textproduct: Salt Lake City

KEY MESSAGES, Issued 1104 PM MDT Wed Jul 8 2026

- Another round of isolated thunderstorms will develop in vicinity of I-80 tomorrow over the higher terrain, capable of producing strong outflow winds over 50 mph. - Gusty winds and low relative humidity will combine to produce areas of critical fire weather conditions during the afternoon and early evening Thursday over portions of southern Utah.

- The most significant heat wave thus far this season will develop over the weekend with high temperatures challenging daily and monthly records Saturday and Sunday. Most valleys and some mountain valleys have a greater than 60 percent chance of seeing HeatRisk values in the red (Major) range, bringing an increased chance of heat-related illnesses.

- Confidence is increasing the monsoonal moisture will move into the area by the middle of the upcoming week, though details of which days have a higher chance of flash flooding have yet to come into focus.

DISCUSSION, Issued 1104 PM MDT Wed Jul 8 2026

A slightly drier air mass will begin to make its way into the area tomorrow under southwest flow aloft, with the most notable drying over southern Utah. With lingering moisture over northern Utah and another subtle shortwave trough on track to move through during the afternoon, anticipate the development of at least a few showers and thunderstorms, though coverage will likely be a bit less than recent days.

As the airmass continues to dry and strong high pressure builds substantially over the western United States, confidence is high in temperatures across Utah and southwest Wyoming shooting up to record challenging levels for Saturday and Sunday. Guidance continues to show the center of the ridge over Utah on Saturday and just east of the area on Sunday. Guidance has, if anything, gone up with regard to the forecast compared to yesterday, with the majority of valleys and mountain valleys showing at least a 60 percent chance of red (major) HeatRisk for both Saturday and Sunday. It seems all but certain that daily temperature records will be broken, with some monthly and (in the case of the Cache Valley) all time records forecast to be broken. Given this and many valley low temperatures staying in the 70s overnight, this will predictably bring a quite increased chance of heat related illnesses over the weekend. Given the high confidence in the forecast, have gone ahead and issued an Extreme Heat Watch for all of those areas with at least a 60 percent chance of seeing HeatRisk values in the red, which includes just about all valleys (lower Washington county excluded) and many mountain valleys. As the forecast comes in clearer focus over the next couple of days, upcoming shifts will make decisions about advisories and warnings.

With southerly flow expected to increase over the area for the early and middle part of the upcoming week, models continue to indicate a high likelihood of monsoonal moisture returning to the area, bringing temperatures down and rain chances up. While this would decrease the fire danger, it brings an increased potential for flash flooding, particularly for southern Utah. The ECMWF ensemble probability of >1" of precipitable water, for example, indicates a 60-80% of that magnitude of moisture sitting over the entire Great Basin for a week or more starting next Tuesday. Details of which days have the best chance of flash flooding have yet to be ironed out, as that will likely involve timing of weak shortwave impulses (if any), which cannot be ascertained this far out in time.

AVIATION, Issued 1104 PM MDT Wed Jul 8 2026

KSLC...Scattered showers are forecast to persist at the KSLC terminal through 09z before drying out. Another round of thunderstorms may occur during the hours of 21-02z tomorrow, though confidence remains uncertain at this time regarding coverage. Northwest wind shift is expected to occur around 17z with drainage southerlies returning around 04z.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers with occasional thunder will persist through around 09z across northern UT and southwest WY before drying out. Generally diurnal wind shifts are expected across all sites through the TAF period. Additionally, chances for scattered showers and thunderstorms exists across most northern UT and southwest WY sites tomorrow afternoon from roughly 20-02z.

FIRE WEATHER

Drier air will continue to spread into the area through the rest of the week under a west to southwesterly flow aloft. Humidities will trend downward across the area and overnight recoveries will become increasingly poor, especially across central and southern Utah. Showers and thunderstorms across portions of northern and central Utah today and tomorrow will become more isolated in nature, although gusty outflow winds will continue to be a threat. Additionally, breezy conditions will combine with low humidities once again to create critical fire weather conditions today, mainly across southern Utah, with at least a localized threat continuing into tomorrow.

As high pressure builds back into the area for the weekend into the beginning of next week, dry and very hot conditions can be expected. Temperatures are very likely to reach at least 100 degrees in most valleys over the weekend, while relative humidities in the single digits will be common. However, the pattern still looks favorable for moisture to increase into the area beginning early next week as the high pressure shifts east of the area.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Extreme Heat Watch from Saturday afternoon through Sunday evening for UTZ101>108-114>116-118>122-128>131.

Red Flag Warning until 9 PM MDT this evening for UTZ495-496-498.

WY...None.