Hi Mike
Symbols appeared to be OK here ... no problems at all.
Thanks all for the very interesting thread...
Cheers
John
--
York,
North Yorkshire.
(Norman Virus Protected)

"Mike Tullett" wrote in message
...
On Sat, 10 Jan 2004 08:58:11 -0000, PJB wrote in


Thanks Paul, I'm OK on the low level baroclinic zone. Could you just
amplify
the last sentence. What is a 'shortwave Upper Trough' is this just a
'trough' of low pressure, but at altitude and not necessarily at the
surface?

Yes Phil a shortwave is a trough of low pressure at a certain height
(say
300mb) it is called a shortwave becuase it is much smaller than a
typical
"long wave" upper trough which stretch for thousands of miles (such as
when
we are in an omega block - that is the longwave pattern) a shortwave is
a
much smaller feature, but it can provide the required forcing to deepen
a
low very quickly.

It's also worth noting these "short waves" typically move faster [1] than
the long waves in which they are embedded. The latter can almost be
thought of as quasi-stationary in many situations, with the shorter ones
moving through them. There is a slight analogy with ocean waves [2] where
the long waves move at greater speed than the short waves.

[1] The speed of wave movement "c" is given by the Rossby Equation:

c = U - L?²/4?²

Where U is wind speed within the wave, ? is ?f/?y a measure of how fast
the
coriolis effect (parameter) is changing with latitude and L is latitude.
This formula shows the importance of wavelength. When it exceeds a
certain
figure, c goes negative and the wave retrogresses - goes back to the west.

[2] The major difference between the two types of wave is that motion
within an atmospheric wave is largely horizontal, whilst that of an ocean
wave is vertical.

Apoligies if the symbols don't show up correctly. This is my first
attempt
at using the Windows Character Map.

--
Mike 55.13°N 6.69°W Coleraine posted to uk.sci.weather 10/01/2004
09:43:26 UTC
My aurora images here http://www.mtullett.plus.com/29a-oct and
http://www.mtullett.plus.com/20-nov/

Joe Hunt wrote:


The culprit is just off Florida as we speak -

http://www.wetterzentrale.de/pics/nws1.html

Joe




Sorry to be thick - which low is the culprit?
This has been a fascinating thread - very educational ))
Sarah H

On Sat, 10 Jan 2004 18:54:27 +0000, SarahH
wrote:

Joe Hunt wrote:


The culprit is just off Florida as we speak -

http://www.wetterzentrale.de/pics/nws1.html

Sorry to be thick - which low is the culprit?
This has been a fascinating thread - very educational ))
Sarah H

Going by what Joe said, it'll be attached to that long wavy front
starting about 1000 miles West of Ireland and stretching S and West
until it touches the S. tip of Florida. HTH,

--
Dave

Dave Ludlow wrote:


http://www.wetterzentrale.de/pics/nws1.html


Sorry to be thick - which low is the culprit?
This has been a fascinating thread - very educational ))
Sarah H


Going by what Joe said, it'll be attached to that long wavy front
starting about 1000 miles West of Ireland and stretching S and West
until it touches the S. tip of Florida. HTH,


Thanks! I was wondering exactly which one 'cos there seems to be a
little line of lows. Its about time I did some proper reading and
learned for myself......

Sarah H

"SarahH" wrote in message
...


Thanks! I was wondering exactly which one 'cos there seems to be a
little line of lows. Its about time I did some proper reading and
learned for myself......

.... it's not a daft question this: the problem will be to pick out the
*significant* development from the 'runners' (the ones that don't cross
to the cold side of the jet and develop sharply). The situation this
morning still looks a mess
( see: http://www.weather.org.uk/charts/UKCpf000.gif .. all those
'wiggly bits' south of Newfoundland - which one is the 'fat lady'?)

and the 'window' of uncertainty is open as wide as it could be! I think
Bob Prichard got it about as right as possible this morning (on Radio 5)
when he went more for the rain, but also saying that the nearer to the
English Channel you were, the more likely to have to worry about wind -
and of course it's pretty lively now in some places as regards wind.
(And in north coastal France & the Channel Islands, the strength of the
wind almost certainly will be uppermost; indeed, have just looked at the
latest Arpege output on MF site, and at VT 12/1200Z, there is a 60kn
arrow (mean wind) slap-bang in area Wight, with a discrete area of dark
red (55kn upwards in the central Channel), so the 'watch' for the
broader English Channel (including the south English coastal areas east
of roughly Start Point) is still valid.

For those that don't know, you can keep an eye on the Buoy data at the
following link (click on the appropriate sub-map for either the UK or
French sectors)

http://www.ndbc.noaa.gov/

Martin.

Martin Rowley wrote in message ...

"SarahH" wrote in message
...


Thanks! I was wondering exactly which one 'cos there seems to be a
little line of lows. Its about time I did some proper reading and
learned for myself......

... it's not a daft question this: the problem will be to pick out the
*significant* development from the 'runners' (the ones that don't cross
to the cold side of the jet and develop sharply). The situation this
morning still looks a mess
( see: http://www.weather.org.uk/charts/UKCpf000.gif .. all those
'wiggly bits' south of Newfoundland - which one is the 'fat lady'?)

and the 'window' of uncertainty is open as wide as it could be! I think
Bob Prichard got it about as right as possible this morning (on Radio 5)
when he went more for the rain, but also saying that the nearer to the
English Channel you were, the more likely to have to worry about wind -
and of course it's pretty lively now in some places as regards wind.
(And in north coastal France & the Channel Islands, the strength of the
wind almost certainly will be uppermost; indeed, have just looked at the
latest Arpege output on MF site, and at VT 12/1200Z, there is a 60kn
arrow (mean wind) slap-bang in area Wight, with a discrete area of dark
red (55kn upwards in the central Channel), so the 'watch' for the
broader English Channel (including the south English coastal areas east
of roughly Start Point) is still valid.

For those that don't know, you can keep an eye on the Buoy data at the
following link (click on the appropriate sub-map for either the UK or
French sectors)

http://www.ndbc.noaa.gov/

Martin.



Thanks Martin, it's going to be a very close run thing for me up at 1000 feet.
70 mph I can cope with as that is not unusual in these parts, but 90-100 mph
that could cause damage. Fortunately the land rises to the west of my house so
unless there is a rotor (unlikely) I should still have a roof tomorrow,
hopefully.

Ah well I did choose to live up here !

Will.
--

" A cup is most useful when empty "
-------------------------------------------------------------------------------
A COL BH site in East Dartmoor at Haytor, Devon 310m asl (1017 feet).

mailto:
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DISCLAIMER - All views and opinions expressed by myself are personal
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-------------------------------------------------------------------------------

Martin Rowley wrote:
... it's not a daft question this: the problem will be to pick out the
*significant* development from the 'runners' (the ones that don't cross
to the cold side of the jet and develop sharply). The situation this
morning still looks a mess
( see: http://www.weather.org.uk/charts/UKCpf000.gif .. all those
'wiggly bits' south of Newfoundland - which one is the 'fat lady'?)

snip a little

For those that don't know, you can keep an eye on the Buoy data at the
following link (click on the appropriate sub-map for either the UK or
French sectors)

http://www.ndbc.noaa.gov/

Martin.



Thankyou Martin! Its going to be an interesting time ahead. Its making
me realise how much goes into forecasting. I love the buoy data - I
hadnt seen that before, it will be fun watching them. Im going to tidy
the garden this afternoon just in case - Im at the top end of Hampshire.

Sarah H

In message , Will
writes


Snip

Thanks Martin, it's going to be a very close run thing for me up at 1000 feet.
70 mph I can cope with as that is not unusual in these parts, but 90-100 mph
that could cause damage. Fortunately the land rises to the west of my house so
unless there is a rotor (unlikely) I should still have a roof tomorrow,
hopefully.

Ah well I did choose to live up here !

Will.
--

It certainly is on a knife edge. The GFS model is persisting with its
more optimistic predictions. For this location the highest mean wind on
Monday from the 00z run is only 13 knots. I wouldn't like to rely on
that!.

Norman.
(delete "thisbit" twice to reply)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles
England