Winter 2012/13 wx discussion

I guess TWC decided not to name storms this year? Cause the one in California dumping feet of snow seems worthy to be named if they are.. I guess they will only name the smaller ones? Idk guess we will find out later in the month.

With all this warmth/energy one has to wonder if there in fact is not some severe wx awaiting us when the pattern changes to that of a colder one around the 12th of this month.

yeah no doubt toot... been watching this last 2 days with the models... going to hold off after the 0z runs tonite for i dig into this and comment

18z ensembles were excellent looking 192 and beyond. More and more confident that were gonna start seeing some cold and snow chances beyond the 12th of December.

Here's my quick synopsis after looking at all of todays guidance

The weather will start to get more interesting with possibly two significant storm systems affecting the eastern united states over the next couple of weeks. The first one (Dec 10-13th) will be the pattern changer and it could pack quite the punch with widespread severe weather possible ahead of a strong cold front.

This system also looks to produce snow in alot of the OH valley and great lakes regions. After this cold front sweeps across the eastern united states it will set the stage for a pure southern stream system in the Dec 15th-20th timeframe with a cold airmass and possibly blocking already in place allowing for a widespread winter event across a rather large chunk of the eastern US.

The North Atlantic Oscillation is how we measure this blocking and the graph below supports this winter event.. but its just one of many pieces that will need to fall into place to allow for this system. Its still a long ways out and many things can and will change.

12z GFS ensembles have some seriously impressive solutions towards the end of the week...

andyhb wrote:12z GFS ensembles have some seriously impressive solutions towards the end of the week...

Looks like severe outbreak to snowstorm for some on a few of those

Sure does. What that tells me, is the pattern is in the process of changing. How long it takes to fully change remains to be seen, but I think it will. Maybe it will change to a wintry look for us and last as long as the current regime has. Wouldn't that be awesome!

Jed33 wrote:Sure does. What that tells me, is the pattern is in the process of changing. How long it takes to fully change remains to be seen, but I think it will. Maybe it will change to a wintry look for us and last as long as the current regime has. Wouldn't that be awesome!

What current regime are you talking about? We've been below normal since August.

A few of the 18z ensembles trended southward with the system early next week. This would bring the dynamics and wrap around precip much closer to the state!

Guys, the pattern has changed, esp into the pacific, but the ridge is too far west, hence a trough to our west, allowing GLC's for a while. Until we either get ridging more east and or a -nao thats west based, it will be difficult to see any sustained colderwx for us. We should get those transient colder shots, but nothing long lasting. The trough being that far west allows for more of the dreaded southeast ridge over cuba. If im incorrect guys, please explain why im not.

I was mainly referring to the precip pattern as of post Sandy, I.e. November has been so dry, and the overall global circulation patterns that have been so unfavorable for us. I should have been more specific in my post. That was my fault. I shouldn't try to post while cooking supper, lol

Mrgolf wrote:Guys, the pattern has changed, esp into the pacific, but the ridge is too far west, hence a trough to our west, allowing GLC's for a while. Until we either get ridging more east and or a -nao thats west based, it will be difficult to see any sustained colderwx for us. We should get those transient colder shots, but nothing long lasting. The trough being that far west allows for more of the dreaded southeast ridge over cuba. If im incorrect guys, please explain why im not.

Did you miss the charts of the NAO going negative that I posted above? NAO blocking is agreed on by the ensembles into the extended range. This is due to the AO going deeply negative the last couple of weeks. The Arctic Oscillation is now progged to go even deeper than its last spike into negative territory!!

The AO is the root driver of a cold weather pattern in the lower latitudes. The last negative AO spike (which is basically a signal of the breaking down of the PV) is more or less what is responsible for the current pattern change.

This next spike into negative territory will just reinforce the cold and active weather pattern the second half of December and on into January! High latitude blocking is gonna be around this winter and this will argue for more sustained cold/trough over the eastern US. Ive been talking about the high chances of a negative AO winter since late summer/early fall with the correlations and such. Its good to see these correlations finally working out!

Clustered agreement between -4 and -5

Toot - we all know the nao is negative, but an east based block causes the trough axis to be favorable for the northeast, not so much for us. If the AO actually does get to a -5 or 6, then where the nao block sets up will be irrelevant, as there will be ridiculous cold coming down.

I personally like the end of the last few euro runs... Looks like its setting up a beastly arctic outbreak to me. Decent PAC ridging, cold front plowing through western Canada, energy in the southwest, and remnants of the coming cold front still hanging around.

Im just speaking in terms of temperature above..I agree.. east based is not that favorable for snow here in TN and im not sure what orientation the NAO will take on (East.. Neutral or West) but any of them still denotes a colder than normal pattern with us under mean troughing during winter.

IMO..the pattern looks to be more of a sustained cold wx pattern the second half of December into the first half of January. Nothing really screams brutally cold to me though.. hence the mixed or neutral signals in the eastern Pacific region EPO/PNA. That said..and contrary to popular belief we can still get hammered in a neutral or negative PNA regime!

Case and point... the infamous 2009/2010 winter with December and Febuary both having neutral PNA values. The next winter (2010/2011) December featured a negative PNA at -1.78 and we all know how Christmas timeframe turned out in the east! Whether we get a good subtropical jet/split flow pattern going for nice storm systems remains to be seen..but colder than normal has been signaled for a while now.

Question. Why does the GFS/Euro ensemble NAO graph differ so much from the CPC ensemble graph?

snowdog wrote:Question. Why does the GFS/Euro ensemble NAO graph differ so much from the CPC ensemble graph?

Im not sure which graph you are referring to when you say GFS/Euro ensemble NAO?

Just to give an idea on how important the December AO is for winter weather.. here are the December values from the last three winters.

December 2009 -3.413...Turned out to be a very cold winter

December 2010 -2.631 Turned out to be a very cold winter

Last December +2.221 The winter went on to torch

If the ensembles are correct this December AO value will end up averaging negative!

Toot wrote:

snowdog wrote:Question. Why does the GFS/Euro ensemble NAO graph differ so much from the CPC ensemble graph?

Im not sure which graph you are referring to when you say GFS/Euro ensemble NAO?

Raleigh's site...

http://raleighwx.americanwx.com/models/00zlinegraphs.html

vs

CPC NAO Spaghetti plot

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

brett anderson just posted his latest euro long range. goes through pretty much whole month of december... saying the end of month showing some blocking signals ove greenland finally... but also showing alaska staying cold also,which argues cold over the eatern us... he just doent think the bruntof the artic air will never get down into the lower 48... saying it stays bottled up in canada pretty much this month

After looking at the last 3 runs of the OP GFS (0,6,12), Euro, and long tele's on the ensembles, I'm not getting the excitement some of you are. There isn't enough amplification in the pattern to bring the cold air south. There are however plenty of chances for severe it seems. In his latest blog, Allan Huffman doesn't seem too excited either. +EPO/-PNA in a -PDO regime just isn't conducive for fun winter weather times in the Southeast. The Pacific pattern has to change to get a good pattern going. Hopefully towards the end of December early January?

tennessee storm09 wrote:brett anderson just posted his latest euro long range. goes through pretty much whole month of december... saying the end of month showing some blocking signals ove greenland finally... but also showing alaska staying cold also,which argues cold over the eatern us... he just doent think the bruntof the artic air will never get down into the lower 48... saying it stays bottled up in canada pretty much this month

I'd say he is more right than he is wrong. Just posted about the same take while you were posting this.

snowdog wrote:After looking at the last 3 runs of the OP GFS (0,6,12), Euro, and long tele's on the ensembles, I'm not getting the excitement some of you are. There isn't enough amplification in the pattern to bring the cold air south. There are however plenty of chances for severe it seems. In his latest blog, Allan Huffman doesn't seem too excited either. +EPO/-PNA in a -PDO regime just isn't conducive for fun winter weather times in the Southeast. The Pacific pattern has to change to get a good pattern going. Hopefully towards the end of December early January?

excellent post snowdog... i agree 100 percent

Well crap I wake up and winters canceled.. I guess we got another year like last year.. I cant believe this crap... If models still showing same warmth by January then we might as well atleast start to expect another last year cause all last year we was saying maybe it will change next week and we kept doing that and it never did change.

skillsweather wrote:Well crap I wake up and winters canceled.. I guess we got another year like last year.. I cant believe this crap... If models still showing same warmth by January then we might as well atleast start to expect another last year cause all last year we was saying maybe it will change next week and we kept doing that and it never did change.

LOLWUT? Just barely broken the seal on meteorological winter and ALREADY you're declaring winter cancel? Simma' down now......