Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 445
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 1:38 AM CDT for 16 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2021, 1:38 AM CDT (06:38 UTC)
- Expired
- Apr 28, 2021, 3:45 AM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 115
Counties Callahan County, TX, Coke County, TX, Coleman County, TX, Eastland County, TX, Glasscock County, TX, Jones County, TX, Mitchell County, TX, Nolan County, TX, Palo Pinto County, TX, Reagan County, TX, Runnels County, TX, Shackelford County, TX, Stephens County, TX, Sterling County, TX, Taylor County, TX, Upton County, TX
The radar
The San Angelo radar (KSJT), 69 km from the middle of the area, began a volume at 06:39 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
Midland Regional, TX (KMAF), launched 00:00Z, 6.6 hours before the alert went out and 157 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
- 18 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 3768 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 41 m²/s²
- 0-3 km storm-relative helicity
- 32 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
699
ACUS11 KWNS 280638
SWOMCD
SPC MCD 280638
TXZ000-280845-
Mesoscale Discussion 0445
NWS Storm Prediction Center Norman OK
0138 AM CDT Wed Apr 28 2021
Areas affected...parts of western Texas
Concerning...Severe Thunderstorm Watch 115...
Valid 280638Z - 280845Z
The severe weather threat for Severe Thunderstorm Watch 115
continues.
SUMMARY...Severe storms over southwest Texas are likely to persist,
and may increase in intensity in a few hours over parts of northwest
Texas. Damaging winds, large hail, and eventually a tornado risk are
possible.
DISCUSSION...Surface analysis shows an outflow boundary (nearly
stationary) from west of GLE to near ABI, with fresh outflow moving
across Sterling/Reagan/Upton Counties. Area VWPs indicate a strong
low-level jet which will aid air-mass recovery over northwest TX
later tonight.
A zone of greater surface theta-e currently extends from near ABI
southwestward through SJT and DRT, with 68-70 F dewpoints. With
time, ongoing cells west of ABI may incorporate the more unstable
air mass, especially if the pre-existing outflow boundary begins to
lift north. The strong deep-layer shear will continue to favor
fast-moving cells or bows capable of damaging wind and hail. Greater
effective SRH on the warm side of the outflow boundary could support
a tornado risk, with 300+ m2/s2 present. Given currently observed
storm motions, cells may move into the better air even if the
boundary remains stationary.
..Jewell.. 04/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...SJT...MAF...
LAT...LON 31460235 32050149 32450100 32770002 33109877 32899830
32359833 31829889 31640004 31380128 31270192 31280228
31460235SPC 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, 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, 5:41 PM CDT | Mesoscale Discussion | SPC | Bandera, Bexar, Frio, Kendall, Kinney, Maverick and 4 more | 2 hr |
| 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.