Model Output Discussions 12z 01/09/2016

[damianslaw]

A change is on the cards, after a lengthy period with a predominantly easterly airstream, by Friday we have a upper low feature developing to our SW cutting off the easterly flow, and turning winds more to the south and south east pulling in milder uppers but much more cloud and wetter conditions, the first spell of frontal rain this month - rare to have to wait until mid month in October.. I doubt it will feel much milder, given the cloud and rain.

Next week, we have a split of sorts between the ECM and GFS, the former is predicting the azores high will gain the upper hand, killing off any atlantic attack, maintaining the jet on a more NE path away from our shores, the GFS on the other hand is making more of the atlantic and a stronger jet kicking aside any azores high ridge development at least for a short time, and instead bringing in fronts from the west on a gusty quite cool wind. As we end the week, both models do show strong heights to our SW shores, however, the GFS isn't showing these ridging NE, unlike the ECM, the outcome then becomes very different. GFS showing a mid atlantic ridge quickly building north towards Greenland and pulling down a potent PM/arctic maritime feed, whereas ECM shows heights building over southern parts of the country which would result in a generally settled spell as we enter the last week of the month.

Jetstream forecast profile would support the GFS evolution, with significant amplification, and us on the cold side of the jet.

What no models continues to show is a raging jetstream or significant low pressure development and gales, the very benign autumn looks like continuing for a bit more time yet. Late October traditionally is one of the most unsettled and most westerly dominated periods of the year, its always noteworthy when we see a settled period or cyclonic/northerly/easterly airstreams instead.. lets see what happens.

Edited October 12, 2016 by damianslaw

[mb018538]

I'd go along with that, not one of the models had showing a raging Atlantic zonal set up as of yet, so we shouldn't expect zonality for a while. ECM looks nice again tonight, though may be out on a limb compared to the other big hitters.

[Frosty.]

There are some very interesting GEFS 12z perturbations as we head towards the end of october and early november with potential polar / arctic maritime shots lining up..if cold weather is your thing of course.

[bluearmy]

Extended ens modelling continue to show very little appetite to take the NAO/AO positive through the next two weeks. Infact the GEFS now modelling a drop off in week 2 after a recovery to neutral value end week 1.

are we potentially looking at an October with a persistent neg AO/NAO throughout  ??

[phil nw.]

The approaching Atlantic low looks like warming things up for much of England and Wales in the next few days as well as bringing the rain and showers with it,cutting off the easterly flow.Further north though it's still looking chilly for a while with parts of eastern and northern Scotland looking particularly cool and wet.

Friday                                                                     Saturday                                                    

  

Saturday's fax

Temperatures in single figures up there compared to mid-teens down south over the weekend.That east/south east wind will likely feel quite raw in the north under that rain. 

 

Edited October 12, 2016 by phil nw.

[Matthew.]

I must say next Wednesday looks pleasant from the ECM. Still not to unusual to me just yet but will be if the pattern develops for the last 3rd of October. 

[phil nw.]

Please stick to model discussion in this thread everyone.

Any speculative comments are for the Winter threads and any off topic ones in here are likely to be removed. 

Thanks all.

[fergieweather]

Just now, Matthew Wilson said:

I must say next Wednesday looks pleasant from the ECM. Still not to unusual to me just yet but will be if the pattern develops for the last 3rd of October. 

Until we see how Nicole resolves, everything is viewed with caution into medium range.

[Frosty.]

The Ecm 12z ensemble mean is looking increasingly settled by the second half of next week onwards as high pressure takes control..very good cross model support for a pleasant spell through late October.

[knocker]

The EPS this evening has HP either just to the west or in situ over the UK from the 19th to the 27th.

[Frosty.]

3 minutes ago, knocker said:

The EPS this evening has HP either just to the west or in situ over the UK from the 19th to the 27th.

Good old EPS..and welcome back knocker, I thought you had left us!

Edited October 12, 2016 by Frosty.

[knocker]

Nicole

[summer blizzard]

I find it interesting that the GFS does very little to remove the surface cold pool to our north east even a week or so from today..

And of course the GFS produces a pretty frigid northerly to end the month (probably some snow showers for Aberdeen)..

 

[Daniel*]

You cannot disdain the GFS consistency to keep churning out charts like this out in the cosmos - but it's very intriguing.

That would be an exceptionally cold northerly indeed for late October temps no higher than 7C at best in the south I would think records would be challenged. I hazard a guess but just fun to look at this stage. Upper air temps wouldn't be out of place in mid-winter to be fair!! 

[knocker]

The next two or three days

The next couple of days will see the pattern change from the easterly regime.Much the same for today with frequent showers in the eastern half of Britain, although becoming drier in the SE later, and with some showers running along the channel coast. Tomorrow starting much the same but Atlantic fronts encroach from the SW late on and that heralds the start of a showery/rain weekend although with the winds veering to the southerly quadrant it may be a bit warmer.

The low pressre to the west tracks north over the weekend and paves the way  for a conduit to open from the deep upper low in northern Canada and the next frontal system to impact the UK Monday/Tues bringing rain and some strong winds.

The rest of the week is a struggle between the HP to the south and the troughs to the north which the former wins leaving most of the UK influenced by high pressure so dry and temps around average.

I can't go and get my Weetabix without mentioning the rapid amplification around the 26th with very strong Atlantic heights and a trough plunging south just to the east of the UK.

Edited October 13, 2016 by knocker

[knocker]

The GEFS anomalies are supporting the HP influence in the 5-10 time frame and also amplification of the Atlantic HP sans the Arctic plunge.

Edited October 13, 2016 by knocker

[Frosty.]

The Gfs 00z shows next week being a week of two halves with the first half chilly and unsettled, cold enough for wintry ppn on the scottish mountains and then around next midweek the trough is pushed aside by high pressure building in from the southwest which settles our weather down, especially across the southern half of the uk and temperatures climb to pleasantly mild / warm levels but then into the following week the high pulls west into the atlantic and we have our first cold shot from the north. The run ends with a large anticyclone just to the NW with a chilly NEly flow well established. 

 

 

[mb018538]

ECM is virtually the same in showing a few unsettled days from the weekend through to the middle of next week, before high pressure starts to build in and quieten things down by the weekend. Could it be our first proper autumn high, with sunny days and foggy mornings??

[Frosty.]

I can't believe I missed the 18z last night, what a cracker of a Northerly..it just shows what could happen with a direct hit, even in October!

[Frosty.]

The Ecm 00z makes less of next weeks trough with high pressure building NE even sooner, it turns into a peach of a run with pleasant sunny days and chilly nights under clear skies but with mist / fog patches forming and a risk of slight frosts..perfect autumn weather develops on this morning's Ecm.

[Kentspur]

5 minutes ago, Frosty. said:

The Ecm 00z makes less of next weeks trough with high pressure building NE even sooner, it turns into a peach of a run with pleasant sunny days and chilly nights under clear skies but with mist / fog patches forming and a risk of slight frosts..perfect autumn weather develops on this morning's Ecm.

Does this mean Nicole will become the diving trough? 

[Frosty.]

1 hour ago, Kentspur said:

Does this mean Nicole will become the diving trough? 

It could be a contributory factor but I don't think its known what impact Nicole will have on our pattern yet, still up in the air..literally.

However, the models are firming up on a transition from low to high pressure during next week but further ahead is currently very uncertain.

Edited October 13, 2016 by Frosty.

[Grimers]

The GFS model and the ECMWF model show a high over SW UK on Thursday and Friday bringing light S winds and cool temperatures to all parts of the UK.

        

Edited October 16, 2016 by Grimers

[johnholmes]

The anomaly charts are varying too much to take them with any degree of confidence. I can only think it is the continued presence of tropical storms/ex hurricanes into the north Atlantic that is causing this variability.

October is well known for being one of only two periods that they are so variable. The other is the change over from winter to summer in the northern hemisphere, really both are season change overs.

[Paul_1978]

One thing for certain is the Jet Stream is currently not really raging, nor is it forecast to.

It seems to be a relatively weak and meandering affair and only on Tuesday/Weds next week (18th/19th Oct) is the Jet Stream going through the UK before it breaks up and dissipates by the 20th.

By Monday (24th Oct) the Jet Stream attempts to power through the UK again, however it starts to significantly buckle so by Thursday we get the mid-Atlantic block established.

That's my assessment anyway - the point being, at no point in the Jet Stream forecast up until near the end of the month, do we appear to have a raging west to east jet, which would appear to mean no Atlantic onslaught on the horizon.