An intense storm is going to affect Southern New England beginning overnight and continuing through Tuesday night. This storm will bring strong coastal wind, which will penetrate to a lesser extent inland, and heavy torrential rain with an eventual change to heavy snow. The timing of that change from rain to snow will drastically affect how much snow accumulates.
The winds will arrive Monday evening and strengthen overnight. By Tuesday morning, the wind will be gusting along the coastline. At times during Tuesday, it could be as high as 50 to 60 miles an hour right along the water's edge. These strong winds may produce some power outages. Those winds will subside toward Wednesday morning has that part of the storm dissipates.
Precipitation will come down very hard Tuesday morning and afternoon. For most of us it'll be in the form of rain to start, but changing over to snow from Northern Worcester County and then headed toward Boston for the early afternoon.
The exact time of the changeover from rain to snow will be critical to how much snow you receive. There will be bands of heavy rain and snow rotating around the system during the afternoon. If the changeover occurs as these bands come through, you could expect one to two inches of snow in an hour. However if the change is delayed in your area, that precipitation will simply fall as heavy rain.
This is why the gradient between a little snow and a lot of snow is so tight. This is the most difficult part of the storm: A difference in one or two degrees can mean a couple of inches of snow or over half a foot. The computer guidance we all use to help us forecast is good, but it has a hard time with such volatile and marginal situations.
I think the heaviest bands of snow will be over between 6 and 8 p.m., but there can be lingering snow showers, some of which could be briefly heavy right through the early morning hours. Travel is not recommended Tuesday afternoon once the change occurs. You will not want to be caught on the roads as conditions will rapidly change, and visibility in some areas could be near zero for a while. It wouldn't surprise me if we even heard the rumble of thunder.
Tides are astronomically low right now, so I'm not terribly concerned about coastal flooding. The wind and wave action could produce some beach erosion but other than the strong winds at the coast, we're not going to see flooding like we can in some of these nor'easters.
Heavy, wet snow alone can create power outages, as can strong wind. Some areas will see both of these combined. This means there will be power outages in increasing frequency during Tuesday and lasting into early Wednesday before the numbers start coming down.
Clearing and mild air conditions will take place for Thursday with melting snow and a return to normal conditions.
