Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 679
The Storm Prediction Center issued this mesoscale discussion at May 18, 2021, 6:13 PM CDT for 20 counties in Texas. It was in force for 92 min.
The area
The outline as issued.
The facts
- Issued
- May 18, 2021, 6:13 PM CDT (23:13 UTC)
- Expired
- May 18, 2021, 7:45 PM CDT
- In force
- 92 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 188
Counties Austin County, TX, Brazos County, TX, Burleson County, TX, Colorado County, TX, DeWitt County, TX, Fayette County, TX, Freestone County, TX, Gonzales County, TX, Grimes County, TX, Houston County, TX, Karnes County, TX, Lavaca County, TX, Lee County, TX, Leon County, TX, Madison County, TX, Robertson County, TX, Walker County, TX, Waller County, TX, Washington County, TX, Wilson County, TX
The radar
The Austin/San Antonio radar (KEWX), 98 km from the middle of the area, began a volume at 23:18 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 12:00Z, 11.2 hours before the alert went out and 231 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
- 12 J/kg
- Mixed-layer CIN
- -595 J/kg
- Mixed-layer LCL
- 1962 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- -66 m²/s²
- 0-3 km storm-relative helicity
- -43 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.7
The text
As transmitted.
006
ACUS11 KWNS 182313
SWOMCD
SPC MCD 182313
TXZ000-190045-
Mesoscale Discussion 0679
NWS Storm Prediction Center Norman OK
0613 PM CDT Tue May 18 2021
Areas affected...Portions of central into eastern TX
Concerning...Tornado Watch 188...
Valid 182313Z - 190045Z
The severe weather threat for Tornado Watch 188 continues.
SUMMARY...The severe threat will continue into this evening, with a
primary threat of locally damaging wind, though isolated hail and a
tornado or two remain possible.
DISCUSSION...At 23Z, extensive convection is ongoing from central
into eastern TX, generally near and north of an outflow-reinforced
surface boundary that is expected to continue sagging slowly
southward this evening. The primary threat is likely to be locally
damaging wind, as continued cell mergers and outflow consolidation
may support small bowing clusters within the larger convective
plume. Transient supercell structures remain possible though, with
convective elements within the warm sector deepening as they
approach the surface boundary. Any such supercells would pose some
risk of hail, and perhaps a brief tornado as they interact with the
boundary.
With some increase in the low-level jet expected later this evening,
a more extensive MCS may develop and begin propagating eastward,
with a continued threat of locally damaging wind and perhaps a
tornado or two.
..Dean.. 05/18/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...SHV...HGX...FWD...CRP...EWX...
LAT...LON 29019851 29759739 30749699 31809645 31579519 30779516
29479626 29059669 28789715 28719753 28779838 29019851SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 17, 7:04 PM CDT | Mesoscale Discussion | SPC | Archer, Bosque, Brown, Clay, Comanche, Eastland and 15 more | 86 min |
| May 17, 7:23 PM CDT | Mesoscale Discussion | SPC | Carson, Dallam, Gray, Hansford, Hartley, Hemphill and 8 more | 2 hr |
| May 17, 7:32 PM CDT | Tornado Watch | SPC | Brown, Callahan, Coke, Coleman, Concho, McCulloch and 4 more | 3 hr |
| May 17, 7:37 PM CDT | Mesoscale Discussion | SPC | Callahan, Coke, Coleman, Glasscock, Howard, Jones and 6 more | 83 min |
| May 17, 8:04 PM CDT | Severe Thunderstorm Watch | SPC | Archer, Clay, Comanche, Eastland, Erath, Hamilton and 11 more | 5 hr |
| May 17, 8:34 PM CDT | Mesoscale Discussion | SPC | Atascosa, Dimmit, Frio, La Salle, McMullen, Maverick and 2 more | 116 min |
| May 17, 9:28 PM CDT | Mesoscale Discussion | SPC | Carson, Collingsworth, Donley, Gray, Hansford, Hemphill and 7 more | 2 hr |
| May 17, 9:44 PM CDT | Mesoscale Discussion | SPC | Armstrong, Borden, Briscoe, Childress, Collingsworth, Cottle and 15 more | 91 min |
| May 17, 10:23 PM CDT | Mesoscale Discussion | SPC | Archer, Brown, Callahan, Clay, Coke, Coleman and 16 more | 97 min |
| May 17, 10:35 PM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Brewster, Crane, Crockett, Dawson and 13 more | 85 min |
| May 17, 10:58 PM CDT | Severe Thunderstorm Watch | SPC | Andrews, Borden, Brown, Coke, Coleman, Concho and 22 more | 7 hr |
| May 17, 11:37 PM CDT | Mesoscale Discussion | SPC | Bosque, Brown, Comanche, Denton, Eastland, Erath and 9 more | 83 min |
| May 18, 1:02 AM CDT | Mesoscale Discussion | SPC | Brooks, Duval, Jim Hogg | 58 min |
| May 18, 1:29 AM CDT | Mesoscale Discussion | SPC | Coke, Concho, Crane, Crockett, Ector, Glasscock and 13 more | 91 min |
| May 18, 5:07 AM CDT | Mesoscale Discussion | SPC | Coke, Concho, Irion, Reagan, Runnels, Schleicher and 2 more | 53 min |
| May 18, 1:18 PM CDT | Mesoscale Discussion | SPC | Atascosa, Austin, Bastrop, Bexar, Brazos, Burleson and 28 more | 117 min |
| May 18, 1:57 PM CDT | Mesoscale Discussion | SPC | Bailey, Castro, Deaf Smith, Parmer, Randall, Swisher | 3 hr |
| May 18, 2:29 PM CDT | Tornado Watch | SPC | Anderson, Atascosa, Austin, Bastrop, Bexar, Blanco and 30 more | 7 hr |
| May 18, 2:30 PM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Cherokee, Franklin, Gregg and 12 more | 2 hr |
| May 18, 3:51 PM CDT | Severe Thunderstorm Watch | SPC | Bowie, Camp, Cass, Cherokee, Franklin, Gregg and 11 more | 5 hr |
| May 18, 3:52 PM CDT | Mesoscale Discussion | SPC | Bastrop, Caldwell, Colorado, Fayette, Gonzales, Guadalupe and 2 more | 83 min |
| May 18, 5:10 PM CDT | Mesoscale Discussion | SPC | La Salle, McMullen, Webb | 95 min |
| May 18, 5:39 PM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Gregg, Harrison, Marion, Morris and 1 more | 2 hr |
| May 18, 6:07 PM CDT | Mesoscale Discussion | SPC | Armstrong, Borden, Briscoe, Carson, Castro, Cochran and 17 more | 113 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.