Under southwesterly flow, temperatures are inverted this morning. A subtle short-wave trough embedded in the large-scale flow will bring slight chances for precipitation this evening.
Nowcast
Mostly overcast skies prevail in the Wasatch with some light precipitation falling near the Alpine ridge which divides Little Cottonwood Canyon and American Fork Canyon and the Wasatch Back. That can be seen on the latest KMTX radar imagery, which suggests precipitation rates around 0.5-0.6 mm/hr.
This is a quick-moving band of precipitation that should pass through the Wasatch in the next hour or so. We remain under inversion conditions. Temperatures at the Salt Lake City airport (KSLC) are 29 °F at 8:45 a.m., while temperatures at the base of Alta Ski Area are 36 °F.
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| Source: NOAA/University of Utah Department of Atmospheric Science |
This is a quick-moving band of precipitation that should pass through the Wasatch in the next hour or so. We remain under inversion conditions. Temperatures at the Salt Lake City airport (KSLC) are 29 °F at 8:45 a.m., while temperatures at the base of Alta Ski Area are 36 °F.
Short-term
A short wave trough in the large-scale southwesterly flow will cross northern Utah this evening, bringing additional chances for precipitation.
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| Source: University of Utah Department of Atmospheric Science |
That feature can be seen in the curvature of the black contours which show 500-mbar geopotential height in the upper left plot. The GFS calls for about an inch of snow with this system, so it should not do much to improve skiing and riding conditions.
Mid-long Range
A closed low pressure system is moving south along the coast of California (see left two plots above), but that will not do anything for us precipitation-wise. At the same time, a closed low will move south from Idaho late Saturday and make its presence in Northern Utah, and dropping 700-mbar (crest level) temperatures, quite quickly. This system can be seen in the 0000 UTC Sun 24 Dec 2023 GFS forecast shown below.
There will be precipitation associated with this system, although amounts remain unclear. NAEFS downscaled model guidance for Alta suggests anwhere from 0 to 2.7 inches of precipitation through the evening in Christmas day.
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| Source: University of Utah Department of Atmospheric Science |
There will be precipitation associated with this system, although amounts remain unclear. NAEFS downscaled model guidance for Alta suggests anwhere from 0 to 2.7 inches of precipitation through the evening in Christmas day.
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| Source: University of Utah Department of Atmospheric Science |
We will have to wait until models reach better agreement to nail down forecast amounts.
If you will be traveling in the backcountry, make sure you have the proper equipment and know before you go. For the forecast as well as all things avalanche, head over to our friends at the Utah Avalanche Center.
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