textproduct: Marquette

KEY MESSAGES

- The threat for flooding continues, but will decrease through today as cooler weather continues, slowing snowmelt.

- Flurries/light snow showers are possible into tonight, mainly over the east half. Otherwise predominantly dry weather persists through the middle of next week.

- With the sfc drying out and temperatures increasing from Monday onwards, the chance for elevated fire weather conditions is beginning to increase from Monday to Wednesday.

- There is a 40-50% chance for south to southwesterly gales up to 40 knots over eastern Lake Superior Monday night.

DISCUSSION

Issued at 301 PM EDT Sun Apr 19 2026

Afternoon GOES water vapor imagery highlights the cold northwest flow overhead as a mid level trough progresses east over the Great Lakes/northern Ontario. High pressure sits beneath it, centered over the state lines between MN and the Dakotas. Further upstream, a closed low spins off the coast of the PAC NW where a ridge resides. This low will play a role in the late week forecast. SPC meso analysis shows 850mb temps between -16C and -13C over Lake Superior, coldest northeast. As a result of marginal delta-Ts and elevated lapse rates, LES and diurnal light snow showers/flurries have decorated the radar mosaic. Model soundings indicate limited moisture outside the DGZ alongside a high sun angle will keep accumulations limited to a few tenths at best, but a fluffy inch is possible over the east by Monday morning. Otherwise high pressure shifts southeast to Lower MI for Monday morning, tapering winds, drying out precip and helping clear cloud cover overnight. With the seasonably cold air aloft still in place and subsidence, overnight lows are anticipated below the NBM in the teens to low 20s, coldest interior. MOS guidance hints at a few spots dipping into the single digits in the west where skies clear out faster. NOHRSC model SWE change noted only trace amounts to 0.5 inches of SWE lost in the last 24 hours. Given the colder than normal temps through Monday morning, additional snowmelt will be limited, helping limit flooding concerns.

High pressure continues shifting east through Monday, increasing southerly flow and warming temps much closer to normal in the 40s to low 50s, warmest west. Increasing cloud cover from the west will help limit mixing, but model soundings still suggest southerly wind gusts reaching 20-25 mph by the evening ahead of an approaching cold front. Gusts up to 30 mph are expected where downslope flow is maximized, particularly near eastern Lake Superior. Mixing will broadly drop RHs into the 20-30% range, save for low 30s near the lakeshores. Can't rule out some interior western spots reaching upper teens for min RH. The combination yields elevated fire weather conditions. What will help limit overall concern is recent precipitation and snowmelt keeping soil moistures up. The lack of moisture should prevent any precipitation from reaching the ground Monday night into Tuesday when a surface low well to the north sends a cold front across the UP.

The PAC NW ridge will have moved to the Plains for Wednesday with weak high pressure returning to the Great Lakes. This ramps up WAA for Tuesday through Thursday, bringing highs into the 50s/60s Tue/Wed with 60s/70s on Thu. Lows Mon/Tue nights will be in the 30s to low 40s, warming even further the next two nights into the 40s to low 50s. Dew points will be dry the first two days, lowering RHs back into the mid 20s to low 30s in the west. Thankfully winds don't look particularly gusty, but will continue to monitor for additional elevated fire weather conditions. Moisture advection becomes more noticeable toward the latter part of the week when the mid level ridge moves over the Great Lakes. During this period, dry weather will at least mitigate melting, but a ramp up of snowmelt is expected regardless this week given the temp forecast. This results in river flooding persisting. The mid level trough develops a surface low over the Northern Plains on Wednesday, which pivots to Manitoba for Friday, sending a warm front through on Thursday. Right now showers look unlikely (80% chance or higher for dry weather) with the warm front. Higher PoPs hold off until late Thursday night into Friday when the cold front is forced through the region. This brings back showers and thunderstorms in a similar fashion to last Friday. Generally looking at 0.25 to 0.5 inches where storms develop, but exact details on timing and amounts remain blurry. Expect cooler, but near normal temps to return post cold front into early next week.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 739 PM EDT Sun Apr 19 2026

VFR conditions expected through the TAF period as high pressure yields clearing skies across Upper Michigan tonight. W-NW winds gusting to 10-15 kt at sites this evening will become light and variable after sunset. Winds increase out of the south on Monday and gust to 20-25 kt after 18z as a system passes well to the north across Ontario.

MARINE

Issued at 328 PM EDT Sun Apr 19 2026

Northwest winds of 20-30 kts over the east half of the lake this afternoon settle below 20 kts by late tonight as high pressure moves toward Lower MI. As a result, significant wave heights relax below 4 ft over the east by mid Monday morning. This lull does not last long as south to southwest winds ramp up on Monday ahead of a cold front. Expect 15-30 kt winds lakewide with gales to 35 kts possible over the eastern third of the lake (40-50% chance). Opted to hoist a Gale Watch over the open water zones only as probabilities were highest closer to the international border.

High pressure ridging takes hold for the middle portion of the work week, settling winds once again below 20 kts through Wednesday. Southeast winds of 20-30 kts return to the east half of the lake on Thursday as a low pressure over the Northern Plains pivots to Manitoba. There is a 15-30% chance for gales to 35 kts Thursday afternoon into Friday morning ahead of a cold front. In the wake of the cold front, 20-30 kt westerly winds are expected Friday into Saturday. Expect some showers and thunderstorms Thursday night through Friday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Watch from Monday evening through late Monday night for LSZ266.

Gale Watch from Monday evening through Tuesday morning for LSZ267.

Lake Michigan... None.