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: Thursday, July 5, 2007, Noon central time
Short-term (present to 48 hours):
Day 1 (Thursday 7/5/2007 noon to Friday 7/6/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area is east of I-69 and south of I-70 and I-44, including far southern Missouri, southern Illinois, Kentucky, southeastern Indiana, and Ohio.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has a cold front stretched through Ontario southward to Detroit and then to St Louis and southwest to Tulsa, Oklahoma. To the southeast of the front, southwesterly or southerly winds prevail, while behind the front, winds are mostly from the north or northwest. Showers and thunderstorms are especially common in Kentucky and Ohio with more scattered activity along the frontal boundary. High pressure is located in far northeast Montana and is building southeast.
For the next 24 hours, the main concern for any possible insect migration is across the far southeastern portion of the forecast area, mainly south of the Indiana Toll Road and Ohio Turnpike and east of I-69 and also south of I-70 and I-44. The cold front will continue to shift to the southeast, but will not clear the forecasting region until later tonight or sometime tomorrow. With southerly or southwesterly winds and a continued chance for scattered to possibly higher coverage showers and thunderstorms providing the opportunities for insect drop zones, a Very Low risk of insect migration is forecast. The forecast level, however, is kept rather low due to low trap counts in or close to the source regions in southwest Kentucky, the Missouri bootheel, and western Tennessee. If anything does migrate north, catches further northeast will likely be very low and only on a random basis. No risk of insect migration is forecast across the Plains or Midwest as high pressure will build into the region providing an unfavorable pattern for insect migration.
Day 2 (Friday 7/6/2007 noon to Saturday 7/7/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area is west of US 81 and south of I-94, including far southern North Dakota, South Dakota, Nebraska, and Kansas.
Click Here For The Day 2 Risk Map (opens a new window)
The cold front is expected to push far enough to the east or southeast to pose little to no threat of insect migration across areas currently in a risk area today. High pressure is expected to continue to build into the Plains and upper Midwest, producing a combination of calm or light northerly winds and no precipitation.
As the high pressure moves further to the east into the Mississippi River valley, a new low pressure area will likely develop over the northern Rockies in Montana or far southern Alberta or Saskatchewan, and this will result in a return of southerly winds across the far western Plains. Due to the lack of forecasted precipitation in the western Plains states, just a Very Low risk of insect migration is forecast mainly west of US 81 and south of I-94 for the possibility of any rogue insects moving north from source regions in southwest or western Kansas. Further north and east, no risk of insect migration is forecast as the area will be under the influence of high pressure and unfavorable long-distance insect migration chances.
Long-term (Day 3 to Day 5: Saturday through Tuesday):
Days 3-5 (Saturday 7/7/2007 noon to Tuesday 7/10/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: VERY LOW (2-5%): Greatest risk area is west of I-35 and east of a line from Rapid City, South Dakota to Fargo, and south of I-94, including eastern South and North Dakota, Nebraska, Kansas, northwest Missouri, western Iowa, and southwestern Minnesota. Day 4: LOW (5-10%): Greatest risk area is east of US 83 but west of I-39 and I-55, mainly south of I-94, including the eastern Dakotas, Nebraska, Kansas, Missouri, Iowa, much of Minnesota, western Wisconsin, and western Illinois. Day 5: LOW (5-10%): Greatest risk area is east of US 81 to I-69 and I-65, mainly south of US 10, including the far eastern Dakotas, eastern Nebraska, eastern Kansas, Missouri, Iowa, southern Minnesota, southern Wisconsin, Illinois, western Kentucky, western Indiana, and southwestern lower Michigan.
Click Here For The Days 3-5 Risk Map (opens a new window)
The main focus of the long-term period will be the emergence of the newly developed northern Rockies low pressure area into the Plains and also its attendant frontal boundary or boundaries. High pressure is expected to continue to slide off to the east or southeast through the period, bringing a return of southerly winds to a larger area from the start to end of the forecasting period. The area of low pressure will also move to the east, but through time is expected to align its associated frontal boundary in a west to east fashion versus one more progressive that is typically in a north to south layout. Along and south of the boundary, southerly or southwesterly winds from source regions mainly in far northern Oklahoma, southern Kansas, and southwestern Missouri will blow to the north and northeast especially on Days 3 and 4, with the source region shifting into southern Missouri and northern Arkansas by Day 5. Precipitation will become more widespread through time, with the highest coverage currently expected during the Day 5 period. Insect migration risks, therefore, will also increase through time. On Day 3, the best risk is west of I-35, with the risk shifting east to the US 51 and I-39 corridor on Day 4, and finally possibly as far east as the I-69 and I-65 corridors by Day 5.
There is fairly good confidence in the forecast even this many days in advance, but trap counts for corn earworm have actually dropped in or close to the source region in the past few days (notably across southeast Missouri and northeast Arkansas), so the overall insect migration risk is kept pretty low for the time being. While mainly a local developer and migrator, we would encourage those with interests in western bean cutworm to monitor traps later this weekend and early next week across especially northeast Nebraska, northwest Iowa, far southeastern South Dakota, and also possibly far southwestern Minnesota for any sudden spikes that may be associated with a local or regional migration. Western bean cutworm counts have really increased across especially southern Nebraska in the last few days, so this upcoming weather system and its associated southerly and southwesterly winds will provide the opportunity to observe any possible migratory habits of this newer pest to the 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
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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