CoCoRahs (Community Collaborative for Rain, Hail and Snow) is a national network of weather observers just like our members. Several of us are members of CoCoRahs. If you’re not a member and can spare 10-15 seconds the morning before or after the Net, think about joining CoCoRaHS. It’s free.
The link below is a cartoon that goes over the basics of measuring rain but it also has some suggestions for measuring very heavy rainfall, including one hint that I was unaware of! If the inner cylinder of your raingauge is in place and the rain has overflowed into the outer cylinder you can estimate the amount in the outer gauge by seeing how high it is on the scale of the inner gauge. Every 0.10 of the water mark on the inner gauge you will have approximately 1.00″ of water in the outer gauge. Sound confusing? Watch the cartoon. If you don’t have a Stratus rain gauge, buy one! It is the most accurate way of measuring precipitation. They are available on the CoCoRaHS website for about $31.