Elsa And You: Principal Storm Threat Is Flooding

Tropical Storm Elsa over the Carolinas this morning.
The storm is raising flood alerts from North Carolina to
Maine, including parts of Vermont 

Weak Tropical Storm Elsa, over South Carolina as of early this morning, is set to make its soggy trip up the Eastern Seaboard today and tomorrow.

Tropical storm warnings extend all the way up the coast to Massachusetts, which is relatively rare, especially this early in the season. 

Though high winds might be a problem along the coast in some spots, Elsa will mostly be remembered for its heavy rains and flooding.  

Flash flood watches extend from North Carolina to Maine, and those watches include southern and central Vermont. 

Most of the areas under the flash flood watches have been repeatedly raked by torrential thunderstorms over the past week or two, so soil moisture there is higher.  Which means Elsa's downpours would have an easier time producing flash floods. 

The National Hurricane Center has done a fantastic job forecasting the position and strength of Elsa ever since it really cranked up near Barbados last week. So I have no reason to doubt its expected track up along the coastline, crossing southeastern Massachusetts Friday morning or early afternoon.

Here in Vermont, most of the heavy rain will be an indirect result of Elsa, though southeastern Vermont in particular will get an extra dose of rain from the actual storm tomorrow morning. 

The rains today and tonight around here will mostly be brought along by tropical moisture Elsa is helping to bring north, plus a weather pattern that takes full advantage of that moisture. 

Weather radar had lots of scattered showers around early this morning as this tropical moisture began to take hold. The rain will grow steadier and heavier as the day wears on. By late afternoon, overnight and Friday morning, the rain will really come down hard at times.

As I've said before, the heavy rain will do more good than harm, especially in northern Vermont, which has had less beneficial rains than southern Vermont in the past couple of weeks. That previous southern Vermont rain points to some danger from this new, wet episode.

Tropical systems moving north into New England almost always create a flood threat, and Elsa is no exception.

Southern Vermont has been on the edge of all that intense thunderstorm activity I mentioned that's been going on along much of the East Coast.  From Route 2 south, rainfall has been above normal in Vermont over the past week.  So the ground is wetter there. Plus, the heaviest rain from this episode will cross southern and eastern Vermont.  

Which is why that part of the state is under a flash flood watch. The area under this watch is roughly south and east of a Middlebury to St. Johnsbury line. 

Hollyhocks and other flowers brighten things up in my St.
Albans, Vermont gardens on a dark, overcast morning today.
Those clouds will ultimately result in heavy rains by tonight.

Tropical Storm Elsa will certainly NOT be a repeat of Tropical Storm Irene - we're not expecting a full blown flood disaster. But those of us under the flash flood watch really need to take it seriously. 

Torrential periods of rain falling on the steep hills of the Green Mountain State can really send blasts of water roaring down small streams, wrecking culverts and undermining back roads. 

 The bulk of the heavy rain and flash flooding will come after dark, when it's harder to see washouts and high water when you're out there driving. 

If you're vacationing here in Vermont and have set up your camp site or RV right next to a small stream or river, I'd move uphill right now to be on the safe side. 

Because most of Vermont has either been in drought or at least abnormally dry pretty much all of this year so far, the larger rivers likely won't flood. They're running awfully low to start with, so it would take a lot of water to fill them up. 

It's the small streams, creeks, low lying areas and typical flood prone areas we have to watch out for. Even places outside the flash flood watch should pay attention for the risk of some small streams getting  out of hand or some street flooding in more urban areas

As always, don't drive onto a road covered by water. You don't know how deep it is, and you don't know whether the road has been undermined. Will it collapse when you drive your car into it? Trust me, don't take the chance. 

Overall, we'll get anywhere from about 1.25 to three inches of rain by Friday afternoon.  There will be locally heavier amounts in central and southern Vermont, which is another good reason why there's a flash flood watch posted there.

Don't worry at all about high winds from Elsa in Vermont. Ain't going to happen.  

In southeastern New England, though, strong, damaging winds could be a problem Friday morning. I expect plenty of tree and power line damage down that way tomorrow. There might even be a couple brief, isolated tornadoes in that neck of the woods. 

Needless to say, tomorrow is NOT the best day for your Boston, Cape Cod, Nantucket, Martha's Vineyard or Block Island getaway.  

I said there's lots of tropical moisture around that is leading to the heavy rain, and that's true. The air won't exactly feel tropical, though.  Temperatures won't make it to 70 today and will barely crack the low 70s tomorrow. 

Cool high pressure in Quebec is feeding chilly air down toward us. That tropical moisture is being forced to glide up and over the cooler air. The fact that this air has to rise is one reason why it's going to rain so hard.

 The weekend looks nice, with temperatures just a tad cooler than normal (mid to upper 70s). Seems like we always have gorgeous weather right after a tropical system passes nearby.

When we get into next week, we'll  muddle into some typical summer weather, with near normal highs around 80, with the air having a vaguely humid feel to it.  There will be a risk of showers and storms each day, but most of the time will be dry.