SPC Jun 18, 2025 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1228 AM CDT Wed Jun 18 2025

Valid 181200Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
MISSOURI INTO SOUTHERN LOWER MICHIGAN AND WESTERN OHIO...

...SUMMARY...
Strong to severe storms are expected today from parts of southern
Missouri northeastward into southern lower Michigan and western
Ohio. Damaging winds, isolated hail, and a few tornadoes will be
possible. More isolated severe storms may develop across the
southern Plains.

...Midwest/Southern Great Lakes...

A shortwave upper trough is forecast to move across the Mid-MS
Valley and Midwest today. A swath of enhanced deep-layer
southwesterly flow ahead of this feature will overspread portions of
the Ozarks to the Ohio Valley and southern Great Lakes ahead of a
surface front. A seasonally warm and moist airmass ahead of the
front/composite outflow will support moderate destabilization. A
surface low/MCV will develop northeast across central/northern IL to
southern Lower MI during the afternoon into early evening. The
current expectation is that thunderstorms will develop ahead of the
surface low and front, with a mix of clusters and line segments.
Midlevel lapse rates will remain modest, but isolated large hail is
possible. More likely, damaging gusts will be the main hazard as
linear convection develops ahead of the front. Tornado potential is
possible near the surface low from portions of northeast IL into
northern IN/southern Lower MI where low-level shear may be
maximized. However, forecast guidance varies considerable regarding
this scenario, so will maintain 5 percent tornado probabilities at
this time. 

...TX/OK to the Mid-South...

A very moist and unstable airmass will be in place across the
region. A northeast to southwest oriented outflow boundary related
to an MCS that is currently ongoing across northern OK as of 06z
this morning will be draped across the Red River/southern OK
vicinity into the Ozarks. Isolated to scattered thunderstorms are
expected to develop diurnally. Large-scale ascent will be nebulous,
but supercell wind profiles and strong instability/steep lapse rates
will support isolated damaging wind and hail potential.

...Northern Plains...

Modest boundary layer moisture beneath steep midlevel lapse rates
will support weak diurnal destabilization. Increasing
west/northwesterly flow with height will provide sufficient shear
for some storm organization and elongated/straight hodographs are
indicated in forecast soundings. Furthermore, a deeply mixed
boundary layer is evident. This should support isolated hail and
strong gusts during the afternoon/early evening. 

...Mid-Atlantic...

Strong heating of a very moist airmass will support moderate
destabilization. Deep-layer westerly flow will remain somewhat weak,
but sufficient for multicell clusters. Strong gusts may accompany
this activity.

..Leitman/Weinman.. 06/18/2025

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