"Freddie" wrote in message
.net...
On Wed, 26 Dec 2012 10:39:35 -0000, "Alastair McDonald"
wrote:
But if it is going to bring us cold weather surely the stratwarm
has to
happen at the right longitude.

It's a bit more complex than that. A disruption to the zonal flow anywhere
in our hemisphere will have a downstream effect right round the globe -
dependent on the strength and the orientation of the disruption. I doubt
there is a 'right' longitude.

Yes, but the net the zonal flow must always be zero otherwise all the air
would gather at one longitude. So what happens is that the flow is a closed
loop, but becomes more wavy as the stratwarm forms. To a first
approximation, we will get cold weather if a wave/loop comes south over us,
so the stratwarm has to form at 180 degrees west to produce the warm
northern loop. In fact for us to get snow we need the southern loop of polar
air to form over Russia and expand westward. I don't think a stratwarm
centred on Moscow would bring us snow.

Cheers, Alastair.