The devil is in the detail. Both models have the split polar vortex over
western Siberia and Baffin Island. But ECM develops the polar high into
Greenland far more than GFS. Hence energy is diverted southwards in ECM but
not in GFS. UKMO is similar to EC. Obviously within that broad scenario
there are a range of solutions EC and UKMO will have a range of cold
solutions whereas GFS will go predominantly mild since a vortex over Baffin
Island without a strong arctic ridge into Greenland is a zonal setup. My
question is what is the resolution in the stratosphere in the GFS compared
to EC or UKMO? I suspect that there are fewer levels but am I right? Anyone
know?
MetO seem to be going along with UKMet model in the short term which is
sensible I think.

Will
--
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------

On Jan 10, 9:35*am, "Eskimo Will" wrote:
The devil is in the detail. Both models have the split polar vortex over
western Siberia and Baffin Island. But ECM develops the polar high into
Greenland far more than GFS. Hence energy is diverted southwards in ECM but
not in GFS. UKMO is similar to EC. Obviously within that broad scenario
there are a range of solutions EC and UKMO will have a range of cold
solutions whereas GFS will go predominantly mild since a vortex over Baffin
Island without a strong arctic ridge into Greenland is a zonal setup. My
question is what is the resolution in the stratosphere in the GFS compared
to EC or UKMO? I suspect that there are fewer levels but am I right? Anyone
know?
MetO seem to be going along with UKMet model in the short term which is
sensible I think.

Will
--http://www.lyneside.demon.co.uk/Haytor/automatic/Current_Vantage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------

64 levels in GFS compared to the 70 of UKMO model according to
http://en.wikipedia.org/wiki/Global_Forecast_System

Not sure where the lid is though.

Forecasts for North America certainly mention it though:

THE SECOND PATTERN CHANGE WILL BEGIN TO SHOW ITS CARDS BY THE MIDDLE
OF THE MONTH. A MAJOR SUDDEN STRATOSPHERIC WARMING EVENT IS UNDERWAY
AND NEARING COMPLETION. SUDDEN STRATOSPHERIC WARMING EVENTS ARE
FAVORED TO OCCUR DURING AN EASTERLY PHASE OF THE QUASI-BIENNIAL
OSCILLATION /QBO/...WHICH IS THE PHASE THE STRATOSPHERE IS IN THIS
WINTER. THE SUDDEN STRATOSPHERIC WARMING CAUSES A DRAMATIC
WEAKENING...AND SOMETIMES ENTIRE BREAKDOWN OF THE STRATOSPHERIC
POLAR VORTEX...AND A GREAT WEAKENING OR EVEN REVERSAL OF THE
STRATOSPHERIC POLAR NIGHT JET. THE GFS FORECASTS THIS TO OCCUR OVER
THE NEXT WEEK AT THE 2MB LEVEL.

THE RESULT OF ALL OF THIS IS THE GENERATION OF STRONG HIGH LATITUDE
BLOCKING AS THE DRAMATIC CHANGES IN THE STRATOSPHERE FEED DOWN INTO
THE TROPOSPHERE. HIGH LATITUDE BLOCKING FORCES THE COLDEST AIR SOUTH
OUT OF THE HIGH ARCTIC AND TOWARDS THE MID LATITUDES...AND ALSO
FAVORS LASTING STRONGLY NEGATIVE EPISODES OF ARCTIC OSCILLATION /AO/
AND NORTH ATLANTIC OSCILLATION /NAO/. THIS TYPICALLY BEGINS TO TAKE
PLACE 10-15 DAYS AFTER THE SUDDEN STRATOSPHERIC WARMING EVENT. HOW
LONG IT LASTS CAN VARY...BUT TYPICALLY THE COLD PATTERN LASTS FOR AT
LEAST A FEW WEEKS...AND OCCASIONALLY CAN PERSIST THROUGH THE REST OF
WINTER.

AS ALL OF THIS IS OCCURRING...THE MJO IS FORECAST BY THE GEFS
ENSEMBLES TO WEAKEN AND FADE AWAY IN ABOUT 10 DAYS. THE PACIFIC
NORTH AMERICAN PATTERN /PNA/ IS FORECAST TO REMAIN NEGATIVE OVER THE
NEXT 10 DAYS...WHICH WILL DIRECT THE FIRST BATCHES OF COLD INTO THE
WESTERN AND EVENTUALLY CENTRAL UNITED STATES. GEFS ENSEMBLE MEMBERS
SUPPORT A TREND TOWARDS A NEUTRAL OR POSITIVE PNA BY THE MIDDLE OF
THE MONTH...WHICH SHOULD ALLOW THE GROWING COLD TO SPREAD EASTWARD.

Len
Wembury

In article ,
Eskimo Will writes:
The devil is in the detail. Both models have the split polar vortex
over western Siberia and Baffin Island. But ECM develops the
polar high into Greenland far more than GFS. Hence energy is
diverted southwards in ECM but not in GFS. UKMO is similar to EC.
Obviously within that broad scenario there are a range of solutions
EC and UKMO will have a range of cold solutions whereas GFS
will go predominantly mild since a vortex over Baffin Island
without a strong arctic ridge into Greenland is a zonal setup. My
question is what is the resolution in the stratosphere in the GFS
compared to EC or UKMO? I suspect that there are fewer levels but
am I right? Anyone know?
MetO seem to be going along with UKMet model in the short term
which is sensible I think.

Will

Even with the GFS, the 0Z ensemble indicates that - after a milder
interlude around Thursday-Friday next week - it could turn colder again,
with the operational run being one of the milder members though not a
true outlier. Interestingly, the control run - using identical data to
the operational run but running at lower resolution than it as far as
(IIRC) T+240 - shows exceptional cold in the latter part of its run. So
even with the GFS, it must be pretty finely balanced.
--
John Hall

"Whenever people agree with me I always feel I must be wrong."
Oscar Wilde

In article
,
Len Wood writes:
Forecasts for North America certainly mention it though:
snip

That's excellent. What a pity that the UKMO and ECMWF don't produce
anything like this for public consumption. (I'm sure that they must do
it internally.)
--
John Hall

"Whenever people agree with me I always feel I must be wrong."
Oscar Wilde

Will model specs:

GFS
64 unequally-spaced sigma levels For a surface pressure of 1000 hPa, 15
levels are below 800 hPa, and 24 levels are above 100 hPa with the top level
at .3 hPa. New version will go to 91 levels.

Met Office 70 levels total top about 80KM (small fraction of hPa) not sure
how many above 100 Hpa

ECMWF L91 version has about 38 levels above 100 hPa and the new L137 has
about 60 levels about 100 hPa

"Mike.Trigger" wrote in message
...
Will model specs:

GFS
64 unequally-spaced sigma levels For a surface pressure of 1000 hPa, 15
levels are below 800 hPa, and 24 levels are above 100 hPa with the top
level at .3 hPa. New version will go to 91 levels.

Met Office 70 levels total top about 80KM (small fraction of hPa) not sure
how many above 100 Hpa

ECMWF L91 version has about 38 levels above 100 hPa and the new L137 has
about 60 levels about 100 hPa


Cheers Mike.
Seems ECM resolves strat. quite well in comparison to GFS.

Will
--
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
---------------------------------------------