Insect Migration Risk Forecast (IMRF)
2007 Growing Season
ACCEC (Analytical Center for Climate and Environmental Change)
Mike Sandstrom and Dave Changnon
Department of Geography
Northern Illinois University
DeKalb, IL 60115
wxtrw44@yahoo.com and dchangnon@niu.edu
Daily Forecast (updated Monday-Friday by Noon Central Time except holidays)
Forecast Release: Monday, June 25, 2007, Noon central time
Short-term (present to 48 hours):
Day 1 (Monday 6/25/2007 noon to Tuesday 6/26/2007 noon): Relative Risk of Insect migration into the Midwest: MODERATE (15-20%): Greatest risk area is east of US 83 but west of I-35, south of US 2 but north of I-90, including eastern Dakotas and western Minnesota.
Click Here For The Day 1 Risk Map (opens a new window)
Low pressure is currently located over east central Montana with a warm front northeast of the low across North Dakota into northwest Minnesota and south central Canada. A cold front is located southwest of the low through southern Montana and points to the southwest. A few showers and thunderstorms are occurring in eastern North Dakota and northwestern Minnesota. High pressure is off the Carolina coasts. Southerly winds are especially prevalent in the Plains states but do extend to the Mississippi River before they turn more southeasterly and much weaker.
Through the next 24 hours, the main insect migration focus will be across the western upper Midwest and northern Plains as the low pressure area moves to the northeast, reaching north of International Falls. Meanwhile, the cold front will also advance to the east and is expected to bisect the Dakotas. Showers and thunderstorms are expected to break out in rather high coverage right along and ahead of the front where strong southerly winds will shift rather rapidly to northerly or northwesterly winds. Given strong southerly winds currently in place across the Plains (gusts up to 40MPH) and expected precipitation coverage providing a good drop zone area, a MODERATE risk of insect migration is forecast in the eastern Dakotas and western Minnesota to account for any migratory insects currently moving in the Plains. Further east and south, the insect migration risk is lowered into the Low category due to lesser amounts and coverage of precipitation and somewhat weaker winds (especially to the east). Very low risks are extended to US 51 in Wisconsin but west of the Mississippi River south of US 20. No risk of insect migration is forecast across the eastern portions of the forecast area due to weak wind flow and lack of precipitation.
Day 2 (Tuesday 6/26/2007 noon to Wednesday 6/27/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (10-15%): Greatest risk area is southeast of a line from International Falls to Fargo to North Platte, but northwest of a line from Wichita to Columbia (Missouri) to Chicago to Alpena and Sudbury, Ontario, including Minnesota, eastern South Dakota, eastern Nebraska, much of Kansas, Iowa, northern Missouri, northwestern Illinois, Wisconsin, northern Michigan, and central Ontario south of Route 11.
Click Here For The Day 2 Risk Map (opens a new window)
Low pressure moves from International Falls to eastern Ontario or western Quebec, and the frontal boundary also moves to the southeast further into the Midwest. Showers and thunderstorms are expected to continue along and ahead of the frontal boundary, but are expected to be rather isolated or perhaps scattered, and southwesterly winds are likely to be weaker during the Day 2 period in comparison to the Day 1 period. The insect migration risk is lowered but shifted further southeast in relation to the movement of the frontal boundary, southeast of a line from International Falls to North Platte but north of a line from Wichita to Sudbury, Ontario. Very low risks are extended to the I-71 corridor to account for expected scattered precipitation and better wind flow from the south or southwest, albeit weak. No risk of insect migration is forecast across the Dakotas as they will be behind the cold front and are expected to be in northwesterly flow.
Long-term (Day 3 to Day 5: Wednesday through Saturday):
Days 3-5 (Wednesday 6/27/2007 noon to Saturday 6/30/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area on Day 3 is southeast of a line from Englehart, Ontario to Sault Ste Marie to Green Bay to Sioux City to Goodland. By Day 4, the greatest risk area is south of I-80, and by Day 5 is south of I-70.
Click Here For The Days 3-5 Risk Map (opens a new window)
Low pressure is expected to continue to move rapidly to the east, and will likely be in the northeastern United States or even over the Atlantic Ocean by Day 4 as a seasonally strong high pressure begins to build into south central Canada or the far northern Plains. The cold front is also expected to move rather quickly to the southeast, but by Days 4 and 5 is expected to become more west to east and slow in its southward movement. Southerly winds are expected to the south of the boundary, but are likely to be rather weak and precipitation is also possible across the southern United States at the end of the week in the insect source regions, and this is expected to limit insect activity and movement during this entire period. Therefore, only a Very Low risk of insect migration is forecast during the Day 3-5 period with a gradual shift southward in relation to the frontal movement. Further north, high pressure is expected to dominate the weather pattern, bringing little to no chance of precipitation and calm or unfavorable winds for insect migration in this area, so no risk is forecast for Days 4-5.
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Mike Sandstrom and Dave Changnon
Department of Geography
Northern Illinois University
DeKalb, IL 60115
E-mail: wxtrw44@yahoo.com and dchangnon@niu.edu
Temporary IMRF website: http://www.maplecity.com/~sand/cew/imrf.html
DISCLAIMER: The content in this document, and any associated figures, is strictly the opinion of the authors, and should be used for informational purposes only. The authors
assume no liability to those who may use the above content for IPM or other processes.
NOTE: This forecast, while initially developed specifically for migration of corn earworm (CEW), is applicable for all other migratory insects in the Midwest as well, such as the potato leafhopper and armyworm.
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