SAN FRANCISCO – After a relatively quiet week, the weather on the Pacific Coast comes back to life as a powerful storm system rotates off the coast, ready to bring a powerful atmospheric River Pineapple Express.
The storm threatens to have a multitude of impacts, including flash flooding, damaging winds, power outages and possible landslides.
A Pineapple Express is a weather phenomenon that brings lots of moisture from the tropical Pacific near Hawaii and hits the West Coast hard. This weather pattern can carry up to 27 times more water than the Mississippi River and typically features several inches of rain.
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Currently, rain is underway in the Pacific Northwest, but the worst impacts of the storm are still ahead as the storm moves south into California on Wednesday, the FOX Forecast Center said.
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Heavy rain spread across California Wednesday through Thursday
The main area of heavy rain will move towards the coast during the day on Wednesday, accompanied by strong winds.
“The Pacific Northwest has been hit the hardest by wet weather over the last couple of days,” said FOX meteorologist Jane Minar. “Now it’s finally moving down the coast. Not only are we talking about rain, but we also have wind warnings that are in effect for the West Coast, especially for the mountains.”
Strong winds may reach 60 to 70 mph along the southern Oregon and northern California coasts, with higher gusts in the mountains. Gusts could also reach 50 to 55 mph along coastal areas of the San Francisco Bay, with widespread gusts of 45 to 50 mph likely across a large swath of Northern California.
As a result, strong wind warnings were issued there. These winds can potentially bring down trees, leading to power outages. They will also cause numerous delays at San Francisco International Airport.
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Flood watches cover much of the northern and central California coast, including the San Francisco Bay area, through Friday morning, as heavy rain is expected to cause flooding of streets and small streams. Larger rivers may overflow their banks, also causing minor flooding.
The gradual nature of the rain, which will move relatively quickly to the south, will be a limiting factor in a greater risk of flooding with this storm, the FOX forecast center indicated.
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Rainfall in Northern California is expected to reach 2 to 3 inches, including the San Francisco Bay Area. The Coast Ranges may receive up to 4 to 6 inches of rain.
Forecast feet of snow for the Sierra Nevada
Heavy snow will begin Wednesday in the Sierra. Travel will be difficult, if not impossible, due to snow-covered roads and sometimes reduced visibility, with possible chain checks and road closures.
Snow can fall up to 2 inches per hour. Up to 4 feet of snow will fall at the highest elevations and snow could accumulate up to 3,500 feet, the FOX Forecast Center said. This will help a meager snowpack that is only 50% of average, but it will not completely erase the snow deficit.
Snow will also be a factor in the Southern California mountains. The cold nature of the system will allow snow levels to drop below 4,000 feet, the FOX Forecast Center adds. Those traveling along I-5 through the Grapevine area will need to take it slowly as snow levels will drop below 4,000 feet.
On the coast, large, powerful waves are expected to hit the coast from Oregon to southern California. High surf advisories are in effect for big waves, which could tear up popular beaches.
The National Weather Service (NWS) said surf heights from the southern Oregon coast to the San Francisco coast will range between 22 and 26 feet. Beaches in Los Angeles are expected to have waves of 8 to 12 feet, and beaches in San Diego will have waves of 10 feet.
Pineapple Express sets up shop in the Los Angeles area on Thursday
The storm is expected to move toward Southern California and the Los Angeles areas on Thursday, likely causing slowdowns during morning commutes.
The lowlands are expected to receive 1 to 2 inches of rain, while the surrounding mountains and hills could receive 2 to 5 inches. Rain is expected to cause flooding, leading to road closures and debris on mountain and canyon roads.
Residents of the San Diego metropolitan area, who were recently impacted by last Monday’s devastating flooding, will be particularly vulnerable. Fortunately, this storm isn’t expected to bring as much rain as that one, the FOX Forecast Center said.
The NWS warned of an increased risk of landslides in western Washington state due to heavy rains. Two landslides have already occurred, one in Seattle and the other at the foot of the Olympic Mountains.
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The main storm system will move over Thursday evening. As a result, widespread rain will be replaced by scattered showers and even a few thunderstorms, which will persist through Friday.
Second storm to hit Southern California could have bigger flood impacts
However, the stormy pattern will not end there. Another storm, perhaps more violent, is expected to hit Southern California starting Sunday.
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“(This storm) has an increasing potential for devastating flooding and is one of the most concerning (this week),” the Los Angeles NWS wrote.
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The FOX Forecast Center said early forecasts show this slow-moving storm could potentially bring several days of heavy rain to the region. Wider flooding and even heavier snowfall in the mountains are becoming increasingly likely.
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