Forecasters expect gusts of seventy miles an hour on exposed headlands.

An amber wind warning has been issued for the coast and the western hills from 3pm on Thursday until 9am on Friday, as the fourth named storm of the season approaches from the south-west. Forecasters expect gusts of 60 to 70 miles an hour on exposed headlands, with 50 to 55 miles an hour likely in Calder and along the valley. A wider yellow warning for wind and rain covers the whole region from Thursday morning until Friday evening.

The storm, the fourth in seven weeks, is forecast to deepen rapidly over the open sea on Wednesday night before tracking north-east across the region. The strongest winds are expected between 8pm on Thursday and 3am on Friday, coinciding with high tide at Port Selwyn shortly after midnight.

Where and when it will be worst

The amber area covers the headland, Port Selwyn, the estuary shore and the upper slopes of Harrow Moor. Forecasters say the most dangerous period on the coast will be the hours around the midnight high tide, when large waves are likely to overtop sea walls and promenades. Inland, rainfall totals of 30 to 50 millimetres are expected, with up to 70 millimetres on high ground above the valley, raising the risk of flooding on smaller rivers and streams.

The River Ardle, already high after a wet fortnight, is expected to rise sharply on Friday morning as rain drains from the hills. The environment agency has issued flood alerts for the Ardle between the town of Ardle and the city, and warned that further alerts may follow on Thursday evening.

“Four storms in seven weeks is unusual but not unprecedented. What makes this one more concerning is that the ground is saturated and the rivers have had no time to recover, so the same amount of rain will cause more problems than it would have a month ago,” said Dr Anwen Castellane, chief forecaster at the regional weather centre.

Why so many storms?

Dr Castellane said the run of storms was linked to a strong, persistent jet stream across the ocean, which has been steering one area of low pressure after another towards the coast since late September. Unusually warm sea temperatures to the south-west have also given the systems extra energy as they develop. She cautioned that it was too early to say whether the season would continue in the same pattern, but noted that long-range models suggested the jet stream would remain active until at least the middle of December.

Scientists at the University of Calder’s climate group have been tracking the frequency of named storms since the naming scheme began nine years ago. The current season is on course to be the busiest on their records, although they said a single season could not by itself show a long-term trend.

What to do

Emergency planners are urging people in the amber area to prepare on Thursday morning rather than waiting for the wind to rise.

  • Secure garden furniture, bins and trampolines before 3pm on Thursday.
  • Avoid coastal paths, promenades and harbour walls from Thursday afternoon until Friday midday.
  • Do not drive through floodwater; 30 centimetres of moving water can float a car.
  • Charge phones and keep a torch to hand in case of power cuts.
  • Check on elderly neighbours and anyone who lives alone.

Rail operators have warned of a reduced timetable on the coast line from 6pm on Thursday, and the late ferry to the islands has been cancelled. Speed restrictions will apply on the high road over Harrow Moor, which may close entirely if gusts exceed 70 miles an hour. Power companies have placed extra repair crews on standby across the hill towns, where outages lasted up to two days after the last storm.

Conditions are expected to ease from Friday afternoon, though blustery showers will continue into the weekend. Forecasters will review the warning on Wednesday evening and may upgrade parts of the coast if the storm deepens faster than expected.