Mesoscale Discussion 1876
NWS Storm Prediction Center Norman OK
0438 AM CDT Sun Aug 09 2026
Areas affected...parts of southern Minnesota...northern Iowa
Concerning...Severe potential...Watch unlikely
Valid 090938Z - 091245Z
Probability of Watch Issuance...20 percent
SUMMARY...Increasing, intensifying thunderstorm development appears
probable near and north of the Minnesota/Iowa border vicinity
through 6-8 AM CDT. This may be accompanied by a period of
increasing potential for severe hail, then, perhaps, increasing
potential for strong to severe surface gusts. It is possible that
this could eventually require a severe weather watch, though it is
not yet clear that this will be needed in the near term.
DISCUSSION...Downstream of stronger lingering convection developing
southeastward near/northeast of the Huron SD vicinity, models have
been suggesting that forcing for ascent associated with the subtle
digging short wave perturbation may increasingly couple with lift
driven by warm advection/convergence on the nose of a lingering
30-40 kt nocturnally strengthened southerly low-level jet. By
11-13Z, it appears this will become focused near/north of the
Minnesota/Iowa border vicinity, where a corridor of increasing
moisture return above at least a shallow stable boundary-layer is
likely to contribute to increasingly sizable CAPE, in the presence
of strengthening cloud-bearing layer shear.
As this occurs, a more notable increase and intensification of
thunderstorm activity appears possible, perhaps accompanied by at
least a period of increasing potential for severe hail. Subsequent
upscale growth might eventually organize and become accompanied by
increasing risk for damaging wind gusts, though if/how soon this
occurs after daybreak remains unclear.
..Kerr/Smith.. 08/09/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ARX...MPX...DMX...FSD...
LAT...LON 44119609 44689403 43679158 42849301 43069395 43299587
44119609
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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