Super Typhoon Yagi still leaves huge impact in northern Thailand and Myanmar although it downgrades to low-pressure area

Seven northern and central provinces especially Chiang Rai and Chiang Mai provinces are among the hardest hit by the low-pressure area further downgraded from Super Typhoon Yagi in the north of Myanmar

Flash floods, massive runoffs, and overflows in major tributaries in Chiang Rai and Chiang Mai have wreaked havoc and left people stranded suddenly since the early morning as Super Typhoon Yagi further downgraded to a low-pressure area in Myanmar but is still generating storms and heavy rains in the areas.

Combined with the Monsoon Trough over the northern skies and the south-westerly winds blowing from the Andaman Sea, it’s expected that the North of Thailand and some other parts of the country will be hit hard in the next three to five days (until Sep 16), according to the Office of National Water Resources.

So far, more than 14,000 households especially in Chiang Rai, Chiang Mai, Sukhothai, and Phitsanulok have been affected by the incidents, according to the Disaster Prevention and Mitigation Department (DDPM). This afternoon, the government issued a special warning to the residents of Chiang Rai’s downtown to move their belongings to higher grounds or evacuate immediately as the overflows and floodwaters keep rising quickly.

Powerful Yagi

Originating as a tropical storm in the western Philippine Sea on Sep 1, Yagi then crossed the northern Philippines before moving westward toward the South China Sea. As described by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), on Sep 2 Typhoon Yagi made landfall in Casiguran, Aurora in the Philippines. It continued to traverse mainland Luzon then slightly weakened as it interacted with the mountains of Northern Luzon before accelerating over northern Luzon and intensifying into a typhoon. 

The Philippine government reported on Sep 4 that in 8 regions, 27 provinces, 142 cities and municipalities, there had been 228 reports of flooding, with 12 deaths and nearly 20 people getting injured or missing. Up to 547,000 people were affected, with about 64,000 being displaced and almost 600 homes being damaged.

The storm then quickly strengthened into a strong typhoon on Sep 4 when it entered the South China Sea. As reported by the Joint Typhoon Warning Center (JTWC), its maximum sustained winds had increased to 222 km/h (138 miles per hour), equivalent to a Category 4 hurricane. As the environment was favourable, it was projected by NASA to turn into a Super Typhoon with maximum wind speeds expected to reach 244 km/h (150 mph) before making landfall.

l Typhoon Yagi made landfall in northern Vietnam (TIme lapse, Sep 7-9, 2024). Credit: CSU/CIRA & NOAA/NESDIS/ RAMMB-CIRA Satellite Library

On Sep 6, Yagi lashed China’s island province of Hainan near Wenchang city, resulting in four deaths and 95 injuries, with a total of 526,100 people in 19 cities and counties in the province being affected, according to the Department of Emergency Management of Hainan Province. It also caused 720,000 people in Guangdong to evacuate later, Global Times reported.

The next day (Sep 7), it made landfall in northern Vietnam as one of the strongest typhoons the country has seen in over a decade, resulting in extensive flooding, landslides, and casualties across 26 provinces with Quang Ninh and Hai Phong provinces being the most affected. 58 fatalities and 40 missing persons were reported during Sep 7-9, with 746 people getting injured due to landslides and flash floods, over 52,000 individuals being evacuated, and 47,566 houses being reportedly damaged or destroyed, according to ReliefWeb. (As of Sep 12, more than 150 deaths have been updated.)

With its powerful wind speeds, Typhoon Yagi has been registered as the second most powerful tropical cyclone in the world so far this year after Hurricane Beryl, which struck Jamaica in early July, and as the strongest storm in Asia this year. 

Stronger storms and climate change

Thailand never experienced impacts brought by such powerful storms until late 2022 when it was hit by the tropical depression downgraded from Super Typhoon Noru. Climate scientists have observed the trend of storms on this side of the world and said they appear to be getting stronger in recent years, and warmer oceans may be fuelling their destructive power.

Euro News reported that scientists now say that typhoons, hurricanes, and cyclones in general have become stronger due to climate change, and this is because warmer ocean waters allow storms to pick up more energy leading to higher wind speeds. A warmer atmosphere can hold more moisture meaning more intense rainfall.

As explained by Euro News, all tropical cyclones feature very high wind speeds, heavy rainfall and storm surges, which temporarily cause sea levels to increase. Named differently in different parts of the world as hurricanes, typhoons and cyclones, they are all like giant spinning engines, which use warm, moist air as fuel. 

The storms usually start in tropical waters near the equator, when this air rises up and away from the surface of the ocean. Less air near the surface causes an area of low pressure and the surrounding air swirls in to replace it. The warm, moist air cools off as it rises, forming clouds and the whole system begins to spin. It rotates faster and faster until an eye forms in the centre and high-pressure air from above then flows down into this calm centre of the storm.

l Noru rapidly intensified and became a Super Typhoon (TIme lapse, Sep 24-25, 2022) Credit: CSU/CIRA & JMA/JAXA/ RAMMB-CIRA Satellite Library

According to Euro News, the storms need sea surface temperatures at least 27C to gain enough energy to start spinning. They go counterclockwise north of the equator and clockwise south of it. The storms usually begin to weaken once they hit land as they no longer have the energy from the warm ocean waters to feed them. The strongest on the scale of a tropical storm in this area is a super typhoon which is equivalent to a Category 5 hurricane.

There is also evidence that these powerful storms are lingering over land for longer due to climate change, leading to heavier rainfall in specific locations, Euro News reported. In addition, rising sea levels may be playing a role in the severity of these tropical cyclones and storm surges can devastate coastal communities and already elevated sea levels only make this flooding worse.

Euro news quoted IPCC as reporting that the number of tropical cyclones around the world is unlikely to increase, but more may reach the highest levels of intensity as the world warms. Another study published in July this year also revealed that tropical cyclones in Southeast Asia are now forming closer to coastlines, intensifying more rapidly, and lingering longer over land.

So far, the ONWR has issued a warning that the areas could face flash floods and massive runoffs until Sep 18. The heavy rainfall will also increase water levels in the Mekong River in Chiang Rai down to the northeastern provinces of Loei and Ubon Ratchathani between 0.5 to almost four meters, resulting in flooding in some provinces with the water levels between 0.5 to 2.5 metres. 

Some disaster mitigation experts have criticised the government for being too sluggish in dealing with the situation. Their warnings have not reached people and there are no proper mitigation plans in place when the weather becomes extreme.