As Tom Brady prepares for his 10th Superbowl a round of snow will likely impact southern New England. A very active weather has established itself across the North American continent and the next disturbance in the pattern passes by the region Sunday.
For the last two days or so the forecast for Sunday has been steadily trending towards a snowier solution. What was once expected to pass harmlessly out to sea has trended significantly northwest. Shown in the image below is total precipitation through 1am Monday for the last 8 (2 days) model runs for the GFS model. Note how the precipitation has steadily shifted northwest.
For reference, any blue shading is >0.5″ of liquid precipitation which roughly correlates to 5″ of snow. So what could lead to such a trend? DATA! Any forecast system is only as good as the initial data put into the system. At the start of the above trend loop, the storm system is located approximately here south of Alaska:
Now when this mornings computer model runs come in, the storm system is located approximately here over Washington state:
The key obvious difference being that the storm system is no located over land and not the open ocean. Satellites and aircraft do a decent job of sampling the atmosphere is remote locations, but there is no substitute for sampling the atmosphere over land. Over land is where meteorologists routinely launch balloons that sample the atmospheric conditions as they ascend to the heavens.
Now that the storm system is located over land, the data input into the model is much better, giving confidence to forecasters that Sunday afternoon will be a snowy one.
One thing is for certain with this system…it is trucking northeast. The loop above is only 13 hours long and snow in most locations only lasts for 6-8 hours. So while this system has lots of moisture associated with it and snow will fall at a decent rate, accumulations are limited by duration.
Right now, here are my current thoughts in terms of snowfall:
-Chris
Chris Hampton Weather 