textproduct: Duluth

KEY MESSAGES

- Patchy fog, occasionally become locally dense, is expected to dissipate after sunrise. Cloud cover will be increasing later this morning into the afternoon.

- Showers and thunderstorms arrive this afternoon and evening along a cold front. A few storms may be strong to severe, especially in the Brainerd Lakes area. Potential hazards include damaging winds up to 60 mph and large hail up to 1 inch in diameter.

- Dry and cooler weather is forecast for Tuesday into Wednesday, with additional rain chances and slightly warmer temps late in the workweek.

UPDATE

Issued at 422 AM CDT Mon Aug 17 2026

Mostly clear skies allowing for diurnal cooling combined with light winds has produced patchy fog early this morning. Visibility has been trending slightly lower since the previous discussion update, with isolated areas of 1/2 mile visibility occasionally occurring. Will continue to hold off on issuing a Dense Fog Advisory this morning due to the dense fog coverage being too isolated and duration being too intermittent. Fog is still expected to dissipate just after sunrise this morning as diurnal heating begins.

The forecast for this afternoon is still on track with the previous update. Timing for showers and thunderstorms developing along an approaching cold front is still expected to be the afternoon into the early evening, which will coincide with peak diurnal heating. The southwestern portion of the CWA remains under a Marginal Risk (Level 1 out of 5) Outlook from SPC today, with a small northward expansion of the Marginal Risk occurring this morning. Potential severe hazards will be damaging winds up to 60 mph and large hail up to 1 inch in diameter.

Following the cold frontal passage tonight, cooler temperatures filter into the CWA for Tuesday into Wednesday. Frost is not anticipated on Tuesday night into early Wednesday morning, but expect chilly low temperatures in the 40s with a few upper 30s possible. The forecast for the latter half of the week remains on track since the previous forecast update.

DISCUSSION

Issued at 155 PM CDT Sun Aug 16 2026

Plenty of clouds with a few embedded sprinkles is the story of this Sunday. Drier air is filtering in from the northwest with a surface high moving in from the west. Therefore, expect gradually clearing skies this afternoon and mostly clear skies overnight. We will probably get some fog to develop with good radiational cooling conditions. Models are pretty solid on having fog in the usual low-lying inland areas. The probability for visibilities less than 1 mile are generally 20% or less, so we will probably see some patchy dense fog, but perhaps not enough coverage to warrant any Dense Fog Advisories. Expect fog to lift/mix out just after sunrise Monday morning.

Monday afternoon into Monday night, another cold front is expected to make its way through from northwest to southeast. We'll have sufficient moisture for some thunderstorms with PWATs in the 1-1.5" range. Good synoptic support for lift with the front itself and an upper-level trough aloft. Convective parameters are so-so for any strong/severe storms. The timing of this has trended earlier such that we may catch the peak diurnal heating Monday afternoon and end up with ~1000 J/kg or so of MUCAPE, at least in northeast Minnesota. Not much for low-level directional shear with southwest flow expected ahead of the front. Some drier air aloft ahead of the front could produce a small risk for strong wind gusts. All said, we'll be looking at widespread showers and storms likely Monday afternoon and night, generally weakening a bit as they move into northwest Wisconsin. A few storms could be on the strong side with some small hail and gusty winds, and a stray severe storm can't be ruled out with low-end strong winds or quarter size hail being the main threats.

Expect the front to be out of here Tuesday morning, leaving us with northwest flow and some slightly cooler temperatures (highs in the 70s). Tuesday night might be on the chilly side with lows in the 40s likely and perhaps some stray upper 30s not out of the question for the usual cold spots. High pressure sticks around into Wednesday, keeping the weather quiet. Southerly return flow will likely develop Thursday, and we'll be watching for another cold front to be making its way here by around Friday. We could see another round of showers and storms with this. At this time, convective parameters look rather dull for anything strong/severe, but that could change.

The pattern is looking very pre-fall next weekend with northwest flow following the cold front. Some lingering instability showers can't be ruled out Saturday, but otherwise the weather looks pretty quiet. One might be tempted to call this fall-like weather, but with temperatures still looking to be in the 70s to around 80 for highs, it should still be feeling more like late-summer weather.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 626 AM CDT Mon Aug 17 2026

Patchy fog will be clearing over the next couple hours as daytime heating begins and west-southwest winds increase. A cold front will be sweeping through this afternoon and evening, bringing a line of scattered to widespread showers and thunderstorms. A few storms may become strong, especially around the Brainerd Lakes, capable of producing small hail and gusty winds. After the rain exits tonight, another round of patchy fog will be possible as winds ease overnight.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 422 AM CDT Mon Aug 17 2026

Breezy southwest winds ahead of a cold front are expected this afternoon along the North Shore. The Small Craft Advisory that was in effect from Grand Marais to Grand Portage has been expanded to now include nearshore waters from Grand Marais to Silver Bay, as there is the potential for wind gusts to 25 knots for several hours this afternoon.

Showers and thunderstorms arrive along the aforementioned cold front this afternoon and evening, although severe thunderstorms are not expected. Expect winds to shift to the northwest tonight following the cold front, with winds generally trending lighter heading into mid-week as high pressure builds.

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

FIRE WEATHER

Issued at 422 AM CDT Mon Aug 17 2026

Clear skies will start off today, with southwest winds gusting 15 to 20 mph this afternoon ahead of an approaching cold front. Expect cloud cover to increase from west to east through the day, with northwest WI seeing the driest min RH this afternoon in the 33-39% range due to clouds not arriving until later in the day. Scattered to widespread showers and thunderstorms will be moving through this afternoon and evening, with wetting rains of 0.25" or greater being hit or miss under individual thunderstorm cores. A few storms may become strong to severe, especially in north-central MN, with gusty and erratic wind gusts up to 60 mph and hail to 1" in diameter being primary hazards.

Winds shift to the northwest tonight and high pressure builds on Tuesday into Wednesday, bringing cooler temperatures and drier min RH for mid-week. While critically dry min RH is not anticipated at this time, areas of min RH as low as 30% will be possible each afternoon from Tuesday through Thursday. Additional chances for showers and thunderstorms arrive late Thursday into Friday as another cold front moves into the area.

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 from noon today to 10 PM CDT this evening for LSZ140>142.