textproduct: Marquette

KEY MESSAGES

- Dry weather continues through tonight, then low chances (20-40%) for showers and thunderstorms return on Tuesday with a cold front. Strong to severe storms are not expected and accumulations will be limited.

- Temperatures rebound into the 80s for much of the area today.

DISCUSSION

Issued at 326 AM EDT Mon Aug 3 2026

Early morning GOES WV imagery shows the mid level ridge extending into the Upper Mississippi River Valley, pressing the downstream trough over the Lower Great Lakes and along the province line of Ontario and Quebec eastward. Surface high pressure ridging extending from James Bay across much of the Mississippi River Valley is supporting the calm conditions within the CWA. SPC mesoanalysis indicates the entire CWA is under less than 1 inch of PWATs with values as low as 0.5 inches over the east half. This and clear skies have allowed radiative cooling processes to lower temps into the 50s to mid 40s so far. Forecasted lows in the 40s to mid 50s, coldest interior remain on track.

Dry weather continues through tonight as the ridge builds into the Great Lakes and sfc high pressure becomes confined to the Lower Great Lakes/OH River Valley. Meanwhile a shortwave trough over the northern Rockies tracks to Manitoba and western Ontario by Tuesday morning, increasing sfc troughing from the west which bears a cold front. The increasing southwest flow warms 850 mb temps to 18-22 C by late tonight, and with 500 mb height rises yields a warm up with widespread highs in the upper 70s to upper 80s. Lows stay mild tonight in the upper 50s to upper 60s.

The shortwave trough swings through northwestern Ontario on Tuesday, driving a cold front and weak surface trough across the UP. Better dynamic forcing remains to the north of the UP and instability is capped much of the day, generally peaking around 1000 J/kg. Despite PWATs to between 1.5 to 1.8 inches with this boundary, model soundings are lack luster for deep moisture and the quick nature leaves much to desire for rainfall amounts. Even with sufficient deep-layer shear, strong to severe storms seem unlikely. As a result, the forecast reflects 20-40% PoPs from west to east on Tuesday. NBM probabilities of at least 0.25 inches are only between 10-40% over the east half of the UP and 0Z HREF probabilities struggle to even reach 10-15% just about anywhere within the CWA.

Temperatures fall back into the 70s on Wednesday behind the front, but look to quickly rebound back into the 80s on Thursday as additional systems bring more chances for precipitation from Friday into the weekend.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 726 AM EDT Mon Aug 3 2026

VFR conditions prevail through the duration of the 12Z TAF period as weak high pressure overhead this morning shifts to the southeast and a cold front approaches from the west. Expect light southerly winds today around 5 to 10 kts to increase to 10 to 15 kts late tonight/early Tuesday morning out of the southwest with gusts into the low 20 kt range. Wind directions at CMX this afternoon could briefly become variable due to competing lake breezes, leaving low confidence in exact direction timing until easterly winds prevail late afternoon. Winds at CMX then follow similarly to IWD/SAW tonight out of the south to then southwest. Otherwise LLWS impacts CMX and IWD toward the end of the TAF period.

MARINE

Issued at 326 AM EDT Mon Aug 3 2026

High pressure keeps winds below 20 kts today as dry weather persists over the region. Showers and thunderstorms are anticipated with the arrival of a cold front on Tuesday, but there remains uncertainty as to the coverage as they continue eastward. Strong to severe storms are unlikely. Southerly winds increase to 15-20 kts ahead of this front tonight with gusts around 25 kts. Small Craft Advisories may be needed Tuesday on both Great Lakes nearshores as winds become southwest to west in the wake of the front.

Winds drop back below 20 kts Tuesday night behind the front, likely staying below 20 kts the remainder of the week (70% chance). Could see additional chances for showers and thunderstorms towards the end of the week.

MQT WATCHES/WARNINGS/ADVISORIES

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