SAN FRANCISCO – A powerful bomb cyclone is slamming the West Coast through Thursday.
The cyclone is pulling in a narrow but concentrated feed of tropical moisture, called an atmospheric river, which extends from Hawaii to California. This specific type of atmospheric river is known as the Pineapple Express as its moisture source originates near Hawaii.
The result of the atmospheric river will be intense lower-elevation rain and high-elevation snow that will fall across the entire state of California. This will be one of the most significant storms to impact the state in years.
Where is the California storm now?
Rain and snow are underway with the arrival of a well-defined warm front. The heaviest rain and greatest risk of dangerous flooding will continue Thursday as the trailing cold front and a coinciding plume of copious moisture continue to blast the region.
How many people are without power in California?
With very high winds, combined with the saturated soils, numerous downed trees are likely. Power outages had topped 180,000 in California Thursday morning, with the most widespread outages across northern and central portions of the state.
What are the active flood alerts for my area?
With soils saturated after 3 to 12 inches of rain over the past two weeks, the additional water has nowhere to go. As a result, numerous instances of flash flooding and mudslides are expected. Over half the state is under a Flood Watch.
Considerable and life-threatening flooding is especially possible along the Northern and Central California coast. Around recent burn scars, there is a considerable debris flow risk. Rivers across the state are forecast to rise into flood stage.
What are the active wind alerts for my area?
The powerful bomb cyclone will also cause very strong winds to sweep across California. High Wind warnings are in place as wind gusts could approach 60 to 70 mph.
As you can see from the map below, the reported wind gusts have been impressive across the state, topping 90 mph in some coastal and mountainous areas.
Will rainfall records be broken?
Widespread accumulations of 2 to 4 inches of rain are expected, with a high likelihood for totals approaching 10 inches in the higher terrain. While any rain is beneficial in California, this will likely come at a significant cost.
How much snow is expected?
Up in the mountains, dangerous travel conditions will continue through Thursday night.
Extremely heavy snow rates greater than 3 inches per hour are near certain above 5,000 feet in elevation. This will lead to dangerous, if not impossible, travel conditions.
An additional 1 to 4 feet of snow is expected across the Sierra Nevada. In Southern California, the highest peaks of the mountains will pick up 1 to 2 feet.
What's next for California after this storm?
There's no rest for the weary.
Another atmospheric river will blast the state this weekend and then yet another powerful one is likely next Tuesday and Wednesday. Each will bring a renewed round of dangerous flooding.
Over the next week, as much as 20 inches of rain may fall in the northern parts of the state from the combination of these multiple storm systems.