Flash flooding caused roads within the park to close for several days.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SLC wrote it up.
Flash flooding caused roads within the park to close for several days.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Salt Lake City, UT wrote its last area forecast discussion before the first event at Aug 11, 3:25 AM MST, 10 hours 55 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 425 AM MDT Fri Aug 11 2023 .SYNOPSIS...Moisture expected to largely remain in place across the region into the weekend. This will result in isolated to scattered precipitation chances across much of the area, generally during the afternoon and evening hours. Northern Utah will gradually trend drier for the coming week while moisture remains in place across the south. && .SHORT TERM (THROUGH 12Z SUNDAY)...High pressure is starting to rebound over Utah and the Four Corners area this morning. Meanwhile, a closed low has settled over the California coast. A southwesterly flow aloft has returned to southern/central Utah, allowing moisture to continue to spread farther north. Latest PWAT analysis shows between 0.6-0.8 inches across the bulk of the state, with up to 1 inch across the far southwest corner. While northern Utah will see increased moisture compared to yesterday, the moisture has decreased slightly across the south. Expect increased chances/coverage of convection across northern Utah today in conjunction with the increase in moisture, while scattered showers and thunderstorms continue across the south. However, unlike yesterday, large-scale forcing is largely absent, other than a weak deformation axis across the GSL deserts across to the Uintas. Expect this to serve as a bit of a focus for convection, otherwise the bulk of convective initiation will be associated with the higher terrain. As such, the potential for flash flooding will be greatest for those areas downstream (east) of the spine of Utah, such as Capitol Reef and the San Rafael Swell. Otherwise, the only other real concern today will be gusty outflow winds, especially across northern and portions of central Utah. Southerly flow across southern Utah tonight into tomorrow will continue to bring increased moisture to southern Utah. However, the next shortwave trough to come through the PacNW will flatten the ridge again, keeping this moisture from spreading northward. Expect southern Utah to see increased coverage of showers and thunderstorms again tomorrow, while little day-to-day changes are expected across the north. The ridge will be replaced by more of a cyclonic flow over northern Utah by tomorrow night as the aforementioned trough strengthens over northern Plains, which should then allow the airmass over northern Utah to gradually trend drier heading into the coming week. .LONG TERM (After 12Z Sunday)...A rex blocking pattern off the west coast will persist through the long term with high pressure to the north of a cutoff low. Additionally, a ridge over the southern plains will inch closer to the four corners region. Overall, this will keep our weather pattern pretty consistent over the next week with temperatures near normal and diurnal convection, primarily over southern Utah where higher moisture content will be located. This consistency is reflected in the ensemble clusters with nearly 100% of ensemble members representing the same persistent pattern. It's not until the very end of the period that the members start to diverge slightly with 30% of members bringing the ridge axis over our CWA, and the remaining 70% of members keeping the ridge over the southern plains. && .AVIATION...KSLC...VFR conditions will persist throughout the period for the KSLC terminal. Mostly clear skies in the morning will give way to TCU in the afternoon with ~15% chance of thunderstorms. Transitioning to a northerly lake breeze will be delayed a few hours until the afternoon. Outflow from surrounding storms could create variable winds gusts. .REST OF UTAH AND SOUTHWEST WYOMING...Mainly VFR conditions will persist throughout the period with the exception of brief category reductions with isolated afternoon thunderstorms. Storms will be focused across most of the area except for far northern Utah with lower chances in the lower elevations (~15%) and higher in the terrain (~40% chance). Skies will be mostly clear with TCU building in the afternoon and CIGs between 10kft-20kft. && .FIRE WEATHER...Moisture will continue to overspread the state, resulting in increased precipitation chances, primarily south of the I-80 corridor. Generally, expect isolated to scattered showers and thunderstorms to begin to develop by late morning most days, with activity becoming maximized through the afternoon and early evening hours. Convection will be capable of periodic moderate to heavy rainfall, gusty erratic outflow winds, and lightning. Aside from the precipitation, this pattern will support moister daytime minimum relative humidity values, as well as improved overnight recoveries. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && Cheng/Mahan For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity
The Cedar City radar (KICX), 160 km away, was scanning. The volume nearest the first event began at 21:20 UTC.
1 flash flood. Local standard time, as filed.
Park rangers reported flooding on Sulphur Creek and adjacent drainages. Floooding in Capitol Gorge resulted in a multiday road closure of the Scenic Drive.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2023Every state in 2023This day in weather historyWarnings in Utah, August 2023
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1189173.