Think twICE
5.5.3.2 Road surface temperatures (RSTs)
The MET Office web site states that :
‘Met Office weather forecasts tell us when freezing temperatures are expected in our local area and many of us are inclined to keep an eye out for zero or minus temperatures as an indicator of when it could be icy. Nevertheless, it may come as a surprise that even when air temperatures are as high as four or five degrees Celsius, ground temperatures often dip below freezing so that ice is possible. ‘A banner on the MET Office web site summarises this :-
''Even when air temperatures are as high as four or five degrees Celsius, ground temperatures often dip below freezing so that ice is possible''
Unfortunately, it is very unusual for the weather forecasts to specify that when forecasting ‘temperature’ it means an air temperature 1 metre above the ground i.e. not the road surface temperature.
This confusion directly led to a large scale incident of cyclists falling off their bikes at an event in South Gloucestershire in January 2015. One cyclist broke an arm in two places and another needed a hip replacement. The organisers had relied upon a weather forecast predicting ‘temperatures’ above 3 degrees. Very few of the general public in my experience understand the important difference between RSTs and MET Office temperature forecasts
Delivery of the winter service therefore depends on the receipt of accurate forecasts of road surface temperature and state, together with humidity which is critical when conditions are marginal, such as when temperatures are close to zero.
It is the road surface temperature and whether the road is wet or dry that determines whether ice will form, rather than the air temperature
RSTs are routinely forecast internally by the MET Office as they are essential when a forecast for ice is actually published. But RSTs are not published. However the equivalent for gardeners is published i.e. a ground frost. A ground frost is published at times when tender plants could be at risk.
Local authority contracts for gritting weather services require accurate RST predictions.
The MET Office approach so far has been to issue advice on their web site. I was asked to comment on this advice. Correspondence on this issue is in the supporting information xxxxsection sub tab (to be added)
In summary:
1 The advice should be simple and clear. However the information is very complex and incomplete illustrating how important it is for the MET Office to forecast RSTs rather than provide the general public with ‘DIY’ weather forecasting advice.
As an example of incompleteness, the MET Office has access to near-realtime road and air temperature data from Highways England, which is not proprietary data, but they do not make this available to the public.
2 Only a very small proportion of the cycling public will be aware of this information
3 The information could have the unintended effect of dissuading cyclists from riding in much of the winter when it is quite safe to do so. This is because it emphasises the extent to which RSTs can be significantly lower than air temperatures. However the reverse can be true, particularly at the start of the winter season.
‘Advice should be simple and clear
The MET Office have recently installed a super-computer capable of 13000 trillion calculations a second, the most powerful of its type outside the USA. The general public cannot hope to match this capability. In order to support the public making an informed decision to travel I believe that the super computer should be put to use to support the publication of RST forecasts to the public as well achieving overall improvements in ice forecasting as called for in paper ‘Recommendations for improvements in MET Office ice predictions’ ref https://icycleweather.wixsite.com/iceandcycling/2-ice-forecasting-paper
‘Instead of expecting the public to follow complex and incomplete advice on ice prediction, the new MET Office super computer should be used for this purpose starting with the publication of road surface temperatures’ (RSTs)’
The original Public Weather Service Customer Group (PWSCG) reservation to publishing Road Surface Temperatures was the cost involved. I submitted a paper xxx that explained that this could be achieved at a modest cost. The PWSCG then modified its response during a telephone conference of 8 November. This modified response made clear that it is not within the gift of the PWSCG to require the MET Office to publish road surface temperatures as part of the Public Weather Service. The PWSCG advised that RSTs were only published on a commercial basis.
On 8 November 2016 the PWSCG advised during a telephone conference, later conformed in writing, that it was not within their gift to require the MET Office to publish road surface temperatures which were only published on a commercial basis. The relevant exchange of emails is provided below:-
Email to PWSCG 8 November 2016
Would you please pass on to xxxx my thanks for arranging today's conference call .It was very helpful . I quite understand that xxxx needs to assure herself that any additional PWS services are thoroughly researched. I am very grateful that she expressed appreciation for my work .
I am looking forward to seeing the link to each of the local authority web site locations for the information about road gritting. I am sure my cycling colleagues will be please to have a permanent link available through the MET Office.
Just one point of clarification which I did not raise at the meeting as it was incidental to the outcome. I think you mentioned that the PWS does not produce road temperature forecasts and that these are only available as a paid for service. It does not 'publish' these forecasts but it does of course produce them as they are an essential part of producing ice forecasts. I explained this in my email of 12 September which I followed up with the Paper which proposed that road forecast temperatures could be published at a modest cost. They would only need to be as detailed as the forecast used to predict ice and not as complex as those sold as part of the Open Roads Service.
Kevin
Reply from PWSCG on 9 November 2016 to above email of 8 November 2016
Kevin,
In response to your point of clarification:
I think you mentioned that the PWS does not produce road temperature forecasts and that these are only available as a paid for service. Yes but only for the roads the Met Office is contracted to forecast for. It does not 'publish' these forecasts. Correct and it is not within the gift of the PWSCG to do so. These forecasts are provided on a commercial basis. but it does of course produce them NO – PWS does not produce any road surface temperature forecasts as they are an essential part of producing ice forecasts. I explained this in my email of 12 September which I followed up with the Paper which proposed that road forecast temperatures could be published at a modest cost. They would only need to be as detailed as the forecast used to predict ice and not as complex as those sold as part of the Open Roads Service.
I will send a summary of the meeting tomorrow or Friday.
In subsequent correspondence I :-
1 Commented that this statement conflicted with the MET Office’s ‘free at the point of use’ obligation to provide weather information that allowed to enable the UK public to make informed decisions about their safety
2 Offered a work round plan that should not conflict with MET Office commercial aspirations. This pointed out that there would be a considerable improvement in the Public Weather Service without divulging the detail needed to secure a commercial contract eg post code forecasting offered by Road Cast operated by the Meteo Group
3 Asked to be advised which organisation set this constraint on the PWSCG so that a member of the public could make representations
4 Requested that the PWSCG publish any other constraints of this type
No response has been received to these above four points.
Is the reason that it is not in the gift of the PWSCG to require the MET Office to publish road surface temperatures because the MET Office considers commercial business more important than the Public Weather Service?
Evidence presented to PWSCG that Road Surface Temperature forecasting can be produced at a modest cost
The following exchange of emails between myself and the PWSCG explains why I believe that road surface temperature forecasting can be introduced at a modest cost with no additional resources
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Extract of email from PWSCG to Kevin Daniels 9 September 2016
Thank you for providing your summary as to why ice forecasts are important for cyclists I will ensure this is maintained for future reference. Just to clarify the judgement the forecasters make about whether there is a risk of frost does not exist in a publishable form, only in their head. It may sound trivial to suggest that it is converted into a product but there is a cost associated to ensure that it is produced in a robust, reliable and consistent form. The forecasters are on duty all of the time, but are already occupied producing the very many forecasts the Met Office provides on a daily basis.
2 Email from Kevin Daniels to PWSCG 19 September 2017
Thank you for your email of 9 September
The principle reason for this email is to explain using a diagram (see at the foot of this page) the reasoning behind the proposal I made in my email of 29 August about road temperature forecasting. I hope this helps in getting across these points: -
1 The method of prediction of road temperature is the same for predicting ice or just road temperature. Both outputs therefore will be to the same levels of robustness, reliability and consistency
2 The forecasters on duty need to have the capacity to forecast ice in the winter period.
3 It is only necessary to publish forecasts for ice OR road temperature, not both.
4 When the forecasters are not using road temperature to forecast ice they will therefore have the capacity to forecast road temperatures on a stand-alone basis. So I conclude that he addition of road temperature forecasting will not require more resources. You made the point that the forecasters are already occupied-the point . I was trying to make is that they will either be occupied making ice forecasts or road temperature forecasts. Therefore, road temperature forecasting does not place an additional task on occupied forecasters.
5 No new processes are involved in forecasting road temperatures
I hope this is sufficiently clear and that we can find a way ahead on this before the winter season starts. If not, I am sure a quick phone call would help.
3 Extract of email from PWSSCG to Kevin Daniels 30 September2016
‘I’m afraid it is not quite as straightforward as you suggest.’
4 Conclusion on this exchange of emails
The email response of 9 September raises specific points which I feel were comprehensively responded to in my email of 19 September with supporting evidence. The response to my email of 19 September raises no specific points. I am left with the conclusion that any residual concerns are not substantial otherwise they would have been mentioned.
I appreciate that no change can take place without some impact even if this is limited to the establishment of new procedures and the subsequent communication of these procedures. So I assume that the statement that ‘it is not quite as straightforward as you assume’ refers to set-up activities such as these.
The National Severe Weather Service provides accurate information on the location of risks (such as ‘severe ice’) by drawing a contour around the affected area. Start and finish times are included. The MET Office is staffed always to be able to produce this information. Road temperature assessment is a part of the process in arriving at a ‘severe ice‘ weather warning.
I there therefore conclude that road temperature contours can be produced hourly with existing staffing and at a modest cost. If these temperature contours are not used to produce ‘severe ice’ weather warnings, then they can be published on a stand-alone basis so that cyclists can use their local knowledge of water seepage to make an informed decision about their travel
