textproduct: Salt Lake City

KEY MESSAGES, Issued 1038 PM MDT Sat Sep 26 2026

- Increasing moisture aloft ahead of an approaching system will result in scattered showers and thunderstorms across southwest Wyoming, the Utah mountains, and the eastern half of Utah on Sunday.

- An upper-level disturbance moving across the Desert Southwest will draw deep tropical moisture from Hurricanes Odalys and Polo into the region Monday into Tuesday, bringing an increased risk for flash flooding across portions of southern and eastern Utah.

- Drier, more seasonable conditions develop mid-week and persist through at least Friday.

DISCUSSION, Issued 1038 PM MDT Sat Sep 26 2026

A dry southwesterly flow remains in place over Utah this evening. Upstream, an upper trough is strengthening off the PacNW coast. Meanwhile, Hurricanes Odalys and Polo continue to spin in the eastern Pacific.

The upstream trough will carve south towards the northern/central California coast on Sunday, with southwest flow continuing over Utah. Meanwhile, a weak vort lobe originating near Hurricane Odalys will become absorbed into the southwesterlies and lift across Utah during the afternoon. This weak disturbance will bring increased moisture and isolated to scattered showers and thunderstorms to Utah by Sunday afternoon, generally focused over and near the spine of Utah.

As the trough develops into a closed low over southern California and far southern Nevada on Monday, Hurricane Polo will track northeast, moving into Baja California. Moisture from the hurricane will become ingested into the southwesterly flow ahead of the closed low and increase into southern Utah. This will continue to bring the potential for widespread and locally heavy rain, especially across southern and eastern Utah as the closed low crosses from California into Arizona Monday through Tuesday.

Model QPF continues to creep up for the Monday-Tuesday timeframe, especially notable on the lower end of the probabilistic spectrum (NBM 25th percentile values now in excess of 0.6 inches for the bulk of south-central and southeast Utah), which increases confidence in wet conditions. A good portion of south-central through southeast Utah has a 60-70% chance of exceeding 1 inch Monday through Tuesday, highest along the Arizona border. Precipitation amounts will decrease farther north and east into Utah, with east-central Utah having a 60-70% chance of exceeding 0.5 inches, and areas farther north and east with a 30% chance or less.

The heavy rain will bring an increased risk of flooding/flash flooding to the area. The WPC Excessive Rainfall Outlook now has a Moderate Risk across portions of southern Utah, and the Slight Risk now extends into central and portions of northeast Utah. Although model instability is increasing, especially across southwest Utah, precipitation may well end up as largely stratiform with embedded convective elements, and the strength and coverage of these convective elements will most likely determine the extent of any significant flash flooding.

Cooler temperatures will spread into the area Monday and Tuesday, with afternoon maxes falling to around 4-10 degrees below normal and largely failing to rise above the low to mid 70s in most valleys. Temperatures will slowly rebound midweek as the storm system exits the area. There is still some model spread with regards to the large-scale pattern for the latter part of the week. Some models have been trying to bring a trough back into the area, but based on cluster analysis of global ensembles, it appears that any trough may end up being relatively weak.

AVIATION

KSLC...The SLC terminal will see VFR conditions throughout the day with some high clouds. Generally light winds are expected to become prevailing southerly by 15Z, becoming gusty this afternoon into the early evening. There is a 10-20 percent chance of outflow from showers developing east of the terminal to bring a period of gusty and erratic winds, most likely between 00Z and 04Z.

REST OF UTAH AND SOUTHWEST WYOMING...The airspace will see VFR conditions throughout the day, with southerly winds gradually increasing during the day. Some moisture will start to spread northward into the area today, bringing 20-30 percent coverage of showers and thunderstorms for the higher terrain east of I-15 late this afternoon into the early evening. Coverage of showers will increase more noticeably over southern Utah beginning Monday morning, with coverage spreading northward during the day Monday.

FIRE WEATHER, Issued 439 AM MDT Sun Sep 27 2026

A Pacific storm system will move onshore over California today. As it does, southerly winds across the area will continue to increase, particularly for western Utah where a few gusts could reach 40 mph this afternoon. The southerly winds will start to draw moisture back northward, but will stream in substantially Monday as the storm system crosses Utah, bringing much cooler temperatures as well as widespread coverage of showers and thunderstorms for the southeastern three-quarters of the state with a high chance of wetting rainfall. The system is expected to linger across the Desert Southwest Tuesday, keeping the potential for precipitation in place for southern Utah. Drier conditions are expected to move in by midweek with temperatures gradually warming to near seasonal normals.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...None.