Model Output Discussion 22/07/12 Onwards.

[Thundery wintry showers]

Negative posts complaining of a "meh" type of outlook are guilty of either downplaying the current outlook, or trying to speak for everyone regarding preferences (i.e. anything less than sustained high pressure being a disappointment). Today's outputs are a world apart from what we saw during the first half of the summer, and the synoptic setup progged for the weekend onwards is reminding me a lot of the Julys of 1994 and 1995, with southerly tracking depressions held out in the Atlantic and high pressure to the NE with frequent southerly winds over the British Isles.

It is possible that the models may be underestimating the jet stream and that we might see the Atlantic trough shifted further east promoting a cooler, cloudier, changeable type of outlook, but over the last few days the outlook has shifted from "cyclonic with a slight southerly bias" towards "strongly southerly".

As for the upcoming anticyclonic interlude, there will be a fair amount of cloud in the S and SW of England tomorrow, slowly retreating westwards, and a scattering of showers mixed with sunshine further north, but by Thursday it looks to me as if showers will be very isolated while frontal cloud will retreat to Ireland leaving Scotland, Wales and England with skies varying from clear to partly cloudy. The thundery breakdown for the weekend is still "on" for the south-western third of Britain on Sunday, but has been delayed until Monday further north and east. However, I concede that it won't be warm and sunny everywhere, with eastern Scotland likely to see some low cloud off the North Sea.

[BLAST FROM THE PAST]

Looking at the charts there seems to be a trend to build presuure to our NE. As the trough tries to move in I think what will begin to show is the pressure remaining strong to NE establishing acros to Iceland and LP getting sent into France. I think a pattern of drier/warmer weather is emerging latter half of Aug. I hope it goes that way. Concern is trough moves across UK but there are signs HP remains strong and we may see a -ve tilt develop.

BFTP

[SP1986]

The 0z shows this to be true with cooler unsettled conditions after the main ridge of high pressure. There will be a differential between the warm and cool airmasses so there could be alot of heavy rain into the middle part if the month. On the whole, warm sunny weather will be fairly short lived (in any great quantities) away from

the south so we have this short window of opportunity. Regarding storms - well I haven't heard thunder once this year and I am convinced this year at least here will be the first year without having any thundery activity to report!

[Evening thunder]

It seems after the models shifted everything west yesterday evening, they have now shifted everything east with us more changeable although affected by some southerly plumes briefly on some models e.g the ECM. You can see that as many (but not all oddly enough) of the charts in my post above have changed so my last post may not make so much sense now!

A couple seem to find a way to get us back more under the trough, i.e the high in Scandinavia shifting west towards Greenland and the Atlantic trough shifting east over us. The GEM and to an extent the ECM do this. I hope that doesn't become a trend but it is in FI and the models are changing around quite a bit, although that is to be expected to some extent into FI of course.

Alternatively.. who knows, maybe last night's charts could be more correct and this mornings charts a wobble, it's funny how some always seem to think unsettled charts will happen as soon as they appear but don't take account of/ignore runs that have suggested differently until it looks certain of course.

Edited August 8, 2012 by Stormmad26

[shedhead]

The 0z shows this to be true with cooler unsettled conditions after the main ridge of high pressure. There will be a differential between the warm and cool airmasses so there could be alot of heavy rain into the middle part if the month. On the whole, warm sunny weather will be fairly short lived (in any great quantities) away from

the south so we have this short window of opportunity. Regarding storms - well I haven't heard thunder once this year and I am convinced this year at least here will be the first year without having any thundery activity to report!

Agreed Stephen - something of a short, sharp reality check this morning for those expecting the upcoming 'blip' to develop into a spell, indeed IF the 06GFS verifies we are heading back towards June type rainfall.... this looks very wet indeed.

[SP1986]

Alternatively.. who knows, maybe last night's charts could be more correct and this mornings charts a wobble, it's funny how some always seem to think unsettled charts will happen as soon as they appear but don't take account of/ignore runs that have suggested differently until it looks certain of course.

I can understand where you are coming from but this isnt entirely true because this year the times where extended high pressure has been predicted after a short spell it just hasn't materialised, and instead unsettled cool conditions have dominated - for example the end of May and June. The overall pattern has not changed so to expect a future with frequent high pressure is perhaps too optimistic given the current situation. So actually those jumping on the unsettled conditions have actually been more accurate, when the models finally jump onto it.

[Methuselah]

I can understand where you are coming from but this isnt entirely true because this year the times where extended high pressure has been predicted after a short spell it just hasn't materialised, and instead unsettled cool conditions have dominated - for example the end of May and June. The overall pattern has not changed so to expect a future with frequent high pressure is perhaps too optimistic given the current situation. So actually those jumping on the unsettled conditions have actually been more accurate, when the models finally jump onto it.

True Ste, but patterns do change. So I'll be looking forward to the 06Z with more than my usual degree of interest...And, anyway, wouldn't unsettled and warm still constitute a change in pattern - however slight it may appear on paper?

[Evening thunder]

I can understand where you are coming from but this isnt entirely true because this year the times where extended high pressure has been predicted after a short spell it just hasn't materialised, and instead unsettled cool conditions have dominated - for example the end of May and June. The overall pattern has not changed so to expect a future with frequent high pressure is perhaps too optimistic given the current situation. So actually those jumping on the unsettled conditions have actually been more accurate, when the models finally jump onto it.

That is a point I guess, I do have that feeling that once again it may be the more unsettled charts that come off, given recent occurrences, although I was just trying to think objectively but maybe was being a bit optimistic. Thinking about it that way I can understand to some extent why some jump on unsettled charts quicker, though alternative ones shouldn't be completely dismissed IMO. Although I would be happy with a warm flow even if there are a few intervals of more unsettled weather (especially if convective/thundery), whereas some may only want high pressure over us to give warm/hot and dry.

The 06z shifts the low west a bit again with plenty of average-above average temps into next week though of course not completely settled, as ever time will tell what happens.

[SP1986]

Well if we look at the last two weeks it actually has not been too bad.. The synoptics defy a fairly average summery scenario, so this has a lot to do with the jetstream which has moved north. The foreseeable future looks pretty average in terms of temperature albeit mybe a bit wet and thundery in some parts in the mid time frame as it currently stands... It's not too bad...

That said, the GFS is most likely vastly underestimating the potential of home grown heat..

[SP1986]

True Ste, but patterns do change. So I'll be looking forward to the 06Z with more than my usual degree of interest...And, anyway, wouldn't unsettled and warm still constitute a change in pattern - however slight it may appear on paper?

When I think of patterns I always envisage cycles within cycles, in a self contained system if you like. Therefore a general pattern containing a smaller cycle pattern containing smaller cycle patterns... i believe the smaller ones have changed but the overall general pattern hasnt changed.. (in my opinion?)

[Frosty.]

The models are indicating a bit of a mexican standoff next week with scandi high pressure and low pressure out west with the uk in a warm but changeable flow mainly from the south, the gfs 6z shows an unsettled blip in the south of the uk on sunday but the north drier until early next week, temps look good in the coming days, generally 23-25c but higher in places depending on amounts of sunshine. Next week warm or very warm at times in the southeast with the best weather in the southeast quarter of the uk but more unsettled in the north and west at times but temps look higher than average in most of the uk during the next 7-10 days. The period from now until saturday will be increasingly anticyclonic but sunshine amounts variable.

Edited August 8, 2012 by Frosty039

[johnholmes]

When I think of patterns I always envisage cycles within cycles, in a self contained system if you like. Therefore a general pattern containing a smaller cycle pattern containing smaller cycle patterns... i believe the smaller ones have changed but the overall general pattern hasnt changed.. (in my opinion?)

It depends what you mean Stephen? There have been at least 2 pattern changes this summer, blocked type to westerly. The idea you suggest of smaller cycles within larger ones is a fairly sound idea though.

[johnholmes]

That is a point I guess, I do have that feeling that once again it may be the more unsettled charts that come off, given recent occurrences, although I was just trying to think objectively but maybe was being a bit optimistic. Thinking about it that way I can understand to some extent why some jump on unsettled charts quicker, though alternative ones shouldn't be completely dismissed IMO. Although I would be happy with a warm flow even if there are a few intervals of more unsettled weather (especially if convective/thundery), whereas some may only want high pressure over us to give warm/hot and dry.

The 06z shifts the low west a bit again with plenty of average-above average temps into next week though of course not completely settled, as ever time will tell what happens.

Frequency of occurrence of unsettled weather in the UK would tend to give unsettled weather patterns more chance of verfying than the settled anticyclonic type I would suggest?

[Summer Sun]

Not a bad 12z run from GFS we've certainly had worse August's over the past years, this one could turn into one of the best for a number of years

[jonathon]

not warm at night though. been going though the charts this week and they look quite green come next week at nights so it could get quite chilly at night. just thought i point that out. mods sorry if i gone of topic. europe looks set to cool right down at night in fact. i think the high pressege for next week will go and it could not saying it will get quite wet and windy but as ever charts will change and so on.

[phil nw.]

It looks quite likely that the dry and warm conditions now extending nationwide could hang on around the Olympic Park until events close on Sunday.

The trough out in the Atlantic moves in slowly into western areas over the weekend but any rain further east will be light and patchy arriving late on Sunday and into Monday.

In the meantime some sunny warm weather is the main theme for the next 3 days apart maybe from the north east coasts and late on Saturday in the far west as the first of the fronts approach.

It does like rain will affect most areas at times into early next week as we see that Atlantic trough edging a little closer as the days go on.

Here the UKMO at T144hrs

However the Ens Graph for London shows very little rain in the South East further away from the low out in the Atlantic.

So after a short warm and sunny spell it looks like next week will still be quite warm but less settled with some rain around more notably further west but some dry and bright spells are quite likely especially further south and east.

[jamesay]

Looks to me at the moment like the closing ceremony will stay dry after a warm day on Sunday,with just the chance of a light shower,

[Frank Trough]

It looks quite likely that the dry and warm conditions now extending nationwide could hang on around the Olympic Park until events close on Sunday.

The trough out in the Atlantic moves in slowly into western areas over the weekend but any rain further east will be light and patchy arriving late on Sunday and into Monday.

In the meantime some sunny warm weather is the main theme for the next 3 days apart maybe from the north east coasts and late on Saturday in the far west as the first of the fronts approach.

It does like rain will affect most areas at times into early next week as we see that Atlantic trough edging a little closer as the days go on.

Here the UKMO at T144hrs

However the Ens Graph for London shows very little rain in the South East further away from the low out in the Atlantic.

So after a short warm and sunny spell it looks like next week will still be quite warm but less settled with some rain around more notably further west but some dry and bright spells are quite likely especially further south and east.

indeed. "unsettled" maybe, but pretty warm and decent in the south and south east. This is clearly reflected in the meto updates today which have moved slightly towards a warmer outlook for next week and removing the theme of below average temps for the south and replacing it with likely above average rain for the north and west.

it isn't going to be high pressure dominated but it looks much better than june and most of july for a chunk of the country.

i'm not sure what the exact stats are, but here in Bournemouth we've had very little rain since during the last two weeks. Not great throughout, but totally useable (coincides with me fitting two new water butts on the shed!). It has got better and that looks like continuing.

[Geordiesnow]

The models have peformed well for our part of the world, we know the breakdown for this fine and settled weather will come on Sunday and nothing has changed, It does seem with blocking to our NE and low pressure to our west, winds should tend to come from a mild/warm direction but how far eastwards those lows head is up for debate.

We have seen hints we may see another southerly plume occuring but at this stage, they are only hints but the potential is there. Of course, with such strong heights to our North and East, we are running in the risk of easterly winds and perhaps a stalling low to a our South so be interesting how the models is going to play this out.

[johnholmes]

The NOAA chart gives the general flavour of what to expect over the middle part into the third week of August. All 3 of these anomaly charts are suggesting consistently over the past few days this type of upper air pattern.

I expect similar charts showing tomorrow so that will be the basis of the next 10 day 500mb check. Be interesting to see how near they are to what the actual turns out to be at 500mb for 19 August.

The pattern does not really tie in with the UK Met longer range ideas suggesting the worst of the unsettled weather in the north and west. With a +ve 500mb anomaly over the northern parts of the UK and an upper low south of it one might suspect the situation to be nearer the reverse. But like I've suggested we will know in 11 days time!

Edited August 8, 2012 by johnholmes

[William of Walworth]

Alll to play for for next week then!

[shedhead]

The NOAA chart gives the general flavour of what to expect over the middle part into the third week of August. All 3 of these anomaly charts are suggesting consistently over the past few days this type of upper air pattern.

I expect similar charts showing tomorrow so that will be the basis of the next 10 day 500mb check. Be interesting to see how near they are to what the actual turns out to be at 500mb for 19 August.

The pattern does not really tie in with the UK Met longer range ideas suggesting the worst of the unsettled weather in the north and west. With a +ve 500mb anomaly over the northern parts of the UK and an upper low south of it one might suspect the situation to be nearer the reverse. But like I've suggested we will know in 11 days time!

Well one thing we do know for sure is it won't be dry, warm and sunny, not unless something changes fundamentally that is.

[SP1986]

not warm at night though. been going though the charts this week and they look quite green come next week at nights so it could get quite chilly at night. just thought i point that out. mods sorry if i gone of topic. europe looks set to cool right down at night in fact. i think the high pressege for next week will go and it could not saying it will get quite wet and windy but as ever charts will change and so on.

I wouldn't be so sure about this, well not unless you live on a frost hollow moor situation or something similar. Certainly the temperatures on a nationwide scale won't be as cold at night as the GFS suggests, and certainly not on the locations it suggests. It often occurs to be the predictions are rather generalised and often cover far too big an area, and also the wrong areas when cool nights are predicted. For lowland, and most areas around the UK, the airmass will be too warm and the nights still too short for the temperatures the GFS predicts to occur, on top of that even in clear skies the air will be too humid for such rapid drops (and subsequent rises) too occur as well, and often the atmosphere balances itself out by creating fog to keep a equilibrium.. thus preventing such cold temperatures.

[shedhead]

Really difficult to call the post 'blip' weather for next week based on the overnight runs, with GFS offering plenty of fine dry and fairly warm weather, ECM going for often windy with rain or showers at times and UKMO offering something of a half way house. As throughout most of this Summer I'm going to ignore the very fickle ECM, but GFS also looks far too extreme imo, so it's UKMO's half way house evolution for me.

[Methuselah]

Well the GFS has LP ending-up somewhere near Iceland, which isn't exactly unheard-of...So I can't see anything other than an improvement in our fortunes. Away from the very far NW, perhaps?