280
ACUS48 KWNS 150900
SWOD48
SPC AC 150859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sun Jun 15 2025

Valid 181200Z - 231200Z

...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
A mid-level trough is forecast to move through the Upper Midwest on
Wednesday, as a cold front advances southeastward into the lower
Missouri and mid-Mississippi Valleys. Ahead of the front, moderate
instability is forecast to develop by afternoon. Thunderstorms
appear likely to form along parts of the front, with several
clusters or line segments moving eastward toward the instability
axis during the late afternoon and early evening. Moderate
deep-layer shear should support severe storms with large hail and
wind damage as the primary threats.

The mid-level trough is forecast to move into the lower Great Lakes
and upper Ohio Valley on Thursday, as the cold front advances into
the central Appalachians. As the airmass ahead of the front
destabilizes, scattered thunderstorms are expected to form along and
ahead of the front. The models suggest that moderate deep-layer
shear will be in place across much of the northeastern U.S., which
will likely support organized storms. Damaging winds gusts will be
the most likely severe threat.

...Friday/Day 6 to Sunday/Day 8...
A shortwave mid-level ridge is forecast to move into the upper
Mississippi Valley on Friday. The ridge is forecast to remain over
the region on Saturday as mid-level heights rise. Beneath the ridge,
a moist and unstable airmass will likely be in place from the lower
to mid Missouri Valley northeastward into the western Great Lakes.
Within this airmass, isolated thunderstorm development should take
place both Friday and Saturday afternoon. Instability and deep-layer
shear appear sufficient for a localized severe threat. However, the
presence of the ridge introduces uncertainty as to where the
greatest potential for convection will be. For this reason,
predictability is low.

On Sunday, a mid-level trough is forecast to develop over the
Rockies as a ridge moves into the Great Lakes region. Although a
moist and unstable airmass should be located over parts of the
northern and eastern U.S., large-scale ascent and mid-level flow is
forecast to be relatively weak in most areas. For this reason, any
severe potential is expected to remain isolated.

..Broyles.. 06/15/2025