In Depth Model Discussion and Summaries

[Thundery wintry showers]

Agreed, looks like many parts of the UK will be cloudy on Saturday and Sunday, with a generally warm sunny day for most on Monday. I think the northern half of England will see a fair amount of sunshine coming through on the afternoon of Saturday 4th May, in between the trailing fronts sat over Scotland and southern England.

http://www.wetterzentrale.de/pics/brack0a.gif

On Sunday we have a warm front moving eastwards which will bring cloudy and humid tropical maritime air.

http://www.wetterzentrale.de/pics/brack1a.gif

The FAX chart for Monday shows a trailing front persisting over northern Scotland where it will probably be grey and damp, but the southerly flow elsewhere should bring drier, sunnier conditions in off the continent. It won't be outstanding for warmth but maximum temperatures of 20-22C are likely in the Midlands and south of England.

http://www.wetterzentrale.de/pics/brack2a.gif

The models are suggesting a breakdown from the west between the 7th and 9th May, but it will probably be short-lived (the ECMWF operational run does not have much support for its ensembles). Indeed, there is a fair amount of support for an anticyclonic spell between the 10th and 14th which could bring a fair amount of warm sunshine wherever the high covers, though the further north and west you are, the less of a guarantee there is of much in the way of sunshine.

The MJO is forecast to shift towards phase 3, and the composites for phase 3 suggest anomalously low pressure to the north of the British Isles.

http://raleighwx.americanwx.com/MJO/MayPhase3500mb.gif

Phase 4 then has composites showing low heights to the E and NE of Britain. I feel that we are likely to see low pressure extend its influences south-eastwards after midmonth which may turn the weather cooler and more changeable, at least for a week or so, over southern and eastern Britain following a dry first half of May, but confidence beyond mid-May is quite low.

[johnholmes]

It may be a good idea for folk to be able to see what the 3 main anomaly charts are showing to supplement what I posted this morning, and I’ll copy this into the model thread as well.

The NOAA output for last evening and the link gives access to the 6-10 and 8-14 day outlooks

Remember that the 6-10 is probably a closer comparison usually with the ECMWF-GFS which is for 10 days ahead than the 8-14 may be.

Taking the ECMWF-GFS output first

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

This morning the two models showed roughly similar patterns. In that they both had a broadly westerly 500mb flow over the Atlantic and UK. Differences where in how far south or north the troughing effect was being predicted. GFS had this further south which is why I commented about it showing unsettled weather further south than ECMWF did.

Turning to the latest NOAA output from last evening

The 6-10 is not that different from the charts shown above with it perhaps more like ECMWF than GFS.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Of course any analysis is always subjective when done by humans so some of you may well be less in agreement with my assessment. It is also best to remember that one set of charts, much as one run or one model should not be taken in isolation. Nor should we ignore other drivers over a similar time scale, so always make sure they are checked. If all of them, or most of them are suggesting roughly a similar pattern then we can allocate a higher degree of confidence to our forecast. If one is markedly different then less confidence and so on. As a personal thing I always wait for 2-3 days of outputs on the anomaly charts before suggesting the likely upper air pattern. Although there are exceptions which I find I can make after studying these charts pretty much every day for the last 3 years.

So my overall feeling over several days is that they are indicating a slight change to a more westerly flow but still with signs of upper ridging in the near Atlantic hence my idea of some degree of north to south difference in actual surface weather. Depending on just where the higher height values actually occur along with strength of the 500mb flow will depend on where the weather is more settled or unsettled.

Hope this is of some help to some of you.

John

Edited May 4, 2013 by johnholmes

[Cloud 10]

Looking at the height anomalies across the northern hemisphere for the last week or so,it seems

that the polar vortex is stronger than normal for the time of year which is resulting in a +ve NAO general weather pattern for the UK.

 

 

 

 

Looking towards the middle of May the general pattern looks fairly similar,although as mentioned

in John's post above perhaps becoming a bit more unsettled and cooler especially the further

north you are.

 

The ECM and GFS ensemble means show good agreement on this.

 

ECM..  GFS..

 

 

Beyond the middle of May and especially to the start of June the polar vortex should become

much less influential as the final warming of the stratosphere begins to finish it off.

 

 

 

 

So it begs the question,what weather pattern can we expect to see for the start of summer?

 

 

 

Edited May 4, 2013 by Cloud 10

[johnholmes]

copied from the model thread

anomaly charts as of sat 11 may 2013 their view.pdf

[Jack Wales]

Just thought I’d post some quick thoughts in here with summer now very much on the horizon…

Following on from my recent post in the ‘Summer’ thread, the northern hemispheric pattern appears to be reflecting the recent ENSO neutral and positive AAM pattern; this combined with increased MJO activity and the recently favourable Atlantic SST profile should teleconnect with a northerly displaced Azores high with heights / ridging towards Scandinavia.

This type of pattern now falls into the modelling timeframe and with the PV finally diminishing; this type of pattern is being picked up from around T+204. This chart at GFS T+324 shows the kind of synoptics which should set the scene for late May and into early June with heights ridging up from the Azores…

http://cdn.nwstatic.co.uk/gfsimages/gfs.20130516/00/336/airpressure.png

This is also reinforced up by the surface heights ensembles with the mean levels forecast at around 1020 mb from around T+240 onwards….

Going forward into late June and the rest of summer, I have some concerns in that the ENSO pattern is trending to more negative tendencies (La Nina) which would be less conducive for settled conditions over NW Europe. Here are the latest SST’s where you can clearly observe the negative anomalies propagating westward towards Nina 3.4…

http://weather.unisys.com/archive/sst/sst_anom-130512.gif

The eagle eyed may also notice that the Atlantic SST profile is not looking quite as favourable as it was just a couple of weeks ago.

There are no signs yet that the atmosphere is starting to re-embrace La Nina, e.g. one of the firsts indications would be for Total Angular Momentum to plummet to negative values, whereas at present the latest AAM data is still positive...

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif

If the upper level westerlies can filter down and scrub the lower level easterlies currently prevalent over the equatorial pacific (and assisting the ENSO- trend), this could halt La Nina in its tracks. An amplified MJO could also help facilitate this, so in my opinion the next couple of weeks could be crucial in terms of what the building blocks for this summer will be.

[BornFromTheVoid]

Going forward into late June and the rest of summer, I have some concerns in that the ENSO pattern is trending to more negative tendencies (La Nina) which would be less conducive for settled conditions over NW Europe. Here are the latest SST’s where you can clearly observe the negative anomalies propagating westward towards Nina 3.4…

http://weather.unisys.com/archive/sst/sst_anom-130512.gif

 

Hi JW, 

Latest ENSO forecast if for neutral conditions to remain throughout the summer

 

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

[Jack Wales]

Hi BFTV,

Yes, the CPC have been forecasting ENSO neutral for a while now, however I can't help but feel they're underestimating the potential for La Nina. A visual observation of the Pacific is clearly indicitave of a developing La Nina, which is backed up by increased negative anomalies across the ENSO Zone...

ENSO 1&2: -1.6C

ENSO 2 -0.5C

ENSO 3 -0.1C

ENSO 4 no anomaly

As I say, the longer the low level easterlies remain in place, the more scope there will be for the negative anomalies to propagate to the key 3.4 region.

However MJO activity is on the rise and tropical convection is projected to emerge in a pattern consistent with MJO phase 8. This (to me) suggests a greater possibility for scrubbing of the low level easterlies by the end of the month as the atmpspheric pattern is not (yet anyway) consistent with La Nina.

It's definately on a knife edge at the moment with some conflicting signals but I believe there is more reason to be hopeful for more 'summery' spells this summer. I'll try and spend some time on this over the weekend and hopefully post something more substantial.

[johnholmes]

copied from the Met O forecast areas

outlook from me sat 25 may 13.pdf

[AWD]

I thought I would post in here for the first time ever as the other thread seems to be more "searching for High Pressure and nothing else" bar the usual few of course. For those with a general meteorological interest, here is a more unbiased post (hopefully).

Tomorrow looks like another widespread, sunny day with temperatures getting up to the high teens and perhaps very low 20c's around the London area;

Monday looks like an occlusion will spread in from the west, sitting over west Wales by midday;

This means a rather wet and miserable day for Wales, Ireland and Western Scotland with moderately heavy rainfall here;

Dry still further east, although clouding over ahead of the occlusion as the day progresses;

Temperatures cool under the rain in the west, maybe up into the high teens in the east still;

The occlusion makes slow progress east/south east Monday night, clearing the south east Tuesday morning, although by this time there looks to be little PPN left on it for the south east;

On Tuesday, there looks to be further rainfall over the southern half of the UK, due to a trough pepping up instability here to form frequent, slow moving, prolonged showers and spells of rain;

Further north it looks cloudy but drier, with just patchy, inconsequential rainfall around. Temperatures, unsurprisingly, down on recent values to typically low single figures;

Wednesday and Thursday both look similiar to each other, with a slack trough pattern over or close to the UK providing a mix of sunshine and slow moving downpours. Too early to say if anything thundery or any thunderstorms could develop.

That's the reliable timeframe anyway. After tomorrow, changeable is the best way to describe the weather. Looking further out briefly and we see some evidence of the Azores pressure cell moving NE over or close to the UK. For relevance purposes the GFS Op at Day 10;

And ECM Op at Day 10;

Both show this scenario, albeit in differing locations. Ignoring the positioning, the trend is there on both. However, we all know NWP output this far out is a lottery, so what do other atmospheric measurement tools show?

Well, the GEFS 850hpa suite for Aberdeen;

And London;

clearly show a return to average and perhaps slightly above average temperatures as we enter meteorological summer. However, if we look at the pressure suites for both locations;

And rainfall suites;

There are scenarios there that show rainfall is still possible at both locations, albeit small amounts as you would expect. This would suggest that the conditions felt where you are on the ground in the UK could differ greatly depending on the location the Azores HP cell drifts too. A long way from calling a nationwide settled spell yet I feel, although I'm obviously not saying it won't happen, just saying it's too early to say.

Looking at the 500mb anomaly charts, you can see clearly the broad theme of a ridge from the SW moving NE over or near to the UK;

The ECMWF version showing a very pronounced ridge just to the north of the UK. Both scenario's show NO heat wave conditions and both show the possibility of a certain part of the country being affected by showers running around the flank of the HP cell.

Taking a snippet from the Met Office medium range forecast;

"Little change is expected as we head through the first week of June, with temperatures remaining rather cool, but locally warm in some northern and western parts, at least for a time."

This too me would suggest something similiar to what the ECM model is suggesting, with HP to the north of the UK;

That's a strong signal from the ECM too. Therefore the most settled weather would be for the northern half of the UK, with the southern half, especially the far south always prone to more showery conditions being closer to lower pressure. The ECMWF temperature anomaly also showing the further north you are the warmer it will be;

So maybe the north could be the better place to be come June? That would be a rarity, and indeed, based on tonight's runs, a possibility. Either way, a lot of weather to get through before any possible settled spell materialises though. No sign of any heat wave conditions, far too early and uncertain to call a nationwide settled spell and far too premature to try and prelude the length of any settled spell IMO.

This can be seen by the latest EC 15 day ensemble forecast issued today. A climb in temperature through the beginning of June visible, but as I said, a long way from anything resembling a heat wave, with average temperatures typically;

Low rainfall projections for the beginning of June too, but note the last couple of days;

A slight uptick at the very end there. Could this be the first sign of a relaxation in pressure come the second week of June? Who knows, it could equally mean convective potential. Bear in mind these ensembles are for Birmingham too, the middle of the UK.

That's how I see it anyway. Too sum it up, typical late Spring, early Summer weather. No washout, no heat wave. :)

Edited May 25, 2013 by AWD

[johnholmes]

many thanks AWD-no need to be over technical in here. A very nice clear presentation from various models which I am taking the liberty of commetning on in the model thread as it is well worth reading for the less technical and is mercifully free of bias. thanks again

[J10]

A good post there AWD, but I do think you are understating the High Pressure potential given the recent outputs and the recent forecast charts for June as per here.

 

 

I have been looking at the CFS forecasts for June and July for the Glastonbury festival, off which this forecast will appear either tonight or over the weekend.

 

 

June

 

June 13 Temps (24 May).png June 13 Rainfall (24 May).png June 13 Pressure (24 May).png

 

July

 

July 13 Temps (24 May).png July 13 Rainfall (24 May).png July 13 Pressure (24 May).png

 

Both don't appear too bad especially June, with pressure higher than average to the west of UK. Notice in particular how low the pressure is forecast to be over Greenland in June.

[AWD]

I'll post in here again as I doubt this will prove too popular in the other thread.

We have some notable differences in the medium range outlook between the main group of NWP models. Leaving out the UKMO model for the time being, as with it's limit of 144 hours, you can't really get a full picture of where we are heading next week with that model. The GFS model is keen to bring us a nationwide, settled start to meteorological summer, with the Azores pressure cell influencing the weather for most of us next week, as shown by it's Day 10 chart;

The ECM model however, shows a more temporary visit of the Azores pressure cell before it retreats westwards allowing a trough to influence our weather for most of us by Day 10:

So differences here. What I will say is we do have good agreement now of a predominantly settled weekend and start to next week, it's more a case of is it going to be prolonged as per the GFS or temporary as per the ECM.

Lets look at the 12z ECM ensembles for London (0z ones not out yet).

Rainfall;

You can see from those that there are plenty of members going for increased rainfall scenarios as we go into the end of next week.

Temperature;

A trend to increase temperatures after the cooler start to next week there.

I won't dwell too much on these suites, as they are last nights. A look at the latest De Bilt ens;

Show the ECM Op to be a generally well supported run, always close to the mean and followed closely by the control run. Again, you can see there that there is a case to call for a slow increase in temperature as well as an increase in rainfall as we go through next week. We can see below that the EC ensemble suite support the ridge of pressure into the start of next week;

Which slowly pulls back west as next week progress's, allowing more unsettled conditions into the east with time;

A look at the SLP GEFS for London show the Operational to be more or less an outlier in it's final stages, with a clear drop in pressure shown after Day 10, so a but later than the EC suite, but a drop in SLP is still there;

So from what I can take from this morning's model runs is that we have good support for a largely settled and dry weekend and start to next week, if not overly warm. It's then a question of how long the Azores ridge can hold it's ground for. The EC ens are quickest to displace the high back west, the GEFS slower to do so, but even these drop SLP in FI. With the Met Office update and reliability of the EC model better than the GFS (although of course, nothing is inflammable) then my gut instinct tells me to sway more towards the EC outcome. That's the bit the other thread won't like, but it's just my honest thoughts, not hopecasting.

The other thing that has caught my eye, is for a possible build of heights to the north/north east of the UK in the extended timeframe (mid June). Now of course, this is a long way out and could easily change, plus I ain't no expert in long range weather forecasting, but here is why I think this.

A look at the EC mean SLP anomaly shows a notable anomaly over Scandinavia at Day 10;

This also shown by the CFS model (yes, I know lol);

And also present in the 500mb anomaly charts;

Ignore the trough shown on the ECMWF version over the UK for the timebeing, both show a pronounced ridge to the north/north east of the UK, something they have done for a while too.

A quick look at the MJO forecast might explain the differences in the medium to long range forecasts being produced by the various NWP.

The GFS is keen to keep us anchored in phase 1;

which would produce something like this;

which is the broad pattern we can see in the GFS 500mb anomaly chart and FI NWP output. The ECM shows a progression through phase 2 and into phase 3 eventually;

which is why we are seeing a more unsettled FI output by the ECM model, and indeed a trough anchored over the UK by the ECMWF 500mb anomaly chart, as this would produce a more unsettled scenario;

The UKMO somewhere inbetween, hovering around phase 2, which as shown above is still a relatively unsettled pattern;

So possibilities there that if the UKMO model went out further, we would see something more like the ECM output being shown, rather than the GFS.

Any who, keep an eye on both the MJO and the 500mb anomaky charts rather than the ever changing NWP FI output. When these come to an agreement then hopefully the NWP output will start to show something broadly similiar too. My amatuer instinct tells me that the GFS composites will move towards something like the ECM and UKMO, but we will wait and see.

Off out now to enjoy the........ err......... rain! Perhaps we will have some light come the 12 tonight.

[johnholmes]

Another well presented post there AWD, I do hope other folk read it, lots of information there in simple terms which I like. As a believer, with the usual cautions about them then the 500mb anomaly charts will show the way perhaps in 2-3 days, and the MJO is another feature to watch. I am well known for not being over enthusiastic about its predictions though. Usually it is a decent indicator if the orbit is shown some distance from the origin, close to it and it is less use, much like the extended AO and NAO predictions.

They are just my own ideas and as with any one person I am far from fireproof in forecasting!!

Edited May 28, 2013 by johnholmes

[AWD]

The main issue I see with the current NWP output is timing and the eastward extent of the trough that forms in the Atlantic. You can see below that all 3 main models are broadly similiar at 144 hours, all showing a developing, deepening trough to the west of Ireland affecting Ireland and western Scotland at this stage, with Wales and England just about holding on to something more drier and settled;

Whilst this night delay the inevitable for a couple more days, there are a couple of things that aren't the best for further down the line in reference to summer-like weather. I take the UKMO chart for 144 hours for example (all models show broadly the same theme though);

You can see there that whilst the trough continues to deepen in the Atlantic, it pumps up WAA towards Greenland creating weak heights over this area, something known to favour colder conditons for the UK. This also means that the northern arm of the Jet Stream remains slack and instead allows the southern arm of the Jet Stream to intensify more so as shown below by the GFS Op;

Now an intensifying and southerly tracking Jet Stream is something you don't want to see if you want something warm and settled as this will send any LP systems from the Atlantic towards us rather than north of us. Luckily for now there is still time for this to change as the Atlantic looks pretty sluggish to push much in the way of rain fronts across the UK during the reliable and even semi - reliable timeframes due to our block of High Pressure.

A look at the GEFS does show however things slowly becoming cooler with time as any heat and warmth stays south of the Jet and the UK stays on the cooler side to the north of the Jet;

SLP does remain rather slack after the weekend too, suggestive again of the struggle the Atlantic has in getting the trough as a whole over the UK, so instead ejecting energy toward southern England and under the High Pressure;

Again, something I've been saying for a while now. This suggests a sunshine and showers regime rather than a full blown Atlantic attack. A look at the EC ens also show similiar in the rainfall suite;

and more importantly, also agree with the GEFS temperature suite in suggesting a cool down as we go through next week and beyond with temperatures for many of us slightly below average;

This rather more clearer in the boxed version;

So I have a reasonable degree in confidence they after this weekend, temperatures will slow drop away by a few degrees (perhaps with a quick rise and drop midweek next week). and that by the end of next week, slightly below average temperatures are favoured. No heat or above average temperatures are likely for the foreseeable. Not what many want to hear (hence why I posted in this thread). but I don't do optimism, hopecasting or selective picking, I just tell my opinion as it is, honestly and realistically. Hopefully I'm wrong or things change but I don't see different currently.

A weak MJO in the phase 3/4 area isn't helping either;

Until this kicks into life, change will be slow and things will remain rather sluggish. So good support for temperatures to dwindle after this weekend. It's June so even below average temperatures will be pleasent enough in the sunshine, but things do look like cooling down by a few degrees as we progress through next week and more particularly next weekend. The average or very slightly above average temperatures we see this weekend should be made the most of IMO.

However, rainfall doesn't look like nothing too worrying with most of it falling in a showery regime rather than a frontal regime with the exception of Ireland and the far west maybe. This may change but currently there are no signs of a return to the flooding issues we have seen during some recent summers.

[johnholmes]

I'll drop this in here; the latest from NOAA on the ENSO current and predicted state

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.pdf

[johnholmes]

As usual having looked closely every day at the 3 main anomaly charts the overall impression I get from the past 3 days is an upper ridge with +ve heights SW of southern Eire, at times quite close in, and an upper trough east of the UK and perhaps uncomfortably close at times.

This will lead to a surface high off the SW but no real sign of a major upper ridge developing into/over the UK for any length of time. Surface lows skirting around its northern flank giving the most changeable/unsettled weather the further north and perhaps NE you are.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

The Fax chart at T+120 gives a general idea with surface high pressure SW of the country and the 1000-500mb thickness trough (the dashed line roughly NW-SE over the country. Don’t expect it to be like this on any particular day in the 6-15 day time frame, it is just the overall idea of where the surface high is most likely with weather systems running around its northern periphery. So always more changeable in the north and less so the further SW you live. No major heat but pleasantly warm even very warm on some days when the high is in ascendancy.

http://www.weathercharts.org/ukmomslp.htm#t120

[johnholmes]

Maybe amongst all the chat about the synoptic models it is a good idea to see what the longer term drivers are suggesting.

 

If we look at ENSO and I am not even remotely pretending I understand what effect it has on our summer weather patterns. So anyone with such knowledge please put them in-thanks.

The latest output says this

The majority of the model forecasts favour the continuation of ENSO-neutral, with most models

Predicting Niño-3.4 index values below zero (Fig. 6). A smaller number of models (mainly statistical)

predict  weak  La  Niña  conditions  (Niño-3.4  less  than  -0.5°C)  as  soon  as  the  Northern  Hemisphere

Summer. As a result, the forecast consensus indicates larger chances for La Niña relative to El Niño, but

There still remains close to a 60% or greater chance of ENSO-neutral through the Northern Hemisphere

Summer 2013 (see CPC/IRI consensus forecast

 

On to the MJO it currently is in phase 1 which equates to the 500mb pattern shown in the link below

http://www.americanwx.com/raleighwx/MJO/MJO/JunePhase1500mb.gif

In brief a block from se Iceland over the UK down across western Europe and into north Africa.

It appears to be heading towards phase 8 with reasonable amplitude which usually gives a little more credence to the forecast.

Phase 8 is in the link below and I have given both June and July as we are nearing month end.

Phase 8 in June equates to the block still there to some extent but having retreated south east with low values over the Iceland area as well as in the region of the Azores.

For July the picture is as below

http://www.americanwx.com/raleighwx/MJO/MJO/JulyPhase8500mb.gif

Again in brief with the upper ridge having regained some ground north west and also out over Scandinavia.

 

The AO is currently +ve and predicted to edge down with the NAO even more +ve and again predicted to edge down.

 

To the shorter term and the 500mb anomaly charts. All 3 have over the past 3 days suggested some kind of +ve heights, over Europe and Scandinavia with the trough being filled out as the heights rise over Europe. They are not totally alike but are along similar lines in the major pattern idea.

 

Thus the increasing tendency of the synoptic models to show more situations that are similar with surface high pressure shown over or close to the country do have some merit. Discussions as to how warm/hot etc are not for this post as it is simply to give some background to why the 4x and 2x daily synoptic charts are showing this pattern at times.

 

It is still to early to go for this set up but I would think in the 6-15 day time scale then, starting in the south (SE) a more settled pattern is going to develop and probably (60% at the moment but increasing) slowly extend further north. How far is too far ahead but much of the UK away from the far NW should see this development occurring in my view.

 

As always this carries the usual forecast health safety warning.

Copying into the model and more leisurely thread areas

 

John

[johnholmes]

nothing new really in the last 24 hours outputs, the +ve areas continue to be shown but none of the 3 suggest an actual 500mb ridge over/e/se of the UK.

[Dunmurry Hedgehog]

nothing new really in the last 24 hours outputs, the +ve areas continue to be shown but none of the 3 suggest an actual 500mb ridge over/e/se of the UK.

Have been watching for a number of years under a couple of different usernames and can make a reasonable stab at reading 850T, 500hPa and anomalie charts. However I would be grateful if you could give a few tips on reading the 500mb charts. I can understand your your point that if the high pressure to our east is not closed, then the high pressure feature is likely to be transient in nature. However the azores high in the atlantic has been very consistent (albeit ridging closer and pulling away sw on occasion), and often is not shown as a closed loop.Many thanks in advance

[johnholmes]

Have been watching for a number of years under a couple of different usernames and can make a reasonable stab at reading 850T, 500hPa and anomalie charts.However I would be grateful if you could give a few tips on reading the 500mb charts. I can understand your your point that if the high pressure to our east is not closed, then the high pressure feature is likely to be transient in nature. However the azores high in the atlantic has been very consistent (albeit ridging closer and pulling away sw on occasion), and often is not shown as a closed loop.Many thanks in advance

 

I will come back to you tomorrow as pretty occupied overnight to give a considered reply. If I forget please pm me to remind me-thanks

[Thundery wintry showers]

The issue of high pressure being in the "wrong" place was quite well illustrated at my location during the past week which was cloudy on five days out of five, had rain on two of the days and had near or slightly below-average daytime temperatures, though I'm aware that some regions had rather more warmth and sunshine. 

 

This weekend is set to see sunnier and warmer weather extend further north with most of England and Wales affected, and temperatures of around 25-27C may happen in the south tomorrow, but Scotland is set to remain mostly grey.  Monday looks set to be a brighter day in Scotland with scattered showers, not much potential for intense convection though due to the ridging Azores High, while England and Wales should have another dry day with sunny intervals.

http://cdn.nwstatic....2/ukmaxtemp.png

http://cdn.nwstatic....0/42/ukprec.png

 

Between Tuesday and Thursday a low pressure system is set to track further south which will bring a rain belt south-eastwards although most of southern Britain probably won't see much rain from it, and then behind it, the ridging Azores High will most likely prevent any significant showery activity from developing in the polar maritime airstream with most places dry with sunny intervals.

 

After that there are strong hints that pressure will build substantially from the south sending warmer and sunnier weather further north.  Since this build of pressure is forecast for the 7-10 day timeframe I am feeling quite cautious about it, particularly for northern parts of the country, because while current model outputs are generally suggesting a warmer and sunnier spell than many of us have had during the past week, the positioning of the high is still potentially prone to revision.  However, the NOAA 8-14 day outlook does suggestt a fairly significant build of heights at the 500hPa level just off north-western Ireland which is a pretty strong indicator that the high may get further north and east this time:

http://www.cpc.ncep....14day/500mb.php

Going back to John's posts above, I'm seeing more evidence of a potential build of 500hPa heights close to the British Isles than I saw on the past few days' projections.

[johnholmes]

I will come back to you tomorrow as pretty occupied overnight to give a considered reply. If I forget please pm me to remind me-thanks

 

I hope the replies two of us gave have answered your questions? If not please pm me and I will try to help.

[johnholmes]

copied from model thread re the 500mb anomaly charts over the past 5 days or so and what they predict for the 6-15 day period from now

looking at how the 500mb anomaly charts have moved in past week-1 july 2013.pdf

[johnholmes]

A look at how the 500mb anomaly models have changed over the last 4-5 days indicating a change for many after this week.

500mb chart changes Monday 8 july 2013.pdf

[shedhead]

A look at how the 500mb anomaly models have changed over the last 4-5 days indicating a change for many after this week.

500mb chart changes Monday 8 july 2013.pdf

Thanks JH, an excellent informative post. Sad to see so few members appreciating it, simply (in my opinion) because it shows what many don't want to see. Does make you wonder sometimes if this is a forum for genuine weather enthusiasts, or just those who simply crave bitterly cold winters and boiling hot summers.