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, July 3, 2007, 11AM central time
Short-term (present to 48 hours):
Day 1 (Tuesday 7/3/2007 noon to Wednesday 7/4/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is southeast of a line from Scottsbluff, Nebraska to Pierre, South Dakota to International Falls, Minnesota and north of I-70 and west of I-69, including eastern South Dakota, much of Nebraska, northern Kansas, northern Missouri, Iowa, much of Minnesota, Wisconsin, northern and central Illinois, northwest Indiana, and western Michigan.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has two area of low pressure over the Plains. One area is located in southern Manitoba with a secondary weaker area in far western Nebraska. A cold front is weakly connected to the two low pressure areas. Showers and thunderstorms in association with this weather system are found mostly in South Dakota with more scattered activity in Wisconsin and Michigan. High pressure is located over northern Pennsylvania. Southerly winds are especially found between the high and low pressure to the west of the Mississippi River to the frontal boundary, with more southeasterly winds across the eastern half of the forecast area.
During the next 24 hours, the low pressure areas in the Plains are expected to congeal into one main low pressure area and are forecast to move rather quickly northeast, reaching the southern tip of James Bay by the end of the forecasting period. The cold front will also slide to the southeast, but is now forecast to move just a bit slower than anticipated yesterday, so the insect migration risk has also been slowed further to the southeast. Showers and thunderstorms are expected to redevelop along the frontal boundary and continue off and on throughout the next 24 hours and likely beyond. Southerly or southwesterly winds will meet northwesterly winds at the cold front, so a good opportunity for insect drop zones exists along the front. However, insect trap counts for longer distance migratory insects are currently rather low from southern area source regions and low level winds are not optimal for migration, so just a Low risk of insect migration is forecast mainly southeast of a Scottsbluff to International Falls line but north of I-70 and northwest of I-69. Very low migration risk are forecast as far east as I-75 and also across the southern Midwest, with no risk in the far northwest Plains and also east of I-75 including Ohio, eastern Kentucky, and Ontario.
Day 2 (Wednesday 7/4/2007 noon to Thursday 7/5/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is southeast of a line from North Platte, Nebraska to Sioux City to LaCrosse to Green Bay to Sault Ste Marie and north of US 60, including eastern Nebraska, Kansas, Missouri, southeast Iowa, southern and eastern Wisconsin, Illinois, Indiana, southern Michigan, Ohio, southwestern lower Ontario, and far northern Kentucky.
Click Here For The Day 2 Risk Map (opens a new window)
The cold front is expected to continue to push off to the southeast, with precipitation continuing along its length. Southwesterly winds will occur ahead of or east of the frontal boundary, with northwesterly winds behind the front as high pressure moves in. The combination of weak southwesterly winds and low insect trap counts preclude any risks higher than Low in tomorrow’s forecast, mainly in an area southeast of a line from North Platte, Nebraska to Sault Ste Marie, Michigan and north of US 60 or the Ohio River region including far southwestern lower Ontario near Windsor. Very low risks are forecast south of US 60 to account for more scattered showers and storms in this area. Further northwest, to the north of the frontal boundary, no risk of insect migration is forecast as a weak bubble of high pressure moves in and produces light northwesterly or calm winds across the upper Midwest and northern Plains states.
Long-term (Day 3 to Day 5: Thursday through Sunday):
Days 3-5 (Thursday 7/5/2007 noon to Sunday 7/8/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: VERY LOW (2-5%): Greatest risk area is southeast of I-64 and US 60, including far southern Missouri, southern Illinois, far southern Indiana, and Kentucky. Day 4: VERY LOW (2-5%): Greatest risk area is west of I-29 and US 71 mainly south of I-94, including southern North Dakota, South Dakota, Nebraska, and Kansas. Day 5: LOW (5-10%): Greatest risk area is west of I-35 but south of I-94, including southern North Dakota, South Dakota, Nebraska, Kansas, northwest Missouri, western Iowa, and much of Minnesota.
Click Here For The Days 3-5 Risk Map (opens a new window)
On Day 3, the frontal system is expected to clear the forecast area, but not before bringing a period southwesterly or westerly winds to the far southeastern reaches of the forecast area mainly south of I-64 along with possible precipitation in the same area providing the possibility for insect drop zones. Just a Very Low risk of insect migration is forecast across this area due to less than ideal wind direction and speed, but a risk is warranted as insects that may drop out in this region may be originating from the Missouri bootheel and southern Illinois where some CEW and other migratory insects are currently active but in lower numbers. No risk is forecast elsewhere as high pressure holds on for at least one more day.
By Days 4 and 5, a new area of low pressure is expected to develop across the western Plains states or eastern Rocky Mountains, with southerly winds returning across the Plains. During Day 4, the low pressure will just be in developmental stages, so the best southerly winds and possible beginnings to insect migration risks are west of I-29 and US 71. On Day 5, the risk shifts further east to I-35 as southerly winds increase and spread east. Throughout the two days, however, precipitation is expected to be rather spotty or not occur at all across the area, but a risk is warranted due to a decent southerly wind flow across the area potentially moving any active long-distance migratory insects across the Plains states. No risk is forecast to the east of I-35 through the period due to remaining influences of high pressure and lack of precipitation.
We will continue to monitor the early week system for insect migration risks as this system currently looks like a good southerly wind producer for the Plains and possibly precipitation especially by early next week.
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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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