Warm Winter Benefit: So Far, Flooding Risk In Vermont Is Minimal

After weeks of cold weather, a rain storm and very warm
January thaw created ice jams that threw water and ice 
chunks across this road in Enosburg.  Because of the
warm winter we've had so far, similar scenes are 
very unlikely in the near future. 

Every other week in the winter and early spring, the National Weather Service office in South Burlington kindly gives us an update on how the late winter and spring flood risk is shaping up.

We got our first update last Thursday. If you hate damaging floods, and who doesn't, you're in luck, at least so far. The risk of winter and spring flooding at this point looks pretty low.  

A frequent flood risk in Vermont is ice jams on rivers that can form during thaws. The ice jams dam up the water behind it. If the jam is in the wrong place, a flood in a populated place could result. 

The wildest example is the 1992 ice jam flood in Montpelier which inundated the city's downtown.  

Sometimes, you can get ice jam floods in the middle of winter, courtesy of a January thaw. This was a big issue in January, 2018 after a frigid, often subzero period from mid-December, 2017 through the first week of January, 2018 froze Vermont river solid. And thick. 

Then, on January 12 of that year, temperatures rose to record setting levels near 60 degrees, with downpours. This broke up as snow melt and rain rushed into the rivers, and damaging ice jams result .  especially along parts of the Missisquoi and Lamoille rivers.

By contrast, so far this winter, it's been so warm there's basically no ice on Vermont rivers. No ice means no ice jams.  

There's still time for enough river ice to build up enough to create an eventual ice jam risk, but it will have to turn sharply colder.  So far, that kind of deep chill is not in the cards, at least for awhile.

Another big factor in late winter and spring flood risk is snow melt. Problem is, the snow has already melted in the weird late December and early January heat.  There's not much snow to dissolve if we see another big thaw.

Oh sure, we almost surely will receive more snow. Parts of Vermont received a little bit of it Friday and Saturday. But snowfall will need to be well above average for the next several weeks to get anywhere near normal amounts on the ground. 

At the time of their flood forecast last Thursday, the National Weather Service noted that Vermont rivers were running high due to recent rains, this doesn't mean a problem is developing. 

In fact, we're having some pretty dry weather until the end of the week. Rivers will recede.

Soil moisture and ground water is also wetter than normal. Lake Champlain is also a little higher than average for this time of year. 

But those are all artifacts of the late December and January thawing and rains.  For now, unless there is some big mega storm, we're safe from any real flooding for awhile. 

A lot can change between now and April, so it's always possible we could see some issues eventually. But for now, if you live in a flood prone area, you can relax.