Flash flood warnings follow levee breach in Washington state

Dec 15 (Reuters) - A levee breach in Washington state following days of heavy rain has led to a flash flood warning and evacuation orders, authorities said on Monday.

The National Weather Service said it had issued a flash flood warning after a failure at the Desimone Levee in Tukwila along the Green River, about five miles south of downtown Seattle. The service said that waters were likely heading toward Interstate 405, a major roadway, and that an evacuation notice was in effect for a large chunk of King County where about 46,000 people live.

"Leave immediately if you are in this area," said a social media note from the service.

"Conditions are dangerous and access routes may be lost at any time," the NWS wrote.

The Washington National Guard said that it was sending Guard members to King County. The Guard has already been helping flood-impacted residents in the western part of the state over the weekend.

Authorities have been concerned about levee breaches for days around Washington state, as torrential downpours hit a wide swath of the Pacific Northwest.

The rains were spawned by a string of atmospheric river storms, vast airborne currents of dense moisture siphoned from the ocean, that swept inland over the Pacific Northwest, including parts of northern Idaho and western Montana, with upward of 20 inches of rain falling in some areas over the course of a week.