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posted on 02 May 2017

May 1, 2017 Weather and Climate Report - NOAA Updates May Outlook

Written by Sig Silber

As regularly happens, on the last day of each month NOAA updates their previously issued "early" forecast for the following month which in this case is May. Usually the changes are small. This time the changes to the Precipitation Forecast are very large. The Temperature forecast has also been changed significantly and this is all just ten days from when the early forecast was made. The level of confidence in the 6 - 14 Day Forecast is fairly low especially the second week of that forecast. Combined, it suggests that we may be having a pattern shift which is both difficult to predict and especially difficult to pin down the timing. We will attempt to explain what is going on in the full report that follows.

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 are forecasting. We think it is implausible and our report 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.

Lowest Level of Drought in this Century.  Warmer generally means wetter but this is probably related to ocean cycles with the PDO becoming more positive and the AMO less positive. This has made El Nino or El Nino type events more likely than La Nina type events. The process is a bit counter-intuitive in that precipitation is enhanced by cold but evaporation is enhanced by warm so that is where the clouds form. We have had more clouds lately.  

El Nino versus Active Atlantic Hurricane Season.

The possibility that a strong Hurricane Season may be more likely than an El Nino seems to be ignored yet obvious to anyone looking at worldwide sea surface temperatures. Africa will be generating westerly tropical waves and the waters off West Africa are warm and warming but the Meteorological Agencies are obsessed with an El Nino that most likely will not happen or be borderline. 

For those who wish to track the musings of Dr. Phil Klotzbach from Colorado State University, here are two good links Colorado State University Tropical Meteorological Project and the most recent forecast click here. It is too soon to go into this in detail but  I am just trying to make the point that it is looking to me that this summer may be more active than some are predicting. Here is a very good NOAA Presentation on Atlantic Hurricanes and it provides maps of how the Hurricane Generation Areas change by month. Of course we are only in May. But next month is June and June is the first month of the Atlantic Hurricane Season.

NOAA Update of their Outlook for May

NOAA has, as usual, issued an update for the month following the last day of the prior month. This update was issued on April 30 and rather than have a Special Update that covers simply the next month, we combined that report with our Regular Weekly Report and we will discuss that first by comparing the Updated Outlook for May to the Early Outlook for May issued on April 20, 2017. 

Temperature

Prior Outlook Issued on April 20, 2017

May Early Temperature Outlook Issued on April 20, 2016

Updated Outlook Issued on April 30, 2017

Updated Temperature May 2017 Outlook Updated on April 20, 2017

The warm anomaly has shrunk and we now see an Upper Mississippi cool anomaly. That is a big change in ten days.

Precipitation

Prior Outlook Issued on April 20, 2017

May Precipitation Early Outlook Issued on April 20,  2017

Updated Precipitation Outlook Issued on April 30, 2017

May Precipitation Outlook Updated on April 20, 2017

Too many changes to discuss but I will in the section comparing the one - month to three-month maps. I also highlight some of the "reasoning" in the discussion which was released with the updated maps.

Below is the discussion issued with this update.

30-DAY OUTLOOK DISCUSSION FOR MAY 2017  

ENSO NEUTRAL CONDITIONS CONTINUED ACROSS THE PACIFIC OCEAN. THE SEA-SURFACE TEMPERATURES IN THE NINO 1+2, NINO4, AND NINO 3.4 REGIONS INCREASED. THE MJO REMAINED WEAK, THOUGH SOME MODELS DO INDICATE A STRENGTHENING SIGNAL ACROSS THE WESTERN HEMISPHERE, SO THERE COULD BE SOME RELATED IMPACTS DURING THE LATTER HALF OF MAY. UNCERTAINTY ABOUT THE DEVELOPMENT OF AN MJO, THEN THE ATTENDANT, LAGGED IMPACTS, RESULTS IN THE MJO BEING OF MINIMAL CONSEQUENCE IN THE UPDATED OUTLOOK. THE OUTLOOKS ARE CONSISTENT WITH SOME OF THE MJO LAGGED COMPOSITES CENTERED ON MAY.

THE UPDATED TEMPERATURE OUTLOOK REFLECTS GUIDANCE FOR EARLY IN THE MONTH WHERE TEMPERATURES ARE FORECAST TO BE BELOW AVERAGE ACROSS THE GREAT PLAINS, MIDWEST, AND MISSISSIPPI VALLEY. THAT PREDICTED COOLER AIR IS THEN LIKELY TO SLIDE SOUTH AND EAST, SO THE UPDATED OUTLOOK NOW REFLECTS THAT LIKELY COOLER FIRST HALF OF THE MONTH FROM THE SOUTHERN GREAT PLAINS TO THE OHIO VALLEY AND ACROSS TO THE MID-ATLANTIC. ACROSS THE SOUTHWEST AND GREAT BASIN, THE OUTLOOK IS RELATIVELY UNCHANGED, WITH THE HIGHEST ODDS OF ABOVE NORMAL TEMPERATURES SHIFTED NORTHWARD SLIGHTLY, GIVEN A PREDICTED COOLER PERIOD, MID-MONTH, OVER ARIZONA. UNCERTAINTY ACROSS THE NORTHERN GREAT PLAINS, NORTHERN ROCKIES, AND PACIFIC NORTHWEST, IS HIGH, SO NO TILT IN THE ODDS IS INDICATED FOR THOSE REGIONS. TEMPERATURES OVER MUCH OF ALASKA ARE PREDICTED TO BE ABOVE NORMAL, WITH A WARMER START TO THE MONTH. UNCERTAINTY IS HIGHEST OVER SOUTHEAST ALASKA AND THE ALASKA PANHANDLE.

THE PRECIPITATION OUTLOOK HAS BEEN REVISED CONSIDERABLY, GIVEN THE STRONG SIGNALS IN SHORT-TERM MODEL GUIDANCE AND OFFICIAL PRODUCTS. AN ACTIVE PERIOD IS FORECAST EARLY IN THE MONTH FROM THE GULF COAST TO THE NORTHEAST. A RELATIVELY SHORT WAVELENGTH AND A PREDICTED TROUGH OVER THE ROCKIES FOR THE MIDDLE OF THE MONTH SUPPORTS A BROAD SWATH OF FAVORED ABOVE MEDIAN PRECIPITATION FROM THE NORTHERN ROCKIES TO FOUR CORNERS REGION, WHERE MEDIAN PRECIPITATION AMOUNTS ARE LOW, SO EVEN A SHORT PERIOD OF WETNESS WOULD FAVOR ABOVE MEDIAN PRECIPITATION FOR THE ENTIRE MONTH. MODEL GUIDANCE AND OFFICIAL OUTLOOKS COVERING MOST OF MAY, FAVORS DRIER THAN MEDIAN CONDITIONS FOR THE PACIFIC NORTHWEST COAST, AND PORTIONS OF THE MIDDLE AND UPPER MISSISSIPPI VALLEY.

Sometimes it is useful to compare the present month outlook to the three-month outlook

May Plus  May  -  July  2017 Outlook

April and AMJ 2017  Updated on April 20, 2017

One can mentally subtract the May Outlook from the three-month Outlook and create the Outlook for the last two months in the three-month period namely June and July 2017. To  do that you need to take into account that:

For temperature there is much expanded coverage of the warm anomaly in the three-month period and the cool anomaly shown in May is gone in the three-month forecast. Thus if you assume these colors are assigned correctly, it is a simple algebra equation to solve June/July probability for a given location = (3XThree-Month Probability - May Probability)/2*. So you can derive the June/July forecast this way. You can do that calculation easily for where you live.
Re precipitation, there is the extension to the south of what in May is a North Central wet anomaly that does not reach to the Mexican Border. There are many other changes from May to the three-month forecast: The Northwest dry anomaly is gone, the Mid-Atlantic through to Northeast wet anomaly is gone, The Southern Plains wet anomaly is scaled back to just the immediate West Gulf of Mexico coastal areas, the Missouri and Iowa dry anomaly is now located in the Great Lakes. That is a lot of changes. So if you assume these colors are assigned correctly, it is a simple algebra equation to solve June/July probability for a given location = (3XThree-Month Probability - May Probability)/2*. So you can derive the June/July forecast this way. You can do that calculation easily for where you live.
One has to keep in mind that we are now subtracting a May Map issued on April 30 from a three-month map issued on April 20. So it is less reliable than the exercise we went through in the special Update Report. We are assuming that the three-month outlook issued on April 20 would not change if it was updated on April 30. The results in the box above might be an indication of how June and July will differ from the three-month outlook or it might alternatively indicate how the three-month outlook might be modified if issued today. So the discussion in the paragraph above this may be overruled by a conclusion that the three-month outlook is no longer correct and the updated May Outlook is a better predictor of the three-month outlook than the three-month maps issued on April 20.  From the discussion released by NOAA on April 30,  the changes mentioned would appear to be less than highly likely and I have a low level of confidence in both the May and three-month forecasts.

* The concept is that the probabilities of a deviation from climatology in the First Month and the combined Month Two and Three forecast that one derives must average out to the probabilities shown in the three-month maps.

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 1, 2017, as I am looking at the above graphic, we see the Southwest trough now having moved north and to the east presenting as a large Mid-West cyclone. You can really see the circulation.

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 action impacting the West Coast and also some distance away, the Great Lakes. It is now possibly in a position to pull up moisture from the Gulf of Mexico.

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 mostly moisture entering CONUS from the Pacific. Perhaps I was incorrect when I said the Pacific Storm from last weekend and the current Great Lakes weather were not connected. They seem to be connected in this graphic.

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 part in the Gulf of Alaska with central surface air pressure of 996 hPa. There is a second stronger part over by Kamchatka with central surface pressure of 980 hPa.  Remember this is a forecast for Day 3 not the current situation. The pattern has been changing rapidly with these Lows getting stronger and weaker and changing their location dramatically every time this graphic is updated. 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 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? But there is also an inland High Pressure System with central surface air pressure of 1014 hPa. There is thus now for Day 3 not much of a block on Pacific Storms entering CONUS south of Canada. And yet NOAA is not predicting a continuation of the recent pattern. It looks like it is possible for storms to enter CONUS from south of the High off the West Coast.
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. It might be suggesting that there will be impacts re the Southeast. Notice the kink (tight curve) in the Jet Stream that may be separating from the main branch and perhaps passing over Southern California as a cut-off low. That may be a factor in a week. 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 a lot of moisture in the Plains States and East Coast. The graphic shows the cumulative precipitation over a seven-day period. Notice that the trough that recently impacted the Southwest came and went with little precipitation impact. That is why the Southwest is called semi-arid. Even when storms come through, they often bring more wind than precipitation.

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 the prior Western Trough projected to be approaching New England and moving out to sea. We now have a new West Coast Trough with a possible cut-off Low and a huge Central CONUS Ridge. The forecast re that cut-off low may take a few more days to become reliable. It could be a lot wetter than the storm that just recently impact the Great Basin and then points east. It is unusual to have that kind of cut-off Low in that location this time of the year.
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 1, 2017 was 3 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 1, 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 Forecasts

Interpreted on May 1, 2017

May 7 to May 15 May 13 to May 26

Days 6 - 10: CONUS is cool in the Southwest and in the East and warm in the  Center except for the southern tip of Texas which is cool. Alaska is warm.

The Southwest remains warm but not with the same geographical extent, and again the Southeast is warm and New England is warm. The expanded North Central is cool and really extending far south into Texas. 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 feasible. Again the forecast for the Southeast seem to be the least likely to be a zonal progression.

Week 2:  As the period evolves, the CONUS pattern shifts dramatically  to the east and north. This brings cooler temperatures to southern Mainland Alaska. It also brings warmer temperatures to southern Texas and Florida.
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 1, 2017 was 3 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 1, 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 Forecasts

Interpreted on May 1, 2017

May 7 to May 15  May 13 to May 26, 2017
Days 6 -10 The West is  wet except for a small dry anomaly in the Northwest. The Eastern half of CONUS is dry except for New England which will be wet. Alaska is dry in the north and wet in the south and the Panhandle.

For CONUS, the Northwest is again dry. The dry anomaly which last week was shown impacting the expanded Great Lakes Area is now shifted to the east a  bit. Colorado, New Mexico and Texas are wet again but the wet anomaly now extends all the way to Canada but may also be a bit shifted to the east. For Alaska only the extreme south and Panhandle are dry. 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 somewhat complicated.

Week 2: For CONUS, the Wet anomaly shifts slightly to the east and thus has a bit more geographical extent. The East dry anomaly shrinks quite a bit and the higher probabilities shift from south to north.The Northwest dry anomaly expands to the south. For Alaska the wet anomaly engulfs almost all of Alaska.

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 1, 2017.

6-10 DAY OUTLOOK FOR MAY 07 - 11 2017

TODAY'S DYNAMICAL MODEL SOLUTIONS FOR THE 6-10 DAY PERIOD ARE IN GOOD AGREEMENT ON THE EXPECTED 500-HPA CIRCULATION PATTERN OVER MOST OF NORTH AMERICA. AMPLIFIED TROUGHS ARE PREDICTED OVER THE EASTERN AND SOUTHWESTERN CONUS AND THE BERING SEA/ALEUTIANS, WHILE RIDGES ARE ANTICIPATED OVER THE WEST-CENTRAL ATLANTIC, THE WEST-CENTRAL CONUS, AND WESTERN CANADA AND ALASKA. ENSEMBLE SPREAD IS MODERATE OVER THE MAJORITY OF THE FORECAST DOMAIN. TODAY'S OFFICIAL 500-HPA MANUAL HEIGHT BLEND INDICATES NEAR TO ABOVE NORMAL HEIGHTS OVER ALASKA AND THE NORTHWESTERN AND CENTRAL CONUS, WHILE NEAR TO BELOW NORMAL HEIGHTS ARE EXPECTED OVER THE EASTERN AND THE SOUTHWESTERN CONUS.THROUGH OVER THE EASTERN CONUS IS QUIT DEEP FOR THE TIME OF THE YEAR. 

ABOVE NORMAL HEIGHTS ENHANCE PROBABILITIES FOR NEAR TO ABOVE NORMAL TEMPERATURES FOR MOST OF THE NORTHWESTERN AND THE CENTRAL CONUS, WHILE BELOW NORMAL HEIGHTS FAVOR NEAR TO BELOW NORMAL TEMPERATURES FOR THE EASTERN AND SOUTHWESTERN CONUS. ABOVE NORMAL HEIGHTS AND ABOVE NORMAL SEA SURFACE TEMPERATURES ENHANCE PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR ALASKA.

THE TROUGH FORECAST OVER THE EASTERN CONUS FAVORS ABOVE MEDIAN PRECIPITATION FOR PART OF NORTHEAST. ANOMALOUS NORTH/NORTHWESTERLY FLOW TILTS THE ODDS TO BELOW MEDIAN PRECIPITATION FOR THE CENTRAL AND EASTERN CONUS. THE TROUGH PREDICTED OVER THE SOUTHWESTERN CONUS ENHANCES PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE WESTERN CONUS, EXCEPT FOR THE NORTHWEST COAST, WHERE ABOVE NORMAL HEIGHTS FAVOR BELOW MEDIAN PRECIPITATION. BELOW NORMAL HEIGHTS AND THE TROUGH FORECAST OVER THE BERING SEA ENHANCE PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR THE ALASKA PANHANDLE, SOUTH COASTAL ALASKA AND THE ALEUTIANS, WHILE RIDGING FAVORS BELOW MEDIAN PRECIPITATION FOR PARTS OF NORTHWESTERN ALASKA.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO  GOOD AGREEMENT ON A MODERATELY AMPLIFIED PATTERN FOR MUCH OF THE FORECAST DOMAIN AND FAIRLY GOOD AGREEMENT AMONG THE FORECAST TOOLS, OFFSET BY MODERATE SPREAD AMONG THE ENSEMBLE MEMBERS AND THE EXPECTATION OF A PROGRESSIVE FLOW  PATTERN.

8-14 DAY OUTLOOK FOR MAY 09 - 15 2017 

COMPARED TO THE 6-10 DAY PERIOD, THE OVERALL CIRCULATION PATTERN IS EXPECTED TO BE PROGRESSIVE DURING WEEK-2. TROUGHS ARE FORECAST OVER THE NORTHEASTERN AND WESTERN CONUS AND THE ALEUTIANS/ALASKA PENINSULA, WHILE RIDGES ARE ANTICIPATED OVER THE CENTRAL CONUS AND ALASKA. THE ENSEMBLE SPAGHETTI CHARTS INDICATE RELATIVELY HIGH SPREAD ACROSS MOST OF THE FORECAST DOMAIN WITH LARGE  DIFFERENCES NOTED IN BOTH AMPLITUDE AND PHASE OF INDIVIDUAL SHORTWAVE FEATURES.  TODAY'S WEEK-2 BLENDED 500-HPA HEIGHT CHART INDICATES A RELATIVELY WEAK HEIGHT ANOMALY PATTERN, DUE TO THE HIGH SPREAD AMONG ENSEMBLE MEMBERS. NEAR TO BELOW NORMAL HEIGHTS ARE PREDICTED OVER THE EASTERN AND SOUTHERN CONUS, WHILE NEAR TO ABOVE NORMAL HEIGHTS ARE ANTICIPATED OVER THE MUCH OF THE NORTHWESTERN AND NORTH-CENTRAL CONUS AND ALASKA.

BELOW NORMAL HEIGHTS ENHANCE PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE EASTERN CONUS, AND THE CENTRAL PLAINS, AND THE SOUTHWESTERN CONUS.  NEAR TO ABOVE NORMAL HEIGHTS FAVOR NEAR TO ABOVE NORMAL TEMPERATURES FOR MOST OF THE NORTHWESTERN CONUS AND NORTHERN PLAINS, SOUTHERN TEXAS AND FLORIDA. ANOMALOUS SOUTH/SOUTHEASTERLY FLOW ENHANCES PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR MOST OF ALASKA, EXCEPT FOR MUCH OF SOUTHERN ALASKA.

ANOMALOUS NORTH/NORTHEASTERLY FLOW FAVORS NEAR TO BELOW MEDIAN PRECIPITATION FOR THE EASTERN HALF OF THE CONUS, EXCEPT FOR THE NORTHEAST. THE TROUGH OVER THE WESTERN U.S. TILTS THE ODDS TO ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE INTERIOR WESTERN CONUS AND THE SOUTHERN PLAINS. ABOVE NORMAL HEIGHTS FAVOR BELOW MEDIAN PRECIPITATION FOR NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST COAST. THE TROUGH NEAR THE ALEUTIANS FAVORS ABOVE MEDIAN PRECIPITATION FOR ALASKA.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE  TO FAIRLY GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS OFFSET BY LARGE  SPREAD AMONG INDIVIDUAL ENSEMBLE MEMBERS, AND RELATIVELY WEAK HEIGHT ANOMALIES. 

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.

Day

ENSO

Phase

PDO AMO

Other Comments

Apr 24, 1957 El Nino -(t) -  
Apr 10, 1964 La Nina - N Immediately after an El Nino Modoki Type II
Apr 26, 1966 El Nino - N  
Apr 15, 1969 El Nino - N Modoki Type II
Apr 16, 1969 El Nino - N Modoki Type II
Apr 18, 1976 La Nina - - Tail End
Apr 21, 2004 Neutral + +  
Apr 22, 2004 Neutral + +  
Apr 24, 2007 Neutral N +  

(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 10 to April 26 which is 16 days which is a very tight 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 April 18. These analogs are centered on 3 days and 4 days ago (April 27 or April 28). So the analogs could be considered to be very out of in sync with the calendar meaning that we will be getting weather that we would normally have 10 days earlier in the year. The question is what if anything does this mean. For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are three ENSO Neutral Analogs, four El Nino Analogs, and two La Nina analogs. Looks like the analogs are signaling ENSO Neutral with a El Nino bias. The phases of the ocean cycles of the analogs are inconclusive and confusing because so many are associated with PDO-. I think the explanation is partly the time of the year which is typically a time that phases of the ENSO cycle change. It may also be related to the approach of a Rossby Wave during the forecast period.

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 22, 2017

April 22,  2017  30 Day temperature and precipitation departures.

Looks like the North Central drought has moderated. The warm temperature anomalies have moderated also. Remember this is a 30 day average and seven more recent days have been added and seven more distant days are removed.

And the 30 Days ending April 29, 2017

April 29, 2017 30 Day Temperature and Precipitation Departures

The Precipitation map is just a bit muted. The Temperature anomalies are much changed. From west to east the warm anomalies are being reduced. Remember this is a 30 average with seven recent days added and seven distant days 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 at the beginning 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. The anomalies are more muted than recently.

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 (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 continues to remains wet. Also notice the strong Low in the Northern Pacific.

Temperature

BOM Current Temperature Wedensday

As for many weeks, Northern Africa, The Arabian Peninsula, and India are projected to be very warm. The west coast of South America looks cool.

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
Caspian Sea cool. Black Sea and Mediterranean neutral. Cool except west of Japan and east of Siberia Warm in places. Warm Cool in spots.
The Tropical Pacific

Neutral

Africa West of Australia South and East of Australia West of South America East of South America
Warm off Northwest Africa, West Africa and South Africa. Cool east of Africa Neutral Slightly warm Southeast Neutral Warm south of 30S near the coast and less than last week.

 

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.

May 1, 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
Cooling Slight Cooling around  Japan and much southeast of Kamchatka. Otherwise warming Warming off of Alaska Panhandle and off of Baja Warming but cooling in Gulf of Mexico Warming off of NW Africa and Spain. Cooling further north
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 off Northwest coast and West Coast.  Warming south.and slight warming east Cooling in the north. Warming Midway between Australia and Madagascar Cooling east. But warming southeast of New Zealand Cooling near Equator but warming south. Very significant cooling midway between South America and Australia Cooling off of Argentina and south of South America

 

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 May 1 for what is shown as Week Two, the period May  3, 2017 to May 9, 2017, we see dry conditions* for Indochina and small wet areas* for Somalia and Central America.
* 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 top graphic the big difference between temperatures 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

165E

0

0

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

165E

LAND

110

50

0C or cooler Anomaly (coolish neutral)

LAND

LAND

0

0

* A warm anomaly exceeding +0.5C is showing South of the Equator in today's TAO/TRITON Five-Day Mean Graphic. 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 1, in the afternoon working from the April 30 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 +0.4 +0.4
B. 160W to 150W +0.4 +0.4
C. 150W to 140W +0.5 +0.4
D. 140W to 130W +1.0 +0.6
E. 130W to 120W +1.3 +0.7
Total +3.6 +2.5
Total divided by five i.e. the Daily Nino 3.4 Index (+3.6)/5 = +0.7 (+2.5)/5 = +0.5

 

My estimate of the daily Nino 3.4 SST anomaly tonight is +0.5 which is a marginal El Nino value. NOAA has again reported the weekly Nino 3.4 to be a marginal El Nino value at +0.5 which is the same as my estimate. The disparity between surface temperatures north of the Equator and south of the Equator is striking and from a measurement perspective slight changes in wind and currents can move cooler or warmer into the Nino 3.4 Measurement Area and impact the numbers reported without really having a big impact on the actual situation. 
Nino 4.0 is reported the same as last week at +0.3. Nino 3 is also the same as last week at +0.6. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported slightly lower at +1.0.  I believe it was up there close to 3 at one time so this index has been fluctuation quite a bit.
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 1, 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 1, 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 160W east and browns from 110W east but now only from 90W east as the waters off of Ecuador and Peru have cooled. The reds are no longer showing at the bottom of the chart. 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 1, 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.

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 1, 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 155W to 135W with a smaller one and now a larger one further east. . 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. But the surface is just a bit warmer. But even that seems to be fading.

Now for a more detailed look. Notice by the date of the graphic (dated April 28, 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 and -0.5C water no longer shows anywhere. On the other hand, warm water continues to extend from the Coast of Ecuador to 90W and slightly warm water all the way to 150W but in many places very shallow and in some cases cool water just below the warmer water. Subsurface Temperature Anomalies: The cool water is still there. Notice the warm water at depth but there is a big gap east of 170W. 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.

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

It shows the thermocline between warm and cool water. The 28C Isotherm is now located at the 170W which is a shift to the east. 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. So there has been movement to the east since last week. 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 but on the fringe of minimal El Nino levels. The 25C isotherm now extends all to the way to Ecuador and in places is at the surface. The 20C Isotherm is 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. But this process seems to be happening very slowly at this point in time.
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 May 1 was reported as -6.47 which is ENSO Neutral but getting close to an El Nino value. The 90 Day Average was reported at -1.63 which is ENSO Neutral. 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.

 

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 April (April 13) 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.

April 20, 2017 CPC/IRI Update two graphics side by side.

First we look at graphic on the left which is the IRI/CPC what I call the "Tea Leaves Report" issued on April 13, 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. Then we look on the right at the most recent (April 20) Model Based report. Notice the new report has much higher and sooner probabilities for El Nino than the prior report.

Here click to read is the discussion that was issued with the April 20 Report.e human judgment in combination with the model guidance.

When the Tea Leaves version of the report is issued on May 11, we anticipate a very different report that shows the changes of an El Nino this Winter to be close to Neutral with real question being whether it will qualify as an El Nino or a near El Nino. 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 and shooting higher fairly rapidly this month. Looking ahead to next summer you see El Nino readings being the mean of the forecast ensemble but this forecast is still before the Spring Prediction Barrier which means we need to wait 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 - click to read.

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). Also the seasons in the Southern Hemisphere are the reverse of those in the Northern Hemisphere.

ENSO neutral, but tropical Pacific waters continue to warm

The El Niño–Southern Oscillation (ENSO) remains neutral. However the Bureau's ENSO Outlook is currently at El Niño WATCH, meaning there is around a 50% chance—twice the normal likelihood—of El Niño developing in 2017.

Tropical Pacific sea surface temperatures (SSTs) have warmed since the start of the year. SSTs in the central tropical Pacific are now 0.5 °C warmer than average, still below the +0.8 °C threshold for El Niño levels. Atmospheric indicators of ENSO remain firmly neutral, although the Southern Oscillation Index (SOI) has returned to negative values over the past fortnight.

International climate models suggest the tropical Pacific Ocean is likely to continue warming in the coming months, though in recent weeks some models have reduced the expected extent of warming. Five of eight models indicate that sea surface temperatures will exceed El Niño thresholds during the second half of 2017; a reduction of two models since the last Wrap-Up release. It should be noted that models have lower accuracy at this time of year.

El Niño is often, but not always, associated with below average winter–spring rainfall over eastern Australia. Of the 27 El Niño events since 1900, 18 resulted in widespread dry conditions for parts of Australia.

The Indian Ocean Dipole (IOD) is currently neutral.. Four out of six climate models suggest a positive IOD is likely during winter. When a positive IOD coincides with El Niño, the typical El Niño dry signal expands, and generally stretches further west over eastern and central Australia.

Here is the JAMSTEC forecast of the Nino 3.4 values which are the most looked at index used to forecast El Nino. That report was issued just after April 1. We have not yet receive the May 1 version which usually takes about a week after the start of the month for them to issue.

JAMSTEC April 1, 2017 ENSO Forecast.

This is the Discussion that goes with their April 1 Nino 3.4 forecast: It will be mid may before it is updated.

Apr. 18, 2017

Prediction from 1st Apr., 2017

ENSO forecast:

The SINTEX-F predicts that a moderate-to-strong El Niño event may start in late spring this year and reach its peak in winter. This probability is enhanced 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.

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 from late spring and its peak in fall. In accord to the positive IOD evolution, sea level anomalies are expected to be negative (positive) in the eastern (western) tropical Indian Ocean. We may observe co-occurrence of a positive Indian Ocean Dipole and an El Niño 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 southeastern 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 southern and eastern Russia and Somalia 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 Southeast Asia, Philippines, the Far East, and West Africa during the boreal summer, whereas most parts of Indonesia, Australia, India, eastern China, and northern Brazil will experience a drier condition during the boreal summer. In the boreal fall, most parts of Indonesia, Philippines, northern India, Australia, Mexico, southern Brazil and Europe will experience a drier-than-normal condition. 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-than normal in summer. In particular, we expect more rain in the western Japan in the Baiu season. In contrast, we expect a drier condition in fall. El Niño influences may be canceled regionally owing to development of the positive Indian Ocean Dipole and vice versa.

On Saturday April 22 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 April 20

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

Indian Ocean Dipole outlooks  [Editor's Note: Remember the Seasons are reversed in the Southern Hemisphere as compared to the Northern Hemisphere]

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 23 April was +0.2 °C

The northern Australian wet season is nearing its end. This means the IOD may start to influence the Australian climate. When the monsoon trough and associated wind patterns are located in the southern hemisphere, an IOD circulation is unable to develop. Therefore, the IOD has little influence on Australian climate from December to April.

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.

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 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

Utter Confusion about the Impact of Arctic Amplification (it is getting warmer there faster than lower latitudes)

NYT Readers Flip Out Over a Suggestion that People be Objective

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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