While we experience many thunderstorms, some more intense thunderstorms are referred to as severe thunderstorms. Severe thunderstorms can cause significant localised damage by action of damaging wind gusts, large hail, tornadoes or flash flooding. Warnings are issued by the Bureau to alert communities of the threat of these more dangerous thunderstorms.
What is a severe thunderstorm?
Check the Education Material page.
When is a Severe Thunderstorm Warning Issued?
- A Severe Thunderstorm Warning is issued when a severe thunderstorm is reported, or there is strong evidence of a severe thunderstorm, and it is expected to persist
- Also, Severe Thunderstorm Warning is issued when existing thunderstorms are likely to develop into a severe thunderstorm
Severe thunderstorms can be quite localised and develop quite quickly. The exact location of severe thunderstorms can be hard to predict. The warnings are usually issued without much lead-time before the event. To try and issue warnings with a greater lead-time would lead to a flood of false alarms, thus rendering the service ineffective.
DETAILED and BROAD-BASED Warnings
The Bureau maintains a network of weather watch radars which are the prime source of information that can be used to maintain an effective severe thunderstorm warning service. The radar networks are focused on the main population centres. In these locations, the Bureau provides a more detailed severe thunderstorm warning service to cater for the densely populated cities and surrounding areas, particularly in the east where the worst severe storms occur.Severe thunderstorm warnings are issued for other parts of Australia, but these will usually be less detailed.
How often is a Severe Thunderstorm Warning issued?
While the threat remains, a severe thunderstorm warning will usually be issued every three hours, however the more detailed city warnings may be issued every 30-60 minutes.
What information is included in the Severe Thunderstorm Warning?
Severe Thunderstorm Warnings can contain the following information:
|Standard Emergency Warning Signal (SEWS) - only sounded for extreme events||Very few||Very few|
|Expected phenomena (Large hail, Damaging winds, etc)||All||All|
|Time of issue||All||All|
|Description of prevailing weather situation (where necessary)||Few||Few|
|Broad Description of Threat||Some||All|
|Detailed radar information indicating severe thunderstorm locations and expected paths||All||Some|
|Information on recent storm damage||Some||Few|
|Action Statements (guides on what to do and not to do - provided by local Emergency Service organisations)||All||All|
|Expected issue time for next warning (or last warning advice)||All||All|
Who is the target audience of Severe Thunderstorm Warnings?
All communities in the threat zone.
Where are Severe Thunderstorm Warnings Issued?
Severe Thunderstorm Warnings are issued by Regional Offices of the Bureau of Meteorology in the capital city of the affected State/Territory, with the exception that warnings for the ACT are issued from Sydney.
- Detailed Warning
- Broad-Based Warning
- Graphical Severe Thunderstorm Warnings for:
Note that other specialised products are provided to key stakeholders - like emergency service organisations. These generally provide detailed technical information to assist these organisations in planning disaster mitigation strategies.
Storm Spotters Link
For information about storm spotters and how you could become a storm spotter check the storm spotters page.