A low pressure system moving toward California is forecast to bring a broad swath of weather hazards to the region through Tuesday. Most notably, the path of the low as it moves toward San Francisco and then north up the West Coast will result in the cold front boundary and associated moisture plume being aimed toward Southern California.
The bulk of the moisture will aim around Santa Barbara and Los Angeles. In these locations, something like one half to two thirds of the annual average rainfall for these locations is expected.
Urban flooding in cities, landslides, and flash floods. Additionally, debris flows coming off recent burn scars are likely. Higher rainfall values are expected in the mountains.
With the atmospheric river being driven by the cold front, mid-altitude temperatures north of it will allow for dropping snow levels in the Sierra Nevada. The ECMWF shows about 40 inches (100 cm) of snow at Lake Tahoe through Tuesday.
As of February 3, California snowpack (which is largely focused on observations in the Sierra Nevada, Cascades, and Siskiyou Mountains) sits at 65% of the seasonal median for that date. Significant gains are expected as a result of this system but don’t expect the full deficit to be wiped out.
For the Bay Area, Sacramento, and North Coast, rain is forecast but won’t be as long lasting as down toward Los Angeles. The low pressure center will track close to the Northern California coast near peak intensity producing strong winds in the region.
Some coastal sites and mountains around the Bay Area will see wind gusts up to 60 mph (100 km/h). In the Central Valley, including Sacramento, there may be isolated gusts to 70 mph (110 km/h). Winds in the valley will be lighter in cities because of buildings and trees.
Beyond Tuesday, the moisture plume shifts south into Baja California but rain showers in Southern California taper off Wednesday with snow showers in the Sierra Nevada. Repeated (but lower) chances of rain continue toward the weekend.
The featured image is a scene from the excellent 1989 film UHF.
