Tasmanian police have expanded a large air and sea search overnight for a teenage kayaker feared missing at sea, as a severe weather alert for the area is issued.
Valentine Bester, 19, was reported missing by friends at 5.30pm on Thursday after setting off from Lauderdale Yacht Club at Roches Beach, east of Hobart, at 11am.
Police believe he may have been trying to travel across an ocean opening to Lime Bay, by following the Seven Mile Beach and Carlton Beach coastline in his green kayak.
An air and sea search was underway on Thursday night in Frederick Henry Bay, involving the Westpac Rescue Helicopter, two marine boats, and the Dodges Ferry Volunteer Marine Rescue Unit.
A severe weather warning for parts of eastern, southern and central Tasmania is current, with winds peaking at 100 kilometres per hour in the search area.
Police are appealing to members of the public who may have seen the teen to come forward with any information.