Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 570
The Storm Prediction Center issued this mesoscale discussion at May 9, 2021, 1:41 PM CDT for 33 counties in Texas. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- May 9, 2021, 1:41 PM CDT (18:41 UTC)
- Expired
- May 9, 2021, 3:15 PM CDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...severe thunderstorm watch likely
- Chance of a watch
- 80%
All 33 counties
Anderson County, TX, Bell County, TX, Blanco County, TX, Brazos County, TX, Burleson County, TX, Burnet County, TX, Coryell County, TX, Ellis County, TX, Falls County, TX, Freestone County, TX, Gillespie County, TX, Grimes County, TX, Hays County, TX, Henderson County, TX, Hill County, TX, Houston County, TX, Kaufman County, TX, Lampasas County, TX, Lee County, TX, Leon County, TX, Limestone County, TX, Llano County, TX, Madison County, TX, Mason County, TX, McLennan County, TX, Milam County, TX, Navarro County, TX, Robertson County, TX, San Saba County, TX, Travis County, TX, Van Zandt County, TX, Walker County, TX, Williamson County, TX
The radar
The Ft Hood radar (KGRK), 63 km from the middle of the area, began a volume at 18:42 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, 6.7 hours before the alert went out and 172 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
- 1448 J/kg
- Mixed-layer CIN
- -333 J/kg
- Mixed-layer LCL
- 846 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 473 m²/s²
- 0-3 km storm-relative helicity
- 499 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.8
The text
As transmitted.
247
ACUS11 KWNS 091842
SWOMCD
SPC MCD 091841
TXZ000-092015-
Mesoscale Discussion 0570
NWS Storm Prediction Center Norman OK
0141 PM CDT Sun May 09 2021
Areas affected...Portions of central/north TX
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 091841Z - 092015Z
Probability of Watch Issuance...80 percent
SUMMARY...The severe thunderstorm threat will increase with time
this afternoon, with a few supercells possible. Very large hail will
be the primary threat, with locally severe wind gusts also possible.
Watch issuance is likely by 20Z.
DISCUSSION...At 1830Z, a cold front is moving southeastward across
parts of central/north TX. A plume of elevated convection is noted
just east of the front, with gradually deepening cumulus noted along
the front itself. As the cap continues to erode this afternoon,
scattered surface-based storms are expected to develop along the
front, and may also possibly evolve from the plume of elevated
convection to the east. Steep midlevel lapse rates are supporting
moderate-to-strong buoyancy across the region, with MLCAPE of
2000-3000 J/kg along/east of the front per recent objective
mesoanalyses. While low-level flow is expected to gradually weaken
across the area with time, midlevel flow will remain relatively
strong, supporting effective shear of 40-50 kt.
As surface-based storms mature this afternoon, a few supercells are
likely to develop, with a threat of very large hail. Locally severe
wind gusts will also be possible, especially with any upscale
growing clusters that may evolve with time. Severe thunderstorm
watch issuance is likely by 20Z.
..Dean/Thompson.. 05/09/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...FWD...EWX...SJT...
LAT...LON 30939933 31599815 32449667 32869598 32759576 32129561
31609547 30629519 30069751 29979861 30339929 30559936
30939933SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 9, 12:14 PM CDT | Mesoscale Discussion | SPC | Anderson, Bowie, Camp, Cass, Cherokee, Franklin and 22 more | 91 min |
| May 9, 1:14 PM CDT | Severe Thunderstorm Watch | SPC | Angelina, Bowie, Camp, Cass, Cherokee, Franklin and 14 more | 8 hr |
| May 9, 3:01 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Bell, Blanco, Bosque, Burnet, Comal and 32 more | 7 hr |
| May 9, 3:42 PM CDT | Mesoscale Discussion | SPC | Bowie, Cass, Harrison, Marion, Morris | 93 min |
| May 9, 5:41 PM CDT | Mesoscale Discussion | SPC | Angelina, Cass, Harrison, Marion, Nacogdoches, Panola and 4 more | 2 hr |
| May 9, 5:45 PM CDT | Severe Thunderstorm Watch | SPC | Jasper, Newton, Tyler | 7 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.