ACUS11 KWNS 100114
SWOMCD
SPC MCD 100114
INZ000-ILZ000-WIZ000-IAZ000-100315-

Mesoscale Discussion 1886
NWS Storm Prediction Center Norman OK
0814 PM CDT Sun Aug 09 2026

Areas affected...eastern Iowa into northern Illinois

Concerning...Severe potential...Severe Thunderstorm Watch likely

Valid 100114Z - 100315Z

Probability of Watch Issuance...80 percent

SUMMARY...Supercells are likely to develop across eastern Iowa into
northern Illinois this evening. Primary threat will be for large
hail and damaging wind.

DISCUSSION...A southwesterly low-level jet (LLJ) around 30-35 kts
will move into portions of northern Illinois this evening. A surface
boundary extends across northern Illinois. Near the boundary and
the nose of the LLJ, there is good run to run agreement in CAM
guidance that storms will develop across some portion of far eastern
Iowa into northern Illinois within the warm advection regime this
evening. Some radar returns and cloud cooling have been noted in the
last 30 minutes across this area. The environment across this region
is strongly unstable, with MLCAPE around 2000-4000 J/kg sampled by
00z RAOBs from DVN and ILX. Deep layer shear around 35-40 kts will
increase with the LLJ later this evening. This regime will support
supercells with the primary threat of large hail and damaging wind.
For any supercell that can remain rooted in the surface, a tornado
will be possible. A watch will likely be needed to cover this
potential in the next couple of hours.

..Thornton/Mosier.. 08/10/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!6ZPe9v2WxWFv6sLOywdptZmQiJXiXmUs8teowASS63ITpmmYMMGq0rm7Lrs9MlKBIGmf0M4ZIDuk3MgiS5vfkhVn60s$ for graphic product...

ATTN...WFO...LOT...ILX...MKX...DVN...

LAT...LON 40499156 41529139 42199070 42478996 42538906 42528832
42258779 41988732 41768725 41238754 40598858 40408979
40479114 40499156

MOST PROBABLE PEAK TORNADO INTENSITY...85-110 MPH
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


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