ACUS11 KWNS 141756
SWOMCD
SPC MCD 141756
WIZ000-ILZ000-IAZ000-MNZ000-142000-

Mesoscale Discussion 0419
NWS Storm Prediction Center Norman OK
1256 PM CDT Tue Apr 14 2026

Areas affected...Parts of central/eastern IA...southern WI...and
northern IL

Concerning...Severe potential...Tornado Watch likely

Valid 141756Z - 142000Z

Probability of Watch Issuance...95 percent

SUMMARY...The risk of supercells capable of producing several
tornadoes (some strong to intense), giant hail, and severe wind
gusts will increase by around 19-22Z. A tornado watch is likely
within the next couple hours.

DISCUSSION...The latest surface analysis depicts a quasi-stationary
boundary extending from central/northern IA into southern/central
WI, with an additional composite outflow boundary farther south from
northeast IA into northern IL. Over the next few hours, continued
diurnal heating of a moist air mass (upper 60s dewpoints) should
erode remaining inhibition at the base a substantial EML, resulting
in the development of strong surface-based buoyancy (upwards of
3000-3500 J/kg MLCAPE). As this occurs, initial thunderstorm
development is expected across parts of central/eastern IA near the
intersecting boundaries by around 19-22Z -- aided by a subtle
frontal wave tracking eastward along the quasi-stationary boundary.

The strongly unstable air mass coupled with 40-50 kt of effective
shear will favor rapid thunderstorm organization/intensification
into semi-discrete supercells and organized clusters. Initially,
very large to giant hail (2-3+ inches in diameter) and severe wind
gusts will be the main concern with potentially splitting supercells
-- given a mostly straight hodograph. However, a south-southwesterly
low-level jet will strengthen across the area later this afternoon
into the evening and likely favor a transition to dominant
right-moving supercells with a quickly increasing tornado risk. The
strong buoyancy and 200-300+ m2/s2 effective SRH will support strong
to intense tornadoes with any longer-lived supercells, along with a
continued risk of giant hail and severe gusts. Eventually,
thunderstorms may have a tendency of growing upscale into clusters
with eastward extent, which will yield an increasing risk of
damaging wind swaths.

A tornado watch will be issued within the next couple hours.

..Weinman/Gleason.. 04/14/2026

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

ATTN...WFO...LOT...MKX...DVN...ARX...DMX...

LAT...LON   41219309 41419361 41849390 42349386 42679350 43349177
            43819045 43798943 43548877 42948850 42438870 41938916
            41309166 41219309

MOST PROBABLE PEAK TORNADO INTENSITY...120-150 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...2.75-4.25 IN