By Robert Mittendorf

The Bellingham Herald

BELLINGHAM — This weekend’s full moon will be the largest and brightest in half a century, but good luck trying to see it: Western Washington’s forecast is for rain Sunday and partly cloudy skies Monday, when the November “supermoon” arrives.

November’s full moon is called a Beaver Moon or Frost Moon in Algonquin lore, because this was the time to set beaver traps before the swamps froze, according to the Farmers Almanac. This month, the full moon arrives at 5:52 a.m. PST Monday, as it is setting in the west.

It’s called a supermoon because the full lunar face is illuminated when the moon is at perigee — when it’s closest to the Earth in its elliptical orbit. This year, the moon reaches perigee about the same time it turns full.

A supermoon appears about 30 percent brighter and 14 percent larger than a regular full moon, according to earthsky.org. It is the second of three consecutive supermoons, and will be closer to Earth than it’s been since Jan. 26, 1948. The moon won’t come this close to Earth again until Nov. 25, 2034.

Because the moon is full at dawn Monday, it will appear full to casual observers both Sunday and Monday nights. Expect a good amount of Northwest cloud cover those nights, forecasters said. Sunday morning just before dawn, and possibly Monday night, might offer a few breaks in the clouds for committed skywatchers.

“I’m skeptical that you’ll be able to see it,” said meteorologist Andy Haner at the National Weather Service in Seattle. Sunday night calls for rain, with mostly cloudy skies on Monday night. “That sounds like pretty poor viewing conditions,” Haner said.

Every year from November through February, the highest tides — called “king tides” — sweep onto the shores during full moons. This is due to the combination of gravity from the moon and sun being the closest to Earth that they will be all year. The tides get even higher during “supermoons” simply because the moon is closer to Earth, The Washington Post reports.

Full moons of winter can sometimes cause coastal flooding, and more so with supermoons, because they bring higher “king tides.” A 9-foot high tide is expected at 3:02 p.m. Sunday and at 3:39 p.m. Monday, according to the tides app Rise. Blaine will see 9.8-foot high tides at 3:25 p.m. Sunday and at 4:04 p.m. Monday.

But don’t expect hazardous coastal conditions.

“Eleven feet is high. Nine feet is a pretty normal high for the month,” especially without stormy weather, Haner said.