388 FXUS65 KSLC 222140 AFDSLCArea Forecast Discussion National Weather Service Salt Lake City UT 340 PM MDT Mon Sep 22 2025
.SYNOPSIS...Following todays unsettled pattern, benign conditions develop as ridging persists through the next few days. Chances for rain return across at least southern UT as early as Thursday.
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.DISCUSSION... Key Messages: * Scattered showers and thunderstorms persist over eastern UT and southwest WY this afternoon before a drier pattern takes hold through at least midweek. * For snow lovers, some snowfall has been observed across the high Uintas this afternoon and is expected to persist through the evening. * Minimally impactful canyon winds appear possible tomorrow morning for Washington, Davis, and Weber county canyons. Another chance for morning canyon winds across the aforementioned areas exists Wednesday morning. * Below normal temperatures are forecast tomorrow across the forecast area before temperatures rebound to near-normal Wednesday through the weekend. * Chances for rain return for southern UT on Friday as moisture advects north into UT.
Currently, showers and thunderstorms are ongoing across the high terrain of central UT and the Uinta basin with lingering moisture sparking isolated showers across northern UT and SW WY. Following this activity, an omega block is forecast to develop over the western U.S. as troughing prevails over the eastern U.S., a ridge develops over much of the interior western U.S., and a cutoff low meanders off the south-central CA coastline. This is expected to bring dry and benign conditions to the forecast area through at least Wednesday. Temperatures tomorrow will remain slightly below normal before heights increase on Wednesday which will serve to raise temperatures across the forecast area to near normal through the weekend. Canyon winds across northern UT, particularly canyons across Davis and Weber county, may see canyon winds early tomorrow morning and Wednesday morning as easterly winds develop over the Wasatch. Additionally, northeasterly winds will develop across Washington county tomorrow morning, and perhaps Wednesday morning, resulting in canyon winds as well.
Come Thursday, enhanced flow within the northern stream will begin to erode the northern edge of the aforementioned ridge. This will serve to weaken the ridge with a slight eastward movement as it attempts to phase into the mean flow to the north. As a result, the aforementioned cutoff low will begin to slide east across southern CA into western AZ/southern NV with UT sitting along its northeastern periphery. As a result, south-southeasterly winds will translate to the surface and overspread the area. This is where the forecast begins to diverge somewhat as more moving parts are added. Ensemble guidance still remains foggy on the exact positioning of the low to our southwest, where we would want the low further east for the best chances of rain across southern UT and perhaps the northern half of the forecast area. Second, tropical storm Narda will be churning southwest of southern CA which could incorporate more moisture into this setup depending on the position of Narda in a few days.
Omega blocks typically yield some uncertainty with forecasting in the extended, and adding a tropical system to the forecast doesn`t make the waters any less muddy. Cluster analysis has began to come closer to agreement within the ensemble suites with ~70% of all ensembles (GFS, EURO, Canadian) with the low situated somewhere along far southern NV to southwest CA which would put us in a favorable pattern for rainfall across southern UT. Although, 30% of ensembles push the low off to the east much faster which would likely inhibit the amount of moisture that is advected north into the CWA. While confidence has increased somewhat, there are still some caveats that need ironed out. Regardless, a pattern shift for at least southern UT appears on tap as we approach the end of the work week.
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.AVIATION...KSLC...VFR conditions will persist for the KSLC terminal tonight and tomorrow. There is a very low chance (less than 20%) for vicinity showers this afternoon, otherwise clearing skies are expected this evening and persisting through tomorrow. Light northwest winds will persist through the evening and into the overnight hours, with a low chance (20-40%) of persisting all through the night. Otherwise, expect light southeast winds to develop overnight.
.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will persist for the airspace through the period in the wake of a passing front (currently stretching from KPUC to K74V and quickly moving eastward). Areas ahead of and along the front will see scattered showers with isolated MVFR cigs/vsbys in heavier precipitation. Behind the front, a few cumulus and isolated showers will die off after sunset, allowing for calm and clear conditions overnight.
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.FIRE WEATHER...Storms are ongoing across the high terrain of central UT and the Uinta Basin which are expected to clear the area this evening. Following this, high pressure builds into the area which will result in a dry pattern across UT through at least Wednesday. Tomorrows temperatures will start below normal before we see a gradual warm up to near normal temperatures by midweek. On Thursday, there is a signal for a pattern change as low pressure moves by to our south which could push moisture up into UT once again raising humidities and increasing chances for rain. There is some uncertainty surrounding this regarding the track of the low, but there is good agreement that precipitation appears possible across southern UT starting Thursday through the weekend.
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.SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. &&
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PUBLIC...Worster AVIATION...VanCleave FIRE WEATHER...Worster
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NWS SLC Office Area Forecast Discussion