Love it or loathe it, the early stages of Spring can provide some dramatic contrasts.

Take this week as an example. So far, it's been largely a story of sunshine and showers across much of the UK. With cool winds from the north west, and a strengthening sun, it doesn't take much warming of the ground before the cloud bubbles up and the showers begin.

So you may leave the house on a chilly and sunny morning, but it doesn't take long for the temperature to rise. Then, as you decide it's worth doing without a coat, the skies rapidly darken, there's a clap of thunder and the rain pours down.

More often than not, just a short while after, the skies clear again and once more you are bathed in glorious sunshine. This is where the job of being a forecaster becomes a very difficult one. It's not as much the forecasting of showers, but trying to explain the whole concept of a shower.

As public forecasters, we tend to use the term 'showers' to describe short bursts of rain (heavy or light) that generally last less than an hour. On a rainfall radar chart these tend to show up as bright, individual cells of rainfall, but this is where the problem arises.

We as forecasters often think in a very spatial manner, due to the fact that we are forecasting for a very large area. To an individual though, confined to a small area, the reality of showers can be much different. Whereas one person can be hit by shower after shower, making the day a rather wet one, another person just a few miles away can be bathed in glorious sunshine.

Showers can therefore impact on people in very different ways. If the showers are particularly heavy and frequent localised flooding, or worse, can occur. This is due to the sheer volume of water that can fall from the sky in such a short space of time.

So far this week this week, there has been no significant disruption caused by showers in the UK, but showers during the past couple of days in other parts of the world have had more of an impact.

In New Zealand, cold southerly winds brought shower after shower to Christchurch. 25 mm (1 inch) of rain fell in 24 hours - half their monthly average.

In the US, heavy thunderstorms in Texas continued, with the town of Brownsville receiving 35 mm (1.4 inches) of rain in just six hours. This is only 8 mm (0.3 inches) short of their monthly average.

Perhaps more extreme, are the thunderstorms that have been rumbling around in Argentina. In the space of just 24 hours, 110 mm (4.3 inches) fell at San Rafael. More remarkable is the fact that, usually, only 18 mm (0.7 inches) of rain falls in the whole of April. Try telling the locals there that it will only be a passing shower!

Weather News from the last five days:
05/04/2004
04/04/2004
03/04/2004
02/04/2004
01/04/2004

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