posted on 27 January 2015
Written by Sig Silber
The Ridiculously Resilient Ridge (RRR) continues to play havoc with the weather. The East Coast is responding as if a powerful El Nino was in place and the West is exhibiting La Nina weather. I am surprised that NOAA has not noticed this pattern. Might the Aleutian Low be involved? I have attempted to shed some light on that in today's Weather and Climate Report. Unfortunately that appears to be a very complicated subject so it is likely that the existing computer models will continue to get it wrong especially in terms of seasonal forecasts.
This is my weekly Weather and Climate Update Report. A more compete report can be found here in what I call Page II of my Weekly Report.
Last week I mentioned that I might decide to discuss the Aleutian Low this week and indeed I have decided to do so. If you wonder why I have decided to discuss this topic, you might pay attention to the amount of discussion of weather in Alaska that is part of the NOAA reports. Both the Tropics and the Aleutian Low have a major bearing on the weather of the Lower 48 States. Here is a good reference on the topic and this is Part II of that article. The Aleutian Low S.N. Rodionov, N.A. Bond, J.E. Overland
Now that you understand the part of the World I am talking about, the following climate-oriented graphic is of interest. The Aleutian Low is a semi-permanent weather feature most prominent in the winter. This graphic represents the mean (average) pattern of the Aleutian Low.
Notice the ridge (the circle in the lower right of the graphic) off the West Coast which IMO is the RRR (Ridiculously Resilient Ridge). Also remember that low pressure areas (such as the Aleutian Low) in the Northern Hemisphere rotate counter-clockwise so the position of the Aleutian Low determines:
My major interest in this weekly report is to examine how the Aleutian Low impacts weather in the Lower 48. I am by no means an expert on this subject but I am doing my best to provide excerpts from the above two articles (which I believe are two of the best articles on this subject) and to provide some explanation that might help the reader understand what is in those two articles. It is a difficult topic and at this point not completely understood.
Compare the above which is the average condition of the Aleutian Low to the Day 3 Forecast.
I apologize for not being able to find a current map: this is the Day 3 forecast but none of the current maps that I could find showed this large an area. Time flies so a Day 3 forecast works just fine. As of today the surface pressure of the Aleutian Low makes it a fairly weak Aleutian Low contrary to the situation in recent weeks. There appears to be a second weaker low off of Siberia and as of yesterday I was not sure that this was one part of a pair of a split Aleutian Low as it appears to be further north than one would expect. Today as I am finalizing my report I am less sure of that than yesterday. But as I want to emphasize, I am certainly not an expert in this area but simply trying to raise some questions. The main low is (was yesterday) forecasted to be further to the east so it has (had) some characteristics of an El Nino situation. Less so today. More on that later.
Here is some more information that I have extracted from the two linked articles (both from the same authors). They are perhaps difficult a bit difficult to read but you can find slightly more readable versions of these graphics at the above links. These are low resolution graphics and unless I had decided to wait and write the author and ask if he would send me some higher resolution versions, we have to work with these and I do think they are adequate for our discussion.
Let us start by considering what is considered the stronger Aleutian Lows which means lower Sea Level Pressure at the center and perhaps some other factors such as the area with low Sea Level Pressure (SLP). Notice the storm track.
And then there are the years with a weak Aleutian Low. Notice the split low with two parts both generally weaker than a single low-pressure system and notice the quite prominent high pressure ridge off the coast of the U.S. Lower 48 States. Also notice the storm track which is interrupted and then reforms.
First the information for the W1 Type
Notice the Aleutian Low is shifted way to the west and the RRR is very pronounced. Also notice the storm track and the absence of significant storm activity one the eastern side of the Pacific in Beringia. Also, with W1 you can see how Bering Strait ice would be melted. I am not going to bore you, but there are special challenges when working with spherical coordinates versus Cartesian coordinates. In theory I am a mathematician and I have to say the discussion of this in the papers is fascinating but not relevant to our discussion.
Then the C1 Type.
Notice the split Aleutian Low and the really pronounced RRR. Also notice the storm track.
At any rate our current situation does not appear to me to be either W1 or C1 (that was my conclusion yesterday but I am not so sure today looking at the updated information) so I am returning to the winter season analysis graphics. The following table relates to Figures 3 and 4 i.e. the winter analysis not the W1/C1 analysis.
In this table I did not use a smoothing algorithm for the AMO and PDO but instead simply recorded their condition as per their associated index for the four- month winter season. I am assuming and fairly certain that the years provided by the author are the year starting in January of the Nov/Dec/Jan/Feb period used to categorize the Aleutian Low as being one of the ten strongest or weakest since 1944 which was a climate shift in the Pacific i.e. the Pacific Decadal Oscillation changed signs.
Curiously this relationship did not apply prior to 1922 so that remains a mystery.
Also of interest, since 1900 the first year in the above graphic, the NP Index appears to be trending lower meaning the Aleutian Lows are getting stronger. Is this Global Warming? The length of the trend suggests that it might be but still one can not explain the lack of the more recent correlation between the NP and PDO during the period 1900 to 1922. Also curiously there appears to be no current measurements of the NP index or ALP index at least that I could find so one wonders if NOAA has access to this data in their computer models.
I may have wished that my investigation would have led me to be able to make some definitive statements about the Aleutian Low but that is not the case. And yet I am left with the feeling that SOMETHING IS UP.
Let us not move from the ultra-theoretical to the much more basic topic of the:
Let us take a look at the 8 - 14 day outlook that was issued today January 26, 2015. It will auto-update every day so it will be changing day by day (and thus be up to date whenever you elect to read this report) but my comments may become out of sync with the map since my comments do not auto-update.
I am only showing the "second week" namely the day 8 -14 outlook. The first week together with much additional information on current weather patterns and near-term forecasts can be found in Part II of my report, but 8 - 14 days covers most of the 6 - 14 day period.
Here is the February Temperature Outlook issued on January 15, 2015. It will be updated on February 2.
And here is the 8 - 14 Day Temperature Outlook.
The cold intrusion from the North projected for the first part of February is not consistent with the full month February Temperature Outlook. It is quite intense.
And here is the updated February 2015 Precipitation Outlook issued on January 15, 2015. So my Report next week will have two sources of predictions: NOAA and The Groundhog. Surprisingly, I think I will be betting on NOAA as I think the Eastern Groundhog will not see his shadow. I am not sure that groundhogs know about the NAO and AO.
And here is the 8 - 14 Day Precipitation Outlook.
The Precipitation Outlook for the beginning of February does not appear to be developing according to the February Outlook especially for the eastern half of the Lower 48.
Today I am also showing the 6 - 10 Day Precipitation Outlook and for variety I am showing the "lines-only" version. It is actually I think easier to read. The letters "A" or "B" show the highest probability of the deviation from climatology prognosticated, and the lines around that show the decreasing probability which ultimately merges with neutral and then usually goes in the other direction. It might print better also.
And now excerpts from the NOAA discussion covering the January 26, 2015 6 - 14 Day Outlook. Some of the highlighted areas reflect the earlier discussion of the Aleutian Low.
Analogs to Current Conditions
Now let us take a more detailed look at the "Analogs" which NOAA provides related to the 5 day period centered on 3 days ago and the 7 day period centered on 4 days ago. "Analog" means that the weather pattern then resembles the recent weather pattern and was used in some way to predict the 6 - 14 day Outlook.
Here are today's analogs in chronological order although this information is also available with the analog dates listed by the level of correlation. I find the chronological order easier for me to work with. There is a second set of analogs associated with the outlook but I have not been analyzing this second set of information. This first set applies to the 5 and 7 day observed pattern prior to today. The second set which I am not using relates to the forecasted outlook 6 - 10 days out to similar patterns that have occurred in the past during the dates covered by the 6 - 10 Day Outlook. That may also be useful information but they put this set of analogs in the discussion with the other set available by a link so I am assuming that this set of analogs is the most meaningful. On a spot check basis, I see less overlap between the prior and projected analogs (adjusted for the differential in timing than I would expect), but so far I have not examined that.
Generally, the analogs are indicating neutral to La Nina conditions. We are told that the PDO is Positive and the AMO is Negative but none of the analogs are associated with PDO+/AMO+. We are also told by various sources that there may be a Climate Shift related to the PDO taking place in the Pacific. I have not commented on this and this article yet but I probably will discuss these two articles in my February 9th Weather and Climate Report.
When you read, listen, or watch weather reports, they rarely discuss what are called low-frequency ocean cycles and the major changes in phase. The medium frequency ENSO Cycle is pretty much the only one discussed in the U.S. In Asia they discuss the IOD. Plus there are other cycles which are generally referred to as atmospheric cycles as opposed to ocean cycles. These include the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) and the Pacific North American Pattern (PNA). The NAO and PNA were discussed in todays 6 - 14 Day Outlook.
There are many scientists, especially at universities, who are knowledgeable in this area. But funding for research is mostly related to Global Warming. This means that many of the scientists (not all) who researched these ocean and atmospheric cycles in the past have developed a bad case of amnesia. That is why I am putting so much effort into explaining the low-frequency (they change phase slowly) ocean and atmospheric cycles. They will dominate the impact of Global Warming for a long time and in some form most likely will continue to exist perhaps modified to some extent as our Planet warms. Those scientists who have developed this Financially-Induced-Amnesia are really doing society a great disservice and I do not respect the choice they have made. Of course in some cases those working on climate are simply ignorant of the low-frequency cycles other than ENSO. Economics mandates that supply and demand will be in balance. Thus the supply of climate scientists will always exactly equall the demand for climate scientists. The issue of quality is a separate branch of economics and depends on the goals and knowledge of the buyer. Again, part of the effort I expend is to increase the knowledge of the buyer of climate information.
Back to the Current Situation:
Sometimes it is useful to take a look at the location of the Jet Stream or Jet Streams. You can see how the ridge of high pressure off the West Coast is currently still forcing the Jet Stream inland and then creating a large trough in the center of the Lower 48.
And sometimes the forecast is revealing. Below is the forecast out five days. It kind of reveals the opportunity for what are called Baja Lows to develop which will be very welcome where I live.
To see it in animation, click here. At the time this article was published, the animation shows a tendency for there again to be a Southern Branch of the Polar Jet Stream in addition to the usual Northern Branch. A southern stream can bring storms further south than usual. But you can see how the situation is becoming more zonal which should reduce the cold air intrusions from Canada.
This longer animation shows how the jet stream is crossing the Pacific and when it reaches the U.S. West Coast is going every which way. One can imagine that attempting to forecast this 6 - 14 days out is quite challenging.
And below is a another view which highlights the highs and the lows re air pressure on Day 6. Here it definitely looks like a split low situation..Type C1. Boy am I glad I do not do Meteorology for a living. This would drive me crazy.
The Aleutian Low forecast out six days is again quite strong as compared to the Day 3 forecast. In December it was El Ninoish. Now it seems more ENSO Neutral or at least that is my interpretation. Notice the split Aleutian Low. I may not have done enough research to fully understand this but you can see visually that the present configuration is more consistent with the weather we are having than with the NOAA Seasonal Outlooks. That is why I have raised the question of whether or not the Aleutian Low is behaving in a way that is a bit odd.
El Niño Discussion
Now let us look at the latest NOAA Hovmoellers. I had hoped that this might be the last week that we will need to look at the Hovmoellers this winter if I concluded that it really is a done deal....ImagiNiño: end of story. But I tend to think that this is just the beginning of the story with many more chapters to follow.
There are many graphics that NOAA provides every Monday but I focus on a subset of the information provided and today I thought I would again start with what probably is the most important one that I call the Kelvin Wave graphic but it is really the Upper Ocean Heat Anomaly along the Equator which is caused in many cases primarily by Kelvin Waves.
There is again quite a bit of change since last week. The most recent Kevin Wave is of course no longer a direct factor although the warm water brought to the surface has to be dealt with through evaporation (which cools the water surface while producing convective clouds). The upwelling phase now even more clearly shows a cooling anomaly as it moves east. The next Kelvin Wave looks like it may be close to being declared and may be showing up in the forecast models as predicting a summer El Nino i.e. a 2015/2016 El Nino rather than a 2014/2015 El Nino which has been the primary focus of NOAA. With a couple of triangles you can make your own forecasts of when this possible new Kelvin wave will IMPACT THE COMPUTER MODELS. This in turn will impact the Seasonal Outlooks issued by NOAA. But it may not impact the weather. History tells us that El Nino events develop prior to Christmas which is how they got their name. An ONI greater than 0.5 in March and April is interesting but not necessarily as significant as an ONI greater than 0.5 in December. I will be interested in what NOAA has to say on Saturday when they update their February Outlook.
Now let us look at the Sea Surface Temperatures
Again there is some change since last week as you can see even less warm water along the Equator. Overall there is not much new information in this graphic.
Of most interest to NOAA is 120 W to 170 W as that is where the ONI Index is measured. More information can be found here. If you look at the color coding in the above Hovmoeller they are looking for shades where the redder the better re conditions being El Nino but so far it is just showing shades of tan and brown i.e. marginal especially when averaged over the entire area of interest. But that explains why we have a situation where some of the factors are in place for an El Nino but so far it is marginal at best and fading fast.
And now the low-level wind anomalies.
This shows some change from last week. The Southern Oscillation Index (SOI) has been very strong especially early this week to revitalize the "ImagiNiño". You can find the daily and 30 and 90 day averages here. The 30 day average of -9.09 (through the January 26 reading) is consistent with El Nino conditions (a 30 day average of -8.0 or more negative is considered to be consistent with El Nino conditions). The first four readings of the week are amazingly strong readings. The next three readings which were not available at the time of publication, which I have since added, are also strong but not nearly as strong. You can see the impact of this in one of the above Hovmoellers and in the TAO/Triton graphic further down in this Report. The SOI fluctuates based on local weather conditions in Tahiti and Darwin Australia so one week of data is not sufficient to draw conclusions but it may be what has gotten some of the computer models a bit excited.
I noticed this morning that this website had started to post updates so I have added them to the article which was published last evening.
I realize this looks like a rather impressive string of negative SOI values so I thought I would show what things look like this year compared with the most recent very powerful El Nino namely the 1996-1997-1998 period. Notice the SOI went very negative early in 1997. That is why I have concluded that if there is to be an El Nino it is likely to be a 2015/2016 El Nino not the 2014/1015 El Nino that NOAA has been advertising.
And here is the current reporting of the SOI.
And finally the latest model results released by NOAA on January 26, 2015.
This graphic is a modified version of the graphic that appears on Page II of this Report. It is modified by NOAA to be consistent with the maps on the right which can be found here. Those maps have been processed to adjust for the observed skill of the models. As you can see, December was the peak of this El Nino and January is clearly sub-El Nino on the ONI scale. But now all of a sudden the mean estimate for February is actually in El Nino territory. The most curious aspect which has has been the case for months is the way the model estimates rise into summer but that has tapered off. I have not mentioned this before but when you look at this chart, it is useful to look at the red or older forecast members and the blue or more recent forecast members used to create the mean estimate. This provides some insight into where this forecast is headed as older model runs drop out. It most likely will be sub-El Nino next week and probably perversely higher the following week.
Here is another graphic that confirms that we are not in an El Nino but which is very interesting. The top graphic shows conditions along the Equator, 10 degrees north to 10 degrees south of the Equator and this is one of the most up to date sources of information available. The top graphic shows surface temperatures and wind direction and speed. The bottom graphic shows anomalies.The bottom graphic shows the deviation from average conditions. You can see two things in that graphic. First of all you can see the pockets of warm water which are in some cases greater than 1C above average and in other cases below 0.5C above average conditions. Looking between 170W and 120W on the Equator, you see a larger area where the anomaly is under 0.5C than you see an area above 0.5C. That is how I make my own estimate of the ONI. Also the anomaly analysis of the winds generally point to the West except for the last few weeks around the Date Line (180 degrees Longitude) which to me is another indication that this might be more like a Modoki than a canonical/traditional El Nino. But this week, those westerly anomalies extended quite a bit further west which suggests that the ONI readings will increase in the near term. It must be very frustrating for the forecasters when some of the factors necessary for an El Nino are in place but not all of them and there are many different varieties of El Nino and La Nina and these varieties impact World Weather differently.
Pulling it All Together. .
So this continues to look to me like a warm event that is not a full fledged El Nino this year but which may last longer than NOAA thinks and have different impacts than they think also. So far that has certainly been the case. We shall see if that continues. I am still thinking the Japanese sized this up from the start and that this is really more like a Modoki than a traditional El Nino and that weather patterns are shifted some number of degrees further west (or possibly rotated) than would be the case for a traditional El Nino which is why the weather where I live is more typical of a La Nina than an El Nino. This has been the case since the PDO went into its Negative Phase which is why a possible change to PDO Positive is so very important.
I do not see a traditional El Nino of any significant strength likely to happen this winter although a "near" El Nino appears to be making its presence known to a limited extent but mainly outside of the U.S.. It appears to be a very complicated situation mostly because of the at least temporary shift of the configuration of the Pacific with respect to the location of warm and cold water to a configuration which is called PDO Positive (+) combined with the Blocking Ridge off the West Coast.
An El Nino Watch for next year might be in order as there remains a lot of warm water but usually it takes a few years for that to built up sufficient for another warm event to get under way. ENSO neutral is where the models are headed and I suspect that they have it correct.
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