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phil nw.

Model Output Discussions 12z 30/11/16

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1 hour ago, Ali1977 said:

True, next one due out soon so will be interesting to see how it compares.

more spread in medium term, less cold late

pluim_06260_0_00_60.png

Edited by ArHu3

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The EPS mean anomaly out in the far reaches is showing a trough over Alaska and the vortex lobe Northern Canada. Ergo a flatter pattern over the US and N/ Atlantic although the latter does show positive anomalies but the ridging is over the UK from the SW. Thus an upper flow from the westerly quadrant with temps slowly returning to average/ Meanwhile back at the ranch

ecm_eps_t850a_5d_natl_11.png

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The GFS mean keeps the 850's at around +2 from mid-month till around the 19th and doesn't go below 0 like yesterday

gefsens850London0.png

In the words of the weather outlook

170f1b95-e526-4f82-8bf5-593baa06cd0e.png

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As ian posted, the temps drop back after mid month as the high anomolys drift back across the east Atlantic after the several day incursion of Atlantic mobility. (Mainly affecting the nw uk). The euro high anomolys remain fairly intact although weakish as per recent output. as normal heights over Europe are high, anything other than a low or neutral anomoly return to our south is not going to bring deep cold this far. so blocking remains the story but probably never getting far enough north to allow an old fashioned easterly 

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The ensembles have tended to reduce the chances of some kind of cold spell developing mid month with an increasing number of members keeping a west or south west flow over the UK in the 7-10 day range. This can be seen with the more solid temperature gradient through Europe.

EDH1-144.GIF   EDH1-192.GIF   EDH1-240.GIF

Previous ECM ens had shown greater uncertainty with some low heights developing over the Mediterranean with higher heights towards the north/north east. I wouldn't discount this option as the operationals are still toying with these weak higher heights and the potential for a split flow pattern to emerge but the chances do seem to be low in the mid term.

Longer term the GEFs do suggest that we could get another shot at the same route.

gensnh-21-1-240.png   gensnh-21-1-300.png   gensnh-21-1-360.png

Core low heights do seem to recede westwards somewhat which would suggest that we could see some improvement longer term which again ties in with the CFS from a day or so ago with heights building to our north east.

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10 minutes ago, Summer Sun said:

The GFS mean keeps the 850's at around +2 from mid-month till around the 19th and doesn't go below 0 like yesterday

gefsens850London0.png

In the words of the weather outlook

170f1b95-e526-4f82-8bf5-593baa06cd0e.png

That doesn't take into account surface cold even with warm air aloft, I think we would see a return of frost and fog from mid Dec.

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4 minutes ago, IDO said:

Sorry but all I see are two charts showing a similar long wave pattern with differences you would expect re surface conditions and minute. Both have a mini ridge over Europe, a pocket of weak heights over the Bering Sea are, both have spillage of the PV to two main vortices, both have cold on the wrong axis for the UK.

Obviously I didn't mean they were mirror images, at D10 you surely cannot expect that? By D10 I would expect a bit of shuffling between the two but probably a very similar profile.

What are you seeing that I have missed?

I see 2 charts with the odd vague similarity. On the GFS the "two main vortices" are really one with an almost cut off, smaller lobe (which dont stay separate for long in the following frames) ,whereas the ECM has two distinct lobes of equal size. The ridging over Europe is much more distinct on the GFS and the  heights over Bering are not closed on the ECM. The jet in the Atlantic is flatter on the ECM with a huge low. Both of these charts would lead to very different outcomes (looking at the long wave pattern as you suggest)

Need i go on? 

My point is, you may be able to find vague similarities but there is certainly not "good agreement"

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10 minutes ago, Summer Sun said:

The GFS mean keeps the 850's at around +2 from mid-month till around the 19th and doesn't go below 0 like yesterday

gefsens850London0.png

In the words of the weather outlook

170f1b95-e526-4f82-8bf5-593baa06cd0e.png

We are  looking at around a week of milder weather (especially so at night) but if we revert blocked thereafter, the uppers will not be the whole story re surface temps gav. Will be looking to see if the London temps eps graph begins to shorten that milder phase. What I do know (as the ice begins to melt again in my garden) is that it currently feels like a front loaded winter! 

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1 minute ago, bobbydog said:

I see 2 charts with the odd vague similarity. On the GFS the "two main vortices" are really one with an almost cut off, smaller lobe (which dont stay separate for long in the following frames) ,whereas the ECM has two distinct lobes of equal size. The ridging over Europe is much more distinct on the GFS and the  heights over Bering are not closed on the ECM. The jet in the Atlantic is flatter on the ECM with a huge low. Both of these charts would lead to very different outcomes (looking at the long wave pattern as you suggest)

Need i go on? 

My point is, you may be able to find vague similarities but there is certainly not "good agreement"

We will disagree. The net result is that there is no cold pattern, differing degrees of average weather. 

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6 minutes ago, Frosty. said:

That doesn't take into account surface cold even with warm air aloft, I think we would see a return of frost and fog from mid Dec.

It's not all doom and gloom 're a colder feeling second half of Dec..The Gefs 00z mean shows a mild spike through the week ahead but then temps drop to average and then below.

Edited by Frosty.

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13 minutes ago, bluearmy said:

As ian posted, the temps drop back after mid month as the high anomolys drift back across the east Atlantic after the several day incursion of Atlantic mobility. (Mainly affecting the nw uk). The euro high anomolys remain fairly intact although weakish as per recent output. as normal heights over Europe are high, anything other than a low or neutral anomoly return to our south is not going to bring deep cold this far. so blocking remains the story but probably never getting far enough north to allow an old fashioned easterly 

Let's hope that it can still get far enough north to at least allow some frosty clear weather. The alternative surely would be just a continuation of next week's horror show?

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1 minute ago, IDO said:

We will disagree. The net result is that there is no cold pattern, differing degrees of average weather. 

I just think it's misleading to say there is good agreement in the models when there isn't and the ensembles are trending colder (as per Ian's post earlier). There must be a cold pattern emerging somewhere.

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2 minutes ago, Certain kind of fool said:

Let's hope that it can still get far enough north to at least allow some frosty clear weather. The alternative surely would be just a continuation of next week's horror show?

I think high pressure in the vicinity of the UK is where we are headed in the run up to xmas. Probably similar to the weather we experienced last week.

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SOME WORDS OF ENCOURAGEMENT

This is just a brief interim post prior to my next full report. There has been a strong outbreak of pessimism on this model thread during the last week or so which seems to be getting out of hand. Yes, it has been disappointing for many "coldies" like myself to see a change in the "short term" outlook with all the models now showing a period of mild Atlantic weather but there is still a lot to play for.

Before I go on, I must say a few words about the appalling behaviour of a few posters. Some of the comments and criticisms of the professionals and experienced contributors has been wholly unjustified. Tamara, in her post a day or two ago, was 100% right to come to their defence and to reprimand some tasteless posts and posters. There have been a number of attacks on some of the long range forecasters, some of them quite brutal. I am sure that the moderators have had their work cut out removing many of these. There should never be personal abuse or criticisms of any poster – do not attack the messenger. If you disagree with a particular poster, just say so politely and then give your reasons and point out constructively why you have a different view. We should all be completely respectful of each other. The vast majority are positive contributors but a few “bad apples” thoroughly lowers the tone and can be harmful to this site’s reputation.

In my last 2 posts (see pages 202 and 217 of the 4.11.16 model thread) I stressed the need for patience. Last Monday, Judah Cohen (see my page 217 post for extensive coverage and link) pointed towards a temporary warm up during early December and then renewed cold building into Siberia in 2 to 3 weeks and extending out from there as well as more Arctic cold more generally being released down towards middle latitudes. This would tie in with the changes hinted at by some of the models from mid-December onwards. Judging by some of Judah’s recent tweets, he still feels that we are on course for a cold winter. In fact he has some encouragement for European coldies (see his chart and comments posted by “Summer Sun” last night on page 44 of this thread). I will provide a comprehensive report next Tuesday which will include Judah Cohen’s latest update due to be published late Monday evening. I hope that this will excite many of us.

Overall, the set-up for this Winter couldn’t be more different to last Winter which was ruled by a near record breaking El Nino and an exceptionally strong polar vortex and almost relentless roaring zonal jet streams. The mild spell we are about to enter is absolutely nothing like last December. We still have record low Arctic sea ice build-up (the next monthly update on that should be out in time for my Tuesday report). One would expect the record weak polar vortex, that we have had for several months now, to show some signs of strengthening, a period of which we are about to enter. Even if the Arctic ice makes an exceptional recovery, I do not see this having much of an impact until much later in the Winter. So, I strongly feel that this mild spell will be a blip.

The models are still struggling hugely beyond around D8 to D10 with a full array of outcomes. They may not nail down a more definite pattern until the changes to the vortex, in strength and position, can be resolved. I will pick up on this again in my next report. In the meantime, please enjoy this exciting period of model watching and let us all keep completely open minds.

  

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Yep models not showing alot of cold and snow and hence the lack of activity on here the last 3/4 days.One thing i have learnt over last few years is we need lower heights in the Med amongst other things (Nick Sussex taught me that:acute:) and as Crewe cold has consistently alluded too these have been lacking in the models.The next week is pretty nailed on for weather turn milder but i have learnt that a week is a long time in weather and cold weather is still a distinct possibility and temps could still fall below average after this period.We shall see but i am still enjoying watch it all develop. 

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10 minutes ago, bobbydog said:

I just think it's misleading to say there is good agreement in the models when there isn't and the ensembles are trending colder (as per Ian's post earlier). There must be a cold pattern emerging somewhere.

Based on EPS who were late on parade when the upcoming warm sector was forecast for days by GFS. They may be right but the GEfS are not on board yet, moving to average but no consistent clear sign of going below up till D16. I only have the GEFS to go by so that is what I base my views on, as I like to look at clusters and the finer detail which I cannot do with the EPS. Though looking at the GEFS I can see that the axis of cold will change eventually so more chances of PM outbreaks but a signal for anything like a blocked cold with snow, I am not seeing it, and I am not sure the EPS are showing this either.

Edited by IDO

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1 minute ago, IDO said:

Based on EPS who were late on parade when the upcoming warm sector was forecast for days by GFS. They may be right but the GEfS are not on board yet, moving to average but no consistent clear sign of going below up till D16. I only have the GEFS to go by so that is what I base my views on, as I like to look at clusters and the finer detail which I cannot do with the EPS. Though looking at the GEFS I can see that the axis of cold will change eventually so more chances of PM outbreaks but a signal for anything like a blocked cold with snow, I am not seeing it, and I am not sure the EPS are showing this.

A much more reasoned post IDO :good:

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Incidentally, the eps and gefs are trending deep cold heading slowly west from Russia into Europe in two weeks. The eps manage to get >10% probability -10c uppers across Denmark on the 00z suite. Too early to be anything other than a footnote but headed in the right direction rather than see them pulling back east!

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Gfs6z is again poor for cold prospects, there is simply no blocking to force the rampant jet south! That god damn euro high still evident 2 weeks down the line, until we see the back of those heights across Europe we are gona struggle, it just eats away at the clock..

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1 hour ago, IDO said:

We will disagree. The net result is that there is no cold pattern, differing degrees of average weather. 

There is surface cold indicated for the 2nd half of Dec, as we saw recently, with cold dry surface air the temps can drop to minus 9 celsius. The GEFS mean does trend gradually colder after the mild blip.

Edited by Frosty.

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Just my observations, but there are hints appearing in the longer range model outputs, for heights to rise directly to our north, thanks to a deep trough developing over NE Scandi/NW Russia regions, the effect maintains the very amplified flow we have had for quite some time now, and after a week or so of being on the milder side of the polar front jet, we may find ourselves on the colder side, as we see trough disruption developing to our west, with the jet anchored on a more NW-SE path. ECM is showing such a scenario at the 240 hr timeframe, along way off yes.. GFS also suggesting such development.

So we may go from a mild southwest flow, to a colder NW/cyclonic flow mid month, with heights rapidly developing to our NE to the west of the said deep trough over NE Scandi/NW Russia. There is quite a fine line being shown mid month between staying of the milder side of the polar front jet, or colder side, a very fine line indeed... cold pools can now develop rapidly to our NE, and they can be a force to reckon with against what will still be a fairly week amplified jet.

Its been notably dry these past 4 weeks or so here, apart from some heavy rain around the 19-20, a break should be expected, and from a personal perspective, I'd much rather see the mild wet SW flow take over now, than in a couple of weeks time.

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