Model Output Discussions 12z 30/11/16

[bluearmy]

10 minutes ago, Singularity said:

Ah right, thanks ba. There are so many tools these days I sometimes get a bit muddled up 

So I fall back on the model confusion idea, which does appear to have legs based on Nick S' helpful reply (cheers to him too!).

Matt has access to far more than myself (re clusters for one) but the mean eps at the moment at the back end are still a fit for the mean ec 46 for the same timescale. As I mused on Tuesday, the sudden drain of euro height anomolys on the 46 looks a bit odd but we shall see by Friday if the eps are interested in following suit. (By which time a new 46 is available and may not offer continuity!)

[Ali1977]

PV mainly over in Siberia, lets see if Alaskan and Atlantic WAA can head for each other - the potential is there looking at it.

Edited November 30, 2016 by Ali1977

[Frosty.]

Next week becomes mild and changeable on the Gfs 18z, mid teens celsius for some to help stir the growing daffodils!

Edited November 30, 2016 by Frosty.

[lorenzo]

@Ali1977 Course correction before the first day of the forecast issued period - that would be folly...

Keeping an eye on the u increase and current evolution for just how effectively it is programmed to descend.

[ITSY]

1 hour ago, Northern Sky said:

From a glass half full perspective IF the long range models prove to be wrong then let us remember that when they are showing mild weather too! In a way not having a clue what might happen in 10 days time is good thing, then at least you can always hope for something good to turn up. I think it's well documented that the background signals are more favourable than for example last year. So with that in mind let's see what winter brings.

Unfortunately I disagree here. While its of course impossible (and stupid) to put 100% faith in any long range computer forecast (whether cold or mild), mild forecasts are simply more likely to be accurate than not; mild is, simply put, the prevailing weather type in our isles. We live on one of the most temperate islands in the world - especially for our latititude - so we should expect (in my view at least) forecasts which correspond to our average conditions to fair better than those that run against them. That's sad and not what I would want to write, but it is plainly true. 

 Back to the models, and of course they are tempered by MH's change of heart - which I fully understand. Where I agree, for what it's worth, is that the next 7-10 days will determine whether the chances of a *significant* cold spell are likely this December; and, by virtue of the inevitable strengthening of the PV in the coming months, the winter itself. So big things to play for - and much is still possible. 

The final couple of frames on the 18Z pan out as you might predict, with a UK high advecting northward towards Iceland and Greenland. That's all you can hope to see at this range, and interesting to note as part of those trends we talked about. It ain't over till it's over! Look out for the ensembles, see how many others give teaser endings...

Edited November 30, 2016 by ITSY

[Banbury]

2 minutes ago, Frosty. said:

Next week becomes mild and changeable on the Gfs 18z, mid teens celsius for some to help stir the growing daffodils!

Not what HW just said on 21:55 forecast but that's another thread

[nick sussex]

Just reading even more about the MJO and its very uncertain. Okay that's the last I'll say about the MJO this evening!

 There are two centers of activity: 1) Eastern Indian Ocean and western Maritime Continent (Kelvin wave), and 2) West Pacific near New Guinea (Kelvin wave and possibly Rossby wave interaction)

• West Pacific activity is likely destructively interfering with the fast intraseasonal signal that was observed during the past few weeks. Future evolution of the pattern is highly uncertain. 

Extratropics: • Tropical convection can have a substantial impact on the extratropics this time of year, but impacts from the two observed competing signals are opposite each other, so downstream impacts would be affected by which signal is more dominant/has a more robust extratropical response.
 

[Snowman.]

ECM at D10 GFS 18z

Pretty substantial differences, all in FI and all down to change.

[blizzard81]

That PV segment over north east Canada is showing up on all the gfs and ecm ops today at the day 10 range. Not a nice trend imo.

[Rocheydub]

I've read Matt's thoughts, and the lack of posts by SM here speak volumes. But then again, today was just one set of 24 hourly runs. Up and down...

My point is this, there are over-riding signals as GP and Matt have pointed out backed up by Tamara and a few more of the more knowledgable posters. I'm a SACRA. I'm not giving up just because one daily set produce poor charts. We've been here before. I firmly believe this December (last 1/3) will produce a decent wintery spell, for most lowland folk. Not 2009/2010 proportions, because they are once in a lifetime events, but something of note. 

I'm not even having model fatigue yet either. Sure it's not winter for another 67 minutes!!!

[ALL ABOARD]

3 minutes ago, Banbury said:

Not what HW just said on 21:55 forecast but that's another thread

Have you got the link for this be interesting to watch what they have to say ?

[Man With Beard]

This high pressure sinking into Europe is the best hope I can see for deep cold right now. Let the Atlantic trough make it to Scandi and a good chance that the deepening low over Canada might help blow up a high towards Greenland and - possibly - a link up with heights pursuing from the other side.

Good chance of a northerly around mid-month I reckon - it's been the theme of many GEFS ensembles over the past 24 hours. But need that sort spell of mobility to get there.

[Frosty.]

There have already been rumblings that next week could become much milder with a swly airflow. In the great scheme of things it's par for the course in a British winter 

The Gfs 18z looks plausible re next week

Edited November 30, 2016 by Frosty.

[nick sussex]

 The GFS 18 hrs is trying to develop another Scandi high and the NH differences between this run and the earlier GFS 12hrs are laughable. As I've said many a time with the GFS 4 runs a day pick a solution out of a hat and you're guaranteed that it will appear in the lower resolution output.

 

[damianslaw]

Yes quite a change from the models today, which all much more convincing in sinking heights SE, but crucially none are suggesting full on atlantic zonality thereafter, indeed a blink and miss it SW flow, before either a northerly, or an easterly, thanks to ridging over mid east atlantic trending NW, GFS 18Z is showing a diving trough scenario with heights building strongly to the NE.

Definate signals of a trend to colder uppers as we approach mid December is what I'm seeing.

[blizzard81]

Very downbeat in here tonight, myself included. We need some encouraging op runs tomorrow backed up by the ensembles. There you go, it's really that simple

[Paul_1978]

Well well..... South Westerlies at T+201 becomes Westerly/North Westerly by T+225, and a sinking low and Easterly by T+276 and the Atlantic starting to look blocked again. 

Perhaps today hasn't been so bad after all?

[Frosty.]

2 minutes ago, blizzard81 said:

Very downbeat in here tonight, myself included. We need some encouraging op runs tomorrow backed up by the ensembles. There you go, it's really that simple

The Gfs 18z shows a blowtorch swly next week, reminds me of last december

Edited November 30, 2016 by Frosty.

[blizzard81]

Just now, Frosty. said:

The Gfs 18z shows a blowtorch swly next week, reminds me of last december

Fantastic 384h chart though. Ha ha ha, you have to laugh

[Ravelin]

Look, I think we've finally got that retrogressing high everyone was wanting...

All we need now is to get that down to t0, 6hrs at a time. 

[Singularity]

10 minutes ago, nick sussex said:

Just reading even more about the MJO and its very uncertain. Okay that's the last I'll say about the MJO this evening!

 There are two centers of activity: 1) Eastern Indian Ocean and western Maritime Continent (Kelvin wave), and 2) West Pacific near New Guinea (Kelvin wave and possibly Rossby wave interaction)

• West Pacific activity is likely destructively interfering with the fast intraseasonal signal that was observed during the past few weeks. Future evolution of the pattern is highly uncertain. 

Extratropics: • Tropical convection can have a substantial impact on the extratropics this time of year, but impacts from the two observed competing signals are opposite each other, so downstream impacts would be affected by which signal is more dominant/has a more robust extratropical response.
 

Thanks so much for doing what I've not had time to do today, clearly things are even more chaotic than I had gathered from GP's updates.

Let's hope he's right to anticipate the eastward propagation signal coming out on top, and soon enough to help derail downward propagation of stronger zonal winds from the upper strat.

I feel we've all made good progress today in terms of understanding where we're at - if not where exactly we're going 

 

[Frosty.]

2 minutes ago, blizzard81 said:

Fantastic 384h chart though. Ha ha ha, you have to laugh

Looks good for the north sea

[Man With Beard]

I am NOT downbeat tonight! I haven't worried much about the long term forecasts (though much kudos to Matt, great posts on here) and I've just focused on what I can see coming. Study all the D10-D15 information and there's clearly a push of heights likely in the Atlantic. And there's a potential push of heights from the other direction. Can we realistically hope for more than this right at the moment? But the models tell me we are in the game for now. Study those D10-D15 ensembles from the past day and it's clear it's a big theme. And if heights get pushed out of Greenland by the vortex, there's still a chance they'll go over the top of us into Scandi.

A chance I say, not a certainty!!! But can we really hope for more on a D12 chart??

[nick sussex]

1 minute ago, Singularity said:

Thanks so much for doing what I've not had time to do today, clearly things are even more chaotic than I had gathered from GP's updates.

Let's hope he's right to anticipate the eastward propagation signal coming out on top, and soon enough to help derail downward propagation of stronger zonal winds from the upper strat.

I feel we've all made good progress today in terms of understanding where we're at - if not where exactly we're going 

 

You're joking I'm more confused than ever. I read the plethora of MJO related products every week and haven't seen it look that confused for a long time. Shall we now talk about Kelvin waves? That's another story, the real MJO versus the Kelvin Wave versus the Artist formerly known as Kelvin Wave but now called something else! lmao Don't worry my Kelvin Wave obsession was so last year, I haven't decided what this years one will be yet!

[ITSY]

Just now, nick sussex said:

You're joking I'm more confused than ever. I read the plethora of MJO related products every week and haven't seen it look that confused for a long time. Shall we now talk about Kelvin waves? That's another story, the real MJO versus the Kelvin Wave versus the Artist formerly known as Kelvin Wave but now called something else! lmao Don't worry my Kelvin Wave obsession was so last year, I haven't decided what this years one will be yet!

Kelvin Waves 

Shannon entropy 

MJO and the Pacific Oscillation

...what next? Martian tendency? Solar reflex? Disheveled polarity? Magnetic shields? I feel like each one of those has real meaning for this thread...