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posted on 16 May 2017

May 15, 2017 Weather and Climate Report - Excitement Builds

Written by Sig Silber

Come Thursday, the face off between NOAA and JAMSTEC will begin with Australia siding with NOAA. But it will take until Saturday for our report on the disagreements to be published. In the meantime, the Spring CONUS weather pattern remains unusually active and may somewhat resemble Winter in the West. So get out the skis. BTW, as we predicted last Monday, NOAA has reduced their level of confidence in there being an El Nino this Summer, Fall and Winter. Their full analysis is in the ENSO Section of our report.

weather.caption


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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. We can not discuss that tonight because NOAA has not yet released their updated Outlook which will be this Thursday. I am sure there are hints and we are reporting some of those hints tonight. 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.

Eastern Pacific Animation

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.

 Water Vapor Imagery

Tonight, Monday evening May 15, 2017, as I am looking at the above graphic, we see wet clouds across most of the Northern Tier and we see if we look carefully the LOW moving past Southern California. You can kind of see the cyclonic swirl of the clouds there. You also see clouds south of CONUS entering Texas.  The East Coast is clear.

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.

Current Jet Stream

One sees the current jet stream above. Notice the Jet Stream as it curls around Baja. And then there is New England.

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

 Center for Western Weather and Water Extremes, Scripps/UCSD.

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 what we saw on the above graphic re New England but more clearly. We also see another Pacific Storm approaching Oregon and Northern California. The Caribbean looks interesting also.

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.

current highs and lows

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.

Eastern Pacific Two Day Tropical Weather Outlook

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.

Day 3 Weather Forecast

The Aleutian Low is as I look at this Day 3 forecast is a unified low centered over the Aleutian Islands with central surface air pressure of 1004 hPa or is it a split low with a stronger part over by Kamchatka with a central pressure of 996 hPa or is it a giant trough?. The Aleutian Low is turning from a semi-permanent feature into a train of Lows which would one expects this time of the year. Remember this is a forecast for Day 3 not the current situation. The average sea level air pressure in the winter is 1001 hPa and 994 hPa for a non-split Low. We are almost out of the Fall/Winter/Spring pattern but according to current forecasts we are not out of it. This graphic changes every six hours.
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 way out to sea and has a central surface air pressure of 1028 hPa? There is thus now for Day 3 a block on Pacific Storms entering CONUS. We will see how this works out.
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.

Now looking at the 5 Day Jet Stream Forecast

Jet Stream Five Days Out .

This is a Day 5 forecast by one model.  Each day the Jet Stream seems to be forecast to be further south in five days. 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.

air pressure and altitude
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.

Short term forecasts

Here is the seven-day cumulative precipitation forecast. More information is available here.

Seven Day WPC Quantitative precipitation forecast

We see almost total coverage of CONUS excluding California and Arizona. The Plains States are fairly wet.

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.

7 Day 500 MB Geopotential Forecast

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 an East Central CONUS trough with two ridges one on the East Coast and one on the West Coast. The Low shown off the Coast of Baja may be significant. Could that turn into a Rex Block?
Remember this is a forecast for Day 7. Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. This week it looks like the 540 line will not impact CONUS but if there is a change it most likely would impact Maine. Thickness lines near or over 600 tend to suggest very warm temperatures. So that is what we will be focusing on now.

 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 May and three-month MJJ maps which are issued and updated less frequently than the first three maps shown.

Small Images of Temperature Maps
6 to 10 Days 8 to 14 Days Weeks 3 and 4
6 to 10 Day 8 - 14 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 15, 2017 was 4 out of 5)

6 - 10 Day Temperature Outlook

8 - 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on May 15, 2017 was 2 out of 5) 

8-14 Day Temperature Outlook

Looking further out.

Experimental Week 3-4 Temperature Outlook

Consolidation of 6 - 10, 8 - 14 and Experimental Week 3-4 Temperature Forecasts

Interpreted on May 15, 2017

May 22 to May 29 May 27 to June 9

Days 6 - 10: CONUS is warm in the West and in the East but cool in the Center. Alaska is warm.

The Northwest cool anomaly is from the coast to the north but extends to the Pacific in Northern California. 2/3rds of CONUS excluding New England is warm with the anomaly extending to the west into Arizona. Alaska remains warm. 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 deamplifies. Alaska remains warm to the North and in the Panhandle.
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.

 

Now for reference purposes, 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.

May Temperature Outlook Updated on April 30, 2017

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 and statistical models 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.

MJJ 2017 Temperature Outlook Issued on April 20, 2017

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 May  and three month MJJ maps which are issued and updated less frequently than the first three maps shown.

 Small Images of Precipitation Maps
  8 to 14 Day Weeks 3 and 4
6 to 10 Day 8 - 14 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 15, 2017 was 4 out of 5)

6 - 10 Day Precipitation Outlook

8 - 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on May 15, 2017 was 2 out of 5)

Current 8 - 14 Day Precipitation Outlook

Looking further out.

Weeks 3 and 4 Experimental Forecast..

Consolidation of 6 - 10, 8 - 14, and Week 3-4 Precipitation Forecasts

Interpreted on May 15, 2017

May 22 to May 29  May 27 to June 9, 2017
Days 6 -10: The Northwest of CONUS is dry with a second dry anomaly over the Dakotas. The Eastern half of CONUS is wet.  Alaska is wet west and south and down into the Panhandle.

For CONUS, the Southern dry anomaly is shifted west a bit from the prior forecast (recognizing we are now discussing a two week period of time that is one week later). It now covers SE Texas but does not reach the Atlantic Coast. There is a wet anomaly across the Northern Tier also shifted further west than forecast last week and for the current Week 3 - 4 forecast extends from Western Michigan to and beyond Idaho. For Alaska only a small area in the Extreme North 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 unlikely.

Week 2: Similar to Days 6 - 10 but New Mexico becomes dry as the wet anomaly shifts to the east. South Florida becomes EC. The Northwest CONUS dry anomaly extends north into part of the Alaskan Panhandle.

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.

 

Now for reference purposes 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.

May 2017 Precipitation Outlook Updated on April 30, 2017

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 and statistical models 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.

MJJ 2017 Precipitation Outlook Issued on April 20, 2017

Here is the NOAA discussion released today May 15, 2017.

6-10 DAY OUTLOOK FOR MAY 21 - 25 2017

TODAY'S MODEL SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE 500-HPA FLOW PATTERN PREDICTED OVER THE FORECAST DOMAIN. TROUGHS ARE INDICATED OVER THE EAST-CENTRAL CONUS, THE ALEUTIANS, AND NEAR SOUTHERN CALIFORNIA. A STRONG RIDGE IS FORECAST OFF THE PACIFIC NORTHWEST COAST EXTENDING NORTHWARD TO EASTERN ALASKA. ENSEMBLE SPREAD IS GENERALLY LOW OVER THE EASTERN HALF OF THE CONUS BUT MODERATE TO HIGH OVER THE REMAINDER OF THE FORECAST DOMAIN (PARTICULARLY OVER THE PACIFIC NORTHWEST AND ALASKA). TODAY'S MANUAL 500-HPA HEIGHT BLEND FAVORS TODAY'S GFS ENSEMBLE MEAN SOLUTIONS BASED ON CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST. 

BELOW NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE CENTRAL CONUS IN ASSOCIATION WITH A 500-HPA TROUGH FORECAST OVER THE EAST-CENTRAL CONUS. RIDGING AND ABOVE NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR THE WEST COAST OF THE CONUS AND MOST OF ALASKA. ABOVE NORMAL TEMPERATURES ARE ALSO LIKELY FOR THE EASTERN SEABOARD AHEAD OF THE TROUGH PREDICTED OVER THE EAST-CENTRAL CONUS.

ABOVE MEDIAN PRECIPITATION IS LIKELY FOR THE EASTERN THIRD OF THE CONUS AS WELL AS THE SOUTHERN PLAINS IN ASSOCIATION WITH THE TROUGH INDICATED NEAR THE MISSISSIPPI VALLEY. BELOW MEDIAN PRECIPITATION IS FAVORED FOR PARTS OF THE NORTHERN PLAINS BEHIND THE TROUGH AXIS. DYNAMICAL MODEL GUIDANCE AS WELL AS ANALOGS FROM THE MANUAL BLEND FAVOR ABOVE MEDIAN PRECIPITATION FOR PARTS OF THE CENTRAL ROCKIES. RIDGING AND ABOVE NORMAL HEIGHTS LEAD TO ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR THE NORTHWESTERN CONUS. ABOVE MEDIAN PRECIPITATION IS LIKELY FOR MUCH OF SOUTHERN ALASKA DUE TO A TROUGH AND ASSOCIATED SURFACE LOW FORECAST NEAR THE ALEUTIANS.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO FAIRLY GOOD MODEL AGREEMENT.  

8-14 DAY OUTLOOK FOR MAY 23 - 29 2017 

DURING THE WEEK-2 PERIOD, A MEAN TROUGH IS FORECAST TO PROGRESS TO THE EASTERN CONUS. THE RIDGE PREDICTED NEAR THE PACIFIC NORTHWEST DURING THE 6 TO 10 DAY PERIOD IS FORECAST TO PUSH INLAND AND DE-AMPLIFY  A WEAK TROUGH IS INDICATED FARTHER TO THE SOUTH NEAR THE CALIFORNIA COAST. RIDGING AND ABOVE NORMAL HEIGHTS ARE FORECAST TO REMAIN OVER MUCH OF ALASKA AHEAD OF A TROUGH OVER THE BERING SEA. ENSEMBLE SPREAD IS LOW TO MODERATE OVER THE EASTERN CONUS, MODERATE TO HIGH OVER THE WESTERN CONUS, AND VERY HIGH OVER THE HIGH LATITUDES. DUE TO HIGH MODEL SPREAD, TODAY'S WEEK-2 MANUAL 500-HPA BLEND CONSISTS ALMOST ENTIRELY OF THE ENSEMBLE MEAN SOLUTIONS.

BELOW NORMAL TEMPERATURE PROBABILITIES ARE ENHANCED FOR MUCH OF THE CENTRAL AND EASTERN CONUS DUE TO A FORECAST TROUGH AND ASSOCIATED BELOW NORMAL HEIGHTS. ABOVE NORMAL TEMPERATURES ARE FAVORED AHEAD OF THE TROUGH AXIS FOR FLORIDA AND PARTS OF THE SOUTHERN ATLANTIC COAST. THERE ARE INCREASED ODDS FOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WESTERN CONUS, ALASKA, AND PARTS OF SOUTHERN TEXAS DUE TO RIDGING AND/OR ABOVE NORMAL HEIGHTS. 

MEAN SOUTHERLY FLOW IN THE LOW LEVELS, AHEAD OF A SURFACE LOW OVER THE BERING SEA, FAVORS ABOVE MEDIAN PRECIPITATION FOR MUCH OF SOUTHERN ALASKA. ABOVE MEDIAN PRECIPITATION IS ALSO LIKELY FOR THE EASTERN THIRD OF THE CONUS AS WELL AS PARTS OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY DUE TO TROUGHING AND NEAR TO BELOW NORMAL HEIGHTS. SUBSIDENCE BEHIND THE MEAN TROUGH AXIS LEADS TO ENHANCED PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR PARTS OF THE NORTHERN PLAINS. BELOW MEDIAN PRECIPITATION IS INDICATED FOR THE NORTHWESTERN CONUS DUE TO RIDGING AND ABOVE NORMAL HEIGHTS. CONVERSELY, ABOVE MEDIAN PRECIPITATION IS SLIGHTLY FAVORED FOR PARTS OF THE CENTRAL ROCKIES CONSISTENT WITH GEFS REFORECAST GUIDANCE. 

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO HIGH MODEL SPREAD (PARTICULARLY OVER THE HIGH LATITUDES).

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON MAY 18

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 20, 1960 Neutral + +  
May 21, 1960 Neutral + +  
May 3, 1994 La Nina - -  
May 7, 1977 Neutral + -  
May 16, 1964 Neutral + -  
Apr 24, 2003 Neutral + +  
Apr 25, 2003 Neutral + +  
Apr 30, 2008 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 April 24 to May 21 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 8. These analogs are centered on 3 days and 4 days ago (May 11 or May 12). So the analogs could be considered to be a bit out of in sync with the calendar meaning that we will be getting weather that we would normally have a few days earlier in the year. The question is what if anything does this mean. I think in this case it means something with a winter storm coming in. For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are six ENSO Neutral Analogs, zero El Nino Analogs, and two La Nina analogs. Looks like the analogs are signaling ENSO Neutral. The phases of the ocean cycles of the analogs are consistent with McCabe Condition C which is the Northern Tier and Mid-Atlantic Drought scenario. So we will see if the Mid-Atlantic turns out wet as forecast.

The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. Water Planners might usefully pay attention to the low-frequency cycles such as the AMO and the PDO as the media tends to focus on the current and short-term forecasts to the exclusion of what we can reasonably anticipate over multi-decadal periods of time. One of the major reasons that I write this weather and climate column is to encourage a more long-term and World view of weather.

McCabe Maps modified to include the subtitles

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 Conditions from 2007 report with labels corrected with authors permission

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 6, 2017

May 6  2017  30 Day temperature and precipitation departures.

Re Precipitation the most noticeable change is how dry Arizona has been. Re Temperature, the warm anomaly continues to moderate. 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 13, 2017

May 13, 2017 30 Day Temperature and Precipitation Departures

Both the Temperature and Precipitation anomalies are more muted than last week. Remember this is a 30 day average meaning seven most recent days are added and seven most distant days are removed.

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

Same as above but for July

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 in the middle of May right now so we are 2/3rds between the two set of positions shown above for January and July.

Todays Forecast

Temperature at 2 Meters

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. Northern Eurasia is quite cool. The Antarctic is warm.

Maine Reanalyer

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.

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

BOM World Preciptation  Wednesday

Notice than Northern South American remains wet.

Temperature

BOM Current Temperature Wedensday

The Northern Africa, Arabian Peninsula, and India remain warm.

Looking Out a Few Months

Here is the new precipitation forecast from Queensland Australia:

Rising  SOI  forecast for May to July 2017.

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

Last month, JAMSTEC issued their ENSO forecasts and climate maps in early April. We issued a Special Update on April 22 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 an Update on May 20 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.

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]

Daily SST Anomalies

First the categorization of the anomalies.

Mediterranean, Black Sea and Caspian Sea Western Pacific West of North America East of North America North Atlantic
Black Sea slightly cool. Caspian warm and Mediterranean neutral to slightly warm. Red Sea and Persian Gulf are warm. Neutral to slightly warm but an intense cool area just west of the Dateline. Cool in Bering Straights. Warm Neutral
The Tropical Pacific

Neutral to slightly warm

Africa West of Australia South and East of Australia West of South America East of South America
Warm off Northwest Africa. Cool Gulf of Guinea along the Coast. The Arabian Sea is slightly warm. Cool Slightly warm Southeast Neutral to 30S then warm Warm    south of 30S.

 

What you see in the below graphic is the change in the anomaly over the last four weeks. So you have to refer to the graphic above this one to really interpret this 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.

May 15, 2017 four week change is SST Anomalies

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

Mixed picture except the Red Sea continues to warm.

Cooling around  Japan. Warming   especially around the Philippines. Warming in Bering Straits. Warming north of 20N, Cooling in Gulf of Mexico Warming off of NW Africa.
The Tropical Pacific Warming west, much cooling east, slight warming in Nino Measurement Area. Does not look like an El Nino at all.
Africa West of Australia South and East of Australia West of South America East of South America
Warming in Arabian Sea. Warming off Northwest coast. Cooling off of Southeast Coast and  east of Madagascar. Cooling in the north. Warming to the west. Cooling east including north of New Zealand. Slight warming off of Peru. Cooling

 

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 +0.18 +0.0
April +0.52 NA +.02

 

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

Tropical Hazards

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 15 for what is shown as Week Two, the period May  17, 2017 to May 23, 2017, we see dry conditions for Southern India* and wet conditions for parts of Cuba, Brazil and Equatorial Africa*.
* 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.

Western Pacific Tropical Activity

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.

Current SST and wind anomalies

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

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

170E

0

0

These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly (warmish neutral)*

170E

130W

60

40

0C or cooler Anomaly (coolish neutral)

130W

LAND

35

10

 

* A warm anomaly exceeding +0.5C is showing South of the Equator in today's TAO/TRITON Five-Day Mean Graphic. But it is not quite along the Equator which is what we are showing in the above graphic.

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 15, in the afternoon working from the May 14 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 +0.5 +0.4
B. 160W to 150W +0.4 +0.5
C. 150W to 140W +0.4 +0.5
D. 140W to 130W +0.4 +0.8
E. 130W to 120W +0.5 +0.5
Total +2.2 +2.7
Total divided by five i.e. the Daily Nino 3.4 Index (+2.2)/5 = +0.4 (+2.7)/5 = +0.5

 

My estimate of the daily Nino 3.4 SST anomaly tonight is +0.5.  NOAA has again reported the weekly Nino 3.4 to be +0.5 which is a marginal El Nino Value. My calculations came out higher this week because some warmer water south of the Equator intruded into the somewhat less warm water north of the Equator and formed a pod of slight warmer water. This represented approximately a 0.1C increase in the Nino 3.4 calculation.
Nino 4.0 is reported a bit higher this week at +0.4. 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 slightly higher at +1.0. I believe it was up there close to 3 at one time so this index has been fluctuation quite a bit and is what fooled the models and the meteorologists earlier this year.
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.

May 15, 2017 Nino Readings

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.

May 15, 2017 Equatorial Pacific SST Anomalies

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. This is possibly the beginning of an El Nino pattern. But week to week there have been no substantial changes. If anything the pattern is fairly stable. Basically there is on balance no change from last week.
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.

May 15, 2017 Upper Ocean Heat Anoma

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 last week presumably to be ready to draw in a downwelling wave soon. And you can see that there is warm water further east this week at 160W. Soon we may see that NOAA has drawn in a Kelvin Wave. Two years there were five or six Kelvin waves the first ones quite strong.This is showing at 0.5C to 1.0C. So that is kind of a range of strength that an El Nino might have if formed. It is strange to see the water having moved to the east at the same time the Easterlies have strengthened. It may be a question of the timing of the data in the different graphics.

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). 

.May 15, 2017 Kelvin Wave Analysis.

The pattern has not changed much 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 much change. There is no indication of an El Nino 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]. Further east the Warm Anomaly at depth has continued to shrink. In all cases involving anomalies we are dealing with variations from what is considered normal. And that definition of normal includes seasonal variation and of course variation by depth. So one wonders when looking at this subsurface warm water just west of the Dateline, has it gotten warmer or is it statistical artifact? If it has gotten warmer how exactly did that happen? 

Now for a more detailed look. Notice by the date of the graphic (dated May 8, 2017) that the lag in getting this information posted so the current situation may be a bit different than shown. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.

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.

Subsurface Heat Anomalies

Re the top graphic, let us first look at surface temperature anomalies. Warm water continues to extend from the Coast of Ecuador to 100W and pockets of slightly warm water all the way to 130W with another small pocket of warm water at 150W. Subsurface Temperature Anomalies: The cool water is still there but further east and the anomaly is dissipating. Notice the warm water at depth but there is a big gap east of 160W. There has been hardly any change recently from report to report which are each approximately five days apart. So there is basically no change from last week. But the overall pattern seems to be converging on ENSO Neutral. There is one very warm pocket of water just west of the Dateline at 150 meters. At some point it is likely to rise in the Nino 3.4 Measurement Area can create El Nino Conditions for a few months. But that is not sufficient to have any reputable meteorologist conclude that we had had an El Nino.

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 170W. 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 now extends all to the way to Ecuador. 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 175E, 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. 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 175E in the bottom graphic. You can see the dip 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.

Equatorial Temperature Simulation

Isotherm Simulation

And now Let us look at the Atmosphere.

Low-Level Wind Anomalies near the Equator

Here are the low-level wind anomalies.

Low Level Wlind 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. 

OLR Anomalies Along the Equator

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)

Here is the NOAA Weekly prettied version. Same data same source. Above is the auto-update version which updates daily. Below is the frozen version with NOAA Commentary. That is the only difference. For me it means one more graphic to upload so I usually do not provide it. The one above updates without me doing anything. Less attractive but more efficient for me.

May 15, 2015 OLR analysis.

It is a lot easier to interpret it this way as NOAA has circled the areas of interest. The pattern has changed to no pattern. Welcome to ENSO Neutral.

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 15 was reported as -8.31 which is a marginal El Nino value. The 90 Day Average was reported at -4.72 which is ENSO Neutral but dropping into El Nino territory.  Looking at both the 30 and 90 day averages is useful and both are in agreement that we are in ENSO Neutral but trending towards El Nino. It is probably temporary as for a month or two.

 

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-April (April 20) 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.

May 11, 2017 CPC/IRI Update two graphics side by side.

First we look at graphic on the right which is the IRI/CPC Model-Based Report issued on April 13, 2017. Then we look on the left at the most recent (May 11) what I call the Tea Leaves Report as it is not clear how this report is prepared as it is some combination of model results and opinions of meteorologists and it is just not possible to really know how this report is prepared. Notice the new report has much lower probabilities for El Nino than the prior report which is what we predicted would happen.

We had thought that the NOAA Update was due on May 18  but that was incorrect as it was issued on May 11 and here it is. The Official Version with graphics can be found here.

Published: May 11, 2017

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: Not Active

Synopsis: ENSO-neutral and El Niño are nearly equally favored during the Northern Hemisphere summer and fall 2017.

ENSO-neutral persisted during April, with near-average sea surface temperatures (SSTs) observed across the central equatorial Pacific and above-average SSTs in the eastern Pacific (Fig. 1). The latest weekly Niño index values were +0.5°C in the Niño-3 and Niño-3.4 regions, and +0.3 and +0.8°C in the Niño-4 and Niño-1+2 regions, respectively (Fig. 2). The upper-ocean heat content anomaly was slightly positive during April (Fig. 3), reflecting the strengthening of above-average temperatures at depth around the Date Line (Fig. 4). Atmospheric convection anomalies were weak over the central tropical Pacific and Maritime Continent (Fig. 5), while the lower-level and upper-level winds were near average over most of the tropical Pacific. Overall, the ocean and atmosphere system remains consistent with ENSO-neutral

Most models predict the onset of El Niño (3-month average Niño-3.4 index at or greater than 0.5°C) during the Northern Hemisphere summer (Fig. 6). However, the NCEP CFSv2 and most of the statistical models are more conservative and indicate that while Niño-3.4 index may be near or greater than +0.5°C for several months, the warmth may not last long enough to qualify as an El Niño episode (5 consecutive overlapping seasons) and/or may not significantly impact the atmospheric circulation. Relative to last month, the forecaster consensus reflects slightly lower chances of El Niño (~45%), in part due to the conflicting model guidance and lack of a clear shift toward El Niño in the observational data. In summary, while chances are slightly lower than 50%, ENSO-neutral and El Niño are nearly equally favored during the Northern Hemisphere summer and fall 2017 (click CPC/IRI consensus forecast for the chance of each outcome for each 3-month period).

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA’s National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Forecasts are also updated monthly in the Forecast Forum section of CPC’s Climate Diagnostics Bulletin. Additional perspectives and analysis are also available in an ENSO blog.

The next ENSO Diagnostics Discussion is scheduled for 8 June 2017.

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.

Here is the daily PDF and Spread Corrected version of the NOAA CFSv2 Forecast Model.

CFSv2 spread and bias correct ENSO forecast

The estimated current value of the Nino 3.4 Temperature Anomaly after the adjustments have been applied is an ENSO Neutral Value now with a warm bias almost reaching El Nino values but not forecast to shoot higher. Looking ahead to summer you see ENSO Neutral readings being the mean of the forecast ensemble. But this forecast is still before the end of the Spring Prediction Barrier which means we need to wait until the end of May [click here to understand why] before having a high degree of confidence in the various models. 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 an El Nino if at all. We discussed that recently in this article - click to read.

From Tropical Tidbits.com

CDAS Legacy System

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)

Australia POAMA ENSO model run

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.

Models reduce likelihood of El Niño for 2017 but tropical Pacific Ocean warmer than average

The tropical Pacific is currently El Niño–Southern Oscillation (ENSO) neutral. Despite the likelihood for El Niño easing in some models, an event in 2017 cannot be ruled out. The Bureau's ENSO Outlook remains at El Niño WATCH, meaning there is around a 50% chance that El Niño may develop in the coming months.

Sea surface temperatures in the tropical Pacific Ocean have warmed since the start of the year, but remain below El Niño thresholds. Some other atmospheric indicators have shifted over the past fortnight, but also remain below El Niño levels.

Some international climate models have reduced the likelihood of El Niño this year. However, five of eight international climate models still indicate the tropical Pacific Ocean may exceed El Niño thresholds during the second half of 2017. It should be noted that models have lower accuracy forecasting El Niño through the autumn months.

El Niño is often, but not always, associated with a drier than average winter-spring over eastern Australia. Of the 27 El Niño events since 1900, 18 have resulted in at least some areas of significantly dry conditions for Australia.

The Indian Ocean Dipole (IOD) remains neutral. Four out of six climate models suggest a positive IOD is likely to develop during winter. Generally, when a positive IOD coincides with El Niño, the pattern of below average rainfall extends further west than it typically would under El Niño alone.

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.

JAMSTEC May 1, 2017 ENSO Forecast.

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 will be releasing our analysis of the NOAA and JAMSTEC seasonal outlook updates. I already have the JAMSTEC information and will receive the NOAA information on Thursday May 18. There will be a lot of disagreement.

Indian Ocean IOD (It updates every two weeks)

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

IOD POAMA Model Run

Discussion

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 7 May was +0.3 °C.

Current outlooks suggest a neutral IOD for the end of autumn, with some models indicating a positive IOD may form later in winter or spring. The Bureau's model POAMA predicts that the IOD will stay neutral for the remainder of the year.

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 Measurement Regions

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

Nothing to report

Weather Research in the News

Nothing to report

Global Warming in the News

U.S. Signs Fairbanks Declaration

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.

El Nino Zones

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.

Western Pacific Warm Pool

Click for Source

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
Relationship of MJO and ENSO
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

ONI History Updated on May 8, 2017

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.

Click here for a list of Sig Silber's Weather Posts

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