textproduct: Marquette

KEY MESSAGES

- Temperatures will remain very warm today and Friday but will remain below heat advisory criteria. Be sure to stay hydrated and have a way to cool off.

- There is a marginal risk (<15% chance) for strong to severe thunderstorms again today, some of which could produce hail and gusty winds.

- Additional thunderstorms are possible Friday and through the holiday weekend, with another chance for some stronger storms Friday.

DISCUSSION

Issued at 215 PM EDT Thu Jul 2 2026

Afternoon RAP analysis shows mainly WSW midlevel flow over the Great Lakes, in between ridging centered over the Southeast and low pressure near Hudson Bay. Another shortwave is rippling towards the area, currently over northeastern IA; this may eventually scrape the central and eastern UP with some showers and storms later this evening as it moves into WI. In the meantime, mid- and upper-level cloud cover is spreading into the area out ahead of it. Where skies remain clear so far (over the far western and eastern UP), some cumulus is popping on satellite, betraying destabilization. Particularly over the far east, where some lake breeze convergence may lend some forcing, I would not be surprised to see cumulus turn more agitated and some showers and storms kick off. Given SBCAPE already in excess of 2000j/kg and modest bulk shear of around 30- 40kts, storms today, whether diurnally-driven or moving in closer to 00Z with the aforementioned shortwave, could be on the stronger side. Gusty winds are the primary threat, but I would not be shocked by some small hail. Any storms that do reach the area as the shortwave heads towards the area should move out after 06Z.

Otherwise, temperatures are rising into the lower 80s across much of the UP, while remaining suppressed in the 70s onshore of Superior in the western UP and Lake Michigan in the east. Where we aren't getting this onshore flow, temperatures should peak in the mid/upper 80s for and possibly near 90 towards the WI border, though increasing cloud cover could throw a wrench in there. Temperatures remain elevated tonight, only falling back as far as the lower/mid 60s.

Friday will be a near carbon-copy to today, with additional chances for showers and storms given weak shortwave action and diurnal instability. With the nebulous forcing and marginal shear, and SBCAPE potentially exceeding 1000j/kg, the Marginal risk over the southern half of the UP looks justified, with gusty winds the primary threat. Expect another hot day as temperatures rise into the lower to mid 80s for most, and in the 70s along the lakeshores. The rest of the holiday weekend, temperatures moderate some as an approaching low pressure system causes flow to shift out of the northeast, but highs still range in the 70s to lower 80s and lows in the 50s. This system does also bring a potential for another batch of showers and storms later Saturday into Sunday, but with some of the deterministic and ensemble guidance favoring a storm track more to our south, thus far our best chances are closer to the WI border. Still, we aren't looking a washout with QPF topping out around a quarter of an inch for most; that said, where storms do occur, heavier amounts would be possible. Temperatures trend warmer again into next week as ridging recovers, and though drier weather is favored, diurnal instability presents almost daily chances for some convection.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 154 PM EDT Thu Jul 2 2026

VFR conditions prevail across Upper Michigan today as visible satellite shows just some high cirrus streaming over the area ahead of upstream convection over the Upper Mississippi River Valley. Expect these showers and storms to generally remain south of the terminals as they move through northern WI and possibly clip the southcentral UP tonight into Thursday morning. Therefore expect VFR conditions to persist through the period at all sites, with shower and thunderstorm potential remaining low enough (~20%) as to not warrant inclusion in the TAFs at this time. Winds will generally be out of the west-southwest around 10 kt at KIWD and KSAW through this evening, staying a bit stronger along the Keweenaw with some gusts to 20-25 kt at KCMX through around 22z. KSAW may experience a northerly wind shift later in the afternoon if the lake breeze makes it to the terminal, but do not have high confidence in this outcome. Winds will diminish below 10 kt at all sites after 00z this evening.

MARINE

Issued at 215 PM EDT Thu Jul 2 2026

Afternoon satellite reveals at least some lingering patchy fog over the lake today, particulary between the Keweenaw and Isle Royale and closer to the international boundary. Webcams indicate that this is dense at times. With a humid airmass in place, patchy fog remains possible through tonight. Otherwise, additional weak waves may bring more storms out over the lake through the holiday weekend, though confidence is low. Weak gradient flow will result in light winds, below 15kts through the weekend, with the exception of stronger winds in the vicinity of thunderstorms.

MQT WATCHES/WARNINGS/ADVISORIES

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