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Winter 2020-21 Discussion


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5 hours ago, frd said:

 

Came across some posts ( research ),  maybe BAMMWX,  that alluded to a July and August -AO average correlates into a warm December in the East. 

Eh, whats new. 

 

 

ao.sprd2.gif

 

Never heard that correlation before. The thing you definitely don’t want with a Niña is +NAO/+AO due to the crap Pacific side Ninas normally produce, especially in combination with a -PDO. If you look back at the good Niña winters, they all had -NAO/-AO blocking. 08-09 had more -EPO which was a bit unusual for a Nina. 95-96 had a decent Pacific side due to the strong +PDO which was in place and highly unusual with an established Niña, also had strong AO/NAO blocking. I’m more interested to see how the QBO behaves this fall

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1 minute ago, CAPE said:

It will advertise plenty of -NAOs in the day 25+ range.

Is the NAO something you can definitively see on the model runs, or is it a kind of “looks close enough to a -NAO?”

Sure, it may look negative on the model, and never appear in the real world...

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Just now, Rhino16 said:

Is the NAO something you can definitively see on the model runs, or is it a kind of “looks close enough to a -NAO?”

Sure, it may look negative on the model, and never appear in the real world...

You can see it if it persists on the means. It is rarely modeled well in advance though. Also a transient ridge passing through the NAO domain really isn't  a NA block. The difference there is a thread the needle deal vs having persistence in forcing the storm track below us. 

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54 minutes ago, snowman19 said:

Never heard that correlation before. The thing you definitely don’t want with a Niña is +NAO/+AO due to the crap Pacific side Ninas normally produce, especially in combination with a -PDO. If you look back at the good Niña winters, they all had -NAO/-AO blocking. 08-09 had more -EPO which was a bit unusual for a Nina. 95-96 had a decent Pacific side due to the strong +PDO which was in place and highly unusual with an established Niña, also had strong AO/NAO blocking. I’m more interested to see how the QBO behaves this fall

The Nina winter of 95-96,  as you mentioned was very unusual. We had cold air and coinciding active systems, producing an abundance of snowfall.  Not your so called typical Nina by any means. 

Currently this past decade,  and even more so the last 5 years summer blocking has manifested and when the winter months evolve the previous blocking from the summer and Fall diminishes,  and even disappears.

The last couple winters had the AO and the NAO go weeks on end in the positive phase.  Snow advance, overall NH snow cover, and November blocking that some had used to forecast winter blocking ahead never took hold.  The various cause have been discussed here.  Two years in a row we had record high NH snow cover only to suffer January reversals that were sudden and unrecoverable from.  

Simply though it appears to evolve around the Hadley cell, the basin wide Pacific warmth, especially in the far SW Pacific,  the record setting fast Pac jet,  and recently you have to contemplate the strange gyrations  of the QBO. Things were never in sync to produce extended cold during the last two winters. 

I would think unless we achieve some intervals of moderate blocking in the HL and help from the extinct winter - NAO we face serious obstacles in achieving even climo snowfall during the 20-21 winter season.     

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4 hours ago, snowman19 said:

Never heard that correlation before. The thing you definitely don’t want with a Niña is +NAO/+AO due to the crap Pacific side Ninas normally produce, especially in combination with a -PDO. If you look back at the good Niña winters, they all had -NAO/-AO blocking. 08-09 had more -EPO which was a bit unusual for a Nina. 95-96 had a decent Pacific side due to the strong +PDO which was in place and highly unusual with an established Niña, also had strong AO/NAO blocking. I’m more interested to see how the QBO behaves this fall

Yea except you don’t know our climo.  In a nino winter our area and NYC can often have similar climo. It’s not that unusual for places in our region to best NYC snowfall in a nino. But in a Nina it’s a different world. Almost all the “good” Nina’s you refer to from time to time 2001,2009,2011,2013 (yes that was cold neutral but it followed 2 Nina’s and behaved like a cold Nina archetype) 2018 were utter garbage crap snowfall years here!  1996 was the only truly “good” snowfall Nina winter in the last 50 years here and 2000 was about avg across much of the area but memorable for an epic storm and 10 day period. The rest were pretty much garbage snowfall. We’re too far southwest to cash in on the northern stream miller b’s that are the main snow threats in a Nina. It took ridiculous blocking in 1996 (and March 2018 for a more contemporary example) to get our area into the action in a Nina.   

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10 hours ago, frd said:

 

Came across some posts ( research ),  maybe BAMMWX,  that alluded to a July and August -AO average correlates into a warm December in the East. 

Eh, whats new. 

 

 

ao.sprd2.gif

 

I saw something similar when researching something else last year but the correlation was very low. However, what it definitely indicated was a summer/early fall -NAO has absolutely no predictive value to a winter -NAO. I brought that up when DT used the prevalence of last simmer/fall -NAO in his winter prediction.  I’m not sure a summer -NAO necessarily has high predictive value of a positive winter NAO though. Some correlation though but low from what I remember. Makes sense. The mechanisms that could cause higher polar heights when the pole is at its warmest and the atmosphere is thicker would differ from what might impact and weaken the TPV when at its strongest!  It’s a totally different situation. 

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19 hours ago, psuhoffman said:

I saw something similar when researching something else last year but the correlation was very low. However, what it definitely indicated was a summer/early fall -NAO has absolutely no predictive value to a winter -NAO. I brought that up when DT used the prevalence of last simmer/fall -NAO in his winter prediction.  I’m not sure a summer -NAO necessarily has high predictive value of a positive winter NAO though. Some correlation though but low from what I remember. Makes sense. The mechanisms that could cause higher polar heights when the pole is at its warmest and the atmosphere is thicker would differ from what might impact and weaken the TPV when at its strongest!  It’s a totally different situation. 

Yes, I didn’t understand the correlation he made to the summer NAO either. I think what makes more sense is what they mentioned in the New England forum....That this shift to -AMO, with the associated ice cold waters in the North Atlantic, causes a positive feedback loop into the +NAO and allows it to sustain itself. As far as the AO, no offense, but I pay no mind Judah Cohen at all anymore with his SAI. Using Siberian snowcover to predict the AO has been a bust how many times now? Also, how many times have we heard “low solar/solar minimum, -AO winter incoming!”? That’s been another bust. My honest opinion, I think the arctic sea ice melt is actually re-enforcing the +NAO/+AO and making it worse

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26 minutes ago, snowman19 said:

Yes, I didn’t understand the correlation he made to the summer NAO either. I think what makes more sense is what they mentioned in the New England forum....That this shift to -AMO, with the associated ice cold waters in the North Atlantic, causes a positive feedback loop into the +NAO and allows it to sustain itself. As far as the AO, no offense, but I pay no mind Judah Cohen at all anymore with his SAI. Using Siberian snowcover to predict the AO has been a bust how many times now? Also, how many times have we heard “low solar/solar minimum, -AO winter incoming!”? That’s been another bust. My honest opinion, I think the arctic sea ice melt is actually re-enforcing the +NAO/+AO and making it worse

Not that many times, actually...only last year iirc--because we didn't start having the extended low solar until then. So technically...I'd imagine that still has one more winter to have an effect before we declare that broken as well, lol (and by comparison, we might have more successful examples of low solar working than Siberia!). For me...the last three solar minimums producing warrants one more chance...

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Best shot at a -NAO this winter is January from the NAO predictors I have. Still early though. Change from April to May and March to September as a blend is a strong NAO predictor over the past 20 years. If the NAO is near 0/neutral in September, the best blend for matching the NAO will be 1966-67 (x2), 2003-04, 2007-08. There is some tendency for very cold years to come after the solar min year (July-June basis).

NAO Sept-Mar May-Apr DJF
1975 2.17 1.08 0.23
2018 2.60 0.88 0.50
       
NAO Sept-Mar May-Apr DJF
2017 -1.35 -3.64 1.30
1994 -2.58 -1.71 1.36
2017 -1.35 -3.64 1.30
2017 -1.35 -3.64 1.30
2017 -1.35 -3.64 1.30
Mean -1.60 -3.16 1.32
2019 -1.39 -3.09 1.27

NAO was positive in March, so it will be hard for Sept-Mar to be too negative - but obviously if the NAO is very positive or very negative in September, this will change -

NAO Sept-Mar May-Apr DJF
1966 -1.01 0.97 0.01
1966 -1.01 0.97 0.01
2003 -0.31 0.19 0.07
2007 -0.72 0.49 0.65
Blend -0.76 0.66 0.18
2020 ?? 0.61  

This blend seems solid intuitively - you have four years following El Ninos, and it is a La Nina-ish blend.

Blend Dec Jan Feb Mar
1966 0.7 -0.9 0.2 1.5
1966 0.7 -0.9 0.2 1.5
2003 0.6 -0.3 -0.1 1.0
2007 0.3 0.9 0.7 0.1
Mean 0.6 -0.3 0.2 1.0
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Just read on twitter, supposedly JB thinks the QBO is going positive this fall/winter and he’s calling for an official Niña? If that’s the case then he can’t go cold and snowy on the east coast due to his explanation of why his winter forecast was a bust years ago. This should be very interesting, I have a real hard time believing he’s going to predict a warmer than average winter with below average snow for the east, I think he’s too afraid to lose his base, he’s going to spin this somehow 

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6 hours ago, snowman19 said:

Just read on twitter, supposedly JB thinks the QBO is going positive this fall/winter and he’s calling for an official Niña? If that’s the case then he can’t go cold and snowy on the east coast due to his explanation of why his winter forecast was a bust years ago. This should be very interesting, I have a real hard time believing he’s going to predict a warmer than average winter with below average snow for the east, I think he’s too afraid to lose his base, he’s going to spin this somehow 

I think you should go investigate 

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17 hours ago, yoda said:

Hope we will see some type of this again soon...

 

Did someone say Jonas?

I enjoyed that storm, earliest lock in memory and it just snowed its ass off!

I'd rank it only behind 1996 because of the second storm after that overperformed. 

Of course overall, best winter by far was 09-10.  Just don't see that around this area.  Have to head up to the lakes for that. ;)

 

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On 8/14/2020 at 6:24 PM, raindancewx said:

Best shot at a -NAO this winter is January from the NAO predictors I have. Still early though. Change from April to May and March to September as a blend is a strong NAO predictor over the past 20 years. If the NAO is near 0/neutral in September, the best blend for matching the NAO will be 1966-67 (x2), 2003-04, 2007-08. There is some tendency for very cold years to come after the solar min year (July-June basis).

NAO Sept-Mar May-Apr DJF
1975 2.17 1.08 0.23
2018 2.60 0.88 0.50
       
NAO Sept-Mar May-Apr DJF
2017 -1.35 -3.64 1.30
1994 -2.58 -1.71 1.36
2017 -1.35 -3.64 1.30
2017 -1.35 -3.64 1.30
2017 -1.35 -3.64 1.30
Mean -1.60 -3.16 1.32
2019 -1.39 -3.09 1.27

NAO was positive in March, so it will be hard for Sept-Mar to be too negative - but obviously if the NAO is very positive or very negative in September, this will change -

NAO Sept-Mar May-Apr DJF
1966 -1.01 0.97 0.01
1966 -1.01 0.97 0.01
2003 -0.31 0.19 0.07
2007 -0.72 0.49 0.65
Blend -0.76 0.66 0.18
2020 ?? 0.61  

This blend seems solid intuitively - you have four years following El Ninos, and it is a La Nina-ish blend.

Blend Dec Jan Feb Mar
1966 0.7 -0.9 0.2 1.5
1966 0.7 -0.9 0.2 1.5
2003 0.6 -0.3 -0.1 1.0
2007 0.3 0.9 0.7 0.1
Mean 0.6 -0.3 0.2 1.0

Did the PDO state play any role in this? Right now at least, it looks like a healthy negative PDO is taking shape with that big warm pool gaining strength south of the Aleutians  cdas-sflux_ssta_global_1.png

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3 hours ago, psuhoffman said:

My scientific analysis of that sst chart

567A2886-D52C-474B-B4F7-817DFDB2113A.gif.bc35c03aeb3c7f1a71d211d1163057da.gif

 

The PDO seems to be heading back to a predominately negative phase, and it might stay that way for a while. I never know what to think of it anyway, as it is clearly a response to multiple influences, and not an atmospheric driver itself. Most of the patterns/temp/precip anomalies that the PDO is associated with, have a stronger correlation to the ENSO state itself. So I suppose it is an enhancer/moderator in certain cases. We have had a recent tendency for a massive ridge in the EPAC/suppression of the Aleutian low, and combined with SST anomaly persistence, seems to argue for negative phase. The ENSO has an impact on the elements that drive the PDO (like the Aleutian low). Looking at the distribution of SSTs associated with the -/+ PDO phases, it seems logical that the cool phase should be generally favored in a Nina, and vise versa, esp during stronger ENSO events. Ofc it doesn't always work out this way.

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2 hours ago, snowman19 said:

IMO the thing that is more disturbing than the PDO right now is the -AMO. That is an ugly North Atlantic if you want negative NAO. Of course this could all be different come November....

Its all crap. Sst in the mjo domain is opposite what we want . Pdo. Enso. Atlantic everything isn’t right. I’m not wasting time debating which awful is most awful. 

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