textproduct: Marquette

KEY MESSAGES

- Northwest lake effect snow wraps-up today.

- Southwest gales of 35 to 40 knots are expected over the western lake late tonight into Monday. Heavy freezing spray is also expected over the far western lake tonight.

- A burst of moderate to heavy snowfall could be seen over the Keweenaw and east half of the U.P. late tonight into Monday morning. Winter Weather Advisories over the east for this could be forthcoming.

- Temperatures start climbing early this week, with above freezing highs expected by Tuesday.

- Multiple gale events could be seen across Lake Superior this week.

- A strong Clipper low could bring high winds and a flash freeze setup across the area Thursday. Continue to monitor the forecast as impacts could change depending on the strength and track of the low.

DISCUSSION

Issued at 328 AM EST Sun Dec 14 2025

One last burst of northwest lake effect snowfall is being felt across the region today as the dying low responsible near the mouth of the St. Lawrence Seaway this morning allows ridging from the Northern Plains to move in over us. This ridging will push the lake effect away from the U.P. from west to east throughout the day today, with the last of the LES (lake effect snow) ending over the far east by early this evening. Nevertheless, still seeing some strong LES bands over the east via our radar as of the time of this writing, with dBZs between 20-30 within the lake effect bands. Thus, as we continue to warm and increase time in the DGZ aloft (increasing SLRs closer to 20:1, meaning the snowfall is becoming fluffier), we are seeing moderate to occasionally heavy snowfall occurring over the eastern U.P. early this morning (snowfall rates of 1/2 to 1 inch per hour at times). Thus, the east could see an additional 1 to 4 inches of fluffy snow before things start to dramatically ramp down late this morning into this afternoon. Areas of blowing snow are also still possible early this morning too, especially along M-28 west of Munising to the Marquette County line. However, as the winds drop today, expect the blowing snow concerns to go away by the mid-to-late morning hours as well thanks to the ridging building in.

While the ridging moving in by this afternoon looks to bring some sunnier skies across most of the U.P., don't expect the clouds to stay away all that long as a Clipper low drops into the area late tonight into Monday morning. While temperatures will be warmer tonight in comparison to early this morning, we can still expect the lows to be in the single positive digits, with the coldest temperatures mostly expected early tonight ahead of the Clipper's arrival. As the Clipper dives through Lake Superior late tonight, some modest Q-Divergence and strong warm frontogenesis could lead to a quick-hitting 1-4 inches of snowfall over the Keweenaw and eastern half of the U.P. by Monday morning. With snowfall rates getting to around 1 inch per hour in this frontogenetic band, I would have already issued a Winter Weather Advisory for Alger, Schoolcraft, and Luce counties if there wasn't the current one already going until late this morning. Therefore, I will let the dayshift be the ones to issue the Winter Weather Advisories, provided the going forecast does not change. CAMs highlight the system snowfall ending by the mid-morning hours over the east, although some light lake effect snow showers look to continue across the west to northwest wind snow belts until Monday night.

With the breakdown of the rex block that was over the Pacific Northwest now underway, expect temperatures to rise from well below normal to above normal between now and the middle of this week. By the time the Clipper passes by us Monday, expect temperatures to return to around normal across our area as lows Monday night range from the upper single digits to mid teens. As another Clipper moves through the Canadian Prairie and northern Ontario Monday night through Tuesday, expect some of the warmest air we've seen in weeks to bring highs back into the mid-30s to lower 40s across the area Tuesday. While some weak frontal forcing could create some drizzle/freezing drizzle/snow flurries in spots over the Keweenaw and east Tuesday, nothing is really expected impact-wise as precip amounts will only amount to a trace (if even that) as the better forcing associated with the Clipper will be located in Canada. That being said, we could see some melting across the area Tuesday as increasing southwesterly winds could bring the south-wind downslopes into the lower 40s by the Lake Superior shoreline. As the cold front of the low pushes through late Tuesday through Tuesday evening, we could have some strong winds mix to the sfc, potentially even up to 40 mph in the Keweenaw (60% chance). While some light lake effect snow showers are possible in the northwest wind snow belts late Tuesday night, expect them to end by Wednesday morning as ridging races back into the Upper Great Lakes.

Attention then turns towards a Clipper low that's expected to impact the Upper Peninsula Wednesday night into Friday. As the deepening Clipper low crosses the Northern Plains Wednesday night before arriving at or near Lake Superior Thursday, strong warm air advection from the Gulf will allow temperatures to rise back into the mid to upper 30s across the area on Thursday before strong temperature advection behind the low drops temperatures into the teens with the arrival of the polar air wrapped behind the Clipper. While we may see a light wintry mix of snow, sleet, freezing rain, and/or rain Wednesday night/early Thursday morning, thinking the main precip-type will be light rainfall Thursday along the initial cold front. However, as the polar air behind the low brings lake enhanced snowfall back across the area late Thursday from west to east, we may see a flash freeze setup as the rainfall and snow melt from earlier in the day move from above freezing air to WELL below freezing air (again, think of going from mid-30s to mid-teens in a 6 hour period!). Thus, while lake enhanced snowfall accumulations aren't projected to be too much (probably a few inches over the north wind snow belts), there may be some ice that develops rapidly over the U.P.'s roadways late Thursday afternoon through Thursday night, with some snow mixed within the ice (especially closer to Lake Superior). In addition to the icing concerns Thursday is also the wind threat; with the low being around 986mb by the time it moves through Lake Superior on Thursday, the strong pressure gradient and temperature advection could allow strong southwest winds Thursday morning before the cold air advection from behind the low whips-up northwest winds potentially as high as 50 mph across the Keweenaw and along the Lake Superior shoreline (up to around a 40% chance according to the latest NBM). These strong winds, in conjunction with any icing that occurs, could bring some power outages and minor lakeshore flooding and beach erosion to the Lake Superior shoreline late Thursday into Friday morning. Keep an eye on the forecast on this robust Clipper system for Thursday as the situation still remains fluid at this time.

The ridge and Clipper combo continues into this upcoming weekend as temperatures return closer to normal. As we move into next week, more baroclinic flow is expected in the mid to upper levels; however, confidence in this is fairly low at this time as this pattern is still several days out. If it comes to fruition though, we can expect some weak disturbances to bring some precipitation, mainly in the form of snowfall, over us from time-to-time as we approach the Christmas holiday.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 626 AM EST Sun Dec 14 2025

Lake effect snow showers will gradually diminish this morning at all terminals, slowest to end at KCMX. As it does, expect IFR/LIFR conditions at KCMX/KIWD and MVFR at KSAW to improve to VFR and winds to remain light into the evening. Tonight, another wave will move through Upper Michigan, potentially bringing snow, low level wind shear, and gusty winds. KCMX/KSAW are most likely to see snow, but confidence isn't high at KSAW, so a prob30 was included. Low level wind shear is most likely at KIWD for a few hours tonight beginning around 4z.

MARINE

Issued at 328 AM EST Sun Dec 14 2025

Northwest to north-northwest gales to 35 knots over the east-central lake and heavy freezing spray across the lake early this morning die down late this morning as ridging builds into the region today; winds die down to 20 knots or less over the east half of the lake by this early evening as the peak of the ridge moves through the lake. However, immediately behind the peak of the ridge, another Clipper low approaching the area tonight will allow winds out of the southwest to increase over the west half of the lake late this afternoon through late tonight ahead of its arrival, with southwest gales of 35 to 40 knots expected by late tonight (mainly across the western half, although some gale force gusts to 35 knots are also expected over the eastern lake late tonight into early Monday morning); in addition to the gales, heavy freezing spray is also expected over the far western lake tonight. Behind the Clipper on Monday, expect the winds to veer and weaken with time, becoming northwest to 20 to 25 knots over the eastern half of the lake by Monday afternoon before weakening further to 20 knots or less by Monday night as a weak ridge moves into the region.

As another Clipper moves through northern Ontario on Tuesday, expect the winds to once again pick up from the southwest Tuesday morning, potentially having gales up to 40 knots across much of the lake by the afternoon hours (30% chance). As the cold front of the Clipper moves through late Tuesday and Tuesday night, northwest winds in the cold air advection could gale up to 40 knots once more, with the highest chances over the eastern half of the lake (40 to 50% chance); some moderate freezing spray may also return behind the cold front. Winds weaken once again to 20 knots or less Wednesday as another ridge passes through the area.

The strongest winds of the forecast period are projected to occur Wednesday night through Thursday ahead of and immediately behind a strong Clipper low moving through the Northern Plains Wednesday night before traversing Lake Superior on Thursday. Winds increase from the south Wednesday night, with gales up to 40 knots possible lake-wide ahead of the low's arrival (up to 30% chance in the west and 40% chance in the east). As the strong temperature and pressure gradient immediately behind the low crosses the lake Thursday, the Arctic air wrapped around the low could allow west to northwest storm force winds up to 50 knots to move across the lake Thursday into Thursday evening (up to 25% chance according to the NBM); should this be realized, also expect a return of heavy freezing spray across the lake. As a stout high pressure ridge moves into the Upper Great Lakes on Friday, we can expect the winds to return back down to around 20 knots or less.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory until 10 AM EST this morning for MIZ006-085.

Winter Weather Advisory until 7 AM EST this morning for MIZ007.

Lake Superior... Heavy Freezing Spray Warning from 7 PM EST /6 PM CST/ this evening to 4 AM EST /3 AM CST/ Monday for LSZ162.

Gale Warning from 11 PM EST /10 PM CST/ this evening to 7 AM EST /6 AM CST/ Monday for LSZ162-263-264.

Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ this morning for LSZ240>245-248>251-263>267.

Gale Warning until 7 AM EST this morning for LSZ244>246- 248>251-264>267.

Lake Michigan... Heavy Freezing Spray Warning from 2 AM to 9 AM EST Monday for LMZ221.