Model Output Discussion 30/06/2012

[shedhead]

Certainly more hope in the outputs this morning if fine, dry and warm weather floats yer boat, with ECM showing some sig changes as early as next week and GFS looking considerably more summery come deep FI. Like others I'm also encouraged by the upper air changes that are starting to manifest themselves, but if one thing is encouraging me above anything else its todays lifting of the last few hosepipe bans. I was on the record here as saying when they and the drought orders were introduced it would signal the start of an unprecidented wet spell, now they've finally been lifted I would not be at all surprised to see another volte face to very dry, warm weather. There's not a lot we can rely on in this ever changing world, but Sod's Law is definately one of them...

[nick sussex]

At last some better news from the models especially the ECM which finally starts to ridge the Azores high further ne and lowers those positive heights over Greenland.

The GFS doesn't look as good and the UKMO hard to say as that only goes to 144hrs, much depends on the track of the low at 144hrs which leaves the eastern seaboard of the USA, a ne track will signify at least some change in the jet with less southwards pressure being exerted from those heights over Greenland.

What is agreed on though is the more characteristic summer orientation of the Azores high at 144hrs, once you get that orientated ne/sw and closer then its much easier to at least get some drier interludes.

We'll have to see what the trend is over the next few runs, what has been evident is that the models have tended to edge the pattern further south from their later outputs as they overplayed the weakening of high pressure over Greenland at that time range.

So thats still a concern , but certainly from the ECM thats the best output within 168hrs we've seen for many weeks.

[shedhead]

Agree Nick, encouraging yes, but still a long way from being written in stone. Nice to see you posting in here in what we laughingly call Summer, but it looks as if your part of the world has also not had the best of things so far either.

[Thundery wintry showers]

Indeed, an excellent summary by John. I'm just going to clarify things regarding a question that he raised at the end:

Ps regarding the comment made by Ian (TWS) late last evening and the anomaly charts showing a westerly

once or twice in June. I don’t think so Ian, not looking at my bank of charts for every day through June? Yes a

westerly now and then BUT with the marked upper trough almost always close by the UK. That is the major

difference from this 3 day run-no marked trough close by/over the UK. Its presence was the major reason for

such unsettled weather much more than the westerly flow.

I got the sense of a more westerly type being likely a couple of times during June from extended ECMWF outputs (particularly the operational runs and to a lesser extent the ensemble mean) and also the GFS to a lesser extent. I don't recall the NOAA's 8-14 day projections (which I quite often look at) reflecting this at any stage though, until during the past few days as you suggest.

Regarding the ECMWF run, I agree that there are pointers towards something rather more "summery" but the high would really need to be further north for me to have much confidence in a generally dry sunny interlude away from perhaps the south- I've had many experiences of westerlies on the northern flank of those ridges producing mostly cloudy and breezy weather, albeit drier and warmer in the east relative to what we've been used to recently. The trend is in that direction but I think we'll need to see the trend continue over the next couple of runs or else it may end up a "close but not quite" scenario for many of us, the latter being supported generally by the NOAA 8-14 day anomaly outlook which suggest that the northerly tracking jet will probably, in general, be a stronger "player" than any ridging from the Azores High.

[bringmesunshine]

As a new member am baffled but fascinated by the volume and variety of models out there and not really sure what it all means. But I am encouraged by the general concensus this morning which seems to point to a 'less depressing' outlook for us summer lovers over the next couple of weeks.

Wife keeps asking when the weather will change and I reply 'only when John Holmes suggests tentatively that a pattern change might happen in the 7-10 day timeframe'. She says 'tell John to get a move on then!' So no pressure on, eh John?

[nick sussex]

Agree Nick, encouraging yes, but still a long way from being written in stone. Nice to see you posting in here in what we laughingly call Summer, but it looks as if your part of the world has also not had the best of things so far either.

Thanks, to be honest given your rubbish summer so far I'm not complaining down here,rainfall has been around average, we've had quite alot of dry weather and the odd very hot day, not as much sun as normal but its generally been okay.

You're right to be cautious though given that the models have tried to remove those heights over Greenland in their later outputs before and this has imploded as the output gets into the more reliable timeframe.

I'm slightly more optimistic this time as changes start around the 144hrs mark especially on the ECM output, the jet doesn't look as amplified and the Azores high is edging more into its normal summer position.

[johnholmes]

hi Karl

If I am totally honest I have no real idea. As to the chicken and the egg then most things in meteorology suffer from this problem-which comes first!

I suspect it will take one of the further out teleconnections to cause a major pattern change. Just what that is is very unclear to me. As GP suggested in his summer lrf the prospects for various teleconnections to be more favourable is greater the further we get into official summer. So far, and GP may well correct me, there is not much in the way of signals for that to occur. I am no expert on things beyond about 3 weeks or so ahead.

[Thundery wintry showers]

The MJO phase 3 is quite a good composite for those after high pressure, but the GFS MJO forecasts appear to have it meandering back into phase 2 after having approached phase 3:

http://www.cpc.ncep....O/foregfs.shtml

Phase 2 would also be quite consistent with a westerly type of outlook, although the composites for phase 2 for August are quite anticyclonic, so on the basis of the MJO there might, just might, be a more significant change towards August if the MJO phase hovers around 2 for the next month.

[bluearmy]

Ecm op seems typically over exhuberant. More likely to see a decent ridge crossing the country. Naefs still removing those low anomolys as we head into the last third july but still has us under some for the beginning of the weekend of the 20th. I wonder if any change will accelerate or be delayed. I note heights beginning to rise from the east aswell at that timescale. Remaining 'cautiously optimistic' as the kids school hols begin.

[johnholmes]

As a new member am baffled but fascinated by the volume and variety of models out there and not really sure what it all means. But I am encouraged by the general concensus this morning which seems to point to a 'less depressing' outlook for us summer lovers over the next couple of weeks.

Wife keeps asking when the weather will change and I reply 'only when John Holmes suggests tentatively that a pattern change might happen in the 7-10 day timeframe'. She says 'tell John to get a move on then!' So no pressure on, eh John?

tell her I'll do my best

[shedhead]

Thanks, to be honest given your rubbish summer so far I'm not complaining down here,rainfall has been around average, we've had quite alot of dry weather and the odd very hot day, not as much sun as normal but its generally been okay.

You're right to be cautious though given that the models have tried to remove those heights over Greenland in their later outputs before and this has imploded as the output gets into the more reliable timeframe.

I'm slightly more optimistic this time as changes start around the 144hrs mark especially on the ECM output, the jet doesn't look as amplified and the Azores high is edging more into its normal summer position.

Rubbish Summer so far? Many of us stuck here would argue it's not been anywhere near good enough to qualify as rubbish...

[bringmesunshine]

thanks john, Mrs bms will be waiting with baited breath. My slightly serious point is that there is a lot of really interesting, analytical comment on these posts but also a small amount of mass model posting with little comment or context. Your caution and honesty is refreshing and I've noticed you've hit the nail on the head a couple of times this summer in terms of pattern changes. Whatever happens in the next few weeks you've all kept me interested in this most dismal of summers so far. Keep going everyone, boy will we enjoy it when and if the sun shines.

[swebby]

The MJO phase 3 is quite a good composite for those after high pressure, but the GFS MJO forecasts appear to have it meandering back into phase 2 after having approached phase 3:

http://www.cpc.ncep....O/foregfs.shtml

Phase 2 would also be quite consistent with a westerly type of outlook, although the composites for phase 2 for August are quite anticyclonic, so on the basis of the MJO there might, just might, be a more significant change towards August if the MJO phase hovers around 2 for the next month.

As i mentioned the other day, the GFS forecasts for this have been very bullish about it heading back on itself for the past week or so yet it has kept crawling on to phase 3. Albeit at low amplitude for both the actual and forecast positions.

E.g

I guess with such low amplitude its position is only just discernible anyway. Am i right in thinking that the current sea temps suggest that it should struggle to gain amplitude in phases 3-5?

[Weather Boy]

Some tentative support, IMO, for John's view comes from both ECM and GFS, albeit a long way off. It's important to bear in mind that nobody is talking about high temps and blazing sunshine, or indeed a particularly dry spell. Rather, we have toned down our expectations to such a degree that we are looking for 'normal' summer weather of a bit of rain here and a bit of sun there, rather than constant soakings and this week (if not last) supressed temperatures.

Take this chart from the ECM from next Wednesday:

Heights over Greenland Iceland persist, but the Low approaching is a) not deep and B) has a more 'traditional' north-westerly approach, rather than an approach over the channel or northern France as has been the case recently - so a more westerly regime with the best of the weather in the SE as is commonly the case in summer.

Similarly from the GFS:

Less pronounced heights over Greenland, and ridging attempting in the south, with a agains a more northerly approaching Low compared to what we have been experiencing.

I think there is a build of evidence that we are likely to experience more normal summer weather after next weekend i.e. not that good, but a lot better than we have been having. The possibility of ridging bringing what most people are hoping for remains thereafter, but that is too far ahead to call with any real confidence right now.

[picog]

It has cooled down a bit on the east coast of the US, so if their high pressure was caused by the same events as our low pressure situation, it may be a sign that the weather will settle here too.

[William of Walworth]

I think there is a build of evidence that we are likely to experience more normal summer weather after next weekend i.e. not that good, but a lot better than we have been having. The possibility of ridging bringing what most people are hoping for remains thereafter, but that is too far ahead to call with any real confidence right now.

Good post WB, especially the bit i've bolded, because even relatively more summerlike conditions would represent a real improvment (for summer preferrers) over recent weeks.

I've read John's pdf (informative, thanks) and looked at a few of the recent models and there really does some to be some genuine synoptic genuine support for less constantly wet and unsettled conditions (I'll go no further than that for now!) sometime around next week onwards .... at least the S may benefit from these trends anyway,

Fingers crossed that they get confirmed over coming days output

ETA however : BBC latest four week written forecast is reluctant to be very optimistic at all though ...

Edited July 9, 2012 by William of Walworth

[Scorcher]

The models look far more hopeful to me than they have done for weeks, possibly over a month with ECM showing the Azores High exerting its influence over the South of the country as early as +168h and GFS seems to want to bring this in even earlier. Both models also showing a trend for falling pressure over Greenland although slightly later on- ECM seems more keen for this to happen than GFS however.

[nick sussex]

Both the GFS and UKMO at 144hrs agree on some shift ne of the Azores high, however those positive heights over Greenland remain.

Given the low expectations a change to a more typically unsettled pattern with at least some occasional ridging ne of the Azores high would at least give the odd drier day.

We'll have to see what trend develops now regarding how far northeast the Azores high ridges, it might turn out that southern and central areas of the UK do best with the most unsettled conditions being in northern areas.

Looking at the GEFS maps for 168hrs, good support for the Azores high edging ne'wards but although heights over Greenland drop a little the jet is still further south than should be expected at this time of the year.

Edited July 9, 2012 by nick sussex

[bluearmy]

Very good mean jet for the end of gefs 12z. Pointing sw to ne across the atlantic towards nw scotland. Finally !!

Edited July 9, 2012 by bluearmy

[phil nw.]

Very good mean jet for the end of gefs 12z. Pointing sw to ne across the atlantic towards nw scotland. Finally !!

Would like to see more runs yet Nick.

It looks like that next week this westerly pattern we talked about earlier today will come about but there`s a fair amount of spread in where the mean jet will go.

There are differing forecasts for the MJO in the next 15days both in amplitude and placement and i think this uncertainty will reflect in the model runs for now.

Before then the outputs have that AH oscillating back and forth across the Atlantic and we have a lot of unsettled weather to get through first.

Edited July 9, 2012 by phil n.warks.

[Jonathan Lang]

Looks a bit warm and nice by end of 12z GFS!

[Cloud 10]

10 day NAEFS 12z paints a grim but familiar picture of the trough still sat over the UK.

Still some of those "green shoots" of summer showing up towards the end of the run

with pressure rising over the continent.

[bluearmy]

10 day NAEFS 12z paints a grim but familiar picture of the trough still sat over the UK.

Still some of those "green shoots" of summer showing up towards the end of the run

with pressure rising over the continent.

indeed, a trough rolling over the transient azores ridging seems likely for the latter part of next week. however, the rise in heights to our east beyond that is significant. the higher heights around greenland seem destined to hang on. as JH has pointed out, a westerly regime seems likely for the atlantic as the greeny high anomoly becomes detatched from the azores high which removes the amplification in the jet which has spawned so many shortwaves over the past months. rather than the jet crashing on through just to the south of the uk, it will have to head ne to our west as the rising sceuro high getting much closer to the uk than previously this season deflects it that way. i think hopes that the azores ridge will be our saviour are unlikely without the support of the sceuro block. the azores ridge has shown itself incapable of holding itself into nw europe at all for many months. if the ecm 32 dayer follows this script tomorrow morning then expect quite a different tone to the meto 30 day forecast tomorrow lunchtime.

[Robbie Garrett]

I haven't really looked at the Models, but for any settled weather we really need to have a NAO state of that of early March or at the very least mid-late March.

Just look at how it's gone downhill ever since. Everytime it looks to go neutral, it really does seem to head back into a more negative state, even worse than the previous.....

[Buzzit]

The GFS18z OP run continues its FI trend towards more settled weather. If it pans out I will have to start playing "I'm a Believer" on high rotation haha