Social Storm Origins: How long will it last and which areas will receive the heaviest rain?
The fast-moving Armorceric River is moving toward southern California this week and is bringing heavy rain, and with it, the risk of flooding and debris flows in newly burned areas.
The expected rain could also help reduce the risk of deadly fire season in the region this year.
The storm is expected to make landfall in northern California on Wednesday and reach Southern California on Thursday, according to the National Weather Service. The system could produce most of the rain the city of Los Angeles has seen for at least a month, and possibly as early as February.
When is the rain coming? How long will it last?
Thursday: The storm system is expected to reach Southern California on Thursday, dropping about 0.1 to 0.2 inches on La County per day. On Thursday night, the coast and valleys can get another 0.5 to 1.5 to 1.5 inches, with higher amounts of rain – between 1.25 to 1.75 inches – in the mountains and mountains.
Friday: Valleys and valleys may receive 0.5 to 1 inch of rain Friday night, coasts and valleys may receive 0.5 to 0.5 to 0.5 inches and 0.75 to 1 inch of rain.
Saturday: During the day, the coast and valleys are expected to receive 0.5 to 1 inch Saturday night, the coast and valleys may receive 0.1 inches of rain while the mountains may receive 0.15 inches.
Sunday: As the storm dissipates, most areas are expected to receive 0.1 inch or less.
In total, the system can place 2 to 2.35 centimeters
What are the risks?
Winds can be a problem, with peak gusts of 50 mph on the Grapevine portion of interstate 5 and in the Antelope Valley. The highway is an important transportation route for Cargo-carrying big rigs. Winds were gusting to 21 mph in downtown La, 23 mph in Long Beach, 25 mph in Santa Clarita, 30 mph in Redondo Beach and 44 mph in Lancaster.
Most areas will get about six to eight hours of rain, weather service officials in Oxnard said. Heavy rain could fall within three to three hours, at rates of up to three inches per hour. There is a 20% chance of rainfall amounts as high as 1 inch per hour.
The key threshold for rainfall rates that can cause significant debris flow is half an inch per hour or more.
The storm could also snarl traffic in Los Angeles and Ventura Counties, where rain is expected Thursday afternoon and evening, bringing puddles of water to roads. The LA Metro area could be heavy through Thursday evening, with localized flooding in low-lying areas, forecasters warned.
What does fire season mean?
The upcoming storm could have a positive impact on California’s fire season “If we get the kind of storm rates we’re expecting,” according to David Gomberg, NWS fire program manager.
It will take a few weeks after the storm to test how vegetation responds, he said, but the expected rain “should start to make a big difference in fire season.”
Officials generally like to see 3 to 4 inches of rain in the higher elevations to end the fire season. Downtown already received 1.38 inches in Oct. 14
