Hundreds of Colorado residents have been on full alert this week to accurately measure and report moisture falling from the winter storm.They are volunteers for the nonprofit group CoCoRaHS, which stands for Community Collaborative Rain, Hail and Snow Network.Volunteers come from a variety of backgrounds and represent all age groups.Participating in CoCoRaHS is as easy as purchasing a $25 approved rain gauge and placing in it your yard. Daily observations are then made and reported to the CoCoRaHS Web site. The reports plot in real-time to an interactive mapping database."I enjoy being part of CoCoRaHS," said Arapahoe County observer Dorn Nienaber. "It takes less than 5 minutes a day and it's interesting to see the difference between my report and others in the county."CoCoRaHS data is archived and used by numerous local organizations, including media outlets, the Urban Drainage and Flood Control District, and city governments.On a national level, CoCoRaHS data is used in research projects by government agencies such as NASA and NOAA.The network is active in 49 states and has nearly 20,000 volunteers. Minnesota will join CoCoRaHS in December, making the national map complete.In Colorado, hundreds of volunteers report daily precipitation, but hundreds more are needed to fill in numerous gaps within the network."Our goal is to have an observer every square mile in populated areas," said state coordinator Henry Reges. "But more than one is OK too. If you look at the map and there appears to be a data point where you live, that's OK, we'd gladly welcome you as an observer."CoCoRaHS has been active in the Denver metro area since 2002 and the data is proving to not only be useful, but also educational.What was first thought to be an error in the dataset after reports came in from the March 2003 blizzard actually revealed an interesting precipitation pattern near the town of Lyons in Boulder County. Snow reports from that area were several inches less than locations just miles away.Researchers who later studied the storm found that the area experienced a highly localized downslope wind off Rabbit Mountain, which kept the town a few degrees warmer than the rest of the area, and thus most of the precipitation fell as rain versus snow.CoCoRaHS founder, and Colorado State Climatologist Nolan Doesken said, "As the network continues to grow across Colorado and the Denver metro area, I'm sure we will learn many more interesting things about the local precipitation patterns."New volunteers can order a rain gauge and receive training online, or attend a local class to learn more. The next class is being offered at Denver Water on Saturday, Nov. 14 from 10 a.m. to 12 p.m.. Space is limited and an RSVP is required. Go to Cocorahs.org for more information.Below is map showing precipitation patterns around the Denver metro area as the storm moved in on Tuesday.If you are interested in becoming a CoCoRaHS volunteer and helping fill the gaps, click here to apply.To see storm totals in your area from the October storm click here.