Winter 2013-14 medium range discussion

[mempho]

the warming occurred during a synoptic pattern that should produce widespread cold is a sort of "red flag." But one still needs to wait. I believe we'll have our answer by near or at the end of this month.

Don,

Do you have any ideas on what the reason for this is?

Sent from my SCH-L710 using Tapatalk

[Harry]

Question is what is causing this warmth up there? 2011-12 can also be explained in that we had a spike in solar activity ( if i recall correctly in Nov? ) along with a -QBO East which typically goes hand in hand with the pattern we had down here in the lower 48 and up there across the Arctic?

[mempho]

Question is what is causing this warmth up there? 2011-12 can also be explained in that we had a spike in solar activity ( if i recall correctly in Nov? ) along with a -QBO East which typically goes hand in hand with the pattern we had down here in the lower 48 and up there across the Arctic?

Correct, but has this not been really weak as far as solar maximums go?

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[donsutherland1]

Don, Do you have any ideas on what the reason for this is? Sent from my SCH-L710

 

The exact synoptic details can make a difference, but in this case, the warm anomalies were widespread across the Arctic. In recent years, one has seen greater tendency for AO+ patterns to wind up warmer to much warmer than had been the case even into the 1990s.

[Harry]

Correct, but has this not been really weak as far as solar maximums go?

Sent from my SCH-L710

 

Oh yeah it has.. Still activity has picked up a bit from where it was say in 2009..

[donsutherland1]

This morning, the Arctic Oscillation (AO) Index stood at +3.716. That's the highest reading since December 25, 2011 when the AO was +3.824. A number of ensemble members forecast the AO to peak at or above +4.000. The November montly record is +4.544, which was set on November 2, 1978. In the extended range, the MJO is forecast to be meandering through Phase 1, which may suggest a continuation of mild periods alternating with some cool shots. If so, the ridge in the West/trough in the East showing up on the ensembles for the extended range could be transient.

 

In the meantime, on a more wintry note, it does appear increasingly likely that Baltimore, Philadelphia and New York City and adjacent suburbs could see some snowflakes overnight into tomorrow morning with some coatings on grassy surfaces. Cities such as Cleveland and Pittsburgh might pick up a light accumulation of snow tonight.

[WXheights]

Maybe, Don's one of the best we got, but the science is really tough to perfect.

 

Keep in mind, those anomalies today are only 1-3C above normal (based on eyeballing the map)... When a -40F airmass is running -37F, the deciding factor will still be jet dynamics. If the arctic is slightly warmer, the jet should relax south a bit more according the arctic amplification sciences, so I have to wonder if it will help or hurt us.

 

I'm only a hobbyist, but I'm really a big pacific index follower, the PNA is going to make or break our winter.

A lot to figure here.  +AO general = warmth mid latitudes. If you read latest from Ricardo OPI signal they come up with "compact PV" set up was a sort of bookend winter (North America) with below normal temps blasting in from time to time (+PNA) November, first part of December then somewhat a torch until later February bookend backloaded winter to more variability - March?. Don's conclusions which I think he used Nov. which may statisitcally back up this idea. But I think the PNA flipping will be the back door letting in the cold air as main key over topping Alskan ridge, while AO/NOA neutral to way positive. I have seen many other clonficting ideas inlvolving solar minimum (talk of Maunder minis) and then enter  whacky jet  slowing config with AA Francis Vavrus. Darts anyone?

[donsutherland1]

Today, the Arctic Oscillation was +3.302. That marks the 5th consecutive day on which the AO has been at or above +3.000. For the month, the AO is averaging +2.679. The November record is +2.470, which was set in 1978.

 

It appears very likely that the AO will average at least +1.500 to +2.000 for the month. For the AO to finish the month with a +1.500 average, it would need to average +0.714 per day for the remainder of November. For it to average +2.000 for the month, it would need to average +1.547 for the rest of November. To beat the 1978 record, it would need to average +2.332 for the rest of the month.

 

Since 1950, November has had 14 cases during which the AO averaged +0.500 or above for the month. 10/14 (71%) saw warmth focused in the East in December. There were four exceptions: 1975, 1977, 1993, and 2003. Frequently, one saw the December pattern beginning to evolve during the closing 10 days of November. There were exceptions. With a period of blocking becoming increasingly likely during the closing days of November, one will need to watch for an atypical December outcome following the AO+ November. I'll post my December thoughts in this thread in the next 10-14 days.

 

For now, I've listed some charts showing the typical and atypical December cases. I've also included partial teleconnection and partial ENSO-teleconnection cases for the 11/20-30 period (1981-present, not the full 1950-present data). Those cases show an area of warmth displaced for what one sees with respect to the typical December cases, but not the kind of widespread cold one often sees during the atypical ones. For now, the early odds still seem to favor the more typical cases, but things have at least grown a little more interesting.

 

 

[uncle W]

I looked at a few plus ao winters and the findings aren't great...some of these had a negative February but overall the winters had a plus ao...

 

[donsutherland1]

Brief evening update...

 

11/13/2013 0z run of the GFS was cold for the eastern U.S. in the extended range. That fits with the extended range of the earlier run of the GFS ensembles. It also matches up well with the objective analogs (based off the GFS ensembles) rolled forward to be centered on 11/26 and the temperature anomalies for the 11/22-30 period resulting from the combination of ENSO and the forecast teleconnection indices.

 

Unlike the patterns that preceded the atypical outcomes following a November AO of +0.50 or higher (Message #38), there is a large area of warmth present. The atypical cases saw the 11/20-30 period with widespread cold in the CONUS. Instead, the maps suggest that most of the cold would remain in Canada. That might imply that the cold shots are part of a transitional period, which would culminate in the more typical December cases. Indeed, if one rolls forward the ENSO-Teleconnection cases, the warmth does spread into the East afterward.

 

The following are the maps from the ENSO-teleconnections and objective analogs:

 

[donsutherland1]

In last evening's message (#40), I noted that if one rolls forward the ENSO-Teleconnections cases, the colder pattern shown for the 11/22-30 timeframe eventually yields to a warmer one. That outcome would be consistent with the tendency for December to see warmer than normal readings in the East following a November with an AO of +0.5 or above. November 2013 is very likely to have a figure of +1.5 to +2.0 or above.

 

Another argument for the transitional period marked by swings between cold and warmth is the MJO. The MJO has recently moved from Phase 8 to Phase 1. It is forecast by a lot (but not all) of the guidance to be moving into Phase 2 or Phase 3 toward the end of November or early in December. Should the MJO progress through Phases 2 and 3, such a progression would be consistent with the development of warmth consistent with the typical outcome following a positive or strongly positive November AO.

 

The November-December-January composite temperature anomalies for the MJO are below:

 

 

It should be noted that there can be some exceptions, but the map gives an idea concerning the temperature anomalies related to the MJO's phases.

 

All said, odds continue to suggest that December 2013 will probably wind up warmer than normal in the East and possibly a fairly extensive portion of the CONUS.
 

[Jonger]

Euro weeklies all flipping to cold through the first week of December.

[Kevin Druff]

Don, in one of his recent blogs Joe Bastardi discussed the similarities in the Pacific to 1993-94 and I wondered your thoughts. I discussed this winter with Anthony Sayles (RIC Airport) and how it was very much Pacific driven. I wondered what your thoughts were on that winter and what you think are similarities/dissimilarities between the years. 

[donsutherland1]

Don, in one of his recent blogs Joe Bastardi discussed the similarities in the Pacific to 1993-94 and I wondered your thoughts. I discussed this winter with Anthony Sayles (RIC Airport) and how it was very much Pacific driven. I wondered what your thoughts were on that winter and what you think are similarities/dissimilarities between the years. 

 

IMO, the Pacific will most definitely have an important impact this winter. The prevalent EPO- has helped lead to some fairly impressive cold shots (today's produced some of the earlierst < 30° readings in the Mid-Atlantic since the early 2000s.

 

However, while both November 1993 and November 2013 saw a large polar vortex, the current AO+ regime is stronger. Both also witnessed persistent above normal anomalies near Alaska. However, 2013's height anomalies have been displaced to the west of those in November 1993. Unlike 2013, the PDO was positive during a long-term warm cycle in 1993. All ENSO regions had generally been running modest warm anomalies prior to winter 1993-94.

 

During December 1993, the polar vortex began to split and by mid-month it had split. At the same time, exceptionally cold air covered much of the Arctic region with widespread anomalies of 6°C/10.8°F below normal and colder. The Arctic has recently been running warmer than normal in general, though there is still an area of colde anomalies, but the expanse and magnitude of the cold is less than it was in 1993. The polar vortex would remain split for an extended period of time including throughout much of January 1994 allowing this exceptionally cold air to eventually pour into the CONUS.

 

In sum, I suspect that both the subtle differences (PDO, placement of predominant synoptic features, and stronger/more polar vortex this time around) will lead to a different outcome from winter 1993-94. I'm still not fully certain on how all the Pacific features will play out, though it seems an EPO closer to neutral than negative is probably more likely than the impressive EPO- that developed during January 1994. Many of the most prominent EPO- periods occurred when the PDO was positive (particularly during its warm long-term cycle).

 

Of course, I could be wrong.

[donsutherland1]

Euro weeklies all flipping to cold through the first week of December.

If December is to turn warm on average (Great Lakes and East), I suspect that the timing of the turn will probably be somewhere in the 12/5-10 timeframe, as the guidance often rushes changes. That tendency to rush changes might well be the reason the weeklies have turned to cold through the first week of December. Also, the idea that a cold period might last, in the means, through the first week in December is not unreasonable, especially if one assumes that the MJO might not reach Phase 3 until sometime during the 1st week in December or somewhat afterward. That assumes it will progress as modeled, and some differences on the guidance exist. Fortunately, all of this is still far in the extended range, so there may yet be more changes.

[Wow]

You wouldn't know it's been a +AO November based on where I'm sitting!

 

[donsutherland1]

You wouldn't know it's been a +AO November based on where I'm sitting!

 

 

Still shorter wave lengths may have something to do with it. Interestingly enough, I ran the dates for the following parameters for the the November 1-15, 1950 through 2012 timeframe when ENSO Region 3.4 anomalies were above -0.5°C and below +0.5°C:

 

AO: +1.5 to +3

PNA: -1 to 0

EPO: -2 to 0

 

That's similar to where we've been for the first 13 days of November.

 

The composite temperature anomalies for North America were:

 

 

The most similar period was 11/6-8, 12, 14-15/2012:

 

 

[Srain]

You wouldn't know it's been a +AO November based on where I'm sitting!

 

Agreed. We are running well below normal down here along Coastal Texas. In fact we are ahead of schedule with our first freeze just N of Houston and as we saw with the Tropical Season forecasts back in March, April and May there tends to be little skill in longer range forecast ~vs~ reality. One has to wonder what that warm pool of SST's in the N Pacific will do regarding these longer range forecast speculations.

[SnowGoose69]

You wouldn't know it's been a +AO November based on where I'm sitting!

 

 

As Don said the wavelengths are probably a huge reason why, its not unusual for the AO whether it be decently negative or positive to sometimes see the pattern be the opposite of what you'd expect given the phase in November and sometimes even December, it seems Jan/Feb is where the AO state has the biggest influence.  Remember last December despite the very negative AO it was very mild for many areas.  The one major positive I see so far is the models attempting to occasionally drop in a GOA low in the medium or longer range only to see it more back to the Aleutians or be non-existent completely.

[Damage In Tolland]

The Pacific certainly trumps any of the Atlantic indices. This seems to be heading into one of those winters where the Atlantic side really doesn't matter that much nor the AO. There's been some great posts in SNE forum from mets on why that might be the case this year..and why we may be looking at a cold winter. Perhaps that's what the Euro seasonal and CFS are keying on .

[Wow]

As Don said the wavelengths are probably a huge reason why, its not unusual for the AO whether it be decently negative or positive to sometimes see the pattern be the opposite of what you'd expect given the phase in November and sometimes even December, it seems Jan/Feb is where the AO state has the biggest influence.  Remember last December despite the very negative AO it was very mild for many areas.  The one major positive I see so far is the models attempting to occasionally drop in a GOA low in the medium or longer range only to see it more back to the Aleutians or be non-existent completely.

 

As long as that warm pool in the N Pac holds closer to the GOA, we should expect more ridging here, and the Aleutian Low to maintain where the cooler waters reside.  I think this helps explain why models forecasting otherwise have failed as we move closer into the time frame.

[Jonger]

The Pacific certainly trumps any of the Atlantic indices. This seems to be heading into one of those winters where the Atlantic side really doesn't matter that much nor the AO. There's been some great posts in SNE forum from mets on why that might be the case this year..and why we may be looking at a cold winter. Perhaps that's what the Euro seasonal and CFS are keying on .

What are the chances the AO keeps dropping like the CPC indicates and we aren't in a positive AO winter to begin with.

[Harry]

One of the things gnawing at me is Nov 78 and 93 vs Nov 94 and 11?? Anyone wanna guess why? The outcomes were totally different BUT WHY? Thus why was 78-79/93-94 so cold were as 94-95/11-12 the total opposite? BOTH sets had the Nov +AO? So what made the difference? Enso? QBO? Solar? Something else or perhaps a combo of all?

[ORH_wxman]

One of the things gnawing at me is Nov 78 and 93 vs Nov 94 and 11?? Anyone wanna guess why? The outcomes were totally different BUT WHY? Thus why was 78-79/93-94 so cold were as 94-95/11-12 the total opposite? BOTH sets had the Nov +AO? So what made the difference? Enso? QBO? Solar? Something else or perhaps a combo of all?

 

 

The stratospheric temps were frigid over central/east Siberia in the bad years...this is a strong pretense to the winter AO state:

 

 

 

 

 

 

 

 

 

 

 

 

Admittedly, the good composite isn't quite so obviously pointing to great winters (more of a neutralish signal)...but it was at least wasn't showing the worst possible scenario like 1994/2011 were.

[Harry]

The stratospheric temps were frigid over central/east Siberia in the bad years...this is a strong pretense to the winter AO state:

 

 

 

 

 

 

 

 

 

 

 

 

Admittedly, the good composite isn't quite so obviously pointing to great winters (more of a neutralish signal)...but it was at least wasn't showing the worst possible scenario like 1994/2011 were.

 

 

Thanks Will.. Thus why i cannot hop on board with the warmer calls and or give those years ( namely 11-12 ) much weight. Well not as much as a few others seem to be giving them.. Ofcourse 78 seems to be the one that matches SOLAR/ENSO/QBO the closest and perhaps AO itself if it stays like it has. I however cannot see going as cold as that was either.. sigh..

[toronto blizzard]

Is the stratosphere frigid in Siberia like what some people are claiming?

[donsutherland1]

Development of Blocking Increases on the Guidance...

 

If one takes a look at the images in the first message in this thread, one finds a much more pronounced blocking signal toward the end of the month. If one also examines the EPO forecast, the EPO is projected to be negative to strongly negative in the extended range. Does this mean a cold December might be in store for the eastern half of the U.S./eastern part of southern Canada and a warm one in parts of the western U.S.?

 

For me, it's still too soon to tell. Several factors continue to argue against it:

 

1. The typical December temperature anomalies following a November with an AO of +0.5 or above (there are some atypical cases)

2. The forecast progression of the MJO

 

It should also be noted that the CFSv2 monthly forecast for December has just changed to a cold in the East/warm in the West idea. That idea is remarkably similar to the composite anomalies for the atypical November AO+ cases (maps posted in Message #38).

 

One other thing I do daily is to run partial cases based on the forecast teleconnection indices. These partial cases exclude ENSO, as I use them mainly for watching trends. The December idea that will be posted in the next 7-10 days will include ENSO, among other additional variables.

 

The partial cases from this morning's guidance were: 1982, 1991, 1995, 1996, 2000, 2001, 2007, 2008, 2010, 2012

 

I took those cases and ran the maps for November, December, and also created maps for the November 1-12, 2013 period. I did this for North America and Europe. Those maps are below:

 

North America:

 

Europe:

[Isotherm]

Is the stratosphere frigid in Siberia like what some people are claiming?

 

 

No. It's currently closer to the years that featured a more favorable AO than the worst case scenario of 2011.

 

 

 

 

[icebreaker5221]

No. It's currently closer to the years that featured a more favorable AO than the worst case scenario of 2011.

 

Mixed signals (what else is new).  Although 50 mb temps within the arctic circle are not as bad as the worst +AO seasons, the locations of the + and - anomalies are much more consistent with 2011, 1994 than 1993, 1978.  Note the peak negative anomaly closer to Siberia, with distinct cold anomalies over the SE U.S. and positive anomalies over the N Atlantic.  We'll have to see how the stratosphere plays out the rest of the month to get a clearer picture.

[HeatMiser]

Development of Blocking Increases on the Guidance...

 

If one takes a look at the images in the first message in this thread, one finds a much more pronounced blocking signal toward the end of the month. If one also examines the EPO forecast, the EPO is projected to be negative to strongly negative in the extended range. Does this mean a cold December might be in store for the eastern half of the U.S./eastern part of southern Canada and a warm one in parts of the western U.S.?

 

For me, it's still too soon to tell. Several factors continue to argue against it:

 

1. The typical December temperature anomalies following a November with an AO of +0.5 or above (there are some atypical cases)

2. The forecast progression of the MJO

 

It should also be noted that the CFSv2 monthly forecast for December has just changed to a cold in the East/warm in the West idea. That idea is remarkably similar to the composite anomalies for the atypical November AO+ cases (maps posted in Message #38).

 

One other thing I do daily is to run partial cases based on the forecast teleconnection indices. These partial cases exclude ENSO, as I use them mainly for watching trends. The December idea that will be posted in the next 7-10 days will include ENSO, among other additional variables.

 

The partial cases from this morning's guidance were: 1982, 1991, 1995, 1996, 2000, 2001, 2007, 2008, 2010, 2012

 

I took those cases and ran the maps for November, December, and also created maps for the November 1-12, 2013 period. I did this for North America and Europe. Those maps are below:

 

North America:

 

Europe:

 

 

Hi Don,

 

I'm not sure I follow your +AO and MJO thoughts on risks for a warm december.  Despite a record positive AO, we are seeing especially cold bursts continue to hit the east coast once a week.  To me, the record positive AO is only going to increase the chances of a severe cold spell, if we do in fact see a -NAO develop given how cold it is in the Arctic.

 

With regards to the MJO, it's mostly been in the circle of death and not really flexing its influence.  I'm not sure why barely breaching into phase 1-3 would do anything significant for a warm december anyways.