As Tropical Storm Isaac moves up the Mississippi River Valley with drenching rain, it will probably miss the drought-parched areas of the Midwest that need water most while ruining crops in other areas waiting for harvest.
Flood warnings and watches reach across Louisiana, which may get up to 20 inches (51 centimeters) of rain, and through Arkansas, where as much as 5 inches may fall, according to the National Weather Service. After Isaac begins to break up, its remnants are expected to drift north into Missouri and then east across Illinois and Indiana.
“It may put a dent in it, but it isn’t going to relieve” the drought, said Jeff Masters, co-founder of Weather Underground in Ann Arbor, Michigan. “It may knock them down one category.”
Drought gripped 63.2 percent of the contiguous 48 states as of Aug. 21, according to the U.S. Drought Monitor in Lincoln, Nebraska. Of the four official categories of drought, the two worst covered 23.01 percent of the 48 states.
The dryness has left 38 percent of U.S. soybeans in poor or very poor condition, while 52 percent of corn was rated in the worst categories, the Department of Agriculture said.
Terry Hayhurst, who farms in Vigo County, Indiana, 11 miles south of Terre Haute, spent most of this summer looking up at the sky, hoping for rain.
Now that Isaac is predicted to bring soaking showers to his 1,200 acres of corn, soybeans and sorghum-sudangrass, Hayhurst said the rain will mostly just delay the harvest of corn and feed for his cows.
“For the most part” the rain is coming too late, Hayhurst said in an interview. “But we’ll take moisture this year, however we can get it.”
The soybeans, which he feared could be a total loss a month ago, could benefit from a deluge.
“Of course, we don’t want to get 20 inches,” he said.
For the rain to do the most good, it needs to fall slowly and over a few days, said David Miskus, a meteorologist with the U.S. Climate Prediction Center in Camp Springs, Maryland. If the rain falls hard and fast, most of it will run off and won’t be absorbed by the soil.
“It’s definitely too late to help corn, and I am not sure about soybeans, but we can definitely use the moisture no matter what,” said Miskus, also an author of the U.S. Drought Monitor, which will be updated tomorrow. “A slow, steady rain would be nice for several days.”
The lack of rain across the Midwest has also caused the shipping channel in the Mississippi River to shrink to where less freight can be carried by barges on the nation’s largest waterway and its tributaries, including the Ohio River.
More than 566 million tons of freight valued at $180 billion moved through inland waterways in 2010, including 60 percent of U.S. grain exports, 22 percent of domestic petroleum and 20 percent of the coal used to generate electricity, said the National Waterways Foundation in Arlington, Virginia.
At 2 p.m. local time, Isaac was about 50 miles (80 kilometers) west-southwest of New Orleans with top winds of 70 miles per hour, 4 mph below hurricane strength.
As Isaac moves north, the amount of rain it brings will fall, said Dan Pydynowski, a meteorologist with AccuWeather Inc. in State College, Pennsylvania. When Isaac leaves Arkansas, it’s forecast to drop 1 to 2 inches in Springfield, Missouri.
The heavy rain expected in Mississippi, Arkansas and Louisiana may be more hindrance than help to farmers, said Joel Widenor, co-founder of Commodity Weather Group LLC in Bethesda, Maryland. Beans, rice and cotton have yet to be harvested.
The rain can hurt the quality of cotton and gusty winds can knock the bolls off the plant, he said.
“If it actually falls off, it may just be a total loss,” Widenor said by telephone.
The rain in Louisiana also won’t affect the Mississippi River because there aren’t any large tributaries in the area to capture the flow, said Jeff Graschel, a service coordination hydrologist at the Lower Mississippi River Forecast Center in Slidell, Louisiana.
“All this rain that we are getting here falls into the Gulf of Mexico,” Graschel said.
Heavy rain draining into the Ohio River is needed to help shippers on the Mississippi. Graschel said that isn’t likely to happen.
“It really does appear it will be a short-term situation and not helping us in the long term,” Graschel said.