textproduct: Salt Lake City

KEY MESSAGES, Issued 1151 AM MDT Sun Aug 23 2026

- A Slight Risk (level 2/5) for severe thunderstorms is outlooked this afternoon and evening across much of northern Utah. There is a 10% chance of wind gusts in excess of 70 mph with these thunderstorms.

- There is a Marginal Risk (level 1/4) for excessive rainfall across most of the region through early next week.

- Thunderstorms will continue to impact the higher terrain and adjacent valleys through Wednesday. Another round of more widespread thunderstorms is increasing in likelihood for Friday into early next weekend.

DISCUSSION, Issued 1151 AM MDT Sun Aug 23 2026

Strong to severe convection will develop this afternoon and evening, with the highest probability of significant impacts (10% chance of wind gusts in excess of 70 mph) across northern Utah. A Slight Risk (level 2/5) for severe thunderstorms has been issued for this area by the Storm Prediction Center. Looking at the set-up, this morning's 12Z sounding at KSLC already showed almost 1000 J/kg MUCAPE but with a fairly stout amount of convective inhibition. Latest guidance suggests this effective cap will erode by 20-21Z, allowing for robust convective development across northern Utah. Mean HREF SBCAPE indicates a broad area of values near to above around 1000-1500 J/kg across northern Utah coincident with deep layer shear around 25-30 kts.

Weak surface convergence associated with a shortwave trough passing to the north may help to organize convection into a quasi-linear feature, though per typical in terrain, this is difficult to discern in model fields. The latest few HRRR runs do show a signature of an organized line of very strong outflow shifting across the west desert and into the Wasatch Front between 21Z and 01Z and then continuing to be quite strong into the Uinta County, WY area by 02-03Z. Peak wind gusts in these runs have increased to 55kts, but given the very steep lapse rates, relatively high instability for the Great Basin, modest deep layer shear and low LCLs, expect storms to be able to attain cold pool/shear balance. Saturday's convective outflow peak was 80 mph near Grassey on I-80...cant rule out a repeat somewhere along this area of outflow winds this afternoon and evening.

For areas south of I-70, the heavy rain threat continues. While HREF peak 1 hour rates have decreased over Saturday's values, net available moisture has only decreased subtly. Expect any stronger thunderstorms, especially those tied to terrain features and/or training, to be capable of rainfall rates in excess of 0.50 inches per hour. Will need to monitor for flash flood threat across much of this area...especially for slot canyons, normally dry washes and recent burn scars.

With the previously mentioned upper level trough passing to the east Monday, the best chance for strong outflow winds will shift to mainly the Utah/Idaho border region. Convection will become increasingly tied to the higher terrain and adjacent valleys through Wednesday...with only isolated convection expected Thursday as high pressure brings a drying trend to most locations.

However...with the tropical eastern Pacific remaining quite active, at least a portion of ensemble members indicate the next trough approaching the Pacific Northwest will assist in shifting remnant tropical moisture into the Great Basin by Friday. This is something to watch moving forward.

AVIATION, Issued 1151 AM MDT Sun Aug 23 2026

KSLC, Issued 1151 AM MDT Sun Aug 23 2026... A few thunderstorms will begin to develop over the Salt Lake Valley after 20z or so, resulting in low confidence in wind direction with any outflow winds. After 00z, a more organized cluster of thunderstorms is looking more likely to impact the terminal, bringing a chance for lightning, MVFR VIS due to moderate- heavy rain, and gusty outflow winds. Winds could even exceed 50kts out of the west (or become variable) as this line moves through. There is still some uncertainty with the timing of this cluster. Weaker showers will linger in the area until 07z or so, with breezy easterly winds slowly becoming lighter out of the southeast.

REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and thunderstorms will continue to develop this afternoon across UT and southwest WY, with lower chances at KCDC and KSGU. Any showers will be capable of producing strong and erratic outflow winds, with the strongest winds across northern UT/southwest WY. Here, winds are more likely to briefly exceed 50kts or even 65kts near the strongest storms. A more organized cluster of thunderstorms will sweep through KTVY-KSLC-KOGD-KEVW between roughly 00-05z, which may produce very strong winds, MVFR VIS due to moderate- heavy rain, and lightning. There is still uncertainty with exact timing of this cluster.

FIRE WEATHER

High pressure will remain across the Four-Corners region through the next week. As an upper level low crosses southern Canada into the northern Intermountain Region through Monday, sufficient forcing for thunderstorms will continue. As a result, strong to severe thunderstorms will impact much of northern Utah this afternoon and evening. The most significant threat will be strong outflow winds in excess of 60 mph, mainly north of I-70. For locations south of I-70, strong outflow winds up to 50 mph and very heavy rain will be the primary impacts from thunderstorms.

Additional strong thunderstorms will develop Monday afternoon and evening, but the threat of outflows in excess of 50 mph will remain closer to the Utah/Idaho border. As high pressure builds north and east in the wake of the upper level low Tuesday, thunderstorms will become more confined to the higher terrain and adjacent valleys through Thursday. A net drying trend will continue, with most valleys see humidities fall to critical levels by midweek. Another round of thunderstorms may impact more of the state as early as Friday as another low pressure area impacts the Pacific Northwest and pulls moisture from the tropical Pacific northeastward into the Great Basin.

SLC WATCHES/WARNINGS/ADVISORIES

UT...None. WY...None.