Model Output Discussion 18z 28/07/13

[mushymanrob]

*lets out a short sharp expletive*

 

why oh why do we never learn?... what was looking like a protracted spell of warm/hot sunny dry weather has all but evaporated. gone is the 15c upper that was progged so often by so many runs. all these 'fantastic' and 'epic' runs have all now downgraded to a couple of nice warm days (thurs fri). 

 

the gfs might have done a u turn on the 00z, and refuses to develop saturdays shortwave, keeping it to our south, leaving us with warm uppers and high pressure to our near north

 

.... but then the ecm has also done a u turn (12z) and agrees with what yesterdays gfs runs predicted and the ukmo appears to be heading the same way... developing that shortwave, tracking it up and over us, then introducing the atlantic back afterwards...ok another pressure rise is possible next week as the azh could ridge in... but we would be a long way from anything very warm/hot.

 

so great uncertainty from saturday onwards, chances of a lengthy settled warm spell have receeded but are not dead, chances of the warmth being a 2-3 day wonder and a return to more average conditions have increased...

 

maybe the anomaly charts shouldnt have been ignored by us (most of us), the 'big 3' did not, do not, agree over 3 runs in a way that would clearly support a protracted hot spell in the way most op runs depicted.

[bluearmy]

although not yet supported, this mornings gem op pretty well dispenses with the trough as a meaningful feature. Not the favoured option by a long way but its 'on the table'. Gfs again makes a meal out of the trough, especially for the south of the uk. Ecm and ukmo not looking very similar re heights over the uk at day 6 which is a sure sign that things remain too uncertain to make an informed call. Rob seems to be quite depressed by the whole thing, judging by his last post. I wouldnt be throwing the towel in on an extended spell of good weather just yet rob. Even if the trough does bring a short spell of less pleasant stuff, if either side is a useable week, thats not too bad - is it?

[Severe Siberian icy blast]

*lets out a short sharp expletive*

 

why oh why do we never learn?... what was looking like a protracted spell of warm/hot sunny dry weather has all but evaporated. gone is the 15c upper that was progged so often by so many runs. all these 'fantastic' and 'epic' runs have all now downgraded to a couple of nice warm days (thurs fri). 

 

the gfs might have done a u turn on the 00z, and refuses to develop saturdays shortwave, keeping it to our south, leaving us with warm uppers and high pressure to our near north

Rtavn1502.pngRtavn1802.png

 

.... but then the ecm has also done a u turn (12z) and agrees with what yesterdays gfs runs predicted and the ukmo appears to be heading the same way... developing that shortwave, tracking it up and over us, then introducing the atlantic back afterwards...ok another pressure rise is possible next week as the azh could ridge in... but we would be a long way from anything very warm/hot.

Recm1442.gifRecm1922.gif

 

so great uncertainty from saturday onwards, chances of a lengthy settled warm spell have receeded but are not dead, chances of the warmth being a 2-3 day wonder and a return to more average conditions have increased...

 

maybe the anomaly charts shouldnt have been ignored by us (most of us), the 'big 3' did not, do not, agree over 3 runs in a way that would clearly support a protracted hot spell in the way most op runs depicted.

Morning mushy .

To be honest with you not everyone has been talking up this weeks weather , only a handful of members posting lots of charts in deep fi and talking it up like it was a dead cert , where in reality , it has never been on 500mb charts for any length of time , nothing has been consistent on them , so until it was ,then any prolonged hot spell was unlikely , which is why it's really misleading when some posters do what they do .

I say hats of to John H for really sticking to his professionalism as his techniques really work . It's his experience we need to look to on hear if its a forecast rather than a hopecast we seek.

So all in all a nice warm week to come with sunshine and light winds , but breaking on the bank hol . That doesn't mean a complete washout , it proberbly means unsettled at times , but no doubt stil rather warm , and sunny at times , which isn't a bad outlook. But this week its a 3-4 day surface high pressure spell which will be nice . But it's not a long hot and sunny spell going into September like a post I read last week .

[mushymanrob]

Morning mushy .To be honest with you not everyone has been talking up this weeks weather , only a handful of members posting lots of charts in deep fi and talking it up like it was a dead cert , where in reality , it has never been on 500mb charts for any length of time , nothing has been consistent on them , so until it was ,then any prolonged hot spell was unlikely , which is why it's really misleading when some posters do what they do .I say hats of to John H for really sticking to his professionalism as his techniques really work . It's his experience we need to look to on hear if its a forecast rather than a hopecast we seek.So all in all a nice warm week to come with sunshine and light winds , but breaking on the bank hol . That doesn't mean a complete washout , it proberbly means unsettled at times , but no doubt stil rather warm , and sunny at times , which isn't a bad outlook. But this week its a 3-4 day surface high pressure spell which will be nice . But it's not a long hot and sunny spell going into September like a post I read last week .

 

morning!

 

agreed, but tbh posters were only posting successive chats that all pointed in one direction. they would have been misleading IF they cherry picked favourable charts, but the ops have consistently suggested a protracted hot spell,  so believing they would happen wasnt misleading imho.

[Frosty.]

I'm happy with the GEFS 00z mean this morning, it shows the PFJ (polar front jet) looping across approximately from canada, southern greenland across to iceland and northern norway right the way through to early september, indeed the mean shows no sign of the PFJ sinking towards the uk, the azores/atlantic anticyclone continues to ridge towards the uk and extends at least a weak ridge across the BI through most of FI.

 

This week it's going to warm up, especially across the south of the uk with temperatures generally around 24c 75f through to midweek and the next few days will bring increasing amounts of sunshine to the south, however, wednesday looks generally cloudier but it will be warm, the northwest corner of the uk will have a spell of rain and breezier conditions midweek but then settling down for a few days as high pressure continues to build and gradually becoming centred to the east, enabling a continental very warm and sultry SE'ly airflow to drift up across the southern half of the uk for thursday & friday, this is when temperatures will soar, high 20's celsius, low to mid 80's F, especially for southern/se england and east anglia, perhaps nudging to 30c 86f  and with lots of strong scorching late august sunshine which will gradually become more hazy with time, away from the south and southeast, it will also be much warmer on thurs/fri with temps into the mid 20's celsius range, something like 26-27c 80f for many areas but closer to mid 70's F for n.ireland & scotland because there are likely to be heavy showers breaking out across the north towards the end of this week and more generally across the uk by the bank holiiday weekend because our anticyclone will have drifted further east with a weakness ( shallow trough) also edging northeast and with the high pressure leaking away and with a pool of very warm and sultry air in situ, heavy and thundery showers becoming widespread during the weekend into the start of next week but then during next week we could see the azores/atlantic anticyclone ridging in again, it would mean a transition with cooler, fresher atlantic air mixing out the warm/humid showery air but then it would probably at least become pleasantly warm again with temps in the low 20's celsius later next week.

Edited August 19, 2013 by Frosty039

[shedhead]

The much vaunted heatwave, hot spell, lengthy fine, warm spell call it what you will, looks even farther away than ever this morning, with ECM in particular painting a cool picture for next week. 

 

GFS, whilst not quite so bad paints a pretty similar picture, with winds coming in from a cooler NW direction by then.

 

 

Until that time it's a story of pretty average conditions this week across much of Scotland and N Ireland, with temps peaking aound 19-23c for most on Fri/Sat.  England and Wales still look set to see a steady warm up as the week unfolds, but for most maxima in the range 22-26c should cover it, with only favoured parts of the E and SE seeing values above 27-28c. The weekend promises some rain or showers for all, with the south being at greatest risk from some heavy, thundery outbreaks, then as we go into BH Monday the irony according to GFS is some of the best weather on offer will be across the one part of the country that does not have a BH. You couldn't make it up really..

 

 

ECM of course says NO tho...

Edited August 19, 2013 by shedhead

[johnholmes]

The honest comment about the anomaly charts has to be that they have not been totally consistent not to me all that good in overall guidance for the BH weekend. Remember that they are for the 6-10 day time scale or even further 8-14 so anything over the last couple of days is already really beyond that. If we take an 'average', say for the Sunday=25 August, what did they show?

They have not given a consistent signal for the BH weekend other than all 3 showing some kind of upper ridge and +ve heights then fairly late on starting to show some troughing in the area NW of Iberia and then cut off lows. The degree of confidence (or lack of) in their output is to some extent mirrored by the changes seen in the Met O output.

Their inconsistency is also shown by the changes in the synoptic models. Have a look at how much they have changed over a 2-3 day period.

The overall idea of some kind of breakdown over the BH weekend from the relatively settled spell that develops through this week has been fairly well indicated but the detail is still far from clear.

If you look at the link below for beyond the BH weekend on the ECMWF-GFS morning output, continuity, what’s that? ECMWF shows a pattern that would have cold lovers drooling in mid winter, from a previous set of charts that look nothing like it. As to whether this is a change in pattern or a blip-watch this space over the next 2-3 days!

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

 

To be fair to them they did indicate 10-14 days ahead the change from fairly mobile westerly type to a more blocked pattern as we are going to see with much of this week.

Edited August 19, 2013 by johnholmes

[Tamara]

morning!

 

agreed, but tbh posters were only posting successive chats that all pointed in one direction. they would have been misleading IF they cherry picked favourable charts, but the ops have consistently suggested a protracted hot spell,  so believing they would happen wasnt misleading imho.

A protracted hot spell has not really been suggested and interruptions always possible. Nothing has really changed in that respect

 

I think best that people don't jump because the computer models appear to jump Extra uncertainty atm and a typically non straightforward Bank Holiday to come. But best that anything beyond the approach of that trough is taken with a large pinch of salt atm. Fwiw - the UKMO looks the most likely and continues to make less of a meal of the trough itself. Have a good day all - its shaping up well in the sunshine

 

Cut-off lows between two areas of high pressure are always badly modelled. This type of synoptic has been shown time and again and is never certain till right up to the day or so itself. It could be a long week in that respect  All the more reason to stick with what we have (excepting of course some north western areas that have the midweek rain of course)

Edited August 19, 2013 by Tamara Road

[TonyH]

Why this fashion for 'short wave' what's wrong with saying 'low' ?

Edited August 19, 2013 by TonyH

[Man With Beard]

The honest comment about the anomaly charts has to be that they have not been totally consistent not to me all that good in overall guidance for the BH weekend. Remember that they are for the 6-10 day time scale or even further 8-14 so anything over the last couple of days is already really beyond that. If we take an 'average', say for the Sunday=25 August, what did they show?

They have not given a consistent signal for the BH weekend other than all 3 showing some kind of upper ridge and +ve heights then fairly late on starting to show some troughing in the area NW of Iberia and then cut off lows. The degree of confidence (or lack of) in their output is to some extent mirrored by the changes seen in the Met O output.

Their inconsistency is also shown by the changes in the synoptic models. Have a look at how much they have changed over a 2-3 day period.

The overall idea of some kind of breakdown over the BH weekend from the relatively settled spell that develops through this week has been fairly well indicated but the detail is still far from clear.

If you look at the link below for beyond the BH weekend on the ECMWF-GFS morning output, continuity, what’s that? ECMWF shows a pattern that would have cold lovers drooling in mid winter, from a previous set of charts that look nothing like it. As to whether this is a change in pattern or a blip-watch this space over the next 2-3 days!

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

 

To be fair to them they did indicate 10-14 days ahead the change from fairly mobile westerly type to a more blocked pattern as we are going to see with much of this week.

Thanks John for continually highlighting the lack of certainty in a prolonged hot spell. Kept many feet on the ground.

 

The models haven't done that badly really - have to admit I was one of the sceptics of the deepening shortwaves for this week - looks like I will be wrong this time as the first one for mid-week was progg'd correctly by ECM - still a long way to go until Saturday's SW, though.

 

Worth remembering that a 5/6 day settled spell (as it will be in the south) is still pretty good for a UK summer, perhaps July's heatwave has shifted some expectations.

[johnholmes]

Why this fashion for 'short wave' what's wrong with saying 'low' .

here very much here

it sounds technical 

[Methuselah]

A protracted hot spell has not really been suggested and interruptions always possible. Nothing has really changed in that respect

 

I think best that people don't jump because the computer models appear to jump Extra uncertainty atm and a typically non straightforward Bank Holiday to come. But best that anything beyond the approach of that trough is taken with a large pinch of salt atm. Fwiw - the UKMO looks the most likely and continues to make less of a meal of the trough itself. Have a good day all - its shaping up well in the sunshine

 

Cut-off lows between two areas of high pressure are always badly modelled. This type of synoptic has been shown time and again and is never certain till right up to the day or so itself. It could be a long week in that respect  All the more reason to stick with what we have (excepting of course some north western areas that have the midweek rain of course)

Well said, Tamara. 100% agree!

[Cecil Hogmanay Melchett]

Well is looks mainly dry sunny and warm in the reliable timeframe.Suggestions from ecm and gfs that things my go downhill as head towards the weekend with that system in the Atlantic complicating matters but im sure there will be twists and turns to come in that regard.

Another lovely week for many to cap off a gorgeous summer.

I'll take another summer 2013 with open arms next year thankyou very muchly!!

here very much here

it sounds technical 

John you have been excellent in recent times with level headed and accurate posting when some of us were getting a bit carried away with the charts of last week.

Well done sir!

[snowking]

The longer range model outputs this morning look to be reacting to a phase 1 MJO signal, and whether you look at such a signal for either August or September, the result looks the same:

 

 

 

Still a lot of uncertainty in both operational and ensemble outputs at the moment, but a lengthy heatwave such as that experienced through July hasn't really looked odds on if you had stuck to using ensemble means and of course the now famous anomaly charts. However, beyond a few blips a mostly settled end to August does look on the cards the further South you head across the UK.

 

SK

[Captain Shortwave]

The honest comment about the anomaly charts has to be that they have not been totally consistent not to me all that good in overall guidance for the BH weekend. Remember that they are for the 6-10 day time scale or even further 8-14 so anything over the last couple of days is already really beyond that. If we take an 'average', say for the Sunday=25 August, what did they show?

They have not given a consistent signal for the BH weekend other than all 3 showing some kind of upper ridge and +ve heights then fairly late on starting to show some troughing in the area NW of Iberia and then cut off lows. The degree of confidence (or lack of) in their output is to some extent mirrored by the changes seen in the Met O output.

Their inconsistency is also shown by the changes in the synoptic models. Have a look at how much they have changed over a 2-3 day period.

The overall idea of some kind of breakdown over the BH weekend from the relatively settled spell that develops through this week has been fairly well indicated but the detail is still far from clear.

If you look at the link below for beyond the BH weekend on the ECMWF-GFS morning output, continuity, what’s that? ECMWF shows a pattern that would have cold lovers drooling in mid winter, from a previous set of charts that look nothing like it. As to whether this is a change in pattern or a blip-watch this space over the next 2-3 days!

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

 

To be fair to them they did indicate 10-14 days ahead the change from fairly mobile westerly type to a more blocked pattern as we are going to see with much of this week.

Fair play, perhaps a lesson in future to perhaps be a little more grounded in our expectations, I know I will. After all, many of us on here are amateur enthusiasts rather than have vast knowledge and experience like yourself.

Still we would have got away with it if it wasn't for those meddling shortwaves

Edited August 19, 2013 by Captain shortwave

[Frosty.]

The Ecm 00z ensemble mean shows a very warm and sultry spell for at least the southern third of the uk later this week, thurs/fri look very warm or hot with temps of 27-30 celsius, 81-86F, further north & west, also very much on the warm side at around 24-26 celsius, 75-79F. The next few days look progressively sunnier and warmer, up to 24c 75F, wednesday will be cloudier but warm and a period of rain and breezier for the northwest corner of the uk then fine and warm for a few days. This run shows high pressure holding a while longer to the northeast but still shows a shallow trough (weakness) pushing in by the weekend, so a very warm and humid weekend with hazy sunshine and thundery showers with torrential downpours but hit and miss although probably more hit than miss, temperatures slowly sliding down to average early next week and remaining showery but the azores/atlantic anticyclone continues to ridge towards the uk and during next week it could begin to build in once again, the best news of all is the PFJ remaining well to the north of the BI into early september, actually, the Gefs & Ecm 00z mean look very similar.

[Captain Shortwave]

I know it's probably more in hope than anything else but the 06z GFS looks a lot better for the bank holiday weekend

 

 

Saturday would be very warm if this came off. would also be dry apart from some showers in the west.

 

Potential thundery activity for the SW, Wales and Ireland on Sunday

Ok GFS, you are just teasing us now 

Edited August 19, 2013 by Captain shortwave

[Man With Beard]

A hot weekend on GFS 06Z - this chart for Sunday has the low moving into to SW but no further - possibility of dry days on Sat/Sun apart from a thunderstorm or two. Encouraging to see GFS going this way as it has been the least settled up till now.

 

 

[Cecil Hogmanay Melchett]

Well this week looks mainly dry and warm for the majority but as we approach the weekend all confidence drains away rapidly as the models continue to struggle with the behaviour of this low pressure system moving in off the Atlantic.

06z wants to push it towards the SW of England and then move it northwards and stall it somewhere around Ireland.

Not sure thats the end of this little saga!

[East_England_Stormchaser91]

Ok back to better potential for some warmth and decent storms on the 06z. GFS, make your flaming mind up! Swear it has bipolar sometimes!

[A.J]

yep, much better run in the medium term.....Low pressure remains anchored in the south west approaches (I say low pressure because IMO it has a closed circulation and thus shouldn't be described as a shortwave,more of a cut off low pressure system)...so the warm air advection continues from the continent allowing temps & humidity to soar....

 

there'll be a thundery threat as the SLP charts show a complex low with plenty of troughs in the circulation over southern parts of the UK as we move though the latter part of the weekend as we gradually lose the continental feed as we move into the new week allowing a cooler northwesterly flow with LP affecting the northern UK as we move into FI whilst the south and and especially the southwest looks fairly benign under the influence of ridging of the Azores High...

 

so with a southern bias my summary is increasing warmth and humidity as we move through this week, with an increased threat of thundery rain/thunderstorms as we move into the weekend, more especially on sunday.......this is of course, based on the 06z GFS, so expect some changes along th way!

[Buzzit]

Model output is a bit of a dogs breakfast at the moment (to put it mildly)

To my mind we are in a take each day as it comes pattern at the moment so not point looking into FI for now... which I currently have as +66

Enjoy the mania if you are watching the wild run to run swings but please keep accusations against other members posts off the thread as there is bound to be wild variation over the next couple of weeks with nobody having any good idea of where we will be come 1st September

[forecaster]

 

This goes some way to explaining why the 850hPa temperatures are not extremely warm on Friday. The air originates around 700hPa at 55N today. The temperature there is -2C. +15C of warming by dry adiabatic descent and you have the resulting +13C 850hPa temperatures expected on Friday. This is not a long draw continental feed, even at the surface. It's modified mid/high latitude maritime air.

[bradymk]

Hopefully this afternoons runs will build on the GFS 6z. As many have said above, it is a much better run keeping it much warmer and drier for longer this weekend and even shows possibility for 27c for the south east as far away as Monday. The LP stays further south west, plenty of time for it to continue the trend of moving Sw'wards, however we all know plenty of time for it to trend back in the opposite direction. Also, hopefully ECM ditches its FI, big northerly which would not be the end to August most would like, brrr.

[Frosty.]

The Gfs 06z op run in high res up to T+192 hours is SPECTACULAR  wow,BANK BANK this run, it shows a heatwave on the way later this week and through the bank holiday weekend into early next week, those who are writing this warm spell off as a non event, don't be surprised if this type of run gains support, as things stand, even without this stonker, things are looking pretty damn good anyway with a significant warm up for the south of the uk and a warm spell for all, it will feel very summery again and for storm enthusiasts, yes there is a risk of storms and heavy showers this weekend and early next week but the 6z delays it and brings a cracker of a weekend with just isolated storms across the west and southwest and a few thundery outbreaks through the weekend but with a lot of hot and hazy sunshine and very sultry, you won't find the 564 dam line getting so far north very often.

Edited August 19, 2013 by Frosty039