Econintersect Climate and Weather Update, 15 September 2014
Written by Sig Silber
The NOAA "analogs" and information from around the world suggest that we have at least some characteristics of El Nino weather right now. But the El Nino is not here and may not get here.
So what is that all about?
Well actually I wrote that title last week when the analogs were all showing that we were in El Nino weather (meaning that is how the forecasters interpreted the situation). On Friday that changed and all the analogs showed La Nina. That persists with today's forecast from NOAA. But I am not going to fall into their trap of changing the title and then having them tomorrow (when this article is published) reverse their take on the analogs. So I am leaving my title alone and awaiting NOAA having an attitude adjustment.
More seriously, one wonders how we can have an El Nino on the way and be experiencing La Nina weather conditions. So my title is meant to be provocative. The obvious explanation is that there may be an El Nino but it is not here yet. But sometimes El Nino weather shows up prior to the El Nino. Last week that looked to be the case.
With NOAA they never look back and never offer excuses so I have no idea why they changed their minds re the analogs other than they are interpreting the data and whatever that data is showing and the models are telling them, they report. What is confusing is the high levels of confidence they have been showing in their reports when the forecasts keep changing. But to NOAA, confidence is mostly a measure of the agreement among the models.
If this discussion is confusing it is intentional. Our system of weather forecasting needs to be improved. When what appears to be El Nino conditions suddenly becomes La Nina Conditions, I think that deserves an explanation. We may get that Thursday when the new seasonal forecast comes out.
Let's take a close look at the 6 - 14 day outlook issued today September 15 for the U.S.
I am only showing the "second week" namely the day 8 -14 outlook. The first week can be found in Part II of my report but 8 - 14 days already covers most of the 6 - 14 day period.
8 - 14 Day Outlook
Notice that with respect to temperature, there is a real divide between the West and the East although the Southeast is also projected to be warmer than climatology. With respect to precipitation, the divide is North to South or perhaps more accurately Northwest to Southeast. Some explanation of this might be found in the "analogs" discussed below.
Now let us take a more 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.
What are they telling us today?
|1955 Sept 8||La Nina
|1955 Sept 9||La Nina||-||+|
|1973 Sept 15
|1974 Sept 10
|1974 Sept 12||La Nina||-||-
|1984 Sept 28||La Nina||+||-|
|1995 Sept 13||La Nina||+||Neutral
|2007 Sept 10||La Nina||-||+|
|2008 Sept 13||Neutral||-||+||Just before a weak La Nina
|2008 Sept 15||Neutral||-||+||Just before a weak La Nina|
One thing I noticed right away was the pairs of analogs which indicates that the weather situation was fairly stable i.e. looking at 4 days ago and 3 days ago does not present a dramatically different view. That is a bit different than the past few weeks so it looks like we are in a more stable pattern at least in terms of how it looks to the forecasters.
Last week the analog analysis seemed to reflect a shift in the phase of our ocean cycles from PDO-/AMO+ which is the opposite of the pattern that has been in place this first part of the 21st Century. This week the analogs reflect PDO- with no clear pattern for the AMO. I checked the monthly values for the PDO and AMO (there may be weekly values but I do not have access to them) and the PDO remains+ but less so than in some recent months and the AMO appears to be moving back to AMO+. These are noisy data series which is why they are not used for forecasting purposes but mostly for postmortems.
It has seemed to me that it was too soon based on historical lengths of these cycles for the PDO to go positive but that data series is also very noisy, we do not have many data points, and the PDO is an imperfect index. But I still think it is useful to think about what if one or the other of these cycles has changed phase. If they have not now, they will within a decade or two. At this point I am not willing (because I am not able) to predict when such a change will occur but I am able to predict what the impact would be and that is shown below.
You can see from the McCabe et al maps shown below that we may be in for a major change in where drought is likely.
The key maps are shown below:
Drought frequency (in percent of years) for positive and negative regimes of the PDO and AMO. (A) Positive PDO, negative AMO. (B) Negative PDO, negative AMO. (C) Positive PDO, positive AMO. (D) Negative PDO, positive AMO.
El Nino Update.
Australia issued an update September 9
"El Niño remains possible in 2014
Issued on Tuesday 9 September 2014
Despite some warming of the tropical Pacific Ocean over the past month, ENSO remains neutral. However, models continue to suggest an El Niño remains possible in 2014, and hence the Bureau’s ENSO Tracker remains at WATCH status, indicating at least double the normal risk of an El Niño developing by the end of the year.
Although tropical Pacific Ocean surface temperatures are within neutral range, an area of the sub-surface is warmer than average. A late season El Niño remains possible if these warmer waters rise to the surface and then affect atmospheric circulation, or if another sustained westerly wind burst develops in the western Pacific.
The majority of international climate models surveyed by the Bureau indicate central tropical Pacific surface temperatures will remain warmer than average, and may exceed El Niño thresholds by the end of the year. These model outlooks and current observations mean the Bureau’s ENSO Tracker remains at WATCH status, indicating at least a 50% chance (double the normal likelihood) of an El Niño forming in 2014.
El Niño is often associated with below-average rainfall over large parts of southern and eastern inland areas of Australia and above-average daytime temperatures over southern Australia. Such impacts can often occur while an event is developing, as experienced in some locations over the past several months.
The negative Indian Ocean Dipole (IOD) in the tropical Indian Ocean has shown signs of weakening. Waters to the north of Australia and in the Timor Sea have cooled over the past two weeks. All climate models surveyed by the Bureau indicate the IOD will continue to weaken, with neutral conditions likely to return during the austral spring."
Let us look at the latest NOAA Hovmollers.
First Sea Surface Temperatures
The way to read these graphics is from top to bottom where the top represents the past and the bottom the current situation. It is like a plotter and in the past that is probably how these graphics were produced. I do not see anything to write home about here. Looks pretty much the same as last week. But over at 160E right at the bottom there is a hint that next week this graphic may be more interesting. You can see why that may be the case in the next two graphics.
And now the low-level wind anomalies.
Again I am not impressed. I see some action that could help move the below Kelvin Wave to the East but I also see the reverse action in the Eastern Pacific which is not noted on the Hovmoller diagram.
And then the third ((there are more than three but I focus on three) part of the equation. Kelvin Waves.
And here we do have a strong and increasing signal of warm water moving east and getting warmer as it goes. Notice looking up at earlier dates that some Kelvin Waves fizzle out but this one does not seem to be fizzling out. I believe that this Kelvin Wave is the major reason for continued optimism that we will have an El Nino this year but it will be late arriving.
It is really over but by convention, tropical storm activity that forces moisture into the U.S. Southwest is credited to the Monsoon for accounting purposes. So we have one more week of monsoon moisture potential due to Odile. This year I believe there were no named hurricanes impacting the east coast. hmm. I thought Global Warming was going to improve east-coast surfing. What a disappointment!
- NOAA and other agency graphics (including international agencies) that auto update. So this includes both short term- and seasonal "updates". It will ALWAYS be up to date even if my commentary on the graphics is not. I update my commentary when it seems necessary and certainly every Monday but some of these graphics auto update every six hours.
- Economic and other Impacts of major weather events. Not sure there is any other place to obtain this information consistently other than very specialized subscription services.
- Information on Climate Cycles both those which are fairly short term i.e. less than a decade in duration and multi-decadal cycles.
- Economic and other Impacts of those Climate Cycles which are referred to by the IPCC as Internal Variability as opposed to secular Climate Change which is always in the same direction. Again I am not sure if there is another source for this information where it is pulled together in one place as I have.
- Information on Anthropogenic Global Warming science i.e. the secular change in our climate that overlays both short term weather and historical climate cycles as well as black swan events like volcanic eruptions. I prefer to call this Global Warming as it is the warming that triggers the other changes.
- Economic and other Impacts of Global Warming. The IPCC AR5 WG2 attempts to describe and quantify these and I have some excerpts from their report. Over time I will go beyond their report.
For now this is all in one article which may be a little difficult to navigate but that will soon change and the information will be accessed easily by topic.