I'm off to the Alps in a week and as such have been examining the GFS
Ensembles. I've noticed that the ensembles have been quite consistent
with high pressure expected to build to the north/west [of the Alps]
allowing cooler/colder conditions to prevail.

Yet the actual operational run seems to be quite keen to maintain the
high over Spain with, no ridge to the north, [and bring freezing
levels up to nearly 3000m, not good for skiing] On a number of
occasions is has been a clear outlier.

Is there any explanation for this? Does the operational run, over
time, hold greater weight over the other perturbations? Should I be
nervous about getting ‘milded out’

In article
,
writes:
I'm off to the Alps in a week and as such have been examining the GFS
Ensembles. I've noticed that the ensembles have been quite consistent
with high pressure expected to build to the north/west [of the Alps]
allowing cooler/colder conditions to prevail.

Yet the actual operational run seems to be quite keen to maintain the
high over Spain with, no ridge to the north, [and bring freezing
levels up to nearly 3000m, not good for skiing] On a number of
occasions is has been a clear outlier.

Is there any explanation for this? Does the operational run, over
time, hold greater weight over the other perturbations? Should I be
nervous about getting ‘milded out’

I believe the operational run uses a finer grid for its calculations and
so, other things being equal, should be given more weight that
individual ensemble members. But if 80% or 90% of ensemble members are
going for something different from the operational run, then they are
quite likely to be right. After all, a purpose of the ensemble is
presumably to indicate occasions when the operational run is likely to
be wrong.
--
John Hall
"Honest criticism is hard to take,
particularly from a relative, a friend,
an acquaintance, or a stranger." Franklin P Jones

"John Hall" wrote in message
...
In article
,
writes:
I'm off to the Alps in a week and as such have been examining the GFS
Ensembles. I've noticed that the ensembles have been quite consistent
with high pressure expected to build to the north/west [of the Alps]
allowing cooler/colder conditions to prevail.

Yet the actual operational run seems to be quite keen to maintain the
high over Spain with, no ridge to the north, [and bring freezing
levels up to nearly 3000m, not good for skiing] On a number of
occasions is has been a clear outlier.

Is there any explanation for this? Does the operational run, over
time, hold greater weight over the other perturbations? Should I be
nervous about getting 'milded out'

I believe the operational run uses a finer grid for its calculations and
so, other things being equal, should be given more weight that
individual ensemble members. But if 80% or 90% of ensemble members are
going for something different from the operational run, then they are
quite likely to be right. After all, a purpose of the ensemble is
presumably to indicate occasions when the operational run is likely to
be wrong.
--
John Hall
"Honest criticism is hard to take,
particularly from a relative, a friend,
an acquaintance, or a stranger." Franklin P Jones
-------------------------
If you're not going for seven days or more my advice would be to completely
ignore it because it will change massively every day. Wait till 3 days
before then you won't be disappointed.
Dave

On Jan 14, 12:28 pm, wrote:

I'm off to the Alps in a week and as such have been examining the GFS
Ensembles. I've noticed that the ensembles have been quite consistent
with high pressure expected to build to the north/west [of the Alps]
allowing cooler/colder conditions to prevail.

Yet the actual operational run seems to be quite keen to maintain the
high over Spain with, no ridge to the north, [and bring freezing
levels up to nearly 3000m, not good for skiing] On a number of
occasions is has been a clear outlier.

Is there any explanation for this? Does the operational run, over
time, hold greater weight over the other perturbations? Should I be
nervous about getting 'milded out'

15th Jan (19:46) So this is the last day of a most interesting spell.

Unfortunately the next one is somewhat similar, so expect very little
change in the GEM and GFS charts.

11:37 is as near to 12:00 as 19:46 is to 18:00 and damn it is to
swearing.
And the expected situation on this chart:
http://weather.unisys.com/images/sat_sfc_map_loop.html
at these times is:

A standing Low Pressure area situated somewhat to the left of the
Great Lakes.

With a complex set of High pressure areas trying to break through from
the west.
http://groups.google.com/group/sci.g...6a556cd238f8e3