Winter 2014-2015 Pattern Discussion Thread I

[Jon]

For me I don't understand why people are saying "ugh another 10 days away...likely wont happen, the models always say that" or something of that sort. ...it's only 12/16....exactly 10 days away from 12/26 which I have mentioned before that's when the pattern change will start to occur, meaning by christmas you're not going to see an amazing pattern in place already. Christmas into the New Year has always been the thought or I have assumed. I think the Euro weeklies have thrown some people for a loop, I don't blame you, I just don't believe them 100%. I posted on when the -NAO is supposed to show up and that's around christmas and still on track if not trending earlier. -AO still on track too. +PNA will break down and rebuild by 1/1 which is when both -AO and -NAO will be solid. I think for the new year we might see people screaming Polar Vortex on TV again.

 

There's a drop in the NAO the last two runs of the Euro OP has seen...diving at christmas. GFS Ensembles are similar with timing

 

GEFS NAO:

 

As you can see the latest run takes it neutral around the 24th when the last runs had it on 12/26....negative before Christmas....

 

EPS AO what do we see here, same thing neutral by 24th at 00z

 

and the EPS NAO? neutral by the 24th at 00z

 

 

NAO on top, AO on bottom...You can see the operational runs of the Euro are starting to sniff this out, last two runs at 216-240 hours, so the OP is getting in range of the pattern change (10 day)

 

Canadian OP AO what do we see? Again neutral at 24th 00z...Candadian ensemble NAO shows the same thing, Neutral by 24th...didn't post to save space on this long image post.

 

We know the +PNA is set to break down and dive negative, how deep that dive goes is up in the air...Euro takes it down far by the 26th, but the GFS isn't the same, notice the 12z PARA run (and the regular GFS is similar ) rebuilds it back early

 

Individual GFS 06z ensemble members you can see the PNA evolving back to positive after the 29th or so, most of you don't want to wait but unfortunately it will take a negative to neutral DIP in the LR and go back positive for the new year.

 

Lastly, check out the EPO (GEFS ensembles)....that date look familiar?

 

and here's all the members....

[Jon]

continued....

 

Look at the cold at 850mb centered over eastern Canada on the Canadain ensemble in the LR

And the Euro ens at 240...ensembles cold deep after 240 just can't post the wxbell map.

and the GFS ens

So in short, is the cold coming? Yes...can it come earlier? Yes. Will it come by the new year? Yes. 0C 850s in the deep south for a storm around new years or after is fine with me. If anything I'd hope it doesn't get too suppressive.

[packbacker]

Days 11+ on the GEFS look great for something, so maybe something right around New Years...per GEFS.  Be nice if EPS was somewhat in agreement though...

 

Edit:  Just noticed, the lower heights/jet have almost completely wrapped up the block.  By day 15 it's practically wrapped.n  Not sure if I have ever seen that before.

[griteater]

The GFS Ensemble is good, we can ride with that.  The Euro Ens gets chilly after the Christmas storm, but then it goes into some SE ridging / troughing out west.  Maybe we split the diff, I don't know, but would rather have the Euro on board between the two.  Either solution is better than what we have right now

[CAD_Wedge_NC]

So in short, is the cold coming? Yes...can it come earlier? Yes. Will it come by the new year? Yes. 0C 850s in the deep south for a storm around new years or after is fine with me. If anything I'd hope it doesn't get too suppressive.

Good post Jon.... I agree, the pattern change is imminent.

[DaculaWeather]

The GFS Ensemble is good, we can ride with that.  The Euro Ens gets chilly after the Christmas storm, but then it goes into some SE ridging / troughing out west.  Maybe we split the diff, I don't know, but would rather have the Euro on board between the two.  Either solution is better than what we have right now

Bastardi was excited about what looked like a little ridging in the SE on the Euro. He saw that as trouble, ie "stormy".

[griteater]

Bastardi was excited about what looked like a little ridging in the SE on the Euro. He saw that as trouble, ie "stormy".

 

But that would most likely keep the cold to our north unfortunately (if it is right)

 

 

This does look good on the 12z GFS Ens

 

[DaculaWeather]

But that would most likely keep the cold to our north unfortunately (if it is right)

 

 

This does look good on the 12z GFS Ens

 

 

Seems like a long time since we've seen that! 

[SnowNiner]

But that would most likely keep the cold to our north unfortunately (if it is right)

 

 

This does look good on the 12z GFS Ens

 

 

 

I guess like some storms, it's a model war for the pattern too...If the GFS/GEFS is right, the PNA is positive with lower heights in the SE.  Then the SE ridge is not a problem.  If EURO is right PNA stays negative for a while longer causing heights to raise in the SE.  I guess that's what all comes down to?

[Webberweather53]

Hey Webber - What is +TNA mean?

 

 

As Buckeye fan showed , it essentially measures the SSTs in the eastern-deep tropical Atlantic, & this index is a close relative to the Atlantic Multidecadal Oscillation, as the two show an umsmoothed correlation of .769 (moderate-high), although the AMO relies on using the Kaplan SST that goes back dataset while the TNA uses Reynolds Optimum Interpolation/Hadley SSTs which can be a source for some of the relatively minor discrepancies between the two indices, but since the two are so closely related, correlations to 500mb, SST, temps, etc. can be used interchangeably between the two. Simply put, the TNA index primarily focuses on the tropical sector of the AMO...

 

 

 

What I thought was fairly amazing about the TNA index was how closely it matches up w/ the weak El Nino North American temperature composite, which says something about the relationship between the atlantic modes & the ENSO index (El Nino= +AMO/TNA spikes). And you wonder why the last few Atlantic Hurricane Seasons have been struggling, no El Nino in the last 4-5 years to spike the AMO. I could go further & explain the relationship between multi year warm ENSO events & rather destructive & active hurricane seasons in the cold multidecadal phase of the AMO, but I will save this for a later time...

 

The monthly winter temperature progression of these indices are also in compliance w/ my winter analogs. Relatively mild Dec nationwide, seasonable-cool East Coast, frigid January, then the core of the cold shifts southeastward in February..

[packbacker]

But that would most likely keep the cold to our north unfortunately (if it is right)

 

 

This does look good on the 12z GFS Ens

 

 

 

JB also said he thought the Euro-ENS wasn't right and that the trough would be further east.

[BullCityWx]

But that would most likely keep the cold to our north unfortunately (if it is right)

 

 

This does look good on the 12z GFS Ens

 

 

Any sort of SE ridge would be a deathnell to winter hopes south of I-20. Even here, you cant do much with any semblance of a ridge. 

[griteater]

I guess like some storms, it's a model war for the pattern too...If the GFS/GEFS is right, the PNA is positive with lower heights in the SE.  Then the SE ridge is not a problem.  If EURO is right PNA stays negative for a while longer causing heights to raise in the SE.  I guess that's what all comes down to?

 

Yes, it's really about the Alaska ridging and how it orients itself.  Euro Ens has it farther west and the troughing tucks underneath into the western U.S., whereas the GFS Ens is farther east with the Alaska ridge, and the troughing is east of the Rockies.

[EmersonGA]

Any sort of SE ridge would be a deathnell to winter hopes south of I-20. Even here, you cant do much with any semblance of a ridge. 

All it does is lead to depression after watching Little Rock and Memphis cash in over and over.  I will be sitting at 60 while 100 miles to my west they will have a raging icestorm.

[burgertime]

Yay, Euro has a big wrapped up storm which gives some backside snow to NC on Christmas Eve. Not likely to happen but fun none the less. 

[superjames1992]

LOL at the Euro.  I'm not sure I've ever seen a 980 mb LP crash over the Apps like that, ushering in that much cold air.  Seems to be a ridiculous wrapped-up solution.  Perhaps, the Euro is going crazy with over-amplifying again, per usual.

[LithiaWx]

PNA looks to go negative? Pretty sure I just saw that. Not good.

[metwannabe]

PNA looks to go negative? Pretty sure I just saw that. Not good.

Lol it's one model run......which by the way is 100% different from 00z

[DaculaWeather]

Michael Ventrice

@MJVentrice

GEFS likes the idea of high-latitude ridge development and the emergence of the -NAO late next week. Cold look for US pic.twitter.com/poelpKY6Cm

[packbacker]

PNA looks to go negative? Pretty sure I just saw that. Not good.

 

 

Lol it's one model run......which by the way is 100% different from 00z

 

 

Atleast the pattern is changing...LOL...

 

[LithiaWx]

Lol it's one model run......which by the way is 100% different from 00z

 

Looks like more than one model run :

 

[mackerel_sky]

Any sort of SE ridge would be a deathnell to winter hopes south of I-20. Even here, you cant do much with any semblance of a ridge.

Didn't the SE ridge keep showing up on models last year, but not actually verify!?

[burgertime]

Looks like more than one model run :

 

hY4LAbe.png

 

Having been in total model watching the last few days I'm not worried at all. I think a lot of this is from the LR breaking down the pattern like it usually does in the LR. We saw it last year and this year, pattern tends to be stubborn and stick around longer than models can predict. We saw that with the mild pattern change models were predicting. I think we'll end up with same here. Yes +PNA will break down eventually, but with the overall look it's not likely to be long term and should rebound quickly. The good thing is, that the +PNA can overcome the +NAO. With a -NAO and -AO the +PNA is not so important. We can't just focus on one of the indices we have to look at everything. Just my two cents. 

[burgertime]

Didn't the SE ridge keep showing up on models last year, but not actually verify!?

 

Much different pattern last year. 

[Webberweather53]

Atleast the pattern is changing...LOL...

 

 

 

In the long run, the -PNA will be necessary to pattern restoration & hopefully will result in a healthy swath of snow from the Rockies through the Midwest & Great Lakes... We have to solidify & fill in the snowpack over the northern tier if we have any intentions of *sustaining* a cold/snowy pattern in the southeast within the next several weeks, because having the southern edge of the snowpack getting pushed all the way up to near the Canadian Border & I-94 corridor simply won't cut it in most cases.

 

The faltering snowpack, especially over the eastern US, is a huge reason why this system next week will be primarily liquid instead of a robust winter storm, fresh snow like that w/ high albedo raises surface pressures in the PBL & increases the intensity ofcold air advection & CAD here in the Carolinas when all other ambient conditions are approximately equal...

[BullCityWx]

Euro ENS control showed that same pattern a few days ago

[DaculaWeather]

JB just posted this:

 

Notes and asides: This trough keeps getting deeper for Christmas over the east.

So when was the last time this kind of trough was on the east coast at Christmas?

There are only 3 I can find in the past 21 years

2002

1995

1993"

[packbacker]

In the long run, the -PNA will be necessary to pattern restoration & hopefully will result in a healthy swath of snow from the Rockies through the Midwest & Great Lakes... We have to solidify & fill in the snowpack over the northern tier if we have any intentions of *sustaining* a cold/snowy pattern in the southeast within the next several weeks, because having the southern edge of the snowpack getting pushed all the way up to near the Canadian Border & I-94 corridor simply won't cut it in most cases.

 

 

The faltering snowpack, especially over the eastern US, is a huge reason why this system next week will be primarily liquid instead of a robust winter storm, fresh snow like that w/ high albedo raises surface pressures in the PBL & increases the intensity ofcold air advection & CAD here in the Carolinas when all other ambient conditions are approximately equal...

 

That's interesting...this is what the EPS shows, sucks for us (SE) the next 2 weeks but if builds up the snowpack/cold over northern/central US/CN then it might be what is best for us come mid-Jan.  But that means it could be 4 weeks before we get into a favorable situation, assuming the EPS is correct.  If the GEFS is correct the snowpack could still build up with clippers I guess, as that is a better pattern for us in the 10-15 day period.  I don't know which one will be correct.

[SN_Lover]

NAO looks to finally go neutral/negative. Low south of Greenland looks to stay with the High West of Africa sliding south. Should provide more ridging East of the CONUS, and more stout trough over the SE. PDO looks to be getting more positive with cold and warm anomalies increasing in magnitude. AO even goes more negative toward the end of the GEFS run. GEFS was even gracious enough to give us a positive TNH pattern at the end of the run. BOTTOM LINE: THE END OF ABOVE AVERAGE TEMPS PATTERN FOR THE SE IS APPROACHING. 

[burgertime]

 

JB just posted this:

 

Notes and asides: This trough keeps getting deeper for Christmas over the east.

So when was the last time this kind of trough was on the east coast at Christmas?

There are only 3 I can find in the past 21 years

2002

1995

1993"

 

 

The big problem is that it's 200 hours away dealing with phasing and timing that is hard enough for models to get a handle on 84 hours out. It's interesting for sure but as depicted extremely unlikely.