Fall Speculation About Winter 20-21

[bluewave]

Winter 20-21 discussion for NYC Metro.

[uncle W]

yesterday jb back tracked on his call for a mild snowless winter...he quoted a similarity with the 2010 arctic oscillation...

[SnoSki14]

So there's some hope winter won't be dead this year?

[uncle W]

QBO is similar to 2010 and 1966 but will it continue...Both winters featured a qbo of at least +10 throughout the winter...

[uncle W]

NYC snowfall in la nina years...(ONI) ...13 years with at least 20" of snowfall...11 years with less than 20" of snowfall...

60"+ winters...two...2010-11...1995-96...

40-49.9"..........two...2005-06...2017-18...

30-39.9"........three...2016-17...2000-01...1955-56...

20-29.9"...........six....2008-09...1984-85...1983-84...1973-74...1971-72...1964-65...

15-19.9"........three...1999-00...1975-76...1970-71...

10-14.9"...........six.....2007-08...1998-99...1974-75...1954-55...1950-51...1949-50

00'09.9"...........two....2011-12...1988-89...

[bluewave]

On 10/6/2020 at 3:50 PM, uncle W said:

NYC snowfall in la nina years...(ONI) ...13 years with at least 20" of snowfall...11 years with less than 20" of snowfall...

60"+ winters...two...2010-11...1995-96...

40-49.9"..........two...2005-06...2017-18...

30-39.9"........three...2016-17...2000-01...1955-56...

20-29.9"...........six....2008-09...1984-85...1983-84...1973-74...1971-72...1964-65...

15-19.9"........three...1999-00...1975-76...1970-71...

10-14.9"...........six.....2007-08...1998-99...1974-75...1954-55...1950-51...1949-50

00'09.9"...........two....2011-12...1988-89...

Main La Niña theme since 2000 has been a dominant SE Ridge. The years with over 20” in NYC had Alaska and Greenland blocking episodes mixed with the SE Ridge. 16-17 was a great example of a few well timed blocks in a warm SE Ridge pattern producing respectable seasonal snowfall totals. 
 

[LibertyBell]

Chris, remember we talked about how a cold October and mild November used to be a pretty good indicator of a snowy winter?  That lasted until 1996 lol.

 

[Allsnow]

 

[Allsnow]

On 10/6/2020 at 4:42 PM, bluewave said:

We'll see if the MJO lingering in phase 4-5 this October means NYC has a chance of going over 20 inches this coming season. But we never know for sure if these fall indicators will work out. Main La Niña theme since 2000 has been a dominant SE Ridge. The years with over 20” in NYC had Alaska and Greenland blocking episodes mixed with the SE Ridge. 16-17 was a great example of a few well timed blocks in a warm SE Ridge pattern producing respectable seasonal snowfall totals. 
 

Looks like we will attempt to get into phase 7 at the end of October 

[Allsnow]

55 minutes ago, bluewave said:

The closest looking October MJO match so far seems to be 2017. But you never know if that means the snowfall relationship will work out this year. The JMA just joined all the other seasonal guidance with a warm and potentially below normal snowfall winter. While the seasonal models often have low skill, warm and less snowy would match the last 2 Niña-like winters. On the other hand, we haven’t had 3 consecutive below normal snowfall seasons here since the late 90s. So it will be interesting to see how the coming season turns out. 

 

Yeah, 17-18 was a classic Niña winter. Cold December to early January, then the pattern flipped to warmth until a SSW brought blocking for March. 

[uncle W]

NYC ...

la nina winters...weak negative winters...

winter..............DJF ONI...Dec-Mar AO...A.T....min....30 day cold...snowfall...biggest snowfalls...ranked by the coldest to warmest Dec-Feb period...

1962-63..............-0.4.............-1.255........30.0....-2..........25.9..........16.3"..........4.2"

1967-68..............-0.7.............-0.342........31.3....-1..........25.1..........19.5"..........6.6"

1970-71..............-1.3.............-0.644........32.1.....4..........24.2..........15.5"..........6.4"

1995-96..............-0.9.............-1.162........32.3.....5..........27.7..........75.6"..........20.2" 10.7" 7.9" 7.5" 4.6" 4.6" 4.1"

1955-56..............-0.9.............-0.512........32.7.....5..........27.6..........33.5"..........11.6" 6.5" 4.2"

2010-11..............-1.3.............-0.329........32.7.....6..........28.1..........61.9"..........20.0" 19.0" 9.1" 5.0"

2013-14..............-0.5............+0.439........33.0.....4..........28.5..........57.4"..........12.5"...11.5"...8.0"...6.4"...5.0"...4.0"

1964-65..............-0.5.............-1.070........33.3.....9..........28.0..........24.4"............6.3".....4.6"

1985-86..............-0.4.............-0.872........33.4.....8..........31.0..........13.0"............4.5"....4.5"

2000-01..............-0.7.............-1.406........33.5...14..........29.9..........35.0"..........12.0"....6.0"....5.7"

 

1954-55..............-0.6.............-0.930........34.0.....0..........28.6..........11.5"............3.9"

1966-67..............-0.4............+0.293........34.1.....4..........28.6..........51.5"..........12.5".....9.8"...7.1"

2008-09..............-0.7............+0.224........34.2.....6..........27.9..........27.6"............8.3".....4.5"....4.3"

1975-76..............-1.5............+0.892........34.4....-1..........27.1..........17.3"............4.2" 4.0"

1971-72..............-0.7............+0.164........35.1.....5..........28.6..........22.9"............5.7".....5.2"

1983-84..............-0.5.............-0.400........35.2.....4..........26.1..........25.4"............6.9".....5.1"....4.6"

1973-74..............-1.7.............-0.296........35.5.....6..........32.3..........23.5"............6.0" 4.3"

1950-51..............-0.8.............-1.084........35.9.....9..........33.0..........11.6"............3.0"

1988-89..............-1.6............+2.399........35.9.....5..........32.4............8.1"............5.0"

1999-00..............-1.6............+0.735........36.2.....3..........26.2..........16.3"............5.5"

 

2017-18..............-0.9.............-0.291........36.2.....5..........28.0..........40.9"............4.6" 9.8" 4.4" 8.4" 5.5"

2007-08..............-1.4............+0.531........36.4...10..........35.7..........11.9"............6.0"

1984-85..............-0.9.............-1.062........36.4....-2..........27.5..........24.1"............5.7" 4.8" 4.3" 4.1"

2012-13..............-0.4.............-1.838........36.9...11..........31.5..........26.1"...........11.4"....4.7"

2005-06..............-0.7.............-1.008........37.3...14..........33.5..........40.0"...........26.9"....5.8"

1949-50..............-1.4............+0.190........37.5.....6..........31.6..........13.8".............3.8"

1974-75..............-0.5............+0.624........37.5...15..........33.0..........13.1".............7.8"

1996-97..............-0.5............+0.201........37.8.....4..........31.7..........10.0".............3.5"

1998-99..............-1.4............+0.113........38.7.....9..........31.3..........12.7".............4.5"

2016-17..............-0.4............+1.108........39.3...14..........35.5..........30.2".............9.4"....7.6"....5.1"

2011-12..............-0.7............+0.750........40.5...13..........37.0............7.4".............4.2"

[jm1220]

We need a snowy December in a Nina here or it’ll be a bust. The SE ridge inevitably comes back in Jan into Feb. Even 10-11 quieted down after the late Jan snow event. In 17-18 we lucked out with the March events but we can’t count on that for sure. The background state becoming more and more Nina like over the last decade (with a couple of exceptions) was destined to bite us eventually. There are some ways we can luck out but we also need help from the NAO to keep the ridge at bay. If we don’t have that on our side either it’ll be another lousy winter. I’m not too excited for this winter but even normal snow is a solid improvement. 

[uncle W]

la nina winters in NYC...

year.......Dec snow.......total snow...

2017........7.7"....................40.9"

2016........3.2"....................30.2"

2011...........0........................7.4"

2010.......20.1"....................61.9"

2008.........6.0"....................27.6"

2005.........9.7"....................40.0"

2000.......13.4"....................35.0"

1999..........T........................16.3"

1998.........2.0".....................12.7"

1996...........T........................10.0"

1995........11.5"....................75.6"

1988..........0.3".......................8.1"

1984..........5.6"....................24.1"

1983..........1.8"....................25.4"

1975..........2.3"....................17.3"

1974..........0.1"....................13.1"

1973..........2.8"....................23.1"

1971............T.......................22.9"

1970..........2.4"....................15.5"

1964..........3.1"....................24.4"

 

[TriPol]

Every 15 years or so, starting with 1995, we get a nice La Nina winter! We're due!

[raindancewx]

Your snowfall in NYC is pretty tied to the ACE Index in La Nina years. The MJO has different wavelengths and magnitudes each year, and a lot of La Ninas won't have any substantial MJO waves.

Below 150 ACE in a La Nina, NYC is 2 for 17 at topping 30" of snow, which is what I'd consider a "good" season for NYC, instead of just near average, in the 1931-2019 period. The 2016-17 La Nina was arguably a Neutral and and had 146 ACE, so it hardly counts (30.2"), and 1938-39 isn't really a likely outcome for the winter. At the current 123 ACE, you'd expect 25 inches of snow or so, based on the 10 closest ACE years. I do expect the ACE to go up a bit more, but probably not above 150. The 10 La Ninas above 150 ACE since 1931, feature five snow years above 40" in NYC, compared to 0/17 for the under 150 years..

 

[dmillz25]

8 hours ago, raindancewx said:

Your snowfall in NYC is pretty tied to the ACE Index in La Nina years. The MJO has different wavelengths and magnitudes each year, and a lot of La Ninas won't have any substantial MJO waves.

Below 150 ACE in a La Nina, NYC is 2 for 17 at topping 30" of snow, which is what I'd consider a "good" season for NYC, instead of just near average, in the 1931-2019 period. The 2016-17 La Nina was arguably a Neutral and and had 146 ACE, so it hardly counts (30.2"), and 1938-39 isn't really a likely outcome for the winter. At the current 123 ACE, you'd expect 25 inches of snow or so, based on the 10 closest ACE years. I do expect the ACE to go up a bit more, but probably not above 150. The 10 La Ninas above 150 ACE since 1931, feature five snow years above 40" in NYC, compared to 0/17 for the under 150 years..

 

Alot better than the 4.8” we got last year

[LibertyBell]

13 hours ago, jm1220 said:

We need a snowy December in a Nina here or it’ll be a bust. The SE ridge inevitably comes back in Jan into Feb. Even 10-11 quieted down after the late Jan snow event. In 17-18 we lucked out with the March events but we can’t count on that for sure. The background state becoming more and more Nina like over the last decade (with a couple of exceptions) was destined to bite us eventually. There are some ways we can luck out but we also need help from the NAO to keep the ridge at bay. If we don’t have that on our side either it’ll be another lousy winter. I’m not too excited for this winter but even normal snow is a solid improvement. 

My favorite was actually the snowstorm in April!  That was a historic cold pattern in March and April that year.

 

[uncle W]

12 hours ago, uncle W said:

la nina winters in NYC...

year.......Dec snow.......total snow...

2017........7.7"....................40.9"

2016........3.2"....................30.2"

2011...........0........................7.4"

2010.......20.1"....................61.9"

2008.........6.0"....................27.6"

2005.........9.7"....................40.0"

2000.......13.4"....................35.0"

1999..........T........................16.3"

1998.........2.0".....................12.7"

1996...........T........................10.0"

1995........11.5"....................75.6"

1988..........0.3".......................8.1"

1984..........5.6"....................24.1"

1983..........1.8"....................25.4"

1975..........2.3"....................17.3"

1974..........0.1"....................13.1"

1973..........2.8"....................23.1"

1971............T.......................22.9"

1970..........2.4"....................15.5"

1964..........3.1"....................24.4"

 

its hard to get a snowstorm that's 4" or more in December during a la nina year...only seven years had one since 1950...mostly recent years...

2017......4.6"

2010....20.0"

2008......4.0"

2005......5.8"

2000....12.0"

1995......7.7"

1984......4.8"

 

[FPizz]

Just now, uncle W said:

its hard to get a snowstorm that's 4" or more in December during a la nina year...only seven years had one since 1950...mostly recent years...

2017......4.6"

2010....20.0"

2008......4.0"

2005......5.8"

2000....12.0"

1995......7.7"

1984......4.8"

 

Maybe it is becoming easier since 5 happened in the last 20 years

[uncle W]

1 minute ago, FPizz said:

Maybe it is becoming easier since 5 happened in the last 20 years

none from 1950 to 1984...I dont have enso numbers before 1950 handy so I cant say how la nina years passed without a 4" snowstorm in NYC...maybe because we are still in a wetter regime...

[frd]

On 10/13/2020 at 3:27 PM, bluewave said:

Yeah, we usually get a pretty good idea about La Niña seasonal snowfall pretty early on. Every La Niña or La Niña-like December with over 3” of snow in NYC since 2000 went on to normal to above normal seasonal snowfall. But the under 3” Decembers like the last 2 years finished the season with below average snowfall.

La Niña and Niña-like winters bolded

Do you know if this tendency in a Nina carries to lower latitudes as well, such as the Northern Mid Atlantic ?

I have always felt, and observed, during the past 40 years a snowy December exceeding 6 inches of snowfall in my area goes on to produce above normal snowfall in the ensuing winter ( in a Nino year ) . So far that indicator has done very well.  

 

 

[EasternLI]

The west pacific warm pool is of some interest this year IMO. It's something that I will certainly be paying attention to in looking at the sst trends in that area in the month ahead. This relates to the discussion of the PMM in the discussion thread. 

 

There's potentially some optimistic outcomes that could (or could not lol) stem from this as it relates to the winter ahead. Some recent research has shown that forcing in this area can actually drive an Aleutian low +PNA pattern during winter. Which in turn can act to cause a weak SPV. It should be interesting to monitor this area moving forward. 

 

Nonlinear response of Northern Hemisphere stratospheric polar vortex to the Indo–Pacific warm pool (IPWP) Niño https://www.nature.com/articles/s41598-019-49449-7

During boreal winter, anomalous SST warming associated with IPWP Niño can excite NH extratropical teleconnections that project onto the positive phase of the Pacific–North America (PNA) pattern in mid–high latitudes, intensifying the upward propagation of planetary waves into the stratosphere and, in turn, warming and weakening the NH stratospheric vortex41. Note that the wave pattern excited by IPWP Niño is located further west than the PNA pattern, a fact that may be related to the different wave source locations from that of ENSO.

[dmillz25]

https://easternmassweather.blogspot.com/2020/11/winter-outlook-2020-2021-mixed-type-la.html
@40/70 Benchmark write up on the upcoming winter. Excellent read

[40/70 Benchmark]

I should have posted that in here, too.

Thanks.

[jm1220]

19 minutes ago, 40/70 Benchmark said:

I should have posted that in here, too.

Thanks.

Excellently written. I obviously hope it’s wrong and it would be a winter of pure misery here but hard to argue. 

[EasternLI]

This is what the GEFS and EPS is showing for VP200. The new EPS weaklies today continues this look right into December. Research says that Indian ocean convection will drive a strong polar vortex. Last year is a great example of that occurring. I didn't give that enough respect. So expecting a ++AO La Nina as of now unless something changes here and quickly. 

[snowman19]

12 hours ago, EasternLI said:

This is what the GEFS and EPS is showing for VP200. The new EPS weaklies today continues this look right into December. Research says that Indian ocean convection will drive a strong polar vortex. Last year is a great example of that occurring. I didn't give that enough respect. So expecting a ++AO La Nina as of now unless something changes here and quickly. 

Think another issue is the massive amount of wildfire smoke that got pumped into the stratosphere, that would also promote +AO

[bluewave]

15 hours ago, EasternLI said:

This is what the GEFS and EPS is showing for VP200. The new EPS weaklies today continues this look right into December. Research says that Indian ocean convection will drive a strong polar vortex. Last year is a great example of that occurring. I didn't give that enough respect. So expecting a ++AO La Nina as of now unless something changes here and quickly. 

 

Great post. The quick reversal from -AO in October to +AO in November is something that we normally see during an El Niño. This may be related to lingering neutral to positive IOD which is also more Niño-like. The IO standing wave the models have for November was implicated in the very strong PV and +NAO +AO last winter. The current +PMM with near record SST warmth north of such a strong La Niña cold tongue is also a first for a La Niña.  A very warm November has also been associated with El Niño’s in the past. Several times this warm November during an El Niño carried over into December. So such an occurrence this year would be different than the typical front loaded La Niña winter progression. There have also been several very warm La Niña Novembers followed  by warm Decembers. On the other hand, a warmer PMM was present for our most recent La Niña warm November in 2016. That was a near record warm winter. But it may have been the +PMM allowing occasional poleward extensions of the North Pacific Ridge into Alaska. Those were also accompanied by short -NAO -AO episodes for respectable seasonal snowfall despite the record warmth. There are many factors this year which could interact. We may just have to wait and see how things look in another month or so. But even beyond  the specific ENSO conditions and interactions, we have just seen the warmest 5 winter stretch on record. 

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

 

[40/70 Benchmark]

4 hours ago, bluewave said:

Great post. The quick reversal from -AO in October to +AO in November is something that we normally see during an El Niño. This may be related to lingering neutral to positive IOD which is also more Niño-like. The IO standing wave the models have for November was implicated in the very strong PV and +NAO +AO last winter. The current +PMM with near record SST warmth north of such a strong La Niña cold tongue is also a first for a La Niña.  A very warm November has also been associated with El Niño’s in the past. Several times this warm November during an El Niño carried over into December. So such an occurrence this year would be different than the typical front loaded La Niña winter progression. There have also been several very warm La Niña Novembers followed  by warm Decembers. On the other hand, a warmer PMM was present for our most recent La Niña warm November in 2016. That was a near record warm winter. But it may have been the +PMM allowing occasional poleward extensions of the North Pacific Ridge into Alaska. Those were also accompanied by short -NAO -AO episodes for respectable seasonal snowfall despite the record warmth. There are many factors this year which could interact. We may just have to wait and see how things look in another month or so. But even beyond  the specific ENSO conditions and interactions, we have just seen the warmest 5 winter stretch on record. 

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

 

I don't know about literal "record" warmth for the season, but the rest of that is essentially my winter forecast. I think I would favor February for actual record warmth.

[uncle W]

4 hours ago, bluewave said:

Great post. The quick reversal from -AO in October to +AO in November is something that we normally see during an El Niño. This may be related to lingering neutral to positive IOD which is also more Niño-like. The IO standing wave the models have for November was implicated in the very strong PV and +NAO +AO last winter. The current +PMM with near record SST warmth north of such a strong La Niña cold tongue is also a first for a La Niña.  A very warm November has also been associated with El Niño’s in the past. Several times this warm November during an El Niño carried over into December. So such an occurrence this year would be different than the typical front loaded La Niña winter progression. There have also been several very warm La Niña Novembers followed  by warm Decembers. On the other hand, a warmer PMM was present for our most recent La Niña warm November in 2016. That was a near record warm winter. But it may have been the +PMM allowing occasional poleward extensions of the North Pacific Ridge into Alaska. Those were also accompanied by short -NAO -AO episodes for respectable seasonal snowfall despite the record warmth. There are many factors this year which could interact. We may just have to wait and see how things look in another month or so. But even beyond  the specific ENSO conditions and interactions, we have just seen the warmest 5 winter stretch on record. 

Predictability of European winter 2019/20: Indian Ocean dipole impacts on the NAO

https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005

 

I don't like what's happening with the ao this month...It makes me think the first half of winter sucks if you like snow...there can always be a rogue storm but that's grasping for staws...maybe things will get better by the end of January...a positive ao does't mean it will be mild all the time...it can even be cld like in 1988 and 1975...