12/20/21 Monday 4:50 am
Good morning, and welcome to the latest episode of what I know and what I don’t know...
In case you missed my post from Sunday morning, I talked about trying to sort out speculation from what I actually think I know. This has been a recurring theme and probably expands to all forecasters who are trying to get a handle on the series of storms headed our way between Thursday, and likely the first week in January.
What I thought I knew yesterday I still believe today. A storm or series of storms are going to have major winter impacts above 8,500 feet. This should get underway sometime on Thursday.
At the moment, there are still a lot of questions about the timing of the lulls in the precipitation between Thursday and next Tuesday. I believe the problem originates with the ensemble models of the Canadian, GFS, and Euro. All three ensemble families’ mean runs show precipitation starting on Thursday with at least some precipitation every single day through January 4th.
As I mentioned yesterday this is an improbable solution. What I did not mention yesterday is what I think is causing the problems with the models. I think this is all due to what I believe will be a major upcoming pattern change across much of the country. This pattern change could result in a severe cold outbreak as we approach January. I think the models are trying to figure out how to disperse the cold air.
I actually wish we would have some more cold air at the beginning of the next system but I don’t think that is going to be the case. At the moment, it appears the lower and some of the mid-elevations are going to struggle with a rain/snow mix similar to the system that hit us earlier this month on the 9th.
Because the models vary on when the lulls in precipitation are going to occur, I had to pick an end time for precipitation amounts. I chose Saturday the 25th at 11 pm. We are going to get another batch of precipitation between Saturday and the following week, I just don’t know when it is going to start, or if there will be any type of break.
With that in mind here are precipitation forecast maps between early Thursday and late Saturday.
Previous GFS 6 hours earlier, notice the discrepancy in the precipitation amounts across the lower elevations.
NWS blended model
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