This unique event unleashed floods across Southern California, an area more accustomed to drought conditions, leaving officials and residents grappling with the aftermath and assessing the extent of the damage.
The National Weather Service eventually downgraded the storm from a hurricane to a tropical depression.
In response to the situation's severity, California Governor Gavin Newsom declared a state of emergency for much of Southern California. Flash flood warnings were in effect until the early hours of Monday.
Forecasters warned that mountain and desert regions could witness between 5 to 10 inches (12 to 25 cm) of rain – a significant amount for these arid areas, sometimes matching their annual rainfall in a single event.
Despite the downgrading, Los Angeles Mayor Karen Bass expressed concerns about the potential underestimation of the threat. She emphasised that vigilance was essential, as the storm's bands could unexpectedly return and catch unprepared individuals off guard. Bass underscored the need for people to stay home and prioritise their safety.
Hilary, the tropical storm, was projected to swiftly move across Nevada on Monday before dissipating later in the day. This storm originated in Mexico’s Baja California peninsula, where it caused fatalities, flash floods, and widespread road damage.
The storm crossed into the United States through the border, marking the first tropical storm to hit San Diego County and the first to affect Los Angeles County since 1939. Torrential rain, mudslides, rockfalls, and trees being swept away affected areas, particularly in San Bernardino County to the east of Los Angeles. Evacuations were ordered in mountainous and valley towns.
Ventura County, located northwest of Los Angeles, witnessed heavy rainfall and the National Weather Service issued warnings of potentially life-threatening flooding. Rainfall of up to 2 inches (5 cm) within two hours heightened concerns.
Recognising the gravity of the situation, U.S. President Joe Biden directed federal agencies to deploy personnel and supplies to the region. Los Angeles County’s sizable homeless population and vulnerable areas exposed by recent wildfires are of utmost concern.
As a precautionary measure, the two largest school districts in the state – Los Angeles and San Diego – cancelled school on Monday. The storm's impact left residents in awe, with reports of water and debris flooding roads and stranding vehicles.
Sean Julian, a resident of the affected area, expressed astonishment at the unprecedented event, highlighting the downed trees and significant tree falls. The storm's unpredictable nature underscored the need for caution and prudence during these extraordinary circumstances.