textproduct: Marquette

KEY MESSAGES

- Snow showers and strong winds will diminish today.

- Additional snow accumulations of 1 to 5 inches are expected downwind of Lake Superior through this afternoon, with the higher amounts expected across Alger County.

- Light snow tonight through Wednesday may yield a widespread 1 to 2 inches across Upper Michigan.

DISCUSSION

Issued at 230 AM EDT Tue Mar 17 2026

Lake effect snow has stretched downwind of Lake Superior tonight thanks to continued cyclonic flow and 850mb temps near -21C, per SPC mesoanalysis, atop a mostly ice free Lake Superior. Radar reflectivities highlight a few stronger bands mixed within the traditional north wind snowbelts over Marquette and Alger counties. With elevated winds of 30 to 40 mph still being observed in many of these locations, blowing and drifting snow have continued to support hazardous conditions outside. For areas removed from these snow showers across the south-central and parts of the interior west half, clear skies and lighter winds of 5 to 20 mph have established themselves. Temperatures so far have fallen into the single digits and low teens across the region, with wind chill values being calculated near -10F in the coldest spots.

RAP analysis currently highlights sprawling ridging across middle North America. Today, this will gradually press eastward into the Mississippi River basin and the Great Lakes, with the ridge axis pressing through the forecast area by afternoon. This will result in continued lake effect snow downwind of Lake Superior today, but a gradual diminishing trend in the snow intensity and coverage. Current projections are for an additional 1 or 2 inches in the west/Keweenaw and 1 to 5 inches central/east through 0z Wednesday. Most of this is anticipated this morning. Lightening winds are also anticipated, with lakeshore areas falling below 30 mph near or before noon. Given the trend and the timing of inherited Blizzard Warnings, opted to downgrade these to Winter Weather Advisories through 12z.

Wednesday through Friday, the pattern across CONUS will involved stout mid-upper level ridging across western CONUS/Canada with broad longwave troughing gradually shifting off into the Atlantic. This will support northwest flow aloft over the Great Lakes. Within this flow, a few different impulses will dive through the region. The general consensus is that the first wave will come tonight when a swath of isentropically forced snow moves northwest to southeast through the forecast area. Greatest forcing with this is anticipated to remain to our south, but enough moisture should still support widespread 1 to 2 inches of snow tonight through Wednesday. Temperatures are anticipated to warm into the 30s for most of the region, with low 30s east and upper 40s west. All other impulses afterwards lack much temporal and geographic consistency in the guidance packages. Given this though, it does appear the next wave could dive into the Upper Midwest/Great Lakes region Wednesday night and Thursday and the another Thursday night/Friday. Should either of these move over the forecast area, impacts are not anticipated. The warming airmass may also support precip type to be rain in some locations, especially if these align with daytime heating when we warm into the upper 30s to mid 40s Thursday and Friday.

Late Friday, a more notable shortwave rounds the ridge top, exiting into the northern Plains late Saturday. There is considerable uncertainty on when and where the system will track, but should it track through the forecast area, both widespread snow and widespread a rain to snow transition would be on the table.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 138 AM EDT Tue Mar 17 2026

With the historic winter storm lifting out of the Great Lakes region, broadly improving conditions are being observed as only lighter lake effect snow is affecting SAW and CMX/IWD are clearing out, though occasionally gusty conditions have created occasional BLSN at CMX and will continue to do so on a temporary basis. Winds at all sites will weaken and become more westerly and southerly over time. SAW finally emerges from the lake effect later this morning, becoming VFR by the afternoon.

MARINE

Issued at 230 AM EDT Tue Mar 17 2026

Conditions on Lake Superior will continue to improve today as high pressure builds over the area, resulting in decreasing winds. With this in mind, inherited Gale Warnings will fall off this morning, with Heavy Freezing Spray Warnings through mid-afternoon. High pressure moving through the region will allow winds to become southwest and southerly this evening and tonight, increasing to 20- 30kts after midnight. Strongest winds are anticipated east of the Keweenaw Peninsula through Wednesday. The remainder of the work week favors weaker systems with limited wind response. The next chance for lakewide winds into the 20-30 kt range or greater is over the coming weekend, but there is considerable uncertainty in where the responsible system will track.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Lakeshore Flood Warning until 8 AM EDT this morning for MIZ006.

Winter Weather Advisory until 8 AM EDT this morning for MIZ006- 007-085.

Lake Superior... Heavy Freezing Spray Warning until 2 PM EDT /1 PM CDT/ this afternoon for LSZ240>248-263>265.

Gale Warning until 8 AM EDT this morning for LSZ243>251- 264>267.

Heavy Freezing Spray Warning until 5 PM EDT this afternoon for LSZ249>251-266-267.

Lake Michigan... None.