2018 Asia summer forecast: Drought, flood risks to arise from uneven monsoon; West Pacific may yield strong typhoons
An uneven southwestern and eastern Asia monsoon may lead to areas of drought and recurring flooding during the summer of 2018.
The weather pattern that brought areas of isolated flooding rain, frequent dust storms and damaging winds from the Middle East to northern India will break down over the rest of May.
"Until the southwest monsoon kicks in, heat will take center stage," according to AccuWeather Senior Meteorologist Eric Leister.
Southwestern monsoon impacts
While the southwestern monsoon is forecast to start off in typical fashion with near- to slightly above-average rainfall across India, some inconsistencies may develop during the middle and latter part of the summer.
"We expect the southwest monsoon to become more streaky during July and August with active and inactive periods," according to AccuWeather Lead Global Meteorologist Jason Nicholls.
Breaks of dry weather may lead to insufficient rain and areas of drought in northwestern and southeastern India, as well as southern and central Pakistan.
"One area that monsoon-based storms and rainfall may frequent through the summer is from India's Odisha and West Bengal regions to portions of Uttar Pradesh and Madhya Pradesh," Nicholls said.
While isolated flooding can occur anywhere during the monsoon, these northeastern and north-central states have the best chance for episodes of flooding that may reach regional levels.
Spatially, areas of drier-than-average conditions will outweigh areas that have above-average rainfall in India, Pakistan and Bangladesh from the monsoon.
Other effects from the southwestern monsoon include the typical low clouds, drizzle and spotty rain along the southwestern coast of Oman and the southeastern coast of Yemen.
Much of the Middle East will be seasonably dry with above-average temperatures.
"Dust storms may be still more common this summer [compared to other summers]," Nicholls said. "Occasional thunderstorms are likely over the mountains of southwestern Saudi Arabia and western Yemen."
Meanwhile, typical warmth is in store along the eastern and northeastern shores of the Mediterranean Sea.
East Asia monsoon impacts
A different monsoon than that which affects the countries bordering the northern Indian Ocean coast affects a large part of southeastern Asia near the west coast of the Pacific Ocean.
There is the potential for this east Asia monsoon to progress northward at a slow pace and result in a zone of excessive rainfall.
"Enough rain may fall on China's Yangtze Valley to result in flooding that endangers lives and causes damage to property and agriculture," Nicholls said.
Adequate rainfall for crops is likely over much of the rest of central and eastern China, the Korean Peninsula and southern Japan.
Farther north and west, abnormally dry conditions that develop may evolve into drought from parts of north-central and northeastern China to Mongolia during the middle to latter part of the summer.
"These same areas where drought is a concern may also experience rounds of heat that can lead to poor air quality and health-related issues," Nicholls said.
Additional areas where drought may occur
Drought may also affect parts of western and southeastern Asia.
Below-average rainfall and near- to above-average temperatures are forecast from northern and eastern Turkey to portions of Kazakhstan this summer.
"Drought conditions may hit the Volga Valley region hard enough to stress crops severely," Nicholls said.
Another area that may become very dry is in Indonesia and Malaysia.
"Typical showers and thunderstorms are in store into mid-summer," Nicholls said. "But, if an El Niño develops, rainfall may become much more sparse late in the season.
West Pacific typhoon season may yield more super typhoons than in 2017
Anticipated conditions are likely to yield a greater number of typhoons and super typhoons during 2018 when compared to 2017.
During the first part of the summer, a near-average number of direct impacts from tropical storms and typhoons is forecast for Vietnam and southeastern China.
"One parameter suggests a greater number of tropical storms and typhoons to curve later this summer and into the autumn," Kottlowski said.
A significant impact is a landfall or the remnants of a tropical storm or typhoon that causes significant flooding, damage and loss of life.
This projected average pathway may steer storms away from Vietnam and southeastern China but may bring more storms with significant impacts to south-central China, Taiwan and southern Japan.
"There is also the potential for more significant impacts to the Philippines this season, compared to last year," Kottlowski said.
"As long as wind shear diminishes as we suspect it will and above-average water temperatures continue over the prime development region near the Philippines, there's also the potential for more typhoons and super typhoons this year compared to last year," Kottlowski added.
Should El Niño develop during the late summer or autumn, then overall numbers of tropical storms, typhoons and super typhoons could be greater than average for the season as a whole.
The main effect that El Niño has on the western Pacific is to make the prime tropical storm and typhoon development area significantly larger than during neutral conditions.
Elsewhere, during the summer months, the most active month for tropical cyclones is likely to be June for the Bay of Bengal and the Arabian Sea for tropical depressions to form, strengthen and perhaps impact land.
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