The IEM processes a dataset of one minute interval precipitation observations from the Des Moines Airport. Using this dataset, we can compute the average contributions to yearly totals for each minute precipitation rate. The two values shown are total number of minutes with precipitation and total precipitation volume. The sensor records the data in an increment of 0.01 inches, so that intensity is the lowest observable and the plot shows that it dominates the count and volume percentages. Rewording, over 80% of the minutes that reported precipitation and over 60% of the total rainfall fell at minute rates of only 0.01 inches. So light rain is very significant to our yearly precipitation totals! The bottom chart displays the same data, but with a log scale y axis. The regime shift at 0.14 inches and higher is likely due to a quirk with how this dataset is reported. An under-catch multiplier is applied at such intense rates.

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Tags:   precip