Mesoscale Discussion 324

Issued

Apr 7, 2021, 2:22 PM CDT (19:22 UTC)

Expired

Apr 7, 2021, 3:15 PM CDT

In force

53 min

Issued by

the Storm Prediction Center

Concerning

Tornado watch 75

The Shreveport radar (KSHV), 119 km from the middle of the area, began a volume at 19:25 UTC, the scan nearest the moment this went out.

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161 
ACUS11 KWNS 071922
SWOMCD
SPC MCD 071922 
ARZ000-MOZ000-LAZ000-TXZ000-OKZ000-072015-

Mesoscale Discussion 0324
NWS Storm Prediction Center Norman OK
0222 PM CDT Wed Apr 07 2021

Areas affected...much of Arkansas...far southeastern
Oklahoma...northeastern Texas...and northwestern Louisiana

Concerning...Tornado Watch 75...

Valid 071922Z - 072015Z

The severe weather threat for Tornado Watch 75 continues.

SUMMARY...The severe threat continues across WW 75.

DISCUSSION...A mix of linear and cellular convective cells continue
to gradually deepen along a front that now extends from near FYV to
FSM to PRX to south of TPL in northeast Texas.  The storms are in a
weakly capped environment, with most of the ascent tied to the
advancing front, although cells over the open warm sector are also
maturing.  The storms are in a favorable environment for
organization given 30-40 knots of deep shear and modest mid-level
lapse rates supporting 1000-1750 J/kg MLCAPE.  Low-level shear
supports rotation, locally enhancing the risk for hail and tornadoes
near dominant convection.  The greatest severe threat over the next
couple hours may evolve near convection that can strengthen nearer
the warmer surface temperatures from Louisiana into southeastern
Arkansas.

Farther southwest, convection may pose an isolated damaging-wind
risk from Anderson to Robertson Counties in Texas along the front. 
Surface temperatures just ahead of these storms have warmed into the
low 80s, supporting stronger buoyancy (near 2000 J/kg MLCAPE) though
low-level shear profiles are a bit weaker compared to areas just to
the east.  It appears unlikely that a new WW or local extension will
be needed in these areas due to the isolated nature of the threat,
though trends will be monitored as the front continues to migrate
southward in that area.

..Cook/Hart.. 04/07/2021

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

ATTN...WFO...PAH...MEG...JAN...LZK...SGF...LCH...SHV...TSA...
HGX...FWD...

LAT...LON   34369477 35319444 36569388 36879324 36819157 36379074
            35159078 33419134 32119191 31309231 30969330 30929469
            30809589 30979656 31469662 32569579 33109542 34369477

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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.