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In December 2021, Super Typhoon Rai caused significant devastation to the South Philippines and East Malaysia. In the meantime, an unprecedented flood event occurred in Peninsular Malaysia at 2,000 km west of the typhoon's path, causing comparable socioeconomic impacts as Rai. Record‐breaking 3‐day precipitation was received by Peninsular Malaysia during 16–18 December. Based on the storm tracking results, this study identified two mesoscale convective systems (MCSs) that were directly responsible for the flooding. The two MCSs were directly initiated by a tropical depression and sustained by an elongated easterly water vapor corridor originating from the Super Typhoon Rai. The return period and joint frequency analysis of key drivers indicate that the 3‐day downpour was more severe than a "once‐in‐a‐century" event. Historical records suggest such anomalous moisture channel has become more frequent in Southeast Asia, which alarms heightened attention in forecasting winter flood. Plain Language Summary: On 16–18 December, Peninsular Malaysia received a record‐shattering 3‐day precipitation, resulting in catastrophic socioeconomic impacts. Due to the temporal coincidence with Super Typhoon Rai but far away in space, there were speculations that there might be a teleconnection between the two events. Our results reveal that their relationship could be more straightforward. Based on the analyses of storm tracking database and synoptic data records, we found that two consecutive mesoscale convective systems were responsible for the heavy precipitation, which were produced by a tropical depression that hovered over the peninsula. Meanwhile, Super Typhoon Rai provided a long‐range water vapor transport, akin to adding fuel (i.e., moisture) to the engine (i.e., the tropical depression), and therefore, the precipitation over the peninsula was significantly enhanced. Such long‐range moisture transport has become more frequent during the boreal winter season, posing an increasing risk of flooding in Southeast Asia. Key Points: A stretched moisture channel from Typhoon Rai and a strong tropical depression are key synoptic drivers for the flooding eventReturn period and joint probability of key drivers indicate that the 2021 Peninsular Malaysia flood was more severe than "once‐in‐a‐century"There is an increasing trend in such anomalous moisture channel, suggesting a rising risk of severe flooding in Southeast Asia [ABSTRACT FROM AUTHOR]

Guided by the Paris Agreement, the IPCC Special Report on Global Warming of 1.5 °C reported potential risks of climate change at different global warming levels (GWLs). To provide fundamental information on future temperature extremes over Southeast Asia (SEA), projected changes in temperature extreme indices are evaluated for different seasons at 1.5 °C and 2 °C GWLs against the historical reference period of 1976–2005 based on the ensemble of CORDEX simulations. Results show that the temperature indices increase significantly across the Indochina Peninsula and Maritime Continent at both GWLs except for decreasing daily temperature range (DTR) in the dry season, with more pronounced magnitudes at 2 °C GWL. Moreover, the regionally averaged ensemble medians of the indices show various changes over different subregions. At 1.5 °C and 2 °C GWLs, most pronounced increases of threshold indices. i.e. summer days (SU) and tropical nights (TR), are projected in Sumatra and Sulawesi for both wet and dry seasons. The warm spell duration (WSDI) increases generally, with strongest magnitudes for Sumatra and Sulawesi (Philippines and Sulawesi) in the wet (dry) season. On the other hand, significant increases of warm days and nights can also be observed at 2 °C GWL compared to 1.5 °C, particularly in the dry season, suggesting the high sensitivity of temperature extremes over the SEA. The projected potentially conspicuous temperature extremes under global warming of 1.5 °C and 2 °C primarily concentrate on the densely populated coastal regions of the main islands, showing the necessity of restricting global warming to 1.5 °C aiming at the eradication and reduction of regional climate stress for the human system in the developing countries over the SEA. [ABSTRACT FROM AUTHOR]

Restricting warming to 1.5°C would significantly reduce the regional and local climate risks, including water resources, food security and agricultural production over Southeast Asia (SEA), a tropical region where human society is particularly vulnerable to climate change. Projected changes have been evaluated in extreme precipitation-based indices using the latest available CORDEX simulations covering SEA. The results provide relatively detailed information on the future precipitation changes expected for the countries in the Indochina Peninsula (ICP) and Maritime Continent with the frequency and intensity of precipitation extremes being strengthened at both 1.5 and 2°C global warming levels (GWLs). Predominant changes in most of indices, such as R10mm/R20mm (Heavy / Very heavy precipitation days), SDII (Simple daily intensity) and R95pTOT / R99pTOT (Precipitation of very / extremely wet days) are more pronounced at the 2.0°C GWL than at the 1.5°C GWL. Additionally, significant differences of the indices mainly focus over Maritime Continent, indicating the high sensitivity of the precipitation extremes to the GWL changes over that area. The present study reveals the global warming at either 1.5 or 2 °C level may have implications for the climate vulnerability over SEA. The index evolutions indicate an intense increase of extreme precipitation events over this region in a warmer future. [ABSTRACT FROM AUTHOR]