Bad storm news for the foothill communities

Three or four storms that could drop as much as 20 inches of rain on the San Gabriel Mountains foothills are expected to start rolling in this weekend. "This is their worst nightmare,” said Bill Patzert, the Jet Propulsion Laboratory climatologist who often cuts to the chase for local media. “It will be unrelenting.” County officials plan to close Angeles Forest Highway, Big Tujunga Canyon Road and Upper Tujunga Canyon Road from 4 a.m. Sunday through the storm series.

Here's how the National Weather Service sees things going, from a special weather statement this morning:

A major change in the upper level pattern is expected to begin on Sunday and continue through next week. A very powerful west to east jet stream sagging southward through the Pacific will break down the persistent ridge across the west coast. This will allow storm systems to track into Southern California while maintaining a rich source of subtropical moisture.

Confidence is growing that significant and possibly excessive rainfall will occur over southwestern California from Sunday through most of next week...but the exact details of timing are still unclear.

And the kicker for the foothills: "Local rainfall amounts over 20 inches wil be quite possible across favored south-facing coastal slopes." Threat of rock porridge: high.