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December/January 2019/20 Winter Speculation Thread


AMZ8990
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With a ridge at 500 in that nation's mid-section at 300, there is a southern winter storm to our west.  Message from the GFS, if we get a system that cuts to the Lakes with the incredible cold in Canada...it may well work under the ridge at 500.  Going to be very important to look at surface temps in combination with 500 patterns.

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31 minutes ago, Carvers Gap said:

Just for fun and not for verification purposes, take a look at the 0z GFS at 312.  Look at the 500 anomaly, and then look a the surface weather under it.  Pretty incredible.   

That means the cold is shallow under the ridge. Sure enough you, if you look at the skew-t at 312 the surface is approximately the same temperature as the 500mb level of the column.  Look at 120 by comparison,  500mb is 20+ Celsius colder than the surface.  Usually higher heights means warmer but sometimes with the shallow, dense cold slips under the higher heights and gives cold surface temps. I just really hope it's right but the vortex in the Pac NW remains ugly. 

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On 1/4/2020 at 12:26 AM, John1122 said:

00z GFS has no Scandinavian ridge.  Transient cold shots, mostly potential record highs. Hopefully we can get out of the ditch in the next two weeks.  If not, it's probably time to completely re-evaluate winter in this part of the world and assume we now have the climate of Central Gulf coast states 20 years ago.  Doesn't mean we can get cold or snow any more, just means it will not be a given that we will get snow in winter. 

“it's probably time to completely re-evaluate winter in this part of the world and assume we now have the climate of Central Gulf coast states 20 years ago.”

Well said! Could not agree with this more. Hard to deny the changes that are happening, we all see them in our region (and many other regions as well for that matter).especially in winter.  Climate variability, GW, just subtle changes, or maybe just an “off” climate cycle of 30 or 40 years then a switch up, who knows.  But, it can not be denied, at least in the relatively, extremely short period of Earth’s history/evolution/record keeping  period we call 20-30 years or maybe longer, that our regions weather has changed and will continue to do so. Unfortunately for most of us that deprives us of one of our great joys of life! Oh well, it is only a matter of time and patience until we see real snow again. I think.

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Happy New Year everyone. Im a little confused on the OLR and what that means. Maybe jax or Carver can help with that. I guess it is kinda in relation to the mjo. Unfortunately we are entering the maritime continent, which are warm phases. Is there really anyway  to tell where we may go after mid month at these long leads? Just curious. 

I would like to see the mjo in other phases other than the maritime continent all winter. Just my two cents 

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...And sure enough, the GFS waa aay out there shows that as a possibility.  The Euro seasonal was released this morning - I think(didn't look yesterday).  Looks good for February.  JB has some information on it....but in general the trough is reforms in the East.  That fits nicely with a Scandinavian Ridge which we have talked about for a few ays and D'Aleo adds some nice commentary today about it.  Bottom line, there are some real and tangible signs now that the NA pattern is about to shake-up.  I can see a scenario where the pattern relaxes and the trough reforms out West.  I can also see a pattern where the MJO is no longer a driver and the trough reforms in the East.  It may very well be a replication of the Fall pattern which was record warmth to seasonal to very cold..  Final note:  The 12z GFS does have a full latitude ridge which I think would revert to a western ridge and eastern rough.  It appears to be a retrograding ridge(loose definition) and that also fits nicely with the Scandinavian ridge that HM has spoken about for a few days.  The last snapshot would likely put the ridge out West, but also open for debate.

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If you want to see a pattern flip...need to really pull for the 12z GFS as it is a retrograding pattern probably induced by the Scandinavian Ridge which basically forces the entire thing to reverse.   Let's see if it has any model support.  I think PSU noted in the MA forum that many of our best winter patterns are a result of a retrograding pattern vs one that just rolls forward.  It is not quite there at the end of its run but watch the features over the Western Hemisphere.  The eastern Pac ridge pulls north westward.  A trough dives westward into the GOA.  The ridge over NA is beginning to reform in the West.  That look is supported by Euro seasonal models and the CFSv2 at times.  I think one of the Weeklies runs had a similar look.  Not sure the MJO supports any of that yet...Someone reming me, does the MJO lose its affect as winter progresses?

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The trends of the last 24 hours have all gotten better with that potential system Tuesday with that 3k NAM topping the stack with 2-4 inchs all the way from just East of Clarksville to SW VA. The GFS is confined more to the east but it's snow shield has expanded westward as well.  The RAP/RGEM have SE Kentucky in the bullseye. Hopefully todays trends that have put more of us in the potential game continue into future runs.

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6 minutes ago, Carvers Gap said:

That is a complete and total pattern reversal on the 18z GFS...We have been there before regarding false flips and this is just outside of d10.  We all know the drill.  But folks, that was a complete and total pattern reversal on that run.

I am down for anything except more rain lol!

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0z NAM suite is showing snow more in Kentucky but if you look at the soundings the 850s are well below freezing and the precip type on the soundings say snow even in places like Union/Grainger Co where the model is showing rain. Which I believe it is showing because surface temps are mid 30s. So any decent rates will likely fall as snow instead of rain if the NAM is to be believed. 

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SEKy, and SWVa look pretty decent for a nice, quick hitter on virtually all modeling. The Euro joins the models that are showing rain on the maps for parts of northern Tennessee but skew-ts show snow soundings. Almost all the models showing the system have 850s at freezing or well below, 925s (2400ft) at freezing or maybe 33, and surface temps in the mid 30s. They all say best guess precip type as snow as well. 

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If there is one thing that is encouraging about the MJO depiction on the Euro...it is faster than its EMON in exiting the warm phases.  EMON had the MJO in warm phases for a more than 20 days.  I think the Euro is now down to about 14 before entering into the COD.  Question at that point is where does it go then?  The 0z EPS was much quicker removing the eastern trough than any other ensemble this morning and matches its MJO look.  No idea if it is a relaxation of the current pattern or an actual change.  I will be interested to see if the Euro Weeklies actually support the Seasonal depiction.  This will be the first time in quite some time that the Weeklies will be derived from a trough that has been dislodged from the West.  I do think a pretty big shake-up to the pattern is coming.  The GFS yesterday was likely too quick.  Would like to see the EPS continue to push the trough out at 12z.  Don't want it stalled in time.  We know how that usually turns out if so.

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