Thanks for sending your email to Severe Weather Center 9. Typically the winds that keep our weather warm are from the south and southwest. Warm temperatures that reside across the deep south and tropics will travel up to us on these winds. Now we can also get warmer weather from a different direction, the west or northwest. Now you would think that winds flowing down from the mountains would cool us down. But that is not usually the case, here's why.

When the winds blow down the hillsides of the Appalachians, the air compresses (or squeezes together) and warms. It warms due to the laws of physics. When air is compressed it warms up because the air molecules bump into each other faster, causing more friction and the result is heat. We call these winds downsloping winds and they can really warm us up several degrees.

As far as cooler weather is concerned, we mainly get this from the north and northeast. Sometimes from the east or southeast as well but to a lesser degree. The coldest weather we get comes from a north or northeast wind. Many times a cold front will arrive and the winds immediately behind it will flow from the northwest, causing our weather to either stay the same or warm up (due to the downslope.) But, once the winds shift to the north or northeast the next day, that colder air behind the front is then allowed to move into the Carolinas. In the fall or winter we get what is called cold air damming. This happens when persistent northeast winds push cooler and more moist air up against the mountains. This cooler air gets dammed against the hillsides and can last for days.