954
ACUS03 KWNS 131932
SWODY3
SPC AC 131931

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0231 PM CDT Tue May 13 2025

Valid 151200Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
WISCONSIN...

...SUMMARY...
Scattered severe thunderstorms are likely across parts of the
western Great Lakes states and into parts of the Midwest Thursday
afternoon and evening. Very large hail and a few tornadoes may
occur. A more isolated/conditional severe threat will extend
southwestward from western Kentucky into Arkansas late.

...Synopsis...
An upper low will deepen over the northern Plains as a midlevel wave
ejects northeastward toward the upper MS Valley. A surface low will
also deepen over ND/MN, with occlusion. Extending southeast from the
low will be a warm front, which will rapidly jump into northern MN
and WI by late afternoon, and through much of Lower MI during the
evening. Southeast winds near this boundary will bring mid to
perhaps upper 60s F dewpoints northwestward, resulting in areas of
strong instability. Given the fast motion of the shortwave trough
and strongly veering winds in the low-levels, the primary severe
risk area may be relatively narrow.

The main front/dryline will stall near the OH River or Mid MS Valley
and southwestward toward the Ozarks. This corridor, primarily later
in the evening, will likely foster isolated severe storms  as well.

Elsewhere, a lingering upper trough will exit the Northeast, and
warm advection on the backside of this feature may support isolated
strong to severe storms from parts of PA into the Mid Atlantic
during the day.

...Upper MS Valley/Great Lakes/Midwest...
Models are in good agreement depicting a strong convective signal
near the MN/WI border by 20Z or so, with increasing coverage points
east through evening. Forecast soundings across WI and vicinity
depict steep lapse rates aloft and hodographs favoring supercells. A
strong tornado cannot be ruled out given the very favorable
thermodynamics, including a slight capping inversion atop the moist
boundary layer in combination with 200-300 m2/s2 ESRH.

Southeast of the Enhanced Risk area into IL and IN, storm coverage
looks to be more isolated. However, any supercells in this area will
have the same significant hail and tornado potential as points
north. This activity would likely wait until late in the day/after
21Z and closer to 00Z when heating is maximized to break the cap.

Nocturnal severe storms will also be likely across much of Lower MI,
northern IN and OH as activity moves in from the west. Supercells
producing large hail again appear likely.

...OH Valley into AR Late...
The aforementioned stalled boundary will be situated beneath
persistent southwest flow at 850 mb Thursday evening and overnight.
Robust moisture/high theta-e will be in place from eastern OK into
the OH Valley, and scattered storms are likely to develop overnight.
This area is a bit more conditional in terms of  coverage of severe,
but clearly large hail will be possible. A brief tornado may occur
as well although hodographs will be primarily straight by this time.

..Jewell.. 05/13/2025

$$