The official source for weather information is the National Weather Service. Go to Weather.gov and click on your location on the national map — that will take you to your local NWS office. The NWS has several advisories it will send out when winter weather threatens a region. The NWS issues watches for potential events out to 48 hours in advance. A warning implies an imminent or occurring event.
Winter Storm Watch/Warning: A more general advisory for heavy snow, damaging ice, or a combination of both with strong winds.
Heavy snow warning: A snowfall of 4 inches in 12 hours, or 6 inches in 24 hours; snowfall criteria will vary with region. The type of snow will not normally be addressed in the forecast. With temperatures near freezing, you can expect a wetter, heavier snow.
For freezing rain, the NWS can send out a Freezing Rain Advisory if accumulation less than 0.25 inches is expected. For expected damaging ice accumulations of over 0.25 inches, the NWS will send out a full-fledged Ice Storm Warning.
For winter strong wind events, the NWS can issue High Wind Watches/ Warnings. By the NWS definition, this means that potentially damaging winds of 40 mph or greater, or wind gusts of 58 mph, can be expected for at least one hour.
In terms of damaging winter cold in the typically warmer southern states, the NWS will issue a Freeze Watch/ Warning. This means that widespread temperatures below freezing are expected. Even worse conditions with temperatures at or below 28 degrees Fahrenheit would be warned with a Hard Freeze Warning. In comparison, a Frost Advisory would be sent out for air temperatures in the mid-30s, but with local surface temperatures at or below freezing.
Read more: Examining Winter Weather Worries for Trees