posted on 17 May 2016
Written by Sig Silber
The overall pattern in the Pacific has changed to a summer pattern. The zonal movement of weather patterns from west to east has slowed down and and, after one more Pacific storm, will be replaced by mostly south to north movements. El Nino is essentially dead (RIP) and has been assigned (by me) a life expectancy of one week. We will now increasingly have typical Summer Weather which varies depending on where you live. But we wonder about next Winter so both topics will be discussed today.
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.
Last week I briefly discussed in the paragraph above the "Landing Graphic" the physical basis for the phases of ENSO which I prefer to look at as a battery. This is important not just for impacts associated with this medium frequency cycle but also the way it interacts with Global Warming, storing heat in the ocean during the La Nina Phase and releasing the heat to the atmosphere during the El Nino Phase.
The way that works is pretty simple. During an El Nino, the Warm Pool is spread out so the surface area of water that is prone to evaporation is larger. Thus there is more convection in the Pacific and this transfers heat first to the water vapor and later to the clouds. You will see this in the data for average Atmospheric and Land Temperature during this El Nino. It has increased.
But now I want to briefly discuss El Nino and La Nina impacts. I hesitate to do this because I have been pretty consistent in making the point that all El Ninos and all La Ninas are different. So the below is conceptual ONLY. You can not take it to the bank.
Comparing El Nino to La Nina
The first two graphics, and there are many versions of these graphics but the above are very colorful, show how the Jet Stream tends to be further south during an El Nino (not this past winter). Notice the Aleutian Low in the El Nino graphic. The Blocking High in the La Nina pattern is reminiscent of summer weather but it is further off shore than a typical summer so it allows Pacific storms to enter the U.S. via the Northwest.
Now we take a look at the Walker Circulation which is where the warm water causes evaporation and convection (cloud formation) and where these clouds tend to drop their precipitation which creates downwards air movements. The colors also reveal the location of warmer than climatology and cooler than climatology Sea Surface Temperatures (SST) which are used to define the pattern. Pay special attention to the water along the Equator.
It is difficult to see the difference between the La Nina (above) and Neutral conditions (below) but you should pay attention to the more pronounced (darker - thicker arrows) convection zone in the El Nino state as compared to the Neutral state and similarly the stronger subsidence zone in the La Nina state. Subsidence tends to warm and dry air masses.
It is a lot easier to see the different between Neutral and El Nino as the pattern tends to reverse with Convection Zones converting to Subsidence (drying) Zones. This winter the Convection Zone was further west than usual and I have mentioned that almost every week.
Let's Now Focus on the Current (Right Now to 5 Days Out) Weather Situation.
A more complete version of this report with daily forecasts is available in Part II. This is a summary of that more extensive report. Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks will take you directly to that set of information but it may take a few seconds for your browser to go through the two-step process of getting to Page II and then moving to the Section within Page II that is specified by this link.
First, here is a national animation of weather front and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at the link provided above.
The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implemented by color coding.
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.This graphic auto-updates so when you look at it you will see NOAA's latest thinking. The speed at which these troughs and ridges travel across the nation will determine the timing of weather impacts. This graphic auto-updates I think every six hours and it changes a lot.
The MJO is not likely to have much of an impact for the month of May as a whole as this MJO cycle appears to be weak and the forecasts of phase changes are contradictory. The MJO has had significant impacts this winter but the impact on May is not likely to be very noticeable.
Notice the Northern Pacific is now much less like a giant anticyclone with clockwise motion so that which gets sent west due to El Nino is to some extent returned to North America but at higher latitudes. Everything is now moving east.
As I am looking at the below graphic Monday evening May 16, I see a dry Southwest and wet East pattern and the continued northerly displacement of the overall storm track. But the local forecasts call for that storm track to drop down and cross New Mexico tomorrow. One can already see on this graphic (and out the window where I am finalizing this report here in Santa Fe New Mexico) part of the storm swinging down into New Mexico. As we move into a Summer Pattern, the concept of a storm track west to east becomes less relevant and we focus more on south to north movements i.e. the Monsoon in the Southwest and Tropical Storms in the East and Gulf of Mexico. This graphic updates automatically so it most likely will look different by the time you look at it as the weather patterns are moving from west to east.
Below is an analysis of projected tropical hazards and benefits over an approximately two-week period. This graphic is scheduled to update on Tuesday and I am reading the May 10, 2016 Version and looking at Week 2 of that forecast.
Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 6 (the Day 3 forecast is available on Page II of this Report). This graphic also auto-updates.
Looking at the current activity of the Jet Stream
And here is the forecast out five days.
To see how the pattern is projected to evolve, please click here. In addition to the shaded areas which show an interpretation of the Jet Stream, one can also see the wind vectors (arrows) at the 300 Mb level.
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.
Click here to gain access to a very flexible computer graphic. You can adjust what is being displayed by clicking on "earth" adjusting the parameters and then clicking again on "earth" to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns.
And when we look at Sea Surface anomalies below, we see a lot of them not just along the Equator related to El Nino.
Below I show the changes over the last month in the Sea Surface Temperature (SST) anomalies.
6 - 14 Day Outlook Plus the Week 3-4 Experimental Forecasts
Now let us focus on the 6 - 14 Day Forecast for which I generally only show the 8 - 14 Day Maps. The 6 - 10 Day maps are always available in Part II of this report but in the Winter and Spring I often show both maps as the forecasted weather patterns change during that nine day period.
To put the forecasts which NOAA tends to call Outlooks into perspective, I am going to show the three-month MJJ Outlook and the recently updated Outlook for the single month of May and then discuss the 6 - 10 Day and 8 - 14 Day Maps and the 6 - 14 Day NOAA Discussion within that framework.
First - Temperature
Here is the Three-Month MJJ Temperature Outlook issued on April 21, 2016:
Here is the Updated Outlook for May Temperatures issued on April 30, 2016.
Below are the current 6 - 10 Day and 8 - 14 Day Temperature Outlook Maps which will auto-update daily and thus be current when you view them. It covers the nine days following the tail end of the current week. I have included both today and probably will continue to do that as long as the patterns are moving from west to east fairly rapidly. I have also included the experimental Week 3 and 4 Outlook. The Week 3-4 Experimental Outlook updates weekly on Friday. Notice the Week 3-4 Experimental Outlook has fewer levels of probability starting with 50%.
6 - 10 Day Temperature Outlook
8 - 14 Day Temperature Outlook
Looking further out.
Now - Precipitation
Here is the three-month MJJ Precipitation Outlook issued on April 21, 2016:
Updated Precipitation Outlook for May Issued on April 30, 2016
Below are the current 6 - 10 Day and 8 - 14 Day Precipitation Outlook Maps which will auto-update and thus be current when you view them. It covers the nine days following the tail end of the current week. I have included both today and probably will continue to do that as long as the patterns are moving from west to east fairly rapidly. I have also included the experimental Week 3 and 4 Outlook. The Week 3-4 Experimental Outlook updates weekly on Fridays. Notice the Week 3-4 Experimental Outlook has fewer levels of probability starting with 50%.
6 - 10 Day Precipitation Outlook
8 - 14 Day Precipitation Outlook
Here are excerpts from the NOAA discussion released today May 16, 2016.
Some might find this analysis interesting as the organization which prepares it looks at things from a very detailed perspective and their analysis provides a lot of information on the history and evolution of this El Nino.
Analogs to the Outlook.
Now let us take a detailed look at the "Analogs" which NOAA provides related to the Outlook.
I prefer the set of analogs that relates 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. But the NOAA system for generating those pre-forecast analogs is not working. They publish a second set of analogs which relates the 6 - 10 Day Outlook to previous occurrences of that weather pattern and similarly for the 8 -14 Day Outlook. So that is what I am using today. It is explained here and here. I do not like my work being doubled so I decided to just use the second set of analogs which corresponds to Day 11 of the Outlook. In my mind that set of analogs tells you nothing (zilch) about the reliability of the forecasts but is helpful in predicting the outlook for the subsequent time periods. That is interesting also. I am also presenting them today in the order that they are provided which means the ones at the top have the highest level of correlation with the forecast and thus are more reliable for forecasting future time periods.
One thing that jumped out at me right away was the spread among the analogs from May 11 to June 10 which is a full month. Day 11 of this Outlook (it may change by the time you view it) is May 27. So eight out of ten of these analogs are later than the centroid of the forecast suggesting to me that summer is coming unusually quick this year. If you look at the first five analogs which are the ones with the highest correlation it is not an enormous difference but a little less than a week advanced. There are this time three El Nino Analogs, six ENSO Neutral Analogs and one La Nina Analog suggesting indecision or that we are now beyond the point where the Phase of ENSO is very important.
The phases of the ocean cycles in the analogs are inconclusive but slightly favor PDO Negative AMO Positive if you ignore the combinations but simply add up the numbers of PDO+ (6 out of 10) and AMO- (6 out of 10). This is somewhat consistent with the forecast. The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. Water Planners might usefully pay attention to the low-frequency cycles such as the AMO and the PDO as the media tends to focus on the current and short-term forecasts to the exclusion of what we can reasonably anticipate over multi-decadal periods of time.
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.
With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not as easily interpreted. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.
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 moving/running average and the third is the 90 day moving/running average.
The 30-day average, which is the most widely used measure, as of May 16 is reported at -8.99 which is again associated with an El Nino (usually required to be more negative than -8.0 but some consider -6.0 value good enough). It is quite a bit weaker (less negative) this week. If there were one or two more weeks of such readings, the SOI would move into ENSO Neutral Territory. The 90-day average remains in El Nino territory at -12.93. Usually but not always the 90 day average changes more slowly than the 30 day average but it depends on what values drop out. The SOI continues to be indicative of an El Nino Event in progress but it is pretty much passed the time of year where it is very meaningful re El Nino development. I believe we will see a moderating trend in the SOI from here. It kind of looks like the SOI is about to signal the end of this EL Nino just as the ONI is about to do the same.
The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource.
Low-Level Wind Anomalies
Here are the low-level wind anomalies. We now see light easterly anomalies which are probably an indication of both a lack of MJO activity and the death of the El Nino.
And now the Outgoing Longwave Anomalies which tells us where convection has been taking place.
Let us now take a look at the progress of Kelvin Waves which are the key to the situation. From the earliest to the most recent they can be named #1 through #5. Kelvin Wave #1 has now been pushed off the top of this graphic as more recent information is added at the bottom.
One should keep in mind that for a new Kelvin Wave, the period of time from initiation to the termination of impacts is about six months. So when you have four or five this winter six in a row, the pattern of impacts on different indices and geographic areas becomes quite complex. It is further complicated as you can see above because the Kelvin Waves do not necessarily originate at the same location i.e. longitude.
We are now going to change the way we look at a three dimensional view of the Equator and move from the surface view to the view from the surface down. This El Nino appears to be fading slowly from west to east. The real decline will be from east to west.
Current Sub-Surface Conditions. Notice the lag in getting this information posted so the current situation may be a bit different than shown.
And now the pair of graphics that I regularly provide and which as I publish are currently able to be accessed from the NOAA website: I was however expecting to have a May 13 update of this graphic to report on today.
The above pair of graphics showing the current situation has an upper and lower graphic. The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters.
The bottom half of the graphic (Absolute Values which highlights the Thermocline) perhaps is a now equally useful in terms of tracking the progress of this Warm Event as it converts to ENSO Neutral and then La Nina.
Here are the above graphics as a time sequence animation. You may have to click on them to get the animation going.
Let us compare the situation as reported on October 4 to the most recent graphic. Remember each graphic has two parts the top part is the average values, the bottom part is those values expressed as an anomaly compared to the expected values for that date. Generally I am mainly discussing the bottom of the pairs of graphics namely the anomalies
First the October 4 version which I am providing for purposes of comparison. I "flash froze" the daily value that day so that it would not auto-update.
And then the December 14 version which I also "flash froze" to stop it from updating.
And then the current version of the TAO/TRITON Graphic.
The 3.5C anomaly is no longer visible. Neither is the 3.0C anomaly or the 2.5C anomaly or the 2C anomaly. The 1.5C anomaly only exists in the Nino 3.4 Measurement Area south of the Equator and may soon be too far south to be counted. So the maximum anomalies (which do not appear everywhere) have declined by a full two and one half degrees Centigrade almost everywhere. This means that if one is attempting to mentally estimate the daily ONI, an approach would be to make an initial estimate of the midpoint of the 1C to 1.5C anomaly or 1.25C and subtract the reductions from there where the anomaly is less and if appropriate, and it was not this week, add back in the area south of the Equator. What I have just described is not exactly the approach I use in my calculation below but it does provide a quick way to get a feel for the current strength of this El Nino. There is actually shading in the TAO/TRITON Graphic that might allow one to try to refine estimates a bit more than the contour lines but I rely on the contour lines. This El Nino is almost gone.
And an earlier but recent reference point close to the peak of this El Nino re the bottom half of the TAO/TRITON Graphic. You can certainly see the difference that three months makes.
The below table tracks the changes. It only addresses the situation right on the Equator so visually the TAO/TRITON graphic contains more information. But the below table turns visual information into quantitative information so it may be useful. The degrees of coverage shown in the rightmost two columns shows that the extent of the warm water directly on the Equator has been reduced in recent weeks. The way I constructed the table for the rows related to a Warm Event, the 1.0C anomaly as an example includes all water warmer than 1.0C so the 1.5C anomaly is included within it as well as the 2.0C anomaly which you can tell by the way I recorded the westward and eastward coordinates. I could have constructed this table in a different way. And Indeed for the cool layers the -.5C anomaly includes all water as cool as -5C or cooler. I am not sure if I have figured out the best way to record the Neutral water areas. The point of the exercise is to show how over time the warm anomaly for actual or potential El Nino events has expanded or shrank and the cool anomaly for actual or potential La Nina events has expanded or shrank.
Note the 3C anomaly, 2.5C anomaly, 2.0C anomaly, 1.5C anomaly and even the 1.0C anomaly no longer exists along the Equator. As this El Nino decays I am including the less warm anomalies in the table below.
I calculate the ONI each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W ONI measuring area into five subregions (which I have designated from west to east as A through E) with a location bar shown under the TAO/TRITON Graphic). I use a rough estimation approach to integrate what I see below and record that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions. So as of Monday May 16, in the afternoon working from the May 15 TAO/TRITON report, this is what I calculated.
ONI Recent History
The official reading for Feb/Mar/Apr is now reported as 1.6. I have discussed before the mystery of how the Nino 3.4 (ONI) CFSv2 values above get translated into the ERSST.v4 values shown below and if NOAA feels that working with two sets of books is a good way to operate, who am I argue. Many businesses do the same thing. As you can see this El Nino peaked in NDJ and is now declining and depending on what system you use it is either the 2nd or 3rd strongest El Nino since modern records were kept which is considered to be 1950. You could argue for it being #1 based on a week of readings but few are buying that argument. Still #2 or #3 means it is one of the strongest ever based on the way these events are measured. I will be writing more about that soon in a separate article. I believe the measurement system is inadequate re being useful in forecasting Worldwide weather impacts.
Is this El Nino a Modoki?
It did not evolve as a Modoki unless you consider it to be a continuation of the Faux El Nino Modoki of 2014/2015 which is a possible interpretation. But the Walker Circulation appears to be much like that of a Modoki. These graphics help explain this.
Although I discussed the Kelvin Waves earlier, now seems to be the best place to show the evolution of the subsurface temperatures.
SST Surface Anomaly Hovmoeller
Here is another way of looking at it: Unlike the Upper Ocean Heat Anomaly Hovmoeller (I call it the Kelvin Wave Hovmoeller) which takes an average down to 300 meters, this just measures the surface temperature anomaly. It is the surface that interacts with the atmosphere and causes convection and also the warming and cooling of the atmosphere. A major advantage of the Hovmoeller method of displaying information is that it shows the history so I do not need to show a sequence of snap shots of the conditions at different points in time. Nevertheless this Hovmoeller provides a good way to visually see the evolution of this El Nino and later track its demise.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
Below are snapshots of 30 Day temperature and precipitation departures over the life of this El Nino. The end date of the 30 day period is shown in the graphic. It is a way of seeing how the impacts of this El Nino have unfolded.
Lets take a look at the combined results for the first three months of 2016: January, February and March.
And here is the April (30 day) graphic.
I realize this is a lot of graphics but one needs to look at the history of an event to assess it. As you can see, so far we are not having the expected El Nino Impacts in CONUS.
Here is the ninety day picture for February, March, and April.
And here is the graphic from last week which added a week and removed the seven earliest days so it is a 30 day analysis through May 7, 2016
El Nino in the News
Global Warming in the News
Nothing to report this week.
Putting it all Together.
This El Nino has peaked in intensity and is now in rapid decline. We are beginning to speculate on the winter of 2016/2017 which now according to most of the models seems increasingly likely to be a La Nina.
The below is the CPC/IRI forecast issued on May 12, 2016. It is important to remember that the first report in each month is based on a survey of meteorologists and the second report later in the month is based on the analysis of the forecast models. It is a minor difference but a difference.
We have suggested that it is possible that some of the models and in particular NOAA's model will be wrong about how fast the Eastern Pacific Warm Pool moves back towards its La Nina location and it may well be that next winter will be more of a Neutral year or even have some characteristics of an El Nino Modoki and thus be wetter than a typical year as the Warm Pool may still be more in the Central Pacific than shifted all the way west to its La Nina position.
I now have the May 1 Run of the JAMSTEC Model.
It is forecasting a moderate La Nina for next winter and continuing as a La Nina or Neutral with a La Nina tendency for the subsequent winter. That could be the signal for the Pacific Climate Shift.
Here is the Australian Model. It has not updated since I presented it last week but I will be including it every week now as tracking the change in phase of ENSO is the most important weather issue for our Planet right now.
It does not extrapolate as far into the future as the JAMSTEC model. It is somewhat similar to the NOAA model but seems to be less certain that we will have a La Nina rather then ENSO Neutral with a La Nina tendency.
Forecasting Beyond Five Years.
So in terms of long-term forecasting, none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast. The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.
TABLE OF CONTENTS FOR PART II OF THIS REPORT The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page II where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
A. Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks (Usefully bookmarked as it provides automatically updated current weather conditions and forecasts at all times. It does not replace local forecasts but does provide U.S. national and regional forecasts and, with less detail, international forecasts)
1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)
D. Reserved for a Future Topic (Possibly Predictable Economic Impacts)
TABLE OF CONTENTS FOR PART III OF THIS REPORT - GLOBAL WARMING WHICH SOME CALL CLIMATE CHANGE. The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page III where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
D2. Climate Impacts of Global Warming
D3. Economic Impacts of Global Warming
D4. Reports from Around the World on Impacts of Global Warming
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