textproduct: Salt Lake City

KEY MESSAGES, Issued 136 PM MDT Thu Aug 20 2026

- Strong high pressure will bring hot temperatures to much of Utah on Thursday and Friday, especially across northern and central Utah where little relief from heat is expected.

- Monsoonal moisture will surge into Utah and southwest Wyoming Friday and Saturday, persisting through at least early next week. This will bring an increased threat of showers and thunderstorms capable of producing flash flooding.

DISCUSSION, Issued 136 PM MDT Thu Aug 20 2026

Minor, but noteworthy increases in atmospheric moisture and instability are noted across the region today as afternoon satellite and radar imagery reveal isolated showers and thunderstorms spread across the high terrain features of Utah. That said, early afternoon mesoanalysis shows a finger of elevated (1+ inch) PWAT values just barely sneaking into far southwest Utah. Therefore, it appears the current environment is only supportive of isolated heavy rainfall with slower moving storms. Additionally, with a ridge of high pressure cresting over the region today, heat is also expected to maximize across the region with high temperatures on the Wasatch Front, and other western valley areas, around 100 degrees. With overnight lows in this region only expected to recover to around 70 to 75 degrees, prolonged exposure to the heat may bring an increased risk for heat related illness in vulnerable populations. This heat is expected to remain in place across northern Utah on Friday while waning across central and southern Utah.

The center of the high pressure will shift into the Four Corners region on Friday, aiding in the advection of monsoonal moisture into southern and central Utah. As such, the coverage of showers and thunderstorms will expand farther north on Friday afternoon, with similar risks of heavy rainfall and flash flooding expanding into southern and central Utah. Particular areas of concern for flash flooding will be recent burn scars, slot canyons, dry washes, and steep terrain.

The position of the high will shift farther east on Saturday, altering the trajectory of the moisture plume into northern Utah and southwest Wyoming, thus expanding the threat of showers and thunderstorms capable of producing heavy rainfall and flash flooding. Models do indicate a dry slot working into southwest and west-central Utah on Saturday and Sunday, which may act to limit storm potential in this region of Utah while areas in the north see an increase in coverage. The position of the high goes relatively unchanged through early next week, bringing daily shower and thunderstorm coverage over the high terrain features of Utah, as well as potential for heavy rainfall and flash flooding to typically prone areas.

AVIATION

KSLC...The SLC terminal will see VFR conditions through the overnight hours with some scattered clouds. Northwest winds are expected to return to the south between 03Z and 05Z with tomorrow's shift to the north most likely occurring between 19Z and 21Z. With increasing moisture, there is a 30 percent chance of the terminal seeing a period of gusty and erratic thunderstorm winds, with the most likely time during the late afternoon and early evening.

REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail across the airspace through the overnight hours. Scattered showers and thunderstorms have been focused over the higher terrain and will continue into the early evening before dissipating. Any storms that develop will have the potential to produce gusty and erratic winds, lightning, and brief mountain obscurations. With moisture increasing tomorrow, coverage of showers and thunderstorms will become a bit more widespread tomorrow afternoon, with similar potential aviation impacts as today. Away from thunderstorms, generally light and terrain driven winds will prevail.

FIRE WEATHER, Issued 136 PM MDT Thu Aug 20 2026

Monsoonal moisture is expected to increase across Utah through the weekend, bringing increased coverage of showers and thunderstorms across the high terrain in the region. In addition to shower and thunderstorm activity, a trend of increasing humidity is expected areawide. That said, lower elevations of western, eastern, and southern Utah will continue to see minimum relative humidity values in the mid- to upper-teens. For the higher terrain areas, minimum values may only fall into the 25 to 35 percent range with good to excellent recovery expected areawide. While probability for wetting rains will be relatively high over the mountainous terrain (up to 45-60 percent chance), lower lying adjacent valley areas will see far lower chances (15 percent or less). On Friday in particular, developing storms will bring potential for strong outflow winds over central and northern Utah. Daily shower and thunderstorm chances will be maintained through at least Tuesday next week, with storms expected to develop over the high terrain features each afternoon.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Heat Advisory until 7 AM MDT Saturday for UTZ101>106.

Heat Advisory until 7 AM MDT Friday for UTZ115-116.

WY...None.