Flooding, dangerous surf forecast for California from Hurricane Kay

The remnants of Hurricane Kay are just a day away from bringing significant rainfall to parched regions of southern California and southwestern Arizona — but the downpours may end up being too good.

Forecasters say areas of flash flooding are likely in the area Friday through Sunday. Southern California’s interior mountains could see up to 5 inches of rain, an exceptional amount.

“Confidence remains high for a significant rainfall event in this region,” the National Weather Service said. said Thursday in an online discussion.

The remnants of the storm could also bring gusty winds and dangerous surf conditions to coastal areas of Southern California.

A Category 1 hurricane with winds of 85 mph, Kay is expected to make landfall on the west central coast of Baja California in Mexico Thursday evening. The storm is weakening and is expected to downgrade to a tropical storm on Friday.

blamed for at least three dead in Baja CaliforniaKay continues to be a major rain producer.

The storm is expected to bring 6 to 10 inches of rain across much of the peninsula, with localized amounts of up to 15 inches. Near the coast, Kay is expected to cause large waves and dangerous rip currents, with damaging storm surge, or a rise in ocean waters above normally dry land also possible.

Tropical storm warnings have been issued for the entire Baja California coastline, even on its eastern side, which rests on the Gulf of California. This is because Kay is a big hurricane; tropical storm-force winds (over 39 mph) extend up to 230 miles from its center, while hurricane-force winds (over 74 mph) extend up to 35 miles from the center.

Effects on the Southwestern United States

Kay is expected to weaken further and move away from the Mexican coast as it approaches very dry Southern California. Still, southwesterly winds will carry Kay’s moisture to the region, bringing with it first cloud cover that will help end the prolonged and record heat wave.

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The remnants of the hurricane will also carry unusual amounts of moisture that could help alleviate the ongoing drought in Southern California. Some thunderstorms associated with Kay have already started rumbling near Riverside, California, bringing heavy rain and isolated lightning.

Although rain is needed, the National Weather Service warns that Kay’s arrival will not be without danger.

“Despite these positives, it’s never a good thing to have too much rain at once, an all-too-common trait among slow-moving tropical storms,” ​​the weather service wrote.

Hurricanes move slower, making them even more dangerous

Precipitable water, a measure of atmospheric humidity, is expected to exceed 2 inches in parts of Southern California by the end of Friday. That’s five standard deviations above the norm for the region at this time of year, which means it’s very rare.

Flash floods are most likely in narrow slot canyons, in urbanized areas like San Diego, Palm Springs, California and Yuma, Arizona, and over burn scars, where fire has ripped away vegetation and water tends to drain quickly rather than soaking into the ground.

Flood Watches were hoisted from central Southern California to western Arizona, and the weather service placed a large swath of southern California and a growing portion of southwestern Arizona in the at-risk zone light to moderate flash flooding Friday through Saturday morning.

Rainfall amounts of more than 2 inches are likely in the area covered by the flood watch, with up to 4 or 5 inches possible on the eastern slopes of the mountains, where easterly winds will intensify precipitation.

In San Diego, an inch or less of rain is expected, mostly falling Friday through Saturday morning. But, being along the coast will bring a distinct set of dangers. The weather service warns of dangerous rip currents and high waves of 3 to 6 feet, as well as the possibility of gusty winds up to 40 miles per hour.

In Los Angeles, the Weather Service forecast 0.25 to 0.75 inches of rain, with 1 to 2 inches in the mountains to the east, mostly falling Friday evening through Saturday.

Some beneficial rain could reach as far north as the southern San Joaquin Valley before the precipitation gradually dissipates on Sunday.

Although Kay won’t be close to making landfall in California, it will still bring strong winds on Friday that will increase the local fire danger. Gusts over the Laguna Mountains east of San Diego could exceed 70 mph, which will help fuel the fires.

The thunderstorms could also bring dangerous cloud-to-ground lightning that could spark wildfires in the area – although any downpour from Kay could help nullify some of them.

Kay isn’t the first tropical system to affect California, but such occurrences in the state are fairly rare. They usually come from the remnants of tropical storms and hurricanes, as is the case with Kay, rather than direct strikes.

No named system has ever made landfall in California, although an unnamed storm in 1939 crossed the coast around Long Beach, bringing tropical storm conditions.

California’s most notable encounter with a tropical system probably occurred in 1976 when Tropical Storm Kathleen, previously an over-ocean hurricane, entered south-central California from Mexico. kathleen unleashed a maximum rainfall of almost 15 inches, a state record. The storm caused severe damage in Ocotillo, Calif., and blamed for 12 deaths in the USA.

Jason Samenow contributed to this report.

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