textproduct: Marquette

KEY MESSAGES

- A Dense Fog Advisory remains in effect through 10 am EDT Thursday for the MQT County Warning Area.

- The threat for flooding continues due to snowmelt. A Flood Watch is in effect for everywhere except the far western UP through tonight.

- Showers and thunderstorms are expected with a cold front Friday evening into Saturday early morning. Widespread totals of 0.25 to 0.75 inches are expected, with up to 30% probability of exceeding an inch, best chances over the south half.

- Some stronger storms capable of producing hail and strong wind gusts are possible Friday night.

- Becoming much cooler this weekend, which will slow snowmelt.

DISCUSSION

Issued at 243 AM EDT Thu Apr 16 2026

Early morning RAP analysis reveals anomalous midlevel ridging over the eastern third of the CONUS and a deep, compact trough over the Pacific Northwest. Between these features, a compact shortwave trough is rippling through MN and WI. At lower levels, a broad surface low is tracking into southern WI with a diffuse frontal boundary extending northeast of it into the central LP. Convection along this boundary has remained well to our south, but as the surface low continues to make its way into Lower Michigan through the early morning hours, it is not out of the question for us to get grazed by some light rain. Otherwise, the main concern for tonight remains our potential for dense fog. Nighttime microphysics shows plenty of either fog or low stratus across the central and eastern UP - and ground truth is starting to catch up with ASOS sites starting to drop across the eastern 2/3 of the UP. While the western UP has yet to see any fog development, clear skies, light winds, and saturated lower levels spells out a good potential for this to develop there as well. A Dense Fog Advisory will remain in effect through this morning across the entire UP.

Shortwave ridging over the area today will allow for a quiet day with clearing skies across most of the area soon after sunrise. That said, onshore flow over the north-central and eastern UP should keep in cloud cover for longer there. As the airmass remains anomalously warm (850 mb temps around 10C or +1 to +2 sigma), unseasonable warmth will occur where clouds clear and deeper mixing happens, with a high chance of temps in the 70s and a low chance of approaching 80 in some spots in the interior-western UP. Meanwhile in the east, clouds hanging on longer and potential for onshore flow will keep things significantly cooler, with areas along the lakeshore likely remaining below 50F.

Friday, ridging builds ahead of the Pac NW trough shifting across the northern Plains. A strong capping inversion should keep things dry until the front arrives and crosses the UP from west to east roughly 00-06Z Sat. Another very warm day is expected in the west half, while it will be a bit cooler with flow off Lake Michigan in the east half. GFS/NAM indicate elevated instability approaching 1000 J/kg with strong deep layer shear, so a few stronger storms resulting in hail and gusty winds cannot be ruled out. Anomalous moisture with PWATs of 1-1.25 inches will be in place, but the quick movement of the trough is expected to limit QPF to 0.25-0.75" in most areas. However, potential for a wave to develop along the front would prolong rainfall a bit, which could result in higher precip amounts (20-30% chance of exceeding an inch in southern locations).

A sharply colder airmass will move in for the weekend with temperatures back below normal. Lingering precipitation into Saturday morning changes over to snow, though impactful accumulations are not expected. By Saturday evening, temperatures aloft turn cool enough that we may just be able to pick up on some lake effect snow (note in soundings a steepening inversion height and a saturated DGZ). However, dry air above and below the DGZ prove a limiting factor in snowfall amounts, which remain well below an inch Saturday night. Temperatures begin to trend warmer again into next week, with a mainly dry period ahead courtesy of ridging over the region.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 129 AM EDT Thu Apr 16 2026

Warm and moist southerly flow accompanied by the snowmelt is supplying ample low level moisture. Low stratus and fog noted by regional satellite is only lowering viz at CMX as of 06z, but could plague IWD/SAW (moreso SAW) through the early morning. As has been seen the last few nights, any fog/stratus will lift to MVFR/VFR through the late morning to early afternoon. Light winds <15 kts are expected through the TAF period.

MARINE

Issued at 243 AM EDT Thu Apr 16 2026

Light, stable flow is expected through Thursday with a weak pressure gradient over the area. Areas of dense fog are expected through at least this evening.

Southerly winds will develop and increase on Friday ahead of a deepening low pressure, with a 30-50% chance for brief gales over the eastern lake Friday evening. With stable southerly flow, the highest winds will be observed on high observing platforms. This low will push through over the weekend bringing a cold front and the potential for northwesterly gales (around 50% chance Saturday into Sunday). NW winds slowly decrease throughout the day Sunday, then winds across the entirety of the lake will briefly be below 20kts early Monday while shifting over to the south. Winds become elevated again Monday evening through Tuesday as low pressure moves through Ontario.

HYDROLOGY

Issued at 350 PM EDT Wed Apr 15 2026

NOHRSC analysis showed the the snowpack had eroded over much of the southern and far western U.P. Over the north and east several inches to over a foot of SWE remained, greatest in the higher terrain. Snowmelt will continue through the week and accelerate late in the week as a warm, moist airmass moves into the U.P. An area of showers and thunderstorms will move through late Friday into Friday night with 0.25-0.75 inches expected for most areas, and a 20-30% of exceeding an inch in the southern UP. Colder weather is expected for Saturday night and Sunday which should slow the melt of any remaining snow.

Waters remain high in the southern UP where recent heavy rains and snowmelt contributed to flooding of low-lying areas and some rivers. Rivers will continue to rise in portions of the northern UP due to continued snowmelt and additional rainfall. A Flood Watch remains in effect through Thursday night for all but the far western UP, and may be extended through Friday night.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Flood Watch through late tonight for MIZ001-003>007-010>014- 084-085.

Dense Fog Advisory until 10 AM EDT /9 AM CDT/ this morning for MIZ001>007-009>014-084-085.

Lake Superior... Dense Fog Advisory until 11 AM EDT /10 AM CDT/ this morning for LSZ162-240>251-263>267.

Lake Michigan... Dense Fog Advisory until 11 AM EDT this morning for LMZ221-248- 250.