textproduct: Salt Lake City

KEY MESSAGES, Issued 1033 PM MDT Tue Aug 18 2026

- Building high pressure will bring a steady warming trend in temperatures through Thursday as conditions dry.

- Monsoon moisture will move back into Utah and southwest Wyoming late in the week, persisting through at least early next week. This will bring an increased threat of showers and thunderstorms capable of producing flash flooding.

DISCUSSION, Issued 1033 PM MDT Tue Aug 18 2026

High pressure centered over western AZ tonight through Wednesday will maintain an dry west-northwest flow over UT. Latest analysis shows around 0.8-0.9 inches of PWAT across the area. This should be enough to result in isolated to widely scattered diurnal and mostly terrain-based showers and thunderstorms.

The high pressure will gradually shift east towards CO/NM by Friday, and a bit farther east for the weekend. This will bring a gradual return of monsoonal moisture to the area, with showers and thunderstorms increasing over the mountains and southern Utah Thursday before becoming more widespread over the forecast area Friday through at least the early part of next week. With the increased coverage of thunderstorms and arrival of deeper moisture coupled with added dynamics from a series of weak disturbances crossing the area, the threat of flash flooding will increase during this timeframe. A Marginal Risk of Excessive Rainfall begins as soon as Thursday across portions southern Utah and will be more widespread across the area by Saturday.

With the arrival of the deeper moisture, temperatures will trend downward towards the end of the week into next week. Until then, however, temperatures will remain on the warm side, with highs around 5-10 degrees above normal. The NBM currently has a 25-30% chance of SLC reaching 100F Thursday-Friday. However, with the warm bias commonly exhibited locally by the NBM in the warm season, suspect that the chance of reaching 100F is much higher, especially on Thursday, so have adjusted temperatures to reflect this thinking. HeatRisk also falls into the Red (Major) category in many valley areas on Thursday, but the increased threat of heat related illness will be mitigated due to overall acclimation during the season.

AVIATION

KSLC...Generally light southeasterly winds prevail this morning, but may become variable at times, especially between 12-16z. Winds are expected to transition to the northwest after around 18z. VFR conditions prevail at the terminal through the period, with continued FEW-SCT mid to high level cloud coverage.

REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions prevail for all regional terminals through the period. Isolated showers and thunderstorms are expected across portions of southeast Utah this afternoon and evening, with potential to produce gusty and erratic outflow winds. Otherwise, winds remain generally light and diurnally driven across the rest of the airspace.

FIRE WEATHER, Issued 442 AM MDT Wed Aug 19 2026

High pressure continues to strengthen across the region through Thursday, resulting in temperatures warming around 10 degrees above average through this period. This pattern will also favor continued near critical to critically dry conditions for lower elevations across the state. Isolated showers and thunderstorms are expected to develop each afternoon through Thursday, remaining mostly dry with threats for gusty and erratic outflow winds and dry lightning strikes. Moist, southerly flow develops on Friday across the region and continues through the weekend, resulting in gradually increasing RH values areawide in addition to wetter storms capable of producing heavy rainfall and flash flooding.

SLC WATCHES/WARNINGS/ADVISORIES

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