Atmospheric river brings ‘first’ hurricane warning to California: Live

The Grammys are set to take place in Los Angeles on Sunday night, during the time when the National Weather Service has warned of “heavy rain… with potential for damaging, life-threatening flooding”.

The worst of the incoming storm is forecasted to start at about 6pm PT on Sunday, with the Grammys scheduled to start an hour earlier.

Los Angeles is forecasted to get about three to six inches of rain while the foothills and lower mountains getting between six and 12 inches, meaning that there’s a severe risk of major flooding.

The Grammys will be hosted at the Crypto.com Arena in LA’s downtown.

Some counties in Northern California are seeing a small number of power outages, more of which are expected as the severe weather continues to batter the state.

Out of 14.8 million tracked customers – more than 21,000 have lost power so far – a number that’s likely to rise fast, according to poweroutage.us.

Those already affected include residents in Napa, California wine country, where almost 3,000 customers are without power, about 4.5 per cent of the tracked customers in the county.

An extreme flash food warning has been issued for Southern California, a rarity in the region, ahead of the arrival of the atmospheric river set to lead to several inches of rain.

On NOAA’s Flash Flood threat scale, the high-risk warning is the most severe and is only used for particularly foreboding forecasts, according to Fox Weather.

“The probabilities of 8-plus inches of rain in 24 hours are high enough to introduce a High Risk for portions of the Southern California Transverse ranges,” the National Weather Service (NWS) said. Parts of the mountains may see as much as 10 inches of rain.

“ALL AREAS, INCLUDING HIGHLY POPULATED URBAN AREAS, WILL BE AT RISK FOR LIFE-THREATENING FLOODING,” NWS Los Angeles wrote on Friday. “Streams and small rivers, as well as the Los Angeles River through the San Fernando Valley and metro LA will rise quickly and turn into very dangerous raging rivers. Many roads will be impassable due to flooding.”

The atmospheric river that will strike California on Saturday night is set to put the vast majority of the state’s population at risk.

“The greatest risk of a widespread flooding disaster is expected across the canyons and hills of Southern California, especially in Ventura, Santa Barbara and Los Angeles counties,” he added.

AccuWeather California Expert Ken Clark said: “The heaviest rain and greatest risk of dangerous conditions is likely along the east-west transverse mountains in the southern part of the state.”

“However, problematic heavy rain will fall throughout the Coast Ranges and the west-facing Sierra Nevada foothills below the snow level,” he added.

“Wind speeds in excess of 50 mph are expected over a wide area of the Golden State, especially in Central California. Winds over the higher terrain can gust to 70 mph,” he added.

When the moisture-laden air moves over mountain ranges such as the Sierra Nevada along the California-Nevada line, the water vapor rises and cools, becoming heavy precipitation that falls as rain or snow, according to NOAA.

While traditional cold winter storms out of the north Pacific build the Sierra snowpack, atmospheric rivers tend to be warm. Snow may still fall at the highest elevations but rain usually falls on the snowpack at lower elevations. That can quickly prompt melting, runoff and flooding and decrease the snowpack needed for California’s water supply.

Pineapple Express is a nickname for a strong atmospheric river in the tropical Pacific near Hawaii.

The incoming storm is unlikely to move on quickly after arriving.

“This time there’s going to be less movement, which means extreme rain totals,” she said.

The Los Angeles metro area may be hit by five or more inches between Sunday and the middle of next week.

“This is the type of rain that they cannot handle,” Ms Merwin said. “This is a guaranteed flood setup. There’s no way around it. We know it’s going to be bad, and there’s going to be huge impacts.”

“Everyone, especially those near or in south-facing mountains, needs to start preparing now for possible evacuations during or even before the storm hits,” NWS Los Angeles warned.