Weather

Here’s David Epstein’s latest Henri forecast

Currently the storm is weakening and it’s likely to continue to weaken as it approaches landfall somewhere around Block Island early this afternoon.

By Dave Epstein, The Boston Globe

August 20, 2021

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Sunday morning brought a closer look at Tropical Storm Henri, which continues to spin off the Rhode Island coastline moving north-northwest.

Currently, the storm is slowly weakening and it’s likely to continue to weaken as it approaches landfall somewhere around Block Island early this afternoon.

This track means the highest storm surge is going to be over Rhode Island and the area around Buzzards and Narragansett bays.

I don’t expect to see significant flooding over Cape Cod or along the Massachusetts east coast.

Although storm surges of 1 to 3 feet are predicted, this level is not enough to cause major flooding.

The map below shows in blue the areas expected to have 1 foot of water and shows in yellow the areas expected to have up to 3 feet of water.

It’s important to note that most of the areas are around marshes and beaches and not into our towns.

In areas closest to the storm surge, roads and beaches are likely to experience flooding, and there’s likely also to be some closures, but it’s not going to be a widespread major flooding event.

As the storm gets closer to land, winds will be strong enough that there will be power outages. The number of outages is likely to be highest along the coastline and then slowly fewer moving north.

But even areas around MetroWest and the southwestern suburbs of Boston are going to be susceptible to losing power this afternoon. With the leaves on the trees acting as little sails, they can capture the wind, and the on-and-off nature of the gusts will make it a bit more likely that outages will happen.

The strongest winds should arrive between noon and 4 p.m., and then we will start to see them diminish later on this evening. If the storm weakens a little faster, then the threat of wind damage and power outages will decrease significantly as well.

Rainfall will not be excessive in eastern Massachusetts, but will rapidly increase in central and western parts of the state.

The map below shows a wide possibility of rain totals in the east — none of which will be excessive, but can certainly cause some temporary street flooding.

The reason for the wide range is because these tropical downpours are unpredictable, with some areas receiving an inch of rain in 15 minutes and other areas remaining dry.

The sun may come out between showers, and there is even the possibility of it remaining rain-free on much of Cape Cod most of the day.

The steadier and heavier rain will definitely be to the left of the track of Tropical Storm Henri, and this is where major and perhaps even catastrophic flooding can occur, depending on how high rainfall totals are.

This is probably the most impactful part of this storm and the one that can create the most damage. As we have seen with other tropical systems like the remnants of Fred last week, the intensity of a storm does not necessarily reflect the amount of rainfall that will occur.

There can also be some severe weather in pockets as the storm makes landfall, even with little tornadoes, but these are usually quite weak in this situation.

The risk of showers and thunderstorms will continue overnight and into Monday as the storm moves very slowly in a much-weakened state across northern New England and then eventually into eastern Canada.

Behind the system, it will not turn cool and dry. As a matter of fact, it’s going to turn hot and humid. It looks to me like we have the potential for a heat wave Tuesday through Thursday and even if all three of those days aren’t at 90 degrees, they will be close, and with the humidity, it’s going to be quite uncomfortable.

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It does turn somewhat more comfortable and dryer heading toward next the weekend — something I am certainly looking forward to.