• Member Statistics

    16,681
    Total Members
    7,904
    Most Online
    zurn
    Newest Member
    zurn
    Joined
Sign in to follow this  
WxUSAF

Winter 2019-20 Preseason Discussion

Recommended Posts

Very end of the 12z GFS got everyone into the thirties... first freeze in the western areas of the forum. Light snowfall in a bit of the Apps.

 

Heck, 12z has a coastal somewhat near the coast. Makes me almost want to renew my WeatherBell subscription to see if any of the ensembles bring that into play. ;)

Share this post


Link to post
Share on other sites

Recent runs of the CFS seem to be coming around to the CanSIPS idea of a favorable EPAC and building +h5 heights up top, with lower heights in the east. November is just a few weeks away.. Maybe an early season high elevation snowfall not out of the question.

cfs.thumb.png.7b7d8e3957c3fa1bf9ae1b6dbc25dbce.png

cans.thumb.png.69303e31b79d13b8f77602090854391e.png

Share this post


Link to post
Share on other sites
10 hours ago, BTRWx's Thanks Giving said:

Am I allowed to share my own blog analyses here?  I'll relocate it if not.  What analogs do you all see? https://btrwxweather.blogspot.com/2019/10/btrwxs-2019-2020-winter-outlook-analyses.html?fbclid=IwAR2zqRcrr3mcWVGA39NpP-u6lWxRbeiPg46D0xrY4848VXaSpmuszHBsaIs

Not really sure the 3 years you threw up (04-05, 14-15, 18-19) are a good match. Just looking at the 3 month mean (dec-feb) they differ quite a bite. If you look in the key areas, the domains (NAO, AO, PNA, etc..) we are seeing some extreme differences in values. And these differences are even more notable when you compare month to month. So I am not so sure what value blending the 3 years together really has especially when it is such a small sample size.

This plot is not dissimilar to the PNA

This plot is not dissimilar to the PNA

This plot is not dissimilar to the PNA

 

While I agree focusing on the Pacific is key as in most years it is the main driver, I am not so sure that just the general overall SST look through the whole basin is where I would begin or even base my whole outlook on. There is a good reason that people focus first and foremost on the ENSO domain. Now while the ONI values are somewhat similar between these years,  notice the SST distribution along the equator through the ENSO region and how they differ. With these differing looks we are seeing different forcings that are affecting the Walker Cell strength and location within the Pacific (see modoki nino as an example). This Walker cell setup is probably the key thing that should be focused on. So if you want to focus on SST distribution I would probably start there and then work out to the secondary areas (warm blob, IOD, etc...) of importance and then use the general overall SST's as a fine tuning. Now considering that we are discussing the winter weather for the Atlantic I am not so sure I would also totally ignore the other secondary drivers downstream. Though not often, we do see on a occasion where they do trump the PAC (such as a strong -NAO). Even when they don't override the PAC they do add nuances to the pattern through our region that can make or break us as most years we are living on the edge. 

  • Like 1

Share this post


Link to post
Share on other sites
44 minutes ago, showmethesnow said:

This Walker cell setup is probably the key thing that should be focused on

Nice post. 

Seems we are faced with various extreme drivers of the pattern the last several years and how they interact  together, or which takes over if you will, gives us our sensible weather. 

Many unknowns at this time still.  How will the extreme + IOD effect the winter, what about the tropical forcing and the progression of the QBO. 

So much to think about. Very fascinating. I liked the way Isotherm describes his method of looking at the future weather and it truly is a multi-step process with one step determining the next and then weighing things out and knowing what to choose and what not too.    

  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites

SOI continues its negative run (after a few days of pos). MJO is meandering in 8/1. Once that Aleutian trough forms in the LR...it sure is an El Niño look across the N Hem.

Share this post


Link to post
Share on other sites
1 minute ago, poolz1 said:

SOI continues its negative run (after a few days of pos). MJO is meandering in 8/1. Once that Aleutian trough forms in the LR...it sure is an El Niño look across the N Hem.
 

The EPS concurs or should I say it did as of yesterday.  

Share this post


Link to post
Share on other sites
7 minutes ago, frd said:

There are differences as you mention  @showmethesnow in the Pac 

Take this for example below as posted by Ben

 

 

Been looking over the PAC the last week or so. Tending to favor a warm neutral to a borderline weak nino at this time. Now whether we see a Modoki style setup with the SSTs is still up in the air at this time though I do lean in that direction somewhat. Think that will become much clearer in the next few weeks. Wild card may be the IOD and its interaction with ENSO and I don't know nearly enough about the interplay. Want to look at some analogs between those two in the coming days to get a better feel.

Share this post


Link to post
Share on other sites
5 minutes ago, poolz1 said:

SOI continues its negative run (after a few days of pos). MJO is meandering in 8/1. Once that Aleutian trough forms in the LR...it sure is an El Niño look across the N Hem.
 

Like seeing that setup being thrown up in the longer ranges though to be picky I would like to see it a little farther SW. Was also noticing that though we are seeing a fairly strong pv in the strat (10 mb) centered over the pole it is taking a noticeable slant top down through 500 mb to the surface towards western Alaska/Aleutians. Nice to see and will help to mitigate the strengthening of the pv.

  • Like 1

Share this post


Link to post
Share on other sites
4 minutes ago, showmethesnow said:

Been looking over the PAC the last week or so. Tending to favor a warm neutral to a borderline weak nino at this time. Now whether we see a Modoki style setup with the SSTs is still up in the air at this time though I do lean in that direction somewhat. Think that will become much clearer in the next few weeks. Wild card may be the IOD and its interaction with ENSO and I don't know nearly enough about the interplay. Want to look at some analogs between those two in the coming days to get a better feel.

Your thoughts echo some others ,  I believe Benchmark's possibly. He even thinks a  marginal weak Nino is possible. 

I did read Raindance who posts on the Nino extensively mentioning Nino 4 corresponds to a warm December in the East, I was not aware of this. 

But, again,  are other players going to appear to maybe shake things up in December to make it colder. Time will tell. 

from raindance 

These are the closest Nino 4 years for September (29.1C-29.5C). They are all El Ninos - but keep in mind Nino 4 is warming much more rapidly than the other Nino zones. That's part of why you guys in the East have had such trouble getting a cold December since Nino 4 is correlated to December in the East for temps. 1989-2018 Septembers in Nino 4 are 28.75C on average, compared to 28.11C in 1950-1979. If the 2017 Nino 4 reading was applied to the older average, it'd be +0.6C, but a La Nina still developed, one that had the coldest Nino 1.2 readings for a while: 30 to 40 years in several months. My interpretation is if we had data for 2005-2035 in Nino 4, you'd find it was only +0.2C, instead of +0.55C. There are plenty of years when Nino 4 is +0.2C against the "centered climate average", that do not become El Ninos.

 

Share this post


Link to post
Share on other sites

@showmethesnow might make sense to focus on PMM as well 

Excellent read to learn more 

https://www.climate.gov/news-features/blogs/enso/your-eight-minute-speed-date-pacific-meridional-mode

 

To me this is a sensible post brought over form 33andrain from member Oglem 

Posted 11 hours ago

Hey everybody, I just wanted to say thank you for sharing information on analogs, it really helped me out. I took a look for years with similar PMM and ENSO. I found 6 years with Jun-Jul-Aug PMM > 4, and they were 1958, 1967, 1986, 1992, 1994, and 2016. 1986 and 1994 were moderate nino winters, so I removed them since this winter is likely going to be a neutral/borderline weak nino winter, although 1994 wasn't too far into moderate territory. Here's the result:

 

image.png.3100c50a6b2e65732c8fa65b84fc4938.png

Looks like the core of the cold will be in the Upper Midwest, with some cold in the NE and a SE ridge flexing a little bit too. This is only looking at PMM/ENSO, though. Assuming the PMM stays positive, it has the strongest correlation coefficient for the Northeast and Southwest, so it does seem like it would contribute to cold in the NE. Additionally, the PMM is related to Central Pacific warming, so it should be a factor in our favor going into the winter .

Share this post


Link to post
Share on other sites

@showmethesnow  in regards to the above and the PMM this post mentions how the PMM provides different outcomes once we head deeper into the Fall season and the wavelengths lengthen. 

This progression,  should it hold,  will yield a very cold December.

 

December 

 

Image

 

 

 

 

 

  • Like 1

Share this post


Link to post
Share on other sites
59 minutes ago, frd said:

 

These are the closest Nino 4 years for September (29.1C-29.5C). They are all El Ninos - but keep in mind Nino 4 is warming much more rapidly than the other Nino zones. That's part of why you guys in the East have had such trouble getting a cold December since Nino 4 is correlated to December in the East for temps. 1989-2018 Septembers in Nino 4 are 28.75C on average, compared to 28.11C in 1950-1979. If the 2017 Nino 4 reading was applied to the older average, it'd be +0.6C, but a La Nina still developed, one that had the coldest Nino 1.2 readings for a while: 30 to 40 years in several months. My interpretation is if we had data for 2005-2035 in Nino 4, you'd find it was only +0.2C, instead of +0.55C. There are plenty of years when Nino 4 is +0.2C against the "centered climate average", that do not become El Ninos.

 

I'll have to look into the PMM. Not really familiar with it. Out of curiosity, what years is he talking about? 

Share this post


Link to post
Share on other sites
15 minutes ago, showmethesnow said:

I'll have to look into the PMM. Not really familiar with it. Out of curiosity, what years is he talking about? 

The post dealing with PMM he mentions the closet matches are :

67-68

59-60

16-17

92-93 

Share this post


Link to post
Share on other sites
4 hours ago, showmethesnow said:

Not really sure the 3 years you threw up (04-05, 14-15, 18-19) are a good match. Just looking at the 3 month mean (dec-feb) they differ quite a bite. If you look in the key areas, the domains (NAO, AO, PNA, etc..) we are seeing some extreme differences in values. And these differences are even more notable when you compare month to month. So I am not so sure what value blending the 3 years together really has especially when it is such a small sample size.

This plot is not dissimilar to the PNA

This plot is not dissimilar to the PNA

This plot is not dissimilar to the PNA

 

While I agree focusing on the Pacific is key as in most years it is the main driver, I am not so sure that just the general overall SST look through the whole basin is where I would begin or even base my whole outlook on. There is a good reason that people focus first and foremost on the ENSO domain. Now while the ONI values are somewhat similar between these years,  notice the SST distribution along the equator through the ENSO region and how they differ. With these differing looks we are seeing different forcings that are affecting the Walker Cell strength and location within the Pacific (see modoki nino as an example). This Walker cell setup is probably the key thing that should be focused on. So if you want to focus on SST distribution I would probably start there and then work out to the secondary areas (warm blob, IOD, etc...) of importance and then use the general overall SST's as a fine tuning. Now considering that we are discussing the winter weather for the Atlantic I am not so sure I would also totally ignore the other secondary drivers downstream. Though not often, we do see on a occasion where they do trump the PAC (such as a strong -NAO). Even when they don't override the PAC they do add nuances to the pattern through our region that can make or break us as most years we are living on the edge. 

Ssts over the equatorial Pacific were my baseline with a general weakly cool east tropical Pacific and warmer from west to central Pacific basin leading into the cold season (where we are now).  I agree the sample size is an issue, but I couldn't find any other years that showed such a tropical look along with the moderate warm blob look.

Share this post


Link to post
Share on other sites

A little more on the IOD.

I agree it is an important driver but some years with a very positive IOD do not seem to fit this year. 

Figuring out the role of the +IOD as a driver this winter will be critical. I know HM is following this. 

May help with favorable MJO phases and possibly with the placement of tropical forcing as well.    However,  not 100 % sure about those possible relationships. 

 

 

Share this post


Link to post
Share on other sites

In regards to this  post by Ben  I don't see the logic. I see persistence of the last 8 winter with an averaged + NAO , but to use that as reasoning/support  that this winter will have a another +NAO  , eh, not so sure. 

I like Dave's response  as a counter .

 

 

From Dave 

 

 

 

  • Like 1

Share this post


Link to post
Share on other sites

I would exercise caution about using summertime NAO as a means to predict the wintertime NAO. I looked back at the NAO index from 1989-2018 and of those 30 years, just 13 had a pos/pos or neg/neg relationship, which is good for an r-value of just 0.09. Aka no correlation. 

Additionally, there have been 9 summers prior to 2019 (1993, 1998, 2000, 2008, 2009, 2011, 2012, 2015, 2016) where the NAO index has averaged less than -1. Among those years, a -NAO in DJF was observed in only 2 of the subsequent winters. 

  • Like 2
  • Thanks 2

Share this post


Link to post
Share on other sites
45 minutes ago, Winter Wizard said:

I would exercise caution about using summertime NAO as a means to predict the wintertime NAO. I looked back at the NAO index from 1989-2018 and of those 30 years, just 13 had a pos/pos or neg/neg relationship, which is good for an r-value of just 0.09. Aka no correlation. 

Additionally, there have been 9 summers prior to 2019 (1993, 1998, 2000, 2008, 2009, 2011, 2012, 2015, 2016) where the NAO index has averaged less than -1. Among those years, a -NAO in DJF was observed in only 2 of the subsequent winters. 

That makes sense,  I believe I mentioned in previous posts that the summer -NAO average means little for the upcoming winter.

However,  to say the next winter will have a positive averaged NAO just because the last 8 winters did is not a sound enough reason  for me.

Thanks for your post. 

Share this post


Link to post
Share on other sites
1 hour ago, frd said:

That makes sense,  I believe I mentioned in previous posts that the summer -NAO average means little for the upcoming winter.

However,  to say the next winter will have a positive averaged NAO just because the last 8 winters did is not a sound enough reason  for me.

Thanks for your post. 

If all else fails, persistence forecasting is usually the way to go, though it's nearly impossible to predict the NAO this far out with any kind of skill. 

  • Like 1

Share this post


Link to post
Share on other sites
23 minutes ago, Winter Wizard said:

If all else fails, persistence forecasting is usually the way to go, though it's nearly impossible to predict the NAO this far out with any kind of skill. 

Such as saying climo temps and snowfall for the winter ahead, thinking of going climo and then adding some additional warmth is a safe bet.  Extreme snowfall forecasts are so hard to come by lately. 

However, so tempting to find the weather holy grail and being the only met to forecast out of consensus cold and snow. A fine line between hype and reality.     

Share this post


Link to post
Share on other sites

Since the NAO is being discussed in here, I thought I would share something I found with you folks. Just throwing this out there for discussion. UCL (University College of London) has a group that has made a prediction for the NAO for this upcoming winter season. Namely January and February. If it actually happens, who knows but I thought I would share it. 

 

"Our  deterministic  (single  most  likely)  forecast  for  the  2020  JF  NAO  is  a  value  of  -0.86  or  -0.85  in standardised  units.  This  would  rank  the  2020  JF  NAO  as  the  most  negative  JF  NAO  since  JF  2010  and the  thirteenth most  negative  JF  NAO  since  1953."

 

Their data and methods can be found in PDF form here: 

http://discovery.ucl.ac.uk/10080518/1/Saunders_Lea and Smallwood (2019).pdf

  • Like 3
  • Thanks 2

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.