Model Output Discussion - 1st July Onwards 18z--->

[knocker]

The GEFS anomalies this morning are not good although things do improve post day ten only for the upper trough to park itself to the NE.

 

Earlier it continues with the idea it has been playing with which is the broad area of LP northern Europe/Iceland with a trough orientated SW into the Atlantic. Tends to herald depressions winging into the UK on a NW/W flow bringing unsettled weather. It does retract the trough in later time frames leading to more benign westerly flow.

http://www.tropicaltidbits.com/

 

[Summer Sun]

Watched the excellent weather presentation from Alex Deacon this morning on Breakfast News. His chart showed a waving weather front to effect mostly Southern Britain for the next 2 days at least. Then he referred to a development taking place well southwest in the North Atlantic which could turn into a deep depression. The track and positioned not yet determined. If it goes on a more southerly track, hot air could well be imported on Thursday, further North then much cooler flow for most. Early days yet, but could be one to watch. An interesting week ahead I think.

C

 

Speaking of hot air on Thursday thats leads us onto GFS

 

Mid to high 20's quite widely in the south maybe 30c somewhere meanwhile across in France and were widely in the mid to high 30's could be looking at 100f in Paris

 

Edited July 13, 2015 by Summer Sun

[knocker]

Not a huge difference between the GEFS and ECM this morning co still looking at the dreaded N/S split. In the ext period the ECM much more bullish with trough extending down over the UK. Not looking brilliant and certainly no sign of any extended warm weather for the whole of the UK

http://www.tropicaltidbits.com/

 

[Man With Beard]

I'm going to revisit my analysis of the models which I started last week. The day in question is tomorrow (Tuesday), and I compared how the GFS and ECM forecasted this date at different intervals. Rather than redirect back several pages, I will repost the images again.

 

First, this is how tomorrow currently looks (T24)

 

This is how the GFS and ECM were at T192:

 

 

I'll call round one to GFS. The ECM has got heights south of the UK reasonably correct already (focus on the colours), but is miles off for heights north of the UK. The GFS has done fairly well with heights to the north, but has over-amplified the mid-latitudes, and therefore the situation over the UK is drastically different to how it will actually be. But the ECM has overdone the low crossing between Iceland and Scotland and so GFS is slightly ahead, all things considered.

 

T168:

Still not particularly close from either, but ECM is now ahead. It is getting a better grip on the northern heights (still not quite there), and the pattern to the south remains flatter than GFS, although too far south. The GFS still has the Azores High ridging in too much, and takes a small step backwards on Greenland heights. Both of them overdo the low this time, and GFS also overdoes the low exiting the US.

 

T144

Difficult to pick a winner here because they both made crucial mistakes even at this timeframe. The GFS still over-amplifies the pattern over the UK. However, the ECM still overdoes the incoming low, and again has it too far south. ECM still slightly better to the south - both made different mistakes to the north.

 

T120

 

At last, both models are seeing the pattern much more clearly. They've both slightly overdone a low pressure over the UK, the low exiting the US and and high pressure over the Atlantic. The ECM edges it though as it is now better for northern heights and has picked up on a developing trough in the mid-Atlantic.

 

Now I got a fair bit of criticism last week for claiming T120 charts could be relied upon, but as it turned out, the models weren't too far off at this stage. I note too that the models were fairly accurate once they were in agreement - perhaps a lesson there.

 

However, what I was wrong to do was to claim the ECM was a long way ahead of the GFS. If one looks purely from a line running through, say, London, and only looked south, the ECM clearly was on the ball throughout - but other things were happening to our north that the GFS picked up on sooner, on the whole.

 

The big errors were GFS overdoing Azores ridging, and the ECM overdeveloping Atlantic lows. In the ECM's case, perhaps we should be treating charts like these with more caution:

 

 

and recently, the GFS has tried many times to build Atlantic heights toppling towards the UK, but none such charts seem to get close to the reliable timeframe:

 

 

Just something to remember down the line, perhaps.

[summer blizzard]

6z is as you were. Largely unsettled but warm in the south at times.

[Frosty.]

6z is as you were. Largely unsettled but warm in the south at times.

It's not largely unsettled at all, the south and east have a lot of fine and warm weather on the 6z.

[Milhouse]

The models keep throwing up very nice runs from time to time, but still too infrequently to definately call another summery spell round the corner. What is for sure is after the coming weekend we are likely to enter a spell of warm moist southwesterlies. How much north high pressure builds is still far from certain.

[Man With Beard]

GFS 12Z is a cracker after T144!! Azores high ridging through almost all parts of the UK and sticking around several days.

I really hope my little theory of GFS overdoing Azores High incursions is wrong...

[Captain Shortwave]

Day 6 charts

GFS

 

UKMO

 

GEM

 

All three show some form of Atlantic trough with a ridge being thrown up ahead of this across the south of the UK. The GFS turns hot with high pressure centred over northern Europe, the GEM looks more transient.

All looks to be going to plan, not suggesting a prolonged spell of hot and sunny weather here, just pointing to the next warmer period in this mobile pattern. Of course the one prior to this is this Thursday (still 28/29C predicted in the south).

[Mark Parsons]

not true..... i was on tablet last nigh so couldnt produce supportive charts... but post 336 by frosty highlights the gfs 12z high pressure dominance after the weekend (dropped now though, for now).

heres the ecm 12z

high1.gif high2.gif

so at the time my post was made, it was correct, both the ecm and gfs DID show high pressure dominance after next weekend. the charts are there to be viewed.

but the 00z gfs (didnt see the 18z) has dropped any lasting high pressure build until after day 10, the ecm 00z is rolling out as i type and i expect will drop its version of high pressure building. the ever reliable noaa anomaly charts do not support a lasting high pressure build. but. niether do they support such a low pressure dominated gfs 00z.

as i interpret it, its looking rather average or just below par.... but gibby will present a far better appraisal soon.

In hindsight quite a good shout with high pressure now due over the weekend and in to next week! 

[summer blizzard]

GFS very interesting days 6-9..

 

[Frosty.]

The Gfs 6z showed a lot of fine and warm weather away from more northern / northwestern parts of the UK but the 12z becomes very warm / hot next week with even the n/nw noticeably less unsettled and warmer at times. It would be great if we get to see charts as good as these within the reliable timeframe. The met office extended outlook is generally very good, especially for England and wales so I expect we will be seeing more runs like this in the days ahead.

[stodge]

Evening all

 

My first chance to catch up with the models after several days and the NAO continues to interest:

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

 

Very negative at present but while most members take the index back to neutrality, a couple keep it very negative.

 

A negative NAO given the current synoptics is exactly what fans of heat want to see as it suggests pressure remaining low to the south-west and west indicating an Atlantic trough digging south and forcing hot continental air north from France and Iberia. The problem with the last hot spell was there was no strong HP to the east of the British Isles to keep the S'ly airflow in place so it got displaced fairly rapidly by the Atlantic.

 

That may well happen again - on the other hand, if you want to see the Azores HP ridging over the British isles, you really want to see that NAO back toward neutral or even into positive territory. A weakly negative NAO is really nowhere as the trough isn't strong enough to force advection from Iberia but it is strong enough to keep the Azores HP suppressed.

 

My money (and very nice money it is too) would be on the possibility of more plumes but their duration and extent would be far from clear as the month progresses.

[mushymanrob]

The models keep throwing up very nice runs from time to time, but still too infrequently to definately call another summery spell round the corner. What is for sure is after the coming weekend we are likely to enter a spell of warm moist southwesterlies. How much north high pressure builds is still far from certain.

 

i think this is a good thing though. in washout summers we never got close to a building ridge, at least this summer high pressure has never been far away, and whilst so far its failed to build and produce a lengthy settled spell (with the accompanying sun and heat).

 

but surely its only a question of when we get a decent lengthy anti cyclonic spell, not 'if'...

[Milhouse]

 

i think this is a good thing though. in washout summers we never got close to a building ridge, at least this summer high pressure has never been far away, and whilst so far its failed to build and produce a lengthy settled spell (with the accompanying sun and heat).

 

but surely its only a question of when we get a decent lengthy anti cyclonic spell, not 'if'...

 

Yes Mushy, we do seem to have come out of that spell of cool northwesterlies during May and June when low pressure always wanted to dive into central europe. Now, despite worrying heights over greenland, we do seem to be in a better position for pressure to build favourably bringing winds from a warmer direction.

[Summer Sun]

Nice looking GFS tonight just need some consistency before I'll build my hopes up over to ECM now

[Frosty.]

The GEFS 12z mean shows there is good support for the Azores high to have an increasing influence on the uk weather next week with a warmer and settled spell, at least for England and Wales.

Edited July 13, 2015 by Frosty.

[knocker]

This evenings GEFS anomaly continuing to look not too clever with trough Russia and the eastern Atlantic and no signs of HP activity. with the jet (what there is of it) running around the established upper low  So remaining unsettled and generally cooler than average except for periods in the south of the UK. The ext period doesn't instill optimism either with the trough over the UK.

http://www.tropicaltidbits.com/

 

[ANYWEATHER]

North/South divide on the ecm tonight at 240 hours ahead, wouldn't be surprised if it came to fruition:

http://www.meteociel.fr/modeles/ecmwf.php

Again meaning northern and western parts of the uk get the more unsettled cooler conditions wheras southern and eastern regions get it brighter and warmer, but still prone to rainy events a tad.

To be honest, gfs and ecm are really struggling with the outlook from the weekend onwards, tomorrows output will give us perhaps a little clue on where we are going. High level of Shannon entropy!!!    

[Summer Sun]

ECM illustrates why my confidence remains low in what GFS shows on its 12z although very warm / hot at times especially in the SE high pressure just can't establish its self for more than a day or so

 

[knocker]

Have checked the noaa anomoly charts for 6-10 days and 8-14 days ahead and it looks like a westerly pattern continued from the weekend. Except there is below average to near average confidence in this.

 

Yes and if you compare the NOAA 6-10 and the GEFS T216 there is good agreement. The mods are active tonight so not sure how long this will remain.

[Methuselah]

I see no great probs with the 12Z: When I was by Inverness, 19-21C was fine; it's only since being back darn sarf that things have turned nasty...If it ain't 30C, and wall-to-wall sunshine, every day, it's hari kari time...Aaaar Soh!

[Mark Parsons]

What I never understand on this thread is that the meto give out a positive outlook ( and often they are right ) but on here you go off on one which often ends up being completely wrong? Ok there are other scenarios but come on the pro's are calling high pressure and nice summer weather post the weekend which will probably prevail, sorry if off topic!

[Milhouse]

The ECM mean is going for very warm southwesterlies for a time giving a NW/SE split. Rather than a full on pressure rise.

 

Edited July 13, 2015 by Milhouse

[knocker]

The ext ECM is still looking at an area of LP N. eastern Atlantic/N. Europe with a trough over the UK not dissimilar to the the GEFS.