textproduct: Marquette

KEY MESSAGES

- Scattered showers and thunderstorms this afternoon and evening. Severe weather is not expected, but heavy rainfall and minor flooding is possible. Rain showers linger on and off through Saturday, mainly over the eastern two thirds of Upper Michigan.

- Temperatures fall back into the 70s to low 80s for the weekend, coolest near Lake Superior. Lower dewpoints will result in a more comfortable airmass on Sunday and Monday.

DISCUSSION

Issued at 350 AM EDT Fri Jul 31 2026

Early morning RAP analysis indicates the mid level ridge over the Plains has been flattened by the trough making its way over the Dakotas, highlighted nicely in GOES WV imagery. Back in the CWA, upper level diffluence, a subtle shortwave, and low level WAA are supporting showers and weak thunderstorms noted on the radar mosaic over north-central Lake Superior and Keweenaw County. The 7/31 0Z ARW seems to be capturing this the best, which would suggest these continue to progress southeast while mostly residing over the waters as they follow the CAPE gradient and low level wind flow. That said, there is a 20-40% chance for showers and weak storms in the counties near Lake Superior early this morning. Otherwise temps stay around 10F above normal in the 60s through sunrise.

The rest of today and tonight focuses on the Dakota trough which deepens as it moves over MN, IA, and WI. At the same time, a cold front presses in from the northwest. Although much of the energy with this system remains south of the area, continued low level moisture and diurnal heating will develop scattered thunderstorms this afternoon. Temps in the 70s to mid 80s above Tds in the mid 60s to low 70s (warmest T/Td in the east) support modest instability (1000-2000 J/kg). HREF mean PWATs between 1.6 to 1.8 overhead during the day (a few deterministic solutions such as the RAP go as high as 2.0 inches over the east) in the afternoon are above the NAEFS 90th climatological percentile. Given that storm motion vectors are slow and warm cloud depths are at least around 10 kft, rainfall amounts will be something to watch. The low shear environment indicates that well organized strong to severe storms are not expected. That said, minor flooding in poor drainage areas is a concern, especially if storms train over an area. HREF neighborhood probabilities of at least 1 inch of rainfall are at 30% across most of the UP save for the Keweenaw. There is up to a 50% chance of at least 1 inch of rain over the central/eastern UP where convergence along a Lake Superior lake breeze meets up with the more favorable environment. Mean QPF storm totals for the day range from 0.25 to 0.5 inches, but localized higher amounts up to 1 to 2 inches are possible in the central and eastern UP. WPC does capture this risk with the entire UP highlighted in a marginal risk of exceeding flash flood guidance (at least 5% chance).

Expect light rain to persist through Saturday morning as the cold front continues to sag south. Dry weather should then settle in through the early part of next week as high pressure and upper level ridging build in across the region. A low pressure system approaching from the west will bring a return to the active pattern in the middle part of next week with a chance (30-50%) of showers and thunderstorms. The forcing and instability look rather week during this period; therefore, high impact weather is not anticipated.

Temperatures warm back into the 80s for Monday and Tuesday with humidity increasing on Tuesday ahead of an approaching cold front. Showers and thunderstorms may accompany the front on Tuesday but the risk for organized convection remains uncertain at this point in time, with global models showing lower instability and shear.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 755 AM EDT Fri Jul 31 2026

The 12Z TAF period brings another round of scattered SHRA and -TSRA to IWD and SAW. CMX will be on the northern fringe of precip, lowering confidence in the afternoon forecast which currently reflects VFR persisting and only VCSH with a PROB30 group for -SHRA. IWD and SAW start off in VFR, but chances for lower vis increase with the progression of the day as showers increase from the southwest and TSRA begins this afternoon. While the TAFs reflect TEMPO or PROB30 groups for SHRA/TSRA with MVFR vis late this afternoon/evening, brief periods lower vis can't be ruled out. -SHRA linger at SAW into tonight, but BR/FG is possible into early Saturday morning lowering vis down to IFR/LIFR. Variable winds at SAW/IWD given lake breeze influences and precip.

MARINE

Issued at 350 AM EDT Fri Jul 31 2026

The lake remains under a weak pressure gradient through Monday resulting in mainly light winds, 20 kts or less. Thunderstorms over the central portion of the lake this morning continue progressing eastward, remaining sub-severe. Additional storms are possible again this afternoon, mainly over the south half of the lake. Otherwise expect quiet weather through Monday, with the chance for thunderstorms returning on Tuesday.

MQT WATCHES/WARNINGS/ADVISORIES

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