Tropical Storm Hilary Made Historic Trek Through Southern California, With Record Rain Into Nevada (RECAP)

H​urricane Hilary made a historic trek as a tropical storm into California and Nevada with record rainfall, flash flooding, rockslides and gusty winds.

H​ilary was born as a tropical storm on August 16 well off the coast of southwest Mexico. Its explosive, rapid intensification into a Category 4 hurricane in less than 48 hours was eye-popping.

But it was its unusual path into Southern California and soaking rain penetrating into the Great Basin that will be the ultimate legacy of this storm.

A first in California in decades: Hilary was the first Eastern Pacific system to still be categorized as a tropical storm while crossing into any part of California since Nora in 1997, nearly 26 years ago. B​ut 1997's Nora crossed into California near the border with Arizona.

A​fter first making landfall in Mexico's northern Baja California Peninsula, the center of Hilary then moved directly over Southern California, even over downtown L.A., on August 20. That was the first tropical storm to track over the L.A. Basin since 1939.

Prior to that, the National Hurricane Center and National Weather Service issued a tropical storm warning for Southern California for the first time.

(​MORE: California's Tropical Storm And Hurricane History)

C​alifornia rain records were smashed. Hilary, and the deep tropical moisture it tapped, wrung out prolific rainfall over much of the Mojave Desert and Southern California, particularly by August and summer dry season standards.

P​erhaps no rainfall record was more incredible than America's driest and hottest location, Death Valley. They not only smashed their calendar-day rainfall record set just the previous August, but they also picked up a year's worth of rain in just one day.

T​hat prompted a closure of Death Valley National Park, which stranded an estimated 400 people in the park due to flooded and/or damaged roads, according to an August 21 press release.

P​almdale, California (3.93 inches) also smashed its wettest day record that had stood since World War II.

N​umerous August rainfall records were set during Hilary, including downtown L.A. (2.48 inches), San Diego (1.82 inches) and Bakersfield (1.08 inches). These are rainfall totals from storms you'd expect in the heart of the state's wet season in winter, not in summer.

More than 2.25 inches of rain fell in just six hours on Sunday at the Palm Springs airport, which amounts to around 50% of the annual rainfall seen at the site.

T​his heavy rainfall lead to numerous road closures and a few washouts in the Mojave Desert and in parts of the mountains of the L.A. Basin due to flooding and/or landslides.

Great Basin was soaked, too. Hilary's remnant kept moving north and, together with a deep plume of moisture, parts of Nevada, Oregon, Idaho and Montana were also hit by heavy rainfall.

U​p to 9 inches of rain in the mountains west of Las Vegas triggered damaging flash flooding to roads and some structures in Kyle Canyon.

T​hat 9-inch rainfall total in Lee Canyon set a state record for any tropical cyclone or remnant, according to data compiled by David Roth of NOAA's Weather Prediction Center.

T​hat wasn't the only state to smash such a record.

S​oaking rain continued to stream north into parts of Oregon, Idaho and Montana, also setting records for a tropical cyclone remnant in each of those states.

A​tmospheric moisture ("precipitable water") values were the highest on record in Boise, Idaho, which also had a rare 1-inch August rain event from Hilary's remnant moisture.

S​everal locations in southeast Oregon and southwest Idaho had their wettest August day on record.

There were strong wind gusts, too. While Hilary was a tropical storm, it still produced several gusts over 60 mph in several locations in California and the West. Gusts up to 87 mph were clocked in the mountains north of L.A.

I​nstead of rain, Yuma, Arizona, clocked a gust to 69 mph, which whipped up blowing dust.

T​here were some other oddities with Hilary. As warm, tropical air surged north, downtown San Francisco surged to its hottest temperatures of the year at the time - 83 degrees - on August 20. They didn't pick up any rain from Hilary, however.

There was also the satellite imagery showing the bizarre juxtaposition of deep moisture associated with Hilary soaking the northern Great Basin while dense smoke from wildfires blanketed parts of western and northern Oregon into Washington state just a couple hundred miles away.

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