Arrangements for Flood Warning Services in Victoria
A4. Flood Warning Categories &
Current definitions are:
Causes inconvenience. Low lying areas next to watercourses
are inundated requiring the removal of stock and equipment.
Minor roads may be closed and low level bridges submerged.
In addition to the above, may require the evacuation of some
houses. Main traffic routes may be covered. The area of
inundation is substantial in rural areas.
Major Flooding. In
addition to the above, causes inundation of extensive rural
areas and appreciable urban areas. Properties and towns are
likely to be isolated and major traffic routes likely to be
closed. Numerous evacuations may be required.
Definitions for Flood
Official notices for flooding come in three main types. These
are either a Flood Advice, Flood Warning or notice of
thunderstorms. The types are:
Advice issued by the Bureau of Meteorology to media, agencies
and the public. The message contains specific weather
information and limited comment on potential flood impacts.
The main purpose of the advice is to inform the public and
agencies that a weather situation is developing which could
result in flooding.
Warning issued by the Bureau of Meteorology or Local
Government (especially for flash flooding) to media, agencies
and the public. The message usually contains details that
flooding is about to occur or is happening, predictions,
expected impact, and can include what actions should be
taken. It also contains detail on when the warning was issued
and when the next update can be expected. Other tailored
information can also be included such as operation of weirs,
lochs, comparison to historic events, contact numbers for
Some warnings issued by the Bureau of Meteorology are in
consultation with water authorities where the authority's
activities are inherently a part of the flood warning
service. Melbourne Water prepares flood warnings for Greater
Melbourne for issue through the Bureau.
A severe thunderstorm is defined as having one or more of the
Hail with diameter equal to or greater than 2 cm
Wind gusts equal to or greater than 90 km/hr (48kt)
Heavy rain leading to flash flooding
In the case of thunderstorms which may cause flash or
localised flooding the Bureau of Meteorology issues the
Advice. Advice valid for up to 6 hours, issued to
the media and appropriate agencies whenever a severe
thunderstorm has been identified or there are strong
indications that severe thunderstorms will develop. A severe
thunderstorm advice is used for weather based districts
outside the Greater Melbourne area.
These districts are North Mallee, South Mallee, North
Wimmera, South Wimmera, Lower North, Upper North, Lower
Northeast, Upper Northeast, East Gippsland, West Gippsland,
East Central, West Central, North Central, Western Plains,
and West Coast.
Warning. Warning which covers the Greater
Melbourne area and is valid for up to 2 hours. It is issued
to the media and appropriate agencies whenever a severe
thunderstorm has been observed in or close to the
Metropolitan area (including Geelong), or when there is radar
evidence for a severe thunderstorm or when there is
significant evidence that severe storms are about to develop.
Chart. Chart issued routinely at 11:30 am during
the convective season from October to April regardless of
whether severe weather is expected or not. This chart is sent
to emergency management agencies (VICSES, police, fire
authorities), public utilities, and local and interstate
Bureau of Meteorology offices.
It shows parts of the state where a watch is maintained for
severe weather, and severe and non-severe thunderstorms. For
other times of the year, this chart is only issued when
severe weather is observed or expected.
Severe Thunderstorm Warning
Chart. Chart issued showing the location and
expected movement of severe thunderstorms with the Greater
Melbourne area. This is issued to VICSES, Police, Melbourne
Water and other utilities whenever a severe thunderstorm
warning has been issued.