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13/05/2003
As the clean-up continues after a weekend of violent tornadoes in the USA, scientists are pushing technology in a bid to improve forecasting techniques.
The areas worst affected by the recent wave of severe weather have been the South and the Midwest. Along with the tornadoes, the storms systems responsible have also brought heavy rain, lightning, hail and strong winds. The levels of destruction have been vast. Many buildings have been completely destroyed, vehicles overturned and power supplies cut. Injury totals for the past week are now into the hundreds, with some of the worst cases proving fatal.
In the light of such powerful storm forces, over which there is no control, the best line of defence is accurate forecasting. It is difficult to detect actual tornadoes, but the conditions leading to their formation are easily recognised in association with large storm systems known as 'super cells'. Super cells are much easier to detect, radar being the most favoured method.
Currently Doppler radar is the most widely used. For many years monitoring has been performed by Doppler radar at fixed locations. More recently the units been mounted to mobile platforms which enable them to be moved closer to the storm cells, providing better resolution and a deeper insight into the heart of the tornado. However, even with the best Doppler radar systems, forecasters can only give a twelve-minute warning before storms strike.
Researchers at the National Severe Storm Laboratory, based in Norman, Oklahoma, aim to increase this lead time to around twenty minutes. They are currently perfecting an alternative means of detection known as 'phased-array radar', which was originally developed for the US Navy.
Phased-array radar uses multiple electronically controlled beams over a range of frequencies, in comparison to Doppler which has much more restricted operating modes. Phased-array technology reduces the scan time (the time to form a radar image) to only one minute in comparison to five or six minutes using Doppler. The scan speed will not only increase the lead time on storms but will also allow areas of severe weather to be rescanned very quickly, hence showing developmental changes too.
It is hoped this improved technology will allow forecasters to issue storm alerts further in advance and hence buy more time for people to escape the ravages of the storms path. Phased-array currently remains at a developmental stage for tornado prediction but the hopes for the next few years are high.
Weather News from the last five days:
12/05/2003
11/05/2003
10/05/2003
09/05/2003
08/05/2003
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