An online portal developed by the UK Center for Ecology & Hydrology (UKCEH) will enable forecasters in West Africa to provide communities with earlier and more reliable warnings of major storms.
Storms in the Sahel region, which can reach over 100 km, have become more extreme since the 1980s due to global warming, with more intense rainfall. and infrastructure, leaving thousands without homes or livelihoods.
State-of-the-art weather forecasting models are struggling to predict where new storms will hit and their intensity, making it difficult to provide warnings to people in affected areas so they can protect their property and livestock or take shelter. way.
National forecast agencies in Africa can already predict storm behavior over the next few hours by observing current atmospheric conditions and analyzing hundreds of historic storms.
Now, thanks to a recent breakthrough by UKCEH scientists, they can make these short-term forecasts, called ‘nowcasts’, for six hours in advance and with a higher degree of accuracy. The new research has found that drier soils can increase the intensity of storms as they move, affecting where they go and how much precipitation they produce.
These new nowcasts and related satellite observations for West Africa are available through the UKCEH’s new free portal, which has been funded by the Natural Environment Research Council (NERC).
National forecasters can interpret the data and make localized forecasts, sending warnings to people in areas expected to be affected by a storm. Last year, as part of a trial of the nowcasting tool, forecasters in Senegal used it to issue a severe weather warning to the public via text message.
UKCEH’s Dr Steven Cole says: “The portal is a great example of how new scientific knowledge can be translated into usable real-time tools when working with forecasters. Importantly, this will help communities in West Africa better manage the risk of flooding from intense rainfall. .”
A recent study found that using land surface temperature data improves predictions of the path and strength of an approaching mesoscale convective system (MCS) up to 12 hours ahead. These “megastorms” can be larger than the size of England and unleash more than 100mm of rainfall in just one hour.
“We found a surprising level of storm predictability from land surface temperatures when testing our methodology on historical data, and West African forecasters find our approach very useful for their work,” says Professor Chris Taylor of the UKCEH.
“We would expect that medium-scale convective systems elsewhere in the world would also be influenced by drier soils. Therefore, our methodology could potentially be used to improve storm and flood warning systems in regions tropical regions such as Southeast Asia and Australia, as well as parts of the United States and South America.”
The new nowcasting portal allows forecasters to observe storm clouds in near real-time via satellite and compare them with historical storm behavior, as well as view data on current surface conditions earthly. The online tool then uses this data, updated every 15 minutes, to calculate the likelihood of a mesoscale convective system reaching different areas of the Sahel between now and six hours into the future.
UKCEH scientists continue to work with forecasting services in West Africa to increase warning lead time and reliability by combining more factors influencing storm behavior into their immediate modelling, in addition to temperature of the earth’s surface. These include soil moisture, atmospheric humidity, wind conditions and the amount of rain there has been in the previous days.
Working with ANACIM, Senegal’s national meteorological service, the UKCEH has also developed short-term forecasts of potential flood impacts and risks in Dakar which are available on the portal. He also hopes to work with other forecasting services to provide this service to other regions.