Written by Sig Silber
. . . but wetter weather is anticipated expanding from west to east. NOAA has also toned down their temperature forecast a bit. It is pretty much late Summer early Fall weather but a lot of uncertainty related to the timing of the pattern i.e. how rapidly certain features within the pattern will move from west to east. There will be an update of the seasonal forecast on Thursday which I will report on next Monday as I do not anticipate that it will be shocker. Not much sign of the El Nino yet. It is very strong and appears to have peaked with respect to how it is measured. The question that remains is will the impacts match the ONI readings and where.
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.
This week I will immediately focus on the Current (Right Now to 5 Days Out) Weather Situation. There will be a new Climate Update Issued later this week.
A more complete version of this report with daily forecasts is available in Part II. This is a summary of that more extensive report. This link Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks will take you directly to that set of information but in some Internet Browsers it may just take you to the top of Page II where there is a TABLE OF CONTENTS and you may have to wait for a few seconds for your Browser to redirect to the selected section with that Page or if that process is very slow you can simply click a second time within the TABLE OF CONTENTS to get to that specific part of the webpage.
First, here is a national animation of weather front and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at the link provided above.
The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic; because they are implemented by color coding.
The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients. When I looked at this graphic yesterday, I could clearly see the trough coming down from the Great Lakes and the ridge over the Rocky Mountains. But what a difference a day makes and today the forecast is quite different with a trough in the West being the only dominant feature impacting CONUS on Day 7.
Because “Thickness Lines” are shown by those green lines on this graphic it is a good place to define “Thickness” and its uses. You can find a full uk.sci.weather style explanation (thorough) at that link or just remember that Thickness measures the virtual temperature plus moisture content) of the lower atmosphere and is very useful especially in the winter at identifying areas prone to snow and in the summer areas which are going to be hot and humid. Here is a U.S. style explanation of “Thickness” by Jeff Haby who is a valuable source of Haby Hints for anyone who wants an explanation of a meteorological term. The thickness lines do not yet indicate winter conditions which might be thickness levels below 540 for most areas. The above uk.sci.weather link is is an explanation for the U.K. The levels for CONUS might be slightly different. Obviously these thickness lines do not tell you about mountain peaks. The particular definition of “thickness” on this graphic may not be the best way to define the snow line and this is discussed in the link provided but it is I believe the older method and gives a first approximation which can be further refined as per the discussion in the link. This graphic indicates normal west to east movement of air masses for the most part except along the coasts.
On Sunday, thickness lines 582 and 576 dominated the entire southern half of CONUS. Today the forecast is different for the west but the 582 and 576 thickness lines are still a major feature for the eastern half of CONUS although I anticipate that NOAA may downplay them tomorrow: just a hunch. Thickness lines 582 and 576 are more usually associated with Summer rather than Fall conditions. The following table is useful but designed for Europe. I was not able to find the corresponding information for the U.S. but it would not be drastically different. In the U.S., the last zero is dropped off the Thickness Level so where it says 5640 that would show as 564 in the U.S. Also remember the temperatures shown are in Centigrade. So 580 would correspond to about 80F in full sunshine during the summer. That is why I say the 582 and 576 thickness levels are a bit unusual for mid to late October.
More information on this table is available here.
The level of storm activity in the Western Pacific has tapered off quite a bit. Well maybe not so much right now. Notice the Northern Pacific is like a giant anticyclone with clockwise motion so that which gets sent west due to El Nino is to some extent returned to North America but at higher latitudes.
At this time of the year, warm water off of the coast of Mexico, such as from an El Nino or a positive PDO reduces the ocean/land temperature differential and can weaken the Monsoon overall (and it is essentially over for this year) but the cyclones generated by that warm ocean water can enhance the Monsoon or provide Monsoon-like impacts for short periods if those cyclones stay close enough to the Mexican coastline. So that is what is being watched now and there seems to be an endless sequence of the storms forming. Each of these El Nino related tropical storms off the coast of Mexico has the potential, if they are close enough to shore, to introduce moisture into the circulation that enters CONUS and that has been the case this summer but it is sporadic. It also mostly benefited the western side of Mexico and the western reach in CONUS of the Southwest Monsoon but there has been a tendency for some of that moisture to also benefit New Mexico. But overall it has diminished the impact of the Southwest Monsoon as it has cut off any Gulf of Mexico involvement and generally has impacted a smaller number of states than is usually the case. For Mexico, an El Nino is a drought event. There is yet another storm moving up the West Coast of Mexico. It is not yet clear if that storm will have a big impact on CONUS. It is a dynamic situation with a strong El Nino.
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The graphic below is harder to look at but provides more detail on the water vapor being generated by these storms and the normal summer action of the Southwest Monsoon. It covers a much larger area within CONUS so you can see where the moisture currently is and is going. This graphic is very good at pointing out the divisions between cloudy and not cloudy areas.
As I am looking at this graphic Monday evening, I see mostly a dearth of water vapor over CONUS except the storm above the Great Lakes. This is also a pretty good moisture tap into the Southwest which is a combination of moisture from multiple sources including a low-pressure system off the West Coast, the remains of a tropical cyclone, and the loop de loop storm that was a remnant of an earlier tropical cyclone that crossed part of the southwest and then retrograded though Mexico and is now returning. All of these sources have merged. Right now we have mostly Chamber of Commerce weather almost everywhere.
Here is a broader view of projected tropical hazards and benefits over an approximately two-week period. There are two views. One is more focused on the Pacific and one that includes the Indian Ocean and covers Asia more completely. Both graphics auto-update weekly but each updates on a different day of the week so when you look at them both carefully you might see some differences due to the exact day when they were updated. More information can be found here. The discussion at that link may update on Tuesdays. I am not sure.
Looking at the first graphic (and as I am looking at it, it is the most recently updated) what stands out to me, at the time of publication, is the precipitable water in place in the Southeast of CONUS. Last week that Pacific Tropical moisture that migrated across Central America to the Southeast got tangled up with East Coast tropical activity producing extreme flooding. Weather forecasters perhaps should have noticed that situation developing and suggested an evacuation. This week we do not see that potential for cyclonic activity shown for the Southeast. It is shown for the West Coast of Mexico with high rainfall potential north of the area where the cyclonic activity might develop.
This graphic below covers a larger part of the world. With this graphic, at the time of publication, you see more activity over by Asia including dry conditions in Indonesia and the Philippines as well as some wetter than usual conditions in the Indochina area. There is also the potential for tropical storm activity east and north of Indonesia. At the time of publication, the above graphic was more current for North and South America but the below graphic might be updated by the time you read this report. It gets confusing and I realize that, but the two graphics update on different days. I think the bottom graphic updates on Tuesdays and the top graphic on Fridays.
Below is a view which highlights the surface Highs and the Lows re air pressure on Day 6 (Day 3 can be seen in Part II of this Report). Over the past week or so the projected location and strength of the Aleutian Low has varied a bit. On some days the forecast is showing a split low with each of the two lows weaker than a combined single Low and this is not characteristic of El Nino. We will have to monitor that. A longer discussion of the climate of Beringia is in Part II of this Report 2. Medium Frequency Cycles such as ENSO and IOD. The atmospheric pressure systems off the West Coast are complicated and appear in some cases to be forcing the tropical storms moving up the coast off of Mexico inland. The RRR is not present or at least not prominent which is a change from the situation the last three or four years. Oops, it is there in today’s version of this graphic which is not good news for California. This past week the Aleutian Low actually allowed a Hurricane to move up the coast off of Oregon and Washington States. A prominent feature shown in yesterdays version of this graphic was the Low Pressure forecast for Hudson’s Bay which would have impacted the Great Lakes Region of CONUS. But that is not in the forecast now except in the Jet Stream forecast which has yet to get with the program. Looks like the Low over Hudson’s bay is now expected to move to the east rapidly.
We now need to monitor the Jet Stream to see if it is shifting to the South. This is the forecast out five days.
To see how the pattern is projected to evolve, please click here. The activity still appears to be mostly north rather than south but with a dip near the Great Lakes. We have not yet seen the pattern changing to a consistent presence of a southern branch of the Jet Stream which we would expect with El Nino.
And when we look at Sea Surface anomalies we see a lot of them not just along the Equator related to El Nino. But the extent of the warm water off the West Coast appears to be a bit less than recently. The Atlantic has really heated up. You can tell a lot from this graphic. The warm anomalies are not evenly distributed around the world. There is more in the Northern Hemisphere possibly related to there being more land in the Northern Hemisphere. So there may be a connection to the ratio of land to water and the heating of the water surface. The warm water off of California is a wild card in the impacts of this El Nino.
The two graphics below show first the changes over the four weeks (ending September 16) as compared to the above graphic which shows the current SST anomalies and then the changes over the four weeks ending on October 7. Looking at both of these change in anomaly graphics is helpful in putting the current situation shown above into perspective.
First the four weeks ending on September 16.
Now the four weeks ending on October 7.
In both graphics you can see the increasing change of the warm anomaly in the Nino Area but lately mostly very close to Ecuador. Further south we now see waters off the west coast of South America getting cooler. Of note the warming of the part of the Atlantic where hurricanes develop has continued off the coast of West Africa but has gotten less intense (but if you look at the daily readings still a warm anomaly) closer to the Caribbean and the U.S. Southeast. We are now somewhat less likely to see a repeat of that terrible storm that hit the U.S. Southeast and the Bahamas. Also the warm water off the west coast of Australia is less evident and not able to fully cancel out the IOD. The water west of the U.S. has gotten warmer right off California and further south along the west coast of Central America which explains the succession of tropical storms there. The waters off of Europe seem to be a bit warmer (or less cold as that is two ways of saying the same thing). You can see the impact of El Nino on Indonesia.
Remember these are four-week averages and graphic above the two four-week average of the changes in the anomalies is the daily readings of the anomalies which auto-updates. You can get a better feel there for the current impacts. It is difficult to relate the actuals to the four-week changes but it paints a picture. Remember the observed values in the first graphic are expressed as anomalies which is the change from climatology (normal) so we are talking in these two bottom two graphics about the change in the change. It is kind of like the first derivative of the “anomalies” which to confuse things NOAA interchanges the word “anomaly” and “departures” which are the same thing.
6 – 14 Day Outlooks
Now let us focus on the 6 – 14 Day Forecast for which I generally only show the 8 – 14 Day Maps. The 6 – 10 Day maps are available in Part II of this report.
To put the forecasts which NOAA tends to call Outlooks into perspective, I am going to show the three-month OND and single month of October forecasts and then discuss the 8 – 14 day Maps and the 6 – 14 Day NOAA Discussion within that framework.
First Temperature
Here is the Three-Month Temperature Outlook issued on September 17, 2015:
And here is the Updated October Temperature Outlook issued on September 30, 2015.
Below is the current 8 – 14 Day Temperature Outlook Map which will auto-update and thus be current when you view it. It covers the week following the current week. Today’s 6 – 14 Day Outlook is just nine days of the month and the map shown below of the 8 to 14 day Outlook only shows seven days. The 6 – 10 Day Map is available on Page II of this report. As I view this map on October 12 (it updates each day) it appears that the second half of October will continue to defy Fall but not to the extend the unsupervised computers thought yesterday. It is still fairly impressive as compared to the monthly outlook.
Now Precipitation
Here is the three-month Precipitation Outlook which was issued on September 17, 2015:
And here is the Updated October Precipitation Outlook Update Issued on September 30, 2015.
Below is the current 8 – 14 Day Precipitation Outlook Map which will auto-update and thus be current when you view it. It covers the week following the current week. Today’s 6 – 14 Day Outlook is just nine days of the month and the map shown covers seven days of the nine. The 6 – 10 Day Map (the two maps overlap) is available on Page II of this report. As I view this map on October 12 (it updates each day) it appears that CONUS is certainly wetter to the west and drier to the east. Oops. That was the interpretation of the maps issued by the unsupervised computers yesterday. Today the pattern has shifted to the east perhaps more than one might expect with the passage of just 24 hours and CONUS other than Northern California is wet. It is a little hard to imagine how the pattern shown can actually come about but that is the forecast.
Here are excerpts from the NOAA discussion released today October 12, 2015. It covers the full nine day period not just the seven days shown in the 8-14 Day Map.
6-10 DAY OUTLOOK FOR OCT 18 – 22 2015
TODAY’S GFS AND ECMWF ENSEMBLE MEANS, AS WELL AS THE DETERMINISTIC GFS SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE EXPECTED LARGE SCALE 500-HPA CIRCULATION PATTERN OVER NORTH AMERICA. TROUGHS ARE PREDICTED BY THESE SOLUTIONS OVER THE ALEUTIANS, THE WESTERN CONUS, AND THE CANADIAN MARITIMES. RIDGES ARE FORECAST OVER MAINLAND ALASKA AS WELL AS PARTS OF THE SOUTHEASTERN CONUS. HOWEVER, THERE ARE NOTICEABLE DIFFERENCES AMONG MODEL SOLUTIONS ON THE DETAILS OF THE EXPECTED PATTERN, PARTICULARLY OVER THE WESTERN CONUS. WHILE THE GFS-BASED SOLUTIONS AND ECMWF ENSEMBLE MEAN PREDICT CYCLONIC FLOW OVER MOST OF THE WESTERN CONUS, THE 0Z CANADIAN ENSEMBLE MEAN FORECASTS SPLIT FLOW ACROSS THIS REGION WITH ZONAL FLOW ACROSS THE NORTHERN TIER AND A TROUGH OVER THE SOUTHWEST CONUS. THE DETERMINISTIC 0Z ECMWF ALSO PREDICTS SPLIT FLOW OVER THE WESTERN CONUS AND FORECASTS A SEPARATE TROUGH IN THE NORTHERN STREAM OVER THE NORTHERN HIGH PLAINS. DUE TO THESE UNCERTAINTIES, TODAY’S OFFICIAL 500-HPA MANUAL BLEND IS COMPOSED PRIMARILY OF THE ENSEMBLE MEAN SOLUTIONS. THE GREATEST WEIGHTS WERE GIVEN TO TODAY’S GFS AND ECMWF ENSEMBLE MEANS DUE PRIMARILY TO CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERNS MATCH CASES THAT HAVE OCCURRED IN THE PAST.
GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE ECMWF FAVOR ABOVE NORMAL TEMPERATURES FOR MOST OF THE WESTERN CONUS. HOWEVER, ABOVE NORMAL TEMPERATURE PROBABILITIES WERE REDUCED RELATIVE TO YESTERDAY’S OFFICIAL OUTLOOK DUE TO A TROUGH PREDICTED OVER THE WESTERN CONUS IN TODAY’S OFFICIAL 500-HPA HEIGHT BLEND AND UNCERTAINTIES SURROUNDING THE POTENTIAL FAST PROGRESSION OF SHORTWAVE FEATURES DURING THIS TIME PERIOD. BELOW NORMAL TEMPERATURES ARE EXPECTED EARLY IN THE PERIOD OVER MUCH OF THE NORTHEAST CONUS AND MID ATLANTIC BEHIND A TROUGH FORECAST OVER EASTERN CANADA. ABOVE NORMAL TEMPERATURES ARE LIKELY OVER ALASKA DUE TO PREDICTED RIDGING AND ABOVE NORMAL HEIGHTS. FORECAST TOOLS ALSO SUPPORT ABOVE NORMAL TEMPERATURES FOR FLORIDA. HOWEVER, ENHANCED ABOVE NORMAL TEMPERATURE PROBABILITIES WERE KEPT LOW DUE TO A POTENTIAL FRONTAL PASSAGE NEAR THE BEGINNING OF THE OUTLOOK PERIOD.
ABOVE MEDIAN PRECIPITATION IS FAVORED OVER MUCH OF THE WESTERN AND CENTRAL CONUS IN ASSOCIATION WITH FORECAST MEAN CYCLONIC FLOW OVER THE REGION. BELOW MEDIAN PRECIPITATION IS FAVORED FOR PARTS OF THE EASTERN CONUS BEHIND A TROUGH FORECAST OVER EASTERN CANADA. AN EXCEPTION IS FLORIDA, WHERE PREDICTED MEAN EASTERLY SURFACE FLOW LEADS IN ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE PENINSULA. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR SOUTHEASTERN ALASKA, AHEAD OF A TROUGH PREDICTED OVER THE ALEUTIANS.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO UNCERTAINTIES SURROUNDING THE POTENTIAL FAST PROGRESSION OF SHORTWAVE FEATURES ACROSS MUCH OF THE FORECAST DOMAIN.
8-14 DAY OUTLOOK FOR OCT 20 – 26 2015
DURING THE WEEK TWO PERIOD, TODAY’S GFS-BASED SOLUTIONS AND ECMWF ENSEMBLE MEAN FORECAST A TROUGH OVER THE BERING SEA AND BROAD, CYCLONIC FLOW OVER MUCH OF THE CONUS. THE GFS-BASED SOLUTIONS PREDICT A MEAN TROUGH TO BE CENTERED OVER THE INTERIOR WEST WHILE TODAY’S 0Z ECMWF ENSEMBLE MEAN HAS THIS TROUGH CENTERED OVER THE CENTRAL CONUS. THE 0Z CANADIAN ENSEMBLE MEAN PREDICTS MOSTLY ZONAL FLOW ACROSS MUCH OF THE CONUS. ENSEMBLE SPREAD IS MODERATELY HIGH FOR MUCH OF THE FORECAST DOMAIN INDICATING THAT MODELS ARE HAVING DIFFICULTY RESOLVING THE PROGRESSION OF INDIVIDUAL SHORTWAVE FEATURES DURING THIS TIME PERIOD. DUE TO THIS UNCERTAINTY, TODAY’S WEEK TWO MANUAL 500-HPA HEIGHT BLEND IS BASED PRIMARILY ON THE ENSEMBLE MEAN SOLUTIONS. THE GREATEST WEIGHTS WERE GIVEN TO THE GFS AND ECMWF ENSEMBLE MEANS DUE TO CONSIDERATIONS OF RECENT SKILL AND ON ANALOG CORRELATIONS.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MOST OF ALASKA AHEAD OF A TROUGH PREDICTED OVER THE ALEUTIANS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE EASTERN CONUS AHEAD OF A TROUGH PREDICTED OVER THE WEST CENTRAL CONUS. GEFS REFORECAST GUIDANCE AND BIAS CORRECTED TEMPERATURES FROM THE 0Z ECMWF ENSEMBLES ALSO FAVOR ABOVE NORMAL TEMPERATURES FOR MOST OF THE WESTERN CONUS. HOWEVER, AS WAS THE CASE IN THE 6 TO 10 DAY PERIOD, ENHANCED ABOVE NORMAL TEMPERATURE PROBABILITIES WERE REDUCED SIGNIFICANTLY RELATIVE TO YESTERDAY’S OFFICIAL OUTLOOK DUE TO A POTENTIAL MEAN TROUGH AFFECTING THE WESTERN CONUS DURING THE WEEK TWO PERIOD.
ABOVE MEDIAN PRECIPITATION IS FAVORED FOR THE CENTRAL CONUS AHEAD OF A MEAN TROUGH FORECAST OVER THE INTERIOR WEST. THERE ARE ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR MUCH OF SOUTHERN ALASKA AHEAD OF A TROUGH PREDICTED OVER THE ALEUTIANS. NEAR TO BELOW MEDIAN PRECIPITATION IS FAVORED FOR NORTHERN ALASKA DUE TO PREDICTED RIDGING. ENHANCED PROBABILITIES OF BELOW MEDIAN PRECIPITATION ARE INDICATED FOR PARTS OF CALIFORNIA DUE TO A RIDGE PREDICTED OFF THE COAST. CONVERSELY, ABOVE MEDIAN PRECIPITATION IS FAVORED FOR FLORIDA IN ASSOCIATION WITH PREDICTED MEAN EASTERLY SURFACE FLOW.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE TO MODERATE TO HIGH MODEL SPREAD OVER MUCH OF THE FORECAST DOMAIN.
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.
Analog Centered Day | ENSO Phase | PDO | AMO | Other Comments |
1952 Sept 26 | Neutral | – | + | |
1952 Sept 27 | Neutral | – | + | |
1960 Oct 22 | Neutral | – | + | |
1960 Oct 24 | Neutral | – | + | |
1965 Oct 1 | El Nino | – | – | Fairly Strong |
1980 Sept 27 | Neutral | + | – | |
1980 Sept 28 | Neutral | + | – | |
1984 Oct 4 | La Nina | + | – |
It is amazing that there is only one El Nino analog. That is fairly convincing that our near-term weather is not going to be very influenced by El Nino. The phases of the ocean cycles were most consistent with McCabe Conditions A and D which are pretty much opposites of each other. Both the Atlantic and the Pacific are in control. The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. My take away from this and other information presented in this report is that the PDO has not changed phase and the current PDO plus is related to the current El Nino and the prior near El Nino. It most likely will return to PDO – or PDO neutral next winter and seems to be doing that gradually now. Water Planners might usefully pay attention to the low-frequency cycles such as the AMO and the PDO as the media tends to focus on the current and short-term forecasts to the exclusion of what we can reasonably anticipate over multi-decadal periods of time.
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.
Historical Anomaly Analysis
When I see the same dates showing up often I find it interesting to consult this list.
With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not significant. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.
El Ninos | La Ninas | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Start | Finish | Max ONI | PDO | AMO | Start | Finish | Max ONI | PDO | AMO | |
DJF 1950 | J FM 1951 | -1.4 | – | N | ||||||
T | JJA 1951 | DJF 1952 | 0.9 | – | + | |||||
DJF 1953 | DJF 1954 | 0.8 | – | + | AMJ 1954 | AMJ 1956 | -1.6 | – | + | |
M | MAM 1957 | JJA 1958 | 1.7 | + | + | |||||
M | SON 1958 | JFM 1959 | 0.6 | + | – | |||||
M | JJA 1963 | JFM 1964 | 1.2 | – | – | AMJ 1964 | DJF 1965 | -0.8 | – | – |
M | MJJ 1965 | MAM 1966 | 1.8 | – | – | NDJ 1967 | MAM 1968 | -0.8 | – | – |
M | OND 1968 | MJJ 1969 | 1.0 | – | – | |||||
T | JAS 1969 | DJF 1970 | 0.8 | N | – | JJA 1970 | DJF 1972 | -1.3 | – | – |
T | AMJ 1972 | FMA 1973 | 2.0 | – | – | MJJ 1973 | JJA 1974 | -1.9 | – | – |
SON 1974 | FMA 1976 | -1.6 | – | – | ||||||
T | ASO 1976 | JFM 1977 | 0.8 | + | – | |||||
M | ASO 1977 | DJF 1978 | 0.8 | N | – | |||||
M | SON 1979 | JFM 1980 | 0.6 | + | – | |||||
T | MAM 1982 | MJJ 1983 | 2.1 | + | – | SON 1984 | MJJ 1985 | -1.1 | + | – |
M | ASO 1986 | JFM 1988 | 1.6 | + | – | AMJ 1988 | AMJ 1989 | -1.8 | – | – |
M | MJJ 1991 | JJA 1992 | 1.6 | + | – | |||||
M | SON 1994 | FMA 1995 | 1.0 | – | – | JAS 1995 | FMA 1996 | -1.0 | + | + |
T | AMJ 1997 | AMJ 1998 | 2.3 | + | + | JJA 1998 | FMA 2001 | -1.6 | – | + |
M | MJJ 2002 | JFM 2003 | 1.3 | + | N | |||||
M | JJA 2004 | MAM 2005 | 0.7 | + | + | |||||
M | ASO 2006 | DJF 2007 | 1.0 | – | – | JAS 2007 | MJJ 2008 | -1.4 | – | + |
M | JJA 2009 | MAM 2010 | 1.3 | – | + | JJA 2010 | MAM 2011 | -1.4 | + | + |
JAS 2011 | FMA 2012 | -0.9 | – | + | ||||||
T | MAM 2015 | NA | 1.0 | + | N |
Progress of the Warm Event
Let us start with the SOI.
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 moving/running average and the third is the 90 day moving/running average.
Date | Current Reading | 30-Day Average | 90 Day Average |
6 Oct | -20.2 | -22.37 | -17.97 |
7 Oct | -14.8 | -22.43 | -18.17 |
8 Oct | -16.4 | -22.59 | -18.32 |
9 Oct | -23.1 | -22.72 | -18.57 |
10 Oct | -24.3 | -22.52 | -18.80 |
11 Oct | -18.6 | -22.02 | -18.90 |
12 Oct | -22.8 | -21.91 | -18.95 |
The 30-day average, which is the most widely used measure, on October 12 was reported as being -21.91 which is a very high (negative) level and is clearly a reading associated with an El Nino and insignificantly lower than last week. The 90-day average also is solidly in El Nino territory at -18.95 which is lower (stronger) than last week. The SOI is clearly indicative of an El Nino Event in progress. In fact it is so strong that it may be having impacts that are unusual. This past week where were not the really extreme values we have seen in prior weeks just high values. This can be important as some studies show that the change in the level of SOI is at least as important as the actual level in terms of predicting precipitation.
Low-Level Wind Anomalies
Here are the low-level wind anomalies. The area from 180W to 160W is now of interest. Will it initiate yet another Kelvin Wave? NOAA says it has.
In the below graphic, you can see how the convection pattern (really cloud tops has since May shifted to the East from a Date Line (180) Modoki pattern to a 170W to 120W Traditional/Canonical El Nino Pattern. But recently the signs of an El Nino are getting quite faint and shifting back to the west. You can see the lack of convection over at 120W which is Indonesia but the convection has withdrawn to the West not moved to the East as would be the case with a normal El Nino. That may still happen. In the 1997/1998 El Nino, that did not happen until 1998 which is why the Fall of 1997 was not wet for CONUS.
When I hear that with this El Nino the atmosphere is strongly coupled with the ocean, I really wonder what those meteorological agencies are smoking. For sure the SOI is behaving like it would be expected to behave in a strong El Nino. The Easterlies in the Pacific along the Equator are suppressed. So if this is all that is meant, that part has fallen into place. But the Walker Circulation may not be consistent with a standard El Nino. That is my point.
The interconnection with the Indian Ocean seems to be unusual to say the least. The convection in the Pacific along the Equator has not moved east. It has moved away from Indonesia which is an El Nino impact but it is remaining where one would expect it to be if this was a Modoki. This graphic may start to change soon. But it may not be in the direction of more convection further east. The October 5 Update, which is what I am looking at on Monday October 12, suggests that the area of anomalies in convection is strongest over by the Date Line and has not expanded to the east as one might have expected. This is not your standard El Nino. But the dryness has expanded to the west.
Let us now take a look at the progress of the Kevin wave which is the key to the situation. Since February there have been three successive downwelling Kelvin Waves without really an upwelling Kelvin Wave of any consequence to counter their impact. The first wave which started in February was the most effective at getting this El Nino started. The second wave reinforced to some extent but not much and this third (and I believe last) downwelling Kelvin Wave has created an El Nino that will have a major peak coming soon and an extended life but at a diminished strength. There is a hint of something new at 175W to 160W. This could be another Kelvin Wave but I think it is simply the warm water rising in that area. NOAA has indicated that they think this may be yet another Kelvin Wave. I think that will get resolved soon and I think NOAA may be incorrect on this.
We are now going to change the way we look at a three dimensional view of the Equator and move from the surface view to the view from the surface down. When I examine the current situation as compared to the 1997/1998 El Nino which I described graphically recently, the current El Nino has developed more rapidly. This El Nino is a couple of months further along in its evolution than the 1997/1998 El Nino and will end earlier in the winter than the 1997/1998 El Nino. Also the 1997/1998 had a slightly larger amount of warm subsurface water in the Eastern Pacific and that water takes time to surface, create convection, and thus cool. Something happens to allow the Easterlies to resume their strength and that in turn moves this water back towards the Western Pacific Warm Pool. This El Nino appears to be fading from west to east.
Current Sub-Surface Conditions
Top Graphic (Anomalies)
The above graphic showing the current situation has an upper and lower graphic. The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters.
The top graphic is the most useful of the two and shows where 2C (anomaly) water is impacting the area in which the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to 180W which is very impressive. The small blip over at 180W has basically joined with the warm water that formerly extended only to 160W . The subsurface warm water is making its way to the surface in the Eastern Pacific especially in the vicinity of 110W but also to some extent, until recently, working its way deeper. The 3C anomaly is over to 150W which again is very impressive and which now encompasses at least 50% of the Nino 3.4 Measurement Area for the ONI. One can see how the ONI has continued to increase.
One big issue is where will the +6C and +5C anomaly water go as it reaches the beaches of Ecuador? To the extent it prevents cooler water from reaching the surface, it can enhance convection and impact the Walker Circulation which could then provide positive feedback to this El Nino. But that warm water might tend to go north or south or both and there is some indication that some of it is working its way deeper where it probably will mix with cooler water coming north from further south. The size of the 6C anomaly is reduced from last week and is fragmented into pieces but I do not know if that is real or the way the base used for computing anomalies adjusts with the calendar. The 4C anomaly is no longer intersecting the surface or if so is barely doing so but again I do not know if that is real or the way the anomalies are calculated, displayed etc. but it looks a bit different than last week.This El Nino is peaking now and will soon begin its decline. But it is certainly taking its sweet time probably because of the large amount of the subsurface warm water. Water is a very good insulator: I believe it has the second highest specific heat capacity of all known substances.
It is important to differentiate between anomalies and actual temperature. The warm anomaly shown in the upper graphic is not covered by colder water as it might appear to be in the upper graphic but is shown as a warm anomaly because normally water at those depths is colder than it currently is. That is why this warm anomaly does not simply rise to the surface as warm water would normally do but it is preventing cooler water from entering the area as one would expect as summer transitions to Fall. That is why it takes time for this warm anomaly to dissipate.
So that means that other than by mixing, that warm water under the surface will stay warm until it rises to the surface where it can be cooled by evaporation (while making clouds) or moves to the north where it will impact Mexico and the Southern Coast of the U.S. That is part of the basis for models predicting that the ONI of this El Nino will continue to rise.
Bottom Graphic (Absolute Values which highlights the Thermocline)
The bottom half of the graphic is not that useful in terms of tracking the progress of this Warm Event as it simply shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event and you can see that the cooler water is not yet fully making it to the surface to the east along the coast of Ecuador. However, one now can see the increase in the slope of the thermocline (look at the 25C dividing line for example which has now reached the surface). We can now begin to monitor the 20C Isotherm which is often thought of as being the middle of the thermocline where the slope is also steepening and looks like it may reach the surface fairly soon. I have been saying that for a while but there has been essentially no change. We may want to pay more attention to the 28C Isotherm as west of that temperature is where convection is more easy to occur. Right now that Isotherm intersects the surface near 130W which has been the case for some time but it appears to have moved a bit to the west. .
TAO/TRITON GRAPHIC
Taking a close look at the TAO/TRITON graphic but first let us compare last Sunday’s situation below to the most recent graphic shown below it.
With the current situation. There is quite a bit of difference. The warm water is further east and intensified. The Easterlies are further suppressed which may explain the shift in the anomalies. We now see a large area of 3C+ anomaly. So far there are few if any impacts on CONUS of this intense El Nino other than those related to the Pacific Cyclones. So this raises real questions about how we measure an El Nino and how we do regression analysis on historical El Ninos to predict weather.
I calculate the ONI each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W ONI measuring area into five subregions (that I have designated A through E (from west to east) with a location bar shown under the TAO/TRITON Graphic) and have mentally integrated what I see below and recorded that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions.
———————————————– | A | B | C | D | E | —————- |
So as of Monday October 12 in the afternoon working from the October 11 TAO/TRITON report, this is what I calculated which is bit higher than my calculation last week.
Anomaly Segment | Estimated Anomaly |
A. 170W to 160W | 1.7 |
B. 160W to 150W | 2.2 |
C. 150W to 140W | 2.5 |
D. 140W to 130W | 2.6 |
E. 130W to 120W | 2.8 |
Total | 11.8 |
Total divided by five subregions i.e. the ONI | (11.8)/5 = 2.4 |
My estimate of the Nino 3.4 ONI after rounding has increased to 2.4 with much more of a gradient from west to east. NOAA has today again reported the weekly ONI as being 2.4 and that is certainly a very high level for an ONI even though it is a weekly value not a three-month average. The base used to calculate the anomalies changes with the calendar and I do not have those numbers so it is a little hard for me to tell if the surface is actually warming or if what is happening is that the surface temperature is remaining constant and the base declines as winter approaches so a constant surface temperature records as an increased anomaly. In theory I could compare the graphics from week to week and perhaps figure that out. This warm water or at least warmer than normal for this time of year certainly impacts the weather in Ecuador and Peru but may not have a direct impact on weather in CONUS other than by spawning tropical cyclones which move north and enter the circulation of troughs off of Baja California which then enter CONUS. It gets complicated because it seems that north of the Equator the water is definitely warmer and that is where tropical storms form.
Nino 4.0 is now reported as being 1.0 a slight decrease. The action which I think is most important to track is in Nino 1+2 which is now reported as being up to 2.7 which is high and insignificantly lower than last week. One issue remains the extent to which warm water off of Ecuador and Peru impacts CONUS weather. I think it has very little impact and that is what we are seeing right now. The other issue is that most El Ninos decay from east to west so it will be observed most clearly first in Nino 1+2 and we are not seeing that yet.
This is summarized in the following NOAA Tables and I am showing both the table for last week and the updated table.
And here are the values this week.
There is almost no change. I think this El Nino has now peaked!
One wonders about these calculations as they appear to not be related to the “adjusted” version of the NOAA forecast model which was discussed last week. So it is not clear to me how this El Nino will be officially recorded. July-August-September has been recorded as having an ONI of 1.5. In the above graphic eyeballing it you might conclude that the three months were observed as being 1.6, 2.0 and 2.3. So the impact of adjusting these observed values to what is considered “adjusted” is not obvious to me.
Although I discussed the Kelvin Waves earlier, now seems to be the best place to show the evolution of the subsurface temperatures.
The conditions down to 150 meters have not changed in a long time. But now we see the warm anomaly at depth over by Ecuador beginning to dissipate. I think the Humboldt Current is beginning to overpower the impact of the Kelvin Waves. It is a slow process.
SST Surface Anomaly Hovmoeller
Here is another way of looking at it: Unlike the Upper Ocean Heat Anomaly Hovmoeller (I call it the Kelvin Wave Hovmoeller) which takes an average down to 300 meters, this just measures the surface temperature anomaly. It is the surface that interacts with the atmosphere. As you can see the warm water rising off the South American Coast had (or at least the value of the anomaly when calculated) worked its way all the way over to beyond 170W so it fully contributes to the increasing ONI but the western edge of the warm anomaly is showing some signs of stalling and drifting to the east. So far the various graphics many of which are looking at the same information from a different perspective are not indicating to me that there is a new Kelvin Wave although NOAA has suggested that we may indeed have a new Kelvin Wave. But I think they may not be correct and although they have mentioned it in their ENSO Report today they did not draw it in. If there is another Kelvin Wave it could get very interesting.
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El Nino in the News
There as a report out of Brazil on the impact on agriculture but I was not able to find a full article in English.
Each week I make a point to note that the major impact of El Nno so far has been on Indonesia and here is a distressing article on that.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
First the Temperature and Precipitation Departures from four months ago (Ending Date June 13)
Then the same graphic one month later (Ending Date July 11)
And then the same graphic (Ending Date August 8).
And again five week later (Ending Date October 10, 2015)
This provides a four-month sequence of snapshots of the four-week departures from normal as this El Nino has progressed.
You can see these four graphics as well as I can and it is difficult to describe the changes that have taken place over four periods of time because of the large number of changes. Currently we see:
- A general pattern of fairly extreme warm anomalies in the West
- More dry areas than wet areas in CONUS with much of the dry areas contiguous and in the Northwest and the Great Plains. The east coast is wetter than climatology. We are starting to see some El Nino impacts in the Southwest. The pattern in Mexico has become less dry.
View from Australia
El Nino
I do not see much change from the graphic released two weeks ago. Here is the discussion just released:
Issued on 13 October 2015
While the 2015 El Niño is the strongest seen since 1997, its equivalent in the Indian Ocean—the positive Indian Ocean Dipole (IOD)—is now at levels not seen since late 2006. The strong El Niño is expected to last until at least the end of the year before declining in the first quarter of 2016, however the positive Indian Ocean Dipole is expected to decay earlier in November 2015.
Sea surface temperatures (SSTs) in the central to eastern tropical Pacific continue to warm, further entrenching El Niño, while waters south of Indonesia have cooled, strengthening the positive IOD. Likewise, waters to the north of Australia have also cooled over the past three weeks, which may further contribute to drier conditions.
Most international climate models surveyed by the Bureau of Meteorology indicate the anomalous warmth in the tropical Pacific Ocean is likely to peak around the end of 2015. Typically, El Niño peaks during the late austral spring or early summer, and weakens during late summer to autumn.
Four out of five international climate models suggest the strong positive IOD event will persist into November, but decline rapidly as the monsoon trough shifts south over the IOD region, changing the wind patterns. This change means the IOD pattern is no longer able to form in the ocean.
IOD (Indian Ocean Dipole)
Again I do not see much change from the graphic released two weeks ago. It comes with only a very short discussion and here is the key part of that discussion. The last sentence was confusing as it referred to the El Nino not the IOD so I did not include it.
The positive Indian Ocean Dipole (IOD) event persists, with the weekly index value to 11 October strongly positive at +1.18 °C. This is the highest weekly value since the very strong positive IOD event of 2006.
Sea surface temperatures (SSTs) in the Indian Ocean are warmer than average over much of the basin, and the southern Indian Ocean as a whole has been at record temperatures in recent months (see timeseries of winter anomalies). A positive IOD event is typically characterised by cooler-than-average water off the coast of the Indonesian island of Sumatra (see About the Indian Ocean Dipole). Cool anomalies in this area can be seen in the Sea surface temperature section.
Positive IOD events are often associated with lower rainfall in parts of central and southeastern Australia. Positive IOD events are more likely to occur during El Niño, which also is typically associated with a reduction in winter–spring rainfall in eastern Australia.
Until recently, very warm sea surface temperatures across much of the Indian Ocean were likely moderating the influence of these two climate drivers on Australian climate. See the updated Climate Outlook for further discussion of the interplay between all three influences.
To me it is interesting that the IOD appears to have peaked and is on the way down. But the interrelationship between the IOD and El Nino is complicated and not fully understood.
Putting it all Together.
We are in El Nino conditions now. The actual impacts on CONUS are not clear. We started in the Spring by having wetter conditions than usual in the Southwest but that has tapered off quite a bit. Last week we had serious flooding in South Carolina and the Bahamas but it is not clear that this event was related to this El Nino but everything is connected. The El Nino is probably influencing the IOD to tend towards being positive thus providing a double whammy for parts of Asia and Australia but this is projected above to continue for only a month or two. That by itself should make us wonder what exactly is going on.
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. There does not seem to be an obvious match to any prior El Nino in the modern era which to me means there is no model to use to predict impacts.
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 and may be moving back to PDO Negative. But for now we do have PDO+. The AMO being an overturning may be more predictable so the Neutral status moving towards AMO- is probably fairly reliable but not necessarily proceeding in a straight line as indeed the storm track for hurricanes in the Atlantic is suddenly unusually warm.
So in terms of long-term forecasting, none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast. The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.
We are beginning to speculate on the winter of 2016/2017 which I believe will tend to be ENSO Neutral but I am not so sure that it will not lean towards being a cool event or at least closer to a La Nina than neutral. One thing is fairly certain for the U.S. it will be less wet and warmer than the winter of 2015/2016 which will be quite wet and cool but perhaps for a shorter portion of the winter than NOAA has been predicting. JAMSTEC is predicting that the Spring of 2017 will begin a mild La Nina. That is a long way to make a prediction for a number of reasons including the Spring Prediction Barrier. The below is the CPC/IRI forecast and for the first time it is showing the probability of ENSO Neutral exceeding the probability of El Nino in the May-June-July time frame and the probability of La Nina is creeping up.
TABLE OF CONTENTS FOR PART II OF THIS REPORT The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page II where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
A. Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks (Usefully bookmarked as it provides automatically updated current weather conditions and forecasts at all times. It does not replace local forecasts but does provide U.S. national and regional forecasts and, with less detail, international forecasts)
B. Factors Impacting the Outlook
1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)
2. Medium Frequency Cycles such as ENSO and IOD
3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.
C. Computer Models and Methodologies
D. Reserved for a Future Topic (Possibly Predictable Economic Impacts)
TABLE OF CONTENTS FOR PART III OF THIS REPORT – GLOBAL WARMING WHICH SOME CALL CLIMATE CHANGE. The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page III where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.
D2. Climate Impacts of Global Warming
D3. Economic Impacts of Global Warming
D,4. Reports from Around the World on Impacts of Global Warming.