Bomb Cyclone to Impact Pacific Northwest and Northern California

A powerful storm system, referred to as a “bomb cyclone,” is expected to bring severe weather to the Pacific Northwest and northern California starting tonight, with the potential for life-threatening conditions. The National Weather Service (NWS) has issued warnings for heavy rain, strong winds, and snow, as the storm intensifies and moves toward the region. The bomb cyclone is predicted to arrive in the Pacific Northwest by Tuesday evening, with wind gusts ranging from 60 to 70 mph across northern California to western Washington. As the storm moves in, the region began experiencing heavy rainfall on Tuesday afternoon, which will continue through Friday. Some areas, particularly between northern California and southwestern Oregon, could see more than 10 inches of rain, with flash flooding likely in vulnerable areas.

In addition to the torrential downpours, the storm is expected to bring blizzard-like conditions to parts of the Cascades and northern Sierra Nevada. Heavy snow and strong winds will likely create whiteout conditions, making travel nearly impossible in some mountainous regions. The NWS has issued flood watches in California’s Sonoma, Napa, and Marin counties, which will remain in effect until 4 a.m. Saturday. These areas could see significant flooding due to the intense rainfall. In western Washington, the NWS warned of gusty winds that will persist through Wednesday morning, possibly causing widespread power outages, road closures, and damage to temporary structures. The NWS has highlighted the potential for damage to buildings and infrastructure, and advised residents to be prepared for these impacts. With conditions expected to worsen through the middle of the week, residents are urged to stay vigilant.

The term “bomb cyclone” is used to describe a type of storm that undergoes a process known as bombogenesis. Bombogenesis occurs when a low-pressure system experiences a rapid drop in pressure of at least 24 millibars within a 24-hour period. This significant drop in pressure signals an intensification of the storm, which can lead to dangerous weather conditions, including high winds, heavy precipitation, and extreme temperatures. According to the NWS in Medford, Oregon, storms of this magnitude typically occur only about once every ten years, making this week’s bomb cyclone a rare event. The NWS predicts that this storm will produce some of the strongest winds seen in several years, with gusts reaching speeds that could cause significant damage.

In recent years, bomb cyclones have become more common, with notable instances in 2018, 2022, and just last month, when Hurricane Milton formed as a bomb cyclone. These storms have become a frequent concern for coastal regions, and they often bring intense weather systems that can have wide-ranging impacts across several states. The strength of this storm system is remarkable. The NWS expects the system’s minimum pressure to fall to 943 millibars by Tuesday evening. For comparison, pressures of this level are typically seen in major hurricanes, which are among the most powerful weather systems on Earth. Low pressure is a key indicator of storm intensity, and the lower the pressure, the stronger the storm becomes. This bomb cyclone is shaping up to be an extremely powerful system, comparable in strength to the most intense hurricanes that frequently impact coastal areas.

Residents in the affected areas are urged to take several precautions to prepare for the bomb cyclone. The NWS recommends securing any loose outdoor items, trimming branches that may be in danger of falling near homes, and ensuring that homes are ready for potential power outages. Since high winds and heavy precipitation are likely, the risk of downed power lines and trees is high, which could leave people without electricity for extended periods. Ready.gov, a government preparedness website, offers additional advice for those who may experience power outages. It is important to use generators only outdoors and away from windows to avoid carbon monoxide poisoning. Gas stoves or ovens should not be used to heat homes, as these can also pose serious health risks. Additionally, residents are encouraged to plan for alternative power sources in case of an outage, especially if the storm disrupts access to electricity for an extended period.

The storm’s high winds and potential for significant disruption have already caused some closures in the region. Bellevue College has canceled classes, events, and services due to the expected impact of the storm. Similarly, the Lake Washington Institute of Technology’s campus has been closed in anticipation of severe weather. As the storm continues to strengthen, more closures and cancellations are likely across the Pacific Northwest and northern California. These disruptions will affect not only educational institutions but also businesses and government services that may not be able to operate in the face of extreme weather conditions.

This bomb cyclone is part of a larger seasonal weather pattern predicted by the NWS. In its forecast from last month, the NWS anticipated that northern California and the Pacific Northwest would experience temperatures similar to those of last year between November and January. The region was also expected to see above-average precipitation, which may help to replenish water supplies but also increases the risk of flooding in some areas. However, climate scientists are predicting a 57% chance that La Niña—a weather phenomenon marked by cooler-than-average sea-surface temperatures in the eastern Pacific Ocean—could make a return late this year. La Niña is typically linked to drier winters in the western U.S., and if it materializes, it could reduce precipitation levels, impacting water availability and agricultural production in the region.

As the bomb cyclone intensifies and makes its way toward the Pacific Northwest and northern California, residents should be prepared for extreme weather conditions, including heavy rain, high winds, snow, and the possibility of power outages and flooding. The NWS has issued numerous warnings for the affected areas, advising residents to take necessary precautions and stay informed about the storm’s progress. While bomb cyclones are rare, their impact can be catastrophic, and this week’s storm is shaping up to be one of the strongest in recent years.