textproduct: Marquette

KEY MESSAGES

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

- Scattered rain showers and thunderstorms will continue into tonight. A few storms could be strong to severe this evening.

DISCUSSION

Issued at 404 PM EDT Fri Jul 17 2026

Afternoon RAP analysis shows upper level flow pivoting to a more westerly orientation across the Upper Great Lakes as the persistent ridge dominating the central CONUS is gradually flattened out by the influence of strong troughing over eastern Canada. An approaching shortwave trough is apparent in GOES water vapor imagery over Manitoba, with an attendant surface low analyzed from northern MN into NW Ontario bringing welcome rainfall to the upstream wildfires today. Closer to home, one batch of showers and thunderstorms is exiting the eastern UP along a pseudo warm front while another moves over the Keweenaw Peninsula from western Lake Superior. Gusty southwest winds have helped to clear some of the near surface smoke out of parts of the western UP as seen on visible satellite, yielding a rather stark temperature gradient ranging from the upper 80s along the WI state line to the upper 60s in the Keweenaw and through much of the eastern UP. As a result, SPC mesoanalysis depicts 2000+ J/kg MUCAPE values over parts of the western UP, dwindling to 500-1000 J/kg with lingering CIN across the east. Would thus expect the greatest potential for strong to severe storms to be found in the west as a surface cold front arrives later this evening, but also can't rule out a few stronger storms in the east given effective shear values of 40 kt and ample upper level support from the approaching shortwave. Any showers and thunderstorms will remain capable of producing locally heavy rainfall through this evening as PWAT values continue to reside above 1.5 inches.

Showers and thunderstorms will taper off from west to east overnight as the system departs the area, with any lingering showers mostly ending across the eastern UP by mid morning. Smoke models continue to indicate improved conditions through Saturday morning in the wake of the departing cold front, but also show another round of heavier smoke potentially descending upon the UP Saturday afternoon in renewed northwest flow. The Michigan Dept of Environment, Great Lakes, and Energy (EGLE) has extended the statewide Air Quality Alert through Saturday. It is reasonable to expect at least some smoke impacts into the early part of next week given continued northwest flow, though hopefully at lower concentrations than in recent days given today's rainfall over the upstream wildfires. Aside from the lingering questions about smoke, the forecast otherwise looks relatively benign through much of next week as the region settles back into northwesterly flow with temperatures near seasonal norms. There is increasing confidence in another system bringing another shot of widespread rainfall to the area on Monday. SPC has also introduced a 15% probability for severe weather for the area on the Day 4 convective outlook, so will have to keep a close eye on thunderstorm potential early next week as well.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 129 PM EDT Fri Jul 17 2026

Widespread smoke and scattered -shra/tsra are making for a challenging aviation forecast. Smoke has generally resulted in IFR and periodic LIFR vsby so far today at the CMX and SAW. IWD had improved to MVFR vsby as southwest winds brought in cleaner air. Guidance suggests the smoke will continue to retreat to the north with southerly flow, bringing vsby to MVFR and VFR later the evening. Meanwhile, a few rounds of showers and thunderstorms will move through the region, mostly handled with PROB30s. A few of the thunderstorms could be strong to severe, with large hail, damaging winds and frequent lightning. Late tonight the winds will shift northwest behind a cold front with a few hour period of MVFR cigs. The northerly flow will transport smoke back to the south. The highest confidence in smoke increasing on Saturday is at CMX, indicated with MVFR vsby through Saturday afternoon.

MARINE

Issued at 404 PM EDT Fri Jul 17 2026

Dense Smoke Advisories remain in effect for all of Lake Superior through Saturday morning and for northern Lake Michigan/Bay of Green Bay through midnight as wildfire smoke from Ontario and MN continues to drift over the region. Expect visibility to continue to fluctuate below 1 nm at times. Will continue to evaluate whether these headlines need to be extended in future forecast cycles, but latest smoke guidance suggests improving conditions over Lake Michigan tonight and at least the western half of Lake Superior by Saturday morning. Gusty southerlies upwards of 20-25 kts in the eastern half of the lake increase this evening ahead of the approaching low pressure system. This system moves across the lake tonight, shifting winds to the NW behind the a cold front overnight through daybreak tomorrow. Showers and thunderstorms may be strong to severe along the cold front this evening. NW winds 15-25 kts with a few gusts to 30 kts in the east half linger on Saturday, with wave heights between 3-5 ft expected along the eastern Superior shorelines. Have hoisted a round of small craft headlines for the eastern Superior nearshores and northern Lake Michigan/northern Bay of Green Bay on Saturday as a result. Winds fall back below 15 kts lakewide Saturday night. Stronger winds are possible again early next week, with ensembles even hinting at gales over the eastern half of Lake Superior late Monday into Tuesday in the wake of the next system on Monday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement from Saturday morning through Saturday evening for MIZ005-006.

Lake Superior... Dense Smoke Advisory until 6 AM EDT /5 AM CDT/ Saturday for LSZ162-240>251-263>267.

Lake Michigan... Dense Smoke Advisory until midnight EDT tonight for LMZ221-248- 250.