Heavy Rain Warning Issued for the Western Hills

Up to eighty millimetres could fall on high ground by Sunday.

A yellow warning for heavy rain has been issued for the western hills above Calder, covering Harrow Moor, the upper Ardle valley and the hill villages from 6pm on Friday until midnight on Sunday. Forecasters say 40 to 60 millimetres of rain is likely across much of the warning area, with up to 80 millimetres possible on the highest ground.

The regional forecasting office said a slow-moving band of rain associated with an area of low pressure in the west would arrive on Friday evening and stall over the hills through Saturday. A second, heavier pulse is expected late on Saturday night into Sunday morning before the system clears east during Sunday afternoon.

Timings and areas

The warning is expected to unfold in three stages:

• Friday 6pm to midnight: rain spreading in from the west, heavy at times on the moor, with strong south-westerly winds gusting to 50mph on exposed ridges.
• Saturday: persistent rain over the hills, lighter but still steady in the valley and Calder itself. Totals of 20 to 30mm likely by Saturday evening on high ground.
• Saturday night to Sunday midday: the heaviest spell, with rates of 10mm an hour possible for several hours over Harrow Moor and the hill villages. Rain clearing from the west during Sunday afternoon.

Forecasters say the city and the coast, including Port Selwyn, are likely to see lower totals of 15 to 25mm, but surface water may still cause problems on roads and in low-lying streets of the old town.

Rivers and roads

The main concern is the River Ardle and its upland tributaries, which respond quickly to rain on the moor. Ground in the western hills is already wet after a damp autumn, meaning more of the rain is expected to run straight off into streams and rivers.

The regional environment agency said flood alerts were likely to be issued for the Ardle between Coldwater and the town of Ardle on Saturday, and that river levels could peak on Sunday afternoon or evening, some hours after the rain has stopped. Its flood duty officer, Gwen Halloran, urged people living near rivers and streams to check the latest alerts over the weekend.

“The rain will stop on Sunday, but the water will still be coming down off the hills into the evening,” said Halloran. “People often relax when the sky clears. That is exactly the moment the Ardle is at its highest. Please keep checking until Monday morning.”

Highways staff warned of difficult driving conditions on the moor road between Harrow Moor and the upper valley, which is prone to flooding at the dip near Kell Bridge and to small landslips on the steeper bends. The council said gritters and drainage crews would be on standby, and that the road could be closed at short notice. The 41 bus may be diverted if the road floods.

What to do

Residents in the warning area are advised to clear drains and gutters before Friday evening, secure loose items in gardens, and move valuables upstairs if they live in properties that have flooded before. Drivers should avoid travelling on the moor road unless necessary and should never attempt to drive through floodwater: thirty centimetres of moving water is enough to float a car.

Walkers planning to head on to the hills this weekend are urged to postpone. The Harrow Moor mountain rescue team said streams that are easy to step across in dry weather can become impassable within an hour, and that it had been called out twice in similar conditions last winter to walkers cut off on the wrong side of a beck.

Calder United’s home match on Saturday is expected to go ahead, though the club will inspect the pitch on the morning of the game. Several weekend events in the hill villages, including the Coldwater craft fair, have already been postponed. The forecasting office said the warning could be upgraded to amber if computer models continue to show the heaviest rain lingering over the moor. A further update is due at 11am on Friday. Drier, colder weather is expected to follow on Monday, with the first widespread frost of the season possible by Tuesday morning.