spc ac 261731
day 2 convective outlook
nws storm prediction center norman ok
1231 pm cdt sun apr 26 2026
valid 271200z - 281200z
...there is an enhanced risk of severe thunderstorms across portions
of the middle mississippi valley into western indiana...western
kentucky...and northwestern tennessee...
...summary...
widespread strong to severe thunderstorm development appears
probable across the middle mississippi into lower ohio valleys
monday afternoon through monday evening, accompanied by potential
for a few strong tornadoes, damaging wind gusts and large hail.
...discussion...
a potent shortwave will move across the mid-mississippi valley into
the ohio valley/great lakes on monday, with strong mid-level flow
over spreading the region. as a result, a surface low will deepen
across the central plains and move eastward into northern
missouri/southern iowa, with attendant cold front shifting south and
east and northward lifting warm front. a dryline will be in place
ahead of the approaching cold front from western missouri southward
into south into eastern oklahoma. this will eventually be overtaken
by the cold front.
convection will likely be ongoing at the start of the monday period,
with a remnant mcs moving across central missouri and spurious
convection to the north across iowa. additional thunderstorm
development in the afternoon will be highly conditional on the track
and maintenance of this morning mcs. nonetheless, it appears that
severe storms will develop by the afternoon along and ahead of the
cold front and in the vicinity of the lifting warm front with the
primary risks for large to very large hail, tornadoes (a few of
which may be strong), and an eventual evolution to potential for
damaging winds towards the late afternoon/evening.
...middle mississippi into lower ohio valleys...
the morning convection across northern missouri into iowa makes for
complex forecast monday afternoon. initially, the morning mcs and
spurious convection to the north may pose a low wind/hail risk. once
this shifts eastward, uncertainty remains in how the air mass will
evolve into the afternoon. guidance seems to suggest that strong
daytime heating, albeit somewhat filtered through mid-level cloud
debris, will occur with air mass recovery across missouri into
southern iowa. the strengthening low-level jet will usher in a plume
of steep low to mid-level lapse rates and upper 60's dew points.
confidence is highest in a better corridor of
heating/destabilization across central/southern missouri into
central illinois. as such, hail and tornado probabilities were
shifted south and west. initial supercells in this region will be
capable of large to very large hail (some 2-3+ inches in diameter)
and tornadoes (perhaps some strong).
a more conditional threat exists further north across northern
missouri into southern iowa near the lifting warm front. a warm
front will lift northward with reinforcement from remnant outflow
producing a zone of differential heating. should better heating and
recovery be able to occur in this region, potential for supercells
with large to very large hail (some 2-3 inches in diameter) and
strong tornadoes will be possible.
as the cold front shifts southward, mode will become more mixed and
linear with time, with an increase in the damaging wind risk.
however, line embedded circulations will may continue to pose a risk
for strong tornadoes, with evolving meso-vortices along developing
gust fronts of convective outflow. this will extend into central
illinois, western kentucky, and western tennessee into the late
evening.
..thornton.. 04/26/2026
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