My hunch on Saturday about this week’s low ending up being named Christoph has turned out right. The Met Office have also ramped up and extended their amber warning for heavy rain they issued yesterday in connection with the storm by both area, extending it further southeastward towards the Wash, and by time, extending it from 42 to 54 hours in length. They are now expecting 150-200 mm of rain to fall in the amber area helped by the longer validity times – so much for my idea of orographic effects and rain shadow!
It’s a very oddly worded warning, which doesn’t actually say how much rain will fall on low ground at all. It does say that 100 mm is expected on higher ground and that 150-200 mm is expected in the most exposed areas whatever that means. If Bleaklow and Kinder Scout aren’t exposed areas then I don’t know what is. I’m not sure that there’s not that much snow left over high ground by now. The high speed rainfall sequence in their animation isn’t particularly helpful or convincing either, they should have really done an animation of six hourly accumulations, and slowed it down a lot. The only thing that’s missing now is a warning for strong winds which I’m surprised as not been mentioned. Here is the text of the warning.
Rain developing during Monday persists into Wednesday and Thursday, this rain associated with Storm Christoph. Rain will be heaviest and most persistent across western facing hills. Over 100 mm of rain is expected across the higher ground with the potential for 150-200 mm of rain in the most exposed areas. The rain will also lead to rapid melting of any remaining lying snow across the higher peaks adding to water entering the river network. Strong winds will accompany the rain at times and may add to travelling difficulties across higher and more exposed routes.UKMO
I notice that the BBC have missed the news in their 12.57 PM pre-recorded forecast, but I’m sure they’ll have caught up by 1.30 pm.