Cold fronts What are cold fronts A cold

Cold fronts

What are cold fronts? • A cold front is a boundary that exists, where cold air is on one side of the boundary and warmer air on the other side • We can identify or see cold fronts by a band of clouds, know as the “tail” of the cold front • In South Africa, cold fronts are not always intense. Some cold fronts are very intense and can cause lots of bad weather, while others are fairly weak and have very little effect on South Africa 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 2

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The depth of the atmosphere Height above the ground in kilometers 10 km 5 km 3 km Cold fronts mostly affect the lower part of the atmosphere Ground level 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 4

What happens to the cold air and the warm air? 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 5

How do we know a cold front is heading for South Africa? 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC-PRE-254. 1 6

Satellite imagery 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC-PRE-254. 1 7

We can watch the cold front approaching and developing 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 8

We continuously monitor how the front moves, where it goes and what cloud/weather is resulting form it 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 9

We use weather prediction models to see what systems are approaching South Africa 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 10

How do you normally know a cold front is expected? 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 11

SAWS Media release 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 12

What weather do we experience with cold fronts? • South Africa is a vast country, and each province will experience the passage of a cold front differently • Within each province, each region can also experience a cold front in a unique way, it would depend on your: Location Altitude Proximity to the coast The season 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 13

As an intense cold front moves through, this is what we can expect Gale force winds are possible along the coast where the cold front is passing 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 14

Gale force winds are possible along the coast where the cold front is passing 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 15

Gale force winds are possible along the coast where the cold front is passing 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 16

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What does all of this weather look and feel like in reality? 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 18

Rainfall and windy conditions 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 19

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Very cold minimum & maximum temperatures 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 21

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In Summary • Cold fronts are common for South Africa but they do not always cause bad weather • Expect temperatures to decrease/become colder as the cold front passes your city/region • The interior of South Africa is only affected if the cold front is very intense/strong • Expect rain along the coast, with cloudy and windy conditions • Snow is possible in extreme cases but not with every cold front 2021 -03 -08 Templ ref: PPT-ISO-colour. 001 Doc Ref no: RTC -PRE-254. 1 23