The stratosphere temperature forecast charts are updated every 6 hours. These are generated using the high resolution GFS deterministic forecasting model.
The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. Warming in the stratosphere can indicate an increased chance of colder weather in the UK during the winter.
A sudden stratospheric warming (SSW) is an event where stratospheric temperatures rise by tens of degrees celcius causing the polar vortex of westerly winds to slow down or even reverses direction over the course of a few days. Displacement of cold arctic air to mid latitude regions follows leading to an increased chance of wintry weather in the UK.