spc ac 201723
day 2 convective outlook
nws storm prediction center norman ok
1223 pm cdt sat jun 20 2026
valid 211200z - 221200z
...there is a slight risk of severe thunderstorms from the central
high plains into the ohio valley...
...summary...
severe storms are possible along a frontal zone from the ohio valley
to the central high plains from sunday afternoon into night. large
to very large hail, severe winds, and tornadoes (some of which could
be strong) will be possible.
...synopsis...
a series of vorticity maxima, some with convective origins, will
translate east through the central plains and oh valley, along with
a belt of 40-50+ kt winds at 500 mb. in the lower levels, a
southwesterly low-level jet (llj) initially from the southern plains
into the mid mo valley sunday morning is forecast to migrate east
into the mid ms and oh valleys, immediately ahead of a surface low
tracking through the lower mo valley into il/in. a cold front will
trail the surface low, likely extending southwest through the lower
mo valley into southern ks or northern ok and the tx panhandle by
mid to late afternoon.
...missouri into the oh valley...
latest models remain consistent with previous runs in depicting one
or multiple mcss ongoing at 12z sunday along the llj axis from
eastern ks into parts of northern and central mo. while the models
signal a general decrease in storm coverage through the morning, the
presence of modestly strong vertical shear suggests the potential
for isolated occurrences of damaging winds and perhaps some hail
across mo into western il.
renewed storm development is anticipated by afternoon from il/in in
the vicinity of a remnant mcv west/southwest along the trailing
outflow/warm frontal boundary to the primary surface low over the
lower mo valley. enhanced warm thermal and moisture fluxes occurring
along the llj are expected to support air mass recovery in the wake
of the early-day storms with moderate to potentially strong
instability forecast from the lower oh valley into the ozarks, south
of the composite boundary.
forecast soundings and plan-view kinematic fields indicate
relatively strong low-level and deep-layer shear in the vicinity of
the composite boundary across portions of mo/il/in sunday afternoon
into evening, where the highest probability of supercells and/or
bowing structures capable of all hazards (including strong
tornadoes) is expected to exist. however, as was alluded to in the
initial day 2 discussion, and is still the case, there is
considerable latitudinal variability in the composite boundary
location. as such, uncertainty remains too high to delineate higher
severe-weather probabilities for this region.
...central high plains...
a trailing vorticity lobe and western extension of a 40-50 kt
mid-level jet maximum are expected to support weak cyclogenesis
along a front or trough pushing into the region from the west. ahead
of that boundary, steep low/mid-level lapse rates and modest
boundary-layer moisture content are expected to yield moderate
afternoon instability amidst sufficiently strong deep-layer shear to
support supercell storm modes capable of large to very large hail.
most recent model guidance has shifted the corridor of preferred
storm development and residence slightly east across portions of
western and central ne into northwest ks, and the severe-weather
probabilities have been adjusted accordingly. storms may congeal
into clusters sunday evening with the severe-weather threat
transitioning more to damaging winds.
...southern kansas and northern oklahoma into the ozark plateau...
high-resolution model guidance suggests that a sub-synoptic-scale
surface low/frontal wave may evolve sunday afternoon along the
trailing front. enhanced convergence near and east of that feature
should be sufficient to overcome the cap and allow for isolated to
widely scattered storm development. the combination of moderate to
strong instability and around 40 kt of deep-layer shear will support
supercells as the initial storm mode with a risk for large to very
large hail. a largely parallel orientation of the deep shear vector
to the surface front suggests the potential for merging storms
within a few hours after initiation, with damaging wind potential
increasing at that time. storms are expected to grow upscale into
one or multiple mcss with at least an isolated damaging-wind threat
spreading south through the ozark plateau region sunday night.
..mead.. 06/20/2026
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note: the next day 2 outlook is scheduled by 0600z