textproduct: Salt Lake City

KEY MESSAGES

- A general 6 to 12 inches of snow can be expected through early Sunday morning across the higher terrain of Utah, with local amounts up to 2 feet for the upper Cottonwoods and Bear River Range.

- There is a 60 to 80 percent chance of measurable snow for much of the Wasatch Front Saturday night into early Sunday, although most valley floors will see less than 1 inch.

- Temperatures will drop to or below seasonal normals this weekend, staying near normal through early next week as drier conditions move in.

DISCUSSION

Utah remains under a southwesterly flow aloft this afternoon while a mean trough with several embedded shortwave features remains upstream but is approaching the area. An H7 baroclinic zone associated with a shortwave feature currently ejecting into western Montana is pushing into northern Utah. A band of precipitation is noted on radar imagery near this boundary. Meanwhile, a moisture plume with modest IVT anomalies continues to spread into Utah from the southwest, aiding a few showers ahead of the boundary. Surface winds remain gusty out of the south areawide, but have not been as strong as previous days and will continue to trend downward into the evening hours. The Wind Advisories are no longer in effect.

Precipitation will continue to spread into central and southwest Utah tonight as the boundary advances southward. Snow levels will gradually lower during this time with the arrival of increasingly cooler air, but with H7 temperatures only reaching around -8C across far northern Utah by 12z, snow levels are expected to remain above most valley floors through the night. By tomorrow morning, focus for precipitation will shift more towards southwest Utah along with mountains favored in a northwesterly flow. Afternoon max temperatures will fall into the 40s for most valleys tomorrow, which will still be around 5-10 degrees above normal for this time of year.

Tomorrow afternoon, the shortwave trough currently noted over the southern BritCol coast will approach northern Utah. This will push a reinforcing cold front into the area. This will cause a relatively brief uptick in precipitation as the boundary moves through. Much colder air spreading in behind this boundary will bring the best chance for valley snow, and SLC may finally see its first day of measurable snow this season. Valley accumulations are not expected to be very significant, however, as drier air will quickly spread in behind the boundary. Most valley floors along the Wasatch Front and the Cache Valley have less than a 20 percent chance of seeing more than 1 inch of accumulation per the NBM, with around a 40-50% chance on the benches. The exception is the Salt Lake Valley, which has a 20-50% chance on the valley floors and 50-75% chance on the benches. Additionally, some lake enhancement or lake-effect showers may boost amounts locally, mainly across the western and southern portions of the Salt Lake Valley. The airmass will be plenty cold enough to get the lake going, but the main limiting factor is the aforementioned drier air in the postfrontal environment. Precipitation will largely wane by midmorning on Sunday across most areas. However, with continuing cold advection with H7 winds of 35-40kt and a northerly surface pressure gradient, expect some gusty canyon winds in Washington County Sunday morning.

Thereafter, high pressure will build into the area through midweek. This will maintain dry and stable conditions with strengthening inversions as temperatures gradually warm aloft, trapping the colder air in the valleys given weak flow through this timeframe. Afternoon maxes are likely to hover near to slightly above climo, although there is some question as to how well the NBM is handling inversion temperatures, especially towards midweek, given the lack of recent events. Model consensus has the ridge breaking down late week, but there is enough spread to make it difficult to nail down any specifics at this time on the timing and strength of the next trough.

REST OF UTAH AND SOUTHWEST WYOMING

A cold front will cross northern Utah this evening turning winds to northwesterly. Showers will fill in behind this front, with snow levels falling to near 5000 feet within heavier showers. There is a 20% chance of thunderstorms along and behind the front this evening. To the south of the front gusty south winds and areas of MVFR visibility with blowing dust will persist into the evening hours before diminishing overnight.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Winter Weather Advisory until 5 AM MST Sunday for UTZ110>113.

Winter Weather Advisory until 5 PM MST Saturday for UTZ117-125.

WY...None.