OK here we go. I shall use the MetO DT 12Z 3/2/09 FAX charts as a guide as
they will be the best forecast charts available. You can see these at
http://www.wetterzentrale.de/topkarten/fsfaxsem.html

On Thursday into Friday a deep depression will move NE from Biscay at 0000
Thursday to the north French coast on the meridian by 12Z Friday. On the
T+60 chart valid for 0000 GMT Friday there are three fronts in evidence.
Going north - south we have the cold front delineating deep cold arctic air
set to come across Britain next weekend. Then we have an occlusion
straddling the centre, to the south of this is milder air but not warm air.
To the north will be the air we have at present in the SW (i.e.cold). The
southern occlusion marks the change to true mild air, which will never get
into UK. To the south and east of the middle occlusion at T+60 we should
have mostly rain. To the north and east as far as the cold front we will
have a wintry mix of rain, sleet and snow, with snow above circa 250m asl.
On the cold front it will be mostly snow at all levels. On Friday notice
that all the fronts move southeastwards, turning rain increasingly to snow
lower down. But ... pressure will be rising quickly to the north of the cold
front in the left entrance to the slightly confluent upper trough and it is
here where temporary blizzard-like conditions could occur. The other thing
to watch is that if there is any deepening and slowing of the low then the
severity of the event will increase. So basically a "rain turning to snow
event" with higher ground catching most snow. These situations have
potential to give copious precipitation amounts to the north and west of the
low centre, hence the warnings of that *potential* . Northern England
northwards should escape the "worst".

I hope that is helpful.

Now I've missed the start of Eastenders :-)

Ciao,

Will
--

Now I've missed the start of Eastenders :-)

Ciao,

Will
--

Good!

On Feb 3, 7:36*pm, "Will Hand" wrote:
OK here we go. I shall use the MetO DT 12Z 3/2/09 FAX charts as a guide as
they will be the best forecast charts available. You can see these athttp://www.wetterzentrale.de/topkarten/fsfaxsem.html

On Thursday into Friday a deep depression will move NE from Biscay at 0000
Thursday to the north French coast on the meridian by 12Z Friday. On the
T+60 chart valid for 0000 GMT Friday *there are three fronts in evidence.
Going north - south we have the cold front delineating deep cold arctic air
set to come across Britain next weekend. Then we have an occlusion
straddling the centre, to the south of this is milder air but not warm air.

wrote:
On Feb 3, 7:36 pm, "Will Hand" wrote:
OK here we go. I shall use the MetO DT 12Z 3/2/09 FAX charts as a
guide as
they will be the best forecast charts available. You can see these
athttp://www.wetterzentrale.de/topkarten/fsfaxsem.html

On Thursday into Friday a deep depression will move NE from Biscay
at 0000
Thursday to the north French coast on the meridian by 12Z Friday. On
the
T+60 chart valid for 0000 GMT Friday there are three fronts in
evidence.
Going north - south we have the cold front delineating deep cold
arctic air
set to come across Britain next weekend. Then we have an occlusion
straddling the centre, to the south of this is milder air but not
warm air.
To the north will be the air we have at present in the SW
(i.e.cold). The
southern occlusion marks the change to true mild air, which will
never get
into UK. To the south and east of the middle occlusion at T+60 we
should
have mostly rain. To the north and east as far as the cold front we
will
have a wintry mix of rain, sleet and snow, with snow above circa
250m asl.
On the cold front it will be mostly snow at all levels. On Friday
notice
that all the fronts move southeastwards, turning rain increasingly
to snow
lower down. But ... pressure will be rising quickly to the north of
the cold
front in the left entrance to the slightly confluent upper trough
and it is
here where temporary blizzard-like conditions could occur. The other
thing
to watch is that if there is any deepening and slowing of the low
then the
severity of the event will increase. So basically a "rain turning to
snow
event" with higher ground catching most snow. These situations have
potential to give copious precipitation amounts to the north and
west of the
low centre, hence the warnings of that *potential* . Northern England
northwards should escape the "worst".

I hope that is helpful.

Now I've missed the start of Eastenders :-)

Ciao,

Will
--

So it looks like the SE is going to be in the grotty sector :-(
So maybe not good for *more* snow, but do you see the areas which got
heavy snow yesterday (i.e. London, Surrey, etc) surviving this event
or will it all be gone by the weekend?

Nick

The SE is going to be in the "rain-turning-to-snow" bit.
I don't think the snow now in the SE will be quite as good, there will be
compaction and more thawing tomorrow, especially on low ground facing south.
But I'm sure on the north facing slopes of the Downs etc. there will still
be some snow left. 30cm of snow takes some shifting after a few freeze-thaw
cycles! Unless it rains really hard, but if it does rain hard it will turn
to snow quicker anyway.

I don't have a crystal ball, sorry.

Will
--

I hope that is helpful.

Now I've missed the start of Eastenders :-)

Ciao,

Will
--





Yes indeed - with the help of the fax charts I can see your explanation
show south and mid Wales in the firing line for the event.

So glad you were distracted ;-))

James
--
James Brown

On Feb 3, 7:36*pm, "Will Hand" wrote:
OK here we go. I shall use the MetO DT 12Z 3/2/09 FAX charts as a guide as
they will be the best forecast charts available. You can see these athttp://www.wetterzentrale.de/topkarten/fsfaxsem.html

On Thursday into Friday a deep depression will move NE from Biscay at 0000
Thursday to the north French coast on the meridian by 12Z Friday. On the
T+60 chart valid for 0000 GMT Friday *there are three fronts in evidence.
Going north - south we have the cold front delineating deep cold arctic air
set to come across Britain next weekend. Then we have an occlusion
straddling the centre, to the south of this is milder air but not warm air.

Dick wrote:
On Feb 3, 7:36 pm, "Will Hand" wrote:
OK here we go. I shall use the MetO DT 12Z 3/2/09 FAX charts as a
guide as
they will be the best forecast charts available. You can see these
athttp://www.wetterzentrale.de/topkarten/fsfaxsem.html

On Thursday into Friday a deep depression will move NE from Biscay
at 0000
Thursday to the north French coast on the meridian by 12Z Friday. On
the
T+60 chart valid for 0000 GMT Friday there are three fronts in
evidence.
Going north - south we have the cold front delineating deep cold
arctic air
set to come across Britain next weekend. Then we have an occlusion
straddling the centre, to the south of this is milder air but not
warm air.
To the north will be the air we have at present in the SW
(i.e.cold). The
southern occlusion marks the change to true mild air, which will
never get
into UK. To the south and east of the middle occlusion at T+60 we
should
have mostly rain. To the north and east as far as the cold front we
will
have a wintry mix of rain, sleet and snow, with snow above circa
250m asl.
On the cold front it will be mostly snow at all levels. On Friday
notice
that all the fronts move southeastwards, turning rain increasingly
to snow
lower down. But ... pressure will be rising quickly to the north of
the cold
front in the left entrance to the slightly confluent upper trough
and it is
here where temporary blizzard-like conditions could occur. The other
thing
to watch is that if there is any deepening and slowing of the low
then the
severity of the event will increase. So basically a "rain turning to
snow
event" with higher ground catching most snow. These situations have
potential to give copious precipitation amounts to the north and
west of the
low centre, hence the warnings of that *potential* . Northern England
northwards should escape the "worst".

I hope that is helpful.

Now I've missed the start of Eastenders :-)

Ciao,

Will
--

Will

I dont think the T+60 chart is based on the latest 12Z model run, but
on the old 00Z output. I say that because the 850mb WBPT pattern from
the 12Z run at T+60 would place the southern occlusion over southeast
England in the axis of a PS06 C isopleth.
http://meteocentre.com/models/ukmet_..._060_0850.html

The associated surface low looks as though it is probably centered
over Hampshire. All of this on the face of it would suggest that the
area most likely to have snow is probably going to be a little further
north. However, undercutting of cold air beneath the 850mb level and
the intensity of precipitation will complicate the issue of course.

Dick Lovett
Charlbury

You're assuming that the 12Z should have been believed. That is why I chose
to use the FAX issue as the best stab! I agree it's all very difficult
though, hence the uncertainty.

Will
--

"Will Hand" wrote in
:

So basically a "rain turning
to snow event" with higher ground catching most snow. These situations
have potential to give copious precipitation amounts to the north and
west of the low centre, hence the warnings of that *potential* .
Northern England northwards should escape the "worst".

Am sure some areas will see their heaviest snow of the winter in the next
few days. For those of us treated in the last 48 hours, I can't help
thinking it'll be a touch of after the Lord Mayor's Show!

The one thing I like about these situations that have so many potential
snow events over a few days is often one of the more inocuous possible
events ends up stealing the show.

Now I've missed the start of Eastenders :-)

Hopefully you'll miss the rest of it too! If I want to watch 30 minutes of
arguing I'll find a pub at kicking-out time

Richard

Richard Dixon wrote:
"Will Hand" wrote in
:

So basically a "rain turning
to snow event" with higher ground catching most snow. These
situations have potential to give copious precipitation amounts to
the north and west of the low centre, hence the warnings of that
*potential* . Northern England northwards should escape the "worst".

Am sure some areas will see their heaviest snow of the winter in the
next few days. For those of us treated in the last 48 hours, I can't
help thinking it'll be a touch of after the Lord Mayor's Show!

The one thing I like about these situations that have so many
potential snow events over a few days is often one of the more
inocuous possible events ends up stealing the show.


How very true!

Now I've missed the start of Eastenders :-)

Hopefully you'll miss the rest of it too! If I want to watch 30
minutes of arguing I'll find a pub at kicking-out time

Richard

The Queen Vic perhaps :-)

Will
--

On Feb 3, 9:37*pm, "Will Hand" wrote:
Dick wrote:
On Feb 3, 7:36 pm, "Will Hand" wrote:
OK here we go. I shall use the MetO DT 12Z 3/2/09 FAX charts as a
guide as
they will be the best forecast charts available. You can see these
athttp://www.wetterzentrale.de/topkarten/fsfaxsem.html

On Thursday into Friday a deep depression will move NE from Biscay
at 0000
Thursday to the north French coast on the meridian by 12Z Friday. On
the
T+60 chart valid for 0000 GMT Friday there are three fronts in
evidence.
Going north - south we have the cold front delineating deep cold
arctic air
set to come across Britain next weekend. Then we have an occlusion
straddling the centre, to the south of this is milder air but not
warm air.
To the north will be the air we have at present in the SW
(i.e.cold). The
southern occlusion marks the change to true mild air, which will
never get
into UK. To the south and east of the middle occlusion at T+60 we
should
have mostly rain. To the north and east as far as the cold front we
will
have a wintry mix of rain, sleet and snow, with snow above circa
250m asl.
On the cold front it will be mostly snow at all levels. On Friday
notice
that all the fronts move southeastwards, turning rain increasingly
to snow
lower down. But ... pressure will be rising quickly to the north of
the cold
front in the left entrance to the slightly confluent upper trough
and it is
here where temporary blizzard-like conditions could occur. The other
thing
to watch is that if there is any deepening and slowing of the low
then the
severity of the event will increase. So basically a "rain turning to
snow
event" with higher ground catching most snow. These situations have
potential to give copious precipitation amounts to the north and
west of the
low centre, hence the warnings of that *potential* . Northern England
northwards should escape the "worst".

I hope that is helpful.

Now I've missed the start of Eastenders :-)

Ciao,

Will
--

Will

I dont think the T+60 chart is based on the latest 12Z model run, but
on the old 00Z output. I say that because the 850mb WBPT pattern from
the 12Z run at T+60 would place the southern occlusion over southeast
England in the axis of a PS06 C isopleth.
http://meteocentre.com/models/ukmet_..._060_0850.html

The associated surface low looks as though it is probably centered
over Hampshire. All of this on the face of it would suggest that the
area most likely to have snow is probably going to be a little further
north. However, undercutting of cold air beneath the 850mb level and
the intensity of precipitation will complicate the issue of course.

Dick Lovett
Charlbury

You're assuming that the 12Z should have been believed. That is why I chose
to use the FAX issue as the best stab! I agree it's all very difficult
though, hence the uncertainty.

Will
--- Hide quoted text -

- Show quoted text -

No, it wasn't a case of believing any particular model run. I was only
pointing out that the T+60 fax chart does not appear to be based on
the latest 12Z output.

Dick