Wasatch Window Weather: All Quiet Along the Western Front

A bright, cold, and hazy morning in the SLV. Temperatures bottomed out in the teens to 20s for the Wasatch Front valleys, with temps in the upper 20s to around 30F for the upper mountain elevations. Cache Valley caught a bit of fog overnight and early morning, while generally clear skies dominate across the remainder of the state. Colder valley temps, haze, and fog are all symptoms of high pressure and inversion conditions. The sounding from KSLC this morning definitely shows a strong temperature inversion from the surface (26 F) to about 700 mb ~ ridgetop level (34 F).

GOES-19 East True Color Imagery 1/12/2026

KSLC 12Z 1/12/2026 sounding. Inverted profile sfc-700mb

After the first true powder weekend of the winter, the excitement is starting to stabilize and the realization that we will be stuck in a holding pattern for the foreseeable future is setting in. Utah now sits on the eastern periphery of an upper-level ridge centered across the U.S. west coast. A closed/cutoff low currently resides south of the ridge over northern Mexico, revealing the beginning stages of a Rex Block pattern.

A Rex Block is characterized by an area high pressure located directly north of a closed low. This configuration slows the eastward movement of air masses and stagnates conditions across a wide area, which is why weather across the state of Utah will not change much for the next 7-10 days. Unfortunately, this means high and dry conditions with valley inversions/haze, fog, and warmer mountain temps. There may be some periods where mid-level flow and temperatures cool just enough to help vent out the valleys at times and reduce poor air quality/haze, but that is completely dependent on the degree troughs/energy graze the state.

Analyzed 500 mb heights, winds, and temps 18Z 1/12/2026

Rex Block pattern (credit: theweatherprediction)

So when will this blocking pattern dissipate and things become active again?

The ECMWF extended ensemble notes a breakdown in the ridge over the western U.S. come sometime 1/20-1/27/2026 - note the warm colors (500 mb height anomalies) in the animation below dissipating. How much the ridge breaks down and what that means weather-wise for Utah is still uncertain. But long-range models do hint that some degree of activity will return in this timeframe. TBD... In the meantime, Utah mountain and valley areas will be living through weather groundhog day.