Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
946 FXUS65 KSLC 291018 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 418 AM MDT Fri Aug 29 2025 .SYNOPSIS...A remnant tropical system will continue to impact mainly southern through eastern Utah through Friday morning. Thereafter, expect a general drying and warming trend this weekend into early next week. && .SHORT TERM (THROUGH 12Z SUNDAY)...Remnants of a tropical system will continue to eject across southwest through east-central Utah this morning. This is associated with increased moisture, with precipitation filling in across southern Utah late last evening and overnight. Latest analysis shows PWATs of around 1.1 inches currently across far southern Utah, and around 0.8-0.9 inches across western and central Utah. As this feature exits the area this afternoon, the airmass will gradually trend drier. The precipitation thus far has been in the form of generally light stratiform rain, with some areas seeing briefly moderate rates. Radar estimates of precipitation vary quite significantly depending on the methodology, but observations from precipitation gages have been more in line with the lower values (generally less than a third of an inch over the past 6 hours). Even so, there remains some hydrologic concerns for some of the more sensitive basins, especially heading into the morning hours as the lower levels have become more moist compared to earlier in the night. By this afternoon, the widespread stratiform rain is expected to have mostly exited to the east. Lingering moisture will allow some convection to develop behind it, most likely across central and portions of northern Utah, as southern Utah may be a bit suppressed behind the weather system. Afternoon convective coverage is expected to be mostly isolated to scattered but some of the stronger storms may be capable of producing brief moderate rain. As the airmass continues to dry, afternoon convection tomorrow will be much more limited and generally weaker, resulting in greatly reduced chances of significant precipitation. Meanwhile, temperatures, while gradually trending warmer, will continue to remain below climatological normals through Saturday. .LONG TERM (After 12Z/6AM Sunday)...The long-term period will be much drier and quieter than this past week as high pressure continues to build. With the ridge axis overhead, expect light winds and largely quiescent weather, with temperatures warming an additional few degrees by Sunday. Despite this drier air mass, a few isolated showers are possible Sunday and Monday afternoons across the southern mountains, owing to PWATs still around 80-90% of normal combined with solar insolation. Models continue to highlight the potential for a marginal increase in moisture by mid-week, though uncertainty in the spatial extent and magnitude still remains. The 25th percentile of ensemble members actually still suggests little to no increase in moisture (except maybe in St. George)...with the 75th percentile favoring an increase across mainly southern Utah. At this time, the main threat appears to be dry microbursts given overall limited moisture, though we`ll need to monitor the chances for isolated flash flooding if the wetter solution pans out. && .AVIATION...KSLC...Light, southeasterly winds will continue through the morning, transitioning to northwesterly around 17-19z. Isolated showers and thunderstorms will develop after ~19z over nearby higher terrain, with a low chance of impacting KSLC directly (20% chance). If a storm does move over the terminal, the main threats would be gusty and erratic outflow winds and lightning. .REST OF UTAH AND SOUTHWEST WYOMING...A large swath of light, stratiform rainfall continues to move into southern Utah early this morning, though conditions are likely to remain VFR despite rainfall lasting through the morning hours. This area of rainfall will continue northeastward through the early morning, reaching KPUC around 10z and KU69 as early as 12z. Across areas that did not experience this rainfall, including areas west of KPVU-KHCR-KEVW and north of KDTA, scattered showers and isolated thunderstorms are expected to develop after ~18-19z. These showers may be capable of producing gusty and erratic outflow winds. && .FIRE WEATHER...A brief increase in moisture associated with the remnants of a tropical system will continue to bring widespread, mostly light to occasionally moderate rain across southern through east-central Utah this morning. As this system moves out of the area during the afternoon, the airmass will slowly trend drier again. However, enough moisture will linger to produce isolated to scattered showers and thunderstorms over the area this afternoon, with some of the stronger storms capable of producing wetting rain. The drying trend will then continue through the weekend into the beginning of next week, with precipitation becoming much more limited. During this drying trend, relative humidities will trend downward, with afternoon mins into the mid to low teens in many valley areas by Sunday and Monday. Temperatures will also trend warmer, but afternoon maxes only reach climatological normals by Sunday. Moisture looks to increase again Tuesday or Wednesday, but not significantly. This will result in increased chances for showers and thunderstorms, but wetting rain chances look to remain low at this time. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Cheng/Cunningham For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity