ACUS02 KWNS 130559
SWODY2
SPC AC 130558

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Fri Jun 13 2025

Valid 141200Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Scattered severe storms capable of large hail and isolated damaging
wind gusts will be possible across parts of the central and northern
High Plains Saturday afternoon and evening. Marginally severe storms
will also be possible in parts of southern and central Plains.

...Central and Northern High Plains...
A mid-level ridge will move eastward across the north-central U.S.
on Saturday. In the wake of the ridge, a subtle shortwave trough
will move into the central and northern High Plains. At the surface,
a moist airmass will be present across much of the Great Plains.
Upslope flow will be in place over the central and northern High
Plains, where a pocket of moderate to strong instability is forecast
to develop Saturday afternoon. As surface temperatures warm during
the day, convection will first initiate in the higher terrain from
east-central Montana southeastward to the Black Hills. From this
convection, scattered thunderstorms are expected to develop and move
eastward into the lower elevations of the central and northern High Plains.

An impressive thermodynamic environment is forecast to be in place
by Saturday afternoon from northeast Wyoming into western Nebraska,
where model forecasts suggest MLCAPE could peak around 4000 J/kg.
Near the instability maximum, 700-500 mb lapse rates are forecast to
be near 8 C/km. In spite of this, forecast soundings in the central
and northern High Plains have a capping inversion in place during
the afternoon. This should keep the initial convective development
confined to the higher terrain of southeast Montana, northeast
Wyoming and southwestern South Dakota. Forecasts soundings late
Saturday afternoon in this area mostly have 0-6 km shear in the 30
to 40 knot range, mainly due to mid-level speed shear. The shear,
combined with the moderate to strong instability, will likely
support a severe threat. Supercells should be capable of isolated
large hail and severe wind gusts. The threat is expected to persist
into the mid to late evening, as low-level flow increases.

...Southern and Central Plains...
A mid-level ridge will move eastward across the Great Plains on
Saturday. At the surface, a moist airmass will be located across
much of the southern and central Plains. As surface temperatures
warm during the day, moderate instability is forecast to develop
throughout much of this airmass. Due to the presence of the ridge,
large-scale ascent will remain weak in most areas. In spite of this,
isolated thunderstorms may still develop in areas where low-level
convergence and surface heating are maximized, and further west in
the higher terrain of the central and southern High Plains. Forecast
soundings late Saturday afternoon across the southern and central
Plains generally have large surface-temperature dewpoint spreads
with steep lapse rates. This environment will also have sufficient
deep-layer shear for isolated severe storms. Hail and marginally
severe wind gusts are expected to be the primary threats.

..Broyles.. 06/13/2025

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