It is coming

We've had a nice period of cold, but what is really normal, weather. A brief warm up began today and will continue to highs around 60 tomorrow. However, there is a growing indication from a number of models that the real turn to cold is near. And as predicted in my winter outlook, it will begin with our first real chances for snow, and possibly even accumulation between the 5th and the 10th of November. The pattern change schedule is as follows:

Frontal system swings through Thursday afternoon bringing 850mb temps below 0C by evening. High pressure moves south. Meanwhile, we watch the track of TS Noel and the resulting potential extra tropical monster.

Noel, currently a moderate tropical storm will enter the Atlantic Ocean east of Florida. It is then picked up by the frontal system that moved through on Thursday which at that point will have retrograded northward west of blocking high pressure. Whether or not the storm hits New England will not have any implications on the pattern shift, only whether or not we get pounded by heavy rains and gale force winds.

The extratropical storm moves out ahead of the Thursday system positioning near 50/50. The set up now begins the drop in the NAO, allowing a more amplified pattern to ensue and colder air to spill south. Beginning the middle of next week, 850mb temps under -10C will reach into SNE.

This leads us to our first chance for snow. Sunday Night into Monday morning, 850mb temps drop to around -3C. Surface temperatures near freezing, and 500mb thickness around 534dm. Models indicate a clipper moving southeast across the region. In a winter situation given ample frontogenisis, this could be a 2 to 5 inch event, but with a warm ground and a smaller thickness gradient, accumulations would be more minimal. However, accumulations could occur, and based soley on what is being suggested right now, a coating to an inch of snow is not out of the question on Monday. There are some timing issues between models. GFS puts the shortwave over the region on Sunday, while the Euro is about 18 to 24hours ahead. At this point in the game it is just nice to have all the models showing something. Currently this forecast is 120 to 144 hours out, so still room for notable changes.

The second event is the middle to end of next week. Low pressure moves through the Great Lakes and across southern Quebec. Frontogenisis across New England sets up a .25 to .75 QPF event. Colder 850mb temps and larger gradient could help in delivering a 2 inch event to the interior northeast.

All in all, more credible possibilities are starting to develop. A -NAO and +PNA regime is likely for at least the start of November. With the +PNA more likely to hold strong through the entire month. Count on a cold month ahead.