Winter 2017-18 Disco

[showmethesnow]

Had spent a few hours the other day looking at NAO states for the first half of winter from years past and had meant to break it down and do a more detailed write up on it but never found the time. With me leaving on vacation tomorrow it doesn't look as if I will. So I thought I would throw a couple of quick observations out there. 

Since 1950 I found that a November -NAO (-.5 or greater) during a Nina (-.5 or greater) featured at least a trace of snow in 6 out of 9 months (3 trace, .5, 1, 2.0) for November and all 9 months in December saw snow (T, .4, .5, 1.2, 1.3, 2.3, 2.5, 6.3, 8.3). 

A neutral November NAO (-.5-.5) featured at least a trace of snow in 7 out of 10 years. (5 trace, .5, 1). December saw all 10 years with snow (2 trace, .1, .4, .6, .7, .8, .9, 4.8, 6).

A positive November Nao was only seen 2 months. Both months featured no snow in November and a trace and .2 inches in December.

Not etched in stone but generally speaking our best outcomes for November and December snowfall, irregardless of NAO state, feature higher heights in November to the east/southeast of Greenland, whether on its own or in conjunction with higher heights to the west even into central Canada. In fact looking at the better Nina winters (15 inches or greater) saw 6 out of 6 winters (17.1, 18.6, 19.1, 19.6, 26.1, 62.5), irregardless of the NAO state during November, have this feature. Didn't look to hard into the reason for this (only pulled up a handful of years) but have to speculate that is because the higher heights progress westward through the course of the winter into the prime western based -NAO region.

I found that the neutral NAO values on the graph can be very misleading as every one (10 years) featured some form of blocking around Greenland whether somewhat weak or riding on the edges of the NAO domain. In fact, of the 21 years that featured a Nina, irregardless of NAO, only one had no blocking and that was in 2011. 

A -NAO value in November favors a -NAO in December, 5 years (3 neutrals, 1 pos). December also finds 7 out of 9 of those years with some form of blocking, 1 that is marginal and one with none.

A neutral NAO in November on the other hand almost always features a follow up neutral in December (9 out of 10 years, 1 very weak + of .55). Half of the years have some form of blocking showing up.

Taking 95/96 out of the mix there was very little difference on total winter snowfall between a -NAO and a neutral NAO in November. With only 2 examples of a positive NAO during November, polar opposites of each other (1.8 vs 26.1) it is hard to speculate on it.

In summary, I think our best chances for the coming winter season for the first part (November, December) and as a whole, is to see higher heights to the east/southeast of Greenland (on its own or in conjunction with other blocking) in November and with a -NAO value for November as well. 

[Eskimo Joe]

Maybe we'll get lucky this year and see a nice Miller A for Christmas.  Nothing crazy, just a 5" - 8" event of wet snow that covers everything and gives that Burl Ives feel.

[Cobalt]

1 hour ago, Eskimo Joe said:

Maybe we'll get lucky this year and see a nice Miller A for Christmas.  Nothing crazy, just a 5" - 8" event of wet snow that covers everything and gives that Burl Ives feel.

You're giving me the feels man. All we need is some snow during December, and I'm happy

[Jebman]

On 10/17/2017 at 11:19 PM, 40/70 Benchmark said:

Considering the state of the ssts in that region last summer, it probably means something.

I think we'll get some blocking.

Copy that. 

Get those shovels ready!

You got to be optimistic. Otherwise, the Panic Room is gonna be jumpin'.

I never panic. I KNOW where I live: In a SNOWTOWN! 

[BTRWx]

This will be near banter-like, but one can't resist the potential from the latest CIPS Analogs that have October 1995 all over the top correlations for multiple upper level variables and multiple hourly frames!

[showmethesnow]

First time I have had a chance to look over the models in the last few days. Just some thoughts on what the models are showing as far as any possible pattern setting up.

As we head into November, a typical Enso driven pattern would normally be emerging for what we can expect for at least the first half of winter. And yet there is no clear signal nor does there look to be one in the next 2 weeks and possibly beyond if the models are correct. If anything the look as become even more chaotic.

In a typical Nina winter we would expect to see a strong steady state PAC jet impacting the Northwest US/Southwest Canada and yet that is not what the models see for the foreseeable future. We are seeing huge disturbances of the PAC jet in the central Pacific (and that looks to continue beyond day 15/16 as well) which are creating chaos downstream. What we are seeing on the models downstream of these disturbances are huge undulations of the PAC jet with it quite often resulting in it migrating farther north into Alaska and North western Canada, in essence forming a polar jet, that then is diving deep into the central US. We are also seeing what looks to be a somewhat active southern jet emerging on the models. An active southern jet comprised of both disturbance induced splits of the PAC jet as as well as that of the subtropical jet.

The pattern is chaotic but if forced I would probably say it is closer to that of a Nino, then a Nina or Neutral but even that is probably a stretch. Looking at the temp and precip anomalies the next two weeks do not offer much clarity as well except for the fact they are NOT what you would expect to see if a La Nina pattern were setting up for the winter. They are more suggestive of a cross between a weak Nino and Enso Neutral more then anything else. Maybe by mid to late November a ENSO driven pattern may emerge but it doesn't look if one will emerge in the foreseeable future.

All in all, I really like where we sit so far leading into what was supposed to be a Nina driven winter.

[AfewUniversesBelowNormal]

-NAO seems to be solid lock, 75-80% I'd say

[WxUSAF]

1 hour ago, StormchaserChuck said:

-NAO seems to be solid lock, 75-80% I'd say

Negative averaged over all of DJF?

[BTRWx]

33 minutes ago, WxUSAF said:

Negative averaged over all of DJF?

The 1995-1996 -NAO is crystal clear now, but what could have caused it?!

[uncle W]

the nao went negative on 10/22/95 except for one day on 12/2 and stayed negative until a day after the blizzard of 96...after that it was up and down for the nao with a 11 days of positive values in January...February had more days with a positive nao than negative...

ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii

the ao went negative from 10/28 and stayed mostly negative except for the second half of February...

ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii

it will be hard for that to happen again this year...the nao is negative now but the long range nao/ao spaghetti  forecast looks like a Tesler electric tower...

[AfewUniversesBelowNormal]

1 hour ago, WxUSAF said:

Negative averaged over all of DJF?

I think so. Not much stratospheric help though, so it could be weak negative majority of the Winter. 75-80% chance that DJF averages negative. 

[raindancewx]

On 10/18/2017 at 11:22 AM, Bob Chill said:

The aluetian ridge is doing some dirtywork in the npac. -PDO signature showing up. I sorta expect a -pdo during a nina but they're usually not a good sign for winter in the east in the MA. I expect some reversal of the SSTA structure through the end of the month if the aluetian trough/goa ridge sets up but I pretty much expect the aluetian ridge to return in Nov. 

 

Nina is still looking pretty weak in general. 

You are into visual checks right? This is what my analog system (for winter) has for October v. current conditions. I couldn't really get the pattern for winter using just La Nina, you need some cold-Neutrals in there too. You have to imagine an extra 0.1C of warmth everywhere given the analogs are centered on 1979, but are mostly warm AMO years.

[BTRWx]

1 hour ago, raindancewx said:

You are into visual checks right? This is what my analog system (for winter) has for October v. current conditions. I couldn't really get the pattern for winter using just La Nina, you need some cold-Neutrals in there too. You have to imagine an extra 0.1C of warmth everywhere given the analogs are centered on 1979, but are mostly warm AMO years.

Wow!  Excellent work there and thanks for sharing!  Is there anything you would be willing to share with us about how you came up with that without giving away the actual years?

eta: I see your discussion in the forecasting and discussion thread.

[Daniel Boone]

4 hours ago, StormchaserChuck said:

I think so. Not much stratospheric help though, so it could be weak negative majority of the Winter. 75-80% chance that DJF averages negative. 

Good work you do Chuck! Providing the nina doesn't somehow get a dose of roids and shove any blocking out, I think it's looking the best in the nao department than it has in years.

[AfewUniversesBelowNormal]

12 hours ago, Daniel Boone said:

Good work you do Chuck! Providing the nina doesn't somehow get a dose of roids and shove any blocking out, I think it's looking the best in the nao department than it has in years.

I think it works to advantage that the Nina is having trouble getting Strong. It will likely stay this way, maybe from the reverse perspective this is -NAO tendency winning out, B->A

[Bob Chill]

16 hours ago, raindancewx said:

You are into visual checks right? This is what my analog system (for winter) has for October v. current conditions. I couldn't really get the pattern for winter using just La Nina, you need some cold-Neutrals in there too. You have to imagine an extra 0.1C of warmth everywhere given the analogs are centered on 1979, but are mostly warm AMO years.

 

Looks pretty good. Current and analog SSTA plots make it a pretty easy call for our area. Below normal snowfall is the front runner by a good margin. Temps are more difficult because years with blocking have some solid cold periods and years that don't are pretty lame. 

My thoughts on winter here are pretty simple. 50-75% climo snow with volatile temps. One or 2 snow events can easily change our winter from pretty lame to acceptable. You can never rule out a fluke event or 2. Drawing an inside straight can make all the difference for decent snow totals. On the other hand, a couple good solid busts can swing it the other way.  

Temps will probably end up AN for DJF when it's all said and done but that won't be without some acceptable cold spells. Best chance at BN temps will prob be DJ. Other than the obvious (no blocking), we could suffer from periods of a -PNA. Especially if the -PDO continues to build over the coming months. That's always a pretty good clue that the pac might not cooperate. 

[AfewUniversesBelowNormal]

Really nice pattern coming up on models. Has that 95-96 feel. 

 

[mitchnick]

2 minutes ago, Bob Chill said:

Looks pretty good. Current and analog SSTA plots make it a pretty easy call for our area. Below normal snowfall is the front runner by a good margin. Temps are more difficult because years with blocking have some solid cold periods and years that don't are pretty lame. 

My thoughts on winter here are pretty simple. 50-75% climo snow with volatile temps. One or 2 snow events can easily change our winter from pretty lame to acceptable. You can never rule out a fluke event or 2. Drawing an inside straight can make all the difference for decent snow totals. On the other hand, a couple good solid busts can swing it the other way.  

Temps will probably end up AN for DJF when it's all said and done but that won't be without some acceptable cold spells. Best chance at BN temps will prob be DJ. Other than the obvious (no blocking), we could suffer from periods of a -PNA. Especially if the -PDO continues to build over the coming months. That's always a pretty good clue that the pac might not cooperate. 

Agree with you on the temps for the winter Bob, but for maybe the first time since after the 1/16 blizzard,  I'm a little more bullish on snowfall.  At least at BWI, my wag is 75%-125%. Like 2/15 & 3/15, I expect to see snow on SE winds often this year, but not as much accumulations with them.

[AfewUniversesBelowNormal]

La Nina having problems getting strong is a big hit on the Winter south wind theory. This time of the year, and minute differences, are important because It's pattern loading time happening now, and the La Nina is not getting established. 45N-60N actually seems to be the dominant energy. 

[Bob Chill]

4 minutes ago, mitchnick said:

Agree with you on the temps for the winter Bob, but for maybe the first time since after the 1/16 blizzard,  I'm a little more bullish on snowfall.  At least at BWI, my wag is 75%-125%. Like 2/15 & 3/15, I expect to see snow on SE winds often this year, but not as much accumulations with them.

Yea, I don't like long lead snowfall calls in our area. The combo of modest climo + the fact that we can get a big storm in almost any winter makes it hard. Choas is inherently unpredictable. lol

We're still a month away from understanding what Dec might look like in the high latitudes. If we kick off met winter with a -AO then your snowfall call is prob solid. 

[BTRWx]

If this nino-like atmosphere continues along with the weak nina, I like our chances!  That connection to the subtropics that continues to be modeled is definitely giving me a more bullish feel now.

[WinterWxLuvr]

I think a better measure of winter temps would be the median high and low.  It's awfully easy to get an outlier high temp that skews the average.

I'm amazed that in this technological age that we still use hourly readings of temperature (highs and lows) to determine the average temperature of a day.  The technology exists to collect data virtually every second and use it to determine the average temperature of a day.

Anyway, I agree that slightly above normal temps is a good call, and that snowfall is too variable to predict accurately.  I still feel somewhat good about the upcoming winter.

[showmethesnow]

I know I have been pounding on the PAC jet the last week or two but I really think it will be key with our winter. As many already know, and the reasons why, a typical Nina winter is normally bad for our winter chances here in the mid-Atlantic. It features a bad PAC setup and strong jet that quite often overrides other signals that may be a positive for our winter chances. But the last couple of weeks suggest we are dealing with anything but a typical Nina.

Besides what I have discussed previously about the disruptions to the jet (both recently and for the foreseeable future) which weaken it and create a very erratic jet there is one other thing that has fairly recently begun to become a prominent feature. And that is that we are now seeing large intrusions northward of the jet. What this northward progression of the jet is doing is infusing heat into the higher latitudes (polar regions). With this influx of heat we also see an associated rise of heights and as many know this quite often equates to high latitude blocking. This high latitude blocking is what we want to see for our winter chances. Now below I have some examples from the 00Z op run of the GFS.

 

Here at 78 hr we see a large buckling of the jet that gets fairly far north that is centered on central Canada. One thing not shown is the higher heights and significant ridging associated with it in western Canada. One other feature I want to point out is that we see a southern jet through Mexico and the Gulf.

 

Now at 144 we once again see the jet moving northward. Notice that wee see a farther progression northward as well as westward compared to the previous one. Not shown is that the higher heights have also shifted northward as well as westward where they are now centered on the Alaskan/Canadian border. Of note again notice we once again see a southern jet popping up through Mexico and the Gulf.

 

Now look at the 3rd intrusion northward at 186 hour. This is massive intrusion much farther northward then the other two once again centered farther westward over the Bering straits. Not shown but this is sending heat, higher heights and ridging all the way to the pole. Now once again notice to the south. Not only are we seeing a southern jet, we are also seeing a mid latitude jet as well as a polar jet. That's 3 jets running through the CONUS.

 

Now at hour 288 we are seeing the 4th jet intrusion northward in 12 days. This has shifted back to the east where it is centered close to what we saw at hour 78. But notice that is much farther north then the initial wave seen at hour 78. Not shown is that the higher heights and ridging have shifted back eastward somewhat and continue to extend to the pole. Now once again look to the south. We are seeing a southern jet as well as a mid latitude jet. Not to mention we will have the polar jet dropping into the CONUS shortly. 

 

Now at hour 384 we are seeing the beginning of another wave forming that should eventually move northward as the other waves have done. This wave looks to be westward of

hour 288 and looks to intrude just as far north. I think the reason we may be seeing these farther north intrusions now are because the initial 3 waves have done the dirty work of scouring out the lower heights around the pole leaving easier access for followup waves. And once again we see 3 jets. A polar, mid latitude and a southern.

 

 

 

Now this constant influx of heat to the pole is having an effect on the PV in the stratosphere as well (50, 30, 10 mb). As below you can see the initial state of the PV where it is located just on the other side of the pole (blue circle). Notice the higher heights (red circle) is located over central Canada and corresponds to where the initial warm air intrusions have occurred.

 

Now look at day 9. Notice we have seen a shifting of the higher heights (red circle) to the north and west in conjunction with the westward progression of warm air intrusions. In response we see a slight shifting of the PV down and to the right.

 

Now at day 16 we have a very obvious response from the PV from the constant barrage of warm air intrusions. We see a significant shift, bringing the PV onto our side of the globe into northern Greenland. Now besides the obvious benefit of bringing the pv to our side of the globe is the one thing that the smoothing of the ensembles does not show. These warm air intrusions are wrecking havoc on the pv as well. They are weakening it and contorting it's shape, basically making it dance  a jig. All very good things in regards to not allowing it to strengthen and wreck havoc on our winter chances.

 

Couple of thoughts on the above. Looking over the 16 days I have to wonder if the model may be suggesting what the possible winter pattern in the Pacific may be (barring any midwinter pattern change of course). Jet induced warm air intrusions (centered western Canada to the Bering straits) initially to the east progressing westward only to return back to the east to begin the process once again. If this is in fact the case this cycle would suggest stable great high latitude blocking. Also of note was the subtropical/southern jet continues to pop up as we have seen for the last couple of weeks. But what is even more significant is that this feature is becoming more pronounced on the models as we progress closer to winter. All I can say about that is, 'Hot Damn'. Final thought. 3 jet streams in the CONUS at once (polar, mid latitude, southern)? SIGN ME UP!!!

Of course in our region things can go south in a hurry but at this point in time I am getting pretty excited by what we are seeing. 

 

NOTE: Just wanted to add that this one particular run in being used as more of an example of what we have been seeing on the the GFS and the Euro Op runs in general recently. Due to the chaotic nature of the PAC at this time the timing and evolution of these warm air intrusions varies and will vary from run to run and model to model. So the key take away is that the models argue for these warm air intrusions and not so much the timing.

[BTRWx]

November 2011 was a torch while November 2013 was an ice box.  Showmethesnow is onto something!

[poolz1]

@showmethesnow  Really outstanding writeup!  An enjoyable and educational read... 

[Eduardo]

44 minutes ago, showmethesnow said:

I know I have been pounding on the PAC jet the last week or two but I really think it will be key with our winter. As many already know, and the reasons why, a typical Nina winter is normally bad for our winter chances here in the mid-Atlantic. It features a bad PAC setup and strong jet that quite often overrides other signals that may be a positive for our winter chances. But the last couple of weeks suggest we are dealing with anything but a typical Nina.

Besides what I have discussed previously about the disruptions to the jet (both recently and for the foreseeable future) which weaken it and create a very erratic jet there is one other thing that has fairly recently begun to become a prominent feature. And that is that we are now seeing large intrusions northward of the jet. What this northward progression of the jet is doing is infusing heat into the higher latitudes (polar regions). With this influx of heat we also see an associated rise of heights and as many know this quite often equates to high latitude blocking. This high latitude blocking is what we want to see for our winter chances. Now below I have some examples from the 00Z op run of the GFS.

Here at 78 hr we see a large buckling of the jet that gets fairly far north that is centered on central Canada. One thing not shown is the higher heights and significant ridging associated with it in western Canada. One other feature I want to point out is that we see a southern jet through Mexico and the Gulf.

Now at 144 we once again see the jet moving northward. Notice that wee see a farther progression northward as well as westward compared to the previous one. Not shown is that the higher heights have also shifted northward as well as westward where they are now centered on the Alaskan/Canadian border. Of note again notice we once again see a southern jet popping up through Mexico and the Gulf.

Now look at the 3rd intrusion northward at 186 hour. This is massive intrusion much farther northward then the other two once again centered farther westward over the Bering straits. Not shown but this is sending heat, higher heights and ridging all the way to the pole. Now once again notice to the south. Not only are we seeing a southern jet, we are also seeing a mid latitude jet as well as a polar jet. That's 3 jets running through the CONUS.

Now at hour 288 we are seeing the 4th jet intrusion northward in 12 days. This has shifted back to the east where it is centered close to what we saw at hour 78. But notice that is much farther north then the initial wave seen at hour 78. Not shown is that the higher heights and ridging have shifted back eastward somewhat and continue to extend to the pole. Now once again look to the south. We are seeing a southern jet as well as a mid latitude jet. Not to mention we will have the polar jet dropping into the CONUS shortly. 

Now at hour 384 we are seeing the beginning of another wave forming that should eventually move northward as the other waves have done. This wave looks to be westward of

hour 288 and looks to intrude just as far north. I think the reason we may be seeing these farther north intrusions now are because the initial 3 waves have done the dirty work of scouring out the lower heights around the pole leaving easier access for followup waves. And once again we see 3 jets. A polar, mid latitude and a southern.

Now this constant influx of heat to the pole is having an effect on the PV in the stratosphere as well (50, 30, 10 mb). As below you can see the initial state of the PV where it is located just on the other side of the pole (blue circle). Notice the higher heights (red circle) is located over central Canada and corresponds to where the initial warm air intrusions have occurred.

Now look at day 9. Notice we have seen a shifting of the higher heights (red circle) to the north and west in conjunction with the westward progression of warm air intrusions. In response we see a slight shifting of the PV down and to the right.

Now at day 16 we have a very obvious response from the PV from the constant barrage of warm air intrusions. We see a significant shift, bringing the PV onto our side of the globe into northern Greenland. Now besides the obvious benefit of bringing the pv to our side of the globe is the one thing that the smoothing of the ensembles does not show. These warm air intrusions are wrecking havoc on the pv as well. They are weakening it and contorting it's shape, basically making it dance  a jig. All very good things in regards to not allowing it to strengthen and wreck havoc on our winter chances.

Couple of thoughts on the above. Looking over the 16 days I have to wonder if the model may be suggesting what the possible winter pattern in the Pacific may be (barring any midwinter pattern change of course). Jet induced warm air intrusions (centered western Canada to the Bering straits) initially to the east progressing westward only to return back to the east to begin the process once again. If this is in fact the case this cycle would suggest stable great high latitude blocking. Also of note was the subtropical/southern jet continues to pop up as we have seen for the last couple of weeks. But what is even more significant is that this feature is becoming more pronounced on the models as we progress closer to winter. All I can say about that is, 'Hot Damn'. Final thought. 3 jet streams in the CONUS at once (polar, mid latitude, southern)? SIGN ME UP!!!

Of course in our region things can go south in a hurry but at this point in time I am getting pretty excited by what we are seeing. 

Awesome writeup!!  Question: What, if any of these bucklings are driven by recurving typhoons?

[Bob Chill]

10 minutes ago, Eduardo said:

Awesome writeup!!  Question: What, if any of these bucklings are driven by recurving typhoons?

It's probably a concert of things. Right now the Npac is is progged to be anything but what you normally see in a Nina year. The ridge/trough setup near the Aleutians and GOA is pretty much the exact opposite of Nina climo. I don't think you can pin it on any one thing but I'm pretty confident one of the stronger drivers is the MJO moving through phase 8-1-2

 

 

 

I think we'll see things revert back to more of an aluetian ridge/goa trough as we move through November. However, what is happening now is happening at a really good time. Anything that can help us avoid a consolidated and strong strat PV as we move through Nov can only help us down the line. 

[mitchnick]

42 minutes ago, Bob Chill said:

It's probably a concert of things. Right now the Npac is is progged to be anything but what you normally see in a Nina year. The ridge/trough setup near the Aleutians and GOA is pretty much the exact opposite of Nina climo. I don't think you can pin it on any one thing but I'm pretty confident one of the stronger drivers is the MJO moving through phase 8-1-2

 

 

 

I think we'll see things revert back to more of an aluetian ridge/goa trough as we move through November. However, what is happening now is happening at a really good time. Anything that can help us avoid a consolidated and strong strat PV as we move through Nov can only help us down the line. 

Euro has the MJO dying in Phase 7 Bob fwiw.  This link, which has all the Enso links you need, has it near the bottom. See also the 850 winds forecast that has the trades dying and westerlies taking over. I'm still not convinced we make a technical Nina on the ONI scale.

http://www.stormsurf.com/page2/links/ensocurr.html

[attml]

http://www.cpc.ncep.noaa.gov/products/predictions/long_range/two_class.php

 

[showmethesnow]

2 hours ago, poolz1 said:

@showmethesnow  Really outstanding writeup!  An enjoyable and educational read... 

Thank you. Much appreciated.

2 hours ago, Eduardo said:

Awesome writeup!!  Question: What, if any of these bucklings are driven by recurving typhoons?

Thanks. As far as the buckling of the jet being caused by recurving typhoons I really don't know enough to say. Have read casually on the subject at best and about the only thing I know (at least if I am remembering correctly) is that the storms, especially the stronger storms, later in the season do have an impact in regards to the higher latitudes and the forming pv. I will say that seeing the tropical activity this year in the Atlantic really caught my attention to possible ramifications in regards to the coming winter. The high amount of activity, the number of majors and the tracks (especially the late season storm that passed to the west of The United Kingdom) all signaled to me that we may not be seeing a typical Nina winter setting up.