Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 144

February 28, 20216 counties in Arkansas; 9 parishes in Louisiana; 12 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2021, 9:01 PM CST for 6 counties in Arkansas; 9 parishes in Louisiana; 12 counties in Texas. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued
Feb 28, 2021, 9:01 PM CST (03:01 UTC)
Expired
Feb 28, 2021, 10:30 PM CST
In force
89 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 14
All 27 counties

Columbia County, AR, Hempstead County, AR, Lafayette County, AR, Miller County, AR, Nevada County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Lincoln Parish, LA, Red River Parish, LA, Union Parish, LA, Webster Parish, LA, Bowie County, TX, Cass County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX, Smith County, TX, Upshur County, TX

The radar

The Shreveport radar (KSHV), 18 km from the middle of the area, began a volume at 03:02 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

Shreveport, LA (KSHV), launched 00:00Z, 3.0 hours before the alert went out and 24 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-pSkew-T log-p diagram, Shreveport, LA at 00:00Z on 2021-03-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1289 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Shreveport, LA at 00:00Z on 2021-03-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 203 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
1289 J/kg
Mixed-layer CIN
-30 J/kg
Mixed-layer LCL
813 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
203 m²/s²
0-3 km storm-relative helicity
213 m²/s²
Significant tornado parameter
1.9
Supercell composite
7.9

Open this sounding in Storm Lab

The text

As transmitted.

244 
ACUS11 KWNS 010302
SWOMCD
SPC MCD 010301 
LAZ000-ARZ000-TXZ000-010430-

Mesoscale Discussion 0144
NWS Storm Prediction Center Norman OK
0901 PM CST Sun Feb 28 2021

Areas affected...Arklatex

Concerning...Severe Thunderstorm Watch 14...

Valid 010301Z - 010430Z

The severe weather threat for Severe Thunderstorm Watch 14
continues.

SUMMARY...An isolated severe threat may continue for a couple more
hours across parts of the Arklatex. A tornado along with wind damage
and hail will be possible. An extension in time may be needed after
the expiration at 04Z.

DISCUSSION...Radar imagery shows a line of storms ongoing from far
northeast Texas into far northwestern Louisiana, where some cells
are semi-discrete. The Shreveport WSR-88D VWP shows some directional
shear in the boundary layer with 0-3 km storm relative helicity near
325 m2/s2. This may support an isolated tornado threat with the
stronger cells in the short-term. Isolated large hail and wind
damage will also be possible. The threat may become more isolated as
the front moves to the southeast and undercuts the ongoing storms.
However, a lingering severe threat could require an extension in
time for WW 14.

..Broyles/Grams.. 03/01/2021

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

ATTN...WFO...JAN...LZK...SHV...HGX...FWD...

LAT...LON   31279436 31429452 31509485 31469493 31459510 31639527
            31719537 31879546 32119545 32429546 32649566 32689561
            32609523 32559514 32969516 32929468 33289466 33329471
            33669474 33539428 33579391 33609386 33749397 33789387
            33989381 33919342 33829324 33729305 33429308 33399257
            33169212 32829202 32669216 32619240 32529240 32519249
            32479272 32159282 32159309 31949313 31929331 31919345
            31829344 31849385 31659382 31639414 31609436 31279436

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 28, 6:27 PM CSTMesoscale DiscussionSPCArkansas, Bradley, Calhoun, Clark, Cleveland, Crittenden and 12 more93 min

Nearby

Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Arkansas, 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.