http://www.metoffice.gov.uk/research...l/gpc-outlooks

Not sure what stage we're in with these ... I assume that the last
couple of iterations at least (issues August & September) have the
benefit of the 'high-top', i.e., enhanced stratospheric modelling, and
thus the output indicated is most interesting.

Both August and September issues have fairly strong signals for
below-average temperatures over the 3-month periods NDJ & DJF (where
available from August run): looking at the ensemble mean output, the
indication are for departures from the mean of at least
-0.5degC/-1.0degC, and 'fringing' the SW (i.e., across the SW Approaches
& western Ireland) and also in the broad area Iceland - Faeroes -
Viking, the departure is circa -1.5degC. [Not sure what the climatology
period is ... might be 'model' climatology, i.e., based on hindcast runs
from 1989 - 2002 rather than a 'standard' dataset].

The usual caveats apply of course - high probabilities doesn't mean it's
going to happen - but two consecutive runs with a similar (and
reasonably strong) signal, and with the assimilitation of the
consistently anomalous SSTAs that we've seen as commented upon
elsewhere, these products are either going to be wildly wrong and
risible, or are in fact offering us a good steer on the season to come.

Martin.



--
Martin Rowley
West Moors/East Dorset UK

Martin Rowley wrote:

http://www.metoffice.gov.uk/research...l/gpc-outlooks

Not sure what stage we're in with these ... I assume that the last couple of
iterations at least (issues August & September) have the benefit of the
'high-top', i.e., enhanced stratospheric modelling, and thus the output
indicated is most interesting.

Both August and September issues have fairly strong signals for below-average
temperatures over the 3-month periods NDJ & DJF (where available from August
run): looking at the ensemble mean output, the indication are for departures
from the mean of at least -0.5degC/-1.0degC, and 'fringing' the SW (i.e.,
across the SW Approaches & western Ireland) and also in the broad area
Iceland - Faeroes - Viking, the departure is circa -1.5degC. [Not sure what
the climatology period is ... might be 'model' climatology, i.e., based on
hindcast runs from 1989 - 2002 rather than a 'standard' dataset].

The usual caveats apply of course - high probabilities doesn't mean it's
going to happen - but two consecutive runs with a similar (and reasonably
strong) signal, and with the assimilitation of the consistently anomalous
SSTAs that we've seen as commented upon elsewhere, these products are either
going to be wildly wrong and risible, or are in fact offering us a good steer
on the season to come.

Martin.

In contrast, the current products from the NCEP Climate Forecast System predict
below average temperatures for the British Isles area in October and a very
cold March but for the months in between (Nov-Feb) they show temperatures close
to average. Their averaging period is currently 1981-2006.

All of these products are best taken with a great big pinch of salt, though :-)

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.

On 16/09/12 15:52, Norman wrote:
Martin Rowley wrote:

http://www.metoffice.gov.uk/research...l/gpc-outlooks

Not sure what stage we're in with these ... I assume that the last couple of
iterations at least (issues August& September) have the benefit of the
'high-top', i.e., enhanced stratospheric modelling, and thus the output
indicated is most interesting.

Both August and September issues have fairly strong signals for below-average
temperatures over the 3-month periods NDJ& DJF (where available from August
run): looking at the ensemble mean output, the indication are for departures
from the mean of at least -0.5degC/-1.0degC, and 'fringing' the SW (i.e.,
across the SW Approaches& western Ireland) and also in the broad area
Iceland - Faeroes - Viking, the departure is circa -1.5degC. [Not sure what
the climatology period is ... might be 'model' climatology, i.e., based on
hindcast runs from 1989 - 2002 rather than a 'standard' dataset].

The usual caveats apply of course - high probabilities doesn't mean it's
going to happen - but two consecutive runs with a similar (and reasonably
strong) signal, and with the assimilitation of the consistently anomalous
SSTAs that we've seen as commented upon elsewhere, these products are either
going to be wildly wrong and risible, or are in fact offering us a good steer
on the season to come.

Martin.

In contrast, the current products from the NCEP Climate Forecast System predict
below average temperatures for the British Isles area in October and a very
cold March but for the months in between (Nov-Feb) they show temperatures close
to average. Their averaging period is currently 1981-2006.

All of these products are best taken with a great big pinch of salt, though :-)


I've been visiting a friend in hospital today and he said he read in the
Telegraph that the upcoming UK winter was expected to be mild and wet.

Place your bets now! :-)

On Sunday, September 16, 2012 9:27:04 PM UTC+1, Adam Lea wrote:


I've been visiting a friend in hospital today and he said he read in the

Telegraph that the upcoming UK winter was expected to be mild and wet.

=============

I can't find any such report in the Telegraph. If it exists I wonder who it is from.

By the way, ECMWF O/N/D forecast has milder probabilities than GloSea4; so, as Norman, says take with a pinch of salt.

Seasonal forecasts are hard enough anyway but we're looking at almost unprecedented teleconnections; such a strong -ve PDO and +ve AMO have only coincided once in about the last 100 years, for example. We have a weak (moderate at best) Modoki El Nino, which is early and already weakening further (possibly a hiatus but expected to peak early and become neutral through winter/early spring anyway). And Arctic sea ice melt is unprecedented.

I'm all for the UKMO extended model (it re-forecast the 2009-10 winter better than the standard model) but it won't be the be all and end all (I'm not sure how well it did at the time with the 2010-11 winter, particularly the early extreme cold). Models are bound to struggle.

Stephen.

"Martin Rowley" wrote in message
...
http://www.metoffice.gov.uk/research...l/gpc-outlooks

Not sure what stage we're in with these ... I assume that the last couple
of iterations at least (issues August & September) have the benefit of the
'high-top', i.e., enhanced stratospheric modelling, and thus the output
indicated is most interesting.

Both August and September issues have fairly strong signals for
below-average temperatures over the 3-month periods NDJ & DJF (where
available from August run): looking at the ensemble mean output, the
indication are for departures from the mean of at least -0.5degC/-1.0degC,
and 'fringing' the SW (i.e., across the SW Approaches & western Ireland)
and also in the broad area Iceland - Faeroes - Viking, the departure is
circa -1.5degC. [Not sure what the climatology period is ... might be
'model' climatology, i.e., based on hindcast runs from 1989 - 2002 rather
than a 'standard' dataset].

The usual caveats apply of course - high probabilities doesn't mean it's
going to happen - but two consecutive runs with a similar (and reasonably
strong) signal, and with the assimilitation of the consistently anomalous
SSTAs that we've seen as commented upon elsewhere, these products are
either going to be wildly wrong and risible, or are in fact offering us a
good steer on the season to come.

Martin.


The output charts to me would suggest Atlantic blocking or even Greenland
blocking with a lot of northerlies. Could be interesting in Copley! :-)

Will
--