2017-18 Preliminary Winter Forecast


Everyone remembers the brutal winters we faced just a few short years ago. The winters of 2013-14 and 2014-15 were just downright cold, with a good amount of snowy days. But the last two winters have been the exact opposite. The winters of 2015-16 and 2016-17 were quite toasty around here, with very little snow at all last year. In both of those years, winter seemed to show up for a few days and it was very warm otherwise (for winter standards). But what about this upcoming winter?

While I don’t think this winter will be quite as warm as we’ve seen the last two winters, the data leads me to believe that we are heading for yet another reasonably mild winter. I will discuss them in some small detail here in this post. Be sure to watch the video discussion at the end if you want a more in-depth analysis of the factors at hand.

OCEAN CONDITIONS

You’ve likely heard by now that we could be in for a La Niña this year. La Niña is an abnormal cooling of the water in the equatorial Pacific between South America and Australia. To be considered a La Niña, we need to see temperature anomalies of -0.5°C for three consecutive months. We are near that threshold right now, but it needs to stay that way for a good while to become official.

At the time of this forecast, we are at a -0.4°C for the daily value. You can see below where it has been up and down. We’ve been cooling for months now and the trend is toward La Niña. The question is whether it ever becomes official or not.

The latest modeling does give us a weak La Niña as we go through this winter. Some data suggests it could be a strong one, rather than weak; but that data only comes from one or two unreliable models. A weak La Niña is favored. A word of caution, though. This time last year, we were looking for the same thing and it didn’t pan out. In fact, the waters actually warmed and we came nowhere close to a La Niña! Could that happen again? Time will tell. I think things are more lining up right to develop it this year, but there is always that chance.

Why does this matter? La Niña winters tend to feature a warm and wet regime here over the Ohio Valley. The stronger the La Niña, the warmer and wetter it becomes. Weaker ones can still give us some cool shots from time to time, but strong ones lead to very warm winters with little to no cold and snow.

ANALOGS

One of the best methods of forecasting is to dive into some analogs, past years with similar ocean conditions. By using analogs, we can see what the weather was like in previous winters with a similar ocean temperatures. If you’d like a more in-depth discussion of these, watch the video at the end.

The analogs suggest this for temperatures this winter. This would give Southern Indiana a near normal to slightly above normal winter for temps. If I were to err on the side of caution, overall mild temps seem very likely at this point. That’s not to say we won’t see any cold air invasions. We usually do. But the theme will be more mild than cold when it’s all said and done.

Precipitation has a strongly above normal signal in the analogs this time around. Caution: this does not mean more snow. In a warm winter, this would mean lots of rain. That doesn’t mean it won’t snow. It likely will. What we saw last year was way abnormal for snow. Will that repeat itself? I sure hope not. This snow lover was really depressed about last winter! I do suspect we’ll see more snow this winter than we did last winter. But given the overall mild temps, a mega snow winter probably isn’t likely either. After last winter, I’ll take what I can get. Less than two inches in one single event all season for me was a real let down.

SEASONAL MODELS

What about the seasonal models? There is actually some decent agreement between the modeling and the analogs. The JAMSTEC model below is the most reliable of the models we have. You can see it’s in pretty decent agreement with the analogs I showed above. This helps yield a bit more confidence than in some years.

There are several other models that yield similar ideas. I discuss these one by one in the video below for those that want to dive more into this. In the video, I go through 7 different seasonal models for my fellow winter junkies and you’ll get a better perspective of what they are saying.

SNOW TOTALS

Let’s look at snow totals a bit more. The analog years I’ve chosen yielded the following for snow totals in Evansville, Indiana. You can see that they really ran a broad spectrum. Some years saw next to nothing! Some years were loaded with snow. A word of caution, those years that were loaded with snow came as a result of a big snow storm and doesn’t necessarily mean the whole season was snowy. Overall, 5 seasons featured above normal snowfall, 6 seasons featured below normal snowfall and 1 season was near normal. What does that mean? Well, it means we could have either extreme. Mega storms could be possible (I said possible, not likely). But years with next to nothing are also possible. Notice 2011 below with only a half inch all season! Or 1956 with a whopping 2.6 inches. So yes, next to no snow is very possible. So are decent totals. What I can say is La Niña will likely limit our snow chances due to less frequent cold air invasions, so to get those larger totals, we’ll need bigger storms. Those are hard to come by around here!

MY THOUGHTS

Here are my preliminary thoughts on this winter. Look for most of the cold to stay to our north and well to our west this year. I highly suspect when it’s all said and done that we will see an above normal winter again for temperatures. That’s not to say that we can’t have a few cold snaps. We certainly could and probably will at times. But I do think those cold snaps may be few and far between this upcoming season. I think we’ll be way more mild than we will be cold.

The data also suggests to me that we will see what could be an above normal amount of rain this winter. The data suggests an active storm track through the Ohio Valley this season and that will likely lead to quite a bit of rain this winter. Maybe some snow? Meanwhile, the deep south looks to be below normal this winter, as well as the west.

As for snowfall, here are my early thoughts. I do suspect that we’ll be below normal here in the Ohio Valley. The above normal snows will likely be way to our north where the cold will be more common. Look for far more rain events than snow events for us this winter. That’s not to say that we won’t get any snow. It was toasty last winter and we did have 1 snow event. I suspect we’ll see more snow this winter than last, but that’s not saying much.

Here are some highlights for Southern Indiana. While cooler than last winter, expect above normal temps, above normal rain and below normal snowfall again. My rough estimate is 50%-75% of normal snowfall this year. Last winter only saw far less than 25% of normal, so it would be an improvement, at least, for you snow lovers. But unless the stars line up just right for a miracle, I’m not seeing a tremendous snow year this time around.

My Final Winter Forecast will come out on December 1st! Be sure to watch the video below for a more in-depth explanation of all the above.