textproduct: Salt Lake City

UPDATE

Showers and thunderstorms, some strong to severe, persisted across northern Utah through sunset. These storms have been waning in intensity over the past hour or so, and will continue to slowly decrease in coverage and intensity into the overnight hours. The most concentrated area of convection will continue to lift through the northeastern CWA through midnight with frequent lightning and periods of heavy rain. Moisture will remain in place Monday resulting in another round of afternoon and evening showers and thunderstorms.

KEY MESSAGES, Issued 1151 AM MDT Sun Aug 23 2026

- 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

KSLC...Showers and isolated thunderstorms will persist into the overnight hours in the vicinity of KSLC, however the chance for lightning at the terminal will diminish below 10% after 06Z. Brief MVFR VIS can be expected should a heavier shower or thunderstorm move over the terminal. Winds will continue to be outflow driven through at least 06Z, varying in direction and speed, but will eventually become southeasterly/drainage by 09Z. Another round of showers and thunderstorms is expected around the general area Monday.

REST OF UTAH AND SOUTHWEST WYOMING...Showers and thunderstorms will continue across northern Utah and southwest Wyoming into the overnight hours, gradually decreasing in coverage and intensity with time. Frequent lightning, gusty outflow winds to 30 kts, and periods of MVFR VIS within heavier rain will all be possible. VFR conditions will prevail across southern Utah. Another round of showers and thunderstorms will develop across the area Monday afternoon and evening potentially impacting all terminals.

FIRE WEATHER, Issued 1225 PM MDT Sun Aug 23 2026

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.