textproduct: Salt Lake City

KEY MESSAGES

- An influx of smoke originating from numerous fires across the Pacific Northwest will continue through at least Thursday.

- Widespread dangerous heat develops across southern Utah on Thursday, then becomes more widespread across the remainder of Utah Friday into Saturday.

- Showers and thunderstorms capable of producing microburst winds are expected each afternoon Thursday into the weekend, mainly across southwest Utah.

- Monsoon moisture spreads northward Sunday into early next week, resulting in more widespread storms capable of producing isolated flash flooding.

DISCUSSION

Recent satellite imagery shows smoke from fires across the Pacific Northwest lingering across central and northern Utah and southwest Wyoming this afternoon. Westerly flow developing on the northern fringe of a strengthening high pressure ridge is expected to scour some of this smoke out of northern Utah overnight, but some haze may linger into Thursday. Across central Utah, the Widemouth 2 Fire continues to output high concentrations of near surface smoke. This fire will continue to impact surrounding areas while it remains active, but more efficient mixing on Thursday will keep the impact footprint smaller as smoke becomes more vertically integrated into the atmosphere.

The aforementioned ridge will continue to amplify over the Great Basin through Saturday, resulting in temperatures climbing well above average through this period. High temperatures peak on Saturday, with highs around 10 degrees above average. Low temperatures gradually increase through the weekend as well, with the Wasatch Front and lower Washington County seeing exacerbated heat impacts as a result. Given this, Extreme Heat Warnings were issued for most southern Utah valleys Thursday through Saturday, and the Wasatch Front, Great Salt Lake Desert, and Castle Country/San Rafael Swell through Sunday. Heat Advisories are in effect for all other valleys across the state.

Intense heating under this anomalous ridge will result in increased chances for afternoon showers and thunderstorms, mainly across southwest Utah, beginning Thursday. Chances for afternoon convective development will continue through the weekend, with the main impact from storms through Saturday being dry lightning and gusty and erratic outflow winds, given dry lower levels through this period. The ridge shifts eastward Sunday, introducing a more favorable southerly flow pattern for monsoon moisture to spread into the region through early next week. Storms will transition wetter by Sunday across southwest Utah, with coverage expanding northward into early next week as moisture continues to spread north. The potential for wetter storms on Sunday raises concerns for locally heavy rainfall to produce flash flooding, especially for slot canyons, recent burn scars, and normally dry washes.

AVIATION, Issued 1116 AM MDT Wed Aug 5 2026

KSLC...Northwesterly winds will prevail through the afternoon, transitioning to southeasterly between 03-04z. VFR conditions will mostly persist outside of a window around sunset and sunrise where wildfire smoke may produce slantwise VIS reductions down to MVFR for an hour or two.

REST OF UTAH AND SOUTHWEST WYOMING...Winds will largely be light and terrain-driven, though eastern Utah this afternoon will favor breezy westerly winds with gusts to 20-25kts. VFR conditions will largely persist with hazy skies, though lingering wildfire smoke could produce slantwise VIS reductions down to MVFR across central/northern Utah. Sites near local wildfires could see further reductions.

FIRE WEATHER

Dry conditions continue statewide with widespread relative humidity values in the single digits to low teens and poor overnight recoveries through Saturday, courtesy of strengthening high pressure across the western US. This pattern will also result in a warming trend through Saturday, with temperatures climbing around 10 degrees above average by Friday. Intense heating will yield increasing chances for afternoon showers and thunderstorms beginning Thursday and continuing into the weekend, mainly across southern Utah. Storms will be on the drier side between Thursday and Saturday, with main threats being dry lightning and gusty and erratic outflow winds to 50 mph. A modest surge of monsoon moisture is expected Sunday into early next week, and as such coverage of storms expands northward with better potential across southern Utah for storms to produce locally heavy rainfall.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Extreme Heat Warning from noon Friday to midnight MDT Sunday night for UTZ101-102-104-105-115-120-121.

Heat Advisory from noon Friday to midnight MDT Sunday night for UTZ103-106-107-114-116.

Heat Advisory from noon Thursday to 9 PM MDT Saturday for UTZ118- 119-122-126-127.

Extreme Heat Warning from noon Thursday to 9 PM MDT Saturday for UTZ123-124-128>131.

WY...Red Flag Warning until 9 PM MDT this evening for WYZ277.