Mesoscale Discussion 2056
NWS Storm Prediction Center Norman OK
0531 PM CDT Thu Aug 20 2026
Areas affected...portions of central into southwestern Minnesota and
far eastern South Dakota
Concerning...Severe potential...Watch possible
Valid 202231Z - 210030Z
Probability of Watch Issuance...60 percent
SUMMARY...The risk for severe hail will increase through the evening
hours as storms gradually develop through the evening. A few severe
gusts and a tornado or two may also occur. Timing of storm
development is uncertain, but convective trends will be closely
monitored for the need of a WW issuance.
DISCUSSION...A few discrete storms have developed and sustained
themselves along a surface trough over northern MN, where MRMS MESH
depicts some hail potentially falling with these storms. As the
surface trough continues to move southeast, storms should gradually
increase in coverage and intensity, especially after 0Z. Surface
temperatures approaching 80 F, amid mid 60s F dewpoints and 7-8 C/km
boundary-layer lapse rates, is yielding over 2000 J/kg MLCAPE.
Furthermore, increased southwesterly 850 mb flow beneath modest 500
mb westerlies is contributing to 40 kts of effective bulk shear,
especially over central and southern MN. Currently, the MPX VAD
shows a modestly curved and elongated hodograph, supportive of
supercell structures. The current thinking is that any storm that
can mature and sustain itself in this environment will become
supercellular, accompanied by a severe hail threat (some potentially
exceeding 2 inches in diameter). A few severe gusts may also occur,
and given the appreciable low-level hodograph, a tornado or two
cannot be rule out either.
Visible satellite shows an overall lack of agitated CU, with several
billow clouds remaining (indicative of some residual stability). It
is thus unclear when convective initiation and the subsequent need
for a WW issuance will occur. Given the favorable ambient
environment though, convective trends will be closely monitored.
..Squitieri/Guyer.. 08/20/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DLH...MPX...FGF...FSD...ABR...
LAT...LON 43719738 45259588 46249498 46669442 46899402 46919341
46689310 46059276 45309267 44639294 44129357 43669477
43429560 43389667 43719738
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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