Iowa is among many states in the region that are seeing snowfall well below normal this winter, and the lack of snowpack out west is bringing a below-normal runoff forecast for the Missouri River Basin.
Ryan Larsen, with the U.S. Army Corps of Engineers, says with below-normal mountain snowpack and little-to-no plains snowpack, any runoff over the next several months will depend on rainfall.
“The Climate Prediction Center’s March precipitation outlook is showing increased chances for above-normal precipitation across eastern portions of the upper basin,” Larsen says. “However, that area of the upper basin also corresponds to dry soil conditions that have increased in dryness over the last month. In general, dry soil conditions mean more precipitation is required for runoff to occur.”
February runoff in the Missouri River Basin above Sioux City was 113% of average due to the warm month, but the runoff forecast remains at 80% of average.
Doug Kluck, a climatologist with the National Drought Mitigation Center, says the lack of mountain snowpack comes despite average to above-average precipitation in the mountainous areas of the basin.
“We have seen precipitation and it’s close to normal since October 1st, but guess what? It’s not falling as snow. It has fallen as rain in many of these places, so it runs off right away,” Kluck says. “We don’t have the, if you will, reservoir of snowpack to rely on later in the melt season.” Kluck says little-to-no snowpack has accumulated on the plains.
Lisa Holts, a hydrologist with the National Weather Service, says drought conditions are expanding, with more than 57% of the basin now experiencing at least moderate drought conditions. Holts says western portions of the basin are facing the harshest drought conditions.
“We cannot ignore that the basin is continuing to get drier,” Holts says. “Drought has expanded across the basin since the start of the calendar year and beginning to approach drought coverage similar to this time last year.”
Kluck says rain has been in the forecast for Iowa and many surrounding states, but the driest areas further west and in the plains were only expecting up to a half-inch.
“Honestly, that’s not a lot to write home about in the plains. The mountains will be getting some snows, so that’s good,” Kluck says. “I’m not sure how substantial that’s going to be in terms of heavy snows and such, but I guess anything is good at this point. It is turning into spring, so we expect spring rains to start coming.”
Releases from Gavins Point Dam in Yankton, South Dakota, will soon be increased to begin providing minimum service navigation flow support on the lower Missouri River.
(By Ethan Hewett, KMA, Shenandoah)