An intense mid-latitude cyclone is expected to target the west coast of the United States early this week, sending a strong atmospheric river into Oregon and California. This low-pressure system is likely to undergo bombogenesis, or “bombarding out,” a term reserved for low-pressure systems that are rapidly intensifying, typically with a pressure drop of at least 24 mb in 24 hours. This definition changes based on latitude.

The storm system moving west Tuesday through Thursday has the potential to more than double that pressure drop, with forecast models showing a 50-60 mb drop in less than a day, starting at over 1000 mb Monday evening, and possibly drop below 950 mb by Tuesday evening. This intense storm system is expected to have major impacts on areas of northwest and northern California, bringing heavy rain, high winds and large swells.

As the low-pressure system develops, it will tap into a flow of subtropical moisture, creating what is known as an atmospheric river. These systems can cause extreme precipitation and gusts of wind.

The University of California San Diego has created a scale to help understand and prepare for the impacts of these systems, which ranges from 1 to 5. Some areas along the California coast could see Level 4 impacts, which falls into the ‘extreme’ category.

Very heavy precipitation is expected to fall Tuesday through Thursday, with precipitation totals possibly exceeding a foot or more in Southern Oregon and Northern California. Flooding in these areas is likely, including river flooding and flash flooding.

If you live in a low-lying area prone to flooding, be prepared to leave in case flash flood warnings are issued. Areas along the coast could also experience strong enough winds to down trees and power lines, especially Tuesday through Wednesday.

Check back with WeatherNation on air and online for updates on this impactful storm system.