To help size drainage, I'd like to calculate the maximum rainfall intensity for my particular location. How do I do that?
I've found data sources that will give me the average number of inches of rain per month. However, storms might last for only a few hours or a day, and intensity might vary, so it's not clear how to get from average precipitation over a month to the maximum amount of precipitation per hour at the height of a storm. Is there a conversion factor? Or, is there a site or calculator or chart I can use to look up the rainfall intensity for my area?