A very active area of low pressure is expected to impact the British Isles tomorrow. Rainfall rates over 10mm per hour for several hours are expected across western parts of England and Wales. It’s across South Wales and SW England where near 75mm (3″) of rainfall is likely. Locally up to 100mm (4″) may fall. A very persistent weather front will be responsible for these very high amounts.
As per above, the UK Met Office have issued rainfall warnings for much of South Western Britain. Of much interest is the Amber warning, meaning you should be prepared, for South Wales. Seriously high river levels are likely to develop here during the afternoon tomorrow. Be on alert, especially if you live in a flood prone area in the South Wales valleys. Those in the yellow warning should also keep an eye.