This evening confidence is growing that Coastal Maine will see some accumulating snow Saturday afternoon and at least the first part of the overnight. I have put together a first look at accumulations, but this will likely be refined tomorrow as I get new information. A track further west, closer to the coast, would mean higher snow amounts while a shift east would lower these numbers. More on Friday.

Morning Blog
It seems like every storm has some discrepancy between the two primary models forecasters use when predicting the weather. For this weekend’s upcoming storm, the American and European models come closer than usual to agreement.

Before we get to any storminess we can enjoy another pleasant day tomorrow. Highs will be in the lower to middle 30s along the coast and colder inland.

On Saturday a low pressure system will move northward from the Gulf Coast and then pass out to sea south of New England. The storm isn’t going to have a blockbuster impact on the region in spite of the fact it will likely become an enormously intense storm in the ocean. The pressure of the storm will deepen very quickly. Meteorologists call this type of rapid intensification “bombogenesis.” I love getting to use that word. The highest snowfall totals will be along the coastal plain, but even so, there is a chance we won’t see much if any snow. The best chance of accumulating snow will be east of the Maine Turnpike and south of Portland.

Saturday Storm
We don’t have a lot of cold air to start so the rain-snow line is a potential issue at least to start. 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 continues for the first half of the overnight Saturday and if it’s a mix of snow and rain where you are at first it will definitely be snowing during the evening. The storm is moving very fast and we are only looking at about 6 to 8 hours of accumulating snow. This is enough time to get a few inches if we can see the snowfall be heavy enough. There is going to be a very tight gradient with the snow to no snow area. Check out the map from the GFS below. Don’t focus on the snowfall numbers, but notice how compact the area of snow is, which is the forecasting challenge.

I want to see the full afternoon model run before putting together a snowfall map, which I will do this evening. Right now I’d say we are looking at something like a coating to a few inches right along the coastline. This isn’t a bit impact storm, but with so little snow recently, it’s a snow event for many.

Changing Forecast
This afternoon there are going to be new versions of all the models and this could change my thinking. If the storm track is significantly different, then much of the forecast 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 after the evening commute.