Storm Prediction Center Mesoscale Discussion 1366

   Mesoscale Discussion 1366
   NWS Storm Prediction Center Norman OK
   1014 AM CDT Sun Jun 28 2026

   Areas affected...parts of Central into Eastern Iowa into northwest
   Illinois

   Concerning...Severe potential...Watch possible 

   Valid 281514Z - 281715Z

   Probability of Watch Issuance...40 percent

   SUMMARY...Convective trends are being monitored for a possible
   increase in damaging wind potential by late morning into early
   afternoon. A Severe Thunderstorm Watch is possible.

   DISCUSSION...On the southern flank of a long-lived MCS, a more
   intense storm has recently developed near Ames, IA, within a
   pronounced low-level warm advection pattern, per KDMX VWP.
   Mesoanalysis suggests that the storm is located in close proximity
   to a stationary front that extends southeast through southeast IA
   into central IL. The air mass south of the boundary is very moist
   with the presence of steep mid-level lapse rates yielding a
   moderately unstable environment with MLCAPE upwards of 2000 J/kg. 

   The main uncertainty is whether the current storms will become fully
   rooted within the boundary layer given the expected strengthening of
   the cap at the base of an EML through the day. The 12Z CAMs offer
   various scenarios with regard to convective evolution this morning
   but by afternoon largely agree that the strengthening cap will
   become prohibitive to surface-based storm development. However, in
   the event this more recent storm development can establish a cold
   pool, the background environment appears supportive of damaging wind
   potential in addition to some large hail threat.

   ..Mead/Guyer.. 06/28/2026

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

   ATTN...WFO...DVN...ARX...DMX...

   LAT...LON   42179345 42759297 42889227 42338988 41938972 41598995
               41359034 41329113 41679241 42179345 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN