textproduct: Marquette

KEY MESSAGES

- Spotty showers and thunderstorms are re-developing across the eastern and south-central UP.

- A warming trend kicks off late weekend, bringing unseasonably warm temperatures and humid conditions into next week. This is leading to a potential for heat-related impacts to vulnerable populations.

DISCUSSION

Issued at 205 PM EDT Thu Jun 25 2026

Early this afternoon, low pressure is tracking through northern Lower Michigan while ridging builds into the UP from the Northern Plains. Water vapor shows dryer midlevel air spilling into the area, with plenty of clearing onshore and even well inland of Superior over the north-central and western UP. However, agitated cumulus and some spotty showers developing over the south-central and interior- western UP betray unstable conditions developing away from Superior, and indeed RAP shows around 1000j/kg of SBCAPE there with up to 500j/kg elsewhere in the UP. To the east, nearer to our exiting system and with the aid of some lake breeze interactions, spotty shower activity also continues. Model soundings over the eastern and south-central UP continue to show tall, skinny CAPE through the rest of the afternoon, though shear is lacking. Thus, some non-severe storms remain possible, which may result in a quick, heavier downpour. Gusty winds would be possible due to core collapse in our shear-starved environment, and some small hail is not out of the question (note a -20C level of just ~20kft at this morning's sounding out of MPX).

Outside of today, the rest of this week looks to remain dry as high pressure ridging builds in from Canada and stays settled until around Sunday. In addition, expect the below normal temperatures through Friday (highs in the 60s to lower 70s/lows in the 40s) to give way to above normal temperatures by early next week as a pattern shift occurs. As a low barrels into the PacNW late this week before lifting into the central CONUS and Canadian Prairies late this weekend, expect this low to push the cooler Canadian air out of our neck-of-the-woods and instead set us up with Gulf air via SW/SSW flow. With the vertically-stacked low eventually just spinning over the Canadian Prairies for the first half of next week, expect shortwave lows to rotate up from Colorado and the Southern Plains into the Upper Midwest, bringing showers and thunderstorms back across our area from time to time. With ensembles showing temperatures aloft approaching the max of modeled climatology by early next week, there is a non-zero chance that a Heat Advisory or more could be needed for portions of Upper Michigan, particularly in the west where the NBM is already hinting at high temperatures approaching 100 on Monday. We could see similar temperatures on Tuesday into the middle of next week as well, provided that enough sunshine reaches the sfc those days. With the Gulf air on tap, expect muggy conditions across the area next week, making the outdoors and any spot that isn't air conditioned acutely uncomfortable. Therefore, take plenty of water breaks and avoid strenuous labor during the hottest part of the day next week, as heat exhaustion and heat stroke could become genuine threats.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 139 PM EDT Thu Jun 25 2026

VFR conditions will continue at SAW and CMX into this evening with light winds and clear skies. MVFR cigs at IWD should become VFR as the afternoon progresses and drier air works its way into the area. Overnight fog will likely develop under clear skies and light winds. There is some uncertainty as to how dense the fog will be. Will keep vis IFR at this time but dense fog can not be ruled out (20% chance for vsby less than 1/4 mile). Any fog should mix out during the morning hours on Friday with VFR conditions the rest of the period.

MARINE

Issued at 205 PM EDT Thu Jun 25 2026

Light winds of 20 knots or less persist into the weekend as weak high pressure ridging builds in from Canada. However, starting on Sunday, a low lifts from the Rockies into the Canadian Prairies and central CONUS, eventually just spinning over the Canadian Prairies for the first half of next week. As this occurs, the Upper Great Lakes becomes set up under Gulf air as shortwaves rotate into the region from the SW. Thus by Sunday, expect to see winds increase from the E to 20 to 30 knots as thunderstorm chances move into the lake late in the day into the overnight hours. While the winds do look to veer towards the S Sunday night into Monday, expect them to remain at 20 to 25 knots across the lake (highest over the east half), with additional showers and thunderstorms potentially moving over Lake Superior once again late Monday.

MQT WATCHES/WARNINGS/ADVISORIES

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