ROANOKE, Va. – Forecasting an entire season is very challenging, and lacks the precision of a day-to-day forecast. However, the number one question we get from viewers even since the summer is, “What do you think this winter is going to be like?”
Caveats
• As mentioned, seasonal forecasting hasn’t quite caught up to the success of a day-to-day forecast. After all, meteorology is an inexact science.
• We do not take into account what other TV stations say, nor do we use the Farmer’s Almanac or things like the wooly worm (nothing against those who do). This forecast, successful or not, is ours.
• You may see some differing opinions on this winter because the signals in the atmosphere aren’t as clear as they might be in other years. We’ll discuss that farther down.
• A single, over-achieving storm can alter the results of a seasonal forecast (similar to what you hear with tropical forecasts).
• "Below average” does not mean “no snow.”
What is the “average” snow for a season?
***This is not the forecast.***
Elevation clearly plays a role when it comes to snow in our area. Average snow for the Highlands and New River Valley is about two feet (higher on mountain tops). The average for Lynchburg to Roanoke is about a foot and a half, whereas Southside sees less than a foot.
Region-by-Region Snow Forecast
Now that you know the averages, here’s our forecast for each region:
New River Valley
We’re forecasting a near-to-above average snowfall this winter in the NRV, due to more frequent clipper systems. These clippers tend to favor more snow in higher elevations. Areas like Whitetop/Mount Rogers and Mountain Lake may wind up seeing more than the 20-26″ advertised.
Highlands
Similar to the New River Valley, we are forecasting a near-to-above average snowfall in the Highlands due to more frequent clippers. Areas like Snowshoe or the Blue Grass Valley will likely wind up with more than somewhere like Covington due to elevation.
Roanoke Valley
For the purpose of this forecast, we’ve lumped Lexington in with the Roanoke Valley. For this part of the area, we’re forecasting a near-to-below average snowfall this winter.
Lynchburg & Central Virginia
Similar to the Roanoke Valley, we expect near-to-below average snowfall this winter in Lynchburg and Central Virginia.
Southside
Lastly, we expect a near-to-below average winter, snowfall-wise, in Southside.
Three Main Ingredients Used
When putting our winter forecast together, we look at three main patterns:
- Siberian snow cover. It can influence how much cold air drops into the Eastern U.S.
- El Niño or La Niña (how warm or cold the water is off the coast of Peru). These can influence the frequency of storm systems in the Southeastern U.S.
- How much energy is spent by the tropics? This can determine whether or not the winter needs to make up for an imbalance.
El Niño & La Niña
The El Niño Southern Oscillation (ENSO) is a key component of seasonal forecasting in this part of the world and it comes in three phases.
- El Niño refers to warmer waters off the coast of Peru, which typically translates to wetter weather in the Southeastern U.S.
- La Niña is the exact opposite. Cooler ocean waters off the coast of Peru typically lead to drier periods in the Eastern U.S.
- Neutral means that the waters off the coast of Peru are neither warmer nor colder than average.
Currently, the ENSO is in its neutral phase. Historically speaking, that doesn’t tell us much about how much snow we could see. Forty-four percent of winters spent in the neutral phase have been snowier than average, whereas 56% of winters haven’t.
Tropical Influence
The amount of energy exhausted during the tropical season can influence what happens in the winter. When tropical storms or hurricanes form, they send heat/energy to the poles. The atmosphere wants to stay in balance. So, if the tropics spend a ton of energy, then the winter won’t have to make up for it by generating more storms (and vice versa).
This year, the amount of energy spent in the tropics has been close to the 40-year average. Unfortunately, this doesn’t give us a clear tell-tale sign of how many storm systems there will be this winter.
Siberian Snow Cover
How much snow Siberia gets in the fall and winter can influence how many cold air outbreaks we see. We’ve seen this play out already in November.
Snow reflects light into the layer above us, the stratosphere. When the stratosphere warms, the wind in the Arctic relaxes. That allows cold air to plunge farther south.
In recent weeks, the snow cover in Siberia has expanded quickly. This leads us to think that the first half of winter will be colder than the second half.
Closing Notes
When looking for years that have had a neutral ENSO phase, average tropical activity and a similar amount of snow in Siberia, we find a limited sample size. In the three similar years, snow has mostly been at or below average for our area. The exception to that is in the higher elevations, like the NRV and Highlands.
It all comes down to the individual storm, which cannot be forecasted weeks to months in advance. In order to get snow, we need cold air and moisture to sync up.
We will get cold this winter and most of us will get snow at some point. We just don’t see any blaring signal for an exceptionally cold or exceptionally snowy winter.
We hope you have enjoyed reading and listening to our winter outlook. Have a great Thanksgiving week!