Storms Before During And After Thanksgiving

Late Monday a fast-moving cold storm will move across the region and at the moment looks like it is going to hammer the Denver area and the Front Range with 6-10 inches of snow ending Tuesday afternoon. A piece of that system will also move across our area, at the moment it looks like 0-4 inches for us (lower and mid-elevations and Purgatory). Telluride could see 5-10 inches. The models seem to have their minds up that this system will come in with NW flow which favors Telluride and not Purgatory or Durango. Could that change? Of course, what would need to happen is the system would have to drop deeper into the west. Below shows what the conditions are supposed to look like according to the GFS on Monday at 5 pm. I circled in green the trough position and drew a line to the west of where that trough would have to come in in order for Purgatory and Durango areas to get more snow. We would then have westerly flow as it moved across and possibly SW flow as the low lifts out.


This is an unlikely scenario, but it is certainly possible. I remember it happened in early December 2008, but I haven’t seen the models miss that bad since.

As far as snow totals, the GFS has always been more bullish on this first storm, the Euro and Canadian took a while to even acknowledge it, they show roughly half of the GFS is expecting, but the GFS is trending down.

By Tuesday evening here is what the GFS shows.


Here is the Euro


And the Canadian


The upside is the storm is much colder than the last one, the snow ratios will be high, these maps show 10-1 ratio of snow to liquid, in other words, 1 inch of liquid equals 10 inches of snow. I expect the ratios to be at least 15-1 in SW Colorado for this first storm which will make the most of the light precipitation.

For travelers, Monday looks good until about sunset, travel will be difficult from 8 pm on Monday to 5 am on Tuesday. On Tuesday light snow will fall throughout the day across the state, in our area, it will be less common. Always keep in mind when I write these narratives I am interpreting the model data, the most recent model runs, prior runs and how the models are trending. This is why it is important to read the most recent post to get the most recent information if something changes I try to make a big enough deal about it, that everyone will know.

On Tuesday night as the first storm leaves, the second storm slams into California as you can see below.


By Wednesday morning snow should break out in the mountains and by noon it could start getting heavier. Below you can see the areas in blue are snow, the darker the blue the heavier the rate of snowfall.


Also in this map, you can see the moisture streaming up from Mexico (in green). I am not sure if the models have figured out what to do with this, at one point they pushed that precip into our forecast area which had a huge effect on snow levels with a lot of rain in the lower elevations. The Euro is off that trend, for now, we will see. In this case, it could still affect New Mexico travelers.

By Wednesday late night, the Euro thinks it will look like this


In this run, it shows the snow level in New Mexico around ABQ and Santa Fe around 7,000 feet. Heavy snow in Flagstaff and most of Utah. Here is a zoomed-in for Colorado.


By Thursday 8 am regional view


Colorado view same time


That would be great!

Now Thursday at 5 pm, things are tapering off, except for Wolf Creek.


But wait I mentioned storms after Thanksgiving. After this lull, another piece starts to come through.

Friday 5 am Regional view

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Colorado view


Friday 5pm


By Saturday 5 am


All said and done here are the second storm totals, first the Euro


And the GFS


I am not going to post the Canadian but I will tell you it is double the Euro.

So, obviously, things are likely to change between now and then. Previous model runs have been higher and lower. I will update again tomorrow but I won’t go into as much detail again until Tuesday, I will talk about any differences I am seeing and how the models are trending. This could be the snowiest Thanksgiving I can remember since I moved here 11 years ago. So all of you long-time followers know the drill, get your cars washed on Tuesday and put up your snow (Christmas) lights on Wednesday, that usually does the trick!

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