Sunday Evening Vermont Storm Update: Rainfall Totals Tick Up A Bit, Wind Threat (Maybe) Down A Little

Late afternoon Sunday updates from the National Weather
Service office in South Burlington, Vermont has slightly'
increased rain totals from tonight and Monday's storm.
A large portion of the state can expect at least two
inches of rain. Click on the map to make it 
bigger and easier to see.

 As I start to write this at 5:15 p.m. Sunday, the rain from the long awaited storm is just moving into Vermont in earnest. 

It will be a very wet night. That will continue on Monday. The flood watch for the entire state is very much still in effect. 

As of this evening, the track of the storm has ticked a little bit east. Sound familiar? That's what last Monday's storm ended up doing. 

In that case last week, the little bit of an eastward shift allowed more cold air to infiltrate the storm, which resulted in more snow and less rain.

That definitely won't happen this time. 

There is really no cold air for this storm to work with. And the dynamic system is bringing a big surge of wet, warm air northward from the subtropics. So, we definitely have no snow-friendly air to work with. 

That means a LOT of rain. The only snow will be at the very back end of the storm, and that snow won't amount to much. 

Very much like last week's storm, a lot of thunderstorms south and east of the storm center this afternoon is affecting its track. Those storms tend to push the track of the storm a little more eastward than if those storms didn't really exist. 

FLOOD THEAT ASSESSMENT

This evening, the storm was over eastern South Carolina. It's forecast to move due north, which would take it right up the Champlain Valley around late morning or early afternoon Monday. 

On that path, the heaviest rain would come closer to Vermont, hence the higher rainfall expectations; Most of us in Vermont under this scenario would get 1.5 to 3 inches of rain, with the highest amounts along the eastern slopes of the Green Mountains and in far southeastern Vermont around Brattleboro.

For the third time this month, this amounts to a storm that's extremely wet by December standards. Winter rain and melted snowfall tends to be lighter in the winter than in the summer. That's because colder air can hold less moisture than warmer air. 

But since so much warm air has been entrained into this storm, and the two previous ones, these systems have been very wet. 

As mentioned this morning, very warm temperatures and high humidity would melt the snow rapidly in higher elevations, adding to the runoff. 

The expected flood crest along the Winooski River at Essex Junction has been increased to a crest of 15.8 feet, solidly in the moderate flood range. At those levels, North Williston Road goes way under water. Also, at that level, expect the water to close Route 2 in Jonesville, Bridge Street in Richmond, Poor Farm Road in South Burlington, and a good chunk of the Intervale in Burlington. 

The good news is at this time of year, unlike in July, there's no crops to destroy. And moderate flood stage won't flood houses along the Winooski River Valley. 

Elsewhere in Vermont, the Hoosick River will come close to moderate flood stage. Most other rivers will either go into minor flood or come close to it. That means field flooding, some low-lying roads closed, ponding of water on other roads, and a hydroplaning on wet highways if you're out there driving tonight and Monday. 

The bottom line, as I said this morning, I still believe downtown Montpelier, Barre, Johnson, Ludlow and other towns smashed by July flooding should fare much better this time. Though I'd still remove items from basements to be on the safe side. 

HIGH WINDS

The threat from damage due to high winds in Vermont have gone down somewhat in Vermont. The western slopes of the Green Mountains are under a wind advisory for gusts to 55 mph. That could  cause a smattering of power outages. 

In general, the highest winds from a storm like this hit east of the storm's path. That puts the eastern half of Vermont in the zone for stronger winds, sort of. The National Weather Service is forecasting highest gusts in the 45 to 50 mph range east of the Green Mountains.

This won't be like the powerhouse wind storm that caused so much damage in Vermont last December. 

CAVEATS

As always, we already know the storm won't play out exactly as we outlined above. There will always be surprises. Probably minor surprises, but there's a slight chance of big surprises, too.

If the storm veers well to the west of the forecast track, say over central New York and the middle or western Adirondacks, the wind threat would be much worse. If it goes a little further east than what I've outlined, rainfall will be slightly lighter, but still substantial, and the flood threat would remain. 

Some late breaking new data from around 5 or 6 p.m. this evening doesn't show much shift in the storm's forecast track compared to forecasts earlier this afternoon.

The new data shows heavy rain in Vermont, with that flood threat. But also similar to forecasts earlier today, the heaviest downpours look like they will go through western Massachusetts and Connecticut, western and central New Hampshire and far southeastern Vermont, and western Maine.

I expect to hear news of fairly substantial flooding in New Hampshire and Maine, probably worse than what Vermont sees. 

I don't think this will be a historic storm, at least around here, but will have quite a few impacts. We should take it seriously.