979
FZUS63 KMQT 190801
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
401 AM EDT Tue Aug 19 2025

For waters beyond 5 nautical miles of shore on Lake Superior.

Waves are the significant wave height - the average of the
highest 1/3 of the wave spectrum. Occasional wave height is the
average of the highest 1/10 of the wave spectrum.

.SYNOPSIS...

Through this afternoon, 30.3 inch high pressure over QWuebec weakens
to 30.2 inches while a weak low near 30.0 inches passes over Lake
Michigan. Meanwhile a 30.1 inch high builds over southern Manitoba.
This high maintains 30.1 inches as it moves over the lake Wednesday
afternoon. By late Thursday, a 29.7 inch low over northern Manitoba
and far-northern Ontario will erode the high pressure over the Upper
Great Lakes to 30.0 inches. For Friday and into the weekend, the low
will pass along the shores of Hudson Bay at around 29.6 inches,
sending a 29.8 inch trough over Lake Superior.


LSZ162-192000-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
401 AM EDT Tue Aug 19 2025 /301 AM CDT Tue Aug 19 2025/

.EARLY THIS MORNING...West winds 5 to 15 knots. A slight chance
of showers. Waves calm to 2 feet.
.TODAY...West winds 5 to 15 knots backing southwest in the
afternoon. Waves calm to 2 feet.
.TONIGHT...Northeast winds 5 to 15 knots backing north late.
Waves calm to 2 feet.
.WEDNESDAY...Northeast winds 5 to 15 knots veering southeast
late. Waves calm to 2 feet.
.WEDNESDAY NIGHT...East winds less than 10 knots. Waves calm to
2 feet.
.THURSDAY...South winds 5 to 15 knots backing southeast by mid
afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 5 to 15 knots becoming southwest
10 to 20 knots after midnight. A chance of showers. Waves calm to
2 feet.
.FRIDAY...West winds 10 to 20 knots increasing to 15 to 25 knots.
Waves building to 2 to 4 feet.
.SATURDAY...West winds 15 to 25 knots veering northwest. Waves
building to 3 to 5 feet occasionally to 7 feet, then subsiding to
2 to 4 feet.

$$

LSZ263-192000-
Lake Superior from Saxon Harbor WI to Upper Entrance to Portage
Canal MI 5NM off shore to the US/Canadian border including Isle
Royale National Park-
401 AM EDT Tue Aug 19 2025

.EARLY THIS MORNING...South winds less than 10 knots. A slight
chance of showers. Waves calm to 2 feet.
.TODAY...Northwest winds 5 to 15 knots diminishing to less than
10 knots late. A slight chance of showers through early
afternoon. Waves calm to 2 feet.
.TONIGHT...Northeast winds less than 10 knots backing north late.
Waves calm to 2 feet.
.WEDNESDAY...Northeast winds less than 10 knots increasing to
5 to 15 knots in the afternoon. Waves calm to 2 feet.
.WEDNESDAY NIGHT...East winds less than 10 knots veering south
after midnight. Waves calm to 2 feet.
.THURSDAY...South winds 5 to 15 knots. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 5 to 15 knots becoming southwest
10 to 20 knots after midnight. A chance of showers after
midnight. Waves building to 1 to 3 feet.
.FRIDAY...Southwest winds 10 to 20 knots becoming west 15 to
25 knots. A chance of showers. Waves building to 3 to 5 feet
occasionally to 7 feet.
.SATURDAY...West winds 20 to 30 knots becoming northwest 15 to
25 knots. Waves building to 4 to 7 feet occasionally to 9 feet,
then subsiding to 3 to 5 feet occasionally to 7 feet.

$$

LSZ264-192000-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
401 AM EDT Tue Aug 19 2025

.EARLY THIS MORNING...South winds 5 to 15 knots. A slight chance
of showers. Waves 1 to 3 feet.
.TODAY...South winds 5 to 15 knots becoming north less than
10 knots in the afternoon. A slight chance of showers through
early afternoon. Waves subsiding to calm to 2 feet.
.TONIGHT...North winds less than 10 knots. Waves calm to 2 feet.
.WEDNESDAY...North winds less than 10 knots increasing to 5 to
15 knots in the afternoon, then becoming southwest less than
10 knots late. Waves calm to 2 feet.
.WEDNESDAY NIGHT...South winds less than 10 knots. Waves calm to
2 feet.
.THURSDAY...South winds 5 to 15 knots. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 5 to 15 knots becoming southwest
10 to 20 knots after midnight. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots veering west. A chance
of showers. Waves building to 2 to 4 feet.
.SATURDAY...West winds 20 to 30 knots becoming northwest 15 to
25 knots. Waves building to 4 to 7 feet occasionally to 9 feet,
then subsiding to 3 to 5 feet occasionally to 7 feet.

$$

LSZ265-192000-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
401 AM EDT Tue Aug 19 2025

.EARLY THIS MORNING...South winds 5 to 15 knots. A slight chance
of showers. Waves 1 to 3 feet subsiding to calm to 2 feet.
.TODAY...South winds 5 to 15 knots backing northeast late. A
slight chance of showers through early afternoon. Waves calm to
2 feet.
.TONIGHT...North winds 5 to 15 knots. Waves calm to 2 feet.
.WEDNESDAY...North winds 5 to 15 knots increasing to 10 to
20 knots in the afternoon, then diminishing to 5 to 15 knots
late. Waves calm to 2 feet.
.WEDNESDAY NIGHT...Southeast winds less than 10 knots veering
south after midnight. Waves calm to 2 feet.
.THURSDAY...South winds 5 to 15 knots becoming southeast 10 to
20 knots by mid afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...Southeast winds 10 to 20 knots veering
southwest after midnight. Waves calm to 2 feet.
.FRIDAY...West winds 10 to 20 knots. A chance of showers. Waves
calm to 2 feet.
.SATURDAY...West winds 20 to 30 knots becoming northwest 15 to
25 knots. Waves building to 1 to 3 feet, then subsiding to calm
to 2 feet.

$$

LSZ266-192000-
Lake Superior East of a line from Manitou Island to Marquette MI
and West of a line from Grand Marais MI to the US/Canadian Border
Beyond 5NM from shore-
401 AM EDT Tue Aug 19 2025

.EARLY THIS MORNING...Southeast winds 5 to 15 knots. A slight
chance of showers. Waves 1 to 3 feet.
.TODAY...Southeast winds 5 to 15 knots backing east late. A
slight chance of showers. Waves subsiding to calm to 2 feet.
.TONIGHT...North winds 5 to 15 knots. Waves calm to 2 feet.
.WEDNESDAY...North winds 5 to 15 knots. Waves calm to 2 feet.
.WEDNESDAY NIGHT...North winds less than 10 knots veering south
after midnight. Waves calm to 2 feet.
.THURSDAY...South winds 5 to 15 knots backing southeast by mid
afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 10 to 20 knots veering southwest
after midnight. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots veering west. A chance
of showers. Waves building to 1 to 3 feet.
.SATURDAY...West winds 15 to 25 knots veering northwest. Waves
building to 3 to 6 feet occasionally to 8 feet.

$$

LSZ267-192000-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
401 AM EDT Tue Aug 19 2025

.EARLY THIS MORNING...Southeast winds 10 to 20 knots. A chance of
showers. Waves 1 to 3 feet.
.TODAY...Southeast winds 10 to 20 knots. A slight chance of
showers. Waves subsiding to calm to 2 feet.
.TONIGHT...Southeast winds 5 to 15 knots backing east after
midnight, then backing north late. Waves calm to 2 feet.
.WEDNESDAY...North winds 5 to 15 knots increasing to 10 to
20 knots in the afternoon, then backing northwest late. Waves
calm to 2 feet.
.WEDNESDAY NIGHT...Northwest winds 5 to 15 knots veering north
after midnight. Waves calm to 2 feet.
.THURSDAY...West winds 5 to 15 knots backing east by mid
afternoon. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 5 to 15 knots increasing to 10 to
20 knots after midnight. Waves calm to 2 feet.
.FRIDAY...Southwest winds 10 to 20 knots veering west. A chance
of showers. Waves building to 1 to 3 feet.
.SATURDAY...West winds 15 to 25 knots. Waves building to 3 to
5 feet occasionally to 7 feet.

$$

LSZ261-191400-
MAFOR 1909/
Superior West 12700 13600 11800 12100. Waves 1 foot or less.

Superior North Central 11410 11300 11400 14800 11800. A chance of
showers early this morning. Waves 1 to 3 feet.

Superior South Central 11300 12400 13100 12800. Waves 1 to 3 feet
today. Waves 1 foot or less tonight.

Superior East 12320 13310 11300 12200. A chance of showers this
morning. Waves 1 to 3 feet today. Waves 2 feet or less tonight.

$$

WFO MQT

Experimental modernized open lake forecast is available online at
weather.gov/mqt/glftable

Graphical marine forecasts are available online at:
weather.gov/greatlakes