Sept 14 (Reuters) - Indonesia"s exports and imports likely continued to surge in August, driven by high prices of the country"s main commodities like coal and palm oil, a Reuters poll showed on Tuesday. A survey of 18 economists forecast the economy"s August trade surplus had shrunk to $2.36 billion from $2.59 billion in July. Southeast Asia"s biggest economy has been enjoying an export boom on the back of robust commodity prices, allowing for a trade surplus every month since May of 2020. Economists expected 36.9% annual growth in August exports, accelerating from 29.32% in the previous month. August imports were seen rising 45.1% on a yearly basis, compared with 44.44% in July.