LOS Angeles Rain has deluged California this week, raising the risk of severe flash flooding in Los Angeles and San Diego until at least Thursday.
On Wednesday, the heaviest rain will target the Central Coast region, increasing the threat of flash flooding from Monterey to Los Angeles.
The strong upper-level low-pressure system will move southeastward just offshore the California coast through Wednesday night, bringing a steady plume of moisture from the southwest.
The most recent computer model guidance shows 2-4 inches of rain falling in just 24 hours across the Central and Southern California coastal areas, particularly in the Transverse Ranges, where rainfall rates may reach 0.75–1 inch per hour at times.
This amount of rain and the expected high rainfall rates may cause scattered flash flooding, some of which may be locally significant for the Transverse Range areas due to the effects of the higher terrain, according to the FOX Forecast Center.
The Weather Prediction Center (WPC) of NOAA has designated an area in Southern California as having a Level 3 out of 4 risk of flash flooding on Wednesday. The WPC warns that rain will be locally heavy at times, enhancing the chance for mudslides and flooding.
Flood risk targets Los Angeles and San Diego on Thursday
The conditions could worsen on Thursday as the plume of moisture shifts a bit farther south into Southern California.
The overall rainfall amounts combined with the potential for bursts of thunderstorm-triggered heavier rain, especially over recent wildfire burn-scar areas, have prompted the WPC to put much of Southern California at a Level 3 out of 4 risk of flash flooding.
At times, some instability will develop in the atmosphere, leading to locally higher rainfall rates. This could even result in a few rumbles of thunder, even in Los Angeles.
In the 48 hours ending Friday morning, between 5 and 8 inches of rain are expected to fall in several areas, with some places experiencing even higher amounts. This could result in significant flooding, including flash flooding and urban flooding. There’s also a chance of debris and mud flows in terrain areas or overburn scars, such as the South Fire burn scar in Ventura County.
Rain pushes inland Friday
The storm lingers into Friday before finally pushing inland late Friday near the Mexico border and heading into the Desert Southwest. However, long-range forecasts indicate additional rain is likely in California next week.
Snow blankets the Sierra Nevada
The same system is also dropping heavy snow over the highest elevations of California’s Sierra Nevada Mountains, with lower snow over the highest elevations of the Washington and Oregon Cascades and parts of Idaho and Nevada.
