What I am watching now is the circulation of Arthur and the cold front hitting over the south coast of Massachusetts. You can see on the radar loop an area of red pop-up where this is taking place. The concern I have is for some localized serious fresh water flooding as we see areas have up to and maybe exceed 8 inches of rain. This amount of water will put some serious strain on some roads and basements and if there is any wind could push trees over if the ground becomes too saturated.
The most intense rain will last another 3 to 4 hours and that is why the rainfall amounts are growing so much.
The heaviest rain continues south of Boston as Arthur, now weakening moves northeast off the coastline.
The strongest winds and highest seas will remain offshore and this is just going to be an unusually wet July 4th.
The radar loop below is from 6:30 this evening. You can, if you look closely, see the circulation of Arthur is still not really part of the rain over metro-west, the north shore or even Boston. As the evening progresses, the Cape and Islands will see the most wind, but it won't be memorable.
Most of the region east of Route 495 will see 2-4 inches of rain will much less west.
Some areas will close in on exceeding 6 inches of rain. This map shows an estimate of rainfall so far. The heaviest is centered where you see the red. The green boxes are flood warnings for the same area.
Winds will gust to tropical storm force over parts of Cape Cod and Nantucket and get close over the Vineyard. As I mentioned earlier today, there will be some power issues, but this isn't a storm which will shut off the lights for all of Cape Cod.
The heaviest rain is over by midnight, but I expect lighter rain to continue for several more hours after that. Skies will clear in the morning and the bulk of tomorrow is going to be nice. If you live along the north shore the first few hours after sunrise might be cloudy, but it will turn out to be a nice day, I promise.
Winds will be a bit gusty tomorrow as the storm moves into Canada. Warmer and dry weather continues Sunday with even warmer and more humid weather for Monday.