Model Output Discussion 18z 28/07/13

[Frosty.]

Pity as it would be nice to get some interesting weather instead of dire settled boredom.

Long may the dire settled boredom continue

[bradymk]

Indian summer: What exactly is it?

 

http://www.bbc.co.uk/news/magazine-15127159

 

As has been said above the low pressure doesn't have any support high pressure is the form horse at the moment keeping things quiet and dry

 

 

Not entirely, UKMO and ECM are similar at 144, GEM 00z also showed a similar setup. Although i think ECM may be an outlier tonight and may be a bit extreme, it can't be ignored but the chart is a week out still. Hope its wrong though, looking forward to more settled warm weather

[Cheshire Freeze]

The ECM can't really be dismissed outright as an outlier at 168 hours as the UKMO also shows slightly more amplification at 144 hours than the GFS.....albeit not to the same extent as the ECM. If the pattern was to amplify sufficiently and we get the high wandering further NW and the trough digging further S we will see the ECM eventuality.

[bluearmy]

Not entirely, UKMO and ECM are similar at 144, GEM 00z also showed a similar setup. Although i think ECM may be an outlier tonight and may be a bit extreme, it can't be ignored but the chart is a week out still. Hope its wrong though, looking forward to more settled warm weather

 

indeed brady - the past 10 days should have taught us that a lack of mean upper ridge leaves us prone to the surface features changing 

 

             

 

just three ops for day 6 from today (admittedly one is chinese so doesnt really count) that support the non sustained ridge scenario

[Cloud 10]

Complete change at t168 this evening with cooler strong north westerly winds sweeping down

 

 

The ECM has developed a habit this summer of over-amplifying the jet stream,so will be interesting to see

if that 168 hrs chart verifies.

 

I can imagine some drama in here if it continues with its over-amplication during the winter!

[johnholmes]

Don't worry about the ecm gavin, i'm sure it will turn out to be a rank outlier for that period, the ecm has been a bit poor recently, hope it gets it's act together in time for winter.

these are the latest statistics for the northern hemisphere. Unless someone can show that in the European theatre the above comment is true I'm not sure the comment is correct?

http://www.emc.ncep.noaa.gov/gmb/STATS/html/new_acz6.html

[BlueHedgehog074]

In a way, I kinda agree with CrewCold. While it might not be the most accurate model out their, even the 12Z NAVGEM, at 144 hours, seems to have the Low Pressure system next week trying to dig right towards us at 144 hours (though I reckon it's probably being even more extreme than the ECMWF is, since those low heights are further South than that model):

 

Your Worst Nightmare! (if you're after something sunny and settled) ;-)

 

Even the South probably wouldn't get away with dry weather for next Friday on that run. It does, nevertheless, go to show that next week isn't properly nailed yet - at least for the later part of it anyway. We'll have to see whether the ECMWF and NAVGEM become more GFS-o-fied. Or whether the GFS becomes more NAVGEM-o-fied or ECMWF-o-fied. Should the former happen, then the warm, settled, bright, (and possibly lengthy) spell could stay intact.

Edited August 24, 2013 by DiagonalRedLine

[johnholmes]

Indian Summer is a period of warmth after the first frosts. Origin is in parts of North America and usually means in November. But rarely applies to the UK.

 

Nothing to do with September or October.

I did post the official Met O definition a few days ago, there is no mention of frost for the UK and it refers to the months of October and November, the term was introduced into this country at the beginning of the 19 C, according to the Met O Glossary.

[Joe8987]

Some of these charts are showing multiple weeks of warm weather. Don't you think that's a bit unrealistic at the end of August? When was the last time we had a couple/few weeks straight of warm/settled weather at the end of August/beginning of September?

[Summer Sun]

No surprises to see the ECM op is an outlier this evening

 

 

High pressure is the way forward for a while yet

 

Some of these charts are showing multiple weeks of warm weather. Don't you think that's a bit unrealistic at the end of August? When was the last time we had a couple/few weeks straight of warm/settled weather at the end of August/beginning of September?

 

Not really TBH we can still get some high temperatures for another 4 or 5 weeks yet

[BlueSkies_do_I_see]

Some of these charts are showing multiple weeks of warm weather. Don't you think that's a bit unrealistic at the end of August? When was the last time we had a couple/few weeks straight of warm/settled weather at the end of August/beginning of September?

Good question. This thread discusses it in detail!

http://forum.netweather.tv/topic/77617-late-august-hot-spell-how-rare/

The 1906 heatwave is the most famous late summer into Sept event. 2nd Sept hit 35.6C that year..

Edited August 24, 2013 by BlueSkies_do_I_see

[bluearmy]

these are the latest statistics for the northern hemisphere. Unless someone can show that in the European theatre the above comment is true I'm not sure the comment is correct?

http://www.emc.ncep.noaa.gov/gmb/STATS/html/new_acz6.html

 

good stats JH

 

points to note: re day 6

 

number of occasions in august that model was clear ahead of the others:

 

GFS: 3

ukmo: 5

ecm: 16

 

infact there were only 3 occasions when ecm wasnt in the first two verifying models on a particular day.

 

surprising how poor GEM has been this month. hasnt seemed that bad to me but you cant argue with the stats !

[Scorcher]

I did post the official Met O definition a few days ago, there is no mention of frost for the UK and it refers to the months of October and November, the term was introduced into this country at the beginning of the 19 C, according to the Met O Glossary.

 

Indeed, a lot of people are using the American definition and applying it to the UK. If it refers to air frost then Indian summers are virtually non-existent here as once an air frost occurs it's usually too late in this country to get temperatures above 20C. In the north east of the US however it's quite feasible for an air frost to occur and then be followed by temperatures in the mid 70s even into November.

 

The ECM this evening is a bit disappointing from 168 hrs but thankfully it's just outside the reliable timeframe and will hopefully turn out to be an outlier. Overall though a mostly dry, sunny and warm week coming up for most which will be a great way to end August.

[bluearmy]

No surprises to see the ECM op is an outlier this evening

 

 

it is gavin ?

 

 

 

you cant judge an outlier from a mean chart.  the op has support. whether its right is a different question.

 

the anomoly for day 7 even clearer 

 

 

Edited August 24, 2013 by bluearmy

[Summer Sun]

Indeed, a lot of people are using the American definition and applying it to the UK. If it refers to air frost then Indian summers are virtually non-existent here as once an air frost occurs it's usually too late in this country to get temperatures above 20C. In the north east of the US however it's quite feasible for an air frost to occur and then be followed by temperatures in the mid 70s even into November.

 

The ECM this evening is a bit disappointing from 168 hrs but thankfully it's just outside the reliable timeframe and will hopefully turn out to be an outlier. Overall though a mostly dry, sunny and warm week coming up for most which will be a great way to end August.

 

The ECM ensemble charts I posted above seem to show its not got much support

 

it is gavin ?

 

EEM1-192.gif

 

 

you cant judge an outlier from a mean chart.  the op has support. whether its right is a different question.

 

Well that was an ensemble chart I posted that's why I said its an outlier

Edited August 24, 2013 by Summer Sun

[bluearmy]

thats not right gavin. an outlier is a run which has no support from the remaining ensemble members. (given ecm has 51 members in the suite, we'll say 'little support'). clearly, that spread chart shows that there are a cluster of ens members that take the depression just to our ne. hence the op is NOT an outlier. you cant judge an outlier from a mean chart. you can say the op in unsupported by the mean. however, until you look at the spreads, you have no idea how reliable the mean is.  

Edited August 24, 2013 by bluearmy

[Summer Sun]

thats not right gavin. an outlier is a run which has no support from the remaining ensemble members. (given ecm has 51 members in the suite, we'll say 'little support'). clearly, that spread chart shows that there are a cluster of ens members that take the depression just to our ne. hence the op is NOT an outlier. you cant judge an outlier from a mean chart. you can say the op in unsupported by the mean. however, until you look at the spreads, you have no idea how reliable the mean is.  

 

Ah fair enough I must check the anomoly charts as well in future

 

Further on there is support for rising pressure though

 

[Frosty.]

thats not right gavin. an outlier is a run which has no support from the remaining ensemble members. (given ecm has 51 members in the suite, we'll say 'little support'). clearly, that spread chart shows that there are a cluster of ens members that take the depression just to our ne. hence the op is NOT an outlier. you cant judge an outlier from a mean chart. you can say the op in unsupported by the mean. however, until you look at the spreads, you have no idea how reliable the mean is.

Jeez why are you arguing about it? You sound like you are hoping the outlook will be cool unsettled dross. There is a lot more support for a warm settled outlook as things stand.

[DTHFCJ]

Gavin is right, there is currently a lot more support for a warm settled high pressure dominated outlook.

Im confused very confused,i check the ops,check the mean now its check the spreads....which one is more reliable

ECM spreads NAEFS anomolies..... its confusing this weather lark think il stick to hating arsenal

[bluearmy]

Oh dear. How dreadful to state the facts about the output. Go back a week or so karl and look at the forecast charts for this weekend.

Gav made a statement that the op was an outlier, this would lead folk to believe there is little chance of the op verifying. I was merely pointing out that the op was not an outlier and it probably has a 1 in 5 chance ( have to wait till the london ens come out to know for sure what the number is) of happening. ( based on the 12z suite)

Edited August 24, 2013 by bluearmy

[DTHFCJ]

Jeez why are you arguing about it? You sound like you are hoping the outlook will be cool unsettled dross. There is a lot more support for a warm settled outlook as things stand.

Frosty you have made my summer this year,top top enthusiastic posts well done mate...gotta say Bluearmy is very good come summer or winter always says it how it is and shows no preferences  hats off to you both

 

sorry off topic mods

id better add... trust me i aint after no brownie points if you knew me youd know,gotta give credit where is due

Edited August 24, 2013 by DTHFCJ

[No Balls Like Snow Balls]

If we were to believe the means all the time then the last 2 weeks at least should have seen us in heatwave conditions with no rain. But yet we have barely above ave temps and torrential rain in some parts today. Seeing is believing. And all this memorable summer malarky, really ?, yeah its been nice for the most part but memorable hmmm

Edited August 24, 2013 by No balls like Snow Balls

[draztik]

If we were to believe the means all the time then the last 2 weeks at least should have seen us in heatwave conditions with no rain. But yet we have barely above ave temps and torrential rain in some parts today. Seeing is believing.

actually, the ensembles never truly supported what the ops were showing recently. For example, when the ops, primarily the gfs showed heatwave conditions for last week, the ensembles showed time and time over that the op was an outlier. as for todays output, there have been subtle changes, in terms of how strongly the high builds in. But i still believe that hp will indeed build, and we should see a settled pattern. Have been a bit disappointed by the ecm lately, and expect to see another change in the morning. For me, hp looks like being in control, with only the far NW being prone to less settled conditions at times.however, i will concede, the ensemble mean still has the core of the high to our west, meaning changes to our north, could see troughs digging in. More runs, as usual, are needed. Edited August 24, 2013 by draztik

[Tamara]

The ECM has yet again suggested amplification of the jet stream at 7 days and digging a trough further south east.

 

It isn't worth arguing about   but based on what we have seen this summer then we could, at least at the present time, take the latest suggestion with another further pinch of salt.

 

Sooner or later this recycled Azores High ridging will take on a different slant, probably as seasonal wavelengths and thermal gradients increase and as the annual polar vortex cycle starts to re-awaken, but for now maybe we can sleep in our beds with a season of mellow fruitfullness to follow and look forward to  

 

Hopefully then, as Cloud 10 hints at, it will start to change dramatically in late November/early December and set the pattern for the winter time as many of us would wish  How is that for a premature girly ramp? Enjoy the rest of the Bank Holiday, and dry out asap, if it is rather a soggy flavoured theme atm

Edited August 24, 2013 by Tamara Road

[BlueHedgehog074]

The ridging from the High Pressure cell on the GFS 18Z is looking quite decent and managing to have enough power to fend off the Low Pressure system tracking to the North of the UK for late next week and beyond. And although there appears to be some amplification of the High Pressure system, it seems comfortably close enough to us to prevent a Low Pressure system from digging some of its low heights South-Eastwards towards us, just like what happened on the 12Z ECMWF.

 

18Z GFS @ 168 hours

 

12Z ECMWF @ 168 hours

 

When looking further ahead up to 240 hours on this new GFS run, I think it is safe to say that the GFS doesn't want to be pals with ECMWF's 12Z run. Overall, it is a generally settled run (except for possibly the deepest part of Fantasy Island). But, if the GFS can continue with quite a High Pressure dominated outlook on future updates (like it had also done on the previous GFS run), then I think there is only one place where that ECMWF 12Z run will end up in - the trash can! Mwhe he he he hee...

Edited August 24, 2013 by DiagonalRedLine