Scattered severe thunderstorms brought strong winds, wind damage, and hail to northern 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.
Scattered severe thunderstorms brought strong winds, wind damage, and hail to northern 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 May 15, 8:18 PM MST, 3 hours 52 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 918 PM MDT Sat May 15 2021 .SYNOPSIS...A slow moving upper level low will bring unsettled conditions to the region through early next week. && .DISCUSSION...A broad upper low is centered over central California this evening as it continues slowly southward. Over Utah and southwest Wyoming, some strong convection developed this afternoon on the front side of the low over eastern Nevada/northwest Utah, with additional strong to severe convection over southwest Wyoming in an area of enhanced instability due to a shortwave ejecting from the main low. Some wind gusts in excess of 30 mph continue over the west desert in association with these weakening showers. Additional spotty shower activity was observed over portions of eastern Utah, but was not as organized in nature due to weaker instability. With the loss of daytime heating, lingering shower activity is diminishing with little in the way of showers anticipated overnight. The position of the low over California puts a bit of an easterly pressure gradient over northern Utah and southwest Wyoming, becoming more noticeable as the low continues south. This brings the possibility of some slight enhancement of canyon winds along the Wasatch Front tonight and possibly tomorrow night. However, given that this gradient is relatively weak and does not have cold advection associated with it, impacts will be limited. Gusts up to 40 mph can be anticipated over prone areas through the overnight hours. By late tomorrow morning, the low will find itself centered near Las Vegas before it starts trekking eastward across the Desert Southwest. With increasing moisture in a continued unstable airmass, anticipating another round of convection, with the threat extending across much of northern and central parts of the forecast area given more favorable jet support. A weak boundary stalled over northern Utah will provide additional instability from about the Salt Lake valley northward. Lower levels remain on the dry side, so gusty winds will be the main threat with storms that develop. Far southern Utah will remain quite dry with winds staying breezy in areas, resulting in critical fire weather conditions where fuels are dry. See the fire weather section of the AFD for more details. The low's eastward journey across the Desert Southwest continues on Monday, with the center of the system expected to reach the Four Corners region by Monday evening. This will allow temperatures over Utah and southwest Wyoming to cool to near or just above seasonal normals. The influence of the trough will keep the airmass over the area unstable with some increase in moisture. The threat of showers and thunderstorms is expected to spread into southern Utah, with the higher terrain across the state seeing the brunt of convection. By Tuesday evening, the trough is finally expected to exit the area, with the convective threat during the day Tuesday primarily limited to the eastern half of the forecast area. Weak ridging is then expected to develop for the middle of the week, before a stronger and colder system potentially impacts the area late in the upcoming week. No updates expected to the forecast this evening. && .AVIATION...KSLC...The SLC terminal will see VFR conditions through the night with some scattered clouds. Northwest winds are expected to shift to the southeast between 07Z and 09Z. Rest of Utah and southwest Wyoming...With showers over portions of the area diminishing this evening with the loss of daytime heating, TAF sites across the area will see VFR conditions. Due to the pressure gradient, many northern Utah TAF sites including LGU, EVW, and OGD will see prevailing easterly winds overnight and into the morning with southerly winds remaining in place over the southern TAF sites including CDC, SGU, and BCE. Convection developing tomorrow afternoon across primarily northern and central portions of the forecast area will result in some areas of gusty and erratic winds. && .FIRE WEATHER...A slow moving upper low will keep unsettled weather over the district through early next week. Over northern and central Utah, high based showers and thunderstorms will once again develop Sunday afternoon into Sunday evening, bringing the possibility of gusty and erratic downburst winds. Over southern Utah, dry conditions and breezy winds will continue, resulting in areas of critical fire weather conditions where fuels are dry. As moisture increases Monday, the threat of showers and thunderstorms will spread across the majority of the district. Gusty winds will again be the main impact but there will be a slight chance of wetting rain. As the low exits Tuesday, some convection is possible across eastern portions of the district before drier conditions return for Wednesday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Red Flag Warning until 9 PM MDT Sunday for UTZ495-497-498. WY...None. && Traphagan 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 839 AM MDT Sat May 15 2021 UTZ101>131-WYZ021-161300- 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- 839 AM MDT Sat May 15 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 High based showers and thunderstorms are possible across much of northern Utah as well as the higher terrain of central and southern Utah and adjacent valleys. The main threat for most locations will be gusty, microburst winds. Areas near the Utah/Nevada border and across far northeastern Utah and Uinta County Wyoming may also see small hail. Critical fire weather conditions will continue across southern Utah today due to gusty winds and low humidity. .DAYS TWO THROUGH SEVEN...Sunday through Friday Critical fire weather conditions are expected again across southern Utah due to gusty winds and low humidity. Isolated to scattered showers and thunderstorms across northern Utah and central Utah on Sunday and spreading into southern Utah on Monday will be capable of producing gusty winds. .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 Salt Lake City radar (KMTX), 143 km away, was scanning. The volume nearest the first event began at 07:12 UTC.
8 thunderstorm wind, 6 hail. Local standard time, as filed.
A peak wind gust of 64 mph was recorded by the Interstate 80 at Milepost 2 Tripod sensor.
One-inch diameter hail fell in Herriman.
Nickel-sized hail fell near Tooele.
Nickel-sized hail fell in North Ogden.
Quarter-sized fell in Plain City.
Quarter-sized hail fell near Logan.
The Gunnison Island sensor recorded a peak wind gust of 76 mph.
Penny-sized hail fell in Park City.
The Flight Park South sensor recorded a peak wind gust of 61 mph.
Small trees were snapped in half in the Salt Lake Valley.
The Interstate 80 at Grassey sensor recorded a peak wind gust of 63 mph.
The Salt Flat sensor recorded a peak wind gust of 63 mph.
The Horizonal Grid sensor recorded a peak wind gust of 63 mph.
The Great Salt Lake Minerals sensor recorded a peak gust of 59 mph.
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, May 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: 962625, 962617, 962619, 962620, 962621, 962622, 962626, 962623, 962627, 962624, 962628, 962630, 962631, 962632.