Strong thunderstorms resulted in flash flooding in Capitol Reef National Park.
Every event with a place to put it. 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.
Strong thunderstorms resulted in flash flooding in Capitol Reef National Park.
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 Sep 28, 8:49 AM MST, 5 hours 41 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 949 AM MDT Tue Sep 28 2021 .UPDATE...Cold front continues its southeastward trek through northern Utah this morning, and as of 930AM MDT extends from Dugway northeast through the middle of the Salt Lake Valley and finally northeast through the center of Bear Lake. Expect a sudden wind shift to the NW with the passage of the front. Updated the forecast to increase forecast wind speeds and gusts through this afternoon, in line with latest high-resolution guidance as well as observational trends. Have also blended in the NBM 90th percentile winds. A few wind isolated wind gusts to Wind Advisory criteria (45 mph) are expected across wind prone locations of northwest and north-central Utah through this afternoon. Another location that may experience wind gusts near 45 mph this afternoon includes locations on the leeward side of the Traverse Mountains, as high resolution models indicate the development of a lee wave here. As a result, locations from Alpine to Saratoga Springs and the north end of Utah Lake may experience gusts near 45 mph from mainly 3PM-6PM. Considered the need for a Wind Advisory for zones 101, 103 and 106 but will hold off for now due to the relatively isolated nature of expected gusts to 45, but will continue to evaluate. Regardless, wind impacts will include rough, choppy water on area water bodies, as well as crosswinds and patchy blowing dust. An updated aviation discussion follows along with the previous discussion. Increasing low to mid-level frontogenisis will act upon modest elevated instability to aid in the development of isolated to widely scattered showers with an embedded thunderstorm or two across portions of central Utah this afternoon, inlcuidng the Utah valley and possibly the south end of the Salt Lake Valley. && .SYNOPSIS...A cold front will cross the state today through tonight bringing unsettled conditions and much colder temperatures. A gradual warming trend is expected Thursday into next weekend. && .SHORT TERM (Through 12Z/6AM Friday)... Early this morning, satellite imagery shows the slow cut-off low meandering through the desert southwest continuing to spin eastward near the New Mexico / Colorado boarder, with associated cloud cover and some showers spread westward across southeastern Utah. Meanwhile, upstream a northern stream trough can be seen moving in along the Pacific Northwest coast, with a strong poleward orient jet evident on the leading edge. Thus, the strong vorticity max over northern California this morning is expected to track northeastward into the Northern Rockies today. The surface front currently across southwest Idaho into central Nevada will therefore decouple from the upper-level support as it moves southeastward across northern Utah this morning and continues southward across the state today through tonight. Thus, while winds will shift to the northwest behind the front with a steady breezy, not expecting overly gusty conditions with this frontal passage. Also forcing for ascent will be shallow and weak with only the surface front supporting low-level convergence. It appears that enough moisture remains in place from the cut-off low to generate showers along the front from around Salt Lake County south and eastward today as the front moves through. Later this evening, a secondary, weaker vorticity max will move into western Utah. This will both interact with the surface front, which will be in place across southern into eastern Utah, and also generate a corridor of mid-level (700-500 mb) frontogenesis along a line from near Great Basin NP through Utah County to the Uinta Mountains. In addition, BUFKIT profiles show the potential for some weak elevated instability above 600 mb, and saturated ePV shows the potential for some conditional instability along this axis of mid-level frontogenesis. Thus while models continue to struggle on the exact placement, it appears likely that a band of moderate precipitation will develop roughly along this axis, with the potential for some rumbles of thunder and locally heavier / training precipitation. This area of frontogenesis will drift southeastward overnight and dissipate as the vort max moves through. Showers will continue over portions of central, southern an eastern Utah with the wave passage late tonight through Wednesday morning, with the best forcing for precipitation shift east into Colorado by Wednesday afternoon. However with the trough in place and linger low-level front in place across southern Utah, there could be a rejuvenation of showers and thunderstorms in the afternoon over the southern mountains. As for temperatures, expect much cooler weather through mid week. For locations that remains mixed this morning (like the SLC airport) temperatures are about as warm as they will be all day, with temperatures falling with the frontal passage by mid to late morning and struggling to recover a few degrees this afternoon. High temperatures will then run about 15 degrees below average on Wednesday. High pressure will build in Wednesday night through Thursday night. With a cooler, dry airmass in place coupled with light winds, these prime radiational cooling nights will likely result in areas of frost. Hard freeze conditions are likely for locations in the Bear River Valley, Wasatch Back, and upper Sevier River Valley, but these locations have already experienced a hard freeze this fall and thus will not qualify for additional headlines. Otherwise, there is a chance for isolated hard freeze conditions in portions of the Cache Valley and in outlying portions of Iron County, but confidence in a widespread hard freeze there is not high enough for any headlines at this time. NBM probabilities of a MinT of 28 or lower are only around 20 to 30 percent for these locations, so confidence will not support a watch and will mention the HWO for now. .LONG TERM (After 12Z/6AM Friday)... The latest operational models are faster in ejecting the closed low northeast into southern Colorado by 00Z Saturday then the cluster output generated 24 hrs earlier but this is still close enough to have a slight chance of wrap around precipitation across eastern portions of the forecast area Friday afternoon. Doubt any area receives more than a few hundredths. Once this trough exits the region Friday night the overall pattern is for ridging to prevail over the Great Basin. However, this ridging will be a narrow wedge between a trough backing westward over eastern Wyoming and a closed low somewhere off/or along the southern California coast. The ensemble means lend high confidence that a mild and dry forecast should prevail from Saturday through Monday, but looking at the operation models' runs, there is enough variation in location of these features that any shift in their locations will bring either cooler temperatures or higher probability of showers, especially Monday. By Tuesday. the NBM introduces showers into the southern 3/4 of the forecast area. This seems high considering the ensemble means still show ridging in place. Therefore, confidence is low to moderate towards the end of this extended forecast period. Temperatures will be slightly below normal Friday but based on the ridge dominating the extended period after Friday, temperatures are expected to be at or slightly above normal which means 70s in most valleys and near 90 degrees in Saint George. && .AVIATION.... KSLC...Gusty northwest winds are expected through mid to late afternoon behind the passage of a cold front around 9 am this morning. Occasional haze may cause MVFR or IFR visibilities. Decreasing winds can then be expected this evening. Skies are expected to stay VFR from mid-layer scattered to broken cloud decks. REST OF UTAH AND SOUTHWEST WYOMING... Across northern Utah and Evanston, gusty northwest winds are expected through late afternoon behind the passage of a cold front this morning. Gusts exceeding 30 mph are possible in some locations as well. Rain showers and the potential for a VCTS exists later this evening at KPVU, KHCR and KEVW. Decreasing winds can then be expected either later this afternoon or into the evening. Skies are expected to stay VFR from mid-layer scattered to broken cloud decks. For southern Utah sites, scattered thunderstorms are possible in the vicinity beginning late this evening. The frontal passage should reach southern Utah sites around midnight tonight; shifting wind directions. && .FIRE WEATHER... A cold front will cross the state from the northwest to southeast today through tonight, ushering in much cooler temperatures through mid week. Scattered showers some thunderstorms will develop along the frontal passage from around Salt Lake County south and eastward as the front tracks through central Utah this afternoon. By this evening, a secondary disturbance will move into western Utah and reinvigorate showers with some rumbles of thunder along a line from Great Basin NP to Provo to the western Uintas, with some north/south uncertainty in exact placement. Where this band of precipitation develops will have a better chance of wetting precipitation and intensities that may drive locally higher high elevation snow accumulations. Meanwhile more disorganized showers will continue south of this axis across southern and eastern Utah through Wednesday morning. Drier air will gradually filter southward by late Wednesday, ending precipitation chances from north to south. Temperatures will cool to around 15 degrees below average by Wednesday, with slow recovery to near normal temperatures going into the weekend. An isolated shower or thunderstorm will remain possible across portions of southern and eastern Utah during the Thursday-Saturday timeframe as modest lingering moisture combines with a couple of weak, passing disturbances. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && ADeSmet/NDeSmet/Church/Struthwolf 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 600 AM MDT Tue Sep 28 2021 UTZ101>131-WYZ021-291200- 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- 600 AM MDT Tue Sep 28 2021 This Hazardous Weather Outlook is for the western two thirds of Utah and southwest Wyoming. .DAY ONE...Today and Tonight A cold front will cross the state today and tonight. Some light snow accumulation is possible Tuesday night into Wednesday morning above 9000 feet across the northern and central mountains. Those with outdoor plans, particularly in the High Uintas, should be prepared for winter conditions Tuesday night into Wednesday. .DAYS TWO THROUGH SEVEN...Wednesday through Monday In the wake of the cold front, cold morning temperatures are expected Wednesday night into Thursday morning. Widespread frost is expected across many valleys including the Cache, Rush, Sanpete, and portions of west central and southern Utah. Only outlying areas of the Wasatch Front near Utah Lake and Tremonton are expected to see frost at this time. Hard freeze conditions will be possible in the Cache Valley, Wasatch Back, Bear River Valley, Sanpete Valley and near Panguitch. Those impacted by either widespread frost or hard freeze conditions in these areas should continue to monitor future forecasts. .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
The Cedar City radar (KICX), 160 km away, was scanning. The volume nearest the first event began at 21:29 UTC.
1 flash flood. Local standard time, as filed.
Flash flooding occurred in Capitol Gorge. The Scenic Drive was closed for over 24 hours due to flooding. Several vehicles were stuck, and required towing to be removed. Water and mud also flowed over state Route 24 east of the Hickman Bridge trailhead.
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, September 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: 986728.