ACUS02 KWNS 170552
SWODY2
SPC AC 170551

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CDT Thu Apr 17 2025

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM LOWER
MICHIGAN TO THE SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are possible from the parts of the
Great Lakes to the southern Great Plains, mainly during the late
afternoon Friday into Friday night. Large hail and isolated severe
gusts will be the main hazards with this activity.

...Synopsis...

A positive-tilt large-scale upper trough will pivot south and east
across portions of the north-central to western U.S. on Friday. A
swath of 60-80 kt 500 mb flow will stretch from the southern Rockies
to the Great Lakes ahead of the upper trough. At the surface, low
pressure will develop northeast from the KS/MO/IA vicinity Friday
morning, to southern Ontario/Quebec by early Saturday. As this
occurs, a cold front will develop southeast across portions of the
Mid-MS Valley/Great Lakes and southern Plains. A weak secondary
surface low likely will develop across west TX, where a dryline will
extend southward from the eastern Panhandle to the Big Bend region.

Southerly low-level flow will transport modest boundary-layer
moisture northward ahead of these surface features and beneath fast
mid/upper southwesterly flow. This will support scattered severe
storms late Friday afternoon into the overnight hours from portions
of the southern Plains to the Great Lakes.

...Lower-MO/Mid-MS Valley to Great Lakes...

Elevated thunderstorms north of a warm front will likely be ongoing
during the morning into the afternoon across WI/northern MI. This
activity may pose a risk for marginally severe hail.

Meanwhile, a shortwave upper trough embedded within the northern
branch of the larger-scale western U.S. upper trough will shift east
across the northern Plains and Upper Midwest during the
evening/overnight. This will facilitate the eastward progression of
the surface front through the period, creating a focus for
thunderstorm development. However, strong capping will limit
development along the front, likely until closer to 00z, when
stronger large-scale ascent overspreads the surface boundary and
cooling aloft ensues. Thunderstorms will likely remain elevated atop
the strong EML in the 850-700 mb layer, and will likely become
undercut by the surface cold front given boundary-parallel flow
through the cloud-bearing layer. Nevertheless, steep midlevel lapse
rates and sufficient MUCAPE will support organized convection
capable of producing large hail. With time, cells may become
training clusters, posing some isolated risk for damaging gusts.

...Southern Plains Vicinity...

As a surface low develops across west TX, a triple point will emerge
near the eastern TX Panhandle/South Plains vicinity. A stout EML
will preclude convective development for much of the day. Near the
triple point and northeast along the advancing cold front, isolated
to scattered thunderstorms should form in the 22-00z time frame.
Supercell wind profiles with large MUCAPE, very steep lapse rates,
and elongated hodographs suggests initial supercells will pose a
risk for large to very large hail through early evening. Thereafter, boundary-parallel flow will result in clustering/training as
convection also becomes undercut by the front. Damaging gusts also
may occur with initial supercells given a well-mixed boundary
layer/steep low-level lapse rates beneath the EML. Additionally,
some strong gust potential could occur into the Ozarks vicinity as
clustering ensues, but hail is expected to be the main concern.

..Leitman.. 04/17/2025

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