Model Output Discussion 31/05/14 onwards.

[Milhouse]

The GEM tends to throw in extreme outcomes from time to time, and we have seen time and time again during the last 6 months how northerlies do not materialise. The ECM mean does show pressure falling around the end of the week but rising again from the southwest towards the end. Id say this was looking quite reasonable for the start of July.

 

 

 

[draztik]

Maybe worth keeping an eye on the Azores high as we move to July the ECM ens shows it starting to move towards us albeit slowly it would still keep the weather mostly settled for most parts

 

 

Indeed. However, after day 10 the ecm ensembles trend more unsettled

 

by day 12 / 0z ecm ens

 

/ecm control - by day 12 has a rather deep low affecting UK! looking quite nasty,(normal caveats apply)

 

As ever, time will tell. Wimbledon looks like getting a good start. By midweek, things beginning to look dodgy.

Edited June 22, 2014 by draztik

[knocker]

The ECM ens going along with the upper trough and cyclonic scenario.

Edited June 22, 2014 by knocker

[mushymanrob]

I think the pattern is clear enough from about mid week, that is an upper air pattern more trough than ridge governed. This, and I take no credit for it, it is the guidance from the anomaly charts, is now showing quite definitely as Met refine their charts from around Wednesday to show surface troughing more likely than ridging.

Decent weather to start the week but declining from the NW as the week progresses is about the the most likely output it seems to me. This pattern to be kept into the start of a new month.

 

 

just picking up having read what mushy posted.

Of course you don't take any chart as gospel. But what has to be taken as the most likely outcome is an amalgamation of model/chart/human outputs all pointing to about the same conclusion.

Realism and objectivity rather than hoping for something that we might prefer?

 

fair point john, i guess im trying to deny what i fear, although i know the upper pattern is likely to be trough governed , i guess im hoping something more anticyclonic wil emerge. so guilty of ignoring realism in favour of hopeseeking.i think what isnt clear though is the nature of the upper trough dominance, it does look pretty weak, and the latest gfs anomaly appears to suggest an azores ridge towards us which shouldnt make things too bad IF that becomes reality. as i see it, its looking pretty normal british summer weather, no heatwave but no monsoon either.

[knocker]

Indeed. However, after day 10 the ecm ensembles trend more unsettled

 

by day 12 / 0z ecm ens

 

 

 

/ecm control - by day 12 has a rather deep low affecting UK! looking quite nasty,(normal caveats apply)

 

As ever, time will tell. Wimbledon looks like getting a good start. By midweek, things beginning to look dodgy.

 

Funny enough.

[damianslaw]

I've said in a number of recent posts, how late June is a pivotal period - a transitional period when the northern hemisphere traditionally settles into its summer state, its always a tentative time in this respect watching where the jet positions itself and how the azores high interacts with it - the two dominating features of UK weather above all else.

 

There are ominous signs that the jet looks like it is firing up on a poorly positioned axis for settled warm conditions to make there presence felt - a more west/nw - east/se trajectory thanks to strong heights to the north, forcing the azores high to slumber well to our SW. This time last year we saw the jet take a northward flight allowing the azores high to build NE setting the country up for a lovely July and not too bad August.

 

However, the jury is still out, but if we enter July with such a positioned jet, it may well be its set position for the rest of the summer, keeping the heat bottled to the south.

[Evening thunder]

I thought the 'return of the westerlies' was a normal thing in late June, if so why is that necessarily ominous? I won't really take FI model charts suggesting a more west/east jet axis across the UK, or an unsettled few days, or the odd deep low picked from anomalous ensemble members to suggest we won't get any heat this summer, or a decent July or August.

[knocker]

I've said in a number of recent posts, how late June is a pivotal period - a transitional period when the northern hemisphere traditionally settles into its summer state, its always a tentative time in this respect watching where the jet positions itself and how the azores high interacts with it - the two dominating features of UK weather above all else.

 

There are ominous signs that the jet looks like it is firing up on a poorly positioned axis for settled warm conditions to make there presence felt - a more west/nw - east/se trajectory thanks to strong heights to the north, forcing the azores high to slumber well to our SW. This time last year we saw the jet take a northward flight allowing the azores high to build NE setting the country up for a lovely July and not too bad August.

 

However, the jury is still out, but if we enter July with such a positioned jet, it may well be its set position for the rest of the summer, keeping the heat bottled to the south.

 

I'm afraid this confuses me a little. Although it's quite complicated will not the Polar jet be associated with the steep temperature gradient between the polar and tropical air and thus is dependent on the properties of these two air masses and to some extent is dictated by this? This being the case I'm not sure what you mean by interaction except that it's  position and strength will depend on the subtropical surface high. Basically its a case of what is dictating the interaction? Plus it's quite common for it to be  irregular in it's longitudinal location in summer.

Edited June 22, 2014 by knocker

[summer blizzard]

GEM and Euro aim the jet directly at the UK this morning albeit lows don't look too strong.

[MP-R]

I may be missing something here but I've noticed the GFS backing away from a strong jet recently. The last few days showed a deep autumnal trough arriving on June 30th and exiting the UK around the 2nd July. Now however there are trends of much weaker troughs ending up, cut off from the main area of low pressure to the northwest. The second factor to note is high pressure to the NE, SE and SW at the turn of the month. Personally, I can't see how any trough will last more than five minutes when the main supply of cold air is cut off - it's only a matter of time before there's a link up of high pressure somewhere. As things currently stand, I think it's more likely to be a showery scenario into July rather than a typically autumnal one like 2007 and 2008. Nuisance cloud, cooler temperatures and intermittent periods of rain rather than a full-on washout with an equal possibility that the Azores high will arrive later.

[knocker]

The question is does the 06z anomaly and surface support this?

 

[Gael_Force]

I thought the 'return of the westerlies' was a normal thing in late June, if so why is that necessarily ominous? I won't really take FI model charts suggesting a more west/east jet axis across the UK, or an unsettled few days, or the odd deep low picked from anomalous ensemble members to suggest we won't get any heat this summer, or a decent July or August.

 

UK .sci.weather have a page devoted to those 'singularities' which we see mentioned at various times of year.

 

http://weatherfaqs.org.uk/node/179

 

In any of the articles I've read about return of the westerlies, the emphasis has been on the jet stream taking a more northerly route into northern Europe during June - not at all the same as recent digging south of troughs over the BI and Iberia during any month in summer season. This seems to be some new sort of summer phenomenon for which the causes can be open to debate.

[Summer Sun]

Not a bad update from UKMO this afternoon with it showing pressure rising at t144

 

 

Will be interesting to see how this pans out over the next few runs to see if it has any support

Edited June 22, 2014 by Summer Sun

[Captain Shortwave]

Well so much for a clearly unsettled end to the week. The UKMO has suddenly realised that there is high pressure to the north and sends the low into France instead of the UK

 

GFS is bringing barely any significant rainfall to the UK, just a few showers here and there.

Still a lot of uncertainty even in the more reliable timeframes.

 

GEM is different to both at day 5

low pressure squeezing through slowly instead of the quick UKMO solution and the GFS solution where low pressure fails to reach the UK.

Edited June 22, 2014 by Captain shortwave

[IDO]

By D8 GFS and GEM bring rainfests to the UK:  GEM:

 

GFS in FI keeps LP over the UK right out till the end of the run for washout weather:

 

Some of the ECM members also showing copious amounts of rain in FI: 

 

The trend is for a cluster of members showing a very wet outlook in week 2, from both GEFS and ECM. Too early to take serious, but not a good development. The GFS op obviously sits in that very wet grouping so low confidence at the moment but remains a possibility.

 

GEM has a westerly flow by the end of the week that's with us till the end of D10:

 

 

The outlook for lower heights becoming more likely as the models update. How long it will last is probably now the question? At D6 the UKMO handles the brief respite from the NW flow by building heights (temporary or not?), GEM just pushes the next wave of Atlantic energy through, whilst GFS stalls a low just to the west of Ireland for a few days and by D9 the next pulse of Atlantic sends the low through the UK.

 

So at the moment heights lower from the North during Thursday and remain lower on Friday, so for the south, average temps and showers look likely; the NW the wettest and coolest. After that it could take a turn for the worse or it may not!

Edited June 22, 2014 by i'm dreaming of...

[Milhouse]

Not a bad update from UKMO this afternoon with it showing pressure rising at t144

 

 

Will be interesting to see how this pans out over the next few runs to see if it has any support

 

And notice the lack of low pressure out in the Atlantic. Not really a strong Azores high but it would still bring summery conditions once it pushes in.

 

A reasonable GFS too in the low res section so another 7 days of warm temps, nothing cool, but a greater risk of showers breaking out next weekend.

[Milhouse]

Well the ensemble mean for next weekend looks a bit like this. Seems to be supporting the op in placing lower pressure to the SW of the UK and higher pressure over and to the north of the UK.

 

[Summer Sun]

I hope they are onto something Gavin, by the way how do the GFS ensembles look tonight?

 

GFS ensembles are here: http://www.wetterzentrale.de/topkarten/fsenseur.html - not looked at them yet

[SteveB]

GFS shows another warm week for the bulk of the UK, with showers only affecting Ireland & Scotland early in the week, but becoming more widespread as the week progresses.

 

 

 

 

 

[Captain Shortwave]

ECM

Similar to the UKMO, low heights pushing through the channel, north dry, some rain for the south. There could be some desperate scribbling going on for the countryfile forecast as this doesn't reflect the lunchtime forecast at all

Interesting how the UKMO and ECM has suddenly developed a 1025mb high near Scandinavia which didn't exist this morning. Nice little spot from the rather bashed GFS there. If that high does verify of course.

 

Theme from the ECM tonight is cool, dry and bright.

Edited June 22, 2014 by Captain shortwave

[knocker]

The ECM ops anomaly at the end of the month still knocking out the swathe of cold air stretching west to east across the Atlantic and it's surface analysis is consistent with this.

Edited June 22, 2014 by knocker

[Milhouse]

ECM 12z looking rather nice from 168h onwards. The only problem being the origin of the high pressure that eventually takes up residence over the UK. Its a rather cool source of air so we would need an injection of continental warmth to get temperatures rising. But what it does show is after an unsettled blip at the end of the week the dry and pleasantly warm conditions would be returning.

[stodge]

ECM 12z looking rather nice from 168h onwards. The only problem being the origin of the high pressure that eventually takes up residence over the UK. Its a rather cool source of air so we would need an injection of continental warmth to get temperatures rising. But what it does show is after an unsettled blip at the end of the week the dry and pleasantly warm conditions would be returning.

 

Well of course but it's one evolution and at present out on its own though of course we don't have the luxury of a UKMO T+240 chart to see if a similar evolution was thrown out from Exeter.

 

GFS and GEM head down the unsettled route with pressure falling to the south west and later across the south of England and FIM (not surprisingly) heading the same way;

 

http://modeles.meteociel.fr/modeles/fim/runs/2014062212/fim-0-204.png?12

 

JMA goes its own way and offers a different evolution:

 

http://www.meteociel.fr/modeles/jma/runs/2014062212/J156-21.GIF?22-12

 

To be fair, that breakdown is brief with a new HP to the south of Iceland  offering a renewed settling down but not from an overtly hot direction mercifully.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014062212/ECM1-240.GIF

 

Chart of the evening for fans of HP but it is a long way off and the models have been nothing if inconsistent. IF it verifies, huge kudos to ECM for spotting this trend. That said, looking at the 850s not much different from now and indeed a deal cooler over Europe so perhaps not the heat-fest some might be expecting from the synoptics.

[Summer Sun]

This unsettled spell could just be a blip if ECM is to be believed

 

[IDO]

ECM and GFS ops not much difference in long wave pattern at D8:

 

ECM:   GFS: 

 

Both have weak heights north of the UK and an upper low to the west; the GFS is off the west coast of Ireland, ECM further west. JMA is even further west:

 

 

​They then go there separate ways. GFS gunning up the Atlantic and ECM pumping up the ridge. Each are notoriously guilty of over playing their parts so not sure who is right or a middle ground? Looking at the GEFS for T192 there is only one member close to the ECM op and it gets there a different way and is only a transient ridge. Also the NOAA 6-10 day anomaly not really going with ECM op anomaly:

 

 D9 ECM op:  D10 op: 

 

ECM D10 mean: 

 

So maybe I slightly side with GFS, at least for tonight, though confidence level remains very low after D6.