posted on 28 September 2015
Written by Sig Silber
Today we compare the NOAA and JAMSTEC forecast through March - April - May 2016. The JAMSTEC forecast for CONUS is colder and wetter than NOAA's forecast. The JAMSTEC information identifies areas of the World with significant deviations from climatology (normal). Whether or not the actual weather works out as either of these forecasts suggests is an open question. Over the next two weeks, the NOAA forecast has, according to NOAA a low level of confidence and the analog analysis in this report suggests why.
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.
NOAA issued an updated Seasonal Outlook on September 17. The JAMSTEC (Japanese) analysis is also available. Let us compare them.
First let's take look at the ONI forecasts which is the most widely available measure of the strength of an El Nino (or La Nina) and is the deviation of the sea surface temperature from climatology (normal) in a small part of the Eastern Pacific along the Equator considered to be the best place to assess the strength of an ENSO phase whether it be El Nino, ENSO Neutral, or La Nina.
First the NOAA forecast of conditions in the Nino 3.4 area which defines the ONI Index:
OMG there are two different versions of the model results. There is this one:
And below is another version (and the version below is the one that NOAA shows in their weekly ENSO Report so I am assuming that it is the one that they want us to use) . I am not sure of the specifics of the difference but the results are modified in some way presumably to make them more accurate. I think it has to do with the base used to establish "Climatology" which is usually defined as conditions from 1981 - 2010 (not sure why it says 1982 - 2010). But the Equator has been experiencing a warming trend thus a thirty-year average may overstate warm anomalies. So, to me, reading the legend in the graphic below It looks like the base was adjusted to 1999 - 2000 reflecting the steady rise of temperatures in the Pacific. It is possible that there is also an adjustment for the variation in the model results for the multiple members of the ensemble but I do not know how that would work given that they still refer to the mean of the different forecasts of the members of the ensemble. So I can not tell you exactly why the model results below differ from the model results above.
Curiously this version below has kind of a camel-back or is it a staircase with a decline in October and then either a slight increase or steady for the three-month period OND. The uncorrected version shows the peak in OND. This is perhaps a minor difference; the major difference being the lower level of the Nino 3.4 Anomaly in the below version of the model. I believe that the below adjusted version of the CFSv2 Nino 3.4 Anomaly Forecast is what NOAA wants us to use but I do not think (not sure) that JAMSTEC or Australia apply similar adjustments. So I am not sure exactly which model result to use to compare but fortunately it does not matter very much as their pattern is similar.
And here is the JAMSTEC forecast of the ONI.
At this point it looks like the JAMSTEC model forecasts the ONI to stay higher perhaps a month or two longer than NOAA and you will see how that is reflected in their temperature and precipitation forecast. The discussion that relates to this model forecast was just issued.
Now I will compare the two forecasts using three time periods: Short Term, Medium Range, and Long Term
SHORT TERM (September - October - November for JAMSTEC and October - November - December for NOAA. - I could have used the old SON NOAA maps but that would not seem to have been useful. JAMSTEC only issues three maps which I have called "short term", "medium range" and "long term".
Sea Surface Temperatures.
Starting with the NOAA results (and notice that they show Africa twice which can be confusing but allows Africa to be more easily considered in the context of the oceans that surround it):
And now the JAMSTEC Sea Surface Temperature Anomaly. It was recently issued but an October - November - December OND map comparable to the NOAA map would be more useful. I could have compared the JAMSTEC SON maps with the NOAA SON maps issued last month but decided that would not be useful. The difference of one month in the three-month average is not critical.
They look fairly similar if you can get by the garish colors used by the NOAA graphic artists. I find the JAMSTEC graphics easier to look at. I am curious about the cold anomaly that NOAA shows for the Equator in the Atlantic. There also appears to be a difference with respect to the waters off of Japan with JAMSTEC projecting cool and NOAA warm.
Now let's take a look at the Temperature forecasts for that period starting with NOAA:
And then JAMSTEC:
For CONUS, JAMSTEC is forecasting that the colder than climatology area will extend much further north. NOAA does not cover the rest of the world. In the JAMSTEC map (and the discussion above which was provided by JAMSTEC) you can see that most of world is projected to be warmer than climatology with the U.K., Northeastern China, Korea, and Argentina being notable exceptions. Given that there is Global Warming and the forecasted values are being compared to a base that may not fully reflect the warming which has occurred, any cold anomalies are especially significant.
Now let us look at Precipitation again starting with the NOAA map.
And here is the JAMSTEC Precipitation Map.
The NOAA forecast and JAMSTEC forecast are pretty similar for that period with regards to CONUS but JAMSTEC extends the wet area into the Northeast. Interesting features of the JAMSTEC map outside of CONUS include dry conditions in Central and Northern Brazil, Panama, parts of India, parts of Australia, and the Mediterranean.
MIDRANGE (December - January - February)
Starting with Sea Surface Temperature Anomalies and beginning with NOAA:
And then JAMSTEC:
JAMSTEC is still showing El Nino into 2016. But it is looking a bit more Modoki-ish in terms of the connection of the warm water with the South American Coastline. Notice the less intense coloration off the Coast of Ecuador and Peru in both the NOAA and JAMSTEC maps but with some differences in the pattern of the gap. But the AMO is more Negative and the PDO is more clearly defined in the JAMSTEC map. The NOAA map again seems to be showing a strong cold anomaly along the Equator in the Atlantic Ocean. I wonder what that is about. They seem to have different opinions on the ocean temperature anomalies off of the coast of West Africa.
Now let us take a look at Temperature and again first NOAA:
And then JAMSTEC for the same three months
JAMSTEC now is more aggressive at forecasting widespread colder than climatology conditions for CONUS as compared to NOAA. JAMSTEC is showing an expansion of cold for Northern Europe: a negative NAO perhaps. Both JAMSTEC and NOAA show Alaska as still being warmer than climatology which suggests the Aleutian Low will be strong and positioned to direct warmer air over Alaska.
Now Precipitation and again staring with NOAA:
And then JAMSTEC.
Looks like for both JAMSTEC and NOAA the precipitation impacts of the El Nino begin to fade away slightly in this time frame with NOAA being a bit more definitive. The JAMSTEC maps show increasing drought for Australia and continued drought for southwest Africa and parts of Eastern Brazil extending into Central America. Southern Europe is wet corresponding to them being cold. India returns to normal.
LONG RANGE (March - April - May)
And then JAMSTEC:
Here we see a big difference between the JAMSTEC and NOAA forecasts. JAMSTEC is well along to ENSO Neutral in their forecast perhaps pausing and resembling an El Nino Modoki Type II on the way. But the warm water off of the West Coast of North America continues so that it is not clear which of the two will have the most impact on North American weather. It is a bit difficult to reconcile the JAMSTEC map with their SST/ONI forecast which was presented at the beginning of this analysis.
Now let us look at Temperature and again starting with NOAA
And then JAMSTEC
There is some similarity in the pattern but I think overall JAMSTEC is cooler over a larger part of CONUS. Again it is a warm Alaska. But in the JAMSTEC maps parts of Europe remain cool as well as Iran, Afghanistan, Pakistan, Northern China, South Korea, and parts of Argentina.
And finally the Precipitation forecast and again starting with NOAA:
And then JAMSTEC.
For CONUS there is a lot of similarity in the forecasts with JAMSTEC showing a wetter northwest. The JAMSTEC forecast is remarkably wet given their ONI and SST forecasts but that may represent the delay between the ONO declining and the SST pattern shifting a bit into a Central Pacific El Nino and the weather impacts. And of course MAM is somewhat out in the future. South Africa and Eastern Brazil and and parts of Mexico and Scandinavia and parts of Australia and remain dry. There appears to be increasing drought conditions in the Indochina Peninsula and Myanmar (formerly Burma). I am not sure of the significance but the wet area along the Equator splits into two halves which move away from the Equator. You can look at the three maps showing three sets of months which cover the life of this El Nino and you can see the pattern of a wet Equator with dry belts north and south of the wet area and you can see how JAMSTEC projects this pattern to evolve.
The main conclusions relate to the ONI forecasts and the Sea Surface Anomaly forecasts which for both meteorological agencies cover the world. With respect to temperature and precipitation, I can only compare the two for CONUS but also comment on what JAMSTEC is projecting for the rest of the World which I have done for the three time frames: near-term, medium range, and long term. A few general conclusions are that:
Shifting Focus to 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. This link Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks will take you directly to that set of information but in some Internet Browsers it may just take you to the top of Page II where there is a TABLE OF CONTENTS and you may have to wait for a few seconds for your Browser to redirect to the selected section with that Page or if that process is very slow you can simply click a second time within the TABLE OF CONTENTS to get to that specific part of the webpage.
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. You can see the location of the Four Corners area where Utah, Colorado, Arizona, and New Mexico meet. During the summer, there is typically a high pressure system near that area and it is called the Four Corners High. When the Four Corners High is centered directly over the Four Corners area, it creates pretty much a block for the Sonoran Monsoon which only visits its northern neighbor when the highs and lows are located in a way that draws the moist air north.
Small changes in the location of that feature make a big difference in the weather of probably about ten or more states.
This High moves around a lot so by the time you view this report, it most likely it will be located somewhere else which results in a different circulation pattern. The current position as I am finalizing my report was shown way to the south (in the Middle of the Gulf of Mexico) which to some extent is consistent with the seasonal path of that feature as the Monsoon gets long in the tooth. Remember this is the mid-atmosphere High: the short-term location of the Surface High is shown in the above animation and it is in a more normal location but may not be very effective at influencing circulation from Mexico into the Southwest. If you know where the High is, you can always imagine 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 be very very useful. And it auto-updates, I think every six hours. Even without a weather map, you generally can figure it out. Wind to your back, High to your right, Low to your left. You can clearly see the trough along or just west of the Rocky Mountains and also a weak trough coming down from the Great Lakes. Those appear to be the dominant features projected to be determining CONUS weather on Day 7.
Because "Thickness Lines" are shown by those green lines on this graphic it is a good place to define"Thickness" and its uses. You can find a full uk.sci.weather style explanation (thorough) at that link or just remember that Thickness measures the virtual temperature plus moisture content) of the lower atmosphere and is very useful especially in the winter at identifying areas prone to snow and in the summer areas which are going to be hot and humid. Here is a U.S. style explanation of "Thickness" by Jeff Haby who is a valuable source of Haby Hints for anyone who wants an explanation of a meteorological term.
The level of storm activity in the Western Pacific has tapered off quite a bit.
At this time of the year, warm water off of the coast of Mexico, such as from an El Nino or a positive PDO reduces the ocean/land temperature differential and can weaken the Monsoon overall but the cyclones generated by that warm ocean water can enhance the Monsoon for short periods if those cyclones stay close enough to the Mexican coastline. So that is what is being watched now and there seems to be an endless sequence of the storms forming.
But each of these El Nino related tropical storms off the coast of Mexico has the potential, if they are close enough to shore, to introduce moisture into the circulation that enters CONUS and that has been the case this summer but it is sporadic. It also mostly benefits the western side of Mexico and the western reach in CONUS of the Southwest Monsoon but there has been a tendency for some of that moisture to also benefit New Mexico. But overall it has diminished the impact of the Southwest Monsoon as it has cut off any Gulf of Mexico involvement and generally has impacted a smaller number of states than is usually the case. For Mexico, an El Nino is a drought event.
But as shown below there are other storms . One of these storms has been directed out to sea but the following storm, Marty, appears to be poised to have an impact on Mexico and possibly also CONUS but I think it will dissipate in Mexico and not have a major impact on CONUS. But there may be other storms right behind it. .
The graphic below is harder to look at but provides more detail on the water vapor being generated by these storms and the normal summer action of the Southwest Monsoon. It covers a much larger area within CONUS so you can see where the moisture currently is and is going. This graphic is very good at pointing out the divisions between cloudy and not cloudy areas.
As I am looking at this graphic Monday evening, I see a real division between the western and eastern weather systems.
Here is a broader view of projected tropical hazards and benefits over an approximately two-week period. There are two views. One is more focused on the Pacific and one that includes the Indian Ocean and covers Asia more completely. Both graphics auto-update weekly but each updates on a different day of the week so when you look at them both carefully you might see some difference due to the exact day when they were updated. More information can be foundhere. The discussion at that link there may update on Tuesdays. I am not sure.
Looking at the first graphic (and as I am looking at it it is the most recently updated but they will take turns being the most recently updated) what stands out to me, at the time of publication, is the dry conditions in the far north of South America and the area where conditions for the development to cyclones is high off the coast of Mexico but no longer off the coast of Florida and Georgia. It now shows in what NOAA calls Week 1 a wetter area that crosses the northern part of Central America and extends over to the Southeast of CONUS
This graphic below covers a larger part of the world. With this graphic, at the time of publication, you see more activity over by Asia including dry conditions in Indonesia and the Philippines and dry conditions in part of India in what they call Week 1 of their forecast. At the time of publication the above graphic was more current for North and South America. It gets confusing. I realize that.
Below is a 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). We now see something very different than what we have been seeing for a long time and that is perhaps the Aleutian Low returning as one would expect in the winter. The atmospheric pressure systems off the West Coast are complicated and appear in some cases to be forcing the tropical storms moving up the coast off of Mexico inland.
We now need to monitor the Jet Stream to see if it is shifting to the South. This is the forecast out five days.
To see how the pattern is projected to evolve, please click here. The activity still appears to be mostly north rather than south but we are starting perhaps to see that changing a bit with a southern branch of the Jet Stream reappearing for winter and El Nino. Is this the beginning of the shifting to the south of the Jet Stream which one would expect with an El Nino? We will see but it would be reasonable for that to occur now.
And when we look at Sea Surface anomalies we see a lot of them not just along the Equator related to El Nino. But the extent of the warm water off the West Coast appears to be a bit less than recently. The Atlantic has really heated up. But look at the colder water off of the U.K. You can tell a lot from this graphic. The warm anomalies are not evenly distributed around the world. There is more in the Northern Hemisphere possibly related to there being more land in the Northern Hemisphere. So there may be a connection to the ratio of land to water and the heating of the water surface. The warm water off of California is a wild card in the impacts of this El Nino.
This graphic below shows the changes over the past four weeks (ending September 16) as compared to the above graphic which shows the current SST anomalies. Looking at both is helpful in putting the current situation shown above into perspective.
And this week's version of the same graphic showing the changes up to September 23. Of course today is September 28 and you probably will not see this until September 29 but the graphic above this one auto-updates so it is the most current information available. These two graphics (the one above and the one below) are for analysis purposes as they show the changes in the anomalies shown in the graphic above this one.
In both graphics you can see the increasing change in the Nino Area which was not as evident two weeks ago indicating a big change since two weeks ago in that this and the prior graphic are four-week averages. The change in last week's graphic is less than in the prior week indicating that the rate of change has slowed. You can also see that the cool water west of the U.K. has remained colder than climatology but that may have also eased a bit. We again see the warming south of Australia but more importantly west of Australia which has canceled out the IOD for now. We now see less warming in the Atlantic Hurricane Development Area but more just north of South America. Remember these are four-week averages and graphic above the two weekly average graphics is the daily readings which auto-update. You can get a better feel there for the IOD. It is difficult to relate the actuals to the four week changes but it paints a picture. Remember the actuals are anomalies which is the change from climatology (normal) so we are talking in these two bottom two graphics about the change in the change. It is kind of like the first derivative of the "anomalies" which to confuse things NOAA calls in these graphics "departures": same thing.
6 - 14 Day Outlooks
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 available in Part II of this report.
To put the forecasts which NOAA tends to call Outlooks into perspective, I am going to show the three-month OND and single month of October forecasts and then discuss the 8 - 14 day Maps and the 6 - 14 Day NOAA Discussion within that framework.
Here is the Three-Month Temperature Outlook issued on September 17, 2015:
And here is the October only "Early" Temperature Outlook issued on September 17, 2015.
Below is the current 8 - 14 Day Temperature Outlook Map which will auto-update and thus be current when you view it. 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 below of the 8 to 14 day Outlook only shows seven days. The 6 - 10 Day Map is available on Page II of this report. As I view this map on September 28 (it updates each day) it appears that October will start out kind of the opposite of the monthly forecast in terms of the pattern of warm and cool anomalies north versus south. This suggests that El Nino has not yet begun to have significant impacts on CONUS weather.
Here is the three-month Precipitation Outlook which was issued on September 17, 2015:
And here is the October "Early" Precipitation Outlook Update Issued on September 17, 2015.
Below is the current 8 - 14 Day Precipitation Outlook Map which will auto-update and thus be current when you view it. 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 covers seven days of the nine. The 6 - 10 Day Map (the two maps overlap) is available on Page II of this report. As I view this map on September 28 (it updates each day) it appears that the Northern Tier is not yet in sync with the full month outlook.
Here are excerpts from the NOAA discussion released today September 28, 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.
One of the first things I noticed was that there was only one El Nino analog and there were two La Nina analogs. Also there were three neutrals that followed powerful El Ninos. What message is that delivering? The phases of the ocean cycles vary quite a bit but were most consistent with McCabe Condition B which is associated with a lot of wet but dry Plains States which is not unlike an El Nino pattern. The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. My take away from this is that the PDO has not changed phase and the current PDO plus is related to the current El Nino and the prior near El Nino. It most likely will return to PDO - or PDO neutral next winter.
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 significant. 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/rolling average.
The 30-day average, which is the most widely used measure, on September 21 was reported as being -15.9 which is clearly a reading associated with an El Nino and higher than last week. The 90-day average also is solidly in El Nino territory at -16.51 which is marginally less negative than last week and has converged with the 30 day average. The SOI is clearly indicative of an El Nino Event in progress. In fact it is so strong that it may be having impacts that are unusual.
Here are the low-level wind anomalies. It has been fairly calm although there is some new activity around 160E and it has turned out to be more significant than I originally thought it would be. But is not quite as intense as the earlier wind bursts. Could there be yet another Kelvin Wave?
In the below graphic, you can see how the convection pattern (really cloud tops has since May shifted to the East from a Date Line (180) Modoki pattern to a 170W to 120W Traditional/Canonical El Nino Pattern. But recently the signs of an El Nino are getting quite faint and shifting back to the west. You can see the lack of convection over at 120W which is Indonesia but the convection has withdrawn to the West not moved to the East as would be the case with a normal El Nino. That may still happen. In the 1997/1998 El Nino, that did not happen until 1998 which is why the Fall of 1997 was not wet for CONUS.
When I hear that with this El Nino the atmosphere is strongly coupled with the ocean, I really wonder what those meteorological agencies are smoking. It might be true on a worldwide basis but it does not appear to be the case as it impacts CONUS. The convection has not moved east. It has moved away from Indonesia which is an El Nino impact but it is remaining where one would expect it to be if this was a Modoki. This graphic may start to change soon. But it may not be in the direction of more convection further east. The September 20 Update which is what I am looking at on Monday September 28, suggests the area of convection has actually moved considerably to the west not the east.
Let us now take a look at the progress of the Kevin wave which is the key to the situation. Since February there have been three successive downwelling Kelvin Waves without really an upwelling Kelvin Wave of any consequence to counter their impact. The first wave which started in February was the most effective at getting this El Nino started. The second wave reinforced to some extent but not much and this third (and I believe last) downwelling Kelvin Wave has created an El Nino that will have a major peak coming soon and an extended life but at a diminished strength.
The main impact of this latest Kelvin Wave has already moved east to 140W. You also see the intense activity between just west of 120W and extending to just east of 100W. Kelvin waves move east so this most intense part of the Kelvin Wave has now moved east of the Nino 3.4 measurement area. Until recently we were able to see the cooling down of the water east of 90W but that has filled in recently as this latest and perhaps last Kelvin Wave moves east. The maturation of this El Nino is a slow process and every El Nino has a different length. But if you think of an El Nino as typically lasting about a year or less, then this one is about half through its life.
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. When I examine the current situation as compared to the 1997/1998 El Nino which I described graphically last week, the current El Nino has developed more rapidly. This El Nino is a couple of months further along in its evolution than the 1997/1998 El Nino and will end earlier in the winter than the 1997/1998 El Nino. Also the 1997/1998 had a larger amount of slightly warmer subsurface water in the Eastern Pacific and that water takes time to surface, create convection, and thus cool. Something happens to allow the Easterlies to resume their strength and that in turn moves this water back towards the Western Pacific Warm Pool. This El Nino appears to be fading from west to east.
Current Sub-Surface Conditions
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.
The top graphic is the most useful of the two and shows where 2C (anomaly) water is impacting the area in which the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to 160W which is very impressive. There is also a small blip over at 175W. The subsurface warm water is making its way to the surface in the Eastern Pacific especially in the vicinity of 110W but also to some extent working its way deeper. The 3C anomaly is over to west of 140W which again is very impressive and which encompasses more than 40% of the Nino 3.4 Measurement Area for the ONI. One can see how the ONI can continue to increase for some time due to this warm subsurface water that is coming to the surface or at least appears to the way the ONI anomalies are calculated.
One big issue is where will the +6C and +5C anomaly water go as it reaches the beaches of Ecuador? To the extent it prevents cooler water from reaching the surface, it can enhance 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 and there is some indication that some of it is working its way deeper where it probably will mix with cooler water coming north from further south. 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. But it is certainly taking its sweet time probably because of the large amount of the subsurface warm water. Water is a very good insulator: I believe it has the second highest specific heat capacity of all known substances.
It is important to differentiate between anomalies and actual temperature. The warm anomaly shown in the upper graphic is not covered by colder water as it might appear to be in the upper graphic but is shown as a warm anomaly because normally water at those depths is colder than it currently is. That is why this warm anomaly does not simply rise to the surface as warm water would normally do but it is preventing cooler water from entering the area as one would expect as summer transitions to Fall. That is why it takes time for this warm anomaly to dissipate.
So that means that other than by mixing, that warm water under the surface will stay warm until it rises to the surface where it can be cooled by evaporation (while making clouds) or moves to the north where it will impact Mexico and the Southern Coast of the U.S. That is part of the basis for models predicting that the ONI of this El Nino will continue to rise.
Bottom Graphic (Absolute Values which highlights the Thermocline)
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 yet fully making it to the surface to the east along the coast of Ecuador. However, one now can see the increase in the slope of the thermocline (look at the 25C dividing line for example which has now reached the surface). We can now begin to monitor the 20C Isotherm which is often thought of as being the middle of the thermocline where the slope is also steepening and looks like it may reach the surface fairly soon. I have been saying that for a while but there has been essentially no change. We may want to pay more attention to the 28C Isotherm as west of that temperature is where convection is more easy to occur. Right now that Isotherm intersects the surface near 130W which is not much change since last week and may actually be backing off a bit.
Taking a close look at the bottom half of the TAO/TRITON graphic, notice that things are continuing to heat up. But so far there are few if any impacts on CONUS. So this raises real questions about how we measure an El Nino and how we do regression analysis on historical El Ninos.
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 (that I have designated A through E (from west to east) with a location bar shown under the TAO/TRITON Graphic) 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 as of Monday September 28 in the afternoon working from the September 27 TAO/TRITON report, this is what I calculated which is bit higher than my calculation last week.
My estimate of the Nino 3.4 ONI has increased to 2.3 with again a gradient from west to east. NOAA has today again reported the weekly ONI as being 2.3 and that is certainly a very high level for an ONI even though it is a weekly value not a three-month average. The increase in the NOAA estimated ONI is I believe mostly due to the subsurface water in the Eastern Pacific maintaining the surface temperatures in the Nino 3.4 Measurement Area. The base changes seasonally and I do not have those numbers so it is a little hard for me to tell if the surface is actually warming or if what is happening is that the surface temperature is remaining constant and the base declines as winter approaches so a constant surface temperature records as an increased anomaly. In theory I could compare the graphics from week to week and perhaps figure that out. This warm water or at least warmer than normal for this time of year certainly impacts the weather in Ecuador and Peru but may not have a direct impact on weather in CONUS other than by spawning tropical cyclones which move north and enter the circulation of the Southwest Monsoon. It gets complicated because it seems that north of the Equator the water is definitely warmer and that is where tropical storms form.
Nino 4.0 is again reported as being 1.1. The action which I think is most important to track is in Nino 1+2 which is now reported as being up to 2.7. One issue remains the extent to which warm water off of Ecuador and Peru impacts CONUS weather. I think it has very little impact and that is what we are seeing right now. The other issue is that most El Ninos decay from east to west so it will be observed most clearly first in Nino 1+2 and we are not seeing that yet.
This is summarized in the following NOAA Table which has changed only slightly since last week with the Nino 3 and Nino 1+2 switching their readings which is probably not statistically significant. You can also see the trends in this table which other than Nino 1+2 seem to have peaked or are already in decline. I believe that watching Nino 1+2 is the best way to track when this El Nino will begin to seriously decay. Curiously some of the warm water appears to be going deeper which I think accelerates the decline but I am not sure of that. The subsurface warm water has to be disposed of one way or another for ENSO to move back towards neutral or all the way to La Nina.
One wonders about these calculations as they appear to not be related to the "adjusted" version of the NOAA forecast model which was discussed earlier.
Here is another way of looking at it: Unlike the Upper Ocean Heat Anomaly 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. As you can see the warm water rising off the South American Coast had (or at least the value of the anomaly when calculated) worked its way all the way over to beyond 170W so it fully contributes to the increasing ONI but is showing some signs of stalling. One can see the anomaly getting more intense at 110W to 100W. Until recently, we could see that the water immediately off the coast of South American was generally cooling down but that has reversed and that area is showing an increase in the SST anomalies. It is a dynamic process. There remains a lot of subsurface warm water to be disposed of. That is a slow process and will continue for some time. But there are some signs that the process is close to peaking. The projection is for the ONI to be a bit higher than where it stands at 2.3 so we will see if this makes it to 2.4 (for a three-month period) tying the 1997/1998 El Nino or sets a new record. The peak is likely to occur within the next two months but you need a three-month average for it to be an official peak. This suggests that to get an ONI of 2.5 there will need to be a period of time where the weekly ONI is higher than that.
When you break it down by the areas used to track ENSO you get values for each of the four Nino Regions and those values and their trend is shown in the graphic presented just prior to this Hovmoeller.
El Nino in the News
El Nino may impact Brazil. This is one of many articles on this topic. Brazil is a large nation with different climate zones and a complex pattern of where crops are grown. So the exact impacts by crop are difficult to predict.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
First the Temperature and Precipitation Departures from three months ago (Ending Date June 13)
Then the same graphic one month later (Ending Date July 11)
And then the same graphic (Ending Date August 8).
So this gives us a three-month sequence of monthly departures and that series of graphics showed a drying trend which is not exactly what you would expect with an El Nino arriving. For many parts of CONUS, it was a cooling trend also which may be associated with an El Nino.
And now the view from September 19 which is six weeks later.
And the view from September 26 which is almost two months later than the 8 August graphic and just a week later than the above graphic and remember it is a 30-day average so only 7 out of 30 days has changed. So that addition and subtraction of 7 days has changed things a bit.
We see a lot more warmer than climatology area across CONUS and some wetter areas in western Mexico due to the tropical storms. It is still mostly dry in CONUS.
View from Australia
Here is the discussion just released:
IOD (Indian Ocean Dipole)
It comes with only a very short discussion and here it is:
To me it is interesting that the IOD appears to have peaked and is on the way down. But the interrelationship between the IOD and El Nino is complicated and not fully understood.
Putting it all Together.
We are in El Nino conditions now. The actual impacts on CONUS are not clear. We started in the Spring by having wetter conditions than usual in the Southwest but that has tapered off quite a bit. It is probably influencing the IOD to tend towards being positive thus providing a double whammy for parts of Asia and Australia but this is projected above to continue for only a month or two. That by itself should make us wonder what exactly is going on.
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. There does not seem to be an obvious match to any prior El Nino in the modern era which to me means there is no model to use to predict 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 and may be moving back to PDO Negative. 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 as indeed the storm track for hurricanes in the Atlantic is suddenly unusually warm.
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.
We are beginning to speculate on the winter of 2016/2017 which I believe will tend to be ENSO Neutral but I am not so sure that it will not lean towards being a cool event or at least closer to a La Nina than 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 but perhaps for a shorter portion of the winter than NOAA has been predicting. JAMSTEC is predicting that the Spring of 2017 will begin a mild La Nina. That is a long way to make a prediction for a number of reasons including the Spring Prediction Barrier.
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
D,4. Reports from Around the World on Impacts of Global Warming.
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