With the monster ridge off the West Coast blocking the country from big storms we will take what we can get this week. There is storm coming inland right along the U.S./Canadian border in the Pacific NW. That storm will be associated with a large cold trough that will push South through the West over the next 2 days.
As the storm moves over land it will lose most of its moisture but the cold airmass will create orographic lift snowfall across most of the mountains. We will see 4-8 inches tomorrow in the Central panhandle of Idaho for resorts like Silver, and then Eastward into Western Montana for resorts like Great Divide. Then the snowfall will head South through the Rockies all the way down to New Mexico.
The heaviest snow will fall on the Eastern side of the mountains in Colorado to the East of the ski resorts with the upslope affect from the East. We could see 3-6 inches for places like Denver but in the resorts a few inches are possible. The biggest affects with this storm will be the cold air with high temperatures dropping into the 20’s for the mountains on Thursday.
Below is the forecast map for Thursday. Notice the cold trough outlined by the blue line. You can also see how light the precip is.
What is more interesting is to watch what happens after the cold front pushes South. Looking at the map below you can see how the cold trough really digs Southwest towards Southern California. Then a piece breaks off as the cold retracts back to the North and continues East on Friday.
The light green up in Montana is another shot of cold air and lighter snow coming down the Rockies for Saturday. Now look at the next map as the models are suggesting the Cut-off low over Southern CA moves East and merges with the now cold front near Colorado.
This looks like a shot at slightly heavier snow over CO, especially over the Southern half. We could see an additional 3-6 inches across Central CO on Saturday and 6-9 inches across the South. The next two maps show the total precipitation through this Thursday.
and then you add in Saturday…
It’s not a lot of snow, but in the pattern we are in we are lucky to see any snow. This pattern of cold shots coming down from Canada and light snowfall looks to continue into the following week, and most likely until Mid-December. As we get to mid-month and beyond there are signs in the teleconnection patterns that the storm door could re-open along the West Coast, especially in the Pacific NW. That would the path for stronger storms to make their way into the Rockies. BA