Weather Blog

Like to track rain? You'll be cuckoo for CoCoRahs

Like to track rain? You'll be cuckoo for CoCoRahs
It's a common joke: "Why do they measure the weather at the airport? Nobody lives there?" 

Of course, most official measurements are at an airport because pilots are most in need of up-to-the-minute weather observations, and since that's where the weather spotters worked and the equipment was there anyway, might as well have it do double duty and become the official data center.

These days, most weather observations are automated, although there is still some human aspect at major sites. But if you're tired of looking out your window in Sammamish to a rushing river from a heavy deluge and hearing Sea-Tac Airport only had a Trace of rain that day, here is your chance to help get your neighborhood on the weather map.

The National Weather Service is about to introduce a new program to Washington state called "CoCoRahs", which is GAS (Government Acronym Speak) for "Community Collaborative Rain, Hail & Snow Network."

Basically, they want you to help them track daily rainfall, hail and/or snow. Anyone with a standard rain gauge can volunteer to join the network -- be it a residence, business or school -- and report your daily rain to a web site. The NWS will then use that data to better understand local variances in rainfall -- and those variances are quite large in Western Washington due to our terrain and vast topography.

CoCoRahs started in Fort Collins, Colorado in the late 1990s after a devastating flood.  Researchers went back to look at the precipitation data that led to the flood and found that the rainfall had missed all the official gauges.

Colorado State Climatologist Nolan Doesken developed a new volunteer observing network to fill the gaps between official gauges called CoCoRahs. The network has spread across the country and will be introduced in Washington on June 1.

To participate, they ask that you have at least a standard 4" rain gauge. You can buy one on their site for roughly $29 including shipping or find one at a local hardware or marine supply store.  Those of you with fancy digital home weather stations can use that rain gauge just fine.

Ted Buehner with the Seattle office of the National Weather Service says the information can be invaluable. Members will be able to give real-time storm reports at any time and that information will make it back to Seattle weather forecasters.

He pointed out the vast differences in rainfall totals during some of the most recent storms, such as the early December floods last year.  There were very few rain gauges to measure just how much rain fell in the Willapa Hills that lead to the massive Chehalis River flooding.  There was also limited rainfall information on the Eastside during that storm, and remember that image of flood waters rushing through the shopping area of Woodinville?

Daily rainfall totals should be reported in the early morning hours, and all data will be available on their web site for any to see.  Their goal is to have an observer in every square mile across the state, making it much easier to track the rain in your neighborhood, instead of having to rely on what may or may not be a nearby airport.

You can find more information at  The site also has tips on how to properly set up a rain gauge, how to report the rain, and information on training seminars.