Winter 2014-2015 Pattern Discussion Thread I

[packbacker]

Lol all the blocking is over central Canada. Doesn't the atmosphere know we had a near record high SAI??

 

Unfortunately not, LOL.  Going to be quite tenuous until we see a favorable pattern show up on the ensembles.  Since all the seasonal models are wrong with the warmth they show I am sure we have nothing to worry about....

[FallsLake]

Unfortunately not, LOL.  Going to be quite tenuous until we see a favorable pattern show up on the ensembles.  Since all the seasonal models are wrong with the warmth they show I am sure we have nothing to worry about....

If (and I mean if) this is just a short warm period before a colder more dominate winter pattern(around mid Dec), I am fine with what is happening. Even in cold patterns it is still hard to get winter storms this time of year. As I stated above the low level temps are not bad during this warm period. (As Pack said) Low to mid 50s with maybe near freezing lows will not kill the Christmas spirit. Then if we do flip around mid month that could give us a real potential around x-mas.  

[packbacker]

So that's what blocking (-AO, -NAO) looks like...lets see what the ensembles show in a few...

[griteater]

Euro at 240 not that bad.  PNA is actually maxed out on Allan's chart with troughing in the east.  AO looks a bit negative too.  Looking likely that we will see a sizable Aleutian Low develop, but ensembles want to creep it east into the Gulf of Alaska and move the W Canada ridging into central Canada, shutting off the cold air.

[packbacker]

Euro at 240 not that bad.  PNA is actually maxed out on Allan's chart with troughing in the east.  AO looks a bit negative too.  Looking likely that we will see a sizable Aleutian Low develop, but ensembles want to creep it east into the Gulf of Alaska and move the W Canada ridging into central Canada, shutting off the cold air.

 

Yeah, the pac needs some work but finally getting rid of the lower heights over Greenland is a welcome sign.  Granted, it's the 10 day Op, but it's a start.

[LithiaWx]

Euro at 240 not that bad. PNA is actually maxed out on Allan's chart with troughing in the east. AO looks a bit negative too. Looking likely that we will see a sizable Aleutian Low develop, but ensembles want to creep it east into the Gulf of Alaska and move the W Canada ridging into central Canada, shutting off the cold air.

Great post. I also see signs pointing to an above average chance at a favorable pattern developing or taking hold by mid month.

[LithiaWx]

Yeah, the pac needs some work but finally getting rid of the lower heights over Greenland is a welcome sign. Granted, it's the 10 day Op, but it's a start.

It's a start as you say but also not the only indicator pointing to a cold or at least not unfavorable pattern.

This imo could be everything setting up to give us exactly what a cold and snow lover wants to see living in the SE.

[LithiaWx]

Just my two cents but you really cannot trust the models 5+ days out. I remember in November people were going warm for the middle to the end of the month. I remember people posting maps of us torching at Thanksgiving. Look how that turned out. Pretty darn cold and we had 3-4 inches of snow on the ground. You would think people would not get caught up in the long range chase year after year but it never fails people look at the models 10+ days out and take it literal. Enjoy whatever is coming up. I am sure it will change as we head into the middle of December.

Great post, except for the torching t-day. Models had a great grasp on the cold shot we saw. They also had the extreme although short torch some of is saw right before t-day. Models also pointed to warmth after t-day which is exactly what is enroute. There seems to be this narrative that rthe models were wrong when they had the General idea pretty much pegged. If anything they were too cold as I was pegged to see sub zero 850s and we never got there.

[Cold Rain]

Euro at 240 not that bad. PNA is actually maxed out on Allan's chart with troughing in the east. AO looks a bit negative too. Looking likely that we will see a sizable Aleutian Low develop, but ensembles want to creep it east into the Gulf of Alaska and move the W Canada ridging into central Canada, shutting off the cold air.

It's a beaut, Clark, it's a beaut!

[Wow]

Euro at 240 not that bad.  PNA is actually maxed out on Allan's chart with troughing in the east.  AO looks a bit negative too.  Looking likely that we will see a sizable Aleutian Low develop, but ensembles want to creep it east into the Gulf of Alaska and move the W Canada ridging into central Canada, shutting off the cold air.

 

Extrapolating from there, It looks like a PV setting up over SE Canada with a split flow pattern developing out west.  I'll take it.

[griteater]

12z Euro Ensemble not very good.  It continues the strong El Nino look with expansive Aleutian Low anomalies in the Gulf of Alaska.  Ridging and warmth throughout southern Canada.  SE U.S. above normal temps through most of the 15 day run.

[Marion_NC_WX]

Great post, except for the torching t-day. Models had a great grasp on the cold shot we saw. They also had the extreme although short torch some of is saw right before t-day. Models also pointed to warmth after t-day which is exactly what is enroute. There seems to be this narrative that rthe models were wrong when they had the General idea pretty much pegged. If anything they were too cold as I was pegged to see sub zero 850s and we never got there.

 

 

I think you are mis-reading MET1985's comment...he's making reference to how the long range maps (days 8 and beyond) looked compared to what actually verified...hence the comment he made about how you can't trust anything beyond Day 5 right now.

I also remember back around Nov 15th that the global model 10-day maps were showing above normal heights across the Eastern 2/3rds of the US. People on here, Joe Bastardi and others were all wondering if the models were missing out....it wasn't until the week of Thanksgiving before the globals figured it out.

 

I personally think there's a chance the same thing is happening right now...what you see on Day 10,11,12 today may be vastly different than what actually occurs.

[metwannabe]

12z Euro Ensemble not very good. It continues the strong El Nino look with expansive Aleutian Low anomalies in the Gulf of Alaska. Ridging and warmth throughout southern Canada. SE U.S. above normal temps through most of the 15 day run.

Gfs and euro are worlds apart with the mjo therefore the models are 100% different

[packbacker]

"Houston...we have a problem"

This was posted in another thread, specifically read questions 18-19...forecast derailing, yikes.

http://www.vwkweb.nl/index.php?page=537&sl=1

[Cold Rain]

"Houston...we have a problem"

This was posted in another thread, specifically read questions 18-19...forecast derailing, yikes.

http://www.vwkweb.nl/index.php?page=537&sl=1

So:

A) You found another spec of cool water,

B ) The SAI was so good it was actually bad, or

C) We don't have any idea about pretty much anything when it comes to LR forecasting.

[LithiaWx]

"Houston...we have a problem"

This was posted in another thread, specifically read questions 18-19...forecast derailing, yikes. http://www.vwkweb.nl/index.php?page=537&sl=1

Question 17. What's your forecast of the winter 2014/15? Last year we saw lot's of cold in parts of the North America. What's your expectation of this year, will Europe and Asia get their share as well?

With the high values for both the SAI and SCE, I am expecting a negative AO this winter and our model forecast is consistent with the expectation of a negative AO winter. The forecast is posted on the NSF website:

http://www.nsf.gov/news/special_reports/autumnwinter/predicts.jsp

Cold air has become established in both North America and northern Eurasia conducive to Arctic outbreaks on both continents if the negative AO materializes this winter.

Question 18. This years SCE/SAI has been very high. According to your theory we can expect a negative (very) AO. How would you describe the developments after 31st of October? Is everything going according to plan ?

There are things that have transpired as I would expect since the end of October and some that have not. From the end of October through the third week of November, Eurasian snow cover stagnated for an unusually long period. Not sure what to make of it but it does give me pause. Also a persistent and deep polar low has developed in Northwestern Asia that is not typical of high snow cover years and I will discuss more about it in my answer to question 19.

Question 19. In your blog 14 November you wrote that the current atmospheric configuration is somewhat orthogonal to the mean atmospheric response to snow cover with the strengthening and expansion of the Siberian (high) different from composite analysis based on high minus low snow cover. We wonder in what way the current (14 November) configuration differ from the expected one and what might be the cause of that? Was the Siberian high in November in the right place for changing the Jetstream and for WAFz?

The deep polar low in Northwestern Asia that developed in November has interfered with the expansion of the Siberian high. The WAFz was active in November but I believe that it would have been even more active had the polar low not formed in that unusual location. That is what I was referring to when we wrote that the atmospheric response is orthogonal to high snow cover extent in the in blog dated November 14. In Cohen and Jones 2011 (on tropospheric precursors) and Cohen et al. 2014 (J. Climate) we provided plots of the atmospheric anomalies that are optimal for breaking down the stratospheric polar vortex and that are associated with high Eurasian snow cover. The models have been predicting that low to slide off to the south and east closer to its climatological position and more favorable for further expansion of the Siberian high as shown in the above mentioned papers. However today the models are predicting that the polar low will redevelop further west. I am watching this development very closely. If the low deepens in the location as the models predict and remains persistent that would destructively interfere with triggering further WAFz and weakening of the polar vortex, something more common with low snow cover extent.

Question 20. The United States and Canada experienced a massive cold outbreak in November. Lot's of snow e.g. in Buffalo. Was this outbreak related to SCE/SAI?

I would not say that the cold air outbreak in North America was forced by the high snow cover across Eurasia but was associated with it. The rapid advance of snow cover in November contributed to very cold temperatures in Siberia in October. So when the cold air mass in Siberia was dislodged and traveled over the Pole into North America it was unusually intense for this time of year. We posted on our Arctic Oscillation blog:

http://www.aer.com/science-research/climate-weather/arctic-oscillation

A temperature anomaly animation that was created by compositing high snow cover years minus low snow cover years from September through February. You can see in the animation a strong Arctic outbreak into North America in mid November. So I do think that a rapid advance of Eurasian October snow cover and an Arctic outbreak into the United States a couple of weeks later are related.

[Cold Rain]

Well Larry, we know what the AER model is now. Lol!

[pcbjr]

So:

A) You found another spec of cool water,

B ) The SAI was so good it was actually bad, or

C) We don't have any idea about pretty much anything when it comes to LR forecasting.

 

Pretty much "C)"

[LithiaWx]

What a fascinating read. Awesome find packbacker

[LithiaWx]

I think you are mis-reading MET1985's comment...he's making reference to how the long range maps (days 8 and beyond) looked compared to what actually verified...hence the comment he made about how you can't trust anything beyond Day 5 right now.

I also remember back around Nov 15th that the global model 10-day maps were showing above normal heights across the Eastern 2/3rds of the US. People on here, Joe Bastardi and others were all wondering if the models were missing out....it wasn't until the week of Thanksgiving before the globals figured it out.

I personally think there's a chance the same thing is happening right now...what you see on Day 10,11,12 today may be vastly different than what actually occurs.

I read his post just fine. My comments stand, the models have been pretty good in the medium-long range over the last two to three weeks. If you know how to read them the general idea of what was coming was clear.

[griteater]

Gfs and euro are worlds apart with the mjo therefore the models are 100% different

 

I think the GEFS probably has the better idea with the MJO signal continuing on into 7-8-1, but regardless, both the GEFS and the Euro ENS build the Aleutian Low then move the low anomalies east a bit into the Gulf of Alaska, with western N America ridging moving east as well (moreso on the Euro).  At any rate, seeing the Aleutian Low is good.  We'll have to see how the ridging to its east sets up, and how it evolves...and if any meaningful blocking shows up.

[Met1985]

I read his post just fine. My comments stand, the models have been pretty good in the medium-long range over the last two to three weeks. If you know how to read them the general idea of what was coming was clear.

For the record the models were showing a torch right around Thanksgiving about 8-10 days out. There was a map that someone posted showing most of the east being well above normal. But hey does not matter know. I disagree with the models doing well in the mid to long range. They have been all over the place. All I can say is that the models are going to vary from run to run and day to day especially with everything going on in the Northern Hemisphere.

[Met1985]

The map I was thinking about is in the Fall thread post number 2005 post from the parallel GFS 2m temps.

[valkhorn]

I hope a vlizzard comes an slaps half of ya in the fa e nothing but hypecrets members only club around heree!!!!!!

Who can argue with that? That's some authentic frontier gibberish

[packbacker]

So:

A) You found another spec of cool water,

B ) The SAI was so good it was actually bad, or

C) We don't have any idea about pretty much anything when it comes to LR forecasting.

 

 

What a fascinating read. Awesome find packbacker

 

That was very interesting, someone just posted it on the main board....it's not good when Cohen himself is concerned.  Considering every forecaster's winter outlook was based on a solid -AO due to the SCE/SAI this obviously isn't good.  Hopefully things normal out and the PV takes a beating by end of Dec.

 

Quote from Cohen in the article:

 I am watching this development very closely. If the low deepens in the location as the models predict and remains persistent that would destructively interfere with triggering further WAFz and weakening of the polar vortex, something more common with low snow cover extent.

[Cold Rain]

But, in Question17, he said he does expect a -AO. So that's good, I guess.

[franklin NCwx]

That was very interesting, someone just posted it on the main board....it's not good when Cohen himself is concerned. Considering every forecaster's winter outlook was based on a solid -AO due to the SCE/SAI this obviously isn't good. Hopefully things normal out and the PV takes a beating by end of Dec.

Quote from Cohen in the article:

I am watching this development very closely. If the low deepens in the location as the models predict and remains persistent that would destructively interfere with triggering further WAFz and weakening of the polar vortex, something more common with low snow cover extent.

The forecast from wxbell was not based on this. I don't think Joe Aleo has even mentioned it.

If anybody does not have access to wxbell you can see the Saturday summary for free every Saturday. JB shows their thoughts for Dec which we're they have had out for many weeks.

[Met1985]

This was posted by ginxy on the main board. Thought it was a good read. Is from Dr. Cohens blog.

http://www.aer.com/science-research/climate-weather/arctic-oscillation

[packbacker]

The forecast from wxbell was not based on this. I don't think Joe Aleo has even mentioned it.

If anybody does not have access to wxbell you can see the Saturday summary for free every Saturday. JB shows their thoughts for Dec which we're they have had out for many weeks.

 

I didn't know that, I didn't see his detailed thoughts that went out to this commercial customers, although I would be surprised if they didn't consider it.  

 

Let's see how WB's Dec forecast does, this is what they have for Dec...

 

light blue is -1 to -3F

darker blue is -3 to -5F

[packbacker]

This was posted by ginxy on the main board. Thought it was a good read. Is from Dr. Cohens blog.

http://www.aer.com/science-research/climate-weather/arctic-oscillation

 

A couple of things I took from that...if he is correct and there is a SSW in early January then things would get interesting in mid/late January.  Things could still be fine before then as GaWx pointed out the other day, we don't need a SSW but I would think we would still need atleast a weakened PV.

 

Hence, we see a lower probability of a SSW for December than anticipated in previous postings We anticipate that the polar low will eventually slide off to the south and east allowing for the Siberian High to expand and recommence vertical wave propagation.

 

We continue to anticipate that the vertical wave propagation will resume in mid- to late December and become anomalously strong, for reasons discussed above. This should result in a significant if not major SSW, consistent with the high October Eurasian snow cover paradigm. Therefore, the prospects for a SSW in early January are still highly probable