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[Global] Teleconnections: A Technical Discussion

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1 minute ago, Nchaboy said:

Do we want it in the cod? Just seems to be stuck in 5 right?

No and it’s not stuck in 5 

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3 minutes ago, Allsnow said:

No and it’s not stuck in 5 

Ok. So the red line is the active line on that plot?

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1 minute ago, Nchaboy said:

Ok. So the red line is the active line on that plot?

No. But the rmm plots like to chase convection. So it can skew the actually placement. If you look at the vp200 maps this is in p6 already. 

 

Look back a few pages in the obs thread. A few of us discussed all of this. 

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20 minutes ago, Allsnow said:

No. But the rmm plots like to chase convection. So it can skew the actually placement. If you look at the vp200 maps this is in p6 already. 

 

Look back a few pages in the obs thread. A few of us discussed all of this. 

Hasn't Don been posting that it is still in 5?  

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7 minutes ago, Frankdp23 said:

Hasn't Don been posting that it is still in 5?  

Yes he has 

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8 minutes ago, Frankdp23 said:

Hasn't Don been posting that it is still in 5?  

The Vp maps I’m using have it in 6 currently. I’m not sure what method @donsutherland1is using. Again don’t take those rmm plots as gospel. Remember too, the eps looking horrible at day 15 is a direct response of it mjo forecast. 

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4 minutes ago, Allsnow said:

The Vp maps I’m using have it in 6 currently. I’m not sure what method @donsutherland1is using. Again don’t take those rmm plots as gospel. Remember too, the eps looking horrible at day 15 is a direct response of it mjo forecast. 

 

Yes, it's in 6. Should be 7-8 w/in a week.

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2 minutes ago, Isotherm said:

The momentum response which many of us have been forecasting/discussing for weeks is occurring -- strong FT surge, EAMT rising rapidly, and AAM tendency, rising sharply. This coinciding w/ MJO propagation through dateline. The much advertised tropospheric alterations in progress.

 

@Tamara @Snowy Hibbo @Bring Back 1962-63 @Blessed Weather @Singularity

 

 

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So in other words the model depictions will soon change due to this?

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1 hour ago, dmillz25 said:

So in other words the model depictions will soon change due to this?

Yes. It’s already beginning to some extent. A week from now, we will be tracking. 

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Just now, 33andrain said:

Yes. It’s already beginning to some extent. A week from now, we will be tracking. 

Excellent (Mr. Burns Voice)

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4 hours ago, Tamara said:

 

The general premise of pre-Christmas thinking is/was not wrong in its logical assembly of GSDM diagnostics at the time, but is almost certainly proving too progressive in nature

 

With added westerlies now properly switching frictional torque tendency from the tropics, and in the knowledge that frictional torque leads the tendency of mountain torque - we have to take into account propagation times for these processes, with full extra tropical impacts occurring up to 10 to 12 days later.  But due to the amount of inherent "westerliness" already present in the atmosphere there is already a next phase of poleward +ve momentum process taking place and recent jet retraction (responsible for stronger sub tropical ridging) is starting in process of reversing.

 

Its necessary to factor in the developmental times and associated uncertainties related to stratospheric diminution continuing to slowly unfold. The nature of both the speed and amplitude/eastward progression of tropical convective forcing which is driving future potential tropospheric amplification, and the timing of potential downwelling of -ve zonal wind anomalies have been/are part of the moveable feast I was speaking of earlier.

 

This prospect has not gone away, but we must continue to be mindful of realistic timetables. With this in mind, I tend to agree with @PB GFI on the obs thread that Jan mid month looks to be the earliest time to see the models  really switching the decks of the NAM. There are provisos, in my opinion, to this (still likely) scenario - its important that the tropics do not throw any de-amplitude curveballs with convection passage through the Pacific and create conditions for AAM tendency to stall and be reflected in turn within the extra tropics through a lower and less progressive extra tropical GWO orbit

 

Mid month expectations of real change rather reflects the principle of prognosis of winter 2012 to 2013, if not obviously necessarily precise identical implications for blocking at face value this time around.

 

This December we have some -ve forcing disconnect in terms of the sub tropical mid latitude ridges. I think, by the way, that @donsutherland1posts on another thread about the +ve SOI disconnect and future observations as to how January may play out are highly interesting and played some part in how my mindset has evolved in recent days - and how this particular post has helped come about.

 

With relative angular momentum significantly higher than the same time compared to Dec 12 - the pattern is still inherently more "pre-amplified" (if you will) here in Dec 18, so it provides me with more interest, still, to the way ahead here.

 

 

 

Really good and interesting post Tamara - enjoyed it very much. I've cut and pasted some bits by way of some follow up discussion - I'd value your thoughts...

 

1. Timing. Agree 100% that timing has been an issue this season so far - with signals in place and being pushed back. And not for the first time to be honest - in previous years we have seen timings pushed back and processes slowed. The only exception I can think of immediately would be the very swift end to the "Beast" of March this year where extraordinary processes led to such a swift retrogression of the block that warm air undercut our late winter UK cold much faster than anyone, including the Met, predicted. Ignoring that example as an example of really unusual conditions is there any thought as to why timescales tend to run longer than expected, and why NWP is often too progressive with signal reading? Is this just a bias we need to absorb, or are there physical processes within GSDM modelling that arise frequently to jam the spanner into the wheel? I'm happy to accept bias if that is all it is....but wondered if you have any insight into the physical processes going on.

 

2. Paras 2 and 6. I also see a disconnect in terms of sub tropical mid latitude ridges - but am also very aware of higher than expected GLAAM readings for the season as a whole so far - and have posted about this before. Given what you neatly describe as a "pre-amplified pattern" what is your reading of the impact of this pre-amplification....and do you think it has any impact on the apparent mid lat disconnect we are seeing? Has pre loading of the atmospheric AAM served to boost the Hadley Cell by impacting significantly just north of 30N? I cant quite conceptualise the overall impact of this pre amplification - and being a visual learner of less than average scientific knowledge but quite sharp visual/conceptual understanding I need to get a handle on a process before I can interpret it! 

 

3. NOAA have posted that the MJO slowed down as it interacted with rossby wave activity - relates to para 3. I'm struggling here. I thought that MJO activity initiated much of rossby activity in the first place....but their pdf post recently suggests they are mutually exclusive and this activity has interfered with the forecast. From where does rossby activity originate if not from MJO passage - and why would it slow progress down? Just more model bias??

 

4. Parallels with 2013 are really interesting. Funnily enough I was just running this site linked to me by Singularity that shows the 2013 split...and thinking that it looks much like the one we have coming. Very similar around Jan 9  http://birner.atmos.colostate.edu/SSW-animations/anim-PV/2012-2013_530K/loop.html - and the same wQBO label too for that year. Sebastiaan over on Netweather has noted that the majority of split vortex events in wQBO years tend not to downwell. In 2013, however, we got the downwell. Or....was it actually more of a tropospheric "sandwich" - with upwelling impacts caused by the 5 - 8 GWO orbit impacting on the trop which was simultaneously being harangued from above...and ultimately is the success of any downwelling SSW all about timing between strat and pacific?

 

Which puts us back, once again to timing. My current bugbear. My own thoughts for this season have panned out not too bad - but timing is a problem. I notice you also referenced my little pet issue of "seasonal wavelengths" - a topic I've asked several people about on more than one occasion and never had a concise and punchy answer as to what these wavelength transitions/processes are and why. If you have guidance there I'd be glad of it.

 

Keep up the great work - very thought provoking.

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