Of course "Normal" should always be interpreted as "The Current Normal". This is one of my favorite articles. The message was that the envelope of variability is changing. We have received a new Seasonal Outlook update from JAMSTEC and are showing their December 2016 - February 2017 maps with a link to their further-out forecasts. We will receive NOAA's updated 15-Month Outlook later this week. You will find the JAMSTEC forecast very interesting.
From Jeff Master's Weather Underground blog from last Tuesday. I provide it to show that in some cases weather predictions as far as five days in advance can be fairly reliable.
Ex-Typhoon Songda to drench Northwest U.S.
In the Northwest Pacific, Category 3 Typhoon Songda is heading northeast at 13 mph towards Alaska, and is expected to transition to a very wet extratropical storm with 45 mph winds on Thursday, when it will be a few hundred miles south of Alaska’s Aleutian Islands. Ex-Songda will then catch a ride with the jet stream and arrive off the coast of Washington on Saturday, when the storm is expected to intensify into a powerful low pressure system with a central pressure near 960 mb, bringing strong winds and heavy rains to the coasts of Oregon, Washington, and British Columbia. Rainfall of 6 to 10 inches, with local amounts over 12 inches, is possible western Washington south to northwestern California this week, due to a series of heavy rainstorms which include ex-Songda this weekend. East of the Cascades, rainfall could total 1 to 3 inches in the valleys and 3 to 7 inches in the foothills of the northern Rockies.
Here is the report of what has happened so far and the near-term forecast. It updates.
Let's talk about Global Warming a bit.
From the IPCC AR5 WGI
You can find this in the IPCC AR5 WGI Report but it is easier to find it here. There are other similar versions but this what was included in the IPCC AR5 WGI Report. Here is a newer version but I think it is showing the same thing but it is too busy for my eyes to read it. It does provide a number of useful links for those wanting to get more involved with this analysis.
Of great interest are the confidence intervals.
For Global Warming Skeptics, one could notice that the confidence intervals for some of these measurements exceed the confidence interval of the imbalance and the imbalance itself. The problem with that correct analysis of the data in the above table observation is that it is simply getting warmer. Thus arguing about confidence intervals being larger than the estimated mean change is a bit like having a discussion of life expectancies for an individual at their funeral. We have ground truth in the temperature record. The imbalance may actually be larger than shown. It may be increasing or decreasing. Although there are many ways to mitigate Global Warming some show up very obviously in the above graphic. If the tops of clouds and the Earths surface (including buildings in cities) were more reflective, the Imbalance would be reduced if not eliminated or even have a different sign. On the other hand, if there is more evaporation or more reflection to the surface from clouds, it works the other way. This is a very important and interesting graphic. One more thing. The imbalance is small: 0.2 to 1.0 Watts per meter squared with a mean of 0.6 watts per meter squared. It is correct that 0.6/340 is equal to 0.176 percent per year. That is a small amount but it is cumulative.
That is why I advise people not to be obsessed with finding evidence of Climate Change. It is a slow but inexorable process but slow. So changes are not obvious and attribution of strange events to Global Warming is very difficult if one is objective. That is why NOAA updates their anomaly base only once a decade except for every five years along the Equator to be more precise with ENSO. There is a lot of natural variability in weather so attempts to show that a particular event is due to Global Warming is very challenging from a statistical perspective. This week we ponder the question of the extent to which Warming has contributed to a robust cyclone season both in the Pacific and Atlantic. I expect much to be written on this and to a large extent I will provide links to those articles in the News Section of this Report but I will be skeptical about any claims of proof rather than statistical analysis. One can show that the distribution of events has changed more easily than one can show that a particular event is outside of the range of what might have occurred in the prior regime. If a baseball player hits 100 home runs in a season we may suspect that player is doing something more than spending a lot of time in the gym but we can not prove steroids unless they show up in a drug test. Even then the cause and effect is less than a certainty. It may be a different performance enhancing medication or an operation that installed a mechanical arm. Proof is more difficult than inference.
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 there is not a lot of moisture around CONUS other than the Northwest. But you can still see Nicole.
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.
Earlier today the forecasted Aleutian Low (in the Gulf of Alaska) had an hPa of 996 (the average in the winter is 1001 hPa and 994 hPa for a non-split Low). It is shown as split Low, actually three pieces, with a small weaker portion over by Kamchatka and a somewhat stronger one even beyond that which might not even be considered to be part of the Aleutian Low. The graphic changes every six hours. It looks a lot like what one might see with an El Nino and think about that when you get to the discussion of analogs re the 6 - 14 Day Forecast. At any rate this Low is what is creating the incoming moist air to the Northwest. The forecasted Low is much weaker than it has been in recent days.
The High Pressure off of California, the familiar RRR, is here but weak (1024 hPa) and kind of pushed to the side by this very aggressive Aleutian Low. The RRR continues to do a good job of protecting the West Coast from Pacific storms and also providing northerly winds for California. 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.
What you are seeing here is a projected major precipitation event for the Northwest but less strong than what was hyped earlier in the week. But the inland precipitation is very important due to the snow to precipitation ratio. We are now starting to see the QPF increasing for the Northeast.
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. This week we do not see the 540 line thinking about entering CONUS. Remember that 540 relates to sea level. Inland from the Northwest you re above sea level so snow is likely.
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 progression of the West Coast storm system with the West Coast trough impacting the East Coast by Day 7 with perhaps another Pacific Trough impacting CONUS a week from now. This is about as "Normal" as normal gets for this time of the year. .
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. The winds and moisture approaching the Northwest are of most interest.
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. 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 October 17, 2016 (and this is the current situation not an animation of recent history), as I am looking at the above graphic, we see mostly clouds along the Northern Tier. Water vapor imagery is a bit different than the above two graphics as it focuses on the water vapor in clouds rather than the clouds themselves.
Looking at the current activity of the Jet Stream.
One sees a lot of activity across the Northern Tier. As of now the entry point of the Jet Stream may be further south than recently forecast. Do you notice the gap re wind speeds between Oregon and Northern California? What is that all about?
Below is the forecast out five days.
Now let's look at the situation on Day 5 below. You can see the Deep Trough in the Jet Stream as it intercepts North America in British Columbia and Washington State and Oregon and then dips down into Arizona and New Mexico and then heads northeast towards the Canadian Maritimes. Well actually that is what the graphic looked like two days ago. Now it is shifted to the south and further East. Will the Jet Stream dip into the top of the Southwest on the way East or not? I suspect not but have not yet read the daily analysis from Flagstaff Arizona. Ok I just did and this is what they were thinking Monday AM which probably was a carryover from the Night Shift.
From Tuesday night through Wednesday morning, a dry cold front is forecast to sweep across northern Arizona causing a slight dip in temperatures and breezy northeast winds. A strong ridge is forecast to build over the Southwest on Thursday resulting in a slight warming trend and above normal temperatures heading into the weekend
So it looks like that over-hyped trough will not dip as far south as some might have hoped.
Researching further via the Salt Lake City NWS and their 9:32 PM Report Monday evening I find:
The upstream trough is expected to cross northern Utah tomorrow afternoon. This will bring a reinforcing cold front to the area as well as precipitation to northern Utah and southwest Wyoming. After that, an extended period of high pressure looks to settle into the area.
So that pretty well locates the trough passage at least in terms of how the local meteorologists are interpretting the forecasting model results.
Why we Pay Attention to the Jet Stream
This article provides some basic information on the Jet Stream. Remember that nature attempts to keep things in balance. So warm tropical air must move towards the poles to keep temperature gradients in balance. But Earth rotates and is shaped more like a sphere than a cylinder.
The momentum the air has as it travels around the earth is conserved, which means as the air that's over the equator starts moving toward one of the poles, it keeps its eastward motion constant. The Earth below the air, however, moves slower as that air travels toward the poles. The result is that the air moves faster and faster in an easterly direction (relative to the Earth's surface below) the farther it moves from the equator
The existence of a split Jet Stream is harder to explain and the below graphic shows it but does not explain it. It has to do partially with whether the Jet Stream is moving faster or slower than it needs to move to keep things in balance. If you understand why the Jet Stream behaves as it does you are very close to understanding weather.
In the winter, the Jet Streams play a very large role in our weather and tend to divide each hemisphere (northern Hemisphere shown in above graphic but substitute South Pole for North Pole and it works for the Southern Hemisphere) into three major circulation patterns as shown. CONUS weather takes place mostly in the Ferrel Cell which generally exists between 30N and 60N Latitude. The Hadley Cell is the circulation from the Equator to 30N which tends to be where the desert belts exist because air rises along the Equator and tends to subside in the vicinity of the 30N and subsidence is a drying process. The above is what is called a cartoon and it illustrates the principal but one would rarely see a pattern exactly as shown. If is for illustrative purposes only.
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 very important in understanding the impacts north and south of the Jet Stream which is shown as the higher speed part of the wind circulation. 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.
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 OND Outlook (for reference purposes), the Updated Outlook for the single month of October, the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 - 4 Experimental Outlook.
First - Temperature
Here is the Three-Month OND Temperature Outlook issued on September 15, 2015, 2016:
Here is the Temperature Outlook for October which was updated on September 30, 2016
6 - 10 Day Temperature Outlook
8 - 14 Day Temperature Outlook
Looking further out.
As I view these maps on October 17 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday, it appears that through November 11, the pattern during the second half of October will be warm for all but the West Coast and New England with a cool anomaly possibly related to where the Jet Stream is entering and passing over CONUS. That pattern is expected to continue as October ends and November begins except that the West Coast and South Florida will be EC and there are no cool anomalies shown. Alaska starts out being warm in the north and cool in the south but becomes all warm as we move into November and the storms in the Gulf of Alaska subside. 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 probability of being different from EC.
Now - Precipitation
Here is the three-month OND Precipitation Outlook issued on September 15, 2016 :
And here is the Updated Outlook for October Precipitation Issued on September 30, 2016
6 - 10 Day Precipitation Outlook
8 - 14 Day Precipitation Outlook
As I view these maps on October 17 (two of the five update each day and one (the Week 3 - 4 Outlook) updates every Friday, it looks like precipitation leading up to November 11 is tending for the second half of October to be wet in the Northwest with the wet anomaly extending across the north to the Great Lakes as the month evolves and perhaps also extending further to the south. The pattern is projected to evolve in the first half of November to be a dry Southeast but not including Florida with the Northwest and Great Lakes remaining wet. Alaska will start with a complicated pattern and morph to only the coastal areas being wet with the rest being EC. For CONUS it is forecast to be mostly EC except for the three anomalous areas mentioned. 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 probability of being different from EC.
Here is the NOAA discussion released today October 17, 2016.
6-10 DAY OUTLOOK FOR OCT 23 - 27 2016
TODAY'S MODEL SOLUTIONS ARE IN FAIR AGREEMENT ON THE 500-HPA FLOW PATTERN PREDICTED OVER THE FORECAST DOMAIN. TROUGHS ARE PREDICTED BY ALL SOLUTIONS OVER THE NORTHEASTERN CONUS AS WELL AS OFF THE COAST OF WESTERN NORTH AMERICA. IN BETWEEN THESE TWO TROUGHS, MOST SOLUTIONS PREDICT WEAK RIDGING ACROSS THE CENTRAL CONUS. HOWEVER, THE DETERMINISTIC 0Z ECMWF PREDICTS A MORE AMPLIFIED SOLUTION, WITH STRONGER RIDGING OVER THE CENTRAL CONUS, WHILE THE 0Z CANADIAN ENSEMBLE MEAN FORECASTS LESS AMPLIFICATION, WITH ZONAL FLOW ACROSS MOST OF THE CONUS. A COMPLEX FLOW PATTERN IS FORECAST OVER THE ALASKA SECTOR. A TROUGH IS PREDICTED OVER EASTERN ALASKA WHILE RIDGE IS PREDICTED UPSTREAM OVER EASTERN SIBERIA. AN ENHANCED JET IS FORECAST NEAR OR JUST SOUTH OF THE ALEUTIANS RESULTING IN FORECAST ANOMALOUS SOUTHWESTERLY MID-LEVEL FLOW ACROSS MUCH OF THE ISLAND CHAIN. THE GREATEST WEIGHTS IN THE 500-HPA MANUAL HEIGHT BLEND WERE GIVEN TO THE 0Z AND 6Z GFS ENSEMBLE MEANS DUE PRIMARILY TO ANALYSIS OF ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERNS MATCH CASES THAT HAVE OCCURRED IN THE PAST.
BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE NORTHEASTERN CONUS IN ASSOCIATION WITH A PREDICTED TROUGH. FORECAST RIDGING LEADS TO ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR THE CENTRAL CONUS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR WESTERN ALASKA DUE TO PREDICTED RIDGING AND ABOVE NORMAL SEA SURFACE TEMPERATURES. CONVERSELY, THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR THE PANHANDLE AND PARTS OF SOUTHEASTERN MAINLAND ALASKA IN ASSOCIATION WITH A FORECAST TROUGH.
ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE WEST COAST OF THE CONUS AHEAD OF A TROUGH PREDICTED OVER THE EASTERN PACIFIC. FORECAST RIDGING LEADS TO ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR THE SOUTHERN PLAINS. BELOW MEDIAN PRECIPITATION IS ALSO FAVORED FOR THE SOUTHEASTERN CONUS DUE TO PREDICTED SURFACE HIGH PRESSURE. CONVERSELY, ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION ARE INDICATED FOR PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GFS AND ECMWF ENSEMBLE MEMBERS. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR SOUTHWESTERN ALASKA (INCLUDING THE ALEUTIANS) IN ASSOCIATION WITH ANOMALOUS SOUTHWESTERLY MID-LEVEL FLOW. THERE ARE ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR PARTS OF NORTHWESTERN ALASKA IN ASSOCIATION WITH A PREDICTED RIDGE. NEAR TO ABOVE MEDIAN PRECIPITATION IS FAVORED FOR SOUTHEASTERN MAINLAND ALASKA AND THE PANHANDLE IN ASSOCIATION WITH A PREDICTED TROUGH.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO FAIR MODEL AND TOOL AGREEMENT.
8-14 DAY OUTLOOK FOR OCT 25 - 31 2016
DURING THE WEEK-2 PERIOD, MODEL SOLUTIONS INDICATE HIGH UNCERTAINTY, WITH ENSEMBLE MEAN FORECASTS SHOWING WEAK 500-HPA ANOMALIES OVER THE CONUS AND ENSEMBLE SPREAD GREATER THAN USUAL. MOST MODEL SOLUTIONS FORECAST ZONAL FLOW ACROSS MUCH OF THE CONUS SUGGESTING THAT AIR OF PACIFIC ORIGIN MAY DOMINATE DURING THIS TIME PERIOD. FARTHER TO THE NORTH, A TROUGH IS PREDICTED OVER THE GULF OF ALASKA WHILE AN ENHANCED JET IS FORECAST JUST SOUTH OF THE ALEUTIANS. ABOVE NORMAL HEIGHTS ARE PREDICTED OVER MUCH OF THE HIGH LATITUDES CONSISTENT WITH A NEGATIVE AO INDEX FORECAST BY MOST GEFS ENSEMBLE MEMBERS. THE WEEK-2 MANUAL 500-HPA HEIGHT BLEND IS COMPOSED ENTIRELY OF THE ENSEMBLE MEAN SOLUTIONS AND IS BASED ON CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE CENTRAL AND SOUTHEASTERN CONUS IN ASSOCIATION WITH RIDGING PREDICTED EARLY IN THE PERIOD. THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR PARTS OF THE NORTHEASTERN AND WESTERN CONUS IN ASSOCIATION WITH PREDICTED BELOW NORMAL HEIGHTS. THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR WESTERN AND NORTHERN ALASKA CONSISTENT WITH GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLE MEMBERS.
ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE WESTERN AND CENTRAL CONUS DUE TO ANTICIPATED MOIST PACIFIC FLOW. THERE ARE ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR PARTS OF THE NORTHEASTERN CONUS DUE TO SUBSIDENCE BEHIND A TROUGH FORECAST NEAR THE CANADIAN MARITIMES. PREDICTED MEAN SURFACE HIGH PRESSURE LEADS TO ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR PARTS OF THE SOUTHEASTERN CONUS. CONVERSELY, ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE ALEUTIANS AND SOUTHWESTERN MAINLAND ALASKA DUE TO THE PROXIMITY OF THE PREDICTED MEAN STORM TRACK. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR THE PANHANDLE AHEAD OF A TROUGH PREDICTED OVER THE GULF OF ALASKA. NEAR TO BELOW MEDIAN PRECIPITATION IS FAVORED FOR NORTHERN ALASKA TO THE NORTH OF THE PREDICTED MEAN STORM TRACK.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO LARGE SPREAD AMONG ENSEMBLE MEMBERS AND A PREDICTED LOW AMPLITUDE FLOW PATTERN ACROSS MUCH OF THE FORECAST DOMAIN.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON OCTOBER 20
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.
Sept 28, 1953
Oct 11, 1962
Oct 12, 1962
Oct 24, 1963
Oct 30, 1975
Following strong 1972/73 El Nino
Oct 19, 1979
Modoki Type II
Oct 20, 1979
Modoki Type II
Oct 31, 1984
Sept 30, 2005
(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 September 28 to October 31 which is thirty -three days which is a fairly large 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 October 15. These analogs are centered on 3 days and 4 days ago (October 13 or 14). So the analogs could be considered in sync with the calendar meaning that we will be getting weather that normally would occur this time of the year including that forecasted Western trough which is typical 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 are this time four El Nino Analogs (why are there any?), only two La Nina Analogs, and three ENSO Neutral Analogs. The phases of the ocean cycles in the analogs point towards any of the McCabe Conditions other than McCabe Condition "C". That is consistent with the 6 - 14 Day Forecast and adds confidence to the 6 - 14 Day Forecast. But having both El Nino and La Nina analogs raises many questions.
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.
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 the middle of October, I have now removed the July and August Graphics.
Here is the 30 Days ending October 8, 2016
The Precipitation and Temperature departures are almost identical to the prior 30 Day Graphic not sown. We should keep in mind that this represents the addition of only seven recent days and the removal of seven more distant days but still the lack of change is amazing. One change I see is to the Northwest.
And the 30 Days ending October 15, 2016
Re precipitation, you see some difference in the Northwest and some difference on the East Coast but less than what one might expect. Re temperature the warm anomalies are a bit muted. Remember this is a 30 day average with seven recent days added and seven days more than 30 days ago removed so the change is slow.
NOAA updated their Seasonal Outlook on September 15. We reported on that on Sunday Sept 18. You can read that report here. If you opt to go read my Report on NOAA's Seasonal Outlook Update, please return from there to read this report which you can do by simply hitting your "backspace" button on your keyboard. We will issue a new Update on the NOAA Seasonal Outlook sometime after Thursday.
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 hitting your "backspace" key which 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
Looking Out a Few Months
This is the precipitation forecast from Queensland Australia.
It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. Notice that the rising SOI triggers a lot of wet around the World. Look for low grain prices.
JAMSTEC issued their Precipitation Forecast recently based on the October 1, 2016 ENSO analysis. Notice this forecast is for December 2016 through February 2017.
It is pretty interesting especially for Southern Europe, Southeast Asia, Southern Africa especially to the west, South America, and a standard but muted La Nina Pattern for CONUS extending into British Columbia.
Here I just focused on Europe and CONUS
Kind of Dry! For the most part. Remember this is December 2016 through February 2017
Here is the temperature forecast
Northern Europe will be cool as well as parts of Northern Australia and Brazil and Kamchatka which could be important. Other than that, Global Warming Deniers might have to seek higher elevations.
There is a discussion that goes with it and that discussion was released today:. .
Oct. 17, 2016
Prediction from 1st Oct., 2016
According to the SINTEX-F prediction, the current weak La Niña Modoki will start decaying and the tropical Pacific will return to a normal state by boreal spring. 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 start decaying and disappear in boreal winter. A positive Indian Ocean Dipole may evolve in early summer of 2017. However, it is still uncertain at the present stage.
In boreal winter, as a seasonally averaged view, most part of the globe will experience a warmer-than-normal condition, while some parts of Brazil, northern Europe, and northern Australia will experience a colder-than-normal condition.
According to the seasonally averaged rainfall prediction, eastern China, Indo-China, East Africa, most parts of Europe, U.S. and the Far East (including Japan) might experience a drier condition during boreal fall, while most parts of Brazil, southern West Africa, western Central Africa, and South Africa will experience a wetter-than-normal condition. Australia will receive above normal rainfall during austral summer. Most parts of Japan will experience above normal temperature and below normal precipitation (less snowfall) in winter. Those may be associated with a warm Indian Ocean and a weak La Niña Modoki in the Pacific.
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. The graphic issued Sunday differs greatly along the Equator in the Eastern Pacific from what I saw Saturday so I do not know if the Oceans Changed or NOAA changed.
Remember this discussion is all about anomalies not absolute temperatures...so it is deviation from seasonal norms.
The waters off of Japan remain warm but perhaps not as warm and one sees some cool anomalies. South of Kamchatka Siberia the color on the graphic is less intense and if anything cool. The Central Indian Ocean is now basically neutral all cool. The southern coast of Australia is very cool but the Southeast Coast is warm. Water northwest of Australia is warm but not very warm. The waters south of Africa are warm to the west but a bit cool to the east. .
The overall Northern Pacific looks to be PDO Positive (the horseshoe pattern with the cool anomaly inside the horseshoe shape there but not very prominent). 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. Just out, September is initially estimated at -1.06 WOW and August was adjusted to -0.87. and July to +0.12 and June to +0.76. 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 waters west of CONUS are now neutral. This is not a good sign for a wet winter for mid latitudes. Further north, the Gulf of Alaska is quite warm with the Bering Straits even warmer. The Pacific being warm north of 50N remains an impressive feature of the overall pattern and suggests a wet Northwest and northern tier for CONUS this winter. To repeat, the water off of Baja California is no longer warm and that is why cyclones moving up the west coast have dissipated rapidly. But the Gulf of California and south is warm west of Mexico.
The Black sea, the Caspian sea and the Mediterranean are close to neutral except for the western Mediterranean which is quite warm.
The water directly west of South America is not showing much of a strong La Nina pattern even though NOAA is not noticing that much. There is a narrow cool anomaly in the Pacific right along the Equator in the La Nina Measurement Area. Recently it has appeared to be more robust though still gradually stretching west where it had crossed the Dateline but seems to have withdrawn on this graphic. It is perhaps 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. The water off the West Coast of Central America is warm.
The water off the East Coast of CONUS is warm but less so than recently. The Western Gulf of Mexico is warm. Further north in the Atlantic east of Newfoundland the North Atlantic is warmer than normal. The cool anomaly further south again shows and seem to be enlarging. There is a weak warm anomaly off shore of Northwest Africa. The waters north of Antarctica East of South America are uniformly colder than climatology and we again see the small warm anomaly 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. 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. 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 an overall reversal in the cooling trend along the Equatorial Pacific reducing credence to there being a La Nina developing. Other features are less cooling south of Africa, less warming southeast of Australia cooling off the east coast of North America. The Gulf of Alaska is cooling. There seems to be a shift from west to east at that latitude re the rate of cooling with it being more rapid in the Eastern Pacific. I have not seen the September PDO Index reading but this looks less PDO Positive to me. 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.`
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. It also shows what is headed back towards CONUS.Right now we see yet another Typhoon headed for Asia. Information on Western Pacific storms can be found here. This is an unofficial private source but one that is easy to read. Their focus has been on Typhoon Sarika / Karen which will already have hit the Philippines by the time my report is published Monday Night but continue to head to the west and impact SE China and Indochina. But right behind Typhoon Sarika/Karen is Typhoon Haima.
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 October 11, 2016 Version and looking at Week 2 of that forecast.
Mostly for the period October 19, 2016 to October 25, 2016, I see in week two that it will be likely wet for the Maritime Continent with a risk of cyclone development east of Central America.
I rarely comment here on week one as I publish late on a Monday and most read the report Tuesday afternoon more or less when this graphic updates so what I see as Week 1 is gone by then and what I discuss as Week 2 is updated and shown as the new Week 1. I could go back into my article late on Tuesday and update the above discussion but I think that readers can interpret this graphic on their own after it updates as the Legend is very easy to understand.
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 -1C 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
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
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. There today only 15 degrees of water along the Equator in the ONI Measurement that is even -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. 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 October 17, in the afternoon working from the October 16 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
(-5.2)5 = -1.0
(-2.7)/5 = -0.5
My estimate of the daily Nino 3.4 SST anomaly has increased marginally to -0.5 which is a borderline La Nina value. NOAA has reported the weekly ONI to be -0.6 which is much less cool than they reported last week but still a La Nina value. This week my estimate and their estimate are very similar.
Nino 4.0 is reported as being slightly warmer than last week at -0.4. Nino 3 is being reported quite a bit warmer at -0.1. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is being reported the same as last week at +0.1.
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. NINO 1+ 2 stubbornly remains slightly positive and determines the weather of Ecuador and Peru. It has never been other than ENSO Neutral for the Coast of Peru and Ecuador.
This is from a legacy "frozen" NOAA system meaning it 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. It might explain to some extent the divergence between my estimate on Monday night which is based on the Sunday TAO/TRITON Graphic and the NOAA report on Monday which is a weekly estimate of the Nino 3.4 values. I have attempted to mentally integrate the above to see if I get back to the NOAA estimates but with only fair success.
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 Departures on the Equator do not change rapidly and the prettied-up version is so much easier to read. You can see that the blue cool anomaly has again moved further west and the dark blue which was not showing last week (look up a tad) is now again showing at the bottom which means the current reading. You can see that the yellow ENSO Neutral water in the Eastern Pacific which had been replaced by blue is again mostly yellow and that is important. You can also see that on this graphic the blue area at about 160W is smaller but it does not show that way on some other graphics. You can see the steady westward shift in that anomaly but so far it has not shifted out of the Nino 3.4 Measurement Area. This graphic explains to a large extent the week to week changes in the Nino 3.4 Index Reading. Remember the +5, -5 degree strip around the Equator that is being measured. So it is the surface but not just the Equator.
In recent weeks I have thought it would be useful to show a view which is more focused on the Equator but looks down to 300 meters rather than just being the surface. Here you can clearly see the cool blob (darker blue) at 170W to 155W which is the focus of this cool event. There was almost no change from last week so I omitted that graphic this week.
Let us further 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 and an average of the subsurface heat content to a more detailed view from the surface down.
Current Sub-Surface Conditions. Notice by the date of the graphic that the lag in getting this information posted so the current situation may be a bit different than shown. 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 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. At different times and today in particular, 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) and how both measures are useful but for different purposes.
The top graphic shows surface temperature anomalies. The coolest water at the surface shows up only in 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. The -1C water shows most strongly between 175W and 150W. There is a gap between 150W and 120W (the eastern end of the Nino 3.4 Measurement Area) although that gap does not show up fully 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 with actually some showings of warm water. Notice that there is very little water with a cool anomaly in excess of -2C. How is this cool event to be sustained?
Notice the warm water at depth west of 165E.
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 at just west of 180 i.e. The Dateline 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 has shifted west a bit to 175W so we do not have ideal conditions for significant convection along the Equator east of the Dateline which is a characteristic of a cool event. Notice the steepness of the 28C, 27C and 26C Isotherms. This is a real boundary between warmer water and cooler water. The 25C isotherm is again at 140W which is similar to last week. The 20C Isotherm has moved close to the surface but is not reaching the surface and has not changed in weeks. 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. 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.
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 from 170W to 150W which is about the same as last week. It is a bit more the 20 degrees as the cool water extends a bit further west than 170W and bit further east than 150W. What remains surprising is the failure of the cooler water east of 150W to rise to the surface. Not of course it is complicated by the fact that is what is shown here is temperature anomalies not absolute temperatures but still this cool event refuses to record as a clear cut La Nina but just hovers at the threshold. .
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 becoming prominent.
And now the Outgoing Longwave Radiation Anomalies which tells us where convection has been taking place.
In the above graphic, there is now almost no convection along the Equator but the small area is a bit more intense.
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.
90 Day Average
The 30-day average, which is the most widely used measure, as of October 17 is reported at +5.93 which is a tremendous decline from last week and is technically a La Nina level but for those who believe the trend is what counts this is not a sign of La Nina. The 90-day average at +7.65 is the same as last week and is again at a La Nina level. These seem to be possibly 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. 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.
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. September was not particularly favorable for La Nina development and most likely neither will be October 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 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.But it may account for what seems like a cyclicling 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
The below is the Late September CPC/IRI which is more tied to model results without interpretation followed by the "Probabilistic Forecast issued this week which includes a large component of input from meteorologists as compared to the second forecast in the month . 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)
So first we have the previously released mid-month model-based report
This was a bit more bullish on La Nina happening than the early September analysis. Kind of a big change in a week. It still was pretty much a coin flip with the projected strength of this cool event being marginal for ruling in or out as being a La Nina Event.
And now the recently updated meteorologist Consensus version
This is a lot more bullish on La Nina happening. Kind of a big change. there are two issues with this analysis. First of all the meteorological agencies in other nations do not see it this way and the second issue is duration. The above analysis only show that La Nina conditions are favored through DJF. I also expect that the next edition of this analysis will look very different.
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.
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 a few weeks weeks it looked like it no longer seemed to be but now suddenly it does albeit barely but now almost to a moderate level. 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. 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 I am not so sure of that in recent weeks 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. It is a cool event pattern but not at all extreme.
Here is the Nino 3.4 report from the Australian BOM
We also now have the most recent JAMSTEC October 1 ENSO forecast.
The model continues to show ENSO Neutral for the next two years.
Not directly related to ENSO is the IOD Forecast:
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 and in the end NOAA may turn out to have correct. 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 but perhaps as few as zero as in we may have seen the PDO change phase with this recent El Nino.
Some are disappointed that Matthew was not more destructive. On the one hand the number of Atlantic Hurricanes has been on a declining trend. On the other hand this is I think the first time we had both in the Atlantic and Pacific a Category 4 and 5 cyclone. So the jury is out on this but the oceans are warming so there may be more powerfully ocean storms. The article above is related to this.
Reported last week and I am repeating the below because it is very important.
Southwest Mega-drought Risk - Needs to be read carefully. An important issue is the validity of RCP 8.5 as a benchmark. Here is a good article on that. It has page after page of comments so here may be a shorter version with somewhat fewer comments.
I need to really thoroughly review this very important article and that will take some time. But here are some initial thoughts.
I did want to mention that under the McCabe et al analysis, one of the four combinations of ocean phases was a drought phase so that suggested that for approximately 25% of the time the chances of drought were very good. Thus one would have expected a significant drought once a century. So that is not new information.
McCabe et al also calculated a change in the situation due to Warming. That is not new information either.
So although this new analysis is more recent than the older analysis which was just after the PDO and AMO were figured out, to me it is not very different. The main difference is this paper has scenarios for the future. One probably could have developed them from the McCabe et al analysis. And they are talking about 35 year droughts which is not all that different from the droughts we have had once per century. My quick reading of the article did not come across the mention of El Nino. Are they in the analysis? I need to read more.
The authors make things simple with basically 2C, 4C, and 6C scenarios. How the 2C is defined is important. Apparently it is mean warming from 2051 to 2100 compared to 1951 to 2000. I like to use simple approaches so my mind I will think about it as 2075 compared to 1975. There are other papers that use a different way of measuring 2C (and 4C and 6C). Some go back to 1750 or the beginning of the Industrial Revolution. Well if 1975 is the base even if the growth rate is steeper then linear there is still some room to get to 2C. We are about 40 years into the 100 year period used by the authors.
More when I have had a chance to really study this important paper.
The below is the key graphic:
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 official reading for Jul/Aug/Sept is now reported as -0.5.The JAS reading is the first La Nina Value. So there would now need for there to be four more periods of -0.5 or colder for this to be eligible to be formally recorded as a La Nina. It is possible but it will be close. I doubt that it will happen.
The full history of the ONI readings can be found here. The MEI index readings can be found here.
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