A 'major incident' for Jersey will come into effect at midnight on Wednesday, the government has said.
Islanders have been told to prepare for Storm Ciarán, which is set to bring winds of up to 85mph (136km/h).
The main coastal roads in Jersey were closed to the public from Wednesday evening ahead of the storm.
Meteorologists have confirmed the storm is a so-called weather bomb, due to its explosive power caused by a particularly rapid fall in pressure.
In response to the major incident, the government said a multi-agency situation room had been set-up at the States of Jersey Police Headquarters to help co-ordinate the response and would be operational from midnight.
Roads closed include Victoria Avenue, Havre des Pas, Roseville Street, the south end of Green Street, Cleveland Road and La Neuve Route in St Aubin.
The government has also announced 10 parish halls that would be available for shelter if required.
Sandbags have been put in place along the south coast and on slipways to prevent flooding.
The ferry Commodore Goodwill arrived on Wednesday morning with "extra goods" to ensure supermarkets would be well stocked, including fresh food, the government said.
David Braine, senior broadcast meteorologist for the BBC, said a weather bomb - or explosive cyclogenesis - was a term given by meteorologists to a storm that appeared to intensify rapidly, with its central air pressure dropping at least 24 millibars (mb) in 24 hours.
He said Storm Ciarán was expected to see a pressure drop of 28mb in 24 hours, between 06:00 on Wednesday to 06:00 on Thursday.
"Wind associated with Ciaran like to be gusting 85-95mph [140-155km/h] across the Channel Islands early tomorrow, and across parts of the SW of England between 60-80mph [100-130km/h] in gusts," he said.
States of Jersey Police Chief Officer Robin Smith said islanders should stay indoors on Thursday.
He said: "The important message is only essential travel for all islanders, and that's often code for - 'stay at home', so that's what I urge islanders to do; stay at home, particularly on Thursday and Thursday morning."
The government asked people to only call emergency services "for emergencies", to avoid putting themselves at risk and others to "reduce demand as much as reasonably possible".
Infrastructure Minister Tom Binet said the government had put 200 one-tonne bags of sand at the top of slipways along the south coast, including Havre des Pas and Victoria Avenue.
He said: "They've utilised these one-tonne sandbags where the department historically has had the worst problem.
"Obviously they're taking into account the wind direction, so they're reasonably well up on where to expect the main problems."
Delays to post expected
Jersey Post has said mail would not be able to arrive to the island "until the stormy weather eases".
In August, the island's mail plane was scrapped - the air route had been used to deliver letters and parcels every weekday since 1937.
The service said it expected the boat on Wednesday would "be the last until services are able to safely resume".
"We have extra measures in place to clear the backlog of mail as soon as it arrives on the island but would like to advise customers to expect delays," Julie Thomas, managing director of postal and logistics, said.
Chief Minister Kristina Moore said islanders should not panic buy food or supplies.
She said: "Jersey is a resilient place, we have significant stocks available, particularly in terms of medical supplies.
"We do know there is food to sustain us through this period of time, and anticipated disruption."
Waitrose closed its stores at the earlier time of 19:00 on Wednesday and said the shop would be closed on Thursday.
M&S, Morrisons, Iceland and Checkers Xpress stores are due to open on Thursday, but opening times are remaining under review.
Great Storm 1987
BBC Jersey reporter Robert Hall said people in the island would remember the Great Storm of 1987.
He said local forecasters had said right across the Channel Islands that Storm Ciarán could be as bad as that, and that it was very dangerous for people.
Jersey Met confirmed the storm set to hit would be on par with the one 36 years ago.
The Elizabeth Terminal will close to the public on Thursday and the storm gate in Elizabeth Marina was closed on Tuesday.
Val de la Mare and Queen's Valley reservoirs will be closed to the public.