Alert archive / Texas / Mesoscale Discussions in 2021

Mesoscale Discussion 379

April 13, 2021De Soto Parish, Louisiana; 4 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 13, 2021, 3:43 PM CDT for De Soto Parish, Louisiana; 4 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 13, 2021, 3:43 PM CDT (20:43 UTC)
Expired
Apr 13, 2021, 5:45 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
20%

Counties De Soto Parish, LA, Cherokee County, TX, Houston County, TX, Nacogdoches County, TX, Shelby County, TX

The radar

The Shreveport radar (KSHV), 125 km from the middle of the area, began a volume at 20:47 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 12:00Z, 8.7 hours before the alert went out and 134 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 12:00Z on 2021-04-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 12:00Z on 2021-04-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 0 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1548 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
0 m²/s²
0-3 km storm-relative helicity
28 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

336 
ACUS11 KWNS 132043
SWOMCD
SPC MCD 132043 
LAZ000-TXZ000-132245-

Mesoscale Discussion 0379
NWS Storm Prediction Center Norman OK
0343 PM CDT Tue Apr 13 2021

Areas affected...East-central Texas and west-central Louisiana

Concerning...Severe potential...Watch unlikely 

Valid 132043Z - 132245Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated large hail and damaging wind gusts are possible
as a storm or two develops in east-central Texas. The threat will be
limited by weak upper-level forcing and should subside as surface
heating ceases. No watch is anticipated this afternoon.

DISCUSSION...Towering cumulus have developed along the stalled front
near OCH. While low to mid 80s F temperatures and upper 60s to low
70s F dewpoints have supported around 2000 J/kg MLCAPE, residual
capping around 700 mb has kept updraft development/maturation muted
thus far. Continued heating may support a diurnally-driven threat
for large hail and damaging wind gusts, given 35 kts of effective
shear and steep low-level lapse rates. Storm coverage will likely
remain isolated on account weak upper-level forcing as well as
eventual loss of surface heating after sunset. No watch is
anticipated for this activity.

..Wendt/Thompson.. 04/13/2021

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

ATTN...WFO...SHV...HGX...FWD...

LAT...LON   31469581 31809548 32019479 32219394 32189351 31769340
            31349425 31179526 31229566 31469581

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 13, 8:28 AM CDTMesoscale DiscussionSPCAcadia, Allen, Ascension, Assumption, Avoyelles, East Baton Rouge and 11 more2 hr
Apr 13, 11:43 AM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, Iberia, Iberville, Jefferson and 16 more2 hr
Apr 13, 12:06 PM CDTSevere Thunderstorm WatchSPCAscension, Assumption, Iberia, Iberville, Jefferson, Lafourche and 10 more6 hr
Apr 13, 2:44 PM CDTMesoscale DiscussionSPCIberia, Jefferson, Lafourche, Plaquemines, St. Mary, Terrebonne and 1 more2 hr
Apr 12, 9:26 PM CDTMesoscale DiscussionSPCBurnet, Concho, Edwards, Gillespie, Kerr, Kimble and 10 more64 min
Apr 12, 10:41 PM CDTMesoscale DiscussionSPCCallahan, Fisher, Jones, Nolan, Palo Pinto, Shackelford and 4 more2 hr
Apr 13, 4:37 PM CDTMesoscale DiscussionSPCAndrews, Archer, Baylor, Borden, Clay, Coke and 28 more2 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.