Written by Sig Silber
This week should be a continuation of last week and then a change in the pattern which will moderate the extreme cold being experienced along the Northern Tier of CONUS is “likely”. NOAA continues to pretend we are having a La Nina. In the News Section, I have a link to an NCAR study and the key graphic that attempts to show where the probability of intense precipitation events is likely to occur with high-end projected impacts of Global Warming. It is very interesting.
First I want to provide some context to the word “likely” as used in the paragraph above. It is not that NOAA is unconvinced that there will be a pattern change as much as the exact way it will unfold is proving to be difficult to determine as the models keep changing their analysis and refusing to converge on the forecast.
Now some housekeeping information. Working on a Glossary of Terms but right now it is only partially operational. It will be possible increasingly to look up acronyms etc by going to the GEI Weather Page Glossary. Also for those who want the forecasts beyond three months, we reported previously on the November 17 NOAA 15-Month Forecast and compared the first ten months of the NOAA Outlook with that of JAMSTEC in a special Update that you can get to by clicking here. We will of course publish a new 15 Month Update Report shortly after December 15, 2016. Remember if you leave this page to visit links provided in this article, you can return by hitting your “Back Arrow”, usually top left corner of your screen just to the left of the URL box.
A. Focus on Alaska and CONUS (all U.S. except Hawaii) – Let’s Focus on the Current (Right Now to 5 Days Out) Weather Situation.
First, this graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.
Image credit: Center for Western Weather and Water Extremes, Scripps/UCSD. More explanation can be found at Atmospheric Rivers (Click to read full Weather Underground Dr. Bob Henson article)
To turn the above into a forecasting tool click here and you will have a dashboard for a short-term forecasting model.
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.
You can enlarge the below daily (days 3 – 7) weather maps for CONUS only by clicking on Three Day or Four Day or Five Day or Day Six or Day Seven
Here is the seven-day precipitation forecast. More information is available here.
The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients. This graphic auto-updates so when you look at it you will see NOAA’s latest thinking. The speed at which these troughs and ridges travel across the nation will determine the timing of weather impacts. This graphic auto-updates I think every six hours and it changes a lot. Because “Thickness Lines” are shown by those green lines on this graphic, it is a good place to define “Thickness” and its uses. The 540 Level general signifies equal chances for snow at sea level locations. Remember that 540 relates to sea level.
The graphic below is the Eastern Pacific a 24 hr loop of recent readings. It does a good job of showing what is going on right now. When I published, this graphic was not being displayed but the website indicated that was a temporary outage.
The graphic below (which is a bit redundant with the above) updates automatically so it most likely will look different by the time you look at it as the tropical weather patterns unlike the patterns north of 30N are generally moving from east to west but right now are moving from west to east. This graphic highlights tropical activity. Unlike the above which shows recent history, the below graphic is a satellite image with the forecast of tropical events superimposed on the satellite image. There is no significant “new” tropical activity that would appear to impact CONUS forecast for the beginning of this week.
We can track tropical storms here.
Below is the current water vapor Imagery for North America.
Looking at the current activity of the Jet Stream.
First the current situation. Not all weather is controlled by the Jet Stream (which is a high altitude phenomenon) but it does play a major role in steering storm systems. The sub-Jetstream level intensity winds shown by the vectors in this graphic are also very important in understanding the impacts north and south of the Jet Stream which is the higher-speed part of the wind circulation and is shown in gray on this map. In some cases however a Low-Pressure System becomes separated or “cut off” from the Jet Stream. In that case it’s movements may be more difficult to predict until that disturbance is again recaptured by the Jet Stream. This usually is more significant for the lower half of CONUS i.e. further south than the Jet Stream.
Now looking at the 5 Day Forecast
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.
Click here to gain access to a very flexible computer graphic. You can adjust what is being displayed by clicking on “earth” adjusting the parameters and then clicking again on “earth” to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns. This amazing graphic covers North and South America. It could be included in the Worldwide weather forecast section of this report but it is useful here re understanding the wind circulation patterns.
Four- Week Outlook
I am going to show the three-month DJF Outlook (for reference purposes although I do not have a lot of confidence in it), the Updated Outlook for the single month of December, the 6 – 10 Day and 8 – 14 Day Maps and the Week 3 – 4 Experimental Outlook. I use “EC” in my discussions although NOAA sometimes uses “EC” (Equal Chances) and sometimes uses “N” (Normal) to pretty much indicate the same thing although “N” may be more definitive.
First – Temperature
Here is the Three-Month DJF Temperature Outlook issued on November 17, 2016:
Here is the Temperature Outlook for December Issued on November 30, 2016
6 – 10 Day Temperature Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
8 – 14 Day Temperature Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
Looking further out.
Now – Precipitation
Here is the three-month DJF Precipitation Outlook issued on November 17, 2016 that I do not have much confidence in.
And here is the Updated Precipitation Outlook for December Issued on November 30, 2016
6 – 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 12 was only 2 out of 5)
Looking further out.
As I view these maps on Monday December 12 (two of the five update each day and one (the Week 3 – 4 Outlook) updates every Friday, it looks like precipitation for December 18 to January 6 will begin with Alaska wet then turning mostly EC cool with parts of the Southwest dry with the dry anomaly initially extending north to the border with Canada encompassing the Rocky Mountain States and most of the rest of CONUS wet. Gradually the mid-latitude Rocky Mountain States also become wet, The pattern would then morph into one with Alaska and the Southern Tier dry (but not extending very far north) and a small part of the Northwest and an area stretching from Tennessee to New Jersey wet. The transition between December 20 – 26 and the December 24 – January 6 maps appears to be fairly abrupt but that does not mean it will not happen that way given the 3 – 4 Experimental Forecast covers a two-weak period. When discussing anomalies, “wet” means wetter than usual for this time of the year and “dry” means drier than usual for this time of the year. The graphic shows the level of probability of being different from EC.
Here is the NOAA discussion released today December 12, 2016.
6-10 DAY OUTLOOK FOR DEC 18 – 22 2016
TODAY’S MODELS EXHIBIT FAIR AGREEMENT ON THE PREDICTED 500-HPA HEIGHT PATTERN. A WEAKENING RIDGE IS PREDICTED NEAR THE ALASKA PANHANDLE. DOWNSTREAM OF THIS RIDGE, A POSITIVELY TILTED TROUGH IS PREDICTED OVER THE WESTERN CONUS. RIDGING AND ABOVE NORMAL HEIGHTS ARE FORECAST FOR THE SOUTHEASTERN CONUS. HEIGHTS ARE FORECAST TO BE BELOW NORMAL FOR MUCH OF THE HIGH LATITUDES CONSISTENT WITH A POSITIVE AO. ENSEMBLE SPREAD IS GENERALLY LOW TO MODERATE, EXCEPT NEAR THE SOUTHWESTERN CONUS AS SOME OF THE GFS AND ECMWF ENSEMBLE MEMBERS PREDICT A CUT-OFF LOW OFF THE COAST OF BAJA CALIFORNIA. THE GREATEST WEIGHT IN TODAY’S MANUAL, 500-HPA HEIGHT BLEND WAS GIVEN TO THE 0Z ECMWF ENSEMBLE MEAN SOLUTION BASED ON CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE PREDICTED PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.
BELOW NORMAL TEMPERATURES ARE FAVORED, PARTICULARLY EARLY IN THE PERIOD, ACROSS THE NORTHERN TIER OF THE CONUS AS WELL AS MUCH OF THE CENTRAL AND WESTERN CONUS UNDERNEATH PREDICTED CYCLONIC FLOW. PREDICTED ABOVE NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR THE SOUTHEASTERN CONUS. ENHANCED PROBABILITIES FOR NEAR NORMAL TEMPERATURES ARE INDICATED FOR MOST OF ALASKA DUE TO AN EXPECTED TRANSITION FROM MILDER THAN NORMAL CONDITIONS EARLY IN THE PERIOD TO COLDER THAN NORMAL TEMPERATURES LATER. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE PANHANDLE IN ASSOCIATION WITH A PREDICTED WEAKENING RIDGE.
THERE ARE ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE EASTERN CONUS AHEAD OF THE TROUGH FORECAST OVER THE CENTRAL AND WESTERN CONUS. PRECIPITATION ESTIMATES FROM THE ECMWF AND GEFS ENSEMBLE MEMBERS AS WELL AS ANALOGS FROM THE MANUAL BLEND FAVOR BELOW MEDIAN PRECIPITATION FOR MUCH OF THE CENTRAL CONUS AND PARTS OF THE SOUTHWEST. AN ENHANCED JET FORECAST OVER THE EASTERN PACIFIC LEADS TO ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE NORTHWESTERN CONUS. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR MUCH OF ALASKA CONSISTENT WITH DYNAMICAL MODEL GUIDANCE FROM THE GEFS AND ECMWF ENSEMBLE MEMBERS.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO A LIKELY PATTERN SHIFT DURING THE OUTLOOK PERIOD.
8-14 DAY OUTLOOK FOR DEC 20 – 26 2016
DURING THE 8-14 DAY PERIOD, MODELS AGREE IN PREDICTING BELOW NORMAL HEIGHTS FOR ALASKA AND MUCH OF THE HIGH LATITUDES. WEAKLY CYCLONIC FLOW IS FORECAST FARTHER TO THE SOUTH OVER MUCH OF THE CONUS. HEIGHTS ARE GENERALLY PREDICTED TO BE BELOW NORMAL OVER THE NORTHWESTERN CONUS. ABOVE NORMAL HEIGHTS ARE PREDICTED ACROSS MUCH OF THE EAST IN ASSOCIATION WITH A RIDGE FORECAST NEAR THE SOUTHEASTERN CONUS. ENSEMBLE SPREAD IS MODERATELY HIGH, PARTICULARLY OVER THE WESTERN CONUS, AND RUN TO RUN CONSISTENCY AMONG THE DETERMINISTIC GFS IS RELATIVELY POOR. DUE TO DISAGREEMENTS AMONG THE DETERMINISTIC RUNS, TODAY’S WEEK-2 MANUAL HEIGHT BLEND IS BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS.
THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF ALASKA UNDERNEATH PREDICTED BELOW NORMAL HEIGHTS. BELOW NORMAL TEMPERATURES ARE ALSO FAVORED FOR MUCH OF THE WESTERN CONUS IN ASSOCIATION WITH FORECAST CYCLONIC FLOW. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN CONUS, PARTICULARLY THE SOUTHEAST, DUE TO PREDICTED RIDGING AND ASSOCIATED ABOVE NORMAL HEIGHTS.
ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE EASTERN CONUS CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS. DYNAMICAL MODEL GUIDANCE FROM THE GEFS AND ECMWF ENSEMBLE MEMBERS SUPPORT ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR THE NORTHERN PLAINS. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE ALEUTIANS IN ASSOCIATION WITH A PREDICTED ENHANCED JET. ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION ARE ALSO INDICATED FOR THE NORTHWESTERN CONUS NORTHWARD TO SOUTHEASTERN ALASKA IN ASSOCIATION WITH PREDICTED ZONAL 500-HPA FLOW. BELOW MEDIAN PRECIPITATION IS FAVORED TO THE SOUTH OF THE ANTICIPATED MEAN STORM TRACK ACROSS PARTS OF THE SOUTHWESTERN CONUS.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO A LIKELY PATTERN SHIFT DURING THE PERIOD AS WELL AS RELATIVELY POOR AGREEMENT AMONG THE FORECAST TOOLS ACROSS PARTS OF THE FORECAST DOMAIN.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON DECEMBER 15
Some might find this analysis interesting as the organization which prepares it focuses on the Pacific Ocean and looks at things from a very detailed perspective and their analysis provides a lot of information on the history and evolution of ENSO events.
Analogs to the Outlook.
Now let us take a detailed look at the “Analogs” which NOAA provides related to the 5 day period centered on 3 days ago and the 7 day period centered on 4 days ago. “Analog” means that the weather pattern then resembles the recent weather pattern and was used in some way to predict the 6 – 14 day Outlook.
Here are today’s analogs in chronological order although this information is also available with the analog dates listed by the level of correlation. I find the chronological order easier for me to work with. There is a second set of analogs associated with the Outlook but I have not been regularly analyzing this second set of information. The first set which is what I am using today applies to the 5 and 7 day observed pattern prior to today. The second set, which I am not using, relates to the correlation of the forecasted outlook 6 – 10 days out with similar patterns that have occurred in the past during the dates covered by the 6 – 10 Day Outlook. The second set of analogs may also be useful information but they put the first set of analogs in the discussion with the second set available by a link so I am assuming that the first set of analogs is the most meaningful and I find it so.
|Nov 16, 1955||La Nina||–||+|
|Nov 17, 1955||La Nina||–||+|
|Dec 18, 1964||La Nina||–||–|
|Dec 24, 1983||Neutral||+||–||After Powerful El Nino|
|Dec 25, 1983||Neutral||+||–||After Powerful El Nino|
|Nov 28, 1995||La Nina||+||+|
|Dec 21, 1996||Neutral||N(t)||–|
|Dec 23, 1996||Neutral||N(t)||–|
|Dec 19, 2008||Neutral||–||+|
|Dec 20, 2008||Neutral||–||+|
(t) = a month where the Ocean Cycle Index has just changed or does change the following month.
One thing that jumped out at me right away was the spread among the analogs from November 16 to December 25 which is 39 days which is quite a bit a larger spread than last week. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, is about December 5. These analogs are centered on 3 days and 4 days ago (December 7 or December 8). So the analogs could be considered pretty much in sync with the calendar meaning that we will be getting weather that normally would occur at about this time of year or a few days earlier..
For more information on Analogs see discussion in the GEI Weather Page Glossary.
There are no El Nino Analogs, four La Nina Analogs and six ENSO Neutral Analogs. The phase of the ocean cycles in the analogs points strongly towards McCabe Condition D. There are some aspects of the 6 – 14 Day Forecast that are consistent with McCabe Condition D. It is a La Nina type Southwest Drought scenario.
The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. Water Planners might usefully pay attention to the low-frequency cycles such as the AMO and the PDO as the media tends to focus on the current and short-term forecasts to the exclusion of what we can reasonably anticipate over multi-decadal periods of time. One of the major reasons that I write this weather and climate column is to encourage a more long-term and World view of weather.
|McCabe Condition||Main Characteristics|
|A||Very Little Drought. Southern Tier and Northern Tier from Dakotas East Wet|
|B||More wet than dry but Great Plains Dry|
|C||Northern Tier and Mid-Atlantic Drought|
|D||Southwest Drought extending to the North and also the Great Lakes|
You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with each of the four pairs of two phases of the AMO and PDO.
Historical Anomaly Analysis
When I see the same dates showing up often I find it interesting to consult this list.
Recent CONUS Weather
This is provided mainly to see the pattern in the weather that has occurred recently.
Here is the 30 Days ending December 3, 2016
And the 30 Days ending December 10, 2016
B. Beyond Alaska and CONUS Let’s Look at the World which of Course also includes Alaska and CONUS
World Weather Forecast produced by the Australian Bureau of Meteorology. Unfortunately I do not know how to extract the control panel and embed it into my report so that you could use the tool within my report. But if you visit it Click Here you will be able to use the tool to view temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool. Return to this report by using the “Back Arrow” usually found top left corner of your screen to the left o the URL Box. It may require hitting it a few times depending on how deep you are into the BOM tool.
Although I can not display the interactive control panel in my article, I can display any of the graphics it provides so below are the current worldwide precipitation and temperature forecasts for three days out. They will auto-update and be current for Day 3 whenever you view them. If you want the forecast for a different day Click Here
Looking Out a Few Months
This is the new precipitation forecast from Queensland Australia.
But the above is based on October/November having a rapid rise in SOI which was not the case so I used the option where you can change the assumption to a relatively stable SOI and generated a second forecast.
Here is the most recent JAMSTEC three month Temperature Forecast. (We expect to get an update of this within two weeks.
And here is the most recent three month JAMSTEC Precipitation Forecast. We expect to receive an update of this within two weeks.
And then to get more focus, I extracted and enlarged an image for Europe on the left and CONUS on the right.
There is a short JAMSTEC discussion that relates the seasonal outlook to their El Nino and El Nino Modoki forecasts and this was issued on Tuesday November 22, so here it is:
Nov. 23, 2016 Prediction from 1st Nov., 2016
According to the SINTEX-F prediction, the current La Niña Modoki/La Niña state will continue until spring. [Editor’s Note: They explain what they mean by this being a Modoki rather than a true La Nina in a very long detailed explanation which focuses on the Modoki aspects of this Cool Event. We will discuss that next Monday but the simple explanation is that the cool anomaly is not well connected to the coast of South America]. That state will then start decaying and the tropical Pacific will return to a normal state by summer. The model prediction appears to be consistent so far with the observed evolution of the sea surface temperature (SST) anomalies
Indian Ocean forecast:
The negative Indian Ocean Dipole will keep decaying and disappear in winter. The Ningaloo Nino will appear off the west coast of Australia in late austral summer and persist until late austral fall.
On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of northern Brazil, Australia, and Mongolia will experience a colder-than-normal condition in the boreal winter.
According to the seasonally averaged rainfall prediction, most parts of southern China, southeastern Africa, southern Europe, and eastern/western U.S. will experience a drier condition during boreal winter, while most parts of Brazil, western Central Africa, and South Africa will experience a wetter-than-normal condition. Australia will receive above normal rainfall during austral summer. Northern parts of Japan (including Hokkaido) will be cooler and drier than normal while southern parts of Japan will generally be warmer than normal in winter. However, we note that fluctuating mid- and -high latitude climate in winter may not be captured well by the current model.
Additional forecasts from JAMSTEC including future time periods can be found at this link.
Sea Surface Temperature (SST) Departures from Normal for this Time of the Year i.e. Anomalies
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.
Below I show the changes over the last month in the Sea Surface Temperature (SST) anomalies.
Below is an analysis of projected tropical hazards and benefits over an approximately two-week period. This graphic is scheduled to update on Tuesday and I am reading the December 6, 2016 Version and looking at Week 2 of that forecast.
Look at the Western Pacific in Motion.` When I published, this graphic was not being displayed but the website indicated that was a temporary outage.
C. Progress of the Cool ENSO Event
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.
And here is the current version of the TAO/TRITON Graphic.
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.
Subareas of the Anomaly
|Westward Extension||Eastward Extension||Degrees of Coverage|
As of Today
May 23, 2016
As of Today
May 23 2016
As of Today
In Nino 3.4
Dec 12, 2016
May 23, 2016
|These Rows Show the Extent of ENSO Neutral Impacts on the Equator|
|0.5C or cooler Anomaly*|
|0C or cooler Anomaly|
|These Rows Show the Extent of the La Nina Impacts on the Equator|
|-0.5C or cooler|
|-1C or cooler Anomaly|
|-1.5C or cooler Anomaly|
I calculate the current value of the ONI index (really the value of NINO 3.4 as the ONI is not reported as a daily value) each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W Nino 3.4 measuring area into five subregions (which I have designated from west to east as A through E) with a location bar shown under the TAO/TRITON Graphic). I use a rough estimation approach to integrate what I see below and record that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions.
So as of Monday December 12, in the afternoon working from the December 11 TAO/TRITON report, this is what I calculated. [Although the TAO/TRITON Graphic appears to update once a day, in reality it updates more frequently.]
|Anomaly Segment||Estimated Anomaly|
|Last Week||This Week|
|A. 170W to 160W||+0.3||+0.3|
|B. 160W to 150W||+0.0||+0.1|
|C. 150W to 140W||-0.3||-0.1|
|D. 140W to 130W||-0.6||-0.8|
|E. 130W to 120W||-0.7||-1.0|
|Total divided by five subregions i.e. the ONI||(-1.3)5 = -0.3||(-1.5)5 = -0.3|
From Tropical Tidbits.com
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.
In recent weeks I have stopped showing the below graphic which is more focused on the Equator but looks down to 300 meters rather than just being the surface. There has until this week been almost no change from the prior week but over the last month there has been sufficient change to warrant including this graphic this week.
Let us look in more detail at the Equatorial Water Temperatures.
We are now going to change the way we look at a three-dimensional view of the Equator and move from the surface view and an average of the subsurface heat content to a more detailed view from the surface down. Notice by the date of the graphic (dated December 9, 2016) that the lag in getting this information posted so the current situation may be a bit different than shown although this graphic was updated today so it is more current than usual. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.
And now the pair of graphics that I regularly provide. The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters. At different times I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years except along the Equator where it is adjusted every five years) and how both measures are useful but for different purposes.
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.
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.
And now Let us look at the Atmosphere.
Low-Level Wind Anomalies near the Equator
Here are the low-level wind anomalies.
And now the Outgoing Longwave Radiation Anomalies which tells us where convection has been taking place.
And Now the Air Pressure which Shows up Mostly in an Index called the SOI.
This index provides an easy way to assess the location of and the relative strength of the Convection (Low Pressure) and the Subsidence (High Pressure) near the Equator. Experience shows that the extent to which the Atmospheric Air Pressure at Tahiti exceeds the Atmospheric Pressure at Darwin Australia when normalized is substantially correlated with the Precipitation Pattern of the entire World.
Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day moving/running average and the third is the 90 day moving/running average.
|Date||Current Reading||30-Day Average||90 Day Average|
The 30-day average, which is the most widely used measure, as of December 12 is reported at -0.48 which is not much changed since last week and about as close to Neutral as possible. The 90-day average at +1.75 is less La Nina-ish than last week and again solidly Neutral. Usually but not always the 90 day average changes more slowly than the 30 day average but it depends on what values drop out. The disparity between the two is one reason why we look at both. (Sustained values over +7 are usually associated with La Nina and less than -7 are usually associated with El Nino). To some extent it is the change in the SOI that is of most importance. It had been increasing but may now be stabilizing or going down. That could change but for now the SOI is not signaling a La Nina but ENSO Neutral.
The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource. November was not particularly favorable for La Nina development and most likely neither will be December in terms of the MJO.The forecasts of the MJO are all over the place and not suggesting a strong Active or Inactive Phase of the MJO any time soon.The MJO being Inactive is more favorable for La Nina than the MJO being Active. But the MJO goes back and forth from being Active, Inactive, strong and weak so it has mostly a short-term impact. It is possible that a weak Inactive Phase of the MJO might be giving this dying La Nina a little reprieve but the forecast is that this will soon change to a weak Active Phase so it is not very significant other than on a weekly basis. .
Lately, the impact has been fairly muted. But the change in the SOI recently and some other changes suggest that we are having an Active Phase of the MJO even if such is not being reported and what we have is not the MJO but something else that is impacting the cool pool in a similar way as an Active MJO would. The forecast for the MJO is updated weekly and can be found here. If the MJO is not in its Active Phase then perhaps some other pattern is impacting the SOI and also shifting the cool pool to the east. We are also having a non-split fairly strong Jet Stream which is also consistent with an Active MJO. So I am calling it a Stealth MJO.
The MJO tends to be more important when the situation is ENSO Neutral and the MJO can start the process of an El Nino getting started. It is less significant re the initiation of a La Nina but is a factor. It is surprising how weak the MJO has been for months. But it may account for what seems like a cycling of the estimate of Nino 3.4 as the cool water is blown first to the west and then to the east. This impacts the upwelling also.
Forecasting the Evolution of ENSO
Here is the November 17, 2016 fully model-based version .
The preference for La Nina conditions in NDJ was a bit less than a week earlier when the report was based mainly on a survey of meteorologist. When I see DJF, I notice that January is the middle month in the DJF three-month period. Thus it seems that January is probably the last month that the models indicated that we will have Nino 3.4 values equal to or under -0.5. When I look at the slightly higher probability for Nino 3.4 to be -0.5 or less as compared to Nino 3.4 to be in the Neutral Range, I was not blown away by the probability that we would be in La Nina condition into 2017..We were at the time this IRI/CPC report was published past mid-November so to me the story-line should then have been the imminent end of the Cool Event rather than upgrading the Status of the Cool Event
Now we have the December early-month report from CPC/IRI which I call the reading of the tea leaves in that it is based on a combination of model results and a survey of the views of meteorologists. Here is the official description:
Figure 1 is based on a consensus of CPC and IRI forecasters, in association with the official CPC/IRI ENSO Diagnostic Discussion
Recently the early month analysis has been more favorable for a la Nina than the later in the month model-based analysis.I think meteorologists like action so they prefer either El Nino or La Nina to Neutral. But the models are dispassionate about it.
Here is the discussion that was released with the graphic.
During early December 2016 the tropical Pacific SST anomaly was near -0.5C, the threshold for weak La Niña. Also, most of the atmospheric variables across the tropical Pacific have been consistent with weak La Niña conditions, although subseasonal atmospheric variability has temporarily weakened some of them [Editor’s Note: They were not there]. The upper and lower atmospheric winds have been suggestive of a strengthened Walker circulation, and the cloudiness and rainfall have also been consistent with weak La Niña conditions. The collection of ENSO prediction models indicates SSTs near the threshold of La Niña [Editor’s Note: Close only counts in horseshoes] persisting through mid-winter, then weakening to cool-neutral by later winter.These results suggest that January is about equally likely to be La Nina or Neutral. But the models and current data suggest that we are no longer in what properly would be called La Nina Conditions and an objective assessment would be taking a different tack than NOAA is taking. One wonders why they ignore even their own forecast model and why some of their data does not agree with data released by other meteorological agencies.
Here is the daily PDF and Spread Corrected version of the NOAA CFSv2 Forecast Model.
The full list of weekly values can be found here.
Forecasts from Other Meteorological Agencies.
Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)
Discussion (notice their threshold criteria are different from NOAA but also their actuals are higher than recorded by NOAA and yet Nino 3.4 is standard. So someone is incorrect OR WORSE.)
La Niña no longer likely in the coming months
The El Niño–Southern Oscillation (ENSO) in the tropical Pacific Ocean remains neutral (neither El Niño nor La Niña). Although some very weak La Niña-like patterns continue (such as cooler than normal ocean temperatures and reduced cloudiness in the central and eastern Pacific), La Niña thresholds have not been met. Climate models and current observations suggest these patterns will not persist. The likelihood of La Niña developing in the coming months is now low, and hence the Bureau’s ENSO Outlook has shifted from La Niña WATCH to INACTIVE.
The Indian Ocean Dipole (IOD) also remains neutral (neither positive nor negative), as is typical at this time of year. When ENSO and the IOD are neutral they have limited impact on Australian climate.
The climate of Australia, and other countries around the tropical Indian Ocean and western Pacific Ocean, has been strongly influenced during the second half of 2016 by both a strong negative IOD in the tropical Indian Ocean (that ended in November) and the weak La Niña-like pattern in the tropical Pacific (which has eased). This combination of climate drivers contributed to Australia observing its wettest May to September on record in 2016.
We also have the most recent JAMSTEC November 1 ENSO forecast. There should be a new version in a week or so.
The model continues to show ENSO Neutral for the next two years (after what they call a weak La Nina Modoki ends). But the potential for an El Nino has been taken out of the forecast. The JAMSTEC Discussion is shown earlier in this report.
Indian Ocean IOD (It updates every two weeks)
The IOD Forecast is indirectly related to ENSO but in a complex way.
Indian Ocean Dipole outlooks
The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 4 December was −0.02 °C.
The influence of the IOD on Australian climate is weak during the months of December to April. This is because the monsoon trough shifts south over the tropical Indian Ocean changing wind patterns, which prevents an IOD pattern from being able to form.
However, the continued presence of much warmer than average water to the north and northwest of Australia may see continued influence on Australia, including enhanced rainfall.
D. Putting it all Together.
Looks like this Cool Event is no longer even properly described as “La Nina Conditions Apply”.
Forecasting Beyond Five Years.
So in terms of long-term forecasting, none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast. The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.
E. Relevant Recent Articles and Reports
Weather in the News
It has been cold in the Northern Tier but this has been well covered (and exaggerated) in the media so I see no need to add to that discussion).
Weather Research in the News
Nothing to report.
Global Warming in the News
Extreme Precipitation Events will be Much More Frequent: Click to read this NCAR Report.
At first I found this article and graphic upsetting. The Legend was not very informative.
A quote from the PR release made it obvious to me what this was.
The researchers looked at how storms that occurred between 2000 and 2013 might change if they occurred instead in a climate that was 5 degrees Celsius (9 degrees Fahrenheit) warmer — the temperature increase expected by the end of the century if greenhouse gas emissions continue unabated.
“Continue unabated” and 5C were to me clearly an indication that this related to RCP 8.5 and indeed to the high-end estimate of the Temperature increase that would result if we followed that path of watts per square meter increase. Here and here are two links that explain the RCP system.
Then I talked to the author and he explained to me that:
We could not afford to simulate more than one future projection under the RCP 8.5 scenario since we are running our model on a 4 km grid which is computationally extremely expensive.
So although I have not confirmed it with the author, I am pretty sure the Media Dept at NCAR prepared the Press Release and the inadequate description in the Legend of the graphic.
It would be nice to have results for the more (IMO) realistic RCP of 4.5 and 6.0 but if we interpret the above graphic as what could happen in the extreme case, it is very useful. I am guessing that the percentages and shading would be less extreme but the locations would be similar.
F. Table of Contents for Page II of this Report Which Provides a lot of Background Information on Weather and Climate Science
The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page II where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)
2. Medium Frequency Cycles such as ENSO and IOD
3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.
4. Computer Models and Methodologies
5. Reserved for a Future Topic (Possibly Predictable Economic Impacts)
G. Table of Contents 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.
2. Climate Impacts of Global Warming
3. Economic Impacts of Global Warming
4. Reports from Around the World on Impacts of Global Warming
Useful Background Information
With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not as easily interpreted. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.
|El Ninos||La Ninas|
|Start||Finish||Max ONI||PDO||AMO||Start||Finish||Max ONI||PDO||AMO|
|DJF 1950||J FM 1951||-1.4||–||N|
|T||JJA 1951||DJF 1952||0.9||–||+|
|DJF 1953||DJF 1954||0.8||–||+||AMJ 1954||AMJ 1956||-1.6||–||+|
|M||MAM 1957||JJA 1958||1.7||+||–|
|M||SON 1958||JFM 1959||0.6||+||–|
|M||JJA 1963||JFM 1964||1.2||–||–||AMJ 1964||DJF 1965||-0.8||–||–|
|M||MJJ 1965||MAM 1966||1.8||–||–||NDJ 1967||MAM 1968||-0.8||–||–|
|M||OND 1968||MJJ 1969||1.0||–||–|
|T||JAS 1969||DJF 1970||0.8||N||–||JJA 1970||DJF 1972||-1.3||–||–|
|T||AMJ 1972||FMA 1973||2.0||–||–||MJJ 1973||JJA 1974||-1.9||–||–|
|SON 1974||FMA 1976||-1.6||–||–|
|T||ASO 1976||JFM 1977||0.8||+||–|
|M||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||–||+|
ONI Recent History
The Aug/Sept/Oct reading has been issued and is currently listed as -0.7. The Sep/Oct/Nov preliminary estimate is -0.8 so there would now need for there to be two more periods of -0.5 or colder for this to be eligible to be formally recorded as a La Nina. I suspect there will be one more but not two. NOAA seems to be determined to make that happen. THEIR FUNDING MAY DEPEND ON THAT.
The full history of the ONI readings can be found here. The MEI index readings can be found here.
Leave a Reply