posted on 23 November 2015
Written by Sig Silber
A new seasonal outlook was issued by NOAA but it is not very different from the prior seasonal outlook. There are some minor changes and they are discussed in this week's report. Of interest, the transition out of El Nino conditions is now shown as reducing CONUS Southern Tier temperature cool anomalies in the February to May Period but does not impact the precipitation forecast until somewhat later in the April to June Period.
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 Issues Updated Seasonal Outlook. How has the Outlook Changed?
Let's start with the next three months looking at the Temperature Maps first.
Prior Dec-Jan- Feb 2016 Temperature Outlook
New Dec-Jan-Feb 2016 Temperature Outlook
Now let us look at the Precipitation Maps.
Prior Dec-Jan- Feb 2016 Precipitation Outlook
New Dec-Jan-Feb 2016 Precipitation Outlook
Here are Excerpts from the NOAA Discussion released on November 19, 2015
Lets Examine December and the Three-Month Period from a Different Perspective.
Combination Graphic showing the "Early" Outlook for December and the previously issued Three-Month temperature and precipitation Outlooks.
One can mentally subtract the December Outlook from the three-month Outlook and create the Outlook for the last two months in the three-month period namely January and February 2016. When I do that I deduce that January and February will be:
Now Let's Compare the Prior Outlook with the Updated Outlook for the Full Set of Maps.
Prior 14 Month Temperature Outlook Maps: Dec 2015 - Jan 2017
New 14 month Temperature Outlook Maps: Jan 2016 - Feb 2017
To compare maps from one release to another one needs to remember that the new release drops one three-month period and adds a later one. So to make the comparisons one has to shift the new maps to the right one position and that makes the map on the right drop down to become the left-most map in the next level. I do not have a computer software tool for doing that for you so you have to do it mentally. When I do the comparison I print them out and put them side by side and number the same three-month maps 1, 2, 3,.....,11 in both sets of maps to make it easier for me to easily compare the same three-month period in the new with the previous forecast. One uses the same procedure to compare the precipitation maps. Based on this procedure, I conclude that:
Now let us Look at the Precipitation Maps
Prior 14 month Precipitation Outlook Maps: Dec 2015 - Jan 2017
New 14 Month Precipitation Outlook Maps: Jan 2016 - Feb 2017
If you want larger versions of each map (temperature and precipitation) you can find them here. And each of those maps can be clicked on to further enlarge them.
Not Let us 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. 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. That is quite an impressive trough shown on this graphic. Forecasters have been having a hard time with this feature and in fact it changed dramatically from what it looked like Sunday afternoon to what it looked like Sunday evening and now today on Monday where it has changed during the time I have been doing the final edition of my weather column. It is definitely the major feature shown.
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 at Haby Hints for anyone who wants an explanation of a meteorological term. The thickness lines do not yet indicate winter conditions which might be thickness levels below 540 for most areas. This suggests that for the next two weeks, snow is not likely to be prevalent in CONUS other than in areas of high elevation and in the area impacted by the trough. The above uk.sci.weather link is is an explanation for the U.K. The levels for CONUS might be slightly different. Obviously these thickness lines do not tell you about mountain peaks. The particular definition of "thickness" on this graphic may not be the best way to define the snow line and this is discussed in the link provided but it is I believe the older method and gives a first approximation which can be further refined as per the discussion in the link.
The following table is useful but designed for Europe. I was not able to find the corresponding information for the U.S. but it would not be drastically different. In the U.S., the last zero is dropped off the Thickness Level so where it says 5640 that would show as 564 in the U.S. Also remember the temperatures shown are in Centigrade. So 580 would correspond to about 80F in full sunshine during the summer. That is why I say the 582 and 576 thickness levels still showing up in the Eastern half of CONUS are a bit unusual for early December. On the other hand the 540 thickness line is now in this Day 7 Forecast intruding into or close to intruding into parts of CONUS indicating that Winter has arrived in those areas. Although this is an imprecise tool, it is useful for a first look at the situation. One can refine the tool by looking at the temperature distribution of the air column to take into account warm and cool bias the relative humidity of the air (evaporative cooling potential) and of course the altitude as higher thickness levels will produce snow at higher elevation locations.
More information on this table is available here.
The level of storm activity in the Western Pacific has declined right now with the MJO it its inactive phase. 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.
Looking at the graphic below, the cyclones generated by the warm ocean water west of Central America can provide Monsoon-like impacts 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. 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 was the case this summer and continues in the Fall but it is sporadic. Hurricane Rick had no impact but now there is a new storm coming into the picture. If it develops, it will be Tropical Storm Sandra.
The graphic below is harder to look at but provides more detail on the water vapor in place which is a good proxy for where precipitation can occur. 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 the storm which is entering CONUS and predicted to travel down the Great Basin towards the Southwest and I see the generally dry conditions which are currently in place along the Southern Tier of CONUS. But I also see the impact of Tropical Depression Twenty-Two-E which may be labeled as Tropical Storm Sandra by the time you view this graphic This graphic updates automatically so it most likely will look different by the time you look at it.
Below is an analysis of projected tropical hazards and benefits over an approximately two-week period. There are two views.
The first graphic (A) is focused on the Eastern Tropical Pacific including North and South America. It updates on Friday so on Monday when I write my report, I pay most attention to this graphic for information on the tropical area of North and South America but it is mostly the week-two part of the forecast that is still relevant by the Monday following the Friday update.
The second graphic (B) covers the same area as the first graphic but it also covers the Western Pacific and the Indian Ocean. Since it updates on Tuesday, the first graphic (A) is more current on Monday evening for the Eastern Pacific including the tropical part of North and Central America which includes the U.S. Southeast. But by Tuesday, Graphic (B) is the preferred choice for the entire area of interest.
When looking at a lot of graphics, the dates for which the graphic applies and the dates when issued and updated become very important in making sense out of the information. It is easy to draw incorrect conclusions by not considering or getting confused by the different timeframes. The below discussion is based on the two graphics as shown on Monday but they continue to auto-update during the week and may look different than what I am seeing by the time you view them. More information on these two graphics can be found here.
Graphic "A" (which updates on Friday and from which I use the Week 2 of the forecast to look at North and South America). What is it telling us this Monday evening?
Mostly it is showing potential cyclonic development off the west coast of Central America coming to a halt after Hurricane Rick which turned out to not have an impact on CONUS. It also shows an area of above average precipitation continuing in the West Indies.
Graphic B (which updates on Tuesday and on a Monday I use the Week 2 of this Forecast to look at the Western Pacific and Indian Ocean). What is it telling us this Monday evening?
Mostly I see a fairly benign situation in the Western Pacific and Indian Ocean with moderate dryness in Indonesia and perhaps Monsoonal activity in Eastern India.
Below is a view which highlights the surface Highs and the Lows re air pressure on Day 3. I usually only show the 6 day graphic on Page I of my report (they both are always on Page II of my report) but because of the volatility of the situation in the Pacific this time of the year, I am again showing both this week. Notice the location and extreme intensity of the Aleutian Low forecast for Day 3.
Here is the Day 6 forecast In recent weeks the projected location and strength of the Aleutian Low has varied a bit. On some days, the forecast is showing a split low with each of the two lows weaker than a combined single Low and this is not characteristic of El Nino. Right now the Aleutian Low is projected on Day 6 to not be in the most ideal location for El Nino but it has an extension to the south which changes its impact to some extent. Its hPa of 976 is quite intense (the average in the winter is 1001hPa and 994 hPa for a non-split Low). The shifting position of the Low makes a big difference. As shown, the Day 6 forecast no longer calls for the RRR to valiantly "protect" the West Coast from Pacific storms. A longer discussion of the climate of Beringia and the role of the Aleutian Low is in Part II of this Report 2. Medium Frequency Cycles such as ENSO and IOD.
Looking at the current activity of the Jet Stream one can certainly see the current trough and also the southern branch of the Jet Stream.
And the forecast out five days. Of course this is a forecast and changes daily or perhaps even more frequently. The pattern has become increasingly meridional with the Jet Stream forming troughs and ridges as it moves across CONUS but with a split stream.
To see how the pattern is projected to evolve, please click here. The activity is projected to become quite meridional which allows troughs to bring precipitation down to lower latitudes. 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.
And when we look at Sea Surface anomalies we see a lot of them not just along the Equator related to El Nino. One sees a slight fading of the warm anomaly off of Ecuador especially north of the Equator and perhaps a reduction in size of the warm anomaly around Baja California which sometimes is referred to as the "BLOB". It is an unusual occurrence which the Japanese have referred to as the California Nino.
The two graphics below show first the changes over the four weeks (ending November 4) as compared to the above graphic which shows the current SST anomalies and then the changes over the four weeks ending on November 18, 2015. Looking at both of these change in anomaly graphics is helpful in putting the current situation shown above into perspective.
First the four weeks ending on November 4, 2015
I am also showing the new version issued today which adds two new weeks and removes the most distant two weeks from the average change in the Sea Surface Temperature anomalies.
These graphics are hard to interpret because they are four-week changes. But you have the daily values three graphics up. Here you actual see some strengthening in the El Nino to the west but continued reduction of the warm anomaly just off of Ecuador and extending down the west coast of South America. More importantly you see the extreme cooling of the warm anomaly off of the West Coast of the U.S. (reducing the degree of PDO+) and also Australia (reducing or eliminating the Positive IOD) and West Africa. The Gulf of Mexico however is warmer or less cool depending on how you want to look at it. So there are some significant changes taking place.
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 DJF and the "early" single month of December forecasts and then discuss the 8 - 14 day Maps and the 6 - 14 Day NOAA Discussion within that framework. Some of these graphics are repeats of graphics that I presented earlier as part of the discussion of the NOAA Update.
Here is the Three-Month Temperature Outlook issued on November 19, 2015:
Here is the December "Early" (it will be updated at the end of the month on November 30) Temperature Outlook issued on November 19, 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 November 23 (it updates each day), it appears that December may start out colder than the full month Outlook for parts of the West and Southwest.
Here is the three-month Precipitation Outlook issued on November 19, 2015:
And here is the month of December "Early" (it will be updated at the end of the month on November 30) Precipitation Outlook issued on November 19, 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 November 23 (it updates each day) it appears that December may start out less wet than the full month Outlook.
Here are excerpts from the NOAA discussion released today November 23, 2015. It covers the full nine day period not just the seven days shown in the 8-14 Day Map.
Since an "Omega Block" has been mentioned at least it was a few days ago, I thought it would be useful to explain it a bit.
More information be found at this Haby Hint. In our case to the extent this pattern existed, it was shifted to the west far more than the example shown. The Omega and Rex block patterns may be showing up more frequently this time of the year.
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 thing that jumped out at me right away was the less tight spread among the analogs from November 4 to December 6 which is almost five weeks which is less tight than recently and suggestive of more difficulty in pinning down where we are in the seasonal transition. There are this time only two El Nino Analogs (all Modoki Type II) and zero La Nina Analogs and five ENSO Neutral Analogs so again, this does not suggest that El Nino (even of a Modokish nature) is a major factor in our weather over the next 6 - 14 Days. The phases of the ocean cycles are fairly incoherent with a slight bias towards McCabe Condition D which has been the prevailing condition since 1998 and is associated with Southwest drought. Both the Atlantic and the Pacific are influencing our weather about equally. 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 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/running average.
The 30-day average, which is the most widely used measure, on November 23 is reported at -5.83 which is no longer a clear-cut reading associated with an El Nino (usually required to be more negative than -8.0 but some consider -6.0 value good enough) and very significantly less negative (El Nino-ish) than last week. The 90-day average also is rapidly declining but still in El Nino territory at -14.37 which is also quite less El Nino-ish than last week given that it is a 90-day average. The SOI no longer remains indicative of an El Nino Event in progress. This past week there have been not only no extreme values but all the values have been ENSO Neutral or La Nina values. This can be important as some studies show that the change in the level of SOI is at least as important as the actual level in terms of predicting precipitation.
Low-Level Wind Anomalies
Here are the low-level wind anomalies. In October, the area from 180W to 160W was of interest and quite intense. There then was an area of interest at 160W which also was quite intense. Now, calm appears to prevail.
In the below graphic, you can see how the convection pattern (really cloud tops) no longer shows the pronounced pattern that has existed for a number of months. This is especially evident to the west of the Date Line.
Let us now take a look at the progress of Kelvin Waves which are the key to the situation. Since February there have been three successive "genuine" 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 had believed would be the 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. We now see a fourth Kelvin wave which now appears to be stronger than I first thought and it now shows up in the TAO/TRITON graphic which is discussed later in this report. But we also now see less extreme anomalies at 80W and more importantly from 155W eastward. The most extreme temperature anomaly colored gray in the graphic, is beginning to slowly cover a smaller part of the Equator but has shifted to the east and is now located at 140W to 110W which means a smaller portion is in the ONI/Nino 3.4 Measurement Area namely the part that is between 140W and 120W. We also see a slight but accelerating retreat to the east of the western extreme of this pattern and an expansion to the east of the cold anomaly which is undercutting the warm anomaly. NOAA has now recognized this as the upwelling phase of Kelvin Wave #4.
I do not usually show the weekly ENSO report version of this graphic even though it is more attractive because it does not auto-update. I am showing it this week because the upwelling phase of Kelvin Wave #4 is shown: the dotted line off to the left in the blue shaded area. If there is no additional downwelling wave this kind of established the schedule for the demise of this El Nino.
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 recently, 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 slightly larger amount of warm 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 slowly from west to east. The real decline will be from east to west so that may be starting but has not progressed to any large extent as yet but there are signs that it is beginning.
Current Sub-Surface Conditions
One question on my mind with respect to this graphic relates to the operational problems with TAO/TRITON. I do not know the source of the data for this graphic and it has been changing very slowly so that has me wondering. I know for a fact that the TAO/TRITON System is not fully functional at this point in time. So there are gaps in the data that is being presented.
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 still 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 180W which is very impressive but I think it is drifting to the east . The 3C anomaly now extends to 160W so I am viewing the 3C anomaly as now encompassing almost 80% of the Nino 3.4 Measurement Area for the ONI. It explains how NOAA is coming up with such high ONI estimates. The 4C anomaly is again close to intersecting the surface and may be doing so in places but less so than last week. The Hovmoeller graphic that I show later suggests that this process may be more intense that shown in the above graphic.
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.
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. It shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event. You can see that the cooler water is not yet fully making it to the surface to the east along the coast of Ecuador. We now will 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 has been the case for some time but it appears to have moved a bit to the east which is consistent with the El Nino still intensifying.
Before starting this discussion I need to mention that I had for a number of weeks observed what seemed to me to be oddities in the data reported by the TAO/TRITON system which I have discussed in recent editions of my weekly report. I see no need to repeat the issue other than to remind everyone that the TAO/TRITON system may not be fully operational at this time. Never-the-less, I believe there is value in the analysis that I do using the TAO/TRITON information so I will for the time being continue to do that analysis but please keep in mind that the reliability of the data is in question right now.
Taking a close look at the TAO/TRITON graphic but first let us compare the situation as reported on October 4
to the most recent graphic shown below. 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.
With the current graphic, there is again a lot of resemblance to the situation on October 4. I now clearly see the new Kelvin Wave (#4) over at 170W (why is it not moving to the east?). The 2C anomaly on Oct 4 was showing all the way over to 170W. Now it extends even further to the west. But to the east of the current location of Kelvin Wave #4, the warm anomaly is lower until you reach 145W. This graphic changes quite a bit from day to day so my commentary can be out of date as quickly as tomorrow. The 3C anomaly extends only slightly beyond 120W perhaps to 130W and thus is only partially in the ONI/Nino 3.4 Measurement Area. We can now see a 3.5C Isotherm which is only impacting the ONI/Nino 3.4 measurement marginally. The Easterlies are diminished but now show as Easterlies almost everywhere (top graphic) which is different than recently when the anomalies were so strong that west of 150W they showed as having been converted into Westerlies. That could be an indication that the conditions for maintaining this El Nino are slowly changing.
It may be artifact related to less than full operation of the TAO/TRITON System but the graphic shows a definite decline in the warm anomaly north of the Equator in the western part of the ONI/Nino 3.4 Measurement Area. Remember the definition of the ONI Measurement Area is 170W to 120W extending north and south of the Equator by 5 degrees latitude. So we see in this graphic a lot of 0.5C to 1.0C water which is still of El Nino strength but just barely. We did not see that on October 4. If one had confidence in the TAO/TRITON system, one might talk about a break in the action as Kevin Wave #3 hits the Coast of Equator (or perhaps the Galapagos Islands) and then moves back closer to the surface to create a stronger warm anomaly in the Nino 3.4 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 November 23 in the afternoon working from the November 22 TAO/TRITON report, this is what I calculated.
My estimate of the Nino 3.4 ONI after rounding has increased to 2.3. NOAA has today reported the weekly ONI as being 3.1 WOW! I have already discussed the issues with the TAO/TRITON graphic which could cause me to underestimate the ONI.
Nino 4.0 is now reported as being 1.8, just a bit higher than last week, which probably reflects the passage of the new and fourth Kelvin Wave. The action which I think is most important to track right now is in Nino 1+2 which is now reported as being 2.1 which is slightly higher than last week. One issue remains the extent to which warm water off of Ecuador and Peru impacts CONUS weather. I think it has very little impact except from the tropical storms that move up the west coast of Central America and sometimes contribute moisture to the circulation over CONUS. Most El Ninos decay from east to west so it will be observed most clearly first in Nino 1+2 and we are now probably seeing that process starting but very slowly.
This is summarized in the following NOAA Tables and I am showing both the table for five weeks ago and the updated table.
And here are the values this week.
One can in the bottom chart on the right see the significant decline in the Nino 1+2 measurement area. This is confirmed in a graphic that I present later. I think it is quite possible that this El Nino has now peaked and has begun its decline. But NOAA is still reporting increases in the ONI value.
One wonders about these calculations as they appear to not be related to the "adjusted" version of the NOAA forecast model which was discussed recently. So it is not clear to me how this El Nino will be officially recorded. August-September-October has been recorded as having an ONI of 1.7. In the above graphic eyeballing it you might conclude that the three months were observed as being 2.0, 2.3 and 2.4. So the impact of adjusting these observed values to what is considered "adjusted" is not obvious to me. If 2.0, 2.3, and 2.4 when averaged and adjusted come to 1.7 how should we interpret the unadjusted weekly value of 3.1? To me it is meaningless but I dutifully report it.
Although I discussed the Kelvin Waves earlier, now seems to be the best place to show the evolution of the subsurface temperatures.
I do not see much change week to week and it is hard to know if that is reality or the issues with TAO/TRITON. I am not sure of the source of the data for this graphic. A couple of things are interesting however. The cool anomaly in the west under the warm anomaly is slowly creeping east undercutting the warm anomaly and now is now east of 160W (which I incorrectly reported last week as 180W which was a typo). In the east at around 100W it still looks like the warm anomaly is gradually splitting into two pieces but the graphic is not as dramatic.
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. 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. One can easily see the historical evolution of this El Nino and also the current "hot spots" that are showing up and leading to the very high ONI readings and also right now some withdrawal of warm water from off the Coast of Ecuador. But Kelvin Wave #4 may change that.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
First the Temperature and Precipitation Departures from five 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).
And now the view from September 5 which is one month later.
And again four weeks later (Ending Date October 3, 2015)
And again four weeks later (Ending Date October 31, 2015)
This provides a six-month sequence of snapshots of the four-week departures from normal as this El Nino has progressed.
You can see these graphics as well as I can and it is difficult to describe the changes that have taken place over six periods of time because of the large number of changes. Currently we see:
And one more:
Strangely it looks generally warmer and bit wetter but the warmer is fairly unusual for El Nino especially in the Southwest. But this is a 30 day average. I have not shown the graphic from last week but the warm areas are a bit less intense than last week and that should change a lot by next week. The wet areas are a typical El Nino pattern but that might change by next week if the Jet Stream remains mostly to the north.
And one more. And here you see some major changes which is a bit of a surprise given that the difference between the below graphic and one above is just seven days out of thirty.
I realize this is a lot of graphics but one needs to look at the history of an event to assess it and this 30 average really shows the shift in the temperature pattern and precipitation pattern.
View from Japan
This is the updated precipitation outlook.
Here is the new ONI forecast from JAMSTEC
Here is the discussion
But then there was this bonus discussion which is well worth reading. They do some bragging about the forecast model but it may be well deserved.
View from Australia
I do not see much change from the graphic released two weeks ago. Here is the discussion just released:
IOD (Indian Ocean Dipole)
I see a change from the graphic released two weeks ago in that the IOD index no longer looks to be pushing up against the limit later this year. The graphic comes with only a very short discussion and here is that discussion most if not all of which was covered under the El Nino discussion. .
The interrelationship between the IOD and El Nino is complicated and not fully understood.
El Nino in the News
This is a pretty good article on this El Nino. Of particular interest is this quote from the article.
I have been discussing these and similar issues in my weather column including also the position of the Aleutian Low and the persistence of the RRR off of California.
Here is another good article.
Putting it all Together.
The El Nino I believe has peaked in intensity and plateaued but NOAA continues to report ever increasing values for the ONI. 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 although that is starting to change. The El Nino has probably been influencing the IOD to tend towards being positive thus providing a double whammy for parts of Asia and Australia. Indonesia and the Philippines have been hit by drought. It seems though that the positive IOD has run its course and the drought in the Western Pacific is moderating.
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. That is a complicated subject which is probably best dealt with on a post mortem basis.
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 it now seems increasingly likely will be a La Nina. One thing that is fairly certain for the U.S.is that compared to this winter the following winter is projected to be:
The below is the recently issued CPC/IRI forecast and you can see the rapid shift away from El Nino that is now predicted starting in AMJ and really showing up in MJJ 2016 i.e. late Spring early Summer 2016.
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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