textproduct: Salt Lake City

KEY MESSAGES

- A marginal risk of excessive rainfall will continue across much of Utah through at least Friday. This risk expands further north on Thursday and Friday.

- Temperatures will decrease 10-15 degrees by the end of the week with slightly drier air pushing into the area by the weekend.

DISCUSSION

Monsoon moisture will remain in place through Friday as the ridge responsible for this influx gradually shifts to the east. As this ridge shifts to the east a weak trough will push into the western CONUS. This will enhance lift on Thursday and Friday to expand widespread convection across all of Utah and SW Wyoming. The flash flooding risk will gradually expand into northern Utah Thursday and Friday with slot canyons, normal dry washes, urban areas, and recent burn scars will be most susceptible to flooding.

Convection will develop each afternoon and persist through the early evening before gradually diminishing overnight. The caveat with this will be for the potential for nocturnal convection. Guidance continues to hint at lingering moisture overnight, such as tonight across northern Utah, but models struggle to capture these features accurately. The most likely time for nocturnal activity will come Thursday and Friday as forcing increases. Temperatures will also trend down 10-15 degrees with the increased cloud coverage and cooling temperatures aloft.

Slightly drier air moves into the area this weekend with most of the diurnal convection confined to the higher terrain. Moisture moves back into the area next week as the ridge re-positions itself over the Four Corners. This active pattern looks to remain across the area, in some form, through the next couple of weeks.

AVIATION

KSLC...Winds will remain southerly until a transition to northwesterly expected between 19-20z. There is a 25-35% chance of showers and thunderstorms in the Salt Lake Valley between 20Z-06Z, and any shower or thunderstorm will be capable of producing gusty and erratic winds. VFR conditions will largely prevail, but can't rule out reductions in VIS from heavy rain and/or blowing dust if a thunderstorm core passes over the terminal.

REST OF UTAH AND SOUTHWEST WYOMING...Terrain-driven showers and thunderstorms will be in place this afternoon and evening, with some of this activity surviving off of the terrain and moving towards the northeast. Any shower or thunderstorm will be capable of producing briefly heavy rain and gusty/erratic winds. Latest high-resolution models insist that a complex of showers and thunderstorms will overspread northern Utah during the late evening hours before moving across northeast Utah and SW Wyoming during the late evening and early morning hours Wednesday.

FIRE WEATHER

Monsoon moisture will continue to surge into Utah through the remainder of the week with storms developing during the afternoon and weakening late evening and overnight. Some nocturnal activity will remain and persist, but the details of when and where with these storms will likely remain uncertain until the day of. Storms will be capable of producing gusty and erratic outflow winds along with frequent lightning and brief heavy rain.

A storm system approaches by Thursday that will increase southwesterly winds, but RH will remain elevated. This storm system will help to expand precipitation across most of northern Utah, persisting through Friday. Temperatures will cool 10-15 degrees across the area as this system brings a cooler airmass. By the weekend, a slightly drier airmass will limit most of the diurnal storms to the high terrain before better moisture returns next week.

SLC WATCHES/WARNINGS/ADVISORIES

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