Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
255 FXUS65 KSLC 212258 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 358 PM MST Fri Nov 21 2025 .SYNOPSIS...Potential for dense fog development exists once again tonight across northern Utah valleys and Uinta County, WY. Otherwise, quiescent conditions expected areawide through the weekend, save for light precipitation over far southeast Utah on Sunday. && .DISCUSSION...Key Points: - Dense fog is possible once again tonight across northern Utah valleys and Uinta County, WY. - Dry conditions expected areawide through the weekend, except for southeast Utah where a system passing through the Four Corners will bring light rain/high elevation snow. - A cold front passage late Monday brings much cooler temperatures on Tuesday, with the season`s first freeze possible for Lower Washington County. Mid-level water vapor imagery this afternoon depicts a closed low currently centered off the coast of far southern California, with some associated moisture wrapping into southwest Utah. Some light, isolated showers are noted across the high terrain as a result. This shower activity is expected to taper this evening as the low digs further south off the Baja coast into early Saturday. Across northern Utah and southwest Wyoming, dense fog will be a concern once again tonight for valley locations as dew points remain elevated with clearing skies. Exact locations of fog development are a bit more uncertain compared to last night, given low cloud cover has lingered longer than expected across some areas including the Cache Valley and portions of the Wasatch Back. Any fog that develops overnight into Saturday morning will be capable of producing visibility reductions to less than a quarter mile at times. After another mostly dry day regionwide on Saturday, the aforementioned low will eject inland and track across the Four Corners region on Sunday. This system will bring increased chances for precipitation across southeast Utah -- though, given that the region will remain on the fringes of greatest moisture transport, total accumulations are expected to remain generally light, generally a few hundredths of an inch of less. Locally higher amounts up to a tenth of an inch are possible in the higher terrain across south-central Utah. After the upper-level low exits the region late Sunday, a shortwave trough is slated to track to our north across the Northern Rockies late Monday. A dry cold front passage across Utah and southwest Wyoming will accompany this system, yielding much cooler temperatures regionwide by Tuesday morning. Lows for lower valleys across central and northern Utah are expected to dip into the mid to upper 20s, with the Wasatch Back and southwest Wyoming seeing lows in the teens. For lower Washington County, lows in the mid to upper 30s are expected on Tuesday. Northerly winds behind the front Monday night into Tuesday morning may yield gap winds across lower Washington County, notably areas near the Black Ridge Canyon, which will keep temperatures a bit more moderated in these areas. Wednesday morning will trend even cooler for lower Washington County as winds ease overnight, with a 20-40% chance to reach freezing. && .AVIATION...KSLC...Predominantly VFR conditions are expected through the TAF period, with northwest winds switching back to southeast around 03Z. After 06Z there is a 20% chance for dense fog developing across the airfield reducing visibility to less than 1/2 mile. Any fog which does develop will dissipate by 16Z Saturday. .REST OF UTAH AND SOUTHWEST WYOMING...Pockets of MVFR cigs will persist through the remainder of the afternoon across northern Utah and southwest Wyoming while VFR conditions prevail elsewhere. After 04Z this evening patchy dense fog will redevelop across northern Utah and southwest Wyoming, potentially resulting in LIFR to VLIFR conditions with visibility less than 1/4 mile at area terminals. Any fog which develops will persist through at least mid-morning Saturday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ PUBLIC...Whitlam AVIATION...Seaman For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity