The Cone of Uncertainty

I'm sorry, I know it looks like I've become obsessed with the weather but a new hurricane is threatening the Gulf coast and it gives me a an opportunity to emphasise one of the points I made last time. Those of you who follow the cricket (and TMS in particular) will have heard and smiled at the phrase 'The Corridor of Uncertainty' which refers to the sort of ball which leaves a batsman in two minds as to whether they should waft the bat at it or leave it well alone.

Here in Hurricane Land we have a very similar situation with the Cone of Uncertainty - you hear this on the weather forecast and can't help but give a wry smile. It means nobody has a clue where the storm is going.

There are problems with tracking a major storm over four or five days - it can cover hundreds and hundreds of miles and turn unexpectedly. So you get these really helpful diagrams like this one:



The green swirl is where Gustav is today. The red ones show the probable track until Monday. Okay, so it's heading for Louisiana you might think. But the large pale circle around the swirl indicate that the centre of the storm could be anywhere within this area. When you draw it like this you get the Cone of Uncertainty beloved of Gulf meteorologists:



Gustav, a category 3 hurricane, could end up anywhere inside the white line; landfall might take place towards the Texas/Mexico border - or in Florida. But these diagrams still have a sober central line that draws the eye (ours as well as Gustav's) towards Louisiana. So, it's still likely to go that way isn't it? Well.. maybe, but there's another map, which compares computer projections by various global weather organisations. Here it is:



So, there's a vague consensus towards it being Louisiana that gets the worst of it, three years after Katrina. But the Met Office's prediction (the white line) scoots off towards Mexico. And the yellow one is ploughing straight through my front room by the looks of things.

As I mentioned last time, the anticipation is the worst bit (so far) and the inconvenient situation is that we all have to be ready, because by the time we know for certain that it is coming our way it will be too late to prepare.

Now I formally promise that I won't do this every time a storm starts heading my way, but this is the busiest week of hurricane season: Hanna is already on her way to Puerto Rico and two more systems are beginning to organise in the Atlantic. So forgive me if it looks like I'm using these notes as some group therapy session to help me with my Limey culture shock.