On Apr 9, 11:55*am, Bridge of Sighs wrote:
On Apr 9, 9:40*am, Dawlish wrote:





On Apr 9, 9:31*am, Dawlish wrote:

On Apr 8, 1:14*pm, Dawlish wrote:

Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

The gfs develops the North African plume further this morning, with
some pretty scorching spring weather over Spain (El Horno could be
fired up early!) on the 18th but this run terminates the Northerly
extent of its influence in the Gironde and leaves us in cool North-
Westerlies. That could change over the next couple of days, but if
this forecast joins the 20-25% of complete and utter faliiures - oh
well! So be it! It happens. It's still a lot of fun trying. My
forecast of a Northerly plunge and a cold Easter in 2007 wasn't the
best *)) , but there have been 42 successes over the last couple of
years! Plumes seem to be very hard to correctly forecast at 10 days.
They require such specific synoptics to reach the UK. The gfs is still
wrestling with the position of that Atlantic Low sitting off Iberia on
the 00z.

http://www.wetterzentrale.de/pics/Rtavn2282.png

This run puts it further South than it was when I made the forecast
yesterday. For the plume to reach the UK, it needs to be several
hundred miles further North. It'll be interesting watching it.

Paul- Hide quoted text -

- Show quoted text -

Further out, another thing I'm watching is a possible cooler plunge,
with High pressure to our west and low pressure to the East, which
would lead to .......you guessed it! Another bout of cool, showery
Northerlies to end April. Just what we need to cheer us up in mid-
spring! If the plume doesn't get to us, April may is likely to end up
with a colder CET than average.

Presently: * CET: (Apr 1- 8): 7.4°C (-0.1 degC)
(C/O climate-uk.com Thanks Philip)

Paul- Hide quoted text -

- Show quoted text -

Seems reasonable. I've gone for a cooler than average April to follow
the "technically" correct wet,windy and cool March although in many
ways it wasn't that far from average. Theres little zonal movement
currently and unfortunately we are not yet able to tap into the very
warm air that keeps drifting into S Europe. This will be more likely
in May.- Hide quoted text -

- Show quoted text -

Hi,

I've not a believer that anything is forecastable a month in advance,
but I would accept that unless this plume reaches our shores, it is
more likely that May will see warmer weather, than will late April;
though the far reaches of the run show warmer than of late!

The gfs is still playing with that warm, North African air on the 06z.

Paul

Dawlish wrote:
Darren's right in his analysis. Warming slowly this week to close to
average April temps over the weekend, but the T+240 gfs charts have
been changing over the last couple of days and that change has now
come into a time scale of a week away.

All change now:
http://earthquake.usgs.gov/eqcenter/...quakes_big.php

On Apr 9, 7:56 pm, Weatherlawyer wrote:
Dawlish wrote:

Darren's right in his analysis. Warming slowly this week to close to
average April temps over the weekend, but the T+240 gfs charts have
been changing over the last couple of days and that change has now
come into a time scale of a week away.

All change now:
http://earthquake.usgs.gov/eqcenter/...quakes_big.php

Oddly things don't appear to have changed at all. In fact things seem
to have heightened/worsened.

An high pressure system that extended from the North Atlantic to the
North Pole is now extended right through into Asia covering some 90
degrees.

http://www.weatheroffice.gc.ca/data/analysis/947_50.gif

The cyclogenesis that has been running in waves across the USA over
the last few week has stalled over the central southern states:

http://weather.unisys.com/images/sat_sfc_map_loop.html

Texas and Arkansas has copped for quite a bowlful:

http://www.spc.noaa.gov/climo/reports/yesterday.html

On Apr 9, 12:27*pm, Dawlish wrote:
On Apr 9, 11:55*am, Bridge of Sighs wrote:





On Apr 9, 9:40*am, Dawlish wrote:

On Apr 9, 9:31*am, Dawlish wrote:

On Apr 8, 1:14*pm, Dawlish wrote:

Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

The gfs develops the North African plume further this morning, with
some pretty scorching spring weather over Spain (El Horno could be
fired up early!) on the 18th but this run terminates the Northerly
extent of its influence in the Gironde and leaves us in cool North-
Westerlies. That could change over the next couple of days, but if
this forecast joins the 20-25% of complete and utter faliiures - oh
well! So be it! It happens. It's still a lot of fun trying. My
forecast of a Northerly plunge and a cold Easter in 2007 wasn't the
best *)) , but there have been 42 successes over the last couple of
years! Plumes seem to be very hard to correctly forecast at 10 days.
They require such specific synoptics to reach the UK. The gfs is still
wrestling with the position of that Atlantic Low sitting off Iberia on
the 00z.

http://www.wetterzentrale.de/pics/Rtavn2282.png

This run puts it further South than it was when I made the forecast
yesterday. For the plume to reach the UK, it needs to be several
hundred miles further North. It'll be interesting watching it.

Paul- Hide quoted text -

- Show quoted text -

Further out, another thing I'm watching is a possible cooler plunge,
with High pressure to our west and low pressure to the East, which
would lead to .......you guessed it! Another bout of cool, showery
Northerlies to end April. Just what we need to cheer us up in mid-
spring! If the plume doesn't get to us, April may is likely to end up
with a colder CET than average.

Presently: * CET: (Apr 1- 8): 7.4°C (-0.1 degC)
(C/O climate-uk.com Thanks Philip)

Paul- Hide quoted text -

- Show quoted text -

Seems reasonable. I've gone for a cooler than average April to follow
the "technically" correct wet,windy and cool March although in many
ways it wasn't that far from average. Theres little zonal movement
currently and unfortunately we are not yet able to tap into the very
warm air that keeps drifting into S Europe. This will be more likely
in May.- Hide quoted text -

- Show quoted text -

Hi,

I've not a believer that anything is forecastable a month in advance,
but I would accept that unless this plume reaches our shores, it is
more likely that May will see warmer weather, than will late April;
though the far reaches of the run show warmer than of late!

The gfs is still playing with that warm, North African air on the 06z.

Paul- Hide quoted text -

- Show quoted text -

Not looking one of the best forecasts I've ever produced, this
morning, but judge it at outcome, as we should all forecasts. I will!

Paul

On Apr 10, 9:39*am, Dawlish wrote:
On Apr 9, 12:27*pm, Dawlish wrote:





On Apr 9, 11:55*am, Bridge of Sighs wrote:

On Apr 9, 9:40*am, Dawlish wrote:

On Apr 9, 9:31*am, Dawlish wrote:

On Apr 8, 1:14*pm, Dawlish wrote:

Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

The gfs develops the North African plume further this morning, with
some pretty scorching spring weather over Spain (El Horno could be
fired up early!) on the 18th but this run terminates the Northerly
extent of its influence in the Gironde and leaves us in cool North-
Westerlies. That could change over the next couple of days, but if
this forecast joins the 20-25% of complete and utter faliiures - oh
well! So be it! It happens. It's still a lot of fun trying. My
forecast of a Northerly plunge and a cold Easter in 2007 wasn't the
best *)) , but there have been 42 successes over the last couple of
years! Plumes seem to be very hard to correctly forecast at 10 days.
They require such specific synoptics to reach the UK. The gfs is still
wrestling with the position of that Atlantic Low sitting off Iberia on
the 00z.

http://www.wetterzentrale.de/pics/Rtavn2282.png

This run puts it further South than it was when I made the forecast
yesterday. For the plume to reach the UK, it needs to be several
hundred miles further North. It'll be interesting watching it.

Paul- Hide quoted text -

- Show quoted text -

Further out, another thing I'm watching is a possible cooler plunge,
with High pressure to our west and low pressure to the East, which
would lead to .......you guessed it! Another bout of cool, showery
Northerlies to end April. Just what we need to cheer us up in mid-
spring! If the plume doesn't get to us, April may is likely to end up
with a colder CET than average.

Presently: * CET: (Apr 1- 8): 7.4°C (-0.1 degC)
(C/O climate-uk.com Thanks Philip)

Paul- Hide quoted text -

- Show quoted text -

Seems reasonable. I've gone for a cooler than average April to follow
the "technically" correct wet,windy and cool March although in many
ways it wasn't that far from average. Theres little zonal movement
currently and unfortunately we are not yet able to tap into the very
warm air that keeps drifting into S Europe. This will be more likely
in May.- Hide quoted text -

- Show quoted text -

Hi,

I've not a believer that anything is forecastable a month in advance,
but I would accept that unless this plume reaches our shores, it is
more likely that May will see warmer weather, than will late April;
though the far reaches of the run show warmer than of late!

The gfs is still playing with that warm, North African air on the 06z.

Paul- Hide quoted text -

- Show quoted text -

Not looking one of the best forecasts I've ever produced, this
morning, but judge it at outcome, as we should all forecasts. I will!

Paul- Hide quoted text -

- Show quoted text -

Back to my forecast for the 18th being largely correct. The gfs is
again showing Southerlies on the 18th, but perhaps not quite as warm
as I've forecast.

http://www.wetterzentrale.de/pics/Rtavn1682.png

It's that model development of a particular event, seeming
abandonment, then reappearance of that event which first interested me
in the possibilities of forecasting at 10 days+. Time delayed
coincidence. What are the chances of that happening, through simple
inputs of changing data? These are simply numbers remember. 5
consecutive runs showing a particular synoptic situation, then a
fairly radical change away from it, for several runs, then a
reappearance of the same phenomenen that then (hopefully) sticks.

If Southern England gets Southerly winds on the 18th, somewhere is
likely to achieve the 18C that I predicted. However, there's still a
week for this to go down the pan.........! It really does depend on
the exact position of that Atlantic low and it's counterpart, the old
"Scandi high" (so often quoted as a friendly chappie, with its cold
winter buddy, the Greenie high!) . With the low a little further South
than present and more warmer air being dragged Northwards, 18C could
be widespread at the start of next week. Then again, if the high
declines and that low makes progress Eastwards, Atlantic mP air
spreads across the UK and the forecast is down. If the high spreads
its influence Westwards, we end up in Easterlies, the holy grail of
winter, and again, the forecast is down.

After the reappearance of those Southerlies, I'm reasonably confident
they'll be there in a week's time, but "reasonably confident" marks
that as about 80%. As the Alcoholic always knows, it's just the last
fifth that kills you - the rest of the bottles were no problem!

Paul

Paul

On Apr 11, 9:28*am, Dawlish wrote:
On Apr 10, 9:39*am, Dawlish wrote:





On Apr 9, 12:27*pm, Dawlish wrote:

On Apr 9, 11:55*am, Bridge of Sighs wrote:

On Apr 9, 9:40*am, Dawlish wrote:

On Apr 9, 9:31*am, Dawlish wrote:

On Apr 8, 1:14*pm, Dawlish wrote:

Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

The gfs develops the North African plume further this morning, with
some pretty scorching spring weather over Spain (El Horno could be
fired up early!) on the 18th but this run terminates the Northerly
extent of its influence in the Gironde and leaves us in cool North-
Westerlies. That could change over the next couple of days, but if
this forecast joins the 20-25% of complete and utter faliiures - oh
well! So be it! It happens. It's still a lot of fun trying. My
forecast of a Northerly plunge and a cold Easter in 2007 wasn't the
best *)) , but there have been 42 successes over the last couple of
years! Plumes seem to be very hard to correctly forecast at 10 days.
They require such specific synoptics to reach the UK. The gfs is still
wrestling with the position of that Atlantic Low sitting off Iberia on
the 00z.

http://www.wetterzentrale.de/pics/Rtavn2282.png

This run puts it further South than it was when I made the forecast
yesterday. For the plume to reach the UK, it needs to be several
hundred miles further North. It'll be interesting watching it.

Paul- Hide quoted text -

- Show quoted text -

Further out, another thing I'm watching is a possible cooler plunge,
with High pressure to our west and low pressure to the East, which
would lead to .......you guessed it! Another bout of cool, showery
Northerlies to end April. Just what we need to cheer us up in mid-
spring! If the plume doesn't get to us, April may is likely to end up
with a colder CET than average.

Presently: * CET: (Apr 1- 8): 7.4°C (-0.1 degC)
(C/O climate-uk.com Thanks Philip)

Paul- Hide quoted text -

- Show quoted text -

Seems reasonable. I've gone for a cooler than average April to follow
the "technically" correct wet,windy and cool March although in many
ways it wasn't that far from average. Theres little zonal movement
currently and unfortunately we are not yet able to tap into the very
warm air that keeps drifting into S Europe. This will be more likely
in May.- Hide quoted text -

- Show quoted text -

Hi,

I've not a believer that anything is forecastable a month in advance,
but I would accept that unless this plume reaches our shores, it is
more likely that May will see warmer weather, than will late April;
though the far reaches of the run show warmer than of late!

The gfs is still playing with that warm, North African air on the 06z.

Paul- Hide quoted text -

- Show quoted text -

Not looking one of the best forecasts I've ever produced, this
morning, but judge it at outcome, as we should all forecasts. I will!

Paul- Hide quoted text -

- Show quoted text -

Back to my forecast for the 18th being largely correct. The gfs is
again showing Southerlies on the 18th, but perhaps not quite as warm
as I've forecast.

http://www.wetterzentrale.de/pics/Rtavn1682.png

It's that model development of a particular event, seeming
abandonment, then reappearance of that event which first interested me
in the possibilities of forecasting at 10 days+. Time delayed
coincidence. What are the chances of that happening, through simple
inputs of changing data? These are simply numbers remember. 5
consecutive runs showing a particular synoptic situation, then a
fairly radical change away from it, for several runs, then a
reappearance of the same phenomenen that then (hopefully) sticks.

If Southern England gets Southerly winds on the 18th, somewhere is
likely to achieve the 18C that I predicted. However, there's still a
week for this to go down the pan.........! It really does depend on
the exact position of that Atlantic low and it's counterpart, the old
"Scandi high" (so often quoted as a friendly chappie, with its cold
winter buddy, the Greenie high!) . With the low a little further South
than present and more warmer air being dragged Northwards, 18C could
be widespread at the start of next week. Then again, if the high
declines and that low makes progress Eastwards, Atlantic mP air
spreads across the UK and the forecast is down. If the high spreads
its influence Westwards, we end up in Easterlies, the holy grail of
winter, and again, the forecast is down.

After the reappearance of those Southerlies, I'm reasonably confident
they'll be there in a week's time, but "reasonably confident" marks
that as about 80%. As the Alcoholic always knows, it's just the last
fifth that kills you - the rest of the bottles were no problem!

Paul

Paul- Hide quoted text -

- Show quoted text -

Not looking good for this forecast now. It is more likely that the
winds will swing SE, then East towards the end of this week, with a
low over Northern France cutting off any hopes of warmth from the
South approaching us.

There's always something to look at T240+ though. The cold Northerly
plunge, that I remarked on a few days ago never developed and never
stayed long enough for a forecast, but the gfs is keen to sink that
low SE and allow high pressure to build SE over us and that may be
worth a T240 forecast, should that development stay on the charts
until tomorrow morning. It would bring much more settled conditions,
but, should it develop, we are not looking at warmth. This would be a
far cry from a warm Azores high. This high would have developed over
the cold North Atlantic and it could lead to some pretty cool and
cloudy weather if moisture became trapped in a temperature inversion
as it tracked SE. My confidence is not high enough for an actual
forecast yet.

Paul

On Apr 13, 9:14*am, Dawlish wrote:
On Apr 11, 9:28*am, Dawlish wrote:





On Apr 10, 9:39*am, Dawlish wrote:

On Apr 9, 12:27*pm, Dawlish wrote:

On Apr 9, 11:55*am, Bridge of Sighs wrote:

On Apr 9, 9:40*am, Dawlish wrote:

On Apr 9, 9:31*am, Dawlish wrote:

On Apr 8, 1:14*pm, Dawlish wrote:

Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

The gfs develops the North African plume further this morning, with
some pretty scorching spring weather over Spain (El Horno could be
fired up early!) on the 18th but this run terminates the Northerly
extent of its influence in the Gironde and leaves us in cool North-
Westerlies. That could change over the next couple of days, but if
this forecast joins the 20-25% of complete and utter faliiures - oh
well! So be it! It happens. It's still a lot of fun trying. My
forecast of a Northerly plunge and a cold Easter in 2007 wasn't the
best *)) , but there have been 42 successes over the last couple of
years! Plumes seem to be very hard to correctly forecast at 10 days.
They require such specific synoptics to reach the UK. The gfs is still
wrestling with the position of that Atlantic Low sitting off Iberia on
the 00z.

http://www.wetterzentrale.de/pics/Rtavn2282.png

This run puts it further South than it was when I made the forecast
yesterday. For the plume to reach the UK, it needs to be several
hundred miles further North. It'll be interesting watching it.

Paul- Hide quoted text -

- Show quoted text -

Further out, another thing I'm watching is a possible cooler plunge,
with High pressure to our west and low pressure to the East, which
would lead to .......you guessed it! Another bout of cool, showery
Northerlies to end April. Just what we need to cheer us up in mid-
spring! If the plume doesn't get to us, April may is likely to end up
with a colder CET than average.

Presently: * CET: (Apr 1- 8): 7.4°C (-0.1 degC)
(C/O climate-uk.com Thanks Philip)

Paul- Hide quoted text -

- Show quoted text -

Seems reasonable. I've gone for a cooler than average April to follow
the "technically" correct wet,windy and cool March although in many
ways it wasn't that far from average. Theres little zonal movement
currently and unfortunately we are not yet able to tap into the very
warm air that keeps drifting into S Europe. This will be more likely
in May.- Hide quoted text -

- Show quoted text -

Hi,

I've not a believer that anything is forecastable a month in advance,
but I would accept that unless this plume reaches our shores, it is
more likely that May will see warmer weather, than will late April;
though the far reaches of the run show warmer than of late!

The gfs is still playing with that warm, North African air on the 06z.

Paul- Hide quoted text -

- Show quoted text -

Not looking one of the best forecasts I've ever produced, this
morning, but judge it at outcome, as we should all forecasts. I will!

Paul- Hide quoted text -

- Show quoted text -

Back to my forecast for the 18th being largely correct. The gfs is
again showing Southerlies on the 18th, but perhaps not quite as warm
as I've forecast.

http://www.wetterzentrale.de/pics/Rtavn1682.png

It's that model development of a particular event, seeming
abandonment, then reappearance of that event which first interested me
in the possibilities of forecasting at 10 days+. Time delayed
coincidence. What are the chances of that happening, through simple
inputs of changing data? These are simply numbers remember. 5
consecutive runs showing a particular synoptic situation, then a
fairly radical change away from it, for several runs, then a
reappearance of the same phenomenen that then (hopefully) sticks.

If Southern England gets Southerly winds on the 18th, somewhere is
likely to achieve the 18C that I predicted. However, there's still a
week for this to go down the pan.........! It really does depend on
the exact position of that Atlantic low and it's counterpart, the old
"Scandi high" (so often quoted as a friendly chappie, with its cold
winter buddy, the Greenie high!) . With the low a little further South
than present and more warmer air being dragged Northwards, 18C could
be widespread at the start of next week. Then again, if the high
declines and that low makes progress Eastwards, Atlantic mP air
spreads across the UK and the forecast is down. If the high spreads
its influence Westwards, we end up in Easterlies, the holy grail of
winter, and again, the forecast is down.

After the reappearance of those Southerlies, I'm reasonably confident
they'll be there in a week's time, but "reasonably confident" marks
that as about 80%. As the Alcoholic always knows, it's just the last
fifth that kills you - the rest of the bottles were no problem!

Paul

Paul- Hide quoted text -

- Show quoted text -

Not looking good for this forecast now. It is more likely that the
winds will swing SE, then East towards the end of this week, with a
low over Northern France cutting off any hopes of warmth from the
South approaching us.

There's always something to look at T240+ though. The cold Northerly
plunge, that I remarked on a few days ago never developed and never
stayed long enough for a forecast, but the gfs is keen to sink that
low SE and allow high pressure to build SE over us and that may be
worth a T240 forecast, should that development stay on the charts
until tomorrow morning. It would bring much more settled conditions,
but, should it develop, we are not looking at warmth. This would be a
far cry from a warm Azores high. This high would have developed over
the cold North Atlantic and it could lead to some pretty cool and
cloudy weather if moisture became trapped in a temperature inversion
as it tracked SE. My confidence is not high enough for an actual
forecast yet.

Paul- Hide quoted text -

- Show quoted text -

No UK hIgh pressure forecast at 10 days from this changing output. The
blocking stays firmly to our North, out to T240 and is not now being
shown to settle over us. Something perhaps interesting at T300. Some
late April warmth has been there for two runs and has caught my
attention, but no more.

Paul

On Apr 14, 12:56*pm, Dawlish wrote:
On Apr 13, 9:14*am, Dawlish wrote:





On Apr 11, 9:28*am, Dawlish wrote:

On Apr 10, 9:39*am, Dawlish wrote:

On Apr 9, 12:27*pm, Dawlish wrote:

On Apr 9, 11:55*am, Bridge of Sighs wrote:

On Apr 9, 9:40*am, Dawlish wrote:

On Apr 9, 9:31*am, Dawlish wrote:

On Apr 8, 1:14*pm, Dawlish wrote:

Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

The gfs develops the North African plume further this morning, with
some pretty scorching spring weather over Spain (El Horno could be
fired up early!) on the 18th but this run terminates the Northerly
extent of its influence in the Gironde and leaves us in cool North-
Westerlies. That could change over the next couple of days, but if
this forecast joins the 20-25% of complete and utter faliiures - oh
well! So be it! It happens. It's still a lot of fun trying. My
forecast of a Northerly plunge and a cold Easter in 2007 wasn't the
best *)) , but there have been 42 successes over the last couple of
years! Plumes seem to be very hard to correctly forecast at 10 days.
They require such specific synoptics to reach the UK. The gfs is still
wrestling with the position of that Atlantic Low sitting off Iberia on
the 00z.

http://www.wetterzentrale.de/pics/Rtavn2282.png

This run puts it further South than it was when I made the forecast
yesterday. For the plume to reach the UK, it needs to be several
hundred miles further North. It'll be interesting watching it.

On Apr 8, 1:14*pm, Dawlish wrote:
Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

I always return to any forecast I make, be it good, or bad!

OK a hopeless forecast. This one fell into the 20-25% of faliures and
it ranks as a stinker amongst those (Euro stinker? No muck on the
ground in the rain though in Devon!) . It's not even a near miss and
it ranks on the abysmal level of the Cold Northerly I forecast at
Easter 2007 (remember that glorious, warm sunny weather at an Easter
which now sits in the warmest April for 350+ years?)

The reason was a combination of a Southerly diving jet, producing cold
uppers and an associated lee depression which is likely to track W to
E along the channel and across Northern France. It has stymied any
development of that warm plume that was shown on the gfs for a few
days, in one form or another, 10 days ago. This was compounded by*
the Northern blocking of Early April continuing and sitting there over
Iceland, like a giant high pressure toad, squatting with its heavy
haunches and putting up an impenetrable wall of toady atmosphere
against the release of my predicted North African plume. OK,
stretching a metaphor, but I hope you get the picture.

Maybe I've got the first plume right, at 10 days, on the max temp
record thread!

Paul

* Does high pressure at our latitudes result from the track of the
jet, or does it alter the jet's path. Has this jet been forced South
by an anticyclone which stretches from ground level to the 200mb hpa
level, or did it form as a result of the jet tracking south? It's a
chicken and egg scenario that I've always found hard to interpret. In
this case, I'd go with the high developing and the jet being forced
around it, but I could be wrong! Any clues, anyone?

"Dawlish" wrote in message
...
On Apr 8, 1:14 pm, Dawlish wrote:
Well, there you go.The possible warmth has continued for 5 runs, I can
now be 75-80% certain of this:

By 18th April at T240, the effects of the first warm plume of the year
will be being felt in Southern England. Temperatures on the 17th and
18th of April will peak above 18C and may well be higher. Winds around
this time will be from a Southerly quadrant and the air will have had
its source in North Africa. This air could well be unstable enough to
bring the possibility of heavy, perhaps thundery showers. If the
showers stay away, Southern England, at least, will have some
pleasant, warm conditions for April.

It can never be a higher confidence forecast than 75-80%, as my
success from the past is about 78%. It's not a certain forecast, as
certainty doesn't come in to forecasting. See how it goes.

Paul

I always return to any forecast I make, be it good, or bad!

OK a hopeless forecast. This one fell into the 20-25% of faliures and
it ranks as a stinker amongst those (Euro stinker? No muck on the
ground in the rain though in Devon!) . It's not even a near miss and
it ranks on the abysmal level of the Cold Northerly I forecast at
Easter 2007 (remember that glorious, warm sunny weather at an Easter
which now sits in the warmest April for 350+ years?)

The reason was a combination of a Southerly diving jet, producing cold
uppers and an associated lee depression which is likely to track W to
E along the channel and across Northern France. It has stymied any
development of that warm plume that was shown on the gfs for a few
days, in one form or another, 10 days ago. This was compounded by*
the Northern blocking of Early April continuing and sitting there over
Iceland, like a giant high pressure toad, squatting with its heavy
haunches and putting up an impenetrable wall of toady atmosphere
against the release of my predicted North African plume. OK,
stretching a metaphor, but I hope you get the picture.

Maybe I've got the first plume right, at 10 days, on the max temp
record thread!

Paul

* Does high pressure at our latitudes result from the track of the
jet, or does it alter the jet's path. Has this jet been forced South
by an anticyclone which stretches from ground level to the 200mb hpa
level, or did it form as a result of the jet tracking south? It's a
chicken and egg scenario that I've always found hard to interpret. In
this case, I'd go with the high developing and the jet being forced
around it, but I could be wrong! Any clues, anyone?

=====
NEW POST

I cannot quote your previous text as Outlook Express does not recognise the
format you used.

It is the jet, itself arising from temperature variations, that forms the
high pressure regions in our latitudes. Don't foget the global circulation
Hadley cells that help form the various jets in the first place, which
themselves arise from insolation and the earth's rotation. And then there
are the Rossby waves affected by major mountain structures like the Rockies
which meander around and alter the jet streams. The atmosphere should always
be thought of as a system as per Systems Theory. Isolating various parts is
good for understanding physics etc and causes of weather such as rain,
thunder etc, but you need to treat it as a whole to get rid of chickens and
eggs.

Re your forecast. I too was interested in that southerly at T+240. I was
tempted to say something but my instincts (backed up by ensembles) told me
to keep quiet. I've gone for a warm and sunny weekend next weekend instead!
We all make bad forecasts, nobody is perfect, not even WL :-)

No pongs up here, I had a good sniff last night but all I could smell was
wet grass! A bit of a pong yesterday morning as I reported but very very
faint and there a lot of cess pits anyway in these upland parts :-)

Cheers Paul,

Will
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