It’s certainly great to see how far soil-moisture profiles have come across the Great Plains over the past year. Looking at the U.S. Drought Monitor, you don’t see a sea of brown and red colors that the government uses to signify severe major drought problems.
But just like that, Mother Nature can turn off the spigot, and that seems to be happening already this spring in many Plains states, as drought conditions are spreading in the southern and northern Plains, according to the most recent Drought Monitor index available.
Long term, the National Weather Service says El Niño conditions that brought some much-needed moisture to the western U.S. are weakening, and it’s becoming likely that this pattern will be replaced by a La Niña setup that would eventually bring above- to much-above normal temperatures this summer to much of the U.S.
The most common climate conditions for the southern and central Plains (Texas, Oklahoma, Kansas and Nebraska) is for warmer and drier weather during the growing season, says Nebraska State Climatologist Al Dutcher.
The highest potential for below-normal moisture would be associated with the southern Plains, he says, and La Niña conditions favor a weaker southern jet and stronger northern jet. Therefore, storm systems generally remain across the northern and north-central High Plains.
“If the La Niña conditions develop during the early summer period, drought becomes more concerning because warmer and drier condition have the potential to dominate a greater portion of the growing season,” Dutcher says. “If the La Niña event holds off until the second half of the summer, then dryness may develop during the post corn-pollination period, impacting primarily the grain fill portion of the equation.
“If it holds off until early fall, then dryness issues appear during the critical wheat-planting period. And it continues through the spring, subsoil moisture recharge is generally poor across the southern and central Plains, leading to increased drought concerns during 2017.”
Dutcher believes the strength of these events will determine, in part, how dry it gets and how elevated the drought risk becomes.
“Remember, the southern Plains has the highest probabilities of experiencing climate conditions directly tied to El Niño and La Niña signals when talking about moisture,” Dutcher says. “I fully expect that the we will experience similar conditions this spring as we did last spring for the central Plains (wet and cool) through May.”
It’s a little more difficult for the southern Plains, Dutcher notes, as this event is rapidly diminishing and may be transitioning to La Niña during May. “If so, I would be inclined to say warm and dry this summer for Oklahoma and Texas, normal to above normal the first half of the summer if El Niño is still in play through May. And, extremely hot and dry if La Niña conditions begin developing in June.”
If La Niña doesn’t develop until fall, Dutcher says he pays attention to Rocky Mountain snowpack. When he sees above-normal snowpack across the central Rockies, as shown by NRCS snowpack data released in May, he’s never seen a full blown drought across Nebraska during his 27-year career at the University of Nebraska.
“If it’s less than 80% of normal, droughts have developed every single time for the western half of Nebraska,” Dutcher says. “There’s probably some similar relationship for the southern Plains, but it may be related to different months as the snowpack melts earlier in the southern Rockies.”
I think this underscores why it’s important for those raising crops to look at their rotations and at least explore seeding cover crops, or raising some high-residue crops, to protect soils from baking and losing moisture, or losing valuable moisture to runoff.
Yes, cover crops can remove some moisture, but they will lessen evaporation and, in the long run, improve the soil’s water infiltration and water-holding capacity.
If you’re a rancher, it will certainly become more important to examine grazing practices and stocking rates if drought conditions progress. The National Drought Mitigation Center has some excellent resources on planning for droughts that ranchers might consider.