textproduct: Marquette

KEY MESSAGES

- Lake effect snow showers will continue late this afternoon over the Keweenaw Peninsula. Snowfall may increase in intensity in and north of Houghton beginning during this afternoon's commuting period and through tonight. Winter Weather Advisories remain in effect through Wednesday morning.

- Coldest air of the season will create a period of below zero temperatures from Thursday night through at least Saturday morning across most of Upper Michigan. Temperatures below -15F and wind chills near -40 F are likely (west). An Extreme Cold Watch has been issued for western and central Upper Michigan.

DISCUSSION

Issued at 406 PM EST Tue Jan 20 2026

Synoptic setup this afternoon consists of a stationary low pressure system over the Hudson Bay with waves rotating around the mid-level flow. At the surface, high pressure is encompassing much of the southeastern U.S. This pattern has been conducive to extremely cold high temperatures across the U.P. this afternoon. Currently, ground-based obs across the area are reporting widespread temperatures in the single digits with the exception of low teens over the Keweenaw Peninsula. And, west- southwesterly winds continue to gust into the 20 to 25 mph range over the Keweenaw. This is also where a Winter Weather Advisory remains in place through Wednesday morning for persistent lake effect snow showers. CAMS continue to support an especially heavy band confined to the Calumuet-Copper Harbor corridor where snow amounts could top off in the 6 to 8 inch range by tomorrow morning. After a bit of a reprieve from the frigid temperatures tomorrow, highs in the teens, the main threat through the forecast period will be the extremely cold temperatures. The aforementioned low over the Hudson bay will shift southeastward across northern Ontario, bringing the coldest airmass of the year so far with it. This shift will commence tomorrow night as 850 mb temperatures drastically fall into the -20 to -25 degree range by Thursday morning. This will be accompanied by wind gusts of 20-30 mph Wednesday night into Thursday. This will push wind chill values near the Cold Weather Advisory mark for the far west Thursday morning. However, model guidance is still coming up a bit short of the -25 degree criteria, so held off on an advisory at this time. But, one could be issued with future forecast issuances. Further out, though, confidence was high enough to issue an Extreme Cold Watch for western and central Upper Michigan from Thursday evening through Saturday morning. By Friday morning, the far west could reach -40 degree wind chills with widespread -35 to -30 degree wind chills over the remainder of the western and central U.P. And, temperatures over these areas will not top off above zero until Sunday. Please exercise caution for this especially dangerous situation.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 639 PM EST Tue Jan 20 2026

Southwest winds lift lingering lake effect snow showers away from CMX. With winds tapering down to 7-10 kts tonight, blowing snow and vis restrictions are expected to improve there to MVFR by Wednesday morning. A disturbance late tonight may result in light snow showers preventing a full recovery to VFR at CMX during the period. Meanwhile, VFR at IWD persists into at least Wednesday morning and through early afternoon at SAW. The main system arrives Wednesday afternoon, bringing all sites down to MVFR/IFR at the end of the period.

MARINE

Issued at 406 PM EST Tue Jan 20 2026

Winds near 30 knots and isolated gale force gusts up to 35 knots (mainly east) will continue tonight. These lighten to near or below 20 knots by tomorrow morning. Then another elevated wind period returns Wednesday night, persisting into at least Saturday morning. Gales can't be ruled out, especially Thursday night through Friday over the east when instability peaks with the extreme cold airmass.

The risk for heavy freezing spray will continue tonight due to the cold air over the area and the elevated winds. Conditions improve tomorrow under the light winds, but return Wednesday night and continue through at least Saturday morning.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory until 7 AM EST Wednesday for MIZ001- 003.

Extreme Cold Watch from Thursday evening through Saturday afternoon for MIZ001>005-009>012-084.

Lake Superior... Heavy Freezing Spray Warning until 10 PM EST /9 PM CST/ this evening for LSZ240>244-263-264.

Heavy Freezing Spray Warning until 1 AM EST Wednesday for LSZ245>250-265-266.

Heavy Freezing Spray Warning until 7 AM EST Wednesday for LSZ251-267.

Lake Michigan... None.