This summer, the pattern responsible for extensive drought and heat in southeastern Asia will break down enough to bring relief to some nations. Meanwhile, the tropics will spring to life for a time.
Rainfall from the southwest monsoon and the East Asia monsoon is forecast to be more robust this summer due to the weakening El Niño.
JUMP TO: La Niña to develop by late summer| Downpours to ramp up in southeastern Asia, recur in part of Middle East | Stubborn areas of drought may still persist | Below-normal normal number of typhoons, tropical storms anticipated
El Niño is defined by above-average sea-surface temperatures in the eastern and central equatorial Pacific Ocean. These sea-surface temperatures cycle from warm to cool, relative to average, over a several-year period. When the sea-surface temperatures in the same area of the Pacific Ocean are cooler than average for a few months, a La Niña pattern has developed.
"El Niño will transition to neutral conditions early this summer, then perhaps toward a weak La Nina during August or September," according to AccuWeather Chief International Meteorologist Jason Nicholls. "Because of this and other factors, we expect rainfall to return toward average over a large part of India, Malaysia and Indonesia."
The speed at which the cycle trends toward La Niña will contribute to the amount of rainfall.
"If El Niño conditions linger through much of the summer, average or less-than-average rainfall could still occur," Nicholls said. "Conversely, if La Niña conditions develop more quickly, then rainfall could trend to well above average in some areas."
While the East Asia monsoon contributes to a significant amount of rain annually in southeastern China, the region could be significantly wetter than average.
"Rainfall could be excessive in part of the Yangtze River Valley with the possibility of flooding in agricultural and heavily populated areas," Nicholls said.
Rain will significantly ease drought and heat in portions of India, Malaysia and Indonesia.
"Routine pulses of thunderstorms meandering around the Indian Ocean basin could also produce excessive rainfall and the risk of flooding in parts of India," according to AccuWeather Meteorologist Adam Douty.
In the Middle East, higher-than-average Indian Ocean temperatures, especially in the Arabian Sea, have contributed to localized heavy rainfall since last fall.
"We expect this part of the Indian Ocean to slowly cool, relative to normal," Nicholls said. "This might be enough to tone down the number of heavy rain events in the southeastern part of the Arabian Peninsula as the summer progresses."
Until the sea-surface temperature anomaly diminishes, the potential for scattered heavy rainfall will continue over the southern part of the Arabian Peninsula well into the summer.
There are likely to be some areas where the rain struggles, despite the diminishing El Niño. With some exceptions, El Niño greatly suppressed rainfall over a large part of southern Asia since last summer.
An area where rainfall could remain significantly below average during the summer includes the central part of the Philippines to Vietnam, Cambodia, Laos, Thailand and southeastern Myanmar.
Much of this area has been experiencing its worst drought in decades. The drought has taken its toll on the water supply, agriculture and economies in the region.
Especially hard hit has been the center of rice production in Asia: the Mekong River Delta.
As of early May in India, "the combination of excessive heat and drought has decimated crops, killed livestock and left at least 330 million without enough water for their daily needs," according to the Associated Press.
"Heat and drought go hand in hand," AccuWeather Meteorologist Jim Andrews said. "Both typically occur before before the summer rain arrives, but what has been going on during March and April has been exceptional."
Multiple nations in Southeast Asia experienced their hottest temperatures on record for any day of the year during April.
The list of nations that have experienced all-time record highs include Thailand at 44.6 C (112.3 F), Cambodia at 42.6 C (108.7 F), Laos at 42.3 C (108.1 F) and the Maldives at 34.9 C (94.8 F).
On May 19, 2016, India reached its highest temperature ever recorded when the mercury rose to 51 C (123.8 F) in Rajasthan.
Where the rain develops and becomes more frequent, heat will throttle back.
From much of the balance of Saudi Arabia to the Black and Caspian seas, a drier- and hotter-than-average summer is forecast.
Average to slightly above-average warmth with generally average rainfall is in store from Kazakhstan, northern China, Mongolia, central and Far East Russia and North and South Korea.
In terms of tropical activity, a lower number of tropical storms and typhoons are anticipated, relative to last year and the long-term average.
Last year there were 27 named tropical systems, of which 18 were typhoons and eight became super typhoons.
Despite the lower numbers forecast for the entire year, the summer part of the tropical season could be more active than the fall, in terms of impacts to land areas.
"Prior to the anticipated La Niña and less-favorable conditions for tropical systems this fall, low wind shear and warm waters, relative to average, will favor strengthening and a significant number of tropical systems in the western Pacific for a time this summer," according to AccuWeather Tropical Expert Dan Kottlowski.
The threat of direct impact from a tropical storm or typhoon will shift northward over the western Pacific shoreline as steering winds change the track of prospective systems throughout the summer.
"Areas that could be hit through the middle of the summer include the northern part of the Philippines, Taiwan and China," Nicholls said. "Toward the latter part of the summer and into the fall, the main risk area will shift toward Japan."
Should La Niña fail to develop during the late summer and fall, the number of tropical storms and typhoons could be close to average. Should La Niña develop at a fast pace, the number of tropical systems in the western Pacific could be well below average.
In the Indian Ocean basin, the summer tropical threat will be mainly during the early part of the season, as usual.
"There is a risk of one or more strikes by a tropical cyclone over Bangladesh, northeastern and southern India and northern Myanmar, as well as part of northwestern India and perhaps Oman," Nicholls said.
The threat in the Bay of Bengal is in addition to Cyclone Roanu.
People should not let their guard down, despite lower numbers of tropical storms and typhoons forecast. A single strike by a significant system can define a season through great destruction and loss of life.