Wednesday is going to be troublesome across the SW and Solent region I fear. Today's dosage of 12.6mm here was able to generate some slight flooding along the River Avon and more notable flooding along many of its tributaries, though not all that much really.
The point is, GFS is giving 15-25mm widely across the SW and Solent regions on Wednesday, following from 5-10mm tomorrow, and that will produce more of a response, though it will always be a slow process with the main rivers like the Stour and the Avon, of course.
The 12z GFS op run follows that up with some showers on Thursday giving 2-5mm and then something more organised on Friday giving 5-10mm... after which comes what could be a major rain event on Saturday; GFS shows an active frontal system slowing to a crawl, then stalling for a time, before crawling NE, as a marked disturbance develops along it. This delivers 25-40mm+ which is not something we want to be seeing.
The position of the frontal system could well shift away from the UK in future runs, so there's something to hope for in the near future!
It's amazing to reflect on the scale of last Monday's rainfall event across England and Wales - locally, the total was in excess of 70mm in 24 hours, which is very close to the sum of the average figures for all of the projected rainfall events discussed above!
By the way it's worth noting that in my experience GFS tends to seriously underestimate convective developments - not just showers but also squall lines. It was 25mm or so too low with the total for Monday... but to be fair NAE didn't do much better!
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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