Heavy rain brought flash flooding to several places in southern Utah.
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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.
Heavy rain brought flash flooding to several places in southern Utah.
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 24, 2:04 PM MST, 4 hours 56 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 304 PM MDT Thu Aug 24 2023 .SYNOPSIS...Monsoon moisture will remain across the region through Friday. High pressure will bring a warming and drying trend beginning Saturday, and continuing into early next week. && .SHORT TERM (Through 12Z Saturday)...Afternoon satellite imagery shows the well defined remnant circulation from Tropical Storm Harold spinning across southeastern Utah. Extensive cloud cover has thinned this afternoon, allowing for scattered convection across the forecast area. Despite dew points in the 50s to low 60s, and PW values near or above 1", instability remains somewhat meager owing to modest mid level lapse rates. However, this is favoring very efficient rain processes as observed at several mesonet locations across the Wasatch Plateau/western Uintas earlier this afternoon, where 0.50 or greater in 30 minutes was observed from otherwise innocuous looking convection. This threat will persist into the evening hours, mainly along and east of the I-15 corridor. Down-drainage storm motions across south central Utah will elevate the flash flood potential from Zion east through the Staircase and into the Glen Canyon Rec area. The remnants of Harold will weaken and lift northeast into northern Colorado/southern Wyoming by Friday, with ample low level moisture lingering across the forecast area. Again, modest mid level lapse rates will limit instability, and hi-res guidance seems to reflect this with scattered at best convection firing Friday afternoon. Given the ample moisture a threat of flash flooding will remain, but will be more localized given the limited convective coverage. .LONG TERM (After 12Z Saturday)...There is good agreement from models on a retrograding ridge that will allow for much drier conditions for the weekend into the week. The best moisture content locally Saturday will be for eastern Utah. Precipitable water values will be around 1" throughout eastern Utah, while drier conditions build into western portions of Utah as synoptic winds transition to southwest. The ridge will retrograde into the southwest Sunday. Shower and thunderstorm chances will decrease, with the best chances near higher terrain. Most of Utah will have dry conditions with temperatures warming above normal. Valley high temperatures will get into the 80s and 90s, with upper 90s or low 100s for lower Washington County. A trough will be largely stationary off the coast of the PacNW, and as the ridge retrogrades more into the start of the week, that trough will build inland. Monday conditions will be similar to the weekend. As the trough pushes into the PacNW, enhanced southwest flow will build into northern Utah. This will allow for warmer temperatures, with highs 5-10F warmer than normal. The trough will flatten the ridge out Wednesday, with stronger winds. Gusts will reach more than 30 knots for southwest Wyoming and most of Utah. Temperatures will drop around 5F from Tuesday. More active weather is forecast by Wednesday as ridging builds to the southeast with monsoonal moisture advection into the southwest. && .AVIATION...KSLC...VFR conditions will prevail through the remainder of the period for the KSLC terminal. Isolated and slow moving storms will be possible through this evening which could create brief gusty and erratic winds. A northerly lake breeze will be late to establish, if at all, before switching back to southerly this evening. .REST OF UTAH AND SOUTHWEST WYOMING...Mostly VFR conditions will persist throughout the period. Isolated slow moving storms will linger through the evening before diminishing. These storms will create gusty and erratic winds and could briefly reduce categories. Otherwise, winds will be light and variable with a few CIGs near ridgetop that could create brief mountain obscuration. && .FIRE WEATHER...An anomalously moist airmass will continue to bring elevated humidity along with scattered showers and thunderstorms capable of producing heavy rainfall across the region through Friday. A chance in the large scale weather pattern will begin Saturday, as high pressure strengthens across the region bringing a warming and drying trend over the weekend into early next week. By Tuesday this high will shift east of the area, allowing a very warm and dry southwesterly flow to spread across the region. This may result in locally breezy to windy conditions Tuesday and Wednesday, particularly across western valleys. This warmer and drier period looks to be short lived, as monsoon moisture returns to the region during the latter portion of next week. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && Seaman/Wilson/Mahan For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity
The Cedar City radar (KICX), 101 km away, was scanning. The volume nearest the first event began at 01:59 UTC.
6 flash flood. Local standard time, as filed.
A flash flood was observed on Wahweap Creek.
The Dirty Devil Gauge near Hanksville reported a rise over 700 cfs.
Flooding was reported in the town of Bicknell, with water flowing across streets.
The Paria River near Kanab gauge recorded a spike to just over 400 cfs.
Debris with mud was reported in Huntington Creek resulting from flow from the Trail Mountain Burn Scar.
A flash flood was reported in Capitol Gorge and Grand Wash.
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: 1189233, 1189260, 1189246, 1194988, 1189247, 1189248.