On Jul 23, 2:50�pm, Mike Tullett
wrote:
On Mon, 23 Jul 2007 13:28:22 +0100, Graham P Davis wrote in






That would only be possible if their previous view that gw would make the
jet stream move further north is incorrect, given that the present weather
is supposed to be a consequence of said jet stream being too far south.

Coincidentally, I posted on the matter of the jet stream position
yesterday.

If their previous view was incorrect, then their present (conflicting)
view may also be incorrect.
On the other hand, they may just want to keep the cake which they are
eating.

They were referring to the *average* position of the jet-stream. Forecasts
of heavier rain events caused by AGW had nothing to do with jet-stream
positions. Warmer air can carry more water. Warmer seas evaporate more
water into the atmosphere. That extra water gets dumped somewhere.

We've had summers in the past with jet-streams further south than usual but
without the amount of rain we've seen this summer.

I'd agree with all you wrote above, bar the very last half sentence. *The
amount of rain that fell recently *may* be unprecedented in recent times,
but the very fact that flood plains exist, together with their associated
fluvial deposits, indicates regular flooding over 100s/1000s of years.
Whether it was winter or summer floods though, I have no idea.

Not so. A flood plain is a valley bottom with an "old" river running
through it.

The reason it floods is because therer is a river running through it
and that it is a plain.

So called Old rivers are merely named after their situation. The fall
is not great, though it doesn't mean that the water in the centre of
the stream isn't fast flowing.

It flows fast enough that it can undercut banks when it reaches a
curve.