textproduct: Marquette

KEY MESSAGES

- Isolated showers linger through this evening, mainly over the eastern half of Upper Michigan.

- Temperatures remain in the mid 60s to upper 70s through Sunday, coolest near Lake Superior. Lower dewpoints will result in more comfortable conditions.

- The chance for showers and thunderstorms returns on Tuesday as a cold front approaches the area.

DISCUSSION

Issued at 359 PM EDT Sat Aug 1 2026

Afternoon RAP analysis depicts a slow moving surface low over Illinois and Indiana, with high pressure beginning to build into Upper Michigan from northern Ontario. Northerly low level flow between these features has kept much of the Lake Superior shoreline shrouded in low stratus and fog through much of the day, although webcam imagery from around the area generally shows fog dissipating and visibility improving as of mid afternoon. Starting to see a few showers pop up on radar along the northern shores of lake Michigan and the WI border near a remnant frontal boundary analyzed through the Mackinac Straits and the southcentral UP. Could continue to see a few rumbles of thunder with this activity into the evening hours given modest instability on the order of 1000+ J/kg MUCAPE per latest SPC mesoanalysis, but would not expect much storm organization given meager wind shear. Any lingering shower activity will wind down tonight, giving way to drier northerly flow as the low and associated upper level trough continue to depart to the east. This will yield clearing skies and likely less fog coverage tonight as drier air works into the low levels of the atmosphere, but still could see some patchy fog in a few spots that have seen recent rainfall.

Expect pleasant sunny conditions on Sunday in dry northerly flow, with highs again holding in the 70s with cooler temps near Lake Superior. Clear skies and low dewpoints will make for a chilly Sunday night as temps dip as low as the low 40s in some interior locations, but do not expect temps to get quite low enough to warrant any frost/freeze consideration. Dry weather persists into Monday under high pressure, with temperatures warming back into the upper 70s to lower 80s as 850 mb temps warm to 15-17 C. The next chance of precipitation then comes on Tuesday as a trough approaches from the northwest and drives another cold front through the UP. This could also bring another round of thunderstorms to the area, but severe potential is TBD given uncertainty over timing and degree of instability and shear. Temperatures look to drop down into the 70s again on Wednesday behind the front, but will quickly recover back into the 80s on Thursday as additional systems bring more chances for precipitation towards the end of the week.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 720 PM EDT Sat Aug 1 2026

VFR conditions at IWD will be ongoing through the period as chances for overnight FG development are around 20% or less with winds primarily out of the north to northeast at 10 kt or less. Chances of overnight FG at CMX are a little better at around 35% (best chances in the 06Z-09Z window), but will leave FG mention out of this TAF issuance for now. SAW has been mired in a marine layer most of today that has resulted in consistent LIFR conditions since around 12Z this morning (with only a short break from 1730Z-1915Z). Satellite imagery shows that the marine layer is eroding with some dry air causing skies to the northwest of the terminal to scatter out, and eventually bring SAW to VFR, though the likelihood of that occurring prior to 05Z is only around 50%. Chances of FG redeveloping overnight is around 40-50%, so will keep some MVFR vis in the SAW TAF overnight despite the improving ceilings, though VFR conditions should prevail by 13 or 14Z.

MARINE

Issued at 359 PM EDT Sat Aug 1 2026

The lake remains under a weak pressure gradient through the forecast period, resulting in mainly light winds at or below 20 kts. Areas of dense fog have been stubborn to erode over the eastern half of Lake Superior this afternoon. Have extended the existing headlines through this evening, but should start to see some improvement tonight under drier northerly flow. Showers and thunderstorm are expected on Tuesday but there remains uncertainty as to the coverage and strength of the storms.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Dense Fog Advisory until 8 PM EDT this evening for LSZ247>251- 265>267.

Lake Michigan... None.