735
ACUS02 KWNS 150603
SWODY2
SPC AC 150602

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Sun Jun 15 2025

Valid 161200Z - 171200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN SOUTH DAKOTA...MINNESOTA AND NORTHWESTERN WISCONSIN...

...SUMMARY...
Scattered severe storms with large to very large hail and wind
damage are expected on Monday from the north-central High Plains
northeastward into the upper Mississippi Valley. Outside of this
area, marginally severe storms will be possible across much of the
central and northern U.S.

...Minnesota/Wisconsin/South Dakota/Iowa/Nebraska...
A mid-level shortwave trough will move eastward across the Dakotas
on Monday, as an associated 45 to 60 knot mid-level jet translates
eastward through the system. At the surface, a cold front will
advance southward through the northern Plains. Convection will
initially develop near the front across the Dakotas during the late
morning, moving eastward into central and northern Minnesota during
the afternoon. This activity will likely have an isolated severe
threat. To the south of the front, surface dewpoints from the mid
60s to the low 70s F will contribute to moderate to strong
instability by afternoon. Convective initiation further to the south
across parts of southeastern South Dakota and south-central
Minnesota should hold off until late afternoon when low-level
convergence along the front is expected to become maximized.
Scattered severe thunderstorms will likely develop near and to the
south of the front, moving eastward into the upper Mississippi
Valley from late afternoon into the evening.

NAM forecast soundings along and near the instability axis late
Monday afternoon have MLCAPE peaking in the 2500 to 3500 J/kg range,
with 0-6 km shear near 50 knots. This, combined with 700-500 mb
lapse rates of 7.5 to 8.5 C/km, will be favorable for supercells
with large hail. Mid-level lapse rates and instability is forecast
to be greatest from far northeast Nebraska into southeast South
Dakota and south-central Minnesota, where supercells could produce
hailstones greater than 2 inches in diameter. The greatest severe
threat coverage is expected from far eastern South Dakota into
southwest and central Minnesota, where large-scale ascent will be
enhanced by the exit region of the mid-level jet. This area will
also have a strong low-level jet response, which is forecast to
increase 0-3 km storm-relative helicity into the 250 to 350 m2/s2
range by early evening. As a result, a tornado threat is also
expected. Wind damage will also be possible with supercells and
short bowing line segments.

...Kansas/Oklahoma...
A very moist and unstable airmass will be in place across much of
the southern and central Plains on Monday. Surface dewpoints will be
in the mid 60s to the lower 70s F. As surface temperatures warm
during the day, MLCAPE is forecast to increase into the 3000 to 4000
J/kg range. Within this unstable airmass, a substantial amount of
low to mid-level directional shear is forecast. This will support an
isolated severe threat with any cells that can overcome the warm air
aloft. The greatest potential for isolated severe storms should be
along any pre-existing boundaries, mainly during the late afternoon
and early evening.

...Northern Rockies/North Dakota...
A post-frontal airmass will be in place from the northern Rockies
eastward into North Dakota. Surface dewpoints in the 50s F will
contribute to moderate instability over much of the region by
afternoon. Scattered thunderstorms appear likely to develop in the
higher terrain of the northern Rockies and northern High Plains as
surface temperatures warm during the day. Due to a lack of
large-scale ascent, convective coverage should remain isolated.
Deep-layer shear is forecast to be strong enough for isolated severe
storms. Hail and strong wind gusts will be the primary threats.

..Broyles.. 06/15/2025

$$