Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 412
The Storm Prediction Center issued this mesoscale discussion at Apr 23, 2021, 6:46 PM CDT for 25 counties in Texas. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Apr 23, 2021, 6:46 PM CDT (23:46 UTC)
- Expired
- Apr 23, 2021, 8:15 PM CDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 98
All 25 counties
Atascosa County, TX, Bell County, TX, Bexar County, TX, Blanco County, TX, Bosque County, TX, Burnet County, TX, Comal County, TX, Coryell County, TX, Erath County, TX, Frio County, TX, Guadalupe County, TX, Hamilton County, TX, Hays County, TX, Hood County, TX, Jack County, TX, Johnson County, TX, Kendall County, TX, Lampasas County, TX, Medina County, TX, Palo Pinto County, TX, Parker County, TX, Somervell County, TX, Tarrant County, TX, Travis County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 106 km from the middle of the area, began a volume at 23:46 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 12:00Z, 11.8 hours before the alert went out and 261 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
- 14 J/kg
- Mixed-layer CIN
- -89 J/kg
- Mixed-layer LCL
- 578 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- 397 m²/s²
- 0-3 km storm-relative helicity
- 249 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.3
The text
As transmitted.
632
ACUS11 KWNS 232346
SWOMCD
SPC MCD 232346
TXZ000-240115-
Mesoscale Discussion 0412
NWS Storm Prediction Center Norman OK
0646 PM CDT Fri Apr 23 2021
Areas affected...Areas near/west of I-35 corridor of central Texas
Concerning...Severe Thunderstorm Watch 98...
Valid 232346Z - 240115Z
The severe weather threat for Severe Thunderstorm Watch 98
continues.
SUMMARY...The potential for severe hail and wind is expected to
become more isolated with a decrease in storm coverage through 8-10
PM CDT. It is possible that parts of remaining valid portions of
Severe Thunderstorm Watch 98 could be replaced with a new severe
weather watch, but this is not certain.
DISCUSSION...Widely scattered strong to severe thunderstorm
development is ongoing west of the Interstate 35 corridor. This
activity initiated near the dryline, but moderate to strong
southwesterly deep-layer mean flow is aiding eastward advection
ahead of the eastward advancing surface boundary. North of the San
Antonio area, this is tending to spread into an environment
stabilized by prior convection. With the onset of boundary-layer
cooling along the dryline, inhibition beneath relatively warm
mid-level layers probably will begin to reduce convective coverage
in the absence of stronger deep-layer forcing for ascent.
The isolated cell south-southwest of San Antonio is developing into
locally moderate to strong instability characterized by CAPE up to
3000 J/kg. This activity might be slower to diminish, perhaps aided
by forcing associated with a subtropical jet speed maximum.
Otherwise, lift north/northeast of the weak triple-point low may
become a focus for a consolidating cluster of storms, near/south of
the Red River, to the northwest/north of the Dallas-Fort Worth
Metroplex through 01-03Z.
..Kerr.. 04/23/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FWD...CRP...EWX...SJT...
LAT...LON 29529931 30709846 31549833 32519860 33349838 32799703
30399747 28469846 28439958 29529931SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 23, 11:29 AM CDT | Mesoscale Discussion | SPC | Archer, Bastrop, Bell, Bexar, Blanco, Bosque and 52 more | 91 min |
| Apr 23, 12:37 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Archer, Bastrop, Bell, Blanco, Bosque and 53 more | 7 hr |
| Apr 23, 12:43 PM CDT | Mesoscale Discussion | SPC | Baylor, Childress, Collingsworth, Cottle, Foard, Hall and 2 more | 3 hr |
| Apr 23, 12:43 PM CDT | Mesoscale Discussion | SPC | Anderson, Angelina, Brazoria, Chambers, Cherokee, Fort Bend and 25 more | 2 hr |
| Apr 23, 2:00 PM CDT | Tornado Watch | SPC | Angelina, Austin, Brazos, Burleson, Chambers, Cherokee and 22 more | 7 hr |
| Apr 23, 3:14 PM CDT | Tornado Watch | SPC | Archer, Baylor, Childress, Clay, Collingsworth, Cottle and 7 more | 5 hr |
| Apr 23, 3:27 PM CDT | Mesoscale Discussion | SPC | Baylor, Foard, Hardeman, Wilbarger | 2 hr |
| Apr 23, 3:28 PM CDT | Mesoscale Discussion | SPC | Bosque, Brown, Comanche, Eastland, Erath, Hamilton and 11 more | 2 hr |
| Apr 23, 5:26 PM CDT | Mesoscale Discussion | SPC | Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more | 2 hr |
| Apr 23, 5:36 PM CDT | Mesoscale Discussion | SPC | Angelina, Houston, Jasper, Nacogdoches, Newton, Polk and 7 more | 54 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.