textproduct: Marquette

KEY MESSAGES

- Temperatures will be close to seasonal averages most days through the week, with highs in the 70s and lows in the 40s and 50s.

- Showers and thunderstorms are possible (40-70% chance) late Thursday into Friday as a weak system moves through the area.

DISCUSSION

Issued at 357 AM EDT Wed Aug 19 2026

The general pattern through the forecast period and toward the end of August places the UP under northwest flow aloft. This yields seasonal to slightly cooler than normal temps, captured by the CPC 6- 10 day temp outlook. The mid level closed low over northern Ontario and Hudson Bay gradually makes its way to northern Quebec for Thursday into the weekend, but likely will be replaced by another deep trough early next week. Model discrepancies exist regarding the timing and placement of this trough (or if another closed low develops), but this currently does not yield significant changes to the northwest flow anticipated for over the Upper Great Lakes.

Clear skies and light winds early this morning are allowing temperatures to fall well below normal. Currently, western interior portions of the UP are already in the low to mid 40s per ground- based obs, and a few upper 30s cannot be ruled out by daybreak. Elsewhere, central and eastern portions of the UP are generally in the upper 40s to low 50s with the Keweenaw in the mid to upper 50s. Continued to trend toward a cooler bias with 10th percentile NBM for overnight lows again tonight after highs in the 70s today. Once again, tonight's lows will dip into the 40s to mid 50s, coldest across the interior west where temps could drop into the mid to upper 30s.

High pressure over the Great Lakes Thursday morning shifts southeast, giving way to a shortwave and weak sfc trough the west. WAA reintroduces rain chances into Thursday night and a trailing shortwave continues PoPs on Friday. Strong to severe storms are not expected given that probabilities of 1000 or greater CAPE values struggle to reach 30% until Friday when bulk shear falls off. As far as rainfall amounts go, 24 HR NBM probabilities for 0.25 inches or more are in the 30-60% range with 15-25% chances for at least 0.75 inches. While any storms that do form could put down locally heavy rainfall, a widespread heavy rainfall is not expected. Thus not expecting appreciable improvements to the ongoing drought conditions over the south and west. A cold front on Saturday yields one more day of showers and non severe storm chances (15-30%) before high pressure returns with mostly dry weather into early next week.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 103 AM EDT Wed Aug 19 2026

VFR conditions continue today as high pressure ridging pushes through the region. Expect the winds to become lake breeze dominated by the afternoon hours.

MARINE

Issued at 321 PM EDT Tue Aug 18 2026

Lake Superior - Southwest winds of 15-25 kts are expected over the west, particularly between Isle Royale and the northwest shores where winds are funneled. Winds shift northwest tonight as they fall below 20 kts lakewide. High pressure building in through Thursday morning keeps winds below 20 kts through Friday. A cold front on Saturday increases northwest winds to 15-20 kts lakewide, particularly over the east where gusts approach the 25-30 kt range. Northerly winds remain elevated until Sunday night when high pressure brings back calmer conditions. A few thunderstorms are possible in the west Thursday evening, but strong to severe storms are not expected.

Northern Bay of Green Bay and northern Lake Michigan - Overall expect winds less than 20 kts through Thursday night. Scattered showers and storms are expected into this evening as a cold front pushes through the area. These could bring marginally severe wind gusts up to 35 kts and small hail. A system Thursday night and Friday brings back shower and storm chances, but strong to severe weather is not expected. Southwest wind gusts up to 25 kts are expected ahead of this system on Friday, particularly near Manistique. Winds diminish Friday night, then become northwest for Saturday, once again increasing gusts up to 20-25 kts for the weekend.

MQT WATCHES/WARNINGS/ADVISORIES

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