About two to three decades ago, it was common that weather forecasts would go wrong and quite often the weathermen would not be taken seriously. So when in October 1987, a hurricane was brewing in Atlantic Ocean and a UK weather forecaster when asked if it is likely to hit UK, famously dismissed fears that a hurricane was on the way, only to be proved disastrously wrong few hours later.
Though technically speaking it was not a hurricane, the storm battered southern England and was the worst for nearly 300 years, causing 18 deaths and £2bn worth of damage.
Meteorologists would have us believe such forecasting catastrophes are now a thing of the past. Meteorologists claim that their four-day forecast is now as accurate as its one-day forecast was 30 years ago. Now predicting extreme weather events five to seven days in advance is possible. Twenty years ago we would only have been able to look one day ahead.
These improvements have only come after investing billions in better satellites, automatic weather stations and supercomputers. But with more than one third of the world's total economic output being affected by weather, such investment was essential. Meteorologists are getting better at forecasting "extreme weather events"
While, forecasts are improving day by day, climates are also showing lot of variations mainly due to phenomena like global warming, greenhouse gases etc. This has resulted in more extreme weather events, shifting rainfall patterns and abnormal seasons.
How weather plays a vital role
Weather affects almost everything we do, from the clothes we wear to how much beer we drink on hot days. Upto an extent, it even influences how much crime we commit and how responsive we are to the advertisements.
We can see the direct effect of weather on sales. There is an optimal temperature range for a retailer. If it is too low, people do not go to the store; if it is too high they go and do something else, and this changes by geography. Transportation, agriculture, hazard mitigation - pretty much everything including the economy is affected by weather.
Weather-related insurance claims now top $200bn (£120bn) a year
Where to site wind and solar farms, where to pump your gas supplies, the best time to promote a soft drink, where and when to transport goods by sea and air - all these decisions are dependent on reliable, accurate weather forecasts as well as an understanding of historic weather patterns. And with weather-related global insurance payouts now topping $200bn (£120bn) a year, according to the World Bank, forewarning is of increasing commercial importance.
Weather Satellites: Eyes in the space
The improvement in short-range forecasting is due to a huge increase in the number of global observations, better numerical models, and the rise of supercomputers.
Scores of geo-stationary and polar orbiting satellites bristling with a variety of sensors - along with hundreds of land, sea and air weather stations - contribute about two billion observations a day to the National Weather Service and other weather authorities around the world. The instruments are much better quality now and we have many more of them.
Increased Data Network & Better Processing
This increased accuracy is also helped by the millions of additional weather observations made by enthusiastic amateurs. Since June 2011, it has received about 150 million entries from members of the public, with contributions coming from over 180 countries across the globe.
All this data has to be collated, sorted and formatted for processing by increasingly powerful "petaflop" supercomputers, capable of carrying out one thousand million million calculations a second.
The data is fed into Numerical Weather Prediction (NWP) which are complex mathematical models that are constantly being tweaked and refined. The more accurate the snapshot of what the weather is doing now, the less guesswork there needs to be in the predictive models. This helps to make the forecasts more accurate.
Weather forecasts are also becoming more precise over smaller areas, as modern instruments record greater levels of detail. For example, meteorologists used to divide the globe up into a grid of boxes about 25x25km in size. Now they are down to 17km and there are high-resolution models that can focus on blocks of 1km.
Weather radars can now distinguish between rain, snow, sleet and hail and create 3D maps of storms with a resolution of 1km. And warnings of flash floods and tornadoes can now be targeted at specific sites with at-risk residents receiving alerts on their GPS-enabled smartphones. People's lives and their property are at risk if they do not get these forecasts in time.
Meteorology: Not an exact science
To some sceptics extending the accuracy of forecasts by several days may not seem like a dramatic improvement, but weather is wild, immensely complex and constantly in flux. It is well known that it can be raining in one town and dry and sunny in another, just a few miles away. That sort of variability is going on all over the world and throughout every layer of the atmosphere. So a 100% accurate forecast is impossible.
Then again, if you say the weather tomorrow will the same as today, 60% of the time you will be right. That is the skill level forecasters have to beat. And forecasters admit that they can never give you a perfect forecast and they never will be able to, but they can give you one with increasing reliability and accuracy. Forewarned is forearmed, they say.
And better forecasts save money - and lives.!!