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, July 16, 2007, 7AM central time
Short-term (present to 48 hours):
Day 1 (Monday 7/16/2007 noon to Tuesday 7/17/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is east of US 81, south of I-94, north of US 36 and I-72, and west of I-69, including far eastern Nebraska, eastern South Dakota, far northeast Kansas, southern Wisconsin, northern Illinois, northwestern Indiana, and far southwestern Michigan.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has complex of low pressure centers in the Plains and northern Rockies, with one low pressure center in far southwestern North Dakota and another in central Montana. A warm frontal boundary is located to the east and southeast of the North Dakota low right along the North Dakota and South Dakota border into central Minnesota and far west central Wisconsin. Scattered clusters of showers and thunderstorms are observed near this front, especially in Minnesota. Another cluster of storms is located over southeast Iowa in association with southerly or southeasterly winds that are found over much of the Midwest and Plains states this morning.
Throughout the next 24 hours, the low pressure areas are expected to remain in place across the western Plains and northern Rockies, as will the warm front across the upper Midwest. Southerly winds to the south of the front will feed moisture and instability further north, creating scattered areas of showers and thunderstorms along the front. A cluster of showers and storms is expected to develop in northern Iowa or southern Minnesota later today or this evening and move to the east southeast along the frontal boundary. Southerly winds into the frontal boundary from source regions in Oklahoma and southwest Kansas are not expected to be rather strong, however, so just a Low risk of insect migration is forecast mainly east of US 81 and west of I-69, south of I-94 and north of I-72 and US 36. Very Low risks are found mainly south of this area for more isolated or scattered pockets of downward moving air causing moving insects to drop out. No risk of insect migration is forecast across the far eastern forecast region and also in the far northwest and west Plains states.
Day 2 (Tuesday 7/17/2007 noon to Wednesday 7/18/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (10-15%): Greatest risk area is east of US 81, south of US 10, north of US 136, and west of I-75, including eastern South Dakota, eastern Nebraska, Iowa, far northern Illinois, southern Minnesota, southern Wisconsin, northern half of Illinois, northern Indiana, southern Michigan, and northwestern Ohio.
Click Here For The Day 2 Risk Map (opens a new window)
Low pressure is expected to begin to move to the east, and is to be likely in South Dakota or perhaps northern Nebraska by the end of the Day 2 period. The warm front will continue to the east or southeast of the low, and is expected to set up somewhere between I-90 and US 136, but its exact position will heavily depend on the strength of thunderstorms and coverage later today into tonight. The more widespread the storms tonight from Iowa east, the more the front will be pushed south, but on the other hand, the more scattered the storms, the less likely the front will move much south. For now, a middle of the road approach is best and a larger area of high end Low risk of insect migration is forecast between US 136 and US 10 mainly from the Missouri River east to the I-75 corridor, with Very Low risks surrounding the Low risk area especially to the south closer to source regions currently active in southern Missouri and points south. No risk of insect migration is forecast across the far western Plains and far upper Midwest close to the Canada border. We will watch trends closely the rest of today and tonight and have an update in tomorrow’s forecast on the best risk area.
Long-term (Day 3 to Day 5: Wednesday through Saturday):
Days 3-5 (Wednesday 7/18/2007 noon to Saturday 7/21/2007 noon): Relative Risk of Insect migration into the Midwest: Days 3-5: LOW (5-10%): Greatest risk area on Day 3 is east of US 81, south of I-94 east of the Mississippi River and south of I-90 west of the river, west of I-75, and north of I-70, including eastern Nebraska, northeast Kansas, extreme southern Minnesota, Iowa, northern Missouri, northern and central Illinois, far southern Wisconsin, southern Michigan, northern Indiana, and northwestern Ohio. On Day 4, the risk area shifts to east of I-29 and south of US 20, including much of Iowa, Missouri, Illinois, Indiana, Kentucky, and Ohio. By Day 5, the greatest area at risk is east of US 65 and south of I-80, including eastern Missouri, southeast Iowa, central and southern Illinois, Indiana, Ohio, and Kentucky.
Click Here For The Days 3-5 Risk Map (opens a new window)
The long range forecasting period is met with uncertainty as a shift in the forecast thinking has occurred throughout the weekend. While there is still some discrepancy, the general forecast trend is to shift the low pressure area expected to be in the lower Missouri River valley to the east or southeast to the Ohio River valley by the end of this forecasting period as high pressure builds into the upper Midwest. Not only would such a pattern have the opportunity to bring ample precipitation to much of the eastern Midwest later this week, insect migration risks would also possibly increase quite a bit if migratory insects are currently active in the source regions, especially across Arkansas and Missouri.
On Day 3, the warm front will likely shift at least a little further south as the low pressure continues to slowly drop to the southeast. Periodic chances for showers and thunderstorms exist along and just north of this front, and with southerly or southwesterly winds feeding into the areas of precipitation, at least a Low risk of insect migration is warranted this many days out, especially east of US 81 and south of I-90 and I-94, primarily north of I-70. No risk of insect migration continues across the far northern Plains and upper Midwest as wind flow will be unfavorable for insect migration into these areas.
By Days 4 and 5, the low pressure area is expected to continue moving east or southeast, taking the warm front and associated precipitation with it. The best risk of insect migration may actually be at the end of this forecasting period closer to active source regions in Arkansas and southern Missouri since wind speeds throughout the period are not expected to be especially strong for longer range migration further to the north. For now, a risk of insect migration is forecast mainly east of I-29 and south of I-90 on Day 4, then south of I-80 on Day 5.
Weekend corn earworm trap count trends will be analyzed closely later today and tomorrow as some increase was noted in at least northeast Arkansas and southeast Missouri late last week indicating the second generation may be on the move north now. Be sure to monitor forecasts throughout the week given weather uncertainty and positioning in addition to changes in CEW trap count trends.
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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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