NWS - Warnings, Watches, Advisories, and Statements defined

What the NWS Warnings, Watches, Advisories, and Statements mean to you.

1. WARNINGS - The hazard (tornado, flash flood, etc) is imminent. The probability of occurrence is extremely high. Warnings are issued based on eyewitness reports or clear signatures from remote sensing devices such as radar and satellite. Lead-time for thunderstorm type events is generally 30 minutes or less. Lead-time for hurricanes, river floods, and winter storms can be 6 to 18 hours.

2. WATCHES - Meteorologists have determined that conditions appear right for the development of the hazard. Probability of occurrence is greater than 60% in the watch area. Watches generally cover larger areas than warnings. In the case of thunderstorms, less than 30% of the watch area may experience the hazard. However, with larger storms such as hurricanes and winter storms, the entire watch area may be affected. Severe thunderstorm and tornado watches are usually issued 1 to 2 hours before the event begins. With flash floods, it can be 3 to 12 hours. For hurricane, river flood, and winter storm watches, lead-times are usually 12 to 36 hours.

3. ADVISORIES - An advisory is issued for weather that is expected to be a disruption to the normal routine and an inconvenience, but it is not expected to be life-threatening. Advisories are issued for 1 to 3 inches of snow, dense fog, minor street flooding, etc. The time frame is similar to that of a warning.

4. STATEMENTS - statements are issued to update current weather situations or highlight significant changes to come. Statements are also used to explain why watches, advisories, or warnings have been issued. Three special types of statements are ...

a) "Outlooks" or "Potential " Statements - During the warm season, the NWS Forecast Office issues "Thunderstorm Potential Statements" each morning discussing where and if storms will develop that afternoon and how intense they may be. When a winter storm may develop in the next 2 to 4 days, "Winter Storm Potential Statements" are issued. Outlooks may also be issued for possible heavy rain and flood events. The National Hurricane Center issues "Tropical Outlooks" for the potential for tropical storm and hurricane development. The National Severe Storms Forecast Center issues special statements when there is the potential for a severe thunderstorm or tornado outbreak.

b) Short-Term Forecasts - These statements discuss the short-range forecasts for the next 1 to 6 hours. During active weather, these statements may be issued hourly.

c) Public Information Statements - These statements provide information of special interest such as a summary of recent records set, snowfall, weather safety information, special activities (weather related) that may be occurring, etc.


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