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: Tuesday, June 19, 2007, Noon central time
Short-term (present to 48 hours):
Day 1 (Tuesday 6/19/2007 noon to Wednesday 6/20/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is east of I-69 north of I-74, and east of I-57 to the south of I-74, including southeast Michigan, southwest Ontario, eastern and southern Indiana, far southeastern Illinois, Kentucky, and Ohio.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has a low pressure area over far northern Ontario with a cold front south of the low along a line roughly from Alpena to South Bend to Saint Louis to Wichita. Showers and thunderstorms are scattered along the length of the front, primarily along and north of I-70. To the east of the front, winds continue out of the south or southwest, while immediately behind the front winds shift to the west or northwest. High pressure is currently located over central Nebraska.
During the next 24 hours, the cold front will continue to make good progress to the east, and is likely to be over the far eastern United States by midday Wednesday. However, at least during the next 12 hours or so, a risk of insect migration exists in the eastern portions of the forecast area, mainly east of I-69 north of I-74 and east of I-57 to the south of I-74 due to a continued risk of precipitation and southerly or southwesterly winds potentially pumping insects into the eastern Midwest and southwestern Ontario, Canada. The wind flow is not quite as strong as yesterday further west due to the low pressure being considerably further north today, so the risk level is lowered somewhat but still kept in the Low category.
A secondary area of concern for the Day 1 period is across western Kansas and far southwestern Nebraska. It appears that precipitation is possible across this area as southerly winds return to the west of the high pressure area that is expected to drift off to the east into Missouri and Illinois today. Due to the close proximity of this area to source regions, it would not take very much wind and scattered precipitation to at least allow a small chance of more regional insect migration, so we will forecast a Very Low risk for isolated areas of insect migration west of US 81 but south of I-80.
Day 2 (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 west of US 81 and south of I-90, including far southern South Dakota, western and central Nebraska, and western Kansas.
Click Here For The Day 2 Risk Map (opens a new window)
High pressure is likely to continue to move to the east, reaching into the eastern Midwest by midday Thursday. A new area of low pressure is likely to develop across the northern Rockies or far western Plains in Wyoming or Montana, with a warm front developing from northwest to southeast across the Plains and upper Midwest. Southerly winds are expected to return to a larger area of the Midwest in response to both the high pressure moving further east and the new area of low pressure organizing to the west. Periodic chances of mainly late afternoon into overnight clusters of thunderstorms are possible across the Plains for the next several days starting Wednesday night into Thursday along and north of the developing warm front. The exact position of this frontal boundary is still in question and its position is dictated by the movement and strength of the thunderstorm clusters that move along its length, but at least for the Day 2 period, the best risk of insect migration is forecast west of US 81 south of I-90, with Very Low risks further east to I-35 and US 65 to account for southerly winds and precipitation chances further east. The best chance for precipitation is likely along or between the I-80 and I-90 corridors, but migration risks exist further south as well on southerly winds. No risk of insect migration is forecast across the eastern Midwest, Canada, or far northern Midwest.
Long-term (Day 3 to Day 5: Thursday through Sunday):
Days 3-5 (Thursday 6/21/2007 noon to Sunday 6/24/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): On Day 3, the greatest risk area is south of I-90 east to I-57, including southern South Dakota, Nebraska, Kansas, Iowa, Missouri, and much of Illinois. On Day 4, the greatest risk area is between I-94 and I-70 east to I-75, including much of the Dakotas, Nebraska, northern Kansas, southern Minnesota, Iowa, northern Missouri, northern and central Illinois, northern Indiana, and northwestern Ohio. On Day 5, the greatest risk area is west of I-35 and US 65 including the Dakotas, western Minnesota, western Iowa, Nebraska, Kansas, and western Missouri.
Click Here For The Days 3-5 Risk Map (opens a new window)
Low pressure is expected to meander over the western Plains or northern Rockies through the period, with the northwest to southeast oriented warm front expected to persist across the Plains and Midwest at least through Days 3 and 4 before moving north at the end of the forecasting period. Southerly winds will continue along and south of the frontal boundary, and especially late day or nighttime clusters of thunderstorms will persist just along and north of the boundary. Where these thunderstorm clusters are located are the best insect drop zone areas, and currently the most likely area is south of I-90 but north of I-70 or US 36. On Day 3, the greatest risk is expected to stay west of I-57 with this area shifting east to potentially I-69 or I-75 by Day 4, but then by Day 5 the front is likely to shift to the north as low pressure is expected to really begin to develop and deepen across the Plains, increasing heat and humidity across the Plains and Midwest by late weekend into early next week. On Day 5, the best risk shifts to the west across the Plains where southerly winds are expected to be the strongest and where the best chances for precipitation are expected to exist, mainly west of I-35 north of I-80 and west of US 65 to the south of I-80. It should be noted that whenever nighttime chances of thunderstorm clusters exist across the Plains and Midwest that it is difficult to forecast the position of frontal boundaries and resultant insect drop zones one day ahead versus three or four days, so some adjustments to the forecast will likely be made as we progress through the week. In general, however, do expect another chance for more widespread insect migration starting later this week and potentially into the weekend and beyond as southerly winds really lock in across the area for a period of time.
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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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