Mesoscale Discussion 321

Issued

Apr 7, 2021, 10:18 AM CDT (15:18 UTC)

Expired

Apr 7, 2021, 12:15 PM CDT

In force

117 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch likely

Chance of a watch

80%

The Springfield radar (KSGF), 95 km from the middle of the area, began a volume at 15:20 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

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• Severe Thunderstorm Watch 74Apr 7, 12:00 PM CDT
• Tornado Watch 75Apr 7, 12:40 PM CDT

762 
ACUS11 KWNS 071518
SWOMCD
SPC MCD 071518 
MOZ000-ARZ000-KSZ000-071715-

Mesoscale Discussion 0321
NWS Storm Prediction Center Norman OK
1018 AM CDT Wed Apr 07 2021

Areas affected...Parts of western/central Missouri and adjacent
portions of eastern Kansas...northeastern Oklahoma and northwestern
Arkansas

Concerning...Severe potential...Watch likely 

Valid 071518Z - 071715Z

Probability of Watch Issuance...80 percent

SUMMARY...The initiation of strong to severe thunderstorm
development appears possible by early this afternoon.  A severe
weather watch likely will be needed at some point, perhaps as early
as Noon-1 PM CDT.

DISCUSSION...In the wake of an initial weakening mid-level
perturbation and associated thunderstorm development, the primary
upstream short wave impulse is in the process of pivoting eastward
across western Kansas/Oklahoma and northwest Texas, and forecast to
gradually take on a neutral to negative tilt across the central
Great Plains through 18-20Z.  Between these two mid-level features,
an area of enhanced lower/mid tropospheric warm advection may be
contributing to renewed thunderstorm development near/above a
remnant outflow boundary across the Lake of the Ozarks vicinity. 
There appears at least some potential for this activity to intensify
through mid day, while spreading northeastward through central
Missouri, perhaps aided by inflow emanating from a destabilizing
boundary layer to the southwest.  In the presence of at least modest
cloud-bearing layer and shear, and steepening mid-level lapse rates,
this may be accompanied by a risk for severe hail.

However, the primary concern appears to be the potential for the
initiation of vigorous thunderstorms within a corridor of
strengthening deep-layer forcing for ascent, just ahead of the
eastward advancing cold front approaching the western
Missouri/Arkansas border vicinity.  While it appears possible that
this may occur as far north as areas near/northeast of the cold
front/outflow boundary intersection (currently south of Kansas
City), more substantive warm sector boundary-layer warming may
remain confined to  areas south through southeast of the Lake of the
Ozarks.

While the timing of this new thunderstorm development could wait
until a bit later this afternoon, it appears possible as early as
17-18Z.  Once this occurs, wind profiles including 30-50+ kt flow in
the 850-500 mb layer, and modestly large and clockwise curved
low-level hodographs, in the presence of mixed-layer CAPE in excess
of 1000 J/kg, will be conducive to organized severe thunderstorm
development.  This includes the potential evolution of supercell
structures capable of producing severe hail and, gradually,
increasing risk for damaging wind gusts and perhaps a couple of
tornadoes.

..Kerr/Hart.. 04/07/2021

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

ATTN...WFO...LSX...LZK...SGF...EAX...TSA...

LAT...LON   35839440 37629452 38129480 39229492 39789479 39689376
            39429286 39379208 38669157 37319239 35999333 35839440

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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.