Thoughts On Storm Eunice

By Paul Homewood

Eunice was undoubtedly one of the most powerful storms of recent years, so it’s time to sit back and reflect:

 

 

Forecasting

Congratulations to the Met Office who pretty much got their forecasting right.

They predicted winds along the Bristol Channel of 80 to 90 mph, and 60 to 70 mph generally across the south.

The BBC however tended to overestimate wind speeds. Certainly up here in Sheffield, where they were touting 70 mph gusts even that morning. The Met Office said 60 mph, and the actual was 55 mph.

Comparison with other storms

Although powerful, Eunice was not dissimilar to other recent storms in recent years in terms of wind. In particular, the February 2014 storm, Doris in 2017 and Ciara in 2020.

If we ignore the measurements at the Needles, there is similarity for both exposed coastal sites, and inland ones.

	Eunice	Ciara	Doris	Feb 2014
Coastal	87	93	82	108
Inland	70-80	70-80	70-80	70-80

Wind Gust Speeds  – mph

Geographical coverage was also similar, except for Doris which mainly impacted N Wales and the Midlands.

Because of hyperbolic reporting and our own limited attention spans, we tend to believe that the latest event is always the worst. In reality, storms like Eunice are not uncommon.

Comparison with Burns Day

As I have already explained in earlier posts, there is simply no comparison between Eunice and the Burns Day storm.

Burns Day saw gusts peak at 107 mph at Gwennap Head and Aberporth. At less exposed sites winds reached 97 mph, while large parts of England experienced winds close to 90 mph.

The BBC’s account at the time conveys just how bad it was:

http://news.bbc.co.uk/onthisday/hi/dates/stories/january/25/newsid_3420000/3420797.stm

The Needles

I have already dealt with the ridiculous nonsense of using the Needles for climatological purposes, as this chart makes clear:

But I will add that the Met Office have now confirmed to me that wind readings began there in 1996.

That gust of 122 mph is now being declared as a record for England. Yet we had no meter there in 1990 when the Burns Day storm struck, or other earlier storms, which we know were much stronger.

No records of any description should be verified with such a short data period.

Long term trends

The Met Office included this table in its State of the Climate a couple of years ago. It clearly shows that storm activity peaked in the 1980s and 90s. Storm frequency and strength in the last decade appears to be back to 1970s levels:

https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/joc.6213

One likely factor in the 1990s storms, including of course Burns Day, was that the Arctic was in a much colder phase, creating a bigger temperature differential with the warmer air to the south.

It is this differential which powers storms at temperate latitudes.

https://data.giss.nasa.gov/gistemp/maps/

  UK Wind Speed Records

The Met Office track wind speed records by district. The pattern corresponds with the above graph, with most records set in the 1980s and 90s.

It is interesting that the Burns Day storm does not feature at all, suggesting that it was not particularly extreme by the standards of the time.

https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-climate-extremes

The stormy 1920s

The UK Climate Projections Report of 2012 looked at a longer period of record:

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 3.8.4.1 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)

As we know, the latest decade has become much quieter again, compared to the 1990s. This strengthens that conclusion about the effect of climate change.