Source

Storm ‘Gero’ (Harwood, 2012) developed over the coast of the northwest US on 8^th January 2005 and moved northeastwards, passing to the north of the UK and crossing over Scandinavia. On 11^th January, the storm approached Ireland and combined with, and was enhanced, by another low-pressure system located south of Iceland. The central pressure deepened rapidly to about 950 mbars as the storm approached to the northwest of Scotland. The strongest wind gusts of 111 knots [57 m/s] were recorded at Great Dun Fell, Cumbria (Met Office, 2012). It has been suggested that this event took place within a 5 month period during the last 30 years when storminess was higher than normal (Dawson et al. 2011). A few days earlier, during 7^th–9^th January, storm Gudrun had already passed over the British Isles, Scandinavia and Finland, causing a record storm surge and dramatic shoreline changes on the Estonian coast (Wolf, 2007).

The storm generated a skew surge of between 0.5 and 1.5 m all the way from Holyhead around to Dover. Water levels exceeded the 1 in 5 year return level at 8 sites in Scotland and Whitby. The event generated the highest record return period water levels at 5 sites in Scotland. The highest return period water level was at Tobermory and was 1 in 71 years. The next largest return period of 1 in 70 years was at Kinlochbervie. Here, the 1 in 5 year threshold was exceeded twice on two consecutive high waters, with skew surge values of above 1.0 m. The highest skew surge was at Tobermory and was 1.51 m.

A study which deployed a suite of nested wave models to hindcast this event, suggested the local wave setup was very high, approximately 0.5 m at South Uist, due to large wave heights (up to 14.3 m) entering and rapidly shoaling near-shore (Wolf, 2007; Wolf, 2009). This may have contributed substantially to the total water level.

Pathway

We are unaware of specific information regarding the flood pathways for this event.

Receptor and Consequence

Severe flooding occurred in the Hebrides (Harwood, 2012) and damage was concentrated in Scotland (Met Office, 2012). Tragically, 5 persons were killed when two cars were swept from a causeway on South Uist (Cramb, 2005). Throughout Scotland, roofs were damaged, trees were blown down, roads, bridges, ferry and rail services affected and more than 60,000 people left without electricity (Weathermaster, 2011). A school in Balivanich was damaged, and was later relocated (Richards & Phipps, 2007). In the Shetland Islands, Sumburgh Airport was closed for 3 days and key road links were out of action also (Ball et al. 2008). There was also considerable coastal erosion in some places (Dawson et al. 2011), with severe impacts to areas west of the causeways that link North Uist and Benbecula, Benbecula and South Uist and South Uist and Eriskay (Muir et al. 2013). This storm is also associated with rainfall flooding and three fatalities in Carlisle (Cumbria). In the north of England, there was flooding in quayside areas of Newcastle when the River Tyne burst its banks (BBC, 2005).

During an unspecified time in January 2005, there was coastal flooding Warkworth, Northumberland (Northumberland County Council, 2010). The sea level data indicates this is very likely to have occurred on the 12^th January.

Coastal flooding was also reported at Bryggen, Norway (Vannstand.no, 2014).

In the region of Scotland that was affected, the storm is considered the worst in living memory, although from a meteorological standpoint a more severe storm occurred on 11^th–12^th November 1877.

Summary Table