textproduct: Marquette

KEY MESSAGES

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

- Isolated to scattered showers and thunderstorms are possible over the western half of the UP tonight.

- Strong to severe thunderstorms capable of producing damaging winds and large hail are possible on Monday PM. Those with outdoor plans should continue to monitor forecast updates.

DISCUSSION

Issued at 154 PM EDT Sun Jul 19 2026

Early this afternoon GOES visible satellite imagery showed smoke over much of the U.P. and Wisconsin. Smoke was beginning to thin over portions of eastern WI, and in general upstream smoke over WI was becoming less extensive in coverage. With southerly flow back over the area temperatures were warmer with sun filtering through the smoke, in the 70s to near 80s. In the upper levels low pressure was located over Alberta and Saskatchewan with a decaying ridge over the upper midwest. Disturbances ahead of the upper low were triggering clusters of thunderstorms over the Canadian Prairies.

The upper level low will push east and become an open wave through Monday bringing increasing chances for showers and thunderstorms. Warm air/moisture advection and increasing instability over the region will help support thunderstorm development tonight into Monday morning. CAMs are wanting to bring ongoing convection over Ontario south through the west-central part of Lake Superior and possibly into the Keweenaw this evening but this is more uncertain as the environment will still be marginally supportive of precipitation at that time. Strong to severe thunderstorms are expected over the Dakotas today but these should be decreasing in intensity as they push east, reaching the western U.P. during the early morning hours. Most likely these storms will stay below severe levels as they move across the U.P. during the morning hours.

Behind the showers and storms clouds are expected to decrease on Monday late morning and afternoon resulting in further destabilization of the atmosphere. This will bring an increased threat for thunderstorms by late afternoon and evening as the cap weakens and the approaching shortwave and upper level jet provide large scale ascent. Shear (40kt+), instability (~2500 J/kg) and increasing SRH will be sufficient for some of these storms to become severe with large hail and damaging winds being the main threats though could not rule out a few tornadoes given the expected increasing SRH. SPC has all of the U.P. in a slight risk (level 2/5) and the western U.P. in an enhanced risk (level 3/5). Any thunderstorms that develop during the late afternoon may be more isolated/discrete supercells but will likely build upscale into a linear system as a front pushes through the area during the evening hours. Please keep up with the latest forecasts and have a way to receive weather alerts Monday and Monday night.

Strengthening southerly winds on Monday will result in building waves over Lake Michigan, as high as 7 feet by late afternoon along the beaches of Schoolcraft County. This will bring a high rip current threat and dangerous swim conditions.

Expect cooler conditions on Tuesday into Wednesday behind the 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.

The area remains under northwest flow aloft into the early part of the weekend with a ridge building back over the central U.S. This will bring the opportunity for showers and thunderstorms as weak disturbances in the flow push across the U.P. Afternoon temperatures will be seasonable, upper 70s to low 80s, with lows in the 50s. Temperatures will warm to the mid 80s on Sunday as the ridge shifts east over the Upper Great Lakes.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 231 PM EDT Sun Jul 19 2026

High pressure will prevail today across Uppper Michigain. However, with the TAF sites still under dense wildfire smoke, visibility restrictions will be the main impact. Diurnal mixing and southwest wind gusts up to 20 kts have been slow to improve conditions so far this afternoon with both SAW and CMX at IFR and MVFR levels, respectively. In addition, some showers/thunderstorms may attempt to reach the far western UP and Keweenaw late tonight and SAW tomorrow morning, so will continue mention of prob30s at all TAF sites for this scenario.

MARINE

Issued at 154 PM EDT Sun Jul 19 2026

Visibilities will continue to be reduced across much of the lake due to widespread smoke through tonight. Some fog may also be mixed in with the smoke at times. Light wind today give way to increasing southwesterly winds tonight into Monday, reaching 20-30kt by Monday morning, strongest over the western half. This should help erode the smoke and while it will remain hazy expect visibilities to improve. Will keep the dense smoke advisory in effect through tonight but expect we will be able to expire it Monday morning. Thunderstorms will also be possible tonight through Monday. Some of the storms could be strong to severe Monday afternoon and evening with large hail and high winds.

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. Given the strong pressure rises of 6-7 mb/6hr and modest cold air advection for this time of year gales seem plausible. Winds of 20-30kt will linger Wednesday morning over the eastern part of the lake but expect winds to fall below 20kt by evening with light winds for Thursday and Friday. Continue to monitor the forecast over the next few days as details become clearer.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement from Monday morning through Monday evening for MIZ014.

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.