IEM Daily Feature
Wednesday, 07 July 2021

Gridded Percent of Average Precipitation

Posted: 07 Jul 2021 05:48 AM

Yesterday's IEM Daily Feature discussed some of the pros and cons of using a map of contoured point observations of precipitation percentage of average. Today's plot uses a high resolution grid product from NOAA called MRMS and compares against an analysis of climatology based on point observations. The resolvable detail is much higher, so an obvious question is why anybody would want to use the courser product featured yesterday? Well, the map today is not without its own blemishes. First up, this map is heavily based on RADAR derived estimates, which have they own set of caveats and issues with things like wind farms and over estimates due to hail. Additionally, confidence in these estimates decreases with increasing distance from the nearest NEXRAD site. Having said that, the general spatial pattern nicely matches yesterday's map (which is should as they both are generally valid maps) with very dry conditions shown near Waterloo and other places over northern Iowa along with rather wet locations over southeastern Iowa.

Good = 12
Bad = 1
Abstain = 1