Snow is little more than a cover
MARSHALL – Calling a drought a “slow-motion” disaster, State Climatologist Greg Spoden said Monday that turning around Minnesota’s extreme drought conditions will come down to what happens in April and May.
The latest U.S. Drought Monitor has put southwest Minnesota in the extreme drought category and classified 70 percent of the state’s landscape in either extreme or severe.
And Spoden said while snowfall at this time of the year is beneficial for surface water systems like lakes and streams, it won’t do much for our corn and soybean fields.
“It might sound silly talking about a drought with a white landscape over the state, but it’s really a veneer that is covering something else that lies below the surface,” Spoden said.
What lies beneath is a dry, dusty soil profile that right now is insulated from any snowfall by frost. It won’t be until the ground thaws that that profile can be replenished. That’s why spring rains will be relished more so this year than normal.
“We’ll be very reliant on spring rains to wetten everything up again,” Spoden said. “Very little of the snow that falls this week for example, will enter the soil. In terms of agriculture, horticulture, forestry, it’s all about soil moisture, and nothing is going to change in regard to that until after the soil thaws.”
As of late autumn, the soil moisture content in the plant rooting zone was near all-time low levels at many locations, according to the State Climatology Office, and water table well levels and base flow to surface water systems will be slow to react to future precipitation.
Spoden said you have to go all the way back to the fall of 2011 to find the cause of our current conditions. That dry autumn, he said, kick-started what was to become today’s extreme drought, as it was the driest autumn in the state’s recorded history.
The dry fall was followed up with a snow-sparse winter, which preceded a warm and dry March in 2012. By the time April 1 rolled around there were already large sections of Minnesota facing a significant drought situation.
“It’s a slow-motion natural disaster,” Spoden said. “Mother Nature turned the faucet on in April and May of 2012, and that washed out some of the issues that had come into play, but only for the time.”
Spoden said farmers were able to enjoy a solid growing season last year, but were really living on borrowed moisture. By and large, he said, it was the reserve that built up from April and May rains that got producers through the 2012 growing season, even though some isolated fields around Minnesota continued to suffer.
Not helping matters was an extremely hot July, which went down as the second hottest month in Minnesota history. That heat worked to extract moisture from the landscape, and had it not been for some timely rainfall, last year’s crop wouldn’t have turned out as good as it did.
Spoden said most of southwest Minnesota saw a nine-month moisture departure of anywhere between 6 to 10 inches compared to historical averages.
“That’s a large deficit to have to make up for – you don’t have to make up for it inch-by-inch to return to some semblance of middle-of-the-road, but we will have to exceed historical averages this spring to replenish the hydrological systems that were depleted.”
Spoden said the driest swath in southern Minnesota in that nine-month window is along Minnesota Highway 60 from Mankato to Worthington.