Severe Thunderstorm risk south of the Northland later tonight; chances for storms increase across the Northland Tuesday night/Wednesday morning

It was a warm late summer day across the Northland today as highs topped out in the upper 70s to lower 80s which is roughly 5 to 10 degrees warmer than normal for August 24th.

Tuesday looks like another mild day across the Northland with highs in the upper 70s to middle 80s, but it doesn’t look very humid. A stronger NE wind (gusts 15-25 mph) is also expected to develop near Lake Superior by Tuesday afternoon which should lead to a slight drop in temperatures by the lake by mid or late Tuesday afternoon.

Note: Duluth recorded its 4th day this month with a temperature of at least 80 degrees today, the average number of 80 degree days in August is 7 days. So far this summer (since June 1st) Duluth has had 37 days with a high temperature of at least 80 degrees compared to 42 days at or above 80 degrees all of last summer (June through August) The average number of 80 degree days in Duluth during the summer is 23 days.

Source: RTMA model 8.24.2020; https://lab.weathermodels.com/

Yes it was a warm one out there today, but humidity levels dropped off quite a bit this afternoon as dew points were only in the 50s across northern Minnesota. All the muggy stuff has been pushed farther south where dew points were in the 60s and lower 70s this afternoon, basically anywhere south of that red line on the map.

We could see a brief spike in dew points on Wednesday (60s to around 70 degrees) but for the most part it’s not looking too humid across the Northland over the next few days.

Source: RTMA model 8.24.2020

Widespread wildfire smoke covered areas from the western Dakotas to southern Minnesota south to the Central Plains today, but most of this smoke has remained south of northeast Minnesota and northwest Wisconsin today.

Note: The HRRR model shows the smoke currently over western North Dakota making its way into the Northland during the day Tuesday so we could see hazier skies as a result. Most of this smoke is expected to remain in the mid and upper levels of the atmosphere with no real issues expected in air quality across the Northland on Tuesday or Wednesday.

Source: https://weather.cod.edu/

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A frontal boundary which was located south of our area this afternoon is expected to lift back north as a warm front Tuesday night, along with it will come a risk for scattered showers and thunderstorms as warm, humid and unstable air lifts north into northeast Minnesota and northwest Wisconsin. Looks like these storms will start to develop Tuesday evening, but more so after Midnight and into Wednesday morning the way it looks now.

Note: The threat for severe weather is on the low side for Tuesday night, but we will have stronger winds aloft in place along with a pretty healthy elevated mixed layer as a plume of steep mid level lapse rates push in from the WSW, this combined with 0-6 KM shear and Effective Bulk Shear of 40 to 50 knots certainly supports a risk for at least isolated stronger storms across the Northland Tuesday night with large hail and gusty winds being the main threats.

The Northland should find itself in a pretty good spot for storm development Tuesday night as a very warm/capped air mass advects NE out of the Dakotas with 700mb temperatures as high as +14 to +16C.

Source: 18z NAM model 8.24.2020; https://weather.cod.edu/

Models are showing a nice looking boundary Tuesday night with SW winds across southern Minnesota shifting ESE across the Northland, this should help to get some storms to form in our area Tuesday night.

Source: 18z NAM model 8.24.2020

CAPE gradient which is south of our area this afternoon is forecast to shift NE into our area Tuesday night thanks to a SW low level jet which is forecast to increase to around 30-35 knots, this will advect higher amounts of CAPE into the Northland Tuesday night.

Source: 18z NAM model 8.24.2020

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Cooler risks are showing up for next week just in time for the start of Meteorological fall 2020, the period from September 1st to November 30th.

A system to our NW is forecast to move through the upper Midwest sometime in the Sunday-Monday time frame (August 30th-31st) behind this system we may see a stronger push of cool air move into the Northern Plains and upper Midwest next week.

Source: https://www.wpc.ncep.noaa.gov/

Here’s the temperature anomaly forecast for next week with the blue and green colors on the map indicating below normal temperatures.

Source: 12z European ensemble model 8.24.2020; https://weathermodels.com/

Thanks for reading!

Tim

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