Great Lakes Forecast
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409
FZUS63 KMQT 230802
GLFLS

Open Lake Forecast for Lake Superior
National Weather Service Marquette MI
402 AM EDT Mon Oct 23 2017

For waters beyond five 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 low pressure trough of 29.7 inches over the
Northern Plains will reach central Lake Superior this afternoon.
The trough will then give way to low pressure of 29.5 inches
organizing over the Ohio Valley today. As this low lifts north to
far northern Lake Michigan by Tuesday morning, it will rapidly
deepen to 28.9 inches. The low will then move to Lake Huron
Tuesday night as it weakens to 29.3 inches. As the low weakens
further on Wednesday while lifting toward Quebec, a 29.7 inch high
pressure ridge will reach Lake Superior. Another low pressure of
29.4 inches over the Northern Plains Wednesday evening will track
east, reaching the Upper Great Lakes Friday morning.

LSZ162-231615-
Lake Superior west of a line from Saxon Harbor WI to Grand
Portage MN beyond 5NM-
402 AM EDT Mon Oct 23 2017 /302 AM CDT Mon Oct 23 2017/

...GALE WARNING IN EFFECT FROM LATE TONIGHT THROUGH LATE TUESDAY
NIGHT...

.EARLY THIS MORNING...South winds 15 to 25 knots. A slight chance
of showers. Waves 3 to 5 feet occasionally to 7 feet.
.TODAY...South winds 10 to 20 knots veering west late. A slight
chance of showers. Waves subsiding to calm to 2 feet.
.TONIGHT...North winds 20 to 30 knots increasing to gales to
45 knots after midnight. A chance of showers. Waves building to
8 to 11 feet occasionally to 14 feet.
.TUESDAY...North gales to 45 knots. A chance of showers. Waves
building to 10 to 14 feet occasionally to 18 feet, then subsiding
to 8 to 11 feet occasionally to 14 feet.
.TUESDAY NIGHT...North gales to 35 knots becoming northwest 15 to
25 knots after midnight. A slight chance of rain showers after
midnight. Waves subsiding to 2 to 4 feet.
.WEDNESDAY...West winds 10 to 20 knots. Waves subsiding to calm
to 2 feet.
.WEDNESDAY NIGHT...South winds 10 to 20 knots backing southeast
after midnight. Waves building to 1 to 3 feet.
.THURSDAY...South gales to 35 knots becoming north gales to
40 knots. Rain showers. Waves building to 7 to 10 feet
occasionally to 13 feet.
.FRIDAY...North gales to 40 knots becoming northwest 15 to
25 knots. A chance of rain showers. A chance of snow showers.
Waves subsiding to 1 to 3 feet.

$$

LSZ263-231615-
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-
402 AM EDT Mon Oct 23 2017

...STORM WARNING IN EFFECT FROM TUESDAY MORNING THROUGH TUESDAY
EVENING...

.EARLY THIS MORNING...South winds 10 to 20 knots. A slight chance
of showers. Waves 3 to 5 feet occasionally to 7 feet.
.TODAY...South winds 10 to 20 knots becoming southwest 5 to
15 knots in the afternoon, then veering west late. A slight
chance of showers. Waves subsiding to calm to 2 feet.
.TONIGHT...North winds 15 to 25 knots increasing to gales to 45
knots late. A chance of showers. Waves building to 10 to 14 feet
occasionally to 18 feet.
.TUESDAY...North storm force winds to 60 knots. Rain showers.
Waves building to 15 to 20 feet occasionally to 25 feet, then
subsiding to 12 to 17 feet occasionally to 21 feet.
.TUESDAY NIGHT...North gales to 45 knots diminishing to 20 to
30 knots after midnight. A chance of rain showers. Waves
subsiding to 3 to 6 feet occasionally to 8 feet.
.WEDNESDAY...Northwest winds 5 to 15 knots backing west by mid
afternoon. A chance of rain showers. Waves subsiding to calm to
2 feet.
.WEDNESDAY NIGHT...South winds 5 to 15 knots becoming southeast
10 to 20 knots after midnight. Waves building to 1 to 3 feet.
.THURSDAY...Southeast winds 20 to 30 knots becoming north gales
to 40 knots. Rain showers. Waves building to 2 to 4 feet, then
subsiding to 1 to 3 feet.
.FRIDAY...North gales to 40 knots becoming northwest 20 to
30 knots. Rain showers likely, then a chance of rain showers.
Waves subsiding to 1 to 3 feet.

$$

LSZ264-231615-
Lake Superior from Upper Entrance to Portage Canal to Manitou
Island MI 5NM off shore to the US/Canadian Border-
402 AM EDT Mon Oct 23 2017

...STORM WARNING IN EFFECT FROM LATE TONIGHT THROUGH TUESDAY
EVENING...

.EARLY THIS MORNING...Southwest winds 10 to 20 knots. Waves 2 to
4 feet.
.TODAY...South winds 5 to 15 knots backing southeast late. Waves
subsiding to 1 to 3 feet.
.TONIGHT...North winds 10 to 20 knots increasing to storm force
winds to 50 knots late. A chance of showers through midnight,
then showers after midnight. Waves subsiding to calm to 2 feet,
then building to 12 to 17 feet occasionally to 21 feet.
.TUESDAY...North storm force winds to 60 knots. A few hurricane
force wind gusts to 67 knots. Rain showers. Waves building to 17
to 22 feet occasionally to 28 feet, then subsiding to 15 to 20
feet occasionally to 25 feet.
.TUESDAY NIGHT...North storm force winds to 55 knots diminishing
to gales to 35 knots after midnight. Rain showers likely through
midnight, then a slight chance of rain showers after midnight.
Waves subsiding to 5 to 8 feet occasionally to 10 feet.
.WEDNESDAY...Northwest winds 15 to 25 knots diminishing to 5 to
15 knots by mid afternoon. Waves subsiding to calm to 2 feet.
.WEDNESDAY NIGHT...Southeast winds 5 to 15 knots increasing to
10 to 20 knots after midnight. Waves building to 1 to 3 feet.
.THURSDAY...Southeast winds 15 to 25 knots becoming northeast
gales to 40 knots. A chance of rain showers, then rain showers.
Waves building to 9 to 12 feet occasionally to 15 feet.
.FRIDAY...North gales to 40 knots. Rain showers likely, then a
chance of rain showers. Waves subsiding to 3 to 5 feet
occasionally to 7 feet.

$$

LSZ265-231615-
Lake Superior West of Line from Manitou Island to Marquette MI
Beyond 5NM from shore-
402 AM EDT Mon Oct 23 2017

...STORM WARNING IN EFFECT FROM LATE TONIGHT THROUGH TUESDAY
EVENING...

.EARLY THIS MORNING...Southwest winds 10 to 20 knots. Waves 1 to
3 feet subsiding to calm to 2 feet.
.TODAY...South winds 10 to 20 knots diminishing to 5 to 15 knots
in the afternoon, then backing southeast late. Waves building to
1 to 3 feet, then subsiding to calm to 2 feet.
.TONIGHT...Northeast winds 5 to 15 knots becoming north gales to
35 knots after midnight, then increasing to storm force winds to
55 knots late. A chance of showers through midnight, then showers
after midnight. Waves building to 15 to 20 feet occasionally to
25 feet.
.TUESDAY...North storm force winds to 60 knots. A few hurricane
force wind gusts to 67 knots. Showers. Waves building to 20 to 25
feet occasionally to 31 feet, then subsiding to 17 to 22 feet
occasionally to 28 feet.
.TUESDAY NIGHT...North storm force winds to 55 knots diminishing
to gales to 35 knots after midnight. Rain showers through
midnight, then a chance of rain showers after midnight. Waves
subsiding to 7 to 10 feet occasionally to 13 feet.
.WEDNESDAY...Northwest winds 15 to 25 knots diminishing to 10 to
20 knots by mid afternoon. Waves subsiding to 1 to 3 feet.
.WEDNESDAY NIGHT...South winds 10 to 20 knots. Waves subsiding to
calm to 2 feet.
.THURSDAY...South winds 15 to 25 knots becoming north gales to
35 knots. A chance of rain showers, then rain showers. Waves
building to 2 to 4 feet, then subsiding to 1 to 3 feet.
.FRIDAY...Northwest gales to 35 knots diminishing to 20 to
30 knots. Rain showers likely. Waves building to 8 to 11 feet
occasionally to 14 feet, then subsiding to 3 to 5 feet
occasionally to 7 feet.

$$

LSZ266-231615-
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-
402 AM EDT Mon Oct 23 2017

...STORM WARNING IN EFFECT FROM LATE TONIGHT THROUGH TUESDAY
EVENING...

.EARLY THIS MORNING...South winds 10 to 20 knots. Waves 2 to
4 feet.
.TODAY...South winds 10 to 20 knots becoming southeast 5 to
15 knots late. Waves subsiding to 1 to 3 feet, then building to
2 to 4 feet.
.TONIGHT...Northeast winds 10 to 20 knots becoming north gales to
45 knots after midnight, then increasing to storm force winds to
60 knots late. A chance of showers through midnight, then showers
after midnight. Waves subsiding to calm to 2 feet, then building
to 15 to 20 feet occasionally to 25 feet.
.TUESDAY...North storm force winds to 60 knots. A few hurricane
force wind gusts to 67 knots. Showers. Waves building to 22 to 27
feet occasionally to 34 feet, then subsiding to 17 to 22 feet
occasionally to 28 feet.
.TUESDAY NIGHT...North storm force winds to 55 knots diminishing
to gales to 35 knots after midnight. Rain showers. Waves
subsiding to 9 to 12 feet occasionally to 15 feet.
.WEDNESDAY...North winds 20 to 30 knots becoming northwest 10 to
20 knots by mid afternoon. Waves subsiding to 1 to 3 feet.
.WEDNESDAY NIGHT...South winds 10 to 20 knots. Waves subsiding to
calm to 2 feet.
.THURSDAY...South winds 15 to 25 knots becoming northeast gales
to 40 knots. A chance of rain showers, then rain showers. Waves
building to 7 to 10 feet occasionally to 13 feet.
.FRIDAY...Northwest gales to 40 knots. Rain showers likely. Waves
building to 8 to 11 feet occasionally to 14 feet, then subsiding
to 3 to 6 feet occasionally to 8 feet.

$$

LSZ267-231615-
Lake Superior from Grand Marais MI to Whitefish Point MI 5NM off
shore to the US/Canadian border-
402 AM EDT Mon Oct 23 2017

...STORM WARNING IN EFFECT FROM LATE TONIGHT THROUGH TUESDAY
AFTERNOON...

.EARLY THIS MORNING...Southwest winds 10 to 20 knots. Patchy fog.
Waves 1 to 3 feet.
.TODAY...South winds 10 to 20 knots becoming east 5 to 15 knots
late. A slight chance of showers by mid afternoon. Waves
subsiding to calm to 2 feet.
.TONIGHT...Northeast winds 15 to 25 knots increasing to storm
force winds to 60 knots after midnight. A chance of showers
through midnight, then showers after midnight. Waves building to
15 to 20 feet occasionally to 25 feet.
.TUESDAY...Northeast storm force winds to 60 knots diminishing to
gales to 45 knots in the afternoon, then becoming east gales to
35 knots late. Showers. Waves subsiding to 7 to 10 feet
occasionally to 13 feet.
.TUESDAY NIGHT...North gales to 40 knots. Rain showers. Waves
building to 8 to 11 feet occasionally to 14 feet, then subsiding
to 6 to 9 feet occasionally to 11 feet.
.WEDNESDAY...North winds 20 to 30 knots becoming northwest 15 to
25 knots by mid afternoon. A chance of rain showers. Waves
subsiding to 1 to 3 feet.
.WEDNESDAY NIGHT...Northwest winds 10 to 20 knots backing south
after midnight. Waves subsiding to calm to 2 feet.
.THURSDAY...Southeast winds 15 to 25 knots becoming south 20 to
30 knots. A chance of rain showers. Waves building to 3 to 6 feet
occasionally to 8 feet.
.FRIDAY...Northwest gales to 35 knots diminishing to 20 to
30 knots. Rain showers likely. Waves building to 7 to 10 feet
occasionally to 13 feet, then subsiding to 3 to 6 feet
occasionally to 8 feet.

$$

LSZ261-231615-
MAFOR 2309/
Superior West...Gale Warning in effect...11430 11420 11520 11510
11610 11830 11840 11850. Chance of showers overnight. Waves 1 to
5 feet today building to 6 to 9 feet tonight.

Superior North Central 11520 12420 11410 11300 11110 11130 11856.
Chance of showers after midnight tonight. Waves 1 to 4 feet
today building to 5 to 8 feet tonight.

Superior South Central...Storm Warning in effect...11510 13410
11310 11210 11130 11866 19876. Chance of showers after midnight
tonight. Waves 1 to 3 feet today building to 7 to 10 feet
tonight.

Superior East...Storm Warning in effect...13410 11310 11210 11120
11156 11176. Chance of showers late this evening. Waves 1 to 3
feet today building to 10 to 14 feet tonight.

$$

Rolfson

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

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



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