We study various “signals” when forecasting for the winter season. These signals include ocean temperatures in the Pacific and Atlantic waters, air pressure differences in the North Atlantic Ocean, snow cover in Siberia and, for this year, La Nina. La Nina is the cooling of ocean water in the equatorial Pacific Ocean (to the west of South America). All of these worldly players can have an influence on the type of weather we will have in Pennsylvania over the next several months.

This year, a weak La Nina is forecasted. Generally, it’s the main driver when it comes to our winter weather. Let’s break things down by talking about temperatures, storms and snow.

Overall, this winter is expected to have near-to-slightly above average temperatures. In addition, this pattern will lead to big temperature swings. It could be in the 50s on week, but drop into the 20s and 30s for the following week. These shots of cold air will certainly get into Pennsylvania. However, they won’t last long. This is what we call transient cold air masses.

Now that we’ve handled temperatures, let’s move to the active weather pattern that we’re forecasting. This winter will bring frequent storms. They’ll range in strength from multiple weaker events to the potential of a couple of Nor’easters along the coast. Because of the transient nature of the cold air, it won’t always be in place when these storms arrive. In turn, the phrase “wintry mix” will likely be said a lot this winter.

Even with the cold air coming and going and these wintry mix events, we’re still forecasting slightly above average snow for this season. One reason is the frequency of storms will allow a couple of inches here and there to add up through the season. In addition, the pattern will lead to an opportunity for a couple of bigger coastal storms that could put down a healthy dose in a single shot. For more specific snow forecasts, make sure you watch the Eyewitness Weather Winter Outlook video. Generally, we’re thinking snow totals about 20% above average this year.

Of course, this is an outlook and the possibility exists that all of the signals won’t play out as expected. One thing we’ll have to watch is the development of La Nina. The key is where the coolest water will be established and where thunderstorms develop in the tropical Pacific. These details, even though they’re thousands of miles away, can significantly impact our winter weather.

–Your Eyewitness Weather Team (Josh Hodell, Dave Kuharchik, Stefano DiPietro, Dave Caulfield and Kevin Derk)