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, persisting through at least early next week. This will bring an increased threat of showers and thunderstorms capable of producing heavy rain that could lead to flash flooding.

DISCUSSION, Issued 1018 PM MDT Thu Aug 20 2026

High pressure is centering itself over the Four Corners region this evening, with a southerly flow developing over Utah and southwest Wyoming. Despite some drying over the past couple of days, satellite derived PW values are still predominately in the 0.7 to 0.8 inch range, more than enough for development of showers and thunderstorms over the higher terrain this afternoon, with convective activity continuing over southern Utah, including a few strong thunderstorms Short range guidance is indicating that shortwave energy moving in from Arizona should keep some showers and thunderstorms going through the first part of the overnight hours, with coverage diminishing as sunrise approaches.

Temperatures were quite hot across the valleys of northern Utah this afternoon, with most valleys seeing temperatures around 100F. Lows in the lower to mid 70s will not provide much in the way of relief, with highs in this area tomorrow expected to be similar to today. Going Heat Advisory covers this threat well.

The southerly flow that is developing will allow monsoon moisture to spread into central and southern Utah during the day Friday and into northern portions of the area Friday evening into Saturday morning. As a result, coverage of convection will be more widespread tomorrow afternoon, but given the lack of additional forcing mechanisms initially, should be focused over the higher terrain at first. Seeing evidence that some more shortwave energy from Arizona will eject northward during the late afternoon, impacting northern Utah during the evening, potentially bringing additional convection to the valleys of northern Utah.

Once the moisture is in place, there is little change in the pattern expected through early next week as confidence is high that the ridge will continue to park itself over the Four Corners. This will bring high temperatures near seasonal normals by the start of the upcoming week, with a daily threat of showers and thunderstorms that could produce heavy rain capable of flash flooding, particularly during the afternoon and early evening. As the middle of next week approaches, confidence in the pattern decreases noticeably, with a good portion of guidance showing a drying trend from the west as the ridge retrogrades over Arizona.

AVIATION

KSLC...VFR conditions will persist for the KSLC terminal through the period. Dry conditions during the day will transition to scattered convection late in the afternoon through the early evening becoming more isolated showers overnight. Winds will be light and diurnally driven except during instances of gusty and erratic outflow winds from thunderstorms.

REST OF UTAH AND SOUTHWEST WYOMING...Mostly VFR conditions will persist for the entire airspace throughout the day. Isolated to scattered convection will develop across the airspace during the afternoon and early evening with brief impacts to terminals. Gusty and erratic winds will be possible with nearby storms. Otherwise, winds will remain relatively light and diurnally driven.

FIRE WEATHER, Issued 242 AM MDT Fri Aug 21 2026

High pressure centered over the Four Corners will peak temperatures today with a gradual cooling trend through the weekend. It is also drawing up moisture into the area that will remain in place through early next week. Some dying showers remain across southwestern Utah this morning. This will remain the pattern through the weekend: showers and storms developing during the day with some storms lingering into the overnight. Where exactly these storms linger will be determined by where the heavier precipitation develops during the day.

The highest chance of precipitation will be in the mountains with significantly lower precipitation, particularly wetting rain, chances across the lower terrain where min RH will still be low in the upper teens to low 20s. Storms remain through early next week along with increasing southwesterly winds as low pressure grazes the area to the north.

SLC WATCHES/WARNINGS/ADVISORIES

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

Heat Advisory until 7 AM MDT this morning for UTZ115-116.

WY...None.