Wednesday Evening Vermont Debby/Flood Outlook. Still Reasons To Worry

This afternoon's forecast track for what will then be
former Tropical Storm Debby has it centered right
over Burlington, Vermont at 2 am. Saturday. 

 The forecast trends on how Vermont fares with possible flooding from Tropical Storm Debby's anticipated remnants remain roughly the same. 

There's still plenty of cause for worry, and a few reasons for a bit of cautious optimism in some parts of the state. 

Maybe. 

CHAMBER OF COMMERCE APPROVED

Before we get into that, we should revel in what has been a rare for this summer Chamber of Commerce day we had in Vermont today. 

It was beautifully sunny, of course, with a scattering of fluffy clouds to make it all pretty. The sky was true blue, lacking the wildfire smoke that has been hazing up the atmosphere lately. Temperatures were totally comfortable, with highs in the 70s to around 80 in the warmest spots

Humidity was at rock bottom. If the dew point is in the 50s, that's regarding as comfortable. Dew points this afternoon across Vermont were in the  40s to near 50. Just delightful. 

Tonight will be clear and comfortable. Throw open those windows and let the fresh, cool air reinvigorate you and the air in your house. 

VERMONT DEBBY UPDATES

Now back to our regular Summer of '24 doom and gloom 

That westward trend in the forecasts for the expected path of Debby has stopped, and it is still forecast to go right over Vermont.  (Results may vary, it can still go a little west or a little east of us).

For what it's worth, the latest forecast from the National Hurricane Center puts what will then be former Tropical Storm Debby right smack dab over Burlington, Vermont at 2 a.m. Saturday.

This would still mean the heaviest rain might end up falling up in northwest Vermont and New York. That's not cast in stone, however. We still need to worry about possible flooding in many other parts of the Green Mountain State. 

Tropical Storm Debby, just off the coast of South
Carolina when this satellite photo was taken late
Wednesday afternoon, looks kind of 
disheveled, which is good if you don't want
a powerhouse tropical system menacing the East Coast.

The National Weather Service in South Burlington is holding off just a little while longer while meteorologists there await the latest guidance on whether and where to post flood watches. 

I would rate the chances of seeing a flood watch in at least parts of Vermont appear by tomorrow morning.

With Debby going overhead or just to our west, you'll notice the high humidity surge back in tomorrow night as the first wave of rain arrives. 

 The rain Thursday night will mostly serve to wet everything down pretty good. That's what will help set the stage for the flood potential. 

The westward path might allow breaks in the clouds to form during the day Friday. 

That could well only encourage more torrential thunderstorms to eventually break out, adding to a potential flash flood threat. Thunderstorms near tropical systems often have incredible rainfall rates. 

Often four inches per hour. Luckily none of those torrential storms will last anywhere close to an hour in any one place. But they'll still carry flash flood risks. Especially if a couple or few hit the same spot.

Friday will be a humid, unsettled, tropical day to say the least. 

A tropical storm or former tropical storm passing to the west of Vermont can create some gusty south or southeast winds, much like a winter storm passing to our west can cause those damaging downslope winds. 

I don't expect anything super damaging out of this, as Debby isn't - and won't be - and especially powerful system. But with wet ground, some trees could be prone to uprooting in gusty winds. Nothing widespread, and not nearly as big a threat as the possible floods, but it's something to keep in mind. 

Also - and this isn't in any official forecasts I've seen - the east side of tropical and former tropical systems, once they're inland, can produce tornadoes.  It will be interesting if we get the right conditions for a quick spinup with Debby.  I'll wait for further forecasts to see if that low but non-zero risk indeed develops. 

The heaviest rain looks to come through Friday night, so at this point I'd say the period from late Friday afternoon through Saturday morning is the most likely time to see flooding if we get it. 

Current forecasts give most of Vermont at least one to three inches of rain out of this, with locally higher amounts. 

If the predictions for somewhat lighter rain in eastern Vermont pan out, that's good for two reasons. The first is the soils in the Northeast Kingdom are sopping wet, and a couple sunny days before the storm won't cure that.  

So if less rain falls, that might minimize the flood risk. Again, maybe. IF the heaviest rain stays west. For what it's worth, some models I've seen show a slug or band of very heavy rain moving through north central and northeast Vermont overnight Friday and early Saturday, so those areas are NOT out of the woods yet. 

Another reason to hope the heaviest rain stays west would be to prevent torrents from falling in the headwaters of the Winooski, Lamoille and Mad Rivers.  It would lessen the chance of those waterways going over their banks again 

VAGUE OPTIMISM

My guard is still way up with this storm. I still definitely worry Debby could cause another huge mess in Vermont. But that scenario is still not guaranteed,. If there's no guarantee, there's a little hope 

One reason for a tiny smidge of optimism is Tropical Storm Debby, just off the South Carolina coast late this afternoon, is less organized than some forecasts indicated. So its remnants might be a bit less intense than they otherwise would be.

Debby's remnants will race through here much faster than forecasts were indicating a couple days ago. That gives it less time to dump bucket loads of rain on us.,

The system is now expected to move so fast that we have a shot at a Saturday with fairly decent weather. 

As for whether Vermont suffers big time again, or manages to dodge another bullet, we really won't know until this hits. 

Wednesday Evening Vermont Flood Update: So Far, Mostly So Good, But New Flash Flood Warning St. J/Lyndonville

Threatening clouds, but so far very little rain in St. 
Albans, Vermont so far today. Can't say the same for
some areas of the state that faced some pretty good 
downpours. Spotty flash flood risk lasts into the
evening, even though we've dodged a bullet so far.

UPDATE 7 PM

OK, bullet NOT dodged.

Just as I feared in my evening update an hour ago, enough rain has fallen in the Northeast Kingdom to prompt a flash flood warning.

The warning includes towns hit super hard yesterday, including St. Johnsbury and Lyndonville.

Up to two inches of rain has already fallen, and up to another 1.5 inches is anticipated soon.

The ground is so soggy and unstable there, that that amount of rain is more than enough so set off flash flooding.

So far, the flash flooding in the Northeast Kingdom doesn't appear to be as extreme as it was Tuesday. However, any added damage and trouble is just more misery for a Northeast Kingdom population that has already been through far too much. 

PREVIOUS DISCUSSION 

As of 6 p.m. this Wednesday evening all the flash flood warnings so far seem to be focused on New Hampshire.  Not good for them, but so far, Vermont has mostly dodged a bullet. 

However, a few more bullets might fly our way before the evening is over.  We'll still have to wait and see for the next few hours. 

Slow moving downpours are still crawling through the Green Mountain State. The risk of flash flooding is still there, especially in the Northeast Kingdom.

We have seen quite a few downpours around.  Very hit and miss, though. Some pinpoint places have received more than an inch of rain, while others, like here in St. Albans, had seen just a trace of rain and some rumbles of thunder through 6 p.m. 

The downpours that have limped southwest to northeast across Vermont have further "primed the pump" for possible local flash flooding if they get hit by more torrents of rain.  A flood advisory was hoisted this afternoon for parts of Bennington County, where one to two inches of rain fell in a short period of time. 

I'm noticing some pretty heavy rain has moved into Caledonia and Essex counties as of 6 p.m., so that will need to be watched closely. That's the zone that was so hard hit by Tuesday's floods. Which means even relatively brief downpours can set off more trouble and more damage. 

I'm also watching a heavy area of rain in eastern Addison County, which was moving quite slowly over steep terrain. That could cause trouble. 

Even though we haven't really had any major problems yet, the risk is probably peaking between now and about 9 p.m. as the day's rain - at least where it really poured - is beginning to add up. 

No guarantees we'll have flash flood problems. We might well get lucky.  But it's too soon to let your guard down. Let's wait and see what the next few hours bring.  

Wednesday Evening Vermont Storm Update: Winds Ramping Up, Still Questions On Snow, Mix

The latest snow forecast issued Wednesday afternoon
still features heavy snow of eight inches or more in
most elevations above 1,000 feet.  Patches of dry
air, and a possible increase in sleet could cut
accumulations some. High winds this evening
will create power outages, especially near
the western slopes of the Green Mountains. 

 An initial band of light snow, sleet and rain moved northward across Vermont this afternoon, depositing some light accumulations of snow in some of the high elevations. 

That's the opening salvo in our long awaited storm.

The Wind

The first high impact phase of the storm was just beginning as of 5 p.m. Behind that band of precipitation that passed through, a slot of dry air is moving in. Within that patch of dry air is the strongest winds. Especially west of the Green Mountains, 

So far today, I've seen gusts as high as 43 mph in Burlington, and I'm sure there's already been a few reports of wind a little stronger than that. I did see a report of a 49 mph gust in Janesville. 

As of 4:30 p.m., you could tell from VTOutages.org the strong winds had started in southwestern Vermont and were moving north.

At 4:30 p.m., about 1,800 homes and businesses were without power, mostly in Bennington and Rutland counties. That number of outages was increasing pretty fast. 

The Precipitation

The National Weather Service in South Burlington seemed like it was hedging its bets late Wednesday afternoon. 

The computer models still suggest Vermont will see a lot of snow, at least in elevations above 1,000 feet. But reading between the lines, experienced meteorologists have some skepticism. 

This sprawling system seems to be ingesting bits and pieces and areas of dry air, which could occasionally cut down on the rate at which snow, sleet and rain will fall tonight. 

It also seems like a layer of warmish air aloft will be a little more widespread and persistent overnight, especially in central and southern Vermont. That would create a better chance of more sleet, along with a bit of freezing rain and rain, and less snow.  

Still, the official forecast has six to 12 inches of snow piling up away from warmer valleys and mostly at elevations of 1,000 feet or more.   Most places in the Champlain Valley, lower Connecticut Valley and lowlands around Route 7 between Brandon and Bennington should stay under six inches. A few mountain summits could make it to two feet of new snow. 

Plan on crappy road conditions statewide for the Thursday morning commute, but results will vary.  Some places might be just slushy, others could be very snowy, with very low visibility in snow and possible blowing snow. Especially at higher elevations. 

High elevation Route 9 in Marlboro was already 
starting to get slushy as of 4:30 this afternoon as the 
initial patches of snow and mixed 
precipitation began making their way through Vermont. 

Precipitation rates will lessen during the day Thursday. But depending on where you are, it will still be either a solidly snowy or slushy day.  Warm spots go above freezing during the day, but not by much. 

That will make any measurements of snow tricky.  Elevated and grassy surfaces might continue to collect snow, but pavement and plain dirt might see more melting. We'll see. Higher elevations should see a continued, gradual accumulation of fresh snow all day. 

A wild card is whether wet snow will accumulate fast enough on trees and power lines to trigger additional power outages. The winds will be much lighter during the day Thursday than they will be overnight, but snow might interfere with crews trying to restore power.  

The Wind Down.

It still looks like this whole thing will ever is slowly diminish with time from Thursday night through Saturday. Snow and valley rain showers during the days will become lighter and lighter and more and more scattered.

There might even be a hint or two of sun on Saturday, and if we're lucky a fair amount of sun Sunday. 

Temperatures will slowly climb out of the rut we'll be in tomorrow. Valley highs on Thursday will be between 30 and 38; then 34 to 42 or so Friday, perhaps 38 to 46 Saturday and in the upper 40s Sunday.

I'm waiting for the other shoe to drop and ruin it, but forecasters are still calling for partly to mostly sunny skies when the eclipse hits Monday afternoon.  

Wednesday Evening Update Vermont Winter Is Back, Slight Increase In Snow Prediction

Still an amazing amount of open, ice-free water on 
Lake Champlains as of today, and remarkably little snow
on shore.  We are going to get a few inches of snow,
and subfreezing temperatures over the next few days
might manufacture a little more lake ice. 

It really was kind of a classic February winter day in Vermont today, which is a huge change from what we experienced this month so far.  

True, there's much less snow on the ground than there usually is this time of year. But at least the ground is white. For many of us, Wednesday was the first time this we had a snow cover since late January. 

The day also turned brighter and brighter and less cloudy - as expected - after the early morning's snow. The day featured that classic February light. A blue, cold light, but at a higher, friendlier sun angle than the dark depths of winter in December and January. 

Next up, we'll see another, bigger snowfall. More on that in a bit.

TODAY'S SNOW

But first, we'll take a final look at last night's snow. It wasn't much, but it still over-performed a little. The western slopes of the central and northern Green Mountains did the best, with three to five inches of fluff from Tuesday morning's little snow dump. Most other places had one or two inches, that's about it. 

Overall Vermont snow depth remains scant.  Even in the rather high elevation snow belt towns of Shrewsbury and Greensboro, there's only a foot of snow on the ground. Most everyone in Vermont still had six inches or less on the ground as of Tuesday morning.

The snow that fell early Wednesday had very little water in it - you could tell by how light and fluffy it was if you swept it off your sidewalk or driveway this morning.  Most places received less than a tenth of an inch of liquid water equivalent. A few places along the western slopes of the Green Mountains had between a 0.1 inches and 0.2 inches. 

NEXT SNOW

The National Weather Service has slightly increased the
amount of snow we can expect Thursday night and early
Friday, though as you can see, this isn't going to be
any kind of blockbusters snowstorm. 

The National Weather Service has slightly increased amount of snow due from the next snowfall, which is due mostly Thursday night. 

 Depending on where you are in Vermont, it will be the biggest snowstorm since either January 16 or January 7.  But that's not saying much at all. 

Generally, we're expecting about 2.5 to 5.5 inches of snow, with locally higher amounts in the Green Mountains. 

This will be a pretty low impact snowstorm, though calling it a snowstorm is really pushing it.  First of all the timing is good. The snow will pretty much move in after Thursday evening's commute. The heaviest  snow will have ended by Friday morning's commute. 

But lingering snow on the roads and remaining light snow falling from the sky will slow things down a bit. 

With that in mind, there is a winter weather advisory for the Green Mountains and a good chunk of the rest of northern Vermont overnight Thursday through Friday morning. Unlike the storm that ended up passing well to the south of us Monday, the forecasts for this snow event are much more consistent.

There's not much uncertainty in the forecast, so I have a pretty high confidence that we'll get what's forecast. I really hope I don't get burned enough to make me look like a fool for saying that, but I think we're good. 

Much like the light stuff we got early this morning, the snow we get Thursday night will be fluffy and airy. Easy to plow, easy to clear, not anything that will linger on the roads much. Temperatures will stay near 20 degrees Thursday night and rise into the upper 20s Friday. That's more than sufficient for road salt to work.

LOOKING AHEAD

Longer range forecasts have really backed away from the idea that most of the central and eastern part of the United States would be a little cooler than average through the end of February. 

Instead, following the pattern of the entire winter, most of the nation is now looking on the warm side through the end of the month. 

For us here in Vermont, it's so far looking like we'll miss out on most of that warmth, which will probably be centered around the middle of the nation. These forecasts are hinting at temperatures fairly close to average here in Vermont between now and Leap Day, February 29.

We'll see frequent small weather disturbances Friday through pretty much all of next week. That means we'll often see periods of light snow and flurries. 

There are some hints that we might finally have a brief shot at subzero weather for the first time this winter around Feb 24-25, but that's really iffy, to be honest.

By the way, now that we're into the middle of February, whatever is considered normal temperatures will now start to gradually creep upward. 

After Valentine's Day, the chances of super cold Arctic outbreaks generally begin to diminish. Though it can get below zero all the way to the end of March.  

I usually say in mid-February that the worst of winter is about over, but we are still waiting for whatever "worst" is.  A strange winter indeed!