzales County, TX, Guadalupe County, TX, Lavaca County, TX, Wilson County, TX
The radar
The Austin/San Antonio radar (KEWX), 40 km from the middle of the area, began a volume at 02:13 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Corpus Christi, TX (KCRP), launched 00:00Z, 2.2 hours before the alert went out and 219 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
- 2321 J/kg
- Mixed-layer CIN
- -348 J/kg
- Mixed-layer LCL
- 1029 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 114 m²/s²
- 0-3 km storm-relative helicity
- 121 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted.
377
ACUS11 KWNS 290213
SWOMCD
SPC MCD 290213
TXZ000-290345-
Mesoscale Discussion 0462
NWS Storm Prediction Center Norman OK
0913 PM CDT Wed Apr 28 2021
Areas affected...South-central and Southeast Texas
Concerning...Tornado Watch 121...
Valid 290213Z - 290345Z
The severe weather threat for Tornado Watch 121 continues.
SUMMARY...A threat for large hail, wind damage and possibly a
tornado will continue over the next few hours across parts of
south-central and southeast Texas. Weather watch issuance may be
needed to the east of WW 121.
DISCUSSION...Latest radar imagery shows a cluster of severe
thunderstorms located from near San Antonio extending
west-southwestward about 80 statute miles. These storms are located
along the northern edge of a pocket of strong instability, with the
RAP analyzing a pocket of MLCAPE in the 4000 to 4500 J/kg range.
These storms will continue to move eastward over the next few hours,
reaching the Texas Coastal Plains later this evening. Although
instability is less further to the east, strong deep-layer shear is
still present suggesting that a severe threat will continue. A new
weather watch will need to be considered as the storms move toward
the eastern edge of WW 121. Large hail and wind damage will be the
primary threats, although a tornado can not be ruled out.
..Broyles.. 04/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...EWX...
LAT...LON 30239684 30169651 29709638 29419664 29259719 29149803
29129833 29219845 29549859 29639859 29789853 29999832
30229737 30239684SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 7:01 PM CDT | Mesoscale Discussion | SPC | Bastrop, Bexar, Caldwell, Comal, Gonzales, Guadalupe and 4 more | 89 min |
| Apr 28, 7:31 PM CDT | Mesoscale Discussion | SPC | Callahan, Coleman, Collin, Comanche, Cooke, Dallas and 24 more | 119 min |
| Apr 28, 7:55 PM CDT | Tornado Watch | SPC | Bosque, Collin, Comanche, Dallas, Delta, Denton and 29 more | 6 hr |
| Apr 28, 9:19 PM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Collin, Dallas, Delta and 18 more | 116 min |
| Apr 28, 10:22 PM CDT | Tornado Watch | SPC | Atascosa, Bandera, Bastrop, Bexar, Blanco, Burnet and 27 more | 7 hr |
| Apr 28, 11:03 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bandera, Bastrop, Bell, Bexar, Blanco and 37 more | 117 min |
| Apr 29, 1:09 AM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Collin, Dallas, Delta and 22 more | 2 hr |
| Apr 29, 2:01 AM CDT | Tornado Watch | SPC | Bowie, Camp, Cass, Delta, Franklin, Gregg and 15 more | 6 hr |
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.