textproduct: Marquette

KEY MESSAGES

- Light to moderate snowfall is expected tonight, mainly across the west half where areas of high terrain could see an additional 2-4", less elsewhere.

- Dry weather Tuesday ahead of yet another active period, though rain looks more likely for the back half of next week.

- Gales of 35-40 kts are expected across the east half of Lake Superior late tonight through Sunday morning

DISCUSSION

Issued at 236 PM EDT Sat Apr 4 2026

Afternoon GOES satellite imagery reveals a closed low inching eastward across Minnesota towards Upper Michigan. The systems mid- level occluded front has pressed through the western two thirds of the UP, touching off some light mixed (mostly sleet/rain) showers which will fully depart the east half over the next several hours. With little to no additional ice accumulations expected tonight, have opted to let the Ice Storm Warnings expire. No additional headlines are planned at this time. Otherwise, a notable dry slot will keep the area mostly dry through this afternoon before the deformation band / wrap around snow makes its way into the west half tonight as the system translates northeast into Ontario/Quebec. There, with midlevel temps falling between -8 and -10C and surface obs below 32F, wet snow is the expected precip type. This mornings HREF suggests high chance (>75%) for at least 3" of lake/orographic enhanced snow across the western high terrain of the Porkies, Keweenaw Spine, and Baraga Co by Sunday sunrise. Elsewhere, an inch or less is most likely.

Another pair of weak shortwaves will pivot around the eastern Canada/Hudson Bay trough tomorrow and Monday. Global deterministic models struggle to resolve a discrete surface low with these features, but a weak surface trough appears to transit through the area, and as it is embedded within cool northwesterly background flow, snow will be the dominant precipitation type tomorrow and Monday, though a few rain showers mixing in to typical warm spots (Menominee, for instance) cannot be ruled out. Temperatures aloft become unsuitable for lake effect snow tomorrow, but behind the later shortwave on Monday, 850mb temps fall to around -17C, which is more than enough to support a period of lake effect snow showers, which look to maximize in intensity around Monday morning with the west half seeing perhaps up to 2"/6hr snow rates.

Stout high pressure to near 1035 mb then establishes itself over the Upper Great Lakes Tuesday, bringing the driest day of the forecast period to the region (from a "chance of precipitation" perspective). This kicks off a warming trend in the high temperatures, with most of the UP breaking freezing on Tuesday and the proceeding days seeing many high temps in the 40s.

The break in active weather is brief. A closed low that is currently spinning over Bethel, Alaska will pivot through the Canadian Rockies by Tuesday afternoon, becoming positioned just upstream of the Upper Great Lakes by Wednesday afternoon. This system is expected to bring some Pacific moisture as well as establish at least a weak Gulf connection as it passes, providing ample moisture for rain to occur. Uncertainty then grows significantly as spread increases drastically, however the general pattern looks to continue to be rainy, including conditions over the Southeast to Southern Plains being more conducive to advect more Gulf moisture to the Upper Midwest. Attention will turn quickly to hydrology in this period as the snowpack has not only persisted, but has retained much of the liquid precipitation (freezing rain and rain) of recent as well as being reinforced by the recent (and will be reinforced by upcoming) wet snow/sleet. Should warm and moist southerly winds help snowmelt in addition to heavy rain occur (CPC highlights a risk for heavy rain around the 11th-13th), flooding will be a concern, though spread is so high at this point that any details will be muddy at best. For now, just something to monitor in the outlook.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 718 PM EDT Sat Apr 4 2026

IFR/LIFR ceilings persist at all terminals tonight with plenty of low- level moisture and a low pressure system moving through the Great Lakes. A lingering wintry mix at IWD/CMX changes over to snow over the next couple of hours as colder air aloft moves in, but lingering snow showers should wrap up into Sunday moring. A gradual improvement to VFR is expected into Sunday afternoon at all terminals. Northwest winds increase behind a cold front tonight with gusts up to 20 kts at IWD, 25 kts at SAW, and 30 kts at CMX into Sunday morning. Winds begin to taper down Sunday afternoon.

MARINE

Issued at 236 PM EDT Sat Apr 4 2026

Sub-gale force easterlies this afternoon veer N then NW tonight into early Sunday morning as the current low pressure system placed just south of Lake Superior presses northeast into Ontario/Quebec. Modest pressure rises and cold air advection on the northwest flank of this departing low will reintroduce gales 35-40 kts across the east half of the lake after midnight lasting through sunrise before falling below gales area wide between 12-15z. Significant wave heights during this timeframe will build between 8 and 12 feet, highest near the lakeshores between Munising and Grand Marias. Have opted to introduce a new Gale Warning for the open waters and nearshores between the Keweenaw and Whitefish Point.

A weak disturbance passing overhead Sunday will not be strong enough to keep winds from falling below 20 kt and waves will relax to below 4 ft lakewide by Sunday night. A slightly stronger disturbance on Monday will drive up to 70% chances of northerly to northwesterly gales on Monday. Should these gale occur and drive waves of 8-12 ft, the cool air behind the disturbance will bring conditions that support moderate to heavy freezing spray Monday and Monday night. High pressure moving into the Upper Great Lakes Tuesday will bring wind gusts below 20 kt and waves below 4 ft, though relief will be short lived. A system approaching from the Canadian Rockies will bring chances of gales Wednesday evening of around 50%, and the active pattern continues into the latter part of the week, though uncertainty in the details increases dramatically.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning from 3 AM to 10 AM EDT Sunday for LSZ244-245- 248>251-265>267.

Lake Michigan... None.