"Will Hand" wrote in message
...

"Graham" wrote in message
...
Here's one for Will!

Why are the models have so much trouble with the present set up?

We go from very cold to very mild, they are all over the place!!

Graham

I thought I'd already explained it, perhaps not very well!

Two things - (1) The behaviour of the low and associated warm advection in
western Atlantic (now at T+48) and largely resolved. If warm advection was
further east then some mobility into UK otherwise as now we get a slow
down and build of pressure.

(2) The second was the behaviour of the vortex over and around Norway.
This is starting to get resolved as well but not entirely. If it persisted
and came south then it would prevent the high building across to north of
Britain, if it weakened and/or drifted north then pressure would build
across putting us into an easterly where the low-level air would be
bitterly cold. Note that 850hPa temps. will not be a useful guide as cold
air will be below this to start with. The deeper cold air (if it gets
here) will bring widespread snow.
Indications are now that the vortex will indeed become weaker eventually
putting us into an easterly or even northeasterly after a cold-warm battle
which has started now.
The persistence of the vortex has been intensely interesting as I think it
has been forced from the stratosphere (where models have fewer levels) and
it has given Norway some awesome snowfalls as kindly shown to us by Bjorn!

Don't be a sucker - be prepared! :-)

Will

I'm well prepared - I've been one for three weeks!
Dave
--