Flash flooding occurred across portions of the Grand Staircase-Escalante National Monument, in Zion National Park, and in the town of Hilldale.
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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 occurred across portions of the Grand Staircase-Escalante National Monument, in Zion National Park, and in the town of Hilldale.
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 Jun 29, 3:13 AM MST, 11 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 413 AM MDT Tue Jun 29 2021 .SYNOPSIS...A weak area of low pressure will pull moisture northward across southern Utah today. This moisture will spread across the remainder of the area Wednesday, and remain in place through the end of the week. && .SHORT TERM (Through 12Z Friday)... The main concern today is the potential for flash flooding in southern Utah. Forecast confidence remains high enough for an elevated Flash Flood Potential Rating of Probable for many southern Utah basins, however not high enough for a Flash Flood Watch at this time. Regardless, recreationists and visitors to southern Utah will want to remain weather aware today and alert to the elevated flash flood risk today. Strong high pressure remains in place over the Pacific Northwest early this morning while a weak low pressure system is wrapping into central Utah from the east this morning in the anticyclonic flow around the high. This low is helping to pull in higher moisture content air from Arizona and New Mexico into southern Utah, while also supplying synoptic forcing for ascent across southern Utah. Overnight, convection has been ongoing across far southeastern Utah, while spotty light showers are developing across southwestern and south-central Utah already and drifting southward. This appears to be precursor to the expect convection this afternoon in southern Utah, which should become fairly widespread given the instability and weak forcing for ascent. The main concerning environmental variables for an elevated flash flood risk today are the increasing PW values over 0.75 inches, light northerly steering flow, and sufficient instability 500-1000 J/kg to drive efficient rain production in thunderstorms. With this, expect to see convective initiation this afternoon over the higher terrain of the southern Utah mountains, with locally heavy rainfall appearing likely over the higher, less flash flood prone terrain. However, expect this initial convection will develop a strong cold pool given the relatively dry low levels, and LCLs over 5000 feet per the BCE BUFKIT profile. Given this, there is potential for the cold pool to rush southward, and despite some southeasterly background flow into the Grand Staircase, a quickly propagating cold pool may not allow newly developing stroms much residence time over flash flood prone areas as storms move down basin. However, given this expected storm motion down drainages into the Grand Staircase, Zion and St George areas, will maintain the 'probable' flash flood threat category for these areas in the Flash Flood Potential Rating, with lower 'possible' ratings for locations to the east like Capitol Reef and the Swell. Moving into Wednesday and Thursday, moisture will remain in place along with the remnant lower heights aloft of the decayed mid- level wave over Utah. With less descript forcing, and continued weak flow, expect convective evolution on Wednesday to be more tied to orographic initiation, and farther northward across central and into northern Utah, with the potential for southern Utah to struggle a bit more with instability with remnant cloud cover and outflow boundaries form the previous day's convection. Given this lower confidence, and latest HREF members seeming to back up this thinking of less coverage over southern Utah on Wednesday, have maintained only 'possible' wording in the Flash Flood Potential Rating for southern Utah. However, burn scars across central and northern Utah may be more at risk on Wednesday, and potentially Thursday as well with another round of daytime thunderstorms. .LONG TERM (After 12Z Friday)... The long term forecast remains on par with the previous forecast packages. An influx of moisture into southern will continue with this moisture eventually expanding into northern Utah over the weekend. With this moisture combined with daytime heating, diurnal convection is expected to develop each afternoon throughout the long term forecast period. Initiation points will be along the higher terrain. As the first round of storms dissipate outflow boundaries will become an additional catalyst for thunderstorm development which will increase the thunderstorm coverage. Aloft, very weak steering flow through the low to mid levels will translate to very slow storm motion, thus storms will pose a flash flooding risk as storms will be efficient rain producers. Additionally, we can't rule out the possibility of a few storms becoming strong and/or severe. The introduction of increasing moisture and afternoon skies becoming cluttered with cumulus fields and thunderstorm anvil debris, should keep temperatures steady through the weekend and into the early parts of next week. A more noticeably warmup, with drier conditions could enter the forecast toward the end of the long term forecast, as indicated by some long range model outputs with a return of a southwesterly flow returning across the Great Basin. Still too early to pinpoint the finer details and large discrepancies amongst the models are yielding to a low confidence forecast in the day 6-7 timeframe at this time. && .AVIATION... KSLC...VFR conditions are expected across the KSLC terminal throughout the valid TAF period. Very light easterly winds will transition back to the typical southerly drainage flow by 12z. A shift to a northerly flow by 19z is expected and will turn breezy around 21z. Expect wind gusts in the 18-22 knot range throughout the afternoon hours. Rest of Utah and southwest Wyoming...The northern half of the airspace will maintain VFR conditions throughout the valid TAF period. Afternoon cumulus are expected to form primarily along the higher terrain by 18z. Afternoon convection across the central and southern Utah airspace will bring the hazards of strong and erratic winds in and around thunderstorm cores. Additionally, thunderstorms that directly impact a terminal may bring brief periods MVFR visibility. The window for thunderstorm activity across these airspace's will be between 18-03z. && .FIRE WEATHER... Strong high pressure will remain in place across the Pacific Northwest and western Northern Rockies, while a weak low pressure system slides into Utah today. This weak low will help draw moisture northward into southern and portions of central Utah today. Expect showers and thunderstorms to develop this afternoon over the higher terrain and generally track southward into lower elevations of southern Utah. Thunderstorms are expected to be efficient rain producers combined with slow storm motions should keep storms wetting. Moisture will spread farther north on Wednesday, and will remain in place through the end of the week maintaining daily shower and thunderstorm chances. Thus despite a slow warming temperature trend through the week, humidity will remain higher than we've seen with better overnight recoveries. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && SHORT TERM...Church LONG TERM...Woodward AVIATION...Woodward FIRE WEATHER...Church For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity For frequently asked questions about the Area Forecast Discussion visit... http://weather.gov/saltlakecity/general/afd_faqs.php
Hazardous Weather Outlook National Weather Service Salt Lake City UT 417 AM MDT Tue Jun 29 2021 UTZ101>131-WYZ021-301200- Great Salt Lake Desert and Mountains-Tooele and Rush Valleys- Eastern Box Elder County-Northern Wasatch Front-Salt Lake Valley- Utah Valley-Cache Valley/Utah Portion-Wasatch Back- Bear Lake and Bear River Valley-Wasatch Mountains I-80 North- Wasatch Mountains South of I-80-Western Uinta Mountains- Wasatch Plateau/Book Cliffs-Western Uinta Basin- Western Millard and Juab Counties-Eastern Juab/Millard Counties- Central Mountains-Sanpete Valley-Sevier Valley-Castle Country- San Rafael Swell-Southwest Utah-Lower Washington County- Zion National Park-Southern Mountains-Upper Sevier River Valleys- Bryce Canyon Country-South Central Utah- Capitol Reef National Park and Vicinity-Western Canyonlands- Glen Canyon Recreation Area/Lake Powell-Southwest Wyoming- 417 AM MDT Tue Jun 29 2021 This Hazardous Weather Outlook is for portions of central Utah... northern Utah...southern Utah...southwest Utah and southwest Wyoming. .DAY ONE...Today and Tonight Flash flooding is possible today in southern Utah, especially in slot canyons and normally dry washes, as thunderstorms capable of heavy rainfall are expected to develop this afternoon through early evening. .DAYS TWO THROUGH SEVEN...Wednesday through Monday From Wednesday through remainder of the week, scattered afternoon and evening thunderstorms are expected, bringing an increased risk of flash flooding to slot canyons, small streams, and normally dry washes as well as the potential for debris flows near recent burn scars. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed. Please relay any information about observed severe weather to the NWS while following all local, state, and CDC guidelines. For more information from NOAA/s National Weather Service visit... http://weather.gov/saltlakecity For information on potential road travel impacts visit... http://www.udottraffic.utah.gov/roadweatherforecast.aspx
Special Weather Statement
National Weather Service Salt Lake City UT
309 PM MDT Tue Jun 29 2021
UTZ122-125-292145-
Southwest Utah UT-Southern Mountains UT-
309 PM MDT Tue Jun 29 2021
...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL IRON COUNTY UNTIL
345 PM MDT...
At 308 PM MDT, National Weather Service Doppler radar indicated a
strong thunderstorm 15 miles north of Beaver Dam State Park, or 15
miles north of Beaver Dam...moving southwest at 15 mph.
Penny to nickel size hail and wind gusts up to 50 mph will be
possible.
This storm will remain over mainly rural areas of west central Iron
County.
This includes Utah Route 56 between mile markers 1 and 7.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If threatening weather approaches, take shelter in a sturdy building.
&&
LAT...LON 3781 11396 3772 11386 3761 11390 3761 11405
3778 11405
TIME...MOT...LOC 2108Z 040DEG 13KT 3773 11402
MPSThe Cedar City radar (KICX), 130 km away, was scanning. The volume nearest the first event began at 21:30 UTC.
4 flash flood. Local standard time, as filed.
Flash flooding was observed at the state Route 12 overpass of the Escalante River. Additional reports of flash flooding were observed upstream, including in Escalante River Canyon and at Death Hollow. The Escalante River gauge climbed from no flow to 400 CFS.
Hildale Fire Department personnel reported multiple road closures in town, multiple flooded residences, and several stranded motorists due to flash flooding in the area.
Significant flash flooding occurred from the entrance of Zion National Park, across the eastern portions of the park. State Route 9 within the park closed due to flooding and debris on the roadway.
Widespread flash flooding occurred from Wire Pass to the mouth of Buckskin Gulch. Several hikers were stranded between Wire Pass and the entrance to Buckskin Gulch, with muddy water levels rising to waist deep. Another group was trapped within Buckskin Gulch overnight due to Flash Flooding. The group was able to climb onto narrow ledges above the flood waters, where they remained overnight, then evacuated the next day.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2021Every state in 2021This day in weather historyWarnings in Utah, June 2021
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: 968140, 968145, 968152, 968155.