Drought Effects Linger, Iowa November Rainfall Half Normal Amount

Soil moisture in Iowa won't be replenished before spring, as drought of 2012 will continue into 2013, observes state climatologist Harry Hillaker.

Published on: Dec 7, 2012

November is being described as "disappointing." It ended with only about half the normal precipitation for Iowa. Preliminary figures show the state had an average of 1.07 inches of rainfall for the month; normally Iowa receives 2.05 inches in November.

For the year to date, as of the end of November, precipitation in 2012 is at 24.74 inches for Iowa, 9.19 inches below normal for the first 11 months of the year, according to Harry Hillaker, state climatologist with the Iowa Department of Agriculture & Land Stewardship. Iowa normally receives a statewide average of about 35 inches of precipitation annually—or about 34 inches through the end of November.

A wet October had raised optimism that the drought of 2012, Iowa's worst since 1988, might be lifting. The state's October precipitation totaled 3.12 inches, or a half-inch more than normal. That was the greatest precipitation total since May and the first month with above-normal precipitation since April. "But we went back to a dry pattern in November," says Hillaker. "And with the soil due to freeze up for winter soon, that about ends much chance of replenishing soil moisture supplies before this coming spring."

DROUGHT CONTINUES: Any hope that the drought of 2012 would start to end this fall has just dried up. "We had only half as much rain as we normally get statewide in November," says Harry Hillaker state climatologist with the Iowa Department of Agriculture & Land Stewardship. He says this dry spell is mimicking the one that occurred in 1988-89.
DROUGHT CONTINUES: Any hope that the drought of 2012 would start to end this fall has just dried up. "We had only half as much rain as we normally get statewide in November," says Harry Hillaker state climatologist with the Iowa Department of Agriculture & Land Stewardship. He says this dry spell is mimicking the one that occurred in 1988-89.

Iowa didn't get the recharge it needed this fall on subsoil moisture supply
As of the end of November, two-thirds of the state's topsoil was deficient of moisture and 94% of the state's subsoil lacked adequate moisture, according to USDA's survey. Since September 1 central Iowa has received 5.97 inches of rain, which is 2.11 inches below the 8.08 inches normally received from September through November.

For months climatologists warned that the state would be in trouble if enough rain didn't come by early December, when freezing temperatures usually set in for the winter. Rainfall and snow melt on frozen ground runs off rather than soaks in. "Soil moisture levels now remain below normal statewide," notes Hillaker. "However, normal early spring rainfall across the eastern one-third of Iowa probably would put soil moisture in good shape by planting time in 2013 in that part of the state.~~~PAGE_BREAK_HERE~~~

Far northwest Iowa, however, has seen much less rainfall this fall and unfortunately even in normal times usually receives less precipitation than eastern Iowa during winter and spring. "Thus, prospects for a full profile of soil moisture by next growing season are not good in that corner of the state," says Hillaker.

The situation is similar to the major drought that gripped the state in 1988-89, when the first year brought severe heat and the second year brought water shortages. "We've missed any chance of getting a lot of recharge of soil moisture in the ground this fall," says Robert Libra, state geologist with the Iowa Department of Natural Resources. "People should be thinking about what they'll do if spring turns out to be dry."

Dry spring could mean mandatory reductions in water use by homeowners, businesses
Libra says some changes have occurred since 1988-89 that could lessen the impact of another prolonged drought. For example, many rural well owners have now connected their homes and livestock farms to rural water districts, a water source that wasn't as widely available in 1988-89 in Iowa. But rural water systems also face new challenges that weren't as severe as 25 years ago, including demands from large livestock confinement operations. "I anticipate that if it stays dry, we will have some mandatory reductions" in water use by homeowners and businesses," says Libra.

A few water utilities around Iowa, including the Des Moines Waterworks at one point, asked residents to conserve water earlier this year. Libra says his department is developing a system to track such water-conservation efforts.

How does drought of 2012 compare with 1988, the last time it was this dry?
How does the 2012 drought compare with 1988-89, which was the last time a major drought struck Iowa? At the end of November 2012, the rainfall shortage stood at 9.19 inches below normal statewide. In 1989, the statewide rainfall deficit averaged 9.8 inches at the end of November. But the year before it was even worse, with rainfall averaging 13.07 inches below normal at the end of November 1988.~~~PAGE_BREAK_HERE~~~

Hillaker says this current drought is following a pattern similar to the 1988-89 dry spell. The summer of 2012 ranked fifth-driest and 14th hottest in 140 years of records. In 1988, the rankings were somewhat reversed but still high as that summer was the fourth hottest and 14th driest.

For most of Iowa, groundwater levels are lower now than at this time last year. "Thus, it's almost a sure thing we will be starting 2013 further in the hole than we did in 2012," says Hillaker. "That means 2013 doesn't need to be as dry as 2012 for conditions to become worse than they are now."

"We are sitting on a real deficit in soil moisture," Hillaker adds. "Looking at river, stream, lake levels and water tables, 1989 is the worst year. It prolonged the dryness of 1988. And we are experiencing the same thing right now. Until you overcome the deficit in soil moisture, you aren't going to move much water to the water table." He says if Iowa has a lot of snow this winter, it may help a little. But snow only accounts for a small amount of the moisture needed. "And, moisture can't enter frozen soil," he notes.

Even if rainfall returns to normal in spring, it won't be enough to fully recharge subsoil moisture
Although we might receive a more normal amount of precipitation in 2013, the ground is still depleted. "We are now way behind where we should be on subsoil moisture," adds Hillaker. "Much of our recovery depends on the moisture we get between October and April. And we didn't get enough this fall. Looking back at last spring, because of last year's warm winter, we were already at risk at the beginning of the 2012 growing season." Soil moisture is better now everywhere in Iowa than it was at the end of the summer, but it is not as good as needed.

The U.S. drought monitor this past week reported drought conditions were about the same in Iowa as the previous week—no improvement. For weekly updates, you can follow that indicator at http://droughtmonitor.unl.edu/. Most of Iowa currently ranges from extreme to severe to moderate drought, according to the drought monitor map.

Farmers weathering 2012 are learning plenty about everything from crop insurance to seed genetics as parched conditions reshape farm business across the country. Consider our 5-part approach to moving ahead after the toughest drought since the 1930s.