Written by Sig Silber
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.
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.
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. 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.
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.
Looking at the current activity of the Jet Stream.
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
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.
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 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.
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.
Day | ENSO Phase | PDO | AMO | Other Comments |
Sept 28, 1953 | El Nino | -(t) | + | |
Oct 11, 1962 | Neutral | – | + | |
Oct 12, 1962 | Neutral | – | + | |
Oct 24, 1963 | El Nino | – | – | |
Oct 30, 1975 | La Nina | – | – | Following strong 1972/73 El Nino |
Oct 19, 1979 | El Nino | + | – | Modoki Type II |
Oct 20, 1979 | El Nino | + | – | Modoki Type II |
Oct 31, 1984 | La Nina | + | – | |
Sept 30, 2005 | Neutral | -(t) | + |
(t) = a month where the Ocean Cycle Index has just changed or does change the following month.
One thing that jumped out at me right away was the spread among the analogs from 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.
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
And the 30 Days ending October 15, 2016
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
Near Term
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
Precipitation
Temperature
Looking Out a Few Months
This is the precipitation forecast from Queensland Australia.
JAMSTEC issued their Precipitation Forecast recently based on the October 1, 2016 ENSO analysis. Notice this forecast is for December 2016 through February 2017.
Here I just focused on Europe and CONUS
Here is the temperature forecast
There is a discussion that goes with it and that discussion was released today:. .
Oct. 17, 2016
Prediction from 1st Oct., 2016
ENSO forecast:
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.
Regional forecast:
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
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.
Below I show the changes over the last month in the Sea Surface Temperature (SST) anomalies.
Look at the Western Pacific in Motion.`
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.
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.
———————————————— | A | B | C | D | E | —————– |
The below table which only looks at the Equator shows the extent of anomalies along the Equator. I had split the table to show warm, neutral, and cool anomalies. The top rows showed El Nino anomalies. When there were no more El Nino anomalies along the Equator, I eliminated those rows. The two rows just below that break point contribute to ENSO Neutral and after another break, the rows are associated with La Nina conditions. I have changed the reference date to May 23, 1016.
Subareas of the Anomaly | Westward Extension | Eastward Extension | Degrees of Coverage | ||||
As of Today | May 23, 2016 | As of Today | May 23 2016 | As of Today | In Nino 3.4 | May 23, 2016 | |
These Rows Show the Extent of ENSO Neutral Impacts on the Equator | |||||||
0.5C or cooler Anomaly* | 160E | 155E | Land | 155W | 105 | 50 | 50 |
0C or cooler Anomaly | 170E | 155W | LAND | Land | 95 | 50 | 60 |
These Rows Show the Extent of the La Nina Impacts on the Equator | |||||||
-0.5C or cooler | 180W | 145W | LAND | Land | 85 | 50 | 50 |
-1C or cooler Anomaly | 170W130W | 140W | 165W120W | 105W | 15 | 15 | 35 |
-1.5C or cooler Anomaly | LAND | 135W | LAND | 120W | 0 | 0 | 0 |
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.]
Anomaly Segment | Estimated Anomaly | |
Last Week | This Week | |
A. 170W to 160W | -1.1 | -0.6 |
B. 160W to 150W | -1.1 | -0.4 |
C. 150W to 140W | -1.1 | -0.4 |
D. 140W to 130W | -0.9 | -0.6 |
E. 130W to 120W | -1.0 | -0.7 |
Total | -5.2 | -2.7 |
Total divided by five subregions i.e. the ONI | (-5.2)5 = -1.0 | (-2.7)/5 = -0.5 |
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 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 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 a comparison between Air Pressure at Tahiti and Darwin Australia is substantially correlated with the Precipitation Pattern of the entire World..
Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day moving/running average and the third is the 90 day moving/running average.
Date | Current Reading | 30-Day Average | 90 Day Average |
Oct 11 | -5.80 | +12.18 | +7.85 |
Oct 12 | -13.15 | +11.14 | +7.93 |
Oct 13 | -18.24 | +9.50 | +7.93 |
Oct 14 | -25.79 | +7.73 | +7.74 |
Oct 15 | -12.77 | +6.61 | +7.68 |
Oct 16 | +0.97 | +6.13 | +7.69 |
Oct 17 | +12.38 | +5.93 | +7.65 |
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
And now the recently updated meteorologist Consensus version
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 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
We also now have the most recent JAMSTEC October 1 ENSO forecast.
The model continues to show ENSO Neutral for the next two years.
Ocean IOD
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.
E. Relevant Recent Articles and Reports
Weather in the News
We have been covering the cyclones in the Atlantic and Pacific with a second article that is continually updated and can be found here.
Weather Research in the News
Nothing to report
Global Warming in the News
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.
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 | ASO 1977 | DJF 1978 | 0.8 | N | – | |||||
M | SON 1979 | JFM 1980 | 0.6 | + | – | |||||
T | MAM 1982 | MJJ 1983 | 2.1 | + | – | SON 1984 | MJJ 1985 | -1.1 | + | – |
M | ASO 1986 | JFM 1988 | 1.6 | + | – | AMJ 1988 | AMJ 1989 | -1.8 | – | – |
M | MJJ 1991 | JJA 1992 | 1.6 | + | – | |||||
M | SON 1994 | FMA 1995 | 1.0 | – | – | JAS 1995 | FMA 1996 | -1.0 | + | + |
T | AMJ 1997 | AMJ 1998 | 2.3 | + | + | JJA 1998 | FMA 2001 | -1.6 | – | + |
M | MJJ 2002 | JFM 2003 | 1.3 | + | N | |||||
M | JJA 2004 | MAM 2005 | 0.7 | + | + | |||||
T | ASO 2006 | DJF 2007 | 1.0 | – | + | JAS 2007 | MJJ 2008 | -1.4 | – | + |
M | JJA 2009 | MAM 2010 | 1.3 | N | + | JJA 2010 | MAM 2011 | -1.4 | + | + |
JAS 2011 | FMA 2012 | -0.9 | – | + | ||||||
T | MAM 2015 | NA | 1.0 | + | N |
ONI Recent History
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.