textproduct: Marquette

KEY MESSAGES

- Smoke from upstream wildfires will continue to impact Upper Michigan into this weekend. Air Quality Alerts remain in effect through Sunday. Consider limiting strenuous outdoor activity or remaining indoors when possible.

- A few showers and thunderstorms are possible over the western half of the U.P. on Sunday afternoon.

- Thunderstorm chances begin to increase late Sunday night. Some of the thunderstorms could be strong to severe on Monday as a cold front approaches the region.

DISCUSSION

Issued at 222 PM EDT Sat Jul 18 2026

This afternoon an upper level trough was over eastern Canada extending south into the Great Lakes. The associated surface low pressure was over western Quebec moving east away from the area. A tight pressure gradient was bringing breezy north winds, which were pulling in cooler and drier air. Temperatures were mainly in the 60s north but as warm as 79 in the far south, near Menominee. Cloudiness lingered over the eastern U.P. but was slowly eroding from the north and west. The northerly flow was pulling smoke south into the area with poor air quality over the U.P., along with visibility restrictions and very hazy skies.

As low pressure pushes away from the area tonight and high pressure settles overhead the pressure gradient will relax with winds becoming light. It will be a cool night with temperatures falling into the upper 40s over the interior and 50s close to the lakeshores. Smoke will continue to create poor air quality through the night. An Air Quality Alert has been extended by the Michigan Dept of Environment, Great Lakes, and Energy (EGLE) through the day Sunday.

Sunday looks to be mainly dry but couldn't completely rule out a few showers or weak thunderstorm over the western U.P. as a subtle shortwave moves through the region along with warm air / moisture advection. The chance for showers and thunderstorms will increase late Sunday night and especially on Monday as a vigorous upper level shortwave trough moves into the area. Increasing southwest winds could help push some of the smoke out of the area for Monday. Increasing shear and instability on Monday will bring a risk for storms becoming strong to severe, with the Storms Prediction Center placing most of the U.P. in a slight risk, level 2 out of 5, for severe thunderstorms potential. Temperatures on Monday will rise into the low to mid 80s though there is some uncertainty as lingering smoke, if thick enough, could limit daytime heating. Should this happen the severe thunderstorms threat may also be limited, as less heating will yield less surface based instability.

Expect cooler conditions on Tuesday into Wednesday behind a cold front that will sweep through the area Monday night. High temperatures will be mainly in the 70s with 60s possible close to Lake Superior. It will be breezy on Tuesday with north winds potentially gusting to 30 mph over the land areas and over 45 mph over the Great Lakes. Swim conditions will likely become dangerous on Tuesday for the Lake Superior beaches of Marquette and Alger County. Smoke could also increase again with the northerly flow.

Winds become southerly for Thursday through Saturday with highs in the upper 70s to low 80s as ridging builds into the central U.S. and into the western Great Lakes. There is a chance for showers and thunderstorms on Friday night as a shortwave rounds the northern periphery of the ridge.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 744 PM EDT Sat Jul 18 2026

Canadian wildfires continue to impact all TAF sites with FU/HZ through most of the 0z TAF period. Initially IFR vis holds at all sites, but IWD looks to improve slightly to low end MVFR late tonight. IFR persists into Sunday morning at CMX/SAW with all sites improving to MVFR then VFR later in the day on Sunday as FU/HZ becomes more patchy with increasing SW winds. Model discrepancies remain on that improvement so confidence in timing through out the daytime hours is low.

MARINE

Issued at 222 PM EDT Sat Jul 18 2026

Northerly winds of 20-30 kt over the eastern half of Lake Superior will diminish this evening, falling below 10kt by midnight and backing to the south by early morning. Southwest winds will increase on Monday to 15-25kt as a storm system approaches the lake. Thunderstorms will be possible late Sunday into Monday. Some of the thunderstorms on Monday could be strong to severe with large hail and high winds. Smoke will continue to reduce visiblity though some improvement may occur with the stronger southerly flow pushing smoke back north.

A cold front will sweep across the lake Monday night with gusty northwest winds developing on Tuesday as low pressure deepens over Ontario. NBM continues to show likely gales (50-75% chance) over the eastern half of the lake on Tuesday while the EC remains around 20% or less. Given the strong pressure rises of 6-7 mb/6hr the stronger winds seem plausible. Continue to monitor the forecast over the next few days as details become clearer.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ005-006.

Lake Superior... Dense Smoke Advisory until 8 AM EDT /7 AM CDT/ Monday for LSZ240>251-263>267.

Lake Michigan... Dense Smoke Advisory until 8 AM EDT Monday for LMZ221-248-250.