This is our final call forecast for Hurricane Henri, which is quickly moving toward the state. We've discussed the overall setup in the past few posts, so this one will focus only on timing and impacts.
Below: Hurricane Henri coming into focus on radar. Note the rain over NYC. That is part of an inverted trough and looks more like a quasi-predecessor rain event (PRE). Interesting meteorology at play this evening. The rain is expected to stay away for the most part.
We expect rain to begin along the coastline between 3-5am. Although it may be raining we do not anticipate tropical storm conditions (winds 39 mph or above) to begin in Connecticut until approximately 8am. This means that travel will be less than ideal, but possible. Conditions will quickly deteriorate however as the rain moves from south to north.
Because this is a tropical system, you should not expect it to rain or rain heavily all the time. Rain will likely come in bands, which will also bring strong wind gusts with them.
These bands will rotate into the state over the course of the morning, and by noon conditions will have deteriorated across the state. Rain will be extremely heavy at times during the day and evening, and winds will pick up as the center of Henri gets closer to your location.
The worst of the wind will be late tomorrow morning through tomorrow evening. The winds will diminish late tomorrow night but the rain will continue in bands into at least Monday morning. Some guidance keeps the rain in our state through the day Monday.
The storm is likely completely gone by Tuesday morning, though this is a less confident part of the forecast due to the wide variations we see in later track guidance. This will likely need to be adjusted as we monitor the progress of the storm.
Landfall Location & Intensity
Last night we narrowed down what we believe to be the landfall zone (where the center crosses), and that zone was between New Haven, CT and Westerly, RI. Since yesterday we have seen some shifts east by the guidance, but this isn't a shift out to sea or toward less impact, as some on our Facebook page have wondered.
Often, landfall locations can shift as the center of a system wobbles close to shore or the steering current is a little stronger or weaker than anticipated. Here, although we've seen some eastward shifts in the guidance, we do not believe it is enough to shift our landfall zone. As a result, we think a landfall will occur between New Haven and Westerly, and for that landfall to be near the RI/CT border.
What does this mean? It reduces the wind threat in western Connecticut a bit, but increases the flooding hazard for both western and central Connecticut. This is because, as you will see below, the guidance is fairly consistent in showing Henri bisecting the state from a southeast to northwest heading.
The GFS run below illustrates this track well enough, though we think the landfall location will likely be a touch further west.
We think it could reasonably be between 65 mph and 80 mph at landfall. At 75 mph, Henri would be the first New England hurricane since 1991 (Bob) and first CT hurricane landfall since Gloria in 1985.
It may be a very close call, but it will have no impact on overall conditions.
We think that the eastward shift in track has reduced the wind potential slightly, but it won't really make much difference in the scheme of things. We expect the following during the worst part of the storm:
- Coastal areas: Sustained winds of 40-55 mph with gusts between 60-70 mph. Some isolated areas in SE CT may see higher gusts. Winds will be stronger the closer you are to the center, meaning the stronger winds will likely be east of New Haven and strongest in New London County.
- Inland areas: Sustained winds of 30-40 mph with gusts between 45-55 mph. Isolated higher gusts are possible near the center of the system.
Unlike other tropical systems in New England, the wind field will not be as large and it will not be as strong as Henri is expected to be weakening on final approach and will not have a robust extratropical transition which usually expands the wind field. The closer you are to the center the more likely you see damaging wind, especially along the shoreline.
Coastal Hazards: High Impact
We expect high impact storm surge and beach erosion. The NHC has upped its surge potential to 3-5 feet of surge, and we agree. The push north by Henri will push water into Long Island Sound, bringing significant flooding in a number of locations. In fact, some evacuations began in anticipation of this. Again, we do not expect the kind of surge we saw in Sandy, as Sandy was a stronger and much larger storm that was able to push incredible amounts of water onshore, but it will be very bad in some locations.
We still expect the combination of wind, rain, waves, and surge to cause major beach erosion. Be aware if you are along the immediate shoreline. Below is the NHC peak surge forecast.
Note that not every inch of coastline will see this kind of water rise, but the surge potential is serious.
As mentioned last night, the eastern side of a tropical system tends to see severe weather in the form of tornadoes. These generally are quick and relatively weak spin ups. This is something we will be watching on the eastern side of the system depending on where it makes landfall. We do not expect severe weather for most of the state. But there is a low tornado threat in eastern CT depending on landfall location.
Rainfall: High to Extreme Impact
Rain is the story of this storm and we have high concern for major flooding in parts of Connecticut.
This will be a slow moving tropical storm or hurricane and the center will cross the state. That means that central and western CT in particular needs to watch out as we see banding set up tomorrow. Flood watches are up for the entire state.
We are editing our rainfall forecast to be a bit more specific. In eastern CT (Windham, New London counties) we expect a general 2-5 inches of rain. In central and western CT, we expect a general 5-10 inches of rain with some isolated higher amounts.
Particularly concerning would be a Euro like track, which brings the storm across CT on Sunday, and then slowly brings it back east just north of CT on Monday dropping additional heavy rain. Places in this 5-10 zone will come in lower depending on the exact track and banding of Henri, but it is important for each community in this zone to be prepared for flooding rains.
Central CT in particular should watch out as we just had a flash flooding event.
Flash flooding on the order of what could happen is a bona fide life threatening event, especially if you are on the roads and driving through flooded roads. we cannot emphasize enough that if you encounter flooded roads do not drive through them. River flooding will need to be watched as well.
A moderate risk for flash flooding remains in place from the WPC.
We expect widespread and long duration power outages. The outages will be more likely in central and eastern CT, but expect outages wherever you are. Even with the reduced wind potential, the combination of wind, significant rain, and the long duration nature of the storm will take down numerous trees and power lines.
Overall Impact: High
We already know that there will be folks that are spared by the storm and will call bust. Congrats in advance to them. But for a substantial part of Connecticut, the combination of wind, rain, coastal impacts, and power outages means that this will be a major weather event. A storm need not be the Great 1938 Hurricane to have a major impact.
Once again, the impacts will vary depending on location and track (wind at the shore, rain in central and western CT) but this looks to be on par with some of the high impact events we've seen in the past.
SCW will be providing constant updates as we receive additional information. As we track this system, please understand that we will be much slower to respond than usual.
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Thank you for reading.
-SCW Team (written by DB)