textproduct: Duluth

KEY MESSAGES

- Fairly benign weather today with highs in the 70s and hazy skies due to wildfire smoke aloft.

- Chance for rain and thunderstorms returns late Thursday through Friday. Some heavy rain is possible for portions of the Northland. Cooler temperatures expected, especially near Lake Superior.

- High pressure through the weekend with the next chance of rain and thunderstorms, possibly severe, early next week.

DISCUSSION

Issued at 350 AM CDT Wed Jun 11 2025

Synoptic Overview:

A weak low pressure system is pushing south early this morning, being driven out of the area by a dominant Canadian high pressure. A commanding Canadian high pressure becomes one of the main players over the next couple days, as it slowly shrugs ESE over northern Manitoba and Ontario, playing tug of war with a low pushing up from the four corners region that will be the driver of our next rain maker. This should set up a dry stationary boundary over the Borderlands today, eventually colliding with or being overcome by an approaching warm front from the aforementioned low Thursday into Friday. High pressure then sweeps back around on the backside of this low into the weekend, ushering precipitation chances out.

Today:

For today, the overall synoptic pattern outlined above should result in fairly benign sensible weather for much of the Northland. We'll see afternoon temperatures return into the 70s across the majority of the region with a westerly breeze. Precipitation chances skirt to our south, mostly held at bay by the high pressure to our north. There is still lots of Canadian wildfire smoke aloft, which will likely continue to contribute to hazy skies. As precipitation to our south encourages better mixing, CAMs suggest that some smoke may be able to mix down to the surface mostly south of Highway 2, but with the higher concentrations still south of the Northland.

Thursday-Friday Rainmaker:

Through the day Thursday, we should see precipitation push north, making it into the CWA late Thursday afternoon into the evening. Rain, heavy at times, continues into Friday morning and then starts to push off to the east through the day Friday. The heaviest rain is most likely overnight into Friday morning. Deterministic models show that this warm front should come with warm cloud layers of 10-12kft and a good moisture source with PWATs of 1.2-1.7" running into front- parallel flow allowing for regenerating rain showers and thunderstorms along the boundary. There is some dry air to the north, which could lead to sharp cutoffs in rainfall amounts to the north of where the front sets up. Additionally, partially due to the overnight nature of the system, many models show minimal instability getting as far north as our CWA which would limit the thunderstorm production. Guidance generally shows that an area of heavy rain with 1-2.5" of rain is likely with some rates that could lead to isolated flash flooding and localized amounts in excess of 3".

For as many signs point to heavy rain development, there are an equal number of data pieces that are extremely inconsistent on exactly where this rain falls. Models continue to jump all over in placement, with the most recent trend bringing the heavy rainfall axis back north into the Northland despite an opposite trend just 24 hours ago. Take your pick from your favorite model, and you could see the heaviest rain fall anywhere from Rochester to Duluth. This morning's forecast package brings PoPs and QPF a tad further north than the previous, but generally finds a middle-of-the-road solution amongst all the varying options. This is an event to watch for the heavy rain potential, but at this time confidence in exact placement remains low. Depending on the northward extent of the front, this could interact with a lake breeze boundary coming off of Lake Superior.

This system should also bring easterly winds across the region, cooling temperatures especially for those along Lake Superior where a northeast wind of 25-35mph should bring temperatures down into the 40s and 50s, along with some possible fog as a warm moist airmass hits the big lake.

Weekend and Beyond:

High pressure brings a return to quiet weather for the weekend with temperatures slowly recovering. Southerly flow is expected to make a return into next week which may bring instability and moisture back to the region. This could lead to a chance that severe weather makes a return to the Northern Plains and Upper Midwest but there are still discrepancies on timing, placement, and coverage.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 538 AM CDT Wed Jun 11 2025

Prevailing VFR conditions expected through the TAF period. Light west to northwest winds expected today with some gusts up to 15 knots possible for INL and HIB. Some Canadian wildfire smoke may reach the surface Thursday afternoon and evening near BRD and HYR. There is a 10-20% chance of fog at HYR overnight into Thursday morning but not enough confidence to include it in the TAF at this point.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 350 AM CDT Wed Jun 11 2025

West to northwest winds today should generally remain in the 5-15 knot range, strongest along the North Shore with some gusts up to 18 knots possible. Those winds calm and become northeast overnight into Thursday, picking up momentum through the day. These northeast winds have trended up for Thursday afternoon with some gusts of 20-25 knots possible especially for the head of the lake and a Small Craft Advisory may be needed. Those northeast winds keep up into Friday with areas of 20-25+ knot gusts increasing in coverage and wave heights continuing to build. Winds stay northeast into the weekend but should begin to calm down. Areas of thunderstorms are possible late Thursday into Friday, most likely along the South Shore. Areas of fog may also be possible in that time period.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...None.