Alert archive / Texas / Mesoscale Discussions in 2021
Mesoscale Discussion 595
The Storm Prediction Center issued this mesoscale discussion at May 11, 2021, 4:37 PM CDT for Beauregard Parish, Calcasieu Parish, Louisiana; 14 counties in Texas. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- May 11, 2021, 4:37 PM CDT (21:37 UTC)
- Expired
- May 11, 2021, 6:00 PM CDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 164
Counties Beauregard Parish, LA, Calcasieu Parish, LA, Angelina County, TX, Grimes County, TX, Hardin County, TX, Houston County, TX, Jasper County, TX, Liberty County, TX, Montgomery County, TX, Newton County, TX, Orange County, TX, Polk County, TX, San Jacinto County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX
The radar
The Houston radar (KHGX), 145 km from the middle of the area, began a volume at 21:40 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
Lake Charles Mun, LA (KLCH), launched 12:00Z, 9.6 hours before the alert went out and 163 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
- 2925 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 472 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 87 m²/s²
- 0-3 km storm-relative helicity
- 155 m²/s²
- Significant tornado parameter
- 1.8
- Supercell composite
- 11.9
The text
As transmitted.
529
ACUS11 KWNS 112137
SWOMCD
SPC MCD 112137
LAZ000-TXZ000-112300-
Mesoscale Discussion 0595
NWS Storm Prediction Center Norman OK
0437 PM CDT Tue May 11 2021
Areas affected...East-central Texas and far southwest Louisiana
Concerning...Severe Thunderstorm Watch 164...
Valid 112137Z - 112300Z
The severe weather threat for Severe Thunderstorm Watch 164
continues.
SUMMARY...Severe storms in east-central Texas may move out of watch
164 in the next few hours.
DISCUSSION...The strongest storms within watch 164 are moving into
Trinity county, Texas at 2130Z. The environment downstream of this
ongoing activity remains favorable with 1500 to 2000 J/kg MLCAPE and
effective shear around 35 to 40 knots per SPC mesoanalysis. In
addition, this activity is located near a warm frontal boundary.
Locally backed winds near this boundary are increasing low-level
SRH. The KPOE VWP can be used as a proxy for this low-level shear
profile and it is showing 0-1 SRH in excess of 200 m2/s2 and flow
around 2km has increased to around 45 knots. Therefore, a localized
tornado threat will exist near this warm front over the next few
hours as these storms move across east-central Texas.
In addition, given the favorable downstream environment, this
activity may persist east of watch 164 and a downstream watch may be
needed across portions of southeast Texas and southwest Louisiana.
..Bentley/Hart.. 05/11/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LCH...SHV...HGX...
LAT...LON 31479526 31369401 30959318 30169330 29969401 30259552
30389592 30689616 31479526SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 5:22 PM CDT | Severe Thunderstorm Watch | SPC | Allen, Beauregard, Vernon | 4 hr |
| May 11, 6:36 PM CDT | Mesoscale Discussion | SPC | Beauregard, Vernon | 84 min |
| 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, 1:59 PM CDT | Mesoscale Discussion | SPC | Anderson, Bell, Burleson, Burnet, Cherokee, Coryell and 18 more | 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, 5:23 PM CDT | Mesoscale Discussion | SPC | Atascosa, Bee, Colorado, DeWitt, Goliad, Gonzales and 11 more | 2 hr |
Nearby
Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Louisiana, 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.