The Yankton region could see continued drought through at least April, according to a U.S. Department of Agriculture climatologist.
Dennis Todey told the Press & Dakotan on Thursday that southeast South Dakota and northeast Nebraska may see prolonged drought, which could create problems for agriculture.
“The Yankton area is one that is more concerning given overall dryness carrying over from last year,” the former South Dakota state climatologist said. “There is still time for things to improve this year, but we need that to happen.”
Todey, director of the USDA Midwest Climate Hub, joined others on a monthly multi-state webinar. The presenters looked back at 2020 and looked ahead to the conditions in the coming months.
This week’s U.S. Drought Monitor report showed Yankton and the surrounding area in severe drought. Areas just to the west were in moderate drought, while areas to the east were listed in extreme drought.
During Thursday’s webinar, Illinois state climatologist Trent Ford saw more of the same for the Central Plains: warmer and drier than average.
“The expectation is that this will exist for at least through the end of winter if not into spring,” he said.
Because of the persistent drought, the plains have experienced a soil moisture deficit, Ford said. In addition, the region has seen increased soil evaporation.
The seven-day forecast calls for 0.25-0.5 inch of precipitation through the Central Plains, Ford said. Looking ahead, the outlook calls for warm and dry conditions through May, especially for the Dakotas and Nebraska.
Todey isn’t ready to compare the current situation to the drought year of 2012. However, he said the region badly needs precipitation right now.
“I would say, if you’re in very dry soil now, I would be at some level of increased concern,” he said. “If you’re in an area or a place where irrigation is available, it’s probably not as much concern in serious drought conditions as it would be if you’re in the drylands.”
The plains have seen a dramatic turnaround in conditions during the past year, Ford noted. In Sioux Falls, 2018 was the second wettest year and 2019 was the wettest year on record, while 2020 was the sixth driest.
“We went from 2019, which had flooding all the time, and now we have drought. That’s how dry 2020 was (in comparison) and how much water has been lost out of these soils,” Ford said.
“We lost 10-15 inches of water in the last year, with 45% of the entire area in moderate drought or worse. Parts of Nebraska are still dealing with severe to extreme and even exceptional drought.”
Winter generally brings a smaller amount of moisture to the Central Plains, Ford said.
“When you get west of the Mississippi River, the expectation for replenishing those depleted soils in January and February are less and less,” he said. “You don’t typically see abundant rainfall to replenish these soils. Some (precipitation) has stuck around from last year’s growing season.”
A La Nina weather pattern may arrive from the Pacific Ocean during late winter and early spring, Ford said. The La Nina could bring wetter conditions for the Central Plains, particularly in the west, during February-April. The long-range forecast calls for another potential La Nina re-emergence in August-October.
“It’s not unusual to have a double dip of La Nina, but the second one is usually weaker,” said Doug Kluck, the NOAA Central Region Climate Services Director in Kansas City.
HOW DID WE GET HERE?
The current warm, dry conditions represent the latest of a similar trend through the past year, Ford said. During 2020, every state in the Lower 48 showed warmer-than-average temperatures and was the fifth-warmest year on record.
Both minimum and maximum daily temperatures were above average, but the warmer “low” mercury readings were the most noticeable, he said.
“Parts of the Dakotas and Montana have departed 10 to 15 degrees above normal for temperature. Every part of the region has been above normal for the last 90 days,” he said. “Some temperature differences across the Northern Plains are eye popping. It’s been very warm so far, with winter temperatures up this season.”
The warm temperatures continued from summer and early fall into November and December, Ford said. During the last 60 days, most of the Central Plains has been 1-4 inches drier than normal. The northern plains, from South Dakota to Montana, have seen less than 10% of normal.
“Even though it’s less than 10% of normal, which can look pretty ominous, this is chronologically a pretty dry time of year,” he said. “In areas of South Dakota, the 10% of normal during the last 60 days comes to only about 1 inch, or less than that.”
Now is generally not the time to catch up on precipitation, Ford said.
“If you’re trying to make up soil moisture deficits because of drought, this isn’t normally the time to do it,” he said.
As a result of the warmer and drier weather, the region has seen reduced snowpack and a rise in soil temperatures, Ford said. Not much of the soil four inches under sod measured below freezing, and frost depths ranged from less than 3 inches to 6-12 inches.
“Not having deep soil frost allows for higher penetration and infiltration,” he said. “With higher snowfall and rainfall, it helps replenish the moisture. But in this region, we wouldn’t expect it this time of year.”
Much of South Dakota and Nebraska have remained snow-free, with very little water in any plains snowpack.
Much of the Northern Hemisphere has remained warmer than normal, Kluck said. “We’re not tapping the Arctic air. We’re getting the Pacific air masses in here, and the cold is trapped up north,” he said.
Todey noted that not even extreme northern regions are showing normal cold temperatures.
“The lack of cold must have some connection to a lack of ice over the (North) Pole,” he said. “We’re seeing shrinking in the polar ice coverage, so there has to be some relationship with the lack of overall cold (weather) there, too.”
Looking ahead, Todey noted that very dry soil conditions should limit flooding problems, whereas the 2019 flooding arose from major rainfall on top of snow and frozen ground.
However, a presenter noted flooding could still occur in the tributaries dumping into the major rivers.
The first step toward receiving needed moisture may arrive this weekend.
The forecast through Monday calls for mostly cloudy skies, lows in the single digits and teens, highs in the teens and 20s, and a chance of snow late Friday night through Saturday night.
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