textproduct: Marquette

KEY MESSAGES

- Ice Storm Warnings remain in effect this morning to early afternoon with ice accumulations up to 0.4" in the interior west. Power outages and tree damage are possible.

- A rain/snow mix tonight gives way to periods of light to moderate snowfall Sunday and Monday.

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

- Gales of around 35 kts are expected across much of the central and western waters of Lake Superior today.

DISCUSSION

Issued at 409 AM EDT Sat Apr 4 2026

Early morning KMQT radar returns show a shield of precipitation overspreading the UP gradually from the south and southwest. METARs show precip types have been somewhat mixed thus far, with periods of UP (probably sleet) and -FZRA reported at sites such as IMT. Just across the state line, LNL and EGV have reported -SN as well, and with some mesonet sites above freezing, some RA is also likely present as well. Aloft, a vertically stacked closed low is evident over South Dakota per RAP analysis, with a mature surface cyclone evident on surface analysis and low level GOES-East water vapor imagery. A complex forecast continues today, as subtle temperature shifts can lead to massive forecast shifts, especially in the ice accumulation forecast. HREF FRAM accumulation goes wild with the ice accumulation, with mean rates in excess of 0.2"/6hr for some areas for much of the morning. However, when similar algorithms are run with temperature profiles more resembling the consensus of global models, which show a warmer surface profile (especially for Alger/Schoolcraft/Delta counties), ice totals are much less. This forecast package will reflect a bit of a compromise, with ice totals by 18Z of around 0.25", +/- 0.15" (highest interior west, lowest east and along the shores of the Great Lakes). Therefore, the Ice Storm Warnings will continue apace, though they day shift may consider keeping the eastern Ice Storm Warning going until 18Z with the western warning if the cooler temperatures at the surface prevails. One complicating factor may be the track and residence time of the dry slot, which at 06Z was evident on water vapor imagery over Iowa and Minnesota just east of the center of the 700mb low center. The day shift today will have to continue to track this feature and see if it brings an early end to the heaviest of the freezing rain.

This afternoon and evening, temperatures warming to above freezing will bring most of the precip to being just a cold rain, and as the surface low pushes through, the cool northerlies at the surface and aloft will erode the cold nose and bring the surface sub-freezing. This will translate to a cleaner transition to rain or a rain/snow mix instead of the freezing rain and sleet of earlier. As 850mb temperatures drop to around the -10C mark, some orographic/lake enhanced to light lake effect snow showers are ~60% likely, especially for areas where Lake Superior is to the northwest, as that is where the surface flow will be oriented. The HREF suggests that the spine of the Keweenaw and the vicinity of Mount Arvon will see an additional 1-2 inches of snow tonight, though accumulations elsewhere look to be around a half inch or less.

Another pair of weak shortwaves will pivot around the eastern Canada/Hudson Bay trough Sunday 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 Sunday 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 on Sunday, 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 /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 742 AM EDT Sat Apr 4 2026

IFR and LIFR conditions are expected into this evening as a low pressure moves trough the Upper Great Lakes. The main contributor to LIFR will be low cigs though upslope fog will also develop, especially at SAW with vsby falling to 1/2 mile at times. Scattered precip will also continue over the U.P. in the from of -fzra and/or -pl but will transition to -shsn this afternoon into the evening as a cold front pushes through. Behind the front expect gusty nw winds to 25kt along with -shsn, with the best chance for -shsn at CMX. Conditions should improve to MVFR late tonight into Sunday morning with slightly drier air near the sfc helping to lift cigs.

MARINE

Issued at 409 AM EDT Sat Apr 4 2026

An approaching mature mid-latitude cyclone will bring easterly gusts to near 35 kt for much of Lake Superior this morning to early afternoon, with the long-duration easterlies driving waves of 8-11 ft for all expect the far eastern waters, though north of the Apostle Islands, some 12+ ft waves may be observed. The low passing to the south will shift the winds to be out of the northwest by tonight, bringing wind gusts of around 25 kt (expect for a brief period of gale force gusts to the east-central lake overnight into Sunday morning). The shifting wind direction will help waves settle to 5-8 ft tonight before increasing in the east half to near 12 ft Sunday morning (higher in the southeast). 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... Winter Storm Warning until 2 PM EDT this afternoon for MIZ001- 003.

Ice Storm Warning until 2 PM EDT /1 PM CDT/ this afternoon for MIZ002-004-005-009>012-084.

Ice Storm Warning until 11 AM EDT this morning for MIZ006-007- 013-014-085.

Lake Superior... Gale Warning until 2 PM EDT /1 PM CDT/ this afternoon for LSZ162-244-245-263>266.

Lake Michigan... None.