Complete report not currently available online.
During El Niño events, the Midwest region is one of the more difficult
areas in the United States to forecast trends in climatic patterns and especially
their influence (or lack thereof) on synoptic-scale weather events. For example,
during the 1982-83 El Niño the Midwest was located about midway between
enhanced anticyclonic (cyclonic) flow to its north (south) and in a zone of
weaker-than-normal westerly flow. Any slight shift in this mean seasonal circulation
anomaly pattern, particularly in the north-south direction, would most likely
change the weather conditions over the Midwest. In winter, this not only could
alter the temperature and precipitation patterns, but it could cause the precipitation
to change form from rain to snow, or vice versa. The overall goal of this project
was to examine the effect the 1997-89 El Niño had on the anomalously
low and/or high precipitation episodes that occurred across the Midwest during
the winter season. The main work consisted of looking at individual case studies
of the synoptic-scale circulation patterns, including the meandering of the
jet stream, during both dry and wet periods.