Winter 2014-2015 Pattern Discussion Thread I

[GaWx]

 I recently did a study of the dates of the 11 strong SSW's since 1979 and the MJO phase. Criteria: strong SSW based on a warming to an anomaly of +28+ as per this:

 

 http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/

 

I'm sure others would have different criteria/sources.

 

Dates in calendar order starting with Dec.: 7, 12, 17, 23, 23, 29, Jan: 1, 9, 14, 22; Feb.: 9

 

MJO phases for each SSW peak: 1, 3, 3, 4, 6, 6, 8, 8, 8; Also 2 COD (nearest to 2 and 5)

 

They have occurred about once every three years on average fwiw. So, not rare by any means.

[packbacker]

Latest EPS says what warmup for the SE. Has a presistent trough days 10+, below avg heights. Nice looking run.

[LithiaWx]

Long range models still have a crap look for the U.S. Russia continues to get their epic winter while the U.S. waits. The only glimmer I've seen so far is the Euro weeklies and some of the euro ensemble runs. SSW is a rabbit out of a hat imo. If we are hoping for that to change the pattern folks need to realize we could get a SSW event and the cold gets dumped on Siberia. I'm holding out for a pattern that gets Canada cold first then we have something to work with. A SSW event to me is just the cherry on top of a sundae.

[max100]

Winter started early, sure there is a break for a time, but this winter is going to be what we have been saying since spring. nasty

https://twitter.com/BigJoeBastardi

[griteater]

To my untrained eye, on the maps posted above,if the feature near Alaska would back up slightly, and the block over Greenland would form, the arctic would be unleashed on the central/ eastern half of the US!

 

Mack - if that were a 500mb plot, then yes, I would agree....but that's at 30mb way up in the stratosphere, so it's completely different and doesn't have those same effects.

[dan123]

Long range models still have a crap look for the U.S. Russia continues to get their epic winter while the U.S. waits. The only glimmer I've seen so far is the Euro weeklies and some of the euro ensemble runs. SSW is a rabbit out of a hat imo. If we are hoping for that to change the pattern folks need to realize we could get a SSW event and the cold gets dumped on Siberia. I'm holding out for a pattern that gets Canada cold first then we have something to work with. A SSW event to me is just the cherry on top of a sundae.

Didn't webberweather explain to you his reasoning as to why the pattern will get better towards xmas and especially the new year?

[LithiaWx]

Didn't webberweather explain to you his reasoning as to why the pattern will get better towards xmas and especially the new year?

Yes, although I'm not sure what that has to do with my post.

[franklin NCwx]

Latest EPS says what warmup for the SE. Has a presistent trough days 10+, below avg heights. Nice looking run.

yes sir they do! Lining up well with the gefs love the blocking over Canada.

[griteater]

Latest EPS says what warmup for the SE. Has a presistent trough days 10+, below avg heights. Nice looking run.

 

Pack - I'm viewing it as baby steps at this point.  Looks like a cooler pattern, but not a cold one.  Still a lot of zonal flow coming off the Pacific.  We wait.

[dan123]

Yes, although I'm not sure what that has to do with my post.

You said pattern looks like crap for the U.S but there are signs by D14-15 that the pattern starts to improve around that time

[LithiaWx]

You said pattern looks like crap for the U.S but there are signs by D14-15 that the pattern starts to improve around that time

Depends on who you ask and what models you look at. Today's indicators don't look good to me. I do like the euro weeklies and some of the recent EPS runs.

[jburns]

Didn't webberweather explain to you his reasoning as to why the pattern will get better towards xmas and especially the new year?

 

We all need to stop taking everything someone, anyone, says as gospel.  I haven't talked to Webber, but I think, and hope, he would agree that the word, "will" in your statement is a bit strong and there is room for other interpretations and opinions.  The pattern should get better, the pattern may get better, is about as strong as anyone without a time machine can go.  We need to stop taking everything as a direct challenge to something else.  In other words, relax.  We will know when the time comes.

[franklin NCwx]

Canadian ensembles getting there too. Lower heights over the Aleutians good pna ridging.

[Batman]

I am going to take a real simplistic approach to this post. This past week was dry and warm. Hit 70's IMBY a few times. It rained today and will likely struggle to get into the 50's most if not all of next week. A couple highs in the upper 40's not out of the question for MBY next week. LR shows more promise both locally and globally than it has in the last week or two. Maybe not a snowstorm coming from the gulf in the next 2 weeks, but I would categorize the above as a "better pattern". I realize that I live in the deep south. If I were angry every time there was not snow in my immediate forecast, I would be an angry person. I am very optimistic about the latter half of the month and the winter in general.

[GaWx]

Model consensus IMO has gotten much more progressive toward a new pattern since 24 hours ago. Also, even before that, the torching is limited with the next two weeks averaging not too far from normal. All in all, Dec. may turn out to average fairly close to normal if one assumes a chilly final few days. The Cohen analogs and 1939 are all ok with this scenario. I remain as pumped as ever about this winter's potential. With the recent modeled pattern change, I'm getting even more excited. Although I hope we get it since it can only help -AO prospects, I'd remain optimistic even if we turn out to not get a SSW. The SAI/OPI keeps me confident in a strong -AO, regardless. I'm still expecting a cold Jan-Feb with the reasonable chance at a relatively historic month of those two.

[LithiaWx]

Model consensus IMO has gotten much more progressive toward a new pattern since 24 hours ago. Also, even before that, the torching is limited with the next two weeks averaging not too far from normal. All in all, Dec. may turn out to average fairly close to normal if one assumes a chilly final few days. The Cohen analogs and 1939 are all ok with this scenario. I remain as pumped as ever about this winter's potential. With the recent modeled pattern change, I'm getting even more excited. Although I hope we get it since it can only help -AO prospects, I'd remain optimistic even if we turn out to not get a SSW. The SAI/OPI keeps me confident in a strong -AO, regardless. I'm still expecting a cold Jan-Feb with the reasonable chance at a relatively historic month of those two.

One thing I think most people can agree on is a new pattern taking hold late month. We certainly appear headed toward something different, my concern is if that differnt pattern is what we want or not. I don't know of a way to know that right now since the change is so relatively far off.

Great post as usual Gawx.

[metwannabe]

Model consensus IMO has gotten much more progressive toward a new pattern since 24 hours ago. Also, even before that, the torching is limited with the next two weeks averaging not too far from normal. All in all, Dec. may turn out to average fairly close to normal if one assumes a chilly final few days. The Cohen analogs and 1939 are all ok with this scenario. I remain as pumped as ever about this winter's potential. With the recent modeled pattern change, I'm getting even more excited. Although I hope we get it since it can only help -AO prospects, I'd remain optimistic even if we turn out to not get a SSW. The SAI/OPI keeps me confident in a strong -AO, regardless.

I agree 100% with your statement about a possible SSW. The obsession with SSW events have been hardcore over the past month. Do they help??? Of course they do IF everything lines up . They could screw us as well by dumping the cold out west. But I agree with you Larry a SSW event is NOT a must to have a cold winter and to average below normal for the winter.

[LithiaWx]

Brett Anderson's interpretation of the Euro weeklies. I've been hugging the weeklies for a while, even when they were warm and it was unpopular to do so. I think the model is amazing and a great window into the general pattern we can expect moving forward in the very long range.

This IS a positive sign to me and one that frankly makes me very optimistic about late month.

The last image is a beauty IMO. Indicates a pattern that would be more favorable to the U.S. and also could be the start of a transition to something blockbuster.

[packbacker]

Pack - I'm viewing it as baby steps at this point.  Looks like a cooler pattern, but not a cold one.  Still a lot of zonal flow coming off the Pacific.  We wait.

 

Agreed, baby steps...just commenting that we are not warm, except for a day here or there, just a cooler pattern for the SE.

 

Edit:  Also, the EPS has gotten a little cooler/colder each run as the 20th approaches.  Might not mean anything but a few days ago it seemed for certain that we were going to torch from the 10-20th.

 

Edit2:  Compare the EPS 0z run on 12/5 with the 12z run from today, same 5 day period, ending on the 20th, that's pretty good changes with 36 hours...

 

 

[packbacker]

Also, before someone puts words in my mouth, I am not saying it's going to snow or be a snowy/colder pattern on the 20th.  Just things are improving for the better, which the post above clearly shows.

[Bob Chill]

I'm not sure why there are so many posts about all the cold locked over in Russia and how that ruins our chances over here. Airmass temps don't really travel the globe. They cool and warm based on height and pressure patterns. Ocean temps certainly play a role as well depending on flow.

Looking at the gefs/eps runs shows the pattern favoring a buildup of cold air over nw and n central Canada. Not an arctic hound pattern but one that could easily supply the eastern half of the conus cold continental air. It's a big step away from where we are now. Even with what is an ugly height pattern, cold Canadian HP's are having no problem pushing into the conus. They're too shallow and not cold enough for our latitudes but that's looking more promising to change down the line each day that goes by.

[RONALD B]

I'm not sure why there are so many posts about all the cold locked over in Russia and how that ruins our chances over here. Airmass temps don't really travel the globe. They cool and warm based on height and pressure patterns. Ocean temps certainly play a role as well depending on flow.

Looking at the gefs/eps runs shows the pattern favoring a buildup of cold air over nw and n central Canada. Not an arctic hound pattern but one that could easily supply the eastern half of the conus cold continental air. It's a big step away from where we are now. Even with what is an ugly height pattern, cold Canadian HP's are having no problem pushing into the conus. They're too shallow and not cold enough for our latitudes but that's looking more promising to change down the line each day that goes by.

100 percent agree ! when the time gets closer the models will have a better handle on the new pattern change they tend too struggle long range .

[LithiaWx]

I'm not sure why there are so many posts about all the cold locked over in Russia and how that ruins our chances over here. Airmass temps don't really travel the globe. They cool and warm based on height and pressure patterns. Ocean temps certainly play a role as well depending on flow.

Looking at the gefs/eps runs shows the pattern favoring a buildup of cold air over nw and n central Canada. Not an arctic hound pattern but one that could easily supply the eastern half of the conus cold continental air. It's a big step away from where we are now. Even with what is an ugly height pattern, cold Canadian HP's are having no problem pushing into the conus. They're too shallow and not cold enough for our latitudes but that's looking more promising to change down the line each day that goes by.

The lower heights along with the polar vortex are in Russia. I have a hard time buying we can get a snowstorm in the SE with the 500mb pattern that keeps showing up in the LR.

[Webberweather53]

Webber,

Keep up the great work! Q: if we don't actually get a SSW, do you still think we'll end up with a strong -AO for much of the Jan-Feb period? Do you think a SSW is crucial or just helpful for this particular winter?

 

Thanks. Now, I should mention that since the satellite record only goes back to 1979, thus we're working with a very limited dataset & in general, a statistically significant & confident relationship between the variables may not be easily attained. Also keep in mind the stratosphere is not necessarily a cause of the pattern but merely a reflection of largely the background intraseasonal-interannual forcing (w/ some room for persistence on longer timescales), especially from the troposphere and you can throw some outside solar & QBO influence into the mix. However, as you'll see below, I don't think it's a huge loss whatsoever if we don't see a SSWE, (even though I'm definitely in favor of an event occurring within the next several weeks) after all, the robust +PDO/El Nino combination we currently have is one of the most favorable base states regardless of AO/NAO, etc. for the southeastern US...

 

Even if we don't see an event, we're still more than likely going to end up below normal temperature wise for the winter as a whole despite that December (as anticipated) was relatively mild/seasonable. In fact, looking at all the El Nino years w/ +PDO in Sept-Oct (1902-03, 1903-04, 1911-12, 1913-14, 1918-19, 1923-24, 1925-26, 1940-41, 1941-42, 1957-58, 1958-59, 1965-66, 1969-70, 1972-73, 1976-77, 1982-83, 1986-87, 1987-88, 1991-92, 1997-98, 2002-03, 2004-05, 2009-10) only 3 out of the 23 events (1991-1992, 1997-1998, & 2004-2005) were above normal in the southeastern US in both January & February using the 1895-2000 climatological base period. That equates to about 85-90% of +PDO El Nino years having at least January or February colder than normal, ~70% of those years (1902, 1904, 1912, 1924, 1941, 1942, 1958, 1966, 1970, 1973, 1977, 1983, 1987, 1988, 2003, 2010) were colder than normal in both January and February in the southeast. I like those odds...

 

It gets better, if you look at the El Ninos w/ +AO/+NAO broken down by month (of course El Ninos are already biased towards the negative end of the NAO/AO indices, (which is quite evident in seeing there are 5 or less El Ninos with a +AO in Feb & +NAO in Jan/Feb) you see that December & January as expected are warmer than normal, but amazingly, even with a +NAO &/or +AO, the February composite is still colder than normal, quite a testament to the strength of the ENSO forcing which often is fully capable, especially later in the winter, in overwhelming an unfavorable +AO/NAO signal...

 

All forcing mechanisms aren't necessarily created equally & you likely wouldn't know this tidbit about +AO/NAOs in an El Nino by simply looking at the US PSD temperature correlations for the NAO/AO, which both max out w/ a positive correlation of ~.5 to February temperatures in the southeast while NINO 3.4 & Tropical Pacific SST EOF only come to about .4 & .3 respectively. Superficially it seems temperatures should be above normal in such a pattern, but this is clearly not the case..

In general it's fairly difficult to get the NAO to go positive in January or February & the AO in Feb, & and even if the NAO/AO go positive, it doesnt prelude wintry wx, as was the case in February 1973 and 2003, w/ the massive president's day snowstorm in 2003 & the big one that crushed the southeast in 1973 during the 2nd week of February... The winter of 1972-73 featured a remarkable contrast in snowfall on the US eastern seaboard with many areas of the southeastern US that were the recipients of the big snowstorm in mid Febriary seeing a lot more snow than the big cities of the northeastern US, with at least Washington DC (.1 inch), Baltimore (1.2 inches), & New York City (2.8 inches) experiencing their least snowiest winters on record...

http://www.erh.noaa.gov/lwx/climate/bwi/bwisnow.txt

http://www.erh.noaa.gov/lwx/climate/dca/dcasnow.txt

http://www.erh.noaa.gov/okx/climate/records/monthseasonsnowfall.html

 

 

 

 

Now, looking at the AO/NAO indices and how they stack up, I found little-no correlation in the winter as a whole (that doesn't mean that one isn't there, and we know from observing events like Jan 2010 & December 1984 that a SSWE has the capability to strongly modulate the Northern Annular Mode for at least a few weeks or so at a time, and I would likely best describe the forcing from stratospheric warming similar to solar i.e. elusive, although not nearly to that extent.) There's no doubt we need perhaps a few more decades of data at the very least before serious research can be undertaken. What surprised me a bit was that El Ninos without a stratospheric warming event actually had a lower overall seasonal AO.. It's clear to me in looking over the data which I've shown below, it's not impossible to see a month or two w/ a huge -AO even though we don't see a big warming event, this is evident in January 1979, 1998, February 1988, & March 1980... 

 

+ENSO Years AO w/o a SSWE

 

 

The same can be said for warm ENSO years, there were quite a few positive months in this regime, in fact, take the winter of 2002-03 for example, we had a decent SSWE in January, which didn't do much, if anything to the AO...

 

 

+ENSO Years AO w/ a SSWE 

 

 

Now here's the NAO data...

 

+ENSoO yrs w/o a SSWE, 1979-80 (one of the warm neutral-weak hybrid El Nino analogs) looks to do perfectly fine without a stratospheric warming event.

 

 

+ENSO yrs w/ a SSWE

 

Levi Cowan also made a very nice video a few years ago in the winter of 2011-12 during what even I would willingly quantify as a blowtorch about stratospheric warming events & ENSO. It's not difficult @ all to get cold into the eastern US following a SSWE in an El Nino, La Ninas on the other hand as he mentions, w/ help from the cold PDO, often resist cold from a SSWE, but there are exceptions like 1984-85 & 1998-99...

http://www.tropicaltidbits.com/blog/2012/01/05/notes-on-the-upcoming-stratospheric-warming/

 

 

On a side note, these Warm ENSO Neutral-Weak Hybrid El Nino years have been pretty much on target over the past 2 months, although just by viewing the 500mb for Oct & Nov, our AO looks like it will end up similar to or perhaps even lower than these years, which were in their own right quite a bit of fun...

 

[Webberweather53]

I'm not sure why there are so many posts about all the cold locked over in Russia and how that ruins our chances over here. Airmass temps don't really travel the globe. They cool and warm based on height and pressure patterns. Ocean temps certainly play a role as well depending on flow.

Looking at the gefs/eps runs shows the pattern favoring a buildup of cold air over nw and n central Canada. Not an arctic hound pattern but one that could easily supply the eastern half of the conus cold continental air. It's a big step away from where we are now. Even with what is an ugly height pattern, cold Canadian HP's are having no problem pushing into the conus. They're too shallow and not cold enough for our latitudes but that's looking more promising to change down the line each day that goes by.

 

The lower heights along with the polar vortex are in Russia. I have a hard time buying we can get a snowstorm in the SE with the 500mb pattern that keeps showing up in the LR.

 

 

You have to build the cold up into Eurasia before (& if) you have intentions of sending it across the arctic into North America, which usually doesn't happen until January anyway in years w/ a high northern hemisphere snowpack

[Bob Chill]

You have to build the cold up into Eurasia before (& if) you have intentions of sending it across the arctic into North America, which usually doesn't happen until January anyway in years w/ a high northern hemisphere snowpack

Agreed. But we don't need cross polar/arctic air for snow. I know you know this. Iirc- it was way colder in Eurasia than north america in 09-10.

I'm not sure what I'm arguing with Marietta either. I never said it was a good 500mb.pattern for snow. I said it was a good one to build and deliver bn air masses into the conus. If the Atlantic starts cooperating then it would look much better for snow chances. Even if it doesn't, the stj looks to remain active. We could all take our chances with a period of +pna/-epo and active southern stream. Nickel and dime events are much more common than big organized ones in any winte. I'd be happy with anything during Dec.

[LithiaWx]

Agreed. But we don't need cross polar/arctic air for snow. I know you know this. Iirc- it was way colder in Eurasia than north america in 09-10.

I'm not sure what I'm arguing with Marietta either. I never said it was a good 500mb.pattern for snow. I said it was a good one to build and deliver bn air masses into the conus. If the Atlantic starts cooperating then it would look much better for snow chances. Even if it doesn't, the stj looks to remain active. We could all take our chances with a period of +pna/-epo and active southern stream. Nickel and dime events are much more common than big organized ones in any winte. I'd be happy with anything during Dec.

Putting lipstick on a pig doesn't change the fact that it's still a pig. Unless we get a colder 500mb pattern on this side of the globe big sections of the SE have a near zero percent chance at snow. What does it matter if we get closer to a snow pattern but are still missing key pieces that would make a storm of significance possible?

[packbacker]

Agreed. But we don't need cross polar/arctic air for snow. I know you know this. Iirc- it was way colder in Eurasia than north america in 09-10.

I'm not sure what I'm arguing with Marietta either. I never said it was a good 500mb.pattern for snow. I said it was a good one to build and deliver bn air masses into the conus. If the Atlantic starts cooperating then it would look much better for snow chances. Even if it doesn't, the stj looks to remain active. We could all take our chances with a period of +pna/-epo and active southern stream. Nickel and dime events are much more common than big organized ones in any winte. I'd be happy with anything during Dec.

Agreed....and don't bother arguing with him, pointless.

[WxBlue]

Putting lipstick on a pig doesn't change the fact that it's still a pig. Unless we get a colder 500mb pattern on this side of the globe big sections of the SE have a near zero percent chance at snow. What does it matter if we get closer to a snow pattern but are still missing key pieces that would make a storm of significance possible?

 

Are you not listening? They're trying to tell you things look good for favorable 500mb pattern to return to this side of globe by late December.

[burgertime]

Putting lipstick on a pig doesn't change the fact that it's still a pig. Unless we get a colder 500mb pattern on this side of the globe big sections of the SE have a near zero percent chance at snow. What does it matter if we get closer to a snow pattern but are still missing key pieces that would make a storm of significance possible?

 

In his defense he did say he was looking for nickel and dime events...I wouldn't call those storms of "significance". Also due to the geography of where he is located...and granted a few on here there would be a chance in say NC with a +PNA/-EPO. Probably not points south such as GA or SC. Also the closer we get to a snow pattern aloft the better...just my two cents.