A weak weather system in progressive northwest to southeast flow is expected to push into the Plains and western Midwest tonight into tomorrow. With high pressure located in the southeast United States and low pressure emerging into the northwest Plains from the northern Rockies, south to southwest winds will occur between the two pressure cells. Neither pressure cell, however, is very strong so wind flow will be rather weak and any corn earworm migration is expected to be isolated and mainly at a shorter distance. A Low corn earworm migration risk is predicted for much of Kansas, Nebraska, southern South Dakota, southwest Minnesota, western Iowa, and far western Missouri.
As the weather pattern flattens across the continental United States by the weekend, wind flow will continue to be predominantly from the west and northwest and will limit any south to north migration. As a result, no additional migration risk is predicted from Friday morning of this week into Tuesday morning of next week (May 15th).