To be perfectly candid, there's not a lot of positive news on this first Friday of 2017. First, the terrain enhanced snow that we had hoped would redeem the wintry mix from a few days ago never really materialized. That is certainly a bust I have to fess up to before discussing anything else. Though the cold is firmly entrenched across New England, this grip will become substantially more tenuous next week and the various indices are not expected to move in a good direction beyond that.
In the short term, a significant winter weather producer across the southeast will evolve into snow producer for eastern Virginia Saturday and move off the coast over and pass over 100 miles east of Cape Cod. The system might bring snow to the Cape and Islands but will not bring its moisture to interior sections of New England. Saturday will just turn out to be dry and chilly with excellent visibility and temperatures in the teens. Light winds will make conditions tolerable for January. On Sunday, temperatures will be similar and a weaker weather disturbance will bring some light snow to the region during the ski day. About an inch or two is the most we can expect from this followed by a chilly Sunday night.
We could also see some more snow thanks to some overrunning moisture as warm air begins to erode at the cold across the U.S. from southwest to northeast. Sporadic periods of light snow should be expected between late Monday and most of Tuesday into Tuesday night. Most of the accumulation from this will be Tuesday night just before things take another potential adverse turn in Vermont.
Indications were that we were slowly headed in the right direction again in spite of the persistently negative PNA. Over the last two days, the big development in the forecast models and ensembles has been the expected tightening of the jet stream in the Pacific. Anybody that has followed the blog over the last several seasons might understand how much I absolutely loathe a tightened and energetic Pacific jet stream. I call these features the "evil empire" so the connotation should not confuse anybody. The index that most closely measures the pattern in the Pacific is the Eastern Pacific Oscillation or EPO. This index, when negative indicates a loose jet in the Pacific and typically allows for arctic cold to penetrate a good portion of the northern United States in January. A tightened jet in the Pacific or positive EPO scours much of the cold out of the United States. Much of the effects of this forecasted positive shift in the EPO is forecasted in the last several runs of the ensembles. Much of the eastern two-thirds of the country will be on the mild side of average and arctic cold will have a very limited influence on much of the U.S. including New England.
In terms of actual weather we already have one potential ice to rain situation for this upcoming Wednesday. This follows the snowfall we are expecting late on Tuesday. Now through most of next week, arctic air is close enough to keep it a little interesting. In spite of this however, temperatures are still expected to climb above freezing Wednesday the 11th. Another systems will follow for later in the week and this also appears to be another precarious situation.
The late week system has a bit more arctic air in the vicinity but the cold needs to be in place or at least available to create a good snow situation for us going into MLK weekend. This is likely going to be the last surge of cold before the arctic chill makes that retreat caused by the aforementioned shifting in the Pacific jet stream. How it interacts with the late week storm or any system that might follow for the end of MLK weekend remains to be seen but at least snow is not out of the question. It is beyond MLK weekend where conditions really start to look mild for New England allowing for the possibility of a dreaded January thaw sometime between January 18th and 25th.
Meanwhile the rich get richer in Lake Tahoe. The last storm ending early Thursday dumped 50-80 inches most of the ski areas there. In typical Tahoe fashion however, many of the lifts were closed due to wind holds and even some of the roads were shut down because of avalanche danger.