BROOKINGS, S.D. - South Dakotans’ apprehension of an impending drought has been growing, and rightfully so, says Laura Edwards, SDSU Extension State Climatologist. According to the latest National Oceanic and Atmospheric Administration climate outlook, there will be minimal moisture reprieve in the months to come.
The U.S. Drought Monitor map released January 21 shows over 60 percent of the state in Moderate (D1) to Extreme (D3) drought categories. The remaining nearly 40 percent is in the Abnormally Dry (D0) category. Three months ago, only 42 percent of the state was in the Moderate to Extreme drought categories.
Edwards says the lack of precipitation recently has made a dry situation worse, as soil and surface water are also evaporating during this abnormally warm winter.
“The lack of snow cover is not able to protect winter wheat from possible frost damage, should areas see extreme cold temperatures,” Edwards says. “People who enjoy outdoor winter recreation have struggled without snow for snowmobiling, sledding and cross-country skiing. Ski areas in the Black Hills have had to improvise, making snow for their runs in order to stay open for business this season. Thin ice on many lakes and waterways has made ice fishing unsafe.”
Last week, the NOAA Climate Prediction Center released its February outlook as well as its three-month outlook through April. Temperature expectations for South Dakota in February start with a bit of uncertainty, Edwards says.
“Currently, computer models are showing some fluctuations between colder and warmer than average for the start of the month ahead,” Edwards says. “The outlook indicates this uncertainty with equal chances of warmer, cooler or near-average temperatures for the month overall. For the three-month period of February through April, odds start to lean towards warmer than average temperatures for all but the far northwest corner of the state.”
The precipitation outlook shows February slightly more likely to have wetter than average conditions for all parts of the state but the far southern tier along the Nebraska border.
“This is still in our winter season where precipitation is historically low, so a couple of big storms could easily bring the monthly total above average. For the next three months into April, there is more uncertainty and almost all of the state is shown to have equal chances of wetter, drier or near-average precipitation.”
To get any substantial relief from drought conditions, spring precipitation will be more important than ever this year, Edwards says.
“Many areas of the state were four or more inches below average precipitation in 2020,” Edwards says. “The winter warmth is allowing for more moisture loss when it is often ‘locked’ in as frozen soils and waterways.”
As a result of the dry period from late summer through January, nearly everywhere in the state is carrying a shortage of soil moisture to start the 2021 growing season for grasses, pastures, row crops, gardens and trees. Edwards says while winter precipitation can help in improving drought conditions, it can also run off frozen ground instead of infiltrating into the soil.
In addition to a dry winter, La Niña conditions — driven by colder waters in the Pacific Ocean near the equator by South America — are in place this season. These conditions often can change the jet stream patterns over North America. For South Dakota, past La Niña winter seasons have brought colder than average temperatures, but Edwards says that has not been the case this year.
“Since 1950, there have been just four La Niña winters with warmer than average temperatures in our region, the most recent being 2011-2012,” Edwards says.
Finally, Edwards says there is another factor at play this year — the Arctic Oscillation over the northern latitudes around the North Pole.
“That has been more prominent over our region in preventing colder air from moving south into the Dakotas,” Edwards says. “Many climate forecasters see the Arctic Oscillation in its current phase weakening, and thus allowing more cold air to come into the northern U.S. states as is shown in Montana and North Dakota’s outlooks this month.”