Model Output Discussion 18z 28/07/13

[Jezzer]

Just been in twitter contact with Simon King, 5-Live's met forecaster, he says:

 

"signs that big high might well persist beyond the weekend too"

[Scorcher]

^{With the UKMO and ECM both differing at T120 anything after this is pure speculation, however there certainly looks like a spell of settled weather early next week with temps in low 20's (certainly not headline news). Could possibly turn unsettled again after midweek. I don't see any hot weather on the horizon.}

 

Low 20s? Think it would be much warmer than that in the south no matter which model you look at this morning.

[Frosty.]

This morning's Ecm 00z ensemble mean is the best looking mean I have seen since the July Heatwave, just look at that continental heat heading into the uk later next week, it looks very impressive with the high moving into the perfect position to enable the hot & sultry airmass to spread up across the uk, this mean would bring heat to rival july and more hot and sultry nights with hazy scorching sunshine but also an increasing risk of storms breaking out, either homegrown or imported from france, it would bring a classic end to this excellent summer, absolute perfection for hot weather fans, a rerun of the heatwave last month, whether we tap into the continental heat or not, it looks very much like the uk is going to have a very nice summery spell spreading up from the south as the anticyclone builds in, the PFJ is forced to retreat well north towards the arctic...it's an EPIC ens mean. 

Edited August 16, 2013 by Frosty039

[No Balls Like Snow Balls]

Low 20s? Think it would be much warmer than that in the south no matter which model you look at this morning.

Yeah for my place down south Mon and Tues next week only 20c.

[shedhead]

I have to respectfully disagree.The GFS and its ensembles are  solid their projection of a very fine and warm settled spell of weather and ecm 0z is a vast improvement on the 12z yesterday.So,with that in mind,your last comment is patently not true.

Take a look at the gefs 0z ensembles AND the ecm0z mean right out to 240h,they are both sublime and bring about as good a synoptic pattern as you could wish to see in August.

I have to respectfully ask you to read my post properly then HD. 

 

You highlight this 'So classic case of more runs needed, but what I said 24hrs ago still stands imo, i.e a nationwide heatwave is still as far away as it's ever been...indeed it may even be a little farther away this morning.' but then suggest this... The GFS and its ensembles are  solid their projection of a very fine and warm settled spell of weather.

 

When does a 'very fine and warm settled spell of weather' = a nationwide heatwave?

 

Moreover, when do we simply rely on GFS alone?

 

Nationwide warmth and sunshine (note nationwide!) is still by no means guaranteed next week, the possible LP coming in off the Atlantic midweek still  has the potential to throw a significant spanner in the works for the north and west in particular...so as I said - more runs are needed.

Edited August 16, 2013 by shedhead

[TonyH]

I have to respectfully ask you to read my post properly then HD. You highlight this 'So classic case of more runs needed, but what I said 24hrs ago still stands imo, i.e a nationwide heatwave is still as far away as it's ever been...indeed it may even be a little farther away this morning.' but then suggest this... The GFS and its ensembles are solid their projection of a very fine and warm settled spell of weather.When does a 'very fine and warm settled spell of weather' = a nationwide heatwave?Moreover, when do we simply rely on GFS alone?Nationwide warmth and sunshine (note nationwide!) is still by no means guaranteed next week, the possible LP coming in off the Atlantic midweek still has the potential to throw a significant spanner in the works for the north and west in particular...so as I said - more runs are needed.

How often would nationwide apply to a warm mainly dry spell such as we are about to experience?

[shedhead]

How often would nationwide apply to a warm mainly dry spell such as we are about to experience?

When people read posts like this Tony....

 

This morning's Ecm 00z ensemble mean is the best looking mean I have seen since the July Heatwave, just look at that continental heat heading into the uk later next week, it looks very impressive with the high moving into the perfect position to enable the hot & sultry airmass to spread up across the uk, this mean would bring heat to rival july and more hot and sultry nights with hazy scorching sunshine but also an increasing risk of storms breaking out, either homegrown or imported from france, it would bring a classic end to this excellent summer, absolute perfection for hot weather fans, a rerun of the heatwave last month, whether we tap into the continental heat or not, it looks very much like the uk is going to have a very nice summery spell spreading up from the south as the anticyclone builds in, the PFJ is forced to retreat well north towards the arctic...it's an EPIC ens mean.

 

Anyone from Littlehampton to Lerwick reading the above would expect at the very least a 'warm mainly dry spell' and that to be fair is putting it mildly.

Edited August 16, 2013 by shedhead

[Frank Trough]

meanwhile, the shortwave is back on the 06z!

 

[Paul]

A final reminder - we're taking a zero tolerance approach to personal snipes and attacks in here now, so a number of people are on seriously thin ice this morning. Please moderate yourselves before hitting the post button or the likelihood is that a few will be stopped from posting in here with no further notice...

[shedhead]

meanwhile, the shortwave is back on the 06z!

 

Looks far enough west not to do to much damage on that chart PC...let's see where it goes later though before drawing to many conclusions.

[Frank Trough]

Looks far enough west not to do to much damage on that chart PC...let's see where it goes later though before drawing to many conclusions.

 

yes, it just sort of dies a death....bit of a midweek washout for the Hebrides and northern Scotland if it's right, though. 

[legritter]

Morning gang ,things are already hotting up on Net weather even before any warm spell arrives ,we must ALL take a good look at our post before hitting that button .plenty of action weatherwise and a very good chance looking at current data of a good v warm spell next week .lets grab it with open arms ,some excellent data still being posted on our brilliant forum ,we also have the possibility of some action weather out in the very very long range frames of modells so plenty to keep us on our toes .

[Tamara]

Good morning boys Its healthy for you all to be passionate like this - lets also be nice to each other

 

I am going to start with the trusty EPS members as reference because i think within them you can get a sense not just of where the ECM is plotting ahead, but you can also see myriads of the permutations the other models may be showing. Looking at these this morning one can see some of the cleaner solutions that Lorenzo well described earlier amongst them, as depicted by the models - and I think that confidence can be taken from this to suggest that High pressure will evolve the other side of the niggly little low towards midweek.

 

I think that notwithstanding shortwavegatedot.com then the prognosis here to follow that is a solid variant of a pressure build out to the end of next week to see increasingly warm weather across the bulk of the UK. That doesn't inextricably mean it will be settled everywhere nationwide however. Rarely is it that straightforward in the UK. But most all of the members show permutations of High pressure in the vicinity and also what features in many cases is weakness of pressure down to the south west. In this sense then the operational ECM is well supported this morning

 

 

In terms of how long the High pressure may last...well how long is a piece of string? Chances are reasonable taking into the background factors as well described yesterday evening f.e, that it will be sustained through to the end of the month although it could well be punctuated by temporary attempted breakdowns. As I see it, this suggests the macro pattern is one in the main of one High pressure cell replacing another at mid latitudes and within the micro detail this maybe resulting in weakening cold front features being squeezed out in situ and perhaps leading to fitful and sporadic sharp, possibly thundery, showery outbreaks. Especially in view of the fact that much of Europe to our south especially will have a lot of very warm/hot and humid air present. The +16 isotherm (at least) always very close by.

 

However, a week is long enough away to look at things at present and chances are pretty good that we are looking to arrive at the August Bank Holiday in good shape. Best we don't jinx the Bank Holiday itself just yet..we know how fickle these can be   

[Captain Shortwave]

Ironically  06Z output ends up better than the 00z for the majority if you are looking for very warm temperatures. Maybe there will be a blip in the North west on Wednesday, but apart from that it still looks pretty good. In fact the presence of the shortwave gives the warmer uppers a real kick northwards with the 18C isotherm lapping into the south west by the end of high resolution.

 

 

 

Can't really argue here, 12C uppers for all and even higher in the south 

I think the ECM op has overdone the low and actually see this run as a reasonable solution, if the shortwave makes it to the North west of the UK.

Edited August 16, 2013 by Captain shortwave

[mushymanrob]

T+120 hours FAX chart, welcomes back high pressure and the 564 dam line, summer is coming back with a BANG next week, initially for the south and then extending up across the uk as the anticyclone continues to build in, the evidence supporting a return of very summery weather far outweighs anything else.

 

hi karl

 

that fax chart worries me, that shortwave is too close for comfort, and the models are struggling to nail its exact impact on our weather. adding the anomaly charts into the equasion (and listening to what john and others have said) then i do think theres room for concern. the models may well all be showing some fantastic outputs for sun/heat, but if that shortwave doesnt play ball then everything after t120 - t144 is fantasy... as i see it, it MIGHT all go wrong yet. if no one can nail the synoptic charts at t120 then everything else must be treated with caution.

 

you know me, theres no one here who wants another hot spell more then what i do.... but the pain of possible disappointment outweights ramping excitement when there is justified cause for concern...

 

until that pesky shortwave has been dealt with and its threat of spoiling removed, ill not be happy! i would be happier with more anomaly chart support, after all, the shortwave might only be a delaying feature to the real warmth.... or it might herald something less then currently predicted on the ops.

 

meanwhile, the shortwave is back on the 06z!

 

 

thats good news, it tracks it further northwest then what the fax suggests.... but which is more accurate at t120? the ever excitable gfs or the more sober fax?...

[mushymanrob]

well... these look great! pity they all disagree with eachother...

 

[summer blizzard]

well... these look great! pity they all disagree with eachother...

 

test8.gif

Similar to the 12z yesterday the GFS wants to build a swathe of heights to the north. Still warm for now but a setup that could well evolve to something cooler in the future.

[Tamara]

The essence of this I think as suggested earlier is that the shortwave is unlikely to have any effect on a build of high pressure afterwards - alas it simply provides potential nuisance value to areas further north and west during next week. This is highlighted by the METO anyway. As CS points out it could well serve to help assist some pretty warm air northwards though, but the total extent of this is uncertain.

 

I don't think the minor details should get in the way of the larger scale pattern - that is really the point. Its not worth worrying about anyway as its the weather and will do what it does  *she adds untechnically*

Edited August 16, 2013 by Tamara Road

[johnholmes]

 

Good to get an old fashioned model debate going and will provide interest over the weekend where CPC guidance not written, as usual we will be into Monday 12z until we get a true picture. Good to have John and Mushy placing the caveats on things, with the deterministic models not in good agreement at day 5 then a little ways to go on this one yet.

I have to pick you up on this L; over 3 years I have never seen more than a couple of, at that doubtful instances, when the NOAA 500mb anomaly ouput showed a difference that could be attributed to the factor you quote. I did have correspondence with NOAA about 4 years ago. Their answer was that the lack of forecast input was in the technical summary rather than the actual NOAA 6-10 and 8-14 chart outputs. If I get a chance I may send another e mail and ask if in their view the NOAA 6-10 and 8-14 over weekends and BH's show any differences other than the obvious day to day differences one sees throughout the runs?

Edited August 16, 2013 by johnholmes

[mushymanrob]

The essence of this I think as suggested earlier is that the shortwave is unlikely to have any effect on a build of high pressure afterwards - alas it simply provides potential nuisance value to areas further north and west during next week. This is highlighted by the METO anyway. As CS points out it could well serve to help assist some pretty warm air northwards though, but the total extent of this is uncertain.

 

I don't think the minor details should get in the way of the larger scale pattern - that is really the point. Its not worth worrying about anyway as its the weather and will do what it does  *she adds untechnically*

 

im almost with you, but its the larger scale pattern that has its doubts. if i viewed only the ops, id be pretty convinced of a decent lengthy settled warm spell...hot even at times, but i cant get past johns analysis of the anomaly charts. a 70% accuracy rate when the charts are in agreement for 3 runs is pretty impressive.... the current problem is is that the three used do not agree, unlike july when they did. now to my way of thinking, if theres going to be a substantial pattern change away from the atlantic driven one we have now, to a protracted spell of high pressure dominance, it would show NOW in those anom charts and they would agree... or maybe this is a case of where the 30% is right (i assume the 30% where they dont agree and the ops are right? )

[Frosty.]

WOW the Gfs 06z op run certainly does have the wow factor about it, it's anticyclonic from early next week until the end of august with signs of a reload by the end and a brief half hearted atlantic breakdown for the north but the majority of the latest gfs run is absolutely spectacular with very warm and settled weather across the whole of the uk, hottest across the southern half of the uk with temps in the 27-31c range as the heat eventually builds in from the near continent, nearer 24-26c for n.ireland & scotland which would be way above average. The Ecm 00z ens mean and now this run add yet more concrete evidence that we are heading into a sustained very summery pattern through next week and the following week with the PFJ  half way across greenland and into the arctic where it can't bother us for a while, the 6z is anticyclonic heaven, it's showing warm, very warm and hot weather with increasing humidity, the outside chance of a few isolated storms being triggered eventually but the main emphasis is on glorious late august sunshine and a perfect end to a great summer, we could not ask for more.

[Jax]

Looks like summer is far from over just yet.

[Tamara]

 

im almost with you, but its the larger scale pattern that has its doubts. if i viewed only the ops, id be pretty convinced of a decent lengthy settled warm spell...hot even at times, but i cant get past johns analysis of the anomaly charts. a 70% accuracy rate when the charts are in agreement for 3 runs is pretty impressive.... the current problem is is that the three used do not agree, unlike july when they did. now to my way of thinking, if theres going to be a substantial pattern change away from the atlantic driven one we have now, to a protracted spell of high pressure dominance, it would show NOW in those anom charts and they would agree... or maybe this is a case of where the 30% is right (i assume the 30% where they dont agree and the ops are right? )

I think the answer lies in the fact that we are unlikely to see a whole-hearted nationwide fine spell for part of the time at least.  As stated earlier, i think it is probable that it will be punctuated by a few interruptions and showers - and I hesitate to mention it because it sounds rather IMBY, but southern and eastern areas look most favoured for the best conditions. That is simply as it looks, and genuinely not intended to suggest any partiality whatsover. That said, I think that the latter part of next week and into the weekend, at the very least, looks good for most of us across the UK

 

If we look at the updated extended NAEFS mean, it does suggest that north western most parts may be at risk of a few inroads from atlantic weather fronts once more after the Bank Holiday weekend. But this is clearly beyond the boundaries of any reliability atm

 

.

Edited August 16, 2013 by Tamara Road

[lorenzo]

I have to pick you up on this L; over 3 years I have never seen more than a couple of, at that doubtful instances, when the NOAA 500mb anomaly ouput showed a difference that could be attributed to the factor you quote. I did have correspondence with NOAA about 4 years ago. Their answer was that the lack of forecast input was in the technical summary rather than the actual NOAA 6-10 and 8-14 chart outputs. If I get a chance I may send another e mail and ask if in their view the NOAA 6-10 and 8-14 over weekends and BH's show any differences other than the obvious day to day differences one sees throughout the runs?

 

Happy to be picked up on this as elevates the subject and I know it is a topic that keeps on coming back in Model discussion, what I was meaning regarding the 6-10 day and 8-14 day upper air tools is that the prognostic discussion is not written over the weekend. I find this part of the guidance useful as it explains the thoughts of how they blend the solutions on offer and gives some insight into where a model is off kilter, too quick or showing an anomaly. Also the rating of the general outlook in terms of agreement with the score out of 5 weighting is a good indicator of the expected pattern. Not in dispute at all about the charts. 

 

The links I have that do update over a Saturday and Sunday are these ones - 

 

WPC Discussions  and within that front page the extended analysis

 

Edited August 16, 2013 by lorenzo

[len]

Hello,

Sorry if I'm posting this request in the wrong thread?

Posters often put up the monthly NH composites for MJO phases here.  My link for these now goes to "American Weather"

 

As anyone got a new link for these monthly phase composites please?

 

Thanks