Tropical Storm Rachel is pushing toward Southern California with the potential for life-threatening flash flooding, forcing residents across San Diego, Orange, Riverside and San Bernardino counties to prepare for rapidly deteriorating conditions.
The National Weather Service issued a stark warning Saturday, saying the storm could trigger widespread flooding, prompt evacuations, and wash out roads and bridges in parts of the region.
“Prepare for life-threatening rainfall flooding having possible extensive impacts across San Diego County,” the weather service said. “Major rainfall flooding may prompt many evacuations and rescues. Rivers and tributaries may rapidly overflow their banks in multiple places.”
Forecasters warned that flood water could enter homes and businesses in multiple communities, with some structures becoming uninhabitable or washed away entirely. Bridges and roads are also at risk of destruction from the deluge.
Rain bands had already begun moving into Orange and San Diego counties by late Saturday morning, according to Doppler radar, with the worst conditions expected to arrive Sunday.
How Much Rain and Wind to Expect
Coastal areas, valleys and deserts could see 1 to 2 inches of rain, while mountain areas may get as much as 2 to 4 inches. The National Weather Service said confidence is high that the heaviest rainfall will fall over the mountains and deserts of San Diego County, raising the risk of flash and urban flooding where rainfall rates peak.
Riverside and San Bernardino counties face a 40% chance of excessive rainfall capable of triggering flash floods in mountainous and desert areas, including Palm Springs, Joshua Tree National Park and Twentynine Palms.
Wind gusts of 39 to 73 mph are possible in some areas, strong enough to snap tree limbs, topple fences and road signs, and make driving hazardous on bridges and elevated roadways. Scattered power and communications outages are also possible. Sunday’s thunderstorms are expected to bring gusts of 20 to 45 mph in desert areas.
An Unusual Storm
Meteorologists say Rachel’s behavior is unusual, developing amid an emerging El Niño pattern and record-warm ocean temperatures off the California coast. UC Agriculture and Natural Resources climate scientist Daniel Swain called it “an unusual event that’s being made possible by both coincidence of this early arriving low-pressure trough off the coast of California and the record warm — and I do mean record warm — ocean temperatures off the coast of California right now,” during a briefing Friday.
Officials are urging residents across the four-county region to check emergency supplies, monitor weather alerts and local news closely, and be ready to evacuate if instructed. Drivers are being warned to avoid flooded roadways, since even shallow-looking water can hide dangerous currents or washed-out pavement.
