Model Output Discussion - 18z 31/10/15 onwards

[bobbydog]

It's not there on the ecm to which I referred nor on the NOAA 8-14 which is similar ( I know it's a mean but the ecm T360 isn't). Of course I have but it's not well stocked at the moment. Need room for the xmas dafs.

i know you use the means, which is of course a reliable source of the overall pattern. however we can't dismiss a recurring theme within the models. after all, any pertubation is a possible and the mean cannot give us detail for our little island. slight deviations can mean the difference between mild westerlies or cold easterlies...

oh, and a 'stirring' of a greenland high is there on the ECM op-

Edited November 6, 2015 by bobbydog

[bluearmy]

Extended ECM drapes the low anomoly ne/sw whilst the euro high hold on somewhat. Naefs drifts the Atlantic low anomoly slowly se so that it lies to our South. Very different solutions in deep fi

[knocker]

I thought the dashed red lines were positive height anomalies? If so, is that not positive over a good portion of Greenland.

 

Yes but it's pretty weak and compares to s weak ridging NE Canada on the ext ecm to which I referred.

[knocker]

i know you use the means, which is of course a reliable source of the overall pattern. however we can't dismiss a recurring theme within the models. after all, any pertubation is a possible and the mean cannot give us detail for our little island. slight deviations can mean the difference between mild westerlies or cold easterlies...

oh, and a 'stirring' of a greenland high is there on the ECM op-

ECH1-216-1.gif

 

Of course but are you sure it's not in transit as it moves a fair way east in 48hrs and you have selected the the middle chart. Surely not a 'toppling' high.

Edited November 6, 2015 by knocker

[Singularity]

For what it's worth, I'm reserving judgement until the trough is shown to progress so far southeast within the 5-7 day range, as beyond that I've seen too many 'too fast, too clean' transitions being adjusted to something less pronounced for me to place much faith in the longer range in situations such as we have now.

 

On the other hand, I've had a long drink and the N. Atlantic SST profile may help with trough progression on this occasion, so there's no writing off to be done either. The more progressive ECM 12z det. run, and the movement of the ECM ens. since yesterday, have certainly got me thinking as I was starting to be convinced that the trough would end up stuck just west of the Azores in around 9-10 days time with a flow from the subtropics to the UK bringing another round of very mild, murky conditions.

[bobbydog]

Of course but are you sure it's not in transit as it moves a fair way east in 48hrs and you have selected the the middle chart. Surely not a 'toppling' high.

it may be and it is at nearly 10 days but the GFS is showing it as well. as i mentioned in my earlier post, it holds no guarantees for our little island but the general theme is there nonetheless.

[bobbydog]

something stirring in the woodshed?

[damianslaw]

I've been dipping in and out of the forum these past few weeks.. sometimes its good to take a bit of a break, especially when we are under entrenched patterns as we have been all autumn with little day to day variation. Having exchanged the lengthy anticyclonic period that dominated much of September and October, we are now firmly under an unsettled period and one the models show no signs of changing anytime soon - its November and this is very par for the course, this time of year is one of the least likely to offer a settled dry period..

 

GFS and ECM are preety similar in there output in recent runs, both show the euro high only slowly relinquishing its grip on things on the coming days, thanks to changes in the upstream profile over eastern atlantic seaboard, as we head through next week both develop a flattening in the Jetstream profile which in turn enable the atlantic trough to anchor itself over the country as opposed to sticking out to the west this enables a ridge to develop over the mid atlantic and the trough to anchor down into northern Europe forcing the euro high to back SW filtering towards the ridge over the mid atlantic and hence we see heights building northwards towards Greenland.

 

Its a very plausible set up, and a response to developments more generally taking place in the upper atmosphere (read the strat thread) - a stronger faster flowing jet and more typical ridge/trough pattern.

 

I remain dubious about suggestions of Greenland high scenarios, what may happen is we see a cold shot from the NW followed by a typical ridge/trough pattern, but perhaps with quite pronounced polar maritime plunges as we move through the second half of November in a fast flowing picture, good news for Scottish ski season I suppose and overall quite seasonal but no significant cold blocked set up.

 

We shall see..

[knocker]

This morning's gfs run can be best summed up as 'mobile Atlantic'. the whole run sees a succession of depressions running across the UK mainly favouring the northerly track but not always. Thus some wet and windy conditions at times, particularly in the north, but interspersed with calmer and more pleasant interludes especially in the south where the HP is still having some influence. Temps variable around the average with some cooler periods. Three random charts from the run.

http://www.tropicaltidbits.com/

 

[Frosty.]

The Gfs 00z op run shows an Arctic blast sweeping south just beyond mid month with widespread frosts and a risk of snow, especially in the north...more encouragement for coldies, amazing what you can find lurking in knocker's woodshed     

Edited November 7, 2015 by Frosty.

[knocker]

Wasn't lurking for long, ejected to Sweden to make way for a westerly zephyr. As I said previously very mobile.

 

 

[Polar Maritime]

The GFS this morning continues to show a cool unsettled W/N/W flow as we go through next week, Into the weekend and a deep Low is shown to move in off the Atlantic effecting Scotland with Gales even Severe Gales. So a much more unsettled 'seasonal' week coming up than of late. Into the end of the run, And the GFS still seems to be toying with the Jet buckling South at times, Pushing colder air in from the N/NW. As to what extent this will effect the UK remains to be seen, But certainly after a long period of above avg temps a cooler trend continues as we head deeper into November towards the start of Winter. 

Edited November 7, 2015 by Polar Maritime

[tinybill]

The GFS this morning continues to show a cool unsettled W/N/W flow as we go through next week, Into the weekend and a deep Low is shown to move in off the Atlantic effecting Scotland with Gales even Severe Gales. So a much more unsettled 'seasonal' week coming up than of late. Into the end of the run, And the GFS still seems to be toying with the Jet buckling South at times, Pushing colder air in from the N/NW. As to what extent this will effect the UK remains to be seen, But certainly a cooler trend continues as we head deeper into November towards the start of Winter. 

with all this rain we are  now  geting  next thing will be the return of the floods in the  uk. looking at the  models  this  no let  up in sight

[winterof79]

Something a little more seasonal on the horizon.

The mild mush looks like having the life squeezed out mid month.

Looking good Northern Hemispherically compared with last year too.

[Polar Maritime]

with all this rain we are  now  geting  next thing will be the return of the floods in the  uk. looking at the  models  this  no let  up in sight

 

Yes Tiny, A much more mobile period coming up. It should actually feel like Autumn! 

[knocker]

The GEFS 6-10 anomaly this morning has LP alaska, ridge Labrador Strait, positively tilted trough Iceland/mid Atlantic and HP to the SE of the UK. Ergo zonal flow with depressions nipping along but much of a N/S split over the UK.

 

The 11-15 has ridge Greenland and weak trough north of the UK. Result is retaining the zonality but with the ebbing of the HP influence to the south unsettled for all of the UK with periods of wet and windy interspersed with drier interludes. Temps varying around the norm in this mobile scenario.

 

[Cloud 10]

with all this rain we are  now  geting  next thing will be the return of the floods in the  uk. looking at the  models  this  no let  up in sight

 

Yes,looks like a very wet week coming up,especially in the West/North-West,with Cumbria looking to get 6+ inches of rain and parts of Wales possibly more.

 

Western Scotland also in the firing line as usual from this setup.

 

 

 

Some rather peachy looking GEFS members this morning as well...

 

[bluearmy]

The GEFS 6-10 anomaly this morning has LP alaska, ridge Labrador Strait, positively tilted trough Iceland/mid Atlantic and HP to the SE of the UK. Ergo zonal flow with depressions nipping along but much of a N/S split over the UK.

 

The 11-15 has ridge Greenland and weak trough north of the UK. Result is retaining the zonality but with the ebbing of the HP influence to the south unsettled for all of the UK with periods of wet and windy interspersed with drier interludes. Temps varying around the norm in this mobile scenario.

Extended ECM ens retain the Greenland/ne Canada high anomoly but don't lose the euro one like naefs does. Same stand off as yesterday, the ECM ens pre day 10 firming up on a greeny upper ridge but with the euro ridge retained, a west based -NAO seems assured if that plays out.

[SLEETY]

Extended ECM ens retain the Greenland/ne Canada high anomoly but don't lose the euro one like naefs does. Same stand off as yesterday, the ECM ens pre day 10 firming up on a greeny upper ridge but with the euro ridge retained, a west based -NAO seems assured if that plays out.

so no one knows what going to happen yet then you mean

[Summer Sun]

A very mild spell coming up with temperatures in some parts getting towards 18c for some places in southern England temperatures in Scotland though, are no where near those levels infact for most of next week they struggle to get into double figures

 

 

As we get towards mid week temperatures are starting to ease back down towards the seasonal average for northern parts of England and by Thursday these more average temperatures reach the south

 

 

The week ends on a more average note, but just look at some northern parts of Scotland barely make it above 3c any precipitation here would be turning wintry

 

 

Into next weekend and the mild air has another go from the south west sending temps back into the mid teens again, though northern parts of Scotland barely make it above 3c so always staying colder here

 

 

The weekend ends on a very clear north, south spilt the south having temps in the mid teens more average midland north wards though again parts of northern Scotland are colder

 

 

The final chart I'm going to post is a week, Monday which shows a return to lower temps for all parts

 

 

So a bit of everything over the next week or so very mild at first for England and Wales before becoming more average around mid week then its the south, mainly which sees brief returns to something milder before fresher air sweeps that away

[snowking]

Extended ECM ens retain the Greenland/ne Canada high anomoly but don't lose the euro one like naefs does. Same stand off as yesterday, the ECM ens pre day 10 firming up on a greeny upper ridge but with the euro ridge retained, a west based -NAO seems assured if that plays out.

 

It's an interesting one.

 

The first thing to say is that in the mid term (days 4-7) there looks to be remarkably high confidence in the ensemble suite with just a single cluster.

 

Beyond this though there is huge divergence. The strong NW sector high anomaly in the mean is skewed somewhat by the remarkably strong height anomaly of a relatively small cluster, but it's a possibility nonetheless, especially against the backdrop of a rather large spread and, resultantly, a large number of clusters beyond day 8.

 

Overall not a great suite to draw too many conclusions from in the longer term, but a rather agreed upon dip in T2m next weekend before chaos ensues.

 

SK

[Ali1977]

Latest from METO still suggesting average temps, this makes me think the high pressure forming near Greenland in around 10 days doesn't quite have the set up to deliver anything decent from the North this time...Still making for good model watching.

[Liam J]

The dreaded Euro high making a come back on the 6Z with a very mild SW flow... Was hoping we'd seen the back of charts like this..!!! 

 

 

 

[Singularity]

 

Look how the positioning of that intense low in 7 days time has changed between the 00z (left) and 06z (right) det. runs.

 

The behaviour of this feature, as it exploits an unusually large temperature gradient (via enhanced jet stream) between the Atlantic and Europe, looks to be critical in determining how much the Euro High is flattened and forced to back west into the Atlantic - hence the balance of power in the 10-14 day period between higher pressure to the NW and the ridge across Europe.

 

The GFS 06z det. has quite suddenly moved toward what the ECM det. was showing up until yesterday's 00z effort. Yet ECM (somewhat typically) has moved to the other extreme, being extremely progressive with the whole trough complex moving to between Iceland and Svalbard by day 10 and nothing much being left behind. This is largely a result of there being no secondary low associated with the intense system in 7 days time:

 

 

In other words it's a very 'clean' solution - making it one where you have to wonder if the atmosphere will really allow things to be so straight forward. Complications usually arise one way or another.

 

Seeing this intense system in the models serves as a reminder that, with the colder than usual central-North Atlantic and warmer than usual Europe, the ingredients are there for a particularly strong jet stream with some monstrous storms developing along the boundary in the coming weeks, as the upper atmosphere becomes increasingly favourable as well.

 

I'm starting to think we could see the sort of thing that turned up at times in the early 90's - a kind of 'super zonal' with immense storm systems tracking near Scotland while high pressure over the Azores and Europe serves only to enhance the pressure gradients and hence wind speeds.

 

For example, scenarios like this seem possible:

 

 

...but the Euro High may at least tend to save us from the likes of this:

 

 

That one was a real monster, for England and Wales it's arguable the worst storm of the past two decades in terms of the extent of severe impacts. 

[Frosty.]

I just had a look at the GEFS 6z perturbations and from a coldies point of view there is plenty of potential for polar / arctic maritime incursions during the mid november period and even beyond, I haven't shown them all and there are others with cold air poised just to the north of the uk so although we are still stuck with very mild mush for a little while longer, it looks like cooling off closer to average later next week, especially further north and I think there is good potential for our first cold snap / spell during mid / late november.  

Edited November 7, 2015 by Frosty.