textproduct: Marquette

KEY MESSAGES

- Multiple gale events could be seen across Lake Superior this week into this weekend, with another one happening as soon as tonight. Storm Force gusts up to 50 knots are possible late Thursday (20% chance), with Heavy Freezing Spray being seen late Thursday into Friday morning.

- The strong winds across the Great Lakes this week could create times of minor lakeshore flooding and beach erosion. See any pertinent Lakeshore Flood Advisories for more info.

- A strong Clipper low could bring high winds, a flash freeze, and/or several inches of snowfall across the area Thursday through Thursday night. Driving conditions could be difficult at times, especially in the north wind snow belts Thursday night.

DISCUSSION

Issued at 338 AM EST Wed Dec 17 2025

Temperatures last night generally continued to climb across the area during the early evening hours, with the warmest temperatures yesterday being found mainly between sunset and just after midnight. Overall, expect the highs yesterday (and today for that matter for some areas) to have occurred during the overnight hours last night/early this morning. Behind a cold front of a low lifting from Hudson Bay into far northern Quebec this morning, expect temperatures to continue dropping, with the lows this morning being realized around/to just after sunrise as cold air advection continues until the late morning hours. This cold air advection may bring some light drizzle/freezing drizzle/snow across the northwest wind snow belts this morning before transitioning to all snow and becoming relegated to just the eastern U.P. late this morning as high pressure ridging moves through the region today. With ridging moving in today, expect a respite in the windy conditions across the U.P. later this morning through this afternoon, as Ontonagon, Copper Harbor, and Houghton airport got to 56, 53, and 51 mph respectively with the passage of the cold front early this morning. As the lake effect cloud cover erodes away and warm air advection starts to move back in late this afternoon, expect temperatures to begin rising towards 32F, with some of the downslopes potentially returning to the mid 30s near sunset.

As a robust Clipper system travels through the Northern Plains tonight and through Lake Superior Thursday, expect warm air advection, aided by an 80+ knot LLJ (wow!), to slowly warm temperatures once again across the U.P. as the low approaches. While mixing into this LLJ looks to be pretty restricted given that most CAMs don't have the best lapse rates in the boundary layer, the NBM is bringing around a 50% chance that south to southwest winds will gust up to 45 mph or more in the higher elevations and downslopes of Baraga, Marquette, and Alger counties. Should chances for the winds of 45+ mph improve today, a Wind Advisory may need to be hoisted for these counties for tonight. As for the other portions of the U.P., expect south to southwesterly winds of 30 to 40 mph throughout, with potentially some gusts up to 45 mph near the mouth of the Montreal River early tonight. In addition, a shortwave low lifting from the Central Plains tonight looks to phase with the incoming Clipper late tonight through Thursday. As this occurs, we may see some a wintry mix of drizzle, freezing drizzle, and snow develop across the U.P. late tonight through Thursday morning as the forcing with this weaker shortwave phasing with the Clipper looks to bring moisture over us throughout the daylight hours on Thursday. If we do see any freezing drizzle or snowfall late tonight through Thursday morning, expect accumulations to be limited to a glaze and/or dusting, and mainly across the far west and Keweenaw. Thus, we could see some limited icing impacts on the roads Thursday morning before temperatures warm above freezing on any untreated roads, but that (thankfully) looks to be about it impacts-wise from icing; just be careful if you're driving Thursday morning as the winds and potential slick spots on untreated roads could create an accident.

As the around 986mb Clipper low moves through Lake Superior on Thursday, we can expect a transition over to mainly drizzle/rain across most of the area, although the far west and Keweenaw could a transition over to snowfall by late in the morning (if the Keweenaw even transitions from snow beforehand) as the Clipper passes by and brings colder air back in. While the Clipper passes through Lake Superior on Thursday, we can expect winds to slacken across our area significantly, with gusts dropping down closer 20 mph. Indeed, it's possible that we will see the dry slot of the Clipper low bring a cessation to precipitation throughout most of the area Thursday, with many of the CAMs highlighting this possibility (lowest chance of this occurring over the Keweenaw and far west). However, if precipitation does continue, expect it to be light as the dry layer of the Clipper interacts with the moisture coming in from the shortwave being phased in. As the main core of Arctic air cycles into the region Thursday night, expect a transition over to all snowfall from west to east with time. In addition, temperatures around freezing across the area will rapidly decrease with this incoming Arctic air. Thus, there may be some black ice that forms on the roads due to Thursday's above freezing temperatures inducing melting and precipitation that occurred before the Arctic blast's arrival. While we think the severity of a flash freeze is decreasing as the forecast model trend has the rapid temperature change further and further in time from the precipitation on Thursday, it's still a potential threat worth messaging as it, in conjunction with the other hazards, could create hazardous driving conditions across the Upper Peninsula Thursday night. Speaking of the other hazards, expect the robust temperature advection associated with the incoming Arctic airmass to bring strong northerly winds and moderate to potentially heavy (1/2 per hour or greater snowfall rates) lake enhanced snow showers to the north wind snow belts Thursday night. While initially wet, the snowfall will become rather fluffy rapidly as temperatures shift significantly colder, with most of the atmospheric profile in the lower to mid-levels becoming relegated to the DGZ. Thus, given the high northerly winds of potentially 40 to 50 mph and quickly accumulating snowfall over the north wind belts becoming fluffy rather fast, blowing snow will be another concern Thursday night into Friday morning along the Lake Superior shoreline. With guidance now converging on a track for the sfc Clipper low Thursday, confidence is increasing that the Keweenaw will see several inches of snowfall from at least late Thursday afternoon into Friday morning. Other areas in the north wind snow belts may also see a few inches, especially over the west where the transition to snowfall looks to occur sooner. Outside of the north wind snow belts, up to around an inch may be seen before the transition over to pure lake effect snow in the north-northwest wind snow belts Friday morning. Overall, driving conditions will range from hazardous to potentially dangerous over the north wind snow belts Thursday night, with the worst conditions expected in the Keweenaw as quickly accumulating snowfall and blowing snow are expected to make roads slick and visibilities low; the strong winds may also make controlling the car extra difficult, especially in areas of greatly changing wind speed. Therefore, it may be wise to avoid traveling if you can help it Thursday night, at least until conditions improve Friday morning.

Expect the lake effect snow over the north-northwest wind snow belts to dwindle away with time Friday as high pressure ridging moves back over the region throughout the day. While there may be another fluffy inch or two seen over the eastern U.P. (where there is a longer fetch over Lake Superior), the ridging looks to keep additional snow totals at less than an inch (if even that) across the rest of the U.P.

The next Clipper system looks to bring additional snowfall across the area around Saturday. With another shortwave looking to phase with it, a few inches may be realized over us as the parent Clipper low moves from the Canadian Prairies towards the St. Lawrence Seaway this weekend. This may cause some travel concerns during the day Saturday; greater analysis into this system will occur once we get through the robust Clipper low impacting us tonight through Thursday evening. While some light northwest wind lake effect snow showers may be seen behind it into Sunday, expect the impacts from the lake effect snow to be no more than nuisance. Warmer than normal temperatures are expected to impact the U.P. next week as high pressure ridging increases over the central CONUS in the mid to upper levels.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1231 PM EST Wed Dec 17 2025

Clearing skies are allowing for a brief return to VFR this afternoon with lighter SW winds. A very strong low level jet will move overhead this evening, supporting occasional gusts to 25-35 knots at all terminals overnight while 50-55 knots exists at 2k feet. The same flow will result in increasing moisture and warmer air. This will support MVFR ceilings developing late tonight along with the potential for precip. Given the warm inversion aloft and questions about how quickly the low level portion of the column will warm, prob30s for a mix of -fzrasn was included at all terminals for most of the night. After 12Z, there is better confidence for -shrasn to develop at SAW and CMX, with a lowering to IFR expected at those terminals.

MARINE

Issued at 349 AM EST Wed Dec 17 2025

Northwest gales up to 40 knots early this morning drop down to 20 knots or less again by around noon EST today as high pressure ridging skirts through the region. However, a robust Clipper system moving through the Northern Plains tonight and moving through Lake Superior on Thursday looks to increase winds from the south/southwest this afternoon through this evening, with gales up to 45 knots potentially being seen across mainly the eastern half of the lake late tonight (up to around a 70% chance according to the latest REFS). We may struggle to reach gales over the western half of the lake tonight, save for near the downslopes by Wisconsin and Upper Michigan, as mixing into the LLJ doesn't look as good (only up to around a 50% chance for gales in the west half). Nevertheless, winds look to slacken as the Clipper low moves through on Thursday, generally ranging from around 20 to 30 knots around the center of the low throughout the day. We could see significant wave heights as high as 13 feet over the eastern open lake early Thursday morning before this happens; however, once the low starts pushing through on Thursday, expect the waves to drop down closer to the 3 to 6 foot range.

Once the Arctic air wrapped around the Clipper low dives over Lake Superior late Thursday into Thursday evening, expect the winds to rapidly accelerate to northerly gales of 35 to 45 knots; some storm force gusts to 50 knots could even be seen over the north central and eastern lake (around 20% chance or less). In addition, the high winds look to kick up heavy freezing spray across the lake late Thursday into Friday morning; expect a Heavy Freezing Spray Warning in the future. Expect the significant wave heights with this high- end gale event to soar into the mid to upper teens across the central and eastern lake; a few waves over 20 ft could be seen east of the Keweenaw Thursday night. As high pressure ridging begins to return late Thursday night and continues to push into the region on Friday, expect the gales and heavy freezing spray threats to die down by around noon EST; winds are currently projected to drop below 20 knots or less once again by Friday evening.

With the active pattern continuing through this weekend though, don't expect the light winds to stay all that long. Another Clipper low moving from the Canadian Prairies towards the St. Lawrence Seaway this weekend looks to potentially bring southerly gales back to Lake Superior Friday night into Saturday morning (up to a 50% chance, highest east). As the cold air behind the low moves through on Saturday and Saturday evening, we could see westerly gales once again across the lake as well as a return of heavy freezing spray conditions (up to 40 to 60% chance for gales). However, a high pressure moving from the Northern Plains into the Upper Midwest late this weekend looks to drop the winds back down to 20 knots or less again by Sunday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning from 1 PM EST /noon CST/ Thursday to 1 AM EST /midnight CST/ Friday for LSZ162.

Gale Warning from 10 PM EST /9 PM CST/ this evening to 4 AM EST /3 AM CST/ Thursday for LSZ240-241.

Gale Warning from 1 PM Thursday to 10 AM EST Friday for LSZ242>246-263-264.

Gale Warning from 7 PM this evening to 10 AM EST Friday for LSZ247>251-265>267.

Lake Michigan... Gale Warning from 10 PM this evening to 7 AM EST Thursday for LMZ221-248-250.