textproduct: Marquette

KEY MESSAGES

- Widespread rain showers move into the UP from west to east tonight through Tuesday morning. There is a general 25-75% chance for rainfall amounts >0.5", with the highest chances across the southern half of the UP.

- A Wind Advisory has been issued for Northern Houghton and Keweenaw Counties on Tuesday. Strong westerly winds with frequent gusts of 45+ mph are likely (60-90% chance).

- Gale Warnings remain in effect for the Upper Great Lakes tonight through Tuesday. Southerly gales 35-40 kts turn westerly by early Tuesday afternoon. Westerly gusts 40-45 kts will be common with a few Storm force gusts to 50 kts possible (up to 50% chance) near the Keweenaw Peninsula.

- Strong winds over the Upper Great Lakes tonight through Tuesday are expected to create dangerous swimming conditions along the Schoolcraft and Alger County shorelines on Tuesday.

DISCUSSION

Issued at 250 PM EDT Mon Sep 14 2026

Afternoon GOES water vapor imagery reveals a sharp trough digging across eastern Montana that is supporting a ~998 mb surface low along the Canada/MT/ND border. A strong 45-60 kt 850 mb jet stretches from northern MO all the way to southern Manitoba, transporting warm moisture air northward and isentropically forcing an area of showers and thunderstorms from Iowa through Minnesota. Closer to home, departing high pressure has kept the UP dry thus far. This region of precipitation is slated to lift from west to east across the UP this evening through Tuesday morning as the trough and surface low work northward through northern Ontario. CAM ensembles largely agree upon the southern half of the UP receiving a health 0.25-0.75" of rain, with the greatest probability for >0.5" concentrated in Menominee and Delta counties (60-90% chance). Elsewhere, 0.25-0.50" is expected. Apart from the rain, gusty winds are the other main concern of the short term forecast period. Southerly wind gusts 25-35 mph will be common tonight with potentially stronger gusts near 40 mph in the downsloping areas of the central UP. Tomorrow, the attendant surface low pressure system cold front will press through the region during the late morning to early afternoon hours, veering winds to the west. Strong pressure rises upwards of 1-2 mb/hour and modest upper level cold air advection will work to increase wind gusts on Lake Superior and in the Keweenaw between 40-50 mph with occasional gusts to 55 mph should mixing be able to tap into higher gusts aloft. A Windy Advisory has been issued for N Houghton and Keweenaw Counties from 15-00z Tuesday (10a-8p local).

Moving into the rest of the week, expect generally quieter weather as zonal flow in the upper levels and shortwave ridges moving through the U.P. generally keep active weather away. While this should keep temperatures fairly seasonable for the rest of the week, this does also support dry weather continuing until the end of the forecast period, provided we don't get grazed by a nearby shortwave.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 834 PM EDT Mon Sep 14 2026

Flight conditions will deteriorate to MVFR with periods of IFR through this evening as rain spreads into the UP ahead of an incoming frontal system along with gusty southerly winds. A 50 kt LLJ moving into the region will also bring low level wind shear concerns to all terminals through 06-08z tonight. Rain departs to the east Tuesday morning, yielding a gradual improving trend back to VFR. Winds will shift westerly behind a trailing cold front and continue to gust to 25-30 kt into the afternoon, perhaps as high as 40-45 kt at KCMX.

MARINE

Issued at 250 PM EDT Mon Sep 14 2026

Lake Superior: Increasing southerly winds are being observed this afternoon as a deepening surface low continues northeast towards northern Ontario and surface high pressure departs the Great Lakes. This evening and into the overnight hours, southerly gusts 35-40 kts will be common in the eastern half of the lake. By the late morning to early afternoon, the system's cold front will traverse the lake, veering winds to the west. Given strong pressure rises and increase cold air advection, westerly winds are expected to increase between 35-45 kts for much of the lake. There is a 50-60% chance for a few Storm force gusts to 50 kts around the Keweenaw. Have maintained Gale Warnings for dual directional gales tonight through tomorrow evening. Westerlies fall below 35 kts tomorrow evening and continue diminishing overnight through Wednesday.

Northern Green Bay and northwestern Lake Michigan: Southerly winds are on the rise this afternoon eventually reaching gales to 35 kts by around midnight tonight. As winds turn westerly behind a cold front Tuesday morning/early afternoon, winds fall below 25 kts and continue diminishing to 15 kts or less through the evening.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Wind Advisory from 11 AM to 8 PM EDT Tuesday for MIZ001-003.

Lake Superior... Gale Warning until 8 AM EDT Tuesday for LSZ249.

Gale Warning from 8 AM EDT /7 AM CDT/ to 4 PM EDT /3 PM CDT/ Tuesday for LSZ162.

Gale Warning from 8 AM EDT /7 AM CDT/ to 5 PM EDT /4 PM CDT/ Tuesday for LSZ240.

Gale Warning from 8 AM EDT /7 AM CDT/ to 8 PM EDT /7 PM CDT/ Tuesday for LSZ241>243-263-264.

Gale Warning until 8 PM EDT Tuesday for LSZ244-245-248-265-266.

Gale Warning from 10 AM to 8 PM EDT Tuesday for LSZ246-247.

Gale Warning from 2 AM to 8 PM EDT Tuesday for LSZ250.

Gale Warning from 3 AM to 9 AM EDT Tuesday for LSZ251-267.

Lake Michigan... Gale Warning until 8 AM EDT Tuesday for LMZ221-248-250.