A cold front is due to arrive late this weekend, bringing some of the chilliest temperatures of the season and maybe a dusting of lowland snow to start next week.
“Tuesday looks to be the coldest day,” said meteorologist Johnny Burg at the National Weather Service office in Seattle. “It’ll last for a couple of days.”
After a rainy weekend with highs from the mid-40s to around 50, sharply colder weather barges in Sunday afternoon. There’s a chance of showers Sunday night, with lows in the low to mid-30s and the possibility of snow as low as 500 feet.
The biggest threat will be the possibility of black ice on roadways, especially for Monday and Tuesday morning commuters.
“There will be colder air coming behind the rain,” Burg said. “There’s the possibility of lowland snow, but it’s looking pretty low. This is still too far in advance to pin down the details.”
By Monday and Tuesday, it’ll be mostly sunny with daytime temperatures barely reaching 40 degrees. There’s a small chance of showers both Monday and Tuesday. Overnight lows will be in the 20s.
Burg said the biggest threat from the upcoming cold snap will be the possibility of black ice on roadways, especially for Monday and Tuesday morning commuters.
“The mountains could see another dose of snow,” Burg said. “If you are planning travel or activities in the mountains, be aware of that.”
By Thursday, temperatures will begin warming back into the 40s.
“If there’s anything left on the ground, it will be melting,” Burg said.
Meanwhile, hillsides across Western Washington remain saturated from above-normal rainfall in November, leading to a continued threat of landslides, Burg said.
Throughout the North Cascades, avalanche danger has eased to “moderate” above and below the treeline, according to the Northwest Avalanche Center. Backcountry travelers should “watch for increasing avalanche danger in the afternoon and be prepared to change plans if conditions warrant,” forecasters advise at nwac.us.
Next week’s brush with freezing weather could be just a glimpse of things to come in 2017, as forecasters see a weak La Niña pattern forming. La Niña refers to the seasonal cooling of waters in the equatorial Pacific, which can disrupt normal weather patterns. It’s the climatological counterpart to El Niño.
The transition to La Niña hasn’t changed the weather service’s long-range expectations for January, February and March, which see a greater chance for above-normal precipitation and below-normal temperatures across Western Washington.
“We are now under a La Niña, which means for us a cooler and wetter than normal winter,” Burg said.