2:47 PM Sunday, August 28, 2022
There is a potential for isolated to scattered strong to severe thunderstorms over all of northeast Minnesota and northwest Wisconsin this evening. The lowest risk for severe weather is over the Minnesota Arrowhead, and over eastern portions of northwest Wisconsin.
Timing is from around 6 PM to 1 AM tonight, with storms impacting western portions of the Northland first, then spreading farther east into northwest Wisconsin later this evening, most likely after 9 PM.
For Duluth — Showers and thunderstorms are possible from around 9 PM to Midnight tonight.
Primary severe weather threats for late this afternoon/evening
-Large hail to 1″ in diameter
-Damaging winds to 60 mph
-An isolated tornado threat around the Brainerd Lakes area
There is also a threat for very large hail with a few of the storms late this afternoon and early this evening over parts of western and central Minnesota.
Hail up to golf ball to hen egg size (1.75″ to 2.00″ diameter) is possible in the green area on the map.
Storm ingredients/fuel
Plenty of low-level moisture is already in place for storms today with dew points in the mid 60s to around 70 over all of Minnesota.
Despite the widespread clouds over most of Minnesota today there is already a decent amount of instability with Mixed Layer CAPE of up to 2000 J/kg over western Minnesota, but there is also a cap in place as noted by the amount of CIN which is in the 100-250 J/kg range early this afternoon, this cap will need to erode in order for storms to develop.
Another sign of a cap is the warm 700mb temperatures of +10 to +12C covering much of western, central and southern Minnesota this afternoon.
An elevated mixed layer originating over the western High Plains is spreading a plume of steep mid-level lapse rates northeastward into the upper Midwest this afternoon with mid-level lapse rates of 7.0-8.5 C/km.
Often times will see thunderstorms form on the nose of higher Theta-E air which places northwest and west-central Minnesota in a favored zone for storm development later this afternoon since this area resides near the Theta-E ridge/bulge.
Dynamics aloft
A potent mid and upper-level low continues to spin to the east across southeast Saskatchewan this afternoon. Forcing will increase as this system moves closer to Minnesota later today, and this should in turn weaken the cap which should lead to scattered strong to severe thunderstorm development over western Minnesota late this afternoon.
Goes-16 water vapor loop ending 1:40 PM Sunday, August 28, 2022.
Stronger flow in the mid to upper levels of the atmosphere noted in blue will spread into the upper Midwest later today as a potent trough approaches from the WNW.
As these stronger winds move into the upper Midwest will see the amount of wind shear increase to around 30-40 knots which is favorable for storm organization.
Thanks for reading!
Tim
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