Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
286 FXUS65 KSLC 202255 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 355 PM MST Thu Nov 20 2025 .SYNOPSIS...There is potential for fog development across the Cache Valley and portions of the northern Wasatch Front tonight into early Friday morning. An active pattern continues into the weekend as a couple upper- level lows impact the region. && .DISCUSSION...Key Points: - Valley rain and high elevation snow showers ongoing this afternoon across the area are expected to taper off tonight. - Saturated soils from today`s rainfall will bring potential for fog developing across the Cache Valley and portions of the Wasatch Front tonight into Friday morning. - An upper-level low tracking through the Four Corners region this weekend brings chances for precipitation late Saturday and Sunday. Current radar imagery depicts scattered valley rain and high elevation snow showers ongoing across much of northern and eastern Utah, with more isolated coverage across high terrain of central Utah. These showers are associated with moisture wrapping around an upper- level low centered across central New Mexico, with showers exhibiting a north-to-northwesterly motion as a result. Activity is expected to taper this evening and into the overnight hours as the low continues to eject northeastward into the Central Plains, cutting off additional moisture transport into our region. Before precipitation tapers tonight, expect periods of wintery conditions on some northern Utah mountain passes this afternoon and evening under heavier showers. Rainfall that has occurred across northern Utah valleys this morning and afternoon will set the stage for radiation fog to develop overnight as moist soils and relatively high dew points will be in place. The areas with best chances to see widespread dense fog tonight include those which saw fog development last night, notably the Cache Valley and eastern Box Elder County. Portions of the Wasatch Front also come into play tonight for more patchy fog development, especially areas from the Salt Lake Valley northward. Any fog that develops will be capable of dropping visibility to a half- or quarter-mile late tonight into Friday morning. Another upper-level low currently dropping down the coast of Southern California is expected to eject inland and cross the Four Corners region late Saturday into Sunday, bringing increased chances for precipitation across southern Utah. 70% of ensembles are favoring a more southern track of this low, which would bring limited accumulations, anywhere from nothing to a few hundredths of an inch. The other 30% of ensembles favor a slightly more northerly track, but accumulations still appear relatively meager with this scenario, with 0.1-0.2" of precipitation for lower elevations and 0.25-0.3" for mountain locations. The remainder of the region is expected to remain dry and mild this weekend as high pressure remains the dominant feature. The upstream pattern remains progressive early next week as a shortwave entering the Pacific Northwest on Monday slides eastward across the Northern Plains through Tuesday. While this isn`t expected to bring any notable precipitation through this period, temperatures may cool upwards of 5-10 degrees across northern Utah and southwest Wyoming behind a dry cold front passage associated with this system depending on the progression of this system. && .AVIATION...KSLC...Scattered rain showers in the area will largely diminish by 00z, with brief periods of MVFR VIS and mountain obscuration possible. Northwest winds will lighten through the evening and become primarily southeasterly or even light and VRB by 04-05z. There is a heightened chance for dense fog development overnight and into the early morning hours, with a least low-end MVFR conditions expected to develop (70% chance of MVFR or less between 09-15z). Dense fog development will depend on how much mid- to high-level clouds scatter out overnight. Currently, expect a 40% chance of dense fog/LIFR conditions, with the best chances between 11-15z. .REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers will gradually diminish by 03z in most areas, though areas between KEVW- KHCR may see lingering showers through 07z. Winds will be fairly light and variable overnight, and coupled with recent precipitation and breaks in the clouds developing overnight, this will produce areas of dense fog/LIFR conditions across many valleys overnight (particular N-UT/SW-WY). This is dependent on how much clouds are able to scatter out, as clearer skies will likely result in more widespread fog for a longer duration. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ PUBLIC...Whitlam AVIATION...Cunningham For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity