Saturday and Saturday evening are all that left to get everybody to a safe place before dangerous weather from Henri arrives on Long Island and across southern New England overnight.
The computer forecast models have focused in on the eastern end of Long Island, New York as the initial landfall point for the center of the storm, however the trend in a number of the models has been farther west. The center location at landfall is critical, because it drastically affects where the water gets pushed over the coastline, and who gets the strongest winds.
If Henri approaches the coast near Montauk at the eastern tip of Long Island, there will be time for the rotating winds to push water east to west through Long Island Sound, for example. That would push the ocean water as far west as LaGuardia Airport in New York City. The forecast is for it to surge three to five feet above normal high tide along the entire Sound in that scenario. As just one example. The coastline of Connecticut, Rhode Island, and Long Island, New York is full of harbors and inlets that would be affected by the surge.
If Henri slides farther west and comes ashore closer to the center of Long Island, however. Water will surge into the inlets, bays, and rivers and over the south-facing beaches. Again the forecast is three to five feet above normal high tide in those areas and the effects on the northern side of Long Island would be different.
Every part of Long Island and southern New England is going to feel the storm and the ocean water will rise and be filled with chaotic, powerful waves. The unknown is, exactly how high and violent the water will be. The point is, a slight, unforecastable difference in the landfall point makes a big difference in exactly who get the worst effects, and where the ocean water is pushed the highest.
The most widespread effect of Henri might end up being the extensive power outages that are expected. Trees are in full leaf, and the ground is saturated from a very wet summer. In New England, the remnants of Fred just brought another round of soaking rain. Even a tropical storm can cause long-lasting outages over a large area in this scenario.
Henri will be much smaller in diameter, but probably have winds of about the same strength as Superstorm Sandy when it comes ashore. Sandy barely produced hurricane-force winds over land, yet the electrical lines gave way to falling trees across the region. Prepare today for an extensive period without power.
Think of Sandy. Gas up your car. Get cash from the ATM. Fill any containers you have with water in case a tree falls and its roots break a water line near your home. Put a plastic sheet in your bathtub and fill it up ¾ with water so you can flush the toilet in case you lose water pressure.
Many people are going to prepare and it’s not going to be so bad, but there is no way to know exactly who is going to get the worst, so the entire region has to be ready.
Henri is in the process of strengthening, which is expected to continue through the day while it is over the warm water of the Gulf Stream. As it approaches the Northeast, water will already start to rise along the coastline.
This evening the center of the circulation center will cross the northern edge of the Gulf Stream and the ocean will get progressively cooler. Because Henri is moving relatively slowly – much slower that past hurricanes to hit the Northeast – it will have more time than usual over the cooler water. So it should lose some strength overnight before impacts begin Sunday morning. But it will still have a well-developed circulation that will move a lot of water.
A wild card is a significant amount of dry air near the circulation. If that can wrap into the storm, it will weaken the system to some degree as well. But the degree to which that effect will come into play is not clear.
Once the center crosses into New England tomorrow afternoon, it will lose strength quickly, but will still have strong enough winds to knock down trees and take out power. And the system will be crawling. It will be late Monday or perhaps on Tuesday before the remnants of Henri eject to the northeast.
Due to the slow forward speed of the storm and the saturated ground across the region, there is a significant risk of flooding. A corridor of heavy rain is forecast to accompany Henri into southern New England. Stay alert! Don’t challenge flooded creeks, even if they are normally benign.
It’s a beautiful day across the Northeast and New England today – perfect weather to prepare and get to safety.
In the Caribbean, Hurricane Grace made landfall overnight near Tecolutia, Mexico well north of Veracruz with 125 mph winds – a strong Category 3. It is now dying out over the tall mountains in the center of the country, but there continues to be a significant threat from the winds and torrential rain associated with the strong circulation.
Out in the Atlantic, a tropical disturbance is heading north. It might eventually develop, but it would be in the middle of the ocean.
Nothing else is in the offing through the middle of next week, at least.