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Introduction
My name is Shane Rowe and I would like to quickly introduce
myself and this special mini report.
I have brought this information together to help aussie weather
watchers increase their understanding of the Australian weather
map.
You will find here all the information you need to get a basic
understanding of the Australian weather map.
I trust you will find this information useful – please feel free to
contact me should you need any further assistance.
Kindest Regards,
Shane
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A weather map is simply a display of air pressure at the
surface of the earth, which is measured in millibars and
shown on a barometer.
The lines on a weather map are called isobars. These
isobars connect to other areas that have the same air
pressure.
The letter "L" represents an area of Low air pressure, while
the letter "H" represents an area of high air pressure.
Areas of low pressure are usually associated with strong
winds, rain and thunderstorms.
While areas of high pressure are usually associated with
light winds and clear skies. Frosts and fogs over the
southern inland regions during the winter months are also
associated with high pressure systems.
The dotted blue line on a weather map is a low pressure
trough, this is an area of unstable air usually to the north
of high pressure systems that often produce
thunderstorms.
The blue lines with triangles are cold fronts which are
usually located to the south of high pressure systems and
are linked to low pressure systems in the southern ocean.
A cold front is basically where a cold airmass meets a
warmer airmass which often produce gusty winds,
showers, thunderstorms and a drop in temperature as it
moves through.
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In the summer months, the high pressure systems move
further south providing more settled conditions in the
south.
At the same time this allows very moist unstable northwest
winds associated with the monsoon to move over the
tropical parts of Australia which provides heavy rain and
thunderstorms to northern areas, this also includes tropical
cyclones which are very intense low pressure systems that
form over warm oceans.
Below is what a typical summer weather map looks like.
It shows two high pressure systems over the oceans to the
south of the country with hot northerly winds blowing down
into South Australia ahead of a low pressure trough which
is the blue dotted line. Tropical Cyclone Dot is sitting off
the Queensland coast with heavy rain and gales out to sea.
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In the winter months the high pressure systems move
further north which then results in more settled dry
weather across northern Australia.
Southern Australia then is under the influence of westerly
winds with embedded cold fronts that link to intense low
pressure systems in the southern ocean which provide
regular bursts of cold, wet and windy weather and snow to
the mountains.
Below is what a typical winter weather map looks like.
It shows two high pressure systems bringing dry settled
conditions to the inland and northern Australia. While a
cold front with strong winds and showers is moving
through Victoria and Tasmania and another cold front is
approaching Western Australia.
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In the southern hemisphere which includes the Australian
region, the air moves clockwise around low pressure
systems and anti-clockwise around high pressure systems.
This provides a good indication of the direction that the
wind would be coming from for any location on the map.
In general,if the wind direction is coming off the ocean the
air mass would be more moist, however if the wind
direction is blowing from the land, the air mass would be
drier.
The closer the isobars are on a weather map, the stronger
the winds would be.
In general the lines or isobars around areas of low pressure
are closer together which indicates strong winds, while the
isobars around areas of high pressure are spaced further
apart indicating light winds.
In summary, by looking at a weather map, it gives a good
indication of what number the air pressure would be in
millibars in your location, which would be displayed on your
barometer.
Also at a glance you can understand the type of air mass
that is affecting a location by the wind direction and the
strength of the wind.
Combine that with the time of year that it is and the
amount of cloud that is around which is shown on a
satellite photo, it provides a general understanding of what
the temperatures would be.
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