Apologies for resurrecting an old topic, but I've been wondering about this question also. Lots of rain this week here, so I started looking to see if the reporting lined up with my local PWS.
Here is what is on the Iro:
But the data on WU (for KNJPRINC8, which is the same as MID_E7502) shows:
And on Findu for EW7502, it shows:
You have to squint at the graph, but the same daily accumulation (blue line) seems to be the same as what is reported by WU.
I was wondering if it could be some timezone shifting going on, which is annoying but not a big deal, but the numbers don't quite add up either.
This all came about because of the helpful posts by @johnny2678 and @boldblue737 to get on the PWS bandwagon. But after a little exploration of my currently selected PWS, I noticed the discrepancies above.