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December/January 2019/20 Winter Speculation Thread


AMZ8990
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6 minutes ago, Holston_River_Rambler said:

Sticking to giphy for now:

Looking good in the Eastern Indian Ocean: 

giphy.gif

Definitely a lot of talk on other sub-forums, this forum, and Twitter about the PV getting disrupted and maybe significantly.  Combine that with an an MJO that is weakening...model mayhem about to be at defcon 1 with one driver potentially being moved to the passenger seat and another taking over.  Going to see some looks that we like and some that we hate.  Buckle up, probably about to get some model whiplash!

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Just now, Carvers Gap said:

Definitely a lot of talk on other sub-forums, this forum, and Twitter about the PV getting disrupted and maybe significantly.  Combine that with an an MJO that is weakening...model mayhem about to be at defcon 1 with one driver potentially being moved to the passenger seat and another taking over.  Going to see some looks that we like and some that we hate.  Buckle up, probably about to get some model whiplash!

So, it is at least possible to see some of that cold in the PV make it south towards us?

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Does not seem like a boring pattern coming up.  Also, if the MJO sneak over into phases 1-3...that will likely result in a repeat(at least in part) of November.  Something to watch for and would be pretty cool.  EURO not buying that yet, but I do not thing modeling is anywhere near having this figured out.

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11 minutes ago, weathertree4u said:

So, it is at least possible to see some of that cold in the PV make it south towards us?

Forecasting a PV displacement/disruption is always a tricky proposition.  Odds are always higher for Asia since its landmass is so much larger.  Last year, the SSW actually screwed-up what should have been a good second half of winter.   PVs are a massive wrecking ball once unleashed.  Sometimes they are good and sometimes not.  Would be very unlikely any model has this ironed out.  I am not even sure of the timing right now.  Just been grazing on Twitter.  LOL and that can make one look foolish sometimes.  The one good thing is that a trough amplification is forecast for NA beginning about d9.  Theoretically, that would give a dislodged PV a place to settle into.   West or East...?  Your guess is as good as mine.  If high latitude blocking does develop, that means the gears at higher latitudes would just grind to a halt like a backed-up drain.  Things slow down and the jet up top kinks.   What I do like on the GEPS and EPS is the idea that NA would get hemmed in by ridging on both sides.  That might induce and omega block.  That has been a head fake all winter.  So really, right now the potential for a wild pattern is there.  We will just have to see where it goes.  We have noted on the forum for a couple of days that higher latitudes have a shake-up coming according to some model runs.   Thing to watch for is a lot of AN heights over the higher latitudes on either controls or ensembles.   

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Couple of 12z notes.  Euro looks good in terms of track for next weekend with marginal temps.  Who knew?  LOL.  Anyway, the 10d map is a class Arctic outbreak setup w/ soaring heights into EPO regions and over Greenland.  Nice look.  That look, while likely temporary, is exactly opposite of what we have seen most of this winter - thankfully!  Also, that is a major league storm setup then as well.  Lastly, the SPV is just getting shredded at 10, 30, and 50mbs.   

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Below is the 30 mb anomaly which is representative of 10 and 50 as well.  D1 it is perfectly wrapped up.  D10, it looks like a stretched rubber band.  This is why we are likely seeing so much blocking up top developing.  These are d10 maps.  Showing these not so much for details but so that I can provide an example of how the stratosphere looks at d10 and how the 500 levels of the atmosphere respond sometimes to disruptions above.  Blocking is showing up over NA at about the same time the SPV is getting hammered, and I mean hammered.

Figure 1 30mb anomoly

1242520427_ScreenShot2020-01-25at2_18_58PM.png.c8779ea65be9549af173475d2c5e233c.png

 

Figure 2  Euro OP at 500.  Note the blocking in EPO and Greenland regions.

1268202047_ScreenShot2020-01-25at2_21_43PM.png.e636c0e7e80b56c76b5d82029e6c8f25.png

 

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Just now, Holston_River_Rambler said:

What I'm hoping is nice about that particular prog. is that if the SPV is coupled, and pressure from heat fluxes and higher heights or whatever might have an easier time transferring down to the 500mb height than in some of the previous SSW/ splits

I think all of the high latitude AN heights that we have been seeing pop-up on model in now somewhat explainable.  Also, good luck to any model getting this right at the surface.  This is like turning a bull loose in a China shop!  LOL.

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Just now, Holston_River_Rambler said:

Not that I really trust everything that far out, but @Carvers Gap but it drops the trough in the west after that :( 

Yeah, the back side of the trough digs in.   As we have noted earlier, we probably aren't going to lock that trough in the East for long,  But if we can get it there just long enough, we might be able to steal a storm as it moves in and retrogrades back.  Most modeling has that.  If the SPV continues to be disrupted, this is going to be a wild ride.  Ensembles are likely not to have the LR pattern down at this point.  They might, but doubtful.  Why?  Because PV disruptions can lead to extreme solutions at mid-latitudes and those will get washed out on ensembles.

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Just now, Carvers Gap said:

As we have noted earlier, we probably aren't going to lock that trough in the East for long,  But if we can get it there just long enough, we might be able to steal a storm as it moves in and retrogrades back.

Yeah, I do like that the longwave pattern on the OP Euro at the end is continued by the EPS

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Here is the comparison.  The air mass that gets trapped by the two blocks is more substantial than 0z.  New run is on the left.  These are 850 temps.  Note how warm Greenland is.  This is a workable look as that trapped area of BN heights would likely pinwheel colder temps into most of the country.  Edit:  That is hour 348.

908179596_ScreenShot2020-01-25at2_47_21PM.png.6d7da346987099bf4a56eabf153857e8.png

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Looks like we are going towards one if those classic arctic air mass oozing southward against a possible SER. Where it ends up at this point is anyone’s guess. Tennessee can benefit from these scenarios. We actually could use some SER - not too much - to keep the air oozing rather than barrel through.

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What I see on the EPS is a model that deepened the trough over the East but has some solutions over the West.  And yeah, if you see a trough leaning like that....storms will ride the boundary.  Just have to catch one that hits it at the right time.  I will go back and look at the individual 500mb members.  I suspect there will be two camps, eastern trough vs western trough.  Split the difference into the Plains and that still works.

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Yep, so IMO what is skewing the 500 map late(my maps at wxbell don't look quite as drastic w troughing into the West) is a cluster a individuals(roughly 1/3) w/ AN heights in the East.  Those numbers are fewer, but very strong.  So, really what looks like a trough going into the West is the model stuck between two solutions but leaning towards an eastern trough.  As we get closer, the ensemble will eliminated the members which are likely not going to happen.  That will sharpen where that trough goes.  So, I might actually guess the trough will drop into the center of the country.  Almost all ensembles are having the same issue.  What we are getting is solution that splits the difference.   What is encouraging is it is possible that the block actually captured part of the PV on the EPS and locked it over NA.  Would be nice if future runs did the same.  Again, until this SPV disruption gets ironed-out...going to be some wild runs.

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