A powerful storm system is set to unleash heavy rainfall across Southern California, with San Diego County bracing for moderate to heavy downpours from mid-afternoon to midnight today, according to the National Weather Service. While not as severe as in neighboring Orange and Los Angeles counties, the rain has already caused some flooding in San Diego County.

The storm, fueled by an atmospheric river, has re-intensified after a brief slowdown. It is projected to deposit 3 to 4 inches of rain in North County by 10 p.m. Tuesday, with 2 to 3 inches expected in the city of San Diego and South County. So far, San Onofre has received 3.23 inches of precipitation, while Oceanside has recorded 1.48 inches.

The heavy rainfall has led to road closures in various parts of the county. Both eastbound and westbound lanes of state Route 78, between San Diego Zoo Safari Park and Bandy Canyon Road, have been shut down due to rain that fell on Sunday night and Monday. Additionally, the El Camino Real on-ramp to eastbound SR-78 has been closed. Mud in the roadway has forced the closure of a stretch of Ysabel Creek Road near Bandy Canyon Road, as reported by San Diego police.

The storm has also had an impact on recreational facilities, with SeaWorld San Diego opting to remain closed today for safety reasons.

Further north, in San Clemente, the storm has caused additional beach closures near a landslide site that disrupted rail service between the city and San Diego County earlier this year.

With the storm's core moving from southwest to northeast at a speed of approximately 30 mph, areas like Camp Pendleton, Oceanside, Fallbrook, and San Marcos are expected to face the brunt of the downpours. This could make travel difficult on major highways such as Interstate 5 and state Route 78, potentially causing commuting delays between San Diego and Orange counties.

The storm has two phases, with the first lasting until the early hours of Tuesday and the second wave expected to begin around noon on Tuesday, lasting into the night.

Given the forecasted heavy rains, a flood watch has been issued for the entire county and will remain in effect until 10 p.m. Tuesday.

Finally, the recent winter rains have made coastal cliffs in Del Mar increasingly susceptible to erosion and collapse.

As the storm progresses and the rainfall intensifies, residents in Southern California are urged to take precautions, monitor the weather updates, and stay safe during this severe weather event.