February is upon us - pattern change is in order

[Typhoon Tip]

3 hours ago, EastonSN+ said:

The teleconnections look Beautiful.

Deeply negative AO AND NAO. Rising PNA. Falling EPO. MJO going through phases 1 and 2.

I want to see some results on the models! Also, hearing about the NAO linking up with the eastern ridge creating a disaster for snow. What does this mean and wouldn't the negative AO squash such an event?

 

Mentioned this yesterday myself...although I didn't get into the snow part - not sure how that correlation is assumed...

The best window of opportunity for a significant winter impact scenario is probably Wednesday through next weekend, after which ... that ridge/blocking node associated with the NAO still appears (per the tenor of the operational runs last night) slated to complete a retrogression journey through the western end of the NAO domain space ... then collapsing S through the Maritimes to an eventual merger with the westerlies closer to middle latitudes over the eastern CONUS.

That whole evolution should take 4 to 6 days...  As it goes, there should be one ...perhaps two significant event chances... 4-6 days isn't a huge amount of time; in fact, 6 may be generous given recent trends.  But, as we near the far end of that time range, it is not clear whether the Pacific relay into N/A will enforce the same thing we have been seeing or not - there are reasons as you intimated with the MJO, to assess it could change.  In fact, details in that part of the circulation et al will also play a significant role in what is ejected down into the region ... up under the NAO blocking as it is doing that migration pathways described above.  

It's about as complex an atmosphere the models are trying to process for as there can be.  Just the block/NAO aspect alone - the 00Z operational GFS takes that mid lvl blocking on the inside route through eastern Canada, ...showing an eventual merger farther west through the G. Lakes region... the 06z takes it plumb south, or tries too, through the outer Maritimes.  Either one of these is plausible; yet both have [probably] different stresses on the pattern and more importantly... how features embedded in the pattern evolve in space and time.  Which... if one is getting my drift ... try being particular about storm identities when there is utter obscurity as to what will even take place - good luck... 

Meanwhile, with the MJO being "modestly" coherent in Phase 8-1-2 .. yeah, the expectation for a rising PNA index is okay...But then again... it almost has to rise anyway - it can't hang around -4 SD forever. I like Will and Scott's reasoning from yesterday (if I'm gathering this rightly...) that we probably don't really need a huge perfect complexion of a western rollin' ridge to dump some hugely teleconnected negative anomaly into the OV to make winter hay out of this... The NAO dividend is that it forces troughs to maximize their mechanical power...festering in a slow movement scenario... such that you don't really need a very strong 45 vmax and mega wall of DPVA to get higher end impacts to take place.. You can get there for duration and also, if things are set up, the potency isn't exactly lacking either.   The trick with the NAO is that it can bully the flow and suppress things to nothing... or, it can evolve too far east or west ... lot of moving part there.  This, so far, doesn't look terrible at least in the operative depictions.  We are still really just dealing with establishing a really nice table-set ... no idea who the guests are that will ultimately take seat. 

[STILL N OF PIKE]

Just now, 40/70 Benchmark said:

You have been stationed in left field the vast majority of this winter.

None of that is true...zero.

Only rev can post this nonsense

[40/70 Benchmark]

2 minutes ago, STILL N OF PIKE said:

Only rev can post this nonsense

I am not saying that it can't miss...been wrong plenty of times and will be plenty more, but no one can say anything definitive at this insanely early juncture.

[Damage In Tolland]

3 minutes ago, STILL N OF PIKE said:

Only rev can post this nonsense

What nonsense? Don’t set yourself up for sadness 

[WintersComing]

4 minutes ago, Damage In Tolland said:

What nonsense? Don’t set yourself up for sadness 

You mean there won't be Days and Days of snow??

[EastonSN+]

7 minutes ago, Typhoon Tip said:

Mentioned this yesterday myself...although I didn't get into the snow part - not sure how that correlation is assumed...

The best window of opportunity for a significant winter impact scenario is probably Wednesday through next weekend, after which ... that ridge/blocking node associated with the NAO still appears (per the tenor of the operational runs last night) slated to complete a retrogression journey through the western end of the NAO domain space ... then collapsing S through the Maritimes to an eventual merger with the westerlies closer to middle latitudes over the eastern CONUS.

That whole evolution should take 4 to 6 days...  As it goes, there should be one ...perhaps two significant event chances... 4-6 days isn't a huge amount of time; in fact, 6 may be generous given recent trends.  But, as we near the far end of that time range, it is not clear whether the Pacific relay into N/A will enforce the same thing we have been seeing or not - there are reasons as you intimated with the MJO, to assess it could change.  In fact, details in that part of the circulation et al will also play a significant role in what is ejected down into the region ... up under the NAO blocking as it is doing that migration pathways described above.  

It's about as complex an atmosphere the models are trying to process for as there can be.  Just the block/NAO aspect alone - the 00Z operational GFS takes that mid lvl blocking on the inside route through eastern Canada, ...showing an eventual merger farther west through the G. Lakes region... the 06z takes it plumb south, or tries too, through the outer Maritimes.  Either one of these is plausible; yet both have [probably] different stresses on the pattern and more importantly... how features embedded in the pattern evolve in space and time.  Which... if one is getting my drift ... try being particular about storm identities when there is utter obscurity as to what will even take place - good luck... 

Meanwhile, with the MJO being "modestly" coherent in Phase 8-1-2 .. yeah, the expectation for a rising PNA index is okay...But then again... it almost has to rise anyway - it can't hang around -4 SD forever. I like Will and Scott's reasoning from yesterday (if I'm gathering this rightly...) that we probably don't really need a huge perfect complexion of a western rollin' ridge to dump some hugely teleconnected negative anomaly into the OV to make winter hay out of this... The NAO dividend is that it forces troughs to maximize their mechanical power...festering in a slow movement scenario... such that you don't really need a very strong 45 vmax and mega wall of DPVA to get higher end impacts to take place.. You can get there for duration and also, if things are set up, the potency isn't exactly lacking either.   The trick with the NAO is that it can bully the flow and suppress things to nothing... or, it can evolve too far east or west ... lot of moving part there.  This, so far, doesn't look terrible at least in the operative depictions.  We are still really just dealing with establishing a really nice table-set ... no idea who the guests are that will ultimately take seat. 

Thanks. What is also perplexing is that fact that the AO is nosediving as well. I would think that a combined deeply negative AO and NAO would team up to suppress the ridge in the east. Perhaps the "ridge" would be narrow and fall between these 2 domains? 

[weathafella]

1 hour ago, Ginx snewx said:

No sh it but we were talking about 1888

I was quoting Kevin’s post.   And true is correct.    

[STILL N OF PIKE]

4 minutes ago, Damage In Tolland said:

What nonsense? Don’t set yourself up for sadness 

Lol

Are you gonna down Play everything Like powderfreak

[Hoth]

1 minute ago, STILL N OF PIKE said:

Lol

Are you gonna down Play everything Like powderfreak

Pfreak may have good reason to downplay, but not the Rev.

[dryslot]

If i was in SNE and south into the MA i would feel pretty good right now.

[Damage In Tolland]

5 minutes ago, WintersComing said:

You mean there won't be Days and Days of snow??

There certainly could be.. but odds in this pattern historically favor the mid Atlantic until the block weakens 

[WintersComing]

2 minutes ago, Damage In Tolland said:

There certainly could be.. but odds in this pattern historically favor the mid Atlantic until the block weakens 

Come on Kev........we need your mojo back!!!

[40/70 Benchmark]

11 minutes ago, EastonSN+ said:

Thanks. What is also perplexing is that fact that the AO is nosediving as well. I would think that a combined deeply negative AO and NAO would team up to suppress the ridge in the east. Perhaps the "ridge" would be narrow and fall between these 2 domains? 

The PNA modulates the re ridge in a big way. RNA teleconnects to a se ridge,

[Hoth]

6 minutes ago, Damage In Tolland said:

There certainly could be.. but odds in this pattern historically favor the mid Atlantic until the block weakens 

If we have a strong +PNA coinciding with the strong -NAO I would agree, but with west coast troughing I'd think it'll be harder for systems to get buried in the South.

[40/70 Benchmark]

9 minutes ago, Damage In Tolland said:

There certainly could be.. but odds in this pattern historically favor the mid Atlantic until the block weakens 

I would like to know how many examples there are of a KU event in the mid atl during a bonafide RNA pattern.....honest question.

No sarcasm...there may be some, but the utility would be to compare those H5 plots to modeled day 7 charts.

60s may have had some...maybe Jan 2011?

[Damage In Tolland]

1 minute ago, 40/70 Benchmark said:

I would like to know how many examples there are of a KU event in the mid atl during a bonafide RNA pattern.....honest question.

No sarcasm...there may be some, but the utility would be to compare those H5 plots to modeled day 7 charts.

I’m not ruling anything out. Just not as enthusiastic about the pattern as some are

[40/70 Benchmark]

The RNA is evolving into a PNA as this all unfolds, which while potentially fueling the development of a storm via additional mass shifts, still is not yet a bonafide PNA.

There is modularity there.....not yet established PNA mode.

[EastonSN+]

3 minutes ago, 40/70 Benchmark said:

I would like to know how many examples there are of a KU event in the mid atl during a bonafide RNA pattern.....honest question.

No sarcasm...there may be some, but the utility would be to compare those H5 plots to modeled day 7 charts.

60s may have had some...maybe Jan 2011?

What us the RNA? Is there a chart?

[40/70 Benchmark]

2 minutes ago, Damage In Tolland said:

I’m not ruling anything out. Just not as enthusiastic about the pattern as some are

Oh, that is totally fair.

I misunderstood you, then.

[40/70 Benchmark]

2 minutes ago, EastonSN+ said:

What us the RNA? Is there a chart?

RNA is the inverse of a PNA.

Its currently very negative...I'm in the office, but I'm sure Steve has the chart in his wallet.

[Whineminster]

Ok, one storm at time and first things first.  Let's talk about the icing threat tonight and then again Saturday night into Sunday.  Could get dicey.  Looks like a nice little shot of snow for NNE. 

[weathafella]

Anything south of SNE in this pattern is likely wet vs white.   Ensembles clearly show this.

[40/70 Benchmark]

8 minutes ago, Hoth said:

If we have a strong +PNA coinciding with the strong -NAO I would agree, but with west coast troughing I'd think it'll be harder for systems to get buried in the South.

Bingo.

[dryslot]

Looks like a good shot of 3-6"+ of snow inland with a mix to rain on the coast up here into CNE and some of NW MA.

[40/70 Benchmark]

18 minutes ago, Whineminster said:

Ok, one storm at time and first things first.  Let's talk about the icing threat tonight and then again Saturday night into Sunday.  Could get dicey.  Looks like a nice little shot of snow for NNE. 

 

The onus is on you to start a thread since its 48 hours out.

[Typhoon Tip]

30 minutes ago, EastonSN+ said:

Thanks. What is also perplexing is that fact that the AO is nosediving as well. I would think that a combined deeply negative AO and NAO would team up to suppress the ridge in the east. Perhaps the "ridge" would be narrow and fall between these 2 domains? 

Mmm, there is no direct pathway between the AO and the SE ridge in terms of forcing, tho. That's an indirect causality there... with perhaps more than a couple moments of indirection.  

One thing ... you may know this already but, the AO and NAO merely share domain space.  The overlap is ...perhaps 1/3 to 2/5ths the planetary coordinates.  This is true all around the hemispheric 'cap' of the AO index's domain space; the EPO also shares domains space similarly ..roughly, similarly.

All these teleconnectors are, are regions that are identified as having statistical correlation to other regions.  -NAO "tends" to mean higher heights over Greenland, ...and counterbalancing for mass conservation, you have a negative regions - in total = 0 loss.  That's really why the correlations even exist... because mass cannot be lost or destroyed.. it's merely moving from point A to B in three dimensional space.

Example: You can have a singular node/blocking ridge feature, with a pearled out string of counter-balancing negatives that individually ... one is not sufficiently negative as the ridge is positive, but... 0 loss is achieved in the aggregate - i.e., all of them together  ( -L1 + -L2 + -L3 + -L4) + (+H1) = 0  ... or vice versa, (-L1) + ( +H1 + + H2 ...) = 0.  The left side of that equation is the constant motion of the three-d mentioned above.

So, bringing this home... the AO can be negative and never feature much impact locally to our hemisphere, because all it's counter-balancing phenomenon didn't happen to evolve on our side.  More over, the NAO could go through a negative phase state, and the AO can conceivably stay positive at times ...due to the fact that they only share space.  So you can't really "assume" a -AO will "combine" with a -NAO to battle the SE ridge... that's not really how it works.  And in fact, the SE ridge can remain in place while a -NAO evolves and all it does is compress and blast the hell out of the wind field at mid levels from Texas to Bermuda... .. The SE ridge is really put there by the Pacific for that source of headache tele's ..

 

[40/70 Benchmark]

If anyone has the Kocin book handy, or is in front of a reanalysis site....take a look at our historic whiffs....AKA, January 2016, Feb 2010, PD I.....my guess is that had a negative NAO/+PNA couplet.

[Cold Miser]

...What a great series of posts.  A potential storm, 7+ days away and we are worried about the DC Weather Gang stealing our snow already.

[40/70 Benchmark]

1 minute ago, Cold Miser said:

...What a great series of posts.  A potential storm, 7+ days away and we are worried about the DC Weather Gang stealing our snow already.

I'm not sure why anyone would discuss the long range modeled pattern in the model thread.

Anarchy....chaos.

[HoarfrostHubb]

11 minutes ago, dryslot said:

Looks like a good shot of 3-6"+ of snow inland with a mix to rain on the coast up here into CNE and some of NW MA

NAM looks pretty icy/mixed bag for elevations near the MA/NH border