Mesoscale Discussion 328

Issued

Apr 7, 2021, 5:12 PM CDT (22:12 UTC)

Expired

Apr 7, 2021, 7:15 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

60%

The Jackson/Brandon,MS radar (KDGX), 139 km from the middle of the area, began a volume at 22:13 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.

858 
ACUS11 KWNS 072212
SWOMCD
SPC MCD 072212 
TNZ000-MSZ000-MOZ000-ARZ000-LAZ000-TXZ000-080015-

Mesoscale Discussion 0328
NWS Storm Prediction Center Norman OK
0512 PM CDT Wed Apr 07 2021

Areas affected...Portions of eastern AR...the MO Bootheel...western
TN...northern/central/western MS...and northeastern/central LA

Concerning...Severe potential...Watch possible 

Valid 072212Z - 080015Z

Probability of Watch Issuance...60 percent

SUMMARY...A threat for isolated severe thunderstorms capable of
producing mainly damaging winds and perhaps a few tornadoes may
develop eastward this evening. Watch issuance is possible for parts
of this area in the next couple of hours.

DISCUSSION...A rash of low-level warm advection driven convection
has developed this afternoon across central/eastern AR and northern
LA.  With the exception of northwestern LA, recent radar trends
suggest much of this activity is struggling to substantially
intensify as it moves east-northeastward. Surface dewpoints in
western TN and vicinity drop quickly into the low/mid 50s, with
gradually decreasing instability with eastward extent. Furthermore,
the VWP from KNQA shows limited veering in the boundary layer, which
may tend to limit potential for low-level rotation. Farther south
into northern/central/western MS and northeastern/central LA,
greater moisture is present and stronger diurnal heating has
occurred. Latest mesoanalysis estimates suggest up to 1000-1500 J/kg
of MLCAPE exists across this region, and sufficient deep-layer shear
should support organized updrafts. If storms can congeal into a
better defined line ahead of the surface cold front, then the
damaging wind threat would increase this evening. A few tornadoes
also appear possible if storms can remain semi-discrete. This
tornado potential may be slightly greater across
northeastern/central LA into MS. Overall, the potential for a more
substantial severe threat developing this evening remains unclear
owing to the poorly organized convection across AR at the moment.
Trends will continue to be monitored, and a watch may eventually be
needed for parts of this region.

..Gleason/Grams.. 04/07/2021

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

ATTN...WFO...MEG...JAN...LIX...LCH...SHV...

LAT...LON   32848902 31379032 30929111 30539251 30619384 31019429
            31539217 32169182 32849184 33519106 34059071 34769091
            36049073 36259041 36308948 36298820 35688811 34988822
            33718849 32848902

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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.