textproduct: Duluth

KEY MESSAGES

- Showers and storms this afternoon and tonight. Isolated strong to severe storms capable of 60 mph wind gusts and quarter size hail are possible, especially in northeast Minnesota.

- Patchy dense fog is possible tonight.

- Isolated showers/storms could graze the Brainerd Lakes into northwest Wisconsin Tuesday afternoon, otherwise quiet weather Tuesday-Wednesday.

- Additional chances for showers/storms possible later Thursday into Friday. Lingering showers possible into Saturday.

DISCUSSION

Issued at 158 PM CDT Mon Aug 17 2026

Today-Tuesday: Plenty of sunshine early this afternoon, but instability is building ahead of an area of showers and isolated thunderstorms associated with a cold front in northwest Minnesota. Surface- based CAPE from ~500-1500 J/kg with 0-6 km shear around 30-40 kt is becoming favorable for a few strong to low-end severe storms to develop. DCAPE is surprisingly not as impressive, topping out at 700 J/kg, but that could build a little more. Low-level lapse rates around 8 C/km are quite favorable for some surface-based development. With this, SPC has a marginal risk for severe weather across most of northeast Minnesota this afternoon and evening. With an ongoing cluster of showers and some rumbles of thunder in northwest Minnesota as the catalyst for this afternoon's development, expect this activity to spread east/southeast for the next few hours and potentially kick off additional storms along/ahead of it. Storms may organize into a line, and that's primarily where the wind threat would come from. This does not look to be a widespread severe event by any means, but definitely a few strong to severe storms are possible with widespread general showers and storms. The initial line should pass through northwest Wisconsin through maybe 1-2 AM. Behind that, there could be some redevelopment of some showers along the front (the storms this evening should outrun the front itself). Then, some decaying storms from Montana/South Dakota could pass by to our south (though a slightly more northerly track could clip the Brainerd Lakes into northwest Wisconsin). For most, it should be a pretty quiet day Tuesday with post- frontal northwest flow.

Tuesday night - Thursday: High pressure is expected to be a dominant feature going into Wednesday and Thursday. Light winds and clear skies Tuesday night is looking to bring some pretty chilly lows. Lower 40s and upper 30s are expected especially in the usual cold spots. I wouldn't be surprised to hear of some very isolated frost in the coldest of the cold spots (10% chance). Lows may be chilly again Wednesday night, but increasing clouds may keep temperatures a few degrees warmer than Tuesday night. Highs in the 70s are expected Wednesday-Thursday. Some 80s are likely Thursday east- central Minnesota into northwest Wisconsin.

Thursday late Afternoon - Saturday: There are some hints of a possible upper-level trough that could pass through later Thursday afternoon into Thursday night. A cold front would likely pass through as well going into Friday at some point. Convective parameters still don't look overly impressive for strong storms, but we'll keep an eye on it as that could still change. Any rain chances through Friday look pretty light overall as showers/storms will likely be pretty progressive. Going into Friday night and Saturday, we'll most likely end up with northwest flow. The upper level pattern looks like it will prominently feature a ridge axis to our west with a trough to the east following behind the cold front. Surface high pressure will likely bring us into a pretty quiet weather weekend. There are some hints that some waves of cyclonic vorticity could advect through the region on Saturday attendant with the broader trough to our northeast. Some wraparound showers can't be ruled out in that case.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1242 PM CDT Mon Aug 17 2026

The main hazard this afternoon and evening will be thunderstorm potential as a cold front passes through. Storms are expected to pass over each terminal from northwest to southeast, though thunder is least likely at INL because storms could form more south of there. Strong to severe storms can't be ruled out with strong and erratic winds and small to perhaps quarter sized hail possible. After the storms, winds become northwesterly tonight. Models are in pretty good agreement that there should be some fog developing, especially where it rains. Dense fog is definitely possible for a few hours in the late night/early morning Tuesday period. Expect fog to mix out Tuesday morning, leading to VFR conditions for the rest of the period.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 158 PM CDT Mon Aug 17 2026

Breezy southwest winds are expected to continue from Silver Bay to Grand Portage through this evening. Gusts to 25 mph and wave heights up to 3-4 ft remain possible, especially up near Grand Portage. Winds will decrease later in the evening in general, becoming northwest by early Tuesday morning as a cold front passes through. Showers and thunderstorms are likely along and ahead of the cold front later this afternoon and evening. A few stronger storms capable of producing winds to around 30 kt and small hail can't be ruled out. Winds will become a bit more west to southwest again Tuesday afternoon and winds could gust in the 20-25 kt range up near Grand Portage again Tuesday afternoon. Another Small Craft Advisory might be needed. Winds shift northwest again Tuesday night, then southwest again going into Wednesday.

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

FIRE WEATHER

Issued at 158 PM CDT Mon Aug 17 2026

RH has fallen to around 40% this afternoon for many places in northwest Wisconsin and a few in northeast Minnesota. A few places are into the 30s. Rain is expected later this afternoon and evening, but until then, RH is expected to remain a bit on the low side.

A round of showers and storms is expected through this evening, and while most places will probably see amounts around 0.2" or less, a wetting rain of 0.25" or higher is possible for some. Any locally heavier amounts are expected to be pretty hit-or- miss. Any storms this afternoon and evening in northeast Minnesota could be strong to severe with winds up to 60 mph and hail up to 1" in diameter, but general coverage of strong to severe storms is expected to be isolated. Storms will pass through by around 1-2 AM tonight in northwest Wisconsin with a few lingering showers possible behind overnight.

Tuesday into Wednesday are looking to be mainly dry weather days. RH is likely to tank pretty low into the 30-45% range, especially on Wednesday with high pressure in place. Winds are not expected to be exceptionally strong with gusts to 15 mph for most places and just a few pockets where 20 mph gusts are possible.

Another chance for rain is possible around Thursday into Friday, but amounts will likely be under a quarter of an inch for most places.

See the Fire Weather Forecast product for a more thorough breakdown of fire weather conditions.

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...Small Craft Advisory until 10 PM CDT this evening for LSZ140>142.