textproduct: Marquette

KEY MESSAGES

- A couple of isolated showers and thunderstorms are possible in the interior central/west U.P. this afternoon.

- A warming trend continues through this 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 237 PM EDT Fri Jun 26 2026

Surface high pressure sprawled out over the area is ensuring quiet weather so far, though water vapor imagery reveals a weak shortwave rippling into the Great Lakes that has brought an increase in high cloud cover. Additionally, surface observations and radar show lake breeze development off of both Superior and Lake Michigan, with cumulus is beginning to pop over the central UP along the boundaries. Lower level lapse rates are on the steep side, and RAP analysis indicates weak instability (around 500j/kg of CAPE); so, will not totally rule out a few showers. As to that weak shortwave, nothing more than passing cloud cover is expected with our otherwise moisture-starved environment. Temperatures are peaking in the 70s away from the lakes, and are falling back into the 60s behind the lake breeze. Tonight, some patchy fog will be possible again as winds remain calm and skies stay partly cloudy. Temperatures tonight should come in slightly warmer than last night, bottoming out in the mid 40s inland and lower 50s lakeside with our warming airmass.

The warming trend continues into the weekend and onwards courtesy of a pattern shift that features a PacNW low moving through the Rockies, lifting into the Canadian Prairies early next week. This will set us up with Gulf air, bringing anomalously warm temperatures and humid conditions overhead. Thus, with the NBM highlighting high temperatures approaching 100 in some spots in the west and central Monday and especially Tuesday (when 850mb temperatures may exceed 20C), some heat related products (like a Heat Advisory) may need to be issued in the future given the stress the hot and humid weather may cause. In addition, with shortwaves expected to roll into the region from Colorado and the Southern Plains next week, we could see several rounds of showers and thunderstorms across the area. The first of these looks to move through late Sunday into Monday. With the European EFI highlighting CAPE and, albeit to a lesser extent, shear close to the max of modeled climatology, and with some areas of the U.P. approaching a Shift-to-Tails close to 1, there is a non- zero chance for some severe weather early next week. However, given that this is not our typical flow regime for severe weather, there are significant doubts on if this will actually materialize or if this will be yet another 'bust' prediction again for this summer (severe weather threats are over-estimated from more southwesterly flow regimes so far this summer). Temperatures may taper a few degrees as we head towards the later half of next week. That being said, expect the very warm conditions to continue to the end of the forecast period and beyond as southerly flow from the Gulf continues.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 706 PM EDT Fri Jun 26 2026

VFR conditions will prevail through the TAF period. Passing high level (FL200+) cloudiness can be expected into tonight. Winds will remain <10kt through the TAF period. Once again, fog chances are low (20-30%) at CMX and SAW, but cannot be entirely ruled out. Should patchy FG form, it could be dense (50/50 chance that if fog forms, vis would be sub-1SM).

MARINE

Issued at 237 PM EDT Fri Jun 26 2026

Generally calm conditions (i.e. no significant weather and winds of 20 knots or less) continue over Lake Superior today into Sunday morning as high pressure ridging remains settled overhead. However, as a PacNW low lifts from the Rockies this weekend into the Canadian Prairies early next week, expect the change in flow to allow shortwaves to begin moving over the Upper Midwest and Upper Great Lakes as early as Sunday. Therefore, expect to see winds increase from generally the east on Sunday, gusting up to 20 to 30 knots by the afternoon hours. In addition, expect the return of showers and thunderstorms, with a non-zero chance of severe weather possible early next week (there are serious doubts on whether this severe weather threat will materialize, but as for now the threat is at a non-zero chance given the hot and humid airmass moving overhead). Generally gusty east to south winds of 20 to 30 knots continue over the lake early next week until a shortwave low moving through on Tuesday potentially calms the winds down to 20 knots or less again behind it.

MQT WATCHES/WARNINGS/ADVISORIES

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