'Pineapple Express' storm douses California with rain, snow

   The weather system, also known as an atmospheric river, gets its name from the flow of moisture that periodically heads east from waters adjacent to the Hawaiian Islands to soak the US West Coast.
The weather system, also known as an atmospheric river, gets its name from the flow of moisture that periodically heads east from waters adjacent to the Hawaiian Islands to soak the US West Coast.PHOTO: TWITTER/NWSLOSANGELES

LOS ANGELES (REUTERS) - A Pacific storm system known as the "Pineapple Express" threatened to dump up to 20cm of rain and 2.44m of snow on areas of California, raising risks of flooding and mudslides, meteorologists said on Wednesday (Feb 13).

"The (Pineapple) Express is no joke," said Mr Bob Oravec, meteorologist with the National Weather Service's Weather Prediction Centre in College Park, Maryland, of the strongest weather system of the season.

The weather system, also known as an atmospheric river, gets its name from the flow of moisture that periodically heads east from waters adjacent to the Hawaiian Islands to soak the US West Coast.

It blanketed parts of Hawaii with snow over the weekend and is expected to drench California.

The San Francisco Bay area could be hit by flash flooding and falling trees as saturated ground gets up to 20cm more rain and strong winds blow in, the weather service said.

"We're talking 3 to 5 inches (7.62cm to 12.7cm) of rain in San Francisco and coastal areas in just the next 24 hours, and more on into Friday," Mr Oravec said.

To the north-east in the Sierra Nevada Mountains, passes could see between 2m to 2.54m of snow through Friday.

Valley areas face flood watches over fears the relatively warm Pineapple Express system could initially drench areas as high as Lake Tahoe with rain, melting snow and swelling rivers.

WILDFIRE BURN AREAS

The Central and Southern California coast can expect flash flooding and possible mudslides near recent wildfire burn areas, the NWS reported.

Mr Oravec said that the problem is not just the amount of rain, but the fact that it will hit in a short amount of time.

"It's going to be heavy and fast," he said. "Debris flows and mud slides are a risk in any area scorched by the wildfires. There's little to no vegetation to slow that water down."

Up to 5cm of rain was expected in the Los Angeles area between Tuesday evening and Thursday morning, the weather service said.

A string of winter storms has swelled snowpack in California to above-average levels, delighting farmers in need of water and skiers in search of powder.