The caboose in the storm train and river of moisture that has been battering the western United States this week will deliver one final blow to California into Monday.
“Another moisture-laden storm system will slam into California early Sunday through Monday morning, bringing more heavy rain and mountain snow,” AccuWeather Meteorologist Jordan Root said.
Risk of flooding, wind damage and widespread travel disruptions to be renewed
Rain, wind and mountain snow will increase across northern and central California on Saturday night as the storm approaches. The wind-swept and heavy rain will then spread southward to Los Angeles and San Diego from Sunday into Sunday night.
An additional 3 to 6 inches of rain will inundate the lower foothills of the Sierra through Monday, while 1 to 3 inches falls from northwestern California to San Francisco, Los Angeles and San Diego with locally higher amounts, especially in upslope areas.
Root anticipates up to 4 inches of rain around Los Angeles. That follows the 2.49 inches Downtown Los Angeles recorded from Thursday to Friday.
“This round of rain combined with the previous storms will quickly renew flooding issues around Los Angeles,” he said.
Similar issues threaten to ensue across the rest of California, outside of the deserts, as the rain pours down on the saturated soil.
“Along with the threat of flash and urban flooding will be the high risk for additional mudslides and other debris flows in the canyons and mountainsides,” AccuWeather Senior Meteorologist Alex Sosnowski said. “Debris flows will not be limited to the recent wildfire areas.”
Streams and rivers in northern and central California should once again rise and could overflow their banks.
Strong winds accompanying the rain threaten to cause damage, power outages and could easily down trees sitting in the saturated soil or that have been weakened by previous storms.
The combination of the rain and wind can lead to flight delays and hazards for motorists. Downpours will reduce visibility and heighten the risk of vehicles hydroplaning at highway speeds. Dangerous crosswinds can overturn high-profile vehicles.
As the winds howl, dangerously rough surf will continue to pound the coastline. Minor coastal flooding, damage to piers and beach erosion could result.
Feet of snow to further bury the Sierra Nevada
In addition to the heavy rain, another long-duration snow event will further bury the mountains. Strong winds will lead to extensive blowing and drifting at times.
Such news is good for ski resorts and the region’s water supply heading into the warmer months. However, dangerous travel will result with likely road closures. This includes on I-80’s Donner Summit.
“The Sierras will likely see another few feet of snow through Monday,” Root said.
Plunging snow levels will cause rain to change to snow in the mountains of Southern California. A fresh 8 to 16 inches could fall at the ski resorts. Enough snow to cause slippery travel will coat the Grapevine section of I-5 later on Sunday night into Monday.
“There can even be a little snow that may impact travel through Cajon Pass,” Root said.
Disruptive snow will not just be confined to the mountains of California, but will spread to Reno, Nevada, and into the Rockies.
Major travel disruptions are anticipated along the I-40 corridor in the Flagstaff area, where additional snow totals may approach or exceed a foot.
A turn to quieter weather will then follow this major winter storm.
“There will be another storm system that will dive south near the coast of California [later on Monday into Tuesday], but this will be much weaker than the previous storms,” Root said.
Lighter periods of rain and mountain snow starting along the northern California coast will gradually diminish as the storm drops southward.
“High pressure will then build across the West towards the end of the week which will put an end to the storm train,” Root said.
However, there is concern for potentially damaging and disruptive Santa Ana winds to develop across Southern California toward and during next weekend.