Model Output Discussion 18z 30/09/15

[tinybill]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

all i  say  is fantasy world after  240hr  is looking  interesting  for cold lovers!!!

[Methuselah]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

all i  say  is fantasy world after  240hr  is looking  interesting  for cold lovers!!!

But, for the rest of us, a few days' rain (sleet at a very long stretch) it's looking like murder!

[Costa Del Fal]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

all i  say  is fantasy world after  240hr  is looking  interesting  for cold lovers!!!

Not on that link it isnt. Please could you make reference to charts closer to the now. The things you post barely ever come to fruition. Not meaning to be rude but there is far too much hopecasting at distant charts here. Keep it real and focus more on the near future.

[knocker]

The gfs and ecm in not bad agreement at T120 and both nip the low rapidly SE but the next approaching depression isn't sorted yet. Could well herald a barby

http://www.tropicaltidbits.com/

Edited October 22, 2015 by knocker

[Midlands Ice Age]

Not on that link it isnt. Please could you make reference to charts closer to the now. The things you post barely ever come to fruition. Not meaning to be rude but there is far too much hopecasting at distant charts here. Keep it real and focus more on the near future.

 

CDF...

I thought the same, but I assumed that the GFS perturbations have just updated!

[joggs]

http://www.meteociel.fr/modeles/gefs_cartes.php?code=16&ech=192&carte=&mode=0

 

all i  say  is fantasy world after  240hr  is looking  interesting  for cold lovers!!!

Sorry but disagree,if low and high pressure swapped places on them charts,you have a good point.But all they read is sw winds and unsettled at times with sceuro high and vortex over Greenland and North.Sorry.

[joggs]

Didn't mean to repeat what's been pointed out.sorry

[nick sussex]

The ECM has dropped its 00hrs output and pushes the block much further east. Whether this is the correct trend we'll have to wait and see given its performance over the last week has been dire.

 

The writing was on the wall as early as T120hrs when it phased the filling Atlantic low with low heights over Greenland. Its overall pattern is quite close to the GFS although unusually that's less progressive.

 

The UKMO is quite different from the GFS and ECM at T144hrs and could develop differently given the more amplified upstream pattern.

[IDO]

The ECM has dropped its 00hrs output and pushes the block much further east. Whether this is the correct trend we'll have to wait and see given its performance over the last week has been dire.

 

The writing was on the wall as early as T120hrs when it phased the filling Atlantic low with low heights over Greenland. Its overall pattern is quite close to the GFS although unusually that's less progressive.

 

The UKMO is quite different from the GFS and ECM at T144hrs and could develop differently given the more amplified upstream pattern.

 

No surprise with the ECM de-amplifying; looking at this morning's mean it was more like the GFS output (D10):

 

   This morning's GEM mean:  GFS:

 

As for the UKMO output, more often than not last year we learnt that they were the last to come in line with the general outlook.

 

Looking at the latest JMA they are consistent with the CFS weeklies and the 10 day means: 

 

Support for the UK to be on the boundary of higher and lower pressure. The week 3 & 4 mean suggests an Atlantic breakthrough with a more zonal flow:

 

 

I suppose that the question has always been whether the the HLB'ing of the last 2-3 months will dig itself in and extend into the Winter or that it has just come too early and will pre-empt a tsunami of westerly wind and rain as the PV plays catch up?  We will know in the next 2-3 weeks as if it does start to get going then based on the last few years it takes 4-6 weeks before it calms down (if it does in an El Nino backdrop)?

[ANYWEATHER]

Evening All. the broad outlook is for the Atlantic to be in charge, Yes there is a ridge building across to the North East , but  the Jet stream is too strong. Ive seen this loads of times before, but the Uk is in for  some Stormy conditions  in the near future....   

[Mucka]

That ECM run was very progressive and I thought GFS was pretty fast and flat.

I hope it's wrong (which it probably is) because that looks like it would herald a prolonged spell of wet and windy weather though I guess some wind and rain Autumn is bearable and much better than that pattern setting up in Winter. Chance of some wintry showers for high ground as well as the lows pass through.

 

UKMO has gone the opposite way and offers some hope of blocking while GFS i probably not that far away and sits somewhere between the two. 

It has been very consistent of late over the last few runs out to the mid range whereas ECM ops have really been wobbling around of late.

 

Hoping GFS 18z can get a little closer to the UKMO solution.

[knocker]

Looking at tonight's anomalies just generally confirms what they have been saying for a day or two. That is that in the 6-15 day period there is nothing to suggest anything other than ridging to the NE and a trough to the NW with the Azores HP nudging away to the SW leaving the UK in a general zonal westerly flow which will throw up various scenarios in the detail but nothing particularly noteworthy. One hopes. I appreciate many think the anomalies are a waste of time but as JH often reiterates used carefully, ensuring the major three don't disagree too much over two or three days, and in conjunction with the ops runs, they can be and often are a useful tool. In any case apart from those who have great meteorological expertise most of us are just looking for the percentage play.

EDIT

I forgot, NOAA is above average confidence.

Edited October 22, 2015 by knocker

[Mucka]

"...I appreciate many think the anomalies are a waste of time "

 Le sigh. 

[damianslaw]

Haven't commented much on the models in recent days, largely due to the high pressure hanging around.. however, all are showing a generally unsettled atlantic driven outlook - very typical for late October, one of the most unsettled atlantic dominated periods of the year, so not surprise to see the flip from predominantly settled since early Sept, to unsettled now.

 

However, as others have commented, the pattern is far from standard default raging northern arm of Jetstream affair, its an amplified one, with low pressure set to dig southwards and height building to our NE helped by warm air advection.. we could well see this pattern set in for a bit with temporary azores high ridge development behind each trough formation, whilst all the time those heights to our NE build, then it will be all eyes on where energy in the jet transfers aided by developments over the NE USA seaboard, more energy in the southern arm, would enable those heights to hold the trough in situ and we have a battleground scenario..

 

All conjecture and speculation..

 

I'll not be on the forum much in the net 2 weeks, may dip in and out on occasion.

[Singularity]

Never mind the zonal charts being thrown out for our part of the world tonight - the polar view continues to show a troubled vortex at the tropospheric level. You might think it was getting its act together on the GFS 12z det. run at +252 (below left), with some very low heights encircling Greenland, but by +384 (below-right) it's not looking too clever again as the main lobe displaces toward the UK while a Siberian ridge saunters into the Arctic.

 

 

 

During this time, the strat. vortex at 30hPa follows a remarkably similar path. There seems to be very little lag time between the two levels.

 

 

Temps within cool slightly to +336 with the first blob of -75*C being modelled, but this is actually lost during the following 36 hours. No arguing with the fact that it's more organised in both the two images above than it is at our current point in time, but then it would be downright bizzare not to see it strengthening at the moment, as UV radiation falls away steadily, with less and less to be absorbed by ozone particles and keep the stratosphere from cooling (for more detail on strat. workings, be sure to see Chiono's epic intro post to the 2015-16 stratosphere thread: https://forum.netweather.tv/topic/84231-stratosphere-temperature-watch-20152016/page-1).

 

 

I'm not really seeing enough evidence to call the November pattern one way or the other at the moment, beyond a broad theme of higher pressure east of the UK that may or may not manage to become a high latitude blocking feature in the face of an Atlantic trough that may be anything from lethargic to rampant (though I do favour the more vigorous outcome there in light of the ongoing Atlantic SST anomaly pattern).

[Mucka]

Just had a quick fllck through GFS ensembles and other than the odd one they are pretty flat with a shallow trough. Very little support across the output for UKMO this evening.

If we get fairly zonal set up and it lasts two or three weeks it won't be the end of the world. November 2010 was very wet and mobile through the first half of the month until the Atlantic hit the buffers against a developing Scandi high.

Another month and there will be some cold air proper to  tap into if we get some blocking.

Edited October 22, 2015 by Mucka

[Nouska]

The ARPEGE is very much alone in its modelling of the low at 96 hours - a more elongated and tilted approach. Unfortunately, the 18Z run only goes out to sixty hours so cannot see if maintained.

 

[knocker]

A very rough overview of the latest EC32

 

The 2^nd November a familiar story with trough to the NW and western Med and ridging Scandinavia with heights also pushing into the UK from the SW. Thus surface HP a tad too far east so zonal westerlies and average temps

 

By the 8^th the trough to the NW is now orientated down the North Sea and the other and the Scandinavian ridge has also moved east. Resulting in the LP being more to north of the UK vis the surface analysis but in general with the LP to the NW/N and HP to SW the zonal westerlies continue with temps a tad below average.

 

In a nutshell nothing changes a great deal for the rest of the run except perhaps the low pressure plays a more central role in the Atlantic.

 

So after a period of relative benign westerlies, apart maybe for Scotland, it becomes more unsettled generally as the run progressed with the block weakening and moving east. Temps around average or a little below.

 

The GFS this morning dissipates next week's low over SW Ireland and at D10 has the HP 1050mb away tin eastern Europe

Chart weatherbell

 

Edited October 23, 2015 by knocker

[knocker]

The ecm this morning also disappears the low next week but of rather more interest is it's complicated handling of the mid Atlantic depressions with cyclogenesis afoot.

http://www.tropicaltidbits.com/

 

[MR EXTREMES]

So gem ecm awful and jma gfs and ukmo would be the best for progression towards a colder setup but as it stands possibly November could spend the first week or two with very very mild air and wet especially far west.

But still it must be noted that the Azores heights which I might add gave coldies a headache last winter might aid in lowering pressure to our south although some models have pressure to high so ATM there is just to much blocking so which block will back down first and northern blocking is there,

but It just shows how difficult it is to get a pattern for cold especially easterlys northeasterly and northerly.

[nick sussex]

After a week of poor model performance good agreement on the overall pattern with trough near or over the UK, high pressure to the east/ne.

 

The week has been somewhat of an embarrassment to the ECM which actually called things wrong within T120hrs, this is quite unusual, we've normally seen its post T144hrs output more subject to wild swings and overamplification bias. The week was going okay for the UKMO until last nights output which picked up the overamplified baton and sprinted to the line only to be disqualified for a lane infringement!

 

So both Euros have had a week to forget.

 

In terms of the likely stalemate going forward we often see these scenarios with block to the east and low pressure trying to head east and hitting that brick wall. The ECM does eventually deliver a punch to the block on day ten but I wouldn't assume this will verify, there is somewhat of a bias with blocks and the models can often be too hasty in dislodging them.

 

Indeed we may have not seen the last of the model uncertainty because forcing on the trough is effected by how far north that high pressure to the east gets and also whether the upstream pattern will be flat or more amplified. Current suggestions are that there won't be much help at least initially upstream to help sharpen that UK troughing which of course then would help in disrupting some of that energy towards Iberia and the western Med.

 

So best bet for the timebeing is a rather protracted battle between the trough and block. The De Bilt ensembles are quite good in these situations for looking at the wind flow there because this gives us a clue as to the orientation of the UK trough and how far east it might get. Theres still a large spread in that after day 10 with a decent cluster keeping the wind in from the east/se for Holland which would correlate with the high holding and the trough orientated more n/s or nw/se. Theres nothing that cold showing so this suggests heights will remain relatively high over the Med, colder solutions would only pick up if heights dropped in the Med and the block was orientated more ne/sw rather than north south.

 

We'll see if that changes but that would need more sharpness to the UK trough and high pressure centred further north. As we've seen over the last week the models can make a mess of blocking situations but for the timebeing it looks  a bit of a stalemate.

Edited October 23, 2015 by nick sussex

[NO LONGER POSTING]

T + 192    what happens next can't get past 3 days currently!

 

[Mucka]

We always knew there was going to be a breakdown of the high pressure, the question was how substantial and prolonged would any unsettled weather be.

I'm not sure that has been answered yet.

We are seeing two possible patterns really.

Firstly the slow but  persistent breakdown of high pressure with the Atlantic eventually pushing through bringing a more prolonged spell of milder but wet and windy weather but secondly low pressure systems being stalled by increased blocking to our East promoting WAA through the Scandinavia region and building high pressure here.

This second pattern is really the one I favoured  a week or so ago when I was saying it could be very wet with stalling lows or equally we could quickly find ourselves under a drier cooler continental influence.

 

I think the balance is slightly with the first option of low pressure breaking the block down and riding over the top but I also note that over 50% of GFS 06z ensembles have our weather under some form of continental influence in FI at some point in the run.

GFS control run would be a reasonable overall representation with a continental influence for a while but the Atlantic eventually winning out

 

 

And the operational run is not far behind.

 

So the battle ground is set it seems. Will the Atlantic easily sweep in over the top or will high pressure build and force some undercut?

[Mucka]

Very quiet today?

As we all know the models have been struggling with consistency of late, we always get some run to run variance but these are actually swings back and forth from faster flatter to slower more amplified rather than random variance between runs.

Below is a comparison of UKMO and GFS 120h 12z charts compared with their respective 12z runs yesterday

 

 

So after a couple of days of swinging toward faster flatter today they are moderating back the other way. So given that I think it is likely ECM will be much more amplified this evening and the models haven't quite yet resolved the pattern, at least not so far as the weather we can expect for our small island from day 5+

 

Edit:

Here is the same thing with GEM to show this isn't just random run to run variation

 

 

Does't mean they won't be more progressive again tomorrow though of course. 

 

But if ECM follows suit this evening and charts like tonight's GFS 12z show up we may get an early visit from Santa (That's Mr Murr to coldies   )

 

Edited October 23, 2015 by Mucka

[nick sussex]

More changes this evening with the GFS retrogressing the pattern and the UKMO digging that bowling ball low further south at T144hrs. The UKMO also drives a wedge of high pressure towards se Greenland.

 

The interest would really come at T168hrs to see whether some energy disrupts off that low se'wards as this would then reinforce high pressure further north.

 

Very intrigued now to see what the ECM comes up with.

Edited October 23, 2015 by nick sussex