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 1139 AM MDT Thu Jul 9 2026

KSLC...Showers and thunderstorms will begin to develop over the Oquirrh Mountains after ~20-21z, but will likely stay south of the terminal through the afternoon. However, there is still a ~20% chance that a shower or thunderstorms does drift over the airfield before 02z. Gusty outflow winds are more likely to produce an impact, potentially resulting in a wind shift to gusty southerly/southwesterly winds as early as 23z (10% chance of exceeding 40kts briefly). Winds will become lighter and terrain- driven after 02z, becoming light and variable at times overnight.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and thunderstorms will develop after 19-20z across portions of Utah north of I-70 and primarily along/south of KENV-KSLC-KEVW. These storms will be capable of producing gusty and erratic outflow winds generally 20-30kts, though stronger storms could result in gusts exceeding 45kts (10% chance). Winds could kick up some BLDU, resulting in temporary VIS reductions. Showers will likely diminish by 02z. Across southern Utah, breezy southwesterly winds are expected this afternoon with mostly clear skies.

FIRE WEATHER

Isolated showers and thunderstorms capable of producing gusty and erratic outflow winds to 40-50 mph are expected this afternoon, mainly across the high terrain of central and northern Utah. An increasingly dry airmass continues to build through this weekend, limiting convective development and resulting in very poor to virtually nonexistent overnight humidity recoveries across most of the state. Given already critically dry conditions in place, elevated afternoon southwesterly breezes across southern Utah will result in periods of critical fire weather conditions today and Friday. Winds are expected to become light this weekend as a strong ridge of high pressure develops across the Intermountain West. Temperatures will climb to near or above record values for many locations through the weekend. As the ridge shifts eastward slightly early next week, an influx of mid- level moisture will bring increasing cloud cover that will moderate temperatures slightly and result in a gradual increase in RH across the region.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Extreme Heat Warning from noon Saturday to 6 AM MDT Tuesday for UTZ101>108-114-116-118>121.

Extreme Heat Warning from noon Saturday to 6 AM MDT Monday for UTZ115-122-128>131.

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

Red Flag Warning from noon Friday to midnight MDT Friday night for UTZ495-496-498.

WY...Heat Advisory from noon Sunday to 9 PM MDT Monday for WYZ021.