Mesoscale Discussion 1889

Issued

Oct 24, 2021, 2:40 PM CDT (19:40 UTC)

Expired

Oct 24, 2021, 4:15 PM CDT

In force

95 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...tornado watch likely

Chance of a watch

80%

The Western Arkansas radar (KSRX), 34 km from the middle of the area, began a volume at 19:45 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.

• Tornado Watch 532Oct 24, 3:45 PM CDT

737 
ACUS11 KWNS 241940
SWOMCD
SPC MCD 241940 
ARZ000-OKZ000-242115-

Mesoscale Discussion 1889
NWS Storm Prediction Center Norman OK
0240 PM CDT Sun Oct 24 2021

Areas affected...Portions of eastern OK and western/northern AR

Concerning...Severe potential...Tornado Watch likely 

Valid 241940Z - 242115Z

Probability of Watch Issuance...80 percent

SUMMARY...Storms capable of producing large hail, damaging winds,
and a few tornadoes should develop this afternoon. Tornado Watch
issuance will likely be needed.

DISCUSSION...Even with broken cloud cover remaining over eastern OK
and western AR this afternoon, the low levels continue to gradually
destabilize with filtered diurnal heating and low-level moistening.
An 18Z sounding from SGF in southern MO showed a residual cap just
below 700 mb. But, with stronger heating to the south in OK/AR,
latest mesoanalysis shows boundary-layer convective inhibition has
mostly eroded. Storms will likely develop along or just ahead of a
surface cold front by 21-22Z (4-5 PM CDT) across northeastern OK and
northwestern AR. Around 1500-2000 J/kg of MLCAPE will be present
across the warm sector to sustain intense convection. Even though
the strongest mid-level winds associated with a low-amplitude
shortwave trough may tend to be displaced just to the north of this
region, around 30-40 kt of deep-layer shear should prove adequate
for storm organization.

A mix of supercells and multicells is expected this afternoon and
evening, posing a threat for both large hail and damaging wind
gusts. Low-level south-southwesterly winds are not forecast to be
overly strong across eastern OK and western/northern OK. Still,
around 100-200 m2/s2 of effective SRH should be enough for some
low-level rotation with any supercell. There will probably be some
tendency for storms to congeal into one or more line segments with
eastward extent into AR this evening, with a greater threat for
damaging winds. But, embedded tornadic circulations will remain
possible within the broken line. A Tornado Watch will likely be
needed by 4 PM CDT to address the increasing severe threat across
this region.

..Gleason/Thompson.. 10/24/2021

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

ATTN...WFO...LZK...SHV...TSA...

LAT...LON   36989467 36459464 36469225 36479114 35259203 33979381
            33959449 34119515 34589564 35319591 36099569 36989467

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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.