442
ACUS02 KWNS 110600
SWODY2
SPC AC 110558

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Fri Jul 11 2025

Valid 121200Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHEAST
INDIANA...NORTHWEST OHIO...AND MUCH OF EASTERN MICHIGAN...

...SUMMARY...
Scattered damaging winds are possible across northeast Indiana,
northwest Ohio, into eastern Michigan on Saturday. A broad swath of
isolated severe thunderstorms is anticipated from the Great Lakes to
the southern High Plains, mainly Saturday afternoon/evening.

... Synopsis ...

The large-scale pattern across the US on Saturday will feature
mid-level ridges on both coasts and a broad trough across the
central US. Within this cyclonic flow, multiple vorticity ribbons
will quickly move northeast across the Great Lakes and into Ontario.

At the surface, a cold front will stretch from Wisconsin southwest
into northwest Oklahoma and the Texas Panhandles at the start of the
forecast period and should move east across Michigan while making
little forward progress across the southern Great Plains.

... Great Lakes Region ...

A lead shortwave trough/vorticity maximum will quickly move through
eastern Wisconsin and lower Michigan during the late morning into
afternoon. In response to the approaching trough, a modest low-level
jet will support surface dewpoints rising to/being sustained in the
upper 60Fs to lower 70Fs range. Given the degree of low-level
moisture, modest diurnal heating will support most-unstable CAPE
values in excess of 2000 J/kg.

As large-scale ascent overspreads the surface cold front across
lower Michigan, one or more bands of convection are expected to
develop along and ahead of the front. Despite effective-layer shear
being generally less than 35 knots, some severe potential will exist
with this convection -- primarily strong downdraft winds -- owing to
the degree of instability and precipitable water values around
1.75". Additionally, with a modest low-level jet and a preexisting
boundary in the vicinity, a tornado or two cannot be ruled out.

Farther west, in response to the large-scale ascent for the second,
stronger shortwave trough, a second round of thunderstorms may
develop across portions of Wisconsin and the Upper Peninsula of
Michigan. Despite being post frontal, diurnal heating and residual
low-level moisture will support most-unstable CAPE around 1000-1500
J/kg. Isolated large hail and strong thunderstorm outflows will be
possible.

... Central and Southern Rockies into the Southern Plains ...

One or more decaying MCSs and perhaps attendant MCVs may be ongoing
at the start of the period across the Texas/Oklahoma Panhandles into
Oklahoma. The combination of multiple potential outflow boundaries
and localized ascent associated with any MCV will result in
scattered to widespread thunderstorm development through the period.
Diurnal heating of a very moist airmass will result in CAPE values
perhaps as high as 3000 J/kg across portions of the area. This
degree of instability coupled with precipitable water values
approaching 2 inches will yield the potential for wet microbursts
and associated damaging winds. Despite wind being the more likely
severe threat, isolated large hail may also be possible given the
degree of instability, especially early in the thunderstorm life
cycle.

During the afternoon, additional thunderstorms are anticipated
across the higher terrain of the central and southern Rockies within
a moist upslope low-level flow. Modest northwesterly mid-level flow
and perhaps a subtle short-wave trough will help organize the
convection into a slow moving south-southeast moving MCS. If
confidence increases in a well-organized MCS, the area may need to
be upgraded to categorical upgrade to Level 2/Slight Risk driven by
wind potential.

..Marsh.. 07/11/2025

$$