spc ac 271721
day 2 convective outlook
nws storm prediction center norman ok
1221 pm cdt sat jun 27 2026
valid 281200z - 291200z
...there is a slight risk of severe thunderstorms across portions of
the dakotas into northern minnesota...
...summary...
severe thunderstorms are possible from the northern plains into
parts of the upper midwest on sunday. large to very large hail and
severe winds are the primary hazards.
...northern plains/upper midwest...
a challenging forecast scenario is expected on sunday across
portions of the dakotas into the upper midwest. upper ridging is
expected to amplify over the mid/upper ms valley and western great
lakes vicinity. this will result in capping concerns across the
region owing to height rises and warming aloft, especially from the
eastern dakotas into the upper midwest. however, surface troughing
will sharpen and extend southward across the central dakotas into
the central plains. meanwhile, a warm front/moisture gradient will
extend southeastward from northern mn into wi and the southern lake
michigan vicinity. overnight, a surface low is forecast to mildly
deepen somewhere from western ne into sd. forecast guidance
continues to show uncertainty in the evolution of this feature.
southeasterly low-level flow will transport rich boundary layer
moisture westward across the region, with dewpoints in the mid 60s
to near 70 f common. a plume of steep midlevel lapse rates will
overspread the red river and upper ms valley during the day, while
lapse rates further west steepen during the evening/overnight. this
will result in corridors of moderate to strong instability within
the warm sector to the east of the surface trough and south of the
warm front. however, given the building upper ridge, capping may
persist across the region, limiting potential for surface-based
convection.
storms are expected to be ongoing sunday morning across the eastern
dakotas and will spread east through the day. while this activity
may be elevated, large hail is possible. a southerly low-level jet
is expected to persist through the daytime, and if storms can become
near-surface based, some damaging wind potential also would exist.
it is unclear how far east this convection may persist as it crests
the building upper ridge.
overnight, convection is expected to develop near the surface
low/trough on the leading edge of a strong southerly low-level jet
across western or central sd. this activity may be elevated, but
will likely initially be supercell mode with an attendant risk for
large to very large hail. if convection grows upscale, some wind
risk is also possible, but this is more uncertain given capping
concerns.
...southern mid-atlantic...
an mcv is expected to move across the nc vicinity on sunday. ahead
of this feature, a seasonally very moist and moderately unstable
airmass will be in place. deep-layer flow will be modest, but the
mcv may locally enhance vertical shear and provide support for a
band of forward propagating convection moving off the higher terrain
during the after and early evening. sporadic strong/damaging wind
gusts will be possible with these storms.
...southern plains...
a dryline will be oriented from western ks into southwest tx sunday
afternoon/evening. strong heating is expected along the boundary
along with sufficient dryline convergence. deep boundary
circulations and a narrow corridor of moderate instability will
support isolated storm development. strong downburst/outflow winds
will be possible with these storms as generally weak vertical shear
limits stronger updrafts longevity/organization.
..leitman.. 06/27/2026
click to get wuus02 ptsdy2 product
note: the next day 2 outlook is scheduled by 0600z