December/January 2019/20 Winter Speculation Thread

[Mr. Kevin]

Just now, Carvers Gap said:

I think I had to unfollow Hugo because he was posting so much.  LOL.  Either that or my mind filters him out.  Been several folks posting about it today on multiple platforms.  

Who were they Carver so i can take a look? 

[Carvers Gap]

18 minutes ago, Mr. Kevin said:

Who were they Carver so i can take a look? 

I would just grab some 10/30/50 mb maps and take a look.

[jaxjagman]

Wave 2 sure looks better than yesterday,in the long rabge

[Mr. Kevin]

1 minute ago, jaxjagman said:

Wave 2 sure looks better than yesterday,in the long rabge

2 minutes ago, jaxjagman said:

Wave 2 sure looks better than yesterday,in the long rabge

 

Jax, do you think this has anything to do with qbo reversal to negative or is it totally different?

[Mr. Kevin]

6 minutes ago, Carvers Gap said:

I would just grab some 10/30/50 mb maps and take a look.

I just wanted to know because i would add them to my Twitter followers. Matt hugo is the only one ive noticed that mentioned it.

[AMZ8990]

Light snow falling between hardeman county and Memphis this morning on my way into work.  Pretty cool sight

[Holston_River_Rambler]

FYI, this is partly me trying to work through things so there may be more explanation than many of y'all need or want. But I also did a little more since I remember reading this type of stuff as a lurker and having no idea what it all meant, so I wanted to try to give some of those folks some explanation too. 

Time to take a magical mystery tour of tropical convection:

Western Hemisphere and Eastern Pacific:

Western hemisphere looks quiet, but the eastern Pacific is

The real action gets going across the western Pacific, the dreaded Maritime continent, and the eastern Indian Ocean to an extent:

 

Western Indian Ocean (I was kinda liking the pattern when it was there), is looking rather anemic too:

 

On the RMM plots* the above tropical convection state looks like this:

*(I know many of you know what these are, but if you are new or lurking and wondering what an RMM plot means: "Wheeler and Hendon (2004) constructed the RMM index for monitoring the MJO. This index consists of the first two principal components (PCs) of OLR, 850-hPa zonal wind, and 200-hPa zonal wind averaged 15S-15N". -definition taken from https://ncics.org/portfolio/monitor/mjo/rmm/ ) 

Why does tropical convection matter for the TN Valley you might ask. Well, where that convection thrives, it helps shape the jet to the north of it. JMA website(https://ds.data.jma.go.jp/tcc/tcc/products/clisys/anim/anim_tp.html) has a nice way to visualize this:

The above is the 30 day average. You can see most of the tropical forcing, indicated by the blue colors (less OLR), at least the average over the last 30 days, has been over the Indian Ocean Dipole (IOD). Those little magenta? arrows indicate where the air is moving at the jet level, 200 mb. 

Masiello had a good tweet illustrating this a while back:

 

Experience last year tells me that Maritime Continent convection and uplift usually means a strong Pacific jet aimed at the west coast of North America. Sure enough, for now, The Euro (RMM plot forecast above) sees the jet being pretty strong over the mid latitudes of east Asia, just north of where it sees the convection. You can even see a little bulge in that jet as the convections pushes on it.  

North of the equator, there are a few spots that have warmer than normal SSTs:

Still looks like there is something of an Indian Ocean Dipole (warmer in the west, cooler in the east), some warmish waters around the Maritime Continent, and the fabled Western Pacific Warm Pool (WPWP, took me forever to figure out that abbreviation). I'm guessing the warmer waters around Hawaii and in the Gulf of Alaska, are probably not triggering much convection. Those should be the favored areas for convection, at least over the ocean. One problem that we have in eastern N. America is that it is not always possible to get good convection in the same ways in more favorable areas, since S. America and Africa are landmasses and can't have sea surface anomalies. That doesn't mean they can't have convection, but I'm not sure you could get a standing IODish wave in the Amazon, since sea surface temps are always going to be more stable than land temps. I think this may be why those MJO correlation maps, are always much more sure about what a phase 7, for example, correlates to in the west than the eastern US (purples mean more confidence, source https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Temperature/readme.shtml):

There is much more confidence that a phase 6 = warm eastern US, than a phase 1 = cooler than normal eastern US.

Another way to look at tropical convection is velocity potential (labelled chi) at 200 mb.

Currently most of the above, is where you would expect:

Source for the above: http://mikeventrice.weebly.com/tropical-waves.html

But the Euro Control thinks we may have convection once again strengthen into the western Indian Ocean:

 

But the above is only one half of the equation. Go back and look at the EPS's depiction of the jet towards the end of its run. Notice the ridge trying to build into the arctic north of Alaska. You can visualize that another way:

At 500 mb in the North Pacific you can see the tropospheric PV in two parts here. One over Northern North America and the other over Siberia. The piece over Siberia acts like a wall and a pitcher. It acts like a wall in that it stops the progress of the energy and air the convection to its south is pushing north and also throws little bowling balls of energy at the west cast of North America.  It's like you create a funnel that forces air to move more quickly and then spins off a few blobs of vorticity as ridging attacks it. You get a few attempts to build a ridge into Alaska, but the TPV that's over North America keeps them supressed while the TPV over Siberia twirls any that make it, back around it as the ridging is shredded by the two. 

If you travelled on this mystery tour further up into the atmosphere, you'd arrive at a the Stratospheric Polar Vortex (duh...duh....DUHHHHH)

looking a little wobbly at the bottom, but stout higher up. But let's dissect it a bit more. A cross section reveals that the whole SPV is sort of titled to favor Eurasia with its presence. 

If I'm reading this map correctly, the purple core is the main SPV. But wait, there is also a core of cooler temps from the bottom up over North America. I think what we see here are the connections both 500mb PVs have to the much higher stratospheric PV. 

Below you can see how this looks on a more recognizable map. The reds are above average temp anomalies at 10 mb.  You can also see those on the above image as the reds and yellows in the upper right, while the greens and blues below are in the negative numbers in that cone I outlined in purple. The little bit of yellow and red above is what's left of the energy transport that gave us the -NAO. 

 

Subtle changes are all we need to get something better and the EPS shows some of that this AM:

Waaayyyy too much interaction now between the two TPVs I mentioned. Not only does it keep ridging out of Alaska and western North America, but it also helps reinforce the Pac jet. I do think it is interesting that there are still some attempts, anytime one of the two TPVs wobble, to shoot some ridging into Alaska. Maybe that is a base state we have seen so far this winter trying to take the reins? GEFS agrees that there will be some separation.

The real question now for me though, is: are there any actual clues in any of the real time observations above, that this could happen? After all, I think we are all on the same page this winter regarding models, even ensembles beyond 5 days or so, lol. 

In the less than fantasy range GEFS likes the idea of more convection in the western Indian Ocean which could help change up the jet configuration:

and the EPS likes it too:

But even if those changes happen, you still have to jet them percolate downstream to us, so like Carvers has been saying, maybe 3 weeks at best, assuming things do change upstream.

To me, after last year and for a pattern change if the Pac jet is bad, tropical convection is like the first lane of traffic if you are trying to turn into the second. You have to have it be clear there, before you can even think about turning across the highway. Now that doesn't guarantee that the other lane (N. Hemisphere blocking) will be clear, but you aren't going anywhere until that first lane clears. Hopefully some subtle shifts can pay dividends down the road. And we definitely have going for us that even when the convection gets over the Maritime Continent, it has never looked as robust as it did last year.

I feel like I've laid out the status quo pretty well, but maybe not done so well on analysis and forecast. i also maybe just wanted to give us a bunch of disparate pictures that might help visualize the current pattern at several different levels, to maybe help see a way out. Please add any and all things you think would help what I have here. 

 

 

 

 

 

[jaxjagman]

[jaxjagman]

MJO looks to be getting into the WH just after Christmas,not far off from what the RMMM's are showing

[AMZ8990]

6 hours ago, jaxjagman said:

MJO looks to be getting into the WH just after Christmas,not far off from what the RMMM's are showing

Jax-So is this when we think we could get some cooler temps back in the mix?  Or will it still have some work to do to get into cooler phases?  Bear with me cause the MJO/phases confuse me a lot of times 

[Carvers Gap]

The 12z EPS and GEPS maintain an eastern ridge throughout their runs...IMHO was a major step back today, especially for d10-15.  If there is any silver lining, the EPS looks nearly identical to the Weeklies which lift the trough out during week 2 temporarily and allow for a pretty severe cold shot.  Basically, the trough in the West connects to one over central Canada as depicted on the EPS.  The Weeklies then "yank" that trough out of their very quickly during week 1.  It is a very fast transition.  So what we want to see in the coming days is a progression like that.  I was worried when I didn't see the model moving up the eastern trough on the EPS...now it is just gone.  Let's hope the Weeklies are correct.  

The GEFS is out on a limb.  It has been handling the MJO very differently.  I frankly discount the model right now as an outlier.  That said, I think it is just too quick.  The progression is right, but too quick which is common for it...but it might be tipping its hand in a positive way.

One of my concerns is that western trough set-up seems to often take several weeks to break down.  I said 3-5 weeks from this past Monday...and I think we switch-up around the second week of January.  That said, if today's EPS is correct...I have concerns that the time for a cold transition is closer to 5 weeks than three weeks.  Major break(for the bad) in continuity today.

[weathertree4u]

Well, honestly, the last few years considered, my expectations are pretty low for anything different. I would think that we would get into a different pattern eventually, I mean it has been warm and wet wet and wet every season for several years now

[PowellVolz]

Looks like a little dry weather for the next week or so and by the first of next week a little AN temps. I mean... if there’s no chance at snow I’m ok with dry and almost seasonal temps. Play a little golf.


.

[John1122]

I'd as soon get the warm started and over with. Every year we have 2-5 weeks on and off with warm/cold it seems.  Though last year was more warm and more warm. I can't complain much so far. More snow already than the last two seasons and snow in the air again today. If the EPO goes negative as forecast that should open up more possiblites.  It'd be nice to get the PNA in decent shape for true winter too.

I always hold out hope for January 15th to February 15th as that is our best winter time frame. It takes the least amount of things going exactly right as we ever manage during that time frame. 

Even the best winters we've ever had in the area had at least 3 or 4 weeks of AN in winter. 

[Holston_River_Rambler]

Some other folks quoted Eric Webb today in saying that the EPS has a hard time seeing EPO ridges. Maybe we split the difference, add a few days on to the GEFS, but end up with something like what the GEFS showed at 18z by early January:

EPO, with a trough in the southwest slinging moisture at us, but also with a good cold air source? 

[TellicoWx]

Is it time to cancel winter and be done with it? Looks like we will be chasing unicorns all winter. If we have to content with a western trough, i think we should. 

Would I cancel winter...um no lol. Here's some data why (also fits with Carvers thinking of a back loaded winter). This is for TYS going back to 1910, and also supports why last year is completely different than this year. Comparing the temp data set from every year, only 7 currently correlate with this year when comparing low temps (this year Nov: 19, Dec: 27 barring a flip in modeling to end the year Dec will be closer to 23-24 as coldest recorded low).

 

Years with a similar +4 or higher spread from Nov to Dec (late Jan/Feb relation):

 

2014/15...Flipped Cold

1970/71...Flipped Cold

1959/60...Flipped Cold

1956/57...Continued Warmth

1950/51...Flipped Cold

1922/23...Flipped Cold

1911/12...Flipped Cold

 

So 6/7 (86%)...had a flip to cold.

 

Compared to last year (coldest low Nov: 21, Dec: 21...no chg). Winters where Nov to Dec had a +1/-1 variance:

 

2018/19..Flat trend/Warmth

2012/13...Flat trend

2011/12...Flat trend

1994/95...Flipped Cold

1991/92...Flipped Cold

1987/88...Flipped Cold

1979/80...Flat trend

1967/68...Flipped Cold

1940/41...Flat trend

1938/39...Flat trend

1928/29...Flat trend

1921/22...Flat trend

1913/14...Flat trend

 

So 4/13 (31%) only had some sort of cold pattern reshuffle.

 

Sent from my SM-S767VL using Tapatalk

 

 

 

[John1122]

GFS pops a +PNA in the long range.  Sets up major cross polar flow with cold air deep into the south and snow in the deep south. Has shown this a few runs in a row. Will see if it reels it in.   

[Carvers Gap]

Man...if the GEFS/GFS combo could score a coup just one freakin' time during mid--winter, this is the one!!!  That is a ball of fire in the North Atlantic at 500.  

I am with you, John.  Let's just get this over with...LOL.

Totally agree that some truly great winters have had wicked warmth in December.  

 

[Carvers Gap]

11 hours ago, Holston_River_Rambler said:

Some other folks quoted Eric Webb today in saying that the EPS has a hard time seeing EPO ridges. Maybe we split the difference, add a few days on to the GEFS, but end up with something like what the GEFS showed at 18z by early January:

EPO, with a trough in the southwest slinging moisture at us, but also with a good cold air source? 

I did see that...I would personally clean up his statement by saying the EPS has a hard time seeing cold regarding its 2m temp pattern any time of the year and also during shoulder season.  Its 500 pattern is very understandable given the nature of the convection in the eastern IO.  The GEFS is at the time of the year where it whiffs pretty badly.  I have noted, and USAF in the MA forum noted this tonight, that the GFS/GEFS sniffed out the cold in November first.  That said, it is a completely different time of year.  I think we turn cold by the second week of January as I think the GFS/GEFS is too quick and is an outlier among global models and their ensembles right now.  Bottom line:  In the d10-15 one model is going to be badly, badly incorrect on a pretty epic level - and I am not sharing a foxhole with the GEFS in a model war.  The GEFS has a chance of being right, but let's not forget that it has basically been cold for all of December during d10-15 and been woefully wrong.  TRI sits at +2.7 for December....not in torch territory but pretty close.  The GEFS never saw it coming.

[TellicoWx]

2 hours ago, Carvers Gap said:

I did see that...I would personally clean up his statement by saying the EPS has a hard time seeing cold regarding its 2m temp pattern any time of the year and also during shoulder season.  Its 500 pattern is very understandable given the nature of the convection in the eastern IO.  The GEFS is at the time of the year where it whiffs pretty badly.  I have noted, and USAF in the MA forum noted this tonight, that the GFS/GEFS sniffed out the cold in November first.  That said, it is a completely different time of year.  I think we turn cold by the second week of January as I think the GFS/GEFS is too quick and is an outlier among global models and their ensembles right now.  Bottom line:  In the d10-15 one model is going to be badly, badly incorrect on a pretty epic level - and I am not sharing a foxhole with the GEFS in a model war.  The GEFS has a chance of being right, but lets not forget that is has basically been cold for all of December during d10-15 and been woefully wrong.  TRI sits at +2.7 for December....not in torch territory but pretty close.  The GEFS never saw it coming.

I agree...think the GEFS is jumping the gun on the cold flip. Will be interesting to see if the EPS starts noticing anything in the 2/3 week of Jan. I think Feb will be interesting for the forum as it unfolds.

[Carvers Gap]

Some baby steps by the 0z EPS this AM...still a warm pattern but one can see how we might get out of it.   The thing that concerns me right now is that the trough inexplicably really wants to go into the West on the Euro Weeklies even after we cool down in early January.  The Weeklies are likely swinging wildly after week four, but we are at the time of year where the Euro Weeklies have some weight. The GEFS is way out on a limb.  I think this AM one could make a case that the EPS maybe moved towards the GEFS a hair.  That said, just when you think one model caves...everything goes haywire.  The GEFS is a much different solution and is juxtaposed the EPS. In the end I think the slower EPS is probably the right way to go, and that the GEFS has sniffed out a potential pattern change OR instead of a pattern change... just that the western trough/eastern ridge pattern relaxes for a week or so.  So right now(fingers crossed), looks like the first week of January is a transitional period...and the second week of January cold.  The third and fourth week of January are up for grabs.   Again, we need to really hope the GEFS is correct.  It is quicker by four or five days regarding the pattern change...but it has cried wolf for about four weeks so difficult to trust it.

[Holston_River_Rambler]

It would be intersting to see a spaghetti plot for the EPS. Weathermodels has it for the tropical cyclones, but not like the GEFS ones for 500mb:

I know most of you know what there are, but again, if you are new/ lurking, it shows three, 500 mb height levels as projected by each of the members of the GFS ensemble. 

You can see which members build that ridge and which ones don't. It's hard to tell which are which, but some have some cut offs rolling into the west coast. The mean also does like the idea of the Pac jet trying to undercut the ridge. 

Would be interesting on the EPS so you could see if even any members show that EPO ridge or not. 

 

[jaxjagman]

MJO has weak signals,even some the the Euro members and even the Euro for that matter seems to be hinting at the  MJO getting into phase 7 then looping right back into the Maritime the first of the year,have to wait and see.See a different look everyday

[Carvers Gap]

Looks like the Indian Ocean has re-fired...lots and lots and lots of convection.  That usually signals anomalous warmth over the eastern US down the line.  At this point, really getting tough to find any indicators outside of the ENSO state that favor cold in the East.  That said, I do think ENSO is a trump card...beats all others.  The MJO looks like both the American and Euro suites now like the idea of the MJO moving into phase 7 and stalling.  The EPS today did look a bit better.  The GEFS is its usual and biased Arctic self.  Overall, I think whatever cold shot we get in early January is now appearing as if will be a relaxation of the current warm pattern for eastern NA vs being a new base state cold pattern.  I still think we see winter...but man, really don't like seeing what is going on in the Indian Ocean.  That sunk us last winter.  I have said that the current warm pattern would last 3-5 weeks.  I think we see cold by the end of the first week of January...then the warmth returns for a significant amount of time.  I think by the end of January, we will see maybe two weeks of seasonal weather...the rest warm....just kicking around that idea.  January is a transitional month during Ninos and makes for a wicked tough month to get a handle on things.  If the MJO verifies...isotherm's forecast is money.  My confidence in seeing significant, sustained cold prior to February is pretty shaky.  I don't like banging the warm drum...climatology based on ENSO is about the only thing we have going for us.  The EPS, while it looks better, blocks cold from entering NA with low pressure at high latitudes.  So, we finally get the block...no source region - at least on today's model run.

[Carvers Gap]

So, the moral to that story^^^^, the Atlantic is our only hope.  Like that Star Wars tip of the hat?

[Carvers Gap]

And the 18z GEFS is why I will never share a foxhole with that model during a model war.  It caved to yesterday's EPS.  Today's 12z EPS doesn't look so bad.  They kid of sort of switched roles today...The EPS has made a natural progression to an eastern trough while the GEFS just flip flopped.  I actually thought the 12z EPS looked quite decent.   Now, the 18z GEFS should bring back some pretty bad memories.  Going to be a while before we get out of this pattern.

[weathertree4u]

18 minutes ago, Carvers Gap said:

And the 18z GEFS is why I will never share a foxhole with that model during a model war.  It caved to yesterday's EPS.  Today's 12z EPS doesn't look so bad.  They kid of sort of switched roles today...The EPS has made a natural progression to an eastern trough while the GEFS just flip flopped.  I actually thought the 12z EPS looked quite decent.   Now, the 18z GEFS should bring back some pretty bad memories.  Going to be a while before we get out of this pattern.

Paint me surprised!

[Holston_River_Rambler]

I don't know, I felt like we did ok, earlier in the season when the convection was in the western Indian Ocean.  Now the eastern IO has played not so nice, but if we're looking at the same thing, that convection looks west and to be moving more west. 

Wouldn't the western IO be phase 2? 

Still quite a bit over the Maritime Continent though:

Another thought (apologies if I messing this up): is the western Indian Ocean also being impacted by the Rossby wave Jax was talking about a few days ago? If so, that flare up may be temporary as it moves westward. 

Agree that the GEFS has done a typical GEFS flop. Even the spaghetti plots from the18z don't see anything like the EPO from only 12 hours ago:

I thought at first maybe it was seeing some new convection in the maritime continent:

But the GEFS had about the same thing as above 24 hours ago when it was showing the better 500 mb look.

EPS likes more western IO convection and then a gradual transition to western hemisphere convection. 

Trying to find the GEFS Hovmoller diagrams, but alas, I can't right now for a comparison to see if the way it sees the same variable has something to do with it's flop. 

 

Looking at the trend of the trend at 500 mb, looks like the GEFS has suddenly changed its mind on the NAO region as well, and that impacts the way it deals with the TPV in Canada, and that guides the flow over us:

[Carvers Gap]

1 hour ago, weathertree4u said:

Paint me surprised!

LOL.  No surprise at all....not that the EPS is much better during d10-15.  Unless we get a surprise, IMHO at least a couple of more weeks before we leave this hostile pattern.  

[Carvers Gap]

39 minutes ago, Holston_River_Rambler said:

I don't know, I felt like we did ok, earlier in the season when the convection was in the western Indian Ocean.  Now the eastern IO has played not so nice, but if we're looking at the same thing, that convection looks west and to be moving more west. 

Wouldn't the western IO be phase 2? 

Still quite a bit over the Maritime Continent though:

Another thought (apologies if I messing this up): is the western Indian Ocean also being impacted by the Rossby wave Jax was talking about a few days ago? If so, that flare up may be temporary as it moves westward. 

Agree that the GEFS has done a typical GEFS flop. Even the spaghetti plots from the18z don't see anything like the EPO from only 12 hours ago:

I thought at first maybe it was seeing some new convection in the maritime continent:

But the GEFS had about the same thing as above 24 hours ago when it was showing the better 500 mb look.

EPS likes more western IO convection and then a gradual transition to western hemisphere convection. 

Trying to find the GEFS Hovmoller diagrams, but alas, I can't right now for a comparison to see if the way it sees the same variable has something to do with it's flop. 

 

Looking at the trend of the trend at 500 mb, looks like the GEFS has suddenly changed its mind on the NAO region as well, and that impacts the way it deals with the TPV in Canada, and that guides the flow over us:

Changing wavelengths prevent a bad pattern from locking-in often during shoulder season.  Once the winter season settles-in, those drivers have a lot more strength.  

This is an ugly pattern coming up, but I think folks have been fairly warned for some time that multiple indices soured a couple of weeks ago.  This warm-up and its duration should be no surprise.  Nino winters generally start warm, sometimes very warm.  That is in my notes from June about winter.  Can't get more warning than that.  LOL.

Now, some don't like the 12z EPS.  Looks good to me as it lowers heights in the East.  We will get a temporary cold shot I think during the second week of January followed by more warm.  What is tough is that we all think about last year and worry about a repeat.  These Nino winters can and do flip on a dime, and they don't care about past statistics.  I fully expect a flip to happen similar to what happened during fall.  It gets old repeating that flips do happen, especially last year when it didn't happen at all.  That said, I still suspect we see a very sharp reversal at some point...but make no mistake, we have plenty of warm weather before we get there.  But it is always wise to remember, some of our best winters were had after VERY warm starts to winter, even including large portions of January.  Might happen and might not this winter...but I can just about guarantee we will see multiple( great winters during the future that begin warm.