It would be interesting to repeat the comparison for many specific locations, then plot the measured variance geographically as a "heat map" or landscape of err

It would be interesting to repeat the comparison for many specific locations, then plot the measured variance geographically as a "heat map" or landscape of error [1]. Are there patterns visible that could be attributed to local geography, population density, or other factors? [1] It could be done, for weather.gov [2], using only data available from the web site [3]. [2] I don't really care about the other forecast sources. [3] To trust rainfall observations obtained from weather.gov in order to compare them to predictions made by weather.gov seems vaguely wrong but there is no other comparable source of observations. They are physical measurements, after all. [4] Some geographic areas probably have a coarser net of observation points. In some places, e.g., San Diego, the weather is inherently easier to predict. Some local forecast offices may be more skilled than others.