A warm southwest flow will remain over Utah on Monday, bringing high elevation snow and low elevation rain to the Wasatch region. However, changes will arrive on Tuesday as the next organized low pressure system moves across Utah, spreading much colder air into the state with rain changing to snow in Salt Lake City.
Several inches of accumulation will be possible across the Salt Lake City area from Tuesday afternoon through Wednesday, while flash freezing of previously wet roads will be of concern Tuesday evening.
The image below shows this morning’s upper level pattern – we can see a trough of low pressure center just off the Pacific Northwest Coast in Washington (image source: College of DuPage).
This low pressure system is moving from north to south down the West Coast and transporting cold air southward along with it. This pattern is actually producing snow across the Seattle area this morning.
This low pressure system and colder air will eventually swing eastward into the Great Basin and into Utah on Tuesday. Temperatures will remain warm enough overnight tonight for precipitation to remain as mostly rain across the Salt Lake City area, before a cold front arrives Tuesday morning with high temperatures peaking early in the day.
By Tuesday afternoon, we can see the low pressure system is located over the Great Basin and moving into Utah (image source: Colorado Avalanche Information Center).
Look for a rain/snow mix Tuesday morning for Salt Lake City, before transitioning to all-snow by around noon or shortly after. Good melting is expected initially with snow that falls Tuesday afternoon, but by late afternoon or early evening, snow will begin to accumulate on all surfaces as temperatures fall below freezing.
In addition, roadways will likely become icy Tuesday evening and overnight as previously wet roadways freeze up. Temperatures overnight will fall into the low/mid 20s across the Salt Lake City area.
Snow will continue to fall at times (mostly at light to moderate rates) overnight Tuesday and continue well into the day Wednesday, before tapering off Wednesday evening. Temperatures will likely remain in the 20s for Salt Lake City during the day Wednesday with snow accumulating on roadways. The Wednesday morning commute will be impacted the most, especially with icy conditions expected under new snowfall from previously wet roads freezing over.
Models are somewhat variable on snowfall amounts with the NAM model coming on a little bit lower, but this seems to be an outlier while the European and American GFS Models are coming in a little higher. While this is a low resolution model, the GFS image pictured below (image source: pivotalweather.com) is generally in line with our thinking.
Overall, we expect snowfall totals will most likely end up in the 3-6″ range for Salt Lake City down to Provo, with higher amounts for the benches near the Wasatch Foothills, and lower amounts farther north from Ogden to Brigham City (although Logan is probably closer to what SLC receives).
Following this storm, a chilly airmass well settle into the region on Thursday and Friday before the next system approaches this weekend.