Conditions are favourable for a further advance into the remaining parts of the Konkan and the central Arabian sea, it added.
The observatory issued a high wind-speed warning to fishermen along the Konkan and south Gujarat coasts during the next 24 hours, in view of the cyclonic storm "Nanauk" over the east-central Arabian sea.
Fishermen in Konkan and South Gujarat coasts were alerted about speedy winds
The storm is expected to intensify and move north-westwards slowly and then head towards the Oman coast.
The Indian Meteorological Department said earlier this week that the country would see a below-normal monsoon this year and the government said it was taking all precautions to tackle the situation.
Union Minister of Earth Sciences said the rainfall in India in the 2014 southwest monsoon season is likely to be below normal.