Winter Resilience & Met Office Advice
With the whole of the UK apparently grinding to a halt with the cold and snow, it was interesting to be pointed to an official review of the UK’s winter resilience capabilities (H/T John B).
A small team was set up under the leadership of Dr David Quarmby, a member of the “great and good” with background in transport. The team published its terms of reference here; an interim report was published last summer, and the final report appeared just a couple of months ago.
For our purposes the interim report is more interesting since it has a whole section entitled “Weather forecasting and climate change”. All emphasis below is added by me.
12.7 The science of forecasting up to 30 days ahead and beyond has made great progress in recent years and will continue to develop; comparison of outturns against probabilistic predictions out to 30 days suggests that the information is of increasing value for winter service resourcing and planning.
“Increasing value” eh? I wonder what the absolute value of these forecasts is though?
12.8 The Met Office has ceased publishing seasonal forecasts through the PWS, because – again – the nature of the weather and climate means that at these timescales it only makes sense to give probabilistic predictions rather than definitive forecasts, and this has proved difficult to communicate.
“Difficult to communicate”? Don’t they mean that they were wrong? I’m struggling with the idea of a “barbeque summer” that turned into a rain-drenched washout being a communication problem.
12.9 Yet, as this Review makes clear, critical policy and strategic decisions would be enormously enhanced by even a probabilistic prediction about next winter’s weather. Forecasting over this timescale and beyond takes us into the area of climate forecasting and the impact of climate change.
12.10 We have explored these issues in some depth with the climate research team at the Met Office Hadley Centre. The starting point is the slow but steady rise in average global temperatures. The consensus on the UK is that on average summers will become warmer, and winters will become warmer and wetter, though the next 10–15 years may be dominated by natural variability. When severe weather events happen they may be more extreme in terms of heat and rainfall.
Aha! So the Met Office were involved, and told the review that winters were going to become warmer and wetter. What else did they say?
12.11 Although the probability of severely cold winters in the UK is gradually declining, there is currently no evidence to suggest similar changes in extremes of snow, winds and storms in the UK.
12.12 We have also explored whether or not the occurrence of two successive severe winters influences the probability of a third in succession – in other words, is there any evidence of clustering? There is some small influence from year to year but these matters are still very uncertain and it would be safer to assume that there is statistical independence between one winter and the next.
12.13 In other words, we are advised to assume that the chance of a severe winter in 2010–11 is no greater (or less) than the current general probability of 1 in 20.
Now didn’t the Met Office tell us just yesterday that they didn’t make any predictions on the weather for this winter? I would have thought many people might have mistaken the words highlighted above as discussing a forecast of some kind. Perhaps it’s another of those communication difficulties.
12.14 For the purpose of this report, the following summarises what we understand:
- The probability of the next winter being severe is virtually unrelated to the fact of just having experienced two severe winters, and is still about 1 in 20.
- The effect of climate change is to gradually but steadily reduce the probability of severe winters in the UK.
- However, when severe winters come, they could still be extreme – in terms of snowfall, wind and storms,though not necessarily in relation to temperature.
12.17 But we need to understand and accept that the chance of a severe winter is still relatively small and that there will be many years when some will question the degree of resources committed to winter resilience.
12.15 An important consequence of the declining occurrence of severe winters is the loss of knowledge and experience among planning and technical staff in local highway authorities and their contractors, especially if the severe winters which do occur have more extreme snow events.
12.16 All this, in our view, reinforces the need for comprehensive resilience planning, and for ensuring that the salt supply chain is resilient.
After the publication of the interim review, the team recommendedthat the UK import 250,000 tonnes of salt to cope with a possible shortfall. I wonder if this was (a) enough and (b) actually done in practice.
Either way, this looks like more trouble for the Met Office.