Storm Event

One of a series of storms during the Christmas period and a big coastal flood event in parts of the UK

Severity ? 3

Source

The storm developed over Canada on 21st December 1999 and moved northeast deepening to a central pressure of approximately 957 mbar by midnight on 24th December (Le Blancq and Searson, 2000). The storm continued to deepen reaching 927 mbar while situated northwest of Scotland (Met Office, 2014). Wind gusts of 60 – 70 knots [31 – 36 m/s] were recorded throughout Scotland; and up to 80 knots [41 m/s] in southern England (Met Office, 2014).

The storm generated a skew surge of 0.7 m at Kinlochbervie (Scotland) and skew surges values of 0.5 m on much of the west and north UK coast (with similar values also recorded at Plymouth and Portsmouth on the south English coast, and Immingham on the east English coast). Water levels exceeded the 1 in 5 year return level at 4 sites (three in Scotland, one in north Wales). The highest return period water level was at Kinlochbervie and was 1 in 23 years. The next largest return period of 1 in 19 years was at Wick (on the northeast coast of Scotland).

The high water on Christmas Eve was a large event at Sefton (Liverpool Bay) with peak offshore wave conditions comprising a significant wave height of 5.39 m (Brown et al. 2010).

Pathway

There was a breach in defences at Selsey, Sussex. We are unaware of any further specific information concerning the flood pathways during this event.

Receptor and Consequence

This event was associated with flooding along the English Channel and Bristol Channel over several days during Christmas 1999, impacting Dorset, Hampshire, Surrey, and Kent (Eden, 2008; Ruocco et al. 2011; Haigh et al., 2015). One newspaper article reported that a favourable change in wind conditions spared “thousands” of homes from flooding. A dozen residential properties were inundated in Totton to over 1 ft. [0.3 m] in depth, and properties in Lymington were also reported flooded. In Selsey, a breach in the defences led to some flooding, while in some areas pumping was required to remove the flood water (Ruocco et al. 2011). Flooding was also reported on the south coast of Jersey on 24th – the worst event on the island since November 1984. The Brockenhurst-Bournemouth railway line was flooded at Sway New Forest although this lies outside of the tidal floodplain.

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Affected Sites

Name Return Period ? Water Level ? Tide ? Skew Surge ? Date ?
KINLOCHBERVIE 23 6.1 5.4 0.7 24th Dec 1999 08:00
WICK 19 4.38 3.84 0.54 25th Dec 1999 00:45
ULLAPOOL 18 6.3 5.66 0.63 24th Dec 1999 07:30
HOLYHEAD 7 6.6 5.94 0.65 23rd Dec 1999 22:45
WICK 6 4.27 3.9 0.37 24th Dec 1999 12:15

References

  1. Le Blancq, F. W., Searson, J.A., 2000. The 1999 Boxing Day low – some remarkable pressure tendencies. Weather, 55, pp.250–251
  2. Met Office, 2014. Winter storms, December 2013 to January 2014. Met Office. Available at: http://www.metoffice.gov.uk/climate/uk/interesting/2013-decwind [Accessed September 9, 2015].
  3. Brown, J. M., Souza, A. J., Wolf, J., 2010. An investigation of recent decadal-scale storm events in the eastern Irish Sea. Journal of Geophysical Research, 115
  4. Eden, P., 2008. Great British Weather Disasters, London: Continuum UK.
  5. Ruocco, A.C. et al. 2011. Reconstructing coastal flood occurrence combining sea level and media sources: a case study of the Solent, UK since 1935. Natural Hazards, 59(3), pp.1773–1796. Available at: http://link.springer.com/10.1007/s11069-011-9868-7 [Accessed March 27, 2015].
  6. Haigh, I.D. et al. 2015. A user-friendly database of coastal flooding in the United Kingdom from 1915–2014. Scientific Data, 2, p.150021. Available at: http://www.nature.com/articles/sdata201521.