Re: Forecast for winter 2011-12 in all seriousness

"Len Wood" <wavetrain@xxxxxxxxxx> wrote in message news:f682175d-c27b-442f-aac7-236a4e0f5901@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Winter (Dec, Jan, Feb) is likely to be mild.
Significantly mild statistically. That is, one standard deviation
above the 30-year average CET 1981-2010.
Reasons:
Longer wavelengths in the circumpolar vortex have become the norm
since September..
A 4-wave zonal pattern dominated in September. Phase speed of Rossby
waves increases with wavelength, meaning the 4-wave pattern is less
likely to be stationary compared with a
5-wave pattern.
This is reflected in NAOI which has switched to positive.
This year there is not a well-marked circumpolar axis as there was in
2010.

Negative SST anomaly in mid N. Atlantic but warm anomaly in SW
Approaches.

Lower than normal Arctic sea ice extent, comparable to 2007 which had
a mild winter to follow.

La Nina conditions likely to continue through winter after
strengthening in Sep 2011.

Forecasting the precipitation amounts is far more difficult. But
statistically a mild winter is usually a wet one. I have lower
confidence on that though.
Snow is likely to be a rather rare event. Even at 1017 ft. asl :-0

I would just like to say that these are not my feelings or indeed my
hunches on the subject.
;-)


Sounds pretty good reasoning to me Len!

However, I have heard rumours from a big modern building in Exeter that a sudden stratospheric major warming is a possibility this year, might throw a spanner in the works.

As for "frozen planet", great programme, but I really couldn't understand the need to wear such thick coats, surely as it was Spring it was "thin fleece" weather? :-)

Will
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