A deep monsoonal event impacted Utah at the beginning of August. Each of these days across northern Utah, widespread thunderstorms and flooding impacted the region.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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.
A deep monsoonal event impacted Utah at the beginning of August. Each of these days across northern Utah, widespread thunderstorms and flooding impacted the region. Very heavy rainfall impacted West Valley City, Honeyville, and Draper in particular.
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 1, 1:34 PM MST, 1 hour 20 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 234 PM MDT Tue Aug 1 2023 .SYNOPSIS...Monsoon moisture will remain in place across the region through midweek. A gradual drying trend will begin Thursday across southern Utah, reaching northern Utah Friday. A drier, more stable pattern is expected for much of the state this weekend into early next week. && .SHORT TERM (Through 12Z Thursday)...A surge of monsoon moisture has elevated precipitable water values above 1 inch across the forecast area based on both GOES derived imagery and the 12Z KSLC sounding. Observed surface dew points are in the 50s to low 60s across the forecast area. This moisture-rich airmass has elevated the flash flood threat across the area. However, persistent morning cloud cover delayed surface heating over much of the forecast area, and continues to do so across southwest Utah where afternoon temperatures have only reached the low 80s in St George within the last hour or so. Clearing skies across northern and central Utah has allowed convection to quickly develop across the higher terrain this afternoon, however up to this point this activity has remained relatively weak and disorganized. A remnant MCV is noted slowly lifting into central Utah, and as this feature continues to slowly lift north and interact with a destabilizing airmass ahead of it, anticipate convection to increase in coverage across central and eventually northern Utah heading into the evening hours, while activity across the south remains more isolated in nature. Remnant cloud cover/precipitation will likely linger overnight into the morning hours across northern Utah, mainly north of I-80. A weak shortwave currently approaching the Baja/southern CA coast is forecast to lift northeast overnight, crossing the forecast area during the day Wednesday. This has been fairly consistently advertised in the models, and as this feature interacts with the moisture-rich airmass in place, the potential exists for a more organized convective threat across the area Wednesday afternoon/evening. CAM guidance suggests an organized line is likely to develop across west central Utah in association with this wave, spreading northeast into the Wasatch Front with a threat for strong winds in addition to heavy rain late Wednesday afternoon/Wednesday evening, while additional convection to the south poses a heavy rain/flash flood threat across central and southern Utah. Given the moisture-rich airmass in place have maintained probable flash flood potential for Wednesday, but held off on a watch given uncertainly in coverage/evolution across southern Utah. .LONG TERM (After 12Z/6AM Thursday)...Many of us along the Wasatch Front will be waking up to rainfall Thursday morning as widespread precipitation is expected to be centered from the Salt Lake Valley to the Idaho border. This will result from an area of low pressure / shortwave tracking through eastern Idaho, northern Utah and into Wyoming. Precipitation is likely to persist much of the day, leading to rainfall amounts most likely in the range from 1/4 to 1/2 inch for totals. Right now, there is about a 20% chance for more than 1/2 inch of rain (on Thursday). All of this is bolstered by shift of tail guidance indicating abnormally wet conditions across northern Utah and southwest Wyoming. By Thursday evening, precipitation is expected to decrease across northern Utah. Across central and southern Utah, chances for rain and thunderstorms will be more scarce and more tied to terrain in the afternoon. Headed toward Friday and into the weekend, our forecast becomes a bit more chaotic and somewhat less certain. On Friday, all the cluster means indicate at least degree of high pressure building in from the south while the low pressure system / shortwave tracks further into Wyoming and into the Dakotas. However, by the weekend, about 20% of ensembles members are favoring another shortwave over Idaho, which would bring another round of rain and thunderstorms across the northern half of Utah. Otherwise, the remaining 80% of members indicate some variation of a weak ridge of high pressure over Utah with low pressure disturbances east of the Rocky Mountains. The ridge then looks to shift gradually westward over the southwestern US while low pressure disturbances remain mostly to our east. Flow then shifts more out of the northwest over Utah by the beginning of next week. Some of the disturbances may develop far enough west to enable limited chances for showers and thunderstorms for eastern Utah and southwest Wyoming. The other weather story to mention this week is our temperature change. Beginning Thursday and continuing through Tuesday of next week, much cooler, below average temperatures are forecast particularly across northern Utah. Temperatures 5 to 10 degrees below averages for August are forecast with the coolest day currently expected on Thursday. While a few degrees cooler are forecast in central and southern Utah late in the week, noticeably cooler temperatures are less likely here. && .AVIATION...KSLC...Monsoonal pattern persists, with scattered convection expected through the evening. By late evening on through the night, anticipate activity to largely become more stratiform in nature, with a period of fairly continuous to off and on light rain. Wednesday, expect increasing scattered convective development by late morning into the afternoon. Some models suggest a stronger period of convection possible ~22z-02z which will be something to monitor. Largely expect VFR conditions outside any stronger cells. .REST OF UTAH AND SOUTHWEST WYOMING...Monsoonal pattern will persist through the TAF period. Scattered showers and thunderstorms will continue into the evening, with guidance suggesting a lull at southern terminals overnight. At northern terminals, areas of more stratiform light rain will likely persist through much of the night. Activity will begin to move back in to southern terminals by mid morning Wednesday, with increasing convection elsewhere by late morning to early afternoon. Per usual, convection will be capable of lightning, periodic moderate to heavy rain, and gusty erratic outflow winds. Periodic reduction to CIGS/VIS possible in stronger storms, but otherwise expect VFR conditions to persist. && .FIRE WEATHER...A surge of monsoon moisture will remain across the region through Wednesday, resulting in several rounds of showers and thunderstorms accompanied by wetting rains. This moisture surge will continue to result in cooler temperatures, and elevated daytime humidity with good to to excellent overnight recovery. Drier air will begin to spread across southern Utah Thursday while moisture remains in place across the north. A general drying trend will follow for the upcoming weekend into early next week. Very dry air, characterized by afternoon RH values below 15%, will reside across southern Utah Friday through the upcoming weekend. Further north, afternoon RH values across northern and west central Utah valleys will generally run in the 25-35% range Friday through Sunday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && Seaman/NDesmet/Warthen For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity
Special Weather Statement
National Weather Service Salt Lake City UT
311 PM MDT Tue Aug 1 2023
UTZ108-110>112-012200-
Wasatch Back UT-Western Uinta Mountains UT-Wasatch Mountains I-
80 North UT-Wasatch Mountains South of I-80 UT-
311 PM MDT Tue Aug 1 2023
...A strong thunderstorm will impact portions of eastern Salt Lake...
northwestern Wasatch...south central Morgan and southwestern Summit
Counties through 400 PM MDT...
At 310 PM MDT, Doppler radar was tracking a strong thunderstorm over
South Snyderville Basin, or near Park City, moving northwest at 10
mph.
HAZARD...Wind gusts up to 50 mph.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects.
Locations impacted include...
Park City, Summit Park, Oakley, North Snyderville Basin, Wanship,
South Snyderville Basin, Mill Creek Canyon, Peoa, Kimball Junction,
Jordanelle Reservoir, Rockport State Park and Snyderville.
This includes the following highways...
Interstate 80 in Utah between mile markers 141 and 157.
US Route 40 between mile markers 0 and 8.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4077 11124 4061 11140 4068 11164 4090 11152
TIME...MOT...LOC 2110Z 119DEG 9KT 4072 11148
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH
HMSpecial Weather Statement
National Weather Service Salt Lake City UT
340 PM MDT Tue Aug 1 2023
UTZ108-110-112-012230-
Wasatch Back UT-Western Uinta Mountains UT-Wasatch Mountains I-
80 North UT-
340 PM MDT Tue Aug 1 2023
...A strong thunderstorm will impact portions of southeastern Morgan
and northwestern Summit Counties through 430 PM MDT...
At 339 PM MDT, Doppler radar was tracking a strong thunderstorm near
Coalville, moving southwest at 20 mph.
HAZARD...Wind gusts up to 50 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Coalville, East Canyon State Park, Wanship, Henefer, Emory,
Hoytsville, Croydon, Echo, Rockport State Park and Echo Reservoir.
This includes the following highways...
Interstate 84 between mile markers 108 and 119.
Interstate 80 in Utah between mile markers 153 and 181.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4118 11149 4106 11114 4075 11136 4092 11172
TIME...MOT...LOC 2139Z 035DEG 17KT 4097 11136
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
HMSpecial Weather Statement
National Weather Service Salt Lake City UT
353 PM MDT Tue Aug 1 2023
UTZ108-111>113-012245-
Wasatch Back UT-Wasatch Plateau/Book Cliffs UT-
Western Uinta Mountains UT-Wasatch Mountains South of I-80 UT-
353 PM MDT Tue Aug 1 2023
...A strong thunderstorm will impact portions of northwestern Wasatch
and north central Utah Counties through 445 PM MDT...
At 352 PM MDT, Doppler radar was tracking a strong thunderstorm over
Wasatch Mountain State Park, or 7 miles southwest of Heber City,
moving west/southwest at 10 mph.
HAZARD...Wind gusts up to 50 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Heber City, Heber, Daniel, Wasatch Mountain State Park, Midway,
Charleston, Wallsburg, Deer Creek State Park and Sundance.
This includes US Route 40 between mile markers 11 and 24.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4061 11144 4043 11131 4032 11157 4052 11172
TIME...MOT...LOC 2152Z 059DEG 8KT 4045 11153
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH
HMThe Salt Lake City radar (KMTX), 101 km away, was scanning. The volume nearest the first event began at 21:55 UTC.
23 thunderstorm wind, 14 flash flood, 3 flood, 2 high wind, 1 hail. Local standard time, as filed.
At Alta Lodge, along state Route 210, flooding left mud and debris on the road, with cars stuck and some homes flooded.
Videos and reports of flooding and mudslides in Indian Canyon near mile post 278.
Rocky Mountain Power outage of 11,000+ customers resulting from crane hitting power lines. Crane was reported to have fallen in part due to high winds.
A Mesonet station southeast of Hinckley recorded a peak gust to 61 mph.
Zion National Park reported flash flooding near Twin Brothers Mountain, just north of SR-9.
Mesonet station UT26 at i-15 at the Sevier River gusted to 61 mph.
Mesonet station SBWU1 at Sevier Reservoir gusted to 62 mph.
Mesonet station PC349 at Nephi West gusted to 77 mph.
Mesonet station UTRKY at Rocky Ridge recorded a gust of 66 mph.
Mesonet station FG024 at West Mountain South recorded a wind gust of 58 mph.
Mesonet station UTBRC I-15 at Beer Creek recorded a wind gust of 60 mph.
Mesonet station VRH at Vernon Hill recorded a wind gust of 62 mph.
AWOS station KPVU at Provo Municipal Airport recorded a wind gust of 64 mph.
Mesonet station SND at Arrowhead Summit recorded a wind gust of 61 mph.
A carport partially collapsed at an apartment complex.
Mesonet station PC034 at Provo Canyon recorded a wind gust of 63 mph.
Mesonet station UTCHL at US-189 at Charleston recorded a wind gust of 61 mph.
Mesonet station AS768 at Great Salt Lake Marina recorded a wind gust of 61 mph.
Mesonet station UTRVT at SR-154 at mile post 7 at Riverton recorded a wind gust of 64 mph.
A tree fell on a car.
Public reported one inch hail.
Mesonet station PC022 at Mount Aire Canyon recorded a wind gust of 59 mph.
Two 2-inch tree branches downed from an otherwise healthy tree.
There were reports of street flooding, road closures, and vehicles stranded.
Mesonet station UT201 at SR-201 at I-80 recorded a wind gust of 70 mph.
Mesonet station KCC01 6.0 NE of Lake Point recorded a wind gust of 58 mph.
Multiple streets and Hunter High School in West Valley City were flooded. Flooding led to vehicles stranded along California Avenue between 2700 West and Gladiola Street in Salt Lake City.
Significant flow off of the Jacob City burn scar into Soldier Canyon and Soldier Creek. The road going up Soldier Canyon was closed. SR-36 was closed south of Stockton due to debris and flood waters starting to top the culvert on to SR-36.
Flooding was observed at the underpass in Kaysville at the 200 North exit.
Flash Flooding was observed at the underpass in Kaysville at the 200 North exit.
Multiple streets and Hunter High School in West Valley City were flooded.
Flooding was reported in Corrine where 3.44 inches of rain was recorded. There was 5.83 inches of rain measured in Honeyville. Reports of basement flooding and photos of flooding to crops, farmland, and yards were observed.
Flooding was reported in Corrine. Reports of basement flooding and photos of flooding to crops, farmland, and yards were observed. A rainfall amount of 3.44 inches was recorded in Corrine.
Homes were flooded in Honeyville, where 5.66 inches of rain fell from August 1 to August 3.
Diamond Fork Road was closed between the Diamond Campground and Three Forks Trailhead due to water and mud on the road.
A wind gust of 66 mph was recorded at the Bonneville Salt Flats mesonet site.
Mesonet site BFLAT at the Bonneville Salt Flats recorded a wind gust of 66 mph.
Mesonet station DW9435 at Draper recorded a wind gust of 68 mph.
Street flooding was reported in Sandy around 1000 East.
Flash flooding led to vehicles stranded along California Avenue between 2700 West and Gladiola Street in Salt Lake City.
Late on August 3, the city of Draper declared a state of emergency as flash flooding and mudslides led to road closures on Highland Drive, Bangerter Parkway, and Minuteman Drive. A portion of Bangerter Parkway, near 14200 South, was damaged on the uphill lanes. A number of homes sustained water damage. According to the City of Draper, there were 428 residential damage report forms submitted, with estimated damages of $11,255,765. There were 11 business damage report forms submitted, with estimated damages of $844,235. City infrastructure estimated damage totaled $4,000,000.
A wind gust of 68 mph was recorded in Draper.
Large debris flow through Soldier Canyon off the Jacob City burn scar. Water and debris is flowing across SR-36.
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: 1133263, 1189035, 1189262, 1189263, 1189032, 1189264, 1189265, 1189266, 1189267, 1189268, 1189269, 1189270, 1189271, 1189272, 1189275, 1189276, 1189277, 1189278, 1189279, 1189280, 1189281, 1189282, 1189283, 1189038, 1189285, 1189284, 1189025, 1189030, 1189024, 1133249, 1133211, 1188985, 1132729, 1132731, 1133230, 1133511, 1189287, 1189286, 1132727, 1133256, and more.