textproduct: Marquette

KEY MESSAGES

- Widespread fog is expected over the central and eastern U.P. tonight. The fog will be dense at times.

- Mostly dry weather through Saturday, then low chances (10-40%) for light rain return Saturday night.

- A period of cooler weather is expected for at least early next week as colder air pushes south across the region.

DISCUSSION

Issued at 226 PM EDT Thu Oct 22 2026

This afternoon GOES water vapor imagery and GFS model height analysis showed upper level ridging over the central U.S. ahead of an upper low that was now over the central California. Surface analysis and observations showed high pressure from the U.P. northeast into Ontario and Quebec. Under the high a weak pressure gradient was continuing to provide light winds to the area. With the weak flow, extensive fog that had developed overnight over the central and eastern U.P. along with the Keweenaw was taking its time dissipating. Most of the fog had lifted into a low stratus deck and was now draped from the Menominee and Delta Counties northwest towards Marquette and further on to the northern half of Keweenaw. The western U.P. avoided much of the fog and thus temperatures had warmed mid to upper 60s, while areas under the low clouds remained in the 40s.

Overall it will remain warm through the weekend, with the warmest days on Friday and Saturday when highs will be 15-25F above average for late October, ranging from the 60s far east to the mid 70s west, with even a few locations pushing the upper 70s. Record highs from locations with longer historical records are generally in the upper 70s to low 80s, thus high temperatures could come within 2-5F of the records.

The surface high pressure will push east tonight as low pressure deepens in the lee of the Rockies, helping to bring southerly flow, though still light, into the U.P. This will help pull moisture back north through the area tonight, enhanced by moisture from Lake Michigan. With relatively ideal conditions for radiational cooling expect fog to redevelop over the central and eastern U.P. Fog will become dense at times especially over the central third of the CWA. Headlines may be needed for dense fog tonight into Friday morning. Commuters should leave themselves extra time to reach their destinations. The developing southerly flow will help minimize cooling over the far west, while the central and east see limited cooling once the fog forms. Low temperatures will be a bit warmer tonight than previous nights.

Fog will lift on Friday morning with a warm day in store for the U.P. as the upper level ridge moves overhead and 850mb temperatures warm into the 10-13C range. Expect high temperatures in the 60s east to the mid 70s west, and even upper 70s over Ontonagon County and southern Houghton County. Dry weather will persist with south winds gusting to around 15 mph.

Saturday will be continued warm but also become windy. Low pressure tracking through northern Saskatchewan and into northern Ontario will bring a tightening pressure gradient and south winds will become gusty, 20-25mph and up to 35mph along the Lake Superior shoreline east of Keweenaw Bay. The gusty winds and warm temperatures (highs in the 60s and 70s) will bring a heighten concerned for fire weather, however, higher dewpoints in the upper 40s will keep RH over 40% except for parts of Ontonagon and Houghton counties were the RH could drop to 35%.

A cold front will sweep across the U.P. from west to east on Saturday night bringing a chance for rain showers. Deterministic models are trending drier and the chance for 0.1" or more of rainfall from the ensembles is only around 10%. Don't expect much in the way of rainfall if you do happen to get under one of the showers. Winds turn west behind the front and cooler, drier air will begin to work into the area through Sunday afternoon. Highs will be cooler but still above average, reaching the 50s west and 60s east. Humidity will fall as low as 30% over the interior west but winds look to remain under 15 mph at this time, limiting fire weather concerns.

High pressure passes east over Ontario and the Great lakes Monday and Tuesday favoring dry weather until late Tuesday/Wednesday when higher PoPs return. That said, with colder 850mb temps moving overhead early next week, delta-Ts maybe sufficient for isolated rain showers. Troughing from the west and a resulting sfc low pressure mid next week present better (although still low) chances for precip, but ensemble guidance quickly diverges on track and timing leaving low forecast confidence. The forecast reflects mostly slight chance PoPs (14-24%). Otherwise, temps return near normal in the wake of the cold front on Sunday peaking in the mid 40s to low 50s on Monday. Temps Monday night settle into the 20s to mid 30s, coldest interior west. A slow warming trend then persists the rest of next week.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 141 AM EDT Fri Oct 23 2026

Areas of stratus and dense fog are noted on regional webcams and satellite imagery tonight with LIFR fog at CMX. Thinking IWD stays fog free as weak southerly downsloping occurs and not much additional cooling takes place with an already 10 degree Td depression. Elsewhere at SAW, lowest confidence FG forecast is here as southerly and easterly areas of stratus/fg lift toward the central UP, though weak southerly upsloping may be able to help boost localized FG into the terminal by daybreak. CMX is likely to see FG persist through daybreak before scattering out. VFR cigs/vis return through the morning. Areas of dense fog may be present in the eastern UP through the rest of the day closer to Lake Michigan. Afternoon southerlies pick up between 10-15 kts with 15-20 kt gusts most likely at SAW.

MARINE

Issued at 226 PM EDT Thu Oct 22 2026

The main concern through Friday will be the redevelopment of dense fog over Lake Michigan and Lake Superior. Fog had mainly lifted to a low stratus deck this afternoon but expecting ideal conditions for the reformation of dense fog late tonight. A Dense Fog Advisory remains in effect for the north-central part of Lake Superior through the night. Dense Fog Advisories may need to be expanded late tonight.

Winds remain below 20kt through Friday afternoon and then strengthen Friday night into Saturday ahead of an approaching front. South winds will gust to 30kt by Saturday morning over the east-central part of Lake Superior (along and east of the Keweenaw) with a few gusts to near gale Saturday afternoon. For Lake Michigan winds will gust to 25kt by Saturday afternoon. The cold front will pass across the lakes Saturday night shifting winds westerly, up to 25kt over Lake Superior and up to 20kt over Lake Michigan. Light winds are expected on Monday and Tuesday less than 20kt.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for MIZ001-003>007-010>014-084-085.

Lake Superior... Dense Fog Advisory until 11 AM EDT /10 AM CDT/ this morning for LSZ162-263-264.

Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for LSZ240-241.

Lake Michigan... Dense Fog Advisory until 11 AM EDT this morning for LMZ221-248- 250.