Model Output Discussion 12z 30/06/13

[Evening thunder]

GFS 12z brings slightly cooler uppers back (though not like the 00z). The UKMO looks like it might do it a little more than GFS. However still maintaining the very warm mostly sunny theme with great summer weather

 

Also with the GFS uppers, while with elsewhere especially land areas like Europe the uppers warm a tad in the aftternoon like you would expect, the GFS keeps making a cooler pool pop up over the south of the UK instead at 4pm, which then fades away during the night..

Here's an example from tomorrow but it happens on other days through next week too:

11am: 11C uppers over the south http://91.121.16.5/modeles_gfs/runs/2013070412/21-7.GIF?04-12

1pm: perhaps the first sign of the 11C line receding west of London: http://91.121.16.5/modeles_gfs/runs/2013070412/24-7.GIF?04-12

4pm: uppers else where have warmed slightly with a day, except suddenly there's a pool in southern England which is 2C colder: http://91.121.16.5/modeles_gfs/runs/2013070412/27-7.GIF?04-12

This gradually drifts and fills during the evening/night. The location can very a bit but usually southern England has some kind of afternoon reduction, I think the 06Z showed it better later next week.

 

This is probably a bit of a technical question that no one may know, but is this some flaw in the GFS charts/calculations, or is there something odd about the UK?

Would this effect max surface temps? or should I just dismiss it.

[draztik]

Hope that the 12z GFS FI does not come to pass, as it has low pressure stuck over us for days at the end of its run!!

[Cheshire Freeze]

Hope that the 12z GFS FI does not come to pass, as it has low pressure stuck over us for days at the end of its run!!

 

Entirely possible and has been a recurring trend towards the latter end of recent runs. Let's hope we get a good thundery send off to the fine weather! That would do me.

[East_England_Stormchaser91]

Hope that the 12z GFS FI does not come to pass, as it has low pressure stuck over us for days at the end of its run!!

I think that will definitely alter. If that did happen though, some awesome convection would likely occur due to the very hot ground after being stuck for days under hot sunshine. 

Anything after 5 days out is still very open for debate IMO.

[Captain Shortwave]

Hope that the 12z GFS FI does not come to pass, as it has low pressure stuck over us for days at the end of its run!!

It's not that bad, just a shallow cut off trough, would bring average temperatures and showers, doesn't look like any prolonged rainfall except for slow moving showers

[Tamara]

These individual ECM ensemble maps have been interesting to watch and compare daily out to 7 days, since this fine very warm summer spell came reliably under the model radar, and plot progress of them against the occasional tendency of the operational model (and GFS) to retrogress the High into the atlantic and bring cooler air southwards plus slightly less settled conditions.

 

Time has, so far, confirmed well that such output has been unduly progressive because the maps are almost identical today to yesterday, f.e, and the day before... and we are another day rolled forward.

 

So today, it can be seen that once more there is emphatic agreement to virtually the end of next week for this summer spell to last, at the very least till then with very very few solutions having the High pulled back to any degree. Most all of them keep the High more or less in a sandwich from the eastern atlantic on one side, centrally across the UK, into NW Europe on the other side - and it remains a flat pebble shape with the jet stream showing no amplification to the north and west which might signal such a retrogression.

 

 

I think that this signal is taking us ever closer towards mid month when we might expect to see perhaps some frontal activity after next following weekend come closer to some northern parts. But this is some way off for sure and shows that there is a good deal of fine summer weather to come and to enjoy

 

So, things continue to tie in nicely with snowkings regular updates on progress and change. His suggested timetable for pattern changes and evolutions since the Spring and into early summer has been impressively accurate imo and deserves credit. Along of course with others, like just for one example Frosty, who have daily plotted the development of this fine spell very well

 

The updated UKMO 12z late this afternoon reflects this mornings ECM maps quite nicely with that spread of High pressure, as just described at day 6 (taking it into virtually the same time period as the ECM 0z)  Its a case of 'spot the difference'. There is none at all.

 

Edited July 4, 2013 by Tamara Road

[Geordiesnow]

Looks to me both the GFS and UKMO wants to move the high slightly NW'wards which may result in more  low cloud being toppled into Eastern areas mid week next week. A change of orientation would change this but it would be ashame if this does happen though. 

 

And even the BBC is suggesting a zone of thicker cloud toppling in on Sunday, which I'm glad they are mentioning that as that would stop the argument only the "far north" will be affected or everyone will have blue skies and sunshine. 

 

All in all, a settled outlook but there is hints mid week next week could turn cloudier with low cloud coming into play if the high starts the head slightly NW'wards. 

[mushymanrob]

below average SSTs and a rather keen enhanced sw'ly over the top of the high  might have a bit more cloud up there also i feel 

 

indeed, i think we have overlooked the possibility of spoiling cloud, (i see geordiesnow has just mentioned it too). i think this is a possibility with the high centred over the northern irish sea/ northern ireland.

 

could it all go wrong?...

[Buzzit]

indeed, i think we have overlooked the possibility of spoiling cloud, (i see geordiesnow has just mentioned it too). i think this is a possibility with the high centred over the northern irish sea/ northern ireland.

 

could it all go wrong?...

No it couldn't Never seen so many summer junkies out at once Keep the faith

[Mark Bayley]

A very warm and pleasant spell of weather over the next few days, perhaps lasting well into next week. Although if the high drifts further NW, as in the GFS, then some areas could see issues alluded to by geordiesnow. Longer term and there seems no conclusive signal as to what the 2nd part of this month may hold. Theres great variability in the MJO forecasts, with amplitude remaining low.

There are hints that the NAO may return negative into the 2nd half of the month, although again there is a great deal of variability in the ensemble suite

I think its fairly certain that it will remain warm, and sunny, for most, well into the next week. 

Edited July 4, 2013 by Mark Bayley

[gottolovethisweather]

Also with the GFS uppers, while with elsewhere especially land areas like Europe the uppers warm a tad in the aftternoon like you would expect, the GFS keeps making a cooler pool pop up over the south of the UK instead at 4pm, which then fades away during the night..

Here's an example from tomorrow but it happens on other days through next week too:

11am: 11C uppers over the south http://91.121.16.5/modeles_gfs/runs/2013070412/21-7.GIF?04-12

1pm: perhaps the first sign of the 11C line receding west of London: http://91.121.16.5/modeles_gfs/runs/2013070412/24-7.GIF?04-12

4pm: uppers else where have warmed slightly with a day, except suddenly there's a pool in southern England which is 2C colder: http://91.121.16.5/modeles_gfs/runs/2013070412/27-7.GIF?04-12

This gradually drifts and fills during the evening/night. The location can very a bit but usually southern England has some kind of afternoon reduction, I think the 06Z showed it better later next week.

 

This is probably a bit of a technical question that no one may know, but is this some flaw in the GFS charts/calculations, or is there something odd about the UK?

Would this effect max surface temps? or should I just dismiss it.

 

Isolated storms perhaps or wind convergence zones?

 

Personally, I wouldn't get wrapped up in the specifics as they will change on a day to day basis with members from certain areas perhaps getting disappointed by a strengthening wind or additional cloud cover on certain days. At the end of the day, the rarity of UK wide High Pressure is there to be largely enjoyed by almost everyone. I will be one who will be watching the daily maximum Temperatures unfold.

Edited July 4, 2013 by gottolovethisweather

[snowking]

A very warm and pleasant spell of weather over the next few days, perhaps lasting well into next week. Although if the high drifts further NW, as in the GFS, then some areas could see issues alluded to by geordiesnow. Longer term and there seems no conclusive signal as to what the 2nd part of this month may hold. Theres great variability in the MJO forecasts, with amplitude remaining low.

There are hints that the NAO may return negative into the 2nd half of the month, although again there is a great deal of variability in the ensemble suite

I think its fairly certain that it will remain warm, and sunny, for most, well into the next week. 

 

MJO really is all over the shot at present, my current best estimation would be heading somewhere towards phase 5 (after a quiet spell with <1 amplitude) temporarily before probably meandering back through the, lets call it the MJO zone of death, into phase 7 to end July, then into phase 8 for August.

 

At the same time we will see AAM ramp up a little in the coming days which should push the GWO towards phase 4 - this would teleconnect well with MJO phase 5 and 7 composites.

 

The ECM has been about the best quite in recent weeks, and the EC32 update tonight might well prove once again to be fairly useful to give us a guide

 

SK

[todd1970]

I've been trawling the charts, and they all seem to suggest that temperatures drop off quite dramatically as you reach a certain line across the north to north east as shown below:

 

 

However I can't see any reason that high temperatures like shown are confined to the area they are. Here are the 850's for the same time:

 

They seem to be fairly high up to mid Scotland, quite equal across the uk. The Dam Line also reveals little:

The 564 line creeps into the the southwest, but that doesn't explain the temp differential in most of the country.

 

Given the position of the high I can't really understand how any strong cooler atlantic winds could have a noticeable effect over so much of England.

 

 

Can anyone enlighten me?

 

Thanks

 

That looks like just the start of the warmth though Kev , by Wednesday or Thursday most of Scotland is in line with the rest of the UK , although a wee bit cooler. 

[Mark Bayley]

MJO really is all over the shot at present, my current best estimation would be heading somewhere towards phase 5 (after a quiet spell with <1 amplitude) temporarily before probably meandering back through the, lets call it the MJO zone of death, into phase 7 to end July, then into phase 8 for August.

 

At the same time we will see AAM ramp up a little in the coming days which should push the GWO towards phase 4 - this would teleconnect well with MJO phase 5 and 7 composites.

 

The ECM has been about the best quite in recent weeks, and the EC32 update tonight might well prove once again to be fairly useful to give us a guide

 

SK

 

The composite for July (phase 5) certainly doesn't make for pleasant viewing!

[Gael_Force]

MJO really is all over the shot at present, my current best estimation would be heading somewhere towards phase 5 (after a quiet spell with <1 amplitude) temporarily before probably meandering back through the, lets call it the MJO zone of death, into phase 7 to end July, then into phase 8 for August.

 

At the same time we will see AAM ramp up a little in the coming days which should push the GWO towards phase 4 - this would teleconnect well with MJO phase 5 and 7 composites.

 

The ECM has been about the best quite in recent weeks, and the EC32 update tonight might well prove once again to be fairly useful to give us a guide

 

SK

 

It looks to be on a quite similar journey to this time last year yet the weather is going to be very different.

 

[Summer Sun]

So far so good from ECM but if the high continues to drift west cloud is going to become an issue in the east

 

[Geordiesnow]

ECM showing an NE'ly flow by mid-week next week which is what the GFS and this afternoon's UKMO run are hinting at which may again lead to more low cloud heading into some eastern areas, western areas should still stay pretty warm and sunny though but there has been some hints of the high heading NW'wards to some extent only for it to back off again so see what happens by tomorrow morning runs. 

Edited July 4, 2013 by Geordiesnow

[Milhouse]

So far so good from ECM but if the high continues to drift west cloud is going to become an issue in the east

 

 

ECM is a bit poor tbh. To see upper temperatures below 10c drifting in can only mean cooler and cloudier weather. The UKMO and GFS are making less of this incursion of cooler air.

ECM showing an NE'ly flow by mid-week next week which is what the GFS and this afternoon's UKMO run are hinting at which may again lead to more low cloud heading into some eastern areas, western areas should still stay pretty warm and sunny though but there has been some hints of the high heading NW'wards to some extent only for it to back off again so see what happens by tomorrow morning runs. 

 

The gfs and ECM at T+144 are quite different though.

 

[snowking]

The composite for July (phase 5) certainly doesn't make for pleasant viewing!

 

Absolutely, the hints are all there from the current medium range ensemble means, with a likelihood of some form of troughing just to the North and East of the UK, still a difference in timing as Tamara illustrated earlier, the current difference in the mean height anomaly outputs around day 10-12 for a transition from the ECM, and around days 13-14 for the GEFS

 

The biggest thing now will be whether we will see sufficient AAM to drive us towards GWO phase 4, or whether we are left meandering around phase 3. If we are left in phase 3 then we may find very little coherence in the medium range - this is the sort of time we could do with the analogues Recretos was looking to create, set against various ENSO states too.

 

All ensemble suites at this stage though do point towards a decrease in T2m, and an increase in Precip, which once again would tally with MJO phase 5 or even 7.

 

 

 

It looks to be on a quite similar journey to this time last year yet the weather is going to be very different.

 

 

True, although much of July 2012 was spent under amplitude <1 conditions, which doesn't always offer a coherent signal . 

 

SK

Edited July 4, 2013 by snowking

[Milhouse]

By T+168 warmer air is beginning to topple back in.

 

[cheese]

GFS looks fine to me - a few cooler days due to a more NEly wind on two days, but mid to high twenties mostly, and 30C is shown at around 192 hours for Yorkshire, so a much better GFS. The high collapses at around 252 hours and low pressure is introduced. 

Edited July 4, 2013 by cheese

[Summer Sun]

Iffy spell mid week from ECM but Thursday its back to normal with the warm uppers sweeping back in

 

[Summer Sun]

T192 sees some slightly cooler uppers just filtering into Scotland but else where it remains very warm to hot

 

 

T216 sees those slightly cooler uppers sweeping down the eastern side of the UK the west remains very warm and locally hot

 

[Tony27]

would it really be cool and cloudy in the east at T120 and T144? although we have north-easterly winds, the high is still over us, these charts really do my head in with their nice orange and red colours but it could be dull and windy, best to stick to the bbc graphics, these 500mb charts give such a false illusion, the charts for today don't look that great yet is was clear and 23c here and barely no wind when we should be in a breezy westerly

[WheresTheSnow]

And also to add to Tony's comments, how far East would you expect to be affected by cloud? The GFS, from having a quick look at, doesn't look too bad at all to me, apart from the late stages of FI where there seems to be a lingering low pressure system over us.