The past couple of weeks have been very quiet in the northwest. And quiet weather has translated into beautiful weather. Sunshine has been plentiful, and rain and snow have been absent. One big downside of this tranquil stretch, has been poor air quality. With no storms coming through to mix up the atmosphere, levels of air pollutants have been increasing. Air Stagnation Alerts have been in effect for over a week in many areas. You can actually see the hazy conditions against the mountains in the picture of Eugene, Oregon from earlier today.
But things are about to change. The ridge of high pressure that has been blocking storms from the Pacific Ocean, is breaking down. Low pressure is taking its place. This will allow several waves of energy to come onshore, bringing rain to the valleys, and snow to the mountains. The whole process will circulate the atmosphere, replacing older stagnant air, with new fresh air. The raindrops and snowflakes will also scour out pollutants, thereby improving air quality.
It looks like moisture will start arriving in Seattle and Portland early on Friday morning.
By Friday afternoon, snow will blanket eastern Oregon, the chimney of Idaho, and western Montana. This is the first in a series of Pacific storms that will cover most areas in the northwest with snow and rain through the weekend.
The following picture shows the coverage and amounts of snow and rain across the region by Monday. Generally, rainfall totals will be less than an inch through Monday morning. Snowfall totals will range from one to four inches, except in the higher elevations of the Cascades, Bitteroots, and Rockies. Snow could easily surpass the one foot mark in those spots.
The return to an active weather pattern is a good thing. The rain helps replenish the water supply. The snow pack also helps this cause when it melts. Beforehand, it benefits skiers and ski resorts during the winter season. And of course, once the storms pass, air quality will be much improved. However, in exchange for all of this, the gloomy wet conditions must return for a while. Look at the extended forecast for Seattle and Portland. Just as the beautiful weather hung around a while, so too might the clouds and showers.
But for other towns like Spokane, there should be a bit more sunshine in-between rounds of snow and rain.
For WeatherNation: Meteorologist Matt Monroe
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