/Issued 7:27 PM CDT, Wednesday, June 13, 2018/
The start of what could be a few days with occasional thunderstorms begins late Thursday night with scattered showers and thunderstorms expected to move through parts of northeast Minnesota and northwest Wisconsin from late Thursday night into Friday morning. Main threats out of this activity include lightning, heavy downpours and possibly some hail and or gusty winds with the hail and gusty wind threat most likely in north central and east central Minnesota and points west the way it looks now.
Still seeing a consistent signal per model guidance for some hefty rainfall totals across the Northland beginning Thursday night and continuing through the weekend. Flooding could become an issue for some if these rainfall totals verify.
12z European Ensemble model from June 12, 2018
High pressure is over Iowa early this evening, this high brought dry weather to the Northland today under mostly sunny to partly cloudy skies. Highs were in the 70s to lower 80s.
Quiet tonight under clear to partly cloudy skies, lows will be in the 40s and 50s. Highs Thursday in the 70s to lower 80s but turning cooler near Lake Superior as easterly winds develop and increase by the afternoon.
High pressure to our south this evening will position itself southeast of the Northland starting Thursday while low pressure heads into the northern Plains/western High Plains region. Still not terribly humid Thursday with dew points generally in the 40s and 50s, but that will change starting Friday with dew points climbing into the 60s and perhaps even into the 70s, and this humid/tropical feel should persist through the weekend the way it looks now.
A warm front approaches from the west/south late Thursday night with an increase in elevated CAPE along with a healthy low level jet which will advect deeper moisture and instability into our area. We should see some showers and thunderstorms develop across the Northland late Thursday night into Friday morning.
Additional rounds of showers and thunderstorms are then expected for Friday, Saturday and Sunday. There should be some breaks mixed in as well so I don’t think will be dealing with all day rains given the type of pattern we’re heading into. Thunderstorms that do develop from Friday through Sunday will have plenty of instability and moisture to tap into. CAPE 1500 to around 4000 j/kg, PWATS 1.50 to 2.20 inches, dew points 65 to 75 degrees. A frontal boundary should become nearly stationary over the upper Midwest this weekend, possibly fluctuating a little north or south at times. This front combined with possible disturbances lifting southwest to northeast over the area should provide the necessary lift to generate clusters of showers and thunderstorms near and north of the aforementioned stationary front.
High temps Friday through Sunday are forecast to be in the 70s and 80s but a lake wind could keep temps in the 50s and 60s near Lake Superior including for Grandma’s Marathon Saturday morning, it still looks rather humid though even near Lake Superior this weekend.
Forecast for Duluth and Superior
.Tonight… Mostly clear. Low 51 to 56. Wind west to southwest at 5 to 15 mph.
.Thursday… Partly cloudy. High 73 to 78 but turning cooler near Lake Superior. Wind becoming east at 5 to 15 mph with gusts to 20 mph during the afternoon.
.Friday… Partly to mostly cloudy. Showers and thunderstorms possible. High 70 to 75 but cooler near Lake Superior. Wind east at 10 to 20 mph.
Normal Temperatures for Thursday
Sunrise Thursday: 5:14 AM CDT
Sunset Thursday: 9:04 PM CDT