ACUS11 KWNS 210014
SWOMCD
SPC MCD 210013
IAZ000-MNZ000-SDZ000-NEZ000-210115-

Mesoscale Discussion 2059
NWS Storm Prediction Center Norman OK
0713 PM CDT Thu Aug 20 2026

Areas affected...portions of southeastern South Dakota to the
Nebraska and Iowa borders

Concerning...Severe potential...Watch possible

Valid 210013Z - 210115Z

Probability of Watch Issuance...40 percent

SUMMARY...An isolated severe hail threat will persist for a few more
hours. However, storms will move into stronger MLCINH, which may
limit the spatial and temporal extent of the severe threat.

DISCUSSION...Multiple splitting supercells have developed over the
last couple of hours, with an instance of golfball hail recently
reported on a storm in Minnehaha County, SD. These storms are
benefiting from 3000+ J/kg MLCAPE and 50 kts of effective bulk shear
in place. Nonetheless, these storms are also approaching a region of appreciable MLCINH. The current thinking is that these storms should
gradually weaken as they move off of the surface trough/boundary and
move into the inhibition. As such, while a few more instances of
severe hail could occur, the severe threat should remain confined
along the surface trough for just a few more hours.

..Squitieri/Guyer.. 08/21/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!9gf4xx6Y5zbAeJ4ckZhYXfXwAN6U68wCfBRT2pgkpy4NJCAQq6Eosc-dAf7-gScEjYHuQNbsCi4NBPXF9RwwHwk7kog$ for graphic product...

ATTN...WFO...FSD...OAX...LBF...

LAT...LON 42619823 42829877 42999891 43109886 43149818 43279774
43529727 43839692 43899669 43889644 43849622 43709612
43249616 42859627 42639654 42579705 42619823

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN


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