Apple Weather Total Precipitation Values Incorrect

The total daily precipitation values shown at the top and bottom of the screen are not accurate. Example shown in the below screenshot, the daily summary at the bottom states there will be 26mm of snow tomorrow, the value at the top of the screen says there will be 2mm of snow tomorrow, and if you add the hourly values from the graph there should be 18mm of snow (6mm+6mm+5mm). How can all three of these values be different? Something is not being added up correctly.