Several significant storms, carrying ample moisture from the Pacific, are expected to hit the West Coast of the United States in the coming days. AccuWeather meteorologists are cautioning that these storms will heighten the threat of flooding and mudslides. While not all of them will reach bomb cyclone status, the accumulation of rain from Northern California to western Washington is cause for concern. Up to 2 feet of rain is anticipated, particularly on mountainous slopes facing west, through the week after Christmas, according to AccuWeather Meteorologist Danielle Ehresman.
AccuWeather Senior Meteorologist Brett Anderson warns that one or more of these storms may form an atmospheric river, channeling copious amounts of rain akin to a fire hose or snow like a snowmaking machine toward parts of the West Coast. These storms this weekend will serve as a prelude to what’s to come in the last week of December. The heaviest rain and mountain snow are predicted just before and after Christmas.
Motorists traveling along the Interstate 5 corridor from San Francisco to Seattle can expect multiple rounds of heavy rain, with the possibility of standing water on roads where drainage is poor. Flash flooding of small streams is likely as each storm brings more runoff, raising the risk of significant river flooding, especially in areas with short-run rivers originating from various mountain ranges.
The number of mudslides and debris flows, particularly in areas previously affected by wildfires, is expected to rise as the soil becomes saturated. Washouts on secondary roads in hilly regions are also a concern. Snow levels in the mountains will fluctuate with each storm, starting high but gradually lowering as colder storms arrive around Christmas.
While snow levels may remain above pass level for the most part, there will be times when freezing temperatures and snowfall create hazardous conditions along routes such as Donner Pass in California and Snoqualmie Pass in Washington, particularly next week. In the high country, significant snow accumulations of 5-10 feet are anticipated in the Cascades and northern Sierra Nevada. This shifting snow cover raises the risk of avalanches as the snow becomes more unstable with each storm.
Although Southern California is expected to receive minimal moisture from these storms, it is crucial for motorists traveling through mountainous regions to stay informed about local forecasts to mitigate the risk of being stranded in sudden snowstorms.
Travelers heading from Los Angeles to San Diego may encounter smooth conditions, but those venturing north to visit loved ones during the holiday season should be prepared for increasingly challenging weather near and above I-80. For an enhanced level of safety without interruptions from ads, consider upgrading to Premium+ on the AccuWeather app. By subscribing, you gain access to advanced, hyperlocal severe weather alerts that are activated by our team of expert meteorologists. These professionals work tirelessly to monitor and evaluate potential risks posed by severe weather conditions around the clock, ensuring the safety of you and your family.
