These maps display precipitation vs precipitation event return frequency for 24 hour periods. The loop animates 6 hour return frequency. Values below 1 represent the ratio of precipitation vs the 2-year return frequency. Values above 1 indicate the frequency return in years. In other words, if the value is 25, then the rainfall amount is at the 25-year return frequency mark. Precipitation frequency values were obtained from the NOAA Atlas 14 dataset (https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_ak.html).
Yesterday's map is using APRFC's QPE for rainfall. Today through Day 3 uses APRFC's QPF.