259
FZUS63 KMQT 182006
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
406 PM EDT Wed Sep 18 2024

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...A 30.1 inch high pressure ridge extending from the
Saint Lawrence Valley back into the Great Lakes region tonight
reorients from Quebec into the Great Lakes region Thursday.
Meanwhile, a 29.3 inch low pressure over the east half of Montana
tonight spins into southern Manitoba Thursday with its associated
29.6 inch trough sweeping east into western Minnesota. As the low
continues to track northeast to Hudson Bay Friday, the associated
trough will fill to 29.8 inches as it approaches western Lake
Superior. This trough will then dissipate, allowing weak 29.9 inch
ridging to anchor over the Upper Great Lakes Saturday morning. A new
low pressure of 29.7 inches over southern Manitoba Saturday morning
will then track into far northern Ontario Saturday night with its
associated 29.9 inch trough sweeping across Lake Superior. In its
wake, 30.2 inch high pressure build into Ontario Sunday. A 29.7 in
low moves into the Upper Great Lakes on Sunday afternoon deepening
to 29.6 inches over Lake Superior on early Monday morning. High
pressure at 30.0 inches over the northern Plains clips western Lake
Superior by Monday afternoon.

LSZ162-190415-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
406 PM EDT Wed Sep 18 2024 /306 PM CDT Wed Sep 18 2024/

.LATE THIS AFTERNOON...East winds 10 to 20 knots. Waves calm to
2 feet.
.TONIGHT...Southeast winds 10 to 20 knots becoming south 5 to
15 knots after midnight, then becoming southeast 10 to 20 knots
late. A slight chance of showers and thunderstorms after
midnight. Waves calm to 2 feet.
.THURSDAY...East winds 10 to 20 knots veering southeast in the
afternoon, then backing east late. A chance of showers and
thunderstorms. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 10 to 20 knots veering southwest
late. A chance of showers and thunderstorms. Waves building to
1 to 3 feet.
.FRIDAY...Southwest winds 10 to 20 knots. Waves subsiding to calm
to 2 feet.
.FRIDAY NIGHT...West winds 5 to 15 knots. Waves calm to 2 feet.
.SATURDAY...Southwest winds 5 to 15 knots becoming south 10 to
20 knots by mid afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...North winds 10 to 20 knots. A chance of
showers. Waves calm to 2 feet.
.SUNDAY...Northwest winds 10 to 20 knots veering north. A chance
of showers. Waves calm to 2 feet.
.MONDAY...Northeast winds 10 to 20 knots veering east. A chance
of showers. Waves building to 2 to 4 feet, then subsiding to 1 to
3 feet.

$$

LSZ263-190415-
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-
406 PM EDT Wed Sep 18 2024

.LATE THIS AFTERNOON...Southeast winds 5 to 15 knots. Waves calm
to 2 feet.
.TONIGHT...Southeast winds 5 to 15 knots veering south after
midnight. Waves calm to 2 feet.
.THURSDAY...South winds 10 to 20 knots backing southeast in the
afternoon. A slight chance of showers. A slight chance of
thunderstorms by mid afternoon. Waves building to 1 to 3 feet.
.THURSDAY NIGHT...South winds 10 to 20 knots. A chance of showers
and thunderstorms. Waves building to 2 to 4 feet, then subsiding
to 1 to 3 feet.
.FRIDAY...Southwest winds 10 to 20 knots. A slight chance of
showers and thunderstorms through early afternoon. Waves
subsiding to calm to 2 feet.
.FRIDAY NIGHT...Southwest winds 5 to 15 knots becoming west less
than 10 knots after midnight. Waves calm to 2 feet.
.SATURDAY...Southwest winds 5 to 15 knots backing south by mid
afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...South winds 5 to 15 knots backing north after
midnight. A chance of showers. Waves calm to 2 feet.
.SUNDAY...Northwest winds 10 to 20 knots veering north. A chance
of showers. Waves calm to 2 feet.
.MONDAY...Northeast winds 10 to 20 knots veering east. A chance
of showers. Waves building to 1 to 3 feet.

$$

LSZ264-190415-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
406 PM EDT Wed Sep 18 2024

.LATE THIS AFTERNOON...Southeast winds 5 to 15 knots. Waves 1 to
3 feet.
.TONIGHT...Southeast winds 10 to 20 knots veering south after
midnight, then diminishing to 5 to 15 knots late. Waves 1 to
3 feet.
.THURSDAY...South winds 10 to 20 knots backing southeast in the
afternoon. A slight chance of showers and thunderstorms by mid
afternoon. Waves building to 3 to 5 feet occasionally to 7 feet.
.THURSDAY NIGHT...Southeast winds 15 to 25 knots veering south
after midnight, then diminishing to 10 to 20 knots late. A chance
of showers through midnight. A chance of thunderstorms. Showers
likely after midnight. Waves building to 3 to 6 feet occasionally
to 8 feet, then subsiding to 2 to 4 feet.
.FRIDAY...South winds 5 to 15 knots. A chance of showers and a
slight chance of thunderstorms. Waves subsiding to calm to
2 feet.
.FRIDAY NIGHT...South winds 5 to 15 knots becoming west less than
10 knots after midnight. Waves calm to 2 feet.
.SATURDAY...West winds 5 to 15 knots backing south by mid
afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...South winds 5 to 15 knots backing north after
midnight. Waves calm to 2 feet.
.SUNDAY...West winds 10 to 20 knots becoming north 5 to 15 knots.
A chance of showers. Waves calm to 2 feet.
.MONDAY...Northeast winds 10 to 20 knots veering east. A chance
of showers. Waves building to 1 to 3 feet.

$$

LSZ265-190415-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
406 PM EDT Wed Sep 18 2024

.LATE THIS AFTERNOON...Southeast winds 10 to 20 knots. Waves 1 to
3 feet.
.TONIGHT...Southeast winds 10 to 20 knots veering south after
midnight. Waves subsiding to calm to 2 feet.
.THURSDAY...Southeast winds 10 to 20 knots increasing to 15 to
25 knots late. Waves building to 2 to 4 feet.
.THURSDAY NIGHT...Southeast winds 15 to 25 knots veering south
after midnight, then diminishing to 10 to 20 knots late. A chance
of showers through midnight. A chance of thunderstorms. Showers
likely after midnight. Waves building to 3 to 5 feet occasionally
to 7 feet, then subsiding to 1 to 3 feet.
.FRIDAY...South winds 10 to 20 knots backing southeast by mid
afternoon. Showers likely through early afternoon. A chance of
thunderstorms. A chance of showers by mid afternoon. Waves
subsiding to calm to 2 feet.
.FRIDAY NIGHT...South winds 5 to 15 knots veering southwest after
midnight. Waves calm to 2 feet.
.SATURDAY...West winds 5 to 15 knots becoming east 10 to 20 knots
by mid afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...Southeast winds 5 to 15 knots becoming west
10 to 20 knots after midnight. Waves calm to 2 feet.
.SUNDAY...Northwest winds 10 to 20 knots veering north. A chance
of showers. Waves calm to 2 feet.
.MONDAY...Northeast winds 10 to 20 knots veering east. A chance
of showers. Waves calm to 2 feet.

$$

LSZ266-190415-
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-
406 PM EDT Wed Sep 18 2024

.LATE THIS AFTERNOON...Southeast winds 10 to 20 knots. Waves 1 to
3 feet.
.TONIGHT...South winds 10 to 20 knots. Waves 1 to 3 feet.
.THURSDAY...South winds 10 to 20 knots backing southeast in the
afternoon. Waves building to 2 to 4 feet.
.THURSDAY NIGHT...South winds 15 to 25 knots. A chance of showers
and thunderstorms. Waves building to 3 to 5 feet occasionally to
7 feet, then subsiding to 2 to 4 feet.
.FRIDAY...South winds 10 to 20 knots. Showers likely through
early afternoon. A chance of thunderstorms. A chance of showers
by mid afternoon. Waves subsiding to calm to 2 feet.
.FRIDAY NIGHT...South winds 5 to 15 knots. A chance of showers
and thunderstorms. Waves calm to 2 feet.
.SATURDAY...Southwest winds 5 to 15 knots backing east by mid
afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...Southeast winds 5 to 15 knots veering south
after midnight. Waves calm to 2 feet.
.SUNDAY...Northwest winds 10 to 20 knots veering north. A chance
of showers. Waves calm to 2 feet.
.MONDAY...Northeast winds 10 to 20 knots veering east. A chance
of showers. Waves building to 1 to 3 feet, then subsiding to calm
to 2 feet.

$$

LSZ267-190415-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
406 PM EDT Wed Sep 18 2024

.LATE THIS AFTERNOON...Southeast winds 10 to 20 knots. Waves calm
to 2 feet.
.TONIGHT...South winds 10 to 20 knots. Waves calm to 2 feet.
.THURSDAY...Southeast winds 10 to 20 knots. Waves calm to 2 feet.
.THURSDAY NIGHT...South winds 10 to 20 knots backing southeast
after midnight. A slight chance of showers and thunderstorms
after midnight. Waves building to 1 to 3 feet.
.FRIDAY...South winds 10 to 20 knots backing southeast by mid
afternoon. Showers likely and a chance of thunderstorms. Waves
subsiding to calm to 2 feet.
.FRIDAY NIGHT...Southeast winds 10 to 20 knots becoming south
5 to 15 knots after midnight. Showers likely through midnight. A
chance of thunderstorms. A chance of showers after midnight.
Waves calm to 2 feet.
.SATURDAY...South winds 5 to 15 knots backing southeast by mid
afternoon. Waves calm to 2 feet.
.SATURDAY NIGHT...Southeast winds 5 to 15 knots becoming south
10 to 20 knots after midnight. Waves calm to 2 feet.
.SUNDAY...South winds 10 to 20 knots backing northeast. A chance
of showers. Waves calm to 2 feet.
.MONDAY...Northeast winds 10 to 20 knots veering east. A chance
of showers. Waves building to 1 to 3 feet, then subsiding to calm
to 2 feet.

$$

LSZ261-190415-
MAFOR 1821/
Superior West 12310 11410 11420 11310 12320 11310. Waves 1 to 2
feet.

Superior North Central 12320 12420 11410 11420 12320. Waves 1 to
4 feet.

Superior South Central 12320 14410 12320. Waves 1 to 3 feet.

Superior East 12310 13410 11300 12310. Waves 1 to 2 feet.

$$

JSS

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

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