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posted on 13 September 2016

September 12, 2016 Weather and Climate Report - Frozen in Time

Written by Sig Silber

There is a lot of uncertainty about details of the forecast for the next two weeks.  But the pattern for CONUS has remained remarkably the same other than for the occasional Tropical Event. The Southwest has been cooler than climatology and almost everywhere else has been warmer than climatology. The Northwest has been dry and a wet anomaly anchored in New Mexico and Texas expanded and contracted northeast towards the Great Lakes. This pattern is expected to continue for at least another month.

 weather.caption

It is difficult to know how best to organize a report that is attempting to convey a lot of information all of which is interconnected but some of which may be of more interest to different readers. I am organizing this report differently this week and if readers have feedback please send it to ssilber1@juno.com.

A. Focus on Alaska and CONUS (all U.S. except Hawaii)

I have never presented the below graphic before but I am showing it today to support the statement in the lead paragraph to this report.

September 12, 2016 Atmospheric Pattern

Not to go into a lot of detail but you can see that the pattern of Highs (reds) and lows (blues) has been pretty similar since the July 12 - 26 view and not that much changed from that one actually. The map is hard to read but you can see the U.S. underneath the superimposed pattern of the height anomalies and you can see that there has been a High off the West Coast, A Low along the West Coast and a High along the East Coast. It makes the life of weather forecasters easy but this graphic is showing 20N to 70N so it does not cover the tropics where our variability has been coming from. 

Let's Focus on the Current (Right Now to 5 Days Out) Weather Situation.

First, here is a national animation of weather fronts 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.

current highs and lows

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.

U.S.  3 Day to  7 Day Forecasts

You can enlarge the below daily (days 3 - 7) weather maps by clicking on Three Day or  Four Day or Five Day or Six Day or Seven Day 

Short term forecasts

This graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.

 Center for Western Weather and Water Extremes, Scripps/UCSD.

Notice that there is not a lot of moisture around CONUS.      .

Here is the seven day precipitation forecast. More information is available here.

Seven Day WPC Quantitative precipitation forecast

What you are seeing here is projected subtropical moisture impacting the Southwest and Gulf Coast. There is some uncertainty with respect to whether or not this pattern will materialize.

The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients.This graphic auto-updates so when you look at it you will see NOAA's latest thinking. The speed at which these troughs and ridges travel across the nation will determine the timing of weather impacts. This graphic auto-updates I think every six hours and it changes a lot. Because "Thickness Lines" are shown by those green lines on this graphic, it is a good place to define "Thickness" and its uses. The 540 Level general signifies equal chances for snow at sea level locations. I am leaving this explanation in the report but it may not be very significant until next October or so which now is less than two months away. .

7 Day 500 MB Geopotential Forecast

Not sure one can rely on this graphic to locate the Four Corners High as it seems to be on vacation this Summer. If it showed up on this graphic, one could draw or imagine a one-inch or so in radius circle overlain on the Four Corners High with an arrow showing the wind pattern is clockwise (anticyclone). One can then imagine where moisture might be being drawn into the edge of the High Pressure System.
Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.
What you can see very clearly in the above is the Trough near the Great Lakes and another one harder to see perhaps on the West Coast especially California. There is no sign of a Four Corner's High.

The graphic below is similar to the above but with more detail which has pros and cons. It highlights the forecasted surface Highs and the Lows re air pressure on Day 6 (the Day 3 forecast is available on Page II of this Report. It you go there, hit your return button to get back to this report). This graphic also auto-updates.

Day 6 Weather Forecast

The Aleutian Low is not the controlling factor during the summer. But it is quite visible right now (well it was yesterday) and fairly strong. We are transitioning from Summer to Fall and Winter. We will start reporting on the Aleutian Low soon.
The High Pressure off of California, the familiar RRR, is here and quite large and strong. The RRR continues to do a good job of protecting the West Coast from Pacific storms and also providing northerly winds for California. It looks like it will not extend far enough south to block TS (now Hurricane) Orlene from heading west and turn it north into CONUS as Newton did. Recently, I provided this  K - 12 write up that provides a simple explanation on the importance of semipermanent Highs and Lows and another link that discussed possible changes in the patterns of these highs and lows which could be related to a Climate Shift (cycle) in the Pacific or Global Warming. Remember this is a forecast for Day 6. It is not the current situation.

Eastern Pacific 

The above is the Eastern Pacific again a 24hr loop of recent readings. It does a good job of showing what is going on right now. The southwest winds approaching Baja California are of some interest.
Below is the current water vapor Imagery for North America. 

 Water Vapor Imagery

Tonight, Monday evening September 12 (and this is the current situation not an animation of recent history), as I am looking at the above graphic, there is not much activity anywhere in CONUS other than Texas and Florida.

This graphic (which is a bit redundant with the above) updates automatically so it most likely will look different by the time you look at it as the weather patterns, except for the Southwest Monsoon, are moving from west to east. It highlights the tropical activity

Eastern Pacific Tropical Storms

For CONUS, the above graphic is more specific and near term with interpretation and has a focus on tropical storms.  It does not cover as wide an area e.g. it does not cover the Western Pacific or the Atlantic far east of the U.S. It is actually a convenient graphic for tracking the Southwest Monsoon. As you can see, there continues to be a single band of tropical moisture and it is now down by Panama and Costa Rica. In general the tropical storms originating off of the west coast of Central American are not curving around and coming aground but heading out to sea rapidly. Newton obviously was an exception to that pattern and I think the general rule right now is that such storm being generated further north can get trapped inside of the RRR and be steered inland but storms being generated closer to the Equator move west without difficulty. There is subtropical moisture that creates the occasional thunderstorm. For now it is the tail end of a minimal Monsoon (The Phoenix NWS refers to the Monsoonal situation as "High Grade", "Low Grade" and "No Grade". This is definitely somewhere between a "Low Grade" and a "No Grade" Monsoon at this point re Arizona and New Mexico. The College Park Md NOAA Headquarters location predicts continued Monsoonal Activity but the local forecasters in Arizona and New Mexico are not so sure. We should expect some minor intrusions of the Monsoonal Moisture Boundary (MMB) into CONUS but these events are likely to be brief and impact mostly the areas very close to Mexico and may favor Southern New Mexico and Western Texas. The latitude of the prevailing westerlies  and  the track of the ongoing west coast troughs and the location of the Great Lakes Trough. These three things are interconnected and  will determine if there is a lot of time with southerly or southwesterly winds which are what allows the subtropical moisture to move from Mexico into CONUS.

Looking at the current activity of the Jet Stream.

The sub-Jetstream level intensity winds shown by the vectors in this graphic are very important. You can see how Subtropical Moisture can be brought up into CONUS from Mexico. But this is the graphic from one of the forecasting models and they do not all agree. So a slight shift of the pattern to the north or to the south makes a big difference with respect to the potential for moist air from Mexico to enter CONUS.

Current Jet Stream

air pressure and altitude
Re the above, H8 is the height of the 850 millibar level, H7 is the 700 mb level, H5 is the 500 mb level, H3 is the 300 mb level. So if you see those abbreviations in a weather forecast you will know what they are talking about.
Also the ideal situation is for the mid-level to be cooler than the Boundary Level. You need to have a steep decline in temperature at higher altitudes for the atmosphere to be unstable and create a significant number of healthy clouds and storms. The Devil is in the details. So there can be very higher PWATs i.e. the amount of moisture in the water column at a particular location but still no precipitation if there is no convection. A PWAT of 1.2 inches of water is sort of a summer trigger point,  Levels much higher than 1.2 inches of water could lead to hail. But in the absence of instability, nothing happens. Those westerlies are one reason why there has been less instability than optimal for the Southwest Monsoon to be productive. And now with September almost here the PWAT's are down under 1.2 inches so we not only have a "low Grade Monsoon" we also have a "Dry Monsoon".

Below is the forecast out five days.

You can see the Western Trough dropping down.  As drawn, you can see that tropical moisture from Mexico will have an easy time entering CONUS. But this is the results from one forecasting model the GFS and the various models are disagreeing right now. The GFS even shows some Jet Stream activity to reinforce the pattern. Again this is only the interpretation of one model and NOAA has indicated that the models right now are not agreeing very well. So one has to assign this a lower probability to work out as shown than when the models agree.

Jet Stream Five Days Out

Not all weather is controlled by the Jet Stream (which is a high altitude phenomenon) but it does play a major role in steering storm systems. In some cases however a Low-Pressure System becomes separated or "cut off" from the Jet Stream. In that case it's movements may be more difficult to predict until that disturbance is again recaptured by the Jet Stream.

To see how the pattern is projected to evolve,  please click here. In addition to the shaded areas which show an interpretation of the Jet Stream, one can also see the wind vectors (arrows) at the 300 Mb level.

This longer animation shows how the jet stream is crossing the Pacific and when it reaches the U.S. West Coast is going every which way.

Click here to gain access to a very flexible computer graphic. You can adjust what is being displayed by clicking on "earth" adjusting the parameters and then clicking again on "earth" to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns. This amazing graphic covers North and South America.

Four- Week Outlook

I am going to show the three-month SON Outlook (for reference purposes), the Updated Outlook for the single month of September, the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 -  4 Experimental Outlook. 

First - Temperature

Here is the Three-Month SON Temperature Outlook issued on August 18, 2016:

SON Temperature Outlook Issued on August 18, 2016

Here is the Temperature Outlook for September which was updated on August 31, 2016

September Updated Temperature Outlook Issued on August 31, 2016

 6 - 10 Day Temperature Outlook

6 - 10 Day Temperature Outlook

8 - 14 Day Temperature Outlook   

8-14 Day Temperature Outlook

Looking further out.

Experimental Week 3-4 Temperature Outlook

As I view these maps on September 12 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday), it appears that through October 7, the pattern during the second half of September will be warm everywhere other than where subtropical moisture is forecast to enter CONUS from Mexico. That pattern is expected to continue through the first week of October.

 Now - Precipitation 

Here is the three-month SON Precipitation Outlook issued on August 18, 2016 21, 2016:

SON Precipitation Outlook Issued on August 18, 2016

And here is the Updated Outlook for September Precipitation Issued on August 31, 2016

September 2016 Early Precipitation Outlook Updated on August 31, 2016

6 - 10 Day Precipitation Outlook

6 - 10 Day Precipitation Outlook

8 - 14 Day Precipitation Outlook 

Current 8 - 14 Day Precipitation Outlook

Weeks 3 and 4 Experimental Forecast..

As I view these maps on September 12 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday), it looks like precipitation leading up to October 7 is tending for the second half of September to be dry in the Northwest extending to the east and wet in New Mexico and Texas extending to the Great Lakes and the Northeast with the pattern continuing into the first week of October but with a dry Southeast Coast other than the tip of Florida developing.

Here is the NOAA discussion released today September 12, 2016.

6-10 DAY OUTLOOK FOR SEP 18 - 22 2016

TODAY'S NUMERICAL MODEL SOLUTIONS ARE IN RELATIVELY POOR AGREEMENT ON THE 500-HPA FLOW PATTERN PREDICTED OVER THE FORECAST DOMAIN. THE ENSEMBLE MEAN SOLUTIONS FROM THE GFS, CANADIAN, AND ECMWF PREDICT A TROUGH NEAR THE BERING STRAIT AND BELOW NORMAL HEIGHTS OVER MOST OF ALASKA. FARTHER TO THE SOUTH, THE ECMWF-BASED SOLUTIONS FEATURE AN ENHANCED JET AND BELOW NORMAL HEIGHTS NEAR THE PACIFIC NORTHWEST WHILE THE GFS- AND CANADIAN-BASED SOLUTIONS FORECAST ABOVE NORMAL HEIGHTS ACROSS THE NORTHWESTERN CONUS. FARTHER DOWNSTREAM, MOST MODEL SOLUTIONS FORECAST THE WESTERLIES TO BE NORTH OF THEIR CLIMATOLOGICAL POSITION, RESULTING IN PREDICTED ABOVE NORMAL HEIGHTS ACROSS THE NORTHERN TIER OF THE CONUS. SUBTROPICAL RIDGING AND NEAR NORMAL HEIGHTS ARE FORECAST ACROSS MUCH OF THE SOUTHERN TIER OF THE CONUS. ENSEMBLE SPREAD IS VERY HIGH OVER MUCH OF THE CONUS INDICATING LARGE DIFFERENCES AMONG INDIVIDUAL ENSEMBLE MEMBERS. DUE TO THIS UNCERTAINTY, TODAY'S MANUAL 500-HPA HEIGHT BLEND IS COMPOSED PRIMARILY OF THE ENSEMBLE MEAN SOLUTIONS. THE GREATEST WEIGHTS WERE GIVEN TO THE GFS ENSEMBLE MEANS DUE, IN PART, TO RELATIVELY HIGH ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.

ABOVE-NORMAL TEMPERATURES ARE FAVORED OVER MUCH OF THE CONUS UNDERNEATH PREDICTED ABOVE NORMAL HEIGHTS. HOWEVER, NEAR NORMAL TEMPERATURES ARE FAVORED  FOR PARTS OF THE SOUTHERN HIGH PLAINS AND SOUTHWEST DUE TO THE POTENTIAL FOR INCREASED CLOUD COVER AND PRECIPITATION TO AFFECT THIS REGION. THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR PARTS OF NORTHERN ALASKA UNDERNEATH PREDICTED BELOW NORMAL HEIGHTS. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF SOUTHERN ALASKA (ESPECIALLY FOR COASTAL LOCATIONS) IN ASSOCIATION WITH ABOVE NORMAL SEA SURFACE TEMPERATURES IN ADJACENT WATERS. 

THERE ARE ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR SOUTHERN  AND EASTERN ALASKA IN ASSOCIATION WITH TROUGHS PREDICTED OVER THE BERING STRAIT AND THE GULF OF ALASKA. BELOW MEDIAN PRECIPITATION IS FAVORED ACROSS MUCH OF THE NORTHERN TIER OF THE CONUS FROM THE GREAT LAKES WESTWARD UNDERNEATH  PREDICTED ABOVE NORMAL HEIGHTS. CONVERSELY ABOVE MEDIAN PRECIPITATION IS  FAVORED ALONG THE EASTERN SEABOARD EXTENDING TO THE SOUTHERN PLAINS DUE TO A  PREDICTED FRONTAL BOUNDARY AND ASSOCIATED SHORTWAVE ENERGY.   

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO  VERY HIGH MODEL SPREAD OVER MUCH OF THE CONUS.

8-14 DAY OUTLOOK FOR SEP 20 - 26 2016 

TODAY'S WEEK-2 ENSEMBLE MEAN SOLUTIONS CONTINUE TO FORECAST A TROUGH NEAR THE BERING STRAIT AND BELOW NORMAL HEIGHTS OVER WESTERN ALASKA. DOWNSTREAM OF THIS TROUGH, RIDGING IS FORECAST OVER PARTS OF WESTERN NORTH AMERICA RESULTING IN PREDICTED ABOVE NORMAL HEIGHTS OVER MUCH OF NORTHWESTERN CONUS. SHALLOW, CYCLONIC FLOW IS FORECAST DOWNSTREAM OF THIS RIDGE ACROSS MUCH OF THE NORTHERN  TIER OF THE CONUS. HOWEVER, MODELS DISAGREE AS TO THE LOCATION OF THE MEAN TROUGH AXIS AS THE CANADIAN ENSEMBLE MEAN FORECASTS THE TROUGH AXIS NEAR THE GREAT LAKES WHILE THE GFS ENSEMBLE MEANS HAVE IT MUCH FARTHER TO THE WEST OVER THE NORTHERN PLAINS. SUBTROPICAL RIDING AND NEAR NORMAL HEIGHTS ARE FORECAST OVER MUCH OF THE SOUTHERN TIER OF THE CONUS. AGREEMENT AMONG SUCCESSIVE RUNS OF THE DETERMINISTIC GFS IS POOR TODAY AND ENSEMBLE SPREAD IS HIGH. DUE TO THESE DISAGREEMENTS, TODAY'S WEEK-2 500-HPA MANUAL HEIGHT BLEND CONSISTS PRIMARILY OF THE ENSEMBLE MEAN SOLUTIONS. THE GREATEST WEIGHT WAS GIVEN TO THE 0Z CANADIAN ENSEMBLE MEAN DUE, IN PART, TO RELATIVELY HIGH ANALOG CORRELATIONS.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE CONUS UNDERNEATH PREDICTED ABOVE NORMAL HEIGHTS. HOWEVER, NEAR NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF THE SOUTHERN HIGH PLAINS AND SOUTHWEST CONSISTENT WITH BIAS CORRECTED TEMPERATURES FROM THE CANADIAN, GFS, AND ECMWF ENSEMBLE MEMBERS. THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR SOUTHEASTERN MAINLAND ALASKA AHEAD OF A TROUGH FORECAST NEAR THE ALASKA PENINSULA AND FOR SOUTHERN COASTAL ALASKA FROM THE ALEUTIANS TO THE PANHANDLE DUE TO ABOVE NORMAL SSTS.

ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE EAST-CENTRAL CONUS UNDERNEATH PREDICTED CYCLONIC FLOW. CONVERSELY, BELOW MEDIAN PRECIPITATION IS  FAVORED FOR MUCH OF THE NORTHWESTERN CONUS IN ASSOCIATION WITH PREDICTED RIDGING AND ABOVE NORMAL HEIGHTS. ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION ARE INDICATED FOR PARTS OF THE NORTHEASTERN CONUS CONSISTENT WITH GEFS REFORECAST GUIDANCE. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF SOUTHERN ALASKA IN ASSOCIATION WITH A TROUGH PREDICTED NEAR THE ALASKA PENINSULA.

 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO HIGH MODEL SPREAD AND UNCERTAINTY.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  SEPTEMBER 15

Some might find this analysis interesting as the organization which prepares it looks at things from a very detailed perspective and their analysis provides a lot of information on the history and evolution of ENSO events.

Analogs to the Outlook.

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 regularly analyzing this second set of information. The first set which is what I am using today applies to the 5 and 7 day observed pattern prior to today. The second set, which I am not using, relates to the correlation of the forecasted outlook 6 - 10 days out with similar patterns that have occurred in the past during the dates covered by the 6 - 10 Day Outlook. The second set of analogs may also be useful information but they put the first set of analogs in the discussion with the second set available by a link so I am assuming that the first set of analogs is the most meaningful and I find it so.

Day

ENSO

Phase

PDO AMO

Other Comments

Aug 31, 1952 Neutral - +  
Sept 21, 1965 El Nino + (t) - Possibly a Modoki
Sept 18, 1983 Neutral + - After the third most powerful El Nino
Sept 23, 1985 Neutral + -  
Aug 31, 1993 Neutral + -  
Sept 19, 2000 La Nina - + (t) The long La Nina that followed the MegaNino
Aug 30, 2004 El Nino + + Modoki Type II
Sept 7, 2007 La Nina - (t) +  

(t) = a month where the Ocean Cycle Index has just changed or does change the following month.

One thing that jumped out at me right away was the spread among the analogs from August 30 to September 23 which is just three days over three weeks which is a small spread. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, is about September 11 These analogs are centered on 3 days and 4 days ago (September 8 or 9). So the analogs could be considered pretty much in sync with the calendar perhaps three or four days later (meaning that we will be getting weather that normally would occur three or four days later than it is forecasted to occur) with a small spread which to me adds some confidence in the forecast in the sense only that it is not very inconsistent with the time of the year and the analogs if correctly selected (a big assumption) are also reasonably consistent with this time of the year.

I think NOAA would appreciate it if I said that these analogs are not a substitute for their very sophisticated forecasting software and I am not suggesting that they are. I present them partially for curiosity purposes but also to see how current conditions correlate with medium and low frequency cycles. The medium frequency cycle I track is ENSO and the two low- frequency cycles I track are the PDO and AMO. When I see that forecasts are consistent with the current phases of these cycles (as represented by the analogs), that seems very suggestive to me that our weather is probably fairly easy to forecast. If the analogs are all over the place then I have to wonder if the forecasts are good or if our weather is just not related to these cycles. That certainly can be the case. So I am doing some research here and you are seeing how I look at things. I hope you find it interesting.

There is this time two El Nino Analogs (why are there any?), two La Nina Analogs, and four ENSO Neutral Analogs. The phases of the ocean cycles in the analogs are suggestive of McCabe Condition A and D which are opposites which is consistent with the difficulty NOAA has indicated with their 6 - 14 Day Outlook.

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. One of the major reasons that I write this weather and climate column is to encourage a more long-term and World view of weather.

McCabe Maps modified to include the subtitles

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.

Recent CONUS Weather

This is provided mainly to see the pattern in the weather that has occurred in recent months. Because it is now September, I have now removed the June and June - April - May - June 90 Day Graphics. They are available in Part II of this Report - If you click to go there and take a look, hit your "Return Key" to return to this article. 

Let's look at the temperature and precipitation anomalies for the 30 days ending July 30, 2016

August 1, 2016 30 Day temperature and precipitation departures.

And now we looking at August. Here are the 30 Days ending September 3.

September 3, 2016 30 Day temperature and precipitation departures.

And the 90 days

September 3, 2016 90 Day Temperature and Precipitation Departures

You can see the three month period was dry in the West and warm in the East.

And now the 30 days ending September 10, 2016.

September 10, 2016 30 Day temperature and precipitation departures.

For comparison purposes, you have to look up two graphics as the one immediately above is the 90 rather than the prior 30 day period. Remember that new 30 day period which only differs from the prior 30 day graphic by the addition of seven days and removing the first seven days of the prior 30 day average.
What we see is not much change. I am a bit surprised as I thought the recent storm, Hermine, would have added to the average precipitation totals for Northern Florida and parts north but not so much. Not much talk of a MegaDrought in Texas these days. And that pattern of a wet Texas off and on extending up to the Great Lakes looks to continue.

B. Beyond Alaska and CONUS Let's Look at the World which of Course also includes Alaska and CONUS

Click Here for a World Weather Forecast produced by the Australian Bureau of Meteorology. Unfortunately I do not know how to extract the map only so to see it you have to click where I said "click here". You can adjust the settings to show Temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool. 

Sea Surface Temperature (SST) Departures from Normal for this Time of the Year i.e. Anomalies

My focus here is sea surface temperature anomalies as they are one of the two largest factors determining weather around the World.

And when we look at the current Sea Surface anomalies below, we see a lot of them not just along the Equator related to ENSO.

Daily SST Anomaly

Remember this discussion is all about anomalies not absolute temperatures...so it is deviation from seasonal norms.
The waters off of Japan remain warm. South of Kamchatka Siberia the color on the graphic is really intense. The Indian Ocean is now basically all cool. The southern coast of Australia is cool but a very small area on the Southeast Coast is a bit warm. Water northwest of Australia is warm but not very much although the four week change graphic below will suggest it is getting a bit warmer.  The waters south of Africa are warm to the west but a bit cool to the east.
The overall Northern Pacific is perhaps PDO Positive ((the horseshoe pattern with the cool anomaly (barely visible) inside the horseshoe shape)) and may not record as PDO+ The Pacific Decadal Oscillation (PDO) Index rose to 2.4 in March which with El Nino fading may be significant. It was up to 2.62 in April but eased to 2.35 in May and then to +0.78 in June and then down to +0.18 for July and then recorded a negative value of -.66 for August and the July value was adjusted to +0.11. That would make the PDO now NEGATIVE. The question remains about the PDO. Is it acting independently of the El Nino or is this the change from PDO- to PDO+ (until August) which would signal a multi-decadal change in the Pacific. I anticipated that the PDO would turn negative as the La Nina gained control and it has.But is that just temporary.  Here is the list of PDO values.
The Black and Caspian seas are warm. So is the Mediterranean.
The water directly west of South America is not showing much of a strong La Nina pattern even though El Nino is history. There is a narrow cool anomaly in the Pacific right along the Equator in the La Nina Measurement Area but it does not extend very far north or south of the Equator. It has been gradually stretching west. The connection to Ecuador is weak.  It is a La Nina pattern but too weak yet to qualify as an official La Nina and probably will remain borderline La Nina through the winter.  It may ultimately turn out to be a La Nina Modoki i.e. shifted to the west more than the typical La Nina but simply Neutral seems more likely. The water off the West Coast of Central America is warm but less so than recently. Further north, the Gulf of Alaska is quite warm. The Pacific being warm north of 40N remains the most impressive feature of the overall pattern.
The water off the East Coast of CONUS is very warm covering a large area and extending quite far to the east and we see the impact in terms of actual formation of tropical storms. The list of Atlantic Multidecadal Oscillation (AMO) values can be found here. Further north in the Atlantic east of Newfoundland the North Atlantic is becoming warmer than normal and there is hardly any cool anomaly. The cool anomaly off shore of Northwest Africa is now a small warm anomaly  but there is not continuity over to the Caribbean so Hurricane formation may not be that prevalent in September. The waters north of Antarctica East of South America are uniformly colder than climatology and we again see the warm anomalies north of that pattern. I have some additional commentary on this static analysis of the anomalies below where I examine the four-week change in these anomalies.
Since these are "departures" or "anomalies", it is not a seasonal pattern that is being shown it is the changes from what we would expect on a seasonal basis. It is important to understand that and interpret my comments above in the context of anomalies not absolute temperatures.

Below I show the changes over the last month in the Sea Surface Temperature (SST) anomalies.

Comparing a four-week graphic to a prior four-week graphic is always tricky since only 25% of the data has changed and I am not showing the former graphic (it is in last week's report). I add the new one to my draft report, compare and comment on the change and then delete the old one to keep this report to a manageable size. Also it is important to recognize that what you see in this graphic is the change in the anomaly. So blue means either cooler or less warm. Red means warmer or less cool. So you have to refer to the graphic above this one to really interpret this graphic as what we are seeing here is the change in the anomalies. What we see in this graphic is four weeks of change not the current absolute anomalies which are shown in the above graphic. It is not derivatives in the mathematical sense but deltas. They are somewhat similar. The graphic above this one has no time component. It is simply the deviation from climatology and this graphic below shows the four week change in the deviation from climatology. So it is a bit like the first (graphic above) and second (graphic below) derivatives but not exactly. I take it a step further by comparing this weeks version of the graphic to the prior week and report on the differences below.  

September 12, 2016 Four Week Change in Weekly SST Anomalies

What I see as I look at both last week's version of this graphic and the current one (before deleting the prior version) is warming in the Southern Hemisphere especially south of Australia. But there is cooling off the African Coast. In the Northern Hemisphere the waters off of Europe are warming. off course, the Equator in the Pacific is controlling to a large extent.There it is warming East of 120W which does not count in the U.S. for assessing ENSO. Between 170W and 120W there is some cooling. It is pretty minor and thus explains why NOAA is reporting marginal La Nina ONI values but recognizes that we are in ENSO Neutral nevertheless.  Remember we are talking about changes in the anomalies something like a second derivative so you have to refer to the graphic above this one to know if blue is cool or less warm and if red is warm or less cool.  

Look at the Western Pacific in Motion.`

Western Pacific Tropical Activity

The above graphic which I believe covers the area from the Dateline west to 100E and from the Equator north to 45N `normally shows the movement of tropical storms towards Asia in the lower latitudes (Trade Winds) and the return of storms towards CONUS in the mid-latitudes (Prevailing Westerlies). This is recent data in motion (last 24 hours) not a forecast. But it provides a pretty good idea of what is heading towards Southeast Asia and the Maritime Continent.
The MJO has had significant impacts this prior winter during the development of the El Nino but the impact on this September is not likely to be very noticeable other than alternatively accelerating and decelerating the development of the La Nina. It is forecast to be more significant in October. The forecasts of the MJO are all over the place and not suggesting a strong Active or Inactive Phase of the MJO any time soon. Thus it may be October or November before it really is able to be factored in.

Below is an analysis of projected tropical hazards and benefits over an approximately two-week period. This graphic is scheduled to update on Tuesday and I am reading the September 6, 2016 Version and looking at Week 2 of that forecast.
Tropical Hazards

Mostly for the period September 14, 2016 to Sept 20, 2016, I see a potential cool area impacting Southwest Australia and continued risk of tropical disturbances off the West Coast of Central America but further south than recently. There are wet and dry anomalies that are near other areas but only impacting a small part of those mostly island chains.
Usually I do not report on the first week of the analysis as it has pretty much occurred by the time I go to press.  But I do note the cool anomaly indicated for Uruguay.
I publish late Monday and this graphic updates late Tuesday. I could go back into my article and update the above discussion but I think that readers can interpret this graphic on their own as the Legend is very easy to understand.

Forecast from Japan

Aug. 17, 2016 Prediction from 1st Aug., 2016

ENSO forecast:

The SINTEX-F model initialized with the SST condition observed on July 31st predicts a weak La Niña/La Niña Modoki state in coming months.  [Editor's Note: This article is already running too long so we will not discuss La Nina Modoki tonight but here is a good article to read for those with an interest in the topic]. Although the NCEP GODAS shows an anomalously cold subsurface condition almost all the way from central Pacific to eastern Pacific along the equator in July, the prediction has not picked the strong La Niña/La Niña Modoki signal yet. This might be a model bias due to the simple SST data assimilation scheme used in the initialization. However, we have noted similar prediction results in several other climate models.

Indian Ocean forecast:

As predicted earlier, the negative Indian Ocean Dipole (IOD) has actually emerged in the June-July SST anomalies of the NCEP GODAS data. The model continues predicting the negative IOD for the boreal fall; this will bring a wetter-than-normal (drier-than-normal) condition over the eastern (western) side of the Indian Ocean. There is high possibility of floods in the region near Sumatra and Java, and drought in East Africa. The negative IOD seems to have brought temporary relief to a hot summer over East Japan normally expected in an evolving La Niña year.

Regional forecast:

In boreal fall, as a seasonally averaged view, most part of the globe will experience a warmer-than-normal condition, while northern Brazil will experience a colder-than-normal condition.

According to the seasonally averaged rainfall prediction, U.S., Korea, eastern China, Indo-China and East Africa will experience a drier condition during boreal fall, while most parts of Indonesia and northwestern South America (including Colombia, Ecuador, and western Brazil) will experience a wetter-than-normal condition; this may be mostly due to the negative IOD and the evolving weak La Niña. Also, because of those climate conditions in Indian and Pacific Oceans, Australia is expected to receive above normal rainfall during austral spring and summer. The active South Pacific Convergence Zone (SPCZ) may play a role in this, too However, we expect a weak dry condition in the southwestern coastal region of Western Australia because of the evolution of weak Ningaloo Niña. [ Editor's Note: Click for Explanation and even more detail on the Ningaloo Niña]

Most part of Japan will experience above normal temperature from summer through winter. We expect above normal precipitation in most part of Japan in September-October. However, it may be noted that the forecast skills in those mid- and high-latitudes on regional scales are still limited.+

C. Progress of the Cool ENSO Event

A major driver of weather is Surface Ocean Temperatures. Evaporation only occurs from the Surface of Water. So we are very interested in the temperatures of water especially when these temperatures deviate from seasonal norms thus creating an anomaly. The distribution of the anomalies is very important.
To a substantial extent the temperature anomalies along the Equator have disproportionate impact on weather so we study them intensely and that is what the ENSO (El Nino - Southern Oscillation) cycle is all about
Subsurface water can be thought of as the future surface temperatures. They may have only indirect impacts on current weather but they have major impacts on future weather by changing the temperature of the water surface.
Winds and Convection (evaporation forming clouds) is weather and is a result of the Phases of ENSO and also a feedback loop that perpetuates the current Phase of ENSO or changes it. That is why we monitor winds and convection along or near the Equator especially the Equator in the Eastern Pacific. 

Starting with Surface Conditions.

TAO/TRITON GRAPHIC (a good way of viewing data related to the part of the Equator and the waters close to the Equator in the Eastern Pacific  where we monitor to determining the current phase of ENSO.

I have deleted many of the TAO/TRITON graphics we looked at when we were watching El Nino develop and decline. But I saved this one which was close to the maximum. It was not the maximum but it was the one that I froze which was the closest to the maximum that I saved. It is useful for comparing the current situation with the pattern that prevailed near the peak of the El Nino this past winter. Since most of my graphics auto-update to be able to view a prior version of a particular graphic, I "freeze it" by basically cut and paste to a graphics file and then embed that "frozen graphic" in my article.

January 19, 2016 Frozen TAU/TRITON Graphic

And here is the current version of the TAO/TRITON Graphic.

The above should be compared to the bottom part of the following graphic. Notice the pattern is remarkably similar. The difference is that in January the anomaly was a warm anomaly stretching from 130W to 160W and now it is a cool anomaly. When it was a warm anomaly it was a 3C anomaly in the center ring. Now the center ring is a -1C anomaly. So this is opposite to last winter but the intensity is a third or less of the situation last winter.

Current SST and wind anomalies

Location Bar for Nino 3.4 Area Above and Below
------------------------------------------------  A       B       C      D       E       -----------------

 

The below table which only looks at the Equator shows the extent of anomalies along the Equator. I had split the table to show warm, neutral, and cool anomalies. The top rows showed El Nino anomalies. When there were no more El Nino anomalies along the Equator, I eliminated those rows. The two rows just below that break point contribute to ENSO Neutral and after another break the rows are associated with La Nina conditions. I have changed the reference date to May 23, 1016.

Comparing Now to May 23, 2016

Subareas of the Anomaly

Westward Extension Eastward Extension Degrees of Coverage

As of Today

May 23, 2016

As of Today

May 23 2016

As of Today

In Nino 3.4

May 23, 2016

These Rows Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly*

175E

155E

Land

155W

90

50

50
0C or cooler Anomaly

Dateline

155W

Land

Land

85

50

60
These Rows Show the Extent of the La Nina Impacts on the Equator
-0.5C or cooler Anomaly

170W

145W

120W

Land

50

50

55
-1C or cooler Anomaly

150W

140W

125W

105W

25

25

35
-1.5C or cooler Anomaly

LAND

135W

LAND

120W

0

0

0

 

If you just look on the Equator, there are 50 degrees of Longitude of Neutral to La Nina anomalies which is the maximum possible as the ONI Measurement Area is 50 degrees of Longitude wide and that also is the maximum possible since the ENSO Measurement Area only stretches for 50 degrees. There are 50 degrees of water anomalies cool enough to be a La Nina. Subtracting 50 degrees from the 50 degrees you end up with 0 degrees of ENSO Neutral and 50 degrees of water cool enough to qualify as La Nina i.e. temperature anomalies more negative than -0.5C. This at first glance looks to be more La Nina-ish than last week. But there is zero water along the Equator in the ONI Measurement that is -1.5C or less which would be cool enough to be a  strong La Nina when just looking at the Equator. And this week there is only 25 degrees of water cooler than -1C which is down from last week. But the ONI Measurement Area extends 5 degrees of Latitude North and South of the Equator so the above table is just a guide and a way of tracking the changes. Away from the Equator it is generally warmer when a La Nina is trying to get started. The water from 3N to 5N and from 3S to 5S had until recently remained relatively warm especially west of 150W. But now the warm area has shifted to being east of 135W especially south of the Equator. It is east of the NINO3.4 Measurement Area but is indicative of the weakness of this Cool Event. That is why I describe this as a "Luke Cool" Event.

I calculate the current value of the ONI index (really the value of NINO 3.4 as the ONI is not reported as a daily value) 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 September 12, in the afternoon working from the September 11 TAO/TRITON report, this is what I calculated.

Calculation of ONI from TAO/TRITON Graphic
Anomaly Segment Estimated Anomaly
  Last Week This Week
A. 170W to 160W -0.3 -0.2
B. 160W to 150W -0.6 -0.6
C. 150W to 140W -0.5 -1.0
D. 140W to 130W -0.6 -0.8
E. 130W to 120W -0.5 -0.5
Total -2.5 -3.1
Total divided by five subregions i.e. the ONI (-2.5)/5 = -05 (-3.1)/5=-0.6

 

My estimate of the daily Nino 3.4 ONI has declined to -0.6 which is now a  La Nina value.  NOAA has reported the weekly ONI to be again -0.7 which is a La Nina value.
All the reported values by NOAA this week are the same as last week. They must have known that the theme of my article this week would be "Frozen in Time". How did they know that?
But I question the accuracy of their calculation. It is entirely possible that the TAO/TRITON system is not reporting accurately or that I have made an error in my estimation of the value for Nino 3.4 from the TAO/TRITON graphic. The difference between -0.6 and -0.7 is not substantial this week.
Nino 4.0 is reported as being the same as last week at and the week before at  -0.1.  Nino 3 is being reported as unchanged at -0.3  Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is being reported unchanged at +0.3.  ACCORDING TO NOAA WE REMAIN IN ENSO Neutral BUT WE HAVE HAD OUR ninth straight LA NINA value of Nino 3.4 reported in the NOAA WEEKLY REPORT.  The Australian Bureau of Meteorology two weeks ago announced that their estimate of the value for NINO 3.4 for August was -0.4. IT IS THE SAME OCEAN. They are forecasting that the value for NINO 3.4 will decline to about-0.6 for September.  I believe my rough estimation approach is providing a more realistic ONI value right now than NOAA. There may also be a cyclical variation in the Nino 3.4 reading which impacts what you get based on what day you calculate it but I think these -0.7 values are biased low (more extreme) by about 0.1C. 
Nine weeks are not definitive (the NOAA criteria for declaring an El Nino or La Nina includes five overlapping three-month periods with the appropriate conditions) especially without confirmation from the SOI which we may have now finally. These index measurements are not definitive but they suggest the direction things are headed but other information strongly suggests the ONI readings will soon (NOAA) or after September (Australia BOM) be less negative than they are this week. I am only showing the currently issued version of the NINO SST Index Table as the prior values are shown in the small graphics on the right with this graphic. The same data in graphical form but going back a couple of more years can be found here.  NINO 1+ 2 stubbornly remains positive and determines the weather of Ecuador and Peru.

September 12, 2016 Nino Readings

Sea Surface Temperature and Anomalies

It is the ocean surface that interacts with the atmosphere and causes convection and also the warming and cooling of the atmosphere. So we are interested in the actual ocean surface temperatures and the departure from seasonal normal temperatures which is called "departures" or "anomalies". Since warm water facilitates evaporation which results in cloud convection, the pattern of SST anomalies suggests how the weather pattern east of the anomalies will be different than normal.

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. This Hovmoeller provides a good way to visually see the evolution of this ENSO event.  I have decided to use the prettied up version that comes out on Mondays rather that the version that autoupdates daily because the SST Depatures on the Equator do not change rapidly and the prettied up version is so much easier to read.

September 12, 2016 SST Surface Anomalies

You read this Hovmoeller from bottom to top and you can clearly see how the El Nino ended and we are flirting with La Nina. But you can see the yellow color just west of 120W which suggests the embryonic La Nina is weakening or becoming a Modoki. You can also see how the cool anomaly is drifting west. You can also see the little blue blip just to the west of 120W which combined with the widening of the coolest area from 160W to 140W which is responsible for the slightly lower Nino 3.4 reports from NOAA. Compare this blue pattern to the red pattern higher up which is the prior El Nino. There is no comparison in terms of that was and this may be. You can also see a mini potential El Nino off to the west. It is not where an El Nino is measured. So we need to watch not only the intensity of these warm and cool anomalies but where they are located. This of course drives the computer models crazy. 

Let us look at the Subsurface Water Temperatures.

Equatorial Subsurface Analysis

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.

Current Sub-Surface Conditions.   Notice the lag in getting this information posted so the current situation may be a bit different than shown.

And now the pair of graphics that I regularly provide and which as I publish are currently able to be accessed from the NOAA website. There was a period of time when that website was up and down but it appears to be functioning well recently.

Subsurface Heat Anomalies

The above pair of graphics 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 shows surface temperature anomalies. The coolest water at the surface shows up only in small isolated areas.  Water of La Nina coolness but not very intense shows up along the Equator from 170W to the Coast of Ecuador. But there are pockets of water slightly warmer than -0.5C mixed in including some warm water near 110W. The -1C water shows between 170W and 150W and that is a slightly smaller area than last week. But there is a large gap between 150W and 120W although that gap does not show up on the TAO/TRITON Graphic. The gap, if valid, suggests the possibility that this will evolve into a cool Modoki pattern. The eastern part of the cool water pool is increasingly unimpressive. Notice that below 50 meters, there is no water with a cool anomaly in excess of -2C. How is this cool event to be sustained?

The bottom half of the graphic (Absolute Values which highlights the Thermocline) is now more useful as we track the progress of this new Cool Event.

It shows the thermocline between warm and cool water. The 28C Isotherm is now located at 175W which is about the same as last week.This graphic does not show a 27.5C anomaly which might more precisely indicate where convection is likely to occur. The 27C isotherm is now at 170W so we do not have ideal conditions for significant convection along the Equator east of the Dateline. The 25C isotherm is at about 140 which is less La Nina-ish than last week. The 20C Isotherm has moved close to the surface but is not reaching the surface.  But the amount of warm water just west of the Dateline is also not real impressive either but growing but staying fairly far east. It is clearly a transition state and all of this is important not just for tracking this cool event but thinking about when the next El Nino might be triggered. This graphic helps understand the logic behind some of the forecasts of the ONI. For the past two months we pretty much have had weak La Nina conditions both in terms of water temperatures and the SOI but it appears to be transitory in the sense of the SST's moving more towards La Nina this week with the SOI also flashing La Nina. So it is still a battle going on with La Nina nudging ahead but not looking like it can sustain itself.  .

Here are the above graphics as a time sequence animation. You may have to click on them to get the animation going.

Equatorial Temperature Simulation

Isotherm Simulation

Although I did not discuss the Kelvin Waves earlier, now seems to be the best place to show the evolution of the subsurface temperatures which remains relevant. What we have is only the upwelling phase of the series of Kelvin waves last winter.

September 12, 2016 Subsurface Temperatures.

There is cool water from 170W to the coast of Ecuador. But the coolest water, however, is only reaching the surface from 168W to 150W which is again a smaller area than recently. There is also a huge gap in the coolest water between 150W all the way to LAND with a warm anomaly at about 108W. There were initial signs that this might evolve into a weak La Nina Modoki. It is very interesting that the western part of the surface and subsurface has more extreme cool anomalies than further east. The eastern part of the cool anomaly is far less impressive than the western part. There is no comparison. The eastern part of the anomaly is not factored into the measurement of the ONI but it impacts weather in Ecuador and Peru. The western part is plenty potent but is not being reinforced by more cool water arriving from the west. So it is simply a matter of the cooler subsurface water mixing out. So this cool event would appear to be self-limiting. It actually looks like we have three distinct areas of cool water. All three I think are drifting west.

And now Let us look at the Atmosphere.

Low-Level Wind Anomalies near the Equator

Here are the low-level wind anomalies.

Low Level Wlind Anomalies

There are mostly westerly anomalies east of 160W probably related to the MJO and destroying the budding La Nina. .

And now the Outgoing Longwave Radiation Anomalies which tells us where convection has been taking place. 

OLR Anomalies Along the Equator

In the above graphic, we see basically no convection along the Equator other than west of the Dateline. It s a cool event pattern but not very impressive.

And Now the Air Pressure which Shows up Mostly in an Index called the SOI.

This index provides an easy way to assess the location of and the relative strength of the Convection (Low Pressure) and the Subsidence (High Pressure) near the Equator. Experience shows that a comparison between Air Pressure at Tahiti and Darwin Australia is substantially correlated with the Precipitation Pattern of the entire World.. 

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.

Date Current Reading 30-Day Average 90 Day Average
Sept 6    -0.83 +7.13 +5.29
Sept 7    -1.07 +7.08 +5.07
Sept 8   +7.13 +7.01 +4.95
Sept 9 +10.88 +7.00 +4.90
Sept 10 +13.31 +7.19 +5.05
Sept 11 +12.36 +7.55 +5.20
Sept 12 +18.25 +8.21 +5.36

 

The 30-day average, which is the most widely used measure, as of September 12 is reported at +8.21 which is up fairly considerably from last week and is a La Nina level. The 90-day average at +5.36 is essentially unchanged from last week and is again borderline but clearly trending towards La Nina. These may be the high water marks for the SOI re this cycle. Usually but not always the 90 day average changes more slowly than the 30 day average but it depends on what values drop out. The disparity between the two is one reason why we look at both. Different agencies use a different range to classify the SOI as being El Nino or La Nina. The tightest range (I have referred to that as "strictest" but that may not be a clear way of putting it)  is -5 for El Nino and +5 for La Nina. Some meteorological agencies sometimes use -8 or +8. So the range +5 to -5 is clearly neutral and above +8 is clearly La Nina and below -8 is clearly El Nino and between -8 and -5 and +5 to + 8 is somewhat marginal but suggestive of El Nino if negative and La Nina if positive. For many purposes the trend is more important than the absolute level. So clearly the Upper Atmosphere has a slight trend right now towards La Nina.

The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource. August has not been particularly favorable for La Nina development and neither will be September in terms of the MJO. The MJO being Inactive is more favorable for La Nina than the MJO being Active. It is complicated in that some models predict a strong active MJO for September which normally means westerlies which is negative for the development of the La Nina. But the MJO goes back and forth from being Active, Inactive, strong and weak so in has mostly a short-term impact. Right now the impact is fairly muted. It tends to be more important when the situation is ENSO Neutral and the MJO can start the process of an El Nino getting started. It is less significant re the initiation of a La Nina but is a factor. It is surprising how weak the MJO has been for months.

Forecasting the Evolution of ENSO

The below is  (Mid-Month) Model- Based forecast issued on August 18, 2016 followed by Early Month Consensus-Based forecast issued on September 8, 2016.  It is important to remember that the first report in each month is based on a survey of meteorologists and the second report later in the month is based on the analysis of the forecast models. It is a minor difference but a difference.

First the Model-Based Forecast published on August 18, 2016.

August 18, 2016, IRI-CPC Model-Based ENSO Analysis

And now the Early September "Probabilistic Forecast which includes a large component of input from meteorologists as compared to the second forecast in the month which is more tied to model results without interpretation. It is not a big difference but it is a difference. I assume they do it this way as to avoid forcing meteorologists to have to run their computers twice a month (some sarcasm expressed there).

September 8, 2016 CPC/IRI Official Probabilistic Forecast.

Notice that with this release, the probabilities for La Nina have changed dramatically since the August 18 analysis with Neutral being the most likely Phase of ENSO and the next El Nino beginning to show up on the meteorologist's radar. 

We have suggested that it is possible that some of the models and in particular NOAA's model will be wrong about how fast the Eastern Pacific Warm Pool moves back towards its La Nina location and it may well be that next winter will be more of a Neutral year or even have some characteristics of an El Nino Modoki and thus be wetter than a typical year as the Warm Pool may still be more in the Central Pacific than shifted all the way west to its La Nina position.

 CFS.V2 SST Forecast

The mean of the NOAA model was until recently forecasting a fairly strong La Nina for next winter. The model gradually shifted to a weak La Nina Forecast and now to a marginal La Nina Forecast. Is the Mean of the forecast ensemble for the key periods NDJ and DJF below -0.5?  For two weeks it looked like it no longer seemed to be but now suddenly it does albeit barely. You can see the same thing in the Australian POAMA model and the August 1 JAMSTEC model run. The mean of the model ensemble for the ONI in the NOAA model has turned higher (less La Nina-ish actually on the El Nino side of Neutral) for the Spring of the coming winter as you can see. The last few days the more recent runs have been a bit more La Nina-ish especially for early next year. So right now this is forecast to be a short La Nina if it indeed actually meets the criteria to be recorded as a La Nina which remains to be seen. I doubt that this cool event will be recorded as a La Nina since it most likely will not  meet the criteria for being classified as a La Nina.  But it is forecasted to be close enough that whether it officially is logged in as a La Nina or Neutral, probably has very little impact on the weather we will have.

The full list of weekly values can be found here.

Forecasts from Other Meteorological Agencies.

View from Australia

El Nino

Australia POAMA ENSO model run

Below is the discussion just released. Notice the discussion re forecasting a La Nina for next winter. POAMA is not currently predicting a La Nina. POAMA is the Australian Bureau of Meteorology (BOM) proprietary forecasting model. BOM also consults the other international forecasting models and after that consultation is not forecasting a La Nina at this point in time as per below. Notice they use a different standard than NOAA namely + or - 0.8 rather than the + - 0.5 that NOAA sues. But even with the NOAA Standard, POAMA would not be forecasting a La Nina. BOM is reporting a value of NINO 3.4 of -0.4 while NOAA reports it at -0.7. How that can be is a mystery. And with NOAA criteria,  the duration must be five overlapping three month periods which is about the same as seven months but with some leeway to not meet the criteria for a particular month.

Outlooks from the eight international climate models surveyed by the Bureau have eased back slightly in terms of the chance of La Niña, compared to two weeks ago. However, many of the models continue to show borderline cool conditions to be likely and most models include ensemble members which exceed La Niña thresholds. Overall, only one of the surveyed models indicates a clear La Niña is likely to develop and persist across the outlook period.

If La Niña does form, models suggest it will be weak, potentially short-lived, and well below the strength of the significant 2010–12 event.

During La Niña, northern and eastern Australia typically experience above average spring rainfall, with the first rains of the wet season typically arriving earlier than average in northern Australia. At present, warmer than average seas surrounding Australia—which more typically occur during La Niña—mean some La Niña–like impacts may occur even if thresholds are not exceeded.

IOD (Indian Ocean Dipole)

IOD POAMA Model Run

The graphic comes with discussion that is usually very short but longer tonight for obvious reasons, Here is that discussion:

The negative Indian Ocean Dipole (IOD) event continues, and has strengthened compared to two weeks ago as areas of cool anomalies have re-emerged in the western Indian Ocean adjacent to the coastline of Africa. Warm anomalies in the eastern Indian Ocean, between northwestern Australia and Indonesia, have also strengthened compared to two weeks ago. The weekly index value to 11 September was −1.19 °C.

The Indian Ocean Dipole (IOD) index has been below the −0.4 °C negative IOD threshold for sixteen weeks, peaking at −1.37 °C in early July. The July 2016 monthly IOD index value reported in the ERSSTv4 dataset was the strongest negative value in at least 50 years of record. 

International climate models indicate the negative IOD will steadily weaken during spring, as is typical of the lifecycle of IOD events. This means its influence on Australian rainfall may lessen in the coming months.

A negative IOD typically brings above average rainfall to eastern Australia during spring, cooler than normal daytime temperatures to southern Australia, and warmer daytime and night-time temperatures to northern Australia.

Information on the impact of a negative IOD on Australia can be found here

We have the JAMSTEC August 1 ENSO forecast and are waiting for the updated forescast which should be very soon.

The model shows ENSO Neutral for the next two years..The discussion below the graphic is far more nuanced. It has not changed since last issued but it is informative so I am repeating it.

Aug. 17, 2016 Prediction from 1st Aug., 2016

ENSO forecast:

The SINTEX-F model initialized with the SST condition observed on July 31st predicts a weak La Niña/La Niña Modoki state in coming months.  [Editor's Note: This article is already running too long so we will not discuss La Nina Modoki tonight but here is a good article to read for those with an interest in the topic]. Although the NCEP GODAS shows an anomalously cold subsurface condition almost all the way from central Pacific to eastern Pacific along the equator in July, the prediction has not picked the strong La Niña/La Niña Modoki signal yet. This might be a model bias due to the simple SST data assimilation scheme used in the initialization. However, we have noted similar prediction results in several other climate models.

Indian Ocean forecast:

As predicted earlier, the negative Indian Ocean Dipole (IOD) has actually emerged in the June-July SST anomalies of the NCEP GODAS data. The model continues predicting the negative IOD for the boreal fall; this will bring a wetter-than-normal (drier-than-normal) condition over the eastern (western) side of the Indian Ocean. There is high possibility of floods in the region near Sumatra and Java, and drought in East Africa. The negative IOD seems to have brought temporary relief to a hot summer over East Japan normally expected in an evolving La Niña year.

Regional forecast:

In boreal fall, as a seasonally averaged view, most part of the globe will experience a warmer-than-normal condition, while northern Brazil will experience a colder-than-normal condition.

According to the seasonally averaged rainfall prediction, U.S., Korea, eastern China, Indo-China and East Africa will experience a drier condition during boreal fall, while most parts of Indonesia and northwestern South America (including Colombia, Ecuador, and western Brazil) will experience a wetter-than-normal condition; this may be mostly due to the negative IOD and the evolving weak La Niña. Also, because of those climate conditions in Indian and Pacific Oceans, Australia is expected to receive above normal rainfall during austral spring and summer. The active South Pacific Convergence Zone (SPCZ) may play a role in this, too However, we expect a weak dry condition in the southwestern coastal region of Western Australia because of the evolution of weak Ningaloo Niña. [ Editor's Note: Click for Explanation and even more detail on the Ningaloo Niña]

Most part of Japan will experience above normal temperature from summer through winter. We expect above normal precipitation in most part of Japan in September-October. However, it may be noted that the forecast skills in those mid- and high-latitudes on regional scales are still limited.

D. Putting it all Together.

Last winter's El Nino has officially ended in terms of currently satisfying the criteria. We are now speculating on the winter of 2016/2017 which now according to some of the models seems likely to be a La Nina or Neutral with a La Nina bias. But Australia and Japan do not see it that way and are not calling for a La Nina at this point in time. So NOAA is a bit the Odd Man Out but it is mostly a question of degree. NOAA is calling for a borderline La Nina and the others are forecasting a La Nina-ish event that does not quite meet the criteria for being labeled a La Nina and does not last long enough to meet the criteria.

Forecasting Beyond Five Years.

So in terms of long-term forecasting,  none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast. The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.   It includes decade by decade predictions through 2050. Predicting a particular year is far harder.

The odds of a climate shift for CONUS taking place has significantly increased. It may be in progress. It looks like it will require one more La Nina or ENSO Neutral event and this appears to be the way this might unfold. The AMO is pretty much neutral at this point so it may need to become a bit more negative for the McCabe A pattern to become established. That seems to be slow to happen so I am thinking we need at least a couple more years for that to happen..maybe as many as five.

E. Relevant Recent Articles and Reports

Weather in the News

Newton takes a toll

Weather Research in the News

Peak Hurricane

Global Warming in the News

Impact of carbon dioxide increases on grasslands may be more complex than first thought.  Full Paper

F. TABLE OF CONTENTS FOR PAGE II OF THIS REPORT WHICH PROVIDES A LOT OF BACKGROUND INFORMATION ON WEATHER AND CLIMATE SCIENCE  

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.

1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)

2. Medium Frequency Cycles such as ENSO and IOD

3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.

4. Computer Models and Methodologies

5. Reserved for a Future Topic  (Possibly Predictable Economic Impacts)

G. TABLE OF CONTENTS FOR PAGE 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.

1. Introduction

2. Climate Impacts of Global Warming

3. Economic Impacts of Global Warming

4. Reports from Around the World on Impacts of Global Warming

Useful Background Information

With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not as easily interpreted. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.

  El Ninos La Ninas
  Start Finish Max ONI PDO AMO Start Finish Max ONI PDO AMO
            DJF 1950 J FM 1951 -1.4 - N
T   JJA 1951  DJF 1952 0.9 - +          
   DJF 1953  DJF 1954 0.8 - + AMJ 1954  AMJ 1956 -1.6 - +
M MAM 1957   JJA 1958 1.7 + -          
M SON 1958  JFM 1959 0.6 + -          
M   JJA 1963  JFM 1964 1.2 - - AMJ 1964  DJF 1965 -0.8 - -
M  MJJ 1965 MAM 1966 1.8 - - NDJ 1967 MAM 1968 -0.8 - -
M OND 1968   MJJ 1969 1.0 - -          
T  JAS 1969   DJF 1970 0.8 N -  JJA 1970  DJF 1972 -1.3 - -
T AMJ 1972  FMA 1973 2.0 - - MJJ 1973 JJA 1974 -1.9 - -
            SON 1974 FMA 1976 -1.6 - -
T ASO 1976  JFM 1977 0.8 + -          
M ASO 1977

 DJF  1978

0.8 N -          
M SON 1979  JFM 1980 0.6 + -          
T MAM 1982  MJJ  1983 2.1 + - SON 1984 MJJ 1985 -1.1 + -
M ASO 1986  JFM 1988 1.6 + - AMJ 1988 AMJ 1989 -1.8 - -
M MJJ 1991     JJA 1992 1.6 + -          
M SON 1994   FMA 1995 1.0 - - JAS 1995 FMA 1996 -1.0 + +
T AMJ 1997   AMJ 1998 2.3 + + JJA 1998 FMA 2001 -1.6 - +
M MJJ 2002   JFM 2003 1.3 + N          
M  JJA 2004 MAM 2005 0.7 + +          
T ASO 2006   DJF 2007 1.0 - + JAS 2007  MJJ 2008 -1.4 - +
M JJA 2009 MAM 2010 1.3 N + JJA 2010 MAM 2011 -1.4 + +
            JAS 2011 FMA 2012 -0.9 - +
T MAM 2015 NA 1.0 + N          

 

ONI Recent History

ONI History Updated on September 5, 2016

The official reading for Jun/Jul/Aug is now reported as -0.3. As you can see this recent El Nino peaked in NDJ and has now ended and depending on what system you use it is either the 2nd or 3rd strongest El Nino since modern records were kept which is considered to be 1950. You could argue for it being #1 based on a week of readings but few are buying that argument. Still #2 or #3 means it is one of the strongest ever based on the way these events are measured. I will be writing more about that soon in a separate article. I believe the measurement system is inadequate re being useful in forecasting Worldwide weather impacts. The JJA is not a La Nina Value. So there would need for there to be five periods of -0.5 or colder starting with JAS. It is not even clear that JAS will record as -0.5 or less. So the chances of this event being an official La Nina are very low.

The full history of the ONI readings can be found here. The MEI index readings can be found here.

Click here for a list of Sig Silber's Weather Posts

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