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UPDATE: Wednesday 16 June, 19:00hrs BST:
It's rare that I'd want a forecast to be wrong, but the events unfolding in France have, tragically,Ìýmatched our worst expectations and represent the extremely dangerousÌýconditions anticipatedÌýin the entry I'd written on Tuesday afternoonÌý(below).

With torrential rain and resultant flash flooding proving a major hazard, at least 19 people have been confirmed as losing their livesÌýin the appauling weather endured across parts of southern France. It's not the end of this particular event, so further perilous conditions are expected for another 24hrs or so, including across parts of France, northern Spain, northern Italy and the Alpine region.

Our gives an update on the situation as of now, as does - graphically -Ìýthe video below.

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(Original Entry from TuesdayÌýfollows)

It's looking highly likely thatÌýa spell ofÌýexceptionallyÌýnasty weatherÌýwill affect some parts of Europe over the next 48 hoursÌý(Tuesday-Thursday).

Through parts of southern France, northern Italy and across a swathe of the Alpine region, the stage is set for a genuinely extreme event, with rainfall expected to reach some 200 to 300mm throughout the period across much of this area. It's by no means impossible that some districts could see a deluge eventuallyÌýtotalling a staggeringÌý500mm (half a metre).

Either way, those sorts of rainfall accumulations, over a fairly short period of time andÌýacross terrain with steep run-offs into river catchments,Ìýare bound to lead to some veryÌýdangerous and newsworthyÌýconditions.

So why is this happening?

As I write, there's a strongÌýupper vortex drifting down through the southern Bay of Biscay and rotating eastwards across northern Spain. In the next 24hrs, it'll swing northeast into southern France and towards the Alpine region.

Coupled to this upper air process, a plume of some very warm air, originating across North Africa, is advecting northwards. During Wednesday, it will engage with the upper vortex across the NW Mediterranean and into adjacent areas of southern France and northern Italy - a very potent cocktail, from which we'll see the generation of heavy rainfall and a threat of severe thunderstorms.

The Met Office synoptic chart (below) for midnight (GMT) Tuesday night intoÌýWednesday illustrates the complex surface dynamics at play.

Some very heavy rain is already starting to feed north off the Mediterranean andÌýaffect parts of France, includingÌýnear the likes of Nice and Monaco. You can keep an eye on this developing situation through .