Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 594
The Storm Prediction Center issued this mesoscale discussion at May 11, 2021, 1:59 PM CDT for 24 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 11, 2021, 1:59 PM CDT (18:59 UTC)
- Expired
- May 11, 2021, 4:00 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 24 counties
Anderson County, TX, Bell County, TX, Burleson County, TX, Burnet County, TX, Cherokee County, TX, Coryell County, TX, Falls County, TX, Freestone County, TX, Henderson County, TX, Houston County, TX, Lee County, TX, Leon County, TX, Limestone County, TX, Madison County, TX, McLennan County, TX, Milam County, TX, Nacogdoches County, TX, Navarro County, TX, Robertson County, TX, Rusk County, TX, Smith County, TX, Travis County, TX, Trinity County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 95 km from the middle of the area, began a volume at 19:00 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, 7.0 hours before the alert went out and 186 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 521 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 177 m²/s²
- 0-3 km storm-relative helicity
- 215 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 4.0
The text
As transmitted.
586
ACUS11 KWNS 111900
SWOMCD
SPC MCD 111859
TXZ000-112100-
Mesoscale Discussion 0594
NWS Storm Prediction Center Norman OK
0159 PM CDT Tue May 11 2021
Areas affected...Parts of central into eastern Texas
Concerning...Severe potential...Watch possible
Valid 111859Z - 112100Z
Probability of Watch Issuance...40 percent
SUMMARY...There appears potential for an evolving cluster of
thunderstorms to become better organized and posing increasing risk
for damaging wind gusts by 4-5 PM CDT, if not before.
DISCUSSION...The bulk of increasingly widespread convection
approaching the Interstate 35 into Interstates 20/30 corridors of
central into northeast Texas remains rooted above a cool/stable
surface-based layer. However, across and north of the upper Texas
coastal plain, daytime heating is contributing to erosion of the
shallow leading edge of this air mass, with isolated storms now
initiating along the front, north of College Station and Huntsville.
Beneath steep mid-level lapse rates, boundary-layer moisture,
characterized by lower 70s F surface dewpoints, advecting northward
across and above the cool surface-based air is contributing to
sizable CAPE on the order of 2000-3000 J/kg. As inflow of this air
continues, further intensification of storms along the front is
possible. Eventually this activity may merge into the approaching
upstream convection, which may also begin to intensify as it
encounters increasing inflow of this unstable air.
Although flow in the lower through mid-levels is rather modest in
strength, deep-layer shear, beneath 50-70 kt westerly flow around
300 mb, could eventually contribute to organizing convection which
might pose increasing risk for potentially damaging wind gusts by
21-22Z, if not earlier.
..Kerr/Thompson.. 05/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...SHV...HGX...FWD...EWX...
LAT...LON 31889726 32249610 32509453 31419434 30839572 30699634
30079712 30239797 30749832 31399781 31889726SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 10, 8:01 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bexar, Dimmit, Frio, Kendall, Medina and 1 more | 119 min |
| May 11, 4:44 AM CDT | Mesoscale Discussion | SPC | Andrews, Borden, Coke, Crane, Crosby, Dawson and 26 more | 2 hr |
| May 11, 10:13 AM CDT | Mesoscale Discussion | SPC | Anderson, Bell, Bosque, Brown, Burnet, Callahan and 45 more | 62 min |
| May 11, 1:22 PM CDT | Mesoscale Discussion | SPC | Dimmit, Kinney, Maverick, Terrell, Val Verde, Zavala | 2 hr |
| May 11, 3:04 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Angelina, Brazos, Burleson, Cherokee, Freestone and 17 more | 4 hr |
| May 11, 3:41 PM CDT | Severe Thunderstorm Watch | SPC | Atascosa, Bandera, Bastrop, Bexar, Blanco, Caldwell and 29 more | 10 hr |
| May 11, 4:37 PM CDT | Mesoscale Discussion | SPC | Angelina, Grimes, Hardin, Houston, Jasper, Liberty and 8 more | 83 min |
| May 11, 5:22 PM CDT | Severe Thunderstorm Watch | SPC | Hardin, Jasper, Newton, Tyler | 4 hr |
| May 11, 5:23 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bee, Colorado, DeWitt, Goliad, Gonzales and 11 more | 2 hr |
| May 11, 6:36 PM CDT | Mesoscale Discussion | SPC | Hardin, Jasper, Newton, Polk, Tyler | 84 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.