textproduct: Marquette

KEY MESSAGES

- Dry weather today will be followed by potential (20-50% chance) for showers and storms Tuesday morning through Wednesday afternoon. Strong to severe storms are not expected.

- Temperatures are expected to be seasonably warm to slightly above average through Wednesday, before cooling to slightly below average through the weekend.

DISCUSSION

Issued at 227 PM EDT Mon Aug 10 2026

Early afternoon GOES WV imagery indicates a broad troughing pattern across central and eastern Canada and ridging centered over the Four Corners, while the Great Lakes region remains under largely zonal flow. Skies will be mostly clear this afternoon before partly cloudy conditions take over this evening, with potential for some patchy fog overnight through early Tuesday morning. Low temperatures tonight are expected to be in the upper 50s along the shoreline, dipping into the low 50s inland.

Broad, low-amplitude troughing will continue to exist over the Great Lakes into the Northeast on Tuesday and Wednesday along the southern periphery of the Hudson Bay low. Lower level flow is ill-defined, but a weak zonally-orented convergence boundary is forecast to evolve on Tuesday, roughly bisecting the UP and possibly reinforced by the Superior lake breeze. There is also some weak positive theta- e advection in the 925-850 mb layer advertised by the NAM. Models differ substantially on the degree of instability present, ranging from near zero on the HRRR to near 1500 J/kg on the NAM3km. These differences are tied to the degree of near-surface moisture, as midlevel lapse rates remain fairly modest. Ensemble mean approach, as per the 12Z HREF, suggests SBCAPE values remain below 1000 J/kg, which will keep the likelihood of any stronger storms low, despite ample deep layer shear of around 40 kt. CAMs differ in shower coverage as well, and overall have trended lower likely due to the weak forcing and questionable low-level moisture. This keeps coverage generally in the 20-40% range, highest in the afternoon/evening.

The pattern does not change much into Wednesday, and questions about precipitation coverage continue accordingly. This will hinge upon moisture availability both near the surface and at upper levels. PoPs range from near zero over the west to near 50% over the south- central where there is the best probability of better moisture pooling ahead of a weak boundary approaching from the west. Although isolated storms cannot be ruled out, severe weather is again not expected due to the lack of instability.

Temperatures will be seasonable through the week, but with a slight downward trend toward the end of the week into next weekend. A drier airmass will arrive for Thursday and Friday keeping those days dry as ridging builds upstream, putting the local area in an ideal location for subsidence.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 106 PM EDT Mon Aug 10 2026

VFR conditions are expected to dominate the TAF sites the rest of today through Tuesday morning as high pressure builds in over the sfc. Light lake breeze winds this afternoon become calm/nearly calm tonight. While there is a less than 25% chance for FG at SAW tonight, the better chances for FG are over the eastern U.P.

MARINE

Issued at 227 PM EDT Mon Aug 10 2026

Winds will be less than 20 kt throughout the week this week as high pressure dominates. Patchy fog is possible through at least tonight, especially over central and eastern Lake Superior. An isolated thunderstorm cannot be ruled out over the Bay of Green Bay and Lake Michigan waters Tuesday afternoon through Wednesday afternoon (20% chance at any given time).

MQT WATCHES/WARNINGS/ADVISORIES

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