Weather experts disagree on how much Hurricane Hilary will impact Phoenix area

PHOENIX — The unusually powerful Pacific storm moving north Friday off Mexico’s coast will probably bring rain to metro Phoenix this weekend, but opinions are mixed on how hard it will hit the Valley.

The latest seven-day forecast includes the chance of monsoon activity daily in the Phoenix area. The probability of rain spikes as the remnant of Hurricane Hilary passes to the west, peaking at 70% Sunday night.

However, Isaac Smith, meteorologist with the National Weather Service in Phoenix, said the Valley will remain on the eastern edge of the impact.

“Overall rainfall amounts aren’t expected to be all that impressive across the Phoenix area,” he told KTAR News 92.3 FM on Friday morning.

“But if you look further west, that’s where you’ll see the greatest rainfall impacts. So we do have flood watches in effect west of Phoenix across southwest Arizona, extending out into California.”

How much rain will Phoenix get from Hurricane Hilary?

While the National Weather Service is expecting the Valley to get between a quarter-inch and half-inch of rain from the Pacific storm, local climate expert Randy Cerveny thinks it could be twice that much.

Strong to severe thunderstorms will be possible later this afternoon and evening across parts of south-central and southwest Arizona. Damaging wind gusts, blowing dust, and localized flooding will be the primary concerns. #azwx pic.twitter.com/Ev2DcJRpat

— NWS Phoenix (@NWSPhoenix) August 18, 2023

“It might be wishful thinking, but as I look at the weather maps, I’m tending to go a little bit more than that. I want to go a half an inch to an inch,” Cerveny, a professor of geographical sciences at Arizona State University, told KTAR News on Friday.

Cerveny noted that hurricanes rotate counterclockwise, which could widen the range of Hilary’s impact as the storm moves north.

“A lot of its moisture is actually being pushed to the northeast. That’s why I’m thinking that actually Arizona might get a little more rain than what has been forecast,” he said.

“It’s all not just going to follow the straight path of the hurricane. A lot of it is going to be pushed off towards the northeast and that’s us, that’s Arizona.”

Phoenix monsoon could use a boost

Depending on how Hilary behaves, the Valley could see its first sustained storms of the monsoon season this weekend.

So far, the region has received only occasional scattered showers.

Phoenix proper didn’t get its first official monsoon rainfall until Thursday night, when .02 inches was measured at Sky Harbor International Airport. The National Weather Service uses an airport weather station for the city’s official readings.

Status of Hurricane Hilary as of Friday morning

Hurricane Hilary grew to Category 4 strength Friday morning, with sustained winds near 145 mph.

The Mexican government said a weakened Hilary might skim a sparsely populated area on the western edge of the Baja peninsula early Sunday, and then perhaps hit a more heavily populated area of the coast Sunday night between the cities of Playas de Rosarito and Ensenada, in Baja California state.

While it's still dark over the west coast of North America, @NOAA's #GOESWest 🛰️ is keeping a close eye on powerful #HurricaneHilary, a Category 4 storm with sustained winds of 145 mph.

This GeoColor/#GLM composite imagery of #Hilary shows the distinct eye and frequent… https://t.co/Nw25SrIx3u pic.twitter.com/WTr3eAgbFI

— NOAA Satellites (@NOAASatellites) August 18, 2023

Hilary could still be at tropical storm strength (sustained winds of 39-73 mph) when it reaches the United States. Southern California hasn’t been hit by a tropical storm since Sept. 25, 1939, according to the National Weather Service.

The U.S. National Hurricane Center issued a tropical storm watch for Southern California for the first time ever.

KTAR News 92.3 FM’s Jim Cross and The Associated Press contributed to this report.

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