posted on 02 June 2015
Written by Sig Silber
The NOAA June update contained some tweaking of the outlook but no major changes. We are at a time when, to a large extent, the next four months are pretty much high-probability events and fairly easy to forecast as being relatively wetter and warmer than usual for this time of the year in the U.S.. The real question has to do with the duration and to some extent the intensity of the current Warm Event.
This week's report also includes a new paper on the Atlantic Multidecadal Oscillation (AMO) which I think says nothing new about weather impacts but presumably adds confidence in the understanding of the dynamics of the AMO. It does however present a fairly shocking forecast re Atlantic Coast sea-level rises. Six inches made a difference re Hurricane Sandy so a suggestion that the rate of ocean rise may now be higher for some decades would change my mind about where I wanted to locate a house at the shore. Full disclosure: I grew up in Atlantic City so I have a feel for high tides.
This is the Regular Edition of my weekly Weather and Climate Update Report. Additional information can be found here on Page II of the Global Economic Intersection Weather and Climate Report.
NOAA Issues Seasonal Update
First let's take a look at the prior outlook and the revised outlook for temperature and precipitation.
Here is the "Early" Temperature Outlook for June which was issued on May 21.
And here is the updated Temperature Outlook for June issued yesterday May 31, 2015.
The big difference is a warmer northern tier and a slight adjustment to the outlook for Alaska. It is remarkably similar.
Here is the "Early" Precipitation probabilities for June issued on May 21, 2015.
And here is the update issued yesterday May 31, 2015
Alaska is no longer EC but is predicted. The Northwest coast 'drier than' climatology area is shown and there is some 'drier than' climatology projected for the Great Lakes area and projecting down from the Great Lakes it is now EC rather than wetter than climatology. The Northeast is wetter So this is more of a change than the temperature outlook for June but still not a dramatic change.
And here is the NOAA discussion.
For ease of reference, I have created an update of the graphic that NOAA shows with the current month and three-month outlooks. They do not auto-update that graphic to include the revised current month outlook so I did it for them.
It is useful in thinking about whether or not the end of month update of the following month has implications for the subsequent two months which are issued on the third Thursday of the month. When issued on March 21, June and the three-month outlook were almost identical. Now that June has been tweaked does that tell us anything about July and August?
I will now shift timeframes dramatically.
Current (Now to 5 Days) Weather Situation:
For daily forecasts it is better to consult your local weather service or the weather service where you are traveling as these will be more specific. But I do have daily forecasts on Page II of the Report so you can always look at those as they auto-update. What I present here is information that normally is not made available via local weather forecasts and which can help you understand what some of the major drivers are for the local forecast.
First here is a national 12 hour to 60 hour forecast of weather fronts shown as an animation. Beyond 60 hours, the maps are available in Part II of the Global Economic Intersection Weather and Climate Report.
The explanation for the coding used in these maps i.e. the full legend can be found here.
There has been talk of a Pacific Hurricane and indeed there is one. But so far it does not appear to be much of a factor re CONUS.
There is always the possibility that the outer circulation can enter the circulation of a High or Low over CONUS and provide moisture to that feature. This is a useful diagram attributable to Kelvinsong.
So we can monitor the below to see if this cyclone is providing water vapor to weather patterns impacting CONUS. So far it has not but you can see at the bottom the circulation of Andres approaching us and most likely will merge with weather patterns over CONUS. And there is another storm yet unnamed right behind Andres. Oops, it now has a name: Blanca. More are likely to follow. Since these storms are not likely to come onshore, the wind intensity is less important than the extent and location of the cloud pattern.
You can see that the U.S. is overall pretty well supplied with water vapor right now. That is partially due to the warm water off the West Coast. But the Gulf of Mexico has also been a source of moisture. And the Warm Event along the Equator also enhances the level of atmospheric moisture.
Not all moisture converts to precipitation. Based on my Weather Modification research, for the Rocky Mountain States the generally accepted numbers are that about 20% of moisture forms clouds and about 30% of the water in clouds falls as precipitation. So (0.2)X(0.3) is 0.06 or about 6% of the moisture passing over these states ends up as precipitation. I have no idea what the numbers are for states that do not have mountains. One thing is for sure, there is a lot of moisture in the atmosphere and that is not going to change due to Global Warming or at least it is not going to decline.
Most scientists think of this in terms of the transfer between oceans and land. And the way to look at it is by considering E (evaporation) and P (precipitation). Like in economics where Savings must always equal Investment when looked at on a global basis, with water E must equal P except for increases in the amount of water stored in the atmosphere which can hold more water if warmer. In the short term we can assume that E = P. So one can then look at the oceans where E is always greater than P because clouds are driven by winds on shore. Thus we conclude that this shortfall between P and E over oceans implies that P will be greater than E over land to balance the equation. You will find this in all climate models. If there were no winds, then E would equal P over oceans and E would equal P over land. Warming might cause E to increase but P would follow. The atmosphere as it warms can hold more moisture but other than that, which is important, there is no way that more evaporation will not result in more precipitation.
Now, where the precipitation falls is another and more complicated question. The simplistic notion is that those who get, get more but that is only a starting point for investigation. One can look at water availability a lot like a trade equation with imports and exports of moisture. Since Warming will not occur evenly, the export of moisture will also not occur evenly. But you can not export that which you did not import unless you have glaciers or lakes. The surface of the earth does not store much water compared to the total amount of activity. So to a large extent, Global Warming models are attempting to address the question of changing moisture import and export patterns. It would be very helpful if those involved with water planning understood this very simple principle.
Getting back to our near-term and seasonal forecasts, activity in terms of the west to east pattern has slowed down for the warm season so we will have less precipitation coming onshore and more recirculating over land. That is why hurricanes have always been welcome even if damaging because the moisture is very useful during times of the year when there is less regular inflow of moisture off the oceans. The other exception to this pattern of less moisture entering CONUS from oceans is the North American Monsoon where Pacific and Gulf of Mexico moisture is sucked into the circulation as the wind shifts from the west to from the southwest and southeast. That is not supposed to happen until mid July but it has been happening all winter to some degree. And we have that Warm Event with higher than usual convection near the Equator off of Ecuador which I suspect is causing these storms to form in the Eastern Pacific.
Local forecasts are beginning to mention the "Subtropical Ridge" This is important re the development of the Southwest Monsoon but also it impacts the Southeast. This is something we need to pay attention to.
Sometimes it is useful to take a look at the location of the Jet Stream or Jet Streams. This and the following graphic update every six hours. The continuation of the split jet stream may be related to the Warm Event. But I do not see a lot of activity that is very far south.
And sometimes the forecast is revealing. Below is the forecast out five days. The Jet Stream especially the southern branch may be starting to be less intense and you can read the wind speed expressed in knots per hour off of this graphic.
To see it in animation, click here.
This longer animation shows how the jet stream is crossing the Pacific. This time of year, it usually is having less of an impact.
And below is another view which highlights the surface highs and the lows re air pressure on Day 3. The Aleutian Low is still surprisingly active and probably is the most obvious indication of this Warm Event and has kept Alaska warmer and wetter than usual all winter. It has been moving around quite a bit, splitting into two lows and in other ways complicating forecasting. The Aleutian Low still impacts Alaska but depending on its location has alternatively more or less of an impact on CONUS. The RRR which normally is not active in an El Nino year but is active in an El Nino Modoki Type II year is still in the picture but is a shadow of its former self (i.e. no tightly wound isobars). The RRR still has the ability to keep the Northwest toasty warm and dry. Also considering that in the northern hemisphere, high-pressure systems are clockwise circulations, you can see where Hurricane Andres is going and why it will quickly decline to tropical storm strength. It shows up just off to the left in this graphic as I am writing my report but will be out of the picture by the time you look at.
And here is Day 6. Where is Andres? But notice the next in what is most likely going to be a sequence of low pressure systems moving up the coast of Mexico. . .
Outlook Days 6 - 14 (but only showing the 8 - 14 Day Maps)
And here is the 8 - 14 Day Temperature Outlook issued today June 1, 2015. It covers the week following the coming week.
I did not plan to have to do this but here is a repeat graphic of the monthly outlook issued YESTERDAY and shown earlier in this report.
Today's Outlook is just nine days of the month and the map of the 8 to 14 day Outlook only shows seven days but it does seem substantially different from the month outlook issued just yesterday.
Here is the 8 - 14 Day Precipitation Outlook issued today June 1, 2015.
And the full month outlook issued YESTERDAY.
And again remember that this map shows only seven days and the full 6 - 14 Day Outlook only covers nine days. There are 30 days in June. Notice the drier than climatology area is shown over the Dakotas and adjacent states rather than over the Great Lakes. There appears to be a possible change in thinking about New Mexico and Texas. Some of this was suggested by the above full-month outlook map and in the discussion that was issued with that map. The discussion indicates that the probabilities of exceeding climatology levels of precipitation were lowered but not all the way to EC. Now we see lower than climatology precipitation for much of Texas in the 6 - 10 day Outlook Map available in Part II of my Report and EC for days 8 -14 for parts of Texas and New Mexico so that may be a change in thinking.
Here are excerpts from the NOAA release today June 1, 2015.
Analogs to Current Conditions
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 analyzing this second set of information. This first set applies to the 5 and 7 day observed pattern prior to today. The second set which I am not using relates to the forecast outlook 6 - 10 days out to similar patterns that have occurred in the past during the dates covered by the 6 - 10 Day Outlook. That may also be useful information but they put this set of analogs in the discussion with the other set available by a link so I am assuming that this set of analogs is the most meaningful.
The most striking aspect of these analogs is the 1957 analog which was a fairly strong El Nino. That decade had some fairly significant changes from year to year. The 1957 analog has shown up for at least three days in a row and if it continues to show up I will discuss that period of time in more detail next week. There is no clear-cut pattern of the low-frequency ocean cycles perhaps because the medium-frequency ENSO Cycle currently dominates. There is still a lot of variability in the analogs which I think complicates the forecasting to some extent. Also we should remember that NOAA uses a single set of analogs not analogs by region of the forecast area.
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.
Progress of the Warm Event
Here are the low-level wind anomalies
It is not as compact as the graphic provided by the weekly ENSO Report (more white space) but this version auto-updates so you will always have the latest version of this Hovmoeller. As you can see the wind gust of a few weeks ago is over and even the secondary anomaly at 140W appears to be over. The Eastern Pacific has returned to normal.
Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day running average and the third is the 90 day average.
This past week, the SOI has been very negative for the development of or confirmation of the existence of an El Nino. Usually -8 is considered El Nino Conditions. Sometimes -6 is used for local forecasting in Australia. The 30 average, which is the most widely used measure, on June 1 was reported as being -13.18 which is definitely in El Nino territory but much less so than the -16.95 reported last Monday. The 90 day average also continues in El Nino territory. It has become less El Nino-ish but being a 90 day average it moves more slowly. This continues to be a very perplexing Warm Event.
Let us now take a look at the progress of the Kevin wave which is the key to the situation. This animation shows the progress of the current Kelvin Wave. Sometimes this animation is a bit cranky so you may need to hit the refresh button on your computer or go here to get a fresh copy.
It is clear that this Kelvin Wave is progressing and will exit stage right fairly soon.
Here is a static version that is easier to read. You can see both the magnitude of the anomalies and their size. The six degree warm anomaly was quite impressive but hardly showing now and compared to the size of the Pacific Ocean it is just a blip. To the fishermen in Peru and Ecuador it is anything but a blip reminding us to keep things in perspective which varies depending on where you are at any given point in time. You can now see where 2C (anomaly) water is impacting the area where the ONI is measured i.e. 170W to120W. This will be apparent when we discuss the TAO/TRITON graphic and my crude estimation of the ONI value that is the situation right now. You can I think see why computer models come to different conclusions on the peak values of the ONI (usually three-month averages are what are used to assess the intensity of a warm or cool event). Some models show predicted monthly values which are very useful but which can be misinterpreted. It takes some time for warm water at the surface to trigger convection and impact the Walker Circulation. This is very important since the reason for monitoring the ENSO Cycle is to gain an understanding of how it might impact weather over land areas. If there is little or no impact over land areas, it is almost as if the ENSO event did not occur. Our tools for predicting impacts lag our tools for measuring certain aspects of the ENSO Cycle.
The bottom half of the graphic is not too useful as it simply shows the thermocline between warm and cool water which pretty much looks like this as shown here except now the cooler water is now making it to the surface to the east along the coast of Equator. That is why this warm even is NO LONGER A PURE MODOKI. To me it looks like the tail-end of a traditional/canonical El Nino. How it will be recorded in history remains to be seen as it is not usual for a Modoki to transform itself into a Canonical El Nino and it is not usual for any of this to occur at this time of the year. So this is a very unusual situation. Also NOAA took liberties with their own criteria when they declared this warm event an El Nino so for many reasons the description of this warm event may vary around the world. This is a negative for future research efforts. The upper graphic shows the anomalies and although NOAA has not yet noted that there is a potential upwelling wave in the Western Pacific, it shows up clearly on this graphic. Actually they have mention this in one of their graphics this week but not on their Kelvin Wave graphic. What they have done is pencilled in an offshoot new downwelling Kelvin Wave. That could be the catalyst for extending the life of this Warm Event but I think they might be premature in showing in on their graphic. By next week perhaps we will have a better idea of what is happening.
The key to the equation here is will there be a follow-up downwelling wave and so far that is not showing up. That is why I am skeptical about all of the ENSO model projections that show this El Nino continuing beyond July of this year. It is clear that the impacts on Ecuador and Peru will last two months longer than anywhere else. You can also see that those impacts are extreme with water that is 5C and 6C warmer than usual crashing into the coast of Ecuador and Peru with the Galapagos Islands clearly involved. Not that I have attempted to research it, but I have not noticed anything being written about this which I assume is a fairly negatively impactful in that area. In addition to the impact on fisheries, there could be some heavy rains and warm water facilitates the development of cyclones.
Here is another animation that covers a larger area but with the same information. Do not be concerned about the gray streaks. The two in the center are on the left Australia and on the right Central America and the the extreme left and right are Africa with 30E splitting Africa. Not sure exactly why they display this the way they do but I assume it is because the wish to focus on the Equatorial Pacific since that is what counts for the ENSO Cycle.
It really shows that when the Kevin wave crashes into Ecuador, the warm water in this case has gone quite deep and if I had a 3D graphic it would show that it heads north also. But you can see the colder water to the west of this Kevin Wave which is what make me think the computer models are simply WRONG. There appears to be no Force Manoeuvre for this Kelvin Wave as was said by the British to the French after the Maginot Line failed.
I like this animation a lot. You can see with regards to 170W to 12W where NOAA measures the ONI how first the water near the surface was under 1C in terms of the anomaly. Then you can see water warmer than 1C rising to the surface. You can see the 2C+ zone of subsurface water which if it rises into the Nino 3.4 zone would signify a very powerful El Nino. Does it look like that will happen? Not to me although I could see it in the eastern end of the 170W to 120W measurement zone. On the other hand, it looks like the 0.5C to 1C anomaly will reach 170W at some point which will then be followed by a decline in the measured ONI. It has certainly moved more slowly than I expected. But it has no choice but to move in that direction. So when that happens, the ONI readings will begin to decline.
I simply do not understand the thinking that this El Nino can extend into late 2015 without another Kelvin Wave developing. That of course could happen but there is no sign of it yet. I am perplexed by the tendency of the computer models to extend this Warm Event. I may well be missing something. We shall see. For those who never get tired of looking at graphics, this is a useful source of information
Here are the surface anomalies
It is up to date. It does auto-update including updating the date which surprised me this week. I publish my article on a Monday evening but generally I take a look at it each day to make sure it is "behaving" and in so doing I learn about how my graphics are working since I do not create them but borrow them from government reporting agencies.
This Seasonal Anomaly graphic also autoupdates but I think it does so on a weekly basis which fortunately was this past Saturday so it is quite up to date. You can see the PDO+ Pattern and the El Nino combination of a Modoki Type II and a Canonical/Traditional El Nino and the warm Gulf of Mexico and the Negative IOD in the Indian Ocean. You also see cooler water off of West Africa that suggests a weak Atlantic Hurricane Season.
And you can see the change especially along the Equator in the Pacific. Notice that a daily picture shows more detail than when you have three months of daily pictures averaged.
Here it is as an animation showing the recent evolution of the sea surface temperature anomalies. If it does not start up by itself, please hit this start button.
For my own amusement, I thought I would recalculate the ONI again as I have been doing recently. The little tick marks on the chart can be used instead of a ruler. When I print out this graphic, one tick is about one centimeter. So you can use a ruler or just estimate the number (including fractions) of tick marks.
You can see that there is more warmer water west of 120W which raises the ONI. You can also see that the western extent of the warm water now extends west to the Date Line which is a surprise to me. It is difficult to pin down the exact rate that this warm water will cease to signal an El Nino but it remains IMO fairly soon as in two to three months.
So as of Monday June 1 in the afternoon working from the May 31 TAO/TRITON report, this is what I calculated.
My estimate of the Nino 3.4 ONI is now 1.75 which is quite high. NOAA is reporting 1.3 which may be a bit low. My method has the limitation that I am doing the calculation based on measurements right on the Equator whereas the ONI is based on the area plus and minus five degrees of Latitude. The water south of the Equator is not as warm as the water right on the Equator. Last week I had thought that this warm event may have reached its peak intensity. I was wrong. One week has very little significance but it will be interesting to monitor and the above graphic updates daily so one can basically monitor this on a daily basis.
Here is another way of looking at it.
This Hovmoeller shows that in recent months we had a warming of the Central Pacific (Modoki) which has recent moderated (Anomaly in Nino 4.0 declining) a bit in intensity but has spread out and may be reintensifying. Starting in April, the Eastern Pacific warmed (Canonical El Nino) as the current Kelvin Wave arrived there. Of interest, the warming in the Eastern Pacific occurred last year at about this same time or slightly later. It did not extend into Fall of last year. So you can see why I am skeptical about any interpretation made by NOAA. But clearly the warm anomaly in the Eastern Pacific is strengthening which is not surprising given the progression of the current Kelvin Wave.
The key question really is the issue of the inventory of warm water: both the surface and subsurface down to 300 meters. The Faux El Nino this past winter did dissipate heat from the ocean into the atmosphere. Is there enough heat left to sustain this Warm Event? I suspect not but we will see.
All predictions about El Nino for next winter must be tempered by what is called the Spring Prediction Barrier (SPB). Nevertheless, El Nino conditions impacting the first half of this coming winter are very likely but the intensity of the El Nino conditions remains to me an open question. Since we are already in June, the SPB relates to the JAS prediction of the intensity of the El Nino during this period of time. Based on the available data, the SPB may surprisingly not impact the OND forecast very much but may again come into play relative to the JFM forecast. So the duration of this Warm Event also for me remains an open question. The errors are usually over prediction of intensity rather than under prediction.
Greater than single-winter warm events are fairly rare. I looked at the NOAA list of El Ninos declared since 1950 and there are 19 of them and only two lasted through two winters. One started at the time of year that this Warm Event first reached a ONI 0.5 level and one started later in the season. Both were during a period later recognized as PDO+. So I am just wondering if there is a reason to assume that this particular Warm Event has the staying power of the former champions. The PDO is currently positive but not as positive as recently and what has occurred so far re this Modoki Type II in terms of geographical coverage of warmer water has been minimal so the dissipating impacting may have been sufficiently minimal to allow this event to make it through this winter. I will be surprised if that happens but I have been surprised before.
Pulling it All Together.
We are in El Nino conditions now. The length and intensity of this El Nino is still not clear mostly in terms of whether or not it will extend into the early part of 2016. We may or may not have a Pacific Climate Shift as the PDO+ may be simply related to the Warm Event (and quite frankly at this point appears to be). But for now we do have PDO+. The AMO being an overturning (see below) may be more predictable so the Neutral status moving towards AMO- is probably fairly reliable but not necessarily proceeding in a straight line. So none of this is very difficult to figure out actually if you are looking at say a five-year forecast.The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report which you can get to below. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.
Additional Information on Low-Frequency Ocean Cycles
Click Here for the Global Economic Intersection Weather and Climate Report. Page II where you will find:
My Editor tells me that he will show me how to create a Table of Contents for Part II to make it easier to navigate.
Click Here for Page III which deals with Global Warming.
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