Flood watches, wind advisories issued throughout Utah ahead of Rachel's arrival

SALT LAKE CITY — It's unclear how structured Tropical Storm Rachel will be by the time the Pacific storm arrives in Utah, but federal meteorologists say it will still have enough power to create impacts throughout the state.

That's why the National Weather Service issued a series of flood watches and wind advisories across the state, noting that while 1-2 inches of rainfall is likely in most of Utah's valleys, 2-4 inches of rainfall is possible between late Saturday and Monday, with potentially even higher numbers in some mountain locations.

"Those living in areas prone to flooding should be prepared to take action should flooding develop," the advisories state.

Warnings are possible depending on where flooding develops.

Flash flooding is possible at Utah's state and national parks, monuments and other popular outdoor recreation areas across southern and central Utah on Saturday, but the risk is elevated from probable to expected on Sunday, especially in southwest Utah, per the weather service.

That risk could linger into early next week, although storms will become more scattered toward late Monday through potentially Wednesday.

The agency also issued a series of wind advisories, noting that gusts of 55-60 mph are possible at times before the former hurricane arrives. Those could be elevated to high wind warnings in central and southern Utah, with gusts potentially exceeding 60-70 mph.

A "sting jet" is also possible as the system passes through the southwest Utah's mountains and valleys on Sunday.

Rainfall deviations

There's still some uncertainty as to how much Rachel will provide, which depends on the track the storm takes as it moves through the West and many other variables, said KSL Weather meteorologist Devan Masciulli.

Weather models have gone back and forth over the last few days, showing the center of the storm moving through southwestern Utah or southeastern Nevada. That could impact who receives the rain circulating around it.

"It's a factor of where that circulation sets and where it passes through Utah," she said.

As long as the storm remains close to the Utah-Nevada border before jetting through Utah, it will likely produce strong precipitation.

However, how Rachel interacts with another low-pressure system moving across the Pacific Northwest toward California and eventually Utah will affect numbers since it will pass underneath the core of Rachel as it moves east.

That's on top of the normal elements that can affect Utah's precipitation totals, like mountains faring better than valleys and potential rain shadowing, Masciulli added.

KSL Weather models, updated Friday afternoon, suggest many communities across the state could receive 1 to 2 inches or more of precipitation by the end of Wednesday, taking into account the second storm.

Final totals could be higher or lower, depending on all these types of variables.

Totals could even exceed 4 inches in parts of the mountains. The weather service's alert notes there's even a potential for "highly localized amounts" of 6-8 inches of precipitation across some mountain slopes in southwest Utah, as well as the Book Cliffs and the Bear River Range.

Masciulli said south-facing slopes in those areas are the most likely to receive that type of precipitation, based on the storm rotation. West-facing slopes in northern Utah could also fare well.

"It's complex," she added, with a nervous chuckle.

Lesser totals are expected toward southeast Utah, based on the likely storm path.

Wind concerns

Federal meteorologists say there could be a risk of downed trees, especially in backcountry camping areas in central and southern Utah. That has happened in the past with previous hurricane remnant storms like this, the weather service noted.

The biggest wind risk comes from the threat of potential sting jets forming in southwest Utah. A sting jet is a "small area of very intense winds," which gets its name because it looks like a scorpion tail, as winds blow downward, according to the Met Office.

It's similar to downslope winds, Masciulli explained. Projected wind gusts of 70 mph or more are possible Sunday, which could last for a few hours.

"These are severe-level winds," she said. "When you add saturated soils and very strong wind like that, that's going to knock down trees and that can cause a bunch of issues, like injuries, power outages and damage."

Strong and severe thunderstorms are also possible on Sunday, with an "isolated tornado threat" across southern Utah, the weather service noted in a video report.

The risk for strong gusts is expected to eventually subside by Monday.

Full seven-day forecasts for areas across Utah can be found at the KSL Weather Center or on the KSL Weather app.

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