Over the last 24 hours or so the area I live in near Minneapolis, MN had some intense rain. While the official total at the Mpls airport was 1" some suburbs to the north got over 10". I live about 90 miles east and had the opportunity to watch the storms with the Blitzortung lightning data and be at home to have cell after cell pass by, with what I would consider 'hurricane strength' rain. This isn't something we normally get. A thunderstorm and hard rain for a few minutes, or an all afternoon slow soaker is much more common.
But, as each cell passed, with some very light hail sometimes, there would be much cloud to ground lightning, almost no wind and very very heavy rain.
My total was about 5.51" all measured with tipping bucket devices.
Here's the odd thing, as reported by a friend who also likes weather and has two tipping buckets and one 3" tube type collector.
After a whole afternoon of storms, he decided he'd better empty his tube gauge. It was very close to 4.0". The two tipping buckets were at about 3.5" which is understandable since I believe they tend to under report in heavy rain. This fellow is not one for hyperbole or stretching the facts, a lifelong trained engineer who's daily work required precise measurements. The gauges are as perfectly placed as one might be able to get them, no trees, overhead diverters, etc. and again wind was not a factor.
After dumping the 4.0 from the tube gauge, he went to bed and this morning went to see the additional total, which was now 4.9'. So his total according to the tube was 8.9", while the total on the tipping buckets was between 5.5 and 6". This total was in comparision to my 5.51", although we are about a mile or so apart.
He has been baffled for an explanation. I have no problem accepting the likely truth to the 8.9", local variation was certainly evident with each cell passage, and it was absolutely torrential when it came down with some of passages.
He is pondering how there could be such a difference in his measurements. I would assume that the gold standard would be the tube gauge. Can very heavy rains get a tipping bucket that far behind real accumulation?
Being in the country we even speculated as to some creature urinating in the tube gauge, but the bear would have to be exceptionally nimble and bigger than most to get the perfect shot into the gauge.
I'm hoping someone with an interest in rain and measurement would have some insight. About the only place I could think would have these impressive amounts of rain would be the hurricane areas, and perhaps monsoon areas in the SW but usually I don't see accumulations anywhere close to what we had in about 18 hours.
Comments? And no, neither one of us brews our own moonshine or are prone to hallucinations!
Dale