Mossdale.

[paul]

Ironically, today the BBC Weather forecast here in the UK shows Hurricane Force Winds! (yes - it;s a bug...) https://www.bbc.co.uk/news/articles/c0kjrp2rngzo

 

[JAA]

I’ve often thought a frosty spring morning without any snow cover on the ground would be a pretty safe time for flood prone systems?

 

[Tim Pickering]

From a position of relative inexperience and ignorance - is there an answer to this? Now or in the future?

What specific weather carries the risk?

When in the year/season is the worst risk?

Was Mossdale compounded by either or was it just bad luck?

A tragedy of this scale hasn’t been repeated, but do we actually know any better now? We surely have more weather data but are we better equipped with knowledge as an average caver to make the right call on the day?

Hot and humid weather lends itself well to this kind of phenomenon. We are prone to rainfall in the Dales because of the hilly/mountainy topography and proximity to the coast. You get your warm, moist air coming in from the Atlantic, which is then driven over the hills where it cools and condenses into clouds. As it sinks you get a lot of convection as the cooler air displaces warmer air. In the case of a cloudburst, you get rising warm air trapping the sinking orographic air parcel, which pretty much blocks the rainfall. Think of the trapped rainfall as a sandwich filling. You get a back log of rain, if you like. When that rising warm air weakens, you get a lot of rain dumped in a very short space of time over a very small area. Valleys lend themselves well to cloudbursts.

These rainfall events are quick to form, and extremely localised therefore very hard to predict with the current methods of gathering and analysing data. The best the Met Office can do is issue a warning of the likelihood of heavy, localised downpours but they can't really offer a reliable time or locality. They use some mathematical voodoo called paramaterisation to help with forecasting small scale localised events, but I'm way out of my comfort zone now, so I'll shut up.

From what I've read about the Mossdale tragedy, I think it was mostly bad luck. Being in the wrong place at the wrong time.

As from what we can do to reduce the likelihood of a repeat is what Andrew basically stated. Don't dismiss the weather warnings, even if it turns out to be a lovely day after all. The caves aren't going anywhere any time soon.

 

[Fulk]

I was at Mossdale – not, I hasten to add as one of the very brave rescuers who actually went underground, hoping against hope to find survivors – but as a general surface dogsbody.

My memory has it (and it is a long time ago!) that digging machines were taken up there to build a dam around the scar, that must have been getting on for 2 metres high and wide enough and sturdy enough to allow a JCB to trundle along the top of it . . . even so, at one point the water rose to such an extent that it nearly came over the dam – there were rescuers underground at the time.

So, let us not forget the great bravery shown by the selfless individuals who went into the cave.