posted on 05 April 2016
Written by Sig Silber
NOAA has issued their Updated Outlook for April. The month of April is forecast to be very different for the first half than the second half. There is always variability within a month but in this case NOAA has emphasized in their discussion the projected changes throughout the month. We cover that aspect of the Update plus a number of other issues including more evidence that a climate shift is likely either relatively immediately or within a couple of years.
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 Subseasonal High-Frequency Cycle (click here to read) has been discovered. Relax, it is not poised to create a heat wave right now. But it is worth reading.
NOAA has as usual issued an update for the month following the last day of the prior month. This update was issued on March 31 and we will discuss that first by comparing the Updated Outlook to the Early Outlook issued on March 17.
Here is the Early Outlook for April Temperatures issued on March 17, 2016.
Updated Temperature Outlook Issued on March 31, 2016
April Early Precipitation Outlook Issued on March 17, 2016
Updated Precipitation Outlook issued on March 31, 2016
Below is the very well written discussion issued with this update.
Sometimes it is useful to compare the present month outlook to the three-month outlook
April plus April - May - Jun Outlook
One can mentally subtract the April Outlook from the three-month Outlook and create the Outlook for the last two months in the three-month period namely May and June 2016. When I do that, I deduce that May and June will have:
One has to keep in mind that we are now subtracting an April Map issued on March 31 from a March 17 three-month map so it is less reliable than the exercise we went through two weeks ago. We are assuming that the three-month outlook issued on March 17 would not change if it was released today. The results in the box above might be an indication of how May and June will differ from the three-month outlook or it might alternatively indicate how the three-month outlook might be modified if issued today. Because the discussion of the Updated Outlook for April addresses recent model projections, it did not seem reasonable to me to draw conclusions about May and June precipitation by subtracting the April Outlook from the three-month outlook. That was a judgment call on my part.
Let's 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 April as a whole as this MJO cycle appears to be weak and the forecasts of phase changes are contradictory. The MJO is thought by some to be relatively unimportant during the winter but perhaps a strong El Nino increases the relevance of the MJO. It has had significant impacts this winter but the impact on April is not likely to be very noticeable. It probably will be more of a factor in the Summer.
Notice the Northern Pacific is 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. I am trying to see if I can discern a change in pattern towards lower latitudes for storms arriving from the Western Pacific but so far I do not see that in this animation.
As I am looking at the below graphic Monday evening April 4, I again see a northerly displaced weather pattern with storms which originated in the Pacific about to come on shore in the Southern Tier. 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 March 29. 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 - 10 Day Outlook
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 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 AMJ Outlook and the recently updated Outlook for the single month of April and then discuss the 8 - 14 day Maps and the 6 - 14 Day NOAA Discussion within that framework.
First - Temperature
Here is the Three-Month AMJ Temperature Outlook issued on March 17, 2016:
Here is the Updated Outlook for April Temperatures issued on March 31, 2016.
Below are the current 6 - 10 Day and 8 - 14 Day Temperature 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 all winter as the patterns are moving from west to east fairly rapidly.
6 - 10 Day Temperature Outlook
8 - 14 Day Temperature Outlook
Looking further out.
Now - Precipitation
Here is the three-month AMJ Precipitation Outlook issued on March 17, 2016:
April Updated Precipitation Outlook Issued on March 31, 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 all winter as the patterns are moving from west to east fairly rapidly.
6 - 10 Day Precipitation Outlook
8 - 14 Day Precipitation Outlook
Here are excerpts from the NOAA discussion released today April 4, 2016. It covers the full nine-day period and this week I have shown both the 6 -10 Day and the 8 - 14 Day Maps.
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 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 although I was forced to last week because the set of analogs I wanted to use was only partially available last week. This first set which is what I am using today applies to the 5 and 7 day observed pattern prior to today. The second set which I am not using (but used last week) relates to the forecasted outlook 6 - 10 days out correlation with 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 and I find it so.
One thing that jumped out at me right away was the spread among the analogs from Mar 24 to Apr 16 which is just over three weeks. It suggests that the prior week conditions are highly correlated with weather patterns which in the past occurred over a fairly narrow range of dates as shown. There are again this time zero El Nino Analogs, six ENSO Neutral Analogs and two La Nina Analogs suggesting that El Nino is again not in control over our weather for the next 6 - 14 Days or perhaps more accurately the forecast best correlates with periods of time when ENSO was neutral or in the La Nina state. The 1990 and 1994 analogs are quite interesting as they are before and after a wet period. It raises some questions about the forecast shift to La Nina.
The phases of the ocean cycles in the analogs point clearly towards McCabe Condition B. It is a stretch to conclude that 6 - 14 Day Outlook is consistent with McCabe Condition B. 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 inactive phase of the MJO changed to the Active Phase and you see this in the El Nino-ish SOI readings. But local conditions in Tahiti are also involved and may not be directly related to the MJO. The 30-day average, which is the most widely used measure, as of April 4 is reported at -3.99 which is not really a reading that is associated with an El Nino (usually required to be more negative than -8.0 but some consider -6.0 value good enough). The 30 day average was impacted by some very low SOI values which occurred five weeks ago dropping out of the average. So it is difficult to really interpret right now. The 90-day average remains in El Nino territory at -14.43 a bit weaker than last week. 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 somewhat 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 continue to see a moderating trend in the SOI from here on with the possible exception of the current impact of the MJO and continued local stormy conditions in Tahiti. If the reference point is the dateline, the MJO may begin to change to the Inactive Phase this week. It is not likely to have much impact on the SOI but may keep it in El Nino territory for another couple of weeks or so.
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.
SOI as a Precipitation Prediction Tool
Here is a graphical presentation of the SOI values.
If you assume there has been sufficient recent history to show that that the SOI is rising (my interpretation not the interpretation of Queensland), then the Queensland Model would provide this forecast for precipitation.
In reality we only have had one month of rapidly rising SOI. And this is a model that only uses one variable to make its prediction but it is interesting and perhaps is more reliable than one might expect.
Low-Level Wind Anomalies
Here are the low-level wind anomalies. We recently for the first time started to see Easterly anomalies, the blue area at the bottom of the Hovmoeller graphic. But have again switched to Westerly anomalies probably related to the more Active Phase of the MJO. This is likely to change back soon to Easterly anomalies which has a big bearing on the rate of demise of this 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 is being 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 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.
Top Graphic (Anomalies)
The above graphic 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.
Bottom Graphic (Absolute Values which highlights the Thermocline)
The bottom half of the graphic may soon become more 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.
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 ten weeks 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, 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. Note the 3C anomaly no longer exists. The 2.5C anomaly also no longer exists as of mid-week. As this El Nino decays I am including the less warm anomalies in the table below.
* The western portion of the anomaly is all South of the Equator and the above graphic only shows where the anomalies are on the Equator. The Eastern portion has now extended back to 135W and is again in the ONI Measurement Area.
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 April 4, in the afternoon working from the April 3 TAO/TRITON report, this is what I calculated.
ONI Recent History
The official reading for Jan/Feb/Mar is now reported as 2.0. I have discussed before the mystery of how the 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. You can easily see how the intensity peaked in November 2015, declined in December and then declined substantially in late February and continues to decline.
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 90 Days.
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.
El Nino in the News
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 some of the models seems increasingly likely to be a La Nina.
The below is the CPC/IRI forecast issued on March 17, 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 the models 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.
What is really strange is the NOAA's own model has until recently disagreed with their official IRI/CPC Model. What is that all about?
This is an interesting graphic.
The problem is the poor fit with the data. Here is the full article by Anthony G Barnston a consultant to NOAA who posts on Climate.gov. I have done my own analysis which I published in a previous issue of this weather column. Some of the researchers attempt to segment the data by the magnitude of the ONI value. It seems that this makes a difference. I have provided the links to some of these articles but other than what is posted on Climate.gov I am reluctant to extract graphics from the works of others so I provide the link to their full article. Generally they would give me permission and I think I have permission from one of the authors to use his material but it gets complicated for me as I am spontaneous and I am writing this section of my report early Sunday Morning and I have a 9pm Monday deadline so it is difficult for me to routinely attempt to get permissions so I just provide a link and an explanation of why readers may want to visit that link.
This is a topic that is getting a lot of attention.
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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