Whether you call it an atmospheric river, a Pineapple Express, or just weather, many regions in California and the Pacific Northwest are forecasted to experience up to a foot of rainfall before the storm loses its intensity on Wednesday, according to weather predictions.

This wet weather marks a significant shift following a fairly dry January, which contributed to wildfires that ravaged thousands of homes in Southern California. The heavy rain will mainly impact northern and central California, where some areas may receive a month’s worth of rain within just a few days before the system fades away.

“The ongoing atmospheric river event is set to deliver moderate to heavy rainfall, posing a flood risk to northern and central California, alongside significant snowfall in the mountains,” cautioned the National Weather Service. They also noted that strong winds could lead to power outages and hazardous travel conditions in certain areas.

Atmospheric rivers are lengthy, narrow bands in the atmosphere that transport moisture from tropical regions near the equator towards the poles. A Pineapple Express specifically refers to an atmospheric river that begins near Hawaii.

“This Pineapple Express is notable for its length,” stated AccuWeather meteorologist Heather Zehr to YSL News. “It started affecting the coast on Thursday night, and the rain is accumulating fast.”

AccuWeather forecasts that a significant portion of northern California and southwestern Oregon will experience several inches of rain. They also warned of potential flooding, avalanches, strong winds, and travel delays. Cities in California, like San Francisco and Redding, are expected to receive a month’s worth of rainfall.

According to Zehr, landslides and mudslides could occur from the upper parts of California down to San Francisco, potentially causing road closures and travel interruptions.

Updates:

◾ Record-high temperatures are anticipated over parts of the Southwest extending into the Southern Plains through midweek.

◾ Arctic high pressures will move southward from Canada, affecting much of the northern United States early this week with temperatures significantly below average.

Heavy Rainfall Expected in a Short Time

The most intense rain, potentially exceeding a foot, from the Pineapple Express is predicted for Northwestern California and the northern Sierra Nevada. San Francisco, which typically averages 3.96 inches of rain in February, could see up to 4 inches. Redding, which sees an average of 5.48 inches this month, may receive between 4 to 8 inches by Wednesday, according to AccuWeather.

However, this storm isn’t expected to cause widespread damage as it moves inland, Zehr explained.

“This won’t push far inland,” she noted. “As it travels inland, it disconnects from its tropical source and the storm weakens significantly.”
 

Potential Hazards in the Eastern United States

A significant storm predicted for later this week could bring chaos to many areas in the eastern United States, according to AccuWeather meteorologists.

“An interaction of warm, humid air and frigid Arctic air will lead to various impactful weather events affecting millions this week,” stated AccuWeather Meteorologist Brandon Buckingham. “Severe thunderstorms, a potentially dangerous ice storm, and accumulating snowfall are anticipated between Wednesday and Thursday as the storm moves eastward.”