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Publication Abstract

El Nino 1997-1998 in the Midwest Changnon, Stanley A., Steven D. Hilberg, and Kenneth E. Kunkel, 2000  Illinois State Water Survey, Champaign, IL,  ISWS DCS 2000-01    Full Text Available
An anomalously warm El Niño event developed in the eastern tropical Pacific Ocean during May-August 1997. El Niño events have become recognized as capable of having major effects on atmospheric circulation patterns over North America and elsewhere, leading to predictable outcomes for future seasonal weather conditions.

The source of the nation's official long-range predictions, the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center (CPC), began issuing forecasts in May 1997 about the event's development and growth to near record proportions. The emerging El Niño was expected to match or exceed the El Niño of 1982-1983, the strongest of this century. Predictions of the future weather conditions expected over the nation, as a result of El Niño's influence on the atmosphere, also were issued by CPC beginning in June 1997. Basically, these and subsequent predictions called for a fall, winter, and early spring in the Midwest that would have above normal temperatures and below normal precipitation. The predictions also called for storms and precipitation to increase in other parts of the nation, particularly in the South and West Coast areas.

Media and wide public interest in the evolving record event brought inquiries to the Midwestern Climate Center (MCC) during June 1997. At that time, MCC leadership launched special studies and efforts related to the El Niño event, which included:

  1. a climatological reanalysis of past El Niño events and the associated weather conditions in the Midwest,
  2. the issuance of outlooks based on these studies, and
  3. the collection and analysis of data on the impacts caused by the El Niño-generated weather conditions in the Midwest.

This decision was in keeping with past MCC research policy that has focused on assessing extreme Midwestern weather conditions like the 1988 drought (Changnon, 1991a and b), the 1993 flood (Kunkel, 1996; Changnon, 1996), and the 1995 heat wave (Kunkel et al., 1996; Changnon et al., 1996). These studies also focused on identifying and quantifying the impacts of these extreme events. The findings of such activities help the MCC respond rapidly and accurately to numerous regional inquiries for data and information about such extreme events. They also help the MCC prepare for effectively addressing similar events in the future.

During the El Niño event, beginning in June 1997 and ending in May 1998, the MCC scientists issued several climate outlooks about future Midwestern conditions. These were basically probabilistic-based statements and focused on the winter of 1997-1998, spring 1998, and summer 1998 outcomes. During the El Niño event, the MCC staff collected and recorded all the relevant weather data for the Midwest. Data defining the impacts of El Niño-generated weather events were collected from August 1997 through August 1998.

This report presents information about MCC activities related to El Niño in 1997-1998. It includes three sections: the predictive outlooks issued, a climatic assessment of monthly and seasonal weather conditions during the event, and a description of societal and economic impacts caused in the Midwest. Recommendations are offered in the section "Conclusions and Recommendations" for addressing future El Niño events and the handling of long-range predictions.



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