textproduct: Salt Lake City

KEY MESSAGES, Issued 106 PM MDT Thu Sep 17 2026

- Showers and thunderstorms are expected to develop this afternoon and evening across northern and central Utah. After a brief lull overnight, activity ramps back up late Friday morning.

- Flash flooding remains the main concern across central Utah through Friday, while severe winds and large hail remains the main threat across northern Utah.

- A cold front brings drier conditions with more seasonable temperatures Saturday through the remainder of the weekend.

DISCUSSION, Issued 106 PM MDT Thu Sep 17 2026

With deep moisture and modest instability in place across northern and central Utah this afternoon, convection is expected to redevelop through this evening. Across northern Utah, coverage is expected to be more isolated given the convective activity that already moved through this morning. However, recent mesoanalysis indicates that greatest instability and shear will be focused across the northern Wasatch Front this afternoon and evening with 500-1000 J/kg of MLCAPE and about 30-40 kts of effective shear. As such, any storms that can develop through this evening will be capable of sustaining updrafts that would be capable of producing an isolated wind gust in excess of 58 mph and hail greater than 1 inch. Across east-central Utah, more modest instability will exist with much deeper moisture (PWATs 1.0-1.2") in place. As such, storms in this area will be capable of producing heavy rainfall, with rainfall rates of 0.5-1+" per hour possible. Given recent rainfall across portions of central Utah, especially the San Rafael Swell and Wasatch Plateau, conditions are favorable for flash flooding across these areas.

Convective activity will wane late this evening and overnight, but lingering instability associated with a closed low pressure system moving eastward across the Great Basin may allow showers and thunderstorms reinvigorate across northern Utah early Friday morning. A vorticity lobe ejects through the northern half of the state late Friday morning, maximizing instability across the region and resulting in increasing coverage of convection across northern and central Utah and southwest Wyoming through the afternoon. Conditions will once again be favorable for severe wind and hail across northern Utah.

Convection clears out late Friday night, with drier conditions prevailing through Saturday behind the closed low. Much cooler conditions are expected to give us another taste of fall on Saturday, with highs around 10 degrees below average. This cooler and drier trend won't stick around long as another low pressure system digs down the coast of southern California on Monday, yielding moist, southerly flow across the region which will bring increased chances for showers and thunderstorms mainly across southwest Utah early next week.

AVIATION

KSLC...The SLC terminal will see VFR conditions through the evening with southerly winds. Periodic showers are expected to develop tomorrow morning, most likely between 10Z and 12Z, bringing the potential for periods of gusty and erratic winds through the morning. By the late afternoon, additional scattered showers and thunderstorms are expected to develop, with a 30 percent chance of producing gusty winds through the early evening tomorrow.

REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected across the airspace through the evening. Scattered showers will continue into the early evening, primarily focused over northeastern portions of the airspace. These will bring a low chance of lightning, gusty winds, and brief mountain obscurations. During the early morning, most likely beginning between 10Z and 12Z, another round of showers is expected to develop, focused over northern portions of the airspace, lasting through much of the morning. Additional showers and thunderstorms are then expected to develop by late afternoon, again for northern portions of the airspace.

FIRE WEATHER, Issued 106 PM MDT Thu Sep 17 2026

Isolated to scattered showers and thunderstorms are expected to develop across portions of central and northern Utah this afternoon and evening. Deep moisture in place across eastern portions of the state will favor a threat for heavy rainfall and flash flooding, across east-central Utah, mainly across the San Rafael Swell and Wasatch Plateau. Otherwise, storms will be capable of producing lightning, large hail, and gusty outflow winds. Similar conditions are expected on Friday afternoon and evening, though drier air moving into the region will moderate the heavy rainfall risk slightly. A cold front works its way through northern Utah on Saturday, resulting in much cooler and drier conditions through the remainder of the weekend. Southerly flow developing on Monday ahead of a low pressure system deepening along the southern California coast will introduce increasing mid-level moisture across southwest Utah through mid-next week, with improvements in both daytime RH and overnight recoveries through this period.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Flood Watch until midnight MDT tonight for UTZ113-117-120-121.

WY...None.