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 6, 2007, 10:30AM central time
Short-term (present to 48 hours):
Day 1 (Friday 7/6/2007 noon to Saturday 7/7/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area is west of US 59 and south of I-94, including southern North Dakota, South Dakota, Nebraska, Kansas, far northwest Missouri, far western Iowa, and extreme western Minnesota.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has a cold frontal boundary right along the Kentucky and Tennessee state line west into extreme southern Missouri. Little in the way of precipitation is currently observed along this front. High pressure is located in North Dakota. To the north of the cold front, winds are calm or light from the north and northeast. Across the far western Plains in the western Dakotas and Nebraska, winds have returned to a southerly direction in response to the high pressure moving to the east.
During the next 24 hours, the main feature of interest will be the formation of a low pressure system over Montana. This low pressure area will cause winds to return to a southerly direction once again across the Plains as the high pressure currently in North Dakota moves to the southeast rather quickly, possibly reaching the Mississippi River valley or even further east by midday tomorrow. Despite a fairly good southerly wind and low pressure, little in the way of precipitation is expected the next 24 hours. Nonetheless, a Very Low risk of insect migration is forecast mainly west of US 59 and south of I-94 to account for the possibility of scattered or isolated migratory insects moving north from source regions in Kansas. No risk of insect migration is forecast to the east of this area due to high pressure remaining in control and unfavorable wind directions and speeds.
Day 2 (Saturday 7/7/2007 noon to Sunday 7/8/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is mainly south of US 2, east of US 83, west of I-39, and primarily north of I-90, including southeastern North Dakota, eastern South Dakota, southern and central Minnesota, and southwestern Wisconsin.
Click Here For The Day 2 Risk Map (opens a new window)
Low pressure is expected to continue to organize across the northern Plains and by the end of the period, will likely move to the east into Minnesota. High pressure will likely continue to shift quickly to the southeast, and is expected to be over the eastern United States by midday Sunday. Southwesterly winds to the south of the low pressure area and developing frontal boundary will continue to pump warm and humid conditions, and any actively migrating insects, into the Midwest from source regions in Kansas and far southern Nebraska. The frontal system may begin to turn more west to east by the end of the Day 2 forecasting period, and as waves of low pressure move along the front, scattered areas of precipitation may form, serving as potential insect drop zones right along the front. The best risk looks to be south of US 2 between US 83 and I-39, all north of I-90. Very low risks are extended south of this area west of I-55 closer to the source region. No risk of insect migration is forecast across the eastern forecast region as the lack of precipitation and duration of southerly or southwesterly winds will likely not have occurred long enough for any long distance movement of insects to this area.
Long-term (Day 3 to Day 5: Sunday through Wednesday):
Days 3-5 (Sunday 7/8/2007 noon to Wednesday 7/11/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: LOW (5-10%): Greatest risk area is mainly south of I-94 and US 10 east of the Mississippi River and along and south of I-90 west of the Mississippi River but north of I-70 east to I-57, including southern South Dakota, Nebraska, Kansas, northern Missouri, Iowa, southern Minnesota, southern Wisconsin, and northern and central Illinois. Day 4: LOW (5-10%): Greatest risk area is south of I-94 east of the Mississippi River and south of US 20 west of the Mississippi River but north of I-44 and I-70 east to I-69, including Nebraska, Kansas, northern and central Missouri, Iowa, northern and central Illinois, northern Indiana, and southern Michigan. Day 5: VERY LOW (2-5%): Greatest risk area is south of I-94 and west of I-65, including southern North Dakota, South Dakota, Nebraska, Kansas, southern and central Minnesota, Iowa, Missouri, Illinois, southern Wisconsin, and western Indiana.
Click Here For The Days 3-5 Risk Map (opens a new window)
The long term period looks to be potentially very active weather-wise across the forecasting area, with numerous opportunities for showers and thunderstorms. For insect migration risks, however, the picture is much cloudier as the positioning of weather systems and associated rainfall may complicate matters, especially in the southern part of the forecasting area in or close to insect source regions.
A west to east frontal boundary is expected to shift slowly to the south especially on Days 3 and 4, and potentially Day 5, but complicating matters is what a rather strong low pressure area moving across southern Canada will do to this frontal boundary come Tuesday and Wednesday of next week. The frontal boundary will likely serve as the focus for showers and thunderstorms and divide southerly winds from southeasterly or easterly winds, and will also be a good location for insect drop zones if any insects are able to migrate into the vicinity of the front. At this time, the best risk during the Day 3 period is roughly along and south of I-90 west of the Mississippi River and south of I-94 and US 10 to the east of the Mississippi River, with the front sinking further south on Day 4. By Day 5, the most likely scenario will be the cold front will become stationary and remain over the southern Midwest, bringing the potential for heavy rain events across the same areas that have received too much rain the past month or so, including Kansas, southern Missouri, and points south. If this happens, the low pressure moving across southern Canada will do little to provide opportunities for insect migration further north despite precipitation occurring there. Given the uncertainty in exactly how the middle of next week will actually play out, a rather broad area of Very Low risk of insect migration is forecast and we will monitor conditions throughout the weekend and provide an update in the Monday outlook. Regardless of what occurs, insect trap counts continue to remain rather low, so large movements of corn earworm and other migratory insects are not likely to occur in the next week into the Midwest.
----------------------------------------------------------------------------------------------------------
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.
-----------------------------------------------------------------------------------------------------------