The Met Office is entering an exciting new chapter with the arrival of a scientific model upgrade – our first major science upgrade to operational weather modelling in over three years and the first on our new supercomputer.
This upgrade represents a significant leap in our ability to understand rapidly evolving weather patterns and provide the most reliable forecasts for the UK and beyond.
The recent scientific model upgrade brings together advances in atmospheric science, new forms of observational data, and improvements in the way we represent physical processes within the atmosphere. The result is a suite of changes that will ultimately support better decision-making for the public, businesses, emergency responders and global partners.
In this article, we explore what the upgrade delivers, why it matters and how these improvements will enhance weather resilience across multiple sectors.
Stronger foundations through improved model performance
At the heart of the new model upgrade is a measurable improvement in both global and UK model forecast performance scores. These upgrades are driven by three core developments: improved model physics, the assimilation of additional aircraft observations and the recalibration of our ensemble prediction system. Together, these changes make the models more representative of real-world conditions and more responsive to rapidly changing weather.
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The inclusion of additional aircraft observations represents a major step forward, providing more detailed information on wind and temperature at various atmospheric levels and enhancing the accuracy of forecasts from the earliest stages of model initialisation. Alongside this, an update to the representation of uncertainty in our ensemble system enables more robust and useful predictions.
Delivering more realistic rainfall forecasts
One of the most significant scientific advances within the model upgrade is the introduction of the Cloud and AeroSol Interacting Microphysics (CASIM), a world-leading cloud microphysics scheme. Microphysics governs how cloud droplets, ice particles, rain and snow form and interact – essential ingredients for getting rainfall right.
With CASIM now implemented into the UK model, our precipitation forecasts look more realistic than ever. The new system sharpens the representation of both light and heavy rainfall, providing clearer and more accurate maps for forecasters and the public.
This improvement is particularly important for hydrology, flood forecasting, outdoor events and emergency response. More precise rainfall information helps to guide water management decisions, plan safer operations and provide earlier and more targeted weather warnings.
Greater accuracy in cloud cover and cloud base forecasts
Cloud forecasting plays a vital role in aviation, transport, renewable energy and day-to-day public planning. The new scientific model upgrade also brings notable improvements to how cloud cover and cloud base height are represented across the UK.
These gains stem from major changes to the cloud scheme within the model, paired with the reintroduction of quality-controlled visibility observations into data assimilation. The result is a more accurate depiction of low cloud, fog and mist – conditions that have major operational implications for airports and airlines.
Better forecasting of cloud base supports safer and more efficient air travel. It helps aviation teams manage take-offs and landings, reduce delays and maintain fuel efficiency. For the wider public, improved visibility and cloud cover forecasts will enhance safety on the roads and support more confident decision-making for travel and outdoor activities.
Improving winter resilience through better temperature forecasts
Temperature forecasts are central to winter planning across the UK. The new scientific model upgrade introduces refinements that enhance the accuracy of UK winter temperature predictions, which has direct benefits for sectors that rely on advance knowledge of cold weather.
Energy providers, for example, can use more precise data to anticipate demand more effectively, helping to stabilise supply and reduce costs. Local authorities responsible for gritting and de-icing operations will be able to plan treatments more efficiently and improve safety on the road network. These enhancements support national resilience, protect the public and enable more sustainable use of resources.
Extending the global ensemble forecast range
Another milestone is the extension of the global ensemble forecast range from 7 to 10 days. Ensemble forecasting is a crucial tool for understanding uncertainty and identifying potential severe weather events further in advance.
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By providing more information to meteorologists to look three days deeper into the future, the upgrade potentially enables earlier identification of impactful weather systems that may affect the UK. This enhanced range supports earlier issuance of weather warnings when confidence allows, helping communities prepare ahead of severe conditions.
The benefits extend beyond the UK. The Armed Forces, for example, rely on accurate medium-range ensemble guidance to plan field operations, coordinate logistics and protect personnel in challenging environments.
Better global storm predictions to protect communities worldwide
Improvements to the representation of convection in the global model are leading to more accurate predictions of tropical cyclones. This includes better estimates of storm strength, track and development – critical information for safeguarding lives and property.
These advancements support international partners, humanitarian organisations and UK nationals living overseas. By improving the accuracy of intensity predictions, communities can better prepare for extreme weather, reducing the risk of harm and minimising disruption.
Moving forward
The scientific model upgrades mark a major step in the evolution of Met Office forecasting capability and is the first major scientific advancement delivered using the Met Office’s new supercomputer. Through enhanced physics, new data sources and extended prediction ranges, this upgrade strengthens our ability to provide accurate, timely and actionable weather information.
As the impacts of weather become increasingly complex and far-reaching, our forecasting systems remain world-leading, supporting a safer, more resilient future for the UK and global communities alike.
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