Subj : MESO: Mesoscale Discussion 1617
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jul 09 2025 18:34:12

ACUS11 KWNS 091832
SWOMCD
SPC MCD 091831=20
SDZ000-MTZ000-WYZ000-092030-

Mesoscale Discussion 1617
NWS Storm Prediction Center Norman OK
0131 PM CDT Wed Jul 09 2025

Areas affected...portions of western into central South Dakota

Concerning...Severe potential...Severe Thunderstorm Watch likely=20

Valid 091831Z - 092030Z

Probability of Watch Issuance...80 percent

SUMMARY...Scattered thunderstorm development appears imminent.
Storms should gradually intensify through the afternoon, accompanied
by a severe wind and hail threat. A Severe Thunderstorm Watch
issuance will be needed in the next few hours.

DISCUSSION...Visible satellite shows deepening CU along the Black
Hills in southwestern SD, where convective inhibition continues to
rapidly erode with boundary-layer heating/mixing. MLCAPE is already
reaching the 1500-2500 J/kg range ahead of the storms, with over 30
kts of effective bulk effective shear (and a straight hodograph)
already in place (per 18Z mesoanalysis/UNR special observed
sounding). Thunderstorms should develop shortly, and will soon after
move over the more unstable/sheared airmass. Current thinking is
that storms should remain more discrete for a few hours before
attempting to grow upscale. Given steep low-level lapse rates,
severe gusts are a concern (a few of which may exceed 75 mph), with
the 8-9 C/km 700-500 mb lapse rates and straight hodographs
supporting severe hail potential as well. A Severe Thunderstorm
Watch will eventually be needed to address the increasing severe
threat.

...Squitieri/Mosier.. 07/09/2025

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!9DOQTPnivZrFCyEBEYf4FocOZ-e86ABSgnR2ig-wxmER1v-MNgPuP2mzaW9ItMgWgV3Jenzco=
IP9yI1YKW99eVJD26c$  for graphic product...

ATTN...WFO...ABR...UNR...BYZ...

LAT...LON   43080277 43930359 45510441 45770433 45870371 45640180
            45120043 44360004 43700015 43270086 43000202 43080277=20

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


=3D =3D =3D
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