Mesoscale Discussion 339

Issued

Apr 9, 2021, 9:49 AM CDT (14:49 UTC)

Expired

Apr 9, 2021, 11:45 AM CDT

In force

116 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

60%

The Dallas/Ft Worth radar (KFWS), 189 km from the middle of the area, began a volume at 14:50 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.

• Severe Thunderstorm Watch 76Apr 9, 12:05 PM CDT

406 
ACUS11 KWNS 091449
SWOMCD
SPC MCD 091449 
LAZ000-ARZ000-TXZ000-OKZ000-091645-

Mesoscale Discussion 0339
NWS Storm Prediction Center Norman OK
0949 AM CDT Fri Apr 09 2021

Areas affected...Parts of northeast Texas...southeastern
Oklahoma...southwestern Arkansas and northwestern Louisiana

Concerning...Severe potential...Watch possible 

Valid 091449Z - 091645Z

Probability of Watch Issuance...60 percent

SUMMARY...Intensifying, strong to severe thunderstorm development is
possible across the Ark-La-Tex vicinity by early afternoon,
including increasing potential for large, damaging hail, locally
strong surface gusts and perhaps a tornado or two.  A severe weather
watch probably will be needed at some point, perhaps by around Noon,
possibly sooner.

DISCUSSION...Thunderstorm activity has initiated near the Red River,
northeast of the Dallas-Fort Worth Metroplex.  This appears
associated with moistening and destabilization above the capping
elevated mixed-layer air, aided by forcing for ascent beneath the
left exit region of an approaching high-level jet of lower-latitude
Pacific origin.  CAPE supporting this convection is initially weak,
but activity is occurring above a broader area of lower/mid
tropospheric warm advection, with southerly low-level level moisture
return ongoing near the storms, eastward toward the Ark-La-Tex.  

As lift associated with warm advection continues, various model
output suggests that mid-level capping will continue to erode,
allowing for storm development supported by inflow of moist parcels
characterized by moderate to large CAPE.  Shear through the
cloud-bearing layer will also become larger and the potential for
severe hail will probably increase.  Gradually, activity may become
increasingly rooted in a destabilizing boundary layer across
northeastern Texas into the Ark-La-Tex vicinity toward 18-19Z.  As
this occurs, severe weather threat likely will increase, with the
evolution of supercell structures possible, accompanied by the
potential to produce large, damaging hail, locally damaging wind
gusts and a risk for a tornado.

..Kerr/Thompson.. 04/09/2021

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

LAT...LON   34359748 35059644 34649497 34129346 32899322 31979406
            32319552 32919669 33079726 34359748

Mesoscale Discussions in Texas, 2021Mesoscale Discussions in Oklahoma, 2021Mesoscale Discussions in Arkansas, 2021Every mesoscale discussion in 2021

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.