textproduct: Salt Lake City

KEY MESSAGES, Issued 1018 PM MDT Thu Aug 20 2026

- Hot temperatures will persist over the valleys of northern Utah Friday, with low temperatures in the mid to upper 70s providing little overnight recovery.

- Monsoonal moisture will surge into Utah and southwest Wyoming Friday and Saturday, bringing an increased threat of thunderstorms producing heavy rainfall and flash flooding.

- Moisture is expected to decrease from Sunday through Tuesday, bringing less coverage of showers and thunderstorms and lower potential for heavy rainfall early next week and beyond.

DISCUSSION

Late morning and afternoon satellite imagery reveals a broad veil of cloud cover moving across central and northern Utah with far southern and eastern Utah remaining largely cloud free. Within this area of enhanced cloud cover, isolated thunderstorms are developing, owing to the increased atmospheric moisture and instability building into the region. For the northern and central portions of the forecast area, shower and thunderstorm coverage is expected to increase through the afternoon as the shortwave leading the influx of moisture continues north. The subsident wake of this wave, however, is likely to limit the amount of convection and storm development that we see across the southern area. This is the biggest change with the forecast today. As such, while thunderstorms producing heavy rainfall and increased flash flood potential are still expected in southern Utah, the coverage of such will be much less than previously forecast. This threat is now transitioning into central Utah, as well as a portion of northern Utah. In northwest Utah where sufficient surface moisture is lacking, any storms developing will carry potential for strong outflow winds in excess of 40 mph.

This wave of energy will exit the region through Saturday, placing much of the forecast area under a subsident wake. While atmospheric moisture will be elevated, the areawide subsidence will help to inhibit widespread shower and thunderstorm coverage. Again, while coverage is not expected to be as widespread as previously thought, any storms that do develop will carry higher than normal potential of heavy rainfall. If these storms end up over a particularly sensitive area (slot canyons, recent burn scars, urbanized areas, etc.) then the threat of flash flooding will be elevated.

The increase in areawide moisture will help to moderate temperatures as we head through the weekend, with most areas outside of lower Washington County expected to fall below triple digit territory. Models have been consistent with the support of a drying atmosphere from Sunday forward, which will allow for lower coverage of showers and thunderstorms across Utah and southwest Wyoming, as well as a decreasing risk of flash flooding into early next week. Dry conditions look to be maintained from roughly Wednesday forward as moisture vacates the region and high pressure remains in place.

AVIATION...KSLC

Scattered showers and thunderstorms developing south and east of the terminal early this afternoon will bring a chance of lightning and strong outflow winds in excess of 40 KTS during the 23-02Z timeframe. Away from thunderstorms, VFR conditions with southerly winds will prevail through the afternoon and evening.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and thunderstorms will bring a chance for lightning and strong outflow winds in excess of 40 kts to northern terminals through 03Z this evening. Isolated showers and thunderstorms are possible further south near KCDC and KSGU. Away from any thunderstorms, VFR conditions can be expected through the TAF period with southerly winds this afternoon becoming terrain driven this evening.

FIRE WEATHER

Hot temperatures remain in place across the area today, with dry conditions expected in northwest and eastern Utah while southwest Utah sees an increase in moisture. With the increase in moisture across the southern half of Utah, afternoon shower and thunderstorm development is expected through the remainder of today with storms bringing potential for wetting rains. Coverage of showers and thunderstorms will be greatest across central and northern Utah, however, wetting rain potential will decrease north of the US-50/ I-70 corridor. The bigger threat for central and northern Utah will be isolated dry lightning and gusty outflow winds in excess of 35-40 mph. These strong winds and dry surface conditions may bring short-lived critical fire weather conditions.

Moisture will continue to push northward on Saturday, bringing improvement to afternoon humidity across the northern and central area while the southern area will see the beginning of a slow drying trend. That said, shower and thunderstorm potential will still be elevated over the high terrain features throughout Utah over the weekend, however, the chances for wetting rains will sharply decrease. Moisture will gradually decrease areawide each day from Sunday through Tuesday next week, with decreasing coverage of precipitation expected alongside a drying surface humidity trend. By Wednesday, widespread humidity at, or below, 15 percent is anticipated to be maintained through the remainder of the week.

SLC WATCHES/WARNINGS/ADVISORIES

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

WY...None.