Stormwatch: flash flood warning in effect

We just returned from Sierra Madre, where we encountered heavy rain, hail, thunder, and overflowing streets.  National Weather Service sent this out about 2 PM:

THE NATIONAL WEATHER SERVICE IN OXNARD HAS ISSUED A

* FLASH FLOOD WARNING FOR... SOUTH CENTRAL LOS ANGELES COUNTY IN SOUTHWEST CALIFORNIA... THIS INCLUDES THE CITIES OF...SIERRA MADRE...MONTEREY PARK... DOWNTOWN LOS ANGELES...LONG BEACH...

* UNTIL 600 PM PST

* AT 200 PM PST...VERY HEAVY RAIN WITH ISOLATED THUNDERSTORMS WERE IMPACTING THE AREA EXTENDING FROM THE LONG BEACH HARBOR NORTHWARD ACROSS DOWNTOWN TO THE FOOTHILLS OF THE SAN GABRIEL MOUNTAINS. STORMS OF THIS INTENSITY WILL CREATE FLASH FLOODING ACROSS MANY URBAN AREAS FOR THE NEXT FEW HOURS.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO DOWNEY... WHITTIER...PASADENA...

MONTEBELLO...GLENDALE AND EL MONTE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY. MOVE TO HIGHER GROUND.

NWS says that flash flooding remains a danger until midnight in the San Gabriel Valley, particularly below the burn areas.  We heard the fire department put on alert via the scanner about an hour ago, so don't travel if you don't have to!