658
ACUS11 KWNS 292100
SWOMCD
SPC MCD 292100
MNZ000-IAZ000-NEZ000-SDZ000-292330-

Mesoscale Discussion 1385
NWS Storm Prediction Center Norman OK
0400 PM CDT Mon Jun 29 2026

Areas affected...Eastern South Dakota...Southwest
Minnesota...Northeast Nebraska...and far Northwest Iowa

Concerning...Severe potential...Watch possible

Valid 292100Z - 292330Z

Probability of Watch Issuance...60 percent

SUMMARY...Surface-based storm initiation will become increasingly
likely in the 22-00Z time frame. Large to very large hail in excess
of 2 inches and damaging winds with significant gusts of 75+ mph
will be the predominant hazards. Observational data are being
monitored for a possible watch issuance.

DISCUSSION...The 18Z OAX sounding sampled a pronounced cap at the
base of an EML, which has inhibited convective development along a
cold front moving into the area from the west. However, latest CAM
guidance suggests that isolated thunderstorm development is possible
by as early as 22Z, but more likely closer to 00Z as continued
daytime heating and the glancing influence of a short-wave trough to
the west, locally erode the cap. Latest objective analysis indicates
the air mass is strongly unstable with MLCAPE as high as 3000-4500+
J/kg. When coupled with 35-45 kt deep-layer shear, the setup appears
supportive of supercells as the initial storm mode with the
potential for large to very large hail.

Later this evening into tonight, storms may begin to coalesce on
growing cold pools, leading to a subsequent increase in damaging
wind potential with significant gusts of 75+ mph possible. The
greatest potential for a tornado or two will exist across eastern SD
into western MN; however, the tendency for the low-level wind field
to veer ahead of the cold front is expected to limit the overall
threat.

..Mead/Guyer.. 06/29/2026

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

ATTN...WFO...MPX...FSD...OAX...ABR...

LAT...LON   42189807 43649782 44639769 45179779 45349675 45269584
            43429592 42509638 41889769 42189807

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN