Big pattern change to usher cooler air, needed rain into the Northwest
A dry, warm September in the Northwest is about to give way, with cooler, fall-like weather set to arrive as October approaches.
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A dry, warm September in the Northwest is about to give way, with cooler, fall-like weather set to arrive as October approaches.
"The first significant fall storm of the season will barrel into the Northwest in two waves Monday into Tuesday," AccuWeather Senior Meteorologist Chad Merrill said.
Rain, clouds and cool air have been absent for much of the month, resulting in areas of expanding drought from coastal Oregon to much of Washington and into the northern Rockies.
"Seattle had its fifth driest stretch from June 1 to Sept. 25, with only 2.06 inches of rain, so the rain will be a welcome sight," Merrill said.
Temperatures have been a few degrees above the monthly historical average in Seattle and Portland, Oregon, and as much as 4-8 degrees above typical September levels farther inland.
The last weekend of September was dry for outdoor plans, from fall festivals to hikes and college football. Sunday evening marked a change in pattern with increasing clouds and some rain falling along the Washington and Oregon coasts.
The first storm will continue to soak the the Pacific Northwest through Monday, followed by a second, stronger storm Tuesday into Wednesday.
"Rain totaling 1-2 inches will pelt the coast early this week with rain amounts tapering to around a half of an inch along the Interstate 5 corridor," Merrill said. "The rain will help to keep the drought from deteriorating across the Northwest and the added moisture will lower the fire risk significantly early this week in the Northwest."
The recent stretch of dry weather will help keep the risk of flash flooding low, despite the storms. However, motorists should use caution on interstates and winding roads, where rainfall may reduce visibility and create slick conditions.
"The Cascades will end up with about an inch of rain and it will be too warm for any snowfall, except over the highest peaks late Tuesday into early Wednesday," Merrill said.
The second storm coming into the West from late Tuesday into Wednesday will dip far enough south to infuse some moisture leftover from what was Hurricane Narda.
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"This will lead to pockets of flooding along the northern California to the Northwest Coast," Merrill said. "Wind gusts of 30-50 mph will accompany the rain and will trigger localized power outages."
Some rain from each storm will extend into Northern California, with a few inches possible in northwestern coastal areas through early this week.
Temperatures will be 5-15 degrees below the historical average during the rainy stretch, putting high temperatures generally in the 60s and lower 70s during the early and middle part of the week.
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