/Issued 5:50 PM CDT, Monday, April 24, 2017/
A temperature gradient like the one that is forecast to be in place across the Northland Tuesday afternoon is a sure sign of a significant storm system. Check this out, 20s north of Minnesota to the 70s in western Upper Michigan. Weather nerds love this type of stuff!
Note: More details on the midweek and late weekend storm can be found a little farther down in this post.
Note: The risk area here in parts of the Northland is more for late Tuesday afternoon into early Wednesday morning.
A typical spring day around the Northland with strong NE winds (Cold temperatures near Lake Superior) while away from the lake in east central Minnesota and northwest Wisconsin temperatures were much warmer in the 60s.
Tonight's low temperature forecast. Source: https://graphical.weather.gov
Tuesday's high temperature forecast. Source: https://graphical.weather.gov
Weather Synopsis for northeast Minnesota and northwest Wisconsin
A very wind and cool day near Lake Superior today with highs in the upper 30s along with east/northeast winds at 15 to 30 mph with gusts to around 40 mph. Away from Lake Superior highs made it into the 60s from around the Brainerd Lakes, Hinckley, Solon Springs, Hayward Lakes and Park Falls area with upper 30s and mid 40s from the Iron Range and Borderland areas. Low pressure was over far western Minnesota late this afternoon and some showers have been developing today in western-northern portions of the area as forcing increases as the surface low to our west moves closer to our area.
The low over western Minnesota will continue to move toward the E/NE tonight while a warm front over central Minnesota moves a little more to the NE while a cold front moves toward the east...The cold front by Tuesday morning is forecast to be over eastern Minnesota, and by Tuesday evening this front is forecast to extend from southern Minnesota toward west central Upper Michigan -- Occasional showers around the Northland for tonight, temperatures aloft and near the surface will remain warm enough for the precipitation to remain in the form of rain tonight. Lows will range from the 30s in far northern Minnesota and near Lake Superior to the 40s elsewhere while a few locations in the far south remain around 50 degrees.
A brief break in the rain is expected Tuesday morning but rain is forecast to increase in coverage from SW-NE Tuesday afternoon into Tuesday evening. There should be better lift and dynamics in place for a more widespread precipitation event Tuesday night compared to tonight. Highs Tuesday will range from the 60s in eastern Minnesota and most of northwest Wisconsin with 30s in far northern Minnesota.
A variety of precipitation types on the table from late Tuesday night into Wednesday. High pressure near Hudson Bay Canada will help bring colder air down on N/NE winds while low pressure to our SE brings moisture up into our area while it interacts with the cooling temps -- The net result from all this will be for the rain to mix with and change to freezing rain, sleet and snow from north to south across northeast Minnesota Tuesday night and potentially in portions of northwest Wisconsin mainly inland from Lake Superior. Note: Significant amounts of ice or sleet could accumulate late Tuesday night into Wednesday in parts of northeast Minnesota, there is also a chance for some snow accumulation, possibly in the 1-4 inch range the way it looks now.
As for the Twin Ports, North Shore and South Shore of Lake Superior -- Difficult forecast ahead from late Tuesday night through Wednesday. I think the higher elevated areas inland from Lake Superior stand the best chance at seeing the rain mix with and change to freezing rain, sleet or snow late Tuesday night and Wednesday while locations below the hill in the Twin Ports have a lesser chance for freezing rain (Ice accumulations) but sleet may occur even at lower elevation areas by Wednesday morning. With no ice covering Lake Superior it will be difficult to get the surface temperature cold enough to produce freezing rain. Water temperatures over Lake Superior are right around 38 degrees, but if there was more ice coverage over the lake, these water temps would likely be a few degrees colder which would in turn increase the risk for icing even closer to Lake Superior, but that just isn't the case with this event. Will have to rely on cold air advection to get the surface temperature low enough to support freezing rain, I just don't see enough cold air advection occurring by the lake for a freezing rain event, but still gotta watch it to see how it plays out.
As for the late weekend system, model trends today is taking this system more to the east which means a decreased threat of snow or rain in northeast Minnesota while a potential for snow or mixed precipitation continues over portions of northwest Wisconsin later this weekend.
Forecast for Duluth and Superior
.Tonight... Windy. Occasional showers. Mostly cloudy. Low 35 to 37. Wind east to northeast at 15 to 25 mph with higher gusts especially this evening.
.Tuesday... Partly to mostly cloudy. Showers possible early and again later in the day. High 52 to 57 but cooler near Lake Superior. Wind northeast at 10 to 20 mph.
Normal temperatures for Tuesday
Sunrise Tuesday: 6:03 AM CDT
Sunset Tuesday: 8:11 PM CDT