October 28th, 2014
Written by Sig Silber
Some signs that El Nino is planning to arrive are appearing in the Hovmollers. But in the near term, the weather pattern is solidly showing La Nina conditions. There are no signs yet of the negative AO or NAO, but that has not been predicted to occur until later in the winter.
This El Nino, if it occurs, may last longer than some think, but may not produce the impacts that NOAA has been predicting. It is a very complicated situation. New information is available on the evolution of the Atlantic Multi-decadal Oscillation (AMO) and will be reviewed this week.
First let us take a look at the 8 - 14 day outlook that was issued today October 27.
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 covers most of the 6 - 14 day period and does not vary much from the first part of the outlook issued today.
Here is the Early Temperature Outlook for the single month of November.
There is not a lot of resemblance between the 8 - 14 Day Outlook and the November full month outlook. Of course a month forecast does not necessarily agree with a 9 day portion (the 6 - 14 day outlook of which I am only showing here the 8 - 14 day map) but this does seem to be unusual.
And here is the 8 - 14 Day Precipitation Outlook issued today.
And here is the Precipitation Outlook for November issued on October 16.
The Outlook for the first third of the month is almost the exact opposite of the full month outlook. Do we have a parallel universe? Most likely we have a seasonal transition which has not yet taken place. We may know more on October 31 when the November Early Outlook is updated.
From the NOAA Discussion:
6-10 DAY OUTLOOK FOR NOV 02- 6 2014
TODAY'S MODEL SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE EXPECTED 500-HPA CIRCULATION PATTERN FOR THE 6-10 DAY PERIOD OVER NORTH AMERICA. MOST MODEL SOLUTIONS AGREE ON THE PLACEMENT OF A TROUGH OVER THE NORTH PACIFIC OCEAN. ANOTHER TROUGH IS FORECAST OVER THE WESTERN CONUS. DOWNSTREAM OF THIS TROUGH, RIDGING IS FORECAST OVER THE EASTERN CONUS. THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE LOW TO MODERATE SPREAD ACROSS THE MAJORITY OF THE FORECAST DOMAIN. MORE WEIGHTING WAS GIVEN TO THE 0Z ECMWF ENSEMBLE MEAN BASED ON ITS SKILL DURING THE PAST 60 DAYS AS ASSESSED BY 500-HPA HEIGHT ANOMALY CORRELATIONS.
WESTERLY TO SOUTHWESTERLY UPPER LEVEL FLOW OVER THE CONUS LEADS TO ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE NATION EXCEPT FOR THE EAST COAST AND SOUTHERN CALIFORNIA WHERE NEAR-NORMAL TEMPERATURES ARE INDICTED CONSISTENT WITH GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLES. SOUTHERN ALASKA AND THE ALASKAN PANHANDLE ARE EXPECTED TO BE UNDER A 500-HPA TROUGH, FAVORING BELOW-NORMAL TEMPERATURES, WHILE NEAR- TO ABOVE-NORMAL TEMPERATURES ARE EXPECTED OVER NORTHERN ALASKA AND THE ALEUTIANS.
TROUGHING OVER THE NORTH PACIFIC OCEAN WITH AN ENHANCED PACIFIC JET FAVORS ABOVE-MEDIAN PRECIPITATION FROM THE PACIFIC NORTHWEST TO THE UPPER GREAT LAKES. ABOVE-MEDIAN PRECIPITATION IS FAVORED OVER PARTS OF THE SOUTHERN PLAINS, THE LOWER MISSISSIPPI VALLEY, THE OHIO VALLEY, THE GREAT LAKES, THE MIDDLE ATLANTIC AND THE NORTHEAST, AHEAD OFTHE TROUGH FORECAST OVER THE WESTERN CONUS. NEAR- TO BELOW-MEDIAN PRECIPITATION PROBABILITIES ARE ENHANCED FOR THE SOUTHWEST, MUCH OF ALASKA, AND FLORIDA CONSISTENT WITH NAEFS AND GEFS REFORECAST GUIDANCE.
8-14 DAY OUTLOOK FOR NOV 04 - 10 2014
THE ENSEMBLE MEAN PREDICTIONS OF THE 500-HPA HEIGHTS FOR THE WEEK-2 PERIOD ARE IN FAIRLY GOOD AGREEMENT OVER NORTH AMERICA. MOST MODEL SOLUTIONS PREDICT A TROUGH OVER THE NORTH PACIFIC OCEAN. A GENERALLY ZONAL FLOW PATTERN IS ANTICIPATED OVER MOST OF THE CONUS. MORE WEIGHTING WAS GIVEN TO THE GFS SUPERENSEMBLE MEAN BASED ON ITS SKILL DURING THE PAST 60 DAYS AS ASSESSED BY 500-HPA HEIGHT ANOMALY CORRELATIONS.
THE MOSTLY ZONAL UPPER LEVEL FLOW OVER THE CONUS LEADS TO ELEVATED CHANCES FOR ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE NATION EXCEPT FOR MOST OF CALIFORNIA WHERE NEAR-NORMAL TEMPERATURES ARE INDICTED, CONSISTENT WITH GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLES. SOUTHERN ALASKA IS EXPECTED TO HAVE BELOW-NORMAL TEMPERATURES, WHILE NEAR- TO ABOVE-NORMAL TEMPERATURES ARE EXPECTED OVER NORTHERN ALASKA.
THE WEEK-2 PRECIPITATION PATTERNS ARE SIMILAR TO THOSE FOR THE 6-10 DAY PERIOD. TROUGHING NEAR THE NORTH PACIFIC OCEAN WITH AN ENHANCED PACIFIC JET FAVORS ABOVE-MEDIAN PRECIPITATION FOR THE PACIFIC NORTHWEST AND THE NORTHERN GREAT BASIN. ABOVE-MEDIAN PRECIPITATION IS FAVORED OVER PARTS OF THE SOUTHERN PLAINS, THE LOWER MISSISSIPPI VALLEY, THE OHIO VALLEY, THE GREAT LAKES, THE MIDDLE ATLANTIC AND THE NORTHEAST. NEAR- TO BELOW-MEDIAN PRECIPITATION PROBABILITIES ARE ENHANCED FOR THE SOUTHWEST PARTS OF THE CONUS CONSISTENT WITH NAEFS AND GEFS REFORECAST GUIDANCE."
Analogs to Current Conditions
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?
|1971 November 10
|1973 November 9
|1973 November 10
|1981 October 6
|1989 October 23
|1998 October 11
|1998 October 12
|2005 October 16||La Nina||-||+|
|2007 October 10||La Nina||-||+|
The analogs are providing a consistant picture of La Nina conditions. They also reflect PDO negative conditions even though the PDO is positive. So I do not know what the analogs are telling us about the future but they are consistent with the 6 - 14 day outlook.
El Nino Discussion
A. From Australia
Issued on Tuesday 21 October 2014
El Niño–Southern Oscillation (ENSO) indicators, as well as Australian rainfall patterns, continue to show some El Niño-like signatures, but remain in the neutral range.
The tropical Pacific Ocean has remained warmer than average for more than six months, while the Southern Oscillation Index has remained negative since early June. However neither has reached typical El Niño levels for any sustained period, and only weak atmosphere-ocean coupling appears to have taken place so far.
International models surveyed by the Bureau suggest that warmer-than-average tropical Pacific waters are likely to persist. While there has been some easing in model outlooks over the past month, three of eight models reach El Niño thresholds by January and another two remain just shy of the thresholds for an event.
Australia has generally been dry and warm over recent months. A warmer central tropical Pacific late in the year typically heralds warmer and drier conditions for parts of eastern Australia, as well as a reduction in the number of tropical cyclones in the Australian region and increased bushfire risk in the south.
The Indian Ocean Dipole (IOD) is likely to remain neutral. The IOD typically has little influence on the Australian climate from December to April.
Next update expected on Wednesday 5 November 2014 | print version"
B. Now let us look at the latest NOAA Hovmollers.
First Sea Surface Temperatures
Over to the left side of the graphic at 160E at the bottom you can see where there had been some warming surface water. It is now less impressive but does now appear to be moving to the east. There was just the barest of hint of that last week. Also you see more pockets of warmer water further east.
And now the low-level wind anomalies.
We had a westerly anomaly last week that could do something and apparently it did. Is that enough to actually have an El Nino with enough strength to have an impact?
The Southern Oscillation Index (SOI) has definitely been cooperating and you can find the daily and 30 and 90 day averages here. With the SOI there is always a cause and effect issue. Is the SOI a cause of or a result of warm water being to the east? The SOI is an imperfect index as the two reference points are not on the Equator but I will not go into that today. The 30 day average is now marginal for El Nino conditions. Today's reading is -10.64 which is an El Nino reading but less so than in the past week. You can not deduce anything from one day but it reminds us that situations can change rapidly.
C. And then the third part of the equation (there are more than three but I focus on three): Kelvin Waves.
And here we do have a signal of warm water moving east but it does not have the intensity of the the Kelvin Wave earlier this year. Notice looking up at earlier dates that some Kelvin Waves fizzle out but this one does not seem to be fizzling out but continues to progress east. It is important to remember that warm water at the surface is more prone to evaporate thus transferring heat from the ocean into the atmosphere and thus dissipating the warm water anomaly at the sea surface. That is one reason why the El Nino phase of ENSO is generally short lived.
I believe that this Kelvin Wave is the only reason for continued optimism that we will have an El Nino this year but it will be late arriving if it arrives at all. At some point we would have expected to see the upwelling phase showing on this graphic which indicates the reversal of the surface warming and probably the termination of this El Nino or its transformation into a Modoki i.e. a Central Pacific El Nino which behaves very differently in terms of weather impacts than a traditional/canonical El Nino. So far there is no sign of an upwelling wave, just a period of more or less neutral conditions, and now a second downwelling wave is both evident and this week is now highlighted by NOAA. The wave that has been focused on in prior reports to me has not moved to the east significantly in the past week. All the information is right there on the chart as reading from top to bottom is showing the passage of time.
This newly identified Kelvin Wave appears to be about the same intensity as the previous one and is likely to impact things in two or three months. So to me this looks more like a weak version of the 1982/1983 El Nino and may last longer than NOAA thinks but have different impacts than they think also. We shall see. I am still thinking the Japanese (and the Australians) sized this up from the start and that this is really more like a Modoki than a traditional El Nino and that weather patterns will be shifted some number of degrees further west than would be the case for a traditional El Nino. The forecast for a negative Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) also to me fits with that interpretation. We shall see.
I still do not see a traditional El Nino of any significant strength likely to happen this winter, especially the first half of the winter. It appears to be a very complicated situation. There are many possibilities on the table in my opinion:
- A short weak traditional El Nino which arrives late. (The NOAA projection)
- A weak traditional El Nino arriving late but being reinforced and turning into a long lasting stronger traditional El Nino. (Not forecast by NOAA but not inconsistent either) This would be somewhat like the 1982/1983 Super El Nino.
- A weak traditional El Nino that turns into a Modoki next year (The Japanese Forecast)
- Nothing much at all at least until next summer (seems to be where the Australia model is headed)
- Other variations of the above all related to warmer water further east than usual in the ENSO cycle but not necessarily translating into the usual El Nino that would normally be here now if it fit the usual mold.
A new paper is out. Unfortunately I can only access the abstract. Some with subscriptions may find the full paper here.
Klöwer et al. (2014) Atlantic meridional overturning circulation and the prediction of North Atlantic sea surface temperature.
• North Atlantic sea surface temperature exhibits high decadal predictability potential.
• Model bias hinders exploiting the decadal predictability potential.
• An innovative method was developed to overcome some of the bias problem.
• North Atlantic sea surface temperature will stay anomalously warm until about 2030.
The Atlantic Meridional Overturning Circulation (AMOC), a major current system in the Atlantic Ocean, is thought to be an important driver of climate variability, both regionally and globally and on a large range of time scales from decadal to centennial and even longer. Measurements to monitor the AMOC strength have only started in 2004, which is too short to investigate its link to long-term climate variability. Here the surface heat flux-driven part of the AMOC during 1900–2010 is reconstructed from the history of the North Atlantic Oscillation, the most energetic mode of internal atmospheric variability in the Atlantic sector. The decadal variations of the AMOC obtained in that way are shown to precede the observed decadal variations in basin-wide North Atlantic sea surface temperature (SST), known as the Atlantic Multidecadal Oscillation (AMO) which strongly impacts societally important quantities such as Atlantic hurricane activity and Sahel rainfall. The future evolution of the AMO is forecast using the AMOC reconstructed up to 2010. The present warm phase of the AMO is predicted to continue until the end of the next decade, but with a negative tendency.
And then there is this paper.
On the observed relationship between the Pacific Decadal Oscillation and the Atlantic Multi-decadal Oscillation Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison, USA; Laboratory of Climate, Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Science, Peking University, Beijing, ChinaJournal of Oceanography (Impact Factor: 1.46). 01/2011; 67(1):27-35. DOI: 10.1007/s10872-011-0003-x
ABSTRACT We studied the relationship between the dominant patterns of sea surface temperature (SST) variability in the North Pacific
and the North Atlantic. The patterns are known as the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO). In the analysis we used two different observational data sets for SST. Due to the high degree of serial correlation in the PDO and AMO time series, various tests were carried out to assess the significance of the correlations. The results demonstrated that the correlations are significant when the PDO leads the AMO by 1 year and when the AMO leads the PDO by 11–12years. The possible physical processes involved are discussed, along with their potential implication for decadal prediction."
Of course the correlation coefficients in the above paper are under 0.5 on an individual lag period basis so although the argument for a somewhat predictable lag is strong the exact number of years is far less certain. The above paper was published in 2010. I am not sure how to integrate the two papers. Figure 1 in the paper is confusing to me so I have to sort that out. Have they plotted the PDO in reverse i.e. negative Phase plotted as a positive number? If so then it makes sense. The PDO would appear to be possibly switching from negative to positive.
Here is a similar paper published in 2007. Both papers are excellent in that they attempt to explain the mechanism for the synchronization not just depend on mathematical analysis. They both arrive at similar conclusions. In this paper, the most highly correlated lag is 13 years.
In both cases the problem becomes complex because both the PDO and AMO have multiple sub-oscillations within them. It is reported as being a single phenomenon but clearly it is not. So the various sub-oscillations may be linked by different mechanisms. In some cases, the Atlantic may be driving the Pacific but in other cases the Pacific may be driving the Atlantic. There is then the question of when did the Atlantic go into its positive phase i.e. AMO+? If this was around the turn of the century, then perhaps it is time for the PDO to change phase.
There are a lot of "ifs" in all of this so it is quite a challenge to sort this all out. I will be publishing my analysis of the most likely scenarios for the succession of the AMO/PDO phase combinations some time soon. It is obviously very important for 5 to 50 year planning. I totally believe in Global Warming so that is another factor that needs to be taken into account plus the less than 150 years of good data on these cycles.
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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.