December 2021

[EasternLI]

27 minutes ago, Brian5671 said:

that had a big -EPO.  We would need something like that to turn this around

I was just having a little fun. Can't be serious all the time. The world could use a little more levity. 

[RippleEffect]

seattle expecting snow the next two weeks. lucky them

[MJO812]

Brian gives me a weenie for saying what the model shows

Definition of a troll

[SnowGoose69]

FWIW the 18Z NAM is taking a step towards the 12Z Euro with that 12/24 event

[the_other_guy]

23 minutes ago, RippleEffect said:

seattle expecting snow the next two weeks. lucky them

Very rare and Almost always a bad sign for our snow chances

[MJO812]

12 minutes ago, SnowGoose69 said:

FWIW the 18Z NAM is taking a step towards the 12Z Euro with that 12/24 event

Yep further south 

[Brian5671]

19 minutes ago, jfklganyc said:

Very rare and Almost always a bad sign for our snow chances

every once in awhile it works out-Dec 08 had snow in Seattle AND the east coast-coast to coast cold-but it's rare.   

[snowman19]

6 hours ago, bluewave said:

It’s tough to shift the Aleutian Block and deep -PNA once it becomes a self sustaining process. Paul Roundy gives a nice explanation of what has been going on. This is why we are seeing the record Aleutians Ridge and -PNA this month. So it’s no surprise that all the models continue this pattern into the long range.

 

Yes. The main source of the signal is the Rossby wave breaking drops cutoff Cyclones into the tropics that become the equatorial Rossby waves. The waves move Westward and become convective, driving a synoptic response into the extra tropics, forming a feedback loop.

I was looking at this earlier….that positive feedback loop is going to keep that -PNA/Aleutian ridge in place, it’s a self-sustaining process, definitely not good news, especially when you couple that with possible IO convection taking shape mid-January

[the_other_guy]

6 minutes ago, Brian5671 said:

every once in awhile it works out-Dec 08 had snow in Seattle AND the east coast-coast to coast cold-but it's rare.   

Yes they need such an extreme pattern to get accumulating snow… 

 

If you get your jollies off other peoples driving misery… YouTube Seattle snow icy roads. Hours of entertainment

[EasternLI]

08-09 was actually not a terrible analog in the fall. Without this record -PNA I wonder if we could have seen that coast to coast trough with the -NAO. They are rare. 

[SnowGoose69]

9 minutes ago, Brian5671 said:

every once in awhile it works out-Dec 08 had snow in Seattle AND the east coast-coast to coast cold-but it's rare.   

December 1990 also...honestly the pattern right now at 500 over the US is pretty close to what it was in December 1990, the NAO/AO was strongly positive that month though

[snowman19]

2 hours ago, EasternLI said:

14-15 was a furnace December.

Not calling for that, but that winter turned out fine. I've seen some fat squirrels this year too. Let me get the farmers almanac. Nope, we're porked, we had a full moon in August. 

If there was anything concerning, it’s this (SPV). IMO, this is definitely not what you want to see happen in January. Especially since the already in place synoptic tropospheric forcing/drivers are not going anywhere soon  

 

[SnoSki14]

7 minutes ago, snowman19 said:

If there was anything concerning, it’s this (SPV). IMO, this is definitely not what you want to see happen in January. Especially since the already in place synoptic tropospheric forcing/drivers are not going anywhere soon  

 

On the contrary it's great if you want a warm, dry winter.

We're probably gonna be shut out until late winter. Could the entire winter be a dud, sure but still think the blocking comes through late. 

Meanwhile a historic winter is on its way in the Pacific NW. Unusually chilly temperatures down to CA as well.

[EasternLI]

4 minutes ago, snowman19 said:

If there was anything concerning, it’s this (SPV). IMO, this is definitely not what you want to see happen in January. Especially since the already in place synoptic tropospheric forcing/drivers are not going anywhere soon  

 

That's definitely a possibility. Not sold on that just yet though. Going to need to see how this pattern actually shakes out. The MJO being stuck in phase 7 like it is argues for a different outcome. And it seems we could be stuck for a couple weeks with that feedback loop. Just need to keep tabs on it for a while. 

[Brian5671]

central/northern NE cashing in on some snow next 7-10 days.  Hopefully that gradient will drift south a bit especially heading into the coldest climo of the year....

[MJO812]

22 minutes ago, SnoSki14 said:

On the contrary it's great if you want a warm, dry winter.

We're probably gonna be shut out until late winter. Could the entire winter be a dud, sure but still think the blocking comes through late. 

Meanwhile a historic winter is on its way in the Pacific NW. Unusually chilly temperatures down to CA as well.

You change your mind so much it's amazing 

[MJO812]

15 minutes ago, EasternLI said:

That's definitely a possibility. Not sold on that just yet though. Going to need to see how this pattern actually shakes out. The MJO being stuck in phase 7 like it is argues for a different outcome. And it seems we could be stuck for a couple weeks with that feedback loop. Just need to keep tabs on it for a while. 

Hopefully it's a slow movement through 8

[SnoSki14]

5 minutes ago, MJO812 said:

You change your mind so much it's amazing 

My thinking is not much happens until late winter (late Feb through March). 

If anything were to happen before that then it'd be in 1st half of Jan. Overall think 30" is possible from a late winter assault. 

Blocking returns in tandem with favorable PNA relative to climo. 

[MJO812]

1 minute ago, SnoSki14 said:

My thinking is not much happens until late winter (late Feb through March). 

If anything were to happen before that then it'd be in 1st half of Jan. Overall think 30" is possible from a late winter assault. 

Blocking returns in tandem with favorable PNA relative to climo. 

Quite possible 

[North and West]

On the contrary it's great if you want a warm, dry winter.
We're probably gonna be shut out until late winter. Could the entire winter be a dud, sure but still think the blocking comes through late. 
Meanwhile a historic winter is on its way in the Pacific NW. Unusually chilly temperatures down to CA as well.

.

[EasternLI]

Those Pacific warm pool waters we talked about in here really are the driving force of all of this. Be interesting to see what does actually break this loop. Phase 7 until further notice until some event shows up to disrupt this. But phase 7 is very capable of strat disruption as per the literature. La Niña plus EQBO is also favorable for doing that. The -PNA is a complimentary component to this. So do we break the loop before enough damage is done? Or does the strat eventually break the loop? I'd be a little surprised honestly if the MJO were to make a push east with this going on. Thinking it needs an intervening force. Just not sure what ultimately happens with this or what that force will be. 

 

[snowman19]

19 minutes ago, EasternLI said:

Those Pacific warm pool waters we talked about in here really are the driving force of all of this. Be interesting to see what does actually break this loop. Phase 7 until further notice until some event shows up to disrupt this. But phase 7 is very capable of strat disruption as per the literature. La Niña plus EQBO is also favorable for doing that. The -PNA is a complimentary component to this. So do we break the loop before enough damage is done? Or does the strat eventually break the loop? I'd be a little surprised honestly if the MJO were to make a push east with this going on. Thinking it needs an intervening force. Just not sure what ultimately happens with this or what that force will be. 

 

That’s the thing, I don’t think we break this feedback loop anytime soon, this is quite the self-sustaining system we have in place right now. IMO if you want to see a big shakeup, it would be a major SSW and there’s just no signs of that yet. In fact, it appears the SPV gets very strong the 1st week of January. I read the literature you spoke of and it’s definitely promising for a SSW, assuming we actually follow climo….but what is normal climo lately? Lol If we get into late January and we still have a strong SPV with no signs of a SSW and the same tropospheric feedback loop in place, it will not be good to say the least. Plenty for us to watch the next few weeks and good pickup on your part with those very warm waters in phase 7 helping to sustain the wave there. I’m sure you saw ENSO Region 4 is the coldest its been in many years, one of the coldest in over the last 40 years in fact….like you said it’s going to be very difficult for that MJO to propagate east, the cold waters are going to kill the T-storm activity: 

 

[snowman19]

Want to see a semi-permanent positive feedback loop in action? Here you go: 

 

[EasternLI]

1 minute ago, snowman19 said:

That’s the thing, I don’t think we break this feedback loop anytime soon, this is quite the self-sustaining system we have right now. IMO if you want to see a big shakeup, it would be a major SSW and there’s just no signs of that yet. In fact, it appears the SPV gets very strong the 1st week of January. I read the literature you spoke of and it’s definitely promising for a SSW, assuming we actually follow climo….but what is normal climo lately? Lol If we get into late January and we still have a strong SPV with no signs of a SSW and the same tropospheric feedback loop in place, it will not be good to say the least. Plenty for us to watch the next few weeks and good pickup on your part with those very warm waters in phase 7 helping to sustain the wave there. I’m sure you saw ENSO Region 4 is the coldest its been in years, one of the coldest in over the last 40 years in fact….like you said it’s going to be very difficult for that MJO to propagate east, the cold waters are going to kill the T-storm activity: 

 

That's exactly why I think we'll know more by mid January. If we haven't seen at least signs of anything by then, with the pattern locked in like this. It's probably not going to work out. I have 2 scenarios in my mind. Either we get the ssw and associated -AO. Or we don't. In which case we'd probably come around to the +AO in short order and that's not going to do anything for us. 

[donsutherland1]

Another push of modestly colder air will bring down temperatures tomorrow, but a generally mild remainder of December lies ahead.

It will be a different story in the Pacific Northwest. Near record to record cold, along with snowfall, is possible during the closing days of December in such cities as Portland, Seattle, and Vancouver.

January will likely commence with an AO-/PNA- pattern. That typically favors somewhat cooler than normal readings in the East. For NYC, the January 1-10, 1991-2020 mean temperature for such cases was 33.5° (normal: 34.8°).

The latest guidance suggests that temperatures could head toward seasonal levels and then below seasonal levels as the first week of January progresses. The coldest air will likely remain confined to the Pacific Northwest, Northern Plains, and western and central Canada. No severe cold is likely through at least the first week of January. There are some hints that a milder pattern could begin to develop around mid-January.    

In the Midwest, through 4 pm today, Chicago has yet to receive its first measurable snowfall. The old record latest first measurable snowfall was December 20, 2012.

Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19.

The ENSO Region 1+2 anomaly was -1.7°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 15. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.93°C. La Niña conditions will likely persist through meteorological winter.

The SOI was -12.87 today.

The preliminary Arctic Oscillation (AO) figure was -1.704 today.

On December 20 the MJO was in Phase 7 at an amplitude of 2.096 (RMM). The December 19-adjusted amplitude was 1.615 (RMM).

Based on sensitivity analysis applied to the latest guidance, there is an implied 99% probability that New York City will have a warmer than normal December (1991-2020 normal). December will likely finish with a mean temperature near 42.9° (3.8° above normal).

 

[EasternLI]

1 hour ago, EasternLI said:

08-09 was actually not a terrible analog in the fall. Without this record -PNA I wonder if we could have seen that coast to coast trough with the -NAO. They are rare. 

Well, there it is. 2008-09 shows up in an unpopular way. 

 

[EasternLI]

15 minutes ago, bluewave said:

It may take a SSW to shake up this very persistent ArL regime.

 

 

Yeah, I'm struggling to see another way out. Although, if there was a recurving tropical system or something that could be another plausible way I suppose. Some kind of powerful force. That's probably not what we would prefer. As it would alleviate pressure on the PV though. Need phase 7 to do some work. 

[EastonSN+]

47 minutes ago, EasternLI said:

Well, there it is. 2008-09 shows up in an unpopular way. 

 

I would take 08/09 in a heartbeat.

Above average snowfall winter but icy 

[EasternLI]

4 minutes ago, EastonSN+ said:

I would take 08/09 in a heartbeat.

Above average snowfall winter but icy 

I would have no issues at all with 08-09 here either. SSW event that winter too. Hopefully we can step up to the ssw roulette wheel and give it a spin. 

[StormchaserChuck!]

1 hour ago, EasternLI said:

Well, there it is. 2008-09 shows up in an unpopular way. (Dec 26, 2008 last strongest daily -PNA until today)

-NAO was stronger