posted on 20 July 2015
Written by Sig Silber
NOAA Issues a new Seasonal Outlook on July 16 which is essentially unchanged from the prior Outlook issued on June 18. Perhaps the passage of a month has increased their confidence in the forecast but there do not seem to be any significant changes. Next week I will discuss the differences between the NOAA Outlook and the view from Japan. But this week I focus on the report issued this past Thursday. The short-term Outlook is also of interest. There may soon be a break in the Southwest Monsoonal rains (which impacts many more states than just in the Southwest) but not all the models agree. For this winter, this El Nino may exhibit some start and go characteristics with two peaks of impacts due to the formation of yet another Kelvin Wave. This winter should be very interesting.
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 Seasonal Update.
Prior Aug - Sep - Oct Temperature Outlook
New Aug - Sep - Oct Temperature Outlook. It is fairly similar but the area of colder than climatology is now shown to further extend into the Great Lakes region.
Prior Aug - Sep - Oct Precipitation Outlook
New Aug - Sep - Oct Precipitation Outlook. It is also fairly similar to the prior assessment but also shows the extension of the wetter than climatology area to the east but south of the Great Lakes region.
The graphic below compares the new August Outlook to the updated three-month Outlook for Aug - Sep - Oct. The three-month Outlook which includes August is very similar to the August Outlook suggesting that September and October are themselves expected to be quite similar to August but with further extension of the wetter than climatology area to the East into the Midwest. There are also some small differences between the top maps which describe this August and the bottom maps which describe the three-month period including August with respect to South Texas, the Northern Great Lakes, and the upper Northeast. Those are fairly minor differences.
Now let us look at the full set of forecast maps which combined with the current month of August represents a 15-month Outlook.
Here is the prior 15-Month Temperature Outlook
And below is the newly issued 15-Month Temperature Outlook. It is a little difficult to compare this set of maps with the above previously issued set because the new set drops Aug-Sep-Oct 2015 and adds Aug-Sep-Oct 2016. This means that to compare the new maps in the below array with the previously issued maps in the above array you have to mentally shift the location of each of the maps in the below array to the right one notch and if it rolls off the page into the right-hand margin when you do that, you mentally move it down to the next row on the left. When you do that the maps for similar periods of time line up in the below graphic with the above graphic. If you print it out, it may be easier to do the comparison as you can circle a particular three-month period in the new version and the former version and compare them. I have done that and concluded that THERE IS ESSENTIAL NO SIGNIFICANT CHANGE IN THE OUTLOOK.even though NOAA issued a long discussion which we will cover later on in this report.
Now let us look at precipitation.
Prior 15 Month Precipitation Outlook issued on June 18
Now below the new 15-Month Precipitation Outlook issued on July 16. Again to compare a given three month period, you have to deal with the fact that the position of the three-month period changes when you are doing this a month later. I discussed under Temperature how I make the comparisons. And again for precipitation, THERE HAS ESSENTIALLY BEEN NO SIGNIFICANT CHANGE IN THE OUTLOOK. Some of the maps have been changed ever so slightly so these small changes may be important depending on where a person lives or is planning to visit etc but overall the Outlook is almost identical to the Outlook issued a month ago.
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.
The overall message that I get from looking at the new maps and the prior maps is that the forecast of a moderate to strong El Nino is determining the temperature outlook through May - Jun - Jul 2016 which means June of 2016 (June is the centroid of the three-month average) and the precipitation outlook through Mar - Apr - May 2016 which means Apr. After that point in time, the maps reflect climatology. For precipitation that means Equal Chances or EC everywhere and for temperature it means a mainly warmer than climatology projection as the climatology reflects a warming trend. This trend may be Global Warming, the PDO, or the AMO as NOAA does not specify the basis for the trend they refer to. "Climatology" is defined by NOAA as being the average conditions over the previous three completed decades. So if there is a trend in temperature, the odds are high that the projected temperatures will be shown as a positive anomaly.
Here are excepts from the discussion issued by NOAA as part of the Update of the Seasonal Outlook. They issue two discussion documents. One is focused on the next 30 days and the other is focused on the full 15 months. So I integrate the two documents, remove redundancy, remove the parts of the discussion that in my mind are less interesting, reorganize the sequence of presentation and in other ways attempt to make it more readable but I do not modify the content of the NOAA discussion other than where I insert Editor's Notes. You can read the originals of the discussion here and here.
Switching from the 15 Month Outlook to the Current (Now to 5 Days forward) Weather Situation:
A more complete version of this report with daily forecasts is available on Part II. This is a summary of that fuller 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 lick a second time within the TABLE OF CONTENTS to get to that specific part of the webpage.
First, here is a national 12 hour to 60 hour forecast of weather fronts shown as an animation. Beyond 60 hours, the maps are available at the link provided above.
The explanation for the coding used in these maps, i.e. the full legend, can be found here.
The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients. You can see the location of the Four Corners area where Utah, Colorado, Arizona, and New Mexico meet. At this time of the year there is typically a high pressure system near that area and it is called the Four Corners High. Small changes in the location of that feature make a big difference in the weather of probably about ten or more states. Note the Day 7 location of the Four Corners High was at the time I wrote this report projected to be somewhere other than over the Four-Corners area. It possibly explains the projected western shift in the impacts of the North American Monsoon (which probably is more properly called the Sonoran Monsoon). The Four-Corners High controls the circulation of moisture related to the North American Monsoon at least in terms of North of the Border with Mexico.
It certainly explains the warmer than climatology conditions in Texas. But this High moves around a lot so by the time you view it most likely it will be located somewhere else. But you can always 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.
In the Tropical Weather Outlook graphic below, notice the stream of moisture moving north from Mexico into the Southwest. To some extent this is enhanced by the position of the extreme western edge of the influence of the Bermuda High. Hurricane Dolores has finished having its impact but there is yet another cyclone following on its heels. After that storm there may be a temporary break in the action.
The below graphic is harder to look at but provides more detail on the vapor being generated by these storms and the normal summer action of the Southwest Monsoon.
Looking at a larger area, 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). The Aleutian Low may have finally agreed to take its usual summer vacation. The RRR has moved further off shore but is very strong and continues to block storms arriving on the Pacific Coast. Remember these maps update every six hours.
Outlook Days 6 - 14 (but only showing the 8 - 14 Day Maps)
Remember that the maps shown for the 8 - 14 day Outlook on Monday include three days of August and four days of July By the time most people read this report on Tuesday, the auto-updating will change the situation to be three days of July and four days of August. That is why at this time of the month I show both the full month outlooks for the current month and the subsequent month in this case July and August.
Here is a graphic of the July Temperature Outlook issued June 30, 2015.
And here is the "Early" Temperature Outlook for August that was released on July 16, 2015 and which is not very different from the July Outlook except for less extension into the Great Lakes Region.
And here is the current 8 - 14 Day Temperature Outlook 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 of the 8 to 14 day Outlook only shows seven days. As I view this map on July 20 (it updates each day), it suggests that August may turn out to be warmer for the Southwest than previously anticipated.
And here is the Outlook for July Precipitation issued on June 30, 2015:
And here is the Early Outlook for August Precipitation that was released on July 16, 2015 which like the temperature outlook, the precipitation outlook for August is less extended into the Midwest and Great Lakes Region.
Here is the current 8 - 14 Day Precipitation Outlook which will be auto-update daily and thus be current when you view it. And again remember that this map shows only seven days and the full 6 - 14 Day Outlook only covers nine days. There are 31 days in July. As I look at this map on July 20 (it updates automatically each day), it looks more like the JAMSTEC forecast but I am not planning to discuss that until next Monday.
Here are excerpts from the NOAA discussion released today July 20, 2015.
But I also have some very recent comments from the 'National Weather Service - Albuquerque Weather Forecast Office.
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.
The first thing I noticed is that today is July 20 and these are analogs centered on either July 16 or 17 (NOAA works with two different sets but I report them together). And by an large the analogs are aligned with the current calendar. This suggest that we are going to have typical weather for this time of the year. There were two outliers.
Last week It was interesting that for the first time we had all the analogs being El Nino or pre-El Nino in nature. This week it is a mixed bag which may be related to the possible break in the activity of the Southwest Monsoon. The 1972 El Nino analog is quite interesting as it was followed by two subsequent strong la Ninas and then the 1976 Climate Shift in the Pacific which ushered in a wetter period for the Southwest as the PDO changed from PDO - to PDO+ which lasted until possibly 1998 although some might think it lasted until 2003. The ocean phases associated with the analogs this week are quite mixed and to the extent they tell us anything, they point towards McCabe Condition B or D and since those are so very different they tell us nothing. The seminal work on the impact of the PDO and AMO on U.S. climate can be found here.
You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with each of the four pairs of two phases of the AMO and PDO.
Historical Anomaly Analysis
When I see the same dates showing up often I find it interesting to consult this list.
Progress of the Warm Event
Let us start with the SOI.
Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day moving/running average and the third is the 90 day moving/rolling average.
This past week has been favorable for the development of the current El Nino. The 30-day average, which is the most widely used measure, on July 20 was reported as being -19.38 which is clearly an El Nino reading. The 90-day average also is solidly in El Nino territory at -11.22. So the SOI averages have not changed very much partly because they are a moving/running average i.e. as each new day's data is added, the data for an earlier day either 30 or 90 days earlier is removed from the calculation. So you really have to take a look at the values for the days removed from the calculation to fully understand how the average is impacted. But the SOI is clearly indicative of an El Nino Event happening.
Here are the low-level wind anomalies. This graphic is not as compact as the graphic provided by the weekly NOAA ENSO Report (more white space) but this version auto-updates so you will always have the latest version of this Hovmoeller. As you can see, the wind gust of a several weeks ago at 160E is over. 160E is where the prior Kelvin Waves formed and if you look earlier in this Hovmoeller you can see that in Feb, Mar, and May. Will it happen again now? A subsequent but less intense wind gust occurred at 160W to 140W (which was probably along the path of the MJO transit) but it also appears to have just about played out. Is there enough warm water in the Western and Central Pacific to create a substantial Kelvin Wave? I do not think so. But there is a new Kelvin Wave. It's significance is yet to be determined.
Here is another graphic that is less compact than the prettied up version published by NOAA on Mondays but which has the advantage of auto-updating. You can see how the convection pattern (really cloud tops has 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 to the west. The probably impacts on CONUS are thus lessened. The impacts of an El Nino during the summer in the Northern Hemisphere are subtle.
Let us now take a look at the progress of the Kevin wave which is the key to the situation. I like this Hovmoeller a lot and I have now been able to find a version that autoupdates but is not prettied up. I will take the auto-update feature. You can see the Kelvin Wave that got started in February which started this Warm Event. There have been earlier such events that proved to be not very strong. But if you look at the bottom of the Hovmoeller which represents the current situation, you can see that this latest Kelvin Wave is moving to the East fairly rapidly and we will see the impact of that on declining ONI estimates fairly soon. The strongest impact is no longer shown on this graphic as it occurred a week or two ago. The main impact of this Kelvin Wave is already East of 170W the western-most extension of the Nino 3.4 region. In less than two months it has moved to the east 30 degrees of longitude to 150W so I think that within 2.5 months (i.e. Early October 2015), the ONI values will be way under 1.0 and very close to ENSO Neutral.
In their weekly ENSO EVOLUTION REPORT NOAA previously highlighted an upwelling phase of a Kelvin wave which might have signified the end of this El Nino event. Until now there has been no indication of a follow-up Kelvin wave being created but take a look over at 170E to the Date Line. This is yet another Kelvin Wave. There is some other information that I will discuss later in this report that suggests this Kelvin Wave is weak so far re the subsurface impacts but it has occurred and is likely to extend the life of this El Nino at least into late Winter and perhaps as projected by the models into early Spring 2016. We do not know yet the intensity of the El Nino beyond its peak in late Fall.
You can see below in the graphic which shows temperature along the Equator as a function of depth, both the magnitude of the anomalies and their size. You can now see where 2C (anomaly) water is impacting the area where the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to about 140W and the blips at the surface visible a few weeks ago further to the west are no longer evident. The subsurface warm water appears to be making its way to the surface to some extent in the Eastern Pacific. In the Central Pacific we now see a relatively small pod of warm water at about 175E where the westerly wind burst occurred and where we see above the beginning of one more Kelvin Wave. I believe we are seeing the same thing on all three graphics but different views of it and so far it seems to be fairly minor compared to what has occurred in prior months but that might change. It is however reaching the surface at about 160W and impacting the ONI calculations. We may get some additional insight when we discuss the TAO/TRITON graphic.
The big issue is where will the +6C and +5C anomaly water go as it reaches the beaches of Ecuador? To the extent it surfaces, it can create convection and impact the Walker Circulation which could then provide positive feedback to this El Nino. But that warm water might tend to go north or south or both. That is part of the phase out process for an El Nino and that is where we are in the life of this El Nino. It is peaking and will soon begin its decline. But it is certainly taking its sweet time probably because of the large amount of the subsurface warm water.
The bottom half of the graphic is not that useful in terms of tracking the progress of this Warm Event as it simply shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event and you can see that the cooler water is not making it to the surface to the east along the coast of Ecuador. However, one is beginning to see possibly a slight increase in the slope of the thermocline (look at the 25C dividing line for example) and the increase in that slope would be the final change as the El Nino dies. .
In the upper graphic, notice the boundary of the 1.5C plus water temperature anomaly (which is now the 1.0C plus water temperature anomaly) was last week close to 170W and moving towards the East. But it now has moved to the West somewhat. When I put all the information together I still conclude that I believe the ONI will soon peak and begin to decline. The possibility that there could be another Kelvin Wave forming is a piece of information that at this point is difficult to assess. And there is the issue of how the Walker Circulation might extend the life of this Warm Event. The question of the Walker Circulation is not separate from the question of the forming of another Kelvin Wave. Pretty much all of the issues I am discussing are interrelated.
Back to the TAO/TRITON graphic below, notice that the we now have two centers of warm water one to the east that is playing out as I had predicted and another minor reinforcement of warm water. The TAO/TRITON graphic updates daily and is presumably only day-old data so I put most of my faith in the below graphic. This phase of the El Nino is playing out. It exists. It is real unlike the Faux El Nino of 2014/2015. But it is maturing and playing out. It is also showing some signs of redeveloping as a follow on Modoki but that might turn out to be a follow-on traditional El Nino. To me, this being a summer El Nino, the near-term potential impacts on CONUS may currently be over-hyped since the real impacts will be felt this Fall and Winter. But on the other hand, there are signs that this may develop into a very powerful El Nno. So we have to watch what happens.
For my own amusement, I thought I would recalculate the ONI again as I have been doing recently. To refine my calculation, I have divided the 170W to 120W ONI measuring area into five subregions (that I have designated A through E 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 July 20 in the afternoon working from the July 19 TAO/TRITON report, this is what I calculated which is basically the same as my calculation last week although the patterns of the anomalies have been changing around quite a bit but the changes have been cancelling each other out.
My estimate of the Nino 3.4 ONI is now 1.68. NOAA has today reported the weekly ONI as being 1.7 a significant increase from that which was reported last week and essentially identical with my rough calculation.Curiously the increase in the ONI is mostly due to the subsurface water in the Eastern Pacific rising or reaching coastal areas and backing up to the west. This warm water 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.
Nino 4.0 is again reported as being 1.0 the level it was two weeks ago after having risen to 1.1 last week. You can already see (in my calculation table) the gradient from West to East that has formed with the higher values in the East and the Western part of the Zone having a smaller anomaly which I believe will soon decline slightly. But the new Kelvin Wave will arrive and then cause another rise in the ONI for the western part of the Nino 3.4 measurement area but so far that to me appears to me of smaller magnitude. This then may well result in a very complicated Walker Circulation pattern.
Here is another way of looking at it:
This Hovmoeller shows a lot of useful information. I could copy it into MSPaint and draw some lines on it but then it would not auto-updates so I do not wish to do that. But take a lot at 140E 160E, 165E, 180 (The International Date Line), 120W and 90W. Remember reading from top to bottom one is reading the earlier times to the more current times. So you can see how this Warm Event started at 140E, has moved to 160E and then to 165E and lately you can see continued movement towards 180, which it has now reached, but very slowly. You can especially see the impact east of 90W where the Kelvin Wave is crashing into Ecuador. Also more warmer water has expanded towards 120 W. The eastern progress of this Kelvin Wave has been slower than I had anticipated but now appears to be speeding up. The formation of the second part of the Kelvin Wave or a second Kelvin Wave if you prefer has extended the time during which the Kelvin Wave has been impacting the Equator. Leaving aside the SOI issue which until the past two weeks was no longer consistent with an El Nino, but has come to life perhaps just temporarily, this is clearly an El Nino type sea-surface temperature (SST) pattern right now. But to me it seems to be a pattern that will play out as it does not appear to be going to be reinforced.
You will not see the ONI decline until the warm water over at 180, The International Date Line, has moved to 170W. Until then, the ONI could easily continue to rise but probably not by very much although some models are predicting it will peak at about 2.0. Once the warm surface water no longer extends west of 170W, the ONI should begin to decline although apparently the seasonal pattern of sea surface temperatures along the Equator used to calculate the ONI declines into Fall (not sure why that is) and thus the reported ONI values might increase even as the sea surface temperatures (SST) decline. This of course in my mind suggests that there needs to be a seasonal adjustment made to the ONI.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
And the 30-Day which shows the more recent impacts
You can see the precipitation impact extending further to the east with perhaps a slightly less impact in the Southwest. The temperature departures have changed quite a bit in the center of CONUS with the Great Lakes becoming cooler and the Plains States warmer. It is always difficult to be sure you are attributing any of these changes to specific climate factors when they could be statistical artifact.
The View From Japan
JAMSTEC has updated their maps but due to the length of my report tonight I will not cover the new information from JAMSTEC. I will however compare the NOAA and JAMSTEC forecasts next Monday i.e. July 27.
The View from Australia
Here is the discussion that accompanied the model results.
Australia also has a proprietary model for forecasting the IOD which is basically the ratio of warm water to west in the Indian Ocean as compared to east over by Australia.
It comes with only a very short discussion which is:
To what extent are the ENSO and IOD related? That is discussed here.
And how does the IOD impact Australia? This is discussed here.
And there are variations of IOD. So if one wants to really delve into the subject you could read this article.
If you read more you will find that the relationship between the IOD and El Nino is complex and not really well understood. But for sure the IOD impacts weather in the Indian Ocean and adjacent land areas.
Pulling it All Together
We are in El Nino conditions now. It is probably influencing the IOD to tend towards being positive thus providing a double whammy for parts of Asia and Australia. The length and intensity of this El Nino is still not clear mostly in terms of whether or not it will extend into the early part of 2016. All the computer models predict that it will last longer than my mental model suggests to me. The disagreement is in terms of a couple of months but a couple of months makes a difference in terms of agriculture and other economic impacts. We may or may not have a Pacific Climate Shift as the PDO+ may be simply related to the Warm Event (and quite frankly at this point appears to be). But for now we do have PDO+. The AMO being an overturning may be more predictable so the Neutral status moving towards AMO- is probably fairly reliable but not necessarily proceeding in a straight line. So none of this is very difficult to figure out actually if you are looking at say a five-year forecast.The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I 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. But we are beginning to speculate on the winter of 2016/201 which I believe will tend to be ENSO Neutral. One thing is fairly certain for the U.S. it will be less wet and warmer than the winter of 2015/2016 which will be quite wet and cool. JAMSTEC is predicting that the Spring of 2017 will begin a La Nina but more on that next week.
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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