UPDATE 3 PM
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| The area depicted in the pink cloud like feature in this map is an area most at risk for flash flooding this afternoon and evening from Isaias. |
We're now just beginning to get into the thick of it in Vermont now with Tropical Storm Isaias.
Heavier rain bands are starting to move northward across the state. Rotating storms are starting to appear in far southern Vermont. As of 2:35 p.m., there was a tornado warning just north of the Massachusetts border for areas around Jacksonville and Wilmington, Vermont. The warning has since expired.
Other potential spin ups are possible in southern Vermont.
I'm starting to think that the track of Isaias will move even slightly further west than we thought this morning. Perhaps up the western shore of Lake Champlain? I'll want to keep watching that.
If this slightly more western track happens, there would still be a real flash flood threat , especially over western Vermont. But it would increase the danger of flash floods in eastern New York. Remember, the heaviest rain usually falls along and west of at tropical storm's track through the Northeast.
NOAA in a flash flood "Mesoscale Precipitation Discussion just issued around 3 p.m. said flash flooding is likely in most of Vermont and eastern New York over the next several hours. Highest risk areas are in mountainous terrain like the Catskills and Adirondacks of New York and the entire Green Mountain chain in Vermont, along with urban areas like Albany, New York. I'd add places like Burlington, Rutland and St. Albans as at risk areas for urban flooding.
Earlier this week, I was looking forward to perhaps a beneficial inch or so of rain in Vermont from Isaias. Instead, we're in for too much too fast. I still don't think this will be as bad as Irene, but I DEFINITELY think we should take the flash flood threat very seriously.
The most torrential rains will ramp up starting in far southern Vermont any moment now and work northward. There area also already some pretty heavy rain bands in central Vermont, too.
Again, the heaviest rain will be in western Vermont, but all of the state is at risk of heavy enough rain rates to create local flash floods, road washouts and culvert collapses. This situation should go on until, I'd say, about midnight.
A slightly more western track could open up a little bigger chunk of eastern and southern Vermont into a tornado threat zone. The threat is low, but by all means NOT zero. It's also going to be hard for any tornado warnings to go out. This type of tropical storm creates situations in which rotation spins up really fast, even before any forecaster can eye trends and see the rotation starting.
By the time the tornado warning goes out, chances are the rotation, or even a tornado, has come and gone.
There is a tornado watch in effect for far southern Vermont. What really blows my mind is that this is the second time in three days parts of Vermont have been under a tornado watch, and it's the third time that's happened this year.
So far, there have been no confirmed tornadoes in Vermont this year. Let's keep that record going!
We're still looking at strong winds in many areas as this develops into the evening. All of Vermont can expect some gusty winds early tonight, and possibly overnight. The strongest winds still look like they will be over eastern Vermont and the western slopes of the Green Mountains.
Be prepared for scattered power failures as winds ramp up to 55 mph gusts in a few spots. The strongest winds will come after the heaviest rain has arrived and the winds will taper off after the heaviest rain ends, as it looks now.
I'd continue my advice to stay home this evening, unless you're in a flood prone area. Keep an ear out for any new warnings that might be issued, be there for strong winds, flash flooding, or even, possibly, a tornado warning or two.
PREVIOUS DISCUSSION
It's time for a deeper dive into this storm, since it's now on its way into the state this afternoon and evening.
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| Heavy rains are coming with Tropical Storm Isaias. Two to five inches of rain could easily cause flash flooding. |
As of 11 a.m., Tropical Storm Iasais was over Maryland, and the forecast calls for it to be about over Albany, New York this evening, then go right up the Champlain Valley to a position near Montreal by early Wednesday morning.
That's an odd track for a tropical storm, but whatever. This year has been supremely weird so nothing surprises me any more.
Isaias was causing all kinds of problems along the East Coast today, as you'd expect. Like most tropical storms that move northward up the coast, the heaviest rain tends to be along and just west of the path. Highest winds are usually along and just east of the path.
Tornadoes are often possible with tropical storms and Isaias seems to be good at producing tornadoes. I think this is mostly because Isaias is an "inland runner," as opposed to most tropical systems that go over or just off the East Coast.
Isaias' path puts heavily populated areas of the Northeast under threat of high winds, severe thunderstorms and tornadoes. As it moves north, the tornado threat will increase over much of New England.
There's only a very low chance that any particular spot would be hit by a twister, but I'm just saying those are a possibility. This includes southeastern Vermont. It actually looks like NOAA's Severe Storms Center will issue a tornado watch any minute for southern and central New England, including far southern Vermont.
Because of mountains and terrain, it's hard to pick out rotation in storms via radar in southeastern Vermont, so a brief spinup could really come as a complete surprise to a handful of people down there.
Already, a rotating storm did produce a brief tornado warning early this morning near Brattleboro
However, the principal threats from Isaias in Vermont is wind and flash flooding. The forward speed of Isaias is a little faster than expected, so it has slightly less time to weaken before reaching Vermont. More importantly, its track further west than we thought at this time yesterday puts most of Vermont at a wind and flash flood risk.
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| Shaded areas on this map, especially zones in pink and red, are at risk for flash flooding from Isaias. |
The rain will be heavier with this path, especially in the western half of Vermont. Yes, it's been dry, so I"m still not expecting another Irene.
However, this is important: Rainfall rates will be intense this evening, notably across the western half of Vermont and eastern New York. The storm isn't even here yet and there have already been bursts of heavy rain
Urban flooding and dangerous flash flooding is likely, especially in hilly terrain. Watch out for road washouts, and be prepared to move to higher ground if floods threaten.
For gawd's sake don't drive through flooded roads. You could easily either stall out, or the road beneath could be washed away.
With Isaias now apparently going to target Vermont directly, expect higher winds, All of Vermont is now under a wind advisory, with gusts in some areas of 55 mph likely. The strongest winds are likely in southeastern Vermont and along the eastern slopes of the Green Mountains.
We sometimes get winds of this strength in the winter, and those tend to only cause minor damage. But here's the difference:
Leaves are on the trees. It's summer, after all. Each leave acts like a little sail in the wind. These thousands of little "sails" on each tree will tug branches and tree trunks much further sideways than if the trees were leafless.
That increases the chance that some branches and trees will break, taking power lines down with them.
Winds could easily gust to 50 mph in eastern Vermont and along the western slopes of the Green Mountains. Scattered power outages are a good bet.
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| Shaded areas are at risk of a few tornadoes from Isaias today. Highest risk in yellow, lower risk in brown, lower yet in green. |
One thing I've noticed with rare Vermont tropical storms is that as the storm passes through and as it begins to depart, strong north winds develop in the Champlain Valley. I noticed that during Tropical Storm Irene in 2011. Most of Vermont had devastating floods but really not that much wind. The Champlain Valley though, experienced strong winds and tree damage.
Forecasters are looking at that possibility later tonight.
So here's what to do:
1. Charge up your devices now, in case the power goes out. It would't hurt to charge up the flashlights and LED candles, too. No real candles, please. It's a fire hazard.
2. If you haven't already done so, get your lawn furniture and other stuff that can blow around inside, RIGHT NOW.
3. Stay home later this afternoon and tonight. We should be used to that, with our self-quarantining we've done for months over the coronavirus.
4. If you must go out, don't drive through flooded areas. Be very careful driving at night. It's really hard to see washouts and flash floods ahead of you until it's too late to stop the car.
5. Listen to trusted sources for the latest updates and warnings. The National Weather Service office in South Burlington is superb. All the local TV stations in Vermont have excellent, talented meteorologists, so we're blessed there. The Eye in the Sky people in St. Johnsbury are top rate also.
Don't bother with a lot of those apps you can get for phones. They're terrible. Also, have more than one way to get weather warnings. For instance, if the power is out, you won't get warnings from the TV. But if you also have a battery operated weather radio, you're still good.
6. I've said this before and I will say it over and over again. Do NOT whine when a weather warning for a town dozens of miles away interrupts your viewing of the season finale of "Real Housewives of Enosburg Falls" or whatever you're watching.
The TV stations don't have the ability to tailor warnings to just the few people that are affected by the warning. Be glad the TV meteorologists are warning people of danger, and know they will do the same for you if you're threatened by a storm.
7. Sit back and enjoy the storm. There's something sublime about listening to a downpour roar on the roof on a humid summer night.
By the way, this storm will be out of our hair quickly on Wednesday morning. From there, we'll have a long period of tranquil weather.
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