It may look benign but I can assure you there is a lot going on and plenty
of "potential".

OK let's start with Christmas. Almost a dead cert for a dry Christmas under
high pressure influence for southern Britain, more windy as you go north.
Pretty mild as well. Northern Britain is far less clear cut as that area is
closest to the developing SW'ly jet. Potential here for very windy and wet
conditions especially the further north you go, though probably mild. The
far north of Scotland and Orkney and Shetland may get into polar air with
increased potential for snow here.

Early next week a very tight low-level baroclinic zone develops in
mid-Atlantic with something like a 15-20 degree airmass contrast due to
persistence of deep cold air in north Atlantic and very warm air flooding
north around the Azores high. Not surprisingly associated with this is a
developing powerful SW-NE jet and global models are struggling developing
numerical instabilities as witnessed on ECM T+120 surface pressure chart
valid for Monday 12Z. (Note closed 1010 hPa low centres). At the left
entrance to this jet there is likely to be a rapid build of pressure which
will be a new high containing much colder air. However, around mid-week the
jet runs away NE leaving behing an interesting disrupting upper trough,.
which has been in evidence on three runs now. That could cause quite a few
headaches, with more extreme solutions like ECM bringing snow across
Scotland before cold air floods south, to probably the more likely outcome
of a spell of heavy rain before the colder air spreads south under the
building high, more like JMA 12Z run. After then probably high pressure with
night frost but where will it sit?

So all in all plenty of interest for the synopticians and potentially some
action too for weather buffs, I'm getting really interested in that
extremely tight baroclinic zone developing on Boxing day onwards as it is
close in distance to global model gridlength scale. Something could
potentially explode into life in there, and it won't be Father Christmas!
:-)

Ciao,

Will
--

Eskimo Will wrote:
It may look benign but I can assure you there is a lot going on and
plenty of "potential".

OK let's start with Christmas. Almost a dead cert for a dry Christmas
under high pressure influence for southern Britain, more windy as you go
north. Pretty mild as well. Northern Britain is far less clear cut as
that area is closest to the developing SW'ly jet. Potential here for
very windy and wet conditions especially the further north you go,
though probably mild. The far north of Scotland and Orkney and Shetland
may get into polar air with increased potential for snow here.

Early next week a very tight low-level baroclinic zone develops in
mid-Atlantic with something like a 15-20 degree airmass contrast due to
persistence of deep cold air in north Atlantic and very warm air
flooding north around the Azores high. Not surprisingly associated with
this is a developing powerful SW-NE jet and global models are struggling
developing numerical instabilities as witnessed on ECM T+120 surface
pressure chart valid for Monday 12Z. (Note closed 1010 hPa low centres).
At the left entrance to this jet there is likely to be a rapid build of
pressure which will be a new high containing much colder air. However,
around mid-week the jet runs away NE leaving behing an interesting
disrupting upper trough,. which has been in evidence on three runs now.
That could cause quite a few headaches, with more extreme solutions like
ECM bringing snow across Scotland before cold air floods south, to
probably the more likely outcome of a spell of heavy rain before the
colder air spreads south under the building high, more like JMA 12Z run.
After then probably high pressure with night frost but where will it sit?

So all in all plenty of interest for the synopticians and potentially
some action too for weather buffs, I'm getting really interested in that
extremely tight baroclinic zone developing on Boxing day onwards as it
is close in distance to global model gridlength scale. Something could
potentially explode into life in there, and it won't be Father
Christmas! :-)

Ciao,

Will
--


------------------------
Yes, I think next January will be far more interesting than this year.
We were very unlikely to get a repeat of last December but I've found
this December very interesting and variable. Much better than last Jan
and Feb for sure.
Dave

On 21/12/11 22:03, Dave Cornwell wrote:
Eskimo Will wrote:
It may look benign but I can assure you there is a lot going on and
plenty of "potential".

OK let's start with Christmas. Almost a dead cert for a dry Christmas
under high pressure influence for southern Britain, more windy as you
go north. Pretty mild as well. Northern Britain is far less clear cut
as that area is closest to the developing SW'ly jet. Potential here
for very windy and wet conditions especially the further north you go,
though probably mild. The far north of Scotland and Orkney and
Shetland may get into polar air with increased potential for snow here.

Early next week a very tight low-level baroclinic zone develops in
mid-Atlantic with something like a 15-20 degree airmass contrast due
to persistence of deep cold air in north Atlantic and very warm air
flooding north around the Azores high. Not surprisingly associated
with this is a developing powerful SW-NE jet and global models are
struggling developing numerical instabilities as witnessed on ECM
T+120 surface pressure chart valid for Monday 12Z. (Note closed 1010
hPa low centres). At the left entrance to this jet there is likely to
be a rapid build of pressure which will be a new high containing much
colder air. However, around mid-week the jet runs away NE leaving
behing an interesting disrupting upper trough,. which has been in
evidence on three runs now. That could cause quite a few headaches,
with more extreme solutions like ECM bringing snow across Scotland
before cold air floods south, to probably the more likely outcome of a
spell of heavy rain before the colder air spreads south under the
building high, more like JMA 12Z run. After then probably high
pressure with night frost but where will it sit?

So all in all plenty of interest for the synopticians and potentially
some action too for weather buffs, I'm getting really interested in
that extremely tight baroclinic zone developing on Boxing day onwards
as it is close in distance to global model gridlength scale. Something
could potentially explode into life in there, and it won't be Father
Christmas! :-)

Ciao,

Will
--


------------------------
Yes, I think next January will be far more interesting than this year.
We were very unlikely to get a repeat of last December but I've found
this December very interesting and variable. Much better than last Jan
and Feb for sure.
Dave

I'm hoping that Jan and Feb will have more to offer than day after day
of gloom like we had in the SE this year.

On Dec 21, 8:01*pm, "Eskimo Will" wrote:
It may look benign but I can assure you there is a lot going on and plenty
of "potential".

OK let's start with Christmas. Almost a dead cert for a dry Christmas under
high pressure influence for southern Britain, more windy as you go north.
Pretty mild as well. Northern Britain is far less clear cut as that area is
closest to the developing SW'ly jet. Potential here for very windy and wet
conditions especially the further north you go, though probably mild. The
far north of Scotland and Orkney and Shetland may get into polar air with
increased potential for snow here.

Early next week a very tight low-level baroclinic zone develops in
mid-Atlantic with something like a 15-20 degree airmass contrast due to
persistence of deep cold air in north Atlantic and very warm air flooding
north around the Azores high. Not surprisingly associated with this is a
developing powerful SW-NE jet and global models are struggling developing
numerical instabilities as witnessed on ECM T+120 surface pressure chart
valid for Monday 12Z. (Note closed 1010 hPa low centres). At the left
entrance to this jet there is likely to be a rapid build of pressure which
will be a new high containing much colder air. However, around mid-week the
jet runs away NE leaving behing an interesting disrupting upper trough,.
which has been in evidence on three runs now. That could cause quite a few
headaches, with more extreme solutions like ECM bringing snow across
Scotland before cold air floods south, to probably the more likely outcome
of a spell of heavy rain before the colder air spreads south under the
building high, more like JMA 12Z run. After then probably high pressure with
night frost but where will it sit?

So all in all plenty of interest for the synopticians and potentially some
action too for weather buffs, I'm getting really interested in that
extremely tight baroclinic zone developing on Boxing day onwards as it is
close in distance to global model gridlength scale. Something could
potentially explode into life in there, and it won't be Father Christmas!
:-)

Ciao,

Will
--

Not sure I believe the bizarre ridge in the EC t+240 !
http://expert-images.weatheronline.c...23112_2112.gif

Richard