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December 2021 Obs/Disco...Dreaming of a White-Weenie Xmas


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1 minute ago, SnoSki14 said:

Pretty high amplitude MJO mid December onward. Does look like it's going to 8 but we've seen these head fakes before. 

Wonder if we'll start seeing changing on the modeling soon 

I think in both 18-19 and 19-20 it showed that a bunch and then would ultimately loop right back to 5-6 again

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50 minutes ago, CoastalWx said:

Even getting eastern Greenland ridging too but that dam SE ridge is stubborn. Maybe we get some cold to ooze in?

Yeah if we assume the model is handling the polar domains fairly well, I'm figuring we end up decently colder than it shows at least up in the northern latitudes. It's really hard to have a ridge in AK and some ridging in greenland and end up torching....I'm not even sure how that happens at all outside of a temporary cutter or something.

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1 hour ago, SnoSki14 said:

Pretty high amplitude MJO mid December onward. Does look like it's going to 8 but we've seen these head fakes before. 

Wonder if we'll start seeing changing on the modeling soon 

Questions remain as to whether the wave momentum and related latent heat fluxing/forcing in the dispersion model will remain south of the Equatorial band, however.

Through last week, the publications by CPC had an ongoig mantra implying that forcing would be primarily 'south based'

Primer blah blah:  The problem with that ( for the N. Hemisphere ) is that the Equatorial band represents a kind of 'wall' in free space - like an atmospheric asymptote in some sense... Which by constraint, there is limited mass exchange across that virtual boundary.  Such that a wave propagating ( primarily ...) south of the Equator, does not force upon the N. Hemispheric eddy. The Hadley Cell is split along the Equator, with the rising motion moving away at higher elevations ( I had posted an illustration of this a few pages ago....). 

The caveat on that is if the wave laterally grows in the N-S coordinate, which can happen and through that 'wall' - wave mechanics are different than Coriolis driven circulation systems.  Anyway, should the wave its self begin manifesting propagation over the N side, then we start dumping LH and we're on...

Another concern... the La Nina foot-print is in destructive interference with MJO waves phase 7 around the horn to 2's.  ..etc.   That means that usually ( but not always) the total Hemispheric eddy would offsetting these MJO's leaving the Marine continent - suppression. 

The new weekly PDF publication:  they have opted not to mention the southern propagation bias - I don't know if that implicitly means that wave 'has grown N' or not.  Since they are mentioning the west Pacific TC activity - that would tend to suggest it does.   So, ... hm, we'll see.  But if recurving TCs enter the discussion, that definitly changes the map on whether LH flux gets involved with the WPO ejection routes across NP.  ... I mean, that's like a full-on vaccine syringe injection of plaguing shit circulation cure right there - maybe.   But that's a maybe that is not merely hope - but something to look for.

I also find it interesting that the extended GEF members are hinting at some Siberia- Alaska regional height rises.  I have noted ( personally ..) in the past, that sometimes these regions will begin to manifest rising heights ( lowering EPO phase ) prior to the advent of the W. Pac cyclone(s)...  It's always sort of made me wonder which is really the chicken vs egg in the pattern change.... This is wandering into a way too long didn't read territory for iPhone swipers but ... that seems to suggest the TC capturing adds/positive re-enforcemet to pattern change that is already in place, if too nuanced to see right away.  Interesting....

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I'm looking forward to it my self. But, not just for the deliciously sensible appeal out of doors ...etc. We used to have a surprisingly reliable adage back in my collegiate weather lab dweeb days ...

" First it gets warm, then it gets cold: Boom!"  ... not always.. I mean, it didn't work out too well in 2006 - it stayed annoying for a month and then took another 10 days to agonizingly break colder.  Finally got a storm - I think Valentines...

In the interim ...yup, big warm anomalies in route for much of the CONUS.  I would surmise greatest confidence [ for personal assault on Holiday season dignity] will be S of the 40th parallel... basically Iowa to NYC. 

How 'big' those anomalies register here depends on S-SE Canadian wave train.   There are some indications among individual operational versions and ens, that an episode or two of confluence may send north and/or b-door bouncers in front of our entrance into the warm party like the rope handler outside the door of Studio 54.  

If those don't interfere ... that present EPS/ GEFs blend does hearken somewhat back to 2006 and 1999 in my mind. In both Decembers of lore were also examples of unabated S-SE ridge expansion, transporting unusual 850 mb above climo.  Both those years I recall a 70F afternoon or two during -

 

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3 minutes ago, Sugarloaf1989 said:

If we do get snow before Christmas,  I just hope grinch torch doesn't show up on Christmas Eve. Last year was terrible,  snowcover vanished overnight. 

Last year's grinch storm was an all timer. Prob 95% of grinch storms couldn't melt off 10"+ of pack in 8 hours like that one did....we had grinch storms in 2007 and 2008 which both failed to melt the pack. Last year's was like the Arnold Schwarzenegger of grinch storms.

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Just a quick note for some of you guys bummed over the mild December. Many have noted that this la nina has continued to shifted eastward, at least as much, if not maybe a bit more so than I had expected.

Consider this excerpt from my write up last month regarding how the month of December can evolve differently based upon ENSO type.

There exist some notable differences between these two disparate types of la nina events. Here are a couple of schematics outlining these differences:
Differences between east-based La Nina's & central-based La Nina's 
Figure A is east-based. Figure B is central-based
One.gif
DJF 500mb for East-based years:
New%2BEast.png
 
 
DJF Temps

New%2BEast%2B1.png
 
Ironically in east-based years JFM is colder than Dec. Dec is typically the warmest month in the
 east-based years, which runs counter to typical cold ENSO climo.

JFM 500mb east-based years
JM%2BEast.png
 
 
 
JFM Temps
 
 
New%2BEast%2B2.png
 
 

 
 
Compare all of that to central-based La Nina years:

DJF 500mb

 
DF%2BH5.png
 
 
 
DJF Temps
 
DF%2BModoki.png
 
 
December is the coldest month for central-based Nina's. 
One thing worth noting is not all East-based Nina's are frigid, as there is variability due to the relatively weak
 ocean-atmosphere coupling. This is because many east-based events, as is the case with modoki el nino events, are 
weaker. You can have warmth, especially if the event is weaker, and one such case is 2005-2006.
 
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