textproduct: Salt Lake City

KEY MESSAGES

- An influx of near-surface smoke originating from numerous fires across the Pacific Northwest will continue through at least Tuesday.

- Dangerous heat continues across southern and eastern Utah today. Slight cooling is expected through midweek before a warming trend brings potential for widespread dangerous heat Friday into the weekend.

- Gusty winds and low relative humidity will result in critical fire weather conditions developing across the San Rafael Swell and western Uinta Basin each afternoon and evening through Tuesday.

DISCUSSION

Across central and northern Utah and southwest Wyoming, temperatures are trending about 10 to 15 degrees cooler compared to yesterday, thanks to a dry cold front that passed through the area. Post-frontal northwest flow across the region today has resulted in an influx of both vertically integrated and near- surface smoke originating from numerous fires across the Pacific Northwest, leading to deteriorated visibility and air quality across much of the area. High-resolution guidance indicates this smoke will continue to advect into northern Utah and southwest Wyoming through at least Tuesday, with central Utah continuing to see impacts from the Widemouth 2 Fire as fire activity continues.

Across far southern and eastern Utah, the dry cold front resulted in very little change to temperatures, with the main impact being increased west to northwest winds that have combined with very low relative humidity to create critical fire weather conditions across these areas. Winds taper across far southern Utah on Tuesday, but are expected to remain elevated across eastern Utah including the San Rafael Swell and western Uinta Basin, keeping an elevated threat for critical fire weather conditions in place.

High pressure redevelops across the western US around mid-week, with a ridge amplifying across the Great Basin Friday into Saturday. This pattern will favor redevelopment of widespread dangerous heat for the latter portion of the week, with continued dry conditions outside of some isolated convection along the high terrain of southern Utah. Widespread Major to locally Extreme HeatRisk is expected to develop Friday and Saturday as temperatures peak across the region. Warm overnight lows will also offer little relief, which yields heightened concerns for heat- related illness.

The area of high pressure becomes centered over the Four Corners late in the weekend, resulting in a modest monsoonal surge into the region into early next week. As such, the threat for heavy rainfall will increase as early as Sunday as moisture deepens, mainly across portions of central and southern Utah.

AVIATION

KSLC...Mostly VFR conditions with periods of MVFR conditions due to wildfire smoke will persist for the KSLC terminal through the period. Dry conditions will continue with no clouds. Wildfire smoke with remain noticeable with periods of reduce VIS 3-5SM, particularly in the morning and evening hours as slantwise VIS becomes more reduced. Winds will remain out of the northwest with a small window of southerlies possible (~30% chance) between 11Z-15Z.

REST OF UTAH AND SOUTHWEST WYOMING...A mix of VFR/MVFR conditions will continue across most of the airspace as wildfire smoke limits VIS between 3-5SM. This will be most noticeable during the morning and evening as slantwise VIS is reduced. Dry conditions will continue with no clouds. Winds across the southern airspace will remain southwesterly while northerly winds will remain across the northern 2/3rds of the airspace thanks to a weak cold front that has moved through.

FIRE WEATHER

Enhanced west to northwesterly flow prevails behind a dry cold front today into Tuesday across portions of southern and eastern Utah. Periods of critical fire weather conditions are expected to develop through Tuesday across the area as these increased winds combine with continued hot and dry conditions. Otherwise, cooler conditions with slightly improved mid-to-high elevation humidity exists across northern Utah today behind the frontal passage. High pressure redevelops across the region by midweek and amplifies across the state through the weekend, resulting in a gradual warming trend and continued critically dry conditions through the remainder of the week.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Red Flag Warning until 9 PM MDT Tuesday for UTZ482-489.

Heat Advisory until 9 PM MDT this evening for UTZ114-120-121.

Extreme Heat Warning until 9 PM MDT this evening for UTZ123-124- 128>131.

Red Flag Warning until 10 PM MDT this evening for UTZ481-483-484- 498.

WY...Red Flag Warning until 9 PM MDT this evening for WYZ277.