Elias Johnson

Publication Date


Document Type


First Advisor

Lahey, James F.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Earth Science


Long-range weather forecasts--Illinois--Sycamore; Sycamore (Ill.)--Climate


While investigating the variable manner in which temperatures at Sycamore, Illinois change from their high values of summer to their winter minima, a pronounced drop in the 40-year average of the running 5-day mean maximum temperature was noted during the latter part of September. It was then decided to investigate the character of declines in the maximum temperature at Sycamore during September, and, if possible, relate these temperature drops to hemispheric changes in sea-level pressure. If one should note systematic and unique changes In hemispheric pressure fields occurring prior to various kinds of temperature breaks, climatological estimates of future temperature breaks might be enhanced by use of the diagnostic aspects of these prior broadscale pressure changes. The techniques used 'to accomplish this analysis are as follows: 1) establish homogeneous samples from the total population for analysis by finding September 5-day mean maximum temperature drops which are approximately equivalent in character. 2) establish 5-day mem sea-level pressures and variances of pressures for these homogeneous samples. These sere computed for a grid of 126 points covering the entire northern hemisphere mid-latitude portion of the western hemisphere. 3) establish the geographic areas where these means are significant by comparing them statistically with a random set of 5-day mean sea-level pressures and variances. 4) establish the extent to which the significant 5-day running mean sea-level pressures vary from a commonly recognized norm.


Includes bibliographical references (pages [112]-113)


ix, 113 pages




Northern Illinois University

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