textproduct: Marquette

KEY MESSAGES

- The threat for river flooding continues over the north central and east today through the mid-week as temperatures climb into the 60s and 70s. Snowmelt continues through the week as temperatures continue rising.

- Warming temperatures and RHs in the 20 to teen percents could create limited fire weather concerns over the west and portions of the interior east today and Wednesday.

- There is over a 40% chance for low-end gales over eastern Lake Superior late Thursday through Thursday night.

DISCUSSION

Issued at 225 AM EDT Tue Apr 21 2026

While the 'dry' cold front did bring a quick-hitting swath of snow grains/sleet showers last night to the office, only a trace was seen as most of it has now either melted or evaporated as of 1 AM EDT this morning. However, with warmer air advecting into the area and dry conditions looking to still remain at the sfc, thinking the mostly sunny skies today and Wednesday will drop RHs into the 20 to teen percents over much of the interior west and some spots of the interior east during the afternoon hours today and tomorrow. With temperatures also climbing into the 60s today and into the 70s over the west half on Wednesday, some limited fire weather concerns are certainly not out of the question. However, with winds being light today into Wednesday due to weak sfc high pressure ridging moving through the area over the next 24+ hours, and with the soils still being moist from the decreasing but still ongoing snowmelt and fairly recent rainfall, thinking elevated fire weather concerns will not occur today or Wednesday. While the drier and warmer weather will help to evaporate moisture from the soil and remaining ponding water today through the middle of the week, river flooding is still looking to continue over at least the next couple of days as melting of the remaining snowpack continues over the north central and east.

The pattern begins to change by Wednesday night/Thursday as a surge of warm, moist air from the Gulf enters into Upper Michigan. While the warmest weather of this week expected to come on Thursday (highs in the 60s over the east to potentially upper 70s over the west), expect the moisture content at the sfc to also increase with the surge of this more-tropical airmass as RHs during the day only potentially drop down into the 40 to 50 percents. In addition, we may see some rain showers and thunderstorms skirt the western U.P. late Wednesday night as the surge in Gulf air could help spark warm frontogenesis over western Lake Superior. However, the chances for precipitation remain low (20% or less) late Wednesday night into Thursday as the better forcing mechanics of the warm front look to occur over far northern Minnesota and by Thunder Bay. Better chances for rainfall do look to occur Thursday night through Friday as a cold front progressively pushes from west to east across the U.P. With some of the guidance already suggesting that some initial convection that forms along the cold frontal boundary Thursday evening will potentially out-run the boundary Thursday night into Friday, expect any other convection that forms along the boundary behind this initial wave of convection to be using 'worked over' air. Thus, while there may be a non-zero chance for a stronger thunderstorm or two near Ironwood Thursday evening, thinking severe weather chances will be next to zero Thursday night through Friday everywhere else, with only heavy downpours in the strongest showers and thunderstorms being the biggest impact.

Behind the cold front, expect temperatures that are more normal for late April to come into Upper Michigan (highs in the 50s to maybe low 60s and lows in the 30s). Some drier air seen immediately behind the cold front could bring RHs back down to 30% or less on Saturday (up to a 30% chance according to the LREF). However, with a deepening low pressure system looking to lift towards the Upper Midwest near the end of the forecast period, more moist if not rainy conditions may return by the middle of next week.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 653 AM EDT Tue Apr 21 2026

Weak high pressure ridging brings VFR conditions and light winds to the area today and tonight.

MARINE

Issued at 225 AM EDT Tue Apr 21 2026

As the cold front finishes pushing through Lake Superior this morning, expect the winds to drop down to 20 knots or less after sunrise. With weak high pressure ridging moving over the area the next 24+ hours, expect the light winds to remain over the lake until Wednesday night, when a surge of air from the Gulf increases winds from the southeast to 20 to 25 knots over the north central and eastern lake late during the overnight hours. The winds continue to build from the southeast Thursday into Thursday night as a cold front approaches from the west. Eventually, southwest gales up to 35 knots could start to occur Thursday evening over the eastern open lake, with chances for low-end gales becoming maximized to over 40% late Thursday night. While some rain showers are expected along and ahead of the cold front's passage Thursday night through Friday, no severe weather is really expected save for maybe a low-end chance for some stronger storms closer to Duluth early Thursday evening.

Behind the cold front, expect the winds to become westerly gusting up to 20 to 25 knots Friday night into early Saturday. After that, expect light winds of 20 knots or less to return to Lake Superior for the rest of the weekend thanks to a weak pressure gradient and high pressure ridging.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... None. Lake Michigan... None.