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Weather, Climate, and Community

Exploring rainfall on the peninsula

by JACKSON PARR, Wisconsin Sea Grant

When people think of water in Door County, they mostly think of the 300 miles of Green Bay and Lake Michigan coastline that contribute to so many of the region’s vital industries. Other people may think of karst bedrock and the challenges it creates for groundwater contamination. More people should think about rainfall. 

Wisconsin Sea Grant is partnering with the Door County Land Trust and the Climate Change Coalition of Door County for an event focused on rainfall. The event, “Weather, Climate, and Community,” will focus on rainfall trends in Door County, why they matter, and how to get more involved in the science behind it all. 

My interest as a Flood Resilience Fellow at Wisconsin Sea Grant is to think about rainfall from an extreme weather and disaster preparedness perspective.

The frequency and severity of rainfall is increasing across the United States, including Door County. Although the peninsula has largely dodged the historic 100-year events – at least according to the single long-term rain gauge in the county, which lives a few miles north of Sturgeon Bay – the number of 2-inch rain events each year is increasing (as shown in the accompanying graph). Those 2-inch rain events should happen just once every year, but in the past decade there has been nearly twice as many as predicted. That amount of rain is not going to wash a beachfront home into the bay, but it could affect mobility of vehicles more frequently. 

Those moderately intense rain events also interact with lake levels to create a combined flood hazard. Studies in Green Bay’s East River demonstrated that high lake levels, such as those seen around 2020, can back up water that would otherwise flow into the bay and create upstream flood hazards. 

This figure shows the number of 2-inch rain events in Door County each year since 1905. The trend line suggests an increasing frequency of these events, and the highest frequency of these events took place in the most recent decade.

Jeff Lutsey’s interest in rainfall at the Climate Change Coalition of Door County is to support the Door County Big Plant, the annual spring event where volunteers collectively plant thousands of trees. In many cases, those trees are planted in remote areas that are only accessible on foot. That means in dry years, hauling water to the young, thirsty trees is very resource intensive. Getting better information on where it rained and how much, can allow Lutsey to better allocate those resources to areas on the peninsula of greater need. 

To do that, we’re taking advantage of the Community Collaborative Rain, Hail and Snow Network (CoCoRaHS) to get a clearer picture of rainfall on the peninsula. CoCoRaHS is a national weather monitoring network of volunteers that use rain gauges to check rainfall amounts and submit that data to the national database. By adding additional volunteer monitors across the peninsula, we’re able to see differences in rainfall between Gills Rock, Jacksonport and Algoma. 

At “Weather, Climate, and Community,” you can learn how to participate in the CoCoRaHS system, and there will also be a limited number of free rain gauges available for you to install at your property. 

During the event, I will share the findings of a Flood Vulnerability Analysis conducted for Door County, including precipitation trends and projects. Lutsey will review the 2024 Door County Big Plant and how you can get more involved, and Paige Witek of the Door County Land Trust will talk about the importance of citizen science and how the organization supports that. 

The event will also feature a virtual presentation from Natalie Chin and Austin Holland, members of the Wisconsin Initiative on Climate Change Impacts (WICCI) Tourism and Outdoor Recreation Working Group on the impacts of climate change on the tourism and outdoor recreation industries of the state.

The public is invited and attendance is free for “Weather, Climate, and Community” Thursday, May 16, 6-7pm in the Sevastopol School Pioneer Room, 4550 state Highway 57.