Written by Sig Silber
This week I focused on comparing NOAA’s recent Seasonal Update with the similar monthly update provided by Japan’s somewhat comparable Agency JAMSTEC to see what we can learn. In terms of the near-term situation for CONUS, it looks like the Southwest Monsoon is ending its downturn in activity – we pretty much can expect normal summer weather for a couple of weeks. This current weather is essentially non-related to the El Nino that is moving east and will impact Fall and early Winter in the Northern Hemisphere – and then slowly fade away (with some uncertainty as to how slowly that will happen). There is also right now a somewhat unusual incursion of cooler air from Canada via the Great Lakes which has an impact over a large area.
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.
View from Japan as Compared to the View from NOAA.
It is important to remember that both agencies have a different reporting cycle. Jamstec runs its ENSO model on the first day of the month and then everything else depends on that model run. NOAA issues their seasonal update on the third Thursday of each month so their initial conditions are a small number of days pror to that Thursday. So two reports for the same future time period which are presumably the most recent reports issued are not necessarily based on the same identical initial conditions but they should be quite close. The purpose of doing this type of comparison is the identification of differences. Such differences suggest what we need to monitor as weather patterns, in this case an El Nino and possibly an IOD, develop and eventually fade away.
Latest JAMSTEC ENSO Index Forecast
July 21, 2015
Prediction from 1st July, 2015
ENSO forecast: The SINTEX-F model predicts that the currently evolving El Niño reaches its peak in late boreal summer and maintains its amplitude until boreal winter. Based on the model predictions and the present observations of the tropical Pacific condition, it appears that this could be one of the strongest El Niño in recent decades.
Indian Ocean forecast: As predicted, the positive Indian Ocean Dipole (IOD) has come on the scene in this month. The positive IOD will continue evolving and reach its peak in boreal fall.
Regional forecast: In boreal fall, as a seasonally averaged view, most parts of Europe, Africa, Western Russia, India, Southeast Asia, Northern South America, Mexico, Canada, and East Asia will experience a warmer-than-normal condition. On the other hand, central/eastern U.S., southeastern Russia, and Southern South America will experience a colder-than-normal condition. Based on monthly pictures (not shown), Japan will be in a cooler-than-normal condition in August, whereas in September and October, it will experience a warmer-than-normal condition. The former may be related to immature Bonin high due to El Niño, whereas the latter may be related to the development of the positive IOD.
According to the seasonally averaged rainfall prediction in boreal fall, Japan, Indonesia, northern India, Australia (particularly northern Australia), and northern Brazil will experience a drier-than-normal condition. On the other hand, most parts of the Bay of Bengal, Baja California, and southern Brazil will experience a wetter-than-normal condition. All those may be partly related to El Niño and the positive IOD, together with their remote influences.
Note the forecasted peak ONI of about 2.5 (very high) and the decline starting right before New Year’s Eve. This is important because some studies may be showing that the impacts are not just related to the magnitude of the ONI but also to the rate of change of the ONI. The Queensland precipitation forecast model is based on the recent level and the direction of the change of the SOI Index and you can read more about that here. They are doing additional research on how to improve local forecasts and you can read more about that here. There are also lags and perhaps leads as the ENSO changes to the Atmosphere teleconnect to other parts of the World.
Latest NOAA ENSO Index Forecast
So these are quite similar but JAMSTEC is showing a faster rise and decline as compared to NOAA. But both show the ONI peaking in late 2015 with the levels then starting to decline prior to New Year’s Eve.
The above is the forecast for a single area of the Pacific what is called Nino 3.4 which appears to be the consensus to some extent as to where to measure the condition of the ENSO cycle. Now let us look at Sea Surface Temperature anomalies everywhere in the World.
First with JAMSTEC Sea Surface Temperature Anomaly June – July – August 2015
This forecast was not updated with the July 1 new model run of the ENSO Index probably because we are already halfway through July. This map was the first time JAMSTEC was showing a pattern that looked like a traditional El Nino Pattern with the warm water along the Equator extending all the way over to Ecuador and Peru.
There is a NOAA version for ASO which is not covering identical months as it is ASO versus JJA but it is still of interest.
Some of the differences are the way the graphic artists display things (overkill) but it does seem that the NOAA forecast of SST is more intense. Of special interest is the greater extent of the warm anomaly in the Eastern Pacific north of the Equator. That can make a difference in the weather forecasts.
Now let us look at the key months which are the Fall of this year. First JAMSTEC
Sea Surface Anomaly Forecast Sept – Oct – Nov 2015
Some significant changes are shown here with a more clearly define PDO Positive. See the cool anomaly in the Central Pacific between 40N and 50N above the Date Line. The Atlantic and the Gulf of Mexico at this point are still shown as relatively warm.
And here is the NOAA version for the same months SON 2015.
Again NOAA is showing a warmer Eastern Pacific in the Northern Hemisphere. They are also showing a less warm Gulf of Mexico and less warm area in the Atlantic but a very intense warm area east of Florida.
Now let us look further out into the heart of winter. First JAMSTEC
Sea Surface Anomaly Forecast Dec 2015, Jan – Feb 2016
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. But the AMO is more Negative.
And the NOAA version.
Looking out west and north of Australia, I have not decided what to think about the IOD and if the JAMSTEC and NOAA maps are saying something significantly different about the IOD. The treatment of the Indian Ocean in the NOAA map seems to be consistent with their view on El Nino.
Now looking quite far out to March to May. First JAMSTEC
And you can see the warm water having moved to the west and at this point the location of the warm water is more like a Modoki perhaps even the beginning of a La Nina. Note the Atlantic which continues to be in AMO- mode but even more so than the forecast for DJF.
The most distant in time NOAA map is JFM 2016 so it is not exactly comparable with the MAM map above but that is what I could find so here it is.
In the prior map, JAMSTEC is showing El Nino turning neutral or into a Modoki but NOAA in this map is still showing a Traditional El Nino going into 2016. That is an important difference. The precision of the NOAA maps may actually conflict with interpretation as can a model actually predict the shape of the warm anomaly with the precision shown in the above map? And how can JAMSTEC and NOAA differ that much on the condition of the Atlantic Ocean? That is very important
The sea surface temperature anomalies (SST’s) are then used to forecast temperature and precipitation. So let’s look at those maps.
June – July – August 2015 Starting with JAMSTEC
The forecast was not updated when JAMSTEC issued their July 1 updated ENSO forecast presumably because we are already in the middle of July. This map shows a cool summer for the U.S. but warm essentially everywhere else except part of Siberia.
Here is the NOAA outlook issued on May 21, 2015
The forecast was very different from the JAMSTEC forecast and showed a pattern of warm – cool – warm going from west to east. I do not think either map nailed it but we are still at the end of July so one can not draw definitive conclusions on that until we know what happened in August.
Okay let’s take a look at the temperature forecasts for the Fall. First JAMSTEC.
There is a clear pattern here of a warm west in CONUS and a cool east.
And here is the NOAA Version
It is a stretch to conclude that this map is similar to the JAMSTEC map. The warm west however is common to both forecast maps. But the NOAA map unlike the JAMSTEC map predicts less cool and even warm in parts of the East Coast.
Now let us take a look at the winter Dec 2015, Jan – Feb 2016 and again first JAMSTEC
Not everywhere but still basically cold in the southeast U.S. and also Europe. A negative NAO perhaps. Again I am guessing perhaps the Aleutian Low will be weakening as the El Nino fades away but southern Alaska is still shown as warmer than climatology which suggests the Aleutian Low will be strong. The rest of CONUS is not shown as being warmer than climatology and I think that is a change from the prior model run.
And the NOAA Temperature Version for those same months
NOAA seems to be on the cool side which I interpret as being a bit more enthusiastic about El Nino impacts on precipitation which we will look at shortly.
And now the March to May 2016. Again first JAMSTEC
Again it is back to a warm Alaska and the west and a cool eastern CONUS. But parts of Europe remain cool as well as Iran, Afghanistan, and Argentina.
And the NOAA Temperature Outlook for the same three months.
There is some similarity but I think overall NOAA is less warm. The coding system might be complicating the ability to look at these graphics and compare them as NOAA uses EC when they are not sure and JAMSTEC shows lightly shaded areas.
Now let us look at the precipitation. Starting with JAMSTEC
June – July – August 2015
This forecast has not been updated when JAMSTEC issued their July 1 ENSO Index Update presumably because we are already in the middle of July. When issued in June, this forecast called for wet in the U.S. and dry in India and Australia. Japan looks wet on this map, Central America dry. The geography between perhaps 90E and the Date Line is very interesting with a wet band further north of a dry band. Exactly where these bands end up could impact Indonesia and other places.
And here is the May 18, 2015 NOAA Precipitation Outlook for those three months.
It was less aggressive with respect to predicting wetter than climatology. It is too soon to say which forecast was more on target but June was very wet in the west and southwest but July less so.
Now let us look at Precipitation in the Fall Sept – Oct – Nov 2015 again starting with the JAMSTEC map.
JAMSTEC is still showing wet in the U.S. and dry in India and part of Australia. Equatorial Africa is wet. Eastern South America is dry (El Nino). It looks like Indonesia is dry.
And here is the NOAA Outlook for these three months .
The NOAA forecast and JAMSTEC forecast are pretty similar for that period with regards to CONUS..
Now let’s look at the heart of winter Dec 2015, Jan – Feb 2016 and again starting with JAMSTEC.
Looks like the impacts of the El Nino begin to fade away slightly in this time period or at least for CONUS shift to the west. But Southern Europe is wet corresponding to them being cold. India returns to normal. Australia is dry.
And the NOAA Outlook for the same three Months
There is a lot more of a north south divide in the NOAA forecast. NOAA is less confident than JAMSTEC that Alaska will be drier than climatology.
Final we take a look at next Spring. And the March April May 2016 Precipitation Forecast and again starting with JAMSTEC.
And the NOAA precipitation outlook for the same three months.
I can not explain why the JAMSTEC forecast is so much wetter for these months than the NOAA outlook especially since NOAA thinks El Nino will last longer than does JAMSTEC but that is what the maps are showing.
The differences between JAMSTEC and NOAA are not enormous but they are substantial enough to wonder why the two agencies see things a bit differently. I hope this comparison which is tedious for the reader to read and whch was very tedious for me to prepare was useful. Feedback would be appreciated. Warning: A lot of these graphics will auto-update over time. I could have frozen them and may go back and do that so that we can look back in six months or so and compare the forecasts to the actual, but as it stands this comparison is good for a few weeks but in a month will not look the same as it does now as the graphics auto-update unless I go back in and freeze the images which is a lot of work.
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 is now projected to be a bit to the southeast of the Four Corners which is a very favorable location for the circulation to bring in warm moist air from Mexico. 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. But this High moves around a lot so by the time you view this report, 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 that there is no Pacific Tropical Storm projected to be close enough to the coast to impact CONUS. That is why last Monday I raised the question as to a possible temporary break in the action. That is common in the Summer for CONUS. The Sonoran Monsoon which we commandeered and renamed the North American Monsoon or the Southwest Monsoon is a serious of bursts and pauses in activity as it impacts the ten or so states in CONUS with the major impacts being with respect to New Mexico and Arizona. That break in the action occured and may soon end with the Monsoon regaining its impact on CONUS. A secondary factor is the low-pressure trough coming down from the Great Lakes which will stay to the East of the Rocky Mountains but as it clashes with this very moist near-tropical air the result will be precipitation. You can see part of the set-up in this graphic.
The below graphic 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 currenlty is and is going.
Looking at an even 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 Eastern Pacific Subtropical High is no longer serving as a block to all storms attempting to move from the Pacific into CONUS. So for at least this week, we do not have to denigrate this feature by calling it the RRR. But it still plays a role in the positioning of the Four Corners High and thus the strength and location of the Monsoon. The real action remains north of the Great Lakes in Canada where there is a strong Low that is penetrating CONUS and to a large extent dominating weather for a large part of CONUS. .
Outlook Days 6 – 14 (but only showing the 8 – 14 Day Maps)
Here is the Temperature Outlook for August that was released on July 16, 2015
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 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 July 27 (it updates each day), it suggests that August may start out to be warmer for the Southwest than previously anticipated and cooler for a large part of the Northern Tier especially the Great Lakes area.
Here is the Precipitation Outlook for August that was released on July 16, 2015
Below is the current 8 – 14 Day Precipitation Outlook which will auto-update daily and thus be current when you view it. And again remember that this map shows only seven days and the 6 – 14 Day map is available on Page II of this report.
It looks like the Monsoon is forecast to resume.
Here are excerpts from the NOAA discussion released today July 27, 2015.
6-10 DAY OUTLOOK FOR AUG 02 – 06 2015
TODAY’S ENSEMBLE MEAN AND DETERMINISTIC SOLUTIONS ARE IN GOOD AGREEMENT ON THE FORECAST 500-HPA MEAN CIRCULATION PATTERN OVER NORTH AMERICA AND VICINITY FOR THE 6-10 DAY PERIOD. THERE IS GOOD CONSENSUS FOR A 500-HPA RIDGE TO BE LOCATED OVER THE WESTERN CONUS, WITH A DOWNSTREAM TROUGH LOCATED NEAR THE GREAT LAKES. MOST MODEL SOLUTIONS PREDICT A RIDGE OVER THE BERING SEA AND A TROUGH NEAR THE GULF OF ALASKA. POSITIVE 500-HPA HEIGHT ANOMALIES ARE GENERALLY FORECAST OVER ALASKA AND THE WESTERN CONUS WHILE BELOW NORMAL HEIGHTS ARE PREDICTED OVER MUCH OF THE EASTERN CONUS. TODAY’S OFFICIAL 500-HPA BLEND FAVORS THE ENSEMBLE MEAN SOLUTIONS AND IS COMPOSED OF SIGNIFICANT CONTRIBUTIONS FROM THE ECMWF, GFS, AND CANADIAN ENSEMBLE MEANS.
BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE NORTH-CENTRAL CONUS AND THE GREAT LAKES REGION DUE TO THE TROUGH PREDICTED OVER EASTERN NORTH AMERICA. CONVERSELY, THERE ARE ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WESTERN CONUS AND ALASKA UNDERNEATH PREDICTED ABOVE NORMAL HEIGHTS. ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE ALSO INDICATED FOR MUCH OF THE SOUTHERN TIER OF THE CONUS CONSISTENT WITH BIAS CORRECTED TEMPERATURES FROM THE ECMWF ENSEMBLES AND WITH GEFS REFORECAST GUIDANCE.
GEFS REFORECAST GUIDANCE AND PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLES INDICATE FAVORABLE CONDITIONS FOR ABOVE-MEDIAN PRECIPITATION FOR MUCH OF THE INTERIOR WEST INCLUDING THE GREAT BASIN, CENTRAL ROCKIES, AND PARTS OF THE SOUTHWEST. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR PARTS OF THE GREAT LAKES REGION EXTENDING TO NORTHERN NEW ENGLAND IN ASSOCIATION WITH THE TROUGH PREDICTED OVER EASTERN NORTH AMERICA. BELOW MEDIAN PRECIPITATION IS FAVORED BEHIND THE TROUGH AXIS FOR PARTS OF THE NORTHERN PLAINS. PROBABILITIES FOR ABOVE-MEDIAN PRECIPITATION ARE ENHANCED FOR PARTS OF THE SOUTHEASTERN CONUS IN ASSOCIATION WITH A PREDICTED FRONTAL BOUNDARY EARLY IN THE PERIOD. BELOW MEDIAN PRECIPITATION IS FAVORED FOR PARTS OF THE SOUTHERN PLAINS AND SOUTHERN MISSISSIPPI VALLEY CONSISTENT WITH GEFS REFORECAST GUIDANCE, NAEFS GUIDANCE, AND PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS. ENHANCED PROBABILITIES OF BELOW MEDIAN PRECIPITATION ARE ALSO INDICATED FOR MUCH OF ALASKA AND THE PACIFIC NORTHWEST UNDERNEATH PREDICTED ABOVE NORMAL 500-HPA HEIGHTS.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD AGREEMENT AMONG MODELS.
8-14 DAY OUTLOOK FOR AUG 04 – 10 2015
TODAY’S MODEL FORECASTS FOR THE 8-14 DAY 500-HPA CIRCULATION ARE QUITE SIMILAR TO AND REFLECT A SLIGHT PROGRESSION OF THE OVERALL PATTERN OF THE 6-10 DAY MEAN. A MEAN TROUGH IS PREDICTED OVER EASTERN NORTH AMERICA CENTERED NEAR THE EASTERN GREAT LAKES WHILE A RIDGE CENTERED NEAR THE ROCKIES IS FORECAST OVER THE WESTERN CONUS. IN ADDITION, POSITIVE HEIGHT ANOMALIES CONTINUE TO BE FORECAST FOR MOST OF ALASKA. THE WEEK TWO MANUAL 500-HPA BLEND IS COMPOSED PRIMARILY OF THE ENSEMBLE MEAN SOLUTIONS AND IS BASED, IN PART, ON CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.
THE PERSISTENT TROUGH OVER THE EASTERN CONUS ELEVATE CHANCES FOR BELOW-NORMAL TEMPERATURES FOR A LARGE PORTION OF THE NORTH-CENTRAL AND NORTHEASTERN CONUS. FARTHER TO THE SOUTH, ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE SOUTHEASTERN CONUS CONSISTENT WITH GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE ECMWF ENSEMBLE MEMBERS. CHANCES ARE ENHANCED FOR ABOVE-NORMAL TEMPERATURES IN MUCH OF THE WEST UNDER THE EXPECTED 500-HPA RIDGE. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR MUCH OF ALASKA UNDERNEATH PREDICTED ABOVE NORMAL 500-HPA HEIGHTS.
GEFS REFORECAST GUIDANCE AND PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS CONTINUE TO FAVOR ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE INTERIOR WEST. NEAR TO ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE EASTERN SEABOARD IN ASSOCIATION WITH THE TROUGH PREDICTED OVER EASTERN NORTH AMERICA. HOWEVER, FORECAST PROBABILITIES ARE LOW FOR THIS REGION DUE TO CONFLICTING GUIDANCE BETWEEN THE WETTER NAEFS AND THE DRIER SOLUTIONS FROM THE GEFS REFORECAST AND ECMWF PRECIPITATION ESTIMATES. TOOLS ARE IN BETTER AGREEMENT OVER THE SOUTHERN PLAINS, WHERE BELOW MEDIAN PRECIPITATION IS FAVORED. BELOW MEDIAN PRECIPITATION IS ALSO FAVORED FOR PARTS OF THE UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES BEHIND THE TROUGH AXIS PREDICTED OVER EASTERN NORTH AMERICA. TOOLS ARE IN GOOD AGREEMENT IN FAVORING BELOW MEDIAN PRECIPITATION FOR MUCH OF ALASKA UNDERNEATH PREDICTED ABOVE NORMAL 500-HPA HEIGHTS.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO RELATIVELY GOOD AGREEMENT AMONG MODELS OFFSET BY DISAGREEMENTS AMONG THE SURFACE TOOLS (PARTICULARLY FOR PRECIPITATION).
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.
|1954 July 22||La Nina||Neutral||Neutral|
|1954 July 23||La Nina||Neutral||Neutral|
|1963 July 19||El Nino||–||–||Modoki Type I|
|1964 August 1||La Nina||–||–|
|1981 August 1||Neutral||+||–|
|1996 July 17||Neutral||+||Neutral|
|1996 July 18||Neutral||+||Neutral|
|2001 July 31||Neutral||–||+|
The first thing I noticed is that today is July 27 and these are analogs centered on dates 3 or 4 days ago which have a fairly narrow span from July 17 to August 1. This suggests that we are going to have typical weather for this time of the year. What is strange is that there is only one analog associated with an El Nlino and a Modoki at that. Thus suggests to me that the current El Nino is not going to impact our weather significantly over the next two weeks. The ocean phases associated with the analogs this week provide no clues and that is often the case in the Summer. 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.
|Date||Current Reading||30-Day Average||90 Day Average|
|21 July 2015||-0.0||-18.43||-11.10|
|22 July 2015||-7.0||-17.71||-11.11|
|23 July 2015||-11.3||-17.14||-11.3|
|24 July 2015||-14.4||-16.59||-11.58|
|25 July 2015||-16.2||-15.66||-11.8|
|26 July 2015||-12.5||-14.44||-11.83|
|27 July 2015||-17.1||-13.66||-11.85|
This past week has been favorable for the continued development of the current El Nino. The 30-day average, which is the most widely used measure, on July 27 was reported as being -13.66 which is clearly an El Nino reading although not as extreme as the prior week as some of the earlier very extreme values dropped out of the 30 day running average. The 90-day average also is solidly in El Nino territory at -11.85. 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. There has been another mid-Pacific wind burst in the Date Line to 160W area.
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 along the Equator is no longer shown on this graphic as it occurred a few weeks ago. The main impact of that Kelvin Wave is already close to 140W and about to exit the Nino 3.4 ONI measurement area.
But as you can see there 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. I think we can also see the beginning of the next upwelling wave off to the left and in other graphics which may signal the playing out of this series of Kelvin Waves. But continued SOI activity could create yet another Kelvin Wave although I think the Pacific Warm Pool at this point has been substantially depleted. The ENSO “battery” is weakening and will need a La Nina to recharge itself.
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 beyond 140W but not quite to 150W. 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 to 170W where the westerly wind burst occurred and where we see above the beginning of one more Kelvin Wave. So far it seems to be fairly minor compared to what has occurred in prior months but that might change. It certainly has delayed the movement of the leading edge of the warmer water to 170W. At that point we are likely to see the ONI decline week to week. 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. Water is a very good insulator: I believe it has the second highest specific heat capacity of all known substances. 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 the Sourthern 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 but I am skeptical because I see it as rising to the east of the ONI measurement area and not being counted.
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 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 or turns back into a Modoki. I believe that process has already begun.
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 yet 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 1.5C+ anomaly has just about reached 170W but not quite due to the new Kelvin Wave. When the leading edge of the water areas move beyond 170W, the anomalies in the western parts of Nino 3.4 are likely to start to decline. But at the same time, the subsurface warm water is coming to the surface and that makes the anomalies in the eastern part of Nino 3.4 larger.
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 Nino in the Fall. So we have to watch what happens carefully..
For my own amusement, 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 July 27 in the afternoon working from the July 26 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.
|Anomaly Segment||Estimated Anomaly|
|A. 170W to 160W||1.5|
|B. 160W to 150W||1.6|
|C. 150W to 140W||1.6|
|D. 140W to 130W||1.6|
|E. 130W to 120W||1.7.|
|Total divided by five subregions i.e. the ONI||(8.0)/5 = 1.6|
My estimate of the Nino 3.4 ONI is now 1.6. NOAA has today reported the weekly ONI as being 1.6 a slight decline from that which was reported last week and identical with my rough calculation.Curiously the decrease in the ONI is mostly due to the subsurface water in the Eastern Pacific not backing up as much to the west this past week. 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. 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 which I have discussed in previous weeks and I will not repeat the same interpretation over and over again. Today I see a slight tendency for the areas east of Nino 3.4 to be less warm than in prior weeks. That could be an indication of the process slowly working its way through the process of disposing of the subsurface very warm water.
You will not see the ONI substantially decline until the warm water over at 180, The International Date Line, has moved east of 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.or more. I personally believe they have overestimated the peak value of the ONI for this El Nino. 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 for purposes of estimating the impacts.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
First the 90-Day
And the 30-Day which shows the more recent impacts
You can see the precipitation impact extending further to the east (both the impacts to the nothern tier and the mid latitude and Texas with perhaps 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. But it appears to be a coherent pattern rather than random.
Pulling it All Together
I though it might be useful to put this warm event into historical context. Here is a history of ONI readings.
You can see that the 2014/2015 Wam Event which did not quite meet the criteria of being an El Nino has been followed by another warm event (the two are probably part of the same warm event but NOAA does not have the teminology to describe it that way) and so far there is nothing especially noteworthy about this warm event although we will know more after it is history. You can see that warm events follow cool events (La Nina when extreme) which are then followed by a warm event and then a cool event ad infinitum. In recent years we have had more cool events than warm events which explains the Southwest Drought in the U.S. (too complex for the media to comprehend) and perhaps we are headed into a period with a higher ratio of warm events to cool events which will result in a wetter Southwest (and a boost to average Global Temperarture). NOAA keeps on adusting the base line so Global Warming does not impact the look of this graphic. The deficiency of this graphic is that it does not differentiate between Traditional Warm Events and Modoki (Central Pacific only) Warm events.
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. Actually the JAMSTEC model is not very different from my assessment. 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 mild La Nina.
Useful Related Reading
Written by Sig Silber
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.