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| The National Weather Servide in South Burlington has this prediction for heavy rains with the upcoming storm. Green areas should see at least an inch of rain. Yellow aeras will more likely get 1.5 inches of rain or more. A few spots might get two inches. Flood watches are in effect. |
The National Weather Service in South Burlington, Vermont has gone ahead and issued a flood watch for the entire area. It runs from late Thursday night into Saturday afternoon.
That warm storm that's coming is destined to dump perhaps an inch of rain or more on us before a "dry slot" temporarily reduces rainfall rates. (See the discussion below about the dry slot.)
Temperatures will warm into the 50s in many locations Friday afternoon and night. (We might see a couple of record high temperatures out of this, we'll see.) The warmth could melt much of the snow cover in the hills and mountains which is unusually thick and heavy for this early in the season.
The result will be definite rises on all the rivers in and around Vermont. It's a little uncertain still how much snow will melt. But we could see the equivalent of two or three inches of rain come off the mountains in the form of melted snow, plus the inch or so of rain.
That could be enough to set off flooding.
This won't be a blockbuster flood. Don't expect Irene the Second. But any flooding needs to be taken seriously. If the road ahead of you is flooded, don't drive through. You don't know how deep the water is, and you don't know if the roadway washed away.
I don't anticipate a lot of evacuations due to flooding, but if they tell you to get out, then get out. Winter flooding is particularly dangerous because the water is so cold. And it's pretty much always night around the Winter Solstice, which means it's harder to see flood waters creeping up around you.
It still looks like some freezing rain will be in there at the start Thursday night. That's most likely in the Northeast Kingdom and the northern tip of New York. Roads might be icy late Thursday night and early Friday morning in those areas.
Get ready for gusty winds, too. A lot of us will see wind gusts in the 40 to 50 mph range with this storm, especially along the western slopes of the Green Mountains. A few power failures might result
PREVIOUS DISCUSSION:
A lot of people are probably bummed that the storm coming in for Friday and Saturday around the Northeast will bring mostly rain, even to northern New England.
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| Jammed up ice on the Missisquoi River near Enosburg last January. Although nothing this bad is expected with the upcoming warm storm, expect some ice movement and rises in Vermont rivers over the weekend. |
It's right before Christmas, and people expect snow, right?
However, it's probably a good thing in the grand scheme of things that this storm doesn't have a lot of cold air to tap into.
That would just make what will be a powerhouse of a storm much, much worse if there were cold air to clash with the storm's warm side.
Storms tend to be stronger when there is a very deep, sharp dip in the jet stream. They're even stronger when the dip in the jet stream is tilted a bit, so it runs northwest to southeast, instead of straight north to south, or northeast to southwest.
This storm will have those ingredients. Which means pretty much everybody from Florida to Quebec will see areas of strong winds, heavy rain, and thunderstorms. In parts of the Southeast, some of the storms will probably be severe.
In fact, Florida in particular had better watch it. A lot of energy in the atmosphere is sinking south deep toward the Sunshine State. There's a real chance of some tornadoes there Thursday. Those twisters may extend up into far eastern North Carolina Thursday night.
Even up here in Vermont, there's the possibility of a rumble of thunder during this, though there will certainly be no severe thunderstorms.
This storm will also create some odd temperature arrangements. High temperatures on Friday could well be just about the same in Tallahassee, Florida and Burlington, Vermont - in the 50s.
Because of the orientation of that dip in the jet stream, the storm will zoom directly northward from around Georgia late Thursday night to somewhere near Ottawa, Canada late Friday night.
There are already flood watches up for parts of the already soggy Mid-Atlantic states.
Back to Vermont: We know it's going to rain and get windy and warm with this storm, but some of the particulars are still big question marks. Very often when a big storm gets wrapped up like this one looks like it will, it can create something called a dry slot. It's just a tongue of dry air that gets wrapped into the circulation of a storm from the southwest.
This can shut off precipitation, or at least reduce it. But it can increase mixing in the air, which can lead to both strong wind gusts and, briefly, unexpectedly warm temperatures. There is the risk of some downslope winds along the western slopes of the Green Mountains on Friday. Some of the wind could be strong enough to knock down some trees, branches and power lines.
If enough warm air mixes in, there's a chance temperatures in some valleys in western Vermont could approach 60 degrees.
Nobody is sure exactly where and when this dry slot will set up, hence the question marks.
What with the expected rain, and snowmelt, rivers will rise and ice will move around, so there's the risk of some localized flooding. At this point it doesn't look like it will be anything extensive, but it will be something to keep an eye on nonetheless.
Behind the storm, cooler air will filter in Saturday and Sunday, but this won't be a big blast of Arctic air.
Instead, daytime temperatures will fall to near normal readings in the mid 20s to low 30s Sunday through Christmas. Although there might be some snow showers Saturday night and Sunday, they won't amount to much. Some areas of Vermont will not see any measurable snow, so many valley locations will not have a white Christmas, at least as it looks now
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