Model Output Discussion 06Z, 13 Sep. 2013 ---->

[Frosty.]

The GEFS 06z mean is another peach of a run, we get the initial burst of warmth as tropical maritime air floods across the uk on saturday and then very warm continental southerly breezes push into the uk and mixes with the Tm airmass to create a very warm spell with temps into the low to mid 20's celsius for large parts of the uk along with long sunny spells and winds falling light, the outlook for next week is for high pressure to remain in situ with rather warm and sunny weather dominating and a very slack, sluggish pressure pattern, it's only beyond T+300 hours that it might cool off and become less settled, lots of superb weather to enjoy for a good while before any sign of breakdowns...BOOM so, it's either anticyclonic heaven for those of us who are looking forward to another late taste of summery weather or anticyclonic hell for those who want it cool, wet and windy.

Edited September 18, 2013 by Frosty.

[syed2878]

@frosty. Any chance of hitting 30c with those charts u showed, During the incoming setel spell?

[Summer Sun]

@frosty. Any chance of hitting 30c with those charts u showed, During the incoming setel spell?

 

Mid 20's max if it were June, July or August then 30c probably but given the shorter days now and less strength in the sun I doubt it we'd need a Spanish plume to deliver 30c temps now

[Frosty.]

The GEFS 06z control run has a good deal of very warm weather for most of the time actually, unlike the 6z op run, there is no cool down as such, it remains warm at the very least but generally temps look well above the seasonal average which is now about 19c for the south, temps during the next 10 days or so look like being several degrees above average at times and favoured parts of the south and east could be locally hot with temps into the low 80's F from time to time, the biggest feature of the control run is the emphatic anticyclonic dominance which occasionally has to renew itself  but always has control, there is just a mini wobble at around T+240 hours but it's hardly a ripple really, it looks like the last 10 days of september is going to produce a superb spell which may persist into early october, the warmest weather looks like being next week but even beyond that, temps remain well up since the airflow varies between a light to moderate se'ly and sw'ly flow which is never a bad direction, it looks very benign and pleasant further ahead with gentle tranquil warmth and above average sunshine totals with mainly dry conditions but with an increasing risk of overnight mist and fog patches.

Edited September 18, 2013 by Frosty.

[Frosty.]

@frosty. Any chance of hitting 30c with those charts u showed, During the incoming setel spell?

30c is pushing it but 25-28 celsius at the peak of the very warm spell is achievable, especially if the anticyclone becomes centred to the east/se for any length of time, generally from the weekend it looks like low 20's celsius which should then rise into the mid 20's c range, at least across the southern half of the uk.

[Gaz1985]

Decent weekend looking almost nailed on now with strong high pressure, away from Scotland and N Ireland the wind will be light so in any sun it will feel very pleasant indeed. 

 

[snowking]

Well an interesting experiment coming up over the next few weeks, but more on that shortly.

 

First of all lets take a look at the current MJO forecasts from NWP:

 

 

 

We have a gathering consensus for a phase 5-6 progression over the next 5-10 days time, and so after our drier interlude, I would expect a rapidly deteriorating scenario towards something far less settled as we enter the final days of September.

 

In fact, if we take a look at the composites for phase 6 as we progress from September to October, it depicts the likely scenario:

 

 

I know BA was discussing this morning whether we would see more influence from the Western or Eastern trough, well I am with him on this one, I think most likely the Eastern one.

 

The experiment comes thereafter. OLR plots out to days 15-20 generally suggest a rapidly deteriorating MJO signal as tropical convection tails off at around 130E, and so we are unlikely to reach much beyond phase 6.

 

So we are then left in whatever pattern turns out to be the 'base' state without tropical forcing for much of the first half of October. Thus far that base pattern has been a tendency for the Azores HP to ridge (Tamara last night discussed the idea of Settled - Unsettled - Settled, and this is the reason I would agree with such an assessment), and I have seen very little so far to suggest that any sort of seasonal wavelength change has come in to play to alter this....for now at least. It may well be that in the coming 10 days we start to see some huge changes hemispherically, but that is simply conjecture for now.

 

So the theory, at least, is that whatever we see beyond the unsettled spell following our upcoming settled spell could prove to be the default pattern for Autumn when there is little tropical forcing....and looking at OLR plots further out towards days 25-40, whilst of course at such range partially reconstructed data is always going to be open to a certain level of doubt, the signal generally is for a continued rather subdued MJO outlook, with a weak signal perhaps for a short phase 1/2 period through the second half of October, and so for those looking for some more high pressure, lets just hope that period in 15 days time or so turns out to be settled!

 

SK

Edited September 18, 2013 by snowking

[Frosty.]

Fantastic post snowking, your posts remind me so much of glacier point, I cannot think of a higher compliment than that.

[Summer Sun]

With this cold weather now on its final legs we can look forward to another warm spell with temperatures pushing to 25c in the south early next week maybe even a touch higher in one or two spots

 

Temperatures starting to increase

 

 

Mid 20's quite widely in the south and east with eastern Scotland seeing temps in the low 20's as well

 

 

25c in the south by Monday mid 20's widely across the south but cooler further north

 

 

Tuesday sees temperatures dropping but still widely in the high teens for the south

 

 

So one more chilly day tomorrow before Friday sees the first signs of the warmer air moving in

Edited September 18, 2013 by Summer Sun

[Summer Sun]

UKMO remains settled this afternoon

 

[mushymanrob]

Well an interesting experiment coming up over the next few weeks, but more on that shortly.

 

First of all lets take a look at the current MJO forecasts from NWP:

 

 

 

We have a gathering consensus for a phase 5-6 progression over the next 5-10 days time, and so after our drier interlude, I would expect a rapidly deteriorating scenario towards something far less settled as we enter the final days of September.

 

In fact, if we take a look at the composites for phase 6 as we progress from September to October, it depicts the likely scenario:

 

SeptemberPhase6500mb.gif

OctoberPhase6500mb.gif

 

I know BA was discussing this morning whether we would see more influence from the Western or Eastern trough, well I am with him on this one, I think most likely the Eastern one.

 

The experiment comes thereafter. OLR plots out to days 15-20 generally suggest a rapidly deteriorating MJO signal as tropical convection tails off at around 130E, and so we are unlikely to reach much beyond phase 6.

 

So we are then left in whatever pattern turns out to be the 'base' state without tropical forcing for much of the first half of October. Thus far that base pattern has been a tendency for the Azores HP to ridge (Tamara last night discussed the idea of Settled - Unsettled - Settled, and this is the reason I would agree with such an assessment), and I have seen very little so far to suggest that any sort of seasonal wavelength change has come in to play to alter this....for now at least. It may well be that in the coming 10 days we start to see some huge changes hemispherically, but that is simply conjecture for now.

 

So the theory, at least, is that whatever we see beyond the unsettled spell following our upcoming settled spell could prove to be the default pattern for Autumn when there is little tropical forcing....and looking at OLR plots further out towards days 25-40, whilst of course at such range partially reconstructed data is always going to be open to a certain level of doubt, the signal generally is for a continued rather subdued MJO outlook, with a weak signal perhaps for a short phase 1/2 period through the second half of October, and so for those looking for some more high pressure, lets just hope that period in 15 days time or so turns out to be settled!

 

SK

 

...not being funny or disrespectful, but those projected mjo orbits are rather low, weak, so as i understand it arent much use. plus the anomalies for the same period suggest upper ridging, not trough controled as per phase 5-6 composite.

 

i dont know, but theres a discrepancy in what two sets of data are suggesting post day 5/6, actually they are completely different! (mjo vs anoms)

 

 

and the upper ridge looks like it might last

 

 

if subsequent charts agree.

Edited September 18, 2013 by mushymanrob

[snowking]

...not being funny or disrespectful, but those projected mjo orbits are rather low, weak, so as i understand it arent much use. plus the anomalies for the same period suggest upper ridging, not trough controled as per phase 5-6 composite.

 

i dont know, but theres a discrepancy in what two sets of data are suggesting post day 5/6, actually they are completely different!

Hi Rob,

 

Think you might have got a few wires crossed here. Yes the MJO orbits are weak, but you're generally looking at anything > 1SD on the RMM scale for it to have an influence (as ever with meteorology theres a bit of give and take in that figure, but thats the gist of it)

 

In terms of the composites, the phase 6 for September suggests an upper ridge just to the West of the UK, and for October moves that upper ridge even further Westwards, with the trough to the NE responding in kind - again these are never gospel, but it gives the general idea of where MJO phase 6 leaves us around the turn of the month, especially with regards to the discussion from earlier this morning about troughing to the East and West of our incoming high

 

Hope that helps

SK

[bluearmy]

with ref to SK's post above, i would make the following observation.  during july/aug, when there was no strong anomoly showing on week 2 naefs, we invariably got a rise in heights to fill the void come verification. during september, i note that a similar lack of direction trends towards  a trough.  we are all aware that higher heights post sept 21 were trailed two weeks before by naefs. the lack of anomoly now showing for week 2 makes me wonder if we will again see a trough coming into view over the next few days nwp. the current trough first appeared on a 12z gem run which suddenly sent a strong trough nw/se when all the output was trending the flow sw/ne. i wouldnt be surprised to see this upcoming block split, retrogress nw and sink se to allow a trough to drop in.  watch out for a rogue operational run over the  next couple of days - it might not be the outlier it first appears to be !

[lorenzo]

In the most recent guidance on the MJO plots, issued on the 16th, much was made of the propagation signal being scrambled somewhat by Tropical Cyclone Activity.

 

The OLR predicted plot at 120 E bang on with this, Typhoon Usagi, right there.

 

Only point here is the reduced amplitude and also the slower travel round the origin, eastward propagation, may be result of the West Pacific cyclone activity, ironically it also states MJO enhances West Pac Cyclone odds, and reduces Eat Pac odds. So although the plots run  to around the 30th it may be a different set of analogs should the MJO get back on the move. Another one to watch !

[No Balls Like Snow Balls]

It looks like this warm/very warm spell is going to be very brief.

 

The very warm uppers (+10) don't hang around very long. They appear at T72 and then disappear again by T144. So 3 days of warm to very warm temps before they start going down again.

 

 

 

 

 

 

If this is summers last hurrah then wowzies its more like a wet fart.

 

Looking at the posts above it doesn't look long until unsettled weather is back on the menu.

Edited September 18, 2013 by No balls like Snow Balls

[Summer Sun]

It looks like this warm/very warm spell is going to be very brief.

 

The very warm uppers (+10) don't hang around very long. They appear at T72 and then disappear again by T144. So 3 days of warm to very warm temps before they start going down again.

 

Rtavn722.png

 

Rtavn962.png

 

Rtavn1202.png

 

Rtavn1442.png

 

graphe_ens4-1.php.gif

 

Looking at the posts above it doesn't look long until unsettled weather is back on the menu.

 

Before the +10 uppers push back into the south west and southern Ireland at t174

 

 

T192

 

 

Before making inroads across a wider area at t216

 

 

t240

 

 

t264

 

 

 

Before easing way at t288

 

 

+10 uppers could well be back quite quickly after leaving

 

Any lower uppers could be very brief if GFS is correct

Edited September 18, 2013 by Summer Sun

[Mark Neal.]

It looks like this warm/very warm spell is going to be very brief.

 

The very warm uppers (+10) don't hang around very long. They appear at T72 and then disappear again by T144. So 3 days of warm to very warm temps before they start going down again.

 

Rtavn722.png

 

Rtavn962.png

 

Rtavn1202.png

 

Rtavn1442.png

 

graphe_ens4-1.php.gif

 

If this is summers last hurrah then wowzies its more like a wet fart.

 

Looking at the posts above it doesn't look long until unsettled weather is back on the menu.

 

But staying settled well into next week with temperatures above average for late september. Dry conditions, warmer than of late and sunshine on offer. Thats a realistic approach at what looks the outlook for the beginning and mid next week, after that changes could occur with our high losing its grip and trough pushing in from NW. 

 

Looks summery weather to me, albeit we are in late September now! 

Edited September 18, 2013 by Mark Neal.

[Captain Shortwave]

One would think that the settled spell had been abruptly cancelled going by a lot of posts

Anyone predicting any further ahead than Monday may be risking looking foolish. I have to admit guilt for assuming the outlook further ahead. All models this afternoon have increased energy going north east even at 3 days out and hence less energy going south east into the cut off low. How the models continue to ebb and flow might result in quite a wide variety of solutions Tuesday onwards.

GFS/GEM look fine out to day 10, UKMO was better than both up to T144.

Edited September 18, 2013 by Captain shortwave

[Mark Neal.]

One would think that the settled spell had been abruptly cancelled going by a lot of posts

Anyone predicting any further ahead than Monday may be risking looking foolish. I have to admit guilt for assuming the outlook further ahead. All models this afternoon have increased energy going north east even at 3 days out and hence less energy going south east into the cut off low. How the models continue to ebb and flow might result in quite a wide variety of solutions Tuesday onwards.

GFS/GEM look fine out to day 10, UKMO was better than both up to T144.

 

Indeed, there seems to be model consistency (yes i did just say that!) upto at least mid next week for the high pressure to be in control of the weather. But after the end of next week some model runs hinting we could see pressure lose its grip, as we get closer to +144hrs we could see the trough drop in in future output, within the 10 day timeframe onwards. But for now it looks like high pressure is certain to return and bringing some very benign warm conditions! 

[Frosty.]

One would think that the settled spell had been abruptly cancelled going by a lot of posts

Anyone predicting any further ahead than Monday may be risking looking foolish. I have to admit guilt for assuming the outlook further ahead. All models this afternoon have increased energy going north east even at 3 days out and hence less energy going south east into the cut off low. How the models continue to ebb and flow might result in quite a wide variety of solutions Tuesday onwards.

GFS/GEM look fine out to day 10, UKMO was better than both up to T144.

Spot on, the ensemble means look sensational for a prolonged warm and settled outlook, I posted the Ecm 00z ens mean charts and all the way to T+240 hours looked amazing and with power to add, it looked like it could go on into october...BOOM

[Scorcher]

A cracking start from the ECM, looks warmer than the GFS yet again and very similar to the UKMO up to Monday.

[Summer Sun]

+15 uppers moving in on tonight's ECM very good start so far

 

+15 uppers

 

 

Cooler in the north on Tuesday but high pressure dominates still

 

[Frosty.]

The GEFS 12z mean continues the glorious trend from the earlier output, high pressure dominance with just the very far north of the uk exposed to a more changeable atlantic airflow, for 95% of the uk it looks like becoming dry, sunnier and much warmer from this weekend and onwards through next week with the warmest weather across the southern half of england & wales where temperatures could hit 25-27c 80 F, pleasantly warm further north in the low 20's celsius, 21-23c range.

[Summer Sun]

t168 continues with high pressure with +10 uppers hanging on in the south west

 

 

t192 sees the +10 uppers moving northwards once again

 

Edited September 18, 2013 by Summer Sun

[Frosty.]

Tonight's Ecm 12z operational run is still fantastic by late september standards, high pressure builds in and dominates across most of the uk from this weekend until the end of next week with temperatures soaring way above the seasonal average, becoming very warm across the southern half of the uk with temps in the mid to high 20's celsius, the anticyclone is pushed around a bit due to vigorous depressions tracking around the top of it on the polar front jet but for most areas it's a return of summery weather with lots of sunshine and light winds, those uppers (T850 hPa) are sensational for late september, although this run has a wobble at the end of next week, mainly across the north with cooler north atlantic air pushing southeast as the anticyclone very briefly loses some ground as a low pushes across the far north, it literally is a blink or miss it stumble before high pressure would again build in strongly for another spell of sunny and warm weather, even an ecm run that's not firing on all cylinders is still very impressive..hello again summer..