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, May 18, 2007, 11:30AM Central Time
Short-term (present to 48 hours):
Day 1 (Friday 5/18/2007 noon to Saturday 5/19/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area is south of I-80 and west of US 65, including Kansas, western Missouri, southern Nebraska, and southwest Iowa.
Click Here For The Day 1 Risk Map (opens a new window)
High pressure is currently located over central Illinois while low pressure continues to organize and develop over northeastern Montana. The Mississippi River serves as a dividing line between southerly winds to the west and northerly winds to the east. A few scattered showers and storms are found on the leading edge of the southerly winds across southern Minnesota this morning.
Throughout the next 24 hours, the high pressure in Illinois will continue to drift slowly to the south, reaching near Memphis in far southwestern Tennessee by the end of this forecasting period. Low pressure will continue to develop and meander around the eastern Montana/Wyoming region. Showers and storms will be possible mainly along and north of I-90 and west of I-29 in the Dakotas later today and tonight immediately to the east of the low pressure area, possibly moving into northern Minnesota. Despite this area being in southerly winds and potential insect drop zones, no risk of insect migration is forecast due to stronger winds and a more direct path just to the south and east across areas mainly south of I-80 and west of US 65. This area has also experienced southerly winds for a longer period of time and is closer to any potential insect source regions this early in the year. Further north and east across the Great Lakes states, eastern Midwest, and Ontario, northerly winds or just a beginning to southerly winds are expected to continue, so no risk of insect migration is forecast.
Day 2 (Saturday 5/19/2007 noon to Sunday 5/20/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5%) to VERY LOW (2-5%): Greatest risk area is across Kansas and western Missouri, with slightly reduced risks of insect migration as far north as I-90 west of I-35, including Nebraska, southwestern Minnesota, and western Iowa.
Click Here For The Day 2 Risk Map (opens a new window)
High pressure forecast to be near Memphis, Tennessee at the end of the Day 1 period is forecast to continue only a slow sinking to the south, possibly reaching the I-20 corridor in Mississippi and Alabama by the end of the Day 2 forecast period. The high’s position will continue to limit more optimal southerly flow off the Gulf of Mexico, but southerly winds will continue unabated across the Plains ahead of the low pressure that will begin to deepen in eastern Wyoming. A warm front is also expected to develop roughly along the I-90 corridor, serving as a focusing mechanism for scattered thunderstorms possibly as far east as the Great Lakes states by the very end of this forecasting period and into Day 3. Once again, however, the most favored area for insect migration will be across the Plains mainly south of I-90 and west of I-35/US 65. Little in the way of forecasted precipitation in this area precludes a higher risk of insect migration at this time, but with nearly four days of southerly winds in the books by Sunday, at least a risk of insect migration exists with best chances across Kansas and Missouri. Across the eastern Midwest and into Ontario, unfavorable conditions for insect migration are expected to continue so no risk is forecast at this time.
Long-term (Days 3 to Day 5: Sunday through Tuesday):
Days 3-5 (Sunday 5/20/2007 noon to Tuesday 5/22/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: LOW (5%) to VERY LOW (2-5%): Greatest risk area is along and south of I-80 and west of I-35, but a risk exists as far north as I-94. Day 4: LOW (5%) to VERY LOW (2-5%): Greatest risk is along and south of I-90 but west of US 63 north of I-80 and west of US 65 south of I-80, with very low risks as far north as US 2. Day 5: LOW (5-8%) to VERY LOW (2-5%): Greatest risk area is across the Plains, west of I-35 and south of I-90, with Very Low risks as far north as the United States and Canada border to the west of Lake Superior and as far east as US 51 in Wisconsin and far western Illinois.
Click Here For The Days 3-5 Risk Map (opens a new window)
During the Days 3-5 forecasting period, the high pressure that is expected to be rather persistent across the southern United States for a few days is forecast to lift northeast and be positioned off the eastern United States coast by Day 5. Low pressure will continue to deepen and move slowly east into the Plains states with a cold front to its south and a warm front to the east and northeast across the upper Midwest. Southerly flow originating in northwestern Texas and Oklahoma will be found across the majority of the forecasting area by Day 5, but the best chance of insect migration will continue to be mainly along and west of the Mississippi River through the period with a risk shifting further north on a daily basis. Precipitation is expected to become more widespread by Days 4 and 5 across the northern Plains and upper Midwest, mainly north of I-80 and west of I-35.
Several days (up to 5-6 days in some areas) of persistent and occasionally gusty southerly to southwesterly winds along with moderating temperatures is a very likely possibility across portions of the Plains and portions of the Midwest by mid-week next week. If any insect source regions in northwest Texas or western Oklahoma currently contain actively flying insects, they will have numerous opportunities and time to move to the north and northeast in the next 3 to 4 days if movement is not already underway. We encourage those with interests in early-season migratory insects in the Plains and Midwest to monitor trap counts and sweep numbers over the next week for potential increases in counts.
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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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