Bryan's look at the Weather: 1/23/12 Cold Air Damming!

Yes, you read that right, and no it is not cursing the cold air! What it is, is that a cold area of high pressure is forcing shallow layer colder air to move south. Cold air is more dense and will sink to the surface. However due to the stretch of mountains along the eastern states, the Appalachians, this cold air can get stuck as warmer air try's to move in. Below I have shown several examples.

This mornings surface weather map, and satellite. Showing a potent storm in the Great Lakes that brought severe weather to the south last night. If you notice the warm front though, it is caught up on the western side of the mountains and the cold high pressure is allowing colder air to drain down the eastern side (noted by the arrows) Also of note. Severe weather usually can occur in situations such as this in the region between the cold front and the warm front, known as the warm sector.

This can further be illustrated on this mornings temperature map.

Although I do not like the color scheme, the purples are colder air, and note how it flows down the east coast, where a bubble of warmer air moved northward into KY and TN and OH.

Events like this can cause colder air at the surface and allow the warmer air aloft which should be rain, to fall to the surface a freezing rain.

This will likely be the case here in New England today, as the cold air at the surface will be hard to displace and the warm air will try to work in. So any rain that may fall in the morning, may be freezing rain, which can also be influenced by the snow cover from 2 days ago.

Warmer air will try to work into New England today, and will reach the south coast with temperatures near 50, mid 40's in along the north coast, but in the valley areas where the cold air is more dense and will be hard to scour out temperatures will remain cool in the 30s to near 40.

Later today, the cold air will be mostly pushed out as the warm front approaches precipitation will be light in nature. However the strong cold front does approach, a line of heavy rain will move into MA by, 7 PM and reach the Boston area after 8 PM. A rumble of thunder is not out of the question with this line.