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 12, 2007, 7AM central time
Short-term (present to 48 hours):
Day 1 (Thursday 7/12/2007 noon to Friday 7/13/2007 noon): Relative Risk of Insect migration into the Midwest: VERY LOW (2-5%): Greatest risk area is south of I-70 and west of US 71, including much of Kansas.
Click Here For The Day 1 Risk Map (opens a new window)
The surface weather map this morning has the cold front that passed rather quickly through the forecasting region earlier this week all the way into the Atlantic Ocean to the east and then across the southern United States before turning northwest into Oklahoma. At the western end of the front, a cluster of showers and thunderstorms is observed currently in far southern Kansas into Oklahoma on southeasterly winds feeding into Kansas from northern Texas and Oklahoma. Elsewhere, the rest of the forecast area is bathed in westerly or northwesterly winds and no precipitation.
As the next 24 hours progresses, the focus for any insect migration risk will remain across Kansas as a repeat performance of last night is expected to occur again tonight, but perhaps a little bit earlier than what occurred last night. Southeasterly or southerly winds will continue to feed into Kansas specifically, and with the chance of precipitation, a Very Low risk of insect migration is forecast south of I-70 and west of US 71 in Kansas. Elsewhere, the westerly or northwesterly winds are expected to continue, and while a chance of precipitation exists across the Great Lakes region, wind flow in this area is from unfavorable source regions for insect migration so no risk of insect migration is forecast outside of Kansas for the next 24 hours.
Day 2 (Friday 7/13/2007 noon to Saturday 7/14/2007 noon): Relative Risk of Insect migration into the Midwest: NONE
Click Here For The Day 2 Risk Map (opens a new window)
High pressure slides to the southeast, reaching an axis from southern Missouri east into Kentucky and southern Ohio. A low pressure system in quick northwest to southeast flow around the deep low pressure near James Bay is expected to slide to the southeast into the Great Lakes, producing precipitation in its proximity. Wind flow, however, is expected to continue from a northwesterly or westerly direction across the entire forecast area as high pressure builds in briefly behind the low pressure system so despite possible precipitation serving as insect drop zones, insects are not expected to be moving in such a wind pattern. Therefore, no risk of insect migration is forecast during the Day 2 forecasting period.
Long-term (Day 3 to Day 5: Saturday through Tuesday):
Days 3-5 (Saturday 7/14/2007 noon to Tuesday 7/17/2007 noon): Relative Risk of Insect migration into the Midwest: Day 3: VERY LOW (2-5%): Greatest risk area is south of a line from Rapid City to Sioux City, Iowa to Paducah, Kentucky, including southern South Dakota, Nebraska, Kansas, southwestern Iowa, Missouri, far southwestern Illinois, and far western Kentucky. Day 4: LOW (5-10%): Greatest risk area is west of I-35 and southeast of a line from Rapid City to Fargo south of US 2, including southeast North Dakota, southeast South Dakota, Nebraska, Kansas, southern and central Minnesota, western Iowa, and northwestern Missouri. Day 5: LOW (5-10%): Greatest risk area is along and south of I-94 west of the Mississippi River, including southern North Dakota, South Dakota, Nebraska, Kansas, central and southern Minnesota, Iowa, and Missouri.
Click Here For The Days 3-5 Risk Map (opens a new window)
The next possible opportunity for more widespread insect migration may come next week as heat and humidity build back into most of the Plains and Midwest although some uncertainty in the depth of the heat and also, more importantly, the strength of southerly winds that may help produce insect migration chances exists in the forecast this many days out.
On Day 3, high pressure is expected to slide to the southeast into the Mississippi River valley. Southerly winds are expected to develop mainly across the southern and western portions of the forecasting region, largely southwest of a line from Rapid City, South Dakota to Paducah, Kentucky as the high moves east. Precipitation, however, is expected to be isolated and mainly focused closer to a developing low pressure system over eastern Montana, so risks are kept in the Very Low category across the southwestern portion of the Plains and western Midwest. No risk of insect migration is forecast further northeast where high pressure is expected to remain in control or wind flow rather weak, precluding any insect migration risk.
By Days 4 and 5, the low pressure area will likely shift to the east, but the cold front in association with the front is expected to possibly turn more east to west near the I-90 or I-94 corridors, mainly west of the Mississippi River. Southerly winds are expected to increase in speed by Day 4 and also spread to the east on both Days 4 and 5, with precipitation chances increasing closer to the front. On Day 4, a Low risk of insect migration is forecast west of I-35 and south of US 2, and also southeast of a line from Rapid City to Fargo. As the front washes out and a new low pressure develops over eastern Montana by Day 5, the insect migration risk level is maintained in the Low category and is expanded east to the Mississippi River and south of I-94. Very Low risks are expanded further east into the I-69 and I-65 corridors as well as southerly winds expand to the east.
We will continue to monitor the longer range period and provide updates in tomorrow’s forecast. Some modest increases in corn earworm trap counts have recently occurred in southeast Missouri in the past few days so trap counts will continue to be monitored in and around this area for the possibility of the next generation developing and moving north on southerly wind flow in greater numbers.
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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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