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: Friday, July 13, 2007, 7AM central time
Short-term (present to 48 hours):
Day 1 (Friday 7/13/2007 noon to Saturday 7/14/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area is south of I-80 east of US 83 and west of I-55, including southern Nebraska, central and eastern Kansas, southern Iowa, Missouri, and western Illinois.
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 high pressure in Virginia and also Nebraska. Winds across much of the forecasting region are from the northwest or west. Precipitation is observed over southeastern Indiana into southern Ohio, but little to no precipitation is observed anywhere else specifically in the Midwest or Great Lakes region. A large cluster of showers and thunderstorms is ongoing again this morning over Oklahoma and northwestern Texas.
Throughout the next 24 hours, the low pressure currently in Manitoba will continue to shift to the southeast, and as it does so it will also drag a cold front southeast with it. Precipitation is expected in at least a scattered fashion along the cold front, but the main question will be if any areas to the southeast of the cold front will have southerly or at least southwesterly winds to potentially move insects from source regions in Kansas, southern Missouri, or points south to the north. It appears that southwesterly winds will be best focused along and south of I-80 and west of I-55, but this area may not see the most widespread precipitation, so just a Very Low risk of insect migration is forecast for the next 24 hours. Elsewhere, no precipitation or unfavorable winds even with precipitation chances precludes any insect migration risk.
Day 2 (Saturday 7/14/2007 noon to Sunday 7/15/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk areas are: 1) east of I-35 and west of I-75 south of I-90, including eastern Iowa, far southeastern Minnesota, much of Missouri, eastern Kansas, Illinois, southern Wisconsin, Indiana, western Ohio, and western and central Kentucky; and 2) west of US 81 south of I-94, including southern North Dakota, South Dakota, Nebraska, and Kansas.
Click Here For The Day 2 Risk Map (opens a new window)
The low pressure system moving to the southeast from Canada is expected to push into the heart of the Great Lakes states during the Day 2 period. As the low pressure moves to the southeast, it is expected to push the cold front to the southeast as well. At the start of the forecast period, the front is expected to be roughly along the I-35 corridor and will likely be along the I-69 and I-65 corridors at the end of the Day 2 period as the weather pattern is rather progressive when in primarily northwest to southeast flow. Southwesterly winds are expected along and southeast of the front, along with a line of at least scattered precipitation right along the front. Due to the short duration of southwesterly winds, however, just a Very Low risk of insect migration is forecast for the Day 2 period mainly east of I-35 but west of I-75 and south of I-90.
Further west, to the west of the cold front across the upper Midwest and Plains states, high pressure will be right on the heels of the southeastward advancing cold front. By the end of the Day 2 period, the high pressure will likely be over Illinois or Indiana, so a return to southerly winds especially across the Plains is expected. Due to the lack of precipitation expected and duration of southerly winds, just a Very Low risk is forecast west of US 81 and south of I-94. No risk of insect migration is forecast across the far northern Plains and Midwest, and also over Ontario.
Long-term (Day 3 to Day 5: Sunday through Wednesday):
Days 3-5 (Sunday 7/15/2007 noon to Wednesday 7/18/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: LOW (5-10%): Greatest risk area is east of US 83 but west of the Mississippi River and south of US 2, including the eastern Dakotas, eastern and central Nebraska, eastern Kansas, central and southern Minnesota, Iowa, and Missouri. Day 4: LOW (5-10%): Greatest risk area is east of US 81 but west of I-65 and I-69 south of I-90, including far eastern Nebraska, eastern Kansas, Iowa, Missouri, southwestern Wisconsin, Illinois, and western Indiana. Day 5: LOW (5-10%): Greatest risk area is west of I-35 and south of I-94, including southern North Dakota, South Dakota, Nebraska, Kansas, southwestern Minnesota, western Iowa, and far northwestern Missouri.
Click Here For The Days 3-5 Risk Map (opens a new window)
The main focus for insect migration remains largely over the western portion of the forecast area as a rather persistent area of low pressure is expected to remain over the northern Rockies or far northwestern Plains states. With rather persistent southerly winds, the opportunity for insect migration north is possible next week.
At the start of the long-term period, low pressure is expected to begin shifting across far south central Canada into northern Minnesota. A cold front is expected to extend to the southwest of this low pressure area across the northern Plains. Ahead of the front, southerly winds are expected to continue, with the best focus west of the Mississippi River. Precipitation is possible along the front, and with an increase in southerly wind speeds, a Low risk of insect migration is forecast mainly between US 83 and the Mississippi River to the south of US 2.
By Day 4, the front is expected to shift to the southeast but how quickly it does so is still a question mark this far out and much depends on how quickly the high pressure behind the early weekend front moves off to the east. If the high pressure slows down, then the front will also likely be held further to the northwest but if the high pressure moves more quickly east, the front may make it further southeast as well. This far out, the best approach is to take a middle of the road approach and place the best insect migration risk with south winds and expected precipitation mainly between US 81 and I-69 and I-65, mainly south of I-90. Very Low risks are also placed in the forecast as far east as I-75 and also west of US 81 to account for a possible quicker movement to the east and also a new low pressure system developing over eastern Montana for areas to the west of the cold front.
On Day 5, the low pressure across eastern Montana is expected to be the main player for any insect migration risks for the Plains states. Southerly winds are expected to continue across the Plains and will likely increase in speed as the low pressure deepens. Precipitation may also occur across the Plains, so the combination of good southerly wind flow and precipitation, a Low risk is placed in the forecast west of I-35 and south of I-94. Very Low risks are also extended further east to I-71 for remnants of the cold front and associated precipitation that is expected to pass through or wash out across the Midwest and upper Midwest.
We will watch trap counts very closely over the next week and if counts start to increase in source regions across the southern Midwest, insect migration risk levels may be raised as the weather pattern is conducive to northward migration early next week.
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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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