On Oct 19, 11:28*am, Dawlish wrote:
Looking like this dry spell will end and not return for a while. 4
consecutive gfs runs now showing Atlantic conditions across the UK for
the forseeable future. A large Scandinavian block may delay the
progress of those lows and fronts somewhat, keeping eastern areas of
the UK drier, but that looks as if it may decline and allow in
Atlantic weather further by T240. It would need a 5th gfs run and ECM
agreement for me to forecast with confidence. Not exactly a zonal
train, but not the settled and mainly dry weather that we've become
used to. Never cold, but not particularly mild either. Autumnal
looking, I suppose - whatever exactly that means in the UK!

The possibility of a Scandinavian block that I referred to a couple of
days ago, now seems to be the preferred option at 10 days on the gfs
and ECM and GEM. It isn't being shown to decline, as the models were
suggesting then. Again, to forecast at 10 days with accuracy requires
a combination of agreement and consistency and that didn't happen. A
forecast of Atlantic dominance, back on the 19th, would probably have
proved wrong by the time the 29th came around (i.e. at 10 days).
Instead, after an Atlantic incursion, with some potential gales at the
weekend, that Scandinavian block may become the dominant element in
our weather, holding up the Atlantic, stalling fronts over the east,
keeping the east drier and keeping us all fairly mild at the month's
end. There's good agreement, over the last 18 hours but it'll still
take another couple of gfs runs and agreement with the ECM for me to
be confident that the block will occur.

On Oct 21, 9:36*am, Dawlish wrote:
On Oct 19, 11:28*am, Dawlish wrote:

Looking like this dry spell will end and not return for a while. 4
consecutive gfs runs now showing Atlantic conditions across the UK for
the forseeable future. A large Scandinavian block may delay the
progress of those lows and fronts somewhat, keeping eastern areas of
the UK drier, but that looks as if it may decline and allow in
Atlantic weather further by T240. It would need a 5th gfs run and ECM
agreement for me to forecast with confidence. Not exactly a zonal
train, but not the settled and mainly dry weather that we've become
used to. Never cold, but not particularly mild either. Autumnal
looking, I suppose - whatever exactly that means in the UK!

The possibility of a Scandinavian block that I referred to a couple of
days ago, now seems to be the preferred option at 10 days on the gfs
and ECM and GEM. It isn't being shown to decline, as the models were
suggesting then. Again, to forecast at 10 days with accuracy requires
a combination of agreement and consistency and that didn't happen. A
forecast of Atlantic dominance, back on the 19th, would probably have
proved wrong by the time the 29th came around (i.e. at 10 days).
Instead, after an Atlantic incursion, with some potential gales at the
weekend, that Scandinavian block may become the dominant element in
our weather, holding up the Atlantic, stalling fronts over the east,
keeping the east drier and keeping us all fairly mild at the month's
end. There's good agreement, over the last 18 hours but it'll still
take another couple of gfs runs and agreement with the ECM for me to
be confident that the block will occur.

It's just not there. The 06z sinks the high!

http://www.wetterzentrale.de/pics/Rtavn2402.png

"Dawlish" wrote in message
...


It's just not there. The 06z sinks the high!

http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

On Oct 21, 6:48*pm, "Col" wrote:
"Dawlish" wrote in message

...

It's just not there. The 06z sinks the high!
http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

Very true Col! The 06z was probably an outlier, but the interruption
to the consistency begs a couple more runs and agreement from the ECM
before a forecast.

"Dawlish" wrote in message
...
On Oct 21, 6:48 pm, "Col" wrote:
"Dawlish" wrote in message

...

It's just not there. The 06z sinks the high!
http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

Very true Col! The 06z was probably an outlier, but the interruption
to the consistency begs a couple more runs and agreement from the ECM
before a forecast.

Yes, I am beginning to understand how you approach these10
day forecasts. It's all about consistency and ultimately 'confidence'.
If you get a run that suddenly goes against what the recent runs
have been showing then that confidence is shaken and it takes a
few more runs showing the original sceanario to get that confidence
back to it's original level.
That run *could* be an outlier, but then it *could* depict what the
weather actually does!
--
Col

Bolton, Lancashire
160m asl

"Col" wrote in message
...

"Dawlish" wrote in message
...
On Oct 21, 6:48 pm, "Col" wrote:
"Dawlish" wrote in message

...

It's just not there. The 06z sinks the high!
http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

Very true Col! The 06z was probably an outlier, but the interruption
to the consistency begs a couple more runs and agreement from the ECM
before a forecast.

Yes, I am beginning to understand how you approach these10
day forecasts. It's all about consistency and ultimately 'confidence'.
If you get a run that suddenly goes against what the recent runs
have been showing then that confidence is shaken and it takes a
few more runs showing the original sceanario to get that confidence
back to it's original level.
That run *could* be an outlier, but then it *could* depict what the
weather actually does!
--
Col

Of course professional forecasters don't have that luxury. Customers want
forecasts and they want them now!

Will
--

In article ,
Will Hand writes:

"Col" wrote in message news:4NSdnYGhC8U4zkL
...

"Dawlish" wrote in message

...
On Oct 21, 6:48 pm, "Col" wrote:
"Dawlish" wrote in message

...

It's just not there. The 06z sinks the high!
http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

Very true Col! The 06z was probably an outlier, but the interruption
to the consistency begs a couple more runs and agreement from the ECM
before a forecast.

Yes, I am beginning to understand how you approach these10
day forecasts. It's all about consistency and ultimately 'confidence'.
If you get a run that suddenly goes against what the recent runs
have been showing then that confidence is shaken and it takes a
few more runs showing the original sceanario to get that confidence
back to it's original level.
That run *could* be an outlier, but then it *could* depict what the
weather actually does!
-- Col

Of course professional forecasters don't have that luxury. Customers
want forecasts and they want them now!

But they do have the big advantage of access to the ensembles, whereas I
believe that Dawlish uses only the production runs. Thus he can't tell
whether or not a particular production run is likely to be an outlier
other than by relying on consistency between models and from one run to
the next.
--
John Hall "Do you have cornflakes in America?"
"Well, actually, they're American."
"So what brings you to Britain then if you have cornflakes already?"
Bill Bryson: "Notes from a Small Island"

Will Hand wrote:


Of course professional forecasters don't have that luxury. Customers
want forecasts and they want them now!

Will
--


I'm trying to work out what the weather will be like at Bath next week,
seems to be settling into a high pressure southwesterly now, with a lot
of cloud. here's to hoping for misty starts and sunny afternoons, my
favourite weather in the autumn.

--
Keith (Southend)
http://www.southendweather.net
e-mail: kreh at southendweather dot net

John Hall wrote:

In article ,
Will Hand writes:

"Col" wrote in message news:4NSdnYGhC8U4zkL
...

"Dawlish" wrote in message

...
On Oct 21, 6:48 pm, "Col" wrote:
"Dawlish" wrote in message

...

It's just not there. The 06z sinks the high!
http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

Very true Col! The 06z was probably an outlier, but the interruption
to the consistency begs a couple more runs and agreement from the ECM
before a forecast.

Yes, I am beginning to understand how you approach these10
day forecasts. It's all about consistency and ultimately 'confidence'.
If you get a run that suddenly goes against what the recent runs
have been showing then that confidence is shaken and it takes a
few more runs showing the original sceanario to get that confidence
back to it's original level.
That run could be an outlier, but then it could depict what the
weather actually does!
-- Col

Of course professional forecasters don't have that luxury. Customers
want forecasts and they want them now!

But they do have the big advantage of access to the ensembles, whereas I
believe that Dawlish uses only the production runs. Thus he can't tell
whether or not a particular production run is likely to be an outlier
other than by relying on consistency between models and from one run to
the next.


But why not look at the ensembles? The GFES ensembles are widely promulgated on
the net.


Norman

On Oct 21, 8:30*pm, "Norman" wrote:
John Hall wrote:
In article ,
*Will Hand writes:

"Col" wrote in message news:4NSdnYGhC8U4zkL
...

"Dawlish" wrote in message

...
On Oct 21, 6:48 pm, "Col" wrote:
"Dawlish" wrote in message

...

It's just not there. The 06z sinks the high!
http://www.wetterzentrale.de/pics/Rtavn2402.png

But back again on the 12z.....
--
Col

Bolton, Lancashire
160m asl

Very true Col! The 06z *was probably an outlier, but the interruption
to the consistency begs a couple more runs and agreement from the ECM
before a forecast.

Yes, I am beginning to understand how you approach these10
day forecasts. It's all about consistency and ultimately 'confidence'.
If you get a run that suddenly goes against what the recent runs
have been showing then that confidence is shaken and it takes a
few more runs showing the original sceanario to get that confidence
back to it's original level.
That run could be an outlier, but then it could depict what the
weather actually does!
-- *Col

Of course professional forecasters don't have that luxury. Customers
want forecasts and they want them now!

But they do have the big advantage of access to the ensembles, whereas I
believe that Dawlish uses only the production runs. Thus he can't tell
whether or not a particular production run is likely to be an outlier
other than by relying on consistency between models and from one run to
the next.

But why not look at the ensembles? The GFES ensembles are widely promulgated on
the net.

Norman- Hide quoted text -

- Show quoted text -

Mainly because, at 10 days, ensembles are a waste of time. At that
distance, the error in every run is so great that you can't trust what
you are seeing with the spread. It tends towards randomness. If
ensemble prediction was the answer, we'd have better accuracy at 10
days, but the outcomes show that ensembles are certainly not the
answer. Neither are they "a part of the mix" because the "mix" doesn't
work either. In fact, nothing works at 10 days on a regular basis; if
it did, someone would be able to demonstrate accuracy on a daily basis
and they can't. That is why I only forecast when my technique suggests
I will have at least 75% success and over 74 forecasts, that is the
success rate that I can demonstrate using that method. That has to
count.

I take entirely what Will says about public expectation and he is
completely right. The public expect forecasts every day at 10 days and
more. If it wasn't on the website, there would be complaints galore!
Fortunately, the public don't keep any accuracy records and the MetO
can say just about what they want in the 6-15 day forecasts, with no
comeback whatsoever - everyone has forgotten what they said at
outcome! Well, almost everyone *)). Who tracks the accuracy of that
6-15 day forecast? The MetO don't; NOAA don't and I would suggest that
it is impossible to do that from anyway from the dearth of information
that it contains.

At 10 days we are presently beyond the limits of forecasting with
accuracy on a daily basis. Simple as that.