Level 3 is an official State of Emergency. At this level, a serious emergency or minor disaster has occurred or a situation is deteriorating rapidly and public warnings are being issued. The Tennessee Emergency Management Plan (TEMP) is activated and a state of emergency is automatically declared per TCA 58-2-107.

A significant snow event will move into the Middle Tennessee region on Friday. Here's how much snow the greater Nashville area can expect.

If the precipitation is just rain or just snow, the atmosphere is either greater than or less than 32°. When you add in a wintry mix — freezing rain or sleet — then one must evaluate the temperature at different levels of the atmosphere.

Snow is expected to begin mid-morning for East Tennessee cities such as Knoxville, Gatlinburg and Oneida, and in early afternoon for those further north, closer to the Virginia state line, according to the National Weather Service.

The storm will bring "widespread snow accumulations" with a mixture of sleet and freezing rain possible south of Interstate 40 with "light ice accumulation possible."

The Winter Storm Warning is in effect now across Middle Tennessee and Southern Kentucky. It started at midnight Friday and will last until 6 a.m. Saturday for Lincoln, Moore and Franklin Counties. The rest of Middle Tennessee and Southern Kentucky are under the warning that started at 3 a.