Pacific storms to pummel the West Coast, increase flood risk beyond Christmas
Multiple storms sweeping through the western United States into the last weekend of 2024 will bring a heightened risk of flash flooding, damaging winds and travel-snarling snow from Northern California to Washington, AccuWeather forecasters warn.
The wet pattern that got underway before the middle of the month has been marked by storms rolling ashore every 24 to 72 hours with a resurgence of rain and high-elevation snow. Early this week, the most recent storms to impact the region churned up seas so rough that part of the Santa Cruz Wharf in California collapsed into the ocean after being pummeled by high waves.
The additional bouts of stormy weather headed for the region may inflict further damage and compound delays for motorists and air passengers during one of the year's busiest travel times.
 |
"Some of the most impactful storms of this tumultuous stretch will hit the region during the latter half of the week," AccuWeather Senior Meteorologist Tyler Roys said.
Rainfall amounts of 4-8 inches can occur along the coast from northwestern California to Washington's Olympic Peninsula through Friday, with an AccuWeather Local StormMax™ of 16 inches.
"Since the ground is already soaked from prior storms, any additional rainfall through Friday will increase the threat for flooding and mudslides, especially across burn scar areas and along short-run rivers out of the Cascades," Roys said.
 |
Places along the Interstate 5 corridor from Seattle to Portland and Medford, Oregon, can expect the heaviest rain to arrive in two waves-one from Wednesday night into Thursday morning and another from Thursday night into Friday morning. Compared to the Christmas night storm, the second wave may aim farther to the south and bring soaking rain to the northern parts of the San Francisco Bay area.
"Unlike the storms prior to Christmas, the ones following the holiday are expected to bring stronger wind gusts, especially along the coast. Gusts can reach 80 mph at times along the coast from northwestern California through western Washington. The combination of these gusty winds, additional heavy rainfall and saturated ground will greatly increase the threat for power outages and downed trees," Roys said.
Snow levels across the Cascades and into the northern Rockies will vary with each passing storm into the weekend. This will lead to snow accumulations across many of the passes in Oregon and Washington and could result in closures for passes such as Scott Mountain Summit, Snoqualmie and Stevens. Up to 2 feet of snow is expected between Wednesday night and Friday.
"The varying freezing heights from storm to storm through the end of the week will result in an avalanche threat across the mountainous terrain, as rain can weigh down snow during milder periods of the storm, only to be refrozen and snowed on during times when snow levels drop. This melt and freeze pattern combined with water-loading the snowpack can yield a significant risk across the Cascades, northern Rockies and the northern Sierra Nevada," AccuWeather Meteorologist Brandon Buckingham said.
 |
The stormy pattern will continue this weekend, with milder air expected to move in and cause snow levels to rise. The combination of rain and snowmelt will further increase the risk of flooding at intermediate elevations.
"The parade of storms is not expected to stop this weekend, as more storms are expected through the start of 2025," Roys said.
Want next-level safety, ad-free? Unlock advanced, hyperlocal severe weather alerts when you subscribe to Premium+ on the AccuWeather app. AccuWeather Alerts™ are prompted by our expert meteorologists who monitor and analyze dangerous weather risks 24/7 to keep you and your family safer.
