National Weather Service United States Department of Commerce

Series of Pacific Northwest Storms; Wintry Mix in the Northeast and Parts of the Mid-Atlantic

A series of Pacific storm systems will cross the Northwest U.S. this week bringing gusty winds, high surf, periods of heavy rain, and mountain snow. Another storm system will continue sweeping through the Northeast and Mid-Atlantic Tuesday with a wintry mix of snow, sleet, and freezing rain making for hazardous travel. Read More >

About CoCoRaHS

 

The Community Collaborative Rain, Hail & Snow network (CoCoRaHS) is a community-based network of volunteers who report rain and snow observations from their own backyards. Reports are used by many people and organizations, including the National Weather Service. Additional rain and snow information from volunteer observers has been used to improve river forecasts or assessment of drought.

 

 

 

Graphic illustrating variability in precipitation. One photograph shows a narrow rain shower and how rainfall accumulations might change over short distances. Another photograph shows a narrow corridor of heavy snow and also how accumulations might vary.
 

Graphic illustrating variability in precipitation. Two maps show the difference between analyzed precipitation accumulations with when CoCoRaHS observations are available versus not available.

Precipitation can be highly variable over short distances. This was illustrated during a significant flash flood which occurred in Fort Collins, CO, in 1998. Researchers determined that the heaviest rainfall occurred away from official rain gauges, but some private rain gauges captured the heaviest rainfall. CoCoRaHS was formed after this event and has since spread across the country.

Learn more about the history of CoCoRaHS



Who Can Participate


CoCoRaHS is open to anyone with an interest in observing weather in their area. Volunteers report rain and snow information once per day in the morning (even if there was no accumulation) using a standardized 4-inch rain gauge. Time commitment is a few minutes a day. Volunteers purchase the rain gauge. Typical observations are rain accumulation and snow accumulation, but observers can also measure the liquid equivalent in snow cover and report hail size.

Click here for an application to join CoCoRaHS

Contact CoCoRaHS

 

Contact information for Illinois

Contact information for Indiana



Where are Volunteer Observers Needed?

 

Observations from additional CoCoRaHS observers would be helpful anywhere, but some parts of northeastern Illinois and northwestern Indiana have few precipitation observations. Of particular note, Boone, DeKalb, Ogle, Lee, Livingston, Ford, Newton, and Benton counties have 5 or fewer observers.

 

Map showing active CoCoRaHS observers in northeastern Illinois and northwestern Indiana as of March 2024. Counties with a very small number of observers are highlighted, including Boone, DeKalb, Ogle, Lee, Livingston, Ford, Newton, and Benton.