BOSTON (CBS) – It may have been winter for the past couple months inside your local big box store’s seasonal display area, but the real deal is upon us.
Leaves have nearly given up, a Thanksgiving road trip may be on the calendar next week, and Mariah Carey will promptly take over the air waves by the time dinner wraps up.
Let’s not start this off on false pretenses – seasonal outlooks are far from perfect. We use the best tools available given the technology and research at hand, and come to educated conclusions on what the winter may bring.
Darkness? Check. Cold? Check. Snow? Check.
Now that we’ve gotten the easy stuff out of the way, let’s take a peek at the factors that will play a role in our next few months.
#1 No ‘Return of the Torch’
Will it be colder than last year? Yes. That’s a pretty safe assumption.
Last winter barely even started until mid-January with an extraordinarily balmy December and barely any snow at all. We actually got the worst of winter in April, and it ended up as the second warmest winter ever recorded in the Boston area.
While this wasn’t very tough to take, it actually did more harm than good for our local plant life. A solid period of dormancy is good for our perennial greens-blooms, and we never got it. Plus, moths. So many moths.
This winter is not expected to resemble 2015-16 in the temperature department.
We are thinking that cold intrusions will arrive earlier (our first in the forecast arrives Sunday!) and that December will bring some snowfall where last year did not. That being said, our team’s belief is that temperatures will end up very close to ‘average’ when smoothed out across the season. We’re not seeing a deep period of constant cold, or a persistent torch developing. More of a give-and-take winter that will bring us cold blasts and intermittent relief. After the past few winters, this might actually be a welcome change! We went from very cold to insanely frigid to eerily warm. A more traditional New England winter is due.
#2 El Nino Out, La Nina In
A big reason for last winter’s warmth was an extremely strong El Nino event.
Every strong El Nino on record has produced above average temperatures in the Boston area. But those waters of the equatorial Pacific have cooled off dramatically, and we now have the opposite – La Nina. It’s a weak La Nina, and isn’t expected to linger for long. But the strong Pacific forcing that in turn pumped up constant ridging-warmth in the U.S. last winter will not be a significant player.
Most weak La Nina years have produced near or below average snowfall here. However, there have been a couple of monster exceptions (like the previous record snow winter, 1995-96).
La Nina helps to favor colder times across the northern states, especially from the Upper Midwest to the Great Lakes. Results here have been mixed. And although it’s a small sample size, we have never picked up more than 60 inches of snow in Boston in the winter following a strong El Nino.
#3 Where Will The PDO Go?
Another big variable we look at is the PDO – the Pacific Decadal Oscillation.
This is a pattern of sea surface temperatures that often locks in to 20-30 year cycles, with a few aberrations mixed in from the general theme.
Our coldest and snowiest winters come when the PDO is strongly positive (8 of the top 10 of both on record) and our warmest typically come when it is negative (all of our top 10 least snowy came during a negative or neutral PDO).
The PDO was extremely positive in 2014-15, which is one of the main reasons we issued such a frigid and snowy outlook for that winter (jackpot!). The other major snow year for us, 1995-96, which also happened to be a weak La Nina winter, featured a positive PDO as well.
This winter, it’s a bit of a wildcard.
The most recent index has dropped down to negative status, though there has been massive and rapid cooling of the North Pacific and a trend back toward a +PDO. In my mind, you need to bank on a +PDO returning to start thinking about a monster snow year.
#4 I Keep Hearing About Snow In Siberia…Why?
You may have heard or read about the SAI, if you’re a big time winter nut. The SAI is the snow advance index, pioneered by Judah Cohen at AER.
It’s a measure of how quickly snow cover builds up across Eurasia in the autumn, and this year featured an intense barrage of cold and snow in October (a record high run-up). This can be important, because it helps to build a strong Siberian high pressure system, which in turn can help weaken the polar vortex (yeah, that polar vortex) and help to allow arctic air to plunge southward away from the pole.
So far this year, all that cold has been sitting over Russia and parts of Europe while the Arctic and North America have been on fire (relatively speaking). But eventually, the weaker polar vortex should allow some of this cold to come visit us state side. This is another reason why we believe a very warm winter won’t be able to materialize.
#5 Tell Me About SNOW
The section you’ve probably been waiting for, right here. Let’s talk snow totals.
It’s extremely difficult to nail snow totals for a season across an entire region. It comes down to exact storm tracks that frankly, we don’t have skill in knowing. One big storm or a big miss can throw everything off. But, as I mentioned at the top of this post, we can make some educated guesses.
We believe above average snow will return to southern New England this winter. Rejoice! Or rage! Whatever works for you.
The presence of colder air this winter and the expected return of the ‘Alberta Clipper’ (where have they been the past few years?) will help us boost totals from last year’s meager season. Plus, the colder temps will help it stick around longer. However, we’re not expecting a massive season like two years ago.
The current thinking is for snow totals in the 50’s (inch range) for Boston, the 70’s for snow belt regions north and west of the city, the 30’s for Cape Cod, and a MUCH better season for ski areas.
You can’t really nail mountaintop forecasts for snow, but we believe there will be a healthy dose to go around this winter and that skiers and snowboarders will be much more pleased. Also, easier conditions for snow makers to go to work without a parade of rain storms to muck things up.
#6 The Drought – What Do We Need?
The number one question we get from people when talking about the drought is “What about all that snow two years ago?”
The long and the short of it is that the winter of 2014-15 was so cold that all of our storms were powder. There was barely any water content in that snow – you could move it off the driveway with a leaf blower. So that winter actually had average-to-below average water equivalent, even with record snow totals.
The reality is that we’re in the worst drought since the 1960’s in southern New England (excluding the Cape, Islands, South Coast, and Rhode Island).
If you track things back 5 years, the deficits are in the 24-to-40 inch range. That’s two-to-four FEET of missing water, and it’s not a gap we can make up easily.
It would be great if we got a stormy winter that featured some wetter snows and rain mixed in with a bit of powder. We really need to hope for above average precipitation, otherwise we’re going to be in a tough spot come the following spring. It’s not so much the short-term drought, but the fact that this has gone on for so long that water tables are very low and reservoirs are drying up.
If we got the wettest December-March in the record history of Boston, that would just about make up the deficit for ONLY this past year. It wouldn’t even touch the deficits for the other four. That’s how much we’re talking.
Now we don’t need it all at once, or in one season. But it is in our best interests that a stormy pattern evolves and leads us through next spring, before the heat of summer kicks in. But that’s an outlook for another day.
WATCH: Web Extra Of WBZ-TV Weather Team Winter Discussion