Once again Wednesday we have a lot of meteorology to get to as the atmosphere continues to provide us with plenty to forecast. Let’s start with the inevitable showers and heavy downpours that are on the way.
Most of these showers occur Wednesday afternoon. A slow-moving cold front is pushing east today and will pass offshore Thursday morning. Behind it, drier air will finally put an end to one of the most humid September stretches on record. Dew points will fall from the 60s down into the 50s, and the air will feel refreshing.
Wednesday afternoon and evening, some of the showers could contain heavy downpours as well as thunder. Street flooding is possible and of course, in areas that have seen so much heavy rain, this will only exacerbate an existing issue.
The bulk of the showers will end by the middle of the evening and clearing will take place for Thursday. You’ll notice the air drying out and temperatures will be in the 70s. It will also be very comfortable for sleeping on Thursday night. Friday looks sunny and seasonably cool.
Things go downhill once again Friday night into Saturday as Hurricane Lee approaches. Although the storm will not make landfall here in Southern New England, it will eventually come onshore along the Maine or Eastern Canadian coast. As the storm moves northward into colder waters, it will be undergoing a conversion from a tropical system, one with a warm core, to an extra-tropical one with a cold core.
When these transitions take place, the wind field expands well beyond the center of the storm. This is why even though the core of Lee will remain out over the ocean, as the wind field expands it will impact New England. The exact track within 25 to 50 miles is going to determine how much of the stronger winds on the left side of the storm end up coming on shore.
I would say there’s a high likelihood of tropical-storm-force winds — which are 39 mph or higher — pushing west even to Route 495. If the track were a little further east then those heavier winds will follow and perhaps only hug the coastline.
Either way, the strongest winds are going to be over Cape Cod, where gusts could reach over hurricane force. This will likely create some power outages.
There will also be a heavy swath of rain on the left side of the storm. Here again, how close to the coastline the storm is will determine how much of the heavy rain we see and how far west that pushes. It’s likely that this heavy axis of rain will produce anywhere from 1 to 4 inches of rainfall in a relatively short amount of time leading to the potential for flooding.
Because the storm is going to stay offshore, the winds will be north or northeast and then meander to a more northwesterly flow as the storm heads into the Gulf of Maine. Areas that face that direction will see the most beach erosion and potential for a higher storm surge. Wave action will be large and contribute to the coastal issues. Tides are not astronomically high this weekend, that will help to avoid major coastal flooding.
I would say the most likely scenario is that this feels like a rainy, strong nor’easter. If the models and the guidance we use push the track farther out in the ocean, then it would be more like a light to moderate nor’easter, and some inland areas may experience nothing more than breezy conditions and clouds while the immediate coastline has stronger weather.
Stay informed with the latest forecast, as the intensity of the rain and wind and coastal flooding will need to be clarified in the coming days. For those of you who live along the immediate coastline within, say, 10 miles, especially Cape Ann and Cape Cod, I would say think about how you would handle a strong tropical storm and prepare for power outages. Boats could come out on Thursday or Friday if needed.
If there are going to be watches and warnings issued, that will start happening either Wednesday evening or more likely Thursday. There’s still uncertainty with this so keep up with the latest information as it can and will change.