WRAL WeatherCenter Blog

I recently bought a rain gauge and I am curious if it is similar to what you use. It is a glass tube about 5 inches long and 1/2 inch wide and is marked in 1/4 inches. I live in Garner and it always seems to measure more than what the weather bureau says we had. As of 3 PM today, (Dec 26) it measured 4 inches of rain. I am curious if we are just getting more rain lately than Raleigh, or if the gauge is inaccurate.

Posted December 29, 2007

MIKE MOSS SAYS:         Mike,     That is a very small gauge compared to an "official" gauge (the NWS standard gauge has an 8 inch diameter, for example). Also, you don't mention over what period of time the 4 inches you measured was obtained (i.e. are you certain you emptied the gauge after some previous rainfall events?) Assuming you did, it strikes me more as some kind of a location issue than an inaccurate gauge per se. The reason is that very small gauges would often be more subject to undercatch (showing less precipitation than larger gauges) errors due to wind and to outsplash effects than to overcatch errors. You would probably want to make sure your gauge is not in a location where water may be dripping off the edge of a roof or a kink in a tree limb, and that it is not located where water droplets splashing up from surrounding ground or a deck surface, etc around it may find their way into the gauge.

For the date you mentioned, I took a look at precipitation maps based on combined radar and rain gauge estimates for the region, and it did not appear there would be any reason for such a high reading in the Garner area relative to other nearby locations. You can check your readings against other sites across Wake County at this address:

http://www.cocorahs.org/Maps/ViewMap.aspx?state=NC&county=WK

Note that the date can be changed by using the up/down buttons and then clicking "Get Map."

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  • Made In USA Dec 31, 2007

    Thanks for the info about the CoCoRAHS rain measurements. The website is loaded with information. For $22, that's a bargain for an accurate gauge. I saw there is already one recording station in Apex, but still may try and join in on the fun. Online training is idea too. Again, thanks Mike for the info!

  • Mike Moss Dec 31, 2007

    Made in USA, There are a range of home weather station options out there, most of which are plenty accurate for home/hobby use and which cover a large span of budget needs. For these electronic systems, just type "home weather station" or some similar phrase in a search engine - you'll find systems from Davis, La Crosse, Rainwise, Texas Instruments and more. For a simple rain gauge, you don't really need an 8 inch diameter unit. In fact, the recently deployed national CoCoRAHS precipitation reporting network depends on a good quality 4-inch plastic gauge, as seen at http://www.cocorahs.org/Content.aspx?page=MeasureRain. Good luck, and enjoy your measurements!

  • Made In USA Dec 30, 2007

    ^ And is affordable? >

  • Made In USA Dec 30, 2007

    I love keeping tabs on the weather outside, especially during this drought. I wonder where I can find an accurate and good weather station that would be comparable to what RDU uses...like a wind gauge and an 8" rain gauge, along with the wind speed?