Rain late tonight into Monday morning; gusty winds on Monday; Gale event possible over Lake Superior Thursday

*This evening looks mainly dry in Duluth, but a few showers can’t be ruled later this evening in the 10 PM to Midnight time frame, but a better chance for widespread rain occurs roughly in the 2 AM to 10 AM time frame (+/- an hour)

*Rain ends in Duluth late Monday morning with some clearing expected by Monday afternoon.

*A period of strong NW winds are possible lasting roughly an hour or two Monday morning (somewhere in the 7-10 AM time frame) wind gusts 30-40 mph are possible.

*Breezy conditions continue Monday afternoon, with west winds gusting 15 to 25 mph.

*Highs across the Northland on Monday will mainly be in the 60s, although a few locations might get close to 70 degrees late Monday afternoon.

*Looking ahead to Tuesday and Wednesday’s weather features warmer temperatures across the Northland with highs in the 70s. Looks breezy both days with a southwest wind Tuesday and a west-southwest wind for Wednesday. Isolated showers or thunderstorms are possible mainly over northern Minnesota Tuesday evening, otherwise it looks mostly dry Tuesday and Wednesday.

*Next week’s shot of very cool air is still showing up on model guidance today with a potential for the first frost and or freeze of the season for much of the Northland around September 7-11.

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Here comes our rain event for late tonight. This system is pretty strong so it should bring a widespread light to moderate rainfall to northeast Minnesota and northwest Wisconsin from late tonight through Monday morning.

Source: Goes-16 water vapor loop from Sunday, August 30, 2020; https://weather.cod.edu/

There should be some fairly strong forcing accompanying this system late tonight into Monday morning noted by the red colors on this animation. As this system moves closer to the Northland we should see rain become more widespread especially after Midnight tonight once better forcing approaches from the WSW.

Source: 18z NAM model 8.30.2020; https://www.tropicaltidbits.com/

18z NAM 3km model simulated radar forecast from 7 this evening to 7 Monday evening – Rain begins in western and southern portions of the Northland mid to late evening and then spreads into northeast Minnesota and northwest Wisconsin after Midnight tonight. Rain ends from SW-NE Monday morning, but rain could linger over the Arrowhead of Minnesota into early Monday afternoon before this system moves away.

Source: https://weathermodels.com/

Computer models have increased rain totals with tonight’s system, especially around the Twin Ports area and far northwest Wisconsin, rain totals in these areas could reach a half inch, while around an inch of rain is possible from Bigfork and International Falls, east to Ely and Grand Marais. The least amount of rain is forecast to fall around the Hayward, Ashland and Hurley areas with amounts generally around a quarter inch or so.

Note: August 14th was the last time where the Duluth Airport picked up at least a quarter inch of rain (0.38″) and there’s only been 3 rainfall events so far this month with 0.25″ or more of rain at the Duluth Airport, greatest was on August 7th with 0.71″ of rain.

Source: https://lab.weathermodels.com/

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Meteorological summer is quickly coming to an end, in fact Monday, August 31st marks the final day of meteorological summer 2020.

Meteorological seasons

Summer: June 1 to August 31

Fall: September 1 to November 30

Winter: December 1 to February 28 (February 29 in a leap year)

Spring: March 1 to May 31

Let’s take a look at some climate stats from around the Northland for the summer of 2020 – Stats below are from June 1st to August 29th, so with 2 days left to go of summer 2020 the stats below could change just a little bit.

Source: https://www.dnr.state.mn.us/

Leech Lake, Minnesota

Average temperature: 68.3 degrees
Departure: +2.0 degrees above normal

Total precipitation: 15.89″
Departure: +4.92″ above normal

Duluth, Minnesota

Average temperature: 67.2 degrees
Departure: +3.2 degrees above normal

Total precipitation: 7.91″
Departure: -3.62″ below normal

38 days with a high temperature of at least 80 degrees. Average for the summer is 23 days. Last summer had 42 days with a high temperature of at least 80 degrees.

2 days with a high temperature of at least 90 degrees. We had 0 days in the 90s last summer.

Superior, Wisconsin

Average temperature: 66.7 degrees
Departure: +2.9 degrees above normal

Total precipitation: 9.75″
Departure: -1.81″ below normal

International Falls, Minnesota

Average temperature: 65.3 degrees
Departure: +2.2 degrees above normal

Total precipitation: 10.36″
Departure: +0.11″ above normal

Hibbing, Minnesota

Average temperature: 63.8 degrees
Departure: +1.7 degrees above normal

Total precipitation: 12.92″
Departure: +1.44″ above normal

Summary: Summer of 2020 was warmer than average across northeast Minnesota and northwest Wisconsin as average temperatures for the three month period of June, July and August came in anywhere from 1 to 3 degrees above normal. Precipitation totals have varied considerably this summer, ranging from around 8 inches at the Duluth Airport to nearly 16 inches at Leech Lake.
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A westerly gale event is possible across Lake Superior on Thursday, September 3rd as a deep area of low pressure passes NW of Lake Superior.

The GFS model from Sunday morning is the deepest with the low, bottoming out in the 971-977mb range as it passes north of Lake Superior on Thursday.

Note: With a west wind, the largest waves would be east of Duluth and Superior on Thursday.

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

The main impact in the Northland with the system for late this week would be from gusty winds as most of the rain looks to stay further north in Ontario.

Shown below is the 850mb wind forecast from 7 PM Wednesday to 7 PM Thursday. Those red colors indicate winds of 50 to around 70 knots up at ~5000 feet, some of that wind will likely mix down to the surface resulting in some strong gusty winds Wednesday evening into Thursday.

Thanks for reading!

Tim

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