I reckon the atmosphere will make up its mind next week for the first half of
December.
Will it be raging zonality and mild or more blocked and colder?
Looking at all the runs DT00Z it seems to hang on a development of a small and
intense low in mid-Atlantic at T+108 and how that subsequently behaves. GEM is
one extreme developing a deep tight circulation which in the next 3 days
meanders across UK reinforcing the high to the north which then puts us is in
some sort of easterly. EC and UKMO don't develop much of a tight circulation and
move the low north. This leaves the door open for a strong jet to propagate east
out of Canada introducing the zonal setup for early Dec. Interestingly EC has a
cold zonal flow at first with possible widespread frontal snow in northern
Britain, but it soon turns much milder. UKMO zonal is less strong but still
extends across UK. GFS is on its own and a halfway house between GEM and EC with
a subsequent attempt at a northern block (consistent with some of its earlier
runs). So there we are. On that analysis alone the odds are as follows for early
Dec.

1. Zonal and mild (poss cold zonal at first) 50%
2. Cold and blocked very cold easterly 20%
3. Uncertain, possibly no-mans land, neither fully blocked nor fully zonal 30%

Of course non of the above takes into account solar factors :-)

Will
--

" I shall not commit the fashionable stupidity of regarding everything
I cannot explain as fraud. Carl Jung "

-------------------------------------------------------------------------------
A COL BH site in East Dartmoor at Haytor, Devon 310m asl (1017 feet).

mailto:
www: http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm

DISCLAIMER - All views and opinions expressed by myself are personal
and do not necessarily represent those of my employer.
-------------------------------------------------------------------------------

Cheers Will, interesting and informative

I will go for a cold zonal please.

Paul C
Brampton, Cumbria
www.bramptonweather.co.uk

On 23 Nov, 09:17, "Will Hand" wrote:

Looking at all the runs DT00Z it seems to hang on a development of a small and
intense low in mid-Atlantic at T+108 and how that subsequently behaves. GEM is
one extreme developing a deep tight circulation which in the next 3 days
meanders across UK reinforcing the high to the north which then puts us is in
some sort of easterly.

Is the GEM the Canadian model? My mind needs refreshing.

Cheers
Richard

On Fri, 23 Nov 2007 01:31:09 -0800 (PST), Richard Dixon wrote in


Looking at all the runs DT00Z it seems to hang on a development of a small and
intense low in mid-Atlantic at T+108 and how that subsequently behaves. GEM is
one extreme developing a deep tight circulation which in the next 3 days
meanders across UK reinforcing the high to the north which then puts us is in
some sort of easterly.

Is the GEM the Canadian model? My mind needs refreshing.

In a single word - "yes" - it is the Canadian model.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 23/11/2007 09:37:39 GMT

On 23 Nov, 09:17, "Will Hand" wrote:

1. Zonal and mild (poss cold zonal at first) 50%
2. Cold and blocked very cold easterly 20%
3. Uncertain, possibly no-mans land, neither fully blocked nor fully zonal 30%

I've often wondered when models diverge and are particularly chaotic,
which of the models do the best? It's all very well comparing the
models for, for example, 500hPa height error over the course of the
year or other such situations, but it would be interesting to see
which of the models cope the best when the inter-model variability is
huge and things are on a knife-edge. Maybe some work has been done on
this already?

Richard

On 23 Nov, 09:37, Mike Tullett
wrote:

Is the GEM the Canadian model? My mind needs refreshing.

In a single word - "yes" - it is the Canadian model.

Thanks Mike

In article ,
Will Hand writes:
1. Zonal and mild (poss cold zonal at first) 50%
2. Cold and blocked very cold easterly 20%
3. Uncertain, possibly no-mans land, neither fully blocked nor fully zonal 30%

Thanks, Will. Does this take the ensembles into account, or is it based
solely on the "operational" runs?
--
John Hall
"Honest criticism is hard to take,
particularly from a relative, a friend,
an acquaintance, or a stranger." Franklin P Jones

On 23 Nov, 09:58, Richard Dixon wrote:
On 23 Nov, 09:17, "Will Hand" wrote:

1. Zonal and mild (poss cold zonal at first) 50%
2. Cold and blocked very cold easterly 20%
3. Uncertain, possibly no-mans land, neither fully blocked nor fully zonal 30%

I've often wondered when models diverge and are particularly chaotic,
which of the models do the best? It's all very well comparing the
models for, for example, 500hPa height error over the course of the
year or other such situations, but it would be interesting to see
which of the models cope the best when the inter-model variability is
huge and things are on a knife-edge. Maybe some work has been done on
this already?

Richard

In my experience, the model that predicts a change of type more
consistently is GFS. However, you do have to look at each successive
run, and not just take one in isolation. All I can see in the coming
week is a slow migration of the jet stream further south. A typical
early winter scenario, with deep areas of low pressure moving east and
cold air being driven further south, and for longer periods.

"John Hall" wrote in message
...
In article ,
Will Hand writes:
1. Zonal and mild (poss cold zonal at first) 50%
2. Cold and blocked very cold easterly 20%
3. Uncertain, possibly no-mans land, neither fully blocked nor fully zonal
30%

Thanks, Will. Does this take the ensembles into account, or is it based
solely on the "operational" runs?
--

I only have access to GFS ensembles and the postage stamps are all over the
place after T+168 so not very helpful. So yes, the "hauptlauf".

Will
--

1. Zonal and mild (poss cold zonal at first) 50%
2. Cold and blocked very cold easterly 20%
3. Uncertain, possibly no-mans land, neither fully blocked nor fully zonal 30%

Of course non of the above takes into account solar factors :-)

Safest bet would be number 1!

It's been that way for much of the last 10 winters why should this one
be any different?

Still we've already had a few cms of the white stuff so musn't grumble
--
Graham