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posted on 11 April 2017

April 10, 2017 Weather and Climate Report - Zonal Flow i.e. Northern Storm Track

Written by Sig Silber

Updated April 13 at 4:20 pm EDT to reflect the passing of the threat to Australia

Australia appears to be dodging the Cyclones coming at it from the north. That does not mean that other nations and islands off of Australia will not be impacted but it seems that high population areas will be spared this week. For CONUS, the meridional pattern that has existed for many weeks may be changing to a more zonal pattern bringing the storm track across the Northern Tier.

weather.caption


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Watching the activity around Australia:

Australia Cyclone Activity

The latest information with more detail can be found by clicking here.

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 April 10, 2017, as I am looking at the above graphic, we see mostly storm activity associated with moist air being drawn in from the Gulf of Mexico and also Northern Tier storms related to Pacific Moisture.

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.

Current Jet Stream

One sees the current jet stream above. Notice it is less meridional (waves from north to south to north over and over again) and more progressive or zonal (with a more pure westerly orientation..

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.
Mostly this evening we see the moisture drawn in from the Gulf of Mexico.

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.

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 split low with one center located very far south of the Gulf of Alaska (and thus may not really be considered part of the Aleutian Low complex) with central surface  air pressure of 1000 and which appears to be moving on shore. There is another center beyond Kamchatka with central surface pressure that I can not read because the gradients are so close together but clearly very strong. 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. This graphic changes every six hours.
The High Pressure off of the West Coast, the familiar RRR, on Day 3 is back but pushed on Day 3 out to sea. The surface air pressure for this High is 1024 hPa. It is not clear exactly how this formation functions but there is no block on Day 3 to Pacific Storms entering CONUS or Canada from the Pacific. That may change very quickly after Day 3.
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 .

You can see that moisture is forecast to continue to stream into the West Coast and entering fairly far north and being quite zonal.  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 again a forecast for substantial precipitation along the Northern West Coast. There is also plenty of moisture in Central CONUS. This has the potential for a lot of violent weather and flooding. The graphic shows the cumulative precipitation over a seven-day period.

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. Remember that 540 relates to sea level. 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 a Western Trough, Central Ridge and perhaps an East Coast Trough. The features are not very pronounced as I am looking at the graphic this evening. .
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.

 Four- Week Outlook

Census Bureau Regions and Sub-Regions are not always the best way to describe weather patterns but I am showing this map as I may sometimes use their terminology  to describe regions.

Census Bureau  Regions

I have changed my approach at the suggestion of a reader. I will first present the 6 - 10 Day and 8 - 14 Day Maps and the Week 3 -  4 Experimental Outlook. Then for reference purposes I will show first the Updated Outlook for the single month of April followed by the three-month AMJ Outlook,  The prior approach was to first provide the One Month and Three-Month maps for reference purposes and then the three more recently issued forecasts made by dynamical models. The new approach is to present the information in the sequence of the time frame to which the forecast applies. 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 April and three month AMJ 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 April 10, 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 April 10, 2017 was 3 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 Forecasts

Interpreted on April 10, 2017

April 16 to April 24 April 22 to May 5

Days 6 - 10: The period starts cool in the Northwest and very warm for 3/4ths of CONUS except for New England which is cool. Alaska is mostly warm.

Alaska including the Panhandle is warm. Extreme CONUS West is cool. Almost 2/3rds of CONUS is warm from the East Coast westward and extending more to the west in the South and the North. Unlike last week, 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.
Week 2:  As the period evolves, the CONUS warm anomaly shifts to the south.
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.

April Temperature Outlook updated on March 31, 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.

AMJ 2017  Temperature Outlook Issued on March 16, 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 April and three month AMJ 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 April 10, 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 April 10, 2013 was 3 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 Forecasts

Interpreted on April 10, 2017

April 16 to April 24  April 22 to May 5, 2017
Days 6 -10  Alaska and the Panhandle are dry. CONUS is mostly wet except for the Southeast and Southwest which are dry.

Most of Alaska but not including the Panhandle is dry. The East Coast except New England and extending west to the Mississippi River is projected to be dry. A swath of the Northern Tier extending into the Great Lakes west to and including most of Idaho is projected to be wet. Unlike last week, 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 except for the Southeast.

Week 2: The dry anomalies gradually become EC.

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.

April  2017   Precipitation Outlook Updated on March 31, 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.

AMJ 2017 Precipitation Outlook Issued on March 16, 2016

Here is the NOAA discussion released today April 10, 2017.

6-10 DAY OUTLOOK FOR APR 16 - 20 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. A TROUGH IS FORECAST ALONG THE WEST COAST OF THE CONUS, WHILE MODELS FORECAST A RIDGE OVER THE CENTRAL AND EASTERN CONUS, SOUTHWESTERN CANADA AND ALASKA. TODAY'S MANUAL 500-HPA HEIGHT BLEND INDICATES NEGATIVE HEIGHT ANOMALIES OVER THE NORTHWESTERN PARTS OF THE CONUS AND POSITIVE ANOMALIES OVER ALASKA AND MOST OF THE SOUTHERN AND CENTRAL-EASTERN CONUS. 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.

BELOW NORMAL TEMPERATURES ARE MOST LIKELY FOR THE NORTHWESTERN CONUS DUE TO BELOW-NORMAL HEIGHTS. ABOVE NORMAL TEMPERATURES ARE PREDICTED FOR MOST OF THE REMAINING REGIONS OF THE CONUS, WHERE HEIGHT ANOMALIES ARE EXPECTED TO BE POSITIVE UNDER A FORECAST RIDGE. FOR MAINE, BELOW NORMAL TEMPERATURES ARE INDICATED BY THE ECMWF BASED TEMPERATURES TOOLS. CALIBRATED REFORECAST TEMPERATURE TOOLS FROM RECENT ENSEMBLE SOLUTIONS FAVOR BELOW NORMAL TEMPERATURE FOR EASTERN ALASKA, AND ABOVE NORMAL TEMPERATURES FOR WESTERN ALASKA.

NEAR TO ABOVE MEDIAN PRECIPITATION IS MOST LIKELY FOR THE WESTERN CONUS, AHEAD OF PACIFIC FLOW. PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ARE ENHANCED FROM THE SOUTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY, THE GREAT LAKES, AND THE NORTHEAST, ASSOCIATED WITH NORTHWARD FLOW OF MOISTURE FROM THE GULF OF MEXICO. POSITIVE 500-HPA HEIGHT ANOMALIES AND RIDGING ENHANCE PROBABILITIES FOR NEAR TO BELOW MEDIAN PRECIPITATION FOR PARTS OF THE SOUTHEAST. BELOW MEDIAN PRECIPITATION IS FAVORED FOR ALASKA IN ASSOCIATION WITH PREDICTED RIDGING AND POSITIVE 500-HPA HEIGHT ANOMALIES. BELOW MEDIAN PRECIPITATION IS FORECAST FOR COLORADO AND PARTS OF NEW MEXICO, WHICH IS CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS.

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

8-14 DAY OUTLOOK FOR APR 18 - 24 2017 

ENSEMBLE MEAN FORECASTS FOR THE WEEK 2 PERIOD INDICATE A TROUGH EXTENDING FROM SOUTH OF THE ALEUTIAN ISLANDS SOUTHWARD AND EASTWARD ALONG THE PACIFIC COAST OF NORTH AMERICA. A RIDGE AND POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST OVER THE SOUTHERN AND EASTERN CONUS AND ALASKA, WHILE WEAK NEGATIVE 500-HPA HEIGHT ANOMALIES ARE EXPECTED FOR THE NORTHWESTERN CONUS. 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.

THE RESULTING TEMPERATURE OUTLOOK IS VERY SIMILAR TO THAT FOR THE 6-10 DAY PERIOD. BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE NORTHERN AND NORTHWESTERN CONUS, WHILE ABOVE NORMAL TEMPERATURES ARE FAVORED FOR WESTERN ALASKA, AND SOUTHERN AND CENTRAL PORTIONS OF THE CONUS. BELOW NORMAL TEMPERATURES ARE FORECAST FOR EASTERN ALASKA, WHICH IS SUPPORTED BY THE CALIBRATED REFORECAST TEMPERATURE TOOL FROM GFS ENSEMBLE FORECASTS.

AREAS OF ENHANCED PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION ARE INDICATED FOR MOST OF THE WESTERN AND CENTRAL LOWER 48 STATES, AHEAD OF TROUGHING ALONG THE WEST COAST OF THE CONUS. ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ARE ALSO INDICATED FOR THE SOUTHERN PLAINS EXTENDING TO THE LOWER MISSISSIPPI VALLEY, THE GREAT LAKES, AND THE NORTHEAST, DUE TO THE PREDICTED INFLOW OF MOISTURE FROM THE GULF OF MEXICO. THAT IS CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE MEMBERS. BELOW MEDIAN PRECIPITATION IS MOST LIKELY OVER ALASKA UNDER THE PREDICTED RIDGE. 

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE TO GOOD AGREEMENT AMONG THE MODEL SOLUTIONS OFFSET BY SOME DISAGREEMENTS AMONG THE FORECAST TOOLS.

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.

Day

ENSO

Phase

PDO AMO

Other Comments

Apr  2, 1958 El Nino + + Probably a Modoki
Apr  6, 1980 Neutral + +(t) Right after a Modoki Type II
Apr 7, 1980 Neutral + +(t) Right after a Modoki Type II
Mar 28, 1983 El Nino + N Late in a strong El Nino
Mar 28, 1983 El Nino + N Late in a strong El Nino
Apr 2, 1991 Neutral - - Just before a Modoki
Apr 9, 1995 El Nino + + Tail end of a Modoki
Apr 15, 1996 La Nina + N Lull in a two-part La Nina
Apr 16, 1996 La Nina + N Lull in a two-part La Nina
Apr 20, 1996 La Nina + N Lull in a two-part 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 March 28 to April 20 which is 23 days which is a fairly tight tight spread but larger than last week. 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 April 9. These analogs are centered on 3 days and 4 days ago (April 6 or April 7). So the analogs could be considered to be out of sync with the calendar meaning that we will be getting weather that we would normally get three or four days later in the calendar. That is the opposite of the case last week.

For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are four El Nino Analogs, three ENSO Neutral Analogs and three La Nina analogs. Many of the analogs are duplicates in that they occurred very close to each other.  Looks like the analogs are signaling indecision. The phases of the ocean cycles of the analogs point clearly to McCabe Condition C which is totally opposite the 6 to 10 Day Forecast. This is confusing because the pattern in the Pacific is consistent with the forecast so I do not know what to make of that.

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 April 1, 2017

April 1, 2017  30 Day temperature and precipitation departures.

The Southern Tier drought is much less pronounced. The temperature anomalies are somewhat similar but the cool anomaly in the Northeast is much more pronounced. Remember this is a 30 day average with 7 more recent days added and 7 more distant days removed so it changes slowly.

And the 30 Days ending April 8, 2017

April 8, 25, 2017 30 Day Temperature and Precipitation Departures

Southeast drought letting up. Southwest drought intensifies into Mexico. Temperature patterns stable. Remember seven recent days are added and seven more distant days are removed so a 30 day average changes slowly.

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 graphic regularly as it really helps with understanding why things are happening the way they are.  I am trying to find the versions of the above that vary my month.

Todays Forecast

Temperature at 2 Meters

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. CONUS East Coast being warmer than normal is a highlight of today's forecast from this source. Europe is also warmer than normal.

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 India which impacts a large number of people. 

Additional Maps showing different weather variables can be found here.

Near Term (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 the wet belt along the Equator. Northern South America is wet. A large and intense low pressure system dominates the Western Northern Pacific.

Temperature

BOM Current Temperature Wedensday

It is projected to be hot in much of Africa and India and Indochina. That is a pretty dark red for India. Parts of Africa and the Arabian Peninsula are also very warm.

Looking Out a Few Months

Here is the new precipitation forecast from Queensland Australia:

Rising  SOI  forecast for April to June 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.  .

JAMSTEC Forecasts

JAMSTEC issued their ENSO forecasts and climate maps on March 15. We published a special Update Report on Saturday Night March 18 which can be accessed 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.

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 Neutral, Mediterranean and Caspian slightly warm Cool except west of Japan and east of Siberia in Bering Sea Cool Mid-Latitude, Slightly Warm of Baja Warm but just along the coast Warm
The Tropical Pacific Neutral with warmish bias
Africa West of Australia South and East of Australia West of South America East of South America
Warm off West Africa, cool south of Africa, warm east of Madagascar Cool Cool South, warm Southeast Fairly Neutral Warm south of Rio de Janeiro

 

What you see in the below graphic is the change in the anomaly over the last four weeks. So blue means either cooler or less warm. Red means warmer or less cool. 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. It is a bit like the graphic above is the first derivative of the sea surface temperature (SST) and the graphic below is the second derivative of the sea surface temperature(SST) but not exactly. Derivatives are the rate of change and what we have here in the above graphic is the delta between the current temperature and normal temperature and then in the graphic below we have the four-week change in the delta. It is a bit similar to derivatives where the first derivative is the rate of change and the second is the rate of acceleration of the change.

April 10, 2017 four week change is SST Anomalies

The categorization of the four week change in the anomalies.

Mediterranean, Black Sea and Caspian Sea Western Pacific West of North America East of North America North Atlantic
Eastern Mediterranean warming Cooling Little changed west of Central America cooling slightly Cooling Cooling
The.Tropical Pacific Cooling west, warming central, cooling east
Africa West of Australia South and East of Australia West of South America East of South America
Slightly warming west, cooling east of Madagascar, warming north and into Red Sea cooling west and southwest Little change but warming Northeast of New Zealand Dramatic cooling warming south of 40S and cooling off of Uruguay

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

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 April 10 for what is shown as Week Two, the period April 12, 2017 to April 18, 2017, wet conditions* for the Maritime Continent with a small area of tropical cyclone activity* in Northwest Australia and just off the Northeast corner of Australia and dry conditions* in parts of Brazil.
* 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.

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

Warm Pool

Warm Pool

0

0

+0.5C to +1C

130W

LAND

35

10

These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly

145W

130W

15

15

0C or cooler Anomaly

Dateline

145W

35

25

 

 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 April 10, in the afternoon working from the April 9 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 +0.1 0.0
B. 160W to 150W +0.3 0.0
C. 150W to 140W +0.5 +0.2
D. 140W to 130W +0.7 +0.7
E. 130W to 120W +0.9 +0.9
Total +2.5 +1.8
Total divided by five i.e. the Daily Nino 3.4 Index (+2.5)/5 = +0.5 (+1.8)/5 = 0.4

 

My estimate of the daily Nino 3.4 SST anomaly is +0.4 which is ENSO Neutral but on the Warm Side of Neutral. NOAA has again reported the weekly Nino 3.4 to be an ENSO Neutral value at +0.3 which is on the Warm Side of Neutral but the same as last week.
Nino 4.0 is also reported the same as last week at 0.0.. Nino 3 is also the same as last week at 0.8. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported much much cooler at +0.9 which is still a high value.
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. 

April 10, 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.

April 10, 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.
You can see that the cool anomaly (bottom of the Hovmoeller has vanished with no blue in the Nino 3.4 Measurement Area), some white and now quite a bit of light yellow (still ENSO Neutral but on the warm side) and El Nino-ish dark yellows off and on from 155W east and browns from 120W east but the reds are no longer showing at the bottom of the chart. However this lukewarm pattern weakened again last week but has spread out further west and from the west expanded a bit to the east. 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 change. If anything the pattern is fairly stable. Further west the surface is less warm. 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.

April 10, 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 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.

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). 

.April 10, 2017 Kelvin Wave Analysis.

Usually we use this to track Kelvin Waves but you can see the progression of warm water streaming east but not very much of it. Hard to conclude that warm water is moving subsurface to the East with that blue cool blob 165W to 145W. The reason this is important is what is called the Bjerknes Feedback Mechanism which you can read about here. It is an intricate set of interactions which determines the ENSO Cycle. Of course Jacob Bjerknes the son of the world renowned Norwegian meteorologist Vilhelm Bjerknes developed his theories in the sixties. There have been many modifications/improvements in his theories since then and this process continues. 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.

Now for a more detailed look. Notice by the date of the graphic (dated April 3, 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. The -1C water no longer shows anywhere. We only see -0.5 C water now from 170E to the Dateline which is west of the Nino 3.4 Measurement Area and a small blip from 170W to 165W. On the other hand, warm water continues to extend from the Coast of Ecuador to 115W and slightly warm water all the way to 130W. Subsurface Temperature Anomalies: The cool water is almost all gone. Notice the warm water at depth but there is a big gap between the 175W and 110W.

The bottom half of the graphic (Absolute Values which highlights the Thermocline) is now more useful as we track the transition to and ENSO Cool Event which may possibly become and El Nino.

It shows the thermocline between warm and cool water. The 28C Isotherm is now located at 160E. 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 170W. 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 being increasingly depressed by warm water all the way to Ecuador. We are seeing the great swap where neutral and even warm water replaces the cooler water at the surface.
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.

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

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

OLR Anomalies Along the Equator

There is not much week to week change in the pattern.

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 April 10  was reported as +3.03 which is ENSO Neutral. The 90 Day Average was reported at -1.33 which is about as Neutral as an SOI reading can be. 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 Mid-March and early-month report 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 the IRI/CPC March 16, 2017 fully model-based report.

March 16, 2017, 2016 Model Based ENSO Forecast

Here is the one week earlier what I call the "Tea Leaves Report" issued on March 9, 2017. I call it 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.

March 9, 2017 CPC/IRI Model Probability Report.

Notice that in one week the probabilities for an El Nino soared. Look at JAS as an example. On March 9th the Tea Leaves concluded that the chances of an El Nino were ever so slightly greater than the chances of ENSO Neutral. But one week later, the readers of the Tea Leaves looked at their model results and concluded that El Nino was an overwhelming favorite for JAS. That does not make any sense.

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

CFSv2 spread and bias correct ENSO forecast

Forecast with 0.5C drawn in.

The above is the April 7, 2017 forecast frozen (I thought it might have more resolution than the daily graphic but not so much. It will not auto-update) and I drew in the 0.5C El Nino Condition Threshold. 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 and shooting higher rapidly this month. Looking ahead to next summer you see El Nino readings being the mean of the forecast ensemble but it is before the Spring Prediction Barrier which means we need to wait a few months until May [click here to understand why] before getting excited about that. Notice the wide spread among forecast member into the summer. 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.

The full list of weekly values can be found here.

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).

El Niño WATCH continues; eastern tropical Pacific waters warm

The tropical Pacific remains neutral with respect to the El Niño-Southern Oscillation (ENSO). However, there are signs that El Niño may develop in 2017, with the Bureau's ENSO Outlook status at El Niño WATCH. El Niño WATCH means there is around a 50% chance of El Niño developing in 2017, which is approximately twice the normal likelihood.

Sea surface temperatures in the tropical eastern Pacific Ocean have warmed, with the warmth progressively spreading westwards since the start of the year. Additionally, waters in the eastern Pacific subsurface have also warmed over the past few weeks. Waters near the South American coastline near Peru remain warmer than average, which has contributed towards heavy rains and flooding in parts of South America.

The pattern of very warm ocean conditions in the far eastern Pacific but neutral conditions overall is unusual. International climate models suggest the steady warming of the tropical Pacific Ocean is likely to continue in the coming months. Seven of eight models indicate that sea surface temperatures will exceed El Niño thresholds during the second half of 2017. However, some caution should be exercised as models have lower accuracy at this time of year, and there remains a significant spread in possible forecast outcomes.

El Niño is often, but not always, associated with below average winter–spring rainfall over eastern Australia and warmer than average winter–spring maximum temperatures over the southern half of Australia. For example, of the 27 El Niño events since 1900, 18 have resulted in widespread dry conditions for Australia.

JAMSTEC March 1, 2017 ENSO Forecast.

Based on the Nino 3.4 projection, JAMSTEC is saying the Cool Event did not meet the criteria to have been declared a La Nina as was done by NOAA: Nino 3.4 being colder than -0.5 and the duration of being under -0.5 was not sufficient  to qualify as a La Nina.

JAMSTEC is raising the possibility of an El Nino for the following winter. But it is too soon to make that prediction with a high degree of confidence.

The Discussion that goes with their Nino 3.4 forecast follows:  Notice the suggestion that we might be having a Pacific Climate Shift to PDO Positive.

Mar. 21, 2017 Prediction from 1st Mar., 2017

ENSO forecast:

The SINTEX-F predicts that a moderate-to-strong El Niño event may start in early summer this year and reach its peak in winter. If this happens, it may 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.

Indian Ocean forecast:

Occurrence of a positive Indian Ocean Dipole is also clearly predicted by the SINTEX-F seasonal prediction system; the ensemble mean prediction suggests its evolution in summer and its height in fall. We may 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 southern Canada and northern U. S., and northern Brazil will experience a colder-than-normal condition in the boreal spring. In the boreal summer, most parts of the globe will experience a hotter-than-normal condition. On the other hand, some parts of Europe, central Russia, and northern Australia will experience a cooler-than-normal condition.

As regards the seasonally averaged rainfall, a wetter-than-normal condition is predicted for western part of Brazil during the boreal spring, whereas most parts of southeastern China, Indonesia, eastern Brazil, southern Australia and Europe will experience a drier condition during the boreal spring. In the boreal summer, most parts of Indonesia, India, Australia, southeastern China, Mexico, and northern Brazil will experience a drier-than-normal condition, due to co-occurrence of the El Niño and the positive Indian Ocean Dipole.

Most parts of Japan will be in a warmer and drier-than-normal condition in the boreal spring. In boreal summer, we expect a wetter-than-normal and slightly hotter-than-normal condition due to development of the positive Indian Ocean Dipole and El Niño; El Niño influences may be canceled due to development of the positive Indian Ocean Dipole and vice versa.

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 9 April was +0.32 °C.

The influence of the IOD on Australian climate is weak during December to April. This is due to the monsoon trough shifting south over the tropical Indian Ocean and changing the overall wind circulation, which in turn prevents an IOD ocean temperature pattern from being able to form. The monsoon trough remains strong in the southern hemisphere at present.

Current outlooks suggest a neutral IOD for the end of autumn, with some models indicating a positive IOD may form later in winter.

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 are suggesting this as a possibility. But it is too soon to tell due to the Spring Predictability Barrier or SPB which is was explained at this link.

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

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.

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 April 10, 2017

The Jan/Feb/Mar preliminary has just come out as -0.2. 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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