textproduct: Marquette

KEY MESSAGES

- Rain chances (up to 50%) return to the western UP Thursday evening into Friday morning, along with low thunderstorm chances (20%) along the WI border.

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

DISCUSSION

Issued at 357 AM EDT Thu Sep 3 2026

This early morning, 06Z RAP analysis shows a wedge of 1012 mb surface high pressure extending across the UP, while in Canada GOES water vapor imagery shows that tonight's Quebec low resides just east of James Bay. Local observations show that temperatures have decreased into the 50s (60s if in proximity to a Great Lake), and a look out the window indicates a clear sky with visible stars and a waning gibbous moon.

These clear-sky conditions are expected to change throughout the day today as a pair of shortwaves ride through the region tonight into tomorrow morning. Embedded within WNW'ly gradient flow and grazing the WI border Thursday afternoon, measurable precipitation from this first wave is anticipated in the southern reaches of the UP near Marinette, which may receive up to 0.10" and a thunderstorm or two. The second shortwave arrives in the overnight hours of early Friday morning, traversing the western UP within NW'ly flow. While most of the action from this impulse will manifest south of the UP, CAMs at 24 hours out indicate considerable spread in the exact placement of thunderstorm development. While PoPs range from 20-50% across the UP with up to 0.20" (best and highest chances south and west), a strong thunderstorm can't be ruled out along the WI border or down in Menominee County. Notable with this system is strongly veering wind profile with elevated CAPE; low-end easterly surface winds give way to ~40 kts of WNW'ly flow at 6 km, and some soundings indicate elevated CAPE upwards of 500 J/kg for locations along the WI border.

As the Quebec low progresses eastward, it will be replaced by significant upper-level ridging over the central CONUS, resulting in northwest flow across the Great Lakes for the weekend. High temperatures are expected to remain above-normal in the mid to upper 70s at least through Sunday due to the influence of this ridging pattern. Early next week brings the next best chance for precipitation, with current model guidance indicating a 40-60% chance of at least 0.25 inches of rain by 8am Wednesday, however, uncertainty is still high at this time for the timing and extent of precipitation. Breezy conditions are anticipated as this system moves through. NBM probabilities of wind gusts at or above 40mph are between 30-60% in the Keweenaw, highest on Wednesday in the wake of the cold front.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 119 AM EDT Thu Sep 3 2026

VFR conditions expected through most of the period as surface high pressure gradually builds over Lake Superior and Upper Michigan from the north. Latest guidance continues to hint at patchy fog formation over parts of the UP tonight, bringing in a period of MVFR and eventually IFR restrictions at SAW and possibly CMX 06-12Z. Would expect any fog to quickly dissipate and improve back to VFR Thu morning. Some showers and storms may move towards IWD late in the forecast period. Otherwise, expect light and variable winds tonight to shift out of the east to northeast Thursday, staying below 10kts.

MARINE

Issued at 239 PM EDT Wed Sep 2 2026

Lake Superior: Winds generally remain under 15 kts through Thursday as a low departs to the northeast. High pressure builds over Ontario and troughing deepens over the Northern Plains, resulting in a tighter pressure gradient over the west half of the lake. This yields periods of east to northeast winds of 15-25 kts late Thursday through Friday over the western waters. Stronger high pressure overhead keeps winds light (20 kts or less) lakewide through the weekend, then 20-30 kt winds return next week with a more prominent system lifting to the northeast of Lake Superior. 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 northeast over Manitoba and northwest Ontario 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.