Written by Sig Silber
Re the Monsoon: Break – Surge – Break: Re 6 to 14 Day Outlook: Don’t Count on it.
NOAA is assigning a low probability to the 6 – 14 Day Forecast due to “FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO A PREDICTED LOW AMPLITUDE PATTERN AND CONFLICTING / WEAK SIGNALS AMONG THE SURFACE TOOLS.” Another way of putting that is that it is hard to predict weather when there is none. But we believe the real problem is the inability of the models to deal with a confusing situation most likely related to the time of year and the rapid change in conditions along the Equator. The Southwest Monsoon has been going through rapid changes. Earlier this past week, we had a Break (reduction in activity) and we may now be in the final days of a Surge and the forecast is for another probably short Break. it is a bit unusual to have these rapid swings. It may be that the Monsoon this summer requires favorable conditions to overcome certain negative factors.
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The Seasonal Outlook Update Report was published on Saturday July 22 and can be accessed here. 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.
Forecast Summary with a Focus on the Southwest Monsoon.
| Temperature | Precipitation | |
| 6 – 10 Day |  |  |
| 8 – 14 Day |  |  |
What does it mean for Eclipse Viewing?
Credit: Michael Zeiler, www.GreatAmericanEclipse.com
A. Focus on Alaska and CONUS (all U.S.. except Hawaii)
First Let us focus on the Current (Right Now to 5 Days Out) Weather Situation.
Water Vapor.
This view of the past 24 hours provides a lot of insight as to what is happening.
Below is the same graphic as above but without the animation to show the current situation with respect to water vapor imagery for North America. It also covers more of CONUS.
Looking at the current activity of the Jet Stream.
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 especially in the winter The sub-Jet Stream 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 with the cutoff lows being further south than the Jet Stream. Some basic information on how to interpret the impact of jet streams on weather can be found here and here.
This graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.
You can convert the above graphic in to a flexible forecasting tool by clicking here. One can obtain views of different geographical areas by clicking here.
Notice Hurricane Gert in the above graphic.
60 Hour Forecast.
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.
Tropical Activity
When there is activity and I have not provided the specific links to the storm of “immediate” interest, one can obtain that information at this link. At this point in time, no tropical events are expected to impact CONUS. If that changes, we will provide an update.
Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 6. The Day 3 forecast can be found here. I used to present the Day 3 with a link to Day 6 but showing Day 6 may be more useful.
Now looking at the Day 5 Jet Stream Forecast.
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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.
You can enlarge the below daily (days 3 – 7) weather maps for CONUS by clicking on Day 3 or Day 4 or Day 5 or Day 6 or Day 7. These maps auto-update so whenever you click on them they will be forecast maps for the number of days in the future shown.
Here is the seven-day cumulative 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.Thickness of 600 or more suggests very intensely heat and fire danger.
Four- Week 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
I am starting with a summary of small images of the three short-term maps. This summary provides a quick look. I could have made it so you could click and enlarge the small images but for the moment I prefer that you go past the summary for the larger versions because if I set up such links, the chances increase that you will not back out of the link properly and get lost. For most people the summary with the small images will be sufficient. Following the graphic with the three small images, you can find the larger maps and a discussion and for reference purposes I then also provide the forecast map for the current or soon to be current full month and the three-month forecast map. These are issued and updated less frequently than the first three maps shown.
| 6 to 10 Days | 8 to 14 Days | Weeks 3 and 4 |
| |  |
| The above shows the progression of forecasts from six days out through four weeks out. Larger maps with discussion appear below. But this set of three maps paints a pretty good picture of what the forecast is. | ||
Now the larger maps followed by a discussion that describes what is happening and any inconsistences that I see.
6 – 10 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on August 14, 2017 was 2 out of 5)
8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on August 14, 2017 was 2 out of 5).
Looking further out.
| August 20 to August 28 | August 26 to September 8 |
Days 6 – 10: Alaska and CONUS Northwest extending a bit south to the border with Mexico and also into the Central Plains is Cool or EC. Everything else is warm. | For CONUS, the Middle Mississippi River and west through the Central Plains is cool. The far west, New England, Upper Great Lakes area is warm. Most of Alaska is warm but Southern Alaska and he Panhandle is EC. The transition to the pattern shown in the Week 3 – 4 Forecast from the pattern shown in the 8-14 Day forecast appears to be feasible. |
| Week 2: As the period evolves, there is not much change. But the Southern Tier warm anomaly closes the cool gap in the Southwest. | |
| Remember the Week 3-4 Experimental Outlook was issued last Friday and I am looking at the 6 – 10 and 8 – 14 day forecasts issued today i.e. Monday. So that explains the overlap of dates. Remember that the Week 3 – 4 Forecast covers two weeks so it can appear to not mesh perfectly but actually do so over the two-week period. For all three time periods, in between the cool and warm anomalies it is usually EC i.e. the boundary is usually not sharp. | |
Reference Forecasts Full Month and Three Months.
Below is the Temperature Outlook for the month shown in the Legend. This map is first issued on the Third Thursday of the Month for the following month and then updated on the last day of the month. The 6 – 10 day and 8 – 14 Day update daily and the Week 3/4 Map Updates every Friday so usually these are more up-to-date. Note that the three maps shown at the beginning of this discussion on temperature may cover a slightly different time period since they update as the month progresses and the map below covers a particular month shown in the Legend. It is useful if one wants to understand how that month is forecast to play out.
Here is the Temperature Outlook issued on the date and for the three-month period shown in the Map Legend. Again this is provided for reference only. It is the same map that is included in our Saturday night report that follows the NOAA third Thursday of the month Seasonal Outlook Update. It provides a longer time frame than the above maps. It uses a totally different methodology as it is not possible to use the dynamical models to project out three months. The dynamical models work by figuring out how the current conditions will evolve over a fairly short period of time. To look out three months or longer the approach is more statistical using the forecasted ENSO Phase and Climate Trends.
Now – Precipitation
I am starting with a summary of small images of the three short-term maps. This summary provides a quick look. I could have made it so you could click and enlarge the small images but for the moment I prefer that you go past the summary for the larger versions because if I set up such links, the chances increase that you will not back out of the link properly and get lost. For most people, the summary with the small images will be sufficient. Following the graphic with the three small images, you can find the larger maps and a discussion and for reference purposes I then also provide the forecast map for the current or soon to be current full month and the three-month forecast map. These are issued and updated less frequently than the first three maps shown.
| 6 to 10 Day | 8 to 14 Day | Weeks 3 and 4 |
| |  |
| The above shows the progression of forecasts from six days out through four weeks out. Larger maps with discussion appear below. But this set of three maps paints a pretty good picture of what the forecast is. | ||
Now the larger maps followed by a discussion that describes what is happening and any inconsistencies that I see.
6 – 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on August 14, 2017 was 2 out of 5)
8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on August 14, 2017 was 2 out of 5)
Looking further out.
.
| August 20 to August 28 | August 26 to September 8, 2017 |
Days 6 -10: CONUS west and Texas are mostly dry with California and points to the northeast mostly Normal. Alaska is wet in the east including the Panhandle and dry to the west. CONUS in the areas not yet described is mostly wet but bifurcated with a Normal to dry swath running SE to NW | For CONUS, the Northwest is dry. A wet anomaly extends from North Central down and slightly southwest to Texas and then east to the East Coast but not including South Florida. Where this pattern bends is where the forecast calls for a cool anomaly. Western Alaska is wet. The transition to the pattern shown in the Week 3 – 4 Forecast from the pattern shown in the 8-14 Day forecast appears to be feasible. |
Week 2: As the period evolves the Normal to Dry swath fills in wet except in the Middle Atlantic States and part of New England. | |
Remember the Week 3-4 Experimental Outlook was issued last Friday and I am looking at the 6 – 10 and 8 – 14 day forecasts issued today i.e. Monday. So that explains the overlap of dates. Remember that the Week 3 – 4 Forecast covers two weeks so it can appear to not mesh perfectly but actually do so over the two-week period. In between the dry and wet anomalies, it is usually EC i.e. the boundary is usually not sharp. | |
Reference Forecasts Full Month and Three Months.
Below is the Precipitation Outlook for the month shown in the Legend. This map is first issued on the Third Thursday of the Month for the following month and then updated on the last day of the month. The 6 – 10 day and 8 – 14 Day update daily and the Week 3/4 Map Updates every Friday so usually these are more up to date. Note that the three maps shown at the beginning of this discussion about precipitation may cover a slightly different time period since they update as the month progresses and the map below covers a particular month shown in the Legend. It is useful if one wants to understand how that month is forecast to play out.
Below is the Precipitation Outlook issued on the date and for the three-month period shown in the Map Legend. Again, this is provided for reference only. It is the same map that is included in our Saturday night report that follows the NOAA third Thursday of the month Seasonal Outlook Update. It provides a longer time frame than the above maps. It uses a totally different methodology as it is not possible to use the dynamical models to project out three months. The dynamical models work by figuring out how the current conditions will evolve over a fairly short period of time. To look out three months or longer, the approach is more statistical using the forecasted ENSO Phase and Climate Trends.
Here is the NOAA discussion released today August 14. 2017
6-10 DAY OUTLOOK FOR AUG 20 – 24 2017
TODAY’S DYNAMICAL MODELS ARE IN FAIR AGREEMENT ON THE PREDICTED MID-TROPOSPHERIC FLOW PATTERN. A RELATIVELY LOW AMPLITUDE PATTERN IS DEPICTED ACROSS MUCH OF THE FORECAST DOMAIN. TROUGHS ARE FORECAST OVER THE WEST COAST OF THE CONUS AS WELL AS OVER NORTHERN ALASKA EXTENDING TO PARTS OF THE BERING SEA AND ALEUTIANS. MOSTLY ZONAL FLOW IS INDICATED ACROSS THE NORTHERN TIER OF THE CONUS FROM THE NORTHERN PLAINS TO THE NORTHEAST. CLIMATOLOGICAL SUBTROPICAL RIDGING IS PREDICTED OVER THE SOUTH-CENTRAL CONUS. A WEAKNESS IN THE SUBTROPICAL RIDGE IS FORECAST OVER PARTS OF THE SOUTHEASTERN CONUS. TODAY’S MANUAL 500-HPA HEIGHT BLEND IS BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS FROM THE CANADIAN, GEFS, AND ECMWF. THE RESULTING 500-HPA HEIGHT ANOMALY FIELD SHOWS NEAR TO SLIGHTLY BELOW NORMAL HEIGHTS FOR MUCH OF THE WEST-CENTRAL CONUS, FLORIDA AND THE EASTERN GULF COAST, AND MOST OF ALASKA. NEAR TO ABOVE NORMAL HEIGHTS ARE INDICATED FOR THE NORTHEASTERN CONUS, PARTS OF THE SOUTHERN PLAINS, PARTS OF THE WEST COAST, AND THE EASTERN ALEUTIANS/ALASKA PENINSULA.
ODDS OF BELOW NORMAL TEMPERATURES ARE ELEVATED OVER MOST OF ALASKA AS WELL AS PARTS OF THE NORTHWESTERN CONUS DUE TO TROUGHS NEAR THESE REGIONS. MEAN SOUTHERLY/SOUTHWESTERLY LOW LEVEL FLOW AROUND A SURFACE HIGH OVER THE MID ATLANTIC LEADS TO INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES FOR THE GREAT LAKES AND NORTHEAST. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE SOUTHERN PLAINS DUE TO SUBTROPICAL RIDGING. ENHANCED ODDS FOR ABOVE NORMAL TEMPERATURES ARE INDICATED FOR PARTS OF THE SOUTHEASTERN CONUS TO THE SOUTH OF AN ANTICIPATED MEAN FRONTAL BOUNDARY. PROBABILITIES FOR ABOVE NORMAL TEMPERATURES ARE ELEVATED FOR PARTS OF THE ALEUTIANS DUE TO DYNAMICAL MODEL GUIDANCE AS WELL AS ANTICIPATED ABOVE NORMAL SSTS IN ADJACENT WATERS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR NORTHERN CALIFORNIA TO THE SOUTH OF AN ANTICIPATED FRONTAL BOUNDARY OVER THE NORTHWESTERN CONUS.
ABOVE NORMAL PRECIPITATION IS LIKELY FOR PARTS OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY, GREAT LAKES, AND EASTERN PORTIONS OF THE NORTHERN AND CENTRAL PLAINS DUE TO MOIST SOUTHERLY/SOUTHWESTERLY FLOW AND THE PROXIMITY OF AN ANTICIPATED MEAN FRONTAL BOUNDARY. BELOW NORMAL PRECIPITATION IS FAVORED FOR THE SOUTHERN PLAINS DUE TO SUBTROPICAL RIDGING. A POTENTIAL WEAKNESS IN THE SUBTROPICAL RIDGE LEADS TO ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR THE SOUTHEASTERN CONUS. BELOW NORMAL PRECIPITATION IS FAVORED FARTHER TO THE NORTH FOR PORTIONS OF THE MID ATLANTIC TO THE OHIO VALLEY UNDERNEATH MEAN SURFACE HIGH PRESSURE. THERE ARE INCREASED ODDS FOR ABOVE NORMAL PRECIPITATION FOR PARTS OF THE PACIFIC NORTHWEST NEAR A MEAN TROUGH. BELOW MEDIAN PRECIPITATION IS FAVORED FARTHER FROM THE TROUGH AXIS FOR PARTS OF THE NORTHERN AND CENTRAL HIGH PLAINS, CENTRAL ROCKIES, AND PARTS OF THE SOUTHWEST. HOWEVER, A SMALL AREA OF SLIGHTLY ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION IS INDICATED FOR SOUTHERN NEW MEXICO DUE TO POTENTIAL SOUTHERLY FLOW AROUND THE RIDGE PREDICTED OVER THE SOUTHERN PLAINS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FOR EASTERN MAINLAND ALASKA AND THE PANHANDLE AHEAD OF A TROUGH WHILE BELOW NORMAL PRECIPITATION IS FAVORED BEHIND THE TROUGH AXIS FOR PARTS OF SOUTHWESTERN ALASKA.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO A PREDICTED LOW AMPLITUDE PATTERN AND CONFLICTING WEAK SIGNALS AMONG THE SURFACE TOOLS.
8-14 DAY OUTLOOK FOR AUG 22 – 28 2017
DURING THE WEEK-2 PERIOD, TODAY’S MODEL SOLUTIONS GENERALLY PREDICT A CONTINUATION OF A RELATIVELY LOW AMPLITUDE PATTERN ACROSS MUCH OF THE FORECAST DOMAIN. SUBTROPICAL RIDGING IS FORECAST TO RETROGRADE SLIGHTLY TO THE SOUTHERN HIGH PLAINS/SOUTHWEST AND A WEAKNESS IN THE SUBTROPICAL RIDGE CONTINUES OVER THE SOUTHEAST. FARTHER TO THE NORTH, TROUGHS ARE FORECAST OVER THE PARTS OF THE NORTHEAST, THE WEST COAST, AS WELL AS OVER MUCH OF MAINLAND ALASKA WHILE A RIDGE IS INDICATED OVER THE WESTERN ALEUTIANS. ENSEMBLE SPREAD IS MODERATELY HIGH OVER MOST OF THE FORECAST DOMAIN. THE WEEK-2 MANUAL 500-HPA HEIGHT BLEND IS BASED ON THE ENSEMBLE MEAN SOLUTIONS SPLIT FAIRLY EVENLY AMONG THE GEFS, CANADIAN, AND ECMWF MODELS. ABOVE NORMAL HEIGHTS ARE INDICATED FOR MUCH OF THE ALEUTIANS AS WELL AS PARTS OF THE NORTHEASTERN CONUS. NEAR NORMAL HEIGHTS ARE PREDICTED ELSEWHERE ACROSS THE FORECAST DOMAIN.
SUBTROPICAL RIDGING LEADS TO INCREASED ODDS FOR ABOVE NORMAL TEMPERATURES FOR THE SOUTHWESTERN CONUS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FROM THE NORTHERN PLAINS TO THE NORTHEAST UNDERNEATH ABOVE NORMAL HEIGHTS. DYNAMICAL MODEL GUIDANCE SUPPORTS FAVORED ABOVE NORMAL TEMPERATURES FOR PARTS OF THE SOUTHEASTERN CONUS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF SOUTH-CENTRAL MAINLAND ALASKA, THE SOUTHERN ALASKA PANHANDLE, AND PARTS OF THE EXTREME NORTHWESTERN CONUS NEAR PREDICTED TROUGHS. RIDGING, ABOVE NORMAL HEIGHTS, AND ABOVE NORMAL SSTS LEAD TO INCREASED ODDS FOR ABOVE NORMAL TEMPERATURES FOR THE ALEUTIANS.
MEAN SURFACE HIGH PRESSURE LEADS TO ENHANCED PROBABILITIES FOR NEAR TO BELOW NORMAL PRECIPITATION FROM THE MID-ATLANTIC TO SOUTHERN NEW ENGLAND. ABOVE NORMAL PRECIPITATION IS FAVORED AROUND THE PERIPHERY OF THIS HIGH FROM THE SOUTHEAST TO THE UPPER MISSISSIPPI VALLEY. THERE ARE ELEVATED ODDS FOR BELOW MEDIAN PRECIPITATION FOR PARTS OF THE SOUTHERN PLAINS DUE TO SUBTROPICAL RIDGING. NEAR TO ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE PACIFIC NORTHWEST NEAR A TROUGH WHILE BELOW NORMAL PRECIPITATION IS FAVORED FARTHER FROM THE TROUGH AXIS FOR MUCH OF THE INTERMOUNTAIN WEST. THERE ARE INCREASED CHANCES FOR ABOVE NORMAL PRECIPITATION FOR NORTHEASTERN MAINLAND ALASKA AS WELL AS THE ALASKA PANHANDLE NEAR AND AHEAD OF A MEAN TROUGH. BELOW NORMAL PRECIPITATION IS FAVORED BEHIND THE TROUGH AXIS FOR SOUTHWESTERN MAINLAND ALASKA AND THE ALEUTIANS.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO A PREDICTED LOW AMPLITUDE PATTERN AND CONFLICTING / WEAK SIGNALS AMONG THE SURFACE TOOLS.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON AUGUST 17
Some might find this analysis which you need to click to read 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.
Centered Day | ENSO Phase | PDO | AMO | Other Comments |
| Aug 13, 1951 | El Nino | – | + | |
| Aug 8, 1953 | El Nino | +(t) | + | |
| Aug 15, 1964 | La Nina | – | – | |
| Aug 7, 1966 | Neutral | -(t) | – | |
| Aug 9, 1966 | Neutral | -(t) | N | |
| Aug 16, 1969 | El Nino | -(t) | -(t) | Modoki Type II |
| Aug 8, 1982 | El Nino | + | – | Modoki Type II |
| Aug 9, 1982 | El Nino | + | – | |
| Aug 4, 1992 | El Nino | + | – | Tail End of a Modoki |
| Aug 5, 1992 | El Nino | – | – | Tail End of a Modoki |
(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 August 4 to August 16 which is only 12 days which is very tight set of analogs. 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 August 10. These analogs are centered on 3 days and 4 days ago (August 10 or August 11). So the analogs could be considered to be in sync with the calendar meaning that we will be getting weather that we would normally be getting this time of the year. For more information on Analogs see discussion in the GEI Weather Page Glossary.
There are seven ENSO El Nino analogs (how is that possible?), two Neutral Analogs and one La Nina analog. The phases of the ocean cycles of the analogs are most consistent with McCabe A and B which are opposites but both suggestive of the Atlantic being in control. Elsewhere we discuss the extension westward right now of the Bermuda High which to a large extent is controlling our weather. Thus I am even less confident than NOAA about their 6 – 14 day outlook.
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.
Sometimes it is easier to work in black and white especially if you print this report so there is a black and white version from the later report by the same authors. Darker corresponds to red in the color graphic i.e. higher probability of drought.
| McCabe Condition | Main Characteristics |
| A | Very Little Drought. Southern Tier and Northern Tier from Dakotas East Wet. Some drought on East Coast. |
| B | More wet than dry but Great Plains and Northeast are dry. |
| C | Northern Tier and Mid-Atlantic Drought |
| D | Southwest Drought extending to the North and also the Great Lakes. This is the most drought-prone combination of Ocean Phases. |
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.
Looking Out Beyond Three Months.
The Monthly Seasonal Outlook Update which we published Saturday June 17 can be accessed by clicking here. It looks out 15 months for NOAA (the next month plus 14 more) and for JAMSTEC three three-month periods which right now is through February 2018. So it is a very useful reference and it gets updated each month. We will publish an Update on Saturday July 22. 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.
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 August 5, 2017
And the 30 Days ending August 12, 2017
B. Beyond Alaska and CONUS Let’s Look at the World which of Course also includes Alaska and CONUS
Forecast for Today
Additional Maps showing different weather variables can be found here.
Forecast for Day 6 (Currently Set for Day 6 but the reader can change that)
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 and 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 of the URL Box. It may require hitting it a few times depending on how deep you are into the BOM tool. Below are the current worldwide precipitation and temperature forecasts for six days out. They will auto-update and be current for Day 6 whenever you view them. If you want the forecast for a different day Click Here
Temperature
Precipitation
Looking Out a Few Months
Here is the precipitation forecast from Queensland Australia:
JAMSTEC Forecasts
One can always find the latest JAMSTEC maps by clicking this link. You will find additional maps that I do not general cover in my monthly Update Report. 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.
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.[NOAA may be having problems updating their daily SST Anomaly Report so I am working with the latest version that I have]
First the categorization of the anomalies.
| Mediterranean, Black Sea and Caspian Sea | Western Pacific | West of North America | East of North America | North Atlantic |
| The Black, Caspian and Mediterranean Seas are very warm as is the Persian Gulf. | Warm. | Warm south of Mainland Alaska Warm off Baja and in Sea of Cortez . | Warm off Nova Scotia. Western Gulf of Mexico slightly warm Hudson Bay warm | Warm |
| The Tropical Pacific | Cool east of 160 W. Slightly cool around Maritime Continent. Warm near Ecuador. | |||
| Africa | West of Australia | North, South and East of Australia | West of South America | East of South America |
Cool to the west south of 10S Slightly warm off North Africa. Warm south of Africa | Cool west and southwest | Warm to the east. Slightly warm to the north. | Cool off Peru and Ecuador | Warm 20S to 40S. Slightly cool off 20S |
The categorization of the four week change in the anomalies.
| Mediterranean, Black Sea and Caspian Sea | Western North Pacific | West of North America | East of North America | North Atlantic |
Black Sea and Caspian Sea are warming. So is Persian Gulf. | Overall intense warming. But now cooling east of Japan. Below the warming area there is at about 30N and both sides of the Dateline and area that is cooling. It extends SW to NE. | Warming in Gulf of Alaska Warming west of Baja California and in Gulf of California has changed to cooling. | Warming around Nova Scotia. Cooling off of Northeast Coast of CONUS Warming southern part of Hudson Bay | Not shown in today’s graphic. |
| The Tropical Pacific | Eastern Pacific Cooling | |||
| Africa | West of Australia | North, South and East of Australia | West of South America | East of South America |
| Gulf of Guinea cooling. | Stable | Warming around New Zealand. | Cooling off Ecuador and Chile . | Mostly stable |
This may be a good time to show the recent values to the indices most commonly used to describe the overall spacial pattern of temperatures in the (Northern Hemisphere) Pacific and the (Northern Hemisphere) Atlantic and the Dipole Pattern in the Indian Ocean.
| Most Recent Six Months of Index Values | PDO Click for full list | AMO click for full list. | Indian Ocean Dipole (Values read off graph) |
| October | -0.68 | +0.39 | -0.3 |
| November | +0.84 | +0.40 | 0.0 |
| December | +0.55 | +0.34 | -0.1 |
| January | +0.10 | +0.23 | 0.0 |
| February | +0.04 | +0.23 | +0.2 |
| March | +0.12 | +0.17 | +0.0 |
| April | +0.52 | +0.29 | +0.2 |
| May | +0.30 | +0.32 | +0.2 |
| June | +0.19 | +0.31 | 0.0 |
| July | -0.41 | +0.31 | 0.0 est. |
Switching gears, below is an analysis of projected tropical hazards and benefits over an approximately two-week period.
Now let us look at the Western Pacific in Motion.
C. Progress of ENSO
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 top part shows the actual temperatures, the bottom part shows the anomalies i.e. the deviation from normal.
| ———————————————— | A | B | C | D | E | —————– |
The below table only looks at the Equator and shows the extent of anomalies along the Equator. The ONI Measurement Area is the 50 degrees of Longitude between 170W and 120W and extends 5 degrees of Latitude North and South of the Equator so the above table is just a guide and a way of tracking the changes.The top rows show El Nino anomalies. The two rows just below that break point contribute to ENSO Neutral.
Subareas of the Anomaly | Westward Extension | Eastward Extension | Degrees of Coverage | |
Total | Portion in Nino 3.4 Measurement Area | |||
| These Rows below show the Extent of El Nino Impact on the Equator | ||||
1C to 1.5C (strong) | LAND | LAND | 0 | 0 |
| +0.5C to +1C (marginal) | LAND | LAND | 0 | 0 |
| These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator | ||||
| 0.5C or cooler Anomaly (warmish neutral) | 175E110E | 170WLAND | 1515 | 00 |
| 0C or cooler Anomaly (coolish neutral) | 170W125W | 140W110W | 3015 | 305 |
| These Rows Below Show the Extent of La Nina Impacts on the Equator. | ||||
| -0.5C or cooler Anomaly | 140W | 125W | 15 | 15 |
My Calculation of the Nino 3.4 Index
So as of Monday August 14, in the afternoon working from the August 6 TAO/TRITON report [Although the TAO/TRITON Graphic appears to update once a day, in reality it updates more frequently.], this is what I calculated.
| Anomaly Segment | Estimated Anomaly | |
| Last Week | This Week | |
| A. 170W to 160W | +0.3 | +0.2 |
| B. 160W to 150W | +0.3 | +0.1 |
| C. 150W to 140W | +0.3 | +0.1 |
| D. 140W to 130W | +0.2 | 0.0 |
| E. 130W to 120W | +0.1 | 0.0 |
| Total | +1.2 | +0.4 |
| Total divided by five i.e. the Daily Nino 3.4 Index | (+1.2)/5 = +0.2 | (+0.4)/5 = +0.1 |
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.
I had stopped showing the below graphic which is more focused on the Equator but looks down to 300 meters rather than just being the surface. But recently there has been sufficient change to warrant including this graphic. And now that we are back tracking a possible El Nino it is the graphic of choice.
Let us look in more detail at the Equatorial Water Temperatures.
We are now going to 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 This graphic provides both a summary perspective and a history (small images on the right).
.
Now for a more detailed look (there is some redundancy with the above graphic). Notice by the date of the graphic (dated August 6, 2017) that the lag in getting this information posted so the current situation may be a bit different than shown although this graphic was just updated this afternoon. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.
Below is 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 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 except along the Equator where it is adjusted every five years) and how both measures are useful for other purposes.
Here are the above graphics as a time sequence animation. You may have to click on them to get the animation going.
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 Long wave Radiation (OLR) 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. At this point there seems to be no need to show the daily preliminary values of the SOI but we can work with the 30 day and 90 day values.
The 30 Day Average on August 6 was reported as +5.02 which is an ENSO Neutral value with a cool bias i.e. close to a La Nina value. The 90 Day Average was reported at +0.46 which is an ENSO Neutral value. The change from last week is insignificant. Looking at both the 30 and 90 day averages is useful and right now both are in agreement. They seem to be tracking the Nino 3.4 Index pretty well and reflect the downturn in marginal El Nino Conditions and short-term conditions in the Western Pacific where there there had been a long string of negative values for a while. Now the 30 day average is actually positive i.e. in the direction of a La Nina but still in the Neutral Range. |
SOI = 10 X [ Pdiff – Pdiffav ]/ SD(Pdiff) where Pdiff = (average Tahiti MSLP for the month) – (average Darwin MSLP for the month), Pdiffav = long term average of Pdiff for the month in question, and SD(Pdiff) = long term standard deviation of Pdiff for the month in question. So really it is comparing the extent to which Tahiti is more cloudy than Darwin, Australia. During El Nino we expect Darwin Australia to have lower air pressure and more convection than Tahiti (Negative SOI especially lower than -7 correlates with El Nino Conditions). During La Nina we expect the Warm Pool to be further east resulting in Positive SOI values greater than +7).
To some extent it is the change in the SOI that is of most importance. The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Ocean Equatorial Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource.
Forecasting the Evolution of ENSO
The newly issued on August 10 CPC/IRI Meteorologist survey is shown on the left. The earlier July 19 IRI/CPC fully model-based report is shown on the right.
The level of confidence in the ENSO Neutral State has increased substantially.
Here is the discussion released with the graphic
ENSO Alert System Status: Not Active
Synopsis: ENSO-neutral is favored (~85% chance during Jul-Sep, decreasing to ~55% during Dec-Feb) through the Northern Hemisphere winter 2017-18.
During July, ENSO-neutral continued, as equatorial sea surface temperatures (SSTs) were near average across most of the Pacific Ocean. The latest weekly Niño SST index values were close to zero in all four Niño regions, having recently decreased from higher levels in the Niño-4 and Niño-3.4 regions. The upper-ocean heat content anomaly was near average during July, reflecting below-average temperatures along the thermocline across the central and eastern Pacific overlain by slightly above-average temperatures. Tropical convection was near average over the eastern half of the Pacific and enhanced over the western Pacific and the Maritime Continent. The lower-level trade winds were slightly enhanced near the International Date Line, and upper-level winds were near average over most of the tropical Pacific. Overall, the ocean and atmosphere system remains consistent with ENSO-neutral.
The majority of models favor ENSO-neutral through the remainder of 2017. These predictions, along with the demise of the recent Pacific warmth and continued near-average atmospheric conditions over the Pacific, lead forecasters to favor ENSO-neutral through the winter. However, some chance for El Niño (15-20%) or La Niña (25-30%) remains during the winter. Also, ENSO-neutral conditions are predicted for the upcoming peak months (August-October) of the Atlantic hurricane season. In summary, ENSO-neutral is favored (~85% chance during Jul-Sep, decreasing to ~55% during Dec-Feb) through the Northern Hemisphere winter 2017-18 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).
This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts are also updated monthly in the Forecast Forum section of CPC’s Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog.
The next ENSO Diagnostics Discussion is scheduled for 14 September 2017.
Here is the primary NOAA model.
From Tropical Tidbits.com
The above is from a legacy “frozen” NOAA system meaning the software is maintained but not updated. Notice since mid-July the collapse of Nino 3.4 values from the range of 0.5C to 0.5C down to Zero C.
Forecasts from Other Meteorological Agencies.
Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)
Discussion Issued August 16, 2017
ENSO neutral likely for the remainder of 2017
The El Niño—Southern Oscillation (ENSO) is currently neutral. All [Editor’s Note: eight] of the international climate models surveyed by the Bureau suggest the tropical Pacific Ocean is likely to stay ENSO neutral for the remainder of 2017.
Sea surface temperatures (SSTs) have cooled over much of the central tropical Pacific during the past four weeks, and are now close to the long-term average, and within the neutral range. The 30-day Southern Oscillation Index (SOI) also remains neutral, having steadied over the past three weeks. Other indicators of ENSO, such as cloudiness near the Date Line and trade winds are also at neutral levels.
The Indian Ocean Dipole (IOD) also remains neutral with consensus amongst climate models suggesting neutral conditions are likely to persist. Some models suggest positive IOD thresholds could be reached in the coming months but these values are unlikely to be sustained long enough to classify as a positive IOD event. Positive IOD events are typically associated with below average winter and spring rainfall over central and southern Australia.
Here is the JAMSTEC June 1 forecast of the Nino 3.4 values which are the most looked at index used to forecast El Nino. (the JAMSTEC website was having problems as of the time of our publication so I am not sure when this graphic will be be there and actually it is time for the August 1 Forecast and the JAMSTEC website being off the air may be an indication that they are updating their website.)
Here is the discussion that corresponds to the JAMSTEC July 1 Nino 3.4 Forecast. We will issue our analysis of the NOAA and JAMSTEC Seasonal Outlooks on Saturday July 22.
Jul. 13, 2017
Prediction from 1st Jul., 2017
ENSO forecast:
A slightly warmer-than-normal sea surface temperature is predicted for the whole tropical Pacific. This condition will persist until boreal winter. Then, it will return into a neutral state by next spring.
Indian Ocean forecast:
All ensemble members of SINTEX-F continue to predict a positive Indian Ocean Dipole [Editor’s Note: The Australian BOM disagrees see BOM graphic and discussion below] ; the ensemble mean prediction suggests that it peaks in boreal fall. In accord to the positive IOD evolution, sea level anomalies are expected to be negative (positive) in the eastern (western) tropical Indian Ocean.
Regional forecast:
On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of central Russia and central U. S. will experience a colder-than-normal condition in the boreal fall.
As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for some parts of East Africa and West Africa during the boreal fall, whereas most parts of Indonesia, Australia, eastern China, and Brazil will experience a drier condition during the boreal fall. Those are partly due to the positive Indian Ocean Dipole.
Most parts of Japan will experience moderately warmer-than-normal and drier-than-normal conditions in the boreal fall. The wind and pressure anomalies averaged in September-November suggest that Japan might be covered by an equivalent barotropic high. Those may be due to the combined effect of “the monsoon-desert mechanism” of the positive Indian Ocean Dipole and “the Silk Road pattern” along the Asian jet.
Indian Ocean IOD (It updates every two weeks)
The IOD Forecast is indirectly related to ENSO but in a complex way.
Discussion Issued August 16, 2017
Indian Ocean Dipole outlooks
The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 13 August was +0.15 °C.
Most of the climate models surveyed by the Bureau indicate that the IOD will remain neutral during spring.
It is important to understand how and where the IOD is measured.
D. Putting it all Together.
At this time there is reduced interest as to whether or not this Summer and Fall will be El Nino situations. It would seem that the chances of other than a marginal El Nino are fairly low. The more likely deviation from Neutral right now would be in the direction of a La Nina but we do not believe that there will be a sufficiently long period of La Nina Conditions for a La Nina to be declared but the La Nina Conditions will definitely impact the Boreal Winter.
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
Nothing to Report.
Weather Research in the News
Nothing to Report
Global Warming in the News
Nothing to Report
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
H. Useful Background Information
The current conditions are measured by determining the deviation of actual sea surface temperatures from seasonal norms (adjusted for Global Warming) in certain parts of the Equatorial Pacific. The below diagram shows those areas where measurements are taken.
NOAA focuses on a combined area which is all of Region Nino 3 and part of Region Nino 4 and it is called Nino 3.4. They focus on that area as they believe it provides the best correlation with future weather for the U.S. primarily the Continental U.S. not including Alaska which is abbreviated as CONUS. The historical approach of measurement of the impact of the sea surface temperature pattern on the atmosphere is called the Southern Oscillation Index (SOI) which is the difference between the atmospheric pressure at Tahiti as compared to Darwin Australia. It was convenient to do this as weather stations already existed at those two locations and it is easier to have weather stations on land than at sea. It has proven to be quite a good measure. The best information on the SOI is produced by Queensland Australia and that information can be found here. SOI is based on Atmospheric pressure as a surrogate for Convection and Subsidence. Another approach made feasible by the use of satellites is to to measure precipitation over the areas of interest and this is called the El Nino–Southern Oscillation (ENSO) Precipitation Index (ESPI). We covered that in a weekly Weather and Climate Report which can be found here. Our conclusion was that ESPI did not differentiate well between La Nina and Neutral. And there is now a newer measure not regularly used called the Multivariate ENSO Index (MEI). More information on MEI can be found here. The jury is still out on MEI and it it is not widely used.
Interaction between the MJO and ENSO
This Table is a first attempt at trying to relate the MJO to ENSO
| El Nino | La Nina | MJO Active Phase | MJO Inactive Phase | |
|---|---|---|---|---|
| Eastern Pacific Easterlies |
|
|
|
|
| Western Pacific Westerlies |
|
|
|
|
| MJO Active Phase |
|
|
| |
| MJO Inactive Phase |
|
|
|
History of ENSO Events
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 | 0.9 | – | + | JAS 2007 | MJJ 2008 | -1.4 | – | + |
| M | JJA 2009 | MAM 2010 | 1.3 | N | + | JJA 2010 | MAM 2011 | -1.3 | + | + |
| JAS 2011 | JFM 2012 | -0.9 | – | + | ||||||
| T | MAM 2015 | AMJ 2016 | 2.3 | + | N | JAS 2016 | NDJ 2016 | -0.8* | + | + |
ONI Recent History
The full history of the ONI readings can be found here. The MEI index readings can be found here.
