"Will Hand" wrote in message news:...

"Will Hand" wrote in message news:...

"Jon O'Rourke" wrote in message
...
"Will Hand" wrote in message
...
GFS DT12Z 4/12/09

Shows battle lines drawn by as early as next Saturday. As suggested by
the ensembles earlier this week
a deep Atlantic low throws up a ridge over Britain on Thursday and then
this merges with the Russian high containing extremely deep cold air
and the density easterly current surges westwards as I expected
yesterday.
Britain could be in a very wintry setup as early as next weekend. As
this is backed up by previous ensemble runs and consistent dynamics I'm
getting more confident. Expect a few more flip-flops of course and the
cold may yet stay just to the east of us but we will be entering a
different weather regime after less than a week from now.



Looks that way, Will. By next Friday EC's 12Z operational run has
developed a strong upper block over western Europe. Even if there's not
cold air in depth by then the low level flow into the UK could be quite
chilly. Will be interesting to see how this fits with the midday
ensemble data.

Jon.

12Z ensembles are rocking and rolling Jon. Party on!


No real change today. As Darren says a change in the weather later next
week is practically certain. What interests me is the consistent and
strong development of a northern block, predicted by some models last
month. This is feeding sub 492 DAM air into Russia which will filter west
as a density current and could take many by surprise. Even next weekend we
are looking at below normal temperatures in the UK with night frost.
Ensembles still suggest that a cold or even very cold spell is on the
cards. Even at T+240 the Spaghetti plots are more confident than normal
showing an upper high over Britain with a very cold trough over Russia.
The ensemble mean is now beginning to show a developing low pressure
region over Poland which will strengthen more any very cold easterly. Next
week is going to be most interesting watching how this is all going to pan
out.

Will
--

DT 12Z ECM 5th is showing an omega block developing centred over Britain
extending into the Arctic next Sunday/Monday with bitterly cold air (sub 492
DAM) to the east. That model is consistent with 12Z GFS ensembles and with
itself in a time-lagged sense. Weather regime change is on the way!

Will
--

On Dec 5, 6:59*pm, "Will Hand" wrote:
"Will Hand" wrote in message news:...

"Will Hand" wrote in message news:...

"Jon O'Rourke" wrote in message
...
"Will Hand" wrote in message
...
GFS DT12Z 4/12/09

Shows battle lines drawn by as early as next Saturday. As suggested by
the ensembles earlier this week
a deep Atlantic low throws up a ridge over Britain on Thursday and then
this merges with the Russian high containing extremely deep cold air
and the density easterly current surges westwards as I expected
yesterday.
Britain could be in a very wintry setup as early as next weekend. As
this is backed up by previous ensemble runs and consistent dynamics I'm
getting more confident. Expect a few more flip-flops of course and the
cold may yet stay just to the east of us but we will be entering a
different weather regime after less than a week from now.

Looks that way, Will. By next Friday EC's 12Z operational run has
developed a strong upper block over western Europe. Even if there's not
cold air in depth by then the low level flow into the UK could be quite
chilly. Will be interesting to see how this fits with the midday
ensemble data.

Jon.

12Z ensembles are rocking and rolling Jon. Party on!

No real change today. As Darren says a change in the weather later next
week is practically certain. What interests me is the consistent and
strong development of a northern block, predicted by some models last
month. This is feeding sub 492 DAM air into Russia which will filter west
as a density current and could take many by surprise. Even next weekend we
are looking at below normal temperatures in the UK with night frost.
Ensembles still suggest that a cold or even very cold spell is on the
cards. Even at T+240 the Spaghetti plots are more confident than normal
showing an upper high over Britain with a very cold trough over Russia.
The ensemble mean is now beginning to show a developing low pressure
region over Poland which will strengthen more any very cold easterly. Next
week is going to be most interesting watching how this is all going to pan
out.

Will
--

DT 12Z ECM 5th is showing an omega block developing centred over Britain
extending into the Arctic next Sunday/Monday with bitterly cold air (sub 492
DAM) to the east. That model is consistent with 12Z GFS ensembles and with
itself in a time-lagged sense. Weather regime change is on the way!

Will
--- Hide quoted text -

- Show quoted text -

Well, I don't know Will! It's not the battleground between east and
west that was promised for a short time last weekend. That was a
classic battle between an easterly flow, around a Scandinavian high
and the Atlantic fighting from the West and it's outcome date would
have been the 11th Dec. The gfs now shows (and has I think shown for
48 hours - though sorry I haven't been able to comment through
yesterday and this morning)) the development of a high to our south at
T96, which drifts northwards over the UK and then settles just to our
SE. After it does, an omega block forms, as heights finally begin to
rise over Scandinavia. There is a possibility that this will drag in
cold air at T240+, but I'd need another 3/4 runs and agreement with
the ECM to forecast that cold air would approach the UK and not sink
towards Greece.

On the other hand, the ECM 00z showed a very odd and uncharacteristic
development at T168 with a "sausage" high over Scotland, stretching
into the Atlantic and dragging easterly air over the UK as soon as
next friday/Saturday. On the 12z ECM, a high is now shown developing
over Spain and drifting northwards to sit to our SE by T144. Pressure
is then shown to rise over Scandinavia and to join with this high and
though this could have a cold effect on the UK, it's a long way off
and not shown as fully enveloping us, even at T240.

The development is similar on both models and the possibility of this
developing fully into an omega block can't be discounted. i.e. there
are possibilities of a cold NE/E flow into the second half of
December, but I feel it is by no means as certain as you do! Again,
this has nothing to do with an original Scandinavian high and a
classic W/E UK battleground by the 11th. Yesterday morning the models
changed to show the development of high pressure over the UK at around
9 days. I was actually on the brink of a forecast of SW winds, at 10
days, last Thursday evening (i.e. next Sunday). The change shown on
Friday lowered the possibility of that forecast.

There is a chance of colder air being drawn across the UK from the
east during the 3rd week of Christmas, but you are brave man for
having forecast it Will!

"Dawlish" wrote in message
...
On Dec 5, 6:59 pm, "Will Hand" wrote:
"Will Hand" wrote in message news:...

"Will Hand" wrote in message news:...

"Jon O'Rourke" wrote in message
...
"Will Hand" wrote in message
...
GFS DT12Z 4/12/09

Shows battle lines drawn by as early as next Saturday. As suggested
by
the ensembles earlier this week
a deep Atlantic low throws up a ridge over Britain on Thursday and
then
this merges with the Russian high containing extremely deep cold air
and the density easterly current surges westwards as I expected
yesterday.
Britain could be in a very wintry setup as early as next weekend. As
this is backed up by previous ensemble runs and consistent dynamics
I'm
getting more confident. Expect a few more flip-flops of course and
the
cold may yet stay just to the east of us but we will be entering a
different weather regime after less than a week from now.

Looks that way, Will. By next Friday EC's 12Z operational run has
developed a strong upper block over western Europe. Even if there's
not
cold air in depth by then the low level flow into the UK could be
quite
chilly. Will be interesting to see how this fits with the midday
ensemble data.

Jon.

12Z ensembles are rocking and rolling Jon. Party on!

No real change today. As Darren says a change in the weather later next
week is practically certain. What interests me is the consistent and
strong development of a northern block, predicted by some models last
month. This is feeding sub 492 DAM air into Russia which will filter
west
as a density current and could take many by surprise. Even next weekend
we
are looking at below normal temperatures in the UK with night frost.
Ensembles still suggest that a cold or even very cold spell is on the
cards. Even at T+240 the Spaghetti plots are more confident than normal
showing an upper high over Britain with a very cold trough over Russia.
The ensemble mean is now beginning to show a developing low pressure
region over Poland which will strengthen more any very cold easterly.
Next
week is going to be most interesting watching how this is all going to
pan
out.

Will
--

DT 12Z ECM 5th is showing an omega block developing centred over Britain
extending into the Arctic next Sunday/Monday with bitterly cold air (sub
492
DAM) to the east. That model is consistent with 12Z GFS ensembles and with
itself in a time-lagged sense. Weather regime change is on the way!

Will
--- Hide quoted text -

- Show quoted text -

Well, I don't know Will! It's not the battleground between east and
west that was promised for a short time last weekend. That was a
classic battle between an easterly flow, around a Scandinavian high
and the Atlantic fighting from the West and it's outcome date would
have been the 11th Dec. The gfs now shows (and has I think shown for
48 hours - though sorry I haven't been able to comment through
yesterday and this morning)) the development of a high to our south at
T96, which drifts northwards over the UK and then settles just to our
SE. After it does, an omega block forms, as heights finally begin to
rise over Scandinavia. There is a possibility that this will drag in
cold air at T240+, but I'd need another 3/4 runs and agreement with
the ECM to forecast that cold air would approach the UK and not sink
towards Greece.

On the other hand, the ECM 00z showed a very odd and uncharacteristic
development at T168 with a "sausage" high over Scotland, stretching
into the Atlantic and dragging easterly air over the UK as soon as
next friday/Saturday. On the 12z ECM, a high is now shown developing
over Spain and drifting northwards to sit to our SE by T144. Pressure
is then shown to rise over Scandinavia and to join with this high and
though this could have a cold effect on the UK, it's a long way off
and not shown as fully enveloping us, even at T240.

The development is similar on both models and the possibility of this
developing fully into an omega block can't be discounted. i.e. there
are possibilities of a cold NE/E flow into the second half of
December, but I feel it is by no means as certain as you do! Again,
this has nothing to do with an original Scandinavian high and a
classic W/E UK battleground by the 11th. Yesterday morning the models
changed to show the development of high pressure over the UK at around
9 days. I was actually on the brink of a forecast of SW winds, at 10
days, last Thursday evening (i.e. next Sunday). The change shown on
Friday lowered the possibility of that forecast.

There is a chance of colder air being drawn across the UK from the
east during the 3rd week of Christmas, but you are brave man for
having forecast it Will!
-----------------------------------------------------------------------

Welcome back Paul!
I have no further comment at this stage except to say that JMA 12Z seems to
be the best middle ground chart sequence. That model also has "state of the
art" data assimilation and is often neglected but it is really extremely
good.

Will
--

"Dawlish" wrote in message
...
On Dec 5, 6:59 pm, "Will Hand" wrote:
"Will Hand" wrote in message news:...

"Will Hand" wrote in message news:...

"Jon O'Rourke" wrote in message
...
"Will Hand" wrote in message
...
GFS DT12Z 4/12/09

Shows battle lines drawn by as early as next Saturday. As suggested
by
the ensembles earlier this week
a deep Atlantic low throws up a ridge over Britain on Thursday and
then
this merges with the Russian high containing extremely deep cold air
and the density easterly current surges westwards as I expected
yesterday.
Britain could be in a very wintry setup as early as next weekend. As
this is backed up by previous ensemble runs and consistent dynamics
I'm
getting more confident. Expect a few more flip-flops of course and
the
cold may yet stay just to the east of us but we will be entering a
different weather regime after less than a week from now.

Looks that way, Will. By next Friday EC's 12Z operational run has
developed a strong upper block over western Europe. Even if there's
not
cold air in depth by then the low level flow into the UK could be
quite
chilly. Will be interesting to see how this fits with the midday
ensemble data.

Jon.

12Z ensembles are rocking and rolling Jon. Party on!

No real change today. As Darren says a change in the weather later next
week is practically certain. What interests me is the consistent and
strong development of a northern block, predicted by some models last
month. This is feeding sub 492 DAM air into Russia which will filter
west
as a density current and could take many by surprise. Even next weekend
we
are looking at below normal temperatures in the UK with night frost.
Ensembles still suggest that a cold or even very cold spell is on the
cards. Even at T+240 the Spaghetti plots are more confident than normal
showing an upper high over Britain with a very cold trough over Russia.
The ensemble mean is now beginning to show a developing low pressure
region over Poland which will strengthen more any very cold easterly.
Next
week is going to be most interesting watching how this is all going to
pan
out.

Will
--

DT 12Z ECM 5th is showing an omega block developing centred over Britain
extending into the Arctic next Sunday/Monday with bitterly cold air (sub
492
DAM) to the east. That model is consistent with 12Z GFS ensembles and with
itself in a time-lagged sense. Weather regime change is on the way!

Will
--- Hide quoted text -

- Show quoted text -

Well, I don't know Will! It's not the battleground between east and
west that was promised for a short time last weekend. That was a
classic battle between an easterly flow, around a Scandinavian high
and the Atlantic fighting from the West and it's outcome date would
have been the 11th Dec. The gfs now shows (and has I think shown for
48 hours - though sorry I haven't been able to comment through
yesterday and this morning)) the development of a high to our south at
T96, which drifts northwards over the UK and then settles just to our
SE. After it does, an omega block forms, as heights finally begin to
rise over Scandinavia. There is a possibility that this will drag in
cold air at T240+, but I'd need another 3/4 runs and agreement with
the ECM to forecast that cold air would approach the UK and not sink
towards Greece.

On the other hand, the ECM 00z showed a very odd and uncharacteristic
development at T168 with a "sausage" high over Scotland, stretching
into the Atlantic and dragging easterly air over the UK as soon as
next friday/Saturday. On the 12z ECM, a high is now shown developing
over Spain and drifting northwards to sit to our SE by T144. Pressure
is then shown to rise over Scandinavia and to join with this high and
though this could have a cold effect on the UK, it's a long way off
and not shown as fully enveloping us, even at T240.

The development is similar on both models and the possibility of this
developing fully into an omega block can't be discounted. i.e. there
are possibilities of a cold NE/E flow into the second half of
December, but I feel it is by no means as certain as you do! Again,
this has nothing to do with an original Scandinavian high and a
classic W/E UK battleground by the 11th. Yesterday morning the models
changed to show the development of high pressure over the UK at around
9 days. I was actually on the brink of a forecast of SW winds, at 10
days, last Thursday evening (i.e. next Sunday). The change shown on
Friday lowered the possibility of that forecast.

There is a chance of colder air being drawn across the UK from the
east during the 3rd week of Christmas, but you are brave man for
having forecast it Will!
------------------------------
Which is why I think forecasts for over 5 days can only vaguely say things
like "colder and more settled". The current version in the charts of cold
is via a different route to the one a few days ago. I'm sure if the second
half of December is generally cold a certain JB will stretch his "mild
December except for the Christmas period" to being spot on with the
"Christmas Period" becoming anything after December 12th ! (Hopefully you
meant the 3rd week of December above, not Christmas, Paul)
Dave
Footnote - I consider the Christmas period to be from December 24th to
December 30th at a push although I suspect retailers, the media and some
forecasters would take it as any time from November till February ;-(

In message , Dave Cornwell
writes
.....
There is a chance of colder air being drawn across the UK from the
east during the 3rd week of Christmas, but you are brave man for
having forecast it Will!
------------------------------
Which is why I think forecasts for over 5 days can only vaguely say things
like "colder and more settled". The current version in the charts of cold
is via a different route to the one a few days ago. I'm sure if the second
half of December is generally cold a certain JB will stretch his "mild
December except for the Christmas period" to being spot on with the
"Christmas Period" becoming anything after December 12th ! (Hopefully you
meant the 3rd week of December above, not Christmas, Paul)
Dave

Time to service or replace greenhouse heater, I guess. Warnings from
this NG get passed round the family. Very often turn out to be right, as
well, notably the strong winds last month - son stayed in on the
Saturday, and therefore knew roof covering had been blown off flat.
Thanks, all.



Footnote - I consider the Christmas period to be from December 24th to
December 30th at a push although I suspect retailers, the media and some
forecasters would take it as any time from November till February ;-(

http://www.guildfordvox.org.uk/lyric...rs_promise.htm deals
with that! - italicised bit is the bass line.
--
Peter Thomas

Peter Thomas wrote:

Difficult to see what's going to be the outcome, but, and this is a big
but, it may all happen a little later and be in time for Christmas.

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

Difficult to see what's going to be the outcome, but, and this is a big
but, it may all happen a little later and be in time for Christmas.

Then again Keith it may not happen at all

Graham

On Dec 5, 11:44*pm, "Graham" wrote:
Difficult to see what's going to be the outcome, but, and this is a big
but, it may all happen a little later and be in time for Christmas.

Then again Keith it may not happen at all

Graham

It's certainly keeping the weather internet on tenterhooks!

I think Darren's (Retron's) analysis on TWO has been very interesting
over the last 24 hours and I'd recommend a look if you haven't been
reading it. I've found his obeservations about the strength of the jet
and possible repercussions for this UK cold. Combine that with Will's
analysis on here, and that's about the best you'll get around the
weather sites. A lot of the rest is badly clouded by a *wish* for cold
and a thus a poor interpretation of the changing models.

ECM 00z shows the elusive easterly well before T240, but the gfs and
GEM still show the developing high over Spain extending towards a
developing high over Scandinavia and positioning the eventual
combination high over us. That doesn't mean we won't turn colder, with
clearer skies and frost for many and a respite from the rain really
does look on the cards now, by next weekend. Developments following
that do appear to hang on the strength of the push of warm air into
the Arctic on the western limb of the high. If a strong push happens,
the jet will have weakened and that may well allow the corresponding
movement of colder air, on the eastern limb of the high to extend
further west in the classic "omega block" mentioned by Will
yesterday.

If the jet doesn't weaken, the whole thing may sink south, giving a
cold spell to Greece and Turkey (have you ever read "snow" by Orhan
Pamuk? That's the kind of blizzard that cuts an area off and would
have us all tobogganing!) but allowing south-westerlies back over us -
a la edge of reality on the gfs.

Pattern change, or short-lived pattern interruption? I still favour
the second of those options, but there's no way I'd forecast it at the
moment! Not enough consistency, or agreement. The models really don't
handle possible easterlies well!

Rather exciting, isn't it, with Christmas in the offing!

On 6 Dec, 10:59, Dawlish wrote:
On Dec 5, 11:44*pm, "Graham" wrote:

Difficult to see what's going to be the outcome, but, and this is a big
but, it may all happen a little later and be in time for Christmas.

Then again Keith it may not happen at all

Graham

It's certainly keeping the weather internet on tenterhooks!

I think Darren's (Retron's) analysis on TWO has been very interesting
over the last 24 hours and I'd recommend a look if you haven't been
reading it. I've found his obeservations about the strength of the jet
and possible repercussions for this UK cold. Combine that with Will's
analysis on here, and that's about the best you'll get around the
weather sites. A lot of the rest is badly clouded by a *wish* for cold
and a thus a poor interpretation of the changing models.

ECM 00z shows the elusive easterly well before T240, but the gfs and
GEM still show the developing high over Spain extending towards a
developing high over Scandinavia and positioning the eventual
combination high over us. That doesn't mean we won't turn colder, with
clearer skies and frost for many and a respite from the rain really
does look on the cards now, by next weekend. Developments following
that do appear to hang on the strength of the push of warm air into
the Arctic on the western limb of the high. If a strong push happens,
the jet will have weakened and that may well allow the corresponding
movement of colder air, on the eastern limb of the high to extend
further west in the classic "omega block" mentioned by Will
yesterday.

If the jet doesn't weaken, the whole thing may sink south, giving a
cold spell to Greece and Turkey (have you ever read "snow" by Orhan
Pamuk? That's the kind of blizzard that cuts an area off and would
have us all tobogganing!) but allowing south-westerlies back over us -
a la edge of reality on the gfs.

Pattern change, or short-lived pattern interruption? I still favour
the second of those options, but there's no way I'd forecast it at the
moment! Not enough consistency, or agreement. The models really don't
handle possible easterlies well!

Rather exciting, isn't it, with Christmas in the offing!

Well, I've gone for the White Christmas bet! Got 9-1 for Waddington.
As far back as I can remember we often get a cold frosty/foggy period
during the first week to ten days of December then towards the Xmas
period the SW'lies return with any cold weather coming by the first
week of Jan. Looks different this year and I'm (fairly) hopeful with
this scenario and each model run looks favourable. Here's hoping!!

Pete L wrote:

Rather exciting, isn't it, with Christmas in the offing!

Well, I've gone for the White Christmas bet! Got 9-1 for Waddington.
As far back as I can remember we often get a cold frosty/foggy period
during the first week to ten days of December then towards the Xmas
period the SW'lies return with any cold weather coming by the first
week of Jan. Looks different this year and I'm (fairly) hopeful with
this scenario and each model run looks favourable. Here's hoping!!

My daffodils are about an inch through the soil this morning :-0
--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net