Written by Sig Silber
First Arizona and New Mexico had some above normal precipitation for this time of the year and now the Texas Gulf Coast is receiving tropical precipitation from the Western Gulf of Mexico. Will this continue or is it just an early taste of what normally happens in July? We address that question in this report.
To avoid suspense: the Monsoon initiation was a false start. But it does suggest that temperatures in the Southwest will not challenge records in June as was the case last year. The Subtropical Ridge needs to develop further for there to be a real initiation of Monsoon Precipitation in the Southwest.
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Adding to the discussion last week on the early onset of the North American Monsoon, the prior definition of Monsoon Onset was defined in articles such as this.
INTERNATIONAL JOURNAL OF CLIMATOLOGY Int. J. Climatol. 24: 247 – 265 (2004) Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/joc.996 A METHOD FOR DEFINING MONSOON ONSET AND DEMISE IN THE SOUTHWESTERN USA ANDREW W. ELLIS,* ERINANNE M. SAFFELL and TIMOTHY W. HAWKINS Office of Climatology, Department of Geography, Arizona State University, Tempe, AZ 85287-0104, USA Received 4 March 2003 Revised 12 November 2003 Accepted 12 November 2003
A. Now we will begin with our regular approach and focus on Alaska and CONUS (all U.S.. except Hawaii).
I am starting with a summary first for temperature and then for precipitation of small images of the three short-term maps. You can click on these maps to see larger versions. The easiest way to return to this report is by using the “Back Arrow” usually found top left corner of your screen to the left of the URL Box. Larger maps are available later in the article with the discussion and analysis.
First Temperature
This shows magnitude rather than probability of being higher or lower than Normal and shows the middle day of the five day period. | It is difficult to compare this with the other maps that show deviation from climatology as we expect the north to be cooler than the south. But it does seem to be consistent with the 6 – 10 day map. | ||
Click to Enlarge | |||
Transitioning from the 6 to 10 day outlook on the left (also called Week One) to the 8 to 14 day outlook (Week Two) on the right → | |||
The pattern is fairly stagnant. But in the second week the cold air intrusion from Mexico seems to have mixed out. | |||
To the right is the week 3 and 4 Forecast. → There is a warm anomaly for Alaska. There is a warm anomaly for Eastern CONUS except South Florida which is EC. There is another warm anomaly for part of the West Coast. And there is a cool anomaly where the Early Monsoon is expected to have an impact. | ↑ |
Then Precipitation
Let’s now return our focus back on Alaska and CONUS (all U.S.. except Hawaii).
Water Vapor.
This view of the past 24 hours provides a lot of insight as to what is happening.
You can see from this animation that there has been moisture entering Texas from the Gulf of Mexico. There is also a Great Basin Low.
Tonight, Monday evening June 18, 2018, as I am looking at the above graphic, you see the recent pattern and you do not see the presence of former Hurricane Bud.
This graphic is about Atmospheric Rivers i.e. thick concentrated movements of water moisture. More explanation on Atmospheric Rivers can be found by clicking here or if you want more theoretical information by clicking here. The idea is that we have now concluded that moisture often moves via narrow but deep channels in the atmosphere (especially when the source of the moisture is over water) rather than being very spread out. This raises the potential for extreme precipitation events. You can convert this graphic into a flexible forecasting tool by clicking here. One can obtain views of different geographical areas by clicking here.
And Now the Day One and Two CONUS Forecasts
Day One CONUS Forecast | Day Two CONUS Forecast |
These graphics update and can be clicked on to enlarge but my brief comments are only applicable to what I see on Monday night prior to publishing. |
60 Hour Forecast Animation
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.
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.
What is Behind the Forecasts? Let us try to understand what NOAA is looking at when they issue these forecasts.
Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 7. The Day 3 forecast can be found here. the Day 6 Forecast can be found here. Actually all the small graphics below can be clicked on to enlarge them.
When I look at this Day 7 forecast, there is not much to discuss other than the Hawaiian High with surface central pressure of 1028 hPa. It dominates everything. I now can locate the Bermuda High but the center is off the map but the surface central pressure is at least 1024 hPa. We are into the time of the year when warming and convection become the dominant determinant of weather. It does not look like the conditions for the Sonoran Monsoon to impact the U.S. Southwest are fully in place on Day 7.
I provided this write up that provides a simple explanation on the importance of semipermanent Highs and Lows and another link that discussed possible changes in the patterns of these highs and lows which could be related to a Climate Shift (cycle) in the Pacific or Global Warming. Remember this is a forecast for Day 7. It is not the current situation.
The table below showing the Day 3, Day 4, Day 5, Day 6 and Day 7 of this graphic can be useful in thinking about how the pattern of Highs and Lows is expect to move during the week.
Looking at the current activity of the Jet Stream. The below graphics and the above graphics are very related.
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. I have not provided the ability to click to get larger images as I believe the smaller images shown are easy to read.
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.
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.
500 MB Mid-Atmosphere View
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 generally signifies equal chances for snow at sea level locations. Thickness of 600 or more suggests very intensely heat and fire danger. Sometimes Meteorologists work with the 500 mb heights which provide somewhat similar readings to the “Thickness” lines but IMO provide slightly less specific information. Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.
Here is the whole suite of similar maps for Days 3, 4, 5, 6 and repeated for Day 7. It is hard to tell but it looks more like a pattern that generates heat than precipitation.
Day 3 Above, 6 Below | Day 4 Above,7 Below | Day 5 Above. |
Here is the seven-day cumulative precipitation forecast. More information is available here.
I am showing this but it will be blank very soon. But it explains the wet western Gulf Coast
If the above goes blank, the below (which I have frozen) is close to the last report from the National Hurricane Center.
This text advisory will not vanish but will not update.
Tropical Weather Outlook NWS National Hurricane Center Miami FL 2 AM EDT Tue Jun 18 2018
Surface observations and NOAA Doppler weather radar data indicate that a surface trough associated with a low- and mid-level low pressure system has moved inland over the Texas coastal plain. Although this system is producing a widespread area of cloudiness and disorganized showers and thunderstorms, interaction with land and proximity to dry air in the mid-levels of the atmosphere should prevent a tropical cyclone forming. However, this disturbance is likely to produce additional heavy rainfall and flash flooding across portions of southern and southeastern Texas during the next few days. For more details on this disturbance and the threat for heavy rainfall, please see products issued by your local weather office and High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours…low…near 0 percent.
* Formation chance through 5 days…low…near 0 percent.
Four – Week Outlook: Looking Beyond Days 1 to 5, What is the Forecast for the Following Three + Weeks?
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
6 – 10 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on June 18, 2018 was 3 out of 5
8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on June 18, 2018 was 3 out of 5).
–
Looking further out.
Now – Precipitation
6 – 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on June 18, 2018 was 3 out of 5)
8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on June 18, 2018 was 3 out of 5)
Looking further out.
Here is the 6 – 14 Day NOAA discussion released today June 18, 2018 and the Week 3/4 discussion released Friday June 15, 2018.
6-10 DAY OUTLOOK FOR JUN 24 – 28 2018
TODAY’S MODEL SOLUTIONS ARE IN FAIR AGREEMENT ON THE OVERALL 500-HPA FLOW PATTERN OVER THE FORECAST DOMAIN. AT THE BEGINNING OF THE PERIOD, MODELS DEPICT A TROUGH OVER THE EASTERN BERING SEA EXTENDING SOUTHEASTWARD OVER THE GULF OF ALASKA. SPLIT-FLOW IS ANTICIPATED FARTHER TO THE EAST WITH RIDGES FORECAST OVER CENTRAL CANADA AS WELL AS ALONG THE WEST COAST OF THE CONUS. SHORTWAVE TROUGHS ARE FORECAST OVER THE WEST-CENTRAL AND EAST-CENTRAL CONUS WHILE A STRONGER, LONGWAVE TROUGH IS ANTICIPATED OVER EASTERN CANADA. BY THE END OF THE PERIOD, THE TROUGH OVER THE GULF OF ALASKA IS EXPECTED TO APPROACH THE NORTHWESTERN CONUS RESULTING IN A LOWERING OF HEIGHTS ALONG THE WEST COAST. MEANWHILE THE SHORTWAVE TROUGHS OVER THE WEST-CENTRAL AND EAST-CENTRAL CONUS FORECAST TO PROGRESS EASTWARD WITH TIME TOWARD THE PLAINS AND NORTHEAST. THE MEAN, MANUAL, 500-HPA HEIGHT BLEND FOR THE FIVE DAY PERIOD, BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS FROM THE GEFS AND ECMWF, DEPICTS NEAR TO ABOVE NORMAL HEIGHTS OVER THE CONUS AND NEAR TO BELOW NORMAL HEIGHTS ACROSS ALASKA.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE CONUS UNDERNEATH NEAR TO ABOVE NORMAL HEIGHTS. HOWEVER, ENHANCED PROBABILITIES OF NEAR NORMAL TEMPERATURES ARE INDICATED FOR THE PACIFIC NORTHWEST AS A TROUGH APPROACHES THE AREA BY THE END OF THE PERIOD. NEAR NORMAL TEMPERATURES ARE ALSO FAVORED FOR PARTS OF THE CENTRAL AND SOUTHERN ROCKIES AND CENTRAL AND SOUTHERN HIGH PLAINS DUE TO AN ANTICIPATED SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT. TROUGHING AND NEAR TO BELOW NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES OF BELOW NORMAL TEMPERATURES FOR MUCH OF MAINLAND ALASKA AND THE ALASKA PANHANDLE. HOWEVER, ABOVE NORMAL SSTS FAVOR ABOVE NORMAL TEMPERATURES FOR PARTS OF THE WESTERN COAST OF MAINLAND ALASKA AND FOR PARTS OF THE ALEUTIANS.
TROUGHING OVER ALASKA LEADS TO ENHANCED PROBABILITIES OF NEAR TO ABOVE NORMAL PRECIPITATION ACROSS THE STATE. BELOW NORMAL PRECIPITATION IS FAVORED FOR THE NORTHWESTERN CONUS IN ASSOCIATION WITH ANTICIPATED SURFACE HIGH PRESSURE UPSTREAM OVER THE EASTERN NORTH PACIFIC. BELOW NORMAL PRECIPITATION IS ALSO FAVORED FOR PARTS OF THE SOUTHWEST DUE TO MEAN SUBTROPICAL RIDGING CENTERED NEAR THE U.S./MEXICO BORDER. CONVERSELY, THERE ARE ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION FROM THE CENTRAL PLAINS EXTENDING TO THE NORTHEASTERN CONUS AS SHORTWAVE TROUGHS PROGRESS TROUGH THESE REGIONS. RIDGING OVER EAST-CENTRAL CANADA LEADS TO ENHANCED PROBABILITIES OF BELOW NORMAL PRECIPITATION FOR PARTS OF THE WESTERN GREAT LAKES REGION AND UPPER MISSISSIPPI VALLEY. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FOR PARTS OF THE SOUTHEASTERN CONUS DUE TO THE POTENTIAL FOR MOIST FLOW AROUND SURFACE HIGH PRESSURE CENTERED OVER THE ATLANTIC. BELOW NORMAL PRECIPITATION IS SLIGHTLY FAVORED FARTHER TO THE WEST FOR PARTS OF THE WESTERN GULF COAST REGION, CONSISTENT WITH DYNAMICAL MODEL GUIDANCE.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO FAIR MODEL AGREEMENT.
8-14 DAY OUTLOOK FOR JUN 26 – JUL 02, 2018
DURING THE WEEK-2 PERIOD, THE ENSEMBLE MEAN SOLUTIONS FROM THE GEFS, ECMWF, AND CANADIAN ALL FORECAST TROUGHS OVER THE BERING SEA AND THE NORTHWESTERN CONUS. FARTHER TO THE EAST, RIDGING AND ABOVE NORMAL HEIGHTS ARE ANTICIPATED OVER EAST-CENTRAL CANADA EXTENDING TO PARTS OF THE GREAT LAKES AND NORTHEAST. A RIDGE IS FORECAST OVER MUCH OF THE SOUTHWESTERN CONUS WHILE A WEAKNESS IN THE SUBTROPICAL RIDGE IS PREDICTED OVER PARTS OF THE SOUTHEASTERN CONUS, PARTICULARLY BY THE 0Z ECMWF ENSEMBLE MEAN. THE MANUAL, 500-HPA BLEND, WEIGHTED MOST HEAVILY TOWARD THE 0Z ECMWF ENSEMBLE MEAN, FEATURES NEAR TO ABOVE NORMAL HEIGHTS FOR THE CONUS AND NEAR TO BELOW NORMAL HEIGHTS FOR MUCH OF ALASKA.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE CONUS, UNDER NEAR TO ABOVE NORMAL 500-HPA HEIGHTS. HOWEVER, NEAR TO BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE NORTHWESTERN CONUS DUE TO A PREDICTED TROUGH. THE PREDICTED TEMPERATURE PATTERN FOR ALASKA IS SIMILAR BETWEEN THE 6-10 AND 8-14 DAY PERIODS.
PERSISTENT TROUGHING OVER THE EASTERN BERING SEA LEADS TO ENHANCED PROBABILITIES OF NEAR TO ABOVE NORMAL PRECIPITATION ACROSS ALASKA. STRONG, SURFACE HIGH PRESSURE OVER THE EASTERN NORTH PACIFIC AND ASSOCIATED NORTHERLY, LOW-LEVEL FLOW FAVOR BELOW NORMAL PRECIPITATION ACROSS THE NORTHWESTERN CONUS. THERE ARE ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION FARTHER TO THE EAST FOR PARTS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY CONSISTENT WITH DYNAMICAL MODEL GUIDANCE AND WITH TELECONNECTIONS FROM A POSITIVE HEIGHT ANOMALY CENTER ANTICIPATED OVER EASTERN CANADA. CONVERSELY, THE RIDGE FORECAST OVER EASTERN CANADA FAVORS BELOW NORMAL PRECIPITATION FOR PARTS OF THE NORTHEASTERN CONUS. SUBTROPICAL RIDGING LEADS TO FAVORED BELOW NORMAL PRECIPITATION FOR THE SOUTHERN PLAINS. A FORECAST WEAKNESS IN THE SUBTROPICAL RIDGE FAVORS ABOVE NORMAL PRECIPITATION ACROSS THE SOUTHEASTERN CONUS.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO FAIR MODEL AGREEMENT.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON JUNE 21.
Week 3-4 Forecast Discussion Valid Sat Jun 30 2018-Fri Jul 13 2018
The MJO is in an inactive state this week although dynamical guidance suggests that it could re-emerge around the end of next week. Although direct impacts are not expected, a substantial MJO event would enhance confidence in the forecast for the Northwest CONUS. A convectively coupled atmospheric Kelvin wave is traversing the Pacific ocean and the CFS forecasts Kelvin wave activity to continue over the next few weeks. Persistent wave activity can lead to enhanced moisture throughout the Southwest CONUS and below normal temperatures.
Forecast guidance this week is difficult to interpret over the Northwest. Most of our model guidance, including the CFS, JMA, and most of the SubX models indicate that the prominent ridging currently over the Northwest CONUS will continue through Weeks-3 and -4. This scenario would lead to anomalously warm temperatures underneath the ridge. However, the ECMWF model forecasts the ridge to weaken and retrograde west during Week-3, causing temperatures to be closer to their climatological average over the Northwest and above normal over Alaska. There have been a number of shortwaves moving through the ridge lately and more are forecast over the next couple of weeks. This lends confidence that the ridge will break down during Week-3, so we have sided with the ECMWF solution of equal chances of above and below normal temperatures for the Northwest and above average temperatures over Alaska for this forecast.
Models are in good agreement that above normal temperatures are expected in most of California and western Nevada, and east of the Rockies due to ridging that sets up over the eastern half of the CONUS. Tropical flows are expected in the Four Corners region and Southeast as tropical wave activity intensifies during the forecast period and precipitation in those areas is forecast to be above normal. Dynamical guidance throughout the week has consistently forecast slight ridging over Texas, which is likely to cause below normal precipitation during Weeks 3-4.
Dynamical models are forecasting a northern movement of the ITCZ during Weeks 3-4 over the Central Pacific. This is also supported by anomalously warm SSTs in the region. Therefore, our forecast is for anomalously wet and warm conditions over Hawaii during the forecast period.
Some Indices of Possible Interest:
Madden Julian Oscillation (MJO)
NCEP-NEFS | CFSv2 |
Analogs to the Outlook.
Now let us take a detailed look at the “Analogs”.
NOAA normally provides two sets of Analogs.
A. Analogs 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 the recent pattern is used to initialize the models to predict the 6 – 14 day Outlook.
B. There is a second set of analogs associated with the Outlook. It compares the forecast (rather than the prior period) to past weather patterns. I have not been regularly analyzing this second set of information. The first set applies to the 5 and 7 day observed pattern prior to today. The second set, relates to the correlation of the forecasted outlook 6 – 10 days out and 8 – 14 days out with similar patterns that have occurred in the past during a longer period that includes the dates covered by the 6 – 10 Day and 8 – 14 Day Outlook. The second set of analogs also has useful information as it indicates that the forecast is feasible in the sense that something like it has happened before. I am not very impressed with that approach. But in some ways both Approach A and B are somewhat similar. I conclude that if the Ocean Condition now are different then the analogs and if the state of ENSO now is different than the analogs that is a reason to have increased lack of confidence in the forecasts and vice versa.
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. But NOAA prefers the first set (A) as it helps them (or at least they think it does) assess the quality of the forecast.
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. It also helps the reader see the impact of the phases of the PDO and AMO which are shown. The first set (A) which is what I am using today applies to the 5 and 7 day observed pattern prior to today.
Centered Day | ENSO Phase | PDO | AMO | Other Comments |
Jun 26, 1951 | El Nino | – | + | Start of |
Jun 14, 1970 | La Nina | – | – | Start of powerful La Nina |
Jul 1, 1975 | La Nina | – | – | |
Jul 2, 1975 | La Nina | – | – | |
Jun 22, 1989 (2) | La Nina | + | – | Tail End |
Jun 28. 1995 (2) | Neutral | + | + | Just before a La Nina |
Jun 9, 2006 | Neutral | + | + | |
Jun 10, 2006 | Neutral | + | + |
(t) = a month where the Ocean Cycle Index has just changed from a consistent pattern or does change the following month to a consistent pattern.
The spread among the analogs from June 9 to July 2 is 23 days. 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, and fairly accurate if the dates are reasonably evenly distributed, is about June 20. These analogs are centered on 3 days and 4 days ago (June 14 or June 15). So the analogs could be considered to be out of sync with respect to weather that we would normally be getting right now but weather we might expect a week from now.
For more information on Analogs see discussion in the GEI Weather Page Glossary. For sure it is a rough measure as there are so many historical patterns but not enough to be a perfect match with current conditions. I use it mainly to see how our current conditions match against somewhat similar patterns and the ocean phases that prevailed during those prior patterns. If everything lines up I have my own measure of confidence in the NOAA forecast. Similar initial conditions should lead to similar weather. I am a mathematician so that is how I think about models.
Including duplicates, there are just like last week four Neutral Analog, five La Nina analogs and one El Nino Analog. The pre-forecast analogs this week do not strongly favor any particular McCabe Condition. That there is only one El Nino analog suggests that El Nino is not yet having a significant impact on the atmosphere where the analogs are measured.
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.
In color | Black and White same graphics |
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.
Historical Anomaly Analysis
When I see the same dates showing up often I find it interesting to consult this list.
A Useful Read
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.
Recent CONUS Weather
This is provided mainly to see the pattern in the weather that has occurred recently.
The U.S. Drought Monitor is a comprehensive way of understand the drought situation for the U.S. If is issued every Thursday and reflects the conditions as of the prior Tuesday. The drought monitor is not just based on precipitation but the condition of the land so it generally reflects more than a month’s precipitation and temperature and wind. The latest version of our report can be found here.
B. Beyond Alaska and CONUS Let’s Look at the World which of course also includes Alaska and CONUS
It is Useful to Understand the Semipermanent Pattern that Control our Weather and Consider how These Change from Winter to Summer. These two graphics (click on each one to enlarge) are from a much larger set available from the Weather Channel. They highlight the position of the Bermuda High which they are calling the Azores High in the January graphic and is often called NASH and it has a very big impact on CONUS Southeast weather and also the Southwest. You also see the north/south migration of the Pacific High which also has many names and which is extremely important for CONUS weather and it also shows the change of location of the ITCZ which I think is key to understanding the Indian Monsoon. A lot of things become much clearer when you understand these semi-permanent features some of which have cycles within the year, longer period cycles and may be impacted by Global Warming. We are now moving into late-June and should be returning to the set of positions shown below for July (and that appears to be happening at least in the Pacific).For CONUS, the seasonal repositioning of the Bermuda High and the Pacific High are very significant. Notice the Winter position of the Pacific High (Hawaiian High). It has been further south than usual for this time of the year. But it is forecast to retreat north to allow the Southwest Monsoon to happen.
Forecast for Today (you can click on the maps to enlarge them)
Temperature. | Precipitation. |
Not a lot of surprises here. But Equatorial Africa is again very warm. So is India | The pattern is changing. We no longer see the well defined dry belt. |
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 |
Please remember this graphic updates every six hours so the diurnal pattern can confuse the reader. | Other than the Equator, it looks quite dry. |
And now we have experimental forecasts from the U.S. NAEFS Model. They are difficult to read without first enlarging them.
Temperature | Precipitation |
You can really see that Northern Africa is quite warm. | You have click on this to read it. There are a lot of extremes dry and wet shown. |
Looking Out a Few Months
Here is the precipitation forecast from Queensland Australia:
It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. This graphic has been updated and now is in line with the actual SOI. Of interest is the wet China.
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
My focus here is sea surface temperature anomalies as they are one of the two largest factors determining weather around the World. If we want to have a good feel for future weather we need to look at the oceans as our weather mostly comes from oceans and we need to look at
- Surface temperature anomalies (weather develops from the ocean surface and
- The changes in the temperature anomalies since that may provide clues as to how the surface anomalies will change based on the current trend of changes. This is not that easy to do since the oceans are deep, there are many currents, winds have an impact etc. Two ways that are available to use are to look at the change in the situation today compared to the average over a period of time and NOAA also produces a graphic of monthly changes. I use both. The first set of graphics is simply looking at the average compared to today and that is below.
Three Month Average Anomaly | Current Anomaly |
La Nina starts to be displaced to the west. | We see a lot of white where we used to see blue. |
And when we look in more detail at the current Sea Surface anomalies below, we see a lot of them not just along the Equator related to ENSO. Currently this graphic is not updating so the discussion remains as per last week. If NOAA updates this graphic in the next day or so I might update the discussion.
Then we look at the change in the anomalies. The SST anomaly is sort of like the first derivative and the change in the anomaly is somewhat like a second derivative. It tells us if the anomaly is becoming more or less intense.
Here it gets a little tricky as for this graphic red does not mean a warm anomaly but a warming of the anomaly which could mean more warm or less cool and blue does not mean cool but more cool or less warm. | ||||
Mediterranean, Black Sea and Caspian Sea | Western North Pacific | West of North America | East of North America | North Atlantic |
Eastern Mediterranean and Black Sea warming, Caspian Sea cooling. Cooling off Somalia and Gulf of Aden, Arabian Sea, and south of India in general. | Warming off eastern Asia out to sea Cooling off Southeast Asia | Warming Bering Straits. Cooling west of Baja
. | Cooling off Nova Scotia and to the East. Cooling Eastern Hudson Bay Cooling western Caribbean | Warming British Isles. |
Equator | Eastern Pacific showing warming except to the extreme east near Ecuador. | |||
Africa | West of Australia | North, South and East of Australia | West of South America | East of South America |
Warming in Gulf of Guinea Warming off Namibia | Slightly warm | Cooling to the north. Slight warming to the Southeast Cooling around New Zealand. | Cooling off West Coast North of 50S Warming off 50S to 60S | Cooling from 30S to 40S Warming of 50S |
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. Notice the change in the PDO in July of 2017 and the stability of the AMO index.
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 | -0.67 | +0.39 | -0.3 | |
November | +0.84 | +0.40 | 0.0 | |
December | +0.56 | +0.34 | -0.1 | |
January | +0.12 | +0.23 | 0.0 | |
February | +0.05 | +0.23 | +0.2 | |
March | +0.14 | +0.17 | +0.0 | |
April | +0.53 | +0.29 | +0.2 | |
May | +0.29 | +0.32 | +0.2 | |
June | +0.21 | +0.31 | 0.0 | |
July | -0.50 | +0.31 | 0.0 | |
August | -0.62 | +0.31 | +0.4 | |
September | -0.25 | +0.35 | +0.2 | |
October | -0.61 | +0.44 | 0.0 | |
November | -0.46 | +0.35 | 0.0 | |
December 2017 | -0.13 | +0.36 | -0.4 | |
January 2018 | +0.29 | +0.17 | -0.1 | |
February | -0.18 | +0.06 | 0.0 | |
March | -0.58 | +0.13 | -0.1 | |
April | -0.76 | +0.06 | 0.0 | |
May | -0.1 |
Switching gears, below is an analysis of projected tropical hazards and benefits over an approximately two-week period.
* Moderate Confidence that the indicated anomaly will be in the upper or lower third of the historical range as indicated in the Legend. ** High Confidence that the indicated anomaly will be in the upper or lower third of the historical range as indicated in the Legend.
Tropical Activity Possibly Impacting CONUS.
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 (new) tropical events are expected to appear in this graphic during the next 48 hours. If that changes, we will provide an update.
Now let us look at the Western Pacific in Motion.
The above graphic which I believe covers the area from the Dateline west to 100E and from the Equator north to 45N normally shows the movement of tropical storms towards Asia in the lower latitudes (Trade Winds) and the return of storms towards CONUS in the mid-latitudes (Prevailing Westerlies). This is recent data not a forecast. But, it ties in with the Week 1 forecast in the graphic just above this graphic. Information on Western Pacific storms can be found by clicking here. This (click here to read) is an unofficial private source but one that is easy to read.
C. Progress of ENSO
A major driver of weather is Surface Ocean Temperatures. Evaporation only occurs from the Surface of Water. So we are very interested in the temperatures of water especially when these temperatures deviate from seasonal norms thus creating an anomaly. The geographical distribution of the anomalies is very important. To a substantial extent, the temperature anomalies along the Equator have disproportionate impact on weather so we study them intensely and that is what the ENSO (El Nino – Southern Oscillation) cycle is all about. Subsurface water can be thought of as the future surface temperatures. They may have only indirect impacts on current weather but they have major impacts on future weather by changing the temperature of the water surface. Winds and Convection (evaporation forming clouds) is weather and is a result of the Phases of ENSO and also a feedback loop that perpetuates the current Phase of ENSO or changes it. That is why we monitor winds and convection along or near the Equator especially the Equator in the Eastern Pacific.
Starting with Surface Conditions.
TAO/TRITON GRAPHIC (a good way of viewing data related to the part of the Equator and the waters close to the Equator in the Eastern Pacific where we monitor to determining the current phase of ENSO. It is probably not necessary in order 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.
Location Bar for Nino 3.4 Area Above and Below
———————————————— | A | B | C | D | E | —————– |
My Calculation of the Nino 3.4 Index
I calculate the current value of the Nino 3.4 Index each Monday 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 June 18, in the afternoon working from the June 17 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.
Calculation of Nino 3.4 from TAO/TRITON Graphic
Anomaly Segment | Estimated Anomaly | |
Last Week | This Week | |
A. 170W to 160W | +0.2 | +0.3 |
B. 160W to 150W | +0.2 | +0.2 |
C. 150W to 140W | +0.1 | +0.2 |
D. 140W to 130W | +0.2 | +0.3 |
E. 130W to 120W | +0.6 | +0.4 |
Total | +1.3 | +1.4 |
Total divided by five i.e. the Daily Nino 3.4 Index | (+1.3)/5 = +0.2 | (+1.4/5) = +0.3 |
My estimate of the daily Nino 3.4 SST anomaly tonight is again +0.3 which is clearly an ENSO Neutral value with an El Nino bias. NOAA has reported the weekly Nino 3.4 to be +0.2 which is clearly an ENSO Neutral value. Nino 4 is reported to be a bit warmer than last week +0.3. Nino 3 is reported to be the same as last week at +0.2. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported much cooler than last week at -1.0. It was up there close to -3.0 at one time so this index has been declining as an anomaly (rising) quite a bit and also fluctuating quite a bit which is not surprising as it is the area most impacted by the Upwelling off the coast. So it is an indication of the interaction between surface water and rising cool water. Thus it is subject to larger changes. I am only showing the currently issued version of the NINO SST Index Table as the prior values are shown in the small graphics on the right with this graphic. The same data in graphic form but going back a couple of more years can be found here. The full table of values can be found here.
This graphic brings the Nino 3.4 up to date and is easy to read. It may be more reliable than the NOAA readings. And Memorial Day is not a Holiday in Australia.
Here is another way of looking at the TAO/TRITON Graphic. It is a fast way to assess the strength of an ENSO Event and provides a way to track it.
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 by ENSO Phase | |
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) | NA | NA | 0 | 0 | 25 |
+0.5C to +1C (marginal) | 145W | 105W | 40 | 25 | |
These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator | |||||
0.5C or cooler Anomaly (warmish neutral) | 170E105W | 145WLAND | 45 | 25 | 25 |
0C or cooler Anomaly (coolish neutral) | LAND | LAND | 0 | 0 | |
These Rows Below Show the Extent of La Nina Impacts on the Equator. | |||||
-0.5C or cooler Anomaly | LAND | LAND | 0 | 0 | 0 |
-1.0C or cooler Anomaly | LAND | LAND | 0 | 0 | |
-1.5C or cooler Anomaly | LAND | LAND | 0 | 0 | |
-2.0C or cooler Anomaly | LAND | LAND | 0 | 0 | |
-2.5C or cooler Anomaly | LAND | LAND | 0 | 0 | |
This week there are zero degrees of longitude along the Equator in the Nino 3.4 Measurement Area which registers La Nina values. There are 25 degrees that register El Nino. The other 25 degrees register Neutral. That is not the case for the full +5N and +5S width of the Nino 3.4 Measurement Area but in this analysis we are just looking at the Equator. Roughly speaking, the ratio of the Neutral Value to 50 tells us if we are close to being in Neutral. |
The next graphic overlaps with the subsequent topic but I will show it here.
The discussion in this slide says it better than I could. One might compare the current reading to Oct/Nov 2017. The anomaly had returned to zero then reversed for a month and then returned to zero and now has gone positive. In retrospect it was the Kelvin Wave (#1) Activity the Upwelling Phase and the MJO which caused the brief reversal of the warming trend. We now have Kelvin Wave #2 and perhaps Kelvin Wave #3 so we should expect this warm anomaly to steadily increase for a while.
Side by side comparison can be useful
Comparison Week Probably Third Week of December 2017 | Current Week |
Sea Surface Temperature and Anomalies
It is the ocean surface that interacts with the atmosphere and causes convection and also the warming and cooling of the atmosphere. So we are interested in the actual ocean surface temperatures and the departure from seasonal normal temperatures which is called “departures” or “anomalies”. Since warm water facilitates evaporation which results in cloud convection, the pattern of SST anomalies suggests how the weather pattern east of the anomalies will be different than normal.
A major advantage of the Hovmoeller method of displaying information is that it shows the history so I do not need to show a sequence of snapshots of the conditions at different points in time. This Hovmoeller provides a good way to visually see the evolution of this ENSO event. I have decided to use the prettied-up version that comes out on Mondays rather that the version that auto-updates daily because the SST Departures on the Equator do not change rapidly and the prettied-up version is so much easier to read. The bottom of the Hovmoeller shows the current readings. Remember the +5, -5 degree strip around the Equator that is being reported in this graphic. So it is the surface but not just the Equator.
This next graphic is more focused on the Equator and looks down to 300 meters rather than just being the surface.
We wondered if there might be a third Kelvin Wave forming which would result in an El Nino rather than ENSO Neutral. We said: “It almost looks like we have another Down-welling Kelvin Wave without ever having the upwelling phase. That could be very important: It seems that NOAA agrees with our eyeballing of the graphic and last week drew in another down-welling Kelvin Wave. We do not want to go overboard on this but it is pretty significant. It is somewhat difficult to tell exactly how many separate Kelvin Waves they have been with the up-welling phase of Wave #2 non-existent or very faint. But NOAA has three down-welling dashed lines drawn in and I am working off that information.
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).
.
Anomalies are strange. You can not really tell for sure if the blue area is colder or warmer than the water above or below. All you know is that it is cooler than usual for this time of the year. A later graphic will provide more information. Aside from buoyancy the currents tend to bring water from that depth up to the surface mostly farther east. These currents are very complicated and made even more so by the uneven nature of the ocean floor. So the exact pattern of where this warm water will erupt is beyond my level of understanding. But it will erupt to the surface in multiple different places.
Now for a more detailed look. Below is the pair of graphics that I regularly provide. The date shown is the midpoint of a five-day period with that date as the center of the five-day period. The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters. At different times I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years except along the Equator where it is adjusted every five years) and how both measures are useful for other purposes.
We now have warm water with a maximum anomaly of +3C from 150W almost to LAND with additional warm water, but not quite as warm, extending west to Indonesia. |
The 28C Isotherm is now east of the Dateline at 170W, the 27C Isotherm is at 130W, the 25C Isotherm is now east of 100W. The 20C Isotherm is no longer close to reaching the surface near the coast due to reduced impact of the cool water being pushed to the surface by Kelvin Waves #2 and #3. |
Tracking the change.
And now let us look at the atmosphere.
And Now the Air Pressure to Confirm that the Atmosphere is Reacting to the Sea Surface Temperature Pattern. The most Common way to do that is to use 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.
Current SOI Readings
The 30 Day Average on June 18, 2018 was reported as -1.74 which is an ENSO Neutral value but now with an El Nino bias. The 90 Day Average was reported at 1.87 which is an ENSO Neutral value. Looking at both the 30 and 90 day averages is useful with the 90 day lagging the 30 day as one would expect. They are not in full agreement at this point in time which is typical of a transition from one ENSO Phase to another. . |
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
Here is the primary NOAA model for forecasting the ENSO Cycle. | The CDAS model is a legacy “frozen” NOAA system meaning the software is maintained but not updated. We find it convenient to obtain this graphic from Tropical Tidbits.com |
This model is forecasting El Nino. I am not longer showing the larger version of this graphic but if you click on it it will enlarge. Also, click here to see a month by month version of the same model but without some of the correction methodologies applied. It gives us a better picture of the further out months as we are looking at monthly estimates versus three-month averages. | Notice that since February, 2018 the Nino 3.4 Index has been rising. The CDAS data is not in conflict with the primary NOAA model but shows daily values rather then smoothing them out like the CFSv2 Model does. The CDAS data has now risen to neutral with an El Nino Bias. But it has recently returned to just plain neutral. |
The CFS.v2 is not the only forecast tool used by NOAA. The CPC/IRI Analysis which is produced out of The International Research Institute (IRI) for Climate and Society at Columbia University is also very important to NOAA.
Here is the most recent update.
Here is the discussion released on June 14, 2018
IRI ENSO Forecast CPC/IRI ENSO Update Published: June 14, 2018
El Niño/Southern Oscillation (ENSO) Diagnostic Discussion issued jointly by the Climate Prediction Center/NCEP/NWS and the International Research Institute for Climate and Society
ENSO Alert System Status: El Niño Watch
Synopsis: ENSO-neutral is favored through Northern Hemisphere summer 2018, with the chance for El Niño increasing to 50% during fall, and ~65% during winter 2018-19.
ENSO-neutral continued during May, as indicated by mostly average sea surface temperatures (SSTs) across the central and eastern equatorial Pacific. The latest weekly Niño indices were between +0.2°C and 0.0°C, except for the Niño-1+2 index, which remained negative (-0.5°C). Positive subsurface temperature anomalies (averaged across 180°-100°W) increased over the past month, as another downwelling equatorial oceanic Kelvin wave reinforced the already above-average subsurface temperatures. Convection remained suppressed near the Date Line and was slightly enhanced over Indonesia. Low-level and upper-level winds were near average across the equatorial Pacific Ocean. Overall, oceanic and atmospheric conditions reflected ENSO-neutral.
The majority of models in the IRI/CPC plume predict ENSO-neutral to continue through the Northern Hemisphere summer 2018, with El Niño most likely thereafter. The forecaster consensus favors the onset of El Niño during the Northern Hemisphere fall, which would then continue through winter.
These forecasts are supported by the ongoing build-up of heat within the tropical Pacific Ocean. In summary, ENSO-neutral is favored through Northern Hemisphere summer 2018, with the chance for El Niño increasing to 50% during fall, and ~65% during winter 2018-19 (see the 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 above is based on looking at a variety of models and other information but we should not forget that NOAA has their own model. Which was shown earlier and can be clicked on. So I do not plan to show the larger version as I have been doing in this part of the Report.
And here is what is called the plume of a variety of forecast models. We will have an update on this graphic soon.
Forecasts from Other Meteorological Agencies.
Here is the newly issued JAMSTEC Model Forecast
And the short recently issued discussion related to the May 1 ENSO forecast.
May 22, 2018 Prediction from 1st May, 2018
ENSO forecast:
The SINTEX-F predicts that a moderate-to-strong El Niño event may start in late summer this year and reach its peak in winter.
Indian Ocean forecast:
Occurrence of a positive Indian Ocean Dipole is clearly predicted by the SINTEX-F seasonal prediction system; the ensemble mean prediction suggests its evolution from early summer and its peak in fall. In accord to the positive IOD evolution, sea level anomalies are expected to be negative (positive) in the eastern (western) tropical Indian Ocean. We may observe co-occurrence of a positive Indian Ocean Dipole and an El Niño-like state in the latter half of 2018; this is just as we observed in 1997 and 2015.
Regional forecast:
On a seasonal scale, most part of the globe will experience a warmer-than-normal condition in summer, while some parts of northern central Russia, India, Southeast Asia, northern Australia, Mexico, and South American Continent will experience a cooler-than-normal condition. In fall, most part of the globe will be a warmer-than-normal condition, while some parts of northern Europe, U. K., East Africa, southern India, Indonesia, the Philippines, western US, eastern Canada, and northern Brazil will experience a relatively cold condition
As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for most parts of India, southern West Africa, western U.S. and northern parts of South American Continent, while Indonesia, eastern China, North/South Korea, some parts of Europe, central U.S., southern Mexico, and Australia will experience a drier-than-normal condition during boreal summer. In fall, we expect a drier-than-normal condition in Northern Europe, northern India, southern China, Indonesia, and Australia will be drier than normal partly due to the expected positive Indian Ocean Dipole.
Most part of Japan will experience warmer and relatively wetter-than-normal conditions in summer. Monthly prediction (not sown) suggests an active rainy season (Baiu) in June. In fall, most part of Japan will experience warmer and relatively drier-than-normal conditions.
Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)
And the ENSO Outlook Discussion Issued on June 19, 2018
El Niño WATCH; chance of El Niño in spring increases to 50%
The El Niño–Southern Oscillation (ENSO) remains neutral. However, latest model outlooks and recent warming in the tropical Pacific Ocean indicates that the chance of El Niño forming in spring has increased. As a result, the Bureau’s ENSO Outlook status has moved to El Niño WATCH. El Niño WATCH means that the likelihood of El Niño forming in 2018 is approximately 50%; double the normal chance.
Oceanic indicators are currently neutral—neither El Niño nor La Niña—but show some signs of potential El Niño development. Sea surface temperatures in the eastern Pacific Ocean, though currently neutral, have been slowly warming since April. Importantly, waters below the surface of the tropical Pacific are now warmer than average—a common precursor to El Niño.
The majority of international climate models surveyed by the Bureau forecast the tropical Pacific Ocean will continue to warm but stay in the neutral range during July and August. However, five of eight models indicate the ocean warmth is likely to reach El Niño thresholds in the southern hemisphere spring, while a sixth model falls just short.
During El Niño, rainfall in eastern Australian is typically below average during winter and spring. A neutral ENSO phase has little effect on Australian climate.
Indian Ocean IOD (It updates every two weeks)
Indian Ocean Dipole Outlook Discussion Issued June 19 2018
The Indian Ocean Dipole (IOD) remains neutral. The weekly index value to 17 June was −0.55 °C. Five of the six international climate models surveyed by the Bureau anticipate that the IOD will remain neutral until at least the southern hemisphere spring. However, one model indicates a positive IOD is likely to develop in the next month, with another approaching positive IOD thresholds during late winter and early spring, but remaining neutral.
It is useful to understand where and how the IOD is measured.
IOD Positive is the West Area being warmer than the East Area (with of course many adjustments/normalizations). IOD Negative is the East Area being warmer than the West Area. Notice that the Latitudinal extent of the western box is greater than that of the eastern box. This type of index is based on observing how these patterns impact weather and represent the best efforts of meteorological agencies to figure these things out. Global Warming may change the formulas probably slightly over time but it is costly and difficult to redo this sort of work because of long weather cycles.
D. Putting it all Together.
At this time La Nina Conditions along the Equator have come to an end and we are solidly into ENSO Neutral. The actual impacts on Worldwide weather lag the change in conditions along the Equator so we may have impacts from this transitioning La Nina for a short period of time but these impacts seem to be tailing off quite dramatically. In fact the Pacific Tropical activity which often precedes an El Nino is more of a factor right now.
Forecasting Beyond Five Years.
So in terms of long-term forecasting, none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast.
The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.
The odds of a climate shift for the Pacific taking place has significantly increased. It may be in progress. The AMO is pretty much neutral at this point so it may need to become a bit more negative for the “McCabe A” pattern to become established. That seems to be slow to happen so I am thinking we need at least a couple more years for that to happen. Our assessment is that the standard time for Climate Shifts in the Pacific are likely to prevail and it most likely will be a gradual process with a speed up in less than five years but more than two years. The next El Nino may be the trigger and it is probably three or more years out.
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 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.
The below diagram shows the usual location of the Indo-Pacific Warm Pool. When the warm water shifts to the east we have an El Nino; to the west a La Nina.
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 | |
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Eastern Pacific Easterlies |
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Western Pacific Westerlies |
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MJO Active Phase |
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MJO Inactive Phase |
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History of ENSO Events as measured by the ONI
The new SON reading of -0.4 is no longer La Nina Reading. Not all Meteorological Agencies Worldwide will necessarily accept this La Nina to be legitimately declared but most will. The full history of the ONI readings can be found here. The MEI index readings can be found here.
Four Quadrant Jet Streak Model Read more here This is very useful for guessing at weather as a trough passes through. It would apply to the states that are at the apex of the trough.
If the centripetal accelerations owing to flow curvature are small, then we can use the “straight” jet streak model. The schematic figure directly below shows a straight jet streak at the base of a trough in the height field. The core of maximum winds defining the jet streak is divided into four quadrants composed of the upstream (entrance) and downstream (exit) regions and the left and right quadrants, which are defined facing downwind.
Isotachs are shaded in blue for a westerly jet streak (single large arrow). Thick red lines denote geopotential height contours. Thick black vectors represent cross-stream (transverse) ageostrophic winds with magnitudes given by arrow length. Vertical cross sections transverse to the flow in the entrance and exit regions of the jet (J) are shown in the bottom panels along A-A’ and B-B’, respectively. Convergence and divergence at the jet level are denoted by “CON” and “DIV”. “COLD” and “WARM” refer to the air masses defined by the green isentropes.
[Editor’s Note: There are many undefined words in the above so here are some brief definitions. Isotachs are lines of equal wind speed. Convergence is when there is an inflow of air which tends to force the air higher with cooling and cloud formation. Divergence is when there is an outflow of air which tends to result in air sinking which causes drying and warming, Confluence is when two streams of air come together. Diffluence is when part of a stream of air splits off.]
Here is a time sequence animation. You may have to click on them to get the animation going.
When we discuss the jet stream and for other reasons, we often discuss different layers of the atmosphere. These are expressed in terms of the atmospheric pressure above that layer. It is kind of counter-intuitive to me. The below table may help the reader translate air pressure to the usual altitude and temperature one might expect at that level of air pressure. It is just an approximation but useful.
Re the above, H8 is a frequently used abbreviation for the height of the 850 millibar level (which is intended to represent the atmosphere above the Boundary Layer most impacted by surface conditions), H7 is the 700 mb level, H5 is the 500 mb level, H3 is the 300 mb level. So if you see those abbreviations in a weather forecast you will know what they are talking about.