On the 26th October, a quickly deepening depression moved across Scotland into the northern North Sea. Strong winds on the north west and western side of the depression brought winds gusts to over 90mph across the NE Scottish mainland, which despite being used to such winds brought an early taste of winter to these  parts.

The depression began life to the south west of the UK. A depression was anchored to the west of Iberia during the 24/25th, somewhat cut off from the main cross Atlantic flow (Fig 1). During the 24th, a strong transatlantic jet began to cross the North Atlantic and picked up the slow moving upper trough. The low to the south west contained a large amount of high wet bulb potential temp (WBPT) air (>16C at 850mb); however, further north, cold arctic air was massing to the east of Iceland, poised to move south west and being steered by high pressure over Greenland.  The scene was set for a clash of airmasses – right over Scotland.

During the 25th the upper jet was moving towards the UK. A sharp shortwave at 300mb & 500mb was located within this flow (see fig 2). SW Ireland was ahead of the shortwave and in a favourable location for pressure falls to occur. This created an elongated pressure trough which eventually let to the development of a new depression which began to develop over SW Ireland and move north east.

Overnight during the 25/26th a large warm advection field moved north across the UK, outbreaks of rain breaking out widely across the UK, (radar shown in Fig 3). This moved north overnight with some large totals. In a 24 hour period, on the 25th (to 09Z 26th) Altnaharra (Sutherland) recorded 61.6mm, Rackwick (Orkney) 60.1mm and Kinbrace  (Sutherland) 56.6mm. Further south in Yorkshire even Bingley (W.Yorks) recorded 54.6mm. Over the 25th-26th, 48hr rainfall totals (to 09Z 27th) included Rackwick with 117.5mm, Altnaharra with 98.4mm and Kirkwall (Orkneys) 86.6mm.

By daybreak on the 26th the developing low was over Western Scotland, at around 976mb with developing easterly gales in the Northern Isles and northerly storm force winds off of NW Scotland. Water vapour (WV) imagery indicated forcing was now affecting the depression and deepening was continuing (WV imagery is shown in Fig 4). North Rona island (in the very far north) saw consistent winds all day above storm force with mean winds at 12Z of 72knts (and it is likely gusts were higher than the 84kts recorded). 

As the day progressed the low pressure slipped east to lie off the east coast of Scotland by the end of the afternoon, deepening to around 971mbs (see high resolution visible imagery in Fig 5). The strong NE’ly winds on the north west side of the depression led to exceptionally strong gusts across the north east of Scotland and the Northern Isles. Lerwick and Wick reporting some of the highest wind speeds (see below)

                        Lerwick             Wick

15Z                   64 Knts                        

16Z                   70 Knts             52 Knts

17Z                   74 Knts             77 Knts

18Z                   69 Knts             71 Knts

19Z                   66 Knts             53 Knts

Damage and flooding was reported across the Northern Isles. Thousands of people were left without power and 40 people had to be rescued from their flooded homes in Dingwall by lifeboats. On mainland Scotland, the police told people not to travel in Rosshire, Caithness and Sutherland due to the danger of falling trees and a train from Glasgow to Inverness was hit by tree branches on the line, although no one was hurt. The track itself was washed away at Helmsdale.

On the 27th the depression continued to move east, bringing storm force winds to the coasts of Scandinavia and plenty of rain and snow across the Baltic and into Sweden and Finland.

Of note (and visible on the HRV image, Fig 5) are the largely clear skies across England during the afternoon. The airmasses descent, following the cold front, led to largely sunny skies. The residual high WBPT airmass also allowed some unusually high temperatures for late October with 19.6C recorded at Wisley and 20C at Margate in Kent. Both are notable for the 26th October, especially with the 90mph gusts being recorded at the time at the other end of the country.

Summary : An early season storm which developed as a result of a strong sharp thermal contrast and a good upper level trough and strong jet stream. Had the contrast been slightly further south then the depression would have been bringing much stronger winds further south across the more populated areas of Scotland.

Copyright P Blight 2006

Grateful thanks to Philip Eden for some rainfall data totals.

Additional material : Dave Wiseman