textproduct: Marquette

KEY MESSAGES

- Dry weather persists today with above normal temperatures. - Elevated fire weather conditions today across much of Upper Michigan due to relative humidity values around 20%, warm temperatures, and wind gusts of 15-20 mph.

- Scattered showers and thunderstorms return on Thursday, with another round likely Friday afternoon and evening. Uncertainty remains regarding precise timing and rainfall amounts in storms. Additional chances for convection linger into the weekend.

DISCUSSION

Issued at 410 AM EDT Wed Jun 3 2026

Morning water vapor imagery and RAP analysis indicate the persistent omega block is finally starting to show signs of breaking down as one upper low lifts from Montana into southern Saskatchewan while the other pushes into the Atlantic from the Canadian maritime provinces. Nonetheless, high pressure continues to dominate the Great Lakes for one more day as the axis of the positively tilted upper level ridge extends from Quebec down through the Lower MS River Valley. This will yield another warm and sunny day across Upper Michigan with just some patchy high cirrus traversing the region from the west. Low level southerly flow and 850 mb temps nudging up into the 13-14 C range will help to make today the warmest day of the week, with most locations in the 80s this afternoon, save for the areas adjacent to Lake Michigan. Dewpoints will mix out efficiently again today and bring another afternoon of minimum RH values in the low to mid 20s in most locations if not the upper teens away from the lakes. While elevated fire weather conditions will still be rather borderline, expect winds to be a bit gustier today as surface high pressure drops south of the area and gradients increase. Thus opted to issue a fire weather SPS for all areas except the Keweenaw given the likelihood for some gusts in the 15-20 mph range this afternoon. Continue to heed those burn bans this afternoon.

Guidance continues to indicate that tonight into Thursday will bring about the final collapse of the decaying ridge from the omega block as the Montana low propagates eastward, reaching Ontario sometime Thursday afternoon to early evening. At this point, however, deterministic and ensemble guidance suggest the low will dissipate as ridging builds in quickly behind it over the Canadian Prairie into Friday. At that point, flow over the Great Lakes will be more zonal, but sensitive to additional, poorly-timed shortwave action emanating out from the Northern Plains during the daytime hours Friday. A more vigorous shortwave digs into the Great Lakes Friday evening into early Saturday. What does this mean for our precip chances as we finish out the work week? Although the passage of the initial low Thursday coincides with a plume of anomalously high PWAT reaching the UP from the Gulf, guidance suggests minimal synoptic forcings at this time. From a buoyancy standpoint, however, the LREF up to 70% probability of 250 J/kg of MUCAPE over the western UP early Thursday morning, and 20-40% probability of 1000 J/kg of MUCAPE in the CWA Thursday evening. By Friday evening, several hundred j/kg of MUCAPE is analyzed over the region. That said, shear both days is limited, but this does point to a chance for thunderstorms, some marginally severe, both days. Thursday, LREF shows 30-40% chance of 6-hour precipitation greater than 0.1", with higher accumulations in the western UP. Friday, probabilities jump up to 30-60%. Higher totals in excess of a quarter-inch would be possible where thunderstorms develop. So for Thursday and Friday, chances exist of a wetting rainfall accumulations and a thunderstorm or two, but coverage remains in question, and the threat of severe weather is minimal.

Chances for convection linger into Saturday before ridging builds in again for Sunday and early the following week. After temperatures turn more seasonable Thursday through Saturday, they trend upwards again thereafter with some of the interior-UP taking a run at the 90 degree mark.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 730 AM EDT Wed Jun 3 2026

High pressure will maintain VFR conditions across Upper Michigan for the duration of the 12z TAF period. Expect light south to southwest winds between 5 and 10 kts at all sites this afternoon.

MARINE

Issued at 410 AM EDT Wed Jun 3 2026

High pressure over the Great Lakes will keep winds below 20 kt through this evening. The high shifts east tonight into Thursday with southerly wind gusts increasing to around 20 kt. This may bring about the next round of small craft headlines for the northern Lake Michigan zones by Thursday afternoon, with the Lake Superior nearshores looking to remain sub-advisory for now. There will be a slight chance of thunderstorms ahead of a weakening disturbance tonight into Thursday, and again Friday. Otherwise, expect winds to fall below 20kt for Friday onwards while ridging returns to the region into early next week.

MQT WATCHES/WARNINGS/ADVISORIES

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