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KEY MESSAGES

- Lake effect snow and wind gusts up to 35 mph continue tonight over eastern upper and northern lower resulting in very low visibilities under bands of heavy snow. Additional accumulations of 1 to 6 inches with locally higher amounts in snowbelt areas

- Lake effect snow lingers through Sunday as winds turn north and weaken, moving the focus of snow to Grand Traverse Bay and south through the day.

- The next system approaches quickly late Sunday into Monday, returning snow chances to most of northern MI and warming temperatures into the 20s

- Temperatures warm above freezing starting Tuesday with unsettled weather continuing

SHORT TERM /THROUGH SUNDAY/

Issued at 234 PM EST Sat Dec 13 2025

Current radar and satellite depict widespread lake effect snow showers over most of the state. Under generally west winds a few organized bands of heavier snow have been able to form; one running parallel to the south side of Little Traverse Bay, another along M-32, a more transient band just south of that one and multiband action up over the southern end of Lk Superior. Bands of light to moderate snow exist elsewhere. Under these heavier bands, very cold profiles aloft (single digit surface temps near the surface) hug the DGZ close to the surface - resulting in small flakes or a powdery snow characteristic. SLRs were initially higher this morning (before the coldest air aloft moved in) when it first started to snow (some ratios were 20:1), however these have been trending lower (15:1 for 18Z ob). This environment has led to quick drops in visibility as the powdery snow gets blown in the winds (gusts up to 25 to 30 mph) or under heavier snow bands. Around 2 to 4 inches with a couple of reports up to 4 to 6 inches have fallen over the advised areas so far.

Above our heads, the upper level closed low continues to spin over northern Lk Superior and Ontario CAN this afternoon. At this time, winds remain unidirectional through the column as west winds aloft are a product of some amplification on the west and east side of the upper low. The closed low will shift to the southeast, moving the western lobe of energy over northern MI over the next 12 hours and resulting in second peak intensity of snowfall and a continuation of gusty winds. LL and near surface winds will trend north during this time, becoming northwest this evening (6 to 8 PM ET). The focus of heavier lake effect snow bands will move under the changing winds, currently seen as heavier snow bands have finally moved over the SOO this afternoon. Heavier bands will focus more over the typical snow belt areas of northern lower (big 5) tonight and will likely stretch farther inland as the upper forcing aids generating this second peak of intensity. Times of very poor visibilities and quick accumulations of snow on roads lead to hazardous driving conditions under heavier snow.

Sunday morning, winds turn north to north-northwest and remain elevated. This focuses the remaining lake effect snow bands over Grand Traverse Bay and areas south. These lake effect snow bands will likely linger into the mid day hours of Sunday as residual surface features reach the same area (lake aggregate troughing rotates south from the U.P.).

LL temperatures will warm during the day Sunday as winds weaken. Snow showers should weaken during the later half of the day, with high temperatures reaching into the 20s.

Current thoughts are that snowfall amounts will be spreading over a larger area as winds gradually shift tonight, leading to most of NW lower seeing an additional 1-6 inches tonight and Sunday. SLRs will rise again as LL temperatures trend up Sunday, and forcing can still push the DGZ saturation into a decent depth. Due to the possibility of lingering surface forcing, spots near Kalkaska and Grand Traverse county could see some locally higher amounts of +6 inches during this time. Snow showers will be more robust over eastern upper due to this lake aggregate troughing moving south over western Chippewa county as it is still organized, resulting in additional snow amounts of 5 to 8 inches over areas adjacent and south of Whitefish bay. Locally higher amounts of +10" will be possible over western Chippewa county.

LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/

Issued at 234 PM EST Sat Dec 13 2025

Winds turn southwest late Sunday night as clipper system quickly approaches from the northwest. Winds aloft remain northwest, however the upper level PNA pattern over the CONUS will begin to break down/weaken. A weak upper shortwave will accompany this next system, which will spread light to moderate snow over the CWA early Monday. LL winds shift west/northwest late Monday as some lake effect remains possible. Accumulations from this will remain on the lighter side, as the time window is fairly short and forcing isn't ideal or vertically aligned. Intial thoughts for total snow amounts are T-1 inches for most of northern lower, with 1-4 inches near the tip of the mitt and areas of eastern upper.

Southwest winds return late Monday into Tuesday as 850 temperatures warm to above 0C. Rain and snow will be possible as another system moves across southern CAN Tuesday into Wednesday. There is potential for deep moisture advection towards the great lakes region late Wednesday into Thursday. Warmer temperatures (surface temperatures above freezing), higher surface dew point temps (above freezing Tds will eat away at the snow pack), and rain chances are all possible Thursday with a stronger system at the end of the work week. An amplified system that can advect warm and moist air this far north will also shunt cold, dry CAN air over the same area Friday into the weekend. Stay tuned for more details.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 554 PM EST Sat Dec 13 2025

Lake effect snows will continue to bring MVFR to even periods of IFR conditions at times tonight, with most notable impacts at those western taf locations. May also see a more transient band of snow work south across KCIU and KAPN tonight, perhaps even bringing those locations a brief period of IFR conditions. Lake snows will focus closer to KTVC and KMBL with time later tonight and Sunday morning, with other locations likely seeing just some lake effect clouds. Improving conditions expected at all locations heading through Sunday afternoon. Gusty winds will continue as they gradually veer more northwest with time.

APX WATCHES/WARNINGS/ADVISORIES

MI...Winter Weather Advisory until 7 AM EST Sunday for MIZ016-017- 099. Winter Weather Advisory until 1 PM EST Sunday for MIZ020>022- 025>028-031>033. Winter Storm Warning until 5 AM EST Sunday for MIZ086-087. MARINE...Small Craft Advisory until 5 PM EST Sunday for LHZ345>349. Small Craft Advisory until 5 PM EST Sunday for LMZ323-341-342- 344>346. Small Craft Advisory until 11 PM EST this evening for LSZ321- 322.