I consider myself to be a cyclone guru. Most people in Mauritius would agree with me. They also consider themselves to be cyclone gurus.
Today is November 15th, 2009, the official start date of the cyclone season, so I snuck in and updated this post. Our first cyclone of the season arrived on time. Early this morning Cyclone Anja was given her name. She has been hovering as a numbered storm near Diego Garcia for the last few days, but is now heading south south-west. Anja looks like she could threaten Rodrigues (an island to the east of Mauritius) and then head south. No cause for concern at this stage.
Cyclone Anja - 15 Nov 2009
Risk of cyclones exists from Spring to Autumn, with peak season in February.
Cyclone info for Dummies:
Warm seas cause cyclones. That is why they appear in the southern hemisphere in our summer and the northern hemisphere in theirs.
What is the difference between a Cyclone, a Hurricane, a Typhoon and a Tornado?
Cyclones in the Indian Ocean, Hurricanes in the Atlantic and Typhoons in the Pacific. Tornados? Twisters, usually found hurling cows and cars around the southern US. Nothing to do with this blog.
What happens?
A low pressure system forms over a warm bit of water, clouds form, then storms. These storms become bigger and combine. Winds in the storm cell begin to grow, the wind caused by the rotation of the earth starts spinning the clouds around (clockwise in the Southern Hemisphere and anti-clockwise in the Northern Hemisphere.
The air then behaves like water down a plug hole and the storm (low pressure system) draws ever increasingly powerful winds spinning in at right angles (cariolus effect, I think) to the centre of the system. It also draws more water vapour into the system. Soon you have this massive lump of spinning storm that wanders around the sea being guided by the air moved by the spinning earth, nudged by high pressure ridges, and chipped away by wind shear, until it hits land. The cyclone then runs out of water vapour to suck into the system, and starts losing power, until it fades away. Or it gets pushed into cooler seas and collapses by itself.
If you want to track a cyclone
If you want to track a cyclone and don't have the internet to do this, all you need is a barometer and your left arm. For the smart asses out there who are sniggering at the absence of logic in the previous sentence, let me just inform you that when a cyclone gets close, the lights go out. Internet will be patchy at best, and subject to battery life or generators. You will also have no radio, or TV. A barometer and a left arm can then be quite appreciated. Read on...
As the barometer falls to around 1000 Mb (millibars) and then below, the wind will grow. Clouds and rain will probably be significant weather features at this time.
When the winds are gusting at a fair rate, turn your face into the wind (so that it blows your hair back), and point out your left arm sideways (away from your left ear- but don't look at your finger or you will end up pointing behind you!). Your finger will be aiming at the cylcone. As the storm tracks around you, the wind direction will change, the pressure will drop and you will be able to work out the rough direction of the cyclone. Take care not to get hit by a flying branch or piece of corrugated iron. Winds of 270 k's per hour have been recorded. A solid object flying at that speed is likely to go straight through you.
If the wind suddenly stops and everything is calm, you are in the eye. Don't go fishing. In a short period of time the storm will return with a vengeance. When you notice the barometer going back up, you will know the storm has passed and the weather will be improving.
Here are the storm tracks for last season (2008/2009) compliments of Meteo France - Reunion
Visit them on: http://www.meteo.fr/temps/domtom/La_Reunion/#
You will notice that there are ten tracks above, because there were ten 'named' storms. Also notice how lucky we were in Mauritius.
Once a storm is named, it becomes official and then applies to the small print of your insurance policies. Earlier in this blog, I referred to numbered storms. These don't get included. Cyclones all start their life as numbered storms and then as they get big and strong enough, they get names in alphabetical order as the year progresses.
Our list of names for this year is:
Anja, Bongani, Cleo, David, Edzani, Fami, Gelane, Hubert, Imani, Joel, Kanja, Lunda, Mohono, Nigel, Olympe, Pamela, Quentin, Rahim, Savana, Themba, Uyapo, Viviane, Walter, Xangy, Yemurai, Zanele.
The countries in the region all have a chance to propose names for cyclones, so if you ever want to have one named after you, become friends with someone who works in the met office of any country in our region (South Western Indian Ocean).
The met office predicts ten named storms for this season. This is an average and is not news.
Mauritius is due a big cyclone.
We haven't had a serious one since 1994 (Hollanda) and it seems that a major cyclone hits Mauritius every ten to fifteen years. Oh Oh. 2010-1994=16 years.
But being the eternal optimist, and armed with my own theory of how global warming has affected cyclonic behaviour, I will predict that we will have a number of bad weather days with clouds and lots of rain but no damage, as cyclones form over us, to move on and descend on poor Madagascar, as well as the east coast of Africa from Durban to Beira.
What is my theory?
Cyclones are like Goldilocks, and like forming in water that is not too hot, and not too cold.
This perfect temperature has been moving slowly southwards as global warming heats the oceans. The optimum place for formation of cyclones has moved from somewhere near Diego Garcia (1000 odd kilometres north north east of us) in a south westerly direction towards us. More and more cyclones are being formed further and further south west. This bodes well for us as we may miss more and more. Bad news for the dudes in Madagascar and South Eastern Africa. The counter argument is that as the sea warms we will simply get more cyclones. I don't like this argument, it makes me uncomfortable!
What facts do I have to support this theory?
OK, the facts I have are unlikely to put me on any Nobel Prize Winner's list, but here they are:
Using Meteo France's past cyclone maps of cyclone tracks (see image above) I looked at all their maps, from the season starting in 2003, to the one that ended this year. That's only five maps. I then counted all the named cyclones that made it to the Mozambique Channel each season. Here are my results:
2003 3/10 (season starting 2003, 3 named cyclones out of 10)
2004 2/10
2005 1/6
2006 5 / 15
2007 4/14
2008 3/10
Not conclusive, but certainly not getting any less.
I then looked at the number of cyclones each year that formed below -10 degrees south (roughly where Diego-Garcia Island is).
Here are my results:
2003 5/10 (season starting 2003, named cyclones formed south of -10 degrees south)
2004 1/10
2005 3/6
2006 9/15
2007 9/15
2008 7/10 This shows that a growing percentage of cyclones are forming further south.
Now any weather man will tell you that you can't detect a weather trend over such a short period of time. So let's keep watching, and see if I am wrong.
For the latest cyclone bulletin, sat photo or storm tracks for this season, go to
frontfin.com and click on weather links.