Kay continues to threaten flooding rain for SoCal

A serious flooding threat has developed across the bone-dry southwestern United States due to a substantial influx of moisture from Tropical Rainstorm Kay, located in the East Pacific near the coast of Baja California, Mexico.

Some of the worst flooding occurred in Southern California, and while Kay did not make landfall in the U.S., it will still made an unusually close approach to the Golden State and provide some needed relief from the recent extreme heat wave.

As of Saturday morning, Kay had lost wind intensity as it meandered westward offshore, and was expected to continue losing tropical characteristics over the coming days. By the end of the day Monday, Kay is expected to dissipate entirely.

The center of Kay made landfall as a Category 1 hurricane near Bahia Asuncion in Baja California, Mexico, on Thursday afternoon, according to the National Hurricane Center. Kay became a tropical storm just hours later, and was downgraded to a tropical rainstorm late Friday night.

As Kay continues to churn offshore, unsettled weather is likely to continue across much of the Southwest.

On Thursday, some outer bands from Kay were already sweeping across southern portions of the Golden State. As Kay continues to move northward, rain is likely to become more widespread.

Tropical moisture will help to bring thunderstorms as far inland as central Arizona and southern Nevada, impacting cities such as Phoenix and Las Vegas. However, the heaviest rain is likely to remain in Southern California, especially in mountainous areas.

The last named tropical system that came close to San Diego was Hurricane Nora from September 1997. Nora made landfall as a tropical storm on the Baja Peninsula of Mexico and continued to move northeastward, with the center of the storm moving into southwestern Arizona.

In total for the entire storm, widespread rainfall amounts of 1-2 inches of rain are expected across Southern California, including in cities such as San Diego and Los Angeles. Both cities, and many others across the area, average less than a quarter of an inch of rain over the entire month of September.

Rainfall amounts of 2-4 inches will be common in the mountains of Southern California, but some localized amounts as high as 8 inches will be possible. Already, several locations at high elevations east of San Diego have reported over 5 inches of rain, and additional rounds are expected through the weekend. While this additional rain will not be as steady as it was on Friday, rainfall totals will be able to sharply increase over a small period of time. An AccuWeather StormMax™ of 10 inches is forecast in some very localized areas.

Due to the potential for flash flooding, Kay has been rated as a 1 on the AccuWeather RealImpact™ Scale for Hurricanes in the U.S.

The strongest wind gusts in the United States from Kay are also expected to be in the higher elevations of Southern California. Wind gusts of 40-60 mph will be possible, especially in the mountains, AccuWeather forecasters say.

The thunderstorms and gusty winds pushing into the region could bring additional risks.

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More than 97 percent of the state of California is experiencing moderate drought conditions or worse. according to the latest update by the U.S. Drought Monitor. The addition of strong winds can fan any ongoing wildfires or any new fires that spark.

The wave of wet weather and increased moisture should eventually bring some relief to drought and assist with wildfire efforts. The Hemet, California area, which is about two hours east of Los Angeles and where the Fairview Fire has been burning since earlier this week, is forecast to receive more rain on Saturday. The fire is now 40% contained, and containment is likely to increase quickly over the coming days.

The wet weather from Kay also comes on the heels of an unprecedented heat wave. Extreme temperatures across the southwestern U.S. crushed long-standing records and incited record-setting energy demand in California.

Kay strengthened to a Category 1 hurricane (minimum sustained winds of 74 mph) on Monday as it paralleled the Baja California Peninsula of Mexico. Portions of the peninsula were being hit with heavy, tropical rainfall through the middle of the week.

Maintaining its intensity, the storm made landfall as a Category 1 hurricane near Bahia Asuncion, on Thursday afternoon, local time, with maximum sustained winds of 75 mph. As Kay re-emerged over the waters of the Pacific, interaction lead to a loss of wind intensity and Kay was downgraded to a tropical storm early Thursday evening.

The Baja California Sur government told AP that more than 1,600 people were evacuated to shelters prior to Kay's arrival. There were no reports of injuries, but rising waters and landslides made some roads impassable.

"Kay is a large storm. Continued interaction with land and northward track into cooler waters will cause Kay to gradually lose wind intensity over the coming days," said Buckingham. Despite this, wind gusts of as much as 60 mph can extend northward to the Mexico-California border.

This water vapor satellite image shows Kay bringing rain to Mexico's Baja California Peninsula on Thursday, Sept. 8, 2022.

Flooding rainfall will deluge continue the peninsula through Saturday, with widespread rainfall amounts of 2-4 inches. Locations between the towns of Loreto to San Felipe could see as much as 8-16 inches of rain. The higher elevations may be most susceptible to the higher rainfall totals, including the AccuWeather Local StormMax™ of 20 inches (500 mm).

Due to the flooding rainfall and gusty winds, Kay is a 2 on the AccuWeather RealImpact™ Scale for Hurricanes in Mexico.

Weather conditions began to improve in Baja California Sur early Friday, but it won't be until Kay starts to turn westward late in the weekend that much of Baja California will begin to experience lesser impacts from Kay. Dangerous seas and rip currents are likely to persist for western-facing shores into early next week

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