Saturday, April 20, 2019

So Far, Vermont Flooding Mostly Minor In Vermont; But Water Continuing To Rise

State of the flooding in the region as of 7:15 this Saturday morning.
Light green areas are flood warnings, meaning flooding is occuring.
Dark green is flood watches. I do think we'll see a few more
light green flood warning areas popping up during the day today. 
As expected, rivers were rising across much of Vermont and surrounding areas early this Saturday morning. Already a few flood warnings were up in northern parts of the state.

With continued warm temperatures in at least some of the mountains and another surge of rain to go, flooding will probably still worsen in the state.

Rainfall across northern areas overnight ranged from a quarter inch to an inch. Normally that wouldn't be a big deal, but with snow melting from the mountains and saturated ground, this was enough to create at least a little flooding.

Snow melt from the mountains is pretty healthy. The top of Mount Mansfield lost eight inches of snow Friday, leaving the snow depth at 99 inches. That's still a lot, but it's the first time they've been under 100 inches since mid-February.

So far, things aren't as bad as they were with Monday's flood, but there's still areas of concerns. Parts of the Passumpsic, Missisquoi and Lamoille rivers in northern Vermont were already under flood warnings at dawn today. Route 122 near Route 5 in Lyndonville was already shut down by high water. So is part of Route 5 in St. Johnsbury Center.

In New York, flood warnings were up along the Ausable River. Flood warnings were also in effect on some northern New Hampshire rivers.

We'll have to follow rain patterns today to see if the situation intensifies. In general, the low areas that usually get flooded in the spring will go under water. As always, avoid driving through floodwater. Turn around and find another way to get to where you're going.

Forecast map has the Missiquoi River at North Troy flirting with moderate
flood stage today. 
Early this morning, a stalled out cold front bisected Vermont, roughly from between Bennington and Rutland, to a little southeast of Montpelier, to a little northwest of St. Johnsbury.

South and east of that line, it's summery humid with temperatures in the 60s. North and west of that front, it's a dank April morning with temperatures in the 40s.

If you have a sharp temperature contrast like that, you do have to worry about heavy rains.
Moisture pools along such boundaries and the contrast helps add lift to the atmosphere.

As it was, with the front stalled across north central Vermont overnight, some of the heaviest rain fell right along this boundary, with about an inch reported.

A batch of steadier rain from overnight was heading northeastward out of Vermont and into central and northern Maine, where flood concerns are even bigger than they are in Green Mountain State.

Meanwhile a batch of heavy showers and thunderstorms was entering southern Vermont as of mid-morning. It's unclear exactly how far north this rain will get before it gets shunted east. But much of the state can expect more showers, a few of them heavy, on and off during much of today.  It's also unclear if this northward moving batch of rain will lighten up, or maintain its intensity. 

Nevertheless, the rain and storms will generally want to follow that stalled front, so chances are at least southern and central and eastern Vermont, if not the whole state, could get another good, unwelcome dousing today.

In the warmer air in eastern Vermont, there's a heightened chance this rain could develop into heavier downpour-ish thunderstorms. That could increase the flash flood risk over the eastern half of the state.  Forecasters will just have to track it and see what happens.

Since there are some thunderstorms mixed in, there's the risk of torrential downpours that could touch of flash flooding in a few spots.

Rain will taper off this evening.  Easter Sunday still looks nice, with partly sunny skies, warm temperatures and only a minimal risk of showers.

Although there looks like there will be unsettled, showery weather of and on next week, the rain doesn't look particularly heavy, which is good.

Runoff from today's rain and snowmelt and continued runoff from some rain will continue to flow into Lake Champlain. It'll reach its 100-foot flood stage as soon as today.

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