Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 597

May 11, 2021Beauregard Parish, Vernon Parish, Louisiana; 5 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 11, 2021, 6:36 PM CDT for Beauregard Parish, Vernon Parish, Louisiana; 5 counties in Texas. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: May 11, 2021, 6:36 PM CDT (23:36 UTC)
Expired: May 11, 2021, 8:00 PM CDT
In force: 84 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 166

Counties Beauregard Parish, LA, Vernon Parish, LA, Hardin County, TX, Jasper County, TX, Newton County, TX, Polk County, TX, Tyler County, TX

The radar

The Lake Charles radar (KLCH), 94 km from the middle of the area, began a volume at 23:35 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 nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 12:00Z, 11.6 hours before the alert went out and 96 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

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

Open this sounding in Storm Lab

The text

As transmitted.

782 
ACUS11 KWNS 112336
SWOMCD
SPC MCD 112336 
LAZ000-TXZ000-120100-

Mesoscale Discussion 0597
NWS Storm Prediction Center Norman OK
0636 PM CDT Tue May 11 2021

Areas affected...Southeast Texas and southwest Louisiana

Concerning...Severe Thunderstorm Watch 166...

Valid 112336Z - 120100Z

The severe weather threat for Severe Thunderstorm Watch 166
continues.

SUMMARY...An organized line of storms is expected to maintain
intensity as it moves across southeast Texas and southwest Louisiana
over the past few hours. Large hail and damaging winds will be the
primary threat.

DISCUSSION...Storms have grown upscale into an organized line over
the past hour. Slow forward progression and mostly line parallel
low-level flow combined with weak modest DCAPE around 500 J/kg all
suggest the threat for widespread damaging winds is likely limited.
However, isolated wind damage where cores collapse may be possible.
In addition, isolated large hail has been observed with this
convection. The greater hail threat may be with supercells which
form ahead of the line and especially any left-split supercells such
as the one currently in Tyler county Texas at 2330Z. Line embedded
supercells and supercells forming ahead of this line may pose a
threat for a tornado or two given 0-1 SRH around 150 m2/s2 per KLCH
VWP. However, 2-3 km flow has weakened over the past hour which
likely limits a greater tornado threat.

..Bentley.. 05/11/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LCH...SHV...HGX...

LAT...LON   31329443 31229343 30989293 30529295 30269309 30139432
            30169468 30369521 31329443

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 11, 4:37 PM CDT	Mesoscale Discussion	SPC	Beauregard, Calcasieu	83 min
May 11, 5:22 PM CDT	Severe Thunderstorm Watch	SPC	Allen, Beauregard, Vernon	4 hr
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, 2021 Mesoscale Discussions in Louisiana, 2021 Every 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.