Posted this in the media thread but maybe more appropriate here.

Even Boris is becoming aware of a change in the air...

http://www.telegraph.co.uk/comment/columnists/borisjohnson/8213058/The-man-who-repeatedly-beats-the-Met-Office-at-its-own-game.html

If only Corbyn was actually right rather than just claiming to be right. He may have been right about recent cold winter weather but IIRC* this is his usual modus operandi - and a stopped clock is still right twice a day

*I can't check because his forecast archive is short and disorganised

As far as I'm aware no-one has attempted a comprehensive independent review of his accuracy but I did bother to look at one month a while ago (think it was Dec 2009) which wasn't very good. Climate scientist James Annan did do it a bit more systematically for a while but I guess he stopped when he felt he'd made his point; he only looked at monthly temp/rainfall forecasts rater than individual events which gives *****more chance to be right.

http://julesandjames.blogspot.com/2009/01/corbynwatch-2008-verdict.html

Have you tried looking at the "Forecast accuracy" on his site ?

www.***********.com

As far as I'm aware no-one has attempted a comprehensive independent review of his accuracy but I did bother to look at one month a while ago (think it was Dec 2009) which wasn't very good.

I've done a few assessments and find that whilst he may sometimes do reasonably well in terms of general trends (ie wet & windy second half of the month), he falls down a lot on specifics and of course he has had a few well documented 'disasters'.

For example, he wonders why the Govt still ignore him - after sending them a warning a catastrophic flooding in August 2007 ......

(and he did forecast that the weekend of the July 2007 floods hit here would be one of the few periods that month which were going to be warm, dry and sunny with no flooding)

When the Nov 2009 floods hit Cumbria he had, to be fair, warned of flooding and a storm surge .... In East Anglia ......

http://weatherearthnews.blogspot.com/2009/11/19th-november-flooding-in-britain.html

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I've found his hindcasts pretty stunning though!

 

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As far as I'm aware no-one has attempted a comprehensive independent review of his accuracy but I did bother to look at one month a while ago (think it was Dec 2009) which wasn't very good.

I've done a few assessments and find that whilst he may sometimes do reasonably well in terms of general trends (ie wet & windy second half of the month), he falls down a lot on specifics and of course he has had a few well documented 'disasters'.

For example, he wonders why the Govt still ignore him - after sending them a warning a catastrophic flooding in August 2007 ......

(and he did forecast that the weekend of the July 2007 floods hit here would be one of the few periods that month which were going to be warm, dry and sunny with no flooding)

When the Nov 2009 floods hit Cumbria he had, to be fair, warned of flooding and a storm surge .... In East Anglia ......

http://weatherearthnews.blogspot.com/2009/11/19th-november-flooding-in-britain.html

The wetest days were the 20th and 23rd July, either side of the weekend, and both within the forecast periods for heavy rain and floods. That weekend was actually the shortest dry period forecast on the whole month`s forecast.

If you want to inspect it, mail me and I will forward it.  [email protected]

 

As far as I'm aware no-one has attempted a comprehensive independent review of his accuracy but I did bother to look at one month a while ago (think it was Dec 2009) which wasn't very good.

I've done a few assessments and find that whilst he may sometimes do reasonably well in terms of general trends (ie wet & windy second half of the month), he falls down a lot on specifics and of course he has had a few well documented 'disasters'.

For example, he wonders why the Govt still ignore him - after sending them a warning a catastrophic flooding in August 2007 ......

(and he did forecast that the weekend of the July 2007 floods hit here would be one of the few periods that month which were going to be warm, dry and sunny with no flooding)

When the Nov 2009 floods hit Cumbria he had, to be fair, warned of flooding and a storm surge .... In East Anglia ......

http://weatherearthnews.blogspot.com/2009/11/19th-november-flooding-in-britain.html

He claims 85% success rate, not 100%. As the weather is mostly quiet or uneventful for much of the time, his successes may go un-noticed for much of the time. The examples n which you pick Andy would have a web presence because of the nature of the event. Maybe that constitutes the 15% errors .

 

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He claims 85% success rate, not 100%. As the weather is mostly quiet or uneventful for much of the time, his successes may go un-noticed for much of the time. The examples n which you pick Andy would have a web presence because of the nature of the event. Maybe that constitutes the 15% errors .

Except the link I provided earlier credits him with much less than a 85% success rate.

It all depends on how he validates his forecasts. He may predict a storm in a 3-day window in October, but the chances of a depression crossing the UK in any 3-day period in October is fairly high. Does it count as a success if he predicts gales and flooding and it's just damp and a bit breezy?

 

He claims 85% success rate, not 100%. As the weather is mostly quiet or uneventful for much of the time, his successes may go un-noticed for much of the time. The examples n which you pick Andy would have a web presence because of the nature of the event. Maybe that constitutes the 15% errors .

Except the link I provided earlier credits him with much less than a 85% success rate.

It all depends on how he validates his forecasts. He may predict a storm in a 3-day window in October, but the chances of a depression crossing the UK in any 3-day period in October is fairly high. Does it count as a success if he predicts gales and flooding and it's just damp and a bit breezy?

 

Stu, there are independant verification pdf`s on the Weather Action site.

He claims 85% success rate, not 100%. As the weather is mostly quiet or uneventful for much of the time, his successes may go un-noticed for much of the time. The examples n which you pick Andy would have a web presence because of the nature of the event. Maybe that constitutes the 15% errors .

Except the link I provided earlier credits him with much less than a 85% success rate.

It all depends on how he validates his forecasts. He may predict a storm in a 3-day window in October, but the chances of a depression crossing the UK in any 3-day period in October is fairly high. Does it count as a success if he predicts gales and flooding and it's just damp and a bit breezy?

Well he did once claim success because he'd forecast a deep depression to the SW with gales and a storm surge affecting SW England ........ and there was a storm in the Baltic instead!

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As far as I'm aware no-one has attempted a comprehensive independent review of his accuracy but I did bother to look at one month a while ago (think it was Dec 2009) which wasn't very good.

I've done a few assessments and find that whilst he may sometimes do reasonably well in terms of general trends (ie wet & windy second half of the month), he falls down a lot on specifics and of course he has had a few well documented 'disasters'.

For example, he wonders why the Govt still ignore him - after sending them a warning a catastrophic flooding in August 2007 ......

(and he did forecast that the weekend of the July 2007 floods hit here would be one of the few periods that month which were going to be warm, dry and sunny with no flooding)

When the Nov 2009 floods hit Cumbria he had, to be fair, warned of flooding and a storm surge .... In East Anglia ......

http://weatherearthnews.blogspot.com/2009/11/19th-november-flooding-in-britain.html

The wetest days were the 20th and 23rd July, either side of the weekend, and both within the forecast periods for heavy rain and floods. That weekend was actually the shortest dry period forecast on the whole month`s forecast.

If you want to inspect it, mail me and I will forward it.  [email protected]

 

Thks, I already have his forecast, which reads:

"17-19th Rapidly becoming
wet or very wet with hail &
floods. Windy & cool.
Low pressures sweep in from West
as High pressure recedes. Deep
Low develops in Scandinavia later.
Enhanced tornado risk - Mod
Aurora likely
20-21st Dry fine & bec
warm or v warm & humid.
High pressure builds from North as
shallow lows wallow to
South/SouthWest."

The synoptic situation was completely different to what he forecast.  And the rain fell on the 20th/21st.

And if you keep forecasting floods in July every few days, then there's a very high chance that somewhere or other a thunderstorm will produce a flash flood within a day or so of one of the periods you said flooding would occur!   But he did not predict the nature, intensity, type or synoptic situation that actually did produce the floods.  An epic fail IMHO.

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As far as I'm aware no-one has attempted a comprehensive independent review of his accuracy but I did bother to look at one month a while ago (think it was Dec 2009) which wasn't very good.

I've done a few assessments and find that whilst he may sometimes do reasonably well in terms of general trends (ie wet & windy second half of the month), he falls down a lot on specifics and of course he has had a few well documented 'disasters'.

For example, he wonders why the Govt still ignore him - after sending them a warning a catastrophic flooding in August 2007 ......

(and he did forecast that the weekend of the July 2007 floods hit here would be one of the few periods that month which were going to be warm, dry and sunny with no flooding)

When the Nov 2009 floods hit Cumbria he had, to be fair, warned of flooding and a storm surge .... In East Anglia ......

http://weatherearthnews.blogspot.com/2009/11/19th-november-flooding-in-britain.html

The wetest days were the 20th and 23rd July, either side of the weekend, and both within the forecast periods for heavy rain and floods. That weekend was actually the shortest dry period forecast on the whole month`s forecast.

If you want to inspect it, mail me and I will forward it.  [email protected]

 

Thks, I already have his forecast, which reads:

"17-19th Rapidly becoming
wet or very wet with hail &
floods. Windy & cool.
Low pressures sweep in from West
as High pressure recedes. Deep
Low develops in Scandinavia later.
Enhanced tornado risk - Mod
Aurora likely
20-21st Dry fine & bec
warm or v warm & humid.
High pressure builds from North as
shallow lows wallow to
South/SouthWest."

The synoptic situation was completely different to what he forecast.  And the rain fell on the 20th/21st.

And if you keep forecasting floods in July every few days, then there's a very high chance that somewhere or other a thunderstorm will produce a flash flood within a day or so of one of the periods you said flooding would occur!   But he did not predict the nature, intensity, type or synoptic situation that actually did produce the floods.  An epic fail IMHO.

That would be tricky if there were no floods in a given July ! Persionally looking at the whole forecast, I would be more concerned about the lack of floods around the 9th to 12th. I am very conversant with solar forecasting, and would of myself picked the 20th as a very wet day. (only 28.6mm max on the 21st).

Is this you on WUWT Breezy?

And so many think that volcanoes cause cooling, despite the lack of evidence after the the majority of large events.

Are you able to back this up? My master's thesis was about cooling after large volcanic eruptions.

Is this you on WUWT Breezy?

And so many think that volcanoes cause cooling, despite the lack of evidence after the the majority of large events.

Are you able to back this up? My master's thesis was about cooling after large volcanic eruptions.

 

You should have looked at cooling before them. How many can you name where you think there is cooling after the eruption?

http://img297.imageshack.us/img297/16/krakatoata5.png 

 

 

and what do you make of this 

The effects of an eruption that size might last five or six years. Your graph only shows three.

 

Show us a fifty year span with Krakatoa in the middle and then we'll talk.

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Is this you on WUWT Breezy?

And so many think that volcanoes cause cooling, despite the lack of evidence after the the majority of large events.

Are you able to back this up? My master's thesis was about cooling after large volcanic eruptions.

 

You should have looked at cooling before them. How many can you name where you think there is cooling after the eruption?

http://img297.imageshack.us/img297/16/krakatoata5.png 

What am I supposed to make of it? There was cooling after the eruption, which occurred in August.

http://www.woodfortrees.org/plot/rss/from:1991/to:1995 .

http://www.woodfortrees.org/plot/hadcrut3vgl/from:1991/to:1995  (looks really noisy but actually has a smaller range than RSS - cooling still evident as it's the only time since 1985 that the Hadley global anomaly was below zero.)

http://www.woodfortrees.org/plot/hadcrut3vgl/from:1963/to:1967 . Cooling is evident there too.

http://www.woodfortrees.org/plot/rss/from:1981/to:1985 

So of the last 3 major eruptions, I say two caused cooling and one had its cooling masked by the biggest El Nino on record (at the time).

http://climate.envsci.rutgers.edu/pdf/ROG2000.pdf 

They show a large decrease in direct solar radiation following eruptions (because volcanic aerosols scatter sunlight) and a smaller rise in diffuse solar radiation, again due to scattering (figure 2 in particular). Let's take Pinatubo as an example, and see that the peak reduction in direct solar radiation, measured in Hawaii, is from ~530W/m2 to ~390W/m2, a drop of ~140W/m2. The concurrent rise is diffuse radiation is from ~40W/m2 to ~140Wm/2, a rise of ~100W/m2.

How do you propose this observed decrease of incoming radiation of ~40W/m2 does not have the effect of cooling the Earth's surface?

 

So of the last 3 major eruptions, I say two caused cooling and one had its cooling masked by the biggest El Nino on record (at the time).

 

I thought you might try to give a long lists of events with cooling following, not that there really is enough to make such a list, as warming usually follows large events. The woodfortrees graphs you show are lower troposphere, that is not surface temp`s. The cooling of the lower trop` 92 would more likely be due to increasing low cloud cover.

So you want to claim 3 months cooling of 0.2C after Krakatoa then ? Mid 1885 goes a bit cold briefly, that`s too late by then though, the aerosols would have washed out by then.

Ok, 1783 Laki eruption, England under the ash cloud for 3 months continuosly, with the pavements so hot you could fry meat on them , according to Rev Gilbert White ???

I you had 3 or 4 ceturies worth, with many events that show cooling in European monthly temperature series, I might take you seriously.

 

 

http://climate.envsci.rutgers.edu/robock/robock_volpapers.html 

What about the radiative physics? 40W/m2 is a lot.

and what do you make of this 

The effects of an eruption that size might last five or six years. Your graph only shows three.

 

Show us a fifty year span with Krakatoa in the middle and then we'll talk.

 

5 or 6 years ? never.

50yrs ? no point talking with you, you make no sense.

 

http://climate.envsci.rutgers.edu/robock/robock_volpapers.html 

What about the radiative physics? 40W/m2 is a lot.

40W of what visible wavel length, what about IR bands ?

Probably a super greenhouse effect occurring with the aerosols, especially if they are dark.

Anyway, if you check your large events data you will see the bigger temp` drops are before the eruptions and not after.

and what do you make of this 

The effects of an eruption that size might last five or six years. Your graph only shows three.

 

Show us a fifty year span with Krakatoa in the middle and then we'll talk.

 

5 or 6 years ? never.

50yrs ? no point talking with you, you make no sense.

 

Yes by 3 years the vast majority of the aerosol would be gone. A longer time period would however help with seeing the effects in context and compare it to other natural variability.

BTW I realise I reglected to respond to your point about Laki. Two rebuttals:

First, you're not considering the global or even hemispherical effects. Yes it's clear NW Europe was incredibly hot that summer. But there was also extreme cold to follow shortly afterwards in the USA and Europe. But instrument records are not comprehensive enough to draw conclusions about what Laki did to the global climate.

Second, Laki was far from your typical explosive eruption. For 8 months it spewed lava and sulphur containing gases into the troposphere forming a vast cloud of volcanic fog. Usually these tropospheric aerosols are washed out in days to weeks, but these were constantly replenished. It is theorised, but of course far from proved, that the nature of this smog in the stagnant weather pattern Europe had that summer contributed to the intense heat by absorbing solar radiation.

Meanwhile Laki also had several exlosive episodes capable of injecting sulphur into the stratosphere, where aersols have a longer lifetime. After the dissipation of the tropospheric haze this would have an effect over the next 2-3 years.

 

http://climate.envsci.rutgers.edu/robock/robock_volpapers.html 

What about the radiative physics? 40W/m2 is a lot.

40W of what visible wavel length, what about IR bands ?

Probably a super greenhouse effect occurring with the aerosols, especially if they are dark.

Anyway, if you check your large events data you will see the bigger temp` drops are before the eruptions and not after.

The aerosols interact only weakly with IR because the size of sulphate aerosols, about 0.5 microns, is similar to the wavelength of visible light and considerably smaller than the wavelength of IR. Also, the power of the sun's visible output is much more than its IR output:

 

These effects combined mean that the effect on the visible is much greater. A warming of the stratosphere is observed due to aerosols absorbing a bit of visible and (mainly terrestrial) IR. This in turn can warm the poles a bit during the polar winter by re-radiating to the surface but the prevalence of water vapour's effect on the IR spectrum elsewhere make this effect negligible.

So overall the effect in the visible is significantly larger.