336 FXUS63 KMQT 110708 AFDMQTArea Forecast Discussion National Weather Service Marquette MI 308 AM EDT Thu Sep 11 2025
.KEY MESSAGES...
- Areas of dense fog are possible across the U.P. through this morning.
- Drier weather persists until Friday night.
- Warmer temperatures reach the 60s and 70s most days for the forecast period.
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.SHORT TERM /THROUGH FRIDAY/... Issued at 308 AM EDT Thu Sep 11 2025
Morning RAP analysis has a ridge axis broad ridging over the Plains and Prairie Provinces, supporting sprawling surface high pressure centered over Ontario. Water vapor imagery shows dry midlevel air over the Great Lakes, but with plenty of lower-level moisture in place courtesy of recent rainfall and northeast flow off of Superior, the UP remains socked in under low stratus. Fog is also evident in surface observations and available webcams, and it continues to be dense at times with some spots showing sporadic drops in visibility well below a mile. Given that this is not very widespread, and that these lower-end visibilities are more fleeting under widespread cloud cover, will hold off on any headlines. Otherwise, temperatures are staying rather mild, hovering in the mid 50s for most.
High pressure in place will allow for quiet conditions to wrap up the work week. Fog and low stratus slowly diminish this morning, with more breaks of sunshine during the afternoon as temperatures peak in the 60s to near 70. Soundings are supportive for at least some patchy fog development again tonight into early Friday morning while temperatures fall back into the 50s and possibly upper 40s. Expect increasing clouds Friday ahead of another shortwave that will eventually bring rain chances Friday night. Winds generally out of the south will help to usher in a warmer airmass, with highs ranging in the 70s.
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.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 308 AM EDT Thu Sep 11 2025
A weak clipper system moving over top of upstream ridge arrives Friday evening, with a quick round of rain Friday night into the early morning hours of Saturday. Some thunder is also possible with ensembles showing several hundred, possibly to near 1000j/kg of elevated CAPE as well as around 30kts of shear to sustain updrafts. Still, given the weak nature of forcing and marginal parameters, severe weather is not expected. Though widespread heavy rain is not expected, with most of the area looking at rainfall totals blow a quarter-inch, latest guidance is showing some heavier embedded totals as high as 0.25-0.50in. This is heaviest nearer the WI border in the western and south-central UP, where greater instability is more supporting of thunderstorm development. Showers/storms quickly move out Saturday morning. The clipper will have a negligible impact on temperatures as the upper level ridge quickly becomes re- established overhead, keeping highs in the 70s through the weekend and into the early part of next week.
Ensemble show good agreement in maintaining upper level ridging over the region through the first half of next week as the ridge axis slowly shifts eastward through northern Ontario. The position of the ridge axis will be critical, as a farther east solution would potentially allow embedded shortwave disturbances to brush the area and bring periods of showers or thunderstorms during the first half of the week. This is reflected by NBM PoPs which keep a 15-30% chance of precipitation across the area Tuesday into Wednesday.
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.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 107 AM EDT Thu Sep 11 2025
Flight restrictions to persist through this morning at all TAF sites due to lingering low level moisture. LIFR will be the predominant flight category with airport mins at times before daybreak. Gradual improvement will commence around mid-morning with slow improvement to MVFR. Fog and low stratus will break out to VFR during the late morning to early afternoon. Light winds and VFR skies are expected through the rest of the afternoon. Patchy dense fog is possible once again tonight.
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.MARINE... Issued at 308 AM EDT Thu Sep 11 2025
Light winds of generally 10-15 kt or less expected through the period as high pressure builds over the region. The exception will be on Sunday, when a tighter pressure gradient over the Upper Midwest may result in stronger 20+kt gusts over western Lake Superior. Meanwhile, satellite continues to show plenty of lower cloud cover over the lake and the Upper Peninsula, where surface observations show visibility dropping well below a mile at times. The Dense Fog Advisory thus remains in effect through Thursday afternoon as conditions will remain conducive to fog formation. Patchy fog may also expand to the eastern half of the lake and northern parts of Lake Michigan tonight into Thursday morning. A weak clipper will bring some light rain and potentially a few thunderstorms to the area Friday night into Saturday morning.
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.MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Dense Fog Advisory until 2 PM EDT /1 PM CDT/ this afternoon for LSZ162-240>244-263-264.
Lake Michigan... None.
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SHORT TERM...LC LONG TERM...CB/LC AVIATION...BW MARINE...CB/LC
NWS MQT Office Area Forecast Discussion