Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 794
The Storm Prediction Center issued this mesoscale discussion at May 28, 2021, 7:58 PM CDT for 8 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 28, 2021, 7:58 PM CDT (00:58 UTC)
- Expired
- May 28, 2021, 10:00 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 221
Counties Bandera County, TX, Bexar County, TX, Comal County, TX, Gonzales County, TX, Guadalupe County, TX, Medina County, TX, Uvalde County, TX, Wilson County, TX
The radar
The Austin/San Antonio radar (KEWX), 68 km from the middle of the area, began a volume at 00:59 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 00:00Z, 1.0 hours before the alert went out and 207 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
- 3576 J/kg
- Mixed-layer CIN
- -62 J/kg
- Mixed-layer LCL
- 1255 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 14 m²/s²
- 0-3 km storm-relative helicity
- 166 m²/s²
- Significant tornado parameter
- 3.0
- Supercell composite
- 14.8
The text
As transmitted.
706
ACUS11 KWNS 290059
SWOMCD
SPC MCD 290058
TXZ000-290300-
Mesoscale Discussion 0794
NWS Storm Prediction Center Norman OK
0758 PM CDT Fri May 28 2021
Areas affected...Parts of south central Texas
Concerning...Severe Thunderstorm Watch 221...
Valid 290058Z - 290300Z
The severe weather threat for Severe Thunderstorm Watch 221
continues.
SUMMARY...A rapid increase and intensification of thunderstorm
activity appears possible across the Greater San Antonio area
through 9-10 PM CDT, posing a risk for frequent cloud to ground
lightning, large, potentially damaging hail, heavy rainfall and a
few strong downbursts.
DISCUSSION...Large-scale ascent associated with a zone of enhanced
warm advection along a mid-level baroclinic zone, coupled with lift
along and above southward advancing cold pools may contribute to
rapidly increasing and intensifying thunderstorm development across
the Greater San Antonio area between now and 02-03Z. A seasonably
moist boundary layer across this region appears characterized by
large CAPE of 3000-4000 J/kg, in the presence of modest to weak, but
strongly sheared westerly deep-layer ambient mean flow.
A couple of supercell structures are ongoing along the southward
advancing cold pools, with potential for considerable further
upscale growth and organization, posing a risk for large, damaging
hail and, increasingly, strong surface gusts near and south of San
Antonio.
..Kerr.. 05/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...EWX...
LAT...LON 29929916 29919866 29779747 29239713 28949858 29279987
29749970 29929916SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 28, 7:18 PM CDT | Mesoscale Discussion | SPC | Crane, Crockett, Ector, Kimble, Reagan, Schleicher and 4 more | 87 min |
| May 28, 7:40 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Bailey, Borden, Castro, Cochran, Crosby and 16 more | 6 hr |
| May 28, 9:12 PM CDT | Mesoscale Discussion | SPC | Andrews, Gaines, Hockley, Lubbock, Lynn, Terry | 93 min |
| May 28, 10:15 PM CDT | Mesoscale Discussion | SPC | Bee, Brazoria, Calhoun, Fort Bend, Goliad, Jackson and 5 more | 90 min |
| May 28, 11:22 PM CDT | Mesoscale Discussion | SPC | Crane, Pecos, Reeves, Upton, Ward, Winkler | 113 min |
| May 29, 1:34 AM CDT | Mesoscale Discussion | SPC | Crockett, Dimmit, Edwards, Frio, Kimble, Kinney and 10 more | 2 hr |
| May 29, 10:09 AM CDT | Mesoscale Discussion | SPC | Brooks, Cameron, Hidalgo, Jim Hogg, Kenedy, Starr and 1 more | 96 min |
| May 29, 2:51 PM CDT | Mesoscale Discussion | SPC | Culberson, Hudspeth, Jeff Davis, Loving, Presidio, Reeves | 114 min |
| May 29, 6:30 PM CDT | Mesoscale Discussion | SPC | Dallam, Hartley, Moore | 90 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.