August, 2019 Seasonal Forecasts. Part II, NOAA Comparison with JAMSTEC

Written by Sig Silber

We published the NOAA Long-Term Forecast Friday Night and it can be accessed here. In Part II we compare the NOAA forecast for Alaska and CONUS with the JAMSTEC forecast and also provide some explanation for the differences. Given the general acceptance of ENSO Neutral being our future for the next few seasons, there are really substantial differences in the NOAA and JAMSTEC temperature and precipitation forecasts for Alaska and CONUS and of course, we also provide the JAMSTEC World Forecasts. We also pay special attention to Europe.

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Now we compare the two NOAA forecasts with the JAMSTEC forecast. We do it again later in the article in more detail but the comparison here may be easier to see. The first image is the Early-August IRI-CDC ENSO probabilities. The second image is the JAMSTEC proprietary forecast model for the Nino 3.4 Index. The third is the NOAA proprietary model CFSv2.

CPC Probabilities

Nino 3.4 JAMSTEC one year as of August 1, 2019

CFSv2 August 19, 2019

They are not lined up perfectly but one can easily compare them. The model results are a bit different. Two forecasts are shown for NOAA. It is not always clear which they use. More than likely they at least place more weight on the IRI-CPC forecast. Later we see the JAMSTEC Modoki Index which may play a large role in the differences in the forecasts for this Fall.

As you can see there is not a lot of agreement on the Nino 3.4 forecasts. The JAMSTEC forecast is similar to the NOAA Statistical forecast not shown but as per their discussion in Part I of this Report was rejected as not being reliable. A statistical forecast puts a lot of weight on persistence and can be considered a quasi-Markovian type of forecast i.e.the current state (or perhaps the recent history) is the predictor of the future state. That does not mean that the future state will be the same as the current state for example if the pattern was that El Nino’s typically last for X months and then they transition to ENSO Neutral, that would influence the forecast. I am not sure how JAMSTEC makes their forecasts. But it will be clear when we look at the temperature and precipitation forecasts that the differences within an overall agreement that we are in ENSO Neutral are enough to produce large differences in the forecasts.

That is not surprising as this past El Nino had Nino 3.4 readings of from 0.5C to 1.0C or a variation of 0.5C and ENSO Neutral goes from -0.5C to +0.5C a range of 1.0C. So there is a lot of potential variation within ENSO Neutral and we know that JAMSTEC considers many other two-year cycles in addition to ENSO. So there is plenty of room for variation in the forecast within a consensus that we will be in ENSO Neutral. Plus JAMSTEC still shows we are starting out in El Nino “Modoki-Like” conditions through this Fall.

One of the reasons for doing this comparison is it provides the ability to create our own updated forecast as we see the assumptions made by each agency be confirmed or not. That is especially true when the actuals start coming within the range of the two sets of assumptions. Weather is not linear so it is more complex than scaling the solution to where the actuals are showing up relative to the two versions of the assumptions but with a little imagination one might be able to sort it out. You will be able to better understand what I have just said as we look at the two different forecasts.

C. Now to our full report. (Sections A and B were covered in Part I which can be accessed here)

This report is organized into a summary that has two tables of graphics that show the temperature and precipitation forecasts for the upcoming three seasons, a brief discussion of the ENSO assumptions by both NOAA and JAMSTEC and then the JAMSTEC Agency discussion and then a comparison of the two forecasts which is basically an expansion of the summary table.

Summary of the NOAA and JAMSTEC Forecasts

For those who want a quick synopsis of the two forecasts, below is a summary of the temperature and precipitation forecasts for three time-periods and from left to right the NOAA forecast for Alaska and CONUS (the contiguous mid-latitude U.S), then JAMSTEC for North America (which includes Canada and Mexico), and then JAMSTEC for Europe and surrounding areas. Larger graphics are provided later in the report. (the graphics in the Summary Table are not set up to be clicked on to enlarge). The Summary Table is kind of a tease to keep you reading but you can see the evolution of the weather pattern through Fall, Winter, and then Spring. For some readers, these two sets of summary graphics may be all the information they wish to look at and that is fine.

In addition to the value of comparing the JAMSTEC and NOAA forecasts, the JAMSTEC forecast by showing North America provides more context for the Alaska and CONUS Forecasts as the temperature and precipitation patterns cover North America, not just Alaska and CONUS. Similarly, when I extract Europe from the JAMSTEC World Map, I include enough of North Africa and Eurasia to provide context.

Temperature

	NOAA Alaska Plus CONUS	JAMSTEC North America	JAMSTEC Europe
Fall SON 2019
Winter DJF 2019-2020
Spring MAM 2020

I thought it would be useful to summarize my comments from the later detailed analysis. Here they are. Fall: Fairly similar except importantly JAMSTEC shows cool for South-Central CONUS but not the East Coast. Winter: JAMSTEC shows a remnant of the Mississippi Valley cool anomaly but shifted a bit farther east, a cool southern Alaska while NOAA shows an EC North-Central area. Spring: Here there is major disagreement as the NOAA EC area is instead warm for JAMSTEC and JAMSTEC shows a cool anomaly in the southern Tier and East Coast. So that is the season with the most disagreement with respect to temperature.

For Europe, it is Fall: warm, Winter: warm except the British Isles and most of Scandinavia and Spring: warm but North Africa and part of the eastern Mediterranean cool.

Precipitation

	NOAA Alaska Plus CONUS	JAMSTEC North America	JAMSTEC Europe
Fall SON 2019
Winter DJF 2019-2020
Spring MAM 2020

I thought it would be useful to summarize my comments from the later detailed analysis. Here they are. Fall: total disagreement. For Winter, it is again total disagreement. NOAA is fairly non-committal about Spring other than a wet eastern Alaska but JAMSTEC only slightly agrees with that and has a very dry forecast for CONUS except for North Carolina and Virginia.

For Europe it is Fall: mixed, Winter: with a dry north and wet south and Spring: dry.

We provided the full NOAA Discussion in Part I. The much shorter JAMSTEC Discussion was just published so we have that for our Report tonight.

Aug. 19, 2019 Prediction from 1st Aug., 2019
ENSO forecast:
As predicted earlier, the El Niño Modoki-like state is observed now. The SINTEX-F predicts the El Niño Modoki-like state will persist until late autumn. We need to be careful of its impact, as it may be different from that of the canonical El Niño. Then, the whole tropical Pacific is expected to be warmer-than-normal during winter.
Indian Ocean forecast:
As predicted earlier, a positive Indian Ocean Dipole quickly emerged in May and now persists. The model predicts that the positive Indian Ocean Dipole will persist in autumn, and then quickly decay in winter. We may observe co-occurrence of a positive Indian Ocean Dipole and an El Niño Modoki-like state in summer and autumn; this is as we observed in 1994 and 2018.
Regional forecast:
On a seasonal scale, SINTEX-F predicts that most part of the globe will experience a warmer-than-normal condition in boreal autumn, except for southeastern U.S.A., southern part of the South American Continent, and eastern Russia. In boreal winter, most part of the globe will still experience a warmer-than-normal condition, except for some parts of Alaska, U.K., Scandinavia, some part of northern India, southwestern China, and eastern Russia.
As regards to the seasonally averaged rainfall in boreal autumn, a wetter-than-normal condition is predicted for western coastal area of Canada, southern part of Chili, southern West Africa, most part of Southeast Asia. In contrast, some parts of U.S.A., Brazil, western Russia, most part of India, Indonesia, Philippines and Australia will experience a drier-than-normal condition. Some of them will be partly due to the expected positive Indian Ocean Dipole (see schematic of a positive Indian Ocean Dipole event: http://www.jamstec.go.jp/aplinfo/sintexf/e/iod/about_iod.html). In particular, we notice that Indonesia and Australia may experience extremely drier than normal condition, owing to the expected co-occurrence of a positive Indian Ocean Dipole and an El Niño Modoki-like state. In boreal winter, a wetter-than-normal condition is predicted for western coastal area of Canada, northwestern U.S.A., northeastern Brazil, some parts of southern Africa, Europe, India and southern China. In contrast, eastern U.S.A., southeastern Brazil, eastern part of southern Africa, Scandinavia, western Australia, Indonesia and Philippines will experience a drier-than-normal condition.
The model predicts most part of Japan will experience warmer- and drier-than-normal in autumn as a seasonal average. In winter, most part of Japan will be still warmer, but slightly wetter-than-normal.

It is useful to look at the forecasts for the Nino 3.4 Index used to determine if the Sea Surface Temperatures meet the criteria for an El Nino(+0.5 C or higher). Here is a brief summary of the Indices of the two Agencies and how they compare. Three of these graphics were presented earlier. We use them again here and add two more to provide a more detailed analysis.

	One Year	JAMSTEC Two Years
JAMSTEC
	CFS.v2	CPC-IRI Probabilities
NOAA
	Comparing the one-year JAMSTEC NINO 3.4 graphic above to a similar period for both the NOAA models, one sees a difference namely the move towards pure Neutral or even a slight La Nina Bias in the NOAA models and more of an El Nino Bias in the JAMSTEC model.	The IRI/CPC forecast uses different units namely probabilities rather than absolute levels of the NINO 3.4 Index
	The so-called Modoki index is interesting because it clearly indicates a Modoki or a Modoki bias early in the forecast. This index has been confusing but not this month. It is initially at El Nino Modoki Levels but only differs from the other JAMSTEC Nino 3.4 forecasts in the SON period.

We see differences in the pattern of how things may evolve. But what about the SOI. Does it confirm that the Sea Surface Temperatures are causing the atmosphere to react in a way that results in ENSO Neutral weather? We address that after the following discussion and a look at the subsurface. .

Indices use a single number to convey information. Sometimes it is useful to look at the forecast Sea Surface Temperatures that correlate to the indices. I believe that the SST’s directly correlate with the JAMSTEC Nino 3.4 Index and their forecast but NOAA uses a variety of tools so it is not so easy to understand exactly how they do their forecast but there is a lot of information on that in their lengthy discussion which was presented in our Part I Report.

NOAA	JAMSTEC

Do not be distracted by the choice of colors by the two agencies. The NOAA graphics are more brilliant but one needs to concentrate on the patterns, not the artistic appeal. For JAMSTEC we have graphics here for each season but for NOAA we do not have a graphic for MAM 2020 but they had FMA 2020 so we used that instead.

I do not see a lot of difference in the Pacific. They both show the Modoki for SON 2019 but NOAA does not recognise a Modoki even they funded some of the research. JAMSTEC shows El Nino or close to El Nino conditions for DJF 2019 – 2020 and NOAA does not. There is a lot of difference in the North Atlantic (South of Greenland) and we do not know what to make of that. NOAA is showing a cool area off of West Africa and JAMSTEC is not. It would take a lot of study to really assess the differences in these two forecasts of the sea surface temperatures.

Updates from JAMSTEC can be found here. Updates from NOAA can be found here. You have to look for the SST row and go to the right where it says “normalized with mask” and click on E3 which provides the latest model run.

All of these forecasts depend to a large extent on what is known about subsurface temperature anomalies. Here is the latest [pentad not penatd] analysis. Updates can be obtained here.

This is a cross-section along the equator. In general, the Equatorial Current moves from west to east. So the warm anomaly moves east and then either “erupts” to the surface due to subsurface ridges that direct the current up or bumps into the coast of Ecuador and is forced to the surface and then drifts west due to the prevailing easterlies. Cool water can enter from the south namely the Humboldt Current/Peruvian current water coming up from Antarctica. So the models are really estimating the timing of the subsurface anomalies reaching the surface. The warm anomalies are not warmer than the water above them but simply warmer than normal for the current season.

Compared to last month, there is really not that much change. But the eastern Pacific cool anomaly is a bit larger and the Central Pacific warm anomaly is a bit smaller/weaker.

Does the SOI confirm that El Nino Conditions apply? The SOI is one measure of the extent to what the atmosphere has been impacted by the Eastern Pacific surface pattern which is measured by the Nino 3.4 Index. After all, we are more interested in the impacts to weather in the atmosphere which impacts populated areas than we are about the temperature distribution of the ocean surface along the Equator in the Pacific Ocean.

I am showing the situation this month and last month.

Last Month	This Month

The SOI Index is now dead Neutral and that is a 30 day moving. This graphic is a 30-day average so it changes slowly. Updates to the above “frozen graphic” can be found here.

SOI = 10 X [ Pdiff – Pdiffav ]/ SD(Pdiff) where Pdiff = (average Tahiti MSLP for the month) – (average Darwin MSLP for the month), Pdiffav = long term average of Pdiff for the month in question, and SD(Pdiff) = long term standard deviation of Pdiff for the month in question. So really it is comparing the extent to which Tahiti is more cloudy than Darwin, Australia. During El Nino we expect Darwin Australia to have lower air pressure and more convection than Tahiti (Negative SOI especially lower than -7 correlates with El Nino Conditions). During La Nina we expect the Warm Pool to be further east resulting in Positive SOI values greater than +7).

D. Now we begin our comparison of the NOAA and JAMSTEC Forecasts (Focus on next nine months i.e. three seasons)

In this Update, we compare the JAMSTEC temperature and precipitation forecast maps, which are for the World, with the NOAA temperature and precipitation forecast maps that cover only CONUS and Alaska. We do this primarily for educational purposes.

JAMSTEC works in three-month intervals which correspond to seasons and does not change the selection of months each time they update but does so every three months. At that time they drop one season and add another season further in the future. JAMSTEC provides maps for three seasons and the choice of seasons changes every three months. So for one out of three months, the first season lines up perfectly and this is that month. So for JAMSTEC, we have Fall (SON), Winter(DJF) and Spring (MAM) and we are using the same for NOAA in the comparison.

I show the NOAA Maps first followed by the JAMSTEC maps. I extract North America from the Worldwide JAMSTEC map and use that to compare with the NOAA Maps. I also extract Europe including parts of North Africa and Western Asia from the Worldwide JAMSTEC maps and include those excerpted maps in the summary table at the beginning of this article.

Now we will compare the maps in that summary but with full-sized maps.

Fall SON 2019

Temperature for NOAA

And here is the SON 2019 temperature forecast for North America that I extracted from the JAMSTEC World Forecast.

Mostly agreement but JAMSTEC shows a cool anomaly for the MIddle and Lower Mississippi Valley. That is a pretty big difference.

And now the JAMSTEC WORLD FORECAST (for this graphic my comments are mostly related to areas other than Alaska and CONUS as those comments appear with the larger graphics above)

It is pretty much warm all over. One can see a pattern of a cool southern South America and eastern Siberia.

Precipitation

NOAA

And here is the SON 2019 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast.

No Agreement here. It is pretty dramatically different.

And now the JAMSTEC WORLD FORECAST (for this graphic my comments are mostly related to areas other than Alaska and CONUS as those comments appear with the larger graphics above)

Australia is dry, Indochina, Indonesian, and The Philippines are dry and eastern Brazil is dry. India is somewhat dry. Western Russia is dry.

Winter DJF 2019/2020

Temperature

NOAA

And here is the DJF 2019-2020 Temperature Forecast for North America that I extracted from the JAMSTEC World Forecast.

Disagreement here. JAMSTEC shows Southern Alaska to be cool and the Eastern Third of CONUS to be EC while NOAA shows the North Central CONUS to be EC.

JAMSTEC WORLD FORECAST

It is mostly warm. Eastern Siberia is cool. The British Isles and part of Scandinavia are cool. Northeast India and Tibet are cool.

Precipitation

NOAA

And here is the DJF 2019/2020 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast.

There is almost no agreement here. There is disagreement over Alaska. NOAA shows a wet Northern Tier but centered on the North Central and JAMSTEC shows a wet Northwest. There is agreement that part of California will be dry but not full agreement on what part of California.

JAMSTEC WORLD FORECAST

Southern Europe and the eastern Mediterranean are wet, South Africa is wet India is wet. Northern South America is wet. Western Australia is dry.

Spring (MAM – 2020)

Temperature

NOAA

And here is the MAM -2020 Temperature Forecast for North America that I extracted from the JAMSTEC World Forecast.

There is agreement on Alaska. NOAA has an EC area for the North Central CONUS. JAMSTEC has that area warm but the southeastern third or more of CONUS cool. So that is a big difference.

JAMSTEC WORLD FORECAST

Ireland is cool, North Africa is cool and the Eastern Mediterranean is cool. Greenland is cool as is eastern Canada. Some parts of southern Africa are cool. The rest of the World is warm.

Precipitation

NOAA

And here is the MAM 2020 NA precipitation I extracted from the JAMSTEC World Map

NOAA is not willing to commit itself other than with respect to Alaska where there is some limited agreement with JAMSTEC. For JAMSTEC, the Northwest is dry and the eastern half of CONUS is dry except for South Carolina, North Carolina, and Virginia which are wet. The lee side of the Rocky Mountains/Great Plains are pretty much EC except for Wyoming, Colorado, Northeast New Mexico and Northwest Texas which are slightly wet.

JAMSTEC WORLD FORECAST

Europe and European Russia are dry. Indochina is dry. Australia is mostly dry, Eastern Brazil is dry. Southern Africa is wet. The Maritime Continent is wet.

D. Conclusion

Both NOAA and JAMSTEC have forecasts that in one way or another incorporate the ENSO Neutral Phase except that JAMSTEC sees SON to be “El Nino Modoki-Like”. It seems that NOAA just does not like calling a westerly displaced El Nino a Modoki. We now have the JAMSTEC discussion and it looks like they are showing SON 2019 to be somewhat like an El Nino Modoki. They use the term “Modoki-Like” since the pattern did not originate as a Modoki but currently appears to be similar to the late stages of a Modoki.

Slight changes in the ENSO Phase are likely to change the actuals from what has been forecast. I do not have a lot of confidence in either of the forecasts but for different reasons. NOAA may not be properly taking into account the Modoki aspect of the situation which casts doubt on their SON 2019 forecast and JAMSTEC may be overestimating the El Nino Bias that is in their forecast which casts doubt on their DJF 2019-2020 forecast.

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August, 2019 Seasonal Forecasts. Part II, NOAA Comparison with JAMSTEC

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There Is No Great Salt Debate: We Should Be Consuming Less

This Week In Doom 18August 2019

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