Active Thanksgiving Week

Today was a perfect fall day:

Beyond the Vet School

The nice weather is going to carry on basically through the rest of the week, with a slight chance for showers Wednesday. It will be partly cloudy, with temperatures warming to the mid and upper 50s each day and dropping into the 30s at night. Beautiful days.

GFS model (American) depiction of developing blizzard

While we bask in unusual warmth, an early season blizzard will wind up over the upper great plains. The arrival of the storm will herald a pattern change, from warm and fair to cool and possibly stormy. The incoming storm's cold front will sweep warm air out of the way but bring little in precipitation on Saturday. As the storm progresses east across Canada, another storm spinning off the coast will be drawn back west. As these two storms merge, bits of energy will be thrown off. Mix that with cold air and you got snow. Currently, the three main global models, the GFS, ECMWF, and GEM handle the interaction differently. It's a complicated dance. One misstep and the end result is different. Since the storm is still 7 days out, details are bound to change. The only shred of certainty is that the storm has consistently showed up around the same time period, albeit in many forms. Models are converging on the idea of a powerful blizzard over the plains and moving into Canada. The bottom line is that there is potential for a active and possibly snowy Sunday and Monday before Thanksgiving break starts.

GFS  Model's prediction for strong blocking over Greenland next Tuesday, November 22, 2016.

That's only the 7 day forecast. Models run out to 2 weeks (lol). In that timeframe, one can only consider large scale patterns. Models are indicating that a blocking high ("blocking") that is going to set up over Greenland after this storm. The block forces the jet stream to bend northwards there, which forces the jet stream to bend south ahead of it, where we are. This brings storms south of us, keeping us cold. In addition, blocking patterns tend to result in slower moving storms. Multiple pieces of energy will swing by over Thanksgiving week. Since it is over a week out, nothing is set in stone. Even the blocking may not set up. However, early indications favor the block.

GFS depiction of 500mb (upper level) vorticity over the next week. The orange flowy things are streams of energy associated with storms. Storm 1 is the blizzard and storm 2 is a storm that will develop off the east coast and eventually be absorbed by storm 1.

The main focus is the storm this weekend. Since it seems that it will make a run at clearing the proverbial board, anything after would be wrong if this storm does not go as planned. In fact the storm's position over the Canadian maritimes helps set up the block. I will keep you posted if anything interesting (storm/snow) is possible.