Severe Thunderstorm Warning Service in NSW and the ACT

The Meteorological Act of 1955 lists one the functions of the Bureau of Meteorology as:

"the issue of warnings of gales, storms and other weather conditions likely to endanger life or property"

Throughout the year, the Bureau of Meteorology operates a (broad-based) Severe Thunderstorm Warning Service for the whole of NSW and the ACT, supplemented by a (detailed) Severe Thunderstorm Warning Service for the Greater Sydney area. This service is enhanced with additional staff during the "severe thunderstorm season", that usually runs from September through to April. A brief description of the service follows:

  • Severe Thunderstorm Warnings (broad-based) are issued as an alert to the public, emergency services and other organisations that severe thunderstorms are likely to develop, or extend into, a specified area over the next few hours. They are based on broad areas such as the Bureau’s weather forecast districts and have a validity time up to 6 hours (but are usually updated within 3 hours). Warnings will describe the most likely weather phenomena (i.e. large hail, strong winds, tornadoes or torrential rain) that will accompany the storms. All warnings carry action statements that say what you can do to minimise the danger to yourself and those around you whilst the warning is current. (sample broad-based Warning)
  • Severe Thunderstorm Warnings - Greater Metropolitan (detailed) provide more specific information on individual severe thunderstorms when they are within range of Sydney’s weather-watch radar. Warnings are provided for the Greater Metropolitan Area, roughly bounded by Wyong, Blackheath, Moss Vale and Kiama. This area contains about two thirds of the State's population. Warnings have duration of up to 90 minutes (but are usually updated every 30 minutes) and also carry action statements on what you can do during that time. (sample detailed Warning)

More details on Severe Thunderstorm Warnings , including graphical warnings. 

Severe Thunderstorm Warnings are sent direct to most radio and television stations in NSW for immediate broadcast. The latest Warnings are also available from the Bureau of Meteorology's World Wide Web site and Weather by Fax services. 

What you can do on hearing a Severe Thunderstorm Warning

When you hear a Severe Thunderstorm Warning broadcast for your area, storms may not yet be occurring. This is no reason to be complacent. Take notice of the warning, and treat all thunderstorms that develop during this period with caution.

State Emergency Service action statements are an important part of the warning message as they highlight actions people can take to minimise the risk of property damage, injury and death. The action statements vary according to the type of storm expected as follows:

If strong winds or hail are forecast, people should:

  • put vehicles under cover
  • beware of fallen trees and power lines

If very heavy rain and flash flooding are forecast, people should:

  • keep away from creeks and drains as you may be swept away
  • avoid driving through water of unknown depth

If tornadoes are forecast, people should:

  • shelter in the strongest part of a building (e.g. bathroom or basement)

During all severe thunderstorms, people should:

  • move indoors away from windows
  • take extreme care when driving
  • avoid using the telephone

We must be aware of the dangers of Severe Thunderstorms. As northern Australia prepares for the tropical cyclone season, people in NSW and ACT should be prepared for the "Severe Thunderstorm Season".

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