A potent cold front is expected to push southeast through the Plains and corn-growing region the next 3-4 days. Ahead of the front, however, south to southwest winds will blow north and result in very warm to hot conditions all the way from the Plains into the upper Midwest and Great Lakes region. With at least scattered precipitation expected along and ahead of the front, there will be the opportunity for some scattered corn earworm moth flights to the north especially from source regions in Kansas. While field corn is largely past susceptible stages to insect damage in many areas, there may be some later planted fields of both field corn, sweet corn, and other vegetables especially in the upper Midwest and Great Lakes region that could see damage from new moth flights in the coming week or so.
Moderate corn earworm migration risks are predicted tonight into Thursday morning across portions of Nebraska, South/North Dakota, Minnesota, far western Wisconsin, and Iowa as southerly winds are expected to be strongest in this area. Low risks extend east to Lake Michigan and western Indiana. On Thursday night into Friday morning, the Moderate risk area shifts east as the front presses to the southeast, so the greatest risk area is located from Iowa and southeast Minnesota into Wisconsin, northern Illinois, far southwest lower Michigan, and northwest Indiana. Low risks are found as far east as Ontario and Ohio during this time. Southwest wind flow east of the cold front weakens by Friday night and Saturday morning as the parent low pressure system moves well north into Canada. Thus, only Low risks are predicted across the Great Lakes region and eastern Midwest by that time. No risk is predicted thereafter as high pressure drops south into the Plains and ushers in a pleasant and somewhat cool air mass by that time.