SEATTLE — The Pacific Northwest and Northern California are preparing for one of the most powerful storms of the season, bringing heavy rain and strong winds that could lead to widespread power outages and flash flooding.
The Weather Prediction Center has warned of excessive rainfall risks starting Tuesday and continuing through Friday, as an intense atmospheric river — described as long streams of moisture extending far over the Pacific Ocean — approaches the region. Meteorologist Richard Bann from the National Weather Service highlighted that this storm system has escalated rapidly, classifying it as a “bomb cyclone.”
Areas expected to receive the heaviest rainfall extend from southern Portland, Oregon, to northern San Francisco, California, as this massive plume of moisture arrives. Bann cautioned, “Be mindful of the potential for flash flooding at lower elevations and winter storms in higher elevations. This event is likely to be significant.”
Northern California has already issued flood and high wind watches starting Tuesday, with forecasts predicting as much as 8 inches (20 cm) of rain for certain regions such as the San Francisco Bay Area, North Coast, and Sacramento Valley.
Additionally, a winter storm watch is in place for the northern Sierra Nevada above 3,500 feet (1,066 meters), where there is a possibility of up to 15 inches (28 cm) of snow over the next two days. Forecasters noted that mountain areas could experience wind gusts exceeding 75 mph (120 kph).
The National Weather Service’s Weather Prediction Center warned that “numerous flash floods, hazardous travel conditions, power outages, and tree damage can be anticipated as the storm reaches its peak intensity on Wednesday.”
Conversely, Southern California will experience dry conditions this week, coupled with gusty Santa Ana winds, which could elevate the wildfire risk in areas still recovering from a significant blaze that destroyed 240 structures. The Mountain Fire, which ignited on November 6 in Ventura County northwest of Los Angeles, was reported to be about 98% contained by Monday.
By week’s end, wind conditions are expected to subside in Southern California, with potential rain arriving in the greater Los Angeles area.
In southwestern Oregon, rainfall predictions are between 4 to 7 inches (10 to 18 centimeters), with the possibility of reaching up to 10 inches (25 centimeters) in certain locations by late Thursday night or early Friday morning, according to Bann.
A high wind warning will take effect for the north and central Oregon coast starting at 4 p.m. Tuesday, forecasting south winds of 25 to 40 mph (40 to 64 kph), with gusts reaching up to 60 mph (97 kph). Beaches and headlands could experience gusts up to 70 mph (113 kph), which pose a risk of widespread power outages due to falling trees and power lines. Travel in the area may also become challenging.
Washington State may also experience significant rainfall, but it is expected to be less severe than in Oregon and California. From Monday evening through Tuesday, certain coastal regions could receive up to an inch and a half of rain, according to Bann’s updates.
The National Weather Service has issued a high wind warning for coastal areas of Pacific County in southwest Washington from Tuesday afternoon to early Wednesday, as gusts could exceed 35 mph and be even stronger near beaches and headlands, posing a threat to trees and power lines.
Local Washington State Patrol Trooper John Dattilo advised drivers on social media to prepare for “some bad weather” on Tuesday evening, urging people to avoid road travel if possible.
Furthermore, a blizzard warning has been announced for much of the Cascades in Washington, including areas surrounding Mount Rainier National Park, beginning Tuesday afternoon with forecasts of up to a foot of snow and gusts of wind reaching 60 mph (97 kph). This may lead to difficult or even impossible travel across mountain passes.
Elsewhere, areas along the central and eastern Gulf Coast, including the Florida Panhandle, face flooding risks on Tuesday, with rainfall forecasts of 2 to 3 inches (5 to 7.6 centimeters), which could result in flash floods in low-lying and urban locales.
