spc ac 261916
day 3 convective outlook
nws storm prediction center norman ok
0216 pm cdt fri jun 26 2026
valid 281200z - 291200z
...there is a slight risk of severe thunderstorms across portions of
north dakota and the upper midwest...
...summary...
severe thunderstorms are possible from the northern plains into
parts of the upper midwest on sunday. large hail and severe winds
are the primary hazards.
...synopsis...
the western u.s. upper trough will deepen and persist over that
region on sunday. meanwhile, upper ridging will intensify over the
midwest into the south, while a shortwave upper trough moves from
the ohio valley to the southern mid-atlantic region. at the surface,
some uncertainty persists with regards to the location of lee
surface low development in the central or northern plains. the nam
appears to be an outlier compared to the ecmwf/gfs and the ai
versions thereof. this will be important for where the best corridor
of severe thunderstorm potential develops on sunday
afternoon/evening. further east, a surface front will sag southward
across the upper oh valley and portions of the mid-atlantic. between
these surface boundaries, a seasonally very moist airmass will exist
across at least eastern portions of the plains to the ms valley and
the southern mid-atlantic.
...northern plains/upper midwest vicinity...
the forecast for sunday is highly uncertain. forecast guidance
suggests a shortwave impulse and/or mcv will move across northern mn
during the afternoon/evening. this area will be beneath the upper
ridge axis and could be capped. however, a very moist airmass will
be in place beneath steep midlevel lapse rates. furthermore, a
strong southerly low-level jet is expected to focus from the central
plains to the upper ms valley during the evening/nighttime hours. if
storms can develop and become near-surface based, potential for
damaging wind gusts and large hail will be possible. this scenario
is generally supported by the rrfs and gsl mpas, though
location/timing varies.
forecast guidance develops additional areas of convection across
portions of western ne/central sd into nd on the western periphery
of stronger capping and near the surface trough/dryline within the
gradient of stronger instability. this scenario is uncertain, both
regarding storm development, and if storms occur, whether or not
they will be surface-based. however, if storms do develop, an
intense low-level jet within the strongly unstable airmass during
the evening/overnight hours could support damaging wind potential.
the marginal risk (level 1 of 5) has been adjusted to reflect this
conditional risk.
...southern mid-atlantic...
forecast guidance suggests an mcv will move across the central
appalachians into parts of va/nc on sunday. deep-layer flow is not
expected to be particularly strong, but this feature could locally
enhanced vertical shear, with some guidance showing effective shear
magnitudes up to 25 kt are possible. a seasonally very moist airmass
will reside east of the higher terrain across southeast va into the
eastern carolinas, supporting moderate destabilization as strong
daytime heating occurs. thunderstorms will pose an isolated damaging
wind risk into early evening.
..leitman.. 06/26/2026
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note: the next day 3 outlook is scheduled by 0730z