The latest ARPEGE totals for the weekend. Nearly the whole of SW England sees at least 30 mm with 40 mm or so in a numbe rof places.
The pivot point for tomorrow's rain has adjusted west since yesterday's runs, hence the generally higher totals for Cornwall and Wales, with Saturday alone producing 50 mm or so over the areas of higher terrain, with an unusually strong effect over Dartmoor that locals should bear in mind - the run-off down narrow gorges and the like could be exceptional.
In fact there must be the chance of convection lining up on a collision course with some of the high terrain to produce a flash flood somewhere. A nasty proposition indeed and I sincerely hope that is avoided.
The GFS high-res paints a very similar picture, indeed the agreement is so strong that if events turn out to be more than a hundred miles or so east or west of their projections, it will be a bit of a let down in terms of forecasting reliability.
Looking at the latest rainfall radar, I can see that the occluding system is pretty much where the models have it for 20:00, but with the addition of a narrow squall line just behind it, and the rain rates in the western Channel considerably higher than predicted. Hopefully that won't propagate along the frontal system to bring heavier rain than expected across CS England tonight - I don't think the local waterways could handle much more than 30 mm this weekend.
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T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
Keep Calm and Forecast On