Mesoscale Discussion 320

Issued

Apr 7, 2021, 6:40 AM CDT (11:40 UTC)

Expired

Apr 7, 2021, 8:45 AM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

5%

The Springfield radar (KSGF), 79 km from the middle of the area, began a volume at 11:44 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

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032 
ACUS11 KWNS 071140
SWOMCD
SPC MCD 071140 
MOZ000-ARZ000-OKZ000-071345-

Mesoscale Discussion 0320
NWS Storm Prediction Center Norman OK
0640 AM CDT Wed Apr 07 2021

Areas affected...portions of central/southwestern MO...eastern OK
and northwestern AR.

Concerning...Severe potential...Watch unlikely 

Valid 071140Z - 071345Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated severe hail and strong gusts are possible from
thunderstorms over this region until shortly after sunrise.  The
threat appears too disorganized and marginal for a watch in the near
term, though conditions will become more favorable over parts of
this region later today.

DISCUSSION...11Z surface mesoanalysis shows an elongated low-
pressure area along a frontal zone arching from near OMA-EMP.  A
cold front was drawn from there across south-central OK and
west-central TX.  An outflow boundary was drawn ahead of the front,
over north-central MO between CDJ-IRK and southwestward between
CNU-IDP, where it is being overtaken by the front. 

Widely scattered showers and a few thunderstorms have formed ahead
of the cold front -- both near the outflow boundary and to its south
across the western Ozarks region.  Some development is possible
along the front and southern limb of the outflow boundary in the
next few hours, before the more-substantial severe threat ramps up
around late morning into midday (per upcoming convective outlook). 
The main area of lift supporting convection in the meantime,
however, should continue to be in the zone of warm advection and
moisture transport close to the axis of a 45-55-kt south-
southwesterly LLJ, with parcels being lifted isentropically to LFC. 
Modified forecast soundings indicate a corridor of 1500-2000 J/kg
MUCAPE along and west of the LLJ axis.  Initially modest effective-
shear magnitudes in the 25-35-kt range will limit organization of
most of the convection, though deep shear will increase with time
through the morning.  Given the elevated nature of the convection
and the marginal shear in the meantime, however, hail coverage and
size should remain marginal.  A few strong gusts also may penetrate
the near-surface stable layer.  A watch is not anticipated for the
short-fused scenario.

..Edwards.. 04/07/2021

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

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

LAT...LON   35169508 37589425 38829242 38039164 36009315 35149404
            35169508

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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.