textproduct: Marquette

KEY MESSAGES

- Ongoing showers and storms will pass out of the UP by mid-morning, with rain chances (up to 40%) lingering in the western UP through this evening.

- Above-average temperatures will persist through Labor Day Weekend, with high temperatures in the mid to upper 70s.

- Dry conditions prevail Saturday and Sunday, and precipitation chances increase throughout the day on Monday to 50% in the west by evening.

DISCUSSION

Issued at 408 AM EDT Fri Sep 4 2026

Radar imagery this morning shows multiple clusters of storms making their way across MN, WI, and MI as a shortwave moves through the region. For the UP, the first batch is currently over the central UP while becoming increasingly disorganized, but not after dropping large swaths of 0.3-1" of rain per MRMS (with both more and less in some locations). Driven by a predominantly westerly 300-850 mb mean wind and aided by upper-level divergence, this first batch continues to move toward cooler air in the low 60s and dewpoints in the high 50s, leaving the region of higher instability to its south. A few stronger cells have popped up, but so far have stayed sub-severe with potential for winds to 30 kts and small hail.

A second round of convection is currently passing Duluth, with parts of this line bound east. This long-lived group has evolved over the past few hours from multiple tight segments into an elongated line. Its path so far has largely followed a NW-SE MUCAPE gradient running from northern MN toward Green Bay and from there toward lower MI (values of 1000 J/kg near MI-WI border and 2000 J/kg in northern WI per SPC Mesoanalysis). While southern sections of this line may move into higher instability areas in northern WI and reinvigorate, the northern portions may detach and head east toward the UP. Should this occur, any cells will be moving into cooler, overturned air from the previous storms. While it's possible this cooler air will dampen any convection, outflow boundaries residing in the air may also serve to initiate uplift. Given proximity of high MUCAPE values and up to 50kts 0-6 km shear, will continue to monitor radar as storms evolve. Though severe weather is not expected, a stronger storm or two could occur, most likely near the WI border.

Storms and rain are expected to clear out by late morning, though some low-end precipitation chances (<40%) linger over the western UP through this evening. Rainfall from this is expected to be less than a tenth of an inch. Given cloudiness today, high temperatures today will reach into the mid to high 70s, with mostly light, easterly flow.

Broad upper level ridging over the central CONUS continues to dominate the pattern through the holiday weekend. As such, temperatures will remain above normal into next week with daytime highs residing in the mid to upper 70s to perhaps the low 80s in a few locations each day. The forecast looks to be mostly on the dry side through the weekend, but precipitation chances increase again early to mid next week as ridging starts to flatten out and makes way for a potentially stronger system to pass through the region. Details are still sparse, but NBM depicts a 50-70% chance for at least a quarter inch of rain across the UP by early Wednesday, and also depicts a 40-70% chance for wind gust of 40 mph or greater over a wide swath of Lake Superior and the Keweenaw in the same time frame. Will continue to monitor this potential as details hopefully start to come into better focus in the coming days.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 815 AM EDT Fri Sep 4 2026

Ongoing showers and thunderstorms are moving through the UP this morning and leaving low cloud formation in their wake. Expect LIFR to MVFR conditions at all three sites during the majority TAF period. At IWD, expect ceilings to remain mostly LIFR throughout the day, lifting to MVFR for a brief window this afternoon. Given moist low-levels, light winds at IWD increase the likelihood of fog formation overnight tonight. Showers are on their way out of CMX, though low ceilings will linger and winds remain elevated out of the east. Another batch of showers is inbound toward SAW, leading to patchy IFR ceilings for another few hours. Ceilings eventually lift toward the end of the day, but northeast flow this evening could drive fog formation at SAW.

MARINE

Issued at 300 PM EDT Thu Sep 3 2026

Lake Superior: High pressure building in from northern Ontario as troughing deepens over the Northern Plains will tighten the surface pressure gradient over the western half of the lake this evening, yielding east to northeast winds of 15-25 kts tonight through Friday. Stronger high pressure building overhead keeps winds light (20 kts or less) lakewide during the weekend, then 20-30 kt winds return next week with a more prominent system lifting to the north of Lake Superior, with the NBM depicting a 40-70% chance for gale force gusts at this time. Wave heights are largely expected to remain at 3ft or less through the weekend, increasing to 2-6ft as winds increase early next week.

Northern Green Bay and northwestern Lake Michigan: Winds generally remain 15 kts or lower through this weekend as high pressure slowly builds overhead. A more prominent system lifting north of the region early next week increases winds to around 15 kts with gusts up to 20- 25 kts. Wave heights are expected to remain below 1ft through the weekend, increasing to 2-4ft with increasing winds early next week.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... None. Lake Michigan... None.