This week San Francisco is experiencing what’s known as either an atmospheric river or, the term more common years ago – a Pineapple Express.
Both refer to the same meteorological phenomenon characterized, a storm with heavy rainfall that comes when a flow of warm, moist air flows from the Hawaiian Islands across the Pacific ocean to the west coast.
When it reaches the cooler air over the west landmass, the water vapor precipitates out, falling as a heavy rain. An atmospheric river formation can carry more water in it, as vapor, than the Amazon River.
Because the band of warm, moist air flows in a distinctive, narrow band, the phrase “atmospheric river” has become more common in the past few years.
For more information about atmospheric rivers,
Here are some photos taken around the neighborhood today. This weather isn’t done yet: Send us your dramatic images and we’ll post a follow up.
Meanwhile, be careful, stay safe, and —New Year’s Resolution—clear those gutters and storm drains!