Map is color coded and updated by the National Weather Service.
NUMBERED BOXES are tornado (red) and severe thunderstorm watches (light blue).

WATCH = Good potential exists in defined area, so be ready in case a warning is issued.
WARNING = Potential is becoming reality. You should already be prepared.
ADVISORY Hazardous weather is occurring or is about to occur and may require special preparation, but is not serious enough to warrant a warning.

DEFINITIONS TUTORIAL - Watches, warnings, and advisories are issued for these (and more.)

SEVERE WEATHER Tornadoes are spinning columns of air born from severe thunderstorms. The strongest tornadoes can be a quarter-mile wide with winds of 300 mph, destroying (or relocating) everything in their path. A severe thunderstorm is one that has damaging wind gusts and/or large, damaging hail.

FLOODS Sudden heavy rain may produce flash floods, which are extremely localized and turn dry areas into flooded areas within minutes. Generalized Floods (or river floods) usually take longer to develop but last longer. Coastal floods are tide-related, and usually happen when storms and/or astronomical factors create ocean waves that come into developed areas on shore. Floods don't need to be deep to create severe damage - if the water flows underground, it can undermine roads and buildings.

COLD WEATHER EVENTS A winter storm is defined as any combination of snowfall, sleet, or ice capable of disrupting life or commerce (exact amount varies by location.) An ice storm warning is issued when ice (glaze) coatings will be in excess of a quarter-inch in any part of the country. For less than 1/4 inch of ice, freezing rain advisories are issued. A blizzard has winds in excess of 35 mph sustained over at least 3 hours, with snow (falling or blowing) reducing visibility to under a quarter-mile the entire time.

TROPICAL WEATHER Tropical storms and hurricanes differ from other types of storms that come from the tropics. They require very specific conditions in order to form and maintain strength, and their structure looks like a pinwheel when fully developed. Tropical storms have sustained winds of 35 to 73 mph and get names from a pre-decided, alphabetical-order list that changes each year. When the sustained wind reaches 74 mph, the tropical storm is called a hurricane. It retains its name until it has fully dissappeared. Tropical storms and hurricanes often cause severe thunderstorms, tornadoes, and floods of all types, in addition to their sustained wind. They also have a storm surge, which is a rising of ocean water near the center (eye) of the storm that floods everything under its height when it comes ashore. The height of the storm surge depends on the strength of the storm. Ocean waves and storm swells ride on top of the storm surge, adding to the total flood height.

At any time of year, warnings and advisories are also issued for non-thunderstorm winds that are strong enough to threaten life, property, or commerce.