comp.john wrote:
On 2009-12-07, John Hall wrote:
The GFS Ensemble 850mb temps for London are now looking decidedly
chilly:

http://91.121.93.17/pics/MT8_London_ens.png

What do the coloured P numbers mean down the left side of the chart?

I think they are the 20 ensembly members, basically 20 different runs.
If they all follow the same line then confidence is higher. e.g.:
http://www.wetterzentrale.de/pics/senspanel2401.html
This shows 20 versions of the same day....
All others can be found he
http://www.wetterzentrale.de/topkarten/fsenseur.html

--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net