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: Monday, May 21, 2007, 8AM Central Time
Short-term (present to 48 hours):
Day 1 (Monday 5/21/2007 noon to Tuesday 5/22/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is along and south of I-94 between US 83 and I-39/I-55, including the eastern Dakotas, Nebraska, Kansas, Missouri, Iowa, southern Minnesota, western Wisconsin, and western Illinois. Very Low risks extend as far east as I-65 and Lake Michigan.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather maps this morning show a low pressure area over the far western Dakotas with a cold front to its south along the Nebraska/Wyoming border into northeastern Colorado. High pressure continues to hold firm over the southeastern United States. Between the high and low pressure, southerly winds are found up to about I-90 where a warm front is observed. Scattered precipitation is common up and down the Plains ahead of the cold front, and also to the north of the warm front in a much more scattered fashion from the Mississippi River west.
The rather strong low pressure system is expected to remain rather stationary or move a little bit to the northeast, remaining in the western Dakotas and far western Nebraska through this forecasting period. High pressure is expected to drift off to the east and be largely east of the forecast region, bringing southerly winds to all of the Midwest and most of Ontario with the exception of far, far northwestern South Dakota and North Dakota where the front will have already passed. Increased risk percentages are now forecast along and south of I-94 across much of the Midwest, as far east as I-39 and I-55 and along and east of the cold front east of US 83 for Day 1. The greatest southerly winds will be focused in this area, thus the higher risks, but a Very Low risk will also exist as far east as I-65, Lake Michigan, and far southwestern upper Ontario north of Lake Superior where southerly winds will also be present. These areas were also under the influence of cooler temperatures and easterly winds for most of the day Sunday, so lower risks are forecast in this area given the shorter duration of southerly winds. Precipitation will be likely along the front across the far northwestern Midwest in the Dakotas, Nebraska, and northwest Minnesota, quite a distance from insect source regions so higher risk percentages are not forecast at this time.
Day 2 (Tuesday 5/22/2007 noon to Wednesday 5/23/2007 noon): Relative Risk of Insect migration into the Midwest: LOW (5-10%): Greatest risk area is along and south of I-94 between US 83 and I-57, including the eastern Dakotas, eastern Nebraska, eastern Kansas, southern Minnesota, Iowa, Missouri, Wisconsin, and much of Illinois. Very Low risks are forecast east of this area to I-75.
Click Here For The Day 2 Risk Map (opens a new window)
The low pressure forecast to be over the Dakotas at the end of the Day 1 period is expected to begin moving to the northeast, reaching to near International Falls in extreme northern Minnesota by the end of the Day 2 forecast period. The cold front will also move east, reaching roughly along the US 83 corridor. Precipitation will be focused along and just ahead of the front, with southerly winds strongest primarily from just east of the Mississippi River to east of the cold front, so the highest insect migration risk is forecast west of I-57 and Lake Michigan to the cold front. Very low but still notable risks of insect migration are forecast as far east as I-75. The far western Plains will have no risk of insect migration due to northerly winds along and west of US 83. The source region for southerly winds will likely be focused a little further east in Oklahoma and western Arkansas, very close or in areas where corn earworm (CEW) are currently reported to be active and flying.
Long-term (Days 3 to Day 5: Wednesday through Friday):
Days 3-5 (Wednesday 5/23/2007 noon to Friday 5/25/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: LOW (5-8%): Greatest risk is from US 81 to I-65 but largely south of US 12, including the far eastern Dakotas, eastern Nebraska, eastern Kansas, Missouri, Iowa, southern Minnesota, Wisconsin, Illinois, and western Indiana. Day 4: VERY LOW (2-5%): Greatest risk is from I-35 corridor to eastern edge of forecast area, covering areas east of a line from Duluth to Des Moines to Wichita. Day 5: VERY LOW (2-5%): Two areas: First area is along and east of I-55, covering all areas east of a line from Lake Superior to Madison to Springfield, Illinois, to Saint Louis, Missouri. The second area is along and south of I-90 and west of I-35, including much of Kansas, Nebraska, and southwestern Iowa.
Click Here For The Days 3-5 Risk Map (opens a new window)
The area of low pressure will begin to slow as it ages and dissipates over southern upper Ontario through the end of the work week. The cold front, however, will continue to advance to the east but will also begin to lose some punch with time. Southerly winds, however, will continue ahead of the front, so Low risks of insect migration are forecast on Day 3 as far east as I-65 and ahead of the cold front. By Days 4 and 5, the strength of southerly winds and the cold front are expected to continue to decrease, so the forecast risk of insect migration is also lessened to the Very Low category but will extend to all areas east of the I-35 corridor on Day 4 and east of I-55 by Day 5 including southeastern Ontario to the east of Lake Huron.
As the first low pressure and associated cold front move largely out of the Midwest by the end of the week, a new area of low pressure is expected to already begin developing as soon as Day 4 across northeastern Colorado or eastern Wyoming, and by Day 5 is expected to commence southerly flow in earnest across the far western Plains (mainly south of I-90) with an attendant threat of precipitation along a developing warm front in this region. At this time, a Very Low risk of insect migration is forecast along and south of I-90 and west of I-35 for the Day 5 time period, but the timing is still in question since the current system may act to slow the late-week system down, and the strength is also still suspect. Enough confidence exists, however, to at least place an insect migration risk in the forecast for Day 5 across the western Plains and wait for future details as the week progresses concerning this new, potentially active system for the central United States by next weekend.
-----------------------------------------------------------------------------------------------------------
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.
-----------------------------------------------------------------------------------------------------------