With Halloween and the peak of fall foliage in the rearview mirror, the question of what winter might have in store looms larger. The National Oceanic and Atmospheric Administration recently released a winter outlook predicting that winter weather patterns will be affected by the Pacific Ocean climate pattern known as El Niño.
“This forecast suggests both a warmer winter overall and a snowier winter than last year,” said Andrew Ellis, a hydroclimate scientist in the College of Natural Resources and Environment at Virginia Tech. “With a strong El Niño and the potential of a super-El Niño, there is a definite lean toward wetter conditions for winter across Virginia. During El Niño years, wetness is often predicated on an increase in coastal storms that originate along the Gulf Coast states. With that being the case, western Virginia finds itself on the cold side of the storms, so snow chances are greater.”
Ellis answered further questions about what the forecast does and doesn’t predict.
Does the newest NOAA outlook enable any predictions for how much snow is coming?
“El Niño winters are often warmer across Virginia for the balance of the winter, but the increased moisture and coastal storm track increases the chances that cold air finds moisture more frequently to generate a snowier winter overall. This is often from a few larger snowfalls.”
How might climate change affect the forecast?
“It is difficult to imprint the effect of recent climate change on the winter season forecast. Climate change effects on precipitation and on El Niño dynamics are not very clear. The most reliable influence of climate change is an overall warming, but once precipitation is involved, all bets are off because increased clouds and precipitation have an overall negative effect on temperature, thus canceling out the warming effect.”
How accurate have previous winter outlooks proven to be?
“Seasonal forecasting, in general, is difficult, and accuracy is limited. Hence, seasonal forecasts are only slight leans in one direction regarding moisture and temperature. However, the El Niño and La Niña climate phenomena correlate most strongly with winter climate across the United States. During ‘neutral’ years when those phenomena are not present, the forecast is largely a coin-flip for nearly all of the country. However, with this being a strong El Niño year, there is a greater sense of confidence in the winter season forecast.”
Professor Andrew Ellis teaches meteorology and climate science in the Department of Geography within Virginia Tech’s College of Natural Resources and Environment. His research focuses on snowfall variability, understanding and monitoring the occurrence of drought, and assessing the sustainability of freshwater resources in arid and semi-arid climates.