Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
392 FXUS65 KSLC 072130 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 330 PM MDT Tue Oct 7 2025 .SYNOPSIS...Dry and generally calm conditions hold through Wednesday. Tropical moisture will start to increase by Thursday and result in enhanced precipitation chances into the weekend. A cold front will then move through later Saturday into Sunday and bring cooler temperatures along with some high elevation snow. && Key Points: - A substantial increase in moisture is expected from Thursday on into the weekend as tropical remnants brush through the region. Periods of moderate to heavy rain will lead to a threat of flash flooding, particularly for rain sensitive areas. - A deepening Pacific system will push a strong cold front through the area around late Saturday to early Sunday. In addition to bringing much cooler temperatures, it will allow for a period of high elevation snow (generally above 8000 ft). - Models show some potential for another system around the middle of the upcoming week. However, a great deal of uncertainty is noted run to run and model to model, thus certainty in more specific details is quite limited at this time. .DISCUSSION...A quiet weather day is unfolding across the forecast region this afternoon. Afternoon visible satellite loop shows little more than a cloud or two developing across some of the northern high terrain, but nothing really of note. Temperatures remain fairly seasonable, generally +/- 5F of climatological normal for this time of year. A similarly quiet day is expected on Wednesday, though increasing deep southwesterly flow ahead of a deepening Pacific system will bring warming temperatures and some modestly gusty winds. Thursday looks to be the first day in a more active forecast period as moisture associated with Tropical Cyclone Priscilla begins to lift into the region. Precipitation chances will initially increase across southern Utah, with chances quickly increasing at areas further north as moisture continues to increase. This moisture looks to become maximized Friday and Saturday, with ensemble PWAT values pushing into the 200-300% of normal range. This highly anomalous moisture will support showers and thunderstorms capable of efficient rainfall production, especially where locally higher pockets of instability can develop throughout the day(s). General model consensus favors southern to eastern Utah in terms of highest available moisture and precipitation chances, though chances will be quite elevated areawide as this moisture lingers. Given the impressive moisture, chances of excessive rainfall are noted Thursday through Saturday. This excessive rain/flash flood threat will especially be noted for rain sensitive areas such as recent burn scars, slot canyons, typically dry washes, and slickrock areas. Additionally, some increase in deep layer shear is expected as a Pacific system deepens into the western U.S., especially Saturday, and as such a few storms could be on the stronger side (pending how much instability is ultimately available). Models continue to then generally support the Pacific system sliding eastward, in turn pushing a cold frontal boundary late Saturday afternoon to early Sunday. Given the extra dynamic support from this Pacific trough and the ample moisture courtesy of the remnant tropical system, the front will have potential to be accompanied by a period of moderate to heavy rainfall, maintaining the threat of locally excessive rainfall. Snow levels will also drop quickly following the passage of the cold front, falling to around 7500-8500 ft by Sunday morning. Moisture will be decreasing by this time, but models do show potential for some light high elevation snow before moisture fully scours out. Colder temperatures will be maintained Sunday into early in the upcoming week following the passage of the cold front. Some modest amount of lingering moisture will maintain isolated high elevation precipitation chances given the core of the system moving overhead, but in general precipitation chances will be much lower than the days prior. Models then show some potential for another system moving towards the middle of the week, though there is fairly significant spread in terms of whether this system would be more progressive in nature or cut off, and in the latter scenario where exactly it would cut off. && .AVIATION...KSLC...VFR conditions with typical diurnal wind shifts are expected at KSLC through the TAF period. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions with diurnally driven wind patterns are expected at all TAF sites through the period. && .FIRE WEATHER...A dry and stable air mass is currently serving as the primary influence to weather across Utah. A Pacific system will start to deepen through midweek, resulting to a corresponding increase to deeper southwesterly flow, and in turn lead to some modest daytime wind gusts generally in the 20-30 mph range. This may result in some localized areas of elevated fire weather conditions where fuels remain sufficiently dry. On Thursday, moisture associated with Tropical Cyclone Priscilla will start lifting northward into the area. Precipitation chances in turn increase, initially for southern Utah, with chances quickly spreading northward as moisture further increases. This moisture becomes maximized Friday and Saturday, which will lead to widespread chances of wetting rainfall. The aforementioned Pacific system will then move inland, pushing a cold front through Utah late Saturday into early Sunday. This will likely be accompanied by another period of heavier precipitation, and will usher in much colder temperatures in its wake. As snow levels drop, some high elevation snow (generally above 8000 ft) will be possible into early Sunday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ PUBLIC...Warthen AVIATION...Seaman FIRE WEATHER...Warthen For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity