If you’re here and reading this, you probably remember that weather is a hobby of mine. I’m a geek that way. (Well, that way among many other ways.) And when it comes to weather, nothing can match the intrigue of winter weather. Severe weather and hurricanes are next in line, but they’re a distant second to winter weather. So, when fall turns to winter, the majority of the posts around here turn into weather-related postings. By no means do I claim to be an expert on weather, nor to even know what I’m talking about. I’m merely a learning hobbyist. (And since when has not knowing what I’m talking about stopped me from talking? That’s the primary purpose of the blogosphere, is it not?)

So, with that in mind, it’s Oct. 1. And the first of October means it’s time to take our first guess at what the upcoming winter has in store. First, let’s take a look back at last year’s outlook:

This winter promises to see plenty of moist air from the Gulf interacting with a fairly strong southern jet stream and several strong shots of cold air filtering down from Canada. The result? An average fall (with a couple of real nice cold shots by late October and into November), an average to slightly-below-average winter, an early spring, and average to slightly-above-average precipitation throughout. The fall severe weather season (in late October through November) could be a little more active than normal. And, while there’s nothing to suggest a significantly cold winter for the Midsouth, there’s also no reason to think that this won’t be the year when our “snow drought” comes to an end. I think we’ll see our largest winter storm since 1998 (which isn’t saying much since we haven’t had a major winter storm since the big one), and local schools will use more snow days than they have the past several winters.

So how did I do? The results were mixed.

1.) We did see the early-season cold shots. Remember the record-breaking cold of the weekend before Thanksgiving? I remember all too well the Oneida-Greenback football game where temps plunged into the teens by the fourth quarter, and sitting in a tree stand on the opening day of gun season the following morning with ice clinging to all the trees. October and November wound up around three degrees below normal, while December was one degree above normal.

2.) We did see an average to slightly below-average winter. January’s average temp was 31.6; the norm is 33.5. February was 38.0; the norm is 37.0. We didn’t really see an early spring, but we did see slightly above-average temperatures in March and April. We did see slightly above average precipitation through the winter on the whole. Most notably, December was nearly three inches above normal, while February was 2.5 inches below normal. January was more than an inch above normal.

3.) We didn’t see an overly active fall severe weather season, contrary to many La Nina autumns.

4.) We did see an absence of significantly cold winter temps, but we didn’t see our “snow drought” come to an end. We didn’t see “one of our bigger winter storms since 1998.” The storm was on the table, but wound up dumping 14-18 inches in parts of West Tennessee.

5.) Local schools did use more snow days than they had in winters past, using up their allotment of free days and having to make up a day or two.

Enough of that. Time to look ahead to the upcoming winter. If you get bored, skip ahead to the end.

There has been a lot of buzz about El Nino developing and what it means for winter temperatures and snowfall in the eastern U.S. Readers of the Drudge Report doubtlessly saw the article he had linked earlier this week suggesting that the upcoming winter may be the coldest in a decade in the Northeast.

There are several different factors that we can look to for some indication of what the weather will be like. The first is the state of the ENSO (El Nino-Southern Oscellation). More on that below. It can be pretty well determined well in advance. The second is teleconnections across the hemisphere. These can be reasonably guessed at months in advance, but don’t become a sure bet until weeks or even days in advance. And then there are the mesoscale factors: All the little things that go into a winter weather outbreak. And those details, of course, aren’t clear until days before the events begin right up until after the events have already begun. So, while I would like to think that this is a little more than just standing back and throwing darts at a board and seeing where they stick, anyone who hazards a guess at what’s going to happen months down the road (including the professions who, contrary to me, really do know what they’re talking about) is doing just that to a certain degree: Guessing.

EL NINO
El Nino (hereafter referred to as ENSO) is a warming of the ocean currents in the Pacific. It is opposite of La Nina, which is a cooling of the same. The ENSO enters the warm phase about every 3-5 years. Last year was a La Nina winter, and we transitioned to Nino during the summer.

For our region, ENSO’s warm phase typically means wetter-than-usual conditions, due to the southern branch of the jet stream becoming active. On average, we’re more likely to be mild than cold during Nino.

With that said, we have had some classic winter weather events and some memorable winters during the ENSO’s warm phase. Of all the ENSO stages — strong La Nina, moderate La Nina, weak la Nina, neutral, weak El Nino, moderate El Nino, strong El Nino — many of our stronger winters, in terms of frozen precipitation, have been in near-neutral conditions (weak Nino to weak Nina). This seems to be the best range for winter weather in the Southeast, while moderate ENSO stages (Nino or Nina) are somewhat up in the air and strong Ninas/Ninos are usually unfavorable for winter-type conditions.

Recent El Nino winters include the following (with strong El Ninos astericked): 2006-’07, ‘02-’03, 1997-’98*, ‘94-’95, ‘91-’92, ‘86-’87, ‘82-’83*, ‘76-’77, ‘72-’73*, ‘69-’70, ‘65-’66. One of our biggest single-day snowfalls in Oneida occurred during a moderate El Nino winter (1966, 10 inches). None of the other “big ones” in Scott County occurred during El Nino, with the exception of the monster storm in 1998. Of the top 20 snowiest winters as recorded in Nashville, only one of them since 1960 has occurred during a Nino year.

It isn’t written in stone yet, but it looks as though the El Nino phase this year will wind up being moderate during the coming winter. A little less than ideal for the snow hounds, but better than a strong Nino.

So, what we can take from all of this is that strong ENSO stages are bad for winter weather, while weak-to-moderate ENSOs are often unmemorable but do produce more snow and cold temps than some other phases. But nothing is written in stone with ENSO. The winter of 1998 was the strongest El Nino in recorded history, and it brought the northern Cumberland Plateau its biggest winter storm on record. Even when El Nino is well established, things like whether it is “east-based” or “west-based” (defined by where the warmest waters are located in the Pacific) also helps determine what our weather will be as a result.

In short, El Nino gets all the talk this time of year because it’s the one ingredient of the forthcoming winter that can be predicted with relative ease in early fall. But there’s much more to weather than the ENSO.

TELECONNECTIONS
Some of those other factors that will come into play as the winter progresses are more medium-range factors: Mostly, the various oscellations around the Northern Hemisphere that help steer our weather. Among them are the North Atlantic Oscellation (NAO), the Artic Oscellation (AO), Pacific North American (PNA) ridge, and Pacific Decadal Oscellation (PDO). There’s no point in going into further detail about those at this point. Lots of good reading on everything weather-related can be found on meteorologist Jeff Haby’s website. It’s highly recommended. But it might as well be said that the right combination of these various teleconnections can help steer cold air and storms into the Southeast, while the wrong combination can keep us rather mild during the winter months (if you’re a fan of mild weather rather than cold weather, reverse the “right” and “wrong” designations). In the most basic of terms, if the Atlantic is negative and the Pacific is positive, that typically means good things for winter weather fans in the Southeast.

Of the lot, the NAO may have the single biggest influence on our weather, of all the teleconnections. Often times, we don’t know if the NAO is going to go negative (signaling a block of cold air’s return to the Pole and increasing the likelihood of colder air filtering into the Southeast) until days or weeks in advance. But history can offer us some indication of what to expect. As we speak, the NAO is trending negative. It is expected to flip back to positive by mid-October, however. A -NAO in October is not unusual. In fact, it happens quite frequently as summer transforms into autumn. The question is whether it will “lock” into its negative state. A -NAO has occurred in October and November only six times since 1990. Of those six times, it wound up being negative in January as well (when most of our snow occurs, and, thus, a -NAO is most beneficial to the snow hounds) three times, and wound up being positive in January only one time. On the other hand, if the NAO goes negative in October but then trends back positive for November, the likelihood goes up significantly (from a historical standpoint) that it will be positive when January rolls around. So, by mid-to-late November, the winter picture will begin to clear up a little more.

MESOSCALE FACTORS
Then, of course, there are the mesoscale factors — those small details that often aren’t known until a few days in advance, at best. Exactly which path will the storm track? Will there be an area of high pressure sufficiently placed in the upper Midwest to help pull down colder air from Canada?

If the sea surface temperatures in the Pacific Ocean — the ENSO — were all that mattered, meteorologists could tell us right now what to expect in the winter ahead. If the teleconnections were all that mattered, we would know a couple of weeks in advance what to expect. But it’s the mesoscale factors that ensure forecasters will be lucky to get the forecast right seven days in advance.

THE SUN
This is another ingredient that could be factored in. I’m not going to discuss it because, quite frankly, I don’t understand it. In fact, it’s exact impact on our weather is still a subject of much debate. We’re in a solar minimum, with few sunspots, and the general theory is that a decrease in solar flares leads to a decrease in global temperatures. (In fact, the Maunder Minimum — a prolonged period with very little sunspots in the Middle Ages — corresponded with the Little Ice Age.)

LOOKING AHEAD BY LOOKING BACK
So enough on what we might see moving forward. Let’s look at where we’ve come from. This summer has been unusual: First, because it has been so cool and wet for much of Tennessee, but also because it has been so consistent. Since the big heat wave in late June, we have been mostly below-normal in the temperature department, with only a sporadic day here and two days there where temperatures climbed above normal. There has also been plenty of precipitation, while the heat has been mostly limited to the West and Southwest portions of the country.

Will this continue? It’s hard to tell. And you can’t try to answer that question without looking at the above-mentioned factors a little. But we can look back at a little history. The last time we saw a summer that was, on the whole, similar to this summer was 1977. And what followed that winter was the seventh-snowiest winter on record in Nashville (with records dating back to 1894). A little more than 25 inches of snow were recorded in Nashville during the winter of ‘77-’78.

THE BOTTOM LINE
This has all probably been too jumpy and rambling to make much sense, and it leaves out a whole heap of details (more rambling) for the sake of brevity. But, strictly for entertainment purposes only, here is the bottom line on this winter: Average to slightly below-average temperatures, on the whole, with more days featuring below-average temps than days featuring above-average temps. Our weather will be dynamic, with a number of storm systems. Thus, the wetter-than-normal conditions will continue, but the surplus won’t be as significant as it has been this summer (which saw a foot of rain more than normal here on the Plateau). We will have a 75% chance of seeing total snowfall exceeding 10 inches. There will be a few nor-easters that will turn into a blizzard or two for the Northeast. Closer to home, there should be enough potential for at least a couple of blockbuster winter storms. But where they set up at is the question. Will they go west of us (as they have the past two winters)? Will they go east of us? South of us? Only time will tell. We’ll revisit in 6-8 weeks and see how it’s shaping up.

What others are predicting:
Accuweather.Com
Farmers Almanac
NOAA’s Climate Prediction Center