Winter 2019-20 Preseason Discussion

[Maestrobjwa]

16 minutes ago, showmethesnow said:

One thing I will keep an eye on in the coming weeks will be the central pac. What we have seen in the enso region is a move towards a modoki style sst temp profile with some good neg temp anomalies migrating westward from s America and IOD induced cooling moving eastward from the western Pacific. And in the middle, 3.4 and 4 regions, we are seeing the warm water piling up. Now why this is important is that this will provide the contrast needed to provide the focus for our tropical forcings. In fact I do think we are probably beginning to see the effects of this enso forcing as we are now seeing what looks to be a cold pool beginning to form to the north in the central/western pac. This is what I would expect to see. From what I am seeing I think indications are pretty good that this modoki profile would last at least until the first part of winter.  IF... I am correct on the above (starting to feel somewhat confident) that potentially bodes well for our chances for at least the first half of winter.

HM seems to think the Modoki is real this time as well:

 

[poolz1]

Both the gefs and eps have shown hints at a scan ridge developing in the LR. Still a little muted in the means but some runs are more robust than others. Gefs heights at 10mb show a strengthening PV but you can start to see the squeeze/elongation. Something to watch. Maybe our first jab?

[frd]

54 minutes ago, poolz1 said:

Both the gefs and eps have shown hints at a scan ridge developing in the LR. Still a little muted in the means but some runs are more robust than others. Gefs heights at 10mb show a strengthening PV but you can start to see the squeeze/elongation. Something to watch. Maybe our first jab?

Hey @poolz1     are you familiar with AAM, angular momentum ?

 I read a post at a another board from a good contributor and he mentioned we are still , momentum wise no where near a Modoki Nino .  He stated momentum is very low and even with typhoons and other features it remains low.  The person made some valid points.  i think this was the same issue last year.  

I wish  HM would for once post here and give a brief explanation instead of just the twitter world.

 

[frd]

A little more on snow cover advance last week via member bring back 62-63 from 33andrain 

 

<<<

Now this "temp trend" is a key chart, particularly early on in the re-freeze season. This allows for the rapidly falling "mean" temps during October. If all else was equal (which it never is!) the whole chart would be blue!  Again, most of the Atlantic side of the Arctic will see steady short term cooling. Interesting that much of central/northern Siberia will see a warmer period following the cold and early snow accumulation there (more below on that).  Contrast that with the top chart.  The deeper cold is shifting to north and west Russia and good to see northern Greenland getting very cold. The pressure charts for the next week to 10 days (not shown) show a mix of HP ridges and relatively weak LPs with no serious WAA and no major storms in the Arctic.  Overall, although the re-freeze will slow down on the far side, much of the rest of the Arctic should see the rate increase substantially and that curve on the graph (top chart) "should" see a steady rise during the next few days. Let's hope that the recovery rate continues to rise during the second half of October. 

 

Last Sunday I posted the Siberian snow cover extent (see chart copied below) and the chart above shows that this has continued to increase - in fact it paused for a few days and then resumed its steady spread south westwards. Given the higher temps expected in Siberia this coming week, I would expect little further growth in Siberia but with much of northern and western Russia becoming very cold and an LP system pushing eastward through Russia around mid week we should see substantial snowfall there and the main snow area should expand steadily westwards. This will lead to the Eurasian snow cover being well ahead of normal for mid to later October.

 

Overall it is a very mixed picture but with no cause for extreme pessimism at this stage.  Displaced Arctic cold may provide lower temps in North America and Eurasia but it is bad news for the Arctic. The consequences for the impacts on ocean-atmosphere interaction and disconnects and changes to the jet stream are the subject of a great deal of research and no firm conclusions are yet available. I will place more of the recent papers on this into the Research Portal in the coming weeks and then I'll review the most relevant ones in several post

>>>

 

[poolz1]

Hey [mention=9853]poolz1[/mention]     are you familiar with AAM, angular momentum ?
 I read a post at a another board from a good contributor and he mentioned we are still , momentum wise no where near a Modoki Nino .  He stated momentum is very low and even with typhoons and other features it remains low.  The person made some valid points.  i think this was the same issue last year.  
I wish  HM would for once post here and give a brief explanation instead of just the twitter world.
 

Very familiar with the term but honestly have very little knowledge of the effects. Iirc, a low AAM is more indicative of a Nina state? Maybe I should do some reading!

I feel like every year I add another piece of knowledge...may this year it will be understanding AAM. By the time I’m 90 I should be able to hang with some of the other posters in here. Lol

[frd]

An interesting older article on AAM .  Some things included in the article are the Nina connection, wind fields and  workings if it . Some cool images too. 

 

https://climateimpactcompany.com/wham-bam-aam-explains-hostile-global-weather-january-2018/

 

[frd]

10 minutes ago, poolz1 said:

Very familiar with the term but honestly have very little knowledge of the effects. Iirc, a low AAM is more indicative of a Nina state? Maybe I should do some reading!

I feel like every year I add another piece of knowledge...may this year it will be understanding AAM. By the time I’m 90 I should be able to hang with some of the other posters in here. Lol

Ha ha your funny!  Yes the low AAM state is more Nina like. So the talk was about the  AAM state. 

I know Ventrice talks about in the winter as does HM, and others.  Seems to add a spark  to the atmosphere as well. 

The link in the article above  talks about it and is interesting. 

To thicken the plot though I read that there have been winters in the East that were cold and snowy with a low AAM.  However these winters  were many years ago, not sure whether they can add value now in this day and age.

For example, this came across my mind regarding the the great winter of 95-96 which was a Nina wondering what the AAM would have been then ? 

I imagine you also have to think about the Pac in years before 95 -96 as well. What was that Nina following up on. I know that enters the outcome as well. 

The Nina state would suggest a low AAM state but was it?   I am sure too the lower solar cycle at this time and the QBO were at play as well. 

 

[frd]

Speaking of AAM

 

 

 

[showmethesnow]

Now we are starting to talk. Models are starting to pick up on the idea of good ridging up the west coast into Canada. Also see hints of troughing/weakness undercutting this ridging in the SW in the southern flow. Western Alaska/aleutian troughing is also in the equation. Pretty Sweet look as far as the PAC and the flow through the CONUS is responding accordingly. Western Atlantic up into the nao domain still has some work to be done but we are seeing the East coast ridging/WAR breaking down and/or migrating towards Greenland which is a hell of a good start in getting the Atlantic to cooperate. 

For the beginning of November you couldn't ask for more. Hopefully we are seeing the base state of the PAC of which after any temporary breakdowns we will return to. If so I would like our chances for at least the first half of winter. But you know then drill, models at the end of the extended... 

[frd]

3 hours ago, showmethesnow said:

For the beginning of November you couldn't ask for more. Hopefully we are seeing the base state of the PAC of which after any temporary breakdowns we will return to. If so I would like our chances for at least the first half of winter. But you know then drill, models at the end of the extended... 

Looks Pac driven, which is great, if it continues all winter, because the continued theme for the NAO from the seasonal models is positive.  That's not going to help us down here. 

 

 

[frd]

Here is an interesting piece of information ......  

Now keep in mind this is for the NYC metro area but I would think the same general results would hold for our geographic area as well. 

This is from Don S., the master of weather stats

The take away here is if you are hoping for cold winter we better get a cold November. 

As Don  mentions the association with snow is a little more mixed.  Location:New York  Posted yesterday at 08:57 AM

  On 10/13/2019 at 4:10 AM, LibertyBell said:

Don, when both October and November are above normal temps, the following winters are mild and snowless most of the time, right?

 

From Don S. 

It is typically a signal of a warmer winter.

Since 1980, the following has occurred in New York City when both October and November were warmer than normal:

Succeeding winter:
Colder than normal: 3/13 (23%) cases
Near normal: 1/13 (8%) cases
Warmer than normal: 9/13 (69%) cases

Breakdown of months:

December:
Colder than normal: 4/13 (31%) months
Warmer than normal: 9/13 (69%) months

January:
Colder than normal: 2/13 (15%) months
Warmer than normal: 11/13 (85%) months

February:
Colder than normal: 2/13 (15%) months
Warmer than normal: 11/13 (85%) months

December-February:
Colder than normal months: 8/39 (21%) months
Warmer than normal months: 31/39 (79%) months

The snowfall signal was mixed.

Mean: 24.2"
Median: 24.9"

Lowest: 3.5", 2001-02
Highest: 61.9", 2010-11

 

[psuhoffman]

On 10/10/2019 at 6:10 AM, showmethesnow said:

Think I would probably fine tune the years he has. At this time I think odds are pretty good we are looking at a warm neutral ENSO. So giving a spread of a cold neutral to a weak Nino that weeds out 5 of those years. 2003 is a moderate Nino. 2000 is a weak Nina that is coming off a strong Nina base state. 1996 is a border line Moderate Nina. 1965 is a weak Nina. 1956 is a border line strong Nina. 

So going with the remaining years gives us this.

 

Not a bad look with plenty of blocking in the NAO domain. Also like seeing the lower heights in the 50/50 region giving us the -NAO/50/50 combo. Hesitate a little when I see the lower height anomalies in the SW but the western based NAO should hopefully help on occasion to keep systems underneath us. Not a particularly cold look and one that will probably mean variable weather for our region as the NAO waxes and wanes. Looking at the individual years the blocking in and around the NAO is a dominate theme. But we are seeing quite a bit of variability in the eastern Pacific (EPO, PNA, Aleutian low). Not really enamored with the general idea of the flow through the states on most members though. With the general look being presented our snow chances will be highly dependent on seeing good blocking in the NAO domain down through central/southern eastern Canada or a -NAO/50/50 combo.

 

On 10/10/2019 at 7:33 AM, C.A.P.E. said:

Yeah I am not crazy about that look in general, minus the NA block. Long wave pattern is a bit out of phase for what we want. Not awful, but with the EPAC ridging displaced that far west, there would be a tendency for a trough out west and a SE ridge. We would really need the -NAO to be west based and strong.

Sorry it took me so long to post on this... been really busy lately and just started looking at winter a little.  I agree that further refinement of these years would be needed...but I think the point of this does show that our current QBO is a positive factor.  Other variables could shift...so could the QBO if it fails to continue to decline as expected, but overall if we look at all the years with a similar QBO progression they ranged from "run of the mill" normal winters to blockbusters.  None were total dud years imo.  CAPE, your concern looking at the H5 is valid but if we look at the actual results its not as bad.  Sometimes a long duration mean like that can hide details.  The worst was probably 2007 but that year included wasting the first half with a god awful pac pattern, and then getting pretty unlucky with several good opportunities the second half.  2005 could have easily been a much better result too with some luck.  So in the last the QBO would argue that this shouldn't be one of the really truly dreadful years.  It is always nice to eliminate those from the range of possibilities.  However, with such small sample sizes there is always the chance that such a result is well within the goalposts and we just haven't had one yet.  Count me in the group that thinks using older analogs is becoming increasingly problematic due to changes in the base state of the climate and SST's.  The pac is a raging inferno now compared to 50 years ago.  I think that is likely making the typical enso atmospheric response less reliable in years without a very strong signal.  So perhaps looking at the whole scope of QBO analogs isnt a bad idea.  Of course...the more recent analogs are the less inspiring of the cohort so that isnt as encouraging.  The other signals right now are very conflicting.  I have never had less of an opinion going into a winter as I do right now.  Maybe that is my own over reaction to last year, but I wouldn't be shocked by either a total dud non winter or a blockbuster or anything in between.  I can see valid arguments to support any of those outcomes depending on what factor you think is most important and will dominate.  Statistics and probabilities would argue the lower end of the range of possibilities is favored simple using climo of course.  

[frd]

11 minutes ago, psuhoffman said:

Count me in the group that thinks using older analogs is becoming increasingly problematic due to changes in the base state of the climate and SST's.

Yep,  relative climo is indeed changing. 

 

[frd]

This is cool about the NAO

2 takeaways for me   :

1 Low solar backdrop does indeed play a role in the weather , as you can see below from HM's post  

2 Low solar min seems to have an effect on the NAO but more so on a lagged time scale ,

 

 

 

[Maestrobjwa]

1 hour ago, frd said:

This is cool about the NAO

2 takeaways for me   :

1 Low solar backdrop does indeed play a role in the weather , as you can see below from HM's post  

2 Low solar min seems to have an effect on the NAO but more so on a lagged time scale ,

 

 

 

I've heard others mention this "lag" effect as well...I've been wondering if any NAO benefits from this minimum would come this winter or...if we would have to wait fot the following one (and how long would this "lag" be? Or would the low solar of last year now influence this year? Eh, I'm confused about this...lol)

[frd]

To balance the goods and the bad this most likely goes in the bad column. 

Sea ice for this date is the lowest it has ever been. I would think less ice formation would equate to less build up of cold air. 

That would likely be a poor factor in the creation of a robust cryosphere where cold air builds up and becomes colder and colder over time and then moving South given the impedance. Just my own thoughts here. 

However , there is great post on 33andrain from  member Bring Back who composed an excellent summary on the topic.

 

Here is a brief updated post by Bring Back and the link further down to an in-depth article he composed on sea ice.

From Don S 

Arctic sea ice extent has now fallen below the 2012 figure...

 

On account of abnormally slow sea ice growth, Arctic sea ice extent on October 13, 2019 had slipped below the 2012 amount. In 2019, Arctic sea ice extent was 4.881 million square kilometers on JAXA. In 2012, it was 4.912 million square kilometers.

<<<

From Bring Back 

Don,  yes 2019 is currently at the lowest extent on record (for mid-October) at this early stage of the re-freeze season.  I did an "Arctic Update" on the 2019-20 Winter Discussion/Forecast Thread yesterday and went into the reasons for this.  I am not as pessimistic as some commentators and expect the re-freeze rate to increase substantially during this week and into next week, particularly on the Atlantic side of the Arctic which has seen very little growth at all so far.  Here's the link to that post:

 ( I believe you will have to copy and paste into your browser )

 https://www.33andrain.com/topic/1710-2019-20-winter-discussionforecast-thread/?do=findComment&comment=153515 

 

[showmethesnow]

6 hours ago, psuhoffman said:

... I agree that further refinement of these years would be needed...but I think the point of this does show that our current QBO is a positive factor.

...other signals right now are very conflicting.  I have never had less of an opinion going into a winter as I do right now.  Maybe that is my own over reaction to last year, but I wouldn't be shocked by either a total dud non winter or a blockbuster or anything in between...

The years I did weed out went counter to what we saw with the years that had a somewhat comparable enso state. Not going to go back and check but I believe we saw a very strong +ao with two and the other three were showing the high latitude blocking popping elsewhere. But as you said we are talking such small sample sizes a lot of what we think we know about the qbo can probably be considered speculation more then anything else.

I'm with you. I have no idea what  to expect as well. As I mentioned in an earlier post there are quite a few conflicting signals at this time in my mind and depending on which direction you look we are talking either boom  or bust or anything in between. Think the next month though should give us some better clarity. 

[Maestrobjwa]

5 hours ago, psuhoffman said:

Count me in the group that thinks using older analogs is becoming increasingly problematic due to changes in the base state of the climate and SST's.  The pac is a raging inferno now compared to 50 years ago.  I think that is likely making the typical enso atmospheric response less reliable in years without a very strong signal.  So perhaps looking at the whole scope of QBO analogs isnt a bad idea.  Of course...the more recent analogs are the less inspiring of the cohort so that isnt as encouragi

Do ya think this means that, going forward...we may be less likely to be able to score in weak nino/neutral winters than in decades past? (with all the talk about the issue in the pac...I'm wondering if that means the neutral weak nino winters are bound to look more like last year, and that we'd only be able to score in moderate/strong ninos? Oof...we'd see fewer snowy years if we always had to wait for those to come around, lol)

[showmethesnow]

6 hours ago, frd said:

Looks Pac driven, which is great, if it continues all winter, because the continued theme for the NAO from the seasonal models is positive.  That's not going to help us down here. 

 

Yeah it would be nice to have a cooperative pac. Makes it so much more forgiving if we do see a lack of blocking. But I am not so sure I would give up on the idea of a predominantly -nao regime this winter. I am leaning somewhat towards this myself. As often is the case in recent years it may come down to the models not picking up on it until it is on our doorstep. 

[frd]

7 minutes ago, showmethesnow said:

Yeah it would be nice to have a cooperative pac. Makes it so much more forgiving if we do see a lack of blocking. But I am not so sure I would give up on the idea of a predominantly -nao regime this winter. I am leaning somewhat towards this myself. As often is the case in recent years it may come down to the models not picking up on it until it is on our doorstep. 

The models are certainly keying in on something and that something may very well be the extreme + IOD.

Are they resolving the future outcome correctly, hard to say , but the  general consensus among the models is pretty remarkable, in that a likely a +NAO will occur. 

Now are the model correct? Not sure as indications seem to reveal the extreme + IOD may decline soon and continue to weaken through the winter. 

 

@showmethesnow wanted to add there is some research out there does point to a averaged -NAO for the period DJF.

 

[BTRWx's Thanks Giving]

7 hours ago, frd said:

Here is an interesting piece of information ......  

Now keep in mind this is for the NYC metro area but I would think the same general results would hold for our geographic area as well. 

This is from Don S., the master of weather stats

The take away here is if you are hoping for cold winter we better get a cold November. 

As Don  mentions the association with snow is a little more mixed.  Location:New York  Posted yesterday at 08:57 AM

  On 10/13/2019 at 4:10 AM, LibertyBell said:

Don, when both October and November are above normal temps, the following winters are mild and snowless most of the time, right?

 

From Don S. 

It is typically a signal of a warmer winter.

Since 1980, the following has occurred in New York City when both October and November were warmer than normal:

Succeeding winter:
Colder than normal: 3/13 (23%) cases
Near normal: 1/13 (8%) cases
Warmer than normal: 9/13 (69%) cases

Breakdown of months:

December:
Colder than normal: 4/13 (31%) months
Warmer than normal: 9/13 (69%) months

January:
Colder than normal: 2/13 (15%) months
Warmer than normal: 11/13 (85%) months

February:
Colder than normal: 2/13 (15%) months
Warmer than normal: 11/13 (85%) months

December-February:
Colder than normal months: 8/39 (21%) months
Warmer than normal months: 31/39 (79%) months

The snowfall signal was mixed.

Mean: 24.2"
Median: 24.9"

Lowest: 3.5", 2001-02
Highest: 61.9", 2010-11

 

Who cares about NYC? lol

[Maestrobjwa]

On 10/14/2019 at 9:51 AM, frd said:

Looks Pac driven, which is great, if it continues all winter, because the continued theme for the NAO from the seasonal models is positive.  That's not going to help us down here. 

 

 

Dang...so what would this be? Almost ten years since a -NAO in the winter? (I remember the discussion about it possibly being on a decadal cycle or something like that) Smh And if the pac is gonna be less reliable overall because of climate...what else can we rely on?

[CAPE]

Fwiw, recent runs of the CFS have a solid +AO/+NAO look through at least January. No hints of HL blocking on our side of the globe. Luckily the Pacific looks decent, and ofc in another day or 2 the model may offer up something different lol. CanSIPS has been steadfast with the HL blocky look. In another couple weeks we can see if that holds as we move closer to the start of winter.

[poolz1]

The look advertised in the long range is reminiscent of 13/14... which is one of the analogs being thrown around if I'm not mistaken. Not much help in the NAO region but plenty of help on the PAC side.

Although, I'll take the 06z gefs to start Dec for 800 Alex. Looking ripe....

Sent from my SM-G973U using Tapatalk

[CAPE]

The latest runs of the GEFS,  EPS. and even the GEPS have a HL blocky look developing as we approach the month of November, very similar to what the CanSIPS has been advertising for that period(and persisting through winter) going back to it's August run.  Interesting. Maybe it is on to something. Given what the other climate/seasonal models are depicting currently, I like seeing the major global ensemble means all trending towards the CIPS idea heading into late fall.

[frd]

3 minutes ago, C.A.P.E. said:

The latest runs of the GEFS,  EPS. and even the GEPS have a HL blocky look developing as we approach the month of November, very similar to what the CanSIPS has been advertising for that period(and persisting through winter) going back to it's August run.  Interesting. Maybe it is on to something. Given what the other climate/seasonal models are depicting currently, I like seeing the major global ensemble means all trending that way heading into late fall.

Maybe the old saying should be , the weather in November the winter will remember, versus,  December. Mostly because lately Decembers have  sucked !  And then the following winter also sucked.

So let's go Cold and active November !!!! Yeah baby 

 

 

[CAPE]

1 hour ago, frd said:

Maybe the old saying should be , the weather in November the winter will remember, versus,  December. Mostly because lately Decembers have  sucked !  And then the following winter also sucked.

So let's go Cold and active November !!!! Yeah baby 

 

 

I am looking for positive signs in these climate/seasonals, and right now the CanSIPS is about the only one offering a very favorable h5 pattern for the MA region. For 3 straight runs it has developed the HL blocking during the October into November period, and it only gets better moving forward. So I will take it as a positive sign at this juncture that the global means are now advertising the very look it has been consistently depicting, and in the same time frame. Ofc it very well could mean nothing lol.

Pretty close match between the 0z EPS at the end of its run and what the CanSIPS has been advertising for that general period..

[psuhoffman]

21 hours ago, Maestrobjwa said:

Do ya think this means that, going forward...we may be less likely to be able to score in weak nino/neutral winters than in decades past? (with all the talk about the issue in the pac...I'm wondering if that means the neutral weak nino winters are bound to look more like last year, and that we'd only be able to score in moderate/strong ninos? Oof...we'd see fewer snowy years if we always had to wait for those to come around, lol)

Not exactly.  First of all last winter was a normal winter, and actually better than 50% of them in the urban corridor.  It would have been perfectly acceptable to MOST (sorry CAPE) had it not been for our inflated expectations due to the favorable enso look.  On top of that we have had plenty of great winters in neutral enso years, and even a few rare ones in nina years.  So I am most definitely NOT saying we will only score a snowy winter in stronger nino years.  

As for a weak nino specifically... that also depends on other factors.  I am just saying that a warmer base state of the PAC SST  in general may mute the impact of a weak nino.  And all analogs from more than 30 years ago should be taken with a grain of salt as we are in a vastly different climate regime now.  But if a weak nino acts more like a nuetral that still doesnt mean we can't get snow, just means weak nino's will be more dependent on other factors.  Last year the MJO and QBO didn't really help us out any.  Both stayed in phases not helpful to blocking or an eastern trough much of the winter.  And yet we still managed a decent winter regardless, just a letdown compared to our lofty expectations.  This year with a neutralish enso we are again at the mercy of other factors and right now those other factors are in conflicting states.  Some favorable, some not.  To me that probably means a variable winter with some chances but not wall to wall awful and not wall to wall good either.  If we simply use climo that probably means about 9-18" in the urban corridor with a bit more NW and a bit less SE.  That is simply going with a straight climo expectation of what a "typical" winter is for our area.  DCA median snowfall is about 10", BWI about 15 and IAD about 16.   If the positive factors like the QBO end up dominant perhaps we end up with a better result than that, but its hard to predict above normal snowfall here when we typically only get 3/10 above normal winters and the signals are mixed going in.  But we have had plenty of snowy winters that weren't expected to be such at this point.  

[psuhoffman]

21 hours ago, Maestrobjwa said:

Do ya think this means that, going forward...we may be less likely to be able to score in weak nino/neutral winters than in decades past? (with all the talk about the issue in the pac...I'm wondering if that means the neutral weak nino winters are bound to look more like last year, and that we'd only be able to score in moderate/strong ninos? Oof...we'd see fewer snowy years if we always had to wait for those to come around, lol)

This might help, this is BWI snowfall broken down by enso state years.  You can see that neutral actually has a slightly higher mean/median snowfall than weak nino.  The adjusted average is with any obvious outliers taken out.  This chart helps give you a quick snapshot of how we perform by enso category.  But I would take some of the older years in this set with a grain of salt now.  Of course the problem is if we start to only look at the last 30 years we end up with too small a sample size for each enso state to have a significant data set.  Catch 22 

[poolz1]

Going to be wild ride in the LR if anything close the 12z gfs op run comes to fruition. Monster heights over Greenland. gefs agree with the look...as far as ensembles go.