AccuWeather.com

By Alex Sosnowski, Expert Senior Meteorologist

Aug 9, 2010; 11:00 AM ET

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Despite excessive rain falling on Iowa and other corn areas in the Midwest, it may come down to the weather around harvest time to ensure a quality crop and boost for consumers' wallets.

Judging by the amount of rain falling on corn in Iowa and neighboring states this summer, it would seem the region is turning into a tropical rain forest.

While that comment is surely an exaggeration, there are many places in Iowa, Nebraska, Illinois, Wisconsin and other nearby states that have received over twice their normal rainfall since June 1.

Some residents in the region have had their sleep and daily activities disrupted by thunderstorms and downpours.

This radar estimate of total rainfall for the 24-hour period ending at 9:00 a.m. CDT Monday, August 9, 2010, indicates up to 6 inches of rain (red areas) has fallen on parts of Iowa and Wisconsin.

Both AccuWeather.com short-term and long-range forecasts indicate that more of the same may be in store for the region as summer shifts into autumn.

Nearly every day this summer, a cluster of showers and thunderstorms has been moving into or moving out of Iowa, depositing heavy rain in the process.

A number of locations in Iowa, including: Newton, Des Moines, Ottumwa, Dubuque and Ames have received between 20 and 24 inches of rain this summer.

Rainfall of one and a half to twice that of normal, or 16 to 20 inches, has also extended into Kirksville, Mo., Wausau, Wis., Norfolk, Neb., Shelbyville, Ind. and Chicago, Ill. since early June.

Rain of this magnitude has led to river flooding in some communities, repeatedly inundating fields.

In areas where there has been little or no flooding, the corn seems healthy, with some of our Facebook fans noting the stalks are taller than "Frankenstein."

In other areas, there are reports of stalks turning yellow and some stalks have little or no ears on them.

According to the U.S.D.A. about 70 percent of the Iowa corn crop is rated at good to excellent as of early August.

So it would appear, so far, the rain has helped, rather than hurt the corn crop in most of the region.

Throughout the area that has received excessive rain, temperatures have averaged between 2 and 4 degrees higher than usual this summer.

No doubt, unusual warmth accompanying the excessive rainfall has been assisting by raising evaporation rates and allowing vigorous growth of the crop.

However, as we approach harvest time in the fall, ongoing wet weather could greatly negatively affect production. Much of the corn grown in this region is for grain purposes.

According to AccuWeather.com Agricultural Meteorologist, Dale Mohler, "A lack of rain is needed during the autumn to allow the kernels to properly dry prior to harvest."

AccuWeather.com meteorologists expect the excessive rainfall to continue much of this week. It is possible some areas, centered on Iowa once again, may receive an additional half a foot of rain over the next 5 to 7 days.

Continuing persistent, heavy rain may lead to more cases of plant and kernel rot. "Rain and damp conditions around harvest time can negatively affect the quality of the kernels," Mohler added.

In the fall, as temperatures trend downward, evaporation rates plummet, hence the need for significantly less rain as harvest time approaches in late September through early November.

Corn used as grain is harvested in the fall, like this. (Photos.com)

AccuWeather.com long-range forecaster Joe Bastardi and others expect above-normal rainfall and above-normal temperatures to continue well into the fall over a significant part of the central Plains and part of the Midwest, where a great deal of the corn crop is located. However, the departures may be less extreme than that experienced during this summer.

Modern, U.S. agriculture is amazingly resilient and has weathered may problems from Mother Nature in recent years.

While a bumper crop is still expected, the weather will have to cooperate in the end to ensure a "quality" corn crop come October to avoid paying potentially higher feed and grain-related prices.

Interestingly, not too far south and east of the heavy rain area, a lack of rain, combined with excessive ongoing heat is taking its toll on ground moisture.

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