December Update

Tuesday 11/30/21 4:25 am

I was up most of the night working on a refresher explanation of the MJO. I have gotten a few emails from long-term followers about it and I have a ton of new followers so I thought it was overdue. I will be posting that discussion mid-morning. You may want to read it because I will be referring to the MJO a lot over the next few weeks. It appears we may be going into some favorable winter phases after mid-December!

Over the last couple of days, some of the ensemble models and a few operational runs have been trying to sneak in a little storm around next Tuesday, December 7th. But that is just what it is, a little warm storm.

In my last post, I was focusing on two dates, the 9th, and the 12th. I have not changed my mind. I still think it will be around the 12th before cooler air starts working into the picture.

Here are the latest maps from the extended ensemble runs of the Euro and GFS.

Euro liquid-equivalent forecast through December 11th.

GFS liquid-equivalent forecast through December 11th.

Pretty similar…

Euro liquid forecast through December 31st

GFS liquid forecast through December 31st

For snow, the Euro extended model gives me a 32-day parameter and a 46-day parameter. The GFS extended model gives me a 35-day parameter. It is also important to keep in mind that the models are locked into a 10 to 1 snow to liquid ratio. Towards the end of December, we should be between a 12 to 20-1 snow to liquid ratio.

The other thing to keep in mind is that many of the extended models have a warm forecast bias and they usually verify cooler for the period they are forecasting for.

Euro snow through December 30th

Euro snow through January 13th

GFS snow through January 2nd

My next update will be out Thursday morning. Thanks for following and supporting the site!

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