An approaching trough helped provide enough synoptic support in combination with available moisture to trigger isolated to scattered convection across the northern half of Utah or so. A few of these thunderstorms produced strong to severe wind gusts.
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.
An approaching trough helped provide enough synoptic support in combination with available moisture to trigger isolated to scattered convection across the northern half of Utah or so. A few of these thunderstorms produced strong to severe wind gusts.
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 20, 2:43 PM MST, 2 hours 57 minutes earlier.
Area Forecast Discussion National Weather Service Salt Lake City UT 343 PM MDT Sat Sep 20 2025 .SYNOPSIS...An unsettled pattern persists into early next week along with a cooldown at many locations following the passage of a cold front. Drier conditions are then expected through midweek, with some moisture starting to return late in the work week && .SHORT TERM (Through 00z Tuesday)...A remnant trough continues to slowly lift through overhead this afternoon. This feature is helping to maintain a fairly moist environment, with PWAT values around 150% to 200% of climatological normal. This in combination with ongoing destabilization is resulting in isolated to scattered convective development across the area, especially at locations further north where the aforementioned trough is helping provide a little more lift. That said, lingering cloud cover from the morning has resulted in a more gradual increase in instability, though satellite trends show more breaks starting to develop. As such, think the HREF 25th- 75th percentile range of SBCAPE around 100-500 J/kg seems reasonable. With the extra moisture and higher dew points, LCLs are around 1000 to 2000 m, and DCAPE values are a bit meager. While a stronger storm or two may be able to produce some modestly gusty outflow winds still, thinking the threat of gusts in excess of 50 mph or so is pretty low. With the moister environment and somewhat slow storm motion, periods of moderately heavy rain (in addition to lightning) seem to be the biggest threat today. Coverage and intensity of activity will decrease with loss of heating through the evening hours, but sufficient upper level support will remain to yield some nocturnal shower chances across northern Utah and southwest Wyoming. On Sunday a trough will advance towards the region while a cutoff low remains more or less positioned near the southern California coast. While a brief period of transient ridging may be realized early, sufficient moisture in combination with the approaching trough looks to trigger shower and thunderstorm development through the day. With mean SBCAPE increasing across the northern half of the forecast region and a bit more deep layer wind shear, wouldn't be surprised to see a more organized updraft or two develop. Sunday evening into the overnight hours the trough will push a frontal boundary southward into the area. As such, may see a bit more linear/organized feature try to develop along this boundary as it pushes in, and will actually see precipitation chances increase. Moisture will begin to decrease from west to east through the day Monday as the trough starts to cut off near the UT/WY border. In turn, isolated to scattered convective chances become more focused along/east of Utah's high terrain. Otherwise, biggest noticeable change to weather will be in the form of a cooldown on the order of several degrees at areas behind the front. Anticipate afternoon highs around 3-7F below normal at these locations, which translates to mid 60s across SW WY and low to mid 70s across much of the Wasatch Front. .LONG TERM (After 00Z Tuesday/6 PM Monday), Issued 421 AM MDT... Increased dry, northerly flow aloft associated with a grazing shortwave trough will result in temperatures dropping several degrees below seasonal normals across northern Utah and southwest Wyoming on Monday. Otherwise, relatively benign and seasonable weather is expected areawide through Tuesday as a drier airmass overspreads the region. The aforementioned trough continues to move eastward out of the region on Tuesday, eventually phasing into a longwave trough over the MS River Valley. Our area becomes wedged between this feature and a closed low off the coast of southern California mid-week. The forecast becomes quite uncertain Wednesday onward given the model discrepancies in the track of the closed low. Ensembles are in a roughly 50/50 split on potential scenarios. One solution takes the low inland Wednesday into Thursday, bringing with it tropical moisture that would support wetter weather returning as early as Wednesday. The other solution keeps this low offshore until late Thursday, before moving inland on Friday. This solution would keep us drier on Wednesday and Thursday, with better chances for showers and storms on Friday into the weekend. && .AVIATION...KSLC...VFR conditions will persist for the KSLC terminal through the period. Convection, mostly tied to the terrain, will gradually diminish through the evening with isolated showers overnight. These showers will interrupt the diurnal winds before predominant southerly flow sets up overnight. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist for the airspace through the period. Terrain-driven diurnal convection across the north could briefly impact a terminal with some gusty outflow winds or lightning. These will gradually diminish overnight with isolated showers remaining possible overnight. Overall, winds will be light and diurnally driven. && .FIRE WEATHER...The influence of a lingering upper level disturbance along with ample moisture is resulting in scattered showers and thunderstorms, especially across northern Utah. Given continued support through the overnight hours, some chance of nocturnal showers and a thunderstorm or two will persist. A similar convective evolution is expected Sunday, with morning activity becoming increasingly convective in nature, primarily across northern Utah where moisture and forcing for ascent will be maximized. Late Sunday evening into the overnight hours a cold frontal boundary will drop southward into Utah. This will maintain precipitation chances overnight, with potential for more of a linear type of storm mode to form along the boundary. Following the passage of the front, temperatures cool markedly. The airmass will also begin to dry from west to east, with precipitation chances Monday becoming increasingly focused along/east of Utah's high terrain. Drier and less active conditions are expected to settle in through the middle of the week as high pressure becomes more favored. While lower confidence is noted in specifics at this time, models then suggest moisture will return with a slow moving cutoff system advancing into the region late in the work week into the weekend. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && SHORT TERM...Warthen LONG TERM...Whitlam AVIATION...Mahan FIRE WEATHER...Warthen For more information from NOAA's National Weather Service visit... http://weather.gov/saltlakecity
The Salt Lake City radar (KMTX), 156 km away, was scanning. The volume nearest the first event began at 00:40 UTC.
3 thunderstorm wind. Local standard time, as filed.
The CAUSEWAY mesonet station recorded a wind gust of 62 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The I-80 at MP 71 East Delle mesonet station recorded a wind gust of 63 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
The Hansel Valley mesonet station recorded a wind gust of 59 mph as a result of outflow winds associated with a nearby cluster of showers and thunderstorms moving through the area.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Utah in 2025Every state in 2025This day in weather historyWarnings in Utah, September 2025
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: 1286153, 1286154, 1286155.