The Heathrow snow chaos report is out: Rare rate of snowfall since records began (6 years!)?

Originally blogged at Realclimategate

A report into last December’s snow chaos at Heathrow Airport is out, entitled Heathrow Snow Resilence Enquiry

It includes a little reminder to perhaps reflect the new thoughts on ‘climate disruption’ vs global warming (man made).

Even under global warming, periods of extreme cold are still possible for the UK (54)

I thought this was quite funny, the hourly rate of snowfall was considered rare, Rare since records began (6 years!)

The rate of snow that fell at Heathrow was rare
52
The most significant feature of the snow event of 18 December at Heathrow may have been the rate at which snow fell, with nearly 7cm falling within the hour prior to midday. This is rare at Heathrow. A snowfall rate of 7cm in one hour has not been observed at Heathrow since hourly records began in 2005. Daily snowfall increments of 7cm or more have occurred only six times since 1970. Rates of snowfall at Gatwick and Stansted for this event did not exceed 5cm in one hour and 3cm in one hour respectively.

Perverse Weather Events – or just weather?

The Chief scientists for the Department of Transport:

“There is a general trend for the mean atmospheric temperature across the planet to increase. But whilst that is happening local conditions may well produce perverse weather events.” – Professor Brian Collins

From the Executive Summary an overview of what occured at Heathrow and a summary of the cold weather event. The executive summary puts the disruption into context, and on the whole it appears to be a very comprehensive and clear report with good advice and sensible recommendations

1 The unusual weather conditions experienced in Heathrow in December caused disruption on a number of fronts. Passengers were unable to travel at an important time of the year; over 4,000 flights were cancelled, causing significant impact to airline schedules globally; and Heathrow Airport‟s reputation was damaged.

It is just the weather and global warming comments that stand out, based on the best advice received by the panel from the usual experts:

The panel has sought expert scientific advice from the Met Office and the DfT on the implications of global warming on the future likelihood of and scale of snow events at Heathrow.

The weather during the month of December was unusual. It was the coldest December for 100 years. There were two extended snowfalls during the month, the first early in December, with Gatwick and Stansted experiencing significant snowfalls, but with less snow at Heathrow. All three airports were affected by the second snowfall. The actual snowfall at Heathrow (over the crisis period) occurred on the morning of Saturday the 18th – which resulted in a maximum snow depth of 9cm.

55 The panel heard from Professor Brian Collins, DfT‟s Chief Scientific Advisor, that: “There is a general trend for the mean atmospheric temperature across the planet to increase. But whilst that is happening local conditions may well produce perverse weather events.”

56 This trend was also reported in David Quarmby‟s Winter resilience report: “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. Whensevere weather events happen they may be more extreme in terms of heat and rainfall. Although the probability of severely cold winters in the UK is gradually declining, there is
currently no evidence to suggest similar changes in episodes of extremes of snow, winds and storms in the UK”3.
57 The Chief Scientific Advisor of the Met Office supported the above views. The panel noted that further, more focused, research will commence in this area, led by the Met Office, and urges BAA to understand the implications of any subsequent findings from this research.

The report states that the cold weather was predicted a few days out by the Met Office and Heathrows weather service. Thus Heathrows Airports failings should be considered due to not responding to ‘weather’ (not climate) short term predictions, this should have given Heathrow time to prepare. It is only where the ‘global warming’ and ‘climate science’ creeps in to the report that perhaps some assumptions and comments seem odd.  This is in no noubt, no fault of the panel as they of course sought the appropriate expert advice

The Guardian has an article about it here:

Guardian: Airports will spend £50m to avoid repeat of Heathrow snow chaos

“BAA to invest in snow-clearing machines and more staff – with the aim that bad weather will never again close Heathrow”

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