Model Output discussion 1st September 00z------->

[damianslaw]

I generally find this time of year the most 'trying' when it comes to model watching, not because it can't produce rapidly changing weather, nor notable warmth for the time of year, just more so that the likelihood of anything notably unusual becomes more difficult and the default pattern is always for an increasing tendency for the typical westerly to gain the upper hand, lengthy high pressure spells,southerlies/ northerlies/easterlies and even cyclonic conditions which tend to all produce greatest deviance from the norm become much harder to sustain themselves against an ever stronger atlantic.

 

Hence its no surprise to see the current high pressure slip being cast aside quickly by the return of the atlantic, what is quite notable though is the pronounced southerly position of the Jetstream - its certainly not in any hurry to settle into its normal northerly path, a recurrent theme since May in the main.. it does mean a cyclonic outlook for the foreseeable rather than the typical westerly, though the models are suggesting more of a typical westerly as we head through the equinox period.

 

Though I always say September is the least interesting month from my perspective, I'm quite liking this one so far, it is giving a bit of everything, a notably cold start, pleasant warm dry conditions thereafter and now what looks like a wet cool windy middle..compared to many recent Septembers which have been woefully tedious and benign.

Edited September 11, 2015 by damianslaw

[ANYWEATHER]

I generally find this time of year the most 'trying' when it comes to model watching, not because it can't produce rapidly changing weather, nor notable warmth for the time of year, just more so that the likelihood of anything notably unusual becomes more difficult and the default pattern is always for an increasing tendency for the typical westerly to gain the upper hand, lengthy high pressure spells,southerlies/ northerlies/easterlies and even cyclonic conditions which tend to all produce greatest deviance from the norm become much harder to sustain themselves against an ever stronger atlantic.

 

Hence its no surprise to see the current high pressure slip being cast aside quickly by the return of the atlantic, what is quite notable though is the pronounced southerly position of the Jetstream - its certainly not in any hurry to settle into its normal northerly path, a recurrent theme since May in the main.. it does mean a cyclonic outlook for the foreseeable rather than the typical westerly, though the models are suggesting more of a typical westerly as we head through the equinox period.

 

Though I always say September is the least interesting month from my perspective, I'm quite liking this one so far, it is giving a bit of everything, a notably cold start, pleasant warm dry conditions thereafter and now what looks like a wet cool windy middle..compared to many recent Septembers which have been woefully tedious and benign.

Indeed, the jet stream is way south this coming week and pretty unusual for the time of year. You will see the disturbed weather on this charts really giving not only Britain ,but Spain and Portugal a rough ride this coming week.....

[Frosty.]

The Ecm 12z ensemble mean shows signs of settled weather returning to the south of the UK from the end of next week onwards as pressure rises. More of a n/s split as time goes on with the north of the UK more likely to stay generally unsettled.

[knocker]

Pretty fair agreement from the ecm, even a suspicion of ridging to the SE, but overall the evolution is along the lines already stated.

 

[Singularity]

That is one vicious little low spinning into the southwest on the ECM 12z operational in five days time.

 

 

This is a little concerning, but at this time only GEM even comes close among the other models, so it's a case of waiting and wondering whether ECM's high resolution is picking up on some small-scale structure that the others are missing? In the case of GEM we're talking about a model that has a habit of making the absolute most of any intense LP potential, so the default position has to be one that assumes it's overcooking the storm.

 

So overall it still seems to be more likely to be a 'rainmaker' than a wind event. At least we're now seeing good signs that high pressure will have a go at following on behind within a day or two. What will be interesting regarding future prospects is whether the jet is adjusted south nearer the time of not, as that would represent a backing down from a typical El-Nino driven tendency to raise pressure over Europe.

[knocker]

As has already been noted looks like a grotty next few days although the timing of this depression is still up for grabs.

http://www.tropicaltidbits.com/

 

 

[knocker]

The ECM take on the midweek low.It's just not on.; a depression over Camborne!

 

 

[Polar Maritime]

Yes knock of all the places, The GFS take on the Mid-week 'Camborne' Low. Not as deep as the ECMWF but it's touch and go..

Edited September 12, 2015 by Polar Maritime

[Summer Sun]

Wednesday looks rather wet for large parts of the UK at this stage Scotland and Northern Ireland hold onto the drier weather till the afternoon

 

 

Temps in the south still make the high teens with the humid air some thunderstorms could break out

 

[Man With Beard]

The ECM take on the midweek low.It's just not on.; a depression over Camborne!

Well the fact that the ECM goes for this on both 00Z runs and 12Z runs is quite concerning. With trees still in full leaf there could be some problems around. Really early to be getting Atlantic depressions like this, it doesn't bode well for early autumn if you like having your shed in the same spot as it was when the season began. In other words, things are looking stormy to me, even if we do get the odd lull.

Hopefully the ECM is up to its old trick of overblowing depressions in the medium term - until all models show the same then its possible we may get away with something milder - but right now I'm seeing storm potential rising and rising

[Nouska]

There's a variety of solutions on the postage stamps, some more severe, others less so.

 

 

The other very high-res global, Arpege, only goes to +102 hours but it looks to have a nasty low swinging in on a, difficult to pin down, fast SSW jet.

 

 

Batten down the hatches!!

[bluearmy]

Some early autumn excitement on the thread!

As an aside, it seems almost impossible to get sustained highish heights in nw Europe over the past few months. that jet just hasn't relented for months. the 'things will even themselves out' approach promises a longish period of autumnal fog and frost or traditional Xmas card winter fare even further ahead. still a chance of an 'Indian summer' second half sept although the latest ECM extended not keen.

In the meantime, we have many Pacific and Atlantic TD's/typhoons/hurricanes modelled on the ens to keep the ens NWP even less reliable than is usual.

[Polar Maritime]

Icelandic Meto take on the Wednesday depression, Based on ECMWF data.

 

 

Edited September 12, 2015 by Polar Maritime

[Polar Maritime]

The 6z shows an interesting deep Low sweep up from the South, Effecting Western parts of the UK/Ireland around the 25th. Been keeping a close eye on it over the past few days, And will continue to...

Edited September 12, 2015 by Polar Maritime

[johnholmes]

There are differences in its depth on the 3 main models although they then tend to agree on its depth and track over the UK.

I wonder which will be correct and also how close will the predicted rainfall totals be for any particular area. For my area GFS suggests 30+mm by Friday on the latest output. I will, as usual, be surprised if the model sticks with a value around that number. Even more I will be surprised if it is within 15% of that value when it actually falls.

Old cynic that I am!

Edited September 12, 2015 by johnholmes

[Polar Maritime]

 I will, as usual, be surprised if the model sticks with a value around that number. Even more I will be surprised if it is within 15% of that value when it actually falls.

Old cynic that I am!

 

Your not the only one John! Yes it will be interesting how the models toy with this feature.

Edited September 12, 2015 by Polar Maritime

[knocker]

In the meantime, we have many Pacific and Atlantic TD's/typhoons/hurricanes modelled on the ens to keep the ens NWP even less reliable than is usual.

 

I wouldn't get too carried away with that blue.  Henri has reached the end of the road and currently there are no global tropical cyclones.

Edited September 12, 2015 by knocker

[Frosty.]

Amazing Gfs 6z, the UK takes a tremendous battering with gales and heavy rain on several occasions, definitely a case of batten down the hatches, nothing benign on this run. We have seen the friendly face of Autumn in recent days but thats all about to change!

[Cloud 10]

Some early autumn excitement on the thread!

As an aside, it seems almost impossible to get sustained highish heights in nw Europe over the past few months. that jet just hasn't relented for months. the 'things will even themselves out' approach promises a longish period of autumnal fog and frost or traditional Xmas card winter fare even further ahead. still a chance of an 'Indian summer' second half sept although the latest ECM extended not keen.

In the meantime, we have many Pacific and Atlantic TD's/typhoons/hurricanes modelled on the ens to keep the ens NWP even less reliable than is usual.

 

06z GFS is an excellent example of the model chaos caused by those features.

[Frosty.]

The Gfs 12z has a much more pleasant low res for the most part with more in the way of high pressure than the 6z but most of high res continues to look cool and very autumnal with bands of rain and occasionally strong winds interspersed by sunshine and showers. There is an improvement by next weekend, especially across the southeast corner with some dry and sunny weather as high pressure builds in across the near continent with temps around 21c for a time in the SE.

Edited September 12, 2015 by Frosty.

[knocker]

Still the Camborne low

Chart weatherbell

 

[knocker]

And the ECM has it a tad deeper

 

[legritter]

Still the Camborne low

Chart weatherbell

Camborne low could be a very potent early autumn storm ,something to keep us on our toes over the coming days on Net weather .will be watching the charts with an eagle eye but dont think it will be till late monday that we will see any track or depth that will give us a clue ,but certainly somewhere in our kneck of the woods will get some newsworthy weather .

great days ahead summers gone here comes autumn then winter ,not many posters about but i,m sure we will see a surge shortly ,    .

[Frosty.]

not many posters about but i,m sure we will see a surge shortly , .

I will be very glad when the winter gang return, roll on winter!

In the meantime, the models show a very autumnal week ahead with lots to keep an eye on with heavy rain and strong winds in the forecast and then like flipping a switch, high pressure returns later in the Ecm 12z this evening.

Edited September 12, 2015 by Frosty.

[bluearmy]

I wouldn't get too carried away with that blue.  Henri has reached the end of the road and currently there are no global tropical cyclones.

Currently knocks, yes but the ens modelling brings in some new activity. It's that time of year!