posted on 03 March 2015
Written by Sig Silber
NOAA issued their March Update on February 28. It does not say much that is very different from the February 19th report other than that the Plains States will have a delayed Spring. But much has changed since last week and a casual glance at some of the graphics in this report including the jet stream and the position of highs and lows will reveal a lot about those changes beyond that which is in the NOAA discussion. A seasonal shift is in progress; the Aleutian Low has moved over to the Russian side of Beringia and is disappearing and the RRR has dramatically changed its location. Winter is over!
This is my weekly Weather and Climate Update Report. A more complete report can be found here in what I call Page II of my Weekly Report.
Here are excerpts from the updated March Outlook discussion issued on Saturday February 28, 2015
Here are selected excepts from the NOAA Discussion issued on Thursday February 19 in conjunction with their updated Seasonal Outlook. I have retained these excerpts from last week's report as I think they are relevent. I have deleted much of the prior excerpts because NOAA is no longer marketing its ImagiNino so it is no longer necessary to highlight where they have been going wrong.
Let us now look at the maps both those issued Saturday and those issued just nine days earlier.
First the Early March 2015 Temperature Outlook Issued on February 19, 2015
And then the Updated March, 2015 Temperature Outlook Issued February 28, 2015
In the map above I have drawn a line to show the colder than climatology in the Plains States from North Dakota down to Texas added since the February 19 issuance
And now Precipitation
Early March Precipitation Outlook Issued February 19, 2015
And then the Updated March 2015 Precipitation Outlook Issued on February 28, 2015
Either they are real good or someone was on vacation as there is hardly any change in the updated Precipitation probability map since the Early Update nine days earlier.
Now let us shift gears and discuss the Short-term Outlook that was issued today March 2, 2015. It will auto-update every day so it will be changing day by day (and thus be up to date whenever you elect to read this report) but my comments as well as the comments of NOAA may become out of sync with the map since these comments do not auto-update.
Generally I only show the "second week" namely the 8 -14 Day Outlook. The first week (6 - 10 Day Outlook) together with much additional information on current weather patterns and near-term forecasts can be found in Part II of my report, but 8 - 14 days covers most of the 6 - 14 day period.
Here is the updated March Temperature Outlook Issued February 28, 2015 and previously shown earlier in this report.
And here is the 8 - 14 Day Temperature Outlook.
The Temperature Outlook for the second week of March is not totally consistent with the Monthly Outlook but you can see how it might evolve consistent with the Monthly Outlook.
Here is the updated Precipitation Outlook for March issued on February 28, 2015 and also shown earlier.
And here is the 8 - 14 Day Precipitation Outlook issued today March 2, 2015.
The Precipitation Outlook for the second week of March is a bit inconsistent with the Monthly Outlook except for Alaska. It may be useful to view the Outlook in terms of the Northern Tier and Southern Tier of CONUS as there are different factors involved in the Outlook.
Here are excerpts from the NOAA release today March 2, 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.
This is a big change from last week. There is only one El Nino analog and many classify it as a Modoki. The other analogs are ENSO Neutral or La Nina. The dates of the analogs are all over the place from February 12 to March 11 perhaps signifying a variety of historical conditions spanning early and late transitions to Spring. The Ocean Phases are primarily PDO Negative and AMO Negative and over a multiple year period such conditions are highly correlated with Condition B in the below graphic.
Red is a high likelihood of drought, blue the opposite. So the ocean conditions in the analogs would suggest perhaps a wetter Outlook but the above graphic relates mostly to winter and we are in a transition period.
Back to the Current Situation:
Sometimes it is useful to take a look at the location of the Jet Stream or Jet Streams.
And sometimes the forecast is revealing. Below is the forecast out five days. You can see a major shift taking place in the pattern for later this week essentially cutting off the cold air intrusions into CONUS from the North.
To see it in animation, click here.
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. One can imagine that attempting to forecast this 6 - 14 days out is quite challenging.
And below is another view which highlights the surface highs and the lows re air pressure on Day 3. You can see how the counter-clockwise Aleutian Low has moved west towards Russia and weakened (for a low that means the air pressure has increased). The RRR is still there but further offshore thus allowing storms to form or drop down and temporarily move off the Coast of California and acquire moisture.
And here is Day 6. The Aleutian Low is nowhere to be seen signifying the end of Winter.
I interpret the above as moving towards a more Spring-like pattern that will manifest itself moving from west to east.
El Niño Discussion
Because NOAA has finally acknowledged that the "ImagiNiño" has no impact on their Outlooks (even though it should as it is a Modoki) I am truncating my ENSO Report.
It is useful to understand where ENSO is measured.
Of most interest to NOAA is 120 W to 170 W labeled Nino 3.4 as that is where the ONI Index is measured. More information can be found here.
And now the low-level wind anomalies.
This shows some change from last week. Notice the blue area between 150E and 170W. That indicates stronger than usual Easterlies. But you can also more clearly see the area between 140W and 170W where last week there might have been a hint of weaker Easterlies and now that is very clear. The Southern Oscillation Index (SOI) this week it is clearly consistent with ENSO Neutral or possibly even La Nina conditions. You can find the daily and 30 and 90 day averages here. The 30 day average of +0.01 is certainly not consistent with El Nino conditions (a 30 day average of -8.0 or more negative is considered to be consistent with El Nino conditions). Today's reading of +5.4 is more consistent with La Nina than El Nino. The SOI fluctuates based on local weather conditions in Tahiti and Darwin Australia which is why the 30 and 90 day average are more significant than the daily values. The 90 day average is currently -5.33 which is not sufficiently negative to be considered consistent with El Nino conditions.
I thought I would also show what I call the Kelvin Wave graphic again this week. It is really the Upper Ocean Heat Anomaly.
You can easily see that the this Kelvin Wave has continued its progression eastward. Remember the bottom of the graphic is the current readings and as you look up you see basically day by day the historical progression of these waves. If you look out by 170 E you see the very slow playing out of this downwelling process and perhaps way out there at 140E there may be the start (in blue) of the next upwelling cooling phase. That is just a guess at this point but in a couple of weeks it will be clearer one way or another. What counts is the shades of red so it also looks to me like the strongest part of this Kelvin Wave is starting to play out. Remember that part of the Tropical Pacific is unusually warm this year to begin with so it does not take much to register as a positive anomaly. But what is most important is the cold area over to the East which is what makes this a Modoki rather than a traditional El Nino. We still have upwelling of cold water off of Ecuador so they see no sign of an El Nino. And fishing there is not negatively impacted by an El Nino.
And finally the latest model results released by NOAA on March 2, 2015.
This graphic is a modified version of the graphic that appears on Page II of this Report. It is modified by NOAA to be consistent with the maps on the right which can be found here. Those maps have been processed to adjust for the observed skill of the models. I probably could do a better job with triangles but just by eyeballing this chart it looks like it is showing an ONI reading of about 0.7 forecast through the Spring. I believe that NOAA has again reported a weekly ONI of 0.5. To me this chart is increasingly amusing. When I see a computer model that is providing a current reading for the ONI of 0.7 when NOAA is reporting actually values for three weeks of 0.5, I roll my eyes. So this may say it is a "corrected" model but to me I have to really wonder about the calibration of the process. Also it is showing higher ONI values going into the summer. That may turn out to be correct but given the Spring Prediction Barrier I would think that NOAA might have wanted to put a footnote on that in the graphic.
If the SSTA in NINO 3.4 was your only criteria, the recent readings released by NOAA of 0.5 for the ONI would be considered a marginal (and that would be in the strictest use of the term marginal since greater than or equal to 0.5 is the criteria) El Nino but the other factors have not fallen into place. And this model does not attempt to classify the type of El Nino which is very important in terms of weather impacts. Notice the model is forecasting higher ONI levels as we move into the summer. It is difficult to read the maps to the right but the upper left map is the forecast for March/April/May and it looks more like a Modoki Type II than a traditional El Nino to me. The further-out maps do look like an El Nino. Are we going to have a traditional El Nino next year?
Below is another graphic that confirms that we are not in a traditional El Nino but perhaps a borderline El Nino Modoki. The top graphic shows surface temperatures and wind direction and speed conditions 10 degrees north to 10 degrees south of the Equator and this is one of the most up to date sources of information available. The bottom graphic shows anomalies.The bottom graphic shows the deviation from average conditions. You can see many things in this graphic. First of all in the second of this pair of graphics which is the anomalies, you can see the pockets of warm water which are in some cases greater than 1C above average and in other cases below 0.5C above average conditions. West of 170W in the Nino 4 area you have warm water on the Equator which is consistent with a Modoki Type II. It is moving East and may be what the computer models are noticing. Looking between 170W and 120W on the Equator, you see a large area where the anomaly is under 0.5C. And you also see an area above 0.5C which is increasing in size again possibly explaining the CFS.v2 model results. But this is mostly due to the current Kelvin Wave and is temporary. Presumably the computer models are assuming this current Kelvin wave will trigger a feedback loop leading to an ever strengthening El Nino. That is not very realistic. In the Nino 1+2 Area over by Ecuador, one can see a positive anomaly i.e.colder water. This area of colder water has expanded both above and below the equator. That does not figure in to the ONI calculation but determines the type of El Nino that we have and the impact it has on weather. To have a strong El Nino that has a significant impact on weather, you need temperatures there in excess of 28C. In the upper part of the below graphic it looks like the water temperature off of Ecuador is about 26C. The analysis of the wind anomalies in the Eastern Pacific (the second of this two-image graphic) generally points strongly (long arrows) to the west which is the opposite of what you would expect with a traditional El Nino. Not shown here but the warm water off the Northwest Coast of the U.S. is also consistent with a Modoki Type II.
Pulling it All Together. .
So this continues to look to me like a warm event that is not a full-fledged El Nino and is not a traditional El Nino. So the expected impacts are different than the expected impacts from a traditional El Nino. Whatever this pattern is, it is not very different from ENSO Neutral. I am still thinking the Japanese sized this up from the start and that this is really more like a Modoki than a traditional El Nino and that weather patterns are shifted some number of degrees further west (or possibly rotated) than would be the case for a traditional El Nino which is why the weather where I live is more typical of a La Nina than an El Nino. This is characteristic of an El Nino Modoki in the U.S. Southwest. The increased frequency of Modokis has been the case since the PDO went into its Negative Phase in 1998/1999 which is why a possible change to PDO Positive is so very important. Where I live it would end the drought but of course it would initiate drought elsewhere. An extensive discussion of the PDO is found here in Part II of this report.
I do not see a traditional El Nino of any significant strength likely to happen this winter (which is essentially over) although a "near" El Nino appeared in January to be making its presence known to a limited extent but mainly outside of the U.S. That no longer appears to be the case for March. It remains a complicated situation mostly because of the at least temporary shift of the configuration of the Pacific with respect to the location of warm and cold water to a configuration which is called PDO Positive (+) combined with the Blocking Ridge off the West Coast.
An El Nino Watch for next year might be in order as there remains a lot of warm water in the Warm Pool but usually it takes a few years for that to built up sufficiently for another warm event to get under way. ENSO Neutral is where some of the models are headed and I suspect that they have it correct for next winter. But if the PDO has indeed switched to its Positive Phase we should expect a powerful El Nino soon. It could be next winter.
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