Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0230 PM CDT Thu Jul 17 2025

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ROUGHLY FROM IOWA
INTO ILLINOIS AND INDIANA...

...SUMMARY...
Corridors of strong to severe storms are expected from the northern
and central High Plains to the Mid-Mississippi and Lower Ohio
Valleys on Saturday.

...IA/IL/IN...
Model QPF differences aside, the overarching theme is for a large
area of strong instability to develop near a stalled front from
southern IA/northern MO into IL and IN Saturday afternoon with mid
70s F dewpoints. This will exist beneath the southern fringe of
perhaps 40 kt west/northwest midlevel flow, and the combination of
strong instability and favorable deep-layer mean winds will favor
corridors of severe storms with damaging winds. Shear may also favor
severe hail, and even a few supercells given such large CAPE over
IA/IL/IN. The risk area will likely be adjusted in subsequent
outlook cycles as the event nears.

...High Plains...
Modest westerly midlevel flow of 30-40 kt will exist over the
northern High Plains, ahead of a broad upper trough over the Pacific
Northwest/northern Rockies. Cool midlevel temperatures will also
exist, steepening lapse rates. Strong heating is likely within a
surface trough from eastern MT southward across the High Plains,
with a ribbon of 1500-2000 J/kg MUCAPE wrapping northwestward around
a MN surface high. Cells capable of hail and localized severe gusts
will be possible, and a severe MCS is not out of the question
overnight into ND as the low-level jet increases. Greater
probabilities may be required in later updates.

..Jewell.. 07/17/2025