textproduct: Marquette

KEY MESSAGES

- Weak clipper systems will provided light snow chances this weekend with lake effect snow following for the NW wind snowbelts.

- Gale Warnings are in effect for much of Lake Superior for anticipated southwest gusts 35-40 kts tonight through Friday morning.

- Colder than normal temperatures continue through the forecast. Expect wind chills below zero across much of the U.P. tonight.

DISCUSSION

Issued at 257 PM EST Thu Dec 4 2025

Early afternoon RAP analysis and GOES Satellite imagery reveals clearing skies overhead da Yoop as lake effect clouds/snow are starting to kick offshore with winds backing to the SW ahead of a low amplitude clipper. Present satellite loop shows this SW backing nearly complete in the west while lingering lake effect will likely persist in the east a bit longer. Overall, not expecting much in terms of additional snow accumulation more than an inch through this evening east of Munising. After a brief quiet period this afternoon and evening, the aforementioned low amplitude clipper works its way southeast across the northern Great Lakes tonight, swinging around the periphery of a nearly semi-permenant closed low hanging out in the Hudson Bay. Weak WAA/isentropic lift ahead of the clipper will be the forcing mechanism for light snow that is set to spread across the northern tier of the UP late tonight into tomorrow morning. Model QPF isn't too impressive, coming out between a trace to a tenth of an inch per 6 hours where lake effect/enhancement may provide a local boost in the Keweenaw and east. Combined with SLRs 15-20:1, this yields snow totals by tomorrow afternoon less than an inch across much of the central and western UP. Elsewhere, WSW flow may be able to sneak in 2-4" in the Copper Country, while 1-3" will be seen in the east, mainly from Luce county further into Chip/Mack. Snowfall may be thwarted by a dry boundary layer beginning to take shape as well as midlevel subsidence noted by forecast soundings. Additionally, SW winds will be on the increase tonight as the clipper's 40-50kt LLJ works its way overhead. SW gales 35-40 kts will be common on Lake Superior tonight before calming down around sunrise.

For those that miss out on the light snowfall tonight, don't worry! The pattern through the rest of the weekend and into the coming week is highly supportive of persistent NW flow aloft and embedded clipper trains skirting through the Midwest and Upper Great Lakes, the first of which quickly follows tomorrow night into Saturday morning. This one takes a slightly southern track through N Wisconsin, providing another round of light snow followed by a reinforced shot of cold air and light lake effect snow to the northwest wind snowbelts through the rest of the weekend. At this time, lake effect snow aims to be on the lighter side, potentially providing the NW wind snowbelts with an additional 1-3" (locally higher under stronger, more persistent bands) despite supportive delta-Ts pushing 25C given dry air within the boundary layer.

Looking further into the midweek period, operational models and their ensemble counterparts continue the NW flow aloft clipper train across the area, supporting additional periods of accumulating system and lake effect snow.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 702 PM EST Thu Dec 4 2025

VFR conditions will deteriorate at all TAF sites early tonight with the arrival of the next system. Look for deterioration to start first at IWD and CMX in the Fri 03-06Z time frame followed by SAW after Fri 06Z. Best chances for IFR or lower will be at CMX where lake enhancement will help to boost snowfall intensity. Nonetheless, cannot entirely rule out IFR at IWD as well. In addition, will carry a LLWS threat at IWD tonight as a 40-50 kt low level jet precedes the aforementioned clipper system. At the surface, southwesterly winds will gust to 30 to 35 kts at all TAF sites through Fri 09Z, decreasing toward daybreak. IFR/MVFR expected to persist through Friday morning at IWD and CMX, while SAW trends more toward MVFR/VFR late in TAF period.

MARINE

Issued at 257 PM EST Thu Dec 4 2025

Southwest winds ahead of the next Clipper Low will ramp up in the west this evening to gales of 35 kt, spreading across the rest of the lake up to 40 kt tonight. Freezing spray rates will be more moderate with the gale this evening through tomorrow. Waves quickly ramp up to 9-13 ft tonight for the open waters surrounding Isle Royale and Michipicoten Island. Tomorrow, wind gusts fall to near 20 kt and waves fall to near 4 ft. Saturday morning, post-frontal northwest winds will ramp up to 30 kt, with chances of a brief 35 kt gale around 40 percent. The weather pattern into next week looks to continue with periodic Clipper Lows that will bring either increased southwest winds ahead of it and/or gusty northwest winds in its wake.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning until 4 AM EST /3 AM CST/ Friday for LSZ162- 240>242-263.

Gale Warning until 7 AM EST Friday for LSZ243>251-264>267.

Lake Michigan... Gale Warning until 7 AM EST Friday for LMZ221-248-250.