IEM Daily Feature
Thursday, 20 September 2007

Increased variability

Posted: 20 Sep 2007 01:04 AM

The featured plot graphs out climatological daily variability of high and low temperatures based on statewide observations dating back to 1951. Disregarding the day to day noise in the plot, a couple of things stand out. Firstly, temperatures are much less variable in the summer. The primary reason for this is the prevalence of a humid air mass acting to modulate our temperatures. Secondly, the winter season is most variable due to the influence of snow cover on our radiation budget and advection of warm or cold air masses by storm systems. For September, a sharp increase over summer is noticed as each day becomes more variable. The reasons for this increase include decreasing humidity levels and the return of strong cold air surges from Canada.

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