textproduct: Marquette

KEY MESSAGES

- Scattered showers continue marching east, departing the UP this afternoon.

- Hazardous swim conditions are expected for the beaches along Lake Superior east of Marquette today due to high wave action and strong rip currents.

- Showers and thunderstorms will be possible (up to 50%) Monday night into Tuesday.

- Temperatures will be close to seasonal averages most days through next week, with highs in the 70s and lows around and in the 50s.

DISCUSSION

Issued at 313 AM EDT Sun Aug 16 2026

Early morning KMQT radar returns show scattered rain showers over mainly the central UP around 06Z, though no lightning has yet been observed. Per RAP analysis, this is ahead of a 1011mb surface trough over mainly the west half of northern Ontario supported by an upper trough over the Ontario/Manitoba line. Elsewhere at 500mb, a closed high is centered over the ArkLaTex region with multiple shortwaves rotating around the top of the high. Troughs are also present over British Columbia and off the New England coast. Throughout the remainder of the weekend, the southern high and Pacific trough will make no meaningful progress, but the troughs off the East Coast and over central Canada will progress, leaving the UP in a stable, northwesterly flow pattern which will keep dry weather in the forecast from this afternoon (following the departure of showers to the east) to Monday evening. High temperatures remain seasonable and comfortable through Monday with highs only exceeding 80 degrees in the south-central. Tonight into Monday morning, lows fall to around the 50 degree mark for the interior and around the 60 degree mark at the Great Lakes shores.

Today through Monday afternoon, a 500mb trough will deepen and become a closed low as it swings along the Hudson Bay shoreline from Nunavut to Manitoba. Falling 500mb heights ahead of this closed low will lead to the formation of a surface trough that will once again bring rain shower chances to the UP around 00Z Tuesday. CAMs show some convective activity in Minnesota and northwest Ontario ongoing at 00Z Tuesday, though if convection survives crossing the lake and reaching the UP, it will be moving into stable air (HREF mean MUCAPE struggles to exceed 100 J/kg), though it will be a shear-rich environment as HREF mean 0-3km SRH balloons to 100-200 and deep speed shear is present (including the presence of a 100+kt jet at 250mb). Model soundings show meager lapse rates but plentiful deep moisture (LREF mean PWAT grows to about 1.25 inches, around the 75th percentile of climatology). Thus, if any thunderstorms can get going, some heavy rain rates could be observed, but severe thunderstorms seem unlikely given the timing of the showers not lining up well with diurnal destabilization. Unfortunately for the areas of growing drought for the UP, this rainfall does not look to be widespread, as LREF probabilities of 0.1 inch of rain by 00Z Wednesday are 25-33% for the west half and 35-55% for the east half.

Another dry spell then kicks off early Wednesday morning through at least Thursday evening. Models diverge significantly for the late week period, though the passage of another deep trough from the northwest looks to be the next mechanism for bringing shower and thunderstorm chances to the UP late this week into next weekend. With the continued background northwesterly flow aloft pattern, temperatures generally remain seasonal with highs in the 70s and lows in the 50s.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 148 AM EDT Sun Aug 16 2026

Scattered SHRA over much of the UP is leading to deteriorating flight categories through this morning, including 50+% chances of LIFR conditions at CMX and 50-70% chances of IFR at SAW/IWD. Gradual improvement is expected throughout the day at all sites, with chances of VFR exceeding 75 percent by 19Z at IWD, 21Z at CMX, and 23Z at SAW, though clouds may SCT out an hour or two prior to ceilings lifting by that point. Expect winds to shift to the northwest after the SHRA pushes through, occasionally gusting 15-20 kt in the afternoon hours.

MARINE

Issued at 313 AM EDT Sun Aug 16 2026

Wind gusts around or less than 20 kt on Lake Superior this morning increase over the east half of the lake to around 25 kt out of the northwest in the wake of rain showers. As the disturbance exits the region, winds relax to sub-20 kt tonight through Monday night (with the notable exception of southwesterly wind gusts funneling between Isle Royale and Thunder Bay Monday afternoon to 20-25 kt). Another disturbance passing over the lake Monday night into Tuesday will have gusty westerlies for the east-central portion of the lake to 20- 25 kt for Tuesday afternoon. Winds falling below 20 kt again Tuesday night will remain thus until the next disturbance arrives late in the week.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement from noon EDT today through this evening for MIZ005-006.

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