ACUS01 KWNS 131243
SWODY1
SPC AC 131242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Sat Sep 13 2025

Valid 131300Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NEW MEXICO
NORTH INTO THE DAKOTAS...AND OVER PORTIONS OF THE MIDWEST...

...SUMMARY...
Isolated severe wind and hail will be possible from the
Southwest/southern Rockies to the northern Great Plains and a
portion of the Midwest, mainly today into early tonight.

...Southwest/southern Rockies/High Plains...
An increase in thunderstorm coverage is anticipated from CO south
into NM today as ascent/mid-level cooling with the western U.S.
upper trough and several embedded vorticity maxima overspread the
region. Extensive cloud cover will tend to limit the potential for
widespread significant destabilization, with generally modest MLCAPE
(at or below 1000 J/kg) over much of the area from CO southward into
northern/western NM. Over portions of southern/eastern NM, however,
higher surface dew points surging northwest from southwestern TX
should help to focus a region of greater instability, with MLCAPE of
1000 to locally near 1500 J/kg possible by afternoon. Ongoing
thunderstorms should expand in coverage and increase in intensity as
diurnal destabilization occurs, with isolated severe hail and wind
possible with the strongest storms.

Over southern/eastern NM, deep-layer shear will be more supportive
of organized updrafts as a belt of stronger mid-level flow develops
near the base of the trough, resulting in elongated hodographs.
Here, a somewhat more concentrated risk for severe hail and wind may
develop with a couple storms developing supercell structures. Higher
severe probabilities were considered for this area, however
lingering concerns over the effects of ongoing storms and related
cloud cover lowered confidence in increasing probabilities with this outlook.

...NE/SD/ND...
Strong storms were ongoing this morning over portions of the western
Dakotas in association with embedded impulses in advance of the
upper trough. The resulting extensive cloud cover/outflows from
multiple rounds of thunderstorms will tend to temper destabilization
later today within a modestly-sheared environment. Nevertheless,
some isolated severe wind/hail potential will exist as storms over
central SD move into ND today. Thunderstorms are expected to
redevelop across the central High Plains of NE/northeast CO later
this afternoon and evening and move into western SD tonight. Here,
sufficient diurnal destabilization in the wake of earlier convection
may result in a continued risk for isolated severe storms with
strong-damaging gusts and hail.

...IL/IN/WI...
A small cluster of thunderstorms over northeast IL/northwest IN,
associated with an earlier MCV over WI and ongoing/modest warm
advection, is expected to continue moving SSE in the short term
across eastern IL/far western IN. Some isolated severe wind and hail
potential may develop as this cluster of storms moves along an
intensifying instability gradient within a northwest flow regime
through at least early afternoon as boundary layer heating commences.

..Bunting/Broyles.. 09/13/2025

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