Model Output Discussion 18z 28/07/13

[johnholmes]

It will certainly be interesting to see how the models deal with 'Humberto', how close they are to what it actually does. How much effect on the loger wave pattern it may have. A really interesting period coming up for short and longer range model watching.

 

for detail on 'Humberto' and its expected movement/development. Interesting that they suggest the Azores high will be responsible for it moving NW for a time before another trough moving out of Canada picks it up as it then re develops into a mjor Atlantic storm.

link below

http://www.nhc.noaa.gov/text/refresh/MIATCDAT4+shtml/121439.shtml?

Edited September 12, 2013 by johnholmes

[ANYWEATHER]

Well, it looks like ecm and gfs are holding hands a T+96!!!

[johnholmes]

Well, it looks like ecm and gfs are holding hands a T+96!!!

 

yes even down to 'Humberto'

[Summer Sun]

ECM ensemble following the GFS ensemble at t216 and t240 with the Azores building out west settling down the Atlantic again

 

GFS ensemble to compare

 

 

Very good agreement between the 2 almost identical on the placement of the high

 

Edited September 12, 2013 by Summer Sun

[johnholmes]

ECM ensemble following the GFS ensemble at t216 and t240 with the Azores building out west settling down the Atlantic again

 

 

GFS ensemble to compare

 

 

 

Very good agreement between the 2 almost identical on the placement of the high

 

 

Don't be too surprised if, in spite of cross agreement, for the reasons I think it was ba mentioned earlier, the ensembles by their very nature will not necessarily show the track/position of the ex hurricane 'Humberto'. So some changes are to be expected.

[draztik]

ECM ensemble following the GFS ensemble at t216 and t240 with the Azores building out west settling down the Atlantic again

 

GFS ensemble to compare

 

 

Very good agreement between the 2 almost identical on the placement of the high

 

yes, but thereafter the gfs ens slide, with lower pressure. The update from the ec32 will be interesting to see tonight.

[Frosty.]

I think the ecm 12z looks very messy late in the run, there is no continuity between the 0z and 12z today, this is why i'm sceptical about it's reloading unsettled pattern of cool winds and rain, more runs are needed.

[Captain Shortwave]

Actually the ECM/GFS are very similar up to T144, then there is a big difference between the two come day 7

ECM

 

GFS

 

GFS is sending a lot less energy east towards us which means the Azores ridge doesn't not flatten as much and allows the high to build in afterwards. 

You can't really use any bias or other arguments here, ECM has a flatter jet caused by more energy push east from the US, whilst the GFS has less energy and a more amplified jet which allows the Azores high to build back in.

[Tony27]

ECM ensemble following the GFS ensemble at t216 and t240 with the Azores building out west settling down the Atlantic again

 

GFS ensemble to compare

 

 

Very good agreement between the 2 almost identical on the placement of the high

 

what's the thumbs up about? you make it sound as if this high pressure is set in stone when those charts are at 216, if you looked at the 500mb charts for today it had a ridge of high pressure over us but here it was 16c and cloudy, there is a signal for high pressure in FI  but it could just be cloudy and average like today if the high isn't strong enough, it will be sods law if september is autumnal and chilly and my crops go rotten, and then we get 25c in october

[SMU]

Heres a punt - watch ALL the ensembles trend towards the jet moving south for day 8 in the next 24/ 48 hours-  Everyone says the Ensembles are the way forward, however until the resolution can compete with the resolution of the operational they are OFTEN a long way wide of the mark-

 

 

A couple of points to ponder-

 

ENSEMBLES will follow climatology for the month-  especially past day 6 as the model accuracy is replaced by more & more historic bias fed into trending-

This is ALWAYS prevalent in the GFS-

 

September climo is THIS

 

 

However the 5 year recent anomaly is this-

 

 

you will note the considerable polar blocking V the Normal- the assumption I am making is that due to the reduced thermal gradient across the pole Autumn climo is quickly changing across the NH - from a strong +AO to frequent bouts of -AO & the UK could well oscillate between cold & warm bouts.- ( moreso recently coder interludes as the cold actually grows into continental Europe)

 

therefor the model bias in this AUTUMN scenario will always want to gravitate to the seasonal historic bias which in this case will be an elongated azores high ridging NE to the UK, when infact this may well end up a very much muted signal as we go from T192 into T120 as the models get a grip on the jet & the associated jet streaks & shortwaves-

 

Hence my above punt that the models & ensembles will move towards the ECM operational.

 

THE NET SPIN HERE IS ALL ENSEMBLES WILL POS TILT THE JET SE NW- = elongated Azores High

Reality will be - More polar blocking = A jet tilted more NW SE- aligning the shortwaves cutting SE over the UK....

 

 

 

 

Also a picture of how bad the GFS was in winter last year -

 

 

ACTUAL CHART-

 

14 JAN 2013 -- A trough slides south over the UK-  ECM modelled every day that evolution & the UMNO- GFS has the trough over SVALBARD!!

 

T144 9th of JAN 00z 144

GFS

 LOW OVER SVALBARD

 

ECM 9th of Jan 00z 144

  TROUGH OVER SOUTHERN ENGLAND opening the easterly flood gates-

 

 

 

it took the GFS until the 11th on the 12z to finally get there-

 

Why - GFS easterly bias.....

 

hope this helps.

S

Edited September 12, 2013 by Steve Murr

[Frosty.]

There remains a lot of support for a fine and warm further outlook beyond next week according to todays gefs mean 00z, 06z and 12z plus the ecm 00z and 12z ensemble mean, the overall trend continues to show the autumn stormy depression gradually losing its potency and drifting away northeastwards into scandinavia as a filling feature which will then enable the azores/atlantic anticyclone to ridge across the uk by the end of next week, I have seen nothing to change my views on that today.

[Cheshire Freeze]

Heres a punt - watch ALL the ensembles trend towards the jet moving south for day 8 in the next 24/ 48 hours-  Everyone says the Ensembles are the way forward, however until the resolution can compete with the resolution of the operational they are OFTEN a long way wide of the mark-

 

 

A couple of points to ponder-

 

ENSEMBLES will follow climatology for the month-  especially past day 6 as the model accuracy is replaced by more & more historic bias fed into trending-

This is ALWAYS prevalent in the GFS-

 

September climo is THIS

 

SEPTCLIMO.png

 

However the 5 year recent anomaly is this-

 

Sep2007-.png

 

you will note the considerable polar blocking V the Normal- the assumption I am making is that due to the reduced thermal gradient across the pole Autumn climo is quickly changing across the NH - from a strong +AO to frequent bouts of -AO & the UK could well oscillate between cold & warm bouts.- ( moreso recently coder interludes as the cold actually grows into continental Europe)

 

therefor the model bias in this AUTUMN scenario will always want to gravitate to the seasonal historic bias which in this case will be an elongated azores high ridging NE to the UK, when infact this may well end up a very much muted signal as we go from T192 into T120 as the models get a grip on the jet & the associated jet streaks & shortwaves-

 

Hence my above punt that the models & ensembles will move towards the ECM operational.

 

THE NET SPIN HERE IS ALL ENSEMBLES WILL POS TILT THE JET SE NW- = elongated Azores High

Reality will be - More polar blocking = A jet tilted more NW SE- aligning the shortwaves cutting SE over the UK....

 

 

 

 

Also a picture of how bad the GFS was in winter last year -

 

 

ACTUAL CHART-

 

14 JAN 2013 -- A trough slides south over the UK-  ECM modelled every day that evolution & the UMNO- GFS has the trough over SVALBARD!!

14 Jan 2013.png

 

T144 9th of JAN 00z 144

GFS

00zGFS9th JAN.png  LOW OVER SVALBARD

 

ECM 9th of Jan 00z 144

00zECM9th Jan.gif   TROUGH OVER SOUTHERN ENGLAND opening the easterly flood gates-

 

 

 

it took the GFS until the 11th on the 12z to finally get there-

 

Why - GFS easterly bias.....

 

hope this helps.

S

 

It's the same rigmarole every time though Steve....you just won't get through to some people. No matter how many times they witness such things with their own eyes. I've never seen such a poor modelling example from a 'top 3' model as the GFS portrayed at the beginning of the year. As you say, the ensembles were next to useless aswell. I remember saying, they're only as good as the run they've come from.

 

Quite a few times I've seen the GFS ensemble suite flip in the space of 1 or 2 runs.

 

Sometimes the GFS seems very reluctant to split energy into the southern arm of the jet- again as we saw last winter. Probably, as you say, as a result of climatological bias programmed into the model.

Edited September 12, 2013 by CreweCold

[Captain Shortwave]

We will have to see Steve too be honest, being on here during the summer the ECM op has frequently cried wolf on this NW/SE pattern past day 6 only for it to backtrack a few runs later. Frankly no model has done well over the summer months to be honest with some shocking performances with regards to some cut off low formations during August.

The major headache here is Humberto, the pattern may scream the sinking jet but that storm which contains a lot of energy might completely trump the meridional pattern and push the Azores high back over us which pretty much resets the pattern back to where we were in August. 

With the Joker of the pack in play as some might say, I'm keeping an open mind to where we go.

[Cheshire Freeze]

I'm keeping an open mind to where we go.

 

Probably for the best at present.

[chionomaniac]

That is a pretty staggering anomaly chart for September from the last 5 years Steve.

 

It made me look at the anomaly charts for the last 5 years for winter - again we see the theme of a very disrupted polar vortex:

 

December

 

 

January

 

 

February

 

 

I believe that we will follow a similar pattern this winter - west QBO or not.

[john pike]

updated fax charts for monday and tuesday

 

press f5 a few times if still showing yesterdays date

 

 

[Cheshire Freeze]

 

I believe that we will follow a similar pattern this winter - west QBO or not.

 

Ohhh Chiono you big tease!

[Captain Shortwave]

Well this is what the GFS is now saying for a weeks time

 

Humberto ejected at a different time, more runs needed on this little bugger.

[Frosty.]

Will humberto give us the hump or come up trumps? That is the question tonight.

[Cheshire Freeze]

Will humberto give us the hump or come up trumps? That is the question tonight.

 

Trumps? Does look a bit windy around the core I'll give you that.

[Gaz1985]

Next Friday we start to see the Pressure rise, it is still an ongoing trend which cannot be ignored, might be a nice dry mild end to the month which would tie into the Met Office prediction hope fully. 

 

[Frosty.]

Trumps? Does look a bit windy around the core I'll give you that.

Lol.

[Frosty.]

Yes gaz the 18z is looking good and following the favoured trend of the met office, long may it continue.

[draztik]

The ECM control from t240 to 360 continues with the cool theme, with 4/5 uppers throughout.

Yes gaz the 18z is looking good and following the favoured trend of the met office, long may it continue.

settled, yes, warm, no. Surprised you favour this, based on what you have said recently.

[Frosty.]

The ECM control from t240 to 360 continues with the cool theme, with 4/5 uppers throughout.settled, yes, warm, no. Surprised you favour this, based on what you have said recently.

The ecm 12z ensemble mean charts that gavin posted earlier are trending in favour of a pleasantly warm benign further outlook, as is the gefs 12z mean.