This week should be a continuation of last week and then a change in the pattern which will moderate the extreme cold being experienced along the Northern Tier of CONUS is "likely". NOAA continues to pretend we are having a La Nina. In the News Section, I have a link to an NCAR study and the key graphic that attempts to show where the probability of intense precipitation events is likely to occur with high-end projected impacts of Global Warming. It is very interesting.
First I want to provide some context to the word "likely" as used in the paragraph above. It is not that NOAA is unconvinced that there will be a pattern change as much as the exact way it will unfold is proving to be difficult to determine as the models keep changing their analysis and refusing to converge on the forecast.
Now some housekeeping information. Working on a Glossary of Terms but right now it is only partially operational. It will be possible increasingly to look up acronyms etc by going to theGEI Weather Page Glossary. Also for those who want the forecasts beyond three months, we reported previously on the November 17 NOAA 15-Month Forecast and compared the first ten months of the NOAA Outlook with that of JAMSTEC in a special Update that you can get to by clicking here. We will of course publish a new 15 Month Update Report shortly after December 15, 2016. Remember if you leave this page to visit links provided in this article, you can return by hitting your "Back Arrow", usually top left corner of your screen just to the left of the URL box.
A. Focus on Alaska and CONUS (all U.S. except Hawaii) - Let's Focus on the Current (Right Now to 5 Days Out) Weather Situation.
First, this graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.
To turn the above into a forecasting tool click here and you will have a dashboard for a short-term forecasting model.
Notice that right now the major moisture inflow is mostly from two sources that impact the Southeast and East Coast. The Pacific entry point is controlled by the Aleutian Low and the northerly displaced RRR. (North Pacific High) .
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 links provided below.
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
Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 3. The Day 6 forecast can be found here.
The Aleutian Low is a non-split Low with central air pressure of perhaps 956 hPa (it is so tightly wound I can't really tell) and is centered over Kamchatka. The average sea level air pressure in the winter is 1001 hPa and 994 hPa for a non-split Low. This graphic changes every six hours.
The High Pressure off of California, the familiar RRR, is back with Central Pressure of 1032 hPa. Thus, right now the RRR (Ridiculously Resilient Ridge) is again doing its job of protecting the West Coast from Pacific storms and also providing northerly winds for California. But it is very far north. The forecast is for storms entering the States of Oregon and Washington. How that happens is not totally clear but we will find out.
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 3. It is not the current situation but Day 3 is not very far out.
Here is the seven-day precipitation forecast. More information is available here.
That is a lot of moisture expected in the Northwest and Eastern half of CONUS.
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. Remember that 540 relates to sea level.
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 in the above graphic is a strong Positively Oriented (Northeast to Southwest) Western Trough with Ridges (high pressure) to the East and West. The exact evolution of this trough is being fiercely debated by the various weather forecasting models. Remember this is a forecast for Day 7. Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. The 540 line on Day 7 barely intrudes into CONUS. But we observe that the Media have been over-exuberant in reporting the cold snap. Meteorological Winter began on December 1.
The graphic below is the Eastern Pacific a 24 hr loop of recent readings. It does a good job of showing what is going on right now. When I published, this graphic was not being displayed but the website indicated that was a temporary outage.
The winds and moisture approaching the West are of most interest. You can clearly see the split flow of the Jet Stream and the flows into California which is not currently blocked by the RRR and the subtropical flow through Mexico but which this week is not significantly impacting CONUS. .
The graphic below (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 tropical weather patterns unlike the patterns north of 30N are generally moving from east to west but right now are moving from west to east. This graphic highlights tropical activity. Unlike the above which shows recent history, the below graphic is a satellite image with the forecast of tropical events superimposed on the satellite image. There is no significant "new" tropical activity that would appear to impact CONUS forecast for the beginning of this week.
Below is the current water vapor Imagery for North America.
Tonight, Monday evening December 12, 2016 (and this is the current situation not an animation of recent history), as I am looking at the above graphic, we see mostly continued zonal flow.
Looking at the current activity of the Jet Stream.
First the current situation. 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. The sub-Jetstream level intensity winds shown by the vectors in this graphic are also very important in understanding the impacts north and south of the Jet Stream which is the higher-speed part of the wind circulation and is shown in gray on this map. 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. This usually is more significant for the lower half of CONUS i.e. further south than the Jet Stream.
One sees the current jet stream above. Notice the wind speeds are fairly low perhaps due to the Inactive Phase of the MJO.
Now looking at the 5 Day Forecast
You can see the Zonal Flow becoming more of a split flow. That is an impressively wide jet stream. Notice the wind speeds are much stronger. Also the pattern is more complicated and also notice the sharp turn to the north east of CONUS but which may impact parts of Canada. It is reflecting the forecasted trough. The actual details of this situation will determine the sensible (observed at ground level) impact. This is the forecast of one model 5 days out. So a lot can happen between now and then.
Putting the Jet Stream into Motion and Looking Forward a Few Days Also
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.
When we discuss the jet stream and for other reasons, we often discuss different layers of the atmosphere. These are expressed in terms of the atmospheric pressure above that layer. It is kind of counter-intuitive to me. The below table may help the reader translate air pressure to the usual altitude and temperature one might expect at that level of air pressure. It is just an approximation but useful.
Re the above, H8 is a frequently used abbreviation for 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.
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. It could be included in the Worldwide weather forecast section of this report but it is useful here re understanding the wind circulation patterns.
Four- Week Outlook
I am going to show the three-month DJF Outlook (for reference purposes although I do not have a lot of confidence in it), the Updated Outlook for the single month of December, the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 - 4 Experimental Outlook. I use "EC" in my discussions although NOAA sometimes uses "EC" (Equal Chances) and sometimes uses "N" (Normal) to pretty much indicate the same thing although "N" may be more definitive.
First - Temperature
Here is the Three-Month DJF Temperature Outlook issued on November 17, 2016:
Here is the Temperature Outlook for December Issued on November 30, 2016
6 - 10 Day Temperature Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
8 - 14 Day Temperature Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
Looking further out.
As I view these maps on Monday December 12 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday, it appears that the pattern during December 18 to January 6 will start with Alaska EC and then turning cool and a warm anomaly in the Southeast. The major feature is a fairly cool Northern Tier that extends in the West further south but with declining intensity. This then changes rapidly with the northern cool anomaly retrograding west and the southeast warm anomaly extending to the north and wrapping around to include part of the Northern Tier extending beyond Minnesota. Elsewhere it is EC. The pattern then morphs into a pattern that has a cool Alaska including the Alaska Panhandle and the Northwest, a small cool North Central anomaly and a warm Southern Tier that in the East extends north through Pennsylvania and New Jersey. We had a concern last week that the sequence indicated might not work out if the cool anomaly was not able to clear the East Coast in time. We had not foreseen that the cool anomaly would in the forecast retrograde west. To be "warm" with respect to anomalies means warmer than usual for this time of year and "cool" with respect to anomalies means cooler than usual for this time of the year. The graphic shows the level of probability of being different from EC.
Now - Precipitation
Here is the three-month DJF Precipitation Outlook issued on November 17, 2016 that I do not have much confidence in.
Mea Culpa for some weeks now the Temperature forecast was shown above rather than the Precipitation Forecast. It is corrected now but I can not go back and correct prior issues and it is not important enough to ask my Editor to do that for me. .
And here is the Updated Precipitation Outlook for December Issued on November 30, 2016
6 - 10 Day Precipitation Outlook Issued Today(Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
8 - 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
Looking further out.
As I view these maps on Monday December 12 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday, it looks like precipitation for December 18 to January 6 will begin with Alaska wet then turning mostly EC cool with parts of the Southwest dry with the dry anomaly initially extending north to the border with Canada encompassing the Rocky Mountain States and most of the rest of CONUS wet. Gradually the mid-latitude Rocky Mountain States also become wet, The pattern would then morph into one with Alaska and the Southern Tier dry (but not extending very far north) and a small part of the Northwest and an area stretching from Tennessee to New Jersey wet. The transition between December 20 - 26 and the December 24 - January 6 maps appears to be fairly abrupt but that does not mean it will not happen that way given the 3 - 4 Experimental Forecast covers a two-weak period. When discussing anomalies, "wet" means wetter than usual for this time of the year and "dry" means drier than usual for this time of the year. The graphic shows the level of probability of being different from EC.
Here is the NOAA discussion released today December 12, 2016.
6-10 DAY OUTLOOK FOR DEC 18 - 22 2016
TODAY'S MODELS EXHIBIT FAIR AGREEMENT ON THE PREDICTED 500-HPA HEIGHT PATTERN. A WEAKENING RIDGE IS PREDICTED NEAR THE ALASKA PANHANDLE. DOWNSTREAM OF THIS RIDGE, A POSITIVELY TILTED TROUGH IS PREDICTED OVER THE WESTERN CONUS. RIDGING AND ABOVE NORMAL HEIGHTS ARE FORECAST FOR THE SOUTHEASTERN CONUS. HEIGHTS ARE FORECAST TO BE BELOW NORMAL FOR MUCH OF THE HIGH LATITUDES CONSISTENT WITH A POSITIVE AO. ENSEMBLE SPREAD IS GENERALLY LOW TO MODERATE, EXCEPT NEAR THE SOUTHWESTERN CONUS AS SOME OF THE GFS AND ECMWF ENSEMBLE MEMBERS PREDICT A CUT-OFF LOW OFF THE COAST OF BAJA CALIFORNIA. THE GREATEST WEIGHT IN TODAY'S MANUAL, 500-HPA HEIGHT BLEND WAS GIVEN TO THE 0Z ECMWF ENSEMBLE MEAN SOLUTION BASED ON CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE PREDICTED PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.
BELOW NORMAL TEMPERATURES ARE FAVORED, PARTICULARLY EARLY IN THE PERIOD, ACROSS THE NORTHERN TIER OF THE CONUS AS WELL AS MUCH OF THE CENTRAL AND WESTERN CONUS UNDERNEATH PREDICTED CYCLONIC FLOW. PREDICTED ABOVE NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR THE SOUTHEASTERN CONUS. ENHANCED PROBABILITIES FOR NEAR NORMAL TEMPERATURES ARE INDICATED FOR MOST OF ALASKA DUE TO AN EXPECTED TRANSITION FROM MILDER THAN NORMAL CONDITIONS EARLY IN THE PERIOD TO COLDER THAN NORMAL TEMPERATURES LATER. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE PANHANDLE IN ASSOCIATION WITH A PREDICTED WEAKENING RIDGE.
THERE ARE ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE EASTERN CONUS AHEAD OF THE TROUGH FORECAST OVER THE CENTRAL AND WESTERN CONUS. PRECIPITATION ESTIMATES FROM THE ECMWF AND GEFS ENSEMBLE MEMBERS AS WELL AS ANALOGS FROM THE MANUAL BLEND FAVOR BELOW MEDIAN PRECIPITATION FOR MUCH OF THE CENTRAL CONUS AND PARTS OF THE SOUTHWEST. AN ENHANCED JET FORECAST OVER THE EASTERN PACIFIC LEADS TO ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE NORTHWESTERN CONUS. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR MUCH OF ALASKA CONSISTENT WITH DYNAMICAL MODEL GUIDANCE FROM THE GEFS AND ECMWF ENSEMBLE MEMBERS.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO A LIKELY PATTERN SHIFT DURING THE OUTLOOK PERIOD.
8-14 DAY OUTLOOK FOR DEC 20 - 26 2016
DURING THE 8-14 DAY PERIOD, MODELS AGREE IN PREDICTING BELOW NORMAL HEIGHTS FOR ALASKA AND MUCH OF THE HIGH LATITUDES. WEAKLY CYCLONIC FLOW IS FORECAST FARTHER TO THE SOUTH OVER MUCH OF THE CONUS. HEIGHTS ARE GENERALLY PREDICTED TO BE BELOW NORMAL OVER THE NORTHWESTERN CONUS. ABOVE NORMAL HEIGHTS ARE PREDICTED ACROSS MUCH OF THE EAST IN ASSOCIATION WITH A RIDGE FORECAST NEAR THE SOUTHEASTERN CONUS. ENSEMBLE SPREAD IS MODERATELY HIGH, PARTICULARLY OVER THE WESTERN CONUS, AND RUN TO RUN CONSISTENCY AMONG THE DETERMINISTIC GFS IS RELATIVELY POOR. DUE TO DISAGREEMENTS AMONG THE DETERMINISTIC RUNS, TODAY'S WEEK-2 MANUAL HEIGHT BLEND IS BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS.
THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF ALASKA UNDERNEATH PREDICTED BELOW NORMAL HEIGHTS. BELOW NORMAL TEMPERATURES ARE ALSO FAVORED FOR MUCH OF THE WESTERN CONUS IN ASSOCIATION WITH FORECAST CYCLONIC FLOW. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN CONUS, PARTICULARLY THE SOUTHEAST, DUE TO PREDICTED RIDGING AND ASSOCIATED ABOVE NORMAL HEIGHTS.
ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE EASTERN CONUS CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS. DYNAMICAL MODEL GUIDANCE FROM THE GEFS AND ECMWF ENSEMBLE MEMBERS SUPPORT ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR THE NORTHERN PLAINS. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE ALEUTIANS IN ASSOCIATION WITH A PREDICTED ENHANCED JET. ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION ARE ALSO INDICATED FOR THE NORTHWESTERN CONUS NORTHWARD TO SOUTHEASTERN ALASKA IN ASSOCIATION WITH PREDICTED ZONAL 500-HPA FLOW. BELOW MEDIAN PRECIPITATION IS FAVORED TO THE SOUTH OF THE ANTICIPATED MEAN STORM TRACK ACROSS PARTS OF THE SOUTHWESTERN CONUS.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO A LIKELY PATTERN SHIFT DURING THE PERIOD AS WELL AS RELATIVELY POOR AGREEMENT AMONG THE FORECAST TOOLS ACROSS PARTS OF THE FORECAST DOMAIN.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON DECEMBER 15
Some might find this analysis interesting as the organization which prepares it focuses on the Pacific Ocean and 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.
Nov 16, 1955
Nov 17, 1955
Dec 18, 1964
Dec 24, 1983
After Powerful El Nino
Dec 25, 1983
After Powerful El Nino
Nov 28, 1995
Dec 21, 1996
Dec 23, 1996
Dec 19, 2008
Dec 20, 2008
(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 November 16 to December 25 which is 39 days which is quite a bit a larger spread than last week. 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 December 5. These analogs are centered on 3 days and 4 days ago (December 7 or December 8). So the analogs could be considered pretty much in sync with the calendar meaning that we will be getting weather that normally would occur at about this time of year or a few days earlier..
There are no El Nino Analogs, four La Nina Analogs and six ENSO Neutral Analogs. The phase of the ocean cycles in the analogs points strongly towards McCabe Condition D. There are some aspects of the 6 - 14 Day Forecast that are consistent with McCabe Condition D. It is a La Nina type Southwest Drought scenario.
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.
Very Little Drought. Southern Tier and Northern Tier from Dakotas East Wet
More wet than dry but Great Plains Dry
Northern Tier and Mid-Atlantic Drought
Southwest Drought extending to the North and also the Great Lakes
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 recently.
Here is the 30 Days ending December 3, 2016
The temperature warm anomalies have moderated. So has the precipitation pattern. Remember only seven days are added and seven more distant days removed so a 30 average with one week changing is designed to react slowly to the change
And the 30 Days ending December 10, 2016
.The precipitation pattern changed around a bit with that wetter North Central Area and South Texas reaching down to Mexico. The temperature pattern moderated except for the Great Lakes and a bit west but that will change next week. Remember this graphic shows the most recent 30 days so 7 days are added and 7 days are dropped so it changes intentionally slowly.
B. Beyond Alaska and CONUS Let's Look at the World which of Course also includes Alaska and CONUS
World Weather Forecast produced by the Australian Bureau of Meteorology. Unfortunately I do not know how to extract the control panel and embed it into my report so that you could use the tool within my report. But if you visit it Click Here you will be able to use the tool to view temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool. Return to this report by using the "Back Arrow" usually found top left corner of your screen to the left o the URL Box. It may require hitting it a few times depending on how deep you are into the BOM tool.
Although I can not display the interactive control panel in my article, I can display any of the graphics it provides so below are the current worldwide precipitation and temperature forecasts for three days out. They will auto-update and be current for Day 3 whenever you view them. If you want the forecast for a different day Click Here
Notice the three strong Northern Hemisphere Lows two of which are in the Atlantic. Remember this is a forecast three days out. You can also see the wet condition in the Western Pacific and into the Indian Ocean.
Notice the Siberian and Northeastern Canada cold and Northern Australian and Sahel heat.
Looking Out a Few Months
This is the new precipitation forecast from Queensland Australia.
But the above is based on October/November having a rapid rise in SOI which was not the case so I used the option where you can change the assumption to a relatively stable SOI and generated a second forecast.
It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. Recently, we ran a weather column with the Title El Nino or La Nina? The point of that article was simply that ENSO is not solid La Nina at this point. We are getting mixed signals. This project may be based on a mixed signal but it also is based on the lag between the SOI and weather impacts so it may be valid even if the SOI begins to increase now.
Here is the most recent JAMSTEC three month Temperature Forecast. (We expect to get an update of this within two weeks.
It is mostly warm but with notable cool areas in Northern Brazil, Australia, and Greenland and Mongolia.
And here is the most recent three month JAMSTEC Precipitation Forecast. We expect to receive an update of this within two weeks.
Of interest is the wet Brazil and dry Maritime Continent and parts of Southeast Asia.
And then to get more focus, I extracted and enlarged an image for Europe on the left and CONUS on the right.
For many purposes 55N latitude is the dividing line in Europe in regards to the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) Impacts. You see that here with Scandinavia wet and southern Europe dry. It is suggestive of AO+. The NAO is highly correlated with the AO so it is also suggestive of NAO +. For CONUS it is a La Nina pattern but different than shown below for NOAA and it is not a North/South divide.
There is a short JAMSTEC discussion that relates the seasonal outlook to their El Nino and El Nino Modoki forecasts and this was issued on Tuesday November 22, so here it is:
Nov. 23, 2016 Prediction from 1st Nov., 2016
According to the SINTEX-F prediction, the current La Niña Modoki/La Niña state will continue until spring. [Editor's Note: They explain what they mean by this being a Modoki rather than a true La Nina in a very long detailed explanation which focuses on the Modoki aspects of this Cool Event. We will discuss that next Monday but the simple explanation is that the cool anomaly is not well connected to the coast of South America]. That state will then start decaying and the tropical Pacific will return to a normal state by summer. The model prediction appears to be consistent so far with the observed evolution of the sea surface temperature (SST) anomalies
Indian Ocean forecast:
The negative Indian Ocean Dipole will keep decaying and disappear in winter. The Ningaloo Nino will appear off the west coast of Australia in late austral summer and persist until late austral fall.
On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of northern Brazil, Australia, and Mongolia will experience a colder-than-normal condition in the boreal winter.
According to the seasonally averaged rainfall prediction, most parts of southern China, southeastern Africa, southern Europe, and eastern/western U.S. will experience a drier condition during boreal winter, while most parts of Brazil, western Central Africa, and South Africa will experience a wetter-than-normal condition. Australia will receive above normal rainfall during austral summer. Northern parts of Japan (including Hokkaido) will be cooler and drier than normal while southern parts of Japan will generally be warmer than normal in winter. However, we note that fluctuating mid- and -high latitude climate in winter may not be captured well by the current model.
Additional forecasts from JAMSTEC including future time periods can be found at this link.
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.
What happened to the presumed La Nina? Did it go into Hibernation? Last Monday we wondered if NOAA had noticed? We received the answer on Thursday December 8. NOAA still believes that La Nina Conditions apply.
Remember this discussion is all about anomalies not absolute temperatures...so it is deviation from seasonal norms.
The waters north and east of Japan remain very cool which means that the waters south of Kamchatka Siberia are also cold, The Central Indian Ocean is now basically IOD Neutral. The waters off the Southern Coast of Australia are cool but the East Coast is slightly warm. Water north of Australia is slightly warm but less so than one would expect with La Nina. The waters southeast of Africa are cool. To the west of Africa especially in the Gulf of Guinea, the water is warm.
The overall Northern Pacific no longer looks to be PDO Positive (the horseshoe pattern with the cool anomaly inside the horseshoe shape there) mostly because of the lack of warm water east and south of the cool water. But the cool anomaly is growing and moving to the east. The NOAA Pacific Decadal Oscillation (PDO) Index as reported by NOAA (Washington University also reports the PDO but using a different methodology which results in higher index numbers) has been 2016-January 0.79, 2016- February 1.23, 2016- March 1.55, 2016- April 1.59. 2016- May 1.40, 2016-June 0.76, 2016-July 0.12, 2016-August-0.90, 2016- September -1.09, 2016- October -0.88. The above would make the PDO now NEGATIVE but may becoming less NEGATIVE. Here is the list of PDO values.
The waters west of CONUS are now neutral probably due to the northerly winds creating upwelling. The Gulf of California is neutral. Further north, the Gulf of Alaska is warm close to land with the Bering Straits also warm.but not overly impressive,
The Black Sea is neutral and the Caspian Sea is now cool. The Mediterranean is slightly warm.
The Tropical Pacific is NEUTRAL to La Nina in the Nino 3.4 Measurement area but neutral to the east connecting to land. That is a change.
The U.S. Great Lakes are slightly warm. The North Atlantic is warm. North of Scandinavia and to the east is it is very warm. The Northern and Western Gulf of Mexico is warm. The waters north of Antarctica East of South America are again cool.
I have some additional commentary on this static analysis of the anomalies below where I examine the four-week change in these anomalies. The list of Atlantic Multidecadal Oscillation (AMO) values can be found here.
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 over the last four weeks. 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 week's version of the graphic to the prior week and report on the differences below.
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 this week towards the Dateline the warming along the Equator is less impressive. The Pacific cooling trend north of 40N continues to be less intense to the west but more impressive off the Coast of CONUS reaching quite far south which is very significant. Northeast of Australia the trend is cooler which is strange for an ENSO Cool Event. The warming trend in the North Atlantic has stabilized. West of Africa in the Gulf of Guinea the trend has changed to warmer but remains cooler south of Africa. East of South American the cooling trend has intensified. 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.
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 December 6, 2016 Version and looking at Week 2 of that forecast.
Mostly I see for Week Two (this graphic updates on Tuesdays and I post on Monday which is almost a week later so Week Two applies unless I go back on Tuesday and update the discussion when the map updates), the period December 14, 2016 to December 20, 2016, it will likely be dry in Uruguay, wet and stormy south of Mainland Asia including to a lesser extent the Maritime Continent and Northwest Australia but dry further west in the Indian Ocean wet in South Africa.
Look at the Western Pacific in Motion.` When I published, this graphic was not being displayed but the website indicated that was a temporary outage.
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 ties in with the Week 1 forecast in the graphic just above the graphic. Information on Western Pacific storms can be found here. This is an unofficial private source but one that is easy to read.
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 geographical 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. It is probably not necessary to follow the discussion below, but here is a link to TAO/TRITON terminology.
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, in order 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.
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 -0.5C anomaly. So this is opposite to last winter but the intensity is a third or less of the situation last winter.
Location Bar for Nino 3.4 Area Above and Below
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
Degrees of Coverage
As of Today
May 23, 2016
As of Today
May 23 2016
As of Today
In Nino 3.4
Dec 12, 2016
May 23, 2016
These Rows Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly*
0C or cooler Anomaly
These Rows Show the Extent of the La Nina Impacts on the Equator
-0.5C or cooler
-1C or cooler Anomaly
-1.5C or cooler Anomaly
It is useful to start comparing the rightmost column to the column to the left of it. One can now usefully compare the current longitudinal extent of the water temperature anomalies with the situation on May 23, 2016. As of today the cool event is still more prevalent along the Equator than it was on May 23, 2016 although the greater extent re actually La Nina type values is only in the -0.5C to -1C category. To help us with this tracking I have created a new base point i.e. today December 12 so that is the additional column.
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 today again only 40 degrees of water anomalies cool enough to be a La Nina. Subtracting 40 degrees from the 50 degrees you end up with 10 degrees of ENSO Neutral and 40 degrees of water cool enough to qualify as La Nina i.e. temperature anomalies more negative than -0.5C. There are today 15 degrees of water along the Equator in the ONI Measurement that is -1C or less which would be cool enough to be a moderate La Nina when just looking at the Equator and there are 0 degrees of -1.5C water. 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 but not a way to calculate the Nino 3.4 value which I do below using a different approach. 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 cool anomaly is fairly well distributed within the Nino 3.4 Measurement Area but the cooler water below is not reaching the surface rapidly and is slowly dissipating.
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 Nino 3.4 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 December 12, in the afternoon working from the December 11 TAO/TRITON report, this is what I calculated. [Although the TAO/TRITON Graphic appears to update once a day, in reality it updates more frequently.]
Calculation of ONI from TAO/TRITON Graphic
A. 170W to 160W
B. 160W to 150W
C. 150W to 140W
D. 140W to 130W
E. 130W to 120W
Total divided by five subregions i.e. the ONI
(-1.3)5 = -0.3
(-1.5)5 = -0.3
My estimate of the daily Nino 3.4 SST anomaly is again -0.3 which remains an ENSO Neutral value. NOAA has reported the weekly Nino 3.4 to be a La Nina value at -0.6. There had been three weeks of NOAA reporting an ENSO neutral value for Nino 3.4. Looks like the Inactive Phase of the MJO gave NOAA a temporary reprieve. But I do not believe that their estimate is correct as a weekly estimate. Let's leave it at that.
Nino 4.0 is reported as being the same as last week at -0.2. Nino 3 is being reported the same at -0.5. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is now warmer at positive +0.3 back to the recent pattern. What is left of this Cool Event is now focused in about two cool spots which we report on elsewhere in this report.
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 table form but going back a couple of more years can be found here.
This is from a legacy "frozen" NOAA system meaning the software is maintained but not updated. It seems to show a cycle in the Nino 3.4 Index Values. I see that as I monitor the TAO/TRITON graphic. My best guess is that it is related to the MJO but it certainly is intriguing. If this was read like a stock chart one might conclude that there had been a triple bottom and an upside breakout. Below is a "frozen" version of this graphic that I prepared last week with the trend lines for the highs and lows added. We will soon see if this method of analysis has any value. .
It is kind of a declining wedge (bullish) with an upside breakout not able to move through the upside resistance at +0.4C. As expected we are now in a down phase of the cycle but most likely not piercing the bottom line drawn. Look above one graphic to the live version we see 7 down days. The pattern has been about 10 down days in the down phase so we will see later this week if the pattern continues and the observed bottom and turn up is at a level higher than the prior low value. .
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 snapshots 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 auto-updates daily because the SST Departures on the Equator do not change rapidly and the prettied-up version is so much easier to read. You can see that the cool anomaly (bottom of the Hovmoeller is vanishing right before our eyes with almost no blue, more white and now some yellow. This graphic explains to a large extent the small week to week changes in the Nino 3.4 Index Reading. Remember the +5, -5 degree strip around the Equator that is being reported in this graphic. So it is the surface but not just the Equator.
There has been a clear pattern of the Cool Anomaly vanishing in the western end of the Nino 3.4 Measurement Area and strengthening in the Eastern End. This has been perhaps accelerated by a mild Inactive Phase of the MJO. It is a slow process.
The Cool Event sure looks like it has peaked and is in decline. There are now other reasons to believe it is not temporary but the decline phase of this quasi-La Nina Modoki.
In recent weeks I have stopped showing the below graphic which is more focused on the Equator but looks down to 300 meters rather than just being the surface. There has until this week been almost no change from the prior week but over the last month there has been sufficient change to warrant including this graphic this week.
NOAA has now dashed-in the upwelling phase of the multiple Kelvin Waves that has created this pseudo-La Nina and you can see that it is playing out just as NOAA upgrades the status of this Cool Event. However a small cool area barely visible last week is now more clearly visible at 160W to 150W which has caused the Nino 3.4 reading to decrease slightly into La Nina range. On the other hand the cool water just to west is no longer showing on this graphic.
The life cycle of a La Nina is based on the reservoir of cool water that formed in the Eastern Pacific rising or mixing out or being warmed by sunshine or otherwise returning to a more normal temperature. Unlike an El Nino, there is no reinforcements from the west available to the Cool Event. So it is just a matter of time for the surface to return to ENSO Normal Limits. The currents in the subsurface are complex and there are winds impacting the surface so the exact process is difficult to forecast. So really the only issue here is will the process play out in December or in January. The white and yellow area is ENSO Neutral. So only that small blue area between 170W and 120W is in play right now. It is a very slim reed for those who conclude that we are in a La Nina.
Let us look in more detail at the Equatorial Water Temperatures.
We are now going to change the way we look at a three-dimensional view of the Equator and move from the surface view and an average of the subsurface heat content to a more detailed view from the surface down. Notice by the date of the graphic (dated December 9, 2016) that the lag in getting this information posted so the current situation may be a bit different than shown although this graphic was updated today so it is more current than usual. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.
And now the pair of graphics that I regularly provide. 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. At different times I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years except along the Equator where it is adjusted every five years) and how both measures are useful but for different purposes.
Re the top graphic, let us first look at surface temperature anomalies. The coolest water at the surface shows up only in very small non-connected areas. Water of La Nina coolness but not very intense shows up along the Equator from 170W to the Coast of Ecuador but with significant gaps of less cool water especially at 140W to 120W. The -1C water shows most strongly east of the Nino 3.4 Measurement Area not at all in the Nino 3.4 Measurement Area. Subsurface Temperature Anomalies: Notice that the cool anomaly in excess of -1C no longer exists within the Nino 3.4 Measurement Area (except for one small pocket) and appears to be rotating towards the coast and diminishing in size. How is this cool event to be sustained? It almost looks like 140W to 110W is about to go totally Neutral.
Notice the warm water at depth extending to west of 160W. We also see some pockets of warm water further east below the cool anomaly. It is not a Kelvin Wave but may be a sign of things to come. We may see a Kelvin Wave in January or February.
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 again located close to the Dateline at about 175E. This graphic does not show a 27.5C anomaly which might more precisely indicate where convection is likely to occur. The 27C isotherm has perhaps shifted back a bit to 165W. Notice the steepness of the 28C, 27C and 26C Isotherms but they are less steep than recently especially the 26C Isotherm. The 25C isotherm has moved east to 40W (and the 24C isotherm is over to 130W) indicating the decline of the Cool Event. The 20C Isotherm has moved close to the surface but is not reaching the surface this week. 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 Nino 3.4 Index. So it is still a battle going on with La Nina nudging ahead but not looking like it can sustain itself. It seems to have peaked and begun to decline.
The flattening of the Isotherm Pattern is an indication of ENSO Neutral just as the steepening of the pattern indicates La Nina or El Nino depending on where the slope shows the warm or cool pool to be.
Here are the above graphics as a time sequence animation. You may have to click on them to get the animation going.
Although I did not fully 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.
There is cool water from 170W to the coast of Ecuador. But the coolest water, however, is only reaching the surface in the Nino 3.4 Measurement Area in two very small areas one very small at around 165W to 160W and another at 140W to 135W. The cooler than -1C anomaly no longer exists near the surface in the Nino 3.4 Measurement Area . So there is not much chance of the Nino 3.4 readings rising dramatically any time soon. And there is warmer water under the cool anomaly extending continuously and strengthening all the way to 160W and pockets further east. The coolest water remains over to the east where La Nina is not measured by NOAA and it is moving away from the coast. This is probably not the best place to express the thought but this way of measuring an ENSO event leaves a lot to be desired. Only the surface interacts with the atmosphere and is able to influence weather. The subsurface tells us how long the surface will remain cool (or warm). Anomalies are deviations from "Normal". NOAA calculates and determines what is "Normal" which changes due to long ocean cycles and Global Warming. So to some extent, the system is "rigged". Hopefully it is rigged to assist in providing improved weather forecasts. But to assume that any numbers reported can be assumed to be accurate to a high level of precision is foolhardy. It is strange to me that the Asian forecasting services generally conclude that that this cool ENSO Phase is not a La Nina but a near La Nina and NOAA concludes it is a La Nina but they express their confidence in that declaration in percentages. It is the same ocean. The reported readings are very close but the Asian readings are generally slightly higher (less La Nina-ish) than the NOAA reading and their cut-off points for declaring a La Nina are a bit different and the parts of the Equator they look at are a bit different. It might be explained by what part of the ENSO pattern impacts their area of geography but it just seems to me that NOAA is a bit over eager. And I wonder why.
And now Let us look at the Atmosphere.
Low-Level Wind Anomalies near the Equator
Here are the low-level wind anomalies.
The Easterlies (the blue) are suddenly again no longer there in the Eastern Pacific probably because of MJO action. What we saw last week, the Westerlies between the Dateline and 160W and the Easterlies to the West of the Dateline are almost gone. It is fairly normal at this point. Some of the forecasts call for a weak Inactive Phase of the MJO followed by a weak Active Phase which should first enhance the Easterlies in the Eastern Pacific and then decrease the Easterlies in the Kelvin Wave Generation Area and create the conditions for a Westerly Wind Burst creating a Kelvin Wave. .
And now the Outgoing Longwave Radiation Anomalies which tells us where convection has been taking place.
This is the graphic used by NOAA to justify the upgrade in status of the Cool Event based on lack of cloudiness near the Dateline and to the east. In the above graphic, the area of convection had expanded westward consistent with the prior wind anomalies. But that expansion has ceased and convection is mostly between 120E and 160E. Attention NOAA: It is a Cool Event with the cool pool to the east and he warm pool to the west. That is what makes it a Near La Nina. But it is borderline and most meteorological agencies see it as below the threshold to be called a La Nina.
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 the extent to which the Atmospheric Air Pressure at Tahiti exceeds the Atmospheric Pressure at Darwin Australia when normalized 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.
90 Day Average
The 30-day average, which is the most widely used measure, as of December 12 is reported at -0.48 which is not much changed since last week and about as close to Neutral as possible. The 90-day average at +1.75 is less La Nina-ish than last week and again solidly Neutral. 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. (Sustained values over +7 are usually associated with La Nina and less than -7 are usually associated with El Nino). To some extent it is the change in the SOI that is of most importance. It had been increasing but may now be stabilizing or going down. That could change but for now the SOI is not signaling a La Nina but ENSO Neutral.
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. November was not particularly favorable for La Nina development and most likely neither will be December in terms of the MJO.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.The MJO being Inactive is more favorable for La Nina than the MJO being Active. But the MJO goes back and forth from being Active, Inactive, strong and weak so it has mostly a short-term impact. It is possible that a weak Inactive Phase of the MJO might be giving this dying La Nina a little reprieve but the forecast is that this will soon change to a weak Active Phase so it is not very significant other than on a weekly basis. .
Lately, the impact has been fairly muted. But the change in the SOI recently and some other changes suggest that we are having an Active Phase of the MJO even if such is not being reported and what we have is not the MJO but something else that is impacting the cool pool in a similar way as an Active MJO would. The forecast for the MJO is updated weekly and can be found here. If the MJO is not in its Active Phase then perhaps some other pattern is impacting the SOI and also shifting the cool pool to the east. We are also having a non-split fairly strong Jet Stream which is also consistent with an Active MJO. So I am calling it a Stealth MJO.
The MJO 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. But it may account for what seems like a cycling of the estimate of Nino 3.4 as the cool water is blown first to the west and then to the east. This impacts the upwelling also.
Forecasting the Evolution of ENSO
Here is the November 17, 2016 fully model-based version .
The preference for La Nina conditions in NDJ was a bit less than a week earlier when the report was based mainly on a survey of meteorologist. When I see DJF, I notice that January is the middle month in the DJF three-month period. Thus it seems that January is probably the last month that the models indicated that we will have Nino 3.4 values equal to or under -0.5. When I look at the slightly higher probability for Nino 3.4 to be -0.5 or less as compared to Nino 3.4 to be in the Neutral Range, I was not blown away by the probability that we would be in La Nina condition into 2017..We were at the time this IRI/CPC report was published past mid-November so to me the story-line should then have been the imminent end of the Cool Event rather than upgrading the Status of the Cool Event
Now we have the December early-month report from CPC/IRI which I call the reading of the tea leaves in that it is based on a combination of model results and a survey of the views of meteorologists. Here is the official description:
Figure 1 is based on a consensus of CPC and IRI forecasters, in association with the official CPC/IRI ENSO Diagnostic Discussion
Recently the early month analysis has been more favorable for a la Nina than the later in the month model-based analysis.I think meteorologists like action so they prefer either El Nino or La Nina to Neutral. But the models are dispassionate about it.
Here is the discussion that was released with the graphic.
During early December 2016 the tropical Pacific SST anomaly was near -0.5C, the threshold for weak La Niña. Also, most of the atmospheric variables across the tropical Pacific have been consistent with weak La Niña conditions, although subseasonal atmospheric variability has temporarily weakened some of them[Editor's Note: They were not there]. The upper and lower atmospheric winds have been suggestive of a strengthened Walker circulation, and the cloudiness and rainfall have also been consistent with weak La Niña conditions. The collection of ENSO prediction models indicates SSTs near the threshold of La Niña [Editor's Note: Close only counts in horseshoes] persisting through mid-winter, then weakening to cool-neutral by later winter.
These results suggest that January is about equally likely to be La Nina or Neutral. But the models and current data suggest that we are no longer in what properly would be called La Nina Conditions and an objective assessment would be taking a different tack than NOAA is taking. One wonders why they ignore even their own forecast model and why some of their data does not agree with data released by other meteorological agencies.
Here is the daily PDF and Spread Corrected version of the NOAA CFSv2 Forecast Model.
Notice the NOAA forecast (which is not generally recognized as a very accurate tool) shows the value of NINO 3.4 will enter the Neutral Range in December and remains less than 0C through the summer. Thus we should have expected that NOAA on December 8 would have lowered the La Nina Status to reflect ENSO Neutral. Even their own model tells them that this Cool Event is fading. Australia has declared that it will not happen. So one wonders what in the World is going on with NOAA?.
Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)
Discussion (notice their threshold criteria are different from NOAA but also their actuals are higher than recorded by NOAA and yet Nino 3.4 is standard. So someone is incorrect OR WORSE.)
La Niña no longer likely in the coming months
The El Niño–Southern Oscillation (ENSO) in the tropical Pacific Ocean remains neutral (neither El Niño nor La Niña). Although some very weak La Niña-like patterns continue (such as cooler than normal ocean temperatures and reduced cloudiness in the central and eastern Pacific), La Niña thresholds have not been met. Climate models and current observations suggest these patterns will not persist. The likelihood of La Niña developing in the coming months is now low, and hence the Bureau’s ENSO Outlook has shifted from La Niña WATCH to INACTIVE.
The Indian Ocean Dipole (IOD) also remains neutral (neither positive nor negative), as is typical at this time of year. When ENSO and the IOD are neutral they have limited impact on Australian climate.
The climate of Australia, and other countries around the tropical Indian Ocean and western Pacific Ocean, has been strongly influenced during the second half of 2016 by both a strong negative IOD in the tropical Indian Ocean (that ended in November) and the weak La Niña-like pattern in the tropical Pacific (which has eased). This combination of climate drivers contributed to Australia observing its wettest May to September on record in 2016.
We also have the most recent JAMSTEC November 1 ENSO forecast. There should be a new version in a week or so.
The model continues to show ENSO Neutral for the next two years (after what they call a weak La Nina Modoki ends). But the potential for an El Nino has been taken out of the forecast. The JAMSTEC Discussion is shown earlier in this report.
Indian Ocean IOD (It updates every two weeks)
The IOD Forecast is indirectly related to ENSO but in a complex way.
Indian Ocean Dipole outlooks
The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 4 December was −0.02 °C.
The influence of the IOD on Australian climate is weak during the months of December to April. This is because the monsoon trough shifts south over the tropical Indian Ocean changing wind patterns, which prevents an IOD pattern from being able to form.
However, the continued presence of much warmer than average water to the north and northwest of Australia may see continued influence on Australia, including enhanced rainfall.
D. Putting it all Together.
Looks like this Cool Event is no longer even properly described as "La Nina Conditions Apply".
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 may follow this ENSO Cool Event this summer or perhaps the Cool Event will last for one more year. The AMO is pretty much neutral at this point (but more positive i.e. warm than I had expected) 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.
E. Relevant Recent Articles and Reports
Weather in the News
It has been cold in the Northern Tier but this has been well covered (and exaggerated) in the media so I see no need to add to that discussion).
A quote from the PR release made it obvious to me what this was.
The researchers looked at how storms that occurred between 2000 and 2013 might change if they occurred instead in a climate that was 5 degrees Celsius (9 degrees Fahrenheit) warmer — the temperature increase expected by the end of the century if greenhouse gas emissions continue unabated.
"Continue unabated" and 5C were to me clearly an indication that this related to RCP 8.5 and indeed to the high-end estimate of the Temperature increase that would result if we followed that path of watts per square meter increase. Here and here are two links that explain the RCP system.
Then I talked to the author and he explained to me that:
We could not afford to simulate more than one future projection under the RCP 8.5 scenario since we are running our model on a 4 km grid which is computationally extremely expensive.
So although I have not confirmed it with the author, I am pretty sure the Media Dept at NCAR prepared the Press Release and the inadequate description in the Legend of the graphic.
It would be nice to have results for the more (IMO) realistic RCP of 4.5 and 6.0 but if we interpret the above graphic as what could happen in the extreme case, it is very useful. I am guessing that the percentages and shading would be less extreme but the locations would be similar.
The full paper is extremely interesting and informative. If you have access to the paper, I suggest that you read it. It provides the important caveats to the graphic but it also provides a lot of very useful information on how temperature and precipitation are correlated.
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.
G. Table of Contents 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.
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.
J FM 1951
ONI Recent History
The Aug/Sept/Oct reading has been issued and is currently listed as -0.7. The Sep/Oct/Nov preliminary estimate is -0.8 so there would now need for there to be two more periods of -0.5 or colder for this to be eligible to be formally recorded as a La Nina. I suspect there will be one more but not two. NOAA seems to be determined to make that happen. THEIR FUNDING MAY DEPEND ON THAT.
The full history of the ONI readings can be found here. The MEI index readings can be found here.
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