The clouds over the mountains this morning are putting on an eye catching show. They are also alluding to shifting conditions. A low lying blanket of clouds extending from the base of Little Cottonwood up canyon and the sprinkling of lenticular clouds across the Wasatch are signs of a change in winds and moisture availability in the atmosphere.
The clouds this morning can be attributed to southwesterly flow aloft and increasing moisture ahead of a longwave trough and cold front diving south out of the PNW. The trough will begin to push into Utah through Wednesday, bringing winter weather impacts across the state going into Thursday and early Friday. This will be a more traditional or familiar type of winter storm for Utah, with more characteristic northwesterly flow and colder air than previous systems this winter.
Clouds will increase through the morning across the northern half of the state before scattered valley rain/snow and mountain snow showers begin to fill in across the Wasatch Front through the afternoon. Precipitation will initially be focused over the higher terrain through Wednesday evening as upper-level forcing and energy will be weaker. 700 mb temperatures will range from about -4 early to -6 C late Wednesday, bringing snow levels down near 5500-6000'.
By late Wednesday night into Thursday morning, the main trough energy and cold frontal boundary will progress over the region, aiding in stronger lift/ascent and a period of greater precipitation coverage and rates. During this timeframe, winds will also shift northwesterly, allowing a switch over to a cold air advection regime and greater orographic induced snow. The cooler temperatures will transition rain/snow showers in the valleys over to all snow by early Thursday morning.
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| ECMWF 00Z 1/7/2026 four-panel forecast 1/7-1/9/2026: (Top left to bottom right) MSLP/precip and 1000-500 mb thickness; 300 mb gph and winds; ; 500 mb gph, vorticity, and winds; 700 mb gph, RH, temp, and winds |
The heaviest snowfall rates in the valley and mountains are expected to occur sometime between the predawn hours to mid morning Thursday. Northwesterly flow will keep upslope showers going into the Cottonwoods through most of Thursday and potentially even into Friday morning. However, the duration of terrain induced snowfall will rely on how long winds remain northwesterly and therefore total mountain snow accumulations will also depend on this. Showers decrease and become more intermittent to scattered in the valley into the afternoon hours, but there is the potential for a lake effect band to setup during this time.
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| ECMWF ENS 00Z 1/7/2026 10:1 Snowfall Total (in) at KSLC |
Model ensemble average (green line above) puts 3-5" of snow in the SLV by Thursday afternoon, but accumulations across the valley will likely be area specific, with localized amounts potentially being higher or lower. Deterministic models differ in placement of higher end totals for snow, with the ECMWF favoring larger totals for the northern and western half of the SLV and the GFS favoring larger totals for the east side and east benches.
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| Left: ECMWF 00Z 24hr precip total (in); Right: GFS 12Z 24hr precip total (in) |
Valley snowfall amounts will be heavily dependent on both the timing of the change over from rain/snow to snow and how long winds remain northwesterly versus northerly. Additionally, the formation of lake enhanced snow showers or a lake effect snow band is possible, but there is uncertainty in timing and location of such a feature. Currently, models setup a lake effect band oriented across the western half of the SLV over the Oquirrhs to Tooele Valley mid morning Thursday through the afternoon. Total valley snow accumulations will obviously be heavily impacted by any lake effect snow. If a lake band does develop, impacted locations could see higher totals in the 6-10" range.
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| UoU GFS Ensemble 00Z 1/7/2026 Total Snow for Alta, UT 1/7-1/13/2026. (credit: UoU Atmo Sciences) |
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