Tuesday Evening Vermont Forecast Update : News Is Bad, Flood Prospects Worsen, Unfortunately

Flash flood risk has been upgraded to "moderate" in
much of Vermont and surrounding areas, which
makes at least some flash flooding pretty 
much guaranteed, with possible serious damage.

 The forecasts for tomorrow and tomorrow night's flood risk have gotten noticeably worse over the course of today. 

The relative certainty of the event has increased. So has the expected rainfall amounts. Which means the flash flooding could end up being quite extensive here in the Green Mountain State.

This still won't be as bad or as long lasting as the cataclysmic flooding we saw exactly a year ago. But it will still be dangerous, damaging, even life-threatening in some areas.

Take this one seriously.

To nobody's surprise, the National Weather Service has issued a flood watch for all of Vermont except for our two southernmost counties, where rainfall should be lighter. The flood watch is in effect from 11 a.m. tomorrow through 11 a.m. Thursday. 

Flood watches are also up for northeastern New York, most of New Hampshire and western Maine.  

Let's break it all down:

TODAY/THIS EVENING

As expected, scattered thunderstorms erupted this afternoon around Vermont, and will continue into the evening before sputtering out. 

Some of the most torrential thunderstorms hit central Vermont, along roughly a line from north of Middlebury, to near Montpelier and on toward St. Johnsbury. Some of these dumped a good inch of rain. 

That's precisely the area that saw the heaviest downpours in last Saturday's round of thunderstorms.  And it's the band across Vermont that could well see the heaviest rain from this upcoming flash flood episode. 

So this piece is really bad. 

WEDNESDAY

When you get up tomorrow morning, it won't seem so ominous. Sure, it will be incredibly humid. But there won't be much rain around. 

That will change during the afternoon. As meteorologist Tyler Jankowski of WPTZ explained, a warm front associated with the remnants of Hurricane and Beryl will be trying to ever so slowly lift northward toward central Vermont.

At the same time, a weak cold front will try to move due south in Quebec. That puts central and northern Vermont between the two fronts.  Between those two fronts, Beryl, with an assist from the Atlantic  Ocean and the Gulf of Mexico, will provide  the necessary water for torrential downpours. 

The two fronts will conspire to make the air rise, so the downpours will break out, and pretty much keep running west to east between those two fronts. 

As of this evening, the forecast for the heaviest rain runs from that Middlebury/Montpelier/St Johnsbury line. Which of course is the exact worst place it could be. We're talking three to six inches of rain in less than 15 hours. 

That's enough to trigger some pretty damaging and dangerous flash flooding. 

It's still quite possible the heaviest west to east band of flooding rains could set up a little north or a little south of the area I outlined. If that happens the flash flooding will be pretty much as bad as what I outlined, but it would of course be far northern Vermont or south central Vermont. 

We'll see updates and adjustments tomorrow morning, I'm sure. 

NOAA's Storm Prediction Center has upgraded its flash flood risk from slight to moderate across tomorrow for northeastern New York, the northern two-thirds of Vermont and northern New Hampshire. 

That risk level almost guarantees there will be some reports of fairly substantial flash flooding. Again, not as bad as July 10, 2023, but bad enough. 

The timing of this worries me, too. Flash flooding would probably start in earnest by late afternoon or evening. But it will likely peak after dark.   

As if we don't have enough to worry about with
flooding Wednesday, there's a low but 
definitely not zero chance of a tornado or two
across New York and southern and central Vermont.

Flash flooding and severe storms are more dangerous at night. If you're driving at night,  you might not see the road under water or washed completely away until you hit it. 

People in homes might not have a good read on how the water is behaving at night. And a hasty evacuation is dangerous in the dark. 

Oh, and we have yet another potentially dangerous problem to deal with tomorrow. Former tropical storms are famous for spinning off tornadoes. Beryl created a couple dozen tornadoes in Texas, Louisiana and Arkansas yesterday.

Along and south of that warm front I mentioned, winds will change directions with height. So southern and possibly central Vermont is at risk for a few rotating thunderstorms. The biggest risk from these is damaging straight line winds. But we might also see a brief tornado tomorrow, especially from about Route 4 south. 

Also, although far southern Vermont is outside the greatest flood risk area, thunderstorms could become intense enough to produce some instances of local flash floods. 

THURSDAY

The heavy downpours will have departed by the time dawn breaks Thursday. Then we'll have to shift attention to the main stem rivers. 

Some of them will go into flood stage, but it continues to look like rivers like the Winooski and Lamoille won't get nearly as high as they did in last year's epic disaster.  Tuesday evening forecasts call for both rivers to stay below flood stage. I think future forecasts will increase the flood risk along those two rivers, but we should still fall far short of the horrors we saw in the Winooski and Lamoille valleys last July. 

I think downtown Montpelier is safe, unless the forecast turns much, much worse. I think downtown Johnson should mostly escape trouble, again, fingers crossed. 

WHAT TO DO

If you live in an area prone to flash floods that could force you to evacuate, put together a to-go bag tonight or early tomorrow. Include important documents, medications and other necessities. Think about what hoops you'd have to jump through to get your pets or elderly relatives out of harm's way. 

Flash floods happen, well, in a flash, so you need to be nimble. Have ways to get weather warnings and advisories. 

If you're told to evacuate by emergency officials, do it. And quickly. If they close a road, don't go around the barriers. If you can help it, don't wade into floodwaters. It's probably polluted and could get you sick. 

If your basement is filling up with water, don't go down there. Basement walls and foundations are famous for collapsing in flash floods. That can trap you under water under debris if you're down there.  

Charge your devices tomorrow morning. We could have power outages. Remember, there could be damaging thunderstorm winds in central and southern Vermont, or even a brief twister. Make sure you're ready to take shelter in a sturdy building if the National Weather Service issues a severe thunderstorm or tornado warning. 

You want to be wicked careful driving. Please do NOT drive through flooded roads. You could stall or get swept away in just several inches of water. Also, the road might no longer be there under the water. It might have washed away. 

BOTTOM LINE

This is yet another depressing "here we go again" moment. We have to face the reality that climate change has made weather extremes more likely. 

I guess we've already had a lot of practice with this sort of thing. The main goal here is to prevent loss of life.

We are a bit at the mercy of this thing, although Vermont has taken steps to become more flood and disaster resistant. 

Don't panic, but be sober.  This too shall pass, and we'll have a breather again soon enough. 

Ack! Measurable First Snowfall Of Season Now Forecast For Vermont This Week

Time to bring back the National Weather Service snowfall
prediction map!  The NWS in South Burlington is now
predicting an inch or two of snow in the Champlain 
Valley on Wednesday, two to six inches in much'
of the rest of Vermont, and more than six inches 
up in the mountains. This forecast will probably
shift some before the actual event.

 A few snow flurries late yesterday and overnight finally ended Burlington's long snow free streak.

The trace of snow in Burlington reported Sunday was the latest first flurry of the season since November 16, 2007. It was also the first flurry since April 28. 

Now, in a bit of a surprise shift in the forecast, it's beginning to appear that we will have our first significant snowfall of the season on Wednesday.

By "significant," I don't mean a blizzard with several feet of snow. But it's beginning to look like the warm Banana Belt of the Champlain Valley will see more than an inch of snow at least. Maybe two inches. 

Much of the rest of the Vermont has the potential for two to six inches of snow. The mountains could see six or more inches, according to the National Weather Service in South Burlington.

This is a big shift from previous forecasts.  It's also not a guarantee yet. It's also possible the valleys will still remain warm enough to that there won't be much snow. But the forecast is trending whiter. 

It was thought that a weak storm would head well off the coast, so deeper moisture would miss us, leaving us with light precipitation. An even weaker storm to our west would keep the air just warm enough so that snow would be insignificant, and mixed with rain in the valleys. 

That idea has gone out the window. 

It looks like the coastal storm, while still not a huge nor'easter, will come close enough to give us enough moisture for a consistent period of precipitation on Wednesday.  And that day is looking a little colder than first thought. 

That's a recipe for snow. 

This idea of a small snowstorm Wednesday isn't cast in stone just yet. Just slightly warmer than expected temperatures or a slight shift in storm track can mean the difference between a few inches of snow and nothing. 

Even if the current forecast is 100 percent spot on, this won't be a blockbuster storm by any stretch of the imagination. But it will be the first one of the season. My experience - and probably yours - is that the first snow is especially chaotic in Vermont, even if it isn't a huge dump.

People "forgot" how to drive in the snow. Snow tires aren't on vehicles yet. Expect people to be nuts on the road Wednesday, so start now planning on giving yourself extra time if you have to go anywhere, or better yet, stay home if you can. 

It will stay cold, so any snow we do receive won't melt in a big hurry. 

By the way, that trace of snow in Burlington Sunday evening was almost a month later than average, as we can usually expect the first flurry of the season around October 15.

However, if Burlington receives an inch of snow on Wednesday, that'll be right about on schedule. Wednesday is the 16ths, and the average first inch of the season is on November 17.

Today's Iffy Vermont Severe Weather Forecast

Forecasts for severe weather haven't changed much from
yesterday. Slight chance of severe storms in yellow,
just a marginal, slight chance in dark green. 

UPDATE 1 PM FRIDAY

Things so far seem to be playing out as expected, with the worst of the scattered storms today appearing to target central and southern Vermont, along with much of central and southwestern New England, with parts of New Hampshire and Maine getting in on the act.

NOAA's Storm Prediction Center said they'd likely issue a severe thunderstorm watch for an area encompassing most of southern New England, the southeastern half of Vermont and large swaths of New Hampshire and Maine. 

Giving hints to what might be to come, a fairly strong line of storms went through southern and central Vermont late this morning and early this afternoon.

One storm has prompted a severe thunderstorm warning around White River Junction. The National Weather Service said the storm could generate strong, damaging winds.

Radar imagery indicated that storm was rotating, but so far not enough to produce any kind of spin up tornado. 

Another severe thunderstorm warning for winds of up to 60 mph just went up for Bennington County as of this writing, 12:50 p.m. 

Other lines and clusters of storms should form this afternoon and move west to east across Vermont. The air, as expected, is more stable in northern Vermont, so if any severe storms develop there, they'd be very few and far between. 

Up north, you might get lightning and some downpours, but I'm not overly bullish on much north of a Middlebury to Wells River line. However, I did notice at 12:55 a rapidly developing line of storms over northeastern New York, probably heading toward Franklin County, Vermont. 

PREVIOUS DISCUSSION

There might or might not be severe storms in Vermont today. 

Chances are at least a few towns will get slammed by strong, possibly damaging winds, but the question is, how widespread will this be?  

Working in favor of storms are some fairly strong winds aloft, which also change direction with height. 

We expect a fairly good contrast between warm temperatures near the surface and much cooler readings aloft. That helps thunderstorms develop. 

The timing of an approaching cold front is pretty good, too. It'll come through this evening, giving a chance for strong storms to form ahead of the front.  

Clouds and rain this morning could, maybe, stymie some of the storms this afternoon.  A warm front was lifting through Vermont early this morning, accompanied by lots of showers and maybe some rumbles of thunder. 

If these showers don't move out fast enough, or leave lots of debris clouds behind overhead, that would limit, but not stop the severe weather threat. But if some sun can come out in the increasingly humid air today, that would boost the chances of strong to severe storms. 

With all that said, the forecast hasn't changed much from yesterday. The best chance of seeing some severe storms this afternoon are south of Route 2. The biggest threat would be from damaging wind gusts. Most of Vermont is still under slight risk of severe storms, level two of five in the threat scale. 

We still have a very, very, very low, but not zero chance of a brief spin up tornado. That's if any supercells can form out ahead of any lines of storms that develop. 

In the end, we'll probably wind up with a handful of reports of wind damage in a few towns in Vermont. Of course, it's impossible to tell in advance which towns. I don't think there will be any real trouble with local flash floods. The rain will come down torrentially with some of these storms. But, they will be moving right along, so it probably won't rain enough in any one spot to trigger trouble. 

You'll just have to pay attention to the skies and any warnings the National Weather Service might issue. Be ready to duck into a sturdy building at any time this afternoon and evening if you see dark clouds approach, hear thunder or receive a warning or special weather statement. 

It's not a good day to go out on the lake or take a hike. You can do that during this weekend, when the weather is going to be absolutely gorgeous. Instead, stay close to places where you can shelter from a storm. 

Saturday will actually be a bit on the cool side. It is almost September after all. Most of us will stay in the low to mid 70s under sunny skies.  The sun will continue all day Sunday, but you'll notice it warming up again. 

After a brief spell of very warm and humid weather (Again!) early in the week, it looks like it will turn cool again. We're almost ready to put a fork in summer. 

Christmas 2020: Strong Winds, Flood Risk And A Flash Freeze

One model run for early Christmas morning shows
a sharp cold front in western Vermont. Low 50s from the
Greens east, upper 20s far west. Timing of the cold front
and its intensity are still in question.

Details are slowly coming together on an expected nasty Christmas Eve and Christmas Day storm here in Vermont and the rest of the Northeast, but timing questions are huge.  

Note The automated ads associated with this blog post might be a little out of control today. If so, please be patient and scroll down to keep reading. 

Forecasters are pretty sure we're in for a good dousing of rain, some strong, potentially damaging winds and something known as a flash freeze, which I'll get into in just a bit. 

 There will probably be some snow with this, too, but just how much is really up in the air.  

Here's what's going on: A parade of storms has been smacking into the Pacific Northwest, dumping a lot of rain out that way, which is pretty typical for winter.  

These storms, most of them in somewhat weakened and definitely dried out form, are eventually zipping through New England with little fanfare, just some light precipitation. 

One came through yesterday, another goes by a little to our south tonight and tomorrow, no big deal. 

However, one of these Pacific storms has a lot of energy with it.  Plus, a deep dip in the jet stream will form as this storm gets going.  

This will allow deep subtropical and warm air to fly north on strong upper level winds ahead of the storm's cold front.

This will unleash what looks like quite a bit of rain on us Christmas Eve day and night. Storm totals could easily go over an inch. 

That deep snow in southern Vermont will rapidly melt with the warmth and rain.  Flooding is definitely a possibility.  

Already, some river forecasting models depict some flooding along the Otter Creek and Mad River, and it's likely most other rivers will rise. 

Most of the trouble with this thaw and rain will most likely be small stream, street and basement flooding. This would literally put a damper on Christmas celebrations, already seriously cut back due to Covid. 

Remember those strong upper level winds I just mentioned that are bringing that warm, wet air to us?  Some of those winds could mix down to the surface, though it's unclear to what extent that will happen.

The rapidly diminishing snow cover in southern Vermont might, just might help create a temperature inversion that would help keep the strongest winds from reaching the surface. But we're not sure.

At this point, the western slopes of the Green Mountains and the Champlain Valley have the best chance of getting slapped by strong, potentially damaging wind gusts. This would be mostly a tree and power line issue. Again, something you don't want to have at Christmastime. 

We could see temperatures get well into the 50s Christmas Eve night. That would get us close to record highs most days this time of year. Except Christmas Eve is the anniversary of a bonkers 2015 holiday heat wave that brought Vermont temperatures as high as 70 degrees. So no record highs that day. 

I suppose there could be readings close to record highs for Christmas Day in the early morning before temperatures fall.

Incredibly, what seemed like a lock for a white Christmas in southern Vermont, which got two to three feet of snow in many areas last week, now looks questionable.  That will depend on the timing of the storm's cold front. 

The cold front on Christmas Day looks to be a real humdinger. I picture a line of heavy downpours just ahead of it, followed abruptly by crashing temperatures and a changeover to snow.

This is that flash freeze I referred to.  All that water from the rain will instantly freeze on roads and sidewalks, presenting a hazard to anyone driving or walking. 

The rain will change to snow with the passing of the front.  It's unclear how much snow will fall, as forecasts are all over the place. It depends mostly upon the timing and strength of a new storm riding northward along this strong cold front. 

Computer models are all over the place, because they don't have a handle on the situation yet. According to this morning's forecast discussion from the National Weather Service in South Burlington, one model has Burlington receiving somewhere between a half inch and 18 inches of new snow on Christmas Day.

I'm guessing the low end of that range, but that's just a guess right now. 

The timing of the powerful cold front is a question mark, too.  It could enter western Vermont before dawn and sweep right through, or it could wait until during the day.  Which means right now, it's impossible to know what conditions will be like when you wake up Christmas morning.  It could be in the 50s and raining, it could be way below freezing with snow and blowing snow outdoors.

Again, the models are all over the place.  One run of computer models has the temperature in Burlington at around dawn somewhere between the upper single numbers to low 50s. Yeah, no help there. 

Whatever happens, the wind will continue to crank as temperatures fall during Christmas Day.  

We might not yet know the timing or the intensity of this year's Christmas storm. It's 2020, after all, anything can happen.

Just plan on rough weather outdoors.  It will be yet another good excuse to heed the warnings of the Vermont Health Department to just stay home with your immediate family and not venture out to somebody else's house. 

This would prevent the spread of Covid, and also prevent you from getting trapped or in a crash on bad, icy or flooded roads.