Good morning from Southern Connecticut Weather!
For most of the last week, we've been watching the potential for a subtropical or non-tropical coastal storm to develop. The trend has been toward a more impactful system, and with increased confidence that we are affected it is time to take a closer look. Let's dive in.
For most of the last week, we've been watching the potential for a subtropical or non-tropical coastal storm to develop. The trend has been toward a more impactful system, and with increased confidence that we are affected it is time to take a closer look. Let's dive in.
Above: 00z GFS 500mb depiction of the coming storm. Two distinct elements will combine or "phase" to bring us our storm. There is still significant uncertainty over exact track and intensity.
The Setup
This time of year, it is exceptionally rare to get purely tropical systems up this way. However, October has produced subtropical or non-tropical "hybrid" systems that have been impactful for the region. This time we have a mostly non-tropical low that will develop off the southeast coast. It will have some tropical moisture/influence that may allow it briefly to be a subtropical storm, but whether or not it gets designated is irrelevant.
The Setup
This time of year, it is exceptionally rare to get purely tropical systems up this way. However, October has produced subtropical or non-tropical "hybrid" systems that have been impactful for the region. This time we have a mostly non-tropical low that will develop off the southeast coast. It will have some tropical moisture/influence that may allow it briefly to be a subtropical storm, but whether or not it gets designated is irrelevant.
Using the phase change chart above from the 00z European model, we can see how it starts out as a cold-core (non-tropical) system, but then perhaps tries to acquire some tropical characteristics as a warm core system before the storm matures into a warm seclusion cyclone.
Because it may be some sort of hybrid, we expect a large, sprawling, area of low pressure, one which will deliver rain and wind far from its center.
Because it may be some sort of hybrid, we expect a large, sprawling, area of low pressure, one which will deliver rain and wind far from its center.
Above: the 06z GFS depiction of the storm's evolution. Note how it develops off the SE coast, and then as it phases with the energy from the Lakes region it intensifies and brings a band of rain into New England. This is only part of the story.
Potential Impacts
There is still significant uncertainty over track and intensity. The models have been waffling on intensity, while the track has become a little more stable. With such a large storm we see a few hazards.
Rainfall
Because it has been so dry, I am doubtful that we have a significant risk for flooding. That may be confined to heavier rain zones in the Mid-Atlantic. The duration of rainfall if the track is further north however bears some watching.
Coastal Flooding
I do have some concern about coastal flooding. While we may dodge a bit of a bullet with the storm coming Sunday and after one of our higher tide cycles for the year, the track of the system may bring persistent flow into Long Island Sound, which could cause some coastal flooding issues, especially in SW CT. This is something to closely monitor, as the exact track and wind direction will impact what happens. Folks along the coast should pay close attention as we could see minor to moderate flooding as of this post.
Potential Impacts
There is still significant uncertainty over track and intensity. The models have been waffling on intensity, while the track has become a little more stable. With such a large storm we see a few hazards.
Rainfall
Because it has been so dry, I am doubtful that we have a significant risk for flooding. That may be confined to heavier rain zones in the Mid-Atlantic. The duration of rainfall if the track is further north however bears some watching.
Coastal Flooding
I do have some concern about coastal flooding. While we may dodge a bit of a bullet with the storm coming Sunday and after one of our higher tide cycles for the year, the track of the system may bring persistent flow into Long Island Sound, which could cause some coastal flooding issues, especially in SW CT. This is something to closely monitor, as the exact track and wind direction will impact what happens. Folks along the coast should pay close attention as we could see minor to moderate flooding as of this post.
Above: the GFS showing the potential surface winds of the storm. I am posting this to illustrate the flow that could cause coastal flooding, Strong winds into the Sound could cause problems.
Wind
Finally, as you can see above from the GFS, this could be a windy storm, especially at the coast. This is also dependent a bit on track, though between a strong low and high pressure to the north, Sunday and Monday look breezy to windy with a pressure gradient on its own.
The coast is most likely as usual to see the strongest winds, and the heightened concern comes because there are still leaves on the trees. This won't be the windiest storm ever, but power outages will be possible.
Wind
Finally, as you can see above from the GFS, this could be a windy storm, especially at the coast. This is also dependent a bit on track, though between a strong low and high pressure to the north, Sunday and Monday look breezy to windy with a pressure gradient on its own.
The coast is most likely as usual to see the strongest winds, and the heightened concern comes because there are still leaves on the trees. This won't be the windiest storm ever, but power outages will be possible.
Above: 925mb wind speeds from the GFS.
Below: 925mb wind speeds from the Euro. These are winds just above the surface and will not fully translate to ground level.
Below: 925mb wind speeds from the Euro. These are winds just above the surface and will not fully translate to ground level.
The 925mb winds above are a little impressive, showing 50kt+ winds well into CT Monday morning. Not all of this will translate to the surface, but as we get closer we need to watch to see if this signal increases some. As it stands, peak winds inland may be 30-40mph, while at the coast it could be 40-50mph. Again, not the worst, but enough for possible scattered tree damage and power outages.
Overall, this is a system to pay attention to. The timeframe for impacts would be as early as Sunday morning through early Tuesday, with specific timing to be determined. Now would be a good time to check your storm supplies--just in case we do see those power outages.
Stay tuned.
As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.
Thank you for reading SCW.
-DB
Overall, this is a system to pay attention to. The timeframe for impacts would be as early as Sunday morning through early Tuesday, with specific timing to be determined. Now would be a good time to check your storm supplies--just in case we do see those power outages.
Stay tuned.
As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.
Thank you for reading SCW.
-DB
