Darren Prescott drew our attention to a possible northerly airstream
for the coming weekend and this possibility is worth checking.

The forecast 500 mb-chart for 18th September '03 shows a long tongue of
cold air stretching from the top of Scandinavia in a SW direction to
the SW of Iceland. It seems to be brought about by a long chain of
NE winds coming out of the Arctic Ocean north of Scandinavia.

As the cold trough swings E'wards towards the British Isles from 18th
to 20th September, warm air drifts from Spain NE'wards towards N
Germany.

On 21st, the cold air from the trough lies just to the W of Britain
and I expect the cold front to be just on the W coast of Ireland. At
the same time, a tongue of warm air is drawn NNW'wards from N Germany up
the N Sea to the W of Norway, thus turning the axis of the cold trough
over the Atlantic in a N-S direction as it approaches Ireland.

On 22nd September the cold air should cover the British Isles with
winds from a NW direction.

On 23rd, warmer atlantic air approaches the British Isles from the W.
By the 24th a HP builds up over the SW of Britian in front of a LP over
mid-Atlantic and draws warmer ait into Europe over the next 3 or 4
days.

So this one appears to be only a small, cold period from the NW.

Cheers, Keith

================================================== ==================
This posting expresses the personal view and opinions of the author.
Something which everyone on this planet should be able to do.
================================================== ==================

I'd hardly call it cold Keith, not with sea temps circa 3 deg C above normal in
northern latitudes, and it is only still September.

Will.
--
" Love begins when judgement ceases "
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Keith Darlington wrote in message ...
Darren Prescott drew our attention to a possible northerly airstream
for the coming weekend and this possibility is worth checking.

The forecast 500 mb-chart for 18th September '03 shows a long tongue of
cold air stretching from the top of Scandinavia in a SW direction to
the SW of Iceland. It seems to be brought about by a long chain of
NE winds coming out of the Arctic Ocean north of Scandinavia.

As the cold trough swings E'wards towards the British Isles from 18th
to 20th September, warm air drifts from Spain NE'wards towards N
Germany.

On 21st, the cold air from the trough lies just to the W of Britain
and I expect the cold front to be just on the W coast of Ireland. At
the same time, a tongue of warm air is drawn NNW'wards from N Germany up
the N Sea to the W of Norway, thus turning the axis of the cold trough
over the Atlantic in a N-S direction as it approaches Ireland.

On 22nd September the cold air should cover the British Isles with
winds from a NW direction.

On 23rd, warmer atlantic air approaches the British Isles from the W.
By the 24th a HP builds up over the SW of Britian in front of a LP over
mid-Atlantic and draws warmer ait into Europe over the next 3 or 4
days.

So this one appears to be only a small, cold period from the NW.

Cheers, Keith

"Keith Darlington" wrote in message
...

"Next cold period" - you say it like we've had one recently !

Joe

In uk.sci.weather on Sun, 14 Sep 2003 at 14:15:15, Keith Darlington
wrote :
Darren Prescott drew our attention to a possible northerly airstream
for the coming weekend and this possibility is worth checking.

On 22nd September the cold air should cover the British Isles with
winds from a NW direction.

On 23rd, warmer atlantic air approaches the British Isles from the W.
By the 24th a HP builds up over the SW of Britian in front of a LP over
mid-Atlantic and draws warmer ait into Europe over the next 3 or 4
days.

So this one appears to be only a small, cold period from the NW.

Us cold-weather-lovers are also straw-clutchers.

Cold enough for the first ground-frost this autumn?

BTW, on the Wettercarte pressure maps, what does the black line to the N
of Britain represent? Is it a jet stream?
--
Paul Hyett, Cheltenham, England

"Paul Hyett" wrote in message
...
snip
BTW, on the Wettercarte pressure maps, what does the black line to the
N
of Britain represent? Is it a jet stream?

.... I think you are looking at the 552dam contour (used to track major
long-wave pattern changes) - see the link below for more on output from
various centres with examples, explanation etc.

http://homepage.ntlworld.com/booty.w...dels/sites.htm

Martin.

In uk.sci.weather on Mon, 15 Sep 2003 at 07:31:47, martin rowley wrote :

... I think you are looking at the 552dam contour (used to track major
long-wave pattern changes) - see the link below for more on output from
various centres with examples, explanation etc.

http://homepage.ntlworld.com/booty.w...dels/sites.htm

Thanks for this - very useful.

Just one question : If hPa is the same as millibars (as seems to be the
case), why have two names for it? It's like Celcius & Centigrade.
--
Paul Hyett, Cheltenham, England

Paul Hyett wrote:
Just one question : If hPa is the same as millibars
(as seems to be the case), why have two names for it?

They are not the same, they just appear to be because 1 hPa = 1
millibar. The bar is one of the old units for pressure. The pascal is
the SI unit.


It's like Celcius & Centigrade.

Those were two names for the same thing. The word Centigrade was
officially dropped in 1948. The correct name is Celsius.


As with general conversion to the metric system, transition takes time
and effort. The hPa replaced the millibar as the legal unit of
pressure for UK aviation in 1996, but the hPa value must still be
described as 'millibars' in spoken communication between ground and
air.


Lots of stuff about units at the official SI website:
www1.bipm.org/en/si/derived_units/2-2-2.html

On 6 Oct 2003 03:48:58 -0700, (Pat Norton) wrote:


As with general conversion to the metric system, transition takes time
and effort. The hPa replaced the millibar as the legal unit of
pressure for UK aviation in 1996, but the hPa value must still be
described as 'millibars' in spoken communication between ground and
air.

So why bother changing the name at all? New names (when the unit
remains the same) are usually (if not always) arbitrary and
scientifically unecessary. Such changes invariably lead to confusion
or at least unecessary duplication for many years longer than the
initiators of such changes predicted. Confusion and duplication cost
time and money not only among scientists but in business and among the
general public.

More than two generations after you say the change was officially
made, the name Centigrade is still used quite a bit by the general
public. I rest my case.

--
Dave

(Pat Norton) wrote in message m...
Paul Hyett wrote:
Just one question : If hPa is the same as millibars
(as seems to be the case), why have two names for it?

They are not the same, they just appear to be because 1 hPa = 1
millibar. The bar is one of the old units for pressure. The pascal is
the SI unit.


It's like Celcius & Centigrade.

Those were two names for the same thing. The word Centigrade was
officially dropped in 1948. The correct name is Celsius.

There was also a third name, centesimal degrees, when the CGPM chose
from among the three names then in use in 1948.

As with general conversion to the metric system, transition takes time
and effort. The hPa replaced the millibar as the legal unit of
pressure for UK aviation in 1996, but the hPa value must still be
described as 'millibars' in spoken communication between ground and
air.

It wouldn't take half as long if they had used the normal, preferred
SI prefixes, as Canada does with kilopascals in its weather reports,
rather than some obscure, little known, useless prefix which is not a
power of 1000. Those hectopascals also violate another, weaker
preference for having most numbers in the range of 0.1 to 1000.

If you'd had to move the decimal point, then you can be damn sure that
there would have been a concerted effort to get the word out that
there had been a change, and you wouldn't be dicking around with the
obsolete name so many years later.

Gene Nygaard

Dave Ludlow wrote:
So why bother changing the name at all?

That sounds like "Why SI?". Note that there are many different units
of pressu
pascal
bar
atmosphere
inch of water
mm of water
inch of mercury
mm of mercury
foot of water
pound per square inch
pound per square foot
ton(UK) per square foot
ton(US) per square foot

Aviation has been using multiple units for weather (inch of mercury,
pascal, bar). More units are in legal and technical specificiations
(pound/inch², ton/inch²). Units of measurement for aviation are of
international importance and agreed via ICAO. It has compiled a
standard set of units:

"The standardized system is based on the International System of Units
(SI) and will eventually eliminate the use of different units of
measurement for the same quantity and provide for the standardized
application of all units of measurement for those quantities used in
air and ground operations."
www.icao.int/icao/en/pub/memo.htm