Winter Is On The Way

12/3/21 Friday 9:00 am

It is difficult not to get excited about the model runs. Especially the GFS and Canadian models along with their ensemble members.

I have often written about model biases. The two biases that always jump off the screen are the Euro and GFS’s bias in failing to detect cold after about 7 days. The other biases are that the GFS moves storms too quickly from west to east, while the Euro tends to overdevelop a storm in the west and move it too slowly to the east.

That is what makes these model runs (48+ hours worth) for the GFS and Canadian so intriguing. The GFS is acting outside of its normal bias pattern. That does not mean it is right, we will have to see. What is very encouraging is the agreement among ensemble members and how it continues into the GFS long-term extended model. The same situation applies to the Canadian model.

We are still 7 days out from what could be a very big storm for the area. That is why I am trying to not get too excited and get everyone’s hopes up. The consistency in the GFS and Canadian, as well as their respective ensemble model (family) members, is nearly too good to be true.

It is certainly not unheard of, we have had big mid-December storms in the past. I think it is the anomalously dry and warm conditions that we have been experiencing lately that are giving me the “too good to be true” mentality.

Late Monday through Tuesday a storm will drop down from the north and leave a bit of snow, especially for northern portions of the forecast area. A couple of inches of snow up to half a foot could accumulate. The lower elevations will likely see a few drops of rain or light rain and snow mix.

The GFS and Canadian show a very potent storm beginning either late Thursday or early Friday. The latest runs are showing heavy snow across the area that eventually will move out of the area late Saturday. The Euro shows the storm but has been inconsistent from run to run with the storm track and the amount of snow.

Here are the liquid precipitation and snow forecasts from the various models. These totals reflect both storms. Starting on Sunday I will be able to add a couple of more models which have shorter run times to the mix. If these are correct, the snow totals above 8,000 feet could be 20 to30 percent higher than what the models show.

GFS liquid

GFS snow

Canadian liquid

Canadian snow

Euro liquid

Euro snow

Previous Euro run liquid

Previous Euro run snow

You can see the Euro is not calling for a miss, it is just not as enthusiastic as the other two models. Given our current situation, if we were only looking at the Euro we would still be excited about this storm. But given the other two model runs, I have become snow greedy.

The long term still looks great.

Here are the (positive) forecasted precipitation anomalies for the long term. These maps display how much liquid precipitation is being forecasted (above average) by the models.

GFS 35 days outlook

Canadian 32 day outlook

Euro 46 day outlook

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