Southerly Buster cools NSW coast
Josh Fisher,
Monday January 26, 2015 - 07:33 AEDT
A Southerly Buster that traveled along the New South Wales coast on Sunday brought a sudden burst of winds and relief from the hot temperatures. Unfortunately for those looking to hit the beach this Australia day, the change has brought some gloomier weather.
To be classified as a 'Southerly Buster' the change must produce southerly wind gusts in excess of 54km/h and cause temperatures to drop by at least five degrees in three hours. While this is the base criteria for the phenomenon to be defined, the gusts and temperature drops can be much more dramatic.
Southerly Busters typically occur along the NSW coast around five times a year and are most frequently observed between October and February.
Their intensity is dependent on the contrasting temperatures ahead and behind the change and the depth of the cooler layer of air. The process is further assisted by the presence of the Great Dividing Range, which creates a channeling effect as the southerly winds move along the coast.
The southerly that pushed along the NSW coast during Sunday did meet the criteria to be defined as a Southerly Buster, however was not a particularly strong event. These changes can and have generated winds in excess of 100km/h in the past and have brought temperature drops of 10-15 degrees in as much time. Yesterday's event was certainly noticeable but winds only just exceeded the threshold.
The southerly had reached Albion Park along the Illawarra coast just after 5:30pm on Sunday, producing wind gusts of 61km/h with the temperature dropping five degrees (34 to 29 degrees) in just nine minutes. The temperature then continued to plummet through the evening.
The change pushed through Sydney just after 7pm, bringing a burst of winds to 59km/h and allowing temperatures to drop by five degrees in just 30 minutes. The southerly came as relief for many and made for a more comfortable night of sleep.
For today, temperatures through Sydney will remain more than 10 degrees below Sunday's maximums, only climbing into the low-to-mid twenties. Cloud cover will linger through the day with scattered showers dampening the many barbeques that would have been planned.
- Weatherzone
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2015