Corn earworm migration risks are expected to be focused especially in the Plains and western corn-growing region for the balance of the next five days as the weather pattern remains rather stagnant and heat/humidity build north from the southern United States. South to southwest winds should be enhanced for the next couple nights especially across the Plains as high pressure in the Great Lakes region interacts with weak low pressure in the northern Rockies. As a result, Moderate corn earworm migration risks are predicted as far north as central South Dakota and southwest Minnesota later this evening into tomorrow morning before backing off and pushing a little further south into Nebraska and western Iowa and points south Thursday evening into Friday morning. Low risks extend only as far east as eastern Iowa and western Wisconsin as high pressure keeps any southerly winds from moving east.
In the extended period, as high pressure builds further north and west into the corn-growing region and heat/humidity increase, southerly winds will continue to remain focused mainly in the Plains states and will largely be driven by topographic differences from east to west and not from weather systems per se. Thus, weaker southerly winds should be in place and only Low risks are predicted.