December/January 2019/20 Winter Speculation Thread

[Carvers Gap]

2 minutes ago, Wurbus said:

The difference in temps on the Canadian and GFS in southwest Canada at 240 is pretty remarkable. GFS has southwest Canada between -25 to -40 degrees, while the CMC is 15-20 degrees. Almost a 50-60 degree difference!

You catching the Euro run here at 12z?  Interesting to 174 for sure.

[Wurbus]

4 minutes ago, Carvers Gap said:

You catching the Euro run here at 12z?  Interesting to 174 for sure.

Yeah. Euro and GFS look pretty close so far. Both have cold temps in Canada and the piece of energy in the midwest and northwest at 198. The piece of energy in the northwest looks a little stronger so far on the GFS.

[Carvers Gap]

GFS is colder.  The though has crossed my mind that if the ridge in the Pacific continues to be crazy strong...it might just dump a significant amount of cold air into NA and that would trump everything else.  Euro is a hair eastward with the trough...  

[Carvers Gap]

I said I would refrain from talking about the Weeklies in depth unless they changed... @Holston_River_Rambler  , are you able to build both an 850 and 500 loop of that run?  Pretty big changes early in week 4.  Looked like the GFS but about a week later.  SER continues to fight, but the death ridge is absent after week 3.

[Carvers Gap]

Basically, it is a pattern where cold drops into the front range and comes eastward in pulses.  Now, the Weeklies are sorely guilty of continuing the derived run in perpetuity, so there is that.  However, maybe we are starting to see some cracks in the current pattern.  Now, if we go with the 6 week pattern cycle rule...Warmth began here around Dec 8th.  Add 42 days to that and you get January 19th.  The current return to seasonal(important note...not BN but seasonal and also along the battle zone for temps) occurs on that model around Jan22-23.

[Carvers Gap]

Interestingly, the Euro Weeklies Control depicts a similar NA 500 pattern to the last four runs of the GFS.  We were kicking around the realistic nature of that run.  Looks like another model(albeit control) has a similar look.  I suspect this is about the time that the MJO goes COD.

[Holston_River_Rambler]

@Carvers Gap

Here are the 500 mb of the weeklies:

1/2:

12/30:

and the 850 temp anoms. 

1/2:

12/30:

 

 

 

 

 

[Carvers Gap]

15 minutes ago, Holston_River_Rambler said:

@Carvers Gap

Here are the 500 mb of the weeklies:

and the 850 temp anoms. 

 

Awesome.  Would it be too much to ask to have the 12.30 gif in the same post for comparison.  If not...I am super appreciative of the one you posted!  If you can just edit the post and put the old run first...

[Holston_River_Rambler]

No worries, I can. I keep trying to find the run to run delta panels that Bob Chill has been showing in the MA for the EPS, here is the most recent example:

 

I think it's like the GEFS 48 hour forecast trend setting on Tropical Tidbits, but for the Euro. I think only Weatherbell has it since I can't find it on weathermodels. 

Actually, I see what you mean now. I will go back and edit the first post. 

 

 

[Holston_River_Rambler]

Somehow the 500 mbs were in sync for easy comparison, but not the 850s. 

I didn't do that on purpose, it seems to be just luck of the draw. 

[Carvers Gap]

Thanks, Holston.  Yeah, the trends on the Euro model suite have been good.  

 

Overall obs...I have said it for three days...just was super weird to see ensembles almost stop the hemispheric circulation pattern around the 10th.  Now, we are seeing more volatility.  I seriously doubt the models are not done trending.   What I do think we need to really root for is the incredible cold model runs to verify AND for the Pacific Ridge to push cold air into the front slopes of the Rockies.  While it is not ideal.  We can deal with extreme cold being sent into MT and then have it modify as it comes eastward.  Now, It will be hauling tail, but we at least "should" see some cold attacking the eastern ridge and reducing it to a potent and pesky SER.  That is where modeling seems to be taking us over the past few days.  Jan10-20 still looks like a very warm time frame, but if we can score a strong cold front in the middle of that...that would make things a bit more tolerable.  While I don't see a pattern flip of any kind...more of a pattern modification.  It is almost like that big Pacific ridge just pumps so much cold into the West, it has nowhere else to go but east.   It is possible that if we get that much cold into the pattern that the sheer volume of the cold air becomes the driver and not the MJO.  That big Pacific ridge is going to act like a giant pump and send cold air into the West...and then hopefully it spreads out. Models still look like they are adjusting to that.  I wouldn't be surprised to see the worst of the cold drop into the Plains when it is all said and done.  Anyway, don't want to belabor things to much...but weak Nino climatology supports the switch.  And yes, sound EXACTLY like the conversation last year minus the SSW.  I acknowledge that for those that say, "Here we go again."  Cause yes, here we go again.  LOL.

 

Lastly, I read some D'Aleo stuff today.  He was talking about how the ENSO signal is basically a neutral but weakly positive.  It may well be that this winter is never classified as a weak El Nino.  It may be a Nada, and Nadas are not great winter drivers here.  We either need a weak El Nino or weak La Nina - not too much and not too little. It may be that the El Nino is not quite strong enough.  Just a though.  Probably more likely that the MJO region is giving us the shaft once again.  LOL.

 

[Carvers Gap]

So, the 18z GFS and ICON both show a mixed bag next Tuesday into Wednesday now.  

[Carvers Gap]

Been several good runs of the GFS...the 18z will not be.  The PV over Greenland doesn't move and cause some weird little vortices to spin around it.  The BN heights at 500, instead of cutting across NA, goes to Seattle, heads due south, and re-emerges back in the Pacific around San Diego and dies.  Weird run...but again, the PV over Greenland weakens on most of these good runs.  NA is much warmer on this run as well,

[Carvers Gap]

At 380, the GFS has a system heading southwest after making landfall in BC.  Trough is right under the ridge.  Really doubt that happens.  Pretty wild run though in regards to that!  @weathertree4u that is probably something I would say is not realistic.

[John1122]

That was one of the worst/warmest runs I've seen of any model.  Keep in mind the GFS has a cold bias and has been verifying about 6 or 7 degrees too cool, even still no one in the forum gets below freezing from Jan 10th-19th. We may have wide spread mid-winter 70s though. 

[weathertree4u]

2 hours ago, John1122 said:

That was one of the worst/warmest runs I've seen of any model.  Keep in mind the GFS has a cold bias and has been verifying about 6 or 7 degrees too cool, even still no one in the forum gets below freezing from Jan 10th-19th. We may have wide spread mid-winter 70s though. 

Go big or go home! 

 

[Carvers Gap]

Band is back home safely.  Vols pulled one out.  And wx modeling is warm.  Two out of three aren't bad!

[Carvers Gap]

And if one was wanting to cherry pick something positive from the ball of red over the SE...there is some hint on the 12z GEFS of AN heights over Greenland - been trending that way for a few runs.  I honestly don't think the GEFS looks worse.  The operational is obviously worse, but the GEFS has Alaska and Greenland warming late in the run.  Eventually that would for a fairly substantial block if real.  Something to keep an eye on.  Seriously TN fans...that game was nuts last night.  Can't remember the last time I have seen us pull one out with a successful onside kick recovery.  All hope looked like it was lost...sort of like our weather pattern.  Not sure what the wx equivalent of an onside kick is, but probably time to start prepping that.

[PowellVolz]

14-15 had some decent snows in NE TN in February.  Most snow I can remember in February in my lifetime in Kingsport.

I believe it was Feb 14/15’ when we had a predicted front end thump to rain in the valley and it never changed to rain north of 40. Had some sleet mixed in but ended up with 8” at my house. I remember it was low 40’s and rain at Ober Gatlinburg, upper 20’s and heavy snow at my house. I seem to remember the theory was the SE winds created a CAD up against the plateau that was strong enough to hold back WAA.


.

[Carvers Gap]

And the 18z GFS has rediscovered the cold in d10-15.  Some notable model trends today for those hoping winter arrives.

The Good...

1.  Big Scandinavian Ridge showing up in the LR of some operational and ensembles.  That often leads to perturbed PVs and is a definite precursor to blocking.

2.  Some model tendencies to push the ridge out of the East.

The Bad...

1.  One version of the Euro is hinting that the MJO may cycle back in 4-6 after it leaves around Jan 20.  Another seems to take it towards better phases.  In general, the worst version has verified so far this winter. 

2.   In about 6 weeks, it begins to get quite difficult to snow in the valleys minus an oddball storm.  We are about to lose three of those weeks.  So the window(good or bad), is going to be Jan 20-Feb14.  That is about our best shot.  I don't see anything that depicts sustained cold.  What we might hope for is a storm pattern with cold sometimes in the mix.  Welcome to Nino patterns and why I don't like them.

[John1122]

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. 

[weathertree4u]

42 minutes ago, 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. 

Yep, been singing that tune since mid December!

[weathertree4u]

4 hours ago, 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. 

In reality, I know where I am, North of Nashville, it really only takes one or two big snows to make it a memorable winter, we may yet pull something out before it is over - I am honestly more concerned about the rainfall potential over the next 10 - 14 days.

[Holston_River_Rambler]

Courage friends. As soon as the GFS sees the MJO somewhere else, even if only the COD, it will show fantasy storms again. 

Ugly for rain, for now though. GEFS and EPS as they evolve in 10 - 15 days range try to aim the jet from the SW to NY state and that puts us on the right entrance region of it. 

EPS mean is 5.8 for Crossville and the control drops nearly 10 inches of rain. Juts gonna depend on where the best lift sets up for each system, in terms of flooding, but I think the heavy rain is a done deal. 

In the mean time, looks like we will get a good upper low pass, from the plateau eastward:

Although the energy is getting a little squished. Hopefully we can get a snow squall or two this PM. Winds have already picked up here on the plateau and the temp is falling. 

[Holston_River_Rambler]

Found this on Southwernwx this AM. 

Eric Webb shared a link to Paul Roundy's experimental MJO forecast model and this also shows not only tropical forcing, but also how it impacts the N. Hemisphere's 500 mb pattern. 

It shows a possible end to all this by the end of January and even if it still takes a bit to develop a good pattern after that, at least it should shut off the rain for a while. 

 

[weathertree4u]

13 minutes ago, Holston_River_Rambler said:

Courage friends. As soon as the GFS sees the MJO somewhere else, even if only the COD, it will show fantasy storms again. 

Ugly for rain, for now though. GEFS and EPS as they evolve in 10 - 15 days range try to aim the jet from the SW to NY state and that puts us on the right entrance region of it. 

EPS mean is 5.8 for Crossville and the control drops nearly 10 inches of rain. Juts gonna depend on where the best lift sets up for each system, in terms of flooding, but I think the heavy rain is a done deal. 

In the mean time, looks like we will get a good upper low pass, from the plateau eastward:

Although the energy is getting a little squished. Hopefully we can get a snow squall or two this PM. Winds have already picked up here on the plateau and the temp is falling. 

For sure, not liking the look for heavy rain in the Middle TN area, heck, for that matter, essentially region wide.

[weathertree4u]

Just now, Holston_River_Rambler said:

Found this on Southwernwx this AM. 

Eric Webb shared a link to Paul Roundy's experimental MJO forecast model and this also shows not only tropical forcing, but also how it impacts the N. Hemisphere's 500 mb pattern. 

It shows a possible end to all this by the end of January and even if it still takes a bit to develop a good pattern after that, at least it should shut off the rain for a while. 

 

Thank goodness, hopefully we can avoid real issues with flooding by the end of the month but it will be close. 

[Carvers Gap]

QBO has fallen to 1.66 from 5.07.  That is a significant and slightly accelerated drop compared to the past few months.  What that means is that the QBO, at least for now, is not stalled but still dropping at a good clip.  Should be negative sometime later this month if that continues.  Again, the QBO behaves differently with solar min and max phases.  Actually the best QBO state for us is a positive QBO with a solar max.  The negative QBO with a solar min does include a slight SER(the good SER and not the massive deal that we are about to have).  The good think about a -QBO is that it can enhance blocking and force strat warming in polar regions once established as negative.  Again, I have lived through these types of winters before - many of them.  The 90s had some truly snowless winters both in Knoxville and in Kingsport.  So, this is nothing new for me and why I am always less excited about these types of winters.  As for LR modeling, there is some movement of the ridge in the LR...but nothing significant yet.  The MJO might be trying to show some signs of working around into more favorable phases on the Euro...but still a ways out on that.  The EMON was certainly not encouraging yesterday, but it does not come out every day like the Euro.  It may very well be that this is not a true weak El Nino, even though slightly positive.  It certainly has some Nino characteristics with rain though!  However, Nada patterns are not great IMBY.  In fact they are usually pretty lousy in terms of winter.  It may very well be that the Nino pattern is not strong enough.  Too strong is not good.  Too weak is not good.  A regular or weak(not near neutral) El Nino will work as well.  Even a weak La Nina will work - dry but cold with extremes.  If I ranked in order the winters we don't want to have...Super El Nino,  moderate/super La Nina, and nada.  IMHO, a case could be made that during the last couple of winters that we have had pretty much nada stuff (conflicting Nina and Nino signals).  Maybe it was JB or someone in the MA said that the Pacific basin might need a shake-up with an actual basin wide Nino or Nina event(not the super stuff...just normal Nino or Nada).  That current colder water near SA is trouble as it favors a SER.  It is more of a problem than folks give it credit for.   But I can't really complain.  I saw a foot IMBY Dec 2018, extreme cold  for a week in the winter prior to that, and snow twice already this winter.  And winter at this latitude has not disappeared.  It is just out West, and I can pretty much guarantee that at some point winters that pattern will switch east.  And I say it periodically, the flipping of the AMO during the late 80s coincides with this time frame of crap winters.  There are other drivers at work for sure...but the AMO is a proven cold weather driver for this forum area, and it has been opposite of where we need it for about thirty years of a forty year cycle.   But alas, this winter is not over.   If we loop back into 4-6, maybe so.  I don't have a ton of hope for sustained winter wx, but we might work our way into a 1-2 week tracking time frame.  

[Carvers Gap]

Meanwhile, there are winter wx advisories up for the eastern mountains.

[Carvers Gap]

Some tangible improvement on modeling today.  Not going to mention all of it as it might revert and then my typing is just a waste of figurative breath.  Thing to watch is when/if the trough lifts out OR rolls forward.  Hint:  Keep pulling for that Scandinavian ridge to be the real deal on the EPS.