LOS ANGELES (KABC) -- Southern California's weeklong heat wave is finally waning now that Tropical Storm Kay has covered the region with clouds and rain, raising fears of possible flooding in mountain areas.
Saturday's forecast includes a 50% chance of showers, possible thunderstorms and winds of up to 25 mph with a flood watch that will be in effect through 11 p.m. in the Los Angeles County Mountains and Antelope Valley.
"Moisture from Kay will move into the area today (Friday) and linger through Saturday," according to the National Weather Service. "Showers and thunderstorms with periods of heavy rain at times will increase the risk of flooding, especially in the mountains. The heaviest rain is expected to occur late (Friday) through Saturday evening."
Forecasters said the rain could lead to excessive runoff resulting in "flooding of rivers, creeks, streams and other low-lying and flood-prone locations."
Kay had been categorized as a hurricane, but it weakened as it made landfall Thursday night, then began shifting to the northwest over the ocean. But Kay was still packing a punch, promising to bring widespread rain across the region.
"Rainfall amounts should generally range between a quarter to half inch for the coast, a third to two-thirds of an inch for the valleys, and a half to one-and-one-half for the mountains," according to the Weather Service.
"For the Antelope Valley, generally a third to two-thirds of an inch is expected for the storm. Locally higher amounts could develop, especially with any thunderstorms. Heavy downpours are possible across the mountains and desert where terrain will cause orographic effects that could increase rainfall rates."
The storm has already caused higher tides, prompting concerns of localized flooding along the coast. In Long Beach, crews worked overnight to fortify berms, and sandbags were being made available to residents to help protect their properties from flooding.
Long Beach fire and parks officials were focusing efforts in Alamitos Beach, building up protective berms mainly between Fifth and Ninth places.
"High tide for Long Beach will be at 9:16 p.m. tonight," the Long Beach Fire Department said on Twitter. "Please take efforts now to prepare your homes if you live in vulnerable locations along our coastline that are prone to flooding."
The Weather Service warned that Kay will bring steep seas and gusty east winds to coastal waters through Saturday.
Gale-force winds are expected at Catalina and San Nicolas Islands, with a chance of winds reaching 20 to 30 knots north to Point Conception and the Channel Islands.
Los Angeles County Supervisor Janice Hahn said sandbags were being made available to Catalina residents on the east side of South Beach. She noted that the storm "is forecasted to bring wind, high surf and coastal flooding to the island."
According to Hahn, Catalina Express canceled the 5:45 p.m. departure from San Pedro to Avalon, as well as the 7:40 p.m. boat from Avalon to San Pedro and the 9:45 p.m. departure from Avalon to Long Beach.