textproduct: Marquette

KEY MESSAGES

- Showers and thunderstorms return to the western half today, spreading east tonight into Tuesday.

- Temperatures trend hotter this week, with widespread 90s possible mid to late week.

- Strong to severe thunderstorms are becoming more likely on Wednesday. Continue to monitor the forecast for additional details.

DISCUSSION

Issued at 340 AM EDT Mon Jun 8 2026

Early morning GOES water vapor imagery and RAP analysis places the axis of a stout upper level ridge just east of the UP, extending from eastern Ontario down through Lake Huron and into the Ohio River Valley. A shortwave trough is riding up the western side of the ridge into the Upper Mississippi River Valley, with associated showers and a few embedded thunderstorms noted upstream over WI and MN on regional radar imagery as broken mid level cloud cover streams into the UP ahead of this activity. Expect these showers to start to spread into the far western UP after daybreak as the shortwave continues to lift northward towards the Upper Great Lakes. Isentropic ascent in tandem with more than ample moisture (PWATS 1.75-2", near the max of NAEFS PWAT climo for this time of year) will be the driver for scattered shower/t-storm development that encompasses the western half of thew UP through this afternoon and then slowly spreads east tonight into Tuesday. CAM ensemble 24 QPF spread ending Tuesday afternoon still suggests mean amounts around 0.25", though given the scattered nature of precip, high PWATs, and meager MUCAPE, thinking that the precipitation footprint will not be so uniform across the area. Areas that receiving multiple rounds of showers with embedded thunderstorms could easily collect upwards of 1-1.5". No severe storms are expected at this time given meager shear and instability. Precip should largely clear the area by Tuesday afternoon, leaving room for a brief period of quiet weather save for lake breeze driven afternoon precipitation potential.

A more potent shortwave is forecast to lift through High Plains on Wednesday, developing a strong surface cyclone that works into Ontario through the afternoon, placing much of the Upper Midwest and Northern Great Lakes in a ripe warm sector. Ensemble joint probability of at least 1500 j/kg of sfc based instability and deep layer shear >30 kts reaches 40-50% across the western UP and Lake Superior Wed PM, suggesting possible strong to severe storms capable of producing large hail and gusty winds. Exceptionally high PWATs also suggest the potential for flash flooding. At this time, SPC continues to highlight a severe risk for most of MN, WI, and the western UP as we move into Day 3. Outdoor recreationists should continue to monitor forecast trends!

In addition to the increased moisture, warm temperatures, possibly the warmest experienced so far this early summer, are expected into the midweek. The NBM continues suggesting a high chance (60-90%) of surface temps exceeding 90F across the interior west and central Wednesday/Thursday. However, these temperatures may be inflated by the ensemble's bias correction, which was been warmer than observed recently. Non-bias corrected ensembles such as the LREF, comprised of other global ensembles, suggests a low <30% chance for sfc temps reaching 90F this far north. Regardless, its becoming increasingly likely that the warmest (and most humid) airmass of the warm season so far is ahead this week, so individuals with heat sensitivity should prepare as necessary!

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 138 PM EDT Mon Jun 8 2026

Cloud cover and precipitation chances will continue to increase from west to east this afternoon in association with a low pressure system. This will result in VFR conditions eventually deteriorating to MVFR at IWD and CMX later this afternoon. IFR conditions will be possible at times as showers with embedded thunderstorms spread across the western UP. For SAW, VFR conditions are expected into tonight, then conditions will deteriorate after 06z Tuesday as showers move into the area. Expect conditions to go down to IFR at all terminals tonight after 09z Tue. Also, cannot rule out LIFR/VLIFR conditions at all terminals early tomorrow morning.

MARINE

Issued at 340 AM EDT Mon Jun 8 2026

Going forecast remains on track with overall light winds <25 kts lake wide through the first half of the week. Could see a few gusts getting up around 25 kt on the east side of the Keweenaw this afternoon, but thinking these should be sparse enough in coverage and with wave heights only building to around 1-3 feet to forego any headlines today. Some strong to severe thunderstorms are possible Wednesday P.M., largely across the western half. Continue to monitor the forecast for ongoing trends and updates. The second half of the week is slated to be a bit windier as forecast guidance continues to trend several systems into the Northern Great Lakes, bringing additional chances for showers and thunderstorms as well as periods of winds >25 kts.

MQT WATCHES/WARNINGS/ADVISORIES

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