IEM Daily Feature
Wednesday, 08 May 2013

Short vs Long Term

Posted: 08 May 2013 05:45 AM

The featured chart shows the 30, 90, and 365 day trailing precipitation departures for statewide areal averaged precipitation since 1 April 2012. While the short term metrics are around +4 inches above average, the long term deficit has only improved by two inches or so. The reason is that late April and early May 2012 was a wet period before the drought got started, so very wet days this year are replacing wet days last year resulting in little net change. The long term deficit will not be erased until either we have a wet June and July, or we simply reach August and that period drops out of the 365 day window. These time scale interactions are what makes drought analysis difficult.

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