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Pattern The Great December Dump

Anyone got any thoughts on the mjo progression? Gfs is showing a stronger wave getting into p6 the euro just shrivels it away like my yard in July. I have my thoughts but wanted to hear someone else

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SD said:
Anyone got any thoughts on the mjo progression? Gfs is showing a stronger wave getting into p6 the euro just shrivels it away like my yard in July. I have my thoughts but wanted to hear someone else

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yeah I see that also... fairly confident the euro will end up the correct soulution
 
SD said:
Anyone got any thoughts on the mjo progression? Gfs is showing a stronger wave getting into p6 the euro just shrivels it away like my yard in July. I have my thoughts but wanted to hear someone else

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I have my thoughts but doesn’t mean much because I don’t know much. But GFS is always too fast and it’s crappy model too, and I am very concerned that the euro may be closest to being correct! Typing this as I bend over thinking about picking the towel up. Lol. Come mid January and the flip has not occurred and MJO not in 8,1,or 2 I’m picking that towel up fo sho!!!

For the record- I'm kidding about throwing the towel in!


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SD said:
Anyone got any thoughts on the mjo progression? Gfs is showing a stronger wave getting into p6 the euro just shrivels it away like my yard in July. I have my thoughts but wanted to hear someone else
Click to expand...

@Webberweather53 undoubtedly has his own thoughts about this. What I thought I recall him saying in the past is that the GEFS actually tends to do a little better than the EPS when the MJO is where it is now because the EPS tends to dampen the amplitude and move it too fast to the next phases. However, I also recall that the GEFS tends to have too high of an amplitude in phases 6-7. So, I’d educatedly guess it will be somewhere in between the two.

GEFS:
1576802357042.gif

EPS:
1576802455674.gif
 
GaWx said:
@Webberweather53 undoubtedly has his own thoughts about this. What I thought I recall him saying in the past is that the GEFS actually tends to do a little better than the EPS when the MJO is where it is now because the EPS tends to dampen the amplitude and move it too fast to the next phases. However, I also recall that the GEFS tends to have too high of an amplitude in phases 6-7. So, I’d educatedly guess it will be somewhere in between the two.

GEFS:
View attachment 28597

EPS:
View attachment 28598
Click to expand...
Its interesting Larry to me that the euro dont have the mjo in phase 6 at the minimum. You or anyone have any ideas?
 
BIG FROSTY said:
I have my thoughts but doesn’t mean much because I don’t know much. But GFS is always too fast and it’s crappy model too, and I am very concerned that the euro may be closest to being correct! Typing this as I bend over thinking about picking the towel up. Lol. Come mid January and the flip has occurred MJO in 8,1,or 2 I’m picking that towel up fo sho!!!

For the record- I'm kidding about throwing the towel in!


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8 or 2 helps us all; 1 isn't bad for y'all ... I hope if it happens your towel is wet beforehand and frozen solid afterwards ...

Screen Shot 2019-12-19 at 7.46.52 PM.png
 
accu35 said:
Some deep discussions on here today, 90% over my head.
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Allow me to sum up: The MJO is about to do it's typical thing, surprising everyone yet again by spending considerable time in phase 6. Therefore, join us across the street at Whamby Sads and Suds.
 
GaWx said:
@Webberweather53 undoubtedly has his own thoughts about this. What I thought I recall him saying in the past is that the GEFS actually tends to do a little better than the EPS when the MJO is where it is now because the EPS tends to dampen the amplitude and move it too fast to the next phases. However, I also recall that the GEFS tends to have too high of an amplitude in phases 6-7. So, I’d educatedly guess it will be somewhere in between the two.

GEFS:
View attachment 28597

EPS:
View attachment 28598
Click to expand...

Yes, the MJO forecasts from the GEFS when initialized in phase 5 perform better than the EPS although the GEFS is too fast & amplified.

ECMWF, JMA, & NCEP MJO Bias vectors Ichikawa and Inatsu (2017).png


Forecasts with 10 day lead time going into each phase for the ECMWF, JMA, & GFS (NCEP) models look like this:

The gray scale corresponds to root mean squared error with darker dots corresponding to forecasts with 10 days lead time going into that phase having larger error and vis versa (which is different from the above figure where the models are forecasting the MJO from a specific initial phase).


We can clearly see that the GFS model struggles immensely when the MJO is forecast to move into the Maritime Continent (presumably from the COD or the Indian Ocean), whereas the ECMWF struggles more than either the GFS or JMA models when the MJO is forecast to enter the Western Hemisphere (8-1).

ECMWF, JMA, & NCEP MJO Bias Forecast Ichikawa & Inatsu (2017).png


MJO predictability is typically on the order of 10-20 days & predictability limit which this paper defines as the model ensemble forecast spread multiplied by the square root of 2 becomes equal to the amplitude of the MJO. The MJO's predictability limit increases slightly when the MJO is being initialized with amplitude outside the COD and is also higher when its initialized over the Maritime Continent.

From Kim et al (2014):

MJO forecast skill in the CFS model increases when a strong MJO event is ongoing & its predictability increases by several days.

Screen Shot 2019-12-19 at 8.39.11 PM.png



The corresponding paper I'm referencing above wrt MJO bias vectors is this one:

https://www.mdpi.com/2073-4433/8/8/150
 
Wiki is not available (to me or to some others) ... probably has to do with the server issues a few days ago ... hopefully it'll resurrect soon ...
 
3 run trend of the EPS valid for New Year's Eve.

Keep a close eye on the strength & position of the ridge in the NE Pacific as we enter early January. Notice how the ridge is gaining latitude & becoming stronger in more recent runs of the EPS. This is something I've anticipated to happen (especially beyond this point in early January) based on the stereotypical, composite pattern response to West Pac tropical forcing, prior experience, & the understanding that individual wave breaks are typically dampened relative to reality at long leads in NWP models. Interested to see if this continues in later forecasts.

From this past Tue:
"I'd anticipate the 500mb pattern to grow more amplified on the models as verification approaches w/ the Alaskan ridge gaining latitude while the tropospheric polar vortex lobe over northern Canada slides southward in later outlooks."

https://southernwx.com/community/threads/the-great-december-dump.650/page-113#post-220236

Webp.net-gifmaker (8).gif
 
While the RMM index shows the MJO entering the west Pacific in early January, it's not that simple:

What we're really about to see are multiple fast moving convectively coupled kelvin waves projecting onto & interfering with low frequency variability associated w/ the +IOD & ENSO. This also means the downstream pattern over North America will differ considerably from the expected response during West Pacific MJO events.

Screen Shot 2019-12-20 at 5.17.18 AM.png
 
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