近日，深圳进入今冬最冷周，来自北方的冷空气造成较强的雨雪天气，市气象台在全市发布寒冷黄色预警信号，提醒市民做好防寒保暖工作。请看本报周五的报道:

    The Shenzhen Meteorological Observatory issued a yellow alert Thursday as Shenzhen is forecast to experience its coldest weather in five years this weekend.The chill from the north, said to be the strongest in five years for the city, will start to affect the city Friday and is expected to bring temperatures to as low as 4 degrees Celsius on Monday.

    报道中的alert就是“预警”的意思。天气预警一般分为蓝（blue）、黄（yellow）、橙（orange）、红（red）四个颜色级别，严重程度依次加重。