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phil nw.

Model Output Discussions 12z 30/11/16

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Just now, mountain shadow said:

Did you read GP's and Singularity's posts on Angular Momentum projections?

Yes I read every post, I'm just describing what the Gfs 6z shows which is rather mild.:)

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Just now, Frosty. said:

Yes I read every post, I'm just describing what the Gfs 6z shows which is rather mild.:)

Erm yes, but you caveated that with "so much for background signals". The background signals are of course the longer term teleconnections that GP and others refer too. Those background signals are still there but as I read it, the models are not picking them up, due to incorrectly predicting the angular momentum.

I suppose we will know in a week whether the models or the pros are wrong.

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Just now, mountain shadow said:

Erm yes, but you caveated that with "so much for background signals". The background signals are of course the longer term teleconnections that GP and others refer too. Those background signals are still there but as I read it, the models are not picking them up, due to incorrectly predicting the angular momentum.

I suppose we will know in a week whether the models or the pros are wrong.

I just treat every run on its merits, my comment regarding the background signals was light hearted mocking at the rather mild looking outlook..that's all! of course I would like to be describing wintry op / ens mean but I can't at the moment because it's not showing anything.:)

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2 minutes ago, Frosty. said:

I just treat every run on its merits, my comment regarding the background signals was light hearted mocking at the rather mild looking outlook..that's all! of course I would like to be describing wintry op / ens mean but I can't at the moment because it's not showing anything.:)

Aye, Frost, I mean Karl.:D

We have a good opportunity to put the 'background signals' to the test: will they be strong enough to dominate the foreground signals or vice versa... Or will there be a Mexican stand-off?

The Good, The Bad and The Ugly perhaps?:bomb:

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GP a question? Reading between the lines are you suggesting that the outputs are too flat and that the AAM should really be increasing and therefore increasing the chances for blocking?

Not sure if you saw the MJO update but this does seem to tie in with what you're saying:

• 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.

• 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.
 

Now how do we discern which of those two signals is likely to come out on top? Doesn't the KW help to keep the MJO moving given the interplay between both. In terms of the Rossby Wave versus Kelvin wave aren't we seeing a type of tug of war here, on the one hand the RW moving west and the KW moving east so this is indeed the conflict.

I think the summary below that I've seen is an easy to understand way of describing this interplay for newcomers to RW, KWs and the MJO.

Several hypotheses show that the MJO convection would be accompanied by Kelvin waves in West moving together towards the East. The first Kelvin wave is interrupted by a Rossby wave leaving behind it some time the quasi-stationary convection until another Kelvin wave comes in. Then a second Kelvin wave heading eastward until it is again interrupted or slowed by the Rossby wave. These observations, seems to suggest that Kelvin and Rossby waves interacting with each other can play a key role in the mechanism of propagation of the MJO.

Edited by nick sussex

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12 minutes ago, mountain shadow said:

Did you read GP's and Singularity's posts on Angular Momentum projections?

I think a lot of projections have been mused over for the past month ete which is fair enough but its not giving anything but a guide at best.Id agree with frosty in regard to the outlook looking pretty average fair over the next 10 days or so.I still think the nhp isnt as per usual but maybe us in the uk arnt going get a break ie getting any good 850s in and the decent wintry weather.The atmosphere is in such a state of flux that anyone trying to nail down any detail is a very brave guy!!!

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14 minutes ago, Frosty. said:

Yes I read every post, I'm just describing what the Gfs 6z shows which is rather mild.:)

Frosty - the 06z is one run !! The models are up and down at the minute and every winter is the same. Knowledge is power and no-one has a week to a fortnight forecast in advance nailed never mind a winter forecast. Some of the guys on here are very knowledgeable and are trying to show what signals are being shown. It just shows how a weather event 1000's of miles from our shores can impact these signals. I recall recently the storm for southern England - the met office still weren't sure of its track 12hrs beforehand and even then it still tracked further south than forecast impacting more severely northern France. So i fail to understand why people quote off one run rather than try and put the pieces together and look for a trend as to what is more likely to happen.  

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7 minutes ago, warrenb said:

Meto must be confident as they are  tweeting their blog again, highlighting a cold start to winter.

I think there will be a rapid flip in the models soon.

I'm sure I have read and seen similar posts like this one for quite a while now and it just not quite happened unfortunately. We have had quite a few missed opportunities now that you wonder whether the tide is turning. 

Grimers is right when he says we just have to ride out the current weather for next week, the high is now forecast to breakdown significantly quicker and we could be under the tropical maritime airmass from mid-week onwards, how long will this last for is anyones guess at this range.

Still for some members, they may think this is a good thing as we are getting some actual weather as there was moans and complaints about the high forming and doing very little before it even fully begun!

The only thing that encourages me at this moment in time is we are seeing bouts of the PV dropping into western Russia, its fair to say this occurance has occured less frequently in recent years so we just got to wait and see if it will ever head westwards to our shores.

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Frustration setting in for many as the cold is always 2 weeks away. Now the mid dec period is also looking unlikely.  I see the TWO winter forecast has gone for a "cold core" or middle part of winter. Let's hope the EC 45 sticks to its guns tomorrow or I might invest in Prozac! 

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Historically, when the pros go against the models it is my reflection that the pros tend to win. Having said that, such situations almost always entail model support for cold and snow, and pro support for mild, default, conditions. Now that the shoe is on the other foot, I'm not so convinced - though I would love for the pros to carry on their streak. Matt's insightful posts would suggest an increasing layer of doubt beginning to descend though. Lets await the 46 dayer tonight which is arguably the most anticipated for months if not years. I still believe that unless the models flip in the next 7 days, our window for mid-late December will have passed. 

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11 minutes ago, johnny1972 said:

Frosty - the 06z is one run !! The models are up and down at the minute and every winter is the same. Knowledge is power and no-one has a week to a fortnight forecast in advance nailed never mind a winter forecast. Some of the guys on here are very knowledgeable and are trying to show what signals are being shown. It just shows how a weather event 1000's of miles from our shores can impact these signals. I recall recently the storm for southern England - the met office still weren't sure of its track 12hrs beforehand and even then it still tracked further south than forecast impacting more severely northern France. So i fail to understand why people quote off one run rather than try and put the pieces together and look for a trend as to what is more likely to happen.  

In fairness, previous GFS runs and the ECM runs show broadly the same mild outlook for the medium term, so it is accurate using every sensible medium range model available.

I don't think there is anything to worry about just yet, as the tweet from IF showed, the blocked scenario is still the more likely, but the confidence in it took a hit the past day or so.

 

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3 minutes ago, Geordiesnow said:

I'm sure I have read and seen similar posts like this one for quite a while now and it just not quite happened unfortunately. We have had quite a few missed opportunities now that you wonder whether the tide is turning. 

My understanding from having read carefully the posts of the more experienced/better informed posters is that the daily models have not been expected to resolve the situation suggested by the background signals YET - though we should be soon approaching that time wrt mid-December. Until then it difficult to remain calm while the daily model outputs roll out. There seems to have been a definite outbreak of Pre-Midwinter Tension on the forum of late!

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3 minutes ago, Tim Bland said:

Frustration setting in for many as the cold is always 2 weeks away. Now the mid dec period is also looking unlikely.  I see the TWO winter forecast has gone for a "cold core" or middle part of winter. Let's hope the EC 45 sticks to its guns tomorrow or I might invest in Prozac! 

haha me too.What i find odd recently is that folk say look out for the big changes in fi ete regarding the meto ete talking of a change mid dec to a more blocked type of weather.People on here prev are often seen to say ignore fi or anything beyond 7 days????Does this make longrange forecasts a waste of time or flexible!!!.Ive followed weather for fifty years so ive seen a lot of changes in the meto forecasts but barring a few execptions i cant remember many longrange forecasts hitting the mark.Not a dig at those guys given the complexity of the job ete just a thought looking at the current set up and meanderings

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1 hour ago, KasimWeatherQuarnford said:

Dec 2015:

archives-2015-12-15-12-0.png

Dec 16:

gfs-0-126.png?6

In my opinion we need to be careful here when comparing charts to previous years.

The setup of Low pressure moving across the Atlantic against a High pressure over/to East of UK is a relatively common occurrence year-round (to varying strengths and positions etc).

However, the whole Northern Hemispheric pattern I would class as substantially different. This year, we have heights "attacking" the polar regions and a vortex that is weaker, more fragmented and predominantly towards the Siberian side at times. We have had a quiet, blocked autumn overall.

Of course, for the UK, it would result in similar surface conditions at this point on the charts you have posted, but I do not feel it would necessarily follow the same pattern as last year. There are many other factors that can affect the outcome and these are constantly changing.

I await with interest as we approach mid-December, to see how it all looks to be panning out for the first winter month.

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31 minutes ago, warrenb said:

Meto must be confident as they are  tweeting their blog again, highlighting a cold start to winter.

I think there will be a rapid flip in the models soon.

Yes, seems a rather pointed retweet from them, followed by tips on how to keep warm. Suspect Meto remain quite bullish.

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7 minutes ago, Glacier Point said:

Theoretically, EC46 dayer should show continuity with previous, possibly shifting back a little on time scales if the MJO component is being modelled correctly.

EMON_phase_51m_full (2).jpg

It is showing some dawdling of the convective signal in the Indian Ocean and then eastward propagation. 

Thanks to you and tamara for your amazing input.  I did say in the last page that I believe the weekend of Xmas is when we could see the transition.  but it's just a guess at the moment.  what do you think gp?  it seems that all changes in weather happen around Xmas every time lol 

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35 minutes ago, johnny1972 said:

Frosty - the 06z is one run !!

I know it's one run, but it's not the only run showing a mild outlook which includes the Ecm ens mean & Gefs mean / extended..as I said, I treat each run on its merits and always try and give a fair balanced assessment on each run + some cold ramping when appropriate :D

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Not sure as to why people have taken mid December and pinned their hopes on the 15th , this was forecast so far out that it has to be taken as guidance , lets remember that is 14 days away , an eternity with regards models picking up on anything.  Patience people .

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The 4wk JMA update is following the UKMO script anyway. High slap bang over us week two and then signal for low mslp in the Med with positive heights over Greenland to see out the month.

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/model/map/1mE/map1/pztmap.php

Edited by Gael_Force
might have been confusing

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4 minutes ago, Gael_Force said:

The 4wk JMA update is following the UKMO script anyway. High slap bang over us week two and then signal for negative mslp in the Med with positive heights over Greenland to see out the month.

http://ds.data.jma.go.jp/gmd/tcc/tcc/products/model/map/1mE/map1/pztmap.php

Perfect, lets keep that vibe going...BIG EC46 tonight, if this sticks too its guns this place will stop with so much negativity I'm sure.

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