St Helena – forecasting at one of the world’s most remote airports

St Helena is a long way from where you are – it’s a long way from anywhere. The nearest land (and diversion airfield) is Ascension Island 703 miles away and the mainland of Africa is at least 1200 miles away. Prior to the building of the airfield, it was also a long time from anywhere; a 2-3 day trip from Ascension Island or 5 days from Cape Town, both by ship, were the only ways most could travel to or from the Island. Continue reading

High-resolution weather modelling above San Francisco

Low cloud forecasting challenge

San Francisco International Airport (SFO) has two closely spaced parallel runways. Both runways can only be used at the same time when the approach is completely clear of any cloud. Maximum flow rates change from 35 aircraft landing per hour when there is cloud, to up to 54 per hour once the clear conditions are reached. Therefore an accurate forecast of cloud clearance can be of considerable benefit for planning for both Air Traffic Control and the airlines coming into SFO. Continue reading

What happens in a thunderstorm?

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What is a thunderstorm?

Generally thunderstorms require three conditions to form: moisture, instability and lift. They are produced by cumulonimbus clouds which are created when warm, humid air is lifted. As the air is lifted it cools and the moisture in the air condenses to form a cloud. If the air continues to rise the cloud will grow taller and water droplets in the cloud grow in size. Continue reading