textproduct: Duluth

KEY MESSAGES

- Showers and thunderstorms through this evening and early overnight. A few strong to severe storms are possible between about 3 PM and 10 PM. Large hail is the main threat, but some gusty winds cant be ruled out.

- Fog with areas of dense fog possible tonight into early Friday morning.

- Lingering isolated showers and possibly a storm or two are possible Friday.

- Mostly sunny weather with seasonable temperatures are expected this weekend into early next week.

- Additional shower/storm chances arrive around Monday night into Tuesday night.

DISCUSSION

Issued at 137 PM CDT Thu Aug 20 2026

The main story for this afternoon and evening will be thunderstorm chances. As of the early afternoon, a broad swath of clouds with embedded showers and storms cover much of the Northland with some pockets of clearing. The current showers/storms are associated with the warm sector of a low pressure system, which is centered near the Canadian Border over northwest/north-central Minnesota. The low is expected to move southeast this afternoon, and there is an area of clearing out near Upper/Lower Red Lake that could be a focus for additional thunderstorm development this afternoon. Some surface-based CAPE on the order of 1-2 kJ/kg is supportive for some strong/severe storms. Theres some modest ~20-30 kt effective shear and generally less than 700 J/kg of DCAPE. If storms fire this afternoon, they will likely be focused in the vicinity of the cold front, affecting areas roughly along the US-2 corridor and south, and maybe up to the Iron Range. Hail looks to be the primary threat, and we could see some quarter size to maybe ping pong ball size hail in a few storms. Some gusty winds or perhaps a very brief tornado cant be totally ruled out (~2% chance) with at least marginally favorable southwesterly winds and low-level shear ahead of the cold front, but there does look to be a general mismatch where the best shear early this afternoon may not coincide with the best instability in the later afternoon and evening such that the tornado risk is low. The strong/severe storms may develop around 3 PM this afternoon and linger as they move into northwest Wisconsin through about 9 or 10 PM. They should weaken pretty quickly after sunset (at least as far as the severe threat goes), though they wont dissipate completely as they move east with the front. After the front, for the rest of the night, isolated pop-up showers cant be ruled out with a little lift aloft and moisture remaining. An overall drying trend is expected though.

On Friday, a secondary cold front and cyclonic vorticity advection aloft may trigger some afternoon showers and perhaps some storms. At this point, severe weather isnt expected with pretty much straight northwest flow expected, but we could see just under 1 kJ/kg of MUCAPE in the afternoon that could support a few non-severe storms. Otherwise, skies are looking partly cloudy in the afternoon after mainly overcast skies during the morning with fog (possibly dense for some areas, especially around the head of Lake Superior with a period of northeast winds likely later tonight into Friday morning). Isolated showers could linger into Friday evening.

Going into the weekend, broad ridging across the western CONUS with surface high pressure over Manitoba/North Dakota will bring us some slightly cooler weather with northwest flow. The weather is looking very quiet and dry over the weekend. The only main concern will be some lower RH values falling a bit below 40%, especially on Sunday, which could lead to some slightly elevated fire weather concerns. But, winds will be pretty light Sunday/Monday when the driest conditions arrive, so even this is a small concern.

Next week, another low pressure system may bring some warm air advection-induced showers and storms Monday night into Tuesday. A potential low pressure system may take a similar track as today's low, bringing another cold front through sometime around Tuesday evening/night.

For the rest of the week, generally northwest flow aloft should keep us in a quiet weather pattern to end the week.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1240 PM CDT Thu Aug 20 2026

Main aviation challenges this period are shower and storm chances and their impacts on restrictions through the first half of the period followed closely by restrictions due to fog developing after midnight tonight. Ongoing storms will be just east of BRD heading towards HYR, but additional storm development is forecast later this afternoon into this evening and is handled largely by prevailing SHRA with PROB30 TSRA. After these depart, light winds and the recent rainfall will allow fog to form with continued growing confidence in IFR/ LIFR or lower restrictions. Additional timing refinements will be needed for the fog and low ceilings as they abate Friday morning.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 137 PM CDT Thu Aug 20 2026

Expect scattered showers and thunderstorms through this evening. Severe weather is not expected, though a stray storm or two could produce some hail or gusty winds. Otherwise, a cold front will pass through and then high pressure. Winds are expected to become light and variable into Friday. Winds become predominantly northwesterly going into Saturday with some 15-20 kt gusts, highest along the North Shore. A brief period of northeasterly winds is likely on Sunday. Aside from this evening's storm chances, hazardous weather is not anticipated Friday through Sunday.

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

FIRE WEATHER

Issued at 138 PM CDT Thu Aug 20 2026

Severe thunderstorms are possible today mainly south of the Iron Range from late afternoon to sunset today. The main hazard would be large hail to 1.5 inch in diameter...50 mph gusty and erratic outflow winds though cannot be ruled out either. Any rainfall would be localized from where these isolated storms pass over. South winds today shift to northerly behind a passing cold front tonight. For Friday daytime, isolated non-severe thunderstorms could bring cloud to ground lightning and gusty, erratic wind gusts to 30 mph. These Friday daytime shower chances generally taper by late evening tomorrow. No rainfall is expected this weekend. Northwest winds sustained around 10 mph gust to 20 mph Saturday before becoming light and variable Sunday. Next week for Monday night into Tuesday there is the next thunderstorm chance after Friday evening.

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

DLH WATCHES/WARNINGS/ADVISORIES

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