TL/DR –
California is experiencing a severe storm system that is causing heavy rain, wind, and lightning, with the worst expected in Southern California. The storm is linked to a strong El Niño, and is part of a series of possible storms that could affect the West Coast during the holiday season. Despite potential flood risks, the rain is seen as welcome due to a dry start to the water year, although the state’s snowpack is still only 33% of the average due to the warmth of the season’s storms so far.
California Braces for Intense Storm, Potential Flooding
A severe and slow-moving storm is expected to bring heavy rainfall, wind and lightning to a large part of California. The worst of the weather system is likely to hit Southern California from Wednesday through Friday, potentially causing travel issues and dangerous flash flooding before the Christmas holiday.
“This may have quite significant storm-related impacts in Southern California, including localized regions of very heavy rainfall and torrential thunderstorm downpours,” said Daniel Swain, a climate scientist at UCLA.
Weather Pattern Associated with Strong El Niño
This weather system is due to a large region of low pressure offshore, which is drawing moist, subtropical air over Southern California. It is part of a series of potential storms that could affect the West Coast during the holiday season and seems linked to a strong El Niño.
Flood watches cover most of coastal Central and Southern California until Friday afternoon. The National Weather Service warned of significant travel delays, road closures, creek flooding, potential swift-water rescues, and increased river flows.
Rainfall Predictions and Flooding Risks
Local reports show that some high terrain areas such as Santa Barbara, San Luis Obispo, and Ventura counties have already received inches of rain. Los Angeles has received around 0.1 to 0.25 inches so far, but forecasts predict 2 to 4 inches through Friday.
The National Weather Service in Los Angeles stated there is a “high risk of flooding just about anywhere, especially on the south-facing slopes from southern Santa Barbara County to LA County.” Four to eight inches of rain are expected in higher terrains, with some isolated areas potentially seeing up to 10 inches or more.
Stormy Weather Welcomed Despite Risks
Despite the flood risks, this wet weather is welcomed after the dry start to the water year in October. “We’re in this stormy pattern, so at least for now it looks like periods of unsettled weather are coming through,” Thompson said.
A strong jet stream could bring another round of storms to Central or Northern California next week, according to the Weather Service’s Climate Prediction Center. This storm track, indicative of a strong El Niño, raises the chances of a wet winter in Central and Southern California.
Concerns About California’s Snowpack
While snow is falling at higher elevations, California’s snowpack is currently only 33 percent of average due to the warm nature of the storms this season. “I would not be too surprised if Sierra Nevada snowpack as of Jan. 1 is alarmingly low,” Swain stated.
Although the Sierra Nevada saw significant snow accumulations last year, snowfall has been decreasing over the past decades due to climate change and is projected to continue decreasing, with more precipitation falling as rain.
“This is the kind of thing that we would expect to see … seasons that start dry and then get really wet, and perhaps a little too wet too quickly,” Swain said.
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