textproduct: Marquette

KEY MESSAGES

- Another warm and pleasant fall day with temperatures in the low to mid 70s this afternoon.

- Rain chances return to the area tonight through Thursday, with the best chances over the southcentral and eastern UP.

- Marginal (~35 knot) west-northwest gales are possible (25-35% chance) along the southern Lake Superior shoreline from the Keweenaw to Whitefish Point on Thursday. Expect breezy conditions over adjacent land areas.

DISCUSSION

Issued at 352 AM EDT Tue Sep 29 2026

Early morning RAP analysis shows surface high pressure lingering over the eastern half of Lake Superior, supporting areas of locally dense fog over the lake and adjacent parts of the eastern UP, mainly from Luce County eastward. Clear skies have allowed temperatures drop into the 40s across the central UP, with a few of the colder spots getting into the upper 30s. Temperatures are holding in the 50s in the west as insulating high cloud cover begins to stream over the region ahead more unsettled weather beginning to take shape over the northern Plains.

RAP analysis and water vapor imagery reveal a split flow pattern across the western half of North America, with one shortwave trough emerging form the Canadian Rockies while a cutoff low spins over the Desert Southwest. Deep southwest flow is becoming established across the central CONUS ahead of this large scale troughing, with a plume of rich moisture characterized by 1.5+ inch PWAT values taking aim on the northern Mississippi River Valley and eventually the Upper Great Lakes. In the meantime, expect another pleasant day across Upper Michigan today as morning fog eventually dissipates and gives way to temperatures in the low to mid 70s amidst southerly low level flow. Could see a few showers develop across the far western UP by later this afternoon into this evening as a weak disturbance grazes the western half of Lake Superior ahead of the trough moving out of western Canada, with rain chances spreading east across the rest of the UP tonight.

Latest guidance continues to trend more pessimistic with regard to rain chances across the UP from Wednesday into Thursday as the northern and southern stream energy remain out of phase and leave the UP stuck in the middle between systems. The western Canada trough eventually spawns a deep surface low that will track well north of the area into Hudson Bay on Wednesday. Meanwhile, another low will develop over the South Plains and lift northeast towards the Great Lakes through Thursday, but the bulk of the guidance keeps this feature well south of the area, with the southcentral and eastern UP seeing the best chances for meaningful rainfall out of this system. As such, NBM probs for a wetting rain of a quarter inch have dwindled to around 25% across the northern tier of the UP through midweek, while the southcentral UP remains around 75% or higher. Still, chances for more significant rainfall have come down across southcentral, with probs for as much as a half inch now under 50%.

Cooler west-northwest flow will bring breezy conditions on Thursday as near gales on Lake Superior could translate to winds gusting to 35-40 mph in the Keweenaw and 30+ mph east along the shoreline. Additionally increasing Delta Ts as 850 mb temps plummet to around 0 C while lake surface temps remain around 13-16 C could result in lake induced rain showers or drizzle along the higher terrain of the north central UP on Thursday. More tranquil weather returns late in the week as high pressure builds over the northern Plains and shifts eastward, bringing seasonable temps in the low to mid 60s. Will have to keep an eye on frost concerns from Thursday night onward. Another system looks to bring additional rain chances later in the weekend.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 727 AM EDT Tue Sep 29 2026

Fog has lifted at from CMX this morning resulting in VFR conditions at all sites. These conditions should persist through much of the afternoon. A shortwave brings in a round of light rain showers from the west this evening, yielding periods of MVFR CIGs/VIS before widespread CIGs lower to IFR late. Otherwise winds remain light through mid morning, mainly 5 kts or less, increasing out of the south to between 10-15 kts with gusts around 20 kts by this afternoon.

MARINE

Issued at 352 AM EDT Tue Sep 29 2026

Lake Superior: Southerly winds increase to 20-25 kt this afternoon as a disturbance skirts our area to the northwest this evening into tonight. A few gusts up to 30 kts are possible over the eastern lake late in the day as a LLJ moves into the area. Small craft headlines have been hoisted for some of the central/eastern nearshores this afternoon. Winds do generally slacken to 20 kts or less by Wednesday behind the shortwave, but the eastern open lake may hang on to southerly 20 to 25 kt winds until Wednesday evening. As CAA moves into the area early Thursday through the rest of the day, expect winds to pickup from the west-northwest to 20 to 30 kts across the lake, with gales up to 35 kts possible along the southern shoreline from the Keweenaw to Whitefish Point (the current NBM has gales at ~35 kts or higher at 25 to 35% along the aforementioned area for Thursday). As ridging builds back in late this week, expect the winds to die down to 20 kts or less again by Thursday night/Friday morning and to remain that way through Saturday.

Northern Green Bay and northwestern Lake Michigan: Expect winds to pick up from the south and southwest to 15 to 20 kts today as a shortwave passes north op the area from the northern Plains to Hudson Bay. The winds may increase to 20 to 30 kts by early Wednesday as a low over the Southern Plains dissipates and heads towards the Mid-Atlantic/New England. However, once it passes expect the winds to quickly diminish to 15 kts or less Wednesday night/Thursday morning before picking back up to 15 to 20 kts from the northwest on Thursday via CAA. Expect the winds to slacken to 15 kts or less again by Thursday night and to remain light the rest of this week as ridging returns to the area.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Dense Fog Advisory until 8 AM EDT this morning for LSZ250-251- 266-267.

Lake Michigan... None.