Thunderstorms formed across Utah during the first few days of August, producing strong gusty winds over the northwest deserts of Utah and flash flooding over portions of southern Utah.
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.
Thunderstorms formed across Utah during the first few days of August, producing strong gusty winds over the northwest deserts of Utah and flash flooding over portions of 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 2, 8:29 AM MST, 3 hours 46 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 929 AM MDT Thu Aug 2 2018 .SYNOPSIS...A moist and unstable airmass will remain over Utah and southwest Wyoming today. As high pressure weakens, the airmass will dry from the northwest Friday through the upcoming weekend. && .DISCUSSION...High pressure is centered over Arizona this morning, putting Utah and southwest Wyoming over a generally westerly flow aloft. Monsoonal moisture is in place, with PWs running in the 0.8 to 1.0 inch range over northern Utah and 1.0 to 1.2 inch over southern Utah, in excess of the 90th percentile for this time of year. In this moist airmass, some light showers have developed this morning, with the most activity over northern Utah and in the vicinity of a week shortwave over west central Utah. Cloud cover from the current shower activity may delay development of afternoon convection over northern Utah today, but with the moist airmass and daytime heating there should be enough fuel for showers and thunderstorms by late afternoon, with additional instability in the form of a shortwave coming by early evening. Southern Utah should see earlier development of convection with less in the way of cloud cover to inhibit convective development. Given the amount of moisture, heavy rain is possible with any storms that develop, and the light flow aloft makes things a bit more favorable for flash flooding. A prevailing westerly flow would put the greatest threat of flash flooding over the valleys of southeast Utah, which would include Capitol Reef NP. A trough moving over the top of the ridge is expected to flatten it a bit on Friday, acting to increase the westerly flow over the area, drawing drier air into the forecast area. The drying will initially be seen over northwest Utah but will spread over all but southeast Utah over the weekend. Temperatures will remain generally steady over the next few days with maxes running near to just above seasonal normals. No updates expected to the forecast this morning. && .AVIATION...VFR conditions at the KSLC terminal are expected today. Southerly winds should persist through most of today, becoming more gusty during the afternoon due to showers and thunderstorms developing in the area. Winds may become gusty and erratic due to convection between 19z and 05z. && .FIRE WEATHER...High pressure centered over Arizona is allowing for a westerly flow aloft across the forecast area this morning. Moisture rotating around this ridge along with a couple of weak weather disturbances is helping to maintain isolated showers and thunderstorms this morning, and these are expected to increase as the day goes on. The best coverage of convection will be over central and southern Utah this afternoon, with showers and thunderstorms increasing over northern Utah late this afternoon through the early evening. The high to the south will weaken Friday into the weekend, and this will bring drier air in from the northwest, resulting in decreasing coverage in showers and thunderstorms with a modest increase in westerly transport winds. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && PUBLIC/FIRE WEATHER...Traphagan AVIATION...Billingsley 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 515 AM MDT Thu Aug 2 2018 UTZ001>016-019>021-517-518-WYZ021-031200- Cache Valley/Utah Portion-Northern Wasatch Front- Salt Lake and Tooele Valleys-Southern Wasatch Front- Great Salt Lake Desert and Mountains-Wasatch Mountain Valleys- Wasatch Mountains I-80 North-Wasatch Mountains South of I-80- Western Uinta Mountains-Wasatch Plateau/Book Cliffs- Western Uinta Basin-Castle Country-San Rafael Swell- Sanpete/Sevier Valleys-West Central Utah-Southwest Utah- Utahs Dixie and Zion National Park-South Central Utah- Glen Canyon Recreation Area/Lake Powell-Central Mountains- Southern Mountains-Southwest Wyoming- 515 AM MDT Thu Aug 2 2018 This Hazardous Weather Outlook is for the western two thirds of Utah and southwest Wyoming. .DAY ONE...Today and Tonight Scattered showers and thunderstorms will be possible across the region today, with locally heavy rainfall, gusty winds, and small hail possible. Isolated incidents of flash flooding are possible across southern Utah through this evening. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Thunderstorms will remain possible across mainly central and southern Utah Friday afternoon and evening. Heavy rain and strong winds will be possible with the strongest storms. A drier westerly flow will follow for the upcoming weekend into early next week. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to standard operating procedures. 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), 52 km away, was scanning. The volume nearest the first event began at 19:17 UTC.
9 thunderstorm wind, 4 flash flood. Local standard time, as filed.
Heavy rain produced a flash flood at the Red Canyon Visitor Center that caused mud to cover half the parking lot.
The V-Grid sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 63 mph.
The APG sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 77 mph.
The Target R sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 63 mph.
The Romeo and Centerline sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 66 mph.
The Playa Station sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 61 mph.
The Salt Flats sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 67 mph.
The Upper Cedar Mountain Sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 60 mph.
The Dugway-W sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 60 mph.
The Camel Back Mountain sensor in the U.S. Army Dugway Proving Ground mesonet recorded a peak wind gust of 58 mph.
Heavy rain caused a flash flood in the upper drainage of the Paria River. The river was estimated to rise to 1000 CFS near the Old Paria Townsite.
Heavy rain caused a debris flow on the Willow Patch Fire burn scar. Due to this debris flow, state Route 24 was temporarily impassible between mileposts 17 and 18.
Heavy rain produced flash flooding at Capitol Reef National Park that temporarily closed Grand Wash Road and Capitol Gorge Road.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2018Every state in 2018This day in weather historyWarnings in Utah, August 2018
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: 779633, 779638, 779639, 779640, 779641, 779642, 779643, 779644, 779645, 779646, 779634, 779635, 779637.