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: Wednesday, June 20, 2007, 8:45AM central time
Short-term (present to 48 hours):
Day 1 (Wednesday 6/20/2007 noon to Thursday 6/21/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is south of I-94 and north of I-70 east to I-35, including southern North Dakota, South Dakota, Nebraska, northern Kansas, southwest Minnesota, western Iowa, and far northwestern Missouri.
Click Here For The Day 1 Risk Map (opens a new window)
A look at the surface weather maps this morning reveals an area of high pressure over southeastern Iowa, with the cold front that brought scattered but locally heavy precipitation to much of the Midwest and Ontario now east of the forecast area across the Atlantic coast states. Southerly winds have returned to the far western Plains, but all precipitation that was quite heavy across Kansas last night has now moved south into Oklahoma and Texas.
As the next 24 hours progresses, the high pressure is expected to move east, bringing southerly wind flow a little further to the east by midday Thursday. A low pressure area is expected to begin to develop over eastern Wyoming, and a warm front is likely to develop east of the low pressure roughly between the I-80 and I-90 corridors east to potentially the Mississippi River. As southerly winds transport moisture northward, a cluster of showers and thunderstorms is expected to develop over South Dakota and then move to the east or southeast into Iowa before it decays late tonight. Southerly winds to the south of the front and expected precipitation are not especially strong, but given the expected and focused coverage of precipitation, a Low risk of insect migration is forecast primarily between I-94 and I-70 to the west of I-35. Very low risks are extended further east to US 53 and the Mississippi River, and also south of the Low risk area closer to active insect source regions. No risk of insect migration is forecast across the eastern Midwest and Ontario where high pressure will remain in control of the weather and provide unfavorable insect migration risks.
Day 2 (Thursday 6/21/2007 noon to Friday 6/22/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is between I-90 and I-70 east to I-57, including far southern South Dakota, Nebraska, northern Kansas, extreme southern Minnesota, Iowa, northern Missouri, and northern and central Illinois.
Click Here For The Day 2 Risk Map (opens a new window)
Low pressure is expected to continue to develop over the northern Rockies or far western Plains states, with the warm front continuing to hold residence through the Plains and Midwest. The exact position of the front is key for not only the precipitation forecast but also the resultant insect migration risk, as each organized cluster of thunderstorms will have an influence on the location of the front. At this time, however, the front is expected to be pushed or reinforced further to the south, roughly near the I-80 corridor or just south. A new thunderstorm cluster or several clusters are expected to develop most likely over eastern Nebraska or Iowa later in the day or during the evening hours Thursday, and then spread east. Southerly winds will continue to feed into the area, but again are not expected to be overly strong, so just a Low risk of insect migration is forecast mainly between I-90 and I-70 west of I-57. Very Low risks surround the Low risk area as far north as I-94, as far east as I-75, and to the southern edge of the forecast area to account for more scattered precipitation or localized movement of insects, especially in the southern forecast region.
Long-term (Day 3 to Day 5: Friday through Monday):
Days 3-5 (Friday 6/22/2007 noon to Monday 6/25/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area on Day 3 is east of US 83 south of US 20 and north of US 60 west of I-75, including southern Nebraska, Kansas, much of Iowa, Missouri, Illinois, and Indiana. By Day 4 and 5, the greatest risk area is north of I-90 and west of Lake Michigan, including the Dakotas, Minnesota, northern and central Wisconsin, and the UP of Michigan.
Click Here For The Days 3-5 Risk Map (opens a new window)
The theme of the 3-5 day forecast period will be the persistent area of low pressure across the northwestern Plains and building heat across especially the Plains and Midwest states. The low pressure is likely to deepen enough to cause the warm front to move rapidly north by early in the weekend, and take its associated precipitation risk with it. On Day 3, however, a cluster of thunderstorms is likely to occur across the southern Midwest, mainly south of US 20 and east of US 83, so a Low risk of insect migration is forecast to account for southerly winds feeding into this precipitation area. The exact position of this cluster of storms will likely not be known until Friday, but will likely focus along the US 136 corridor. By both Day 4 and Day 5, the front is expected to move north as heat and humidity builds into the Plains, and a pattern known as a “ring of fire” takes hold across the Plains and Midwest. What this pattern means is rather persistent heat and humidity act to suppress any precipitation to the south of the warm front, but areas north of the warm front are at a daily or nightly risk of thunderstorms over the same areas. The warm front is likely to be positioned along or north of I-90 on Days 4 and 5 and likely beyond into early next week. Therefore, a Low risk of insect migration is forecast north of I-90 but west of Lake Michigan to take into account the risk of weak to moderately strong southerly winds potentially moving insects north into the far upper Midwest. While risks of insect migration exist to the south of the Low risk area by Days 4 and 5, the effect of building heat may impact insect activity so just a Very Low risk of insect migration is forecast mainly west of I-65. There is still uncertainty in the position of the frontal boundaries during this period, so we will continue to monitor conditions and provide updates as necessary in tomorrow and Friday’s forecast issuance.
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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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