Quiet start to cyclone season
Ben Domensino,
Tuesday November 22, 2016 - 15:26 AEDT
The first month of Australia's tropical cyclone season looks like it will end without any systems being named in the Australian region.
November is typically the quietest month of the season and often goes by without seeing a single cyclone. There have only been four November cyclones in our region during the last decade, Alessia (2013), Anika (2008), Guba (2007) and Lee-Ariel (2007).
This month is living up to expectations, with forecast models showing little activity during the next eight days.
A low pressure system over the Coral Sea gained some attention from cyclone-watchers this week, although it was fell short of cyclone status.
So why do some lows turn into cyclones and others don't? It is the cyclone season after all.
There is a fairly narrow set of conditions required for cyclone development, which are only found in some parts of our planet.
A low pressure system will only become a tropical cyclone if:
- The sea surface temperature is at least 26.5 degrees Celsius
- The atmosphere is unstable enough, by becoming sufficiently cooler with height
- Vertical wind shear is low enough, meaning winds don't increase in speed too much with height
The Coral Sea low is spinning over waters that are too cool and in an environment with too much wind shear for it to become a cyclone.
As we progress further into the season, water surrounding Australia will become warmer and rivers of strong winds in the atmosphere called jet streams will shift position. This will allow conditions to become more conducive to cyclone formation in our tropics.
The Australian region should see more more cyclones than last season, which was the quietest on record for our area.
If you live in a cyclone-prone part of Australia, prepare now for the more active part of the season ahead by:
- Trimming tree tops and branches around your home
- Clear loose material around your home that could be blown around easily by strong winds
- Know your nearest safe high ground in case of a storm surge
- Prepare an emergency kit
- Have a list of emergency numbers in display
More information about cyclone safety can be found here: http://www.bom.gov.au/cyclone/about/checklist.shtml
- Weatherzone
© Weatherzone
2016