Model Output Discussion 31/07/14 onwards.

[phil nw.]

A new thread as we enter the last month of Summer.

 

Current modeling shows a more changeable spell now moving in to the UK as a developing Atlantic trough will be the main influence over the next few days with rain or showers affecting many of us.

Signs as we go into next week of some improvement as pressure starts to rise further south but further runs needed to see how this may develop.

 

There's been some really good discussions in here this Summer so thanks to all our regular posters for that.

 

Anyone not to keen on being to analytical are always welcome to post more general musings on their hopes or moans about the charts in the other thread here-

http://forum.netweather.tv/topic/79882-model-banter-moans-and-ramps-springsummer-2014/

 

Ok on we go then with the 12z runs already out for discussions.

 

[SteveB]

GFS is showing more of an unsettled week next on it's 12z

 

With it chopping & changing as much as it is, I wouldn't put much faith in specifics, but one has the feeling we are not going to see a return to the warm/hot settled conditions for the next week or so.

 

Still, the South East  never really loses the warm air, and temps look to hold up well in the low to mid twenties for most of next week.

 

Elsewhere, mid teens  under the showers/rain, low twenties in any sunshine.

 

 

 

I think I'll take each day as it comes, as I was forecast to have showers for most the day, and I have not seen a single drop.

 

And that forecast was last night

Edited July 31, 2014 by SteveB

[tinybill]

GFS is showing more of an unsettled week next on it's 12z

 

With it chopping & changing as much as it is, I wouldn't put much faith in specifics, but one has the feeling we are not going to see a return to the warm/hot settled conditions for the next week or so.

 

Still, the South East  never really looses the warm air, and temps look to hold up well in the low to mid twenties for most of next week.

 

Elsewhere, mid teens  under the showers/rain, low twenties in any sunshine.

 

 

 

I think I'll take each day as it comes, as I was forecast to have showers for most the day, and I have not seen a single drop.

 

And that forecast was last night

  models  are  not  looking very good  at all for at lest the  first  2  weeks!!!

Edited July 31, 2014 by Polar Maritime
To remove write-off comment .

[Polar Maritime]

Yes yet another unsettled run from this evenings GFS, With the Jet buckling South of the UK or directly over us, And fronts pushing in from the West off the Atlantic bring very wet conditions in places. Nice to see some cooler 850's push South towards the end of the run..

 

Edited July 31, 2014 by Polar Maritime

[Frosty.]

The next three days or so are going to be much more unsettled across the uk with widespread heavy showers and a high risk of thunder but with sunny spells too, as is the nature of showers, some areas may miss them and enjoy lots of warm sunshine but most of us will catch them at some point. Friday night and through saturday, a large area of potentially disruptive rainfall with local flooding is set to push northwards through the uk and eventually become slow moving or grind to a halt over scotland for a time, becoming very windy too in places, especially for scotland but either side of the main rain zone there should be some warm sunshine as well as those sharp showers.

 

Tonight's GEFS 12z mean shows the azores anticyclone ridging up across the south / southeast by early next week with a decent window of fine, very warm and sunny weather for the south and east but the north & west will probably stay unsettled with persistent lower heights to the north west of the uk, the unsettled weather occasionally making inroads southeastwards.

 

Hopefully the Azores high will continue to ridge into the uk through august, I think it will..at least for more southern / eastern parts of england with plenty more very warm sunshine.

Edited July 31, 2014 by Frosty.

[Man With Beard]

ECM has heights further south next week compared to GFS ... courtesy in part to a chunk of northern heights above the Icelandic trough. Now there have been a few instances this summer where the ECM has done this and moved towards GFS later ... so I'm backing the GFS tonight, which is warmer, no drier for most except the SE, which gets very little rain off the GFS 12z.

[ANYWEATHER]

Yes yet another unsettled run from this evenings GFS, With the Jet buckling South of the UK or directly over us, And fronts pushing in from the West off the Atlantic bring very wet conditions in places. Nice to see some cooler 850's push South towards the end of the run..

 

Indeed, looking very unsettled for most from gfs and ecm'. Some brief plumes at times but again the Atlantic looks in charge from both models. I think August will be very different......

[summer blizzard]

A glorious Euro run.

 

While not always cool the 1020mb line fails to get over any of the UK during the entire run.

 

[DAVID SNOW]

Indeed, looking very unsettled for most from gfs and ecm'. Some brief plumes at times but again the Atlantic looks in charge from both models. I think August will be very different......

 

Hello ANYWEATHER can I just ask in what way do you think the WHOLE  of August will be very different?

[knocker]

The anomaly charts tonight are all singing from the same hymn sheet for the end of next week. Upper trough to the NW; warm air to the NE and no great build up of heights to the south.

 

Surface analysis is basically a slack are of low pressure just to the NW which influences most of the UK. The GFS attemtps to perhaps suggest a slight NE movement of the Azores ridge but the position of the jet suggests this is about all it is. Temps about average.

 

[draztik]

The ecm ens. mean reluctant to drop the trough to our West, with its presence throughout... "the hottest August for 300 years" may be a slow burner based on the above post from knocker and the output tonight.

Days 5-10,8-13 height anom.

Temp anomaly days 5-10

Edited July 31, 2014 by draztik

[ANYWEATHER]

Hello ANYWEATHER can I just ask in what way do you think the WHOLE  of August will be very different?

There is no indication from the models that there will be fine weather all the way through august first half looks unsettled, second half !,?..

[Tamara]

We should therefore expect a warmer version of the last UK trough dominated/
more unsettled spell, but should watch in the models in the coming days for the
pattern to keep evolving and changing towards a flatter atlantic profile as
energy transport across the NH manifested through effects of changes once more
in the Pacific jetstream filter downstream.

The upstream atlantic high pressure should eventually de-amplify in response,
with a shift in troughing orientation towards the NW of the UK introducing a more tropical maritime influence following the slack NW'erly, and rather weak,
polar maritime phase of the coming week.

This should encourage something of a NW/SE split in the weather after a more
generally changeable spell around next weekend.

What about after that? More cyclical evolution to come as a downstream ridging
response occurs following the increased energy upstream and extends from the
south west to settle things down again further south. A good chance that such an eastward moving ridge may in turn extend into Europe/Scandinavia as per recently and coincide with a split energy in the atlantic and hence another cut off low to engage the next plume perhaps towards mid month.
 

Edited by Tamara תָּמָר, 26 July 2014 - 16:34 .

 

Truncated edits from the previous post that remain pertinent and consistent to this update

 

The flatter atlantic pattern is on cue to give traditional summer conditions to the UK with the aforementioned suggested NW/SE split advertised fully within the models as we head past a briefly more generally unsettled couple of days over the weekend. This I think gives some perspective to some other posting which I think is based on preference rather than reality

 

At the present time, only this mornings London ECM ensemble suite is available to peruse for the medium/longer term temperature trends, but the parameter boundary extents of this data solidly support average to above average temperatures throughout the coming 10 days and beyond and there is not scope for sufficient deviation in this data to alter the mean trend to anything less than sub 20 to 25C for some time to come.

 

http://www.weathercast.co.uk/meteo/eps/ensemble-tt6-london.gif

 

We do have tonights 12z EPS ensemble member maps to scrutinise which are available out to day 5, and we see there is good support for the weekend UK trough to be sufficiently retrogressed into next week to fully utilise sub tropical/continental downstream ridging from the Azores into Scandinavia and there is more than enough direction of travel momentum away from any resurgent UK wide cool, trough solution (with trending support instead for the cyclical evolution as suggested in previous update) to make a nonsense immediately of any impending trend to an August 'write-off' as we head through the opening week of the month. Even in the wetter more unsettled NW areas there is no suggestion of anything less than average for the mature summer period we have arrived at.

 

 

 

A brief and less detailed update than usual here then - but hopefully enough to be going on with in the meantime to give a little unbiased perspective as to what is likely in the reality instead of individually hopecasted predictions

Edited July 31, 2014 by Tamara תָּמָר

[johnholmes]

It is very easy to take one or perhaps 2 model runs, any model and make 2+2 seem to equal anything but 4. Not for any malicious reason but purely as the poster I suspect wants one weather type or another.

If we look realistically at what the upper air pattern and hence the surface weather may be then it does look like an upper trough will be the main player for the 6-10 day period, indeed starting tomorrow with a quite marked surface feature moving into the UK, care of the marked upper trough. So maybe 1-10 days ahead and no real sign of any major improvement other than temporary ones as weather systems move away. Not especially on the cool side but no real sign of any return in this time scale of the widespread, note the word, July values for many areas. Sure the odd day here and there will be very warm even muggy depending on the actual surface flow that day. Any sunshine in more southern and eastern areas giving temperatures into very warm (bY Met O definition for early August) but no widespread heat or settled spells.

As to beyond 10-12 days then the latest NOAA 8-14 is perhaps as close as anything we can find on the web, this still suggests unsettled/changeable rather than settled. That is not to decide that August is a write off. Think back to late June and what some folk suggested for July and how that month has turned out for many areas-not quite the same was it?

 

NOAA latest anomaly charts

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

[Polar Maritime]

Tonight's GFS is showing a plume pushing North over the UK out in the run, A stark difference in runs shows great uncertainty.

 

Edited July 31, 2014 by Polar Maritime

[William of Walworth]

Surely not just a plume that PM?

 

(To me the term 'plume' suggests short lived, UK-clipping heat/instability. Or am I wrong?)

 

If anything anywhere near the above came close to verifying for that time around mid August. we'd surely be looking at somewhat more resilient and widespread HP domination?

 

Or am I misunderstanding that chart .... ?

Edited July 31, 2014 by William of Walworth

[William of Walworth]

Excellent posts from Tamara and John btw. I find it hard sometimes to follow that level of detailed analysis, but guidance from experts is always good for less informed amateurs like me ...

 

And more selfishly for me, I see only quite limited scope for extreme August washouts from what both of them are suggesting,

[SteveB]

The GFS is still looking unsettled, but not a complete washout, with the unsettled weather taking the form of showers

 

 

 

 

The continent looks hot through out, what would it take to tap into that heat again?

[Polar Maritime]

Surely not just a plume that PM?

 

(To me the term 'plume' suggests short lived, UK-clipping heat/instability. Or am I wrong?)

 

If anything anywhere near the above came close to verifying for that time around mid August. we'd surely be looking at somewhat more resilient and widespread HP domination?

 

Or am I misunderstanding that chart .... ?

 

At the moment that is all I would call it, Weak signs are still there this morning in the last few 2/3 frames way out in FI so not worth going into any detail. As i said last night, Lot's of wild swings at this range.

 

 

But there's a lot of water to run under the bridge before then, With the GFS continuing to show unsettled & wet pattern off the Atlantic.

 

Edited August 1, 2014 by Polar Maritime

[Man With Beard]

Slight role reversals from GFS and ECM this morning. Both have NW/SE split Mon-Weds next week, but after that GFS has copious amounts of rain, whilst ECM heats us up in time for a week end storm. Both seem at the extreme ends of charts in general.

Interesting both GFS and GEM still bring ex-hurricane into play at D9 - with huge impact on our synoptics

[Summer Sun]

Way out in FI but if this low did come off thunderstorms could be fairly widespread in the east given the 850's

 

[knocker]

The GFS and ECM anomaly has a familiar ring for next weekend. The trough still centred Iceland with perhaps the GFS pushing it slightly further east. The warm air still to the NE and little build up of heights to the south and this lack of amplification of the Azores high is a feature well into the following week giving a west/east Atlantic flow.

 

So the surface synopsis is much the same with a slack area of low pressure over the UK with the Azores ridge doing it's little nudging job but the jet is still positioned to limit any development. Temps on the whole around average but briefly quite warm in the SE towards the end of the week although the ECM scuppers that with a pretty cold day on Sunday.

 

N.B. After the weekend observations are just that.

 

 

Edited August 1, 2014 by knocker

[Tim Bland]

Warm / Hot plume only reaches the South East though. In Manchester Temps are around 20C Whilst the SE could be up to 28C.

 

ECM looks better for Thundery weather!

 

http://www.wetterzentrale.de/pics/Recm1682.gif

http://www.wetterzentrale.de/pics/Recm1922.gif

http://www.wetterzentrale.de/pics/Recm2162.gif

Edited August 1, 2014 by Tim Bland

[Scorcher]

Looking at those GFS charts I don't think it's a true plume anyway- most of the really hot air misses the UK and most of the country would have a SW wind as opposed to a direct southerly which I usually associate with plume scenarios.

[Gael_Force]

Looking at those GFS charts I don't think it's a true plume anyway- most of the really hot air misses the UK and most of the country would have a SW wind as opposed to a direct southerly which I usually associate with plume scenarios.

 

There has been a problem even getting plume conditions to the north of Spain this year - very pronounced rex block in the 500mb anomaly charts for summer so far.