A synoptic chart (also called a weather map) is a map that shows a summary of what is happening in the atmosphere over a large area (like a country or region) at a specific point in time.

It helps meteorologists (weather scientists) visualise patterns of air pressure, wind, and weather systems like high and low-pressure areas, cold fronts, and rain zones.

Isobars are lines drawn on a synoptic chart which connect places of equal air pressure. Every point on an isobar has the same pressure. Air pressure is measured in hectopascals (hPa). You might think of air pressure as the weight of the air as it pushes down on the earth’s surface.

 The closer the lines (isobars) are the stronger the wind will be. By contrast, where isobars are drawn widely spaced, there will be gentle winds.

Isobars are lines drawn on a synoptic chart which connect places of equal air pressure. Every point on an isobar has the same pressure. Air pressure is measured in hectopascals (hPa). You might think of air pressure as the weight of the air as it pushes down on the earth’s surface.

The closer the lines (isobars) are the stronger the wind will be. By contrast, where isobars are drawn widely spaced, there will be gentle winds.

High Pressure Systems are areas of high pressure (sinking air) they bring happy weather. This is why you might hear them being called Happy Highs by your teacher… and almost noone else in the world.

Example of the weather High Pressure Systems (Happy Highs) bring:

●      increase in temperatures

●      decrease in wind speed

●      decrease chance of rain

How do you know you are looking at a High Pressure System?

They have:

●      widely spaced isobars,

●      A big “H” or the word “High” written on them (but this isn’t usual on a synoptic chart)

●      values above 1000hPa which increase in pressure towards the centre.

Low Pressure Systems are areas of low pressure (rising air) they bring lousy weather. This is why you might hear them being called Lousy Lows by your teacher… and almost noone else in the world.

Example of the weather Low Pressure Systems (Lousy Lows) bring:

●      decrease in temperatures

●      increase in wind speed

●      increase chance of rain

How do you know you are looking at a High Pressure System?

They have:

●      closely spaced isobars,

●      A big “L” or the word “Low” written on them (but this isn’t usual on a synoptic chart)

• values around or below 1000hPa which decrease in pressure towards the centre. 

Cold Fronts are the front of a moving mass of cold air. The diagram below shows a Cold Front as a line with arrows along it. The cold air mass behind this line moves in the direction that the arrows point.

They bring conditions similar to a Lousy Low:

●      decrease in temperatures

●      increase in wind speed

●      increase chance of rain

Plus one more:

• • a change wind direction 

Wind indicators are a symbol that show us the wind strength and the direction the wind comes from.

A wind indicator is made up of 3 components:

●      A location dot

●      A wind direction arm (pointing away from the dot)

●      Wind speed fingers (on the end of the arm)

The direction the arm points away from a location dot is the name we give the wind. In the example below the direction arm points North-East away from the dot. So we would name this wind a North-Easterly.The number of fingers on the arm let you know how strong the wind is. There will be a key on a synoptic chart to tell you what the fingers mean, but a general rule is: the more fingers, the stronger the wind. An example of a wind speed key is shown below.

In Australia weather features generally move from west to east. So if you want to know what the weather might be like tomorrow or in a fews days in Sydney, you might look at the weather in a location west of us.

For example, weather events over central NSW will likely be over Sydney in the next 24 hours

A weather feature over Perth e.g. a Low will take about 3 days to move east and start to influence Sydney.