Moderate corn earworm migration risks remain in the forecast for the next two nights before a weather pattern change greatly reduces or virtually eliminates any risk of migration by the end of the week. Low pressure currently in Kansas should move northeast into eastern Nebraska or western Iowa by Tuesday morning. High pressure is likely to remain in Georgia or Florida, so a favorable setup for south to southwest winds to blow north and northeast from source regions in northern Texas and Louisiana will be in place tonight. Showers and storms are likely to occur to the east of the low pressure center and trailing cold front and could serve as insect drop zone regions especially from Oklahoma and Arkansas north into far eastern Kansas, Missouri, southeast Iowa, and western Illinois where a Moderate corn earworm migration risk is in place tonight and early tomorrow. Low risks extend north to near I-90 and east to I-75.
By Tuesday night and early Wednesday, the Moderate risk area shifts east as south to southwest winds along with precipitation are both expected to continue east of the cold front. The risk area lies east of a line from northwest Arkansas into north central Illinois and mainly west of I-75 from western Ohio southwest into central Kentucky and far western Tennessee. Low risks extend north to near I-94 in Michigan and east into the far eastern reaches of the corn-growing region of Ohio.
The weather pattern change begins to take hold by Wednesday night and Thursday morning as north to northwest winds become common across much of the corn-growing region except for eastern areas from I-57 east and south of I-94 where enough southwest winds remain in place around a decaying low pressure center over the western Great Lakes to warrant a Low risk. No risk is forecast thereafter as north to northwest winds lock in across the entire corn-growing region by Thursday.