Seeder feeder rain issue

Large volumes of rain have fallen on Stornoway over the last ten days with particularly heavy rain on Monday.

Stornoway Gazette weather correspondent Dr Eddie Graham of Lews Castle College said it had not broken any records but that there had been 85mm (3.35inches) over the nine days before Monday and 32.4mm on that day alone.

There was a weather warning in place for the north west of Scotland and flooding on the mainland caused travel disruption for those travelling to and from the islands on Monday and Tuesday as roads were closed across the Highlands due to flooding and land slides.

Dr Graham explained more about the reason for the significant rainfall: “It’s called the “seeder-feeder” mechanism, whereby “average”-sized raindrops falling from a high frontal cloud-band fall down “seeding” low-level clouds lying over the mountain summits.

Whilst passing through these dense, water-rich clouds, they rapidly “feed” upon that cloud’s droplets, making the resulting raindrops much bigger - yielding a greater quantity of rain at the surface.”

The Scottish Government’s Resilience Room (SGoRR) was chaired by Transport Minister Keith Brown on Monday to discuss the heavy and prolonged rain affecting the north west.

The A82 was closed between Ballachulish roundabout and Fort William after a landslip and between Ullapool and Inverness due to flooding. The A835 heading for Ullapool was also subject to closures leading to calls for more improvements to the area.

It wasn’t just the rain causing inconvenience but also strong winds impacting ferries. The maximum gust of 67mph was recorded at Stornoway on Saturday which was stronger than that during the ex-hurricane Gonzalo.