Does anyone have any idea of why the jet stream is so far south at the
moment? I've just looked at the GFS forecast for this week and it has
the polar jet south of the UK later in the week, and it doesn't seem to
be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

On Jun 4, 11:53*pm, Adam Lea wrote:
Does anyone have any idea of why the jet stream is so far south at the
moment? I've just looked at the GFS forecast for this week and it has
the polar jet south of the UK later in the week, and it doesn't seem to
be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?
-----------------------------------------------------------------------------------------------------------
Forcing has to be from below or above. Or both.

A bit of strat cooling may do the trick. A blast of particles from the
sun to reduce the ozone layer.

Or from below, a bit of warming. So get out there with your BBQs. Meat
eaters only.

BBQ summers don't just happen.

Len
A very soggy Wembury.

"Adam Lea" wrote in message
...
Does anyone have any idea of why the jet stream is so far south at the
moment? I've just looked at the GFS forecast for this week and it has the
polar jet south of the UK later in the week, and it doesn't seem to be in
any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream further
north, closer to where it should be for the time of year?

FWIIW, I do not think it is a direct consequence of global warming, as I
would have expected GW to move the Jet Stream northwards.

I blame the extent of Arctic sea ice which was almost back to normal during
April:
http://nsidc.org/data/seaice_index/i...timeseries.png.

It is just a matter of waiting for the JS to flip back north and then the
Barbaque Summer can begin :-)

OTOH, flpping the Jet Stream might lead to a European Monsoon.

Cheers, Alastair.

On Tue, 5 Jun 2012 20:11:34 +0100
"Alastair McDonald" wrote:


"Adam Lea" wrote in message
...
Does anyone have any idea of why the jet stream is so far south at
the moment? I've just looked at the GFS forecast for this week and
it has the polar jet south of the UK later in the week, and it
doesn't seem to be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

FWIIW, I do not think it is a direct consequence of global warming,
as I would have expected GW to move the Jet Stream northwards.

I blame the extent of Arctic sea ice which was almost back to normal
during April:
http://nsidc.org/data/seaice_index/i...timeseries.png.

I don't see what effect such a blip could have. The extent soon
returned to being well below normal. In any case, "normal" is set
during the recent period of global warming and so is well below normal
itself. ;-)


It is just a matter of waiting for the JS to flip back north and then
the Barbaque Summer can begin :-)

OTOH, flpping the Jet Stream might lead to a European Monsoon.


We're already experiencing a European Monsoon. How much colder and
wetter do you want it to get?

I see that, over the past month, the N Atlantic SST pattern has
changed. The warm area that has been around for ages has been replaced
by a cold pool near 40N 40W. This would be associated with higher than
usual pressure near Iceland and a positioning of the jet stream south
of its usual position.

--
Graham Davis, Bracknell, Berks. E-mail: change 'boy' to 'man'
"A neighbour put his budgerigar in the mincing machine and invented
shredded tweet." - Chic Murray
openSUSE Linux: http://www.opensuse.org/en/

Adam Lea wrote in message
...
Does anyone have any idea of why the jet stream is so far south at the
moment? I've just looked at the GFS forecast for this week and it has
the polar jet south of the UK later in the week, and it doesn't seem to
be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?


Or to put it the other way, I'd like to know why "our" jetstream passes over
the UK for
( my guess as I've not found figures for it) about 80 percent of the time ,
we being a relatively small section of available latitude on the globe.

On Jun 6, 8:15*am, "N_Cook" wrote:
Adam Lea wrote in message

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

Or to put it the other way, I'd like to know why "our" jetstream passes over
the UK for
( my guess as I've not found figures for it) about 80 percent of the time ,
we being a relatively small section of available latitude on the globe.

It is analogous to the equatorial counter current in the oceans. There
are more erratic ones in the Global Conveyance of ocean currents but
they all take place at known regions.

It would appear they are associated with the propensity of the
atmosphere to produce tropical storms alongside Blocking Lows in the
North Atlantic.

On 06/06/2012 07:57, Graham P Davis wrote:
On Tue, 5 Jun 2012 20:11:34 +0100
"Alastair wrote:


"Adam wrote in message
...
Does anyone have any idea of why the jet stream is so far south at
the moment? I've just looked at the GFS forecast for this week and
it has the polar jet south of the UK later in the week, and it
doesn't seem to be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

FWIIW, I do not think it is a direct consequence of global warming,
as I would have expected GW to move the Jet Stream northwards.

I blame the extent of Arctic sea ice which was almost back to normal
during April:
http://nsidc.org/data/seaice_index/i...timeseries.png.

I don't see what effect such a blip could have. The extent soon
returned to being well below normal. In any case, "normal" is set
during the recent period of global warming and so is well below normal
itself. ;-)


It is just a matter of waiting for the JS to flip back north and then
the Barbaque Summer can begin :-)

OTOH, flpping the Jet Stream might lead to a European Monsoon.


We're already experiencing a European Monsoon. How much colder and
wetter do you want it to get?

I see that, over the past month, the N Atlantic SST pattern has
changed. The warm area that has been around for ages has been replaced
by a cold pool near 40N 40W. This would be associated with higher than
usual pressure near Iceland and a positioning of the jet stream south
of its usual position.


I've never seen snow in lowland England in July. Hoping for a sub
528dam air to be over us by July.

On Jun 6, 8:15*am, "N_Cook" wrote:
Adam Lea wrote in message

...

Does anyone have any idea of why the jet stream is so far south at the
moment? I've just looked at the GFS forecast for this week and it has
the polar jet south of the UK later in the week, and it doesn't seem to
be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

Or to put it the other way, I'd like to know why "our" jetstream passes over
the UK for
( my guess as I've not found figures for it) about 80 percent of the time ,
we being a relatively small section of available latitude on the globe.

The latitude available to the jet stream is not the entire
hemisphere, let alone the globe. The midlatitude jet tends to blow at
the approximate latitude of greatest temperature contrast throughout
the depth of the troposphere. Unfortunately, we're in or near that
zone and will be until the next Ice Age, when the zone will shift
south leaving us free of disturbed weather, but frozen.

Tudor Hughes, Warlingham, Surrey.

Tudor Hughes wrote in message
...
On Jun 6, 8:15 am, "N_Cook" wrote:
Adam Lea wrote in message

...

Does anyone have any idea of why the jet stream is so far south at the
moment? I've just looked at the GFS forecast for this week and it has
the polar jet south of the UK later in the week, and it doesn't seem to
be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

Or to put it the other way, I'd like to know why "our" jetstream passes
over
the UK for
( my guess as I've not found figures for it) about 80 percent of the time
,
we being a relatively small section of available latitude on the globe.

The latitude available to the jet stream is not the entire
hemisphere, let alone the globe. The midlatitude jet tends to blow at
the approximate latitude of greatest temperature contrast throughout
the depth of the troposphere. Unfortunately, we're in or near that
zone and will be until the next Ice Age, when the zone will shift
south leaving us free of disturbed weather, but frozen.

Tudor Hughes, Warlingham, Surrey.

++++++


or our globe east-west spin rate goes up or slows down, so our perceived
west-east view of the most outer layers of the atmosphere , ie the initiator
of the jet stream is obliged to move north or south

N_Cook wrote:
Tudor Hughes wrote in message
...
On Jun 6, 8:15 am, "N_Cook" wrote:
Adam Lea wrote in message

...

Does anyone have any idea of why the jet stream is so far south at
the moment? I've just looked at the GFS forecast for this week and
it has the polar jet south of the UK later in the week, and it
doesn't seem to be in any hurry to move away from that latitude.

What atmospheric processes are capable of shifting the jet stream
further north, closer to where it should be for the time of year?

Or to put it the other way, I'd like to know why "our" jetstream
passes over the UK for
( my guess as I've not found figures for it) about 80 percent of the
time , we being a relatively small section of available latitude on
the globe.

The latitude available to the jet stream is not the entire
hemisphere, let alone the globe. The midlatitude jet tends to blow at
the approximate latitude of greatest temperature contrast throughout
the depth of the troposphere. Unfortunately, we're in or near that
zone and will be until the next Ice Age, when the zone will shift
south leaving us free of disturbed weather, but frozen.

Tudor Hughes, Warlingham, Surrey.

++++++


or our globe east-west spin rate goes up or slows down, so our
perceived west-east view of the most outer layers of the atmosphere ,
ie the initiator of the jet stream is obliged to move north or south

Well the earth is slowing down due to tidal drag but over periods
of hundreds of millions of years.
--
Col

Bolton, Lancashire
160m asl