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 18, 2007, 11AM central time
Short-term (present to 48 hours):
Day 1 (Monday 6/18/2007 noon to Tuesday 6/19/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (10-15%): Greatest risk area is east of I-29 north of I-90 and east of US 81 to the south of I-90 and mainly south of the United States and Canada border with the exception of far southwest Ontario. This risk area covers virtually the entire forecast area except the western Dakotas, western Nebraska, western Kansas, and northern Ontario.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has a low pressure area over southern Manitoba with a cold front to the south of the low along the I-29 corridor north of I-90, and southwest through central Nebraska into northeast Colorado to the south of I-90. A warm front is positioned along the Minnesota border with Ontario and then southeast through the Great Lakes into Michigan. Showers and thunderstorms are most numerous but somewhat scattered along the cold front and also a few clusters of showers and isolated thunderstorms are found over Missouri, southern Illinois, and western Kentucky. Southerly winds are found across the entire forecast area to the east of the cold front.
As the next 24 hours progresses, the low pressure in extreme south central Canada is expected to lift rather rapidly to the east or northeast into northeast Ontario or northern Quebec. Meanwhile, the cold front also slides rather quickly east from its current position through much of the Midwest, and is expected to be near the I-69 or I-65 corridor by midday tomorrow. Showers and thunderstorms are expected to be rather widespread immediately along the front with more isolated activity developing further to the east. Southerly winds are expected to be modestly strong ahead of the front from source regions primarily in Arkansas, but not as strong as the system that brought CEW and other insects such as potato leafhopper north into the Midwest approximately 10 days ago. Also, current precipitation across the southern forecast area closer to good source regions may act to inhibit insects from becoming more active and moving further north. Nonetheless, a good opportunity for insect migration north still exists so a high end Low risk of insect migration is forecast for the forecast area to the east of I-29 north of I-90 and east of US 81 to the south of I-90. The best area for migration risk appears to be closer to source regions in areas south of I-80 between US 81 and I-57 given current precipitation across this area. No risk of insect migration is forecast west of the cold front across the Dakotas, western Nebraska, and western Kansas since this area is currently experiencing westerly winds behind the front.
Day 2 (Tuesday 6/19/2007 noon to Wednesday 6/20/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is along and east of I-69 and I-65, including southeast Michigan, southwest Ontario, Ohio, eastern Indiana, and central and eastern Kentucky.
Click Here For The Day 2 Risk Map (opens a new window)
The low pressure will continue to move to the northeast, and the cold front is likely to clear the forecast area to the east of Ohio and Ontario by later in the Day 2 period. However, from midday Tuesday into Tuesday evening, a good chance of showers and thunderstorms with southerly winds is likely to exist mainly along and east of I-69 and I-65 providing the opportunity for insect dropout across the eastern Midwest and also southwestern Ontario. The source region for insects will shift to less favorable areas where insects are not quite as active as locations further west, but a Low risk of insect migration is still placed in the forecast for any unaccounted insects on the move in Tennessee and Kentucky. No risk of insect migration is forecast to the west of the front as high pressure and northwesterly or westerly winds are expected to dominate the rest of the Midwest.
Long-term (Day 3 to Day 5: Wednesday through Saturday):
Days 3-5 (Wednesday 6/20/2007 noon to Saturday 6/23/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area on Day 3 is west of I-35 north of I-80, including the Dakotas, northern Nebraska, northwest Iowa, and much of Minnesota. By Day 4, the risk area shifts further east to along and west of Lake Michigan and I-57 but is likely to remain north of I-80, including the Dakotas, northern Nebraska, Minnesota, Wisconsin, northern Iowa, and northern Illinois. On Day 5, the best risk is along and north of I-80 and I-74 but east to I-69, including the Dakotas, northern Nebraska, Minnesota, northern Iowa, Wisconsin, northern Illinois, much of Michigan, and northwest Indiana.
Click Here For The Days 3-5 Risk Map (opens a new window)
As we look out to the last half of the work week and also into the weekend, high pressure is expected to continue to slide off to the east as a new area of low pressure develops over the northern Rockies or extreme south central Canada. A warm front is likely to develop across the northern Plains and upper Midwest, providing the focus for clusters of showers and thunderstorms especially along and north of I-80, with a gradual movement to the east through time. Southerly winds are expected to return in at least a weak to moderate fashion across the Plains and Midwest especially by Day 4, providing the opportunity once again for insects to move to the north from source regions that are creeping further north as we continue to move further into the growing season. There are still some discrepancies amongst the various forecasting models concerning positioning of the low pressure and frontal systems along with precipitation coverage, so we will just forecast a Very Low risk of insect migration at this time across the Plains and upper Midwest on Days 3-5. However, as we get closer to the end of the week, the risk levels have a good chance of being increased into the Low category but with so much uncertainty at this time, a Very Low risk is more prudent to forecast versus forecasting a higher risk.
Western Bean Cutworm note: Western bean cutworm moths were captured in south central Nebraska on Friday. While this is largely a local developing pest, some indication of possible migration was noted last year in mid-July so we will continue to watch this pest and its development in the coming month to month and a half. The first catch for WBC across Nebraska is approximately a week later than last year, likely owing to cooler and wetter conditions across the Plains inhibiting development earlier this year.
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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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