Double header of storms in the West this week
Two strong storms will advance across the West this week with rain, strong winds and the biggest thump of snow to the Sierra so far this season. Forecasters warn that blizzard conditions will be possible in the Sierra.
A Bear Valley, California, resident said the area received up to 159 inches of snow as of Feb. 20, with more snow heading their way. Here’s how locals in the area have been going about their days.
This week, an active pattern is setting up once again across the Northwest U.S. with two primary storms expected to sweep across the region. AccuWeather meteorologists are highlighting the risk for wintry conditions to mix down to nearly sea level Tuesday morning, impacting portions of the Seattle and Portland, Oregon, landscapes.
Early week storm rapidly lowered snow levels
The first of the two storms will continue to track southeastward from southwestern Canada into the North Central states, swinging a potent cold front from Washington and Oregon into the Rocky Mountains Tuesday morning. As this frontal boundary crosses the western states from north to south, cooler air will spill into the region and continue to usher in wintry conditions.
Heavy mountain snow fell across the Cascades and northern Rockies through Monday night. As the front progressed into the Four Corners region into Monday night, snow expanded to the Colorado Rockies and higher terrain of northern New Mexico. By Tuesday morning, even the higher elevations of northeastern Arizona will see a bit of accumulating snow.
Snow levels dropped to pass height late Sunday, including Stevens, Snoqualmie and White Pass. Snowfall totals can range from 1-2 feet across the higher elevations of the Washington and Oregon Cascades from Sunday to Tuesday night. Travel will continue to be difficult across the mountains early this week as snow levels rapidly fall and heavy snow spreads across the region.
Across the lower elevations, forecasters highlight that rain and snow can mix in as snow levels drop closer to sea level early this week. In Seattle, snow mixed with rain for a time Monday evening, and a few wet snowflakes can mix in again during the morning hours on Tuesday.
Overnight temperatures hovered near freezing in Seattle Monday night, the first time so far this February. In Portland, Oregon, precipitation came in the form of rain through Monday, but can change over to a mixture of rain and snow early Tuesday morning.
Next storm on the horizon
By late Tuesday into Wednesday, the second storm will begin to spread moisture into coastal Washington and Oregon. Rainfall rates along the coast and in upslope regions can trend higher than earlier in the week, with 24-hour totals potentially ranging upwards from 1.50-2.50 inches between Wednesday and Thursday, elevating the risk for flash flooding.
"The storm that arrives Tuesday night in the Northwest will be more prolonged than the early week storm, as it is expected to linger into the weekend," explained AccuWeather Senior Meteorologist Adam Douty.
The storm will slowly progress southward along the West Coast states from Wednesday to Saturday, ushering in a cooler air mass from Washington to Central California.
"The storm along the West Coast later this week will feature a much stronger dip in the polar jet stream which will allow for cold air from the Gulf of Alaska to dump into the region over the weekend. This is expected to yield an event with generally lower freezing levels, and its largely due to the dip in the polar jet stream," added AccuWeather Meteorologist Joseph Bauer.
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As snow levels rise around midweek for locations like Seattle, there will be less of a chance for snowflakes in the lower elevations. By Friday night; however, temperatures are projected to drop near freezing once again for the Emerald City, bringing back the risk for wintry weather.
Biggest thump of snow to the Sierra this season on the way
Farther south into Northwest California, rain will arrive during the day on Wednesday. Snow will begin to spread across the Klamath Mountain range and northern portions of the Sierra range by Wednesday night.
This event will have the capacity to spread yards of snow across the Sierra Nevada from late Wednesday to Sunday morning, paired with gusty winds. The highest snowfall totals are expected across the northern and central Sierra Nevada with widespread amounts ranging from 4-8 feet above 5,000 feet. Some of the ridges and peaks in the high country may approach 10 feet of fresh snow.
AccuWeather Chief Broadcast Meteorologist Bernie Rayno explained, "This [storm] is not a rainstorm, but a mountain snowstorm. Extreme conditions will occur in mountain ranges such as the Sierra and Siskiyous, resulting in road and pass closures."
As the storm advances southward from mid-to-late week, there will be an uptick in winds from the Northwest to the Southwest, particularly across the higher terrain. From Thursday to Friday, blustery winds ranging from 40-60 mph across the northern and central Sierra, resulting in blizzard-like conditions as heavy snow expands across the mountain range. Even higher gusts can be possible at the highest mountain peaks.
"Snow levels will start near to slightly below pass level in the Sierra and can fall well below pass level by this weekend. Even in the coastal mountains around the Bay Area in California, snow levels could fall low enough for snow in these areas by Saturday," explained Bauer.
Compared to the historical average, California is currently pacing at 82% of their typical snow water equivalent, according to the California Department of Water Resources. Forecasters say that Sierra snowfall expected during the second half of this week could be the biggest dump of snow of the season so far and could help to 'catch up' the lagging snow totals this winter.
"After a very slow start to the snow season in the Sierra, this storm will not only push snow totals above the historical average so far but likely bring total to the seasonal averages with two months left in the snow season," noted Rayno.
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