Here is today's videos. I am optimistic you will find it to be useful.
There is uncertainty about how far north a storm from the Gulf states will come on Friday. This morning's NAM is rather bullish on the system. However, it suggests milder weather for the Northeast for a while this weekend before the next cold front arrives.
March is national optimism month. A sense of optimism may help us remain healthy and certainly helps us make others feel better than they would around someone who is always pessimistic. In the weather forecasting business, we may sound optimistic or pessimistic on any given day, but we shouldn't let either emotion dictate the forecast. We might be optimistic about taking the brighter side of things, but I pessimistically add that when we are overly optimistic, things often go wrong. On the other hand, there are many times when one computer model or other atmospheric signal will suggest nasty weather is coming, but that model or signal may be an exception; the other models suggest the nasty weather will not happen and there won't be storm. If we go with that idea, are we being realistic or optimistic? The answer is simple. If we are correct, as we expect to be, then we were realistic with our optimism. If on the other hand, the pessimistic view turned out right, it is clear we were too optimistic to discard the pessimistic possibilities and thus missed the need to be realistically pessimistic. Today's computer models for late this week are a case in point. The latest trend shows a storm affecting the Carolina coast and into Virginia on Friday. Little or nothing is shown farther north, although the Canadian model has shown something on some previous runs. However, which is the correct trend? If we take the optimistic approach, we simply predict no big problem, but is that realistic? Is it optimistic? Is it pessimistic? It could be.
Looking at next week, the GFS ensemble spaghetti plot of upper air winds shows how much agreement there is among members of the ensemble (same model running multiple times using slightly different starting assumptions). The maps are from next Tuesday, Nov. 25, and Thanksgiving Day, Nov. 27. There is good agreement on the first map, but a lot of spread two days later.
The location of lake-effect snow bands is tightly controlled by geography, topography and wind. From this pressure analysis, we see why the wind favored heavy snow staying south of the hardest hit Buffalo snow belts earlier today.
If this timing works out, there would be good travel weather for the Northeast Corridor on Wednesday while snow showers cross the Great Lakes and reach the northern and central Appalachians.
This map from one of my tweets yesterday (accuElliot) showed the wind direction most favorable for heavy lake-effect snow in and near Buffalo. Just a minute change in direction greatly affects the location of the heaviest snow, almost as if you were operating a fire hose. The snow is so deep (more than 4 feet in spots and deepening) that officials were considering the use of high lift equipment to extract vehicles.
It suggests rain in the I-95 corridor and snow from the mountains of West Virginia and Pennsylvania to southwestern Maine. Other models and ensemble versions will be examined this weekend as we narrow down the uncertainties associated with this fast-moving storm. Whatever the form of precipitation, you can count on another shot of cold air behind it. Lake-effect snow will be common as well.
I can see how slippery spots can develop from Philadelphia's northern and western suburbs on northeastward. The highest amounts of snow may be from Boston's western and northern suburbs on through Portsmouth, Portland and Augusta. Some spots could get 3-4 inches. Be ready for a slow commute tomorrow morning. If these problems develop, they could occur rather suddenly.