Model Output Discussion 31/07/14 onwards.

[knocker]

Fair enough, it is odd that as we have got closer to the next week,  the 850s have been diluted dramatically whilst the surface charts have remained pretty similar. Either the northwards push of the warm air is not as strong as it was previously predicted, or something else is going on. 

 

To be honest I haven't looked that closely at that but it could be, as you mentioned earlier, to do with the alignment of the HP. Wasn't it originally further to the east with perhaps greater thicknesses ( higher 850 temps) as the airmass was not modified by the sea. Just a thought.

 

EDIT

 

It could also be that two HP systems have merged with the resultant air mass having different characteristics.

Edited August 30, 2014 by knocker

[Cloud 10]

Which ever way you look at it,a fine warm spell looks to be on the cards for the UK as we head into September with good agreement from ECM and NAEFS ensemble means,although as ever the exact position of the high will dictate who gets the best of it.

 

[IDO]

Recent runs have downgraded the uppers as the placement of the high has been fine tuned. We have therefore lost the Bay of Biscay upper trough and this has downgraded the 850s being advected north.

 

The initial pressure build by mid-week will see the UK high edge east:

 

   GFS and GEM agree.

 

As GFS has been showing for a while the displaced Azores high then cuts off the Atlantic trough and settles over the UK: 

 

 By D10: 

 

GFS is modelling it to have little feed so it sinks SE by T300: 

 

GEM handles post mid-week different. It has the HP pushing the Atlantic trough over the UK and then cuts it off. The UK is then under the surface low for an extended period (4 days+):

 

 

 

Although the GEM is more unsettled, the cut off upper low will feed in warmer temps than the GFS which will have a cooler feed. UKMO seems to support the GFS from midweek:

 

 NAVGEM is closer to GEM: 

 

The GEFS had minimal support for the GEM take, as the mean suggests: 

 

So the GFS looks like the one to follow and that shows about 10 days of mostly settled weather (after the cold front clears Monday). Temps wise, if you take into account the cooler nights, probably average for the south and below further north. The ECM London ensemble mean also suggests average temps:

 

 

Out in FI (after T300) there is a signal for a trough to push into the UK from the NW/W. This ties in with the recent JMA update for weeks 3-4 anomaly:

 

 So September may be a month of two halves; settled then unsettled.

 

 

[bluearmy]

Ukmo and ncep suite look settled whereas gem again finds the cut off upper trough for us. four of the 21 Gsf/gefs members find this feature so remains unlikely but not yet discountable.

Edited August 30, 2014 by bluearmy

[Frosty.]

The GFS 00z op run is very anticyclonic this morning, almost from start to finish, first of all, the azores and scandi high's link up early next week and it becomes increasingly warm and sunny across the whole of the uk, it's not often that can be said. For fine weather fans this is the perfect run, high pressure drifting around but staying in control with temperatures soaring into the low to mid 20's celsius at times and long spells of sunshine..I give this run 10/10

Edited August 30, 2014 by Frosty.

[knocker]

I was looking at the ECM 850s just now and thought hang on there is something wrong here. Started at the beginning and found the quite intense upper low to the SW. Thus the surface highs are pushed NW and east

 

[Captain Shortwave]

ECM adding to the potential cut off low near the UK, but sinks it further west, which results in a draw of warmer air from the south.

Friday still being the day when uncertainty arises.

[mushymanrob]

id love this chart to become reality... of course its unlikely (but not impossible) , potential for some epic thunderstorms on this.

 

[Summer Sun]

UKMO shows high pressure dominating to at least Thursday

 

 

Unfortunately non of the 850's for the charts above are available this morning though it will become increasingly warm as the week progresses with temperatures in the south probably hitting the mid 20's and the low 20's for northern parts of England so all in all quite a pleasant spell coming up with light winds and some decent spells of sunshine

Edited August 30, 2014 by Summer Sun

[Frosty.]

UKMO shows high pressure dominating to at least Thursday

 

 

Unfortunately non the of the 850's for the charts above are available this morning though it will become increasingly warm as the week progresses with temperatures in the south probably hitting the mid 20's and the low 20's for northern parts of England so all in all quite a pleasant spell coming up with light winds and some decent spells of sunshine

On the subject of the 850's (upper air) it's of no concern to me that they are not as warm as previous runs, we can and will generate warm or very warm surface conditions with the synoptics we have for next week, as in winter, we don't need cold 850's for frost to form so i'm very happy about next week, it's the best weather since july by far and for early autumn it's fantastic.

[Summer Sun]

If the ECM ens is right the high will be hanging around for a while once it moves in

 

[William of Walworth]

Does that mean that the intense-looking low shown on the charts knocker posted, is more likely to be an outlier, I wonder?

[bluearmy]

Does that mean that the intense-looking low shown on the charts knocker posted, is more likely to be an outlier, I wonder?

It's not intense - just the way those charts look. The ECM spreads have enough support for the cut off trough dropping close to the sw of the uk to concern anyone looking to discount the gem op.

Will take another few runs to get a better handle on this.

[Polar Maritime]

Hi Will, You can see this little Low Pressure system just to the N/W of Ireland here, It's not a strong feature with the GFS keeping further it West out in the Atlantic atm. A very week affair, Which if materialised would bring a warm dry S/Ely for a time as it passes through sinking South. Certainly not to be discounted just yet.

 

Edited August 30, 2014 by Polar Maritime

[IDO]

id love this chart to become reality... of course its unlikely (but not impossible) , potential for some epic thunderstorms on this.

 

Recm2402.gif

 

Yes we have all become wary (or is that weary) of D10 ECM "blockbuster" charts. Again the op bears no resemblance to the mean uppers at the same time:

 

op:   mean: 

 

Looking at D5 ensembles the op is in the 4th cluster (cluster 1 has only 28% support), with around 17% support (slightly more than GEFS support for a similar outcome): http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!120!pop!od!enfo!enplot!2014083000!!/

 

So as others have suggested it remains a possibility, that is, the cut off upper low closer to our SW/S, but unlikely at the moment. It is a trait of ECM, that when there is uncertainty, it throws out an op that reflects a smaller cluster. However the models took a while to pin down the position of the high so they may struggling with that cut off upper trough/low.

[johnholmes]

Yes the EC anomaly chart had a cut off further east on its issue 00z Friday, this morning, see link below, is not a million miles from the chart mushy shows. Even NOAA 6-10 last evening gave a very slight 'nod' to the idea of a trough SW of the UK for the 6-10 day range.

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

[draztik]

A long way off, but gefs trending cooler into second wk of Sept this morning. As for next week, settled and pleasantly warm. Beautiful!

GEFS surface temp anom days 8-13

Edited August 30, 2014 by draztik

[damianslaw]

Having a quick glance at the models today and longer term.. if the trough digs to our SW as some are suggesting then I wouldn't be surprised to see a retrogression of heights to the NW and a much cooler phase from the north/northeast.. with the trough stubbornly sat over/south of UK.. lots of potential scenarios once we get past next week.

[h2005__uk__]

Are the models fairly certain now about the positioning of highs, lack of southerly flow etc for next week now? Or will it depend on the exact track of Cristobal?

[mushymanrob]

what a difference 7 days makes... (gfs 12z)

 

thurs sept 4

 

 

thurs sept 11

 

 

this colder theme appears to be gathering some momentum for week 2 of september . if it has any credence id have thought the anomaly charts would move towards what the gfs anomaly shows (right of picture)

 

[Cloud 10]

Last 3 GFS operational runs going for a return of the scandi trough  so if your looking for trends in FI....

 

[Weather Boy]

Last 3 GFS operational runs going for a return of the scandi trough  so if your looking for trends in FI....

 

gfs-2014083000-0-240.pnggfs-2014083006-0-240.pnggfs-0-240.png

 

...don't bother.....!

 

Is that what you meant?

 

Very difficult at that range.

[Polar Maritime]

...don't bother.....!

Is that what you meant?

Very difficult at that range.

Hi W.B, Cloud means the the trend reg the opp's during the last 3 runs is for a Scandinavian High. As Draz & Damien says.. A cool down of sorts out in week 2, Maybe from the E/N/E. Lots to be resolved with interest..

Edited August 30, 2014 by Polar Maritime

[stodge]

Evening all

 

A rare chance for me to peruse the operational output from the various 12Z suites.

 

GFS keeps things settled for much of the period albeit with an absence of exceptional warmth as the HP sets up to the NW or North of the British Isles. At T+144

 

http://modeles.meteociel.fr/modeles/gfs/runs/2014083012/gfs-0-144.png?12

 

The key development is the LP over the Azores which forces the HP further north and swings the airflow from the NE or East over the British Isles. Settled yes but probably quite cloudy and disappointing temperatures in contrast to some of the charts from just a few days back.

 

http://www.meteociel.fr/modeles/ecmwf/runs/2014083012/ECM1-144.GIF?30-0

 

ECM not too far away in truth though pressure lower over the UK with the European trough more evident. Warmer conditions from this chart I would contend but with a much greater risk of showers or thunderstorms.

 

http://www.meteociel.fr/ukmo/runs/2014083012/UW144-21.GIF?30-18

 

UKMO a compromise position with a light E'ly flow over the British Isles. Again, settled in the north but a risk of rain to the south and south west.

 

http://modeles.meteociel.fr/modeles/gem/runs/2014083012/gem-0-144.png?12

 

GEM very close to UKMO and in truth there's not a huge degree of disparity between the models. All have HP to the NW and LP to the south or south west so it's an E'ly flow (albeit light) and probably cloud to windward coasts and a risk of showers to the south.

 

http://www.meteociel.fr/modeles/jma/runs/2014083012/J144-21.GIF?30-12

 

JMA very close to the others as well - rare to see such strong agreement at this range as there's usually something different out there but not tonight. 

[Summer Sun]

ECM introduces rain / showers from as early as day 5 especially for the south