spc ac 131921
day 3 convective outlook
nws storm prediction center norman ok
0221 pm cdt mon apr 13 2026
valid 151200z - 161200z
...there is a slight risk of severe thunderstorms portion of the
southern plains into southern wisconsin...
...summary...
severe thunderstorms posing a risk for large hail and strong wind
gusts will be possible across portions of the southern plains toward
the great lakes on wednesday afternoon and evening.
...synopsis...
the upper-level trough will move eastward from the plains into the
upper midwest on wednesday, with continued enhanced west to
southwesterly flow across the southern plains into the great lakes
region. the surface dryline will remain in a similar location from
tuesday, extending across western oklahoma into southwestern and
western texas. a surface low will shift eastward across ia into wi,
with a cold front shifting south and east through the period.
scattered thunderstorm development is expected from the southern
plains into the upper midwest along the aforementioned boundaries
wednesday afternoon and evening.
...southern plains to great lakes...
widely scattered showers and thunderstorms will be ongoing at the
start of the period at 12z wednesday across much of the slight risk
region. a secondary round of thunderstorm development is likely to
occur near and ahead of the dryline extending from west texas into
western oklahoma wednesday afternoon. it remains somewhat uncertain
how morning convection will evolve and what the resulting effect on
the thermodynamic environment will be. most guidance suggests that
in the area ahead of the dryline across central ok to the red river
in northern texas will develop at least moderate instability
(1000-2000 j/kg of mlcape). deep layer shear profiles will remain
strong favoring supercells as the primary mode. the main threat will
be for large to very large hail and damaging wind, given linearly
elongated hodographs and weaker low-level shear.
thunderstorms are also expected to re-develop further north across
the central plains into the great lakes region along the
dryline/cold front intersection. a messy mode with mix of supercells
and multi-cell clusters is likely given the eventual southward
moving cold front. similarly, the main risks will be for damaging
wind and large hail across these regions.
...northeast...
shower and thunderstorm activity is expected to develop along and
south of a diffuse frontal boundary across the great lakes into
southern ny/northern pa. modestly unstable profiles, steepening
lapse rates, and strong deep layer shear will allow for some
isolated severe storm risk. primary risk would be for damaging wind
and small hail, though, a tornado could be possible near the
boundary.
..thornton.. 04/13/2026
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note: the next day 3 outlook is scheduled by 0730z