Gauging rain isn't a science

Downpour: How much water fell Thursday is up for discussion, as Weather Service and backyard devices give different results.

August 28, 1999|By Linell Smith | Linell Smith,SUN STAFF

Seven-something inches of rain in Woodlawn? Four-and-a-half at Fort McHenry? A measly inch at the airport? Just how do those weather people record the downpour that almost swallowed the car and turned the basement into an aqua-aerobics palace?

When measuring rain, it's always best to use a complex, hard-to-explain system of calibration. Meteorologists for the National Weather Service rely on an 8-inch standard gauge mounted within a system of metal cannisters (designed with overflow capacity) to determine precipitation at BWI airport and other strategic outposts.

Meanwhile, the rest of us can purchase a mostly-official plastic rain gauge from a home and garden center. Designed to use the Weather Service's method of measuring precipitation per square inch, such gauges cost less than three bucks and are usually more accurate than buckets or aluminum pots.

One instrument is the plastic combination rain gauge made by Springfield Precision Instruments of Wood-Ridge, N.J. Its 1-inch capacity base unit has a ground stake that allows it to measure sprinkler or field watering levels. The accompanying 5-inch-capacity rain gauge can be mounted in the base unit or on a fence post.

"The rain gauge measures rainfall the same way the National Weather Service does," says Jim Csaposs, product engineer for Springfield. "If the weather bureau says there were 3 inches of rain in your area, your home-owner's rain gauge should report that, too."

Talk about relief!

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