Corn earworm migration risks are not expected to be a threat until the extended forecasting period and beyond as high pressure slowly slides east and southeast through the corn-growing region. High pressure most often results in calm winds and so a lack of a focused region of southerly winds precludes any migration risk through Friday morning of this week.
By the weekend, high pressure settles off to the southeast into the mid-Atlantic and southeast United States. Meanwhile, low pressure will be developing in Canada and a cold front should begin to move east southeast across the northern Plains into the upper Midwest. South to southwest winds between the pressure centers will produce at least a Low risk of corn earworm migration from Kansas and Missouri northeast into the heart of the corn-growing region in Iowa and Illinois as well as into the upper Midwest. At this time, just a Low risk is in place due to modest but non-optimal wind speeds and coverage as well as corn crops not being in a favorable stage for damage as of yet with highest silking percentages currently in the source region.