6:21 PM Monday, July 17, 2023
Isolated showers will linger across parts of the Northland this evening and an isolated shower or two is possible again on Tuesday, but a system moving through late Tuesday night through Wednesday night has a much greater chance at producing a more widespread rain event in northeast Minnesota and northwest Wisconsin as this system looks to have better dynamics to work with along with some strong lift at times. This midweek system is similar to a clipper system that we sometimes see during the winter as an area of low pressure moves ESE out of Alberta along with an upper-level trough which digs SE out of west central Canada and into the upper Midwest and Great Lakes for Wednesday and Thursday.
Here’s the 500mb forecast valid Tuesday (7 AM) to Thursday (7 AM), July 18-20, 2023.
Note – Blue colors represent lower 500mb heights and a potential for unsettled weather.
As I mentioned above the system moving through on Wednesday does look to have some better dynamics with stronger winds aloft helping to generate better lift in the atmosphere to produce some rain at times.
Looks like we could see some showers and isolated thunderstorms move east and through parts of the Northland late Tuesday night lingering through about mid-morning Wednesday with a bit of a break in the rain possible for a few hours Wednesday afternoon, but more showers and some thunderstorms are possible by late Wednesday afternoon into Wednesday evening.
Note – There is a chance that we could see a few strong to severe thunderstorms Wednesday afternoon-evening mainly over east central Minnesota into far northwest Wisconsin, but if clouds and rain persist much of the day, this would tend to limit the amount of heating/instability that would develop later in the day which would reduce the threat for severe weather, but if we can get some clearing to take place to allow temperatures to warm and instability to climb, then there is a potential that we could see a few strong to severe storms develop later in the day Wednesday with all severe hazards in play including an isolated tornado or two since a warm front looks to setup somewhere over the Northland which could enhance the amount of wind shear over parts of that area, or near that warm frontal boundary.
Radar forecast valid Midnight tomorrow night to 7 PM Wednesday (Nam 3km model)
Rainfall totals of around a quarter to half an inch look pretty likely in northeast Minnesota and northwest Wisconsin Wednesday into early Thursday with localized higher amounts of an inch or more possible.
Isolated showers will come to an end by late this evening which will leave us with mainly dry conditions overnight and through much of the day Tuesday, but an isolated shower or two can’t be ruled out Tuesday afternoon.
Radar forecast through 7 PM Tuesday (Nam 3km model)
Quite an amplified pattern for this time of the year consisting of two upper-level troughs, one over eastern Canada and the Great Lakes, and the other over western Canada into the northern Rockies, while a massive upper-level ridge (heat dome) remains in place over the southwest U.S. today.
Goes-16 water vapor loop from Monday, July 17, 2023 (loop time ends 6 PM CT)
Thanks for reading!
Tim