An unusual but very good pattern is looking to set up over the western U.S. that could bring rather continuous active weather to the Colorado mountains starting Thursday and possibly lasting through the new year. This pattern will pretty much guarantee that mountain locations will have a white Christmas or least have snow falling on Christmas Day.
An Aleutian High will be building and maintaining its strength for quite some time. A similar type of pattern was seen this summer when a blocking ridge was set up over the Western U.S., keeping Colorado warm and dry and allowing for all storms to pass by and not impact us. Well, this go around, the blocking ridge is far to our west and north and that will allow for all of the storms to travel toward our area. If the models are correct, this could be the pattern for the next one to two weeks. Or more.
This type of weather pattern is something that could be a game changer for the western water woes. A continuous stream of active weather means that nearly consistent snow (and moisture in general) is possible for the foreseeable future. On top of this, some lingering atmospheric river moisture is poised to impact Colorado maybe more than once during this period leading to even bigger storm totals.
An Atmospheric River event is looking more likely to impact Colorado by Friday.
This could bring extremely heavy snow to the Western and SW mountains of the state just before the weekend. #AR #COwx #Snow pic.twitter.com/csjm0sFIDi
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Shine I’m Andy Stein (@AndySteinWx) December 21, 2021
Colorado’s first round of significant moisture comes Thursday to Friday as moisture from the tropics will make its way through the Southwest and into Colorado. Due to the winds’ direction, the San Juans and Western Slope mountains will see the biggest impacts, but all mountains will experience some benefit from this. The southwest winds will be pumping in some mild air as well so snow levels are initially going to be rather high, above 8,000 feet at times before dropping to the valley floors.
Favorable winds continue through the weekend and although the amount of moisture will lessen for Saturday and Sunday, there will be enough support for snow showers to remain steady both days.
While this pattern does not support snow or rain for areas east of the mountains, the San Juans, Elk mountains and Park range should be the big winners through Sunday with possibly over 2 feet of snow in four days. The majority of ski areas in Colorado should get at least a half foot of snow by the end of the weekend, making for a great ski holiday but also making for some extremely tough travel. After this, the active pattern continues as the new year approaches. Snow looks to continue almost daily as January nears, leading to even more impressive snowfall totals and endless powder days.
This active pattern is great news for our current snowpack which is sitting below average statewide. Most basins in Colorado should get pumped back up to near average by the end of this storm cycle.
This is a great setup for snow in Colorado, and this should reduce stress levels of having a below-average snow season in the mountains. December and January tend to be very good months for the Colorado Rockies, and it’s good that we are going to end December on a strong note.
This content was originally published here.