I had a great opportunity today to head over the local National Weather Service office in Burlington to chat hydrology with our local Service Hydrologist, Greg Hanson. I've met Greg many times before through various National Weather Service workshops and events they hold for the public and the media. But this time, I sought Greg out to learn more about our area rivers and streams and waterways and how they are impacted by flooding, and more importantly, how to forecast it!
We started off with a brief overview of our area rivers, which I'll inform you about before we go any further. There are 3 main water drainage basins across our local viewing area (northern NY, VT, and NH). Lake Champlain is the largest drainage basin, to which many of our area rivers run into. America's 6th largest lake, located on the border of NY and VT, serves as the drainage point to which several rivers run from the Adirondacks in New York, and much of western Vermont. Some of the rivers from the Adirondacks will also drain into the St Lawrence River, located at the border of northern NY and the province of Ontario. On the other side of our viewing region, is the Connecticut River. This river splits the border of Vermont and New Hampshire, and is our other major drainage route for eastern Vermont rivers and interior New Hampshire rivers. For Vermont, the divide is essentially, the Green Mountains, that "decides" which rivers drain where. Rivers east of the Greens generally drain into the CT River, and rivers to the west of the Greens mostly drain to Lake Champlain (with a few exceptions).
So, next, we discussed the quirks of all the area rivers across our region. And by quirks, I mean the "flood prone" areas. There are several areas within our local waterways that are more prone to flash flooding, or ice jam flooding. A few examples include the East Branch of the Ausable River in northern NY near Ausable Forks, The Great Chazy River at Perry Mills, the Missisquoi River near East Berkshire, and the Passumpsic River near Lyndonville just to name a few. There are several flood prone turns along our area river ways, both during warm season flooding (heavy rain events) or cold season (snowmelt and ice jams). They each pose challenges on how to forecast for such events.
In my blog tomorrow, I'll talk about how the weather service assesses local river levels and how to gage the threat for flooding before and during heavy rain/melting situations.