707
ACUS03 KWNS 130729
SWODY3
SPC AC 130729

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CDT Sat Jul 13 2024

Valid 151200Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
MIDWEST INTO PORTIONS OF THE MID MS VALLEY AND UPPER GREAT LAKES...

...SUMMARY...
Strong to severe thunderstorms are possible from the Upper Midwest
into the Mid Mississippi Valley and Upper Great Lakes region on
Monday.

...Synopsis and Discussion...
A belt of modestly cyclonic flow will likely be in place across the
northern CONUS early Monday morning, with this belt situated between
upper ridging across the southern CONUS and upper troughing across
north-central Canada. A shortwave trough is expected to progress
through this cyclonic flow, moving from southern Manitoba/ND
eastward across far northwest Ontario/northern MN before lifting
into more of northwest Ontario. Another convectively augmented
shortwave trough may move from SD and NE through the Mid MS Valley,
briefly phasing with the northern shortwave trough.

Thunderstorms will likely be ongoing Monday morning over western MN,
along and ahead of a modest cold front. These storms should be north
of the warm front, which is expected to extend from a surface low
near the SD/MN/IA border intersection vicinity east-southeastward to
far northern IL. Two scenarios appear plausible with these storms:
1) continued progression southeastward throughout the day ahead of
the cold front with a transition to a more surface-based character
possible amid interaction with the warm front, or 2) dissipation
with new development or significant reintensification occurring near
the warm front during the afternoon. Both scenarios suggest the
development of a forward-propagating MCS is possible, with the most
likely corridor for this MCS from eastern IA and southern WI across
northern IL, potentially reaching southwest Lower MI and northern
IN. Damaging gusts would be the primary threat within this MCS.

Afternoon/early evening thunderstorms are possible farther east from
the Upper OH Valley into the Northeast as a modest shortwave trough
interacts with the warm and moist airmass over the region. Shear
will likely be weak, mitigating the organized storm potential and
likely keeping the severe threat isolated.

..Mosier.. 07/13/2024

$$