textproduct: Marquette

KEY MESSAGES

- Patchy dense fog is possible (20-40% chance) this morning.

- Widespread rain chances return Monday night.

UPDATE

Issued at 231 AM EDT Sat Apr 25 2026

Going forecast remains on track with GOES-East Nighttime Microphysics RGB imagery showing the front that brought precip to the UP yesterday completely into Ontario with low clouds over the eastern 2/3 of Lake Superior and UP. It is a little tricky to say whether these are just low stratus or fog, as METARs at SAW and CMX say it's low stratus (10SM and OVC005) but IWD and ERY on opposite sides of the UP are reporting 2SM and 1 1/2SM respectively. Given the spatial inconsistency of fog, a Dense Fog Advisory is unlikely, but if ceilings further descend, a reactive SPS may be issued.

Otherwise, the highest impact weather in the short term will be the RHs today. NBM RHs only fall to the mid-30s percent range in the interior west today. While soundings show copious amounts of dry air in the lowest 5kft, the flow is also stagnant, with 6 kt or less winds in the bottom 4kft, reducing the efficiency of boundary layer mixing. Additionally, high clouds streaming in from the west are also expected to create partly to mostly cloudy skies, inhibiting surface heating some and making mixing less efficient. Regardless, fire weather concerns are low because that same stagnant flow will keep surface gusts across much of the UP at 10 kt or less.

Otherwise, mostly benign weather follows for Sunday, and the most recent suite of global ensembles does not provide enough increased certainty with the approaching Colorado Low to deviate from the going forecast for the next week.

DISCUSSION

Issued at 306 PM EDT Fri Apr 24 2026 Amended at 231 AM EDT Sat Apr 25 2026

Given cool northerly flow and decreasing winds, expecting low temps to fall into the 30s and low 40s this morning. Lingering low level moisture may allow the development for patchy fog tonight, though confidence is low regarding the spatial extent and persistent through sunrise.

Heading into the rest of the weekend, local ridging and height rises keep things warm and dry with daytime highs warming into the 50s (40s lakeshores) tomorrow and 60s (50s lakeshores) Sunday. Bufkit soundings show modest inverted-v profiles across the interior west both tomorrow and Sunday afternoon, suggesting efficient drying taking place. Medium range ensembles paint a 30-60% chance for RHs falling below 35% closer to the WI/UP stateline. Forecaster uncertainty regarding how low RHs fall remains somewhat high considering recent wetting rain, however, recent dry days have certainly ended up drier than expected. So if enough sunshine is present and temps soar greater than the NBM suggests, more widespread RHs 25-35% are not out of the question. That said, there are little to no fire weather concerns at the moment as winds are expected to be on the lighter side, mixing 10-15 kts each afternoon.

Medium and long range guidance is in good agreement that a more substantial shortwave will emerge out of the southern Rockies Monday, lifting through the Plains and Mid-Mississippi Valley into the northern Great Lakes by Monday night. Ample moisture (PWATs in the 97.5th percentile of NAEFS climo) and isentropic ascent in the warm sector of a deepening sfc low will result in widespread precipitation overnight through Tuesday afternoon. Latest ensembles suggest a 40-60% chance for rainfall >0.5" across the west half of the UP, especially closer to the stateline. At this time, confidence is low regarding the northward extent of elevated instability and embedded thunderstorm potential. Interested parties should remain in tune with future forecast packages as flooding concerns surrounding high rivers are expected to continue.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 723 AM EDT Sat Apr 25 2026

Low stratus is bringing LIFR conditions to CMX and SAW this morning, with IWD forecast to remain outside of the low stratus today. While the general trend will be lifting ceilings at CMX/SAW, it could take until the early afternoon, with the recent LAMP guidance suggesting 40% chances of IFR ceilings lingering at SAW until as late as 19Z. Tonight will be similar to last night, where light winds and moist air near the surface will provide some potential for FG formation. Current probabilities of FG at IWD by 12Z are around 30%, with around 40% probabilities of +FG at CMX and SAW. Will include some vis reduction at CMX/SAW and leave it out of IWD for now, but uncertainty is high.

MARINE

Issued at 306 PM EDT Fri Apr 24 2026 Amended at 231 AM EDT Sat Apr 25 2026

West to northwest winds diminish below 15 kts lakewide this morning, lasting through the rest of the weekend thanks to a weak pressure gradient and high pressure ridging. A more substantial low pressure system is slated to lift into the northern Great Lakes Monday night resulting in two periods of gales through Tuesday. The first period starts Monday night with strong southerly to southeasterly winds in the warm sector of the surface low. The second period comes behind the cold front as strong cold air advection and modest pressure rises result in westerly gales Tuesday afternoon. At this time, NBM probabilities for gales only peak at 50% for both periods, but given the pressure gradient seen in deterministic solutions, I believe those probabilities to be on the low end. The Euro ENS suggests chance for gusts >35 kts in the 70-90% range, which matches pattern recognition a bit better. More details will come with future forecast packages.

MQT WATCHES/WARNINGS/ADVISORIES

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