JEDDAH — Moderate to heavy thunderstorms that could lead to flash floods are forecast across parts of Jazan, Asir and Al-Baha, as well as the highlands of the Makkah and Madinah on Sunday, according to the National Center for Meteorology (NCM). The thunderstorms are expected to be accompanied by hail and active winds stirring up dust and sand, while fog may also form over parts of the highlands in those regions as well as over parts of Najran an…