Tornado warnings expire in Tooele County; flood risk continues in Utah

SALT LAKE CITY — A pair of tornado warnings for Tooele County have now expired, but storms continue to pass through the state that can be severe in nature.

The National Weather Service lowered its warning to a "severe wind threat" within a severe thunderstorm passing through the Tooele Valley Thursday evening. A severe thunderstorm warning for Tooele, Salt Lake and Utah counties also expired as the storm weakened while crossing the Oquirrh Mountains.

It wasn't immediately clear if any tornadoes formed, but Tooele, Dugway, Skull Valley, Stockon and Rush Valley were all included in or near a pair of warnings.

Radar imagery indicated the storm could produce hail up to 2-inch diameter as it passed north of Dugway, while one gust in the area registered at 93 mph. It then formed a rotation that often signals tornadic activity as it approached Rush Valley before it started losing its structure, KSL meteorologist Devan Masciulli explained.

The storm did disrupt some events as it moved through the region. Utah First Credit Union Amphitheatre was forced to evacuate due to lightning in the area, while the Banana Ball game between the Party Animals and the Firefighters was delayed.

It still kept plenty of rain even as it broke apart, dumping between 1.7 inches and 2 inches at sites in Sandy and Draper, which caused flooding in the area.

In Sandy, dozens of homes were flooded and basements flooded as well, said Rachael Van Cleave, Sandy City communications director. The water also caused some hydroplaning, with about 10 cars disabled during flooding.

Van Cleave said retention and detention ponds were doing their jobs by filling up with water. However, she wanted to warn residents that swimming in those ponds is not safe, and the water can contain pesticides, pet waste, and oil, while also being a drowning hazard.

The storm is from the same pattern that has created flooding concerns elsewhere in the state. Flash flood warnings were issued across multiple parts of southern Utah on Thursday, all of which have now expired.

Warnings were issued at Zion National Park in Springdale and Pine Valley in Washington County, as well as Capitol Reef National Park to the south and west of Caineville in Wayne County on Thursday.

The weather service issued a flood watch for many parts of southwest and central Utah earlier in the day, which now lasts through at least Friday evening. Utah's rivers, creeks and streams, as well as flood-prone locations like slot canyons and low-lying terrain, are typically the biggest risks.

Recent burn scars are also a risk. More than 500,000 acres have burned this year, adding to the list of prone areas. Residents are warned to move to higher ground immediately and avoid walking or driving through floodwaters if additional flooding forms.

The watch and warnings come as monsoonal moisture continues to move into the state, increasing the probabilities for showers and thunderstorms.

Scattered storms are expected across parts of the state through Thursday night and into most of Friday, which may be strong or severe in nature in some areas, Masciulli said. Friday's moisture will likely start in southern Utah and move to central Utah later in the day, with lower probabilities for the state's northern half.

While rare, Utah averages approximately two tornadoes every year. Thursday's tornado warnings came two days after the 27th anniversary of the tornado that ripped through Salt Lake City in 1999. Utah's last confirmed tornado came in April, touching down in Rich County.

It's even rarer for the National Weather Service's Salt Lake City office to issue a warning. It noted that its last warning came in September 2011, while its Grand Junction, Colorado office, which covers eastern Utah, issued five last year.

Flooding risks could last through Friday evening, before warmer and drier conditions are expected to develop by the weekend. Some storm activity may continue during the weekend, but it's more likely to be confined to the mountains.

Warmer and drier conditions are expected to linger into the start of next week. Full seven-day forecasts for areas across Utah can be found online at the KSL Weather Center.

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