Mumbaikars can expect a very rainy week ahead as the signs were already there on Monday evening. Heavy downpour was witnessed in several areas as low-lying clouds ended up dumping a lot of rain in the city for a few hours in the evening. Five NDRF teams have been deployed in the city in view of the heavy rain forecast. The IMD in its five-day forecast said heavy to very heavy rain is likely in Mumbai and Thane till Friday.