1. Monitoring and Outlook of ENSO

According to WMO report issued in April 2024, the tropical Pacific is currently in an El Niño state. There are 11 forecasts of the ENSO phase in this FOCRAII forum. All of them believed the El Niño will decline further and transition to ENSO-neutral conditions or La Niña state during June-August 2024.

2. Consensus prediction of precipitation and temperature for JJA 2024

a) Summer monsoon prediction

Based on scientific understanding on the mechanism of Asian summer monsoon and interpretation of climate model products, and according to the definition of summer monsoon intensity by the Beijing Climate Center, the East Asian summer monsoon is predicted to be normal to weaker during the coming summer. Meanwhile the South Asia summer monsoon will be normal to stronger. In JJA 2024, the western Pacific subtropical high will be stronger than normal and the position is normal to westward.

b) Precipitation prediction

The predictions of precipitation are based on possible influence of external forcing factors and summer monsoon circulations. The deterministic consensus prediction is shown as Fig. 1A. The prediction results in this figure are obtained from the feedback of our survey. The results of probabilistic precipitation prediction from seven dynamical models or multi-model ensemble including ECMWF, CFSV2, JMA, APEC, BCC, C3S, and CMME are shown as Fig. 1B.  

c) Temperature prediction

The deterministic temperature prediction indicates that the temperature is above or near normal over Asia during the coming summer in almost all the regions (Fig. 2A). The probabilistic predictions from dynamical models show similar results (Fig. 2B). So heatwave should be paid much more attention for Asia.

d) Tropical cyclone activity

BCC predicts the total number of tropical cyclone (TC) over the northwestern Pacific and South China Sea will be below normal in 2024, with a range of 21-24 (1991-2020 climate mean number is 25), and 6-8 TCs will land in China (climate mean number is 7). Typhoons mainly affect the eastern part of South China and the coastal areas of East China. It should be noted that the frequency of the influencing TC varies significantly for different countries or regions. Here we only list the prediction of BCC. 

3. Methods used in Predictions

The methods used in prediction are surveyed for all participants. The results showed that most predictions made by both dynamical and statistical methods. 

Based on these surveys, the details of precipitation and temperature prediction for JJA 2024 by different participants are also synthesized and shown in Fig. 1A and Fig. 2A respectively. It should be kept in mind that the predictions in Fig 1 and 2 contain uncertainty in some particular areas. Therefore, caution should be taken in using the information. It remains as a future challenge to seek methodologies for appropriate representing uncertainty of prediction. In addition, it is stressed that these predictions are relevant only to seasonal time scales and relatively large areas. 

Fig. 1A Deterministic precipitation prediction for summer 2024 from feedback. (A: above normal; N: near normal; B: below normal)

Fig. 1B Precipitation prediction from dynamical models for summer 2024. (Blue column: above normal; Gray column: near normal; Red column: below normal)

Fig. 2A The same as Fig. 1A, but for temperature.

Fig. 2B The same as Fig. 1B, but for temperature. (Red column: above normal; Gray column: near normal; Blue column: below normal)