Insect Migration Risk Forecast (IMRF)
2008 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, September 17, 2008 – 10AM Central Time
Short-term (present to 48 hours):
Day 1 (Wednesday 9/17/2008 noon to Thursday 9/18/2008 noon): Relative Risk of Insect Migration: NONE
Click Here For The Day 1 Risk Map (opens a new window)
CURRENT WEATHER: The surface weather map this morning has high pressure stretched from southeast Missouri to along the Ohio River valley northeast into the New England states. A very weak cold front is also observed from the northern Great Lakes westward along I-90 into South Dakota. Winds to the south of this front are light southerly or southwesterly, with a subtle wind shift north of the boundary to the northeast and east. Little to no precipitation is observed in the forecast region this morning.
RECENT CEW TRAP COUNT OBSERVATIONS: For the latest trap counts, please visit http://www.pestwatch.psu.edu
The cold front is expected to wash out during the next 24 hours as low pressure develops in Montana or southern Canada. High pressure is predicted to move very little to the east, so any southerly flow in association with the cold front will remain in the far western Plains where insect migration is of little to no concern this time of year. Thus, no risk of insect migration is forecast due to calm or light northerly winds elsewhere.
Day 2 (Thursday 9/18/2008 noon to Friday 9/19/2008 noon): Relative Risk of Insect Migration: VERY LOW (2-5%): Greatest risk area is west of the Mississippi River and US 53 to the south of US 12 including eastern South Dakota, eastern Nebraska, southern and central Minnesota, southwest Wisconsin, and much of Iowa.
Click Here For The Day 2 Risk Map (opens a new window)
The developing low pressure moves east northeast into southern Canada during the Day 2 period, reaching the Manitoba and Ontario vicinity by midday Friday. A trailing cold front to the southwest of the front will snake its way into the far western Plains. As high pressure in the Mississippi River valley advances to the east, southerly to southwesterly winds will have the opportunity to expand to the east across the Plains, western Corn Belt, and upper Midwest. Overall wind speeds, however, are not expected to be overly strong and plus with the time of the growing season it is, just a Very Low risk of insect migration is forecast essentially from the Mississippi River and US 53 westward, all south of US 12. Further east, with high pressure remaining in control, no risk of insect migration is forecast due to light or unfavorable winds.
Long-term (Days 3 to Day 5: Friday through Monday):
Days 3-5 (Friday 9/19/2008 noon to Monday 9/22/2008 noon): Relative Risk of Insect Migration: Days 3-4: NONE Day 5: VERY LOW (2-5%): Greatest risk area is west of I-35 and south of US 12 including eastern South Dakota, southwest Minnesota, western Iowa, and eastern Nebraska.
Click Here For The Days 3-5 Risk Map (opens a new window)
On Day 3, the main low pressure area moves northeast into the James Bay region with the cold front south of the low really decreasing in strength as it presses northeast across the upper Midwest. Southerly winds, as a result, really decrease as well and become less and less defined with time. Thus, no risk of insect migration is forecast on Day 3 due to a lack of good southerly flow and especially precipitation to serve as a drop zone for any migrating insects.
By Day 4, the next low pressure develops in Montana and southern Canada almost in the exact location as the previous low. Again, like the next 24 hours, any southerly winds will be confined to the far western Plains so no risk of insect migration is forecast as conditions will be unfavorable for either south to north or north to south migration.
Looking ahead to Day 5, low pressure begins advancing to the east into extreme south central Canada or the far northern Plains in North Dakota. Southerly winds will expand east as a weak area of high pressure moves eastward into the southwest Great Lakes region. The result will be an increase in southerly winds especially to the west of I-35 and south of US 12 where a Very Low risk of insect migration is forecast. This system will be monitored closely given the potential longer duration of southerly winds next week that could spread some migratory insects into especially the upper Midwest.
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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
Homepage: http://agweather.niu.edu, temporary site 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, black cutworm, and armyworm.
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