IEM Daily Feature
Friday, 05 October 2012

When did the drought start?

Posted: 05 Oct 2012 05:45 AM

Iowa remains in the firm grasp of a drought, but when did it start? It is hard to define when a drought starts as the term "drought" is ambiguous and it takes some amount of time of dry weather before the term can apply. The featured chart looks at the running departure of statewide precipitation over three different windows of time for a period around 1988 and our current drought period of 2012. For this year, this analysis would clearly indicate that significant deficits started showing up in May. Although, a closer look shows somewhat drier conditions existing since September of 2011. Let us compare 2012 with 1988 shown in the top chart. Significant deficits started appearing in March of 1988. If the 2012 drought started in May and 1988 in March, this may provide some insight into why agricultural crops were not a complete failure in the state this year. The reason being there was some soil moisture available to start off the growing season and some precipitation came in late August/September to help out. Notice how the 365 day departure degraded in Aug/Sep for 1988 and flattened out for 2012.

Good = 43
Bad = 27

Tags:   drought   2012   1988