Think It’s Been Stormy? You Must Have Forgotten The 1990’s
By Paul Homewood
Now that it’s over, let’s take a look back at last month’s stormy weather in the UK.
The Met Office classify it as the windiest month since January 1993. Philip Eden thinks it may be the windiest spell since January / February 1990, when the infamous Burns Day Storm was the first of a run of 12 severe gales over a 6-week period.
In December 2013, there were six gales in all:
Dec 5th, 14th/15th, 18th/19th, 23rd/24th, 26th/27th and 29th/30th. The strongest winds were recorded, both in England and Scotland on the 5th.
How did the month compare then with the 1990’s? Below are the Met monthly summaries. The first is for January 1990.
The month was famous for the Burns Day Storm on 25th Jan. Although not as powerful as the Great Storm of 1987, Philip Eden rates it, in terms of extent, longevity and intensity, as the worst storm of the 20thC. The gust speed of 93 knots record at Aberporth equates to 107 mph.
Remarkably, though, the Burns Day storm was preceded a week earlier by another extremely storm at least as strong as the 5th December one.
But January 1990 was just the start, ushering in yet more storms in February. Again wind speeds got up to well above anything seen in 2013. The gust of 86knots at Hemsby is 99 mph, and Leeds was only slightly lower.
Towyn Floods 1990
And January 1993? Again. wind speeds were well above anything seen last month, with at least 70 knots, or 86 mph, reported every day in Scotland up to the 25th.
If anyone is tempted to blame any of these storms, either the 1990’s or current ones, on “climate change”, it is worth looking at what the UK Climate Projections Report , published in 2012, has to say about storminess, and any connection with climate change.
Severe windstorms around the UK have become more frequent in the past few decades, although not above that seen in the 1920s.
There is considerable interest in possible trends in severe wind storms around the UK, but these are difficult to identify, due to low numbers of such storms, their decadal variability, and by the unreliability and lack of representativity of direct wind speed observations. In UKCIP02, we showed how the frequency of severe gales over the past century, although showing an increase over the past decade or so, did not support any relationship with man-made warming. Alexander et al. (2005) presented an analysis whereby a severe storm event is characterised by a rapid change in (MSLP) (specifically ±10hPa in a 3h period); this is different from the severe gales in UKCIP02. They found a significant increase in the number of severe storms over the UK as a whole since the 1950s. This analysis is being extended back in time using newly-digitised MSLP data from as many as possible long-period observing sites in the UK and Ireland, and some preliminary results are shown in Figure 1.14 (Allan et al. in preparation). It appears that an equally stormy period to those in the most recent full decade (1990s) was experienced in the 1920s. Similar conclusions are drawn in IPCC AR4 (Chapter 3, para 18.104.22.168 and Fig. 3.41).
Whereas it is not our purpose here to discuss detailed links between the NAO and storminess, it will be immediately apparent that the two stormiest periods in Figure 1.14, in the 1920s and 1990s, coincide with decades of sustained positive NAO index, whereas the least stormy decade, the 1960s, is a time when the smoothed NAO index was most negative (see Figure 1.13). Although work by Gillett et al. (2003) has shown that man-made factors have had a detectable influence on sea-level pressure distributions (and hence atmospheric circulation patterns) over the second half of the 20th century, there continues to be little evidence that the recent increase in storminess over the UK is related to man-made climate change.
Figure 1.14: The total number of severe storms per decade over the UK and Ireland during the half year period October to March, from the 1920s to the 1990s. Error bars show ± one standard deviation. (Source: Rob Allan, Met Office Hadley Centre)
We know, of course, that there have been no storms since the Burns Day storm which have been as strong. Equally, we know that there have no months as stormy as 1990 or 1993 since either. It therefore seems reasonable to assume that the trend, identified on the graph, has not worsened, and has probably reduced. (I am sure the UKCP Report would have highlighted it, if the trend had increased).
So the bottom line appears to be – it is just weather, we have had much worse in the past, and undoubtedly will again in the future.