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Abstract
The Climate Prediction Center has stated that an El Nino episode began in May or June of this year, and is continuing to strengthen. The Climate Prediction Center also now expects the El Nino to continue to strengthen into our winter. There is a strong correlation to warmer than normal winters in the Upper Midwest and Great Lakes. With the traditional crops thought to be behind by 2 to 3 weeks in the corn belt, we chose to research if El Nino can effect September and October weather in the corn belt. Our findings show that the chance of an early frost is lessened in the current developing El Nino stage.
El Nino is an ocean phenomena where the sea surface temperature between the west coast of South America and Australia begins to warm to temperatures above normal. The El Nino region is divided into four parts: region 1, region 2, region 3, and region 4. The largest region, and region most followed is an area encompassing both region 3 and region 4, being called region 3.4.
A moderate strength El Nino has temperatures between 1 and 2 degrees celsius above normal. A strong El Nino has temperatures 2 degrees celsius above normal or greater. The Climate Prediction Center says all indications are that the El Nino will continue to strengthen into winter.
The traditional crops grown in the Upper Midwest and Great Lakes( corn, soybeans, sugar beets) are said to be 2 to 3 weeks behind in development as of this time (August 19,2009). El Nino has a significant effect on winter weather in the Upper Midwest and Great Lakes(UM/GL from now on). Temperatures can average much warmer than normal in December, January, and February. But can El Nino’s warming effect on the UM/GL start in fall, thus helping to avoid an early frost? We studied September and October weather for 6 cities throughout the corn belt. The cities are; Saginaw, Lansing, Indianapolis, Rockford, Madison, and Des Moines. We looked at 10 years since 1950 that had an El Nino starting development in the April to June time frame. We found that in almost all cities the 10% chance of the first 32 degree reading was delayed by around two weeks. To put this is sensible terms, an earlier than normal frost, which occurs in one out of ten years, is shifted from mid to late September to early to mid October. This would be favorable for the continued development of the corn belt crops. The following graphs show how much delayed on average the early frost has been in comparable El Nino years for individual cities.
To explain our methodology, we’ll start with Saginaw, MI.
In the chart below, you’ll see the 10% chance of a 32 degree reading is September 27. That means one out of ten years hits the freezing mark by September 27th. 5 out of 10 years(50% chance) drop to the freezing mark by Oct. 12th, and in 9 out of 10 years a freeze has occurred by Oct. 28th. The second chart below shows the actual first 32 degree reading in each of the 10 El Nino years studied. You can see that the first freeze in every year but one was later than the 10% chance of a frost date(the early freeze date). In fact, Saginaw’s freezes during the 10 El Nino years average 12 days later, or around October 9th. You’ll notice the 50% chance of a freeze actually occurred near the normal timeframe. What’s interesting is the actual freezes occurred much earlier than the 90% chance of a freeze date. This tells us that an early freeze is not likely, but when the freeze finally does occur, it’s not late either. Following this pattern, the Saginaw area would have the first freeze most likely occur the second week of October.
Here’s the El nino years average first freeze dates of the additional cities:
Lansing – October 4th
Indianapolis – October 20th
Rockford – October 13th
Madison – September 30th
Des Moines – October 10th
All of these dates are 9-24 days later than the early freeze date
Precipitation
The past similar El Nino events (’65, ’72, ’82, ’91, ’94, ’97, ’02, ’04) have produced Septembers and Octobers that were dryer than
normal, but Augusts that were average to more than average rainfall. The data collected confirms these trends. As of August 19th the six cities studied currently are on track to receive the normal amount of precipitation. Indianapolis and Lansing already have more than an inch higher the normal while Saginaw, Des Moines, Madison, and Rockford are all within a half an inch or less of the their August normal. After looking at the past 10 El Niño years that were similar to the one currently taking place, there appears to be a definite trend for the months of September and October to be dryer than normal. The anomalies for all 10 years of each city were summed together, and each city for both September and October had a negative answer. For only a few years a couple of the cities experienced increased amounts of precipitation. September of 1965 showed a very large amount of increased rainfall. This is believed to be the product of the remnants of Hurricane Betsy, which came through the Ohio Valley in mid September. However, both months in 1972 and October of 1991 had an average of increased rainfall for unknown reasons. Using the past history of the comparable El Nino years, there is a high probability the Corn Belt will have a dryer than normal fall. There is only a small chance some cities could get normal to slightly more than average amounts of rainfall.At the right are the graphs showing precipitation for each city. Each opens in a new window.
Conclusion
Before a conclusion is stated, we should point out that weather follows patterns, but can at times forget about the rules. Do not make any significant financial decisions on this research without realizing that the actual weather of this coming fall may not follow the patterns of the past.
Based on our research, there is a strong chance that the first freeze in the corn belt states will be right around the normal date, and not early. This should allow the crops to finish maturing. There is also a strong chance that it will be a dryer than normal fall. Above normal rainfall would probably be brought by a tropical system moving into the Eastern Great Lakes. At this time the tropics look very quiet. The El Nino also tends to produce a stronger westerly wind in the tropics, reducing the amount of tropical systems. So a dry fall looks to be fairly likely.
Here’s a summary of the impact of expected weather on individual crops:
Corn – No early frost should allow the corn, now 2-3 weeks behind, to mature. The rainfall in most of the corn belt the past 30 days has been ample, with the exception of northeast Illinois, and the western two-thirds of Iowa. In these areas, rainfall has only been 2 to 3 inches below normal. So the corn crop probably has as much moisture as it needs to fill out the ears.
Soybeans – No early frost should allow the soybeans to mature. Temperatures into early September look to be slightly below normal, possibly limiting the size of the bean at harvest. Dryer than normal conditions in October could make for a speedy harvest.
Sugar beets in Michigan - The size of the beets could be smaller than last year due to dryer conditions in September. The dry conditions, however, could also boost sugar levels, helping to cancel out the smaller size of the beets.
About the authors
Mark Torregrossa – Is Chief Meteorologist at WEYI/NBC25 in Flint/Saginaw/Bay City/Midland, MI. He has a B.S. in meteorology from Northern Illinois University ’89. He was selected Michigan Farm Bureau Agricultural Communicator of the Year in 2008. He can be reached at markt@speednetllc.com.
Scott Ozog - Currently a student at Central Michigan University in Mt. Pleasant, MI. Looking to graduate in the spring of 2012 he is on his way to earning a B.S. in both Meteorology and Geographic Information Science with a minor in mathematics. He can be reached at ozog1sc@cmich.edu
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