Moisture from Hurricane Rosa bringing high possibility of flooding to Southern Utah

Satellite image from NASA's Worldview shows Hurricane Rosa on its way toward landfall in Baja California, as of Sept. 28, 2018 | Image courtesy of the National Aeronautics and Space Administration, St. George News

ST. GEORGE — Southern Utah’s dry spell is expected to be washed away early next week when a hurricane hovering over the Pacific Ocean makes landfall.

Map shows the estimated arrival times of Hurricane Rosa as it inches toward Baja California. Image generated at 7:45 p.m. MDT, Sept. 28, 2018 | Image courtesy of the National Oceanic and Atmospheric Administration, St. George News

Currently listed as a category 3 hurricane by the National Oceanic and Atmospheric Administration, Hurricane Rosa is forecast to move inland over northern Baja California by Monday. Moisture associated with the storm is thereafter expected to spread northeast through parts of the Southwest U.S.

Southern Utah will see the potential for heavy rain as early as Monday, according to the National Weather Service, with rains becoming stronger and more widespread over the state Tuesday.

The rain brings the possibility of flash flooding, particularly over prone areas such as burn scars, slot canyons, normally dry washes and urban areas with poor drainage.

All of southwest Utah is subject to a flash flood watch in effect from Monday afternoon through late Tuesday night, including St. George, Cedar City and surrounding communities. Popular outdoor recreation areas are also affected, such as Zion National Park, Capitol Reef National Park and Glen Canyon National Recreation Area.

Statewide, there is the potential for debris flows originating from burn scars and ponding on roadways. Main river stems, such as the Virgin River, will likely experience high water flows. Travel may be impacted due to debris flows, and most unpaved surfaces will not be passable due to muddy conditions.

High water flows under a bridge on Fort Pierce Drive in St. George, Utah, Sept. 27, 2014 | File photo by Jenn Amico, St. George News

Regionally, the tropical moisture will also bring heavy rain and flood potential to northern Arizona and southern Nevada, where a flash flood watch also is in effect from Monday afternoon through late Tuesday night.

According to the National Weather Service, rainfall rates of 1 to 2 inches per hour could lead to extensive flash flooding in communities and recreation areas in the Arizona Strip and southern Clark County, Nevada, including through the Virgin River Gorge into the Beaver Dam/Littlefield area and Mesquite.

Although the storm system is expected to be strongest Monday and Tuesday, it is forecast to remain over the Southwest for much of the week.

The moisture will also usher in significantly cooler temperatures to Southern Utah, bringing an end to the dry heat that has triggered warnings about critical fire weather this weekend.

Read more: Southern Utah weekend weather: I’ve seen fire and I’ve seen rain…well, not yet

According to The Weather Channel, next week’s highs will be in the 70s in St. George and the 60s in Cedar City.

Update Sept. 29, 4:45 p.m. This report has been updated with information about a flash flood watch in effect for southwest Utah.

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1 Comment

  • DB September 29, 2018 at 4:43 pm

    There is a reference made to The Weather Channel. My opinion, they are a joke, though I’ll watch for a couple minutes each morning when I have nothing else to do. It is all about ratings and they are quite east-centric. They couldn’t care less about us in the west. Regarding hurricane Rosa, TWC opined on how the leftovers would affect the Midwest, completely ignoring anyone in between. Almost spilled my coffee as I was laughing so hard. I’m exaggerating but I could be flooded out before any of that moisture reaches the Midwest. When it reaches NYC, it will be ‘all hands on deck’ at TWC.

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