Model Output Discussion - 31/8/14 Onwards.

[knocker]

At least there are some changes with tonight's anomalies not that they portend a more active surface synopsis. Basically the HPs are not so intense and they have moved east. The HP over North America is now in the western Atlantic and the other east of the UK. The Atlantic trough has gone. Progressing this further the HP covers the mid Atlantic accompanied by a weak jet,

 

On the surface slack HP stretching over the Atlantic with the cold air way north so fairly settled weather for some time to come with around average temps.

 

 

[johnholmes]

yes but the NOAA anomaly of heights is 90 or less DM, only the EC version takes it higher than this away from the UK. How much that will distort the otherwise westerly flow is very difficult to decide, if any in my view. If we look at the contours predicted only, then there is little in the way of ridging other than to the east of the UK. So how effective will the ridging/+ve heights in this area be in keeping the fairly settled weather for the UK. Looking at the trend over the last few days and, as a result of the main wavelength, measured trough to trough, not being quite long enough, the charts over the last 3 days have shown a very slow movement east of this ridge. Will this continue? The 8-14 as it often does smooths out things even more so it is not that clear. But probably the form horse is for it to become slowly less settled away from the already not really settled far NW of the UK.

 

For simplicity then not that different from the current Met O 6-30 day forecast.

[Frosty.]

I noticed there is a risk of thundery showers spreading up from France early next week into the south as the jet briefly buckles and we import continental warmth to boost our already warm conditions. Later next week looks settled again as high pressure intensifies across southern UK. The northwestern corner of the UK is likely to be exposed to Atlantic conditions with stronger winds and heavy rain at times.

[bluearmy]

And on it goes............ However, that's two successive GEM runs that create pretty significant arctic blocking through week 2. Are we in the south about to finally witness the onset of real autumnal weather or will our extended summer continue.

[knocker]

I noticed there is a risk of thundery showers spreading up from France early next week into the south as the jet briefly buckles and we import continental warmth to boost our already warm conditions. Later next week looks settled again as high pressure intensifies across southern UK. The northwestern corner of the UK is likely to be exposed to Atlantic conditions with stronger winds and heavy rain at times.

 

Are you saying there is a connection between the jet buckling and thunderstorms spreading from France?

[Polar Maritime]

And on it goes............ However, that's two successive GEM runs that create pretty significant arctic blocking through week 2. Are we in the south about to finally witness the onset of real autumnal weather or will our extended summer continue.

 

Yes as you say around the 5th-7th shows a change to a more Atlantic driven pattern. The GFS also keeps hinting this to, With Hight's pushing up into Greenland driving Lows South of the UK. A long way out, But a signal is certainly there. 

 

Edited September 26, 2014 by Polar Maritime

[Polar Maritime]

Are you saying there is a connection between the jet buckling and thunderstorms spreading from France?

 

The Jet buckling can certainly aid to push warm air North, All depending on where the "kink" takes place, But is only one part of the ingredient required amongst many others that have to fall in place to produce Thunderstorms.

Edited September 26, 2014 by Polar Maritime

[shaky]

The Jet buckling can certainly aid to push warm air North, All depending on where the "kink" takes place mind..

ecmwf is showing two little lows coming up from france sunday night and Monday morning in the warm humid airmass!!!are you on about those?

[Frosty.]

Are you saying there is a connection between the jet buckling and thunderstorms spreading from France?

Yes, as polar maritime said on previous page, couldn't have put it better  

Edited September 26, 2014 by Frosty.

[Polar Maritime]

ecmwf is showing two little lows coming up from france sunday night and Monday morning in the warm humid airmass!!!are you on about those?

 

No, Take a look at the charts with-in my post, ECMWF only goes out to the 5th. Im not looking at small detail.. Only the overall movement of the N/Hemisphere and the PV out in week 2 as Blue also commented. This is only a week signal atm, But it's there.

Edited September 26, 2014 by Polar Maritime

[Captain Shortwave]

I'm going to remain slightly dubious about any pattern change as in general the pattern remains with low heights over the Greenland/Northern Canada region with the Siberian sector looking a lot calmer. The GEM manages to wedge an area of heights between the Canadian low and the one currently over Greenland/Iceland which would subsequently head our way. 

To be honest it's more than likely that we will continue to see a continuation of the current pattern of cold air flooding south into the Atlantic with frequent ridging north east from the Azores towards Scandinavia. Simply put that gap on the GEM will probably not exist come T0, though the upcoming ridge shown over the states might be enough to drag more unsettled weather further south, though for the likes of me down in the south I suspect there will be very little threat of rain again.

[knocker]

Yes, as polar maritime said on previous page, couldn't have put it better  

 

Very tenuous and it's academic any way as the jet is to the north of the UK on the 06Z GFS

[knocker]

The ECM for the beginning of the week. The jet is wizzing around these two systems passing over Scotland allowing the warm air to circulate in the southern UK. That's my story anyway.

Edited September 26, 2014 by knocker

[Gibby]

Good morning. The GFS Ensemble Pack are the highlights of this morning's 00z output. My thoughts can be read here.

 

http://www.norton-radstockweather.co.uk/NEW-Model-Analysis(2859336).htm

[Summer Sun]

Away from NW Scotland UKMO remains warm and settled this morning, NW Scotland settles down eventually

 

[Frosty.]

The GFS 06z op run shows a lot of very warm weather during the next few weeks with predominantly SE'ly winds drawing increased warmth from southern europe into the uk with temperatures soaring well into the low to possibly mid 20's celsius range across england & wales but rather less warm further north, even as we head towards mid october we could still be talking about very warm weather.

 

Let's start with the reliable timeframe, high pressure this weekend covering southern uk will bring fine and warm conditions after the clearance of overnight fog patches, the sun still has enough punch to burn any stubborn fog patches away whereas by mid october onwards, it won't. Early next week our high relaxes it's grip and a more unstable southerly flow pushes scattered heavy showers with a risk of thunder into southern england with a few heavy showers breaking out due to the increased humidity, there is a risk of some thunderstorms pushing north out of france towards the south and east of england on monday evening and overnight but then tuesday onwards looks fine and warm again, more unsettled to the northwest. High pressure migrates into scandinavia which strengthens the block to the NE.

 

There is then an interesting development, a trough well to the northwest of the uk breaks away from the parent trough and slides south to the west of the uk and ends up to the southwest, this reinforces the warm continental airflow across the uk and keeps pumping very warm air our way, should this occur, it's a very sustainable pattern with HP to the NE and LP to the SW, locked in pattern springs to mind. So whereas yesterdays 6z showed cold Easterly winds in FI, this run shows very warm S'ly to SE'lies.

[Blessed Weather]

Something that caught my eye from the ECM and GFS model outputs this morning was the possible build of cold air in Russia starting at the end of next week.

The 850 hPa output from both models for 1^st Oct shows a plunge of -5 uppers coming down into Russia on the eastern flank of the Scandinavian High.

 

ECM:   GFS:

 

By the 6^th Oct both models are still broadly in agreement that the resultant cold pool is still there and indeed has crept West, by then knocking on the door of Poland. 

 

ECM:   GFS:

Very much FI but should this happen it will certainly accelerate the cooling of continental Europe during early October.

[knocker]

A glance at the ECM weeklies and global anomaly.

 

[Frosty.]

Biggest hint yet from the Experts (Met) that a more generally unsettled, cooler and windier further outlook is on the way and in the gaps between depressions, cold enough for overnight frost, nice to read an update which suggests real autumn won't be long before it gets here, in the meantime. the models show the far northwest gets an early taste of this and eventually we all will.

Edited September 26, 2014 by Frosty.

[johnholmes]

this is what the Met O actually printed both today and you can look back at earlier outputs on the link Stu regularly posts

https://forum.netweather.tv/topic/64157-meto-uk-further-outlook/page-89#entry3045865

[Summer Sun]

UKMO shows high pressure building in strongly during the second half of next week forcing a deep low to head for Iceland, the exception to the settled weather at times looks to be the north west of Scotland where your closer to that low

 

[Captain Shortwave]

After a rather warm and at times cloudy weekend and beginning of next week, we will see a cold front push down midweek to bring brighter and clear conditions before we go through all of this again as the Azores high builds north eastwards to sit slap bang over the UK.

Good agreement there from the UKMO and GFS.

The GFS drifts the high eastwards with another attempt to pull up some drier and very warm air from the continent.

This repeating pattern looks set for another week at least if these two models are correct.

 

GEM follows suit tonight

Edited September 26, 2014 by Captain shortwave

[phil nw.]

Signs that week 2 will see a change with a trough developing in the eastern Atlantic and moving towards the UK.

Hints of this on last nights CPC8-14day chart and showing today on the later GFS mean

http://modeles.meteociel.fr/modeles/gens/run/gensnh-21-1-192.png?12

It looks like as our current high moves east the Atlantic jet buckles south cutting through the present Atlantic high pressure belt.

As the Captain says above perhaps another week of relatively quiet and dry weather to come but then around days 8-10 more unsettled conditions may well be showing up.

[IDO]

JMA's recent update keeping higher pressure in charge for a couple of weeks: D10-16 (from 24th): 

 

Even the week 3-4 anomaly shows no sign of an active Atlantic: 

 

The GEFS suggest that there are background noises and the 12z showing after D5 lots of uncertainty with the pressure graph showing lots of scatter:

 

 

Looking at the D10 individual members no real signal with even support for the GEM D10: 

 

For a few runs the GFS had been showing some strong northern blocking but the 12z has a lot less negative AO:

 

12z    0z: 

 

CFS consistent still at throwing October mean anomalies similar to the latest (no Atlantic flow there): 

 

Bearing in mind the reluctance for the pattern to change I would have to stick with the status quo till a clear signal arrives; however a more unsettled scenario cannot be ruled out on tonight's run.

 

 

[ANYWEATHER]

The Benign  Autumn continues for at least another week. Ecm is keen on a change at day 10 rather than Gfs. As recently though we have seen this scenario many times with a big pattern change. The big pattern change will happen sooner or later, but for now some nice and quiet for is likely......