Weather forecasting

[Synoptic weather map weather forecatsing]

Climatology weather forecasting
General weather in summerInterior
· hot
· moist
· with thunder showers
Exterior
· East coast
o Humid
o Hot
o Weather temperature doesn’t vary between night and day
o Windy
· West coast
o Dry
o Windy


Discussion of weather systems/ patterns
· Synoptic weather mapo Shows the weather at a particular time and place
o Isobars show the air pressure
o A synoptic weather map will also show weather patterns, and weather systems

· Isobarso Is a line joining places with the same air pressure

· Mid latitude cycloneso Has  cold and warm front
o Low pressure system
o Moves from South West to North East to South East (Southern Hemisphere)
o Location 30 - 60° Latitude
o Life span of 5 – 6 days
o Warm front brings warm weather
o Cold front brings cold air
o Comes in families (family of depressions)

· Tropical cycloneso Comes in late summer early winter
o Develops between 5-30° Latitude (Latitude are the imaginary lines that run vertically along the earth, they run parallel to each other)
o It moves from North East to South West to East in direction
o Bring heat
o Only occur over oceans with a minimum temperature of 27°C

· Coastal lowo Small and weak
o Move South East along the coast
o Wind is hot and dry – is known as berg wind
o In front of the coastal low you get an offshore flow (wind from the land moving towards the sea)
o Behind a coastal low you get an on-shore flow (wind from the sea moving towards the land.
o Cool air, drizzle




· Blocking higho Often situated south of South Africa
o Forced east ward moving weather systems (mid latitude cyclones and coastal lows) to the south, away from South Africa
o Has a North South axis
o Usually occur in summer

· Isobaric patterns
o There are patterns shown by isobars that we see on the map
o There are 3 categories that fall under this heading

§ Low pressure trough· Is when the isobars bend away (southwards) from a low pressure cell
· The low pressure has to be between 2 high pressures, otherwise it is not a low pressure trough
· Rain may follow

§ High pressure ridge
· Is when the isobars bend away from a high pressure cell (eastward/ westward)
· The high pressure has to be between two low pressures.
· If air is coming from the South Atlantic ocean it may bring cool dry weather to South Africa.
· If the air is coming from the Indian ocean it will bring humidity and hot weather
§ Saddle area
· Is an area with constant or the same pressure.
· There are no isobars in this area.
· There is no wind in this area

· South Atlantic high
o Part of the pressure systems
o Situated in the west of South Africa

· South Indian high
o Situated to the east of South Africa
o In the summer it is further south
o It brings moisture into South Africa

· Kalahari higho Over South Africa in the winter
o Has strong descending air, which leads to clear skies and moderate air
o Heating in summer makes it disappear

Making our prediction using the synoptic weather map