“We don’t foresee another year like this.” Those are the encouraging words South Dakota State Climatologist Dennis Todey is sharing with South Dakota’s ranchers and farmers. While the statement does renew hopes for more normal weather conditions, Todey cautions that 2013 is not likely to bring consistently average temperatures and precipitation.
“There’s no way to determine a definite cause for the weather extremes we have experienced this year,” Todey says. “Often, it’s quite a while after an event like this before we can begin to determine a cause, if we ever can. We are transitioning out of La Nina, which trends toward warmer and drier conditions in South Dakota. However, we know that a persistent, large high pressure ridge parked over the central part of the United States was responsible for our weather pattern. We don’t know why the ridge has been so prominent for so long, but it was the main cause of our weather extremes.”
Statistically speaking, the 2012 growing season has been comparable to both 1988 and 1976, when warm and dry conditions dominated the spring and summer. A few 2012 records surpassed those set in the “dust bowl” years of the 1930s. One difference between 2012 and the dust bowl years is that three extremely hot, dry years occurred within a five- or six-year period during the 1930s.
“Discussions between climatologists often focus on potential for increasing weather variability,” Todey says. “The 2012 season has certainly been a year of extremes. Climatologists’ concerns were raised last fall when very dry conditions at harvest led to fires in the fields.”
The far southeast corner of South Dakota has experienced the most extreme dry conditions, exceeding the driest June-July-August on record by one inch. Conditions have worsened statewide recently.
“All of South Dakota has some level of drought right now,” Todey says. “In the near term, through September, we don’t expect to see much improvement. There are no pattern changes that look like they’ll lead to a bigger, widespread rainfall. As we move into fall, we do expect the pattern to change and to see more widespread rain that will help alleviate some conditions. However, we don’t expect to see dramatic improvements. Cooler temperatures will help because that reduces the amount of water used by plants and crops. We don’t expect rains to be heavy, so they’ll probably reduce us by one drought level. We will see some improvement, but the dry conditions won’t be completely resolved.”
Todey notes that it’s highly unlikely that South Dakota will experience back-to-back extremes like the state just experienced. Growers can probably plan on a more “normal” growing season in 2013. Livestock owners who rely on surface water for their animals may face another year of finding water alternatives.
“The soil is so dry right now that even a two or three-inch rainfall would produce limited runoff,” Todey says. “That means stock dams and dugouts won’t regenerate very quickly. We’ll need quite a bit of snow over winter and normal rainfall in spring to bring back surface water levels. Right now, it doesn’t appear that snowfall is going to be that heavy, at least at the beginning of winter.”
As we transiton out of La Nina, South Dakota is on the edge of entering an El Nino weather pattern, which would mean a warmer than average winter and lower than normal precipitation. Current indications are that snowfall amounts could be heavier toward the end of the winter season.
“Several things can happen yet to affect our winter weather pattern,” Todey says. “I encourage livestock owners and farmers to watch daily weather forecasts and stay abreast of projected weather patterns. I also encourage them, as they make their decisions, not to be overly concerned. It will rain again. Our weather pattern will change and conditions will get better. We just can’t say exactly when that will happen.”
Part of Todey’s optimism stems from the weather patterns seen in the past 4 to 5 years, with precipitation levels higher than average. Historic weather records demonstrate that above average wet weather patterns have been interrupted by brief extreme dry patterns before.
“There’s no scientific basis for that, just the historic averages we’ve seen,” Todey says. “We can’t say that 2012 weather conditions were caused by global warming, but we do know global temperatures are rising. That warming trend creates potential for more frequent droughts. Over the past 30 years most of the warming we’ve seen has been driven by winter temperatures, not warm, dry summers. No matter what happens with our weather, the variability will stick with us.
“In the years ahead, we all need to better understand how to work through seasons of extremes like the one we’re in now,” Todey adds. “We need to make advances in the science used to forecast weather conditions. Climatologists are always examining what global climate models say. It’s difficult to pinpoint specific causes for any one year. We expect to continue to see a warming trend and variable weather patterns every year.”
“The soil is so dry right now that even a two or three-inch rainfall would produce limited runoff,”
- Dennis Todey