Insect Migration Risk Forecast (IMRF)
2009 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 30, 2009 – 10:30AM Central Time
Observational Data:
Current Surface Map: The surface weather map this morning has low pressure in Quebec with a continuation of a broad north to northwest wind field from roughly the Mississippi River east to the Atlantic Ocean. High pressure is currently dominating the Mississippi River valley from Wisconsin and eastern Minnesota southward into the mid-south region. South to southeast winds are already blowing out in the Plains states to the east of developing low pressure along the Montana and Wyoming border. Little to no precipitation is currently associated with this next system but that will change later today.
Short-term Forecast (present to 48 hours):
Day 1 (Wednesday 9/30/2009 noon to Thursday 10/1/2009 noon): Relative Risk of Insect Migration: LOW (5-10%): Greatest risk area is west of US 65, north of I-80 and US 34, and south of US 12 including much of South Dakota, southwest Minnesota, western Iowa, and much of Nebraska.
Click Here For The Day 1 Risk Map (opens a new window)
Low pressure in the Rocky Mountains presses east into the Plains states by late today and into tonight. High pressure in the Mississippi River valley moves east and southeast allowing southerly wind flow to continue expanding east into the western Midwest. Given the relatively strong nature of the low pressure and the resultant pressure gradient between the low and high pressure, a good fetch of southerly winds is expected in especially the eastern Plains and western Midwest tonight into tomorrow morning. As a result, a Low risk of insect migration is predicted for areas generally west of US 65, south of US 12, and north of I-80 and US 34. Very Low risks are predicted as far north as the I-94 corridor and east to near the Mississippi River. No risk continues to the east of the river due to continued influences of high pressure and lack of wind flow in this region.
Day 2 (Thursday 10/2/2009 noon to Friday 10/2/2009 noon): Relative Risk of Insect Migration: LOW (5-10%): Greatest risk area is north of US 36, east of US 63, south of I-94 and US 18, and west of US 31 including eastern Iowa, far southern Wisconsin, northeast Missouri, northern and central Illinois, northwest Indiana, and far southwest Michigan.
Click Here For The Day 2 Risk Map (opens a new window)
A slight eastward translation to the Plains low pressure is expected during the Day 2 period with the center moving into the Missouri River valley near Sioux City, Iowa or Sioux Falls, South Dakota by Thursday night and into northern Iowa or vicinity by midday Friday. A cold front to the south of the low will also press east through the southern Midwest and lower Missouri River valley. South to southwest winds will continue especially just to the east of the front and low pressure and will be of decent strength to continue a Low risk into the Day 2 period. The highest risk area includes areas east of US 63 to US 31, south of US 18 and I-94, and generally north of US 36 or areas from eastern Iowa into Indiana and central Illinois north into southern Wisconsin. Very Low risks are predicted north to the US 10 corridor and east to near I-71 in Ohio. Despite some rather robust northwest winds on the back side of the low pressure in the Plains states, the source region for the winds is not from an active insect source region so no risk of reverse insect migration is predicted in this region.
Long-Term Forecast (Days 3 to Day 5: Friday through Monday):
Days 3-5 (Friday 10/2/2009 noon to Monday 10/5/2009 noon): Relative Risk of Insect Migration: Day 3: VERY LOW (2-5%): Greatest risk area is east of I-57 and south of US 10 to the Appalachian Mountains including far northeast Illinois, northern Indiana, northern Ohio, lower Michigan, southwest Ontario, and western New York and western Pennsylvania. Day 4: NONE Day 5: VERY LOW (2-5%): Greatest risk area is west of US 71, north of I-80, and mainly south of I-90 including southern South Dakota, southwest Minnesota, western Iowa, and Nebraska.
Click Here For The Days 3-5 Risk Map (opens a new window)
As the low pressure continues to deepen and actually decay in time, it will slowly advance into the Great Lakes region during the Day 3 to Day 4 period. The cold front to the south of the low will also press to the east. As the system weakens, south to southwest wind flow to the east of the front will also decrease in speed so just a Very Low risk of insect migration is predicted on Day 3 across a fairly broad area from I-57 east to the Appalachian Mountains and mainly south of US 10 and also into Ontario. No risk of insect migration is predicted further west due to weaker winds in this area as well.
By Day 4, the low should move into the eastern Great Lakes region and wind flow should really decrease by this time as the system loses quite a bit of strength. As a result, no focused areas of south or north winds are predicted on Day 4 so no risk of insect migration is predicted.
On Day 5, the next low pressure will already be developing along the Front Range of the Rocky Mountains and southerly winds should be present by Sunday night in at least a portion of the Plains and western Midwest. A Very Low risk of insect migration is predicted for areas mainly west of US 71 between I-80 and I-90 across especially Nebraska and South Dakota into western Iowa for this next potential weather system.
NOTE: This is the final Insect Migration Risk Forecast for the 2009 growing season.
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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
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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