The Twelfth Joint Meeting for the Seasonal Predictionof the East Asian Winter Monsoon
JMA, Tokyo, Japan
10-11 November 2011

Summary
The Twelfth Joint Meeting for the Seasonal Prediction of the East Asian Winter Monsoon took
place in Tokyo from 10-11 November, 2011. More than 30 experts from 15 countries
including China, Japan, Mongolia and Republic of Korea attended the meeting.
The meeting summarized outlooks for the coming winter 2011/2012 as follows:- The La Niña event, which returned in this autumn, will continue during the coming winter.
The strength of the La Niña event will be weak or moderate.
- The East Asian winter Monsoon will be near normal or weaker than normal in the northernpart of East Asia and near normal or stronger than normal in its central and western parts
during the coming winter reflecting the predicted La Niña conditions. However, it should betaken into account uncertainties of the prediction caused by the limited predictability ofinternal variability of the atmosphere such as the Arctic Oscillation (AO).
- The recent warming trend maybe decreases the interannual cold tendency.
The meeting agreed that exchanging the latest scientific knowledge and views relevant to theAsian monsoon system, such as those on long-term trend, decadal variability, ENSO andinternal variability in the atmosphere, as well as predictabilities of these phenomena, would
contribute to improving seasonal outlooks related to the Asian Monsoon. It noted that theJoint Meeting would be an ideal occasion for such purposes.
Considering that WMO’s Regional Climate Outlook Forum (RCOF) process is similar to theorganization of the Joint Meeting, the meeting noted that the Joint Meeting could berecognized as another RCOF in the future. China, Japan, Mongolia and Republic of Korea
will make continuous efforts to turn the Joint Meeting into a sub-regional climate outlookforum.

The meeting was pleased to note that Republic of Korea will host the 13th Joint Meetingfor the Seasonal Prediction of the East Asian Winter Monsoon.
decided later.

The time and place will be1. Introduction
The 12th Joint Meeting for the Seasonal Prediction of the East Asian Winter Monsoon washeld in Tokyo from 10-11 November, 2011. The Joint Meeting has been hosted by China,Korea, and Japan in turn since 1998. Mongolia joined the Joint Meeting in 2009. This year,invitations were also extended to Bangladesh, Cambodia, Indonesia, Lao PDR, Malaysia,Myanmar, Pakistan, Philippines, Sri Lanka, Thailand and Viet Nam, which is expected tostrengthen regional networking. The meeting was attended by more than 30 experts fromthe 15 countries.
In session 1, China, Japan and Korea presented their current status and future plans of
seasonal forecasting. In session 2, the meeting reviewed recent researches related to the East
Asian Monsoon. In session 3, presentations were made on overview of recent climate overEast Asia, El Niño/La Niña outlooks, and seasonal outlooks using statistical and dynamical
forecast models. In session 4, the meeting discussed the presented outlooks and agreed onits summaries.
In this report, monitoring results and outlook on ENSO is given in section 2, and outlooks for
winter 2011/2012 is shown in section 3. In section 4, remarks on seasonal forecasts aresummarized. Section 5 includes the agreed plan on the future meetings of the Joint Meeting.

2. Monitoring and Outlook on ENSO
Summary: The La Niña conditions, which returned in this autumn, will continue into thecoming winter. The strength of the La Niña conditions will be weak or moderate.

CMA: La Niña conditions came back to the tropical Pacific again in early September 2011,and have gradually enhanced in strength thereafter. Jointly considering most results of ENSO
model forecasts, La Niña is expected to strengthen and continue through the Northern
Hemisphere winter 2011-12.
KMA: Current weak La Niña condition is continued until the end of 2011 and gradually
recovers to neutral.
JMA: In October 2011, La Niña conditions are present in the equatorial Pacific.
that La Niña conditions will decay between winter and spring.
Others:

It is likely

Summary of ENSO Outlook
La NiñaCMA○KMA○

JMA○Neutral

El Niño

3. Outlook of 2011/2012 Winter Monsoon
Circulation:
Summary: The East Asian winter Monsoon will be near normal or stronger than normal
during the coming winter reflecting the predicted La Niña conditions. However, it should betaken into account uncertainties of the prediction caused by the limited predictability ofinternal variability of the atmosphere such as the AO.

CMA: The correlations between three indices of the East Asian winter monsoon (EAWM)
and several related factors (such as SST, La Niña, the SCS summer monsoon, AO, and theArctic sea Ice) were examined. It seemed that most of factors would support a strong
EAWM in 2011/12 winter. BCC’s CGCM predicts that the Siberian High and East Asian
winter monsoon are stronger than normal.
KMA: The Eurasian snow cover is about to increase recently so that the Siberian High isweaker than normal. The AO is not strong compared to last year and is not significant. The
anomalously strong MJO activity over Indian Ocean causes Middle Asia to be warm
anomalously. Therefore, the 2011/12 winter monsoon is forecasted to be weaker thannormal, and the Korean peninsula to be near/warmer and wetter than normal.
JMA: JMA’s CGCM predicts that the Aleutian low is weaker than normal, and thesubtropical jet stream shifts southward over Japan in the coming winter. Such predictedcirculation features are considered to be forced by SST anomalies in the tropics including theLa Niña event which are predictable. Although the CGCM predicted the neutral phase of theArctic Oscillation (AO), which has severe impact on the EAWM, the spread among eachensemble member is large and the 30 years hindcast shows that the CGCM does not haveenough skill to predict the AO. Considering all the above, the EAWM is predicted to beweaker than normal in the northern part of East Asia, and stronger than normal in the southern

part with huge uncertainties.
Others:Decadal trends and others:
Summary: The recent warming trend maybe decreases the interannual cold tendency.

CMA: Temperatures have turned into the warm period over China in winter since the end of1970s. The decadal trend tendency maybe decreases the interannual cold tendency.
KMA: Recent decadal trend of winter temperature is near of above normal.
JMA: The tropospheric thickness temperature averaged over the mid-latitudes of the NH,
which is positively correlated with temperatures over Japan is predicted to be above normal.

Temperature and Precipitation:
Variables

Temperature

Precipitation

CMA-: Most China except for Northeast Less than normal on the whole.
and Southwest China
More rainfall regions only
The decadal warming tendency locatedovermostInnermaybe decreases the interannual Mongolia,
mostNortheast
cold tendency
China.
SomepartsofSouthwest China and lower
reaches of the Yangtze River.

KMA0/+: All parts of Korea+: All parts of Korea

JMA0+: Northern Japan
0: Eastern and Western Japan
0-: Okinawa/Amami

0+: Pacific side in Northern
Japan0-: Okinawa/Amami
0: Other areas

Mongolia

0/-: Western part of Mongolia
0: Rest of part

0:Southeast and Southwest ofMongolia+: Rest of part

4. Remarks on seasonal forecasts
Cooperation among NMHSs and climate research communities should be maintained or evenenhanced to improve accuracy and effective use of seasonal forecasts in East and Southeast
Asia.
The interpretation of prognostic products should be based on common scientificunderstanding of important phenomena, such as the Asian Monsoon, ENSO, the Arctic
Oscillation, the Circumglobal Teleconnection (CGT), and climate change including decadal
variations, which are considered to have close relationship with climate variability in East
Asia. The understanding of meteorological and climatological phenomena should be shared
among forecasters, modelers, and scientists who are engaged in seasonal forecasts in theregion. The participants appreciated that the joint meeting worked as a fruitful mechanism
to foster the common understanding.
The limited predictability should always be taken into consideration when seasonal forecasts
are prepared. In this sense, comprehensible verification of seasonal prediction products
should be shared among NMHSs in the region.

5. Other issues
 Host of Joint Meeting for the East Asian Winter Monsoon in 2012
Republic of Korea will host the 13th Joint Meeting for the Seasonal Prediction of the EastAsian Winter Monsoon. The time and place will be decided later.