Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 831
The Storm Prediction Center issued this mesoscale discussion at May 31, 2021, 10:07 PM CDT for Dimmit County, Maverick County, Zavala County, Texas. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- May 31, 2021, 10:07 PM CDT (03:07 UTC)
- Expired
- May 31, 2021, 11:30 PM CDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 231
Counties Dimmit County, TX, Maverick County, TX, Zavala County, TX
The radar
The Laughlin AFB radar (KDFX), 93 km from the middle of the area, began a volume at 03:08 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
Del Rio, TX (KDRT), launched 00:00Z, 3.1 hours before the alert went out and 113 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
- 2624 J/kg
- Mixed-layer CIN
- -5 J/kg
- Mixed-layer LCL
- 922 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 51 m²/s²
- 0-3 km storm-relative helicity
- 176 m²/s²
- Significant tornado parameter
- 2.8
- Supercell composite
- 11.0
The text
As transmitted.
321
ACUS11 KWNS 010308
SWOMCD
SPC MCD 010307
TXZ000-010430-
Mesoscale Discussion 0831
NWS Storm Prediction Center Norman OK
1007 PM CDT Mon May 31 2021
Areas affected...The Rio Grande River vicinity of south central
Texas
Concerning...Severe Thunderstorm Watch 231...
Valid 010307Z - 010430Z
The severe weather threat for Severe Thunderstorm Watch 231
continues.
SUMMARY...An organizing cluster of thunderstorms may pose increasing
risk for strong surface gusts across the Rio Grande River vicinity
between Del Rio and Laredo, into adjacent portions of southern Texas
through 11 PM-1 AM CDT. Trends are being monitored for the
possibility of an additional severe weather watch to the south of
Severe Thunderstorm Watch 231.
DISCUSSION...The northern (now southwest of Del Rio, TX) of a pair
of southeastward propagating supercells appears to be undergoing
upscale growth, with convection beginning to increase along the
leading edge of strong convective outflow to the south of the
mid-level cyclonic circulation center. A moist boundary layer
(including surface dew points just above 70F) near the Rio Grande
River, into the higher terrain west of the river, remains
characterized by mixed-layer CAPE in excess of 2000 J/kg, with CAPE
perhaps as large as 1500 J/kg into areas just southwest of San
Antonio and west of Brownsville. 25-30 kt southeasterly inflow of
this air mass may support considerable further upscale growth during
the next couple of hours.
Based on evening soundings, lower/mid-levels may be unsaturated
enough to allow for sufficient cold pool strengthening to support
increasing potential for strong to severe winds along an
accelerating gust front. If this occurs, areas across and east of
the Rio Grande River, particularly near and east through south of
Eagle Pass, will be increasingly impacted through 04-06Z.
..Kerr.. 06/01/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...
LAT...LON 29340052 29269978 28529910 27379957 27360021 27840101
28350144 28570112 29340052SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 31, 7:17 PM CDT | Severe Thunderstorm Watch | SPC | Dimmit, Edwards, Kinney, Maverick, Real, Uvalde and 2 more | 8 hr |
| Jun 1, 12:09 AM CDT | Severe Thunderstorm Watch | SPC | Brooks, Duval, Jim Hogg, Jim Wells, La Salle, McMullen and 2 more | 6 hr |
| Jun 1, 12:44 AM CDT | Mesoscale Discussion | SPC | Dimmit, La Salle, Maverick, Zavala | 91 min |
| Jun 1, 2:50 AM CDT | Mesoscale Discussion | SPC | La Salle, McMullen, Webb | 85 min |
| Jun 1, 2:14 PM CDT | Mesoscale Discussion | SPC | Dallam, Hartley | 2 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.