Conditions are still coming together for the potential of a higher end severe weather event from late this afternoon into this evening, primarily over far eastern Minnesota into parts of northwest Wisconsin. Primary severe weather hazards include large hail of golf ball to baseball size (1.75″ to 2.75″ in diameter) Damaging wind gusts of 65-85 mph and a risk for isolated tornadoes. I think the orange outlined area on the map below is where the greatest potential for severe weather will be in the Northland until around 9 PM tonight, that’s not to say a few severe storms won’t occur farther north and west, but the greatest chances based on what I’m seeing this afternoon would be in that orange outlined area.
Note: Scattered showers and thunderstorms and a risk for severe weather continues in Duluth and Superior until around 8 PM this evening.
Goes-16 visible satellite loop from Wednesday, July 28, 2021.
Storm Prediction Center Severe Weather Outlook as of 3 PM Wednesday.
18z NAM 3km model simulated radar forecast through Midnight tonight.
There’s an impressive temperature gradient in place today, with temperatures this afternoon ranging from 95 to 105 degrees from west-central and southern Minnesota, west into South Dakota, while 70s and 80s were common farther north in northeast Minnesota and northwest Wisconsin.
Lots of moisture in place for storms today with dew points in the mid 60s to upper 70s across the upper Midwest.
Also have a lot of warm air aloft, or a cap with 700mb temps of +14C pushing ENE out of southwest Minnesota this afternoon…Often times will see storms or clusters of storms develop while they move from NW-SE on the edge of this cap, or on the N/E side of said cap (black outlined area)
It’s taking a bit longer for the higher instability to work its way into eastern Minnesota and northern Wisconsin this afternoon, this is due in part to lingering cloud cover and scattered convection which has lingered into early this afternoon, but there is still a pool of very unstable air lurking to our SW as of 3 PM today, and at least some of this will push into the aforementioned areas through 5-6 PM today.
Plenty of wind shear for storms to tap into today with 50-60 knots of surface to 6km shear in place.
Storm relative helicity values of 100 m2/s2 to 200 m2/s2 over central Minnesota this afternoon will also move farther east through this evening, this combined with around 20-25 knots of surface to 1km shear could lead to an isolated tornado risk across parts of northwest Wisconsin and possibly into far eastern Minnesota from ~5 PM to 8 PM this evening.
Tim
