Model Output Discussion

[snowlover2009]

What i find ironic is in winter the Greenland high can't leave quick enough and yet in summer it hangs around for weeks on end.

The weather has not been too bad over the last couple of weeks, it certainly is not on a par with 2007. It was hot at the beginning of last week and this weekend is looking extremely pleasant.

Going off the models we may get a mixed few weeks with showers, longer spells of rain and dry days all mixed together but no real sustained heat. However i feel as the month goes on and into August the Greenland block will lose its fight and things will begin to shift north.

I still have hopes of a pleasantly warm August.

Don't use the greenland high as an excuse to complain about the Greenland high in summer. Many times in recent winters, the greenland high has stuck around for weeks in winter, not just summer.

[minus 9]

You just cant write july off on the 2nd of the month the models had rain or showers this weekend on countryfile last sunday. Now that has been delayed for 3 or 4 days. This time next week the models could and probably will show something better. Write summer off now no chance!

[Summer Sun]

ECM Shows something better for the south come next weekend and into the following week.

[minus 9]

You just cant write july off on the 2nd of the month the models had rain or showers this weekend on countryfile last sunday. Now that has been delayed for 3 or 4 days. This time next week the models could and probably will show something better. Write summer off now no chance!

[January Snowstorm]

that comment is even further off the mark JS, a good many did predict that-not the intensity but the cold onset and snow was predicted

My memory tells me that many forecasted a cold Winter, but nobody forecast ice days at the end of Nov which is what we got. Indeed it could be further argued that the relatively mild Jan-March wasn't forecast either!!

Anyway back to the models and they aint a pretty picture this morning for the next 10 days or so.

Amazing really the way high's set up situ over us in Winter and yet in Summer you couldn't give your life for one

[Frosty.]

Just had a quick flick through the Ecm 00z and it says everything about this summer so far and in the near future, it's absolute rubbish with low pressure again taking centre stage for the umpteenth time, northern and western britain appear as though they will bear the brunt of the unsettled and often cool conditions but high pressure to the south of the BI will ensure that the best weather on offer will be across southern england with the warmest and driest conditions but really this summer is turning into a non event for the north overall despite the current relatively settled conditions under high pressure but all the talk of a long hot summer has already proved to be very wide of the mark with no sign of a prolonged settled hot spell but august could see a change in fortunes but IMO it will be too little too late by then as the nights will be closing in again.

[IanM]

Final reminder that this area is for model discussion only, some of you seem a little confused. 'It's sunny' 'we need regional' and 'look at the pretty picture I found' are not model discussions. We don't ask a lot and try hard to not over moderate, but this is one forum where I am more than happy to just end posting privileges, think before you post.

[The Northern Ramper]

phase 1 was bad , right?... i dont know how this works but if its in phase 1 now, how soon would it leave and perhaps head to something more favourable? as its the 2nd of july and not august, is it unlikely, impossible, for warmer teleconnections to evolve soon?

as for charts reminiscent of recent julys... maybe on the face of it, and indeed the current gfs fi output is pretty depressing.. but, speaking for my locale, the ground here is still firm and pretty dry, not saturated like in july 07, 08, so im hoping that things wont be as bad.

dont forget either, this current summery spell was first expected to be a day long affair, the ukmo was the first to suggest itll be a longer affair, this evolved out of pretty much nothing, so whilst theres no visible signes of anything settled warm and summery after tuesday, this might well change.

ill not get too depressed just yet, give it another month, if by early august theres no sign of a lengthy settled spell then i think we can call 'game over' in terms of heat. (and please dont go on about how nice september can be... yes it can, but its not summer, the days are shorter, the flowers have finished and the swifts have gone .... summer in september is like snow in march... "if only" )

I know what you are saying, its pleasant when it happens but you know it will be short lived.

It just feels different to previous years to me, its almost as if things have been shunted forward a month compared to previous years. I appreciate there is no science or logic to this but i fancy the pattern to be for a mixed July and then a settled August, akin to a settled September but warmer temps and slightly longer days.

That Greenland high is going to be removed at some point, fortunately for us we have had it early enough to not wreck all of summer and if we lose it for the end of July warm conditions will be allowed to build northwards as the jet stream retreats.

Don't use the greenland high as an excuse to complain about the Greenland high in summer. Many times in recent winters, the greenland high has stuck around for weeks in winter, not just summer.

Two or three weeks like last winter, not six to eight weeks.

[Downpour]

Good post above - and it's perfectly reasonable on the model thread to discuss interpretation of the models, and how this has been dominated by the doom and gloom merchants from the north - more nuanced intepreration please!

[johnholmes]

I don't normally post in Net Wx these days with longer term prospects but this is what I've just posted on my own web site-the 500mb chart referred to in the full version.

Its for the Doncaster area really but gives a fair idea of the weather I think will occur out to the start of the 4th week in July.

No 24 issued 1 July for 13-25 July

Taking a look at the lead up to the actual period and the most reliable guide to me are the 500mb anomaly charts. This especially so when the 3 are showing much the same type of chart and are doing so consistently over several days. That has been the case this week.

The NOAA version below shows their views for the period 9-15 July. It shows a 500mb marked trough over much of the UK with a 500mb flow just north of west and a reasonable speed in the flow into the UK.

Both these suggest that the SE will get the best of any settled weather and even here one has to expect some unsettled weather at times. The further north one lives, and Doncaster is probably nearer to the SE weather type than that in the NW, the more unsettled it will be. Spells of rain or showers, breezy, even windy at times with above average rainfall although not by much. Sunshine levels better in the more sheltered eastern half of the UK, so decent amounts in this area with temperatures about the normal for early July (max=21C min=11C) and rainfall just under normal, rainfall days=1mm or more is about 8 over the whole month.

For the period itself, from 13 July into the start of the 4th week and the longer term signals from ENSO, MJO to me do not really hold out any hope of a major change for most of that period in the upper air pattern shown above. There is a probability, say 30-40%, of more settled weather starting to affect a greater part of the UK rather than the SE by then. This brought about by the Atlantic being fairly quiet with high pressure in relatively southern latitudes, the Azores across into Europe, tending to build rather more than currently. But its not a done thing by any means-see my % probability.

Next update due Fri-Sat 8-9 July

[mushymanrob]

My memory tells me that many forecasted a cold Winter, but nobody forecast ice days at the end of Nov which is what we got. Indeed it could be further argued that the relatively mild Jan-March wasn't forecast either!!

Anyway back to the models and they aint a pretty picture this morning for the next 10 days or so.

Amazing really the way high's set up situ over us in Winter and yet in Summer you couldn't give your life for one

gp predicted a below average december, average jan, above average feb...thats what we got.

I don't normally post in Net Wx these days with longer term prospects but this is what I've just posted on my own web site-the 500mb chart referred to in the full version.

Its for the Doncaster area really but gives a fair idea of the weather I think will occur out to the start of the 4th week in July.

No 24 issued 1 July for 13-25 July

Taking a look at the lead up to the actual period and the most reliable guide to me are the 500mb anomaly charts. This especially so when the 3 are showing much the same type of chart and are doing so consistently over several days. That has been the case this week.

The NOAA version below shows their views for the period 9-15 July. It shows a 500mb marked trough over much of the UK with a 500mb flow just north of west and a reasonable speed in the flow into the UK.

Both these suggest that the SE will get the best of any settled weather and even here one has to expect some unsettled weather at times. The further north one lives, and Doncaster is probably nearer to the SE weather type than that in the NW, the more unsettled it will be. Spells of rain or showers, breezy, even windy at times with above average rainfall although not by much. Sunshine levels better in the more sheltered eastern half of the UK, so decent amounts in this area with temperatures about the normal for early July (max=21C min=11C) and rainfall just under normal, rainfall days=1mm or more is about 8 over the whole month.

For the period itself, from 13 July into the start of the 4th week and the longer term signals from ENSO, MJO to me do not really hold out any hope of a major change for most of that period in the upper air pattern shown above. There is a probability, say 30-40%, of more settled weather starting to affect a greater part of the UK rather than the SE by then. This brought about by the Atlantic being fairly quiet with high pressure in relatively southern latitudes, the Azores across into Europe, tending to build rather more than currently. But its not a done thing by any means-see my % probability.

Next update due Fri-Sat 8-9 July

thanks for that john, even if it doesnt hold out much hope of anything above 'normal'. is your prediction set in stone? or could something different evolve from subtle changes in the teleconnections? obviously i understand that its an interpretation of how things are projected to be, i was just wondering on exactly how accurate the 500mb anomoly charts are..

[johnholmes]

gp predicted a below average december, average jan, above average feb...thats what we got.

thanks for that john, even if it doesnt hold out much hope of anything above 'normal'. is your prediction set in stone? or could something different evolve from subtle changes in the teleconnections? obviously i understand that its an interpretation of how things are projected to be, i was just wondering on exactly how accurate the 500mb anomoly charts are..

set in stone-are you joking mushy, no forecast is ever that!

500mb anomaly charts accuracy

lets say at that time scale I would tend to favour them to either GFS or ECMWF in terms of accuracy, they are all of course doing similar things but I find the 500mb output is more stable' is the word I use and a better guide to the weather type. It has always been easier, prior to computers and since to get the upper levels more accurate than what happens 18,000ft below! But the overall weather type, surface lp's dominating, mobility, or high pressure and lack of mobility does follow relatively easily from the 500mb level in the broader overall pattern.

Beyond the 10-15 day mark then the teleconnections are just as liable at the longer term to be either right or wrong or a bit of both just as any forecast can be.

[mushymanrob]

set in stone-are you joking mushy, no forecast is ever that!

500mb anomaly charts accuracy

lets say at that time scale I would tend to favour them to either GFS or ECMWF in terms of accuracy, they are all of course doing similar things but I find the 500mb output is more stable' is the word I use and a better guide to the weather type. It has always been easier, prior to computers and since to get the upper levels more accurate than what happens 18,000ft below! But the overall weather type, surface lp's dominating, mobility, or high pressure and lack of mobility does follow relatively easily from the 500mb level in the broader overall pattern.

Beyond the 10-15 day mark then the teleconnections are just as liable at the longer term to be either right or wrong or a bit of both just as any forecast can be.

well i admit 'set in stone' was abit rash of me, i should have asked really how accurate they are... i remember about a week ago or so they showed a ridge from the greenland high into europe just to our east... that hasnt transpired (or has it? are the current synoptics what it hinted at?). i guess im a little frustrated at having not much sign of a decent hot spell, i was hoping for one this year dispite the outlook being not too bad overall.

pressure seems a little higher over the near continent mid range, maybe if the wretched greenland high wasnt so strong this next longwave might just retrogress a little allowing some heat to be advected off the near continent, but thats hopecasting.

[Frosty.]

Well after the low pressure domination shown on the Ecm 00z, the Gfs 12z indicates a rise in pressure during next weekend into the start of the following week with a moderately strong ridge covering the uk but only a brief respite before the next batch of bad weather spills in off the atlantic but the coming week shows a fine start and then most of next week turning very unsettled with showers and prolonged spells of rain but also some sunny spells. The outlook remains mixed with no sign of any sustained heat for the BI but maybe if the atlantic becomes more sluggish later in July we will see more impact from the Azores High with the classic transfer of high pressure from southwest to northeast and a big blocking anticyclone setting up home across scandinavia which may salvage something from the wreck of a summer in northern britain but the southern half of england will continue to have a reasonable but very unspectacular summer.

[Gibby]

UKMO tonight looks very unsettled as from Tuesday with our current ridge collapsing as a cold front crosses the UK through Tuesday introducing rain followed by heavy slow moving showers as Low pressure centres over Ireland.

GFS is the same with Low pressure settling near the UK for the middle and end of next week with rain and showers, some heavy for all areas. By Sunday a ridge develops from the SW as Low pressure finally moves away over Scandinavia. For a while thereafter, high pressure lies close to the south with rain more restricted to northern regions while the south has a drier interlude. Towards the end of FI Low pressure develops near the UK once more with a 'back to square 1' type scenario towards the end of the run.

ECM follows the same plan with an unseasonably deep Low off western Scotland later next week. After rain moves across later on Tuesday the remainder of the week sees heavy, thundery showers in rather cool conditions, especially under the rain. By the end of the run there are tentative signs of rising pressure in the south as the Azores high pushes high pressure over France but as shown it s not close enough to exert much influence until 240hrs when a temporary warming takes place with the chance of a plume type scenario in the days that follow.

All the runs show variations on a theme tonight. That theme is unsettled and showery for a number of days through the latter half of next week with some longer spells of sometimes thundery rain too. Both GFS and ECM offer some hope of a break in this setup in 10 days or so with ECM inparticular looking a little steamy on day 10 and no doubt on the days that follow. However, these are just weak signals at the moment and need much support in the ensembles and in the runs to follow.

[rob48]

set in stone-are you joking mushy, no forecast is ever that!

500mb anomaly charts accuracy

lets say at that time scale I would tend to favour them to either GFS or ECMWF in terms of accuracy, they are all of course doing similar things but I find the 500mb output is more stable' is the word I use and a better guide to the weather type. It has always been easier, prior to computers and since to get the upper levels more accurate than what happens 18,000ft below! But the overall weather type, surface lp's dominating, mobility, or high pressure and lack of mobility does follow relatively easily from the 500mb level in the broader overall pattern.

Beyond the 10-15 day mark then the teleconnections are just as liable at the longer term to be either right or wrong or a bit of both just as any forecast can be.

Especially those LRFs

[Weather Boy]

I read this thread so that I can get a better interpretation of the models from people who know more than me, but sometimes I despair.......writing off July on the back of a couple of runs: I ask you!

Yesterday, the GFS had a marvellous summer coming up after a showery blip mid-week. The ECM didn't see it as a blip but a breakdown to something more unsettled for the foreseeable. Now, the GFS looks as if it wants to confine the better weather for the end of next week to the SE quarter, with the ECM agreeing - and even here unsettled weather cannot be ruled out.

So, in the case of the GFS that's a pretty strong turnaround in 24 hours for a prediction that should be towards the end of the time period. Who knows if it will be sticking to the same story tomorrow or Monday?

The point I am making is that to write off a period of weeks on the strength of one day's runs is ridiculous. I also note that people are ignoring the fact that we have a number of days of extremely pleasant weather progged with next weekend's weather on the edge or reliability. But the doom merchants want to look at the possible breakdown and beyond and from there proceed to write off the next 4 weeks!

All we know is fine weather until around Wednesday - rather unsettled after that but for a period of time that is unknown, but with a greater likelihood of more settled weather in the SE than elsewhere.

Edited July 2, 2011 by Weather Boy

[shedhead]

I don't think anyone is writing off July... yet! Clearly there will be some decent spells this month, as there were in June, but the $64,000 question is can we change the pattern to something more condusive to fine, warm and settled weather? To my mind given all we can currently see this will not be easy, but that's not to say it won't happen, however we may need to be very patient.

Edited July 2, 2011 by shedhead

[peterf]

I don't think anyone is writing off July... yet! Clearly there will be some decent spells this month, as there were in June, but the $64,000 question is can we change the pattern to something more condusive to fine, warm and settled weather? To my mind given all we can currently see this will not be easy, but that's not to say it won't happen, however we may need to be very patient.

not all of us want fine settled weather.i'm very happy with the outputs as they are,it's normal growing weather..

[johnholmes]

well i admit 'set in stone' was abit rash of me, i should have asked really how accurate they are... i remember about a week ago or so they showed a ridge from the greenland high into europe just to our east... that hasnt transpired (or has it? are the current synoptics what it hinted at?). i guess im a little frustrated at having not much sign of a decent hot spell, i was hoping for one this year dispite the outlook being not too bad overall.

pressure seems a little higher over the near continent mid range, maybe if the wretched greenland high wasnt so strong this next longwave might just retrogress a little allowing some heat to be advected off the near continent, but thats hopecasting.

I think if you regularly look at the charts I mention for the 7-15 day period, increase your understanding of the relationship between those 500mb contours and what actually happens under those contours then you will tend to be a lot more discriminating when looking at the usual GFS and to a bit less extent the ECMWF charts at that time range.

They are not infallible-nothing is and probably at that time range never will be, but to me over the last 3 years they do on 90% of occasions give a very good and accurate idea of what actually happens at 500mb.

The only way to prove it to yourself, one way or the other mushy, or anyone else interested in fact rather than our very imperfect memories, is to take the ECMWF-GFS and NOAA charts for the 9-15 day period, 00z or 12z and compare them over several months to what the 500mb actual chart looks like, along with a comparison of the synoptic GFS/ECMWF output?

Edited July 2, 2011 by johnholmes

[Jason T]

I read this thread so that I can get a better interpretation of the models from people who know more than me, but sometimes I despair.......writing off July on the back of a couple of runs: I ask you!

Could not agree more, I for one log into this thread for inspiration and to learn. The most frustrating point is that after generally a nice day you read the posts and become slowly depressed and it gets to a point were you cant continue and just log out. Also this jargon of writing off a month based on a daily runs worth of data, is well pathetic. I get the impression that some are looking for that spell of record breaking temps on a roll over, crystal blue skies, severe drought, and the worst storms ever,Well we have had a little taste of that so far around regions

I would like to ask to all what is it that we want output to show, I for one believe the output we have now is much more flexible than what we had 4 weeks ago.

The feedback we must get due to this thread current status must be awfull, Mods if your gonna delete this post due to NOT ON TOPIC,Then to be honest delete the negative post,s first as this is the most positive one yet.

Dare i say lets see what tomorrow brings.

SL

Edited July 2, 2011 by silver line

[snowlover2009]

Two or three weeks like last winter, not six to eight weeks.

Well please make yourself clear in future, if you must know it was a good 5 to 6 weeks from the last week of november to the first week of January that we had a persistent GH and the current greenland high has been disappearing more commonly than recent summers and will return again this week. Anyway back to your first point there is obviously a valid reason as to why Greenland highs are more persistant in summer than winter or it is a coincidence. Anyway why does it matter, we have had some really good winters and months.

Edited July 3, 2011 by snowlover2009

[mushymanrob]

I read this thread so that I can get a better interpretation of the models from people who know more than me, but sometimes I despair.......writing off July on the back of a couple of runs: I ask you!

Yesterday, the GFS had a marvellous summer coming up after a showery blip mid-week. The ECM didn't see it as a blip but a breakdown to something more unsettled for the foreseeable. Now, the GFS looks as if it wants to confine the better weather for the end of next week to the SE quarter, with the ECM agreeing - and even here unsettled weather cannot be ruled out.

So, in the case of the GFS that's a pretty strong turnaround in 24 hours for a prediction that should be towards the end of the time period. Who knows if it will be sticking to the same story tomorrow or Monday?

The point I am making is that to write off a period of weeks on the strength of one day's runs is ridiculous. I also note that people are ignoring the fact that we have a number of days of extremely pleasant weather progged with next weekend's weather on the edge or reliability. But the doom merchants want to look at the possible breakdown and beyond and from there proceed to write off the next 4 weeks!

All we know is fine weather until around Wednesday - rather unsettled after that but for a period of time that is unknown, but with a greater likelihood of more settled weather in the SE than elsewhere.

but the problem is that synoptic charts just down evolve out of nothing, the upstream signals give a good indication as to how the general theme/pattern of weather is most likely to evolve over the next few weeks, and patterns dont often disappear or change abruptly without it first being promoted by the teleconnections. the daily/6 hourly, charts reflect what the upstream teleconnections are suggesting will happen, so writing off a period of time isnt such a daft thing. ive done it before, and been correct. (is i wrote off chances of another big freeze at the end of january because there was no sign of the correct synoptics being in place)

I think if you regularly look at the charts I mention for the 7-15 day period, increase your understanding of the relationship between those 500mb contours and what actually happens under those contours then you will tend to be a lot more discriminating when looking at the usual GFS and to a bit less extent the ECMWF charts at that time range.

They are not infallible-nothing is and probably at that time range never will be, but to me over the last 3 years they do on 90% of occasions give a very good and accurate idea of what actually happens at 500mb.

The only way to prove it to yourself, one way or the other mushy, or anyone else interested in fact rather than our very imperfect memories, is to take the ECMWF-GFS and NOAA charts for the 9-15 day period, 00z or 12z and compare them over several months to what the 500mb actual chart looks like, along with a comparison of the synoptic GFS/ECMWF output?

where do we find these charts john?.. are they on nwx or am i blind?...lol

tentetive signes from the ecm that the southern half of the uk might warm up deep in fi, and the gfs seems to have dropped its idea of a huge northern block, leaving an escape route for this weeks longwave as first suggested by the ecm... in all, a mixed bag again on offer but on the whole pretty average, pleasant at times...

[chionomaniac]

tentetive signes from the ecm that the southern half of the uk might warm up deep in fi, and the gfs seems to have dropped its idea of a huge northern block, leaving an escape route for this weeks longwave as first suggested by the ecm... in all, a mixed bag again on offer but on the whole pretty average, pleasant at times...

Mushy, the tentative signs for improvement with the trough moving northwards are being supported (again tentatively) by the latest MJO forecasts. With tropical convection set to move eastwards this could drag us out of phase 1 and into the more favourable looking phase 2. This could lead to a drier and more pleasant 2nd half of July with just the NW of Scotland being Atlantic influenced. So all eyes on those MJO forecasts for the next few days. I suspect the trough retreating to the north will be the theme for around 10 days time if the MJO is to influence things.

[johnholmes]

hi mushy

the links I use are as below, the first one shows the ECMWF-GFS idea on what the 500mb anomaly charts will look like

http://www.meteo.psu...0z/hgtcomp.html

the second link is into the NOAA weather site for their version

http://www.cpc.ncep....10day/500mb.php

the dotted lines in red or blue indicate what the model is suggesting may be the divergence from the average for the time scale/date in the forecast; red=+ blue=-ve

I tend to use them just once a day although I believe both output 00z and 12z.

Remember that the solid lines are the 500mb 'contours', what the wind flow is predicted to be at 500mb, and in each link, that will show where the major troughs and ridges are predicted to be at the time and date shown, 10 days ahead for the ECMWF-GFS and 6-10 and 8-14 days ahead for NOAA.

On the NOAA link you can also get to other outputs they do, MJO, AO, NAO, PNA etc and the main ENSO output,

this link is the direct one

http://www.cpc.ncep....JO/climwx.shtml

or this

http://www.cpc.ncep.noaa.gov/index.php

just search around there are all manner of links to most of the terms used by GP, ch etc

Remember to learn to walk first though! I'm still learning and read with interest what they both post. There are others on the forum who also show a good grasp of the teleconnections.

Remember also that no matter at what time scale we look the predictions are just that-predictions and just as likely not to be right at times as any other weather prediction. look at them daily, don't jump to conclusions but build up an idea of how they seem to be shaping up over several days to give an idea of how the atmosphere may develop in the time scale they show.

Above all enjoy the learning curve and even more so enjoy what the weather does be that as predicted or not.

Edited July 3, 2011 by johnholmes