The temperature in Hong Kong will drop to 12 degrees Celsius (54 degrees Fahrenheit) on Thursday, forecasters said, reminding the elderly and the sick to take precautions.There will be a few rain patches on Thursday with temperatures falling significantly during the day and becoming cold, according to the Hong Kong Observatory, as an intense replenishment of the northeast monsoon reaches the coast of Guangdong.It will be the coldest day in the city since the beginning of the year.Cold mornings…