textproduct: Marquette

KEY MESSAGES

- Scattered showers (30-60% chance) and isolated thunderstorms (20% chance) move west to east across the UP today. Strong to severe storms are not expected and rainfall amounts will be limited.

- Wind gusts near 25 kt will result in hazardous conditions to small craft along the western shore of the Keweenaw to the WI border through this afternoon, as well as for the nearshore zones of Lake Michigan this afternoon and evening. There is a high risk of rip currents for the Schoolcraft County beaches today.

- Near-normal temperatures today and Wednesday give way to increasing temperatures the latter half of the work week.

DISCUSSION

Issued at 300 AM EDT Tue Aug 4 2026

Early this morning, water vapor imagery and RAP analysis reveal broad troughing over the Northern Plains and into the Upper Midwest, with an embedded shortwave pivoting northeastward out of the Dakotas. At the surface, an associated cold front is directed from just west of Lake Nipigon southwestward through MN, with a batch of showers and storms reaching the western shores of Lake Superior. Closer to home, skies remain mostly clear over the UP, though cloud cover is beginning to thicken over the west. Temperatures hover in the 60s across most of the area, but are still in the lower 70s across the far western UP and the Keweenaw; temperatures should only fall a few more degrees tonight with the warming airmass and increasing cloud cover from west to east.

Showers and storms finally reach the western UP towards daybreak as the cold front sweeps through, but CAMs continue to indicate that they quickly diminish with eastward as they encounter a dry and stable airmass over the central UP. However, surface-based destabilization ahead of the front, over the eastern UP, will help convection ramp up again there during the afternoon as the front continues its eastward trek. MUCAPE generally stays below 750 J/kg, so any storms are not expected to be strong/severe. That said, there is some question as to whether surface based instability can even develop given model soundings depicting a warm nose around 800-850 mb, so coverage of storms is expected to remain isolated at best. Highs range from the low 70s west, where FROPA happens earliest, to low 80s east.

Weak ridging builds in the wake of the front for Wednesday, setting up a dry and seasonable day with highs mainly in the 70s. Another shortwave trough rotates through Thursday, but with a lack of any notable moisture, another dry day is expected. Temperatures are expected to be on a general warming trend late week into the weekend as low-level southwesterly flow develops. Thunderstorm potential enters the picture again by the weekend as strong quasi-zonal flow develops between Hudson Bay low and Four Corners high. Unclear whether the reservoir of greater instability will get this far north.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 129 AM EDT Tue Aug 4 2026

VFR conditions look to prevail the rest of tonight as high pressure gives way to a cold front making its way eastward towards Upper Michigan, eventually arriving this morning. While some -SHRA could (20-40% chances) be seen over mainly the IWD and CMX during the morning hours, we could see -SHRA by SAW as soon as 17Z (~20% chance as of the current forecast), with higher chances of precipitation (including around 20% chances of -TSRA) coming after 18Z. While the cold front is passing through, MVFR ceilings are expected at IWD (45- 65% chance) and possible at CMX/SAW (30-50% chance). In addition, with the front approaching tonight, expect a period of LLWS tonight for CMX/IWD. Expect generally southwesterly winds to shift west to northwest behind the front, with wind speeds highest around the time of the front's passage.

MARINE

Issued at 300 AM EDT Tue Aug 4 2026

Southerly wind gusts to around 20-25kts become common across the lake this morning ahead of an approaching cold front. This has also brought thunderstorms to northern MN, which are beginning to move over far western lake Superior. Storms diminish into the pre-dawn hours, but may redevelop over the east half of the lake this afternoon into the evening. Winds shift westerly behind the front this afternoon and gradually decrease, remaining below 20kts through midweek. Winds then pick up out of the south Friday, gusting to near 20-25kts before decreasing Saturday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement from 10 AM EDT this morning through this evening for MIZ014.

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