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 50 to 70 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

The first of two storm systems to impact Utah and southwest Wyoming this weekend is currently over the area, with the best moisture and instability along a band from northeast to southwest Utah. Associated precipitation (mountain snow, rain below 5,000 feet or so) has been steady but generally light. Currently seeing peak coverage over northern Utah before it becomes more showery this afternoon. Given totals so far, expect totals to verify more on the low side of the going forecast. Shortwave energy from the trough will keep precipitation going over southwest Utah, through much of the afternoon. Temperatures will be more typical of late December today, near climo across southern Utah and averaging 5F above across northern portions of the area.

The second and much colder system is on track to graze northern Utah tonight into early Sunday. Primarily impact will be the associated temperatures, with guidance indicating 700 mb temperatures as low as -16C Sunday morning, dropping snow levels to valley floors. The limiting factor for snow with this system will be the lack of moisture, given the colder origin of the system, and relatively quick drying behind it. Thus, it is likely (50-70 percent chance) that will snow down to northern Utah valley floors, but associated accumulations will be primarily light at best. The one question mark would be the potential for lake enhancement, as the temperature difference will be there, but again, the lack of moisture will be the limiting factor.

Behind the second system, high pressure centered off the Pacific coast will build into the Great Basin for the early part of the week. This will result in dry conditions with steady warming aloft. However, the dreaded valley inversions will likely limit warming for the lower elevation areas, keeping temperatures relatively close to seasonal normals. Some guidance indicates more unsettled weather returning toward the end of the forecast period, but overall spread remains quite high at this time.

REST OF UTAH AND SOUTHWEST WYOMING

A mix of VFR, MVFR, and IFR conditions will continue across the entire airspace. Valley rain and mountain snow across the airspace will shift south through the day with reduced VIS and CIGs leading to mountain obscuration. The heaviest precipitation will be across the central airspace. A cold front will bring isolated snow showers to the northern airspace during the afternoon with northerly winds behind it as it shifts south during the evening. Otherwise, winds will be light and diurnally driven with variable wind gusts associated with nearby showers.

SLC WATCHES/WARNINGS/ADVISORIES

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

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

WY...None.