May 29, 2017 Weather and Climate Report - West to East Divide for CONUS

Written by Sig Silber

Last week we observed a decline in Ocean surface temperature anomalies which continues. That should ratchet down weather in most parts of the World. For CONUS we expect a warm West and a cool East. The Northwest will be dry soon and the East Coast wet to some degree with the Southern Plains States joining in early before the pattern progresses to the east over time. The Southeast may have some severe weather. The chances of an El Nino continue to decline, in our opinion.

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First some housekeeping information. For those who want the forecasts beyond three months, we recently reported on the recent NOAA and JAMSTEC Seasonal Forecasts and compared them in a Special Update that you can get to by clicking here. More recently we provided an Update on the possible El Nino this Winter that many meteorological models until recently have been forecasting. We think it is implausible and our report can be accessed by clicking here. It seem that NOAA and BOM (Australia) are coming around to our way of thinking on this but JAMSTEC (Japan) is still bullish on an El Nino this winter. Remember if you leave this page to visit links provided in this article, you can return by hitting your “Back Arrow”, usually top left corner of your screen just to the left of the URL box.

A. Focus on Alaska and CONUS (all U.S.. except Hawaii)

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. In this graphic you can see some Pacific moisture entering the picture contributing to the moisture entering from the Gulf of Mexico.

Tonight, Monday evening May 29, 2017, as I am looking at the above graphic, we see mostly thunderstorm activity in the Southeast.

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.

One sees the current jet stream above. It seems to be up and over a ridge and showing up more in the Eastern Part of the U.S.

This graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.

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.

This evening we see the southeast activity and moisture swirling around a Low Pressure Area over the Great Lakes.

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.

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

But let’s not forget the upcoming Hurricane Season. It may be getting off to an early start. So we need to start watching this graphic again.

When there is activity and I have not provided the specific links to the storm of interest, one can obtain that information at this link.

U.S. 3 Day to 7 Day Forecasts

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 3. The Day 6 forecast can be found here.

When I look at this Day 3 forecast, the Low of most interest probably is the one in the Gulf of Alaska which has a surface central air pressure of 1000 hPa. The Aleutian Low has turned from a semi-permanent feature into a train of Lows which one expects this time of the year. Remember, this is a forecast for Day 3 not the current situation.

The High Pressure off of the West Coast, the familiar RRR or more properly called the Eastern Pacific Semi-tropical High or the Hawaiian High is weak and far south. It has a surface central air pressure of 1020 hPa which is quite low. There is thus now for Day 3 no block on Pacific Storms entering CONUS. Of interest perhaps is the Low over Hudson Bay that reaches down to the Great Lakes.

I provided this K – 12 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 3. It is not the current situation but Day 3 is not very far out.

But now let us look at Day 6

The forecast situation has changed. The High has moved to the north and thus the precipitation stream is also shifted north into Canada. That explains the 6 – 10 Day Forecast which calls for a dry Northwest.

Now looking at the 5 Day Jet Stream Forecast

This is a Day 5 forecast by one model. The activity is north of CONUS for the most part until it reaches the Great Lakes. Remember this is a H3 view meaning a view at 30,000 feet which is about six miles high.

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.

Re the above, H8 is a frequently used abbreviation for the height of the 850 millibar level, 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.

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.

We see again the pattern of a wet Southeast fed mostly by moisture from the Gulf of Mexico.

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.

Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.

What we see for Day 7 is a West Coast/Rocky Mountains Trough, a Central Ridge and a Great Lakes Trough/Low. We might even see the Monsoonal Ridge building over Mexico.

Remember this is a forecast for Day 7. Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. Thickness lines near or over 600 tend to suggest very warm temperatures. So that is what we will be focusing on now re the need for heat warnings.

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 provide the June and three-month JJA maps which are issued and updated less frequently than the first three maps shown.

mall Images of Temperature Maps
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.

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 May 29, 2017 was 3 out of 5)

8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on May 29, 2017 was 2 out of 5)

Looking further out.

Consolidation of 6 – 10, 8 – 14 and Experimental Week 3-4 Temperature Forecasts
Interpreted on May 29, 2017
June 4 to June 12	June 10 to June 23
Days 6 – 10: CONUS is warm in the West and cool in the East but warm in Florida. Alaska is warm in the north and cool in the south and the Panhandle.	The Northwest is warm anomaly is reduced to just the Primary Northwest. From Mid-New Mexico to Maine the edge of CONUS is warm. There is a cool anomaly mid-Rocky Mountains. Alaska is warm in the North and the Panhandle. The transition to the pattern shown in the Week 3 – 4 Forecast from the pattern shown in the 8-14 Day forecast seems to be unlikely.
Week 2: As the period evolves, the CONUS pattern does not change very much but the anomalies moderate..
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.

Here 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 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.

The theory behind using dynamical models for short-term forecasts (6 10 Days, 8 – 14 Days, and recently Weeks 3-4) and statistical models (Monthly and Three-Months) for longer-term forecasts makes perfect sense but sometimes we see that the short term forecasts and then the actuals do not match the statistical forecasts very well. This tells us that either the statistical forecasts were based on incorrect assumptions or that the actual weather patterns are different from what we might have expected.

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 that has the three small images, you can find the larger maps and a discussion that ties the three maps together. For reference purposes, I then provide the June and three month JJA maps which are issued and updated less frequently than the first three maps shown.

Small Images of Precipitation Maps
6 to 10 Day	8 to 14 Day	Weeks 3 and 4

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 May 29, 2017 was 3 out of 5)

8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on May 29, 2017 was 2 out of 5)

Looking further out.

Consolidation of 6 – 10, 8 – 14, and Week 3-4 Precipitation Forecasts
Interpreted on May 29, 2017
June 4 to June 12	June 10 to June 23, 2017
Days 6 -10: The Northwest of CONUS is dry as is the Great Lakes Region. Much of the rest of CONUS especially to the south and east is wet. Alaska is wet.	For CONUS, Oregon and Washington are dry. The Eastern half of CONUS is wet. Southern 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 seems to be feasible early in the period but not necessarily for the full two weeks.
Week 2: There is not much change except the Great Lakes Region is engulfed by the wet anomaly which has generally moved to the east. .
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.

Her 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.

The theory behind using dynamical models for short-term forecasts (6 – 10 Days, 8 – 14 Days and recently Weeks 3-4) and statistical models for longer-term forecasts (Month and three months) makes perfect sense but sometimes we see that the short-term forecasts and then the actuals do not match the statistical forecasts very well. This tells us that either the statistical forecasts were based on incorrect assumptions or that the actual weather patterns are different from what we might have expected.

Here is the NOAA discussion released today May 29, 2017.

6-10 DAY OUTLOOK FOR JUN 04 – 08 2017
TODAY’S DYNAMICAL MODEL SOLUTIONS FOR THE 6-10 DAY PERIOD ARE IN GOOD AGREEMENT ON THE 500-HPA CIRCULATION PATTERN PREDICTED OVER NORTH AMERICA. TROUGHS ARE ANTICIPATED OVER THE EASTERN CONUS, THE WEST COAST, AND NEAR THE ALASKA PENINSULA, WHILE A RIDGE IS EXPECTED OVER THE NORTHERN HIGH PLAINS EXTENDING NORTHWARD OVER WEST-CENTRAL CANADA AND ALASKA. TODAY’S 500-HPA BLEND CHART DEPICTS NEAR TO BELOW NORMAL HEIGHTS OVER MOST OF THE EASTERN CONUS, AND SOUTHWESTERN ALASKA, WHILE NEAR TO ABOVE NORMAL HEIGHTS ARE ANTICIPATED OVER WESTERN CONUS AND OVER THE REMAINDER OF ALASKA. THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE MODERATE TO LARGE SPREAD ACROSS THE MAJORITY OF THE FORECAST DOMAIN. THE GREATEST WEIGHT FOR THE BLENDED HEIGHT FORECAST WAS GIVEN TO THE ECMWF ENSEMBLE MEAN BASED ON CONSIDERATIONS OF RECENT SKILL AND ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.
ABOVE NORMAL HEIGHTS ENHANCE PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WESTERN CONUS. TROUGHING AND ASSOCIATED NEAR TO BELOW NORMAL HEIGHTS TILT THE ODDS TO NEAR TO BELOW NORMAL TEMPERATURES FOR MUCH OF THE CENTRAL AND EASTERN CONUS. THE EXCEPTION IS OVER THE FLORIDA PENINSULA WHERE ABOVE NORMAL SSTS FAVOR ABOVE NORMAL TEMPERATURES. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR NORTHWESTERN ALASKA AND BELOW NORMAL TEMPERATURES ARE FORECAST FOR SOUTHEASTERN ALASKA CONSISTENT WITH CALIBRATED TEMPERATURES FROM THE GFS ENSEMBLE MEMBERS.
A TROUGH OVER THE EASTERN CONUS ENHANCES PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE EASTERN CONUS, WHILE RIDGING OVER THE NORTHERN HIGH PLAINS AND ANOMALOUS NORTHERLY FLOW FAVOR BELOW MEDIAN PRECIPITATION FOR MUCH OF THE NORTHERN TIER OF THE CONUS WEST OF THE GREAT LAKES. BELOW MEDIAN PRECIPITATION IS ALSO FAVORED FOR THE NORTHWESTERN CONUS UNDERNEATH ABOVE NORMAL HEIGHTS. ABOVE MEDIAN PRECIPITATION IS FORECAST FOR PARTS OF THE GREAT PLAINS, WHICH IS CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS. THE TROUGH NEAR THE ALASKA PENINSULA TILTS THE ODDS TO ABOVE MEDIAN PRECIPITATION FOR MUCH OF ALASKA.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD AGREEMENT AMONG THE MODEL SOLUTIONS OFFSET BY SOME DISAGREEMENTS AMONG THE FORECAST TOOLS.
8-14 DAY OUTLOOK FOR JUN 06 – 12 2017
DURING THE WEEK-2 PERIOD, A LOW AMPLITUDE PATTERN IS PREDICTED OVER MUCH OF THE FORECAST DOMAIN DUE, IN PART, TO DISAGREEMENTS AMONG THE ENSEMBLE MEMBERS. WEAK TROUGHS ARE FORECAST OVER THE EASTERN CONUS, THE INTERIOR NORTHWEST, AND OVER THE BERING SEA/ALEUTIANS/ALASKA PENINSULA, WHILE WEAK RIDGING IS INDICATED OVER PARTS OF MAINLAND ALASKA. TODAY’S 500-HPA BLEND CHART DEPICTS NEAR TO BELOW NORMAL HEIGHTS OVER THE EASTERN CONUS, WHILE NEAR TO ABOVE NORMAL HEIGHTS ARE ANTICIPATED OVER THE WESTERN CONUS. THE GREATEST WEIGHT WAS GIVEN TO THE ECMWF ENSEMBLE MEAN BASED ON CONSIDERATIONS OF RECENT SKILL AND ANALOG CORRELATIONS.
THE RESULTING TEMPERATURE OUTLOOK IS VERY SIMILAR TO THAT FOR THE 6-10 DAY PERIOD. ABOVE NORMAL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WESTERN CONUS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE CENTRAL AND EASTERN CONUS IN ASSOCIATION WITH THE TROUGH OVER THE EASTERN CONUS EXCEPT FOR THE FLORIDA PENINSULA WHERE ABOVE NORMAL SSTS AND AIR TEMPERATURES ARE INDICATED. ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES ARE ALSO INDICATED FOR PARTS OF SOUTHEASTERN MAINLAND ALASKA CONSISTENT WITH GEFS REFORECAST GUIDANCE.
PREDICTED CYCLONIC FLOW LEADS TO ENHANCED PROBABILITIES FOR NEAR TO ABOVE MEDIAN PRECIPITATION FOR THE EASTERN CONUS. ENHANCED PROBABILITIES FOR BELOW-MEDIAN PRECIPITATION ARE INDICATED FOR THE NORTHWESTERN CONUS EXTENDING TO PARTS OF THE NORTHERN PLAINS UNDERNEATH ABOVE NORMAL HEIGHTS. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF ALASKA AHEAD OF THE TROUGH OVER THE BERING SEA.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO FAIR AGREEMENT AMONG THE MODEL SOLUTIONS AND POOR AGREEMENT AMONG THE FORECAST TOOLS.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON JUNE 15

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
May 16, 1952	Neutral	–	+
May 16, 1958	El Nino	+	+
May 17, 1958	El Nino	+	+
Jun 11, 1982	El Nino	– (t)	–	Powerful El Nino
May 27, 1983	El Nino	+	–	Tail end of above El Nino
May 15, 1985	La Nina	+	–
May 16, 1985	La Nina	+	–

(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 May 15 to June 11 which is 27 days which is a reasonable spread. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, is about May 28. These analogs are centered on 3 days and 4 days ago (May 25 or May 26). So the analogs could be considered to be just a bit out of in sync with the calendar meaning that we will be getting weather that we would normally have two or three days later in the year. The question is what if anything does this mean. For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are five El Nino Analogs, two La Nina analogs and one ENSO Neutral Analog. When you group them by event you end up with two El Ninos, one La Nina and one Neutral situation. The phases of the ocean cycles of the analogs are consistent with McCabe Conditions A and C which are opposite variants of PDO+ conditions. So it is not a surprise that NOAA’s models are not able to see out to Days 8 – 14 with much confidence. I think this is seaonal transition at work with a lot of movement of the Eastern Subtropical High that gets switching from its winter position to its summer position and back again.

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.

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 May 20, 2017

California is no longer wet. The West now shows a generally cool anomaly pattern. Remember this is a 30 day average with seven more recent days added and seven more distant days removed.

And the 30 Days ending May 27, 2017

Not a lot of change in the precipitation pattern. The temperature warm anomaly on the East Coast continues to moderate. Remember this is a 30 day average and seven days recent days are added and seven distant days are removed.

B. Beyond Alaska and CONUS Let’s Look at the World which of Course also includes Alaska and CONUS

I will be including the above two graphics regularly as they really help with understanding why things are happening the way they are. I think the (at least intermediate Source is The Weather Channel and I was able to download the full presentation with difficulty and you can attempt the same thing by clicking here.

I think these two slides are from a much larger set but these two really highlight the position of the Bermuda High which they are calling the Azores High in the January slide 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 what 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 at the end of May right now so we are 5/6ths between the two sets of positions shown above for January and July. For CONUS the repositioning of the Bermuda High and the Pacific High are very significant.

Todays Forecast

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. Antarctica is quite warm. There are there Northern Hemisphere cool anomalies shown.

This graphic is actuals not anomalies. We again see the wet area pretty much just south of the Equator. There is a lot of dry area including from Northern Africa to India and even into China which impacts a large number of people. There is not much that is wet in the Northern Hemisphere. Southern Africa, South America and Australia are dry. Southeast Asia and the Maritime Climate are wet.

Additional Maps showing different weather variables can be found here.

Near Term Forecast (Currently Set for Day 3 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 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.

Although I can not display the interactive control panel in my article, I can display any of the graphics it provides so below are the current worldwide precipitation and temperature forecasts for three days out. They will auto-update and be current for Day 3 whenever you view them. If you want the forecast for a different day Click Here

Precipitation

Notice that Northern South American remains wet but further north than usual. That seems to be a fairly semi-permanent feature right now. There is a big storm off of Europe.

Temperature

The pattern of warmth from North Africa to India Continues. The situation off the west coast of South America is interesting. Looks like the Humbolt Current has reappeared.

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. Notice the change from the forecast last month due to the rising SOI. It is a big change. But it is strange that the precipitation pattern for CONUS is across the Northern Tier.

JAMSTEC Forecasts

This month, JAMSTEC issued their ENSO forecasts and climate maps in early May. We issued a Special Update on May 20 that you can get to by clicking 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. 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. We will be publishing a new Update on June 17 of the new JAMSTEC and NOAA seasonal outlooks.

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. At the beginning of this report I showed a monthly average of these 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 Caspian Sea is slightly warm. The Mediterranean is warm.	Mostly warm but an intense cool area straddling the Dateline but now mostly east of the Dateline.	Slightly warm in Bering Straights. Cool off Baja.	Warm but again less so than usual. Cool off Newfoundland.	Neutral
The Tropical Pacific	Neutral with warm bias
Africa	West of Australia	North, South and East of Australia	West of South America	East of South America
Warm off Northwest Africa and Bay of Guinea. Warm Northeast of Madagascar.	Cool off Southwest Coast.	Warm off the Southeast Coast. Warm to the North.	Cool off of Peru*..Neutral elsewhere	Cool off of 20S. Warm south of 30S.

What you see in the below graphic is the change in the anomaly over the last four weeks [*very important re Peru which is showing cool today (actually yesterday) but has been warming which shows that one day does not make a trend] . So you have to refer to the graphic above this one to really interpret the below graphic as what we are seeing here is the change in the anomalies. So blue means a trend that is either cooler or less warm than four weeks ago. Red means a trend that is warmer or less cool than four weeks ago. So this graphic is a way of understanding how the anomalies shown in the above graphic have changed over the past four weeks.

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
Slight warming in the Black and Caspian Seas	Warming around Japan. Warming west and east of India.	Warming in Bering Straits. Cooling from California to the Equator.	Cooling but not as intense as off West Coast.	Stable
The Tropical Pacific	Cooling east mostly stable.
Africa	West of Australia	South and East of Australia	West of South America	East of South America
Ever so slight warming	Stable	Stable out to New Zealand where there is generalized cooling.	Extensive cooling	Cooling between 20S and 30S. Warming out to sea mostly south of 40S

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	+0.12	+0.23	0.0
February	+0.04	+0.23	+0.2
March	+0.08	+0.17	+0.0
April	+0.52	+0.29	+0.2

Switching gears, below is an analysis of projected tropical hazards and benefits over an approximately two-week period.

This graphic updates on Tuesdays and I post on Monday which is almost a week later than when this graphic was last updated. So Week Two applies at the time I write this article on Monday but by the time you read it on Tuesday the Week Two that I am looking at is updated and becomes Week One. Mostly I see as I look at this on May 29 for what is shown as Week Two, the period May 31, 2017 to June 6, 2017, we see dry conditions* west of the Isthmus of Panama, wet conditions* for the U.S. Gulf States, part of the Maritime Continent, and just north of the Equator in Africa. We also see the potential for tropical cyclone development* west of Indochina.

* 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.

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.Also you can see the break in the action of Pacific Storms headed east. 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 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.

Notice in the bottom graphic the big difference between temperature anomalies south of the Equator and north of the Equator. This creates a dynamic situation. The winds seem to be moving the warm water further south which reduces the level of recorded NINO indices.

*Location Bar for Nino 3.4 Area Above and Below*
————————————————	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
Subareas of the Anomaly	Westward Extension	Eastward Extension	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)	WARM POOL	WARM POOL	0	0
+0.5C to +1C (marginal)	WARM POOL	160E	0	0
These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly (warmish neutral)*	160E	LAND	105	50
0C or cooler Anomaly (coolish neutral)	LAND	LAND	0	0

* A warm anomaly exceeding +0.5C is showing South of the Equator in today’s TAO/TRITON Five-Day Mean Graphic. This week it has intruded north of the Equator as is shown in the Tao Triton graphic. I have not recorded it that way in the above table but will do so next week if that warmer Southern Hemisphere water continues to show up North of the Equator.

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 May 29, in the afternoon working from the May 28 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 ONI from TAO/TRITON Graphic*
Anomaly Segment	Estimated Anomaly
	Last Week	This Week
A. 170W to 160W	+0.7	+0.6
B. 160W to 150W	+0.9	+0.6
C. 150W to 140W	+0.6	+0.6
D. 140W to 130W	+0.7	+0.7
E. 130W to 120W	+0.6	+0.7
Total	+3.5	+3.2
Total divided by five i.e. the Daily Nino 3.4 Index	(+3.5)/5 = +0.7	(+3.2)/5 = +0.6

My estimate of the daily Nino 3.4 SST anomaly tonight is +0.6 which is an El Nino Value. NOAA has also reported the weekly Nino 3.4 to be +0.6 which is an El Nino Value.

Nino 4.0 is reported the same at +0.3. Nino 3 is a bit higher at +0.6. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported much lower at +0.4. I believe it was up there close to 3 at one time so this index has been fluctuation quite a bit and is what I think has fooled the models and the meteorologists earlier this year and continues to create confusion.

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 table form but going back a couple of more years can be found here.

This is probably the best place to express the thought that this way of measuring an ENSO event leaves a lot to be desired. Only the surface interacts with the atmosphere and is able to influence weather. The subsurface tells us how long the surface will remain cool (or warm). Anomalies are deviations from “Normal”. NOAA calculates and determines what is “Normal” which changes due to long ocean cycles and Global Warming. So to some extent, the system is “rigged”. Hopefully it is rigged to assist in providing improved weather forecasts. But to assume that any numbers reported can be assumed to be accurate to a high level of precision is foolhardy. It is strange to me that the Asian forecasting services generally conclude that that this cool ENSO Phase is not a La Nina but a near La Nina and NOAA concludes it is a La Nina. It is the same ocean. The reported readings are very close but the Asian readings are generally slightly higher (less La Nina-ish) than the NOAA reading and their cut-off points for declaring a La Nina are a bit different and the parts of the Equator they look at are a bit different. It might be explained by what part of the ENSO pattern impacts their area of geography but it just seems to me that NOAA has been a bit over eager. And I wonder why.

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 which are the current readings are now light yellow which is not El Nino warm but clearly on the warm side of Neutral. 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. Week to week there have been no substantial changes. It is ENSO Neutral with a warm bias.

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.

The bottom of the Hovmoeller shows the current situation. The Cool Event is long gone. But what might be successive Kevin waves initiating an El Nino are still not very impressive. If you look from the bottom of the graphic up you can see that any La Nina conditions ended in December. There is not much change from the prior week but a cooler area is no longer in the picture. But what I am really looking for is the left portion of the graphic the Pacific Warm Pool and I don’t see much change. Reds are what is needed for an El Nino. There could be another weak Kelvin Wave getting started but we will need a couple of weeks to see if that is the case. So far there is no indication of this but not shown in this report the overall pattern of Easterlies has declined a bit so there is a bit more opportunity for a Kelvin Wave to get started. So far the change has been small. Mid-May is the time when the next Rossby Wave moves through and that will be the best opportunity to have a boost to this flagging incipient El Nino.

NOAA did draw in an Upwelling Wave in the graphic three weeks ago presumably to be ready to draw in a Downwelling wave soon. And here it is. It has moved east to 130W. It generally is a pretty shallow layer. Two years there were five or six Kelvin waves the first ones quite strong.This is showing at 0.5C to 1.0C (orange color). No red and it covers a small area. Last week we said: “it almost looks like to the west you can see the passing of the wave i.e. it appears to have been not very wide more or less like the one in February”. Today we have confirmation of that.

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).

The pattern has changed a bit since last week. You can track the history of this graphic on the right. I think it shows the prior week and then every other week before then. There has not been a lot of change. There is no indication of an El Nino of any significance forming. There is no real warm water flow from the Indo-Pacific Warm Pool to the Eastern Pacific [just what you see and it is not enough to bake an El Nino]. There is a decent warm anomaly between 170E and 160W but no reinforcements behind it i.e.to the west. Further east the warm anomaly at depth has expanded a bit. The cool anomaly is still shown. Nothing very remarkable here. There is no red showing.

Now for a more detailed look. Notice by the date of the graphic (dated May 23, 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 but for different purposes.

Re the top graphic, let us first look at surface temperature anomalies. Warm water continues to extend from the Coast of Ecuador to 105W and slightly warm water all the way to 150W. Subsurface Temperature Anomalies: The cool water is almost gone. It may be totally gone by the next issue of this graphic. Notice the warm water at depth but there is a big gap east of 160W. There has been only modest change recently from report to report which are each approximately five days apart. These is some change from last week. But the overall pattern still seems to be ENSO Neutral to borderline El Nino. There is one very warm pocket of water now centered on the Dateline at 125 meters and slowly moving to the East and rising. The 0.5C anomaly covers 40 degrees of longitude. The 1.0C anomaly covers 30 degrees. At some point it is likely to rise in the Nino 3.4 Measurement Area and can create El Nino Conditions for a few months. But that most likely will not be sufficient to conclude that we had an El Nino. The trajectory seems to be such that it will appear to be a Modoki i.e. focused on the western part of the Nino 3.4 Measurement Area.

The bottom half of the graphic (Absolute Values which highlights the Thermocline) is now more useful as we track the transition from last winter’s ENSO Cool Event to ENSO Neutral to ENSO Neutral with a warm bias which may possibly become an El Nino.

It shows the thermocline between warm and cool water. The 28C Isotherm is again located at the 165W. This graphic does not show a 27.5C anomaly which might more precisely indicate where convection is likely to occur. The 27C isotherm is at 130W which is a lot further east than the 28C isotherm but no change from the last report. We do not yet have ideal (El Nino) conditions for significant convection along the Equator east of the Dateline. What we have is increasingly looking like ENSO Neutral. The 25C isotherm no longer extends all to the way to Ecuador which is less El Nino-ish. The 20C Isotherm is depressed by warmer water all the way to Ecuador.

The flattening of the Isotherm Pattern is an indication of ENSO Neutral just as the steepening of the pattern indicates La Nina or El Nino depending on where the slope shows the warm or cool pool to be. That flattening has occurred. At this point, we have gone to ENSO Neutral but not El Nino.

It does not appear likely that the conditions exist to create an El Nino. If you look at the top graphic and the warm anomaly centered on the Dateline, that is all there is for a potential El Nino to work with. That little +2C portion most likely if it moved to the surface would be neutral or just slightly warmer than neutral. You can tell that from the bottom graphic. It may be a +2C anomaly but it is probably +27C water which if it surfaced in the Nino 3.4 Measurement Area would not be much of a warm anomaly but close to neutral which you can tell by looking at the +27C isotherm at the Dateline in the bottom graphic. You can see the rise in the +27C Isotherm at that point. But +27C water if it rises to the surface would be essentially a Neutral ENSO value. Why the models have been fooled is a mystery to me.

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.

We now see easterly anomalies west of the Dateline which are not at all consistent with the formation of an El Nino.

And now the Outgoing Long wave Radiation (OLR) Anomalies which tells us where convection has been taking place.

The pattern has changed. We no longer see suppressed Outgoing Long Wave Radiation (OLR) at the Dateline (no longer dry) nor do we see enhanced OLR at 120E (no longer wet)

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.

**Current SOI Readings**
The 30 Day Average on May 29 was reported as -1.67 which is an ENSO Neutral value. The 90 Day Average was reported at -0,96 which is also ENSO Neutral. Looking at both the 30 and 90 day averages is useful and both are in agreement that we are in ENSO Neutral.

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 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

We now have both the early May (May 11) and Mid-May (May 18) reports from CPC/IRI I am showing both as it is a way of seeing the trend in forecasts even though the methodology of the two forecasts are not identical.

First we look at graphic on the left which is the IRI/CPC Survey-Based Report issued on May 11, 2017. Then we look on the right at the most recent (May 18) fully model based report. Notice the new report has much higher probabilities for El Nino than the prior report. The full discussion can be found is provided below.

IRI Technical ENSO Update
Published: May 18, 2017
Note: The SST anomalies cited below refer to the OISSTv2 SST data set, and not ERSSTv4. OISSTv2 is often used for real-time analysis and model initialization, while ERSSTv4 is used for retrospective official ENSO diagnosis because it is more homogeneous over time, allowing for more accurate comparisons among ENSO events that are years apart. During ENSO events, OISSTv2 often shows stronger anomalies than ERSSTv4, and during very strong events the two datasets may differ by as much as 0.5 C. Additionally, the ERSSTv4 may tend to be cooler than OISSTv2, because ERSSTv4 is expressed relative to a base period that is updated every 5 years, while the base period of OISSTv2 is updated every 10 years and so, half of the time, is based on a slightly older period and does not account as much for the slow warming trend in the tropical Pacific SST.
Recent and Current Conditions
In mid-May 2017, the NINO3.4 SST anomaly hovered near the borderline of a weak El Niño level. For April the SST anomaly was 0.32 C, and for Feb-Apr it was 0.20 C, both in the ENSO-neutral range. The IRI’s definition of El Niño, like NOAA/Climate Prediction Center’s, requires that the SST anomaly in the Nino3.4 region (5S-5N; 170W-120W) exceed 0.5 C. Similarly, for La Niña, the anomaly must be -0.5 C or less. The climatological probabilities for La Niña, neutral, and El Niño conditions vary seasonally, and are shown in a table at the bottom of this page for each 3-month season. The most recent weekly anomaly in the Nino3.4 region was 0.5, around the borderline of weak El Niño. The SST farther east has been at above-average levels for several months, and far above average during February and March making for a coastal warming event during the rainy season in coastal southern Ecuador and northern Peru. Most of the pertinent atmospheric variables, including the upper and lower level zonal wind anomalies, have been showing mainly neutral patterns. However, the Southern Oscillation Index (SOI) has recently been somewhat below average, indicating an El Niño tendency. Subsurface temperature anomalies across the eastern equatorial Pacific have become just slightly above average. Overall, given the SST and the atmospheric conditions, an ENSO-neutral diagnosis remains appropriate, with a tilt toward warm conditions.
Expected Conditions
What is the outlook for the ENSO status going forward? The most recent official diagnosis and outlook was issued one week ago in the NOAA/Climate Prediction Center ENSO Diagnostic Discussion, produced jointly by CPC and IRI; it stated that ENSO-neutral and El Niño have approximately equal chances during northern summer and fall, with just slightly higher chances for ENSO-neutral. The latest set of model ENSO predictions, from mid-May, now available in the IRI/CPC ENSO prediction plume, is discussed below. Those predictions suggest that the SST has equal chances of being in the ENSO-neutral or the weak El Niño range for May-Jul but show a slightly increased likelihood for El Niño development from summer onward.
As of mid-April, 32% of the dynamical or statistical models predicts neutral ENSO conditions for the initial May-Jul 2017 season, while 68% predicts El Niño conditions and 0% predicts La Niña conditions. At lead times of 3 or more months into the future, statistical and dynamical models that incorporate information about the ocean’s observed subsurface thermal structure generally exhibit higher predictive skill than those that do not. For the Aug-Oct 2017 season, among models that do use subsurface temperature information, no model predicts La Niña conditions, 67% predicts El Niño conditions, while 33% predicts neutral ENSO. For all model types, the probabilities for La Niña are 6% or lower for for all predicted seasons from May-Jul 2017 through Jan-Mar 2018. The probability for El Niño conditions is at least 60% throughout the series of forecast periods ending Jan-Mar 2008. The chances for El Niño rise to about 70% from Jul-Sep to Sep-Nov, and then hover between about 60% and 70% through Jan-Mar 2018. Chances for neutral ENSO conditions hover between about 30% to 40% throughout all the forecast seasons through Jan-Mar 2018.
Note – Only models that produce a new ENSO prediction every month are included in the above statement.
Caution is advised in interpreting the distribution of model predictions as the actual probabilities. At longer leads, the skill of the models degrades, and skill uncertainty must be convolved with the uncertainties from initial conditions and differing model physics, leading to more climatological probabilities in the long-lead ENSO Outlook than might be suggested by the suite of models. Furthermore, the expected skill of one model versus another has not been established using uniform validation procedures, which may cause a difference in the true probability distribution from that taken verbatim from the raw model predictions.
An alternative way to assess the probabilities of the three possible ENSO conditions is more quantitatively precise and less vulnerable to sampling errors than the categorical tallying method used above. This alternative method uses the mean of the predictions of all models on the plume, equally weighted, and constructs a standard error function centered on that mean. The standard error is Gaussian in shape, and has its width determined by an estimate of overall expected model skill for the season of the year and the lead time. Higher skill results in a relatively narrower error distribution, while low skill results in an error distribution with width approaching that of the historical observed distribution. This method shows probabilities for La Niña at 10% or less from May-Jul 2017 through the final season of Jan-Mar 2018. Probabilities for ENSO-neutral are 50% for May-Jul, falling to 42% by Jun-Aug, and remaining in the 30-40% range from Jul-Sep through Jan-Mar 2018. Probabilities for El Niño are 50% for May-Jul, peak at 60% for Aug-Oct and Sep-Nov, and hover in the 55-60% range from Oct-Dec through Jan-Mar 2018. A plot of the probabilities generated from this most recent IRI/CPC ENSO prediction plume using the multi-model mean and the Gaussian standard error method summarizes the model consensus out to about 10 months into the future. The same cautions mentioned above for the distributional count of model predictions apply to this Gaussian standard error method of inferring probabilities, due to differing model biases and skills. In particular, this approach considers only the mean of the predictions, and not the total range across the models, nor the ensemble range within individual models.
In summary, the probabilities derived from the models on the IRI/CPC plume describe, on average, an even chance for ENSO neutral or minimal El Niño for May-Jul, followed by chances for El Niño rising to near 60% during late summer and fall. While chances for ENSO-neutral are not small for any of the seasons throughout the forecast period, chances for La Niña are very low throughout. A caution regarding this latest set of model-based ENSO plume predictions, is that factors such as known specific model biases and recent changes that the models may have missed will be taken into account in the next official outlook to be generated and issued in early June by CPC and IRI, which will include some human judgment in combination with the model guidance.

The forecast of a strong El Nino never made any sense and we discussed that a couple of months ago and that report can be accessed by clicking here. But now the latest forecast from NOAA has upped the probabilities a bit.

Here is the daily PDF and Spread Corrected version of the NOAA CFSv2 Forecast Model. It does not agree with the CPC-IRI analysis.

The estimated current value of the Nino 3.4 Temperature Anomaly after the adjustments have been applied is moving towards 0.6C or 0.7C for June which is an El Nino Value but it does not maintain that level into JJA. Looking ahead to Summer and Fall you see ENSO Neutral readings with a warm bias being the mean of the forecast ensemble. Moving into Winter the forecast is totally Neutral. But notice the wide spread among forecast members into the Fall and Winter. The forecasts have come down from a strong El Nino to what may be barely a near El Nino and most likely just ENSO Neutral. We discussed that recently in this article – click to read.

From Tropical Tidbits.com

The above is from a legacy “frozen” NOAA system meaning the software is maintained but not updated. It seems to show a cycle in the Nino 3.4 Index Values. I see that as I monitor the TAO/TRITON graphic. My best guess is that it is related to the MJO but it certainly is intriguing. I do not need to draw in the lines for you to see that the Nino 3.4 Index as reported by CDAS has moved above the 0C line and is now reporting a warm anomaly but not yet an increasing warm anomaly.

Forecasts from Other Meteorological Agencies.

Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)

Discussion (notice their threshold criteria are different from NOAA). Also the seasons in the Southern Hemisphere are the reverse of those in the Northern Hemisphere.

Tropical Pacific remains warmer than average
The El Niño–Southern Oscillation (ENSO) remains neutral. With the tropical Pacific Ocean warmer than average, and around half the international climate models reaching El Niño levels later in the year, development of El Niño in 2017 cannot be ruled out. The Bureau’s ENSO Outlook remains at El Niño WATCH, meaning there is around a 50% chance—double the normal likelihood—of El Niño developing in 2017.
Sea surface temperatures across the central tropical Pacific remained half a degree warmer than average over the past month. This is below the El Niño threshold of +0.8 °C. Further warming in the coming fortnight is unlikely, with trade winds forecast to be stronger than average. All other ENSO indicators are also neutral.
Five of eight international climate models suggest the tropical Pacific Ocean is likely to warm above El Niño thresholds during the second half of 2017. However virtually all models now suggest less warming is likely to occur compared to their previous outlooks, indicating any event may be weak. Models have lower accuracy forecasting El Niño during the autumn months, though accuracy begins to improve from June.
El Niño is often, but not always, associated with a drier than average winter–spring over eastern Australia. Even if El Niño thresholds are not met, Australia may still see some El Niño-like effects if waters in the tropical Pacific Ocean remain warm.

Here is the JAMSTEC forecast of the Nino 3.4 values which are the most looked at index used to forecast El Nino. This report was issued on May 8 or May 9.

This is the Discussion that goes with their May 1 Nino 3.4 forecast:

May 12, 2017
Prediction from 1st May, 2017
ENSO forecast:
A moderate-to-strong El Niño event is developing now in the tropical Pacific Ocean. The SINTEX-F model has consistently predicted the El Niño since December last year. The event is expected to reach its peak in boreal winter, and we expect negative sea level anomalies in Micronesia and Melanesia. The frequent occurrences of El Niños in recent years suggest a decadal turnabout in the tropical Pacific climate condition to El Niño-like state after a long spell of La Niña-like state. Such natural climate variability may double the global warming impact as we observed during the period from 1976 through 1998. We need to be prepared well to this possible decadal climate regime shift. [Editor’s Note: At GEI we are inclined to think it is more likely that there will be a need for another ENSO Cycle for the Pacific to change to its Positive Phase.]
Indian Ocean forecast:
All ensemble members of SINTEX-F now predict a rather strong positive Indian Ocean Dipole; the ensemble mean prediction suggests it to peak 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. We will observe co-occurrence of a positive Indian Ocean Dipole and an El Niño in the latter half of 2017; 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, while some parts of eastern Russia and northern Australia will experience a colder-than-normal condition in the boreal summer. In the boreal fall, most part of the globe also will be in a warmer-than-normal condition, while some parts of northern Europe, northern U.S. and southern Canada will be in a colder-than-normal condition in the boreal fall.
As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for most parts of Philippines, West Africa, and Mexico during the boreal summer, whereas most parts of Indonesia, Australia, India, eastern China, Korea, northern Brazil, and Peru will experience a drier condition during the boreal summer. In the boreal fall, most parts of Indonesia, Philippines, northern India, Australia, eastern China, the Far East, and southern Brazil will experience a drier-than-normal condition, while most parts of West Africa, southern Africa, East Africa, central India, and U.S. will be wetter-than-normal. Those are partly due to co-occurrence of the El Niño and the positive Indian Ocean Dipole. In particular, the drier condition in Indonesia and Australia will be augmented by the co-occurrence.
Most parts of Japan will be moderately warmer-than-normal and wetter (drier)-than normal over the western (northern) part in summer. In particular, we expect more (less) rain in the western (northern) Japan in the Baiu season. Our monthly picture (not shown) suggests that Japan might be covered by an equivalent barotropic high in summer, suggesting a hotter and drier condition. The drier condition may persist even in fall. El Niño influences may be canceled regionally owing to development of the positive Indian Ocean Dipole and vice versa.

On Saturday May 20 we released our analysis of the NOAA and JAMSTEC seasonal outlook updates. As anticipated there was a lot of disagreement in the further out months.

Indian Ocean IOD (It updates every two weeks)

The IOD Forecast is indirectly related to ENSO but in a complex way.

Discussion

Indian Ocean Dipole outlooks
The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 21 May was +0.33 °C.
Four of the six surveyed models indicate a positive IOD is likely to form during winter. However, model skill is low at this time of year, so caution should be exercised when using these forecasts.
A positive IOD typically brings below average winter-spring rainfall to parts of southern and central Australia.

Information on the impacts on Australia of the IOD can be found by clicking here. But Australia is not the only nation impacted by the IOD.

It is important to understand how and where 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 there is now interest as to whether or not this Summer and Fall will be El Nino situations. The models were suggesting this as a possibility but now it is not at all clear that an El Nino is coming. But it is still too soon to tell due to the Spring Predictability Barrier or SPB which is was explained at this link. But it should be clear by next month.

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.

JAMSTEC has raised the possibility of a Climate Shift in the Pacific and the implications of this are discussed in a prior GEI Weather and Climate Report which you can access by clicking here.

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. Parts of that discussion are in the beginning section of this week’s Report.

The odds of a climate shift for CONUS taking place has significantly increased. It may be in progress. JAMSTEC is suggesting that if there is an El Nino in the winter of 2017/2018 this could signify that the PDO has entered its Positive Phase. The AMO is pretty much neutral at this point (but more positive i.e. warm than I had expected) 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. JAMSTEC is suggesting it might occur very soon.

E. Relevant Recent Articles and Reports

Weather in the News

Shark!

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.

1. Introduction

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.

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.

Click for Source

Interaction between the MJO and ENSO

This Table is a first attempt at trying to relate the MJO to ENSO

Relationship of MJO and ENSO
	El Nino	La Nina	MJO Active Phase	MJO Inactive Phase
Eastern Pacific Easterlies	Weaker	Stronger Part of Decay Process	Counteracts Easterlies	Enhances Easterlies
Western Pacific Westerlies	Stronger May Create or Stimulate the Onset of El Nino via Kelvin Waves	Weaker Part of Decay Process	Strengthens Westerlies	Weakens Westerlies
MJO Active Phase	More likely Stimulates	Less likely and weak Retards development of a new La Nina	Stimulates the Jet Stream
MJO Inactive Phase	Less Likely Suppresses	More likely but weak Accelerates development of a new La Nina and the Decline of a mature La Nina		Slows the Jet Stream and can induce a Split Stream especially during a La Nina

Table needs more work. Is intended to show the interactions. What is more difficult is determining cause and effect. This is a Work in Progress.

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*	+	+

*The GEI Weather and Climate Report does not accept this as a legitimate La Nina. It is not unusual for different Meteorological Agencies to maintain different lists of El Ninos and La Ninas. This is usually because the criteria for classification differ slightly. Obviously the GEI Weather and Climate Report has no standing but nevertheless for any analysis we do, we will either not include or asterisk this La Nina to indicate that NOAA has it on their list and we consider that to be Fake News. The alternative is to conclude that the other Meteorological Agencies are not able to measuring things correctly. .

ONI Recent History

The Feb/Mar/Apr preliminary has just come out as +0.1. This means that we would still need five consecutive values of +0.5 or greater for this to be an El Nino and that is not going to happen. The full history of the ONI readings can be found here. The MEI index readings can be found here.

May 29, 2017 Weather and Climate Report – West to East Divide for CONUS

Donalditry Trumpovetsky

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May 29, 2017 Weather and Climate Report – West to East Divide for CONUS

Total

Portion in Nino 3.4 Measurement Area

WARM POOL

WARM POOL

0

0

WARM POOL

160E

0

0

160E

LAND

105

50

LAND

LAND

0

0

E. Relevant Recent Articles and Reports

F. Table of Contents for Page II of this Report Which Provides a lot of Background Information on Weather and Climate Science

G. Table of Contents of Contents for Page III of this Report – Global Warming Which Some Call Climate Change.

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.

Donalditry Trumpovetsky

Early Headlines: Asia Stocks Mixed, Dollar Flat, Oil Down, Gold Up, Senate Turf Wars Over Russia, Euro Crisis Fades, BA Massive Fail, Japan Labor Mkt Tight, North Korea Surprise, And More

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Early Headlines: Asia Stocks Mixed, Dollar Flat, Oil Down, Gold Up, Senate Turf Wars Over Russia, Euro Crisis Fades, BA Massive Fail, Japan Labor Mkt Tight, North Korea Surprise, And More

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