Winter 2020-21 Discussion

[frd]

35 minutes ago, CAPE said:

Go back and read the previous few pages ITT. This has been discussed at length.

Also I am not sure anyone is 'canceling' winter. Well maybe Ji has, but he doesn't count.

Seems that Greenland ice melt effects ( has altered )  the Greenland ocean circulation/tripole that is used to forecast the winter's ensuing  dominate NAO  phase. Just started to research this and also read a few intriguing posts by HM. 

Some state the summer ice melt was not as bad in Greenland, but according to HM is still was not great when you target  on his on his focus which is  repairing the Greenland ocean circulation/tripole. As HM states,  the ice melts throws a monkey wrench in the NAO forecasts of the upcoming winter.  

 

HM states it is better to look at the Spring's tripole for an indication of the ensuing winter's NAO versus the tropical season. Caveats apply though, in regards to Greenland ice melt and AGW.   Some interesting things to consider here.   

 

 

 

 

[MountainGeek]

Here's a pretty cool ENSO - snowfall chart from Josh Timlin; this clearly illustrates many of the ongoing discussion points, especially in terms of setting general expectations for the upcoming winter:

https://www.joshtimlin.com/enso-charts-winter

[snowman19]

2 hours ago, frd said:

Seems that Greenland ice melt effects ( has altered )  the Greenland ocean circulation/tripole that is used to forecast the winter's ensuing  dominate NAO  phase. Just started to research this and also read a few intriguing posts by HM. 

Some state the summer ice melt was not as bad in Greenland, but according to HM is still was not great when you target  on his on his focus which is  repairing the Greenland ocean circulation/tripole. As HM states,  the ice melts throws a monkey wrench in the NAO forecasts of the upcoming winter.  

 

HM states it is better to look at the Spring's tripole for an indication of the ensuing winter's NAO versus the tropical season. Caveats apply though, in regards to Greenland ice melt and AGW.   Some interesting things to consider here.   

 

 

 

 

The Greenland ice melt is extremely disturbing. Not as bad as 2012 but it’s still at record levels. If there were any more doubts about AGW having a major effect on our climate and global circulations, this is a very good example. Even HM is clueless as to which way the NAO is going this winter. Should be interesting to see what Isotherm says

[CAPE]

34 minutes ago, snowman19 said:

The Greenland ice melt is extremely disturbing. Not as bad as 2012 but it’s still at record levels. If there were any more doubts about AGW having a major effect on our climate and global circulations, this is a very good example. Even HM is clueless as to which way the NAO is going this winter. Should be interesting to see what Isotherm says

The NAO is notoriously unpredictable at long leads. One thing we have to go on is persistence. The NAO has been predominately positive during winter for many years.

[snowman19]

4 minutes ago, CAPE said:

The NAO is notoriously unpredictable at long leads. One thing we have to go on is persistence. The NAO has been predominately positive during winter for many years.

I mentioned it before, but I think all this record arctic sea ice melt is also contributing to the persistently +AO and +NAO winters we have been seeing. IMO it’s not a coincidence and it’s created a positive feedback loop 

[frd]

 

Pondering the Nina correlation to the ensuing winter's  NAO and IOD, well.................   

 

 

[40/70 Benchmark]

13 minutes ago, 40/70 Benchmark said:

Last update from me until go-time Novie 11.

https://easternmassweather.blogspot.com/2020/10/mixed-signals-regarding-enso-for-winter.html

 

[Scraff]

30 minutes ago, 40/70 Benchmark said:

 

The DMV winters for your analogs of 1970-71 and 1999-2000 would be acceptable. 2007-2008 not so much, though would still be better than last winters sadness. Haha. 

[40/70 Benchmark]

Just now, Scraff said:

The DMV winters for your analogs of 1970-71 and 1999-2000 would be acceptable. 2007-2008 not so much, though would still be better than last winters sadness. Haha. 

That is not my complete composite....just the three best ENSO matches by a combo of structure and intensity.

[frd]

23 minutes ago, 40/70 Benchmark said:

That is not my complete composite....just the three best ENSO matches by a combo of structure and intensity.

Interesting update. 

Do you feel those analogs you mention are still useful in our present climate regime?   

You must feel they have have some merit of course,  as you  stated they are the " best ENSO match by a combo of structure and intensity,"  but wondering whether you could comment further.   

 

[40/70 Benchmark]

12 minutes ago, frd said:

Interesting update. 

Do you feel those analogs you mention are still useful in our present climate regime?   

You must feel they have have some merit of course,  as you  stated they are the " best ENSO match by a combo of structure and intensity,"  but wondering whether you could comment further.   

 

Its pretty self explanatory......IMHO those are the best matches using a combo of ENSO intensity and distribution of warmest SST anomalies. I mean, we are mainly referencing "anomalies" when speaking of sensible weather, so I don't see why the end result should be much different. I def. would shy away from using very potent la nina as analog seasons, given that ENSO may not be as a pervasive driver due to AGW.

[psuhoffman]

2 hours ago, frd said:

 

Pondering the Nina correlation to the ensuing winter's  NAO and IOD, well.................   

 

 

That’s what I found. Nina’s for us (excluding 1996) range from totally awful or just mediocre and the other factors that determine that differentiation (EPO/NAO) have very little correlation or reliable predictive tells. We know it’s likely to be a NS dominant winter so big snows are unlikely. But we could have a colder close to normal winter or a warm clone of last winter and it’s very difficult to predict which variant of Nina is coming ahead of time.  This year even more so because of conflicting signals. 

[psuhoffman]

9 hours ago, CAPE said:

It will snow this winter. Projected mean patterns are just that. We normally get a few shots each winter. Last winter was an o-fer for most, and while it could happen again this winter, it probably won't.

Nina winters don't often produce above avg snow, and can be super frustrating with the typical NS dominant flow/late developing coastals. I will say this again- the last 2 Ninas produced slightly below median, and slightly above avg snowfall here, respectively. Both produced big snowstorms(one was a blizzard) for the immediate coastal plain, with no blocking. Clearly better outcomes than the so called Nino and warm neutral of the past 2 winters for my yard.

And yes, while DC-BWI and west missed both of those Nina events, it wouldn't have taken much for better outcomes in those areas.

Ofc this is a imby business, so I don't care. 

One of those was a weak Nina (2018) and the other was actually cold neutral (2017). It was looking like a Nina in fall but ended up neutral but since it was kinda a Nina ish pattern and not so great winter most just think of it as a Nina.  But there are lots of examples of weak cold enso seasons including some decent periods of cold and snow absent blocking.  In a weak Nina the pac ridge can fluctuate and weaken enough at times. Unfortunately that isn’t true of strong cold enso. So if we’re heading for a strong Nina, and everything indicates such, we probably will need blocking or we’re unlikely to get much luck like those years you reference. 
 

That doesn’t mean I am canceling winter.  Persistence is hard to ignore but the NAO can flip on a dime. We could get blocking help this year.  But if we get a positive NAO all winter like last year...it’s probably going to be very similar. 
 

lastly, when I say very similar it doesn’t mean we all get the exact same results as last year.  2 points.  First let’s say DC lucks it’s way to a 2” clipper in Dec and then some fluke lucky timed wave like last January is 20 miles further south and there get a 3” wet snow event in January. And that’s it. The rest of winter is 50+ degrees. DC gets 5” which puts it more in line with its common crap winters. But it wasn’t significantly different from last year. Just slightly luckier. And I have my doubts the people that get 5” vs 1” are really going to look back when it’s over and feel good about it!   Lastly I am probably even more pessimistic because I didn’t get 1” I actually lucked my way to about 16” up here.  And I got 7.5” over 2 days in January. And I knew that was likely “it” and so I enjoyed the crap out of it!  But when I pull the analogs to strong Nina with a +NAO more are actually WORSE for me than last year!!!  2 of them are literally the worst 2 winters here in over 125 years of records and another is the 4th worst!!!  Only 1 in the set is better. So actually statistically if we see a strong Nina with a + NAO I am likely to get less snow than I did last winter. As you said it’s and IMBY thing. 

[psuhoffman]

3 hours ago, 40/70 Benchmark said:

 

Excellent write up. Only problem in application of those analogs is how drastically different they were for our area. 1971 and 2000 both featured at least one period of blocking which allowed us to cash in on a respectable snowy period. 2008 did not and so was a pretty awful non winter wall to wall. I think the general pattern is known but whether we can salvage some snow here in the mid Atlantic depends on how much if any blocking help and I see no reliable tells to tip that hat. Your area can work without it but Baltimore has never had a warning  (5”) event during a moderate or strong Nina without blocking. Furthermore when I did a pattern analysis of every warning event back to 1948 Baltimore never even lucked into a warning snow in a Nina like central pac ridge pattern in a non Nina year without blocking.  So imo for our area as the high latitudes go so goes our snow chances and I’ve yet to identify a strong indicator other than pure persistence.  

[40/70 Benchmark]

28 minutes ago, psuhoffman said:

Excellent write up. Only problem in application of those analogs is how drastically different they were for our area. 1971 and 2000 both featured at least one period of blocking which allowed us to cash in on a respectable snowy period. 2008 did not and so was a pretty awful non winter wall to wall. I think the general pattern is known but whether we can salvage some snow here in the mid Atlantic depends on how much if any blocking help and I see no reliable tells to tip that hat. Your area can work without it but Baltimore has never had a warning  (5”) event during a moderate or strong Nina without blocking. Furthermore when I did a pattern analysis of every warning event back to 1948 Baltimore never even lucked into a warning snow in a Nina like central pac ridge pattern in a non Nina year without blocking.  So imo for our area as the high latitudes go so goes our snow chances and I’ve yet to identify a strong indicator other than pure persistence.  

Its not a problem if you apply them correctly, which I will attempt to do.

Not all about blocking, though....you guys need it to couple with a PNA spike, usually. SNE ca get away with one or the other.

[frd]

As Anthony mentions,  the weekly value does not define the strength of the Nina.   However, it has joined a few others in the strong group, in week 42. 

 

[frd]

Speaking of analogs,  take from this what you want.  Both threads below have very interesting takes on climatology, analogs and SSTs . 1942 did happen during WWII. 

 

 

[psuhoffman]

1 hour ago, frd said:

Speaking of analogs,  take from this what you want.  Both threads below have very interesting takes on climatology, analogs and SSTs . 1942 did happen during WWII. 

 

 

Yea it’s hard to find good global sst matches anymore. 1942/3 is intriguing as it was one of the best Nina outcomes we’ve had. I would be VERY happy if it went down that way. But it’s dangerous using analogs from such a different time period. 

[frd]

1 hour ago, psuhoffman said:

But it’s dangerous using analogs from such a different time period

So true. Only with climate adjustments and weighting can you even begin to consider older analogs . 

[JakkelWx]

There's no escaping the disaster that will be the 2020-21 winter.

[Maestrobjwa]

7 minutes ago, JakkelWx said:

There's no escaping the disaster that will be the 2020-21 winter.

Only magical escape routes...this being 2020 and the last "history" trend that hasn't officially failed yet in the solar minimum  Both of those things don't deliver then yeah...lol

But it's funny...with stuff being so whacky since 2016, with the rug being pulled out with bad surprises of things not working the way they looked to be in the pre-winter forecasting...you wonder why we couldn't get a good surprise for a change...with stuff not work the way it appears to be right now, lol 

[Snowy Hibbo]

https://longrangesnowcenter.net/2020/10/20/october-preliminary-2020-21-winter-outlook/

An interesting splash of factors, for the Eastern US, a few shifts (particularly on ENSO) from last time I dropped in:

1. A basinwide moderate (possibly strong) La Nina this winter. 
2. A positive QBO 
3. Solar Minimum 
4. Atlantic SSTs favourable for a +NAO 
5. North Pacific SSTs favourable for a Aleutian Ridge. 
6. Average growth of Stratospheric Polar Vortex into winter, potential for SSWs later. 
7. Phase 3-6 MJO centred tropical base state 
8. Low sea ice in Barents-Kara Sea. 
9. Average snow coverage in Siberia. 

Looking pretty average in terms of snowfall for the Mid Atlantic IMO.

[psuhoffman]

1 hour ago, Snowy Hibbo said:

https://longrangesnowcenter.net/2020/10/20/october-preliminary-2020-21-winter-outlook/

An interesting splash of factors, for the Eastern US, a few shifts (particularly on ENSO) from last time I dropped in:

1. A basinwide moderate (possibly strong) La Nina this winter. 
2. A positive QBO 
3. Solar Minimum 
4. Atlantic SSTs favourable for a +NAO 
5. North Pacific SSTs favourable for a Aleutian Ridge. 
6. Average growth of Stratospheric Polar Vortex into winter, potential for SSWs later. 
7. Phase 3-6 MJO centred tropical base state 
8. Low sea ice in Barents-Kara Sea. 
9. Average snow coverage in Siberia. 

Looking pretty average in terms of snowfall for the Mid Atlantic IMO.

Almost every one of those factors is opposite what we want. That’s “average”?  I guess lately...

[yoda]

Looks like parts of Iowa (DVN CWA) got a surprise snowfall yesterday

https://www.weather.gov/dvn/summary_101920

https://www.weather.gov/source/crh/snowmap.html?zoom=8&lat=41.65&lon=-93.34&hr=48

[snowman19]

8 hours ago, Snowy Hibbo said:

https://longrangesnowcenter.net/2020/10/20/october-preliminary-2020-21-winter-outlook/

An interesting splash of factors, for the Eastern US, a few shifts (particularly on ENSO) from last time I dropped in:

1. A basinwide moderate (possibly strong) La Nina this winter. 
2. A positive QBO 
3. Solar Minimum 
4. Atlantic SSTs favourable for a +NAO 
5. North Pacific SSTs favourable for a Aleutian Ridge. 
6. Average growth of Stratospheric Polar Vortex into winter, potential for SSWs later. 
7. Phase 3-6 MJO centred tropical base state 
8. Low sea ice in Barents-Kara Sea. 
9. Average snow coverage in Siberia. 

Looking pretty average in terms of snowfall for the Mid Atlantic IMO.

Nice write up

[frd]

1 hour ago, snowman19 said:

Nice write up

Many of those factors we have heard already, especially the possibility regarding the poleward Aleutian ridge. 

Wondering the effect of less sea ice, however, my thoughts focus on rapid snow cover up North along with a November

enhanced - EPO /  +PNA  later November. Snow is indeed expanding now in week 42 up North. 

How long the SST configuration lasts off the West Coast / North Pac  is up to debate. 

I am not so sure about a + NAO though, feel there may be a couple - episodes. Speculation on the Ural High connection. Keep an eye too on the Scandinavia–Greenland pattern . Although hard to predict beyond week 2.  More about that on the link below. 

https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3892

 

[frd]

 

Speaking of the Ural High and the Scandi - Greenland pattern, maybe showing up in a more significant fashion for the month of November. Worth following, as the implications are significant, both short-term and long-term. 

 

 

[frd]

 

A look at the latest CFSv2 and the GEFS 35 day forecasts we see overall the early season vortex still close to the seasonal ERA5 mean. The CFSv2 actually a little below the mean,  with the GEFS slightly above the ERA5 mean. 

 

While the 35 day GEFS tracks the PV slightly above the seasonal ERA5 mean. 

 

 

[frd]

 

Interesting 

https://www.osti.gov/biblio/1613223

Ural Blocking as a Driver of Early-Winter Stratospheric Warmings

 

 

Abstract

This study explores the early-winter atmospheric response to Ural blocking anomalies in November, using a nudging technique to constrain the temperature and dynamics in a high-top atmospheric model. Persistent Ural blocking anomalies in November are associated with a warm Arctic/cold Siberia pattern and increased upward planetary waves entering the stratosphere, leading to a warming of the polar vortex. This stratospheric response then propagates in the troposphere, leading to increased occurrence of the negative North Atlantic Oscillation in December and January. In contrast, simulations with perturbed Barents-Kara sea ice and Siberian snow in November do not reproduce a significant atmospheric response. In simulations including a slab ocean, the Ural blocking induces Barents-Kara sea ice and Siberia snow anomalies that resemble composite analyses from observations. These results highlight Ural blocking variability in November as a robust driver of early-winter stratospheric warming while questioning causality between sea ice/snow and Ural blocking anomalies.

 

[CAPE]

29 minutes ago, frd said:

 

A look at the latest CFSv2 and the GEFS 35 day forecasts we see overall the early season vortex still close to the seasonal ERA5 mean. The CFSv2 actually a little below the mean,  with the GEFS slightly above the ERA5 mean. 

 

While the 35 day GEFS tracks the PV slightly above the seasonal ERA5 mean. 

 

Surprise!