352
ACUS11 KWNS 250909
SWOMCD
SPC MCD 250909
MIZ000-WIZ000-ILZ000-251045-

Mesoscale Discussion 1404
NWS Storm Prediction Center Norman OK
0409 AM CDT Tue Jun 25 2024

Areas affected...East-Central/Southern WI...Far Northern
IL...Western Lower MI

Concerning...Severe Thunderstorm Watch 455...

Valid 250909Z - 251045Z

The severe weather threat for Severe Thunderstorm Watch 455
continues.

SUMMARY...Threat for severe gusts continues across southeast WI,
with large hail more likely across far western Lower MI. Additional
development is occurring across southwest WI and convective trends
are being monitored for possible watch across southern WI and
northern IL.

DISCUSSION...Ongoing MCS has accelerated notably over the past hour
or so, with storm motion now closer to 55 kt. The MCS has trended
towards a more southerly motion as well, favoring now north-south
oriented instability gradient. This more southerly motion may limit
the chance that this MCS fully crosses Lake Michigan, with the
strongest portion of the MCS potentially tracking closer to the
southwestern shore of the lake. Strong gusts have started reaching
the surface, with gusts of 55, 53 and 50 kt recently observed at
SBM, GRB, and MTW, respectively. Potential for strong gusts is
expected to persist within the line for at least the next few hours.

Farther southwest, new thunderstorm development has occurred in the
IA/WI/IL border intersection vicinity, within the core of the
southwesterly low-level jet extending across the region. There
appears to be some potential for additional development in southern
WI, which would fill in the gap between these storms and the ongoing
MCS. This scenario is uncertain, but could lead to am additional
severe threat across southern WI and northern IL. As a result,
convective trends are being monitored closely.

Thunderstorms continue to intensify within the warm-air advection
wing that is now over far western Lower MI. Primary threat with
these storms is large hail, but a strong gust or two is possible as
well.

..Mosier/Edwards.. 06/25/2024

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

ATTN...WFO...APX...GRR...GRB...LOT...MKX...DVN...ARX...

LAT...LON   42919078 44978796 44568574 43048531 42458690 41978959
            42919078