Iowa's 'flash drought' won't end as fast as it started
This year's dry spell came on much faster than year's past
Last year’s drought, the state’s worst in 50 years, crept in slowly, disguising itself at first as a welcome warm and early spring.
This year’s drought burst forth full-blown in midsummer when relentless spring storms abruptly stopped, leaving the state’s shallow-rooted crops gasping for water.
Because of its rapid onset, state climatologist Harry Hillaker and other weather professionals have been referring to the ongoing dry spell as a flash drought.
“With most droughts, rainfall events gradually get lighter and farther apart. In this case, it just suddenly stopped altogether,” Hillaker said..
Following the wettest spring on record, Iowa has recorded the seventh driest August and the 15th driest summer in 141 years.
“If you just took a snapshot right now, it would look an awful lot like last year,” said Tim Hall, bureau chief of the Department of Natural Resources Geological and Water Survey.
At the time, spring deluges looked like a reversal of last year’s drought, said Hall, who coordinated the Governor’s Drought Task Force last year.
Now it’s looking more like a brief break in a sustained drought pattern, according to Hall, who said the task force is likely to convene next week for the first time this year.
“That’s a good viewpoint,” said Brian Fuchs, a climatologist at the National Drought Mitigation Center in Lincoln, Neb., whose colleague, Mark Svoboda, coined the “flash drought” term about five years ago.
“We saw some improvement, but the vulnerability remained, masked by cool weather in the spring and early summer. It re-emerged when we started getting a perfect mix of hot, dry weather,” Fuchs said.
Most of the flash drought’s impact, so far, has been on corn and soybean crops, he said.
The lengthening dry spell has rendered moot the worries of many farmers that an early frost would prematurely end the growing season. Their desiccated corn and soybeans already have stopped growing, killed by lack of moisture.
It remains to be seen how much Iowa farmers’ yields will be reduced, but only 35 percent of the state’s corn crop and 33 percent of its soybean crop rated good to excellent in the latest U.S. Department of Agriculture crop report released Monday.
“It’s terrible,” said Wayne Humphreys, whose farm near Columbus Junction, as of Monday, had not received beneficial rainfall in six weeks.
Humphreys said some of his crops died before reaching maturity, which leads him to expect lower yields this year than during the drought of 2012.
Although some parts of Iowa have more drought damage this year than last, “this year’s crops will be better than last year’s” in the state as a whole, said Elwynn Taylor, an agriculture meteorology professor at Iowa State University.
Worst in southeast
Southeast Iowa is among the state’s driest areas, according to Hillaker.
Burlington set a record for the driest summer with just 3.86 inches of rain in the June through August period considered summer by meteorologists. Normal for Burlington in that three-month period would be 12.99 inches, Hillaker said.
Mount Pleasant, Keokuk and the Lake Rathbun dam all recorded zero precipitation in August, while Burlington and Fort Madison recorded trace amounts, he said.
Statewide, last month was the seventh-driest August in 141 years of record-keeping, with an average of 1.57 inches of rain, versus the 4.2 inches that would be normal for the month, Hillaker said.
Hillaker said rainfall averaged 3.34 inches across Iowa in July and August. Those two months were drier in only three other years — 1886, 1894 and 1947.
Hall said Iowa rivers rebounded well from the drought, reaching flood stage in several cases during the rainy spring, but many of them — including the Des Moines, Raccoon, Skunk and Iowa — “are pretty much back to where they were a year ago.”
The Iowa River was flowing at 40,000 cubic feet per second into the Coralville Lake on June 1, threatening to overtop the spillway for the third time since the dam was constructed in the late 1950s.
As of Tuesday, the Iowa River at Iowa City had a weekly average discharge of just 143 cubic feet per second, a flow that placed it in the 6th percentile, meaning that it would be flowing faster on that date in 94 out of 100 years.Hall said water utilities in western Iowa, “where hydrology makes them more vulnerable to dry conditions,” are becoming increasingly concerned about the prospects of a continuing drought.