Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 465
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2021, 11:03 PM CDT for 43 counties in Texas. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2021, 11:03 PM CDT (04:03 UTC)
- Expired
- Apr 29, 2021, 1:00 AM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 121...122
All 43 counties
Atascosa County, TX, Bandera County, TX, Bastrop County, TX, Bell County, TX, Bexar County, TX, Blanco County, TX, Bosque County, TX, Burleson County, TX, Burnet County, TX, Caldwell County, TX, Collin County, TX, Comal County, TX, Coryell County, TX, Dallas County, TX, Ellis County, TX, Falls County, TX, Freestone County, TX, Gillespie County, TX, Gonzales County, TX, Guadalupe County, TX, Hamilton County, TX, Hays County, TX, Hill County, TX, Hood County, TX, Johnson County, TX, Kaufman County, TX, Kendall County, TX, Kerr County, TX, Lampasas County, TX, Lee County, TX, Limestone County, TX, Llano County, TX, McLennan County, TX, Medina County, TX, Milam County, TX, Navarro County, TX, Robertson County, TX, Rockwall County, TX, Somervell County, TX, Tarrant County, TX, Travis County, TX, Williamson County, TX, Wilson County, TX
The radar
The Ft Hood radar (KGRK), 34 km from the middle of the area, began a volume at 04:04 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
Fort Worth, TX (KFWD), launched 00:00Z, 4.1 hours before the alert went out and 241 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
- 1526 J/kg
- Mixed-layer CIN
- -11 J/kg
- Mixed-layer LCL
- 1058 m above ground
- 0-6 km bulk shear
- 73 kt
- 0-1 km storm-relative helicity
- 191 m²/s²
- 0-3 km storm-relative helicity
- 154 m²/s²
- Significant tornado parameter
- 2.2
- Supercell composite
- 9.4
The text
As transmitted.
897
ACUS11 KWNS 290404
SWOMCD
SPC MCD 290403
TXZ000-290600-
Mesoscale Discussion 0465
NWS Storm Prediction Center Norman OK
1103 PM CDT Wed Apr 28 2021
Areas affected...Centarl and Northeast Texas
Concerning...Tornado Watch 121...122...
Valid 290403Z - 290600Z
The severe weather threat for Tornado Watch 121, 122 continues.
SUMMARY...A severe threat is expected to continue into the early
overnight hours from the Texas Hill Country north-northeastward into
parts of northeast Texas. Large hail, wind damage and an isolated
tornado threat will be possible with the stronger thunderstorms.
DISCUSSION...The latest radar imagery from San Antonio and Fort
Worth shows several strong to severe thunderstorms located from
between Del Rio and San Antonio extending northward to near
Stephenville, Texas. The storms are located along and just to the
west of an inverted surface trough. The RAP shows an axis of
moderate instability near the surface trough with MLCAPE estimated
in the 2000 to 3000 J/kg range. WSR-88D VWPs near this axis of
instability have 0-6 km shear in the 55 to 65 kt range. The
instability and shear will likely keep the severe threat going late
this evening into the early overnight period. Large hail and wind
damage will be the primary threats with supercells that persist. An
isolated tornado threat may also exist with any supercell that is
dominant.
..Broyles.. 04/29/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...FWD...EWX...SJT...
LAT...LON 28729844 28899794 29499740 30539656 31239619 32739587
33279624 33249707 32749771 31649839 30319928 29379966
28869907 28729844SPC 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, 9:13 PM CDT | Mesoscale Discussion | SPC | Bastrop, Bexar, Caldwell, Colorado, Comal, Fayette and 4 more | 92 min |
| 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 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.