A quick update with a snow map for you this evening. I will tweak this further after dinner, but wanted to give you something early. Notice the 2 to 5 inch amounts cover much of the area, with less along the coastline, especially south of Boston and well west. Within that range the 5 inch numbers will likely occur closest to the bulls-eye I drew in Worcester County. Boston will likely receive about 2 inches. If the rain holds longer at the beginning of the storm, it could be an inch of slush.
The precipitation starts in the morning as snow inland, but rain or mixed rain and snow along the coast. It will slowly change to snow from west to east later in the afternoon and then end in the evening well before midnight. This still will become a big storm in the ocean, but just graze the area. There is a winter storm watch for areas in blue. This corresponds with those areas most likely to reach 4 to 6 inches of snow or perhaps a bit more in the higher elevations.
Morning Entry Below
Yesterday I was writing about the discrepancy between the two primary models forecasters use when predicting the weather. This morning, the models have come into closer agreement. The American model is moving closer to the European model’s idea for the upcoming storm.
The storm isn’t going to have a blockbuster impact on the region in spite of the fact that it will likely become an enormously intense storm in the ocean. The highest snowfall will be along the coastal plain, but because of a mix or complete change to rain for a few hours Saturday, amounts will be lower over Cape Cod and the South Shore. There is even a chance the rain-snow line moves further inland.
We don’t have a lot of cold air to start with, so the rain-snow line is an issue at least in the beginning. You can expect the precipitation to begin late in the morning Saturday, and roadways will be wet for a few hours before becoming snow-covered later in the day.
The snow will continue the first half of the overnight Saturday evening, and if it’s raining early where you are, it will eventually change to snow before it ends. Areas west of Route 128 will likely not see much, if any, rain, while Boston will see a few hours of mixed precipitation and Cape Cod will see more rain than snow.
I want to see the afternoon model run before putting together a snowfall map, which I will do later today. Right now I’d say we are looking at something like 4, 5, or 6 inches for the areas that stay all snow, but much less of course where it rains longest before the changeover. Please read that line again. I’m not forecasting 6 inches of snow, just giving an idea of how things look right now. This isn’t a big impact storm, but in a winter with so little snow it’s a snow event for many.
This afternoon, there are going to be new versions of all the models, and this new information will likely alter my forecast. If the storm track is significantly different, then more of what I wrote will need to be revised. I’ll update on Twitter as well @growingwisdom as I see new data coming in, with a full update here before the evening commute.