Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Fri Apr 17 2026
Valid 180100Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
ILLINOIS INTO NORTHEAST MISSOURI...AND OVER NORTHERN OKLAHOMA...
...SUMMARY...
Damaging storms producing wind, hail and isolated tornadoes remain
possible this evening from Illinois into Oklahoma.
...WI/MI into IL and MO...
Supercells have largely merged into a broken line of assorted bows
from far southeast WI across much of northern into western IL and
trailing into northeast MO. The 00Z ILX sounding shows steep lapse
rates aloft and large deep-layer shear, as well as veering winds
with height. Low-level SRH will remain favorable for rotation to
develop at least briefly anywhere within the line, with damaging
winds the most likely threat. Storms have recently become better
organized over central MO, and this activity may affect the St.
Louis area later tonight. For lower MI into northern IN, the
organized line of storms to the west along with a 60 kt low-level
jet suggest at least isolated severe gusts may occur overnight
despite lesser instability.
For more information about Illinois, see mesoscale discussion 484.
...OK...Southeast KS...southwest MO...northwest AR...
Scattered severe cells persist near and north of the cold front
across much of northern OK and extending into southeast KS. Although
the undercutting cold air will likely mitigate wind potential, steep
lapse rates aloft along with ample deep-layer shear will continue to
favor hail. Storm coverage may be more isolated into southwest OK
later tonight, but the environment remains quite favorable for large
hail.
One corridor for possible damaging wind or even a tornado is over
northeast OK into southwest MO. Here, the front is not surging as
fast, and storms over Osage county are already oriented more
favorably N-S relative to the deep-layer shear. A southwest
low-level jet near 50 kt will further support low-level rotation.
..Jewell.. 04/18/2026
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