In the past two weeks, San Diego County initiated two flood watch alerts due to the excess rainfall from severe winter storms. Now concluded, the two watches were in effect from 4 a.m. on Dec. 24 through 1 a.m. on Dec. 25, and from 6 a.m. on Wednesday, Dec. 31, to 5 p.m. on Friday, Jan. 2.
Flooding in San Diego is generally concentrated in Mission Valley, as excess rain causes the San Diego River near Fashion Valley shopping mall to overflow. The rainstorm raised the river’s water level from its average height of 2.5 feet to a high of 5.46 feet.
San Diego County uses the ALERT Flood Warning System to keep residents aware of potential flooding through phone notifications. A flood watch is initiated through the system when flash flooding may occur in a given area due to excessive rainfall. A flash flood warning advises residents to evacuate an area due to an ongoing or imminent flash flood. The ALERT system controls 100 flood warning stations, including rainfall sensors, weather stations, reservoir level sensors, and stream gages across San Diego.
The ALERT Flood Warning System advises residents to take precautionary measures to prevent injuries and damage to their property during floods. Placing sandbags around houses and other property helps redirect water and prevent soil erosion. It also advises individuals to get to the highest level of a building in case of rising floodwater.
San Diego County issued the first flood watch throughout the county in anticipation of a winter storm forecasted for Christmas Eve. On the week of Dec. 24, the first winter storm brought 45-mile-per-hour winds and a total of 0.8 inches of rain, causing difficult driving conditions, property damage, power outages, a number of injuries, and one fatal casualty.
San Diego County initiated its second second flood watch in anticipation of a stronger rainstorm that began on Tuesday, Dec. 30. The National Weather Service also issued a beach hazards statement for San Diego’s coastal areas, warning residents of high tides in La Jolla and local beach flooding until Monday, Jan. 5. This warning also indicated a flooding forecast in the river by Fashion Valley.
The second rainstorm brought 2.46 inches of rain to San Diego County from Dec. 31 to Thursday, Jan. 1, with winds reaching 40 miles per hour. The river by Fashion Valley rose to 12.75 feet, leading to minor flooding in the Mission Valley area and surrounding roads, including Qualcomm Way, Friars Road, Mission Gorge Road, and Camino del Este. The Mission Valley and Fashion Valley trolley stations were also impacted by water overflows and temporarily suspended transit operations.
San Diego Police Department and San Diego’s swiftwater rescue teams rescued individuals trapped in their submerged cars on Jan 1. Emergency crews urged residents to not attempt to drive while the roads were flooded to avoid more cars getting stuck. The flooding also caused damage to multiple properties in Mission Valley.
While the NWS forecasts a chance of rain throughout next week for San Diego County, as of Sunday, Jan. 4, it does not anticipate further flood warnings.