Benefits of a Dirty Ridge

Posted Wednesday, January 22nd, 2020 by Eric McNamee

TL;DR: Waves of moisture will be rolling in from the Pacific with a low amplitude ridge parked off the west coast. No serious accumulations but shots of moisture almost every other day over the next week.

Currently, a weak shortwave trough is exiting the region. Unstable northwesterly flow and anomalously high amounts of moisture in the atmosphere have allowed for light showers and gloomy skies to continue throughout the day. Light showers will continue heading into tonight and should taper off by tomorrow morning as that weak shortwave trough continues to move off to the east. 

Short-Term: Light showers are still possible tonight in higher elevations but should taper off by tomorrow morning. The next chance for some snow will come during the day Friday from a weak shortwave trough moving through the flattened ridge. The dynamics with this shortwave trough are very weak but with the anomalously high moisture surge and the little bit of lift associated with the shortwave will allow for showers to develop along the Wasatch. Accumulations will be similar to what we’ve seen today so I would expect accumulations in the 3-6” range likely.

GFS 6 hour precipitation accumulation Friday through noon Saturday (

Long-Term: Conditions will be relatively dry through the remainder of the weekend before another shortwave trough looks to dig into the western US during the day Monday. Right now, most models are indicating this trough to split over the western US but vary in the amount of precipitation. Regardless, another round of snow in the mountains is looking likely. We will have a better idea of how much will accumulate when we get closer to Monday.

NAEFS ensemble plumes for Atla, UT (

Another chance of snow around Wednesday/Thursday of next week, but snow amounts are still uncertain.

Overall, showers will continue on-and-off for at least the next seven days, with minor accumulations expected right now. Make sure to stay tuned over the next week with waves of moisture moving in!


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