Ag Weather Forum

Parched Month for Western Corn Belt

Bryce Anderson
By  Bryce Anderson , DTN Senior Ag Meteorologist
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In the Western Corn Belt, a large portion from central Iowa through north-central Missouri, along with much of Michigan, received no more than 25% of average precipitation from mid-July to mid-August. (HPRCC graphic by Nick Scalise)

For the first time since the harsh drought year of 2012, a portion of south-central Iowa was placed into Extreme Drought during the growing season. It happened in the Drought Monitor production of Aug. 15.

This is no surprise when precipitation during the prime filling period for corn and pod-setting and filling for soybeans is considered. For approximately half the state of Iowa, and south to north-central Missouri, the stretch from mid-July to mid-August featured hardly any rain; this sector of the Midwest generally had less than 50% of normal precipitation. Des Moines and Ottumwa, Iowa bear that statistic out: The Des Moines precipitation total since June 1, at just 4.67 inches, is only 40% of the normal 11.73 inches. Last year, Des Moines tallied 11.59 inches precipitation during July. Ottumwa, Iowa was even drier. Ottumwa's precipitation total since June 1, at 2.77 inches, is only 23% of normal. In the same time frame in 2016, Ottumwa logged 8.84 inches precipitation.

In addition to the dryness in Iowa and Missouri, much of southern Michigan has had similar issues with dry conditions. Most of Lower Michigan has only received 25 to 50% of normal precipitation in the key mid-July to mid-August time period. It's hard to envision crops maximizing their potential when a 30-day stretch yields so little in the way of moisture.

Dry pockets are also evident in central and southern Illinois through central Indiana and northern Ohio. However, some of these areas had very heavy, flooding rain during the spring planting time frame; so, in at least a few areas, the drier trend allowed soils to dry and crops to form stronger root systems after being challenged by a wet pattern.

Weather forecast models through the final full week of August, from Aug. 20 through Aug. 26, do suggest a promising round of showers and thunderstorms for this dry sector of the Corn Belt. One rainfall occurrence, however, will not make up the kind of precipitation deficits that have developed over a sustained time frame -- like, the entire summer period. And, one would think that the odds will be high that this upcoming offering will be closely tracked for duration, area of coverage, and actual amounts.

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