Long range forecasting is inherently flawed and is not easy to execute, but that being said, we can see trends and give you an overall idea of what to expect. Here’s what we are looking at toward the fall and winter of 2017-2018.
Right now NOAA is going with a slightly warmer and drier set-up for us this winter, given the weak La Nina in the forecast. Here's a look at what La Nina means for our area and what I'm thinking at this point...
La Nina conditions are expected this year. but it's not a done deal. La Nina is the opposite of El Nino, as it brings cooler than normal waters to the equatorial Pacific Ocean. That translates to a less active storm pattern for us, along with a “warmer” winter, but let me explain that a little further.
During El Nino, we see cooler temps on average because of increased cloudiness and rain/snow chances. During La Nina, we tend to see clearer days, and ultimately warmer than average temperatures. However, La Nina can bring some strong arctic outbreaks. We can see clear skies during the day, but only reach the 20s for highs. So don’t expect La Nina to bring mild temperatures all winter long.
As for rain/snow, we’ll probably see less than normal for our winter if La Nina does set up. In that case we wouldn't get a very active subtropical jet stream like we see during El Nino years, and that is what often brings in our big snowfalls and ice storms. We can still get big snows in La Nina, in fact March of 2009 is a great example of that. The storm systems are just less frequent.
Last winter was a La Nina winter, and we did see warmer than normal conditions (in fact it was the warmest February on record!), however there was a big snow event in early January bringing 3-5” for much of the Upstate along I85 and north. Then we got a final dose of snow that didn’t stick around long in March.
When you look back at the biggest snow events and snowiest winters in our area, only 1 of them correlates to a strong La Nina year (1971-with 11.4” of snow in the Upstate).
So, it will potentially be a quieter winter for snowfall, but we could still see one or two big events. We’ll keep monitoring conditions and keep you posted as winter approaches. We'll also be watching other teleconnections like the North Atlantic Oscillation (NAO) through the season and will keep you posted on any big cold snaps coming!