Model Output Discussion 18z 28/07/13

[Frosty.]

wasn't we suppose to be in a start of a heatwave? So what went wrong?

The heatwave is on friday, enjoy it.

[TonyH]

Hardly heat and hardly a wave though!

[SnowBallz]

The 06z ensembles show temperatures holding up pretty good for the next few weeks rainfall looks like remaining low as well

 

 

*my 10,000th post*

 

 

Wow, congrats on the 10,000 - excellent dedication!! 

 

Bit random but a few of my colleagues are just beginning to take a keen look at the data trends for DJF and the current leaning - albeit very small sampling at the moment - is towards another anomalously colder winter season.  It's a very small degree of confidence though, so not - at this stage - worthy of any great thoughts.  Data churn with reanalysis will continue through to around the 3rd week in September, by which time they'll be far greater depth of data available.  The experts in this field say that the early data is always prone to anomalies as they tend to run various different sample code against it.  By the way, an SSW field is being parsed into the GRID for this coming winter, so it will be very interesting to see results against that.  I'm not sure they're using it in production though, possibly just development.

 

Anyway enough of my waffling - still waiting for winter here!

[mushymanrob]

wasn't we suppose to be in a start of a heatwave? So what went wrong?

 

ironically, it almost makes those of us that wrote off summer (in terms of a spell of 25c+ days) correct!

 

The heatwave is on friday, enjoy it.

 

its a few hours, if we are lucky, cloud is spilling in from the west and will cover most of the uk by 4pm according to this mornings graphics on the bbc... it was supposed to be several days, now its a couple of hours...

 

will the azores high ridge in next week? if so how far?

 

the ecm (00z) will be the coice of most here i suspect as it shows the high becoming displaced and drifting across us bringing a hot sunny spell, temps into the mid 20's. the gfs (00z) hold it back next week, never bringing it over us, leaving us in much cooler, slack north westerlies.

[Frosty.]

GFS 00z is looking good, High pressure dominating for the next few weeks, sometimes centred just to the west of the uk but extending a ridge across but the tendancy is for the anticyclone to become centred over the top of the BI, it looks a pretty settled run to me after the warm showery blip during the next 3-4 days.

[Captain Shortwave]

the ecm (00z) will be the coice of most here i suspect as it shows the high becoming displaced and drifting across us bringing a hot sunny spell, temps into the mid 20's. the gfs (00z) hold it back next week, never bringing it over us, leaving us in much cooler, slack north westerlies.

Well from the last week or so the ECM has been the pain in everyones backside, usually producing the worst output for the UK, being a complete outlier and then being proved right. Oh look it's doing it again....

 

Can the 2C isotherm stay away until October please 

Edited August 22, 2013 by Captain shortwave

[Frosty.]

The Ecm 00z operational run initially looks similar to the Gfs 00z with the flabby weekend trough slowly drifting away southeastwards into mainland europe allowing pressure to rise from the southwest & northeast with a narrow band of high pressure which replaces the weekend warm mix of sunshine and showers & light winds with a few days of fine and pleasantly warm weather with sunny spells and light winds, but, then it all goes wrong as a spoiler trough digs down from the north and becomes a real pesky feature for the east and southeast of the BI with a core of cool air, the anticyclone is forced to pull westwards into the atlantic, there would be showers or longer periods of rain for the east/se of the uk later next week but high pressure to the west would make it drier and brighter the further west you are.

Edited August 22, 2013 by Frosty039

[johnholmes]

Looking towards the month end and start of autumn (meteorogically speaking) and the 3 main 500mb anomaly charts all to a fairly large degree support the idea of a ridge being in control rather than a trough. The flow looks to be from north of west not south so cloud amounts and temperatures are still to be decided. Over the northern hemisphere their current indications suggest no more than 3 major troughs which can often lead to fairly static conditions. Perhaps the experts on MJO movements may be able to suggest when this might change?

 

To my amateur eye the MJO would currently find it hard to get closer to the origin on the plots so little indication there. The prediction, if it is currect is for it to move into phase 1 at a reasonable orbit, not good news really on the 500mb composites, see below

http://www.americanwx.com/raleighwx/MJO/MJO/SeptemberPhase1500mb.gif

 

How accurate this will be remains to be seen.

 

sorry it will not open it-can anyone help please, it is fine on my pc?

Shows essentaiily low heights over/west of UK and high way west and also east of uk?

Edited August 22, 2013 by johnholmes

[Frosty.]

As with the Gfs 00z, the GEFS 00z mean is looking warm and settled for the next few weeks with high pressure in control until early september once this weekend's shallow trough clears away to the southeast, the mean is smooth sailing into a nice warm final week of summer and first week of autumn with light winds and long sunny periods with temperatures into the low 20's celsius, nearer mid 20's c for the south & east at times.

[johnholmes]

The above post by frosty is a fair indication, at least in terms of surface pressure values, of the support from the 500mb anomaly charts. That is not the same agreement as saying the position of the surface high will be as shown throughout that run!

Edited August 22, 2013 by johnholmes

[Summer Sun]

The pick of the models this morning if its high pressure you want is most certainly UKMO

 

 

With low pressure firmly in charge over Greenland and the Azores heading back to the UK we *could* be in for another lenghthy settled spell of weather and pleasent temperatures to go with it

[thunderhead 2005]

So what happened to the trough that was slipping down from the NE

[snowking]

Wow, congrats on the 10,000 - excellent dedication!! 

 

Bit random but a few of my colleagues are just beginning to take a keen look at the data trends for DJF and the current leaning - albeit very small sampling at the moment - is towards another anomalously colder winter season.  It's a very small degree of confidence though, so not - at this stage - worthy of any great thoughts.  Data churn with reanalysis will continue through to around the 3rd week in September, by which time they'll be far greater depth of data available.  The experts in this field say that the early data is always prone to anomalies as they tend to run various different sample code against it.  By the way, an SSW field is being parsed into the GRID for this coming winter, so it will be very interesting to see results against that.  I'm not sure they're using it in production though, possibly just development.

 

Anyway enough of my waffling - still waiting for winter here!

First of all SB, congratulations on the information in your signature

 

Completely agree with the above, not too sure about December at this juncture but plenty of signals for the main bulk of the cold to start around the middle of January, with February having looked, for quite some time, like the month with the potential to be the coldest of the winter period - and really rather cold at that! The composite years I have churned up so far using a combination of QBO, ENSO and PDO projections, are 1978/79 and 1990/91 - both cooler winter periods. The biggest thing of interest is the relationship between the QBO and solar maximum state. Somehow last year we managed a rather large SSW with an Easterly QBO under solar maximum conditions, where as the favoured relationship in terms of the BDC is for a Westerly QBO under such solar conditions...so if anything, the chances of an SSW already seem higher (assuming we stick with the Westerly QBO).

 

Anyway...back to the here and now. We seem to be having the carrot dangled in front of us again....it feels like winter already, though this time of course everybody is chasing the warm, settled conditions.

 

We of course await the ECMWF ensembles now, but given recent experience, I would not be comfortable with this showing from the Ensemble mean:

 

 

For as long as the core of the ridge is shown to be South-West of the UK, you always risk what we are about to experience this weekend, with a 'weakness' in pressure left just to the East, or indeed across the UK, and at this time of the season, with the Jet getting ready to fire up somewhat as the natural thermal gradient strengthens, you cannot afford to leave any gaps in the pattern!

 

SK

[stodge]

Morning all

A rare day off for me so a rare chance to comment on the models but it's all been said so I've nothing much to add.

It would be nice for the rest of us to have a chance at analysing the output.

The bulk of the output looks anticyclonic but fans of heat look to be out of luck with the main centre of HP always to the SW or West. It may be that a lot of Atlantic cloud rather hampers the development of prolonged sunshine especially as the days are getting shorter but it will obviously be very pleasant and above all comfortable.

As others have said, if the "gap" between the Azores HP and its Scandinavian counterpart gets too extended, a trough can split the two HP centres and bring a spell of much less settled conditions.

GFS FI also suggests pressure falling over Scandinavia which, while not materially affecting much of the British Isles, again doesn't promise heat but keeps things settled.

[Frosty.]

I agree with snowking but I also think that the ecm 00z op run will have little in the way of support with it's pesky trough, next week should be generally fine with the azores high becoming the controlling influence.

Edited August 22, 2013 by Frosty039

[Tamara]

Wrt ECM mean it is always worth taking a look at what the individual EPS members are showing. This not only will give a fair spread representation of other models ideas (especially UKMO and GFS) but it also puts into some perspective of how a mean chart might transfer in reality to an idea of pressure placements that transfer to what the weather on the ground might be like for the UK. By this I refer to whether or not the High will be prone to the weaknesses to its east, as interestingly discussed this morning, or if the mean has been skewed by an outlier or two (or three!)

 

Taking into account all of the above considerations, then I would suggest that the ECM operational, to start with, has dug the trough too close to the east in accordance with a graemlin it seems to be producing these days to over amplify the jet stream in its latter day output (approx) 6/7 and on from there.  Obviously there is something of a myriad of solutions as one would expect amongst 51 members, but I think it is a fair enough judgement to suggest that the south, at the very least, looks set for a return to some fairly settled conditions once weekend and early week showers have dissapated. We see the best case scenario from the UKMO this morning and whilst this could be a tad too optimistic there are some solutions amongst the EPS members that reflect this and GEFS mean as well described by Karl above lends some support, at least, to this. However, we must take into account the propensity for the jet stream to send fronts across more north western areas from time to time.

 

 

For the moment, at least, I would be sceptical of the more amplified solutions that dig any trough further south about 6 days and more out. Time and again they are flattened out and corrected north with time, and whilst sooner or later this extra amplification will indeed occur, I think that we await the seasonal polar vortex gathering later in the autumn for that to produce the extra energy in the system which is still lacking.

 

One thing in the meantime that could change things, at least temporarily, could be any extra energy sent into the jet stream through a recurving ex tropical system

Edited August 22, 2013 by Tamara Road

[Frosty.]

The Ecm 00z ensemble mean has a lot more in common with the Gefs 00z mean /gfs 00z op & ukmo 00z than it does with the ecm 00z operational run. The azores/atlantic anticyclone ridging northeastwards across the uk brings a fine and pleasantly warm spell to most of the uk with temperatures into the low 20's celsius, only the far north of the uk looks more changeable at times due to some ebb and flow with the ridge, atlantic weather would brush around the top of the ridge and across the far north at times but generally it looks good for a decent spell of end of summer  / early autumn weather with benign and pleasant conditions which could evolve into a much warmer spell if the azores high builds in properly.

Edited August 22, 2013 by Frosty039

[Tamara]

I agree with snowking but I also think that the ecm 00z op run will have little in the way of support with it's pesky trough, next week should be generally fine with the azores high becoming the controlling influence.

Hiya - I think the caveat to that might be the risk of fronts brushing to the north keeping things less settled there

[Frosty.]

Hiya - I think the caveat to that might be the risk of fronts brushing to the north keeping things less settled there

Indeed Tamara, as I have explained in my above post.

[johnholmes]

Morning all

A rare day off for me so a rare chance to comment on the models but it's all been said so I've nothing much to add.

It would be nice for the rest of us to have a chance at analysing the output.

The bulk of the output looks anticyclonic but fans of heat look to be out of luck with the main centre of HP always to the SW or West. It may be that a lot of Atlantic cloud rather hampers the development of prolonged sunshine especially as the days are getting shorter but it will obviously be very pleasant and above all comfortable.

As others have said, if the "gap" between the Azores HP and its Scandinavian counterpart gets too extended, a trough can split the two HP centres and bring a spell of much less settled conditions.

GFS FI also suggests pressure falling over Scandinavia which, while not materially affecting much of the British Isles, again doesn't promise heat but keeps things settled.

 

an understandable feeling but you do have to be early beat both frosty and mushy at the moment!

Your view is just as valid though as anyone else assuming that you give a balanced view and explain your thoughts?

don't get put off.

 

a quick note.

re the idea of the surface highs Azoes-Sandinavia linking up and folk worrying of the danger of them being split by a low pressure system. Do not, yet, build up any hopes that this is 'real, the 2 highs linking that is, nothing on the anomaly charts suggests this on their recent outputs. I'll let you know if that changes.

Edited August 22, 2013 by johnholmes

[draztik]

The EPS control model (ecm) shows a blocking high form over the UK from t240 to 360. So, i suppose confidence is growing for a settled longer term outlook, with 10-12 uppers associated with this HP.

Edited August 22, 2013 by draztik

[No Balls Like Snow Balls]

Looks like there could be a cooler NWerly flow setting up for next week. ECM and now GFS op runs hinting at this. How ever will remain pleasently warm South of UK but will be a lot cooler in the North. GFS / ECM mean 500mb chart today also hinting at NWerly flow.

 

 

 

 

Some chilly night time temps associated with possible new flow

 

 

Getting excited about the approaching Autumn and Winter now :-)

 

 

Edited August 22, 2013 by No balls like Snow Balls

[Frosty.]

The Gfs 06z operational run shows the azores/atlantic high there or thereabouts throughout the run but it doesn't have things entirely it's own way, the ridging occasionally pulls back west and allows lows to slide southeastwards and bring some cooler and more unsettled intervals but these are mainly across the north/ne, the further south & west you are, the higher the pressure would be with the longest dry and fine spells between some relatively weak frontal interruptions, however, eventually the azores anticyclone does build in across the uk and intensifies before drifting east and becoming centred just to the east of the uk which enables much warmer continental air access to the uk, it's a fantastic end to this run but it's hard work getting there but the effort would be very rewarding for the majority of us who are hoping for another fine and very warm spell before autumn begins to close in, overall it's not a bad run with a mix of average to warm temperatures, above average sunshine totals and only relatively small amounts of rain but some cool nights.

Edited August 22, 2013 by Frosty039

[Timmytour]

 

One thing that all the models show is by the 20th high pressure in charge.

  

That's true for the timebeing, but I think the high pressure has struggled to reassert itself since its heyday in July, and i can't help thinking that this pattern will be maintained, with the models hinting but reality not quite delivering.I think the latest ECM op will prove to be a trendsetter and perhaps keep all but perhaps the most southeastern parts away from the glorious bank holiday weather we want. Not that it will be particularly bad, especially the more south you are, but nothing in the "special" category.  But I'd stress that's me thinking where the models first over the next few days and then reality will take us, which is not where there are at this moment in time

My comment was supposed to put a jinx on things going wrong!!!!I still think the overriding pattern shown by the models since the breakdown of the heatwave in July is to show the high looking like it will dominate from the South in a timeframe...but for it actually not to materialise to anything like the degree

[Frosty.]

The GEFS 06z mean shows a more robust azores/atlantic anticyclone compared to the 6z op run, the high pressure cells to the southwest & northeast link up for a time which they were very reluctant to do on the op run and eventually the azores high takes over, unlike the op run, the mean looks more generally settled and pleasantly warm with only the far north of the BI exposed to any atlantic influences with occasional weak fronts brushing around the top of the ridge, some ebb and flow in the position of the azores/atlantic high is to be expected with lower pressure and the PFJ rippling across greenland across to iceland and northern scandinavia, at least the PFJ remains well to the north until well into september and pressure continues to be relatively high across the south of the uk, any erosion of the overall set up looks very slow and drawn out and we could now be looking at a fine and warm spell next week and the following week away from the northern half of scotland. In the meantime, some heavy showers around, especially across the east of the uk on saturday, but sunday becoming drier and brighter from the west but also fresher, the shallow trough across the southeast should clear southeastwards into the near continent to leave a fine end to the weekend and a decent bank holiday monday, with generally fine weather persisting throughout next week, warmest and sunniest further south.

 

Finally, tomorrow looks like being hot and sunny across the southeast of england with temperatures as high as 29-30c 85F but further to the north and west it will be less good with more cloud and a few splashes of rain here and there.

Edited August 22, 2013 by Frosty039