Outlook fine for summer seasonal weather forecasts
Summer seasonal weather forecasting could become much more accurate thanks to new research by climate scientists at the National Centre for Atmospheric Science, based at the University of Reading.
The team of climate scientists has found that springtime sea temperatures in the North Atlantic can be used to predict rainfall in July and August much more accurately than current seasonal forecast methods.
The research, published in the journal Proceedings of the National Academy of Sciences, shows how the technique could lead to much more useful seasonal summer forecasts for Western Europe, including for the UK and Ireland.
Summer weather patterns in Western Europe are heavily dependent on the position and speed of the jet stream, the high-level ribbon of air that travels eastwards across the Atlantic and steers storms either towards or away from the continent.
The researchers found that sea surface temperatures in the spring play an important role in influencing a pattern of circulation that builds up in the atmosphere over the eastern Atlantic in the summer. This in turn can change both position of the jet stream, and the creation of storms.
Dr Albert Osso, Research Scientist from NCAS at the University of Reading, led the research.
He said: “The current seasonal forecast models do a fairly good job predicting weather patterns over the UK during winter, but have almost no skill in predicting summer weather in the UK and Western Europe. Our results represent a real breakthrough, since we are able to predict some important aspects of the patterns of wind and rainfall in the summer.
“We studied the relationship between the surface temperature of the North Atlantic Ocean in spring and subsequent summer weather patterns. We found that the ocean temperatures influence the development of weather systems and this influence can be exploited to make predictions. At the moment, this influence is not well simulated by existing seasonal forecast models, so our research suggests these could be improved in future.”
Professor Rowan Sutton, Director of Climate Research at NCAS, University of Reading, a co-author of the research, said: “This is an exciting finding. It shows that some aspects of summer weather in the UK appear to be much more predictable, many months ahead, than was previously thought.
“While the perfect weather forecast will never exist, our results show it should be possible to predict the likelihood of a wet or dry summer with a level of skill that could be useful for many applications.
“Farmers could potentially make more informed decisions on planting and harvesting. Shops could have more information to plan their stocks of sun cream or wellies. Forecasters still won’t be able to tell you in May if an August bank holiday barbecue is a good idea or not, but they may be able to say if the summer is likely to be wetter or drier than average, with much more accuracy.”
Osso, A., Sutton, R., Shaffrey, L., and Dong, B. Observational evidence of European summer weather patterns predictable from spring. Proceedings of the National Academy of the Sciences (2017).
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