posted on 06 July 2015
Written by Sig Silber
The end of month update only covers the following month but sometimes that data also provides clues with respect to subsequent months - and I think that is the case this time. Also July does not appear to be evolving exactly as projected in the June 30 Update and involves a fairly complicated pattern change. Thus confidence in the second week of the 6 - 14 Day Outlook is less than usual. Meteorological Agencies continue to project that this El Nino will strengthen and hang around for a while but I will discuss why I think it is a short-timer. The North American Monsoon appears to be developing a bit further west than earlier predicted. So there is nothing major to discuss but there are a number of different issues which will impact weather where you live.
This is the Regular Edition of my weekly Weather and Climate Update Report. Additional information can be found here on Page II of the Global Economic Intersection Weather and Climate Report.
New maps were issued by NOAA for July on June 30. 2015 as part of their regular update schedule. The Seasonal Outlook will be updated on July 16, 2016.
Not much change other than a tendency for the colder than climatology area to tilt a bit to the east..
Here we see the drier Northwest showing up and the wetter than climatology area extending further to the east and west. But the 6 - 14 Day Outlook is calling this monthly outlook into question to some extent.
It is useful to put the current month updated maps in context with the prior three-month Outlook. Unfortunately at the time I needed to submit this article NOAA had not yet posted the graphic on their website so I created my own version of what it will look like when it does get posted. THE GRAPHIC BELOW IS A MOCKUP OF WHAT I BELIEVE THE OFFICIAL NOAA GRAPHIC WILL LOOK LIKE. IT HAS NOT YET BEEN ISSUED BY NOAA. THE INDIVIDUAL MAPS ARE NOAA MAPS. I SIMPLY CREATED THE COMBINATION OF FOUR OF THEIR MAPS WHICH THEY WILL DO SHORTLY. And I do this simply to make it easy to compare them rather rather than having to jump back and forth from four larger versions of these NOAA maps.
As you can see there are differences between the updated July Outlook and the prior three-month Outlook. Such differences could be the fact that one month is only a third of a three-month outlook but earlier we observed that the updated July maps were a bit different than the maps issued on June 18. So I do believe the above is suggestive of some updated thinking about August and September which we can attempt to deduce from the above graphic. One might be concluding that August and September may have a slightly different warm-cool-warm west to east pattern much like the July map and one might be concluding that the Midwest to the Northeast might we wetter. I am not drawing any conclusions about the Northwest as that was clearly explained as being an early-July impact.
Here are excerpts from the NOAA Discussion issued on June 30, 2015
Current (Now to 5 Days forward) Weather Situation:
For daily forecasts it is better to consult your local weather service or the weather service where you are traveling as these will be more specific. But I do have daily forecasts on Page II of the Report so you can always look at those as they auto-update. What I present here is information that normally is not made available via local weather forecasts and which can help you understand what some of the major drivers are for the local forecast.
First here is a national 12 hour to 60 hour forecast of weather fronts shown as an animation. Beyond 60 hours, the maps are available in Part II of the Global Economic Intersection Weather and Climate Report.
The explanation for the coding used in these maps, i.e. the full legend, can be found here.
The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients. You can see the Four Corners High where Utah, Colorado, Arizona, and New Mexico meet. At this time of the year, small changes in the location of that feature make a big difference in the weather of probably about ten or more states. Note the projected location of the Four Corners High. It possibly explains the projected western shift in the impacts of the North American Monsoon (which probably is more properly called the Sonoran Monsoon). .
It certainly explains the warmer than climatology conditions in Texas. But this High moves around a lot so by the time you view it most likely it will be located somewhere else. But you can always imaging the clockwise circulation and how that might impact the movement of moisture in from the Gulf of Mexico and up from Mexico and in from the Gulf of California. So this graphic can very very useful. And it auto-updates, I think every six hours.
In the Tropical Weather Outlook graphic below, notice the stream of moisture moving north from Mexico into the Southwest. To some extent this is enhanced by the position of the extreme western edge of the influence of the Bermuda High. It is not a full fledge Southwest Monsoon but it is part of the pattern that is currently making CONUS unusually wet.
Below is another view which highlights the surface highs and the lows re air pressure on Day 6 (Day 3 can be seen in Part II of this Report). The Aleutian Low refuses to take its usual summer vacation and that may be related to the El Nino. The RRR has moved further off shore and the Northwest can now more easily receive warm wet air from the Pacific. You may be able to see an "L" on the map in that area but remember these maps update every six hours.
Outlook Days 6 - 14 (but only showing the 8 - 14 Day Maps)
Here is a graphic of the July Outlook issued June 30, 2015:
And here is the 8 - 14 Day Temperature Outlook issued today July 6, 2015.
It covers the week following the current week. Today's 6 - 14 Day Outlook is just nine days of the month and the map shown of the 8 to 14 day Outlook only shows seven days. Other than the Southeast, these is little resemblance to the updated monthly forecast issued just six days ago. NOAA describes the change as a southward shift in the pattern on the eastern half of CONUS.
And here is the Outlook for July Precipitation issued on June 30, 2015:
Here is the 8 - 14 Day Precipitation Outlook issued today July 6, 2015:
And again remember that this map shows only seven days and the full 6 - 14 Day Outlook only covers nine days. There are 31 days in July.
It looks like the situation in the Northwest has changed from earlier in the month and it now appears that the Northwest will participate in the precipitation party. This is consistent with the June 30 NOAA forecast. But the Southwest is likely to be less wet than foreseen on June 30. It is as if the drier than climatology area in Texas has been shifted to the north. So the temperature pattern further east has shifted to the south and the precipitation pattern a bit further west has been shifted to the north. That also has shifted the entry point of the North American Monsoon a bit to the west. It looks to me like the Bermuda High is having an impact on the pattern and we can expect that to often be the case in Spring and Summer for the next thirty years due to the progression of the AMO.from AMO+ to AMO- and the influence of the AMO on the positioning of the Bermuda High. NOAA does not discuss the Bermuda High very much in terms of overall weather patterns in CONUS and does not seem to consider the interaction of the Bermuda High location and the AMO progression. I have discussed this a few weeks ago and may repeat that discussion again in the near future but the articles are available on Page II of this Report.
Here are excerpts from the NOAA discussion released today July 6, 2015.
Analogs to Current Conditions
Now let us take a 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 forecast 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.
It is interesting that of the ten possible analogs, there were four duplicates which suggest that the prior week has had a fairly consistent pattern. There are ten analogs provided by NOAA and the most duplicates there can be would be five and this week there were four which is the most I have seen since I started to look at them. Also of interest is the three 1951 and 1952 analogs. That was a period of extreme Southwest drought but there was a moderate El Nino in 1951 and again in 1952 but later in the year than the analog provided. The ocean conditions during that period were McCabe D. So even during a period when the oceans signify Southwest drought, there are El Ninos. The ocean phases associated with the analogs this week point towards McCabe Condition C or D. They are pretty much mirror images of each other and the location of wet and dry is controlled by the PDO. That is another reason for the quandary about the latter part of the 6 - 14 Day Outlook.
You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with each of the four pairs of two phases of the AMO and PDO.
Historical Anomaly Analysis
When I see the same dates showing up often I find it interesting to consult this list.
Progress of the Warm Event
Let us start with the SOI.
Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day running average and the third is the 90 day average.
This past week, for the second week in a row the SOI exploded to the downside which in theory assists the development of the current El Nino but in practice may be too late. The 30-day average, which is the most widely used measure, on July 6 was reported as being -15.14 which is clearly an El Nino reading. The 90-day average also is now again in El Nino territory at -10.77.
The presumed reason for this quite likely is the Madden Julian Oscillation (MJO) which is a 40 to 60 day cycle around the Equator and is in its active phase right now where the SOI is calculated. It is controversial as to whether or not the MJO has an impact on Kelvin Waves. But we need to pay attention to whether or not this active phase of the MJO leads to a new wind burst and new Kelvin Wave. This will occur again probably around Mid-August so that will be last time that the MJO may impact this El Nino.
Here are the low-level wind anomalies. This graphic is not as compact as the graphic provided by the weekly NOAA ENSO Report (more white space) but this version auto-updates so you will always have the latest version of this Hovmoeller. As you can see, the wind gust of a several weeks ago at 160E is over and a subsequent less intense wind gust at 160W to 140W has also played out. There may be some activity starting in the Western Pacific that is just starting to show up on this graphic. Take a look over at 130E to 140E which by chance happens to be Darwin Australia one pole of the SOI Index. I think this is too far west to impact the current El Nino. But we can now see some very intense activity at 160E which is much more significant and needs to be monitored. 160E is where the prior Kelvin Waves formed and if you look earlier in this Hovmoeller you can see that in Feb, Mar, and May. Will it happen again now? That is very very important. Is there enough warm water there to create a substantial Kelvin Wave? I do not think so.
Here is another graphic that is less compact than the prettied up version published by NOAA on Mondays but which has the advantage of auto-updating. You can see how the convection pattern (really cloud tops has in May shifted to the East from a Date Line (180) Modoki pattern to a 170W to 120W Traditional/Canonical El Nino Pattern. The signs of an El Nino are getting quite faint and shifting to the west. The probably impacts on CONUS are thus lessened.
Let us now take a look at the progress of the Kevin wave which is the key to the situation. I like this Hovmoeller a lot and I have now been able to find a version that autoupdates but is not prettied up. I will take the auto-update feature. You can see the Kelvin Wave that got started in February which started this Warm Event. There have been earlier such events that proved to be not very strong. But if you look at the bottom of the Hovmoeller which represents the current situation, you can see that this latest Kelvin Wave is moving to the East fairly rapidly and we will see the impact of that on declining ONI estimates fairly soon. The strongest impact is no longer shown on this graphic as it occurred a week or two ago. The main impact of this Kelvin Wave is already East of 170 West the western-most extension of the Nino 3.4 region. In less than two months it has moved to the east 30 degrees of longitude so I think that within 2.5 months (i.e. Early October 2015), the ONI values will be way under 1.0 and very close to ENSO Neutral. OH MY GOSH. On the NOAA version of this graphic in their weekly ENSO EVOLUTION REPORT they actually highlighted with the following comment: "Since early June, an upwelling phase of a Kelvin wave has shifted eastward". the upwelling wave to the left or west side of this graphic which signifies the end of this El Nino event. I have discussed that area of cooler water for a couple of months and today NOAA has recognized it. So far there is no indication of a follow-up Kelvin wave being created but that will be noticeable or not within a week or so. I suspect that it will not happen. If it does not happen, I believe the various computer forecast models will turn out to have been very over-optimistic about the duration of this El Nino. Impacts however can linger for a couple of months after a Warm Event no longer registers as an El Nino as weather teleconnections do not travel at the speed of light but more like at the speed of wind.and weather patterns.
You can see below in the graphic which shows temperature along the Equator as a function of depth, both the magnitude of the anomalies and their size. You can now see where 2C (anomaly) water is impacting the area where the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to about 135W and the blips visible further to the west are no longer evident. The subsurface warm water appears to be making its way to the surface to some extent. This will be apparent when we discuss the TAO/TRITON graphic and my crude estimation of the ONI value that that I develop from that graphic.
The big issue is where will the +6C anomaly water go as it reaches the beaches of Ecuador? To the extent it surfaces it can create convection and impact the Walker Circulation which could then provide positive feedback to this El Nino. But that warm water might tend to go north or south or both. That is part of the phase out process for an El Nino and that is where we are in the life of this El Nino. It is peaking and will soon begin its decline.
The bottom half of the graphic is not that useful in terms of tracking the progress of this Warm Event as it simply shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event and you can see that the cooler water is not making it to the surface to the east along the coast of Ecuador. However, one is beginning to see possibly a slight increase in the slope of the thermocline and the increase in that slope would be the final change as the El Nino dies. .
In the upper graphic, notice the boundary of the 1.5C plus water temperature anomaly (which is now the 1.0C plus water temperature anomaly) is now close to 170W and moving towards the East. That is why I believe the ONI will soon peak and begin to decline. We shall see. There could be another Kelvin Wave forming and there is the issue of how the Walker Circulation might extend the life of this Warm Event. In this regard you might want to read the following post. A key graphic from that post which is a standard graphic is below.
The problem with the above graphic is that it represents the ideal case. You can see the uniform nature of the cells/loops which are areas of rising air and convection (precipitation) and areas where the warm air subsides. Where the air is rising that is an area of low pressure and where the air is subsiding those are areas of high pressure. Things always have to equalize. But the pattern is not always as shown. I believe that in the 1997 El Nino there was a giant Kelvin Circulation that extended from the Pacific to the Indian Ocean not the two cells shown above. So the general case and the variations are important. That is why it is important that we differentiate between Modokis and Traditional El Ninos which have different Walker circulations. This is a good article on the 1997 Super El Nino. I am not in any way suggesting that this El Nino is at all like the 1997/98 El Nino but simply pointing out that the details of each Warm Event are different and that we can not just group them all together and expect to make sense of things.
Back to the TAO/TRITON graphic below, notice the the Warm Event is no longer symmetric around the Equator but tends to be substantially north of the Equator. I am not prepared to explain that but one can see that the entire Pacific is kind of shifted north. It may be related to the Bermuda High but it could be many other factors. I am not qualified to tell you how this will impact our weather. We will observe it together. It clearly impacts the details of the Walker Circulation and the Hadley Circulation also.
For my own amusement, I thought I would recalculate the ONI again as I have been doing recently. To refine my calculation I have totally changed my approach and rather than having the anomalies be the way I organized the data, I have divided the 170W to 120W ONI measuring area into five subregions (that I have designated A through E) and have mentally integrated what I see below and recorded that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions. So now I am applying more subjectivity but it should produce a better estimate.
So as of Monday July 6 in the afternoon working from the July 5 TAO/TRITON report, this is what I calculated which is basically the same as my calculation last week although the patterns of the anomalies have been changing around quite a bit but the changes have been cancelling each other out. :
My estimate of the Nino 3.4 ONI is again 1.46. NOAA has today reported the weekly ONI as again being 1.4 I think that is the third week in a row. Nino 4 has now declined to 1.0. You can already see (in my calculation table) the gradient from West to East that has formed with the higher values in the East and the Western part of the Zone having a smaller anomaly which I believe will soon decline slightly.
Here is another way of looking at it:
This Hovmoeller shows a lot of useful information. I could copy it into MSPaint and draw some lines on it but then it would not auto-updates so I do not wish to do that. But take a lot at 140E 160E, 165E, 180 (The International Date Line), 120W and 90W. Remember reading from top to bottom one is reading the earlier times to the more current times. So you can see how this Warm Event started at 140E, has moved to 160E and then to 165E and lately you can see continued movement towards 180, which it has now reached, but very slowly. You can especially see the impact east of 90W where the Kelvin Wave is crashing into Ecuador. Also more warmer water has expanded towards 120 W. The eastern progress of this Kelvin Wave has been slower than I had anticipated but now appears to be speeding up. The formation of the second part of the Kelvin Wave or a second Kelvin Wave if you prefer has extended the time during which the Kelvin Wave has been impacting the Equator. Leaving aside the SOI issue which until the past two weeks was no longer consistent with an El Nino, but has come to life perhaps just temporarily, this is clearly an El Nino type sea-surface temperature (SST) pattern right now. But to me it seems to be a pattern that will play out as it does not appear to be going to be reinforced.
You will not see the ONI decline until the warm water over at 180. The International Date Line, has moved to 170W. Until then, the ONI could easily continue to rise but probably not by very much although some models are predicting it will peak at about 2.0. Once the warm surface water no longer extends west of 170W the ONI should begin to decline.
The View From Australia
And here is the discussion.
And the IOD
Pulling it All Together
We are in El Nino conditions now. It is probably influencing the IOD to tend towards being positive thus providing a double whammy for parts of Asia and Australia. The length and intensity of this El Nino is still not clear mostly in terms of whether or not it will extend into the early part of 2016. All the computer models predict that it will last longer than my mental model suggests to me. The disagreement is in terms of a couple of months but a couple of months makes a difference in terms of agriculture and other economic impacts. We may or may not have a Pacific Climate Shift as the PDO+ may be simply related to the Warm Event (and quite frankly at this point appears to be). But for now we do have PDO+. The AMO being an overturning may be more predictable so the Neutral status moving towards AMO- is probably fairly reliable but not necessarily proceeding in a straight line. So none of this is very difficult to figure out actually if you are looking at say a five-year forecast.The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report which you can get to below. It includes decade by decade predictions through 2050. Predicting a particular year is far harder. But we are beginning to speculate on the winter of 2016/201 which I believe will tend to be ENSO Neutral. One thing is fairly certain for the U.S. it will be less wet and warmer than the winter of 2015/2016 which will be quite wet and cool.
Click Here for the Global Economic Intersection Weather and Climate Report. Page II where you will find:
My Editor tells me that he will show me how to create a Table of Contents for Part II to make it easier to navigate.
Click Here for Page III which deals with Global Warming.
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