Good evening from Southern Connecticut Weather.
We continue to track the progress of Invest 98L, which now has 80% odds of development into a tropical or subtropical system in the next two days according to the National Hurricane Center.
What we do know at this point is that a broad and weak area of low pressure is currently forming off the North Carolina coast, and is expected to track northward over the next three days while gradually organizing and intensifying.
We continue to track the progress of Invest 98L, which now has 80% odds of development into a tropical or subtropical system in the next two days according to the National Hurricane Center.
What we do know at this point is that a broad and weak area of low pressure is currently forming off the North Carolina coast, and is expected to track northward over the next three days while gradually organizing and intensifying.
Above: the latest NHC tropical outlook, which shows the possible zone of development for Invest 98L.
Forecast Track
There is still uncertainty over the eventual track of the center, but the overall evolution looks to be of higher confidence. 98L will move east-northeastward this evening and overnight. However, the steering pattern between a strong ridge in the Atlantic and a trough in the Midwest will force 98L (or Fay by that time) to the north.
The trick is how sensitive the center will be to these steering influences. Some guidance has the low tracking more north-northwestward, into the Delmarva or NJ coast, while other guidance pushes the low more eastward, either directly over the state or to our east. Although these track differences are slight, they will have a big impact on what impacts we face here.
Forecast Track
There is still uncertainty over the eventual track of the center, but the overall evolution looks to be of higher confidence. 98L will move east-northeastward this evening and overnight. However, the steering pattern between a strong ridge in the Atlantic and a trough in the Midwest will force 98L (or Fay by that time) to the north.
The trick is how sensitive the center will be to these steering influences. Some guidance has the low tracking more north-northwestward, into the Delmarva or NJ coast, while other guidance pushes the low more eastward, either directly over the state or to our east. Although these track differences are slight, they will have a big impact on what impacts we face here.
Above: the 12z European Ensembles showing the potential tracks of 98L. The European Ensembles are in the eastward camp. A lot of the other guidance, including the GFS (below), bring 98L much further close to the coast, if not inland.
Right now, I lean toward a middle ground between the GFS and European Ensembles. That would place the low near the coast, but just offshore, with a path that may take the center closest to CT. Unlike most tropical systems, because this is a weak low, we're not going to need to worry about stronger winds or anything like that with a close center pass.
Possible Impacts
Heavy rain is by far the biggest potential impact. As you can see above, the axis of heaviest rain however will depend on the eventual track. If this low draws further west, it likely means that we will receive less rain, but increased chances of strong to severe thunderstorms in whatever banding remains with the low.
If the low passes directly over or just to the east of the state, it would maximize the rainfall potential. With the low will come a strong fetch of moisture. Flash flooding is possible. As the track forecast is refined, the rainfall forecast will be refined as well.
Wind does not look to be a major player, as this is likely to remain a relatively weak low. Coastal flooding does not look to be a major threat as well.
Timing
There is also a fair amount of uncertainty over timing. What we do know is that rainfall or scattered thunderstorms are likely both late Friday and early Saturday, but it is unclear if the heaviest rain will fall Friday night or during the day Saturday. The Euro is slower, and brings the bulk of rain on Saturday.
Overall
We will be here with updates each day, as we track the progress of 98L.
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.
-DB
Possible Impacts
Heavy rain is by far the biggest potential impact. As you can see above, the axis of heaviest rain however will depend on the eventual track. If this low draws further west, it likely means that we will receive less rain, but increased chances of strong to severe thunderstorms in whatever banding remains with the low.
If the low passes directly over or just to the east of the state, it would maximize the rainfall potential. With the low will come a strong fetch of moisture. Flash flooding is possible. As the track forecast is refined, the rainfall forecast will be refined as well.
Wind does not look to be a major player, as this is likely to remain a relatively weak low. Coastal flooding does not look to be a major threat as well.
Timing
There is also a fair amount of uncertainty over timing. What we do know is that rainfall or scattered thunderstorms are likely both late Friday and early Saturday, but it is unclear if the heaviest rain will fall Friday night or during the day Saturday. The Euro is slower, and brings the bulk of rain on Saturday.
Overall
- A subtropical or tropical system is expected to develop and bring direct impacts to Connecticut on Friday/Saturday.
- Heavy rain and flash flooding look to be the highest threats, but this potential is highly uncertain due to track sensitivity.
- Wind and coastal flooding do not look to be major impacts from this low, which is expected to remain relatively weak.
- The degree of impact is highly dependent on track, and more time is needed to refine this critical part of the forecast.
We will be here with updates each day, as we track the progress of 98L.
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.
-DB
