Today's model interpretation (18/01/06)
 

Here is a summary of the latest NWP output for noon on Saturday. Issued
0550, 17 Jan 06.

The models are split today. The minor ones show a mobile setup with
westerlies or SW'lies and rain for all at times. ECM, MetO and GFS instead
show a NW/SE split with high pressure keeping things settled for much of
England and Wales. Assuming the "big three" are correct, England and Wales
would thus see lower temperatures than Northern Ireland and Scotland, which
would remain under more of a maritime influence.
Beyond that things are less certain, not least due to a large chunk of very
cold air to our NE. GFS brings that cold air across the UK in spectacular
style (-18C 850s and 500dam air for Kent by T+300). As you'd expect, it was
a complete outlier with its temperatures, but a small number of ensemble
members show a similar evolution.

ECMWF: http://217.160.75.104/pics/Recm1201.gif
A weak ridge covers the UK, bringing a mixture of westerlies and WSW'lies.
Much the same is true at T+144, followed by southerlies at T+168 as pressure
rises to the east.

MetO: http://217.160.75.104/pics/Rukm1201.gif
MetO brings a ridge over England and Wales with light winds there. Elsewhere
winds are SW'lies, followed by similar conditions at T+144.

GFS: http://217.160.75.104/pics/Rtavn1201.png
A large high covers England, Wales and France. This leads to light winds
over England and Wales, with SW'lies for Scotland and Northern Ireland.
There's little change at T+144, but by T+168 winds become SE'lies and
southerlies for England and Wales as the high merges with a larger high to
the east. Scotland lies under SW'lies and Northern Ireland is affected by
southerlies.

GEM: http://meteocentre.com/models/glb00_120.html
The Canadian run shows SW'lies for all, with the UK between a high to the SE
and low pressure to the NW.

GME/DWD:
http://www.wetter.com/home/img/sat/g...160000_120.gif
Unavailable today.

JMA: http://217.160.75.104/pics/Rjma1201.gif
The Japanese run shows an area of high pressure over Biscay, with westerlies
as a result across the UK. The winds become a mixture of westerlies and
WSW'lies at T+144 as the high moves eastwards.

NOGAPS: http://217.160.75.104/pics/ngp10.prp.120.europeg.gif
NOGAPS shows strong westerlies with a similar synoptic setup to JMA.

KMA: http://www.kma.go.kr/kma03/gif/g21nh_smsr_120.gif
As with JMA and NGP, the Korean run shows strong westerlies across the UK
with high pressure to the south.

Today's model interpretation (18/01/06)
 

On Tue, 17 Jan 2006 05:52:46 -0000, "Darren Prescott"
wrote:

Here is a summary of the latest NWP output for noon on Saturday. Issued
0550, 17 Jan 06.

The models are split today. The minor ones show a mobile setup with
westerlies or SW'lies and rain for all at times. ECM, MetO and GFS instead
show a NW/SE split with high pressure keeping things settled for much of
England and Wales. Assuming the "big three" are correct, England and Wales
would thus see lower temperatures than Northern Ireland and Scotland, which
would remain under more of a maritime influence.
Beyond that things are less certain, not least due to a large chunk of very
cold air to our NE. GFS brings that cold air across the UK in spectacular
style (-18C 850s and 500dam air for Kent by T+300). As you'd expect, it was
a complete outlier with its temperatures, but a small number of ensemble
members show a similar evolution.

ECMWF: http://217.160.75.104/pics/Recm1201.gif
A weak ridge covers the UK, bringing a mixture of westerlies and WSW'lies.
Much the same is true at T+144, followed by southerlies at T+168 as pressure
rises to the east.

MetO: http://217.160.75.104/pics/Rukm1201.gif
MetO brings a ridge over England and Wales with light winds there. Elsewhere
winds are SW'lies, followed by similar conditions at T+144.

GFS: http://217.160.75.104/pics/Rtavn1201.png
A large high covers England, Wales and France. This leads to light winds
over England and Wales, with SW'lies for Scotland and Northern Ireland.
There's little change at T+144, but by T+168 winds become SE'lies and
southerlies for England and Wales as the high merges with a larger high to
the east. Scotland lies under SW'lies and Northern Ireland is affected by
southerlies.

GEM: http://meteocentre.com/models/glb00_120.html
The Canadian run shows SW'lies for all, with the UK between a high to the SE
and low pressure to the NW.

GME/DWD:
http://www.wetter.com/home/img/sat/g...160000_120.gif
Unavailable today.

JMA: http://217.160.75.104/pics/Rjma1201.gif
The Japanese run shows an area of high pressure over Biscay, with westerlies
as a result across the UK. The winds become a mixture of westerlies and
WSW'lies at T+144 as the high moves eastwards.

NOGAPS: http://217.160.75.104/pics/ngp10.prp.120.europeg.gif
NOGAPS shows strong westerlies with a similar synoptic setup to JMA.

KMA: http://www.kma.go.kr/kma03/gif/g21nh_smsr_120.gif
As with JMA and NGP, the Korean run shows strong westerlies across the UK
with high pressure to the south.



Perhaps it's that time when we can say "summat's up!"

Today's model interpretation (18/01/06)
 

Scott Whitehead wrote:

Perhaps it's that time when we can say "summat's up!"

I hope so. Starting to feel a bit depressed with not seeing the sun for
many a day. Having said that, we really, really need some more rain here
- just 13.7mm so far this month.

--
Jonathan Stott
Canterbury Weather: http://www.canterburyweather.co.uk/
Reverse my e-mail address to reply by e-mail

Today's model interpretation (18/01/06)
 

500dam air for Kent by T+300). As you'd expect, it was a complete
outlier with its temperatures, but a small number of ensemble members
show a similar evolution.

Is there any simple way to convert thickness (see, I think I've learned
something here) to likely surface maxima and minima?

Trevor

Today's model interpretation (18/01/06)
 

"Jonathan Stott" wrote in message
...
Scott Whitehead wrote:

Perhaps it's that time when we can say "summat's up!"

I hope so. Starting to feel a bit depressed with not seeing the sun for
many a day. Having said that, we really, really need some more rain here -
just 13.7mm so far this month.

--


I'll second that one and I think most of us feel the same. We must still be
on single figures for sunshine. Its dreadful , and yet another gloomy day.

Gavin.

Today's model interpretation (18/01/06)
 

On Tue, 17 Jan 2006 11:08:10 -0000, "Gavin Staples"
wrote:


"Jonathan Stott" wrote in message
...
Scott Whitehead wrote:

Perhaps it's that time when we can say "summat's up!"

I hope so. Starting to feel a bit depressed with not seeing the sun for
many a day. Having said that, we really, really need some more rain here -
just 13.7mm so far this month.

--


I'll second that one and I think most of us feel the same. We must still be
on single figures for sunshine. Its dreadful , and yet another gloomy day.

Gavin.

wasn't January 1991 exceptionally dull and "rather cold". Of course
the February that followed produced the most exceptional snowfall I've
seen in the South East. Knee-deep level snow - but with a notable lack
of wind. Had this been accompanied by a breeze, the snowdrifts would
have been remarkable...

Today's model interpretation (18/01/06)
 

"Trevor Harley" wrote in message
news:2006011709535616807-taharley@dundeeacuk...

Is there any simple way to convert thickness (see, I think I've
learned something here) to likely surface maxima and minima?


.... The thickness value (500-1000 hPa/TTHK) is one of the *worst*
parameters to use to try and forecast surface temperature data,
particularly for winter, continental situations (and airmasses coming
out of such areas).

The problem is very well illustrated by the situation over east and
northern Poland at the moment:
Using the 12Z radiosonde data yesterday (Tuesday) from Legionowo
(12374), the thickness value is given as 5319m (or 532 dam).

Day-time maxima across a large swathe of north, central and eastern
Poland yesterday (Tuesday) were generally -6 to -8degC. Yet 532 dam is
hardly a very low thickness value. If it were to 'obey' a standard (ISA)
profile, you might be expecting a screen maximum around 4degC.

The key of course lies in the snow-cover over eastern Europe. If you
look at the ascent here

( http://makeashorterlink.com/?G29A25C7C )

you'll see that the lowest few hundred metres of the troposphere has
become totally divorced (or decoupled) from the 'main' ascent, and heat
exchanges (radiation/conduction) are occurring without reference to what
is happening higher up. Note also that the 850hPa level is also just
above the boundary-layer region, so even using 850 hPa temperatures
could lead you astray (this applies to such as 850-1000 hPa thicknesses
of course).

Will was talking about this in his summary of the situation: by all
means use the TTHK values as a 'first guess' to chase the broadscale
airmass changes around the synoptic map, but in these situations where
the character of the surface is highly important, then it is best to use
a 'tracer' at much lower levels (if available) such as 900 hPa.

Martin.


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