spc ac 121727
day 2 convective outlook
nws storm prediction center norman ok
1227 pm cdt sun apr 12 2026
valid 131200z - 141200z
...there is an enhanced risk of severe thunderstorms across portions
of central/eastern minnesota into western/central wisconsin...
...summary...
severe thunderstorms are likely across the upper mississippi valley
and great lakes region with potential for large to very large hail,
damaging wind, and tornadoes. a more conditional and isolated risk
for severe storms is possible across portions of the southern plains
on monday.
...synopsis...
a southwesterly flow regime will continue from the southern plains
to the upper midwest on monday. low-amplitude upper ridging will
move across the upper midwest during the day ahead of a shortwave
trough moving across the northern plains. the shortwave will shift
east across the great lakes overnight. meanwhile, an upper trough
from the northern rockies to offshore the southern ca coast will
pivot eastward toward the four corners region. at the surface, low
pressure near the sd/ne border will develop east along the mn/ia
border to central wi. lee troughing will persist across the plains.
a dryline will extend southwest from the mid-mo valley into western
ok/tx, while a warm front extends from southern mn into
southern/central wi. these boundaries will become a focus for severe
thunderstorm development during the afternoon/evening.
...upper midwest...
along and south of the surface warm front across mn into
southern/central wi, strong daytime heating will be occurring amid
dew points in the low to mid 60s. this will yield moderate to strong
instability with mlcape around 2000-3000 j/kg. a plume of steep low
to mid-level lapse rates will also impinge upon the region through
the afternoon. capping will likely suppress thunderstorm activity
for much of the day as the shortwave upper ridge moves across the
region. by the late afternoon/early evening, a shortwave trough will
overspread the region with an increase in the low-level jet.
thunderstorm activity is expected to develop, with initially
elevated supercells likely given strong deep layer shear and
thermodynamic profiles. these will be capable of large to very large
hail (some 2-3+ inches in diameter). should any supercells be able
to anchor to the warm front and become surface based, the threat for
a tornado or two (possibly strong) will increase given large
clockwise curved hodographs indicative of favorable low-level shear.
an enhanced risk was included with this outlook driven by the hail
potential. convection will spread eastward with time into mi,
continuing to pose a risk for hail overnight.
...central/southern plains....
a conditional severe risk will extend further down the dryline into
the central/southern plains for the afternoon/evening. strong
daytime heating will yield very warm temperatures ahead of the
dryline but most convective temperatures are near or exceeding 90f.
forecast soundings indicate strong capping in place across much of
the region through the afternoon with generally weak forcing for
ascent outside of the dryline circulation, which will likely inhibit
a more widespread severe risk. nonetheless, moderate to strong
instability will overlap increasing deep layer shear as the
low-level jet increases through the evening. an isolated supercell
threat will be possible along the dryline, with greater confidence
along the red river in northern tx/southwestern ok and further south
into texas near the rio grande valley. should supercells develop,
the main risk will be for large to very large hail (some 2+ inches
in diameter).
..thornton.. 04/12/2026
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note: the next day 2 outlook is scheduled by 0600z