Absolute Vorticity

Bgoney wrote: ↑Sat Oct 16, 2021 9:11 am Whew! Nice post Les .


Lots of early signs that look favorable for a descent start to winter. We always have to be on the lookout for that one overpowering anomaly that spoils the rest of the basket such as recent years ,ae, IOD,AO. ATM, neither of these look to spoil the bunch. LaNina looks to stay in check as you mentioned.. MJO has been a thorn in our winter behinds in recent years . Over the last month its been in the maritmes , which has been good for helping shutting down the tropical season during that period and hopefully gets that location out of its system for winter. -EPO of course is crucial for the OV , without it the advance of arctic air stays in the plains and midwest. Then there is the QBO which looks good atm , but needs to put the brakes on , I forget what year recently but a too -QBO bit us in the butt at that time. All things to keep an eye on course over the next 2-4 weeks

Thanks Bgoney! My post was one of those drink a cup of coffee this morning, and try and digest all of it kind of thing. Seriously though, the EPO is a concern. With the cooling we're seeing in the Gulf of Alaska, if that becomes a perm fixture say after mid November then the EPO is probably going to avg out to be positive and like you said, that's no good at all. I'm just hoping that it won't happen that way and the blocking up top (AO and NAO domains) can help offset the -PNA as I mentioned in my post last night. That should keep the SE ridge from becoming too strong, esp early on in the winter. But I am watching the EPO no doubt. Then as far as the QBO goes, a value of -15 to -25 is concerned a moderately strong -QBO and I think we're okay if it stays in that range. I'd like to see it continue dropping into that range then start to rise say by Dec or Jan. That would bode well for the back half of winter IMO. Since you mentioned a strongly -QBO killing us due to a howling Pacific Jet, that winter was 2007-2008. That was the season of Cutter after Cutter after Cutter until March of 2008 finally came thru for us. That was a strong Nina by the way and that was when places like Milwaukee, Chicago, Detroit, and Toledo all had record setting snowfall for that winter as a whole. We were just too far SE to cash in until that March storm of course. It was def a Plains and Upper Midwest winter and the Western Great Lakes. I would like to see that pattern repeat just a few hundred miles further to the SE with the gradient or baroclinic boundary. SE ridge was just too much for the OV but if we can keep it weaker due to the arctic blocking, then we've got a shot at some fun here locally. As always, we'll see!

Speaking of the EPO, it was mainly negative this year until about August and it's been positive as a whole since then. It is usually not of a concern this time of year but in another month, it could be. The link below shows daily EPO values since 1948 so scroll down towards the bottom to see how it has trended in the last few months.

ftp://ftp.cdc.noaa.gov/Public/map/telec ... resent.txt

Looks like Josh and company have released their winter outlook from the SWC Forecasting Center. Always a good read of course, so be sure to check it out.

https://swcforecastcenter.com/united-st ... bK91jLEdMg

My own thoughts after reading it are that I can't really disagree with any of it at all. They have us on the fence which is exactly where we usually are most winters anyway. Potential for above normal precip and snow are there with around normal for temps. Looking like colder with much above normal snowfall for folks N of I-70. Active and stormy are the key take always from the forecast and I think the outlook covers well the things to keep an eye on over the next month. We've mentioned it here. The Gulf of Alaska low, blocking in the Arctic and SSW events, should they occur. I think Josh's outlook agrees with a lot of things we've been discussing on this forum also.

Josh, if you see this post and get a chance, do you mind giving us a few more technician nuggets and some of the analog years that you used. Thanks!

Ice growth compared to last year at same time is way ahead. Granted ,last year was at record lows , but nice to see a recovery when some say it can't

Huge difference for sure and it is nice to see. We're going to have cold air production and a weak PV. It'll be a matter of where it goes as usual.

LaNina still steadily building

I am still discounting strong. I could see a moderate peak though. A moderate followed by another moderate has only happened once since 1950. Never had a moderate followed by a strong before. Typically a second year Nina is on the weaker side so it remains to be seen what impacts this will have on our winter, esp if it does peak at moderate. Again, when? And how fast does it collapse will also have implications. Just too soon for me to tell honestly. I still like a change to colder and an early start to winter come mid to late November. How long can that last is the ultimate question.

tron777 wrote: ↑Wed Oct 20, 2021 6:32 am I am still discounting strong. I could see a moderate peak though. A moderate followed by another moderate has only happened once since 1950. Never had a moderate followed by a strong before. Typically a second year Nina is on the weaker side so it remains to be seen what impacts this will have on our winter, esp if it does peak at moderate. Again, when? And how fast does it collapse will also have implications. Just too soon for me to tell honestly. I still like a change to colder and an early start to winter come mid to late November. How long can that last is the ultimate question.

On the same page again Les. Also,different models show different strengths and also different outcomes over the next few months. I am going on the low end La Nina from what I am seeing but again I could get burned by this if it becomes stronger than what I see happening.

tpweather wrote: ↑Wed Oct 20, 2021 6:37 am

tron777 wrote: ↑Wed Oct 20, 2021 6:32 am I am still discounting strong. I could see a moderate peak though. A moderate followed by another moderate has only happened once since 1950. Never had a moderate followed by a strong before. Typically a second year Nina is on the weaker side so it remains to be seen what impacts this will have on our winter, esp if it does peak at moderate. Again, when? And how fast does it collapse will also have implications. Just too soon for me to tell honestly. I still like a change to colder and an early start to winter come mid to late November. How long can that last is the ultimate question.

On the same page again Les. Also,different models show different strengths and also different outcomes over the next few months. I am going on the low end La Nina from what I am seeing but again I could get burned by this if it becomes stronger than what I see happening.

I think the CFSV2 is too cold so I am tossing that solution out the window. High end weak or even a moderate as I've said before is possible, so yeah, we continue to be on the same page for sure.

I find this graphic to be interesting. With 2nd year Nina's, the majority of the time, we get above avg precip. So an active winter would be likely. Doesn't mean mild and wet all the time. It can mean above normal snow too if the pattern is right. We're just talking above normal precip.

That pretty much matches NOAAs generic precip winter Outlook. I'd rather not show the temp outlook

Bgoney, I saw it and already know. This icon says it all:

I do like the call of a change to colder sometime in that mid to late November timeframe. I am seeing more and more long term guidance starting to show that change with more of a +PNA look. So a ridge along the West Coast of North America and a trough in the East. The timing remains to be seen this far away of course. How cold can we get remains to be seen? Any flakes? How long does this last? All questions we need to answer down the road in the coming weeks. I feel good about it and the long term data is starting to support it. It is typical Nina climo also to have a change around that time with the torch conditions we've had for the last few weeks. I think the longer it waits, the better off for December, we're going to be. So I am perfectly fine waiting until the Nov 15-25th period for the change to come. We'll see what happens. Models are models and reality is reality. But my thinking is still on track for this and I am not seeing any red flags yet to change this line of thinking with an early start to our winter.

Here's a pretty cool animation showing how quickly the arctic sea ice is developing.

Also of note... look at the comparison of the SST's from last year's La Nina to the current La Nina. The North Pacific cooling down is clearly evident and we did not have that last winter at all. It was a +PDO. This second year Nina, is clearly going to have a -PDO. This is more like the typical gradient Nina winters we've had in the past like 2007-2008 and 2008-2009. We know what happened in 07-08. Record setting snows for the Midwest and Lakes. A huge gradient winter. We got screwed on every case until the March of 2008 storm saved our winter. 2008-2009 was a second year Nina and it's not a bad analog for this winter either. For the 08-09 winter, November was warm with only a T of snow at CVG. December, was colder then normal but not a lot of snow for CVG only 2". We had too many mixing issues here so bad luck in an otherwise decent pattern. Jan of 09 was good. Colder then normal and 14" of snow at CVG. I will never forget that nice 3 day winter storm we had Jan during the 27-29th. Snow, ice, and sleet all occurred. It was snow changing to ice / sleet with the first round, then snow on the backside of it with a wicked deformation zone! I loved it personally. Feb had a lot of up's and downs and skewed warmer but we cashed in nicely on 2/3 with a snow event where 5-6" fell at CVG. 7" total for the month. March had no snow at all with warmer then avg temps. So that wasn't really a bad winter at all IMO. 23" total fell at CVG and using the new climate normals you could say it was an avg winter. However, a lot of the time, we had bad luck in an otherwise good pattern and that happens. I would absolutely roll the dice again. If the blocking keeps up and is in the correct spot, we can do better then both of those winter: 07-08 and 08-09 in my honest opinion. Anyway... enough rambling. Here are those SST maps for comparison that I spoke of.



Current SST's:


Last Year SST's:

I think this is hilarious!!! No snowfall forecast because snowfall is generally not predicted more than a week in advance? You've got to be kidding me, as if rainfall and temperatures can be accurately predicted through February at the end of October.

dce wrote: ↑Fri Oct 22, 2021 8:10 pm I think this is hilarious!!! No snowfall forecast because snowfall is generally not predicted more than a week in advance? You've got to be kidding me, as if rainfall and temperatures can be accurately predicted through February at the end of October.

Agreed Doug... kind of a pointless tweet. But I get it. We will see an active and stormy winter. Just hope it's more of the white kind versus the wet kind.

I don’t know if this website is accurate and correct me if I’m wrong but this is going to be the first time we’ve seen back to back moderate La Niñas. This can’t be overlooked IMO and this would put a major strain on finding analogs to compare
https://ggweather.com/enso/oni.htm

This is going to be very interesting. I’ve noticed also that there are no anomalous westerly zonal wind anomalies in the artic stratosphere (usually you see some), and the second thing I’ve noticed is the Aleutian low is present more than it’s not (this is very El Niño like and not La Niña like). This could flip but thought it was worth noting regardless

On a whim I checked the euro weeklies and the gefs and both have a 30 day average to November 20 of the favored Aleutian low set up. I still say very interesting Thoughts anyone?

Phr0z3n wrote: ↑Sat Oct 23, 2021 10:48 am I don’t know if this website is accurate and correct me if I’m wrong but this is going to be the first time we’ve seen back to back moderate La Niñas. This can’t be overlooked IMO and this would put a major strain on finding analogs to compare
https://ggweather.com/enso/oni.htm

This is going to be very interesting. I’ve noticed also that there are no anomalous westerly zonal wind anomalies in the artic stratosphere (usually you see some), and the second thing I’ve noticed is the Aleutian low is present more than it’s not (this is very El Niño like and not La Niña like). This could flip but thought it was worth noting regardless

Hey Phr0z3n! First off, welcome back! Glad to see you've returned. In case you are wondering why things look so different, our old forum crashed in late February, and we lost everything in the process. So we've got a new site and look now so everyone has had to re-create their account.

Back to the weather and the closest analog I can find is 2010-2011 (strong Nina and a good winter for us surprisingly) followed by the Mod Nina of 2011-2012 which is a terrible winter. If the Nina does remain weak, then you could always try 2007-2008 (strong Nina) followed by 2008-2009 (weak Nina and not a bad winter at all). But yeah, we have very little to go by here with this set up. The moderately -QBO should have a say and the weak PV, should it remain weak will be good. The PDO is negative this winter so it's the complete opposite of last winter where it was positive. It will be interesting as you said. I'd love for a -PNA as long as the blocking maintains itself, we should be in for some fun. A lot of If's here, but that is always the case in weather.

Phr0z3n wrote: ↑Sat Oct 23, 2021 10:57 am On a whim I checked the euro weeklies and the gefs and both have a 30 day average to November 20 of the favored Aleutian low set up. I still say very interesting

Thoughts anyone?

The only thing in the GEFS / Euro Weeklies images that I don't like is the location of the PV. I don't like seeing it on that side of the globe. We really need it under the Canadian block on our side. Luckily this isn't December yet of course, just saying...

Sorry to hear about the old forum crashing but thanks for the welcome back! You hit it right in the head of the nail about the PDO. Right now it’s suppressing the La Niña signal and that’s why it looks El Niñoish. That’s a very impressive warm pool fueling the negative PDO.

tron777 wrote: ↑Sat Oct 23, 2021 11:07 am

Phr0z3n wrote: ↑Sat Oct 23, 2021 10:57 am On a whim I checked the euro weeklies and the gefs and both have a 30 day average to November 20 of the favored Aleutian low set up. I still say very interesting

Thoughts anyone?

The only thing in the GEFS / Euro Weeklies images that I don't like is the location of the PV. I don't like seeing it on that side of the globe. We really need it under the Canadian block on our side. Luckily this isn't December yet of course, just saying...

I agree but your blocking is coming. 10hpa is already seeing warming above the artic in the stratosphere. I really like the descending signal from the stratosphere to the troposphere. Zonal wave 1 is a tad bit stronger than last year at this time which could make the argument to early start for winter. Without any westerly zonal anomalies the easterly zonal anomalies aka -QBO will really feed warming from the tropics poleward to the artic stratosphere.

Phr0z3n wrote: ↑Sat Oct 23, 2021 10:48 am I don’t know if this website is accurate and correct me if I’m wrong but this is going to be the first time we’ve seen back to back moderate La Niñas. This can’t be overlooked IMO and this would put a major strain on finding analogs to compare
https://ggweather.com/enso/oni.htm

This is going to be very interesting. I’ve noticed also that there are no anomalous westerly zonal wind anomalies in the artic stratosphere (usually you see some), and the second thing I’ve noticed is the Aleutian low is present more than it’s not (this is very El Niño like and not La Niña like). This could flip but thought it was worth noting regardless

Jason, always glad when you are posting, So much knowledge and very grateful when you share with us. Very interesting set up and want to go back to last November and get your thoughts on what happen in much of northern Siberia with tons of heavy snow very far north when its usually just dry and cold at that time of year. I had never seen that kind of heavy snow so late in the season and imo this delayed winter last season and once it let go we saw what happen in February.

Concerning this season so far and very mild in northern and central Canada so far and yes starting to get colder but this a very late start to their cold season. Not sure what this means and maybe you have some insight on this as well.

Phr0z3n wrote: ↑Sat Oct 23, 2021 11:27 am I agree but your blocking is coming. 10hpa is already seeing warming above the artic in the stratosphere. I really like the descending signal from the stratosphere to the troposphere. Zonal wave 1 is a tad bit stronger than last year at this time which could make the argument to early start for winter. Without any westerly zonal anomalies the easterly zonal anomalies aka -QBO will really feed warming from the tropics poleward to the artic stratosphere.
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Outstanding posts!!! I agree about the blocking too. That Hudson Bay block has been very persistent. You can call it a west based -NAO for the most part. With the weak PV, the AO should stay negative as well. In order for the cold to really get Canada filled up for our storm systems to tap into this winter, what are your thoughts on the EPO? It needs to be negative for that to happen as you know. It's been positive as a whole since August. (Was negative before that).

EDIT: Too add, isn't the WPO very negative right now? If yes, doesn't that usually mean a more poleward North Pacific ridge? That usually makes it easier for the EPO to turn negative.