Several Pacific storm systems will dive into the northwestern United States during the first half of this week, each one delivering a round of rain, cool air and mountain snow. For the Cascades, this will be the first snow of the season.
“As these storms sweep into the Northwest this week, residents of Washington, Oregon, Idaho and western Montana and Wyoming will be hard-pressed to find a dry day,” AccuWeather Meteorologist Faith Eherts said.
The first storm system will move into the region Monday, while a stronger second storm system will quickly follow on the heel’s of the first, arriving Tuesday night into Wednesday.
Folks in the I-5 corridor from Seattle to Portland and farther south to Eugene, Oregon, can expect cool and wet conditions through Wednesday. The heaviest rain is expected Tuesday night.
Low clouds and rain will lead to dreary conditions and travel delays in the air and on the ground. Wet roads can make for slippery travel and slower traffic. Areas that experience a period of heavy rain could experience ponding of water on roadways.
Through Wednesday, areas west of the Cascades could have 0.75 to 1.50 inches of rain. Higher amounts are expected closer to the coast.
Strong winds and rough seas will batter the Washington and Oregon coasts. Wind gusts of 45 to 55 mph will be possible, especially Tuesday night.
There will be enough cool air and instability in the region that a few thunderstorms will be possible. Downpours and small hail may accompany some of them.
Temperatures each afternoon through the middle of the week will run 6 to 12 F below normal, which is on par with temperatures in mid-October.
The arrival of cool air will help deliver the first snow of the season to the Cascades and second round of snow to the northern Rockies.
“While a chilly rain will pester those living near the coast and in the valleys and plains of the interior Northwest, anyone venturing above 5,000 feet elevation can expect snow,” Eherts said.
Generally, 3 to 6 inches of snow is expected, but some of the highest peaks could have up to a foot of snow. Motorists will not have to worry about accumulating snow at the major passes, but wet roads will still lead to slippery conditions.
For many in the Northwest, the arrival of cool and wet weather couldn’t have come sooner. Dozens of wildfires continue to burn across several states. According to the National Interagency Fire Center, wildfires have consumed over 8 million acres through mid-September this year, ranking second highest over the same time span in the past 10 years.
“While putting a clear end to the summer season, these dreary and cool conditions will help to improve air quality, dampen wildfires and bring relief to drought-ridden areas,” Eherts said.
While the rain will mostly bring positive impacts, there will be an increased risk for runoff and mudslides around areas freshly burned by wildfires.