705
FZUS63 KMQT 222002
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
401 PM EDT Fri Aug 22 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...

As Hurricane Erin shifts north and east away from the East Coast
this afternoon and evening, high pressure at now 30.0 inches over
the southern Great Lakes is moving over to the East Coast while a
29.7 inch low over northern Ontario deepens to 29.5 inches and lifts
toward James Bay Saturday. This allows troughing over Lake Superior
to strengthen to 29.7 inches tonight before weakening Saturday. The
parent low then slowly weakens to 29.6 inches Sunday and Monday as
it moves into northern Quebec. As this happens, 30.2 inch high
pressure stretches over the Great Plains early next week, eventually
bringing ridging of at least 30.1 inches back over the western
portions of Lake Superior Monday and Tuesday. High pressure of 30.2
inches remains over the Lower Midwest Wednesday, though a 29.9 inch
trough is projected to pass over Lake Superior in association with a
29.7 inch shortwave racing through far northern Ontario.


LSZ162-230800-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
401 PM EDT Fri Aug 22 2025 /301 PM CDT Fri Aug 22 2025/

.LATE THIS AFTERNOON...Southwest winds 10 to 20 knots. A slight
chance of showers and thunderstorms. Waves calm to 2 feet.
.TONIGHT...Southwest winds 10 to 20 knots veering west after
midnight, then increasing to 15 to 25 knots late. A slight chance
of showers and thunderstorms through midnight. Waves building to
3 to 5 feet occasionally to 7 feet.
.SATURDAY...West winds 20 to 30 knots diminishing to 15 to
25 knots late. Waves subsiding to 2 to 4 feet.
.SATURDAY NIGHT...West winds 20 to 30 knots veering northwest
late. A slight chance of showers after midnight. Waves 2 to
4 feet.
.SUNDAY...Northwest winds 20 to 30 knots. A slight chance of
showers. Waves building to 3 to 5 feet occasionally to 7 feet,
then subsiding to 2 to 4 feet.
.SUNDAY NIGHT...Northwest winds 15 to 25 knots. Waves 2 to
4 feet.
.MONDAY...Northwest winds 10 to 20 knots. Waves subsiding to calm
to 2 feet.
.MONDAY NIGHT...Northwest winds 10 to 20 knots diminishing to
5 to 15 knots after midnight. Waves calm to 2 feet.
.TUESDAY...Southwest winds 10 to 20 knots veering west. Waves
calm to 2 feet.
.WEDNESDAY...Southwest winds 10 to 20 knots. Waves building to
1 to 3 feet, then subsiding to calm to 2 feet.

$$

LSZ263-230800-
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 PM EDT Fri Aug 22 2025

.LATE THIS AFTERNOON...Southwest winds 5 to 15 knots. A chance of
showers and thunderstorms. Waves calm to 2 feet.
.TONIGHT...Southwest winds 5 to 15 knots becoming west 10 to
20 knots after midnight, then increasing to 15 to 25 knots late.
A slight chance of showers and thunderstorms. Waves building to
3 to 5 feet occasionally to 7 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon. Waves building to 3 to 6 feet
occasionally to 8 feet.
.SATURDAY NIGHT...West winds 20 to 30 knots diminishing to 15 to
25 knots after midnight, then veering northwest late. A slight
chance of showers and thunderstorms. Waves subsiding to 3 to
6 feet occasionally to 8 feet.
.SUNDAY...Northwest winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. A chance of showers and a slight
chance of thunderstorms. Waves 3 to 6 feet occasionally to
8 feet.
.SUNDAY NIGHT...Northwest winds 20 to 30 knots diminishing to
15 to 25 knots after midnight. Waves 3 to 6 feet occasionally to
8 feet.
.MONDAY...Northwest winds 15 to 25 knots diminishing to 10 to
20 knots by mid afternoon. Waves subsiding to 1 to 3 feet.
.MONDAY NIGHT...Northwest winds 5 to 15 knots. Waves subsiding to
calm to 2 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
calm to 2 feet.
.WEDNESDAY...Southwest winds 15 to 25 knots diminishing to 10 to
20 knots. Waves building to 2 to 4 feet, then subsiding to 1 to
3 feet.

$$

LSZ264-230800-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
401 PM EDT Fri Aug 22 2025

.LATE THIS AFTERNOON...Southwest winds 5 to 15 knots. A slight
chance of showers and thunderstorms. Waves calm to 2 feet.
.TONIGHT...Southwest winds 5 to 15 knots becoming west 15 to
25 knots late. A slight chance of showers and thunderstorms.
Waves building to 2 to 4 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon. Waves building to 3 to 6 feet
occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots veering northwest
after midnight. A slight chance of showers and thunderstorms
after midnight. Waves subsiding to 3 to 5 feet occasionally to
7 feet.
.SUNDAY...Northwest winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. A slight chance of showers. Waves 3 to
5 feet occasionally to 7 feet.
.SUNDAY NIGHT...Northwest winds 15 to 25 knots. Waves building to
3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 15 to 25 knots veering north by mid
afternoon. Waves subsiding to 2 to 4 feet.
.MONDAY NIGHT...Northwest winds 15 to 25 knots diminishing to
10 to 20 knots after midnight. Waves subsiding to calm to 2 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
calm to 2 feet.
.WEDNESDAY...West winds 10 to 20 knots. Waves building to 1 to
3 feet.

$$

LSZ265-230800-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
401 PM EDT Fri Aug 22 2025

.LATE THIS AFTERNOON...West winds 5 to 15 knots. Showers likely
and a chance of thunderstorms. Waves calm to 2 feet.
.TONIGHT...Southwest winds 10 to 20 knots veering west late. A
chance of showers and thunderstorms. Waves building to 1 to
3 feet.
.SATURDAY...West winds 20 to 30 knots. Waves building to 3 to
5 feet occasionally to 7 feet.
.SATURDAY NIGHT...West winds 20 to 30 knots diminishing to 15 to
25 knots after midnight. A chance of showers. A slight chance of
thunderstorms after midnight. Waves subsiding to 1 to 3 feet.
.SUNDAY...West winds 15 to 25 knots becoming northwest 20 to
30 knots by mid afternoon. A chance of showers and a slight
chance of thunderstorms. Waves building to 3 to 5 feet
occasionally to 7 feet.
.SUNDAY NIGHT...Northwest winds 20 to 30 knots. A chance of
showers. Waves subsiding to 2 to 4 feet, then building to 3 to
5 feet occasionally to 7 feet.
.MONDAY...Northwest winds 20 to 30 knots. Waves building to 3 to
6 feet occasionally to 8 feet.
.MONDAY NIGHT...Northwest winds 10 to 20 knots. Waves subsiding
to 1 to 3 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to calm to 2 feet.
.WEDNESDAY...West winds 10 to 20 knots. Waves calm to 2 feet.

$$

LSZ266-230800-
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 PM EDT Fri Aug 22 2025

.LATE THIS AFTERNOON...West winds 5 to 15 knots. A chance of
showers and thunderstorms. Waves calm to 2 feet.
.TONIGHT...Southwest winds 10 to 20 knots. A chance of showers
and thunderstorms. Waves building to 1 to 3 feet.
.SATURDAY...West winds 15 to 25 knots increasing to 20 to
30 knots in the afternoon. Waves building to 3 to 6 feet
occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. A chance of showers.
A slight chance of thunderstorms after midnight. Waves subsiding
to 2 to 4 feet.
.SUNDAY...Northwest winds 15 to 25 knots increasing to 20 to
30 knots by mid afternoon. A chance of showers and a slight
chance of thunderstorms. Waves building to 3 to 6 feet
occasionally to 8 feet.
.SUNDAY NIGHT...Northwest winds 20 to 30 knots. A chance of
showers. Waves building to 4 to 7 feet occasionally to 9 feet,
then subsiding to 3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 20 to 30 knots. Waves building to 4 to
8 feet occasionally to 10 feet.
.MONDAY NIGHT...North winds 15 to 25 knots backing northwest
after midnight. Waves subsiding to 2 to 4 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to calm to 2 feet.
.WEDNESDAY...West winds 10 to 20 knots diminishing to 5 to
15 knots. Waves building to 1 to 3 feet.

$$

LSZ267-230800-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
401 PM EDT Fri Aug 22 2025

.LATE THIS AFTERNOON...Southwest winds 5 to 15 knots. A chance of
showers and thunderstorms. Waves calm to 2 feet.
.TONIGHT...Southwest winds 10 to 20 knots. Showers through
midnight. A chance of thunderstorms. A chance of showers after
midnight. Waves calm to 2 feet.
.SATURDAY...West winds 10 to 20 knots increasing to 15 to
25 knots in the afternoon. A slight chance of showers and
thunderstorms through early afternoon. Waves building to 3 to
6 feet occasionally to 8 feet.
.SATURDAY NIGHT...West winds 15 to 25 knots. A slight chance of
showers after midnight. Waves subsiding to 3 to 5 feet
occasionally to 7 feet.
.SUNDAY...West winds 15 to 25 knots increasing to 20 to 30 knots
by mid afternoon. A chance of showers and a slight chance of
thunderstorms. Waves subsiding to 2 to 4 feet, then building to
3 to 6 feet occasionally to 8 feet.
.SUNDAY NIGHT...Northwest winds 20 to 30 knots. A chance of
showers. Waves building to 4 to 7 feet occasionally to 9 feet,
then subsiding to 3 to 6 feet occasionally to 8 feet.
.MONDAY...Northwest winds 20 to 30 knots. Waves building to 4 to
8 feet occasionally to 10 feet.
.MONDAY NIGHT...North winds 15 to 25 knots backing northwest
after midnight. Waves subsiding to 2 to 4 feet.
.TUESDAY...Northwest winds 10 to 20 knots backing west. Waves
subsiding to 1 to 3 feet.
.WEDNESDAY...West winds 10 to 20 knots. Waves subsiding to calm
to 2 feet.

$$

LSZ261-230200-
MAFOR 2221/
Superior West 12510 11620 14630 11630. Waves 1 to 3 feet building
to 2 to 4 feet tonight. Waves 3 to 5 feet Saturday.

Superior North Central 13510 11520 11620 12630 11640. A chance of
showers this evening. Waves 1 to 3 feet tonight. Waves 2 to 4
feet building to 3 to 5 feet Saturday.

Superior South Central 11516 11506 12510 13630 11640. A chance of
thunderstorms this evening. Waves 2 feet or less tonight. Waves 2
to 4 feet building to 3 to 5 feet Saturday.

Superior East 11500 11516 11506 12510 11620 12630. A chance of
thunderstorms tonight. Waves 1 to 2 feet tonight. Waves 1 to 3
feet building to 3 to 6 feet Saturday.

$$

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