Rain to return across northwestern US on first day of spring

By Brett Rathbun, AccuWeather.com Meteorologist

March 18,2016; 10:55PM,EDT

 

 

After much of the northwestern United States enjoys a rare multiple-day stretch of dry weather to end the week, rain will make a return by the first day of spring.
A strong area of high pressure positioned across the Pacific Northwest will be responsible for dry weather through the first half of the weekend.
Prior to this week, the last time Seattle and Portland, Oregon, had a stretch of multiple days with dry weather was from Feb. 6-9 and Feb. 23-25, respectively. Persistent rainstorms unleashed an entire month's worth of rain from Seattle to Portland by March 14.
By the first day of spring, the high will weaken and allow a storm to roll onshore.

"After the first prolonged stretch of dry weather in quite some time this week, unsettled weather will return to the region by Sunday," AccuWeather Meteorologist Ryan Adamson said.
There may be a brief shower or sprinkle ahead of this storm across portions of western Washington and Oregon and northern California spanning Friday night into Saturday night.
Rain will reach the coastal sections of Washington, Oregon and northern California during Sunday morning and continue to press inland through the afternoon.
Enough mild air will be in place for precipitation to start in the form of rain across the entire region, including above pass level. As colder air builds in behind the storm, snow levels will begin to fall.
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"At the onset of the event, snow levels will be fairly high, initially around 7,000 to 8,000 feet, before lowering to 4,000 to 6,000 feet by Monday," Adamson said.
Snow levels are expected to remain above Snoqualmie Pass height until at least late Tuesday.
The storm will continue to press inland on Monday and bring rain and mountain snow to portions of the northern Rockies. Rain and mountain snow will continue from Washington to northern California. This storm will not be strong enough to bring any significant rain to Southern California.

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"Snow levels across the northern Rockies on Monday will also be high, around 7,000 to 8,000 feet, before falling during Monday night and Tuesday," Adamson said.
Between 1 and 2 inches of rain could fall from portions of western Washington to northern California. Between 2 and 4 inches of rain could fall in northwestern California.
Due to the record rainfall that fell this winter plus the amount of rain expected, there could be localized flooding, especially in low-lying and poor drainage areas.
"Precipitation will become more showery by Tuesday, with rain possibly pushing farther southward across California," Adamson said.
While additional significant storms should stay away during the second half of next week, showers may stick around.