textproduct: Duluth

KEY MESSAGES

- Smoky conditions early this morning, with some improvement for portions of the Northland today. Additional smoky conditions return this weekend.

- Hot temperatures and increased humidity once again in our southern and western counties today where a Heat Advisory has been issued.

- Two rounds of showers and storms are expected today. Severe weather most likely in the afternoon/evening. A quarter to half inch of rain possible where rain falls, with pockets to 0.75 inches possible right along the International Border.

- Another system will move through early next week with more chances for showers and storms late Sunday into Monday followed by stronger winds and potential near-critical fire weather concerns for Monday and Tuesday.

DISCUSSION

Issued at 216 AM CDT Fri Jul 17 2026

Today - Tonight:

Early this morning, a low-level jet is interacting with weak shortwave energy aloft near and just north of the International Border to kick off scattered showers and storms as noted by regional radar imagery. This area of elevated convection has access to 1000-1800 J/kg of MUCAPE along with effective shear of 30-40 kt. High-resolution models keep the bulk of this precipitation across far northern Minnesota into northwest Ontario through the current overnight through late morning hours today, with the potential for mainly small hail, though isolated quarter size hail can't be completely ruled out. A secondary threat of gusty winds also cannot be completely ruled out, but given the elevated nature of the storms this should be a lesser threat. Rainfall amounts with the morning round will likely be 0.1-0.3" for most locations in far northern Minnesota, though some pockets up to around 0.75" near the International Border are possible where several storms in the cluster move over the same location. While the rainfall would be helpful for ongoing wildfires, it does not appear heavy or widespread enough to mitigate fire concerns. Additionally, there is concern that any lightning from these storms could potentially create more wildfire starts.

Southwest winds develop ahead of a cold front today, which should help push the densest smoke northeastward and lead to clearer skies in our southern and western counties today. This should result in high temperatures climbing into the upper 80s to low 90s for all but the immediate Lake Superior/Arrowhead vicinity and far northern Minnesota. Increasing dewpoints into the mid 60s to low 70s today should also combine with these hot temperatures to produce heat index values in the low to upper 90s. As a result, Heat Advisories have been issued for very late this morning into evening generally along and south of US-2 in northeast Minnesota and northwest Wisconsin.

By the mid to late afternoon, scattered showers and storms are expected to develop along and ahead of the cold front as the capping inversion breaks. This second round of storms should have access to 1000-2000 J/kg of MLCAPE in addition to 30-40 kt of effective shear, modest mid-level lapse rates (6-7 C/km), and strong Downdraft CAPE due to steep low-level lapse rates. This sets a parameter space where storms will be capable of large hail and damaging wind gusts, and a lower-potential threat of a tornado or two (2% chance). While brief downpours are possible with any storm, coverage of rainfall will be limited and heavy rain is not expected. Most of the active convection in the PM hours today will also be south of the active wildfires. Storms and the cold front track southeast into northwest Wisconsin this evening before pushing south of the area tonight. Expect warm temperatures to linger into tonight, with lows around 60-66F.

This Weekend:

In the wake of today's cold front, high pressure moves into the region for Saturday and most of Sunday, bringing dry and primarily sunny conditions, outside of any smoke that is. With winds being out of the northwest tonight and north on Saturday, wildfire smoke is likely to make it's way back into portions of the Northland. We have dropped high temperatures a couple degrees on Saturday (low to upper 80s) to account for decreased solar insolation due to smoke. A shift to southwest winds on Sunday may once again give reprieve from some of the wildfire smoke for portions of the Northland, with high temperatures climbing a few degrees again into the mid to upper 80s. Mostly sunny skies on Sunday gradually see cloud cover increase later in the day ahead of another approaching low pressure system and cold front. While winds won't be overly strong either day, minimum relative humidity each afternoon into the 35-45% range along with hotter temperatures could lead to some elevated fire weather concerns.

Early to Mid-Next Week:

Shortwave energy diving southeast out of the Canadian Prairies Sunday night into Monday will likely bring a return of scattered showers and thunderstorms to the Northland. A strong cold front will move northwest to southeast across the area during this timeframe, and, depending on exact timing, could bring strong to severe thunderstorm potential for portions of the Northland Monday afternoon and evening with a favorable instability/shear combination along and ahead of the cold front. In addition to thunderstorm potential, this also poses concern for additional near-critical fire weather conditions due to strong winds and a 40-70% chance for wind gusts of 30 mph or more with and behind the front on Monday and Tuesday. Drier air behind the front late Monday and on Tuesday could push minimum relative humidities to 30-40% depending on the degree of drying, as well.

Expect high temperatures in the mid 80s to low 90s on Monday and then cooling to the mid 70s to around 80F by the Tuesday- Wednesday timeframe. While temperatures will be more seasonal, there is not a strong signal for widespread or notable rainfall by mid to late next week, so concerns remain for continued drying in the region.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 628 AM CDT Fri Jul 17 2026

Thunderstorms will end in the next hour at INL. Lingering smoke could still affect the terminal for a few hours this morning following the storms. Elsewhere, expect smoke to linger for several hours this morning, but visibility should gradually trend towards VFR as southwesterly winds blow most of it off to the northeast through midday. Winds are expected to become breezy with gusts around 15 to 20 kt. Additional scattered showers and thunderstorms are possible later this afternoon and evening as a cold front passes through. HYR and possibly DLH will have the best chances for seeing any thunder. Winds are expected to switch fairly abruptly from southwest to northwest as the cold front passes through and remain that way for the rest of the period. Smoke will likely remain away from the terminals for the most part tonight, but HYR could see some lingering.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 216 AM CDT Fri Jul 17 2026

A Dense Smoke Advisory remains in effect for all nearshore waters until 7 PM CDT today as widespread wildfire smoke continues to reduce visibilities to 1 nautical mile or less. Northeast winds linger much of the day today, with some afternoon gusts to around 15-20 kt near the head of the Lake this afternoon and 1-2 ft waves. Showers and storms are possible over portions of the North Shore this morning and western Lake Superior late this afternoon and evening. A few of the storms could be strong to severe with gale force winds and large hail. Winds turn northwesterly behind a cold front this evening and tonight with gusts to 10-20 kt, strongest along the North Shore. Winds turn southerly and light for the remainder of Saturday and southwesterly at 5-15 kt on Sunday, with reduced visibility in smoke likely to continue at times when wind directions do not have a southerly component.

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

FIRE WEATHER

Issued at 216 AM CDT Fri Jul 17 2026

Wildfire smoke will continue to linger through tonight. Today, increasing temperatures and southwest winds are expected, but minimum relative humidity stays at 40-60% as dewpoints increase into the 60s to low 70s. Scattered showers and storms are expected this morning in far northern Minnesota into the Arrowhead and on a widely scattered basis along and ahead of a cold front mid-afternoon into this evening. The morning storms could produce small to quarter size hail and erratic, gusty winds. The afternoon/evening storms could produce strong to severe storms with large hail, damaging wind gust potential, and a lower chance for a tornado or two (2% chance). Rainfall amounts for far northern Minnesota will generally be 0.1-0.3", with localized amounts to 0.75" possible near the International Border. Light northerly winds of 5-10 mph with daytime gusts of 10-15 mph and southwest winds of 6-12 mph with 12-18 mph gusts on Sunday combine with minimum RH of 35-45% to potentially produce pockets of elevated fire weather conditions. A strong cold front Sunday night into Monday will veer winds northwesterly with gusts to around 30 mph Monday into Tuesday and minimum RH values of 30-40% Monday and Tuesday, especially behind the cold front. While scattered showers and storms are likely with and ahead of the cold front, widespread heavy rain is not expected and the drier conditions and strong winds behind the front could lead to near-critical fire weather conditions. High pressure also develops into mid-next week, keeping rain- free conditions going for several days next week.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory from 11 AM this morning to 9 PM CDT this evening for MNZ018-025-026-033>038. WI...Heat Advisory from 11 AM this morning to 9 PM CDT this evening for WIZ001>004-006>009. MARINE...Dense Smoke Advisory until 7 PM CDT this evening for LSZ121- 140>148-150.