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For weatherphiles, those of us who love weather in all its varied forms, extreme or rare weather events often holds the greatest allure. Spawned by our love of statistics, one extreme event that catches our attention is the record-breaking day. The local news reports love to feature a record-setting weather day. The most frequent are temperature extremes. Whether a record hot day or record cold day, it is sure make headlines. Temperature records are kept for annual extremes, monthly extremes and daily extremes. Today wherever you are, there are record maximum and minimum for the date lurking in some data set.
If I told you that today's weather set a record for either the maximum or minimum temperature, you would likely respond with a modicum of interest. If I told you that this day broke both the daily maximum and minimum temperature record, you might exhibit degree of incredulity. How can both records be broken on the same day? Can't happen, you say. Ahhh, but it can, and, though a rare event, has happened across the United States more than a couple dozen times. I call such days: double record days. Before I tell you how both records could be broken on the same day, I must set a couple ground rules. First, what records are we talking about? Here, I am looking at the temperature extremes of hot and cold during one specific calendar day, be it May 27 or December 2, and how the specific readings on that day in 1935 or 2003 related to the extremes measured on all of those dates over the course of the climatological station's observational history. Second, the climatological station at which the events occurred must have a data history at least several decades long. If the data span is too short, the odds of breaking a temperature record, even both, are fairly high. For example, the first year of record-keeping sets the initial marks for both maximum and minimum temperatures. So that day doesn't count. The next year on that date, the extreme temperatures may break either the maximum or the minimum mark of the previous year, or both, or neither. As the length of record increases, the likelihood of breaking either temperature extreme decreases as does the likelihood of breaking both within the same day. How Can Both Maximum and Minimum Records Be Set on the Same Day?While any day can potentially set new temperature extremes for both the maximum and minimum, certain weather situations are more likely to do so. As well, certain locations have a greater likelihood to experience a double record day. In the United States, for example, most double-record days have occurred in the arid and mountainous western regions of the nation: Utah and Nevada. But Florida has registered a couple events as has Hawaii.
The copyright of the article A Record Setting Day in Meteorology is owned by . Permission to republish A Record Setting Day in print or online must be granted by the author in writing.
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