December 1 Weather and Climate Report – It is Starting to Look a Lot Like El Nino

Written by Sig Silber

It may be weak and the Hovmoller analysis, analogs analysis, and some other information published by NOAA is not encouraging. But there are definitely signs of an El Nino both the updated Outlook for December issued on Sunday and in the actually weather patterns that are occurring. Thus NOAA which launched its El Nino campaign perhaps two months early is now in a position where the weather has caught up to their forecast. Calibrating the Seasonal Outlook to the strength and other characteristics of this El Nino will remain a challenge made a bit easier as it seems to be weak but at this point a traditional El Nino.

Here is the Early December Temperature Outlook issued on November 20.

And here is the Updated December Temperature Outlook released Sunday.

This is a big change in 10 days for the same period of time namely December.

Here is the Early December Precipitation Outlook issued on November 20.

And here is the updated December Precipitation Outlook released Sunday.

Notice a small area of drier than climatology has been added to Montana and the wetter than climatology for the Southeast has been removed from the Outlook for December.

And here is the discussion:

“30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2014

THE DECEMBER 2014 OUTLOOK REMAINS CHALLENGING, THOUGH FOR SOMEWHAT DIFFERENT REASONS THAN THOSE DISCUSSED BELOW FOR THE 0.5 MONTH LEAD OUTLOOK. A DRAMATIC PATTERN CHANGE IS ANTICIPATED ACROSS THE NORTH-CENTRAL CONUS, WHERE MUCH BELOW-NORMAL TEMPERATURES FOR THE FIRST COUPLE DAYS OF THE MONTH ARE FORECAST TO BE REPLACED BY ABOVE-NORMAL TEMPERATURES THROUGH AT LEAST THE SECOND WEEK OF THE MONTH. A SIMILAR SITUATION IS FORECAST FOR THE NORTHEAST, WHERE A SERIES OF CANADIAN HIGHS ARE FORECAST TO DOMINATE SURFACE CLIMATE EARLY. THE ARCTIC AIR IN CANADA EARLY IN THE PERIOD IS THUS EXPECTED TO PROGRESS MORE EAST THAN SOUTH, AS A +NAO CIRCULATION IS EXPECTED EARLY IN MONTH. THIS LEAVES AREAS TO THE SOUTH MILDER THAN CLIMATOLOGY FOR MOST OF THE FIRST 10 DAYS OF THE MONTH OR SO.

IN THE MEDIUM RANGE PERIOD, THE MODELS ARE IN GOOD AGREEMENT THAT AN ANOMALOUS  TROUGH WILL FORM IN THE NORTH PACIFIC, THOUGH THERE IS SOME DISAGREEMENT AS TO ITS LONGITUDINAL CENTER. THE GLOBAL ENSEMBLE MEANS INDICATE A FAIRLY LONG WAVELENGTH PATTERN, APPEARING AS A HYBRID OF THE CANONICAL +PNA AND LOW-FREQUENCY ENSO FOOTPRINT. THE LATTER REMAINS SUSPECT AS THE EXPECTED CONVECTIVE RESPONSE TO EL NINO IN THE CENTRAL PACIFIC REMAINS TENUOUS.

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Special Note: From here. “During the remainder of the year a larger SST anomaly, up to +1.5°C in November-December-January, is required in order to reach the threshold to support persistent deep convection in that region.” The latest reading I have seen with respect to the ONI was 0.6 and most models predict values of around 0.8 for this winter and spring. So it is not clear the extent to which this El Nino will produce the convective response of the typical El Nino or other weather impacts of a typical El Nino

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THE MJO HAS REMAINED ACTIVE OVER THE PAST TWO WEEKS, AND IS FORECAST TO PROPAGATE INTO THE PACIFIC OVER THE NEXT WEEK TO 10 DAYS. THIS FAVORS A COLDER SOLUTION RELATIVE TO NORMAL ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS FOR THE LAST 10 TO 15 DAYS OF THE MONTH.

COMBINING THE ABOVE FACTORS WITH UNANIMOUS MODEL AGREEMENT AMONG THE EXTENDED RANGE ECMWF, CFS, AND JMA, A WARMER-THAN-NORMAL DECEMBER FOR MUCH OF THE CONUS AND ALASKA IS FAVORED. SOME BELOW-NORMAL TEMPERATURES ARE FAVORED ALONG THE GULF COAST WHERE A +PNA HAS A STRONG TEMPERATURE FOOTPRINT, AND WHERE ANY PATTERN CHANGE LATE IN THE MONTH WOULD CONTRIBUTE TO BELOW-NORMAL TEMPERATURES. PROBABILITIES ARE GENERALLY LOW, HOWEVER, REFLECTING THE MIDDLE AND LATE MONTH UNCERTAINTY, GIVEN THE MJO SIGNAL FOR A PATTERN CHANGE.

THE PRECIPITATION OUTLOOK IS CHANGED TO REFLECT THE CHANGES IN MODEL GUIDANCE  FROM THE ECMWF, CFS, AND JMA, AS WELL AS TO HARVEST THE HIGH CONFIDENCE SHORT-RANGE FORECASTS FOR THE NEXT SEVERAL DAYS. COMBINING THESE FACTORS WITH THE WEEK-2 OUTLOOK INFORMS THE PRECIPITATION OUTLOOK FOR THE MONTH. EQUAL CHANCES ARE INDICATED OVER MUCH OF THE EASTERN CONUS, WHERE PRECIPITATION SIGNALS ARE WEAK EARLY IN THE MONTH. IN THE SOUTHEAST, THOUGH BELOW-MEDIAN PRECIPITATION IS FAVORED FOR THE FIRST 10 DAYS OF THE MONTH, THE MJO AND ANY LOW-FREQUENCY ENSO SIGNAL FAVOR NEAR- TO ABOVE-MEDIAN PRECIPITATION LATER IN THE MONTH.”

Three-Month Outlook – Important because it is the heart of the Winter Season

Here is the recently issued (November 20) Temperature Outlook for the months of December 2014 through February 2015.

One can see how the December Outlook fits into this picture.

Here is the Precipitation Outlook for Dec – Feb which was issued on November 20.

One can see how the updated December Precipitation Outlook fits into this picture.

All in all, the picture is becoming more coherent and less chaotic. But I do not have a lot of faith in it as it depends on an El Nino of questionable strength this winter.

Short-term Outlook

Now let us take a look at the 8 – 14 day outlook that was issued today November 24, 2014.

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.

Here is the 8 – 14 Day Temperature Outlook released today (but it will auto-update every day so it will be changing day by day so my comments may become out of sync with the map):

Since today is December 1 and the Updated December Outlook was issued yesterday, it is not surprising that this 8 – 14 Day Outlook seems to fit within the Month Outlook given that it just covers seven days. The “First Week” map which can be found in Part 2 of this Report is fairly similar.

And here is the 8 – 14 Day Precipitation Outlook issued today (but it will auto-update and change every day so my comments may become out of sync with the map).

This map looks a lot like the maps issued over the weekend as it shows a lot of detail that the meteorologists often smooth out. But presumably the support for this level of variation is strong. The “First Week” map which can be found in Part 2 of my Report is very similar. In both cases the well advertised Pacific Coast Storm from the extended trough has been downgraded.

And excerpts from the NOAA discussion.

“6-10 DAY OUTLOOK FOR DEC 07 – 11 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 BROAD TROUGH OVER THE NORTH PACIFIC  OCEAN.  A SPLIT FLOW IS FORECAST OVER WESTERN NORTH AMERICA, WITH A TROUGH IN  THE SOUTHERN STREAM OVER THE SOUTHWEST AND A RIDGE DIRECTLY NORTH OF IT OVER  WESTERN NORTH AMERICA. TODAY’S MANUAL BLEND CHART INDICATES ABOVE NORMAL  HEIGHTS FOR MOST OF THE CONUS EXCEPT FOR THE GULF COAST STATES. THE ENSEMBLE  SPAGHETTI DIAGRAMS INDICATE LOW SPREAD ACROSS THE MAJORITY OF THE FORECAST  DOMAIN. MORE WEIGHTING WAS GIVEN TO THE EUROPEAN ENSEMBLE MEAN BASED ON ITS  SKILL DURING THE PAST 60 DAYS AS ASSESSED BY 500-HPA HEIGHT ANOMALY  CORRELATIONS.

ABOVE-NORMAL 500-HPA HEIGHTS ARE FORECAST OVER MUCH OF THE COUNTRY LEADING TO  ENHANCED CHANCES OF ABOVE-NORMAL FOR MOST OF THE CONUS EXCEPT FOR FLORIDA WHERE NEAR-NORMAL TEMPERATURES ARE  FORECAST. A RIDGE EXTENDS FROM THE WEST COAST OF CANADA INTO EASTERN ALASKA,  INCREASING CHANCES FOR ABOVE-NORMAL TEMPERATURES IN THE EASTERN PART OF THE  STATE, WHILE NEAR-NORMAL TEMPERATURES ARE FAVORED FOR WESTERN ALASKA.

TROUGHING OVER THE NORTH PACIFIC OCEAN WITH AN ENHANCED PACIFIC JET FAVORS ABOVE-MEDIAN PRECIPITATION FROM THE PACIFIC NORTHWEST TO THE NORTHERN GREAT  BASIN. THE CHANCES FOR NEAR TO ABOVE-MEDIAN PRECIPITATION AMOUNTS ARE ELEVATED  FOR PARTS OF THE SOUTHERN PLAINS AND THE SOUTHEASTERN CONUS NEAR AND AHEAD OF  THE ANTICIPATED SOUTHERN STREAM TROUGH. THE PREDICTION OF A DEVELOPING RIDGE  UPSTREAM OVER WESTERN CANADA ENHANCES CHANCES OF BELOW-MEDIAN PRECIPITATION  AMOUNTS FOR THE NORTHERN ROCKIES, NORTHERN GREAT PLAINS AND UPPER MISSISSIPPI  VALLEY. BELOW-MEDIAN PRECIPITATION IS FAVORED OVER WESTERN ALASKA, CONSISTENT  WITH NAEFS AND GEFS REFORECAST GUIDANCE.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: NEAR AVERAGE, 3 OUT OF 5, DUE TO  DUE TO FAIRLY GOOD AGREEMENT IN THE DETAILS BETWEEN THE VARIOUS ENSEMBLE MEANS  AND DETERMINISTIC SOLUTIONS.

8-14 DAY OUTLOOK FOR DEC 09 – 15 2014

THE ENSEMBLE MEAN PREDICTIONS OF THE 500-HPA HEIGHTS FOR THE WEEK-2 PERIOD ARE IN FAIRLY GOOD AGREEMENT OVER NORTH AMERICA. A BROAD TROUGH IS FORECAST OVER  THE NORTH PACIFIC OCEAN. MOST MODEL SOLUTIONS PREDICT A SPLIT FLOW OVER WESTERN  NORTH AMERICA, WITH A TROUGH IN THE SOUTHERN STREAM OVER THE SOUTHWEST AND A  RIDGE DIRECTLY NORTH OF IT OVER WESTERN NORTH AMERICA. 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.

ABOVE-NORMAL 500-HPA HEIGHTS ARE FORECAST OVER MUCH OF THE COUNTRY LEADING TO ENHANCED CHANCES OF ABOVE-NORMAL TEMPERATURES FOR MOST OF THE CONUS EXCEPT FOR THE GULF COAST STATES WHERE NEAR-NORMAL TEMPERATURES ARE FORECAST. INCREASING  CHANCES FOR ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR SOUTHERN ALASKA, WHILE  NEAR-NORMAL TEMPERATURES ARE FAVORED FOR NORTHERN ALASKA.

TROUGHING OVER THE NORTH PACIFIC OCEAN WITH AN ENHANCED PACIFIC JET FAVORS ABOVE-MEDIAN PRECIPITATION FROM THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA  TO THE NORTHERN GREAT BASIN. THE CHANCES FOR NEAR TO ABOVE-MEDIAN PRECIPITATION  AMOUNTS ARE ELEVATED FOR PARTS OF THE SOUTHERN PLAINS AND THE EASTERN CONUS  NEAR AND AHEAD OF THE ANTICIPATED SOUTHERN STREAM TROUGH. ANOMALOUS SOUTHERLY  FLOW INCREASES CHANCES FOR ABOVE-MEDIAN PRECIPITATION ACROSS SOUTHEASTERN  ALASKA AND THE ALASKAN PANHANDLE. BELOW-MEDIAN PRECIPITATION IS FORECAST OVER  THE SOUTHWEST AND WESTERN ALASKA, CONSISTENT WITH NAEFS AND GEFS REFORECAST GUIDANCE.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: NEAR AVERAGE, 3 OUT OF 5, DUE TO DUE TO FAIRLY GOOD AGREEMENT IN THE DETAILS BETWEEN THE VARIOUS ENSEMBLE  MEANS AND DETERMINISTIC SOLUTIONS.”

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?

The analogs are a mixed bag with the unifying factor being a negative AMO. The analogs no longer show a positive PDO. Of most interest is the 1982 El Nino which arrived late and weak but evolved into a very strong El Nino.

Sometimes it is useful to take a look at the location of the Jet Stream or Jet Streams.

And sometimes the forecast is revealing. This is the forecast out five days.

To see it in animation, click here. At the time this article was published the animation shows a tendency for there to be a Southern Branch of the Polar Jet Stream in addition to the usual Northern Branch. It can bring storms further south than usual.

This is consistent with an El Nino.

El Nino Discussion

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 has been some warm surface water. Also you see more pockets of warmer water further east. Overall it does seem to be becoming more widespread but somewhat less so close to Ecuador and a bit more so in the Central Pacific where the ONI Index is measured. 

You can see why the official ENSO indicators are flashing El Nino “conditions” because the warm water is where those readings are taken.

Of most interest to NOAA is 120 W to 170 W as that is where the ONI Index is measured. More information can be found here. If you look at the color coding in the above Hovmoller they are looking for shades where the redder the better re conditions being El Nino but so far it is just showing shades of tan and brown i.e. marginal especially when averaged over the entire area of interest. But that explains why we have a situation where some of the factors are in place for an El Nino but so far it is marginal at best.

And now the low-level wind anomalies.

If anything, this looks far less impressive than last week which you can tell by looking at the bottom of the chart. The bottom shows the most recent readings as this type of graphic is read from top to bottom. The “reddish” area is much reduced and there is more “blue” over towards Ecuador.

The Southern Oscillation Index (SOI) is cooperating this week 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. The 30 day average is now marginal for El Nino conditions but improved since last week. Today’s reading is -17.2.

You can not deduce anything from one day but it reminds us that situations can change rapidly. Given that -8.0 is often considered the threshold for El Nino conditions you can see that August and October were actually more favorable for the development of an El Nino than November. The 30 (important) and 90 day averages of the SOI are now marginal for what is associated with an El Nino but certainly not anything to get excited about.

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 but it does seem to be more potent than the immediately prior Kelvin wave. 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 expect 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. At this point there is no sign of an upwelling wave. That is why I believe this El Nino will arrive weak, possibly then get weaker (just extrapolating from this Hovmoller as to where the warm water will be in a month), but could later be reinforced by another Kelvin Wave and last longer than currently forecast. 

So this continues to look to me 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. This may not happen right away as so far this looks like a traditional El Nino but it may turn out to be a two-year event.

I still do not see a traditional El Nino of any significant strength likely to happen this winter, especially in the early part of winter, although a weak El Nino appears to be making its presence known. 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 short weak traditional El Nino which arrives late and then weakens (see graphic below)
  
• 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 but not likely to be strong this year.
  
• A weak traditional El Nino that turns into a Modoki next year (The Japanese Forecast)
• 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.

One more graphic:

I have a version of this graphic on Page 2 of my Report but this is a “corrected version” which is issued each Monday with the NOAA ENSO Report. I am not sure what the corrections are but I am guessing they are the same as the corrections made to the maps on the right. Those maps may be difficult to read in this graphic but larger versions can be found here. The maps found at that link can be clicked on and enlarged. Back to the spaghetti chart, notice the ONI declines from where it is today through Jan-Feb-March (as suggested by the Kelvin Wave Hovmoller that I presented earlier) almost to ENSO Neutral and then increases going into the summer. I am familiar with the Spring Prediction Barrier but nevertheless since this is one of the main tools used by NOAA, their forecast remains somewhat of a mystery.

Impacts of Climate Change

From the Russian News Agency Tass this short assessment. Basically they like the idea of being warmer.

Click Here for the Econointersect Weather and Climate Page where you will find:

• 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. This section of the report has been reorganized to make it easier to follow.
  
• 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. I have included a Table of Contents but so far have not implemented hyperlinks to move quickly to topics of most interest. For now you have to scroll down.