Producing a drought analysis is very tricky business as generating a single classification that encompasses precipitation departures over various time scales is fraught with peril. It also does not help that summer time precipitation tends to be very spatially variable as individual thunderstorms have a footprint much smaller than what the drought monitor is built to capture. The featured map attempts to illustrate this by combining the most recent drought monitor analysis and climate station precipitation departures measured over 30, 120, and 365 days. The departures are expressed in terms of standard deviation (sigma) and colored in a way that aligns with a drought monitor classification metric. So a comparison is readily apparent between the drought situation in NW Iowa and that in southern Iowa. The bulk of the significant dryness in NW Iowa is on longer time scales and southern Iowa is a much more recent / flash drought situation. In the face of conflicting precipitation metrics, it is always good to look at impacts. In this case, low river flows, dry soils, and crop stress are generally common over all the analyzed drought areas.

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Tags:   drought