Drought evolved for months, could linger through August
The hot weather pattern will weaken as the days shorten and there is less radiation, says Jon Davis of Chesapeake Energy.
Published: Jul 27, 2012
The effects of the 2012 drought have been most evident the past two months.
The portion of the corn crop rated good to excellent since May 20 declined more than 70 percent in Illinois and more than 60 percent in Indiana, Missouri, and Ohio.
“There has been a lot of peak heat since (the corn crop) went through pollination in June,” Jon Davis, meteorologist with Chesapeake Energy, said last week at the Illinois Farm Bureau Commodities Conference in Normal.
Davis reported there were as many as 22 days with a maximum temperature of at least 95 degrees, between June 20 and July 23, in the Central Midwest and even more hot days in the south during that timeframe. Last week featured multiple days with high temperatures of 100-plus degrees in many portions of the state.
But, while the drought has been in the headlines for weeks, it actually started taking shape months ago.
“We had the warmest winter on record,” Davis said. “It began to set the stage for what has happened here this summer.”
The warm winter meant there was no permafrost layer in much of the Midwest, which allowed evaporation to continue all season.
The situation worsened as precipitation in the state the first half of 2012 averaged just 12.6 inches, which was the sixth-driest on record.
Meanwhile, portions of the Southwest experienced the third-driest April through June on record.
“It got extremely dry in the Rockies (earlier this year),” Davis said. “It was the start of the breeding ground of heat that’s been the drought of 2012 in the Midwest.”
Davis said elevated mixed layers (EMLs) –- hot air masses that moves in arcs –- have been funneling the extreme heat from the Southwest into the Midwest for months.
“The same mechanism was involved in the droughts of the 1930s and 1950s,” he said. “Those were set up by EMLs.”
And, unfortunately, that pattern is expected to continue through August.
“I think we’ll see more of the same in August, below-normal rainfall and above-average temperatures,” Davis said. About the only hope for relief next month is a tropical storm. But Davis doesn’t see any on the horizon.
“The tropics have been incredibly quiet,” he said. “There’s no sign of anything for the next two weeks.”
The hot weather pattern will weaken as the days shorten and there is less radiation.
“But that won’t be until September or October,” Davis added. “For early August, it doesn’t look good at all.”
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