article_snippet.sent: China's Meteorlogical Centre issued a blue alert as ferocious red sandstorms currently engulfing China swept across the north of China .
article_snippet.sent: China's Meteorlogical Centre has now issued a blue alert for the latest sandstorms to hit the northern regions.
article_snippet.sent: China's four-tier colour-coded weather warning system signifies red as the most severe followed by orange, yellow and blue.
article_snippet.sent: The colour-coded weather warning system designated yesterday's ferocious sandstorm blue in an attempt to forewarn residents .