Written by Sig Silber
Winter has arrived. El Nino has arrived even as it has started to decline in strength. But it is plenty strong and the southern branch of the Jet Stream is active and will have significant impacts on the Southern Tier of the U.S. for the next three months. The balmy weather enjoyed by the East Coast may soon gradually come to an end especially for the Mid-Atlantic. It is all part of the ENSO Cycle and perfectly normal.
This is the Regular Edition of my weekly Weather and Climate Update Report. Additional information can be found here on Page II of the Global Economic Intersection Weather and Climate Report.
Let’s Focus on the Current (Right Now to 5 Days Out) Weather Situation.
A more complete version of this report with daily forecasts is available in Part II. This is a summary of that more extensive report. This link Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks will take you directly to that set of information but it may take a few seconds for your browser to go through the two-step process of getting to Page II and then moving to the Section within Page II that is specified by this link.
First, here is a national animation of weather front and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at the link provided above.
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.
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. Right now a trough is shown for the East Coast but there are some questions about how far down that trough from Canada will extend. Since I last looked, there is now another trough forecast for the Southwest. 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 thickness lines are not below 540 for many areas in CONUS. The 540 Level general signifies equal chances for snow at sea level locations. This suggests that snow is still not ready to be routine in CONUS other than in mountainous regions and where these storms are impacting which has led to a large area that is snow covered. The level of storm activity in the Western Pacific is picking up as the MJO transitions to its active phase. Notice the Northern Pacific is like a giant anticyclone with clockwise motion so that which gets sent west due to El Nino is to some extent returned to North America but at higher latitudes.
As I am looking at the below graphic Monday evening December 28, I still see a pattern which is much more active in the Northern part of CONUS than the Southern Tier. Looks like the recent Southwest Storm have moved into the Great Lake area and the Northeast.This graphic updates automatically so it most likely will look different by the time you look at it.
Below is an analysis of projected tropical hazards and benefits over an approximately two-week period. I am now only showing one view as NOAA seems to be updating only one of the two graphics but fortunately it is the one that shows both the Pacific and the Indian Ocean.
This graphic is scheduled to update on Tuesday and I am reading the Dec 22, 2015 Version and looking at Week 2 of that forecast. Mostly I see for the period December 30 – January 5, 2016 below average precipitation for the Maritime Continent with a hint of possible cyclone activity off the coast of Northeast Australia. The forecast also calls for moderately dry conditions in Brazil.
Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 6 (the Day 3 forecast is available on Page II of this Report). This graphic also auto-updates. In recent weeks, the projected location and strength of the Aleutian Low has varied a lot. On some days, the forecast is showing a split low with each of the two lows weaker than a combined single Low. Right now the forecasted Low has an hPa of 976 which is intense (the average in the winter is 1001hPa and 994 hPa for a non-split Low). It is a single low and located a bit further to the west than is ideal for El Nino. The rapidly shifting position of the Low makes a big difference. With this forecast, one can see how on Day 6, Pacific storms can not easily enter CONUS south of Canada or the Northwest. So most of the activity now comes from the Southern Branch of the Jet Stream but the most recent storm found away to drop south so all things are possible. A longer discussion of the climate of Beringia and the role of the Aleutian Low is in Part II of this Report: 2. Medium Frequency Cycles such as ENSO and IOD.
Looking at the current activity of the Jet Stream one can certainly see the northern entry point for the Jet Stream which is not characteristic of El Nino. But the southern branch has been very active. Also the Jet Stream is now diving to the south creating the trough that is bringing storm systems to the Southwest and along the West Coast. The Southerly Track of the Jet Stream recently impacted New Mexico where I live. Because when a Low, which is a cyclone, passes to the south of NM, it produces easterly winds that create orographic lift on the eastern side of the Rocky Mountains. That is unusual but it happens and it quickly fills up the motels on Interstate 40 which gets shut down.
And the forecast out five days. Of course this is a forecast and changes daily or perhaps even more frequently. If this pattern plays out as forecast here, the next set of storms may pass to the south of California, Arizona, and New Mexico but hit Texas and from the north there may be stormy weather in the Great Lakes area. But not all weather is controlled by the Jet Stream (which is a high altitude phenomenon) but it plays a major role in steering storm systems.
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.
And when we look at Sea Surface anomalies below, we see a lot of them not just along the Equator related to El Nino. The slight gap between the El Nino warm anomaly and the Coast of Ecuador is of interest since this is a daily chart and more up to date than some other sources of information.
The two graphics below show first the changes over the four weeks (ending November 4) as compared to the above graphic which shows the current SST anomalies and then the changes over the four weeks ending on December 16, 2015. Looking at both of these change in anomaly graphics is helpful in putting the current situation shown above into perspective.
First the four weeks ending on November 4, 2015
I am also showing the new version issued today which basically shows the changes over the last month in the Sea Surface Temperature anomalies. It is approximately seven weeks later than the above graphic which you can tell by checking the dates in the graphic. You can clearly see the cooling pattern in the Pacific and since these are “departures” or “anomalies”, it is not a seasonal pattern that is being shown. The warm anomaly in the Western Pacific along the Equator is gone. In between the prior reading and this reading, the water along the Eastern Pacific warmed but this has now diminished except in the furthest east part of the Pacific indicating the weakening of the El Nino. The waters around Australia have cooled. There is now a warm swath between Africa and the East Coast of South America but I do not know how to interpret that. The cool anomaly off of Northern Africa is gone. The cool anomaly off of Beringia has greatly diminished. These are major changes.
Now let us focus on the 6 – 14 Day Forecast for which I generally only show the 8 – 14 Day Maps. The 6 – 10 Day maps are available in Part II of this report.
To put the forecasts which NOAA tends to call Outlooks into perspective, I am going to show the three-month JFM and the “early” single month of January forecasts and then discuss the 8 – 14 day Maps and the 6 – 14 Day NOAA Discussion within that framework.
First – Temperature
Here is the Three-Month Temperature Outlook issued on December 17, 2015:
Here is the “Early Released” January Temperature Outlook issued on December 17, 2015.
Below is the current 8 – 14 Day Temperature Outlook Map which will auto-update and thus be current when you view it. It covers the week following the current week. Today’s 6 – 14 Day Outlook is just nine days of the month and the map shown below of the 8 to 14 day Outlook only shows seven days. The 6 – 10 Day Map is available on Page II of this report. As I view this map on December 28 (it updates each day), it appears that the start of January may continue to have the east/west divide relative to temperature anomalies rather than the north/south divide more typical of an El Nino which is shown in the full month NOAA Outlook for January. Also taking the 6 – 10 Day Outlook which you can find on Page II of this Report into account, it seems that the Mid-Atlantic will not be consistently warmer than climatology in early January.
Now – Precipitation
Here is the three-month Precipitation Outlook issued on December 17, 2015:
And here is the month of January “Early Release” Precipitation Outlook which was issued on December 17, 2015.
Below is the current 8 – 14 Day Precipitation Outlook Map which will auto-update and thus be current when you view it. It covers the week following the current week. Today’s 6 – 14 Day Outlook is just nine days of the month and the map shown covers seven days of the nine. The 6 – 10 Day Map (the two maps overlap) is available on Page II of this report. As I view this map on December 28 (it updates each day) it appears that the start of January may be a wetter in the Southern Tier and drier in the Northern Tier than the full-month outlook. But this forecast, unlike the temperature outlook, is much more volatile and changes a lot from day to day as NOAA tries to keep up with the vagaries of the Jet Stream.
Here are excerpts from the NOAA discussion released today December 28, 2015. It covers the full nine-day period not just the seven days shown in the 8-14 Day Map.
6-10 DAY OUTLOOK FOR JAN 03 – 07 2016
TODAY’S NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED 500-HPA FLOW PATTERN ACROSS MUCH OF THE FORECAST DOMAIN. SPLIT-FLOW IS PREDICTED OVER NORTH AMERICA. TROUGHS IN THE NORTHERN STREAM ARE FORECAST OVER THE ALEUTIANS AND OVER EASTERN CANADA, WHILE A RIDGE IS PREDICTED OVER WESTERN CANADA AND ALASKA. FARTHER TO THE SOUTH, AN ACTIVE JET STREAM IS FORECAST TO TRAVERSE MUCH OF THE SOUTHERN TIER OF THE CONUS. TODAY’S OFFICIAL MANUAL 500-HPA HEIGHT BLEND IS COMPOSED PRIMARILY OF THE ENSEMBLE MEAN SOLUTIONS FROM THE ECMWF, GFS, AND CANADIAN DUE, IN LARGE PART, TO CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE PREDICTED PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR ALASKA AHEAD OF THE TROUGH PREDICTED OVER THE ALEUTIANS. CONVERSELY, GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLES FAVOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE NORTHWEST CONUS EXTENDING SOUTHEAST TO PARTS OF THE SOUTHERN PLAINS. PROBABILITIES OF BELOW NORMAL TEMPERATURES ARE ENHANCED RELATIVE TO GUIDANCE FOR PARTS OF THE SOUTHERN AND CENTRAL PLAINS DUE TO SNOW COVER CONSIDERATIONS. BELOW NORMAL TEMPERATURES ARE ALSO FAVORED ALONG THE GULF COAST REGION CONSISTENT WITH GEFS REFORECAST GUIDANCE AND ANALOGS FROM THE MANUAL BLEND. THERE ARE ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR THE GREAT LAKES REGION AND PARTS OF THE NORTHERN PLAINS DUE TO PREDICTED ABOVE NORMAL 500-HPA HEIGHTS.
A PREDICTED ACTIVE SOUTHERN STREAM LEADS TO ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR THE SOUTHWESTERN AND SOUTH-CENTRAL CONUS. BELOW MEDIAN PRECIPITATION IS FAVORED FOR THE NORTHWEST AND NORTH-CENTRAL CONUS TO THE NORTH OF THE PREDICTED MEAN STORM TRACK. BELOW MEDIAN PRECIPITATION IS ALSO FAVORED FOR MUCH OF THE EASTERN CONUS IN ASSOCIATION WITH PREDICTED SURFACE HIGH PRESSURE. THE EXCEPTION IS FOR MUCH OF THE FLORIDA PENINSULA WHERE ABOVE MEDIAN PRECIPITATION IS LIKELY AROUND THE PERIPHERY OF THE HIGH. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR MUCH OF WESTERN AND CENTRAL ALASKA AHEAD OF THE TROUGH PREDICTED OVER THE ALEUTIANS.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO FAIRLY GOOD MODEL AGREEMENT
8-14 DAY OUTLOOK FOR JAN 05 – 11 2016
DURING THE WEEK TWO PERIOD, THE PREDICTED 500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN IS SIMILAR TO THAT DEPICTED FOR THE 6 TO 10 DAY PERIOD. SPLIT FLOW CONTINUES TO BE FORECAST OVER NORTH AMERICA AND AN ACTIVE SOUTHERN STREAM IS FORECAST ACROSS THE SOUTHERN TIER OF THE CONUS. FARTHER TO THE NORTH, AN AMPLIFIED RIDGE IN THE NORTHERN STREAM IS PREDICTED OVER WESTERN CANADA AND EASTERN ALASKA AHEAD OF A TROUGH PREDICTED OVER THE ALEUTIANS. DOWNSTREAM OF THIS RIDGE, A TROUGH IS PREDICTED OVER EASTERN CANADA. MOST MODEL SOLUTIONS RESTRICT THE SOUTHERN EXTENT OF THIS TROUGH, RESULTING IN ABOVE NORMAL HEIGHTS OVER THE NORTH CENTRAL AND NORTHEASTERN CONUS. HOWEVER, TELECONNECTIONS FROM THE POSITIVE HEIGHT ANOMALY CENTER ASSOCIATED WITH THE UPSTREAM RIDGE PREDICTED OVER WESTERN CANADA FAVORS A DEEPER TROUGH OVER EASTERN NORTH AMERICA. THIS DISAGREEMENT BETWEEN DYNAMICAL AND STATISTICAL GUIDANCE LEADS TO A LOWER CONFIDENCE FORECAST FOR THE WEEK TWO PERIOD. [Editors’s Note: This is important for East Coast Weather. Typically this sort of issue gets resolved quickly so the 8- 14 day graphics in this article will auto-update and reflect the resolution of this but the text here does not auto-updated.] THE WEEK TWO 500-HPA MANUAL HEIGHT BLEND IS BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS AND SLIGHTLY FAVORS THE 0Z ECMWF ENSEMBLE MEAN.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR ALASKA IN ASSOCIATION WITH A RIDGE FORECAST OVER WESTERN CANADA. TELECONNECTIONS FROM THE PREDICTED POSITIVE HEIGHT ANOMALY CENTER STRONGLY FAVORS BELOW NORMAL TEMPERATURES FOR THE NORTHWESTERN AND CENTRAL CONUS. HOWEVER, GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE ECMWF ENSEMBLES GENERALLY DEPICT WEAKER PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR THESE REGIONS. THE OFFICIAL MANUAL FORECAST REPRESENTS A COMPROMISE, WITH A BROAD AREA OF FAVORED BELOW NORMAL TEMPERATURES INDICATED FROM THE SOUTHERN HIGH PLAINS TO THE NORTHWEST CONUS. FARTHER TO THE EAST, BIAS CORRECTED TEMPERATURES FROM THE ECMWF ENSEMBLES AND GEFS REFORECAST GUIDANCE FAVOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE EASTERN CONUS. HOWEVER, ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES WERE KEPT WEAK AS STATISTICAL GUIDANCE FAVORS A COLDER PATTERN. THERE ARE ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR THE SOUTHERN TIER OF THE CONUS DUE TO A PREDICTED ACTIVE SOUTHERN STREAM. CONVERSELY, BELOW MEDIAN PRECIPITATION IS FAVORED FOR THE NORTHERN CONUS TO THE NORTH OF THE PREDICTED MEAN STORM TRACK. ABOVE MEDIAN PRECIPITATION IS LIKELY FOR MUCH OF WESTERN AND SOUTHERN ALASKA AHEAD OF A TROUGH PREDICTED OVER THE ALEUTIANS. BELOW MEDIAN PRECIPITATION IS FAVORED FOR PARTS OF NORTHEASTERN ALASKA IN ASSOCIATED WITH PREDICTED RIDGING.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO LARGE DIFFERENCES BETWEEN DYNAMICAL AND STATISTICAL GUIDANCE.
Some might find this analysis interesting as the organization which prepares it looks at things from a very detailed perspective and their analysis provides a lot of information on the history and evolution of this El Nino.
Analogs to Current Conditions
Now let us take a detailed look at the “Analogs” which NOAA provides related to the 5 day period centered on 3 days ago and the 7 day period centered on 4 days ago. “Analog” means that the weather pattern then resembles the recent weather pattern and was used in some way to predict the 6 – 14 day Outlook.
Here are today’s analogs in chronological order although this information is also available with the analog dates listed by the level of correlation. I find the chronological order easier for me to work with. There is a second set of analogs associated with the outlook but I have not been analyzing this second set of information. This first set applies to the 5 and 7 day observed pattern prior to today. The second set which I am not using relates to the forecast outlook 6 – 10 days out to similar patterns that have occurred in the past during the dates covered by the 6 – 10 Day Outlook. That may also be useful information but they put this set of analogs in the discussion with the other set available by a link so I am assuming that this set of analogs is the most meaningful.
Analog Centered Day | ENSO Phase | PDO | AMO | Other Comments |
Jan 2, 1990 | Neutral | – | – | |
Jan 3, 1990 | Neutral | – | – | |
Jan 9, 1991 | Neutral | – | – | |
Jan 10, 1991 | Neutral | – | – | |
Dec 7, 1998 | La Nina | – | + | Strong La Nina following 1997/1998 Super El Nino |
Dec 8, 2001 | Neutral | – | + | |
Dec 13, 2001 | Neutral | – | + | |
Jan 1, 2006 | Neutral | + | + | |
Dec 26. 2007 | El Nino | – | + | Tail end of that El Nino |
One thing that jumped out at me right away was the fairly wide spread among the analogs from December 7 to January 10 which is almost five weeks which may suggest a some doubt re the temperature forecast or simply the transition from Fall type weather to true Winter weather in different parts of the U.S. There are this time just one El Nino Analog and one strong La Nina Analog and seven ENSO Neutral Analogs so this does not suggest that El Nino is a major factor in our weather over the next 6 – 14 Days but we know that we are in a strong El Nino. The prevalence of PDO- in the analogs when we know the PDO is recording as being positive also suggests that our weather patterns are not fully consistent with what we would expect with a powerful El Nino during PDO+. The phases of the ocean cycles point to McCabe Condition B and D which are opposites. 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.
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.
With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not as easily interpreted. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.
El Ninos | La Ninas | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Start | Finish | Max ONI | PDO | AMO | Start | Finish | Max ONI | PDO | AMO | |
DJF 1950 | J FM 1951 | -1.4 | – | N | ||||||
T | JJA 1951 | DJF 1952 | 0.9 | – | + | |||||
DJF 1953 | DJF 1954 | 0.8 | – | + | AMJ 1954 | AMJ 1956 | -1.6 | – | + | |
M | MAM 1957 | JJA 1958 | 1.7 | + | – | |||||
M | SON 1958 | JFM 1959 | 0.6 | + | – | |||||
M | JJA 1963 | JFM 1964 | 1.2 | – | – | AMJ 1964 | DJF 1965 | -0.8 | – | – |
M | MJJ 1965 | MAM 1966 | 1.8 | – | – | NDJ 1967 | MAM 1968 | -0.8 | – | – |
M | OND 1968 | MJJ 1969 | 1.0 | – | – | |||||
T | JAS 1969 | DJF 1970 | 0.8 | N | – | JJA 1970 | DJF 1972 | -1.3 | – | – |
T | AMJ 1972 | FMA 1973 | 2.0 | – | – | MJJ 1973 | JJA 1974 | -1.9 | – | – |
SON 1974 | FMA 1976 | -1.6 | – | – | ||||||
T | ASO 1976 | JFM 1977 | 0.8 | + | – | |||||
M | ASO 1977 | DJF 1978 | 0.8 | N | – | |||||
M | SON 1979 | JFM 1980 | 0.6 | + | – | |||||
T | MAM 1982 | MJJ 1983 | 2.1 | + | – | SON 1984 | MJJ 1985 | -1.1 | + | – |
M | ASO 1986 | JFM 1988 | 1.6 | + | – | AMJ 1988 | AMJ 1989 | -1.8 | – | – |
M | MJJ 1991 | JJA 1992 | 1.6 | + | – | |||||
M | SON 1994 | FMA 1995 | 1.0 | – | – | JAS 1995 | FMA 1996 | -1.0 | + | + |
T | AMJ 1997 | AMJ 1998 | 2.3 | + | + | JJA 1998 | FMA 2001 | -1.6 | – | + |
M | MJJ 2002 | JFM 2003 | 1.3 | + | N | |||||
M | JJA 2004 | MAM 2005 | 0.7 | + | + | |||||
T | ASO 2006 | DJF 2007 | 1.0 | – | + | JAS 2007 | MJJ 2008 | -1.4 | – | + |
M | JJA 2009 | MAM 2010 | 1.3 | N | + | JJA 2010 | MAM 2011 | -1.4 | + | + |
JAS 2011 | FMA 2012 | -0.9 | – | + | ||||||
T | MAM 2015 | NA | 1.0 | + | N |
Progress of the Warm Event
Let us start with the SOI.
Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day moving/running average and the third is the 90 day moving/running average.
Date | Current Reading | 30-Day Average | 90 Day Average |
Dec 22 | -4.2 | -14.46 | -13.28 |
Dec 23 | +6.8 | -11.63 | -12.93 |
Dec 24 | +30.7 | -10.70 | -12.25 |
Dec 25 | +28.2 | -9.93 | -11.57 |
Dec 26 | +12.9 | -9.37 | -11.23 |
Dec 27 | -2.8 | -9.06 | -11.00 |
Dec 28 | -23.2 | -9.08 | -11.19 |
The Inactive Phase of the MJO has played out and has shifted to the Active Phase so we stopped at least temporarily seeing negative readings and now are seeing some positive La Nina-ish readings although the reading today is a strong El Nino reading. One day is not a meaningful sample. The 30-day average, which is the most widely used measure, on December 28 is reported at -9.08 which is considerable weaker than last week but still a reading that is associated with an El Nino (usually required to be more negative than -8.0 but some consider -6.0 value good enough). The 90-day average has also gotten weaker but remains in El Nino territory at -11.19. The SOI continues to be indicative of an El Nino Event in progress.
Low-Level Wind Anomalies
Here are the low-level wind anomalies. In October, the area from 180W to 160W was of interest and quite intense. There then was an area of interest at 160W which also was quite intense. Now, calm appears to prevail but that likely will change as the MJO changes phase and becomes more active. There is a WWB (Westerly Wind Burst) at 160E to 170W so perhaps we will have Kelvin Wave #6. It is too late for it to directly contribute to the recorded strength of this El Nino but it still could have an impact on the way this El Nino interacts with the Atmosphere and could slow the demise of this El Nino by adding more warm water to the El Nino related Eastern Pacific Warm Pool.
In the below graphic, you can see how the convection pattern (really cloud tops) no longer shows the pronounced pattern that has existed for a number of months. This is especially evident to the west of the Date Line. But east of the Date Line the wet anomaly is now more robust and drifting slightly to the East which could be a precursor to more impacts on CONUS.
Let us now take a look at the progress of Kelvin Waves which are the key to the situation. The most extreme temperature anomaly colored gray in the graphic is now no longer there. We now focus on the next lower level of warm anomaly which also has exited the ONI/Nino 3.4 Measurement Area which runs from 170W to 120W. But it is now impacting Nino 3.0 and Nino 1+2. Previously (looking just a bit above the bottom of this Hovmoeller diagram) we saw a slow steady retreat to the east of the western extreme of this pattern. But then we saw some mildly warmer water further west suggesting that there may indeed be a Kelvin Wave #5 in this strange story. Due to the slow speed of eastern progression of Kelvin Waves, this is unlikely to impact the recorded strength of the El Nino this winter but could impact the convection pattern in the Pacific and also extend the life of this El Nino further into Spring and might impact the next stage of the ENSO Cycle as the retreat to the west of the warm pool that has built up in the Eastern Pacific may not be able to begin its journey westward on schedule. But today the eastern movement of the warm anomaly is quite evident. This El Nino may be decaying quite rapidly.
We are now going to change the way we look at a three dimensional view of the Equator and move from the surface view to the view from the surface down. This El Nino appears to be fading slowly from west to east. The real decline will be from east to west so that may be starting but has not progressed to any large extent as yet but there are signs that it is beginning.
Current Sub-Surface Conditions
Top Graphic (Anomalies)
The above graphic showing the current situation has an upper and lower graphic. The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters.
The top graphic is still the most useful of the two and shows where 2C (anomaly) water is impacting the area in which the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to 180W which is very impressive.The 3C anomaly now extends to beyond 160W so I am viewing the 3C anomaly as encompassing essentially 100% of the Nino 3.4 Measurement Area for the ONI along the Equator but not the full area which extends five degrees latitude to the north and south of the Equator. It explains why NOAA is coming up with high ONI estimates. The 4C anomaly is now intersecting the surface only at 115W.
Bottom Graphic (Absolute Values which highlights the Thermocline)
The bottom half of the graphic may soon become more useful in terms of tracking the progress of this Warm Event as it converts to ENSO Neutral and then La Nina. It shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event. You can see that the cooler water is not yet fully making it to the surface to the east along the coast of Ecuador. In fact, the 25C Isotherm no longer reaches the surface but the 26C Isotherm does. We now will pay more attention to the 28C Isotherm as west of that temperature is where convection is more easy to occur.
TAO/TRITON GRAPHIC
Let us compare the situation as reported on October 4 to the most recent graphic. Remember each graphic has two parts the top part is the average values, the bottom part is those values expressed as an anomaly compared to the expected values for that date. Generally I am mainly discussing the bottom of the pairs of graphics namely the anomalies
First the October 4 version which I am providing for purposes of comparison.
And then the December 14 version which I “flash froze” to stop it from updating.
And then the current version of the TAO/TRITON Graphic. It is a bit less intense than on December 14. The 3.5C anomaly is no longer visible. But in general, the situation has not changed much over the past two weeks except to deamplify slightly.
———————————————– | A | B | C | D | E | —————- |
The Easterlies are diminished (except east of 110W) but now show as Easterlies almost everywhere (top graphic) which is different than on October 4, 2015 when the anomalies were so strong that west of 150W they showed as having been converted into Westerlies. That could be an indication that the conditions for maintaining this El Nino are slowly changing.
I calculate the ONI each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W ONI measuring area into five subregions (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 28 in the afternoon working from the December 27 TAO/TRITON report, this is what I calculated.
Anomaly Segment | Estimated Anomaly |
A. 170W to 160W | 2.3 |
B. 160W to 150W | 2.9 |
C. 150W to 140W | 2.8 |
D. 140W to 130W | 2.7 |
E. 130W to 120W | 2.9 |
Total | 13.6 |
Total divided by five subregions i.e. the ONI | (13.6)/5 = 2.7 |
My estimate of the daily Nino 3.4 ONI after rounding has decreased to 2.7. NOAA has today reported the weekly ONI as being 2.7 which is significantly lower than last week. Nino 4.0 is reported as being 1.6.which is a bit lower than last week. Nino 3.0 is being reported as 2.7 also significantly lower than last week. I believe it peaked at 3.7 during the El Nino of 1997/1998. This is one of many reasons for thinking that this El Nino is shifted to the west to some extent and is clearly significantly weaker than the 1997/1998 Super El Nino. The action which I think is most important to track right now is in Nino 1+2 which is now reported as being 2.1 which is a quite a bit lower than last week. The issue remains the extent to which warm water off of Ecuador and Peru impacts CONUS weather. I think it has very little impact except from the tropical storms that move up the west coast of Central America and sometimes contribute moisture to the circulation over CONUS. These part of an El Nino seems to have come to an end. Most El Ninos decay from east to west so it will be observed most clearly first in Nino 1+2 and we should see that process staring very soon now.
This is summarized in the following NOAA Table. I am only showing the currently issued version as the prior values are shown in the small graphics on the right with this graphic. They are all showing a decline.
One wonders about these calculations as they appear to not be related to the “adjusted” version of the NOAA forecast model which was discussed recently. So it is not clear to me how this El Nino will be officially recorded. September-October-November has now been recorded as having an ONI of 2.0. In the NINO value historical graphics on the right, eyeballing it you might conclude that the three months were observed as being 2.3, 2.4, and 2.5. So the impact of adjusting these observed values to what is considered “adjusted” is not obvious to me. If 2.3, 2.4, and 2.5 when averaged and adjusted by NOAA come to 2.0 how should we interpret the unadjusted weekly value of 2.7? To me (and some other knowledgeable folks) it is meaningless but I dutifully report it. One expects that OND value will be higher than 2.0. The full history of the ONI readings can be found here.
Although I discussed the Kelvin Waves earlier, now seems to be the best place to show the evolution of the subsurface temperatures.
I do not see much change week to week as watching an El Nino evolve is like watching paint dry. The cool anomaly in the west under the warm anomaly is slowly creeping east undercutting the warm anomaly and now is now over to 125W. This sequence of four or five Kelvin Waves has made for a complex pattern. We still see at 100W perhaps a trend for cooler water to rise closer to the surface. In another graphic, which I presented earlier, you can see a cool anomaly at greater depth moving up. It is now at 350 meters which does not show up in this graphic.
SST Surface Anomaly Hovmoeller
Here is another way of looking at it: Unlike the Upper Ocean Heat Anomaly Hovmoeller (I call it the Kelvin Wave Hovmoeller) which takes an average down to 300 meters, this just measures the surface temperature anomaly. It is the surface that interacts with the atmosphere. 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. Nevertheless this Hovmoeller provides a good way to visually see the evolution of this El Nino and later track its demise. One can easily see the historical evolution of this El Nino and also the current “hot spots” that are showing up and leading to the very high ONI readings. But one can also see the western edge of the warm anomaly starting to shift to the East. You can see at the very bottom of this graphic, which shows the most recent readings, the easing of the extreme temperature anomalies in the Nino 3.4 Measurement area (see the scale on the right: red is less warm than dark red) namely 170W to 120W. That explains the slight reduction in NOAA ONI estimate. That is likely to continue to be the trend.
Here is the same graphic frozen (it will not continue to auto-update) with my interpretation of the creation and now decline of this historic El Nino.
It is a full year picture of this historic event but of course incomplete as the demise has just begun.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
Below are snapshots of 30 Day temperature and precipitation departures over the life of this El Nino. The end of the 30 day period is shown in the graphic. It is a way of seeing how the impacts of this El Nino of unfolded.
The major change since last week (which is shown but remember this is a 30 day average) is deamplication of the La Nina pattern in the Southwest and the start of the El Nino impacts in the Southeast. We will now see (and actually have seen this past weekend but not yet shown in this graphic) the spread of El Nino impacts to more of the Southwest. The wetness in the Great Plains is quite interesting. We will soon see the warm anomaly in the East fade.
I realize this is a lot of graphics but one needs to look at the history of an event to assess it. As you can see, so far we are not having expect El Nino Impacts in CONUS.
El Nino in the News
Comparison of this with other strong El Ninos
Putting it all Together.
The subsurface reservoir of warm water in the Eastern Pacific has reached its maximum and is now beginning to discharge. This would have occurred earlier if not for Kelvin Waves #4 and possibly #5. This El Nino has peaked in intensity and is in decline.
The impacts in the Indian Ocean seem to have peaked and are moderating. Same goes for the Western Pacific. Now the focus shifts to North and South America. NOAA and JAMSTEC have issued forecasts but there does not seem to be an obvious match to any prior El Nino in the modern era which to me means there is no model to use to predict impacts. But this is a very strong El Nino. The best bet is that it will behave more like the two strong El Ninos which occurred with PDO+ than the one that occurred with PDO-. This would suggest that both NOAA and JAMSTEC generally are correct although their forecasts differ slightly. The three geogrpahic areas I used to categorize regional impacts are all likely to be wetter than normal/climatology. But the Southeast is not likely to be as wet as was the case with the 1997/1998 El Nino. So far, the impacts to CONUS appear to be shifted further north than usual for an El Nino. That may change as the winter unfolds but that is by no means certain.
We are beginning to speculate on the winter of 2016/2017 which now according to the models seems increasingly likely to be a La Nina. One thing that is fairly certain for the U.S.based on historical patterns is that compared to this winter the following winter is likely to be:
- warmer in the south and less warm in the north and
- more dry in the south and less dry in the north.
The below is the recently updated CPC/IRI forecast which is not much different from the Early December forecast. You can see the rapid shift away from El Nino that is now predicted starting in AMJ and really showing up in MJJ 2016 i.e. late Spring early Summer 2016. We also now see the rise in the probabilities for La Nina heading into next Winter.
It is possible the models 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 year 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.
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.
TABLE OF CONTENTS FOR PART II OF THIS REPORT The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page II where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
A. Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks (Usefully bookmarked as it provides automatically updated current weather conditions and forecasts at all times. It does not replace local forecasts but does provide U.S. national and regional forecasts and, with less detail, international forecasts)
B. Factors Impacting the Outlook
1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)
2. Medium Frequency Cycles such as ENSO and IOD
3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.
C. Computer Models and Methodologies
D. Reserved for a Future Topic (Possibly Predictable Economic Impacts)
TABLE OF CONTENTS FOR PART III OF THIS REPORT – GLOBAL WARMING WHICH SOME CALL CLIMATE CHANGE. The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page III where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
D2. Climate Impacts of Global Warming
D3. Economic Impacts of Global Warming
D4. Reports from Around the World on Impacts of Global Warming