Cooler Air Moves through the Northwest this Week
A large trough is swinging across the Western US. bringing some valley rain and high mountain snow. Temperatures will also see a significant drop as the trough brings in much colder air farther inland across the Northwest.
The cold air has already settled into coastal regions. The average high this time of year in Seattle is around 65°, but highs in the 5os and low 60s have been felt since last week. Places farther inland will begin to feel the colder temperatures throughout the next 24 to 48 hours.
The temperature trend will continue a downward turn today (Thursday). The Snake River Valley will see significant temperature drop over the next several days. Boise, ID could see a 20 degree temperature drop taking highs from 10 degree above average to 10 degrees below average.
End of the Week
The extended period shows several days of temperatures remaining cooler than average for this time of year. Highs will be in the 50s and 60s.
It takes a few more days for the colder air mass to move inland. The trend in places like Billings, MT will seem a bit more drastic with the mercury drop over the extended forecast. It was in the 80s Wednesday, but high temperatures will drop into the 40s and 50s next week.
The long range forecast for temperatures, issued by the Climate Prediction Center, shows the 6 to 10 day outlook with a high confidence these cooler than average conditions continue into next week.