textproduct: Salt Lake City

KEY MESSAGES, Issued 1018 PM MDT Mon Jul 20 2026

- Daily scattered showers and thunderstorms will persist across the region as a monsoonal pattern remains. Monday through Wednesday night will also see a pattern favorable for continuation of nocturnal showers and thunderstorms.

- Flash flooding will continue to remain an ongoing threat across much of the region. A Marginal Risk (category 1/4) highlights more or less all of the forecast area through Friday, with a Slight Risk (category 2/4) also highlighting much of the area Tuesday and Wednesday.

- Isolated strong wind gusts 35-55 mph and small hail will be possible in stronger storms, in addition to lightning and heavy rain.

DISCUSSION, Issued 1018 PM MDT Mon Jul 20 2026

Synoptic pattern this evening remains quite similar to that of previous days. A broad ridge remains extended from the South/Central Plains on into the Four Corners region. Around the south to western periphery of this ridge a very favorable moisture tap remains, with widespread PWAT values in excess of 1", around 150% to 200% of climatological normal. While Monday has seen generally less coverage of associated showers and thunderstorms, what has formed has been aided by a slightly enhanced moist southeast to easterly inflow, helping keep activity seemingly near stationary despite more flow.

For tonight into Tuesday, a subtle embedded shortwave will shift northwestward into the area through NW NM/SW CO. While daytime heating has ceased, the mild and moisture rich environment will continue to support modest instability on the order of 100-200 J/kg or so. With the extra synoptic support from this shortwave, models continue to show some support for continued or renewed nocturnal convection shifting westward through the state from midnight through sunrise Tuesday. While activity is likely to be a bit less organized/weaker with the more limited instability, evening CAM guidance does suggest rainfall rates up to around 0.5" to 0.75" per hour in what stronger cores do develop. As such, will need continue monitor rain sensitive basins overnight. Given the overnight timing, those in such areas should be sure to have a way to receive weather alerts if stronger storms do develop/hold together.

Tuesday will see this shortwave shift into Utah, and moisture will continue to further increase with PWATs rising around the 200% to 250% of normal range. In general, this combination with very ample moisture and increased synoptic support/flow should support widespread scattered shower and thunderstorm development. Models suggest as much, and depict potential for activity capable of rainfall rates in the 1" to 1.5" per hour rate, if not possibly more in the strongest activity that forms. The extra flow will tend to help activity move a bit more than previous days, with the caveat that areas of continued moist inflow will have potential to result in backbuilding over the same area. As such, the flood potential will once again be elevated Tuesday, especially for rain sensitive areas such as burn scars, slot canyons, typically dry washes, and slickrock areas. The WPC Excessive Rainfall Outlook highlights the entire forecast region in a Marginal Risk (category 1/4), and the vast majority of Utah (generally south of the I-80 corridor) in a Slight Risk (category 2/4) of excessive rainfall. With that, southern and central Utah will have a Flood Watch in effect Tuesday for the potential for flash flooding. All that said, will need to keep an eye on the overnight to early afternoon evolution. If the nocturnal activity results in widespread lingering cloud cover or stratiform precipitation, it could help suppress activity Tuesday. Additionally, the abundance of moisture could result in activity developing quick enough and widespread enough to limit more of the individual storm potential, cloud things over, and limit the threat. Again though, otherwise the ingredients are in place for another day with a flash flooding threat. Aside from the flash flood threat, the slight enhancement to shear (around 20-30 kts) with the shortwave will give some potential for a few stronger, longer-lived more organized storms capable of gusty outflow winds up to around 55 mph or so as well as small hail.

Tuesday night into early Wednesday will once again see nocturnal showers and thunderstorms lingering, before giving way to a day that will likely see a similar evolution to that of Tuesday. Like Tuesday, there will also be some question of the exact evolution just given the amount of moisture and likelihood of preceding nocturnal activity. Provided this doesn't help limit activity, ultimately expect a day that will once again see widespread scattered showers and thunderstorms capable of efficient rainfall production, posing a flash flood threat particularly to rain sensitive basins. One interesting signal that is noted is that on Wednesday the ECMWF Extreme Forecast Index highlights much of northern Utah to southwest Wyoming particularly to indicate climatologically anomalous precipitation potential, something not noted on Tuesday. Like Tuesday, Wednesday will also see some potential for a few stronger storms capable of strong gusty winds and small hail, in addition to heavy rainfall and frequent lightning.

Thursday onward will see a bit of uncertainty in the day to day evolution, but in general the placement of the ridge will remain favorable for periods of monsoonal moisture influx into the region. Ensemble mean PWAT anomalies fall back generally into the 100% to 150% range, though individual members show potential for periods of both drier and moister than that. Additionally, there seems to be some split in the general ensemble suite, with ECMWF members more bullish on a continuation of a more favorable moisture tap, and GEFS members more on the drier side, though not necessarily in a way that would fully shut down potential for showers and thunderstorms across the entire region. For now, will just need to keep an eye on the day to day trends, as small shifts in the ridge and any potential gulf moisture rich inverted troughs will result in notable shifts in where the highest precipitation potential will be locally. Those near rain sensitive basins or planning travel/recreation will certainly want to continue to monitor the forecast for potential impacts.

AVIATION

KSLC...Southeasterly winds prevail through the remainder of the night. Nocturnal shower activity will result in periods of variable winds at the terminal between roughly 06-11z tonight, with gusts exceeding 25 kts possible through this period. Winds increase out of the northwest after 18z, before convective activity developing after 20z brings more gusty and erratic winds through the remainder of the afternoon and evening. VFR conditions prevail at the terminal, though heavier rainfall tomorrow afternoona and evening could result in brief MVFR conditions.

REST OF UTAH AND SOUTHWEST WYOMING...There is a threat for nocturnal showers and thunderstorms overnight across most of the airspace, mainly between the 06-12z timeframe; this activity will be capable of producing variable gusty winds to 30 kts for most regional terminals overnight. Otherwise, widely scattered showers and thunderstorms redevelop after around 19z on Tuesday, with MVFR conditions possible for many terminals through the evening as heavy rainfall may bring lowered CIGS/VIS at times.

FIRE WEATHER, Issued 1018 PM MDT Mon Jul 20 2026

Monsoonal moisture remains across UT increasing humidities while raising chances for showers and thunderstorms across the state moderating fire weather conditions overall. Chances for showers and thunderstorms continue to be elevated across central and southern UT this afternoon, and the Uintas ranging from 50-80%. A wetting rain remains favored this afternoon across each mentioned location. Expect showers and thunderstorms to develop along higher terrain parallel to I-15 each afternoon over the next several days around 1200-1400 with gusty outflow winds, heavy rainfall, and lightning. Winds will generally remain light terrain driven / diurnal over the next several days. Chances for showers and thunderstorms increase across northern UT starting Tuesday with notably higher chances across the entirety of UT Tuesday and Wednesday afternoons.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Heat Advisory until midnight MDT tonight for UTZ101>105.

Flood Watch from Tuesday afternoon through late Tuesday night for UTZ113-115>131.

WY...None.