20th November 2003 - special forecast
 

What's so special about a forecast?
- it's probably the only forecast of its kind, .
- it's a T+24 DAY forecast
- it's a special weather situation with potentially interesting
developement
- it's experimental and describes the weather variations down to 3
hours.

While completing the series of forecast charts for T+10 day to T+20
days, I came across the chart for 20th November 2003, which attracted
my attention straight away. because of a secondary depression coming
into the country from the SW which had every possibility of bringing
strong winds along with it.

The next step was to check the forecast 500mb-top to see what effect
the surface situation would have in the upper atmosphere. On the day
in question, the 00Z chart showed an upper-air, narrow trough stretching
N-S about the length and width of Britain, placed just down the W
Irish coast.

On the surface at 00Z, the charts show a medium sized depression just
to the W amd NW of Scotland with a trough southwards to the SW of
Ireland. Winds over the whole country are generally from the S. South
of Ireland - and to the SW of England - a secondary depression is
expected to move ENE, across England, and into the North Sea to be near
Holland on 21st November 2003 at 00Z.

According to the charts, I can be sure that a secondary depression.will
be present on or near the position indicated. What is difficult to
forecast, is the strength of the wind. Among other things, the
variation in actual temperature can alter the central pressure of the
secondary depression. The charts do suggest that the stronger winds
should be found over SW England rather than SE England., and that the
secondary depression should fill more and more as it moves into the
North Sea.

Following the depression across the country means forecasting at short
intervals. Usually 3 hour intervals don't show much change - especially
when forecasts such as these are already working at "noise level". But
it is just possible to pick out the position of the depression and this
I have done where some clarity has been evident..

At 0600Z, rain showers should cover N, NW and W Scotland. There is
the possibility of a thin belt of fine weather stretching from Ireland
to NE England. Further south, rain associated with the secondary
depression near S Wales and SW England should move towards the SE of
England. These condition described here are only valid for the time
0600Z. An hour later, features (such as the fine weather in the north)
could, accoring to past experience, change rapidly.

At 1200Z, the secondary depression should form a complex LP system from
S Wales (or thereabouts) to N Scotland. Strong winds should become
evident over S Ireland and SW and S England. How strong, I don't know.
Rainy weather can be expected over Scotland and the W of Britain.
Weather deteriorates from the W over E England.

At 1500Z, the secondary can be identified over the central part of S
England and the central Midlands. Rain showers can be found over most
of the country, but rising pressure and improving weather can be found
over S Ireland.

At 1800Z, the secondary should be approaching E Anglia with winds
turning WSW or W over S England. Heavy rain is possible over Scotland
and N Ireland. The best weather is over SW England.

At 2100 Z, high pressure pushes into the SW of England and pressure
rises generally over the whole country except the extreme W of
Scotland. The secondary should be in the North Sea on its way to
Holland and S Denmark. Fine, clear weather comes into the whole country
from the SW.

The descriptions I have given you are exactly what the charts show. I
know that if I add my own embellishments, the forecast would certainly
come off course. It is only by following the method implicitly that I
can hope the forecast will have some success.

Let's wait till 20th November 2003

Cheers, Keith.

20th November 2003 - special forecast
 

Sorry if I'm making a "faux pas" here in newsgroup etiqutte - but how the
hell can you forecast for 20th Nov - as an avid wind watcher for my sport
we're at odds with all the recent blocking of high pressure systems and the
in-accurate forecasting of wind over the past three months - only now, one
day in advance can we be reasonably confident that yet again we will not be
let down by the promise of strong winds and that a rogue high pressure
system will not get in the way of approaching wind....that is from the
SW.....for kite / wind surfers we're amazed at just how bad 5 day forecasts
have been of late!!

REgards
WC

"Keith Darlington" wrote in message
...
What's so special about a forecast?
- it's probably the only forecast of its kind, .
- it's a T+24 DAY forecast
- it's a special weather situation with potentially interesting
developement
- it's experimental and describes the weather variations down to 3
hours.

While completing the series of forecast charts for T+10 day to T+20
days, I came across the chart for 20th November 2003, which attracted
my attention straight away. because of a secondary depression coming
into the country from the SW which had every possibility of bringing
strong winds along with it.

The next step was to check the forecast 500mb-top to see what effect
the surface situation would have in the upper atmosphere. On the day
in question, the 00Z chart showed an upper-air, narrow trough stretching
N-S about the length and width of Britain, placed just down the W
Irish coast.

On the surface at 00Z, the charts show a medium sized depression just
to the W amd NW of Scotland with a trough southwards to the SW of
Ireland. Winds over the whole country are generally from the S. South
of Ireland - and to the SW of England - a secondary depression is
expected to move ENE, across England, and into the North Sea to be near
Holland on 21st November 2003 at 00Z.

According to the charts, I can be sure that a secondary depression.will
be present on or near the position indicated. What is difficult to
forecast, is the strength of the wind. Among other things, the
variation in actual temperature can alter the central pressure of the
secondary depression. The charts do suggest that the stronger winds
should be found over SW England rather than SE England., and that the
secondary depression should fill more and more as it moves into the
North Sea.

Following the depression across the country means forecasting at short
intervals. Usually 3 hour intervals don't show much change - especially
when forecasts such as these are already working at "noise level". But
it is just possible to pick out the position of the depression and this
I have done where some clarity has been evident..

At 0600Z, rain showers should cover N, NW and W Scotland. There is
the possibility of a thin belt of fine weather stretching from Ireland
to NE England. Further south, rain associated with the secondary
depression near S Wales and SW England should move towards the SE of
England. These condition described here are only valid for the time
0600Z. An hour later, features (such as the fine weather in the north)
could, accoring to past experience, change rapidly.

At 1200Z, the secondary depression should form a complex LP system from
S Wales (or thereabouts) to N Scotland. Strong winds should become
evident over S Ireland and SW and S England. How strong, I don't know.
Rainy weather can be expected over Scotland and the W of Britain.
Weather deteriorates from the W over E England.

At 1500Z, the secondary can be identified over the central part of S
England and the central Midlands. Rain showers can be found over most
of the country, but rising pressure and improving weather can be found
over S Ireland.

At 1800Z, the secondary should be approaching E Anglia with winds
turning WSW or W over S England. Heavy rain is possible over Scotland
and N Ireland. The best weather is over SW England.

At 2100 Z, high pressure pushes into the SW of England and pressure
rises generally over the whole country except the extreme W of
Scotland. The secondary should be in the North Sea on its way to
Holland and S Denmark. Fine, clear weather comes into the whole country
from the SW.

The descriptions I have given you are exactly what the charts show. I
know that if I add my own embellishments, the forecast would certainly
come off course. It is only by following the method implicitly that I
can hope the forecast will have some success.

Let's wait till 20th November 2003

Cheers, Keith.

20th November 2003 - special forecast
 

There are good theoretical reasons for saying that a 20-day forecast of
the positions of synoptic-scale systems is intrinsically impossible, regardless
of the accuracy of the initial observations and the degree of perfection of the
computer model. This is due to the way in which energy is transferred from the
sub-micro scale (inches or less) to the synoptic scale in the atmosphere. In
other words, chaos. Also, more pragmatically, no-one has ever achieved success
on the synoptic scale at this range, even if long-term forecasts of monthly
averages are occasionally useful. So why should anyone take you seriously?

Tudor Hughes, Warlingham, Surrey.

20th November 2003 - special forecast
 

Hello, WeatherCam!

'How in the hell can I forecast for 20th November?' Well, I don't use the
forecasting methods which everyone else seems to use. I use a DIRECT method
and not a SUCCESSIVE method of forecasting. I need a date and a time and the
forecast is ready. I have one shot only and that is usually sufficient to
describe the event.

The forecast I made for 20th is intended as an early warning of what is likely
to happen. It would be better for you to check this with the official
forecasts a few days previously before taking any hurried action.

That being said, it doesn't take me off the hook. I made the forecast and I
stand by what I have said. But when all has been said and done, the forecast
is still experimental and should be seen in that light.

Cheers, Keith



WeatherCam schrieb:

Sorry if I'm making a "faux pas" here in newsgroup etiqutte - but how the
hell can you forecast for 20th Nov - as an avid wind watcher for my sport
we're at odds with all the recent blocking of high pressure systems and the
in-accurate forecasting of wind over the past three months - only now, one
day in advance can we be reasonably confident that yet again we will not be
let down by the promise of strong winds and that a rogue high pressure
system will not get in the way of approaching wind....that is from the
SW.....for kite / wind surfers we're amazed at just how bad 5 day forecasts
have been of late!!

REgards
WC

"Keith Darlington" wrote in message
...
What's so special about a forecast?
- it's probably the only forecast of its kind, .
- it's a T+24 DAY forecast
- it's a special weather situation with potentially interesting
developement
- it's experimental and describes the weather variations down to 3
hours.

While completing the series of forecast charts for T+10 day to T+20
days, I came across the chart for 20th November 2003, which attracted
my attention straight away. because of a secondary depression coming
into the country from the SW which had every possibility of bringing
strong winds along with it.

The next step was to check the forecast 500mb-top to see what effect
the surface situation would have in the upper atmosphere. On the day
in question, the 00Z chart showed an upper-air, narrow trough stretching
N-S about the length and width of Britain, placed just down the W
Irish coast.

On the surface at 00Z, the charts show a medium sized depression just
to the W amd NW of Scotland with a trough southwards to the SW of
Ireland. Winds over the whole country are generally from the S. South
of Ireland - and to the SW of England - a secondary depression is
expected to move ENE, across England, and into the North Sea to be near
Holland on 21st November 2003 at 00Z.

According to the charts, I can be sure that a secondary depression.will
be present on or near the position indicated. What is difficult to
forecast, is the strength of the wind. Among other things, the
variation in actual temperature can alter the central pressure of the
secondary depression. The charts do suggest that the stronger winds
should be found over SW England rather than SE England., and that the
secondary depression should fill more and more as it moves into the
North Sea.

Following the depression across the country means forecasting at short
intervals. Usually 3 hour intervals don't show much change - especially
when forecasts such as these are already working at "noise level". But
it is just possible to pick out the position of the depression and this
I have done where some clarity has been evident..

At 0600Z, rain showers should cover N, NW and W Scotland. There is
the possibility of a thin belt of fine weather stretching from Ireland
to NE England. Further south, rain associated with the secondary
depression near S Wales and SW England should move towards the SE of
England. These condition described here are only valid for the time
0600Z. An hour later, features (such as the fine weather in the north)
could, accoring to past experience, change rapidly.

At 1200Z, the secondary depression should form a complex LP system from
S Wales (or thereabouts) to N Scotland. Strong winds should become
evident over S Ireland and SW and S England. How strong, I don't know.
Rainy weather can be expected over Scotland and the W of Britain.
Weather deteriorates from the W over E England.

At 1500Z, the secondary can be identified over the central part of S
England and the central Midlands. Rain showers can be found over most
of the country, but rising pressure and improving weather can be found
over S Ireland.

At 1800Z, the secondary should be approaching E Anglia with winds
turning WSW or W over S England. Heavy rain is possible over Scotland
and N Ireland. The best weather is over SW England.

At 2100 Z, high pressure pushes into the SW of England and pressure
rises generally over the whole country except the extreme W of
Scotland. The secondary should be in the North Sea on its way to
Holland and S Denmark. Fine, clear weather comes into the whole country
from the SW.

The descriptions I have given you are exactly what the charts show. I
know that if I add my own embellishments, the forecast would certainly
come off course. It is only by following the method implicitly that I
can hope the forecast will have some success.

Let's wait till 20th November 2003

Cheers, Keith.

20th November 2003 - special forecast
 

Hello, Tudor!

You are 100% correct from a computer-model point of view. If I used the same or
a similar method to forecast, I would fully agree with you.

But there are other methods of forecasting the weather which give better, and more
reliable results over a longer period of time. In my own method there is no chaos,
no butterflies, no 4 to 5 day limit of success, no ten or more shots at a
forecast until it's correct. In my own case, weather is organized and on time -
and this fact allows me to make forecasts for any time in the future and in the
past.

You should however, form your own opinion, and I advise you to check the
forecasts for yourself against actual conditions (not against another forecast -
it's a waste of time that way) Perhaps we could talk again at a later time.

Cheers, Keith

TudorHgh schrieb:

There are good theoretical reasons for saying that a 20-day forecast of
the positions of synoptic-scale systems is intrinsically impossible, regardless
of the accuracy of the initial observations and the degree of perfection of the
computer model. This is due to the way in which energy is transferred from the
sub-micro scale (inches or less) to the synoptic scale in the atmosphere. In
other words, chaos. Also, more pragmatically, no-one has ever achieved success
on the synoptic scale at this range, even if long-term forecasts of monthly
averages are occasionally useful. So why should anyone take you seriously?

Tudor Hughes, Warlingham, Surrey.

20th November 2003 - special forecast
 

Yn erthygl , sgrifennodd
Keith Darlington :
Hello, WeatherCam!

'How in the hell can I forecast for 20th November?' Well, I don't use the
forecasting methods which everyone else seems to use. I use a DIRECT method
and not a SUCCESSIVE method of forecasting. I need a date and a time and the
forecast is ready. I have one shot only and that is usually sufficient to
describe the event.

I don't really understand this. It implies that no matter what happens
between now and 20th November (or whenever) it is irrelevant to your forecast,
and that should something unexpected happen during that time, your forecast
will still be valid.

That doesn't make sense to me.

Adrian
--
Adrian Shaw ais@
Adran Cyfrifiadureg, Prifysgol Cymru, aber.
Aberystwyth, Ceredigion, Cymru ac.
http://users.aber.ac.uk/ais uk

20th November 2003 - special forecast
 

Hello Adrian!

What you say is true. It does'nt matter what happens in the meantime it won't
affect the forecast on the future date. There is no consecutiveness in actual
weather. What happened yesterday is not valid for today's weather. It is
important for computer forecasting to know what happened yesterday because they
need to know. That's why I only have one shot at a forecast. If I made the
forecast last year for next week's weather, it would still be exactly the same
forecast without the slightest change.

Computer forecasting takes advantage of the fact that there is a short time flow in
weather (SOMETIMES). That means - if a depression is moving NE'wards yesterday,
the chances are that it will move NE today (as a rough example) Its direction
and position can be calculate and then shown on the next forecast chart. But if
nature decides otherwise, the forecast is wrong.

My own position is more on the side of nature and natural weather than on the
computer side of forecasting.

Cheers, Keith.

"Adrian D. Shaw" schrieb:

Yn erthygl , sgrifennodd
Keith Darlington :
Hello, WeatherCam!

'How in the hell can I forecast for 20th November?' Well, I don't use the
forecasting methods which everyone else seems to use. I use a DIRECT method
and not a SUCCESSIVE method of forecasting. I need a date and a time and the
forecast is ready. I have one shot only and that is usually sufficient to
describe the event.

I don't really understand this. It implies that no matter what happens
between now and 20th November (or whenever) it is irrelevant to your forecast,
and that should something unexpected happen during that time, your forecast
will still be valid.

That doesn't make sense to me.

Adrian
--
Adrian Shaw ais@
Adran Cyfrifiadureg, Prifysgol Cymru, aber.
Aberystwyth, Ceredigion, Cymru ac.
http://users.aber.ac.uk/ais uk