/Issued 5:05 PM CDT, Wednesday, April 19, 2017/
18z NAM 3km
Slight (Yellow) and Marginal (Dark Green) risks of severe thunderstorms tonight as far north as southern Minnesota and roughly the southern half of Wisconsin.
Tonight's low temperature forecast. Source: https://graphical.weather.gov
Thursday's high temperature forecast. Source: https://graphical.weather.gov
Weather Synopsis for northeast Minnesota and northwest Wisconsin
A break in the rain and snow today as Tuesday's system heads into eastern Canada while the next system organizes to our southwest over eastern Colorado and southern Nebraska. There is a very strong boundary that separates very warm air to the south and cooler air to the north, this boundary extended from southeast Nebraska to south central Iowa late this afternoon. Temperatures just north of that front were in the mid 50s to mid 60s while just south of that front temperatures were in the 80s! The Northland is well north of that frontal boundary today with temperatures in our area generally in the mid 40s to low 50s with upper 30s near Lake Superior. Winds out of the east or northeast have been increasing near Lake Superior today due to the difference in pressure between a high over western Ontario Province and the surface lows to our southwest.
Rain will spread northeast this evening into east central Minnesota and northwest Wisconsin as low pressure tracks into Iowa -- This low will move into south central Wisconsin Thursday morning then to northern Lower Michigan by late Thursday afternoon -- This system will continue to bring precipitation to portions of northeast Minnesota and northwest Wisconsin on Thursday with mainly dry conditions expected through Thursday in extreme northern Minnesota.
There is a chance for a few thunderstorms tonight over far southern areas of the Northland but the potential for severe thunderstorms will stay south of our area tonight.
Dynamical cooling will occur tonight and Thursday morning with temperatures aloft and near the surface becoming cold enough to support either a rain/snow mix, or a complete changeover from rain to snow in parts of the Northland.
850mb temperatures are forecast to drop to between 0 and -4 degrees C while 925mb temperatures fall to around -1 C. Meanwhile surface temperatures are expected to fall into the 30 to 34 degree range from late tonight through Thursday morning, rising a bit Thursday afternoon. These temperatures will support the potential for wintry precipitation, especially underneath heavier bands of precipitation from late tonight through early Thursday afternoon.
Now that we're heading into late April and with relatively warm ground temperatures it will be difficult for the snow to stick especially in lower elevation areas such as near Lake Superior, but inland locations away from Lake Superior in both northeast Minnesota and northwest Wisconsin stand a better chance for the snow to accumulate with a few inches of slushy accumulation expected by Thursday afternoon -- Motorists should be prepared to changing road conditions late tonight into Thursday morning with some roads possibly becoming slush and or snow covered mainly away from Lake Superior. Visibility could be reduced to around a mile due to the falling snow.
Another component to this spring storm will be the strong gusty winds near Lake Superior. East to northeast winds will continue to ramp up tonight with gusts of 25 to around 40 mph developing, these gusty winds will likely persist into early Thursday afternoon before they begin to diminish while shifting to the N/NW later Thursday afternoon.
Low temperatures tonight will be in the 30s with highs Thursday ranging from the mid 30s/low 40s in northwest Wisconsin and northeast Minnesota to the mid 40s/low 50s in the far west/northwest portions of the Northland.
Nicer spring weather is expected Friday-Saturday with daytime highs in the 50s to lower 60s on Friday (Cooler near Lake Superior) Highs Saturday look to be mainly in the 60s.
Note: The potential for a stormy weather pattern is setting up for next week with multiple low pressure systems possibly affecting the upper Midwest. April 24-25, and between April 27-30 is when the Northland could get more precipitation (Mostly rain the way it looks now) Gusty E/NE winds will also occur at times next week.
Forecast for Duluth and Superior
.Tonight... Windy. Rain developing after 8 PM. Rain mixing with and possibly changing to snow overnight especially on top of the hill. Low 33 to 35. Wind east to northeast at 15 to 30 mph with gusts to 40 mph.
.Thursday... Windy. Snow or a mix of snow and rain on top of the hill with snowfall accumulations of 1 to 3 inches possible. Rain, drizzle and some snow below the hill with up to 1 inch of slushy snow possible. High 35 to 40. Wind northeast at 15 to 30 mph decreasing to 10 to 20 mph and becoming north later in the afternoon.
Normal temperatures for Thursday
Sunrise Thursday: 6:11 AM CDT
Sunset Thursday: 8:04 PM CDT