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Winter Has Begun! So Will It Stick Around?

BOSTON (CBS) - We're all waking up to our first glimpse of wintry weather so far this season. It took a while, but nature starting matching up with the calendar. Quite the mood swing too, from 70's in spots last week to an icy mix today.

This begs the question - is it a fleeting glimpse, or just 'coming attractions'?

A bit of both, but don't expect January to look much like December.

2015 Calendar December(1)2015 Calendar

In the short term, the final few days of the month will still be above average, believe it or not. Even Monday was by a couple degrees. I find this absolutely remarkable, because we saw two of the craziest winter months ever recorded in the Boston area - in the same year! This December has been almost an EXACT mirror image of February, right down to the fact that each had only one day above/below average, and both of those were by just 1 degree. Kinda creepy when you think about it. February was the coldest month ever recorded in most of New England, and this December has been the warmest winter month ever recorded for most of New England. Polar opposites in the same year. Boston will likely reach 40 today, and into the 40s Wednesday and Thursday.

coldstuff

Now that's a winter air mass! Sunday into Monday, temps will dive into the -15 to -20C range at 850mb. That will produce the first widespread day of below average temperatures we've had in quite some time. Source: Weatherbell

Then we look toward the medium range. Cold air will pour on down out of Canada this weekend, much to the delight of the ski and snowboard crowd. Not much in the way of additional snowfall outside of a few snow showers, but temps will stay in the 30s this weekend (highs) and may get stuck in the 20s on Monday to start next week. Great for snow-making, although that's definitely not unusual for early January - just a few degrees below average. But a big turn-around from December. Most of next week looks dry and pretty close to average.

longrange

It's toward mid-January that things get interesting. We've been monitoring a likely pattern shift, which is looking more likely by the day. The most recent long-range guidance (like the ECMWF weeklies) are indicating a change in teleconnection phases. Teleconnections are ways of diagnosing the atmosphere on a large scale. You may have heard of some of them, like the NAO (North Atlantic Oscillation), the PNA (Pacific North American Pattern) or the AO (Arctic Oscillation). Things snow lovers like to see around here: a +PNA, a -NAO, and a -AO doesn't hurt either.

ao

Well all signs are that we'll finally move toward a -AO as we turn the page to January, and the PNA will spike positive as a ridge builds up along the West Coast and western Canada. This allows more cold air to flow down into the Lower 48, and a trough digs into the east as a downstream response.

pna

The bottom line is that conditions look favorable for increasing East Coast storminess toward mid-month, in particular the January 10-14th time frame. It's one to watch as we await the first true winter storm of the season. Of course, these things always come down to a delicate dance of exact timing when it comes to cold placement, storm track, etc. So we can't really say 'there's going to be a winter storm on January 12th' this far out. But the odds show this to be a volatile period for us to monitor, and the next real shot at some actual snowfall.

After that, guidance shows the +PNA breaking down and a trough digging back in to the Gulf of Alaska, so this may be a brief stretch of cold and possibly snow before a return to milder conditions. That's looking a long way out, but it's some weather geekery to put on your radar for the weeks to come!

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