Saturday, April 12, 2014

Flood Threat Rising In Vermont, Surrounding Areas Now Through Wednesday

It's going to be a gorgeous April Saturday here in Vermont with sun and temperatures reaching the low 60s.  
Raging floodwaters crash through trees along
the Lamoille River in Cambridge, Vermont during
spring flooding in April, 2011. Similar scenes
are possible in Vermont, New York and New
Hampshire early next week. 

And that is the beginning of some problems.

Yes, I'm being a killjoy for going negative on some well deserved springlike weather, but today's warmth will help set the stage for what could be some fairly substantial flooding.

Most of the snow is gone from Vermont valley floors, but there's still quite a bit in the mountains.

It's been warm the past few days. Some snow has melted and rivers have risen.

That trend toward rising rivers will continue, starting today and continuing over the next few days as it gets warmer and warmer and rain enters the picture.

The National Weather Service in South Burlinton has got Vermont and northern New York under a flood watch through Wednesday.

It looks like any flooding this weekend won't be too serious. Just the usual low lying fields and low spots on local roads could go under water. But things could get much worse Monday and Tuesday, and maybe into Wednesday.

Here's what the flood watch says:

THE POTENTIAL FOR MORE SIGNIFICANT FLOODING WILL OCCUR IN THE

  MONDAY THROUGH WEDNESDAY TIME PERIOD ON MAINSTEM RIVERS AS
  WELL AS SMALLER RIVERS AND STREAMS. ANYONE LIVING NEAR THE
  LARGER MAINSTEM RIVERS MAY WANT TO THINK ABOUT TAKING
  PRECAUTIONARY ACTIONS THIS WEEKEND TO PREPARE FOR POTENTIALLY
  SIGNIFICANT FLOODING EARLY NEXT WEEK.

On Sunday, a warm front will cross Vermont, bringing some rain, especially to northern Vermont and much warm temperatures. Clouds and rain will hold temperatures in the 60s Sunday, but they won't fall much Sunday night.

Monday turns really, really warm, with readings well up into the 70s, possibly near 80 in much of Vermont, northern New York and a good chunk of the rest of northern New England. That will get the snow in the mountains melting super fast, and river water will rise accordingly.

Then a very slow moving cold front enters the picture. Little storms will ripple south to north along the front as it slowly drifts eastward across New York and New England. With a lot of moisture to work with the front and its parade of little storms has the potential to dump 1 to 2 inches of rain across the region.

Normally, two inches of rain wouldn't cause much of a flood worry. But by the time the rain arrives, rivers will probably be nearing or even already over flood stage.

So the stage is set for something that could definitely be worse than the usual springtime lowland flooding. At least moderate flooding is a good bet, which in some areas is high enough to damage some buildings.

The worst case scenario is flooding like that in the Lamoille River basin in Vermont in late April, 2011. Then, buildings were badly damaged in flooding in a stretch from Wolcott to Cambridge.  Such flooding could happen anywhere in Vermont, and parts of New York and New Hampshire by Tuesday.

Such damaging floods aren't guaranteed, but there's a chance. So if you're in a flood prone area, I'd spend the weekend taking precautions. If you can move stuff that would get damaged in a flood, I'd do it. An example might be some store owners in Montpelier, Vermont, which is along the Winooski River.

If you have backstock in your basements, I'd get those items to upper floors now. Homeowners in floodprone areas should get stuff out of the way too. And have a plan to get out of the way pronto in case the rivers rise.

Lake Champlain waters will rise, too, though don't look for a repeat of the 2011 record flood disaster. As of Friday, the lake level was at 97.7 feet, which is a little more than two feet below minor flood stage.

Flood stage is 100 feet, and the lake could reach that level as soon as the end of  next week. At 100 feet, there's minor flooding along the lake, with some low lying roads under water, a few shoreline parks get some flooding and there's often some minor shoreline erosion if it's windy.

My guess is Lake Champlain won't go into major flood territory unless there's a lot of heavy rain later in April and in May.

After the very wet cold front goes through Tuesday night, temperatures will crash. It will snow Tuesday night and Wednesday, and maybe pile up a few inches in the mountains. Valleys might even get a coating. But that won't last long. It's April, so readings will inch toward 50 degrees by the end of the week.

I'll caution again that a serious flood early next week is not certain. We could get lucky and get less rain than forecast, or maybe it won't get as warm as predictions indicate. Then things wouldn't be so bad.  Keep watching forecasts for updates on this one.

But better safe than sorry, right?

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