?? The Greenland block is already developing right now as of this moment. This isn't a fantasy like it was last year. Not sure what the point of that tweet is.
It may seem like a wild fantasy, well, it is. For another 5 to 10 years at least. 2009-10 like years have a return period of every 20 years or so most likely. The least we can expect between now and 5 years is one like 2013-14 or 14-15.
Or it could start in January of 2021 and we wouldn't even know it. There's always that 1 percent chance that LR models dramatically flip from warm to cold and snowy within just a few model runs, under 7 days out and it verifies. OTOH we could be dealing with years before we get another decent winter. I'm going out on a few limbs to say that 2021-22 will be at least half decent. This winter will probably be another non-winter like last year.