textproduct: Marquette

KEY MESSAGES

- High temperatures remain above-normal for today.

- A cold front brings a batch of showers and thunderstorms to the area this afternoon and evening, with localized heavy rainfall. There is a Marginal Risk (category 1 of 5) for severe storms over the western half of the UP.

- Pleasant temperatures are in store this weekend through next week, with rain showers and storms returning from time to time.

DISCUSSION

Issued at 251 AM EDT Fri Aug 7 2026

Early morning GOES water vapor features midlevel troughing over central Canada and the Northern Plains, extending from a broad midlevel low spinning around Hudson Bay. An embedded shortwave is moving into far western Ontario, with an associated cold front draped southwestward across NW MN and into the Dakotas. Closer to home, we remain under a tightening pressure gradient that has allowed for breezy SSW winds over the western half of the UP. Skies are so far mostly clear, with temperatures only falling back into the lower/mid 60s so far. Expect temperatures to bottom out a couple degrees cooler, into the upper 50s and lower 60s for most. Nighttime microphysics is hinting at some patchy fog development over northeastern WI already, so will not rule this out over the eastern half of the UP, but increasing winds should keep this patchy and low- impact. Heading into the daytime hours, expect southerly wind gusts to pick up across the rest of the area, while temperatures rebound into the lower to mid 80s for most.

The frontal boundary finally makes its way through the UP later today. While 0-6 km bulk shear isn't all that impressive along the cold front (only around 30 kts), with models trending the cap weaker at around 850mb, convection could become sfc-based by the afternoon hours. Thus, we may see SBCAPE/MUCAPE at around 1200 to 1500 J/kg by the afternoon to early evening hours over the west half. In addition, with strong theta-e advection lined up well with cold frontogenesis in the lower to mid levels, thinking there will be robust mechanical lift along the front to produce strong updrafts to support linear convection Friday afternoon. This is generally supported by the varying CAMs; while there is still a range on the timing, the general model consensus is that showers and storms move in during the mid-afternoon hours (2-4 PM EDT). Thus, while generally not expected along the line, a strong thunderstorm or two could bring some marginally severe winds (i.e. up to 60 mph) to the sfc over the west half this afternoon into early evening; thus, the Marginal Risk (category 1 of 5) that SPC has over us. In addition to the potentially stronger winds via the convection, some heavy rainfall is expected given the robust lift along the front. With PWATs generally getting up to around 1.50 inches ahead of the cold front, some heavy rainfall in excess of 1 inch could be seen across some spots of Upper Michigan; as of the time of this writing, ensembles show up to a 50% chance that over an inch of rainfall between this afternoon and Saturday morning, with the highest chances over the west and north central. Looking at the LPMM for the REFS, the expected rainfall ranges from a quarter inch to 2+ inches over the west and north central, with the Porkies seeing 4+ inches. Therefore, while not expected, there could some spots, especially in the west, where some ponding of water/flash flood could occur. Across the rest of the U.P., expect generally a tenth of an inch up to potentially a whole inch of liquid by Saturday morning.

Moving into the rest of the forecast period, expect generally pleasant temperatures with highs in the 70s as a somewhat more zonal to northwesterly flow sets up across the Upper Great Lakes. While some weak sfc ridging generally sets up across the area, some weak shortwaves from time to time look to bring additional showers and thunderstorms to the area this weekend through next week. With 850mb temperatures dropping to around 9 to 10C behind the cold front early on Saturday, we may see some lake effect clouds over the northwest wind belts early Saturday morning, before warming temperatures bring an end to the cloud cover. Looking at just the 0-6 km bulk shear and MUCAPE, there is a chance that we could see some stronger storms come Sunday, but confidence on this is very low at this time (<5% chance). In addition, with a shortwave low on Monday having trended further south and now bringing the wrap-around moisture over the U.P., we could see at least a wetting rainfall across the area then (the NBM shows a 10 to 60% chance for at least a quarter inch of rainfall on Monday). By around next Thursday, we could see some lake effect clouds return as strong CAA with 850mb temperatures down to 6C potentially drop across Lake Superior.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 114 AM EDT Fri Aug 7 2026

VFR conditions prevail at all sites through the TAF period. The biggest impact to aviation during this period will be SHRA and TS from a cold front sweeping west to east through the TAF sites through the period. There is around a 15-20% chance of conditions falling to MVFR with these showers but confidence is too low to include with this TAF issuance. Expect southerly to southwesterly winds ahead of the front around 10 kt (+/- a few knots) that veer westerly to northwesterly behind the front in the evening to overnight hours.

MARINE

Issued at 251 AM EDT Fri Aug 7 2026

Winds pick up out of the south/SW this morning ahead of an approaching cold front, with gusts up to 20-30kts becoming more common. Winds look to die down again to 20 knots or less as the front passes through this afternoon. That being said, some strong and erratic winds greater than 34 knots could be seen with the convection along the cold front over at least the western half of the lake this afternoon and evening. Could see some westerly wind gusts of 20 to 25 knots across Lake Superior on Saturday before warm air advection causes winds to fall back down to 20 knots or less again Saturday night, with some showers and storms being possible late Saturday night into Sunday morning. Generally quieter weather is expected for the first half of next week over Lake Superior.

Over northern Green Bay and northwestern Lake MI, generally quieter weather is expected until southerly winds pick up to 20-25kts ahead of the cold front this afternoon. Some showers and storms are possible by the evening hours, then winds dying down to 15 knots or less after midnight. Light winds of 15 knots or less are expected over northern Green Bay and northwest Lake MI the rest of this weekend through early next week, although some showers and storms could once again move through the area early Sunday and again on Monday.

MQT WATCHES/WARNINGS/ADVISORIES

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